JPH04171378A - Rubber hose - Google Patents

Abstract

PURPOSE:To facilitate handling of vulcanizating agents, improve productivity, and the performance of a rubber hose by specifying the iodine value of EPDM, using the active zinc oxide as the zinc oxide compounded in the rubber vulcanizate, and setting the compounding quantity of the zinc oxide to a prescribed value, and using the sulfur vulcanization system as the vulcanization system for the rubber vulcanizate. CONSTITUTION:As for a brake hose, the whole is constituted of a five-layer constitution of an inner tube rubber layer 1, first reinforced thread layer 3, intermediate rubber layer 5, second reinforced thread layer 7, and an outer tube rubber layer 9. The inner tube rubber layer 1 is formed from a specific EPDM vulcanizate, and the first and second reinforced thread layers 3 and 7 are formed from polyvinyl alcohol fiber treads which are treated with resorcin-formalin latex, and the intermediate rubber layer 5 is formed from the natural rubber or butyl rubber vulcanizate, and further an outer tube rubber layer 9 is formed from the vulcanizate of the versatile-used EPDM. The iodine value of the EPDM in a specific EPDM vulcanizate is 20-35, and the zinc oxide compounded in the rubber vulcanizate is the active zinc oxide, and the compounding quantity of the zinc oxide is 1-10PHR, and the vulcanization system for the rubber vulcanizate is the sulfur vulcanization system.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a rubber hose, in which the contacting fluid is non-mineral oil-based, and is suitable for use in high-pressure reinforced hoses such as brake hoses (see Figure 1) having a caulked joint. It is suitable. Here, explanation will be given mainly using a brake hose as an example, but the invention is not limited to this.

In addition, in the following explanation, the compounding unit "parts" is "parts by weight" unless otherwise specified, and r PH
RJ means the blending amount based on 100 parts of the polymer component.

<Prior Art> Conventionally, styrene-butadiene rubber (hereinafter abbreviated as SBR) has been the mainstream material for forming the inner tube rubber layer of a brake hose.

However, in order to meet the recent demands for improved heat resistance, S
Substituting BR with ethylene-a-olefin-diene copolymer (hereinafter referred to as rEPDMJ) is being considered.

However, when EPDM with a suitable formulation is applied to the inner pipe layer of a brake hose, under the above-mentioned strict conditions, there is no reliable connection between the inner pipe rubber layer 3 of the brake hose and the nipple lla of the hose joints 1 and 1. It was difficult to obtain sealing properties (especially resistance to settling) (Fig. 1).

<'Problems to be Solved by the Invention>';; ￥N Akashi et al. did not solve this problem of sealing property, but found that a specific E (0M peroxide-based vulcanizate r inner tube rubber 'P
MZ: I came up with this idea (Unexamined Japanese Patent Application Publication No. 1983-2/
1105] Publication No. 9).

L5 (11) Since the vulcanization system is peroxide-based, handling of the vulcanizing agent is troublesome.
It was necessary to perform the vulcanization inside the container, which resulted in poor productivity.

In order to prevent the above problems from occurring, the vulcanization system is
It is conceivable to use Iaffi yellow vulcanization system, but a person skilled in the art said that (,!), it is said that sulfur vulcanization system cannot obtain sufficient compression set property for EPDM vulcanizate. was.

In view of the above, the present invention has developed a vulcanization system that is sulfur-cured (11 and 17 systems) to achieve compression set resistance equivalent to that of the conventional 5r3R, while also achieving 1j heat resistance (including heat aging resistance).

), 5 and 5 to provide a rubber hose with excellent weather resistance.

and Means for Solving the Problems> As a result of intensive studies to achieve the above object, the present inventors have found that if active zinc white is used as the galvanizing compound in the vulcanizate, a certain level of resistance can be achieved. They discovered that compression set properties can be maintained and came up with the present invention having the following configuration.

In a rubber hose in which at least one layer is formed of a rubber vulcanizate containing EPDM as the entire or main rubber component, (1) the EPDM has an iodine value of 20 to 35, and (2) the zinc blended in the rubber vulcanizate. The white color is activated zinc white, the amount thereof is 1 to 10 PHR, and (2) the vulcanization system of the rubber vulcanizate is a sulfur vulcanization system.

<Detailed explanation of the configuration> The above configuration will be explained in detail below.

(1) The above EPDM is obtained by introducing ethylene, α-olefin and diene into an inert solvent in the presence of a suitable catalyst and polymerizing the mixture under normal pressure or slightly increased pressure. This polymer should have an iodine value of 20 to 35 (propylene-1 is usually used as the α-olefin mentioned above, but propylene-1, etc. may also be used. Dennorbornenebu [I benylnorbornene, vinylnorbornene, knock 11 pentadiene, 1,4-hexadiene, 2-methyl-1,5-hexadiene, 1,6-occudif, 1,5-octadiene, 1.7-octadiene,! , 4-octadiene, methylhydroindene, etc. may be used alone or in combination of two or more thereof, or C may be used in combination with a conjugated diene such as butadiene, isoprene, etc.

(pIf the above iodine value is less than 20, the required strength...
5 r)' Compression set resistance is difficult to obtain. On the other hand, those with an iodine value of 4 or 5 have many crosslinking points, the modino'7 becomes too high, and polymer production from 1 to
．． :j4 Police'i L, hard.

(',,+In the above E P D M, preferably,
Molecular weight)・Cloth? aw, /Pn≦50, and the a-1, 7-r composition distribution is 20 wt% on both sides of the molecular weight distribution. When the molecule side is C and E,
C-EC5I≦5. It is desirable to have sharpness defined by Owt%.By meeting these requirements,
In particular, improvements in galling resistance etc. can be expected.

Incidentally, the molecular weight distribution Mw /
Pn = 8-20, α-olefin composition distribution C3E-C3
I=8-15%.

■Other characteristics of the above EPDM are that the ethylene content is usually 60
Contains ~70% α-olefin! 30-40%, diene (third component) content 5% or less relative to the total of ethylene and α-olefin @i oo%, Mooney viscosity (ML 1.41
00°C) 35-55.

(3) The rubber component may be EPDM alone, but is preferably a mixture containing transpolyoctenylene rubber (hereinafter referred to as rTORJ).

(2) The above TOR is a metathesis polymer of cyclooctene mainly having trans double bonds. EPDM
The blending amount is 5 to 15 parts, preferably 7 to 12 parts, based on 100 parts of the polymer. In the range of less than 5 parts and in the range of more than 15 parts, the surface of the product becomes rough and the extrusion rate becomes smaller than that of SBR, and no improvement in extrusion processability can be expected.

(4) For the rubber component containing EPDM as a whole or as a main component, compounding agents commonly used in sulfur vulcanization systems of EPDM, carbon black, zinc white, processing aids, anti-aging agents, coloring agents, etc. may be added as appropriate. Blend and then add sulfur vulcanizing agent.

■Here, zinc white is used as active zinc white, and the blending amount is 1
~10 PHR (preferably 3-7 PHR). Here, the active zinc white refers to one having a particle size of around 0.1 μm, which is smaller than the particle size of general zinc white of 0.3 to 0.7 μm, and a significantly high activity.

Furthermore, if the amount of active zinc white is less than IPHR, the vulcanization will be slow, and if it exceeds 10 PHR, the strength of the rubber vulcanizate is likely to be adversely affected.

■Carbon black may be a regular carbon black, but the iodine adsorption amount 4
0~s Omg/g, dibutyl phthalate oil absorption 140
It is desirable to blend so-called high oil absorption type furnace carbon black with m1/g or more to further improve wear resistance, galling resistance, and setting resistance (
The blending amount is preferably 40 to 60 PHR).

(2) Specific examples of the processing aids include higher fatty acids, and examples of the anti-aging agents include poly(2,2,4-)limethyl-1°2-dihydroquinoline.

(5) The rubber compound thus obtained is extruded and vulcanized using a conventional extrusion molding machine to obtain the rubber hose of the present invention.

For example, in the case of a brake hose, it is desirable to have a configuration as shown in FIG.

The overall structure has a five-layer structure including an inner tube rubber layer 1, a first reinforcing yarn layer 3, an intermediate rubber layer 5, a second reinforcing yarn layer 7, and an outer tube rubber layer 9. The inner tube rubber N1 is made of a specific EPDM vulcanizate used in the present invention, and the first and second reinforcing yarn layers 3.7 are made of polyvinyl alcohol fiber yarn treated with resorcinol formalin latex (RFL). The intermediate rubber layer 5 is formed of a vulcanized product of natural rubber (CNR) or butyl rubber (FIR), and the outer tube rubber layer 9 is formed of a vulcanized product of general-purpose EPDM. The intermediate rubber layer 5 is formed mainly to prevent interference between the reinforcing yarn layers 7.9, and has a wall thickness of 0.1 to 0.3.
It is a thin layer of mm.

In addition, in the case where the brake hose does not have an intermediate rubber layer and the reinforcing thread layer is a single-layer type, if the inner tube rubber layer of the brake hose is formed with the above rubber compound, - the boat fishing is provided with an outer tube rubber layer made of EPDM. For brake hoses, only one type of adhesive is needed for the reinforcing thread layer and the inner and outer tube rubber layers. On the other hand, in the past, since the inner tube rubber layer was made of SBR, different types of adhesives were required for the inner tube rubber layer and the reinforcing yarn layer, and for the reinforcing yarn layer and the outer tube rubber layer, respectively.

<Operations and Effects of the Invention> As described above, the rubber hose of the present invention has at least one layer formed of a rubber vulcanizate containing EPDM as the entire or main rubber component;
DM has an iodine value of 20 to 35, and (1) the zinc white mixed in the rubber vulcanizate is activated zinc white, and the amount thereof is 1
~10 PHR"C, (2) The vulcanization system of the rubber vulcanizate is a sulfur vulcanization system, so the following actions and effects are achieved.

The rubber hose of the present invention may be sulfur-cured as the vulcanized system.
It has compression set resistance equivalent to that of conventional SBR, and is also excellent in heat resistance (including KL heat aging resistance) and moisture permeation resistance.

Therefore, unlike conventional vulcanization systems, a peroxide-based vulcanization system is not used; in other words, since it is a sulfur-based vulcanization agent, handling of the vulcanization agent is easy, and vulcanization does not need to be performed in an inert gas atmosphere. In addition, by using a sulfur vulcanization system, it is expected that the physical properties and oil resistance of the rubber vulcanizate will be improved compared to peroxide vulcanization systems. As a result, the performance of the rubber hose is improved.

<Example> Hereinafter, the present invention will be further described in detail based on Examples.

EPDM having the characteristics shown below was used.

Note that propylene was used as the α-olefin component, and ethylidene norbornene was used as the diene component. At this time F7w/? Wn was determined from the molecular weight distribution measured by gel permeation chromatography (solvent: 0-dichlorobenzene). Further, Cs) MeC and I were determined from the molecular weight distribution measured by a fractional precipitation method (number of fractions: 10 or more, solvent dichlorohexane/isopropyl alcohol).

Ethylene content: 64% Iodine value: 29 Viscosity (ML+ +4100°C): 47 Mw/Mn3. I C, E-C, I 3 In the Examples and Comparative Examples, rubber materials having the following EPDM formulation were used. In the Examples, the zinc white was activated zinc white, and in the Comparative Examples, normal inactive zinc white was used. In the reference example, a rubber material having the following SBR formulation was used.

"Dan" and U's γ history J EPDM 90th part T OR*
1.0 parts Furnace black (H3) 50 parts Active zinc white or inactive zinc white 5 parts Processing aid (
Higher fatty acid type) 3-part anti-aging agent
1.5 parts powdered sulfur
0.6 part vulcanization accelerator 4
．． 75 parts* Vestenamer 8012 (Hüls: trade name) 11 and N Douhou SBR 100 parts Furnace black 60 parts Inactive zinc white 5 parts Stearic acid
1 part anti-aging agent
4 parts sulfur 05 parts vulcanization accelerator 3 parts The above-mentioned furnace black used was the following high oil absorption type in Examples and Comparative Examples, and the normal type was used in Reference Examples.

High oil absorption Normal iodine adsorption amount (mg/g) 58 53 Dibutyl phthalate oil absorption ffi (ml/100g) 190 133E
A compounded rubber material is prepared by kneading each rubber compound according to the prescribed recipe, and a test piece for a compression set test is prepared from the rubber material based on JIS k 6301, and a compression set test (12
0°C x 22h).

The test results were: Example: 36%, Comparative Example: 50%, Reference Example: 35%. From this result, the EPDM vulcanizate using activated zinc white is different from the EPDM vulcanizate using inactive zinc white.
It can be seen that it shows better compression set resistance than the DM vulcanizate, and its value is equivalent to that of the SBR vulcanizate.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the brake hose at the joint. DESCRIPTION OF SYMBOLS 1... Inner tube rubber layer, 3... 1st reinforcing thread layer, 5... Intermediate rubber layer, 7... Second reinforcing thread layer, 9... Outer tube rubber layer, 11... Fittings. Patent application Toyoda Gosei Co., Ltd.

Claims (1)

[Claims] Ethylene-α-olefin-diene copolymer (hereinafter referred to as EP
Abbreviated as DM. ) in a rubber hose in which at least one layer is formed of a rubber vulcanizate containing all or a main component of the rubber component, (1) the EPDM has an iodine value of 20 to 35, and (2) the rubber vulcanizate. (3) A rubber hose characterized in that the blended zinc white is activated zinc white, and the blended amount thereof is 1 to 10 PHR, and (3) the vulcanization system of the rubber vulcanizate is a sulfur vulcanization system.