JP4567965B2 - Resin composition - Google Patents

Description

  The present invention relates to a resin composition comprising a styrene resin and a polyester resin, which can solve the problem of brittleness, which is a problem when using a styrene resin that is a general-purpose resin.

  Polystyrene (PS) is often used for containers, housings, cases, covers and the like because of its excellent transparency, dimensional stability, hardness and the like. On the other hand, it is inferior in impact resistance, and rubber-modified impact-resistant polystyrene (HIPS) polymerized by adding a rubber component to improve this is widely known (Non-patent Document 1, etc.). However, the impact-resistant polystyrene to which the rubber component is added tends to cause cracks in the surface impact test, and is not sufficient as impact resistance. In addition, there is a drawback that the surface gloss is deteriorated by adding a rubber component.

  On the other hand, as the same styrenic resin, a resin obtained by copolymerizing an acrylonitrile component such as acrylonitrile-styrene copolymer (AS), acrylonitrile, polybutadiene-styrene copolymer (ABS), etc., has impact resistance and surface gloss. It is well known that

  Improve impact resistance and surface gloss by mixing styrene resins (AS, ABS, etc.) with an acrylonitrile component to improve surface impact strength and surface gloss, which are insufficient in PS or HIPS. However, in reality, the compatibility of the acrylonitrile component is poor, and the expected impact resistance and glossiness are not necessarily obtained, and it cannot be said that it is a practical molding material.

Published by Ichiro Sumoto “Styrol-based resin”, Nikkan Kogyo Shimbun, January 31, 1970

  An object of the present invention is to provide a resin composition that can improve the brittleness and appearance deterioration particularly when two or more types of styrenic resins are mixed and can be used favorably as various molded articles.

  As a result of intensive studies to solve the above problems, the present inventors have found that a resin composition in which a specific polyester resin is mixed with a styrene resin in a specific range solves the above problems, and has reached the present invention. did.

That is, the gist of the present invention is as follows.
(1) Resin composition comprising 70 to 99% by mass of a styrene-based resin (A) and 30 to 1% by mass of a polyester resin (B) having a glass transition temperature (Tg) of 0 ° C. or lower and a melting point (Tm) of 130 ° C. or lower . The styrene resin (A) is a mixture of two or more styrene resins, (a1) one or two resins selected from polystyrene and impact-resistant polystyrene, and (a2) acrylonitrile / styrene. A resin composition comprising one or two kinds of resins selected from a copolymer and an acrylonitrile / butadiene / styrene copolymer .
( 2 ) The resin composition according to ( 1 ), wherein the mass ratio of (a1) and (a2) is in the range of (a1) / (a2) = 95/5 to 5/95.
( 3 ) The resin composition according to ( 1 ), wherein the polyester resin (B) is at least one selected from the group consisting of polybutylene succinate, polybutylene succinate adipate, and polybutylene terephthalate adipate. object.

  According to the present invention, the impact strength of the styrenic resin is improved by blending a polyester resin having specific thermal characteristics. In particular, when used in a system in which a styrene resin having an acrylonitrile component is mixed with a polystyrene resin or a modified styrene resin, the effect of improving the compatibility is exhibited, and a resin molded product having excellent surface impact strength and appearance is obtained. And can be widely used as parts of electronic / electrical equipment, automobiles and the like.

  Hereinafter, the present invention will be described in detail.

The resin composition of the present invention needs a styrene-based resin (A) 70 to 99 wt%, that Do from the 30-1% by weight polyester resin (B) is not more than Tg of 0 ° C. or less and Tm130 ℃. When the blending amount of ( B) exceeds 50% by mass, not only the brittleness improving effect is saturated but also the adverse effect that the cooling time becomes too long at the time of injection molding appears. Moreover, the improvement effect of a brittleness is not fully exhibited as the compounding quantity of (B) is less than 1 mass%.

  The styrene resin used in the present invention is a styrene obtained by polymerizing one or more selected from styrene monomers and, if necessary, other vinyl monomers copolymerizable with these and rubbery polymers. Resin. Although content of the styrene component in resin is not specifically limited, Generally it is 40 mass% or more.

  Examples of the styrene monomer used in the styrene resin component include styrene, α-methyl styrene, o-methyl styrene, p-methyl styrene, vinyl xylene, ethyl styrene, dimethyl styrene, p-tert-butyl styrene, vinyl. Styrene derivatives such as naphthalene, methoxystyrene, monobromostyrene, dibromostyrene, fluorostyrene, tribromostyrene and the like, with styrene being particularly preferred. Furthermore, these can be used alone or in combination of two or more.

  Other vinyl monomers copolymerizable with the styrenic monomer include vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, aryl esters of acrylic acid such as phenyl acrylate and benzyl acrylate, methyl acrylate, and ethyl acrylate. Alkyl esters of acrylic acid such as propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, cyclohexyl acrylate, dodecyl acrylate, aryl methacrylates such as phenyl methacrylate, benzyl methacrylate, methyl methacrylate, ethyl Methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate Maleic monomers such as acrylate, alkyl methacrylates such as 2-ethylhexyl methacrylate, octyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, etc., epoxy group-containing methacrylates such as glycidyl methacrylate, maleimide, N-methylmaleimide, N-phenylmaleimide, etc. Body, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, phthalic acid, itaconic acid and other α, β-unsaturated carboxylic acids and their anhydrides.

  Examples of the rubbery polymer copolymerizable with the styrenic monomer include polybutadiene, polyisoprene, random copolymer and block copolymer of styrene / butadiene, acrylonitrile / butadiene copolymer, alkyl acrylate ester or methacrylic ester. Copolymers of acid alkyl esters and butadiene, diene copolymers such as butadiene / isoprene copolymers, ethylene / propylene random copolymers and block copolymers, ethylene / butene random copolymers and block copolymers Copolymers of ethylene and α-olefin, etc., ethylene / methacrylate copolymers, copolymers of ethylene and unsaturated carboxylic esters such as ethylene / butyl acrylate copolymers, ethylene / vinyl acetate copolymers, etc. Of ethylene and aliphatic vinyl , Ethylene / propylene / non-conjugated diene terpolymer such as ethylene / propylene / hexadiene copolymer, acrylic rubber such as polybutyl acrylate, and polyorganosiloxane rubber component and polyalkyl (meth) acrylate rubber component are separated Examples thereof include a composite rubber (hereinafter referred to as IPN type rubber) having a structure entangled with each other so as not to be able to do so.

  Examples of the styrene resin include polystyrene, styrene / butadiene / styrene copolymer (SBS), hydrogenated styrene / butadiene / styrene copolymer (hydrogenated SBS), hydrogenated styrene / isoprene / styrene copolymer (SEPS). ), High impact polystyrene (HIPS), acrylonitrile / styrene copolymer (AS resin), acrylonitrile / butadiene / styrene copolymer (ABS resin), methyl methacrylate / butadiene / styrene copolymer (MBS resin), methyl methacrylate・ Acrylonitrile / butadiene / styrene copolymer (MABS resin), acrylonitrile / acrylic rubber / styrene copolymer (AAS resin), acrylonitrile / ethylene propylene rubber / styrene copolymer (AES resin) and styrene / IP Resin type rubber copolymer, and the like.

  Moreover, the alloy thing of said styrene resin and other resin can also be mentioned. For example, ABS / PC (polycarbonate), ABS / PET (polyethylene terephthalate), ABS / PPE (polyphenylene ether), ABS / PBT (polybutylene terephthalate), ABS / PA (polyamide), HIPS / PPE, PS (polystyrene) / PPE, HIPS / polyolefin and the like can be mentioned.

  Among these, the combination of at least one of PS resin and HIPS resin (a1) and at least one of AS resin and ABS resin (a2) can greatly improve the surface impact strength and surface appearance. Can be suitably used because it is easily exhibited. The mixing ratio of (a1) and (a2) is preferably in the range of (a1) / (a2) = 95/5 to 5/95, particularly preferably in the range of 90/10 to 10/90.

  Tg of the polyester resin (B) in the resin composition of the present invention is required to be 0 ° C. or lower, and is preferably −20 ° C. or lower. If Tg exceeds 0 ° C., the impact resistance improving effect may be inferior. Further, there is no particular lower limit of Tg, but Tg of a general polyester resin is −45 ° C. or higher.

  Moreover, Tm of polyester resin (B) needs 130 degrees C or less, a preferable minimum is 60 degreeC, and a more preferable range is 70-115 degreeC. If Tm is less than 60 ° C., it is not preferable because it may stick to the mold during molding and impair the releasability. On the other hand, if Tm exceeds 130 ° C., the flexibility of the polyester resin itself is impaired, and the impact resistance improving effect becomes poor.

  Examples of the polyester resin (B) having the above thermal characteristics include aliphatic polyesters composed of aliphatic diols, aliphatic dicarboxylic acids or aliphatic oxycarboxylic acids, copolymers or mixtures thereof, and partially aromatics. It can be appropriately selected from copolymerized polyesters containing a group component.

  Examples of the aliphatic diol constituting the polyester resin (B) include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, decamethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol and the like. It is done. Examples of the dicarboxylic acid include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanoic acid, succinic anhydride, and adipic anhydride. Examples of the aliphatic oxycarboxylic acid include D-lactic acid, L-lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, and 2-hydroxycaproic acid.

  Examples of the aromatic component that can be copolymerized with the polyester resin (B) include terephthalic acid, isophthalic acid, bisphenol A, an ethylene oxide adduct of bisphenol A, and p-oxybenzoic acid.

  Furthermore, a carbonate component may be copolymerized with the polyester resin (B).

  Specific examples of the polyester resin (B) include polybutylene succinate, polybutylene succinate adipate, polybutylene succinate terephthalate, polyethylene succinate, polybutylene succinate carbonate, and polybutylene terephthalate adipate. In particular, polybutylene succinate, polybutylene succinate adipate, and polybutylene terephthalate adipate are preferable, and polybutylene succinate is most preferable. Moreover, what copolymerized lactic acid can also be used conveniently. These are all known as polyester resins having biodegradability.

  As the above-mentioned polyester resin, a commercially available product can be suitably used. For example, “GS Pla AZ-71TN” manufactured by Mitsubishi Chemical Corporation as polybutylene succinate, and Showa Polymer Co., Ltd. as “polybutylene succinate adipate” Examples of “Bionole 3003” and polybutylene terephthalate adipate include “ECOFLEX F BX7011” manufactured by BASF.

  Biodegradable polyester resins are not necessarily produced from plant-derived raw materials, except that polylactic acid is industrially produced from lactic acid components derived from plants such as corn. However, polybutylene succinate and the like are said to be capable of converting raw materials into plant-derived materials in the near future, and if a resin in which raw material conversion is achieved in this way is used, the resin composition of the present invention will be It contributes to the saving of oil resources and becomes environmentally friendly.

  The polyester resin (B) in the present invention can contain a carbodiimide compound as a hydrolysis inhibitor. The blending amount is not particularly limited, but is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the polyester resin from the viewpoint of hydrolysis resistance effect, and 10 parts by mass from the viewpoint of molding processability and physical property maintenance. The following is preferable. Examples of the carbodiimide compound include compounds having at least one carbodiimide group in the molecule, and may be aliphatic, alicyclic, or aromatic. For example, poly (4,4′-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly (m-phenylenecarbodiimide), poly (tolylcarbodiimide), poly (diisopropylphenylenecarbodiimide), poly (methyl-diisopropylphenylenecarbodiimide) , Poly (triisopropylphenylenecarbodiimide) and the like, and these can be used alone or in combination of two or more.

  In the present invention, the means for mixing the styrenic resin (A) and the polyester resin (B) is not particularly limited, and for example, it can be melt-kneaded using a general extruder. In order to improve the kneading state, it is preferable to use a twin screw extruder. The kneading temperature is preferably in the range of 140 ° C to 300 ° C, more preferably in the range of 180 to 250 ° C. The kneading time is preferably 20 seconds to 30 minutes. When the kneading temperature is less than 140 ° C. or when the kneading time is less than 20 seconds, the kneading is insufficient, and when the temperature exceeds 300 ° C. or the kneading time exceeds 30 minutes, the resin is decomposed and the physical properties are increased. It may cause a decrease or deterioration of color tone.

  As long as the characteristics of the resin composition of the present invention are not significantly impaired, pigments, heat stabilizers, antioxidants, weathering agents, flame retardants, plasticizers, lubricants, mold release agents, antistatic agents, glass fibers, inorganic You can pass on fillers. Examples of the heat stabilizer include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, and alkali metal halides. Inorganic fillers include talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, zinc oxide, zeolite, Examples include antimony trioxide, hydrotalcite, metal fibers, metal whiskers, ceramic whiskers, potassium titanate, boron nitride, galafite, and carbon fibers. In addition, the method of mixing these with the resin composition of the present invention is not particularly limited, a method of adding at the time of mixing the styrene resin and the polyester resin, a method of further melt-mixing to the resin composition after mixing of both resins, Examples thereof include a method of adding at the time of polymerization of either or both of a styrene resin and a polyester resin, or a method of adding them to either or both of the resins in advance before mixing the both resins.

  The thermoplastic resin composition of the present invention can be formed into various molded products by molding methods such as injection molding, blow molding, extrusion molding, inflation molding, and vacuum molding, pressure molding, and vacuum / pressure molding after sheet processing. . In particular, it is preferable to adopt an injection molding method, and in addition to a general injection molding method, gas injection molding, injection press molding, or the like can be employed. There are no particular restrictions on the resin temperature, mold temperature, injection pressure, and injection speed at the time of injection molding, but a mold temperature of 30 to 50 ° C., particularly about 40 ° C., is preferable because the molding cycle time can be shortened.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples. The measuring method used for evaluation of the resin composition of an Example and a comparative example is as follows.
(1) Measurement of glass transition temperature (Tg) and melting point (Tm) Using a DSC (DSC22 manufactured by Seiko Denshi Kogyo Co., Ltd.), the glass transition temperature (Tg) and the melting point (Tm) were measured at a heating rate of 10 ° C./min in a nitrogen atmosphere.
(2) Tensile strength Measured according to ASTM D-638. If this value is 25 MPa or more, it has practicality.
(3) Flexural modulus Measured according to ASTM D-790. If this value is 1.5 MPa or more, it has practicality.
(4) Surface impact strength Impact strength was evaluated by dropping a weight from a predetermined height onto a 50 × 90 × 2 mm plate with a DuPont impact tester. The surface impact strength was quantified by calculating the maximum applied energy (J) at which the molded product did not crack under the condition of a combination of a predetermined height and a weight load.
G = (maximum height at which the test piece does not crack) x (gravity acceleration) x (weight load)
(5) Surface impact evaluation In a DuPont impact tester, 1 kg of weight was dropped from a height of 50 cm onto a 50 x 90 x 2 mm plate, and "○" was not broken, and a crack occurred Is “△”, and the broken one is “×”. If this evaluation is ○, the surface impact strength is practically sufficient.
(6) Surface glossiness Glossiness at 20 ° incidence was measured with a gloss meter GM-3G manufactured by Murakami Color Research Laboratory Co., Ltd. using a plate for measuring surface impact strength. If this value is 40 or more, it is desirable practically.

Moreover, the various raw materials used for the Example and the comparative example are as follows.
1. Styrene resin (1) Impact polystyrene (HIPS): “576H” manufactured by BASF Japan
(2) Polystyrene (PS): “NF20” manufactured by Idemitsu Petrochemical Co., Ltd.
(3) Acrylonitrile-butadiene-styrene copolymer (ABS): “GP-35” manufactured by BASF Japan
(4) Acrylonitrile / styrene copolymer (AS): “100PC” manufactured by Nippon A & L Co., Ltd.
2. Polyester resin (1) Polybutylene succinate (PBS): “AZ-71TN” manufactured by Mitsubishi Chemical Corporation. In this case, a small amount of polylactic acid component is copolymerized. The resin has a Tg of −32 ° C. and a Tm of 110 ° C.
(2) Polybutylene succinate adipate (PBSA): “Bionore 3003” manufactured by Showa Polymer Co., Ltd. The resin has a Tg of −45 ° C. and a Tm of 95 ° C.
(3) Polybutylene terephthalate adipate (PBTA): “Ecoflex F BX7011” manufactured by BASF. This resin has a Tg of −30 ° C. and a Tm of 110 ° C.
(4) Polylactic acid (PLA): “TE-4000” manufactured by Unitika Ltd. The resin has a Tg of 58 ° C. and a Tm of 168 ° C.

Example 1
Using a twin-screw extruder (TEM 37BS type manufactured by Toshiba Machine Co., Ltd.), 95 parts by mass of HIPS / ABS = 50% by mass / 50% by mass and 5 parts by mass of PBS were supplied from the root supply port of the extruder. At this time, the barrel was 210 ° C., the screw rotation speed was 180 rpm, and the discharge was 20 kg / h. This pellet was vacuum-dried at 80 ° C. for 6 hours, and various test pieces were prepared and evaluated under the molding conditions described in Table 1 using an IS-100E injection molding machine manufactured by Toshiba Machine Co., Ltd.

Examples 2-7 and Comparative Examples 1-4
As shown in Table 1, resin composition pellets were obtained in the same manner as in Example 1 except that the blending amount of each component was changed, and this was injection molded under the conditions described in Table 1, and various evaluations were performed.

  The evaluation results of Examples 1 to 7 and Comparative Examples 1 to 4 are collectively shown in Table 1.

In each of Examples 1 to 7, a resin composition having an excellent balance of physical properties of tensile strength, flexural rigidity, and surface impact strength and excellent surface gloss was obtained. In particular, both the surface impact strength and the surface glossiness are improved. When Examples 1 to 3 are compared with Comparative Examples 1 and 2, the effect of the present invention is clear. In Comparative Example 3, the compounding amount of the polyester resin was used in a large amount exceeding the range of the present invention, so that the cycle time was long during the injection molding, resulting in a deterioration in productivity. Since Comparative Example 4 used polylactic acid having Tg and Tm out of the range, both surface impact strength and surface glossiness were inferior.

Claims (3)

Styrene-based resin (A) and 70 to 99 wt%, a glass transition temperature (Tg) 0 ° C. or less and the melting point (Tm) 130 ° C. or less of the polyester resin (B) a resin composition comprising a 30-1% by weight The styrene resin (A) is a mixture of two or more styrene resins, (a1) one or two resins selected from polystyrene and impact-resistant polystyrene, and (a2) an acrylonitrile / styrene copolymer. A resin composition comprising one or two kinds of resins selected from acrylonitrile / butadiene / styrene copolymers . The resin composition according to claim 1, wherein the mass ratio of (a1) to (a2) is in the range of (a1) / (a2) = 95/5 to 5/95. 2. The resin composition according to claim 1, wherein the polyester resin (B) is at least one selected from the group consisting of polybutylene succinate, polybutylene succinate adipate, and polybutylene terephthalate adipate.