JP3222513B2 - Method for producing bundled short carbon fiber for polycarbonate resin reinforcement, polycarbonate resin and carbon fiber reinforced polycarbonate resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short carbon fiber bundle used for reinforcing a thermoplastic resin.

[0002]

2. Description of the Related Art In recent years, a fiber-reinforced molding material obtained by mixing and dispersing carbon fibers in various matrices has excellent properties such as high strength, high rigidity, low specific gravity, high electric conductivity, and low thermal expansion. Due to its high efficiency and high wear resistance, it is expected to be used in a wide range of applications, and is attracting attention as an industrially important material.

[0003] In general, when a short carbon fiber is mixed and dispersed in various matrices to obtain a fiber-reinforced molding material, in order to facilitate handling of the short carbon fiber and enhance workability in the mixing and dispersion steps, Short carbon fibers in which a large number of carbon fibers are previously bundled with a sizing agent are used. As such a sizing agent, epoxy, nylon, modified polyether resin and the like are usually used. However, in the short carbon fiber bundled with the conventional sizing agent,
There are various problems in the process of mixing and dispersing the fibers into the matrix resin due to insufficient convergence of the fibers. For example, pills of short carbon fibers are formed in the feeder and clogging occurs in the feed process, or It has disadvantages such as the inability to uniformly disperse the fibers in the matrix.

[0004] For this reason, improvement in mechanical properties and the like expected by blending of carbon fibers is not recognized. In order to solve these problems, diisocyanate and geo-
In the reaction of 0.95 ≦ NCO / OH ≦ 1.0, and 0.3 to 0.3% of a completely thermoplastic linear polyurethane resin.
A device such as using carbon fiber coated at 10% by weight has been proposed (Japanese Patent Publication No. 1-46636).

[0005] However, although the mechanical reinforcement effect is excellent, the improvement in conductivity is not sufficient.

[0006]

SUMMARY OF THE INVENTION The present invention provides a reinforced short carbon fiber for resin reinforcement which improves workability in a dispersing step, handleability in high-temperature work, and simultaneously satisfies mechanical properties and conductivity. Is what you do.

[0007]

[Means for Solving the Problems] That is, the present invention provides:
Fiber length of 0.3 to 10% by weight of polyurethane resin crosslinked with block isocyanate
It is a bundled short carbon fiber of １２12 mm. Hereinafter, the present invention will be described in detail.

In the present invention, a polyurethane resin is used as a sizing agent. The polyurethane is not particularly limited, and at least one of polyisocyanates having two or more isocyanate groups in the molecule and two or more in the molecule.
Known products obtained by reacting at least one kind of polyols having at least two hydroxyl groups can be used. Examples of the polyisocyanates include the following.
1,6-hexanediisocyanate, 4,4'-diphenylmethanediisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate 4,4'-dicyclohexylmethane diisocyanate, 4,4'-hydroxydiisocyanate, isophorone diisocyanate, 1,5-naphthalenediisocyanate, 4,4-diphenyldiisocyanate, Phenylene 1,4-diisocyanate, phenylene 2,6-diisocyanate, 1,3,6-hexamethylene triisocyanate and the like.

The following are exemplified as polyols. Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, polycarbonate -Glycols having two alcoholic hydroxyl groups, such as -boneditol, neopentyl glycol, alkylene oxide adducts of bisphenols and alkylene oxide adducts of hydrogenated bisphenols; Polyethylene glyco-
, Polyproprenglycol, polyoxytetramethylene glycol, etc., polyetherdiols, polyethylene adipate, polypropylene adipate, polybutylene adipate, polytetramethylene adipate To
Polyesterdiols such as polypentamethylene adipate, polyhexamethylene adipate, polycaprolactone diol, alcohols such as trimethylolethane, trimethylolpropane, glycerin, pentaethsitol and the like. Multivalent alcohol having three or more hydroxyl groups
And the like.

As the isocyanate of the block isocyanate of the present invention, the above-mentioned isocyanates can be used. As blocking agents, alcohols, phenols, ε-caprolactam, oximes, active methylenes, mercaptans, amines, imides, acid amides, imidazoles, ureas, carbamates ,
Imines and sulfites are used.

The blending amount of the block isocyanate is preferably such that the NCO group and the urethane group of the block isocyanate are equivalent to each other. Therefore, the polyurethane crosslinked with the block isocyanate has an NCO / OH> No. 1 so-called polyurethane. The sizing agent used in the present invention has a strong convergence of carbon fibers, is smoothly fed during kneading with a resin having high heat resistance, and does not cause clogging during the working process.

Further, by using a block isocyanate as a crosslinking agent for urethane, a sizing agent for an aqueous emulsion can be used, and there is no need to recover a solvent as compared with a solvent-based one, so that it is economical and has no danger. Further, there is an advantage that there is no pollution with respect to environmental problems. In order to further promote the crosslinking reaction, it is also preferable to use a catalyst.For example, triethylamine, triethylenediamine, tin octylate, dibutyltin dilaurate, 1,3-diacetoxytetrabutylstannoxane and the like are added to the emulsion solution. May be.

In order to obtain the short carbon fiber of the present invention, first, a roving of carbon fiber is brought into contact with or dipped in a solution obtained by mixing an aqueous emulsion of polyurethane and an aqueous emulsion of blocked isocyanate. For example, heat treatment is performed by means of hot air drying, infrared drying, microwave drying, or the like, and the polyurethane coated on the surface of the carbon fiber is cross-linked with block isocyanate to form a thermosetting polyurethane. I do.

The coating amount of the sizing agent of the present invention needs to be in the range of 0.2 to 10% by weight based on the weight of carbon fibers. If the amount is less than 0.2% by weight, the effects of the present invention will not be sufficiently exhibited, and if it exceeds 10% by weight, the mechanical properties and heat resistance of the obtained chip tend to decrease. Particularly preferred coating amounts are in the range of 0.3 to 8% by weight.

In the present invention, the carbon fiber used as the material is not particularly limited, and various known carbon fibers,
For example, arbitrarily selected from rayon, polyacrylonitrile, pitch, lignin, carbonaceous fiber and graphite fiber produced using a hydrocarbon gas and the like, and metal-coated carbon fiber obtained by coating a metal on these. Can be used. Preferably, carbon fibers or graphitic fibers obtained from polyacrylonitrile are used.

It is an object of the present invention to provide a short carbon fiber bundle in this way, but other fillers used in fiber-reinforced molding materials, such as glass fiber, aramid fiber, silicon carbide fiber, metal The present invention can be applied to fibers, boron fibers, and the like. In order to produce a fiber-reinforced molding material using the bundled short carbon fibers of the present invention, a known method for producing a glass fiber-reinforced molding material can be applied. For example, a carbon fiber reinforced molding material can be manufactured by melt-kneading a bundle of short carbon fibers and a matrix resin using an extruder. The molding material may be a filler other than the short carbon fiber bundle, for example, a fiber reinforced material such as glass fiber or aramid fiber, or a powdered or flexible material such as glass, calcium carbonate, metal oxide, or carbon black.ク -shaped additives and the like may be contained as necessary.

The matrix resin used for the carbon fiber reinforced molding material is generally commercially available polycarbonate, polyamide, polyphenylene ether, polyoxymethylene, polyester, polyphenylene sulfide, polyolefin, ABS resin. , Polyether, ether ketone, polyimide, polysulfone,
Known matrices such as polymers such as polyethersulfone, polyurethane, phenolic resin, and epoxy resin, or copolymers thereof, may be used. Particularly, in the case of polycarbonate resin, the mechanical properties and conductivity of the molded product are remarkably improved. Further, since the sizing agent used in the present invention does not decrease the molecular weight of the polycarbonate, it has the advantages that the physical properties do not decrease and that the sizing agent can be recycled.

Polycarbonate resin is a conventional polycarbonate resin.
This is a method similar to the method for producing a carbonate resin, that is, a method comprising reacting an aromatic dihydroxy compound with phosgene or a carbonic acid diester. In this case, as the aromatic dihydroxy compound, 2,2-bis (4-hydroxyphenyl)
Propane (generic name bisphenol A), tetramethylbisphenol A, tetraethylbisphenol A, tetrabromobisphenol A, bis (4-hydroxyphenyl) methane, 1,1-bis (4- (Hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl)
Propane, 1,1-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxy -3-methylphenyl) propane, 2,2-bis (3,5-dibromo-
4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone and the like.

Particularly preferred polycarbonate resins are
2,2-bis (4-hydroxyphenyl) alkane-based,
In particular, it is a polycarbonate containing bisphenol A as a main component. Average molecular weight 15,000-100,000
Are preferred. The measurement method used in the example is shown. (1) The mechanical properties of the fiber-reinforced molding material are in accordance with JIS K6
810 was measured. (2) The conductivity of the fiber-reinforced molding material is 50
cut out to a size of 90 mm x 90 mm x 2.5 mm.
The strike was applied on two parallel sides of a square having a side of 50 mm, and the electrical resistance between them was defined as the surface resistivity (Ω). (3) The molecular weight of the polycarbonate resin was determined by gel permeation chromatography (Tososo HLC8020) and column (Tososo TSK-GEL (G4000HxL, G5000Hx).
L was measured at 40 ° C. and the solvent was THF, and the molecular weight was calculated as the weight average value from the polystyrene conversion value.

[0020]

Example 1 Acrylonitrile carbon fiber (Hi-Carbon 12kf, manufactured by Shin-Asahi Kasei Carbon Fiber Co., Ltd.)
To 100 parts by weight of an aqueous polyurethane emulsion (KP-2807 manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.) and an aqueous emulsion of block isocyanate (Matsumoto Yushi Pharmaceutical Co., Ltd.)
CAT-11) 15 parts by weight, and immersed in a solution having a solid concentration of 4% by weight, and 4% by weight based on carbon fibers
Adhere and dry with hot air at 180 ° C. for 5 minutes.

The bunched carbon fiber thus obtained was cut into a length of 6 mm to produce a bunched carbon short fiber, followed by heat treatment at 160 ° C. for 2 hours to crosslink the polyurethane compound. The obtained bundle of short carbon fibers was soxhed with a solvent of methyl ethyl ketone and dimethylacetamide.
Extraction was performed for 1 hour, and the chops after drying were observed. As a result, it was confirmed that the chops were firmly focused and crosslinked as before the extraction.

To 30 parts by weight of the obtained bundle of short carbon fibers,
70 parts by weight of a bisphenol A type polycarbonate resin was added and dry blended with a V-type blender. This dry blend was kneaded and extruded with a twin-screw extruder equipped with a screw feeder. The strand was not cut even after continuous 10 hours of operation, and the extrusion rate (15 kg / hr) was constant. The obtained strand was pelletized to obtain a fiber-reinforced molding material. Next, a test piece for evaluation was obtained with a Toshiba IS75E injection molding machine, and the bending strength, the bending elastic modulus, and the conductivity were measured. The results are shown in Table 1.

[0023]

Example 2 The procedure of Example 1 was repeated except that 0.6% by weight of a curing accelerator (CAT-64, manufactured by Matsumoto Yushi Co., Ltd.) was added to the emulsion solution of the polyurethane emulsion and the crosslinking agent in Example 1. Table 1 shows the results.

[0024]

Comparative Example 1 A bundle of short carbon fibers was obtained in the same manner as in Example 1 except for the block isocyanate in Example 1. Table 1 shows the results. In the extrusion process,
Extrusion was stable for about 2 hours without strand breaks, but after that, poor extruding in the extruder hopper occurred and continued troubles such as strand breaks. A lump of chop sticking to the-part was observed.

The pellets obtained in the first hour or so were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0026]

Comparative Example 2 Example 1 was the same as Example 1 except that only the epoxy resin was used instead of the polyurethane resin. Table 1 shows the results. In addition, continuous operation was not possible in the extrusion process.

[0027]

Comparative Example 3 Comparative Example 2 was the same as Comparative Example 2 except that 5% by weight of hexamethylenediamine was added to 100% by weight of the epoxy resin. Table 1 shows the results.

[0028]

Example 3 The procedure of Example 1 was repeated, except that 0.3% by weight of a polyurethane resin was coated on carbon fibers. Table 2 shows the results.

[0029]

Example 4 The procedure of Example 1 was repeated except that 8.0% by weight of a polyurethane resin was coated on the carbon fiber. Table 2 shows the results.

[0030]

Comparative Example 4 The procedure of Example 1 was repeated, except that the polyurethane resin was coated with 0.1% by weight of carbon fiber. Table 2 shows the results. In the extrusion process, continuous operation could not be performed.

[0031]

Comparative Example 5 The procedure of Example 1 was repeated, except that the polyurethane resin was coated with 11.0% by weight of carbon fiber.
Table 2 shows the results.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

According to the sizing of the present invention, since the sizing property is excellent, the workability at high temperatures is good, and the mechanical properties and conductivity are particularly improved. Aqueous emulsion sizing agent can be used,
Compared to the solvent system, it is economical, has no danger, and has high industrial value such as no pollution against environmental problems.

Claims (3)

(57) [Claims] As claimed in claim 1 block sizing agent 0.2 to 10% by weight polyurethane resin crosslinked with an isocyanate
A short carbon fiber bundle for reinforcing polycarbonate resin . 2. Polycarbonate and block isocyanate
Sized with polyurethane resin cross-linked with nate
Polycarbonate tree consisting of short carbon fibers
Fat. 3. A polyurethane aqueous emulsion and a block.
To a solution mixed with aqueous isocyanate emulsion
After contacting or dipping carbon fiber, heat treatment
Block the polyurethane coated on the carbon fiber surface
Short bundled carbon fibers crosslinked with isocyanate
Carbon fiber reinforced polycarbonate melt-kneaded with a carbonate resin
Method of manufacturing a resin.