JPS62230829A - Molding material - Google Patents

Abstract

PURPOSE:To provide a molding material composed of a thermoplastic resin and a carbon fiber material coated with polyvinyl pyrrolidone and having excellent adhesivity between the carbon fiber and the resin, excellent impact resistance and electrical conductivity. CONSTITUTION:The objective molding material is composed of (A) carbon fiber produced by activating the surface of carbon fiber preferably by the treatment with potassium permanganate or nitric acid or the electrolytic treatment in an electrolyte solution, passing the surface-treated fiber through a solution obtained by dissolving polyvinyl pyrrolidone having a molecular weight of 10,000-360,000 in water, methanol, etc., at an amount of 0.5-10(wt)%, removing the solvent with infrared lamp, hot air, etc., and optionally cutting to 1-10mm long (the amount of polyvinyl pyrrolidone attached to the fiber is 1-10%) and (B) a thermoplastic resin. The molding material is preferably mixed and pelletized before molding.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding material made of a carbon fiber material whose surface is coated with polyvinylpyrrolidone (hereinafter abbreviated as "PvP") and a thermoplastic resin. An object of the present invention is to provide a molding material that can improve the mechanical properties of carbon fiber reinforced resin (hereinafter referred to as "CFRPJ"), particularly the strength and impact strength, as well as the electrical properties of CFRP.

Carbon-N fiber has excellent elastic modulus, abrasion resistance, electrical properties, chemical resistance, and light weight, but carbon fiber is rarely used alone, and is used as a reinforcing material for resins, metals, etc. It is common. In particular, it is used in the aerospace industry as a reinforcing material for resins.
Widely used in the leisure industry. However, the surface of this carbon fiber is essentially inactive, and its adhesion to resin cannot be said to be good.

Improving the adhesion between carbon fibers and resin to improve the mechanical properties of CFRP is an important factor in improving the reinforcing effect of carbon fibers.

Poor adhesion between carbon fibers, especially short fibers, and thermoplastic resins results in a decrease in the impact strength of carbon fiber-reinforced thermoplastic resins. In other words, when m impact force is applied to a carbon fiber-reinforced thermoplastic resin whose adhesion between the carbon fiber and the resin has not been improved, shearing and peeling phenomena easily occur at the interface between the carbon fiber and the resin, resulting in cracks. This is the point of occurrence, and the tIjJ impact strength is significantly lower than in the case of thermoplastic resin alone.

This low impact strength of carbon fiber-reinforced thermoplastic resins is a major problem that limits its application fields, even though it has superior properties other than impact strength compared to glass fiber-reinforced thermoplastic resins. This is one of the causes.

As solutions to these problems, it has been proposed to select 41111 and to perform so-called surface activation, in which carbon fibers are treated with an oxidizing agent or treated with electricity in an electrolyte solution. .

However, this surface activation treatment alone is insufficiently effective when using thermoplastic resin as a matrix! 7'
, J.

On the other hand, carbon fiber is known to be electrically conductive;
In the case of CFRP, it is said that if the adhesion between the carbon fiber and the resin is improved and the impact resistance etc. are improved, the electrical conductivity of CFRP will generally decrease.

The present inventors solved these contradictory problems and developed a CF
The present invention was developed as a result of studies on methods for improving the electrical conductivity of RP and also improving its impact resistance.

In other words, the present invention is a molding material made of a carbon fiber material whose surface is coated with 1 to 10% by weight of PVP and a thermoplastic resin. In particular, 1 to 1 carbon fibers that have been surface activated
This is a molding material consisting of a carbon miscellaneous material covered with 0% by weight of PVP and a thermoplastic resin.

The molding material of the present invention has C
It is possible to improve the mechanical properties of FRP, and
CF when using carbon fiber without surface coating with PVP
Compared to RP, the electrical conductivity of CFRP can be significantly improved. As mentioned above, such effects of the present invention are surprising because good adhesiveness between carbon fibers and resins generally leads to a decrease in electrical conductivity.

When the product of the present invention is used, CFRP, which has good adhesion between carbon fibers and resin and good conductivity, is inferior to CFRP, which can be used as an antistatic material and as a heating element. .

For example, Table 1 shows the effects of the present invention on the volume resistivity of CFRP when carbon fibers are subjected to surface activation treatment to increase their impact strength, along with comparative examples.

Table 1 (Note) Carbon fiber @: 12,000 filament strand C
FRP: carbon fiber/nylon 66 = 20/80,
PVP: 3ifi amount% Surface activation: Electrolysis, 30°C, 10% (Nl(-)zSO
, in aqueous solution, current density 0.06 A l2S3 Charpy impact strength: JIS K7111 volume resistivity + ASTM-D 257, applied voltage 10V As is clear from Table 1, as the impact strength of the untreated material increases, the electrical resistance increases. While P
It can be seen that in the case of the VP surface coating, even if the impact strength is increased, the electrical resistance does not increase, and on the contrary, the electrical resistance does not show a tendency to decrease.

Furthermore, a secondary effect of the present invention is that when kneading with a thermoplastic resin using an extruder, the drop in the hopper is extremely excellent and a homogeneous mixture can be easily obtained.

For example, Table 2 shows the results of a mixing test using an extruder after adding PvP to carbon fiber strands instead of scrap. The test in Table 2 was conducted using 2 kg of carbon fiber, which was made by cutting 12,000 filament strands into 6 mm pieces.
Mix 8 kg of nylon 66 and 4% 4 in a ■ type blender.
The carbon fibers were charged at once into the hopper of a screw extruder with 0+e-bend, and the amount of carbon fibers remaining in the small flanges was measured.

Table 2 According to the results, when the PVP coating m becomes 1% or more, the carbon structure residual rate rapidly decreases to 1 to 0%, and therefore, the composition of the m fiber material and resin of the present invention. It can be seen that the material falls into the hopper easily and has excellent mixing properties.

In the present invention, carbon fibers are known carbon 1111i strands and chopped strands obtained from acrylonitrile fibers, rayon, pitch, etc. as raw materials. Also, this carbon 1! Carbon fibers may or may not be surface activated, but carbon fibers that have not been surface activated will have a more significant effect according to the present invention.

Here, as the surface activation treatment, the surface of the carbon fiber is treated with potassium permanganate or nitric acid, or electrolyzed in an electrolyte solution II&! The known surface activation treatment applied to ordinary coal jlIlaN is employed.

PVP as a coating material for carbon fibers is generally commercially available, and those having a molecular weight of 10,000 to 360,000 are used. This PvP is used by being dissolved in water, alcohols such as methanol and ethanol, chloroform, or a mixed solvent of alcohols and acetone.

The method for coating the surface of carbon fibers is to coat PVP with the above solvent.
．． A 5 to 10% by weight solution is prepared, a carbon fiber strand is immersed in the solution, and the solvent is removed using an infrared lamp, hot air, or the like. Then, if necessary, the carbon fiber can be cut to a length of 1 to +Onm to obtain a chopped strand of carbon fiber whose surface is coated with PVP.

In this PvP coating, the amount of PVP deposited must be 1 to 10% by weight. If it is less than 1% by weight, it will not have the desired effect, and will not fall out of the hopper and will reduce workability.

If it is more than 10% by weight, the effect of improving the mechanical properties of CFRP will be insufficient.

The thermoplastic resin in the present invention is a matrix resin, such as polyvinyl chloride, polyethylene, polybutylene terephthalate, polystyrene, polyphenylene sulfide, polyamide, polyacetal, polycarbonate, or a molding thermoplastic resin commonly used with carbon fibers. .

The molding material according to the present invention can be molded by directly feeding it into the hopper of an injection molding machine with a set of screws, but considering the dispersibility of fibers and ease of handling during molding, it is preferable to go through the process of -〇 mixed pellets. is preferred.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 Acrylonitrile fibers having a combination composition of 1% acrylonitrile 97ffI and 3% by weight of methyl acrylate were pre-oxidized and carbonized to form 11 carbon fiber strands (single fiber diameter 7μ, 12,000 filaments).
°C, 10% rall? In ammonium aqueous solution, m flow density 0
．． The surface was activated at 0.06 A/m' for 3 minutes, poured into a 3fflld% methyl alcohol solution of PVP (intermolecular 4xlO''), dried with hot air, and
A strand with a VP adhesion amount of 3.5% by weight (based on the strand) was obtained.

This strand was cut to a fiber length of 61 Ill to obtain a chopped strand. This chopped strand 1k
After mixing 4JL of nylon 66 with 4JL of nylon 66 in a V-type blender, use a 40+N vented extruder and set the cylinder temperature to 260.
A pellet with a diameter of about 3 mm and a length of 61 ml was produced by extrusion at ~290° C. and a screw rotation of r&50 rpm.

Predetermined test pieces were made from this pellet using a 5-ounce injection molding machine, and various properties were measured. The results are shown in Table 3 below.

Example 2 A test piece was made in the same manner as in Example 1, except that the carbon fiber strand used in Example 1 was passed through a PVP methyl alcohol solution and subjected to PVP treatment without surface activation treatment. Table 3 shows the measurement results of various properties of this test piece.

As a comparative example, similar test pieces were made for carbon fibers that were not subjected to PvP surface coating treatment, one with surface activation treatment (a) and one without surface activation treatment (b), and the measurement results are shown in Table 3. Indicated.

However, the tensile strength and tensile modulus are ASTM-D638,
The bending strength and bending modulus were each measured according to ASTM-0790.

Table 3 Example 3 In Example 1, the characteristics measured when molding was performed with different mixing ratios of carbon fiber and matrix resin (nylon 6G) were as shown in No. 4.

Table 4 Example 4 A PVP methanol solution was applied to the surface-activated carbon fiber strands used in Example 1, and 3.5φ amount % of P was applied.
A carbon fiber chopped toss 1-land with VP was used.

The chopped strands and polyacetal were mixed at an ffqfit ratio of 20:80 and molded using an extruder to make predetermined test pieces, and various properties were measured. The results are shown in Table 5. The same table also shows the case where polycarbonate is used instead of polyacetal.

Table 5

Claims (2)

[Claims] (1) A molding material consisting of a carbon fiber material whose surface is coated with 1 to 10% by weight of polyvinylpyrrolidone and a thermoplastic resin. (2) 1 to 10% by weight of surface-activated carbon fiber
The molding material according to claim (1), comprising a carbon fiber material whose surface is coated with polyvinylpyrrolidone and a thermoplastic resin.