JP6196577B2 - Dip cord for rubber reinforcement and method for manufacturing the same - Google Patents

Description

  The present invention relates to a polyvinyl alcohol fiber dip cord having improved reinforcement, adhesion and liquid leakage resistance (leakage resistance), which is used as a rubber reinforcing material for rubber products such as hoses, and a method for producing the same.

  A cord used as a rubber reinforcing material such as a hose is required to provide a hose that is excellent in reinforcing property, has good adhesion to rubber, and has liquid leakage resistance. For this reason, in order to ensure adhesiveness with rubber, before being laminated with rubber, the cord was previously subjected to a resorcin / formalin latex (hereinafter sometimes abbreviated as RFL) treatment and an RFL treatment. The code is called a dip code.

  The RFL processing is disclosed in Patent Document 1 as follows. Conventionally, the pretreatment was performed so that the solid content of the isocyanate compound or the epoxy compound was 0.5 to 2.0% by mass as the first stage treatment, and the hydrogenated nitrile rubber latex or NBR latex as the second stage treatment. Is treated with an RFL solution containing the component, and the porosity of the cord after the treatment is set to 0 to 1.5%, thereby reducing the first-stage solid content adhesion amount and reducing the cord porosity. The liquid is filled as much as possible. That is, the amount of solid content in the first stage is reduced, the cord hardness is suppressed to improve the bending fatigue resistance, and the RFL liquid is filled as much as possible to reduce the porosity of the cord, thereby converging the filament group. Improves hot properties and improves adhesiveness.

  In Patent Document 2, it is desirable that the cross-sectional porosity of the cross section of the cord is 10% or less, preferably 8% or less, more preferably 6% or less, and the cord porosity is 10%. Exceeding the range, stress transmission within the cord may be uneven, and the carbon fiber single yarns are likely to be rubbed together, resulting in a lack of fatigue resistance as a result. .

JP-A-9-158989 JP 2006-183203 A

An object of the present invention is to obtain a fiber cord reinforced rubber hose (brake hose, etc.) reinforced with polyvinyl alcohol fiber, which has excellent strength properties and excellent liquid leakage resistance, and is used for such a rubber hose RFL. To get the processed dip code.
As shown in Patent Document 1 and Patent Document 2 described above, conventionally, with respect to the RFL processing of the cord, the RFL treatment is performed so that the cord is filled with the RFL liquid as much as possible to reduce the porosity inside the cord. It has been desirable to do so.
The inventors of the present invention need only perform the RFL treatment performed to ensure adhesion with the rubber only on the surface layer of the cord that comes into contact with the rubber. The inventors have found that the movement of the constituent fibers is constrained and negatively affects the reinforcing effect of the fibers, and the present invention has been achieved.

In the first configuration of the present invention, a cord composed of at least 200 polyvinyl alcohol filament single yarns and a yarn comprising a single yarn in the range of 20 to 100 T / m of twist or a plurality of the yarns are combined. A dip cord composed of a cord and an RFL (resorcin / formalin latex) RFL resin adhering to the cord in an amount of 2 to 15 mass% per fiber weight,
The cord is composed of a surface layer and an inner layer, and
The porosity in the cord cross section is in the range of 20% to 50%,
In the dip cord, the RFL resin is unevenly distributed in the vicinity of the cord surface layer, and the gap in the cross section is unevenly distributed between single filaments constituting the inner layer of the cord.

  The cross section of the cord preferably has a flat shape in which the ratio of the major axis to the minor axis (major axis / minor axis) is in the range of 1.5 to 5.0.

The above dip cord increases the ratio of resorcin to formalin as the composition of the RFL solution, and passes the cord through an immersion trough containing the RFL treatment solution under high tension (400 to 1000 mg / dtex). Without penetrating the inside of the cord, it is possible to obtain a dip cord in which the RFL resin adheres mainly to the cord surface layer.

The second configuration of the present invention is a cord composed of at least 200 polyvinyl alcohol filament single yarns, wherein a yarn having a twist number in the range of 20 to 100 T / m is left as it is or a cord in which a plurality of the yarns are combined. Then, it is introduced into an RFL (resorcin / formalin latex) treatment liquid tank that satisfies the following requirements (a) and (b), a tension of 400 to 1000 mg / dtex is applied, and the treatment liquid is impregnated and passed through. A method for producing a dip cord, wherein RFL treatment is performed and 2 to 15% by mass of RFL resin is adhered per fiber weight.
(A) The ratio of R (resorcin) to F (formalin) is in the range of 1.5 / 3 to 3/1 (molar ratio).
(B) The ratio of RF (resorcin / formalin) / L (latex) is in the range of 1/3 to 1/7 (weight ratio).

  The latex of the RFL treatment liquid is preferably styrene / butadiene copolymer latex and / or vinylpyridine / styrene / butadiene copolymer latex.

In the dip cord according to the first configuration of the present invention, the RFL resin is unevenly distributed on the surface of the cord, and the gap is unevenly distributed between the filament single yarns of the inner layer of the cord. On the other hand, since there is a gap between the filament single yarns of the inner layer of the cord, the mechanical properties of the polyvinyl alcohol filament single yarns are not constrained because the filament single yarns of the inner layer are not constrained Is effective as a dip cord for rubber reinforcement used in brake hoses and the like.
In particular, according to the present invention, a cord can be produced from a filament yarn having a small number of twists. Therefore, the mechanical properties of the filament yarn are easily utilized, and the adhesion rate of the RFL resin is 2 to 15% by mass (vs. The low weight of the filament fiber) makes it easy to take advantage of the properties of the filament yarn. Moreover, in the preferable aspect of this invention, since the major axis / minor axis ratio in the cross section of the cord after RFL treatment is in the range of 1.5 to 5.0 and the cord cross section has a flat shape, Thinning of the fiber reinforcement layer is achieved in rubber products.

According to the method for manufacturing a dip cord according to the second configuration of the present invention, as the RFL treatment liquid, R
A treatment solution having a ratio of F to 1.5 / 1 to 3/1 (molar ratio) and an RF / L ratio of 1/3 to 1/7, particularly a treatment solution having a high ratio of resorcin to formalin. By using it, the RFL resin can be unevenly distributed on the surface of the filament cord. In particular, when the cord is immersed in the RFL treatment liquid, it is effective to apply a high tension to the cord so that the RFL treatment liquid does not penetrate into the inner layer of the cord.

It is explanatory drawing which shows the cross-section of the conventional dip cord. It is explanatory drawing which shows the cross-section of the dip cord which concerns on this invention. It is a cross-sectional photograph which shows an example of the dip code | cord | chord which concerns on this invention. It is a cross-sectional photograph which shows an example of the conventional polyester fiber cord. It is explanatory drawing which shows the outline | summary of a RFL processing apparatus.

  The dip cord of the present invention is an RFL made of a cord composed of at least 200 polyvinyl alcohol filament single yarns, with a yarn in the range of 20 to 100 T / m as it is, or a cord in which a plurality of the yarns are combined. Manufactured by processing.

(Polyvinyl alcohol filament)
As a polyvinyl alcohol filament used in the present invention, a viscosity average polymerization degree of 1000 to 4000, preferably 1500 to 3500, a polyvinyl alcohol flake having a saponification degree of 99 mol% or more as an aqueous solution having a concentration of 15 to 45%, a dry type, Examples include those produced by spinning by a wet or dry-wet method, performing dry heat stretching (for example, stretching ratio: 6 to 10 times), and further subjecting to formalization in some cases. As the single fiber fineness of the polyvinyl alcohol filament, those within the range of 1 to 100 dtex are used, and yarns having a total fineness of 500 to 3000 dtex formed from at least 200 single yarns are used. This yarn is subjected to a twist of 20 to 100 T / m per m. If the number of twists is too small, the yarn tends to “break apart” and the process passability tends to be insufficient. If the number of twists is too large, the utilization factor of strength decreases, and the polyvinyl alcohol filament It tends to be impossible to fully exhibit the strength characteristics.
In the present invention, the polyvinyl alcohol-based filament may be processed as described above by RFL (resorcin / formalin latex) treatment to form a dip cord, and a plurality of (for example, 2 to 6) yarns or yarns The dip code may be formed by performing RFL processing on the formed code. In the case of a polyvinyl alcohol filament, it is preferable to set the number of twists of the cord subjected to the RFL treatment to be small from the viewpoint of increasing the utilization factor of strength.

(RFL composition)
When a hose is manufactured by reinforcing a rubber using a polyvinyl alcohol filament cord, the RFL treatment performed to ensure the adhesion between the filament and the rubber may be performed on the surface of the cord in contact with the rubber. It is preferable that the filament in the inner layer is not restrained by the RFL resin in view of the mechanical properties of the filament forming the cord. The present inventor has studied the RFL processing from this viewpoint. As a result, the inventors have found that the following RFL resin composition is effective.
(1) R (resorcin) / F (formalin): 1.5 / 1 to 3/1 (molar ratio)
(2) RF (resorcin / formalin) / L (latex): 1/3 to 1/7 (weight ratio)

The above RFL composition has a higher ratio of resorcin to formalin than a normal composition. By increasing the ratio of resorcin, the curing of the RF resin proceeds faster and the resin tends to adhere to the surface of the cord than inside the cord.
In this invention, the adhesion amount of RFL resin exists in the range of 2-15 mass% with respect to the filament cord weight. If the amount of adhesion is too small, the adhesion to the rubber will be insufficient, and if the amount of adhesion is too large, the resin will easily enter the inside of the cord, and the movement of the filament forming the cord will be constrained and the mechanical strength will not be exhibited. It becomes easy to be done.

  The rubber latex used in resorcin / formalin latex is natural rubber latex, styrene / butadiene rubber latex, acrylonitrile / butadiene rubber latex, chloroprene rubber latex, vinylpyridine / styrene / butadiene rubber latex, ethylene / propylene / non-propylene latex. Examples thereof include conjugated diene terpolymer rubber latexes, and these can be used alone or in combination. Of these, styrene / butadiene rubber latex and vinylpyridine / styrene / butadiene terpolymer rubber latex are preferable.

(RFL treatment)
The RFL treatment of the polyvinyl alcohol filament cord is usually performed using the apparatus shown in FIG. The cord pulled out from the crill stand is introduced into the RFL treatment solution tank, immersed in the RFL treatment solution, and a predetermined amount (2 to 15% by mass per weight of the fiber cord) of RFL resin is adhered to the drying device, followed by heat treatment. It is introduced into the device, dried and heat-treated, and wound on a winding device (bobbin). In the present invention, the cord is subjected to RFL treatment under high tension so that the filament on the surface layer of the cord is subjected to RFL treatment as much as possible, that is, the penetration of the treatment liquid into the cord is prevented. The tension applied to the cord is within the range of 400 to 1000 mg / dtex, more preferably within the range of 450 to 750 mg / dtex, thereby preventing the RFL resin from penetrating into the cord. A dip code unevenly distributed in the layer can be obtained. In the cords shown in the prior art (see Patent Literature 1 and Patent Literature 2), as shown in FIG. 1, the fiber cord is impregnated with RFL resin, but in the present invention, as shown in FIG. The RFL resin is unevenly distributed in the cord surface layer. In the present invention, the vicinity of the cord surface layer refers to a group of 1 to 3 filament single yarns forming the cord surface as shown in FIG. 2, and the inner side is the inner cord layer.

(Dip code)
In the dip cord of the present invention that has been RFL-treated, 2 to 15% by mass of RFL resin is attached to the cord with respect to the fiber weight, and the distribution thereof is unevenly distributed near the cord surface layer. Therefore, the cord inner layer is less likely to penetrate the RFL resin, and as a result, there is not much resin between the filaments constituting the cord, and a gap is formed between the filament single yarns. For this reason, in the dip cord of the present invention, the porosity is in the range of 20 to 50%, preferably in the range of 25 to 45%. If the porosity is too low, the RFL resin tends to penetrate into the inside of the cord and restrain the movement between the filament fibers to prevent the fiber from exhibiting its mechanical strength. It tends to be formed and tends to have insufficient adhesion to rubber.

  The dip cord having a flat cross-sectional shape is advantageous in terms of air leakage because the rubber layer containing the reinforcing fibers becomes thinner. A flat structure can be obtained by increasing the length of the major axis to the length of the minor axis of the dip cord of the polyvinyl alcohol filament by 1.5 to 5 times. Such a flat structure can be obtained by appropriately pressing at the time of drying after the RFL treatment because the adhesion amount of the RFL resin is smaller than that in the case of the normal RFL treatment in the present invention.

(Rubber reinforcement)
The dip cord of the present invention is used for rubber reinforcement, and is particularly useful as a reinforcing material for hoses, particularly brake hoses.
Any rubber compound including styrene / butadiene rubber, chloroprene rubber, ethylene / propylene rubber, nitrile rubber and the like can be used for the inner rubber layer and the outer rubber layer constituting the brake hose. An excellent brake hose can be obtained by integrating the rubber layer with the reinforcing fiber layer.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not limited at all by these Examples.

(Measurement of porosity)
A dip cord (number of single yarns: 200) is cut, photographed with an optical microscope, and enlarged. From the magnified image, an average fiber and a void portion (the number of single fibers is 10) are cut out, and the weight of the single yarn and the void is measured to obtain the cross-sectional area (including void) (Wc) of the dip cord.
In addition, 10 single yarns were cut out from the above image, weighed, converted to the number of cord fibers (200) (20 times), the total cross-sectional area (Wf) of the single yarn was obtained, and the porosity was calculated by the following formula: calculate.
Porosity (%) = (Wc−Wf) / Wc × 100
Wc: Dip cord cross-sectional area (including voids)
Wf: Total area of single yarn (average cross-sectional area of single yarn x number of components)

(Measurement of RFL adhesion)
The RFL adhesion rate dip cord was treated with concentrated HCl to dissolve the PVA fiber, and the RFL solution adhesion rate was calculated from the weight of the undissolved material.

(Measurement of air leak)
A hose reinforcing fiber cord is placed between two rubber plates so that the two cords cross each other, press vulcanized at 160 ° C for 30 minutes, and the length of the cord is 5 cm (longitudinal) 1 cm × 1 cm wide × 7 cm long). The measurement piece is allowed to stand at room temperature so that a constant air pressure can be applied to one end surface where the cord end surface of the measurement piece is exposed, and the air permeability that allows the other end surface to permeate through the cord is improved. In this method, the moving distance of the water surface when the air pressure was gradually increased from 0.1 to 0.3 MPa over 10 minutes was measured, and the average value was calculated.

(Measurement of adhesive strength)
It shows the adhesive strength between the processing cord and rubber. Five cords were buried near the surface of the rubber sheet, vulcanized under pressure at 150 ° C. for 30 minutes, and then the force required to peel the three cords from the rubber sheet was N / 3. Measured with a book and indexed.

(Comprehensive evaluation)
From the dip cord air leak, adhesive strength, mechanical properties (mainly handling properties), it was comprehensively judged according to the following criteria.
○: All of the above three items satisfy the required performance as a dip code.
X: At least one of the above three items does not satisfy the required performance as a dip code.

(Example 1)
A polyvinyl alcohol filament yarn (Kuraray Co., Ltd. vinylon filament, product number 1239, 1330 dtex / 200f) was twisted 45 times per meter. Using this yarn as a cord as it is, it was immersed in an RFL treatment liquid having the following composition under a tension of 700 mg / dtex, and squeezed so that the adhesion rate of the RFL solid content was 5 mass% per fiber weight,
The film was dried at 100 ° C. for 2 minutes, and then heat treated (cured) at 160 ° C. for 2 minutes to prepare a dip cord. The performance measurement results of the obtained dip code are shown in Table 1.

(RFL solution composition)
The RFL solution (R / F = 2; RF / L = 0.23) was adjusted as follows.
Liquid A: 300 parts of water, 22 parts of resorcin, 8 parts of formaldehyde (37%) and 11 parts of aqueous sodium hydroxide (10%) were blended and aged at 25 ° C. for 6 hours to prepare liquid A.
Liquid B: 130 parts of SBR latex, 130 parts of vinylpyridine-modified SBR latex, and 260 parts of water (latex is 40% solids and 260 parts in water) and mixed with aged A liquid Thereafter, aging was performed at a temperature of 25 ° C. for 16 hours.
The RFL solution (R / F = 3; RF / L = 0.29) was adjusted as follows.
Liquid A: 300 parts of water, 33 parts of resorcin, 8 parts of formaldehyde (37%), and 11 parts of aqueous sodium hydroxide (10%) were blended and aged at 25 ° C. for 6 hours to prepare liquid A.
Liquid B: 130 parts of SBR latex, 130 parts of vinylpyridine-modified SBR latex, and 260 parts of water (latex is 40% solids and 260 parts in water) and mixed with aged A liquid Thereafter, aging was performed at a temperature of 25 ° C. for 16 hours.

(Example 2)
A dip cord was produced under the same RFL operating conditions (draft, drying / heat treatment temperature / time) as in Example 1 except that the adhesion rate of the RFL resin was changed to 2% by mass. The performance measurement results of the obtained dip code are shown in Table 1.

(Example 3)
Dip code was prepared under the same RFL operating conditions (draft, drying, heat treatment temperature, time) as in Example 1 except that the resorcin ratio with respect to formalin in the RFL liquid composition was 3 and the adhesion rate of the RFL resin was 10% by mass. did. The performance measurement results of the obtained dip code are shown in Table 1.

Example 4
It carried out like Example 1 except the number of twists having been 90 T / m. The performance measurement results of the obtained dip code are shown in Table 1.

(Example 5)
Dip code was prepared under the same RFL operating conditions (draft, drying, heat treatment temperature, time) as in Example 1 except that the resorcin ratio with respect to formalin in the RFL liquid composition was 3 and the adhesion rate of the RFL resin was 15% by mass. did. Due to the high RFL adhesion rate, the porosity decreased slightly. The performance measurement results of the obtained dip code are shown in Table 1.

(Example 6)
A dip cord was prepared under the same RFL operating conditions (draft, drying / heat treatment temperature / time) as in Example 1 except that the ratio of resorcin to formalin was 3 in the RFL liquid composition. The performance measurement results of the obtained dip code are shown in Table 1.

(Comparative Example 1)
The same procedure as in Example 1 was performed except that the sample was immersed in the RFL treatment solution under a tension of 300 mg / dtex. The performance measurement results of the obtained dip code are shown in Table 1.

(Comparative Example 2)
The same procedure as in Example 1 was performed except that the number of twists was 150 T / m. The performance measurement results of the obtained dip code are shown in Table 1.

(Comparative Example 3)
The same operation as in Example 1 was conducted except that the RFL adhesion amount was 1%. The performance measurement results of the obtained dip code are shown in Table 1.

(Comparative Example 4)
The same procedure as in Example 1 was performed except that the RFL adhesion amount was 20%. The performance measurement results of the obtained dip code are shown in Table 1. Since the amount of RFL adhered was large, the dip cord was extremely stuck and difficult to handle.

(Dip code cross section)
A cross-sectional photograph of the dip cord of Example 1 is shown in FIG. From the cross-sectional photograph, in the dip cord according to the present invention, the RFL resin is adhered so that there is substantially no gap between the filament single yarns in the vicinity of the surface layer, but in the inner layer, between the filament single yarns. The presence of voids can be observed.
On the other hand, a cross-sectional photograph of a commercially available polyester fiber dip cord is shown in FIG. 4. In this case, the entire cross-section, that is, all the fibers constituting the cord are bonded by the RFL resin, so that there are substantially voids. You can see that it is not.
In the present invention, as described above, the RFL resin is unevenly distributed on the surface of the cord, and the resin is not sufficiently permeated into the inner layer of the cord, so that the gap is unevenly distributed. Gives a fiber reinforced rubber product (brake hose, etc.) with excellent performance.

  Since the dip cord for rubber reinforcement according to the present invention is suitable for rubber reinforcement, particularly for brake hose reinforcement, it has industrial applicability.

  Although the preferred embodiments of the present invention have been described above by way of example, those skilled in the art can make various modifications, additions and substitutions without departing from the scope and spirit of the present invention disclosed in the claims. It will be understandable.

Claims (4)

A cord composed of at least 200 polyvinyl alcohol filament single yarns, a cord consisting of a single yarn within a range of twists of 20 to 100 T / m, or a cord in which a plurality of the yarns are combined, and the cord A dip cord composed of RFL (resorcin / formalin latex) resin adhering to 2 to 15% by mass per fiber weight,
The cord is composed of a surface layer and an inner layer, and
The porosity in the cord cross section is in the range of 20% to 50%,
The RFL resin is unevenly distributed in the vicinity of the cord surface layer, and the gap in the cross section is unevenly distributed between single filaments constituting the inner layer of the cord.   2. The dip cord according to claim 1, wherein a cross section of the cord has a ratio of a major axis to a minor axis (major axis / minor axis) in a range of 1.5 to 5.0 and has a flat shape. A cord composed of at least 200 polyvinyl alcohol filament single yarns having a twist number in the range of 20 to 100 T / m is used as it is or a cord in which a plurality of the yarns are combined is used in the following (a) and (b ) Which satisfies the requirements of (1), is introduced into a treatment liquid tank of RFL (resorcin / formalin latex), applied with a tension of 400 to 1000 mg / dtex, impregnated and passed through the treatment liquid, and subjected to RFL treatment. A method for producing a dip cord, wherein 2 to 15% by mass per fiber weight is adhered.
(A) The ratio of R (resorcin) to F (formalin) is in the range of 1.5 / 1 to 3/1 (molar ratio).
(B) The ratio of RF (resorcin / formalin) / L (latex) is in the range of 1/3 to 1/7 (weight ratio).   The dip cord manufacturing method according to claim 3, wherein the latex of the RFL treatment liquid is a styrene / butadiene copolymer latex and / or a vinylpyridine / styrene / butadiene copolymer latex.

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