Laminated tube

Abstract

To provide a laminated tube with an interlayer adhesive property between an inner layer containing polypropylene and an outer layer containing polyamide.SOLUTION: A laminated tube 10 includes an adhesive layer 16 containing acid modification polypropylene between an inner layer 12 containing polypropylene and an outer layer 14 containing polyamide, and a ratio (b / a) of length a of an outer periphery 14a of the outer layer 14 and length b of an outer periphery 16a of the adhesive layer 16 in an axial range of 100 μm is 1.003 or more and 1.050 or less. Also, the polypropylene of a laminated tube 20 including an inner layer 22 containing polypropylene and an outer layer 24 containing polyamide contains acid modification polypropylene. A ratio (b' / a') of length a' of an outer periphery 24a of the outer layer 24 and length b' of an outer periphery 22a of the inner layer 22 in the axial range of 100 μm is 1.003 or more and 1.050 or less.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a laminate tube, and more particularly to a laminate tube suitable as a tube for transporting a coolant in a cooling system of an automobile or the like. [Background technology]

[0002] Coolant transport tubes are used to transport coolants in the cooling systems of gasoline-powered vehicles and electric vehicles. Polyamide resins are often used for coolant transport tubes because of their heat resistance. Polypropylene resins are also being considered because of their cost-effectiveness. Furthermore, laminated tubes made of polyamide resins and polypropylene resins are also being considered. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2008-507436 [Patent Document 2] JP 2012-082885 A Summary of the Invention [Problem to be solved by the invention]

[0004] A laminated tube of polypropylene resin and polyamide resin has poor adhesion between the resins. Patent Document 2 studies the use of acid-modified polypropylene for the polypropylene resin to improve adhesion with the polyamide resin. However, there is still room for improvement in interlayer adhesion.

[0005] An object of the present invention is to provide a laminate tube having excellent interlayer adhesion between an inner layer containing polypropylene and an outer layer containing polyamide. [Means for solving the problem]

[0006] The laminated tube of the present invention has an inner layer containing polypropylene and an outer layer containing polyamide, and an adhesive layer containing acid-modified polypropylene is disposed between the inner layer and the outer layer, and the ratio (b / a) of the length a of the outer peripheral surface of the outer layer to the length b of the outer peripheral surface of the adhesive layer within an axial range of 100 μm is 1.003 or more and 1.050 or less.

[0007] Another laminate tube according to the present invention is a laminate tube having an inner layer containing polypropylene and an outer layer containing polyamide, wherein the polypropylene contains acid-modified polypropylene, and the ratio (b' / a') of the length a' of the outer peripheral surface of the outer layer to the length b' of the outer peripheral surface of the inner layer within an axial range of 100 μm is 1.003 or more and 1.050 or less.

[0008] In the laminate tube according to the present invention, the adhesive layer may be made of a resin composition containing organic polymer particles in an acid-modified polypropylene matrix. In another laminate tube according to the present invention, the inner layer may be made of a resin composition containing organic polymer particles in an acid-modified polypropylene matrix.

[0009] The organic polymer particles may be composed of an ethylene-propylene copolymer or an ethylene polymer. The content of the organic polymer particles may be 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the acid-modified polypropylene matrix. The average particle size of the organic polymer particles may be 0.1 μm or more and 10 μm or less.

[0010] The amine value of the polyamide is preferably 15 mmol / kg or more and 100 mmol / kg or less. In the laminate tube according to the present invention, the adhesive strength at the interface between the adhesive layer and the outer layer is preferably 30 N / cm or more. In another laminate tube according to the present invention, the adhesive strength at the interface between the inner layer and the outer layer is preferably 30 N / cm or more.

[0011] The laminate tube according to the present invention and the other laminate tube according to the present invention may be used as a coolant transport tube for a vehicle.

[0012] (1) The laminate tube of the present invention has an inner layer containing polypropylene and an outer layer containing polyamide, and has an adhesive layer containing acid-modified polypropylene between the inner layer and the outer layer, and the ratio (b / a) of the length a of the outer peripheral surface of the outer layer to the length b of the outer peripheral surface of the adhesive layer within an axial range of 100 μm is 1.003 or more and 1.050 or less.

[0013] (2) Another laminate tube according to the present invention is a laminate tube having an inner layer containing polypropylene and an outer layer containing polyamide, wherein the polypropylene contains acid-modified polypropylene, and the ratio (b' / a') of the length a' of the outer peripheral surface of the outer layer to the length b' of the outer peripheral surface of the inner layer within an axial range of 100 μm is 1.003 or more and 1.050 or less.

[0014] (3) In the above (1), the adhesive layer may be made of a resin composition containing organic polymer particles in a matrix of acid-modified polypropylene.

[0015] (4) In the above (2), the inner layer may be made of a resin composition containing organic polymer particles in a matrix of acid-modified polypropylene.

[0016] (5) In the above (3) or (4), the organic polymer particles may be composed of an ethylene-propylene copolymer or an ethylene polymer.

[0017] (6) In any one of the above (3) to (5), the content of the organic polymer particles may be 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the acid-modified polypropylene matrix.

[0018] (7) In any one of the above (3) to (6), the average particle size of the organic polymer particles may be from 0.1 μm to 10 μm.

[0019] (8) In any one of the above (1) to (7), the amine value of the polyamide may be 15 mmol / kg or more and 100 mmol / kg or less.

[0020] (9) In the above (8) which is dependent on the above (1), the adhesive strength at the interface between the adhesive layer and the outer layer may be 30 N / cm or more.

[0021] (10) In the above (8) which is subordinate to the above (2), the adhesive strength at the interface between the inner layer and the outer layer may be 30 N / cm or more.

[0022] (11) In any one of the above (1) to (10), the present invention may be used for a vehicle coolant transport tube. Effect of the Invention

[0023] The laminate tube according to the present invention has an inner layer containing polypropylene and an outer layer containing polyamide, and has an adhesive layer containing acid-modified polypropylene between the inner layer and the outer layer, and the ratio (b / a) of the length a of the outer peripheral surface of the outer layer to the length b of the outer peripheral surface of the adhesive layer in an axial range of 100 μm is 1.003 or more and 1.050 or less. The length b of the outer peripheral surface of the adhesive layer bonding the inner layer containing polypropylene and the outer layer containing polyamide is longer than the length a of the outer peripheral surface of the outer layer, so that the contact area between the inner peripheral surface of the outer layer and the outer peripheral surface of the adhesive layer is large, resulting in excellent interlayer adhesion between the adhesive layer and the outer layer. In addition, since both the adhesive layer and the inner layer are layers containing polypropylene, the interlayer adhesion between the adhesive layer and the inner layer is also excellent. As a result, the interlayer adhesion between the inner layer containing polypropylene and the outer layer containing polyamide is excellent.

[0024] Another laminate tube according to the present invention is a laminate tube having an inner layer containing polypropylene and an outer layer containing polyamide, wherein the polypropylene contains acid-modified polypropylene, and the ratio (b' / a') of the length a' of the outer peripheral surface of the outer layer to the length b' of the outer peripheral surface of the inner layer within an axial range of 100 μm is 1.003 or more and 1.050 or less. Since the length b' of the outer peripheral surface of the inner layer, which is the adhesive interface between the inner layer containing polypropylene and the outer layer containing polyamide, is longer than the length a' of the outer peripheral surface of the outer layer, the contact area between the inner peripheral surface of the outer layer and the outer peripheral surface of the inner layer is increased, resulting in excellent interlayer adhesion between the inner layer containing polypropylene and the outer layer containing polyamide.

[0025] In the laminated tube according to the present invention, when the adhesive layer is made of a resin composition containing organic polymer particles in an acid-modified polypropylene matrix, the organic polymer particles tend to affect the formation of an uneven shape on the outer peripheral surface of the adhesive layer, making it easier to make the length b of the outer peripheral surface of the adhesive layer longer than the length a of the outer peripheral surface of the outer layer. In addition, the tear strength in the length direction of the acid-modified polypropylene matrix can be improved. This can further improve the interlayer adhesion between the inner layer containing polypropylene and the outer layer containing polyamide.

[0026] In another laminate tube according to the present invention, when the inner layer is made of a resin composition containing organic polymer particles in an acid-modified polypropylene matrix, the organic polymer particles tend to form an uneven shape on the outer peripheral surface of the inner layer, and the length b' of the outer peripheral surface of the inner layer tends to be longer than the length a' of the outer peripheral surface of the outer layer. In addition, the tear strength in the length direction of the acid-modified polypropylene matrix can be improved. This can further improve the interlayer adhesion between the inner layer containing polypropylene and the outer layer containing polyamide.

[0027] Here, when the organic polymer particles are composed of an ethylene-propylene copolymer or an ethylene polymer, it is easy to form an uneven shape on the outer peripheral surface of the adhesive layer or the inner layer, and the effect of improving the tear strength in the longitudinal direction of the acid-modified polypropylene matrix is ​​excellent.

[0028] Furthermore, when the content of the organic polymer particles is 5 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the acid-modified polypropylene matrix, an excellent balance is achieved between the effect of improving the adhesion between the adhesive layer or the inner layer and the outer layer by forming an uneven shape on the outer peripheral surface of the adhesive layer or the inner layer to increase the contact area, and the effect of improving the adhesion by the acid-modified polypropylene and polyamide.

[0029] When the average particle size of the organic polymer particles is 0.1 μm or more and 10 μm or less, an excellent balance is achieved between the effect of improving the adhesion between the adhesive layer or the inner layer and the outer layer by forming an uneven shape on the outer peripheral surface of the adhesive layer or the inner layer to increase the contact area, and the effect of improving the adhesion by the acid-modified polypropylene and polyamide.

[0030] When the amine value of the polyamide is 15 mmol / kg or more and 100 mmol / kg or less, the adhesion between the acid-modified polypropylene and the polyamide is excellent, thereby improving the adhesion between the adhesive layer and the outer layer or the adhesion between the inner layer and the outer layer.

[0031] In the laminate tube according to the present invention, when the adhesive strength at the interface between the adhesive layer and the outer layer is 30 N / cm or more, the adhesiveness between the adhesive layer and the outer layer is excellent. In another laminate tube according to the present invention, when the adhesive strength at the interface between the inner layer and the outer layer is 30 N / cm or more, the adhesiveness between the inner layer and the outer layer is excellent.

[0032] The laminate tube according to the present invention and the other laminate tube according to the present invention are suitable for use as a coolant transport tube for vehicles. [Brief description of the drawings]

[0033] [Figure 1] 1 is a configuration diagram showing a laminate tube according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view of the laminated tube shown in FIG. 1 in a range of 100 μm in the axial direction. [Diagram 3] FIG. 4 is a configuration diagram showing a laminated tube according to another embodiment of the present invention. [Figure 4] 4 is a cross-sectional view of the laminated tube shown in FIG. 3 in a range of 100 μm in the axial direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] The laminate tube according to the present invention will be described in detail below. Fig. 1 is a structural diagram of a laminate tube according to one embodiment of the present invention. Fig. 2 is a cross-sectional view of the laminate tube shown in Fig. 1 in a range of 100 µm in the axial direction.

[0035] As shown in FIG. 1, a laminate tube 10 according to an embodiment of the present invention has an inner layer 12, an outer layer 14, and an adhesive layer 16. The inner layer 12, the outer layer 14, and the adhesive layer 16 are each configured in a tubular shape. The laminate tube 10 has a three-layer laminate structure in which the inner layer 12, the adhesive layer 16, and the outer layer 14 are laminated in a tubular shape, in that order from the inside. The adhesive layer 16 is disposed between the inner layer 12 and the outer layer 14 as a layer that bonds the inner layer 12 and the outer layer 14. The adhesive layer 16 is disposed on the outer peripheral surface of the inner layer 12 in contact with the inner layer 12. The outer layer 14 is disposed on the outer peripheral surface of the adhesive layer 16 in contact with the adhesive layer 16.

[0036] The laminated tube 10 has an inner layer 12 containing polypropylene and an outer layer 14 containing polyamide. The outer layer 14 containing polyamide ensures strength and heat resistance. The inner layer 12 containing polypropylene prevents the fluid flowing through the laminated tube 10 from contacting the outer layer 14 containing polyamide, thereby preventing a decrease in strength due to hydrolysis. Since the inner layer 12 containing polypropylene is protected by the outer layer 14 containing polyamide against the internal pressure of the fluid flowing through the laminated tube 10, the interlayer adhesion between the inner layer 12 containing polypropylene and the outer layer 14 containing polyamide is important. Since polypropylene and polyamide generally have low adhesion, the laminated tube 10 has an adhesive layer 16 arranged as a layer that bonds the inner layer 12 and the outer layer 14. The adhesive layer 16 is a layer containing acid-modified polypropylene.

[0037] 2, 14a is the outer peripheral surface of the outer layer 14. 16a is the outer peripheral surface of the adhesive layer 16. 16b is the inner peripheral surface of the adhesive layer 16. The axial direction of the laminate tube 10 is the direction in which the laminate tube 10 extends, which is the X direction in FIGS.

[0038] As shown in Fig. 2, in the laminate tube 10, the ratio (b / a) of the length a of the outer peripheral surface 14a of the outer layer 14 to the length b of the outer peripheral surface 16a of the adhesive layer 16 within a range of 100 µm in the axial direction is 1.003 or more and 1.050 or less. The outer peripheral surface 14a of the outer layer 14 is the portion that comes into contact with the molding die during extrusion molding, and is the portion where the generation of undulations during extrusion molding is suppressed. Therefore, it can be expressed as a length that is free of undulations and close to a straight line. The ratio (b / a) of the length b of the outer peripheral surface 16a of the adhesive layer 16 to the length a of the outer peripheral surface 14a exceeds 1. Since the length b of the outer surface 16a of the adhesive layer 16 that bonds the inner layer 12 containing polypropylene and the outer layer 14 containing polyamide is longer than the length a of the outer surface 14a of the outer layer 14, the contact area between the inner surface of the outer layer 14 and the outer surface 16a of the adhesive layer 16 is increased, resulting in excellent interlayer adhesion between the adhesive layer 16 and the outer layer 14.

[0039] In the present invention, the waviness of the outer peripheral surface 16a of the adhesive layer 16 is intentionally increased, and the contact area between the outer peripheral surface 16a of the adhesive layer 16 and the inner peripheral surface of the outer layer 14 is increased, thereby improving the interlayer adhesion between the adhesive layer 16 and the outer layer 14. If the ratio (b / a) is less than 1.003, the improvement in adhesion due to the increased contact area is insufficient. If the ratio (b / a) is more than 1.050, the waviness of the outer peripheral surface 16a of the adhesive layer 16 becomes too large, and the adhesion decreases. Methods for increasing the waviness of the outer peripheral surface 16a of the adhesive layer 16 include changing the extrusion temperature of each layer during extrusion molding to increase the viscosity difference between the layers to form waviness larger than the unavoidable waviness that occurs naturally, and blending organic polymer particles 18 into the material of the adhesive layer 16 to generate convex or concave portions due to the organic polymer particles 18 on the outer peripheral surface 16a of the adhesive layer 16.

[0040] From the viewpoint of improving adhesion due to an increase in the contact area, the ratio (b / a) is preferably 1.005 or more, more preferably 1.007 or more. Also, from the viewpoint of suppressing a decrease in adhesion due to an increase in waviness, the ratio (b / a) is preferably 1.040 or less, more preferably 1.030 or less.

[0041] The length a of the outer peripheral surface 14a of the outer layer 14 and the length b of the outer peripheral surface 16a of the adhesive layer 16 can be determined by photographing the cross section observed by cutting the laminated tube 10 in half in the axial direction using a scanning electron microscope (SEM) at a magnification of 5000 times, and connecting ten of the images.

[0042] The inner layer 12 is composed of a composition containing polypropylene. The inner layer 12 contains polypropylene as a main component. The main component is 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0043] Examples of the polypropylene of the inner layer 12 include propylene-based polymers such as propylene homopolymers, propylene-α-olefin random copolymers, and propylene-α-olefin block copolymers. Of these, propylene-α-olefin block copolymers are preferred. Examples of the α-olefins include ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. Of these, ethylene, 1-butene, and 1-hexene are preferred, and ethylene is particularly preferred.

[0044] The propylene-α-olefin block copolymer is not limited to a block copolymer having at least a block of continuous propylene monomers and a block of continuous α-olefin monomers, but also includes, for example, an alloy (mixture) having an island-in-sea structure in which a polypropylene component such as a propylene homopolymer is in the sea phase and a polyethylene component and / or an ethylene-based rubber component is in the island phase. Examples of the polyethylene component include ethylene-based copolymers such as ethylene homopolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, and copolymers of ethylene and α-olefins (ethylene-propylene copolymers, ethylene-butene copolymers, and ethylene-octene copolymers). Examples of the ethylene-based rubber component include ethylene-propylene-diene terpolymers (EPDM), ethylene-propylene copolymers (EPR), ethylene-butene copolymers (EBR), and ethylene-octene copolymers (EOR). The content of the polyethylene component and / or the ethylene-based rubber component in the entire alloy (mixture) is, for example, 1 to 49 mass %, or 2.5 to 20 mass %.

[0045] In addition to polypropylene, the composition constituting the inner layer 12 may contain, as necessary, stabilizers, lubricants, pigments, dyes, antistatic agents, plasticizers, antioxidants, etc. Furthermore, the composition constituting the inner layer 12 may be formed by melt-kneading these materials and pelletizing them, as necessary.

[0046] The outer layer 14 is composed of a composition containing polyamide. The outer layer 14 contains polyamide as a main component. The main component is 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. The polyamide may be an aliphatic polyamide or an aromatic polyamide. As the polyamide, an aliphatic polyamide is more preferable from the viewpoint of affinity with polypropylene.

[0047] From the viewpoint of improving adhesion to acid-modified polypropylene, the polyamide preferably has an amine value of 15 mmol / kg or more. More preferably, it is 20 mmol / kg or more, and even more preferably, it is 25 mmol / kg or more. On the other hand, from the viewpoint of excellent extrusion moldability, the amine value is preferably 100 mmol / kg or less. More preferably, it is 80 mmol / kg or less, and even more preferably, it is 60 mmol / kg or less. The amine value of polyamide indicates the number of mmoles of amine contained in 1 kg of solid content of polyamide. The outer layer 14 may contain 50 mass% or more of polyamide exhibiting a specific amine value. It is preferably 70 mass% or more, more preferably 90 mass% or more, and even more preferably 95 mass% or more.

[0048] Examples of polyamides exhibiting a specific amine value include aliphatic polyamides such as polyamide 46 (PA46), polyamide 410 (PA410), polyamide 6 (PA6), polyamide 66 (PA66), polyamide 610 (PA610), polyamide 612 (PA612), polyamide 11 (PA11), polyamide 12 (PA12), and polyamide 1010 (PA1010), and aromatic polyamides such as polyamide 6T (PA6T), polyamide 9T (PA9T), and polyamide 10T (PA10T). As the polyamide of the outer layer 14, one of these may be used alone, or two or more of them may be used in combination.

[0049] From the viewpoint of heat resistance, the polyamide preferably has a melting point of 160° C. or higher, and more preferably 170° C. or higher. On the other hand, from the viewpoint of ensuring adhesiveness, the polyamide preferably has a melting point of 280° C. or lower, and more preferably 270° C. or lower.

[0050] In addition to polyamide, the composition constituting the outer layer 14 may contain, as necessary, stabilizers, lubricants, pigments, dyes, antistatic agents, plasticizers, antioxidants, etc. Furthermore, the composition constituting the outer layer 14 may be prepared by melt-kneading these materials and pelletizing them, as necessary.

[0051] The adhesive layer 16 contains acid-modified polypropylene as a matrix polymer. This provides excellent adhesion to the outer layer 14 containing polyamide. The adhesive layer 16 may be composed of a resin composition containing acid-modified polypropylene as a matrix polymer and organic polymer particles 18 in the matrix of the acid-modified polypropylene. The matrix polymer is the main component in the adhesive layer 16. The main component is 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The polymer component in the adhesive layer 16 may be composed of only acid-modified polypropylene, or may contain a polymer component such as polypropylene that is not modified with acid. In this case, the acid-modified polypropylene of the polymer components in the adhesive layer 16 may be preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The adhesive layer 16 does not necessarily have to contain organic polymer particles 18.

[0052] The acid in the acid-modified polypropylene includes unsaturated carboxylic acids and their derivatives. The unsaturated carboxylic acids include maleic acid, fumaric acid, acrylic acid, and methacrylic acid. The unsaturated carboxylic acid derivatives include acid anhydrides, esters, amides, imides, and metal salts. Among these, maleic acid and maleic anhydride are particularly preferred from the viewpoint of reactivity with polyamide.

[0053] The amount of acid modification in the acid-modified polypropylene is preferably 0.05% by mass or more from the viewpoint of improving adhesion to the outer layer 14, and more preferably 0.1% by mass or more. On the other hand, from the viewpoint of ensuring heat resistance, the amount of acid modification is preferably 7% by mass or less, and more preferably 5% by mass or less. Furthermore, from the viewpoint of ensuring heat resistance, the acid-modified polypropylene preferably has a melting point of 130° C. or more, and more preferably 140° C. or more. On the other hand, from the viewpoint of ensuring adhesiveness, the melting point is preferably 180° C. or less, and more preferably 170° C. or less.

[0054] The organic polymer particles 18 are disposed in the matrix polymer (acid-modified polypropylene) of the adhesive layer 16. By including the organic polymer particles 18, as shown in FIG. 2, it becomes easy to form convexities and concaves (uneven shapes) on the outer peripheral surface 16a and inner peripheral surface 16b of the adhesive layer 16. This makes it easy to make the length b of the outer peripheral surface 16a of the adhesive layer 16 longer than the length a of the outer peripheral surface 14a of the outer layer 14. In addition, in the laminated tube 10 that is extrusion molded, the matrix polymer (acid-modified polypropylene) of the adhesive layer 16 that is oriented in the longitudinal direction is easily torn into fibers, and the tear strength in the longitudinal direction is weakened. The organic polymer particles 18 disposed in the matrix polymer of the adhesive layer 16 become an obstacle to the tear force in the longitudinal direction, thereby improving the tear strength in the longitudinal direction.

[0055] Examples of the organic polymer particles 18 include organic polymer particles 18 such as rubber and resin. Examples of the rubber material include ethylene-propylene copolymer, ethylene-octene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, and ethyl acrylate. Examples of the resin include polyethylene. As the organic polymer particles 18, one of these may be used alone, or two or more may be used in combination. Among these, ethylene-propylene copolymer and polyethylene are more preferable from the viewpoints of excellent compatibility with the matrix polymer, ease of forming an uneven shape on the outer peripheral surface 16a of the adhesive layer 16, and excellent effect of improving the tear strength in the length direction of the matrix of the acid-modified polypropylene.

[0056] The organic polymer particles 18 may be pre-granulated and then added to the matrix polymer, or an ungranulated organic polymer may be melt-kneaded with the matrix polymer under specific conditions to form pellets, and then melt-extruded under specific conditions to contain the organic polymer particles 18 in the acid-modified polypropylene matrix.

[0057] The content of the organic polymer particles 18 is preferably 5 parts by mass or more relative to 100 parts by mass of the acid-modified polypropylene matrix from the viewpoints of excellent effect of improving the adhesion between the adhesive layer 16 and the outer layer 14 by forming an uneven shape on the outer peripheral surface 16a of the adhesive layer 16 to improve the contact area, and excellent effect of improving the tear strength in the length direction of the acid-modified polypropylene matrix. More preferably, it is 10 parts by mass or more. On the other hand, from the viewpoint of excellent effect of improving the adhesion by the acid-modified polypropylene and polyamide, it is preferably 20 parts by mass or less relative to 100 parts by mass of the acid-modified polypropylene matrix. More preferably, it is 15 parts by mass or less. The content of the organic polymer particles 18 in the adhesive layer 16 can be obtained by taking an image at a magnification of 1000 times with a scanning electron microscope (SEM) and binarizing it.

[0058] The average particle size of the organic polymer particles 18 is preferably 0.1 μm or more from the viewpoint of excellent effect of improving the adhesion between the adhesive layer 16 and the outer layer 14 by forming an uneven shape on the outer peripheral surface 16a of the adhesive layer 16 to improve the contact area, and excellent effect of improving the tear strength in the length direction of the matrix of the acid-modified polypropylene. More preferably, it is 0.3 μm or more. On the other hand, from the viewpoint of excellent effect of improving the adhesion by the acid-modified polypropylene and polyamide, the above average particle size is preferably 10 μm or less. More preferably, it is 5 μm or less, and further preferably, it is 3 μm or less. The average particle size of the organic polymer particles 18 can be expressed by taking a cross section of the adhesive layer 16 at a magnification of 5000 times with a scanning electron microscope (SEM), measuring the particle sizes of any 10 organic polymer particles 18 observed, and averaging the measured particle sizes.

[0059] In addition to the acid-modified polypropylene, the composition constituting the adhesive layer 16 may contain stabilizers, lubricants, pigments, dyes, antistatic agents, plasticizers, antioxidants, etc., as necessary. Furthermore, the composition constituting the adhesive layer 16 may be prepared by melt-kneading these materials and pelletizing them, as necessary.

[0060] As shown in FIG. 2, the outer peripheral surface 16a and the inner peripheral surface 16b of the adhesive layer 16 may have one or more convex portions or concave portions. The adhesive layer 16 and the outer layer 14, and the adhesive layer 16 and the inner layer 12 may have improved adhesion due to the anchor effect. The height of the convex portion or the depth of the concave portion may be 0.1 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less. The adhesive layer 16 and the outer layer 14 may have improved adhesion due to the anchor effect. The convex portion and the concave portion are relative terms, and may be expressed as either one.

[0061] From the viewpoint of the anchoring effect, the number of the convex or concave portions is preferably 2 or more per 100 μm in the length direction at any position. Also, from the viewpoint of ensuring the adhesiveness of the acid-modified polypropylene, the number of the convex or concave portions is preferably 100 or less per 100 μm in the length direction at any position. Also, from the viewpoint of ensuring the adhesiveness of the acid-modified polypropylene, the number of the convex or concave portions is preferably 100 or less per 100 μm in the circumferential direction at any position. The number of the convex or concave portions can be calculated by photographing a cross section of the adhesive layer 16 in a predetermined direction at a magnification of 5000 times with a scanning electron microscope (SEM) and connecting 10 of the images.

[0062] The above-mentioned convex or concave portions can be formed due to the blending of the organic polymer particles 18, or by changing the extrusion temperature of each layer to increase the difference in viscosity between the layers.

[0063] The tear strength in the longitudinal direction of the adhesive layer 16 is preferably 20 N / mm or more, more preferably 25 N / mm or more, and even more preferably 30 N / mm or more. For example, the adhesive layer 16 can satisfy the above tear strength by being composed of a resin composition containing organic polymer particles 18 in an acid-modified polypropylene matrix. The above tear strength can be measured by extruding a film having a thickness of 0.3 mm, and using a trouser-type test piece in accordance with JIS K 6252, at room temperature and at a tensile speed of 100 mm / min.

[0064] The adhesive strength at the interface between the adhesive layer 16 and the outer layer 14 is preferably 30 N / cm or more. More preferably, it is 35 N / cm or more, and even more preferably, it is 40 N / cm or more. For example, the adhesive strength at the interface can be satisfied by adjusting the amount of acid modification of the acid-modified polypropylene, the amine value of the polyamide, the ratio (b / a) of the length a of the outer surface 14a of the outer layer 14 to the length b of the outer surface 16a of the adhesive layer 16, and the amount of the organic polymer particles 18. The adhesive strength can be measured by preparing a 10 mm rectangular test piece from the laminated tube 10 divided in half in the axial direction, peeling off the end of the test piece with nippers or the like, gripping the peeled part, and performing interlayer peeling with a tensile tester. The tensile speed is 25 mm / min, and the average adhesive strength (N / cm) when the peel strength remains stable for 30 seconds is taken as the adhesive strength.

[0065] The laminate tube 10 can be manufactured as follows. First, the composition constituting the inner layer 12, the composition constituting the outer layer 14, and the composition constituting the adhesive layer 16 are each prepared. Each composition is pelletized as necessary. Next, using an extruder, each composition is melt extruded (co-extruded) into a tubular shape on a mandrel. This makes it possible to obtain the laminate tube 10 having a three-layer laminate structure in which, from the inside, the inner layer 12, the adhesive layer 16, and the outer layer 14 are laminated in a tubular shape.

[0066] Each layer is preferably extruded at a temperature of 200 to 350°C (preferably 220 to 280°C) and a take-up speed of 1 to 15 m / min (preferably 3 to 5 m / min). Here, when melt extrusion (co-extrusion) is performed at a temperature 20 to 100°C higher (preferably 20 to 80°C higher) than the melting point of the polyamide of the outer layer 14, the organic polymer particles 18 in the adhesive layer 16 tend to be unevenly distributed near the interface between the adhesive layer 16 and the outer layer 14 or near the interface between the adhesive layer 16 and the inner layer 12. This increases the waviness of the outer peripheral surface 16a of the adhesive layer 16 due to the organic polymer particles 18, and increases the contact area between the inner peripheral surface of the outer layer 14 and the outer peripheral surface 16a of the adhesive layer 16, thereby providing excellent interlayer adhesion between the adhesive layer 16 and the outer layer 14.

[0067] The laminated tube 10 having the above configuration has an adhesive layer 16 containing acid-modified polypropylene between the inner layer 12 containing polypropylene and the outer layer 14 containing polyamide, and the ratio (b / a) of the length a of the outer peripheral surface 14a of the outer layer 14 to the length b of the outer peripheral surface 16a of the adhesive layer 16 within an axial range of 100 μm is 1.003 or more and 1.050 or less. The length b of the outer peripheral surface 16a of the adhesive layer 16 bonding the inner layer 12 containing polypropylene and the outer layer 14 containing polyamide is longer than the length a of the outer peripheral surface 14a of the outer layer 14, so that the contact area between the inner surface of the outer layer 14 and the outer peripheral surface 16a of the adhesive layer 16 is large, and therefore the interlayer adhesion between the adhesive layer 16 and the outer layer 14 is excellent. In addition, since the adhesive layer 16 contains acid-modified polypropylene, the adhesion to the outer layer 14 containing polyamide is further improved. In addition, since both the adhesive layer 16 and the inner layer 12 contain polypropylene, the adhesive layer 16 and the inner layer 12 also have excellent interlayer adhesion. This results in excellent interlayer adhesion between the inner layer 12 containing polypropylene and the outer layer 14 containing polyamide.

[0068] The laminated tube 10 is used as a radiator hose, a heater hose, an air conditioner hose, or a cooling tube for a battery pack for an electric vehicle or a fuel cell vehicle. The laminated tube 10 can be used not only for automobiles, but also for other transport machines (industrial transport vehicles such as airplanes, forklifts, excavators, and cranes, railroad cars, etc.).

[0069] The laminated tube 10 has an inner diameter of preferably 2 to 40 mm, more preferably 4 to 35 mm. The thickness of the inner layer 12 is preferably 0.1 to 1.9 mm, more preferably 0.2 to 1.8 mm. The thickness of the outer layer 14 is preferably 0.1 to 1.9 mm, more preferably 0.2 to 1.8 mm. The thickness of the adhesive layer 16 is preferably 0.05 to 0.5 mm, more preferably 0.05 to 0.3 mm.

[0070] Here, when the laminated tube 10 is used for transporting vehicle coolant, the inner layer 12 containing polypropylene may be required to have a certain heat resistance. In this case, it is considered to blend an antioxidant into the composition containing polypropylene of the inner layer 12. When an antioxidant is blended into the material of the vehicle coolant transport tube, components derived from the antioxidant tend to be extracted (eluted) into the coolant, which may cause clogging of the filter in the vehicle cooling system, or the extracted components may increase the conductivity of the coolant, causing a short circuit or electric leakage. Therefore, excellent heat resistance and extraction resistance are required.

[0071] When an antioxidant is used, heat resistance and extraction resistance are in conflict with each other. In other words, from the viewpoint of improving heat resistance, it is required to increase the amount of antioxidant blended, but if the amount of antioxidant blended is increased, it becomes difficult to suppress the amount of components derived from the antioxidant extracted into the coolant, and extraction resistance cannot be guaranteed. In contrast, if a specific polypropylene and a specific antioxidant are used in combination and the content ratio of both is within a specific range, heat resistance and extraction resistance are excellent.

[0072] The polypropylene of the inner layer 12 preferably has a melt flow rate (MFR) of 0.2 g / 10 min or more and less than 2.0 g / 10 min. Also, it preferably has a melting point of 145° C. or more. This provides excellent extraction resistance and heat resistance. With the MFR of less than 2.0 g / 10 min and the melting point of 145° C. or more, the compatibility of the polypropylene with the antioxidant is improved and the amount of extraction into the cooling liquid is reduced, so that a high degree of heat resistance and extraction resistance can be achieved at the same time.

[0073] From the above viewpoints, the MFR of polypropylene is more preferably 1.8 g / 10 min or less, even more preferably 1.6 g / 10 min or less, and particularly preferably 1.5 g / 10 min or less. On the other hand, from the viewpoints of ensuring flowability, the MFR of polypropylene is preferably 0.3 g / 10 min or more, more preferably 0.4 g / 10 min or more, and even more preferably 0.5 g / 10 min or more. The MFR is measured according to JIS K7210:1999 under conditions of 230°C and a load of 2.16 kg.

[0074] From the above viewpoints, the melting point of the polypropylene is more preferably 148° C. or higher, further preferably 150° C. or higher, and particularly preferably 155° C. or higher. On the other hand, the upper limit of the melting point of the polypropylene is not particularly limited, but is preferably 175° C. or lower. The melting point of the polypropylene can be measured by a method in accordance with JIS K7121-2012.

[0075] From the viewpoint of heat resistance and extraction resistance, the antioxidant has a melting point of preferably 60° C. or higher, more preferably 70° C. or higher, even more preferably 75° C. or higher, particularly preferably 80° C. or higher or 90° C. or higher. Also, the melting point is preferably 300° C. or lower, more preferably 250° C. or lower.

[0076] The molecular weight of the antioxidant is not particularly limited, but is preferably 550 to 1,300, more preferably 580 to 1,280, further preferably 600 to 1,250, and particularly preferably 700 to 1,200, for example.

[0077] Examples of the antiaging agent include phenol-based antiaging agents, amine-based antiaging agents, imidazole-based antiaging agents, and phosphoric acid-based antiaging agents. The antiaging agent may be composed of only one of these, or may be composed of two or more of these. Among these, phenol-based antiaging agents are preferred from the viewpoint of being more excellent in heat resistance. Furthermore, among the phenol-based antiaging agents, hindered phenol-based antiaging agents are particularly preferred from the viewpoint of heat resistance.

[0078] Examples of hindered phenol-based antioxidants include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (e.g., BASF's "Irganox 1010", melting point 110-125°C, molecular weight 1178), 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate (e.g., BASF's "Irganox 3114", melting point 220-222°C, molecular weight 784), 2,4,6-tris(4-hydroxy-3,5-di-tert-butylbenzyl)mesitylene (e.g., BASF's "Irganox 1330", melting point 248-252°C, molecular weight 775), 6-(4-hydroxy-3,5-di-tert-butylanilino)-2,4-bis(octyl thio)-1,3,5-triazine (e.g., BASF's "Irganox 565", melting point 91 to 96 ° C.), 2,2'-thiodiethyl bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (e.g., BASF's "Irganox 1035", melting point 63 to 78 ° C.), N,N'-hexamethylene bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propanamide] (e.g., BASF's "Irganox 1098", melting point 156 to 161 ° C., molecular weight 637), 1,6-hexanediol bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (e.g., BASF's "Irganox 259", melting point 104 to 108 ° C., molecular weight 639), and the like.

[0079] From the viewpoint of heat resistance and extraction resistance, the content of the antioxidant is preferably relatively small relative to the polypropylene, specifically, 0.1 part by mass or more and 1.0 part by mass or less relative to 100 parts by mass of polypropylene.

[0080] The laminate tube according to the present invention may be a laminate tube having a three-layer structure as shown in Fig. 1, or may be a laminate tube having a two-layer structure of an inner layer and an outer layer, omitting the adhesive layer 16. Furthermore, other resin layers, rubber layers, or reinforcing layers (layers formed by braiding reinforcing threads such as PET threads) may be laminated on the outer peripheral surface of the outer layer.

[0081] Fig. 3 shows a laminate tube according to another embodiment of the present invention, and Fig. 4 shows a cross-sectional view of the laminate tube shown in Fig. 3 in a range of 100 µm in the axial direction.

[0082] As shown in Fig. 3, a laminate tube 20 according to another embodiment of the present invention has an inner layer 22 and an outer layer 24. Each of the inner layer 22 and the outer layer 24 is configured in a tubular shape. The laminate tube 20 has a two-layer laminate structure in which, from the inside, the inner layer 22 and the outer layer 24 are laminated in a tubular shape. The outer layer 24 is disposed on the outer peripheral surface of the inner layer 22 in contact with the inner layer 22.

[0083] The laminate tube 20 has an inner layer 22 containing polypropylene and an outer layer 24 containing polyamide. The outer layer 24 containing polyamide ensures strength and heat resistance. The inner layer 22 containing polypropylene prevents the fluid flowing through the laminate tube 20 from coming into contact with the outer layer 24 containing polyamide, thereby preventing a decrease in strength due to hydrolysis. Since the inner layer 22 containing polypropylene is protected by the outer layer 24 containing polyamide against the internal pressure of the fluid flowing through the laminate tube 20, the interlayer adhesion between the inner layer 22 containing polypropylene and the outer layer 24 containing polyamide is important. Since polypropylene and polyamide generally have low adhesion, in the laminate tube 20, acid-modified polypropylene is used for the inner layer 22 in contact with the outer layer 24 containing polyamide.

[0084] 4, 24a is the outer peripheral surface of the outer layer 24. 22a is the outer peripheral surface of the inner layer 22. 22b is the inner peripheral surface of the inner layer 22. The axial direction of the laminate tube 20 is the direction in which the laminate tube 20 extends, which is the X direction in FIGS.

[0085] As shown in FIG. 4, in the laminated tube 20, the ratio (b' / a') of the length a' of the outer peripheral surface 24a of the outer layer 24 to the length b' of the outer peripheral surface 22a of the inner layer 22 within a range of 100 μm in the axial direction is 1.003 or more and 1.050 or less. The outer peripheral surface 24a of the outer layer 24 is a portion that contacts the molding die during extrusion molding, and is a portion where the generation of undulations during extrusion molding is suppressed. Therefore, it can be expressed as a length that is free of undulations and is close to a straight line. The ratio (b' / a') of the length b' of the outer peripheral surface 22a of the inner layer 22 to the length a' of the outer peripheral surface 24a exceeds 1.000. By making the length b' of the outer peripheral surface of the inner layer 22 longer than the length a' of the outer peripheral surface of the outer layer 24, the contact area between the inner peripheral surface of the outer layer 24 and the outer peripheral surface of the inner layer 22 becomes large, and the interlayer adhesion between the inner layer 22 and the outer layer 24 becomes excellent.

[0086] In the present invention, the waviness of the outer peripheral surface of the inner layer 22 is intentionally increased, and the contact area between the outer peripheral surface of the inner layer 22 and the inner peripheral surface of the outer layer 24 is increased, thereby improving the interlayer adhesion between the inner layer 22 and the outer layer 24. If the ratio (b' / a') is less than 1.003, the improvement in adhesion due to the increased contact area is insufficient. If the ratio (b' / a') is more than 1.050, the waviness of the outer peripheral surface of the inner layer 22 becomes too large, resulting in a decrease in adhesion. Methods for increasing the waviness of the outer peripheral surface of the inner layer 22 include changing the extrusion temperature of each layer during extrusion molding to increase the viscosity difference between the layers, thereby forming waviness larger than the unavoidable waviness that occurs naturally, and blending organic polymer particles 18 into the material of the inner layer 22 to generate convex or concave portions due to the organic polymer particles 18 on the outer peripheral surface of the inner layer 22.

[0087] From the viewpoint of improving adhesion due to an increase in the contact area, the ratio (b' / a') is preferably 1.005 or more, more preferably 1.007 or more. Also, from the viewpoint of suppressing a decrease in adhesion due to an increase in waviness, the ratio (b' / a') is preferably 1.040 or less, more preferably 1.030 or less.

[0088] The length a' of the outer peripheral surface 24a of the outer layer 24 and the length b' of the outer peripheral surface 22a of the inner layer 22 can be obtained from an image of a cross section observed by cutting the laminate tube 20 in half in the axial direction and photographing it with a scanning electron microscope (SEM). The above lengths a' and b' can be measured in the same manner as the lengths a and b of the laminate tube 10.

[0089] The inner layer 22 includes acid-modified polypropylene. The inner layer 22 includes acid-modified polypropylene as a matrix polymer. This provides excellent adhesion to the outer layer 14 including polyamide. The inner layer 22 may include acid-modified polypropylene as a matrix polymer and may be composed of a resin composition including organic polymer particles 18 in the matrix of the acid-modified polypropylene. The matrix polymer is the main component of the inner layer 22. The main component is 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The polymer component of the inner layer 22 may be composed of only acid-modified polypropylene, or may include a polymer component such as polypropylene that is not modified with acid. In this case, the acid-modified polypropylene of the polymer components of the inner layer 22 may be preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The inner layer 22 does not necessarily have to include organic polymer particles 18.

[0090] The configuration of the inner layer 22 in the laminate tube 20 is the same as that of the adhesive layer 16 in the laminate tube 10. The configuration of the acid-modified polypropylene, the configuration of the organic polymer particles 28, the configuration of other added components, and the like are the same as those of the adhesive layer 16 in the laminate tube 10. Similarly to the inner layer 12 of the laminate tube 10, a predetermined antioxidant may be added to the inner layer 22 of the laminate tube 20. Similarly to the inner layer 12 of the laminate tube 10, the polypropylene of the inner layer 22 of the laminate tube 20 may have a predetermined MFR.

[0091] The configuration of the outer layer 24 in the laminate tube 20 is similar to the configuration of the outer layer 14 in the laminate tube 10 .

[0092] As shown in Fig. 4, in the laminate tube 20, the outer peripheral surface 22a of the inner layer 22 may have one or more convex portions or concave portions. The adhesiveness between the inner layer 22 and the outer layer 24 is improved by the anchor effect. The height of the convex portion or the depth of the concave portion is preferably 0.1 µm or more and 10 µm or less, and more preferably 0.1 µm or more and 5 µm or less. The adhesiveness between the inner layer 22 and the outer layer 24 is improved by the anchor effect. The convex portion and the concave portion are relative terms, and either may be used in the expression.

[0093] From the viewpoint of the anchoring effect, the number of the convex or concave portions is preferably 2 or more per 100 μm in the length direction at any position. Also, it is preferable that the number of the convex or concave portions is 2 or more per 100 μm in the circumferential direction at any position. On the other hand, from the viewpoint of ensuring the adhesiveness of the acid-modified polypropylene, it is preferable that the number of the convex or concave portions is 100 or less per 100 μm in the length direction at any position. Also, it is preferable that the number of the convex or concave portions is 100 or less per 100 μm in the circumferential direction at any position. The number of the convex or concave portions can be calculated by photographing a cross section of the inner layer 22 in a predetermined direction at a magnification of 5000 times with a scanning electron microscope (SEM) and connecting 10 of the images.

[0094] The above-mentioned convex or concave portions can be formed due to the blending of the organic polymer particles 28, or by changing the extrusion temperature of each layer to increase the difference in viscosity between the layers.

[0095] The tear strength in the longitudinal direction of the inner layer 22 is preferably 20 N / mm or more, more preferably 25 N / mm or more, and even more preferably 30 N / mm or more. For example, the inner layer 22 can satisfy the above tear strength by being composed of a resin composition containing organic polymer particles 18 in a matrix of acid-modified polypropylene. The above tear strength can be measured in the same manner as the tear strength of the adhesive layer 16 of the laminate tube 10.

[0096] The adhesive strength at the interface between the inner layer 22 and the outer layer 24 is preferably 30 N / cm or more, more preferably 35 N / cm or more, and even more preferably 40 N / cm or more. For example, the adhesive strength at the interface can be satisfied by adjusting the amount of acid modification of the acid-modified polypropylene, the amine value of the polyamide, the ratio (b' / a') of the length a' of the outer peripheral surface of the outer layer 24 to the length b' of the outer peripheral surface of the inner layer 22, the amount of the organic polymer particles 28 blended, and the like. The adhesive strength at the interface can be measured in the same manner as the adhesive strength at the interface between the adhesive layer 16 and the outer layer 14 of the laminate tube 10.

[0097] The laminate tube 20 can be manufactured as follows. First, a composition constituting the inner layer 22 and a composition constituting the outer layer 24 are prepared. Each composition is pelletized as necessary. Next, using an extruder, each composition is melt-extruded (co-extruded) into a tubular shape on a mandrel. This makes it possible to obtain the laminate tube 20 having a two-layer laminate structure in which the inner layer 22 and the outer layer 24 are laminated in a tubular shape from the inside.

[0098] Each layer is preferably extruded at a temperature of 200 to 350°C (preferably 220 to 280°C) and a take-up speed of 1 to 15 m / min (preferably 3 to 5 m / min). When melt extrusion (co-extrusion) is performed at a temperature 20 to 100°C higher (preferably 20 to 80°C higher) than the melting point of the polyamide of the outer layer 24, the organic polymer particles 28 in the inner layer 22 tend to be unevenly distributed near the interface between the inner layer 22 and the outer layer 24. This increases the waviness of the outer peripheral surface of the inner layer 22 due to the organic polymer particles 28, and increases the contact area between the inner peripheral surface of the outer layer 24 and the outer peripheral surface of the inner layer 22, resulting in excellent interlayer adhesion between the inner layer 22 and the outer layer 24.

[0099] The laminate tube 20 having the above-mentioned configuration has an inner layer 22 containing polypropylene and an outer layer 24 containing polyamide, in which the polypropylene contains acid-modified polypropylene, and the ratio (b' / a') of the length a' of the outer peripheral surface of the outer layer 24 to the length b' of the outer peripheral surface of the inner layer 22 within a range of 100 μm in the axial direction is 1.003 or more and 1.050 or less. The length b' of the outer peripheral surface of the inner layer 22, which is the adhesive interface between the inner layer 22 containing polypropylene and the outer layer 24 containing polyamide, is longer than the length a' of the outer peripheral surface of the outer layer 24, so that the contact area between the inner peripheral surface of the outer layer 24 and the outer peripheral surface of the inner layer 22 is large, and therefore the interlayer adhesion between the inner layer 22 containing polypropylene and the outer layer 24 containing polyamide is excellent. In addition, since the inner layer 22 contains acid-modified polypropylene, the adhesion to the outer layer 24 containing polyamide is further improved. As a result, the interlayer adhesion between the inner layer 22 containing polypropylene and the outer layer 24 containing polyamide is excellent.

[0100] The laminate tube 20 can be used for the same purposes as the laminate tube 10. The inner diameter of the laminate tube 20, the thickness of the inner layer 22, and the thickness of the outer layer 24 can also be configured similarly to the laminate tube 10.

[0101] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. EXAMPLES

[0102] The present invention will be described in detail below using examples and comparative examples.

[0103] (Examples 1-7, Comparative Examples 1-2) (outer layer material) The commercially available polyamides shown below were used as the outer layer materials.

[0104] (Preparation of Adhesive Layer Material) The components were blended in the ratio (parts by mass) shown in the table, and mixed at 200°C for 5 minutes using a twin-screw kneading extruder (Toshiba Machine's "TEM-18SS") to obtain a mixture, which was then pelletized to prepare the adhesive layer material.

[0105] (Preparation of inner layer material) The commercially available polypropylenes shown below were used as the inner layer materials.

[0106] (Preparation of laminated tube) The outer layer material, adhesive layer material, and inner layer material were melt-extruded (co-extrusion) into a tube using a multi-layer extrusion molding machine (manufactured by Plastics Engineering Research Institute) capable of co-extrusion molding to produce a three-layer laminated tube (inner layer thickness 0.6 mm, adhesive layer thickness 0.1 mm, outer layer thickness 0.3 mm, inner diameter 12 mm). The extrusion temperature of each material was set to a temperature 20°C higher than the melting point, and the take-up speed was 3 m / min.

[0107] (Example 8, Comparative Example 3) (outer layer material) The commercially available polyamides shown below were used as the outer layer materials.

[0108] (Preparation of inner layer material) The components were blended in the ratio (parts by mass) shown in the table and mixed at 200°C for 5 minutes using a twin-screw kneading extruder (Toshiba Machine's "TEM-18SS") to obtain a mixture, which was then pelletized to prepare the inner layer material.

[0109] (Preparation of laminated tube) The outer layer material and the inner layer material in the combination shown in the table were melt-extruded (co-extrusion) into a tube using a multi-layer extrusion molding machine capable of co-extrusion molding (manufactured by the Plastics Engineering Research Institute) to produce a two-layer laminated tube (inner layer thickness 0.7 mm, outer layer thickness 0.3 mm, inner diameter 12 mm). The extrusion temperature of each material was set to a temperature 20°C higher than the melting point, and the take-up speed was 3 m / min.

[0110] The materials used are as follows: (Material for outer layer) ·PA <1> : Polyamide, Daicel Evonik "SX8002", melting point 211℃, amine value 70.7mmol / g ·PA <2> : Polyamide, DuPont "Zytel RSLC3060", melting point 223°C, amine value 52.0mmol / g ·PA <3> : Polyamide, Toray "CM2001", melting point 222℃, amine value 18.0mmol / g

[0111] (Material for adhesive layer) Acid-modified PP <1> : Maleic anhydride modified polypropylene, Mitsui Chemicals "Admer QF500", modification amount 0.27 mass%, melting point 165℃ ·EP copolymer <1> : Ethylene-propylene copolymer, "Tafmer DF840" manufactured by Mitsui Chemicals ·EP copolymer <2> : Ethylene-propylene copolymer, "Tafmer DF8200" manufactured by Mitsui Chemicals

[0112] (Inner layer material) Block PP: Propylene-α-olefin block copolymer, Prime Polymer "E-702MG", MFR 1.4g / 10min, melting point 162℃ Acid-modified PP <1> Maleic anhydride modified polypropylene (Mitsui Chemicals "Admer QF500"), modification amount 0.27 mass%, melting point 165°C ·EP copolymer <1> : Ethylene-propylene copolymer (Mitsui Chemicals "Tafmer DF840") ·EP copolymer <2> : Ethylene-propylene copolymer (Mitsui Chemicals "Tafmer DF8200")

[0113] The obtained laminated tube was split in half in the axial direction, and the cross section was photographed at a magnification of 5000 times with a scanning electron microscope (SEM), and 10 images were joined together. Based on the images, the length a of the outer surface of the outer layer and the length b of the outer surface of the adhesive layer were measured within a range of 100 μm in the axial direction for the three-layer laminated tube, and the ratio (b / a) was calculated. For the two-layer laminated tube, the length a' of the outer surface of the outer layer and the length b' of the outer surface of the inner layer were measured within a range of 100 μm in the axial direction, and the ratio (b' / a') was calculated. Based on the images, the particle sizes of 10 organic polymer particles confirmed in the adhesive layer or the inner layer were measured, and the average particle size (μm) was calculated. In addition, for those images in which a convex portion was observed on the adhesive layer or the inner layer side at the interface between the adhesive layer or the inner layer and the outer layer, the number of convex portions (pieces / 100 μm) in the linear distance at the interface was counted. The results are shown in the table below.

[0114] Each of the obtained laminated tubes was evaluated for each property according to the following criteria, and the results are shown in the table below.

[0115] <Interface adhesion> The laminated tube thus produced was cut in half, and a strip-shaped test piece with a width of 10 mm was produced from the cut tube. The end of the test piece was then peeled off with nippers, the peeled off portion was gripped, and the test piece was pulled at a speed of 25 mm / min with a tensile tester to perform delamination. At this time, the average adhesive strength (N / cm) when the peel strength remained stable for 30 seconds was measured and expressed as "adhesive strength (N / cm)". Adhesive strength of 40 N / cm or more was marked with "◎", adhesive strength of 20 N / cm or more but less than 40 N / cm was marked with "○", and adhesive strength of less than 20 N / cm was marked with "×".

[0116] [Table 1]

[0117] [Table 2]

[0118] In Comparative Example 1, in a laminated tube having a three-layer structure of an inner layer, an outer layer, and an adhesive layer, the ratio (b / a) of the length a of the outer peripheral surface of the outer layer to the length b of the outer peripheral surface of the adhesive layer in an axial range of 100 μm is 1.000, which is less than 1.003. In Comparative Example 1, the effect of increasing the contact area is not obtained, and the interlayer adhesion between the adhesive layer and the outer layer is insufficient. In Comparative Example 2, the length ratio (b / a) is 1.058, which is more than 1.050. In Comparative Example 2, the waviness of the outer peripheral surface of the adhesive layer becomes too large, and the interlayer adhesion between the adhesive layer and the outer layer is insufficient. On the other hand, in Examples 1-7, the length ratio (b / a) is 1.003 or more and 1.050 or less. The length b of the outer peripheral surface of the adhesive layer that bonds the inner layer containing polypropylene and the outer layer containing polyamide is longer than the length a of the outer peripheral surface of the outer layer, so that the contact area between the inner peripheral surface of the outer layer and the outer peripheral surface of the adhesive layer is large, resulting in excellent interlayer adhesion between the adhesive layer and the outer layer. In addition, since both the adhesive layer and the inner layer contain polypropylene, the adhesive layer and the inner layer have excellent interlayer adhesion, which results in excellent interlayer adhesion between the inner layer containing polypropylene and the outer layer containing polyamide.

[0119] In Comparative Example 3, in a laminated tube having a two-layer structure of an inner layer and an outer layer, the ratio (b' / a') of the length a' of the outer peripheral surface of the outer layer to the length b' of the outer peripheral surface of the adhesive layer within an axial range of 100 μm is 1.000, which is less than 1.003. In Comparative Example 3, the effect of increasing the contact area is not obtained, and the interlayer adhesion between the inner layer and the outer layer is insufficient. On the other hand, in Example 8, the above-mentioned length ratio (b' / a') is 1.003 or more and 1.050 or less. Since the length b' of the outer peripheral surface of the inner layer, which is the adhesive interface between the inner layer containing polypropylene and the outer layer containing polyamide, is longer than the length a' of the outer peripheral surface of the outer layer, the contact area between the inner peripheral surface of the outer layer and the outer peripheral surface of the inner layer is increased, and therefore the interlayer adhesion between the inner layer containing polypropylene and the outer layer containing polyamide is excellent.

[0120] Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments and examples, and various modifications are possible without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0121] 10. Laminated tube 12 Inner layer 14 Outer layer 16 Adhesive layer 18 Organic polymer particles 14a (Outer layer) outer surface 16a (Adhesive layer) outer surface 16b (Adhesive layer) inner surface 20 Laminated tube 22 Inner layer 24 Outer layer 28 Organic polymer particles 22a (inner layer) outer surface 24a (Outer layer) outer surface X Axial direction of stacked tube

Claims

1. A laminated tube having an inner layer containing polypropylene and an outer layer containing polyamide, an adhesive layer containing acid-modified polypropylene between the inner layer and the outer layer; A laminate tube, wherein the ratio (b / a) of the length a of the outer peripheral surface of the outer layer to the length b of the outer peripheral surface of the adhesive layer within an axial range of 100 μm is 1.003 or more and 1.050 or less.

2. A laminated tube having an inner layer containing polypropylene and an outer layer containing polyamide, The polypropylene includes an acid-modified polypropylene, A laminate tube, wherein the ratio (b' / a') of the length a' of the outer peripheral surface of the outer layer to the length b' of the outer peripheral surface of the inner layer within an axial range of 100 μm is 1.003 or more and 1.050 or less.

3. 2. The laminate tube according to claim 1, wherein the adhesive layer is made of a resin composition containing organic polymer particles in a matrix of acid-modified polypropylene.

4. 3. The laminate tube according to claim 2, wherein the inner layer is made of a resin composition containing organic polymer particles in a matrix of acid-modified polypropylene.

5. 5. The laminate tube according to claim 3, wherein the organic polymer particles are composed of an ethylene-propylene copolymer or an ethylene polymer.

6. 5. The laminate tube according to claim 3, wherein the content of the organic polymer particles is 5 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the acid-modified polypropylene matrix.

7. 5. The laminate tube according to claim 3, wherein the organic polymer particles have an average particle size of 0.1 μm or more and 10 μm or less.

8. 3. The laminate tube according to claim 1, wherein the amine value of the polyamide is from 15 mmol / kg to 100 mmol / kg.

9. 9. The laminate tube according to claim 8 dependent on claim 1, wherein the adhesive strength at the interface between the adhesive layer and the outer layer is 30 N / cm or more.

10. 9. The laminate tube according to claim 8 dependent on claim 2, wherein the adhesive strength at the interface between the inner layer and the outer layer is 30 N / cm or more.

11. 3. The laminate tube according to claim 1, which is used as a tube for transporting a coolant for a vehicle.

12. the adhesive layer is composed of a resin composition containing organic polymer particles in a matrix of acid-modified polypropylene; the organic polymer particles are composed of an ethylene-propylene copolymer or an ethylene polymer, the content of the organic polymer particles is 5 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of the acid-modified polypropylene matrix, The organic polymer particles have an average particle size of 0.1 μm or more and 10 μm or less, The amine value of the polyamide is 15 mmol / kg or more and 100 mmol / kg or less, 2. The laminate tube according to claim 1, wherein an adhesive strength at an interface between said adhesive layer and said outer layer is 30 N / cm or more.

13. the inner layer is made of a resin composition containing organic polymer particles in a matrix of acid-modified polypropylene; the organic polymer particles are composed of an ethylene-propylene copolymer or an ethylene polymer, the content of the organic polymer particles is 5 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of the acid-modified polypropylene matrix, The organic polymer particles have an average particle size of 0.1 μm or more and 10 μm or less, The amine value of the polyamide is 15 mmol / kg or more and 100 mmol / kg or less, 3. The laminate tube according to claim 2, wherein an adhesive strength at the interface between the inner layer and the outer layer is 30 N / cm or more.

Images