JPS59187012A - Manufacture of thermoplastic resin - Google Patents

Abstract

PURPOSE:To obtain titled resin with high weatherability and transparency and impact resistance, by the graft polymerization, to an ethylene-propylene-nonconjugated diene copolymer rubber, of a vinyl monomer mixture which contains acrylic alkyl ester and satisfies a specific condition. CONSTITUTION:A graft polymerization is carried out in a conventional way between (A) 10-70pts.wt. of an ethylene-propylene-nonconjugated diene copolymer rubber and (B) 90-30pts.wt. of a mixture of an acrylic alkyl ester (e.g., n-propyl acrylate) and another vinyl monomer copolymerizable with it (e.g., styrene). In this process, the composition of the mixture (B) should be selected so that the difference of the refractive index of the polymer consisting of said mixture (B) alone and that of the rubber (A) falls <=0.005.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a thermoplastic resin having excellent weather resistance, impact resistance and transparency.

Although polymethyl methacrylate (PMMA) resin is used in a wide range of fields as an excellent transparent resin, it has the drawback of low impact strength. As a method for imparting impact resistance to these transparent resins, a vinyl monomer mixture consisting of methyl methacrylate, styrene, acrylonitrile, etc. is added to a diene rubber in the presence of a diene rubber such as polybutadiene (PBD). A method of polymerizing by selecting the composition of a vinyl monomer mixture so that the refractive index of the vinyl monomer mixture and the refractive index of the polymer obtained by polymerizing the vinyl monomer mixture alone are substantially the same (Japanese Patent Publication No. 42 19248, Japanese Patent Publication No. 44-19547, and Japanese Patent Publication No. 44-2229), for example, methyl methacrylate-butadiene-styrene copolymer resin (MBS resin) and methacrylic acid methyl /L=-7ri+) Ronitrile-butadiene-styrene copolymer resin (vfABS resin) is used in various fields, but these resins deteriorate and discolor due to ultraviolet rays and oxygen in the air. However, it has a fatal drawback of poor weather resistance.

On the other hand, as a method of imparting weather resistance to impact-resistant resin,
The base rubber is a diene rubber, and 9 is an ethylene-propylene-nonconjugated diene copolymer rubber (hereinafter referred to as EPDM).
A number of methods are known, for example, using aromatic vinyl monomers in the presence of E, PDM rubber.
/ A method for producing an impact-resistant resin with excellent weather resistance by polymerizing a vinyl monomer mixture with an unstable composition, such as an annated vinyl monomer and a methacrylic acid alkyl ester monomer ( For example, Tokuko Sho 52-30549
Publication No. 52-18751, Japanese Patent Publication No. 56-56
0906) and a method of polymerizing a methacrylic acid alkyl ester monomer represented by methyl methacrylate in the presence of EPDM rubber for the purpose of further increasing heat aging resistance and ozone resistance (Japanese Patent Publication No. 51-0906). 4748
6 and Japanese Patent Publication No. 52-15112) have been proposed. However, although the graft copolymers obtained by these methods have excellent impact resistance and weather resistance, the refractive index of a polymer consisting only of a monomer mixture or a meta-acid alkyl ester monomer is
The refractive index is significantly higher than that of PDM, resulting in inferior transparency.
It has the disadvantage that it cannot be used in applications that require transparency.

Therefore, the present inventors conducted extensive research with the aim of developing a thermoplastic resin with an excellent balance of weather resistance, impact resistance, and transparency. As a result, the present inventors developed a thermoplastic resin based on an EPDM coating and an acrylic acid alkyl ester monomer. The inventors have discovered that a thermoplastic resin that fully meets the above objectives can be obtained by graft polymerizing a vinyl monomer mixture that is contained as an essential component and satisfies specific conditions, and has thus arrived at the present invention.

That is, the present invention provides (a) EPDM rubber 10 to
When graft polymerizing 90 to 30 parts by weight of a monomer mixture consisting of (b) an acrylic acid alkyl ester monomer and another vinyl monomer copolymerizable therewith in the presence of 70 parts by weight, (+ )) The difference between the refractive index of the polymer obtained by polymerizing only the monomer mixture and the refractive index of (a) EPDM rubber 9 is
The present invention provides a method for producing a thermoplastic resin, characterized in that the composition of (b) the monomer mixture is selected so that the ratio is 0.005 or less.

When EPDM rubber is used as a base rubber, conventional vinyl monomers such as aromatic vinyl monomers, vinyl cyanide monomers, and alkyl methacrylate monomers are used. Even if only EPDM rubber is used as a monomer component, the refractive index of EPDM rubber is significantly lower than that of the matrix resin component, so it is not possible to produce a transparent resin from a combination of the two. Since the refractive index of the polymer consisting of the above-mentioned polymer is extremely lower than that of the above-mentioned ordinary matrix resin component, in the present invention, an acrylic acid alkyl ester monomer is used as an essential component of the vinyl monomer mixture. By using this, it is possible to substantially match the refractive index of the EPDM rubber and the refractive index of the matrix resin component, and as a result, a thermoplastic resin with good transparency and excellent weather resistance and impact resistance can be created. Manufacturing becomes possible.

The EPDM rubber used in the present invention is usually ethylene 2
A copolymer rubber consisting of 0 to 90 moles of propylene and 80 moles of propylev is suitable. These EPDM
The Mooney viscosity of the rubber is preferably 20 to 200. Here, as the non-conjugated diene, cyclic dienes such as norbornenes and cyclopentadiene, or non-conjugated chain dienes such as t4-hexadiene are used.

The acrylic acid alkyl ester used in the present invention (in the formula represents alkyl having 1 to 8 carbon atoms), and specific examples include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, It is also possible to use pentyl acrylate, heptyl acrylate, heptyl acrylate and acrylic acid, among which n-propyl acrylate and butyl acrylate are particularly preferred.

Examples of other vinyl monomers that can be copolymerized with the acrylic acid alkyl ester monomer include aromatic vinyl monomers such as styrene, α-methylstyrene, and vinyltoluene, and acrylonitrile and methacrylonitrile. Examples include vinyl cyanide monomers and methacrylic acid ester monomers such as methyl methacrylate and ethyl methacrylate.

In the present invention, when only an acrylic acid alkyl ester monomer is used as a vinyl monomer to be graft-polymerized with EPDM rubber, the refractive index of the matrix resin component is smaller than that of EPDM, so that transparent thermoplastic When a resin is not obtained, the difference between the refractive index of the matrix resin and the refractive index of EPDM is 0.0 by using a mixture of the other vinyl monomers and the acrylic acid alkyl ester monomers mentioned above.
It is necessary to appropriately select the composition of the monomer mixture so that it is 0.05 or less. Here, the difference in refractive index between the two is 0.005
If it exceeds 20%, the transparency of the thermoplastic resin obtained will decrease, which is not preferable. The refractive index of the IJ lux resin, which is composed only of a monomer mixture, can be calculated from a theoretical formula or can be known by measuring the refractive index of a resin obtained by polymerizing a monomer mixture having the same composition in advance. I can do it.

(a) E PD when producing the thermoplastic resin of the present invention
The ratio of M rubber and (b) monomer mixture is (a) 10~
70 parts by weight, especially 15 to 50 parts by weight b) 9
0 to 60 parts by weight, especially 85 to 50 parts by weight (total 100 parts by weight)
(parts by weight) is preferred, and (a) EPDM is 10
If it is less than 70 parts by weight, the grafting rate is low and a resin with insufficient impact resistance is obtained, and if it exceeds 70 parts by weight, the moldability and transparency of the resin deteriorate, which is not preferable.

As the polymerization method for producing the thermoplastic resin of the present invention, known methods such as solution polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization can be employed. Solution polymerization methods and suspension polymerization methods using aromatic/aliphatic hydrocarbon mixed solvents are preferred.

The thermoplastic resin of the present invention thus obtained has excellent weather resistance, impact resistance, and transparency in a well-balanced manner, and is expected to be used in various applications that take advantage of these properties. vinyl polymers, such as styrene
Acrylonitrile-methyl methacrylate copolymer, polymethyl methacrylate, polybutyl acrylate, butyl acrylate-methyl methacrylate copolymer, styrene-butyl acrylate-methyl methacrylate copolymer, styrene-acrylonitrile-butyl acrylate copolymer Polymers, methyl methacrylate-acrylonitrile copolymer, styrene-methyl methacrylate copolymer, styrene-butyl acrylate copolymer and styrene-acrylonitrile-
It can also be put to practical use in the form of a composition containing a methyl methacrylate-butyl acrylate copolymer or the like. However, the vinyl polymer used here preferably has a refractive index difference of 0.0'05 or less from the thermoplastic resin obtained in the present invention, and if this condition is not satisfied, a transparent composition is used. can't get things.

Further, in this case, the blending ratio of the thermoplastic resin of the present invention and the vinyl polymer may be in a wide range of 5 to 95 parts by weight/95 to 5 parts by weight.

The thermoplastic resin of the present invention and the composition using the same may contain hindered phenol groups, phosphorus-based and sulfur-based antioxidants, hindered amine-based light stabilizers, etc.
Conventional additives such as ultraviolet absorbers, lubricants, colorants, flame retardants, reinforcing agents, and fillers can also be incorporated to the extent that they do not impede transparency.

The present invention will be further explained below using reference examples and examples. In this example, the Izod impact strength is AST
Measured according to MD-256-56 Method A. The refractive index was measured at 20° C. using an Atsube refractometer.

The light transmittance was determined by press-molding a sheet with a thickness of 1, and measuring it with a spectrophotometer at a light wavelength of 5807 nm.

The weather resistance test was carried out using a Sun 7 Yain Weather Meter (WEL-8UN-HC model manufactured by Suga Tenken Iso), and the retention rate of 1/8" Izotsu impact strength after 400 hours of exposure [400
Impact strength after time exposure/Impact strength before exposure Xl00.1
The 1/8 Izot impact strength is ASTM
Measured according to I)-256-5-6.

Example 1 Polymers A to F were produced using the following formulations.

(1) E PDM rubber (Mitsui Petrochemical E P
After dissolving 25 parts of T≠3045) in 250 parts of toluene, the system was replaced with nitrogen and 11-butyl acrylate 6
7.5 parts of methyleph, 15 parts of methylene ref, and 0.5 part of benzoyl peroxide were added, and polymerization was carried out at 80° C. for 15 hours. After polymerization is complete, the polymer solution is poured into methyl alcohol to extract and remove unreacted substances, washed with methyl alcohol,
After drying, a graft copolymer was obtained.

Δ (2) EPDM rubber (Mitsui Petrochemicals EP T≠40
70) 15 parts to 100 parts of benzene and 1 part of n-hebutane
After dissolving in 00 parts of mixed solvent, the system was replaced with nitrogen,
Next, 595 parts of n-butyl acrylate, 4.2 parts of styrene
5 parts of acrylonitrile, 21.25 parts of acrylonitrile, and 05 parts of benzoyl peroxide were added, and polymerization was carried out at 80° C. for 8 hours. After the polymerization was completed, the polymer solution was poured into methyl alcohol, unreacted substances were extracted and removed, and after washing with methyl alcohol and drying, a graft copolymer B was obtained.

(3)ll? ! 40 parts of E I) DM rubber (EP T≠3045 manufactured by Mitsui Petrochemicals) and 250 parts of toluene were placed in an autoclave, and after completely dissolving the rubber,
The inside of the system was purged with nitrogen, and then 42 parts of ethyl acrylate, 18 parts of methyl methacrylate, and 0.5 part of dicumyl peroxide were added, and polymerization was carried out at 110° C. for 20 hours.

After the polymerization was completed, the polymer solution was poured into methyl alcohol, unreacted substances were extracted and removed, and after washing with methyl alcohol and drying, a graft copolymer C was obtained.

(4) In an autoclave, 20 parts of EPDM rubber (EPT-≠3045 manufactured by Mitsui Petrochemicals) was mixed with 66.7 g of toluene.
72 parts of methyl acrylate, 1.6 parts of styrene, 6.4 parts of acrylonitrile and 05 parts of benzoyl peroxide were added to this solution and mixed uniformly. Separately, 03 parts of methyl methacrylate/acrylamide-20780 copolymer and 0.05 parts of phosphoric acid/sodium were dissolved in 200 parts of pure water and charged into an autoclave. °C for 6 hours, then at 100 °C for 1 hour.
Polymerization was carried out for a period of time to obtain a colorless and transparent bead-like polymer having an average particle size of 0.5 to 0.8 myn.

(5) E PDM in autoclave
com (Mitsui Petrochemical EPT≠4070125 parts 27
After mixing and dissolving 750 parts of methyl acrylate and 50 parts of rhohebutane, the system was replaced with N and gas, and 60.0 parts of methyl acrylate, 15 parts of acrylonitrile, and 0.5 parts of benzoyl peroxide were added to this solution to homogenize. mixed with.

On the other hand, 0.3 parts of methyl methacrylate/acrylamide-2o,'a OQ copolymer and phosphoric acid/
Melt 0.05 part of sodium, charge it into an autoclave, and heat it at 90°C for 6 hours with vigorous stirring.
C. for 1 hour to obtain bead-like polymer E.

(6) E J) D M rubber (
Mitsui Petrochemical Co., Ltd. E I) T-≠RO045) 20 parts 66.7 parts of ketoluene and 6 parts of 1]-hebutane were charged and dissolved uniformly, then the system was replaced with nitrogen and this solution was 60.0 parts of 11-butyl acrylate, 16 parts of methyl methacrylate, 4 parts of styrene, and 0.5 part of benzoyl peroxide were mixed and dissolved. Next, as a suspension stabilizer, 0.3 parts of methyl methacrylate/acrylamide-2D/80 copolymer, 0.05 parts of monosodium phosphate, and 200 parts of pure water were mixed and added, and the mixture was heated at 90°C for 6 hours with stirring. , and further polymerized at 100°C for 1 hour. After the polymerization was completed, unreacted substances and the solvent were removed by steam distillation, followed by washing with water, dehydration, and drying to obtain bead-shaped polymer F.

Each of the obtained polymers A-F was heated to a resin temperature of 22°C using an extruder.
Each sample was pelletized by extrusion at 0°C. Then, for each pellet, the cylinder temperature was 230°C and the mold temperature was 50°C.
Each test piece was prepared by injection molding under the following conditions, and its characteristics were evaluated. The results are shown in Table 1.

Comparative Example 1 24 parts of styrene and 56 parts of methyl methacrylate in the presence of 20 parts of polybutadiene latex (as solids)
A graft copolymer CG) was obtained by emulsion graft polymerization.

In the presence of the EPDM rubber shown in Table 1, monomers or monomer mixtures having the composition shown in Table 1 were polymerized in the same manner as in the solution polymerization method of graft copolymer (A) in Example 1. Graft copolymers (H+ to (N)) were prepared by polymerization according to the recipe.

Test pieces of these graft copolymers (1-I) to (N) were prepared by injection molding in the same manner as in Example 1, and the properties of the test pieces were evaluated. Table 1 also shows the results.

As is clear from Table 1 below, all of the kraft copolymers (A) to (F') obtained by method 1 of the present invention have a balance of transparency, impact resistance, and weather resistance. ing. On the other hand, E
The graft copolymer (G) using polybutylene diene instead of PDM had extremely poor weathering resistance, and the monomer mixture contained methyl methacrylate instead of the monokylated acrylic ester monomer. In case (H, I, M) and even if the fucryl ester monomer is contained, the difference between the refractive index of the copolymer consisting only of the monomer mixture and the refractive index of EPDI'v is 0.
．． 005 or more (J-L.

All of the graft copolymers (N) have good transparency.

Example 2 By a suspension polymerization method, six types of vinyl copolymers (a) to (f
) was prepared.

□ Next, these vinyl copolymers (a) to (f) i- and the graft copolymers (5) to (F) obtained in Example 1 were mixed in the proportions shown in Table 6. Extruder (2)
After pelletizing at 20° C.), test pieces were prepared by injection molding and their properties were evaluated.

These results are also shown in Table-3.

As is clear from the results in Margin Table 6 below, even in compositions in which the thermoplastic resin obtained by the method of the present invention and the transparent vinyl polymer are blended so that the difference in refractive index between them is within 0.005, , has an excellent balance of transparency, impact resistance, and weather resistance.

Patent applicant: Toshi Co., Ltd.

Claims (1)

[Claims] (a) In the presence of 10 to 70 parts by weight of ethylene-propylene-nonconjugated diene copolymer rubber, (b) a monomer consisting of an acrylic acid alkyl ester monomer and another vinyl monomer copolymerizable therewith. When graft polymerizing 90 to 30 parts by weight of the monomer mixture, (b) the refractive index of the polymer obtained by polymerizing only the monomer mixture and (a) ethylene-propylene-
A method for producing a thermoplastic resin, comprising selecting the composition of (b) the monomer mixture so that the difference in refractive index of the non-conjugated diene copolymer rubber is 0005 or less.