JP2009161602A - Polyvinyl acetal composition containing modified polyvinyl acetate, polyvinyl acetal sheet comprised of the polyvinyl acetal composition, and interlayer film for laminated glass comprising the polyvinyl acetal composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyvinyl acetal composition that suffers from no optical strain and the like and exhibits excellent penetration resistance at low temperature when formed into a sheet, and a polyvinyl acetal sheet obtained by molding the polyvinyl acetal composition. <P>SOLUTION: The polyvinyl acetal composition includes at least polyvinyl acetal and a modified polyvinyl acetate having a carboxyl group in its side chain, where the modified polyvinyl acetate is contained in an amount of 0.1-50 pts.mass based on 100 pts.mass of the polyvinyl acetal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polyvinyl acetal composition. More specifically, the present invention relates to a polyvinyl acetal composition containing polyvinyl acetal and modified polyvinyl acetate.

  Polyvinyl acetal is a resin obtained by adding an aldehyde to polyvinyl alcohol to cause an acetalization reaction. Polyvinyl acetal is widely used as a raw material for interlayer films of laminated glass, paints, adhesives and the like.

  Among them, for example, in laminated glass using polyvinyl acetal as an intermediate film, even if flying objects such as stones collide and the glass breaks, the intermediate film interposed between the glasses absorbs the impact, and the flying objects Can be prevented. Moreover, since the glass bonded by the intermediate film remains adhered to the intermediate film even after breakage, it does not scatter. For this reason, it can prevent that a serious injury is added to a human body by using a laminated glass for the window of a transport organization, a building, etc.

  However, the interlayer film for laminated glass made of polyvinyl acetal has a problem that the performance of absorbing impact is lowered due to its elasticity being lowered at a low temperature of about 0 ° C. or less, thereby lowering the penetration resistance of the laminated glass. There was a point.

  As means for improving the penetration resistance of laminated glass, firstly, a technique of laminating a plurality of polyvinyl butyral sheets having different structures and different numbers of plasticizer parts is disclosed (Patent Documents 1 and 2). Second, a technique for improving penetration resistance by laminating a plurality of polyvinyl butyral sheets having different storage elastic moduli obtained by changing the degree of butyralization of polyvinyl butyral and the amount of plasticizer is disclosed ( Patent Document 3).

However, these techniques have a problem that an optical distortion due to the influence of the interface between the laminated polyvinyl acetal sheets is generated, and an image viewed through the laminated glass is distorted. In particular, the second technique has a problem that the penetration resistance at low temperatures is insufficient.
Japanese Patent Laid-Open No. 3-124440 JP-A-3-124441 JP 2004-123423 A

  Therefore, the present invention provides a polyvinyl acetal composition that does not cause optical distortion or the like when formed into a sheet and has excellent penetration resistance at low temperatures, and a polyvinyl acetal sheet formed by molding the polyvinyl acetal composition. The main purpose.

In order to solve the above problems, first, at least polyvinyl acetal and a modified polyvinyl acetate having a carboxyl group in a side chain are included, and the modified polyvinyl acetate is added in an amount of 0.1 to 100 parts by mass of the polyvinyl acetal. Provided is a polyvinyl acetal composition contained in 50 parts by mass. By including the amount of the modified polyvinyl acetate in the above range, optical distortion at the time of forming into a sheet can be suppressed, and penetration resistance at low temperatures can be improved.
The composition of the modified polyvinyl acetate is not particularly limited, but preferably contains 0.1 to 10 parts by mass of a carboxyl group with respect to 100 parts by mass of the vinyl acetate unit. By setting the composition of the modified polyvinyl acetate within the above range, the elastic force of the sheet at a low temperature is maintained. For this reason, when the obtained sheet | seat is used as an intermediate film of a laminated glass, the laminated glass excellent in penetration resistance can be obtained even in the environment below freezing point.
Moreover, this invention provides the polyvinyl acetal sheet formed by shape | molding the said polyvinyl acetal composition. By using the polyvinyl acetal composition, it is possible to obtain a sheet that suppresses optical distortion and has excellent penetration resistance at low temperatures.

  According to the polyvinyl acetal composition of the present invention, when it is formed into a sheet, optical distortion or the like does not occur, and penetration resistance at low temperatures can be improved.

  Hereinafter, preferred embodiments for carrying out the present invention will be described. The embodiment described below shows an example of the present invention, and the scope of the present invention is not interpreted narrowly.

  First, a preferred embodiment of the polyvinyl acetal composition according to the present invention will be described below.

  The polyvinyl acetal composition according to the present invention includes at least polyvinyl acetal and polyvinyl acetate having a carboxyl group in a side chain, and the modified polyvinyl acetate is 0.1 to 100 parts by mass of the polyvinyl acetal. 50 mass parts is contained, It is characterized by the above-mentioned.

  By containing the modified polyvinyl acetate in the above amount, when a sheet is formed into a laminated glass, the optical distortion is suppressed by reducing the difference in light refractive index from the glass, and low temperature (about −15 ° C.). ) To high temperatures (about 60 ° C.), the impact absorption characteristics can be improved. In addition, since it is not necessary to limit the composition of the polyvinyl acetal itself, it is possible to very easily suppress optical distortion and improve penetration resistance, and freely change the composition of the polyvinyl acetal according to the required physical properties. can do.

  The amount of the modified polyvinyl acetate added is not particularly limited as long as it is 0.1 to 50 parts by mass with respect to 100 parts by mass of polyvinyl acetal, but is preferably 0.5 to 20 parts by mass, and more preferably 1 It is desirable to be -8 mass parts. By making the addition amount of the modified polyvinyl acetate within the above range, the penetration resistance in the case of a laminated glass can be further improved. When the amount of the modified polyvinyl acetate added is less than 0.1 parts by mass, sufficient penetration resistance cannot be obtained when the sheet is formed into a sheet. On the other hand, when the amount of the modified polyvinyl acetate exceeds 50 parts by mass, the elastic modulus is lowered when the sheet is formed into a sheet, and the penetration resistance particularly in an environment of 50 ° C. or higher is deteriorated.

  The content of the carboxyl group in the modified polyvinyl acetate is not particularly limited, but is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the vinyl acetate unit. By making the content of the carboxyl group in the modified polyvinyl acetate within the above range, the obtained polyvinyl acetal sheet has excellent penetration resistance, but also when used for laminated glass as an interlayer film for laminated glass. This is desirable because optical distortion does not occur. The range of the content of carboxyl groups in the modified polyvinyl acetate is preferably 0.2 to 6 parts, more preferably 0.5 to 3 parts. By setting the content of the carboxyl group in the modified polyvinyl acetate within the above range, the penetration resistance when the laminated glass is formed can be further improved.

  The modified polyvinyl acetate is not particularly limited as long as it has a carboxyl group in the side chain. Specific examples include, for example, a copolymer of vinyl acetate and crotonic acid, a copolymer of vinyl acetate and itaconic acid, and the like. Can be mentioned. The polymerization degree of the modified polyvinyl acetate is not particularly limited, but preferably the polymerization degree is 300 to 6000. By setting the polymerization degree of the modified polyvinyl acetate within the above range, the melt viscosity when the polyvinyl acetal composition is formed into a sheet can be adjusted to an appropriate range. For this reason, an unnecessary shearing force and excessive thermal history are not applied to the polyvinyl acetal composition being molded, and a sheet in which the elastic force at a low temperature is maintained can be obtained. The obtained sheet has high transparency, and when this sheet is used as an interlayer film for laminated glass, a laminated glass having excellent penetration resistance in a wide range from low temperature to high temperature and further high transparency can be obtained. .

  Polyvinyl acetal is obtained by acetalizing a polyvinyl alcohol and an aldehyde in the presence of an acidic catalyst.

  The polyvinyl alcohol used for the synthesis of the polyvinyl acetal is not particularly limited, but the average degree of polymerization is preferably 300 to 3000, preferably 500 to 2500, and more preferably 1000 to 2000. The degree of saponification is preferably 80 mol% or more, and preferably 90 mol% or more. When the acetalization reaction is carried out by an aqueous medium method, the polyvinyl alcohol is preferably used as an aqueous solution of 3 to 15% by weight from the viewpoint of handling.

  By setting the polymerization degree and saponification degree of polyvinyl alcohol within the above ranges, the polymerization degree and composition of the obtained polyvinyl acetal can be adjusted, and the melt viscosity when the polyvinyl acetal composition is formed into a sheet is adjusted to an appropriate range. be able to. For this reason, an unnecessary shearing force and excessive thermal history are not applied to the polyvinyl acetal composition being molded, and a sheet in which the elastic force at a low temperature is maintained can be obtained. The obtained sheet has high transparency, and when this sheet is used as an interlayer film for laminated glass, a laminated glass having excellent penetration resistance in a wide range from low temperature to high temperature and further high transparency can be obtained. .

  The aldehyde used for the acetalization reaction is not particularly limited, and can be selected from various aldehydes according to the performance of the obtained polyvinyl acetal. Specifically, for example, formaldehyde, paraformaldehyde, acetaldehyde, paraacetaldehyde, propionaldehyde, butyraldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, 2-ethylhexylaldehyde, cyclohexylaldehyde, furfural, glyoxal, glutaraldehyde, benzaldehyde 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, β-phenylpropionaldehyde and the like. Preferably, butyraldehyde or acetaldehyde is used.

  The addition amount of the aldehyde is not particularly limited, and can be appropriately set according to the degree of acetalization of the target polyvinyl acetal.

  The acid catalyst is not particularly limited, and for example, inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as acetic acid and p-toluenesulfonic acid can be used. The amount of the acid catalyst to be added is not particularly limited, but generally an appropriate amount may be added so that the pH of the reaction solution is 0.3 to 2.0.

  The composition of the polyvinyl acetal used in the present invention is not particularly limited, but preferably contains 8 to 25% by mass of vinyl alcohol units and 0.1 to 15% by mass of fatty acid vinyl ester units. By setting the composition of the polyvinyl acetal within the above range, the sheet obtained from the polyvinyl acetal composition is excellent in strength and elastic modulus sufficient for shock absorption, adhesion to glass, transparency, and the like.

  The average degree of polymerization of the polyvinyl acetal is preferably 150 to 3500. By setting the average degree of polymerization of the polyvinyl acetal within the above range, the melt viscosity can be adjusted to an appropriate range when the polyvinyl acetal composition is formed into a sheet. Moreover, the obtained sheet | seat has intensity | strength and elastic modulus sufficient for shock absorption, and adhesiveness with glass.

  The polyvinyl acetal composition according to the present invention only needs to contain at least the polyvinyl acetal and the modified polyvinyl acetate, and if necessary, one or more kinds of various additives may be added. it can.

  Next, preferred embodiments of the polyvinyl acetal sheet according to the present invention will be described below.

  The polyvinyl acetal sheet can be obtained by mixing a polyvinyl acetal composition according to the present invention with a plasticizer, kneading, melting and forming into a sheet shape.

The plasticizer is not particularly limited, and those usually used as plasticizers for plastics can be used. It is preferable to use an ester plasticizer having an ether bond in the molecule.
Specific examples of the ester plasticizer include, for example, ethylene glycol-di-2-ethyl butyrate, 1,3-propylene glycol-2-ethyl butyrate, 1,4-propylene glycol-2-ethyl butyrate, 1, 2-propylene glycol-2-ethylbutyrate, diethylene glycol-2-ethylbutyrate, diethylene glycol-2-ethylhexoate, triethyleneglycol-2-ethylbutyrate, triethyleneglycol-2-ethylhexoate, tetra And ethylene glycol-2-ethylbutyrate.

  The amount of the plasticizer added to the polyvinyl acetal composition is not particularly limited, and can be appropriately adjusted depending on the average degree of polymerization, the degree of acetalization, the amount of residual acetyl groups, etc. of the polyvinyl acetal. Preferably, the plasticizer should be about 10 to 50 parts by mass with respect to 100 parts by mass of the polyvinyl acetal. By adding an amount of the plasticizer within the above range, a polyvinyl acetal sheet having excellent penetration resistance can be obtained while maintaining melt moldability. The plasticizers can be used alone or in combination of two or more.

  When mixing and kneading and melting a plasticizer in a polyvinyl acetal composition, an ultraviolet absorber, an antioxidant, an adhesive force regulator, a coupling agent, a surfactant, a heat stabilizer, and an infrared absorber as necessary. Various additives such as a fluorescent agent, a colorant, a dehydrating agent, an antifoaming agent, an antistatic agent, and a flame retardant may be added.

As the ultraviolet absorber, those usually used for plastics can be used. For example, a benzotriazole ultraviolet absorber, a hindered amine ultraviolet absorber, a benzoate ultraviolet absorber, or the like can be used.
Specific examples of the benzotriazole ultraviolet absorber include, for example, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α′dimethylbenzyl) phenyl]. -2H-benzotriazole, 2- (3,5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzo Triazole, 2- (3,5-di-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-tert-amyl-2-hydroxyphenyl) benzo Triazole, 2- (2′-hydroxy-5′-t-octylphenyl) benzotriazole and the like can be mentioned.
Specific examples of hindered amine ultraviolet absorbers include, for example, 2,2,6,6-tetramethyl-4-piperidylbenzoate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1 , 2,2,6,6-pentamethyl-4-piperidyl) -2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate, 4- (3- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionyloxy) -1- (2- (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl) -2, 2,6,6-tetramethylpiperidine and the like can be mentioned.
Specific examples of the benzoate ultraviolet absorber include, for example, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, hexadecyl-3,5-di-t-butyl- 4-hydroxybenzoate etc. are mentioned.

  Although the addition amount of a ultraviolet absorber is not specifically limited, It is desirable to set it as the range of 10-100,000 ppm on the basis of weight with respect to a polyvinyl acetal composition, Preferably it is 100-10000 ppm. By adding the ultraviolet absorber in an amount within the above range, the light resistance of the obtained sheet can be improved while suppressing the production cost. An ultraviolet absorber can be used individually or in combination of 2 or more types.

  The antioxidant is not particularly limited, and for example, a phenol-based antioxidant, a phosphorus-based antioxidant, a sulfur-based antioxidant, and the like can be used. A phenolic antioxidant is preferable, and an alkyl-substituted phenolic antioxidant is more preferable.

As the phenolic antioxidant, an alkyl-substituted phenolic compound, an acrylate compound, a triazine group-containing phenolic compound, or the like can be used.
Specific examples of the alkyl-substituted phenol compound include, for example, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, octadecyl-3- (3,5 -) Di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylene-bis (4-methyl-6-t-butylphenol), 4,4'-butylidene-bis (4-methyl-6-) t-butylphenol), 4,4′-butylidene-bis (6-t-butyl-m-cresol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), bis (3-cyclohexyl-2) -Hydroxy-5-methylphenyl) methane, 3,9-bis (2- (3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy) -1,1-dimethyl Ruethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3, 5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3 ′, 5′-di-t-butyl-4 ′) -Hydroxyphenyl) propionate) methane, triethylene glycol bis (3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate) and the like.
Specific examples of the acrylate compound include, for example, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2,4-di-t-amyl. -6- (1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate and the like.
Specific examples of the triazine group-containing phenol compound include 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bis-octylthio-1,3,5-triazine, 6- (4- Hydroxy-3,5-dimethylanilino) -2,4-bis-octylthio-1,3,5-triazine, 6- (4-hydroxy-3-methyl-5-t-butylanilino) -2,4-bis -Octylthio-1,3,5-triazine, 2-octylthio-4,6-bis- (3,5-di-t-butyl-4-oxyanilino) -1,3,5-triazine and the like.

As a phosphorus antioxidant, a monophosphite compound and a diphosphite compound can be used. A monophosphite compound is preferably used.
Specific examples of monophosphite compounds include, for example, triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2-t -Butyl-4-methylphenyl) phosphite, tris (cyclohexylphenyl) phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octylphosphite, 9,10-dihydro-9-oxa- 10-phosphaphenanthrene-10-oxide, 10- (3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10 -Decyloxy-9,10-dihydro-9-oxa 10 phospha-phenanthrene, and the like.
Specific examples of diphosphite compounds include, for example, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl phosphite), 4,4′-isopropylidene-bis (phenyl- Di-alkyl (C12-C15) phosphite), 4,4′-isopropylidene-bis (diphenylmonoalkyl (C12-C15) phosphite), 1,1,3-tris (2-methyl-4-di-) Examples include tridecyl phosphite-5-tert-butylphenyl) butane, tetrakis (2,4-di-tert-butylphenyl) -4,4′-biphenylene phosphite.

  Specific examples of the sulfur-based antioxidant include, for example, dilauryl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, lauryl stearyl 3,3′-thiodipropionate, pentaerythritol- Examples include tetrakis- (β-lauryl-thiopropionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane.

  Although the addition amount of antioxidant is not specifically limited, It is desirable to set it as 0.001-5 weight part with respect to 100 weight part of polyvinyl acetal compositions, Preferably 0.01-1 weight part. By adding an amount of the antioxidant in the above range, it is possible to prevent thermal degradation during melt molding and oxidation degradation due to contact with the outside air. Antioxidants can be used alone or in combination of two or more.

  The adhesive strength modifier is not particularly limited, and examples thereof include alkali metal salts or alkaline earth metal salts of organic acids, alkali metal salts or alkaline earth metal salts of inorganic acids, and modified silicone oils. Specific examples of the organic acid include carboxylic acids such as octylic acid, hexyl acid, butyric acid, acetic acid, formic acid, and the like. Specific examples of the inorganic acid include hydrochloric acid and nitric acid.

  Specific examples of the alkali metal salt or alkaline earth metal salt of the organic acid and the alkali metal salt or alkaline earth metal salt of the inorganic acid include, for example, potassium salts, sodium salts, magnesium salts of various organic acids and inorganic acids, etc. Is mentioned.

  The alkali metal salt or alkaline earth metal salt of the organic acid and the alkali metal salt or alkaline earth metal salt of the inorganic acid are not particularly limited, but preferably an alkali metal salt of an organic acid having 2 to 16 carbon atoms or It is desirable to use an alkaline earth metal salt. More preferably, it is desirable to use a potassium salt or magnesium salt of a carboxylic acid having 2 to 16 carbon atoms.

  Specific examples of the alkali metal salt or alkaline earth metal salt of a carboxylic acid having 2 to 16 carbon atoms include, for example, potassium acetate, magnesium acetate, potassium propionate, magnesium propionate, potassium 2-ethylbutanoate, and 2-ethylbutanoate magnesium. Examples include potassium 2-ethylhexylate, magnesium 2-ethylhexylate, and the like.

  The addition amount of the alkali metal salt or alkaline earth metal salt of the organic acid and the alkali metal salt or alkaline earth metal salt of the inorganic acid is not particularly limited, but is 0.0001 per 100 parts by weight of the polyvinyl acetal composition. To 1 part by weight, preferably 0.001 to 0.5 part by weight, more preferably 0.01 to 0.2 part by weight. By adding the alkali metal salt or alkaline earth metal salt of the organic acid and the alkali metal salt or alkaline earth metal salt of the inorganic acid in the above range, a polyvinyl acetal sheet is obtained without impairing the transparency of the laminated glass. The adhesiveness of can be adjusted. The alkali metal salt or alkaline earth metal salt of the organic acid and the alkali metal salt or alkaline earth metal salt of the inorganic acid may be used alone or in combination of two or more.

  The modified silicone oil is not particularly limited as long as it is generally obtained by reacting a compound to be modified with polysiloxane. Specific examples include epoxy-modified silicone oil, ether-modified silicone oil, ester-modified silicone oil, amine-modified silicone oil, carboxyl-modified silicone oil and the like.

  The molecular weight of the modified silicone oil is not particularly limited, but it is desirable that the molecular weight is 800 to 5000, preferably 1500 to 4000. By setting the molecular weight of the modified silicone oil in the above range, the compatibility with the polyvinyl acetal composition according to the present invention can be maintained and dispersed uniformly in the polyvinyl acetal.

  Although the addition amount of the modified silicone oil is not particularly limited, it is 0.01 to 0.2 parts by weight, preferably 0.03 to 0.1 parts by weight with respect to 100 parts by weight of the polyvinyl acetal composition. desirable. By adding the modified silicone oil in an amount within the above range, the adhesive force of the polyvinyl acetal sheet can be adjusted while maintaining good compatibility with the polyvinyl acetal composition according to the present invention. The said modified silicone oil may be used independently and may use 2 or more types together.

    The polyvinyl acetal composition according to the present invention can be molded into a sheet to form a polyvinyl acetal sheet.

The polyvinyl acetal sheet according to the present invention is not particularly limited, but it is preferable that the breaking strength when measured at a tensile speed of 500 mm / min in accordance with JIS K 7161 is 25 MPa or more. By setting the breaking strength of the polyvinyl acetal sheet within the above range, a sufficient strength can be obtained when used as an interlayer film for laminated glass.
A more preferable range of the breaking strength of the polyvinyl acetal sheet is 30 to 50 MPa. Since it becomes suitable intensity | strength and toughness by setting it as this range, when it is set as a laminated glass, the stress by an impact is disperse | distributed to the whole glass surface, without concentrating in the narrow range. The penetration resistance of laminated glass is even higher.

  The method for producing the polyvinyl acetal sheet according to the present invention is not particularly limited, and can be produced by a known molding method. Specifically, for example, the polyvinyl acetal composition can be formed into a sheet by extrusion molding, press molding, blow molding, injection molding, or the like. In particular, a method in which a polyvinyl acetal composition, a plasticizer, and other additives are supplied to an extruder, kneaded and melted, taken out from a T die, taken out by a take-up machine, and formed into a sheet shape is preferable.

  The thickness of the polyvinyl acetal sheet is not particularly limited, but is preferably 0.2 to 1.5 mm. In addition, a plurality of polyvinyl acetal sheets having the same composition may be laminated or polyvinyl acetal sheets having other compositions may be laminated in accordance with purposes such as strength improvement, sound insulation, heat insulation, light shielding, and decoration. When laminating a polyvinyl acetal sheet, by laminating the polyvinyl acetal sheet according to the present invention on the outermost layer side, for example, when stored in a rolled state, the front and back are bonded and integrated. (Hereinafter referred to as “self-attachment”).

  Self-adhesion can be further suppressed by embossing the surface of the polyvinyl acetal sheet. Further, when used as an interlayer film for laminated glass, air can be expelled through the unevenness of the embossed pattern to prevent bubbles from remaining between the glass and the interlayer film. The depth and shape of the emboss are not particularly limited.

  Moreover, the polyvinyl acetal composition according to the present invention is formed into a sheet shape and suitably used as an interlayer film for laminated glass.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples.

  Each characteristic was evaluated by the method shown below.

<Measurement of breaking strength of polyvinyl acetal sheet>
The breaking strength of the polyvinyl acetal sheet was measured according to JIS K 7161 at a tensile speed of 500 mm / min.

<Measurement method of saponification degree of polyvinyl alcohol>
The measurement was performed according to the method described in JIS K 6726.

<Measurement method of average polymerization degree of polyvinyl alcohol>
The measurement was performed according to the method described in JIS K 6726.

<Measurement method of average degree of polymerization of polyvinyl acetal>
The measurement was performed according to the method described in JIS K 6728 (old standard).

<Measurement method of vinyl alcohol unit of polyvinyl acetal>
The measurement was performed according to the method described in JIS K 6728 (old standard).

<Measurement method of fatty acid vinyl ester unit of polyvinyl acetal>
The measurement was performed according to the method described in JIS K 6728 (old standard).

<Measurement method of average polymerization degree of polyvinyl acetate>
The measurement was performed according to the method described in JIS K 6728 (old standard).

<Measurement method of carboxyl group content of polyvinyl acetate>
The content of carboxyl groups in the polyvinyl acetate was such that 1% by weight of polyvinyl acetate solution was prepared by adding polyvinyl acetate to a solvent adjusted to methanol: water = 4: 1 (volume ratio). This was calculated by titrating with 0.1 mol / L sodium hydroxide aqueous solution using phenolphthalein as an indicator.

<Production of laminated glass>
A polyvinyl acetal sheet was sandwiched between two pieces of float glass having a thickness of 3 mm and pre-pressed by a roll method. Subsequently, it pressure-bonded for 30 minutes with the pressure of 12 kg / cm < ² > with the 140 degreeC autoclave, and the transparent laminated glass was obtained.

<Evaluation of penetration resistance of laminated glass>
The penetration resistance performance of the laminated glass was evaluated for three types of laminated glass with different storage temperatures in accordance with JIS R 3212. A steel ball with a mass of 2260 ± 20 g and a diameter of about 82 mm is dropped onto the center of the sample by changing the height onto a laminated glass sample of about 300 × 300 mm stored at −10 ° C., 25 ° C. and 55 ° C. for 4 hours or more, respectively. I let you. The test was repeated while increasing the drop height of the steel ball, and the maximum height at which the number of times of penetration corresponding to 50% of the number of tests in the same height test was hindered was obtained, and was defined as penetration resistance.

<Evaluation of optical distortion of laminated glass>
The presence or absence of optical distortion of the image through the laminated glass was evaluated.

<Example 1>
(Synthesis of polyvinyl acetal)
100 g of polyvinyl alcohol having a saponification degree of 98 mol% and an average polymerization degree of 1700 was dissolved in distilled water to obtain a polyvinyl alcohol aqueous solution having a concentration of 10% by mass. While stirring this aqueous solution at 40 ° C. with an anchor type stirring blade, 32 g of 35 mass% hydrochloric acid was added, and then 60 g of butyraldehyde was added dropwise. After the polyvinyl acetal was precipitated in the aqueous solution, the reaction was completed by heating to 50 ° C. and stirring for 4 hours while adding 64 g of 35% by mass hydrochloric acid to obtain a polyvinyl acetal dispersion. The obtained dispersion is cooled, neutralized to a pH of 7.5 with 30% by mass aqueous sodium hydroxide solution, filtered, washed with distilled water of 20 times the amount of polymer and dried to obtain polyvinyl acetal. Obtained.

(Preparation of polyvinyl acetal composition)
6 parts by mass of a vinyl acetate / crotonic acid copolymer (degree of polymerization 2000) having a carboxyl group content of 4 parts by mass with respect to 100 parts by mass of vinyl acetate units with respect to 100 parts by mass of the obtained polyvinyl acetal. And a polyvinyl acetal composition was obtained.

(Preparation of polyvinyl acetal sheet)
Under the production conditions shown in Table 1, a polyvinyl acetal sheet having a thickness of 0.76 mm was obtained.
Triethylene glycol di-2-ethylhexanoate was used as the plasticizer, and the amount was 40 parts by mass with respect to 100 parts by mass of the polyvinyl acetal composition.

<Examples 2 and 3>
A polyvinyl acetal sheet was produced under the same conditions as in Example 1 except that the amount of the modified polyvinyl acetate added was 0.1 parts by mass (Example 2) and 50 parts by mass (Example 3).

<Examples 4 to 7>
Polyvinyl acetate was modified under the same conditions as in Example 1 except that the polymerization degree of the modified polyvinyl acetate was 200 (Example 4), 300 (Example 5), 6000 (Example 6), and 7000 (Example 7). An acetal sheet was prepared.

<Examples 8 to 14>
The carboxyl group content of the modified polyvinyl acetate is 0.01 parts by mass (Example 8), 0.1 parts by mass (Example 9), 0.2 parts by mass (Example 10), 0.5 parts by mass (implementation). Example 11) A polyvinyl acetal sheet was produced under the same conditions as in Example 1 except that 3 parts by mass (Example 12), 10 parts by mass (Example 13), and 12 parts by mass (Example 14) were used. .

<Examples 15 to 20>
The average degree of polymerization of the polyvinyl acetal was 100 (Example 15), 300 (Example 16), 500 (Example 17), 2500 (Example 18), 3500 (Example 19), and 4000 (Example 20). A polyvinyl acetal sheet was produced under the same conditions as in Example 1 except for the points.

<Comparative Examples 1 and 2>
A polyvinyl acetal sheet was produced under the same conditions as in Example 1 except that the addition amount of polyvinyl acetate was 0.01 parts by mass (Comparative Example 1) and 52 parts by mass (Comparative Example 2).

  Tables 2 to 5 show the penetration resistance evaluation results and optical distortion evaluation results of the laminated glasses of the examples and comparative examples.

<Discussion>
In Examples 1 to 20, the adhesiveness of the sheet and the penetration resistance of the laminated glass at each temperature were good, and the target of the present invention could be achieved.

Claims (4)

At least a polyvinyl acetal and a modified polyvinyl acetate having a carboxyl group in the side chain,
The modified polyvinyl acetate is a polyvinyl acetal composition containing 0.1 to 50 parts by mass with respect to 100 parts by mass of the polyvinyl acetal.   The polyvinyl acetal composition according to claim 1, wherein the modified polyvinyl acetate contains 0.1 to 10 parts by mass of a carboxyl group with respect to 100 parts by mass of the vinyl acetate unit.   A polyvinyl acetal sheet obtained by molding the polyvinyl acetal composition according to claim 1 or 2 into a sheet shape. An interlayer film for laminated glass obtained by molding the polyvinyl acetal composition according to claim 1 or 2 into a sheet shape.