(19)
(11)EP 2 776 483 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
07.08.2019 Bulletin 2019/32

(21)Application number: 11877781.2

(22)Date of filing:  22.12.2011
(51)International Patent Classification (IPC): 
C08G 18/10(2006.01)
C08L 75/04(2006.01)
C08F 283/00(2006.01)
C08G 18/66(2006.01)
C08G 18/08(2006.01)
C08G 18/32(2006.01)
C08G 18/42(2006.01)
C08G 18/62(2006.01)
C09D 175/04(2006.01)
C08G 18/48(2006.01)
C08F 290/06(2006.01)
C08G 18/12(2006.01)
C08G 18/34(2006.01)
(86)International application number:
PCT/CN2011/084416
(87)International publication number:
WO 2013/091209 (27.06.2013 Gazette  2013/26)

(54)

PROCESS FOR MAKING CROSSLINKABLE POLYURETHANE/ACRYLIC HYBRID DISPERSIONS

VERFAHREN ZUR HERSTELLUNG VERNETZBARER HYBRIDER POLYURETHANELASTOMER-/ACRYL-DISPERSIONEN

PROCÉDÉ POUR LA PRÉPARATION DE DISPERSIONS HYBRIDES DE POLYURÉTHANE/ACRYLIQUE RÉTICULABLES


(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

(43)Date of publication of application:
17.09.2014 Bulletin 2014/38

(73)Proprietors:
  • Dow Global Technologies LLC
    Midland, MI 48674 (US)
  • Rohm and Haas Company
    Philadelphia, PA 19106 (US)

(72)Inventors:
  • ZHANG, Jiguang
    Shanghai 201204 (CN)
  • GUO, Shouxue
    Shanghai 201208 (CN)
  • WANG, Yujiang
    Shanghai 201615 (CN)
  • FENG, Shaoguang
    Shanghai 200126 (CN)
  • JIANG, Siyuan
    Shanghai 200129 (CN)
  • WANG, Caifeng
    Shanghai 201100 (CN)

(74)Representative: Houghton, Mark Phillip et al
Patent Outsourcing Limited 1 King Street
Bakewell, Derbyshire DE45 1DZ
Bakewell, Derbyshire DE45 1DZ (GB)


(56)References cited: : 
EP-A1- 1 391 471
CN-A- 1 880 374
US-A1- 2004 167 252
WO-A2-2011/123492
CN-A- 101 792 570
  
     
    Remarks:
    The file contains technical information submitted after the application was filed and not included in this specification
     
    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



    [0001] The invention relates to a process for making crosslinkable Polyurethane/Acrylic (PUA) hybrid dispersions, specifically, it relates to a chemical hybrid method for preparing stable crosslinkable PUA hybrid dispersions and the crosslinkable PUA hybrid dispersions produced by this process.

    Background



    [0002] Over recent decades, there has been a concerted effort to reduce atmospheric pollution caused by volatile solvents which are emitted during painting processes. Due to environmental concerns, volatile organic compounds (VOCs) have come under strict regulation by the government. Therefore, one of the major goals of the coating industry is to minimize the use of organic solvents by formulating waterborne coating compositions which provide a smooth, high gloss appearance, as well as good physical properties including resistance to acid rain. While the solvent-type coatings provide many benefits, such as that they are fast-drying, have a high hardness, a high abrasion-resistance, a high water-resistance, a high chemical-resistance and a low price, the waterborne coatings have environment-friendly benefits in that they are not flammable or explosive. The waterborne coatings use water as the system solvent and contain no poisonous chemicals. They require no or low amounts of volatile organic compounds.

    [0003] The unique advantage of polyurethane dispersions (PUDs) in relation to surface coatings is their ability to form coherent film and to control the microphase morphology by controlling the relative amounts of soft and hard segments in polymer chain. These features allow PUDs to be employed in a wide variety of surface coating applications where mechanical properties are particularly crucial. High abrasion resistance, superior toughness, elastomeric properties, and high extensibility at low temperature are typical benefits. However, relatively high raw material cost in comparison with a typical acrylic emulsion has restricted its use in many industrial applications. To overcome this, polyurethane dispersions have been combined with other relatively inexpensive polymers to obtain a cost/performance balance because the properties of polyurethane (PU) and the polyacrylate (PA) complement each other. The composite materials of PU and PA are more outstanding in terms of adhesion, film-formability, non-stickiness, weather-resistance, elongation and strength of the film with excellent cost-performance balance. Accordingly, since the development of PU, the modification of the PU by the PA has been an active research topic in the art.

    [0004] Two methods can be used to modify PU with PA: physical methods and chemical methods. The physical method is achieved by mechanical mixing. In the physical method, aqueous PA and PU dispersions (emulsions) are independently prepared first, and then both dispersions are mixed together under mechanical power. It is a very convenient method that makes it easy to control the composition of the final product. However, in such blends the superior performance properties may be compromised because of the incompatibility of the two. Such blended dispersion may suffer from instability.

    [0005] For these reasons, the chemical modification technology currently plays a more important role. The chemical method is achieved by post-polymerization of acrylates. In the chemical method, the PU dispersion can be prepared first, and then acrylates and other vinyl monomers can be polymerized in the PU dispersion. In most cases, core-shell emulsion polymerization is adopted. PU particles are used as seed particles and the acrylates are polymerized within the PU particles due to high hydrophobicity of the acrylates. These hybrid dispersions are expected to provide the advantages of PA, such as excellent weather resistance, affinity to pigments as well as lower cost, and the advantages of PU, such as better mechanical stability, excellent adhesion, solvent and chemical resistance, and toughness.

    [0006] U.S. Patent Application No.: 2009/0111934 A1 to Caideng Yuan discloses methods for the preparation of an aqueous PA modified PU dispersion, which includes three main steps: a) preparation of PA polymer or copolymer dispersion; b) preparation of PU prepolymer with carboxylic groups and neutralization treatment to the carboxylic groups; and c) dispersion and chain-extension of PU prepolymer by adding the PA dispersion into the PU prepolymer under vigorous agitation, or other mechanical operation. The result hybrid dispersion can be self-crosslinked by reaction between acetoacetoxy compound on PA particle and amine group on PU dispersion particles. A solvent, N-methyl-2-pyrrolidinone (NMP, b.p. 202∼204°C) was used as during the PU dispersion synthesis process. The use of NMP raises environmental concerns.

    [0007] U.S. Publication No. 2004/0034146 discloses a complicated solvent free process for preparing hybrid PUA. The PU prepolymer was NCO free and there is no chain extension step in water. The viscosity of the PU prepolymer could be too high to be well dispersed into water. Additionally, dimethylol propane acid (DMPA) was used as an acid containing diol which provides water-dispersity of the PUA dispersion. However, DMPA is hard to dissolve completely, so that the final prepolymer may still contain particulate DMPA and the reaction was not complete.

    [0008] EP1391471A1, of which US 2004/0034146 A1 is an equivalent, discloses a process for preparing aqueous, emulsifier-free and solvent free polyurethane-polyacrylate hybrid dispersions and polyurethane-polyacrylate hybrid dispersions obtained by such a process.

    [0009] CN1880374 A1 discloses an acrylic polyurethane water dispersible resin and a method for making same. The method involves firstly producing NCO capping polyurethane prepolymer with the ethenyl monomer part of which can be freely polymerized as medium, secondly obtaining a water-dispersible polyurethane coated with ethenyl monomers after neutralization and water dispersion, then adding in the rest of the ethenyl monomer and initiator to perform a free radical polymerization that produces the desired acrylic polyurethane water-dispersible resin.

    [0010] US2004/0167252 A1 discloses a process for preparing polyurethane-polyacrylate hybrid secondary dispersions and dispersions made by that process. The process involves preparing a polyurethane that contains no polymerisable double bonds, adding one or more certain vinylically unsaturated monomers, neutralising at least some of the neutralisable groups, and dispersing the hybrid polymer into the aqueous phase, wherein the neutralization can take place before or after the vinyl polymerization or during the dispersing step, and the polyurethane is prepared by reacting polyisocyanates with at least one compound that contains NCO-reactive groups.

    [0011] The present inventors have solved the problem of inhomogeniety of the reaction system and have provided processes for preparing PUAs with superior mechanical performance, such as elongation, and tensile strength. The process is solvent free, smooth, and robust. PU prepolymer prepared according to the present invention has low viscosity, and contains no particulate DMPA.

    Summary



    [0012] The invention is set out in accordance with the appended claims. The present invention provides processes for making polyurethane/acrylic hybrid dispersions comprising: i) adding at least one polyol to a reactor; ii) adding DMPA simultaneously with/after step i), but before step iii), as water dispersibility enhancing agent at a temperature of from 115°C to 140°C to obtain a homogeneous solution; iii) adding at least one polyisocyanate at a temperature of from 75°C to 95°C until the NCO content reaches a constant value to prepare the polyurethane prepolymer; iv) adding at least one acrylate monomer, at least one styrenic monomer, or the mixture thereof, as diluent to the polyurethane prepolymer, at a temperature of from 40°C to 65°C; v) adding a neutralizing agent; vi) dispersing and extending the polyurethane prepolymer in the presence of the acrylate monomer, and/or the styrenic monomer of step iv); and vii) adding at least one ethylenically unsaturated nonionic monomer, and co-polymerizing the same with the acrylate monomer, and/or the styrenic monomer of step iv), to get the polyurethane/acrylic hybrid dispersion. The process is continuous.

    [0013] The present invention further provides processes for making polyurethane/acrylic hybrid dispersions comprising cold-blending the polyurethane/acrylic hybrid dispersions of the present invention with polyacrylate dispersion under agitation. Optionally, the polyurethane/acrylic hybrid dispersion and polyacrylate dispersion are both modified by copolymerization with diacetone acrylamide (DAAm) or acetoacetoxyethyl methacrylate (AAEM).

    [0014] Further, adipic acid dihydrazide, as crosslinker, may be added into the blend.

    [0015] The present invention further provides the polyurethane/acrylic hybrid dispersions prepared thereof.

    [0016] The present invention further provides a coating composition comprising the polyurethane/acrylic hybrid dispersion prepared thereof.

    Detailed Description



    [0017] In the present invention, the term "polyurethane" or "PU" describes polymers including oligomers (e.g., prepolymers) which contain multiple urethane groups, i.e., -O-C(=O)-NH-, regardless of how they are made. As is well known, polyurethanes can contain additional groups such as urea, allophanate, biuret, carbodiimide, oxazolidinyl, isocyanurate, uretdione, ether, ester or carbonate, in addition to urethane groups. Typically, the prepolymers will be above 1,000 or 2,000 Daltons in number average molecular weight and if the chain is extended during processing, can reach number average molecular weights in the millions of Daltons.

    [0018] The term "polyacrylate" or "PA" as used herein means those polymers or resins resulting from the polymerization of one or more acrylates such as, for example, methyl acrylate, ethyl acrylate, butyl acrylate or 2-ethylhexyl acrylate, as well as the methacrylates such as, for instance, methyl methacrylate, ethyl methacrylate, butyl methacrylate or hexyl methacrylate. Copolymers of the above acrylate and methacrylate monomers are also included within the term "polyacrylate" as it appears herein. The polymerization of the monomeric acrylates and methacrylates to provide the PA dispersions useful in the practice of the invention may be accomplished by any of the well-known polymerization techniques.

    [0019] PUA in this invention is prepared by a) PU prepolymer preparation; b) dispersing and extending PU prepolymer in water; and c) adding and polymerizing at least one ethylenically unsaturated nonionic monomer(s).

    [0020] In a), PU prepolymer preparation of the present invention is conducted under decreasing temperature. Polyol(s) is added into the reaction vessel (the system) under N2 purging and the system is heated to a high temperature, preferably from 115°C to 140°C, more preferably from 120°C to 130°C. DMPA, as a water-dispersibility enhancing agent is simultaneously or later added into the system under mild stirring until a homogeneous solution is obtained. System temperature is lowered to 75°C - 95°C, more preferably from 80°C to 85°C. Polyisocyanate(s) is then added into the system, and the reaction proceeds until the NCO content reaches a constant value. After that, temperature is lowered further to from 40°C to 65°C, more preferably from 55°C to 60°C, and at least one acrylate monomer(s), at least one styrenic monomer(s), or the mixture thereof is added as reactive diluent or so called solvent. The weight ratio of acrylate and/or styrenic monomers in the total weight of prepolymer could range from 10 wt.% to 50 wt.%, preferably from 10 wt.% to 30 wt.%. Following that, triethyl amine (TEA) as neutralizing agent is added. The molar ratio of TEA to DMPA ranges from 0.9:1 to 1.1:1, preferably from 0.9:1 to 1:1.

    [0021] In b), after a short (several minutes, such as, from 5 to 15 minutes) mixing time, the prepolymer is gradually poured into DI water under agitation to form a dispersion. Several minutes later, chain extender with a molar ratio to NCO as 0.9:1 to 1.1:1, preferably from 0.9:1 to 1:1 is added dropwise to above dispersion.

    [0022] Then, ethylenically unsaturated nonionic monomer(s) is added into the system as polymerization unit. The total amount of ethylenically unsaturated nonionic monomer(s) is from 10 wt.% to 80 wt.%, preferably from 30 wt.% to 50 wt.% basing on the total weight of the PUA polymer.

    [0023] The dispersing b) can alternatively be conducted by pouring the PU prepolymer into a PA dispersion under agitation followed by chain extension.

    [0024] In c), at least one ethylenically unsaturated nonionic monomer(s) is added and then polymerized via radical polymerization in the presence of initiator and at elevated temperature.

    [0025] Optionally, the PUA dispersion prepared according to the above process can be mixed with PA dispersion under agitation.

    [0026] Optionally, the PUA dispersion and PA dispersion are separately modified by copolymerization with diacetone-based monomer, preferably, with DAAm or AAEM and other acrylate monomer(s). The amount of DAAm or AAEM is around 1 to 3 wt%, based on the total weight of monomers used to make the acrylic/styrenic portion of PUA.

    [0027] Adipic acid dihydrazide (ADH), as crosslinker, may be added into to the blend of PUA and PA dispersions. The content of polyacrylate, including those in both PA and PUA, may range from 10 wt.% to 80 wt.% in the total weight based on the total solids of PA and PUA.

    [0028] Polyols, including polyether diols, polyester diols or multi-functional polyols, are used to prepare the PU prepolymer. "Polyols" means any product having two or more hydroxyl groups per molecule. Examples of the polyols useful herein include polyether polyols, polyester polyols such as alkyds, polycarbonate polyols, polyhydroxy polyester amides, hydroxyl-containing polycaprolactones, hydroxyl-containing acrylic polymers, hydroxyl-containing epoxides, polyhydroxy polycarbonates, polyhydroxy polyacetals, polyhydroxy polythioethers, polysiloxane polyols, ethoxylated polysiloxane polyols, polybutadiene polyols and hydrogenated polybutadiene polyols, polyisobutylene polyols, polyacrylate polyols, polyols derived from halogenated polyesters and polyethers, and mixtures thereof. The polyether polyols, polyester polyols, and polycarbonate polyols or mixtures thereof are preferred.

    [0029] The polyether polyols that can be used as the active hydrogen-containing compound according to the present invention contain the --C--O--C-- group. They can be obtained in a known manner by the reaction of starting compounds that contain reactive hydrogen atoms such as water or diols, and alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin and mixtures thereof. Preferred polyethers include poly(propylene glycol) with molecular weight of 400 to 3000, polytetrahydrofuran and copolymers of poly(ethylene glycol) and poly(propylene glycol). The diols used in the preparation of the polyether polyols include alkylene glycols, preferably ethylene glycol, diethylene glycol and butylene glycol.

    [0030] The polyester polyols are typically esterification products prepared by the reaction of organic polycarboxylic acids or their anhydrides with a stoichiometric excess of a diol or diols. Examples of suitable polyols for use in the reaction include poly(glycol adipate), poly(ethylene terephthalate) polyols, polycaprolactone polyols, alkyd polyols, orthophthalic polyols, sulfonated and phosphonated polyols, and mixtures thereof. The diols used in making the polyester polyols are as set forth for preparing the polyether polyols. Suitable carboxylic acids used in making the polyester polyols include, dicarboxylic acids, tricarboxylic acids and anhydrides, e.g., maleic acid, maleic anhydride, succinic acid, glutaric acid, glutaric anhydride, adipic acid, suberic acid, pimelic acid, azelaic acid, sebacic acid, chlorendic acid, 1,2,4-butane-tricarboxylic acid, phthalic acid, the isomers of phthalic acid, phthalic anhydride, fumaric acid, dimeric fatty acids such as oleic acid, and mixtures thereof. Preferred polycarboxylic acids used in making the polyester polyols include aliphatic and/or aromatic dibasic acids.

    [0031] Particularly interesting polyols are the polyester diols containing -C(=O)-O-group. Examples include poly(butanediol adipate), caprolactones, acid-containing polyols, polyesters made from hexane diol, adipic acid and isophthalic acid such as hexane adipate isophthalate polyester, hexane diol neopentyl glycol adipic acid polyester diols, as well as propylene glycol maleic anhydride adipic acid polyester diols, and hexane diol neopentyl glycol fumaric acid polyester diols.

    [0032] Polyisocyanates have two or more isocyanate groups on average, preferably two to four isocyanate groups per molecule. Polyisocyanates typically comprise about 5 to 20 carbon atoms and include aliphatic, cycloaliphatic, aryl-aliphatic, and aromatic polyisocyanates, as well as products of their oligomerization, used alone or in mixtures of two or more. Diisocyanates are preferred. Toluene diisocyanate, hexamethylene isocyanate and/or isophorone isocyanate may preferably be used in the embodiment of the present invention.

    [0033] Examples of suitable aliphatic polyisocyanates include alpha, omega-alkylene diisocyanates having from 5 to 20 carbon atoms, such as hexamethylene-1,6-diisocyanate, 1,12-dodecane diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, 2,4,4-trimethyl-hexamethylene diisocyanate, 2-methyl-1,5-pentamethylene diisocyanate. Preferred aliphatic polyisocyanates include hexamethylene-1,6-diisocyanate, 2,2,4-trimethyl-hexamethylenediisocyanate, and 2,4,4-trimethyl-hexamethylene diisocyanate.

    [0034] Examples of suitable cycloaliphatic polyisocyanates include dicyclohexylmethane diisocyanate (commercially available as Desmodur™ from Bayer Corporation), isophorone diisocyanate, 1,4-cyclohexane diisocyanate and 1,3-bis-(isocyanatomethyl)cyclohexane. Preferred cycloaliphatic polyisocyanates include dicyclohexylmethane diisocyanate and isophorone diisocyanate.

    [0035] Examples of suitable araliphatic polyisocyanates include m-tetramethyl xylylene diisocyanate, p-tetramethyl xylylene diisocyanate, 1,4-xylylene diisocyanate and 1,3-xylylene diisocyanate. A preferred araliphatic polyisocyanate is tetramethyl xylylene diisocyanate.

    [0036] Examples of suitable aromatic polyisocyanates include 4,4'-diphenylmethylene diisocyanate, toluene diisocyanate, their isomers, naphthalene diisocyanate, and their oligomeric forms. A preferred aromatic polyisocyanate is toluene diisocyanate.

    [0037] The PU prepolymer may be formed without using a catalyst if desired, but using a catalyst may be preferred in some embodiments of the present invention. Examples of suitable catalysts include stannous octoate, dibutyl tin dilaurate, and tertiary amine compounds such as triethylamine and bis-(dimethylaminoethyl)ether, morpholine compounds, bismuth carboxylate, zinc bismuth carboxylate and diazabicyclo[2.2.2]octane. Organic tin catalysts are preferred.

    [0038] In the present invention, organic solvents are preferably not used, so the solvent-removing stage is omitted.

    [0039] Chain extenders used in the preparation of the PU dispersion are employed in the dispersion step b). Examples of chain extenders useful in this regard include any of inorganic or organic polyamines having an average of about 2 or more primary and/or secondary amine groups, amine functional polyols, ureas, or combinations thereof, and their mixtures. Suitable organic amines for use as a chain extender include, but are not limited to, diethylene triamine (DETA), ethylene diamine (EDA), meta-xylylenediamine (MXDA), aminoethyl ethanolamine (AEEA), 2-methyl pentane diamine, and mixtures thereof. Also suitable for the present invention are propylene diamine, butylene diamine, hexamethylene diamine, cyclohexylene diamine, phenylene diamine, tolylene diamine, 3,3-dichlorobenzidene, 4,4'-methylene-bis-(2-chloroaniline), 3,3-dichloro-4,4-diamino diphenylmethane, sulfonated primary and/or secondary amines, and mixtures thereof. Suitable inorganic amines include hydrazine, substituted hydrazines, and hydrazine reaction products, and mixtures thereof. Suitable ureas include urea and its derivatives, and mixtures thereof. Ethylene diamine is preferably used. The amount of chain extender, which can be added before or after dispersion, typically ranges from about 0.5 to about 1.1 equivalents based on available equivalents of isocyanate.

    [0040] The PA dispersion of the present invention may comprise a homopolymer of acrylates, a copolymer of acrylates, a copolymer of acrylates with other vinyl monomers, and/or mixtures thereof. With the consideration of properties and prices of the products, all traditional comonomers may be used to prepare the polymers and copolymers.

    [0041] Examples of suitable acrylate monomer(s) include esters of (meth)acrylic acid containing 1 to 18 carbon atoms in the alcohol radical, such as methyl methacrylate, butyl methacrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate and stearyl acrylate; di(meth)acrylic acid esters of diols, e.g. ethylene glycol, 1,4-butanediol or 1,6-hexanediol. The monomers including methyl (meth)acrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and glycidyl methacrylate, are preferable.

    [0042] The ethylenically unsaturated nonionic monomers include, for example, (meth)acrylic ester monomers, where (meth)acrylic ester designates methacrylic ester or acrylic ester, including methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, lauryl acrylate, methyl methacrylate, butyl methacrylate, isodecyl methacrylate, lauryl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate; (meth)acrylonitrile; (meth)acrylamide; amino-functional and ureido-functional monomers; monomers bearing acetoacetate-functional groups; styrene and substituted styrenes; butadiene; ethylene, propylene, α-olefins such as 1-decene; vinyl acetate, vinyl butyrate, vinyl versatate and other vinyl esters; and vinyl monomers such as vinyl chloride, vinylidene chloride.

    [0043] Herein, "nonionic monomer" means that the copolymerized monomer residue does not bear an ionic charge between pH=1-14.

    [0044] For the polymerization of monomers, initiators may be used. Examples of suitable initiators include, but are not limited to, peroxides such as potassium peroxy-disulphate, ammonium peroxydisulphate, organic peroxides, organic hydroperoxides and hydrogen peroxide. Redox systems are preferably used, such as water-soluble, radical-producing non-ionogenic peroxides, e.g. t-butyl hydroperoxide, as the oxidation component, and reduction components such as formaldehyde sulphoxylate or ascorbic acid. Ammonium peroxydisulphate, also called ammonium persulfate, is preferably used.

    [0045] The polymerization can be carried out using any technical method for preparing an aqueous emulsion polymerization, employing non-ionic and/or anionic surfactants. Commercial emulsion products may also be used as needed. The designs for the formulations and the reaction technology can be utilized to obtain specific particle morphologies and reactive functionalities so that the PA can match the PU prepolymer/dispersion and/or PUA dispersion to give good film properties. Preferably, the polymerization is carried out with the previously mentioned monomers and is initiated with radical initiators. In one embodiment of the present invention, the mixture of monomers pre-emulsion and the initiator solution are respectively fed into a reactor over a defined period of time, such as 0.8 to 6 hours, preferably 3.5 hours. The initiator solution may comprise an initiator and water. The pre-emulsion comprises monomer mixture, surfactant/emulsifier and water. The polymerization time span is dependent on the reaction conditions, such as temperature, initiator type and dosage, monomer dosage (solid content) and the reactivity of the monomers.

    [0046] Emulsion polymerization is generally conducted at temperatures of about 55°C to about 90°C, preferably 60°C to 85°C, and more preferably 75°C to 80°C. After the completion of the polymerization reaction, the polymer emulsion is allowed to cool down to ambient temperature.

    [0047] The obtained aqueous polymer emulsion has an average particle diameter of 30 to 300 nm, preferably 40 to 90 nm, more preferably 50 to 80 nm.

    [0048] The PUA dispersion made according to the present invention can be used for preparing coating compositions.

    [0049] Additional ingredients of the coating composition include, but are not limited to, stabilizers, colorants, pigments, dispersants, surfactants, paraffins, waxes, UV light stabilizers, rheology modifiers, mildewcides, biocides, fungicides, and other conventional additives. Colorants and pigment dispersions, when used, are typically added in amounts up to about 15% by volume of the total composition.

    [0050] In the present specification, the technical features in each preferred technical solution and more preferred technical solution can be combined with each other to form new technical solutions unless indicated otherwise. For briefness, the applicant omits descriptions of these combinations. However, all the technical solutions obtained by combining these technical features should be deemed as being literally described in the present specification in an explicit manner.

    Examples


    I. Raw Materials:



    [0051] 
    Materials used for preparing the PUA hybrid dispersion
    FunctionChemical natureAbbreviation
    Polyol Polypropylane glycol (Mw=1000) PPG1k
    Polypropylane glycol (Mw=2000) PPG2k
    Poly(butanediol adipate) (Mw=2000) PBA2k
    Polycarprolactone (Mw=2000) PCL2k
    Polyethylene glycol (Mw=400) PEG400
    Polytetrahydrofuran (Mw=2000) PTMEG2k
    Isocyanate Isophorone diisocyanate IPDI
    bis(isocyanatomethyl)cyclohexane ADI
    Catalyst for PU prepolymer Dibutyltin dilaurate DBTDL
    Dispersing improving agent Dimethyolpropionic acid DMPA
    Chain extender 1,4-butanediol BDO
    1,2-propanediamine PDA
    Neutralizing agent Triethylamine TEA
    Ammonia NH3·H2O
    Surfactant Sodium dodecylsulphate SDS
    Monomer Methyl methacrylate MMA
      Butyl acrylate BA
      Acrylic acid AA
      Hydroxyl ethyl methacrylate HEMA
      2-ethylhexyl acrylate 2-EHA
      Styrene St
    Other functional monomer Diacetone acrylamide DAAm
    Acetoacetoxyethyl methacrylate AAEM
    Crosslinker Adipic acid dihydrazide ADH
    Initiator Ammonium persulfate APS
    pH buffer Sodium bicarbonate NaHCO3

    II. Synthesis processes


    Synthesis of PUA1



    [0052] 

    (1) Putting 70g PPG1k, 30g PPG2k 10g PEG400, 0.12g DBTDL catalyst into a three-necked flask, stirring and heating the flask to 115 °C under N2 purging and 10g DMPA was then added to the flask until the system became homogenous and clear;

    (2) Adding 50g IPDI into the flask when the temperature of the reactant reaches to 75°C;

    (3) Keeping the reaction for 120 min at 75°C;

    (4) Adding HEMA into the flask and continuing the reaction for 0.5 h at 75°C; cooling the temperature to 65 °C;

    (5) Adding 100g MMA and 20g BA into the flask, stirring for 5 min to obtain a clear solution;

    (6) Dissolving 1g DAAm and ammonia in water and putting the solution into the flask that contains PU prepolymer, and stirring for about 30 minutes at 80°C;

    (7) Adding 20g BA into the flask;

    (8) Adding 0.4g ammonium persulfate (APS) into the flask separately, and stirring the reactant for 1 h at 80°C;

    (8) Filtering the dispersion with 100-mesh filter cloth and taking the product as PUA1 dispersion.


    Synthesis of PUA2



    [0053] Under otherwise identical reaction conditions to PUA1, the procedure involve: 100 g PPGlk, 100 g ADI, 30 g MMA and 10 g BA.

    Synthesis of PUA3



    [0054] 
    1. (1) Putting 182.5g PPG2k, 156 g PBA2k, 0.5g DBTDL catalyst into a three-necked flask, stirring and heating the flask to 120 °C under N2 purging and adding 24.5g DMPA into the flask until the system became homogenous and clear;
    2. (2) Adding 119g IPDI into the flask when the temperature of the reactant reaches 80 °C;
    3. (3) Keeping the reaction for 150 min at 80°C;
    4. (4) Lowering the temperature to 55 °C and adding 36 mL MMA into the flask, continue to stir for 0.5 h;
    5. (5) Adding 16g TEA at 55°C and stirring for 10 min;
    6. (6) Pouring the above prepolymers into 1200 mL de-ionized water under vigorous stirring;
    7. (7) Adding 12 g propane diamine into the dispersion as chain extender;
    8. (8) Taking 200 mL the dispersion into a 500 mL flask. Adding DI water, sodium hydrogen carbonate, MMA monomers as well as ammonium persulfate into the flask separately, and stirring the reactant for 2 hat 75°C;
    9. (9) Filtrating the dispersion with 100-mesh filter cloth and taking the product as PUA3 dispersion.

    Synthesis of PUA4



    [0055] Making PUA4 under otherwise identical conditions as PUA3, except the initial temperature for dissolving DMPA was 130°C and the reaction temperature was 95°C. The final temperature of prepolymer prior to dispersing was 40°C. The polyols include 169 g PPG2K and 169 g PBA2K.

    Synthesis of PUA5



    [0056] Making PUA5 under otherwise identical conditions as PUA3, except the initial temperature for dissolving DMPA was 130°C and the reaction temperature was 95 °C. The final temperature of prepolymer prior to dispersing was 40°C. The polyols include 154 g PPG2K and 184 g PBA2K.

    Synthesis of PUA6



    [0057] The synthesis procedure was similar to that for PUA4 except for the polyol type and reaction temperatures. The detailed conditions were: Using 338g PCL2K as polyol. The initial temperature for dissolving DMPA was set at 125°C. The reaction temperature was 90°C. Before dispersing, the temperature was cooled to 60 °C.

    Synthesis of PUA7



    [0058] Making PUA7 under otherwise identical conditions as PUA6, except the monomer diluent was 40 g styrene and adding 0.4g DAAm during emulsion polymerization,

    Synthesis of PUA8



    [0059] Making PUA8 under otherwise identical conditions as PUA6, except the monomer diluent was 40 g MMA and adding 0.4g DAAm during emulsion polymerization,

    Synthesis of PUA9



    [0060] Making PUA9 under otherwise identical condition to PUA3 except that the initial temperature for dissolving DMPA was 85°C instead of 120°C for PUA3 and MMA was added together with polyol at the beginning of the reaction.

    Synthesis of PA1



    [0061] 
    1. (1) Charging the four necked flask with 24 g de-ionized water, 0.05 gAPS and 0.26 g SDS surfactant; purging the reactor with N2 for 20 min and then heating to 70°C to initiate the reaction;
    2. (2) Feeding pre-emulsion containing 71 g of de-ionized water, 0.25 g of NaHCO3, 2.5 g of SDS surfactant, 0.4 g of APS initiator and monomer mixture containing 74 g BA, 25 g MMA and 1 g AA.
    3. (3) Adding pre-emulsion over 120-150 min while maintaining the 70°C reaction temperature. Adding 2.5 g DAAm when the remaining pre-emulsion reached the volume of 25 mL;
    4. (4) Cooling to 45°C and adding 2.3 g ammonia over 15-20 min.

    Synthesis of PA2



    [0062] Dow commercial product E3808, copolymer of MMA, and BA, with Tg of -25 °C.

    Synthesis of PA3



    [0063] Dow commercial product E2468, copolymer of MMA, and BA, with Tg of -15 °C.

    Synthesis of PA4



    [0064] Dow commercial product E3188, copolymer of MMA, and BA, with Tg of +50 °C.

    Synthesis of PA5



    [0065] Dow commercial product BZ05-157, copolymer of MMA/ST/BA/EHA/MAA, with Tg of +50 °C.

    Synthesis of PA6



    [0066] Dow commercial product HS01-24, same composition to BZ05-157 except one percent of DAAm was copolymerized, with Tg of +50 °C.

    Synthesis of PA7



    [0067] Dow commercial product SF-230, copolymer of MMA/BA/MAA and one percent of AAEM, with Tg of +5 °C.

    III. Examples



    [0068] The blend samples were prepared by blending PUA and PA emulsions following the recipe in Table 1. Blending is under stirring only with solids of PUA and PA being 40 % and 50 %, respectively. The volumn of each emulsion is 15 mL. ADH crosslinker was added as solid.

    [0069] Cold-blended PUD and PA, as Comparative Example 1, was also listed in the Table, it was prepared by blending, simply under stirring, a commercial PUD product, Bayer PR-240 of solid of 40 wt%, with PA2 in 1:1 volume ratio.
    Table 1
    ExamplesPUAPAADH/g
    1 PUA1    
    2 PUA2    
    3 PUA3    
    4 PUA4    
    5 PUA5    
    6 PUA6    
    7 PUA7    
    8 PUA8    
    Comp. 1 PUD PA2  
    Comp. 2 PUA9    
    Comp.3 PA1    
    Comp.4 PA2    
    Comp.5 PA3    
    Comp.6 PA4    
    Comp.7 PA5    
    Comp.8 PA6    
    Comp.9 PA7    
    1b PUA1 PA1 0
    2b PUA1 PA1 0.02
    3b PUA1 PA1 0.04
    4b PUA1 PA1 0.06
    5b PUA2 PA2 0
    6b PUA3 PA3 0
    7b PUA3 PA4 0
    8b PUA7 PA7 0
    9b PUA8 PA5 0
    10b PUA8 PA5 0.05
    11b PUA8 PA6 0

    IV. Performance test


    1. Temperature effects


    Comparative Example 2 VS Example 3



    [0070] DMPA particulate was seen collected on the wall of the flask and the solution of prepolymer at the end of synthesis is turbid or milky in Comparative Example 2. In contrast, in PUA3 the solution was clear and no particulate DMPA was seen in the flask.

    2. Latex film preparation



    [0071] The films were prepared by casting certain amount of dispersion into a petri dish and let dry for two weeks at room temperature. Generally, after one week of drying, the film was peeled off the petri dish to dry the other side for one week.

    3. Mechanical properties



    [0072] The mechanical properties i.e., the tensile strength and elongation of the latex films were measured using a Gotech-AI 7000M Universal Testing Machine with a crosshead speed of 200 mm/min. The experiments were conducted at room temperature. Rectangle specimens of 80 mm x 10 mm (length x width) free standing film with around 1mm thickness were used. An average value of at least three replicates of each sample was taken.

    [0073] 4. The mechanical properties of films in Example 1 through 8, i.e. PUA1 through PUA8 were summarized in Table 2. Comparative examples 3 to 9 were listed in Table 3.
    Table 2
    ExamplesTensile strength (MPa)Elongation (%)
    1 3.2 520
    2 9.4 303
    3 44 680
    4 22 1024
    5 27 912
    6 22 1050
    7 32 700
    8 25 700
    Table 3
    ExamplesTensile strength (MPa)Elongation (%)
    Comp. 1 - -
    Comp. 2 - -
    Comp.3 0.9 2000
    Comp.4 0.6 1800
    Comp.5 1.5 1100
    Comp.6 - -
    Comp.7 - -
    Comp.8 - -
    Comp.9 1.55 663


    [0074] By comparing Table 2 and Table 3, PUA films of Example 1 to Example 8 showed significantly higher tensile strength than PA films of Comp. 1 to Comp. 9. The tensile strength for PUA ranged from 3.2 MPa to 44 MPs. For the contrast, the strongest PA film had only 1.55 MPa tensile strength. The clear film formed from PUA samples showed high tensile strength and high elongation. Such performance well exceeded the performance of typical EWC emulsion (about 1.0 MPa in tensile strength). For PA in Comparative Examples 6,7 and 8, the PA films cannot form film by themselves at room temperature without using organic solvent as film forming agent. The use of film forming agent can give rise to environmental concerns.
    Table 4
    ExamplesTensile strength (MPa)Elongation (%)
    1b 1.5 1500
    2b 3 500
    3b 4.3 560
    4b 6 332
    5b 6.96 390
    6b 7.7 700
    7b -* -*
    8b 10.6 421
    9b 12.6 233
    10b 15.4 315
    11b 17.1 313
    *Not avalible


    [0075] Those PA samples which could not form film at ambient temperature could instead form continuous film by blending with PUA emulsions. The mechanical performance of the blend samples were summerized in Table 4.

    [0076] As shown in Table 4, Examples 1b through 4b, one can adjust the PUA mechanical properties of the latex films prepared from Example 1 with ADH cross-linking agent to reach a satisfactory mechanical performance. Moreover, the properties can be tailored in a broad range by simply adding various amount of ADH cross-linking agent. Example 9b and 10b also demonstrated the effect of crosslinking. With ADH, both tensile strength and elongation performance were enhanced. The original PA examples Comp. 6 to Comp. 9 cannot form film due to its high Tg. After blending with PUA, they can form film with superior tensile strength, as demonstrated in Examples 7b through 11b. The original PA2 dispersion has very high elongation value but low mechanical strength. After blending, the mechanical properties of the blend film of Example 5b showed better balance in both tensile strength and elongation than each individual component of Example 2 and Comp. 4.

    [0077] Surprisingly, it was found that the clear film of Inventive Example 6b from Example 6 showed both high tensile strength and high elongation. The high modulus can be retained in their blend sample, being as high as 7.7 MPa. The elongation was as high as 700%. Such performance well exceeded the performance of typical EWC emulsion (about 1.0 MPa in tensile strength). In such blend sample, no cross-linking agent was used and the PU component accounts for only about 25 wt% of the total weight, indicating the low cost and high efficiency in improving the mechanical strength.

    5. Storage stability of Example 1b to 1 1b



    [0078] Stability of five PUA/PA blend samples (Example 1b to 5b) and PUD/PA dispersions (cold blend, Comp. 1) was evaluated through heat-ageing at 50°C for 10 days. In all cases, no aggregation was observed from PUA/PA dispersions after 10 days of ageing. As contrast, the PUD/PA dispersion (Comp. 1. did show some gelation and increase in viscosity. The higher stability of the PUA/PA system than PUD/PA system is thought to be derived from the better compatibility between PU phase and PA phase in the PUA/PA system.

    6. Film formation and clarity properties of Example 1b



    [0079] PUA1/PA1 inventive hybrid dispersion (Exp. 1b) produced a film with superior clarity of 5 (5 is the best score and 1 is the worst score), while the clarity of PUD/PA blend (Comp. 1) was 2..

    7. Film formation of Example 7b to 11b, with high-Tg PA



    [0080] Comp. 6 to Comp. 9 alone could not form continuous film at room temperature because of its high Tg. Example 7b to example 1 1b (the blend of high Tg PA and PUA) with the volume of 1:1 could form continuous films and the films are of good clarity, which showed that PUA are well compatible with high Tg PA in the present invention.

    8. Coating performance of Example 7b



    [0081] The blend of PUA3/PA4 (Example 7b) was used as clear coat in wood coating. The performance was summarized in Table 5. It was found that the clear film showed good water resistance and 50% alcohol resistance. No plasticizer was used in the formulation, so the formulation was zero in VOC.
    TABLE 5 Performance of the clear film formed with PUA3/PA4 (Exp. 7b) in 1/1 blend ratio*
    PU (wt%)MFFTaPendulum hardnessPencil hardnessbWater resistancec50% alcohol resistancec100% alcohol resistancec
    4 h26 h2 days(50°C) + 1day(RT)
    25% < 0°C 75 94 107 B 5 5 2
    *No plasticizer;
    a Minimum Film Formation Temperature
    b Hardest to Softest: 4H, 3H, 2H, H, F, HB, B, 2B, 3B, 4B, 5B, 6B;
    c Best=5; Worst=1.



    Claims

    1. A process for making polyurethane/acrylic hybrid dispersions comprising the following continuous steps:

    i) adding at least one polyol into a reactor;

    ii) adding dimethylolpropionic acid (DMPA) simultaneously with/after step i), but before step iii), as water dispersibility enhancing agent at a temperature of from 115 °C to 140 °C to obtain a homogeneous solution;

    iii) adding at least one polyisocyanate at a temperature of from 75°C to 95 °C until the NCO content reaches a constant value to prepare the polyurethane prepolymer;

    iv) adding at least one acrylate monomer, at least one styrenic monomer, or the mixture thereof, as diluent to the polyurethane prepolymer, at a temperature of from 40 °C to 65°C;

    v) adding a neutralizing agent;

    vi) dispersing and extending the polyurethane prepolymer in the presence of the acrylate monomer, and/or the styrenic monomer of step iv); and

    vii) adding at least one ethylenically unsaturated nonionic monomer, and co-polymerizing it together with the acrylate monomer, and/or the styrenic monomer of step iv), to get the polyurethane/acrylic hybrid dispersion.


     
    2. The process according to claim 1 wherein the acrylate monomer is selected from the group consisting of (meth)acrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycidyl methacrylate, and mixtures thereof.
     
    3. The process according to claim 1 wherein the at least one polyisocyanate is a diisocyanate.
     
    4. The process according to claim 3 wherein the diisocyanate is selected from, hexamethylene-1,6-diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, 2,4,4-trimethyl-hexamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and mixtures thereof.
     
    5. The process according to claim 1 wherein the at least one polyol is selected from polyether diols, polyester diols and multi-functional polyols.
     
    6. The process according to claim 1 wherein the at least one polyol comprises a mixture of a polyether polyol and a polyester polyol.
     
    7. The process according to claim 1 wherein organic solvents are not used.
     
    8. A process for making polyurethane/acrylic hybrid dispersions comprising cold-blending the polyurethane/acrylic hybrid dispersions made according to claim 1 with a polyacrylate dispersion under agitation.
     
    9. The process according to claim 8 comprising modifying both polyurethane/acrylic hybrid dispersion and polyacrylate dispersion by copolymerization with diacetone acrylamide or acetoacetoxyethyl methacrylate; and adding adipic acid dihydrazide as crosslinker, into the blend.
     
    10. A polyurethane/acrylic hybrid dispersion prepared according to the process of claim 1 wherein the polyurethane prepolymer does not contain particulate DMPA.
     
    11. A coating composition comprising the polyurethane/acrylic hybrid dispersion according to claim 10.
     
    12. A polyurethane/acrylic hybrid dispersion prepared according to the process of claim 1, wherein the at least one polyol comprises polyether polyols, polyester polyols, polycarbonate polyols, polyhydroxy polyester amides, hydroxyl-containing polycaprolactones, hydroxyl-containing acrylic polymers, hydroxyl-containing epoxides, polyhydroxy polycarbonates, polyhydroxy polyacetals, polyhydroxy polythioethers, polysiloxane polyols, ethoxylated polysiloxane polyols, polybutadiene polyols and hydrogenated polybutadiene polyols, polyisobutylene polyols, polyacrylate polyols, polyols derived from halogenated polyesters and polyethers, or mixtures thereof.
     
    13. A polyurethane/acrylic hybrid dispersion prepared according to the process of claim 1, wherein the at least one polyol comprises polyether polyols, polyester polyols, polycarbonate polyols or mixtures thereof.
     
    14. A polyurethane/acrylic hybrid dispersion prepared according to the process of claim 1, wherein the polyurethane/acrylic hybrid dispersion is modified by copolymerization with diacetone acrylamide or acetoacetoxyethyl methacrylate; and adipic acid dihydrazide, as crosslinker, is added into the polyurethane/acrylic hybrid dispersion/polyacrylate dispersion blend.
     


    Ansprüche

    1. Ein Verfahren zum Herstellen von hybriden Polyurethan-/Acryldispersionen, beinhaltend die folgenden kontinuierlichen Schritte:

    i) Zugeben mindestens eines Polyols in einen Reaktor;

    ii) Zugeben von Dimethylolpropionsäure (DMPA) simultan mit/nach Schritt i), aber vor Schritt iii), als Mittel zur Verbesserung der Wasserdispergierbarkeit bei einer Temperatur von 115 °C bis 140 °C, um eine homogene Lösung zu erhalten;

    iii) Zugeben mindestens eines Polyisocyanats bei einer Temperatur von 75°C bis 95 °C, bis der NCO-Gehalt einen konstanten Wert erreicht, um das Polyurethanpräpolymer zuzubereiten;

    iv) Zugeben mindestens eines Acrylatmonomers, mindestens eines Styrolmonomers oder der Mischung davon als Verdünnungsmittel zu dem Polyurethanpräpolymer bei einer Temperatur von 40°C bis 65 °C;

    v) Zugeben eines Neutralisationsmittels;

    vi) Dispergieren und Strecken des Polyurethanpräpolymers in Gegenwart des Acrylatmonomers und/oder des Styrolmonomers von Schritt iv); und

    vii) Zugeben mindestens eines ethylenisch ungesättigten nichtionischen Monomers und Copolymerisieren desselben zusammen mit dem Acrylatmonomer und/oder dem Styrolmonomer von Schritt iv), um die hybride Polyurethan-/Acryldispersionen zu erlangen.


     
    2. Verfahren gemäß Anspruch 1, wobei das Acrylatmonomer aus der Gruppe ausgewählt ist, die aus Folgendem besteht: (Meth)acrylat, Ethylacrylat, Butylacrylat, Hexylacrylat, 2-Ethylhexylacrylat, Hydroxyethyl(meth)acrylat, Hydroxypropyl(meth)acrylat, Glycidylmethacrylat und Mischungen davon.
     
    3. Verfahren gemäß Anspruch 1, wobei das mindestens eine Polyisocyanat ein Diisocyanat ist.
     
    4. Verfahren gemäß Anspruch 3, wobei das Diisocyanat aus Folgendem ausgewählt ist: Hexamethylen-1,6-diisocyanat, 2,2,4-Trimethylhexamethylendiisocyanat, 2,4,4-Trimethylhexamethylendiisocyanat, 1,3-Bis(isocyanatomethyl)cyclohexan, Dicyclohexylmethandiisocyanat, Isophorondiisocyanat und Mischungen davon.
     
    5. Verfahren gemäß Anspruch 1, wobei das mindestens eine Polyol aus Polyetherdiolen, Polyesterdiolen und multifunktionellen Polyolen ausgewählt ist.
     
    6. Verfahren gemäß Anspruch 1, wobei das mindestens eine Polyol eine Mischung von einem Polyetherpolyol und einem Polyesterpolyol beinhaltet.
     
    7. Verfahren gemäß Anspruch 1, wobei keine organischen Lösungsmittel verwendet werden.
     
    8. Ein Verfahren zum Herstellen von hybriden Polyurethan-/Acryldispersionen, beinhaltend das Kaltvermischen der gemäß Anspruch 1 hergestellten hybriden Polyurethan-/Acryldispersionen mit einer Polyacrylatdispersion unter Rühren.
     
    9. Verfahren gemäß Anspruch 8, beinhaltend das Modifizieren von sowohl der hybriden Polyurethan-/Acryldispersion und der Polyacrylatdispersion durch Copolymerisation mit Diacetonacrylamid oder Acetoacetoxyethylmethacrylat; und das Zugeben von Adipinsäuredihydrazid als Vernetzer in das Gemisch.
     
    10. Eine hybride Polyurethan-/Acryldispersion, die nach dem Verfahren gemäß Anspruch 1 zubereitet ist, wobei das Polyurethanpräpolymer keine partikelförmige DMPA enthält.
     
    11. Eine Beschichtungszusammensetzung, beinhaltend die hybride Polyurethan-/Acryldispersion gemäß Anspruch 10.
     
    12. Eine hybride Polyurethan-/Acryldispersion, die nach dem Verfahren gemäß Anspruch 1 zubereitet ist, wobei das mindestens eine Polyol Folgendes beinhaltet:
    Polyetherpolyole, Polyesterpolyole, Polycarbonatpolyole, Polyhydroxypolyesteramide, hydroxylhaltige Polycaprolactone, hydroxylhaltige Acrylpolymere, hydroxylhaltige Epoxide, Polyhydroxypolycarbonate, Polyhydroxypolyacetale, Polyhydroxypolythioether, Polysiloxanpolyole, ethoxylierte Polysiloxanpolyole, Polybutadienpolyole und hydrierte Polybutadienpolyole, Polyisobutylenpolyole, Polyacrylatpolyole, von halogeniertenen Poleystern und Polyethern abgeleitete Polyole oder Mischungen davon.
     
    13. Eine hybride Polyurethan-/Acryldispersion, die nach dem Verfahren gemäß Anspruch 1 zubereitet ist, wobei das mindestens eine Polyol Folgendes beinhaltet:
    Polyetherpolyole, Polyesterpolyole, Polycarbonatpolyole oder Mischungen davon.
     
    14. Eine hybride Polyurethan-/Acryldispersion, die nach dem Verfahren gemäß Anspruch 1 zubereitet ist, wobei die hybride Polyurethan-/Acryldispersion durch Copolymerisation mit Diacetonacrylamid oder Acetoacetoxyethylmethacrylat modifiziert ist; und wobei Adipinsäuredihydrazid dem Gemisch von hybrider Polyurethan-/Acryldispersion/Polyacrylatdispersion als Vernetzer zugegeben wird.
     


    Revendications

    1. Un procédé pour la réalisation de dispersions hybrides de polyuréthane/acrylique comprenant les étapes continues suivantes :

    i) ajout d'au moins un polyol dans un réacteur ;

    ii) ajout d'acide diméthylolpropionique (DMPA) simultanément avec/après l'étape i), mais avant l'étape iii), en tant qu'agent améliorant la dispersibilité dans l'eau à une température allant de 115 °C à 140 °C afin d'obtenir une solution homogène ;

    iii) ajout d'au moins un polyisocyanate à une température allant de 75 °C à 95 °C jusqu'à ce que la teneur en NCO atteigne une valeur constante afin de préparer le prépolymère polyuréthane ;

    iv) ajout d'au moins un monomère acrylate, d'au moins un monomère styrénique, ou du mélange de ceux-ci, en tant que diluant au prépolymère polyuréthane, à une température allant de 40 °C à 65 °C ;

    v) ajout d'un agent neutralisant ;

    vi) dispersion et extension du prépolymère polyuréthane en présence du monomère acrylate, et/ou du monomère styrénique de l'étape iv) ; et

    vii) ajout d'au moins un monomère non ionique éthyléniquement insaturé, et copolymérisation de celui-ci en conjonction avec le monomère acrylate, et/ou le monomère styrénique de l'étape iv), afin de parvenir à la dispersion hybride de polyuréthane/acrylique.


     
    2. Le procédé selon la revendication 1 dans lequel le monomère acrylate est sélectionné dans le groupe constitué du (méth)acrylate, de l'acrylate d'éthyle, de l'acrylate de butyle, de l'acrylate d'hexyle, de l'acrylate de 2-éthylhexyle, du (méth)acrylate d'hydroxyéthyle, du (méth)acrylate d'hydroxypropyle, du méthacrylate de glycidyle, et de mélanges de ceux-ci.
     
    3. Le procédé selon la revendication 1 dans lequel l'au moins un polyisocyanate est un diisocyanate.
     
    4. Le procédé selon la revendication 3 dans lequel le diisocyanate est sélectionné parmi l'hexaméthylène-1,6-diisocyanate, le 2,2,4-triméthyl-hexaméthylène diisocyanate, le 2,4,4-triméthyl-hexaméthylène diisocyanate, le 1,3-bis(isocyanatométhyl)cyclohexane, le dicyclohexylméthane diisocyanate, l'isophorone diisocyanate, et des mélanges de ceux-ci.
     
    5. Le procédé selon la revendication 1 dans lequel l'au moins un polyol est sélectionné parmi des polyéther diols, des polyester diols et des polyols multifonctionnels.
     
    6. Le procédé selon la revendication 1 dans lequel l'au moins un polyol comprend un mélange d'un polyéther polyol et d'un polyester polyol.
     
    7. Le procédé selon la revendication 1 dans lequel des solvants organiques ne sont pas utilisés.
     
    8. Un procédé pour la réalisation de dispersions hybrides de polyuréthane/acrylique comprenant le mélange homogène à froid des dispersions hybrides de polyuréthane/acrylique réalisées selon la revendication 1 avec une dispersion de polyacrylate sous agitation.
     
    9. Le procédé selon la revendication 8 comprenant la modification à la fois de la dispersion hybride de polyuréthane/acrylique et de la dispersion de polyacrylate par copolymérisation avec du diacétone acrylamide ou du méthacrylate d'acétoacétoxyéthyle ; et l'ajout de dihydrazide d'acide adipique en tant qu'agent de réticulation, dans le mélange homogène.
     
    10. Une dispersion hybride de polyuréthane/acrylique préparée selon le procédé de la revendication 1 dans laquelle le prépolymère polyuréthane ne contient pas de DMPA particulaire.
     
    11. Une composition de revêtement comprenant la dispersion hybride de polyuréthane/acrylique selon la revendication 10.
     
    12. Une dispersion hybride de polyuréthane/acrylique préparée selon le procédé de la revendication 1, dans laquelle l'au moins un polyol comprend des polyéther polyols, des polyester polyols, des polycarbonate polyols, des polyhydroxypolyester amides, des polycaprolactones contenant de l'hydroxyle, des polymères acryliques contenant de l'hydroxyle, des époxydes contenant de l'hydroxyle, des polyhydroxypolycarbonates, des polyhydroxypolyacétals, des polyhydroxypolythioéthers, des polysiloxane polyols, des polysiloxane polyols éthoxylés, des polybutadiène polyols et des polybutadiène polyols hydrogénés, des polyisobutylène polyols, des polyacrylate polyols, des polyols dérivés de polyéthers et de polyesters halogénés, ou des mélanges de ceux-ci.
     
    13. Une dispersion hybride de polyuréthane/acrylique préparée selon le procédé de la revendication 1, dans laquelle l'au moins un polyol comprend des polyéther polyols, des polyester polyols, des polycarbonate polyols ou des mélanges de ceux-ci.
     
    14. Une dispersion hybride de polyuréthane/acrylique préparée selon le procédé de la revendication 1, la dispersion hybride de polyuréthane/acrylique étant modifiée par copolymérisation avec du diacétone acrylamide ou du méthacrylate d'acétoacétoxyéthyle ; et du dihydrazide d'acide adipique, en tant qu'agent de réticulation, étant ajouté dans le mélange homogène dispersion hybride de polyuréthane/acrylique/dispersion de polyacrylate.
     






    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description