JPH0364522A - Carbon yarn - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improved carbon fibers for use in thermoplastic resin reinforcement.

[Prior Art] Carbon fiber has superior elasticity, wear resistance, and light weight compared to glass fiber, and is used as a reinforcing material for resins. Especially polyphenylene sulfide, aromatic polysulfone,
When used as a reinforcing material in highly heat-resistant engineering plastics such as polyetherimide and aromatic polyetherketone, it improves mechanical strength, critical PV value, and abrasion resistance, making it an excellent material for automobile parts and mechanical parts. It can be.

Traditionally, carbon fibers are often used in carbon fiber reinforced plastics that use 7-trix epoxy resin.
Epoxy resin is used as a binding agent for carbon fibers. Carbon fiber coated with this epoxy resin binding agent is effective when the matrix is a thermosetting resin such as epoxy resin, but it has poor adhesion to highly heat-resistant engineering resins and has a high molding temperature. Since the epoxy resin binder is thermally decomposed, a resin composition with good mechanical strength cannot be obtained.

For this reason, attempts have been made to use polyamide resin as a sizing agent for thermoplastic resins, as seen in JP-A-53-106752.

However, since the molding temperature of these heat-resistant resins requires a high temperature of 350°C or higher, when carbon fibers bound with epoxy resin or polyamide resin are used, the binding agent thermally decomposes during molding. This causes problems such as the formation of hoids and a decrease in the strength of the weld portion.

[Problem that the invention seeks to solve]

The object of the present invention is to improve carbon fibers for use in reinforcing high heat resistant engineering resins.

[Means to solve the problem]

The present inventors conducted various studies to achieve the above object, and found that it is effective to use carbon fiber whose surface is coated with polyetherimide resin as a sizing agent and then heat-treated at 300 to 400°C. This discovery led to the completion of the present invention.

That is, the present invention is a carbon fiber whose surface is coated with polyetherimide resin and then heat-treated at 300 to 400''C.

In the present invention, the polyetherimide resin used as a sizing agent to coat the surface of carbon fibers is a linear polymer having imide bonds and ether bond units, and has the following structural formula, for example: In Japan,
It is commercially available under the trademark "Ultem" from Engineering Plastics Co., Ltd.

Further, the carbon fibers used in the present invention include acrylic, rayon, lignin, pitch, etc., and any of them can be used. In the present invention, acrylic fibers having the highest fiber strength are most preferably used. The carbon fiber may be in any form such as chopped strand, roving, or woven fabric. It is more preferable that the surface of these carbon fibers be oxidized in advance.

The method for coating these carbon fibers with polyetherimide is to soak the carbon fibers in a solution of polyetherimide resin dissolved in a solvent such as methylene chloride or N-methylpyrrolidone, then dry it to remove the solvent. Carbon fibers coated with etherimide resin are obtained.

Usually, the amount of polyetherimide resin coated on the carbon fiber is preferably 0.1 to 10 parts by weight per 100 parts by weight of the carbon fiber, and the effect of the present invention cannot be obtained if it is less than 0.1 part by weight.
Further, even if 10 parts by weight or more is coated, no improvement in mechanical strength can be expected and it is meaningless. The carbon fiber coated with polyetherimide resin as described above is heat treated in air at
It is carried out by exposing to a temperature of 400°C, particularly preferably 340 to 380°C. Heat treatment time is 3-20
The time period is particularly preferably 5 to 15 hours.

Various methods can be employed to mix the carbon fiber coated with the polyether oxide resin and the highly heat-resistant engineering resin. For example, coated and heat-treated carbon fibers can be cut into lengths of 3 to 6 fflI11, and this and a highly heat-resistant engineering resin can be individually fed into a melt extruder and mixed, or a Henschel mixer, Super 5 It is also possible to pre-blend the mixture using a mixer such as a mixer or ribbon blender and then supply it to the melt extruder.

Furthermore, the coated and heat-treated carbon fiber roving can also be directly fed to a melt extruder and mixed with a heat-resistant resin.

Resin 11Ji of the above-mentioned improved carbon fiber and high heat-resistant engineering resin of the present invention! The product can be molded into a predetermined molded product using known molding methods such as injection molding, extrusion molding, transfer molding, and compression molding.

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 Ultem 1000 (trademark) manufactured by Engineering Plastics Co., Ltd. was used as a polyetherimide resin
A 5% by weight polyniethertomide resin solution was prepared by dissolving it in methylpyrrolidone. A roving of acrylic carbon fiber (manufactured by Toho Rayon Co., Ltd., trade name: HTA) whose surface has been acid-treated is continuously immersed in a polyetherimide resin solution.
After drying and removing the solvent, it was cut into 3-inch lengths to obtain chopped strands.

At this time, the amount of polyetherimide resin attached to the carbon fibers was 5%.

This carbon fiber chopped strand was placed in a stainless steel hat, placed in an electric furnace heated to 350°C, and heat-treated in an air atmosphere for 10 hours.

30wt% of the carbon fiber chopped strands obtained in this way and I
CI polyetheretherketone resin PEEK 3
After tri-blending 70 iyt% of 80G (trade name), extrusion was performed using a 40 mm diameter extruder while melt-kneading at an extrusion temperature of 380°C to obtain a uniformly blended pellet.

Next, the above uniformly mixed pellet was molded using a normal injection molding machine at a cylinder temperature of 380°C and a mold temperature of 180°C.
A Danher specimen was prepared under the temperature conditions of
The tensile strength was measured at 2460 kg/min.
It was c-pickled.

Comparative Example 2 In place of the carbon fiber chopped strands coated with polyetherimide resin and heat treated in Example 1, acrylic carbon fibers bound with epoxy resin (manufactured by Toho Rayon Co., Ltd., trade name HT A) were used. A Danher piece of carbon fiber-filled polyetheretherketone resin was prepared by testing in the same manner as in Example 1. Tensile speed 5 mm/
When the tensile strength was measured using cal, it was 1910 kg/c [
Met.

Comparative Example 3 The chopped carbon fiber strand coated with the polyetherimide resin obtained in Example 1 was placed in an electric furnace heated to 260° C. and heat-treated in an air atmosphere for 10 hours.

The carbon fiber chopped strand 30wt% obtained in this way and IC as a high heat resistant engineering authority
Polyetheretherketone resin PEEK 38 manufactured by Company I
After tri-blending 70 wt% of 0G (trade name), extrusion was performed using a 40 nvn diameter extruder at an extrusion temperature of 380°C while melt-kneading to obtain a uniformly blended pellet.

Next, the above uniformly mixed balls 1 to 1 are molded using a normal injection molding machine at a cylinder temperature of 380°C and a mold temperature of 180°C.
Danher specimens were prepared under the temperature conditions of 5mm
The tensile strength was measured at 1940kg/min.
It was c-bo.

Comparative Example 4 Carbon fiber chopped strands coated with polyetherimide resin were placed in an electric furnace heated to 460°C and heat treated in an air atmosphere for 10 hours, but obtained in the same manner as Comparative Example 3. When the dumbbell one-sided tensile strength was measured, it was 2110 kg/cJ.

Example 2 30wt% of chopped carbon fiber strands coated with the polyetheroid resin obtained in Example 1 and heat treated and 70et of polyetherketone resin PEK220P (trade name) manufactured by ICI as a highly heat-resistant engineering resin.
% was tri-blended and then extruded using a 40 mm diameter extruder while melt kneading at an extrusion temperature of 390° C.7 to obtain a uniform pellet.

Next, a Danher test piece was made from the above homogeneously mixed pellets using a normal injection molding machine at a cylinder temperature of 420°C and a mold temperature of 200°C.
When the tensile strength was measured at min, it was 2880 kg /
It was c-bo.

Comparative Example 5 In place of the chopped carbon fiber strands coated with polyether oxide resin and heat treated in Example 2, acrylic carbon fibers bound with epoxy resin (manufactured by Toho Rayon Co., Ltd., trade name HTA) were used. A Danher piece of carbon fiber-filled polyetherketone resin was prepared by testing in the same manner as in Example 2. The tensile strength was measured at a tensile speed of 5 mm/min and found to be 2430 kg/-.

〔Effect of the invention〕

The improved carbon fiber according to the present invention can significantly improve mechanical strength by filling it into a highly heat-resistant engineering resin.

Claims (1)

[Claims] After coating the surface with polyetherimide resin, 300
Carbon fiber heat-treated at ~400°C.