JPH09228251A - Polyvinyl alcohol fiber for hose reinforcement - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: Rubber reinforcing PV when using a breaking liquid
It greatly improves the durability of the A fiber, which improves the safety of the brake hose. A polyvinyl alcohol-based fiber for hose reinforcement, wherein a catechol derivative having a molecular weight of 120 or more is present in the fiber and / or on the surface of the fiber.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyvinyl alcohol fiber suitable for reinforcing high pressure resistant hoses such as hydraulic brake hoses of automobiles.

[0002]

2. Description of the Related Art A brake hose is composed of an inner tube rubber layer, a first fiber reinforcing layer, an intermediate rubber layer, a second reinforcing fiber layer, and an outer rubber layer, and is defined by JIS D-2601. As described above, various performances such as pressure resistance, non-expansion property, and durability are required. As the fiber reinforcing layer, two braid layers made of polyvinyl alcohol fiber (PVA fiber), rayon fiber, polyester fiber, aramid fiber, etc. are used. Since it is an important part that determines mechanical strength etc., extremely strict durability,
Pressure resistance is required.

The brake fluid is FMVSS No. 116
, There are DOT3 standard, DOT4 standard, DOT5 standard and DOT5.1 standard brake liquids (hereinafter simply referred to as DOT3 liquid, DOT4 liquid, DOT5 liquid).
Liquid, referred to as DOT5.1 liquid), and conventionally, DOT3 liquid (non-mineral oil-based brake liquid mainly containing glycols) has been widely used, but in recent years, it has a high boiling point and is more safe. The amount of DOT4 solution used as a brake solution is increasing. D
The OT4 liquid contains a boric acid ester compound in order to raise the boiling point, and the DOT5.1 liquid contains the boric acid ester compound as its main component.

The brake hose reinforced with polyvinyl alcohol fiber (PVA fiber) exhibits excellent pressure resistance, swelling resistance and durability under normal use conditions,
If the deterioration is forcibly promoted in the accelerated fatigue test at a high temperature, the break liquid may pass through the inner tube rubber to reach the fiber reinforcing layer and the fiber strength may be reduced. That is, when used under severe conditions, DOT4 liquid or DOT
When a breaking solution containing a large amount of boric acid ester such as the solution 5.1 reaches the fiber reinforcing layer, the boric acid ester having a strong electrophilic property acts on the hydroxyl group of the PVA molecule to disturb a part of the fiber structure. there is a possibility. From the above, the inventors of the present application have proposed to improve the durability, deterioration of mechanical performance, etc. by incorporating a boric acid scavenger such as catechol, fructose, and mannite into the fiber ( Japanese Patent Application No. 7-167188
issue).

[0005]

Among the boric acid scavengers, catechol, in particular, has a large effect of improving fatigue resistance and is superior in excellent characteristics, but has high volatility and sublimation property and is relatively short-term. There was a problem that the effect was lost in the meantime.
In view of the above problems, an object of the present invention is to provide a polyvinyl alcohol-based fiber for hose reinforcement having excellent fatigue resistance by maintaining a boric acid-trapping action for a long period of time.

[0006]

The present invention has a molecular weight of 120.
It is intended to provide a polyvinyl alcohol-based fiber for hose reinforcement, characterized in that the above catechol derivative is present in the fiber and / or on the fiber surface.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The structure of the catechol derivative used in the present invention is not particularly limited as long as it has a molecular weight of 120 or more, and it contains all substituents such as an alkyl group and an aryl group. Good. If the molecular weight becomes too large, P
The molecular weight of the catechol derivative is preferably 700 or less, more preferably 400 or less, because it is difficult for the catechol derivative to permeate into the VA. Among them, in addition to the hydroxyl group constituting the catechol,
Those having at least one functional group containing —OH are preferable, and particularly catechol derivatives having at least one methyl group (hydroxymethyl group), particularly 2 to 4 (hereinafter, simply referred to as a methyl group-containing catechol and (Referred to) can be preferably used. Of course,
A plurality of catechol derivatives which may have a substituent other than the methylol group and have different structures may be used.
Specific examples of such catechol derivatives include the compounds shown in Chemical formula 1.

[0008]

Embedded image

R1, R2 and R3 represent H or any substituent. Such a methyl group-containing catechol can be obtained, for example, by reacting and aging an aqueous solution of both catechol and formalin chemicals under an alkali or acid catalyst. The molar ratio of catechol / formalin is 10 /
It is preferably 1 to 1/30, particularly 5/1 to 1/10, and the pH of the reaction solution may be appropriately set. For example, when reacted under an acid catalyst, a novolac type addition condensate (b) mainly having extremely low volatility is obtained,
When the reaction is carried out under an alkaline catalyst, a resole type adduct (a) having no intermolecular crosslinks is mainly obtained. When reacted under an alkaline catalyst, the molecular weight is mainly 4
Since a catechol derivative having a molecular weight of 00 or less, particularly 300 or less can be obtained, it easily penetrates into PVA and fatigue resistance can be remarkably improved. Therefore, in order to fully express the boric acid trapping effect inside the fiber, the pH of the reaction solution should be adjusted to caustic soda.
It is preferable that the pH is adjusted to 8 to 10 with an alkali represented by DA, and it may be used in combination with a catechol derivative such as a novolac type addition condensate. Examples of the method for producing such a catechol derivative include a method in which a mixed aqueous solution of catechol, formalin and an alkali catalyst is aged at room temperature for 1 hour or more, particularly 5 to 15 hours.

The method for applying the catechol derivative is not particularly limited, and the method for applying the catechol derivative is, for example, a method for applying the catechol derivative, for example, adding a scavenger to the fiber raw material, applying it immediately after fiber spinning, or winding step after fiber spinning. And the like. Further, a method in which the reinforcing fiber is knitted into a hose and then applied, or a method in which it is applied to the surface or inside of the inner tube rubber or the outer rubber may be used. In the present invention, any of these methods may be used, or a plurality of methods may be combined. When the catechol derivative is applied, it may be applied as it is, or may be applied by dissolving it in an appropriate solvent. Further, the catechol derivative may be used by adding it to a dipping agent for adhesion treatment (RFL solution, epoxy treatment solution, rubber paste solution, isocyanate treatment solution, etc.). From the viewpoint of fiber durability, a method of directly applying an aqueous solution or the like to the fiber cord is preferable.

The larger the content of the catechol derivative, the greater the boric acid scavenging effect. However, if the scavenger is too much, the original performance of the fiber will be impaired and the adhesive force between the rubber and the fiber will be lowered. there is a possibility. Therefore, it is preferable to add the catechol derivative in an amount of 0.1 to 30% by weight, particularly 1 to 20% by weight based on the weight of the fiber. When the scavenger is directly added to the brake liquid, not only the boric acid around the fiber is hardly trapped, but also when it is mixed in a large amount, the performance of the brake liquid may be impaired. At this time, P
The retention rate of the catechol derivative when leaving the VA fiber in an atmosphere of 80 ° C. for 8 hours is preferably 40% or more, more preferably 60% or more, and particularly preferably 75% or more. If the retention rate is high, the volatility is low and the boric acid trapping effect can be obtained for a long time.

By using such a scavenger, it is possible to exhibit excellent performance such as a strength retention of 60% or more, particularly 80% or more in the durability test shown in the examples.
Even after the durability test, the strength can be increased to 10 kg or more, particularly 20 kg or more.

Any rubber compound containing 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 break hose can be obtained by integrally bonding the rubber layer and the reinforcing fiber layer. As described above, the PVA-based fiber for hose reinforcement of the present invention uses a brake liquid containing a large amount of a boric acid compound such as DOT4 liquid and DOT5.1 liquid, and even under extremely severe conditions, It exhibits excellent durability and can further improve the safety of the brake hose.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

【Example】

[Retention rate of catechol derivative (%)] PVA-based fiber a provided with catechol derivative and 80% of the fiber
Two types of hot-air treated yarns b, which were obtained by leaving them in a hot-air dryer at 8 ° C. for 8 hours, were prepared and their infrared absorption characteristics were measured using PAS (photoacoustic spectroscopy). About 1600 cm ^-1 and PVA derived from the skeletal vibration of the benzene ring of
The intensity ratio (A) and (B) of about 2950 cm ⁻¹ derived from the stretching motion of CH ₂ was measured, and the retention rate was calculated from (B) / (A) × 100, which was calculated as the catechol derivative. The retention rate was used. (A): Benzene ring vibration peak height of PVA fiber a /
CH ² vibration peak height (B): benzene ring vibration peak height of hot air treated yarn b / C
Click Height - vibration peak of H ²

[Code durability] JIS L-1017
It was measured by the Firestone method according to (Chemical fiber tire cord test method). The code density is 18 lines / 1 inch,
Spindle diameter 35 mm, load on the spindle 40
Bending treatment was performed 10,000 times at a test temperature of 100 ° C. and kgf. When the tensile strength of the cord before the test was A and the tensile strength after the treatment was B, the durability was calculated as (B / A) × 100.

[Examples 1 to 4] A catechol / formalin molar ratio of 1/1 was added to an aqueous solution having a catechol concentration of 10% by weight.
Formalin is added so that
A caustic soda mixed aqueous solution (pH 9) was added so as to be 4 parts by weight with respect to 00 parts by weight, and as shown in Table 1, at 0 ° C. at 0 ° C.
Aged for 100 hours to prepare a treatment liquid. On the other hand, the PVA-based fiber is a vinylon filament yarn that has been spun, drawn and heat treated (Kuraray Co., Ltd., product number 1239: 120).
0d / 200f) and using the above treatment liquid as a bath liquid
After picking up with a latouch type processing machine and adhering it by 60% by weight, a roller at 100 ° C. was touched and dried to treat (catechol derivative adhesion rate 10.2% by weight).

The retention rate of the catechol / formalin addition condensate (catechol derivative) was measured by the method of leaving the treated yarn in the atmosphere at 80 ° C. as described above. The treated yarn was given a ply twist in the z direction 28 times per 10 cm, and further, 3 s of these yarns were combined and 28 times s per 10 cm.
A twist was applied in the direction to obtain a cord. Then R of the following composition
After dipping in FL solution and drying at 100 ° C for 2 minutes, 160
Heat treatment was carried out at ℃ for 2 minutes to obtain an adhesion-treated code.

(RFL Solution Composition) Solution A Water 300 parts Resorcin 11 parts Formaldehyde (37%) 24 parts Sodium hydroxide aqueous solution (10%) 11 parts The above solution A was aged at a temperature of 25 ° C. for 6 hours. Solution B SBR latex 130 parts Vinylpyridine-modified SBR latex 130 parts Water 260 parts The solution B was mixed with the aged solution A and then aged at a temperature of 25 ° C. for 16 hours.

In measuring the durability of the obtained cord, assuming penetration of the brake liquid in an actual hose,
The following pretreatment was performed. The cord was dipped in a brake solution (HONDA genuine DOT4 solution 2.1% by weight boric acid) at 25 ° C for 24 hours, squeezed so that the amount of the adhered brake solution was 30%, and 24 at 100 ° C. Heat treated for hours. The results are shown in Table 1.

[Examples 5 to 10] The same procedure as in Example 1 was carried out except that the catechol / formalin molar ratio was changed and the aging time was changed to 10 hours. Table 2 shows the results.

[0022]

[Table 1]

[0023]

[Table 2]

[Example 11] The catechol / formalin condensate-adhered yarn of Example 3 was subjected to a known RFL treatment so that the adhering rate was 3%. This treated yarn and rubber (SBR)
Using an inner diameter of 6.3 mmφ, 10.4
The first-layer reinforcing yarn (1200d / 2/2 × 24 carrier) in the mmφ portion, and the second-layer reinforcing yarn (1200 in the 12.8mmφ portion.
d // 3 × 24 carrier-) outer diameter 15.5 mmφ
The hoses were created. This hose is cut into 40 cm, and metal fittings are attached to both ends of the hose to make it a genuine Honda bracelet.
Fill the liquid DOT-4, 0-100kgf at 100 ℃
/ Cm ² of pressure was applied impulsively at a frequency of 70 times / minute, and the number of impulses until breakage of the hose and leakage of the brake fluid was measured. As a result, the liquid did not leak even after 30,000 times.

[0025]

According to the present invention, DOT-4 liquid, DOT
Even when a breaking solution containing a large amount of a boric acid compound such as -5.1 solution is used, the durability of the PVA-based fiber can be significantly improved, and its effect can be obtained for a long period of time. .

[Brief description of drawings]

The schematic diagram which showed one example of the hose obtained using the PVA type | system | group fiber for reinforcement of this invention.

[Explanation of symbols]

 1: Inner layer rubber layer 2: First layer fiber reinforcement layer 3: Intermediate rubber layer 4: Second layer fiber reinforcement layer 5: Outer layer rubber layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichiro Hanamori 1-2-1 Kaigandori, Okayama-shi Kuraray Co., Ltd.

Claims (2)

[Claims] 1. A polyvinyl alcohol-based fiber for hose reinforcement, characterized in that a catechol derivative having a molecular weight of 120 or more is present in the fiber and / or on the surface of the fiber. 2. A polyvinyl alcohol for hose reinforcement, characterized in that a catechol derivative having a methylol group and a molecular weight of 140 or more is present in the fiber and / or on the surface of the fiber.
Le fiber. [0001]