JPS6243463B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polyester resin compositions. More specifically, the present invention relates to a polyester resin composition with little warpage and extremely high impact resistance. In recent years, engineering plastics have increasingly been used as an alternative to some mechanical structural materials. Engineering and materials share in total materials
As usage of plastics increases and experience accumulates, the advantages and disadvantages of each engineering plastic are becoming clearer.
Resin compositions reinforced with reinforcing materials are used as mechanical structural materials, and among them, polyalkylene terephthalate reinforced with reinforcing materials is in demand due to its good mechanical strength, heat resistance, and chemical resistance. is increasing. Glass fiber has traditionally been widely used as a reinforcing material for polyalkylene terephthalate. Such fibrous inorganic materials are useful because they improve the mechanical properties and heat distortion temperature of polyalkylene terephthalate, but because they have directionality, they cause so-called "warpage" when producing plate-shaped molded products. It has the disadvantage of causing On the other hand, many attempts have been made to improve the warping, and methods have been proposed such as using glass beads or milled fibers instead of glass fibers, or replacing glass with mica or talc as reinforcing materials.
These methods are certainly effective in reducing warpage, but on the other hand, mechanical properties may not be improved as much as when using glass fibers, or coloring may occur due to the reinforcing material, making it difficult to use. However, it has not been fully satisfied as a structural material. Therefore, it is desired to develop a polyester composition that has excellent mechanical properties and thermal properties, good color tone, and has little or no warpage. The present inventors conducted studies to obtain a polyester resin that satisfies these points, and found that a desired polyester composition can be obtained by modifying the matrix. That is, they have discovered that by melt-blending aromatic polyester with a modified ethylene polymer and a reinforcing material, warpage can be significantly reduced even when the reinforcing material is glass fiber. More surprisingly, the above compositions also show a significant improvement in impact resistance. That is, the gist of the present invention is that 5 to 5 parts by weight of glass fiber (B) is added to 100 parts by weight of thermoplastic aromatic polyester (A).
Obtained by graft polymerizing 125 parts by weight and 0.05 to 3% by weight of an α/β-unsaturated carboxylic acid or an acid derivative thereof to an ethylene polymer or a copolymer of ethylene and an α-olefin having 3 or more carbon atoms. Crystallinity 75% or less, melt index 0.01~50
A polyester resin composition is prepared by mixing 5 to 100 parts by weight of a modified ethylene polymer (C). The present invention will be described in detail below. As the thermoplastic aromatic polyester of component (A) used as one of the raw materials in the present invention, various well-known types can be mentioned. Specifically, at least one difunctional carboxylic acid such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, and ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene. Examples include thermoplastic polyesters obtained by polycondensation with at least one type of glycol such as glycol and decamethylene glycol. Among these, preferred are polytetramethylene terephthalate, polypropylene terephthalate, and polyethylene terephthalate, which have a fast crystallization rate.
Particularly preferred is polytetramethylene terephthalate. Of course, two or more of these thermoplastic aromatic polyesters may be used in combination. Intrinsic viscosity of thermoplastic aromatic polyester (30 using a mixed solvent of phenol/tetrachloroethane (weight ratio 1)
(measured in °C) usually ranges from 0.5 to 2.0. The glass fibers of component (B) used in the present invention are glass strands, rovings, milled fibers, etc. that are generally used for reinforced thermoplastic resins, and are subjected to conventional treatments such as silane treatment, borane treatment, or titanate treatment. It is better to use the same method. The amount of glass fiber used is 5 to 125 parts by weight per 100 parts by weight of the thermoplastic aromatic polyester (A). If the amount is less than 5 parts by weight, the effect of the present invention will not be sufficient, and if it exceeds 125 parts by weight, it will be difficult to mix uniformly and the moldability of the composition will deteriorate, which is not preferred. The modified ethylene polymer as component (C) used in the present invention has the following structure. That is, an α/β-unsaturated carboxylic acid or an acid derivative thereof is added to an ethylene polymer or a copolymer of ethylene and an α-olefin having 3 or more carbon atoms (hereinafter both are collectively referred to as unmodified ethylene polymer). Melt index (MI
) 0.01 to 50 modified ethylene polymer is used. As the unmodified ethylene polymer, a copolymer type is preferable, and as the α-olefin having 3 or more carbon atoms as a copolymerization component, propylene, 1-butene, 1-hexene, 1-decene, 4-methylbutene- Examples include 1,4-methylpentene-1. Among these, propylene and butene-1 are particularly preferred. The α/β-unsaturated carboxylic acids or acid derivatives thereof (hereinafter collectively referred to simply as α/β-unsaturated carboxylic acids) to be graft-polymerized to the unmodified ethylene polymer include acrylic acid, methacrylic acid, and ethacrylic acid. , maleic acid, fumaric acid, or esters, acid anhydrides, or imides of the aforementioned acids. Among these, maleic anhydride and maleic acid imide are particularly preferred. The amount to be graft polymerized must be within the above range, preferably 0.1
-1% by weight. Incidentally, graft polymerization here means that a part or all of the unmodified ethylene polymer is chemically bonded to a monomer or polymer of an α/β-unsaturated carboxylic acid or a derivative thereof. Such modified ethylene polymers are produced by adding α/β-unsaturated carboxylic acids to unmodified ethylene polymers having a crystallinity of 75% or less and a melt index of 0.01 to 50 in accordance with conventional methods. It can be easily produced by melt-kneading at ~300°C. A screw type extruder is often used for melt-kneading. Of course, in order to efficiently cause graft polymerization, α・α′-bis-t-butylperoxy-p
- An organic peroxide such as diisopropylbenzene may be used in an amount of 0.001 to 0.05% by weight based on the unmodified ethylene polymer. The amount of the modified ethylene polymer (C) used is 5 to 100 parts by weight, preferably 5 to 40 parts by weight, per 100 parts by weight of the thermoplastic aromatic polyester (A). If the amount is less than the above range, there will be little effect, and if it is more than the above range, the mechanical strength will be significantly reduced, which is inappropriate. The inorganic solids (excluding glass fibers) as component (D) that are optionally used in the present invention include powders that are normally used as fillers for resins or rubbers. More specifically, it includes fillers added to the resin for the purpose of increasing volume, adjusting viscosity, and modifying physical properties. Inorganic solids include, for example, granular or amorphous fillers such as calcium carbonate, titanium oxide, feldspathic minerals, clay, white carbon, carbon black, glass beads, etc.; plate-shaped fillers such as kaolin clay, talc, etc.; Examples include long columnar fillers such as calcium metasilicate; flaky fillers such as mica and graphite; and fibrous fillers such as asbestos and ceramic fiber. Particularly preferably granular, amorphous,
Examples include plate-like and long columnar fillers. The amount of the inorganic solid component (D) used in the present invention varies depending on the amount of glass fiber (B) used, but it is not more than 125 parts by weight based on 100 parts by weight of the aromatic polyester. , preferably 100 parts by weight or less, more preferably 75 parts by weight or less.
If it exceeds 125 parts by weight, it will be difficult to mix uniformly.
Moreover, the moldability of the composition is also reduced, which is not preferable. Mixing can be carried out by simultaneously premixing each component (A), (B), (C), and optionally (D), and melt-mixing using a conventional extruder or similar equipment. . However, it is possible to melt and mix both components (A) and (B) in advance, and then mix (C) and (D) in some cases, or to mix the molten mixture of (A) and (B) in a master batch. Mixing this with (A), (B), (C) and (D) gives better results. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In addition, in the following examples, the "amount of warpage" was measured as follows. The polyester compositions produced by the methods shown in Examples and Comparative Examples were chipped and molded using a 2.5-ounce injection molding machine at a molding temperature of 260°C when polytetramethyl terephthalate was used as a matrix and a molding pressure of 20 to 30 kg/cm ^{2 .} , holding pressure for 10 seconds, cooling for 30 seconds, and molding at a mold temperature of 80°C. The shape of the molded product is 3mm thick,
It consists of a 78mm diameter disc with 8 ribs 10mm wide and 15mm high, with a pin gate in the center of the disc.
The thickness of the disk is 3 mm in the 270° angle area centered on the pin gate, 2 mm in the 45° area, 4 mm in the remaining 45° area, and 2 mm in the 2 mm area and 4 mm in the remaining 45 degree area.
The regions are adjacent and the eight ribs are arranged on one side of the disk at about the same distance from the central pin gate and equally spaced from each other. Since the largest warpage appears in the parts of the molded product with the most significant thickness deviation (thicknesses of 4 mm and 2 mm), place the molded product on a flat surface so that the non-ribbed side of the disk is in contact with the flat surface. With three points of the 3mm thick part of the disk in contact with the plane,
The maximum gap between the disk and the plane (usually appearing at a 2 mm or 4 mm thick portion) was measured and determined as the amount of warpage. Crystallinity is X according to the description in Journal of Polymer Science Vol. (1955), pages 17-26.
Measured by line method. MI is ASTMD−123857T (190
(measured at °C). Izot impact strength was measured with a notch according to ASTM D256-56 A. "Parts" indicate "parts by weight." Reference Example 1 [Production of modified ethylene copolymer] 100 parts of ethylene-propylene copolymer with crystallinity of 20% and MI5.0, α・α′-bis-t-butylperoxy dissolved in a small amount of acetone. 0.025 parts of -P-diisopropylbenzene and 0.5 parts of maleic anhydride were blended in a Henschel mixer. This blend was extruded at 230° C. using an extruder with an inner diameter of 40 mm and L/D=28, and pelletized to obtain a modified ethylene polymer. After crushing a portion of the pellets, unreacted maleic anhydride was removed with acetone using a Soxhlet extractor for 12 hours.
Time extracted. After drying this material, press mold it.
When maleic anhydride was quantified using an infrared absorption spectrum, it was found that 0.36% by weight of maleic anhydride was graft polymerized. Further, the crystallinity was 20% and the MI was 3.5. Examples 1 to 3 and Comparative Examples 1 to 3 Intrinsic viscosity (measured at 30°C using a mixed solvent with a 1/1 weight ratio of phenol/tetrachloroethane)
20 parts of the above-mentioned modified ethylene polymer were blended with 80 parts of polytetramethylene terephthalate (referred to as P-1) of 1.1, and melt-mixed at a cylinder temperature of 240°C using an extruder with a diameter of 90 mm. The obtained polyester composition was chipped (this was
-2) Glass fibers (manufactured by Asahi Fiberglass Co., Ltd., 03MA416A) and/or inorganic solids were blended with the composition shown in Table 1, and the mixture was melt-mixed at a cylinder temperature of 250°C in an extruder with a diameter of 20 mm to form pellets. The amount of warpage and Izot impact strength of the obtained composition were measured. The results are shown in Table 1. 【table】

Claims (1)

[Scope of Claims] 1. 100 parts by weight of thermoplastic aromatic polyester (A), 5 to 125 parts by weight of glass fiber (B) and ethylene polymer or copolymerization of ethylene and α-olefin having 3 or more carbon atoms. A modified ethylene polymer (C) with a crystallinity of 75% or less and a melt index of 0.01 to 50 obtained by graft polymerizing 0.05 to 3% by weight of α/β-unsaturated carboxylic acid or its acid derivative to the polymer.
Polyester resin composition 2 formed by mixing 5 to 100 parts by weight of glass fiber (B) and modified ethylene polymer (C) to 100 parts by weight of thermoplastic aromatic polyester (A).
The composition according to claim 1, further comprising 125 parts by weight or less of an inorganic solid (D) other than component (B).