JPH0350212A - Thermoplastic resin composition excellent in weathering and impact resistances - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic resin composition improved in weathering and impact resistances by grafting a monomer selected from specified compounds onto a latex of a compound rubber prepared by polymerizing an acrylic ester-based monomer containing a crosslinking agent, etc., in the presence of a specified copolymer rubber latex. CONSTITUTION:95-10 pts.wt. at least one monomer (i) selected from an aromatic vinyl compound and an ethylenically unsaturated compound of the formula: CH2=CRX (wherein R is H or CH3; and X is CN or COOR<1>, wherein R<1> is a 1-8C alkyl) is polymerized in the presence of 5-90 pts.wt. (in terms of the solid matter) latex of a compound rubber (ii) obtained by polymerizing 10-95wt.% acrylic ester-based monomer containing a crosslinking agent or a crosslinking agent/graft crosslinking agent mixture in the presence of 5-90wt.% (in terms of the solid matter) latex of an ethylene/propylene/nonconjugated diene copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a thermoplastic resin composition having excellent impact resistance and weather resistance.

[Conventional technology]

ABS resin has traditionally been used as a thermoplastic resin with a good balance of impact resistance, thermal/mechanical properties, and moldability, and has been used for light electrical parts,
It is used in various fields such as automobile parts and miscellaneous goods. However, this ABS resin has many chemically unstable double bonds in its main chain because the butadiene-based polymer, which is the rubber component for imparting impact resistance,
It is well known that it is easily degraded by UV rays and has poor weather resistance.

As a method to improve the weather resistance of this ABS resin, a method has been proposed to use a saturated rubbery polymer that has almost no double bonds in the main chain, and a typical example is ethylene-propylene. -Those using non-conjugated diene copolymer rubber are known.

Methods for producing these impact-resistant resins include bulk polymerization (U.S. Pat. No. 3,435,096) and solution polymerization (
US Pat. No. 3,538,190 and US Pat. No. 3,5381
No. 91 Specification) etc. have been proposed.

[Problem to be solved by the invention]

However, the graft copolymer obtained by the production method described in the above specification etc. has weather resistance that is better than that of ABS l'l because it uses ethylene-propylene-nonconjugated diene copolymer rubber as the rubber component. However, the surface appearance and gloss of the molded product are poor, and the weather resistance is poor.
Impact resistance was still insufficient.

In view of the current situation, the present inventors developed a method disclosed in JP-A-63-95211 as a thermoplastic resin composition that provides molded products with excellent weather resistance, impact resistance, and good surface gloss. Proposed. As a result of continued investigation, we found that a composite rubber obtained by polymerizing an acrylic ester by an emulsion polymerization method in the presence of a latex of ethylene-propylene-nonconjugated diene copolymer rubber contains an aromatic vinyl compound, By using a graft copolymer obtained by graft polymerizing one or more types of (meth)acrylic acid alkyl ester and vinyl cyanide compounds, impact resistance is significantly improved, and heat resistance with excellent weather resistance is achieved. It was discovered that a plastic resin composition can be obtained, and the present invention was achieved.

[Means for Solving the Problems] That is, the thermoplastic resin composition of the present invention has ethylene-
10 to 95% by weight of an acrylic ester blended with a crosslinking agent or a mixture of a crosslinking agent and a grafting agent in the presence of 5 to 90% by weight (as solid content) of the latex of propylene-nonconjugated diene copolymer rubber (1) In the presence of 5 to 90 parts by weight (as solid content) of latex of composite rubber (2) obtained by polymerizing % of aromatic vinyl compound and general 2C) 12=CRX (wherein R is H or CH3 At least one monomer selected from the group consisting of ethylenically unsaturated compounds represented by (3) A graft copolymer resin (4) obtained by polymerizing 95 to 10 parts by weight (total amount of (2) and (3) 100% by weight), and
This graft copolymer resin (4) and hard thermoplastic resin (5) are combined into a total resin composition (total amount of (4) and (5)).
The thermoplastic resin composition (4) is a thermoplastic resin composition (4) in which the composite rubber (2) is mixed in a proportion of 5 to 80% by weight.

[Function] The ethylene-propylene-nonconjugated diene copolymer rubber (1) used in the present invention contains ethylene, propylene, and as a third component, for example, dicyclopentadiene, ethylidene norbornene, 1.4-hexadiene, 1.5 -hexadiene, 2-methyl-1,5-hexadiene, 1,4-
It is an ethylene-propylene-nonconjugated terpolymer (hereinafter abbreviated as EPDM) consisting of one or more nonconjugated dienes such as cyclohebutadiene and 1,5-cyclooctadiene.

It is preferable to use one or more of dicyclopentadiene and ethylidene norbornene as the non-conjugated diene component in EPDM.

The molar ratio of ethylene and propylene in EPDM is 5:l
The ratio of unsaturated groups in EPDM is preferably in the range of 4 to 50 in terms of iodine value.

Although there are no particular restrictions on the method for producing EPDM latex, it is common to apply mechanical shearing force to EPDM in the presence of an emulsifier to stabilize fine dispersion in water to form a latex.

The particle size of the EPDM latex is preferably in the range of 0.05 to 2 μm. If it is less than 0.05 μm, sufficient impact strength will not be developed, and if it is more than 2 μm, polymerization will become unstable and the resulting graft polymer resin will have poor gloss. It tends not to occur.

The EPDM used in the present invention must be crosslinked.

When a non-crosslinked material is used, the development of impact strength is poor, and when molded at high temperatures, significant defects occur in the appearance of the molded product. When the degree of crosslinking is expressed in terms of gel content, it is preferably in the range of 30 to 95%. 30%
If it is less than 95%, the molding anisotropy will be significant and the gloss of the molded product will be poor; if it is more than 95%, the impact strength will be poor.

The latex of E PDM (1) may contain one or more other rubbers having a low fi (31% by weight or less) depending on the purpose. Examples of such rubbers include polybutadiene, polyisoprene, styrene-butadiene rubber. Other rubbers may be blended in this way, but to improve weather resistance, EPD in rubber latex
The higher the proportion of M, the more preferable.

In the presence of 5-90% by weight (as solid content) of EPDM latex, 10-95% by weight of a monomer based on an acrylic ester blended with a cross-linking agent or a mixture of a cross-linking agent and a grafting agent, in a total amount is added to the latex all at once, in portions, or continuously, and polymerized in the presence of a radical polymerization initiator to produce EPDM rubber (1).
A composite rubber (2) is obtained in which a crosslinked acrylic ester copolymer is formed on the outer layer of particles.

The acrylic esters used here include alkyl esters in which the esterification moiety has an alkyl group of 1 to 12 carbon atoms such as methyl, ethyl, n-propyl, 2-ethylhexyl, and n-lauryl; chloroethyl acrylate; Herooalkyl esters such as: aromatic esters such as benzyl acrylate and phenethyl acrylate.

In addition, examples of copolymerizable monomers that may be used in combination with the above acrylic ester include methacrylic acid alkyl esters such as methyl methacrylate and butyl methacrylate;
Examples include acrylonitrile: styrene, and these are optionally used in an amount of 20% by weight or less of the crosslinked acrylate copolymer.

The grafting cross-agent used in the present invention refers to a compound that has 2 to 3 unsaturated groups having addition polymerizability, and each unsaturated group has a large difference in polymerization reactivity.Specific examples include acrylic Examples thereof include allyl esters of unsaturated acids such as methacrylic acid, maleic acid, fumaric acid, cyanuric acid, and isocyanuric acid. In addition, the crosslinking agent used in the present invention refers to a compound that has a plurality of unsaturated groups having addition polymerizability, and the polymerization reactivity of each unsaturated group is approximately the same or has a small difference,
Specific examples include diacrylic acid ester or dimethacrylic acid ester of polyalkylene glycol, divinylbenzene, and the like.

As a polymerization initiator, a thermal decomposition type initiator such as potassium persulfate or ammonium persulfate, or a redox type initiator such as a sugar-containing birophosphate formulation which is a combination of cumene hydroperoxide-iron compound-sodium birophosphate dextrose is used. can be used. tert-butyl hydroperoxide instead of cumene hydroperoxide,
Diimpropylbenzene hydroperoxide and the like can also be used. It is also possible to use sodium salt of ethylenediaminetetraacetic acid (EDTA-2Na) instead of sodium birophosphate. It is also possible to use sodium formaldehyde sulfoxylate instead of dextrose.

The graft polymer resin (4) of the present invention is prepared by adding an aromatic vinyl compound and a general 2 GHz= CRX C In the formula, R is H or CL,
X represents CN or C0OR'. However, lit is an alkyl group having 1 to 8 carbon atoms. ) At least one monomer selected from the group consisting of ethylenically unsaturated compounds represented by (3) 95 to 10% by weight ((2) and (
The total amount of monomer (3) (100% by weight) is added to the latex in the presence of a radical polymerization initiator at once, in portions, or continuously to perform graft polymerization. be done.

As the polymerization initiator, those exemplified in the production of composite rubber (2) can be used.

During graft polymerization, it is preferable to add an additional emulsifier to stabilize the polymerization. As the emulsifier, any anionic emulsifier that can be used in normal emulsion polymerization can be used without any particular restriction, but fatty acid soaps, rosin acid soaps, etc. are common.

Typical examples of the aromatic vinyl compound include styrene, α-methylstyrene, vinyltoluene, tert-butylstyrene, and the like. Also, the general formula CH
Representative examples of the ethylenically unsaturated compound represented by t=CRX include acrylonitrile, methacrylonitrile, and methyl, ethyl, propyl, butyl esters of acrylic acid or methacrylic acid, with acrylonitrile and methacrylonitrile being particularly preferred. .

Even when graft polymerizing the above monomer (3), it is also possible to use a small amount of a crosslinking agent or a grafting agent.

The grafting ratio of the obtained graft copolymer resin (4) is preferably 5 to 150%, and the reduced viscosity of the free (co)polymer extracted from the graft copolymer resin (4) with acetone ( ηsp/c Nidimethylformamide (90.2% by weight, 25°C) is preferably in the range of 0.3 to 1. If the grafting ratio is less than 5%, the development of impact strength will be poor and the gloss of the molded product will be reduced. descend. Also,
If the grafting ratio exceeds 150%, processability (fluidity) and impact strength will decrease. ηsp/c of free (co)polymer
If it is less than 0.3, the impact strength decreases, and if it exceeds ■, the processability (fluidity) decreases.

The graft copolymer resin (4) thus obtained can be used as is, but a separately produced hard thermoplastic resin (5) is added to the total resin composition (total of (4) and (5)). It can also be used as a resin composition in which the proportion of composite rubber (2) is 5 to 80% by weight.

As the above-mentioned hard thermoplastic resin (5), any resin that is hard at room temperature can be used without particular restriction, but acrylonitrile-butadiene-styrene terpolymer (
ABS resin), acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), aromatic vinyl compound-acrylonitrile copolymer, aromatic vinyl compound-acrylonitrile-methyl methacrylate terpolymer, methyl methacrylate polymer, Styrene-acrylonitrile-N
-Phenylmaleimide terpolymer, α-methylstyrene-styrene-acrylonitrile-N-phenylmaleimide quaternary copolymer, α-methylstyrene-acrylonitrile-N-phenylmaleimide terpolymer, aromatic vinyl compound- Preferred examples include acrylonitrile-lower alkyl acrylate terpolymer, acrylonitrile-lower alkyl acrylate copolymer, polyvinyl chloride, and polycarbonate.

It is also possible to use the above hard resins in combination.

The thermoplastic resin composition of the present invention may optionally contain various coloring agents such as dyes and pigments, lubricants such as metal soaps, and stabilizers against light such as hindered amine compounds, benzotriazole compounds, and benzophenone compounds. In combination, a hindered phenol compound, thioether compound, or phosphite compound may be used alone or in combination as a stabilizer against heat, and an inorganic or organic granular, powder, or fibrous filler, a blowing agent, etc. You can add it.

In addition, this composition can be molded by various processing methods such as injection molding and extrusion molding, and can be used as various molded products with excellent impact resistance and weather resistance, and as a component of laminate structures, such as those exposed to sunlight. It can also be used as the outermost layer.

【Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In the examples, % and parts represent weight % and parts by weight, respectively.

Example 1 [Production of 1F composite rubber latex EPDM rubber latex (average particle size 0.5 μm, gel content 60%, use of ethylidene norbornene, iodine value 1
5) Charge 50 parts (as solid content) into a reaction vessel, add 1 part of disproportionated potassium rosin acid and 150 parts of ion-exchanged water, and after purging with nitrogen, raise the temperature inside the reaction vessel to 70°C. did. To this, add potassium persulfate (K) to 10 parts of ion-exchanged water.
Add a solution in which 0.12 parts of PS) were dissolved, and separately prepared 80 parts of butyl acrylate (BuA), 0.32 parts of allyl methacrylate (AMA), and 0.16 parts of ethylene glycol dimethacrylate (EDMA). The internal temperature stopped increasing as soon as the nitrogen-substituted monomer mixture was continuously added dropwise over 2 hours.
When the temperature was further raised to 80°C and stirring was continued for 1 hour, the polymerization rate was 9.
It reached 8.8% and a composite rubber latex was obtained. The degree of swelling of this composite rubber was 6.4, the gel content was 93.0%, and the particle size was 0.28 μm.

[11] Production of graft copolymer latex 30 parts (as solid content) of the composite rubber latex obtained in [I] was charged into a reaction vessel, diluted by adding 140 parts of ion-exchanged water, and the internal temperature of the reaction vessel was raised to 70%. The temperature was raised to ℃. After 1.35 parts of benzoyl peroxide (13PO) was dissolved in 70 parts of a separately prepared monomer mixture for graft polymerization consisting of acrylonitrile (AN)/styrene (ST) = 29/71, the mixture was purged with nitrogen. This monomer mixture was added to the reaction vessel at a rate of 15 parts/hour using a metering pump. After dropping all the monomer mixtures, the internal temperature was raised to 80°C and stirring was continued for 30 minutes to obtain a graft copolymer latex with a polymerization rate of 9.
It was 9%.

Part of the latex of the obtained graft copolymer was coagulated by adding dilute sulfuric acid, and the powder obtained by drying was extracted under refluxing methyl ethyl ketone to determine the reduced viscosity of the extracted resin (ηsp/c
) was measured at 25°C using dimethylformamide as a solvent and found to be 0.67.

[Salting out and pelletizing the m1 polymer. Aluminum chloride (AlCl2.6H,O) was added to the latex produced as above in an amount three times that of the entire latex.
It was poured into a 0.15% aqueous solution (90°C) with stirring and solidified.

After the addition of all the latex was completed, the temperature in the coagulation tank was raised to 93° C. and left as it was for 5 minutes. After cooling, it was dehydrated using a centrifugal dehydrator, washed, and dried. To 100 parts of the dry powder of this graft copolymer, 1 part of barium stearate, Antige W-300 (trade name, Kawaguchi Chemical Co., Ltd.)
Co., Ltd., phenolic antioxidant) 0.1 part, Tinuvin P (
Add 0.5 part of UV absorber (product name, Ciba Geigy) and mix at 20 (1 (lrpm) in a Henschel mixer.
After combining for 5 minutes, the mixture was pelletized using a 40 mmφ extruder at a cylinder temperature of 220° C. (Bellet A).

Example 2.3 In Example 1, the monomer to be grafted onto the composite rubber latex was changed from AN/ST to methyl methacrylate (M
The graft polymer was polymerized in exactly the same manner as in Example 1, except for changing to MA), and this graft polymer was salted out in the same manner as in Example 1, blended based on the following two formulations, and extruded. A square timber was obtained by the machine.

Compound A (square material A-1) Polyvinyl chloride (P, = 700) 100
1 part dibutyltin mercaptate 2 parts dibutyltin malate 2 parts dioctyl phthalate (OOP) Calcol #86 6 parts 0.8 parts Metablane P-551 (trade name, manufactured by Mitsubishi Rayon ■) 0
．． 5 parts Metapreny/P-700 (same as above) 0.5 parts Graft copolymer 10 parts Blend B (Square B
-1) Polyvinyl chloride (P, = 1100) 10
0 parts tribasic lead sulfate 2 parts dibasic lead stearate 0.5 parts lead stearate 1.2 parts calcium stearate 1.2 parts graft copolymer 10 parts Example 4 In Example 1, composite rubber latex The monomer to be grafted was changed from AN/ST to MMA/ST (=75
/25) was polymerized in exactly the same manner as in Example 1 to obtain a pellet (Bellet B).

Comparative Example 1 In Example 1, the manufacturing process of composite rubber latex of [■] was omitted, and a graft obtained by directly graft polymerizing 30 parts of EPDM latex (as solid content) by the method of [II] above. A pellet was obtained in exactly the same manner as in Example 1 except that the copolymer was used (Bellet C).

Comparative Example 2.3 In Examples 2 and 3, similar to Comparative Example 1, [II] composite rubber latex manufacturing process was omitted, and EP
Squares were prepared in exactly the same manner as in Examples 2 and 3, except that 30 parts of DM latex (as solid content) were used with the graft copolymer obtained by graft polymerization according to the method [II]. Bar A-2 and square bar A-3 were obtained.

Comparative Example 4 In Example 4, the graft copolymer obtained by graft polymerization by the method of [rl] above was directly added to 30 parts (as solid content) of EPDM latex by omitting the manufacturing process of composite rubber latex in [II]. A pellet was obtained in exactly the same manner as in Example 1 except that the polymer was used (Bellet D).

[Evaluation method] Berets A-D obtained in Example 1.4 and Comparative Example 1.4
A molded specimen was obtained using an injection molding machine (Model 5AV-30A screw type manufactured by Yamaguchi Seiki Co., Ltd.) under conditions of a cylinder temperature of 200°C and a mold temperature of 60°C. On the other hand, the square bars obtained in Example 2.3 and Comparative Example 2.3 (A-1 to B-
Regarding 2), a specimen was obtained by cutting this. Each evaluation was carried out by the method shown below, and the results are shown in Table 1.

(1) Weather resistance test Black panel 83℃, spray cycle 18 minutes/1 using weather meter WE-DCH model manufactured by Suga Test Instruments ■
Changes in gloss were measured under conditions of 20 minutes.

(2) Glossiness Manufactured by Suga Test Instruments ■, digital variable angle glossy needle (incident angle = 60°
).

(3) Izotsu impact strength (Iz) Measured according to ASTM D-256.

(4) Particle size of latex A calibration curve was created from the relationship between the particle size measured by electron microscopy and the absorbance at a wavelength of 700 nm of a diluted solution of the latex (0.15 g/7), and the absorbance of the latex was measured. It was determined from the calibration curve.

[Effect of the invention] The thermoplastic resin composition of the present invention includes: It has particularly excellent impact resistance.

Weatherability, Shockproof

Claims (1)

[Scope of Claims] 1) A crosslinking agent or a mixture of a crosslinking agent and a grafting agent in the presence of 5 to 90% by weight (as solid content) of the latex of the ethylene-propylene-nonconjugated diene copolymer rubber (1). Composite rubber (2) obtained by polymerizing 10 to 95% by weight of a monomer mainly composed of acrylic ester blended with
in the presence of 5 to 90 parts by weight (as solids) of a latex of general formula CH_2=CRX
(In the formula, R is H or CH_3, X is CN or CO
Represents OR^1. However, R^1 has 1 to 8 carbon atoms.
is an alkyl group. ) obtained by polymerizing 95 to 10 parts by weight of at least one monomer (3) selected from the group consisting of ethylenically unsaturated compounds represented by (100 parts by weight in total of (2) and (3)) Graft copolymer resin (4). 2) The graft copolymer resin (4) according to claim 1 and the hard thermoplastic resin (5) are combined into a resin composition ((4) and (5).
) in a total amount of composite rubber (2) in a proportion of 5 to 80% by weight.