JP4912594B2 - Thermoplastic resin composition and molded article - Google Patents

Description

  The present invention relates to a thermoplastic resin composition containing an aromatic polycarbonate and a molded article thereof.

A resin composition containing an aromatic polycarbonate is used in various fields as a molding material for various parts because of its excellent mechanical properties, heat resistance, and impact resistance.
Particularly for molding materials for automobile exteriors, PC / ABS resin compositions obtained by mixing acrylonitrile / butadiene / styrene (ABS) resin and aromatic polycarbonate (PC) are widely used. The molded product obtained from this PC / ABS resin composition has excellent impact resistance, and has improved moldability and impact strength thickness dependency which are disadvantages of aromatic polycarbonate. However, this PC / ABS resin composition and its molded product are easily deteriorated by heat and light, and are liable to cause a decrease in physical properties or discoloration due to retention during molding.

As countermeasures, acrylonitrile / butyl acrylate / styrene (ASA) resin, acrylonitrile / ethylene / propylene / non-conjugated diene / styrene (AES) resin, or the like may be used instead of the ABS resin.
As an AES resin, for example, Patent Document 1 proposes a resin containing a graft polymer obtained by emulsion graft polymerization of an aromatic vinyl monomer to an ethylene / propylene / non-conjugated diene copolymer rubber latex ( Patent Document 1). Patent Documents 2 and 3 disclose emulsion graft polymerization of an aromatic vinyl monomer and a vinyl cyanide monomer with a specific production method on an ethylene / propylene / non-conjugated diene copolymer rubber latex having a specific gel fraction. The thing containing the graft polymer obtained by this is proposed (refer patent document 2, 3).
JP-A 63-291913 JP 63-291194 A Japanese Unexamined Patent Publication No. 63-291944

Although the PC / AES resin composition containing AES resin and aromatic polycarbonate described in Patent Documents 1 to 3 has excellent weather resistance, impact resistance, particularly low temperature impact resistance, is insufficient.
An object of the present invention is to provide a thermoplastic resin composition and a molded article that solve the above-mentioned problems and are excellent in weather resistance and excellent in impact resistance, particularly low-temperature impact resistance.

The thermoplastic resin composition of the present invention contains an aromatic polycarbonate (A), an ethylene / propylene / non-conjugated diene copolymer and a low molecular weight modified α-olefin copolymer, and is measured by the following method. A monomer mixture containing 65 to 90% by mass of an aromatic vinyl monomer and 35 to 10% by mass of a vinyl cyanide monomer in a rubber polymer (B) having a degree of 15 to 37 % by mass. A graft polymer (D) obtained by graft polymerization of C), and a copolymer (E) obtained by copolymerizing an aromatic vinyl monomer and a vinyl cyanide monomer ( however, aromatic The total of the polycarbonate (A), the graft polymer (D) and the copolymer (E) is 100 parts by mass) . The rubber polymer (B) is composed of the ethylene / propylene / nonconjugated diene copolymer and the low molecular weight. Modified α-Olef The emissions copolymer melt-kneaded, and wherein the is obtained by adding to an aqueous medium containing an emulsifier.
[Method for measuring degree of crosslinking]
1 g of a dried product obtained by coagulating a rubber polymer latex, washing and drying with water is immersed in toluene at 125 ° C. for 40 hours, and then filtered and dried. Then, the degree of crosslinking (%) is determined by the formula: amount of dry substance after filtration and drying (g) / sample mass before immersion in toluene (g) × 100.
In the thermoplastic resin composition of the present invention, the graft polymer (D) is obtained by graft polymerizing 55 to 25% by mass of the monomer mixture (C) to 45 to 75% by mass of the rubbery polymer (B). It is preferable.
The molded article of the present invention is characterized by comprising the above-described thermoplastic resin composition.

  The thermoplastic resin composition and molded product thereof of the present invention are excellent in weather resistance and also in impact resistance, particularly in low temperature impact resistance.

<Aromatic polycarbonate (A)>
As the aromatic polycarbonate (A), those having a viscosity average molecular weight (Mv) of 16000 to 30000 are preferable. When the viscosity average molecular weight is less than 16000, impact resistance may be lowered, and when it exceeds 30000, moldability tends to be lowered.

<Rubber polymer (B)>
The rubbery polymer (B) contains an ethylene / propylene / non-conjugated diene copolymer (hereinafter abbreviated as “EPDM”) and a low molecular weight modified α-olefin copolymer. The rubber polymer (B) is usually used as an aqueous dispersion.

The rubbery polymer (B) has a crosslinking degree of 15 to 55% by mass. When the degree of crosslinking of the rubber polymer (B) is 15 to 55% by mass, the low temperature impact resistance, particularly the low temperature notched impact resistance can be increased. However, if the degree of crosslinking is less than 15% by mass or exceeds 55% by mass, the impact resistance is lowered.
Here, the degree of crosslinking was determined by coagulating a rubber polymer latex with dilute sulfuric acid, washing with water and drying, then collecting 1 g of the dried product and immersing it in 200 ml of 125 ° C. toluene for 40 hours. It is obtained by filtering through a mesh wire net, drying the residue, and measuring the mass of the dried product.
Degree of crosslinking (%) = Dry substance amount (g) / Sample mass (g) × 100

  In order to adjust the degree of crosslinking of the rubber polymer (B), a method of crosslinking the uncrosslinked rubber polymer is employed. As a method for crosslinking, 0.3 to 5 parts by mass of organic peroxide such as t-butyl-cumyl peroxide and divinylbenzene are used with respect to 100 parts by mass of the solid content of the uncrosslinked rubber polymer latex. A method of adding 0.1 to 5 parts by mass of the above polyfunctional compound and reacting at 60 to 140 ° C. for about 0.5 to 7 hours may be mentioned.

 The non-conjugated diene component in the EPDM contained in the rubbery polymer (B) is not particularly limited, but 1,4-hexadiene, 5-ethylidene-2-norbornene, 5-vinylnorbornene, dicyclopentadiene, and the like are preferable. .

  The rubbery polymer (B) may contain a rubber component other than EPDM. Examples of rubber components other than EPDM include polybutadiene, hydrogenated polybutadiene, polyisoprene, styrene-butadiene copolymer, styrene-isoprene copolymer, butadiene-acrylonitrile copolymer, ethylene-butene-1- (non- Conjugated diene) copolymer, isobutylene-isoprene copolymer, acrylic rubber, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, SEBS and other hydrogenated diene systems (block, random and homo ) (Co) polymer, polyurethane rubber, silicone rubber and the like.

The low molecular weight-modified α-olefin copolymer is one in which the α-olefin copolymer is modified with a compound having a functional group and the mass average molecular weight is 1000 to 5000. Examples thereof include modified polyethylene obtained by copolymerizing 99.8 to 80% by mass of an α-olefin and 0.2 to 20% by mass of an unsaturated carboxylic acid compound. Here, examples of the α-olefin include ethylene, and examples of the unsaturated carboxylic acid compound include acrylic acid, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, and maleic acid monoamide.
Since the low molecular weight modified α-olefin copolymer is contained in the rubbery polymer (B), the emulsion stability can be increased, and thus the production stability is increased.

  The content of the low molecular weight modified α-olefin copolymer in the rubber polymer (B) is preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of EPDM. If the content of the low molecular weight modified α-olefin copolymer is 0.1 parts by mass or more, emulsion graft polymerization can be performed more stably, but if it exceeds 30 parts by mass, the physical property balance of the obtained thermoplastic resin composition is lowered. Tend to.

  The rubbery polymer (B) preferably has an average particle size of 0.2 to 1 μm because it is excellent in the physical property balance of the resulting thermoplastic resin composition. When the average particle diameter is less than 0.2 μm, the impact resistance of the resulting thermoplastic resin composition may be lowered. When it exceeds 1 μm, the gloss tends to decrease and the surface appearance tends to deteriorate. is there.

The rubbery polymer (B) is subjected to emulsion graft polymerization in a latex state.
As a method for preparing a rubbery polymer latex, a predetermined amount of EPDM and a low molecular weight modified α-olefin copolymer is kneaded by a known melt kneading means, and sufficiently dispersed by applying a mechanical shearing force. The method of adding a thing to the aqueous medium containing an emulsifier is mentioned. According to this method, a stable rubber polymer latex can be obtained.
The melt kneading means in the latex preparation method is not particularly limited, but a kneader, a Banbury mixer, and a multi-screw extruder are preferable. Moreover, as an emulsifier, anionic surfactants, such as potassium oleate and disproportionated potassium rosinate, are used, for example. The addition amount of the emulsifier is preferably 1 to 10 parts by mass with respect to 100 parts by mass of EPDM. The emulsifier may be added by, for example, mixing oleic acid in advance with EPDM and a low molecular weight modified α-olefin copolymer, and adding potassium hydroxide aqueous solution thereto to form potassium oleate. .

<Monomer mixture (C)>
The monomer mixture (C) is a mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer as essential components and another vinyl monomer polymerizable with these as an optional component. .
Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, and the like.
Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile.
Examples of other vinyl monomers include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate and butyl acrylate, methyl methacrylate, ethyl methacrylate, propylene methacrylate and butyl methacrylate. Methacrylic acid alkyl ester and the like. Among these, butyl acrylate or methyl methacrylate is preferably used.
Other vinyl monomers include maleimide, N-methylmaleimide, N-butylmaleimide, N-phenylmaleimide, N- (2-methylphenyl) maleimide, N- (4-hydroxyphenyl) maleimide, N -N-substituted maleimide monomers such as cyclohexylmaleimide.

  Since the composition of the monomer mixture (C) is excellent in the physical property balance of the resulting thermoplastic resin composition, the aromatic vinyl monomer is 65 to 90% by mass, and the vinyl cyanide monomer is 35 to 35%. It is preferable that 10 mass% and another vinyl-type monomer are 0-20 mass%.

<Method for producing graft polymer (D)>
Examples of the method for producing the graft polymer (D) include a method in which the monomer mixture (C) is added to the latex of the rubber-like polymer (B) and heated to a predetermined polymerization temperature for emulsion graft polymerization. . In particular, the monomer mixture (C) may be continuously added to the latex of the rubbery polymer (B) over a period of 1 hour or more after mixing the redox initiator with the monomer mixture (C). preferable. When the addition time of the monomer mixture (C) is less than 1 hour, the latex stability may be lowered and the polymerization yield may be lowered.
You may add antioxidant to the graft polymer (D) after superposition | polymerization as needed.

  The redox initiator used here is preferably a combination of an oil-soluble organic peroxide and a ferrous sulfate-chelating agent-reducing agent. Examples of the oil-soluble organic peroxide include cumene hydroperoxide, diisopropylbenzene hydroperoxide, and tertiary butyl hydroperoxide. More preferred redox initiators include cumene hydroperoxide, ferrous sulfate, sodium pyrophosphate, and dextrose.

  In the graft polymer (D), 55 to 25% by mass of the monomer mixture (C) is polymerized to 45 to 75% by mass (as a solid content) of the rubber polymer (B) ((B) and (C) ) 100 mass%). When the rubber polymer (B) is less than 45% by mass (monomer mixture exceeds 55% by mass), the impact resistance is lowered, and the rubber polymer (B) exceeds 75% by mass (single amount). The impact resistance also decreases when the body mixture is less than 25% by weight.

  A graft polymer latex is obtained by the above-described method for producing a graft polymer. As a method for recovering the graft polymer (D) from the graft polymer latex, for example, a precipitant is added to the graft polymer latex, and after heating and stirring, the precipitant is separated, washed with water, dehydrated and dried. A precipitation method is employed. As the precipitation agent in the precipitation method, for example, an aqueous solution of sulfuric acid, acetic acid, calcium chloride, magnesium sulfate, or the like can be used alone or in combination.

<Copolymer (E)>
The copolymer (E) is a copolymer of an aromatic vinyl monomer and a vinyl cyanide monomer. Further, the copolymer (E) may be copolymerized with other vinyl monomers copolymerizable with the aromatic vinyl monomer and the vinyl cyanide monomer.
Specific examples of the aromatic vinyl monomer, the vinyl cyanide monomer, and the other vinyl monomers include those similar to the monomer mixture (C).
Although there is no restriction | limiting in particular in the composition of a copolymer (E), 65-90 mass% of aromatic vinyl monomers, 35-10 mass% of vinyl cyanide monomers, and a copolymer with these monomers What contains 0-20 mass% of possible monomers as a structural unit is preferable.

For the production of the copolymer (E), a polymerization method such as emulsion polymerization or suspension polymerization is employed. When the copolymer (E) is produced by emulsion polymerization, each monomer, an emulsifier, a polymerization initiator, and a chain transfer agent are charged into the reactor and polymerized by heating. From the obtained copolymer latex The copolymer (E) is recovered by a precipitation method.
Here, general emulsifiers for emulsion polymerization such as potassium rosinate and sodium alkylbenzenesulfonate can be used as the emulsifier. Moreover, organic and inorganic peroxide initiators can be used as the polymerization initiator, and mercaptans, α-methylstyrene dimers, terpenes, and the like can be used as the chain transfer agent. As the precipitation method, a method similar to that for recovering the graft polymer (D) from the graft polymer latex can be employed.

In the case of producing by suspension polymerization, each monomer, suspending agent, suspending aid, polymerization initiator and chain transfer agent are charged into the reactor and polymerized by heating to obtain a copolymer slurry. And the copolymer (E) is recovered.
Here, as the suspending agent, tricalcium phosphite, polyvinyl alcohol or the like can be used, and as the suspending aid, sodium alkylbenzene sulfonate or the like can be used. Further, organic peroxides can be used as the polymerization initiator, and mercaptans, α-methylstyrene dimer, terpenes, and the like can be used as the chain transfer agent.

<Thermoplastic resin composition>
Since the thermoplastic resin composition has a good balance of physical properties including low temperature impact resistance, the total amount of the aromatic polycarbonate (A), the graft polymer (D) and the copolymer (E) is 100 parts by mass. The content of the aromatic polycarbonate (A) described above is 50 to 70 parts by mass, the content of the graft polymer (D) is 10 to 23 parts by mass, and the content of the copolymer (E) is 40 to 7 parts by mass. It is preferable that When the content of the graft polymer (D) is less than 10 parts by mass, the impact resistance is lowered, and when the content of the graft polymer (D) exceeds 20 parts by mass, the physical property balance is deteriorated.

  The thermoplastic resin composition includes an aromatic polycarbonate (A), a graft polymer (D), a copolymer (E) and, if necessary, an antioxidant, a lubricant, a processing aid, a pigment, a filler, and the like. It is easily manufactured by mixing with an additive and pelletizing with, for example, an extruder, a Banbury mixer or a kneading roll.

  This thermoplastic resin composition not only has excellent low-temperature impact resistance, but also has high color developability and is suitable for coloring. When the thermoplastic resin composition is colored, for example, a colorant such as a color pigment, dye, carbon black, or titanium oxide is used as an additive.

<Molded product>
Next, the molded product of the present invention will be described. The molded article of the present invention is obtained by molding the above-described thermoplastic resin composition. Examples of the molding method include an injection molding method, a press molding method, an extrusion molding method, a vacuum molding method, and a blow molding method.
The molded article of the present invention is suitable for automotive exterior parts such as bumpers, door mirrors, rear spoilers, etc., but can also be applied to other uses.

  EXAMPLES Hereinafter, although a manufacture example, an Example, and a comparative example are given and this invention is demonstrated further more concretely, unless this summary is exceeded, this invention is not limited to a following example. In the following, “part” means “part by mass” and “%” means “mass%”.

"Production Example 1" Production of rubbery polymer (B-1)
100 parts of EPDM (TP3180 manufactured by Mitsui Chemicals), 9 parts of low molecular weight modified polyethylene (High Wax 2203A manufactured by Mitsui Chemicals), and 2.6 parts of potassium oleate were mixed. Next, the mixture was fed at a rate of 6 kg / hour from a hopper of a twin screw extruder (PCM-30 type, L / D = 40, manufactured by Ikekai Steel Co., Ltd.), and a potassium hydroxide 15% aqueous solution was fed at 110 g / hour While continuously supplying, the melt was kneaded at a heating temperature of 200 ° C. to extrude the melt. Subsequently, the melt was continuously supplied to a cooling single screw extruder attached to the tip of the extruder and cooled to 90 ° C. The taken-out solid was poured into warm water at 80 ° C. and continuously dispersed to obtain a rubber polymer latex having an average particle size of 0.35 μm.

0.5 parts of t-butyl-cumyl peroxide and 1.0 part of divinylbenzene are added to 100 parts of the solid content of the latex and reacted at 135 ° C. for 5 hours to give a rubbery polymer (A-1 ) Was prepared.
The degree of crosslinking of the rubber polymer (B-1) was measured and found to be 37%. The degree of crosslinking was determined by coagulating the rubber polymer latex with dilute sulfuric acid, washing with water and drying, collecting 1 g of this, immersing it in 200 ml of toluene for 40 hours, and then filtering with a 200 mesh wire mesh. The residue was dried and measured for its mass.

"Production Example 2"
A rubber polymer (B-2) was prepared in the same manner as in Production Example 1 except that the amount of t-butyl-cumyl peroxide added was 0.84 part. The degree of crosslinking of the rubber polymer (B-2) was 52%.
"Production Example 3"
A rubber polymer (B-3) was prepared in the same manner as in Production Example 1 except that the amount of t-butyl-cumyl peroxide added was 2.0 parts. The degree of crosslinking of the rubber polymer (B-3) was 87%.
"Production Example 4"
A rubber polymer (B-4) was prepared in the same manner as in Production Example 1 except that the amount of di-t-butyl-cumyl peroxide added was 0.2 parts. The degree of crosslinking of the rubber polymer (B-4) was 12%.
"Production Example 5"
A rubber polymer (B-5) was prepared in the same manner as in Production Example 1 except that the amount of di-t-butyl-cumyl peroxide added was 0.05 parts. The degree of crosslinking of the rubber polymer (B-5) was 2%.

“Production Example 6” Graft polymer production method (D-1)
In a stainless polymerization tank equipped with a stirrer, 180 parts of ion exchange water, 70 parts of rubbery polymer (B-1) as solids, 0.3 part of oleic acid, 0.006 part of ferrous sulfate, 0. 23 parts and 0.35 part of dextrose were charged, and the temperature was 80 ° C. Next, 7.5 parts of acrylonitrile, 22.5 parts of styrene, and 0.6 parts of cumene hydroperoxide were continuously added for 170 minutes, and emulsion graft polymerization was performed while keeping the polymerization temperature constant at 80 ° C. The monomer conversion after the polymerization was 95%.
After the polymerization, an antioxidant is added to the obtained graft polymer latex, solid content is precipitated with sulfuric acid, and after washing, dehydration and drying, the powdered graft polymer (D-1) is obtained. Obtained.

"Production Example 7"
A graft polymer (D-2) was obtained in the same manner as in Production Example 6 except that the rubber polymer (B-2) was used instead of the rubber polymer (B-1).
"Production Example 8"
A graft polymer (D-3) was obtained in the same manner as in Production Example 6 except that the rubber polymer (B-3) was used instead of the rubber polymer (B-1).
"Production Example 9"
A graft polymer (D-4) was obtained in the same manner as in Production Example 6 except that the rubber polymer (B-4) was used instead of the rubber polymer (B-1).
"Production Example 10"
A graft polymer (D-5) was obtained in the same manner as in Production Example 6 except that the rubber polymer (B-5) was used instead of the rubber polymer (B-1).
Table 1 shows the type and amount of the rubbery polymer and the amount of the monomer mixture in Production Examples 6 to 10.

“Production Example 11” Copolymer Production Method (E)
In a stainless steel polymerization reactor equipped with a stirrer purged with nitrogen, 120 parts of ion exchange water, 0.1 part of polyvinyl alcohol, 0.3 part of azobisisobutyronitrile, 23 parts of acrylonitrile, 77 parts of styrene, t-dodecyl mercaptan 0 .3 parts were charged. The reactor was heated to 50 ° C. for 5 hours, heated to 120 ° C., polymerized for 4 hours, and then extracted to obtain a copolymer (E). The monomer conversion in the polymerization was 98%, and the obtained copolymer (E) had a mass average molecular weight of 1.0 × 10 ⁵ .

  S-1000 manufactured by Mitsubishi Engineering Plastics Co., Ltd. was used as the aromatic polycarbonate (A).

(Example 1 , Reference Example 2 and Comparative Examples 1 to 3)
Each component obtained by the method described above was mixed in the formulation shown in Table 2, and the mixture was melt-kneaded with an extruder to obtain a thermoplastic resin composition.

The mechanical strength and the notched impact resistance of the obtained thermoplastic resin composition were evaluated as follows. The evaluation results are shown in Table 2.
Mechanical strength: Using Toshiba Machine's injection molding machine IS55FP-1.5A, a test piece was prepared according to ISO 3167, and the bending strength was measured according to the method of ISO 178.
Notched impact resistance: Using Toshiba Machine's injection molding machine IS55FP-1.5A, a test piece was prepared according to ISO 3167 and measured according to the method of ISO 179.

In Example 1 and Reference Example 2 satisfying the scope of claim 1 of the present application, both the impact resistance and the surface impact resistance were high even at −30 ° C. On the other hand, Comparative Example 1 in which the degree of crosslinking of the rubbery polymer exceeds 55% has low impact resistance with notches, and Comparative Examples 2 and 3 in which the degree of crosslinking of the rubbery polymer is less than 15% are also included. The sex was low.

Claims (3)

An aromatic polycarbonate (A);
A rubbery polymer (B) containing an ethylene / propylene / non-conjugated diene copolymer and a low molecular weight modified α-olefin copolymer and having a crosslinking degree of 15 to 37 % by mass measured by the following method, A graft polymer (D) formed by graft polymerization of a monomer mixture (C) containing 65 to 90% by mass of an aromatic vinyl monomer and 35 to 10% by mass of a vinyl cyanide monomer;
And a copolymer (E) obtained by copolymerizing an aromatic vinyl monomer and a vinyl cyanide monomer ( however, an aromatic polycarbonate (A), a graft polymer (D) and a copolymer ( total 100 parts by weight of E)),
The rubbery polymer (B) is prepared by adding a kneaded material prepared by melt-kneading the ethylene / propylene / non-conjugated diene copolymer and the low molecular weight modified α-olefin copolymer to an aqueous medium containing an emulsifier. And a thermoplastic resin composition obtained by crosslinking treatment .
[Method for measuring degree of crosslinking]
1 g of a dried product obtained by coagulating a rubber polymer latex, washing and drying with water is immersed in toluene at 125 ° C. for 40 hours, and then filtered and dried. Then, the degree of crosslinking (%) is determined by the formula: amount of dry substance after filtration and drying (g) / sample mass before immersion in toluene (g) × 100.   The thermoplastic resin composition according to claim 1, wherein the graft polymer (D) is obtained by graft polymerization of 55 to 25% by mass of the monomer mixture (C) to 45 to 75% by mass of the rubbery polymer (B).   A molded article comprising the thermoplastic resin composition according to claim 1.