Coating processes – Coating remains adhesive or is intended to be made adhesive
Reexamination Certificate
2001-03-27
2003-03-04
Barr, Michael (Department: 1762)
Coating processes
Coating remains adhesive or is intended to be made adhesive
C427S175000, C427S386000, C427S407100, C427S413000, C156S175000
Reexamination Certificate
active
06528113
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for producing an adhesive-treated polyester fiber cord useful as a reinforcing cord for a power-transmission belt. More particularly, the present invention relates to a process for producing an adhesive-treated polyester fiber cord which is suitable as a core cord of a lapped V belt and has an excellent handling property in a belt-forming procedure, an excellent adhesion to non-vulcanized rubber used in a belt-forming procedure, and a superior bonding property to a matrix rubber after vulcanization of the rubber, and exhibits an excellent adhesive durability to such an extent that even when the cord is brought into contact with water vapor during the vulcanizing procedure, the adhesive property of the cord is not degrated, and a superior belt-forming property.
BACKGROUND ART
A polyester fiber cord generally has excellent mechanical strength, modulus of elasticity, dimensional stability and heat resistance, and thus is useful as an excellent reinforcing cord for rubber-composite materials, for example, tires, belts and hoses which are employed under severe conditions, and thus the use of the polyester fiber cord is expected to increase.
Generally, the reinforcing fibers for rubber-composite materials, for example, belts, are employed in the form of a twisted yarn cord. The important properties for the cord are a high adhesive property of the cord to matrix rubber, a high mechanical strength of cord, a good balance between elongation under load and dry heat shrinkage of the cord, an appropriate heat shrinkage stress, and a superior adhesion of the cord to the non-vulcanized rubber in a forming procedure. For example, in the case of a belt, among the above-mentioned properties, the adhesive property and the mechanical strength of the cord significantly contribute to enhancing the load resistance and durability of the resultant belt, and the balance between the elongation under load and the dry heat shrinkage influences the dimensional change, (for example, the length) of the belt during movement of the belt, and closely relates to a power transmission efficiency of the belt. Further, the adhesion of the belt to the non-vulcanized rubber in a belt-forming procedure is a property special to the belt-forming procedure and closely relates to peeling or separation of the cord from the non-vulcanized rubber subjected to the belt-forming procedure and directly influences the yield of the product. Therefore, an adhesion process technology which enables the resultant product to exhibit well balanced properties, as mentioned above, is desired.
With respect to an adhesion of a polyester fiber cord with a rubber matrix, various types of resorcinol-formaldehyde latex adhesives (RF
r
adhesives) are provided by, for example, Japanese Unexamined Patent Publications No. 57-187,238 and No. 60-110,980 and Japanese Examined Patent Publication No. 8-2,971. When these adhesives are employed, the adhesion performance of the polyester fiber cord as a reinforcing fiber cord for power transmission belt is certainly sufficient, but the adhesives are disadvantageous in that the adhesion of the cord with the non-vulcanized rubber in the belt-forming procedure is insufficient and peeling or separation of the cord from the rubber matrix frequently occurs. Therefore, in the present stage, the close adhesion of the cord with the non-vulcanized rubber in the belt-forming procedure is ensured by coating a rubber adhesive prepared by dissolving an adhesive rubber in a solvent and in a small amount, on a periphery of a cord coated with an RF
r
adhesive.
However, the above-mentioned rubber adhesive causes the working environment for the belt-forming procedure to be bad and sticking of the non-dried rubber adhesive to a worker's body is unhealthy. Also, the treatment with the solvent-containing rubber adhesive is disadvantageous in that the waste liquid-treatment cost is high and the working environment is bad, in comparison with the aqueous treatment.
DISCLOSURE OF THE INVENTION
The present invention was made, against the above-mentioned background, to provide a process for producing an adhesive-treated polyester fiber cord having excellent handling property and adhesion of the cord to non-vulcanized vulcanized rubber in a forming procedure, and a superior bonding property of the cord with a matrix rubber, and useful for rubber composite materials, particularly a power-transmission belt, having a high durability.
The process for producing an adhesive-treated polyester fiber cord of the present invention comprises:
subjecting a non-twisted or twisted polyester fiber cord to a first adhesive-treating procedure in which a first adhesive liquid comprising a polyepoxide compound and a blocked polyisocyanate compound in a solid weight ratio of 1/3 to 1/5 is applied to the polyester fiber cord and the first adhesive liquid-applied polyester fiber cord is heat treated at a temperature of 160 to 240° C.;
twisting, where the polyester fiber cord has no twist, the non-twisted polyester fiber cord;
subjecting the first adhesive-treated polyester fiber cord to a second adhesive-treating procedure in which a second adhesive liquid comprising a resorcinol-formaldehyde condensation product resin and a rubber latex in an effective component weight ratio of 1/3 to 1/15, is applied to the first adhesive-treated polyester fiber cord, and the second adhesive liquid-applied polyester fiber cord is heat-treated at a temperature of 180 to 240°C.; and
subjecting the second adhesive-treated polyester fiber cord to a third adhesive-treating procedure in which a third adhesive liquid comprising an aqueous dispersion of a resorcinol-formaldehyde condensation product component (RF) in a molar ratio (R/F) of resorcinol (R) to formaldehyde (F) of 1/0.6 to 1/1.0 and a rubber component (G) containing natural rubber (NR) in a content of at least 15% by weight based on the total weight of the rubber component (G), in a solid weight ratio (RF/G) of the resorcinol-formaldehyde condensation product component (RF) to the rubber component (G) of 1/10 to 1/20 is applied to the second adhesive-treated polyester fiber cord, and the third adhesive liquid-applied polyester fiber cord is heat-treated at a temperature of 140 to 170° C.
In the process for producing an adhesive-treated polyester fiber cord of the present invention, preferably, the polyester fibers in the polyester fiber cord are fibers treated with an epoxy compound during a fiber-forming procedure.
In the process for producing an adhesive-treated polyester fiber cord of the present invention, the polyepoxide compound contained in the first adhesive liquid is preferably selected from glycidyl ether compounds of polyhydric alcohol compounds.
In the process for producing an adhesive-treated polyester fiber cord of the present invention, the polyepoxide compound in the first adhesive liquid preferably has an epoxy group content of 0.2 equivalent or more per 100 g of the polyepoxide compound.
In the process for producing an adhesive-treated polyester fiber cord of the present invention, the blocked polyisocyanate compound is preferably selected from addition reaction products of a polyisocyanate compound with a blocking agent comprising at least one member selected from oxime compounds, phenol compounds and caprolactam.
In the process for producing an adhesive-treated polyester fiber cord of the present invention, the first adhesive-treated polyester fiber cord preferably has the first adhesive in a total solid weight of 0.5 to 1.5% by weight based on the polyester fiber cord.
In the process for producing an adhesive-treated polyester fiber cord of the present invention, the heat treatment for the first adhesive liquid-applied polyester fiber cord is preferably carried out under a stretched condition under which the first adhesive liquid-applied polyester fiber cord is elongated at an elongation of 2.0 to 4.5%.
In the process for producing an adhesive-treated polyester fiber cord of the present invention, the rubber latex contained in th
Kuroda Toshimasa
Makino Shoji
Watanabe Hirosuke
Barr Michael
Blanton Rebecca A.
Sughrue & Mion, PLLC
Teijin Limited
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