JPS6342940B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a methacrylic resin composition that is imparted with impact resistance without impairing the inherent properties of the methacrylic resin. Methacrylic resin has excellent optical properties such as transparency, not only among plastic materials, but even compared to inorganic glass, and has excellent surface gloss, weather resistance, and coloration with dyes and pigments. sex,
It also has excellent moldability, and by taking advantage of these properties, it can be used in lighting, signboards, window materials, optical lenses, tail lenses, meter covers, dust covers, displays, tableware, optical applications, building materials, and electrical equipment parts. , vehicle parts, decoration field,
It is used in many fields such as miscellaneous materials. However, methacrylic resins have a problem of insufficient impact resistance, and the reality is that there is a strong demand for improvement in each application field. Various proposals have been made for a long time as methods for improving the impact resistance of methacrylic resins. The most common and effective method is to disperse a rubber-like elastic body discontinuously in the form of particles at room temperature in a continuous resin phase containing methyl methacrylate as the main component. As the rubbery elastic body, unsaturated rubbery polymers mainly composed of butadiene, butyl acrylate,
Acrylic acid ester polymers containing 2-ethylhexyl acrylate as a main component, or saturated rubber-like elastic bodies such as ethylene/vinyl acetate copolymers are used. Although the introduction of an unsaturated rubber-like elastic material is excellent in terms of impact resistance, there is a problem of poor weather resistance due to the unsaturated bonds in the polymer main chain.On the other hand, the introduction of a saturated rubber-like elastic material Although it has excellent weather resistance, the elastic modulus and elastic recovery of the rubber component itself are low, and it also has poor graft polymerization with hard resin components, so it has poor impact resistance, transparency, surface gloss, etc. There are also problems with the surface appearance, such as poor quality and flow marks. In general, when synthesizing a two-component impact-resistant resin composition in which these rubber-like elastic bodies are uniformly dispersed as particulate discontinuous phases in a continuous phase of hard resin such as methacrylic resin, rubber is an important factor. These factors include the particle size of the elastic material, the degree of crosslinking, the graft polymerizability of the hard resin phase to the rubber phase, and the molecular weight of the hard resin phase. to be influenced. Among these, the degree of crosslinking and graft polymerization of the rubber phase are important.
In other words, the selection of crosslinking or grafting monomers is an important factor. In addition, in recent years, impact-resistant resin compositions or impact-resistant methacrylic resin compositions in which the rubber phase is an acrylic ester-based elastomer with excellent weather resistance, the effect of developing impact resistance of the rubber phase, the transparency of molded products, A method of incorporating a hard resin into rubber particles has been proposed for the purpose of improving stress whitening resistance, pearl-like luster caused by deformation of rubber particles during the molding process, and weather resistance (Japanese Patent Publication No. 52-30996). , Japanese Patent Publication No. 1973
-55233), although its effects are certainly recognized, when viewed as a methacrylic resin, it still has problems in terms of transparency and surface gloss. In view of the above facts, the present inventors have conducted intensive studies on methacrylic resins that have been added with impact resistance without impairing the original excellent properties of methacrylic resins such as transparency, surface gloss, surface appearance, and weather resistance. By blending methacrylic resin whose main component is methyl methacrylate with a multilayer methacrylic resin with a special structure, it is possible to develop impact resistance.
The inventors have discovered that it is possible to obtain a methacrylic resin composition with excellent appearance of molded products, and have thus arrived at the present invention. That is, the gist of the present invention is that 5 to 50 parts by weight of a hard crosslinked resin (A) containing 80% by weight or more of methyl methacrylate units is contained inside the particles, and the alkyl group has 1 to 8 carbon atoms. 69.9 to 89.9% by weight of at least one acrylic acid alkyl ester and styrene alone or a mixture of styrene and its derivatives10
~30% by weight and the following formula or 0.1 to 10% by weight of at least one substance shown in
In the presence of 100 parts by weight of a multi-layered acrylic elastomer with a particle size of 0.2 to 0.45 μm, which constitutes the outer layer, 95 to 50 parts by weight of a crosslinked acrylic ester copolymer (B) of a monomer mixture consisting of , methyl methacrylate
80 to 100% by weight, at least one acrylic acid alkyl ester having an alkyl group of 1 to 8 carbon atoms, 0 to 100% by weight;
Obtained by polymerizing 10 to 1000 parts by weight of a monomer or monomer mixture (C) consisting of 20% by weight and 0 to 10% by weight of other vinyl monomers copolymerizable with this monomer. Multi-structure methacrylic resin [] and
A methacrylic resin [] which is a polymer of 80 to 100% by weight of methyl methacrylate and 0 to 20% by weight of vinyl or vinylidene monomer is blended, and 1 to 70% by weight of a multi-structure acrylic system is added to the composition. Elastic body []
A methacrylic resin composition with excellent impact resistance, which contains The most important feature of the present invention is that when the crosslinked acrylic ester copolymer (B) is provided on the outer layer of the hard crosslinked resin core by polymerization, the formula (1) and
The method uses a multi-structure methacrylic resin obtained by using the special substance shown in (2) as a crosslinking agent. The hard crosslinked resin phase (A) used in the present invention, the non-crosslinked hard resin, and the methacrylic resin used in the blend are auxiliary agents that are individually required at each synthesis stage in order to impart good transparency. It is desirable that the monomer compositions excluding the crosslinkable monomer component be the same or very similar. In addition, the refractive index of the crosslinked acrylic ester copolymer (B) is
It is preferable to make it very similar to the hard resin segment described above. Furthermore, in a resin composition obtained by dispersing rubber particles in a continuous resin phase, it is necessary to consider the diameter of the dispersed rubber particles in order to balance transparency, surface appearance, and impact resistance performance. In the composition of the present invention, in order to obtain a composition excellent in both transparency and impact resistance, when the polymerization of the crosslinked acrylic ester copolymer (B) is substantially completed, the
A range of 0.45 μm is preferred. If the particle size is less than 0.2 μm, the final composition obtained will have good transparency, but the impact resistance will be poor.
If it exceeds 0.45 μm, the final composition will have excellent impact resistance, but its transparency and surface appearance will be poor. The multi-structure acrylic elastic body [] in the present invention has a hard crosslinked resin (A) containing 80% by weight or more of methyl methacrylate units inside the particles,
The outer layer is a cross-linked acrylic ester copolymer (B)
It consists of a structure with The hard crosslinked resin (A) in the present invention is methyl methacrylate alone or 80 to 100% by weight of methyl methacrylate and 0% of other copolymerizable vinyl or vinylidene monomers.
Monomer or monomer mixture consisting of ~20% by weight
100 parts by weight, 0.1 to 10 parts by weight, more preferably
It is a copolymer obtained by polymerization with the addition of 0.5 to 5 parts by weight of a crosslinkable monomer, and is preferably 5 to 50 parts by weight, more preferably 10 parts by weight out of 100 parts by weight of the multilayer acrylic elastomer. It is necessary to contain up to 40 parts by weight. If the amount is less than 5 parts by weight, the effect of developing impact resistance will be small and transparency will also decrease. 50 on the contrary
If the amount exceeds 1 part by weight, the surface gloss tends to decrease and the impact resistance also tends to decrease. Examples of vinyl or vinylidene monomers copolymerizable with methyl methacrylate used in the polymerization of the hard crosslinked resin (A) include styrene, acrylonitrile, and acrylic acid alkyl esters in which the alkyl group has 1 to 8 carbon atoms. . Further, the crosslinkable monomer used in the polymerization of the hard crosslinked resin (A) does not need to be particularly limited as long as it copolymerizes with methyl methacrylate, and commonly used,
Bifunctional monomers such as ethylene glycol dimethacrylate, ethylene glycol diacrylate, 1,3-butylene dimethacrylate, and tetraethylene glycol diacrylate, or trimethylolpropane triacrylate, triallyl cyanurate, triallyl isocyanunate, etc. No. 3
Functional monomers or tetrafunctional monomers such as pentaerythritol tetraacrylate can be used alone or in combination. The crosslinked acrylic ester copolymer (B) preferably contains at least one of n-butyl acrylate and 2-ethylhexyl acrylate among the acrylic alkyl ester group in which the alkyl group has 1 to 8 carbon atoms, 69.9 to 89.9% by weight. % and styrene alone or a mixture of styrene and its derivatives 10-30% by weight and the following formula (Allyl sorbate; hereinafter abbreviated as “ASV”) or (Allyl cinnamate; hereinafter abbreviated as "ACM") 0.1 to 10% by weight of at least one substance represented by
It is a copolymer of a monomer mixture consisting of a range of 95 to 50
Polymerize parts by weight. The composition ratio of the acrylic acid ester monomer and styrene or a mixture of styrene and its derivatives is one of the important factors for imparting transparency, and transparency decreases outside the above composition range. The substances represented by formulas (1) and (2) are one of the most important components of the present invention, and the objects of the present invention are thereby achieved.
Although the details of its effects are not clear,
It is inferred that this is because the degree of crosslinking of the crosslinked acrylic ester copolymer (B) and the graft polymerizability with methyl methacrylate are controlled in a well-balanced manner. The appropriate amount to add is 0.1 to 10% by weight, although the appropriate value differs depending on whether it is used alone or in combination.
A range of is appropriate. In addition to the substances represented by formulas (1) and (2), a known polyfunctional monomer can also be used in a range of 0 to 9% by weight. Further, this polyfunctional monomer does not need to be particularly limited and is one commonly used. Specific compounds include ethylene glycol di(meth)acrylate, 1,3
Butylene di(meth)acrylate, tetraethylene glycol di(meth)acrylate, divinylbenzene, etc. can be used. Next, the monomer or monomer mixture (C) is polymerized in the presence of the multi-structure acrylic elastomer [ ], and the component composition constituting this is 80 to 100% by weight of methyl methacrylate, carbon of the alkyl group, Numbers 1-8
0 to 20% by weight of at least one acrylic acid alkyl ester and 0 to 10% by weight of another vinyl monomer copolymerizable therewith. If the content of methyl methacrylate in the monomer or monomer mixture (C) is less than 80% by weight, properties such as transparency and heat resistance will be poor, and the acrylic acid alkyl ester copolymerized with it will be inferior. Examples include methyl acrylate, ethyl acrylate, butyl acrylate, and the like. Other vinyl monomers that can be used as copolymerization components include styrene, acrylonitrile, and methacrylic acid. If the amount of acrylic ester in the monomer or monomer mixture (C) exceeds 20% by weight, it is unfavorable in terms of heat resistance and transparency of the final composition.
Moreover, if the amount of other copolymerizable vinyl monomers exceeds 10% by weight, it is unfavorable in terms of transparency, heat resistance, water resistance, etc. The monomer or monomer mixture (C) must be polymerized in an amount of 10 to 1000 parts by weight per 100 parts by weight of the multilayer acrylic elastomer. If it is less than 10 parts by weight, it is not preferable because impact resistance may be poor or surface gloss may be reduced. while 1000
If the amount exceeds 1 part by weight, productivity decreases, which is not preferable. A degree of polymerization regulator such as mercaptan may be used in the monomer or monomer mixture (C) to adjust the molecular weight as necessary. Examples of the polymerization degree regulator that can be used include alkyl mercaptans, thioglycolic acid and its esters, β-mercaptopropionic acid and its esters, and aromatic mercaptans such as thiophenol and thiocresol. The multi-structure methacrylic resin obtained by the above series of polymerization processes is methyl methacrylate.
80 to 100% by weight and 0 to 20% by weight of other vinyl or vinylidene monomers, such as methacrylic resin, which is a polymer with an acrylic ester having an alkyl group having 1 to 4 carbon atoms, and multiplexed. The structural acrylic elastic body [ ] is used in a content of 1 to 70% by weight. Since it is particularly preferable to manufacture the multi-structure methacrylic resin of the present invention by emulsion polymerization, an example in which emulsion polymerization is used will be described. After adding deionized water and an emulsifier if necessary to the reaction vessel, the monomer mixture constituting the hard crosslinked resin (A) is polymerized, and then the monomer mixture constituting the crosslinked acrylic ester copolymer (B) is polymerized. The monomer mixture is polymerized, and then the monomer or monomer mixture (C) is polymerized. Polymerization temperature is 30-120℃, more preferably 50-100℃
It is ℃. The polymerization time varies depending on the type and amount of the polymerization initiator and emulsifier, the polymerization temperature, etc., but is usually 0.5 to 7 hours for each polymerization step (A), (B), and (C). The ratio of polymer to water is monomer/water = 1/20 to 1/1
is preferred. A polymerization initiator and an emulsifier can be added to either or both of the aqueous monomer phases. The monomers in the polymerization steps (A), (B), and (C) can be charged all at once or in portions, but the split-charging method is more preferable from the viewpoint of heat generation during polymerization. The emulsifier is not particularly limited as long as it is a commonly used emulsifier, and examples of emulsifiers that can be used include long-chain alkyl carboxylates, sulfosuccinic acid alkyl ester salts, alkylbenzene sulfonates, and the like. There is no need to particularly limit the type of polymerization initiator, and commonly used water-soluble inorganic initiators such as persulfates and perborates can be used alone or in combination with sulfites, thiosulfates, etc. as redox initiators. It can also be used as Also, organic hydroperoxide
Redox initiation systems such as ferrous salts, organic hydroperoxide-sodium sulfoxylate, benzoyl peroxide, azobisisobutyronitrile, and the like may also be used. The polymer latex obtained by the emulsion polymerization method is coagulated and dried by a known method. When blending and dispersing the obtained multi-structure methacrylic resin [] into a methacrylic resin [], a melt-mixing method is ideal. Prior to melt mixing, if necessary, stabilizers, lubricants, plasticizers, dyes and pigments, fillers, etc. are added in addition to the resin composition, and V
After mixing with a mold blender or Henschel mixer, the mixture is melt-kneaded at 150°C to 300°C using a mixing roll, screw extruder, etc. By molding the composition thus obtained using an extrusion molding machine, an injection molding machine, etc., a molded article having excellent transparency, surface gloss, and high impact resistance can be obtained. The present invention will be explained in more detail below based on Examples. In the examples, parts represent parts by weight, and % represents weight %. Example 1 (1) Production of hard crosslinked resin (A) Raw materials in the following proportions were charged into a stainless steel reaction vessel with an internal volume of 50 mm, nitrogen was blown into the container to make it substantially free from the influence of oxygen, and then stirred. Under
Polymerization was carried out at 65°C for 2 hours to obtain a hard crosslinked resin latex. Methyl methacrylate (MMA) 97 parts Methyl acrylate (MA) 1 part Tetraethylene glycol diacrylate (C4 _- DA) 2 parts Sarcosinate LN (S-LN) 0.6 parts Deionized water 150 parts Potassium persulfate (KPS) 0.3 Part Boric acid 1.0 part Sodium carbonate 0.1 part The polymerization rate of MMA in this latex is 98.5%,
The particle size was 0.15 μm. (2) Production of multi-layered acrylic elastomer [] by polymerization of crosslinked acrylic acid ester copolymer (B) A part of the crosslinked resin latex obtained by the polymerization in (1) above is made into another stainless steel. Add rongarit and sarcosinate to the reactor.
After adding an aqueous solution of LN and raising the temperature to 70°C, an acrylic acid ester monomer mixture having the following composition ratio was added continuously at an addition rate of 30 parts/hour,
After the addition was completed, polymerization was continued for another 180 minutes to polymerize the crosslinked acrylic ester copolymer (B) to obtain a multi-layered acrylic elastomer containing a hard crosslinked resin inside the particles in the form of latex. . Hard crosslinked resin latex (as a solid)
20 parts Sarcosinate 0.2 parts Rongarit 0.32 parts Deionized water 120 parts Butyl acrylate (BA) Styrene (ST) BDMA ACM82.5% 15.7% 0.6% 1.2% 80 parts The polymerization rate of BA in this polymerization is 98%, the polymerization rate of ST is 99%, and the particle size of the obtained latex is
It was 0.25 μm. (3) Production of multi-structure methacrylic resin [] by polymerization of monomer mixture (C) Latex equivalent to 100 parts solids of multi-structure acrylic elastomer [] obtained in (2) above is placed in a reaction vessel. After adding 225 parts of deionized water and 0.25 parts of sarcosinate LN to this and stirring, the temperature was raised to 80°C, and the following monomer mixture (C) was continuously added at a rate of 40 parts/hour. . Thereafter, polymerization was continued for an additional hour. Then, a multi-structure methacrylic resin [] was obtained in the form of latex. The polymerization rate of monomer mixture (C) was 99.5% or more. Monomer mixture (C) MMA MA n-C ₈ SH96.6% 3% 0.4% 150 parts This latex was coagulated, washed and dried by the method described below to obtain a powder of multi-structure methacrylic resin [] . Pour 1200 parts of 1.0% sulfuric acid water into a stainless steel container, raise the temperature to 70°C with stirring, and continuously add 600 parts of the latex prepared earlier over 15 minutes.
Thereafter, the internal temperature was raised to 90°C and maintained for 5 minutes. After cooling to room temperature, the polymer was separated and washed with deionized water to obtain a white creamy polymer.
It was dried under the conditions of ℃×24 hours to obtain a white powdery polymer. Next, 250 parts of the powder of the multi-structure methacrylic resin obtained in (3) above and 250 parts of acrylic resin [] (Acrypet VH, a product of Mitsubishi Rayon Co., Ltd.) were mixed in a Henschel mixer, and then Diameter 40mmφ
Screw-type extruder (manufactured by Japan Steel Works, Ltd., P-40)
-26AB-V type, L/D = 26), the content of the multi-layered acrylic elastic body [] is 20% by melt-kneading and pelletizing at a cylinder temperature of 200 to 270°C and a die temperature of 260°C. % impact resistant methacrylic resin composition was obtained. This was injection molded under the following conditions, and the evaluation results shown in Table 1 were obtained from the test pieces obtained. Injection molding machine: V-17-65 screw type automatic injection molding machine manufactured by Japan Steel Works, Ltd. Injection molding conditions: Cylinder temperature 250℃, injection pressure 700
Kg/cm ² Specimen size: 110mm x 110mm x 2mm (thickness) 70mm x 12.5mm x 6.2mm (thickness)

[Table] Examples 2 to 3, Comparative Examples 1 to 2 All Examples except that the amount of sarcosinate LN used in the production of the hard crosslinked resin (A) of Example 1 was changed as shown in Table 2. An impact-resistant methacrylic resin composition was obtained according to Example 1. The resulting impact-resistant methacrylic resin composition was injection molded under the same conditions as in Example 1, and the evaluation results shown in Table 2 were obtained. Table 2 shows the particle diameter of the latex at the stage of the double structure acrylic elastic body [ ].

【table】

Claims (1)

[Scope of Claims] 1. An acrylic acid alkyl ester containing 5 to 50 parts by weight of a hard crosslinked resin (A) containing 80% by weight or more of methyl methacrylate units inside the particles, and in which the alkyl group has 1 to 8 carbon atoms. 69.9 to 89.9% by weight of at least one of the above, 10 to 30% by weight of styrene alone or a mixture of styrene and its derivatives, and the following formula: or 0.1 to 10% by weight of at least one substance shown in
In the presence of 100 parts by weight of a multi-layered acrylic elastomer with a particle size of 0.2 to 0.45 μm, which constitutes the outer layer, 95 to 50 parts by weight of a crosslinked acrylic ester copolymer (B) of a monomer mixture consisting of , methyl methacrylate
80 to 100% by weight, at least one acrylic acid alkyl ester having an alkyl group of 1 to 8 carbon atoms, 0 to 100% by weight;
Obtained by polymerizing 10 to 1000 parts by weight of a monomer or monomer mixture (C) consisting of 20% by weight and 0 to 10% by weight of other vinyl monomers copolymerizable with this monomer. Multi-structure methacrylic resin [] and
A methacrylic resin [] which is a polymer of 80 to 100% by weight of methyl methacrylate and 0 to 20% by weight of vinyl or vinylidene monomer is blended, and 1 to 70% by weight of a multi-structure acrylic system is added to the composition. A methacrylic resin composition containing an elastic body and having excellent impact resistance.