JP7033309B2 - Resin-rubber laminate and refrigerant transport hose - Google Patents

Description

The present invention relates to a resin-rubber laminate and a refrigerant transport hose.

In Patent Document 1, as a refrigerant transport hose used for automobiles and the like, the innermost layer is formed from a composition containing an aliphatic polyamide resin, an aromatic amine-based hydrolysis inhibitor and a phosphorus-based hydrolysis inhibitor. It is described that the refrigerant transport hose provided with a rubber layer on the outer layer is excellent in refrigerant / refrigerating machine oil resistance, refrigerant permeability resistance, and flexibility.
Further, Patent Document 2 describes a refrigerant transport hose having an inner layer having a two-layer structure made of polyamide, in which the inner polyamide layer contains an organic antioxidant and the outer polyamide layer is organic. It is stated that it does not contain antioxidants.

Japanese Unexamined Patent Publication No. 2017-155764 Japanese Unexamined Patent Publication No. 2012-189129

According to the invention described in Patent Document 1, it is required to use an aromatic amine-based hydrolysis inhibitor and a phosphorus-based hydrolysis inhibitor in combination, and the layer to which these are added is an inner layer of polyamide. A refrigerant transport hose in which an outer layer made of a rubber layer is formed on the outer side of the inner layer of the polyamide. At this time, the refrigerating machine oil flowing together with the refrigerant in the refrigerant transport hose may be discolored due to the general anti-aging agent contained in the outer layer, although the reason is unknown.
Further, according to the invention described in Patent Document 2, since the inner layer of the refrigerant transport hose contains an organic antioxidant, the organic system contained in the inner layer as it comes into direct contact with the refrigerant and the refrigerating machine oil. Anti-aging agents can discolor refrigerating machine oil.
And even if the inner layer does not contain an anti-aging agent or the like in order to prevent the refrigerating machine oil from discoloring, the cause is unknown, but there is still the effect of the anti-aging agent contained in the outer layer. , Refrigerating machine oil may be discolored.
The present invention is a resin-rubber laminate used in a refrigerant transport device that does not discolor refrigerating machine oil, and further has sufficient characteristics as a refrigerant transport hose even in direct contact with a refrigerant or refrigerating machine oil. The challenge is to obtain a hose that does not discolor the refrigerating machine oil.

In order to solve the above problems, the present invention has adopted the following configuration.
1. 1. Polyamide layer and
The polyamide layer has an EOM and / or an EPM-containing layer on one side thereof, and has an EOM and / or an EPM-containing layer.
The EOM and / or EPM-containing layer is
0.5 to 1.5 parts by weight of EOM and / or EPM with respect to 100 parts by weight of an aromatic secondary amine-based antiaging agent.
0.2-1.0 parts by weight of benzimidazole-based antioxidant with respect to 100 parts by weight of EOM and / or EPM.
0.5-5.0 parts by weight of co-crosslinking agent with respect to 100 parts by weight of EOM and / or EPM.
1.0 to 9.0 parts by weight of liquid polymer with respect to 100 parts by weight of EOM and / or EPM.
A resin-rubber laminate characterized by containing.
2. 2. The aromatic secondary amine-based antioxidant is 4,4'-bis (α, α-dimethylbenzyl) diphenylamine, and the benzimidazole-based antioxidant is 2-mercaptobenzimidazole. The resin-rubber laminate according to 1.
3. 3. A refrigerant transport hose having the structure of the resin-rubber laminate according to 1 or 2 above, wherein the polyamide layer side is an inner layer and the EOM and / or EPM-containing layer side is an outer layer.

According to the present invention, the resin-rubber laminate to which the refrigerant and the refrigerating machine oil come into direct contact and the refrigerant transport hose can have sufficient mechanical strength and excellent adhesive strength between the two layers. In addition, when the refrigerant or refrigerating machine oil and the polyamide layer side are in direct contact with each other as a resin-rubber laminate or as a refrigerant transport hose, the refrigerant or refrigerating machine oil is not in direct contact with the polyamide layer, but the refrigerant or refrigerating machine oil. When viewed from the machine oil side, the EOM and / or EPM layer, which is the outer layer, contains the aromatic secondary amine-based antioxidant and the benzimidazole-based antioxidant, so that the resin of the polyamide layer, which is the inner layer, can be obtained. It does not deteriorate and does not discolor the refrigerating machine oil. As for this deterioration, not only the deterioration due to the continuous use of the resin-rubber laminate that comes into direct contact with the refrigerant and the refrigerating machine oil and the hose for transporting the refrigerant, but also the deterioration before use (due to heating at the time of cross-linking, etc.) is targeted. There is.
Therefore, the refrigerant and the refrigerating machine oil can be used for a sufficiently long period of time without replacement.

The present invention is a refrigerant transport hose based on a laminate having a polyamide layer and an EOM and / or EPM-containing layer, further having an inner layer made of a polyamide layer and an outer layer made of an EOM and / or EPM-containing layer. ..
Hereinafter, preferred embodiments of the present invention will be described in detail.

[Polyamide layer]
Examples of the polyamide used for the polyamide layer in the present invention include polyamide 46 (PA46), polyamide 6 (PA6), polyamide 66 (PA66), polyamide 610 (PA610), polyamide 612 (PA612), and polyamide 1010 (PA1010) polyamide 6. (PA6) and polyamide 66 (PA66) copolymer, polyamide 11 (PA11), polyamide 12 (PA12), polyamide 11 (PA11) and polyamide 12 (PA12) copolymer, modified product and the like can be used. ..
The polyamide layer may be one layer or may be formed from a plurality of layers.
It is necessary that the polyamide layer does not contain components that adversely affect the refrigerating machine oil, such as deteriorating or discoloring the refrigerating machine oil in view of direct contact with the refrigerating machine oil.
Therefore, it is desirable not to add an antiaging agent having such an adverse effect, and it is desirable not to add an aromatic amine-based antiaging agent and / or a benzimidazole-based antiaging agent. However, an aromatic amine-based anti-aging agent, a benzimidazole-based anti-aging agent, a phenol-based anti-aging agent, a dithiocarbamate-based anti-aging agent, a thiourea-based anti-aging agent, etc. An organic thioic acid-based anti-aging agent and a phobic acid-based anti-aging agent can be blended.
Further, various additives known to be added to the polyamide resin, for example, carbon black, a filler, a co-crosslinking agent, and cross-linking promotion, within a range that does not impair the effect of the present invention and do not adversely affect the refrigerating machine oil. Agents, cross-linking aids, softeners, plasticizers, stabilizers, processing aids and the like can be added as appropriate.

[EOM and / or EPM-containing layer]
The EOM-containing layer is an ethylene-octane rubber-containing layer, and the EPM-containing layer is an ethylene-propylene rubber-containing layer. Further, it may be used as a layer containing a blend of EOM and EPM. The EOM and / or EPM-containing layer can be independently formed from a plurality of layers as long as the properties of the EOM and / or EPM-containing layer are not changed.
In addition, halogenated butyl rubber such as butyl rubber (IIR), chlorinated butyl rubber (Cl-IIR), brominated butyl rubber (Br-IIR), acrylonitrile-butadiene rubber (NBR), and chloroprene, as long as the effects of the present invention are not impaired. It is possible to blend rubber (CR), ethylene-propylene-diene rubber (EPDM), fluororubber (FKM), epichlorohydrin rubber (ECO), acrylic rubber, silicone rubber, chlorinated polyethylene rubber (CPE), urethane rubber, etc. can.

[Aromatic secondary amine-based antiaging agent]
The EOM and / or EPM-containing layer contains an aromatic secondary amine-based antiaging agent.
Examples of the aromatic secondary amine-based antiaging agent include phenyl-α-naphthylamine, alkylated diphenylamine, octylated diphenylamine, 4,4'-bis (α, α-dimethylbenzyl) diphenylamine, phenothiazine derivative, and ρ- ( ρ-Toluenesulfonylamide) diphenylamine, N, N'-di-2-naphthyl-ρ-phenylenediamine, N, N'-diphenyl-ρ-phenylenediamine, N-phenyl-N'-isopropyl-ρ-phenylenediamine, N-Phenyl-N'-(1,3-dimethylbutyl) -ρ-phenylenediamine, N-phenyl-N'-(1-methylheptyl) -ρ-phenylenediamine, N-phenyl-N'-(3-) Methacloyloxy-2-hydroxypropyl) -ρ-phenylenediamine may be used alone or in combination of two or more.
The blending amount of the aromatic secondary amine-based antiaging agent is 0.5 to 1.5 parts by weight with respect to 100 parts by weight of EOM and / or EPM. If the blending amount is less than 0.5 parts by weight, the polyamide resin layer of the inner layer is deteriorated, and if it exceeds 1.5 parts by weight, the refrigerating machine oil is discolored.

[Benzimidazole antiaging agent]
The EOM and / or EPM-containing layer contains a benzimidazole-based anti-aging agent together with the above aromatic secondary amine-based anti-aging agent.
Examples of benzimidazole-based antiaging agents include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, 2-mercaptobenzimidazole and phenol condensate mixture, 2-mercaptobenzimidazole metal salt, and 2-mercaptomethylbenzimidazole. Examples thereof include metal salts of 5-mercaptomethylbenzimidazole and metal salts of 5-mercaptomethylbenzimidazole.
The blending amount of the benzimidazole-based antiaging agent is 0.2 to 1.0 part by weight with respect to 100 parts by weight of EOM or EPM.
If the blending amount is less than 0.2 parts by weight, the polyamide resin layer of the inner layer is deteriorated, and if it exceeds 1.0 part by weight, the refrigerating machine oil is discolored.

[Other anti-aging agents]
In the EOM and / or EPM-containing layer, as other antioxidants, phenolic antioxidants such as 2,5-di- (t-amyl) -hydroquinone and 2,5-di-t-butylhydroquinone, diethyl. Nickel dithiocarbamate, nickel dimethyldithiocarbamate, nickel dibutyldithiocarbamate, nickel diisobutyldithiocarbamate, copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper N-ethyl-N-phenyldithiocarbamate, N-pentamethylene dithiocarbamine Dithiocarbamate-based antiaging agents such as copper acid and dibenzyldithiocarbamate copper, thiourea-based antiaging agents such as 1,3-bis (dimethylaminopropyl) -2-thiourea and tributylthiourea, dilaurylthio Dipropionate, distearyl thiodipropionate, dimyristyl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, pentaerythritol-tetrakis- (β-lauryl-thiopropionate) ), Organic thioacid-based antioxidants such as dilauryl thiodipropionate, tris (nonylphenyl) phosphite, tris (mixed mono- and di-nonylphenyl) phosphite, diphenyl mono (2-ethylhexyl) phosphite. , Diphenyl, monotridecyl, phosphite and other hydroquinone-based antiaging agents can be blended within a range that does not impair the effects of the present invention.

[Crosslinking agent]
In order to obtain the refrigerant transport hose of the present invention, a cross-linking agent may be added to the EOM and / or EPM-containing layer, laminated with the inner layer, and then cross-linked.
Examples of the cross-linking agent include benzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 1,1'-di- (t-butylperoxy) -diisopropylbenzene, and n. -Organic peroxides such as butyl-4,4-di (t-butylperoxy) valerate and 1,1-di (t-butylperoxy) cyclohexane may be added to the extent that the effects of the present invention are not impaired. can.
In the uncrosslinked state, the content of the cross-linking agent in the EOM and / or EPM-containing layer with respect to 100 parts by weight of EOM or EPM is 1.5 parts by weight or more, preferably 2 parts by weight or more. If the content is less than 1.5 parts by weight, the mechanical strength is likely to be inferior.

[Co-crosslinking agent]
Examples of the co-crossing agent that may be blended in the EOM and / or EPM-containing layer in the present invention include triallyl cyanurate, triallyl isocyanurate, trimetalyl isocyanurate, ethylene glycol dimethacrylate, and trimethylolpropanetrimethacrylate, 1 , 2-Polybutadiene, Magnesium Acrylic Acid, Zinc Acrylic Acid, Magnesium Methacrylate, Zinc Methacrylate, Hexamethylene Diamine Carbamate, P-Kinone Dioxime, P, P'-Dibenzoylquinone Dioxime, N, N'-m- Examples thereof include phenylene bismaleimide and amylphenol disulfide polymer, and it is preferable to use triallyl isocyanurate.
The blending amount of the co-crosslinking agent is 0.5 to 5.0 parts by weight with respect to 100 parts by weight of EOM or EPM. If it is less than 0.5 parts by weight, the mechanical strength is low, and if it exceeds 5.0 parts by weight, the adhesive strength between the inner layer and the outer layer is lowered.

[Carbon black]
For the EOM and / or EPM-containing layer in the present invention, carbon black known to be added to the rubber composition can be arbitrarily selected and used.

[glue]
An adhesive can be added to the EOM and / or EPM-containing layer.
Such adhesives are generally liquid polymers and, for example, modified liquid polymers include hydroxy group modified polymers such as hydroxy group terminal modified polyisoprenes and their hydrogenated additives; epoxy group modified polymers such as epoxy group modified polybutadienes. (Meta) acrylate group-modified polymers such as acrylate-modified polybutadiene; Hydrolytable silicon group-containing polymers such as silane graft polyolefins and silane-terminated polyolefins; Maleic anhydride-modified polyisoprene, Maleic anhydride-modified polybutadiene, Maleic anhydride-modified polybutene, Acid anhydride-based modified polymers such as maleic anhydride-modified ethylene-propylene copolymer and maleic anhydride-modified ethylene α-olefin copolymer; carboxy-modified polybutadiene, carboxy-modified polyisoprene, carboxy-terminated acrylonitrile-butadiene copolymer (CTBN) and the like. Carboxy group-modified polymer; an amino group-modified polymer such as an amino group-terminated acrylonitrile butadiene copolymer (ATBN).
The blending amount of the adhesive is 1.0 to 9.0 parts by weight with respect to 100 parts by weight of EOM or EPM. If it is less than 1.0 part by weight, the adhesive force between the inner layer and the outer layer becomes low, and if it exceeds 9.0 parts by weight, the releasability from the mold after vulcanization deteriorates.

[Crosslinking aid]
For the EOM and / or EPM-containing layer in the present invention, a cross-linking aid known to be added to the rubber composition can be arbitrarily selected and used. Specific examples include 1,2-polybutadiene, magnesium acrylate, zinc acrylate, magnesium methacrylate, zinc methacrylate, hexamethylenediaminecarbamate, P-quinonedioxime, P, P'-dibenzoylquinonedioxime, N, Examples thereof include N'-m-phenylene bismaleimide, amylphenol disulfide polymer and the like, and it is preferable to use triallyl isocyanurate.

Various additives known to be added to other rubbers and resins, and rubber compositions, for example, as long as the characteristics as an EOM and / or EPM-containing layer are not lost and the effect of the present invention is not impaired. , Fillers, cross-linking promoting aids such as zinc oxide, softeners, plasticizers, stabilizers, processing aids such as stearic acid, and the like can be appropriately added.

[Structure of resin member that comes into direct contact with refrigerant and refrigerating machine oil]
The laminate of the present invention can be used as a resin member that comes into direct contact with a refrigerant or refrigerating machine oil. As such a resin member, other than the following refrigerant transport hose, packing, a constituent member or repair member of a refrigerant transport device, a refrigerant container, or a material for these members can be used.
Then, the laminated body which is these resin members can be obtained by molding by a known molding means and conditions according to each shape.

[Structure of refrigerant transport hose]
In the refrigerant transport hose of the present invention, the polyamide layer side is the inner layer, and the EOM and / or EPM-containing layer is the outer layer.
By using the polyamide layer side as the inner layer, even if the refrigerant or the refrigerating machine oil flows through the hose for transporting the refrigerant, the polyamide layer does not deteriorate or the refrigerating machine oil does not discolor.
The pressure resistance, weather resistance, etc. are improved by further providing a reinforcing layer made of organic or inorganic fibers, a weather resistant rubber layer, etc. on the outer surface of the EOM and / or EPM-containing layer of the refrigerant transport hose of the present invention. Can be made to.
As the cross-sectional shape, the inner surface of the inner layer and the outer surface of the outer layer can be independently formed into arbitrary shapes such as a circle, an ellipse, and a square.
The thickness of the inner layer of the present invention is 0.1 to 0.3 mm, the thickness of the outer layer is 1 to 3 mm, the inner diameter of the hose of the present invention is 7 to 18 mm, and the outer diameter of the hose is 14 to 26 mm.

[Manufacturing method of refrigerant transport hose]
As a method for manufacturing the hose for transporting a hose of the present invention, the polyamide layer of the present invention and the EOM and / or EPM-containing layer are extruded on the outer periphery of the mandrel by extrusion molding with a two-layer extruder or the like to form a cylindrical shape for the hose. A method can be adopted in which a fiber reinforcing layer and an outermost rubber layer are formed on the outer periphery thereof, and the laminated body is heated to crosslink the laminate.
Alternatively, the resin composition for the polyamide layer is formed into a cylindrical shape for the innermost layer side of the flexible hose by extrusion molding, and then the rubber composition for the EOM and / or EPM-containing layer is formed into a cylinder for the second layer by extrusion molding. After being formed into a shape and laminated on the outer periphery of the polyamide layer, the rubber laminate is crosslinked by heating under conditions selected from known crosslinking conditions. As a result, the cross-linking agent such as organic peroxide contained in the uncross-linked rubber laminate is consumed, and most of the cross-linking agent does not remain in the cross-linked rubber laminate.
After the extrusion molding (lamination) step or the crosslinking step, a fiber reinforcing layer and an outermost rubber layer are placed on the outer periphery of the EOM and / or EPM-containing layer for the purpose of improving strength, if necessary. It may be formed.
Further, the refrigerant transport hose may be a flexible hose having vibration absorption characteristics. When a flexible hose is used, it can be used as an air conditioner hose for a vehicle, for example.
Further, when such a hose is used as a resin member in contact with a refrigerant or refrigerating machine oil, the refrigerant includes HFC-134a, 152a, 32, 143a, 125, HFO-1234yf, etc., and these. Can be used for equipment for fluorocarbon-based refrigerants consisting of a mixture of.
Further, as the refrigerating machine oil, at least one selected from the group consisting of polyalkylene glycol (PAG), polyol ester (POE) and the like can be used.

Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these.
A rubber composition for an EOM layer and an EPM layer containing each component shown in Table 1 below was obtained, and one of these compositions was used as an outer layer, and a separately prepared resin composition for a PA6 layer was used as an inner layer. A molded body for a hose for transporting a refrigerant before crosslinking was molded.
Next, this molded product was heat-crosslinked to obtain a refrigerant transport hose, and the deterioration status of the inner surface resin of the refrigerant transport hose and the discoloration status of the refrigerating machine oil were evaluated under the evaluation conditions shown below.
In order to simplify the evaluation, the mechanical strength (modulus) and the releasability from the mold are evaluated only by the rubber composition for the EOM layer or the EPM layer, and the PA6 layer and the EOM layer or the EPM layer are adhered to each other. The properties were evaluated with a laminate of the resin composition for the PA6 layer and the rubber composition for the EOM layer or the EPM layer.

(Mechanical strength (modulus))
An uncrosslinked EOM and EPM rubber sheet (rubber composition) having a thickness of 2 mm were crosslinked by press heating, and then a dumbbell-shaped No. 3 test piece specified by JIS K6251 was prepared.
100% elongation tensile stress (M100) was evaluated based on the following criteria according to JIS K6251 "Vulcanized rubber and thermoplastic rubber-How to determine tensile properties".
◯: 5.0 MPa or more ×: less than 5.0 MPa

(Adhesion between PA6 layer and EOM layer or EPM layer)
A 0.15 mm thick PA6 resin sheet and a 2 mm thick uncrosslinked EOM or EPM rubber sheet are crosslinked and adhered by press heating, and then cut into dimensions of 10 mm in width × 100 mm in length to prepare a test piece. did.
According to JIS K6256-1 "Vulcanized rubber and thermoplastic rubber-How to determine adhesiveness-Part 1: Peeling strength with cloth", peel off by 90 ° at a peeling speed of 50 mm / min, and follow the criteria below. Adhesive strength was evaluated based on this.
◯: 3.9 N / mm or more ×: less than 3.9 N / mm

(Deterioration of resin on the inner surface of the hose)
The oxidation start temperature (ITO) of the inner surface resin (PA6) collected from the hose under normal conditions was measured by a differential scanning calorimeter (DSC), and the deterioration state was evaluated based on the following criteria.
◯: Temperature difference from the normal state (265 to 275 ° C) of the current product <-10 ° C ×: Temperature difference from the normal state (265 to 275 ° C) of the current product -10 ° C or more

(Discoloration of refrigerating machine oil)
Mouth fittings are attached to both ends of the hose cut to a predetermined length, the hose is sealed with refrigerating machine oil (PAG) filled, and left in an environment of 150 ° C for 168 hours. The discoloration situation was evaluated based on.
○: Equivalent to or less than the discoloration level of the current product ×: Greater than the discoloration level of the current product

(Releasability from mold)
After cross-linking an uncrosslinked EOM and EPM rubber sheet (rubber composition) having a thickness of 2 mm by press heating, when the rubber sheet was taken out from the mold, the releasability was evaluated based on the following criteria.
○: No sticking to the mold △: Sticking to the mold (removable)
×: Sticking to the mold (cannot be taken out)

According to the results of each example, the reason is unknown, but the refrigerating machine oil is obtained by blending a specific antiaging agent with the outer layer which is the EOM layer or the EPM layer which is not in direct contact with the refrigerant or the refrigerating machine oil. I was able to demonstrate the effect of being able to prevent discoloration. Further, it can be seen that the same effect can be exhibited regardless of whether EOM or EPM is adopted.
On the other hand, according to Comparative Example 1 containing no co-crosslinking agent, the mechanical strength was inferior, and according to Comparative Example 2 in which the content of the co-crosslinking agent was too large, between the PA6 layer and the EOM layer. The result was that the adhesive strength was inferior. Further, according to Comparative Example 3 which does not contain an anti-aging agent, the resin of the inner layer is deteriorated and the mold release property from the mold at the time of molding is slightly inferior, and the comparison does not contain the benzimidazole-based anti-aging agent. According to Example 4 and Comparative Example 5 which does not contain an aromatic secondary amine-based anti-aging agent, the resin in the inner layer is deteriorated, and according to Comparative Example 6 in which the content of the anti-aging agent is too large, the refrigerating machine oil is used. The result was that discoloration occurred and the mold releasability from the mold at the time of molding was slightly inferior. Further, according to Comparative Example 7 which does not contain the adhesive which is a liquid polymer, the adhesive strength between the PA6 layer and the EOM layer is inferior, and the content of the adhesive which is a liquid polymer is too large in Comparative Example 8. According to this, the result was that the mold releasability from the mold at the time of molding was slightly inferior.
Further, particularly considering the results of Comparative Examples 4 and 5 and particularly the results of Examples 5 and 6, it is remarkable that deterioration of the resin in the inner layer can be prevented by using these two kinds of antioxidants in combination. It can be seen that it is effective.

Claims (3)

A polyamide layer that comes into contact with refrigerating machine oil during use ,
The polyamide layer has an EOM and / or an EPM-containing layer on one side thereof, and has an EOM and / or an EPM-containing layer.
The EOM and / or EPM-containing layer is
0.5 to 1.5 parts by weight of EOM and / or EPM with respect to 100 parts by weight of an aromatic secondary amine-based antiaging agent.
0.2-1.0 parts by weight of benzimidazole-based antioxidant with respect to 100 parts by weight of EOM and / or EPM.
0.5-5.0 parts by weight of triallyl isocyanurate with respect to 100 parts by weight of EOM and / or EPM.
1.0 to 9.0 parts by weight of EOM and / or 100 parts by weight of EPM, acid anhydride-based modified polymer,
A resin-rubber laminate characterized by containing. The aromatic secondary amine-based antioxidant is 4,4'-bis (α, α-dimethylbenzyl) diphenylamine, and the benzimidazole-based antioxidant is 2-mercaptobenzimidazole. The resin-rubber laminate according to claim 1. A refrigerant transport hose having the structure of the resin-rubber laminate according to claim 1 or 2, wherein the polyamide layer side is an inner layer and the EOM and / or EPM-containing layer side is an outer layer. ..