JP5092724B2 - Laminated resin tubular body for hose inner pipe and refrigerant transport hose - Google Patents

Description

  The present invention is excellent in flexibility, gas barrier properties, and moisture resistance. By using this as the innermost layer of a refrigerant transport hose, gas barrier properties (refrigerant permeability), dynamic durability (vibration durability), flexibility The present invention also relates to a laminated resin tubular body for a hose inner tube that can provide a refrigerant transportation hose excellent in moisture resistance, and a refrigerant transportation hose having the laminated resin tubular body for a hose inner tube.

  Conventionally, CFCs such as HFC-134a (R-134a) have been used as refrigerants in automobile air conditioners.

From the viewpoint of improving ride comfort, a rubber hose having excellent vibration absorption performance is used for the piping of this automobile air conditioner.
The rubber hose has a structure in which a nylon resin layer with excellent gas barrier properties and excellent vibration durability such as impulse resistance is disposed on the innermost layer to prevent refrigerant leakage, and an inner tube rubber layer is provided thereon. Is used, and a reinforcing yarn layer made of organic fibers such as PET is provided thereon, and an EPDM rubber layer having weather resistance is further provided thereon.

  In recent years, environmental problems have been greatly taken up, and the global warming potential of Freon gas R-134a, which is used as a refrigerant in automobile air conditioners, is becoming a problem. The current Freon gas R-134a has a global warming potential of nearly 1500 although its ozone depletion coefficient is zero, and a significant reduction in the amount of leakage has been demanded.

  In response to this trend, a new fluorination gas emission regulation proposal was adopted by the EU around mid-2003, and automobile OE companies became a major concern for the significant reduction of refrigerant leakage.

  The next-generation refrigerant is required to have a global warming potential of 150 or less. As an alternative refrigerant satisfying this numerical value, a Freon system is considered, and newly developed mixed refrigerants such as R-152a and Fluid-H are considered promising. R-152a is required to have higher permeation resistance than the hose because the hose permeation amount under the same conditions is as high as four times that of R-134a. In addition, although mixed refrigerants such as Fluid-H are said to exhibit azeotropic properties, the permeation coefficients for the hose for each component differ greatly, and the composition of the refrigerant changes greatly during use, so-called selective permeation. There's a problem. At present, it is difficult to suppress the selective permeation itself, so it is considered effective to reduce the composition change of the remaining refrigerant by suppressing the total permeation amount. That is, in any new freon refrigerant, a hose having excellent permeation resistance is required.

  On the other hand, as an ultimate refrigerant, there is a carbon dioxide refrigerant having a global warming potential = 1.0. However, in order for carbon dioxide gas to function as a refrigerant, a supercritical state is required, and more severe high heat resistance / high pressure resistance is required for the hose. In addition, since the gas permeation amount increases remarkably as the temperature and pressure increase, carbon dioxide refrigerants are required to have a significant improvement in gas barrier properties as well as freon refrigerants.

In order to solve this problem, the present applicant has previously proposed an EVOH composite resin and a refrigerant transport hose excellent in gas barrier properties and flexibility (Japanese Patent Laid-Open No. 2007-9171). This refrigerant transport hose has a multi-layer structure composed of a composite resin layer and a polyamide resin layer, which are made flexible by blending an elastomer with an ethylene / vinyl alcohol copolymer with excellent gas barrier properties. The gas barrier property is greatly improved while maintaining the repeated pressurization property (impulse property).
JP 2007-9171 A

The refrigerant transport hose described in JP-A-2007-9171 is excellent in gas barrier properties, flexibility and durability, but further improvement is desired.
That is, the internal fluid of the refrigerant transport hose is the refrigerant and compressor lubricant, but the current Freon gas R-134a and the compressor lubricant polyalkylene glycol (PAG) both have high hydrophilicity and absorb moisture. Cheap. When these internal fluids absorb moisture and the moisture content in the air conditioning system increases, the expansion valve may freeze and cause clogging of the piping. Therefore, it is desired that the refrigerant transport hose is excellent in moisture permeability resistance in addition to flexibility, durability, and gas barrier properties.
In addition, Freon and carbon dioxide, which are alternative materials for conventional chlorofluorocarbons, have higher hydrophilicity than chlorofluorocarbons. Therefore, these hoses for alternative materials are also required to have high moisture resistance and water resistance, which are not conventional.

  The present invention has been made in view of the above-described conventional situation, and is excellent in gas barrier properties (refrigerant permeability), dynamic durability (vibration durability), flexibility, and moisture resistance (moisture resistance permeation). The present invention aims to provide a laminated resin tubular body for a hose inner pipe excellent in water resistance and a refrigerant transport hose having the laminated resin tubular body for a hose inner pipe.

  As a result of intensive studies to solve the above problems, the present inventor has found that an inner circumference side of a layer made of an EVOH composite resin containing an ethylene / vinyl alcohol copolymer excellent in gas barrier properties and flexibility and an elastomer, and / or Or, by laminating a layer made of a polyester / polyether copolymer with high moisture resistance and water resistance on the outer peripheral side, while maintaining the gas barrier properties and flexibility of the EVOH composite resin layer, the moisture resistance and water resistance Has been found to be further improved, and the present invention has been completed.

  Polyamide / polyether copolymers may be used as resins excellent in moisture-resistant layers (moisture-resistant layers), but the polyester / polyether copolymers used in the present invention are more suitable than polyamide / polyether copolymers. Excellent moisture-resistant layer (moisture-resistant layer). However, when a polyamide / polyether copolymer is used, good adhesion can be obtained by co-extrusion with an EVOH composite resin. However, polyester / polyether copolymer provides sufficient adhesion by co-extrusion. Therefore, it is essential to interpose an adhesive layer between the EVOH composite resin layer and the polyester / polyether copolymer layer.

The laminated resin tubular body for a hose inner pipe of the present invention (invention 1) is a laminated resin tubular body for a hose inner pipe provided with a layer made of an EVOH composite resin containing an ethylene / vinyl alcohol copolymer and an elastomer, An average acid value of the whole elastomer is 1.5 to 7.5 mg-CH ₃ ONa / g, and a polyamide based composite resin containing polyamide and an ethylene propylene copolymer on the inner peripheral side of the EVOH composite resin layer The layers are laminated, and a layer made of a polyester / polyether copolymer is laminated on the outer peripheral side through an adhesive layer.

  The laminated resin tubular body for a hose inner pipe according to claim 2 is characterized in that, in claim 1, the elastomer content of the EVOH composite resin is 10 to 40% by weight.

  The laminated resin tubular body for a hose inner pipe according to claim 3 is characterized in that, in claim 2, the elastomer is a modified elastomer or a mixture of a modified elastomer and an unmodified elastomer.

  A laminated resin tubular body for a hose inner pipe according to claim 4 is characterized in that, in any one of claims 1 to 3, the modified elastomer content of the EVOH composite resin is 5 to 20% by weight. It is.

The laminated resin tubular body for an inner tube of a hose according to claim 5 is characterized in that, in claim 3 or 4 , the acid value of the modified elastomer is ₃ to 15.0 mg-CH3ONa / g.

A laminated resin tubular body for a hose inner pipe according to claim 6 is the laminate according to any one of claims 1 to 5 , wherein the EVOH-based composite resin layer is composed of a sea phase made of an ethylene / vinyl alcohol copolymer and an island made of an elastomer. It has a sea-island structure having a phase, and an ethylene-vinyl alcohol copolymer is dispersed in the form of dots in the island phase of the elastomer.

The laminated resin tubular body for an inner tube of a hose according to claim 7 is characterized in that, in any one of claims 1 to 6 , the ethylene content of the ethylene-vinyl alcohol copolymer is 28 to 40 mol%. Is.

The laminated resin tubular body for hose inner pipe according to claim 8 is characterized in that in any one of claims 1 to 7 , the adhesive layer contains a modified polyolefin resin.

A refrigerant transport hose according to the present invention (invention 9 ) has the laminated resin tubular body for a hose inner tube according to any one of claims 1 to 8 .

The refrigerant transport hose according to claim 10 is characterized in that, in claim 9 , a reinforcing layer made of a reinforcing thread and a jacket rubber layer are provided on the outer peripheral side of the laminated resin tubular body for a hose inner tube. Is.

  The laminated resin tubular body for a hose inner pipe of the present invention is excellent in gas barrier properties, flexibility, and resistance to repeated pressurization, as well as moisture permeability and water resistance. For this reason, the refrigerant transport hose of the present invention provided with this laminated resin tubular body for an inner tube of a hose can sufficiently cope with a highly hydrophilic internal fluid, and has high reliability without causing a problem due to moisture permeation. It can be used over a long period of time.

  In this invention, it is preferable that the elastomer content rate of the said EVOH type composite resin is 10 to 40 weight%. By setting the elastomer content to 10 to 40% by weight, an EVOH composite resin layer having excellent gas barrier properties, flexibility, and durability can be obtained.

  In the present invention, the elastomer is preferably a modified elastomer or a mixture of a modified elastomer and an unmodified elastomer, and the EVOH composite resin preferably contains 5 to 20% by weight of the modified elastomer. When the modified elastomer content of the EVOH-based composite resin is 5 to 20% by weight, the improvement effect of the kneadability and alloy structure due to the blending of the modified elastomer is obtained, and the appearance defect such as rough skin during the extrusion (fish) Eye) can be prevented.

As this modified elastomer, one having an acid value of ₃ to 15 mg-CH ₃ ONa / g is used, and the average acid value of the whole elastomer is 1.5 to 7.5 mg-CH ₃ ONa / g. Is preferred. When such a composition is used, the compatibility between the ethylene / vinyl alcohol copolymer and the elastomer is improved, and the increase in viscosity is suppressed, so that the moldability is also improved.

  Hereinafter, embodiments of the laminated resin tubular body for a hose inner pipe and the refrigerant transport hose of the present invention will be described in detail.

  The laminated resin tubular body for an inner tube of a hose of the present invention is formed by laminating a layer made of a polyester / polyether copolymer on an inner peripheral side and / or outer peripheral side of a layer made of EVOH composite resin via an adhesive layer. It is.

First, the EVOH composite resin used in the present invention will be described.
The EVOH composite resin used in the present invention is a polymer alloy obtained by adding an elastomer as a flexibility-imparting agent to an ethylene / vinyl alcohol copolymer.

  The ethylene / vinyl alcohol copolymer has an ethylene / vinyl alcohol composition ratio of a large amount of ethylene. If the amount of vinyl alcohol is small, its properties are close to that of polyethylene and its flexibility is improved, but the melting point is lowered and the gas barrier property is impaired. It is. On the contrary, when ethylene is small and vinyl alcohol is large, the flexibility is impaired, but the melting point is increased and the gas barrier property is greatly improved. Therefore, the ethylene content is preferably about 28 to 40 mol%.

  As the ethylene / vinyl alcohol copolymer, one kind may be used alone, or two or more kinds having different molecular weights and composition ratios may be used in combination.

  As the elastomer, α-olefin-based elastomers are preferable. For example, ethylene / butene copolymer, EPR (ethylene-propylene copolymer), modified ethylene / butene copolymer, EEA (ethylene-ethyl acrylate copolymer), Modified EEA, modified EPR, modified EPDM (ethylene-propylene-diene terpolymer), ionomer, α-olefin copolymer, modified IR (isoprene rubber), modified SEBS (styrene-ethylene-butylene-styrene copolymer) ), A halogenated isobutylene-paramethylstyrene copolymer, an ethylene-acrylic acid modified product, an ethylene-vinyl acetate copolymer, an acid modified product thereof, and a mixture containing them as a main component. These may be used alone or in combination of two or more.

  Elastomers, especially those modified with acid anhydrides such as maleic anhydride, alkyl acrylate esters such as glycidyl methacrylate, epoxies and modified products thereof, are fine particles based on ethylene / vinyl alcohol copolymers. An alloy structure can be obtained, which is preferable.

  If the elastomer content in the EVOH composite resin used in the present invention is too small, the effect of improving the flexibility and durability due to the blending of the elastomer cannot be sufficiently obtained, and if it is too much, the gas barrier property is lowered. The content in the EVOH composite resin is preferably 10 to 40% by weight, more preferably 10 to 35% by weight, and particularly preferably 20 to 30% by weight. When the content of the elastomer in the EVOH composite resin is too large, the sea phase and the island phase are reversed in the sea-island structure described later, and the gas barrier property is remarkably lowered.

When a modified elastomer such as an acid-modified elastomer is used as the elastomer, an effect that less specific energy and a high kneading technique are not required at the time of kneading (dispersion) can be obtained. When the modified elastomer is used as the elastomer, the content of the modified elastomer in the EVOH composite resin is 20% by weight or less, for example, 5 to 20% by weight. %, Particularly 10 to 20% by weight.
In particular, in the present invention, it is preferable that 40 to 100% by weight of the elastomer in the EVOH composite resin is an acid-modified elastomer.

By the way, originally, ethylene / vinyl alcohol copolymer and various elastomers such as the above-mentioned ethylene elastomer are not compatible. In the present invention, the object of the present invention is achieved by forming a compatible state, that is, a good dispersion state in such an incompatible system. Therefore, in order to form this compatible state, it is important that at least a part of the elastomer is modified with maleic anhydride or the like, and the average acid value of the entire elastomer used to obtain a good dispersion form (acid modification ratio) of Ru der _1.5mg-CH 3 ONa / g or more.

The higher the acid value of the elastomer, the better the dispersion form, but the viscosity of the EVOH composite resin obtained with an increase in the acid value increases and the moldability is impaired. For this reason, in order to reduce the increase in viscosity due to the increase in the acid value, the acid value of the elastomer is preferably low in a range where a good dispersion state can be obtained, and the average acid value of the whole elastomer used is 7.5 mg. Ru der following -CH ₃ ONa / g.

In particular, by setting the average acid value of the elastomer to 2.0 to 5.0 mg-CH ₃ ONa / g, it is preferable because a product excellent in flexibility, gas barrier properties, durability, and moisture resistance can be obtained.

Moreover, even if the average acid value is the same, when the acid value of the modified elastomer contained in the elastomer to be used is high, the modified elastomer is mixed with the unmodified elastomer, thereby extruding even if the average acid value is lowered. Occasionally, gel-like foreign substances appear due to local overreaction. Therefore, the acid value of the modified elastomer to be used is preferably 15.0 mg-CH ₃ ONa / g or less.

That is, for example, an acid-modified elastomer having an acid value of 30 mg-CH ₃ ONa / g and an unmodified elastomer are mixed at a weight ratio of 17:83, and the average acid value of the entire elastomer is about 5 (= 30 × 17 ÷ 100). The mixed elastomer A and the mixed elastomer B in which an acid-modified elastomer having an acid value of 10 and an unmodified elastomer are mixed at a weight ratio of 50:50 and the average acid value of the entire elastomer is 5 are obtained by using this. Even if the apparent viscosity and the dispersed particle size of the EVOH composite resin are the same, the processing stability is greatly different. In the mixed elastomer A, gel-like foreign matters are scattered at the time of extrusion, but the mixed elastomer B has good stability. Obtainable. Therefore, the acid value of the modified elastomer used is preferably 15.0 mg-CH ₃ ONa / g or less. Incidentally, the acid value of the lower limit of the modified elastomer will be _{3mg-CH 3} ONa / g.

In particular, by setting the acid value of the acid-modified elastomer to be used to 3.0 to 8.0 mg-CH ₃ ONa / g, it is preferable because a product excellent in flexibility, gas barrier properties, durability, and moisture resistance can be obtained.

  Thus, by blending an elastomer with an ethylene / vinyl alcohol copolymer, flexibility and durability are improved, but a decrease in gas barrier properties is unavoidable. However, by taking a fine alloy structure of the ethylene / vinyl alcohol copolymer and the elastomer, in particular, the island phase of the elastomer is dispersed in the sea phase of the ethylene / vinyl alcohol copolymer. The structure in which the ethylene / vinyl alcohol copolymer is dispersed in the form of dots is preferable because it can suppress a decrease in gas barrier properties due to the blending of the elastomer.

  In particular, the amount of elastomer relative to the ethylene / vinyl alcohol copolymer (the sum of the ethylene / vinyl alcohol copolymer constituting the sea phase and the ethylene / vinyl alcohol copolymer phase present in the form of dots in the island phase of the elastomer) It is preferable that the proportion of the ethylene / vinyl alcohol copolymer phase existing in the form of scattered dots in the island phase (hereinafter, the ratio is referred to as “scattered dispersion”) is about 5 to 40% by weight. If this proportion is less than 5% by weight, the effect of having the ethylene / vinyl alcohol copolymer phase present in the form of scattered dots in the island phase of the elastomer cannot be obtained sufficiently, and conversely if it exceeds 40% by weight. Further, the ethylene / vinyl alcohol copolymer phase as the sea phase is too small, and the gas barrier property may be lowered.

  The size of the elastomeric island phase and the size of the ethylene / vinyl alcohol copolymer phase in the elastomeric island phase are about 0.4 to 1.5 μm in size of the elastomeric island phase. The size of the polymer phase is preferably about 0.05 to 0.5 μm.

  The EVOH composite resin used in the present invention may contain a resin component other than the ethylene / vinyl alcohol copolymer as a resin component. In that case, of the all resin components in the EVOH composite resin, 70% by weight or more is preferably an ethylene / vinyl alcohol copolymer for securing gas barrier properties.

  Examples of other resin components in this case include one or more of polyamide resins.

  Moreover, you may add additives, such as an anti-aging agent and an oxidative degradation agent, to the EVOH type composite resin used for this invention as needed.

  By the way, considering the processability of EVOH composite resin, especially the extrusion stability in a thin film, the fluidity of EVOH composite resin is important and measured at 250 ° C. under a load of 5005 g in accordance with ASTM D1238. The MFR value (hereinafter referred to as “MFR (250 ° C./5005 g)”) is preferably 3.0 or more. Although there is no restriction | limiting in particular about the upper limit of MFR (250 degreeC / 5005g) of this EVOH type composite resin, Usually, it is 20 or less.

The EVOH composite resin used in the present invention, in particular, the EVOH composite resin having a sea-island structure as described above can be produced by, for example, the following method (1) or (2).
(1) A method in which an ethylene / vinyl alcohol copolymer and an elastomer are kneaded at a predetermined blending ratio to form a master batch, and then the master batch and the ethylene / vinyl alcohol copolymer are kneaded.
(2) A method of melt kneading an ethylene / vinyl alcohol copolymer and an elastomer blend by high shear.

  Next, the polyester / polyether copolymer used in the present invention will be described.

  The polyester / polyether copolymer used in the present invention may be any as long as it is generally used for a laminated resin for a hose inner tube, and a commercially available product may be used, for example, “Toray DuPont” Hytrel 4047 "or the like can be used.

  The polyester / polyether copolymer may be used alone or in combination of two or more kinds of aromatic polyesters or polyalkylene glycols having different contents and the like.

  As described above, since the EVOH composite resin and the polyester / polyether copolymer have low adhesiveness, it is necessary to interpose an adhesive layer between the EVOH composite resin layer and the polyester / polyether copolymer layer. is there.

  The adhesive layer is preferably a layer containing a modified polyolefin resin as an adhesive resin. As the modified polyolefin resin, a commercially available product can be used, for example, “Modic-AP” manufactured by Mitsubishi Chemical Corporation.

  As the modified polyolefin resin, one kind may be used alone, or two or more kinds of polyolefin resins or unsaturated carboxylic acids or derivatives thereof used for modification may be mixed and used.

  If the thickness of such an adhesive layer is too thin, sufficient interlayer adhesion cannot be obtained, and if it is too thick, further effects cannot be expected and it is uneconomical, and the thickness of the resin tubular body increases. 3 to 20 μm is preferable.

  Next, the laminated resin tubular body for hose inner pipes of the present invention made of such a resin and the refrigerant transport hose of the present invention having this laminated resin tubular body for hose inner pipes will be described with reference to the drawings. In the following, the illustration of the adhesive layer between the EVOH composite resin layer and the polyester / polyether copolymer layer is omitted. The adhesive layer is not counted in the number of layers.

  FIGS. 1A to 1E are perspective views showing an embodiment of a laminated resin tubular body of the present invention, and FIGS. 2 and 3 are perspective views showing an embodiment of a refrigerant transport hose of the present invention. It is.

  A laminated resin tubular body 1A in FIG. 1A has a two-layer laminated structure in which a second resin layer 1b, an adhesive layer (not shown), and a first resin layer 1a are laminated in this order from the inside. Also, the laminated resin tubular body 1B of FIG. 1B is a two-layer laminate in which a first resin layer 1a, an adhesive layer (not shown), and a second resin layer 1b are laminated in this order from the inside. Structure.

  A laminated resin tubular body 1C in FIG. 1C includes, from the inside, a first resin layer 1a-1, an adhesive layer (not shown), a second resin layer 1b, an adhesive layer (not shown), a first The laminated resin tubular body 1D shown in FIG. 1 (d) has a first resin layer 1a-1 and an adhesive layer from the inside. (Not shown), second resin layer 1b-1, adhesive layer (not shown), first resin layer 1a-2, adhesive layer (not shown), second resin layer 1b-2, adhesive This is a five-layered laminated structure in which layers (not shown) and the first resin layer 1a-3 are laminated in this order. The laminated resin tubular body 1E of FIG. 1E is laminated from the inside in the order of the third resin layer 1c, the second resin layer 1b, the adhesive layer (not shown), and the first resin layer 1a. It has a three-layer structure.

  Here, the first resin layers 1a, 1a-1, 1a-2, and 1a-3 are layers mainly responsible for moisture resistance and flexibility, and are composed of the above-described polyester-polyether copolymer.

The film thickness of the first resin layers 1a, 1a-1, 1a-2, and 1a-3 is preferably thicker from the viewpoint of the moisture resistance of the hose. However, when the film thickness increases, the flexibility of the hose is sacrificed. To.
Therefore, the thickness of the first resin layer is preferably 10 to 400 μm, particularly 15 to 100 μm.

  The second resin layers 1b, 1b-1, and 1b-2 are layers mainly responsible for gas barrier properties, and are composed of the above-described EVOH composite resin. The film thickness of the second resin layers 1b, 1b-1, 1b-2 is preferably as thick as possible in terms of gas barrier properties and durability of the hose. At the expense of Therefore, the film thickness of the second resin layers 1b, 1b-1, 1b-2 is preferably 20 to 300 μm, particularly 50 to 100 μm.

  The third resin layer 1c in FIG. 1 (e) is a layer mainly responsible for durability and flexibility, and preferably includes polyamide 6:58 to 72 parts by weight and elastomer: 42 to 28 parts by weight (however, polyamide 6 and the total amount of the elastomer are 100 parts by weight.) Polyamide having a structure in which the island phase of the elastomer is dispersed in the sea phase of the polyamide 6 and the polyamide 6 is dispersed in the form of dots in the island phase of the elastomer. 6-Elastomer composite resin. Here, if the polyamide 6 of the polyamide 6-elastomer composite resin is less than 58 parts by weight, the gas barrier property is inferior even if the morphology of the specific sea-island structure is used. On the other hand, when the amount of polyamide 6 is more than 72 parts by weight, even if it is a morphology of the specific sea-island structure, the flexibility is inferior.

  Further, even when the polyamide 6-elastomer composite resin is in the composition range of the specific polyamide 6-elastomer, when the specific sea-island structure morphology is not exhibited, good gas barrier properties and flexibility can be obtained. Can not. In order to make this gas barrier property and flexibility both the best, especially for polyamide 6 (the total of polyamide 6 constituting the sea phase and the polyamide 6 phase existing in the form of scattered dots in the island phase of the elastomer). It is preferable that the ratio of the polyamide 6 phase existing in the form of dots in the island phase of the elastomer (hereinafter, the ratio is referred to as “spot-like dispersion ratio”) is about 2.5 to 30% by weight. If this proportion is less than 2.5% by weight, the above-mentioned effect due to the presence of the polyamide 6 phase in the form of scattered dots in the island phase of the elastomer cannot be sufficiently obtained. Conversely, if it exceeds 30% by weight, The polyamide 6 phase as the sea phase is too small and the gas barrier property may be lowered.

  The size of the elastomeric island phase and the size of the polyamide 6 phase in the elastomeric island phase are approximately 0.4 to 1.5 μm for the elastomeric island phase and 0.05 for the polyamide 6 phase. It is preferable that it is about -0.5 micrometer.

  As the elastomer, ethylene / butene copolymer, modified ethylene / butene copolymer, EEA (ethylene-ethyl acrylate copolymer), modified EEA, modified EPR (ethylene-propylene copolymer), modified EPDM (ethylene-propylene) -Diene terpolymer), ionomer, α-olefin copolymer, modified IR (isoprene rubber), modified SEBS (styrene-ethylene-butylene-styrene copolymer), halogenated isobutylene-paramethylstyrene copolymer , Ethylene-acrylic acid-modified products, ethylene-vinyl acetate copolymers, acid-modified products thereof, and mixtures containing these as main components. These may be used alone or in combination of two or more.

  You may add additives, such as anti-aging agent and an oxidative degradation agent, to this polyamide 6-elastomer type composite resin as needed.

In addition, as a method of forming the morphology of the specific sea-island structure of the polyamide 6-elastomer composite resin,
(1) A method in which polyamide 6 and elastomer are kneaded at a predetermined mixing ratio to form a master batch, and then the master batch and polyamide 6 are kneaded.
(2) A method of melt-kneading polyamide 6 and an elastomer blend by high shear.
Etc.

  In the laminated resin tubular body 1A having a two-layer structure shown in FIG. 1A, the thickness of the second resin layer 1b is set to 30 to 200 μm, and the thickness of the first resin layer 1a is set to 20 to 80 μm. Is preferred. Moreover, in the laminated resin tubular body 1B having a two-layer laminated structure shown in FIG. 1B, the thickness of the first resin layer 1a is 20 to 80 μm, and the thickness of the second resin layer 1b is 30 to 200 μm. It is preferable to do.

  In the laminated resin tubular body 1C having a three-layer laminated structure shown in FIG. 1 (c), the first resin layers 1a-1 and 1a-2 each have a thickness of 30 to 200 μm, and the second resin layer 1b has a thickness. It is preferable to set it as 20-80 micrometers. Further, in the laminated resin tubular body 1D having the five-layer laminated structure shown in FIG. 1D, the first resin layers 1a-1 and 1a-3 have a thickness of 20 to 100 μm, respectively, and the first resin layer 1a- 2 is preferably 20 to 100 μm, and the second resin layers 1b-1 and 1b-2 are preferably 20 to 80 μm in thickness.

  In the laminated resin tubular body 1E having a three-layer laminated structure shown in FIG. 1 (e), the first resin layer 1a has a thickness of 20 to 200 μm, the second resin layer 1b has a thickness of 20 to 50 μm, The thickness of the third resin layer 1c is preferably 150 to 250 μm.

  The laminated resin tubular body is a four-layer laminate of first resin layer / (adhesive layer) / second resin layer / (adhesive layer) / first resin layer / (adhesive layer) / second resin layer. It may be a structure.

  The laminated resin tubular bodies 1A to 1E having such a multi-layer structure can be easily manufactured by integral molding by co-extrusion molding of the plurality of resin layers. Since the polymer and the polyester / polyether copolymer have low adhesiveness, a modified polyolefin that forms the aforementioned adhesive layer between the EVOH composite resin layer and the polyester / polyether copolymer layer upon coextrusion. The resin is extruded and an adhesive layer is interposed. Since polyamide and EVOH composite resin are relatively excellent in adhesiveness, a special treatment for adhesion is separately performed between the above-described third resin layer 1c and second resin layer 1b during coextrusion. There is no need to do it.

  As described above, in the refrigerant transport hose, when moisture enters from the outside of the hose, the moisture content of the refrigerant as the internal fluid and the lubricating oil of the compressor increases, and the expansion valve freezes and the piping is clogged. Therefore, in the laminated resin tubular body for an inner tube of a hose of the present invention, it is preferable to laminate a polyester / polyether copolymer layer having high moisture resistance on the outer peripheral side of the EVOH composite resin layer. Furthermore, it is preferable to laminate a polyamide-based composite resin layer excellent in impulse resistance and refrigerant resistance on the inner peripheral side of the EVOH-based composite resin layer.

  In the refrigerant transport hose 10 of FIG. 2, the reinforcing yarn layer 3 is formed between the inner rubber layer 2 and the outer rubber 5, and the above-described laminated resin tube of the present invention is formed on the inner periphery of the inner rubber layer 2. A body 1 is formed. The reinforcing yarn layer 3 includes a first reinforcing yarn layer 3A in which the reinforcing yarn is wound in a spiral shape, and a second reinforcing yarn layer 3B in which the reinforcing yarn is wound in a spiral shape in a direction opposite to the first reinforcing yarn layer 3A. The intermediate rubber layer 4 is laminated. Note that an adhesive layer may be provided between the laminated resin tubular body 1 and the inner tube rubber layer 2 as necessary.

  The refrigerant transport hose 10A of FIG. 3 is the same as the refrigerant transport hose 10 of FIG. 2 except that the inner rubber layer 6 is further formed as the innermost layer on the inner layer of the laminated resin tubular body 1 of the present invention. An adhesive layer may be provided between the inner rubber layer 6 and the laminated resin tubular body 1 as necessary.

  There is no restriction | limiting in particular about the other structure of the refrigerant | coolant transport hose of this invention, The structure of the normal refrigerant | coolant transport hose is employable.

  For example, in the refrigerant transport hoses 10 and 10A shown in FIGS. 2 and 3, the rubber constituting the inner rubber layer 2 and the outer rubber 5 is generally butyl rubber (IIR), chlorinated butyl rubber (C1-IIR), chlorinated. Polyethylene, chlorosulfonated polyethylene, brominated butyl rubber (Br-IIR), isobutylene-bromoparamethylstyrene copolymer, EPR (ethylene-propylene copolymer), EPDM (ethylene-propylene-diene terpolymer), NBR (acrylonitrile butadiene rubber), CR (chloroprene rubber), hydrogenated NBR, acrylic rubber, ethylene acrylic rubber (AEM), a blend of two or more of these rubbers, or a polymer based on these rubbers Blends, preferably butyl rubber, EPDM rubber are used. That. These rubbers can be applied with compounding recipes such as commonly used fillers, processing aids, anti-aging agents, vulcanizing agents, and vulcanization accelerators.

  The rubber type of the inner rubber layer 2 and the rubber type of the jacket rubber 5 may be the same type or different types.

  Moreover, the rubber | gum of the intermediate | middle rubber layer 4 should just have the adhesiveness with the inner-layer rubber layer 2 and the jacket rubber 5, and there is no restriction | limiting in particular.

The reinforcing yarn is not particularly limited as long as it is usually used. In general, polyester, wholly aromatic polyester, nylon, vinylon, rayon, aramid, polyarylate, polyethylene naphthalate and blended yarns thereof are used.
The refrigerant transport hose of the present invention preferably has a reinforcing layer in which such reinforcing yarn is wound around the laminated resin tubular body for a hose inner tube in a spiral shape or a blade shape.

  The thickness of the inner rubber layer 2 is preferably about 0.8 to 4 mm from the viewpoint of flexibility. Furthermore, it is preferable that the thickness of the intermediate rubber layer 4 including the reinforcing yarn is about 0.5 to 5 mm, and the thickness of the outer rubber layer 5 is about 1 to 2 mm.

  In the refrigerant transport hose 10A shown in FIG. 3, the rubber constituting the inner rubber layer 6 includes IIR, chlorinated IIR, brominated IIR, CR, NBR, hydrogenated NBR, acrylic rubber, ethylene acrylic rubber, and the like. The thickness is preferably about 0.3 to 1.5 mm.

  Such a refrigerant transport hose of the present invention is manufactured by extruding and laminating the material of each constituent layer to a predetermined thickness on a mandrel and vulcanizing at 140 to 170 ° C. for 30 to 120 minutes according to a conventional method. can do.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

  The rubber ratios of the inner rubber layer, intermediate rubber layer, and outer rubber layer used in the following examples and comparative examples are as shown in Tables 1 to 3 below.

Moreover, the material used for manufacture of a laminated resin tubular body is as follows, and the compounding of each resin layer which comprises a resin tubular body is as Table 4 and Table 5 showing.
Hereinafter, the unit of the acid value “mg-CH ₃ ONa / g” is omitted.
In the EVOH composite resins of the resin layers II-1 to II-10, the island phase of the elastomer is dispersed in the sea phase of the ethylene / vinyl alcohol copolymer, and the ethylene / vinyl alcohol copolymer is further dispersed in the island phase of the elastomer. The polymer phase is present in the form of dots. Table 5 shows the dispersed particle size of the island phase of the elastomer, the average acid value of the entire elastomer component, and the MFR of the blend.

Polyamide 6: 6 nylon “1022B” manufactured by Ube Industries, Ltd.
Ethylene / vinyl alcohol copolymer: Kuraray "L-101B"
Maleic anhydride-modified EPR: “T-7761” manufactured by JSR Corporation
(Acid value _7.4mg-CH 3 ONa / g)
Polyamide / polyether copolymer: “XPA9044X2” manufactured by Ube Industries, Ltd.
α-Polyolefins: Mitsui Chemicals Co., Ltd. α-olefin polymers (both ethylene and butene)
Polymer) “Toughmer A-1050”
Modified α-polyolefin: Maleic acid-modified α-olefin polymer manufactured by Mitsui Chemicals, Inc.
(Ethylene / Butene Copolymer) “Toughmer MH7010”
EPR: JSR "EP961"
Modified EPR-1: “T7712” manufactured by JSR (acid value 0.9)
Modified EPR-2: “T7741” manufactured by JSR (acid value 4.7)
Modified EPR-3: “T7761” manufactured by JSR (acid value 7.4)
Modified EPR-4: “KA8962” manufactured by Bayer (acid value 18.5)
Polyester / polyether copolymer: “Hytrel 4047” manufactured by Toray DuPont
Modified polyolefin resin: “Modic-AP” manufactured by Mitsubishi Chemical Corporation

Examples 1-6 , Comparative Examples 1-7 , Reference Examples 1-9
<Manufacture of refrigerant transport hoses>
A refrigerant transport hose having the structure shown in FIG. 2 was manufactured using a resin tubular body having a laminated structure of 1 to 3 layers shown in Tables 6 and 7.

  A laminated resin tubular body 1 having a total film thickness of 300 μm was formed on a mandrel having a diameter of 13 mm in the laminated configuration shown in Tables 6 and 7, and then the inner layer rubber shown in Table 1 was extruded to a thickness of 1.6 mm. On top of this, 48 polyester reinforcing yarns of 10 times / 38 mm are drawn at 1100 dtex / 5 and wound into a spiral shape, and the intermediate rubber shown in Table 2 is extruded to a thickness of 0.3 mm on this reinforcing yarn layer. On top of that, 48 polyester reinforcing yarns with a number of times of 10 times / 38 mm at 1100 dtex / 5 were aligned and wound spirally in the opposite direction. Next, the jacket rubber shown in Table 3 was extruded to a thickness of 1.2 mm and vulcanized at 150 ° C. for 45 minutes to obtain a refrigerant transport hose having an inner diameter of 13 mm and an outer diameter of 21 mm.

<Evaluation>
The obtained refrigerant transport hose was examined for flexibility, Freon gas barrier properties, impulse resistance, moisture resistance, extrusion moldability, appearance during molding, and adhesiveness by the following methods. The results are shown in Tables 6 and 7. .

Flexibility:
It was measured by a three-point bending test.
The center was pushed at a load cell of 500 mm / min with a span of 200 mm between the rollers, the indentation load was measured, and the value was shown as an index when the value of Comparative Example 4 was set to 100. The smaller this value, the better the flexibility.

Freon gas barrier properties:
A predetermined amount of Freon gas was filled in the hose and left in a constant temperature bath at 90 ° C., and the weight decreased was measured every 24 hours. After the amount of weight loss per unit time was stabilized, the amount of leakage per 1 m / day of the hose was measured and indicated as an index when the amount of leakage in Comparative Example 4 was taken as 100. The lower this value, the better the gas barrier property.

Impulse resistance:
It investigated by the repeated pressurization test.
Under the conditions of 0 to 140 ° C., 0 to 3.3 MPa, and 20 CPM, the inner surface of the hose was repeatedly pressurized with PAG oil, and it was confirmed that the hose was cracked and the airtightness was ensured. The numerical values in the table are the number of repetitions (10,000 times) until the airtightness is impaired, and the larger the value, the better the impulse resistance.

Moisture resistance:
According to the following procedures 1 to 5, the moisture content of ethylene glycol was measured, and the moisture resistance of the hose was evaluated.
Procedure 1 Nitrogen gas (purity 99.996% or more) is passed through the hose to make it dry.
Procedure 2 Initial water of ethylene glycol (purity 99.5%, water content 1000ppm or less)
Measure the fraction. The moisture content measurement conforms to DIN 51 777.
Step 3 Fill the hose with ethylene glycol.
Procedure 4 Make the hose U-shaped and immerse it in the water tank.
Procedure 5 Set the water tank at 40 ° C, soak for 500 hours, and then ethylene glycol in the hose.
The moisture content of the water was measured and evaluated according to the following criteria.
Evaluation ◎ Moisture content less than 0.15% by weight
Evaluation ○ Moisture content 0.15 wt% or more and less than 0.25 wt%
Evaluation △ Moisture content 0.25 wt% or more and less than 0.45 wt%
Evaluation x Moisture content of 0.45% by weight or more

Extrudability:
Excellent (◎), which has no fluctuation in the discharge pressure during extrusion, no change in thickness in the longitudinal direction, and excellent in thin film moldability, and there is no fluctuation in the discharge pressure during extrusion, almost no fluctuation in thickness in the longitudinal direction. What is possible is good (○), thin film molding is possible, but what is slightly inferior in thickness variation in the longitudinal direction and circumferential direction (△), thin film molding is impossible Things were evaluated as inferior (x).

Appearance during molding:
Visually observe the appearance when extruding the resin layer, there is no foreign matter, fish eyes, etc., and excellent smoothness, excellent (◎), foreign matter, fish eyes, etc. are confirmed slightly, but smooth ones are good ( ○), foreign matters, fish eyes, etc., which were conspicuous and some were not smooth, were slightly inferior (Δ), and those that were not smooth at all were evaluated as no (×).

Adhesiveness:
In the above evaluation test, etc., those that do not peel off between the inner peripheral layer, the intermediate layer, and the outer peripheral layer are excellent (◎), those that hardly peel off between each layer are good (◯), and those that peel off from each layer are inferior ( (Triangle | delta) was evaluated as.

  According to Tables 6 and 7, according to the laminated resin tubular body for hose inner pipes, a layer made of a polyester / polyether copolymer is laminated on the inner peripheral side and / or outer peripheral side of the EVOH composite resin layer via an adhesive layer. For example, it can be seen that a refrigerant transport hose excellent in flexibility, gas barrier properties, durability and moisture resistance, as well as moldability, appearance, and interlayer adhesion can be obtained.

In particular, when the resin of the resin layers II-1 and II-2 is used for the EVOH composite resin layer, a refrigerant transport hose that is remarkably excellent in flexibility, gas barrier properties, durability, and moisture resistance can be obtained.
From this, it can be seen that there are suitable ranges for the average acid value of the EVOH composite resin used in the present invention and the acid value of the modified elastomer.
Further, it can be seen that the polyester / polyether copolymer layer is superior to the polyamide / polyether copolymer layer in improving moisture resistance.

It is a perspective view which shows embodiment of the laminated resin tubular body of this invention. It is a perspective view which shows embodiment of the hose for refrigerant | coolant transportation of this invention. It is a perspective view which shows other embodiment of the hose for refrigerant | coolant transport which concerns on this invention.

1, 1A, 1B, 1C, 1D, 1E Laminated resin tubular body 1a-1, 1a-2, 1a-3 First resin layer 1b, 1b-1, 1b-2 Second resin layer 1c Third resin Layer 2 Inner rubber layer 3 Reinforcement yarn layer 3A First reinforcement yarn layer 3B Second reinforcement yarn layer 4 Intermediate rubber layer 5 Outer rubber 6 Inner rubber layer 10, 10A Refrigerant transport hose

Claims (10)

A laminated resin tubular body for an inner tube of a hose provided with a layer made of an EVOH composite resin containing an ethylene / vinyl alcohol copolymer and an elastomer,
The average acid value of the entire said elastomer is _1.5~7.5mg-CH 3 ONa / g,
A polyamide-based composite resin layer containing polyamide and an ethylene-propylene copolymer is laminated on the inner peripheral side of the EVOH-based composite resin layer, and a layer made of a polyester / polyether copolymer is laminated on the outer peripheral side via an adhesive layer. A laminated resin tubular body for a hose inner tube.   The laminated resin tubular body for a hose inner pipe according to claim 1, wherein the elastomer content of the EVOH composite resin is 10 to 40% by weight.   3. The laminated resin tubular body for an inner tube of a hose according to claim 2, wherein the elastomer is a modified elastomer or a mixture of a modified elastomer and an unmodified elastomer.   The laminated resin tubular body for an inner tube of a hose according to any one of claims 1 to 3, wherein the modified elastomer content of the EVOH composite resin is 5 to 20% by weight. The laminated resin tubular body for an inner tube of a hose according to claim 3 or 4, wherein the acid value of the modified elastomer is ₃ to 15.0 mg-CH3ONa / g. In any one of claims 1 to 5, wherein the EVOH composite resin layer has a sea phase consisting of ethylene-vinyl alcohol copolymer, a sea-island structure having a dispersed phase consisting of an elastomer, the said elastomer A laminated resin tubular body for an inner tube of a hose, characterized in that an ethylene / vinyl alcohol copolymer is dispersed in a dotted pattern in an island phase. The laminated resin tubular body for an inner tube of a hose according to any one of claims 1 to 6 , wherein the ethylene / vinyl alcohol copolymer has an ethylene content of 28 to 40 mol%. The laminated resin tubular body for a hose inner pipe according to any one of claims 1 to 7 , wherein the adhesive layer contains a modified polyolefin resin. A refrigerant transport hose comprising the laminated resin tubular body for an inner tube of a hose according to any one of claims 1 to 8 . The refrigerant transport hose according to claim 9 , wherein a reinforcing layer made of a reinforcing yarn and an outer rubber layer are provided on an outer peripheral side of the laminated resin tubular body for an inner hose tube.

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