JPH02217683A - Tubing of resin in polyamide type - Google Patents

Abstract

PURPOSE:To lessen permeability for fron gas by forming a tubing from polyamide resin, and composing it of an inner layer made of polyamide resin etc. containing metaxyliren radicals and an outer layer made of specific metamorphosed elastomers. CONSTITUTION:An extruder is connected with each of a pair of tube dies arranged concentrically, and polyamide resin tubing consisting of an inner and an outer layer in different composition is molded by means of co-extrusion process. The inner layer is made of polyamide resin containing metaxyliren radicals or its copolymer with other materials. The outer layer is made of metamorphosed polyester elastomer obtained by putting monomers of unsaturated carbonic acid and its derivative in reaction with polyester elastomer.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a polyamide resin tubular body having low permeability to fluorocarbon gas, excellent oil resistance and heat resistance, and flexibility, particularly for use in automobile air conditioners. The present invention also relates to a polyamide resin tubular body having the above-mentioned excellent properties, which is ideal for tubes for fluorocarbon gas, which is a medium for electric refrigerators, and tubes for automobile fuel and clutch oil.

(Prior Art) Polyamide resins generally have excellent chemical resistance and oil resistance. In particular, it is characterized by extremely low permeability to fluorocarbon gas and gasoline. Therefore, it is used in applications that require particularly high reliability, such as high-pressure hose tubes, phenyl tubes for automobiles, and air brake piping tubes.

However, polyamide resin is difficult to process and assemble due to its lack of flexibility. In order to facilitate these operations, attempts have been made to add plasticizers to polyamide resins to give them flexibility. However, when used for a long time under high temperature conditions, the plasticizer flows out and flexibility is lost. Furthermore, various polyamide resins including nylon 12 and polyamide elastomers are very expensive compared to other engineering plastics. Therefore, for example, rubber materials such as nitrile rubber, which is highly flexible and relatively resistant to fluorocarbon gas, are used as tubes for fluorocarbon gas in car air conditioners.

Incidentally, recently, the use of fluorocarbon gas, which destroys the ozone layer, is being regulated from the standpoint of environmental protection.

In particular, Freon 12 (CCI2F2) has a large effect on the ozone layer, so its vapor pressure is higher than that of Freon 12, and Freon 22 (CHClF2) has less impact on the ozone layer.
2) is now being used. However, it became clear that the nitrile rubber mentioned above was swollen by Freon 22 and could not be used. Commonly used aliphatic polyamide resins (nylon 6, nylon 6 6, nylon 1
2) also have poor barrier properties against Freon 22.

As described above, a tubular body made of a resin that is stable against Freon 22, has barrier properties, has excellent chemical resistance, heat resistance, and oil resistance, and is flexible enough to be easily processed has not been obtained. is the current situation.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and its purpose is to provide a material with extremely low permeability to fluorocarbon gas, chemical resistance, heat resistance, and oil and oil resistance. It is an object of the present invention to provide a tubular body made of a resin that has excellent flexibility and is easy to process. Another object of the present invention is to provide a polyamide resin tubular body having the above-mentioned properties, which is ideal for refrigerant tubes in electric refrigerators, fuel tubes for automobiles, or brake oil tubes.

(Means for Solving the Problems) The polyamide resin tubular body of the present invention has an inner layer containing a metaxylylene group-containing polyamide resin or a metaxylylene group-containing polyamide resin and other polymer, and an outer layer containing an unsaturated carboxylic acid and its derivatives. It includes a modified polyester elastomer obtained by reacting a monomer selected from the following with a polyester elastomer.

The metaxylylene group-containing polyamide resin contained in the inner layer of the polyamide resin tubular body of the present invention is composed of xylylene diamine containing metaxylylene diamine as a main component and α,ω-aliphatic dicarboxylic acid having 4 to 10 carbon atoms. refers to a polymer containing 70 mol% or more of structural units produced from . The above-mentioned xylylene diamine whose main component is metaxylylene diamine refers to metaxylylene diamine or a mixture of metaxylylene diamine and para-xylylene diamine, and the content of para-xylylene diamine in the mixture is 30%. It is less than mol%.

Such metaxylylene group-containing polyamide resins include homopolymers obtained from metaxylylene diamine and the above aliphatic dicarboxylic acid, copolymers obtained from metaxylylene diamine and baraxylylene, and the above aliphatic dicarboxylic acid, and There are copolymers in which other monomers are copolymerized in addition to the constituent components of the above polymers. Homopolymers obtained from the metaxylylene diamine and aliphatic dicarboxylic acid include polymethaxylylene adipamide, polymethaxylylene adipamide, polymethaxylylene adipamide, and the like. Copolymers obtained from the metaxylylene diamine and paraxylylene diamine and aliphatic dicarboxylic acids include metaxylylene-valaxylylene adipamide copolymer, metaxylylene-paraxylylene biperamide copolymer, Examples include metaxylylene-paraxylylene azelamide copolymer. The monomer components contained in the copolymer copolymerized with the above-mentioned monomers include aliphatic diamines such as hexamethylene diamine, alicyclic diamines such as piperazine, and para-bis-(2-amino Aromatic diamines such as (ethyl)benzene, aromatic dicarboxylic acids such as terephthalic acid, lactams such as ε-caprolactam, and ω- such as T-aminohbutanoic acid.
These include aminocarboxylic acids and aromatic aminocarboxylic acids such as para-aminomethylbenzoic acid.

In the present invention, the meta-xylylene group-containing polyamide resin (hereinafter referred to as MXD-6) is preferably a polymer having an amino group at the molecular end, and the content of the amino group is 3.5 Xl0-5 equivalent. /g or more of the polymer is suitable. The upper limit of the amino group content is not particularly limited, and for example, a polymer in which all molecular terminals are amino groups may also be used.

If the content of amino groups at the molecular terminals is less than the above value, the interlayer adhesive strength with the modified polyester elastomer described below will not be sufficient, and the resulting tubular body will have insufficient tensile strength and impact resistance. MXD-6 having an amino group at the end of the molecule can be easily prepared by appropriately adding diamines such as hexamethylene diamine as a chain transfer agent during the preparation of MXD-6.

MXD-6 further has a relative viscosity of 1.5 or more, preferably 2.0 to 4.0. When the relative viscosity is less than 1.5, it becomes amorphous and becomes brittle.

The inner layer of the tubular body of the present invention may contain other polymers in addition to the above-mentioned MXD-6, including the following polymers: ■ Ethylene, α-olefin having 3 or more carbon atoms , and if necessary, other double bond-containing monomers, using a compound having a functional group that can react with an amino group (a monomer selected from unsaturated carboxylic acids and derivatives thereof). Modified polyolefin copolymer obtained by reacting a block copolymer composed of a vinyl aromatic compound and an olefin compound with an unsaturated carboxylic acid or its derivative or a modified block/graft copolymer obtained by reacting the block copolymer, the radically decomposable polymer, and the unsaturated carboxylic acid or its derivative.

Examples of α-olefins that can constitute the polyolefin copolymer used to prepare the modified polyolefin copolymer of (1) above include propylene, butene-1, hexene-1, decene-1,4-methylbutene-1,4 -Methylpentene-1 and the like. Other unsaturated compounds having a double bond include 5-ethylidene-2-
norbornene, 5-methylene-2-norbornene,
5-(2'-butenyl)-2-norbornene, 5-
Examples include (1°-propenyl)-2-norbornene, 5-hexymonyl-2-norbornene, 5-ethyl-2,5-norbornadiene, and dicyclopentadiene.

Among the compounds (modifiers) having a functional group capable of reacting with the above amino group, unsaturated carboxylic acids include acrylic acid,
Methacrylic acid, α-ethyl acrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, crotonic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, cis-4-cyclohexane-1,2-dicarboxylic acid, endo-bicyclo( 2,2,1,) hept-5-ene-2,3
-Dicarboxylic acid (nadic acid), methyl endosys-
Bicyclo(2,2,1,)hept-5-ene-2,3-
Examples include dicarboxylic acids and methylnadic acid. Examples of derivatives of unsaturated carboxylic acids include derivatives of the above acids, such as acid halides, amides, imides, acid anhydrides, and esters. Specifically, maleyl chloride, maleimide,
Maleic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, glycidyl maleate, glycidyl methacrylate, glycidyl acrylate, vinyl glycidyl ether, allyl glycidyl ether,
Examples include glycidyl ether of hydroxyalkyl (meth)acrylate, glycidyl ether of polyalkylene glycol (meth)acrylate, and glycidyl itaconate. Among these, unsaturated dicarboxylic acids or unsaturated dicarboxylic anhydrides are preferably used. Particularly suitable are maleic acid, nadic acid, or acid anhydrides thereof. These modifiers are contained in an amount of 0.02% by weight or more, preferably 0.2 to 0.2% by weight, based on the polyolefin copolymer.
It is blended in a proportion of 2% by weight.

For example, when the above-mentioned polyolefin copolymer, modifier, and radical generator are blended and melt-kneaded, a graft reaction occurs and a modified polyolefin copolymer is produced. As the radical generator, known organic peroxides or diazo compounds can be used.

Specifically, benzoyl peroxide, α,α-bisbaroxy-p-diisopropylbenzene, dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, cumene hydroperoxide, azobisisobutylene Examples include lonitrile. The amount of radical generator used is 0.05% by weight or more, preferably 0.1% by weight based on the polyolefin copolymer.
~1.5% by weight.

Examples of the vinyl aromatic compound used to prepare the block copolymer constituting the modified block copolymer (2) include styrene, α-methylstyrene, and vinyltoluene, with styrene being particularly preferred. Examples of the olefin compound include butadiene, isoprene, 1,3-pentadiene, and the like, with butadiene and isoprene being particularly preferred. In the block copolymer, the vinyl aromatic compound and the olefin compound are contained in a weight ratio of 5/95 to 6.
It is present in a ratio of 0/40, preferably 10/90 to 30/70. This block copolymer is preferably used after being hydrogenated, and the hydrogenation is carried out so that the degree of unsaturation is 20% or less, preferably 10% or more.

A radically collapsible polymer that can form the graft portion of a modified block/graft copolymer is one in which a disintegration reaction (molecular scission) occurs in the presence of radicals in priority to a recombination reaction and a crosslinking reaction, and the polymer itself has a low It is a polymer that becomes molecular. These include polyisobutylene, polypropylene, polyα-methylstyrene, polymethacrylate, polymethacrylamide, polyvinylidene chloride,
Cellulose, cellulose derivatives, homopolymers such as polytetrafluoroethylene and polytrifluorochloroethylene, or copolymers such as butyl rubber obtained by copolymerizing polyisobutylene and 1 to 3% isoprene, and copolymers of ethylene and propylene. Among them, butyl rubber is particularly suitable. When a radically collapsible polymer is used, the block copolymer and radically collapsible polymer are used in a weight ratio of 20:1 to 1:2.

The unsaturated carboxylic acids and derivatives thereof used to modify the above block copolymers and block/graft copolymers include the same unsaturated carboxylic acids and derivatives thereof as those used to obtain the modified polyolefin copolymers described in (1) above. Any acid and its derivatives can be used. The modifier is 0.02% by weight based on the total amount of block copolymer or block copolymer and radically decomposable polymer.
The above content is preferably 0.1 to 2% by weight.

The modified block copolymer is produced by melt-kneading the block copolymer (preferably hydrogenated) and the modifier together with a radical generator.

The modified block/graft copolymer can be obtained by blending a radically decomposable polymer in addition to the above block copolymer and modifier, and melt-kneading the mixture in the same manner. As the radical generator, the same radical generator as used in preparing the modified polyolefin copolymer described in (1) above can be used. The amount of the radical generator used is 0.05% by weight or more, preferably 0.1 to 1.5% by weight, based on the total amount of the block copolymer or the block copolymer and the radically decomposable polymer.

When the above-mentioned modified polyolefin copolymer (2) and/or (2) modified block copolymer (modified block/graft copolymer) is contained in the inner layer together with MXD-6, MXD-6 and these modified The content ratio with the polymer is 15:85 to 100:0, preferably 4
The ratio is 0:60 to 95:5. MXD-6-1) If the amount is too low, the gas barrier properties will be poor and the tubular body cannot be used for fluorocarbon gas or gasoline. In order to impart flexibility to the obtained tubular body, it is preferable that the above-mentioned modified polymer is contained.

The inner layer of the tubular body of the present invention may contain various polymers other than the above-mentioned modified polymers in order to further impart flexibility, and may also contain other additives. Polymers for imparting flexibility include soft rubber materials, thermoplastic elastomers, and elastic modulus of 12,000.
kg10+! Examples include the following relatively soft thermoplastic resins. Examples of the soft rubber materials include styrene-butadiene rubber, chloroprene rubber, butyl rubber, IJ rubber, ethylene-propylene rubber, acrylic rubber, urethane rubber, chlorosulfonated ethylene chloroprene rubber, and fluororubber. Examples of thermoplastic elastomers include polyester elastomers, polyamide elastomers, olefin elastomers, vinyl chloride elastomers, urethane elastomers, and styrene elastomers.

Additives include dyes, pigments, nucleating agents, heat resistant agents, weathering agents,
Includes flame retardants, foaming agents, etc.

The modified polyester elastomer contained in the outer layer of the tubular body of the present invention is obtained by reacting a polyester elastomer with a monomer selected from unsaturated carboxylic acids and derivatives thereof, as described above. Examples of the polyester elastomer used here include polyester-polyether block copolymers, polyester type block copolymers, and the like.

The above polyester-polyether block copolymer is
It is a block copolymer that has the properties of a rubber-like elastic body because polyester is used as a hard segment and polyether is used as a soft segment, and these segments are arranged alternately and repeatedly.

The acids and alcohols constituting such polyester units are mainly aromatic dicarboxylic acids and alkylene glycols having 2 to 15 carbon atoms, respectively. Specific examples of dicarboxylic acids include terephthalic acid, isophthalic acid, ethylene bis(pt+cybenzoic acid), naphthalene dicarboxylic acid, adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, p-(β-hydroxyethoxy )
Examples include benzoic acid. Specific examples of alcohol include ethylene glycol, propylene glycol, tetramethylene glycol, pentamethylene glycol, 2.
Examples include 2-dimethyltrimethylene glycol, hexamethylene glycol, tetramethylene glycol, cyclohexane dimetatool, cyclohexane jetanol, benzenedimetatool, benzenedethanol, and the like. The above acid and alcohol have a melting point of 2 when made into polyester with a molecular weight that has fiber-forming ability.
It is suitable to have a temperature of 00°C or higher.

The polyether unit, which is the soft segment of the block copolymer, is a polyoxyalkylene glycol having an average molecular weight of about 500 to 5,000.

The monomer unit of this polyoxyalkylene glycol unit is an oxyalkylene group in which the alkylene group has 2 to 9 carbon atoms. Specifically, preferred examples include poly(oxyethylene) glycol, poly(oxypropylene) glycol, poly(oxytetramethylene) glycol, and the like. Polyether alone,
It may be a random copolymer, a block copolymer, or a mixture of two or more types of polyethers. Furthermore, the polyether may have a small amount of aliphatic group, aromatic group, etc. in its molecular chain. It may also be a modified polyether containing sulfur, nitrogen, phosphorus, or the like.

The polyester-polyether block copolymer contains 1 to 85% by weight of polyether units, preferably 5 to 80% by weight.
% by weight, and the polyester units are 99 to 15
It is contained in an amount of 95 to 20% by weight, preferably 95 to 20% by weight.

Examples of polyester block copolymers include those obtained by reacting crystalline aromatic polyesters with lactones. Examples of the crystalline aromatic polyester include polymers mainly having ester bonds or ester bonds and ether bonds, having at least one type of aromatic group as a main repeating unit, and having a hydroxyl group at the end of the molecule. . The crystalline aromatic polyester preferably has a melting point of 150° C. or higher when formed into a polymer with a high degree of polymerization. When the polyamide resin composition of the present invention is used as a molding material, a polymer having a molecular weight of 5,000 or more is preferable, but when it is used for an adhesive or a coating agent, a polymer with a molecular weight of 15,000 or less may be used. Preferred specific examples of the crystalline aromatic polyester include homopolyester, polyester ether,
It can be found in copolymerized polyesters, copolymerized polyester ethers, etc. Examples of homopolyesters include polyethylene terephthalate, polytetramethylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene-2°6-naphthalate, and the like. Examples of polyester ethers include polyethyleneoxybenzoate, poly-p-phenylene bisoxyethoxy terephthalate, and the like. Examples of the copolymerized polyester or copolymerized polyester ether include polymers mainly having tetramethylene terephthalate units or ethylene terephthalate units and further having other copolymerization components. Such copolymerization components include tetramethylene terephthalate units, ethylene isophthalate units, tetramethylene adipate units, ethylene adipate units, tetramethylene sebacate units, ethylene sebacate units, 1,4-cyclohexylene dimethylene terephthalate units, Tetramethylene-p-oxybenzoate unit, ethylene-p
-Oxidibenzoate units and the like are exemplified. The copolymerized polyester and copolymerized polyester ether preferably contain 60 mol% or more of tetramethylene terephthalate units or ethylene terephthalate units.

As the lactone, which is the other component forming the polyester type block copolymer, ε-caprolactam is most preferred, but enantlactone, caprylolactone, etc. can also be used. Two or more types of these lactones may be used.

The polyester type block copolymer contains the crystalline aromatic polyester and lactones in a weight ratio of 97/3 to 5/9.
It is obtained by copolymerization using a ratio of 95%. Preferably, this weight ratio is 9515 to 30/70. During the above copolymerization, a catalyst is added if necessary, and the mixture is heated and mixed to allow the reaction to proceed. The polyester elastomers (polyester-polyether block copolymers and/or polyester type block copolymers) thus obtained may be used alone or in combination of two or more.

Modifiers to be reacted with polyester elastomers to obtain modified polyester elastomers include unsaturated carboxylic acids and their derivatives used in the preparation of the modified polyolefin copolymers, modified block copolymers, and modified block/graft copolymers. Either can be used.

These modifiers are used in amounts ranging from about 0.01 to about 20% by weight, preferably from about 0.02 to about 10% by weight, based on the polyester elastomer. If the weight is less than 0.01 weight, the adhesiveness between the inner layer and the outer layer of the resulting tubular body is poor, and they are likely to peel off when bent. If it exceeds 20% by weight, gelation tends to occur during the graft reaction. For example, by blending the above polyester elastomer, a modifier, and a radical generator and melt-kneading them, a graft reaction occurs and a modified polyester elastomer is obtained. As the radical generator, compounds similar to those used in preparing the modified polyolefin copolymer can be used. The amount of radical generator used is 0.05% by weight or more, preferably 0.1 to 1.5% by weight based on the polyester elastomer.
Weight%.

The polyamide resin tubular body of the present invention is prepared, for example, by a coextrusion method by connecting an extruder to each of a pair of tube dies arranged concentrically. At this time, the die for forming the inner layer of the tubular body contains MXD-6 and, if necessary, a modified polyolefin copolymer, a modified block copolymer, a modified block/graft copolymer, other polymers, additives, etc. Prepare and melt and knead. A die for forming the outer layer is charged with the modified boester elastomer and, if necessary, other polymers, additives, etc., and melt-kneaded. Two or more dies for forming the inner layer and the outer layer are connected as necessary, and the inner layer and the outer layer are each formed of one or more types of polymer. Here, for example, when using a mixture of MXD-6 and a modified polyolefin copolymer in the inner layer, several methods can be adopted. For this purpose, there is a method of mixing pellets of MXI)-6 and pellets of a modified polyolefin copolymer prepared in advance as described above; MXD-6;
MXD-6, polyolefin copolymer (unmodified), modifier, and radical generator are charged into an extruder and melt-kneaded. There is a method of forming a modified polyolefin copolymer and simultaneously mixing it with MXD-6. A similar method can be employed when mixing a modified block copolymer and a modified block/graft copolymer.

The thickness of the inner layer of the polyamide resin tubular body of the present invention is 0.
It is preferably 1 mm or more and 1.0 mm or less. Inner layer thickness is 0
．． If it is less than 1+++n+, the gas barrier properties will be poor, and 1
, Omm, the resulting tubular body lacks flexibility.

In the polyamide resin tubular body of the present invention, since the inner layer and the outer layer are in contact with each other in a molten state during molding, the MXD-
The terminal amino group of No. 6 and the functional group of the modified polyester elastomer contained in the outer layer (for example, a carboxyl group derived from an unsaturated carboxylic acid) react or interact with each other. Therefore, the adhesion between the inner layer and the outer layer is improved,
Even when the obtained tubular body is bent, the inner layer and outer layer do not separate.

When the inner layer contains a modified polyolefin copolymer, a modified block copolymer, or a modified block/graft copolymer, the functional groups (for example, carboxyl groups resulting from unsaturated carboxylic acids) of these resins and MXD-
The terminal amino group of 6 reacts or interacts in the molten state.

Therefore, uniform dispersion of these modified polymers and MXD-6 is promoted, and the inner layer has excellent oil resistance and fluorocarbon gas resistance, as well as more flexible properties.

In this way, the polyamide resin tubular body of the present invention has MX
Since D-6 is contained in the inner layer, the permeability of fluorocarbon gas, especially fluorocarbon 22, is low and no deterioration occurs. Oil resistance,
It also has excellent heat resistance. Moreover, since the outer layer contains polyester elastomer, it is highly flexible and has good adhesion between the inner layer and the outer layer. Such polyamide resin tubular bodies are used for refrigerant tubes in near controllers for automobiles,
It can be used in many fields, such as gasoline supply tubes and household refrigerator tubes.

(Margin below) (Example) The present invention will be described below with reference to Examples.

Examples 1-1 to 1-4 (A) Preparation of modified polyester elastomer As the polyester elastomer (unmodified), ■ polyether-polyester elastomer of polytetramethylene glycol and polytetramethylene terephthalate (Perbrene P90B manufactured by Toyobo Co., Ltd.) ), and (2) a polyester block copolymer of polycaprolactone and polytetramethylene terephthalate (Belprene S-1000 manufactured by Toyobo Co., Ltd.) were used.

Maleic anhydride-modified polyester elastomers (1) and (2) (referred to as (1)' and (2)'', respectively) were synthesized as follows.

100 parts by weight of (1) or (2), 0.5 parts by weight of maleic anhydride, and 0.3 parts by weight of digmeal peroxide were uniformly mixed using a mixer. This mixture was supplied to a 30+y+m twin-screw extruder, and a maleic anhydride modification reaction was carried out at a cylinder temperature of 200 to 230°C. The reaction product thus obtained was dried in a vacuum dryer at 80° C. for 12 hours to obtain pellets of modified polyester elastomer and polymer.

(B) Preparation of polyamide resin tubular body Extruder (1) (30mmφ) is connected to the inner layer side of a pair of tube dies arranged concentrically, and extruder (II) (30+++mφ) is connected to the outer layer side. did.

The extruder (H is polymethaxylene adipamide (indicated as MXD-6 in the table; pellets after vacuum drying at 100°C for 16 hours are used), and the extruder (II) is the (A) item. Modified polyester elastomer obtained from■
I prepared ゛ or ■゛. The cylinder temperature of the extruder (I) was set to 260°C and that of the extruder (■) to 220°C, coextrusion was carried out, and the inner diameter was 10+n+n using the vacuum box sizing method.

A tubular body having an outer diameter of 12 mm and an inner layer and an outer layer having the configuration shown in Table 1 was obtained.

(C) Evaluation of polyamide resin tubular body: The tubular body obtained in section (B) was bent to perform a flexibility test. Table 1 shows cases in which it is easily bent and maintains the bent shape with a mark of ○, and cases in which the bent shape cannot be maintained with a mark of x. Furthermore, we observed the interface between the inner layer and outer layer when bent,
The presence or absence of peeling was examined. The results are shown in Table 1.

Next, prepare the new tubular body 80 cm obtained in section (B), and conduct a fluorocarbon gas permeation test (high pressure) on the hose assembly specified in the section of automobile cooling equipment hoses (JRA2001-1976) specified by the Japan Refrigeration and Air Conditioning Industry Association. Apply mutatis mutandis, Freon 22
The permeability was tested. The above tubular body was filled with Freon 22 and left in an air constant temperature bath at 100° C. for 96 hours, and the weight difference before and after leaving was calculated to determine the gas permeability (g/tn/72 hours). The results are shown in Table 1.

Comparative Examples 1-1 to 1-2 The same procedure as in Examples 1-1 to 1-4 was carried out except that an unmodified polyester elastomer (■ or ■) was used instead of the modified polyester elastomer. A tubular body having an inner layer and an outer layer having the configuration shown in the table was obtained. Using this, tests were conducted in the same manner as in Examples 1-1 to 1-4. The results are shown in Table 1.

Comparative Examples 1-3 to 1-4 Examples 1-1 to 1-4 by changing the thickness of the inner layer and outer layer
A tubular body was prepared according to . Using this, tests were conducted in the same manner as in Examples 1-1 to 1-4. The results are shown in Table 1.

Comparative Example 1-5 A single-layer tubular body made only of polymethaxylylene adipamide was prepared. Using this, tests were conducted in the same manner as in Examples 11 to 1-4. The results are shown in Table 1.

Comparative Example 1-6 A single-layer tubular body made only of unmodified polyester elastomer (2) was prepared. Using this, Examples 1-1 to 1-
The test was conducted in the same manner as in 4. The results are shown in Table 1.

Comparative Example 1-7 A single-layer tubular body made only of unmodified polyester elastomer (2) was prepared. Using this, Examples 1-1 to 1-
The test was conducted in the same manner as in 4. The results are shown in Table 1.

(The following is a blank space) It can be seen from Table 1 that the polyamide resin tubular body of the present invention has a very low transmittance of Freon 22, is highly flexible, and does not exhibit peeling between the resin layers even when bent.

On the other hand, a tubular body made of a single layer of polymethaxylylene adipamide (Comparative Example 1-5) has a low Freon 22 permeability but lacks flexibility. The tubular body made of a single layer of modified polyester elastomer (Comparative Examples 1-6.1~?) has a very high permeability of fluorocarbon gas. When an unmodified polyester elastomer is used for the outer layer (Comparative Example 1-1)
．． 1. -2) The interlayer adhesion between the inner layer and the outer layer is low. Comparative Example 1-3.1-4) Lack of flexibility when the inner layer made of polymethaxylylene adipamide exceeds 172 mm in total. In addition to the above, an attempt was made to test the Freon gas permeability by molding a tubular body with a thickness of 0.1.5 mm from a single layer of polymethaxylylene adipamide, but the tube ruptured under gas pressure and measurement was impossible.

Examples 2-1 to 2-6 (A) Preparation of modified polyolefin copolymer and resin pellets for inner layer Ethylene propylene rubber (BP911P, manufactured by Japan Synthetic Rubber) was used as the polyolefin copolymer (unmodified).
was used. 100 parts by weight of this polyolefin copolymer,
0.5 parts by weight of maleic anhydride and 0.3 parts by weight of dicumyl peroxide were triblended. This mixture was supplied to a single-screw extruder with a diameter of 40++ UN, and a maleic anhydride modification reaction was carried out at a cylinder temperature of 200°C.

70 parts by weight of polymethaxylene adipamide and 30 parts by weight of the modified polyolefin copolymer obtained by the above method were triblended and fed to a twin screw extruder with a diameter of 30 mm,
The mixture was melt-kneaded at a cylinder temperature of 260°C to obtain pellets.

This pellet was dried in a vacuum dryer at 70°C for 16 hours.

(B) Preparation Example 1 of modified polyester elastomer
Maleic anhydride-modified polyester elastomer ■° or ■゛ was prepared in the same manner as in Sections 1 to 1-4 (A).

(C) Preparation and evaluation of polyamide resin tubular body Examples 1-1 to 1 -4 A tubular body was prepared according to Section (B). Here, the extruder (1) was charged with a resin pellet for the inner layer, and the extruder (■) was charged with a modified polyester elastomer pellet, to obtain a tubular body having an inner layer and an outer layer having the structures shown in Table 2. Example 1 using this
Tests were conducted in the same manner as in -1 to 1-4. The result is the second
Shown in the table.

Comparative Examples 2-1 to 2-4 Using unmodified polyester elastomer ■ or ■ (same as those described in Comparative Examples 1-1 and 1-2) in place of the modified polyester elastomer, the compositions shown in Table 2 were prepared. A tubular body having an inner layer and an outer layer was obtained. Using this, tests were conducted in the same manner as in Examples 1-1 to 1-4. The results are shown in Table 2.

Comparative Example 2-5 Example 2-5 except that dicumyl peroxide was not added in the process of preparing the modified polyolefin copolymer.
It is the same as 1. Example 1-1 using the obtained tubular body
The test was conducted in the same manner as in 1-4. The results are shown in Table 2.

Comparative Example 2-6 The same as Example 2-1 except that maleic anhydride and dicumyl peroxide were not added in the process of preparing a modified polyolefin copolymer. Tests were conducted in the same manner as in Examples 1-1 to 1-4 using the obtained tubular bodies. The results are shown in Table 2.

Comparative Example 2-7 Nylon 66 was used instead of polymethaxylene adipamide, and the kneading temperature with the modified polyolefin copolymer was set to 27
The procedure was the same as in Example 2-1 except that the temperature was 5°C. Tests were conducted in the same manner as in Examples 1-1 to 1-4 using the obtained tubular bodies. The results are shown in Table 2.

Comparative Example 2-8 Nylon 12 was used instead of polymethaxylene adipamide, and the kneading temperature with the modified polyolefin copolymer was set to 21
The procedure was the same as in Example 2-1 except that the temperature was 0°C.

Tests were conducted in the same manner as in Examples 1-1 to 1-4 using the obtained tubular bodies. The results are shown in Table 2.

(The following is a blank space) From Table 2, it can be seen that the polyamide resin tubular body of the present invention has a very low transmittance of Freon 22, is highly flexible, and no peeling between the resin layers is observed even when bent. . On the other hand, the tubular body in which unmodified polyester elastomer was used for the outer layer (Comparative Example 2-1.2-2)
Due to poor adhesion between the inner and outer layers, delamination occurs due to bending. When the outer layer is thick and the inner layer is thin (Comparative Example 2-
3.2-4), peeling due to bending is unlikely to occur, but
lacks flexibility. When the polyolefin copolymer contained in the inner layer is not modified (Comparative Example 2-5.2-6), it has poor compatibility with polymethaxylene adipamide, phase separation is observed, and the permeation of fluorocarbon gas is rate becomes higher. When a general-purpose polyamide resin is used instead of polymethaxylene adipamide (Comparative Example 2-7.2-8), it has flexibility and does not peel between layers even when bent, but High transmittance.

Examples 3-1 to 3-2 (A) Preparation of modified block/graft copolymer and resin pellets for inner layer Kraton G-1657 as hydrogenated block copolymer
(manufactured by Showa Shell Chemical Co., Ltd.) 100 parts by weight, Köhler-[! After tri-blending 100 parts by weight of X5263 (manufactured by Hardman, USA), 0.5 parts by weight of maleic anhydride, and 0.3 parts by weight of dicumyl peroxide, the mixture was subjected to uniaxial extrusion with a diameter of 40 mm at a cylinder temperature of 200°C. The mixture was melt-kneaded using a machine to obtain a modified block/graft copolymer.

30 parts by weight of the polymethaxylene adipamide furo compound and the above block/graft copolymer were triblended, fed to a twin-screw extruder with a diameter of 30 mm, and melt-kneaded at a cylinder temperature of 260°C to obtain pellets. Ta. The pellets were dried in a vacuum dryer at 70°C for 16 hours.

(B) Preparation Example 1 of modified polyester elastomer
1 to 1-4 Maleic anhydride-modified polyester elastomer ``■'' or ``■'' was prepared in the same manner as in Section (A).

(C) Preparation and evaluation of polyamide resin tubular body Examples 1-1 to 1 -4 A tubular body was prepared according to Section (B). Here, the extruder (I) was charged with a resin pellet for the inner layer, and the extruder (■) was charged with a modified polyester elastomer pellet, to obtain a tubular body having an inner layer and an outer layer having the structures shown in Table 3. Example 1 using this
Tests were conducted in the same manner as in -1 to 1-4. The result is the third
Shown in the table.

Examples 3-3 to 3-4 Modified block without using radical decomposable polymer
Graft copolymer B was obtained and used to prepare tubular bodies having the configurations shown in Table 3. Using this, Example 1-
Tests were conducted in the same manner as in 1 to 1-4. The results are shown in Table 3.

According to Examples 3-1 and 3-2, the thicknesses of the inner layer and the outer layer were varied to obtain tubular bodies having the configurations shown in Table 3. Using this, tests were conducted in the same manner as in Examples 1-1 to 1-4. The results are shown in Table 3.

Comparative Examples 3-1 to 3-2 Using unmodified polyester elastomer ■ or ■ (same as those described in Comparative Examples 1-1 and 1-2) in place of the modified polyester elastomer, the compositions shown in Table 3 were prepared. A tubular body having an inner layer and an outer layer was obtained. Using this,
Tests were conducted in the same manner as Examples 1-1 to 1-4. The results are shown in Table 3.

According to Examples 3-1 and 3-3, the thicknesses of the inner layer and the outer layer were varied to obtain tubular bodies having the configurations shown in Table 3. Using this, tests were conducted in the same manner as in Examples 1-1 to 1-4. The results are shown in Table 3.

Comparative Example 3-5 Example 3-1 except that maleic anhydride was not added in the process of preparing the modified block/graft copolymer.
It is similar to Examples 1-1~ using the obtained tubular body
The test was conducted in the same manner as in 1-4. The results are shown in Table 3.

Comparative Example 3-6 Same as Example 3-1 except that maleic anhydride and dicumyl peroxide were not added in the process of preparing the modified block/graft copolymer. Tests were conducted in the same manner as in Examples 1-1 to 1-4 using the obtained tubular bodies. The results are shown in Table 3.

Comparative Example 3-7 The same as Example 3-1 except that nylon 66 was used instead of polymethaxylene adipamide and the kneading temperature with the modified block graft copolymer was 275°C.

Tests were conducted in the same manner as in Examples 1-1 to 1-4 using the obtained tubular bodies. The results are shown in Table 3.

Comparative Example 3-8 The same as Example 3-1 except that nylon 12 was used instead of polymethaxylene adipamide and the kneading temperature with the modified block graft copolymer was 210°C.

Tests were conducted in the same manner as in Examples 1-1 to 1-4 using the obtained tubular bodies. The results are shown in Table 3.

(The following is a blank space) From Table 3, it can be seen that the polyamide resin tubular body of the present invention has a very low transmittance of Freon 22, is highly flexible, and does not exhibit peeling between the resin layers even when bent. . On the other hand, the tubular body in which unmodified polyester elastomer was used for the outer layer (Comparative Example 3-1.3-2)
Due to poor adhesion between the inner and outer layers, delamination occurs due to bending. When the outer layer is thin and the inner layer is thick (Comparative Example 3-
3.3-4), peeling due to bending is unlikely to occur, but
lacks flexibility. When the block copolymer contained in the inner layer is not modified (Comparative Example 3-5.3-6), the compatibility with polymethaxylene adipamide is poor, phase separation is observed, and the permeation of fluorocarbon gas is rate becomes higher. When a general-purpose polyamide resin is used instead of polymethaxylene adipamide (Comparative Example 3-7.3-8), it has flexibility and does not peel between layers even when bent, but High transmittance.

(Effects of the Invention) According to the present invention, the polyamide resin tubular body has extremely low permeability to fluorocarbon gas, excellent chemical resistance, heat resistance, and oil resistance, and is flexible enough to be easily processed. provided. Such a polyamide resin tubular body is
Duplex for refrigerant in near conditioner for automobiles,
It can be used in many fields, such as gasoline supply tubes and household refrigerator tubes.

that's all

Claims (1)

[Claims] 1. The inner layer contains a metaxylylene group-containing polyamide resin or a metaxylylene group-containing polyamide resin and other polymers, and the outer layer is obtained by reacting a monomer selected from unsaturated carboxylic acids and derivatives thereof with a polyester elastomer. Polyamide resin tubular body containing modified polyester elastomer.