JPH02175943A - Carbon fiber cord - Google Patents

Abstract

PURPOSE:To provide a carbon fiber cord having a specific strength contribution degree and giving belts having high strengths and low elongations by coating carbon fibers with a thermoplastic polyurethane resin. CONSTITUTION:A carbon fiber strand (preferably comprising acrylic based carbon fibers containing >=93wt.% of carbon and 1-7wt.% of nitrogen) having a single fiber number of 1000-15000 and having 50-800 tex is subjected to a fiber surface-oxidation process, dried and subsequently twisted (preferably at the first twisting number of 30-150 turns/m). Two or more of the first twisted carbon fiber strands are doubled, subjected to the reverse twist process (preferably at the second twisting number of 30-150 turns/m) and subsequently coated with a thermoplastic polyurethane resin to provide a carbon fiber cord having a strength distribution coefficient T of >=55% represented by the formula [a is a strength (kg) of the carbon fiber cord measured according to JIS-R 7601 after the resin is removed; and b is a strength (kg) of the carbon fiber cord] and further having a diameter of 1.35mm and a strength of >=200kg.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a carbon fiber cord suitably used as a reinforcing material for a belt. Using this carbon fiber cord, it is possible to make belts with high strength and low elongation.

[Conventional technology and requests]

Conventionally, carbon fiber cords have been produced by adhering various resins such as epoxy resins, polyurethane resins, resorcinol-formalin latex, etc. to carbon fibers, and using various matrix resins and rubbers such as polyurethane resins, etc.
Attempts have been made to use it as a reinforcing material for bells or as a single lobe in combination with rubbers such as styrene-butadiene-based, nitrile-based, and chloroprene-based rubbers. However, these robes cannot withstand high loads,
They often have to be cut, and are often not put to practical use.

This is because the strength of the carbon fibers used is not reflected in the cord strength, and even if a cord is made using a high-strength carbon fiber bundle, the cord strength will be less than the strength of the original carbon fiber. One of the reasons was that the contribution rate was as low as 30-40%.

By the way, carbon fiber cords have lower elongation than the aramid fiber cords currently in use, and do not stretch during use, making them suitable as belt reinforcing fibers. Since the strength is low, there has been a need for a carbon fiber cord that has a strength as high as 11 minutes and maintains this strength during use.

(Objective and Structure of the Invention) In order to meet such demands, the present invention provides a strength contribution ratio, that is, a ratio of cord strength to carbon fiber strength of −[
- It is intended to provide a carbon fiber cord with a high carbon fiber cord.

The present invention is as follows.

(1) A carbon fiber cord having a strength contribution rate (T) of 55% or more as expressed by the following formula (1) and coated with a thermoplastic polyurethane resin.

T (%) −−x 10(1・・・・・・・・・・・・
... (1) r: Strength contribution rate a: After removing resin from carbon fiber cord, JIS-R
Strength (kg) measured in 7G01 b: Strength of carbon fiber cord (k
The number of twists is 30 to 15, which is made by plying two or more m carbon fiber bundles.
The carbon fiber cord according to claim 1, which has 0 pieces/I.

(3) The diameter is 1.3! Below loom, the power is 200k
The carbon fiber cord according to claim 1, which has a carbon fiber cord of at least g.

(4) The carbon fiber cord according to claim 1, wherein the thermoplastic polyurethane resin is contained in an amount of 3 to 20% by weight based on the carbon fiber cord.

In the present invention, carbon fibers are preferably acrylic carbon fibers, containing 93% by weight or more of carbon and 1 to 7% by weight of nitrogen, and the carbon fiber bundle has a structure of 100 L11 fibers.
The fiber bundle consists of 0 to 45,000 fibers and has a weight of 50 to 8,007 tx (grams per 1,000 m of the bundle). The strength of the fiber bundle is preferably 30 after removing the resin from the cord of the present invention as determined by III in JIS-R7601.
0 kgf/mm' or more, more preferably 500 kgf/
+hm' or more.

In addition, in the carbon fiber cord of the present invention, the strength contribution rate of the carbon fiber bundle after resin removal, that is, the ratio of the cord strength to the strength measured according to JIS-Rγ601, is 55% or more. be. If it is less than 55%, it is necessary to use carbon fiber with extremely high strength, which is disadvantageous in terms of efficiency and also tends to cause a decrease in strength during long-term use. As a measure of whether the strength contribution rate is 55% or more in the carbon fiber cord of the present invention, the electrical resistance change rate (R) shown by the following formula (2) can be used. The larger R is, the larger the strong contribution rate is.

-d R (%) = -xloo... (2) R: Electrical resistance change rate C: Carbon 4A! 1 electrical resistance per i-line coat 1111 (
Ω) d: After deresinizing the same carbon fiber cord, it was treated in nitrogen at 450°C to 600°C for 1 to 3 minutes. According to the above, the degree of oxidation on the surface of the carbon fiber is involved in the strength contribution rate, and the strength contribution rate increases depending on the degree of oxidation and the thermoplastic polyurethane resin coating included in the present invention. In particular, when the oxidation is carried out by an electric current electrolytic oxidation method using an aqueous solution of nitric acid or a nitrate, the strong contribution rate is high.

The thermoplastic polyurethane resin used in Kibudemei may be any thermoplastic polyurethane resin that dissolves in acetone, methyl ethyl ketone, dimethyl formamide, or is dispersed in water, such as Crysphon (trade name: manufactured by Dainippon Ink Chemical Co., Ltd.). ), Adekahon Titer (trade name: manufactured by Jimika Kogyo Co., Ltd.) is suitable.

In the present invention, the cord may be a single carbon fiber bundle, but
More preferably, the number of non-combustibles is 30 to 150/kou uA
This is a cord made by doubling together two or more loose bundles to give a number of twists of 30 to 750 twists/m. When the number of non-combustibles is 30/l without swirling,
The code will not be circular and will be poorly organized. 1
When the number exceeds 50 pieces/m, the strength of the fiber bundle decreases. In addition, if the number of ply twists is less than 30/Im, the shape is still
It's not good in terms of cohesion, and if it's over 150GI/i,
The code becomes less powerful.

An example of the method for producing the cord of the present invention is shown below. carbon content of 93% by weight or more, nitrogen content of 1 to 7% by weight, tensile modulus of elasticity of 20x10'kuf/mm' or more, tensile strength of 300 to 9f/am2 or more, preferably tensile strength of 5
Number of single fibers of 00kof/mln' or more 1000 to 1
Use 5,000 acrylic carbon fiber bundles of 50 to 800 tex as an electrolyte! i1'1 Aqueous solutions with acids or nitrates (sodium, potassium, ammonium, etc.)0
．． 01 to 10% by weight, using the carbon fiber as an anode and the solution as a cathode, 20 to 3
The surface of the uA fiber is oxidized by applying electricity of 0.00 coulomb, and then dried. If necessary, after twisting the twisted carbon fibers, two or more carbon fibers are tied together, and then
Further twisting is applied in the opposite direction, and a thermoplastic polyurethane resin is applied to obtain a cord. The adhesion of the thermoplastic polyurethane resin is performed by adding the thermoplastic polyurethane resin to an Iff solvent for 10~
Carbon fibers are dissolved or dispersed in a bath having a concentration of 300 μm/Q, and then dried at a temperature above the boiling point of a solvent or water, or by a conventionally known spray method. The adhesion amount is 3 to 20% by weight, and 3% by weight.
If it is less than 20%, the tensile strength of the cord will be low, and if it exceeds 20%, the strength as a belt will be low and the cord diameter will become thick, which is not preferable. In the thus obtained cord of the present invention, it is preferable that the cord diameter is 1.35 am or less and the cord strength is 9 in 200 or more because it is particularly useful for belts. Diameter is 1.35
If it exceeds +u, the same width as the rotating chain (10mm)
Therefore, it becomes difficult to make a belt with the same level of strength.

〔Effect of the invention〕

By coating charcoal fibers with thermoplastic polyurethane resin, a cord with a high strength contribution ratio can be produced.

When the carbon uA miscellaneous cord of the present invention is used in a belt in combination with thermoplastic polyurethane resin, high strength can be achieved by 1.
Therefore, it is possible to make the belt narrow and thin, and it is possible to reduce the size and weight of the belt including drive parts such as pulleys, which are the rotating parts of the belt. It also has advantages in terms of transportation, such as being able to transport highly loaded materials.

[Actual Examples and Comparative Examples] The present invention will be further explained below with reference to Examples and Comparative Examples. Unless otherwise specified, "parts" and "1%" are by weight.

Examples 1 to 3 and Comparative Example 1 Carbon content 96%, nitrogen content 3.8%, tensile modulus 24x TO' kgr, /u+', tensile strength 53 parts kgr/mm', number of single fibers 12000
．． Fiber bundle f! FFI 330 tex acrylic carbon fiber bundles were immersed in an aqueous solution of 6% nitric acid, the carbon fiber bundle was used as an anode, and the aqueous solution was used as a cathode.The soaked carbon fibers were energized and not energized as shown in Table 1. (Ritanora, thermoplastic polyurethane resin Crisbon Al-1500
(Non-volatile content: 57%, manufactured by Dainippon Ink Chemical Co., Ltd., trade name) A cord having a coating weight of 5% was prepared by immersing it in a bath consisting of 10 parts of methyl ethyl ketone (MEK) and 47 parts of methyl ethyl ketone (MEK), and drying it.

This cord was twisted in the S direction at 100 pieces/ll, and these 1000 pieces were twisted, and twisted in the Z direction at 100 pieces/m to obtain a belt cord.

EK according to Jfs-11017 for the obtained code
After removing the resin and reducing the residual resin to 1% or less, J
[Table 1 also shows the results of measuring strength by a resin impregnation method using an epoxy resin in accordance with 5-R7601. The strong contribution rate was calculated from these values. As shown in Table 1, the code of the present invention showed a high strong contribution rate.

Also, when I measured the diameter of this cord, it was 1,
33mm, but the cord in the scope of the present invention is 200k
gf/ll1m2 or higher.

On the other hand, when the electrical resistance value of the cord was measured, as shown in Table 1, it was found that the electrical resistance change rate was correlated with the cord strength contribution rate.

In accordance with the first indication, it was observed that when combined with a thermoplastic polyurethane resin matrix, it maintained a circular or nearly circular shape, and the cords were evenly distributed within the matrix resin.

Examples 4 to 7 and Comparative Examples 2 to 3 Carbon fiber cords were produced in the same manner as in Example 1, except that the number of twists was changed as shown in Table 2. When the strength contribution ratio was measured, it was found that the cord in the scope of the present invention had a stable strength contribution ratio because it was kept in a circular or nearly circular shape. A carbon fiber cord was produced in the same manner as in Example 1. When we measured its strong contribution rate, we found that the code was 23 strong.
0kQf, strong contribution rate 48%, cord diameter 1.30mm
, and the percentage of strong supporters was low.

Comparative Example 5 In Example 1, a resin system consisting of 93 parts of Epicoat 828 (manufactured by Yuka Shell Epoxy Co., Ltd.) and 3 parts of dicyandiamide as a hardening agent was used instead of the thermoplastic polyurethane resin (case A); Resorcinol formalin latex composition water with the following formulation
47 parts Sodium hydroxide (10% aqueous solution) 1.1 parts Ammonia water (28%) 3.1 parts Resorcinol-pomarine initial condensate 6.2 parts (manufactured by Hodogaya Chemical Co., Ltd.) Vinyl pyridine latex 22.0 parts (Japan) Carbon fibers were prepared in the same manner as in the case (Case B) using 17.5 parts of styrene-butadiene copolymer rubber latex (manufactured by Zeon) and 2.9 parts of formalin (37%) and water instead of the solvent MEK. I created the code. When the chord strength and the strength contribution rate were measured, in the case of A, the chord strength was 265 kOf and the chord contribution rate was 53%. In the case of B, the cord strength was 255 kgf and the cord contribution rate was 50.6%, and the cord strength contribution rate was low in all 8B cases.

Indication of the case Patent Application No. 328493 No. 2 of 1988, Name of the invention Person making the carbon fiber code amendment Address: 103 Relationship to the case Patent applicant Residence 3-3-9 Nihonbashi, Chuo-ku, Tokyo Name (309) Toho Rayon Shinroku Company Representative Keizo Kanee Patent Applicant Tobu Rayon Jinroku Company Patent Attorney Doi 3 Date of order for amendment (voluntary amendment) Column 7 for detailed explanation of the invention in the specification to be amended; Contents of the amendment (1) Changed “Cryshon” from the bottom three lines to the bottom two lines of No. 6 of the specification to “
"Chris Bon," he corrected.

(2) Correct ``Adekahon'' from the bottom two lines to the bottom 1st line of the same 6th line to ``Adekabon''.

(3) On page 10, line 12, "1000 books" is corrected to "4 books."

that's all

Claims (4)

[Claims] (1) A carbon fiber cord having a strength contribution rate (T) of 55% or more for the cord represented by the following formula (1) and coated with a thermoplastic polyurethane resin. T (%) = b / a × 100 (1) T: Strength contribution rate a: Strength (kg) measured according to JIS-R7601 after removing resin from carbon fiber cord b: Carbon fiber Cord strength (kg) (2) The carbon fiber cord according to claim (1), wherein the carbon fiber cord has a number of ply twists of 30 to 150 pieces/m, which is obtained by splicing two or more carbon fiber bundles with a nonflammable number of 30 to 150 pieces/m. (3) The carbon fiber cord according to claim (1), which has a diameter of 1.35 mm or less and a strength of 200 kg or more. (4) The carbon fiber cord according to claim (1), wherein the thermoplastic polyurethane resin is contained in an amount of 3 to 20% by weight based on the carbon fiber cord.