JPS63239046A - Methanol-resistant rubber hose - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a methanol-resistant rubber hose for reinforcement with improved fiber deterioration resistance and metal deterioration resistance.

(Prior art and its problems) Chlorinated polyethylene, especially chlorinated polyethylene produced by a process that includes a chlorination process near the melting point of polyethylene solids, is a useful substance as a rubber material and is sufficiently crosslinked. As a result, it is known that it can exhibit superior mechanical properties, heat resistance, oil resistance, chemical resistance, and IK resistance among various synthetic rubbers. In recent years, chlorinated polyethylene has been developed for applications such as automobile fuel supply hoses, fuel tanks, and methanol storage tank linings because it has superior methanol resistance compared to other rubber materials. It has been proposed by two of the applicants that it is effective to use a specific chlorinated polyethylene for this purpose (Japanese Patent Application No. 60-220768@)
.

When rubber materials are used as a fuel hose, not only for methanol fuel but also for gasoline fuel, the physical properties that are particularly important are the inner layer's resistance to swelling and extraction of the fuel used, as well as the joints.

These include metal deterioration resistance in the contact area with the mouthpiece, and weather resistance, ozone resistance, abrasion resistance, lubricating oil resistance, etc. in the outer layer.

In addition, in recent years, the physical properties required for hoses have become more stringent, and the range of applications has expanded, so hose shapes have become more complex.
The number of laminated structures made of different rubber materials has increased from single-layer structures, and from the viewpoint of strength and shape retention, fibrous reinforcing layers in which reinforcing threads are woven between the rubber layers are often used. Therefore, one of the important physical properties required is that the rubber material does not deteriorate the reinforcing thread.

In general, many polymers undergo deterioration to varying degrees when used in contact with metals. .

If it comes into contact with copper, etc., or their alloys, or even these compounds at high temperatures, or comes into contact with them for a long time in high-temperature liquids containing them, dehydrochlorination may occur, causing significant deterioration of the polymer itself. Are known.

The hydrochloric acid released from roughly chlorinated polyethylene deteriorates the reinforcing yarn woven between the hose layers, reducing the pressure resistance of the hose.
The problem is that the strength etc. decrease.

Reinforcing threads are generally polyvinyl alcohol fibers.

Polyamide fibers, polyester fibers, etc. are used, among which polyvinyl alcohol fibers.

Polyamide fibers are easily hydrolyzed in an acidic atmosphere and are therefore subject to significant deterioration. In particular, polyvinyl alcohol-based fibers are currently widely used as reinforcing yarns for fuel liquid-feeding hoses, and it is currently difficult to change to other yarns due to their physical properties.

(Means for Solving the Problems) In view of the above points, the present inventors have conducted repeated research and found that a cross-linked composition of chlorinated polyethylene to which specific hydrotalcites have been added has been developed for use in caps, reinforcing threads, etc. By using it in parts that come into contact with other materials, we succeeded in obtaining a methanol-resistant rubber hose with improved resistance to both metal deterioration and reinforcing yarn deterioration.

That is, in the present invention, multiple layers made of crosslinked rubber are formed through a fibrous reinforcing layer, and at least the crosslinked rubber in the inner layer contains 5 to 50 parts by weight of hydrotalcite and a crosslinking agent based on 100 parts by weight of chlorinated polyethylene. A methanol-resistant rubber hose characterized by being a crosslinked product of a rubber composition containing:

The methanol-resistant rubber hose of the present invention refers to a fuel hose for a methanol engine, a rubber hose used when transferring methanol to a tank, etc.

Also, methanol resistance refers not only to methanol, but also to ethanol, propyl alcohol, isopropyl alcohol,
This includes resistance to monohydric lower aliphatic alcohols such as n-butyl alcohol and tert-butyl alcohol. In addition, in practice, not only pure methanol but also methanol with gasoline added may be used as a fuel, so the same resistance is required for methanol mixed with gasoline in an amount of up to 20% by volume. required to have one. Practical test conditions and specifications include that when a rubber product is immersed in methanol or gasoline-added methanol at 40°C for 48 hours, the degree of volumetric swelling must be 20% by volume or less, preferably 10% by volume or less. be. If the volumetric swelling is higher than this value, metals, sulfur, etc. in the rubber will be easily extracted. The evaluation method is shown in JIS K6301, and comparisons are made by measuring the tensile strength, elongation reduction rate, etc. after alcohol immersion.

The chlorinated polyethylene used as the inner layer component of the hose of the present invention is chlorinated polyethylene having an arbitrary chlorine content and crystallinity 1 molecular weight distribution, but the average molecular weight is
It is preferable to chlorinate polyethylene with a molecular weight of 000 or higher at a temperature close to its melting point by an aqueous suspension method. If the average molecular weight of the raw material polyethylene is less than 50,000, the strength will be insufficient when used as a rubber hose. Generally, a larger average molecular weight is preferable, but if it is too large, moldability will deteriorate, especially due to high viscosity. Since deterioration in extrusion processability etc. occurs, it is appropriate to use a raw material polyethylene having a small average molecular weight of less than 300,000.

The chlorinated polyethylene used in the present invention is a substantially amorphous rubber, and powdered polyethylene, preferably high-density polyethylene with a particle size of 20 to 300 mesh, is processed by a low-pressure method into an aqueous suspension at 100 to 140°C. Contains chlorine under pressure of 50 to 50 ω%, preferably 25 to 45 ω%
% by chlorination.

The hydrotalcites used in the present invention are hydrous double salt compounds consisting of magnesium and aluminum represented by the following general formula (I).

MCh-xAfJ x (OH)2 AX/2
・mH20(I) (in the above formula, X is 0<X≦0,
is a real number in the range of 5, A indicates C03 or S03,
m indicates a real number. ) The amount of the hydrotalcites used is 5 to 50,000 parts by weight, preferably 7 to 40 parts by weight, and more preferably 15 to 40 parts by weight, per 100 parts by weight of chlorinated polyethylene. If the amount is less than 5 parts by weight, the improvement in metal deterioration resistance and reinforcing yarn deterioration resistance will not be sufficient, and if it is more than 50 parts by weight, the above properties will not be improved so much.
This results in an unfavorable result in that workability deteriorates.

In the present invention, hydrotalcites are presumed to act as stabilizers for metal materials and reinforcing threads, so it is conceivable to directly treat the metal surface or reinforcing threads with hydrotalcites. Since it is a powder, it is difficult to handle and uniform treatment is not easy.

The method of adding hydrotalcites during kneading of a rubber composition is simple and industrially useful.

It is already known that hydrotalcites are used as acid acceptors for crosslinking chlorinated polyethylene, and there is no practical problem even if they are not used together with other acid acceptors, but other acid acceptors,
By using it in combination with a stabilizer, it has excellent metal deterioration resistance,
Yarn deterioration resistance may be improved in some cases. In this case, the total amount of hydrotalcites and other acid acceptors is preferably 20 to 401 parts by weight per 100 parts by weight of chlorinated poly-1-dylene. Such acid acceptors and stabilizers include magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, calcium silicate, calcium carbonate, magnesium stearate, and barium stearate.

Cadmium oxide, cadmium stearate, tin stearate, sibdeltin malate, -lead oxide, red lead, white lead, dibasic lead phosphite, dibasic lead sulfate, and the like. Further, metal deterioration inhibitors such as 3-amino-1,2,4-triazol derivatives and polymethylenedicarboxylic acid-di-hydrazine derivatives can also be added.

Crosslinking of the rubber composition can use thiourea derivatives, thiuram sulfides, and trithiol triazine compounds. Furthermore, in order to fully exhibit the effects of the present invention, it is preferable to use an organic peroxide. Examples of such organic peroxides include dicumyl peroxide, di-t-butyl peroxide, 1,3-bis(t-butylperoxyimprovil)benzene, and 4,4-di-t-butylperoxyvalerin. Acid-n-butyl ester, 1.
1-di-t-butylperoxy-3,3,5-trimethylcyclobequinone, α,α'-bis(t-butylperoxy>-p-diisopropylbenzene, 2,5-dimethyl-2,5 -di(t-butylperoxy)hexyne-3 and the like, and are used in an amount of 1 to 15 parts per 100 parts of chlorinated polyethylene.

For the purpose of promoting processability and crosslinking, reactive mixtures such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, etc. are added to chlorinated polyethylene 100.
It can be added in an amount of 20 iffi parts or less based on the weight part.

Other compounding agents include various fillers, reinforcing agents, plasticizers, processing aids, etc. that are commonly used in this technical field.
Anti-aging agents, pigments, flame retardants, blowing agents, etc. can be optionally blended.

It is also possible to use a blend of acrylonitrile-butadiene rubber, styrene-butadiene rubber, ethylene-propylene rubber, etc. with chlorinated polyethylene as the rubber material.

In order to 'AN' the hose of the present invention, any means conventionally used in the rubber processing field, such as mixing rolls, Banbury mixers, and various kneaders, are used to compound the mixture, and then an inner layer is formed using an extruder and then reinforced. The yarns are knitted together to form a fiber layer, then an outer layer is covered with an extruder and molded, and in the case of multi-layered products, this process is repeatedly molded. Thereafter, thermal crosslinking is performed using steam color, air pass, microwave, etc. Crosslinking is usually carried out by heating at 120-200'C for 0.5-60 minutes.

In the hose of the present invention, the liquid contacting part of the inner layer may be made of a chlorinated polyethylene crosslinked composition containing the above-mentioned hydrotalcites, and the outer layer may be made of any rubber. However, since the chlorinated polyethylene crosslinked composition containing hydrotalcites has excellent weather resistance, impact resistance and other physical properties, it can be used as is as an outer layer.

Even for hoses with three or more layers, it is possible to obtain a hose having the effects of the present invention, and for this purpose, it is possible to obtain a hose that has the effects of the present invention by using a chlorinated layer containing the above-mentioned hydrotalcites in the layer that is in direct contact with the cap and the reinforcing thread. It is necessary to use polyethylene crosslinked compositions.

Examples and comparative examples are shown below, and the percentages of components in the examples are shown below.

All parts are based on mold can standards.

Examples 1-9. Comparative Examples 1 to 5 Heavy weight average molecular weight 150.000. A low-pressure polyethylene powder with a density of 0.947 was prepared under pressure in an aqueous suspension.
Chlorinated polyethylene rubber chlorinated at 5 to 130°C to a chlorine content of 30 to 43% was used in each Example and Comparative Example.

Each composition shown in Table 1 was kneaded for 15 minutes with a mixing roll at 60'C, formed into a sheet, and placed in a mold for 160 minutes.
℃, 100K! Each crosslinked product was obtained by heating with II/CIrt for 30 minutes. The results are shown in Table 2.

In addition, each of the above sheets has a L/D = 15. Extrusion was carried out using an extruder with a diameter of 20 mm under the conditions of a screw part set temperature of 70'C, an extrusion part set temperature of 0°C, and a screw rotation speed of 3 Orpm to obtain an inner layer rubber hose with an outer diameter of 11 mm and an inner diameter of 7 mm. After providing the surface of the rubber hose formed in this way with a fiber layer made by knitting reinforcing threads made of polyvinyl alcohol fibers into a net shape, an outer layer having the same composition as the inner layer and a thickness of 1.5 mm was placed on the surface. Finally, it was molded into a rubber hose having a reinforcing fiber layer with an outer diameter of 14 mm and an inner diameter of 7 mm. After cross-linking this hose in a steam can at 160°C for 20 minutes, it was cut to a length of 60 mm and an outer diameter of 1
Insert about 30mm into a 0mm test metal tube 135
After being left in a gear oven at a temperature of 360 hours, the contamination state on the surface of the metal tube and the presence or absence of cracks on the metal contact surface of the rubber tube were examined. The metal tubes used for the test were made of a GLI tube with nickel plating and a steel tube with zinc chrome plating. The criteria for evaluating the contamination state of the metal pipe surface are as follows.

◎ No change.

O The surface is slightly discolored.

△ Slightly corroded.

× It is quite corroded.

The cracks on the rubber surface are as follows.

Q: No crack.

× There is a crack.

We also investigated the state of deterioration of the reinforcing threads in the parts that were in contact with the metal parts. The initial color of the thread was white, and the evaluation criteria were as follows.

○ No change.

Δ　The thread is slightly discolored to brown.

・× The color has changed considerably to brown, and the reinforcing thread has shrunk.

From Tables 1 and 2, it is clearly observed that Comparative Examples 3 to 5, which do not contain hydrotalcites, have lower metal deterioration resistance and reinforcing yarn deterioration resistance compared to Examples.

Furthermore, Examples 4, 5, and 6, in which magnesium oxide, hydroxide, and calcium hydroxide were used in combination, had significantly better metal deterioration resistance than the case in which they were not used. Comparative Examples 1 and 2, which contain a small amount of hydrotalcites, have lower metal deterioration resistance than each Example, and the Comparative Examples generally have a large degree of volumetric swelling after immersion in methanol/fuel oil C. It's admittedly awkward.

(Effects of the Invention) The rubber hose of the present invention has a crosslinked material in the inner layer made by crosslinking chlorinated polyethylene with hydrotalcites, so it has excellent not only methanol resistance but also metal deterioration resistance and fiber deterioration resistance. , corrosion of metal parts such as the joint 9 cap and damage to the fiber reinforcing layer is less likely to occur, and the life of the hose can be extended.

Furthermore, since it has excellent properties such as weather resistance and impact resistance necessary for a rubber hose, it can be used not only as an inner layer but also as an outer layer of a rubber hose.

Claims (2)

[Claims] (1) Multiple layers made of crosslinked rubber are formed through a fibrous reinforcing layer, and at least the crosslinked rubber in the inner layer is a rubber containing 5 to 50 parts by weight of hydrotalcite and a crosslinking agent based on 100 parts by weight of chlorinated polyethylene. A methanol-resistant rubber hose characterized by being a crosslinked product of the composition. (2) Claim 1, wherein the fibrous reinforcing layer is a woven layer of polyvinyl alcohol fibers or polyamide fibers.
Rubber hose.