JP2009119609A - Resin laminate tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated resin tube making compatible both high pressure resistance and bending flexibility, and provided further with high flame retardancy. <P>SOLUTION: In this laminated resin tube comprising two layers of at least an inner layer tube and an outer layer tube, the inner layer tube is constituted of a resin excellent in the bending flexibility, for example, a polyurethane resin, and the outer layer tube is constituted of a resin having performance of high breaking stress, for example, a polyamide resin. A thickness of the inner layer tube is 1.0-3.0 mm, and a thickness of the outer layer tube is 0.01-1.5 mm. A halogen-free flame retardant may be added also to a resin material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin tube. More specifically, the present invention relates to a laminated resin tube characterized by having both high pressure resistance and ease of bending. Furthermore, one Embodiment of this invention is related with the laminated resin tube characterized by having a flame retardance.

  Conventionally, resin tubes made from resins having various characteristics have been put to practical use. For example, when a high pressure resistance is required, a resin tube with a high pressure resistance is realized as a design for selecting a high-hardness resin having a high breaking stress in order to withstand a high circumferential stress applied to the resin tube. Resin tubes with high pressure resistance are convenient for transporting gases and liquids, and are used in large quantities in almost every industry, not only in the food and medical fields, but also as piping parts that introduce high-pressure air into air cylinders. is there.

  However, when a resin tube is manufactured from a high-hardness resin, the property (flexible flexibility) of how small the resin tube can be bent is impaired. Resin tubes that are inferior in flexibility are difficult to implement in a space-saving manner because the curvature cannot be increased, and if you try to bend them forcibly, they are fatal for the transportation of gas and liquid, which are the main applications of resin tubes Cause buckling (being bent so that the internal space of the resin tube is closed). Since it is a great advantage of the resin tube that it can be bent relatively freely and can be carried out in a space-saving manner, the lack of flexible flexibility greatly impairs the convenience of the resin tube. Therefore, there has been a demand for a resin tube that achieves a high pressure resistance and also has a good flexibility.

  As technical information suggesting the possibility of solving the above-mentioned problem, Japanese Patent Application Laid-Open No. 2007-119519 discloses that nylon 11 and nylon 12 are blended at a weight ratio of 8: 2 to 2: 8. Nylon resin compositions have been proposed.

  According to the description of paragraphs 0008 to 0015 and 0048 to 0050 of the publication, the nylon resin composition in which nylon 11 and nylon 12 are blended in such a weight ratio improves flexibility and transparency is not impaired. Moreover, it is disclosed that the breaking stress and the yield stress are maintained at substantially the same level as that of the original single resin. This suggests that there is a possibility that both high pressure resistance and good flexible flexibility can be achieved when applied to a resin tube.

  The method of manufacturing a product by blending resin raw materials is highly efficient in mass production. However, it is not easy to produce a large variety of products made from resins with various blending ratios as raw materials. In other words, it is of course most preferable that pressure resistance and flexible flexibility are completely compatible, but in reality, varieties characterized by having high pressure resistance even if the flexibility is somewhat inferior, and vice versa. There are cases where varieties with are absolutely necessary. For this reason, mass production of single varieties is not always easy economically, and it is necessary to produce some kinds of varieties.

  By the way, the manufacture of a tube or the like is often performed by extrusion because it has a feature that a product of stable quality can be manufactured at low cost. In this case, if the type of resin tube to be manufactured is changed, that is, if the type of raw material is changed, the resin staying in the molding machine has to be discarded, resulting in a lot of waste. It will reduce the sex. In addition, in order to use different types of raw material resins, it is necessary to reset conditions such as molding temperature, making it difficult to produce various pressure-resistant and flexible flexible products.

  As another invention for realizing a tube having a desired pressure resistance and flexible flexibility, Japanese Patent Application Laid-Open No. 10-286897 discloses an inner layer tube made of PVdF-HFP copolymer resin by coextrusion molding, and an outer layer tube is formed. A laminated resin tube made of polyurethane resin or polyurethane-based elastomer is described.

  According to the description in paragraphs 0002 and 0004 of the same publication, the past technology in which the resin tube is a laminated tube composed of at least two layers, an inner layer and an outer layer, and the inner layer is made of PVdF resin having a relatively high hardness and the outer layer is made of polyurethane resin or the like. Then, when there was difficulty in flexible flexibility, an invention was disclosed in which flexible flexibility was improved by employing a PVdF-HFP copolymer resin having a low hardness for the inner layer.

  However, there is a problem that it is difficult to obtain a high breakdown voltage by using a resin having a relatively low hardness for both the inner layer and the outer layer. Therefore, in the paragraphs 0005 to 0006 of the same publication, a third layer tube made of a soft synthetic resin is laminated by coextrusion molding with or without a cylindrical reinforcing member on the outer side of the outer layer. There is a description that a high laminated resin tube is obtained.

  However, when the number of layers is increased, the extrusion molding machine becomes larger and complicated, and a special die is required for the co-extrusion molding. In addition, the increase in the types of resins used has the problem of making it difficult to produce a large variety of products for the same reason as described above.

In addition, since the main use of the resin tube is transportation of gas and liquid, it is often used for transportation of air and flammable liquid. Therefore, how hard the resin tube itself does not burn (flame retardancy) is of great concern, but it is often difficult to impart flame retardancy to resin materials with high breaking stress that can produce resin tubes that can withstand high pressures. There are cases. For example, a polyamide resin is an excellent material having a high breaking stress, but it is difficult to impart sufficient flame retardance particularly with a non-halogen flame retardant. However, in order to reduce the influence on the environment at the time of disposal, a resin tube that does not contain a halogen element is socially demanded.
Japanese Patent Laid-Open No. 2007-119519 Japanese Patent Laid-Open No. 10-286897

  Therefore, the problem to be solved by the present invention is to provide a laminated resin tube having both high pressure resistance and flexible flexibility and excellent productivity. Furthermore, this invention makes it the subject which intends to solve providing the laminated resin tube which does not contain a halogen element while providing high flame retardance.

(1) In order to solve the above problems, the present invention provides a laminated resin tube comprising at least two layers of an inner layer tube and an outer layer tube, wherein the inner layer tube is made of a resin having excellent flexibility, and the outer layer tube has a breaking stress. The laminated resin tube is characterized by being made of a resin having high performance.

  The combination in which the inner layer tube is made of a resin with excellent flexibility and the outer layer tube is made of a resin having a high breaking stress is the opposite combination method to the conventional laminated resin tube described above. According to this research, it has been found that a laminated resin tube having unexpectedly superior characteristics can be obtained by using such a combination method.

  In other words, when a laminated resin tube is formed by laminating a resin with excellent flexibility and a resin having high performance at break stress, the resin layer with excellent flexibility and flexibility is usually thick and performance at high break stress. The resin layer having the thickness should be designed to be thin. This is because if the resin layer having a high breaking stress performance is too thick, the laminated resin tube becomes hard as a whole and the flexible flexibility is lost. At this time, if the inner tube is made of a resin layer having a high breaking stress, the inner tube is likely to buckle when the laminated resin tube is bent strongly. This is because the outer layer tube is made of a resin with excellent flexibility and flexibility, so it cannot be expected to support the tough inner layer tube reliably (although compared to the case where the outer layer tube is not provided, it is improved against buckling). But the effect is not enough). Further, when the peel strength between the inner layer tube and the outer layer tube is small, when the laminated resin tube is bent strongly, the inner layer tube and the outer layer tube are peeled off, and the inner layer tube tends to buckle. Therefore, the selection of the resin constituting the inner layer tube and the resin constituting the outer layer tube is limited to combinations that result in extremely high peel strength, and the room for designing various laminated resin tubes is reduced. .

  On the other hand, when the outer layer tube is made of a resin having a high breaking stress, even if the laminated resin tube is strongly bent, the inner layer tube is excellent in flexibility and flexibility, so that it does not easily buckle. Further, even if the outer layer tube is about to buckle, in order for the buckling to occur, the inner layer tube covered with a strong outer layer tube must be crushed, so this does not occur easily. Further, when the outer layer tube is about to buckle, the outer layer tube is pressed against the inner layer tube, and is not peeled off. Therefore, peeling at these interfaces is very unlikely to occur. In other words, since the required peel strength between the inner layer tube and the outer layer tube is relatively small, the types of resin that constitute the inner layer tube and the resin that constitutes the outer layer tube increase, and various laminated resin tubes can be selected. To be able to design.

  Furthermore, it is said that a resin having a high breaking stress performance is generally whitened when bent with a large curvature, increasing the risk of pinholes. And as the layer thickness of the tube is thicker, whitening tends to occur even with a smaller curvature. In other words, the thinner the resin tube, the larger the bending possible. In this sense, it is preferable that the thickness of the resin tube having a high breaking stress is thinner.

  However, if the inner tube of the laminated tube is a thin tube made of a resin having a high breaking stress, the pressure applied to the laminated tube is supported by the inner tube having a small diameter. Even a resin having a high breaking stress has a limit in the pressure that can be supported by a thin resin tube, and as a result, the pressure resistance of the laminated tube is lowered. In order to avoid this, if the thickness of the inner tube made of a resin having a high breaking stress is increased, the flexible flexibility becomes difficult.

  Conversely, when the outer tube of the laminated tube is a thin tube made of a resin having a high breaking stress, which is the structure of the present invention, the pressure applied to the laminated tube is dispersed by the inner tube made of a highly flexible resin. It is supported by an outer layer tube having a large diameter. That is, if the thickness is the same, the stress applied to the outer peripheral tube is reduced, so that a laminated tube with higher pressure resistance can be obtained. Further, since the outer tube made of a resin having a high breaking stress can be made thin if the pressure resistance is the same, the flexible flexibility can be improved. That is, it is possible to realize a laminated resin tube that achieves both high pressure resistance and good flexibility.

  In addition, as a resin material which comprises this invention, it is preferable to select an outer layer tube and an inner layer tube from crystalline resin and an amorphous resin, respectively. In general, crystalline resins have characteristics such as high rigidity and hardness, and amorphous resins have characteristics of excellent flexibility. These are properties suitable for the outer layer tube and inner layer tube of the present invention, respectively. Because there is.

  Moreover, it is preferable that both the resin constituting the inner layer tube and the resin constituting the outer layer tube are thermoplastic resins. This is because by using a thermoplastic resin, a laminated resin tube can be manufactured by coextrusion molding without performing a special adhesion treatment between the inner layer tube and the outer layer tube. Of course, the present invention is not limited to this. For example, the outer layer tube can be formed by coating a thermoplastic resin around the inner layer tube manufactured in advance with a thermosetting resin. However, the high productivity of coextrusion molding has a great effect on reducing the production cost of the resin tube. In addition, since coextrusion molding using a thermoplastic resin can also obtain a strong adhesion between layers, it is more preferable that both the inner layer tube and the outer layer tube are made of a thermoplastic resin as described above. .

  It is also one of the advantages of the present invention that the thickness of each of the inner layer tube and the outer layer tube and the diameter of the laminated tube itself can be freely changed by simply exchanging the coextrusion die. Naturally, by changing these, the pressure resistance and flexible flexibility of the laminated tube can be adjusted to desired specifications. In addition, if the raw material resin is changed, it is necessary to adjust the molding temperature conditions, etc., and it often takes a long time to start production. However, in the present invention, products of various specifications can be made separately without changing the raw material resin. Therefore, it is an invention that is more suitable for high-mix low-volume production.

  As a specific example of the combination of resin materials constituting the present invention, for example, a flame retardant thermoplastic polyurethane can be selected for the inner layer tube, and a flame retardant polyamide can be selected for the outer layer tube. With such selection, good flexible flexibility can be obtained while ensuring excellent flame retardancy. Alternatively, if polyvinyl chloride is selected for the inner layer tube and thermoplastic polyurethane is selected for the outer layer tube, it is possible to obtain good flexibility and flexibility while reducing the cost while ensuring wear resistance by the outer layer tube. It is done.

(2) The present invention is preferably a laminated resin tube, wherein the inner layer tube has a thickness of 1.0 mm to 3.0 mm, and the outer layer tube has a thickness of 0.01 mm to 1.5 mm. .

  By setting it as the thickness range of such an inner layer tube and an outer layer tube, the laminated resin tube suitable for various gas and liquid conveyance can be obtained. That is, it is particularly convenient because it is possible to provide a laminated tube having a high demand, such as a diameter of about 80 mm or less, a pressure resistance of about 0.6 MPa or less, and a minimum bending radius of about 20 mm.

  Further, among the relationship between the thickness of the inner layer tube and the thickness of the outer layer tube, the thickness of the outer layer tube is preferably less than half the thickness of the inner layer tube. This is because by making the outer layer tube thinner than the inner layer tube as described above, a laminated resin tube having a high pressure resistance and excellent flexibility and flexibility can be obtained.

(3) The present invention is preferably a laminated resin tube, wherein the outer layer tube is a polyamide resin.

  Since the polyamide resin has high crystallinity and a large breaking stress, a high pressure resistant laminated resin tube can be obtained by using this as a material for the outer tube. Moreover, since it is excellent in abrasion resistance, the effect that it becomes difficult to generate | occur | produce a damage | wound etc. on the exterior of a laminated resin tube is acquired. Moreover, the polyamide resin is a thermoplastic resin, and can be easily molded into a tube by coextrusion molding.

  In addition, the polyamide resin has a feature of high dimensional stability at the time of molding, and is excellent in this point as a material for the outer layer tube of the laminated resin tube. In the first place, the main use of tubes is for transporting gases and liquids, and they are often used to connect tubes to each other or between tubes and devices using joints. Here, since a leak of gas or liquid is not allowed to occur at the joint between the tube and the joint, it is necessary to realize a reliable seal here. Since sealing is often performed on the outer periphery of the tube, high external dimension accuracy is required. Thus, by forming the outer layer tube with a polyamide resin having high dimensional stability at the time of molding, high external dimensional accuracy can be realized.

(4) The present invention is preferably a laminated resin tube characterized in that the inner layer tube is made of polyurethane resin.

  Polyurethane resin is excellent in flexibility and rubber elasticity, and has extremely excellent properties in terms of flexible flexibility. In addition, it is relatively excellent in oil resistance. Therefore, the material is very suitable for the inner layer tube of the laminated resin tube.

  In addition, when a polyurethane resin and a polyamide resin are co-extruded, they are bonded extremely firmly. Therefore, as described above, if the outer layer resin is made of polyamide, the inner layer resin is made of polyurethane resin, and the laminated resin tube is manufactured by co-extrusion molding, the interface between the inner layer tube and the outer layer tube is extremely strong. Adhere to. Thereby, there is no problem such as peeling at the interface between the inner layer tube and the outer layer tube, and the reliability is high.

  As described above, according to the present invention, an excellent laminated resin tube having both high pressure resistance and flexible flexibility can be obtained.

(5) The present invention is preferably a laminated resin tube characterized in that the inner layer tube and the outer layer tube contain a flame retardant.

  Resin tubes are mainly used for gas and liquid transport, and since these are often air and flammable liquids, it is of great concern how the resin tubes themselves are difficult to burn (flame retardant). Therefore, the laminated resin tube according to the present invention is also preferably a flame retardant laminated resin tube by adding a flame retardant to the resin material constituting the inner layer tube / outer layer tube.

  As flame retardants, various additives such as organic flame retardants containing malocyanurate flame retardants, inorganic flame retardants, bromine flame retardants and chlorine flame retardants, phosphorus flame retardants containing organic phosphate esters, etc. Type flame retardant can be used. It is also possible to use a reactive flame retardant such as a hydrogen group-containing flame retardant or a carboxylic acid-containing flame retardant.

(6) The present invention is preferably a laminated resin tube, wherein the flame retardant is a non-halogen flame retardant.

  In order to reduce the impact on the environment at the time of disposal, products made of resin that do not contain so-called halogen elements such as chlorine are required, and this is achieved by using non-halogen flame retardants. The invention can also be a product that meets such social demands.

  By the way, as already explained, the polyamide resin is excellent in breaking stress and molding stability, but is relatively difficult to impart flame retardancy. Especially, in the case of non-halogen flame retardant, 94 V in the vertical combustion test grade. It is not easy to obtain flame retardancy of −1 or more. However, the inventor of the present invention has found that the flame resistance of the laminated resin tube is almost the same as that of the inner layer tube as a whole if the flame resistance of the inner layer tube is increased even if the flame resistance of the outer layer tube is somewhat low. Found to show. Therefore, the outer layer tube made of a polyamide resin using a non-halogen flame retardant is provided by using a polyurethane resin that can easily obtain a flame resistance of 94V-0 in the vertical combustion test grade for the inner layer tube. Nevertheless, the invention of a laminated resin tube having a flame retardancy as high as 94V-0 in the vertical combustion test grade as a whole has been completed.

  As already described, this configuration provides a laminated resin tube that has both high pressure resistance and good flexible flexibility, and also has high flame retardancy even though it does not contain a halogen element.

  As described above, according to the present invention, it is possible to provide a laminated resin tube that has both high pressure resistance and flexible flexibility, can easily adjust these characteristics according to the application, and is excellent in productivity. In addition, it is possible to provide a laminated resin tube having high flame retardancy although it does not contain a halogen element.

  Hereinafter, the laminated resin tube concerning this invention is demonstrated in detail based on drawing.

  FIG. 1 shows an embodiment of a laminated resin tube according to the present invention. The laminated resin tube (1) is an explanatory diagram of a structure in which an inner tube (2) made of polyurethane resin and an outer tube (3) made of polyamide resin are laminated.

  The laminated resin tube (1) is a tube having an outer diameter of 8 mm and an inner diameter of 4 mm. As an example of this, the inner layer tube (2) has an inner diameter of 4 mm and a thickness of 1.3 mm, and an outer layer tube (3 ) Has a thickness of 0.7 mm. With this configuration, a withstand pressure of 6.5 MPa and a minimum bending radius of 18 mm were obtained.

  Further, the outer diameter is 8 mm and the inner diameter is 4 mm. As another example, the inner layer tube (2) has an inner diameter of 4 mm and a thickness of 1.7 mm, and the outer layer tube (3) positioned outside thereof has a thickness of 0.3 mm. A laminated resin tube was also prototyped. With this configuration, a pressure resistance of 4.5 MPa and a minimum bending radius of 15 mm were obtained.

  Thus, it was proved that the pressure resistance and the flexible flexibility can be adjusted very easily by adjusting the thicknesses of the inner layer tube (2) and the outer layer tube (3).

  The laminated resin tube (1) according to the present invention was manufactured by coextrusion molding. The polyurethane resin and the polyamide resin have good adhesion when co-extrusion molding is performed, and the peel strength at the interface between the inner layer tube (2) and the outer layer tube (3) is extremely high. Therefore, it is unlikely that the inner layer tube (2) and the outer layer tube (3) peel off under normal use conditions.

  Moreover, since the outer layer tube (3) is made of a polyamide resin having high molding shape stability, the outer shape accuracy of the laminated resin tube (1) is extremely high. For this reason, as shown in FIG. 2, when the laminated resin tube (1) is inserted into the joint (4), the outer peripheral seal portion (5) adheres to the outer periphery of the laminated resin tube (1) without any gap, and a reliable seal is obtained. can get. That is, since the outer shape of the laminated resin tube (1) is exactly circular and has almost no irregularities, there is no leakage of the gas / liquid transported when connected to the joint.

  Further, a non-halogen flame retardant is added to the material resin of the inner layer tube (2) and the outer layer tube (3). The inner layer tube (2) made of polyurethane resin has a flame retardancy of 94V-0 in the vertical combustion test grade alone, but the outer layer tube (3) made of polyamide resin has vertical combustion in the case of a non-halogen flame retardant alone. Only the flame resistance of 94V-1 was ensured in the test grade. However, as a whole of the laminated resin tube (1) which is a combination of these, the vertical combustion test grade obtained a flame resistance of 94V-0 which is almost equal to the flame resistance of the inner layer tube (2). That is, although it does not contain a halogen element, a laminated resin tube having high flame retardancy can be realized.

  As described above, the present invention can be widely applied to laminated resin tubes that require both high pressure resistance and flexible flexibility. Furthermore, it is also possible to provide a laminated resin tube having high flame resistance in addition to the above, and its industrial utility value is extremely high.

It is explanatory drawing which showed the implementation method of the laminated resin tube which concerns on this invention. It is explanatory drawing which showed the state which connected the laminated resin tube which concerns on this invention to the joint.

Explanation of symbols

1 Laminated resin tube 2 Inner layer tube 3 Outer layer tube 4 Joint 5 Outer seal

Claims (6)

In a laminated resin tube consisting of at least two layers of an inner layer tube and an outer layer tube,
The inner layer tube is made of resin with excellent flexibility and flexibility.
A laminated resin tube, wherein the outer layer tube is made of a resin having a high breaking stress. The inner tube has a thickness of 1.0 mm to 3.0 mm,
The laminated resin tube according to claim 1, wherein the outer layer tube has a thickness of 0.01 mm to 1.5 mm. The laminated resin tube according to claim 1 or 2, wherein the outer layer tube is made of a polyamide resin. The laminated resin tube according to any one of claims 1 to 3, wherein the inner layer tube is made of polyurethane resin.   The laminated resin tube according to any one of claims 1 to 4, wherein the inner layer tube and the outer layer tube include a flame retardant.   The laminated resin tube according to claim 5, wherein the flame retardant is a non-halogen flame retardant.

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