JP2000271996A - Method for bending thermoplastic resin hose - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily bend a large diameter thermoplastic resin hose without kinking by forming a bend at a bellows portion of the hose having a specific inner diameter or above. SOLUTION: A multilayer hose has an outermost layer and an innermost layer of two layers. Further, the hose is the multilayer hose in which one intermediate layer is arranged as a three-layer hose or two or above intermediate layers are arranged. In this case, its inner diameter is 10 mm or above. A melting point of the resin for forming the outermost layer is lower than that of the resin for constituting the innermost layer or the intermediate layer. The hose is bent at a temperature of the melting point of the resin for forming the outermost layer, and inside bellows of the bends are partly fusion bonded to each other. Thus, since the hose has excellent bend transferability and mold settability and is not kinked or not flattened in section when bent, the bent hose having no kink, no sectional flat and excellent pressure resistant deformability can be efficiently manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for bending a large diameter resin hose.

[0002]

2. Description of the Related Art Thermoplastic resin hoses are used mainly for ducts and fuel lines in an engine room of an automobile, and these hoses are blow-molded using polyamide resin or saturated polyester resin. It is generally manufactured by extrusion. Among such hoses, when the inner diameter is small, such as a fuel line hose made of nylon 11 having an inner diameter of 6 mm, the hose is relatively flexible and has excellent kink properties. By setting and heating and cooling, a bent hose having a predetermined bent shape can be easily manufactured.

[0003] However, when the diameter of the hose is large, the hose is easily kinked, and it is difficult to set the hose with a small bending radius in a mold, and the hose having a small bending radius cannot be bent. Therefore, there is a method of bending the hose by filling it with sand or the like in order to prevent kink, but it takes time to put and take out the filling and the productivity is poor. In addition, there is also a problem that a large force is required for setting in a mold, so that it is not possible to substantially perform continuous production. Therefore, large-diameter bent hoses are generally manufactured as a molded product having a bent shape by blow molding or three-dimensional blow molding. However, there is a disadvantage that equipment cost is high because one mold is required for one shape. Furthermore, in the blow molding, burrs are easily generated, but in the case of a multilayer molded product, there is a problem that the resin in the generated burrs cannot be recycled.

[0004] In addition, as characteristics required for a bent hose for an automobile, high heat resistance, barrier properties such as gasoline, LLC, chlorofluorocarbon, etc., chemical resistance and pressure deformation resistance are required. The used polyamide hose and polyester hose have insufficient barrier properties and heat resistance for various chemicals. Therefore, as a method of improving the chemical barrier property of a tube of a polyamide resin or a polyester resin, a method of blending or laminating a thermoplastic resin having a low chemical permeability to a polyamide resin or a polyester resin has been proposed. I have.

For example, as a method of blending a polyamide resin with a resin having low chemical permeation, Japanese Patent Laid-Open Publication No.
No. 38, a resin composition in which a soft fluororesin is blended with a nylon resin. This blend composition is a molding material having both the chemical barrier properties of a fluororesin and the mechanical properties and low-temperature impact properties of a polyamide resin, but has the drawback that a hose made of this resin is easily torn in the extrusion direction. As a method of forming a resin having low chemical permeation into a multilayer structure, for example, Japanese Patent Application Laid-Open No.
No. 843 discloses a soft fluororesin composition in which the inner layer is a fluororesin, the adhesive layer is a soft fluororesin and a polyamide resin or a polyurethane resin, and a multilayer molded article in which the outer layer is a polyamide resin. This is because it has high chemical barrier properties and chemical resistance, but it requires a special extruder for fluororesin, not enough low-temperature impact resistance, and because fluororesin is very flexible, Large diameter hoses have the disadvantage that they are prone to kink.

[0006] Polyphenylene sulfide resin (hereinafter referred to as
PPS resin is an engineering plastic with excellent heat resistance, hot water resistance, chemical resistance, gas barrier properties, abrasion resistance, flame retardancy, etc., and is therefore suitable for applications such as electric, electronic, and automotive parts. . Therefore, molding that combines the properties of PPS resin such as heat resistance, chemical resistance, hot water resistance and chemical barrier properties with the moldability and economical properties of thermoplastic resins such as polyamide resins and saturated polyester resins. It has been proposed to laminate both of these materials to obtain a product. However, a large-diameter resin hose made of a polyamide-based resin or a saturated polyester-based resin is difficult to bend even with a single-layer hose, so that if a relatively hard and low-tough PPS resin is laminated, the bending becomes more difficult. There's a problem.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention has been achieved as a result of studying to solve the problems of the prior art described above.
It is intended to provide a method for easily bending a large diameter resin hose without kinking, and is particularly suitable for a multilayer bend hose excellent in heat resistance, hot water resistance, chemical resistance and gas barrier properties. A bending method is provided.

[0008]

Means for Solving the Problems The present inventors have proposed an inner diameter of 10 mm.
After examining the kink properties of bent hoses obtained by heating and cooling after setting various types of thermoplastic resin hoses with a large diameter of at least mm, the bellows shape is extremely effective in preventing kink during bending. And arrived at the present invention. That is, the method for bending a thermoplastic resin hose of the present invention includes forming a bend in a bellows-shaped portion of a thermoplastic resin hose having an inner diameter of 10 mm or more, and forming a bend in a state in which the bent portion is heated in advance. Bending is performed by a method of setting in a mold and cooling, or a method of heating and cooling in a state where a bent portion is set in a bending die.

In the case of a hose having an inner diameter of 10 mm or more, the flatness of a bent portion due to bending becomes large. Therefore, if the bending radius is small, kink is generated, and a large amount of labor is required when setting a mold. However, by making the bent portion bellows-shaped, it is possible to prevent kink and greatly reduce the labor required for setting the mold. The inner diameter is 1
A small-diameter hose having a diameter of less than 0 mm has a relatively good kink property and can be easily set in a mold, so that a bellows shape is not particularly necessary. However, a bent portion may be formed in a bellows shape.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thermoplastic resin hose to which the method of the present invention is applied may be a single-layer hose made of a thermoplastic resin or a multi-layer hose formed by laminating a plurality of polymers. It is effective in the case. Hereinafter, a multi-layer hose will be described as an example. As this multi-layer hose,
It may be any of a hose composed of two layers, an outermost layer and an innermost layer, a three-layer hose in which one intermediate layer is arranged, and a multi-layer hose in which two or more intermediate layers are arranged.

A preferred resin composition of the multilayer hose is that the melting point of the resin forming the outermost layer is lower than the melting points of the resins forming the innermost layer and the intermediate layer. The bending process is performed at a temperature equal to or higher than the melting point of the resin forming the outermost layer, and the bellows on the inside of the bend are partially fused to each other. Deformability is significantly improved.

In the multi-layer hose, the thermoplastic resin forming the outer layer is not particularly limited as long as it can be extruded. For example, a polyamide resin or a saturated polyester resin is preferable from the viewpoint of moldability, mechanical properties and economy. preferable. For at least one of the inner layer and the intermediate layer, it is preferable to use a thermoplastic resin which is extrudable and has good chemical resistance, for example, chemical resistance, mechanical properties, thermal properties, and economy. And PPS resins are preferred.

As the polyamide resin for the outer layer used in the multilayer hose, polycaproamide (nylon 6),
Polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polyhexamerylensebacamide (nylon 610), polyhexamylylene dodecamide (nylon 612), polydodecaneamide (nylon 12), polyundecaneamide (nylon 11), polyhexamethylene terephthalamide (nylon 6T), polyxylylene adipamide (nylon X
D6) and mixtures or copolymers thereof.

Among these, nylon 6, nylon 66,
Nylon 11, nylon 12, and copolymers thereof are preferred in terms of heat resistance, moldability, and economy. The degree of polymerization of the polyamide resin is not particularly limited, and the relative viscosity measured at 25 ° C. in a 98% concentrated sulfuric acid solution is in the range of 1.5 to 7.0, particularly in the range of 1.8 to 6.5. Are preferred.

The saturated polyester resin has at least 6
An aromatic polyester obtained from a dicarboxylic acid in which 0 mol% is terephthalic acid and an aliphatic diol. As dicarboxylic acids other than terephthalic acid, azelaic acid,
Sebacic acid, adipic acid, aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as dodecanedicarboxylic acid, isophthalic acid,
An aromatic dicarboxylic acid such as naphthalenedicarboxylic acid, or an alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid, alone or in a mixture. Examples of the aliphatic diol include ethylene glycol, propylene glycol, 1,4-butanediol, trimethylene glycol, hexamethylene glycol and the like.

Preferred examples of the saturated polyester resin include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, and polycyclohexylene dimethylene terephthalate. Among them, from the viewpoint of having an appropriate mechanical strength, Polybutylene terephthalate or a copolymerized polyester comprising terephthalic acid in an amount of 60 mol% or more, preferably 70 mol% or more, and a dicarboxylic acid component containing dodecanedicarboxylic acid and / or isophthalic acid and a 1,4-butanediol component is particularly preferable.

The polybutylene terephthalate (hereinafter P)
BT resin) and the degree of polymerization of the copolymerized polyester are not particularly limited, and the relative viscosity of the 0.5% orthochlorophenol solution measured at 25 ° C. is in the range of 0.5 to 2.5, particularly 0.8 to 0.8. Those having a range of from 2.0 to 2.0 are preferable. The degree of polymerization of polyethylene terephthalate is not particularly limited, and the intrinsic viscosity of a 0.5% orthochlorophenol solution measured at 25 ° C. is in the range of 0.54 to 1.5.
Particularly, those having a range of 0.6 to 1.2 are preferable.

As the PPS resin used in the present invention, any PPS resin that can be produced by a known method can be used. In order to improve various properties of the PPS resin, a polyamide resin, a polyester resin, and a polyolefin resin may be blended. A polyolefin-based elastomer having no functional group, such as an ethylene-propylene copolymer, an ethylene-butene copolymer, and a polybutene Diene such as polyolefin elastomer such as ethylene-propylene diene copolymer and ethylene-vinyl acetate copolymer, styrene butadiene copolymer, polybutadiene, butadiene-acrylonitrile copolymer, polyisoprene and butene-isoprene copolymer -Based elastomers and their hydrogenated products, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-isopropyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene- And acrylic elastomers, such as methacrylic acid ethyl acrylate copolymer, a polyolefin elastomer having a functional group, such as polyethylene, polypropylene, polystyrene, ethylene - propylene copolymer,
Ethylene-butene copolymer, polybutene, ethylene-propylene-diene copolymer, styrene-butadiene copolymer, polybutadiene, butadiene-acrylonitrile copolymer, polyisoprene, butene-isoprene copolymer, and styrene-ethylene-butadiene -Maleic anhydride, succinic anhydride, fumaric anhydride, acrylic acid, methacrylic acid, vinyl acetate and its Na, Zn, K, Ca,
Blend with salts such as Mg, olefin copolymers copolymerized with methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, etc. Or two or more elastomers may be used in combination.

A multilayer hose or a single-layer hose made of such a thermoplastic resin requires that at least a portion forming a bend has a bellows shape. For example, a bellows shape may be formed on the entire hose. Alternatively, the bellows shape may be formed only in a part including a part forming a bend.

The hose having the bellows shape is supplied to the extruder by, for example, a conventional extruder or blow molding method to melt and knead the thermoplastic resin composition. After it is made to flow, it can be extruded into a hose shape out of the die, shaped into a bellows shape with an ordinary corrugator, and cooled to produce a product.

In the bellows hose having a two-layer structure, the resin for the outer layer and the resin for the inner layer are melt-kneaded inside the extruder by the corrugating method described above, and supplied to a co-extrusion die.
It can be melt-bonded in a multilayer shape at the bonding portion in the co-extrusion die, co-extruded as a multilayer tubular body or a multilayer parison from the die face at the tip, shaped and cooled with a corrugator apparatus, and manufactured. In the case of a hose having three or more layers, a bellows-shaped multilayer hose can be manufactured by a method according to the above by forming a multilayer hose having three or more layers at the time of co-extrusion as described above.

At this time, the peak height and pitch of the bellows in the bellows shape may be determined optimally according to the hose diameter, bending angle, constituent resin, etc. In general, the peak height H is 5 to 30% of the hose diameter. The pitch is preferably 1 to 5 times the peak height.

The hose having the bellows manufactured in this manner is then bent. This bending is performed by setting the bent portion in a bent mold while heating the bent portion in advance, and cooling. Method, or
It may be performed by a method of heating and cooling in a state where the bent portion is set in the bending die.

The heating temperature at the time of the bending process should be equal to or higher than the Tg of the resin having the highest glass transition temperature (Tg) of the resin constituting each layer, in order to fix the bending shape after the bending process. Preferred for. That is, if a resin layer having a Tg higher than the bending temperature is present in the hose, it is not preferable because return after bending tends to occur. Further, it is preferable that the heating temperature at the time of the bending is set to be equal to or higher than the melting point of the resin forming the outermost layer, so that at least a partial fusion is formed at the bellows-shaped crest at the time of the bending. At this time, it is preferable to use a resin having a melting point higher than the resin melting point of the outermost layer as the other layer, and to perform bending at a temperature lower than the resin melting point of the other layer to maintain the hose shape at the time of bending.

FIG. 1 shows a bent portion of an example of a hose having a bent portion obtained in this manner. FIG. 1 is a longitudinal sectional view schematically showing a bent portion of a hose having a two-layer structure, which is formed of an outer layer material 1 and an inner layer material 2 and has a bellows shape having a peak height H and a pitch P.

Since the flexible bend hose obtained by the method of the present invention is excellent in heat workability and pressure deformation resistance, hoses for automobile parts such as radiator hoses, heater hoses, reservoir tank hoses, road heating pipes, floor heating, etc. It is effective as a cooling and heating hose such as a pipe and an air conditioning hose. In particular, in the case of a multi-layer hose in which the outermost layer is made of a polyamide-based resin or a saturated polyester-based resin and at least one layer other than the outermost layer is made of a polyphenylene sulfide-based resin, a thermoplastic resin having good chemical resistance and a moldability・ Because it is laminated with a thermoplastic resin having good mechanical properties, it is extremely effective as a resin hose for automobile parts that has strong demands for various chemical resistances and barrier properties.

[0027]

The present invention will be described in detail below with reference to examples. In addition, the kink property of the hose described in the following Examples and Comparative Examples, heat workability, pressure deformation after heat processing,
It was measured by the following method.

1. Kinking property The hose before bending was cut into a length of 500 mm, wound around a mandrel having a constant curvature, and a flattened shape having a flatness of 50% or less or a mandrel radius R when kink occurred was determined. 2. Flexibility The hose before bending was cut to a length of 500 mm, the hose was stretched horizontally to the ground, only one end was fixed, and a load of 100 g was applied to the other end to measure the amount of displacement in the load direction.

3. Bending transferability A bending hose obtained by bending was placed on a copying machine, the shape of the hose was copied, and the degree of bending was measured with a protractor. The ratio (%) of the obtained degree of bending to the degree of bending (90 degrees) of the mold was determined and defined as bending transferability. 4. Pressure Resistance Deformability One end of a bent hose obtained by setting the mold at a bending angle of 90 degrees was sealed with epoxy resin, and the opening of the L shape was measured when a water pressure of 4 kg / cm ^{2 was} applied from the other end. .

[Example 1] A PPS resin (Toray Industries, Inc. "Torelina" A670-X01) is supplied to a 30 mmφ extruder by a usual multilayer tube molding method, melt-kneaded at a cylinder temperature of 300 ° C, and co-extruded. It is supplied for the inner layer in the die, and further, nylon 11 resin (manufactured by Toray Industries, Inc .:
“Rilsan” BESNBKP20TL) was supplied to a 40 mmφ extruder, melt-kneaded at a cylinder temperature of 230 ° C., and supplied for an outer layer in a co-extrusion die. The two polymers are melt-bonded in layers at the joint in the co-extrusion die, and are co-extruded from the die face at the tip as a two-layer tubular body. This was shaped and cooled and solidified by an ordinary corrugator forming apparatus to form a two-layer corrugated hose having an outer diameter of 15 mm, an inner diameter of 12 mm, a wall thickness of 1.5 mm, a peak height of 2 mm, and a pitch of 5 mm. The thickness of each layer of the obtained hose was 1.0 mm for the outer layer and 0.5 mm for the inner layer. This hose was extremely excellent in kink property and flexibility and excellent in bending workability despite lamination of a PPS resin which is relatively easy to kink.

The obtained corrugated hose was cut into a length of 500 mm, and was set in an L-shaped mold bent at 90 degrees.
After heating at 0 ° C. for 15 minutes, the mixture was cooled to room temperature to produce a bent hose. The obtained bent hose had neither kink nor flat shape in the bent portion. Further, the TPS of the PPS resin having the highest Tg among the resins constituting each layer
Since it was bent at a temperature higher than g, it had good shape transfer performance for a set bending angle. On the other hand, when bending was performed at a heating temperature of 80 ° C. lower than the Tg of the PPS resin during bending, the bending transferability was insufficient at 70%.

Examples 2 and 3 A bellows hose was manufactured and bent in the same manner as in Example 1 except that the hose diameter of the bellows hose and the heating temperature during bending were changed as shown in Table 1. Even when the diameter of the hose was increased as in Example 2, good bending workability that could not be obtained with a straight hose was obtained. Further, when the heating temperature at the time of bending is set to 200 ° C. which is higher than the melting point of the nylon 11 resin forming the outer layer as in Example 3, the bellows of the bent portion are fused to each other to form a strong shape. It has a retentivity, and the pressure-resistant deformation under an internal pressure load is small and greatly improved.

[Examples 4 and 5] As shown in Table 1, the outer layer material of the hose was made of PBT resin ("Toraycon 5" manufactured by Toray Industries, Inc.).
201-X10) or nylon 6 resin (Toray Industries, Inc.)
Was manufactured and bent in the same manner as in Example 3 except that the bending temperature was changed to 240 ° C. Even if the diameter of the hose becomes large, the bending transfer property and the pressure deformation resistance do not change. Also, even if the outer layer material is changed to PBT resin or nylon 6 resin, the processing temperature is higher than that of the outer layer material. A bent hose was obtained.

Example 6 A plasticized nylon 11 resin ("Rilsan" BESNBKP20TL, manufactured by Toray Industries, Inc.) was mixed with 4
0 mmφ extruder, melt-kneaded at a cylinder temperature of 230 ° C., and formed into a cylindrical flow in an extrusion die. By a commercially available corrugating machine, the outer diameter is 36 mm, the inner diameter is 33 mm, the wall thickness is 1.5 mm, by a usual method. Mountain height 2mm, pitch 5
mm single-layer bellows hose was obtained. This bellows hose has excellent flexibility, kink properties and good thermal workability despite its large diameter.

[0035]

[Table 1]

[Comparative Example 1] A PPS resin (Toray Industries, Inc. “Torelina” A670-X01) was fed to a 30 mmφ extruder by a usual multilayer tube molding method, melt-kneaded at a cylinder temperature of 300 ° C, and co-extruded. The resin is supplied for the inner layer in the die, and further, plasticized nylon 11 resin (manufactured by Toray Industries, Inc .: "Rilsan" BESNBKP20TL) is added to the resin.
The mixture was supplied to a 0 mmφ extruder, melt-kneaded at a cylinder temperature of 230 ° C., and supplied for the outer layer in a co-extrusion die. The two-layer tubular body formed by laminating these two kinds of polymers in a die is subjected to an outer diameter of 3 by a conventional method using a commercially available tube forming apparatus.
A two-layer hose having a diameter of 6 mm, an inner diameter of 33 mm, and a thickness of 1.5 mm was formed. The thickness of each layer of the obtained straight hose was 1.0 mm for the outer layer and 0.5 mm for the inner layer. As shown in Table 2, the obtained straight hose was extremely inferior in kink performance and could not be simply bent and heat-processed.

Comparative Examples 2, 3 and Reference Example 1 Nylon 1
1 Resin ("Rilsan" BESNBKP20 manufactured by Toray Industries, Inc.)
TL) is fed to a 40 mmφ extruder, and the cylinder temperature 2
The mixture was melt-kneaded at 30 ° C., extruded as a cylindrical flow in an extrusion die, cooled and solidified by a sizing device to obtain a single-layer hose having an outer diameter and an inner diameter shown in Table 2 and having a thickness of 1.5 mm. Reference Example 1 has a thickness of 1 mm. In Comparative Examples 2 and 3, since the diameter of the hose was large, the kink property was greatly deteriorated, and the hose was not wound around a mandrel having a relatively small bending radius. Also, the flexibility was reduced, and a large force was required to wind the mandrel. In the case of Reference Example 1, the minimum bending radius was 2 because the diameter of the hose was small.
It was as small as 0 mm (R20) and had sufficient flexibility.

[0038]

[Table 2]

[0039]

According to the method of the present invention, it has excellent bending transfer properties and mold setting properties, and has no kink or cross-sectional flatness during bending, so that there is no kink or cross-sectional flatness and excellent It is possible to manufacture a long-lasting hose having pressure-resistant deformability with high efficiency. Further, when a bent hose is manufactured as a multilayer hose in which the outermost layer is made of a polyamide resin or a saturated polyester resin, and at least one layer other than the outermost layer is made of a polyphenylene sulfide resin,
It has surface appearance, heat resistance, antifreeze resistance, low-temperature impact resistance, gas barrier resistance, chemical resistance such as zinc chloride and calcium chloride, moldability, economic efficiency, etc., especially water or aqueous solution, fuel oil, A bent hose can be obtained which can be advantageously used in heat medium circulation pipe applications, such as automotive pipes used under high temperature conditions or for many years under direct contact with various mineral oils or for years, snow melting or heating systems for heating.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a bent portion of an example of a two-layer hose having a bent portion formed by the method of the present invention.

[Explanation of symbols]

1: Outer layer material, 2: Inner layer material, H: Bellows-shaped peak height, P: Bellows-shaped pitch

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H111 AA02 BA15 CA47 CB03 DA11 DA26 DB08 DB19 EA12 4F209 AA24 AA29 AA34 AG03 AG10 AG12 NA01 NB01 NG03 NG05 NH18 NK10

Claims (6)

[Claims] 1. A method of forming a bend in a bellows-shaped portion of a thermoplastic resin hose having an inner diameter of 10 mm or more, and a method of setting the bend-formed portion in a heated state in a bending mold and cooling it, or A method for bending a thermoplastic resin hose, wherein the bending is performed by a method of heating and cooling while the bent portion is set in a bending die. 2. The method for bending a thermoplastic resin hose according to claim 1, wherein the thermoplastic resin hose is a hose formed by laminating a plurality of polymer layers. 3. The heating temperature at the time of bending is higher than the glass transition temperature of the resin having the highest glass transition temperature among the thermoplastic resins forming the hose. Bending method of thermoplastic resin hose. 4. A bending process, wherein a resin having a lower melting point than the resin forming the inner layer is used as the resin forming the outermost layer, and the heating temperature at the time of bending is set to be equal to or higher than the melting point of the resin forming the outermost layer. 4. The method for bending a thermoplastic resin hose according to claim 2, wherein the bellows-shaped peak portion is sometimes fused at least partially. 5. The thermoplastic material according to claim 2, wherein the outermost layer is made of a polyamide resin or a saturated polyester resin, and at least one layer other than the outermost layer is made of a polyphenylene sulfide resin. Bending method for resin hoses. 6. A thermoplastic resin hose having a bent portion obtained by bending a thermoplastic resin hose by the method according to any one of claims 1 to 4.