(19)
(11)EP 3 357 942 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
17.06.2020 Bulletin 2020/25

(21)Application number: 17853325.3

(22)Date of filing:  05.09.2017
(51)International Patent Classification (IPC): 
C08F 14/06(2006.01)
C08F 2/44(2006.01)
C08L 27/06(2006.01)
C08F 2/02(2006.01)
C08K 5/524(2006.01)
(86)International application number:
PCT/KR2017/009713
(87)International publication number:
WO 2018/056611 (29.03.2018 Gazette  2018/13)

(54)

METHOD FOR PREPARING VINYL CHLORIDE-BASED POLYMER, VINYL CHLORIDE-BASED POLYMER, AND VINYL CHLORIDE-BASED POLYMER COMPOSITION

VERFAHREN ZUR HERSTELLUNG EINES POLYMERS AUF VINYLCHLORIDBASIS, POLYMER AUF VINYLCHLORIDBASIS UND POLYMERZUSAMMENSETZUNG AUF VINYLCHLORIDBASIS

PROCÉDÉ DE PRÉPARATION DE POLYMÈRE À BASE DE CHLORURE DE VINYLE, POLYMÈRE À BASE DE CHLORURE DE VINYLE ET COMPOSITION DE POLYMÈRE À BASE DE CHLORURE DE VINYLE


(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: 26.09.2016 KR 20160123388
01.09.2017 KR 20170112014

(43)Date of publication of application:
08.08.2018 Bulletin 2018/32

(73)Proprietor: LG Chem, Ltd.
Seoul 07336 (KR)

(72)Inventors:
  • AHN, Seong Yong
    Daejeon 34122 (KR)
  • KIM, Kun Ji
    Daejeon 34122 (KR)
  • LEE, Se Woong
    Daejeon 34122 (KR)
  • HA, Hyun Kyou
    Daejeon 34122 (KR)
  • SHIN, Seong Jae
    Daejeon 34122 (KR)

(74)Representative: Goddar, Heinz J. 
Boehmert & Boehmert Anwaltspartnerschaft mbB Pettenkoferstrasse 22
80336 München
80336 München (DE)


(56)References cited: : 
EP-A1- 3 061 788
GB-A- 1 577 030
JP-A- S5 278 985
KR-A- 20100 023 340
GB-A- 1 463 737
JP-A- S5 153 589
JP-A- H06 199 911
KR-A- 20160 061 126
  
      
    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

    [Technical Field]


    Technical Field



    [0001] The present invention relates to a method of preparing a vinyl chloride-based polymer and particularly, to a method of preparing a vinyl chloride-based polymer exhibiting improved thermal stability and transparency by adding a phosphite in a polymerization process.

    [Background Art]



    [0002] A vinyl chloride-based polymer is a synthetic resin which is used the most among thermoplastic resins. In a polymerization method of a vinyl chloride-based polymer, there are suspension polymerization, emulsion polymerization, and bulk polymerization. Among these, the bulk polymerization is a method in which only a vinyl chloride-based monomer, an initiator, and, as necessary, a reaction additive are supplied and polymerized without use of water and a dispersant (emulsifying agent). The bulk polymerization has advantages in that a device is simple, a reaction is rapid, a yield is high because a purification process comprising distillation, extraction, and the like is not undergone, a polymer with high purity can be obtained, and the polymer can be handled without change.

    [0003] However, the bulk polymerization has a disadvantage in that it is difficult to adjust a temperature due to generation of a large amount of heat in the polymerization. Also, the bulk polymerization has a disadvantage in that it is difficult to diffuse heat of reaction by conduction or convection because there is no material which is capable of absorbing and removing heat of polymerization other than a vinyl chloride-based monomer and viscosity of a polymerization material increases as the polymerization is progressed. Accordingly, a vinyl chloride-based polymer prepared by the bulk polymerization may be thermally damaged due to heat of reaction generated in a bulk polymerization process or unexpectedly generated heat. Therefore, it is very important to ensure thermal stability of a vinyl chloride-based polymer.

    [0004] EP 3 061 788 A1, GB 1 577 030 A and GB 1 463 737 A disclose the manufacturing of PVC by bulk polymerization in the presence of additives. Phosphites are recommended in these prior art documents, so that the methods of the art lead to PVC having phosphites dispersed in the polymer matrix.

    [Disclosure]


    [Technical Problem]



    [0005] It is an aspect of the present invention to provide a method of preparing a vinyl chloride-based polymer, which uses a phosphite serving as both a thermal stabilizer and an antioxidant.

    [Technical Solution]



    [0006] In order to accomplish the above objective, there is provided a method of preparing a vinyl chloride-based polymer comprising: bulk-polymerizing a vinyl chloride-based monomer in the presence of an initiator (Step 1); and preparing a vinyl chloride-based polymer after the bulk polymerization (Step 2), wherein a phosphite is added in the step 1, wherein the step 1 comprises: first bulk-polymerizing a first vinyl chloride-based monomer in the presence of a first initiator to prepare nuclear particles (Step 1-1); and second bulk-polymerizing the nuclear particles, a first vinyl chloride-based monomer unreacted in the step 1-1, and a second vinyl chloride-based monomer in the presence of a second initiator (Step 1-2), wherein the phosphite is added in at least one step of the step 1-1 and step 1-2, wherein the first bulk polymerization is performed at a temperature of 60 to 80 °C under a pressure of 9 to 14 kg/cm2 G, and wherein the second bulk polymerization is performed at a temperature of 50 to 70 °C under a pressure of 7 to 12 kg/cm2 G.

    [0007] Further embodiments are disclosed in the dependent claims.

    [Advantageous Effects]



    [0008] A method of preparing a vinyl chloride-based polymer according to the present invention can minimize thermal damage to a vinyl chloride-based polymer which may occur due to heat unexpectedly generated in a bulk polymerization process in which it is difficult to adjust a temperature by adding a phosphite in a polymerization process. Also, the phosphite can suppress a side reaction of an initiator which may occur in a bulk polymerization process. Accordingly, transparency can be improved by minimizing coloration of a vinyl chloride-based polymer caused by the side reaction, and a bulk polymerization rate can be prevented from being degraded.

    [0009] In addition, a vinyl chloride-based polymer and a vinyl chloride-based polymer composition including the same can exhibit an improvement in both thermal stability and transparency.

    [Mode for Invention]



    [0010] Hereinafter, the present invention will be described in more detail for promoting an understanding of the present invention.

    [0011] Terms and words used in this specification and claims should not be interpreted as limited to commonly used meanings or meanings in dictionaries and should be interpreted with meanings and concepts which are consistent with the technological scope of the invention based on the principle that the inventors have appropriately defined concepts of terms in order to describe the invention in the best way.

    [0012] In the present invention, a vinyl chloride-based polymer may refer to a polymer in which a phosphite is dispersed in a matrix of a vinyl chloride-based polymer. Specifically, the vinyl chloride-based polymer may refer to a polymer in which, although the vinyl chloride-based polymer and the phosphite are not chemically combined, the phosphite is uniformly dispersed and fixed in a matrix of the vinyl chloride-based polymer, that is, in a three-dimensional network structure, and thus two materials are integrated.

    [0013] A method of preparing a vinyl chloride-based polymer according to the present invention comprises bulk-polymerizing a vinyl chloride-based monomer in the presence of an initiator (Step 1), and a phosphite is added in the step 1.

    [0014] Specifically, the step 1 comprises first bulk-polymerizing a first vinyl chloride-based monomer in the presence of a first initiator to prepare nuclear particles (Step 1-1); and second bulk-polymerizing the nuclear particles, a first vinyl chloride-based monomer unreacted in the step 1-1, and a second vinyl chloride-based monomer in the presence of a second initiator (Step 1-2).

    [0015] The first and second initiators may be the same or different from each other, and each independently, at least one selected from the group consisting of a diacyl peroxide such as dicumyl peroxide, dipentyl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, or the like; a peroxycarbonate such as diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, or the like; a peroxyester such as t-butyl peroxy neodecanoate, t-butyl peroxy neoheptanoate, t-amyl peroxy neodecanoate, cumyl peroxy neodecanoate, cumyl peroxy neoheptanoate, 1,1,3,3-tetramethylbutyl peroxy neodecanoate, or the like; an azo compound such as azobis-2,4-dimethylvaleronitrile or the like; and a sulfate such as potassium persulfate, ammonium persulfate, or the like.

    [0016] The first and second vinyl chloride-based monomers may be the same or different from each other, and each independently, a pure vinyl chloride-based monomer or a mixed monomer comprising the pure vinyl chloride-based monomer as a main component and a vinyl-based monomer copolymerizable with the pure vinyl chloride-based monomer. The mixed monomer may comprise the vinyl-based monomer in an amount of 1 to 50 parts by weight with respect to 100 parts by weight of the vinyl chloride-based monomer. The vinyl-based monomer may be at least one selected from the group consisting of an olefin compound such as ethylene, propylene, or the like; a vinyl ester such as vinyl acetate, vinyl propionate, or the like; an unsaturated nitrile such as acrylonitrile or the like; a vinyl alkyl ether such as vinyl methyl ether, vinyl ethyl ether, or the like; an unsaturated fatty acid such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, or the like; and an anhydride of these fatty acids.

    [0017] The first initiator may be included in an amount of 0.01 to 0.2 parts by weight, particularly 0.03 to 0.15 parts by weight, and more particularly 0.05 to 0.1 parts by weight with respect to 100 parts by weight of the first vinyl chloride-based monomer. When the first initiator is included within the above range, stability of a process in the polymerization is improved.

    [0018] The second initiator may be included in an amount of 0.03 to 0.6 parts by weight, particularly 0.05 to 0.4 parts by weight, and more particularly 0.08 to 0.3 parts by weight with respect to 100 parts by weight of the nuclear particles, the first vinyl chloride-based monomer unreacted in the step 1-1, and the second vinyl chloride-based monomer. When the second initiator is included within the above range, stability of a process in the polymerization is improved.

    [0019] The first bulk polymerization is performed at a temperature of 60 to 80 °C under a pressure of 9 to 14 kg/cm2 G. When the above-described conditions are satisfied, the nuclear particles may be formed from the first vinyl chloride-based monomer. When a polymerization conversion rate is 10% to 15%, the first bulk polymerization may be terminated.

    [0020] The second bulk polymerization is performed at a temperature of 50 to 70 °C under a pressure of 7 to 12 kg/cm2 G. When the above-described conditions are satisfied, the nuclear particles may be grown to form a vinyl chloride-based polymer.

    [0021] Meanwhile, the phosphite is added in at least one of the step 1-1 and step 1-2. Specifically, in the step 1-1, the phosphite may be added before or during the first bulk polymerization. In the step 1-2, the phosphite may be added before, during, or after the second bulk polymerization. More particularly, the phosphite may be added before the first bulk polymerization in the step 1-1, and may be added before the second bulk polymerization in the step 1-2. The phosphite may be added while stirring is maintained or prior to stirring.

    [0022] When the phosphite is added in the above-described step, thermal damage to a vinyl chloride-based polymer which may occur due to heat unexpectedly generated in a bulk polymerization process in which it is difficult to adjust a temperature may be prevented. Also, the phosphite may suppress a side reaction caused by an initiator which may occur in the first and second bulk polymerization processes. Accordingly, coloration caused by the side reaction may be minimized, and thus transparency of a vinyl chloride-based polymer which is a final product may be improved. Also, a bulk polymerization rate may not be degraded and may be constantly maintained. In addition, since a product using a vinyl chloride-based polymer is processed at high temperature, it is very important to ensure transparency and thermal stability. When the phosphite is added in a polymerization process of the vinyl chloride-based polymer, the phosphite may reach a matrix of the vinyl chloride-based polymer and thus may be dispersed. Accordingly, a product prepared using a composition comprising the vinyl chloride-based polymer comprising the phosphite according to the preparation method of the present invention may have transparency and thermal stability superior to a product prepared using a composition including the vinyl chloride-based polymer and the phosphite.

    [0023] The phosphite may be a compound represented by Chemical Formula 1 below.

    In Chemical Formula 1,

    L1 to L3 are the same or different from each other, and each independently, are a C1 to C20 alkylene group or a C6 to C20 arylene group, or refer to a direct bonding between O and R1 to R3, respectively, and

    R1 to R3 are the same or different from each other, and each independently, a substituted or unsubstituted and linear or branched C1 to C20 alkyl group or a substituted or unsubstituted C6 to C20 aryl group.



    [0024] Here, "direct bonding" means that O and R1 to R3 are directly connected without L1 to L3.

    [0025] A phosphite represented by Chemical Formula 1 may be one selected from the group consisting of compounds listed in Table 1 below.
    [Table 1]
     Chemical NameStructural Formula
    1 Triethyl phosphite

    2 Triisopropyl phosphite

    3 Triisodecyl phosphite

    4 Tridodecyl phosphite

    5 Phenyl diisodecyl phosphite

    6 Diphenyl isodecyl phosphite

    7 Triphenyl phosphite

    8 Phenyl bis(4-nonylphenyl) phosphite

    9 Tris(4-octylphenyl) phosphite

    10 Tris[(4-1-phenylethyl)phenyl] phosphite



    [0026] The phosphite may be added in an amount of 0.001 to 1 part by weight, particularly 0.003 to 0.1 parts by weight with respect to 100 parts by weight of the first and second vinyl chloride-based monomers. When the phosphite is added within the above range, thermal damage to a vinyl chloride-based polymer which may occur due to heat unexpectedly generated in a bulk polymerization process may be minimized. Since a side reaction caused by the first and second initiators which may occur in the first and second bulk polymerization processes may be suppressed, coloration caused by the side reaction may be minimized, thereby transparency of a vinyl chloride-based polymer which is a final product may be improved. Also, since the side reaction caused by the initiators is suppressed, a bulk polymerization rate may not be degraded and may be constantly maintained.

    [0027] The phosphite may be added in a state of a solution mixed with a solvent. Also, the phosphite may be included in an amount of 0.1 to 5 wt%, particularly 0.5 to 2 wt% with respect to the total weight of the solution. When the phosphite is added in the above-described state and range, the phosphite may be further uniformly dispersed in the first and second vinyl chloride-based monomers, and thus thermal stability and transparency of a vinyl chloride-based polymer which is a final product may be further improved. The phosphite may be added in one or more selected from the group consisting of the first vinyl chloride-based monomer and the second vinyl chloride-based monomer through a spraying method using a spray or a nozzle. Also, after being added, the phosphite may be dispersed in at least one selected from the group consisting of the first vinyl chloride-based monomer and the second vinyl chloride-based monomer through stirring.

    [0028] The solvent may be an alcohol solvent which is easily volatilized in a bulk polymerization process, and thus does not affect polymerization. The alcohol solvent may be at least one selected from the group consisting of methanol, ethanol, isopropanol, 1-methoxy propanol, butanol, ethyl hexyl alcohol, and terpineol.

    [0029] The method of preparing a vinyl chloride-based polymer according to the present invention comprises obtaining a vinyl chloride-based polymer after the bulk polymerization (Step 2).

    [0030] In the step 2, when a bulk polymerization conversion rate reaches 50 to 70%, the bulk polymerization may be completed, and a reaction-terminating agent may be added to complete the bulk polymerization.

    [0031] The reaction-terminating agent is a material which serves to terminate a reaction by causing the loss of function of the second initiator, and may be one or more selected from the group consisting of a phenol compound, an amine compound, a nitrile compound, and a sulfur compound. The phenol compound may be at least one selected from the group consisting of triethylene glycol-bis-3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate, hydroquinone, p-methoxyphenol, t-butyl-4-hydroxyanisole, n-octadecyl-3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, 2,5-di-t-butylhydroquinone, 4,4'-butylidene-bis(3-methyl-6-t-butyl phenol), t-butylcatechol, 4,4-thiobis(6-t-butyl-m-cresol), and tocopherol. The amine compound may be one or more selected from the group consisting of N,N-diphenyl-p-phenylenediamine and 4,4-bis(dimethylbenzyl)diphenyl. The nitrile compound may be 4-hydroxy-2,2,6,6-tetramethyl-piperidine-1-oxyl. The sulfur compound may be at least one selected from the group consisting of dodecyl mercaptan and 1,2-biphenyl-2-thiol.

    [0032] When the reaction-terminating agent is added, an additive such as an antioxidant and the like may be added as necessary. The antioxidant may be added for the purpose of making the color of a vinyl chloride-based polymer white.

    [0033] A vinyl chloride-based polymer may be prepared by the method of preparing a vinyl chloride-based polymer according to an embodiment of the present invention, and may include a vinyl chloride-based polymer and a phosphite, wherein the phosphite may be dispersed in a matrix of the vinyl chloride-based polymer. Specifically, the phosphite may be uniformly dispersed and fixed in a matrix of the vinyl chloride-based polymer, that is, a three-dimensional network structure, and thus two materials are integrated.

    [0034] The phosphite may be included in an amount of 0.001 to 2 wt%, particularly 0.008 to 1 wt%, and more particularly 0.005 to 0.1 wt% with respect to the total weight of the vinyl chloride-based polymer. The phosphite is hardly lost in the preparation process of the vinyl chloride-based polymer, and particularly, 90% or more of a phosphite added in the preparation process of the vinyl chloride-based polymer may be included in the polymer. Accordingly, the phosphite may be included within the above range with respect to the total weight of the vinyl chloride-based polymer. When the phosphite is included within the above range, the phosphite is not lost in the preparation process of the vinyl chloride-based polymer, and performance of the vinyl chloride-based polymer is not degraded, thereby a vinyl chloride-based polymer excellent in both thermal stability and transparency may be provided.

    [0035] A vinyl chloride-based polymer composition of the present invention may include the vinyl chloride-based polymer and at least one selected from the group consisting of a stabilizer, a processing aid, an impact modifier, and a lubricant.

    [0036] The stabilizer is a material which increases stability with respect to heat to prevent coloration and decomposition, and may be a metallic stabilizer or an organic acid metal salt stabilizer. The metallic stabilizer may be at least one selected from the group consisting of a lead-based stabilizer, a (organic) tin-based stabilizer, a cadmium-based stabilizer, and a barium-based stabilizer. The organic acid metal salt may be a carboxylic acid, organic phosphoric acid, or phenol metal salt. The carboxylic acid may be at least one selected from the group consisting of caproic acid, caprylic acid, pelargonic acid, 2-ethylhexyl acid, capric acid, neodecanoic acid, undecylenic acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, 12-hydroxystearic acid, chlorostearic acid, 12-ketostearic acid, phenyl stearic acid, ricinoleic acid, linoleic acid, linolenic acid, oleic acid, arachic acid, behenic acid, erucic acid, brassidic acid, pseudo acids, resin fatty acids, coconut oil fatty acids, tung oil fatty acids, soybean oil fatty acids, cotton seed oil fatty acids, benzoic acid, p-t-butylbenzoic acid, ethylbenzoic acid, isopropylbenzoic acid, toluic acid, xylic acid, salicylic acid, 5-t-octylsalicylic acid, naphthenic acid, and cyclohexanecarboxylic acid. The organic phosphoric acid may be at least one selected from the group consisting of monooctyl phosphate, dioctyl phosphate, monododecyl phosphate, didodecyl phosphate, monooctadecyl phosphate, dioctadecyl phosphate, mono(nonylphenyl) phosphate, di(nonylphenyl) phosphate, phosphonic acid nonylphenyl ester, and phosphonic acid stearyl ester. The phenol may be at least one selected from the group consisting of phenol, cresol, ethylphenol, cyclohexylphenol, nonylphenol, and dodecylphenol. The metal salt may be a neutral salt, an acidic salt, a basic salt, or an overbased complex.

    [0037] The processing aid is a material which promotes gelation of a vinyl chloride-based polymer, and may be a homopolymer or a copolymer of alkyl methacrylate such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, or the like; a copolymer of the alkyl methacrylate and an alkyl acrylate such as methyl acrylate, ethyl acrylate, butyl acrylate, or the like; a copolymer of the alkyl methacrylate and an aromatic vinyl compound such as styrene, α-methyl styrene, vinyltoluene, or the like; or a copolymer of the alkyl methacrylate and a vinyl cyanide compound such as acrylonitrile, methacrylonitrile, or the like. The processing aid may be used in combination of one or two or more thereof.

    [0038] The impact modifier is a material which imparts elasticity to a vinyl chloride-based polymer to reinforce impact resistance, and may be at least one selected from the group consisting of a methyl methacrylate-butadiene styrene (MBS)-based polymer, a chlorinated polyethylene-based copolymer, an ethylene vinyl acetate-based polymer, an acrylic polymer, and a butadiene-based polymer.

    [0039] The lubricant is a material which improves processability and interfacial properties of a vinyl chloride-based polymer, and may be a hydrocarbon-based lubricant such as low-molecular-weight wax, paraffin wax, polyethylene wax, a chlorinated hydrocarbon, fluorocarbon, or the like; a natural wax-based lubricant such as carnauba wax, candelilla wax, or the like; a fatty acid-based lubricant such as a higher fatty acid (e.g., lauric acid, stearic acid, behenic acid, or the like), an oxygenated fatty acid (e.g, hydroxystearic acid), or the like; an aliphatic amide-based lubricant such as an aliphatic amide compound (e.g, stearylamide, laurylamide, oleylamide, or the like), an alkylene bis aliphatic amide compound (e.g., methylene bis stearylamide and ethylene bis stearylamide) or the like; a alcohol ester-based lubricant of fatty acids such as a monohydric alcohol ester compound of fatty acids (e.g., stearyl stearate, butyl stearate, distearyl phthalate, or the like), a polyhydric alcohol ester compound of fatty acid (e.g., glycerin tristearate, sorbitan tristearate, pentaerythritol tetrastearate, dipentaerythritol hexastearate, polyglycerin polyricinoleate, hydrogenated castor oil, or the like), a composite ester compound of a monobasic fatty acid such as adipic acid stearic acid ester of dipentaerythritol, a polybasic organic acid, and a polyhydric alcohol, or the like; an aliphatic alcohol-based lubricant such as stearyl alcohol, lauryl alcohol, palmityl alcohol, or the like; metal soap; a montanic acid-based lubricant such as partially saponified montanic acid ester or the like; an acrylic lubricant; or a silicone oil. The lubricant may be used alone or in combination of two or more.

    [Best Mode]



    [0040] Hereinafter, preferred embodiments of the present invention will be described in order to aid in understanding the present invention. However, it is apparent to those skilled in the art that the description proposed herein is just a preferable example for the purpose of illustration only, and is not intended to limit or define the scope of the invention.

    <Preparation of vinyl chloride-based polymer>


    Examples 1-1 and 1-2 and Comparative Examples 1-1 and 1-2



    [0041] A polymerization device comprising a 0.2 m3 preliminary polymerization reactor, a 0.5 m3 polymerization reactor, a reflux condenser which is connected to the polymerization reactor and controls a polymerization temperature, and a pipe for recovering vinyl chloride which is connected to the reflux condenser and releases an unreacted vinyl chloride-based monomer was used to polymerize a vinyl chloride-based monomer as follows.

    [0042] 140 kg of a vinyl chloride monomer and 85 g of t-butyl peroxy neodecanoate as an initiator were sequentially added to the preliminary polymerization reactor which is degassed so as to be in a high vacuum, and stirred. While the stirring was maintained, a pressure of the preliminary polymerization reactor increased to 12 kg/cm2 G, and first bulk polymerization was performed at 75 °C to prepare nuclear particles. In this case, a conversion rate of the first bulk polymerization was 10%.

    [0043] Subsequently, to the polymerization reactor, all of the nuclear particles, all of a vinyl chloride monomer unreacted in the first bulk polymerization, 80 kg of an additional vinyl chloride monomer, and 200 g of 1,1,3,3-tetramethylbutyl peroxy neodecanoate as an initiator were sequentially added and stirred. While the stirring was maintained, polymerization was initiated under conditions of a temperature and a pressure listed in Table 2 below, and second bulk polymerization was performed for a time listed in Table 2 below. When a polymerization conversion rate listed in Table 2 below was reached, a phosphite solution listed in Table 3 below and 200 g of butylated hydroxytoluene as an antioxidant were sequentially added, and then a residual unreacted monomer was recovered in a vacuum while stirring was maintained to obtain a vinyl chloride-based polymer.
    [Table 2]
    ClassificationPolymerization temperature (°C)Polymerization pressure (kg/cm2 G)Polymerization conversion rate (%)Polymerization time (min)
    Example 1-1 52 7.5 55 180
    Example 1-2 60 9.0 60 200
    Comparative Example 1-1 52 7.5 55 180
    Comparative Example 1-2 90 9.0 60 200
    [Table 3]
    ClassificationPhosphiteSolventTotal weight (kg)
    TypeContent (wt%)TypeContent (wt%)
    Example 1-1 Triphenyl phosphite 1 Ethanol 99 1
    Example 1-2 Tridodecyl phosphite 1 Ethanol 99 10
    Comparative Example 1-1 - - - - -
    Comparative Example 1-2 - - - - -

    Examples 1-3 and 1-4



    [0044] A polymerization device comprising a 0.2 m3 preliminary polymerization reactor, a 0.5 m3 polymerization reactor, a reflux condenser which is connected to the polymerization reactor and controls a polymerization temperature, and a pipe for recovering vinyl chloride which is connected to the reflux condenser and releases an unreacted vinyl chloride-based monomer was used to polymerize a vinyl chloride-based monomer as follows.

    [0045] 140 kg of a vinyl chloride monomer, 85 g of t-butyl peroxy neodecanoate as an initiator, and a solution listed in Table 4 below were sequentially added to the preliminary polymerization reactor which is degassed so as to be in a high vacuum, and stirred. While the stirring was maintained, a pressure of the preliminary polymerization reactor increased to 12 kg/cm2 G, and first bulk polymerization was performed at 75 °C to prepare nuclear particles. In this case, a conversion rate of the first bulk polymerization was 10%.

    [0046] Subsequently, to the polymerization reactor, all of the nuclear particles, all of a vinyl chloride monomer unreacted in the first bulk polymerization, 80 kg of an additional vinyl chloride monomer, and 200 g of 1,1,3,3-tetramethylbutyl peroxy neodecanoate as an initiator were sequentially added and stirred. While the stirring was maintained, second bulk polymerization was performed at a temperature of 52 °C under a pressure of 7.5 kg/cm2 G for a time listed in Table 4 below. In this case, a polymerization conversion rate was 55%. 200 g of butylated hydroxytoluene as an antioxidant was added, and then a residual unreacted monomer was recovered in a vacuum while stirring was maintained to obtain a vinyl chloride-based polymer.
    [Table 4]
    ClassificationPolymerization time (min)PhosphiteSolventTotal weight (kg)
    TypeContent (wt%)TypeContent (wt%)
    Example 1-3 180 Phenyl-bis(4-nonylphenyl) phosphite 1 Ethanol 99 1
    Example 1-4 200 Tris(4-octylphenyl) phosphite 1 Ethanol 99 3

    Comparative Example 1-3



    [0047] A polymerization device including a 1 m3 polymerization reactor, a reflux condenser which is connected to the polymerization reactor and controls a polymerization temperature, and a pipe for recovering vinyl chloride which is connected to the reflux condenser and releases an unreacted vinyl chloride-based monomer was used to polymerize a vinyl chloride-based monomer as follows.

    [0048] First, 390 kg of deionized water was added in the polymerization reactor, and 150 g of polyvinyl alcohol (degree of hydration: 78.5%), 100 g of polyvinyl alcohol (degree of hydration: 40.7%), and 30 g of hydroxypropyl methylcellulose all together were added as a dispersant. Subsequently, 300 kg of a vinyl chloride-based monomer was added, and 30 g of di-(2-ethylhexyl)peroxydicarbonate and 120 g of t-butylperoxy neodecarbonate were added as an initiator. Polymerization was performed while an inner temperature of the polymerization reactor was maintained at 57 °C. When a polymerization rate reached 60%, 30 kg of a solution comprising 1 wt% triphenyl phosphate (solvent: ethanol) was injected using a pump. When an inner pressure of the polymerization reactor reached 6.3 kg/cm2, 15 g of 4-hydroxy-2,2,6,6-tetramethyl-piperidine-1-oxyl as a reaction-terminating agent, 60 g of triethylene glycol-bis-3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate as an antioxidant were sequentially added. Afterward, an unreacted monomer was recovered, and the polymerization was terminated, thereby obtaining a first polymer slurry. Subsequently, the first polymer slurry was recovered, and stripping and dehydrating processes were performed to separate an unreacted vinyl chloride-based monomer and water, thereby obtaining a second polymer slurry. The second polymer slurry was hot-air dried in a fluid bed dryer at 60 °C to separate residual water. Afterward, a vinyl chloride-based polymer in the form of powder was obtained through a screening facility. A content of a phosphite in the vinyl chloride-based polymer thus obtained was measured, but measurement was not possible because the phosphite was already hydrolyzed.

    <Preparation of sheet>


    Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-4



    [0049] 100 parts by weight of a vinyl chloride-based polymer listed in Table 5 below, 2 parts by weight of a mono/dimethyl tin mercaptide composite as a tin-based stabilizer, 1 part by weight of an acryl and methyl methacrylate (MMA) composite as a processing aid, 5 parts by weight of a methyl methacrylate (MMA) and butadiene composite as an impact modifier, 0.5 parts by weight of composite of a fatty acid ester and wax as a lubricant, and an additive listed in Table 5 below were blended and mixed using a rolling mill at 185 °C for 3 minutes, thereby obtaining a preliminary sheet having a thickness of 0.5 mm. The preliminary sheet was cut, and then ten cut sheets were stacked one on top of the other and compressed all at once, thereby preparing a sheet having a thickness of 6 mm.
    [Table 5]
    ClassificationVinyl chloride-based polymerAdditive
    TypeContent (parts by weight)
    Example 2-1 Example 1-1 - -
    Example 2-2 Example 1-2 - -
    Example 2-3 Example 1-3 - -
    Example 2-4 Example 1-4 - -
    Comparative Example 2-1 Comparative Example 1-1 - -
    Comparative Example 2-2 Comparative Example 1-2 - -
    Comparative Example 2-3 Comparative Example 1-1 Triphenyl phosphite 1
    Comparative Example 2-4 Comparative Example 1-3 - -

    Examples 3-1 to 34 and Comparative Examples 3-1 to 3-4



    [0050] 100 parts by weight of a vinyl chloride-based polymer listed in Table 6 below, 4 parts by weight of a mono/dimethyl tin mercaptide composite as a tin-based stabilizer, 1 part by weight of an acryl and methyl methacrylate (MMA) composite as a processing aid, 6 parts by weight of a methyl methacrylate (MMA) and butadiene composite as an impact modifier, 0.5 part by weight of composite of a fatty acid ester and wax as a lubricant, and an additive listed in Table 6 below were blended and mixed using a rolling mill at 185 °C for 3 minutes, thereby obtaining a preliminary sheet having a thickness of 0.5 mm. The preliminary sheet was cut, and ten cut sheets were stacked one on top of the other, put into a frame having a thickness of 3 mm, and compressed all at once. Then, the compressed sheets were preheated at 185 °C for 2 minutes, heated at 185 °C for 3 minutes under a pressure of 10 kg/cm2, and cooled at 185 °C for 2 minutes under a pressure of 15 kg/cm2, thereby preparing a sheet having a thickness of 3 mm.
    [Table 6]
    ClassificationVinyl chloride-based polymerAdditive
    TypeContent (parts by weight)
    Example 3-1 Example 1-1 - -
    Example 3-2 Example 1-2 - -
    Example 3-3 Example 1-3 - -
    Example 3-4 Example 1-4 - -
    Comparative Example 3-1 Comparative Example 1-1 - -
    Comparative Example 3-2 Comparative Example 1-2 - -
    Comparative Example 3-3 Comparative Example 1-1 Triphenyl phosphite 1
    Comparative Example 3-4 Comparative Example 1-3 - -

    Experimental Example 1


    <Measurement of haze rate and transmission rate>



    [0051] The haze rate and transmission rate of each of the sheets according to Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-4 were measured using Haze-gard plus commercially available from BYK-Gardner GmbH, results of which are shown in Table 7 below.

    [0052] Haze rate: defined as percentage of light that passes through a sample with respect to initially radiated beam (as a larger amount of light passes through a sample, the haze rate is lower, which means better transparency)

    [0053] Transmission rate: inversely proportional to haze rate
    [Table 7]
    ClassificationHaze rate (%)Transmission rate (%)
    Example 2-1 6.6 86.5
    Example 2-2 7.0 85.5
    Example 2-3 6.8 85.9
    Example 2-4 7.1 85.0
    Comparative Example 2-1 10.5 77.6
    Comparative Example 2-2 10.7 77.1
    Comparative Example 2-3 8.5 83.0
    Comparative Example 2-4 10.6 76.4


    [0054] Referring to Table 7, it can be seen that the sheets according to Examples 2-1 to 2-4 had a haze rate of 6.6% to 7.1% and a transmission rate of 85.0% to 86.5%, indicating excellent transparency.

    [0055] However, it can be seen that the sheets according to Comparative Examples 2-1 and 2-2 had a haze rate of 10.5% and 10.7% and a transmission rate of 77.6% and 77.1%, indicating transparency lower than that of the sheets according to Examples 2-1 to 2-4. Also, it can be seen that the sheet according to Comparative Example 2-3 had a higher haze rate and a lower transmission rate compared to those of the sheets according to Examples 2-1 to 2-4, and exhibited a decrease in transparency because, although a content of a phosphite in the sheet was similar to that of a sheet prepared using the vinyl chloride-based polymer according to the present invention, a phosphite was not dispersed in a matrix of a vinyl chloride-based polymer. In addition, it can be seen that the sheet according to Comparative Example 2-4 exhibited an increase in haze rate and a decrease in transmission rate, like a sheet prepared using a vinyl chloride-based polymer not comprising a phosphite.

    Experimental Example 2


    <Evaluation and measurement of thermal stability>



    [0056] In order to evaluate thermal stability of each of the sheets according to Examples 3-1 to 3-4 and Comparative Examples 3-1 to 3-4, a whiteness index (W.I) was measured using NR-3000 commercially available from Nippon Denshoku Industries Co., Ltd., results of which are shown in Table 8 below. Generally, thermal stability can be evaluated from a whiteness index, and a higher whiteness index indicates excellent thermal stability.
    [Table 8]
    ClassificationWhiteness index
    Example 3-1 32.90
    Example 3-2 32.45
    Example 3-3 32.10
    Example 3-4 31.80
    Comparative Example 3-1 23.50
    Comparative Example 3-2 23.00
    Comparative Example 3-3 28.30
    Comparative Example 3-4 28.00


    [0057] Referring to Table 8, it can be seen that the sheets according to Examples 3-1 to 3-4 had a whiteness index of 31.80 to 32.90, indicating excellent thermal stability. On the other hand, it can be seen that the sheets according to Comparative Examples 3-1 and 3-2 had a whiteness index of 23.5 and 23, indicating thermal stability lower than that of the sheets according to Examples 3-1 to 3-4. Also, it can be seen that the sheet according to Comparative Example 3-3 had a whiteness index lower than that of the sheets according to Examples 3-1 to 3-4.

    [0058] It can be seen that the sheet according to Comparative Example 3-3 exhibited a decrease in thermal stability because, although a content of a phosphite in the sheet was similar to that of a sheet prepared using the vinyl chloride-based polymer according to the present invention, a phosphite was not dispersed in a matrix of a vinyl chloride-based polymer. Also, it can be seen that the sheet according to Comparative Example 3-4 exhibited a decrease in whiteness index, like a sheet prepared using a vinyl chloride-based polymer not comprising a phosphite. Although the sheet according to Comparative Example 3-4 exhibited an excellent whiteness index compared to that of the sheets according to Comparative Examples 3-1 and 3-2, it is just due to a difference in a polymerization method and is not significant.


    Claims

    1. A method of preparing a vinyl chloride-based polymer comprising:

    bulk-polymerizing a vinyl chloride-based monomer in the presence of an initiator (Step 1); and

    preparing a vinyl chloride-based polymer after the bulk polymerization (Step 2),

    wherein a phosphite is added in the step 1,

    wherein the step 1 comprises:

    first bulk-polymerizing a first vinyl chloride-based monomer in the presence of a first initiator to prepare nuclear particles (Step 1-1); and

    second bulk-polymerizing the nuclear particles, a first vinyl chloride-based monomer unreacted in the step 1-1, and a second vinyl chloride-based monomer in the presence of a second initiator (Step 1-2),

    wherein the phosphite is added in at least one step of the step 1-1 and step 1-2 wherein the first bulk polymerization is performed at a temperature of 60 to 80 °C under a pressure of 9 to 14 kg/cm2 G, and wherein the second bulk polymerization is performed at a temperature of 50 to 70 °C under a pressure of 7 to 12 kg/cm2 G.


     
    2. The method of claim 1, wherein the phosphite is a compound represented by Formula 1 below:

    wherein L1 to L3 are the same or different from each other, and each independently a C1 to C20 alkylene group or a C6 to C20 arylene group, or refer to a direct bonding between O and

    R1 to R3, respectively, and

    R1 to R3 are the same or different from each other, and each independently, a substituted or unsubstituted and linear or branched C1 to C20 alkyl group or a substituted or unsubstituted C6 to C20 aryl group.


     
    3. The method of claim 2, wherein the phosphite is one or two or more selected from the group consisting of triethyl phosphite, triisopropyl phosphite, triisodecyl phosphite, tridodecyl phosphite, phenyl diisodecyl phosphite, diphenyl isodecyl phosphite, triphenyl phosphite, phenyl bis(4-nonylphenyl) phosphite, tris(4-octylphenyl) phosphite, and tris((4-1-phenylethyl)phenyl) phosphite.
     
    4. The method of claim 1, wherein the phosphite is added in an amount of 0.001 to 1 part by weight with respect to 100 parts by weight of the vinyl chloride-based monomer.
     
    5. The method of claim 1, wherein the phosphite is added in a state of a solution mixed with a solvent.
     
    6. The method of claim 1, wherein the phosphite is dispersed in a matrix of the vinyl chloride-based polymer.
     
    7. The method of claim 6, wherein the phosphite is dispersed and fixed in a three-dimensional network structure of the vinyl chloride-based polymer.
     


    Ansprüche

    1. Verfahren zum Herstellen eines Polymers auf Vinylchloridbasis, umfassend:

    Massepolymerisieren eines Monomers auf Vinylchloridbasis in der Gegenwart eines Initiators (Schritt 1); und

    Herstellen eines Polymers auf Vinylchloridbasis nach der Massepolymerisation (Schritt 2),

    wobei ein Phosphit im Schritt 1 zugegeben wird,

    wobei der Schritt 1 umfasst:

    erstes Massepolymerisieren eines ersten Monomers auf Vinylchloridbasis in der Gegenwart eines ersten Initiators, um Keimteilchen herzustellen (Schritt 1-1); und

    zweites Massepolymerisieren der Keimteilchen, eines ersten, im Schritt 1-1 nicht umgesetzten Monomers auf Vinylchloridbasis und eines zweiten Monomers auf Vinylchloridbasis in der Gegenwart eines zweiten Initiators (Schritt 1-2),

    wobei das Phosphit in wenigstens einem Schritt des Schritts 1-1 und des Schritts 1-2 zugegeben wird,

    wobei die erste Massepolymerisation bei einer Temperatur von 60 bis 80°C unter einem Druck von 9 bis 14 kg/cm2 G durchgeführt wird, und wobei die zweite Massepolymerisation bei einer Temperatur von 50 bis 70°C unter einem Druck von 7 bis 12 kg/cm2 G durchgeführt wird.


     
    2. Verfahren nach Anspruch 1, wobei das Phosphit eine durch Formel 1 unten dargestellte Verbindung ist:

    wobei L1 bis L3 gleich oder verschieden voneinander sind und jeweils unabhängig eine C1- bis C20-Alkylengruppe oder eine C6- bis C20-Arylengruppe sind oder sich auf eine direkte Bindung zwischen O und R1 bis R3 beziehen, und

    R1 bis R3 gleich oder verschieden voneinander sind und jeweils unabhängig eine substituierte oder unsubstituierte und lineare oder verzweigte C1- bis C20-Alkylgruppe oder eine substituierte oder unsubstituierte C6- bis 20-Arylgruppe sind.


     
    3. Verfahren nach Anspruch 2, wobei das Phosphit eines oder zwei oder mehrere ist, ausgewählt aus der Gruppe bestehend aus Triethylphosphit, Triisopropylphosphit, Triisodecylphosphit, Tridodecylphosphit, Phenyldiisodecylphosphit, Diphenylisodecylphosphit, Triphenylphosphit, Phenylbis(4-nonylphenyl)phosphit, Tris(4-octylphenyl)phosphit und Tris((4-1-phenylethyl)phenyl)phosphit.
     
    4. Verfahren nach Anspruch 1, wobei das Phosphit in einer Menge von 0,001 bis 1 Gewichtsteil in Bezug auf 100 Gewichtsteile des Monomers auf Vinylchloridbasis zugegeben wird.
     
    5. Verfahren nach Anspruch 1, wobei das Phosphit in einem Zustand einer Lösung, gemischt mit einem Lösungsmittel, zugegeben wird.
     
    6. Verfahren nach Anspruch 1, wobei das Phosphit in einer Matrix des Polymers auf Vinylchloridbasis dispergiert wird.
     
    7. Verfahren nach Anspruch 6, wobei das Phosphit in einer dreidimensionalen Netzwerkstruktur des Polymers auf Vinylchloridbasis dispergiert und fixiert wird.
     


    Revendications

    1. Procédé de préparation d'un polymère à base de chlorure de vinyle consistant à :

    polymériser en masse un monomère à base de chlorure de vinyle en présence d'un initiateur (Étape 1) ; et

    préparer un polymère à base de chlorure de vinyle après la polymérisation en masse (Étape 2),

    dans lequel un phosphite est ajouté à l'étape 1,

    dans lequel l'étape 1 consiste à :

    premièrement polymériser en masse un premier monomère à base de chlorure de vinyle en présence d'un premier initiateur pour préparer des particules nucléaires (Étape 1-1) ; et

    deuxièmement polymériser en masse les particules nucléaires, un premier monomère à base de chlorure de vinyle n'ayant pas réagi à l'étape 1-1 et un deuxième monomère à base de chlorure de vinyle en présence d'un deuxième initiateur (Étape 1-2),

    dans lequel le phosphite est ajouté dans au moins soit l'étape 1-1, soit l'étape 1-2,

    dans lequel la première polymérisation en masse est effectuée à une température comprise entre 60 et 80°C à une pression comprise entre 9 et 14 kg/cm2 G, et dans lequel la deuxième polymérisation en masse est effectuée à une température comprise entre 50 et 70°C à une pression comprise entre 7 et 12 kg/cm2 G.


     
    2. Procédé selon la revendication 1, dans lequel le phosphite est un composé représenté par la Formule 1 ci-dessous :

    dans lequel L1 à L3 sont les mêmes ou différents l'un de l'autre et, chacun indépendamment un groupe alkylène en C1 à C20 ou un groupe arylène en C6 à C20, ou réfère à une liaison directe entre O et R1 à R3, respectivement, et

    R1 à R3 sont les mêmes ou différents l'un de l'autre et, chacun indépendamment, un groupe alkyle en C1 à C20 linéaire ou ramifié non substitué ou substitué ou un groupe aryle en C6 à C20 non substitué ou substitué.


     
    3. Procédé selon la revendication 2, dans lequel le phosphite est un ou deux ou plus de deux éléments sélectionnés dans le groupe constitué de phosphite de triéthyle, phosphite de triisopropyle, phosphite de triisodécyle, phosphite de tridodécyle, phosphite de phényle diisodécyle, phosphite de diphényle isodécyle, phosphite de triphényle, phosphite de phényle bis(4-nonylphényle), phosphite de tris(4-octylphényle) et phosphite de tris((4-1-phényléthyl)phényle).
     
    4. Procédé selon la revendication 1, dans lequel le phosphite est ajouté dans une quantité comprise entre 0,001 et 1 partie en poids pour 100 parties en poids du monomère à base de chlorure de vinyle.
     
    5. Procédé selon la revendication 1, dans lequel le phosphite est ajouté dans un état d'une solution mélangée avec un solvant.
     
    6. Procédé selon la revendication 1, dans lequel le phosphite est dispersé dans une matrice du polymère à base de chlorure de vinyle.
     
    7. Procédé selon la revendication 6, dans lequel le phosphite est dispersé et fixé dans une structure de réseau tridimensionnelle du polymère à base de chlorure de vinyle.
     






    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