JPS6375039A - Production of fiber-reinforced phenolic resin molded article - Google Patents

Abstract

PURPOSE:To improve the workability and curability of a resol-type liquid phenolic resin and the color tone, corrosion resistance and mechanical strength of cured product, by using a specific acidic curing agent in the production of the titled molded article by impregnating and curing a resol-type liquid phenolic resin in fibers in the presence of an acidic curing agent. CONSTITUTION:The objective molded article can be produced by compounding 100pts.wt. of a resol-type liquid phenolic resin with preferably 5-30pts.wt. of an aryl acid phosphate of formula I and/or II (R is 1-9C alkyl; n is 0-3) (produced by the reaction of a phenolic compound with phosphoric anhydride) and impregnating and curing the mixture in fibers. The resin can be cured at normal or medium temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a fiber-reinforced phenolic resin molded product that cures at normal to medium temperatures and has excellent workability and curability.

[Prior Art] Since phenolic resin has superior flame resistance and heat resistance compared to unsaturated polyester resin, attempts have recently been made to use it in the mya reinforcing matrix in place of unsaturated polyester resin.

Room-temperature/medium-temperature curing fiber-reinforced phenolic resin moldings are usually made by blending liquid resol-type phenolic resin with an acidic curing agent, fillers, flame retardants, molding agents, coloring agents, etc., and impregnating it into fibers. Manufactured by curing while containing moisture volatile matter, the molded product has superior properties compared to commonly reinforced unsaturated polyester resin molded products in terms of flame resistance, low smoke emission, heat resistance, chemical resistance, etc. Has/K to various uses,
For example, it is expected to be used in various applications such as tact, ceilings, corrosion-resistant pipes, aircraft parts, vehicle parts, and shelters.

However, when a generally known organic acid or inorganic acid is used as an acidic curing agent for liquid resolyaphenol resin, the balance between workability and curing properties is poor and it is not practical.

For example, common acidic curing agents include WL acid, hydrochloric acid,
Strong acids such as phosphoric acid, organic strong acids such as para-toluenesulfonic acid, xylene sulfonic acid, benzenesulfonic acid, phenolsulfonic acid, and sulfonated phenolic resin are well known.

However, even when a strong inorganic acid such as phosphoric acid or sulfuric acid is added as a hardening agent to liquid resol type phenolic resin to give an appropriate pot life (20 to 60 minutes), emulsification and thickening are fast. Hardening after impregnation is difficult, and if the amount of pressure is increased to speed up curing, emulsification and thickening will be faster, accompanied by rapid heat generation, resulting in shorter pot life and poorer workability and impregnability. In addition, if the mechanical strength of the obtained molded product is low, use a strong organic acid such as para-toluenesulfonic acid, phenolsulfonic acid, or sulfonated phenol resin as a curing agent to ensure an appropriate pot life (20 to 60 minutes). When blended with liquid resol type phenolic resin, the initial thickening is slightly suppressed compared to strong inorganic acids, but curing after fiber impregnation is slow;
When the amount of organic strong TV clay is increased, the setting increases rapidly and generates rapid heat generation, and the pot life becomes too short, resulting in poor workability and impregnability, and the resulting molded product has disadvantages such as low mechanical strength.

On the other hand, some attempts have been made to use a combination of an a-acid and an inorganic acid, for example, a combination of a sulfonated phenol resin and phosphoric acid (see JP-A No. 57-102929). When blended with liquid resol resin, emulsification occurs within a short time after blending, possibly due to the use of phosphoric acid, resulting in heat generation, thickening, and problems with workability, impregnability, curing hue, corrosion resistance, etc. The mechanical strength of the molded product is also low.

[Problems to be solved by the invention] Therefore, the present inventors conducted extensive research to improve the above-mentioned drawbacks such as mechanical strength, workability, impregnability, curing color, and corrosion resistance. By incorporating a curing agent, emulsification is delayed, viscosity is reduced, and an appropriate pot life is obtained, and the product can be cured at room temperature or medium temperature after impregnating the fibers.
The present invention was completed based on the discovery that a fiber-reinforced material with excellent cured color, excellent corrosion resistance, and high mechanical strength could be obtained.

[Means for Solving the Problems] That is, the present invention provides a method for manufacturing a fiber-reinforced phenolic resin molded article by impregnating and curing a liquid resol type phenolic resin in the presence of an acidic curing agent. However, R is an alkyl group having 1 to 9 carbon atoms, and n is 0
or an integer from 1 to 3] is used as an acidic curing agent.

[Function] The liquid resol type phenolic resin used in the present invention is a liquid resol type phenolic resin obtained by reacting 1 mole of phenols and 0.3 to 3.0 moles of aldehydes in the presence of an alkaline catalyst. It is an initial condensate. This initial condensate may be partially neutralized with an acid, or may be dehydrated and the water replaced with an appropriate solvent. Examples of phenols include phenol and its homologs such as cresol, xylenol, and alkylphenol. can give. Examples of aldehydes include formaldehyde, acetaldehyde, and furfural.

The allyl acid phosphate used as the acidic curing agent of the present invention has the general formula [I] and/or [111
It is a compound represented by is phenol 3
Formulas [I] and [111] are produced by adding 1 mole of phosphoric anhydride dropwise to 42 to 45 °C, heating to 120 °C after one drop, and stirring at the same temperature for 2 to 3 hours. Mixtures are preferably used.

Raw obtained with this method! &, the product contains -・In addition to containing 45 to 50% of each of the general formulas [I] and [11], it also contains a dimer represented by the general formula % [where R and n are the same as above]. The allyl acid phosphates of the invention may also contain small amounts (less than 5%) of free phenol, which do not interfere with the use of the allyl acid phosphates of the invention; However, if free phenol increases, allyl acid phosphate itself will crystallize and solidify, and if used as is, curing will be slow, which is undesirable. The amount of the mixture represented by formulas [I] and [■] is 90%, preferably 95%.
% or more is desirable.

1 to 50 parts by weight of the allyl acid phosphorescent resol type phenolic resin of the present invention to obtain workability, pot life and curing time suitable for molding of various plastics at room temperature to medium temperature. Parts by weight preferably 5-30
Used in parts by weight range.

The various plastic molding methods listed here include the well-known hand-lay attach method, spray-up method, preform mated tie method, cold breath method, resin injection method, vacuum bag method, filament winding method, pultrusion method, etc. can be mentioned. The molding temperature may vary depending on the amount of curing agent, curing cycle, and molding method, but it can be arbitrarily selected from room temperature to 90°C, and if necessary, post-curing can be performed at 60°C to 120°C.

Examples of the #a fiber reinforcing agent used in the present invention include glass fibers such as glass chopped strand mat, glass chopped, glass cloth, glass roving, continuous mat, foam mat, and surf ace mat, carbon fibers, whiskers, etc. Examples include right-sided fibers such as aramid fibers and aramid fibers.

The amount of pepper is preferably 20 to 60%. Fiber compensation decreases, and 9s flammability also decreases. If the content of the fiber reinforcing layer exceeds 70% by weight, the impregnability will be poor and the surface condition will also be poor.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Hardness was measured using the Barcol 934 method, and pH was measured using a glass electrode.

Examples 1 to 2, Comparative Examples 1 to 4 According to the formulation shown in Table 1, liquid resol type phenolic resin for fiber reinforcement (mixed for 1 minute in a Showa Kobunshi car, in an atmosphere at a temperature of 25 ° C. Table 1 shows the values obtained by measuring the emulsification time and hardening time.

FRP molding is done by blending various acidic curing agents with liquid resol type phenolic resin using the mixing method shown in Table 1.
After mixing for 1 minute, using a 450 g/m" glass chopped strand mat (3 plies), the hend lay-up molding method was used to mold the strands to a thickness of 3 ply on a glass plate covered with a Mylar film.
1. A flat plate containing 30% glass was molded.

The physical properties of the obtained fiber-reinforced phenol molded product are shown in the same table.

[Effects of the Invention] As is clear from the results in Table 1, according to the M method of the present invention, emulsification after blending is slow and there is no initial viscosity increase, resulting in good workability and rapid hardening. The cured product is light in color and has good corrosion resistance.

The resulting fiber-reinforced molded product has corrosion resistance, 41! Because of its good mechanical strength, it is used where metals, water, etc. are used.

Claims (1)

[Claims] In a method for manufacturing fiber-reinforced phenolic resin molded products by impregnating and curing fibers with liquid resol type phenolic resin in the presence of an acidic curing agent, there are general formulas, mathematical formulas, chemical formulas, tables, etc. ▼[I] and/or ▲Mathematical formulas, chemical formulas, tables, etc.▼[II] [However, R is an alkyl group having 1 to 9 carbon atoms, and n is 0
or an integer from 1 to 3] is used as an acidic curing agent.