JP2000248142A - Resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition that is excellent in the temperature dependence of haze and color tone appearance, fluidity, and moldability. SOLUTION: The resin composition comprises an acrylic copolymer (A) of an acrylic multi-layered structure, which includes an innermost layer polymer (a1) formed by polymerizing 100 parts by weight of monomers containing not less than 40% of 1-4C alkyl methacrylates, and a crosslinking agent and a graft-crossing agent, each present in an amount of 0.1 to 5 parts, an intermediate layer polymer (a2) formed by polymerizing 100 parts of monomers composed of 70 to 90% of 1-8C alkyl methacrylates and 10 to 30% of aromatic vinyl monomers, and a crosslinking agent and a graft-crossing agent, each present in an amount of 0.1 to 5 parts, in the presence of the polymer (a1), and an outermost layer polymer (a3) formed by polymerizing a mixture of not less than 50% of 1-4C alkyl methacrylates in the presence of the polymers (a1) and (a2), and has an average particle size of 0.05 to 0.09 μm and a graft ratio of 10 to 29%, and wherein the content of an alkaline earth metal is not higher than 350 ppm, and also a resin composition comprises the above-mentioned resin composition and a methacrylic resin (B) of not less than 50% of MMA wherein the content of an alkaline earth metal is not higher than 350 ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition containing an acrylic multi-layer copolymer or methacrylic resin as a main component. This resin composition is useful, for example, as a material for lamp lenses and the like.

[0002]

2. Description of the Related Art It has been known that the use of an elastomer component such as a diene rubber or an acrylic rubber is effective for improving the solvent resistance and impact resistance of a methacrylic resin for outdoor use. . Of these, diene rubbers have poor weather resistance, and acrylic-based multi-layer graft rubbers are frequently used, and many proposals have been made.

[0003] For example, Japanese Patent Publication No. 58-1694 proposes an acrylic multi-layer graft rubber having a hard-soft-hard three-layer basic structure and an intermediate layer between each layer. Further, Japanese Patent Publication No. Sho 62-41241 proposes an acrylic multi-layer graft rubber having a four-layer structure of soft-hard-soft-hard. further,
JP-A-57-85843, JP-A-5-32045
No. 7, JP-A-7-286084 discloses a hard-soft-hard three-layer structure in which the particle size and composition, the particle size and composition and the graft ratio, the rubber layer thickness and the graft ratio are specified. Has been proposed.

However, these acrylic multi-layer graft rubbers are intended to improve the solvent resistance and the like while maintaining the properties such as the appearance and weather resistance of the methacrylic resin. When the environmental temperature changes, the resin composition obtained by blending has a haze due to a difference in refractive index between the methacrylic resin and the acrylic multilayer graft rubber and an influence of impurities contained in the acrylic multilayer graft rubber. However, there is a defect that the appearance such as yellowish color changes with temperature, that is, the so-called color appearance has a large temperature dependency.

[0005] As a means for commercializing a methacrylic resin composition containing an acrylic-based multi-layer graft rubber, a method such as injection molding or sheeting is generally used. For example, melting characteristics have been required. But,
When the acrylic multi-layered graft rubber is blended with the hard acrylic resin, the fluidity of the molten resin is reduced, and as a result, there is a problem that the molding temperature range during the processing is narrowed and the processability is deteriorated. Further, when the fluidity decreases, there is a problem that molding distortion tends to remain during molding, and the solvent crack resistance due to the molding distortion deteriorates.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior arts, and maintains the haze and the temperature of the color appearance while maintaining the transparency inherent in methacrylic resin. Resin composition that has low dependence, can be used in a wide environment, has excellent solvent crack resistance, has good fluidity, and has excellent processability that can support various molding technologies The purpose is to provide things.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above-mentioned object, and as a result, have found that an acrylic-based multilayer structure having a specific composition and structure as an acrylic-based rubber compounded in an acrylic resin. By using a polymer and reducing the content of alkaline earth metal to a specific value or less, it was found that excellent results were obtained, and the present invention was completed.

That is, the present invention provides an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms in an amount of 40 to 100% by weight;
Alkyl acrylate having 1 to 8 carbon atoms in the alkyl group 0
~ 60% by weight and other copolymerizable monomers 0
100% by weight of a monomer or monomer mixture consisting of
Parts by weight, 0.1 to 5 parts by weight of a cross-linking agent, and 0.1 to 5 parts by weight of a graft crosslinking agent, in the presence of an innermost layer polymer (a1) and an innermost layer polymer (a1) The alkyl acrylate having 1 to 8 carbon atoms in the alkyl group is 70 to 90.
100 parts by weight of a monomer mixture consisting of 10 to 30% by weight of an aromatic vinyl monomer and 0 to 20% by weight of another copolymerizable monomer, and 0.1 to 5% by weight of a crosslinking agent. Part and a graft crosslinking agent in an amount of from 0.1 to 5 parts by weight, and in the presence of an interlayer polymer (a2), an innermost layer polymer (a1) and an interlayer polymer (a2), Alkyl methacrylate 50 having 1 to 4 carbon atoms in the alkyl group
To 100% by weight, 0 to 50% by weight of an alkyl acrylate having 1 to 8 carbon atoms in an alkyl group, and 0 to 20% by weight of another copolymerizable monomer. An acrylic multi-layer copolymer (A) having an average particle diameter of 0.05 to 0.09 μm and a graft ratio of 10 to 29%, comprising an outermost layer polymer (a3) obtained by polymerization; 350p of earth metal content
pm or less.

Further, the present invention comprises the above resin composition and a methacrylic resin (B) containing methyl methacrylate as a main component, and having an alkaline earth metal content of 350 p.
pm or less.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

The acrylic multi-layer copolymer (A) contained in the resin composition of the present invention comprises an innermost layer polymer (a1), an intermediate layer polymer (a2) and an outermost layer polymer (a3), Basically, a three-layer copolymer is mainly used.

The innermost layer polymer (a1) is an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms, 40 to 100% by weight (preferably 80 to 100% by weight), and an alkyl group having 1 to 8 carbon atoms. Acrylate 0-60% by weight
(Preferably 0 to 20% by weight), and 100 parts by weight of a monomer or monomer mixture composed of 0 to 20% by weight of another copolymerizable monomer, and 0.1 to 5 parts by weight of a crosslinking agent. And 0.1 to 5 parts by weight of a graft crosslinking agent. These components may be polymerized in a mixture state.

If the composition in the production of the innermost layer polymer (a1) deviates from the above range, the transparency and the temperature dependence of the color appearance are inferior. In particular, when used as a vehicle lamp lens material at a high temperature, transparency becomes poor.

In the innermost layer polymer (a1), examples of the alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and n-butyl methacrylate. Further, the carbon number of the alkyl group is 1 to
Examples of the alkyl acrylate 8 include methyl acrylate, ethyl acrylate, i-propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and the like. Further, as other copolymerizable monomers, for example, styrene, α-methylstyrene, aromatic vinyl monomers such as vinyl toluene, phenyl methacrylate, cyclohexyl methacrylate,
Benzyl methacrylate and the like. Among these, it is preferable to use an aromatic vinyl monomer, and it is more preferable that the used amount is 3 to 7% by weight.

In the innermost layer polymer (a1), examples of the crosslinking agent include diesters of acrylic acid or methacrylic acid such as glycols such as ethylene glycol, 1,3-butylene glycol, triethylene glycol, and polyethylene glycol; trimethylol Various polyfunctional crosslinking agents such as propane triacrylate, triallyl isocyanurate, and pentaerythritol tetraacrylate are exemplified. Examples of the grafting agent include various polyfunctional grafting agents such as allyl, methallyl, and crotyl esters such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid.

The cross-linking agent has substantially the same reactivity of a plurality of functional groups, and mainly forms cross-links in the layer. On the other hand, the graft-linking agent has a function of effectively forming a chemical bond between layers due to a difference in reactivity between at least one of a plurality of functional groups of the graft-crossing agent and the other.

The amount of the cross-linking agent and the graft-crossing agent used in the innermost layer polymer (a1) is within the above range, but the ratio of the cross-linking agent / graft-crossing agent is 1/10 by weight.
To 20/1, preferably 1/1 to 10
/ 1 is more preferable.

In the presence of the innermost layer polymer (a1), the intermediate layer polymer (a2) contains 70 to 90% by weight (preferably 80 to 80% by weight) of an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms.
To 85% by weight), 10 to 30% by weight of an aromatic vinyl monomer
(Preferably 15 to 20% by weight), 100 parts by weight of a monomer mixture composed of 0 to 20% by weight of other copolymerizable monomers, and 0.1 to 5 parts by weight of a crosslinking agent (preferably 1 to 20% by weight). To 3 parts by weight) and 0.1 to 5 parts by weight (preferably 1 to 3 parts by weight) of a graft crosslinking agent. These components may be polymerized in a mixture state.

Specific examples of each monomer in the intermediate layer polymer (a2) are the same as those described above for the innermost layer polymer (a1). The ratio of the crosslinking agent / graft crosslinking agent in the intermediate layer polymer (a2) was 1 / weight ratio.
It is preferably in the range of 30 to 10/1, and 1/20
More preferably, it is in the range of 2/1.

The outermost layer polymer (a3) is prepared by preparing an alkyl methacrylate 50 having an alkyl group having 1 to 4 carbon atoms in the presence of the innermost layer polymer (a1) and the intermediate layer polymer (a2).
To 100% by weight (preferably 80 to 99% by weight, more preferably 90 to 97% by weight), and the carbon number of the alkyl group is 1
0 to 50% by weight (preferably 1 to 10% by weight, more preferably 3 to 10% by weight) of alkyl acrylate of
Further, it can be obtained by polymerizing a monomer or monomer mixture composed of 0 to 20% by weight of other copolymerizable monomers.

Specific examples of each monomer in the outermost layer polymer (a3) are the same as those described above for the innermost layer polymer (a1).

In polymerizing the outermost layer polymer (a3), it is desirable to control the graft ratio using a chain transfer agent. Adjustment of the graft ratio by the chain transfer agent has the effect of improving the compatibility with the matrix resin and further improving the fluidity of the resin composition of the present invention.

As the chain transfer agent, alkyl mercaptan is preferred. Specific examples thereof include n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, and t-dodecyl mercaptan. The use amount of the chain transfer agent is preferably in the range of 0.1 to 5 parts by weight based on 100 parts by weight of the monomer mixture used for forming the outermost layer polymer (a3).

The weight ratio of each layer of the acrylic multi-layer copolymer (A) (the weight ratio of the total monomers used in each layer) is not particularly limited. In terms of maintaining the balance of transparency at normal temperature and high temperature, solvent resistance, mechanical properties, and the like, the total amount of the innermost layer polymer (a1) and the intermediate layer polymer (a2) is 100 parts by weight. When the innermost layer polymer (a
1) is 5 to 50 parts by weight, and the intermediate layer polymer (a2) is 50 to 50 parts by weight.
It is preferably 95 parts by weight, and 25 to 400 parts by weight of the outermost layer polymer (a3) based on 100 parts by weight of the total of the innermost layer polymer (a1) and the intermediate layer polymer (a2). Is preferred.

The acrylic multi-layer copolymer (A) can be produced by a conventionally known emulsion polymerization method. An example of this manufacturing method will be described below.

After adding deionized water and, if necessary, an emulsifier to the reaction vessel, a monomer or a monomer mixture for constituting the innermost layer polymer (a1) is added and polymerized. In the presence of the innermost layer polymer (a1), a monomer mixture for forming the intermediate layer polymer (a2) is added and polymerized to form a shell around the innermost layer polymer (a1). . Subsequently, in the presence of the particles, a monomer or a monomer mixture for constituting the outermost layer polymer (a3) is added and polymerized to obtain a desired acrylic multilayer copolymer (A). Can be obtained.

The polymerization initiator used here is not particularly limited. Examples of the radical polymerization initiator include benzoyl peroxide, cumene hydroperoxide, t-
Peroxides such as butyl hydroperoxide, t-hexyl hydroperoxide, di-t-butyl hydroperoxide, hydrogen peroxide, azo compounds such as azobisisobutyronitrile, and peroxides such as ammonium persulfate and potassium persulfate. Redox initiators comprising a sulfuric acid compound, a perchloric acid compound, a perboric acid compound, and a combination of a peroxide and a reducing sulfoxy compound.

The polymerization temperature varies depending on the type and amount of the polymerization initiator used, but is usually from 40 to 120 ° C., preferably from 60 to 95 ° C. The polymerization initiator is, for example, an aqueous phase,
It may be added to one or both of the monomer phases.

As the emulsifier, anionic, cationic and nonionic surfactants can be used. In particular, an anionic surfactant is preferable. Specific examples of anionic surfactants include carboxylate salts such as potassium oleate, sodium stearate, sodium myristate, sodium N-lauroyl sarcosinate and dipotassium alkenyl succinate; sulfate salts such as sodium lauryl sulfate; Sulfonates such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium alkyldiphenyletherdisulfonate;
Phosphate ester salts such as sodium polyoxyethylene alkylphenyl ether phosphate are exemplified.

From the polymer latex obtained by the emulsion polymerization method, a dried polymer powder can be taken out by a coagulation method, a spray drying method or the like. As the coagulation method, a conventionally known method such as an acid coagulation method and a salt coagulation method is used, and a salt coagulation method using calcium acetate, magnesium sulfate, aluminum sulfate or the like is particularly preferable.

Further, it is preferable to use a highly hydrophobic calcium compound such as calcium acetate for the purpose of reducing the water content of the coagulated powder (wet polymer) obtained by coagulating the polymer latex. The concentration of the calcium acetate aqueous solution is preferably 0.1 to 20% by weight, more preferably 1 to 10%. When the concentration is 0.1% by weight or more, the polymer tends to be stably recovered, and when the concentration is 20% by weight or less, the calcium acetate aqueous solution tends to be hardly saturated and precipitated.

It is preferable that the coagulated powder obtained by coagulating the latex is sufficiently washed with pure water at least 5 times per polymer to reduce the amount of coagulant remaining in the polymer. By sufficiently performing the washing, the content of the alkaline earth metal (Ca, Mg, etc.) in the resin composition can be easily reduced to 350 ppm or less. In this case, it is possible to prevent the deterioration of the transparency and the appearance when used.

Next, the washed slurry-like solidified powder is
After being dehydrated by a centrifugal dehydrator, the wet polymer is dried by hot air drying or press extrusion.

The average particle size of the acrylic multi-layer copolymer (A) is determined from the viewpoint of reducing the temperature dependence of haze.
0.05 to 0.09 μm. If it is less than 0.05 μm, the haze at a high temperature becomes large due to the effect of an increase in impurities due to excessive use of an emulsifier during polymerization. Also, 0.0
If it exceeds 9 μm, the scattered light increases at high temperature and the haze increases.

The graft ratio of the acrylic multilayer copolymer (A) is set to 10 to 29% from the viewpoint of maintaining fluidity.
If it is less than 10%, the compatibility with the methacrylic resin is affected and the solvent resistance is reduced. Also, if it exceeds 29%,
The fluidity of the resin composition itself is reduced, and the processability is impaired.

The methacrylic resin (B) contained in the resin composition of the present invention is a resin containing methyl methacrylate as a main component. Specifically, the ratio of methyl methacrylate units (used monomer ratio) is preferably 50% by weight or more. With such a ratio, transparency and weather resistance are improved.

As the methacrylic resin (B), various kinds of conventionally known general hard methacrylic resins and high molecular weight hard methacrylic resins can be used. Reduced viscosity (η) of methacrylic resin (B) in chloroform at 25 ° C. (η
sp / C) is preferably about 30 to 80 ml / g.

The resin composition of the present invention contains the above-mentioned acrylic multi-layer copolymer (A) or methacrylic resin (B) as a main component. Although the composition ratio in the resin composition is not particularly limited, the acrylic multilayer structure polymer (A) is preferably 5 to 100% by weight, and the methacrylic resin (B) is preferably 0 to 95% by weight. It is more preferred that (A) is 10 to 80% by weight and methacrylic resin (B) is 20 to 90% by weight. This resin composition has a small temperature dependence of haze and color tone while maintaining the good appearance of the methacrylic resin, and the molten resin has high fluidity and excellent moldability.

Further, in the resin composition of the present invention,
The content of the alkaline earth metal is 350 ppm or less.
As a result, deterioration of appearance due to an increase in haze at room temperature, and deterioration of transparency and appearance when used at high temperatures are less likely to occur.

The method of mixing the acrylic multi-layer copolymer (A) and the methacrylic resin (B) is not particularly limited, but the method of melt mixing is most preferable.

For example, prior to melt mixing, if necessary, an antioxidant such as a hindered phenol, phosphite, or thioether; a hindered amine, a benzotriazole, a benzophenone, a benzoate, an organic nickel, etc. A light stabilizer; or a V-blender, optionally adding a lubricant, a plasticizer, a dye / pigment, a filler, and the like.
The resin is mixed with a Henschel mixer or the like, and then mixed with a mixing roll, a screw-type extruder, and the like.
The resin composition of the present invention can be obtained by melt-kneading at 300 ° C.

The resin composition of the present invention can be molded by an extrusion molding machine, an injection molding machine or the like. Molded articles obtained from the resin composition of the present invention are excellent in impact resistance, transparency, impact whitening resistance, anti-banding properties, solvent crack resistance, etc., and the temperature dependence of haze and color tone is small, In particular, it is very useful for lamp lenses. Further, the present invention can be applied not only to lamp lenses but also to various fields such as sun visors for vehicles, interior products, and signboards for outdoor use.

[0043]

The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the invention thereto. In the examples, "parts" indicates parts by weight and "%" indicates% by weight. The abbreviations used in the examples are as follows.

MMA: methyl methacrylate MA: methyl acrylate BA: n-butyl acrylate AMA: allyl methacrylate DAM: diallyl maleate St: styrene EDMA: ethylene glycol dimethacrylate BDMA: 1,3-butylene glycol dimethacrylate n-OM: n -Octyl mercaptan t-DM: t-dodecyl mercaptan KPS: potassium persulfate CHP: cumene hydroperoxide t-HH: t-hexyl hydroperoxide t-BH: t-butyl hydroperoxide DBP: di-t-butylper Oxide EDTA · 2Na: disodium ethylenediaminetetraacetate dihydrate SFS: sodium formaldehyde sulfoxylate Emulsifier (1): mono (polyoxyethylene Emissions nonylphenyl ether) 40% phosphoric acid and di (polyoxyethylene nonylphenyl ether) sodium hydroxide phosphate 60% mixture partially neutralized product [Toho Chemical Co., Ltd., trade name Phosphanol LO529].

The measurements of the characteristics shown in the examples were carried out according to the following methods.

[Average particle diameter] Light scattering photometer DLS700
Using Otsuka Electronics Co., Ltd., a sample in a latex state was measured by a dynamic light scattering method.

[Measurement of Graft Ratio] About 1 g of the acrylic multi-layer copolymer powder obtained by coagulation and drying was precisely weighed in a titanium cell, and placed in 30 ml of acetone.
After refluxing for 5 hours, using a super high speed centrifuge 70P-72 for separation manufactured by Hitachi Koki Co., Ltd., 5 ° C., 50,000 rpm
For 60 minutes. Then, about 20 ml of the clear supernatant liquid was removed, and about 20 ml of acetone was added for 3 hours.
Shaking was performed for 0 minutes. In addition, 5 ° C, 50,000 rpm
For 60 minutes. Then, about 30 ml of the clear supernatant was separated and left to dry overnight at room temperature.
It was further dried overnight in a vacuum dryer at 0 ° C. Then
The acetone-insoluble matter remaining in the titanium cell was precisely weighed, and the graft ratio was determined by the following equation.

[0048]

(Equation 1) W ₀ : weight of sample (g) W ₁ : weight of acetone-insoluble part (g) R: weight ratio of (innermost layer + intermediate layer) to the entire acrylic multilayer structure copolymer.

[Measurement of Residual Metal Amount] 2 g of a dry powder of the entire acrylic multi-layer structure copolymer was placed in a platinum dish and completely incinerated with an electric heater.
The solution was taken in a ml volumetric flask, made to a constant volume, and used as a test solution. This was quantified by the atomic absorption method. In Examples, since calcium acetate and magnesium sulfate were used as coagulants, the amount of residual Ca or the amount of residual Mg was measured. The amount of residual metal in the entire resin composition is determined by the amount of residual metal (pp
m) = [X / (X + Y)] × Z [X: compounding amount (% by weight) of acrylic multilayer structure copolymer, Y: compounding amount (% by weight) of methacrylic resin, Z: acrylic compound weight of multilayer structure Alkaline earth metal contained in coalescence].

[Measurement of Haze, Measurement of YI (Yellow Index)] Using a PS60E9ASE injection molding machine manufactured by Nissei Plastics Co., Ltd. at a cylinder temperature of 260 ° C. and 100 × 50 × 2.
mm test piece was prepared and the haze was measured using ASTM-D.
The YI was measured using a Macbeth colorimeter.

[Measurement of Average Particle Diameter] A latex of an acrylic multilayer copolymer was diluted with pure water, and calculated by an absorbance method using a spectrophotometer.

[Measurement of Fluidity (MI)] ASTM D-
It was measured according to 1238.

[Measurement of Solvent Crack Resistance] In a temperature environment of 50 ° C., a wax remover C manufactured by Yushiro Chemical Industry Co., Ltd. was used.
The molded article was immersed in PC, and after 3 hours, the presence or absence of cracks was observed and evaluated according to the following criteria. "O": No crack. "△": Small cracks occurred. “×”: Many cracks.

[Reduced Viscosity] Chloroform 100 at 25 ° C.
The specific viscosity when 1 g of the sample was dissolved in ml was measured and divided by the solute concentration to calculate the reduced viscosity. In this measurement, an automatic viscometer AVL-2C manufactured by Sun Electronics Industry Co., Ltd. was used.

Example 1 300 parts of ion-exchanged water was added to a reaction vessel equipped with a reflux condenser, the temperature was raised to 80 ° C., and 40 parts of a monomer mixture (a-1) having a weight composition ratio shown in Table 1 was added. Fifteen
% (Ie, 6 parts) and the polymerization initiator t-BH 0.006
5 parts and 0.9 part of emulsifier (1) were added, and the mixture was maintained for 30 minutes. Thereafter, iron (II) sulfate heptahydrate was further added to 2.5 × 10 ^−5.
Parts, EDTA · 2Na 7.5 × 10 ^-5 parts, SFS 0.25
Parts were added. Next, the remaining monomer mixture (a-1)
85% of the 40 parts (i.e. 34 parts) and the polymerization initiator t-
0.0371 parts of BH and 2.6 parts of emulsifier (1) are continuously added as a monomer / emulsifier mixture at an increasing rate of 8% / hour of the monomer mixture with respect to water, and then maintained for 1 hour to form the innermost layer. Was polymerized.

Next, SFS was added to the obtained latex.
0.125 parts were added, 60 parts of the monomer mixture (a-2) having a weight composition ratio shown in Table 1 and 0.2 parts of a polymerization initiator CHP were added.
The mixture was continuously added at a rate of 4% / hour at an increasing rate of the monomer mixture with respect to water, and maintained for 2 hours to polymerize the intermediate layer.

Then, SFS 0.1 was added to this latex.
25 parts were added and the mixture was held for 15 minutes. Thereafter, 60 parts of the monomer mixture (a-3) having the composition shown in Table 1 and the initiator t-
0.0319 parts of BH was continuously added at a rate of 10% / hour at an increasing rate of the monomer mixture with respect to water, and the mixture was kept for 1 hour to perform polymerization of the outermost layer. As a result, the average particle size was 0.3.
A latex of an acrylic multi-layer copolymer (A-) having a thickness of 072 μm was obtained.

After coagulating the obtained latex with an aqueous solution of calcium acetate, the polymer was washed with a 20-fold amount of pure water, dehydrated and dried to obtain an acrylic multi-layer polymer (A).
-) Powder was obtained. The residual Ca content of this wet powder is 330p
pm, and the graft ratio of the polymer was 27%.

Next, 25 parts of the obtained powder and MMA97
Part of MA, 3 parts of MA, 55 parts of a general hard methacrylic resin manufactured by Mitsubishi Rayon Co., Ltd. having a reduced viscosity (ηsp / C) of 53 ml / g at 25 ° C. in chloroform, and 95.5 parts of MMA and MA4 Reduced viscosity at 25 ° C in chloroform having a ratio of 0.5 parts (ηsp /
(C) 20 parts of a high-molecular-weight hard methacrylic resin manufactured by Mitsubishi Rayon Co., Ltd. having a concentration of 75 ml / g, 0.2 parts of an antioxidant (A060 manufactured by ADK STAB), 0.15 of an antioxidant (2112). And 0.05 part of an ultraviolet absorber (trade name: Tinuvin P) were mixed with a Henschel mixer.
Then, using a single screw extruder having a diameter of 40 mm, the mixture is melt-kneaded at a cylinder temperature of 230 to 270 ° C. and a die temperature of 260 ° C. to perform pellet shaping, and the obtained pellet-shaped methacrylic resin composition is subjected to injection molding. It was formed into a 2 mm plate. The haze and YI were measured for the injection molded plate.
Further, the fluidity (MI) of the resin composition was measured, and the amount of residual Ca in the resin composition was calculated.

Similarly, a lamp lens is formed,
A lamp body was molded by injection molding using an ABS resin manufactured by Mitsubishi Rayon Co., Ltd., Diapet (registered trademark) ABS3001M. Next, each lamp lens and the lamp body were joined at room temperature by hot plate welding at a welding temperature of 300 ° C. to obtain an integrated lens, and the solvent crack resistance was measured. Table 2 shows the results.

Example 2 300 parts of ion-exchanged water was added to a reaction vessel equipped with a reflux condenser, the temperature was raised to 80 ° C., and 6 × 10 ⁻⁵ parts of iron (II) sulfate heptahydrate, EDTA · 2Na1. 5
After adding × 10 ⁻⁴ parts and 0.3 parts of SFS, 40 parts of the monomer mixture (a-1) having a weight composition ratio shown in Table 1, 0.1 part of a polymerization initiator t-HH and 5.1 parts of an emulsifier (1) were added. 0 parts of mixture 1
/ 10 was added, and the mixture was held for 15 minutes. Then, the remaining mixture was continuously added at a rate of 8% / hour as an increase rate of the monomer mixture to water, and the mixture was held for 1 hour to polymerize the innermost layer.

Next, SFS0.
3 parts, and the monomer mixture (a
-2) A mixture of 60 parts, 0.2 part of a polymerization initiator t-HH and 1 part of an emulsifier (1) is continuously added at a rate of increase of a monomer mixture to water of 4% / hour and kept for 2 hours. do it,
The intermediate layer was polymerized.

Then, 0.2 part of SFS was added to this latex, and the mixture was held for 15 minutes. Then, 60 parts of the monomer mixture (a-3) having the weight composition shown in Table 1 and 0.1 part of the initiator t-HH were added. Polymerization of the outermost layer was performed by continuously adding the monomer mixture at a rate of 10% / hour with respect to water and maintaining the mixture for 1 hour. As a result, a latex of an acrylic multilayer polymer (A-) having an average particle diameter of 0.080 μm was obtained.

The obtained latex was coagulated with an aqueous solution of calcium acetate, then washed, dehydrated and dried with a 20-fold amount of pure water with respect to the polymer to obtain an acrylic multi-layer polymer (A).
-) Powder was obtained. The residual Ca content of this wet powder is 330p
pm, and the graft ratio of the polymer was 27%. Hereinafter, in the same manner as in Example 1, the multilayer acrylic polymer (A
A molded plate using-) was prepared, and physical properties were measured.
Table 2 shows the results.

<Example 3> A molded plate was prepared in the same manner as in Example 1 except that only 100 parts by weight of the acrylic multilayer copolymer (A-) was used and no methacrylic resin was used. Physical properties were measured. Table 2 shows the results.

Example 4 An acrylic multi-layer copolymer (A-) latex was coagulated with an aqueous calcium acetate solution, washed twice with pure water, dehydrated, and dried to obtain an acrylic multi-layer copolymer. A powder of the structural polymer (A-) was obtained. The residual Ca amount of this wet powder was 2000 ppm.
Except that 5 parts of the obtained powder and 70 parts of a general hard methacrylic resin manufactured by Mitsubishi Rayon Co., Ltd., and 25 parts of a high molecular weight hard methacrylic resin also manufactured by Mitsubishi Rayon Co., Ltd. were mixed with a Henschel mixer. A molded plate was prepared in the same manner as in Example 1, and the physical properties were measured. Table 2 shows the results.

<Comparative Example 1> A latex of an acrylic multi-layer copolymer (A-) was coagulated with an aqueous solution of calcium acetate, and the polymer was washed twice with pure water (residual calcium amount: 2000 ppm). A molded plate was prepared in the same manner as in Example 1 except that the amount of the multilayer structure copolymer (A-) was changed to 25 parts by weight, and physical properties were measured. Table 2 shows the results.

Comparative Example 2 First, an acrylic two-layer copolymer (G1) was prepared as follows.

In a reaction vessel equipped with a reflux condenser, 300 parts of ion-exchanged water, 0.05 parts of sodium carbonate, and 0.1 part of emulsifier (1) were added.
48 parts were added, the temperature was raised to 70 ° C., and 0.45 parts of SFS, 0.4 ppm of ferrous sulfate, ED were added to 5 parts of ion-exchanged water.
A mixture to which 1.2 ppm of TA · 2Na was added was added all at once. Next, BA 84.0 parts, St 16.0 parts, AMA 0.0
A mixture consisting of 9 parts, 0.3 part of t-butyl peroxide and 1.0 part of emulsifier (1) was added dropwise over 185 minutes.
Thereafter, the temperature was held for 120 minutes to polymerize the soft innermost layer.

Subsequently, SFS was performed on 5 parts of ion-exchanged water.
The mixture to which 0.12 parts was added was added all at once, and after 15 minutes, M
A mixture of 58 parts of MA, 2 parts of MA, 0.25 parts of n-OM, 0.09 parts of t-butyl peroxide, and 0.4 parts of emulsifier (1) was added dropwise over 90 minutes, and the mixture was held for 60 minutes and held for 60 minutes. Was completed. As a result, a latex of an acrylic two-layer copolymer (G1) having an average particle diameter of 0.12 μm was obtained.

The obtained latex is coagulated with an aqueous solution of magnesium sulfate, and washed with a 20-fold amount of pure water with respect to the polymer.
After dehydration and drying, an acrylic two-layer polymer (G1)
Was obtained.

The residual Mg content of this wet powder was 400 ppm, and the graft ratio of the polymer was 20%. The subsequent operation was evaluated in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 3 The mixture used for the hard outermost layer of the acrylic two-layer copolymer (G1) was prepared using MMA58
Polymerization was carried out in the same manner as in Comparative Example 3 except that the composition was changed to a composition consisting of 2 parts, MA 2 parts, n-OM 0.05 part, t-butyl peroxide 0.09 part, and emulsifier (1) 0.4 part. An acrylic two-layer copolymer (G2) having an average particle size of 0.110 μm was obtained. At this time, the remaining Ca amount is 350 p.
pm, and the graft ratio of the polymer was 39%. The others were evaluated in the same manner as in Comparative Example 3. Table 2 shows the results
Shown in

[0074]

[Table 1]

[0075]

[Table 2] As is evident from the results shown in Table 2, the resin compositions of Examples 1 to 4 have excellent transparency at ordinary temperature and high temperature, and also have excellent solvent resistance, excellent fluidity of the molten resin, and excellent balance of each property. It was. On the other hand, in the resin compositions of Comparative Examples 1 to 3, such good characteristics were not obtained.

[0076]

As described above, according to the present invention,
While maintaining the transparency inherent in methacrylic resin, the temperature dependence of haze and color appearance is small, it can be used in a wide environment, and it has excellent solvent crack resistance and good fluidity. It is possible to provide a resin composition having excellent processability and having various processability.

Since the resin composition of the present invention has an excellent balance of the above-mentioned properties, it is very useful especially as a material constituting a lamp lens. In other applications, it is expected to be a material that can respond to various new molding technologies.

Claims (2)

[Claims] 1. An alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms, 40 to 100% by weight, an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, 0 to 60% by weight, and other copolymerizable monomers. Obtained by polymerizing 100 parts by weight of a monomer or monomer mixture composed of 0 to 20% by weight of a monomer, 0.1 to 5 parts by weight of a crosslinking agent, and 0.1 to 5 parts by weight of a graft crosslinking agent. An innermost layer polymer (a1), in the presence of the innermost layer polymer (a1), 70 to 90% by weight of an alkyl acrylate having 1 to 8 carbon atoms in an alkyl group, 10 to 30% by weight of an aromatic vinyl monomer, And 100 parts by weight of a monomer mixture composed of 0 to 20% by weight of another copolymerizable monomer, 0.1 to 5 parts by weight of a crosslinking agent, and 0.1 to 5 parts by weight of a graft crosslinking agent. Intermediate layer polymer (a2) obtained by polymerization, and In the presence of the layer polymer (a1) and the intermediate layer polymer (a2), 50 to 100% by weight of an alkyl methacrylate having an alkyl group of 1 to 4 and 1 to 4% by weight of an alkyl group having 1 to 4 carbon atoms.
0 to 50% by weight of an alkyl acrylate of
The outermost layer polymer (a3) obtained by polymerizing a monomer or monomer mixture comprising 0 to 20% by weight of other copolymerizable monomers, having an average particle diameter of 0.05 to 0.5. 09μ
m, a resin composition comprising an acrylic multilayer copolymer (A) having a graft ratio of 10 to 29% and having an alkaline earth metal content of 350 ppm or less. 2. A resin composition comprising the resin composition according to claim 1 and a methacrylic resin (B) containing methyl methacrylate as a main component, wherein the content of the alkaline earth metal is 350 ppm or less.