JPS6160749A - Solvent-resistant methacrylate resin composition - Google Patents

Abstract

PURPOSE:To provide a methacrylate resin compsn. having improved solvent resistance, by blending a graft copolymer obtd. by polymerization in the presence of an enlarged rubbery copolymer latex, with a methacrylate resin. CONSTITUTION:20-500pts.wt. monomer mixture cong. 60-100wt% methyl methacrylate monomer is polymerized in the presence of 100pts.wt. latex of a rubbery copolymer (I') enlarged by adding 0.1-5pts.wt. alkali metal salt of an oxyacid of an element of the second and third periods of Groups IIIA to VIA, to 100pts.wt. (on a polymer basis) latex of an emulsion-polymerized rubbery copolymer (I) contg. 30-70wt% C2-C14 alkyl acrylate unit and 70-30wt% 1,3-butadiene unit, to obtain a graft copolymer (II). The copolymer (II) is blended with a methacrylate resin (III) in such a proportion that the resulting compsn. contains 0.1-9.5wt% enlarged rubber copolymer (I'), thus obtaining the desired resin compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a methacrylic resin composition having excellent solvent resistance.

[Conventional technology]

Methacrylic resin is a polymer whose main constituent unit is methyl methacrylate, and it has excellent transparency and optical properties among plastic materials, as well as excellent surface gloss, moldability, mechanical properties, etc. It is excellent. Taking advantage of these properties, it is used in a wide variety of fields, including lighting, signboards, window materials, optical lenses, vehicle parts, and displays.

However, when methacrylic resin comes into contact with organic solvents such as kerosene and paint thinner, it can cause crazes and cracks, for example when printing or painting with ink containing organic solvents such as thinner, or when used in oil gauges for stoves, etc. The field of application is limited because cracks occur, which not only impairs the elegant appearance that is one of the original characteristics of methacrylic resin, but also deteriorates mechanical properties.

As a method of imparting solvent resistance to methacrylic resin, several proposals have been made so far, such as a method of copolymerizing methyl methacrylate and acrylic ester when obtaining solvent-resistant methacrylic resin (Japanese Patent Publication No. 32669/1989). ) and methyl methacrylate alone, or a mixture thereof with a copolymerizable monomer, a chain transfer agent is added to the reaction system from the start of polymerization to the end of polymerization, and the average A method has been proposed in which the ratio between the molecular weight and the average degree of polymerization is set within a certain range (Japanese Patent Publication No. 7845/1984). However, in the former method, thermal properties such as heat distortion temperature and mechanical strength are reduced, and in the latter method, solvent resistance is insufficient.

Other methods include annealing the injection molded product at a moderate temperature to reduce residual molding distortion, and extending the molding cycle in the case of injection molding. Both have problems of low productivity and insufficient solvent resistance.

[Problem that the invention seeks to solve]

Under the above-mentioned current situation, a methacrylic resin that has added solvent resistance without sacrificing the original properties of methacrylic resin, such as transparency, appearance, mechanical properties, thermal properties, and moldability. with the purpose of providing
As a result of extensive studies, it was discovered that by adding a specific amount of a substance having a specific composition and structure to a methacrylic resin, a composition that meets the above objectives can be obtained, and the present invention has been achieved.

[Means for solving problems]

The methacrylic resin composition having excellent solvent resistance according to the present invention includes (a) 30 to 70% by weight of acrylic acid alkyl ester units whose alkyl group has 2 to 12 carbon atoms, and 70 to 30% by weight of 1,3-butadiene units. weight t%, and other monofunctional or polyfunctional vinyl monomer units copolymerizable with these 30
Emulsion-polymerized rubbery copolymer [I
] Per 100 parts by weight of the polymer content of the latex, (oxygen containing mainly elements selected from the group of elements belonging to the second and third periods of Groups 1A to VIA in the Periodic Table of the Elements) alkali metal or alkaline earth metal salts of acids,
The rubbery copolymer [I] latex is enlarged by adding 0.1 to 5 parts by weight of at least one oxyacid salt selected from salts of zinc, nickel, and aluminum, so that the average particle diameter is 0.1 to 5 parts by weight. in the range of 12 to 0.4 μm, and further in the presence of 100 parts by weight of this enlarged rubbery copolymer [I]' latex, (c) 60 to 100 weight percent of methyl methacrylate monomer units, and this Monomer mixture 20-5 consisting of 40-0% by weight of other monofunctional or polyfunctional monomer units copolymerizable with
The graft copolymer [■] obtained by polymerization is blended with the methacrylic resin [I], and 0.1 to 9.5% by weight of the enlarged rubber-like copolymer is added to the composition. Polymer [engineering]
This is a composition characterized by containing '.

As mentioned above, the most important feature of the present invention is that acrylic acid alkyl ester and 1,3-butadiene, which have a relatively low glass transition point (T/), are used as the main copolymerization components as a rubbery copolymer. In these composition ratios, an alkyl acrylate unit with excellent weather resistance is used as an essential component, 1,3-butadiene with excellent rubber properties is used within a range that does not affect weather resistance, and solvent resistance is improved. In order to improve the performance, a rubber-like copolymer is enlarged using a substance with the special structure shown above to obtain a specific particle size range, and then a hard resin component is grafted to form a graft copolymer. This method involves blending and dispersing the graft copolymer with other methacrylic resin.

The rubbery copolymer [I] has an alkyl group having 2 to 12 carbon atoms.
30-70% by weight of acrylic acid alkyl ester of
．． 70-30% by weight of 3-butadiene and 30% of other copolymerizable monomers. It is obtained by emulsion polymerization of a monomer mixture consisting of -0% by weight. The acrylic acid alkyl ester used here is preferably butyl acrylate.

It is 2-ethylhexyl acrylate. Same (other copolymerizable monomers include styrene, acrylonitrile, methacrylic acid alkyl esters such as methyl methacrylate, monofunctional monomers such as cyvinylbenzene, ethylene glycol dimethacrylate, butylene) These are polyfunctional monomers such as glycol diacrylate, triallyl cyanurate, triallyl isocyanurate, trimethylolpropane triacrylate, and pentaerythritol tetraacrylate.

The particle size of the rubbery copolymer C1) obtained by emulsion polymerization is preferably in the range of 0.03 to 0.20 μm, and 0.0
The range of 5 to 0.15 μm is more preferable.

Outside this range, it will be difficult to control the polymerization rate and polymerization temperature, the desired particle size will not be achieved during the subsequent enlargement process, the polymerization system will become unstable, and the impact resistance of the final composition will deteriorate. Problems such as deterioration of appearance may occur.

Alkali metal salts or alkaline earth metal salts of oxyacids mainly containing elements selected from the group of elements belonging to the second and third periods of Groups 11A to VIA of the Periodic Table of the Elements;
At least one oxyacid salt selected from salts of zinc, nickel and aluminum is added to the rubbery polymer (1).
) Used as a thickening agent for latex.

A specific example of such an oxyacid is sulfuric acid.

Examples include salts of nitric acid, phosphoric acid, etc., and potassium, sodium, magnesium, calcium, nickel, and aluminum. Preferred examples include potassium sulfate, sodium sulfate, magnesium sulfate, aluminum sulfate, sodium phosphate, and magnesium phosphate.

The oxyacid salt is added to the rubbery copolymer CD.

The amount of the oxyacid salt added is 0.1 to 5 parts by weight, preferably 0.1 to 4 parts by weight, per 100 parts by weight of the base rubber [I]. By adding an appropriate amount, the base rubber can be enlarged more efficiently, and the stability of the obtained large particle diameter rubber latex can also be greatly improved. However, if the amount is excessive, the polymerization system will solidify, making it impossible to carry out stable polymerization, and therefore, the composition of the present invention cannot be obtained.

Rubbery copolymer [I] enlarged in this way
' has an average particle diameter in the range of 0.12 to 0.4 μm. This enlarged rubbery copolymer [I]' has an optimum range in order to achieve the object of the present invention, and the effect of imparting solvent resistance to methacrylic resin is mainly due to this enlarged rubbery copolymer. This is thought to be due to the polymer [l]'.

That is, when the acrylic acid ester unit is as large as 70% by weight or more in the enlarged rubbery copolymer,
The effect of developing solvent resistance is small, and weather resistance also decreases when the content of 1,3-butadiene units exceeds 70% by weight. If the nine-average particle diameter is outside the above range, the effect of developing solvent resistance will be small and the surface appearance of the molded product will be poor.

Although the effects of these effects are not clear, they are thought to be related to the compositional structure of the enlarged rubbery copolymer [I]'. Furthermore, by adding a small amount of such a rubbery substance to the methacrylic resin, it is possible to improve solvent resistance by reducing molding distortion and reducing distortion due to stress caused by infiltration of various solvents.

The graft copolymer CI+) is produced by adding 60 to 100% by weight of methyl methacrylate and a vinyl monomer copolymerizable therewith in the presence of 100 parts by weight of the enlarged rubbery copolymer (1). Monomer mixture 20 consisting of 40-01% by weight
It is obtained by polymerizing ~500 parts by weight.

Other vinyl monomers copolymerizable with methyl methacrylate are not particularly limited, but preferably include alkyl acrylates, styrene, acrylonitrile, and the like.

In the monomer mixture, when methyl methacrylate is less than 60% by weight, the effect of developing solvent resistance is small, and
If the monomer mixture for the enlarged rubbery copolymer latex [I]' is outside the above range, the appearance and solvent resistance of the final molded product will be poor, or the productivity will be reduced.

The polymerization temperature during the emulsion polymerization to obtain the rubbery copolymer [I] and the graft copolymer C1) up to the production of the graft copolymer [11) is 30 to 120°C.

More preferably, the temperature is 50 to 100°C, and the polymerization time depends on the type and amount of the polymerization initiator and emulsifier.

Although it varies depending on the polymerization temperature and the like, it is usually 0.5 to 24 hours at each polymerization stage.

The ratio of polymer to water is preferably monomer/water=1/20 to 1/1.

The polymerization initiator and emulsifier can be added to either or both of the aqueous phase and the monomer phase.

In the polymerization of the rubbery copolymer (1) and the graft copolymer (1), the monomers can be charged all at once or in portions. In the case of polymerizing the combined Cl), the split charging method is more preferable in terms of polymerization heat generation and the like.

The emulsifier does not need to be particularly limited as long as it is a commonly used emulsifier; examples of emulsifiers that can be used include long chain alkyl carboxylates, sulfosuccinic acid alkyl ester salts,
Alkylbenzene sulfonate, etc.

There is no need to particularly limit the type of polymerization initiator; 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. You can also do that. Redox initiation systems such as organic hydroperoxide-ferrous salts, organic hydroperoxide dosodicum sulfoxylate, benzoyl peroxide, and azobisisobutyronitrile may also be used.

The polymer latex of the graft copolymer (II) obtained by the emulsion polymerization method is coagulated and dried by a known method.

Methacrylic resin [1] is methyl methacrylate monomer 6
0-100% by weight of other vinyl monomers copolymerizable with 40
~0% by weight of the polymer.

Other copolymerizable vinyl monomers include acrylic acid alkyl esters in which the alkyl group has 1 to 4 carbon atoms, styrene, and acrylonitrile.

Methacrylic resin [I] Medium K, thickened rubbery copolymer [I
]', and the enlarged rubbery copolymer [I]' is added to the resulting composition in an amount of 0.1 to 9.5% by weight, particularly preferably 0.
．． Contain 5 to 5.0% by weight. If it is less than 0.1% by weight, the effect of developing solvent resistance is small, and 9.5% by weight! If it exceeds t%, no further improvement in solvent resistance can be expected, and thermal and mechanical properties, transparency, hardness, etc. will deteriorate.

The obtained graft copolymer [■] was mixed with methacrylic resin [I
], the ideal method is melt mixing. Prior to melt-mixing, in addition to the resin composition, traps, stabilizers, lubricants, plasticizers, dyes, pigments, fillers, etc. are added as necessary and mixed using a v-o blender, Henschel mixer, etc., followed by mixing rolls and a set of screws. Melt kneading is performed at 150 to 300°C using an extruder or the like.

The composition thus obtained can be molded using an extrusion molding machine or an injection molding machine to obtain a molded product having excellent solvent resistance, transparency, and high surface gloss.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on Examples.

In addition, in the examples, parts represent parts by weight, and % represents weight %.

Example-1, Comparative Example-1 Production of rubbery copolymer Cjl Butyl acrylate 6kli+1.
3-Butadiene 4 Diisopropylbenzene hydroperoxide 20/Potassium tallow fatty acid 100 Sodium N-lauroyl sarcosinate 5ON Sodium pyrophosphate 50 Ferrous sulfate
0.5〃Dextrose
30 deionized water 20 kg Among the substances with the above composition ratio, remove 1,3-butadiene (for the substance, replace the oxygen contained in it with nitrogen,
A state was established in which the polymerization reaction was not substantially inhibited. The material was then charged into a 40 autoclave and polymerized at 50°C. Polymerization was completed in 9 hours, and a rubber latex with a conversion rate of 97% and a particle size of 0.07 μm was obtained.

Adjustment of enlarged rubbery copolymer [I]' A rubbery copolymer (1
) While stirring the 601 autoclave containing the latex, 1.5 units of an aqueous solution of 10% sulfuric acid as an oxyacid was added at an internal temperature of 50°C and held for 15 minutes.

The average particle diameter of the obtained enlarged rubbery polymer [I]' was 0.
．． It was 125 μm.

Graft copolymer C1) Production of latex Into an enlarged reaction vessel containing enlarged latex containing polymer solid content of 10k17 of enlarged rubbery copolymer [I]',
9 kg of deionized water, 20 t of sodium formaldehyde sulfoxylate, and 50 I of sodium N-lauroyl sarcosinate were added, the internal temperature was raised to 75°C, and the following raw materials were continuously added over 90 minutes for polymerization.

Methyl methacrylate 4320 / Ethyl acrylate 180 J' Normal octyl mercaptan 6,757 Cumene hydroperoxide 16 After the addition of P, polymerization was continued for an additional 60 minutes, and the conversion rate of methyl methacrylate was approximately 100%.

Styrenated phenol 5 was added to the obtained polymer latex.
8P, dilaurylthiopropione) 447. ) Riphenylphosphite 58J' was added and 0.25% sulfuric acid water (from latex/water = 1/
2 and further held at 85°C for 5 minutes.

The obtained slurry polymer was washed and dehydrated and heated at 65°C for 3
After drying for 6 hours, a white powder was obtained.

This powder resin (:II) '+0.45 to 9 and methacrylic resin (Acryvet MD; Mitsubishi Rayon Co., Ltd. product)
9.55kF, stearin monoglyceride 1011
Ultraviolet absorber (Tinuvin-P/Sano-/I/Ls770
;Ciba Geigy/Sankyo Co., Ltd. products') 20 P/3
0 P and 20! The mixture was mixed using a large-capacity Henschel mixer, and then a 30 m x φ twin-screw extruder (manufactured by Ikegai Iron Works
CM-30) at a temperature of 230-250°C,
It was pelletized at a rotation speed of 250 rpm. This pellet-shaped resin was molded using a screw injection molding machine (Nippon Steel New Co., Ltd.; Ankelberg V-17-65 type) at a cylinder temperature of 250°C and an injection pressure (gauge pressure) of 50'Q/am''.
10X110X2 (thickness) 1nIL and 70x12,5x
6.2 (Thickness) A test of mx was prepared and the evaluation results shown in Table 1 were obtained.

As can be seen from this result, the composition according to the present invention exhibits excellent solvent resistance and transparency.

Good thermal properties, hardness, and weather resistance.

*l) 110XI 10X2 (thickness) A molded product of one blade was immersed in a solvent at 30° C. for 10 minutes, and the surface condition was observed.

*2) Measured in accordance with ASTM-D-1003-52.

*3) Measured in accordance with ASTM-D-696.

*4) Measured in accordance with ASTM-D-785.

*5) Sunshine Weather Meter (WEL-8U
The degree of coloring was determined visually after exposure for 1000 hours using N-DC type, Suga Test Instruments) K.

*6) T P -T -266B (Japan Special Paints (
Co., Ltd. product) *7) Methacrylic resin Niacrypet MD, Mitsubishi Rayon Co., Ltd. Product Example-2, Comparative Example-2 The composition 2 ratio of graft copolymer [■] and the type of methacrylic resin El) are shown in the table. A composition was produced in exactly the same manner as in Example 1, except for the changes as in Example 2, and its properties were evaluated.

Table 3 shows the evaluation results.

Examples-3 to 4. Comparative Examples 3 to 5 Compositions were produced in the same manner as in Example 1, except that the composition ratios of the rubbery copolymer [I] and the monomer mixture were changed as shown in Table 4. Table 5 shows the evaluation results of the characteristics.

The results in Table 5 show the following.

Compared to the compositions according to the present invention (Examples 3 and 4), the composition containing only acrylic ester as a rubber component has a poorer solvent resistance improvement effect (Comparative Example 3).

A rubber composition containing only 1,3-butadiene inhibits transparency and has poor weather resistance (Comparative Example 4).

When the amount of the monomer mixture used is small, there is no effect of improving solvent resistance and transparency also decreases (Comparative Example-5).

Examples-5 to 6. Comparative Examples-6 to 8 Graft copolymer CII"1 produced in Example-1,
A composition was obtained by mixing the methacrylic resin (1) and the rubbery copolymer [l]' in such a manner that the content thereof was as shown in Table 6. The evaluation results are shown in Table-6.

From this result, the composition with a small amount of additives of enlarged rubbery copolymer [I]' has no effect on solvent resistance (Comparative Example-6)
If the amount added is large, the solvent resistance will be improved, but the original properties of the methacrylic resin will be lost.

Examples-7 to 10. Comparative Examples 9 to 10 Compositions were produced in exactly the same manner as in Example 1, except that the type of oxyacid salt and the amount added were changed as shown in Table 7, and the properties thereof were evaluated.

Table 7 shows the evaluation results.

〔Effect of the invention〕

As mentioned above, in order to have excellent solvent resistance, the solvent-resistant methacrylic resin composition of the present invention is formed into a plate shape or other shape, heat-processed or drilled, and then brought into contact with various solvents. It does not crack at all and has the same transparency and physical properties as existing methacrylic resins, so it can be used in a wide variety of applications.

Claims (1)

[Scope of Claims] 1. (a) 30 to 70% by weight of acrylic acid alkyl ester units whose alkyl group has 2 to 12 carbon atoms, 70 to 30% by weight of 1,3-butadiene units, and copolymerizable with these. Other monofunctional or polyfunctional vinyl monomer units 3
Emulsion-polymerized rubbery copolymer consisting of 0 to 0% by weight [
[I] Based on 100 parts by weight of the polymer content of the latex, (b) Oxygen acid containing mainly elements selected from the group of elements belonging to the second and third periods of Groups IIIA to VIA of the Periodic Table of Elements. alkali metal salts or alkaline earth metal salts,
The rubber-like copolymer [I] latex is enlarged by adding 0.1 to 5 parts by weight of at least one oxyacid salt selected from salts of zinc, nickel, and aluminum, so that the average particle diameter is 0.12 to 5. 0.4 μm range, and further in the presence of 100 parts by weight of this enlarged rubbery copolymer [I]' latex, (c) 60 to 100% by weight of methyl methacrylate monomer units, and copolymerized with this. a monomer mixture consisting of 40 to 0% by weight of other monofunctional or polyfunctional monomer units of 20 to 5% by weight;
The graft copolymer [II] obtained by polymerization is blended with the methacrylic resin [III], and 0.1 to 9.5 parts by weight of the enlarged rubbery copolymer is added to the composition. Polymer [
A solvent-resistant methacrylic resin composition characterized by containing I]'. 2. Solvent resistance according to claim 1, characterized in that the resin composition contains 0.5 to 5.0% by weight of the enlarged rubbery copolymer [I]'. Methacrylic resin composition.