JPH04301435A - Method for molding fiber-reinforced synthetic resin composite - Google Patents

Abstract

PURPOSE:To prevent quality from deterioration and production speed from lowering by coating the surface of a core material with a low temp.-curable thermosetting resin, curing the coated surface by heating through a release film, feeding a reinforcing fiber impregnated with a relatively high temp. curable thermosetting resin around it and performing pultrusion. CONSTITUTION:A core material 1 is continuously transferred in the molding direction and the surface is coated with a low temp.-curable unsatd. polyester resin soln. 3 and 3'. Then, release films 5 and 5' are guided on the coated surface at an approximately same speed and they are adhered on the coated surface by utilizing tackiness of the coated surface to cover it. Successively, the unsatd. polyester resin soln. 3 and 3' are heated and cured through the release films 5 and 5' by irradiating it with far infrared rays from a far infrared rays heating apparatus 6 and 6'. A composite body with a bi-layered structure wherein the core material layer 13 and the thermosetting resin layer 14 formed aroung its outer peripheral face are strongly integrated, is formed thereby.

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, various methods have been known for forming fiber-reinforced synthetic resin moldings, among which pultrusion molding allows continuous molding and is capable of producing long lengths with various cross-sectional shapes. It is attracting attention because it can efficiently produce the body.

In particular, when a molded body is formed by a pultrusion method, there is a large difference in strength between the drawing direction and the direction perpendicular to this, which limits the applications of the molded body. A commonly used molding method eliminates this drawback by forming a composite material with a fiber-reinforced synthetic resin layer and using an isotropic core material. The pultrusion method not only improves directionality, but also allows the above-mentioned cross-sectional shape to be set arbitrarily by combining various types of resin and fiber materials for the core material and outer layer, thickness of each layer, etc. In combination, it is possible to obtain desired strength, weight, and other physical properties, and it is an excellent technology in that it is easy to obtain products with reasonable properties depending on the intended use.

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

[0005] Therefore, the curing phenomenon of the resin progresses from the part in contact with the mold, and the curing of the part in contact with the core material is delayed the most.Due to the non-uniformity of the curing speed of the resin in this outer layer part, the hardening of the resin progresses from the part in contact with the mold. Poor resin impregnation occurs due to curing shrinkage at the interface between the core layer and the fiber-reinforced synthetic resin layer, resulting in voids, nests, etc., resulting in poor adhesion between the core material layer and the fiber-reinforced synthetic resin layer, resulting in a decrease in strength. A problem arises that causes
If you try to keep the molding speed as low as possible to ensure sufficient curing of the part that contacts the core material, the thicker the fiber-reinforced synthetic resin layer becomes, the slower the molding speed becomes, making it difficult to achieve the desired production speed. There was also the problem of not being able to

[0006] 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 nonexistent, thus making it possible to equalize the curing speed of the thermosetting resin that is the outer layer. This technology is attracting attention because it can prevent quality deterioration and production speed reduction caused by non-uniformity.

[0007]

[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.

[0008] 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 that comes into 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.

[0009]

[Means for Solving the Problems] The present invention applies a thermosetting resin that hardens at a relatively low temperature to the surface of the core material while transferring it in one direction, and then coats the coated surface with a release film. After heating and curing the fiber, a reinforcing fiber impregnated with a thermosetting resin that hardens at a relatively high temperature is supplied around the outer periphery and pultrusion molding is performed to form a fiber-reinforced synthetic resin layer. The gist of this paper is a method for molding reinforced synthetic resin composites.

Materials forming the core material of the present invention include metal, wood, ceramic, various synthetic resins, various fiber-reinforced synthetic resins, foams of these synthetic resins, etc. The material is not particularly limited, 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 resin that hardens at a relatively high temperature for use 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.

[0013] As the thermosetting resin which is applied to the surface of the core material and cures at a relatively low temperature, for example, di-benzoyl peroxide, lauroyl peroxide, t-butylperoxy 2-ethyl, etc. are used in the present invention. Examples include unsaturated polyester resins to which peroxides (generally referred to as intermediate temperature initiators) such as hexanoate and t-butylperoxyneodecanoate are added, and the viscosity of these resin liquids is increased to 500 to 2000 cps. Adjust and use.

In the present invention, the method for applying the thermosetting resin that hardens at a relatively low temperature to the core material depends on the shape of the core material, but the method is to pass the core material into a resin liquid bath. Method,
Examples include a method in which resin liquid is dripped onto the surface of a pinch roller inserted into the core material while the core material is being transferred and transferred to the core material, or a combination of these methods is used. Then, in order to coat the surface of the core material with as uniform a thickness as possible,
Immediately after coating, it is preferable to press the coated surface through a pinch roller having a shape corresponding to the surface shape of the core material to roll the coated resin. The resin applied to the surface of the core material is viscous, but since it has not yet hardened, there is a risk of it flowing down, and to prevent this, a release film is applied. .

The release film used in the present invention is preferably a synthetic resin film having heat resistance and release properties, such as polytetrafluoroethylene. In order to be able to use the film repeatedly, it is preferable to collect it after use, or to equip it in the form of an endless belt so that it can run repeatedly on the surface of the core material.

In the present invention, heating methods for heating the coated surface of the thermosetting resin that hardens at a relatively low temperature via a release film include passing it through a heating furnace;
Examples include a method of radiant heating by arranging infrared lamps or far-infrared lamps around the core material.

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.

[0018] 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, any other conventionally known pultrusion molding method 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.

[0020]

[Operation] In the present invention, a thermosetting resin that hardens at a relatively low temperature is applied to the surface of the core material while being transferred in one direction, and the coated surface is heated and hardened through a release film. rear,
By supplying reinforcing fibers impregnated with a thermosetting resin that hardens at a relatively high temperature to the outer periphery, pultrusion molding is performed.
The temperature of the core material is raised by the heat of reaction during curing of a thermosetting resin that hardens at a relatively low temperature, and the reinforcing fibers impregnated with resin guided around the core material are placed inside the molding mold together with this core material. The molding material is introduced into the molding passageway and is heated and hardened not only by the mold but also by the core material. Therefore, in the temperature distribution in the thickness direction that the molding material receives in the heat-hardening section, the temperature received from the wall surface of the molding mold and the core material are different. The temperature difference between the temperature received from the part in contact with the material is reduced.

[0021]

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. Reference numerals 2 and 2' designate an upper liquid tank and a lower liquid tank into which unsaturated polyester resin liquids 3 and 3', which harden at relatively low temperatures, are injected, respectively. Reference numerals 4 and 4' denote a pair of applicator rollers, whose rotating body circumferential surfaces both have a semicircular shape corresponding to the cross-sectional shape of the core material 1, and each covers approximately half the circumference of the core material 1 in the circumferential direction. It is driven by a driving force different from that of the core material 1 while being pressed from above and below. The surface of the coating roller 4 is made to be able to be coated by casting the unsaturated polyester resin liquid 3 from the upper liquid tank 2 and transferring it from the coating roller 4 to the upper half of the core material 1. , the coating roller 4' is immersed in the lower liquid tank 2', and the unsaturated polyester resin liquid 3' is drawn onto the roller surface,
This can be applied by transferring it to the lower half of the core material 1. Reference numerals 5 and 5' denote release films to be applied to the surface of the core material 1 after the unsaturated polyester resin liquid is applied thereto, and are unwound from a separately installed reel. When applying the coating, it is possible to wrap the coating by bending it in the circumferential direction from above and below along the application surface using a shaping plate (not shown). 6, 6' are far-infrared devices, 7 is a molding die, 8, 8'... are reinforcing fibers made of glass roving, continuous mat, etc. unwound from a bobbin (not shown), and in this example, the outermost layer Continuous mats are now placed only in those areas. These reinforcing fibers are aligned by alignment devices (guide plates) 9, 9', and pass through resin liquid tanks 10, 10' filled with liquid unsaturated polyester resin liquid that hardens at relatively high temperatures. Then, it is guided to the outer periphery of the core material 1 before the molding die 7. 11 is a take-up device, and 12 is a cutter that moves up and down in the direction of the arrow.

Using such an apparatus, first, while the core material 1 is continuously transferred in the molding direction, the unsaturated polyester resin liquid 3, 3', which hardens at a relatively low temperature, is applied to the surface of the core material 1. Next, release films 5, 5' are introduced onto the coated surface at approximately the same speed, and are adhered to the coated surface using the adhesive properties of the coated surface to cover it. Subsequently, far infrared rays are irradiated from the far infrared heating devices 6 and 6' to heat and harden the unsaturated polyester resin liquids 3 and 3' through the release films 5 and 5'. Thus, the core material 1 is heated by the heat of reaction at that time. Then, the release films 5, 5' are peeled off from the coated surface and recovered again, while the core material 1 is transported as it is in the molding direction. Then, on the circumferential surface of the core material, an alignment device (guide plate )9
, 9', etc., the array is arranged and guided, and sent to the molding die 7. Here, the molding material such as reinforcing fibers is heated by heat transfer from the wall surface of the molding channel, and is also heated by heat transfer from the core material 1, which has already been heated and raised in temperature, and the resin is hardened. . The molding material heated and hardened in this manner is taken off by a take-off device 11 and cut into regular lengths by a cutter 12. The obtained product forms a two-layer composite in which the core material layer 13 and the thermosetting resin layer 14 formed around the outer periphery of the core material layer 13 are firmly integrated.

Experimental Example Using the molding apparatus shown in FIG. 1, a composite was molded based on the configuration shown below. In addition, this experimental example was performed using the conventional method,
That is, a comparison was made with a case in which an unsaturated polyester resin that hardens at a relatively low temperature was not applied. 1) Molding material ■. Core material: A pipe-shaped body made of 30 times foamed polyurethane, each measuring 30 mm (inner diameter) x 2 mm (thickness) x 2 m (length) ■. Unsaturated polyester resin that hardens at a relatively low temperature = Ester 2 manufactured by Mitsui Toatsu Co., Ltd. with bis(t-butylcyclohexyl) peroxydicarbonate added as a hardening agent
35 ■. 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 = U-Pica 3512 manufactured by Nippon U-Pica, to which methyl ethyl ketone peroxide is added as a curing agent ■. Release film = Teflon film with a thickness of 0.2 mm 2) Molding device The device shown in Fig. 1 First, an unsaturated polyester resin liquid that hardens at a relatively low temperature is applied to the surface of the core material 1, and a far infrared ray of 10 Kw is applied. The device was heated for 1 minute. The resin liquid undergoes a curing reaction, and the surface temperature is 120°C due to the reaction heat at that time.
This temperature was maintained almost until the material was inserted into a mold, which will be described later. Next, while guiding 100 glass rovings around the core material 1 that has been preheated in this way, a continuous mat is further arranged as the outermost layer, and the reinforcing fibers made of these are heated together with the core material 1 at 150°C. The mixture was fed into a molding die 7 set at 1 and heated to harden. The adhesion strength of the interface between the core material layer 13 and the fiber-reinforced synthetic resin layer 14 in the sampled test piece 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 that hardens at a relatively low temperature was not applied to the surface of the core material 1. When the adhesion strength of the interface was measured for the obtained test piece, it was found that
It was 0.2Kg/mm2. In addition, the adhesion strength is ASTM
Measured in accordance with C273-61.

[0026]

Effects of the Invention: The molding method of the present invention applies a thermosetting resin that hardens at a relatively low temperature to the surface of the core material while transferring it in one direction, and then heats the coated surface via a release film. After curing, reinforcing fibers impregnated with a thermosetting resin that hardens at a relatively high temperature are supplied to the outer periphery and pultrusion molding is performed.The core material is a thermosetting resin that hardens at a relatively low temperature. The reinforcing fibers impregnated with resin are heated by the reaction heat during curing, and the reinforcing fibers impregnated with resin are led to the outer periphery and are introduced into the molding channel in the molding mold together with this core material, and are not only in the mold but also in the molding mold. Since the core material is also heated and hardened, the temperature distribution in the thickness direction that the molding material receives in the heat-hardening section,
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, 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 hardening phenomenon at each depth in the thickness direction of the reinforced resin progresses. The curing speed is uniform, and there is no resin impregnation failure due to curing shrinkage at the interface between the core material and the fiber-reinforced synthetic resin layer, and high quality products can be quickly produced.
Obtained stably.

[Brief explanation of drawings]

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 Upper liquid tank 2' Lower liquid tank 3, 3' Thermosetting resin liquid 4 that hardens at a relatively low temperature,
4' Application rollers 5, 5' Release films 6, 6' Heating device 7 Molding molds 8, 8' Reinforcing fibers 10, 10' Resin liquid tank 11 injected with thermosetting resin liquid that hardens at relatively high temperatures Taking-off device 12 Cutter 13 Core material layer 14 Fiber-reinforced synthetic resin layer

Claims (1)

[Claims] Claim 1: While transferring the core material in one direction, a thermosetting resin that hardens at a relatively low temperature is applied to the surface of the core material, and the coated surface is heated and hardened through a release film, and then, 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 that hardens at a relatively high temperature to the outer periphery and pultrusion molding the reinforcing fibers. .