Vinyl alcohol-based block copolymer and method for producing the same

Abstract

To provide a vinyl alcohol-based block copolymer that, while having high water solubility, has a surface which shows high hydrophobicity when formed into a film, has excellent compatibility with a hydrophobic material, and shows high compatibility when alloyed with a hydrophobic material.SOLUTION: Provided is a vinyl alcohol-based block copolymer, comprising: a vinyl alcohol-based polymer block (A); and a vinyl alcohol-based block copolymer block (B) that comprises a vinyl alcohol-based monomer unit and an olefin-based monomer unit having a C5-20 long-chain alkyl group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a vinyl alcohol-based block copolymer and a method for producing the same, and more specifically to a vinyl alcohol-based block copolymer that has excellent water solubility, exhibits hydrophobicity on the surface when formed into a coating, and has excellent affinity with hydrophobic materials, and a method for producing the same. [Background technology]

[0002] Hydrophobic resin materials are commonly used as materials for films and fibers. However, highly hydrophilic materials are required for forming porous membranes used in the treatment of various aqueous liquids, such as for medical and industrial filtration and separation. Therefore, studies have been conducted to coat hydrophobic resin materials with hydrophilic materials or to alloy them with highly hydrophilic resins (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-29926 [Patent Document 2] Japanese Patent Application Publication No. 5-202240 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a hydrophilic material is coated onto a hydrophobic substrate, the affinity is low and adhesion is insufficient, which can cause the hydrophilic material to fall off during use. Furthermore, when hydrophobic groups are introduced into the hydrophilic material in an attempt to increase adhesion to the hydrophobic material, water solubility is significantly reduced, making it impossible to coat with an aqueous solution. Furthermore, when hydrophobic and hydrophilic materials are alloyed, mutual exclusion occurs due to low affinity, resulting in an unstable mixed phase or local separation of the materials, which can significantly reduce the mechanical properties of the material and prevent sufficient hydrophilicity from being achieved.

[0005] Under these circumstances, the present invention aims to provide a vinyl alcohol-based block copolymer that has high water solubility, but when formed into a coating, exhibits hydrophobicity on its surface, has excellent affinity with hydrophobic materials, and has high affinity when alloyed with hydrophobic materials. [Means for solving the problem]

[0006] However, in view of the above circumstances, the present inventors have conducted extensive research and found that the above-mentioned problems can be solved by a vinyl alcohol-based block copolymer comprising a vinyl alcohol-based polymer block (A) and a vinyl alcohol-based copolymer block (B) containing vinyl alcohol-based monomer units and olefin-based monomer units having a long-chain alkyl group having 5 to 20 carbon atoms, thereby completing the present invention.

[0007] That is, the present invention has the following aspects. [1] A vinyl alcohol-based block copolymer having a vinyl alcohol-based polymer block (A) and a vinyl alcohol-based copolymer block (B) containing a vinyl alcohol-based monomer unit and an olefin-based monomer unit having a long-chain alkyl group having 5 to 20 carbon atoms. [2] The vinyl alcohol-based block copolymer according to [1], wherein the content of the olefin-based monomer units having a long-chain alkyl group having 5 to 20 carbon atoms is 0.1 to 20 mol % based on the total monomer units of the vinyl alcohol-based block copolymer. [3] The vinyl alcohol block copolymer according to [1] or [2], wherein the vinyl alcohol block copolymer has a number average molecular weight of 1,000 to 250,000. [4] The vinyl alcohol block copolymer according to any one of [1] to [3], wherein the degree of saponification of the vinyl alcohol block copolymer is 60 to 100 mol %. [5] A resin composition comprising at least a polyolefin resin and the vinyl alcohol block copolymer according to any one of [1] to [4]. [6] A permeation membrane comprising the resin composition according to [5]. [7] a step of polymerizing a vinyl ester-based monomer in the presence of a radical initiator and an organic cobalt complex to obtain a vinyl ester-based polymer block (A-1); a step of polymerizing an olefin-based monomer having a long-chain alkyl group having 5 to 20 carbon atoms and a vinyl ester-based monomer in the presence of a radical initiator and an organic cobalt complex to obtain a vinyl ester-based copolymer block (B-1); A method for producing a vinyl alcohol-based block copolymer, comprising the step of saponifying the obtained vinyl ester-based polymer block (A-1) and vinyl ester-based copolymer block (B-1) to obtain a vinyl alcohol-based block copolymer. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a vinyl alcohol-based block copolymer that has high water solubility, but when formed into a coating, exhibits hydrophobicity on its surface, has excellent affinity with hydrophobic materials, and has high affinity when alloyed with hydrophobic materials, and a method for producing the same. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below based on examples of embodiments for carrying out the present invention, but the present invention is not limited to the embodiments described below.

[0010] In this specification, "x and / or y (x and y are optional configurations)" means at least one of x and y, and can mean three possibilities: x only, y only, or x and y. In this specification, when the expression "X to Y" (X and Y are any numbers) is used, unless otherwise specified, it means "X or more and Y or less," as well as "preferably larger than X" or "preferably smaller than Y." In this specification, when it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also means that "it is preferably greater than X" or "it is preferably less than Y." For the numerical ranges described step by step in this specification, the upper limit value or lower limit value of a numerical range at a certain step can be arbitrarily combined with the upper limit value or lower limit value of a numerical range at other steps. Also, in the numerical ranges described in this specification, the upper limit value or lower limit value of the numerical range can be replaced with the value shown in the examples.

[0011] In this specification, "mainly having these structural units" means that among the structural units constituting the vinyl alcohol-based block copolymer of the present invention, the total content of the structural units of the vinyl alcohol-based polymer and the structural units of the olefin-based polymer having 5 to 20 carbon atoms is 50% by mass or more in all the structural units constituting the vinyl alcohol-based block copolymer of the present invention, preferably 55% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. Note that the total content may be 100% by mass. Also, in this specification, vinyl alcohol may sometimes be simply referred to as "PVA".

[0012] <<PVA-based block copolymer>> The PVA-based block copolymer according to one embodiment of the present invention (hereinafter sometimes referred to as "the present PVA-based block copolymer") is a block copolymer having a PVA-based polymer block (A) and a PVA-based copolymer block (B) containing a PVA-based monomer unit and an olefin-based monomer unit having a long-chain alkyl group with 5 to 20 carbon atoms.

[0013] The present PVA-based block copolymer contains the structural units of the PVA-based polymer and the structural units of the olefin-based polymer having 5 to 20 carbon atoms, and preferably mainly has these structural units.

[0014] The PVA-based polymer block (A) and the PVA-based copolymer block (B) are obtained by saponifying a vinyl ester-based polymer block and a vinyl ester-based copolymer block, and the PVA-based polymer block (A) contains a PVA-based monomer unit. The PVA copolymer block (B) contains a PVA monomer unit and an olefin monomer unit having 5 to 20 carbon atoms.

[0015] The PVA monomer units contained in the PVA polymer block (A) and the PVA copolymer block (B) are obtained by saponifying a vinyl ester monomer. Examples of the vinyl ester monomer include aliphatic vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate, and vinyl trifluoroacetate, and aromatic vinyl esters such as vinyl benzoate. Among these, aliphatic vinyl esters having 3 to 20 carbon atoms are preferred, more preferably 4 to 10 carbon atoms, and even more preferably 4 to 7 carbon atoms, with vinyl acetate being particularly preferred. These monomers may be used alone or in combination of two or more.

[0016] The olefinic monomer unit having 5 to 20 carbon atoms contained in the PVA copolymer block (B) is an unsaturated carbon having a long-chain alkyl group having 5 to 20 carbon atoms. The alkyl group may be linear or branched, and the number of carbon atoms in the alkyl group is preferably 8 to 19, and particularly preferably 12 to 18. When the alkyl group is a long-chain alkyl group, the hydrophobicity of the surface when formed into a coating film is improved. Specific examples of the olefin-based monomer unit having 5 to 20 carbon atoms include α-olefins such as 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-hexadecene, 1-octadecene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2,2,4-trimethyl-1-pentene, and 2-ethyl-1-hexene.

[0017] In the present PVA block copolymer, the content of the olefin monomer units having 5 to 20 carbon atoms relative to the total of the PVA monomer units and the olefin monomer units having 5 to 20 carbon atoms in the PVA copolymer block (B) is preferably 0.1 to 40 mol %, more preferably 0.5 to 30 mol %, and even more preferably 1 to 20 mol %. When the content of the olefin monomer units having 5 to 20 carbon atoms is within this range, the hydrophobicity of the surface when formed into a coating film tends to be improved. The content of the olefin monomer units having 5 to 20 carbon atoms relative to the total of the PVA monomer units and the olefin monomer units having 5 to 20 carbon atoms in the PVA copolymer block (B) can be measured, for example, by the method described in the Examples below.

[0018] In the present PVA block copolymer, the content of the olefin monomer units having 5 to 20 carbon atoms relative to the sum of all PVA monomer units and olefin monomer units having 5 to 20 carbon atoms (total monomer units of the PVA block copolymer) is preferably 0.1 to 20 mol%, more preferably 0.5 to 15 mol%, even more preferably 1 to 15 mol%, and particularly preferably 1 to 10 mol%. When the content of the olefin monomer units having 5 to 20 carbon atoms is within this range, the effects of the present invention tend to be more easily achieved. The content of the olefin monomer units having 5 to 20 carbon atoms relative to the sum of all PVA monomer units and olefin monomer units having 5 to 20 carbon atoms (total monomer units of the PVA block copolymer) can be measured, for example, by the method described in the Examples below.

[0019] The average saponification degree of the PVA block copolymer is preferably 60 mol% or more, more preferably 65 mol% or more, and even more preferably 70 mol% or more. If the average saponification degree is too low, hydrophilicity tends to decrease, and the upper limit of the average saponification degree is 100 mol%. The average degree of saponification can be measured, for example, by the method described in the Examples below.

[0020] The number average molecular weight (Mn) of the PVA block copolymer is preferably 1000 to 250000, more preferably 1500 to 200000, still more preferably 2000 to 150000, and particularly preferably 2500 to 100000. When the number average molecular weight (Mn) is within this range, the copolymer tends to have better water solubility. The number average molecular weight (Mn) of the present PVA block copolymer can be measured, for example, by the method described in the Examples below.

[0021] The weight-average molecular weight (Mw) of the PVA block copolymer is preferably 1,000 to 500,000, more preferably 5,000 to 400,000, still more preferably 5,000 to 300,000, and particularly preferably 10,000 to 250,000. When the weight-average molecular weight is within this range, the copolymer tends to have better water solubility. The weight average molecular weight (Mw) of the present PVA block copolymer can be measured, for example, by the method described in the Examples below.

[0022] The polydispersity of the present PVA block copolymer is preferably 1-10, more preferably 1.2-7, and even more preferably 1.5-5. The dispersity of the present PVA block copolymer can be measured, for example, by the method described in the Examples below.

[0023] The water contact angle on the surface of the coating of the PVA block copolymer is preferably 58° or more, more preferably 59° or more, and even more preferably 60° or more. The upper limit is usually 150°, and preferably 130°. The water contact angle of the coating of the PVA block copolymer can be measured, for example, by the method described in the Examples below.

[0024] This PVA-based block copolymer has superior water solubility and affinity with hydrophobic materials compared to PVA-based random copolymers having similar olefin-based monomer units with 5 to 20 carbon atoms.

[0025] <<Method for Producing PVA-based Block Copolymer>> As a method for producing the present PVA-based block copolymer, for example, a step of polymerizing a vinyl ester monomer in the presence of a radical initiator and an organic cobalt complex to obtain a vinyl ester polymer block (A-1), and a step of polymerizing an olefin monomer having a long-chain alkyl group with 5 to 20 carbon atoms and a vinyl ester monomer in the presence of a radical initiator and an organic cobalt complex to obtain a vinyl ester copolymer block (B-1). Then, a step of saponifying the obtained vinyl ester polymer block (A-1) and the vinyl ester copolymer block (B-1) containing an olefin monomer having a long-chain alkyl group with 5 to 20 carbon atoms and a vinyl ester monomer to obtain a PVA-based block copolymer, whereby a PVA-based block copolymer can be obtained. Hereinafter, the production method will be described in detail.

[0026] <Step of Obtaining Vinyl Ester Polymer Block (A-1)> The vinyl ester polymer block (A-1) is usually obtained by polymerizing a vinyl ester monomer. And by saponifying such a vinyl ester polymer block (A-1), it becomes a PVA-based polymer block (A).

[0027] Examples of the vinyl ester monomer include aliphatic vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate, vinyl trifluoroacetate, and aromatic vinyl esters such as vinyl benzoate. Among them, aliphatic vinyl esters having 3 to 20 carbon atoms are preferred, more preferably 4 to 10 carbon atoms, still more preferably 4 to 7 carbon atoms, and particularly preferably vinyl acetate. These can be used alone or in combination of two or more.

[0028] The polymerization method is preferably living radical polymerization, and polymerization is preferably carried out using a known radical polymerization initiator such as azobisisobutyronitrile, acetyl peroxide, benzoyl peroxide, or lauroyl peroxide in combination with a cobalt catalyst as a living radical control agent.

[0029] The radical polymerization initiator is preferably an azo-based polymerization initiator, more preferably 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), and the cobalt catalyst is preferably a divalent organic cobalt complex, more preferably cobalt(II) acetylacetonate.

[0030] The amount of the radical polymerization initiator added is preferably 0.00001 to 0.2 mol %, more preferably 0.00005 to 0.02 mol %, and even more preferably 0.0001 to 0.002 mol %, based on the total amount of the vinyl ester monomer and the radical polymerization initiator initially charged.

[0031] The amount of the living radical controller added is preferably 0.00001 to 0.1 mol %, more preferably 0.00005 to 0.01 mol %, and even more preferably 0.0001 to 0.001 mol %, based on the total amount of the vinyl ester monomer and the living radical controller initially charged.

[0032] The polymerization temperature is preferably 0 to 60° C., more preferably 10 to 50° C. The polymerization time is not particularly limited as it varies depending on the polymerization temperature, but polymerization is preferably continued until the polymerization rate reaches 10% or more, more preferably 15% or more, and even more preferably 20% or more.

[0033] In addition to the vinyl ester monomer, other unsaturated monomers may also be polymerized within the range that does not impair the effects of the present invention. The amount of other unsaturated monomers introduced into the PVA polymer block (A) is usually 20 mol % or less, preferably 10 mol % or less, and particularly preferably 5 mol % or less, with the lower limit being 0 mol %.

[0034] Examples of the other unsaturated monomers include unsaturated acids such as (meth)acrylic acid, crotonic acid, maleic acid, maleic anhydride, and itaconic acid, or their salts or mono- or di-alkyl esters; nitriles such as (meth)acrylonitrile; amides such as (meth)acrylamide; olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallylsulfonic acid, or their salts; alkyl vinyl ethers; N-acrylamidomethyltrimethylammonium chloride; allyl trimethylammonium chloride; dimethyl allyl vinyl ketone; N-vinyl pyrrolidone; vinyl chloride; vinylidene chloride; polyoxyethylene (meth)allyl ether; polyoxypropylene (meth)allyl ether; Examples of the alkyl ether include polyoxyalkylene (meth)allyl ethers such as methyl acrylate, polyoxyalkylene (meth)acrylates such as polyoxyethylene (meth)acrylate and polyoxypropylene (meth)acrylate, polyoxyalkylene (meth)acrylamides such as polyoxyethylene (meth)acrylamide and polyoxypropylene (meth)acrylamide, polyoxyethylene (1-(meth)acrylamide-1,1-dimethylpropyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine, 3,4-diacetoxybutene, etc. These may be used alone or in combination of two or more.

[0035] <Step of Obtaining Vinyl Ester Copolymer Block (B-1)> The vinyl ester copolymer block (B-1) is obtained by polymerizing a vinyl ester monomer and an olefin monomer having a long-chain alkyl group having 5 to 20 carbon atoms. Then, the vinyl ester copolymer block (B-1) is saponified to form the PVA copolymer block (B).

[0036] The vinyl ester monomer used in the polymerization of the vinyl ester copolymer block (B-1) can be the same as that described above for the vinyl ester polymer block (A-1).

[0037] Examples of the olefin monomer having a long-chain alkyl group having 5 to 20 carbon atoms (the alkyl group may be linear or branched) include α-olefins such as 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-hexadecene, 1-octadecene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2,2,4-trimethyl-1-pentene, and 2-ethyl-1-hexene. Among these, 1-octadecene is preferably used from the viewpoint of imparting hydrophobicity.

[0038] The vinyl ester copolymer block (B-1) is preferably polymerized by the same method as that described above for the vinyl ester polymer block (A-1).

[0039] Then, the vinyl ester polymer block (A-1) obtained by living polymerization and the vinyl ester copolymer block (B-1) prepared above are reacted to obtain a vinyl ester block copolymer.

[0040] The reaction temperature between the vinyl ester polymer block (A-1) and the vinyl ester copolymer block (B-1) is preferably 20 to 80°C, more preferably 30 to 70°C, and even more preferably 40 to 60°C.

[0041] The reaction time is not particularly limited as it varies depending on the reaction temperature, but is usually 10 minutes to 10 hours, and preferably 30 minutes to 8 hours. If necessary, a reaction terminator such as dinitrobenzene or diphenylethylene may be added to terminate the reaction.

[0042] <Saponification step to obtain PVA block copolymer> The vinyl ester polymer block (A-1) and the vinyl ester copolymer block (B-1) obtained above are saponified, but the saponification method is not particularly limited and can be any known method. That is, the saponification can be carried out using an alkali catalyst or an acid catalyst in a state where the vinyl ester polymer block (A-1) and the vinyl ester copolymer block (B-1) are dissolved in an alcohol or water / alcohol solvent. As the alkali catalyst, for example, hydroxides or alcoholates of alkali metals such as potassium hydroxide, sodium hydroxide, sodium methylate, sodium ethylate, potassium methylate, and lithium methylate can be used. Generally, transesterification using an alkali catalyst in an absolute alcohol solvent is preferably used in terms of reaction rate and ability to reduce impurities such as fatty acid salts. The saponification step is preferably carried out after the extraction step (extraction of the reaction product from the reaction solution) from the viewpoint of the purity of the present PVA block copolymer obtained.

[0043] The present PVA block copolymer can be obtained by saponifying the vinyl ester polymer block (A-1) and the vinyl ester copolymer block (B-1).

[0044] <Other ingredients> The PVA block copolymer may contain other components, such as other resin components, polymerization inhibitors, antioxidants, corrosion inhibitors, crosslinking accelerators, UV absorbers, plasticizers, pigments, stabilizers, fillers, and other additives, metals, and resin particles, as long as the effects of the present invention are not impaired. These may be used alone or in combination of two or more. Furthermore, small amounts of impurities contained in the raw materials for producing the constituent components may also be contained.

[0045] The content of the other components is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the PVA copolymer block. The lower limit is usually 0% by mass.

[0046] The present PVA-based block copolymer exhibits high hydrophilicity when alloyed with a hydrophobic material, and can therefore be used as a resin composition containing a hydrophobic polyolefin-based resin and the present PVA-based block copolymer.

[0047] Examples of the polyolefin resin include polyethylene resin, polypropylene resin, etc. These may be used alone or in combination of two or more kinds.

[0048] Examples of the polyethylene resin include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and resins obtained by modifying these polyethylene resins with unsaturated carboxylic acids or derivatives of unsaturated carboxylic acids.

[0049] Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, etc., as well as esters and anhydrides thereof, which may be used alone or in combination of two or more.

[0050] Examples of the derivatives of the unsaturated carboxylic acid include methyl acrylate, methyl methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, butyl methacrylate, glycidyl acrylate, glycidyl methacrylate, acrylamide, methacrylamide, sodium acrylate, and derivatives to which vinyl acetate, etc. are added. These may be used alone or in combination of two or more.

[0051] The melt flow rate (MFR) of the polyethylene resin (JIS K7210-1 Method A (2014), 190°C, load 2.16 kg) is usually 0.1 to 50 g / 10 min, preferably 0.3 to 20 g / 10 min, from the viewpoint of film formability.

[0052] The content ratio of the PVA block copolymer to the polyolefin resin (PVA block copolymer / polyolefin resin) is preferably 0.01 to 30, more preferably 0.03 to 20, and even more preferably 0.05 to 10, in mass ratio.

[0053] The particle size of the PVA block copolymer dispersed in the resin composition containing the polyolefin resin and the PVA block copolymer is preferably 5 μm or less, more preferably 2 μm or less. The particle size can be measured, for example, by the method described in the section on dispersibility determination in the Examples below.

[0054] The resin composition containing the polyolefin resin and the PVA block copolymer preferably has a breaking elongation of 150% or more, more preferably 200% or more, and even more preferably 250% or more. The upper limit is usually 400%. The breaking elongation can be measured, for example, by the method described in the Examples below.

[0055] <Application> This PVA-based block copolymer has excellent water solubility, and when formed into a coating, its surface exhibits hydrophobicity. It also has excellent affinity with hydrophobic materials, and when alloyed with hydrophobic materials, it exhibits high affinity, making it suitable for a wide range of applications in various fields, including medical and industrial fields. For example, it can be used favorably in osmosis membranes and water purification membranes. [Example]

[0056] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by mass.

[0057] Example 1 A PVA-based block copolymer was prepared through the following steps.

[0058] [Preparation of vinyl ester block copolymers] A flask equipped with a stirring blade was charged with 500 g of vinyl acetate, 0.48 g of cobalt(II) acetylacetonate as a living radical inhibitor, and 1.6 g of water. Nitrogen was then bubbled through for 30 minutes, followed by the addition of 2.4 g of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) as a radical polymerization initiator, and nitrogen was bubbled through for another 30 minutes. The mixture was heated under a nitrogen atmosphere while stirring, and the temperature of the reaction solution was adjusted to 30°C to allow polymerization. After 4 hours had passed since the start of the reaction, 110 g of 1-octadecene was dissolved in the same amount of methyl acetate and nitrogen was bubbled through for 15 minutes. The entire amount was then added to the flask, the temperature was raised to 40°C, and the mixture was allowed to react for another 4 hours. Thereafter, 2.4 g of diphenylethylene was added to terminate the reaction, and ethyl acetate and an aqueous solution of acetic acid (2%) were added and the aqueous layer was removed by a separation operation. The organic layer was then distilled off with an evaporator to remove the solvent. The resulting mixture was washed with hexane and dissolved in methanol, after which the remaining vinyl acetate and solvent were distilled off with an evaporator to obtain a vinyl ester-based block copolymer.

[0059] [Saponification of the reactant] The vinyl ester-based block copolymer and methanol were added to a flask, saponified with sodium hydroxide, washed with methanol, and then dried in a vacuum dryer at 50°C for 8 hours to obtain the desired PVA-based block copolymer (P-1). The resulting PVA block copolymer (P-1) had a number average molecular weight (Mn) of 48,000, a weight average molecular weight (Mw) of 99,600, and a degree of saponification of 99.7 mol %.

[0060] <Example 2> Polymerization was carried out in the same manner as in Example 1, except that the amount of 1-octadecene was 97.6 g and the reaction time after the introduction of the 1-octadecene solution was 3 hours, to obtain a vinyl ester-based block polymer. The vinyl ester-based block copolymer, methanol, and water were added to a flask, and the mixture was saponified with sodium hydroxide, washed with methanol, and then dried in a vacuum dryer at 50°C for 8 hours to obtain the desired PVA-based block copolymer (P-2). The resulting PVA block copolymer (P-2) had a number average molecular weight (Mn) of 20,600, a weight average molecular weight (Mw) of 60,500, and a degree of saponification of 79.1 mol %.

[0061] <Comparative Example 1> [Preparation of unmodified PVA] 90 g of vinyl acetate and 108 g of methanol were placed in a flask equipped with a stirring blade, and after the temperature was raised and refluxing was confirmed, 0.09 g of azobisisobutyronitrile was added as a radical polymerization initiator and the mixture was allowed to react for 3.5 hours. Thereafter, 0.018 g of dinitrobenzene was added to stop the reaction, and 200 g of methanol was added, followed by distilling off the remaining vinyl acetate and solvent with an evaporator. This process was repeated three times to obtain an unmodified vinyl ester. Next, the unmodified vinyl ester block copolymer was saponified with sodium hydroxide, washed with methanol, and then dried in a hot air dryer at 100°C for 8 hours to obtain the desired unmodified PVA (P-3). The unmodified PVA (P-3) obtained had a number average molecular weight (Mn) of 11,300, a weight average molecular weight (Mw) of 27,000, and a degree of saponification of 99.7 mol %.

[0062] <Comparative Example 2> [Preparation of random copolymers] 400 g of vinyl acetate, 230 g of methanol, and 62 g of 1-octadecene were placed in a flask equipped with a stirring blade, and after confirming that the temperature was raised and refluxing, 0.46 g of azobisisobutyronitrile was added as a radical polymerization initiator and the mixture was allowed to react for 6 hours. Thereafter, 0.092 g of dinitrobenzene was added to stop the reaction, and 500 g of methanol was added, followed by distilling off the remaining vinyl acetate and solvent with an evaporator. This process was repeated three times to obtain a vinyl ester random copolymer. Next, the vinyl ester random copolymer was saponified with sodium hydroxide, washed with methanol, and then dried in a hot air dryer at 100°C for 8 hours to obtain the desired vinyl alcohol random copolymer (P-4). The obtained vinyl alcohol random copolymer (P-4) had a number average molecular weight (Mn) of 47,000, a weight average molecular weight (Mw) of 108,000, and a degree of saponification of 99.4 mol %.

[0063] <Comparative Example 3> Polymerization was carried out in the same manner as in Comparative Example 2, except that water was added during saponification, to obtain the target vinyl alcohol random copolymer (P-5). The obtained vinyl alcohol random copolymer (P-5) had a number average molecular weight (Mn) of 60,000, a weight average molecular weight (Mw) of 115,000, and a degree of saponification of 96.0 mol %.

[0064] The copolymers obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were subjected to the following various measurements and evaluations, and the results are shown in Table 1 below.

[0065] (Calculation of olefin modification rate (X)) The olefin modification rate (X) is 1 Using H-NMR (Bruker Japan, Ascend NMR 400), the modification rate of the olefin monomer unit was calculated from the comparison of the integral ratio of the peak (4.8 to 5.1 ppm) derived from the main chain methine of the vinyl ester to the peak (0.8 to 1.0 ppm) derived from the olefin.

[0066] (Calculation of the olefin modification rate (Y) in the PVA copolymer block (B)) The olefin modification rate (Y) in the PVA copolymer block (B) was calculated by the following formula using the solid content (a) of the PVA polymer block (A) and the solid content (b) of the entire PVA block copolymer. ·(Y)(mass%)=(X)(mass%)×b / (ba) The solid content (a) of the PVA polymer block (A) was calculated from the ratio of the weight of the reaction solution immediately before the addition of the olefin monomer, and the solid content (b) of the entire PVA block copolymer was calculated from the ratio of the weight of the reaction solution after drying it in a dryer at 140°C for 20 minutes to the weight before drying.

[0067] (Measurement of number average molecular weight, weight average molecular weight, and dispersity (molecular weight distribution)) The number average molecular weight (Mn), weight average molecular weight (Mw), and dispersity of the PVA-based block copolymer were measured under the following condition 1 for Example 2 and Comparative Example 1, and under the following condition 2 for Example 1, Comparative Example 2, and Comparative Example 3. [Condition 1] Equipment: Shimadzu Prominence Column: Tosoh Corporation, TSKgel α-M 13 μm, 7.8 mm I.D. x 30 cm Column temperature: 35℃ ·Eluent: 0.2M, NaNO3 aqueous solution ·Injection volume: 50μL ·Flow rate: 0.5mL / min Detector: RI (Shodex RI-501) ·Analysis time: 30min Sample preparation: Adjust the concentration to 0.1% using the eluent, and dissolve by heating at 90°C under stirring. After dissolution, filter through a 0.45 μm disc filter and analyze. Standard sample: Agilent PEO / PEG [Condition 2] ·Equipment: HLC-8420GPC EcoSEC Elite Column: HFIP-G8B HFIP-806M x2 Column temperature: 40℃ Eluent: 5mM TFA-Na HFIP ·Injection volume: 50μL ·Flow rate: S / R 0.5mL / 0.125mL Detector: RI Sample preparation: 10 mg of sample is mixed with 10 mL of eluent and gently stirred with a rotary mixer. After leaving the mixture to stand for two nights, it is filtered through a 0.45 μm PTFE filter and analyzed. Calibration curve: Monodisperse PMMA 3-order Agilent EasiVials with 1.5 mL of eluent added

[0068] (Measurement of Saponification Degree) The degree of saponification is measured as follows: 1 Using H-NMR (Bruker Japan, Ascend NMR 400), the degree of saponification was calculated from the comparison of the integral ratio of the peaks (1.05 to 1.85 ppm) derived from the main chain methylene of vinyl alcohol and vinyl ester to the peaks (1.9 to 2.05 ppm) derived from the methyl of the side chain acetyl group.

[0069] (Determination of water solubility) Water solubility was determined by adding the obtained sample to ion-exchanged water to a concentration of 4%, heating and stirring at 95°C, and evaluating it as "soluble" if it completely dissolved within 4 hours, or as "insoluble" if it did not dissolve.

[0070] (Water contact angle measurement) A 4% aqueous solution was prepared using the obtained sample, which was then cast onto a PET film and dried at 25°C for one week to obtain a film with a thickness of 100 µm. After conditioning the film at 25°C and 55% RH for one week, a drop of water was dropped onto the film surface using a Kyowa Interface Science "DropMaster DM-500" to measure the contact angle of the drop. The contact angle was automatically measured using analysis software FAMAS on an image taken two seconds after the drop was dropped. Each sample was measured 10 times, and the average of the eight points excluding the maximum and minimum values ​​was calculated.

[0071] [Table 1]

[0072] From the results in Table 1 above, Examples 1 and 2, in which an olefin was introduced as a vinyl alcohol-based block copolymer, were water-soluble, whereas Comparative Examples 2 and 3, in which an olefin was introduced as a vinyl alcohol-based random copolymer, were insoluble in water and had poor water solubility. Furthermore, the unmodified PVA of Comparative Example 1 is water-soluble, but has a smaller water contact angle than those of Examples 1 and 2, indicating that it has a low affinity with hydrophobic materials.

[0073] <Examples 3 and 4, Comparative Examples 4 and 5> The copolymer powders of Examples 1 and 2 and Comparative Examples 2 and 3 and high-density polyethylene resin (HDPE) (Novatec HJ-360, manufactured by Japan Polyethylene Co., Ltd.) were mixed in the ratios shown in Table 2. The blends were fed into a benchtop kneader (Xplore MC15HT, manufactured by DSM) and melt-kneaded at a cylinder temperature of 240°C and a screw rotation speed of 100 rpm to obtain pellets of each thermoplastic resin composition. The blending ratio of each pellet and the analysis results are shown in Table 2 below.

[0074] The following various measurements and evaluations were carried out on the thermoplastic resin composition pellets obtained in Examples 3 and 4 and Comparative Examples 4 and 5. The results are shown in Table 2 below.

[0075] (Determination of dispersibility) High-density polyethylene and PVA-based block copolymer were kneaded, and the resulting pellets were surfaced using a microtome. They were then etched in an ultrasonic cleaner at 60°C for 2 hours and vacuum dried at 40°C. When observed under a scanning electron microscope (SEM), the particle sizes of the PVA-based block copolymer dispersed in the high-density polyethylene were evaluated as follows: if all particles were 2 μm or less, they were evaluated as ◎; if they were 5 μm or less, they were evaluated as ○; and if at least one particle was 5 μm or more, they were evaluated as ×.

[0076] (Measurement of breaking elongation) High-density polyethylene and PVA-based block copolymer were mixed and kneaded, and the resulting pellets were molded into a 0.5 mm thick film using a press molding machine. Samples were cut out to 15 mm x 60 mm and subjected to a tensile test using a tensile tester (Shimadzu Corporation, Autograph AG-IS) at a chuck distance of 20 mm and a pulling speed of 200 mm / min to determine the elongation at the point where the film broke. Each sample was measured three times, and the average value was calculated.

[0077] [Table 2]

[0078] From the results in Table 2 above, Examples 3 and 4 had good dispersibility and higher elongation at break than Comparative Examples 4 and 5. This shows that polymers into which olefins are introduced as block copolymers have better affinity with hydrophobic polymers than polymers into which olefins are introduced as random copolymers. [Industrial Applicability]

[0079] The vinyl alcohol-based block copolymer of the present invention has high water solubility, yet when formed into a coating, its surface exhibits hydrophobicity, has excellent affinity with hydrophobic materials, and exhibits high affinity when alloyed with hydrophobic materials. Therefore, it is highly expected to be used in various fields such as medical and industrial fields.

Claims

1. A vinyl alcohol-based block copolymer having a vinyl alcohol-based polymer block (A) and a vinyl alcohol-based copolymer block (B) containing a vinyl alcohol-based monomer unit and an olefin-based monomer unit having a long-chain alkyl group having 5 to 20 carbon atoms.

2. 2. The vinyl alcohol-based block copolymer according to claim 1, wherein the content of the olefin-based monomer units having a long-chain alkyl group having 5 to 20 carbon atoms is 0.1 to 20 mol % based on the total monomer units of the vinyl alcohol-based block copolymer.

3. 3. The vinyl alcohol-based block copolymer according to claim 1, wherein the number average molecular weight of the vinyl alcohol-based block copolymer is 1,000 to 250,000.

4. 3. The vinyl alcohol block copolymer according to claim 1, wherein the degree of saponification of the vinyl alcohol block copolymer is 60 to 100 mol %.

5. A resin composition comprising at least a polyolefin resin and the vinyl alcohol block copolymer according to claim 1 or 2.

6. A permeation membrane comprising the resin composition according to claim 5.

7. a step of polymerizing a vinyl ester-based monomer in the presence of a radical initiator and an organic cobalt complex to obtain a vinyl ester-based polymer block (A-1); a step of polymerizing an olefin-based monomer having a long-chain alkyl group having 5 to 20 carbon atoms and a vinyl ester-based monomer in the presence of a radical initiator and an organic cobalt complex to obtain a vinyl ester-based copolymer block (B-1); The method for producing a vinyl alcohol-based block copolymer includes a step of saponifying the obtained vinyl ester-based polymer block (A-1) and vinyl ester-based copolymer block (B-1) to obtain a vinyl alcohol-based block copolymer.

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