REINFORCING FIBER, METHOD FOR MANUFACTURING SAME, AND MOLDED BODY USING SAME

Abstract

Provided are reinforcing fibers using an adhesive component not containing resorcinol and formaldehyde, which are excellent in adhesiveness to rubber and which can be efficiently produced while preventing contamination of production facilities, and a method for producing them, as well as a molded article using them. The reinforcing fibers have an adhesive component that contains a conjugated diene rubber and an oil, in at least a part of the surfaces thereof, wherein the vapor pressure at 20° C. of the oil is 10 Pa or less.

Claims

1. Reinforcing fibers, comprising: fibers; and an adhesive component; wherein: the adhesive component comprises a conjugated diene rubber and an oil; the adhesive component is present in at least a part of surfaces of the fibers; and a vapor pressure of the oil at 20° C. is 10 Pa or less.

2. The reinforcing fibers according to claim 1, wherein: the fibers comprise hydrophilic fibers; and the hydrophilic fibers comprise at least one selected from group consisting of polyvinyl alcohol fibers, regenerated cellulose fibers, and fibers prepared by hydrophilizing surfaces of hydrophobic fibers.

3. The reinforcing fibers according to claim 2, wherein: the hydrophilic fibers comprise and fibers prepared by hydrophilizing surfaces of hydrophobic fibers; and the hydrophobic fibers comprise polyester fibers.

4. The reinforcing fibers according to claim 1, wherein the conjugated diene rubber is liquid.

5. The reinforcing fibers according to claim 1, wherein the conjugated diene rubber comprises monomer units derived from at least one selected from the group consisting of butadiene, isoprene, and farnesene.

6. The reinforcing fibers according to claim 1, wherein a melt viscosity of the conjugated diene rubber at 38° C. is 4,000 Pa.Math.s or less.

7. The reinforcing fibers according to claim 1, wherein a number-average molecular weight (Mn) of the conjugated diene rubber is 2,000 to 120,000.

8. The reinforcing fibers according to claim 1, wherein the conjugated diene rubber is a modified conjugated diene rubber comprising a hydrogen-bonding functional group.

9. The reinforcing fibers according to claim 8, wherein the hydrogen-bonding functional group is at least one selected from the group consisting of a hydroxy group, an aldehyde group, an acetalized form of an aldehyde group, a carboxy group, a salt of a carboxy group, an ester form of a carboxy group, an acid anhydride of a carboxy group, a silanol group, an ester form of a silanol group, an amino group, an imidazole group, and a mercapto group.

10. The reinforcing fibers according to claim 1, wherein the adhesive component is present in the reinforcing fibers in an amount of 0.01 to 10 parts by mass relative to 100 parts by mass of the fibers.

11. The reinforcing fibers according to claim 1, wherein the adhesive component comprises the conjugated diene rubber if in an amount of 1% to 80% by mass.

12. The reinforcing fibers according to claim 1, wherein the of adhesive component comprises the oil in an amount of 20% to 90% by mass.

13. The reinforcing fibers according to claim 1, wherein a flash point of the oil is 70° C. or higher.

14. A method for producing the reinforcing fibers of claim 1, comprising adhering a mixture of the conjugated diene rubber and the oil to the fibers.

15. A fabric comprising the reinforcing fibers of claim 1, wherein the fabric is a woven fabric or a knitted fabric.

16. A molded article obtained by molding a composition comprising the reinforcing fibers of claim 1.

17. The molded article according to claim 16, wherein the composition further comprises a rubber component.

18. The molded article according to claim 16, wherein the molded article is in the form of a tire, a belt, or a hose.

Description

EXAMPLES

[0185] Hereinunder the present invention is described further specifically with reference to Examples, but the present invention is not whatsoever restricted by these Examples.

[0186] Production of modified conjugated diene rubber having monomer unit represented by the following formula (1a):

##STR00001##

Production Example 1: Production of Modified Conjugated Diene Rubber (A-1)

[0187] A fully-dried 5-L autoclave was purged with nitrogen, then 1200 g of hexane and 26.2 g of n-butyl lithium (17 mass % hexane solution) were put thereinto, heated up to 50° C., and then with stirring and controlling the polymerization temperature so as to he at 50° C., 1200 g of isoprene was sequentially added and polymerized for 1 hour. Subsequently, methanol was added to stop the polymerization reaction to give a polymer solution. Water was added to the resultant polymer solution and stirred, and the polymer solution was thus washed with water. Stirring was stopped, and after separation of the polymer solution phase from the water phase was confirmed, water was removed. The polymer solution after washing was dried in vacuum at 70° C. for 24 hours to give an unmodified liquid polyisoprene (A′-1).

[0188] Subsequently, in a 1-L autoclave purged with nitrogen, 500 g of the resultant unmodified liquid polyisoprene (A′-1) was put, and 25 g of maleic anhydride and 0.5 g of butylated hydroxytoluene (BHT) were added, and reacted at 170° C. for 15 hours to give a maleic anhydride-modified liquid polyisoprene (A-1).

Production Example 2: Production of Modified Conjugated Dime Rubber (A-2)

[0189] A fully-dried 5-L autoclave was purged with nitrogen, then 600 g of cyclohexane and 212 g of sec-butyl lithium (10.5 mass % cyclohexane solution) were put thereinto, heated up to 70° C., and then with stirring and controlling the polymerization temperature so as to be 70° C., 2050 g of isoprene was sequentially added and polymerized for 1 hour. Subsequently, methanol was added to stop the polymerization reaction to give a polymer solution. Water was added to the resultant polymer solution and stirred, and the polymer solution was thus washed with water. Stirring was stopped, and after separation of the polymer solution phase from the water phase was confirmed, water was removed. The polymer solution after washing was dried at 70° C. for 24 hours to give an unmodified liquid polyisoprene (A′-2).

[0190] Subsequently, in a 1-L autoclave purged with nitrogen, 500 g of the unmodified liquid polyisoprene (A′-2) produced according to the same process as in Production Example 1 was put, and 50 g of maleic anhydride and 0.5 g of butylated hydroxytoluene (BHT) were added, and reacted at 170° C. for 15 hours to give a maleic anhydride-modified liquid polyisoprene (A-2),

Production of Modified Conjugated Diene Rubber Having Monomer Unit Represented by the Following Formula (1b)

[0191] ##STR00002##

Production Example 3: Production of Modified Conjugated Diene Rubber (A-3)

[0192] A fully-dried 5-L autoclave was purged with nitrogen, then 1260 g of hexane and 36.3 g of n-butyl lithium (17 mass % hexane solution) were put thereinto, heated up to 50° C., and then with stirring and controlling the polymerization temperature so as to be at 50° C., 1260 g of butadiene was sequentially added and polymerized for 1 hour. Subsequently, methanol was added to stop the polymerization reaction to give a polymer solution. Water was added to the resultant polymer solution and stirred, and the polymer solution was thus washed with water. Stirring was stopped, and after separation of the polymer solution phase from the water phase was confirmed, water was removed. The polymer solution after washing was dried in vacuum at 70° C. for 24 hours to give an unmodified liquid polybutadiene (A′-3).

[0193] Subsequently, in a 1-L autoclave purged with nitrogen, 500 g of the resultant unmodified liquid polybutadiene (X-3) was put, and 25 g of maleic anhydride and 0.5 g of N-phenyl-N′-(1,3-dimethylbutyl)-p-phenylenediamine (trade name “Nocrac. GC”, by Ouchi Shinko Chemical Industrial Co., Ltd.) were added, and reacted at 170° C. for 24 hours to give a maleic anhydride-modified liquid polybutadiene (A-3).

Production Example 4: Production of Modified Conjugated Diene Rubber (A-4)

[0194] A fully-dried 5-L autoclave was purged with nitrogen, then 1140 g of hexane and 20.9 g of n-butyl lithium (17 mass % hexane solution) were put thereinto, heated up to 50° C., and then with stirring and controlling the polymerization temperature so as to be at 50° C., 1390 g of butadiene was sequentially added and polymerized for 1 hour. Subsequently, methanol was added to stop the polymerization reaction to give a polymer solution. Water was added to the resultant polymer solution and stirred, and the polymer solution was thus washed with water. Stirring was stopped, and after separation of the polymer solution phase from the water phase was confirmed, water was removed. The polymer solution after washing was dried in vacuum at 70° C. for 24 hours to give an unmodified liquid polybutadiene (A′-4).

[0195] Subsequently, in a 1-L autoclave purged with nitrogen, 500 g of the resultant unmodified liquid polybutadiene (A′-4) was put, and 15 g of maleic anhydride and 0.5 g of N-phenyl-N′-(1,3-dimethylbutyl)-p-phenylenediamine (trade name “Nocrac GC”, by Ouchi. Shinko Chemical Industrial Co., Ltd.) were added, and reacted at 170° C. for 24 hours to give a maleic anhydride-modified liquid polybutadiene (A-4).

Production of Modified Conjugated Diene Rubber Having Monomer Unit Represented by the Following Formula (1C0:

[0196] ##STR00003##

Production Example 5: Production of Modified Conjugated Diene Rubber (A-5)

[0197] 5.4 g of methanol was added to 315 g of maleic anhydride-modified liquid polybutadiene (A-3) obtained according to the same process as in Production Example 3, and reacted at 80° C. for 6 hours to give a monomethyl maleate-modified liquid polyhutadiene (A-5).

Production of Modified Conjugated Diene Rubber Having Monomer Unit Represented by the Following Formula (A-5)

[0198] ##STR00004##

Production Example 6: Production of Modified Conjugated Diene Rubber (A-6)

[0199] A fully-dried autoclave was purged with nitrogen, then 1500 g of cyclohexane and 18.2 g of sec-but.sub.3;l lithium (10.5 mass % cyclohexane solution) were put thereinto, heated up to 50° C., and then 1500 g of a previously-prepared. mixture of 900 g of butadiene (a) and 600 g of farnesene (b) (butadiene (a) and farnesene (b) were mixed in a tank) was added at a rate of 10 ml/min, and polymerized for 1 hour. Subsequently, methanol was added to stop the polymerization reaction to give a polymer solution. Water was added to the resultant polymer solution and stirred so as to wash the polymer solution with water. Stirring was stopped, and after separation of the polymer solution phase from the water phase was confirmed, water was removed. The polymer solution after washing was dried in vacuum at 70° C. for 12 hours to give an unmodified liquid polyfarnesene-polybutadiene copolymer (A″-6).

[0200] Subsequently, in a 1-L autoclave purged with nitrogen, 500 g of the resultant unmodified liquid polyfarnesene-polybutadiene copolymer (A″-6) was put, and 25 g of maleic anhydride and 0.5 g of N-phenyl-N′-(1,3-dimethylbutyl-p-phenylenediamine (trade name “Nocrac 6C”, by Ouchi Shinko Chemical Industrial Co., Ltd.) were added, and reacted at 170° C. for 24 hours to give a maleic anhydride-modified liquid polyfarnesene-polybutadiene copolymer (A′-6). Further, 5.6 g of methanol was added to 300 g of the resultant maleic anhydride-modified liquid polyfarnesene-polybutadiene copolymer (A′-6), and reacted at 80° C. for 6 hours to give a monomethyl maleate-modified liquid polyfarnesene-polybutadiene copolymer (A-6).

Production of Modified Conjugated Diene Rubber Having Monomer Unit, Represented by the Following Formula (1e):

[0201] ##STR00005##

Production Example 7: Production of Modified Conjugated Diene Rubber (A-7)

[0202] A fully-dried 5-L autoclave was purged with nitrogen, then 1500 g of cyclohexane and 10.5 g of sec-butyl lithium (10.5 mass% cyclohexane solution) were put thereinto, heated up to 50° C., and then 1500 g of a previously-prepared mixture of 600 g of butadiene (a) and 900 g of farnesene (b) (butadiene (a) and farnesene (b) were mixed in a tank) was added at a rate of 10 ml/min, and polymerized for 1. hour. Subsequently, methanol was added to stop the polymerization reaction to give a polymer solution. Water was added to the resultant polymer solution and stirred so as to wash the polymer solution with water. Stirring was stopped, and after separation of the polymer solution phase from the water phase was confirmed, water was removed. The polymer solution after washing was dried in vacuum at 70° C. for 12 hours to give an unmodified liquid polyfarnesene-polybutadiene copolymer (A′-7).

[0203] Subsequently, in a 1-L autoclave purged with nitrogen, 500 g of the resultant unmodified liquid polyfarnesene-polybutadiene copolymer (A′-7) was put, and 25 g of maleic anhydride and 0.5 g of N-phenyl-N′-(1,3-dimethylbutyl)-p-phenylenediamine (trade name “Nocrac 6C”, by Ouchi Shinko Chemical Industrial Co., Ltd.) were added, and reacted at 170° C. for 24 hours to give a maleic anhydride-modified liquid polyfarnesene-polybutadiene copolymer (A-7).

[0204] Measurement methods and calculation methods for the physical properties of modified conjugated diene rubbers are as follows. The results are shown in Table 1.

[0205] Mw, Mn and Mw/Mn of the modified conjugated diene rubber were determined as standard polystyrene-equivalent values through GPC (gel permeation chromatography). The apparatus and the condition for measurement are as follows,

Apparatus: “GPC apparatus GPC8020” from. Tosoh Corporation
Separation column: “TSKgel G40001HXL” from Tosoh Corporation
Detector: “RI-8020” from Tosoh Corporation

Eluent: Tetrahydrofuran

[0206] Eluent flow rate: 1.0 ml/min
Sample concentration: 5 mg/1.0 ml.
Column temperature: 40° C.

[0207] The melt viscosity at 38° C. of the modified conjugated diene rubber was measured using a Brookfield viscometer (from Brookfield Engineering Labs. Inc.).

[0208] 10 mg of the modified conjugated diene rubber was put in an aluminum pan, and the thermogram thereof was measured through differential scanning colorimetry (DSC) under a temperature elevation speed condition of 10° C./min, and the peak top value in DDSC was referred to as a glass transition temperature of the rubber.

[0209] The average number of the hydrogen-bonding functional groups per molecule of the modified conjugated diene rubber was calculated from the equivalent (g/eq) of the hydrogen-bonding functional group of the modified conjugated diene rubber and the styrene-equivalent number-average molecular weight Mn thereof, according to the following expression.

Average number of hydrogen-bonding functional groups per molecule=[(number-average molecular weight (Mn))/(molecular weight of styrene unit)×(average molecular weight of conjugated diene and any other optional monomer unit than conjugated diene)]/(equivalent of hydrogen-bonding functional group)

[0210] The method for calculating the equivalent of the hydrogen-bonding functional group can be appropriately selected depending on the kind of the hydrogen-bonding functional group.

[0211] The average number of the hydrogen-bonding functional groups per molecule of a maleic anhydride-modified conjugated diene rubber and a monomethyl maleate-modified conjugated diene rubber was calculated by determining the acid value of the maleic anhydride-modified conjugated diene rubber and the monomethyl maleate-modified conjugated diene rubber, and calculating the equivalent (g/eq) of the hydrogen-bonding functional group from the acid value.

[0212] A modified sample was washed four times with methanol (5 mL per gram of the sample) to remove impurities such as antioxidant, and then the sample was dried under reduced pressure at 80° C. for 12 hours. 180 mL of toluene and 20 mL of ethanol were added to 3 g of the modified sample to dissolve the sample therein, and then this was subjected to neutralization titration with an ethanol solution of 0.1 N potassium hydroxide to determine the acid value thereof according to the following expression.

[0213] Acid Value (mgKOH/g)=(A.Math.B)×F×5.611/S

[0214] A: Amount (mL) of ethanol solution of 0.1 N potassium hydroxide needed for neutralization.

[0215] B: Amount (mL) of ethanol solution of 0.1 N potassium hydroxide in sample-free blank.

[0216] F: Titer of ethanol solution of 0.1 N potassium hydroxide.

[0217] S: Mass (g) of weighed sample.

[0218] From the acid value, the mass of the hydrogen-bonding functional group contained in 1 g of the maleic anhydride-modified conjugated diene rubber or the inonomethyl maleate-modified conjugated diene rubber was calculated according to the following expression, and further the mass (polymer chain mass) except the functional group contained in 1 g of the maleic anhydride-modified conjugated diene rubber or the inonomethyl maleate-modified conjugated diene rubber was calculated. With that, the equivalent of the hydrogen-bonding functional group (g/eq) was calculated according to the following expression.

[Mass of hydrogen-bonding functional group per gram]=[acid. value]/[56.11]×[molecular weight of hydrogen-bonding functional group]/1000

[Mass of polymer main chain per gram]=1−[mass of hydrogen-bonding functional group per gram]

[Equivalent of hydrogen-bonding functional group]=[mass of polymer main chain per gran]/([mass of hydrogen-bonding functional group per gram]/[molecular weight of hydrogen-bonding functional group])

TABLE-US-00001 TABLE 1 Molecular Melt Glass Average Number of Weight Viscosity Transition Hydrogen-Bonding Modified Conjugated Diene Hydrogen-Bonding Mw Mn Distribution (38° C.) Temperature Functional Groups Rubber Functional Group (× 10.sup.3) (× 10.sup.3) Mw/Mn (Pa .Math. s) (° C.) per molecule A-1 modified polyisoprene maleic anhydride group 34 30 1.13 198 −59 10 A-2 modified polyisoprene maleic anhydride group 13 11 1.18 23 −55 6 A-3 modified polybutadiene maleic anhydride group 29 27 1.07 95 −89 7 A-4 modified polybutadiene maleic anhydride group 47 41 1.15 828 −89 7 A-5 modified polybutadiene monomethyl maleate group 28 97 1.04 197 −88 7 A-6 modified polyfarnesene- monomethyl maleate group 67 52 1.28 926 −76 17 polybutadiene copolymer A-7 modified polyfarnesene- maleic anhydride group 103 81 1.27 1060 −73 32 polybutadiene copolymer

Example 1

[0219] As Example 1, reinforcing fibers having an adhesive component in at least a part of the surfaces of hydrophilic fibers were produced and evaluated as follows.

[0220] The modified conjugated diene rubber (A-1) produced as above was mixed with a mineral oil (purity 99.9% or more, flash point 158° C.) in a ratio of 3/7 to give an adhesive component. Using an oiling guide, the adhesive component was applied to PVA fibers (“Kuralon 1239” by Kuraray Co., Ltd., total fineness 1330 dtex, single fiber fineness 6.65 dtex) previously deoiled with acetone, and wound up. The PVA fibers to which the adhesive component had been adhered in that manner were twisted at a twisting number of 80 μm to give fiber cords.

Examples 2 to 11

[0221] Fiber cords were produced according to the same method as in Example 1 except that the adhesive component, the blending ratio of the conjugated diene rubber and the oil, and the deposition amount on the fibers were changed as in Table 2.

Examples 12 and 13

[0222] Fiber cords were produced according to the same method as in Example 1 except that the adhesive component, the blending ratio of the conjugated diene rubber and the oil, and the deposition amount on the fibers were changed as in Table 2, and further hydrophilized PVA fibers mentioned below was used as hydrophilic fibers.

Hydrophilization Treatment

[0223] Polyvinyl alcohol fibers (“Kuralon 1239” by Kuraray Co., Ltd., total fineness 1330 dtex, single fiber fineness 6.65 dtex) were clipped in an aqueous solution prepared to have the following composition, and then squeezed with. rollers. Next, the resultant, fibers were dried at 130° C. for 20 seconds, then further heat-treated at 240° C. for 20 seconds and rolled up to give hydrophilized PVA fibers.

[0224] Water: 96.96 parts by mass

[0225] Meikanate DM-3031 CONC: 22 parts by mass

[0226] Denacol EX-614B: 7 parts by mass

[0227] The hydrophilizing agent was prepared using a blocked isocyanate and an epoxy resin. As the blocked isocyanate, “Meikanate D1M-1-3031 CONC” by Meisei Chemical Works, Ltd. was used, and as the epoxy resin, “Denacol EX-614B” by Nagase ChemteX Corporation was used.

Comparative Example 1

[0228] Fiber cords were produced according to the same method as in Example 1 except that the mixture liquid was not adhered to the PVA fibers.

Comparative Example 2

[0229] 15 g of an emulsifier (polyoxyethylene alkyl (C=1.2 to 1.5) ether phosphate) (trade name “Phosphanol RS-710” from TOHO Chemical Industry Co., Ltd.) was added to 250 g of the modified conjugated diene rubber (A-1) and stirred for 20 minutes. Subsequently, with stirring, 180 g of an aqueous solution of 0.7 mol/L sodium hydroxide was added little by little. After a predetermined amount of water was added, this was stirred for 20 minutes to give an emulsion of the modified conjugated diene rubber (A-1). Water was further added to the emulsion so as to have a solid concentration of 9%, and then, using an oiling guide, this was applied to polyvinyl alcohol fibers (“Kuralon 1239” by Kuraray Co., Ltd., total fineness 1330 dtex, single fiber fineness 6.65 dtex) previously deoiled with acetone, then dried at 120° C. for 30 seconds, heat-treated at 170° C. for 30 seconds and wound up. The PVA fibers to which the adhesive component had been adhered in that manner were twisted at a twisting number of 80 Tim to give fiber cords.

Comparative Examples 3 to 5

[0230] Fiber cords were produced according to the same method as in Example 1 except that xylene, toluene or undecane was used in place of the mineral oil and the blending ratio of the conjugated diene rubber and the oil and the deposition amount on the fibers were changed as in Table 2.

Reference Examples 1 and 2

[0231] In Reference Examples 1 and 2, PVA fibers (“Kuralon 1239” by Kuraray Co., Ltd., total fineness 1.330 dtex, single fiber fineness 6.65 dtex) was subjected to known RFL treatment in such a manner that the deposition amount could be 2.0% by mass and 4.0% by mass, respectively, and then the fibers were twisted at a twisting number of 80 T/m to give fiber cords. The RFL liquid used here was prepared as follows.

[Composition of RFL Liquid]

Solution A

[0232] Water: 300 parts by mass

[0233] Resorcinol: 22 parts by mass

[0234] Formaldehyde (effective component 37% by mass): 33 parts by mass

[0235] Aqueous sodium hydroxide solution (effective component 10% by mass): 7 parts by mass

[0236] The solution A was aged at a temperature of 25° C. for 6 hours.

Solution B

[0237] SBR latex (effective component 40% by mass): 43 parts by mass

[0238] Vinylpyridine-modified SBR latex (effective component 40% by mass): 244 parts by mass

[0239] The solution B was mixed with the aged solution A, and aged at a temperature of 25° C. for 16 hours to produce an RFL liquid. For controlling the deposition amount on fibers, the liquid was diluted by twice with water after the above operation.

[0240] The vapor pressure at 20° C. of the mineral oil, the synthetic oil and the fatty acid ester was determined by calculating the constant A, the constant B and the constant C in an Antoine formula: log 10P=A.Math.(B/(T+C), based on the data measured by a gas flow method.

[0241] The vapor pressure at 20° C. of toluene and xylene was directly measured according to a quiescent technique.

[0242] The flash point of the mineral oil, the synthetic oil and the fatty acid ester was measured according to a Cleveland open-cup test method in JIS K 2265-4. The flash point of toluene, xylene and undecane was measured according to a tag closed test method in JIS K 2265-1.

[0243] The viscosity at 50° C. of the adhesive component was measured with a rotary B-type viscometer (rotation number 100 rpm) using a mixture previously heated at 50° C. in a water bath.

[0244] The deposition amount of the adhesive component was measured according to the following measurement method.

[0245] About 10 g of reinforcing fibers were taken as a sample, and the mass X thereof was measured. The adhesive component was extracted out from the sample, and the extracted mass .sup.V was measured. For extraction, toluene was used as a solvent, and the sample was extracted for 3 hours using a Soxhlet extractor. The deposition amount of the adhesive component was calculated according to the following expression.

Deposition amount of adhesive component (% by mass) on reinforcing fibers=(Y/X)×100

[0246] In addition, the content OA by mass) of the conjugated diene rubber in the adhesive component was calculated from the mass ratio of the conjugated diene rubber in the solid content in the adhesive component. The reinforcing fibers collected using a volatile oil were dried in air through a draft, and after the remaining oil evaporated away, the deposition amount was measured. Accordingly in the case, all the extracted oily component was a conjugated diene rubber.

[0247] In Examples 1 to 13, Comparative Examples 1 to 5, and Reference Examples 1 and 2, the mixture was applied to fibers in the manner as described in each example, and after 5 kg of the reinforcing fibers were wound up, the degree of contamination (gumming up) of holder rollers through which the reinforcing fibers had passed was determined according to the following evaluation standards.

Standards

[0248] G (good): There was no or little roller contamination by gumming up, and there was no problem in yarn-making operation.

[0249] P (poor): There was roller contamination by gumming up, and yarn-making operation was poor.

[0250] B (bad): There was remarkable roller contamination by gumming up, and during yarn-making, single yarns were taken over and insistently twined, and. there was a problem in yarn-making operation,

[0251] Reinforcing fibers were sampled, and stored at room temperature for 1 month, then the wear resistance thereof was evaluated according to the following method, Reinforcing fibers were twisted in the Z-direction at 80 t/m to form a ring, and at the center part of the ring, this was twisted three times in the S-direction, and while a load of 3 kg was applied thereto, the fibers were rubbed up and down at room temperature and the number of rubbing times before cutting was counted to evaluate the fibers according to the following evaluation standards.

[0252] G (good): The fibers were resistant to abrasion of 500 times or more, and. were excellent in process passage during working.

[0253] P (poor): The fibers were cut by abrasion of 100 times or more and less than 500 times, and were poor in process passage during working.

[0254] B (bad): The fibers were cut by abrasion of less than 100 times, and there was a problem in process passage during working,

[0255] The fiber cords produced in Examples 1 to 13, Comparative Examples 1 to 5, and Reference Examples 1. and 2 were formed into evaluation sheets according to the method described below. In the evaluation sheet, the fiber cord was peeled from the rubber in a mode of T-type peel, and the force (N/25.4 mm) needed for the peel was measured to be a rubber adhesion force. The results are shown in Table 2. Regarding the evaluation results of the rubber adhesion force, a larger value means a higher adhesion force between reinforcing fibers and rubber.

[0256] The evaluation sheets were produced as follows.

Production of Evaluation Sheet

[0257] The fiber cords produced in the above Examples, Comparative Examples and Reference Example were individually aligned and fixed on a masking tape like a bamboo curtain thereon in such a manner that the fiber cords could not overlap with each other. This was overlaid on an unvulcanized rubber composition containing EPDM rubber (“Esprene 501A” from Sumitomo Chemical. Co., Ltd.) as the main ingredient and prepared according to the formulation mentioned below using EPDM rubber (hereinafter this may also be referred to as “EPDM unvulcanized rubber”) (width 25.4 mm, length 240 mm). (The length of the overlapped part of the fiber cord and the EPDM unvulcanized rubber was 190 mm.) Next, this was vulcanized by pressing at 150° C. and under the pressure of 20 kg/cm.sup.2 for 30 minutes to produce an evaluation sheet.

(Blending Formulation of EPDM Unvulcanized Rubber)

[0258] EPDM rubber: 100 part by mass

[0259] Filler (carbon black): 60 parts by mass

[0260] Softening agent (paraffin-based process oil): 20 parts by mass

[0261] Crosslinking agent (sulfur powder): 1.5 parts by mass Vulcanization aid

[0262] (two kinds of zinc oxide, stearic acid): 6 parts by mass Vulcanization accelerator

[0263] (thiazole-based, thiuram-based): 1.5 parts by mass

TABLE-US-00002 TABLE 2 Adhesive Component Deposition Amount of Oil (O) Adhesive Component Conjugated 20° C. (% by mass) Diene vapor Flash 50° C. conjugated Rubber (R) pressure Point R/O viscosity diene Fibers kind kind (Pa) (° C.) volatility by mass (Pa .Math. s) total rubber oil Example 1 PVA fibers A-1 mineral oil 7.0 × 10.sup.−3 158 no 3:7 27.1 1.80 0.54 1.26 Example 2 PVA fibers A-1 mineral oil 7.0 × 10.sup.−3 158 no 1:9 2.7 2.10 0.21 1.89 Example 3 PVA fibers A-1 synthetic oil A 3.0 113 no 3:7 12.3 2.00 0.60 1.40 (*1) Example 4 PVA fibers A-1 mineral oil 1.1 × 10.sup.−3 222 no 3:7 81.0 1.40 0.42 0.98 Example 5 PVA fibers A-1 POE 1.7 × 10.sup.−3 258 no 3:7 63.2 1.30 0.39 0.91 (*2) Example 6 PVA fibers A-1 synthetic oil 3.6 × 10.sup.−3 255 no 3:7 82.5 1.30 0.36 0.94 (*3) Example 7 PVA fibers A-2 mineral oil 7.0 × 10.sup.−3 158 no 5:5 12.4 1.90 0.95 0.95 Example 8 PVA fibers A-2 mineral oil 7.0 × 10.sup.−3 158 no 7:3 93.2 1.40 0.98 0.42 Example 9 PVA fibers A-3 mineral oil 7.0 × 10.sup.−3 158 no 3:7 32.1 1.70 0.51 1.19 Example 10 PVA fibers A-4 mineral oil 7.0 × 10.sup.−3 158 no 2:8 65.3 1.56 0.30 1.26 Example 11 PVA fibers A-5 mineral oil 7.0 × 10.sup.−3 158 no 3:7 49.1 1.80 0.54 1.26 Example 12 hydrophilized A-6 POE 1.7 × 10.sup.−3 258 no 2:8 77.4 1.74 0.35 1.39 PVA fibers (*2) Example 13 hydrophilized A-7 POE 1.7 × 10.sup.−3 258 no 3:17 71.2 1.86 0.28 1.39 PVA fibers (*2) Comparative PVA fibers — — — — — — — — — — Example 1 Comparative PVA fibers — — — — — — 0.3 0.84 0.84 0.00 Example 2 Comparative PVA fibers A-1 xylene 8.0 × 10.sup.2 25 yes 3:7 4.5 0.55 0.55 0.00 Example 3 Comparative PVA fibers A-1 toluene 2.9 × 10.sup.2 4.4 yes 3:7 3.7 0.64 0.64 0.00 Example 4 Comparative PVA fibers A-1 undecane 6.0 × 10.sup. 60 yes 3:7 9.4 0.71 0.71 0.00 Example 5 Reference PVA fibers — — — — — — — 2.00 — — Example 1 (*4) Reference PVA fibers — — — — — — — 4.00 — — Example 2 (*4) Rubber Adhesion Degree of Force Process Weat (N/25.4 contamination Resistance mm) Example 1 G G 31.7 Example 2 G G 29.4 Example 3 G G 25.5 Example 4 G G 30.4 Example 5 G G 27.3 Example 6 G G 29.1 Example 7 G G 25.2 Example 8 G G 26.7 Example 9 G G 33.6 Example 10 G G 29.9 Example 11 G G 26.8 Example 12 G G 32.4 Example 13 G G 31.7 Comparative G G 8.8 Example 1 Comparative B B 21.4 Example 2 Comparative P B 18.4 Example 3 Comparative P B 19.0 Example 4 Comparative P P 24.3 Example 5 Reference — — 23.2 Example 1 Reference — — 28.9 Example 2 *1: 1-Tetradecene (Linealene 14 by Idemitsu Kosan Co., Ltd.) *2: Polyol fatty acid ester (trimethylolpropane tricaprylate) *3: Poly-α-olefin (FGC32 by Anderol Corporation) *4: Deposition amount of RFL

Example 14

[0264] Fiber cords were produced according to the same method as in Example 1 except that hydrophilized polyester fibers of PET fibers to be mentioned below were used as hydrophilic fibers.

Comparative Example 6

[0265] Fiber cords were produced according to the same method as in Comparative Example 1. except that hydrophilized polyester fibers of PET fibers to he mentioned below were used as hydrophilic fibers.

Reference Example 3

[0266] Fiber cords were produced according to the same method as in Reference Example 1. except that hydrophilized polyester fibers of PET fibers to be mentioned below were used as hydrophilic fibers.

[0267] Polyester fibers, PET fibers (“702C” by Toray Co., Ltd., total fineness 1670 dtex, single fiber fineness 5.80 dtex) were dipped in an aqueous solution prepared to have the following composition, and then squeezed with rollers. Next, the resultant fibers were dried at 130° C. for 60 seconds, then further heat-treated at 240° C. for 60 seconds and rolled up to give hydrophilized PET fibers.

[Composition of 1-lydrophilizing Agent]

[0268] Water: 96.96 parts by mass

[0269] Meikanate DM-3031 CONC: 22 parts by mass

[0270] Denacol EX-614B: 7 parts by mass

[0271] The hydrophilizing agent was prepared using a blocked isocyanate and an epoxy resin. As the blocked isocyanate, “Meikanate DM-3031 CONC” by Meisel Chemical Works, Ltd. was used, and as the epoxy resin, “Denacol EX-614B” by Nagase ChemteX Corporation was used.

[0272] The fiber cords produced in Example 14, Comparative Example 6 and Reference Example 3 were tested according to the same method as above to measure and evaluate the rubber adhesion force, except that an unvulcanized rubber composition mainly consisting of NR/SBR (hereinafter also referred to “unvulcanized NR/SBR rubber”) was used in place of the unvulcanized. EPDM rubber. The results are shown in Table 3.

[0273] Example 14, Comparative Example 6 and Reference Example 3 were evaluated for the degree of process contamination according to the same method as above. The results are shown in Table 3.

[0274] Example 14, Comparative Example 6 and Reference Example 3 were evaluated for the wear resistance according to the same method as above. The results are shown in Table 3.

TABLE-US-00003 TABLE 3 Adhesive Component Deposition Amount of Oil (O) Adhesive Component Conjugated 20° C. (% by mass) Diene vapor Flash 50° C. conjugated Rubber (R) pressure Point R/O viscosity diene Fibers kind kind (Pa) (° C.) volatility by mass (Pa .Math. s) total rubber oil Example 14 Hydrophilized A-1 mineral oil 1.7 × 10.sup.−3 158 no 2.5:7.5 27.1 1.80 0.45 1.35 PET Comparative Hydrophilized — — — — — — — — — — Example 6 PET Reference Hydrophilized — — — — — — — 4.00 — — Example 3 PET (*4) Rubber Adhesion Degree of Force Process Weat (N/25.4 contamination Resistance mm) Example 14 G G 130.8 Comparative G G 8.8 Example 6 Reference — — 91.4 Example 3 *4: Deposition amount of RFL

[0275] As obvious from the results of Examples and Comparative Examples, the reinforcing fibers of the present invention can be reinforcing fibers excellent in adhesiveness to rubber, without using an adhesive agent that contains a resorcinol-formaldehyde resin and a rubber latex as main ingredients. Also according to the present invention, reinforcing fibers can be produced efficiently while suppressing contamination of production facilities.

REINFORCING FIBER, METHOD FOR MANUFACTURING SAME, AND MOLDED BODY USING SAME

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