JPH0516295A - Hose - Google Patents

Abstract

PURPOSE:To manufacture a hose of superior resistance to hot water and resistance to fatigue using polyvinyl alcohol fiber as a reinforcing material by making use of the characteristics of polyvinyl alcohol such as high strength, low extensibility and high elasticity. CONSTITUTION:Polyvinyl alcohol fiber satisfying the following conditions (a), (b) and (c) is used as a reinforcing material for a hose. The conditions are (a) the tensile strength of fiber is 12g/d or over, (b) the tensile strength residual percentage is 80% or more after leaving in hot water of 150 deg.C in the given length for 60 minutes and (c) the initial elasticity is lX10<-3>g/d or more after leaving in hot water of 180 deg.C for 60 minutes under no tension.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a polyvinyl alcohol fiber having high strength and excellent resistance to hot water (hereinafter referred to as P
(Hereinafter abbreviated as VA fiber), which relates to a hose reinforced by a VA fiber, particularly for a water hose for an automobile which has been difficult to practically use a conventional PVA fiber, and for an automobile having improved durability in response to a request for longer life. It relates to an oil brake hose.

[0002]

2. Description of the Related Art PVA fiber has the characteristics of high strength, low elongation, and high elasticity, and is widely used as a hose reinforcing material. Oxygen / acetylene hose, air hose, agricultural spray hose, hydraulic hose. The application fields are wide, from rubber hoses for car coolers, freon hoses for automobiles, fuel hoses for automobiles, oil brake hoses for automobiles, to resin hoses made of PVC or nylon.

However, in a water hose for automobiles (JIS-D-2602), which is a radiator hose for automobiles and a heater hose for heating automobiles, the liquid flowing in the hose is an antifreezing liquid containing hot water as a main component. Since hot water resistance is required, conventional hoses made of PVA fiber as a reinforcing material are not suitable for this type of application. This is because there is no problem in a normal state where the fibers are covered with rubber, but when the rubber has a pinhole or a crack, it is expected that the PVA fibers will be deteriorated by the intrusion of hot water.

Although the radiator liquid is normally controlled to be around 80 ° C., the hose itself reaches around 120 ° C. due to radiant heat from the engine. However, conventional PVA fibers are not suitable for use in this application because they dissolve in hot water at 120 ° C.

The oil brake hose is a field in which PVA fiber is already used, and there is no problem at present, but there is a strong demand for improvement in durability with the prolongation of life.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to make a hose of stable quality by utilizing the characteristics of PVA fiber by using PVA fiber whose hot water resistance is improved to 150 ° C. or higher. Further, it is to efficiently manufacture a water hose for automobiles, which cannot be made with a conventional PVA fiber, by utilizing high strength.

[0007]

Means for Solving the Problems The present inventor diligently studied the above problems, and obtained PVA fibers having high strength and improved hot water resistance as described below, and a hose using the fibers as a reinforcing material solves the above problems. I knew it would be possible. That is, the present invention provides a hose using a polyvinyl alcohol fiber satisfying the following conditions (a), (b) and (c) as a reinforcing material. (A) The fiber has a tensile strength of 12 g / d or more. (B) The residual rate of tensile strength after standing for 60 minutes in hot water at 150 ° C for a fixed length is 80% or more (c) After standing for 60 minutes in hot water at 180 ° C without tension. The initial elastic modulus is 1 × 10 ⁻³ g / d or more.
It consists of.

Various attempts have been made to crosslink the polymer constituting the PVA fiber in order to increase the resistance of the PVA fiber to hot water, and aldehydes, epoxies, isocyanates, peroxides, etc. are effective. Is known to be.

However, all of these crosslinking reactions are PV
It is necessary for the cross-linking agent to enter the inside of the A fiber, and the strength of the fiber will decrease if the agent is forced to enter. The strength of the fiber is developed by the oriented crystallization of the polymer by the drawing operation, but in order to carry out the crosslinking without adversely affecting the drawing operation, it is necessary to carry out the reaction after the drawing. However, since the molecules are oriented and crystallized, it takes a long time for the treatment because of the internal penetration of the drug. Therefore, it is preferable to perform the chemical treatment before the fibers crystallize. However, if a cross-linking reaction occurs before stretching, the stretchability deteriorates and the fiber does not have high strength.

To solve this problem, Japanese Patent Laid-Open No. 1-156
PV partially stretched in advance as seen in No. 517
Attempts have been made to treat the A fibers with a crosslinking agent, and then draw the fibers. However, pre-stretching is unnecessary from the internal penetration of the drug.

Therefore, this problem is basically solved by finding a drug which does not undergo crosslinking during the stretching operation, but which undergoes subsequent heat treatment. It has been found that the drug is an inorganic acid, and phosphoric acids are particularly preferable.

The phosphoric acid is typically orthophosphoric acid, and may be metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid and salts thereof. Further, it may be an ammonium salt of phosphoric acid or a derivative of phosphoric acid which generates phosphoric acid by heating. Phosphoric acids play a catalytic role in the cross-linking reaction, not in the sequestration of hydroxyl groups that bind to hydroxyl groups. If phosphoric acid reacts with a hydroxyl group and has an ether bond, it is easily hydrolyzed by an alkali, but this crosslinking reaction is not hydrolyzed. The amount of phosphoric acid used is 2 with respect to PVA.
%, Which is a trace amount or less, and is effective in the amount of catalyst.

Since it is effective in the presence of a catalytic amount of phosphoric acid, even if the yarn is treated with the phosphoric acid before its dry hot drawing, it is possible to obtain a high draw ratio (for example, a total draw ratio of 17
It is possible to obtain a PVA fiber having a high strength, that is, a draw strength (for example, more than double). Also, since the crosslinking reaction begins to occur near the stretching temperature of 240 ° C.,
By rapidly performing super-stretching, the stretching can precede the crosslinking reaction.

By adding a treatment with phosphoric acids in the known production process of high-strength PVA fibers,
The resulting PVA fiber has a slight decrease in strength due to treatment,
Holds a strength of 12 g / d or more and has an initial elastic modulus of 250 g.
A value of / d or more can be easily obtained. Moreover, the hot water resistance of the PVA fiber obtained by the treatment with this phosphoric acid is 150.
The retention rate of the dry strength after leaving the fiber under constant length for 60 minutes in water in an autoclave at ℃ can be 80% or more.

The higher the degree of crosslinking, the better the hot water resistance. Although it is difficult to evaluate the degree of cross-linking, rubber evaluates the degree by the elastic modulus. Therefore, in the present invention, the yarn is evaluated as a gel-like elastic fiber. That is, the sample fiber is placed in hot water of 180 ° C. without tension 6
Since it becomes a rubber-like elastic fiber when left for about 0 minutes, it is obtained by measuring the initial elastic modulus of the fiber after standing for 60 minutes under this condition, and this initial elastic modulus is 1 × 10 ⁻³ g /
If the fiber is crosslinked so as to be d or more, the desired hose can be obtained by satisfying the above fiber strength and hot water resistance. The degree of cross-linking varies depending on the degree of polymerization of polyvinyl alcohol and the internal structure even under the same cross-linking treatment conditions, and naturally also varies depending on the cross-linking treatment conditions. Therefore, consequently, it is necessary to specify the initial elastic modulus.

The thickness of the fiber at the time of displaying the initial elastic modulus should be shown in the state after swelling with water.
Since it is difficult to accurately obtain the value, the thickness of the fiber before swelling is used. The initial elastic modulus may be measured by a tensile tester, or, for example,
For a 1200 denier yarn, a load of about several g may be hung and the length may be calculated.

This cross-linked PVA fiber is recognized not only for improved hot water resistance but also for improved mechanical properties such as abrasion resistance, and in a hose such as an oil brake hose to which pulsation and vibration are applied during use, It is particularly useful because it has improved durability. However, for the purpose of reinforcement, the tensile strength of the PVA fiber must be 12 g / d or more. Further, in the radiator hose and the heater hose, the tensile strength residual ratio after the hot water treatment at 150 ° C. as defined above is 80 so that the PVA fiber does not melt even if the PVA fiber is in a swollen state due to a pinhole or the like. % Or more is required. Further, the initial elastic modulus after the hot water treatment at 180 ° C. is an index showing the degree of intermolecular crosslinking relating to hot water resistance and fatigue resistance, and this value is 1 × 10 ⁻³ g / d or more. By introducing the molecular crosslinks as described above, not only the hot water resistance is improved as described above, but also the mechanical properties such as wear resistance and fatigue resistance are improved, and the durability of the hose is improved.

[0018]

The rubber hose is heated under pressure to prevent foaming during rubber vulcanization.
A direct vulcanization method in which steam at a temperature close to ℃ is blown directly is adopted. At this time, if there is a pinhole in the hose, the PVA fiber in that portion is subject to wet heat deterioration. To discover this, all hoses are pressure tested. The hose of the present invention uses PVA fiber having high heat resistance and high vibration resistance, which can save the labor of the above-mentioned inspection and lead to great rationalization of the process. In addition, radiator hoses are molded into various shapes among automobile hoses. When the hose is vulcanized with a short length, steam enters from the end surface of the hose, and if the hot water resistance of the reinforcing thread is poor, both ends of the hose must be discarded, resulting in material loss. It is possible to significantly reduce the loss.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 PVA having a viscosity average degree of polymerization of 4100 and a saponification degree of 99.8 mol% was added to DMSO so as to have a concentration of 9.5% by weight, and dissolved at 70 ° C. in a nitrogen atmosphere. The obtained spinning dope was prepared with a hole diameter of 0.12 mm and a hole number of 30.
Nozzle from 0 to 3 ° C methanol / DMSO = 7/3
Wet spinning in a coagulation bath (first bath) consisting of (weight ratio),
The obtained coagulated yarn was further immersed in the same methanol / DMSO bath as the first bath (second bath). Then phosphoric acid 50ppm
DMSO was extracted by immersing it in a methanol bath (third bath) containing, and phosphoric acid was permeated into the yarn. The liquid content of Itosin after the second bath was 290%. Then phosphoric acid 5
Wet stretching was performed by immersing in a 40 ° C. methanol bath (4th bath) containing 0 ppm to make the total wet stretching ratio 5 times, and further DMSO was extracted through a methanol bath (5th bath) containing 50 ppm phosphoric acid. It was dried with hot air at 100 ° C.
In this way, a raw yarn after drying with phosphoric acid adhering to 120 ppm / PVA was obtained. Next, the first furnace 200 ℃, the second furnace 236
When stretched in a hot air oven having a temperature gradient of ° C, a total stretch ratio of up to 21 was possible. The total residence time in the furnace at the time of 21-fold stretching was 79 seconds.

The 21-times drawn yarn was colored black purple, and it was presumed that a dehydration crosslinking reaction had occurred. The yarn denier was 1200 d and its strength was 18.7 g / d.
Further, this yarn was immersed in hot water at 150 ° C. in an autoclave for a fixed length of 1 hour, taken out, dried, and then measured for strength retention, which was 92%, which was almost unchanged, indicating excellent hot water resistance. This yarn was left in hot water at 180 ° C. (in an autoclave) without tension for 60 minutes to form a rubber-like fiber, and its elastic modulus was measured and found to be 6.5 × 10 ⁻³ g / d.
This yarn is twisted 90 times / m, and resorcin-formalin latex (hereinafter RF
L) Treat with an adhesive liquid so that the solid content becomes 5%,
It was dried at a constant length of 110 ° C. and heat-treated at 160 ° C.
The physical properties of the yarn were hardly changed by this treatment.

The hose is manufactured in the same manner as conventional vinylon. That is, SBR rubber was extruded as an inner tube into a mandrel having an outer diameter of 3.2 mm, and PVA fibers were braided with 20 carriers as the first layer (inner layer) blade. The cord is braided from two 1200d yarns, wrapped with 0.2mm cushion rubber, and then 1200d
Braid with 24 carriers using the cord made of main yarn. Then, it is extrusion-coated as an EPDM type cover rubber. The outer diameter of the hose is 10.5 mm. Vulcanize for 60 minutes under steam steam at 150 ° C. Cut the resulting hose to 300 mm and attach metal fittings to both ends. When the metal fitting is attached, the cutting elongation of the reinforcing thread is low, so it is necessary to adjust the degree for caulking.

The performance of the brake hose manufactured in this way is as follows. That is, the burst pressure resistance is 1650K
g / cm ² . The hose expansion amount under a pressure of 100 kg / cm ² is 0.09 cc / ft. 60 in the whip test
2 when using uncrosslinked yarn for 0 hours or more
It is more than twice as good as 50 hours.

Example 2: Polymerization degree 3500, saponification degree 9
8% PVA was dissolved in water at a concentration of 12%, and boric acid was added thereto in an amount of 2% by weight based on PVA. After defoaming the solution, 5 mol% of nonylphenol ethylene oxide adduct (nonion HLB value = 16) was added to PVA in an amount of 5% by weight to prepare a spinning stock solution. The spinning stock solution heated to 130 ° C. was immediately wet spun from a nozzle into a 70 ° C. aqueous coagulation bath containing 20 g / l of sodium hydroxide and 320 g / l of Glauber's salt and allowed to stand at a speed of 6 m / min. 15g
It was soaked in a phosphorus ammonium bath of 1 / l, and 2% by weight phosphorus ammonium was attached to PVA to dry it. Then, roller stretching, neutralization, wet heat stretching, washing with water, and drying were carried out according to a conventional method. Continued 240
Dry heat drawing was carried out at 0 ° C. and wound on a bobbin. However,
The stretch ratio for collecting the beverage was 0.8 times the stretch ratio for breaking. Further, a constant length heat treatment was carried out at 230 ° C. for 30 seconds to obtain a crosslinked yarn.

The PVA synthetic fiber thus obtained had a single yarn denier of 2 d and a strength of 15 g / d, and the tenacity retention rate after hot water treatment at 150 ° C. was 85%. 180 as in Example 1
The initial elastic modulus of the fiber after ℃ hot water treatment is 9.5 × 10 ⁻³ g /
It was d.

To give this yarn (1800d) adhesion to rubber, R. F. Treated with L adhesive liquid, 3rd
I made a medium-reinforced automobile water hose belonging to the species. The inner diameter of the hose is 30 mm, and the breaking pressure is 15 kg / c.
create a radiator hose m ^2, JIS-D-260
At 120 ℃ same as the heat aging test of No.2, and also make a pinhole in the rubber, accelerate deterioration in hot water for 70 hours,
When the breakdown voltage is measured after standing for more than 14 hours, it is 14 Kg / c.
There was almost no decrease with m ² .

Claims (1)

Claims: 1. A hose using a polyvinyl alcohol fiber as a reinforcing material, which satisfies the following conditions (a), (b) and (c). (A) The tensile strength of the fiber is 12 g / d or more. (B) The tensile strength residual rate after standing for 60 minutes in hot water at 150 ° C. for a fixed length is 80% or more. (C) The initial elastic modulus after standing for 60 minutes in hot water at 180 ° C. without tension is 1 × 10 ⁻³ g / d or more.