JP7586771B2 - Solidified powder containing acrylic crosslinked rubber particles, method for producing same, resin composition, and molded article - Google Patents

Description

The present invention relates to a coagulated powder containing acrylic crosslinked rubber particles, a method for producing the same, a resin composition, and a molded article.

Methacrylic resin has excellent transparency, and molded articles made from it have a beautiful appearance and weather resistance, making them used in a variety of applications, including display components such as lighting fixtures and signs, optical components such as display parts, interior components, building components, electronic and electrical components, and medical components. However, molded articles made from methacrylic resin have insufficient impact resistance, and are prone to cracking and chipping when subjected to stress from being dropped, hit, or vibrated.

To improve the impact strength of methacrylic resin, a suitable method is to add multilayered polymer particles that have a rubber component layer inside and a thermoplastic resin component layer on the outermost layer. This method is currently the most widely used industrial method.

However, in conventional methacrylic impact-resistant resins in which multilayered polymer particles are blended in a methacrylic resin, although impact resistance is improved, particle aggregates are observed on the surface of the molded product obtained from the resin as bumps, resulting in appearance defects accompanied by unevenness. Patent Document 1 discloses a manufacturing method in which a multilayered polymer obtained by emulsion polymerization and a rigid thermoplastic polymer are uniformly mixed in a latex state, and then solidified to obtain an impact modifier that has good dispersibility when melt-mixed with a rigid methacrylic resin, and can significantly improve the occurrence of bumps. However, since the impact modifier contains a rigid thermoplastic polymer, the proportion of the soft polymer layer is small, and the impact resistance relative to the amount added is poor. Patent Document 2 discloses a manufacturing method in which a multilayered polymer is dispersed in an organic solvent, and then an aqueous phase is separated to obtain aggregates, and an organic solvent is added to the aggregates, and the resulting dispersion is mixed with a polymerizable organic compound, thereby obtaining a good dispersion state of the multilayered polymer, but the resin that can be added is limited to polymerizable organic compounds having reactive groups such as epoxy resins.

Patent No. 3145864 WO2005/028546

The object of the present invention is to provide a coagulated powder containing acrylic crosslinked rubber particles that has excellent dispersibility in a matrix resin (base resin) and excellent impact resistance.

In order to achieve the above object, the present invention provides a coagulated powder containing acrylic crosslinked rubber particles that satisfies the following conditions, a method for producing the same, and a resin composition and molded article each containing the coagulated powder.
[1]
A coagulated powder comprising an inner layer containing a crosslinked rubber containing acrylic acid alkyl ester units, and an outermost layer made of a thermoplastic resin containing methyl methacrylate units and graft-bonded to the inner layer, the thermoplastic resin of the outermost layer having a glass transition temperature of 60 to 85°C, a weight average molecular weight of 40,000 to 80,000, and an average particle size of 0.08 to 0.3 μm, the coagulated powder comprising acrylic crosslinked rubber particles,
When 60 parts by mass of a methyl methacrylate resin having a melt flow rate of 8±1 g/10 min at 230 ° C. and 37.3 N and 40 parts by mass of the coagulated powder are melt-kneaded at a temperature of 230 ° C. using a kneading/extrusion molding evaluation test device equipped with a consumption shear energy measuring device,
The solidified powder, in a 0.1 mass % acetone dispersion of a melt-kneaded composition of the solidified powder and the methyl methacrylate-based resin, wherein the consumed shear energy E required until the acrylic-based crosslinked rubber particles are unimodally dispersed to have a dispersed particle diameter of 1 μm or less is 180 MJ/m3 ^{or less} .
[2]
The coagulated powder according to [1], wherein the average particle size of the acrylic crosslinked rubber particles is 0.2 to 0.3 μm.
[3]
A polymerization step of producing a latex containing acrylic crosslinked rubber particles by an emulsion polymerization method;
aggregating the latex at 35 to 65° C.;
The method for producing a coagulated powder according to [1] or [2], further comprising a granulation step of granulating at 100 to 130° C.
[4]
A resin composition comprising the coagulated powder according to [1] or [2] and a matrix resin.
[5]
The resin composition according to [4], wherein the thermoplastic resin is a methacrylic resin.
[6]
A molded article comprising the resin composition according to [4] or [5].

The present invention can provide a coagulated powder containing acrylic crosslinked rubber particles that has excellent dispersibility in a matrix resin (base resin) such as a thermoplastic resin and has excellent impact resistance.

4 shows the results of measuring the dispersed particle size distribution of the coagulated powder in acetone.

<Acrylic crosslinked rubber particles>
The acrylic crosslinked rubber particles constituting the coagulated powder of the present invention are particles containing an acrylic crosslinked rubber polymer obtained by emulsion polymerization, and are preferably multi-layered rubber particles containing an outermost layer made of a thermoplastic polymer (P) and a crosslinked rubber polymer (Q) in contact with and covering the outermost layer. Examples of the multi-layered rubber particles include particles having a two-layer structure (Q-P) of a core of a crosslinked rubber polymer (Q) and an outer shell (outermost layer) of a thermoplastic polymer (P), a three-layer structure (R-Q-P) of a core of a crosslinked polymer (R) and an inner shell of a crosslinked rubber polymer (Q) and an outer shell (outermost layer) of a thermoplastic polymer (P), and a four-layer structure (Q-R-Q-P) of a core of a crosslinked rubber polymer (Q) and a first inner shell of a crosslinked polymer (R) and a second inner shell of a crosslinked rubber polymer (Q) and an outer shell (outermost layer) of a thermoplastic polymer (P).

The mass ratio of the layer other than the outermost layer in the acrylic crosslinked rubber particle (hereinafter, the layer other than the outermost layer may be referred to as the "inner layer", for example, the above Q, R+Q, and Q+R+Q each correspond to an inner layer) to the outermost layer is preferably 60/40 to 95/5, more preferably 70/30 to 90/10, for inner layer/outermost layer. The proportion of the layer containing the crosslinked rubber polymer (Q) in the inner layer is preferably 20 to 70 mass%, more preferably 30 to 50 mass%.

The average particle size of the acrylic crosslinked rubber particles is 0.08 to 0.3 μm, preferably 0.2 to 0.3 μm. When acrylic crosslinked rubber particles having an average particle size within this range, particularly an average particle size of 0.2 to 0.3 μm, are used, toughness can be exhibited even with a small amount of incorporation, and therefore the rigidity and surface hardness of the molded product are not impaired. Note that the average particle size in this specification is the average value in the volume-based particle size distribution measured by a light scattering method (volume average particle size), or the average particle size measured from an electron microscope photograph.
In one embodiment of the present invention, the glass transition temperature of the thermoplastic resin of the outermost layer is 60 to 85° C., preferably 65 to 80° C. If the glass transition temperature of the thermoplastic resin is within this range, it is preferable in that the shear energy consumed during melt-kneading with the matrix resin is reduced.
In another embodiment of the present invention, the weight average molecular weight (Mw) of the thermoplastic resin of the outermost layer is 40,000 to 80,000, and preferably 50,000 to 70,000. If the weight average molecular weight of the thermoplastic resin is within this range, it is preferable in terms of impact resistance and dispersibility.

The thermoplastic polymer (P) constituting the outermost layer is preferably a polymer containing a methacrylic acid alkyl ester unit having an alkyl group having 1 to 8 carbon atoms (hereinafter, sometimes referred to as "methacrylic acid _C1-8 alkyl ester") and, if necessary, a monofunctional monomer unit other than the methacrylic acid alkyl ester. It is preferable that the thermoplastic polymer (P) does not contain a polyfunctional monomer unit.

The amount of methacrylic acid alkyl ester units having an alkyl group with 1 to 8 carbon atoms constituting the thermoplastic polymer (P) is preferably 75 to 100% by mass, more preferably 80 to 95% by mass, based on the mass of the thermoplastic polymer (P).

As the methacrylic acid alkyl ester having an alkyl group having 1 to 8 carbon atoms (hereinafter, sometimes referred to as methacrylic acid _C1-8 alkyl ester), for example, methyl methacrylate (MMA) is preferable.

The amount of monofunctional monomer units other than the methacrylic acid _C1-8 alkyl ester constituting the thermoplastic polymer (P) is preferably 0 to 25 mass%, more preferably 5 to 20 mass%, based on the mass of the thermoplastic polymer (P).
Preferred examples of the monofunctional monomer other than the methacrylic acid _C1-8 alkyl ester include acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and propyl acrylate, and aromatic vinyl compounds such as styrene.

The outermost layer may be a single layer made of one type of thermoplastic polymer (P), or may be a multi-layer made of two or more types of thermoplastic polymers (P).

In one preferred embodiment of the present invention, the inner layer has an intermediate layer made of a crosslinked rubber polymer (Q) and a core made of a crosslinked polymer (R) that is in contact with and covered by the intermediate layer (inner layer = R + Q).

The crosslinked polymer (R) consists of methyl methacrylate units, monofunctional monomer units other than methyl methacrylate, and polyfunctional monomer units.

The amount of methyl methacrylate units constituting the crosslinked polymer (R) is preferably 40 to 98.5% by mass, more preferably 80 to 95% by mass, based on the mass of the crosslinked polymer (R).

The amount of the monofunctional monomer units other than methyl methacrylate constituting the crosslinked polymer (R) is 1 to 59.5% by mass, preferably 5 to 20% by mass, based on the mass of the crosslinked polymer (R).
Preferred examples of the monofunctional monomer other than methyl methacrylate include acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and propyl acrylate, and aromatic vinyl compounds such as styrene.

The amount of the polyfunctional monomer unit constituting the crosslinked polymer (R) is preferably 0.05 to 0.4% by mass, more preferably 0.1 to 0.3% by mass, based on the mass of the crosslinked polymer (R).

The amount of the crosslinked polymer (R) is preferably 5 to 40% by mass, more preferably 7 to 35% by mass, and even more preferably 10 to 30% by mass, relative to the amount of the multilayered rubber particles.

The crosslinked rubber polymer (Q) is composed of acrylate ester units having an alkyl group with 1 to 8 carbon atoms, monofunctional monomer units other than acrylate esters, and polyfunctional monomer units.

The content of the acrylic ester unit having an alkyl group having 1 to 8 carbon atoms in the crosslinked rubber polymer (Q) is preferably 10 to 90% by mass, more preferably 20 to 85% by mass, based on the mass of the crosslinked rubber polymer (Q).
The content of the monofunctional monomer units other than the acrylic acid ester in the crosslinked rubber polymer (Q) is preferably 10 to 90% by mass, more preferably 15 to 80% by mass, based on the mass of the crosslinked rubber polymer (Q).

The amount of the polyfunctional monomer unit in the crosslinked rubber polymer (Q) is preferably 0.01 to 3 mass %, more preferably 0.1 to 2 mass %, based on the mass of the crosslinked rubber polymer (Q).

Examples of acrylic acid esters used in the thermoplastic polymer (P), the crosslinked rubber polymer (Q), and the crosslinked polymer (R) include alkyl acrylic acid esters such as methyl acrylate (MA), ethyl acrylate, n-propyl acrylate, n-butyl acrylate (BA), s-butyl acrylate, t-butyl acrylate, n-butylmethyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, and n-octyl acrylate. These acrylic acid esters may be used alone or in combination of two or more. Of these, methyl acrylate and/or n-butyl acrylate are preferred.

Examples of the polyfunctional monomer unit used in the crosslinked rubber polymer (Q) and the crosslinked polymer (R) include ethylene glycol dimethacrylate, propylene glycol dimethacrylate, triethylene glycol dimethacrylate, hexanediol dimethacrylate, ethylene glycol diacrylate, propylene glycol diacrylate, triethylene glycol diacrylate, allyl methacrylate (ALMA), and triallyl isocyanurate.
The monofunctional monomer units other than methyl methacrylate in the crosslinked polymer (R) and the monofunctional monomer units other than acrylic acid esters in the crosslinked rubber polymer (Q) may be any vinyl monomer that can be copolymerized with a methacrylic acid ester or an acrylic acid ester, and examples thereof include aromatic vinyl monomers such as styrene, p-methylstyrene, o-methylstyrene, and vinylnaphthalene, unsaturated nitrile monomers such as acrylonitrile, olefin monomers such as ethylene and propylene, halogenated vinyl monomers such as vinyl chloride, vinylidene chloride, and vinylidene fluoride, unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, and maleic anhydride, and maleimide monomers such as vinyl acetate, N-propylmaleimide, N-cyclohexylmaleimide, and N-o-chlorophenylmaleimide, and these compounds may be used alone or in combination of two or more.

<Polymerization step>
The latex of the acrylic crosslinked rubber particles, which comprises an outermost layer composed of a thermoplastic polymer (P), an inner shell composed of a crosslinked rubber polymer (Q) in contact with and covering the outermost layer, and a core composed of a crosslinked polymer (R) as required, can be produced in accordance with a conventional method by polymerizing each of them in multiple stages using a monomer mixture, a polymerization initiator, an emulsifier, etc.
The polymerization initiator used in each polymerization is not particularly limited. Examples of the polymerization initiator include water-soluble inorganic initiators such as potassium persulfate and ammonium persulfate; redox initiators obtained by combining an inorganic initiator with a sulfite or thiosulfate; and redox initiators obtained by combining an organic peroxide with a ferrous salt or sodium sulfoxylate. The polymerization initiator may be added to the reaction system all at once at the start of polymerization, or may be added to the reaction system in portions at the start of polymerization and during polymerization, taking into account the reaction rate. The amount of the polymerization initiator used may be appropriately set so that the average particle size of the granular material contained in the acrylic crosslinked rubber particles falls within the above-mentioned range.

The emulsifier used in each polymerization is not particularly limited. Examples of emulsifiers include anionic emulsifiers such as long-chain alkyl sulfonates, sulfosuccinic acid alkyl ester salts, and alkylbenzene sulfonates; nonionic emulsifiers such as polyoxyethylene alkyl ethers and polyoxyethylene nonylphenyl ether; nonionic and anionic emulsifiers such as polyoxyethylene nonylphenyl ether sulfates such as sodium polyoxyethylene nonylphenyl ether sulfate, polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene alkyl ether sulfate, and alkyl ether carboxylates such as sodium polyoxyethylene tridecyl ether acetate. The amount of emulsifier used can be appropriately set so that the average particle size of the granular material contained in the acrylic crosslinked rubber particles is within the above-mentioned range.

A preferred method for producing the coagulated powder of the present invention includes a polymerization step of producing a latex containing acrylic crosslinked rubber particles by emulsion polymerization, an aggregation step of aggregating the latex at 35 to 65°C to obtain a slurry, and a granulation step of granulating the slurry at 100 to 130°C.

The production of coagulated powder from the latex containing the acrylic crosslinked rubber particles of the present invention can be carried out by the freeze coagulation method, the salting-out coagulation method, the acid precipitation coagulation method, etc. Among these, the salting-out coagulation method is preferred because it is possible to adjust the coagulation force of the coagulated powder and to continuously produce a high-quality coagulated product.

<Aggregation step>
The aggregation process is a reaction that causes slow aggregation, in which the emulsified latex and the coagulant solution are mixed in a heated state, and the aggregation is allowed to proceed at a slow rate in order to improve the dispersibility of the acrylic crosslinked rubber particles during the subsequent melt-kneading.

The coagulant that can be used in the present invention may be an aqueous solution of an inorganic acid or its salt, or an organic acid or its salt, that has the property of being able to coagulate or solidify the emulsion polymerized latex.

Specific examples of the inorganic acid solution, inorganic acid salt solution, organic acid solution, or organic acid salt solution include, for example, alkali metal halides such as sodium chloride, potassium chloride, lithium chloride, sodium bromide, potassium bromide, lithium bromide, potassium iodide, and sodium iodide; alkali metal sulfates such as potassium sulfate and sodium sulfate; ammonium sulfate; ammonium chloride; alkali metal nitrates such as sodium nitrate and potassium nitrate; calcium chloride, ferrous sulfate, magnesium sulfate, calcium acetate, zinc sulfate, copper sulfate, barium chloride, ferrous chloride, ferric chloride, magnesium chloride, ferric sulfate, aluminum sulfate, potassium alum, and iron alum, and other inorganic salt solutions, either alone or in combination of two or more kinds. Among these, aqueous solutions of monovalent or divalent inorganic acid salts such as sodium chloride, potassium chloride, sodium sulfate, ammonium chloride, calcium chloride, magnesium chloride, magnesium sulfate, barium chloride, and calcium acetate can be preferably used. There is no particular restriction on the method of adding the coagulant, and it can be added all at once, in portions, or continuously.

The polymer concentration of the emulsified latex in the aggregation step is preferably 5 to 25% by mass, more preferably 7.5 to 22.5% by mass, and even more preferably 10 to 20% by mass. The lower the polymer concentration of the emulsified latex, the more difficult it is for aggregation to proceed, and the higher the concentration, the easier it is to aggregate, but it tends to be difficult to control due to the high viscosity.

The concentration of the coagulant added in the coagulation step is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 7.5 parts by mass, and even more preferably 1.0 to 7.0 parts by mass, per 100 parts by mass of the polymer in the emulsified latex. If the concentration of the coagulant added is low, coagulation will be difficult to proceed, and the higher the concentration, the easier it will be to proceed, but the hot water or boiling water whitening resistance of the resulting coagulated material will tend to deteriorate.

The residence time in the aggregation step is preferably 0.25 to 2.0 hours, more preferably 0.5 to 1.75 hours, and even more preferably 0.75 to 1.6 hours. The shorter the residence time, the less aggregation there will be and the smaller the particle size of the resulting coagulated product will be. The longer the residence time, the easier it will be for aggregation to proceed, but the hot water or boiling water whitening resistance of the resulting coagulated product will tend to deteriorate.

<Granulation process>
In the granulation step, the slurry obtained in the first solidification (aggregation step) is further heated to reduce the number of fine particles that do not completely aggregate and to increase the bulk density of the aggregate.

The residence time in the granulation step is preferably 0.5 to 3 hours, more preferably 0.75 to 2.75 hours, and even more preferably 1.0 to 2.5 hours. The shorter the residence time, the more insufficient the granulation will be and the smaller the particle size of the resulting coagulated product will be. The longer the residence time, the easier it will be to granulate, but the resulting coagulated product will tend to have poor resistance to whitening in hot water or boiling water.

The washing and dehydration of the slurry can be carried out, for example, using a filter press, belt press, Ginner centrifuge, or screw decanter centrifuge. From the viewpoint of productivity and washing efficiency, it is preferable to use a screw decanter centrifuge. It is preferable to wash and dehydrate the slurry at least twice. The more times washing and dehydration are carried out, the lower the remaining amount of water-soluble components. However, from the viewpoint of productivity, it is preferable to wash and dehydrate three times or less.

The moisture content of the coagulum after dehydration is preferably 5 to 50% by mass, more preferably 5 to 45% by mass, and even more preferably 5 to 40% by mass. The higher the moisture content, the less sufficient the drying can be, and the more difficult it becomes to obtain a coagulum with a suitable moisture content after drying.
The turbidity of the wastewater discharged during dehydration is preferably not more than 1000, more preferably not more than 700, and even more preferably not more than 400. High turbidity of the wastewater indicates insufficient solid-liquid separation, which not only reduces the product yield but also causes problems such as clogging of the strainer of the discharge pump, making stable operation difficult.

The coagulated material is dried so that the moisture content is preferably less than 0.2% by mass, more preferably less than 0.1% by mass. The higher the moisture content, the more likely it is that an ester hydrolysis reaction will occur in the acrylic crosslinked rubber particles during melt extrusion molding, resulting in the formation of carboxyl groups in the molecular chains.

The solidified powder of the present invention is defined as a series of melt-kneaded compositions obtained by melt-kneading 60 parts by mass of a methyl methacrylate resin having a melt flow rate of 8±1 g/10 min according to JIS K7210 at 230° C. and 37.3 N and 40 parts by mass of the solidified powder at a temperature of 230° C. and 40 rpm using a kneading/extrusion molding evaluation tester equipped with a consumption shear energy measuring device, and sampling every minute. The methyl methacrylate resin has a weight average molecular weight in the range of 70,000 to 120,000, and a mass ratio of methyl methacrylate units:methyl acrylate units of 90:10 to 100:0. The series of melt-kneaded compositions are each stirred in acetone at a ratio of 0.1% by mass for 2 hours at room temperature, and the acetone dispersion in which the soluble components are dissolved and the insoluble components are dispersed is measured for particle size distribution using a laser diffraction/scattering particle size distribution measuring device. Samples with short melt-kneading times have multimodal or broad particle size distributions, whereas samples with advanced melt-kneading times have a unimodal distribution.
In the solidified powder of the present invention, in a series of melt-kneaded compositions sampled every minute, the consumed shear energy E required for the acrylic crosslinked rubber particles to initially form a unimodal distribution having a dispersed particle size of 1 μm or less is 180 MJ/m3 ^{or less} , preferably 150 MJ/m3 ^or less.
The solidified powder of the present invention, in which the consumed shear energy E is equal to or less than the upper limit, has excellent dispersibility of the acrylic crosslinked rubber particles when melt-kneaded into a methacrylic resin, and the composition with the methacrylic resin has reduced agglomeration defects and is excellent in impact resistance.

<Resin Composition>
Examples of the matrix resin contained in the resin composition of the present invention include methacrylic resins which are homopolymers or copolymers mainly composed of methacrylic acid esters such as polymethyl methacrylate, olefin resins such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, and polynorbornene, styrene resins such as ethylene ionomers, polystyrene, styrene-maleic anhydride copolymers, high impact polystyrene, AS resins, ABS resins, AES resins, AAS resins, ACS resins, and MBS resins, and methyl methacrylate-styrene resins such as styrene- ... Examples of the matrix resin include ethylene copolymers, ester resins such as polyethylene terephthalate and polybutylene terephthalate, amide resins such as nylon 6, nylon 66, and polyamide elastomers, polyphenylene sulfide, polyether ether ketone, polysulfone, polyphenylene oxide, polyimide, polyetherimide, polycarbonate, polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, polyacetal, and phenoxy resins, with methacrylic resins being preferred. One or more types of matrix resins can be used.

The resin composition of the present invention may contain various additives as necessary. Examples of additives include antioxidants, heat deterioration inhibitors, ultraviolet absorbers, light stabilizers, lubricants, release agents, polymer processing aids, antistatic agents, flame retardants, dyes/pigments, light diffusing agents, matting agents, anti-sticking agents, impact resistance modifiers, and phosphors. The content of these additives can be appropriately set within a range that does not impair the effects of the present invention. For example, it is preferable that the content of the antioxidant is 0.01 to 1 part by mass, the content of the ultraviolet absorber is 0.01 to 3 parts by mass, the content of the light stabilizer is 0.01 to 3 parts by mass, the content of the lubricant is 0.01 to 3 parts by mass, the content of the dye/pigment is 0.01 to 3 parts by mass, and the anti-sticking agent is 0.001 to 1 part by mass, relative to 100 parts by mass of the resin composition. Other additives can also be added in the range of 0.01 to 3 parts by mass.

Antioxidants are effective in preventing oxidative degradation of resins by themselves in the presence of oxygen. Examples include phosphorus-based antioxidants, phenol-based antioxidants, sulfur-based antioxidants, and amine-based antioxidants. Among these, from the viewpoint of preventing degradation of optical properties due to coloring, phosphorus-based antioxidants and phenol-based antioxidants are preferred, and it is more preferred to use a phenol-based antioxidant alone or in combination with a phosphorus-based antioxidant. When using a phosphorus-based antioxidant and a phenol-based antioxidant in combination, it is preferable to use the phosphorus-based antioxidant/phenol-based antioxidant in a mass ratio of 0.2/1 to 2/1, and more preferably 0.5/1 to 1/1.

Preferred phosphorus-based antioxidants include 2,2-methylenebis(4,6-di-t-butylphenyl)octylphosphite (ADEKA CORPORATION's "ADEKA STAB HP-10"), tris(2,4-di-t-butylphenyl)phosphite (BASF Japan Ltd.'s "IRGAFOS168"), and 3,9-bis(2,6-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (ADEKA CORPORATION's "ADEKA STAB PEP-36"), etc.

Preferred phenol-based antioxidants include pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] ("IRGANOX 1010" manufactured by BASF Japan Ltd.) and octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate ("IRGANOX 1076" manufactured by BASF Japan Ltd.).
Preferred sulfur-based antioxidants include dilauryl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, pentaerythritol tetrakis(3-laurylthiopropionate), and the like.
As the amine-based antioxidant, octylated diphenylamine and the like are preferred.

Thermal degradation inhibitors are capable of preventing thermal degradation of resins by capturing polymer radicals that are generated when the resin is exposed to high temperatures under substantially oxygen-free conditions. Preferred examples of thermal degradation inhibitors include 2-t-butyl-6-(3'-t-butyl-5'-methyl-hydroxybenzyl)-4-methylphenyl acrylate (Sumitomo Chemical Co., Ltd.'s "Sumilizer GM") and 2,4-di-t-amyl-6-(3',5'-di-t-amyl-2'-hydroxy-α-methylbenzyl)phenyl acrylate (Sumitomo Chemical Co., Ltd.'s "Sumilizer GS")

An ultraviolet absorber is a compound that is said to have the ability to absorb ultraviolet light and to have the function of converting mainly light energy into heat energy. Examples of ultraviolet absorbers include benzophenones, benzotriazoles, triazines, benzoates, salicylates, cyanoacrylates, oxalic acid anilides, malonic acid esters, and formamidines. Among these, benzotriazoles and triazines are preferred. One or more types of ultraviolet absorbers can be used.

Light stabilizers are compounds that are said to have the function of capturing radicals that are generated mainly by oxidation due to light. Suitable light stabilizers include hindered amines such as compounds with a 2,2,6,6-tetraalkylpiperidine skeleton. For example, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate ("ADEKA STAB LA-77Y" manufactured by ADEKA Corporation) can be mentioned.

Lubricants are compounds that are said to have the effect of improving releasability and processability by adjusting the slip between the resin and the metal surface and preventing adhesion or sticking. Examples include higher alcohols, hydrocarbons, fatty acids, fatty acid metal salts, fatty amides, and fatty acid esters. Among them, from the viewpoint of compatibility with the resin composition of the present invention, aliphatic monohydric alcohols and aliphatic amides having 12 to 18 carbon atoms are preferred, and aliphatic amides are more preferred. Fatty amides are classified into saturated aliphatic amides and unsaturated aliphatic amides, and unsaturated aliphatic amides are more preferred because they are expected to have a slip effect due to anti-adhesion. Examples of unsaturated aliphatic amides include N,N'-ethylenebisoleamide ("Slipax O" manufactured by Nippon Kasei Co., Ltd.) and N,N'-dioleyl adipamide ("Slipax ZOA" manufactured by Nippon Kasei Co., Ltd.).

Examples of the release agent include higher alcohols such as cetyl alcohol and stearyl alcohol; and higher fatty acid esters of glycerin such as stearic acid monoglyceride and stearic acid diglyceride. In the present invention, it is preferable to use a higher alcohol and a glycerin fatty acid monoester in combination as the release agent. When a higher alcohol and a glycerin fatty acid monoester are used in combination, the ratio is not particularly limited, but the amount of higher alcohol used: the amount of glycerin fatty acid monoester used is preferably 2.5:1 to 3.5:1, and more preferably 2.8:1 to 3.2:1, by mass ratio.
The polymer processing aid is a compound that is effective in achieving thickness accuracy and thinning when molding a resin composition. The polymer processing aid is usually a polymer particle having a particle size of 0.05 to 0.5 μm that can be produced by emulsion polymerization.

Examples of antistatic agents include alkyl sulfonates such as sodium heptyl sulfonate, sodium octyl sulfonate, sodium nonyl sulfonate, sodium decyl sulfonate, sodium dodecyl sulfonate, sodium cetyl sulfonate, sodium octadecyl sulfonate, sodium diheptyl sulfonate, potassium heptyl sulfonate, potassium octyl sulfonate, potassium nonyl sulfonate, potassium decyl sulfonate, potassium dodecyl sulfonate, potassium cetyl sulfonate, potassium octadecyl sulfonate, potassium diheptyl sulfonate, lithium heptyl sulfonate, lithium octyl sulfonate, lithium nonyl sulfonate, lithium decyl sulfonate, lithium dodecyl sulfonate, lithium cetyl sulfonate, lithium octadecyl sulfonate, and lithium diheptyl sulfonate.

Flame retardants include metal hydrates having hydroxyl groups or crystal water such as magnesium hydroxide, aluminum hydroxide, hydrated aluminum silicate, hydrated magnesium silicate, and hydrotalcite, phosphate compounds such as polyamine phosphate and phosphate esters, and silicon compounds, and are preferably phosphate ester-based flame retardants such as trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, dimethylethyl phosphate, methyldibutyl phosphate, ethyldipropyl phosphate, and hydroxyphenyldiphenyl phosphate.

Examples of dyes and pigments include red organic pigments such as Para Red, Fire Red, Pyrazolone Red, Thioindigo Red, and Perylene Red; blue organic pigments such as Cyanine Blue and Indanthrene Blue; and green organic pigments such as Cyanine Green and Naphthol Green. One or more of these may be used.
Examples of the light diffusing agent and the matting agent include glass particles, polysiloxane-based crosslinked particles, crosslinked polymer particles, talc, calcium carbonate, barium sulfate, etc. The copolymer of the present invention preferably does not contain an acid generator.

Examples of the anti-sticking agent include fatty acids such as stearic acid and palmitic acid; fatty acid metal salts such as calcium stearate, zinc stearate, magnesium stearate, potassium palmitate, and sodium palmitate; waxes such as polyethylene wax, polypropylene wax, and montanic acid wax; low molecular weight polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene; acrylic resin powder; polyorganosiloxane such as dimethylpolysiloxane; amide resin powders such as octadecylamine, alkyl phosphate, fatty acid ester, ethylene bisstearylamide, and other fluororesin powders such as tetrafluoroethylene resin, molybdenum disulfide powder, silicone resin powder, silicone rubber powder, and silica.
Examples of impact resistance modifiers include core-shell type modifiers that contain a diene rubber as a core layer component; modifiers that encapsulate a plurality of rubber particles; and the like.
Examples of fluorescent substances include fluorescent pigments, fluorescent dyes, fluorescent white dyes, fluorescent brighteners, and fluorescent bleaches.

When the resin composition of the present invention contains a matrix resin and/or an additive, the additive may be added during polymerization of the matrix resin and/or the acrylic crosslinked rubber particles, or may be added when mixing with the matrix resin and/or the acrylic crosslinked rubber particles, or may be added after mixing with the matrix resin and/or the acrylic crosslinked rubber particles.

The resin composition of the present invention can be molded using molding methods and molding equipment commonly used for matrix resins. For example, molded products can be produced by molding methods that involve heating and melting, such as injection molding, extrusion molding, compression molding, blow molding, calendar molding, and vacuum molding, and solution casting methods.

The resin composition of the present invention is also useful as a film, and can be well processed, for example, by the usual melt extrusion methods such as the inflation method and T-die extrusion method, or the calendar method, and further the solution casting method. If necessary, it is also possible to obtain a film with better surface properties by simultaneously contacting both sides of the film with a roll or metal belt, particularly by simultaneously contacting both sides with a roll or metal belt heated to a temperature equal to or higher than the glass transition temperature. In addition, it is also possible to modify the film by lamination molding or biaxial stretching depending on the purpose.

The film obtained from the resin composition of the present invention can be laminated to metals, plastics, etc. Examples of lamination methods include wet lamination, in which an adhesive is applied to a metal plate such as a steel plate, and then a film is placed on the metal plate and dried to bond them together, as well as dry lamination, extrusion lamination, and hot melt lamination.

Methods for laminating a film onto a plastic part include film insert molding, in which the film is placed inside a mold and then filled with resin by injection molding, laminate injection press molding, and film in-mold molding, in which the film is preformed, then placed inside a mold and then filled with resin by injection molding.

The resin composition of the present invention and the molded product containing the same can be used as a member for various applications.Specific applications include, for example, signboard parts and marking films; display parts; lighting parts; interior parts; building parts; transport-related parts such as automobile side visors, rear visors, head wings, headlight covers, sunroofs, glazing, automobile interior parts, and automobile exterior parts such as bumpers; electronic equipment parts; medical equipment parts; machine-related parts; liquid crystal protection plates, light guide plates, light guide films, Fresnel lenses, lenticular lenses, front panels of various displays, diffusion plates, and other optical parts; transportation-related parts; and other various surface materials.
On the other hand, laminated products of films obtained from the resin composition of the present invention can be used for automobile interior and exterior materials, daily necessities, wallpaper, paint replacement applications, housings for furniture and electric devices, housings for office automation equipment such as facsimiles, flooring materials, parts for electric or electronic devices, bathroom equipment, etc.

The following describes manufacturing examples and examples of the present invention, as well as comparative examples.

[Evaluation items and evaluation methods]
The evaluation items and evaluation methods in the Production Examples, Examples, and Comparative Examples are as follows.
(Weight average molecular weight (Mw))
The weight average molecular weight (Mw) of the resin was determined by the GPC method. Tetrahydrofuran was used as the eluent. As the column, two TSKgel SuperMultipore HZM-M columns manufactured by Tosoh Corporation and a SuperHZ4000 were connected in series. As the GPC device, Tosoh Corporation's HLC-8320 (product number) equipped with a differential refractive index detector (RI detector) was used. A sample solution was prepared by dissolving 4 mg of the resin to be measured in 5 mL of tetrahydrofuran. The temperature of the column oven was set to 40°C, and 20 μL of the sample solution was injected into the device at an eluent flow rate of 0.35 mL/min to measure the chromatogram. Ten standard polystyrene points with molecular weights in the range of 400 to 5,000,000 were measured by GPC, and a calibration curve showing the relationship between retention time and molecular weight was created. The Mw of the resin to be measured was determined based on this calibration curve.

(Volume average particle size)
For the latex containing acrylic crosslinked rubber particles, the volume average particle size was determined by a light scattering method using a laser diffraction/scattering type particle size distribution measuring device LA-950V2 manufactured by Horiba, Ltd.

(shear energy consumed)
60 parts by mass of methyl methacrylate resin (Parapet G manufactured by Kuraray Co., Ltd.) having a melt flow rate of 8 g/10 min at 230 ° C. and 37.3 N was kneaded for 3 minutes at 230 ° C. and 80 rpm using a Sigma Mixer in a kneading/extrusion molding evaluation tester equipped with a consumption shear energy measuring device (Labo Plastomill 4C150 manufactured by Toyo Seiki Co., Ltd.), and then 40 parts by mass of the solidified powder was added and further kneaded at 40 rpm. During kneading, samples were taken every minute to obtain melt-kneaded compositions with different consumption shear energy. 0.10 parts by mass of each of the obtained melt-kneaded compositions was dissolved in 100 parts by mass of acetone for 2 hours, and the resulting dispersion was measured by a light scattering method using a laser diffraction/scattering type particle size distribution measuring device LA-950V2 manufactured by Horiba, Ltd. to measure the volume average dispersed particle size of the acrylic crosslinked rubber particles dispersed in the methacrylic resin. When the particle size was within 1 μm or less and a single distribution peak (unimodal) appeared, it was considered to be dispersed into primary particles, and the shear energy consumed by the resin composition was adopted as the shear energy consumed by the solidified powder.

(Charpy impact value)
The impact value (with notch) of the press-molded sample was measured at a temperature of 23° C. and a relative humidity of 50% by a method in accordance with JIS-K7111. Five measurements were performed, and the average value was used as the Charpy impact value.

(Number of defects)
The pellets of the acrylic resin composition obtained in the examples or comparative examples were extruded at a cylinder temperature of 240 to 250°C and a 150 mm wide T-die temperature of 260°C using an extruder ME-20/26V2 and a winder CR-8 attached to a polymer quality inspection device manufactured by OCS Co., Ltd., and the film was wound on a cooling roll at a speed of 4.2 m/min to obtain a film having a thickness of 30 to 70 mm. The obtained film was measured for defects of 40 μm or more using the polymer quality inspection device FSA-100, and the number per ^m2 was used as the number of different bumps (number of bump defects).

(Production Example 1)
In a reactor equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, a monomer inlet tube and a reflux condenser, 750 parts by mass of ion-exchanged water, 0.14 parts by mass of sodium polyoxyethylene tridecyl ether acetate and 0.1 parts by mass of sodium carbonate were charged, and the inside of the reactor was fully replaced with nitrogen gas. Then, the inside temperature was set to 80°C. 0.10 parts by mass of potassium persulfate was added thereto and stirred for 5 minutes. 262.5 parts by mass of a monomer mixture consisting of 93.8% by mass of methyl methacrylate (MMA), 6.0% by mass of methyl acrylate (MA) and 0.2% by mass of allyl methacrylate (ALMA) was continuously dripped into the mixture over a period of 45 minutes. After the dripping was completed, the polymerization reaction was continued for another 60 minutes so that the polymerization conversion rate was 98% or more (first layer (R)).
Next, 0.10 parts by mass of potassium persulfate was added to the reactor and stirred for 5 minutes. Then, 337.5 parts by mass of a monomer mixture consisting of 80.6% by mass of butyl acrylate (BA), 17.4% by mass of styrene (St) and 2% by mass of allyl methacrylate (ALMA) were continuously dripped over 60 minutes. After the dripping was completed, the polymerization reaction was carried out for another 80 minutes so that the polymerization conversion rate was 98% or more (first layer (R) + second layer (Q)). Next, 0.10 parts by mass of potassium persulfate was added to the reactor and stirred for 5 minutes. Then, 150 parts by mass of a monomer mixture consisting of 80.0% by mass of methyl methacrylate (MMA) and 20.0% by mass of methyl acrylate (MA) and 0.3 parts by mass of n-octyl mercaptan were continuously dripped over 25 minutes. After the dripping was completed, the polymerization reaction was carried out for another 60 minutes so that the polymerization conversion rate was 98% or more. By the above operations, a latex containing acrylic crosslinked rubber particles was obtained (first layer (R) + second layer (Q) + third layer (P)). The volume average particle diameter of the acrylic crosslinked rubber particles in the latex was 0.26 μm.

(Production Example 2)
A latex containing a crosslinked rubber polymer was obtained in the same manner as in Production Example 1 for the first and second layers.
Next, 0.10 parts by mass of potassium persulfate was added to the reactor and stirred for 5 minutes. Then, 150 parts by mass of a monomer mixture consisting of 94.0% by mass of methyl methacrylate and 6.0% by mass of methyl acrylate and 0.3 parts by mass of n-octyl mercaptan were continuously dropped over 25 minutes. After the dropping was completed, the polymerization reaction was carried out for another 60 minutes so that the polymerization conversion rate was 98% or more. By the above operations, a latex containing acrylic crosslinked rubber particles (three-layer structure: R-Q-P) was obtained. The volume average particle diameter of the acrylic crosslinked rubber particles in the latex was 0.23 μm.

(Production Example 3)
A latex containing a crosslinked rubber polymer was obtained in the same manner as in Production Example 1 for the first and second layers.
Next, 0.10 parts by mass of potassium persulfate was added to the reactor and stirred for 5 minutes. Then, 150 parts by mass of a monomer mixture consisting of 94.0% by mass of methyl methacrylate and 6.0% by mass of methyl acrylate and 1.125 parts by mass of n-octyl mercaptan were continuously dropped over 25 minutes. After the dropping was completed, the polymerization reaction was carried out for another 60 minutes so that the polymerization conversion rate was 98% or more. By the above operations, a latex containing acrylic crosslinked rubber particles (three-layer structure: R-Q-P) was obtained. The volume average particle diameter of the acrylic crosslinked rubber particles in the latex was 0.29 μm.

(Production Example 4)
For the first and second layers, a latex containing a crosslinked rubber polymer was obtained in the same manner as in Production Example 1.
Next, 0.10 parts by mass of potassium persulfate was added to the reactor and stirred for 5 minutes. Then, 150 parts by mass of a monomer mixture consisting of 86.0% by mass of methyl methacrylate and 14.0% by mass of butyl acrylate and 0.3% by mass of n-octyl mercaptan were continuously dropped over 25 minutes. After the dropwise addition, the polymerization reaction was continued for another 60 minutes so that the polymerization conversion rate was 98% or more. By the above operations, a latex containing acrylic crosslinked rubber particles (three-layer structure: R-Q-P) was obtained. The volume average particle diameter of the acrylic crosslinked rubber particles in the latex was 0.29 μm.

(Production Example 5)
For the first and second layers, a latex containing a crosslinked rubber polymer was obtained in the same manner as in Production Example 1.
Next, 0.10 parts by mass of potassium persulfate was added to the reactor and stirred for 5 minutes. Then, 150 parts by mass of a monomer mixture consisting of 86.0% by mass of methyl methacrylate and 14.0% by mass of butyl acrylate and 1.125 parts by mass of n-octyl mercaptan were continuously dropped over 25 minutes. After the dropping was completed, the polymerization reaction was carried out for another 60 minutes so that the polymerization conversion rate was 98% or more. By the above operations, a latex containing acrylic crosslinked rubber particles (three-layer structure: R-Q-P) was obtained. The volume average particle diameter of the acrylic crosslinked rubber particles in the latex was 0.29 μm.

[Example 1]
The latex obtained in Production Example 1 was coagulated under the following conditions. 484.8 parts of ion-exchanged water and 5.25 parts of magnesium sulfate were added to 210 parts of latex, and the liquid temperature was raised to 40°C while stirring. Stirring was continued for 1.1 hours while maintaining the liquid temperature at 40°C to obtain an aggregated slurry. The slurry was further heated to 115°C and stirred for 1.6 hours while maintaining the temperature to obtain a granulated slurry. The obtained granulated slurry was washed and dehydrated using a screw decanter centrifuge, and dried to obtain a coagulated powder. The volume average particle size of the coagulated powder was 239 μm.
40 parts by mass of the obtained solidified powder and 60 parts by mass of a methacrylic resin were melt-kneaded in a Φ40 mm single screw extruder at a cylinder temperature of 170 to 235° C. Thereafter, the molten resin composition was extruded to obtain a pellet-shaped acrylic resin composition, and the number of defects was measured by the above-mentioned method.
In addition, 40 parts by mass of the obtained coagulated powder and 60 parts by mass of methacrylic resin were kneaded at 230°C for 3 minutes in a Labo Plastomill (4C150 manufactured by Toyo Seiki Seisakusho Co., Ltd.) to obtain an acrylic resin composition, and the dispersed particle size distribution in acetone shown in Figure 1 was measured. Furthermore, a molded product having a thickness of 3 mm was obtained by hot press molding at 230°C for 4 minutes and 30 seconds, and the Charpy impact value was measured. The physical property evaluation results are shown in Table 2.

[Examples 2 to 4]
Coagulated powders were obtained in the same manner as in Example 1, except that the temperature and acrylic crosslinked rubber particles were changed as shown in Table 2. In each Example, a molded product was obtained using the obtained coagulated powder in the same manner as in Example 1. The physical property evaluation results for each Example are shown in Table 2.

[Comparative Examples 1 to 6]
A coagulated powder was obtained in the same manner as in Example 1, except that the temperature and the acrylic crosslinked rubber particles and dispersion particles were changed to those shown in Table 3. In each comparative example, a molded product was obtained using the obtained coagulated powder in the same manner as in Example 1. The physical property evaluation results in each comparative example are shown in Table 3. In addition, 40 parts by mass of the coagulated powder obtained in Comparative Example 1 and 60 parts by mass of a methacrylic resin were kneaded in a Labo Plastomill at 230°C for 3 minutes to obtain an acrylic resin composition, and the dispersed particle size distribution in acetone shown in Figure 1 was measured.

The molded articles obtained in Examples 1 to 4, which were made from the coagulated powder containing the acrylic crosslinked rubber particles of the present invention, had good dispersibility and impact resistance.

In contrast, the molded products obtained in Comparative Examples 1 and 2, which were made from a coagulated powder containing acrylic cross-linked rubber particles with a high third layer glass transition temperature, had a greater number of defects and poor impact strength compared to the Examples.

The molded product obtained in Comparative Example 3, which was made from a coagulated powder containing acrylic crosslinked rubber particles produced by increasing the coagulation temperature in the process of obtaining the coagulated powder, had a greater number of defects and poorer impact strength than the examples.

The molded product obtained in Comparative Example 4, in which the outermost layer was made of a coagulated powder containing low molecular weight acrylic crosslinked rubber particles, had poor impact strength compared to the examples.

The molded product obtained in Comparative Example 5, which was made from a coagulated powder containing acrylic crosslinked rubber particles produced by lowering the molecular weight of the outermost layer and increasing the granulation temperature in the process of obtaining the coagulated powder, had a greater number of defects and poorer impact strength than the examples.

The molded product obtained in Comparative Example 6, which was made of a coagulated powder containing acrylic crosslinked rubber particles obtained by adding dispersing particles, had poor impact strength compared to the Examples due to a decrease in the overall rubber content.

Claims (6)

A coagulated powder comprising an inner layer containing a crosslinked rubber containing acrylic acid alkyl ester units, and an outermost layer made of a thermoplastic resin containing methyl methacrylate units and graft-bonded to the inner layer, the thermoplastic resin of the outermost layer having a glass transition temperature of 60 to 85°C, a weight average molecular weight of 40,000 to 80,000, and an average particle size of 0.08 to 0.3 μm, the coagulated powder comprising acrylic crosslinked rubber particles,
When 60 parts by mass of a methyl methacrylate resin having a melt flow rate of 8±1 g/10 min at 230 ° C. and 37.3 N and 40 parts by mass of the coagulated powder are melt-kneaded at a temperature of 230 ° C. using a kneading/extrusion molding evaluation test device equipped with a consumption shear energy measuring device,
The solidified powder, in a 0.1 mass % acetone dispersion of a melt-kneaded composition of the solidified powder and the methyl methacrylate resin, wherein the consumed shear energy E required until the acrylic crosslinked rubber particles are unimodally dispersed to have a dispersed particle diameter of 1 μm or less is 180 MJ/m3 ^or less. The coagulated powder according to claim 1, wherein the average particle size of the acrylic crosslinked rubber particles is 0.2 to 0.3 μm. A polymerization step of producing a latex containing acrylic crosslinked rubber particles by an emulsion polymerization method;
aggregating the latex at 35 to 65° C.;
The method for producing a solidified powder according to claim 1 or 2, further comprising a granulation step of granulating at 100 to 130°C. A resin composition comprising the coagulated powder according to claim 1 or 2 and a matrix resin. The resin composition according to claim 4, wherein the matrix resin is a methacrylic resin. A molded article comprising the resin composition according to claim 4 or 5.