JPH08216268A - Manufacture of fiber-reinforced phenol resin molding - Google Patents

Abstract

PURPOSE: To manufacture fiber-reinforced resin molding having excellent strength characteristics with excellent productivity by pultrusion molding phenol resin containing xylene modified phenol resin as a main ingredient as impregnating resin. CONSTITUTION: Reinforcing fiber roving 1 and reinforcing fiber mat 2 are continuously passed through an impregnating tank 3 in which xylene modified phenol resin is filled, and cured while continuously pultrusion molding by a puller 6 via a forming unit 2 and a heating mold 5. The resin at the time of the pultrusion molding can be cured only by heating, but when a suitable quantity of calcium oxide is added as curing catalyst, the impregnation to the reinforcing fiber can be reduced, the curing reaction velocity and the crosslinking point density at the time of curing can be enhanced, and fiber-reinforced resin molding having further excellent strength characteristics can be efficiently obtained. Void defect can be further eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for producing a fiber-reinforced phenolic resin molding having excellent strength characteristics by utilizing a pultrusion molding method.

[0002]

2. Description of the Related Art The pultrusion molding method is a molding method in which a reinforcing fiber is impregnated in a resin and then continuously drawn while being cured and molded through a molding die having a heating mechanism. It is widely used as a continuous molding method of a fiber-reinforced resin molded product obtained by compounding various reinforcing fibers such as carbon fiber and a resin such as an unsaturated polyester resin or an epoxy resin.

On the other hand, a phenolic resin has been used for a long time as a composite resin with a reinforcing fiber since it is excellent in heat resistance, combustion resistance, electrical characteristics and the like and is relatively inexpensive. However, compared with unsaturated polyester resin and epoxy resin, phenol resin has a large amount of solvent used to secure a viscosity suitable for impregnation and a large amount of water is generated during the polycondensation reaction, so that the curing time is long, and Adhesion to reinforcing fibers is also low, and fiber-reinforced resin with satisfactory strength characteristics cannot be obtained by the pultrusion molding method (strength as pultrusion molded article is at most about 80% when unsaturated polyester resin is used as impregnating resin). Therefore, when a phenolic resin is used as the impregnating resin, a hand layup method, a prepreg compound molding method, a reaction type injection molding method, etc., which can easily obtain a sufficient impregnation state and a curing time, have been adopted.

However, since all of these methods are batch systems, they have poor productivity and are not suitable for mass production. Therefore, a pultrusion method using a phenolic resin as an impregnating resin has also been proposed (for example, JP-A-2- 182437
No. 2-235726, etc.), these methods cannot avoid insufficient strength due to insufficient curing or impregnation.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to use a phenol resin as an impregnating resin and to obtain a fiber reinforced resin excellent in strength characteristics. It is intended to establish a technique capable of producing a molded body with a high productivity by a pultrusion molding method.

[0006]

Means for Solving the Problems The constitution of the present invention which was able to solve the above-mentioned problems is that when a fiber-reinforced phenolic resin molding is produced by a pultrusion molding method, a xylene-modified phenol resin is used as a main component as an impregnating resin. The main point is to use the phenolic resin. Although it is possible to cure the resin at the time of the above-mentioned pultrusion molding only by heating, if an appropriate amount of calcium oxide is added as a curing catalyst, the curing reaction rate and the curing reaction rate at the time of curing without deteriorating the impregnability to the reinforcing fiber can be achieved. The density of cross-linking points can be increased, and a fiber-reinforced resin molded product having more excellent strength characteristics can be efficiently obtained.

[0007]

The most important reason why the pultrusion molding method is difficult to use in the production of the fiber-reinforced resin molded product using the phenolic resin as the impregnating resin seems to be the characteristics of the phenolic resin itself. That is, since the phenol resin (particularly the resol type phenol resin) has a large number of functional groups, the viscosity of the aqueous solution is high, and in order to obtain a viscosity suitable for impregnation (usually about 8000 cps or less), the concentration of the aqueous solution must be lowered considerably. In addition, a large amount of water is generated by the polycondensation reaction during curing. In order for the impregnated phenolic resin to be completely cured, a large amount of solvent and generated water must be volatilized and removed, and a large amount of heat is consumed to remove them, resulting in a complete cure. It takes a long time or insufficient curing, and further, the volatile moisture becomes bubbles and is left inside the molded body to form void defects, which adversely affect the strength deterioration.

In order to avoid such problems, it is possible to reduce the amount of volatile water content after impregnation by concentrating the phenolic resin in advance and further precondensing it. Becomes highly viscous and impregnation into the reinforcing fibers becomes insufficient, and void defects increase on the contrary. It is also conceivable to heat the concentrated resin in the impregnation tank to reduce the viscosity and promote impregnation.
The pot life of the concentrated phenolic resin under heating conditions is very short, and it thickens and solidifies into a gel in a short time, making it difficult to put it to practical use on an industrial scale.

That is, a general phenolic resin must be made to have a low concentration in order to secure the viscosity necessary for impregnation, and impregnation becomes poor when it is attempted to increase the concentration to reduce the amount of volatile water at the time of curing. There is a problem, and it is considered that this is one of the causes for lowering the strength characteristics of the fiber-reinforced resin molded product.

Therefore, the inventors of the present invention may solve the above problems at once by using a phenolic resin having a low viscosity as a resin solution and capable of exhibiting an excellent impregnating property at a high concentration. Therefore, we investigated the relationship between concentration and viscosity of various phenolic resins and their suitability as impregnating resins along the line.

As a result, xylene-modified phenol resin can be prepared as a low-viscosity solution by itself among a large number of phenol-based resins, and it has a low viscosity even at a high concentration and an excellent impregnation property as compared with general phenol-based resins. , And it was found that a polycondensation reaction gives a cured product having a high crosslinking point density.

The present invention has been made on the basis of these findings, and a phenolic resin containing a xylene-modified phenolic resin as a main component is used as an impregnating resin, which is combined with a reinforcing fiber by a pultrusion molding method. Fiber reinforced resin moldings are manufactured, and when the conventional phenolic resin is used as the impregnating resin, the curing defects and void defects due to the excess volatile solvent at the time of curing, or the void defects due to the impregnation defect are caused. It is possible to obtain a pultruded molded article which is excellent in strength and heat resistance, because the resin is highly cross-linked and integrated between the reinforcing fibers without any occurrence.

The xylene-modified phenol resin used in the present invention is a polycondensation reaction system of resol type phenol and formaldehyde, and is 0.5 to 1 relative to phenol.
It can be obtained by a method in which xylene is contained in an amount of about 0 times mol and reacted under basic conditions, or a method in which a resol-type phenol / formaldehyde initial condensate and a metaxylene / formaldehyde addition condensation oligomer are reacted, and the like. The xylene-modified phenol resin used in 1. can also be referred to as a phenol-modified xylene formaldehyde resin. In any case, the presence of xylene together with phenol as the polycondensation component markedly reduced the solution viscosity and significantly increased the crosslinking reactivity.

Such a xylene-modified phenolic resin is
For example, the product name "Nikanol P" manufactured by Mitsubishi Gas Chemical Co., Inc.
R-1540M "and" Nikanol PR-1440
M ”or the like.

In the present invention, the xylene-modified phenol resin as described above may be used alone, or may be used as a mixture with another phenol resin. However, when mixed and used, in order to effectively exhibit the characteristics of the present invention, the mixing ratio of the xylene-modified phenol resin is 50% by weight.
As described above, more preferably 70% by weight or more is desired.

The above xylene-modified phenolic resin is used by adjusting the concentration so that the viscosity at 25 ° C. is 3 to 80 poises, more preferably 5 to 50 poises so that the reinforcing fibers can be sufficiently impregnated. Is good. This xylene-modified phenolic resin causes a polycondensation reaction to be cured by heating at 120 to 200 ° C., but if about 1 to 5% by weight of calcium oxide is added to the resin as a curing catalyst, it will be It is preferable because the polycondensation reaction rate can be further increased without increasing the solution viscosity.

Next, the reinforcing fiber used in the present invention has an action of enhancing the strength of the cured product, particularly the tensile strength, the impact strength and the like, and the kind thereof is not particularly limited, but carbon fiber is preferred. , Glass fiber, metal fiber, aramid fiber and the like, which are preferably used as roving, cloth, mat or a combination thereof.

In the present invention, inorganic fillers such as aluminum hydroxide, gypsum, talc, etc., or anti-twisting agents, and ultraviolet light deterioration may be used as other compounding raw materials as long as they do not impair the properties as a pultrusion molding material or the properties of a cured product. It is also possible to mix an appropriate amount of an inhibitor, a pigment, a low-shrinking agent and the like. Further, in order to enhance the pultrudability, it is also effective to add an appropriate amount of an internal release agent.

In the present invention, the above-mentioned blended raw materials are used to perform conventionally known pultrusion molding, for example, pultrusion molding, and heat-cured in parallel with the pultrusion molding or after the pultrusion molding to obtain a cured molded article. For example, FIG. 1 is an explanatory view illustrating a pultrusion molding method, in which a reinforcing fiber roving 1 and a reinforcing fiber mat 2 are continuously placed in an impregnation tank 3 charged with a xylene-modified phenolic resin (or a mixture of this and a curing agent). Through the forming device 4 and the heating die 5, the resin is continuously drawn and cured by the tensile machine 6.
In the figure, 7 indicates a cutting device. It should be noted that FIG. 1 shows only an example of the pultrusion molding method, and does not limit the present invention.

[0020]

【Example】

Example 1 100 parts by weight of a xylene-modified phenol resin (trade name "Nikanol PR-1540M" manufactured by Mitsubishi Gas Chemical Co., Inc.) and an internal mold release agent (trade name "Mold Wi" manufactured by Axel Co.).
z INT-1850 ") 2 parts by weight are charged into a resin tank for impregnation and mixed uniformly, and glass roving (trade name" PER231-FW22 "manufactured by Nippon Glass Fiber Co., Ltd.) is added thereto.
The bundled pieces were passed through and impregnated, and a rod-shaped molded body having a diameter of 10 mm was pultrusion-molded at a mold heating temperature of 200 ° C. at a pultrusion speed of 0.2 m / min using a Pultrex pultrusion molding machine. When the strength of the obtained molded body was measured by a three-point bending test, it was 590 MPa.

Example 2 In the above Example 1, 2 parts by weight of calcium oxide was added to the impregnating resin as a curing catalyst, and the drawing speed was 0.5 m / m.
The rod-shaped molded body was subjected to pultrusion molding in the same manner as in Example 1 except that it was increased to min. The three-point bending strength of the obtained pultrusion molding was 620 MPa.

Example 3 In the above Example 1, "Nikanol PR-154" was used.
50 parts by weight of 0M, 50 parts by weight of a phenol resin (trade name "Dislic-300X" manufactured by Dainippon Ink and Chemicals, Inc.) and 2 parts by weight of calcium oxide are used, and a drawing speed is 0.3.
Pultrusion molding was performed in the same manner as in Example 1 except that m / min was set. The three-dimensional bending strength of the obtained rod-shaped pultrusion molding was 583 MPa.

Comparative Example 1 In the above-mentioned Example 1, "Nikanol PR-15" was used.
A rod-shaped pultrusion molded article was obtained in exactly the same manner except that a phenol resin "Cellobond J2040L" manufactured by BP Chemical Co. was used instead of "40M". The three-point bending strength of this molded product was 315 MPa, which was inferior to the molded product obtained in Example 1 in strength.

Comparative Example 2 In Example 3, the phenol resin "Dislic" was used.
A rod-shaped molded body was obtained in exactly the same manner except that "-300X" was used alone. The three-point bending strength of the molded body is 400
It was MPa, and was inferior in strength to the molded body obtained in Example 3.

[0025]

EFFECTS OF THE INVENTION The present invention is configured as described above, and by using a phenolic resin containing a xylene-modified phenolic resin as a main component as an impregnating resin, it is possible to simultaneously reduce the viscosity during impregnation and increase the concentration. Therefore, it is possible to manufacture a pultrusion molded article having excellent strength characteristics without void defects and the like with high productivity.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view illustrating a pultrusion molding condition used when carrying out the present invention.

[Explanation of symbols]

 1 Reinforcing fiber roving 2 Reinforcing fiber mat 3 Impregnated resin tank 4 Forming device 5 Heating die 6 Drawer 7 Cutter

Claims (2)

[Claims] 1. A fiber-reinforced phenolic resin molding characterized by using a phenolic resin containing a xylene-modified phenolic resin as a main component as an impregnating resin when producing a fiber-reinforced phenolic resin molded product by a pultrusion molding method. How to make a body. 2. The method according to claim 1, wherein calcium oxide is used as a curing catalyst for the phenolic resin.