JPH0238793A - Multilayer plastic tube - Google Patents

Abstract

PURPOSE:To improve a barrier against gas fluid by having one layer of an inner peripheral tube formed of the drawn film of a composition composed of polyamide containing a xylelene group and polyalkylene terephthalate. CONSTITUTION:A multilayer plastic tube is formed of an inner peripheral tube (a) and an outer peripheral tube (b). One layer of the inner peripheral tube (a) is formed of the drawn film of a composition composed of polyamide containing a xylelene group and polyalkylene terephthalate having ethylene terephthalate as a main component unit. This multilayer plastic film is thus made excellent as a barrier against gas fluid such as Freon gas as well as in flexibility.

Description

[Detailed description of the invention] 1 prisoner! ”1 (ice amount The present invention relates to a novel multilayer plastic tube.

More particularly, the present invention relates to multilayer plastic tubing suitable for transporting gaseous fluids such as Freon gas.

Technical Background and Problems Conventionally, multilayer plastic tubes such as hoses used to transfer gas fluids such as Freon gas, especially hoses used to transfer Freon gas from automobile coolers, have been made of polyamide-based resin hoses or polyamide-based resin hoses. Vulcanized rubber tubes are often used in which the inner circumferential tube is made of acrylonitrile-butadiene copolymer (tolyl rubber) and the outer circumferential tube is made of polychloroprene (taloloprene rubber).

A second example of such a conventional multilayer plastic tube
FIG. 2 is a cross-sectional view of a conventional multilayer plastic tube, which consists of an inner tube a and an outer tube b, which further includes a reinforcing yarn layer b. -1 and a cover layer b-2°.

The use of multilayer plastic tubes made of polyamide resin as described above for transporting Freon gas, etc.
This is because such multilayer plastic tubes are lightweight, inexpensive, have excellent gas barrier properties against Freon gas, and have excellent oil resistance, which is important for automobiles. The tube is used because this multilayer plastic tube has both the excellent Freon gas barrier properties of nitrile rubber and the excellent oil resistance of chloroprene rubber.

However, multilayer plastic tubes with layers made of polyamide resin have poor flexibility, and if kept at high temperatures for long periods of time, the plasticizer added to the resin will scatter, resulting in further hardening. Further, it has problems such as embrittlement phenomenon occurring at low temperatures. In addition, multilayer plastic tubes with layers made of nitrile rubber-chloroprene rubber resin have excellent visibility, but cannot be said to have sufficiently high gas barrier properties against all Freon gases. However, depending on the type of Freon gas, there was a problem in that the permeability was high.

Due to the above circumstances, it has excellent Freon gas barrier properties, does not lose flexibility even when used under harsh conditions, and
It has been desired to develop a multilayer plastic tube that can maintain good Freon gas barrier properties over a long period of time.

The present invention aims to solve the problems associated with the prior art as described above, and is aimed at solving the problems associated with the prior art as described above. The purpose of the present invention is to provide a multilayer plastic tube that has excellent Freon gas barrier properties, is lightweight, and has excellent flexibility and visibility by solving the problems that tubes have.

几匪Ω 1 A multilayer plastic tube according to the present invention is a multilayer plastic tube consisting of an inner circumferential tube and an outer circumferential tube covering the inner circumferential tube, in which at least one layer of the inner circumferential tube is made of xylylene group-containing polyamide, It is characterized by being composed of a stretched film of a composition consisting of polyalkylene terephthalate whose main constituent unit is ethylene terephthalate.

The multilayer plastic tube according to the present invention has particularly excellent barrier properties against gas fluids such as Freon gas, and excellent flexibility. Therefore, by using the multilayer plastic tube of the present invention in a device such as a cooler using 7 Leon gas, the usable period of the device can be greatly extended.

1. Hereinafter, the multilayer plastic tube of the present invention will be specifically explained.

The present invention was made based on the finding that a stretched film of a resin composition comprising a xylylene group-containing polyamide and a specific polyalkylene terephthalate exhibits extremely excellent gas barrier properties against Freon gas.

The xylylene group-containing polyamide used in the present invention has metaxylylene diamine or a mixed xylylene diamine component unit containing metaxylylene diamine and paraxylylene diamine as the main component unit of the diamine component, and has 6 to 12 carbon atoms. This is a polyamide containing an aliphatic dicarboxylic acid as the main dicarboxylic acid component unit.

Specific examples of the aliphatic dicarboxylic acid having 6 to 12 carbon atoms, which is the main component of the dicarboxylic acid component constituting the xylylene group-containing polyamide, include adipic acid, pimelic acid, speric acid, and sepacic acid. be able to.

The content of metaxylylene diamine or a mixed xylylene diamine containing metaxylylene diamine and paraxylylene diamine in the diamine component of the xylylene group-containing polyamide is usually in the range of 50 mol% or more, preferably 70 mol% or more. The content of the aliphatic dicarboxylic acid having 6 to 12 carbon atoms in the dicarboxylic component of the xylylene group-containing polyamide is usually 50 mol% or more, preferably 70 mol% or more.

Specifically, other diamine components that can be used in combination with meta-xylylene diamine or mixed xylylene diamine containing meta-xylylene diamine and para-xylylene diamine, which is the main component of the diamine component of the xylylene group-containing polyamide, include: is an aliphatic diamine biverazine bisgropylamine such as hexamethylene diamine, 2,4,4-trimethylhexamethylene diamine,
Diamines containing different rings or atoms such as neopentyl glycol bisprobylamine, aromatic diamines such as parabis(2-aminoethyl)benzene, or polyethers containing terminal amine groups such as polyethylene glycol having terminal amino groups, etc. can be given.

In addition, dicarboxylic acids that can be used in combination with the aliphatic dicarboxylic acid having 6 to 12 carbon atoms, which is the main component of the dicarboxylic acid component of the xylylene group-containing polyamide, include aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid. Alternatively, polyethers containing terminal carboxyl groups such as polyethylene glycol having terminal carboxyl groups can be used.

Further, meta-xylylene diamine or a mixed xylylene diamine containing meta-xylylene diamine and para-xylylene diamine, which is the main component of the diamine component of the xylylene group-containing polyamide, and a carbon atom number of 6 to 12, which is the main component of the dicarboxylic acid component. Lactams such as ε-caprolactam, ε-
Omega-aminocarboxylic acids such as aminocaproic acid and para-aminomethylbenzoic acid can also be used.

In the present invention, it is preferable to use a xylylene group-containing polyamide having a molecular weight such that the relative viscosity measured in metacresol at 25°C is in the range of 1°O to 4.0.

The polyalkylene terephthalate used in the present invention is
A polyester whose main constituent unit is ethylene terephthalate.

The content of ethylene terephthalate structural units in the polyalkylene terephthalate is usually 50 mol% or more, preferably 70 mol% or more. The dicarboxylic acid component units constituting the polyalkylene terephthalate may contain a small amount of other aromatic dicarboxylic acid component units in addition to the terephthalic acid component units.

Specific examples of aromatic dicarboxylic acid component units other than the terephthalic acid component unit include isophthalic acid, phthalic acid, and naphthalene dicarboxylic acid. The diol component units constituting the polyalkylene terephthalate may contain small amounts of other diol component units in addition to ethylene glycol component units.

Specifically, other diol component units other than the ethylene glycol component unit include 1,3-propanediol, 7,4-butanediol, neopentyl glycol,
Cyclohexanediol, cyclohexane dimetatool, 1,4-bis(β-hydroxyethoxy)benzene,
1,3-bis(β-hydroxyethoxy)benzene, 2
, 2-bis(4-β-hydroxyethoxyphenyl)sulfone and the like can be exemplified by diol component units having 3 to 15 carbon atoms.

The composition of the constituent components of the polyalkylene terephthalate is:
The content of terephthalic acid component units is usually in the range of 50 to 100 mol%, preferably 70 to 100 mol%, and the content of aromatic dicarboxylic acid component units other than terephthalic acid component units is usually 0 to 50 mol%. , preferably in the range of 0 to 30 mol%, and the content of ethylene glycol component units is usually 50 to 100 mol%, preferably 70 to 100 mol%.
The content of diol component units other than ethylene glycol component units is usually 0 to 50 mol%, preferably 0 to 30 mol%.

Furthermore, the intrinsic viscosity [η
] (Value measured at 25°C in a phenol-tetrachloroethane mixed solvent (weight ratio 1/1)) is usually 0.5 to 1.
．． 5dj/g, preferably in the range of 0.6 to 1.2dj/+r.

Next, a stretched film of the composition of the xylylene group-containing polyamide and the polyalkylene terephthalate that constitutes at least one layer of the inner peripheral tube of the multilayer plastic tube of the present invention will be described.

In the composition, the blending ratio of the xylylene group-containing polyamide and the polyalkylene terephthalate is not particularly limited, but usually the xylylene group-containing polyamide is 2 to 1003! The amount ranges preferably from 5 to 80 parts by weight, particularly preferably from 10 to 60 parts by weight. In addition to the polyalkylene terephthalate and the polyhydroxypolyether, the composition may also contain conventionally known nucleating agents, inorganic fillers, lubricants, lagging agents, anti-blocking agents, stabilizers, antistatic agents, etc. Appropriate amounts of various additives such as violets, antifogging agents, and pigments may be blended.Furthermore, there are no particular restrictions on the method for producing the composition, and many commonly used mixing methods may be used. Among these methods, it is preferable to adopt a method in which the xylylene group-containing polyamide and the polyalkylene terephthalate are dried, mixed under melting, and then extruded.

The resulting composition is then molded into a sheet by a conventionally known method such as compression molding or extrusion molding using a T-die.

The sheet obtained in this way can be used as is or -
After the polyalkylene terephthalate is cooled and solidified to a temperature below the glass transition temperature, it is stretched at a temperature within the range of the glass transition temperature or melting point of the polyalkylene terephthalate, preferably at a temperature within the range of the glass transition temperature or 80° C. higher than the glass transition temperature. .

Such stretching methods include a method of stretching in the -axial direction (-axial stretching method), a method of stretching in the longitudinal direction and then further stretching in the transverse direction (biaxial stretching method), a method of stretching in the longitudinal direction and then in the transverse direction (biaxial stretching method), A method of simultaneously stretching in the transverse axis direction (simultaneous biaxial stretching method), a method of repeating sequential stretching in any one direction after biaxial stretching, a method of further stretching in both directions after biaxial stretching, and a method of stretching the sheet and metal. An example is a so-called vacuum forming method in which stretch forming is performed by reducing the pressure in the space between the mold and the mold.

When the stretched film is a uniaxially stretched film, the stretching ratio is usually 1.1 to 10@, preferably 1.
．． It is in the range of 2 to 8 times, particularly preferably 1.5 to 7 times. When the stretched film is a biaxially stretched film, the stretching ratio in the longitudinal direction is usually 1.1 to 8 times, preferably 1.2 to 7 times, particularly preferably 1.5 to 6 times. In the vertical axis direction, it is usually 1.1 to 8 times, preferably 1.2 to 7 times, particularly preferably 1.5 to 6 times.

After the film thus obtained is stretched, it is usually subjected to an appropriate short-time heat treatment within the above temperature range or at a temperature higher than the stretching temperature.

By performing heat setting in this manner, a stretched film imparted with dimensional stability is produced.

The present invention is a multilayer plastic tube consisting of an inner circumferential tube and an outer circumferential tube surrounding the inner circumferential tube,
FIG. 1 shows a cross-sectional view of an example of the multilayer plastic tube of the present invention.

As shown in FIG. 1, the multilayer plastic tube of the present invention consists of an inner circumferential tube a and an outer circumferential tube b.

The multilayer plastic tube of the present invention is characterized in that the inner circumferential tube (a) is made of a stretched film of a composition made of xylylene group-containing polyamide and polyalkylene terephthalate, as described above.

In FIG. 1, an inner tube a includes an inner layer a-1, an intermediate layer a-1, and an intermediate layer a-1.
-2 and outer layer a-3, and the outer circumferential tube b has a two-layer structure of reinforcing yarn layer b-1 and cover layer b-2.

The multilayer plastic tube of the present invention is, for example, a multilayer plastic tube having the above structure,
At least one layer of the inner peripheral tube of such a tube is composed of a stretched film of a composition comprising the above-mentioned xylylene group-containing polyamide and polyalkylene terephthalate. In particular, in the multilayer plastic tube of the present invention, as shown in FIG. 1, the inner tube has a three-layer structure of an inner layer, an intermediate layer, and an outer layer, and a stretched film of the composition of the xylylene group-containing polyamide and polyalkylene terephthalate is used. It is preferable to use it as an intermediate layer in the inner circumferential tube. In this way, when the stretched film of the xylylene group-containing polyamide and polyalkylene terephthalate composition is used as an intermediate layer to form a sandwich-like protected structure, the multilayer plastic tube of the present invention is attached to the connecting fitting and the multilayer plastic It is preferable to use the tube with the end portion tightened, since this improves reliability against tube breakage.

When the intermediate layer of the inner circumferential tube of such a multilayer plastic tube is formed from a stretched film of a composition consisting of the above-mentioned xylylene group-containing polyamide and polyalkylene terephthalate, the resin forming the inner circumferential tube The material can be appropriately selected in consideration of resistance to gas fluids, such as less deterioration due to contact with gas fluids such as Freon gas. Examples of such resins include polyamide resins, acrylonitrile butadiene copolymers, polyvinylmethylsiloxane, polyepichlorohydrin, ethylene oxide-epichlorohydrin copolymers, ethylene propylene terpolymers, chlorinated and
Examples include conventionally used materials such as sulfonated polyethylene.

In addition, when the intermediate layer of the inner circumferential tube is formed of a stretched film of the composition consisting of the xylylene group-containing polyamide and polyalkylene terephthalate, the outer layer is made of a material that maintains the physical properties necessary for the resulting multilayer plastic tube. Such a material can be appropriately selected from commonly used resins and the like. In other words, the resins used to form such an outer layer include conventionally used resins such as chlorinated polyethylene, chlorinated/sulfonated polyethylene, ethylene propylene terpolymer, polychloroprene, fluororubber, polyamide resin, and polyester ether resin. I can list the materials that are used.

In the multilayer plastic tube of the present invention, the thickness of the inner circumferential tube as described above is appropriately set in consideration of various required characteristics of the resulting multilayer plastic tube, such as mechanical strength, flexibility, and gas barrier properties. I can do it, but
The thickness of the intermediate layer is 0.01 mm or more, preferably 0.02 ~
By setting it within the range of ll1I+, gas barrier properties against Freon gas will be improved. Further, in the plastic tube of the present invention, it is preferable that the inner layer of the inner peripheral tube has a thickness of 0.5 to 7 mm, and the outer layer has a thickness of 0.5 to 7+111 mm.

The inner circumferential tube as described above is covered with an outer circumferential tube.In the present invention, the outer circumferential tube may be made of a single resin layer, or may be covered with a reinforcing layer such as a reinforcing thread layer as shown in FIG. It may be composed of a layer, a coating for this layer, and a cover layer.

The resin used to form such a peripheral tube should be selected based on the mechanical strength, flexibility, and
It can be appropriately selected in consideration of characteristics such as weather resistance.

Examples of resins for forming such a peripheral tube (or a cover layer when forming reinforcing thread waste) include polyamide resin, polychloroprene, chlorinated/sulfonated polyethylene, ethylene propylene terpolymer,
Examples include polyester elastomers.

In addition, when providing a reinforcing thread layer, the reinforcing thread waste can be formed using resin fibers such as various polyester fibers.

The thickness of such a peripheral tube can be appropriately set in consideration of the intended use of the multilayer plastic tube of the present invention, but is usually 0.5 to 10 m5.

There are no particular restrictions on the method for producing a multilayer plastic tube using the stretched film of the composition of the present invention as at least one layer. A common method is to cover a tubular molded body with a stretched film of the above-mentioned composition, and then further cover it with a resin that will become an outer layer by extrusion molding. Further, if the resin constituting the inner circumferential tube obtained in this manner requires further post-treatment such as heat treatment for vulcanization reaction, appropriate post-treatment is performed.

After forming the inner circumferential tube as described above, a reinforcing yarn layer may be provided to cover the inner circumferential tube if necessary, and a cover layer may be further formed to form an outer circumferential tube. Furthermore, in addition to being formed from the reinforcing thread layer and the cover layer as described above, the outer circumferential tube may also be formed from a rubber layer reinforced with various fibers and/or various elastomeric resins.

The thus obtained multilayer plastic tube of the present invention is normally visible and has good gas barrier properties against Freon gas, so it can be used as a plastic tube for transporting gas fluids such as Freon gas. It can be preferably used as a hose.

The multilayer plastic tube of the present invention has particularly excellent barrier properties against gas fluids such as Freon gas, and is excellent in flexibility. Therefore, by using it as a hose for transferring Freon gas such as a cooler filled with 7 Leon gas, the usable period of the device such as the cooler can be greatly extended.

The multilayer plastic tube of the present invention is for indoor coolers,
Effectively used as a hose for automobile coolers and other coolers.

EXAMPLES] The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

In addition, in the Examples and Comparative Examples, performance evaluation of the tube and the layers constituting the tube was performed according to the following method.

The flexibility of the tube was measured by measuring the load required when both ends of a tube cut to a length of 30 mm were bent to the minimum bending radius, and converted into stress, which was used as a measure of visibility.

Freon gas permeation test is carried out by S A E (Societ
y of Autolotive Engineers
Inc.) According to the J51b standard, various Freon gases were placed in a tube cut into 30 cm length at 0.6±0.
1 g was sealed and left in an air thermostat at 60°C for 96 hours. After 24 hours, the change in weight was measured and the amount of permeation (g
/m/72 hours) was calculated.

Kansho'' ■2 A multilayer plastic tube of the present invention as shown in FIG. 1 was manufactured as follows.

40 parts of dried polymethaxylylene adipamide having a relative viscosity of 1.7 was mixed with 100 parts of dried polyethylene terephthalate (manufactured by Mitsui PET Resin ■, Mitsui PET J 025). Using an extruder equipped with a T-die for sheet forming, the mixture was
It was melted at 0° C., extruded as a sheet with a thickness of about 500 μm, rapidly cooled, and collected. This sheet was then biaxially stretched to approximately 3x3 using a biaxial stretching device. The thus biaxially stretched sheet was then heat set to produce a biaxially stretched film having a thickness of approximately 50 μm.

Next, the above-mentioned biaxially stretched film is wrapped around a tube (inner tube inner layer) a-1 prepared by extruding a nitrile rubber compound (1) as shown below so as to have an average of two turns to form an inner tube. After forming the middle Siff layer a-2, the inner tube middle layer a-2 made of this biaxially stretched film was coated with a nitrile rubber compound using an extruder to form the inner tube outer layer a-3. An inner peripheral tube a having a sandwich structure in which a biaxially stretched film layer was sandwiched between nitrile rubber layers was prepared.

A polyester cord (manufactured by Unitika ■: 10000//2) was wrapped around the outer periphery of the inner circumferential tube a of this sandwich structure to form an outer circumferential tube reinforcing yarn layer b-1 to reinforce the tube a, and further as follows. Cover layer b-
2 to obtain an unvulcanized multilayer tube.

This unvulcanized multilayer tube was cut into appropriate lengths and vulcanized in a steam oven at 145°C for a period of time to obtain a multilayer plastic tube. The obtained multilayer plastic tube is the first
It had a cross-sectional shape as shown in the figure.

That is, in FIG. 1, the middle layer a-2 of the inner tube
The nitrile rubber layer sandwiching the two-wheel stretched film forming the inner layer a-1 has a thickness of 2.5 m + a Y'', and the outer layer a-3 has a thickness of 1.0 mm, roughly covering the outer circumferential tube b. The thickness of the chloroprene layer constituting b-2 was between 2.0 mm and 2.0 mm.This multilayer plastic tube had an inner diameter of 12 mm as a whole and an outer diameter of 25 mm.
Met.

Freon 12 gas, Freon 22 gas, Freon 134 gas to test the performance of this multi-layer plastic tube.
The permeability and flexibility to a-gas were investigated.

The results are shown in Table 1.

1 Nitrile rubber Muniball 1041 100.0 parts: Zinc white manufactured by Nippon Zeon ■ 5.0 parts Stearic acid 1.0 parts 5RF-carbon 50.0 parts: Anti-aging agent N1 manufactured by Asahi Carbon ■ 2,00 parts Nidaiuchi New interest accelerator H
BTS i, 5th division: Shinko Ouchi ■ Production promotion INJ
Z11+4 [IG O, 15th division Ni Ouchi Shinko■
Made of sulfur 1.50 parts (2 chloroprene combination Denka Chloroprene 840 100, 0 parts: Made by Electrochemical ■ 5.0 parts 4.0 parts 40.0 parts: Made by Asahi Carbon ■ 2.00 parts: Made by Ohmukai Shinko ■ 0 .35 parts Zinc oxide magnesia SRF manufactured by Nisan Shin Kagaku ■ - Carbon anti-aging agent PAN Accelerator E1 1 plate In Example 1, the amount of polymethaxylylene adipamide added to 1 to 100 parts of polyethylene terephthalate The same procedure as in Example 1 was carried out except that the amount was changed to 80 parts.

The results are shown in Table 1.

In Example 1, the stretched film forming the inner tube intermediate layer a-2 was wound in the same manner as in Example 1, except that the stretched film was wound an average of 4 times. Ta.

The results are shown in Table 1.

Shakudo Week 1 In Example 1, the following epichlorohydrin rubber compound (1) was used instead of the nitrile rubber compound forming the inner layer a-1 and the outer layer a-3 of the inner circumferential tube sandwiching the stretched film. The same procedure as in Example 1 was carried out except that .

The results are shown in Table 1.

(1) Epichlorohydrin rubber compound Zeclon 1100 100.0 parts Tin stearate manufactured by Nippon Zeon ■ 2.0 parts Red lead 7.0 parts FEF-carbon 40°0 parts Anti-aging agent Tl40G manufactured by Asahi Carbon ■ 1.00 1.20 parts of accelerator El, manufactured by Shinko Buji Ouchi ■: manufactured by Sanshin Kagaku ■ Example 5 Polymethaxylylene having a relative viscosity of 1.6 was used instead of the polymethaxylylene adipamide used in Example 1. - The same procedure as in Example 1 was carried out except that paraxylylene (90/10) adipamide was used.

The results are shown in Table 1.

Except for using metaxylylene-bis(γ-aminopropyl polytetrahydrofuran (9515) adipic acid copolyamide with a relative viscosity of 1.6 in place of the polymethaxylylene adipamide used in AJ1), The same procedure as in Example 1 was carried out.

The results are shown in Table 1.

The inner tube was made of only one layer, and the nitrile rubber compound of Example 1 was used, and the reinforcing thread layer of the outer tube was made of polyester cord (manufactured by Unitika: 1000D//2), and the cover layer was made of polyester cord. Using the same chloroprene composition as in Example 1, a vulcanized rubber tube with an inner circumferential tube having a thickness of 3.0 fi and an outer circumferential tube having a thickness of 2.0 fi was prepared and subjected to a test.

The results are shown in Table 1.

Hidden tray l The inner circumferential tube is made of only one layer, using nylon 6, and the outer circumferential tube is made of only one layer, made of polyetheramide x last? - (PEBAX 5533 ATOC formerly manufactured by HIE), the thickness of the inner tube is 1.0 m,
A plastic tube having a circumferential tube thickness of 4.0 m was prepared and used for testing.

The results are shown in Table 1.

[Brief explanation of the drawing]

Figure 1 schematically shows the cross-sectional structure of an example of the multilayer plastic tube of the present invention as produced in Example 1. Figure 2 schematically shows the cross-sectional structure of a conventional multilayer plastic tube made of nitrile rubber resin. It is a diagram. ...Inner tube...Inner layer of inner tube...Middle layer of inner tube...Outer layer of inner tube...Outer tube...Reinforcing thread waste...Cover layer

Claims (1)

[Claims] 1) A multilayer plastic tube consisting of an inner tube and an outer tube covering the inner tube,
A multilayer plastic tube, wherein at least one layer of the inner peripheral tube is composed of a stretched film of a composition consisting of xylylene group-containing polyamide and polyalkylene terephthalate whose main constituent unit is ethylene terephthalate. 2) A stretched film of a composition in which the inner peripheral tube consists of three layers: an inner layer, an intermediate layer, and an outer layer, and the intermediate layer consists of a xylylene group-containing polyamide and a polyalkylene terephthalate whose main constituent unit is ethylene terephthalate. Claim 1 is characterized in that it consists of
Multilayer plastic tubes as described in Section.