Method for producing functionalized partially hydrolyzed polyvinyl acetate

Abstract

The present disclosure relates to a method of producing a relief precursor comprising a functionalized partially hydrolyzed polyvinyl acetate, the present in the melt of partially hydrolyzed polyvinyl acetate as component A with a reactive compound bearing at least one ethylenically unsaturated group and at least one reactive group reactive to hydroxyl or acetate groups as component B in the presence of at least one stabilizer as component C and optionally in the presence of a catalyst as component D The present invention relates to a process for the preparation of a mixture of components A, B, C and optionally D, comprising the steps of: a) optionally drying one or more of the components A, B, C and optionally D, b) optionally premixing two or more of the components A, B, C and optionally D, c) feeding said components into a mixing device capable of heating, melting and mixing the components A, B, C and optionally D, d) heating, melting and mixing the components A, B, C and optionally D in the device to produce a melt and reacting the components A and B in the melt, e) optionally cooling or shaping and cooling the resulting mixture.

Description

[0001] This application is a divisional application of an international application with the international application number PCT / EP2018 / 082993, titled "Process for Producing Functionalized Partially Hydrolyzed Polyvinyl Acetate", filed by Kuraray Europe GmbH, Ensisheim, Germany on November 29, 2018. The international application PCT / EP2018 / 082993 entered the Chinese national phase on June 29, 2020, with the national application number 201880084612.X. Technical Field

[0002] The present invention relates to a process for producing partially hydrolyzed polyvinyl acetate using reactive extrusion, polymers obtained therefrom, and compositions containing these. Background Art

[0003] The production of functionalized polyvinyl acetate is known and described, for example, in USRE 2740, DE 3015419, EP0079514, DE 3322993, EP 849635, and EP 962828. USRE 2740 describes the production of crosslinked hydrogels in water by esterification of polyvinyl alcohol with methacrylic anhydride in the presence of potassium sulfate and sodium thiosulfate. DE 3015419 describes the conversion of partially hydrolyzed polyvinyl acetate suspended in dichloromethane with methacrylic anhydride at 50 °C for 3 hours. Subsequently, the polymer must be separated by filtration and dried. A similar method is known from EP 0 079 514, where the reaction is carried out in acetone and at 60 °C. In this case, the polymer produced must also be separated by filtration and dried. The method is improved in DE3322993 by using tertiary amines (such as pyridine derivatives) in acetone and in toluene. Filtration and drying are also necessary here. The method is modified in EP 962 828, where a mixture of alkyl carbonates (such as ethylene carbonate, propylene carbonate) is used as a solvent.

[0004] A method is described in WO 96 / 18133, where polyvinyl alcohol is reacted with an unsaturated aldehyde or the corresponding acetal in an aqueous solution.

[0005] The disadvantages of these methods are the use of organic solvents and the need to remove them after the reaction is complete. In addition, the starting polymer is not completely dissolved but only swollen, which leads to non-uniform reactions that are more intense at the surface of the swollen particles than in the core. These methods are carried out batchwise, while a continuously operating method is preferred.

[0006] EP 670 521 discloses the conversion of polyvinyl alcohol in the melt at about 210 °C with carboxylic anhydrides, in particular cyclic internal anhydrides, to introduce carboxyl-containing side chains. For this purpose, the resulting polymer has to be purified in an additional precipitation step to remove water and organic solvents. Subsequently, the functionalized polyvinyl alcohol is reacted with glycidyl methacrylate to obtain polyvinyl alcohol having unsaturated double bonds. This method is cumbersome and expensive.

[0007] DE 19925133 describes the modification of partially hydrolyzed polyvinyl acetate by extrusion and using glycidyl acrylate. However, in a previous step, a plasticizer such as ethylene glycol or an alkyl carbonate is compounded into the polymer to soften it. The disadvantage of this method is that only certain plasticizers can be used because other plasticizers adversely affect the reaction. In addition, these plasticizers may have unwanted effects in certain applications. Plasticizers generally cannot be crosslinked and may be extracted, which can lead to an increase in the hardness of the product. Plasticizers may also be the reason that the material is too soft for some applications.

[0008] JPH 07173219 describes the modification of partially hydrolyzed polyvinyl acetate in the melt with carboxylic anhydrides, excluding anhydrides containing double bonds, most likely due to crosslinking during the reaction. SUMMARY OF THE INVENTION

[0009] An object of the present invention is to provide a simple method for introducing ethylenically unsaturated groups into partially hydrolyzed polyvinyl acetate without using solvents or plasticizers, which provides a functionalized partially hydrolyzed polyvinyl acetate without unwanted impurities and having a uniform distribution of ethylenically unsaturated functional groups. The method should preferably operate in a continuous mode and have fewer process steps.

[0010] This object is solved by a method for producing a functionalized partially hydrolyzed polyvinyl acetate comprising vinyl alcohol, vinyl acetate and functionalized vinyl alcohol units, by reacting in the melt a partially hydrolyzed polyvinyl acetate as component A, a reactive compound having at least one ethylenically unsaturated group and at least one reactive group reactive towards a hydroxyl or acetate group as component B, in the presence of at least one stabilizer as component C and optionally in the presence of a catalyst as component D, the method comprising the steps of:

[0011] a) optionally drying one or more of components A, B, C and optionally D,

[0012] b) optionally premixing at least two of components A, B, C and optionally D,

[0013] c) feeding the components into a mixing device capable of heating, melting and mixing components A, B, C and optionally D,

[0014] d) Heating, melting, and mixing components A, B, C, and optionally D in the device to produce a melt and reacting component A in B in the melt,

[0015] e) Optionally cooling or shaping and cooling the resulting mixture.

[0016] The partially hydrolyzed polyvinyl acetate used as component A contains vinyl alcohol units, vinyl acetate units, and functionalized vinyl alcohol units and may optionally contain additional units incorporated during the polymerization of vinyl acetate and / or by post-polymerization reactions. These other units may be present in an amount of from 0.1 to 50 mol%, preferably from 0.1 to 25 mol%, more preferably from 0.1 to 15 mol%, based on all monomer units of the partially hydrolyzed polyvinyl acetate. These other units may be derived from other compounds bearing vinyl units, such as α-olefins, such as ethylene and propylene; (meth)acrylic acid and its salts; (meth)acrylates, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate; (meth)acrylamide; (meth)acrylamide derivatives, such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, diacetone(meth)acrylamide, (meth)acrylamidopropylsulfonic acid and its salts, (meth)acrylamidopropyldimethylamine and its salts or quaternary salts, and N-hydroxymethyl(meth)acrylamide and its derivatives; vinyl ethers, such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether; nitriles, such as acrylonitrile and methacrylonitrile; vinyl halides, such as vinyl chloride and vinyl fluoride; vinylidene halides, such as vinylidene chloride and vinylidene fluoride; allyl compounds, such as allyl acetate, allyl alcohol, allyl, allyl chloride, and 3,4-diacetoxy-1-butene, 3,4-dihydroxy-1-butene, 1,4-diacetoxy-1-butene, and 1,4-dihydroxy-1-butene; unsaturated dicarboxylic acids, such as maleic acid, itaconic acid, and fumaric acid, and their salts or esters; vinylsilyl compounds, such as vinyltrimethoxysilane; isopropyl acetate; etc. Preferred additional units are: vinyl units, such as from α-olefins, such as ethylene; (meth)acrylic acid and its salts; (meth)acrylates. The polymer structure of the vinyl acetate copolymer may be syndiotactic, isotactic, atactic, linear, cyclic, branched, grafted, or dendritic or a combination thereof. It is possible to use statistical copolymers as well as alternating or block copolymers. The polymer may be insoluble, soluble in organic solvents or aqueous solutions or a combination thereof. The polymer is preferably soluble, dispersible, or emulsifiable in water or aqueous solutions.

[0017] The degree of hydrolysis of the starting partially hydrolyzed polyvinyl acetate (i.e., before functionalization) is generally in the range of 0.01 to 99.9 mol%, preferably in the range of 50 to 99 mol%, more preferably in the range of 60 to 95 mol%, and most preferably in the range of 70 to 90 mol%, based on all monomer units (including comonomer units) contained in the partially hydrolyzed polyvinyl acetate. In a further embodiment, the viscosity of the starting partially hydrolyzed polyvinyl acetate (measured as a 4 wt% aqueous solution) is in the range of 0.1 to 50 mPa s, preferably in the range of 1 to 30 Pa s, and more preferably in the range of 2 to 10 mPa s.

[0018] The reactive compound having at least one ethylenically unsaturated group used as component B has at least one reactive group capable of reacting with one or more OH- or OAc-groups of the partially hydrolyzed polyvinyl acetate. A mixture of two or more reactive compounds can also be used. It is also possible to use compounds having more than one reactive group and / or more than one carbon-carbon double bond. The reactive groups of the reactive compounds of component B are selected from isocyanate groups, isothiocyanate groups, epoxy groups, aziridine groups, sulfonyl halide groups, acyl halide groups, carboxylic anhydride groups, carboxylic acid groups, carboxylic ester groups, aldehyde groups, maleimide groups, N-hydroxysuccinimide ester groups or any combination thereof. The reactive groups are preferably carboxylic anhydride groups, carboxylic acid groups, carboxylic ester groups or aldehyde groups. The most preferred reactive groups are carboxylic anhydride groups and carboxylic acid groups. The ethylenically unsaturated group can be a substituted or unsubstituted carbon-carbon double bond, which can form part of an aliphatic or heteroaliphatic ring. The substituents at the double bond can be aliphatic, heteroaliphatic or aromatic. The ethylenically unsaturated double bond is preferably capable of undergoing free radical polymerization and / or cationic polymerization and / or crosslinking reaction and / or further functionalization reaction. The ethylenically unsaturated group is preferably present as a methacrylic type group, an acrylic type group, a vinyl ether group, a styrene group, an allyl ether group, a vinylsilyl group, an acrylamide group, a methacrylamide group, an epoxyacrylate group or any combination thereof. In a preferred embodiment, the reactive compound B is a methacrylic acid or acrylic acid derivative. The reactive compound is preferably (meth)acryloyl halide, (meth)acrylate, (meth)acrylic anhydride or a derivative prepared by using an activator for carboxylic acids (such as dicyclohexylcarbodiimide or 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide) or the corresponding NHS-ester (N-hydroxysuccinimide) of methacrylic acid. The most preferred reactive compounds are (meth)acrylic acid, (meth)acrylic anhydride and (meth)glycidyl acrylate. Particularly preferred reactive compounds are methacrylic anhydride, acrylic anhydride and (meth)glycidyl acrylate. The reactive compound is covalently linked to the polymer via a linking group and has at least one of the following structural units (Ia)-(Id). The reactive compound is covalently linked to the polymer via a linking group. The linking unit has at least one of the following structural units: ester, thioester amide, ether, thioether, urethane, urea, thiourea.

[0019] The amount of the reactive compound in the reaction mixture is in the range of 0.1 to 30% by weight, preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, and most preferably 1 to 13% by weight, based on the total weight of the reaction mixture containing components A, B, C and optionally D.

[0020] The stabilizer used as component C is a free radical scavenging compound, and mixtures of these stabilizers can also be used. Examples of stabilizers are hindered phenols, hindered amines including hindered amines of the N-H, N-R or N-OR type, hydroquinones, phenothiazines, mercaptans and combinations thereof. These compounds are listed, for example, in "Handbuch Kunststoff Additive", edited by Ralph-Dieter Maier, Michael Schiller, 4th edition, Carl Hanser Verlag München 2016. Preferably, hindered phenols or mercaptans or hindered amines are used, such as 2,6-di-tert-butyl-4-methylphenol (BHT), pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), 2-tert-butyl-4-ethylphenol, 5-chloro-2-hydroxybenzophenone, 5-chloro-2-hydroxy-4-methylbenzophenone, 2,4-di-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)phenol, 2,6-di-tert-butyl-4-(dimethylaminomethyl)phenol, 3′,5′-dichloro-2′-hydroxyacetophenone, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2′,4′-dihydroxy-3′-propylacetophenone, 2,2′-ethylidene-bis(4,6-di-tert-butylphenol), 2-hydroxy-4-(octyloxy)benzophenone, 2,2′-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol], 2,2′-methylenebis(6-tert-butyl-4-ethylphenol), 5,5′-methylenebis(2-hydroxy-4-methoxybenzophenone), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, 1,3,5-tris(2-hydroxyethyl)isocyanurate, menthyl anthranilate, octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate); octadecyl 3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate;Ethylene bis(oxyethylene) bis-(3-(5-tert-butyl-4-hydroxy-m-tolyl) propionate), N,N'-hexane-1,6-diyl bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propanamide), benzenepropopanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9 branched alkyl ester, 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole, 2-(2-hydroxy-3,5-diperyl-phenyl)benzotriazole, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, N-(1-acetyl-2,2,6,6-tetramethyl-4-piperidyl)-2-dodecylsuccinimide, derivatives of 2,2,6,6-tetramethylpiperidine, poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidyl)imino]]), bis(2,2,6,6,-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1,2,2,6,6-pentamethyl-4-piperidyl methyl sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)-2-butyl-2-(4-hydroxy-3,5-di-tert-butylbenzyl) malonate, 2,6-di-tert-butyl-4-methylphenol, alkylated bisphenols, such as 2,2-methylenebis-(4-methyl-6-tert-butylphenol);2-(4-Hydroxy-3,5-di-tert-butylanilino)-4,6-bis(n-octylthio)-1,3,5-triazine, dilauryl thiodipropionate, distearyl thiodipropionate, 4-allyloxy-2-hydroxybenzophenone, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-amylphenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate, 2-(2H-benzotriazol-2-yl)-4-methyl-6-(2-propenyl)phenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(4-benzoyl-3-hydroxyphenoxy)ethyl acrylate, 3,9-bis(2,4-di-tert-butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol, 5-ethyl-1-aza-3,7-dioxabicyclo[3.3.0]octane, ethyl 2-cyano-3,3-diphenylacrylate, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate, 2-ethylhexyl salicylate or phenothiazine. Among hydroquinones, for example, monomethyl ether hydroquinone (MEHQ), trimethyl dihydroquinone, polymeric trimethyl dihydroquinone, 2,3-dimethyl hydroquinone, 2-methoxy hydroquinone, methyl-p-benzoquinone, methyl hydroquinone, tetrachloro-1,4-benzoquinone are preferred. Particularly preferred stabilizers are BHT and MEHQ. The amount of stabilizer in the reaction mixture is in the range of 0.01 to 5% by weight, preferably 0.05 to 4% by weight, more preferably 0.05 to 3% by weight, and most preferably 0.05 to 2% by weight, based on the total weight of the reaction mixture containing components A, B, C and optionally D.;

[0021] In addition to stabilizers, catalysts or mixtures of different catalysts can also be used as component D, and in most cases amines or N-containing heterocycles are added as component D. The amine can be a primary, secondary or tertiary amine. The amine is preferably a tertiary amine. The amine can be an aromatic or aliphatic amine or a heterocyclic amine. Examples of amines and N-containing heterocycles for use in this process can be pyridine and piperidine. Examples of amines and N-containing heterocycles preferably used in this process are N-methylimidazole, pyridine, 2-methylimidazole, dimethylaminopyridine, triethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, diaminobicyclooctane, p-dimethylaminopyridine, p-pyrrolidinylpyridine, N,N-benzyldimethylamine, N-ethylmorpholine, 1-(2-hydroxypropyl)imidazole, 2-hydroxyethylpiperazine, 1,4-bis(2-hydroxyethyl)piperazine, N,N-dimethylcyclohexylamine, tris[3-(dimethylamino)propyl]-hexahydro-s-triazine. The following catalysts are preferably used: N-methylimidazole, pyridine, 2-methylimidazole, dimethylaminopyridine, triethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, p-dimethylaminopyridine and p-pyrrolidinylpyridine. In a particularly preferred embodiment, N-methylimidazole is used, which is both a tertiary amine and an N-containing heterocycle. Combinations of different catalysts can also be used. The amount of catalyst in the reaction mixture ranges from 0.01 to 5% by weight, preferably 0.05 to 4% by weight, more preferably 0.05 to 3% by weight, and most preferably 0.05 to 2% by weight, based on the total weight of the reaction mixture.

[0022] The functionalized partially hydrolyzed polyvinyl acetate particularly contains one or more units selected from the following units (Ia)-(Id) as functionalized vinyl alcohol units:

[0023]

[0024] wherein R1, R2 and R3 are independently hydrogen, a linear or branched aliphatic or heteroaliphatic group having 1 to 12 carbon atoms or an alicyclic, heterocyclic or aromatic group having 3 to 12 carbon atoms, and wherein X is a linear or branched or cyclic aliphatic or heteroaliphatic group having 1 to 12 carbon atoms or an alicyclic, heterocyclic or aromatic group having 3 to 12 carbon atoms, Y is O or S and Z is N-R4, S or O, where R4 is hydrogen, a linear or branched aliphatic or heteroaliphatic group having 1 to 12 carbon atoms or an alicyclic, heterocyclic or aromatic group having 3 to 12 carbon atoms.

[0025] In another embodiment, R1 and R2 are hydrogen and R3 is hydrogen, a linear or branched aliphatic or heteroaliphatic group having 1 to 12 carbon atoms, or an alicyclic, heterocyclic or aromatic group having 3 to 12 carbon atoms, and wherein X is a linear, branched or cyclic aliphatic or heteroaliphatic group having 1 to 12 carbon atoms, or an alicyclic, heterocyclic or aromatic group having 3 to 12 carbon atoms, Y is O or S and Z is N-R4, S or O, where R4 is hydrogen, a linear or branched aliphatic or heteroaliphatic group having 1 to 12 carbon atoms, or an alicyclic, heterocyclic or aromatic group having 3 to 12 carbon atoms. Preferably, R1 and R2 are hydrogen and R3 is a linear aliphatic group having 1 to 6 carbon atoms. More preferably, R1 and R2 are hydrogen and R3 is methyl or ethyl. X is preferably O.

[0026] In addition to vinyl alcohol units, vinyl acetate units and functionalized units, the functionalized polyvinyl acetate products obtained by the process of the present invention may optionally contain additional units incorporated during the polymerization of vinyl acetate and / or incorporated by post-polymerization reactions. These other units may be derived from other compounds bearing vinyl units, such as α-olefins, such as ethylene and propylene; (meth)acrylic acid and its salts; (meth)acrylates, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate and octadecyl (meth)acrylate; (meth)acrylamide; (meth)acrylamide derivatives, such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, diacetone(meth)acrylamide, (meth)acrylamidopropylsulfonic acid and its salts, (meth)acrylamidopropyldimethylamine and its salts or quaternary salts, and N-hydroxymethyl(meth)acrylamide and its derivatives; vinyl ethers, such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, dodecyl vinyl ether and stearyl vinyl ether; nitriles, such as acrylonitrile and methacrylonitrile; vinyl halides, such as vinyl chloride and vinyl fluoride; vinylidene halides, such as vinylidene chloride and vinylidene fluoride; allyl compounds, such as allyl acetate, allyl alcohol, allyl, allyl chloride and 3,4-diacetoxy-1-butene, 3,4-dihydroxy-1-butene, 1,4-diacetoxy-1-butene and 1,4-dihydroxy-1-butene; unsaturated dicarboxylic acids, such as maleic acid, itaconic acid and fumaric acid, and their salts or their esters; vinylsilyl compounds, such as vinyltrimethoxysilane; isopropyl acetate; etc. The functionalized partially hydrolyzed polyvinyl acetate of course has the general structure of the starting polymer. The structure of the functionalized polyvinyl acetate product can be syndiotactic, isotactic, atactic, linear, cyclic, branched, grafted or dendritic or a combination thereof. It is possible to obtain statistical copolymers as well as alternating or block copolymers. The functionalized polyvinyl acetate product may be insoluble, soluble in organic solvents or aqueous solutions or a combination thereof. The functionalized polyvinyl acetate product is preferably soluble, dispersible or emulsifiable in water or aqueous solutions.

[0027] In another embodiment, the degree of functionalization of the functionalized polyvinyl acetate product ranges from 0.01 to 99.9 mol%, preferably from 0.1 to 30 mol%, more preferably from 0.5 to 20 mol%, most preferably from 0.5 to 10 mol%, and in specific cases from 0.5 to 5 mol%, based on all monomer units of the functionalized partially hydrolyzed polyvinyl acetate.

[0028] In another embodiment, the degree of hydrolysis of the partially hydrolyzed polyvinyl acetate after functionalization is in the range of 0.01 to 99.8 mol%, preferably in the range of 50 to 99 mol%, more preferably in the range of 60 to 95 mol%, and most preferably in the range of 70 to 90 mol%, based on all the monomer units contained in the functionalized partially hydrolyzed polyvinyl acetate.

[0029] In a further embodiment, the viscosity of the functionalized polyvinyl acetate polymer (measured as a 4 wt% aqueous solution) is in the range of 0.1 to 50 mPa s, preferably in the range of 1 to 30 mPa s, and more preferably in the range of 2 to 10 mPa s.

[0030] Steps a) and b) are optional. In some cases it may be advantageous to dry the starting materials and remove water or residual solvents to avoid unwanted reactions and / or bubble formation. For drying, all procedures known to those skilled in the art can be used. The drying procedures can be selected from heating, vacuum treatment, treatment with water scavengers, spray drying, freeze drying, and any combination thereof.

[0031] It may also be advantageous to premix two or more starting materials to improve homogeneity. For mixing, all methods known to those skilled in the art can be used. The mixing procedures can be selected from dry mixing, coprecipitation, melt mixing, solution mixing, spraying of one component onto the particles of another component, spraying of a solution of one or more components onto the particles of another component followed by optional removal of the solvent, and combinations thereof. Mixing by incorporating a liquid into a solid or a solid into a liquid may be advantageous and reduce the number of inlets of the device capable of heating and mixing. In one embodiment, the components are fed in such a way that a premix of all the components is used or a premix of some of the components is used, followed by the use of some other components.

[0032] In step c), a mixing device capable of heating and mixing components A, B, C, and optionally D and forming a melt is provided, and the starting materials are fed into the device using at least one feed inlet. According to the present invention, any method known to those skilled in the art for thermoplastic processing can be used. Correspondingly, any equipment known to those skilled in the art and suitable for this purpose can also be used. However, melt extrusion is preferred, and thus a melt extruder is preferably used.

[0033] In one embodiment, the device capable of heating and mixing the components and forming a melt is selected from a kneader, a (Buss) co-kneader, a single-screw extruder, a co-rotating or counter-rotating twin-screw extruder, and a multi-screw extruder. The selection of a suitable extruder screw is within the common knowledge of those skilled in the art, and its geometry must match the expected processing functions, such as introduction, conveyance, homogenization, melting, and compression.

[0034] In some embodiments, the extruder has a length-to-diameter ratio of from 20 to 150, preferably from 40 to 110, more preferably from 42 to 60. The extruder generally comprises at least a conveying element, and optionally other elements selected from mixing elements, kneading elements, back pumping elements, barrier elements, degassing elements, cooling elements, and any combination thereof. Some elements may also have different functions, such as degassing and mixing. The positions of the different elements along the extruder depend, for example, on the temperature profile or the feed sequence or a combination thereof. The following steps are preferably used:

[0035] The components can be fed in the form of a premix of all components or first a premix of some components is fed, followed by the feeding of other components.

[0036] In a preferred embodiment, the feeding of the components is carried out successively, with polyvinyl acetate being fed first. Some preferred sequences of feeding the components (in the order shown in parentheses) are as follows:

[0037] a. (1) Polyvinyl acetate, then (2) stabilizer, then (3) catalyst, then (4) reactive compound;

[0038] b. (1) Polyvinyl acetate mixed with a catalyst, then (2) stabilizer and (3) reactive compound;

[0039] c. (1) Polyvinyl acetate mixed with a catalyst, a stabilizer, and a reactive compound;

[0040] d. (1) Polyvinyl acetate and stabilizer fed simultaneously, then (2) catalyst and (3) reactive compound;

[0041] e. (1) Polyvinyl acetate mixed with a stabilizer, then (2) catalyst and (3) reactive compound;

[0042] f. (1) Polyvinyl acetate mixed with a portion of the stabilizer, then (2) catalyst and (3) reactive compound mixed with a portion of the stabilizer;

[0043] g. (1) Polyvinyl acetate, then (2) catalyst and (3) reactive compound mixed with a stabilizer;

[0044] h. (1) Polyvinyl acetate, then (2) polyvinyl acetate mixed with a stabilizer and (3) catalyst, then (4) reactive compound;

[0045] i. (1) Polyvinyl acetate, then (2) catalyst mixed with a stabilizer and (3) reactive compound;

[0046] j. (1) Polyvinyl acetate mixed with a stabilizer and a catalyst, and then (2) a reactive compound; or

[0047] k. (1) Polyvinyl acetate and a stabilizer, then (2) polyvinyl acetate mixed with a catalyst, and then (3) a reactive compound.

[0048] It is preferred to use the sequences d., e., f., g. or j. above, and most preferably sequences d. or e. Advantageously, the stabilizer is evenly distributed within the polyvinyl acetate before adding any reactive compound to provide protection. It is preferred to evenly distribute the catalyst before adding the reactive compound to achieve uniform functionalization. When the catalyst is added after the reactive compound, a high local concentration will be generated, which is not conducive to a uniform reaction. In the case of e., the synchronous addition of polyvinyl acetate and stabilizer as described in d. saves an additional mixing step.

[0049] The feeding of the components can be carried out in different sections of the device according to the nature of the components and the order of addition. The position of the feeding element can also depend on the temperature reached at a specific position in the device. Suitable feeding units can be used to feed liquids and solids.

[0050] For reactions that generate by-products, such as condensation reactions, it is advantageous to remove at least part of these. The reactions used in the present invention are mainly condensation reactions, and the condensates can be removed by a degassing element, because at the temperatures used, most condensates, such as water or (meth)acrylic acid, are volatile.

[0051] During step c), the raw materials are mixed and heated to form a homogeneous melt, and the temperature is raised from room temperature to the temperature at which the polymer begins to soften and / or flow. In step d), the temperature can be further raised to the temperature at which the reactive compound begins to react with the OH- and / or OAc-groups of the partially hydrolyzed polyvinyl acetate. The temperature can be further increased to increase the reaction rate, but it must be kept below the temperature at which degradation and / or unwanted side reactions occur. During step c), the temperature may also reach the level at which the desired reaction begins, which may then shorten step d). The use of a catalyst can lower the reaction temperature, increase the reaction rate and help to suppress unwanted side reactions. The temperature of different zones of the extruder barrel is selected in the range from 0 °C to 270 °C, preferably in the range from 10 °C to 260 °C, more preferably in the range from 15 °C to 250 °C, and most preferably in the range from 15 °C to 230 °C. The feed section of the extruder is usually cooled to 10 to 25 °C and the temperature is gradually increased over a distance of 2D - 20D to the extruder temperature of 70 to 270 °C, preferably 100 °C to 240 °C, more preferably 160 °C to 230 °C, and most preferably 180 °C to 210 °C and maintained until the end of the extruder. Optionally, the temperature is gradually reduced at the end of the extruder to lower the melt temperature before the melt exits the extruder. The temperature of the extruder die is adjusted according to common sense to ensure smooth extrusion of the melt.

[0052] When the reaction has ended, the mixture can be actively cooled in an optional cooling step c). This can be advantageous, for example, when the reaction should be stopped or inhibited at a certain stage or when the mixture needs to be packaged into heat-sensitive containers. Cooling can be carried out by any method known to the person skilled in the art. Examples of cooling methods used are, for example, cooling with a cooling element connected to the extruder (wherein the element can be cooled with water or other coolant), cooling rolls, cooling belts or passing the extruded material through a liquid cooling bath (for example a liquid cooling bath filled with water or other liquid), or spraying a coolant or blowing a gas (preferably air) onto the mixture, or a combination thereof.

[0053] In some cases, it may be appropriate to carry out a shaping step before the cooling step, thereby forming one or more strands or profiles, films, tapes, plates, tubes, rods or pellets. The formation of pellets can be achieved, for example, by cutting the extruded material directly at the extruder die or by cutting the shaped profile. For cutting, a rotating blade can be used. Dies of corresponding form can be used for shaping and / or cutting of those. A combination of shaping and cooling can also be used, such as underwater pelletizing.

[0054] Optionally, further steps can be carried out after cooling. These steps are selected from grinding, cutting, drying, mixing, dissolving, dispersing, calendering, laminating, shaping, pelletizing of the extrudate and any combination thereof.

[0055] The functionalized polyvinyl acetate obtained by the method according to the invention can be used as a binder, crosslinking agent, functional coating (such as a barrier layer), hardener, modifier, adhesive or a combination thereof.

[0056] The functionalized polyvinyl acetate obtained by the method according to the invention can be used for producing a laminated composition, which comprises the steps of:

[0057] i) providing at least one functionalized partially hydrolyzed polyvinyl acetate obtained by the above method,

[0058] ii) metering and mixing the functionalized partially hydrolyzed polyvinyl acetate with other components to form a fluid mixture,

[0059] iii) superimposing the mixture on a substrate and

[0060] iv) optional further steps.

[0061] In step i), at least one functionalized polyvinyl acetate obtained by the method according to the invention or a mixture of these polymers is provided, and in the next step ii), it is metered and mixed with other components to form a fluid mixture. These methods can be dry mixing, stirring, dissolving, dispersing, emulsifying, melting, extrusion and any combination thereof. This can be carried out using any method known to those skilled in the art. Extrusion and dissolution or dispersion are preferably used. The fluid mixture can be a melt, solution, suspension, emulsion or any combination thereof. In some cases, it may be advantageous to remove part of the mixture, for example by evaporation of the solvent to increase the solids content, or by filtration to remove unwanted particles.

[0062] In step iii), subsequently, the fluid mixture is superimposed on the substrate using methods known to those skilled in the art, such as by extrusion through a die, coating, laminating, calendering, spraying, evaporation, deposition and combinations thereof. Superimposition is preferably carried out by extrusion and / or coating. In some cases, the solvent can be removed to form a film, which is then laminated to the substrate. There is no limitation on the nature of the substrate, which can be three-dimensional, in the form of a film or sheet, or in the form of fibers, rods or tubes or a combination thereof. The substrate can be metal, natural or artificial polymer, wood, paper, ceramic, stone or a combination thereof. The substrate is preferably a metal or polymer film or sheet.

[0063] In the optional further step iv) selected from drying, cooling, laminating, applying an additional layer, shaping, cutting and any combination thereof, the laminated composition can be adapted to its final use.

[0064] A process for producing a functionalized partially hydrolyzed polyvinyl acetate comprising vinyl alcohol, vinyl acetate and functionalized vinyl alcohol units, by reacting in the melt a partially hydrolyzed polyvinyl acetate as component A, a reactive compound having at least one ethylenically unsaturated group and at least one reactive group reactive towards a hydroxyl or acetate group as component B, in the presence of at least one stabilizer as component C and optionally in the presence of a catalyst as component D.

[0065] The present invention also relates to a process for producing a layered composition comprising a functionalized partially hydrolyzed polyvinyl acetate, which comprises the steps of:

[0066] a) providing

[0067] A) a partially hydrolyzed polyvinyl acetate as component A,

[0068] B) a reactive compound having at least one ethylenically unsaturated group and at least one reactive group reactive towards a hydroxyl or acetate group as component B,

[0069] C) at least one stabilizer as component C, and

[0070] D) optionally, a catalyst as component D,

[0071] and optionally drying one or more of components A, B, C and optionally D,

[0072] b) optionally premixing at least two of components A, B, C and optionally D,

[0073] c) feeding said components into a mixing device capable of heating, melting and mixing components A, B, C and optionally D,

[0074] d) heating, melting and mixing components A, B, C and optionally D in said device to produce a melt and reacting component A in B in the melt,

[0075] e) metering and mixing further components to form a fluid mixture,

[0076] f) superimposing said mixture on a substrate and

[0077] g) optional further steps.

[0078] In this method, steps a) to d) correspond to steps a) to d) of the above method and are carried out using the same methods and conditions as described above. In step e), further components are metered in and mixed with the functionalized partially hydrolyzed polyvinyl acetate obtained in the previous step. Metering and mixing of components A, B, C and D are carried out as described above and preferably a single extruder is used for all mixing and reaction steps. Feeding of solids and / or liquids can be carried out at different locations and in different sequences.

[0079] The further components are selected from further polymers, fillers, plasticizers, anti-blocking agents, monomers, additives (such as stabilizers, dyes), stabilizers, crosslinking agents, binders, chromogenic compounds, dyes, pigments, antioxidants, initiators, photoinitiators and combinations thereof.

[0080] As further polymers and binders, those which are soluble, dispersible or emulsifiable in aqueous solutions, organic solvents or combinations of both are used. Suitable polymeric binders are those conventionally used for the production of letterpress printing plates, such as fully or partially hydrolyzed polyvinyl esters, for example partially hydrolyzed polyvinyl acetate, polyvinyl alcohol derivatives, such as partially hydrolyzed vinyl acetate / alkylene oxide graft copolymers, or polyvinyl alcohol subsequently acrylated by polymer-analogous reactions as described, for example, in EP-A 0079514, EP-A 0224164 or EP-A 0059988, and mixtures thereof. Polyurethanes or polyamides soluble in water or water / alcohol mixtures are also suitable as polymeric binders as described, for example, in EP-A 00856472 or DE-A 1522444. These polymeric binders generally constitute 20 to 98, preferably 50 to 90% by weight of the total mixture.

[0081] As fillers, organic as well as inorganic particles can be used. Organic fillers can be artificial or natural polymers, pigments, waxes, carbon, wood or combinations thereof. For example, starches and derivatives, celluloses and derivatives, polyesters, polyamides, polystyrene (PS), polymethyl methacrylate (PMMA), poly(vinyl) ketones, polyoxymethylene (POM), polytetrahydrofuran or poly(α-methylstyrene) can be used. Inorganic fillers can be metals, alloys, salts, glass or combinations thereof. It is possible to use at least one or more selected from carbon black, feldspar, clay, silicon oxides, glass, quartz, silica, calcium carbonate, mica, talc and metal stearates, with silica and / or calcium carbonate being particularly preferably used. The fillers can be modified with reactive groups which may cause crosslinking or formation of bonds with other components, with (meth)acrylated particles being particularly preferred. Advantageously, if the fillers are present in particulate form, especially spherical or substantially spherical, the particle size is in the range of about 0.1 to 20 μm, preferably 0.5 to 15 μm, more preferably 1 to 10 μm.

[0082] The monomers suitable for preparing the mixtures are those which are photopolymerizable and compatible with the binder. Monomers of this type which are available usually have a boiling point above 100 °C. They usually have a molecular weight of less than 3000, preferably less than 2000.

[0083] Examples of suitable monomers are esters of acrylic and / or methacrylic acid with monohydric or polyhydric alcohols, such as butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, dodecyl (meth)acrylate, ethylene glycol di(meth)acrylate, butane-1,4-diol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methylpentane-1,5-diol di(meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hexane-1,6-diol di(meth)acrylate, 1,1,1-trimethylolpropane tri(meth)acrylate, di-, tri- and tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, pentaerythritol tetra(meth)acrylate and 3,12-dihydroxy-1,5,10,14-tetraoxatetradecane-1,14-diyl di(meth)acrylate. Other suitable compounds are vinyl esters of aliphatic monocarboxylic acids, such as vinyl oleate; divinyl ethers of alcohols, such as octadecyl vinyl ether and butane-1,4-diol divinyl ether; diesters of fumaric acid and maleic acid; and reaction products of oligobutadienes having terminal OH groups with maleic acid and / or methacrylic acid. Olefinic carbonylamino-N-methylidene ethers, such as ethylene glycol bis-, propylene glycol bis-, butane-1,4-diol bis-, diethylene glycol bis-, glycerol bis- or -tri- or pentaerythritol tetra-(methacrylamido-N-methylidene) ether or the corresponding acrylamido-N-methylidene ethers are also suitable. Among these monomers, 3,12-dihydroxy-1,5,10,14-tetraoxatetradecane-1,14-diyl di(meth)acrylate and ethylene glycol bis-, glycerol bis- and glycerol tri(methacrylamido-N-methylidene) ether are particularly advantageous. Epoxy- and urethane (meth)acrylates obtained, for example, by reacting bisphenol A diglycidyl ether with (meth)acrylic acid or by reacting mono- or diisocyanates with hydroxyalkyl (meth)acrylates and, if desired, with hydroxyl-containing polyesters or polyethers are also suitable. Derivatives of acrylamide and methacrylamide, such as their N-hydroxymethyl derivatives etherified with monohydric or polyhydric alcohols, such as ethylene glycol, glycerol, 1,1,1-trimethylolpropane or oligomeric or polymeric ethylene oxide derivatives are also suitable. The monomers can be added to the mixture in a wide concentration range of from 1 to 50% by weight, preferably in the range from 10 to 40% by weight, more preferably in the range from 15 to 35% by weight.

[0084] As initiator, a thermally activatable or photochemically activatable compound is used. Suitable thermal initiators are peroxides, hydroperoxides, azo or sulfur compounds, sulfur (elemental sulfur), sulfur chloride, sulfur dichloride, mercapto compounds, sulfide compounds, disulfide compounds, polysulfide compounds, thiuram compounds, thiocarbamic compounds and polyfunctional mercapto compounds, disulfide compounds, thiuram compounds, thiocarbamic compounds and polyfunctional mercapto compounds. Suitable compounds are, for example, dicumyl peroxide, α,α'-bis(tert-butylperoxy)diisopropylbenzene and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, selenium dimethyldithiocarbamate, pentaerythritol tetrakis(3-mercaptobutyrate), pentaerythritol tetrakis(thiopropionate), tris(3-mercaptobutoxyethyl) isocyanurate and dipentaerythritol hexakis(thiopropionate), 1,1'-azobis(cyclohexanecarbonitrile) and azobisisobutyronitrile.

[0085] Suitable photoinitiators or photoinitiator systems are those conventionally used in radiation-sensitive recording materials, such as free-radical photoinitiators, such as benzoin or benzoin derivatives, symmetrically or asymmetrically substituted benzil ketals, such as benzil dimethyl ketal or benzil 1-methyl 1-ethyl ketal, diarylphosphine oxides, such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide or 2,6-dimethoxy-benzoyl diphenylphosphine oxide, ethyl 2,4,6-trimethyl-benzoyl phenylphosphinate or acyl diarylphosphine oxides, diacylphosphine oxides or substituted and unsubstituted quinones, such as ethyl anthraquinone, benzanthraquinone, benzophenone or 4,4'-bis(dimethylamino)benzophenone. Triazines and hexaarylbiimidazoles are also suitable.

[0086] They can be used alone or as a mixture with a co-initiator, such as ethyl anthraquinone with 4,4'-bis(dimethylamino)benzophenone or diacylphosphine oxide with a tertiary amine or phosphine, such as triphenylphosphine. The photoinitiator is usually included in the radiation-sensitive mixture in an amount of 0.1 to 10, preferably 0.2 to 5% by weight, based on the total of all components in the mixture.

[0087] As a plasticizer, one or a combination of the following compounds can be used: polyethylene glycol, glycerol, ethylene glycol, N-alkyl-benzenesulfonamide, phthalate and their mixtures, aliphatic acid esters, such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, octylcapryl phthalate, dicyclohexyl phthalate, ditridecyl phthalate, butyl benzyl phthalate, diisodecyl phthalate, diallyl phthalate; glycol esters, such as dimethyl glycol phthalate, ethylphthalylethylglykolate, methylphthalylethylglykolate, butylphthalylbutylglykolate or triethylene glycol dioctanoate; phosphate esters, such as tricresyl phosphate or triphenyl phosphate; aliphatic diesters, such as diisobutyl adipate, dioctyl adipate, dimethyl sebacate, dibutyl sebacate, dioctyl azelate or dibutyl maleate; pentaerythritol polyoxyethylene ether; glycidyl methacrylate; triethyl citrate; glyceryl triacetate and butyl laurate. The concentration of the plasticizer is 1 to 30% by weight of the mixture, preferably 1 to 20% by weight, more preferably 1 to 15% by weight, and most preferably 3 to 10% by weight.

[0088] In addition, additional auxiliaries and additives in an amount of 0.0001 - 2% by weight can be used, such as suitable dyes, pigments or photochromic additives. They are used to control the exposure properties, for identification, for directly monitoring the exposure result or for aesthetic purposes. The selected prerequisite is that they do not interfere with the photopolymerization of the mixture. For example, soluble phenazinium, phenoxazinium, acridinium and phenothiazinium dyes, such as Neutral Red (C.I. 50040), Safranine T (C.I. 50240), Rhodanil Blue, salts or amides of Rhodamine D (Basic Violet 10, C.I 45170), Methylene Blue B (C.I. 52015) or Solvent Black 3 (C.I. 26150) are suitable. These dyes can also be used together with a sufficient amount of a reducing agent which does not reduce the dye in the absence of actinic light but can reduce the dye in the excited electronic state during exposure. Examples of such mild reducing agents are ascorbic acid, anethole, thiourea or hydroxylamine derivatives, especially salts of N-nitroso-cyclohexylhydroxylamine, preferably potassium, calcium and aluminum salts. An addition amount of 3 to 10 times the amount of the dye has proven useful in many cases. As stabilizers and antioxidants, the compounds described above can be added, and their concentration is in the range of 0.01 to 5% by weight, preferably 0.1 to 3% by weight, more preferably 0.1 to 2% by weight based on the weight of the mixture.

[0089] In a preferred embodiment, further components are metered into the same mixing device, in particular the same extruder used in steps c) and d) above. That is, steps c), d) and e) are carried out in the same mixing device.

[0090] In step f), the mixture is superimposed on the substrate using methods known to those skilled in the art, such as extrusion through a die, calendering, laminating and any combination thereof, on the substrate as described above for step iii). Superimposition is preferably achieved by extrusion through a slit die or calendering the melt on or between the substrates.

[0091] Examples of suitable dimensionally stable substrates are plates, sheets and conical and cylindrical sleeves made of metals (such as steel, aluminum, copper or nickel), or plastics (such as polyethylene terephthalate, polybutylene terephthalate, polyamide and polycarbonate), woven and non-woven fabrics such as fiberglass fabrics, and composite materials comprising fiberglass and plastics.

[0092] Particularly suitable dimensionally stable substrates are dimensionally stable substrate sheets and metal sheets, such as polyethylene or polyester sheets, or steel or aluminum sheets. These substrate sheets are typically 50 to 1100 μm, preferably 75 to 400 μm, for example about 250 μm thick. These substrate sheets can be coated on the face of the substrate sheet facing the mixture with a thin adhesion-promoting layer (for example a layer 1-5 μm thick).

[0093] Between or during steps d), e) and f), the temperature can be changed to, for example, adjust the viscosity or prevent degradation of the components. In most cases, the temperature can be lowered, but it is also possible that the temperature must be increased, for example when adding a compound with a high melting or softening temperature.

[0094] In an optional further step g), which can be selected from drying, cooling, laminating, applying additional layers, shaping, cutting and any combination thereof, the layered composition can be adapted to its final use. In the optional step g), additional layers, such as cover sheets, mask layers or barrier layers, are preferably applied, for example by laminating or coating, the resulting layered composite is cut into the desired shape or mounted on a flat or cylindrical carrier.

[0095] The layered composition can be used as relief precursors or coated paper. The relief precursors can be further processed and used as flexographic printing plates, letter pressplates, tampon press plates, direct (laser) engraveable plates, gravure plates, intaglio plates, mater plates or microfluidic devices.

[0096] The present invention generally relates to the following embodiments:

[0097] 1. A process for producing a functionalized partially hydrolyzed polyvinyl acetate comprising vinyl alcohol, vinyl acetate and functionalized vinyl alcohol units by reacting in the melt a partially hydrolyzed polyvinyl acetate as component A with a reactive compound having at least one ethylenically unsaturated group and at least one reactive group reactive towards a hydroxyl or acetate group as component B in the presence of at least one stabilizer as component C and in the presence of at least one catalyst selected from tertiary amines and N-containing heterocycles as component D, the process comprising the steps of:

[0098] a) optionally drying one or more of components A, B, C and optionally D,

[0099] b) optionally premixing two or more of components A, B, C and optionally D,

[0100] c) Feed the components into a mixing device capable of heating, melting, and mixing components A, B, C, and optionally D.

[0101] d) Heat, melt, and mix components A, B, C, and optionally D in the device to produce a melt and cause components A and B to react in the melt.

[0102] e) Optionally cool or shape and cool the resulting mixture.

[0103] 2. The method according to embodiment 1, wherein in component A, the groups reactive with the hydroxyl or acetate groups are selected from isocyanate groups, isothiocyanate groups, epoxy groups, aziridine groups, sulfonyl halide groups, acyl halide groups, carboxylic anhydride groups, carboxylic acid groups, carboxylic ester groups, aldehyde groups, maleimide groups, N-hydroxysuccinimide ester groups, or any combination thereof.

[0104] 3. The method according to embodiment 1 or 2, wherein the functionalized partially hydrolyzed polyvinyl acetate contains one or more units selected from the following units (Ia)-(Id) as functionalized vinyl alcohol:

[0105]

[0106] wherein R1, R2, and R3 are independently hydrogen, a linear or branched aliphatic or heteroaliphatic group having 1 to 12 carbon atoms, or an alicyclic, heterocyclic, or aromatic group having 3 to 12 carbon atoms, and wherein X is a linear, branched, or cyclic aliphatic or heteroaliphatic group having 1 to 12 carbon atoms, or an alicyclic, heterocyclic, or aromatic group having 3 to 12 carbon atoms, Y is O or S, and Z is N-R4, S, or O, where R4 is hydrogen, a linear or branched aliphatic or heteroaliphatic group having 1 to 12 carbon atoms, or an alicyclic, heterocyclic, or aromatic group having 3 to 12 carbon atoms.

[0107] 4. The method according to any one of embodiments 1 to 3, wherein component B is (meth)acrylic acid or a (meth)acrylic acid derivative.

[0108] 5. The method according to embodiment 4, wherein the (meth)acrylic acid derivative is (meth)acryloyl halide, (meth)acrylate, or (meth)acrylic anhydride.

[0109] 6. The method according to any one of embodiments 1 to 5, wherein the mixing device is selected from a kneader, a co-kneader, a single-screw extruder, a co-rotating or counter-rotating twin-screw extruder, and a multi-screw extruder.

[0110] 7. The method according to any one of embodiments 1 to 6, wherein the feeding of the components is carried out successively, and the partially hydrolyzed polyvinyl acetate is fed first.

[0111] 8. A method according to any one of embodiments 1 to 7, wherein the extruder has a length-to-diameter ratio of 20 to 150.

[0112] 9. A method according to any one of embodiments 1 to 8, wherein the feeding of the components is carried out in different sections of the extruder.

[0113] 10. A method according to any one of embodiments 1 to 9, wherein the reaction temperature in step d) is 100 °C to 270 °C.

[0114] 11. A method according to any one of embodiments 1 to 10, wherein the cooling in step e) is carried out by a cooling element, a cooling roll, a cooling belt, a liquid bath, a cooling medium flow, a spray cooling medium, and / or gas cooling or a combination thereof.

[0115] 12. A method according to any one of embodiments 1 to 11, wherein a shaping step is carried out before the cooling step.

[0116] 13. A method according to any one of embodiments 1 to 12, wherein further steps carried out after step d) or e) are selected from grinding, cutting, drying, mixing, dissolving, dispersing, shaping of the extrudate, and any combination thereof.

[0117] 14. A method according to any one of embodiments 1 to 13, wherein the degree of hydrolysis of the partially hydrolyzed polyvinyl acetate is in the range of 50 to 99 mol%.

[0118] 15. A method according to any one of embodiments 1 to 14, wherein the amount of stabilizer in the reaction mixture is in the range of 0.01 to 5 wt%.

[0119] 16. A method according to any one of embodiments 1 to 15, wherein the amount of catalyst in the reaction mixture is in the range of 0.01 to 5 wt%.

[0120] 17. A method according to any one of embodiments 1 to 16, wherein the degree of functionalization of the functionalized partially hydrolyzed polyvinyl acetate is in the range of 0.5 to 20 mol%.

[0121] 18. A method for producing a layered composition comprising a functionalized partially hydrolyzed polyvinyl acetate, comprising the steps of:

[0122] a) providing

[0123] A) a partially hydrolyzed polyvinyl acetate as component A,

[0124] B) a reactive compound having at least one ethylenically unsaturated group and at least one reactive group reactive with a hydroxyl or acetate group as component B,

[0125] C) at least one stabilizer as component C, and

[0126] D) at least one catalyst selected from tertiary amines and N-containing heterocycles as component D,

[0127] and optionally drying one or more of components A, B, C and optionally D,

[0128] b) optionally premixing at least two of components A, B, C and optionally D,

[0129] c) feeding the components into a mixing device capable of heating, melting and mixing components A, B, C and optionally D,

[0130] d) heating, melting and mixing components A, B, C and optionally D in the device to produce a melt and reacting components A and B in the melt,

[0131] e) metering in further components and mixing them with the functionalized partially hydrolyzed polyvinyl acetate obtained in step d) to form a fluid mixture,

[0132] f) applying the mixture onto a substrate and

[0133] g) optional further steps.

[0134] 19. The method according to embodiment 18, wherein steps c), d) and e) are carried out in the same mixing device.

[0135] 20. The method according to embodiment 18 or 19, wherein the mixing device is selected from kneaders, co-kneaders, single-screw extruders, co-rotating or counter-rotating twin-screw extruders and multi-screw extruders.

[0136] 21. The method according to any one of embodiments 18 to 20, wherein the laminated composition is a letterpress precursor or coated paper. Detailed Description

[0137] Method:

[0138] Viscosity:

[0139] For this measurement, a 4 wt% solution in distilled water is prepared. The measurement is carried out in a falling ball viscometer according to DIN 53 015.

[0140] Degree of hydrolysis:

[0141] The degree of hydrolysis refers to the percentage of vinyl acetate units hydrolyzed to vinyl alcohol units and is calculated by the following equation. EV represents the ester value, which is the milligrams of KOH required to neutralize the acid released by hydrolysis of the ester in 1 gram of the substance and which is measured according to EN ISO 3681.

[0142] Degree of hydrolysis = 100 x (100 - 0.1535 x EV) / (100 - 0.0749 x EV)

[0143] Ester value (EV):

[0144] Weigh approximately 1 g of the starting partially hydrolyzed polyvinyl acetate into a 250 mL round-bottom flask and mix with 70 mL of distilled water, then heat under reflux until it dissolves. After cooling, it is neutralized with 0.1 N potassium hydroxide against phenolphthalein. When the neutralization is complete, add 50 mL of 0.1 N potassium hydroxide and boil the mixture under reflux for 1 hour. During heating, back-titrate the excess caustic solution with 0.1 N hydrochloric acid against phenolphthalein indicator until the color cannot be reproduced. A blank test is carried out simultaneously.

[0145] Ester value = a * b * 5.61 / E

[0146] a = milliliters of 0.1 N potassium hydroxide consumed

[0147] b = milliliters of 0.1 N potassium hydroxide consumed in the blank test

[0148] E = weighed amount (dry) of the starting partially hydrolyzed polyvinyl acetate l

[0149] Solubility test:

[0150] Weigh approximately 90 g of a distilled water / n-propanol (w%, 75 / 25) mixture into a 250 mL round-bottom flask and mix with 10 g of the functionalized partially hydrolyzed polyvinyl acetate with stirring, then heat to 80 °C for 4 hours. Thereafter, a visual assessment of the solution is carried out, specifically regarding clearance, turbidity, amount of particles, aggregation, or clumping.

[0151] Degree of functionalization:

[0152] The following describes the method for functionalizing partially hydrolyzed polyvinyl acetate with methacrylic acid (MAA). For other functionalizations, this method can be used accordingly. In the first step, the sample to be measured is purified to remove reaction residues, especially monomers. Thus, extract approximately 12 g of the sample with 200 g of acetone in a Soxhlet at 56 °C for 6 hours. Subsequently, they are dried under vacuum (approximately 100 mbar) at 70 °C for 2 hours. Prepare a 10 wt% solution from the dried sample using a 50 wt% n-propanol / 50 wt% water mixture and record the solids content. Weigh 5 g of this solution and 2 g of potassium hydroxide solution (aq. 2 mol / L) into a 50 mL test tube. The sample is tempered at 93 °C for 4 hours. After cooling to room temperature, the solution is neutralized by adding 3 g of HCl (2 mol / L).

[0153] Subsequently, the vial was closed and shaken at 450 U / min for 45 minutes using an IKA 130 Basic Rüttler (IKA). Then, 35 g of acetone containing decanol as an internal standard (1500 g acetone / 0.51 g 1-decanol) was added. The sample was mixed for 1.5 hours at 450 U / min using an IKA 130 Basic Rüttler (IKA). This solution was sampled into 2 mL GC vials and filtered using a 0.25 μm syringe filter. The vials were placed in an autosampler and analyzed using a TRACE 1300 GC (Thermo Fisher Scientific) with a TriPlus 100 LS gas chromatograph using Chromeleon software (version 7.2.). The values of methacrylic acid (MAA) and acetic acid (AA) were given in mg / g. An FFAP column (Chromatographie Service GmbH) with a length of 50 m, a coverage of 0.25 mm, at 220 °C and 175 kPa, an FID detector, and hydrogen (6.0, Air Liquide) as the carrier gas were used.

[0154] The analysis was carried out under the assumption that the molar amounts of methacrylic acid and acetic acid corresponded to the molar amounts of the corresponding units (vinyl acetate units and functionalized units) in the polymer, and the mole fractions of vinyl alcohol units, vinyl acetate units, and functionalized units totaled 100%. The values of methacrylic acid (mg / g) and acetic acid (mg / g) from the GC analysis were calculated using the total amount of the functionalized polymer (in g), from which the masses of m MAA and m AA were obtained. The calculations were performed as follows:

[0155] and and thus

[0156]

[0157] where

[0158] The degree of functionalization in % was:

[0159]

[0160] Examples

[0161] Reactive extrusion experiments were carried out using a Leistritz ZSE 27HP twin-screw extruder with a screw diameter of 27 mm and an L / D ratio of 44. The length of one zone is 4D, so the extruder has 11 zones. Raw materials were fed in zones 1 and 2. Vacuum was applied in zone 10 to remove volatiles. The following temperature profile was used for all experiments: zones 1 - 3: 15 °C / 50 °C / 120 °C, zones 4 - 11 190 °C. The die temperature was set at 190 °C. The extruder screw profile was configured with conveying elements and kneading modules to uniformly melt and mix all components with minimal shear according to the common knowledge known to those skilled in the art. Solids were added to the extruder in zone 1, each using a separate gravity feeder. Liquids were added in zone 2, each using a separate feed pump.

[0162] Strands with an extrusion diameter of 3 mm were cooled by a combination of water and air cooling. After cooling, the strands were cut into pellets using a strand cutter.

[0163] For Examples 1 - 8, the KURARAY POVAL polymer was dried in a vacuum oven at 50 °C and 50 mbar for 1 day before being subjected to extrusion.

[0164] Example 1 (comparative)

[0165] KURARAY POVAL 5 - 74 with 74 mol% degree of hydrolysis was extruded with 5 wt% methacrylic anhydride at a screw speed of 200 rpm and a throughput of 15 kg / h. The 10 wt% solution showed good solubility and was clear. The degree of functionalization was determined to be 1.15 mol%.

[0166] Example 2 (comparative)

[0167] KURARAY POVAL 5 - 74 was extruded with 5 wt% methacrylic anhydride and 1 wt% N - methylimidazole at a screw speed of 200 rpm and a throughput of 15 kg / h. The 10 wt% solution showed good solubility and was slightly turbid. The degree of functionalization was determined to be 1.61 mol%.

[0168] Example 3 (comparative)

[0169] KURARAY POVAL 5 - 74 was extruded with 5 wt% methacrylic anhydride and 2 wt% N - methylimidazole at a screw speed of 200 rpm and a throughput of 15 kg / h. The 10 wt% solution showed good solubility and was slightly turbid. The degree of functionalization was determined to be 1.59 mol%.

[0170] Example 4

[0171] KURARAY POVAL 5-74 was extruded together with 5 wt% methacrylic anhydride and 1 wt% BHT at a screw speed of 200 rpm and a throughput of 15 kg / h. The 10 wt% solution showed good solubility and was slightly turbid. The degree of functionalization was determined to be 0.81 mol%. Although the degree of functionalization was slightly lower than that of Example 1 without stabilizer, it indicated that it was possible to achieve a comparable level of functionalization in the presence of stabilizers.

[0172] Example 5

[0173] KURARAY POVAL 5-74 was extruded together with 5 wt% methacrylic anhydride, 2 wt% N-methylimidazole and 1 wt% BHT at a screw speed of 200 rpm and a throughput of 15 kg / h. The 10 wt% solution showed good solubility and was slightly turbid. The degree of functionalization was determined to be 1.78 mol%.

[0174] It is obvious from the results of Examples 1 to 5 that the addition of stabilizers also has a positive effect on the degree of functionalization in the presence of catalysts. In addition, the reaction is achieved in a continuous and faster manner, requiring fewer process steps and without any additional plasticizers, solvents or unwanted impurities.

[0175] Example 6

[0176] KURARAY POVAL 4-88 with a degree of hydrolysis of 88 mol% was extruded together with 5 wt% methacrylic anhydride, 2 wt% N-methylimidazole and 1 wt% BHT at a screw speed of 200 rpm and a throughput of 15 kg / h. The degree of functionalization was determined to be 1.24 mol%.

[0177] Example 7

[0178] KURARAY POVAL 3-83 with a degree of hydrolysis of 83 mol% was extruded together with 5 wt% methacrylic anhydride, 2 wt% N-methylimidazole and 1 wt% BHT at a screw speed of 200 rpm and a throughput of 15 kg / h. The degree of functionalization was determined to be 1.79 mol%.

[0179] Example 8

[0180] KURARAY POVAL 8-88 with a degree of hydrolysis of 88 mol% was extruded together with 5 wt% methacrylic anhydride, 2 wt% N-methylimidazole and 1 wt% BHT at a screw speed of 200 rpm and a throughput of 15 kg / h. The degree of functionalization was determined to be 0.81 mol%.

[0181] Example 9

[0182] KURARAY POVAL 5-82 with a degree of hydrolysis of 82 mol% was first extruded with 1 wt% N-methylimidazole at a screw speed of 250 rpm and a throughput of 27 kg / h. Subsequently, the resulting compound was extruded with a mixture of 7.5 wt% methacrylic anhydride and 2 wt% MEHQ at a screw speed of 200 rpm and a throughput of 15 kg / h. The degree of functionalization was determined to be 1.16 mol%.

[0183] Example 10

[0184] KURARAY POVAL 5-82 was blended with 1 wt% N-methylimidazole and 2 wt% BHT. The blending was carried out by dissolving N-methylimidazole and BHT in ethanol, and the solution was mixed with the polymer in a drum mixer and dried in a vacuum furnace under reduced pressure at 50 °C. The blend was then extruded with 7.5 wt% methacrylic anhydride at a screw speed of 200 rpm and a throughput of 15 kg / h. The degree of functionalization was determined to be 2.24 mol%.

[0185] Example 11

[0186] KURARAY POVAL 5-82 was first extruded with 1 wt% N-methylimidazole at a screw speed of 250 rpm and a throughput of 27 kg / h. Subsequently, the resulting compound was extruded with a mixture of 6 wt% methacrylic anhydride and 2 wt% MEHQ at a screw speed of 200 rpm and a throughput of 15 kg / h. The degree of functionalization was determined to be 1.76 mol%.

[0187] Example 12

[0188] KURARAY POVAL 5-82 was blended with 1 wt% N-methylimidazole. The blending was carried out by dissolving N-methylimidazole in ethanol, and the solution was mixed with the polymer in a drum mixer and dried in a vacuum furnace under reduced pressure at 50 °C. The blend was extruded with a mixture of 13 wt% methacrylic anhydride and 1.5 wt% BHT at a screw speed of 200 rpm and a throughput of 15 kg / h. The degree of functionalization was determined to be 3.19 mol%.

[0189] Examples 6 to 12 show that polymers with other degrees of functionalization can be used in this method and that different orders of mixing components can have advantages.

[0190] Example 13

[0191] 45 parts by weight of the functionalized polymer from Example 8 were mixed with 20 parts of a polyvinyl alcohol-polyethylene glycol graft copolymer having a degree of hydrolysis of 97%, 33.18 parts of phenyl glycidyl ether acrylate, 1.5 parts of 2,2-dimethoxy-1,2-diphenylethanone, 0.3 part of potassium N-nitroso-cyclohexylhydroxylamine, 0.01 part of Safranin T (C.I. 50240), 0.01 part of Acriflavin (C.I. 46000) in 276 parts of water and 184 parts of n-propanol at 85 °C to form a homogeneous solution. The solution was coated onto a PET foil and dried at 60 °C to obtain a 600 μm thick layer. The resulting layer composition was exposed to actinic radiation through a structured mask and developed with water to form a printing plate.

[0192] Example 14

[0193] 55 parts of the functionalized polymer from Example 8 were mixed with 10 parts of polyethylene glycol 400 polymer, 32.7 parts of phenyl glycidyl ether acrylate, 1.5 parts of 2,2-dimethoxy-1,2-diphenylethanone, 0.3 part of potassium N-nitroso-cyclohexylhydroxylamine in an extruder at a temperature of 160 to 190 °C. The fluid mixture was applied onto a steel substrate using a slot die and cooled to room temperature to produce a 600 mm thick layer. The resulting layer composition was exposed to actinic radiation through a structured mask and developed with water to form a printing plate.

[0194] Example 15

[0195] Example 8 (50 parts) was repeated, but 15 parts of polyethylene glycol polymer, 33 parts of phenyl glycidyl ether acrylate, 1.5 parts of 2,2-dimethoxy-1,2-diphenylethanone, 0.3 part of potassium N-nitroso-cyclohexylhydroxylamine and 0.3 part of BHT were added in an additional feed section and mixed homogeneously. The fluid mixture was applied onto a steel foil using a slot die and cooled to room temperature to produce a 600 mm thick layer. The resulting layer composition was exposed to actinic radiation through a structured mask and developed with water to form a printing plate.

Claims

1. A method for producing a letterpress precursor comprising a functionalized partially hydrolyzed polyvinyl acetate, which comprises the following steps: a) Providing: Component A, which is selected from partially hydrolyzed polyvinyl acetates, wherein the degree of hydrolysis of the partially hydrolyzed polyvinyl acetate before functionalization is in the range of 50 to 99 mol%, based on all monomer units contained in the partially hydrolyzed polyvinyl acetate, Component B, which is selected from reactive compounds having at least one ethylenically unsaturated group and at least one reactive group reactive with a hydroxyl or acetate group, Component C, which is selected from at least one stabilizer, in an amount in the range of 0.05 to 5% by weight, based on the total weight of the reaction mixture containing Components A, B, C, and D, and Component D, which is selected from at least one catalyst selected from tertiary amines and N-containing heterocycles, And optionally drying one or more of Components A, B, C, and D, b) Optionally premixing at least two of Components A, B, C, and D, c) Feeding the components into a mixing device capable of heating, melting, and mixing Components A, B, C, and D, d) Heating, melting, and mixing Components A, B, C, and D in the device to produce a melt and reacting Components A and B in the melt, preferably without any additional plasticizer or solvent, e) Metering and mixing other components with the functionalized partially hydrolyzed polyvinyl acetate obtained in step d) to form a fluid mixture, f) Superimposing the fluid mixture on a substrate, preferably a metal or polymer film or sheet, and g) Optional further steps.

2. The method according to claim 1, wherein steps c), d), and e) are carried out in the same mixing device.

3. The method according to claim 1 or 2, wherein the mixing device is selected from kneaders, co-kneaders, single-screw extruders, co-rotating or counter-rotating twin-screw extruders, and multi-screw extruders.

4. The method according to any one of claims 1 to 3, wherein the method comprises premixing at least two of Components A, B, and C.

5. The method according to any one of claims 1 to 4, wherein the method comprises premixing at least two of Components A, B, C, and Component D.

6. The method according to any one of claims 1 to 5, wherein the method comprises feeding Components A, B, C, and Component D into an extruder.

7. The method according to any one of claims 1 to 6, wherein the step of melting and mixing Components A, B, C, and D to produce a melt and reacting Components A and B in the melt is carried out without any additional plasticizer.

8. The method according to any one of claims 1 to 7, wherein the step of heating, melting, and mixing Components A, B, C, and D in the device to produce a melt and reacting Components A and B in the melt is carried out without any solvent.

9. The method according to any one of claims 1 to 8, wherein superimposing the fluid mixture on the substrate is carried out by extrusion.

10. The method according to any one of claims 1 to 9, wherein the degree of hydrolysis of the partially hydrolyzed polyvinyl acetate before functionalization is in the range of 74 to 99 mol%, based on all monomer units contained in the partially hydrolyzed polyvinyl acetate.

11. The method according to any one of claims 1 to 10, wherein the relief precursor is further processed into a flexographic printing plate, a letterpress printing plate, a strip printing plate, a direct laser engraveable plate, a gravure printing plate, an intaglio printing plate, a master printing plate, or a microfluidic device.

12. The method according to any one of claims 1 to 11, wherein the relief precursor is further processed into a printing plate and developed with water.

13. The method according to any one of claims 1 to 12, wherein the monomer addition concentration is in the range of 10 to 40% by weight.

14. The method according to any one of claims 1 to 13, wherein a single extruder is used for all mixing and reaction steps.

15. The method according to any one of claims 1 to 14, wherein the relief precursor is further processed into a printing plate.

16. The method according to claim 15, wherein the relief precursor is processed and developed with water.

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