TWI625337B - Ethylene acetal polymer - Google Patents

Abstract

An object of the present invention is to provide a vinyl acetal polymer having excellent solubility in an alcohol-based solvent and the like, and adhesion to inorganic substances such as glass, and at the same time having a low solution viscosity and excellent handleability. The present invention is an ethylene acetal-based polymer, which is an ethylene acetal-based polymer obtained by acetalizing a vinyl alcohol-based polymer, and is characterized in that the vinyl alcohol-based polymer includes a compound having the following formula ( 1) The monomer unit of the group shown below satisfies the following formula (I), and the degree of acetalization is 45 mol% or more and 80 mol% or less. The vinyl alcohol-based polymer preferably satisfies the following formulae (II) and (III).

370 ≦ P × S ≦ 6,000… (I)

200 ≦ P ≦ 4,000… (II)

0.1 ≦ S ≦ 10 ... (III)

P: viscosity average polymerization degree

S: content ratio of the above-mentioned monomer unit (mole%)

Description

Ethylene acetal polymer

The present invention relates to an ethylene acetal polymer.

An ethylene acetal polymer represented by a vinyl butyral polymer is a product obtained by acetalizing a vinyl alcohol polymer (hereinafter sometimes referred to as "PVA"), and has strong toughness and film formation. It is excellent in dispersibility such as added inorganic or organic powder. Therefore, the above-mentioned vinyl acetal polymers can be used for interlayer films, inks, coatings, enamels for glazing, rust-cutting primers, coatings, dispersants, adhesives, ceramic green sheets, thermal imaging Various applications such as sexy light materials and adhesives for water-based ink receiving layers.

In order to improve the adhesiveness with glass, ceramics, or inorganic substances in addition to the aforementioned characteristics of the above-mentioned ethylene acetal-based polymers, it has been proposed to use silane-modified ethylene acetal-based polymers (hereinafter, there are (Referred to as "silyl group-containing ethylene acetal polymer") (refer to Japanese Patent Application Laid-Open No. 2005-194409). However, the above-mentioned silane-containing ethylene acetal-based polymer has the disadvantage of being extremely difficult to handle due to its extremely low solubility in organic solvents such as alcohol-based solvents, and even when dissolved, its solution viscosity is high.

Prior art literature Patent literature

Patent Document 1 Japanese Patent Application Laid-Open No. 2005-194409

[Summary of Invention]

The present invention is based on the above-mentioned reasons. The purpose of the present invention is to provide an ethylene acetal polymer which is excellent in solubility to alcohol solvents and the like and adhesion to inorganic substances such as glass, and has low solution viscosity and excellent handling properties.

The invention is made to solve the above-mentioned problem: an ethylene acetal polymer, which is an ethylene acetal polymer obtained by acetalizing a vinyl alcohol polymer, wherein the vinyl alcohol polymer contains A monomer unit having a group represented by the following formula (1), which satisfies the following formula (I), and has an acetalization degree of 45 mol% or more and 80 mol% or less;

(In formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; R ² is a group represented by an alkoxy group, a fluorenyloxy group, or an OM; M is a hydrogen atom, an alkali metal, or an ammonium group; R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group; the hydrogen atom of the alkyl group, alkoxy group, and fluorenyl group represented by R ¹ to R ⁴ may be replaced by a substituent containing an oxygen atom or a nitrogen atom; m is an integer of 0 to 2; n is an integer of 3 or more; in the case where R ¹ to R ⁴ exist in a plural number, each of the R ¹ to R ^{4 in a} plural number is independent and meets the above definition); 370 ≦ P × S ≦ 6,000 ... (I)

P: viscosity average polymerization degree

S: content rate (mole%) of the above-mentioned monomer unit.

The ethylene acetal polymer is obtained by acetalizing PVA, and the PVA includes a monomer unit having a group represented by the formula (1), and has a silane group via an alkylene group having 3 or more carbon atoms. Structure connected to the main chain. Therefore, the ethylene acetal-based polymer has sufficient solubility in alcohol-based solvents and the like even if the quality of the silane group is improved, and its solution viscosity can be reduced. Although the reason for this effect has not been fully identified, it is speculated as follows. If the previous silane-containing PVA is acetalized by an acid, the silanol groups will undergo a cross-linking reaction with each other during the acetalization process. As a result, the obtained ethylene acetal-based polymer is an alcohol-based solvent. Very low solubility. However, the above-mentioned PVA has a structure in which a silane group is connected to the main chain through an alkylene group specified in the present invention, so it is presumed that the progress of the cross-linking reaction between the silane groups is inhibited during the acetalization process. As a result, the obtained acetal-based polymer is a substance having sufficient solubility in an alcohol-based solvent and the like, and having a reduced solution viscosity. In addition, if the ethylene acetal polymer is used, the product (P × S) of the average viscosity polymerization degree (P) of the PVA and the content rate (S) of the monomer unit is within the above-mentioned range, so it can be improved. The silane group changes the quality, and can effectively exert the characteristics derived from the silane group, such as adhesion to inorganic substances such as glass. In addition, by setting the degree of acetalization to 45 mol% or more and 80 mol% or less, the solubility of the ethylene acetal-based polymer to an alcohol-based solvent and the like can be improved.

The PVA preferably satisfies the following formulae (II) and (III): 200 ≦ P ≦ 4,000… (II)

0.1 ≦ S ≦ 10 ... (III)

P: viscosity average polymerization degree

S: content rate (mole%) of the above-mentioned monomer unit.

Thus, by setting the viscosity average polymerization degree (P) of the PVA and the content rate (S) of the monomer unit to the above range, the solubility of the ethylene acetal polymer to an alcohol solvent or the like can be made. And the adhesion to inorganic materials such as glass is more improved, and the viscosity of the solution can be further reduced.

It is preferable that n in the said Formula (1) is an integer of 6-20. By setting the value of n to the above range, the cross-linking reaction of the silanol groups in the acetalization process can be more suppressed, and the solubility in alcohol solvents and the like can be further improved, even at a high degree of polymerization. In some cases, the modification rate of silane groups can also be improved.

The monomer unit is preferably represented by the following formula (2):

(In formula (2), R ¹ to R ⁴ , m and n have the same definitions as in formula (1); X is a direct bond, a divalent hydrocarbon group, or a divalent organic group containing an oxygen atom or a nitrogen atom; R ⁵ Is a hydrogen atom or a methyl group).

Since the above-mentioned monomer unit system has a structure represented by the above formula (2), the properties of the ethylene acetal-based polymer can be further improved.

X in the above formula (2) is preferably represented by the following formula (3): -CO-NR ^6- * ... (3)

(In the formula (3), R ⁶ is a hydrogen atom or an alkyl group having 1 to 5 carbons; * represents a bond with the group represented by the formula (1)).

R ⁶ in the formula (3) is a hydrogen atom, and n in the formula (2) is preferably an integer of 3 to 12. By setting the above-mentioned monomer unit to such a structure, the solubility of the ethylene acetal-based polymer to an alcohol-based solvent and the like can be further improved, and the solution viscosity can be further reduced. In addition, the production of the PVA can be easily performed.

The aldehyde used for acetalization is preferably at least one selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, hexanal, and benzaldehyde, and particularly preferred is butyraldehyde. By using such an aldehyde, the above-mentioned acetalization of PVA can be performed efficiently.

As described above, the ethylene acetal polymer of the present invention is excellent in solubility to alcohol solvents and the like and adhesion to inorganic substances such as glass, and has low solution viscosity and excellent operability. Therefore, the ethylene acetal polymer is suitable for use in a laminated glass intermediate film composition, a slurry composition for a ceramic capacitor electrode paste, a ceramic green sheet slurry composition, and an ink composition. Various applications, such as coating composition, adhesive composition, and thermal imaging material composition.

[Form for Implementing Invention] <Ethylene acetal polymer>

The ethylene acetal polymer of the present invention is obtained by acetalizing PVA, and the PVA includes a monomer unit having a group represented by the formula (1), and has a silane group via an alkylene having 3 or more carbon atoms. Based on the structure connected with the main chain. Therefore, the ethylene acetal-based polymer has sufficient solubility in alcohol-based solvents and the like even if the quality of the silane group is improved, and its solution viscosity can be reduced. Although the reason for this effect has not been fully identified, it is speculated as follows. If the previous PVA containing a silane group is acetalized by an acid, the silanol groups will undergo a cross-linking reaction with each other during the acetalization process. As a result, the obtained ethylene acetal polymer is an alcohol-based solvent. Very low solubility. However, the above-mentioned PVA has a structure in which a silane group is connected to the main chain through an alkylene group specified in the present invention, so it is presumed that the progress of the cross-linking reaction between the silane groups during the acetalization is suppressed, As a result, the obtained acetal-based polymer is a substance having sufficient solubility in an alcohol-based solvent and the like, and having a reduced solution viscosity. In addition, if the ethylene acetal polymer is used, the product (P × S) of the average viscosity polymerization degree (P) of the PVA and the content rate (S) of the monomer unit is within the above-mentioned range, so it can be improved. The silane group changes the quality, and can effectively exert the characteristics derived from the silane group, such as adhesion to inorganic substances such as glass. In addition, by setting the degree of acetalization to 45 mol% or more and 80 mol% or less, the solubility of the ethylene acetal-based polymer to an alcohol-based solvent and the like can be improved.

<PVA>

The PVA includes a monomer unit having a group represented by the formula (1). That is, the PVA is a copolymer of a monomer unit having a group represented by the formula (1) and a vinyl alcohol unit (-CH ₂ -CHOH-), and may further have other monomer units.

In the formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group.

R ² is a group represented by alkoxy, fluorenyloxy or OM. M is a hydrogen atom, an alkali metal or an ammonium group ⁽⁺ NH _4). Examples of the alkoxy group include a methoxy group and an ethoxy group. Examples of the fluorenyloxy group include ethoxyl and propylfluorenyl. Examples of the alkali metal include sodium and potassium. Among these groups represented by R ² , an alkoxy group or a group represented by OM is preferable, an alkoxy group having 1 to 5 carbon atoms, and M is a hydrogen atom or an alkali metal represented by OM. The group is more preferably a group represented by OM in which methoxy, ethoxy and M are sodium or potassium.

R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group. Examples of the alkyl group include the above-mentioned alkyl groups having 1 to 5 carbon atoms. R ³ and R ⁴ are preferably a hydrogen atom or a methyl group.

The hydrogen atom system of the alkyl group, alkoxy group, and fluorenyl group represented by R ¹ to R ⁴ may be substituted with a substituent containing an oxygen atom or a nitrogen atom. Examples of the substituent containing an oxygen atom include alkoxy and fluorenyloxy. Examples of the substituent containing a nitrogen atom include an amine group and a cyano group.

Furthermore, in the case where R ¹ to R ⁴ exist as plural numbers, each of the R ¹ to R ^{4 in} plural numbers independently satisfy the above definition.

m is an integer from 0 to 2, but is preferably 0. m is 0, that is, the above-mentioned monomer unit can improve the effect caused by silane group by having three R ² groups.

n is an integer of 3 or more. For PVA having n less than 3, if a basic compound is not added, it is difficult to dissolve in water of an acetalization solvent, and acetalization in an acidic aqueous solution cannot be performed. Although the upper limit of n is not particularly limited, it is preferably 20, more preferably 15 and even more preferably 12. The lower limit of n is preferably 4, more preferably 6 and even more preferably 8. The ethylene acetal polymer of the present invention produced from such a PVA is connected to a main chain via an alkylene group having a silyl group via a carbon number of 3 or more, that is, n in the formula (1) where n is 3 or more. The structured PVA is obtained by acetalization, and even if the quality of the silane group is improved, it has sufficient solubility to alcohol solvents and the like, and can reduce its solution viscosity. Although the reason for this effect has not been fully identified, it is speculated as follows. If the previous silane-containing PVA is acetalized by an acid, the silanol groups will undergo a cross-linking reaction with each other during the acetalization process. As a result, the obtained ethylene acetal-based polymer is an alcohol-based solvent. Very low solubility. However, the above-mentioned PVA has a structure in which a silane group is connected to the main chain through an alkylene group specified in the present invention, so it is presumed that the progress of the cross-linking reaction between the silane groups during the acetalization is suppressed, As a result, the obtained acetal-based polymer is a substance having sufficient solubility in an alcohol-based solvent and the like, and having a reduced solution viscosity.

The specific structure of the monomer unit is not particularly limited as long as it has a base represented by the formula (1), but is preferably represented by the formula (2).

In formula (2), the definitions of R ¹ to R ⁴ , m, and n are the same as those in formula (1). These preferred bases or numerical ranges are also the same.

X is a direct bond, a divalent hydrocarbon group, or a divalent organic group containing an oxygen atom or a nitrogen atom. Since the above-mentioned monomer unit has a structure represented by the above formula (2), the properties of the ethylene acetal-based polymer can be further improved.

Examples of the divalent hydrocarbon group include a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and a divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. Examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include methylene, ethylidene, and propylidene. Examples of the divalent aromatic hydrocarbon group having 6 to 10 carbon atoms include phenylene and the like. Examples of the divalent organic group containing an oxygen atom include an ether group, an ester group, a carbonyl group, an amido group, and a group in which these groups are connected to a divalent hydrocarbon group. Examples of the above-mentioned divalent organic group containing a nitrogen atom include an imine group, amidino group, and a group in which these groups are connected to a divalent hydrocarbon group.

Among the groups represented by X, a divalent organic group containing an oxygen atom or a nitrogen atom is preferable, a group containing a sulfonylamino group, and still more preferably -CO-NR ^6- * (R ⁶ is A hydrogen atom or an alkyl group having 1 to 5 carbons; * represents a group represented by a bond with the group represented by the formula (1)). In this way, because the above-mentioned monomer unit has a polar structure at a position separated from the silane group, preferably a fluorene amine structure, the properties derived from the silane group can be maintained, and the ethylene acetal polymer can be made. The solubility of alcohol-based solvents and the like is further improved, and the acquisition of monomers becomes easier, and the viscosity of the solution can be further reduced. In addition, in terms of R ⁶ , a hydrogen atom is preferred from the viewpoint of further improving the above-mentioned function or facilitating the production of the PVA.

R ⁵ is a hydrogen atom or a methyl group.

The monomer unit is more preferably represented by the following formula (4).

In the formula (4), the definitions of R ¹ , R ² , R ⁵ , X, and m are the same as those in the formula (2). These preferred bases or numerical ranges are also the same.

In the formula (4), R ³ ′ and R ⁴ ′ are each independently a hydrogen atom or an alkyl group. Examples of the alkyl group include the above-mentioned alkyl groups having 1 to 5 carbon atoms. R ³ ′ and R ⁴ ′ are preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom. The hydrogen atom of the alkyl group represented by R ³ ′ and R ⁴ ′ may be substituted with a substituent containing an oxygen atom or a nitrogen atom. Examples of the substituent containing an oxygen atom include alkoxy and fluorenyloxy. Examples of the substituent containing a nitrogen atom include an amine group and a cyano group. In addition, when R ³ ′ and R ⁴ ′ each exist in a plural number, each of the plural R ³ ′ and R ⁴ ′ independently satisfies the above definition.

In the above formula (4), n 'is an integer of 1 or more. The upper limit of n 'is not particularly limited, but is preferably 18, more preferably 13 and even more preferably 10. The lower limit of n 'is preferably 2, more preferably 4 and even more preferably 6.

In the case where the monomer unit is represented by the formula (4), the functions of the ethylene acetal polymer can be more effectively expressed.

The PVA satisfies the following formula (I): 370 ≦ P × S ≦ 6,000… (I)

P: viscosity average polymerization degree

S: content ratio of the above-mentioned monomer unit (mole%)

The viscosity average polymerization degree (P) is measured in accordance with JIS-K6726. That is, in the case where the degree of saponification is less than 99.5 mol%, the above-mentioned PVA is re-saponified to a degree of saponification above 99.5 mol%, and after purification, the limiting viscosity [η] (units) can be measured from water at 30 ° C : Deciliter / g) is calculated by the following formula: P = ([η] × 1000 / 8.29) ^{(1 / 0.62)}

The viscosity average polymerization degree of the ethylene acetal-based polymer can be obtained from the viscosity average polymerization degree P of the PVA used in production. That is, since the degree of polymerization is not changed by the acetalization described later, the average degree of polymerization of the viscosity of the PVA is the same as that of the ethylene acetal polymer obtained by acetalizing the same.

The content ratio (S: mole%) of the above-mentioned monomer units was obtained from proton NMR of a vinyl ester polymer before saponification. Among them, when measuring the proton NMR of the vinyl ester polymer before saponification, the vinyl ester polymer was purified by reprecipitation with hexane-acetone, and the unreacted monomer having a silane group was sufficiently removed from the polymer. Then, it was dried under reduced pressure at 90 ° C for 2 days, and then dissolved in a CDCl ₃ solvent for analysis.

In addition, the content rate (S: mole%) of the above-mentioned monomer unit of the ethylene acetal-based polymer is determined from the content rate (S: mole%) of the above-mentioned monomer unit of the PVA used for production. Got. That is, because The content rate of the monomer unit is not changed by the acetalization described later. The content rate of the monomer unit of the PVA and the monomer content of the ethylene acetal polymer obtained by acetalizing the monomer unit are not changed. The body unit content is the same.

The product (P × S) of the average viscosity degree of polymerization (P) and the content rate (S) of the monomer units is equivalent to the number (average value) of the monomer units per 100 molecules. When the product (P × S) is smaller than the lower limit described above, the properties derived from silane groups such as the adhesiveness of the ethylene acetal-based polymer to inorganic substances such as glass cannot be fully utilized. Conversely, if the product (P × S) exceeds the above upper limit, the solubility to alcohol-based solvents and the like decreases. The product (P × S) preferably satisfies the following formula (I ′), and more preferably satisfies the following formula (I ”): 400 ≦ P × S ≦ 3,000… (I ′)

500 ≦ P × S ≦ 2,000 ... (I ”).

The PVA preferably satisfies the following formulae (II) and (III): 200 ≦ P ≦ 4,000… (II)

0.1 ≦ S ≦ 10 ... (III)

P: viscosity average polymerization degree

S: content rate (mole%) of the above-mentioned monomer unit.

In this way, by setting the viscosity average degree of polymerization (P) and the content ratio (S) of the monomer units to the above ranges, the solubility of the ethylene acetal polymer to alcohol solvents and the like and the glass The adhesion of other inorganic substances is improved, and the viscosity of the solution can be further reduced.

Furthermore, in the viscosity average polymerization degree (P), it is more preferable to satisfy the following formula (II '), and it is even more preferable to satisfy the following formula (II "). 500 ≦ P ≦ 3,000… (II ’)

1,000 ≦ P ≦ 2,400 ... (II ”).

When the viscosity average degree of polymerization (P) is less than the above-mentioned lower limit, the effect derived from silane groups, such as adhesion to inorganic substances such as glass, may be reduced. Conversely, when the viscosity average degree of polymerization (P) exceeds the above-mentioned upper limit, the solubility of the ethylene acetal-based polymer to alcohol-based solvents and the like and the adhesion to inorganic substances such as glass may decrease.

The content ratio of the monomer unit is more preferably to satisfy the following formula (III '), and even more preferably to satisfy the following formula (III "), 0.25 ≦ S ≦ 6 ... (III ′)

0.5 ≦ S ≦ 5 ... (III ”).

When the content rate (S) of the above-mentioned monomer unit is less than the above-mentioned lower limit, the effect of a silyl group on the adhesion to an inorganic substance such as glass may decrease. On the contrary, when the content ratio (S) of the monomer unit exceeds the upper limit, the solubility of the ethylene acetal polymer to an alcohol solvent and the like and the adhesiveness to an inorganic substance such as glass may be reduced.

As far as the saponification degree of the above PVA is not particularly limited, it is preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and particularly preferably 97 mol%. the above. The degree of saponification of the PVA is less than the lower limit described above, and the effect of the adhesion to glass, ceramics, and inorganic substances by a silane group may decrease. The upper limit of the saponification degree of the PVA is not particularly limited, but it is, for example, 99.9 mol% in consideration of productivity. Here, the degree of saponification of PVA is a value measured in accordance with the method described in JIS-K6726.

<Manufacturing method of PVA>

Although the manufacturing method of the said PVA is not specifically limited, For example, the obtained copolymer can be copolymerized by copolymerizing a vinyl ester-type monomer with the monomer which has the group represented by said formula (1). (Vinyl ester polymer) obtained by saponification.

Examples of the vinyl ester-based monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, and benzoic acid. Vinyl ester, trimethyl vinyl acetate, ethylene tert-carbonate, and the like. Among these, vinyl acetate is preferred.

In addition, when a monomer having a group represented by the formula (1) is copolymerized with a vinyl ester-based monomer, the purpose of adjusting the viscosity average polymerization degree (P) of the obtained PVA, etc., is to Within the scope of the purpose of the present invention, polymerization can be performed in the presence of a chain transfer agent. Examples of the chain transfer agent include aldehydes such as acetaldehyde and propionaldehyde; ketones such as acetone and methyl ethyl ketone; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, Thiols such as 2-hydroxyethyl mercaptan, n-dodecanethiol, mercaptoacetic acid, and 3-mercaptopropionic acid; halogenated hydrocarbons such as tetrachloromethane, bromotrichloromethane, trichloroethylene, and perchloroethylene.

Examples of the monomer having a group represented by the formula (1) include a compound represented by the following formula (5). By using a compound represented by the following formula (5), finally, a PVA containing a monomer unit having a group represented by the formula (2) can be easily obtained.

In the formula (5), the definitions of R ¹ to R ⁵ , X, m, and n are the same as those in the formula (2). These preferred bases or numerical ranges are also the same.

Examples of the compound represented by the formula (5) include 3- (meth) acrylamidopropyltrimethoxysilane, 4- (meth) acrylamidobutyltrimethoxysilane, and 6 -(Meth) acrylamidohexyltrimethoxysilane, 8- (meth) acrylamidooctyltrimethoxysilane, 12- (meth) acrylamidododecyltrimethoxysilane, 18- ( (Meth) acrylamidooctadecyltrimethoxysilane, 3- (meth) acrylamidopropyltriethoxysilane, 3- (meth) acrylamidopropyltributoxysilane, 3- (Meth) acrylamidopropylmethyldimethoxysilane, 3- (meth) acrylamidopropyldimethylmethoxysilane, 3- (meth) acrylamido-3-methyl Butyltrimethoxysilane, 4- (meth) acrylamido-4-methylbutyltrimethoxysilane, 4- (meth) acrylamido-3-methylbutyltrimethoxysilane, 5 -(Meth) acrylamido-5-methylhexyltrimethoxysilane, 4-pentenyltrimethoxysilane, 5-hexenyltrimethoxysilane, and the like.

As a method for copolymerizing the vinyl ester-based monomer and a monomer having a group represented by the formula (1), known methods include a block polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. method. In particular, when the polymerization temperature is lower than 30 ° C, an emulsion polymerization method is preferred. When the polymerization temperature is 30 ° C or higher, a block polymerization method in which a solvent is not used or a solution polymerization method in which a solvent such as an alcohol is used is generally adopted.

In the case of the emulsion polymerization method, the solvent may be water, or a lower alcohol such as methanol or ethanol may be used in combination. As the emulsifier, a known emulsifier can be used. As for the initiator during the copolymerization, a redox-based initiator in which an iron ion-oxidant-reducing agent is used in combination for controlling polymerization is suitable. In the case of a block polymerization method or a solution polymerization method, when a copolymerization reaction is performed, the reaction method can be implemented in either a batch method or a continuous method. When the copolymerization reaction is performed by a solution polymerization method, examples of the alcohol used as a solvent include lower alcohols such as methanol, ethanol, and propanol. Examples of the initiator used in the copolymerization reaction in this case include 2,2'-azobisisobutyronitrile and 2,2'-azobis (2,4-dimethylvaleronitrile). ), 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (N-butyl-2-methylpropylamidamine), etc. ; Well-known initiators such as peroxide-based initiators such as benzamidine peroxide and n-propyl peroxycarbonate. The polymerization temperature during the copolymerization reaction is not particularly limited, but it is preferably in the range of 5 ° C to 70 ° C.

In this copolymerization reaction, as long as it is within a range not detrimental to the purpose of the present invention, a copolymerizable monomer can be copolymerized as needed. Examples of such monomers include α-olefins such as ethylene, propylene, 1-butene, isobutylene, and 1-hexene; fumaric acid, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, and the like Carboxylic acid or its derivative; acrylic acid or its salt, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate and other acrylates; methacrylic acid or its salt, methyl methacrylate, methacrylic acid Ethyl ester, n-propyl methacrylate, isopropyl methacrylate Isomethacrylates; acrylamide derivatives such as acrylamide, N-methacrylamide, N-ethyl acrylamide; methacrylamide, N-methacrylamide, N -Methacrylamide derivatives such as ethyl methacrylamide; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether ); Ethylene glycol ethers, 1,3-propylene glycol vinyl ether, 1,4-butanediol vinyl ether, and other vinyl ethers containing hydroxyl groups; allyl acetate; propyl allyl ether, butyl allyl Allyl ethers, such as alkyl ethers and hexyl allyl ethers; monomers having oxyalkylene groups; isopropenyl acetate; 3-buten-1-ol, 4-penten-1-ol, 5-hexyl Α-olefins containing hydroxyl groups such as ene-1-ol, 7-octen-1-ol, 9-decene-1-ol, 3-methyl-3-butene-1-ol; vinyl sulfonic acid , Allylic sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid and other monomers having sulfonic acid groups; vinyl chloride oxyethyl trimethylammonium, chlorine Vinyloxybutyltrimethylammonium, vinyloxyethyldimethylamine, vinyloxymethyldiethyl Amine, N-acrylamide methyltrimethylammonium chloride, N-acrylamide ethyltrimethylammonium chloride, N-acrylamide dimethylamine, allyltrimethylammonium chloride, A monomer having a cationic group such as methyl allyl trimethyl ammonium chloride, dimethyl allyl amine, allyl ethyl amine, and the like. As for the amount of these monomers, although it varies with the purpose or use of the monomer, the proportion based on the total monomers used for copolymerization is usually 20 mol% or less, preferably 10 mol. Ear%.

The vinyl ester polymer obtained by the above-mentioned copolymerization is then saponified in a solvent according to a known method to form PVA.

As a catalyst for a saponification reaction, an alkaline substance is generally used, and examples thereof include hydrogen of alkali metals such as potassium hydroxide and sodium hydroxide. Oxides, and alkali metal alkoxides such as sodium methoxide. The amount of the basic substance used is based on the molar ratio of the vinyl ester monomer unit in the vinyl ester polymer, and is preferably in the range of 0.004 to 0.5, and more preferably in the range of 0.005 to 0.05. . The catalyst may be added together at the initial stage of the saponification reaction, or a part may be added at the initial stage of the saponification reaction, and the rest may be added during the saponification reaction.

Examples of the solvent that can be used for the saponification reaction include methanol, methyl acetate, dimethyl sulfene, diethyl sulfene, and dimethylformamide. Among these solvents, methanol is preferred. When using methanol, it is preferable to adjust the water content in methanol to be preferably 0.001 to 1% by mass, more preferably 0.003 to 0.9% by mass, and particularly preferably 0.005 to 0.8% by mass.

The saponification reaction is preferably performed at a temperature of 5 ° C to 80 ° C, and more preferably at a temperature of 20 ° C to 70 ° C. The time required for the saponification reaction is preferably 5 minutes to 10 hours, and more preferably 10 minutes to 5 hours. The saponification reaction can be carried out by either a batch method or a continuous method. After the saponification reaction is completed, the remaining saponification catalyst may be neutralized as needed. Examples of usable neutralizers include organic acids such as acetic acid and lactic acid, and ester compounds such as methyl acetate.

The PVA obtained by the saponification reaction can be washed if necessary. Examples of the washing liquid used in this washing include low-carbon alcohols such as methanol, low-carbon fatty acid esters such as methyl acetate, and mixtures thereof. A small amount of water, alkali, or acid may be added to these cleaning solutions.

As for the pH of the PVA aqueous solution, the pH of the aqueous solution containing the PVA at a concentration of 8% by mass is preferably 4 or more and 8 or less, more preferably 4.5 or more and 7 or less, and still more preferably 5 or more and 6.5. the following. Since the PVA has excellent solubility in water, a uniform aqueous solution can be obtained without adding an alkali or an acid such as sodium hydroxide to water. As a result, the ethylene acetal polymer can be easily obtained from the PVA.

<Manufacture of ethylene acetal polymer>

The ethylene acetal polymer of the present invention is obtained by acetalizing the PVA obtained as described above in accordance with a conventionally known method. The degree of acetalization at this time must be 45 mol% or more and 80 mol% or less. By setting the degree of acetalization to the above range, the ethylene acetal-based polymer can fully exhibit properties derived from silane groups, and can improve solubility in alcohol-based solvents and the like. The acetalization degree of the ethylene acetal polymer is preferably 55 mol% or more and 80 mol% or less, and more preferably 60 mol% or more and 80 mol% or less. When adjusting the acetalization degree of the ethylene acetal polymer, it is only necessary to appropriately adjust the amount of aldehyde added to the PVA used, the reaction time after adding the aldehyde and the acid catalyst, and the like.

Here, the degree of acetalization of the ethylene acetal-based polymer refers to the ratio of the acetalized vinyl alcohol unit to the total monomer units constituting the ethylene acetal-based polymer. The acetalization degree can be measured according to, for example, the method of JIS K6728 (1977).

Examples of the method for acetalizing the PVA include (1) heating and dissolving the PVA in water to prepare an aqueous solution having a concentration of 5 to 30% by mass, cooling the solution to 5 ° C to 50 ° C, and then adding A method in which a set amount of aldehyde is cooled to -10 ° C to 30 ° C, and the pH of the aqueous solution is lowered to 1 by adding an acid to start acetalization; (2) the PVA is heated and dissolved in water to adjust the concentration to 5-30% by mass of an aqueous solution is cooled to 5 ° C to 50 ° C, and the pH of the aqueous solution is made to be 1 or less by adding an acid, A method of cooling to -10 ° C to 30 ° C and adding a predetermined amount of aldehyde to start acetalization.

Examples of the aldehyde used for acetalization include formaldehyde (including paraformaldehyde), acetaldehyde (including paraacetaldehyde), propanal, butyraldehyde, isobutyraldehyde, 2-ethylbutyraldehyde, Aliphatic aldehydes such as n-valeraldehyde, trimethylacetaldehyde, valeraldehyde, hexanal, heptaldehyde, 2-ethylhexanal, octanal, nonanal, decylaldehyde, and dodecyl aldehyde; cyclopentanal, formaldehyde Cyclopentaldehyde, dimethylcyclopentanal, cyclohexanal, methylcyclohexanal, dimethylcyclohexanal, cyclohexaneacetaldehyde, and other alicyclic aldehydes; cyclopentenal, cyclohexenal, etc. Cyclic unsaturated aldehydes; benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, dimethylbenzaldehyde, methoxybenzaldehyde, phenylacetaldehyde, β-benzene Propionaldehyde, p-isopropylbenzaldehyde, naphthaldehyde, anthracenaldehyde, cinnamaldehyde, crotonaldehyde, acrolein, 7-octene-1-aldehyde and other aldehydes containing aromatic or unsaturated bonds; furfural, methylfurfural And other heterocyclic aldehydes.

Among these, at least one selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, hexanal, and benzaldehyde, and particularly preferred is butyraldehyde. By using such an aldehyde, the acetalization of the PVA can be performed more efficiently.

Moreover, in the range which does not impair the effect of this invention, you may use the aldehyde which has a functional group, such as a hydroxyl group, a carboxyl group, a sulfonic acid group, and a phosphate group.

The acid used for acetalization is not particularly limited, but 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, hydrochloric acid and nitric acid are more preferred, and two or more of these may be used in combination. In addition, the time required for the acetalization reaction is usually about 1 hour to 10 hours. Better than stirring. When the acetalization is performed under the above-mentioned temperature conditions, the reaction can be continued at a high temperature of about 50 ° C to 80 ° C without increasing the acetalization degree of the ethylene acetal-based polymer.

The granular reaction product obtained after acetalization is filtered and separated, and it is sufficiently washed with water. A neutralizing agent such as an alkali is added, washed, and dried to obtain the desired ethylene acetal polymer. Examples of the alkali compound used as the neutralizing agent include sodium hydroxide and potassium hydroxide.

The ethylene acetal polymer of the present invention produced in this manner is excellent in solubility to alcohol solvents and the like, and adhesion to inorganic substances such as glass, and has a low solution viscosity and excellent handleability. Therefore, the ethylene acetal-based polymer of the present invention is suitable for bonding an interlayer film composition for glass, a slurry composition for a ceramic capacitor electrode paste, a slurry composition for a ceramic green sheet, and an ink composition. Various applications, such as coating composition, adhesive composition, and thermal imaging material composition.

[Example]

Hereinafter, the present invention will be described in more detail through examples. In the following examples and comparative examples, unless otherwise specified, parts and% represent mass parts and mass%, respectively.

In addition, the monomer having a silane group (monomer A) used in the examples and comparative examples is as follows: MAmPTMS: 3-methacrylamidopropyltrimethoxysilane

MAmOTMS: 8-methacrylamidooctyltrimethoxysilane

VMS: vinyltrimethoxysilane

[Synthesis of Silyl-containing PVA]

The PVA was produced according to the following method, and the saponification degree and the content rate (S) of the monomer unit having the base represented by the formula (1) were determined (in some cases, the content of the monomer unit having a silane group Ratio), viscosity average degree of polymerization (P).

[Analysis method of PVA]

The analysis of PVA is performed in accordance with the method described in JIS-K6726 unless otherwise stated.

[Manufacturing Example 1] Manufacturing of PVA1

In a 6-liter separable flask equipped with a stirrer, a reflux cooling tube, a nitrogen introduction tube, a comonomer drip inlet, and an initiator addition port, 1,500 g of vinyl acetate, 500 g of methanol, and the formula (1) ) Of 1.87 g of MAmPTMS of the monomer (monomer A) shown in the figure), while nitrogen was bubbled into the system for nitrogen substitution for 30 minutes. Furthermore, MAmPTMS was dissolved in methanol to prepare a comonomer solution having a concentration of 8% as a retardation solution, and nitrogen was replaced by bubbling nitrogen gas. The temperature rise of the reactor was started, and when the internal temperature became 60 ° C, 0.8 g of 2,2'-azobisisobutyronitrile (AIBN) was added to start polymerization. The delayed solution was added dropwise while the monomer composition (ratio of vinyl acetate to monomer A (MAmPTMS)) in the polymerization solution was kept constant. After polymerization at 60 ° C. for 2.7 hours, cooling was performed to stop the polymerization. The total amount of the comonomer solution (sequential addition solution) added until the polymerization was stopped was 99 g. The solid content concentration when the polymerization was stopped was 29.0%. Next, methanol was added at any time under reduced pressure at 30 ° C to remove unreacted vinyl acetate monomer to obtain methanol containing 40% of polyvinyl acetate (PVAc) having a group represented by the formula (1). Dissolve liquid. In a further step, methanol and a methanol solution containing 10% by mass of sodium hydroxide are added in this order under stirring, so that the molar ratio of sodium hydroxide to the vinyl acetate unit in PVAc is 0.04, and PVAc is a solid. The component concentration became 30% by mass, and a saponification reaction was started at 40 ° C. After the alkali solution was added, a gel was formed in about 5 minutes. This gel was pulverized with a pulverizer, and left to stand at 40 ° C for 1 hour to allow saponification to proceed, and then methyl acetate was added to neutralize the remaining alkali. After confirming the completion of neutralization with a phenolphthalein indicator, a white solid was obtained by filtration and separation. Methanol was added thereto, and the mixture was left at room temperature for 3 hours and washed. After the above washing operation was repeated three times, the obtained white solid was centrifuged to remove the liquid and left at 65 ° C for 2 days to obtain PVA1 having a base represented by the formula (1). PVA1 has an average viscosity polymerization degree (P) of 1,700 and a saponification degree of 98.6 mole%.

The content rate of the monomer unit having the group represented by the formula (1) (the content rate of the monomer unit having a silane group) of the obtained PVA1 was obtained from proton NMR of PVAc, which is a precursor of the PVA. Specifically, the reprecipitation and purification of the obtained PVAc were performed sufficiently three times or more with n-hexane / acetone, and then dried under reduced pressure at 50 ° C for 2 days to prepare PVAc for analysis. This PVAc was dissolved in CDCl ₃ and measured at room temperature using 500 MHz proton NMR (JEOL GX-500). From the peak α (4.7 to 5.2 ppm) of the methine group in the main chain of the vinyl acetate unit and the peak β (3.4 to 3.8 ppm) of the methoxy group methyl group in the monomer A unit, the The content (S) of the monomer unit of the group represented by the formula (1). In PVA1, the content rate (S) was 0.5 mole%. Table 1 shows the results of analyzing the obtained PVA.

Content ratio of monomer unit having a group represented by formula (1) (S: mole%) = ((peak area of β / 9) / (peak area of α + (peak area of β / 9))} × 100

[Manufacturing Examples 2 and 3, and Comparative Manufacturing Examples 1 to 3] Manufacturing of PVA2 to PVA6

In addition to changing the polymerization conditions such as the amount of vinyl acetate and methanol, the type and amount of monomer A, as shown in Table 1, the concentration of PVAc at the time of saponification, and the mole of sodium hydroxide relative to the vinyl acetate unit Except for other saponification conditions, PVA2 to PVA6 were obtained in the same manner as in Production Example 1. Table 1 shows the results of the analysis of each PVA obtained. In addition, in Table 1, the content rate (S) of Comparative Production Examples 1 to 3 also includes the content rate of the monomer unit having a silane group other than the monomer unit having a group represented by the formula (1).

<Synthesis of Ethylene Acetal Polymer> [Example 1] Synthesis of VAP1

480 g of PVA1 was poured into 5,520 mL of water, and the temperature of the solution was raised to 90 ° C. while being dissolved, and then cooled to 30 ° C. to measure the pH of the aqueous solution. The measured pH of the aqueous solution is shown in Table 2. To this aqueous solution was added 400 g of a 20% strength hydrochloric acid aqueous solution. It was then cooled to 14 ° C, and it took 10 minutes to drip 267 g of butyraldehyde to start the reaction. After carrying out the reaction at 14 ° C for 40 minutes, the temperature was raised to 65 ° C at a rate of about 0.6 ° C / min, and maintained at 65 ° C for 300 minutes. Then, the reaction solution was cooled to room temperature, and the precipitated particles were separated by filtration, and the particles were sufficiently washed with water. The obtained product was put into a 0.3% sodium hydroxide solution, and was heated to 70 ° C. for neutralization. After washing with water to remove the basic compound, the product was dried to obtain an ethylene acetal polymer (VAP1). The degree of acetalization of the obtained ethylene acetal-based polymer was analyzed in accordance with the method described in JISK6728, and it was 70.2 mol%.

[Examples 2 and 3, and Comparative Examples 1 to 3] Synthesis of VAP2 to VAP6

Except that the PVA shown in Table 2 was used instead of the PVA used in Example 1, an ethylene acetal polymer (VAP2 to VAP6) was obtained in the same manner as in Example 1. Table 2 shows the pH of the PVA aqueous solution used and the degree of acetalization of each VAP.

<Evaluation of ethylene acetal polymer>

For each of the ethylene acetal polymers prepared as described above, the following physical property values were measured and evaluated.

(Solubility and solution viscosity of ethylene acetal polymer)

By making each ethylene acetal-based polymer in an ethanol / water (95% / 5%) solution, such as 5% by mass, the solubility of each ethylene acetal-based polymer was observed and evaluated visually. The person who completely dissolved was evaluated as “A”, and the prepared solution was stirred at 50 ° C. for 24 hours, and then the obtained solution was filtered and separated using five kinds of C filter paper of JIS P3801 to separate the ethylene acetal system used for the dissolution. When the total amount of the polymer of the ethylene acetal polymer remaining on the filter paper is 0.01% or more and less than 99%, it is evaluated as "B", and the total amount of the ethylene acetal polymer remaining in the dissolution is remained in When the mass ratio of the ethylene acetal-based polymer on the filter paper was 99% or more, it was evaluated as "C" as almost insoluble. The results are shown in Table 2. When the ethylene acetal polymer is completely dissolved, the obtained solution is left in a constant temperature bath at 20 ° C. for more than 2 hours, and the viscosity of the solution (mPa.s) is measured using a Brookfield viscometer. If the solution viscosity is less than 400 (mPa.s), it can be evaluated that the solution viscosity is depressed. The results are shown in Table 2 together.

(Adhesion to glass)

It was measured by the method described in International Publication No. 2012/026393. The results are shown in Table 2 together.

As shown in Table 2, the ethylene acetal polymers (VAP1 to VAP3) prepared in Examples 1 to 3 have excellent solubility in organic solvents such as alcohols and adhesion to glass, and the viscosity of the obtained solutions Department was depressed.

On the other hand, when the ethylene acetal-based polymer does not satisfy the prescribed requirements (Comparative Examples 1 to 3), it is almost insoluble in organic solvents such as alcohol (Comparative Examples 1 and 2), or even if it is soluble in When an organic solvent such as an alcohol is dissolved, it is also a substance having poor adhesion to glass (Comparative Example 3).

[Industrial availability]

The ethylene acetal polymer of the present invention is excellent in solubility to alcohol solvents and the like and adhesion to inorganic substances such as glass, and has low solution viscosity and excellent handleability. Therefore, the ethylene acetal polymer is suitable for use in bonding glass intermediate film composition, slurry composition for ceramic capacitor electrode paste, slurry composition for ceramic green sheet, and ink composition. Various applications, such as coating composition, adhesive composition, and thermal imaging material composition.

Claims (8)

A vinyl acetal polymer is an ethylene acetal polymer obtained by acetalizing a vinyl alcohol polymer. It is characterized in that the vinyl alcohol polymer includes The monomer unit of the group represented by formula (1) satisfies the following formula (I) and formula (III "), and the degree of acetalization is 45 mol% or more and 80 mol% or less; (In formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; R ² is a group represented by an alkoxy group, a fluorenyloxy group, or an OM; M is a hydrogen atom, an alkali metal, or an ammonium group; R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group; the hydrogen atom of the alkyl group, alkoxy group, and fluorenyl group represented by R ¹ to R ⁴ may be replaced by a substituent containing an oxygen atom or a nitrogen atom; m is an integer of 0 to 2; n is an integer of 3 or more; in the case where R ¹ to R ⁴ exist in a plural number, each of the R ¹ to R ^{4 in a} plural number independently meets the above definition); 370 ≦ P × S ≦ 6,000 ... (I) 0.5 ≦ S ≦ 5 ... (III ”) P: viscosity average polymerization degree S: content ratio (mole%) of the monomer unit. For example, the ethylene acetal polymer according to claim 1, wherein the vinyl alcohol polymer further satisfies the following formula (II): 200 ≦ P ≦ 4,000 ... (II) P: viscosity average polymerization degree. For example, the ethylene acetal polymer of claim 1, wherein n in the formula (1) is an integer of 6-20. The ethylene acetal polymer according to claim 1, wherein the monomer unit is represented by the following formula (2): (In formula (2), R ¹ to R ⁴ , m and n have the same definitions as in formula (1); X is a direct bond, a divalent hydrocarbon group, or a divalent organic group containing an oxygen atom or a nitrogen atom; R ⁵ Is a hydrogen atom or a methyl group). The ethylene acetal polymer according to claim 4, wherein X in the formula (2) is represented by the following formula (3): -CO-NR ^6- * (3) (in the formula (3), R ⁶ Is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; * represents a bond with a group represented by the formula (1)). For example, the ethylene acetal polymer according to claim 5, wherein R ⁶ in the formula (3) is a hydrogen atom, and n in the formula (2) is an integer of 3-12. The ethylene acetal polymer according to claim 1, wherein the aldehyde used for acetalization is at least one selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, hexanal and benzaldehyde. The ethylene acetal polymer according to claim 7, wherein the aldehyde used for acetalization is butyraldehyde.