JPS61228036A - Glass fiber reinforced resin material - Google Patents

Abstract

PURPOSE:To obtain the title material giving a formed product having excellent strength at high temperature, strength in wet state, impact strength and flexural strength, smooth surface and excellent appearance, by adding glass fibers having specific average fiber diameter to a thermoplastic resin. CONSTITUTION:A thermoplastic resin is reinforced with glass fibers having an average fiber diameter of 4-9mu. Preferably, chopped strand produced by colleccting about 100-10,000 glass fibers and cutting to 3-8mm length is used in combination with a surface-treating agent, a lubricant, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a fiber-reinforced resin material containing glass fibers.

[Prior art] Glass fiber reinforced resin materials (hereinafter referred to as glass fiber reinforced resins) are widely used as structural members, mechanical parts, electrical parts, etc., and are superior to metals and ceramics in terms of productivity and specific strength. Although this is advantageous, various efforts have been made to further improve the strength.

[Problems to be Solved by the Present Invention] An object of the present invention is to improve the heat resistance strength, water resistance strength, impact resistance strength, etc. of glass fiber reinforced resin, thereby meeting the above-mentioned demands.

[Means for Solving the Problems] The inventors conducted various experiments and research on the fracture mechanism of glass fiber reinforced resin. As a result of observing the destruction process using a scanning electron microscope, the following facts were confirmed.

First, when a load is applied to the glass fiber reinforced resin, stress concentrates at the interface between the glass fibers and the matrix, particularly at the tips of the glass fibers, causing cracks as shown in the electron micrograph of FIG. When the external load is further increased, the cracks propagate to the sides of the fibers and further into the interior of the matrix toward adjacent glass fibers, promoting failure of the fiber interfaces. In this way, cracks propagate one after another, leading to destruction of the entire material. At this time, the glass fibers are hardly destroyed.

The present invention has been made based on this knowledge. Conventionally, glass fibers having an average diameter of about 13 μm have been used, but in the present invention, glass fibers having an average diameter of 4 μm to 9 μm are used. This made it possible to significantly improve heat resistance, water resistance, and impact resistance.

The reason for this is that when the glass fiber content is the same as before (generally 10% to 45% by weight), reducing the fiber diameter increases the number of fibers, which increases the interfacial area of the fibers and It is recognized that this is due to the fact that the stress transmission efficiency from the matrix to the fibers is increased through the fibers, and as a result, the stress sharing of the matrix is reduced. In addition, an increase in the number of fibers reduces the spacing between the fibers, and as a result, the excessive stress in the matrix generated at the fiber tip is shared by other fibers close to the fiber tip, reducing stress concentration at the fiber tip. It is recognized that this is because cracks are less likely to occur, and even if cracks do occur, the growth of cracks is slowed down due to the large number of fibers.

In the case of the present invention, if the diameter of the glass fiber is 4μ or less, the productivity of the fiber itself is poor, and if this is mixed with resin to make a glass fiber reinforced resin molded product, the fiber will be finely broken and the matrix reinforcement effect will be impaired. descend. Therefore, the strength of the glass fiber reinforced resin also decreases. Further, if the diameter of the glass fiber is 9 μm or more, stress concentration at the tip of the fiber increases, and the fiber itself acts like a foreign substance. Therefore, the strength of the glass fiber reinforced resin also decreases.

The material of the glass fiber used in the present invention is not particularly limited, and commonly used C glass, E glass, etc. can be used. The glass fibers are used in the form of so-called chopped strands, which are bundled into a bundle of about 100 to 100 fibers and cut into lengths of about 3 to 8 Iry1. Further, the glass fibers contain a sizing agent for focusing the monofilaments, a surface treatment agent for increasing the reactivity with the resin, a lubricant necessary for processing the fibers, and the like.

On the other hand, as the resin used in the present invention, thermoplastic resins such as polyamide, polyester, and polyacetal, so-called engineering plastics, are most preferably used, but the resin is not particularly limited thereto. For example, nylon 6, nylon 66, nylon 12, polybutylene ethylene leftate, polyacetal homopolymer, etc. may also be used.

When preparing the glass fiber-reinforced resin of the present invention as a molded product, for example, chopped strand-shaped glass fibers and pellet-shaped thermoplastic resin are mixed in a V-shaped blender and then melt-kneaded in an extruder. The pellets are then injection molded to form parts.

[Experiment example] Chopped strands 3 to 9 made of glass fibers bundled to a length of 5 mrn and nylon 66 pellets (Leona 13008>7ffy manufactured by Asahi Kasei Corporation) were premixed in a ■ type blender, and the mixture was mixed with a biaxial The pellets were melted and kneaded using an extruder. Tensile test specimens were molded by injection molding using the extruder. Glass fibers of various diameters were used. Strength tests were conducted on these test specimens. I did it.

Test conditions followed ASTM standards.

Figure 2 shows the results of the heat resistance strength test. Heat resistance strength was evaluated by tensile strength at each temperature in the high temperature range. The products of the present invention with an average fiber diameter of 7μ and 4μ) have an average fiber diameter of 1
It has superior heat resistance and strength compared to Tochichi's 3μ (conventional product). Note that when the average fiber diameter is reduced to 0.5 μm, the heat resistance strength decreases.

Figure 3 shows the results of the water resistance strength test. The strength was evaluated by immersing the test piece in pure water at 80°C. In terms of strength, the fibers with an average fiber diameter of 7μ are far superior to those with an average fiber diameter of 13μ.

FIG. 4 shows the results of impact resistance (Charpy impact value) Tetos. Impact resistance is best when the average fiber diameter is 4μ to 9μ.

Figure 5 shows the Tetos results of bending strength. The average fiber diameter is 4
It is known that the products of the present invention having a thickness of μ to 7μ have particularly excellent bending strength.

FIG. 6 shows the bending strength of a product of the present invention with an average fiber diameter of 7μ and a conventional product with an average fiber diameter of 13μ when the fiber content was changed. Regardless of the fiber content, the products of the present invention are 20 to 30% superior in strength to conventional products.

FIG. 7 shows the results of measuring the acoustic emission (AE) generated during the bending test of the test piece. In addition,
Acoustic emissions are elastic waves in the ultrasonic range that are generated from internal minute cranks caused by material deformation, and by measuring these elastic waves, it is possible to non-destructively analyze the progress of fracture inside the material. . As can be seen from the figure, the load at which acoustic emission occurs is higher in the product of the present invention with an average fiber diameter of 7μ compared to the conventional product with an average fiber diameter of 13μ, and the product of the present invention is less prone to internal cracks than the conventional product and is more reliable. expensive.

[Effects of the Invention] As explained above, the present invention has investigated the fracture mechanism of glass fiber reinforced resin, and by using fibers with an average diameter of 4 μm to 9 μm, it has particularly improved heat resistance strength, water resistance strength, impact resistance strength, and bending strength. A material with excellent strength can be obtained. In addition, according to the present invention, material strength equal to or higher than that of conventional products can be obtained even with a smaller amount of fiber content than conventional products, so the surface is smoother without deteriorating the strength compared to conventional products. A product with an excellent appearance can be obtained.

[Brief explanation of drawings]

Figure 1 is an electron micrograph showing the occurrence of cracks in glass fiber-reinforced thermoplastic resin materials, Figures 2, 3, and 4.
5, 6 and 7 are diagrams showing the results of strength tests on the products of the present invention, respectively. Figure 1 111111'' Figure 4 Flat S#i diameter ()Jm) Figure 5 Average MS width (μm) Procedural amendment c method) Patent dated July 16, 1985 Director General. ,,
71. Indication of the case 1985 Patent Application No. 69593 2. Name of the invention Glass fiber reinforced resin material 3. Person making the amendment Relationship to the case Patent applicant 41 Yokomichi, Nagakuku, Aza, Aichi-gun, Aichi Prefecture 1 (3)
60) Toyota Central Research Institute Co., Ltd. Representative Director Noboru Komatsu 4, Agent 4-7-23 Meieki, Nakamura-ku, Nagoya, Aichi 450 δ
, date of the amendment order June 10, 1985 7. In the statement of contents of the amendment, page 8, lines 2 to 3, the statement ``Figure 1 is an electron micrograph'' has been replaced with ``Figure 1. is an electron micrograph showing the appearance of cracks at the interface between glass fiber and resin matrix in a glass fiber-reinforced thermoplastic resin.

Claims (1)

[Claims] A glass fiber-reinforced resin material characterized in that the thermoplastic resin material is reinforced by containing glass fibers and has an average glass fiber diameter of 4 μ to 9 μ.