JPH04290730A - Molding method for fiber reinforced synthetic resin composite - Google Patents

Abstract

PURPOSE:To enhance the adhesion of a core material with a fiber reinforced synthetic resin layer by a method wherein a thermosetting resin cured at relatively low temp. is supplied to the surface of the core material while the core- material is transferred in one direction and a reinforcing fiber impregnated with a thermosetting resin cured at relatively high temp. is supplied to the outer periphery thereof to perform pultrusion. CONSTITUTION:At first, a core material 1 is continuously transferred in a molding direction to be guided into a liquid tank 2 and the surface of the core material 1 is coated with an unsaturated polyester resin solution 3 cured at a relatively low temp. Glass rovings 5, 5 are delivered to be guided into a liquid tank 7 to be impregnated with an unsaturated polyester resin solution 6 cured at a relatively high temp. and guided to the outer periphery surface of the core material 1 by an arranging apparatus 8 and continuous mats 9, 9 are delivered to be superposed on the glass rovings 5, 5 while arranged in the same way by the arranging apparatus 8.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a fiber-reinforced synthetic resin composite comprising a core layer and a fiber-reinforced synthetic resin layer surrounding the core layer.

0002

[Prior Art] Conventionally, when a molded body is formed by a pultrusion method, there is a large difference in strength between the direction of pultrusion and the direction perpendicular to this, which limits the applications of the molded body. A molding method is known in which this drawback is solved by forming a composite body consisting of a fiber-reinforced synthetic resin layer formed as an outer layer, and using an isotropic body as the core material. According to this method, not only the directionality of strength is improved, but also the cross-sectional shape can be set arbitrarily by combining various types of core material, outer layer resin, outer layer fiber, etc., and the thickness of each layer. Coupled with the characteristics of the pultrusion method, it is possible to obtain desired strength, weight, and other physical properties, making it an excellent technology in that it is easy to obtain products with various properties depending on the application. It is.

However, the amount of heat required to harden the reinforcing fibers in the molding passage within the mold depends solely on heat transfer from the mold. Therefore, when looking at the temperature distribution of the molding material in the heat-curing section of the mold, the temperature is highest in the part in contact with the mold, gradually decreases as it goes inside (in the thickness direction), and the highest in the part in contact with the core material. This results in a temperature distribution with different heights.

[0004] Therefore, the curing phenomenon of resin in reinforcing fibers is as follows:
Curing progresses from the part in contact with the mold, and the part in contact with the core material is the slowest to cure. Due to the uneven curing speed of the resin in this outer layer part, the hardening occurs at the interface between the core material and the fiber-reinforced synthetic resin layer. Poor resin impregnation occurs due to curing shrinkage, resulting in the formation of voids, cavities, etc., resulting in poor adhesion between the core material layer and the fiber-reinforced synthetic resin layer, resulting in a decrease in strength. , In order to sufficiently harden the part in contact with the core material,
When trying to maintain the molding speed as low as possible, the thicker the fiber-reinforced synthetic resin layer becomes, the lower the molding speed becomes, resulting in the problem that the expected production speed cannot be obtained.

[0005] In order to solve this problem, various studies have been carried out in the past, one of which is the Japanese Patent Application Laid-open No. 63-3.
Publication No. 5332 describes a method for pultrusion molding of a composite body having a structure in which a metal material is used as a core material and a fiber-reinforced synthetic resin layer is formed around the core material. According to this method, two molds are arranged in the molding direction, and a core material made of a metal material is fed together with reinforcing fibers impregnated with a thermosetting resin.
The reinforcing fibers are heated by induction heating using high frequency waves in the mold that they pass through first, and then the reinforcing fibers are heated and hardened by the heat transfer from the mold that they pass through later, so the reinforcing fibers impregnated with thermosetting resin However, the temperature difference between the surface in contact with the metal core material and the surface in contact with the inner wall surface of the mold can be made to be almost non-existent, so that the curing speed of the thermosetting resin can be made uniform and there are no defects. This technology is attracting attention because it can prevent uniformly caused quality deterioration and production speed reduction.

[0006]

[Problem to be solved by the present invention] However, since the above-mentioned conventional technology uses electromagnetic induction as a heating method, there is a restriction that the core material is limited to metal, and it cannot be used for materials other than metal. was there.

[0007] The present invention solves the drawbacks of the prior art, and makes it possible to heat the core material of not only metal but also other materials in advance, thereby curing the portion of the reinforcing fiber in contact with the core material. The purpose of this invention is to provide a molding method that prevents the delay in production, thereby providing good adhesion between the core material and the fiber-reinforced synthetic resin layer, and without sacrificing productivity.

[0008]

[Means for Solving the Problems] The present invention supplies a thermosetting resin that hardens at a relatively low temperature to the surface of the core material while transporting the core material in one direction, and supplies the thermosetting resin that hardens at a relatively low temperature to the outer periphery of the core material. The gist of this invention is a method for forming a fiber-reinforced synthetic resin composite, characterized in that a fiber-reinforced synthetic resin layer is formed by supplying reinforcing fibers impregnated with a thermosetting resin and pultrusion molding the reinforcing fibers.

[0009] Examples of the thermosetting resin that is supplied to the surface of the core material and cures at a relatively low temperature used in the present invention include di-benzoyl peroxide, lauroyl peroxide, and t-butyl peroxide. Examples include unsaturated polyester resins to which peroxides (generally referred to as medium-temperature initiators) such as ethylhexanoate and t-butylperoxyneodecanoate are added, and the viscosity of these resin liquids is increased from 500 to 500. It is used after adjusting to 2000 cps.

In the present invention, the method for supplying and applying the thermosetting resin that hardens at a relatively low temperature to the core material is as follows:
Although it depends on the shape of the core material, the method of passing the core material into the resin liquid tank and the stage where the core material is being transferred with a pinch roller,
Examples include a method of dripping a resin liquid onto the surface of the pinch roller and transferring it to the core material, or a combination of these methods. Since the resin applied to the surface of the core material is at a stage before curing, there is a risk that it will flow down at this stage, so its viscosity is adjusted as described above.

The materials forming the core material of the present invention include metal, wood, ceramics, various synthetic resins, various fiber-reinforced synthetic resins, foams of these synthetic resins, etc., and the shape thereof is not particularly limited. It may also be a hollow product or a solid product.

Examples of reinforcing fibers used in the fiber-reinforced synthetic resin layer of the present invention include rovings, chopped strand mats, cross mats, laminated mats, etc. made of glass fibers, carbon fibers, and organic fibers. Each can be used alone or both can be used in combination.

Examples of the types of resins that harden at relatively high temperatures used in the fiber-reinforced synthetic resin layer of the present invention include dicumyl peroxide, t-butyl peroxybenzoate, di-t-butyl peroxide, etc. Examples include thermosetting resins such as unsaturated polyester resins and epoxy resins to which a high temperature initiator (referred to as a high temperature initiator) is added.

In the present invention, in order to impregnate the reinforcing fibers with the thermosetting resin, there is a method in which the reinforcing fibers are impregnated by passing through a resin liquid tank in the process before being fed into the molding mold, and an opening in the molding passage of the molding mold is used. Other known methods, such as a method of impregnating the resin liquid by sending the resin liquid through the resin liquid insertion port, may be employed.

[0015] The molding die used in the present invention can be the mold used in conventional pultrusion molding methods, and the heat source can be heating using infrared rays or high frequency in addition to heat media such as electric heat or oil. The temperature is usually adjusted to 100 to 200° C. using these heat sources.

In the present invention, other conventionally known pultrusion molding methods can be used as is, and after heating and hardening in a molding die, the composite is cut with a draw cutter to a fixed length. And it is sufficient. Molding speed is usually 0.1-2
Preferably, the speed is m/min.

[0017]

[Operation] The present invention supplies a thermosetting resin that hardens at a relatively low temperature to the surface of the core material while transporting it in one direction, and supplies a thermosetting resin that hardens at a relatively high temperature to the outer periphery of the core material. Since the impregnated reinforcing fibers are supplied and pultruded, the thermosetting resin contained in the reinforcing fibers, which hardens at a relatively high temperature, is not only cured in the mold, but also the core material is hardened. The thermosetting resin that is applied to the surface and cures at a relatively low temperature also undergoes a curing reaction, and the heat of the curing reaction raises the temperature of the core material. Therefore, reinforcing fibers impregnated with a thermosetting resin that hardens at relatively high temperatures are heated not only by the mold but also by the core material, which reduces the variation in temperature distribution in the thickness direction that the molding material receives in the heat-hardening section. In particular, the temperature difference between the temperature received from the wall surface of the mold and the temperature received from the portion in contact with the core material is reduced.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic explanatory diagram showing an example of the molding process when carrying out the method for molding a fiber-reinforced synthetic resin composite of the present invention.

In FIG. 1, reference numeral 1 denotes a pipe-shaped core material made of urethane resin foam, which is continuously transported in the direction of the arrow. 2 is a liquid tank into which an unsaturated polyester resin liquid 3 that hardens at a relatively low temperature is poured. Packings 4 and 4 are attached to the through holes provided at the front and rear of the liquid tank through which the core material 1 enters and exits, and have the function of a seal, and the front packing 4 has the function of squeezing out excess resin liquid applied. It also fulfills the following. 5, 5... are glass rovings unwound from a bobbin, and are immersed in a liquid tank 7 into which an unsaturated polyester resin liquid 6 that hardens at a relatively high temperature is injected. Reference numeral 8 denotes an alignment device (guide plate) that aligns the core material 1, the glass roving 5, a continuous mat 9 described later, etc. in a predetermined direction of movement. The continuous mats 9, 9 are unwound from the bobbin and are also shaped by the shaping device 8.
A glass roving 5 is placed around the outer circumference of the core material 1 while passing through the core material 1.
They are arranged in such a way that they each cover half a circumference in the circumferential direction. In this embodiment, the continuous mats 9, 9 are arranged only on the outermost layer. A molding die 10 is provided with a molding passage (not shown). Furthermore, 1
1 is a take-up device, and 12 is a cutter that moves up and down in the direction of the arrow.

With such a device, first, the core material 1 is continuously transferred in the molding direction and introduced into the liquid tank 2, and the unsaturated polyester resin liquid 3, which hardens at a relatively low temperature, is applied to the surface of the core material 1. Apply to. Further, while letting out the glass rovings 5, 5, they are guided into a liquid tank 7, impregnated with an unsaturated polyester resin liquid 6 that hardens at a relatively high temperature, and guided to the outer peripheral surface of the core material 1 by an alignment device 8, Continuous mat 9
, 9 are let out and stacked on the glass rovings 5, 5 by the same aligning device 8. When fed into the molding die 10 in this manner, the reinforcing fibers such as the glass roving 5 and the continuous mat 9 are heated by heat transfer from the walls of the molding channel, and are also coated on the surface of the core material 1. Since the unsaturated polyester resin layer, which is cured at a relatively low temperature, is also heated and cured, it is also heated and cured by heat transfer from the core material 1 whose temperature is raised by the reaction heat. The molding material heated and hardened in this way is transferred to the take-off device 1.
1 and cut into regular lengths by a cutter 12. The obtained material has a core material layer 13, a thermosetting resin layer 14 made of an unsaturated polyester resin that hardens at a relatively low temperature formed around the core material layer 13, and a fiber-reinforced synthetic resin layer 15 that are firmly integrated. It forms a three-layered composite.

Experimental Example A composite was molded based on the configuration shown below. This experimental example was also compared with a conventional method, ie, a case where an unsaturated polyester resin that cures at a relatively low temperature was not applied. 1) Molding material ■. Core material = 30 times foamed polyurethane round rod, each measuring 30 mm (inner diameter) x 2 mm (thickness) x 2 m (length)■. Unsaturated polyester resin that hardens at relatively low temperatures = 3512 manufactured by Nippon U-Pica, with dibenzoyl peroxide added as a hardening agent. ■. Reinforcement fibers = No. 4500 glass roving (manufactured by Asahi Fiber Co., Ltd.) and No. 450 continuous mat (manufactured by Asahi Fiber Co., Ltd.) ■. Unsaturated polyester resin that hardens at a relatively high temperature = 312 manufactured by Nippon U-Pica with t-butyl peroxybenzoate added as a hardening agent 2) Molding device The device shown in Figure 1 First, the core material 1 is melted into a liquid. Unsaturated polyester resin liquid 3 passed through layer 2 and cured at a relatively low temperature on its surface.
Next, while guiding the glass roving 5 impregnated with a resin liquid that hardens at a relatively high temperature around the core material 1,
Furthermore, continuous mats 9, 9 are arranged in the outermost layer, and the reinforcing fibers made of these are combined with the core material 1 to 15
It was fed into a molding die 10 set at 0° C. and cured by heating. The molding speed at this time was 0.7 m/min, and the thermosetting resin layer 14 and the fiber-reinforced synthetic resin layer 1 were
The adhesion strength at the interface with No. 5 was 0.75 Kg/mm2.

As a comparative production method, molding was performed in the same manner as in Experimental Example 1 at the same molding speed, except that the unsaturated polyester resin liquid 3, which hardens at a relatively low temperature, was not applied to the surface of the core material 1. When the adhesion strength of the interface of the obtained test piece was measured, it was 0.2 Kg/mm2. In addition, the adhesion strength is AST
Measured according to MC273-61.

[0023]

Effects of the Invention The molding method of the present invention supplies a thermosetting resin that hardens at a relatively low temperature to the surface of the core material while transporting it in one direction, and supplies a thermosetting resin that hardens at a relatively high temperature to the outer periphery of the core material. Since reinforcing fibers impregnated with hardening resin are supplied and pultruded, in the molding mold, the thermosetting resin contained in the reinforcing fibers, which hardens at relatively high temperatures, not only hardens. The thermosetting resin, which is supplied to the surface of the core material and cures at a relatively low temperature, also undergoes a curing reaction, and the temperature of the core material is raised by the reaction heat of the curing. Therefore, reinforcing fibers impregnated with a thermosetting resin that hardens at relatively high temperatures are heated not only by the mold but also by the core material, which reduces the variation in temperature distribution in the thickness direction that the molding material receives in the heat-hardening section. In particular, the temperature difference between the temperature received from the wall surface of the mold and the temperature received from the portion in contact with the core material is reduced. Therefore,
Correspondingly, the curing phenomenon of the resin progresses not only from the part in contact with the mold but also from the part in contact with the core material, and the curing time becomes faster, and the resin hardens at each depth in the thickness direction of the fiber-reinforced synthetic resin layer. The curing speed is made uniform, and resin impregnation failure due to curing shrinkage does not occur at the interface between the core material layer and the fiber-reinforced synthetic resin layer, and a product of excellent quality can be obtained quickly and stably.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an example of a molding process when carrying out the method for molding a fiber-reinforced synthetic resin composite of the present invention.

[Explanation of symbols]

1 Core material 2 Resin liquid tank 3 filled with thermosetting resin liquid that hardens at relatively low temperatures Thermosetting resin liquid 4 that hardens at relatively low temperatures
Packing 5 Glass roving 6 Thermosetting resin liquid that hardens at relatively high temperatures 7
Resin liquid layer 9 injected with thermosetting resin liquid that hardens at a relatively high temperature Continuous mat 10 Molding mold 11 Taking-off device 12 Cutter 13 Core material layer 14 Thermosetting resin layer 15 of unsaturated polyester resin that hardens at a relatively low temperature Fiber reinforced synthetic resin layer

Claims (1)

[Claims] [Claim 1] While transporting the core material in one direction, a thermosetting resin that hardens at a relatively low temperature is supplied to the surface of the core material, and the outer periphery thereof is impregnated with a thermosetting resin that hardens at a relatively high temperature. A method for forming a fiber-reinforced synthetic resin composite, comprising forming a fiber-reinforced synthetic resin layer by supplying reinforcing fibers and pultrusion molding.