JPH11217412A - Acrylic multilayer structure copolymer, methacylic resin composition therewith and lump lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep haze and temperature-dependency of color tone appearances low and to improve flowability by polymerizing an alkyl methacrylate in the presence of a certain innermost polymer and an intermediate layer polymer. SOLUTION: 100 pts.wt.% monomer mixture comprising (a) 40-100 wt.% of a 1-4C alkyl, methacrylate, (b) 0-60 wt.% of a 1-8C alkyl acrylate and (c) 0-20 wt.% of another copolymerizable monomer; (d) 0.1-5 pts.wt. crossliker; and (e) 0.1-5 pts.wt. graft-crossing agent are pclymerized to obtain an innermost polymer (A). 100 pts.wt. monomer mixture comprising 70-90 wt.% of the component (b), 10-30 wt.% of an aromatic vinyl monomer and 0-20 wt.% of the component (c); 0.1-5 pts.wt. of the component (d); and 0.1-5 pts.wt. of the component (e) are polymerized in the presence of the component (A) to obtain an intermediate layer polymer (B). 50-100 wt.% of the component (a), 0-50 wt.% of the component (b) and 0-20 wt.% of the component (c) are polymerized in the presence of the components (A) and (B) to form an outermost polymer (C), thereby obtaining an acrylic multilayer structure copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic multilayer copolymer, a methacrylic resin composition using the same, and a lamp lens.

[0002]

2. Description of the Related Art As an elastomer component for improving the impact resistance of a methacrylic resin generally used in outdoor applications, diene rubbers and acrylic rubbers can be mentioned. Rubber is used. For this reason, many proposals have been made for acrylic rubber.

For example, Japanese Patent Publication No. 58-1694 proposes the use of an acrylic multi-layer graft rubber having a hard-soft-hard three-layer basic structure and an intermediate layer between each layer. Japanese Patent Publication No. Sho 62-41241 proposes the use of an acrylic multi-layer graft rubber having a four-layer structure of soft-hard-soft-hard. Further, Japanese Patent Application Laid-Open No. 57-85843,
JP-A-320457 and JP-A-7-286084 disclose an acrylic acrylic resin having a hard-soft-hard three-layer structure in which the particle size and composition, the particle size and composition, the graft ratio, the rubber layer thickness and the graft ratio are specified. The use of multilayered graft rubbers has been proposed.

[0004] However, the acrylic graft rubber having a multilayer structure proposed above aims at improving impact resistance while maintaining characteristics such as appearance and weather resistance of methacrylic resin. The methacrylic resin composition obtained by blending in the above-described manner, when the environmental temperature changes, the appearance of haze, yellowish color, etc., changes depending on the temperature due to the difference in the refractive index between the methacrylic resin and the acrylic multi-layer graft rubber. There is a disadvantage that the appearance has a large temperature dependency.

[0005] Further, 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. Melting properties such as fluidity have become required, and when an acrylic multi-layered graft rubber is blended with hard methacrylic resin, the fluidity of the molten resin decreases, the molding temperature range narrows, and the processability increases. There was a problem of getting worse. Further, when the fluidity is reduced, there is a problem that molding distortion tends to remain at the time of molding and the solvent crack resistance due to the molding distortion is deteriorated.

An integrated lamp conventionally used as a vehicular lamp has a lamp lens made of a methacrylic resin and a lamp housing made of an ABS resin or an ASA resin, each of which is formed by a method such as hot plate welding. It was manufactured by welding a lens and a lamp housing. However, conventional integrated lamps suffer from the problem that solvent cracks tend to occur around the welding point of the lamp lens due to paint, wax, and organic solvents contained in wax removers, etc. due to molding distortion due to heat during welding. there were.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a methacrylic resin composition containing an acrylic rubber or the like, which has a small temperature dependency of haze and color tone, can be used in a wide environment, and is excellent. An object of the present invention is to provide a methacrylic resin composition having excellent fluidity and excellent workability capable of coping with various molding techniques. A further object of the present invention is to provide a methacrylic resin composition and a lamp lens having excellent solvent crack resistance.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have found that an acrylic multilayer having a specific composition and structure as an acrylic rubber to be mixed with an acrylic resin. It has been found that the above object can be achieved by using a structural copolymer, and the present invention has been 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 0-2
A polymer mixture obtained by polymerizing 100 parts by weight of a monomer or monomer mixture consisting of 0% by weight, 0.1 to 5 parts by weight of a crosslinking agent and 0.1 to 5 parts by weight of a graft crosslinking agent. In the presence of the innermost layer polymer (a), 70 to 90% by weight of an alkyl acrylate having 1 to 8 carbon atoms in the presence of the innermost layer polymer (a),
30% by weight and other copolymerizable monomers 0 to 20
Intermediate layer polymer obtained by polymerizing 100 parts by weight of a monomer mixture consisting of 100% by weight of a monomer mixture comprising 0.1 to 5 parts by weight of a crosslinking agent and 0.1 to 5 parts by weight of a crosslinking agent. (B) and, in the presence of the innermost layer polymer (a) and the intermediate layer polymer (b), 50 to 100% by weight of an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms,
Alkyl acrylate having 1 to 8 carbon atoms in the alkyl group 0
To 50% by weight and other copolymerizable monomers 0 to 2
An acrylic multi-layer copolymer comprising the outermost polymer (c) obtained by polymerizing 0% by weight of a monomer or a monomer mixture.

Further, the present invention is a methacrylic resin composition comprising 5 to 50% by weight of the above-mentioned acrylic multilayer copolymer and 50 to 95% by weight of a hard methacrylic resin containing methyl methacrylate as a main component.

Further, the present invention relates to an acrylic multi-layer structure copolymer having a reduced viscosity of 0.070 to 0.040% by weight.
5 to 35% by weight of 0.085 (l / g) hard methacrylic resin and a reduced viscosity of 0.050 to 0.065 (l / g)
g) The methacrylic resin composition comprising 35 to 75% by weight of the hard methacrylic resin.

Further, the present invention resides in a lamp lens comprising these methacrylic resin compositions.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The acrylic multilayer copolymer of the present invention has a three-layer copolymer comprising an innermost layer polymer (a), an intermediate layer polymer (b) and an outermost layer polymer (c). Combine.

The innermost layer polymer (a) is an alkyl acrylate having an alkyl group having 1 to 4 carbon atoms, 40 to 100% by weight, preferably 80 to 100% by weight, and an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms. 100 parts by weight of a monomer or monomer mixture comprising 0 to 60% by weight, preferably 0 to 20% by weight and 0 to 20% by weight of other copolymerizable monomers, and 0.1 to 5% of a crosslinking agent. It is a polymer of a monomer mixture consisting of parts by weight and 0.1 to 5 parts by weight of a graft crosslinking agent. Outside of these ranges, the transparency and the temperature dependence of the color appearance will be poor.

The alkyl group used here has 1 carbon atom.
Examples of the alkyl methacrylates of (4) to (4) include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and n-butyl methacrylate. Examples of the alkyl acrylate having 1 to 8 carbon atoms in the alkyl group include methyl acrylate, ethyl acrylate, i-propyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate.

Other copolymerizable monomers include aromatic vinyl monomers such as styrene, α-methylstyrene and vinyltoluene, phenyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, phenyl acrylate, cyclohexyl acrylate, and benzyl acrylate. And the like. Among these, it is preferable to use an aromatic vinyl monomer.
More preferably, it is about 7% by weight.

As the crosslinking agent, ethylene glycol,
Examples include 1,3-butylene glycol, triethylene glycol, diesters of acrylic acid or methacrylic acid of polyethylene glycol, trimethylolpropane triacrylate, triallyl isocyanurate, and pentaerythritol tetraacrylate. Also,
Acrylic acid, methacrylic acid,
Allyl, methallyl, crotyl esters of maleic acid, fumaric acid and itaconic acid and the like can be mentioned. The cross-linking agent has substantially the same reactivity of a plurality of functional groups of the cross-linking agent, and mainly forms cross-linking in the layer.
At least one of the plurality of functional groups has a different reactivity from the others, and has a function of effectively forming a chemical bond between layers due to the difference in the reactivity. Innermost layer polymer (a)
The amount of the crosslinking agent and the grafting agent used in the above is within the above range, but the ratio of the crosslinking agent / grafting agent is as follows:
The weight ratio is preferably in the range of 1/10 to 20/1, and more preferably in the range of 1/1 to 10/1.

The intermediate layer polymer (b) comprises 70 to 90% by weight of an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group;
Preferably 80 to 85% by weight, aromatic vinyl monomer 10
100 parts by weight of a monomer mixture consisting of 0 to 30% by weight, preferably 15 to 20% by weight and 0 to 20% by weight of other copolymerizable monomers, and 0.1 to 5 parts by weight of a crosslinking agent, preferably A weight obtained by polymerizing a monomer mixture consisting of 1 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 in the presence of the innermost layer polymer (a). It is united. As the above-mentioned monomer used for the intermediate layer polymer (b), the same monomers as those described for the innermost layer polymer (a) can be used. The amounts of the crosslinking agent and the grafting agent used in the intermediate layer polymer (b) are in the above ranges, but the ratio of the crosslinking agent / grafting agent is 1/3 by weight.
It is preferably in the range of 0 to 10/1, more preferably in the range of 1/20 to 2/1.

The outermost layer polymer (c) contains 50 to 100% by weight, preferably 80 to 99% by weight, more preferably 90 to 100% by weight of an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms.
0 to 97% by weight, 0 to 50% by weight, preferably 1 to 20% by weight, more preferably 3 to 10% by weight, and other copolymerizable monomers 0 The innermost layer polymer (a) and the intermediate layer polymer (b)
Is a polymer obtained by polymerization in the presence of As the above-mentioned monomer used for the outermost layer polymer (c), the same monomers as those described for the innermost layer polymer (a) and the intermediate layer polymer (b) can be used.

In polymerizing the outermost layer polymer (c), it is desirable to control the graft ratio using a chain transfer agent. Adjusting the graft ratio with the chain transfer agent has the effect of improving the compatibility with the matrix resin and further improving the fluidity of the methacrylic resin composition of the present invention. As the chain transfer agent used to adjust the graft ratio, use of an alkyl mercaptan is desirable, and examples thereof include n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, and t-dodecyl mercaptan.

The amount of the chain transfer agent used is 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 (c).

The amount of the monomer used in each layer constituting the acrylic multi-layer copolymer of the present invention is not particularly limited, but the innermost layer polymer (a) is 5 to 50 parts by weight,
The intermediate layer polymer (b) is 50 to 95 parts by weight, and the outermost layer polymer (c) is 40 to 100 parts by weight based on 100 parts by weight of the total amount of the innermost layer polymer (a) and the intermediate layer polymer (b). Preferably, the amount is 100 parts by weight.

The average particle size and the graft ratio of the acrylic multi-layer copolymer of the present invention are not particularly limited, but in terms of maintaining good transparency (haze), color tone, and fluidity, the average particle size is 0.1. Those having a range of from 0.05 to 0.09 μm are preferred, and those having a range of from 0.05 to 0.07 μm are more preferred. Further, the graft ratio is preferably in the range of 10 to 29%, and more preferably 20 to 29%.
More preferably, it is in the range of 28%.

The acrylic multi-layer copolymer of the present invention described above is produced by a known emulsion polymerization method. An example of the 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 constituting the innermost layer polymer (a) is added and polymerized. In the presence of the innermost layer polymer (a), a monomer mixture constituting the intermediate layer polymer (b) is added and polymerized to form a shell around the innermost layer polymer (a). Subsequently, in the presence of the particles, a monomer mixture constituting the outermost layer polymer (c) is added and polymerized to obtain a desired acrylic multilayer copolymer.

The polymerization initiator used is not particularly limited. Examples of the radical polymerization initiator include benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, t-hexyl hydroperoxide, di-t- Butyl peroxide, peroxides such as hydrogen peroxide, azo compounds such as azobisisobutyronitrile, ammonium persulfate, persulfate compounds such as potassium persulfate, perchlorate compounds, perborate compounds, and peroxides. Redox initiators comprising a combination with a reducing sulfoxy compound are exemplified.

The polymerization temperature varies depending on the type and amount of the polymerization initiator used, but is preferably from 40 to 120 ° C, more preferably from 60 to 95 ° C.

The polymerization initiator may be added to one or both of the aqueous phase and the monomer phase.

As the emulsifier, an anionic, cationic or nonionic surfactant can be used, and an anionic surfactant is particularly preferable. Examples of the anionic surfactant include potassium oleate, sodium stearate, sodium myristate, sodium N-lauroyl sarcosinate, dipotassium alkenylsuccinate and the like, carboxylate salts such as sodium lauryl sulfate, and dioctyl sulfosuccinic acid. Sulfonates such as sodium, sodium dodecylbenzenesulfonate and sodium alkyldiphenylether disulfonate; and phosphoric acid ester salts such as sodium polyoxyethylene alkylphenylether phosphate and the like.

The polymer latex obtained by the emulsion polymerization method can use a known coagulation method such as an acid coagulation method, a salt coagulation method, a freeze coagulation method, and a spray drying method. As the acid coagulation method, inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, and organic acids such as acetic acid can be used. As the salt coagulation method, inorganic salts such as sodium sulfate, magnesium sulfate, aluminum sulfate, and calcium chloride can be used. And organic salts such as calcium acetate and magnesium acetate. The coagulated polymer is further washed, dehydrated and dried.

The methacrylic resin composition of the present invention comprises the above-mentioned acrylic multi-layer copolymer and a hard methacrylic resin containing methyl methacrylate units as main components. That is, it is a methacrylic resin composition comprising 5 to 50% by weight of an acrylic multilayer copolymer and 50 to 95% by weight of a hard methacrylic resin containing methyl methacrylate as a main component. Such methacrylic resin composition,
While maintaining the good appearance of methacrylic resin, haze,
The temperature dependence of the color tone is small, and the molten resin has high fluidity and excellent moldability.

The ratio of methyl methacrylate units in the hard methacrylic resin is preferably at least 50% by weight. If it is less than 50% by weight, transparency or weather resistance will be poor. Another monomer unit in the hard methacrylic resin includes a vinyl monomer copolymerizable with methyl methacrylate. Among them, methyl acrylate,
Ethyl acrylate, i-propyl acrylate, n-
Alkyl acrylates having 1 to 8 carbon atoms such as butyl acrylate and 2-ethylhexyl acrylate are preferred. Further, in order to impart heat resistance to the hard methacrylic resin, maleic anhydride, N-substituted maleimide, or the like, α-methylstyrene, or the like can be copolymerized. On the other hand, if the ratio of the acrylic multi-layer copolymer to the hard methacrylic resin is out of the above range, the haze, the temperature dependency of the color tone, and the fluidity of the molten resin become poor.

A molded article obtained from the methacrylic resin composition has a small molding distortion and therefore has excellent solvent crack resistance. The reduced viscosity is 0.070 to 0.085 (l
/ G) of hard methacrylic resin of 5 to 35% by weight, reduced viscosity of 0.050 to 0.065 (l / g) of 35 to 75% by weight of hard methacrylic resin, and the above-mentioned acrylic multilayer copolymer 10 to 40 The methacrylic resin composition composed of% by weight has more excellent solvent crack resistance and is particularly suitable for a lamp lens.

The reduced viscosity is 0.070 to 0.085 (l /
g) 10 to 30% by weight of a hard methacrylic resin, 40 to 70% by weight of a hard methacrylic resin having a reduced viscosity of 0.050 to 0.065 (l / g), and 15 to 35% by weight of the above-mentioned acrylic multilayer copolymer. % Of the methacrylic resin composition becomes more excellent in solvent crack resistance.
The reduced viscosity in the present invention is a value obtained by dividing a specific viscosity when 1 g of a resin is dissolved in 100 ml of chloroform at 25 ° C. by a solute concentration, and can be measured by a known method.

The hard methacrylic resin can be obtained by a known polymerization method such as emulsion polymerization, suspension polymerization, bulk polymerization, and solution polymerization. Hard methacrylic resins having different reduced viscosities can be obtained by known methods such as changing the polymerization conditions and the type and amount of the chain transfer agent.

The mixing method for forming the composition of the acrylic multi-layer copolymer and the hard methacrylic resin is not particularly limited, but a method of melt mixing is ideal. Prior to melt mixing, if necessary, hindered phenol-based, phosphite-based, thioether-based antioxidants, hindered amine-based, benzotriazole-based, benzophenone-based, benzoate-based, organic nickel-based light stabilizers, Alternatively, a lubricant, a plasticizer, a dye / pigment, a filler, etc. are appropriately added, mixed with a resin using a V-type blender, a Henschel mixer, or the like, and then mixed and kneaded at 150 to 300 ° C. using a screw-type extruder. A methacrylic resin composition comprising an acrylic multi-layer copolymer and a hard methacrylic resin can be obtained.

The methacrylic resin composition thus obtained is molded by using an extruder, an injection molding machine or the like.
A molded article having excellent impact resistance, transparency, impact whitening resistance, colorfastness, and solvent crack resistance, and having a small temperature dependence of haze and color appearance can be obtained, and is particularly useful for lamp lenses.

[0038]

The present invention will be further described below with reference to examples and comparative examples. In the description, "parts" indicates parts by weight. The abbreviations of the compounds used in each example 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-butyl peroxide EDTA 2Na: disodium ethylenediaminetetraacetate dihydrate SFS: sodium formaldehyde sulfoxylate Emulsifier (1): mono (polyoxyethylene nonylphenyl ether) Ether) 40% phosphoric acid and di (polyoxyethylene nonylphenyl ether) sodium hydroxide phosphate 60% mixture partially neutralized product

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

[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. at 5 ° C. and 50,000 rpm for 6 hours.
Centrifugation was performed for 0 minutes. The clear supernatant is then
Then, about 20 ml of acetone was added, and the mixture was shaken for 30 minutes, and centrifuged again at 5 ° C. and 50,000 rpm for 60 minutes. Next, 30 ml of the clear supernatant liquid was separated, left to dry at room temperature overnight, and further dried in a vacuum dryer at 50 ° C. overnight. Next, the acetone insoluble solution remaining in the titanium cell was precisely weighed, and the graft ratio was determined by the following equation.

[0041]

(Equation 1)

[Measurement of Haze] PS manufactured by Nissei Resin Co., Ltd.
Using a 60E9ASE injection molding machine, cylinder temperature 26
A test piece of 100 mm × 50 mm × 2 mm was prepared at 0 ° C., and the measurement was performed based on ASTM-D1003.

[YI (Yellow Index)] 100 mm × 50 mm × 2 mm at 260 ° C. cylinder temperature using a PS60E9ASE injection molding machine manufactured by Nissei Plastics Co., Ltd.
Were prepared, and the color tone was measured with a Macbeth color difference meter.

[Measurement of Fluidity (MI)] ASTM D-
1238.

[Measurement of Reduced Viscosity] The value was measured by dissolving 1 g of resin in 100 ml of chloroform at 25 ° C. using an automatic viscometer AVL-2C manufactured by Sun Electronics Co., Ltd.

[Measurement of Solvent Crack Resistance] The molded article was immersed in a wax remover CPC manufactured by Yushiro Chemical Industry Co., Ltd. in a temperature environment of 50 ° C., and after 3 hours, the presence or absence of cracks was observed.

Example 1 300 parts of ion-exchanged water, 0.09 parts of sodium carbonate, and 0.9 parts of boric acid were added to a reaction vessel equipped with a reflux condenser, and the temperature was raised to 80 ° C., as shown in Table 1. 45 parts of monomer mixture (I-1) having composition and emulsifier (1)
1/15 of the mixture of 4.5 parts was added, and the polymerization initiator KPS was added.
After adding 0.05 part and holding for 15 minutes, the remaining mixture of the monomer and the emulsifier is added continuously at a rate of 13% / hour of the increase of the monomer mixture with respect to water, and then held for 1 hour. Then, the innermost layer was polymerized.

Then, in the presence of this latex, 0.1 part of a polymerization initiator KPS was added, and then a mixture of 55 parts of a monomer mixture (II-1) and 0.5 part of an emulsifier (1) shown in Table 1 was added. Was continuously added at a rate of 8% / hour at an increasing rate of the monomer mixture with respect to water, and then maintained for 2.5 hours to polymerize the intermediate layer.

Next, in the presence of this latex, KPS
After adding 0.05 part and holding for 15 minutes, 80 parts of the monomer mixture (III-1) shown in Table 1 were continuously added at a rate of 10% / hour at an increasing rate of the monomer mixture with respect to water. After the addition, the mixture was kept for 1 hour to polymerize the outermost layer, thereby obtaining a latex of an acrylic multilayer copolymer G-1. After coagulating the obtained latex with an aqueous solution of calcium acetate, washing, dehydration, and drying are performed to obtain an acrylic multi-layer copolymer G-.
1 was obtained.

Next, 25 parts of the polymer powder and MMA9
After mixing 7 parts and 75 parts of hard methacrylic resin consisting of 3 parts of MA with a Henschel mixer, the cylinder temperature was 230 to 270 using a single screw extruder having a diameter of 40 mm.
The mixture was melt-kneaded at a die temperature of 260 ° C. and extruded.
A test piece was obtained by injection molding at 60 ° C. Table 2 shows the evaluation results of the test pieces, the average particle diameter of the copolymer, and the graft ratio.
It was shown to.

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
× 10 ^-4 parts, after adding 0.3 parts of SFS, 1/10 of the mixture of 40 parts of the monomer mixture (I-2), 0.1 part of the polymerization initiator t-HH and 5.0 parts of the emulsifier (1). And add 15
After holding the mixture, the remaining mixture of the monomer, the polymerization initiator and the emulsifier is continuously added at a rate of increase of the monomer mixture to water of 8% / hour. Polymerization was performed.

Then, in the presence of this latex, SFS
After adding 0.3 part, the monomer mixture (II
-2) A mixture of 60 parts, polymerization initiator t-HH 0.2 part and emulsifier (1) 1 part was continuously added at a rate of 4% / hour at an increasing rate of the monomer mixture with respect to water. The polymerization was carried out for the intermediate layer while keeping the time.

Next, in the presence of this latex, SFS
After adding 0.2 part and holding for 15 minutes, 60 parts of the monomer mixture (III-2) shown in Table 1 and initiator t-HH 0.1
Parts were continuously added at a rate of 10% / hour at an increasing rate of the monomer mixture with respect to water, and then maintained for 1 hour to polymerize the outermost layer to obtain an acrylic multi-layer copolymer G-2. Latex was obtained. After coagulating the obtained latex with an aqueous solution of calcium acetate, washing, dehydration, and drying were performed to obtain a powder of an acrylic multilayer copolymer G-2. Thereafter, the same operation as in Example 1 was performed, and the results in Table 2 were obtained.

Comparative Example 1 The results in Table 2 were obtained by operating in the same manner as in Example 1 except that the amount of the acrylic multilayer structure copolymer G-1 to be added to the hard methacrylic resin was changed to 3 parts. .

Comparative Example 2 The results in Table 2 were obtained by operating in the same manner as in Example 1 except that the amount of the acrylic multi-layer copolymer G-1 mixed with the hard methacrylic resin was changed to 60 parts. .

Example 3 300 parts of ion-exchanged water was added to a reaction vessel equipped with a reflux condenser, the temperature was raised to 80 ° C., and 15% of 40 parts of the monomer mixture (I-1) shown in Table 1 was added. 0.0065 parts of polymerization initiator t-BH and 0.9 of emulsifier (1)
And after holding for 30 minutes, 2.5 × 10 ⁻⁵ parts of iron (II) sulfate heptahydrate, 7.5 × 10 ⁻⁵ of EDTA · 2Na
^-5 parts and 0.25 part of SFS were added. Next, 85% of the remaining 40 parts of the monomer mixture (I-1) and the polymerization initiator tB
0.0371 parts of H and 2.6 parts of emulsifier (1) were continuously added to the monomer / emulsifier mixture at an increasing rate of 8% / hour of the monomer mixture with respect to water, and then maintained for 1 hour. The innermost layer was polymerized.

Then, in the presence of this latex, SFS
After adding 0.125 part, a mixture of 60 parts of the monomer mixture (II-1) shown in Table 1 and 0.2 part of the polymerization initiator CHP was added at a rate of 4% / hour of increase of the monomer mixture to water. , And the mixture was kept for 2 hours to polymerize the intermediate layer.

Then, in the presence of this latex, SFS
0.125 parts was added and the mixture was held for 15 minutes, and then the monomer mixture (III
-1) and 60 parts of the same monomer mixture as in the polymerization initiator tB
0.0319 parts of H was added continuously at a rate of 10% / hour at an increasing rate of the monomer mixture with respect to water, and then the mixture was held for 1 hour to polymerize the outermost layer and to carry out the acrylic multi-layer copolymer G-. 3 latex was obtained. The obtained latex was coagulated with an aqueous solution of calcium acetate, and then washed, dehydrated, and dried to obtain a powder of an acrylic multilayer copolymer G-3. Thereafter, the same operation as in Example 1 was performed, and the results in Table 2 were obtained.

Example 4 25 parts of the acrylic multi-layer copolymer G-3 obtained in Example 3 and MMA9
Reduced viscosity of 7.5 parts consisting of 7.5 parts and 2.5 parts of MA
7 (l / g) 20 parts of hard methacrylic resin, MMA9
Reduced viscosity consisting of 5.5 parts and 4.5 parts of MA, 0.05
4 (l / g) hard methacrylic resin 55 parts, hindered phenol heat stabilizer AO-60 (Asahi Denka Kogyo Co., Ltd.)
0.2 parts, phosphite heat stabilizer 211
0.15 parts of 2 (manufactured by Asahi Denka Kogyo Co., Ltd.) and tinuvin P (trade name, manufactured by Cibagaigii)
After mixing with 0.05 part with a Henschel mixer, using a single screw extruder having a diameter of 40 mm, the cylinder temperature was changed to 230.
~ 270 ° C, melt kneading at a die temperature of 260 ° C and extrusion,
A pellet-shaped methacrylic resin composition was obtained.

The methacrylic resin composition in the form of a pellet was molded into a lamp lens at a cylinder temperature of 260 ° C. using an IS-220FB injection molding machine manufactured by Toshiba Machine Co., Ltd. Separately, as an ASA resin, Diarack (registered trademark, manufactured by Mitsubishi Rayon Co., Ltd.) TW20 is used as a Toshiba Machine Co., Ltd.
The lamp housing was molded at a cylinder temperature of 240 ° C. using an IS-220FB injection molding machine. The obtained lamp lens and lamp housing were joined at room temperature by hot plate welding at a welding temperature of 300 ° C. to produce an integrated lamp shown in FIG. 1, and the solvent crack resistance was measured. The results are shown in Table 3. The solvent crack resistance was evaluated as follows: ○ when no crack occurred around the portion where the lamp lens made of the methacrylic resin composition was welded to the hot plate, Δ when small cracks slightly occurred, and Δ When it occurred, it was evaluated as x.

Example 5 25 parts of the acrylic multilayer copolymer G-3 obtained in Example 3 and MMA9
Reduced viscosity consisting of 5.5 parts and 4.5 parts of MA, 0.05
Production and evaluation of a test piece and an integrated lamp were performed in the same manner as in Example 3 using 75 parts of 4 (l / g) hard methacrylic resin. Table 3 shows the results.

Comparative Example 3 A reaction vessel equipped with a reflux condenser was charged with 300 parts of ion-exchanged water, 0.05 parts of sodium carbonate and 0.48 part of emulsifier (1), and heated to 70 ° C. A mixture of 0.48 part of SFS, 0.4 ppm of ferrous sulfate, and 1.2 ppm of EDTA · 2Na was added to 5 parts at a time. Next, 84.0 parts of BA, St1
A mixture of 6.0 parts, 0.9 parts of AMA, 0.3 parts of t-BH, and 1.0 part of emulsifier (1) was dropped over 185 minutes, and the mixture was held for 120 minutes to polymerize the soft innermost layer. . Subsequently, SFS 0.12 was added to 5 parts of ion-exchanged water.
Parts of the mixture were added at once, and after 15 minutes, MMA58 was added.
Parts, MA2 parts, n-OM 0.25 parts, t-BH 0.09
Parts and a mixture consisting of 0.4 part of emulsifier (1) were added dropwise over 90 minutes, and then maintained for 60 minutes to complete the polymerization of the hard outermost layer to obtain a two-layer copolymer G-4 latex.
After coagulating the obtained latex with an aqueous solution of calcium acetate, washing, dehydration and drying were performed to obtain a powder of an acrylic multilayer copolymer G-4. Thereafter, the same operation as in Example 4 was performed, and the results in Table 3 were obtained.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

The acrylic multi-layer copolymer obtained by the present invention and the methacrylic resin composition using the same are obtained while maintaining the transparency inherent in the methacrylic resin.
Since the haze and color appearance are less dependent on temperature and the flowability of the molten resin is excellent in processability, it can correspond to various molding techniques. Further, it has a small molding distortion and excellent solvent crack resistance, and is most suitable for a lamp lens.

[Brief description of the drawings]

FIG. 1 is a perspective view of an integrated lamp using a lamp lens of the present invention.

[Explanation of symbols]

 1 Lamp lens made of methacrylic resin composition 2 Lamp housing made of ASA resin

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08F 220: 12) (C08L 33/12 51:00)

Claims (5)

[Claims] 1 to 40% by weight of an alkyl methacrylate having 1 to 4 carbon atoms in an alkyl group, 0 to 60% by weight of an alkyl acrylate having 1 to 8 carbon atoms in an alkyl group, and other copolymerizable monomers. 100 parts by weight of a monomer or monomer mixture consisting of 0 to 20% by weight, and 0.1% of a crosslinking agent.
An innermost layer polymer (a) obtained by polymerizing a monomer mixture comprising 1 to 5 parts by weight and a graft crosslinking agent 0.1 to 5 parts by weight, in the presence of the innermost layer polymer (a), 70 to 90% by weight of an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group,
100 parts by weight of a monomer mixture composed of 10 to 30% by weight of an aromatic vinyl monomer and 0 to 20% by weight of another copolymerizable monomer, 0.1 to 5 parts by weight of a crosslinking agent, and a graft crosslinking agent In the presence of an intermediate layer polymer (b) obtained by polymerizing a monomer mixture consisting of 0.1 to 5 parts by weight, the innermost layer polymer (a) and the intermediate layer polymer (b) 50 to 100% by weight of an alkyl methacrylate having 1 to 4 carbon atoms in the alkyl group, and 1 to 8 carbon atoms in the alkyl group.
Outermost layer polymer (c) obtained by polymerizing a monomer or monomer mixture comprising 0 to 50% by weight of an alkyl acrylate and 0 to 20% by weight of another copolymerizable monomer
Acrylic multi-layer copolymer consisting of 2. The acrylic multi-layer copolymer has an average particle size of 0.05 to 0.09 μm and a graft ratio of 10
The acrylic multi-layer structure copolymer according to claim 1, wherein the content of the acrylic multi-layer copolymer is from 29% to 29%. 3. A methacrylic resin composition comprising 50 to 95% by weight of a hard methacrylic resin containing methyl methacrylate as a main component and 5 to 50% by weight of an acrylic multilayer structure copolymer according to claim 1 or 2. 4. A reduced viscosity of 0.070 to 0.085 (l)
3 to 35% by weight of a hard methacrylic resin having a reduced viscosity of 0.050 to 0.065 (l / g) and 35 to 75% by weight of a hard methacrylic resin having a reduced viscosity of 0.050 to 0.065 (l / g). A methacrylic resin composition comprising 10 to 40% by weight of a multilayer copolymer. 5. A lamp lens comprising the methacrylic resin composition according to claim 3.