KR900003109B1 - Method for preparation of complex materials having high strength - Google Patents

Abstract

In a prepartation of a high-strength composite meterials contg. a aramide fiber used for reinforcing filler, the aramid fiber is dipped into the mixt. solun. of sulphuric acid and nitric acid at 20-30≰C for 10-50min.; then, the fiber is separated and dipped into hot-water at 50-100≰C in presence of H2 gas and separated, dried in order to introduce amino gp. onto the surpace of the aramide fiber; and then 10-60 vol.% of the said-surface treated aramide fiber and 90-40 vol.% of a matrix polymer are mixed. Pref the mixt. of acid soln. comprises 60vol.% sulphuric acid and 40 vol.% nitric acid, and pref. the mixt. of the acids is diluted to 30-50 wt.% w.r.t water soln.

Description

Manufacturing method of high strength composite material

The present invention relates to a method for producing a high strength composite material, and in particular, to a method for producing a high strength composite material using aramid fibers processed as a reinforcing fiber by introducing an amino group on the surface of the aramid fiber to improve interfacial adhesion with the substrate polymer. It is about.

Aramid fiber has a high strength and high elastic modulus, but because of its small specific gravity compared to metal, it is widely used as a reinforcing fiber for high strength composite materials. However, such aramid fibers have a disadvantage that the interfacial adhesion of the substrate polymer is weak because the surface is chemically inert.

Therefore, studies have been conducted to improve the interfacial adhesion with the matrix polymer by modifying the surface of the aramid fibers used as reinforcing materials. For example, Japanese Laid-Open Publication 55-1393 uses aramid fibers as low temperature plasma. The method of modifying the surface by treatment has been introduced, but has not been put into practical use, and the mechanism has not been revealed.

In addition, Japanese Unexamined Patent Application No. 54-28867 discloses a method for treating aramid fibers using a coupling agent treatment method, and Japanese Unexamined Patent Application Nos. 52-128982 and 52-45674 provide various monomers on the surface of aramid fibers. A method of increasing interfacial adhesion with a matrix polymer is described.

However, all of these conventional techniques, as described in US Pat. No. 3,869,430 and the like, polymerize inorganic salts, aromatic diamines, and aromatic dieside chlorides in amide solvents, and then separate, wash, and dry the polymers. A dope is prepared by dissolving in a sulfuric acid solvent of 98% or more, the dope is spun into water to prepare aramid fibers, and the fibers are subjected to surface modification by the above-described methods.

Therefore, in order to manufacture aramid fibers to be used as a reinforcing material, a series of manufacturing processes are complicated, such as separation of the polymer, washing with water, drying and dissolving it in a sulfuric acid solvent and spinning. There was a disadvantage such that the manufacturing equipment is easily corroded.

Therefore, the present invention is to modify the aramid fibers prepared through a much safer and simpler process such as not using sulfuric acid so that the adhesion to the substrate polymer is significantly improved, thus using the surface-modified aramid fibers as a reinforcing material It is an object of the present invention to provide a method for providing a method for producing a composite material.

Hereinafter, the present invention will be described in detail.

According to the present invention, in preparing a high strength composite material, the aramid fibers are immersed in a mixed acid solution of sulfuric acid and nitric acid at a temperature of 20 to 30 ° C. for about 10 to 50 minutes, and then separated from each other again under a hydrogen stream of 50 to 100 ° C. It is characterized in that it is prepared by introducing an amino group on the surface of the aramid fibers by immersion in hot water, washing and drying, then mixing 10 to 60% by volume of the aramid fibers with 90 to 40% by volume of the matrix polymer.

Hereinafter, the present invention will be described in more detail.

When the present invention is roughly classified into processes, it is divided into a process of manufacturing aramid fibers, a process of modifying the surface of the aramid fibers, and a process of manufacturing a high strength composite material using the aramid fibers as reinforcing fibers.

1) Preparation of Aramid Fiber

In order to manufacture the aramid fibers used as reinforcing fibers in the present invention, first, as is known in the art, an inorganic mole, an aromatic diamine, and an aromatic dieside chloride are added in an equimolar amount in an amide solvent, and maintained at a temperature of 10 ° C. or lower. The prepolymer is prepared by stirring until it gels. At this time, the stirring time usually takes about 30 seconds to 10 minutes.

Subsequently, when the prepolymer is spun into a tertiary amine-based solvent through detention, aramid fibers are obtained. Technical details not described in the first step are carried out under the same conditions as those for preparing aramid fibers. .

2) surface modification treatment for the aramid fibers

In order to surface-modify the aramid fibers according to the present invention, sulfuric acid and nitric acid are first mixed in a volume ratio of 60:40, and about 30 to 50% by weight of water is added to the mixed acid, and then the mixed acid solution is added to 20 to The aramid fiber of about 40 to 60% by weight is immersed in the mixed acid solution for about 20 minutes while maintaining the temperature at 30 ° C.

Subsequently, the aramid fibers are separated from the mixed acid solution, immersed in hot water at 50 to 100 ° C. for 15 to 20 minutes under hydrogen stream, and the aramid fibers are separated from the hot water, washed, and dried.

를 공격하여 천전자성 치환방응을 일으키게 되고, 따라서

상태의 π 콤플렉스를 형성하게 된다. 그러나 상기 π 콤플렉스는 그 자체가 매우 불안정하기 때문에 곧

형태의 σ콤플렉스를 형성하게 되고, 상기 σ콤플렉스 역시 불안정하여 다시 안정한 방향족환인

나

를 형성하게 되며, 상기 방향족환들은 H₂에 의해서

로 치환되므로서 아미노기가 형성되게 된다. 즉, 본 발명에 따라 제조되는 보강재료용 아라미드섬유는 그 표면에 아미노기가 도입되도록 하므로서 기질중합체와의 계면접착력을 크게 증대시킨 것이다.In this way, the surface treatment of the aramid fibers according to the present invention is the electron in the aromatic ring in the aramid chain

Attacking and causing a cyclic substitution reaction, thus

Π complex of state is formed. But the π complex is very unstable itself and soon

Form an σ complex, which is also unstable and is a stable aromatic ring.

I

To form the aromatic rings by H ₂

Substituted with, an amino group is formed. That is, the aramid fibers for reinforcing materials produced according to the present invention is to significantly increase the interfacial adhesion with the matrix polymer while allowing the amino group to be introduced to the surface.

3) Fabrication of high strength composite materials

Subsequently, when the aramid fiber for reinforcing material introduced amino group on the surface is mixed with the matrix polymer as described above, it becomes a high strength composite material according to the present invention, wherein the amount of the aramid fiber used as the reinforcing fiber is 10 to 60 vol. %, And the amount of the matrix polymer added is 90 to 40% by volume.

Substrate polymers that may be used in the present invention include epoxy resins and triethylene tetramine or mixed resins thereof.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

Preparation of Aramid Fiber for Reinforcement Material

Sulfuric acid and nitric acid are mixed at a volume ratio of 60:40, and 150 g of the mixed acid is diluted with 60 cc of water and kept at a temperature of 25 ° C., and 100 g of aramid fiber is immersed in the mixed acid solution for about 20 minutes. . Subsequently, the aramid fibers were separated from the mixed acid solution, washed sufficiently with hot water, immersed in hot water at 50 to 100 ° C. again, blown with hydrogen gas for about 15 minutes, and the aramid fibers were separated and washed with hot water again. When dried at a temperature of 60 ° C. for about 1 hour, aramid fibers for reinforcing materials having amino groups introduced thereon are obtained.

Example 2

Fabrication of High Strength Composites

Mix the aramid fibers for the reinforcing material obtained in Example 1 with a mixed resin of epoxy resin and triethylene tetramine, but mixed the aramid fibers by 10, 20, 30, 40, 50, 60% by volume, and hot press ( Hot press) is pressurized to a temperature of 150 ℃ and pressure of 150Kg / ㎠ to prepare a high-strength composite material of the plate type.

[Comparative Example]

The same procedure as in Example 2 was carried out except that aramid fibers having no amino group introduced therein were used as reinforcing fibers.

Tensile strength was measured in the vertical direction (90%) and the parallel direction (0 °) with respect to the direction of the reinforcing fibers, respectively, for the composite material prepared according to the above Examples and Comparative Examples, and the results are shown in Table 1 below. .

TABLE 1

As can be seen in Table 1, the high strength composite material prepared according to the present invention can be seen that its tensile strength is increased by about 30% compared to the composite material prepared by the conventional method.

Claims (3)

In preparing a high strength composite material containing aramid fibers as a reinforcing fiber, the aramid fibers are immersed in a mixed acid solution of sulfuric acid and nitric acid at a temperature of 20 to 30 ° C. for 10 to 50 minutes, and the aramid fibers are separated again. Distilled in hot water at 50 to 100 ° C. under a hydrogen stream, and separated, washed and dried to introduce amino groups on the surface of the aramid fibers, and then 10 to 60% by volume of the surface treated aramid fibers and 90 to 40% of the substrate polymer. A method for producing a high strength composite material, characterized in that by mixing the%. The method of claim 1, wherein the mixed acid solution is mixed with sulfuric acid and nitric acid in a volume ratio of 60 to 40, and the mixed acid is diluted with about 30 to 50% by weight of water. The method of claim 1, wherein the matrix polymer is an epoxy resin, triethylamine, or a mixed resin thereof.