TW201518374A - Vinyl acetal-type polymer - Google Patents

Abstract

The purpose of the present invention is to provide a vinyl acetal-type polymer of which the viscosity can be reduced while keeping mechanical properties such as strength. The purpose can be achieved by providing a vinyl acetal-type polymer produced by acetalizing a vinyl alcohol-containing copolymer that is produced by saponifying a copolymer of vinyl acetate and a polyfunctional monomer, wherein the polyfunctional monomer has at last two ethylenical double bonds in the molecule, the vinyl alcohol-containing copolymer has an ethylenical double bond in a side chain, the molar ratio (d) of the ethylenical double bond relative to the total amount of a vinyl alcohol unit and a vinyl acetate unit is 0.05/100 to 2/100, and the degree of acetalization is 45 to 80 mol%.

Description

Ethylene acetal polymer

The present invention relates to an ethylene acetal polymer obtained by acetalizing a water-soluble vinyl alcohol-based copolymer obtained by saponifying a copolymer of vinyl acetate and a polyfunctional monomer.

In order to improve the workability in melting or dissolving the ethylene acetal polymer, a method of lowering the degree of polymerization of the vinyl alcohol-based copolymer of the raw material is generally used as a method for lowering the viscosity of the ethylene acetal polymer. However, as the degree of polymerization of the vinyl alcohol-based copolymer is lowered, the mechanical properties such as the strength of the ethylene acetal polymer are lowered. Therefore, the use of such a low degree of polymerization of an ethylene acetal polymer can be limited to a part of the use.

In order to improve the mechanical properties and other physical properties such as the strength of the ethylene acetal polymer, it is proposed to introduce a double bond into the molecule of the ethylene acetal polymer to carry out crosslinking. The molecule of the ethylene acetal polymer is disclosed, for example, by reacting a compound having a functional group reactive with a hydroxyl group such as an isocyanate group or a glycidyl group in the molecule with an ethylenic double bond and a residual hydroxyl group of the polyvinyl acetal. The double bond is introduced into the crosslink (for example, Patent Documents 1 and 2). In particular, in Patent Document 2, it is described by making points The specific compound having an epoxy group and an ethylenic double bond reacts with the polyvinyl acetal, and the molecular weight of the polyvinyl acetal hardly changes, and the viscosity can be low.

Further, in another method of introducing a double bond into a molecule of an ethylene acetal polymer to crosslink, a compound having a functional group having an aldehyde group or an acetal group in the molecule and an ethylenic double bond, and a polyethylene are disclosed. The acetal is subjected to an acetalization reaction to introduce a double bond into the molecule of the ethylene acetal polymer (for example, Patent Document 3 is incorporated by reference). In Patent Document 3, the composition for a crosslinked ceramic green sheet containing an ethylene acetal-based polymer obtained is excellent in viscosity and workability in the same manner as a normal polyethylene acetal, and the obtained sheet is crosslinked to have high strength. Chemical.

However, in the methods described in Patent Documents 1 to 3, it cannot be said that the mechanical properties such as strength are maintained, and the viscosity is sufficiently low, and in order to introduce an ethylenic double bond into the molecule of the polyvinyl acetal, there is a general aggregation. Compared with the method for producing ethylene acetal, the reaction step is increased, and the production cost is greatly increased.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] JP-A-2007-115827

[Patent Document 2] Japanese Patent Publication No. 2009-520856

[Patent Document 3] JP-A-2009-108305

Therefore, an ethylene acetal-based polymer which maintains mechanical properties such as strength and which has low viscosity can be obtained.

The above-mentioned problem is an ethylene acetal polymer obtained by acetalizing a vinyl alcohol-based copolymer obtained by saponifying a copolymer of vinyl acetate and a polyfunctional monomer; the polyfunctional monomer is contained in a molecule. Two or more ethylenic double bonds, wherein the vinyl alcohol-based copolymer has a molar ratio of the ethylenic double bond in the side chain and a total of the vinyl double bond relative to the total of the vinyl alcohol unit and the vinyl acetate unit ( d) It is solved by an ethylene acetal polymer having a acetalization degree of from 0.05 to 100 to 2/100 and a degree of acetalization of from 45 to 80 mol%.

In this case, it is preferred that the side chain contains a vinyl ether group. It is also preferred that the aforementioned side chain contains an allyl group.

According to the present invention, an ethylene acetal polymer having a side chain to introduce an ethylenic double bond can be provided. The ethylene acetal polymer of the present invention is excellent in solubility in an alcohol-based solvent or the like, and has low solution viscosity and melt viscosity, and is excellent in handleability. Further, the mechanical properties such as strength are maintained while the viscosity is low. Therefore, the ethylene acetal polymer is suitable for use in the interlayer film composition for cemented glass, ceramic paste composition, ink composition. Various uses such as a coating composition, an adhesive composition, and a thermally developed photosensitive material composition.

[Fig. 1] ¹ H-NMR spectrum of polyvinyl acetate obtained in Example 1.

Fig. 2 is a ¹ H-NMR spectrum of the vinyl alcohol-based copolymer obtained in Example 1.

[Best Practice for Carrying Out the Invention]

The present invention relates to an ethylene acetal polymer obtained by acetalizing a vinyl alcohol-based copolymer obtained by saponifying a copolymer of vinyl acetate and a polyfunctional monomer. The vinyl alcohol-based copolymer is acetalized to obtain an ethylene acetal-based polymer, and the vinyl alcohol-based copolymer is preferably water-soluble. Therefore, the ethylene acetal-based polymer of the present invention is preferably obtained by acetalization of a vinyl alcohol-based copolymer having a water-soluble vinyl double bond in its side chain.

When a polyfunctional monomer having two or more ethylenic double bonds in a molecule is polymerized together with vinyl acetate, a plurality of ethylene double bond reactions in the polyfunctional monomer cannot be avoided. On the other hand, in this case, since the polyfunctional monomer unit becomes a crosslinking point, the obtained polymer is crosslinked and is insoluble to the solvent. However, as a result of review by the present inventors, a water-soluble vinyl alcohol-based copolymer can be obtained by containing a necessary amount of an ethylenic double bond while suppressing crosslinking. Hereinafter, the vinyl alcohol-based copolymer will be described in detail.

The polyfunctional monomer used in the present invention is not particularly limited as long as it contains two or more ethylenic double bonds in the molecule. But not because of excessive cross-linking It is preferred that the reaction proceeds to inhibit the water solubility of the vinyl alcohol-based copolymer and to introduce a necessary amount of a double bond. The mixing ratio of the polyfunctional monomer of vinyl acetate depends on various factors such as polymerization temperature, monomer concentration, polymerization rate, and polymerization degree, and it is necessary to select a polyfunctional monomer having appropriate reactivity. From the viewpoint of suppressing the excessive crosslinking reaction, the number of the ethylenic double bonds contained in the polyfunctional monomer is preferably two. The polyfunctional monomer exemplified below may be used alone or in combination of two or more.

Among them, the polyfunctional monomer may, for example, be ethanediol divinyl ether, propane diol divinyl ether or butane diol divinyl ether (for example, 1,4-butanediol divinyl ether). , ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, polypropylene glycol divinyl ether, four A vinyl ether group-containing monomer such as a divinyl ether compound such as ethylene glycol divinyl ether is preferred. A monomer containing a vinyl ether group, particularly, 1,4-butanediol divinyl ether or triethylene glycol divinyl ether, can easily control the degree of polymerization or the content of a double bond of the vinyl alcohol-based copolymer. More suitable to use.

Further, an allyl group-containing monomer is also preferred. Examples of the allyl group-containing monomer include diene compounds such as pentadiene, hexadiene, heptadiene, octadiene, decadiene, and decadiene (for example, 1,9-decadiene). , glycerol diallyl ether, diethylene glycol diallyl ether, ethylene glycol diallyl ether, triethylene glycol diallyl ether, polyethylene glycol diallyl ether, trishydroxyl a diallyl ether compound such as a propane diallyl ether or a pentaerythritol diallyl ether, a glyceryl triallyl ether, a trimethylolpropane triallyl ether, or a pentaerythritol triallyl ether Allyl ether compound, pentaerythritol tetraallyl a monomer containing an allyl ether group like a tetraallyl ether compound such as ether; diallyl phthalate, diallyl maleate, diallyl itaconate, p-phenylene a diallyl-like allyl ester-containing monomer such as diallylcarboxylate or diallyl adipate; a diene such as diallylamine or diallylmethylamine; a monomer containing an allylamino group such as a propylamine compound or triallylamine; or a monomer having an allyl ammonium group such as a diallyl ammonium salt such as diallyldimethylammonium chloride; Isoallyl cyanuric acid; 1,3-diallyl urea; triallyl phosphate; diallyl disulfide. The allyl ether group-containing monomer, in particular, 1,9-decadiene, polyethylene glycol diallyl ether, pentaerythritol diallyl ether, can easily control the degree of polymerization or double bond of the vinyl alcohol copolymer The content is more suitable for use.

Further, in addition to the above polyfunctional monomer, for example, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene II may be mentioned. Alcohol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, glycerol di(meth)acrylate, glycerol tris(meth)acrylate, pentaerythritol tris(a) Acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate a monomer having (meth)acrylic acid such as tris (meth) acrylate or the like; N,N'-methylenebis(meth)acrylamide, N,N'-ethylene bis ( A monomer having (meth) acrylamide, such as methyl acrylamide, divinylbenzene or trivinylbenzene.

The vinyl alcohol copolymer used in the present invention is made by making B The vinyl ester is copolymerized with a polyfunctional monomer to obtain a vinyl ester copolymer, and then the vinyl ester copolymer is saponified to produce. According to this production method, a vinyl alcohol-based copolymer in which a component derived from a polyfunctional monomer is uniformly distributed in a molecular chain can be obtained.

In the above production method, it is preferred that the molar ratio (p) of the above polyfunctional monomer to vinyl acetate is 0.1/100 to 5/100. When the molar ratio (p) is less than 0.1/100, it becomes difficult to introduce a vinyl double bond into the side chain. The molar ratio (p) is preferably 0.15/100 or more, more preferably 0.2/100 or more. On the other hand, when the molar ratio (p) exceeds 5/100, it is difficult to control the degree of polymerization of the vinyl ester-based copolymer. Further, the vinyl alcohol-based copolymer obtained by saponifying the vinyl ester-based copolymer is insoluble in water. The molar ratio (p) is preferably 3/100 or less, and more preferably 2/100 or less.

As the polymerization method of the vinyl acetate and the polyfunctional monomer, any polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method can be employed. Further, the copolymerization can be carried out in the absence of a solvent or an alcohol-based solvent. Among them, a solution polymerization method using a solvent-free bulk polymerization method and an alcohol-based solvent is preferably used. The alcohol-based solvent is not particularly limited, and for example, methanol, ethanol, propanol or the like may be used singly or in combination of two or more kinds. The manner of copolymerization is not particularly limited, and batch polymerization, semi-batch polymerization, continuous polymerization, and semi-continuous polymerization may be used.

The temperature (copolymerization temperature) at the time of copolymerizing vinyl acetate and a polyfunctional monomer is not specifically limited. The copolymerization temperature is preferably 0 to 200 ° C, more preferably 30 to 140 ° C. When the copolymerization temperature is lower than 0 ° C, a sufficient polymerization rate may not be obtained. a field with a higher copolymerization temperature than 200 ° C In combination, there is a decomposition of vinyl acetate or a polyfunctional monomer used.

The method of controlling the copolymerization temperature is not particularly limited. In the method of controlling the copolymerization temperature, for example, a method of obtaining a balance between the heat generated by the polymerization and the heat release on the surface of the polymerization vessel can be obtained by controlling the polymerization rate. Further, for example, a method of controlling the outer layer by using a suitable heat medium may be mentioned. From the perspective of safety, the latter method is preferred.

A polymerization initiator used in copolymerizing vinyl acetate with a polyfunctional monomer, starting from a conventional initiator (for example, an azo initiator, a peroxide initiator, a redox system) in accordance with a polymerization method Agent, etc.) can be selected. In terms of azo initiators, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis ( 4-methoxy-2,4-dimethylvaleronitrile) and the like. In the case of a peroxide-based initiator, for example, a percarbonate compound such as diisopropylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate or diethoxyethylperoxydicarbonate a perester compound such as t-butyl peroxy neodecanoate, α-cumyl peroxy neodecanoate or t-butyl peroxyphthalate; acetamidine cyclohexylsulfonyl peroxide 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate and the like. These initiators may also be combined with potassium persulfate, ammonium persulfate, hydrogen peroxide or the like as a starter. Examples of the redox-based initiator include a combination of the above-mentioned peroxide and a reducing agent such as sodium hydrogen sulfite, sodium hydrogencarbonate, tartaric acid, L-ascorbic acid, and Rongalit. In the case where the copolymerization is carried out at a high temperature, there is a case where the coloration due to decomposition of vinyl acetate is observed. In this case, for the purpose of preventing coloration, a tartaric acid-like antioxidant may be added to the polymerization system in an amount of about 1 to 100 ppm with respect to vinyl acetate.

When the vinyl acetate is copolymerized with a polyfunctional monomer, other monomers may be copolymerized without impairing the scope of the present invention. As such other monomers, for example, α-olefins such as ethylene and propylene; (meth)acrylic acid and salts thereof; methyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylic acid n -propyl ester, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, ( (meth) acrylates such as 2-ethylhexyl methacrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate; (meth) acrylamide; N -Methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, diacetone (meth) acrylamide, (A Acrylamide sulfonic acid and its salt, (meth) acrylamidopropyl dimethylamine and its salt or its grade 4 salt, N-methylol (meth) acrylamide and its derivatives (meth) acrylamide derivatives; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i- Butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, etc. Alkenyl ethers; nitriles such as acrylonitrile and methacrylonitrile; halogenated vinyl esters such as vinyl chloride and vinyl fluoride; vinyl chloride and vinyl fluoride Halogenated vinylidene esters; allyl acetate compounds such as allyl acetate and allyl chloride; unsaturated dicarboxylic acids such as maleic acid, itaconic acid and fumaric acid a salt or an ester thereof; a vinyl decyl ester compound such as vinyl trimethoxy decane; isopropenyl acetate or the like. The copolymerization amount of such other monomers is usually 5 mol% or less.

The copolymerization of the vinyl acetate and the polyfunctional monomer for the purpose of adjusting the degree of polymerization of the obtained copolymer and the like can be carried out in the presence of a chain transfer agent without impairing the gist of the present invention. Examples of the chain transfer agent include aldehydes such as acetaldehyde and propionaldehyde; ketones such as acetone and methyl ethyl ketone; mercaptans such as 2-hydroxyethanethiol; trichloroethylene and perchloroethylene; Halogenated hydrocarbons, etc. Among them, aldehydes and ketones are preferably used. The amount of the chain transfer agent to be added may be determined depending on the chain transfer constant of the chain transfer agent to be added and the degree of polymerization of the desired vinyl alcohol-based copolymer, but it is preferably about 0.1 to 10% by mass based on the vinyl acetate.

Further, the polymerization rate of vinyl acetate is preferably from 20 to 90%. When the polymerization rate of vinyl acetate is less than 20%, the amount of the vinyl ester-based copolymer which can be produced per unit time is reduced, and the production efficiency is lowered, and the cost of recovering vinyl acetate is increased. From the viewpoint of production efficiency and cost, the polymerization rate of vinyl acetate is preferably 30% or more, more preferably 40% or more. On the other hand, when the polymerization rate of vinyl acetate exceeds 90%, the crosslinking reaction proceeds excessively, and the water solubility of the obtained vinyl alcohol-based copolymer is lowered. From the viewpoint of suppression of the crosslinking reaction, the polymerization rate of vinyl acetate is preferably 80% or less, more preferably 70% or less. Further, the polymerization rate was measured by subjecting the obtained polymer solution to vacuum drying at 120 ° C for 2 hours to calculate a solid content of the polymer.

The saponification method of the vinyl ester-based copolymer obtained by copolymerizing vinyl acetate and a polyfunctional monomer is not particularly limited, and a conventional saponification method can be employed. For example, an alkaline catalyst such as sodium hydroxide, potassium hydroxide or sodium methoxide or an alcoholic catalyst such as p-toluenesulfonic acid is used for the alcoholysis reaction or hydrolysis reaction. should. Examples of the solvent which can be used for the reaction include alcohols such as methanol and ethanol; esters such as methyl acetate and ethyl acetate; and ketones such as acetone methyl ethyl ketone: aromatic hydrocarbons such as benzene and toluene. Wait. These solvents may be used singly or in combination of two or more kinds. Among them, a methanol or methanol/acetic acid methyl ester mixed solution is used as a solvent, and sodium hydroxide is used as a catalyst for saponification.

The degree of saponification of the vinyl alcohol-based copolymer used in the present invention is preferably from 60 to 99.9 mol%. When the degree of saponification is less than 60 mol%, there is a case where the vinyl alcohol-based copolymer becomes insoluble in water. The degree of saponification is preferably 65 mol% or more. On the other hand, when the degree of saponification is more than 99.9 mol%, it is difficult to industrially manufacture, and the viscosity stability of the aqueous solution of the vinyl alcohol-based copolymer is deteriorated, and handling is difficult. The degree of saponification is preferably 98 mol% or less.

Further, the degree of saponification is a value measured in accordance with the method for measuring the degree of saponification described in JIS K6726. In this case, the unit other than the monomer unit including the vinyl alcohol unit, the vinyl acetate unit, and the ethylenic double bond is a small amount even if it is contained in the vinyl alcohol-based copolymer, so that the unit can be saponified regardless of such units. Degree calculation.

The vinyl alcohol-based copolymer used in the present invention preferably has a viscosity average degree of polymerization Pη of from 100 to 8,000. If the viscosity average degree of polymerization Pη is less than 100, industrial production becomes difficult. The viscosity average degree of polymerization Pη is more preferably 200 or more. On the other hand, when the viscosity average degree of polymerization Pη exceeds 8,000, industrial production is difficult, and the viscosity of the vinyl alcohol-based copolymer aqueous solution is extremely high and the operation is difficult. Viscosity average degree of polymerization Pη is preferably 5,000 or less, more preferably 2,500 or less.

The viscosity average degree of polymerization Pη is measured in accordance with JIS K6726. Specifically, after the vinyl alcohol-based copolymer is further saponified, the remaining acetate group is completely saponified. After re-saponifying the vinyl alcohol-based copolymer was purified and dried, 1 g of the dried sample was added to 100 ml of water, dissolved by heating, and cooled to 30 °C. The obtained aqueous solution was measured by viscosity, and the ultimate viscosity [η] (unit: L/g) in water at 30 ° C was measured, and the measured ultimate viscosity [η] was calculated by the following formula (1).

[Number 1] Viscosity average degree of polymerization P η = ([ η ] × 10000 / 8.29) ^(1/0.62) (1)

The ratio Mw/Mn of the weight average molecular weight Mw and the number average molecular weight Mn determined by the size exclusion chromatography of the vinyl alcohol-based copolymer used in the present invention is preferably 2 to 5, more preferably 2 to 4. If the Mw/Mn is less than 2, it will be difficult to produce in industry. Moreover, when Mw/Mn exceeds 5, when an ethylene acetal type polymer is produced, the acetalization reaction rate tends to fall.

The vinyl alcohol-based copolymer used in the present invention preferably has water solubility and contains an ethylenic double bond in its side chain. Further, the molar ratio (d) of the ethylenic double bond to the total of the vinyl alcohol unit and the vinyl acetate unit is 0.05/100 to 2/100. When the molar ratio (d) is less than 0.05/100, the mechanical properties such as the strength of the obtained ethylene acetal polymer are insufficient. The molar ratio (d) is preferably 0.07/100 or more, more preferably 0.1/100 or more. On the other hand, when the molar ratio (d) exceeds 2/100, the control of the degree of polymerization of the vinyl ester-based copolymer becomes extremely difficult, and the obtained vinyl alcohol-based copolymer becomes not It is easy to dissolve in water and acetalization. The molar ratio (d) of the ethylenic double bond is preferably 1.5/100 or less, more preferably 1/100 or less.

The vinyl alcohol-based copolymer used in the present invention preferably contains a vinyl ether group in its side chain. Further, it is also preferred that the side chain contains an allyl group or an allyl ether group. Since these structures have a moderate reactivity with respect to the vinyl ester group contained in the vinyl acetate, the ratio of the monomer which reacts only one of the double bonds can be increased while suppressing the crosslinking reaction. By this, a water-soluble vinyl alcohol-based copolymer in which the content of the double bond is controlled can be obtained. Further, since the vinyl alcohol-based copolymer having such a side chain has a necessary amount of double bonds and water solubility, it is preferable to make the ethylene acetal polymer industrially economical and economically stable.

Ethylenic double bond introduced by the amount of heavy water or heavy dimethyl vinyl alcohol copolymer in a solvent of ¹ H-NMR spectrum sulfoxide, or a vinyl ester copolymer before saponification of the heavy chloroform solvent in the ¹ H - NMR spectrometry. The introduction amount of the ethylenic double bond is controlled by the mixing ratio or polymerization ratio of the vinyl ester monomer of the polyfunctional monomer.

The control of the crosslinking reaction is carried out by introducing a necessary amount of a double bond to the vinyl alcohol-based copolymer, and the production efficiency is also maintained from the viewpoint of the molar double bond of the vinyl alcohol unit and the vinyl acetate unit. The ratio (d/p) of the molar ratio (d) of the polyfunctional monomer of (d) to the vinyl acetate is preferably 0.2 or more, more preferably 0.5 or more. When the ratio (d/p) is less than 0.2, the ratio of the product of crosslinking of the vinyl acetate to the polyfunctional monomer increases, and the water solubility of the vinyl alcohol-based copolymer is inhibited. Although it can be made by the mixing ratio or polymerization conditions of the polyfunctional monomer relative to vinyl acetate The ratio (d/p) is increased, but the production efficiency is considered, and the ratio (d/p) is preferably 0.8 or less.

In the present specification, when the vinyl alcohol-based copolymer is water-soluble, an aqueous solution of a vinyl alcohol-based copolymer having a temperature of 40° C. at a temperature of 90° C. is used, and the vinyl alcohol-based copolymer is completely dissolved in water.

The ethylene acetal-based polymer of the present invention is obtained by acetalizing a vinyl alcohol-based copolymer obtained as described above by a conventional method. The degree of acetalization at this time is 45 mol% or more and 80 mol% or less. When the degree of acetalization is in this range, the ethylene acetal polymer can form a film which is excellent in softness and water resistance, and can improve the solubility of a solvent having a wide range of polarities such as an alcohol-based solvent. The degree of acetalization of the ethylene acetal polymer is preferably 55 mol% or more, more preferably 60 mol%. Further, the degree of acetalization of the ethylene acetal polymer can be appropriately selected depending on the solubility of the solvent to be used. The degree of acetalization of the ethylene acetal polymer can be adjusted, and the amount of the aldehyde added to the vinyl alcohol-based copolymer to be used, the reaction time after the addition of the aldehyde and the acid catalyst, and the like can be appropriately adjusted.

Here, the degree of acetalization of the ethylene acetal polymer is a ratio of the acetalized vinyl alcohol unit to the all monomer unit constituting the ethylene acetal polymer. The degree of acetalization can be measured, for example, according to the method of JIS K6728 (1977).

In the method of acetalizing a vinyl alcohol-based copolymer, for example, (1) a vinyl alcohol-based copolymer is heated and dissolved in water to prepare an aqueous solution having a concentration of 5 to 30% by mass, and is cooled to 5 to 50 ° C. After that, add a specific amount of aldehyde, cool to -10 ° C ~ 30 ° C, add acid to make the pH of the aqueous solution 1 or less, a method of starting acetalization, (2) heating and dissolving a vinyl alcohol-based copolymer in water, preparing an aqueous solution having a concentration of 5 to 30% by mass, cooling it to 5 to 50 ° C, and adding an acid to an aqueous solution After the pH is 1 or less, it is cooled to -10 ° C to 30 ° C, and a method of initiating acetalization after adding a specific amount of aldehyde is carried out.

For aldehydes used in acetalization, such as formaldehyde (including paraformaldehyde), acetaldehyde (including paraldehyde), propionaldehyde, butyl aldehyde, isobutyl aldehyde, 2-ethyl butyl aldehyde, valeraldehyde, An aliphatic aldehyde such as neopentanal, pentyl aldehyde, hexyl aldehyde, heptyl aldehyde, 2-ethylhexyl aldehyde, octyl aldehyde, mercapto aldehyde, mercapto aldehyde, dodecyl aldehyde, etc.; cyclopentanal, A An alicyclic aldehyde such as a cyclopentanal, a dimethylcyclopentanal, a cyclohexane aldehyde, a methylcyclohexane aldehyde, a dimethylcyclohexane aldehyde or a cyclohexane acetaldehyde; a cyclopentenal a cyclounsaturated aldehyde such as cyclohexenal; benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, dimethylbenzaldehyde, methoxy Aromatic or benzoylaldehyde, phenylacetaldehyde, β-phenylpropanal, cumyl aldehyde, naphthyl aldehyde, furfural, cinnamaldehyde, crotonaldehyde, acrolein, 7-octene-1- aldehyde, etc. An unsaturated aldehyde containing an unsaturated bond; a heterocyclic aldehyde such as furfural or methylfuraldehyde or the like.

Among these, at least one selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, butyl aldehyde, hexyl aldehyde, and benzaldehyde is preferred, and butyl aldehyde is particularly preferred. By using such an aldehyde, the acetalization of the vinyl alcohol-based copolymer can be more efficiently carried out.

Further, as the aldehyde used for the acetalization, an aldehyde having a functional group such as a hydroxyl group, a carboxyl group, a sulfonic acid group or a phosphoric acid group can be used without impairing the effect of the present invention.

The acid to be used for acetalization is not particularly limited, and examples thereof include acetic acid, p-toluenesulfonic acid, nitric acid, sulfuric acid, and hydrochloric acid. Among these, hydrochloric acid, sulfuric acid, and nitric acid are preferred, and hydrochloric acid and nitric acid are more preferable. These may be used in combination of two or more kinds. Further, the time required for the acetalization reaction is usually about 1 hour to 10 hours, and the reaction is preferably carried out under stirring. Further, when the acetal is carried out under the above temperature conditions and the degree of acetalization of the ethylene acetal polymer does not rise, the reaction can be continued at a temperature of about 50 ° C to 80 ° C.

After the acetalization, the obtained particulate reaction product is filtered, and the mixture is sufficiently washed with water, and a neutralizing agent such as a base is added thereto, followed by washing and drying to obtain a desired ethylene acetal polymer. Examples of the base compound which can be used as a neutralizing agent include sodium hydroxide, potassium hydroxide and the like.

The ethylene acetal polymer of the present invention is an acetalized product of a copolymer of a polyfunctional compound having two or more ethylenic double bonds in the molecule and a vinyl alcohol, and the side chain has an amount of an ethylenic double bond relative to the vinyl group. The alcohol unit and its derivative are 0.05 to 2 mol%, and the degree of acetalization is 45 to 80 mol%. Here, the derivative unit of the vinyl alcohol unit means an acetal unit obtained by acetalization of a vinyl acetate unit or a vinyl alcohol unit which is not saponified in the production step of the vinyl alcohol-based copolymer. The amount of the ethylenic double bond is preferably 0.07 mol% or more, more preferably 0.1 mol% or more. When the amount of the ethylenic double bond is less than 0.05 mol%, mechanical properties such as sufficient strength cannot be obtained. Further, it is preferably 1.5 mol% or less, more preferably 1 mol% or less. When the amount of the ethylenic double bond exceeds 2 mol%, the vinyl alcohol-based copolymer used in the production of the ethylene acetal polymer is easily dissolved in water and is difficult to produce. The amount of the above-mentioned ethylenic double bond is ¹ H-NMR spectrum in a heavy dimethyl hydrazine solvent of an ethylene acetal polymer, heavy water of a vinyl alcohol-based copolymer before acetalization, or heavy dimethylene ¹ H-NMR spectrum measured in heavy chloroform solvent in the solvent sulfone ¹ H-NMR spectrum, vinyl ester copolymer, or the front of the saponification. The amount of the ethylenic double bond measured in each step of the ethylene acetal polymer, the vinyl alcohol polymer, and the vinyl ester polymer was basically the same.

The ethylene acetal polymer of the present invention produced as described above is excellent in solubility in an alcohol-based solvent or the like, and the solution viscosity is controlled to be low in viscosity and excellent in workability. Therefore, the ethylene acetal polymer of the present invention is suitable for use in an interlayer film composition for cemented glass, a slurry composition for ceramics, and an ink composition. Various uses such as a coating composition, an adhesive composition, and a thermally developed photosensitive material composition.

[Examples]

Hereinafter, the present invention will be described in detail by way of examples. In the following examples and comparative examples, the parts and % are each in parts by mass and mass% unless otherwise specified.

<Evaluation of vinyl alcohol copolymers>

The vinyl alcohol-based copolymer obtained in each of the examples and the comparative examples was evaluated by the following method.

(Measurement of the amount of introduction of ethylene double bonds)

0.3 mg of the vinyl alcohol-based copolymer was dissolved in 3 ml of dimethyl hydrazine, and a ¹ H-NMR measurement was carried out using a nuclear magnetic resonance device (manufactured by JEOL Ltd., LAMBDA500). From the obtained spectrum, the amount of introduction of the ethylenic double bond (mol ratio (d)) to the total of the vinyl alcohol unit and the vinyl acetate unit was calculated.

(Measurement of viscosity average degree of polymerization)

The viscosity average degree of polymerization Pη of the vinyl alcohol-based copolymer was measured in accordance with JIS K6726. Specifically, the residual acetic acid group is completely saponified by re-saponifying the vinyl alcohol-based copolymer. After the resaponified vinyl alcohol-based copolymer was purified and dried, 1 g of the dried sample was added to 100 ml of water, dissolved by heating, and cooled to 30 °C. The obtained aqueous solution was measured by viscosity, and the ultimate viscosity [η] (unit: L/g) in water at 30 ° C was measured. The viscosity average degree of polymerization Pη is calculated from the measured ultimate viscosity [η] by the following formula (2).

[Number 2] Viscosity average degree of polymerization P η = ([ η ] × 10000 / 8.29) ^(1/0.62) (2)

(Measurement of saponification degree)

The vinyl alcohol-based copolymer was measured by a method for measuring the degree of saponification described in JIS K6726.

<Evaluation of ethylene acetal polymer>

The ethylene acetal polymer obtained in each of the examples and the comparative examples was evaluated by the following method.

(Measurement of acetalization degree)

The degree of acetalization of the ethylene acetal polymer was analyzed in accordance with the method described in JIS K6728.

(Evaluation of Solubility and Determination of Solution Viscosity)

With respect to the ethylene acetal polymer, a 5 mass% ethanol/water (95 mass%/5 mass%) solution was prepared, and the solubility of each ethylene acetal polymer was visually observed. Those who are completely dissolved are evaluated as "○", and those who are completely insoluble are evaluated as "X". The results are shown in Table 2. Further, when the ethylene acetal polymer was completely dissolved, the obtained solution was allowed to stand in a thermostat at 20 ° C for 2 hours or more, and the viscosity (mPa.s) of the solution was measured using a rotary viscometer type viscometer.

(Evaluation of mechanical properties)

The ethylene acetal-based polymer obtained in each of the following Examples and Comparative Examples was subjected to a casting method using a 10% by mass solution of ethanol/water (95% by mass / 5% by mass) at 50 ° C. After drying in an hour, a film having a thickness of 100 μm was produced. The tensile test was carried out in accordance with JIS K7162. More specifically, a film having a thickness of 100 μm was cut into a dumbbell shape, and a tensile tester (manufactured by Shimadzu Corporation, a universal material testing machine AG-IS) was used, and the tensile test was performed at a tensile speed of 50 mm/min. The maximum tensile stress applied during the test. For each of the examples and the comparative examples, five test pieces were prepared, and the maximum tensile stress was measured, and the average value was used as the tensile strength.

[Example 1] (Synthesis of vinyl alcohol copolymer PVA-1 having a side chain having an ethylenic double bond)

In a 6 L reaction tank equipped with a stirrer, a nitrogen inlet, an additive inlet, and an initiator addition port, 1200 g of vinyl acetate, 1800 g of methanol, and 1,4-butanediol divinyl as a polyfunctional monomer were added. After 19.8 g of ether, the temperature was raised to 60 ° C, and nitrogen substitution was carried out in the system by nitrogen aeration for 30 minutes. The temperature in the reaction tank was adjusted to 60 ° C, and 2.5 g of 2,2'-azobis(isobutyronitrile) was added to initiate polymerization. The polymerization temperature was maintained at 60 ° C during the polymerization. After 3 hours, when the polymerization rate of vinyl acetate reached 58%, the polymerization was stopped by cooling. Next, unreacted vinyl acetate was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate (hereinafter, abbreviated as PVAc). The PVAc thus obtained was purified by reprecipitation using acetone as a good solvent and hexane as a poor solvent, and dried by vacuum drying. Thereafter, the obtained PVAc was dissolved in heavy chloroform, and ¹ H-NMR measurement was performed. The measurement results are shown in Fig. 1. From the obtained spectrum of Fig. 1, the amount of introduction of the ethylenic double bond to the total of the vinyl alcohol unit and the vinyl acetate unit was 0.5 mol%. By adding methanol to the obtained methanol solution of PVAc, the concentration of the solution was adjusted to 30% by mass, and the alkali molar ratio (the number of moles of NaOH/the number of moles of the vinyl ester unit in PVAc) was 0.006. Saponification was carried out with a NaOH methanol solution (10% strength). The obtained vinyl alcohol-based copolymer was washed with methanol.

From the above operation, a vinyl alcohol-based copolymer having a viscosity average degree of polymerization of 1070 and a degree of saponification of 79.6 mol% was obtained. The obtained vinyl alcohol-based copolymer was dissolved in water at 90 ° C to prepare a 4% by mass aqueous solution, which was completely dissolved. Further, the obtained vinyl alcohol-based copolymer was dissolved in dimethyl hydrazine and subjected to ¹ H-NMR measurement. The measurement results are shown in Fig. 2. From the obtained spectrum of Fig. 2, the introduction amount of the ethylenic double bond in the total of the vinyl alcohol unit and the vinyl acetate unit was calculated to be 0.5 mol%.

(Synthesis of an ethylene acetal polymer having an ethylenic double bond in its side chain)

480 g of PVA-1 was placed in 5,520 mL of water, and the temperature of the solution was raised to 90 ° C while stirring to dissolve, and then cooled to 30 ° C. To the aqueous solution, 400 g of a 20% aqueous hydrochloric acid solution was added. Thereafter, the aqueous solution was cooled to 14 ° C, and butyl aldehyde 267 g was dropped for 10 minutes to start the reaction. After reacting at 14 ° C for 40 minutes, the temperature was raised to 65 ° C at a temperature increase rate of about 0.6 ° C / minute, and maintained at 65 ° C for 300 minutes. Thereafter, the reaction solution was cooled to room temperature, and the precipitated granules were filtered off, and then washed thoroughly with water. The obtained product was poured into a 0.3% sodium hydroxide solution, and the mixture was heated at 70 ° C to carry out neutralization. The product was continuously washed with water to remove the basic compound, and the resultant was dried to obtain an ethylene acetal polymer (VAP-1).

The degree of acetalization of the obtained ethylene acetal polymer VAP-1 was measured and found to be 70.2 mol%. Further, the viscosity of the 5% by mass ethanol/water (95% by mass/5 mass%) solution of the obtained ethylene acetal polymer was the value shown in Table 2. Further, using the above-described 5% by mass ethanol/water (95% by mass/5 mass%) solution to cast film forming method A film having a thickness of 100 μm was produced, and the film was measured for tensile strength. The results are shown in Table 2.

[Examples 2 to 7]

The vinyl alcohol-based copolymers PVA-2 to PVA-7 were obtained in the same manner as in Example 1 except that the type and amount of the polyfunctional monomer to be used and the amount of vinyl acetate and methanol added were as shown in Table 1. The evaluation results of the vinyl alcohol copolymers PVA-2 to PVA-7 are shown in Tables 1 and 2. Further, in the same manner as in Example 1, except that PVA-1 was used instead of PVA-1, ethylene acetal-based polymers VAP-2 to VAP-7 were obtained. The evaluation results of the ethylene acetal polymer VAP-2 to VAP-7 are shown in Table 2. Further, the amount of the ethylenic double bond relative to the vinyl alcohol unit of VAP-6 and its derivative (vinyl acetate unit and acetal unit) is the same as that of the vinyl alcohol polymer, and ¹ H- The NMR measurement was 0.2 mol%, and there was no difference in the amount of the ethylenic double bond in the vinyl alcohol-based polymer of the starting material.

[Example 8]

An ethylene acetal-based polymer VAP-8 was obtained in the same manner as in Example 7 except that the amount of butyl aldehyde added was reduced. The evaluation results of the ethylene acetal polymer VAP-8 are shown in Table 2.

[Example 9]

An ethylene acetal-based polymer VAP-9 was obtained in the same manner as in Example 7 except that the amount of butyl aldehyde added was increased. Ethylene acetal polymer VAP-9 The evaluation results are shown in Table 2.

[Example 10]

The vinyl alcohol-based copolymer PVA-8 was obtained in the same manner as in Example 1 except that the type and amount of the polyfunctional monomer to be used were as shown in Table 1. An ethylene acetal-based polymer VAP-10 was obtained in the same manner as in Example 1 except that the PVA-1 was used instead of the vinyl alcohol-based copolymer PVA-8. The evaluation results of the ethylene acetal polymer VAP-10 are shown in Table 2.

[Comparative Examples 1 and 2]

The vinyl alcohol-based copolymers PVA-C1 and PVA-C2 were obtained in the same manner as in Example 1 except that the amount of vinyl acetate and methanol added was changed without using a polyfunctional monomer. The evaluation results of the vinyl alcohol copolymers PVA-C1 and PVA-C2 are shown in Tables 1 and 2. Ethylene acetal polymers VAP-C1 and VAP-C2 were obtained in the same manner as in Example 1 except that the PVA-1 was replaced with the PVA-1, and the vinyl alcohol copolymers PVA-C1 and PVA-C2 were used. The evaluation results of the ethylene acetal polymers VAP-C1 and VAP-C2 are shown in Table 2.

[Comparative Example 3]

The vinyl alcohol-based copolymer PVA-C3 was obtained in the same manner as in Example 1 except that the amount of the polyfunctional monomer added was changed as shown in Table 1. The evaluation results of the vinyl alcohol copolymer PVA-C3 are shown in Table 1 and Table 2. The same as in Example 1 except that the PVA-1 was used instead of the vinyl alcohol copolymer PVA-C3. The ethylene acetal polymer VAP-C3 was obtained. The evaluation results of the ethylene acetal polymer VAP-C3 are shown in Table 2.

[Comparative Example 4]

The vinyl alcohol-based copolymer PVA-C4 was obtained in the same manner as in Example 1 except that the amount of the acetaldehyde, the vinyl acetate, and the methanol added was as shown in Table 1, except that the polyfunctional monomer was replaced. The evaluation results of the vinyl alcohol copolymer PVA-C4 are shown in Table 1 and Table 2. An ethylene acetal-based polymer VAP-C4 was obtained in the same manner as in Example 1 except that the PVA-1 was replaced with the vinyl alcohol-based copolymer PVA-C4. The evaluation results of the ethylene acetal polymer VAP-C4 are shown in Table 2.

Claims (6)

An ethylene acetal polymer which is an ethylene acetal polymer obtained by acetalizing a vinyl alcohol copolymer obtained by saponifying a copolymer of vinyl acetate and a polyfunctional monomer, and is characterized by The polyfunctional monomer contains two or more ethylenic double bonds in the molecule, and the vinyl alcohol-based copolymer has an ethylenic group in which the side chain contains an ethylenic double bond and the total of the vinyl alcohol unit and the vinyl acetate unit. The molar ratio (d) of the double bond is 0.05/100 to 2/100, and the degree of acetalization is 45 to 80 mol%. The ethylene acetal polymer according to claim 1, wherein the side chain contains a vinyl ether group. The ethylene acetal polymer according to claim 1 or 2, wherein the side chain contains an allyl group. A method for producing an ethylene acetal polymer according to claim 1 or 2, which comprises the step of copolymerizing vinyl acetate with a polyfunctional monomer to obtain a vinyl ester copolymer, and the vinyl ester system The step of saponifying the copolymer to obtain a vinyl alcohol-based copolymer and the step of acetalizing the vinyl alcohol-based copolymer. The method for producing an ethylene acetal polymer according to claim 4, wherein the molar ratio (p) of the polyfunctional monomer to the vinyl acetate when the vinyl acetate is copolymerized with the polyfunctional monomer is 0.1/100~5/100. The method for producing an ethylene acetal polymer according to claim 5, wherein the vinyl alcohol polymer has a molar ratio of a vinyl double bond to a total of a vinyl alcohol unit and a vinyl acetate unit. The ratio (d/p) of the molar ratio (d) of the polyfunctional monomer to the vinyl acetate relative to the vinyl ester copolymer is 0.2 to 0.8.