JP2008156507A - Thermoplastic composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thermoplastic resin excellent in the balance of heat resistance, appearance, low warpage, and scratch resistance. <P>SOLUTION: This thermoplastic resin composition comprises 20 to 60 pts.mass of a styrenic resin (A) having an unsaturated nitrile monomer content of 32 to 50 mass%, 20 to 60 pts.mass of an aromatic polyester (B) having an isothermal crystallization time of 20 to 100 sec from a melted state, and 20 to 60 pts.mass of a filler (C). <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a thermoplastic resin having an excellent balance of heat resistance, appearance, low warpage, and scratch resistance that could not be achieved by the prior art.

Aromatic polyesters represented by polyethylene terephthalate and polybutylene terephthalate are excellent in mechanical properties, chemical resistance, and electrical properties, and can be further enhanced in rigidity and heat resistance by reinforcing with fillers, such as automobiles, home appliances, and OA. Used in a wide range of fields. However, the filler-reinforced polyester has a problem in that the appearance of the product is impaired when the filler addition amount is large, and warping is easily generated when the filler addition amount is small, and the scratch resistance is low for use in appearance parts.
In order to improve the appearance and warpage of the molded product, blending polyethylene terephthalate with a composition comprising polybutylene terephthalate and styrene resin reinforced with filler (see, for example, Patent Document 1), or polytrimethylene reinforced with filler A composition comprising terephthalate and a thermoplastic composition (see, for example, Patent Document 2) has been reported.

It is known that the composition comprising these aromatic polyesters and styrene-based resins greatly changes in physical properties depending on their compatibility, viscosity, and volume ratio. In particular, the compatibility has a great influence on the change of the physical properties. However, the styrene-based resin in which the ratio of the unsaturated nitrile monomer having a relatively high compatibility with the aromatic polyester used in the composition with the conventional aromatic polyester is 20 to 30% by mass is a crystallinity of the polyester. There are problems such as lowering heat resistance and heat resistance. On the other hand, in order to improve the appearance, warpage, and scratch resistance, it is necessary to add a large amount of styrene resin, and it is difficult to maintain the balance of heat resistance, appearance, low warpage, and scratch resistance, A thermoplastic resin excellent in such a balance has been demanded.
Japanese Patent No. 3098308 JP 2003-20389 A

An object of the present invention is to provide an unprecedented balance of heat resistance, appearance, low warpage, and scratch resistance by using an aromatic polyester having a certain crystallization speed and a special styrene resin. The object is to obtain a plastic resin.

As a result of intensive studies to solve the above problems, the present inventors have found that a styrene resin containing 32 to 50% by mass of an unsaturated nitrile monomer in an aromatic polyester having an isothermal crystallization time from a molten state of 25 to 100 sec. By blending, it was ascertained that the appearance was excellent even with a high filler content, and the present invention was completed.
That is, the present invention is as follows.
1. 20-60 parts by mass of styrene-based resin (A) having an unsaturated nitrile monomer ratio of 32-50% by mass, aromatic polyester (B) 20-60 having an isothermal crystallization time from the molten state of 25-100 sec. A thermoplastic resin composition comprising mass parts and 20 to 60 mass parts of a filler (C).
2. 2. The thermoplastic resin composition as described in 1 above, wherein the aromatic polyester (B) is polytrimethylene terephthalate alone or a polyester mixture containing 50% by mass or more of polytrimethylene terephthalate.
3. 3. The thermoplastic resin composition as described in 1 or 2 above, wherein the styrene resin (A) is a styrene / acrylonitrile copolymer.

  The resin composition of the present invention is a thermoplastic resin composition excellent in appearance even with a high filler content, and the present invention provides a resin composition excellent in the balance of heat resistance, appearance, low warpage, and scratch resistance It became possible to do.

The present invention will be specifically described below.
The styrene resin (A) used in the present invention is a copolymer of at least an unsaturated nitrile monomer and an aromatic vinyl monomer, and other monomers that can be copolymerized as necessary. It can also be copolymerized. In general, these styrenic resins (A) are produced by emulsion polymerization, bulk polymerization or bulk / suspension polymerization, but are not limited thereto.
There is no restriction | limiting in particular in the unsaturated nitrile-type monomer used for a styrene-type resin (A), Although acrylonitrile, methacrylonitrile, an ethacrylonitrile, etc. are mentioned, Among these, acrylonitrile is preferable. These can be used alone or in combination of two or more.

The aromatic vinyl monomer is not particularly limited, and specific examples include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene and pt. -Butyl styrene etc. are mentioned, Among them, styrene and α-methyl styrene are preferably used. These can be used alone or in combination of two or more.
Examples of other copolymerizable monomers include acrylic acid and methacrylic acid ester compounds such as butyl acrylate, ethyl acrylate, and methyl methacrylate, N-phenylmaleimide, and maleic anhydride. These can be used alone or in combination of two or more.
Among these, styrene / acrylonitrile copolymer (hereinafter abbreviated as AS resin) containing 15% by mass or less of acrylonitrile as unsaturated nitrilyl, styrene as aromatic vinyl, and other copolymerizable monomers is preferable.

  In the styrene resin (A), the ratio of the unsaturated nitrile monomer in the acetone-soluble component is 32 to 50% by mass, and preferably 37 to 42% by mass. In order to improve scratch resistance, the content is 32% by mass or more, and is 50% by mass or less due to a decrease in thermal stability. Acetone-soluble components were added to 20 g of acetone to 1 g of a sample, shaken with a shaker until the soluble components were completely dissolved, centrifuged at 20000 rpm for 40 minutes, and only the soluble components were separated by filtration. For 4 hours to remove acetone, and further dried under reduced pressure at 100 ° C. for 1 hour. The ratio of unsaturated nitrile monomer can be determined by measuring the IR of the soluble component and using a calibration curve.

  The styrenic resin (A) may contain a rubbery polymer as long as the scratch resistance is not significantly impaired. Resins obtained by graft reaction of unsaturated nitrile monomers and aromatic vinyl monomers to rubbery polymers, and resins obtained by copolymerizing other copolymerizable monomers are also included. As the unsaturated nitrile monomer, aromatic vinyl monomer, and other copolymerizable monomers used, monomers similar to those shown above can be used.

  Although there is no restriction | limiting in particular in the rubber-like polymer used for styrene resin (A), Diene rubber, acrylic rubber, ethylene rubber, etc. can be used. Specific examples of these rubber-like polymers include polybutadiene, styrene-butadiene copolymer, block copolymer of styrene-butadiene, acrylonitrile-butadiene copolymer, butyl acrylate-butadiene copolymer, polyisoprene, butadiene- Methyl methacrylate copolymer, butyl acrylate-methyl methacrylate copolymer, butadiene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-isoprene copolymer And ethylene-methyl acrylate copolymer. Of these rubber-like polymers, acrylic rubber is preferably used.

The mass average particle diameter of the rubbery polymer is preferably 0.1 to 0.5 μm. The mass average particle diameter is preferably 0.1 μm or more from the viewpoint of the impact resistance improving effect, and 0.5 μm or less is preferable because it causes a decrease in the appearance of the molded product. The amount of the rubber-like polymer is preferably 15% by mass or less, more preferably 10% by mass or less, because it does not cause a decrease in scratch resistance.
Styrene / acrylonitrile / butadiene copolymer (hereinafter abbreviated as ABS resin) obtained by grafting acrylonitrile as an unsaturated nitrile monomer and styrene as an aromatic vinyl monomer onto a diene rubber, or an acrylic rubber. A resin obtained by grafting acrylonitrile as a saturated nitrile monomer and styrene as an aromatic vinyl monomer is preferably used.

As the aromatic polyester (B) itself used in the present invention, known ones can be used. Polyesters can be produced in a known manner by reaction of terephthalic acid, its esters or other ester-forming derivatives with 1,4-butanediol, 1,3-propanediol or 1,2-ethanediol. it can.
The aromatic polyester (B) may contain other copolymer components. Examples of such copolymer components include 1,2-butanediol, 1,3-butanediol, neopentyl glycol, 1,6-hexamethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, Examples thereof include ester-forming monomers such as ethylene oxide adducts of bisphenol-A, isophthalic acid, succinic acid, adipic acid, sebacic acid, dodecanedioic acid, fumaric acid, maleic acid, and 1,4-cyclohexanedicarboxylic acid. The copolymerization amount in the case of copolymerization is not particularly limited as long as it does not impair the object of the present invention, but it is usually preferably 30 mol% or less of the acid component or 30 mol% or less of the glycol component.

  The crystallization speed of the aromatic polyester is required to be from 25 to 100 seconds, preferably from 25 to 70 seconds, more preferably from 30 to 60 seconds, from the melted state at 270 ° C. In order to improve an external appearance, it is 25 sec or more, and it is 100 sec or less from the fall of a moldability. The isothermal crystallization time can be measured by a differential scanning calorimeter (DSC) by the following method. Using a differential scanning calorimeter, 5 mg of the sample is heated and dissolved from 30 ° C. to 270 ° C. at a heating rate of 100 ° C./min. After holding for 3 minutes, it is rapidly cooled to 140 ° C. at a set temperature drop rate of 500 ° C./min, and the isothermal crystallization time is measured. Here, the isothermal crystallization time is defined as the time from the holding at 270 ° C. for 3 minutes until the crystallization peak at 140 ° C. appears. Therefore, it can be determined that the shorter the isothermal crystallization time, the faster the crystallization.

  Moreover, isothermal crystallization time can be controlled by using other aromatic polyesters together. For example, when polybutylene terephthalate (hereinafter abbreviated as PBT) having a high crystallization rate is used, it is preferably used in combination with polyethylene terephthalate (hereinafter abbreviated as PET) having a low crystallization rate. However, when used in combination, transesterification proceeds and the crystallinity may decrease. Therefore, when polytrimethylene terephthalate (hereinafter abbreviated as PTT) having a moderately high crystallization rate is used alone or in combination with other aromatic polyesters, it is more preferable to use PTT as a main component, and to improve the appearance, scratch resistance, and low warpage. A high-hardness thermoplastic resin composition having excellent properties can be obtained.

A crystal nucleating agent may be added for the purpose of increasing the crystallization rate. As such a crystal nucleating agent, a known compound generally used as a crystal nucleating agent for an aromatic polyester resin is used. For example, talc, mica, boron nitride, kaolin, silica, clay, metal oxide, inorganic carboxylate, inorganic sulfonate, organic carboxylate, organic sulfonate, organic carboxylic ester salt, carbonate, α- An ionic copolymer composed of an olefin and an α, β-unsaturated carboxylate is preferably used. Among these, fatty acid metal salts represented by the following general formula (1) are more preferably used.
CH ₃ (CH ₂ ) _n COO (M) (1)
(Where n ≧ 0, M = Na, Ca, Li)

Among the fatty acid metal salts, higher fatty acid Na salts, higher fatty acid Ca salts, and higher fatty acid Li salts are more preferable. These crystal nucleating agents may be used alone or a mixture thereof.
The addition amount of the crystal nucleating agent is not particularly limited as long as the isothermal crystallization time of the aromatic polyester is within the scope of the present invention, and is appropriately selected according to the type, combination, performance, etc. of the crystal nucleating agent to be used.

  Specific examples of the filler (C) used in the present invention include glass fiber, carbon fiber, metal fiber, aramid fiber, potassium titanate whisker, aluminum borate whisker, wollastonite, talc, tankal, kaolin and mica. , Glass flakes, glass beads, titanium oxide, aluminum oxide and the like, and fibrous fillers are preferred. Among them, chopped strand type glass fibers are preferably used. Among these, for example, some talc, kaolin, mica, glass fiber, and the like have a property of acting as a crystal nucleating agent depending on the type used. Further, these fillers are particularly preferably surface-treated. The surface treatment is performed using a coupling agent or a film forming agent, and examples of the coupling agent include an epoxy coupling agent, a silane coupling agent, and a titanium coupling agent. In particular, when a fibrous filler is blended, the average fiber length, average fiber diameter, and aspect ratio of the fiber are not particularly limited, but the average fiber length is preferably 50 μm or more in view of mechanical characteristics and fatigue characteristics, and is 100 μm. More preferably, it is more preferably 150 μm or more. The average fiber diameter is preferably 5 μm or more, and the aspect ratio is preferably 10 or more.

  The resin composition of the present invention is a resin comprising 100 parts by mass in total of 20 to 60 parts by mass of a styrene resin (A), 20 to 60 parts by mass of an aromatic polyester (B) and 20 to 60 parts by mass of a filler (C). It is a composition. Styrenic resin (A) is 20-60 mass parts, Preferably it is 25-45 mass parts. The amount is 20 parts by mass or more for improving scratch resistance and low warpage, and 60 parts by mass or less for reducing heat resistance. The aromatic polyester (B) is 20 to 60 parts by mass, and preferably 25 to 50 parts by mass in order to obtain a resin composition having an excellent balance of heat resistance, low warpage and scratch resistance. A filler (C) is 20-60 mass parts, Preferably it is 25-35 mass parts. It is 20 parts by mass or more in order to improve the scratch resistance, and it is 60 parts by mass or less in order to cause a decrease in moldability and appearance.

The styrene resin (A) and the aromatic polyester (B) used in the present invention desirably have a difference in melt viscosity at the kneading temperature between them. MFR at 240 ° C. and a load of 5 kg is expressed as MFR-A and MFR. When represented by -A, it is desirable that the following condition is satisfied.
3 ≦ MFR-B / MFR-A ≦ 10
When the ratio of MFR-A and MFR-B is smaller than 3, the heat resistance is deteriorated. When the ratio of MFR-A and MFR-B exceeds 10, the compatibilization of the styrene resin (A) and the aromatic polyester (B) does not proceed, so that the moldability is poor and the physical properties are remarkably lowered. In order for the molded article obtained by the composition of the present invention to have more excellent heat resistance, the styrenic resin (A) in the resin composition is dispersed in the aromatic polyester (B) as the continuous phase. It is preferably present as a co-continuous phase.

  Furthermore, the thermoplastic resin composition of the present invention can be blended with various additives generally used for thermoplastic resin compositions for the purpose of improving other properties. Examples of such additives include halogen-containing compounds such as halogenated polycarbonate oligomers (for example, polycarbonate oligomers produced using brominated bisphenol A as a raw material) for the purpose of improving flame retardancy; halogenated epoxy compounds; And phosphorus-nitrogen compounds such as phosphonic acid amides; flame retardant aids (for example, antimony trioxide) and the like. Other phosphite, hindered phenol, benzotriazole, benzophenone, benzoate and cyanoacrylate UV absorbers and antioxidants, higher fatty acids, acid esters and acid amides, and higher alcohol and other lubricants Plasticizers, montanic acid and salts thereof, esters thereof, half esters thereof, release agents such as stearyl alcohol, stellar amide and ethylene wax, anti-coloring agents such as phosphites and hypophosphites, nucleating agents, amines An additive such as an antistatic agent such as a sulfonic acid type, a sulfonic acid type or a polyether type, or a colorant such as a pigment or dye may be contained.

  The thermoplastic resin composition of the present invention can be obtained by blending, mixing, and kneading the thermoplastic resin components at an appropriate ratio. Examples of equipment used for mixing various components include a Henschel mixer, a ribbon blender, and a drum tumbler. Examples of the apparatus used for kneading include a single-screw extruder, a twin-screw extruder, a continuous kneader with a twin-screw rotor, a multi-screw extruder, an open roller, and a Banbury mixer. it can.

  The thermoplastic resin composition of the present invention can be molded by a known method. Although it is molded by a molding method such as injection molding, extrusion molding, hollow molding, compression molding, transfer molding, calendar molding, etc., it is particularly preferably used for injection molding. Injection molding includes application techniques such as insert molding, gas assist injection molding, and injection compression molding, and is preferably used.

The scratch resistance of the molded product formed by molding the resin composition of the present invention is preferably 2H or more with the pencil scratch value (JIS K5600) used for the surface hardness test of the coating film as an index. 2H indicates that the surface of the molded product has a hardness that does not leave a scratch even when it is rubbed with a pencil having a hardness of 2H. When used for external members in a wide range of fields such as automobiles, home appliances and OA, there is a problem that scratches are generated and design properties are deteriorated, so that a surface hardness of 2H or more is desired. Also, if the surface hardness is 2H or higher, secondary treatment such as painting and hard coating becomes unnecessary, and benefits such as shortening the production cycle and reducing the environmental impact by reducing VOC are born.
The thermoplastic resin composition of the present invention has an excellent balance of heat resistance, appearance, scratch resistance, and low warpage, so that it has been difficult to develop by conventional techniques in a wide range of fields such as automobile parts, home appliances, and OA. Can be made possible.

The following examples and comparative examples are for more specifically explaining the present invention, and are not limited to the following examples. In addition, the used high-hardness thermoplastic resin composition and its compounding agent are as follows.
1. Raw materials used in Examples and Comparative Examples <Styrene resin (A)>
(A-1) AS resin comprising 40% by mass of acrylonitrile and 60% by mass of styrene and having a number average molecular weight of 57000 (manufactured by Asahi Kasei Chemicals Corporation)
(A-2) AS resin comprising 20% by mass of acrylonitrile and 80% by mass of styrene and having a number average molecular weight of 71000 (manufactured by Asahi Kasei Chemicals Corporation)
(A-3) ASA resin consisting of 50% by mass of acrylic rubber having a mass average particle size of 0.3 μm, 15% by mass of acrylonitrile, 35% by mass of styrene (A-4) 34% by mass of acrylonitrile, 66% by mass of styrene, AS resin having a number average molecular weight of 6700 (manufactured by Asahi Kasei Chemicals Corporation)
(A-5) AS resin comprising 30% by mass of acrylonitrile and 70% by mass of styrene and having a number average molecular weight of 5500 (manufactured by Asahi Kasei Chemicals Corporation)

<Aromatic polyester (B)>
(B-1) PBT having an isothermal crystallization time of 20 sec: GENERAX 2002 (manufactured by Polyplastics Co., Ltd.)
(B-2) Isothermal crystallization time is 50 sec and number average molecular weight is 9800 PTT: CP-502901 (manufactured by Shell)
(B-3) PET: NEH-2050 (manufactured by Unitika Ltd.)

<Filler (C)>
(C-1) Glass fiber (hereinafter abbreviated as GF) having an average fiber diameter of 10 μm surface-treated with an epoxy coupling agent: FT792 (manufactured by Owens Corning Japan)
(C-2) Wollastonite: NYGLOS8 (manufactured by Hayashi Kasei Co., Ltd.) having an average fiber diameter of 8 μm surface-treated with an epoxy coupling agent

2. Preparation and evaluation method of molded product Evaluation and various measurements in Examples and Comparative Examples are as follows.
The molded product was prepared using an injection molding machine. Each test piece was created and evaluated at a cylinder set temperature of 250 ° C. and a mold temperature of 95 ° C. using a J-100EPI injection molding machine manufactured by Nippon Steel Works and an SG100 injection molding machine manufactured by Sumitomo Heavy Industries.
[Deflection temperature under load (HDT)]
The deflection temperature under load at 1.8 MPa was measured according to ISO-75-1 and 2.
Unit: ° C.
[Pencil hardness]
This was performed according to JIS K5600.
[Waring]
A flat plate of 100 mm × 100 mm × 2 mm was formed with an injection molding machine, one corner was pressed, and the height at which the corner on the diagonal line was lifted was defined as the amount of warpage. Unit: mm.
[appearance]
A flat plate of 100 mm × 100 mm × 2 mm was formed with an injection molding machine, and the surface appearance was measured for Gs60 ° C. according to JISK7150 using a digital variable angle gloss type manufactured by Suga Test Instruments. When the measured value was 80 or more, ◎, when it was 60 to 80, ◯, and when it was less than 60, ×.

[Examples 1-5, Comparative Examples 1-8]
About each said component, (A) component and (B) component are dry-blended by the mixing | blending ratio shown by Table 1, and 240 using a PCM45 twin screw extruder (L / D = 28.9) made by Ikegai Co., Ltd. Melt kneading was performed at 0 ° C. The filler (C) was added from the side feeder.
In addition, the pellets obtained were obtained by using a J-100EPI injection molding machine manufactured by Nippon Steel Works, an ISO dumbbell test piece, a 100 mm × 100 mm × 2 mm flat plate using a SG100 injection molding machine manufactured by Sumitomo Heavy Industries, Ltd., a cylinder set temperature of 250 ° C., a mold It created and evaluated on the conditions of temperature 95 degreeC (metal mold | die surface temperature 98 degree | times). The evaluation results are shown in Table 1.
The isothermal crystallization time of the mixture of PBT and PET used in Example 1 was 30 seconds, and the isothermal crystallization time of the mixture of PBT and PET used in Comparative Example 6 was 28 seconds. The amount of the saturated nitrile monomer is 38.3% by mass, and the amount of the unsaturated nitrile monomer of the styrene resin used in Comparative Example 6 is 22.3% by mass.

[Example 6, Comparative Example 9]
It implemented like Example 2 except the ratio of the unsaturated nitrile monomer in a styrene-type resin (A) differing. The evaluation results are shown in Table 2.

Since the resin composition of the present invention has an excellent balance of heat resistance, appearance, scratch resistance, and low warpage, it has been difficult to develop in a wide range of fields such as automobile parts, home appliances, and OA by conventional techniques. Can be made possible.

Claims (3)

  20-60 parts by mass of styrene-based resin (A) having an unsaturated nitrile monomer ratio of 32-50% by mass, aromatic polyester (B) 20-60 having an isothermal crystallization time from the molten state of 25-100 sec. A thermoplastic resin composition comprising mass parts and 20 to 60 mass parts of a filler (C).   2. The thermoplastic resin composition according to claim 1, wherein the aromatic polyester (B) is polytrimethylene terephthalate alone or a polyester mixture containing 50% by mass or more of polytrimethylene terephthalate.   The thermoplastic resin composition according to claim 1 or 2, wherein the styrene resin (A) is a styrene / acrylonitrile copolymer.