JP2008133452A - Acrylic thermoplastic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acrylic thermoplastic resin composition improved in toughness while retaining features a methacrylic resin inherently has, such as transparency, high surface hardness, high rigidity, weatherability and heat resistance. <P>SOLUTION: The resin composition is obtained by melt-kneading a methacrylic resin (A) with a polyvinyl acetal resin (B) under at least 100 sec<SP>-1</SP>shearing and at ≥140°C resin temperature followed by cooling thereof to ≤120°C, wherein at least the methacrylic resin (A) forms a continuous phase. In the glass transition temperatures of the resin composition, a glass transition temperature Tg<SB>AP</SB>deriving from the methacrylic resin (A) shows a value between the glass transition temperature (Tg<SB>A</SB>) of the methacrylic resin (A) alone and the glass transition temperature (Tg<SB>B</SB>) of the polyvinyl acetal resin (B) alone. A film- or sheet-shaped molded product is obtained by molding the resin composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an acrylic thermoplastic resin composition from which a transparent molded article having improved toughness can be obtained, in particular, when stretched, bent, subjected to an impact, and / or subjected to long-term wet heat conditions. The present invention relates to an acrylic thermoplastic resin composition capable of obtaining a molded product that does not whiten when left to stand. The present invention also relates to an acrylic thermoplastic resin composition from which a transparent molded article having an excellent balance between surface hardness, rigidity and toughness can be obtained.

  Thermoplastic polymer (methacrylic resin) mainly composed of poly (methyl methacrylate) has excellent properties in transparency (high total light transmittance in the visible light region) and surface hardness. in use. However, this methacrylic resin may lack mechanical properties, particularly toughness, depending on the application, and improvements are required.

  As a method for improving mechanical properties, core-shell type particles composed of a rubber layer and a methacrylic resin layer synthesized by emulsion polymerization are converted into a thermoplastic polymer (methacrylic resin) mainly composed of polymethyl methacrylate. A blending method is generally used. However, the molded article made of the composition obtained by this method is improved in impact resistance but insufficient in toughness. Moreover, due to the blending of the rubber component, the surface hardness decreases, the rigidity decreases, Causes a decrease in heat resistance. In addition, when stress is applied during tension or bending, the stress concentration portion may be whitened. Furthermore, it may be whitened when subjected to an impact or when left under a wet and heat condition for a long time. In addition, the whitening causes transparency to be lost, and the design and high-quality feeling of the molded body are likely to be impaired.

  As another method for improving the toughness of the methacrylic resin, a method of copolymerizing methyl methacrylate with another monomer that lowers the glass transition temperature has been proposed. However, this method has a problem that the rigidity and heat resistance are greatly reduced.

A methacrylic resin composition obtained by blending another polymer with a methacrylic resin has been proposed.
As other polymers blended with the methacrylic resin, for example, polymers such as styrene-acrylonitrile copolymer, polyvinyl chloride, and polyvinylidene fluoride having a specific composition have been proposed. However, toughness cannot be sufficiently improved by blends of these polymers.

  It has been proposed to use polyethylene oxide as a polymer for blending. This polyethylene oxide is excellent in miscibility with polymethyl methacrylate and can be expected to improve toughness. However, since the glass transition temperature is low, a decrease in rigidity and heat resistance of the blend cannot be avoided.

  Polycarbonate is mentioned as a polymer that can be expected to improve the balance of toughness, heat resistance, and transparency. The transparent composition of bisphenol A polycarbonate and polymethyl methacrylate is prepared by, for example, dissolving polymethyl methacrylate and polycarbonate in tetrahydrofuran, adding the solution to heptane and precipitating the polymethacrylic acid. It is reported to be obtained by heat treatment above the glass transition temperature of methyl and polycarbonate. However, a molded body made of the composition has a low surface hardness and uses a solvent for preparing the composition. Therefore, a large amount of energy is required to remove the solvent and productivity is low. A method of melt-kneading polycarbonate and polymethyl methacrylate has also been reported. However, in the composition obtained by melt-kneading, the polycarbonate and polymethyl methacrylate are phase-separated to become an opaque molded body having pearly luster (Non-patent Document 1).

Polyvinyl butyral is an example of a polymer that is compatible with polymethyl methacrylate.
In Non-Patent Document 2, methyl methacrylate resin and polyvinyl butyral are poorly compatible, and those obtained by mixing them usually have a two-phase structure by phase separation, but methacryl having a low molecular weight. It is described that when an acid methyl resin is used, there is a possibility that it may become compatible and become a single phase. FIG. 5 of Non-Patent Document 2 was obtained by dissolving a blend of 50 parts by mass of polyvinyl butyral and 50 parts by mass of a methyl methacrylate resin containing various amounts of vinyl alcohol units in a solvent and cast molding. An optical microscope image of the film is shown. This film has a phase separation structure in which methyl methacrylate resin is dispersed in various sizes.

  Non-Patent Document 3 describes that polymethyl methacrylate having a weight average molecular weight of 120,000 and polyvinyl butyral were melt-kneaded at various ratios to obtain blends. Non-patent document 3 describes that a blend having a large proportion of polyvinyl butyral has an increased elongation at break in a tensile test, yield behavior is observed, and toughness is improved. However, the blend with a large proportion of polyvinyl butyral described in Non-Patent Document 3 has insufficient mechanical properties. On the other hand, the blend in which less than 50% by mass of polyvinyl butyral was mixed had almost no improvement effect on toughness and insufficient mechanical properties.

  Furthermore, Patent Document 1 discloses a resin composition comprising a block copolymer containing a methacrylic copolymer block and an acrylic polymer block, and a plasticized polyvinyl acetal resin. Patent Document 1 describes that this resin composition is used for bonding two glass plates and suppresses the whitening phenomenon caused by contact with the atmosphere. However, this resin composition has a very low surface hardness.

Journal of Polymer Science PART B, Polymer Physics, Vol.25, 1459 (1987) Macromolecules, Vol.34, 4277 (2001) J. Ind. Eng. Chem., Vol. 8, No. 6, 530 (2002) JP 2003-40653 A

  An object of the present invention is to provide an acrylic thermoplastic resin composition having improved toughness while retaining the features such as transparency, high surface hardness, high rigidity, weather resistance, and heat resistance inherent in methacrylic resins. In particular, it is to provide an acrylic thermoplastic resin composition that does not whiten when stretched, bent, impacted, or left for a long time under wet heat conditions. Furthermore, another object of the present invention is to provide a molded article that exhibits the characteristics of the acrylic thermoplastic resin composition effectively, particularly a film (in the present invention, the term “film” means that the thickness is usually 500 μm or less. Is to provide).

As a result of intensive studies to achieve the above object, the present inventors have melt-kneaded a methacrylic resin and a polyvinyl acetal resin under specific conditions, so that at least the methacrylic resin (A) forms a continuous phase. and which, polyvinyl glass transition temperature Tg _AP due to methacrylic resin (a) of the glass transition temperature of the acrylic thermoplastic resin composition, the methacrylic resin (a) alone with a glass transition temperature of the (Tg _a) It has been found that an acrylic thermoplastic resin composition showing a value between the glass transition temperature (Tg _B ) of the acetal resin (B) alone can be obtained. The acrylic thermoplastic resin composition has good toughness while maintaining the properties such as transparency, high surface hardness, high rigidity, weather resistance, and heat resistance inherent in methacrylic resins. I found out. And it discovered that even if the molded object and film which consist of this composition were extended | stretched, bend | folded, or given an impact, and it was left to stand for a long time in a moist heat condition, it hardly found whitening. Furthermore, it has been found that a molded article (film) made of the acrylic thermoplastic resin composition of the present invention has a higher tear strength and greatly improves handleability compared to a film made only of a methacrylic resin.
The present invention has been further studied and completed based on these findings.

That is, the present invention is an acrylic thermoplastic resin composition comprising a methacrylic resin (A) and a polyvinyl acetal resin (B), wherein at least the methacrylic resin (A) forms a continuous phase. Among the glass transition temperatures of the acrylic thermoplastic resin composition, the glass transition temperature Tg _AP resulting from the methacrylic resin (A) is the glass transition temperature (Tg _A ) of the methacrylic resin (A) alone and polyvinyl acetal. It is an acrylic thermoplastic resin composition showing a value between the glass transition temperature (Tg _B ) of the resin (B) alone.
The resin composition is obtained by melt-kneading a methacrylic resin (A) and a polyvinyl acetal resin (B) at a resin temperature of 140 ° C. or higher while applying shear at a shear rate of 100 sec ⁻¹ or higher, and then at a temperature of 120 ° C. or lower. Obtained by cooling.

  The acrylic thermoplastic resin composition of the present invention has good toughness while maintaining the properties, such as transparency, high surface hardness, high rigidity, weather resistance, and heat resistance, originally possessed by methacrylic resins. . Molded bodies and films made of this composition hardly whiten even when stretched, bent, impacted, or left for a long time under wet heat conditions. Furthermore, since the molded body (film) made of the acrylic thermoplastic resin composition of the present invention has a higher tear strength than a film made only of a methacrylic resin, it is easy to handle. The acrylic thermoplastic resin composition of the present invention having such features can be used for a wider range of applications.

Hereinafter, the present invention will be described in detail.
The acrylic thermoplastic resin composition of the present invention comprises 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 an alkyl methacrylate.

  Examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, myristyl. Examples thereof include methacrylate, palmityl methacrylate, stearyl methacrylate, behenyl methacrylate, cyclohexyl methacrylate, and phenyl methacrylate. These alkyl metallates 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.

Examples of monomers other than alkyl methacrylate include alkyl acrylate. Other ethylenically unsaturated monomers that can be copolymerized with alkyl methacrylate and alkyl acrylate are also included.
As alkyl acrylates, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, pentyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, myristyl Examples include acrylate, palmityl acrylate, stearyl acrylate, behenyl acrylate, cyclohexyl acrylate, and phenyl acrylate. Of these, alkyl acrylates having 1 to 8 carbon atoms in the alkyl group are preferred. These alkyl acrylates may be used alone or in combination of two or more.

  Examples of the ethylenically unsaturated monomer copolymerizable with alkyl methacrylate and alkyl acrylate include diene compounds such as 1,3-butadiene and isoprene; styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, Styrene substituted with halogen, 1-vinylnaphthalene, 4-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene, etc. Vinyl aromatic compounds; ethylenically unsaturated nitriles such as acrylonitrile and methacrylonitrile; acrylic acid, methacrylic acid, acrylamide, methacrylamide, maleic anhydride, maleic imide, monomethyl maleate, dimethyl maleate, etc. It is possible. These ethylenically unsaturated monomers may be used alone or in combination of two or more.

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

The methacrylic resin (A) used in the present invention preferably has a weight average molecular weight (denoted as Mw, the same shall apply hereinafter) in terms of strength characteristics and meltability, preferably 40,000 or more, more preferably 40,000-10. , 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 bonded, may have a branch, or may have a cyclic structure. good.

  The methacrylic resin (A) used in the present invention is not particularly limited as long as it is a method capable of polymerizing an α, β-unsaturated compound, but 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 generally used in an amount of 0.05 to 0.5 parts by mass with respect to 100 parts by mass of all monomers. The polymerization is usually performed at a temperature of 50 to 140 ° C. for 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. A chain transfer agent is normally used in 0.005-0.5 mass% with respect to all the monomers.

  The methacrylic resin (A) used in the present invention contains various additives as necessary, for example, antioxidants, stabilizers, ultraviolet absorbers, lubricants, processing aids, antistatic agents, colorants, impact resistance. Auxiliaries, foaming agents, fillers, matting agents and the like may be blended. In addition, it is preferable that a softener and a plasticizer are not included abundantly from a viewpoint of the mechanical physical property and surface hardness of a thermoplastic resin composition.

  The polyvinyl acetal resin (B) is usually a resin having a repeating unit represented by Chemical Formula 1.

In Chemical Formula 1, n is the number of aldehyde types used in the acetalization (natural number), R ₁ , R ₂ ,..., R _n is the alkyl residue or hydrogen atom of the aldehyde used in the acetalization reaction, _{k (1), k (2} ), ···, k (n) each of R _1, R _2, · · ·, the proportion of acetal units containing R _n (mol ratio), l is the vinyl alcohol unit The ratio (mol ratio), m is the ratio (mol ratio) of vinyl acetate units. However, k ₍₁₎ + k ₍₂₎ + ... + k _(n) + l + m = 1, and k ₍₁₎ , k ₍₂₎ , ..., k _(n) , l, and m are any May be zero. The repeating units are not particularly limited by the arrangement order shown in Chemical Formula 1, and may be arranged at random, may be arranged in a block shape, or may be arranged in a taper shape.

  The polyvinyl acetal resin (B) used in the present invention can be obtained, for example, by reacting a polyvinyl alcohol resin and an aldehyde.

  The polyvinyl alcohol resin used for the production of the polyvinyl acetal resin has a number average degree of polymerization of usually 200 to 4,000, preferably 300 to 3,000, more preferably 500 to 2,000. If the number average polymerization degree of the polyvinyl alcohol resin is less than 200, the mechanical properties of the resulting polyvinyl acetal resin are insufficient, and the mechanical properties, particularly toughness, of the acrylic thermoplastic resin composition of the present invention tends to be insufficient. On the other hand, when the number average polymerization degree of the polyvinyl alcohol resin exceeds 4,000, the melt viscosity at the time of melt-kneading the acrylic thermoplastic resin composition of the present invention increases, and the acrylic thermoplastic resin composition of the present invention Manufacturing tends to be difficult.

A polyvinyl alcohol resin is not specifically limited by the manufacturing method, For example, what was manufactured by saponifying polyvinyl acetate etc. with an alkali, an acid, ammonia water, etc. can be used.
The polyvinyl alcohol resin may be completely saponified, or may be a partially saponified partially saponified polyvinyl alcohol resin. It is preferable to use a saponification degree of 80 mol% or more.

Further, as the polyvinyl alcohol resin, it is possible to use a copolymer of vinyl alcohol and a monomer copolymerizable with vinyl alcohol, such as an ethylene-vinyl alcohol copolymer resin or a partially saponified ethylene-vinyl alcohol copolymer resin. it can. Furthermore, a modified polyvinyl alcohol resin into which carboxylic acid or the like is partially introduced can be used.
These polyvinyl alcohol resins may be used alone or in combination of two or more.

  The aldehyde used for the production of the polyvinyl acetal resin is not particularly limited. For example, formaldehyde (including paraformaldehyde), acetaldehyde (including paraacetaldehyde), propionaldehyde, butyraldehyde, n-octylaldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, 2-ethylhexylaldehyde, cyclohexylaldehyde, furfural, glyoxal, Examples include glutaraldehyde, benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, β-phenylpropionaldehyde and the like. These aldehydes may be used alone or in combination of two or more. Among these aldehydes, those mainly composed of butyraldehyde are preferable from the viewpoint of ease of production.

A polyvinyl acetal resin (B) obtained by acetalizing a polyvinyl alcohol resin with an aldehyde mainly composed of butyraldehyde is particularly referred to as polyvinyl butyral. In the present invention, polyvinyl butyral having a butyral unit ratio (see the following formula) of acetal units present in the polyvinyl acetal resin exceeding 0.9 is preferable. That is, in the structural formula of the polyvinyl acetal resin shown in Chemical Formula ₁ , when R ₁ = C ₃ H ₇ (alkyl residue of butyraldehyde), k ₍₁₎ / (k ₍₁₎ + k ₍₂₎ + -It is preferable that + k _(n) )> 0.9.

  The reaction between the polyvinyl alcohol resin and the aldehyde ((co) acetalization reaction) can be performed by a known method. For example, an aqueous solution method in which an aqueous solution of a polyvinyl alcohol resin and an aldehyde are acetalized in the presence of an acid catalyst to precipitate resin particles, the polyvinyl alcohol resin is dispersed in an organic solvent, and the aldehyde and the aldehyde are present in the presence of an acid catalyst. Examples thereof include a solvent method in which an acetalization reaction is performed and the reaction solution is precipitated with water or the like which is a poor solvent for the polyvinyl acetal resin. Of these, the aqueous medium method is preferred.

  The acid catalyst is not particularly limited, and examples thereof include organic acids such as acetic acid and p-toluenesulfonic acid; inorganic acids such as nitric acid, sulfuric acid and hydrochloric acid; gas which shows acidity when an aqueous solution such as carbon dioxide gas is used, and cation exchange. And solid acid catalysts such as metal oxides and metal oxides.

The degree of acetalization of the polyvinyl acetal resin used in the present invention is preferably 55 to 83 mol%. By using a polyvinyl acetal resin having a degree of acetalization within this range, the acrylic thermoplastic resin composition of the present invention can be obtained easily and at low cost by melt processing or production.
In addition, the acetalization degree (mol%) of polyvinyl acetal resin (B) can be defined by the following formula | equation.
Acetalization degree (mol%) =
{K ₍₁₎ + k ₍₂₎ + ... + k _(n) } × 2
/ {{K ₍₁₎ + k ₍₂₎ +... + K _(n) } × 2 + l + m} × 100

The degree of acetalization of the polyvinyl acetal resin is determined by titration of the mass proportion of vinyl alcohol units (l ₀ ) and the proportion of vinyl acetate units (m ₀ ) according to the method described in JIS K6728 (1977). The mass ratio (k ₀ ) of the unit was determined by k ₀ = 1−l ₀ −m ₀ , and from this, the molar ratio (l) of vinyl acetate units and the molar ratio (m) of vinyl acetate units were calculated, k = 1− The ratio of vinyl acetal units (k = k ₍₁₎ + k ₍₂₎ +... + k _(n) ) is calculated by the formula of 1−m, and the degree of acetalization (mol%) = {k ₍₁₎ + k ₍₂₎ + ... + k _(n) } × 2 / {{k ₍₁₎ + k ₍₂₎ + ... + k _(n) } × 2 + l + m} × 100, or polyvinyl acetal resin Deuterated dimethylsulfoxy Was dissolved in Id, it may be calculated by measuring the ¹ H-MMR or ¹³ C-NMR,.

The ratio of acetalization with butyraldehyde is particularly called the degree of butyralization. In the structural formula of polyvinyl acetal shown in Chemical Formula ₁ , when R ₁ = C ₃ H ₇ (an alkyl residue of butyraldehyde), the degree of butyralization is defined by the following formula.
Butyral degree (mol%) = {k ₍₁₎ } × 2
/ {{K ₍₁₎ + k ₍₂₎ +... + K _(n) } × 2 + l + m} × 100
More preferably, the polyvinyl acetal resin used in the present invention has a butyralization degree of 55 to 75 mol%. That is, it is preferable that 0.55 ≦ k ₍₁₎ ≦ 0.75. When a polyvinyl acetal resin having a butyralization degree in the above range is used, it is excellent in mechanical properties, particularly toughness, and the acrylic thermoplastic resin composition of the present invention can be obtained easily and inexpensively. Further, when a polyvinyl acetal resin having a butyralization degree in the above range is used, the difference between the refractive index of the methacrylic resin (A) and the refractive index of the polyvinyl butyral is reduced, and the transparent characteristic of the methacrylic resin (A) is obtained. (High visible light transmittance, low haze) is easily maintained. Furthermore, when stretched, bent, subjected to an impact, and / or placed in a wet and heat condition for a long time, the feature of hardly whitening is likely to appear.

  A suitable polyvinyl acetal resin usually contains 17 to 45 mol% (0.17 ≦ l ≦ 0.45) of vinyl alcohol units and usually contains 0 to 5 mol% (0 ≦ m ≦ 0) of vinyl acetate units. 0.05), preferably 0 mol% or more and 3 mol% or less (0 ≦ m ≦ 0.03).

The slurry produced in the aqueous medium method and the solvent method is usually acidic due to an acid catalyst. As a method for removing the acid catalyst, the slurry is repeatedly washed with water, and the pH is usually adjusted to 5 to 9, preferably 6 to 9, more preferably 6 to 8; a neutralizing agent is added to the slurry, The method of adjusting pH to 5-9 normally, Preferably 6-9, More preferably, 6-8; The method of adding alkylene oxides etc. are mentioned.
Examples of the compound used for removing the acid catalyst include alkali metal compounds such as sodium hydroxide, potassium hydroxide, sodium acetate, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, ammonia, and an aqueous ammonia solution. Examples of alkylene oxides include ethylene oxide, propylene oxide; glycidyl ethers such as ethylene glycol diglycidyl ether.

Next, salts generated by neutralization, aldehyde reaction residues, and the like are removed. The removal method is not particularly limited, and methods such as repeated dehydration and water washing are usually used.
The water-containing polyvinyl acetal resin from which residues and the like have been removed is dried as necessary, processed into powder, granules, or pellets as necessary, and used as a molding material. When processing into a powder, granule, or pellet, it is preferable to reduce the aldehyde reaction residue, moisture, and the like by degassing under reduced pressure.

  The polyvinyl acetal resin used in the present invention includes various additives as necessary, for example, antioxidants, stabilizers, ultraviolet absorbers, lubricants, processing aids, antistatic agents, colorants, impact resistance aids, A foaming agent, a filler, a matting agent, etc. may be blended. In addition, it is preferable that a softener and a plasticizer are not included abundantly from a viewpoint of the mechanical physical property and surface hardness of a thermoplastic resin composition.

In the acrylic thermoplastic resin composition of the present invention, at least two glass transition temperatures are observed in dynamic viscoelasticity measurement. One is the glass transition temperature (Tg _AP ) due to the methacrylic resin (A) in the thermoplastic resin composition, and the other is due to the polyvinyl acetal resin (B) in the thermoplastic resin composition. Glass transition temperature (Tg _BP ).
When only one glass transition temperature of the thermoplastic resin composition can be observed, that is, when Tg _AP = Tg _BP , the methacrylic resin (A) and the polyvinyl acetal resin (B) in the thermoplastic resin composition Is in a completely compatible state.
When Tg _AP = Tg _A and Tg _BP = Tg _B , this indicates that the methacrylic resin (A) and the polyvinyl acetal resin (B) are in a completely incompatible state.

In contrast, the thermoplastic acrylic resin composition of the present invention, the glass transition temperature Tg _AP due to methacrylic resin in the thermoplastic resin composition (A) is methacrylic resin (A) alone Glass It is a value between the transition temperature (Tg _A ) and the glass transition temperature (Tg _B ) of the polyvinyl acetal resin (B) alone. That is, the relationship of Tg _B <Tg _AP <Tg _A or Tg _A <Tg _AP <Tg _B is satisfied. The acrylic thermoplastic resin composition of the present invention having Tg _AP satisfying such a relationship is considered that the methacrylic resin (A) and the polyvinyl acetal resin (B) are in a partially compatible state. It is done. The acrylic thermoplastic resin composition of the present invention has a continuous phase formed of at least a methacrylic resin (A).
In the present invention, the methacrylic resin (A) is a combination of two or more methacrylic resins, and any one of the glass transition temperature of the combination thereof with Tg _A, polyvinyl acetal resin (B) Is a combination of two or more polyvinyl acetal resins, the glass transition temperature of any one of the combinations is defined as Tg _B , and the above relationship, that is, Tg _B <Tg _AP <Tg _A , or Tg _A <Tg _{It is} only necessary to satisfy the relationship of _AP <Tg _B.

Although the detailed reason is not clear, when the methacrylic resin (A) and the polyvinyl acetal resin (B) are partially compatible, the thermoplastic resin composition of the present invention has a heat resistance, a surface hardness and a rigidity of methacrylic resin. It is almost the same as the base resin, and it is difficult to whiten when stretched, bent, subjected to an impact, and / or placed under humid heat conditions for a long time. In addition, it has excellent toughness and handleability.
On the other hand, when the methacrylic resin (A) and the polyvinyl acetal resin (B) are completely compatible, the surface hardness of the resin composition tends to decrease. Further, when the methacrylic resin (A) and the polyvinyl acetal resin (B) are completely compatible and Tg _B <Tg _A , the heat resistance tends to decrease. When the methacrylic resin (A) and the polyvinyl acetal resin (B) are completely incompatible, the strength decreases or whitens.

In the thermoplastic resin composition of the present invention, the mass ratio (A) / (B) between the methacrylic resin (A) and the polyvinyl acetal resin (B) is preferably 99/1 to 51/49. From the viewpoint of toughness, surface hardness and rigidity of the thermoplastic resin composition of the present invention, the mass ratio (A) / (B) is more preferably 95/5 to 60/40, and 90/10 to 60 / 40 is particularly preferred.
When the ratio of (B) is less than 1% by mass, the effect of improving the mechanical properties such as toughness of the thermoplastic resin composition of the present invention tends to decrease. On the other hand, when the ratio of (B) exceeds 49 mass%, the surface hardness (and rigidity) of the thermoplastic resin composition of the present invention tends to be insufficient.

According to JIS K7171, the acrylic thermoplastic resin composition of a preferred embodiment of the present invention uses a test piece having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm, and a strain rate of 1 mm / min. In accordance with the flexural modulus at the time of the test and the JIS K7162, a strain rate of 1 mm / min. At least one of the tensile elastic moduli when tested at 2 is 2 GPa or more, preferably 2.5 GPa or more, and more preferably 2.7 GPa or more.
Moreover, the acrylic thermoplastic resin composition according to a preferred embodiment of the present invention has a strain rate of 1 mm / min. Using a test piece of length 80 mm × width 10 mm × thickness 4 mm according to JIS K7171. It has a yield point of stress when it is subjected to a bending test. The yield point of stress is the stress limit where plastic deformation starts in a solid.
Furthermore, the acrylic thermoplastic resin composition according to a preferred embodiment of the present invention has a change in haze before and after being left for 1500 hours under conditions of a temperature of 60 ° C. and a humidity of 90% (the haze before being left and the haze after being left). Difference) is less than 1.0%.

The production method for obtaining such an acrylic thermoplastic resin composition of the present invention is such that a resin temperature of 140 is applied to a methacrylic resin (A) and a polyvinyl acetal resin (B) while shearing at a shear rate of 100 sec ⁻¹ or more. It includes a step of melt-kneading at a temperature of not lower than ° C and then cooling to a temperature of not higher than 120 ° C.
In a more preferred production method, when the methacrylic resin (A) and the polyvinyl acetal resin (B) are melt-kneaded at a resin temperature of 140 ° C. or higher, a shearing rate of 100 sec ⁻¹ or higher is applied, It is preferable to pass at least twice each of the step of setting the shear rate to 50 sec ⁻¹ or less.

In the method for producing an acrylic thermoplastic resin composition of the present invention, a methacrylic resin (A) and a polyvinyl acetal resin (B) are mixed into a single screw extruder, twin screw extruder, Banbury mixer, Brabender, open roll, kneader, etc. It is important to knead each component in a molten state using a known kneader. Among these kneaders, a large shearing force is obtained, the methacrylic resin (A) is easy to form a continuous phase, is excellent in productivity, and a shear is applied at a shear rate of 100 sec ⁻¹ or more. A twin screw extruder is preferred because it can easily create a process including at least twice each step of setting the speed to 50 sec ^-1 or less.

The resin temperature at the time of melt-kneading needs 140 degreeC or more, 140-270 degreeC is more preferable, 160-250 degreeC is especially preferable.
Shear applied to the thermoplastic resin composition at the time of melt-kneading, shear rate must be at 100 sec ^-1 or more, preferably 200 sec ^-1 or more.

  After melt-kneading, it is cooled to a temperature of 120 ° C. or lower. Cooling is preferably performed more rapidly than natural cooling by, for example, immersing the 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 compatible. Furthermore, the size of the dispersed phase becomes very small. The size of the dispersed phase is usually 1 μm or less, preferably 200 nm or less.

The acrylic thermoplastic resin composition of the present invention may be added to 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 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 thermoplastic resin composition. .
In addition, the said additive added to the acrylic thermoplastic resin composition of this invention may be added when manufacturing a thermoplastic resin composition, and may be added just before shaping | molding mentioned later.

  The acrylic thermoplastic resin composition of the present invention is used as, for example, a pellet-shaped or powder-shaped molding material. 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. The molded article of a preferred embodiment of the present invention has a change in haze before and after being left for 1500 hours under a temperature of 60 ° C. and a humidity of 90% (difference between haze before being left and haze after being left) is 1 Less than 0.0%.

  In particular, the acrylic thermoplastic resin composition of the present invention can be applied to a melt extrusion molding 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 calendar method, and an inflation method. Excellent toughness, improved toughness, excellent handleability, excellent balance between toughness and surface hardness and rigidity, stretched, bent, subjected to impacts and / or under prolonged heat and humidity conditions It is preferable in order to obtain a molded body that is not easily whitened when placed. In particular, in order to obtain a film-like molded body, the T-die method is preferably used from the viewpoint of economy.

  A preferable resin temperature for performing melt molding is 160 to 270 ° C. After molding, it is preferable to cool the molded body more rapidly than natural cooling. For example, it is preferable that the film-like molded body immediately after being extruded is brought into contact with a cooling roll and rapidly cooled. By performing such rapid cooling, a molded body in which the methacrylic resin (A) forms a continuous phase and the methacrylic resin (A) and the polyvinyl acetal resin (B) are partially compatible can be obtained. it can.

  The film of a preferred embodiment comprising the acrylic thermoplastic resin composition of the present invention has a surface having a JIS pencil hardness (thickness of 100 μm), preferably HB or harder, more preferably F or harder, Preferably it is H or harder than that. Since a film having a hard surface is hardly damaged, it is suitably used as a decorative and protective film for the surface of a molded product that requires design. Furthermore, the film of the preferred embodiment of the present invention has a change in haze before and after being left for 1500 hours under the conditions of a temperature of 60 ° C. and a humidity of 90% (difference between haze before being left and haze after being left), It is less than 1.0%.

  The film using the acrylic thermoplastic resin composition of the present invention may be a single layer film made of the acrylic thermoplastic resin composition of the present invention, or the acrylic thermoplastic resin composition of the present invention, It may be a laminated film (or laminated body) with other resin, a base material made of a non-wood fiber such as a wooden base material or kenaf.

In the laminated film, the acrylic thermoplastic resin composition of the present invention may be used for the inner layer of the film, a part thereof, or may be used for the outermost layer. There is no particular limitation on the number of laminated films.
The other resin used for the laminated film is preferably a transparent resin such as a methacrylic resin from the viewpoint of the design of the film.
The resin material used for the outermost layer is preferably one having high surface hardness and high weather resistance from the viewpoint that the film is not easily scratched and the design property lasts long. For example, a methacrylic resin or the acrylic thermoplastic resin of the present invention is preferable. Compositions are preferred.
Although the manufacturing method of a laminated film is not specifically limited, The method of manufacturing a multilayer film directly by the coextrusion method, the method of bonding the film produced with the single layer, etc. are mentioned.

  The acrylic thermoplastic resin composition of the present invention can be applied to various molded parts. Applications of the resin composition include, for example, billboard parts such as advertising towers, stand signboards, sleeve signboards, billboard signs, rooftop signs, and marking films; display parts such as showcases, partition plates, store displays; fluorescent lamp covers, Lighting parts such as mood lighting covers, lamp shades, light ceilings, light walls, and chandeliers; interior parts such as furniture, pendants, mirrors; Architectural parts such as roofs; aircraft windshields, pilot visors, motorcycles, motorboat windshields, bus shading plates, automotive side visors, rear visors, head wings, headlight covers, automotive interior components, bumper and other automotive exterior components Transportation equipment-related parts; nameplate for audio visuals, stereo cover, tele Electronic equipment parts such as protective masks, vending machines, mobile phones and personal computers; medical equipment parts such as incubators and X-ray parts; equipment-related parts such as machine covers, instrument covers, experimental devices, rulers, dials, observation windows; LCD protective plates, light guide plates, light guide films, Fresnel lenses, lenticular lenses, front parts of various displays, diffuser plates and other optical parts; road signs, guide plates, curved mirrors, sound barriers and other traffic related parts; Greenhouses, large aquariums, box aquariums, bathroom components, clock panels, bathtubs, sanitary, desk mats, game parts, toys, masks for facial protection when welding; PCs, mobile phones, furniture, vending machines, bathroom components Examples include surface materials.

  When the acrylic thermoplastic resin composition of the present invention is used, the balance between toughness, surface hardness and rigidity is excellent, and the tear strength is excellent, so that handling is easy, and when stretched, folded and / or impacted. Since it does not whiten when it is received, a molded article excellent in design can be obtained. When a film-like or sheet-like molded body made of the acrylic thermoplastic resin composition of the present invention is molded on a base material made of steel, plastic sheet, wood, glass, etc. by lamination, insert molding, in-mold molding, or the like The design properties of these base materials can be improved, and the base materials can be protected. Furthermore, by providing 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 design property is further improved. The protection can be increased. By coextruding the acrylic thermoplastic resin composition of the present invention and a base material made of steel, plastic, wood, glass or the like, the design of the base material can be improved. In addition, taking advantage of its excellent design, 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.

  Hereinafter, the present invention will be described more specifically with reference to examples, but 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.

Physical properties of molding materials such as thermoplastic resin compositions were evaluated according to the following methods.
(1) 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) as a detector. It measured using the differential refractive index detector RI-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 measurement was 1.0 ml / min. 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.

(2) Observation of elastic modulus, yield point elongation, elongation at break, toughness and whitening state in bending test The elastic modulus, yield point elongation and elongation at break in the bending test are in accordance with JIS K7171, manufactured by Shimadzu Corporation Using graph AG-5000B, a strain rate of 1 mm / min. Using a test piece of length 80 mm × width 10 mm × thickness 4 mm obtained by the injection molding method. Measured with
Toughness was evaluated by the energy required for the test piece to break.
The whitening state is carried out by visually observing the whitening state of the test piece at a bending strain of 20%. When the length of the whitened portion in the length direction of the test piece is 2 mm or more, x, 0.3 mm The above and less than 2 mm were evaluated as Δ, the less than 0.3 mm as ◯, and the one in which no whitening was observed was evaluated as ◎.

(3) Observation of elastic modulus, elongation at break, toughness and whitening state in tensile test The elastic modulus in the tensile test was obtained by injection molding using Autograph AG-5000B manufactured by Shimadzu Corporation according to JIS K7162. In addition, a strain rate of 1 mm / min. Measured with Observation of breaking elongation, toughness, and whitening state was performed according to JIS K7162, using an autograph AG-5000B manufactured by Shimadzu Corporation and using a 1A-type dumbbell-shaped test piece obtained by an injection molding method. min. It evaluated by measuring by. Toughness was evaluated by the energy required for the test piece to break.
The whitening state is performed by visually observing the whitening state of the test piece at a tensile strain of 10%, and the length of the whitened portion in the length direction of the test piece is 10 mm or more x 1 mm or more The case of less than 10 mm was evaluated as Δ, the case of less than 1 mm was evaluated as ○, and the one in which no whitening was observed was evaluated as ◎.

(4) Glass transition temperature (Tg)
The main dispersion peak temperature (Tg) of loss tangent (tan δ) is 60 mm long × width obtained by cutting a test piece obtained by injection molding using EXSTAR6000 DMS manufactured by SII Nano Technology Co., Ltd. In a bending mode (both-end beam measurement), a rectangular parallelepiped test piece having a thickness of 10 mm and a thickness of 4 mm is subjected to a sinusoidal vibration of 10 Hz, a heating rate of 3 ° C./min. It was measured by.

(5) Surface Hardness of Thermoplastic Resin Composition According to JIS K7202-2, Rockwell hardness (M scale) was measured using a 100 mm × 100 mm × 4 mm thick flat plate obtained by injection molding.

(6) Haze of thermoplastic resin composition According to JIS K7136, it measured with the test piece of thickness 4mm.

(7) Morphological observation with a transmission electron microscope After making an ultrathin section from a test piece obtained by injection molding using an ultramicrotome (Richert ULTRACUT-S manufactured by RICA), four polyvinyl acetal parts of a thermoplastic resin composition were obtained. Samples were prepared by electron staining with ruthenium oxide vapor. 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.

(8) Moist heat resistance A 100 mm × 100 mm × 4 mm thick flat plate obtained by injection molding was allowed to stand for 1500 hours under conditions of 60 ° C. and 95% RH. Wet heat resistance was evaluated by the difference in haze before and after the treatment (ΔH).

[Polyvinyl acetal resin]
An aldehyde compound and an acid catalyst (hydrochloric acid) were added to an aqueous solution in which the polyvinyl alcohol resin was dissolved, and the mixture was stirred to acetalize to precipitate the resin. Washed to pH = 6 according to known methods, then suspended in alkaline aqueous medium and worked up with stirring, washed again to pH = 7, volatiles to 1.0% The polyvinyl acetal resin shown in Table 1 was obtained by drying until it became.

The degree of acetalization of the polyvinyl acetal resin was determined by the following procedure.
First, in accordance with the method described in JIS K6728 (1977), the mass ratio (l ₀ ) of the vinyl alcohol unit and the mass ratio (m ₀ ) of the vinyl acetate unit were determined by the methods described below. The mass ratio (k ₀ ) was determined by k ₀ = 1−l ₀ −m ₀ .
_{Then, l = (l 0 /44.1)/(l 0} /44.1+m 0 /86.1+2k 0 / Mw (acetal) and _{m = (m 0 /44.1)/(l 0/} 44. 1 + m ₀ /86.1+2k ₀ / Mw (acetal) is obtained by calculation, and the ratio of vinyl acetal units (k = k ₍₁₎ + k ₍₂₎ +... + K _{( n)} ), and finally, the degree of acetalization (mol%) = {k ₍₁₎ + k ₍₂₎ +... + k _(n) } × 2 / {{k ₍₁₎ + k ₍₂₎ + ... + k _(n) } × 2 + l + m} × 100.
Here, Mw (acetal) is the molecular weight per acetalization unit. For example, in the case of polyvinyl butyral, Mw (acetal) = Mw (butyral) = 142.2.
In the case of coacetalization with butyraldehyde and other aldehydes, ¹ H-NMR or ¹³ C-NMR can be measured, and the degree of acetalization (mol%) can be calculated.

[How to find l ₀ and m ₀ ]
About 0.4 g of polyvinyl acetal resin is accurately weighed into a conical Erlenmeyer flask, dissolved by adding 10 ml of a mixed solution of pyridine / acetic anhydride (volume ratio 92/8) with a pipette, and attached with a cooler at a temperature of 50 ° C. On a water bath for 120 minutes. After cooling, 20 ml of dichloroethane was added and shaken well. Further, 50 ml of water was added, stoppered and shaken vigorously, and allowed to stand for 30 minutes. The acetic acid produced is titrated with N / 2 sodium hydroxide solution with phenolphthalein as an indicator until it turns pale red, and the titration is defined as a (ml). Separately, a blank test was performed, and the titration amount of the N / 2 sodium hydroxide solution required for this was defined as b (ml), and obtained by the following formula.
l ₀ = 2.2 × (ba) × F _l / (s _l × P _l )
In the formula, s _{1 is} the mass of the polyvinyl acetal resin, P ₁ is the pure content (%), and F ₁ is the titer of the N / 2 sodium hydroxide solution.
Also, weigh accurately about 0.4 g of polyvinyl acetal resin in a conical flask with a stirrup, add 25 ml of ethanol and dissolve at 85 ° C., add 5 ml of N / 10 sodium hydroxide solution while shaking well with a pipette, and cool. The vessel was attached and refluxed in a water bath at a temperature of 85 ° C. for 60 minutes. After cooling, 5 ml of N / 10 hydrochloric acid was added with a pipette, shaken well, and allowed to stand for 30 minutes. Excess hydrochloric acid was titrated with a N / 10 sodium hydroxide solution using phenolphthalein as an indicator until a slight red color was obtained, and the titer was c (ml). Separately, a blank test was carried out, and the titration amount of the N / 10 sodium hydroxide solution required for this was determined as d (ml), and obtained by the following formula.
m ₀ = 0.86 × (cd) × F _m / (s _m × P _m )
In the formula, s _{m is} the mass of the polyvinyl acetal resin, P _m is the pure content (%), and F _m is the titer of the N / 10 sodium hydroxide solution.

Example 1
90 parts of methacrylic resin (A-1: KARARAY PARAPET G, Mw = 100,000, Tg = 121 ° C.) and 10 parts of polyvinyl acetal resin (B-1) are mixed with a twin screw kneading extruder TEX manufactured by Nippon Steel. -44α (L / D = 40) was used for kneading at a cylinder temperature of 220 ° C. and a screw rotation speed of 200 rpm to obtain pellets of a thermoplastic resin composition. Maximum shear rate of the extruder is 300 sec ^-1, shear rates in the clearance large portion of the barrel and the screw elements were 45 sec ^-1. Screw in rotating speed of the used was a structure in which the shear shear and 45 sec ^-1 of 300 sec ^-1 is applied twice alternately. The resin temperature measured immediately before the die of the extruder at that time was 232 ° C.

The pellets of the obtained thermoplastic resin composition were injection-molded at a cylinder temperature of 240 ° C. using J50E2 manufactured by Nippon Steel, and a plastic JIS 1A type dumbbell-shaped test piece having a length of 80 mm × width of 10 mm × thickness of 4 mm. A rectangular parallelepiped test piece and a flat plate test piece of 100 mm × 100 mm × thickness 4 mm were obtained. Furthermore, the rectangular parallelepiped test piece of length 60mm * width 10mm * thickness 4mm was obtained by cut | disconnecting the rectangular parallelepiped test piece of length 80mm * width 10mm * thickness 4mm.
Using these test pieces, the elastic modulus, breaking elongation, toughness and whitening state of the sample in the bending test, the elastic modulus, breaking elongation, toughness and whitening state of the sample in the tensile test, the methacrylic resin of the thermoplastic resin composition The glass transition temperature (Tg _AP ), surface hardness, haze, and heat and humidity resistance due to (A) were measured, and the results are shown in Table 2. The morphology was observed and the results are shown in Table 2.

Comparative Example 1
Instead of the thermoplastic resin composition pellets used in Example 1, test pieces were produced in the same manner as in Example 1 using pellets consisting only of methacrylic resin (A-1: PARAPET G). The results are shown in Table 2.

Examples 2-7
A pellet of the thermoplastic resin composition was obtained in the same manner as in Example 1 except that the types and / or blending amounts of the methacrylic resin (A) and the polyvinyl acetal resin (B) were changed to the formulations shown in Table 2. A test piece was produced using the pellet. The results are shown in Table 2.

The maximum shear rate of the extruder in Example 2 was 300 sec ⁻¹ , and the resin temperature measured immediately before the die of the thermoplastic resin composition extruder was 233 ° C.
The maximum shear rate of the extruder in Example 3 was 300 sec ⁻¹ , and the resin temperature measured immediately before the die of the thermoplastic resin composition extruder was 232 ° C.
The maximum shear rate of the extruder in Example 4 was 300 sec ⁻¹ , and the resin temperature measured immediately before the die of the thermoplastic resin composition extruder was 231 ° C.
The maximum shear rate of the extruder in Example 5 was 300 sec ⁻¹ , and the resin temperature measured immediately before the die of the thermoplastic resin composition extruder was 230 ° C.
The maximum shear rate of the extruder in Example 6 was 300 sec ⁻¹ , and the resin temperature measured immediately before the die of the extruder for the thermoplastic resin composition was 229 ° C.
The maximum shear rate of the extruder in Example 7 was 300 sec ⁻¹ , and the resin temperature measured immediately before the die of the thermoplastic resin composition extruder was 230 ° C.

Example 8
Methacrylic resin (A-2: Mw = 45000, Mw / Mn = 2.5 resin obtained by radical polymerization of a monomer consisting of 92% by mass of methyl methacrylate and 8% by mass of methyl acrylate, Tg = 116 ° C. ) A pellet of the thermoplastic resin composition was obtained in the same manner as in Example 1 except that the formulation was changed to 75 parts and 25 parts of the polyvinyl acetal resin (B-1), and a test piece was produced using the pellets. did. The results are shown in Table 3. The maximum shear rate at that time was 300 sec ⁻¹ . The resin temperature measured immediately before the die of the extruder of the thermoplastic resin composition was 225 ° C.

Example 9
Methacrylic resin (A-3: resin of Mw = 15,000, Mw / Mn = 2.7 obtained by radical polymerization of a monomer consisting of 92% by mass of methyl methacrylate and 8% by mass of methyl acrylate, Tg = 116 ° C.) Except that the formulation was changed to 75 parts and polyvinyl acetal resin (B-1) 25 parts, a thermoplastic resin composition pellet was obtained in the same manner as in Example 1, and a test piece was further obtained using the pellet. Manufactured. The results are shown in Table 3. The maximum shear rate at that time was 300 sec ⁻¹ . At this time, the cylinder temperature when producing the pellets was set to 180 ° C. Moreover, the resin temperature measured just before the die | dye of the extruder of the thermoplastic resin composition was 225 degreeC.

Example 10
A pellet of the thermoplastic resin composition was obtained in the same manner as in Example 1 except that the formulation was changed to 75 parts of methacrylic resin (A-1) and 25 parts of polyvinyl acetal resin (B-4). A test piece was produced. The results are shown in Table 3. At that time, the maximum shear rate of the extruder was 300 sec ⁻¹ , and the resin temperature measured immediately before the die of the thermoplastic resin composition extruder was 231 ° C.

Example 11
Example 1 except that the formulation was changed to 75 parts of methacrylic resin (A-6: KURARAY PARAPET HR-F, Mw = 90,000, Tg = 135 ° C.) and 25 parts of polyvinyl acetal resin (B-1). In the same manner as above, pellets of the thermoplastic resin composition were obtained, and further test pieces were produced using the pellets. The results are shown in Table 3. The maximum shear rate of the extruder at that time was 300 sec ⁻¹ , and the resin temperature measured immediately before the die of the thermoplastic resin composition extruder was 236 ° C.

Comparative Example 2
Mw obtained by radical polymerization of a methacrylic resin (A-2: 92% by mass of methyl methacrylate and 8% by mass of methyl acrylate) instead of the pellets of the thermoplastic resin composition used in Example 1 = 45000, Mw / Mn = 2.5 resin), and a test piece was produced in the same manner as in Example 1 except that the temperature of injection molding and press molding was changed to 220 ° C. The evaluation results are shown in Table 3.

Comparative Example 3
Mw obtained by radical polymerization of a methacrylic resin (A-3: 92% by mass of methyl methacrylate and 8% by mass of methyl acrylate) instead of the pellets of the thermoplastic resin composition used in Example 1 = 15,000, Mw / Mn = 2.7 resin), and a test piece was produced in the same manner as in Example 1 except that the temperature of injection molding and press molding was changed to 200 ° C. The test piece was very brittle and physical properties could not be measured.

Comparative Example 4
Instead of pellets of the thermoplastic resin composition used in Example 1, a methacrylic resin (A-4: a soft polymer layer containing an alkyl acrylate unit and a hard polymer layer containing an alkyl methacrylate unit) A multi-layer structure polymer [1] consisting of a combination and having a hard polymer layer as the outermost layer [1] and a pellet composed of 16 parts by mass of a core-shell type particle-containing methacrylic resin composition comprising 84 parts by mass of a methacrylic resin) A test piece was produced in the same manner as in Example 1. The evaluation results are shown in Table 3.

Comparative Example 5
Instead of pellets of the thermoplastic resin composition used in Example 1, a methacrylic resin (A-5: a soft polymer layer containing an alkyl acrylate unit and a hard polymer layer containing an alkyl methacrylate unit) A multilayer structure polymer [1] consisting of a combination and having a hard polymer layer [1] 28 parts by mass, and a core-shell type particle-containing methacrylic resin composition comprising 72 parts by mass of a methacrylic resin) A test piece was produced in the same manner as in Example 1. The evaluation results are shown in Table 3.

Comparative Example 6
A pellet of the resin composition was obtained in the same manner as in Example 1 except that the formulation was changed to 20 parts of methacrylic resin (A-1: PARAPET G) and 80 parts of polyvinyl acetal resin (B-1). The test piece was manufactured using. The results are shown in Table 3. The maximum shear rate of the extruder at that time was 300 sec ⁻¹ , and the resin temperature measured immediately before the die of the thermoplastic resin composition extruder was 227 ° C.

The physical properties of the film were evaluated according to the following methods.
(1) Visible light transmittance of film Visible light calculated according to JIS R3106 by measuring the transmittance at a wavelength of 380 nm to 780 nm of a 100 μm thick film using a spectrophotometer U-4100 manufactured by Hitachi High-Technologies Corporation. The transmittance was measured.

(2) Measurement of haze of film According to JIS K7136, it measured with the 100-micrometer-thick test film.

(3) Elastic modulus, elongation at break, and toughness in film tensile test A plastic JIS1A type dumbbell-shaped test film was punched from a film having a thickness of 100 μm so as to be stretched in the MD direction at the time of a tensile test. Using AG-5000B, the strain rate is 5 mm / min. The test was conducted to measure the elastic modulus, elongation at break, and toughness of the test film. Toughness was evaluated by the energy required for the test film to break.

(4) Tear strength of the film Using an autograph AG-5000B manufactured by Shimadzu Corporation, an angle-less test film without cut in accordance with the JIS K6252 standard was punched, and the tensile speed was 5 mm / min. The maximum tear strength (unit: N / mm) in terms of thickness when the angle type test film without incision was torn was evaluated. The measurement was performed with a film having a thickness of 100 μm.

(5) Surface hardness of film The pencil hardness of a film having a thickness of 100 μm was measured according to JIS K5400.

(6) Observation of the whitening state of the film When a film having a thickness of 100 μm is folded 180 ° so as to be creased in the TD direction, according to a visual evaluation, the folded portion is not whitened at all. Evaluation was made with Δ for the part whitened, and × for the whole bent part whitened.

(7) Morphological observation of film by transmission electron microscope After making an ultrathin section from a film using an ultramicrotome (Reichert ULTRACUT-S manufactured by RICA), the polyvinyl acetal part of the thermoplastic resin composition was vaporized with ruthenium tetroxide. A sample was prepared by electron staining. 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.
(8) Moisture and heat resistance of the film A film having a thickness of 100 μm was treated for 1500 hours under the conditions of 60 ° C. and 95% RH, and the moisture and heat resistance was evaluated by the difference in haze before and after the treatment (ΔH).

Example 12
The pellets produced in Example 1 were extruded from a T-die having a width of 500 mm using a GT-40 manufactured by Plastics Engineering Laboratory under the conditions of a cylinder temperature and a T-die temperature of 220 ° C., thereby forming a thermoplastic resin having a thickness of 100 μm. A film of the composition was obtained. Table 4 shows the results of visible light transmittance, haze, tensile modulus, tensile elongation at break, toughness, tear strength, surface hardness, whitening state, heat and humidity resistance, and morphology observation of the obtained film.

Examples 13-18
A film was produced in the same manner as in Example 12 except that the pellets produced in Examples 2 to 7 were used instead of the pellets produced in Example 1, and the visible light transmittance of the obtained film was obtained. Table 4 shows the results of haze, tensile modulus, tensile elongation at break, toughness, tear strength, surface hardness, whitening state, moist heat resistance, and morphology observation.

Comparative Example 7
A film was prepared in the same manner as in Example 12 except that a pellet made of only a methacrylic resin (A-1: PARAPET G) was used instead of the pellet produced in Example 1, and various measurements and observations were made. went. The results are shown in Table 4. The whitened state could not be evaluated because the film broke when bent 180 °.

Examples 19 and 20
A film was produced in the same manner as in Example 12 except that the pellets produced in Examples 10 and 11 were used instead of the pellets produced in Example 1, and the visible light transmittance of the obtained film was obtained. Table 5 shows the results of haze, tensile modulus, tensile elongation at break, toughness, tear strength, surface hardness, whitening state, heat and humidity resistance, and morphology observation.

Comparative Example 8
An attempt was made to produce a film in the same manner as in Example 12 except that instead of the pellet produced in Example 1, a pellet consisting only of the methacrylic resin (A-2) used in Comparative Example 2 was used. However, it was very brittle and a film-like molded product could not be obtained.

Comparative Example 9
Instead of the pellets produced in Example 1, pellets consisting only of the methacrylic resin (A-3: Mw = 15,000) used in Comparative Example 3 were used, and the temperature of the cylinder and T die of the extruder was 200 ° C. An attempt was made to produce a film in the same manner as in Example 12 except that the resin was changed to. However, the resin was very brittle and a film-like molded product could not be obtained.

Comparative Examples 10-12
A film was produced in the same manner as in Example 12 except that the pellets used in Comparative Examples 4 to 6 were used instead of the pellets produced in Example 1, and various measurements and observations of the obtained film were performed. went. The results are shown in Table 5.

Comparative Example 13
0.9 g of methacrylic resin (A-1) and 0.3 g of polyvinyl acetal resin (B-1) are dissolved in 10.8 g of tetrahydrofuran and stirred at 25 ° C., mass ratio: methacrylic resin (A-1) / Polyvinyl acetal resin (B-1) = 75/25 mixed solution was obtained. This mixed solution was poured onto a film made of polyethylene terephthalate with the bottom divided into 10 cm × 10 cm, air-dried at 25 ° C., and then vacuum-dried to obtain a film having a tetrahydrofuran content of 0.03%. The thickness of the obtained film was 104 μm. The resulting film glass transition temperature due to the methacrylic resin (A) of (Tg _AP) a Tg _AP = 121 ° C. was measured, was a Tg _AP = Tg _A. Table 5 shows the results of the visible light transmittance, haze, tensile modulus, tensile elongation at break, toughness, tear strength, surface hardness, moist heat resistance, and morphology observation of the obtained film. The whitened state could not be evaluated because the film broke when bent 180 °.

Comparative Example 14
4.5 g of finely pulverized methacrylic resin (A-1) and 1.5 g of finely pulverized polyvinyl acetal resin (B-1) were mixed and sandwiched between parallel plates with a radius of 20 mm heated to 230 ° C. While the plate was fixed, only the upper plate was rotated at 15 rpm and a constant shear was applied for 10 minutes. At this time, the interval between the parallel plates was 4 mm, and there was no gap between the parallel plate and the resin. Under this condition, the shear rate applied to the resin is calculated to be 2π × (15/60) / (4/20) ≈7.9 (sec ⁻¹ ). The resin composition thus melt-kneaded was hot-pressed to obtain a film having a thickness of 105 μm. The resulting film glass transition temperature due to the methacrylic resin (A) of (Tg _AP) a Tg _AP = 121 ° C. was measured, was a Tg _AP = Tg _A.
Table 5 shows the results of the visible light transmittance, haze, tensile modulus, tensile elongation at break, toughness, tear strength, surface hardness, moist heat resistance, and morphology observation of the obtained film. The whitened state could not be evaluated because the film broke when bent 180 °.

Claims (16)

An acrylic thermoplastic resin composition containing a methacrylic resin (A) and a polyvinyl acetal resin (B),
At least the methacrylic resin (A) forms a continuous phase,
Acrylic glass transition temperature Tg _AP due to methacrylic resin (A) of the glass transition temperature of the thermoplastic resin composition, the methacrylic resin (A) alone glass transition temperature at (Tg _A) and the polyvinyl acetal resin ( B) thermoplastic acrylic resin composition indicates a value between the glass transition temperature (Tg _B) alone.   The acrylic thermoplastic resin composition according to claim 1, wherein a mass ratio (A) / (B) of the methacrylic resin (A) and the polyvinyl acetal resin (B) is 99/1 to 51/49.   The acrylic thermoplastic resin composition according to claim 1 or 2, wherein the methacrylic resin (A) has a weight average molecular weight (Mw) of 40000 or more.   The acrylic thermoplastic resin composition according to any one of claims 1 to 3, wherein the degree of acetalization of the polyvinyl acetal resin (B) is 55 to 83 mol%.   The polyvinyl acetal resin (B) is obtained by performing a drying treatment after adjusting the pH of the slurry obtained by (co) acetalizing the polyvinyl alcohol resin to 6-8. An acrylic thermoplastic resin composition according to claim 1.   The acrylic thermoplastic resin composition according to any one of claims 1 to 5, wherein the polyvinyl acetal resin (B) is polyvinyl butyral.   According to JIS K7171, a strain rate of 1 mm / min. Using a test piece of length 80 mm × width 10 mm × thickness 4 mm. In accordance with the flexural modulus at the time of the test and the JIS K7162, a strain rate of 1 mm / min. The acrylic thermoplastic resin composition according to any one of claims 1 to 6, wherein at least one of the tensile elastic moduli when tested at 2 is 2 GPa or more.   According to JIS K7171, a strain rate of 1 mm / min. Using a test piece of length 80 mm × width 10 mm × thickness 4 mm. The acrylic thermoplastic resin composition according to claim 1, which has a stress yield point when subjected to a bending test. A step of melting and kneading the methacrylic resin (A) and the polyvinyl acetal resin (B) at a resin temperature of 140 ° C. or higher while applying shear at a shear rate of 100 sec ⁻¹ or higher, and then cooling to 120 ° C. or lower; The manufacturing method of the acrylic thermoplastic resin composition in any one of Claims 1-8. When melt-kneading the methacrylic resin (A) and the polyvinyl acetal resin (B) at a resin temperature of 140 ° C. or higher, a step of applying a shear at a shear rate of 100 sec ⁻¹ or more and a shear rate of 50 sec ⁻¹ The method for producing an acrylic thermoplastic resin composition according to claim 9, wherein each of the following steps is performed at least twice.   The acrylic thermoplastic resin composition obtained by the manufacturing method of Claim 9 or 10.   The molded object which consists of an acryl-type thermoplastic resin composition in any one of Claims 1-8 and Claim 11.   The molded product according to claim 12, wherein the change in haze before and after being left for 1500 hours under conditions of a temperature of 60 ° C and a humidity of 90% is less than 1.0%.   The film which consists of an acryl-type thermoplastic resin composition in any one of Claims 1-8 and Claim 11.   The film according to claim 14, wherein the polyvinyl acetal resin (B) is polyvinyl butyral, and the surface has a JIS pencil hardness of F or higher.   The film according to claim 14 or 15, wherein a change in haze before and after being left for 1500 hours under conditions of a temperature of 60 ° C and a humidity of 90% is less than 1.0%.