JP6073730B2 - Heat resistant hose - Google Patents

Description

  The present invention relates to a heat resistant hose, and more particularly to a heat resistant hose used as an air hose such as a turbo air hose in a transport machine such as an automobile.

  Conventionally, acrylic rubber having excellent heat resistance has been mainly used as a material for forming heat-resistant hoses such as automobile turbo air hoses (see Patent Document 1).

  The hose as described above is usually attached to each device in the engine room by inserting a substantially cylindrical hose base provided in each device into the end opening of the hose. Therefore, in addition to heat resistance, the hose is also required to have improved resistance to disconnection from the hose base.

  In addition to heat resistance, the hose is also required to have improved low temperature properties (flexibility at low temperatures).

JP 2012-207748 A

  However, when the hose innermost layer is made of an acrylic rubber composition, the interaction between the inner peripheral surface of the hose and the metal (hose base) is small due to its high polymer crystallinity. When the pressure is applied, the plasticizer in the innermost layer tends to ooze out to the inner peripheral surface of the hose, so that the slip resistance value of the inner peripheral surface of the hose becomes small. As a result, there arises a problem that the hose can be easily detached from the hose base.

  Further, when the acrylic rubber composition is used for the hose material as described above, the plasticizer as described above oozes out because the low temperature property cannot be improved unless a plasticizer is blended in the rubber composition. There is a demand for improving the low-temperature properties of the hose while suppressing this.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a heat-resistant hose that is excellent in resistance to disconnection from a hose base while maintaining low temperature properties.

In order to achieve the above object, the heat-resistant hose of the present invention is a heat-resistant hose provided with at least one constituent layer, the innermost layer of which is the following (A) as a main component and the following (B) as a plasticizer component The acrylic rubber composition is used.
(A) An acrylic polymer obtained by copolymerizing an acrylic ester component and a crosslinkable monomer , wherein the acrylic ester component is composed of ethyl acrylate (EA) and butyl acrylate (BA), and its weight ratio Is an acrylic polymer in which EA: BA = 4: 6 to 8: 2.
(B) A plasticizer comprising an ether / ester plasticizer and an ester plasticizer, the weight ratio of which is ether / ester plasticizer: ester plasticizer = 3: 7 to 7: 3.

That is, the present inventors have intensively studied to solve the above problems. In the course of the research, the present inventors used an acrylic rubber excellent in heat resistance and the like for the rubber composition for forming the innermost layer of the hose, and an ester plasticizer excellent in the low temperature property improving effect. I recalled blending. However, when an ester plasticizer is used alone as a plasticizer, there is a problem that the plasticizer oozes out on the inner peripheral surface of the hose due to the fitting with the hose base. Thus, when an ether / ester plasticizer is used in combination with the ester plasticizer at a specific ratio, it has been found that the bleeding of the plasticizer is suppressed. On the other hand, as a polymer of the acrylic rubber, when using the acrylic polymer by copolymerizing a and crosslinkable monomer and acrylic acid ester component, an acrylic acid ester component of that is, if it is ethyl acrylate (EA) alone, While excellent in heat resistance, the polymer crystallinity becomes high, and the problem of bleeding of the plasticizer may occur again. Therefore, when butyl acrylate (BA) that suppresses high crystallization of the polymer and has high affinity with the above-mentioned specific plasticizer (particularly compatibility with the ether / ester plasticizer) is used in combination with EA at a specific ratio, The present inventors have found that the intended purpose can be achieved, and have reached the present invention.

  As described above, in the heat resistant hose of the present invention, the innermost layer is made of an acrylic rubber composition containing a specific acrylic polymer as a main component and a specific plasticizer. Therefore, it is excellent in heat resistance and also excellent in resistance to pulling out from the hose base while maintaining low temperature. Therefore, it is suitable as a hose used in a place such as an engine room where heat and vibration are generated, such as a turbo air hose for automobiles.

  Next, embodiments of the present invention will be described in detail.

The heat-resistant hose of the present invention is not particularly limited even if it has a single layer structure or a multilayer structure in which two or more layers are laminated, but at least the innermost layer (in the case of a single layer structure, The layer) is made of an acrylic rubber composition having the following (A) as a main component and the following (B) as a plasticizer component. Here, the “main component” of the acrylic rubber composition is a substance (acrylic polymer) that greatly affects the properties of the entire composition. In the present invention, 50% by weight or more of the entire composition is used. means.
(A) An acrylic polymer obtained by copolymerizing an acrylic ester component and a crosslinkable monomer , wherein the acrylic ester component is composed of ethyl acrylate (EA) and butyl acrylate (BA), and its weight ratio Is an acrylic polymer in which EA: BA = 4: 6 to 8: 2.
(B) A plasticizer comprising an ether / ester plasticizer and an ester plasticizer, the weight ratio of which is ether / ester plasticizer: ester plasticizer = 3: 7 to 7: 3.

  As the specific acrylic polymer (A), an acrylic acid ester component composed of ethyl acrylate (EA) and butyl acrylate (BA) is used. Examples of the butyl acrylate (BA) include n-butyl acrylate, iso-butyl acrylate, and tert-butyl acrylate.

  And as above-mentioned, the weight ratio of EA and BA in acrylic polymer (A) needs to be 4: 6-8: 2, Preferably it is the range of 6: 4-7: 3. That is, if the ratio of EA is too small, the heat resistance is inferior, and if the ratio of EA is too large, the compatibility with the plasticizer decreases.

  The specific acrylic polymer (A) has the above monomer composition and is copolymerized with a crosslinkable monomer by a known method such as emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization and the like. The type and molar ratio of the crosslinkable monomer are not limited. For example, 2-chloroethyl vinyl ether, active chloro-based vinyl chloroacetate, butenedionic acid monoalkyl ester, specifically maleic acid monoalkyl ester, fumaric acid monoalkyl ester, Examples include carboxyl monomers such as itaconic acid monoalkyl ester, and epoxy monomers such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and methallyl glycidyl ether, which are copolymerized at a ratio of 0.5 to 2% by weight. be able to.

  As the plasticizer (B) used together with the specific acrylic polymer (A), an ether / ester plasticizer and an ester plasticizer are used in combination. The weight ratio needs to be ether / ester plasticizer: ester plasticizer = 3: 7 to 7: 3, preferably in the range of 4: 6 to 6: 4. That is, if the proportion of the ether / ester plasticizer is too small, the inner surface of the hose is pressurized, and the plasticizer of the ester plasticizer tends to ooze out. If the proportion of the ester plasticizer is too small, This is because the improvement effect cannot be obtained.

  The content ratio of the specific plasticizer (B) in the acrylic rubber composition is in the range of 5 to 50 parts with respect to 100 parts by weight (hereinafter abbreviated as “part”) of the specific acrylic polymer (A). It is preferable that it is in the range of 5 to 10 parts. That is, if the content of the plasticizer is too large, the hose inner surface is pressurized and the plasticizer oozes out easily. If the content of the plasticizer is too small, the low temperature property is inferior. It is.

  In addition to the specific acrylic polymer (A) and the specific plasticizer (B), the acrylic rubber composition includes a vulcanizing agent, a vulcanizing aid, a processing aid, a process oil, and carbon black. A white filler, an anti-aging agent, a flame retardant and the like are appropriately blended as necessary.

  Examples of the vulcanizing agent include imidazole compounds such as 1-methylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, hexamethylenediamine, and hexamethylene. Diamine carbamate, tetramethylenepentamine, hexamethylenediamine-cinnamaldehyde adduct, ammonium benzoate, hexamethylenediamine dibenzoate salt, 4,4′-methylenedianiline, 4,4′-oxyphenyldiphenylamine, m-phenylenediamine, p-phenylenediamine, 4,4'-methylenebis (o-chloroaniline), etc. are used.

  Examples of the vulcanization aid include trimethylthiourea, stearyltrimethylammonium bromide, di-o-tolylguanidine and the like.

  Examples of the processing aid include stearic acid, n-octadecylamine, polyoxyethylene stearyl ether phosphoric acid and the like. These may be used alone or in combination of two or more.

  Examples of the process oil include naphthenic oil, paraffinic oil, and aroma oil.

  Examples of the anti-aging agent include 4,4 ′-(α, α-dimethylbenzyl) diphenylamine.

  The heat-resistant hose of the present invention can be manufactured, for example, as follows. That is, the specific acrylic polymer (A), the specific plasticizer (B), the vulcanizing agent, the vulcanizing auxiliary, the processing auxiliary, the process oil, the carbon black, the white filler, the anti-aging agent, the difficulty An acrylic rubber composition is prepared by appropriately mixing a flame retardant and kneading using a kneader such as a roll, a kneader, or a Banbury mixer. Next, the acrylic rubber composition is extruded into a tubular shape (cylindrical shape) to form an unvulcanized rubber layer. When the heat-resistant hose of the present invention has a multilayer structure, layers made of various rubbers and resins are formed on the outer periphery of the rubber layer (innermost layer) by extrusion molding or the like. When the reinforcing yarn layer is formed, the reinforcing yarn layer is formed by braiding the reinforcing yarn with a predetermined number of draws and driving numbers on the outer periphery of the rubber layer (innermost layer). The mandrel is inserted into the unvulcanized hose structure thus obtained, vulcanized with steam under a predetermined condition (for example, 160 ° C. × 60 minutes), then the mandrel is extracted, The target hose can be produced by performing secondary vulcanization in an oven under the above conditions (for example, at 150 ° C. for 8 hours).

  In the heat-resistant hose of the present invention, the thickness of the rubber layer (innermost layer) is preferably 0.25 to 20 mm, particularly preferably 0.5 to 10 mm. The inner diameter of the hose is preferably 2 to 100 mm, particularly preferably 5 to 70 mm.

  The heat-resistant hose of the present invention can be used for all hoses requiring heat resistance, but is suitably used as an air hose for automobiles through which high-temperature air flows, such as a turbo air hose (supercharger air hose).

  Next, examples will be described together with comparative examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.

  First, prior to the examples and comparative examples, the following materials were prepared.

[Acrylic polymer]
An acrylic polymer obtained by copolymerizing an acrylate ester and glycidyl acrylate (ACM, glycidyl acrylate is 1% by weight), the acrylate ester component consisting of ethyl acrylate and n-butyl acrylate, Acrylic polymers (i) to ( v ) whose weight ratios are shown in Table 1 below

〔stearic acid〕
LUNAC S-30, manufactured by Kao

[Anti-aging agent]
4,4′-bis (α, α-dimethylbenzyl) diphenylamine (Naugard 445, manufactured by Chemtura)

〔Carbon black〕
Seast 116HM, manufactured by Tokai Carbon

[Plasticizer (i)]
Ether / ester plasticizer (ADEKA RS-107, manufactured by ADEKA)

[Plasticizer (ii)]
Ester plasticizer (ADEKA P-200, manufactured by ADEKA)

[Liquid paraffin]
Liquid paraffin 70S, manufactured by Sanko Chemical Co., Ltd.

[Imidazole compound]
1, 2-dimethylimidazole (SN-25, manufactured by Shikoku Chemicals Corporation)

[Thiourea compound]
Trimethylthiourea (Noxeller TMU, manufactured by Ouchi Shinsei Chemical)

[Quaternary ammonium salt]
Octadecyltrimethylammonium bromide (Catinal STB, manufactured by Toho Chemical Co., Ltd.)

[Examples 1-5, Comparative Examples 1-6]
An acrylic rubber composition was prepared by blending the above components in the proportions shown in Tables 2 and 3 below and kneading them using a 5 L kneader.

  The rubber compositions of Examples and Comparative Examples thus obtained were extruded into a tubular (cylindrical) shape with an inner diameter of 45 mm and a wall thickness of 5 mm, then cut into a length of 100 mm, and a straight metal having an outer diameter of 45 mm. A mandrel was interpolated. And after performing steam vulcanization | cure for 160 degreeC x 60 minutes, it extracted from the metal mandrel, and also performed secondary vulcanization in oven at 150 degreeC for 8 hours, and obtained the rubber hose. With respect to this rubber hose, each characteristic was evaluated according to the following criteria. These results are shown in Tables 2 and 3 below.

[Hose / pipe pulling force]
A metal pipe (outer diameter 45 mm) was inserted 35 mm into both ends of each hose, and then fastened with a worm clamp to obtain an evaluation sample. Next, the evaluation sample was fixed to an autograph, the metal pipe inserted at both ends of the hose was pulled, and the maximum load until the metal pipe was pulled out was read. And the thing whose said maximum load is 3500N or more evaluated the thing which is (circle) and less than 3500N as x.

〔Heat-resistant〕
Using an acrylic rubber composition that is a material of each hose, an unvulcanized rubber sheet having a thickness of 2 mm was produced by a 6-inch mixing roll, and this was press vulcanized at 160 ° C. × 60 minutes, and then further 150 ° C. × Oven vulcanization for 8 hours was applied. Subsequently, a JIS No. 5 dumbbell was punched out from this rubber sheet, and the dumbbell was subjected to heat aging at 175 ° C. for 750 hours, and then subjected to an external appearance evaluation to determine whether there was any abnormality such as bending or cracking by 180 °. The dumbbells with no abnormality were evaluated as ◯, and those with abnormality were evaluated as x.

[Low temperature]
Each hose was cut into a 30 mm width and used as an evaluation sample. That is, the evaluation sample was allowed to stand in an atmosphere of −35 ° C. for 5 hours, then sandwiched between two flat plates in the diameter direction, and compressed within 4 seconds until reaching 50% of the hose outer diameter. And the thing which a crack did not produce to the evaluation sample was evaluated as (circle), and the thing which a crack produced was evaluated as x.

  From the above results, it can be seen that the hose of the example is excellent in heat resistance and low temperature property and has a high hose / pipe pulling force. Therefore, it has excellent resistance to coming off from the hose base.

  On the other hand, the hose of Comparative Example 1 was inferior in low-temperature properties because the proportion of the ether / ester plasticizer in the material (acrylic rubber composition) was too small. In the hose of Comparative Example 2, the ratio of the ether / ester plasticizer in the material was too large, and the plasticizer oozed out on the inner peripheral surface of the hose, resulting in inferior hose / pipe pull-out force evaluation. Although the hose of Comparative Example 3 has a small plasticizer content in the material, since only the ether / ester plasticizer is used as the plasticizer, the plasticizer bleeds on the inner peripheral surface of the hose, The hose / pipe pull-out force evaluation was inferior. Since the hose of Comparative Example 4 did not contain an ether / ester plasticizer in the material, the result was inferior in low-temperature properties. The hose of Comparative Example 5 was inferior in heat resistance because the acrylic acrylate polymer material was too low in ethyl acrylate content. The hose of Comparative Example 6 had too much ethyl acrylate content in the acrylic polymer as the material, resulting in inferior hose / pipe pull-out force evaluation.

  The heat-resistant hose of the present invention is particularly suitably used as an air-based hose through which high-temperature air flows, such as a turbo air hose (supercharger air hose). It can also be used as a fuel hose that requires heat resistance. And the said heat-resistant hose is used suitably for transport machines, such as a motor vehicle, a tractor, a cultivator, and a ship.

Claims (2)

A heat-resistant hose comprising at least one constituent layer, the innermost layer comprising an acrylic rubber composition having the following (A) as a main component and the following (B) as a plasticizer component hose.
(A) An acrylic polymer obtained by copolymerizing an acrylic ester component and a crosslinkable monomer , wherein the acrylic ester component is composed of ethyl acrylate (EA) and butyl acrylate (BA), and its weight ratio Is an acrylic polymer in which EA: BA = 4: 6 to 8: 2.
(B) A plasticizer comprising an ether / ester plasticizer and an ester plasticizer, the weight ratio of which is ether / ester plasticizer: ester plasticizer = 3: 7 to 7: 3.   The heat-resistant hose according to claim 1, wherein the content ratio of the component (B) in the acrylic rubber composition is in the range of 5 to 50 parts by weight with respect to 100 parts by weight of the component (A).