JPH1112929A - Method for adhesive treatment of aramid fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for adhesive treatment of aramid fiber cords excellent in adhesive properties with hydrogenated acrylonitrile-butadiene rubber having little polarity. SOLUTION: This method for adhesive treatment of aramid fibers is to apply a first treating solution comprising a polyisocyanate compound containing >=2 isocyanate groups or its terminal-blocked compound as a main component, heat treat at a temp. of 80-130 deg.C for 60-80 seconds, then, in a twisted state, apply a second treating agent containing (a) resorcin formalin, (b) 4-6 pts. solid wt. of a hydrogenated acrylonitrile-butadiene rubber latex based on 1 pt.wt. of resorcin formalin and (c) resorcin formalin containing 3-5 pts. solid wt. of chlorophenol based on 1 pt.wt. of resorcin formalin and heat treat at a temp. of 180-240 deg.C for 60-180 seconds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aramid fiber bonding method which can be suitably used as a power transmission belt reinforcing cord. In particular, the present invention relates to a method for bonding aramid fiber, which is suitable as a core wire cord of a belt and has particularly good adhesion to a heat-resistant matrix rubber and excellent durability.

[0002]

2. Description of the Related Art Aramid fiber cords generally have excellent properties such as strength, elastic modulus, dimensional stability, and heat resistance, so that rubber composites such as belts used under high load and severe conditions are used. It is useful as an excellent reinforcing fiber, and is expected to expand its use.

[0003] In general, reinforcing fibers for composites such as belts are used in the form of twisted cords. Important properties for this cord include adhesion to matrix rubber, cord strength, balance between load elongation and dry heat shrinkage, heat shrinkage stress, and the like. Among these properties, the adhesive performance and the cord strength greatly affect the load resistance and durability of the completed belt.

[0004] Regarding the adhesion between the aramid fiber cord and the rubber matrix, various kinds of RFL adhesives have been proposed. In particular, regarding the adhesion to hydrogenated acrylonitrile-butadiene rubber, which is a high heat-resistant rubber matrix, it is known to use a two-stage treatment of an epoxy compound and resorcinol-formalin rubber latex (for example, see JP-A-6-25977). No., JP-A-6-2597
No. 8).

[0005] However, the above adhesive treatment alone does not exhibit sufficient adhesiveness, and in actuality, when molding into a belt or the like, the rubber to be adhered is dissolved in a polar solvent. The fact is that we are processing.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for bonding an aramid fiber cord having improved adhesiveness. It is an object of the present invention to provide a method for bonding an aramid fiber cord which is particularly suitable for obtaining a belt or the like having excellent adhesion to a matrix rubber and excellent durability.

[0007]

Means for Solving the Problems The object of the present invention is to provide:
(1) Aramid fiber is provided with a first treatment liquid mainly containing a polyisocyanate compound containing two or more isocyanate groups or a compound having a terminal blocked,
After a heat treatment at a temperature of 80 to 130 ° C. for 60 to 180 seconds,
In the twisted state, (a) resorcinol / formalin, and (b) the solid content weight ratio with the resorcinol / formalin is 1: 4 to
A second processing solution containing 1: 6 hydrogenated acrylonitrile-butadiene rubber latex and (c) a chlorophenol-containing resorcinol / formalin having a solids weight ratio with the resorcinol / formalin of 1: 3 to 1: 5 is applied. Aramid fiber bonding treatment method, wherein heat treatment is performed at a temperature of 180 to 240 ° C. for 60 to 180 seconds, (2) the first treatment liquid is prepared by adding diphenylmethane-4,4′-diisocyanate to toluene in an amount of 5 to 10 wt. (1) The method for bonding an aramid fiber according to (1), which is a treatment solution in which the solution is dissolved in dimethylform, wherein (3) the first treatment solution is a compound in which both terminals of diphenylmethane-4,4′-diisocyanate are blocked with an oxime compound. This is achieved by the method for bonding aramid fibers described in (1), which is a processing solution in which 5 to 10% by weight is dissolved in amide.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The aramid fiber used in the present invention is a fiber comprising a polymer in which a repeating unit in which an aromatic ring is bonded by an amide bond accounts for at least 80% or more of the whole.

Typical examples of fibers comprising these polymers or copolymers include conventionally known fibers comprising aramid such as polyparaphenylene terephthalamide and polyparaphenylene / 3,4'diphenylether terephthalamide. be able to.

The polyisocyanate compound for treating aramid fibers is based on diphenylmethane-4,4'-diisocyanate having two isocyanate groups in one molecule, which is directly dissolved in a toluene solution, or a mixture of both isocyanates. It is preferable to dissolve a compound whose terminal is blocked with an oxime compound in dimethylformamide.

The concentration of isocyanate in the solution is
5 to 10% by weight. If the concentration is less than 5% by weight,
If the adhesion to the aramid fiber is not sufficient during the immersion treatment, on the other hand, if the concentration exceeds 10% by weight, the reaction of the isocyanate is accelerated when applied to the aramid fiber, so that the viscosity changes and the amount of the adhesion to the fiber is reduced. Fluctuation is likely to occur, and the adhesion performance to the matrix may be uneven.

The above-mentioned treating solution containing a polyisocyanate compound is usually applied as a fiber surface treating agent during the production of aramid fibers or after the production of aramid fibers. 0.1 to 5.0% by weight of solid content adhered to aramid fiber
At 80-130 ° C for 60-
Dry for 180 seconds.

The aramid fiber treated with the treating agent containing the polyisocyanate compound in the case of a non-twisted yarn,
Subsequently, a plurality of wires are twisted with a predetermined twist number and configuration to obtain an aramid fiber cord.

The aramid fiber cord treated with the polyisocyanate compound is continuously treated with RF as the second treating agent.
L (resorcin / formalin / hydrogenated acrylonitrile-butadiene rubber latex) and chlorophenol-containing resorcin / formalin are immersed in a treatment liquid.

The atmosphere at this time may be under normal pressure, reduced pressure, or pressurized condition. Since there is a difference in the state of impregnation of the treatment agent into the aramid fiber cord depending on the pressure condition, it may be appropriately selected according to the application.

The RFL used here is used at a molar ratio of resorcinol to formalin of 1: 0.1 to 1: 8, preferably 1: 1 to 1: 4. The mixing ratio of resorcinol / formalin and hydrogenated acrylonitrile-butadiene rubber latex is 1: 4 to 1: in terms of solid content weight ratio.
6 is required.

If the compounding ratio of the rubber latex is more than the above range, the viscosity of the treating agent becomes high, and gelling rarely occurs, so that uniform adhesion cannot be achieved, leading to instability of the adhesive performance. On the other hand, if the compounding ratio of the rubber latex is less than the above range, sufficient adhesive performance will not be exhibited.

Further, in the present invention, it is essential to incorporate a chlorophenol-based RF having an affinity for the polar rubber matrix. The above RF and this chlorophenol R
The compounding ratio of F needs to be 1: 3 to 1: 5 in solid content ratio. If the blending ratio of the chlorophenol-based RF is less than the above range, sufficient adhesive performance will not be exhibited. On the other hand, if the blending ratio of the chlorophenol-based RF is greater than the above range, the cohesive force of the adhesive layer will be low, so that the adhesive layer The adhesive itself becomes brittle, which causes a problem in durability of adhesiveness.

When the aramid fiber cord is immersed in the second treating agent containing RFL, the solid content of the treating agent on the aramid fiber cord is preferably 4 to 8% by weight based on the weight of the cord. When the amount of adhesion is less than 4% by weight, no adhesive performance is exhibited, while when it exceeds 8% by weight,
Poor handling of the code may cause troubles such as scum during the process.

After the application of the second treating agent, the temperature of the
Drying is performed at 180 ° C. for 60 to 180 seconds, and subsequently, heat treatment is performed at a temperature of 180 to 240 ° C. for 60 to 180 seconds.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to practical examples. The cord strength, cord peeling adhesive strength, and pull-out adhesive strength in Examples were measured by the following methods.

<Cord Strength> Using an Instron 5565 type tensile tester (manufactured by Instron), a test length (cord length) of 250 mm was taken using a 4D air chuck, and the breaking strength was measured at a pulling speed of 100 mm / min. I asked.
The measurement was performed 10 times, and the average value was defined as the cord strength.

<Cord Peeling Adhesive Strength> This shows the peeling adhesive strength between the treated cord and the rubber. 25 cords are buried near the surface of the rubber sheet and vulcanized at a temperature of 150 ° C. for 20 minutes under a pressing pressure of 50 kg / cm ² , and then 25 cords are simultaneously peeled from the rubber sheet at a rate of 200 mm / min. The required force was measured and indicated as N / 25.

<Pull-out adhesive force> This shows the shear adhesive force between the treated cord and rubber. The cord is embedded in a rubber block, vulcanized at a temperature of 150 ° C. for 20 minutes under a pressing pressure of 50 kg / cm ² , and then the cord is pulled out of the rubber block at a speed of 200 mm / min, and the force required for pulling is measured. , N / cm.

[Examples 1 and 2] First, the first treating agent was prepared as follows. That is, diphenylmethane-4,4
To 10 g of '-diisocyanate (reagent first grade; manufactured by Tokyo Chemical Industry Co., Ltd., concentration: 99.9%), 90 g of toluene (reagent first grade; manufactured by Nacalai Tesque, Inc.) as a solvent is added, and the mixture is stirred well. This is designated as solution A. On the other hand, Elastron BN
10 g of the original 69 (oxime block of diphenylmethane-4,4-'diisocyanate; manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd .; concentration: 99%) was added to 90 g of dimethylformamide (first-class reagent; manufactured by Nacalai Tesque, Inc.). Then, stir well to dissolve, and use this solution B.

Next, the second treating agent was adjusted as follows. 223.5 g of water in 10% aqueous solution of sodium hydroxide,
13.3 g is added thereto, and 17.0 g of resorcinol (reagent 1st grade; manufactured by Nacalai Tesque, Inc .; concentration: 100%) is added thereto and stirred. Then formalin (reagent 1)
Grade; manufactured by Nacalai Tesque KK; concentration 37%) 14.9
Add g and stir. When the whole is dissolved, it is left still in an atmosphere of 20 ° C. for 4 hours to be pre-ripened. After a predetermined time, hydrogenated acrylonitrile-butadiene rubber latex (prototype manufactured by Sumitomo Seika Co., Ltd .;
%) 281.3 g was added with gentle stirring, and the mixture was allowed to stand for another 24 hours to be pre-ripened. Then, Denabond E (Chlorophenol-based R manufactured by Nagase Kasei Kogyo Co., Ltd.)
F; concentration 20%) and add 450.0 g with stirring,
Let stand for 2 hours.

Aramid fiber of 1500 denier / 1000 filament (manufactured by Teijin Limited; trade name: Technora)
Is twisted in the Z direction at 38 T / 10 cm. Next, two of the lower twisted yarns are aligned and 28T / 10c in the S direction.
m was twisted to obtain a raw cord having a 1500/2 configuration.

The obtained raw cord was immersed in liquid A (Example 1) or liquid B (Example 2) of the first treatment liquid, using a computer treater (tire code processing machine manufactured by CA Ritzler Co., Ltd.). Thereafter, heat treatment was performed at 90 ° C. for 120 seconds.

Next, after immersion in the second treatment liquid,
Dry at 60 ° C. for 120 seconds followed by 1 hour at 240 ° C.
Heat treatment was performed for 20 seconds to obtain an adhesive-treated aramid fiber cord. The adhesion amount of each processing solution was adjusted so as to be 1 to 3% by weight of the first processing agent and 4 to 6% by weight of the second processing agent.

[0030] The obtained aramid fiber treated cord was
NBR (hydrogenated acrylonitrile butadiene rubber)
Was press-vulcanized at 150 ° C. for 20 minutes at a pressure of 50 kg / cm ² to obtain a rubber composite.

Examples 3 to 6 and Comparative Examples 1 to 8 In Examples 1 and 2, the polyisocyanate compound of the first treating agent was used as it was, and the RF / L and RF / chlorophenol RF of the second treating agent were used. Was changed in the same manner as in Examples 1 and 2, except that the ratio of was changed as shown in Table 1, to obtain a rubber composite. Table 1 shows the results of measuring the cord strength, the peel adhesive strength, and the pull-out adhesive strength of these, together with Examples 1 and 2.

[0032]

[Table 1]

[0033]

The aramid fiber cord obtained by the method of the present invention maintains the excellent mechanical properties of aramid fiber in terms of strength, and has a composite containing hydrogenated acrylonitrile butadiene rubber as a main component having poor polarity. It shows excellent adhesion to the matrix rubber when reinforcing the body.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI D06M 15/693 D06M 15/693

Claims (3)

[Claims] 1. An aramid fiber having two isocyanate groups.
After applying a first treatment liquid containing a polyisocyanate compound containing at least one polyisocyanate compound or a compound having its terminal blocked as a main component and performing a heat treatment at a temperature of 80 to 130 ° C. for 60 to 180 seconds, (a) resorcinol in a twisted state; ·formalin,
(B) a hydrogenated acrylonitrile-butadiene rubber latex having a solid content ratio with the resorcinol-formalin of 1: 4 to 1: 6, and (c) a solid content weight ratio with the resorcinol-formalin of 1: 3 to 1 A method for bonding aramid fibers, comprising: applying a second treatment liquid containing chlorophenol-containing resorcinol-formalin of No. 5 and performing a heat treatment at a temperature of 180 to 240 ° C. for 60 to 180 seconds. 2. The method according to claim 1, wherein the first processing liquid is diphenylmethane-4,
The method for bonding aramid fibers according to claim 1, wherein the processing liquid is 4 to 10% by weight of 4'-diisocyanate dissolved in toluene. 3. The method according to claim 1, wherein the first processing liquid is diphenylmethane-4,
A compound in which both terminals of 4'-diisocyanate are blocked with an oxime compound is added to dimethylformamide in an amount of 5 to 10%.
The method for bonding aramid fibers according to claim 1, which is a treatment solution in which the solution is dissolved by weight.