JPH082606B2 - Fiber-reinforced phenolic resin foam and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fiber-fiber-reinforced phenolic resin foam having a sandwich structure having a foamed resin layer inside and a method for producing the same, and more specifically, for example, The present invention relates to a fiber-reinforced phenolic resin foam useful as an interior material for automobiles, railway vehicles, ships, airplanes, etc., or as an interior material for houses, and a method for producing the same.

(B) Problems to be Solved by Conventional Techniques and Inventions Phenolic resins are excellent in heat resistance and fire resistance, and are used in various building materials by paying attention to these characteristics. It is a well-known fact that recently, various composites of phenol foam and glass fiber have been carried out for the purpose of lightweight and high strength. For example, JP-A-63-172616 and JP-A-63-3051
46, JP-A 64-22508, JP-A 64-22513, and others. The inventions described in these publications are obtained by laminating a sheet-like material obtained by impregnating a class E glass fiber coated with an acid-resistant resin with a resole-type expandable phenol resin and degassing with a grooved roll or the like, and heating the laminated sheet-like material. It is characterized in that a molded product having glass fibers uniformly present in the thickness direction is obtained by foaming and hardening while compressing with a roll or the like in a furnace.

However, in the case of forming a thick molded body by such a method, it is necessary to stack a number of layers. Therefore, in this case, the thicker the molded body, the more devices and the more complicated it becomes. Further, when stacking layers in stages, the length of the manufacturing line becomes longer as the thickness increases. Further, in order to simplify the manufacturing apparatus, if a thin molded body is sliced from a thick molded body to obtain a laminated plate produced by the above method, the interface peels due to the slicing process. In addition, there is a disadvantage that chips such as chips are lost.

On the other hand, after impregnating a synthetic resin foam with a thermosetting resin stock solution, laminating glass fibers on at least one surface, and then compressing the resin stock solution, the impregnation method is performed by squeezing the synthetic resin foam from the synthetic resin foam. This is a known fact. For example, it is described in Reservoir Molding (PRChant: FRP General Lecture Lecture Collection, 17 (Showa 47), P.149, Reinforced Plastic Technology Association), JP-A-58-20419, and others. The invention described in these publications is such that a soft sponge having open cells thicker than the final molding thickness is sufficiently impregnated with the thermosetting resin stock solution, and then the surface is covered with a glass mat or the like and compressed at low pressure. In this way, the glass fiber layer is impregnated by squeezing out the resin, and in particular, JP-A-58-21419 is characterized by complete defoaming inside the resin stock solution tank by means of rolls.

However, this publication merely starts a non-foaming epoxy resin or an unsaturated polyester resin as a thermosetting resin, and does not relate to a foaming thermosetting resin.

Under such circumstances, the present inventors have conducted an examination to apply the above method to the production of a surface fiber reinforced phenol resin foam having a foam layer in the core. However, making the core layer a foam layer means that the absolute amount of the impregnating resin in the soft sponge becomes small. Therefore, as a matter of course, the amount of squeezing out by compression is not sufficient for the glass fiber layer as in the case of non-foaming, and therefore the impregnation is insufficient, so that the strength becomes low. Also,
In the case of an acid-curable phenol resin, the resole resin itself as a starting material has a high viscosity, and therefore the restoring force of the soft sponge alone does not restore the set thickness.

(C) Means for Solving the Problems Thus, according to the present invention, after the soft sponge is impregnated with the resole-type expandable phenol resin stock solution, reinforcing fibers are arranged on both surfaces of the soft sponge, and then the foam is formed in a predetermined mold. Provided is a method for producing a fiber-reinforced phenol resin foam, which comprises subjecting a stock phenolic resin solution to foaming and curing conditions to obtain a fiber-reinforced phenol resin foam.

This invention is a fiber-reinforced phenol having excellent strength by performing foam molding with reinforcing fibers on both sides without performing a step of squeezing the expandable phenol resin stock solution impregnated in a soft sponge into reinforcing fibers. It was made by finding the fact that a resin foam can be integrally molded.

According to this invention, compared to the conventional method, the thickness of the laminating step is always constant even if the thickness changes, and the thickness can be freely adjusted by changing the thickness of the soft sponge. Since there is always one, the loss of the resol type foamable phenol resin stock solution can be reduced. Therefore, the manufacturing apparatus can be simplified and the existence of the bonding interface, which can be a weak point of strength, can be minimized.

The fiber-reinforced phenolic resin foam produced by the above method comprises a soft sponge layer filled with a phenolic resin foam, and a core layer formed on both sides of the core layer. It is provided with a surface layer composed of a body and / or a non-foamed body, and is novel per se. Therefore, this invention
The present invention also provides a fiber-reinforced phenolic resin foam having such a sandwich structure.

The soft sponge used in this invention may have any composition as long as it has open-cell flexibility.
For example, soft urethane sponge, cellulose sponge,
Various materials such as sponges, especially sheet-shaped materials can be used.

Examples of fibers used for the purpose of reinforcement in the present invention include glass fibers, and as the shape thereof, various ones such as chopped strands, sheets, papers, mats, rovings, cloths, tricots, and webs can be used. However, in general, it is preferable to use a mat or cloth, and it is particularly preferable to use a chopped strand mat, a glass cloth, or a roving cloth. Examples of modification of this glass fiber include silane treatment, and particularly, aminosilane-based materials. It is preferable to treat with. In some cases, metal fibers such as stainless steel fibers, organic fibers such as carbon fibers and aromatic polyamide fibers can be used.

In the present invention, the resol type foamable phenol resin stock solution used is obtained, for example, by mixing a resol type phenol resin, a curing agent, a foaming agent and a neutralizing agent. The compounding ratio of the curing agent and the foaming agent may be set according to the mixing method and the density of the molded product to be manufactured. Further, if necessary, it is possible to mix an extender and the like.

Examples of the curing agent include organic sulfonic acids such as phenol sulfonic acid, paratoluene sulfonic acid, and xylene sulfonic acid. Some glass fibers have strong alkalinity and inhibit curing with an acid curing agent. In that case, it can be solved by subjecting the glass fibers to an acid treatment in advance. The weighed amount of glass fiber usually used is preferably 100 g to 450 g / m ² .

Examples of the foaming agent include saturated aliphatic hydrocarbons such as hexane, pentane and butane, alicyclic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as benzene and xylene, methylene chloride and Freon. One or a mixture of two or more kinds of halogenated hydrocarbons such as (registered trademark) may be mentioned, and it is usually used in an amount of about 0 to 20 parts with respect to the resole resin depending on the bulk density of the intended final product. However, in addition to this, an acid decomposition type foaming agent can also be used.

In the present invention, as a specific method of impregnating the soft resin sponge with the phenol resin stock solution, when the soft sponge is compressed by a biaxial compression roll or the like, a predetermined amount is continuously discharged at a flat die degree before the compression. It is suitable to apply the resol type foamable phenol stock solution directly to a soft sponge and forcibly impregnate it with a roller, or to apply the foamable phenol stock solution to one or both rollers and feed it to impregnate it simultaneously with compression. . Whichever method is used, the above-mentioned method or any method according thereto can be adopted as long as it can uniformly impregnate the above-mentioned soft sponge with the required amount of the expandable phenol resin stock solution.

Both sides of a soft sponge impregnated with such a foamable phenol resin stock solution are covered with glass fibers, and then foam molding is performed. The foam molding is carried out by heating in a suitable mold, and as this mold, it is usually suitable to use a double-sided guide shape that regulates arbitrary foaming in both directions. Therefore, it is usually suitable to carry out the molding by guiding to a heating zone having such a double-sided guide.

Heating is usually 70 ° C to 90 ° C, although it depends on the thickness of the final molded product. Further, it is possible to provide a preheating zone if necessary.

The foamable phenol resin stock solution inside the soft sponge is foamed and cured by such heating, whereby the phenol resin penetrates into the glass fiber, and as a result, the intended fiber-reinforced phenol resin foam having a sandwich structure is obtained. . Here, since the surface layer is subjected to pressure by the mold, that is, double-sided pressing and foaming pressure during formation, the density is improved and the density is higher than that of the internal phenolic foam and the foam layer or the substantially non-foamed layer is reinforced. It is composed of a composite layer in which fibers are integrated.

The fiber-reinforced phenolic resin foam thus obtained is usually composed of a relatively high-density phenolic resin foam reinforced with glass fibers or a non-foaming surface layer and a low-density phenolic foam layer. , Bulk density of 0.2 ~
It is composed of a core layer of 1.0 g / cm ³ , is lighter in weight than conventional phenol FRP, has relatively high strength, and has heat insulation performance and sound absorption.

The first example of the fiber-reinforced phenolic resin foam of the present invention
As shown in the figure. As shown in the figure, the fiber-reinforced phenolic resin foam 1 of the present invention comprises a core layer 3 made of a phenolic resin foam and a soft sponge, and a surface layer 2 made of a glass fiber-reinforced phenolic resin foam.

The fiber-reinforced phenolic resin foam of the present invention is useful as an automobile interior material, a home interior material, and the like. In particular, a lightweight material having a bulk density of 0.5 g / cm ³ or less is useful as a sound insulation material for automobiles.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

(D) Example Example 1 A glass chopped strand mat for unsaturated polyester FRP (manufactured by Fuji Fiber Glass Co., Ltd.) having a basis weight of 300 g / m ² was heat-cleaned, and then a silane coupling material (trade name KBM602 manufactured by Shin-Etsu Silicone Co., Ltd.) 1 % Aqueous solution, air-dried, and then dried at 100 ° C. for 10 minutes.

In the preparation of the foamable resol resin stock solution, the curing agent was adjusted to 16 parts by weight, the foaming agent to 7 parts by weight, and the neutralizing agent to 30 parts by weight with respect to 100 parts by weight of the resole resin.

As shown in Fig. 2, while compressing soft urethane foam 4 having a thickness of 5 mm, a width of 1 m and a bulk density of 14 kg / m ³ with a pair of rollers 5a and 5b, foam extruded by a phenol mixing and discharging machine 6 before the compression. Resol resin undiluted solution 7 is uniformly discharged in the width direction at a rate of 2.2 kg / m ² by a flood die 8 to impregnate a soft urethane foam (soft sponge), and then the glass chopped strand mat 9 is laminated on the foam surface. Heating and foaming furnace 11 while pressurizing with double steel belt 10
Was heated at about 90 ° C. to foam and cure.

When the characteristics of the obtained fiber-reinforced phenolic resin foam were examined, it was found that the foam had a thickness of 5 mm, the fiber-reinforced layers were 0.7 mm each on the front and back sides, the foam layer was 3.6 mm, the bulk density was 500 Kg / m ³ , and the bending strength was 400 Kg.・ F / cm ² , tensile strength of 90 kg ・ f / cm ² , surface hardness of 55 degrees (Type D), and normal incident sound absorption coefficient (Table 1) were found. In addition, the obtained fiber-reinforced phenolic resin foam
As a result of exposing for 500 hours in an atmosphere of 200 ° C, the initial bending strength was
As a result of calculating the retention rate using the following formula as 100%,
The flexural strength retention was about 62%. The flexural modulus retention rate and the weight retention rate were calculated by the same calculation formula, and the results were that the flexural modulus retention rate was about 90% and the weight retention rate was about 90%.

The fiber-reinforced phenolic foam obtained had little variation in resin density between the front and back, and warpage did not occur.

Example 2 A weighed 450 g / m ² glass chopped strand mat was treated in the same manner as in Example 1, and a soft urethane foam having a thickness of 2 mm, a width of 1 m and a high density of 20 kg / m ³ was used in the same manner as in Example 1, The expandable resol resin stock solution was discharged so as to be 1200 g / m ² , and the above mats were laminated one by one on the front and back, and continuously molded.

When the characteristics of the obtained fiber-reinforced phenolic resin foam were examined, the thickness of the fiber-reinforced layer was 3 mm and the fiber-reinforced layer was 0.9 mm on each side, and the foam layer was 1.2 mm, the high density was 650 kg / m ³ , and the bending strength was 620 kg / f /.
It was found to show cm ² .

Comparative Example 1 Under the same composition and conditions as in Example 1, only the flexible urethane foam was removed, and the foamable resole resin stock solution was directly impregnated into the lower surface glass chopped strand mat to obtain a molded body.

When the properties of the obtained fiber-reinforced phenolic resin foam were examined, the foam had a high density of 500 Kg / cm ³ , but
Of the thickness of 5 mm, the lower fiber reinforced layer caused a corrugation phenomenon, resulting in a thickness of 1.2 mm, and the upper fiber reinforced layer had a thickness of 0.7 mm, which was a non-uniform molded body and warped.

Comparative Example 2 Under the same composition and conditions as in Example 1, except for the blowing agent, the thickness 10
After impregnating a soft urethane foam with a thickness of 5 mm and covering it with a glass chopped strand mat, the glass fiber layer compressed to a thickness of 5 mm was impregnated into a fiber-reinforced phenolic resin foam, which was hardly seen.

(E) Effect of the Invention As described above, according to the present invention, it is possible to easily obtain a fiber-reinforced phenolic resin foam having a predetermined thickness, and it is uniform in the vertical direction from the center in the thickness direction to the surface layer. A fiber-reinforced phenolic resin foam can be obtained.
Furthermore, since the surface layer and the core layer can be freely combined according to the required strength and quality, they are particularly useful for heat insulating materials and sound absorbing materials.

[Brief description of drawings]

FIG. 1 shows an example of the fiber-reinforced phenolic resin foam of the present invention. FIG. 2 is an explanatory view illustrating the manufacturing steps in the method for manufacturing a fiber-reinforced phenolic resin foam of the present invention. 1 ... Fiber reinforced phenolic resin foam, 2 ... Surface layer, 3 ... Core layer, 4 ... Soft urethane foam, 5 ... Roller, 6 ... Mixing discharge machine, 7 ... Foamable resole resin stock solution, 8: Flat die, 9: Glass chopped strand mat, 10: Double steel belt, 11: Heating foaming furnace.

Claims (2)

[Claims] 1. A core layer formed by filling a soft sponge layer with a phenol resin foam, and reinforcing fibers and a phenol resin foam and / or a non-foam formed on both surfaces of the core layer. A fiber-reinforced phenolic resin foam comprising a surface layer. 2. A soft sponge is impregnated with a resole-type expandable phenol resin stock solution, reinforcing fibers are placed on both sides of the soft sponge, and then the foamable phenol resin stock solution is subjected to foaming and curing conditions in a predetermined mold. A method for producing a fiber-reinforced phenolic resin foam, which comprises obtaining the fiber-reinforced phenolic resin foam according to claim 1.