JP2018184569A - Copolymer and Copolymer Composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copolymer that can show suitable properties as a baking binder or the like.SOLUTION: The present invention provides a copolymer containing (a) a constitutional unit derived from a polyvinyl acetal polymerizable compound with a polymerizable unsaturated group and/or thiol group bonded to polyvinyl acetal through ester bond, and (b) a constitutional unit derived from (meth) acrylate, and a copolymer composition and a film molding containing the same.SELECTED DRAWING: None

Description

  The present invention relates to a copolymer and a copolymer composition containing the copolymer.

  The demand for electronic components is increasing due to the electrification of mobile devices such as mobile phones and smartphones and automobiles. In particular, the demand for multilayer ceramic capacitors (referred to as “MLCC”), which is a passive component, is increasing rapidly.

  An example of the production of MLCC is as follows. First, a dielectric ceramic paste is applied on a releasable sheet to produce a green sheet having a dielectric layer. Next, an electrode paste (sometimes referred to as “conductive paste”) is printed on the dielectric layer to form an electrode pattern (electrode layer). Further, the laminate of the dielectric layer and the electrode layer is peeled off from the release sheet, and a plurality of the laminates are laminated and pressure-bonded, and then cut into chips. Next, the obtained chip is heated to several hundred to 1000 ° C. or higher and fired to produce a sintered body chip in which a dielectric layer and an electrode layer are laminated in multiple layers. Finally, external electrodes and the like are formed.

  In recent years, chip size reduction and accompanying reduction in thickness of each layer constituting the chip and miniaturization of printed electrode patterns have been progressing. Under such a background, there is a strong demand for improved adhesion between the layers and excellent printability of the paste used.

  Other electronic components such as a chip inductor and a chip resistor are also manufactured by the same process as MLCC. Also, the manufacturing process of a silicon-based solar cell includes a printing and firing process using an electrode paste in forming a collector electrode.

  A ceramic paste and an electrode paste used for manufacturing an electronic component such as MLCC include a binder (also referred to as a “baked binder” in this specification) that is a polymer material and an organic solvent, and inorganic particles are contained therein. The resin composition is uniformly dispersed. As the inorganic particles, dielectric particles such as barium titanate are used in the ceramic paste, and conductive metal particles such as nickel are used in the electrode paste. Conventionally, polyvinyl butyral has been mainly used for the ceramic paste as the baking binder, and ethyl cellulose has been mainly used for the electrode paste (Patent Document 1).

  As literature which discloses the technique regarding a baking binder, patent documents 2-6 other than patent document 1 are mentioned.

Japanese Patent Publication No. 04-049766 JP 2004-331413 A Japanese Patent No. 4347440 Japanese Patent No. 4581341 Japanese Patent No. 5299904 Japanese Patent No. 4737985

  The objective of this invention is providing the copolymer which can show a suitable characteristic as a baking binder.

The present invention provides the following copolymer, copolymer composition and film molded article.
[1] A structural unit (a) derived from a polyvinyl acetal polymerizable compound in which a polymerizable unsaturated group and / or a thiol group are bonded to polyvinyl acetal via an ester bond;
A structural unit (b) derived from (meth) acrylate;
A copolymer comprising
[2] The content ratio of the structural unit (a) and the structural unit (b) is in the range of 0.5: 9.5 to 9.5: 0.5 on a mass basis, according to [1]. Copolymer.
[3] A copolymer composition comprising the copolymer according to [1] or [2], inorganic particles, and an organic solvent.
[4] A film molding comprising the copolymer according to [1] or [2].

  It is possible to provide a copolymer that can exhibit suitable characteristics as a baking binder or the like.

Hereinafter, the present invention will be described in detail with reference to embodiments.
In the present specification, the description “A to B” (A and B are numerical values) represents “A or more and B or less” unless otherwise specified.
In this specification, “(meth) acrylate” means acrylate and / or methacrylate, and “(meth)” in the case of (meth) acryl, (meth) acryloyl, etc. has the same meaning.

<Copolymer>
The copolymer according to the present invention includes a structural unit (a) derived from a polyvinyl acetal polymerizable compound in which a polymerizable unsaturated group and / or a thiol group (—SH) is bonded to polyvinyl acetal through an ester bond. And a structural unit (b) derived from (meth) acrylate.
The polyvinyl acetal polymerizable compound is polymerized by the polymerizable unsaturated group and / or thiol group to form the structural unit (a) in the copolymer.
(Meth) acrylate is polymerized by the polymerizable unsaturated double bond (vinyl group) to form the structural unit (b) in the copolymer.
A copolymer can contain 1 type, or 2 or more types of structural units (a), and can also include 1 type, or 2 or more types of structural units (b).

  In one embodiment, the copolymer according to the present invention can be used as a binder (baking binder) contained in the paste (or slurry) described above. According to the copolymer composition (paste or slurry) containing the copolymer according to the present invention as a binder, the following problems that the conventional paste (or slurry) and the binder contained therein have had can be solved.

1) Improvement of thermal decomposability (combustibility). If ash such as carbon remains even after the thermal decomposition treatment by firing, the electrical characteristics of electronic components such as MLCC are deteriorated.
2) Improved printability. In recent years, electrode patterns formed by screen printing have been miniaturized and thinned, and the pattern size has fallen below 100 μm. For this reason, in the electrode paste, a binder that does not cause a so-called stringing phenomenon is required. The yarn wrinkle phenomenon is a phenomenon in which a paste used in a printing process is stretched under the influence of a binder polymer and a thin yarn is wound, which causes a defective product.
3) Improvement of uniform dispersibility of inorganic particles, film strength (strength of layer formed from paste) and adhesion between layers. These are required characteristics accompanying the thinning of each layer constituting the chip.

  According to the copolymer of the present invention, the above conventional problems are solved, and the thermal decomposability, printability, uniform dispersion of inorganic particles, film strength of the coating film, film quality of the coating film (formed from paste) It is possible to provide a copolymer composition (paste or slurry) that can improve the homogeneity of the layers) and the adhesion between the layers.

  For example, Patent Documents 3 and 5 described above disclose techniques for improving physical properties such as film strength by blending polyvinyl butyral with ethyl cellulose in an electrode paste. However, the binder obtained by blending ethyl cellulose and polyvinyl butyral is not compatible with these two polymers, and the dispersibility of the inorganic particles when mixing inorganic particles such as metal, ceramic, and glass into a paste or slurry. Low. As a result, the coating film is likely to be defective or the uniformity of the coating film is likely to be reduced. There is also a problem inherent to the material that the thermal decomposition during firing is poor.

  Patent Document 4 describes that a monomer component containing a (meth) acrylic ester uses a graft copolymer obtained by graft polymerization on a cellulose resin having an isocyanate group-containing vinyl monomer as a baking binder. . However, when the inventor conducted a follow-up experiment according to the description in Patent Document 4, it was found that the yield of the calcined binder was poor due to the use of the isocyanate derivative. In addition, there is room for improvement in the thermal decomposability and the homogeneity of the coating film.

  Patent Document 2 describes that a graft copolymer obtained by graft polymerization of a monomer component containing (meth) acrylic acid ester on polyvinyl butyral obtained by reacting an isocyanate group-containing vinyl monomer is used as a baking binder. Yes. However, since the isocyanate group-containing vinyl monomer is used, it has the same problem as the method described in Patent Document 4.

  Patent Document 6 describes that a polyvinyl butyral resin obtained by graft copolymerization of an alkyl (meth) acrylate monomer is used as a baking binder. However, since the graft copolymer obtained by the method described in Patent Document 6 is presumed not to have high grafting efficiency, the homogeneity of the binder itself, the film strength (and density) of the coating film, It is considered that there is a problem in adhesion.

  Moreover, the copolymer which concerns on this invention can be applied to an adhesive agent or a sealing material in other embodiment. The adhesive and the sealing material including the copolymer according to the present invention can exhibit good adhesiveness, and can exhibit high fluidity at the time of melting, and thus can be excellent in handleability.

[1] Structural unit (a)
The polyvinyl acetal polymerizable compound forming the structural unit (a) is a compound in which a polymerizable unsaturated group and / or thiol group is bonded (added) to polyvinyl acetal through an ester bond.
The ester bond can be formed, for example, by a condensation reaction between a hydroxy group of polyvinyl acetal and an organic acid having a polymerizable unsaturated group and / or thiol group.

Polyvinyl acetal is usually a polymer composed of vinyl acetal / vinyl alcohol / vinyl acetate monomer units, and can be obtained by acetalizing polyvinyl alcohol, which is a saponified product of polyvinyl acetate.
Specific examples of the polyvinyl acetal include those obtained by converting polyvinyl alcohol into butyral (polyvinyl butyral) and those obtained by formalizing polyvinyl alcohol (polyvinyl formal).

  Polyvinyl acetal may be a commercial product, and various polyvinyl acetals with different butyralization degree, formalization degree, acetyl group amount, hydroxy group amount and molecular weight are sold by Sekisui Chemical Co., Kuraray, Eastman Chemical Co., Ltd. Has been. Polyvinyl acetal may use only 1 type and may use 2 or more types together.

  From the viewpoint of efficiently producing a polyvinyl acetal polymerizable compound having a polymerizable unsaturated group and / or thiol group, the polyvinyl acetal is preferably soluble in an organic solvent. The polyvinyl acetal is more preferably polyvinyl butyral because of its high solubility in organic solvents.

The number average molecular weight of polyvinyl acetal is a standard polystyrene conversion value by gel permeation chromatography (GPC), preferably in the range of 50,000 to 150,000, and preferably in the range of 10,000 to 100,000. More preferred.
When the number average molecular weight is less than 50,000, the solution viscosity and the melt viscosity become extremely low, and the viscosity of the copolymer composition (paste or slurry) is adjusted, and the melt viscosity of the adhesive and the sealing material is adjusted. In addition, the strength and adhesion of a film obtained by applying and drying the copolymer composition, or the adhesion performance and adhesion performance when applied to an adhesive or a sealing material may be deteriorated.
When the number average molecular weight exceeds 150,000, the solution viscosity and the melt viscosity become extremely large, and it may be difficult to adjust the viscosity of the copolymer composition and the melt viscosity of the adhesive and the sealing material. The printability of the coalesced composition may be reduced.

The glass transition temperature of the polyvinyl acetal is preferably 50 ° C. to 120 ° C., more preferably 55 ° C. to 90 ° C., from the viewpoint of obtaining a copolymer having a glass transition temperature within a preferable range described later.
The glass transition temperature of the polyvinyl acetal and the copolymer is measured by DSC (differential scanning calorimetry), TMA (thermomechanical analysis) or the like.

  The degree of acetalization of polyvinyl acetal is preferably 40 mol% to 85 mol%, more preferably 50 mol% to 80 mol%, from the viewpoint of strength and flexibility. The degree of acetalization (for example, the degree of butyralization of polyvinyl butyral) can be determined according to JIS K 6728.

Polyvinyl acetal has at least one hydroxy group in one molecule. Generally, a polyvinyl acetal has 20 mol%-40 mol% of hydroxy groups as a vinyl alcohol unit which comprises a polymer. This hydroxy group can be used for introducing a polymerizable unsaturated group and / or a thiol group.
A specific example of the polymerizable unsaturated group is a polymerizable carbon-carbon double bond, and preferable examples thereof are a (meth) acrylate group ((meth) acryloyloxy group), a vinyl group, and an allyl group.

  For example, by reacting a hydroxyl group of polyvinyl acetal with a compound having a group capable of reacting with the hydroxyl group and a polymerizable unsaturated group and / or thiol group, the polyvinyl acetal is reacted with a polymerizable unsaturated group and / or thiol group. Thus, it is possible to obtain a polyvinyl acetal polymerizable compound in which a polymerizable unsaturated group and / or a thiol group is bonded to polyvinyl acetal through an ester bond.

Examples of the compound having a group capable of reacting with a hydroxy group and a polymerizable unsaturated group or thiol group include (meth) acrylic acid, maleic acid, crotonic acid, butenetricarboxylic acid, 4-vinylbenzoic acid, 4-ethenylbenzoic acid. , 3-mercaptopropionic acid. Among them, (meth) acrylic acid having excellent reactivity is used.
Only 1 type may be used for the compound which has a group which can react with a hydroxyl group, and a polymerizable unsaturated group, and / or a thiol group, and it may use 2 or more types together. The polyvinyl acetal polymerizable compound may have both a polymerizable unsaturated group and a thiol group.

The number of polymerizable unsaturated groups and thiol groups (referred to as functional groups) introduced into polyvinyl acetal is indicated by the average number of introduced polyvinyl acetals per polymer chain, and the number average molecular weight of polyvinyl acetal is also shown. And can be calculated. Although various values can be taken depending on the properties required for the copolymer, the preferred number of functional groups introduced is 0.5 to 20 per polyvinyl acetal chain. If it is 0.5 or less, the content of the structural unit (a) in the copolymer becomes excessively small, and it is difficult to obtain the required properties (for example, uniformity of the coating film, uniform dispersibility of the inorganic particles, etc.). . If it is 20 or more, it tends to cause gelation and insolubilization in an organic solvent in the production of the copolymer. The gelled copolymer is not preferable as a binder for a paste (or slurry) or as a resin component for an adhesive or a sealing material.
The amount of the polymerizable unsaturated group and thiol group introduced into the polyvinyl acetal can be measured using ¹ H-NMR.

[2] Structural unit (b)
The (meth) acrylate forming the structural unit (b) of the copolymer is a compound having a (meth) acryloyloxy group, preferably a (meth) alkyl acid ester, more preferably a (meth) alkyl acid alkyl ester. .
The (meth) acrylate may have one (meth) acryloyloxy group in the molecule, or may have two or more.
(Meth) acrylate may use only 1 type and may use 2 or more types together.

As (meth) acrylate,
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, C1-C20 alkyl (meth) acrylates such as cyclohexyl (meth) acrylate and lauryl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glyceryl mono ( Hydroxyalkyl (meth) acrylates such as meth) acrylate; N, N-dialkylaminoalkyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; 2- ( T) Acid group-containing (meth) acrylates such as acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl acid phosphate; methoxypolyethylene glycol (meth) acrylate, ethoxy Alkylene oxide modified (meth) acrylate having 1 to 30 repeating alkylene oxide moieties such as polyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, ethoxypolypropylene glycol (meth) acrylate, butoxydiethylene glycol (meth) acrylate Tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, phenoxyethyl (meth) acrylate, Njiru (meth) acrylate, monofunctional (meth) acrylates such as glycidyl (meth) acrylate;
Bifunctional (meth) acrylates such as ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate having 2 to 30 repeating ethylene oxide moieties, and hexanediol di (meth) acrylate;
Trifunctional or higher functional (meth) acrylates such as pentaerythritol tri (meth) acrylate are exemplified.

  The (meth) acrylate may be composed only of a monofunctional (meth) acrylate, or may be composed of a monofunctional (meth) acrylate and a polyfunctional (meth) acrylate. When the (meth) acrylate contains a polyfunctional (meth) acrylate, from the viewpoint of suppressing gelation in the production of the copolymer, the content is 0. It is preferable that it is 1 mass%-5 mass%.

  The type of (meth) acrylate used is the solubility of the resulting copolymer in an organic solvent, the physical properties of the copolymer (glass transition temperature, etc.), the dispersibility of inorganic particles in the paste (or slurry), and the film molding It is preferable to select appropriately in consideration of the physical properties (thermal meltability, mechanical strength, etc.) of the molded product when it is processed into a shape.

When the structural unit (b) contains the structural unit (b1) derived from an alkylene oxide-modified (meth) acrylate, it is clear from the study of the present inventors that it is advantageous for improving the thermal decomposability of the copolymer. Yes.
Specific examples of the alkylene oxide-modified (meth) acrylate include, as described above, methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, ethoxypolypropylene glycol (meth) acrylate, butoxydiethylene glycol It is an alkylene oxide-modified (meth) acrylate in which the number of repeating alkylene oxide moieties such as (meth) acrylate is 1 to 30.
The number of repeating alkylene oxide moieties is preferably 1-20.
Only one type of alkylene oxide-modified (meth) acrylate may be used, or two or more types may be used in combination.
The content of the structural unit (b1) derived from the alkylene oxide-modified (meth) acrylate is preferably 1% by mass to 50% by mass, more preferably 5% by mass when the total amount of the structural unit (b) is 100% by mass. -40 mass%. When the content of the structural unit (b1) is within the above range, thermal decomposability can be improved while ensuring good printability, uniformity of the coating film, uniform dispersibility of inorganic particles, and the like.

[3] Other structural units (c)
The copolymer can further contain a structural unit (c) other than the structural unit (a) and the structural unit (b). The copolymer can contain 1 type, or 2 or more types of structural units (c). By further containing the structural unit (c), it may be easy to adjust the properties of the copolymer.

  Examples of the monomer having a polymerizable unsaturated group forming the structural unit (c) include aromatic vinyl monomers such as styrene, vinyltoluene, α-methylstyrene, p-methylstyrene, and divinylbenzene; olefins such as ethylene and propylene. Monomers: (meth) acrylamides such as (meth) acrylamide and (meth) acryloylmorpholine; (meth) acrylic acid, crotonic acid, cinnamic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride And acids such as citraconic acid and citraconic anhydride; N-vinylpyrrolidone, N-phenylmaleimide, N-cyclohexylmaleimide, (meth) acrylonitrile, vinyl chloride, vinyl acetate and the like.

[4] Constitution of copolymer The content ratio of the constitutional unit (a) and constitutional unit (b) contained in the copolymer is preferably 0.5: 9.5 to 9.5 on a mass basis. : 0.5, more preferably 1: 9 to 9: 1, and even more preferably 2: 8 to 8: 2.
When the content ratio of the structural unit (a) and the structural unit (b) is in the above range, the desired effect due to the copolymer containing the structural unit (a) and the structural unit (b) can be obtained. It can be obtained more effectively. If the content ratio is out of the above range, the intrinsic physical properties of the polyvinyl acetal or (meth) acrylic polymer may be manifested, and any one or more of the desired properties may be deteriorated.

The content of the structural unit (c) in the copolymer is preferably 100 parts by mass or less, more preferably 50 parts by mass with respect to 100 parts by mass of the total content of the structural unit (a) and the structural unit (b). Hereinafter, it is more preferably 10 parts by mass or less.
When the structural unit (c) is in the above range, the desired effect due to the copolymer containing the structural unit (a) and the structural unit (b) can be easily obtained. From this viewpoint, the copolymer may be composed of the structural unit (a) and the structural unit (b).

The molecular weight of the (meth) acrylic polymer copolymerized with polyvinyl acetal is preferably selected from the range of 1000 to 500,000 in terms of the weight average molecular weight per polymer chain to be formed.
The said weight average molecular weight is a standard polystyrene conversion value by GPC.
When the weight average molecular weight is in the above range, the desired effect due to the copolymer containing the structural unit (a) and the structural unit (b) can be easily obtained.
When the weight average molecular weight is less than 1000, the viscosity of the copolymer composition (paste or slurry) is lowered, and the strength and adhesion of the coating film may be lowered.
When the weight average molecular weight exceeds 500,000, the viscosity tends to be too high, the printability may be lowered, and the film may be difficult to be molded.

The weight average molecular weight of a copolymer is a standard polystyrene conversion value by GPC, Preferably it is 10,000-500,000, More preferably, it is 10,000-250,000, More preferably, it is 20,000-200,000.
When the weight average molecular weight of the copolymer is less than 10,000, the viscosity of the copolymer composition (paste or slurry) is decreased, and the strength and adhesion of the coating film may be decreased.
When the weight average molecular weight of the copolymer exceeds 500,000, the viscosity tends to be too high, printability may be lowered, and molding into a film molded product may be difficult.

Although the glass transition temperature of a copolymer can take a various value with the characteristic calculated | required by a copolymer, Preferably it is -10 degreeC-100 degreeC, More preferably, it is 0 degreeC-80 degreeC.
When the glass transition temperature is in the above range, it is advantageous for improving the adhesion performance and adhesion performance when applied to an adhesive or a sealing material. It becomes easy to adjust the heat melting property and mechanical strength of the film molded product containing the polymer to a suitable range.
Further, the glass transition temperature being in the above range is advantageous for improving the printability of the paste or slurry and the strength and adhesion of the coating film.

<Method for producing copolymer>
The copolymer according to the present invention comprises the following steps:
In the presence of a condensing agent, polyvinyl acetal is reacted with a compound having a polymerizable unsaturated group and / or a thiol group, which can react with the hydroxyl group of the polyvinyl acetal, to form a polyvinyl acetal via an ester bond. A first step of obtaining a polyvinyl acetal polymerizable compound having a polymerizable unsaturated group and / or a thiol group bonded thereto, and a polyvinyl acetal polymerizable compound obtained in the first step and (meth) acrylate It can be suitably produced by a method comprising a second step of copolymerizing the monomer composition.

[1] First Step A polyvinyl acetal polymerizable compound in which a polymerizable unsaturated group and / or a thiol group is bonded to a polyvinyl acetal via an ester bond, which forms the structural unit (a) of the copolymer, In the presence of a condensing agent, it can be obtained by reacting a hydroxyl group of polyvinyl acetal with a compound having a polymerizable unsaturated group and / or a thiol group and a group capable of reacting with the hydroxyl group.

  By using a condensing agent, the reaction can be performed in a low temperature environment in which the decomposition of polyvinyl acetal does not occur, and the reaction can be advanced with high efficiency even in a low temperature environment. Specific examples of the organic acid having a polymerizable unsaturated double bond and the cellulose derivative are as described above.

Examples of the condensing agent include carbodiimide, diphenyl phosphate azide, 1-hydroxybenzotriazole, BOP reagent and the like. Only 1 type may be used for a condensing agent and it may use 2 or more types together.
Among these, carbodiimide is preferable because it is excellent in versatility and reactivity and can advance the reaction under low temperature conditions and without being affected by moisture in the reaction environment.

Examples of the carbodiimide include dicyclohexylcarbodiimide, diisopropylcarbodiimide, N- [3- (dimethylamino) propyl] -N′-ethylcarbodiimide, N- [3- (dimethylamino) propyl] -N′-ethylcarbodiimide methiodide, N -Tert-butyl-N'-ethylcarbodiimide and the like.
Among these, dicyclohexylcarbodiimide and diisopropylcarbodiimide are preferable from the viewpoint of availability.
When carbodiimide is used, it is also preferable to use dimethylaminopyridine, triethylamine or the like as a base as a reaction accelerator in a range of 0.01 mol% to 10 mol% with respect to carbodiimide.

  From the viewpoint of reactivity, the reaction in this step should be carried out in an aprotic organic solvent after preparing an aprotic organic solvent solution of polyvinyl acetal using an aprotic organic solvent capable of dissolving polyvinyl acetal. Is preferred.

Examples of the aprotic organic solvent capable of dissolving polyvinyl acetal include ethyl acetate, butyl acetate, hexyl acetate, tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, toluene, xylene, dimethylformamide, dimethylacetamide, N- Methyl pyrrolidone, ethyl lactate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate (butyl carbitol acetate), diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol ethyl methyl ether, diethylene glycol isopropylmethyl Ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, propylene glycol monomethyl ether acetate, propylene glycol dimethyl ether, propylene glycol diacetate, dipropylene glycol dimethyl ether, tripropylene glycol Examples thereof include dimethyl ether and dihydroterpinyl acetate.
Only one type of aprotic organic solvent may be used, or two or more types may be used in combination.

  The concentration of polyvinyl acetal in the aprotic organic solvent solution of polyvinyl acetal is preferably in the range of 5% by mass to 50% by mass, although it depends on the molecular weight.

The temperature of the reaction between the hydroxy group of the polyvinyl acetal, the compound having a group capable of reacting with the hydroxy group, and a polymerizable unsaturated group and / or thiol group is, for example, about 0 ° C. to 100 ° C., preferably 0 ℃ -60 ℃. The reaction time is usually 3 hours to 72 hours, preferably 6 hours to 48 hours.
When carbodiimide is used as the condensing agent, urea may be generated as a by-product and insolubilized in some cases, but filtration purification or reprecipitation purification may be performed as necessary.

The progress of the reaction can be quantitatively grasped by measuring the acid value over time.
The total amount of polymerizable unsaturated groups and thiol groups introduced into the polyvinyl acetal can be measured by NMR analysis or the like.
The preferred range of the total amount of polymerizable unsaturated groups and thiol groups introduced into the polyvinyl acetal is as described above.
The above total amount is appropriately adjusted with the number of moles of the condensing agent used relative to the number of moles of the hydroxy group possessed by the polyvinyl acetal, or with a group capable of reacting with the hydroxy group of the polyvinyl acetal in an equimolar amount with respect to the condensing agent This can be realized by adding and reacting a compound having an unsaturated group and / or a thiol group.

[2] Second Step This step is a step of copolymerizing a monomer composition containing the polyvinyl acetal polymerizable compound obtained in the first step and (meth) acrylate.
Specifically, in the second step, a monomer having a polymerizable unsaturated group that forms at least the predetermined (meth) acrylate or further the structural unit (c) is added to the reaction solution obtained by the reaction in the first step. It can be a step of adding and performing a copolymerization reaction in the presence of a radical polymerization initiator.
The copolymerization reaction is performed, for example, by heating in an organic solvent in the presence of a radical polymerization initiator, preferably in a non-oxygen atmosphere.

In the copolymerization reaction, the organic solvent may be replaced with or added from the organic solvent in the first step. The organic solvent to be substituted or added may be an aprotic organic solvent or a protic organic solvent. As the radical polymerization initiator, conventionally known ones (for example, peroxides and azos) can be used.
The usage-amount of a radical polymerization initiator is the range of 0.001 mass%-5 mass% with respect to 100 mass% of total amounts of a monomer, for example.

Protic organic solvents include ethyl alcohol, isopropyl alcohol, butyl alcohol, benzyl alcohol, isoborneol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol Examples include monomethyl ether, terpineol, dihydroterpineol and the like.
Only one type of protic organic solvent may be used, or two or more types may be used in combination.

  The total concentration of all monomers in the copolymerization reaction solution is preferably 5% by mass to 70% by mass. The temperature of the copolymerization reaction is, for example, about 40 ° C to 120 ° C.

  After the copolymerization reaction, an ordinary polymer purification treatment such as precipitation purification with a poor solvent may be performed as necessary. By the purification treatment, unreacted monomers and by-products can be removed, and a solid state copolymer can be obtained. Furthermore, it is also preferable to obtain a solid product by removing the organic solvent by heating or decompression after the reaction.

<Copolymer composition>
In one embodiment according to the present invention, the copolymer composition includes a binder that is the copolymer, inorganic particles, and an organic solvent, and various pastes or slurries, particularly electronic components and electronic devices. It is suitable as a baking paste or slurry for producing members, substrates and the like.
In addition, although there is no clear distinction between a paste and a slurry, it is distinguished mainly from the point of viscosity, and the former is higher viscosity.
According to the copolymer composition (paste or slurry) containing the copolymer according to the present invention as a binder, thermal decomposability, printability, uniform dispersibility of inorganic particles, film strength of the coating film, film quality of the coating film ( The homogeneity of the layer formed from the paste) and the adhesion between the layers can be improved.

  For example, the copolymer composition can be suitably used as a paste or slurry for forming circuits, electrode patterns, dielectric layers, phosphor layers and the like of various electronic components. In addition, a copolymer composition containing a binder and an organic solvent, which can be a production intermediate of the copolymer composition, also belongs to the present invention.

Examples of the inorganic material constituting the inorganic particles contained in the copolymer composition include conductive inorganic materials, ceramics, glass, pigments, and phosphors.
Examples of the conductive inorganic material include metals such as gold, silver, copper, platinum, palladium, nickel, aluminum, tungsten, and iron; alloys containing any of the above metals such as silver-palladium alloys; metals made of ITO or the like Oxides; carbon powder and the like.
Examples of the ceramic include magnetic ceramics such as barium titanate, titanium oxide, alumina, zirconia, aluminum nitride, silicon nitride, boron nitride, silicon carbide, and ferrite.
Examples of the glass include those containing silicon dioxide (usually those containing silicon dioxide as a main component), and the melting point thereof is not particularly limited.
The particle diameter of the inorganic particles is usually in the range of 20 nm to 1 mm.
Only one type of inorganic particles may be used, or two or more types may be used in combination.

  As the organic solvent contained in the copolymer composition, one or more of the organic solvents exemplified in the above <Method for producing copolymer> [1] and [2] can be used. The organic solvent is preferably a solvent capable of dissolving the binder, and preferably has a high boiling point in printing paste applications.

  It is preferable to use an organic solvent having a boiling point of 100 ° C. or higher. When using 2 or more types of organic solvents together, it is preferable that the boiling point of all the organic solvents is 100 degreeC or more.

The copolymer composition may further contain an additive as necessary. Additives include surfactants, viscosity modifiers, antifoaming agents, leveling agents, stabilizers, plasticizers, wetting agents, dyes, polymer particles, and the like.
Only 1 type may be used for an additive and it may use 2 or more types together. Further, the copolymer composition may contain a polymer other than the above-mentioned copolymer as a part of the binder.

The content ratio of the inorganic particles in the copolymer composition (when two or more inorganic particles are contained, the total content thereof) and the binder is usually 100: 1 to 100: 50 on a mass basis. From the viewpoint of the viscosity of the polymer composition and the dispersibility of the inorganic particles, the ratio is preferably 100: 5 to 100: 30.
The content of the organic solvent (when two or more organic solvents are contained, the total content thereof) is usually 100 parts by mass to 10,000 parts by mass with respect to 100 parts by mass of the binder.
When the copolymer composition contains an additive, its content (when two or more additives are contained, its total content) is usually 0.1 parts by mass to 100 parts by mass of the binder. 30 parts by mass.

  Inorganic particles, a binder (copolymer) dissolved in an organic solvent, and additives used as necessary are mixed using a dispersing device such as a three-roll mill, a ball mill, a media mill, or a homogenizer, and the inorganic particles are mixed. A copolymer composition can be prepared by uniformly dispersing the copolymer composition.

  After coating the copolymer composition on a substrate or the like, the organic solvent is volatilized by subsequent baking, and the binder is thermally decomposed to form a layer or pattern of inorganic particles. Examples of the coating method for the copolymer composition include screen printing, die coating printing, doctor blade printing, roll coating printing, offset printing, gravure printing, flexographic printing, inkjet printing, dispensing printing, casting method, dip coating, and the like. Of these, screen printing and dip coating are preferred. The layer or pattern obtained by firing usually comprises a sintered body of inorganic particles.

<Film molded body>
The film molded body according to the present invention includes the copolymer. This film molded body can be used as, for example, an adhesive film (adhesive sheet), a sealing material film (sealing material sheet), or the like. In adhesive applications, the copolymer according to the present invention can be an adhesive component. In a sealing material application, the copolymer according to the present invention can be a sealing resin component.
The film molding can be a hot-melt adhesive or sealing material that is melted by heat and applied to a desired position.

  The film molded body can be produced by melt-molding a resin composition containing the copolymer according to the present invention or cast molding using a solution containing the copolymer.

  Content of the copolymer in a film molded object is 50 mass%-100 mass% in 100 mass% of film molded objects, Preferably it is 60 mass%-100 mass%.

The film molded body can contain components other than the copolymer. Moreover, the form by which the film molded object containing this copolymer was laminated | stacked on the releasable film may be sufficient as a film molded object.
Components other than copolymers include antioxidants, UV absorbers, plasticizers, dyes, adhesion-imparting agents, polymerizable monomers and oligomers, polymerization initiators by heat and light, epoxy resins, and epoxy resins. Examples thereof include fillers such as curing agents, polymer fine particles and inorganic material fine particles.

  Since the film molded body contains the copolymer according to the present invention, it can exhibit good characteristics in adhesiveness, adhesion to an object to be sealed, fluidity at the time of melting, and the like.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further more concretely, this invention is not limited by these examples. In the examples, “%” and “part” representing the content or the amount used are based on mass unless otherwise specified.

(Synthesis Example 1: Synthesis of polyvinyl acetal polymerizable compound (a1))
A solution prepared by dissolving 100 parts of polyvinyl butyral (“BH-S” manufactured by Sekisui Chemical Co., Ltd., number average molecular weight Mn (standard polystyrene equivalent by GPC): 66000, glass transition temperature: 64 ° C.) in 900 parts of ethyl acetate. Was prepared.
In the obtained solution, 0.71 part of methacrylic acid, 1.04 part of diisopropylcarbodiimide as a condensing agent (about 6 functional groups introduced per polymer chain), 0.0025 of dimethylaminopyridine as a reaction accelerator Parts were added and mixed, and the mixture was stirred at a temperature of 30 ° C. for 24 hours to carry out a reaction to obtain a solution containing the polyvinyl acetal polymerizable compound (a1). The progress of the reaction was confirmed by acid value measurement, and the reaction was complete after 24 hours.
After the reaction, a small sample was taken from the reaction mixture, dried, and subjected to ¹ H-NMR analysis. As a result, formation of an ester bond was confirmed, and a methacrylate group having the same molar amount as the charged amount was introduced into polyvinyl butyral. It has been confirmed.

(Synthesis Example 2: Synthesis of polyvinyl acetal polymerizable compound (a2))
Instead of polyvinyl butyral ("BH-S" manufactured by Sekisui Chemical Co., Ltd.), polyvinyl butyral ("BM-S" manufactured by Sekisui Chemical Co., Ltd.), number average molecular weight Mn (standard polystyrene conversion value by GPC): 53000 The glass transition temperature: 60 ° C.) was used in the same manner as in Synthesis Example 1 to obtain a solution containing the polyvinyl acetal polymerizable compound (a2).
After the reaction, ¹ H-NMR analysis was performed in the same manner as in Synthesis Example 1. As a result, formation of an ester bond was confirmed, and it was confirmed that a methacrylate group having the same molar amount as the charged amount was introduced into polyvinyl butyral. It was done.

(Synthesis Example 3: Synthesis of polyvinyl acetal polymerizable compound (a3))
Other than using 1.42 parts of methacrylic acid, using 2.08 parts of diisopropylcarbodiimide (about 11 functional groups introduced per polymer chain), and using 0.005 parts of dimethylaminopyridine. In the same manner as in Synthesis Example 1, a solution containing the polyvinyl acetal polymerizable compound (a3) was obtained.
After the reaction, ¹ H-NMR analysis was performed in the same manner as in Synthesis Example 1. As a result, formation of an ester bond was confirmed, and it was confirmed that a methacrylate group having the same molar amount as the charged amount was introduced into polyvinyl butyral. It was done.

(Synthesis Example 4: Synthesis of polyvinyl acetal polymerizable compound (a4))
Instead of polyvinyl butyral ("BH-S" manufactured by Sekisui Chemical Co., Ltd.), polyvinyl butyral ("BM-S" manufactured by Sekisui Chemical Co., Ltd.) was used in the same manner as in Synthesis Example 3, A solution containing the polyvinyl acetal polymerizable compound (a4) was obtained.
After the reaction, ¹ H-NMR analysis was performed in the same manner as in Synthesis Example 1. As a result, formation of an ester bond was confirmed, and it was confirmed that a methacrylate group having the same molar amount as the charged amount was introduced into polyvinyl butyral. It was done.

(Synthesis Example 5: Synthesis of polyvinyl acetal polymerizable compound (a5))
Polyvinyl acetal in the same manner as in Synthesis Example 1 except that 0.88 part of 3-mercaptopropionic acid (the number of introduced functional groups of about 6 per polymer chain) was used instead of 2.83 parts of methacrylic acid. A solution containing the system polymerizable compound (a6) was obtained.
After the reaction, ¹ H-NMR analysis was performed in the same manner as in Synthesis Example 1. As a result, formation of an ester bond was confirmed, and it was confirmed that a thiol group having the same molar amount as the charged amount was introduced into polyvinyl butyral. It was done.

(Synthesis Example 6: Synthesis of polyvinyl acetal polymerizable compound (a6))
Instead of polyvinyl butyral ("BH-S" manufactured by Sekisui Chemical Co., Ltd.), polyvinyl butyral ("BM-S" manufactured by Sekisui Chemical Co., Ltd.) was used in the same manner as in Synthesis Example 5, A solution containing the polyvinyl acetal polymerizable compound (a6) was obtained.
After the reaction, ¹ H-NMR analysis was performed in the same manner as in Synthesis Example 1. As a result, formation of an ester bond was confirmed, and it was confirmed that a thiol group having the same molar amount as the charged amount was introduced into polyvinyl butyral. It was done.

(Synthesis Example 7: Synthesis of polyvinyl acetal polymerizable compound (a7))
1.75 parts of 3-mercaptopropionic acid was used, 2.08 parts of diisopropylcarbodiimide (about 11 functional groups introduced per polymer chain), and 0.005 part of dimethylaminopyridine A solution containing the polyvinyl acetal polymerizable compound (a7) was obtained in the same manner as in Synthesis Example 5 except that it was used.
After the reaction, ¹ H-NMR analysis was performed in the same manner as in Synthesis Example 1. As a result, formation of an ester bond was confirmed, and it was confirmed that a thiol group having the same molar amount as the charged amount was introduced into polyvinyl butyral. It was done.

(Synthesis Example 8: Synthesis of polyvinyl acetal polymerizable compound (a8))
Instead of polyvinyl butyral ("BH-S" manufactured by Sekisui Chemical Co., Ltd.), polyvinyl butyral ("BM-S" manufactured by Sekisui Chemical Co., Ltd.) was used in the same manner as in Synthesis Example 7, A solution containing the polyvinyl acetal polymerizable compound (a8) was obtained.
After the reaction, ¹ H-NMR analysis was performed in the same manner as in Synthesis Example 1. As a result, formation of an ester bond was confirmed, and it was confirmed that a thiol group having the same molar amount as the charged amount was introduced into polyvinyl butyral. It was done.

<Example 1>
[1] Preparation of copolymer 100 parts by mass (solid content concentration is 10% by mass) of the polyvinyl acetal polymerizable compound (a1) -containing liquid obtained in Synthesis Example 1, 8 parts by mass of isobutyl methacrylate, 2-hydroxyethyl methacrylate 2 parts by mass and 0.1 part by mass of azoisobutyronitrile (AIBN) as a polymerization initiator are added to the reaction vessel and mixed, and the inside of the reaction vessel is sufficiently replaced with nitrogen gas, and then polymerized at 70 ° C. for 8 hours. The reaction was carried out. After completion of the polymerization reaction, the solvent was removed by drying under reduced pressure to obtain a solid state copolymer (1).

The weight average molecular weight by GPC of the copolymer (1) was 290,000 in terms of polystyrene, and was larger than 250,000 of polyvinyl butyral (“BH-S” manufactured by Sekisui Chemical Co., Ltd.). This shows that a (meth) acrylic polymer is copolymerized with polyvinyl butyral.
The weight average molecular weights of polyvinyl butyral and the obtained copolymer were measured under the following conditions (the same applies to the following examples and comparative examples).
GPC device: “HLC-8320GPC” manufactured by Tosoh Corporation
Column: TSKgel GMHXL
Measurement temperature (set temperature): 30 ° C
Mobile phase: tetrahydrofuran

It was 60 degreeC when the glass transition temperature Tg of the copolymer (1) was measured.
The glass transition temperature was measured by DSC.
The polyvinyl acetal polymerizable compound used, the glass transition temperature, the weight average molecular weight, and the like of the obtained copolymer are summarized in Table 1 (Copolymer (2) to Copolymer prepared in Examples 2 to 20 described later) The union (20) is also summarized in Table 1.)

The details of the abbreviations listed in Table 1 are as follows.
iBMA: Isobutyl methacrylate HEMA: 2-hydroxyethyl methacrylate DGMA: methoxydiethylene glycol methacrylate MMA: methyl methacrylate BMA: butyl methacrylate LMA: lauryl (meth) acrylate

In Table 1, “PVAc-based polymerizable compound” means a polyvinyl acetal-based polymerizable compound.
“PVAc / acrylic mass ratio” refers to the mass ratio of the structural unit (a) derived from the polyvinyl acetal polymerizable compound and the structural unit (b) derived from (meth) acrylate in the copolymer.
“Acrylic composition” refers to the composition (mass ratio) of (meth) acrylate forming the structural unit (b).

[2] Preparation of copolymer composition The copolymer (1) obtained in [1] above is dissolved in dihydroterpinyl acetate, and the copolymer (1) concentration is 15% by mass. A polymer composition (solution) was prepared.
Next, 10 parts by mass of Ni particles (“NFP201S” manufactured by JFE Mineral Co., Ltd., average particle size of 0.2 μm) as inorganic particles and 3.5 parts by mass of the copolymer composition (solution) are mixed by a three roll mill. Thus, a copolymer composition (paste) was obtained.

[3] Evaluation Regarding the copolymer (1) obtained in the above [1], the copolymer composition (solution) and the copolymer composition (paste) obtained in the above [2], the following items: Evaluation was performed. The results are shown in Table 2.

[3-1] Uniformity of copolymer composition (solution) After the preparation of the copolymer composition (solution), the copolymer composition (solution) that was allowed to stand at 25 ° C for 24 hours was visually observed, Transparency (white turbidity) was evaluated based on the following evaluation criteria.

(Transparency evaluation criteria)
A: No cloudiness is observed B: Slightly cloudy C: High cloudiness

[3-2] Printability (stringiness)
After inserting a metal rod having a diameter of 2 mm and a length of 10 cm into the copolymer composition (solution), the time for winding the yarn when it was pulled up at a speed of 1 cm / sec was measured, and the printability was determined based on the following evaluation criteria. (Yarn property) was evaluated.

(Evaluation criteria for printability)
A: No yarn thread is recognized B: The thread length is less than 2 seconds C: The thread length is 2 seconds or more

[3-3] Homogeneity of coating film The copolymer composition (solution) was coated on a glass substrate with a blade coater having a thickness gap of 30 μm, and the coating film after heating and drying was observed with an optical microscope. The homogeneity of the coating film was evaluated based on the criteria. For the optical microscope, “OLS400” manufactured by Olympus was used, and the coating film was observed at a magnification of 1070 times.

(Evaluation criteria for coating film homogeneity)
A: A sea-island type phase separation structure (a structure in which the other polymer component is distributed in an island shape in the sea of one polymer component) is not observed, or a sea-island type phase separation structure is observed, but the island portion Or larger between the island and the island, the larger one is less than 1 μm B: Sea-island type phase separation structure with a size exceeding 1 μm is observed

[3-4] Thermal decomposability 10 mg of the dry solid sample of the copolymer (1) obtained in the above [1] is transferred to a TG / DTA thermal analyzer (“EXSTAR TG / DTA6200” manufactured by Seiko Instruments Inc.). Then, the amount of residue when heated to 500 ° C. at a rate of temperature increase of 10 ° C./min in a nitrogen atmosphere was measured, and the thermal decomposability of the copolymer (1) was evaluated based on the following evaluation criteria. The amount of residue (% by mass) is an amount when the mass of the dry solid sample is 100% by mass.

(Evaluation criteria for thermal decomposability)
A: The residue cannot be visually observed, and the amount of the residue is zero. B: The amount of the residue is 0.5% by mass or less. C: The amount of the residue is more than 0.5% by mass and less than 2% by mass. D : Residue amount exceeds 2% by mass

[3-5] Uniform dispersibility of inorganic particles A copolymer composition (paste) is applied onto a glass substrate with a blade coater having a thickness gap of 30 μm, and the coating film after heat drying is observed with a scanning electron microscope (SEM). Observing and evaluating the homogeneity of the coating film based on the following evaluation criteria. For the scanning electron microscope, “JSM-7800F” manufactured by JEOL Ltd. was used, and the coating film was observed at a magnification of 5000 times.

(Evaluation criteria for uniform dispersibility of inorganic particles)
A: Defects (holes) larger than 1 μm are not recognized B: Defects (holes) larger than 1 μm are observed

[3-6] Adhesiveness to polyvinyl butyral The copolymer composition (solution) was applied to an easy-adhesion PET film (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd.), dried by heating, 10 cm long, 2 cm wide, and 100 μm thick. Sheet A was prepared.
In addition, a solution of polyvinyl butyral (“BH-3” manufactured by Sekisui Chemical Co., Ltd.) was applied to an easy-adhesive PET film (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd.), dried by heating, 10 cm long, 2 cm wide, membrane A sheet B having a thickness of 100 μm was produced.
Sheet B was overlaid on the surface of the polyvinyl butyral layer on the layer of copolymer (1) in sheet A. At this time, they were overlapped in an area of 1 cm length and 2 cm width.
Subsequently, thermocompression bonding was performed for 5 minutes under the conditions of a temperature of 130 ° C. and a pressure of 2 kg, and the overlapped portions were bonded together to obtain a test piece.
Using a tensile tester (AG-10N) manufactured by Shimadzu Corporation, the test piece was pulled horizontally to measure the breaking strength, and the adhesion to polyvinyl butyral was evaluated based on the following evaluation criteria.

(Evaluation criteria for adhesion to polyvinyl butyral)
A: Break strength is 50N or more B: Break strength is less than 50N, 20N or more C: Break strength is less than 20N D: No thermocompression bonding

[3-7] Adhesiveness The copolymer composition (solution) was applied to a release film and dried by heating to prepare a sheet having a length of 3 cm, a width of 3 cm, and a thickness of 100 μm.
The sheet peeled from the release film was sandwiched between two glass plates (length 3 cm, width 5 cm), heated at 60 ° C. for 10 minutes with a hot plate, and the adhesion was evaluated based on the following evaluation criteria.
This evaluation test was conducted on the copolymers of Examples 2, 7, 15, 19 and Comparative Example 2.

(Adhesion evaluation criteria)
A: Can be bonded and the glass plate is fixed. B: Can be bonded, but peels off immediately.

<Examples 2 to 20>
Except that the type of polyvinyl acetal polymerizable compound used, the type and amount of (meth) acrylate used, and the amount ratio of polyvinyl acetal polymerizable compound to (meth) acrylate were as shown in Table 1. As in Example 1, a copolymer, a copolymer composition (solution), and a copolymer composition (paste) were prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2. The copolymers prepared in Examples 2 to 20 are shown as copolymer (2) to copolymer (20) in Tables 1 and 2, respectively.

<Comparative Example 1>
[1] Preparation of copolymer 12 parts of isobutyl methacrylate, 3 parts of 2-hydroxyethyl methacrylate, 35 parts of ethyl acetate and 0.15 part of azoisobutyronitrile (AIBN) as a polymerization initiator are added to a reaction vessel and mixed. Then, after sufficiently replacing the inside of the reaction vessel with nitrogen gas, a polymerization reaction was carried out at 70 ° C. for 8 hours. After completion of the polymerization reaction, the solvent was removed by drying under reduced pressure to obtain a solid state copolymer (C1) which is a (meth) acrylic copolymer. The weight average molecular weight by GPC of the copolymer (C1) was about 400,000 in terms of polystyrene (the same GPC conditions as in Example 1).
It was 59 degreeC when the glass transition temperature Tg of the copolymer (1) was measured.

[2] Preparation and Evaluation of Copolymer Composition Copolymer composition in the same manner as in Example 1 except that instead of copolymer (1), copolymer (C1) obtained above was used. A product (solution) and a copolymer composition (paste) were prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Comparative Example 2>
The copolymer composition (solution) and the copolymer weight were the same as in Example 1 except that polyvinyl butyral (“BH-S” manufactured by Sekisui Chemical Co., Ltd.) was used instead of the copolymer (1). A combined composition (paste) was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Comparative Example 3>
The copolymer composition (solution) and the copolymer weight were the same as in Example 1 except that polyvinyl butyral (“BM-S” manufactured by Sekisui Chemical Co., Ltd.) was used instead of the copolymer (1). A combined composition (paste) was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Comparative example 4>
Instead of the copolymer (1), the copolymer (C1) obtained in [1] of Comparative Example 1 and polyvinyl butyral (“BH-S” manufactured by Sekisui Chemical Co., Ltd.) 1: 1 ( (Mass ratio) A copolymer composition (solution) and a copolymer composition (paste) were prepared in the same manner as in Example 1 except that the mixture was used, and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Comparative Example 5>
Instead of the copolymer (1), 1: 1 (1) of the copolymer (C1) obtained in [1] of Comparative Example 1 and polyvinyl butyral (“BM-S” manufactured by Sekisui Chemical Co., Ltd.) (Mass ratio) A copolymer composition (solution) and a copolymer composition (paste) were prepared in the same manner as in Example 1 except that the mixture was used, and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Comparative Example 6>
Example 1 was used in the same manner as in Example 1 except that ethyl cellulose ("Etocel STD-100" manufactured by Dow Chemical Co., Ltd., number average molecular weight (standard polystyrene equivalent value by GPC): 63400) was used instead of copolymer (1). A copolymer composition (solution) and a copolymer composition (paste) were prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Comparative Example 7>
1: 1 (mass ratio) of the copolymer (C1) obtained in [1] of Comparative Example 1 and ethyl cellulose ("Etocel STD-100" manufactured by Dow Chemical Company) instead of the copolymer (1) ) A copolymer composition (solution) and a copolymer composition (paste) were prepared in the same manner as in Example 1 except that the mixture was used, and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Comparative Example 8>
[1] Preparation of copolymer A copolymer was prepared by a method according to the example of Patent Document 2. Specifically, it is as follows.
A solution was prepared by dissolving 100 parts of polyvinyl butyral (“BH-S” manufactured by Sekisui Chemical Co., Ltd.) in 400 parts of ethyl acetate.
0.5 parts of 2-isocyanatoethyl methacrylate (“Karenz MO-I” manufactured by Showa Denko) as an isocyanate group-containing vinyl monomer and 1 part by mass of triethylamine as a reaction catalyst are added to the resulting solution, and a reaction vessel is added. The reaction was carried out at 70 ° C. for 10 hours with stirring.
After completion of the reaction, a small sample was taken from the reaction mixture, dried, and subjected to ¹ H-NMR analysis. As a result, formation of a urethane bond could not be confirmed.
Subsequently, a polymerization reaction with isobutyl methacrylate and 2-hydroxyethyl methacrylate was performed under the same conditions as in Example 1 to obtain a resin component (D1).
A composition (solution) containing the resin component (D1) and a composition (paste) containing the resin component (D1) were prepared in the same manner as in Example 1 except that this resin component (D1) was used. Evaluation was performed in the same manner as in 1. The evaluation results are shown in Table 2.
As shown in Table 2, in this comparative example, phase separation was observed in the coating film, and the evaluation results were significantly inferior to those of the examples. This is presumably because the isocyanate group was decomposed by water contained in the polyvinyl butyral, and the vinyl group could not be introduced into the polyvinyl butyral, or the isocyanate group was inferior in reactivity.

Claims (4)

A structural unit (a) derived from a polyvinyl acetal polymerizable compound in which a polymerizable unsaturated group and / or a thiol group are bonded to polyvinyl acetal via an ester bond;
A structural unit (b) derived from (meth) acrylate;
A copolymer comprising   The copolymer according to claim 1, wherein the content ratio of the structural unit (a) and the structural unit (b) is in the range of 0.5: 9.5 to 9.5: 0.5 on a mass basis. .   A copolymer composition comprising the copolymer according to claim 1, inorganic particles, and an organic solvent.   The film molded object containing the copolymer of Claim 1 or 2.