JPS6142614B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing FRP by a spray-up method. The spray-up method, in which cut glass fiber bundles (abbreviated as CS) are sprayed onto the mold surface together with liquid thermosetting resin to form an uncured fiber-reinforced resin layer and harden the resin, is used for ships, bathtubs, and septic tanks. It is widely used in the production of etc. It is strongly desired that the CS used in the spray-up method have the following properties. (1) The various strengths of the resulting FRP, such as impact and tensile strength, must exceed specified standard values. (2) The resin retention capacity is sufficiently large. If the holding capacity is small, the resin content in the FRP cannot be sufficiently increased, and the resin will flow down the mold until it hardens, making it impossible to obtain a uniform FRP. (3) Shapeability is good. Mold attachment refers to the fact that the CS sprayed onto the mold surface is embedded in the resin and blends along the mold surface. If the mold attachment is poor, the tip of the CS will protrude from the resin layer. For this reason, the surface of FRP becomes rough, and CS in the initially formed layer tends to be blown away when spraying is repeated. When a glass fiber bundle is impregnated with liquid resin, the resin gets between the individual fibers that make up the glass fiber bundle, forms a thin layer of a predetermined thickness on the surface of each fiber, and is held by the fibers. . This thickness is determined by the properties (viscosity, interfacial tension, etc.) of the resin and glass fiber. Therefore, the amount of resin held by the glass fiber bundle is
It is thought that it is proportional to the surface area of the glass fiber.
Therefore, when the weight per unit length of the glass fiber bundle is constant, a glass fiber bundle made by bundling a large number of glass fibers with a small diameter has a larger resin retention amount (holding capacity). Further, when the thickness (weight per unit length) of the glass fiber bundle is constant, the smaller the thickness (diameter) of the individual glass fibers constituting the fiber bundle, the greater the flexibility of the fiber bundle. Therefore, it is thought that the smaller the diameter of the glass fiber, the better the shapeability. For this reason, comparatively thin glass fiber bundles with a diameter of about 10 μm have traditionally been used exclusively for spray-up;
As FRPs have become larger, there has been a strong demand for further improvements in the above performance. In the process of conducting various studies to further improve the performance of glass fiber bundles for spray-up use and to meet the above requirements, the present inventor discovered that an aqueous sizing agent containing a vinyl acetate resin emulsion as a main component was used as a film forming agent. 12~14μ as glass fiber
It has been found that, contrary to conventional wisdom, using glass fibers with a diameter of 10 μm is superior in terms of the amount of unsaturated polyester resin retained and moldability. Although it is not clear why such a result was obtained, it is thought to be approximately as follows. When a glass fiber bundle bundled with a vinyl acetate-based sizing agent is impregnated with liquid unsaturated polyester resin (hereinafter simply referred to as resin), the resin penetrates between the glass fibers. The vinyl acetate-based sizing agent is dissolved by the styrene contained in the resin, and the distance between the fibers gradually widens, allowing the resin to penetrate into the fiber bundle. Considering the case where the resin penetrates to the center of the fiber bundle and reaches a state of equilibrium, using 10μ fibers is better than using 12-14μ fibers. big. However, when using thicker fibers,
The gaps between the fibers are also large, and therefore the resin penetration rate per unit time is also large. Therefore, under the working conditions of industrial spray-up, when glass fibers with a diameter of 12 to 14 μm are used, the amount of resin retained is greater, and the sizing agent is quickly dissolved and the fiber bundle is opened. Therefore, it is thought that flexibility will be greater and moldability will be better. The thickness of the glass fiber is 15μ.
In the above case, it was not possible to obtain the above-mentioned good results. When the diameter of the glass fiber is 15μ or more, it is thought that the effect of decreasing the surface area and decreasing flexibility due to the increase in the diameter outweighs the effect of increasing the penetration speed of the resin. Next, the present invention will be explained in more detail. Glass fibers are produced by drawing molten glass flowing out from a number of small holes provided in the bushing. The diameter of the glass fiber is determined by the size of the pores, the drawing speed, etc. In the present invention, these conditions are determined experimentally to set the diameter to 12 to 14 microns, and the glass fibers are bundled by adding a binding agent containing a vinyl acetate resin emulsion as a film forming agent. The number of focused lines is set to 100 to 150, and the diameter (μ) ² × number of focused lines is determined to be in the range of 14.400 to 24.000. Below this range, the stiffness of the fiber bundle will be low and workability will be poor; above this range, the amount of resin retained will be insufficient. Vinyl acetate-based resins include vinyl acetate homopolymer, vinyl acetate,
Epoxy copolymers, vinyl acetate/acrylic copolymers, vinyl acetate/ethylene copolymers, etc. can be suitably used. As the vinyl acetate resin, those having a degree of polymerization of 400 to 2.000, preferably 500 to 1000, and a particle size of 0.1 to 2.0μ, preferably 0.2 to 0.5μ can be suitably used. As the sizing agent, it is appropriate to use an emulsion containing about 7 to 10% vinyl acetate resin as a solid content, and usually a lubricant and a coupling agent are used in addition to this. The amount of sizing agent to be added to the above-mentioned glass fibers is suitably about 0.7 to 2.0 wt% in terms of solid content, and can be added using a known sizing agent adding device. The above-mentioned glass fiber bundle is cut into lengths of 20 to 60 mm and sprayed onto the mold surface together with unsaturated polyester resin. It is appropriate that the amount of resin is 200 to 300 parts by weight per 100 parts by weight of the cut glass fiber bundle, and as is clear from the following examples, when the method of the present invention is used, the molding is better than that of the conventional method. Good adhesion and less significant tension than conventional ones,
Although the bending strength slightly decreases, the specified standard value is fully satisfied, and the impact strength, which is the most important for large spray-up products such as bathtubs, increases, making it possible to obtain a product that is superior in strength in a comprehensive comparison. . Next, examples of the present invention will be shown. Example: 100 glass fibers with a diameter of 13 μm were mixed with vinyl acetate homopolymer emulsion (degree of polymerization: 800) as a solid content of 7.
Glass fibers bundled by adding 1.0% by weight of a sizing agent as a solid content to the glass fibers, including 0.4% by weight of stearic acid/tetraethylenebentamine condensate (lubricant) and 0.1% by weight of a silane coupling agent. The bundle was cut to a length of 2.5 cm, and the cut fiber bundle and unsaturated polyester resin were repeatedly sprayed on the mold surface 5 times to form a resin layer containing 900 gr of fiber bundle and 2000 gr of resin per m ² and harden the resin. At least I manufactured a septic tank. A comparison under the same conditions with a glass fiber bundle produced in the same manner using 200 glass fibers with a diameter of 10 μm is as follows. 【table】

Claims (1)

[Claims] 1 Glass fibers with a diameter of 12 to 14μ are added with a sizing agent containing a vinyl acetate resin emulsion as a film forming agent, and 100 to 150 fibers are bundled, and the diameter (μ) is ² ×
A method for producing FRP, which comprises spraying cut glass fiber bundles having a bundle number in the range of 14,400 to 24,000 together with a liquid unsaturated polyester resin onto a mold surface and curing the resin.