JP2008126614A - Multilayer tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer tube suppressing an occurrence of delamination between respective layers and excellent in durability. <P>SOLUTION: This multilayer tube 10 has a three-layer structure including an inner layer 12 comprising a copolymer fluororesin, an interlayer 14 comprising a blended resin formulated with an ethylene copolymer resin at least containing glycidyl methacrylate and an acid-modified polyolefin resin outside the inner layer 12, and an outer layer 16 comprising a polyurethane resin outside the interlayer 14. As the inner layer 12, for example, a copolymer fluororesin consisting of tetrafluoroethylene, vinylidene fluoride and hexafluoropropylene or the like is used. The occurrence of delamination between respective layers is suppressed by providing the interlayer 14 between the inner layer 12 and the outer layer 16. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multilayer tube having a laminated structure of three or more layers.

  Conventionally, a tube having a two-layer structure is known as a beverage tube.

For example, a two-layer tube in which an outer layer made of polyethylene, ethylene vinyl acetate resin, or the like is provided on an inner layer made of a copolymerized fluororesin is used (see, for example, Patent Document 1).
JP-A-2005-14464

  However, in the two-layer tube described in Patent Document 1, the outer layer made of polyethylene, ethylene vinyl acetate resin or the like is likely to be damaged, the sealing performance between the outer layer and the joint is deteriorated, and liquid leakage may occur. Moreover, in the structure which provided outer layers, such as polyethylene and ethylene vinyl acetate resin, in the inner layer of copolymerization fluororesin, it may lack flexibility.

  As a result of investigations by the present inventors, it was found that a flexible polyurethane resin that is hard to be damaged and is suitable for the outer layer is suitable. However, since polyurethane lacks adhesiveness with a fluororesin, the inner layer and the outer layer are separated. Peeling easily occurs and it is difficult to form two layers.

  In addition, since the fluororesin is expensive and the polyurethane resin is relatively expensive, an increase in the amount of use of both leads to an increase in cost.

  The present invention has been made in order to solve the above-described problems, and provides a multilayer tube that has excellent damage resistance and flexibility while being able to reduce costs while ensuring adhesion between layers. With the goal.

  In order to solve the above-mentioned problem, the multilayer tube according to the invention described in claim 1 contains at least glycidyl methacrylate between an inner layer made of a fluororesin, an outer layer made of a polyurethane resin, and the inner layer and the outer layer. And an intermediate layer made of a blend resin in which an ethylene copolymer resin and an acid-modified polyolefin resin are blended.

  The multilayer tube according to claim 1 uses a fluororesin for the inner layer, and has excellent properties such as chemical resistance, non-adhesiveness, gas barrier property, non-eluting property, odorless property, etc. Is particularly suitable. Further, an intermediate layer made of a blend resin in which an ethylene copolymer resin containing at least glycidyl methacrylate and an acid-modified polyolefin resin are blended is provided outside the inner layer, and an outer layer made of polyurethane resin is provided outside the intermediate layer. The outer layer made of a polyurethane resin has excellent resistance to damage and flexibility, and can suppress a decrease in sealing performance with the joint due to the damage.

  In addition, the inner layer fluororesin and the outer layer urethane resin lack adhesiveness, but by using a blend resin in which an intermediate layer contains an ethylene copolymer resin containing at least glycidyl methacrylate and an acid-modified polyolefin resin, The intermediate layer and the outer layer can be bonded and formed integrally.

  That is, glycidyl methacrylate is used for adhesion to the inner layer fluororesin. In addition, the ethylene copolymer resin containing glycidyl methacrylate is used because polyethylene has a basic polymer structure, and by adding glycidyl methacrylate to it, it can be bonded to various other resins. This is because a polymer is obtained. In addition, as for the mixture ratio of the glycidyl methacrylate with respect to ethylene copolymer resin, 2 to 15 weight% is preferable.

  Then, by using an adhesive glycidyl methacrylate-containing ethylene copolymer resin, it is possible to use a resin that does not adhere to the fluororesin layer alone. That is, by blending with polyethylene, ethylene-vinyl acetate copolymer resin, polypropylene, or an olefin-based elastomer containing these as a main component, these resin layers can be bonded to the inner fluororesin layer.

  Further, the acid-modified polyolefin resin is used for adhesion to the outer layer polyurethane resin. As a result, the occurrence of delamination between the inner layer and the intermediate layer and between the intermediate layer and the outer layer is suppressed, and a multilayer tube having excellent durability can be formed.

  Further, by providing an intermediate layer made of a relatively inexpensive resin with respect to the inner layer fluororesin and the outer layer polyurethane resin, the cost can be reduced as compared with the case where only the fluororesin and polyurethane resin are used.

  A multilayer tube according to a second aspect of the present invention is the multilayer tube according to the first aspect, wherein the intermediate layer comprises an ethylene copolymer resin containing glycidyl methacrylate and an acid-modified polyolefin resin, polyethylene, ethylene-acetic acid. It is characterized in that it is blended by blending with vinyl copolymer resin, polypropylene, or polyolefin resin mainly composed of these.

  According to the invention described in claim 2, the intermediate layer is made of an ethylene copolymer resin containing glycidyl methacrylate and an acid-modified polyolefin resin, polyethylene, ethylene-vinyl acetate copolymer resin, polypropylene, or a main component thereof. Since it is blended with the polyolefin resin to be blended, an inexpensive polyolefin resin can be blended to bond the inner layer, the intermediate layer, and the outer layer. For this reason, compared with the case where an intermediate | middle layer is comprised only with the ethylene copolymer resin and acid-modified polyolefin resin containing glycidyl methacrylate, cost reduction can be aimed at further.

  The multilayer tube according to a third aspect of the present invention is the multilayer tube according to the first or second aspect, wherein the inner layer is a copolymer fluororesin comprising tetrafluoroethylene, vinylidene fluoride, and hexafluoropropylene. It is characterized by being.

  In the invention according to claim 3, the inner layer is made of a copolymerized fluororesin composed of tetrafluoroethylene, vinylidene fluoride, and hexafluoropropylene. The reason for using the copolymerized fluororesin layer composed of these three components is as follows.

  That is, a fluororesin having tetrafluoroethylene as a component exhibits excellent properties such as chemical resistance, non-adhesiveness, gas barrier property, non-elution property, and food hygiene. In addition, vinylidene fluoride has no problem in food hygiene and has little odor adsorption, so it is particularly suitable for use in a beverage tube.

  However, since a tube using vinylidene fluoride has high hardness and low tensile elongation at break, it is difficult to connect to a bamboo shoot-like pipe joint or the like, and vinylidene fluoride may be whitened after being inserted. In addition, when the tube is bent, the bent portion may be whitened.

  Therefore, hexafluoropropylene is used to reduce the hardness and increase the flexibility. As a result, the tensile strength at break increases and the flexural modulus decreases. Further, since the fluorine content in the copolymerized fluororesin layer is increased, surface hydrophobicity, bacteria resistance, contamination resistance, acid resistance, and alkali resistance are improved.

  A multilayer tube according to a fourth aspect of the present invention is the multilayer tube according to any one of the first to third aspects, wherein a reinforcing portion knitted with fibers is provided on the outer periphery of the outer layer, and the reinforcement It is characterized in that a protective layer made of resin is provided on the outside of the portion.

  According to the invention described in claim 4, a multilayer tube excellent in pressure resistance is formed by providing a reinforcing portion knitted with fibers on the outer periphery of the outer layer and providing a protective layer made of resin on the outside of the reinforcing portion. it can.

  Since the multilayer tube according to the present invention is configured as described above, it is possible to suppress the occurrence of delamination between layers, and realize a multilayer tube excellent in durability, damage resistance, flexibility, etc. at low cost. it can.

  Hereinafter, embodiments of the multilayer tube of the present invention will be described with reference to the drawings.

  FIG. 1A is a perspective view showing the multilayer tube 10 according to the first embodiment of the present invention, and FIG. 1B is a cross-sectional view showing the multilayer tube 10.

  This multi-layer tube 10 is made of an ethylene copolymer resin containing glycidyl methacrylate and an acid-modified polyolefin resin, polyethylene, ethylene vinyl acetate, polypropylene, or the main component thereof outside the inner layer 12 made of a copolymerized fluororesin. The tube has a three-layer structure including an intermediate layer 14 made of a blended resin blended with a polyolefin-based resin, and an outer layer 16 made of a polyurethane resin outside the intermediate layer 14.

  As the copolymerized fluororesin constituting the inner layer 12, for example, a copolymerized fluororesin composed of tetrafluoroethylene, vinylidene fluoride, and hexafluoropropylene is used. Copolymer fluororesin has excellent properties such as chemical resistance, non-adhesiveness, gas barrier properties, non-eluting properties, and odorless properties, so that it can absorb odors even when used for beverages. Can be suppressed and tasteless and odorless can be realized. As the inner layer 12, a copolymer resin made of vinylidene fluoride and hexafluoropropylene can also be used.

  The blend resin constituting the intermediate layer 14 is blended with an ethylene copolymer resin containing glycidyl methacrylate and an acid-modified polyolefin resin, and the glycidyl methacrylate makes the adhesiveness with the copolymer fluororesin of the inner layer 12 good, and the acid modification The adhesion between the outer layer 16 and the polyurethane resin is improved by the polyolefin resin. In addition, by blending the glycidyl methacrylate-containing ethylene copolymer resin and the acid-modified polyolefin resin into polyethylene, ethylene-vinyl acetate copolymer resin, polypropylene, or an inexpensive polyolefin-based resin containing these as main components, the cost can be reduced. Is possible. In addition, as for the mixture ratio (weight%) of polyolefin resin, such as glycidyl methacrylate containing ethylene copolymer resin, acid-modified polyolefin resin, and polyethylene, 1: 1: 5-30 are preferable, for example.

  The polyurethane resin constituting the outer layer 16 is classified into an ester type, an ether type, and a polycarbonate type depending on raw material components, and any of them can be used. For foods, ether type is preferred from the viewpoint of mold resistance.

  Such a multilayer tube 10 can manufacture a tube having a three-layer structure in which the inner layer 12, the intermediate layer 14, and the outer layer 16 are integrally laminated by coextrusion molding.

  As the multilayer tube 10, for example, the following can be manufactured.

Inner diameter of multilayer tube 10: 8 mm, outer diameter: 12 mm
Inner layer 12: Copolymer fluororesin comprising tetrafluoroethylene, vinylidene fluoride and hexafluoropropylene (trade name: Dyneon THV, Sumitomo 3M)
Intermediate layer 14: Blend resin in which adhesive resin A and adhesive resin B are blended with polyethylene or ethylene vinyl acetate copolymer resin Adhesive resin A: ethylene copolymer resin containing glycidyl methacrylate (trade name: Bondfast Manufactured by Sumitomo Chemical Co., Ltd.)
Adhesive resin B: acid-modified polyolefin resin (trade name: Admer NF type, manufactured by Mitsui Chemicals, Inc.)
Outer layer 16: Polyurethane resin (trade name: T8195N, manufactured by DIC Polymer Co., Ltd.)
Moreover, since the inner layer 12 is expensive in the fluororesin, it is preferable to reduce the thickness (thickness). The intermediate layer 14 is made thick by blending inexpensive general-purpose resin for cost reduction. The outer layer 16 has a minimum thickness that can provide a protective function in order to reduce the amount of polyurethane resin used. For example, the thickness of the inner layer 12 can be 0.2 mm, the thickness of the intermediate layer 14 can be 1.5 mm, and the thickness of the outer layer 16 can be 0.3 mm.

  Here, an experiment for evaluating the peelability of the multilayer tube of the present invention was conducted.

  As shown in Examples 1 to 5 and Comparative Examples 1 and 2 in Table 1, the multilayer tube 10 in which the material of the intermediate layer 14 is changed is prepared, and the inner layer 12 and the intermediate layer 14, and the intermediate layer 14 and the outer layer 16 are formed. Adhesive strength was evaluated.

  As shown in Table 1, as the intermediate layer 14, a blend of polyethylene resin, adhesive resin A, and adhesive resin B in a ratio of 10: 1: 1 was found in Example 1, polyethylene resin, adhesive resin A, and adhesiveness. Resin B blended at 20: 1: 1 was Example 2, and ethylene-vinyl acetate copolymer resin, adhesive resin A and adhesive resin B were blended at 10: 1: 1 Example 3. A blend of ethylene-vinyl acetate copolymer resin, adhesive resin A, and adhesive resin B in a ratio of 20: 1: 1 is Example 4, and polypropylene resin, adhesive resin A, and adhesive resin B are 20: A blend of 1: 1 was prepared as Example 5.

  On the other hand, as a comparative example, an intermediate layer using only a polyethylene resin (without blending adhesive resin A and adhesive resin B) is comparative example 1, and an intermediate layer using only an ethylene-vinyl acetate copolymer resin (No blend of adhesive resin A and adhesive resin B) was prepared as Comparative Example 2.

  Further, the thicknesses (thicknesses) of the inner layer 12, the intermediate layer 14, and the outer layer 16 and the materials of the inner layer 12 and the outer layer 16 are as shown in Table 2. Moreover, the two-layer tube which provided the layer which consists of ethylene-vinyl acetate copolymer resin on the inner layer which consists of copolymerization fluororesin was the comparative example 3, and the outer layer which consists of polyurethane was provided on the inner layer which consists of copolymerization fluororesin A two-layer tube was prepared as Comparative Example 4.

  The evaluation of adhesive force was performed by rotatably supporting the multi-layer tube 10 having the structure shown in FIG. 1 and pulling the intermediate layer 14 immediately above the inner layer 12 and the outer layer 16 immediately above the intermediate layer 14. And based on the conditions of Comparative Example 1 where peeling occurred, Examples 1 to 5 and Comparative Example 2 were pulled under the same conditions, and the presence or absence of peeling was investigated. The results are shown in Table 1.

  As shown in Table 1, in Examples 1 to 5, peeling between the inner layer 12 and the intermediate layer 14, and the intermediate layer 14 and the outer layer 16 was not observed, but in the comparative examples 1 and 2, the inner layer 12 and the intermediate layer 14, Peeling occurred in both the intermediate layer 14 and the outer layer 16. Moreover, in the comparative example 3 in Table 2, the inner layer which consists of copolymerization fluororesin, and the layer which consists of ethylene-vinyl acetate copolymer resin peeled easily. In Comparative Example 4 in Table 2, the inner layer made of the copolymerized fluororesin and the outer layer made of the polyurethane resin were easily peeled off. Therefore, by blending the adhesive resin A and the adhesive resin B with the intermediate layer 14, the durability compared with the case of using only the polyethylene resin, the ethylene-vinyl acetate copolymer resin, or the case where the intermediate layer of the present invention is not provided. It was confirmed that an excellent multilayer tube was obtained.

  Moreover, as shown in Table 2, the cost of the multilayer tube 10 of Examples 1-5 and Comparative Examples 1-4 was compared. The costs in Table 2 are numerical values showing the costs of the multilayer tubes 10 of the other Examples 2 to 5 and Comparative Examples 1 to 4 when the cost of the multilayer tube 10 of Example 1 is 100. . As a result, the cost of a multilayer tube (polyurethane layer is thick) using copolymer fluorine resin for the inner layer and polyurethane for the outer layer without providing the intermediate layer of Comparative Example 4 is 127, while The cost of the multilayer tube 10 was 100 or less. For this reason, it has confirmed that the multilayer tube 10 of Examples 1-5 was low-cost.

  Next, the multilayer tube which concerns on 2nd Embodiment of this invention is demonstrated based on drawing. In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 2, the multilayer tube 30 is provided with an intermediate layer 14 on the outer side of the inner layer 12, an outer layer 16 on the outer side of the intermediate layer 14, and braided fibers on the outer side of the outer layer 16. A reinforcing portion 32 is provided. Further, a protective layer 34 made of resin is formed outside the reinforcing portion 32.

  As the reinforcement part 32, a polyester fiber, an aramid fiber, etc. can be used, for example. The reinforcing portion 32 is knitted by blade knitting or spiral knitting. As the protective layer 34, a polyurethane resin can be used, and in addition, a vinyl chloride resin, a polyester elastomer, nylon, or the like can be used.

  Such a multilayer tube 30 can be suitably used for piping of a device that requires pressure resistance. When the multi-layer tube 30 may have a low pressure resistance, the reinforcing portion 32 made of fibers and the outer layer 16 can have a structure in which a gap is formed between the reinforcing portion 32 and the protective layer 34. Extrusion coating Thus, the protective layer 34 and the outer layer 16 can be manufactured by hot-melt bonding. Further, in the case where the multilayer tube 30 has a high pressure resistance, and the density of the reinforcing portion 32 is high so that there is no gap between the reinforcing portion 32 and the protective layer 34, a polyurethane adhesive is used to form the protective layer 34. It can be manufactured by adhering to the outer layer 16.

  In addition, it is not limited to the structure of the multilayer tube 30 shown in 2nd Embodiment, You may extrusion-mold or co-extrusion the 4th, 5th ... layer on the outer side of the outer layer 16. FIG. That is, in the multilayer tube, at least the inner layer 12 provided on the innermost side is a copolymerized fluororesin layer according to the present invention, the intermediate layer 14 immediately above it is a layer made of the blended resin according to the present invention, and the outer layer 16 directly above it is the main layer. Any polyurethane resin according to the invention may be used. In addition, the inner layer 12, the intermediate | middle layer 14, and the outer layer 16 can also be integrally formed by blow molding or calendar molding.

(A) is a perspective view which shows the state which cut | disconnected each layer of the multilayer tube which concerns on 1st Embodiment of this invention, (B) is sectional drawing which shows this multilayer tube. It is a perspective view which shows the multilayer tube which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Multilayer tube 12 Inner layer 14 Intermediate layer 16 Outer layer 30 Multilayer tube 32 Reinforcement part 34 Protective layer

Claims (4)

An inner layer made of fluororesin;
An outer layer made of polyurethane resin;
Between the inner layer and the outer layer, an intermediate layer composed of a blend resin in which an ethylene copolymer resin containing at least glycidyl methacrylate and an acid-modified polyolefin resin are blended,
A multilayer tube characterized by comprising:   The intermediate layer was blended by blending an ethylene copolymer resin containing glycidyl methacrylate and an acid-modified polyolefin resin into polyethylene, ethylene-vinyl acetate copolymer resin, polypropylene, or a polyolefin-based resin mainly composed of these. The multilayer tube according to claim 1.   The multilayer tube according to claim 1 or 2, wherein the inner layer is a copolymer fluororesin composed of tetrafluoroethylene, vinylidene fluoride, and hexafluoropropylene. On the outer periphery of the outer layer, a reinforcing part knitted with fibers is provided,
The multilayer tube according to any one of claims 1 to 3, wherein a protective layer made of a resin is provided outside the reinforcing portion.

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