JP5041095B2 - Polyamide resin composition, method for producing the same, and refrigerant transport hose - Google Patents

Description

  The present invention relates to a polyamide resin composition suitable as a resin composition for forming a gas barrier layer of a refrigerant transport hose, a method for producing the same, and a refrigerant transport hose having a gas barrier layer made of the polyamide resin composition.

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

  From the viewpoint of improving ride comfort, rubber hoses with excellent vibration absorption performance are used in automotive air conditioner piping. The rubber hose has a gas barrier property in the innermost layer to prevent refrigerant leakage. A polyamide resin layer excellent in vibration durability such as impulse resistance is provided, an inner tube rubber layer is provided thereon, a reinforcing yarn layer made of organic fibers such as PET is provided thereon, and further thereon A structure in which an EPDM rubber layer having weather resistance is arranged is used (Japanese Patent Laid-Open No. 2007-15245).

  A refrigerant transport hose is also proposed in which a polyolefin-based elastomer is blended as a flexibility-imparting agent in the polyamide resin constituting the innermost gas barrier layer to impart refrigerant permeation resistance and flexibility (Japanese Patent Laid-Open No. 2000-120944). Issue gazette).

However, polyamide resins have a problem of deterioration due to refrigerants such as CFCs and oil from compressors, and this problem cannot be solved even by blending polyolefin elastomers. For this reason, conventional refrigerant transport hoses are durable. There are still issues to be addressed.
For example, when an acidic component is present even in a small amount in an air conditioner system, the polyamide resin composition may be significantly deteriorated by the acidic component under high temperature / high pressure actual use conditions and may not be able to be used. As this acidic component, an extreme pressure agent contained in compressor oil sealed together with the refrigerant can be considered. For this reason, depending on the type of oil used in the air conditioner and the environmental conditions, the conventional refrigerant transport hose may not be practically durable and may not be usable.

  In order to prevent the deterioration of the gas barrier layer made of such a polyamide resin composition due to refrigerant or compressor oil and to increase the durability of the refrigerant transport hose, the present applicant has first as a polyamide resin composition for gas barrier layer formation, The thing which mix | blended 1 type, or 2 or more types of metal compounds chosen from the group which consists of a hydroxide of a bivalent or trivalent metal, an oxide, and carbonate in a predetermined ratio was proposed (Japanese Patent Application No. 2009-077987). (Hereinafter referred to as “prior application”).

In the case of the polyamide resin composition of the prior application, by blending a specific metal compound in a predetermined ratio, deterioration due to the refrigerant or compressor oil of the gas barrier layer made of this polyamide resin composition can be effectively suppressed or prevented (hereinafter referred to as the following). The suppression or prevention is simply referred to as “prevention”), and the durability can be enhanced.
Although the details of the mechanism of the effect of preventing the deterioration of the polyamide resin composition by the refrigerant or compressor oil due to this specific metal compound are not clear, the metal compound blended in the polyamide resin composition is an acid acceptor, halogen acceptor, etc. It is presumed that the effect of preventing deterioration of the polyamide resin composition is manifested by the metal compound trapping deterioration factors such as acid components and halogen components contained in the refrigerant and oil.

  For this reason, the refrigerant transport hose of the prior application exhibits excellent durability performance without being affected by the oil used or the environment in the system used, and can be used stably and safely over a long period of time.

  Incidentally, as a method for producing a polyamide resin composition containing a flame retardant comprising a halogenated organic compound, Japanese Patent Publication No. 62-13380 discloses a low melting point polyamide master batch prepared by mixing a flame retardant with a low melting point polyamide in advance. And the method of mixing this low melting point polyamide masterbatch with high melting point polyamide is proposed. This method mixes a flame retardant with a high melting point polyamide as a master batch of a low melting point polyamide in order to prevent deterioration due to local overheating caused by a high shear force when the flame retardant is directly mixed with the high melting point polyamide. It does not suggest any method for mixing the above-mentioned specific metal compound into a polyamide resin composition containing a polyamide resin and a polyolefin-based elastomer.

JP 2007-15245 A JP 2000-120944 A Japanese Patent Application No. 2009-079487 Japanese Patent Publication No.62-13380

  In the case of the polyamide resin composition for gas barrier layer formation of the prior application, the deterioration of the gas barrier layer of the refrigerant transport hose by the refrigerant or compressor oil is prevented by blending a specific metal compound. In the polyamide resin composition containing a relatively large amount of the compound, due to the poor dispersibility of the metal compound with respect to the polyamide resin, when the gas barrier layer of the refrigerant transport hose is formed using this, the metal compound is poorly dispersed. The inhomogeneous phase portion became the starting point of fracture, and there was a problem that resin cracking occurred in a fatigue test such as a repeated pressurization test (impulse test) and sufficient performance could not be obtained. That is, the compounding of the metal compound prevents the polyamide resin composition from being deteriorated by the refrigerant or the compressor oil, and the durability problem caused by the deterioration due to the refrigerant or the compressor oil is improved. Due to poor dispersion, the state of the thin film surface layer (film skin) formed by extrusion molding of the polyamide resin composition was poor, and there was a problem that the impulse resistance was impaired.

The present invention solves this problem and provides a polyamide resin composition capable of effectively preventing deterioration due to refrigerant and compressor oil without impairing the impulse resistance without increasing the uniform dispersibility of the metal compound in the polyamide resin composition. The task is to do.
Another object of the present invention is to provide a refrigerant transport hose having a gas barrier layer made of the polyamide resin composition and having excellent durability performance.

The method for producing a polyamide resin composition according to the present invention (Claim 1) includes (a) a polyamide resin, (b) a polyolefin-based elastomer, (c) hydrotalcite, or a metal other than hydrotalcite and hydrotalcite. In the method for producing a polyamide resin composition comprising a metal compound comprising a compound, the metal compound other than the hydrotalcite is magnesium oxide, magnesium hydroxide, aluminum oxide, aluminum hydroxide, calcium oxide, calcium hydroxide, calcium carbonate. 1 or 2 or more types selected from the group consisting of zinc oxide, (c) obtained in a first kneading step of kneading a metal compound and (b) a polyolefin elastomer, and the first kneading step. And (a) a second kneading step for kneading the polyamide resin. And features.

The method for producing a polyamide resin composition according to claim 2 is characterized in that, in claim 1, the ratio of the metal compound (c) to the polymer component in the polyamide resin composition is 5 to 20% by weight .

Method for producing a polyamide resin composition 請 Motomeko 3 resides in that in Claim 1 or 2, the content of the polyolefin-based elastomer of the polyamide resin composition at 10 to 45% by weight relative to the total weight of the polyamide resin composition It is characterized by being.

According to a fourth aspect of the present invention, there is provided a method for producing a polyamide resin composition according to any one of the first to third aspects, wherein at least a part of the polyolefin-based elastomer is acid-modified.

The polyamide resin composition of the present invention (invention 5) is produced by the method of producing a polyamide resin composition according to claim 1 , and (c) metal for the polymer component in the polyamide resin composition. The ratio of the compound is 5 to 20% by weight, and the content of the polyolefin elastomer in the polyamide resin composition is 10 to 45% by weight with respect to the total weight of the polyamide resin composition .

The polyamide resin composition according to claim 6 is the polyamide resin composition for forming a gas barrier layer of the refrigerant transport hose according to claim 5 .

The refrigerant transport hose of the present invention (invention 7 ) is a refrigerant transport hose having a gas barrier layer made of a polyamide resin composition, wherein the polyamide resin composition is the polyamide resin composition according to claim 5. Features.

According to an eighth aspect of the present invention, there is provided the refrigerant transport hose according to the seventh aspect , wherein a reinforcing layer made of a reinforcing yarn and an outer rubber layer are provided on the outer peripheral side of the gas barrier layer.

  According to the method for producing a polyamide resin composition of the present invention, in producing a polyamide resin composition containing a polyamide resin, a polyolefin elastomer and a specific metal compound, the polyolefin elastomer and the metal compound are kneaded in advance. By kneading a polyamide resin into the kneaded product, the uniform dispersibility of the metal compound in the resin composition is improved, and the amount of the metal compound blended for improving the durability is increased, and the impulse resistance is ensured. be able to.

That is, the deterioration of the polyamide resin composition due to the refrigerant or the compressor oil is mainly due to the deterioration of the polyamide resin due to the acidic component in the refrigerant or the compressor oil. From this viewpoint, the metal compound is kneaded with the polyamide resin. It is considered effective to selectively disperse in the polyamide resin phase.
However, the polyamide resin has a poor uniform dispersibility of the metal compound. For example, when a large amount of a metal compound is kneaded with the polyamide resin, as described above, the uneven dispersibility of the metal compound results in an uneven unevenness of the film skin. A part is formed, and this part becomes a starting point of destruction and causes a decrease in impulse resistance.

  In contrast, polyolefin elastomers are excellent in uniform dispersibility of metal compounds, and by kneading a metal compound in advance with a polyolefin elastomer, the metal compound is uniformly dispersed in the resulting resin composition, thereby It is possible to prevent the occurrence of a defective part having a poor film skin.

  As described above, the deterioration of the polyamide resin composition due to the refrigerant transport hose is mainly due to the deterioration of the polyamide resin due to the acidic component, but the acidic component that deteriorates the polyamide resin composition is not limited to the polyamide resin phase alone. In some cases, it also penetrates into the polyolefin-based elastomer phase and passes through the polyolefin-based elastomer phase and then reaches the polyamide resin phase. The metal compound dispersed in the polyolefin-based elastomer phase has an acidic component that passes through this polyolefin-based elastomer phase. Capturing and effectively preventing deterioration of the polyamide resin.

  Therefore, in the polyamide resin composition obtained in the present invention, the metal compound is mainly dispersed in the polyolefin-based elastomer phase. In this way, the acidic component passing through the polyolefin-based elastomer phase is captured to capture the polyamide resin. In order to prevent the deterioration, a sufficient deterioration preventing effect by the metal compound can be obtained.

However, from the viewpoint of effectively exhibiting the above effects, in the present invention, the metal compound is preferably blended in a relatively large amount. Therefore, in the prior application, the content of the metal compound in the polyamide resin composition is a polymer. Although it is 1 to 15 weight% with respect to the sum total of a component and a metal compound, in this invention, the compounding quantity of a metal compound is more than in a prior application, (c) metal compound in a polyamide resin composition Is preferably 5 to 20% by weight based on the polymer component in the composition (claim 2).
In the present invention, even if a large amount of the metal compound is blended in this way, the metal compound is previously kneaded into the polyolefin-based elastomer having excellent dispersibility of the metal compound, so that poor dispersion of the metal compound does not become a problem.

  In the present invention, as the metal compound (c), hydrotalcite or a metal compound other than hydrotalcite and hydrotalcite is used (claim 1).

The content of the polyolefin-based elastomer of the polyamide resin composition to be 10 to 45 wt% blend, flexibility, preferred in terms of durability (claim 3).

The polyolefin elastomer may be at least partially acid-modified, thereby improving the compatibility with the polyamide resin (Claim 4 ).

The polyamide resin composition of the present invention is produced by such a method for producing the polyamide resin composition of the present invention, and is particularly suitable for forming a gas barrier layer of a refrigerant transport hose because of its excellent gas barrier properties and durability. It is suitable as a resin composition (Claims 5 and 6 ).

The refrigerant transport hose of the present invention has such a gas barrier layer made of the polyamide resin composition of the present invention, and there is almost no problem with deterioration of the gas barrier layer due to the refrigerant or compressor oil, and durability performance is improved. Excellent (claim 7 ).

The refrigerant transporting hose of the present invention, particularly the outer peripheral side of such a gas barrier layer, it is preferable that the reinforcing layer and the external rubber layer is provided consisting of reinforcing thread (Claim 8).

It is a perspective view which shows embodiment of the hose for refrigerant | coolant transportation of this invention.

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

[Polyamide resin composition and production method thereof]
First, the manufacturing method of the polyamide resin composition of this invention and the polyamide resin composition of this invention manufactured by this manufacturing method of a polyamide resin composition are demonstrated.

  The method for producing a polyamide resin composition of the present invention comprises (a) a polyamide resin, (b) a polyolefin-based elastomer, and (c) a divalent or trivalent metal hydroxide, oxide, and carbonate. In producing a polyamide resin composition containing one or more metal compounds selected from the following, first, (c) a metal compound and (b) a polyolefin-based elastomer are kneaded, and then the kneaded product obtained (A) A polyamide resin is kneaded.

<(A) Polyamide resin>
The polyamide resin used in the present invention is a polyamide resin mainly composed of amino acid, lactam or diamine and dicarboxylic acid. Specific examples of these components include lactams such as ε-caprolactam, enantolactam, ω-laurolactam, amino acids such as ε-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, tetramethylenediamine, hexa Methylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, m-xylylenediamine, p-xylylenediamine, 1 Diamines such as 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, bis-p-aminocyclohexylmethane, bis-p-aminocyclohexylpropane, isophoronediamine, adipic acid, suberic acid, azelaic acid, zebacic acid , Dodecanedioic acid, 1,4-cyclo Cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, dicarboxylic acids such as dimer acid. These constituent components are used for polymerization alone or in the form of a mixture of two or more, and the resulting poamide resin may be either a homopolymer or a copolymer.

  Polyamide resins (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polyhexamethylene sebamide (nylon 610) are particularly useful as the polyamide resin that is effectively used in the present invention. ), Polyundecanamide (nylon 11), polydodecanamide (nylon 12), polyhexamethylene adipamide / hexamethylene terephthalamide copolymer (nylon 66 / 6T), polycoupleramide / polyhexamethylene adipamide copolymer (Nylon 6/66) may be mentioned, and these may be used alone or in combination of two or more.

  The degree of polymerization of the polyamide is not particularly limited, and a 1% by weight sulfuric acid solution having a relative viscosity at 25 ° C. (hereinafter sometimes simply referred to as “relative viscosity”) in the range of 1.5 to 5.0. It can be used arbitrarily. In addition, in the polyamide resin, the terminal group concentration is adjusted by adding one or more of a monocarboxylic acid compound and / or a dicarboxylic acid compound or a monoamine compound and / or a diamine compound to the polyamide at an arbitrary stage. May be.

<(B) Polyolefin elastomer>
The polyamide resin composition of the present invention contains a polyolefin-based elastomer. By containing the polyolefin-based elastomer, flexibility and durability of the gas barrier layer composed of the polyamide resin composition can be imparted.

  Examples of the olefin elastomer include 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), halogenated isobutylene- Examples thereof include a 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.

  Polyolefin-based elastomers, especially those modified with acid anhydrides such as maleic anhydride, alkyl acrylate esters such as glycidyl methacrylate, epoxies, and modified products thereof, have a fine alloy structure based on polyamide resin. It can be obtained and is preferable.

  If the polyolefin elastomer content in the polyamide resin composition according to the present invention is too small, the effect of improving the flexibility and durability due to the blending of the polyolefin elastomer cannot be sufficiently obtained, and if too large, the gas barrier property Therefore, the content in the polyamide resin composition is preferably 10 to 45% by weight, particularly preferably 20 to 40% by weight. If the content of the polyolefin-based elastomer in the polyamide resin composition 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 polyolefin-based elastomer, an effect that less specific energy and a high kneading technique are not required at the time of kneading (dispersing) can be obtained. In the case of using a modified elastomer as the polyolefin-based elastomer, the content of the modified elastomer in the polyamide resin composition is 20% by weight or less, for example, It is preferable to set it as 5 to 20 weight%.
In particular, in the present invention, it is preferable that 40 to 100% by weight of the polyolefin elastomer in the polyamide resin composition is an acid-modified elastomer.

In order to make the polyamide resin composition and the polyolefin elastomer compatible with each other, that is, in a good dispersion state, it is preferable that at least a part of the elastomer is modified with maleic anhydride or the like to obtain a good dispersion form. Therefore, it is preferable that the average acid value (acid modification rate) of the whole elastomer used is 0.8 mg-CH ₃ ONa / g or more.

The higher the acid value of the elastomer, the better the dispersion form, but the viscosity of the polyamide resin composition obtained with an increase in the acid value increases and the molding processability 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. is preferably not more than -CH ₃ ONa / g.

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.

  Thus, by blending the polyolefin-based elastomer with the polyamide resin composition, the flexibility and durability are improved, but the gas barrier property is inevitably lowered. However, by adopting a fine alloy structure of polyamide resin and elastomer, the island phase of the elastomer is dispersed in the sea phase of the polyamide resin, and the polyamide resin is dispersed in the form of dots in the island phase of the elastomer. With such a structure, a decrease in gas barrier properties due to the blending of the elastomer can be suppressed, which is preferable.

  In particular, the ratio of the polyamide resin phase that is scattered in the island phase of the elastomer to the polyamide resin (the total of the polyamide resin that constitutes the sea phase and the polyamide resin phase that is scattered in the island phase of the elastomer) (Hereinafter, the ratio is referred to as “spot dispersion”) is preferably about 5 to 40% by weight. If this proportion is less than 5% by weight, it is not possible to sufficiently obtain the effect of the presence of the polyamide resin phase in the form of scattered dots in the island phase of the elastomer. There is a possibility that the polyamide resin phase becomes too small and the gas barrier property is lowered.

  The size of the elastomeric island phase and the size of the polyamide resin phase in the elastomeric island phase are approximately 0.1 to 3.0 μm for the elastomeric island phase and 0.5 for the polyamide resin phase. It is preferable that it is about -2.0 micrometers.

<(C) Metal compound>
The metal compound contained in the polyamide resin composition of the present invention is selected from divalent or trivalent metal hydroxides, oxides, and carbonates.
Here, examples of the divalent or trivalent metal include divalent metals such as magnesium, iron, zinc, calcium, nickel, cobalt, and copper, and trivalent metals such as aluminum, iron, and manganese.
Specific examples of hydroxides, oxides and carbonates of these metals include hydrotalcite, magnesium oxide, magnesium hydroxide, aluminum hydroxide, calcium oxide, and calcium carbonate. Hydrotalcite is preferred because it is considered to have an acid accepting effect.
These metal compounds may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. For example, hydrotalcite and a metal compound other than hydrotalcite may be used in combination. In that case, the use ratio of the hydrotalcite and the metal compound other than hydrotalcite is preferably hydrotalcite: metal compound other than hydrotalcite = 80: 20 to 50:50 by weight ratio. As the metal compound other than the site, magnesium oxide is particularly preferable.

Hydrotalcite is a kind of naturally occurring viscous mineral, and is a double hydroxide represented by the following general formula (I).
M ¹ _8-x M ² _x (OH) ₁₆ CO ₂ .nH ₂ O (I)

In formula (I), M ¹ is Mg ²⁺ , Fe ²⁺ , Zn ²⁺ , Ca ²⁺ , Li ²⁺ , Ni ²⁺ , Co ²⁺ , Cu ^2+, etc., M ² is Al ³⁺ , Fe ³⁺ , Mn ^3+, etc. ≦ x ≦ 2 and n ≧ 0.

As hydrotalcite, in the form containing crystal water, for example, Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ .3.5H ₂ O, Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ , Mg ₄ Al ₂ (OH) ₁₂ CO ₃ .3.5H ₂ O, Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, Mg ₅ Al ₂ (OH) ₁₄ CO ₃ .4H ₂ O, Mg ₃ Al ₂ (OH) ₁₀ CO _{3 · 1.7H 2 O, Mg 3 ZnAl} 2 (OH) 12 CO 3 · wH 2 O, Mg 3 ZnAl 2 (OH) 12 CO 3 and the like. Examples of commercially available hydrous hydrotalcite include “DHT-4A” and “DHT-6” manufactured by Kyowa Chemical Industry Co., Ltd.

  If the content of the metal compound in the polyamide resin composition is too small, the deterioration prevention effect due to the compounding of the metal compound cannot be sufficiently obtained, and if it is too much, an effect commensurate with the compounding amount cannot be obtained. As a result, the properties such as gas barrier properties, flexibility, and aging resistance are impaired. Therefore, the content of the metal compound in the polyamide resin composition is preferably 5 to 20% by weight, more preferably 5 to 15% by weight, based on the polymer component in the polyamide resin composition. Thus, it is preferable to blend a relatively large amount of the metal compound in order to obtain a sufficient effect of preventing deterioration due to the metal compound and to ensure durability, and according to the present invention, such a large amount of the metal compound is added. Even when a metal compound is blended, excellent impulse resistance performance can be obtained. However, if this compounding amount is excessively large, even if the kneading method of the present invention is adopted, the film surface may be deteriorated when the resin composition is extruded due to non-uniform dispersion of the metal compound. The blending amount is preferably not more than the above upper limit.

  Here, the polymer component in the polyamide resin composition refers to the total of polymer components such as (a) polyamide resin, (b) polyolefin-based elastomer, and other resins to be blended as necessary. .

<Other ingredients>
The polyamide resin composition of the present invention may contain a resin component other than the polyamide resin as a resin component. In that case, 70% by weight or more of the total polymer component in the refrigerant transport hose is a polyamide resin. It is preferable to ensure gas barrier properties.

  Examples of other resin components in this case include ethylene / vinyl alcohol resin.

  Further, the polyamide resin composition of the present invention includes other additives, that is, a lubricant, an antistatic agent, an anti-aging agent, an antioxidant, a coloring agent, a crystal nucleating agent, a filler, a reinforcing material, a heat resistance agent, and a light resistance agent. Etc. can also be added.

<Manufacturing method of polyamide resin composition>
As described above, in the present invention, in the production of the polyamide resin composition, (b) a polyolefin-based elastomer and (c) a metal compound are first kneaded, and (a) the polyamide resin is kneaded into the obtained kneaded product. To perform a two-stage kneading to make a polymer alloy.

The heating temperature condition in the kneading step of the polyolefin-based elastomer and the metal compound is preferably set low so that the fluidity of the elastomer can be obtained in order to prevent thermal degradation of the elastomer, depending on the type of polyolefin-based elastomer used For example, in the case of Toughmer A-1050S used in the examples described later, the temperature may be about 150 to 230 ° C.
In the present invention, as described later, since it is preferable to knead the polyamide resin subsequent to the kneading of the polyolefin-based elastomer and the metal compound, the temperature is such that there is no problem of thermal degradation of the elastomer and fluidity is obtained. It is preferable to heat and knead the mixture at a temperature equal to or higher than the melting point of the polyamide resin to be used, for example, about 10 to 60 ° C. higher than the melting point of the polyamide resin (first kneading step).
This kneading is not particularly limited as long as the metal compound is sufficiently uniformly dispersed in the polyolefin-based elastomer, and the kneading time and the like are not particularly limited.

  Next, a polyamide resin is added and kneaded to the kneaded product obtained by kneading the polyolefin elastomer and the metal compound (second kneading step). This kneading can be performed under the same conditions as in the first kneading step.

  In the present invention, in the first kneading step, only a part of the polyolefin-based elastomer used for producing the composition can be kneaded, and the remaining part can be kneaded in the second kneading step. From the viewpoint of uniform dispersibility, in the first kneading step, it is preferable to knead 70% by weight or more, preferably the entire amount, of the polyolefin elastomer used with the metal compound. For the same reason, it is preferable not to add the polyamide resin in the first kneading step, but to add and knead the whole amount of the polyamide resin used for producing the composition in the second kneading step.

  When blending the above-described other components blended as necessary into the polyamide resin composition, these components may be added and kneaded in the first kneading step or added and kneaded in the second kneading step. But you can.

  It is also possible to knead a polyolefin elastomer and a metal compound in advance to make a master batch and knead the polyamide resin to this master batch. However, the polyamide resin is added following the kneading of the polyolefin elastomer and the metal compound. It is efficient to knead.

[Hose for refrigerant transport]
Next, the refrigerant transport hose of the present invention using the polyamide resin composition of the present invention produced by the production method of the present invention as a constituent material of the gas barrier layer will be described with reference to the drawings.

  FIG. 1 is a perspective view for explaining a layer structure of a refrigerant transport hose 1 according to an embodiment. The innermost layer of the refrigerant transport hose 1 is composed of the gas barrier layer 2 made of the above-described polyamide resin composition of the present invention, and an inner rubber layer 3 is formed on the outer periphery thereof. Hereinafter, the first reinforcing yarn layer 4 is sequentially formed. The intermediate rubber layer 5, the second reinforcing yarn layer 6, and the outer rubber layer 7 are formed. The inner diameter of the hose 1 is usually about 6 to 20 mm, particularly about 8 to 19 mm.

  Hereinafter, the material of each layer will be described.

<Gas barrier layer>
The gas barrier layer 2 is made of the polyamide resin composition of the present invention.

The thickness of the gas barrier layer 1 made of such a polyamide resin composition is preferably thicker from the viewpoint of gas barrier properties. However, as the film thickness increases, the flexibility as a hose decreases.
Therefore, the film thickness of the gas barrier layer 2 is preferably 50 to 400 μm, particularly preferably 100 to 300 μm.

  In the refrigerant transport hose of the present invention, in the refrigerant transport hose 10 of FIG. 1, an inner rubber layer may be further formed as an innermost layer on the inner layer of the gas barrier layer 2.

  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 as follows.

<Inner rubber layer 3, outer rubber layer 7 and intermediate rubber layer 5>
As the rubber constituting the inner rubber layer 3 and the outer rubber layer 7, 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 blend with a polymer based on these rubbers, preferably butyl rubber or EPDM rubber. . 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 3 and the rubber type of the jacket rubber layer 7 may be the same or different.

  Moreover, the rubber | gum of the intermediate | middle rubber layer 5 should just have the adhesiveness with the inner-layer rubber layer 2 and the jacket rubber layer 7, and there is no restriction | limiting in particular.

  The thickness of the inner rubber layer 3 is preferably about 0.5 to 4 mm from the viewpoint of flexibility. The thickness of the intermediate rubber layer 5 is preferably about 0.1 to 0.6 mm, and the thickness of the outer rubber layer 7 is preferably about 0.5 to 2 mm.

<Reinforcing thread layers 4, 6>
The first reinforcing yarn layer 4 is obtained by winding a reinforcing yarn in a spiral shape, and the second reinforcing yarn layer 6 is obtained by winding a reinforcing yarn in a spiral shape in the opposite direction to the first reinforcing yarn layer 4. is there.

  The material of 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.

<Method for manufacturing refrigerant transport hose>
Such a refrigerant transport hose according to the present invention is formed by extruding the material of the gas barrier layer 2 and the inner rubber layer 3 to a predetermined thickness on a mandrel and laminating them on the mandrel, and winding the reinforcing yarn layer 4 on the intermediate rubber layer. 5 is extruded and laminated, the reinforcing yarn layer 6 is wound, then the outer rubber layer 7 is extruded and laminated, and then vulcanized at 140 to 170 ° C. for 30 to 120 minutes.

  Hereinafter, the present invention will be described more specifically with reference to Examples, Reference Examples and Comparative Examples.

[Examples 1 to 9, Reference Examples 1 to 3, Comparative Examples 1 to 7]
Each material was kneaded with the formulation shown in Tables 4 and 5 to produce a polyamide resin composition.
In the kneading, a twin-screw kneader manufactured by Toyo Seiki Co., Ltd. was used, and kneading was performed at 230 ° C., which is a temperature higher than the melting point (220 ° C.) of the polyamide resin. The kneading is performed in two stages, and the elastomer and hydrotalcite are kneaded in the first stage, and the elastomer and polyamide resin kneaded in the second stage are kneaded (two-stage kneading A: Examples 1 to 9, Reference examples 1 to 3).

  For comparison, a hydrotalcite-free additive (Comparative Example 1), a polyamide resin and an elastomer previously kneaded into a polymer alloy and then hydrotalcite added and kneaded (post-addition: Comparative Example 2), and The polyamide resin composition was produced in the same manner for the polyamide resin and hydrotalcite kneaded in advance after the polyamide resin and the elastomer were kneaded in advance (two-stage kneading B: Comparative Examples 3 to 7). .

  The materials used for the production of the polyamide resin composition are as follows.

Polyamide resin: 6 nylon “1022B” manufactured by Ube Industries, Ltd.
Elastomer: Mitsui Chemicals Co., Ltd. α-olefin polymer (ethylene butene copolymer) “Tuffmer A-1050S”
Maleic acid-modified elastomer: maleic acid-modified α-olefin polymer (ethylene / butene copolymer) “Tuffmer MH7010” manufactured by Mitsui Chemicals, Inc.
Hydrotalcite: “Hydrotalcite DHT-4A” manufactured by Kyowa Chemical Co., Ltd.
Composition formula: Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ .3.5H ₂ O
Magnesium oxide: “Kyowa Mug 30” manufactured by Kyowa Chemical Co., Ltd.
Composition formula: MgO
Zinc oxide: Sakai Chemical Industry Co., Ltd. (Zinc oxide 1 type)

  About the test piece which consists of an obtained polyamide resin composition, the characteristic evaluation was performed by the following method and the result was shown in Table 4,5.

<Strong retention after aging>
Using a tensile tester manufactured by Toyo Seiki Co., Ltd., for each test piece before and after the following aging test, the tensile strength was measured by stretching at a pulling speed of 50 mm / min, and the percentage after the aging test with respect to the value before the aging test Indicated.

<Elongation at break after aging>
Using a tensile tester manufactured by Toyo Seiki Co., Ltd., the test piece before and after the following aging test was stretched at a tensile rate of 50 mm / min to measure the elongation at break, and the percentage of the value after the aging test relative to the value before the aging test. Indicated.

(Aging test)
The following procedures 1 to 6 were performed.
1 Put 1 cc of water and 100 cc of polyalkylene glycol in a pressure vessel.
2 Put a test piece of width 10 × length 50 mm × thickness 0.1 mm.
3. After freezing the pressure vessel for 15 minutes, vacuum the pressure vessel for 5 minutes.
4 Add 100 cc of R-134a as the refrigerant.
5 Leave in a high temperature bath at 150 ° C for 4 weeks.
6 Remove the specimen from the container and use it for evaluation measurement.

<Surface roughness>
The center line average roughness was measured according to JIS B0601 using a “surface roughness measuring device Surfcorder SE-2300” manufactured by Kosaka Laboratory.

Moreover, the refrigerant | coolant transport hose shown in FIG. 1 was manufactured with the following method using each polyamide resin composition.
After the polyamide resin composition was extruded onto a mandrel having a diameter of 11 mm to form a gas barrier layer 2 having a thickness of 200 μm, the inner rubber layer was extruded to a thickness of 1.60 mm to form an inner rubber layer 3. On top of this, 22 polyester reinforcing yarns having a number of times of 10/10 cm are drawn at 1100 dtex / 4 and wound in a spiral shape, and the intermediate rubber layer 5 is extruded on the first reinforcing yarn layer 4 to a thickness of 0.30 mm. Furthermore, 22 polyester reinforcing yarns having a number of times of 10 times / 10 cm were drawn together at 1100 dtex / 4, and the second reinforcing yarn layer 6 was formed by spirally winding in the opposite direction to the above. Next, the outer rubber was extruded to a thickness of 1.2 mm to form the outer rubber layer 7 and vulcanized at 150 ° C. for 45 minutes to obtain a refrigerant transport hose having an inner diameter of 11 mm and an outer diameter of 19 mm.

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

  The resulting refrigerant transport hose was examined for impulse resistance by the following method, and the results are shown in Tables 4 and 5.

<Impulse resistance>
It investigated by the following 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 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.

Moreover, the external appearance of the gas barrier layer formed by extrusion of the polyamide resin composition at the time of manufacturing the refrigerant transport hose was visually observed and evaluated according to the following criteria, and the results are also shown in Tables 4 and 5.
(Evaluation criteria)
○: Film skin is good.
Δ: Slightly inferior film skin
×: film skin defect

  From Tables 4 and 5, a polyamide resin composition in which a metal compound is kneaded in advance with a polyolefin-based elastomer and then a polyamide resin is kneaded, particularly a polyamide resin composition in which the compounding amount of the metal compound is within a predetermined range is used as a gas barrier. It can be seen that the refrigerant transport hose of the present invention used for the layer is excellent in durability and impulse resistance.

  In Reference Example 3, hydrotalcite is not blended. Although this reference example 3 is a little inferior in aging resistance compared with Example 2 which mix | blended hydrotalcite, compared with the comparative example 4 which employ | adopted the kneading | mixing means B, impulse resistance, surface roughness, and extrusion appearance Is excellent. In Examples 5 and 6, hydrotalcite and magnesium oxide or zinc oxide are blended as a metal compound. Example 6 containing magnesium oxide is superior to Example 5 containing zinc oxide in breaking elongation and surface roughness. In Examples 8 and 9, the amount is set to the lower limit value and the upper limit value in the range of the elastomer content of 10 to 45% by weight. Comparing Examples 7 to 9 and Comparative Examples 5 to 7 having the same composition and different only kneading methods, it can be seen that the kneading means A is more effective than the kneading means B.

DESCRIPTION OF SYMBOLS 1 Refrigerant transport hose 2 Gas barrier layer 3 Inner rubber layer 4,6 Reinforcing thread layer 5 Intermediate rubber layer 7 Outer rubber layer

Claims (8)

In a method for producing a polyamide resin composition comprising (a) a polyamide resin, (b) a polyolefin-based elastomer, and (c) hydrotalcite, or a metal compound composed of a metal compound other than hydrotalcite and hydrotalcite. ,
The metal compound other than the hydrotalcite is one or more selected from the group consisting of magnesium oxide, magnesium hydroxide, aluminum oxide, aluminum hydroxide, calcium oxide, calcium hydroxide, calcium carbonate, and zinc oxide. Yes,
(C) a first kneading step of kneading the metal compound and (b) a polyolefin-based elastomer;
A method for producing a polyamide resin composition, comprising: a kneaded product obtained in the first kneading step; and (a) a second kneading step of kneading the polyamide resin.   The method for producing a polyamide resin composition according to claim 1, wherein the ratio of the metal compound (c) to the polymer component in the polyamide resin composition is 5 to 20% by weight.   The method for producing a polyamide resin composition according to claim 1 or 2, wherein the content of the polyolefin-based elastomer in the polyamide resin composition is 10 to 45% by weight with respect to the total weight of the polyamide resin composition.   The method for producing a polyamide resin composition according to any one of claims 1 to 3, wherein at least a part of the polyolefin elastomer is acid-modified. A polyamide resin composition produced by the method for producing a polyamide resin composition according to claim 1 ,
The ratio of the metal compound (c) to the polymer component in the polyamide resin composition is 5 to 20% by weight,
A polyamide resin composition, wherein the content of the polyolefin-based elastomer in the polyamide resin composition is 10 to 45% by weight based on the total weight of the polyamide resin composition.   6. The polyamide resin composition according to claim 5, which is a polyamide resin composition for forming a gas barrier layer of a refrigerant transport hose.   A refrigerant transport hose having a gas barrier layer made of a polyamide resin composition, wherein the polyamide resin composition is the polyamide resin composition according to claim 5.   8. The refrigerant transport hose according to claim 7, wherein a reinforcing layer made of a reinforcing yarn and an outer rubber layer are provided on an outer peripheral side of the gas barrier layer.

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