JP2013023598A - Acrylic thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic thermoplastic resin composition which holds the characteristics of methacrylic thermoplastic resin, such as transparency, high surface hardness, high stiffness, weather resistance and heat resistance, has good toughness, and can suitably be used in uses needing stable moldability, high heat resistance, high heat stability and high quality.SOLUTION: The acrylic thermoplastic resin composition comprises a methacrylic resin (A) and a polyvinyl acetal resin (B) obtained by acetalizing a polyvinyl alcohol resin having a viscosity-average polymerization degree of 500-2,000 and a saponification degree of ≥99.5 mol% at an acetalization degree of 65-88 mol%.

Description

  The present invention relates to an acrylic thermoplastic resin composition. More specifically, the present invention retains the features of methacrylic resins such as high transparency, high surface hardness, high rigidity, excellent weather resistance, heat resistance, etc., and has good toughness, stable moldability, high The present invention relates to an acrylic thermoplastic resin composition that can be suitably used in applications that require heat resistance, high thermal stability, and high-quality molded products.

  A methacrylic resin obtained by polymerizing a monomer mainly containing methyl methacrylate has features such as high total light transmittance in the visible light region and high surface hardness. While methacrylic resins are used in various fields, impact resistance and toughness are slightly low, and improvements are required. Furthermore, improvements in heat resistance, thermal stability and moldability at high temperatures are also demanded.

  As a response to such a requirement, Patent Document 1 discloses an acrylic thermoplastic resin composition comprising a methacrylic resin and a polyvinyl acetal resin. This acrylic thermoplastic resin composition has high transparency, excellent surface hardness, and good impact resistance and toughness. However, for the reasons described below, there are difficulties in melt moldability at high temperatures.

  The polyvinyl acetal resin is produced by acetalizing a polyvinyl alcohol resin with an aldehyde. Polyvinyl acetal resins are used in a wide range of fields such as interlayer films for automobile windshields and safety glass, various binders, and adhesives. The polyvinyl acetal resin itself is not suitable for melt molding at a high temperature because it does not have sufficient thermal stability and undergoes thermal decomposition or thermal degradation at a high temperature to cause generation of decomposition gas or generation of a crosslinked gel.

In order to improve the melt moldability of the polyvinyl acetal resin at a high temperature, it is generally performed to add a plasticizer to the polyvinyl acetal resin (Patent Documents 2 to 4). However, the addition of a plasticizer may reduce the strength, elastic modulus and surface hardness of the molded product. Further, the plasticizer may gradually bleed out from the molded product.
Patent Document 5 discloses a polyvinyl acetal resin obtained by blending poly (ε-caprolactone) instead of a plasticizer as a raw material for an interlayer film for laminated glass. The blending of poly (ε-caprolactone) improves moldability. However, since poly (ε-caprolactone) has a low melting point and low heat resistance, the range of use is limited. In addition, a resin molded product obtained by blending poly (ε-caprolactone) has a low surface hardness.

  In addition, the addition of various additives such as antioxidants, stabilizers, UV absorbers, lubricants and processing aids has been studied, but it has led to fundamental improvements in the thermal stability of polyvinyl acetal resins. Not in.

JP 2008-133352 A JP 2001-206741 A JP 2001-226152 A JP 2008-105942 A JP-A-7-17745

  The object of the present invention is to retain the features of methacrylic resins such as high transparency, high surface hardness, high rigidity, excellent weather resistance, heat resistance, etc., and have good toughness, stable moldability, high heat resistance Another object of the present invention is to provide an acrylic thermoplastic resin composition that can be suitably used even in applications that require high thermal stability and high quality.

Factors that affect the thermal stability of the polyvinyl acetal resin include the degree of polymerization of the polyvinyl alcohol resin as a raw material, the degree of saponification, the modified species and the amount of modification, the acetal species and the degree of acetalization of the polyvinyl acetal resin, and further in the resin Residual metal residues, unreacted aldehydes, by-products, and the like are considered. These factors are intertwined in a complicated manner, and it is considered that thermal deterioration such as decomposition, cross-linking gelation, and coloring occurs. However, since it is not clearly understood by what mechanism the thermal degradation proceeds for these factors, a polyvinyl acetal resin having sufficient thermal stability cannot be obtained. It was also impossible to obtain a composition having excellent thermal stability using a resin.
As a result of intensive studies to solve the above-mentioned problems, the present inventors obtained a polyvinyl alcohol resin having a polymerization degree within a specific range and a very high saponification degree by acetalizing at a specific acetalization degree. It has been found that a resin composition obtained by blending a polyvinyl acetal resin with a methacrylic resin is excellent in thermal stability at high temperatures and has good moldability. The present invention has been completed by further studies based on this finding.

That is, the present invention includes the following.
[1] Methacrylic resin (A);
Acrylic containing a polyvinyl acetal resin (B) obtained by acetalizing a polyvinyl alcohol resin having a viscosity average polymerization degree of 500 to 2000 and a saponification degree of 99.5 mol% or more at an acetalization degree of 65 to 88 mol% -Based thermoplastic resin composition.
[2] The acrylic thermoplastic resin composition according to [1], which contains 20 parts by mass or less of a plasticizer with respect to 100 parts by mass of the polyvinyl acetal resin (B).
[3] The acrylic thermoplastic resin composition according to [1] or [2], wherein the polyvinyl acetal resin (B) does not contain a plasticizer.
[4] The polyvinyl acetal resin (B) is obtained by acetalizing a polyvinyl alcohol resin and adjusting the pH of the obtained slurry to 6 to 8, followed by drying treatment, [1] to [ 3] The acrylic thermoplastic resin composition according to any one of 3).

[5] The acrylic thermoplastic resin composition according to any one of [1] to [4], wherein the polyvinyl acetal resin (B) is adjusted to a moisture content of 0.005 to 2%.
[6] The polyvinyl acetal resin (B) is a resin obtained by acetalization with an aldehyde having 4 or more carbon atoms and an aldehyde having 3 or less carbon atoms,
The total amount of vinyl alcohol units acetalized with aldehyde is 65 to 88 mol% of all repeating units, and acetalized with vinyl alcohol units acetalized with aldehydes having 4 or more carbon atoms / aldehydes with 3 or less carbon atoms. The acrylic thermoplastic resin composition according to any one of [1] to [5], wherein the molar ratio of vinyl alcohol units is 90/10 to 0/100.
[7] The mass ratio (A) / (B) between the methacrylic resin (A) and the polyvinyl acetal resin (B) is 99/1 to 51/49, and any one of [1] to [6] Acrylic thermoplastic resin composition.

[8] A molded article comprising the acrylic thermoplastic resin composition according to any one of [1] to [7].
[9] A film comprising the acrylic thermoplastic resin composition according to any one of [1] to [7].
[10] A method for producing a molded article comprising heat-molding the acrylic thermoplastic resin composition according to any one of [1] to [7].
[11] A method for producing a film comprising heat-molding the acrylic thermoplastic resin composition according to any one of [1] to [7].

  The acrylic thermoplastic resin composition of the present invention contains a polyvinyl acetal resin and a methacrylic resin, has high transparency, high surface hardness, high rigidity, toughness, surface smoothness, weather resistance, heat resistance and It has features such as excellent thermal stability. According to the acrylic thermoplastic resin composition of the present invention, a high-quality molded product can be stably obtained by a melt molding method or the like.

  The acrylic thermoplastic resin composition of the present invention contains a methacrylic resin (A) and a polyvinyl acetal resin (B).

  The methacrylic resin (A) used in the present invention is obtained by polymerizing a monomer mixture containing a methacrylic acid ester (alkyl methacrylate).

  Methacrylic acid esters include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, Examples include myristyl methacrylate, palmityl methacrylate, stearyl methacrylate, behenyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, and phenyl methacrylate. The methallylic acid ester may be used alone or in combination of two or more. Of these, alkyl methacrylates having 1 to 4 carbon atoms in the alkyl group are preferred, and methyl methacrylate is particularly preferred.

In addition to the methacrylic acid ester, the monomer mixture may contain an acrylic acid ester.
As acrylic esters, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, s-butyl acrylate, t-butyl acrylate, pentyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, Examples include myristyl acrylate, palmityl acrylate, stearyl acrylate, behenyl acrylate, cyclohexyl acrylate, benzyl acrylate, and phenyl acrylate. Acrylic esters may be used alone or in combination of two or more. Of these, alkyl acrylates having 1 to 8 carbon atoms in the alkyl group are preferred.

The monomer mixture may contain other ethylenically unsaturated monomers copolymerizable with methacrylic acid esters and acrylic acid esters.
Examples of the ethylenically unsaturated monomer include diene compounds such as 1,3-butadiene and isoprene; styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, styrene nucleus-substituted with halogen, 1 -Vinyl aromatic compounds such as vinylnaphthalene, 4-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene; acrylonitrile, methacrylate Examples thereof include ethylenically unsaturated nitrile compounds such as nitrile; acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, maleic anhydride, maleic imide, monomethyl maleate, dimethyl maleate and the like. You may use an ethylenically unsaturated monomer individually by 1 type or in combination of 2 or more types.

  In the methacrylic resin (A) used in the present invention, the proportion of methacrylic acid ester units is preferably 50 to 100% by mass and more preferably 80 to 99.9% by mass from the viewpoint of weather resistance. preferable. Moreover, it is preferable to contain an acrylate ester unit in the range of 0.1-20 mass% from a heat resistant viewpoint.

The methacrylic resin (A) used in the present invention preferably has a weight average molecular weight (hereinafter sometimes referred to as Mw) from the viewpoint of strength characteristics and meltability, preferably 40,000 or more, more preferably 40. 1,000 to 10,000,000, particularly preferably 80,000 to 1,000,000.
The methacrylic resin (A) used in the present invention may be one in which monomers are linearly connected and bonded, one having a branch, or one having a cyclic structure. May be.

  The production method of the methacrylic resin (A) used in the present invention is not particularly limited as long as it is a method capable of polymerizing an ethylenically unsaturated compound. The methacrylic resin (A) used in the present invention is preferably produced by radical polymerization. Examples of the polymerization method include bulk polymerization, suspension polymerization, solution polymerization, and emulsion polymerization.

  Examples of radical polymerization initiators used in the polymerization include azo compounds such as azobisisobutyronitrile and azobisγ-dimethylvaleronitrile; benzoyl peroxide, cumyl peroxide, oxyneodecanoate, diisopropyl peroxydicarbonate, t Examples thereof include peroxides such as -butyl cumyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, and lauroyl peroxide. The polymerization initiator is preferably used in an amount of 0.05 to 0.5 parts by mass with respect to 100 parts by mass of all monomers. The temperature during the polymerization is preferably 50 to 140 ° C., and the polymerization time is preferably 2 to 20 hours.

  In order to control the molecular weight of the methacrylic resin (A), a chain transfer agent can be used. Examples of chain transfer agents include methyl mercaptan, ethyl mercaptan, isopropyl mercaptan, n-butyl mercaptan, t-butyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, ethylthioglycoate, mercaptoethanol, thio- β-naphthol, thiophenol and the like can be mentioned. The chain transfer agent is preferably used in an amount of 0.005 to 0.5 parts by mass with respect to 100 parts by mass of the total monomers.

The polyvinyl acetal resin (B) used in the present invention has a vinyl alcohol unit (formula (I)), a vinyl ester unit (formula (II)) and a vinyl acetal unit (two vinyl alcohol units acetalized with aldehydes). Material: A resin having the formula (III)). In the following formula, l is a molar ratio of vinyl alcohol units, m is a molar ratio of vinyl ester units, k / 2 is a molar ratio of vinyl acetal units, and k is a vinyl alcohol acetalized with an aldehyde. the molar ratio of the units, R ^a is R ^a in the aldehyde used for acetalization (R ^a -CHO). R ^b is R ^b in the vinyl ester _{^{(R b COOCH = CH 2)}} . However, l and / or m may be zero. In the polyvinyl acetal resin (B) consisting only of the vinyl alcohol unit, the vinyl ester unit and the vinyl acetal unit, k + 1 + m = 1. Each unit is not particularly limited by the arrangement order, and may be arranged at random, in a block shape, or in a tapered shape. Further, the bond between the repeating units may be Head-to-Tail or Head-to-Head.

  The polyvinyl acetal resin (B) used in the present invention can be obtained, for example, by acetalizing a polyvinyl alcohol resin (hereinafter sometimes referred to as PVA) with an aldehyde.

  The polyvinyl alcohol resin may be a homopolymer composed only of vinyl alcohol units, or a copolymer composed of vinyl alcohol and a monomer copolymerizable therewith (hereinafter sometimes referred to as PVA copolymer). May be. Furthermore, it may be a modified polyvinyl alcohol resin having a functional group such as a carboxyl group introduced in the middle, end, or side chain of the molecular chain. These polyvinyl alcohol resins may be used alone or in combination of two or more.

  A polyvinyl alcohol resin is not specifically limited by the manufacturing method, For example, what is obtained by saponifying vinyl ester-type polymers, such as polyvinyl acetate, can be used. Examples of vinyl ester monomers for forming vinyl ester units include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, Examples include vinyl versatate. Among these, vinyl acetate is preferable in that PVA can be obtained with good productivity.

  Examples of the copolymerizable monomer constituting the PVA copolymer include α-olefins such as ethylene, propylene, 1-butene, isobutene and 1-hexene; acrylic acid and salts thereof; methyl acrylate, ethyl acrylate, acrylic Acrylic acid esters such as n-propyl acid and i-propyl acrylate; methacrylic acid and salts thereof; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate and i-propyl methacrylate; acrylamide Acrylamide derivatives such as N-methylacrylamide and N-ethylacrylamide; methacrylamide derivatives such as methacrylamide, N-methylmethacrylamide and N-ethylmethacrylamide; methyl vinyl ether, ethyl vinyl ether, -Vinyl ethers such as propyl vinyl ether, i-propyl vinyl ether and n-butyl vinyl ether; Hydroxy group-containing vinyl ethers such as ethylene glycol vinyl ether, 1,3-propanediol vinyl ether and 1,4-butanediol vinyl ether; allyl acetate, propyl Allyl ethers such as allyl ether, butyl allyl ether and hexyl allyl ether; monomers having an oxyalkylene group such as polyoxyethylene group, polyoxypropylene group and polyoxybutylene group; vinyl silanes such as vinyltrimethoxysilane; Isopropenyl acetate, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, 7-octen-1-ol, 9-decene-1-ol, 3- Hydroxyl-containing α-olefins such as methyl-3-buten-1-ol or esterified products thereof; N-vinylamides such as N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone; fumaric acid, maleic acid , Monomers having a carboxyl group derived from itaconic acid, maleic anhydride, phthalic anhydride, trimellitic anhydride or itaconic anhydride; ethylenesulfonic acid, allylsulfonic acid, methallylsulfonic acid, 2-acrylamide-2 A monomer having a sulfonic acid group derived from methylpropanesulfonic acid, etc .; vinyloxyethyltrimethylammonium chloride, vinyloxybutyltrimethylammonium chloride, vinyloxyethyldimethylamine, vinyloxymethyldiethylamine, N-acrylamid Trimethylammonium chloride, N- acrylamide trimethyl ammonium chloride, N- acrylamide dimethylamine, allyl trimethyl ammonium chloride, methallyl trimethylammonium chloride, dimethyl allyl amine include monomers having a cationic group such as from allyl ethylamine.

  The content of these copolymerizable monomer units (hereinafter sometimes referred to as comonomer units) is preferably 20 mol% in 100 mol% of all monomer units constituting the PVA copolymer. Below, more preferably 10 mol% or less. Moreover, in order to exhibit the merit of being copolymerized, it is preferable that 0.01 mol% or more is a comonomer unit.

  Examples of the polymerization method used in the production of the vinyl ester polymer include known methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. Among these, the bulk polymerization method and the solution polymerization method, which are methods of polymerization in the absence of solvent or in a solvent such as alcohol, are preferable. As alcohol used as a solvent in the solution polymerization method, lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol are usually used. Examples of the polymerization initiator include azo compounds such as α, α′-azobisisobutyronitrile and 2,2′-azobis (2,4-dimethyl-valeronitrile), benzoyl peroxide, and n-propyl peroxycarbonate. And peroxides. Although there is no restriction | limiting in particular about superposition | polymerization temperature, Usually, it is 0 to 200 degreeC.

In the saponification of the vinyl ester polymer, an alkaline substance is usually used as a catalyst. Examples of the alkaline substance include potassium hydroxide and sodium hydroxide. The molar ratio of the alkaline substance used for the saponification catalyst is preferably 0.004 to 0.5, more preferably 0.005 to 0.05, with respect to the vinyl ester unit in the vinyl ester polymer. The alkaline substance as a saponification catalyst may be added all at the beginning of the saponification reaction, or may be additionally added during the saponification reaction.
Examples of the solvent that can be used in the saponification reaction include methanol, methyl acetate, dimethyl sulfoxide, dimethylformamide, and the like. Of these solvents, methanol is preferred. The solvent used preferably has a water content adjusted. The water content of the solvent is preferably 0.001 to 1% by mass, more preferably 0.003 to 0.9% by mass, and still more preferably 0.005 to 0.8% by mass.
The degree of saponification of PVA is usually 99.5 mol% or more, preferably 99.7 mol% or more, more preferably 99.9 mol% or more. When the degree of saponification is less than 99.5 mol%, the resulting polyvinyl acetal resin (B) has insufficient thermal stability, and it becomes difficult to perform stable melt molding by thermal decomposition or cross-linking gelation.

After the saponification reaction, the produced PVA is washed. Examples of the cleaning liquid include methanol, acetone, methyl acetate, ethyl acetate, hexane, and water. Among these, methanol, methyl acetate, water, or a mixture thereof is preferable.
It is preferable to set the usage-amount of a washing | cleaning liquid so that content of the alkali metal or alkaline-earth metal mentioned later may be satisfied, Usually, 300-10000 mass parts is preferable with respect to 100 mass parts of PVA, and 500-5000 masses. Part is more preferred. As washing | cleaning temperature, 5-80 degreeC is preferable and 20-70 degreeC is more preferable. The washing time is preferably 20 minutes to 100 hours, more preferably 1 hour to 50 hours.

  The content of alkali metal or alkaline earth metal in the PVA used in the present invention is preferably 0.00001 to 1 part by mass with respect to 100 parts by mass of PVA. Those having an alkali metal or alkaline earth metal content of less than 0.00001 parts by mass are industrially difficult to produce. In addition, when the content of alkali metal or alkaline earth metal is more than 1 part by mass, the content of alkali metal or alkaline earth metal remaining in the obtained polyvinyl acetal resin is increased, which causes decomposition and gelation. There are cases where stable melt molding cannot be performed. Examples of the alkali metal include sodium and potassium. Examples of alkaline earth metals include calcium and barium. Note that the content of alkali metal or alkaline earth metal can be determined by an atomic absorption method.

  The viscosity average degree of polymerization of PVA (hereinafter simply referred to as the degree of polymerization) is usually 500 to 2000, preferably 800 to 1700, and more preferably 1000 to 1500. When the degree of polymerization of PVA is less than 500, the mechanical properties of the resulting polyvinyl acetal resin (B) are insufficient, and the toughness may be particularly insufficient. On the other hand, when the polymerization degree of PVA exceeds 2000, the melt viscosity at the time of thermoforming as a polyvinyl acetal resin (B) becomes high, and it becomes difficult to produce a molded product.

  The degree of polymerization (P) of PVA is measured according to JIS-K6726. That is, it is obtained by the general formula (i) from the intrinsic viscosity [η] (dl / g) measured in water at 30 ° C. after completely re-saponifying and purifying PVA.

The aldehyde used for production of the polyvinyl acetal resin (B) is not particularly limited.
Examples of the aldehyde having 3 or less carbon atoms include formaldehyde (including paraformaldehyde), acetaldehyde (including paraacetaldehyde), propionaldehyde, and glyoxal. An aldehyde having 3 or less carbon atoms can be used alone or in combination of two or more. Of these aldehydes having 3 or less carbon atoms, those mainly composed of acetaldehyde (including paraacetaldehyde) and formaldehyde (including paraformaldehyde) are preferable, and acetaldehyde is particularly preferable.
Examples of the aldehyde having 4 or more carbon atoms include butyraldehyde, n-octylaldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, 2-ethylhexylaldehyde, cyclohexylaldehyde, furfural, glutaraldehyde, benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, Examples thereof include methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, β-phenylpropionaldehyde and the like. The aldehyde having 4 or more carbon atoms can be used alone or in combination of two or more. Of these aldehydes having 4 or more carbon atoms, butyraldehyde is particularly preferable from the viewpoint of ease of production. Moreover, as a combination of an aldehyde having 4 or more carbon atoms and an aldehyde having 3 or less carbon atoms used for the production of a polyvinyl acetal resin, a combination of butyraldehyde and acetaldehyde is preferable from the viewpoint of ease of production, heat resistance and mechanical properties. .

  The reaction between the polyvinyl alcohol resin and the aldehyde, that is, the acetalization reaction can be performed by a known method. For example, a method in which a polyvinyl alcohol resin is dissolved in water and reacted with an aldehyde in the presence of an acid catalyst to precipitate resin particles (aqueous medium method); a polyvinyl alcohol resin is dispersed in an organic solvent, and in the presence of an acid catalyst, A reaction with an aldehyde, and the resulting reaction solution is added to a poor solvent such as water to precipitate resin particles (solvent method). Of these, the aqueous medium method is preferred.

  The aldehydes used for acetalization may be charged all at the same time or may be charged separately one by one. The randomness of the vinyl acetal unit in the polyvinyl acetal resin can be changed by changing the addition order of the aldehyde, the addition order of the acid catalyst, the aging temperature and the time.

  The acid catalyst used in the acetalization reaction is not particularly limited. For example, organic acids such as acetic acid and p-toluenesulfonic acid; inorganic acids such as nitric acid, sulfuric acid and hydrochloric acid; and acidity when an aqueous solution such as carbon dioxide gas is used. Examples thereof include solid acid catalysts such as gases, cation exchangers and metal oxides.

  The degree of acetalization of the polyvinyl acetal resin (B) used in the present invention is usually 65 to 88 mol%, preferably 70 to 86 mol%, more preferably 75 to 84 mol%. The polyvinyl acetalized resin (B) having an acetalization degree of less than 65 mol% is not sufficiently heat-stable and has poor melt processability. On the other hand, a polyvinyl acetal resin having a degree of acetalization exceeding 88 mol% is very difficult to produce and requires a long time for the acetalization reaction, resulting in an increase in production cost. When a polyvinyl acetal resin having an acetalization degree in the above range is used, it is excellent in mechanical properties, particularly toughness, and a molded product can be obtained easily and inexpensively.

The degree of acetalization of the polyvinyl acetal resin can be determined according to the method described in JIS K6728 (1977) and the like.
First, the mass ratio (l ₀ ) of vinyl alcohol units that have not been acetalized and the mass ratio (m ₀ ) of vinyl acetate units are determined by titration. The mass ratio (k ₀ ) of the acetalized vinyl alcohol units is calculated by k ₀ = 1−l ₀ −m ₀ . From these, the molar ratio (l) of vinyl alcohol units that were not acetalized and the molar ratio (m) of vinyl acetate units were calculated, and the molar ratio of vinyl alcohol units that were acetalized by k = 1-l-m. (K) is calculated.
Alternatively, a polyvinyl acetal resin is dissolved in deuterated dimethyl sulfoxide, and ¹ H-MMR or ¹³ C-NMR is measured to determine the molar ratio (l) of vinyl alcohol units not acetalized, vinyl ester The molar ratio (m) of units and the molar ratio (k) of acetalized vinyl alcohol units are calculated. However, k ₀ + l ₀ + m ₀ = 1 and k + l + m = 1.
Then, the degree of acetalization is calculated by k / (k + 1 + m) × 100.

Further, when acetalization is performed with a plurality of aldehydes, the degree of acetalization for each aldehyde can be determined by the following method. For example, in a polyvinyl acetal resin obtained by acetalization with butyraldehyde, acetaldehyde and formaldehyde, the molar ratio k _{(BA) of} vinyl alcohol units acetalized with butyraldehyde, the molar ratio k of vinyl alcohol units acetalized with acetaldehyde _(AA) , the molar ratio k _{(FA) of} vinyl alcohol units acetalized with formaldehyde, the molar ratio l of vinyl alcohol units not acetalized, and the molar ratio m of vinyl ester units, The degree of conversion (also called the degree of butyralization) is determined by the formula: k _(BA) / {(k _(BA) + k _(AA) + k _(FA) ) + l + m} × 100. The degree of acetoacetalization is determined by the formula: k _(AA) / {(k _(BA) + k _(AA) + k _(FA) ) + l + m} × 100. The degree of formacetalization (also called the degree of formalization) is determined by the formula: k _(FA) / {(k _(BA) + k _(AA) + k _(FA) ) + l + m} × 100. In addition, the degree of acetalization for each aldehyde can be calculated by measuring the ratio of acetalized aldehyde by ¹ H-NMR or ¹³ C-NMR. However, k _(BA) + k _(AA) + k _(FA) + 1 + m = 1.

  The polyvinyl acetal resin (B) used in the present invention is preferably a resin obtained by acetalization with an aldehyde having 4 or more carbon atoms and an aldehyde having 3 or less carbon atoms. The polyvinyl acetal resin (B) used in the present invention is a vinyl alcohol unit acetalized with an aldehyde having 4 or more carbon atoms / vinyl alcohol acetalized with an aldehyde having 3 or less carbon atoms from the viewpoint of mechanical properties and heat resistance. The molar ratio of the units is preferably 90/10 to 0/100, more preferably 80/20 to 0/100, still more preferably 50/50 to 0/100, and particularly preferably 40/60 to 1/99. . By using such a polyvinyl acetal resin (B), the mechanical properties and heat resistance are maintained while maintaining the strength, elastic modulus, surface hardness, surface smoothness, transparency and the like inherent in the polyvinyl acetal resin. Can be obtained.

  The amount of vinyl ester units constituting the polyvinyl acetal resin is preferably 0.5 mol% or less, more preferably 0.3 mol% or less, and still more preferably 0.1 mol% or less. When there are more vinyl ester units than 0.5 mol%, a heat resistant fall, continuous productivity fall, etc. occur easily. When there are too many vinyl ester units, the thermal stability of the polyvinyl acetal resin (B) is not sufficient, and it tends to be difficult to perform stable melt molding by thermal decomposition or cross-linking gelation.

  In addition, since a polymerization degree does not change by acetalization, the polymerization degree of polyvinyl acetal resin (B) obtained by acetalizing the polyvinyl alcohol resin and the polyvinyl alcohol is the same. Therefore, the polymerization degree of the polyvinyl acetal resin (B) is preferably 500 to 2000, more preferably 800 to 1700, and still more preferably 1000 to 1500. When the degree of polymerization of the polyvinyl acetal resin (B) is less than 500, the mechanical properties of the polyvinyl acetal resin (B) tend to be insufficient, and in particular, the toughness tends to be insufficient. There exists a tendency for the melt viscosity at the time of shaping | molding to become high, and manufacture of a molded article becomes difficult.

  Since the slurry produced in the aqueous medium method and the solvent method is usually acidic due to the acid catalyst, it is preferable to remove the acid catalyst. As a method for removing the acid catalyst, the slurry is washed with water until the pH is preferably 6 to 8, more preferably 6.5 to 7.5; the pH is preferably increased by adding a neutralizing agent to the slurry. May be 6 to 8, more preferably 6.5 to 7.5, or alkylene oxides may be added. When the pH of the slurry is too low, the polyvinyl acetal resin is decomposed or cross-linked by the acid, and there is a tendency that a stable molded product cannot be obtained. On the other hand, when the pH of the slurry is too high, polymer degradation proceeds and the molded product tends to be colored.

  Examples of the neutralizing agent used for removing the acid catalyst include alkali metal compounds such as sodium hydroxide, potassium hydroxide, sodium acetate, sodium carbonate, sodium bicarbonate, potassium carbonate; alkaline earth such as calcium hydroxide. Metal compound; Ammonia, aqueous ammonia solution may be mentioned. Examples of the alkylene oxides used for removing the acid catalyst include ethylene oxide, propylene oxide; glycidyl ethers such as ethylene glycol diglycidyl ether.

Next, the catalyst residue, neutralizing agent residue, salt generated by neutralization, unreacted aldehyde, alkali metal, alkaline earth metal, by-product and the like are removed to purify the polyvinyl acetal resin.
The purification method is not particularly limited, and methods such as repeated liquid removal and washing are usually used. Examples of the liquid used for the purification include water and a mixed liquid obtained by adding alcohol such as methanol and ethanol to water. In particular, after neutralizing the polyvinyl acetal resin, the solution is removed with a mixed solution of water and alcohol (methanol, ethanol, etc.) until the pH is preferably 6 to 8, more preferably 6.5 to 7.5. And the method of repeating washing are preferable in that the alkali metal or alkaline earth metal can be efficiently reduced, and the polyvinyl acetal resin can be stably produced. The mixing ratio of water / alcohol is preferably 50/50 to 95/5 in mass ratio, and more preferably 60/40 to 90/10. When the ratio of water is too small, the elution of the polyvinyl acetal resin into the mixed solution tends to increase. When the proportion of water is too large, the removal efficiency of alkali metal or alkaline earth metal tends to decrease.

If a large amount of the above residues remain in the polyvinyl acetal resin (B), polymer deterioration may occur, and stable thermoforming may not be performed. Among them, the alkali metal contained in the neutralizing agent tends to cause thermal decomposition, and if it remains in a large amount, it may cause severe polymer decomposition or cross-linking gelation, and stable melt molding may not be performed.
Specifically, the alkali metal content in the polyvinyl acetal resin (B) is preferably 0.1 to 200 ppm, more preferably 0.1 to 50 ppm, and more preferably 0.1 to 10 ppm. Particularly preferred. In addition, when the content of alkali metal is less than 0.1 ppm, it is difficult to produce industrially, and it takes a long time for cleaning, so that the manufacturing cost increases. The method for removing the residue is not particularly limited, and methods such as repeated liquid removal and washing with water are usually used.

  The water-containing polyvinyl acetal resin (B) from which residues and the like have been removed is dried as necessary and processed into powder, granules, or pellets as necessary, and used for the production of the composition of the present invention. The It is preferable to reduce unreacted aldehyde, moisture, and the like by degassing under reduced pressure when processing into powder, granules, or pellets.

  Moreover, the moisture content of the polyvinyl acetal resin (B) used in the present invention is preferably 0.005 to 2%, more preferably 0.01 to 1%. Products with a moisture content of less than 0.005% are difficult to manufacture and have an excessive heat history, which may cause deterioration in quality such as coloring. On the other hand, when the moisture content exceeds 2%, it may be difficult to perform stable thermoforming by a normal forming method. The moisture content can be measured by the Karl Fischer method.

Furthermore, the main dispersion peak temperature Tα _B of the polyvinyl acetal resin (B) used in the present invention is preferably 85 ° C. to 125 ° C., more preferably 90 ° C. to 120 ° C. When Tα _B is less than 85 ° C., it may be difficult to provide a composition having excellent heat resistance. On the other hand, when Tα _B exceeds 125 ° C., the moldability may be reduced, and the use range may be limited.
The main dispersion peak temperature (Tα) can be determined by dynamic viscoelasticity measurement. For example, loss tangent measured using a DVE RHEOSPECTORER DVE-V4 manufactured by Rheology Co., Ltd., with a test piece having a length of 20 mm, a width of 3 mm, and a thickness of 120 to 200 μm measured under conditions of a sine wave vibration of 10 Hz and a heating rate of 3 ° C./min It can be obtained from (tan δ). The main dispersion peak temperature (Tα) is a temperature indicating a main dispersion peak of loss tangent (tan δ). In a broad sense, it may be called a glass transition temperature (Tg).

  The amount of the plasticizer contained in the polyvinyl acetal resin (B) used in the present invention is preferably 20 parts by mass or less, more preferably 10 parts by mass or less with respect to 100 parts by mass of the polyvinyl acetal resin. More preferably, the polyvinyl acetal resin (B) contains no plasticizer. When the amount of the plasticizer exceeds 20 parts by mass, the plasticizer bleeds out from the molded product, which tends to cause poor appearance. Examples of the plasticizer contained in the polyvinyl acetal resin (B) used in the present invention include carboxylic acid ester plasticizers such as monovalent carboxylic acid ester plasticizers and polyvalent carboxylic acid ester plasticizers; And polymeric plasticizers such as carboxylic acid polyester plasticizer, carbonic acid polyester plasticizer, and polyalkylene glycol plasticizer. These plasticizers may be used alone or in combination of two or more. Among these, triethylene glycol di-2-ethylhexanoate, triethylene glycol di-2-ethylbutyrate, triethylene glycol di-n-heptanoate, tetraethylene glycol di-2-ethyl are excellent in plasticizing effect. Hexanoate and tetraethylene glycol n-heptanoate are preferred.

  Furthermore, an ultraviolet absorber can be added to the polyvinyl acetal resin (B) used in the present invention for the purpose of improving the weather resistance. Although the kind of ultraviolet absorber is not specifically limited, A benzotriazole type, a benzophenone type, or a triazine type is preferable. The addition amount of the ultraviolet absorber is usually 0.1 to 10% by mass, preferably 0.1 to 5% by mass, and more preferably 0.1 to 2% by mass with respect to the polyvinyl acetal resin.

  In the acrylic thermoplastic resin composition of the present invention, the mass ratio (A) / (B) of the methacrylic resin (A) and the polyvinyl acetal resin (B) is preferably 99/1 to 1/99, more preferably. Is 99/1 to 51/49, more preferably 95/5 to 60/40, and particularly preferably 90/10 to 60/40. When the proportion of the polyvinyl acetal resin (B) is too small, mechanical properties such as toughness and impact resistance of the acrylic thermoplastic resin composition of the present invention tend to be lowered. On the other hand, when the proportion of the polyvinyl acetal resin (B) is too large, the surface hardness (and rigidity) of the acrylic thermoplastic resin composition of the present invention tends to be insufficient.

The resin composition containing the methacrylic resin (A) and the polyvinyl acetal resin (B) includes a main dispersion peak temperature (Tα _AP ) due to the methacrylic resin (A) in the resin composition, and the resin And a main dispersion peak temperature (Tα _BP ) due to the polyvinyl acetal resin (B) in the composition. Further, in the thermoplastic resin composition according to the present invention, only one main dispersion peak temperature may be observed. That is, Tα _AP = Tα _BP may be satisfied. When Tα _AP = Tα _BP , it indicates that the methacrylic resin (A) and the polyvinyl acetal resin (B) in the thermoplastic resin composition are in a completely compatible state.

In the acrylic thermoplastic resin composition of the present invention, the main dispersion peak temperature (Tα _AP ) due to the methacrylic resin (A) in the thermoplastic resin composition is the main dispersion peak of the methacrylic resin (A) alone. It is preferably a value between the temperature (Tα _A ) and the main dispersion peak temperature (Tα _B ) of the polyvinyl acetal resin (B) alone. That is, it is preferable that the relationship of Tα _B <Tα _AP <Tα _A or Tα _A <Tα _AP <Tα _B is satisfied. Such satisfy the relationship thermoplastic acrylic resin composition of the present invention with T [alpha _AP is ready to methacrylic resin (A) and the polyvinyl acetal resin (B) is partially or completely miscible It is thought that there is. In the present invention, when the methacrylic resin (A) is a combination of two or more methacrylic resins, and any one of the primary dispersion peak temperature of a combination thereof with T [alpha _A, polyvinyl acetal resin (B ) Is a combination of two or more polyvinyl acetal resins, the main dispersion peak temperature of any one of the combinations is Tα _B , and the above relationship, that is, Tα _B <Tα _AP <Tα _A , or Tα _A It is sufficient if the relationship <Tα _AP <Tα _B is satisfied.
When the methacrylic resin (A) and the polyvinyl acetal resin (B) are partially or completely compatible, the acrylic thermoplastic resin composition of the present invention has heat resistance, surface hardness and rigidity. Is almost the same as methacrylic resin, and it becomes difficult to whiten when stretched, folded, subjected to impact, and / or placed under wet heat conditions for a long time. In addition, it has excellent toughness and handleability.

In the acrylic thermoplastic resin composition of the present invention, the continuous phase is preferably formed of a methacrylic resin (A). In the acrylic thermoplastic resin composition of the present invention, the dispersed phase dyed with ruthenium tetroxide may be visible with an electron microscope. The dyed dispersed phase is considered to contain the polyvinyl acetal resin (B). The dispersed phase is preferably very small or absent. The average diameter of the dispersed phase is usually 200 nm or less, preferably 100 nm or less, particularly preferably 50 nm or less. In addition, when the average diameter of a dispersed phase is 0 nm, it includes that the polyvinyl acetal resin (B) is completely compatible with the methacrylic resin (A) and there is no visible dispersed phase.
In addition, the observation of the phase structure of the thermoplastic resin composition is performed by, for example, producing an ultrathin section using an ultramicrotome (Reichert ULTRACUT-S manufactured by RICA), followed by electron staining with ruthenium tetroxide, and Hitachi, Ltd. This is performed using a transmission electron microscope H-800NA.

A suitable method for obtaining the acrylic thermoplastic resin composition of the present invention is to mix the methacrylic resin (A) and the polyvinyl acetal resin (B), preferably under melting conditions, and then to a resin temperature of 160 ° C. It includes a step of raising the temperature to the above and then cooling to a resin temperature of 120 ° C. or lower.
Another suitable production method includes a step of melt-kneading the methacrylic resin (A) and the polyvinyl acetal resin (B) at a resin temperature of 140 ° C. or higher and then cooling to a resin temperature of 120 ° C. or lower.
A particularly preferred production method is a step of applying shear at a shear rate of 100 sec ⁻¹ or more to the step of melt-kneading the methacrylic resin (A) and the polyvinyl acetal resin (B) at a resin temperature of 160 ° C. or higher, And a step of setting the shear rate to 50 sec ⁻¹ or less at least twice.

  The melt kneading of the methacrylic resin (A) and the polyvinyl acetal resin (B) is performed using a known kneader such as a single screw extruder, a twin screw extruder, a Banbury mixer, a brabender, an open roll, a kneader. preferable. Among these kneaders, the methacrylic resin (A) is easy to form a continuous phase, and is excellent in productivity, so a twin screw extruder is preferable.

The resin temperature at the time of melt kneading is preferably 140 ° C. or higher, more preferably 140 to 270 ° C., and particularly preferably 160 to 250 ° C. Shear applied to the thermoplastic acrylic resin composition during the melt-kneading is preferably a shear rate is 100 sec ^-1 or more, and more preferably 200 sec ^-1 or more.

  In the production method of the present invention, it is preferable to raise the temperature to a resin temperature of 160 ° C. or higher, or melt and knead the resin at a temperature of 140 ° C. or higher, and then cool to a temperature of 120 ° C. or lower. Cooling is preferably performed more rapidly than natural cooling by, for example, immersing a melted strand in a tank in which cold water is stored. By rapid cooling, the methacrylic resin (A) forms a continuous phase, and the methacrylic resin (A) and the polyvinyl acetal resin (B) are easily partially or completely compatible. Furthermore, the size of the dispersed phase becomes very small.

In the acrylic thermoplastic resin composition of the present invention, various additives as necessary, for example, antioxidants, stabilizers, lubricants, processing aids, antistatic agents, colorants, impact resistance aids, foaming Agents, fillers, matting agents and the like may be added. In addition, it is preferable not to add a large amount of softener or plasticizer from the viewpoint of the mechanical properties and surface hardness of the acrylic thermoplastic resin composition.
Furthermore, an ultraviolet absorber can be added for the purpose of improving the weather resistance. Although the kind of ultraviolet absorber is not specifically limited, A benzotriazole type, a benzophenone type, or a triazine type is preferable. The addition amount of the ultraviolet absorber is usually 0.1 to 10% by mass, preferably 0.1 to 5% by mass, and more preferably 0.1 to 2% by mass with respect to the acrylic thermoplastic resin composition. It is.
In addition, the said additive added to the acrylic thermoplastic resin composition of this invention may be added to the methacrylic resin (A) or / and polyvinyl acetal resin (B) used as a raw material, or acrylic heat It may be added when the plastic resin composition is produced, or may be added when the acrylic thermoplastic resin composition is molded.

  The acrylic thermoplastic resin composition of the present invention is used, for example, as a molding material having a powder shape or a pellet shape. And using this molding material, various molded products can be manufactured by performing known molding methods such as extrusion molding, injection molding, vacuum molding, pressure molding, blow molding, transfer molding, rotational molding, powder slush, etc. it can.

  Applying the acrylic thermoplastic resin composition of the present invention to a melt extrusion method and an injection molding method in which a high shear force is applied to a thermoplastic resin composition such as a T-die method, a calender method, an inflation method, It is preferable for obtaining a molded product having excellent transparency, improved toughness, excellent handleability, and excellent balance between toughness, surface hardness and rigidity. In order to obtain a film-shaped molded product, the T-die method is preferably used in that a relatively economical and high-quality product can be obtained.

  A preferable resin temperature for performing melt molding is 160 to 270 ° C. After molding, it is preferable to cool the molded product more rapidly than natural cooling. For example, it is preferable that the film-shaped molded product immediately after being extruded is brought into contact with a cooling roll and rapidly cooled. By performing such rapid cooling, the dispersed phase becomes smaller and relaxation is less likely to occur, so that a high-quality molded product can be obtained.

  Various molded articles can be obtained by molding the thermoplastic resin composition of the present invention. For example, billboard parts such as advertising towers, stand signboards, sleeve signboards, billboard signs, rooftop signs, and marking films; display parts such as showcases, dividers, and store displays; fluorescent light covers, mood lighting covers, lamp shades, and light ceilings Lighting parts such as light walls and chandeliers; Interior parts such as furniture, pendants and mirrors; Building parts such as doors, domes, safety window glass, partitions, staircases, balcony stools, and roofs of leisure buildings; , Parts for transport equipment such as pilot visors, motorcycles, motorboat windshields, bus shading plates, automotive side visors, rear visors, head wings, headlight covers, automotive interior parts, bumper and other automotive exterior parts; , Stereo cover, TV protective mask, vending machine, mobile phone Electronic equipment parts such as telephones and personal computers; medical equipment parts such as incubators and X-ray parts; equipment-related parts such as machine covers, instrument covers, experimental equipment, rulers, dials, and observation windows; LCD protective plates, light guide plates, guides Optical parts such as optical films, Fresnel lenses, lenticular lenses, front plates and diffusers for various displays; traffic-related parts such as road signs, guide boards, curved mirrors, soundproof walls; other greenhouses, large tanks, box tanks, Examples include bathroom members, clock panels, bathtubs, sanitary, desk mats, game parts, toys, masks for face protection when welding; surface materials used for personal computers, mobile phones, furniture, vending machines, bathroom members, and the like.

  When the acrylic thermoplastic resin composition of the present invention is used, it has an excellent balance of toughness, impact resistance, surface hardness and rigidity, is easy to handle, and is stretched, bent and / or impacted. Since it does not sometimes whiten, a molded product having excellent appearance can be obtained. When a film-like or sheet-like molded product comprising the acrylic thermoplastic resin composition of the present invention is molded by bonding, laminating, insert molding, or in-mold molding to a substrate made of steel, plastic sheet, wood, glass, etc. The appearance of these substrates can be improved and the substrates can be protected. Furthermore, by applying a coating layer that is cured by irradiation with ultraviolet rays (UV) or electron beams (EB) on the acrylic thermoplastic resin composition of the present invention combined with a base material, the appearance and beauty can be further improved. The protection can be increased. The external appearance beauty of the substrate can be improved by co-extruding the acrylic thermoplastic resin composition of the present invention and a substrate made of steel, plastic, wood, glass or the like. In addition, taking advantage of its excellent appearance, it is suitable for wallpaper; automotive interior member surface; automotive exterior member surface such as bumper; mobile phone surface; furniture surface; personal computer surface; vending machine surface; Can be used.

  EXAMPLES Hereinafter, an Example is shown and this invention is demonstrated more concretely. However, the present invention is not limited to these examples. In the examples, “part” represents “part by mass” unless otherwise specified, and “%” represents “% by mass” unless otherwise specified.

(Weight average molecular weight)
Using Tetrahydrofuran as a solvent, Shodex (trademark) GPC SYSTEM11 manufactured by Showa Denko KK was connected to Shodex (trademark) KF-806L as a column for gel permeation chromatography, and Shodex (trademark) differential refractive index detector RI as a detector. Measured using -101. The sample solution was prepared by accurately weighing 3 mg of the polymer, dissolving it in 3 ml of tetrahydrofuran, and filtering it with a 0.45 μm membrane filter. The flow rate during the measurement was 1.0 ml / min, and the weight average molecular weight (Mw) was calculated as the molecular weight in terms of polymethyl methacrylate based on a calibration curve prepared with standard polymethyl methacrylate manufactured by Polymer Laboratories.

(Degree of acetalization)
The composition of the polyvinyl acetal resin (B) was determined by measuring the ¹³ C-NMR spectrum, so that the mol% (k _(BA) ) and carbon of the vinyl alcohol unit acetalized with an aldehyde having 4 or more carbon atoms with respect to all repeating units. The mol% (k _(AA) ) of vinyl alcohol units acetalized with an aldehyde of several formulas or less with respect to all repeating units was calculated.

(Alkali metal content)
The polyvinyl acetal resin (B) was carbonized with a platinum crucible and a hot plate, then incinerated with an electric furnace, and the residue was dissolved in an acid and measured using an atomic absorption photometer.

(Main dispersion peak temperature (Tα))
Using a DVE RHEOSPECTORER DVE-V4 manufactured by Rheology Co., Ltd., a test piece measuring 20 mm in length, 3 mm in width, and 200 μm in thickness is measured under conditions of a distance between chucks of 10 mm, a sinusoidal vibration of 10 Hz, and a heating rate of 3 ° C./min. The main dispersion peak temperature (Tα) of the loss tangent (tan δ) was obtained.

(Morphological observation by transmission electron microscope)
The acrylic thermoplastic resin composition was melt-kneaded and then cooled. Ultra-thin sections were prepared using an ultramicrotome (Richert ULTRACUT-S manufactured by RICA). The section was electron-stained with ruthenium tetroxide to prepare a sample. The polyvinyl acetal resin (B) portion in the acrylic thermoplastic resin composition was dyed. The morphology of the sample thus prepared was observed using a transmission electron microscope H-800NA manufactured by Hitachi, Ltd. In the observed morphology, the unstained portion (methacrylic resin (A)) formed a continuous phase, and the methacrylic resin (A) was discontinuous was evaluated as x. Moreover, the average dispersed particle diameter of the dyed polyvinyl acetal resin (B) portion was measured.

(Thermal stability)
Using “SDTQ600” manufactured by TA Instruments, the temperature was increased from 30 ° C. to 260 ° C. at a temperature increase rate of 10 ° C./min under the condition of a nitrogen flow rate of 100 ml / min. “The weight reduction ratio (wt%) of the thermoplastic resin composition with respect to the mass of the thermoplastic resin composition immediately after reaching 260 ° C., that is, the weight reduction ratio (wt%) = [(weight at the start of temperature increase (30 ° C.) -Weight at the end of temperature rise (after holding at 260 ° C for 60 minutes) / weight at the end of temperature rise (after holding at 260 ° C for 60 minutes)] x 100 " It shows that thermal stability is excellent, so that the value of this weight reduction ratio (wt%) is small.

(YI, visible light transmittance)
Using a spectrophotometer U-4100 manufactured by Hitachi High-Technologies Corporation, a film having a thickness of 100 μm was measured. The visible light transmittance was calculated according to JIS-R3106 by measuring the transmittance at a wavelength of 380 to 780 nm.

(Haze)
A film having a thickness of 100 μm was measured according to JIS-K7136.

(Number of items)
Using a polarizing microscope and a fluorescence microscope, for the film of an acrylic thermoplastic resin composition having a thickness of 100 μm and a size of 10 cm × 10 cm, the number of irregularities was counted 1 hour and 6 hours after the start of film formation.

(Gel evaluation)
Gel evaluation was performed as an index of continuous productivity. The pellets of each composition obtained with a twin screw extruder were heat treated at 260 ° C. for 2 hours. 500 mg of the pellet was dissolved in 50 g of tetrahydrofuran, and this solution was filtered with a membrane filter. This filter was dried by vacuum drying, and the gel fraction was evaluated from the weight increase. It shows that it is excellent in heat resistance, so that this gel fraction is small.

(Formability)
From the viewpoints of the viscosity of the molten resin at the time of thermoforming, the strength of the obtained film, etc., it was evaluated whether or not the film could be produced continuously and stably.

Production Example 1 [Methacrylic resin]
A methacrylic resin (A-1) comprising 91% by mass of methyl methacrylate units and 9% by mass of methyl acrylate units was produced by a bulk polymerization method. The produced methacrylic resin had a weight average molecular weight (Mw) of 100,000 and a main dispersion peak temperature Tα _A of 128 ° C.

Production Example 2 [Polyvinyl Acetal Resin]
A polyvinyl alcohol resin having a viscosity average polymerization degree and a saponification degree shown in Table 1 was dissolved in water. The aqueous solution was cooled to 12 ° C. Thereafter, a predetermined amount of butyraldehyde and / or acetaldehyde and 60% by mass of nitric acid were added and agitated by stirring. As the reaction progressed, resin precipitated. After completion of the reaction, washing was performed with excess water until pH = 6. It was then added to the alkaline aqueous medium and suspended by stirring. Wash again with water until pH = 7. By drying until the volatile content becomes 1.0%, polyvinyl acetal resins (B-1) to (B-14) and (B-16) to (B-19) having the characteristics shown in Table 1 are obtained. It was.

The composition of the polyvinyl acetal resin is determined by measuring ¹³ C-NMR, so that the mol% (k _(BA) ) of the vinyl alcohol unit acetalized with an aldehyde having 4 or more carbon atoms with respect to all repeating units, 3 or less carbon atoms. The mol% (k _(AA) ) of vinyl alcohol units acetalized with aldehydes with respect to all repeating units was calculated.

Example 1
75 parts of methacrylic resin (A-1) and 25 parts of polyvinyl acetal resin (B-1) were kneaded at a cylinder temperature of 230 ° C. and a screw rotation speed of 100 rpm using a LABO PLASTOMILL 2D30W2 twin screw extruder manufactured by Toyo Seiki. An acrylic thermoplastic resin composition was obtained. The resin temperature immediately before finishing the kneading was 260 ° C. Morphological observation of the obtained acrylic thermoplastic resin composition was performed, and these results are shown in Table 2.
Furthermore, the thin film sample was produced by extruding the pellet of the obtained acrylic thermoplastic resin composition using Toyo Seiki's LABO PLASTOMILL D2025. The physical property evaluation results are shown in Table 2.

Examples 2-14
An acrylic thermoplastic resin composition was obtained in the same manner as in Example 1 except that the polyvinyl acetal resins (B-2) to (B-14) were used instead of the polyvinyl acetal resin (B-1). Evaluation of physical properties and morphology observation of the obtained acrylic thermoplastic resin composition were carried out in the same manner as in Example 1. These results are shown in Tables 2 and 3.

Example 15
10 parts by mass of triethylene glycol di-2-ethylhexanoate was added as a plasticizer to 100 parts by mass of the polyvinyl acetal resin (B-1) obtained in Example 1. The polyvinyl acetal resin (B-15) obtained by adding the plasticizer is kneaded at a cylinder temperature of 230 ° C. and a screw rotation speed of 100 rpm using a LABO PLASTOMILL 2D30W2 twin screw extruder manufactured by Toyo Seiki Co., Ltd. A plastic resin composition was obtained. The resin temperature immediately before finishing the kneading was 260 ° C. Furthermore, the thin film sample was produced by extruding the pellet of the obtained acrylic thermoplastic resin composition using Toyo Seiki's LABO PLASTOMILL D2025. The produced film was evaluated in the same manner as in Example 1. The results are shown in Table 3.

Comparative Examples 1-3
In the same manner as in Example 1, except that the polyvinyl acetal resins (B-16) to (B-18) shown in Table 3 were used instead of the polyvinyl acetal resin (B-1) used in Example 1. Pellets and films were obtained and evaluated. The results are shown in Table 3.

  For Comparative Example 1, a polyvinyl acetal resin (B-16) produced using a polyvinyl alcohol resin having a polymerization degree of 360 was used. As a result, the film of the acrylic thermoplastic resin composition was small and brittle, so that the film could not be continuously taken up and the film could not be produced continuously. Conversely, for Comparative Example 2, a polyvinyl acetal resin (B-17) produced using a polyvinyl alcohol resin having a polymerization degree of 2400 was used. As a result, since the viscosity of the molten resin of the acrylic thermoplastic resin composition is large and the resin cannot be stably discharged from the T-die, the take-up cannot be continued, and the torque gradually increases, and the continuous Film could not be produced. Moreover, about the comparative example 3, the polyvinyl acetal resin (B-18) produced using the polyvinyl alcohol resin of saponification degree 98.5 mol% was used. As a result, in the film of the acrylic thermoplastic resin composition, the number of bumps greatly increased in the film after 6 hours as compared with the film after 1 hour from the start, and the state of the film deteriorated.

Comparative Example 4
A pellet and a film were obtained in the same manner as in Example 1 except that the polyvinyl acetal resin (B-19) shown in Table 2 was used instead of the polyvinyl acetal resin (B-1) used in Example 1. And evaluated them. The results are shown in Table 3.

  Comparative Example 4 was prepared using a polyvinyl acetal resin (B-19) having an acetalization degree of 54 mol%. As a result, compared with the film 1 hour after the start, the number of bumps increased significantly in the film after 6 hours, and the film state deteriorated. Ma

Claims (11)

A methacrylic resin (A);
Acrylic containing a polyvinyl acetal resin (B) obtained by acetalizing a polyvinyl alcohol resin having a viscosity average polymerization degree of 500 to 2000 and a saponification degree of 99.5 mol% or more at an acetalization degree of 65 to 88 mol% -Based thermoplastic resin composition.   The acrylic thermoplastic resin composition of Claim 1 which contains a plasticizer at 20 mass parts or less with respect to 100 mass parts of polyvinyl acetal resin (B).   The acrylic thermoplastic resin composition according to claim 1 or 2, wherein the polyvinyl acetal resin (B) contains no plasticizer.   The polyvinyl acetal resin (B) is obtained by acetalizing a polyvinyl alcohol resin, adjusting the pH of the obtained slurry to 6 to 8, and then performing a drying treatment. The acrylic thermoplastic resin composition as described in one.   5. The acrylic thermoplastic resin composition according to claim 1, wherein the polyvinyl acetal resin (B) is adjusted to a moisture content of 0.005 to 2%. The polyvinyl acetal resin (B) is a resin obtained by acetalization with an aldehyde having 4 or more carbon atoms and an aldehyde having 3 or less carbon atoms,
The total amount of vinyl alcohol units acetalized with aldehyde is 65 to 88 mol% of all repeating units, and acetalized with vinyl alcohol units acetalized with aldehydes having 4 or more carbon atoms / aldehydes with 3 or less carbon atoms. The acrylic thermoplastic resin composition according to any one of claims 1 to 5, wherein the molar ratio of the vinyl alcohol units is 90/10 to 0/100.   The acrylic thermoplastic according to any one of claims 1 to 6, wherein the mass ratio (A) / (B) of the methacrylic resin (A) to the polyvinyl acetal resin (B) is 99/1 to 51/49. Resin composition.   A molded article comprising the acrylic thermoplastic resin composition according to any one of claims 1 to 7.   The film which consists of an acryl-type thermoplastic resin composition as described in any one of Claims 1-7.   The manufacturing method of a molded article including heat-molding the acrylic thermoplastic resin composition as described in any one of Claims 1-7.   The manufacturing method of a film including heat-molding the acrylic thermoplastic resin composition as described in any one of Claims 1-7.