(19)
(11)EP 3 083 271 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
20.11.2019 Bulletin 2019/47

(21)Application number: 14766468.4

(22)Date of filing:  15.09.2014
(51)International Patent Classification (IPC): 
B60C 1/00(2006.01)
C08G 18/48(2006.01)
C08G 18/63(2006.01)
C08G 101/00(2006.01)
C08G 18/08(2006.01)
B29K 105/04(2006.01)
B29D 30/02(2006.01)
B29C 41/00(2006.01)
B60C 7/00(2006.01)
C08G 18/40(2006.01)
C08J 9/14(2006.01)
C08G 18/10(2006.01)
B60C 7/10(2006.01)
B29K 105/00(2006.01)
B29C 41/04(2006.01)
B29K 75/00(2006.01)
(86)International application number:
PCT/EP2014/069609
(87)International publication number:
WO 2015/090653 (25.06.2015 Gazette  2015/25)

(54)

POLYURETHANE FILLED TIRES

REIFEN, GEFÜLLT MIT POLYURETHAN

PNEUS REMPLIS DE POLYURÉTHANE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 20.12.2013 EP 13198741
20.12.2013 IN 3729DE2013

(43)Date of publication of application:
26.10.2016 Bulletin 2016/43

(73)Proprietor: Huntsman International LLC
Salt Lake City, UT 84108 (US)

(72)Inventors:
  • VAN DYCK, Johan
    B-3670 Meeuwen-Gruitrode (BE)
  • NICLAES, Dieter
    B-3370 Boutersem (BE)
  • SAHU, Siddharth
    B-3080 Tervuren (BE)

(74)Representative: Van den Broeck, Kristel Alice et al
Huntsman (Europe) BVBA Intellectual Property Department Everslaan 45
3078 Everberg
3078 Everberg (BE)


(56)References cited: : 
WO-A1-2009/129944
US-A- 4 206 170
US-A- 4 125 691
US-B1- 6 303 060
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    FIELD OF INVENTION



    [0001] The present invention relates to methods for improving the dynamic performance of tires, in particular bicycle tires, made of a cellular polyurethane elastomeric material. More specifically reducing the rolling resistance of the polyurethane elastomer. Therefore, the invention relates to a specific developed polyurethane elastomer.

    [0002] The present invention relates to methods for making polyurethane tires with improved dynamic performance while maintaining good hydrolysis resistance and wear resistance.

    [0003] The present invention further relates to a method for making polyurethane elastomers suitable for use as tires, thereby controlling phase separation issues while using rotating moulding for fabricating the tires.

    [0004] The present invention further relates to a reactive composition comprising polyisocyanates and polyisocyanate reactive products for making the polyurethane elastomeric tires according to the invention.

    [0005] The present invention further relates to tires, preferably bicycle tires made of a polyurethane elastomer.

    BACKGROUND OF THE INVENTION



    [0006] Pneumatic tires are commonly used in on-road vehicles such as automobiles and trucks. Pneumatic tires have the advantages of being light in weight and providing a soft and comfortable ride, because the tire casing is filled with a gas or air. The main disadvantage of pneumatic tires is the risk of deflation due to punctures, separation of the tire casing from the rim, or other failure of the tire casing or rim.

    [0007] US6303060 discloses a non-deflatable tire assembly having a hollow toroid-shaped flanged insert and a flexible body molded around the insert to form a tire, and at least one rim onto which is mounted the tire. The flexible body is made of a polyurethane foam formed of a combination of polyol and polyisocyanate, while the insert is made of another material such as high density polyethylene. The hollow insert itself is required to provide load carrying stiffness to the tire, thereby contributing to a cushioned ride. Although the hollow internal area is reduced in dimension, the tire is not completely non-deflatable and hollow areas are still required to achieve acceptable mechanical properties. Furthermore, the polyurethane foam used has a too high compression set value (in the range 10-20%).

    [0008] US4125691 discloses a zero pressure device composed of either a microcellular or homogeneous polyurethane made by reacting an organic polyisocyanate with at least three polyols, a monomeric polyol of 2 to 3 hydroxyls having a molecular weight less than 250, a polyether triol having a molecular weight of 4600 to 6000 and a polyether glycol having a molecular weight of 3500 to 4200. The organic polyisocyanate used is a quasi prepolymer made by reacting MDI with a polypropylene ether triol. US'691 further discloses examples wherein 2 pbw acrylonitrile grafted polypropylene ether glycol (polymer polyol) is added to the reactive mixture. Using polypropylene based quasi prepolymers will lead to polyurethane materials having a too low ball rebound and a too low hardness will be achieved due to insufficient amounts of polymer polyols.

    [0009] For above reasons, filled tires are more attractive than pneumatic tires. A filled tire contains a solid or semi-solid material instead of a compressed gas. This eliminates the risk of deflation, as a puncture or other failure of the tire casing will not lead to an escape of gas.

    [0010] However a tire fill material should meet several requirements to compete with the good dynamic properties of pneumatic tires. For example the tire fill material should allow the tire to absorb shock and provide good traction. Therefore, the tire fill material should be soft and flexible. In addition, the tire fill material should be such that the tire does not build up excessive heat during use, as the heat can damage the fill material or the casing and thus diminish the useful life of the tire. In addition, cost is a very important concern.

    [0011] Soft polyurethane/urea elastomers have been used as a tire fill material in the past and several approaches have been tried. In some cases, the polyurethane/urea polymer has been foamed using carbon dioxide that is generated in a reaction between water and an organic isocyanate. Such an approach is described in US 3605848. These foams have the advantages of light weight due to their cellular nature, and of being too soft and the foams tend to exhibit high hysteresis and high heat build-up.

    [0012] Polyesterol-containing soft phases lead to the highest level of dynamic properties in cellular PU elastomers having a urea hard phase. Products of this type are also well known. For example WO 2001018086 describes the use of polyester polyetherol obtainable via polycondensation of polyoxytetramethylene glycol whose average molar mass is from 220 to 270 g/mol and adipic acid, for the production of cellular polyurethane elastomers with good dynamic properties and with high low-temperature flexibility. However, the ester bonds make the resultant foam susceptible to hydrolysis.

    [0013] DE-A 3613961 describes the production of products based on pure polyester soft phases and, respectively, polyester-polyetherol soft phases. The test specimens based on polytetrahydrofuran (M=2000 g/mol) as soft phase in the comparative example in DE-A 3613961 had only comparatively low flexural strength.

    [0014] The overall disadvantage of the cellular polyurethane elastomers known in the prior art and used for tires is fact that they do not retain the desired shape if the polyurethane elastomer is subject to an increased temperature and they do not withstand contact with moisture and/or to high pressure acting on the elastomer.

    [0015] For all reasons above indicated there is a need to develop a new polyurethane elastomeric material which has very good dynamic properties and which is able do retain the desired shape if the polyurethane elastomer is subject to an increased temperature and to withstand contact with moisture and/or to high pressure acting on the elastomer.

    AIM OF THE INVENTION



    [0016] It is a goal of the invention to improve the properties of a polyurethane elastomer such that its dynamic performance and resistance (more specific hydrolysis resistance and wear resistance) are satisfactory for use as bicycle tires and becomes comparable to pneumatic tires.

    [0017] It is a further object of the present invention to develop a reactive composition and a method for making solid tires, more particular bicycle tires, made of a cellular (foamed) polyurethane elastomeric material.

    SUMMARY OF THE INVENTION



    [0018] This invention relates to reaction systems for making polyurethane elastomeric compositions for making tires, to the use of the reaction system for making said tires and to tires made of said polyurethane elastomers. Said tires are in particular suitable for use as tires for low speed vehicles such as bicycle tires, however the invention is not limited to bicycle tires (such as tires for wheelchairs, trolleys, push-carts, pull-carts,...).

    [0019] Surprisingly we have found a cellular (foamed) polyurethane elastomeric material that has satisfactory dynamic performance and thereby maintains excellent hydrolysis resistance and wear resistance performance. The polyurethane elastomeric composition according to the invention makes it possible to compete with the properties of pneumatic tires. On top of that the polyurethane elastomeric tires according to the invention are solid tires (made of cellular polyurethane) which reduces the risk of deflation due to punctures, separation of the tire casing from the rim, or other failure of the tire casing or rim to almost zero.

    [0020] According to a first aspect, a reaction system for making a filled tire made of a cellular polyurethane or polyurethane-urea elastomeric material is disclosed, said elastomeric material having the following properties:
    • Shore A hardness (according to ASTM D2240) of at least 45 and lower than 85, preferably in the range 45-80;
    • Compression set at room temperature lower than 10 % and at 70°C lower than 40 % (according to ASTM D395);
    • Ball rebound (according to ASTM D3574) of at least 40%, preferably from 40 to 70%;


    [0021] According to embodiments of the invention, the tire is a low speed vehicle tire such as a bicycle tire.

    [0022] According to embodiments of the invention, the tire is made of a cellular polyurethane elastomeric material having a moulded density in the range 400-700 kg/m3, preferably in the range 500-600 kg/m3 and a Free Rise Density in the range 250-350 kg/m3, preferably in the range 300-320 kg/m3 (according to ISO 845)
    The reaction system of the invention for making the cellular polyurethane elastomer according to the invention is comprising at least:
    • a polyisocyanate composition having a free NCO-value of 15-25% by weight comprising an isocyanate-terminated prepolymer which is the reaction product of an excess of an organic polyisocyanate and a polyether polyol having an average nominal hydroxyl functionality of 2-6, a number average molecular weight of 2000-6000 and an ethylene oxide content of 20-35% by weight, wherein at least 50% of the ethylene oxide groups are present at the end of the polyether polyol, and
    • at least one polymer polyetherpolyol having a molecular weight in the range 2000-7000 and having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol; and
    • chain extenders, and
    • catalysts, and
    • blowing agents


    [0023] According to embodiments of the invention, the organic polyisocyanates used in the reaction system for the preparation of the polyisocyanate according to the invention is selected from aliphatic, cycloaliphatic and/or araliphatic polyisocyanates, preferably selected from aromatic polyisocyanates, more preferably from diphenylmethane diisocyanate (MDI) based polyisocyanates, most preferably diphenylmethane diisocyanate (MDI) based polyisocyanates having > 95 % wt 4,4'-MDI calculated on the total weight of the organic polyisocyanate mixture.

    [0024] According to embodiments of the invention, the polyether polyols used for preparing the prepolymer in the reaction system for the preparation of the polyisocyanate composition according to the invention contain 20-35% by weight ethylene oxide groups wherein at least 50%, preferably at least 75% and more preferably all (100%) of these ethylene oxide groups are present at the end of the polyether polyol (tipped) and wherein said polyether polyols have an average nominal functionality of 2-6, preferably of 2-4, a number average molecular weight of 2000-6000 and preferably 2000-5000 and most preferably of 3000-5000.

    [0025] According to embodiments of the invention, the polyether polyols used for preparing the prepolymer in the reaction system for the preparation of the polyisocyanate composition according to the invention are selected from poly(oxyethylene-oxypropylene) diols and triols.

    [0026] According to embodiments of the invention, the at least one polymer polyetherpolyol in the reaction system according to the invention is selected from a filled polyether polyol having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol and is having an ethylene oxide content of maximum 20 % by weight, preferably in the range 10-20 % by weight and wherein the ethylene oxide groups are present at the end of the polyether polyol (tipped).

    [0027] According to embodiments of the invention, the at least one polymer polyetherpolyol in the reaction system according to the invention is selected from a filled polyether polyol having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol and wherein said polymer polyol is a dispersion of polymer solid particles such as styrene based polymer particles, preferably styrene-acrylonitrile particles.

    [0028] According to embodiments of the invention, the at least one polymer polyetherpolyol in the reaction system according to the invention is a mixture of a first polyether polyol and a second polyetherpolyol having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol mixture and wherein
    • the first polyetherpolyol is having a molecular weight in the range of 5000-7000 and an ethylene oxide content of 10-20 % by weight and the ethylene oxide groups are present at the end of the polyether polyol (tipped)
    • the second polyetherpolyol is having a molecular weight in the range of 4000-6000, preferably around 5000 and an ethylene oxide content of 10-20 % by weight and wherein the ethylene oxide groups are present at the end of the polyether polyol (tipped), and
    • the molecular weight of the mixture is preferably in the range 4000-7000 and wherein the ratio of the first polyetherpolyol to the second polyetherpolyol is preferably in the range 20/80 up to 40/60


    [0029] According to embodiments of the invention, the at least one polymer polyetherpolyol in the reaction system according to the invention is a mixture of a first polyether polyol and a second polyetherpolyol having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol mixture and wherein
    • the first polyetherpolyol is having a molecular weight in the range of 1000-2000 and is selected from polytetrahydrofuran
    • the second polyetherpolyol is having a molecular weight in the range of 4000-6000, preferably around 5000 and an ethylene oxide content of 10-20 % by weight and wherein the ethylene oxide groups are present at the end of the polyether polyol (tipped), and
    • the molecular weight of the mixture is preferably in the range 2000-4000 and wherein the ratio of the first polyetherpolyol to the second polyetherpolyol is preferably in the range 80/20 up to 40/60


    [0030] According to embodiments of the invention, the blowing agents used in the reaction system according to the invention are selected from fluor based hydrocarbon compounds (hydrofluorcarbon compounds) and/or acetal based compounds and/or water.

    [0031] According to embodiments of the invention, the blowing agent(s) used in the reaction system according to the invention is an acetal based compound such as methylal and is used preferably in the absence of other blowing agents in the range 4-8 wt % calculated on the total weight of the reaction system.

    [0032] According to embodiments of the invention, the blowing agent(s) used in the reaction system according to the invention is water, preferably in the absence of other blowing agents, and is used in the range of at least 0.3 parts by weight, preferably from 0.3 to 1.3 parts by weight, per 100 parts of the reaction system.

    [0033] According to embodiments of the invention, the reaction system according to the invention may further comprise additives like catalysts, surfactants, colorants, stabilisers, fillers and mold release agents.

    [0034] According to embodiments of the invention, the chain extender(s) and/or cross-linkers used in the reaction system according to the invention are selected from polyols having an hydroxyl functionality of 2-6 and preferably 2-4 and a molecular weight of 62-499 such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butane diol, glycerol, trimethylolpropane, hexanediol, pentaerythritol and polyethylene glycols of MW of 499 and less and wherein the amount of chain extenders and cross-linker is at most 15 parts by weight per 100 parts by weight of polyol used to react with the polyisocyanate composition, more preferably the amount of chain extenders and cross-linker is in the range 5-15 parts by weight per 100 parts by weight of polyol used to react with the polyisocyanate composition.

    [0035] According to embodiments of the invention, the chain extender(s) and/or cross-linkers used in the reaction system according to the invention is selected from mono ethylene glycol (MEG), butanediol and/or hexanediol.

    [0036] According to a second aspect, the use of the reaction system according to the invention for making a polyurethane elastomer according to the invention is disclosed, said use comprising reacting at an isocyanate index in the range 90-110, preferably in the range 100-105 the reactive system according to the first aspect of the invention.

    [0037] According to embodiments of the invention, the use of the reaction system according to the invention for making the polyurethane elastomer according to the invention is such that the polymer polyetherpolyol is premixed with the chain extenders, catalysts, blowing agents, and other additives and then reacted with the polyisocyanate composition.

    [0038] According to embodiments of the invention, the use of the reaction system according to the invention for making the polyurethane elastomer according to the invention comprises at least the steps of:
    1. i. pre-mixing the polymer polyetherpolyol with the chain extenders, catalysts, blowing agents, and other additives, and then
    2. ii. mixing the polyisocyanate composition with the pre-mixed polymer polyetherpolyol obtained in step i) and then
    3. iii. casting the mixed polyisocyanate composition obtained in step ii) into a mould to obtain a reacted polyisocyanate composition, and then
    4. iv. curing the reacted polyisocyanate composition obtained in step iii) at an elevated temperature, and then
    5. v. demoulding the obtained tire made of polyurethane cellular elastomer.


    [0039] According to embodiments of the invention, the use of the reaction system according to the invention for making the polyurethane elastomer according to the invention is such that the step of mixing the polyisocyanate composition with the pre-mixed polymer polyetherpolyol obtained in step i) is performed using a 2 component high pressure mixing system or a 2 component dynamic mixing system.

    [0040] According to embodiments of the invention, the use of the reaction system according to the invention for making the polyurethane elastomer according to the invention is such that the step of casting the mixed polyisocyanate composition obtained in step ii) is performed using an open mould, preferably a rotating open mould preferably at a rotation speed in the range 150-250 rpm and wherein the step of curing the reacted polyisocyanate composition obtained in step iii) is performed at elevated temperatures in the range 50-60 °C.

    [0041] The independent and dependent claims set out particular and preferred features of the invention. Features from the dependent claims may be combined with features of the independent or other dependent claims as appropriate.

    [0042] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying examples which illustrate, by way of example, the principles of the invention.

    DEFINITIONS AND TERMS



    [0043] In the context of the present invention the following terms have the following meaning:
    1. 1) The isocyanate index or NCO index or index is the ratio of NCO-groups over isocyanate-reactive hydrogen atoms present in a formulation, given as a percentage:


      In other words the NCO-index expresses the percentage of isocyanate actually used in a formulation with respect to the amount of isocyanate theoretically required for reacting with the amount of isocyanate-reactive hydrogen used in a formulation.
      It should be observed that the isocyanate index as used herein is not only considered from the point of view of the actual polymerisation process preparing the material involving the isocyanate ingredients and the isocyanate-reactive ingredients. Any isocyanate groups consumed in a preliminary step to produce modified polyisocyanates (including such isocyanate-derivatives referred to in the art as prepolymers) or any active hydrogens consumed in a preliminary step (e.g. reacted with isocyanate to produce modified polyols or polyamines) are also taken into account in the calculation of the isocyanate index.
    2. 2) The expression "isocyanate-reactive hydrogen atoms" as used herein for the purpose of calculating the isocyanate index refers to the total of active hydrogen atoms in hydroxyl and amine groups present in the reactive compositions; this means that for the purpose of calculating the isocyanate index at the actual polymerisation process one hydroxyl group is considered to comprise one reactive hydrogen, one primary amine group is considered to comprise one reactive hydrogen and one water molecule is considered to comprise two active hydrogens.
    3. 3) The term "average nominal hydroxyl functionality" (or in short "functionality") is used herein to indicate the number average functionality (number of hydroxyl groups per molecule) of the polyol or polyol composition on the assumption that this is the number average functionality (number of active hydrogen atoms per molecule) of the initiator(s) used in their preparation although in practice it will often be somewhat less because of some terminal unsaturation.
    4. 4) The word "average" refers to number average unless indicated otherwise.
    5. 5) "Liquid" means having a viscosity of less than 10 Pa.s measured according to ASTM D445-11a at 20 °C.
    6. 6) "pbw" means part by weight.
    7. 7) The term "reaction system" refers to a combination of ingredients wherein the polyisocyanate composition is kept in a container separate from the isocyanate-reactive ingredients.
    8. 8) The term "filled tires" as used herein refers to tires which do not contain hollow inserts containing air or compressed gas. These tires are preferably completely made of polymeric materials, such as foamed polyurethane.

    DETAILED DESCRIPTION



    [0044] According to a first aspect of the invention, a reaction system for making a tire made of a cellular polyurethane elastomeric material is disclosed, in particular low speed vehicle tires such as bicycle tires. Said cellular polyurethane elastomeric material is having the following properties:
    • Shore A hardness (according to ASTM D2240) of at least 45 and lower than 85, preferably in the range 45-80;
    • Compression set at room temperature lower than 10 % (according to ASTM D395) and at 70°C lower than 40 %;
    • Ball rebound (according to ASTM D3574) of at least 40%, preferably from 40 to 70%;


    [0045] According to embodiments, the cellular polyurethane elastomeric material according to the invention is having a moulded density in the range 400-700 kg/m3, preferably 500-600 kg/m3

    [0046] According to embodiments, the cellular polyurethane elastomeric material according to the invention is having a Free Rise Density in the range 250-350 kg/m3 preferably in the range 300-320 kg/m3 measured according to ISO 845.

    [0047] According to embodiments, the cellular polyurethane elastomeric material according to the invention is having a compression set at room temperature (according to ASTM D395) lower than 10 %, such as compression set values of 3.4%, 4.3%, 5% and 6%.

    [0048] According to embodiments, the Shore A hardness of the cellular polyurethane elastomeric material according to the invention at least 50 and lower than 85, preferably in the range 50-80.

    [0049] According to embodiments, the Shore A hardness of the cellular polyurethane elastomeric material according to the invention may be different depending on the application. For use as tires in children bikes, the hardness is preferably in the range 45-55, more preferably in the range 50-55 while for use as tires in adult bikes, the hardness is preferably in the range 70-80.

    [0050] According to embodiments, the tire is completely made of the cellular polyurethane elastomeric material according to the invention.

    [0051] According to embodiments, the tire is completely made of the cellular polyurethane elastomeric material according to the invention and may optionally be coated with an additional layer, such as a protective wear layer.

    [0052] The reaction system for making the cellular polyurethane elastomer of the invention is comprising at least:
    1. a) a polyisocyanate composition having a free NCO-value of 15-25% by weight comprising an isocyanate-terminated prepolymer which is the reaction product of an excess of an organic polyisocyanate and a polyether polyol having an average nominal hydroxyl functionality of 2-4, a number average molecular weight of 2000-6000 and an ethylene oxide content of 20-35% by weight, wherein at least 50% of the ethylene oxide groups are present at the end of the polyether polyol, and
    2. b) at least one polymer polyetherpolyol having a molecular weight in the range 2000-7000 and having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol; and
    3. c) chain extenders, and
    4. d) catalysts, and
    5. e) blowing agents


    [0053] The organic polyisocyanates which may be used in the preparation of the polyisocyanate compositions of the invention include aliphatic, cycloaliphatic and araliphatic polyisocyanates, for example hexamethylene diisocyanate, isophorone diisocyanate, cyclohexane-1,4-diisocyanate, dicyclo-hexylmethane-4,4-diisocyanate an p-xylylene diisocyanate.

    [0054] Preferred polyisocyanates, however, are the aromatic polyisocyanates, for example phenylene diisocyanates, tolylene diisocyanates, 1,5-naphthylene diisocyanate and especially the available diphenylmethane diisocyanate (MDI) based polyisocyanates like MDI isomers, that is to say 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate and mixtures thereof.

    [0055] More preferably the amount of 4,4'-diphenylmethane diisocyanate used as organic polyisocyanate is more than 95 wt % calculated on the total weight of the organic polyisocyanate, most preferably the amount of 4,4'-diphenylmethane diisocyanate used as organic polyisocyanate is more than 97 wt % calculated on the total weight of the organic polyisocyanate.

    [0056] Whilst diisocyanates are the preferred polyisocyanates for use in the preparation of the polyisocyanate compositions, mixtures of diisocyanates with minor proportions of higher functionality polyisocyanates may be used if desired. Other MDI variants are well known in the art and include liquid products obtained by the introduction of urethane, allophanate, urea, biuret, carbodiimide, uretonimine and/or isocyanurate residues.

    [0057] According to embodiments, the polyether polyols used for preparing the prepolymer contain 20-35% by weight ethylene oxide groups wherein at least 50%, preferably at least 75% and more preferably all (100%) of these ethylene oxide groups are present at the end of the polyether polyol (tipped). These polyether polyols have an average nominal functionality of 2-6, preferably of 2-4. They have a number average molecular weight of 2000-6000 and preferably 2000-5000 and most preferably of 3000-5000.

    [0058] Polyether polyols which may be used for preparing the isocyanate-terminated prepolymer include products obtained by the polymerisation of ethylene oxide with another cyclic oxide, for example propylene oxide or tetrahydrofuran in the presence of polyfunctional initiators. Suitable initiator compounds contain a plurality of active hydrogen atoms and include water and polyols, for example ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, cyclohexane dimethanol, resorcinol, bisphenol A, glycerol, trimethylolpropane, 1,2,6-hexanetriol or pentaerythritol. Mixtures of initiators and/or cyclic oxides may be used.

    [0059] Especially useful polyether polyols include poly(oxyethylene-oxypropylene) diols and triols obtained by the sequential addition of propylene and ethylene oxides to di- or trifunctional initiators as fully described in the prior art. Mixtures of the said diols and triols can be useful as well.

    [0060] The isocyanate-terminated prepolymer is prepared by reaction of an excessive amount of the polyisocyanate with the polyether polyol in order to obtain a prepolymer having the indicated NCO value. Methods to prepare prepolymers have been described in the art.

    [0061] The relative amounts of polyisocyanate and polyether polyol depend on their equivalent weights and on the desired NCO value and can be determined easily by those skilled in the art. If desired, the reaction may be conducted in the presence of catalysts which enhance the formation of urethane groups, like tertiary amines and tin compounds. In general the reaction time is between 30 minutes and 4 hours and the temperature between 50 and 90°C.

    [0062] At least 90% of the groups obtained by reacting the polyisocyanate with the polyether polyol for preparing the prepolymer are polyurethane groups. To the prepolymers so prepared a polyisocyanate may be added provided the NCO value remains in the indicated range. The amount added in general is less than 25% by weight based on the total polyisocyanate composition. The added polyisocyanate may be selected from those mentioned above. Aromatic polyisocyanates and in particular MDI based polyisocyanates are preferred.

    [0063] According to embodiments, the at least one polymer polyetherpolyol is selected from a filled polyether polyol having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol and is having an average ethylene oxide content of maximum 20 % by weight, preferably 10-20 % by weight, and wherein the ethylene oxide groups are present at the end of the polyether polyol (tipped).

    [0064] According to embodiments, the at least one polymer polyol is selected from a filled polyether polyol having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol and wherein said polymer polyol is a dispersion of polymer solid particles such as styrene based polymer particles in the polyol. Examples of styrene polymer particles include so-called "SAN" particles of styrene-acrylonitrile.

    [0065] According to a preferred embodiment, the at least one polymer polyetherpolyol is a mixture of polyols comprising a first polyether polyol and a second polyetherpolyol provided that the mixture is having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol mixture. The molecular weight of the mixture is preferably in the range 4000-7000. The first polyetherpolyol is preferably having a molecular weight in the range of 5000-7000 and an ethylene oxide content of 10-20 % by weight and wherein the ethylene oxide groups are present at the end of the polyether polyol (tipped). The second polyetherpolyol is preferably having a molecular weight in the range of 4000-6000, preferably around 5000 and an ethylene oxide content of 10-20 % by weight and wherein the ethylene oxide groups are present at the end of the polyether polyol (tipped). The ratio of first polyetherpolyol to the second polyetherpolyol is preferably in the range 20/80 up to 40/60. Suitable examples of the first polyetherpolyol in the polymer polyol include but are not limited to Hyperlite® 1650 (obtained from Bayer), KE® 885 (obtained from Konix), SPEC FLEX NC 700 (obtained from DOW).

    [0066] According to another preferred embodiment, the at least one polymer polyetherpolyol is a mixture op polyols comprising a first polyether polyol and a second polyetherpolyol provided that the mixture is having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol mixture. The molecular weight of the mixture is preferably in the range 2000-4000. The first polyetherpolyol is preferably having a molecular weight in the range of 1000-2000 and is preferably selected from polytetrahydrofuran (also called polytetramethylene ether glycol). The second polyetherpolyol is preferably having a molecular weight in the range of 4000-6000, preferably around 5000 and having an ethylene oxide content of 10-20 % by weight and wherein the ethylene oxide groups are present at the end of the polyether polyol (tipped). The ratio of first polyetherpolyol to the second polyetherpolyol is preferably in the range 80/20 up to 40/60. Suitable examples of the first polyetherpolyol in the polymer polyol include but are not limited to Terathane® from Invista and PolyTHF® from BASF.

    [0067] According to embodiments, blowing agents may be selected from fluor based hydrocarbon compounds (hydrofluorcarbon compounds) and/or alternatively from acetal based compounds and/or water. The blowing agents used may be a combination of aforementioned compounds.

    [0068] According to embodiments, the blowing agent may be a fluor based hydrocarbon compound. A suitable fluor based hydrocarbon compound is Forane ® 365 (available from Arkema). The amount of fluor based hydrocarbon compound (if used alone) is in the range 3-6 wt % calculated on the total weight of the reaction system.

    [0069] According to embodiments, the blowing agent may be an acetal based compound. A suitable acetal based compound is Methylal. The amount of acetal based compound as blowing agent (if used alone) is in the range 4-8 wt % calculated on the total weight of the reaction system.

    [0070] The amount of water used as foaming agent, preferably in the absence of other blowing agents, may be varied in known manner in order to achieve the desired density. Suitable amounts of water are generally at least 0.3 parts by weight, preferably from 0.3-1.3 parts by weight, per 100 parts of the reaction system. Preferably water is the sole blowing agent.

    [0071] The reaction system further may comprise conventional additives like catalysts, surfactants, colorants, stabilisers, fillers and mold release agents.

    [0072] Preferably the chain extenders and cross-linkers are polyols having an hydroxyl functionality of 2-6 and preferably 2-4 and a molecular weight of 62-499, like ethylene glycol, (mono) ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butane diol, glycerol, trimethylolpropane, hexanediol, pentaerythritol and polyethylene glycols of MW of 499 and less. The amount of chain extenders and cross-linker is at most 15 parts by weight per 100 parts by weight of polyol used to react with the polyisocyanate composition. More preferably the amount of chain extenders and cross-linker is preferably in the range 5-15 parts by weight per 100 parts by weight of polyol used to react with the polyisocyanate composition

    [0073] According to preferred embodiments, the chain extender is mono-ethyleneglycol (MEG), butanediol and/or hexanediol especially in case rotating moulding is applied.

    [0074] According to a second aspect of the invention the use of the reaction system for making the polyurethane elastomer according to the invention is disclosed. Said process comprises reacting at an isocyanate index in the range 90-110, preferably in the range 100-105 the reactive system according to the first aspect of the invention.

    [0075] Conventionally the polymer polyetherpolyol is premixed with the chain extenders, catalysts, blowing agents, and other additives and then reacted with the polyisocyanate composition.

    [0076] The use of the reaction system for making the polyurethane elastomer according to the invention comprises reacting the ingredients of the reaction system in a mould.

    [0077] According to embodiments, the use of the reaction system for making tires made of the polyurethane cellular elastomer according to the invention comprises at least the steps of:
    1. i. pre-mixing the polymer polyetherpolyol with the chain extenders, catalysts, blowing agents, and other additives, and
    2. ii. mixing the polyisocyanate composition with the pre-mixed polymer polyetherpolyol obtained in step i), and
    3. iii. casting the mixed polyisocyanate composition obtained in step ii) into a mould to obtain a reacted polyisocyanate composition, and then
    4. iv. curing the reacted polyisocyanate composition obtained in step iii) at an elevated temperature, and then
    5. v. demoulding the obtained tire made of polyurethane cellular elastomer.


    [0078] According to embodiments, the step of mixing of the polyisocyanate composition with the pre-mixed polymer polyetherpolyol obtained in step i) is performed using a 2 component high pressure mixing system.

    [0079] According to embodiments, the step of mixing of the polyisocyanate composition with the pre-mixed polymer polyetherpolyol obtained in step i) is performed using a 2 component dynamic mixing system.

    [0080] According to embodiments, the step of casting the mixed polyisocyanate composition obtained in step ii) is performed using an open mould, preferably a rotating open mould. The rotation speed may be in the range 150-350 rpm, a suitable rotation speed is 200rpm.

    [0081] According to embodiments, the step of curing the reacted polyisocyanate composition obtained in step iii) is performed at elevated temperatures in the range 50-60°C. Preferably the curing is performed in a furnace.

    [0082] According to embodiments, the moulding process is a rotation moulding process and the chain extender used is selected from mono-ethyleneglycol (MEG), butanediol and/or hexanediol.

    [0083] The invention is illustrated with the following examples.

    EXAMPLES


    Chemicals used:


    Water



    [0084] Forane 365 = blowing agent (Arkema)
    Oil = abrasion improver (Dow Corning)

    Catalyst A = Metal containing skin curing catalyst

    Catalyst B = Amine type gelling catalyst

    Catalyst C = Surfactant catalyst

    Catalyst D = Amine type curing catalyst

    Catalyst E = Amine type gelling catalyst

    Butanediol 1.4 = chain extender
    MonoEthyleneGlycol (MEG) = chain extender

    Polyether polyol A (triol) loaded with SAN particles, MW= 5000, 17 wt% EO

    Polyether polyol B (triol) MW=6000, 17 wt% EO

    Polyether polyol C (Polytetrahydrofurane) MW=2000

    Polyether polyol D (triol) MW = 4800, 15 wt% EO



    [0085] Isocyanate prepolymer Suprasec® 2733 (Huntsman) having NCO= 19.5 and which is reaction product of a 4.4 MDI based polyisocyanate and a polyetherpolyol with 20-35 wt% EO (all tipped) and having a number average MW in range 3000-4000.

    [0086] Isocyanate prepolymer Suprasec® 2021 (Huntsman) having NCO= 23.2 and which is reaction product of a 4.4 MDI based polyisocyanate and an ethylene oxide (EO) free polyetherpolyol having a number average MW below 500.

    Examples 1-2: preparation of cellular polyurethane elastomeric composition for making bicycle tires



    [0087] The reactive polyisocyanate composition was prepared by mixing the polymer polyol composition with the isocyanate prepolymer composition (index 104). Subsequently the reactive polyisocyanate composition was poured in an open rotating mould (200rpm) resulting in a bicycle tire. After 5 minutes curing at 50-60 °C in a furnace the solid casting was demoulded from the mould.

    [0088] Examples 1 and 2 are according to the invention, the comparative example is using a reactive composition according to the state of the art. Table 1 below shows the composition of the reactive systems, more in particular the polymer polyol composition and the isocyanate prepolymer composition used in pbw.

    [0089] All examples are resulting in cellular polyurethane elastomeric material (here a bicycle tire) having a (moulded) density around 500 kg/m3.
    Table 1
    Polymer polyol composition (pbw)% wt
    ComparativeExample 1Example 2
    Forane 365   4.52 -
    Water 0.45 - 0.52
    Oil   0.92 0.92
    Catalyst A 0.05 0.04 0.04
    Catalyst B 0.5 0.46 0.46
    Catalyst C 0.5 0.46 0.46
    Catalyst D   0.18 0.18
    Butanediol 1.4   8.46 8.46
    MonoEthyleneGlycol (MEG) 10    
    polyol A   65.63 65.63
    polyol B   19.33 19.33
    Polyol D 88.5    
    Isocyanate composition (Prepolymer)% wt
    S2733   100 100
    S2021 100    
    NCO 23.2 19.5 19.5
    Index 104 104 104


    [0090] Table 2 below shows the characteristics of the elastomer obtained by reacting the reactive composition according to Table 1 at an isocyanate index of 104.
    Table 2
    ParameterTest methodComparativeExample 1Example 2
    Abrasion (mg) DIN ISO 4649-02 309 59 51
    Compression Hardness @ 65% (KPa) DIN ISO 3386-1 1929.4 2885.2 2716.8
    Compression set at 70°C (%) ASTM D395 25.2 10.8 19.2
    Compression set at Room Temp ASTM D395 10 3.4 4.3
    Hardness Shore A ASTM D2240 62 69 73
    Resilience Rebound (% ball rebound) ASTM D3574 28 46 39

    Example 3: preparation of cellular polyurethane elastomeric composition using Polytetrahydrofurane based polymer polyols



    [0091] The reactive polyisocyanate composition was prepared by mixing the polymer polyol composition with the isocyanate prepolymer composition (index 104) using low pressure mixing. Subsequently the reactive polyisocyanate composition was poured in an open mould. After 5 minutes curing at 50-60 °C in a furnace the solid casting was demoulded from the mould.

    [0092] Example 3 is according to the invention, the comparative example is using a reactive composition according to the state of the art. Table 3 below shows the composition of the reactive systems, more in particular the polymer polyol composition and the isocyanate prepolymer composition used in pbw.
    Table 3
    Polymer Polyol composition (pbw)Comparative @ Shore A hardness 500Example 3a @ Shore A hardness 500Example 3b @ Shore A hardness 550Example 3c @ Shore A hardness 600
    Water 0.45 0.28 0.25 0.23
    Catalyst A 0.05 0.02 0.02 0.02
    Catalyst B 0.5      
    Catalyst C 0.5 0.5 0.5 0.5
    Catalyst E   0.1 0.1 0.1
    MonoEthyleneGlycol (MEG) 10 3 3 3
    polyol A   37.39 37.39 37.39
    polyol D 88.5      
    polyol C (PTHF)   58.75 58.75 58.75
     Isocyanate composition (Prepolymer)
    S2733   100 100 100
    S2021 100      
    NCO 23.2 19.5 19.5 19.5
    Index 104 104 104 104


    [0093] Table 4 below shows the characteristics of the elastomer obtained by reacting the reactive composition according to Table 1 at an isocyanate index of 104.
    Table 4
    ParameterTest methodComparativeExample 3a @ Shore A hardness 500Example 3b @ Shore A hardness 550Example 3c @ Shore A hardness 600
    Compression Hardness @ 65% (MPa) DIN ISO 3386-1 1.9 2.9 3.6 4.9
    Compression set at 70°C (%) ASTM D395 25.2 13 11 8
    Compression set at Room Temp ASTM D395 10 6 5 6
    Hardness Shore A ASTM D2240 62 49 51 52
    Resilience Rebound (% ball rebound) ASTM D3574 28 64 66 67

    Performance of bicycle tires made of the cellular polyurethane elastomer according to the invention



    [0094] The performance of tires made from cellular polyurethane elastomers according to the invention are compared with tires made from cellular polyurethane elastomers according to the state of the art.

    [0095] Cellular polyurethane elastomer tire 1 is a cellular polyurethane elastomer according to the present invention whereby the tire has a Shore A hardness of 70-75 (using reactive formulation for sample 2 in Table 1).

    [0096] Cellular polyurethane elastomer tire 2 is a cellular polyurethane elastomer according to the present invention whereby the tire has a Shore A hardness of 60-65 (using reactive formulation for sample 2 in Table 1 with the exception that the amount of butanediol is 7 pbw).

    [0097] Cellular polyurethane elastomer tire 3 is a cellular polyurethane elastomer according to the present invention whereby the tire has a Shore A hardness of 50 (using reactive formulation for sample 2 in Table 1 with the exception that the amount of butanediol is 5.5 pbw).

    [0098] The prior art cellular polyurethane elastomer tire 1 is a cellular polyurethane elastomer whereby the tire has a Shore A hardness of 75 (using reactive formulation for comparative example in Table 1).

    [0099] Table 5 illustrates the power performance for tires loaded with a total weight of 25, 50 and 100 kg and the power required to achieve a speed of 20 km/h.

    [0100] It can be concluded that the lower the power, the better (lower) the rolling resistance and hence the performance of the tire. An improvement of more than 20% is achieved when using the cellular polyurethane composition of the invention.
    Table 5
    Type of TireWeight (kg)Speed (km/h)Power (W)
    Cellular polyurethane elastomer tire 1 25 20 27.0
    50 20 61.3
    100 20 161.6
    cellular polyurethane elastomer tire 2 25 20 29.8
    50 20 64.7
    100 20 164.5
    cellular polyurethane elastomer tire 3 25 20 32.0
    50 20 70.8
    100 20 176.5
    Prior art cellular polyurethane elastomer tire 25 20 33.7
    50 20 75.8
    100 20 195.0



    Claims

    1. A reaction system for making a filled tire made of cellular polyurethane or polyurethane-urea elastomeric material, said reaction system comprising at least:

    - a polyisocyanate composition having a free NCO-value of 15-25% by weight comprising an isocyanate-terminated prepolymer which is the reaction product of an excess of an organic polyisocyanate and a polyether polyol having an average nominal hydroxyl functionality of 2-6, a number average molecular weight of 2000-6000 and an ethylene oxide content of 20-35% by weight, wherein at least 50% of the ethylene oxide groups are present at the end of the polyether polyol, and

    - a polyol composition comprising at least one polymer polyetherpolyol having a molecular weight in the range 2000-7000 and having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol; and

    - chain extenders and/or cross-linkers, and

    - catalysts, and

    - blowing agents


     
    2. A reaction system according to claim 1 wherein the organic polyisocyanate used in the preparation of the polyisocyanate composition is selected from aliphatic, cycloaliphatic and/or araliphatic polyisocyanates, preferably selected from aromatic polyisocyanates, more preferably from diphenylmethane diisocyanate (MDI) based polyisocyanates, most preferably diphenylmethane diisocyanate (MDI) based polyisocyanates having > 95 % wt 4,4'-MDI calculated on the total weight of the organic polyisocyanate mixture.
     
    3. A reaction system according to any of claims 1-2 wherein the polyether polyols used for preparing the prepolymer contain 20-35% by weight ethylene oxide groups wherein at least 50%, preferably at least 75% and more preferably all (100%) of these ethylene oxide groups are present at the end of the polyether polyol (tipped) and wherein said polyether polyols have an average nominal functionality of 2-6, preferably of 2-4, a number average molecular weight of 2000-6000 and preferably 2000-5000 and most preferably of 3000-5000.
     
    4. A reaction system according to any of claims 1-3 wherein the polyether polyols used for preparing the prepolymer are selected from poly(oxyethylene-oxypropylene) diols and triols..
     
    5. A reaction system according to any of claims 1-4 wherein the at least one polymer polyetherpolyol is selected from a filled polyether polyol having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol and is having an ethylene oxide content of maximum 20 % by weight, preferably in the range 10-20 % by weight and wherein the ethylene oxide groups are present at the end of the polyether polyol (tipped).
     
    6. A reaction system according to any of claims 1-5 wherein the at least one polymer polyetherpolyol is selected from a filled polyether polyol having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol and wherein said polymer polyetherpolyol is a dispersion of polymer solid particles such as styrene based polymer particles, preferably styrene-acrylonitrile particles.
     
    7. A reaction system according to any of claims 1-6 wherein the polyol composition comprising at least one polymer polyetherpolyol is a mixture of a first polyether polyol and a second polyetherpolyol having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol mixture and wherein

    - the first polyetherpolyol is having a molecular weight in the range of 5000-7000 and an ethylene oxide content of 10-20 % by weight and the ethylene oxide groups are present at the end of the polyether polyol (tipped), and

    - the second polyetherpolyol is having a molecular weight in the range of 4000-6000, preferably around 5000 and an ethylene oxide content of 10-20 % by weight and wherein the ethylene oxide groups are present at the end of the polyether polyol (tipped), and

    - the molecular weight of the mixture is preferably in the range 4000-7000 and wherein the ratio of the first polyetherpolyol to the second polyetherpolyol is preferably in the range 20/80 up to 40/60


     
    8. A reaction system according to any of claims 1-7 wherein the polyol composition comprising at least one polymer polyetherpolyol is a mixture of a first polyether polyol and a second polyetherpolyol having solid particles in the range of 15-35 wt % calculated on the total weight of the polyol mixture and wherein

    - the first polyetherpolyol is having a molecular weight in the range of 1000-2000 and is selected from polytetrahydrofuran, and

    - the second polyetherpolyol is having a molecular weight in the range of 4000-6000, preferably around 5000 and an ethylene oxide content of 10-20 % by weight and wherein the ethylene oxide groups are present at the end of the polyether polyol (tipped), and

    - the molecular weight of the mixture is preferably in the range 2000-4000 and wherein the ratio of the first polyetherpolyol to the second polyetherpolyol is preferably in the range 80/20 up to 40/60.


     
    9. A reaction system according to any of claims 1-8 wherein the blowing agents are selected from fluor based hydrocarbon compounds (hydrofluorcarbon compounds) and/or acetal based compounds and/or water.
     
    10. A reaction system according to any of claims 1-9 wherein the blowing agent is an acetal based compound such as methylal and is used preferably in the absence of other blowing agents in the range 4-8 wt % calculated on the total weight of the reaction system.
     
    11. A reaction system according to any of claims 1-10 wherein the blowing agent is water, preferably in the absence of other blowing agents, and is used in the range of at least 0.3 parts by weight, preferably from 0.3 to 1.3 parts by weight, per 100 parts of the reaction system.
     
    12. A reaction system according to any of claims 1-11 wherein the chain extenders and cross-linkers are polyols having an hydroxyl functionality of 2-6 and preferably 2-4 and a molecular weight of 62-499 such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butane diol, glycerol, trimethylolpropane, hexanediol, pentaerythritol and polyethylene glycols and wherein the amount of chain extenders and cross-linker is at most 15 parts by weight per 100 parts by weight of polyol used to react with the polyisocyanate composition, more preferably the amount of chain extenders and cross-linker is in the range 5-15 parts by weight per 100 parts by weight of polyol used to react with the polyisocyanate composition.
     
    13. A reaction system according to any of claims 1-12 wherein the chain extender is mono ethylene glycol, butanediol and/or hexanediol.
     
    14. Use of the reaction system according to any of claims 1-13 in a process for making a polyurethane elastomer , said process comprising reacting at an isocyanate index in the range 90-110, preferably in the range 100-105 the reactive system according to any of claims 1-13 in a mould.
     
    15. The use of the reaction system according to claim 14 wherein the polymer polyetherpolyol is premixed with the chain extenders, catalysts, blowing agents, and other additives and then reacted with the polyisocyanate composition.
     
    16. The use of the reaction system according to any of claims 14-15 wherein the process comprises at least the steps of:

    i. pre-mixing the polymer polyetherpolyol with the chain extenders, catalysts, blowing agents, and other additives, and then

    ii. mixing the polyisocyanate composition with the pre-mixed polymer polyetherpolyol obtained in step i) and then

    iii. casting the mixed polyisocyanate composition obtained in step ii) into a mould to obtain a reacted polyisocyanate composition, and then

    iv. curing the reacted polyisocyanate composition obtained in step iii) at an elevated temperature, and then

    v. demoulding the obtained tire made of polyurethane cellular elastomer.


     
    17. The use of the reaction system according to any of claims 14-16 wherein the step of mixing of the polyisocyanate composition with the pre-mixed polymer polyetherpolyol obtained in step i) is performed using a 2 component high pressure mixing system or a 2 component dynamic mixing system and wherein the step of casting the mixed polyisocyanate composition obtained in step ii) is performed using an open mould, preferably a rotating open mould at a rotation speed in the range 150-250 rpm and wherein the step of curing the reacted polyisocyanate composition obtained in step iii) is performed at elevated temperatures in the range 50-60 °C.
     
    18. A filled tire made of a cellular polyurethane or polyurethane-urea elastomeric material obtained using the reactive mixture according to any of claims 1-13, said elastomeric material having the following properties:

    - Shore A hardness according to ASTM D2240 of at least 45 and lower than 85, preferably in the range 45-80;

    - Compression set at room temperature lower than 10 % and at 70°C lower than 40 % according to ASTM D395;

    - Ball rebound according to ASTM D3574 of at least 40%, preferably from 40 to 70%;


     
    19. A tire according to claim 18, wherein the tire is a low speed vehicle tire such as a bicycle tire.
     
    20. A tire according to any of claim 18-19 wherein the cellular polyurethane elastomeric material is having a moulded density in the range 400-700 kg/m3, preferably in the range 500-600 kg/m3 and a free rise density in the range 250-350 kg/m3 preferably in the range 300-320 kg/m3 according to ISO 845.
     


    Ansprüche

    1. Reaktionssystem zur Herstellung eines gefüllten Reifens aus zelligem, elastomerem Polyurethan- oder Polyurethan-Harnstoff-Material, wobei das Reaktionssystem zumindest folgendes umfasst:

    - eine Polyisocyanatzusammensetzung mit einem freien NCO-Wert von 15 - 25 Gewichts-%, umfassend ein Isocyanat-terminiertes Präpolymer, das das Reaktionsprodukt eines Überschusses eines organischen Polyisocyanats und eines Polyetherpolyols mit einer mittleren nominalen Hydroxylfunktionalität von 2 - 6, einem Zahlenmittel des Molekulargewichts von 2000 - 6000 und einem Ethylenoxidgehalt von 20 - 35 Gewichts-% ist, wobei mindestens 50% der Ethylenoxidgruppen am Ende des Polyetherpolyols vorhanden sind, und

    - eine Polyolzusammensetzung, umfassend mindestens ein polymeres Polyetherpolyol mit einem Molekulargewicht im Bereich von 2000 - 7000 und mit festen Teilchen im Bereich von 15 - 35 Gew.-%, berechnet auf das Gesamtgewicht des Polyols; und

    - Kettenverlängerer und/oder Vernetzer und

    - Katalysatoren und

    - Treibmittel


     
    2. Reaktionssystem nach Anspruch 1, wobei das zur Herstellung der Polyisocyanatzusammensetzung verwendete organische Polyisocyanat ausgewählt ist aus aliphatischen, cycloaliphatischen und/oder araliphatischen Polyisocyanaten, bevorzugt ausgewählt aus aromatischen Polyisocyanaten, bevorzugter aus Polyisocyanaten auf Diphenylmethandiisocyanat (MDI)-Basis, am meisten bevorzugt Polyisocyanaten auf Diphenylmethandiisocyanat (MDI)-Basis mit > 95 Gew.-% 4,4'-MDI, berechnet auf das Gesamtgewicht der organischen Polyisocyanatmischung.
     
    3. Reaktionssystem nach irgendeinem der Ansprüche 1-2, wobei die zur Herstellung des Präpolymers verwendeten Polyetherpolyole 20-35 Gewichts-% Ethylenoxidgruppen enthalten, wobei mindestens 50%, bevorzugt mindestens 75% und bevorzugte alle (100%) dieser Ethylenoxidgruppen am Ende des Polyetherpolyols (endständig (tipped)) vorhanden sind und wobei die Polyetherpolyole eine durchschnittliche nominale Funktionalität von 2 - 6, bevorzugt von 2 - 4, ein Zahlenmittel des Molekulargewichts von 2000 - 6000 und bevorzugt von 2000 - 5000 und am meisten bevorzugt von 3000 - 5000 aufweisen.
     
    4. Reaktionssystem nach irgendeinem der Ansprüche 1-3, wobei die zur Herstellung des Präpolymers verwendeten Polyetherpolyole ausgewählt sind aus Poly(oxyethylenoxypropylen)diolen und -triolen.
     
    5. Reaktionssystem nach irgendeinem der Ansprüche 1-4, wobei das mindestens eine polymere Polyetherpolyol ausgewählt ist aus einem gefüllten Polyetherpolyol mit festen Teilchen im Bereich von 15 - 35 Gew.-%, berechnet auf das Gesamtgewicht des Polyols, und einen Ethylenoxidgehalt von maximal 20 Gewichts-%, bevorzugt im Bereich von 10 - 20 Gewichts-%, aufweist und wobei die Ethylenoxidgruppen am Ende des Polyetherpolyols (endständig) vorhanden sind.
     
    6. Reaktionssystem nach irgendeinem der Ansprüche 1-5, wobei das mindestens eine polymere Polyetherpolyol ausgewählt ist aus einem gefüllten Polyetherpolyol mit festen Teilchen im Bereich von 15 - 35 Gew.-%, berechnet auf das Gesamtgewicht des Polyols, und wobei das polymere Polyetherpolyol eine Dispersion von festen Polymerteilchen, wie z.B. Polymerteilchen auf Styrolbasis, bevorzugt Styrol-Acrylnitril-Teilchen, ist.
     
    7. Reaktionssystem nach irgendeinem der Ansprüche 1-6, wobei die Polyolzusammensetzung, die mindestens ein polymeres Polyetherpolyol umfasst, eine Mischung aus einem ersten Polyetherpolyol und einem zweiten Polyetherpolyol mit festen Teilchen im Bereich von 15 - 35 Gew.-%, berechnet auf das Gesamtgewicht der Polyolmischung, ist und wobei

    - das erste Polyetherpolyol ein Molekulargewicht im Bereich von 5000 - 7000 und einen Ethylenoxidgehalt von 10 - 20 Gewichts-% aufweist und die Ethylenoxidgruppen am Ende des Polyetherpolyols (endständig) vorhanden sind, und

    - das zweite Polyetherpolyol ein Molekulargewicht im Bereich von 4000 - 6000, bevorzugt etwa 5000, und einen Ethylenoxidgehalt von 10 - 20 Gewichts-% aufweist und wobei die Ethylenoxidgruppen am Ende des Polyetherpolyols (endständig) vorhanden sind und

    - das Molekulargewicht der Mischung bevorzugt im Bereich von 4000 - 7000 liegt und wobei das Verhältnis des ersten Polyetherpolyols zum zweiten Polyetherpolyol bevorzugt im Bereich von 20/80 bis zu 40/60 liegt.


     
    8. Reaktionssystem nach irgendeinem der Ansprüche 1-7, wobei die Polyolzusammensetzung, die mindestens ein polymeres Polyetherpolyol umfasst, eine Mischung aus einem ersten Polyetherpolyol und einem zweiten Polyetherpolyol mit festen Teilchen im Bereich von 15 - 35 Gew.-%, berechnet auf das Gesamtgewicht der Polyolmischung, ist und wobei

    - das erste Polyetherpolyol ein Molekulargewicht im Bereich von 1000 - 2000 aufweist und aus Polytetrahydrofuran ausgewählt ist und

    - das zweite Polyetherpolyol ein Molekulargewicht im Bereich von 4000 - 6000, bevorzugt etwa 5000, und ein Ethylenoxidgehalt von 10 - 20 Gewichts-% aufweist und wobei die Ethylenoxidgruppen am Ende des Polyetherpolyols (endständig) vorhanden sind, und

    - das Molekulargewicht der Mischung bevorzugt im Bereich von 2000 - 4000 liegt und wobei das Verhältnis von dem ersten Polyetherpolyol zum zweiten Polyetherpolyol bevorzugt im Bereich von 80/20 bis zu 40/60 liegt.


     
    9. Reaktionssystem nach irgendeinem der Ansprüche 1-8, wobei die Treibmittel aus Kohlenwasserstoffverbindungen auf Fluorbasis (Fluorkohlenwasserstoffverbindungen) und/oder Verbindungen auf Acetalbasis und/oder Wasser ausgewählt sind.
     
    10. Reaktionssystem nach irgendeinem der Ansprüche 1-9, wobei das Treibmittel eine Verbindung auf Acetalbasis, wie z.B. Methylal, ist und bevorzugt in Abwesenheit anderer Treibmittel im Bereich von 4 - 8 Gew.-%, berechnet auf das Gesamtgewicht des Reaktionsystems, verwendet wird.
     
    11. Reaktionssystem nach irgendeinem der Ansprüche 1-10, wobei das Treibmittel Wasser ist, bevorzugt in Abwesenheit anderer Treibmittel, und in einem Bereich von mindestens 0,3 Gewichtsteilen, bevorzugt von 0,3 bis 1,3 Gewichtsteilen, pro 100 Teilen des Reaktionssystems verwendet wird.
     
    12. Reaktionssystem nach irgendeinem der Ansprüche 1-11, wobei die Kettenverlängerer und Vernetzer Polyole mit einer Hydroxylfunktionalität von 2 - 6 und bevorzugt 2 - 4 und einem Molekulargewicht von 62 - 499 sind, wie z.B. Ethylenglycol, Diethylenglycol. Propylenglycol, Dipropylenglycol, Butandiol, Glycerin, Trimethylolpropan, Hexandiol, Pentaerythrit und Polyethylenglycole, und wobei die Menge an Kettenverlängerern und Vernetzungsmitteln höchstens 15 Gewichtsteile pro 100 Gewichtsteilen des Polyols, das zur Umsetzung mit der Polyisocyanatzusammensetzung verwendet wird, beträgt, bevorzugter liegt die Menge an Kettenverlängerern und Vernetzern im Bereich von 5 - 15 Gewichtsteilen pro 100 Gewichtsteilen Polyol, das zur Reaktion mit der Polyisocyanatzusammensetzung verwendet wird.
     
    13. Reaktionssystem nach irgendeinem der Ansprüche 1-12, wobei der Kettenverlängerer Monoethylenglycol, Butandiol und/oder Hexandiol ist.
     
    14. Verwendung des Reaktionssystems nach irgendeinem der Ansprüche 1-13 in einem Verfahren zur Herstellung eines Polyurethanelastomers, wobei das Verfahren das Umsetzen des reaktiven Systems nach irgendeinem der Ansprüche 1-13 in einer Form bei einem Isocyanat-Index im Bereich von 90 - 110, bevorzugt im Bereich von 100 - 105, umfasst.
     
    15. Verwendung des Reaktionssystems nach Anspruch 14, wobei das polymere Polyetherpolyol mit den Kettenverlängerern, Katalysatoren, Treibmitteln und anderen Additiven vorgemischt und dann mit der Polyisocyanatzusammensetzung umgesetzt wird.
     
    16. Verwendung des Reaktionssystems nach irgendeinem der Ansprüche 14-15, wobei das Verfahren mindestens die folgenden Schritte umfasst:

    i. Vormischen des polymeren Polyetherpolyols mit den Kettenverlängerern, Katalysatoren, Treibmitteln und anderen Additiven und dann

    ii. Mischen der Polyisocyanatzusammensetzung mit dem in Schritt i) erhaltenen vorgemischten polymeren Polyetherpolyol und dann

    iii. Gießen der in Schritt ii) erhaltenen gemischten Polyisocyanatzusammensetzung in eine Form, um eine umgesetzte Polyisocyanatzusammensetzung zu erhalten, und dann

    iv. Härten der in Schritt iii) erhaltenen umgesetzten Polyisocyanatzusammensetzung bei einer erhöhten Temperatur und dann

    v. Entformen des erhaltenen Reifens aus zelligem Polyurethan-Elastomer.


     
    17. Verwendung des Reaktionssystems nach irgendeinem der Ansprüche 14-16, wobei der Schritt des Mischens der Polyisocyanatzusammensetzung mit dem in Schritt i) erhaltenen vorgemischten polymeren Polyetherpolyol unter Verwendung eines 2-Komponenten-Hochdruckmischsystems oder eines dynamischen 2-Komponenten-Mischsystems durchgeführt wird und wobei der Schritt des Gießens der in Schritt ii) erhaltenen gemischten Polyisocyanatzusammensetzung unter Verwendung einer offenen Form, bevorzugt einer rotierenden offenen Form bei einer Drehzahl im Bereich von 150 - 250 U/min, durchgeführt wird und wobei der Schritt des Härtens der in Schritt iii) erhaltenen umgesetzten Polyisocyanatzusammensetzung bei erhöhten Temperaturen im Bereich von 50 - 60 °C durchgeführt wird.
     
    18. Gefüllter Reifen aus einem zelligen, elastomeren Polyurethan- oder Polyurethan-Harnstoff-Material, das unter Verwendung der reaktiven Mischung nach irgendeinem der Ansprüche 1-13 erhalten wird, wobei das elastomere Material die folgenden Eigenschaften aufweist:

    - Shore-A-Härte gemäß ASTM D2240 von mindestens 45 und weniger als 85, bevorzugt im Bereich 45 - 80;

    - Druckverformungsrest bei Raumtemperatur kleiner als 10% und bei 70 °C kleiner als 40% gemäß ASTM D395;

    - Kugelrückprall gemäß ASTM D3574 von mindestens 40%, bevorzugt von 40 bis 70%.


     
    19. Reifen nach Anspruch 18, wobei der Reifen ein Fahrzeugreifen für niedrige Geschwindigkeit, wie z.B. ein Fahrradreifen, ist.
     
    20. Reifen nach irgendeinem der Ansprüche 18-19, bei dem das zellige, elastomere Polyurethanmaterial eine Formteildichte im Bereich von 400 - 700 kg/m3, bevorzugt im Bereich von 500 - 600 kg/m3, und eine Free-Rise-Dichte im Bereich von 250 - 350 kg/m3, bevorzugt im Bereich von 300 - 320 kg/m3 gemäß ISO 845, aufweist.
     


    Revendications

    1. Système réactionnel pour préparer un pneu plein fait d'un matériau élastomère de polyuréthane-urée ou de polyuréthane alvéolaire, ledit système réactionnel comprenant au moins :

    - une composition de polyisocyanate ayant une teneur en groupes NCO libres de 15 à 25 % en poids, comprenant un prépolymère à terminaison isocyanate qui est le produit de réaction d'un excès d'un polyisocyanate organique et d'un polyéther-polyol ayant une fonctionnalité hydroxyle nominale moyenne de 2 à 6, une masse moléculaire moyenne en nombre de 2000 à 6000 et une teneur en oxyde d'éthylène de 20 à 35 % en poids, dans laquelle au moins 50 % des groupes oxyde d'éthylène sont présents à l'extrémité du polyéther-polyol, et

    - une composition de polyol comprenant au moins un polyéther-polyol polymère ayant une masse moléculaire située dans la plage allant de 2000 à 7000 et ayant des particules solides à raison de 15 à 35 % en poids calculés par rapport au poids total du polyol ; et

    - des agents d'allongement de chaîne et/ou de réticulation, et

    - des catalyseurs, et

    - des agents d'expansion.


     
    2. Système réactionnel selon la revendication 1, dans lequel le polyisocyanate organique utilisé dans la préparation de la composition de polyisocyanate est choisi parmi les polyisocyanates aliphatiques, cycloaliphatiques et/ou araliphatiques, de préférence choisi parmi les polyisocyanates aromatiques, mieux encore parmi les polyisocyanates à base de diisocyanate de diphénylméthane (MDI), tout spécialement les polyisocyanates à base de diisocyanate de diphénylméthane (MDI) ayant plus de 95 % en poids de 4,4'-MDI, calculés par rapport au poids total du mélange de polyisocyanates organiques.
     
    3. Système réactionnel selon l'une quelconque des revendications 1 et 2, dans lequel les polyéther-polyols utilisés pour la préparation du prépolymère contiennent 20 à 35 % en poids de groupes oxyde d'éthylène, parmi lesquels au moins 50 %, de préférence au moins 75 % et mieux encore la totalité (100 %) de ces groupes oxyde d'éthylène sont présents à l'extrémité du polyéther-polyol (en pointe), et dans lequel lesdits polyéther-polyols ont une fonctionnalité nominale moyenne de 2 à 6, de préférence de 2 à 4, une masse moléculaire moyenne en nombre de 2000 à 6000 et de préférence de 2000 à 5000 et tout spécialement de 3000 à 5000.
     
    4. Système réactionnel selon l'une quelconque des revendications 1 à 3, dans lequel les polyéther-polyols utilisés pour la préparation du prépolymère sont choisis parmi les poly(oxyéthylène-oxypropylène)diols et triols.
     
    5. Système réactionnel selon l'une quelconque des revendications 1 à 4, dans lequel l'au moins un polyéther-polyol polymère est choisi parmi un polyéther-polyol chargé ayant des particules solides à raison de 15 à 35 % en poids, calculés par rapport au poids total du polyol, et a une teneur en oxyde d'éthylène au maximum de 20 % en poids, de préférence située dans la plage allant de 10 à 20 % en poids, et dans lequel les groupes oxyde d'éthylène sont présents à l'extrémité du polyéther-polyol (en pointe).
     
    6. Système réactionnel selon l'une quelconque des revendications 1 à 5, dans lequel l'au moins un polyéther-polyol polymère est choisi parmi un polyéther-polyol chargé ayant des particules solides à raison de 15 à 35 % en poids, calculés par rapport au poids total du polyol, et dans lequel ledit polyéther-polyol polymère est une dispersion de particules solides de polymère telles que des particules de polymère à base de styrène, de préférence des particules de styrène-acrylonitrile.
     
    7. Système réactionnel selon l'une quelconque des revendications 1 à 6, dans lequel la composition de polyol comprenant au moins un polyéther-polyol polymère est un mélange d'un premier polyéther-polyol et d'un deuxième polyéther-polyol ayant des particules solides à raison de 15 à 35 % en poids calculés par rapport au poids total du mélange de polyols, et dans lequel

    - le premier polyéther-polyol a une masse moléculaire située dans la plage allant de 5000 à 7000 et une teneur en oxyde d'éthylène de 10 à 20 % en poids et les groupes oxyde d'éthylène sont présents à l'extrémité du polyéther-polyol (en pointe), et

    - le deuxième polyéther-polyol a une masse moléculaire située dans la plage allant de 4000 à 6000, de préférence d'environ 5000, et une teneur en oxyde d'éthylène de 10 à 20 % en poids, et dans lequel les groupes oxyde d'éthylène sont présents à l'extrémité du polyéther-polyol (en pointe), et

    - la masse moléculaire du mélange est de préférence située dans la plage allant de 4000 à 7000, et dans lequel le rapport du premier polyéther-polyol au deuxième polyéther-polyol est de préférence situé dans la plage allant de 20/80 à 40/60.


     
    8. Système réactionnel selon l'une quelconque des revendications 1 à 7, dans lequel la composition de polyol comprenant au moins un polyéther-polyol polymère est un mélange d'un premier polyéther-polyol et d'un deuxième polyéther-polyol ayant des particules solides à raison de 15 à 35 % en poids calculés par rapport au poids total du mélange de polyols, et dans lequel

    - le premier polyéther-polyol a une masse moléculaire située dans la plage allant de 1000 à 2000 et est choisi parmi le polytétrahydrofurane, et

    - le deuxième polyéther-polyol a une masse moléculaire située dans la plage allant de 4000 à 6000, de préférence d'environ 5000, et une teneur en oxyde d'éthylène de 10 à 20 % en poids, et dans lequel les groupes oxyde d'éthylène sont présents à l'extrémité du polyéther-polyol (en pointe), et

    - la masse moléculaire du mélange est de préférence située dans la plage allant de 2000 à 4000, et dans lequel le rapport du premier polyéther-polyol au deuxième polyéther-polyol est de préférence situé dans la plage allant de 80/20 à 40/60.


     
    9. Système réactionnel selon l'une quelconque des revendications 1 à 8, dans lequel les agents d'expansion sont choisis parmi les composés hydrocarbonés à base de fluor (composés hydrofluorocarbonés) et/ou les composés à base d'acétal et/ou l'eau.
     
    10. Système réactionnel selon l'une quelconque des revendications 1 à 9, dans lequel l'agent d'expansion est un composé à base d'acétal tel que le méthylal et est utilisé de préférence en l'absence d'autres agents d'expansion à raison de 4 à 8 % en poids calculés par rapport au poids total du système réactionnel.
     
    11. Système réactionnel selon l'une quelconque des revendications 1 à 10, dans lequel l'agent d'expansion est l'eau, de préférence en l'absence d'autres agents d'expansion, et est utilisé à raison d'au moins 0,3 partie en poids, de préférence de 0,3 à 1,3 partie en poids pour 100 parties du système réactionnel.
     
    12. Système réactionnel selon l'une quelconque des revendications 1 à 11, dans lequel les agents d'allongement de chaîne et de réticulation sont des polyols ayant une fonctionnalité hydroxyle de 2 à 6 et de préférence de 2 à 4 et une masse moléculaire de 62 à 499, tels que l'éthylèneglycol, le diéthylèneglycol, le propylèneglycol, le dipropylèneglycol, le butanediol, le glycérol, le triméthylolpropane, l'hexanediol, le pentaérythritol et les polyéthylèneglycols, et dans lequel la quantité des agents d'allongement de chaîne et de réticulation est d'au plus 15 parties en poids pour 100 parties en poids du polyol utilisé pour réagir avec la composition de polyisocyanate, mieux encore la quantité des agents d'allongement de chaîne et de réticulation est située dans la plage allant de 5 à 15 parties en poids pour 100 parties en poids du polyol utilisé pour réagir avec la composition de polyisocyanate.
     
    13. Système réactionnel selon l'une quelconque des revendications 1 à 12, dans lequel l'agent d'allongement de chaîne est le monoéthylèneglycol, le butanediol et/ou l'hexanediol.
     
    14. Utilisation du système réactionnel de l'une quelconque des revendications 1 à 13 dans un procédé pour produire un élastomère de polyuréthane, ledit procédé comprenant la réaction, à un indice d'isocyanate situé dans la plage allant de 90 à 110, de préférence dans la plage allant de 100 à 105, du système réactif de l'une quelconque des revendications 1 à 13 dans un moule.
     
    15. Utilisation du système réactionnel selon la revendication 14, dans laquelle le polyéther-polyol polymère est pré-mélangé avec les agents d'allongement de chaîne, les catalyseurs, les agents d'expansion, et d'autres additifs, et ensuite mis à réagir avec la composition de polyisocyanate.
     
    16. Utilisation du système réactionnel selon l'une quelconque des revendications 14 et 15, dans laquelle le procédé comprend au moins les étapes consistant à :

    i. pré-mélanger le polyéther-polyol polymère avec les agents d'allongement de chaîne, les catalyseurs, les agents d'expansion, et d'autres additifs, et ensuite

    ii. mélanger la composition de polyisocyanate avec le polyéther-polyol polymère pré-mélangé obtenu dans l'étape i), et ensuite

    iii. couler la composition de polyisocyanate mélangée obtenue dans l'étape ii) dans un moule pour obtenir une composition de polyisocyanate ayant réagi, et ensuite

    iv. durcir la composition de polyisocyanate ayant réagi obtenue dans l'étape iii) à une température élevée, et ensuite

    v. démouler le pneu obtenu fait de l'élastomère alvéolaire de polyuréthane.


     
    17. Utilisation du système réactionnel selon l'une quelconque des revendications 14 à 16, dans laquelle l'étape consistant à mélanger la composition de polyisocyanate avec le polyéther-polyol polymère pré-mélangé obtenu dans l'étape i) est effectuée par utilisation d'un système de mélange sous pression élevée à 2 composants ou un système de mélange dynamique à 2 composants, et dans laquelle l'étape consistant à couler la composition de polyisocyanate mélangée obtenue dans l'étape ii) est effectuée par utilisation d'un moule ouvert, de préférence d'un moule ouvert rotatif à une vitesse de rotation située dans la plage allant de 150 à 250 tr/min, et dans laquelle l'étape consistant à durcir la composition de polyisocyanate ayant réagi obtenue dans l'étape iii) est effectuée à des températures élevées situées dans la plage allant de 50 à 60°C.
     
    18. Pneu plein fait d'un matériau élastomère de polyuréthane-urée ou de polyuréthane alvéolaire obtenu par utilisation du mélange réactif de l'une quelconque des revendications 1 à 13, ledit matériau élastomère ayant les propriétés suivantes :

    - une dureté Shore A conformément à la norme ASTM D2240 d'au moins 45 et inférieure à 85, de préférence située dans la plage allant de 45 à 80 ;

    - une déformation rémanente après compression à température ambiante inférieure à 10 % et à 70°C inférieure à 40 % conformément à la norme ASTM D395 ;

    - un rebond de balle conformément à la norme ASTM D3574 d'au moins 40 %, de préférence de 40 à 70 %.


     
    19. Pneu selon la revendication 18, lequel pneu est un pneu pour véhicule à basse vitesse tel qu'un pneu de bicyclette.
     
    20. Pneu selon l'une quelconque des revendications 18 et 19, dans lequel le matériau élastomère de polyuréthane alvéolaire a une masse volumique à l'état moulé située dans la plage allant de 400 à 700 kg/m3, de préférence dans la plage allant de 500 à 600 kg/m3, et une masse volumique en expansion libre située dans la plage allant de 250 à 350 kg/m3, de préférence dans la plage allant de 300 à 320 kg/m3, conformément à la norme ISO 845.
     






    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description