JPH10219026A - Glass fiber reinforced resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin molded article blended with glass fiber, which has a large warp and twist, and a great reduction in strength when blended with mica and glass flakes and reduced twist. A part of a glass fiber having a circular cross section to be mixed with a thermoplastic resin is replaced with a glass fiber having a flat cross section, thereby preventing a decrease in strength and reducing warpage and twist.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin reinforced resin composition, and more particularly to an injection molded article having improved strength and warpage.

[0002]

2. Description of the Related Art Glass fibers having a circular cross section are mixed in a thermoplastic resin to reinforce the resin and improve physical properties, and are widely used for producing various fiber-reinforced plastic molded products. However, the glass fiber has a longer length than the diameter and has anisotropy, so that a mixture of resin and glass fiber is pressed into the mold gate as in injection molding, and the fiber flows when flowing in a certain direction. The thermal expansion coefficient varies depending on the location, and appears as warpage and twist. In order to prevent this warping and twisting, glass flakes with little vertical and horizontal directions, mica, etc. are compounded.
Products containing glass flakes, mica and the like have a problem that the warpage and torsion decrease in proportion to the increase in the amount, but the mechanical strength decreases. Further, glass flakes are expensive, and there is a problem that a molded product using mica is colored in the color of mica.

[0003]

When glass flakes, mica powder and the like are blended, warpage and torsion of injection-molded products are reduced. However, in order to ensure the effect, if the blending amount is increased, the tensile strength and the like are increased. However, there is a problem that the mechanical strength of the material rapidly decreases. An object of the present invention is to provide a thermoplastic resin composition in which warpage and twist of an injection-molded article are reduced and strength is less reduced.

[0004]

Means for Solving the Problems The present inventors used a mixture of glass fibers having a flat cross section and glass fibers having a normal cross section to reduce warpage and torsion, and to reduce the machinedness of molded products. The present invention was completed by conducting various tests after discovering that there was little decrease in the mechanical strength.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to 40-98 parts by weight of a thermoplastic resin and 1-60% by weight of a short diameter (a longest linear distance perpendicular to a long diameter in a right-angle cross section of a fiber) relative to a resin composition ) Is 3-10 μm, the ratio of the major axis to the major axis = major axis / minor axis is 1.5-10, and the cut length is 2 mm-30 mm. 60% by weight of glass fiber chopped strands with a cut length of 2 mm-30 mm having a circular cross section of 2-19 μm are compounded. Desirable proportions of the two types of glass fibers are such that the ratio of flat glass fiber / normal glass fiber is 1 / 10-10 / 1, and the total amount is 2/10.
It is a thermoplastic resin molded product containing -66% by weight of glass fiber. In addition, if necessary, other inorganic fillers such as glass fiber powder, talc, charcoal, mica, and glass flakes, flame retardants, pigments, antistatic agents, etc. are usually compounded according to the use of the injection molded product. The material to be formed can be appropriately compounded according to the purpose of use of the molded article.

The thermoplastic resin used in the present invention is not particularly limited, and examples thereof include polycarbonate resin, acrylic resin, ABS resin, polyamide resin, saturated polyester resin, polyacetal resin, and polyphenylene. A sulfide resin or the like and various alloys of these resins, or a mixture of two or more of these resins can also be used.

The two types of glass fibers used in the present invention are produced by a known method for producing glass fibers, and a silane coupling agent and a titanium-based coupling agent are used to improve adhesion to a matrix resin and uniform dispersibility. At least one coupling agent such as a zirconia-based coupling agent.
It is bundled with a known sizing agent suitable for the compounding resin containing the type, antistatic agent, film forming agent, etc., and used in the form of chopped strands obtained by collecting and cutting the bundled glass fiber strands to a certain length. Is done. The cross section of the flat glass fiber used in the present invention is desirably a gourd type, a cocoon type, an oval type, an elliptical type, a rectangular type, or a similar product thereof. Further, as the flat fibers, those having a ratio of major axis / minor axis of 1.5 to 10 are used, and those having a ratio of 2.0 to 6 are more preferable. When the ratio of major axis to minor axis is 1.5 or less, the effect of flattening the cross section is small, and when the ratio is 10 or more, it is difficult to produce the glass fiber itself.

The total amount of these two types of glass fibers is preferably 2-66% by weight, and more preferably 10-55% by weight of the resin composition. The mixing ratio of these two types of glass fibers is by weight, and the ratio of flat glass fibers: normally glass fibers is in the range of 1: 10-10: 1, preferably 1: 2-10: 1. When the ratio is 1:10 or less, the effect of adding the flat glass fiber is small, and when the ratio is 10: 1 or more, there is no difference in the effect as compared with the case where the flat glass is blended alone.

The resin composition of the present invention has less warpage and a better surface condition than conventional glass fibers having a single circular or flat cross-sectional shape, but depending on the application. By blending other inorganic fillers, a molded product more suitable for the intended use can be obtained. Examples of such inorganic fillers include various powders such as silica, glass fine powder, kaolin, talc, titanium oxide, calcium carbonate, and alumina. Further, known antistatic agents, coloring agents, lubricants, release agents, nucleating agents,
Flame retardants, impact modifiers and the like can also be added.

These resins, glass fibers and the like are blended, heated, kneaded, extruded by an extruder, and the continuously extruded resin composition is cooled, cut and pelletized. The method of molding a pellet by an injection molding machine to obtain a predetermined molded product is a general method, but it is also possible to directly perform injection molding without pelletizing. Further, the glass fiber having a circular or flat cross section used in the present invention is a fiber having a general glass fiber composition such as E glass,
Any composition can be used as long as it can be made into glass fiber, and there is no particular limitation.

[0011]

The present invention will now be described by way of examples, which should not be construed as limiting the invention. The evaluation method is as follows. 1. Measurement of physical properties Tensile strength: Measured according to ASTM 0638. Strength after water absorption: A test piece used for tensile strength was placed in a pressure cooker, treated at 120 ° C. for 15 hours, and then subjected to the above tensile test. 2. Measurement of warpage A 120 mm square flat plate test piece (thickness: 3 mm, gate is one place at the center of the side) is molded, and the test piece is placed on a flat platen and the maximum distance from the platen is measured. The portion was measured as the amount of deformation.

Example 1-2 As shown in Table 1, a polyamide resin was used as the resin.
As a glass fiber, the ratio of the major axis to the minor axis is 2 and the 17
A glass fiber chopped strand (HIS870, manufactured by Nitto Boseki Co., Ltd.) having a diameter equivalent to μm (having a cross-sectional area equal to that of a glass fiber having a circular cross section of 17 μm) having a length of 3 mm and a normal circular cross section Glass fiber chopped strand (Nitto Boseki Co., Ltd .: CS
3PE-948, diameter 13 μm, length 3 mm). Each of these resins and glass fiber was 12 hours 12
The material was dried at 0 ° C. for 6 hours in a hot air circulating drier, and these materials were blended in the proportions shown in Table 1 and preliminarily mixed, and immediately extruded with a twin-screw vented extruder set at a cylinder temperature of 280 ° C. It was cut into pellets. After the obtained pellet was dried at 120 ° C. for 6 hours, a test sample was molded using an injection molding machine.

Comparative Example 1-6 As the matrix resin and the glass fiber, those used in Examples were used. The glass flakes had an average particle diameter of 100 μm, the average thickness was 4 μm, and the mica had an average particle diameter of 1 μm.
One having a thickness of 95 μm and an average aspect ratio of 75 was used. The proportions of these materials are shown in Table 1. Other molding conditions were the same as in the examples, and test samples were prepared using an injection molding machine.

[0014]

As is clear from the tables of Examples and Comparative Examples, when glass flakes and mica powder are blended to prevent warping of molded products, the tensile strength and water resistance are greatly reduced in any case. . However, according to the method of using the flat glass fiber of the present invention, there is an effect that the decrease in the tensile strength and the water resistance is small and the warpage is also small.

[0015]

[Table 1]

Claims (2)

[Claims] 1. A thermoplastic resin composition for injection molding containing at least 2-66% by weight of glass fiber, wherein the glass fiber has a diameter of 2-19 .mu.m and a circular cross-section. 1-60% by weight, minor axis 3-1
1 to 60% by weight of flat glass fiber having a flat cross section having a ratio of major axis / minor axis of 1.5 to 10 μm, and the weight ratio of the blended circular glass fiber to flat glass fiber is 1
0: 1-1: 10 is a thermoplastic resin composition. 2. A thermoplastic resin molded article obtained by molding the thermoplastic resin composition according to claim 1.