JPH0794156B2 - Resin tube for fuel piping - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin tube for fuel piping, which is formed by using a fluororesin having particularly excellent lightness and rustproof property and further having high fuel barrier property (fuel impermeability). The present invention relates to a resin tube.

[0002]

BACKGROUND ART Conventionally, fuel piping tubes that have been used as the fuel piping itself or for connection thereof in automobiles and the like include various materials, such as metal tubes and resin tubes. Has been done.

In recent years, there is a problem that rust occurs, and in place of a metal tube which is very heavy and cannot cope with weight reduction of a vehicle, it is lightweight and does not rust.
Resin tubes have been widely used. In particular, the fluororesin tube has excellent fuel barrier properties (fuel impermeability) among various resin tubes, and it is not only used for ordinary gasoline but also for methanol blended gasoline expected to be used in the future. However, since it exhibits an excellent fuel barrier property, it can be said that it has the characteristics required for the fuel piping tube.

However, the cost of fluororesin is very high, and even if the tube is formed thin to reduce the cost, the fuel piping tube has a minimum thickness that can withstand the internal pressure of the fuel transported in the tube. Therefore, sufficient cost reduction cannot be achieved. Therefore, in order to reduce costs while ensuring excellent fuel barrier properties, an inner layer made of fluororesin is formed as thin as possible, while a low-cost resin such as polyamide resin is provided outside the inner layer. There has been provided a tube having a laminated structure, in which an outer layer made of is laminated to obtain a required tube thickness.

Since the fluororesin has poor adhesiveness to other resin materials, it is necessary to perform a predetermined adhesive treatment between both layers when forming such a laminated resin tube. Specifically, first, a fluororesin tube that is an inner layer is extrusion-molded, and a sodium-ammonia complex or a chemical treatment liquid containing a sodium-naphthalene complex is applied to the surface of the tube to perform a surface treatment for introducing an active group. After applying the phenolic adhesive, if necessary,
The outer layer had to be laminated with a resin material such as polyamide resin. Therefore, there is a problem that the manufacturing process of the laminated resin tube is significantly complicated.

[0006]

The present invention has been made under such circumstances, and a problem to be solved by the present invention is to provide a laminate having a fluororesin layer and a layer made of another resin material outside thereof. When manufacturing a resin tube having a structure, the purpose is to ensure that the adhesion between the two layers can be made sufficiently strong without any special adhesion treatment.

[0007]

In order to solve the above problems, in the present invention, a resin having a two-layer structure in which a second layer having a predetermined thickness is laminated outside a first layer made of a fluororesin. In a tube, the second layer is a fluororubber segment
100 parts by weight of the soft fluororesin obtained by graft-copolymerizing the fluororesin segment is added to 0 parts of the fluororesin.
To 100 parts by weight and 30 to 170 parts by weight of a polyamide resin are mixed together, and the second layer and the first layer are formed by coextrusion molding. A resin tube is the main point.

The present invention also includes a first layer made of a fluororesin, and a second layer positioned outside the first layer,
A resin tube having a three-layer structure in which a third layer made of a polyamide resin positioned outside the second layer is laminated is formed, and the second layer is attached to the fluororubber segment.
0 to 1 of the fluororesin is added to 100 parts by weight of the soft fluororesin obtained by graft-copolymerizing the base resin segment.
It is formed from a resin material containing 100 parts by weight of polyamide resin and 30 to 170 parts by weight of a polyamide resin, and the second layer and the first and third layers are coextruded. A resin tube for fuel piping is also included in the gist of the invention.

[0009]

[Operation / Effect] In summary, in the resin tube according to the present invention, the tube thickness required to obtain sufficient pressure resistance is the second layer located outside the first layer, and the second layer provided outside the first layer. Since it can be ensured by three layers, the first layer made of a fluororesin may be formed to have a minimum thickness that can obtain a sufficient fuel barrier property. Therefore, the amount of fluororesin used can be effectively reduced, and the cost of the tube can be advantageously reduced.

Further, according to the present invention, the second layer in contact with the first layer made of the fluororesin is formed of a special resin blend material prepared by blending the soft fluororesin, the fluororesin and the polyamide resin. Only by coextruding the layers of the laminated tube can the layers be adhered to each other well. Therefore, a special bonding process is not required, and bonding is performed at the same time as molding, and the manufacturing process can be greatly simplified as compared with the conventional method.

A resin blend containing a soft fluororesin or a fluororesin is provided outside the second layer so that a third layer made of a polyamide resin is further provided, and the tube thickness is ensured by the third layer. If the second layer made of the material is also formed to be thin, it is possible to advantageously further reduce the cost.

[Specific configuration]

In the present invention, the fluororesin forming the first layer and the polyamide resin forming the third layer are not special ones, and various known ones can be used. The one suitable for the desired tube performance is appropriately selected and used.

For example, as the fluororesin, polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (CTFE), a copolymer of hexafluoropropylene and tetrafluoroethylene (FEP), fluorinated alkoxyethylene resin (PFA). , Ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-polychlorotrifluoroethylene copolymer (ECTF
E) etc. can be mentioned. As the polyamide resin, any known polyamide resin may be used regardless of whether it is an aliphatic type or an aromatic type, a lactam polymer, a diamine / dicarboxylic acid condensate, an amino acid polymer, and these. Among the copolymers and blends of
It is appropriately selected and used. In addition, specifically, nylon 6, nylon 66, nylon 610, nylon 61
2, nylon 11, nylon 12, etc. can be mentioned.

Thus, the second layer is made of soft fluororesin 10
It is formed of a specific resin blend material in which 0 to 100 parts by weight of a fluororesin and 30 to 170 parts by weight of a polyamide resin are mixed with 0 parts by weight. The fluororesin and polyamide resin blended in the resin blend material are not special ones, and a suitable one is selected from the various known fluororesin and polyamide resins as described above.

By the way, the soft fluororesin blended in such a resin blend material is a fluororubber segment graft-copolymerized with a fluororesin segment.

More specifically, the fluororubber segment is, for example, a copolymer of vinylidene fluoride and hexafluoropropene, a copolymer of vinylidene fluoride, hexafluoropropene and tetrafluoroethylene, vinylidene fluoride and chloro. A copolymer of trifluoroethylene,
Examples thereof include a copolymer of tetrafluoroethylene and propylene, a copolymer of tetrafluoroethylene and fluorinated vinyl ether, and the like.

A monomer having a double bond and a peroxy group is introduced into the molecular chain of these fluororubber segments to provide a polymerization initiation point for graft-copolymerizing the fluororesin segment. Will be done. Specific examples of such a monomer having a double bond and a peroxy group include t-butylperoxyallylcarbonate, n-butylperoxyallylcarbonate, pentaneperoxyallylcarbonate,
There are t-butylperoxymethacrylate, t-butylperoxyacrylate, di (t-butylperoxy) fumarate and the like, which can be introduced by being present at the same time when forming the fluororubber segment.

On the other hand, examples of the fluororesin segment to be graft-copolymerized with the fluororubber segment include vinylidene fluoride, a copolymer of ethylene and tetrafluoroethylene, and a copolymer of ethylene and chlorotrifluoroethylene. Examples thereof include polymers, chlorotrifluoroethylene, copolymers of tetrafluoroethylene and hexafluoropropene, copolymers of tetrafluoroethylene and fluorinated vinyl ether, and various other known materials can be used. . In addition,
In order to obtain good adhesion between the first layer and the second layer, and to ensure that the extrusion temperatures of the first and second layers are about the same (if the extrusion temperatures are too different, the same crosshead However, it is preferable to use the same fluororesin as that used for the first layer. Of course, if the adhesiveness and the extrusion processing temperature condition are satisfied, the same fluororesin may be selected.

Then, the fluororubber segment and the fluororesin segment are mixed in a predetermined ratio and graft-copolymerized according to a usual polymerization method, whereby the desired soft fluororesin can be obtained. , Such a soft fluororesin is blended with the fluororesin and the polyamide resin in consideration of adhesiveness with the first layer and the third layer, extrusion processability, and cost to form the second layer. The resin blend body is prepared.

Among them, the fluororesin is mainly added to enhance the adhesiveness with the first layer, and when the soft fluororesin has sufficient adhesiveness with the first layer. In particular, it is not necessary to mix. However, when compounded in an amount exceeding 100 parts by weight with respect to 100 parts by weight of the soft fluororesin, the cost will remarkably increase, so the fluororesin is compounded in the range of 0 to 100 parts by weight.

The polyamide resin is added in a proportion of 30 to 170 parts by weight with respect to 100 parts by weight of the soft fluororesin. This is because if the amount of the polyamide resin compounded is less than 30 parts by weight, the extrusion processability becomes poor and the adhesion with the third layer becomes poor, and if it exceeds 170 parts by weight, the adhesion with the first layer becomes poor. This is because the sex becomes worse. The soft fluororesin, the fluororesin and the polyamide resin may be blended in a specific manner according to an ordinary method. After the dry blending, the pellets may be pelletized by a single-screw or twin-screw extruder.

In the present invention, the thus prepared resin blend material as the forming material for the second layer, the fluororesin as the forming material for the first layer, and the polyamide resin as the forming material for the third layer are prepared. The combination must be selected so that coextrusion can be performed, and those having melting temperatures close to each other will be selected. Thereby, a resin tube having a two-layer structure in which a first layer made of a fluororesin and a second layer made of a resin blend are laminated by a usual coextrusion molding method, or such a first layer and a second layer It is possible to obtain a resin tube having a three-layer structure formed by further laminating a third layer made of a polyamide resin on the layer.
Moreover, in such a tube, the layers can be firmly bonded only by performing coextrusion molding.

The thickness of each layer of the laminated resin tube is appropriately determined according to the characteristics of each resin material and the desired fuel barrier property and cost. In the case of tubes,
The first layer is about 0.01mm-0.5mm, the second layer is 0.5mm
It is about 2.0 mm. In the case of a three-layer tube, the first layer is usually about 0.01 mm to 0.5 mm, the second layer is about 0.01 mm to 0.5 mm, and the third layer is about 0.2 mm.
About 2.0 mm is preferable. When a third layer made of polyamide resin is provided to form a resin tube having a three-layer structure, the first layer made of fluororesin and the fluororesin are arranged so that the tube thickness is ensured by the third layer. By forming the second layer made of a resin blend material containing the as thin as possible, it is possible to further reduce the cost.

Further, the resin tube of the two-layer structure or the three-layer structure according to the present invention is covered with a solid material or a foam material such as a rubber material, a soft fluororesin, or a thermoplastic elastomer on the outer side of 0.5 mm to 2 mm. You may make it provide the protective layer of about thickness. In that case, an adhesive is applied between the protective layer and the resin tube as needed.

As described above, according to the present invention, the layers of the laminated resin tube are co-extruded to form good adhesion between the layers, even though the layer of fluororesin having poor adhesion is included. Therefore, no special adhesion treatment is required. Therefore, by stacking a layer made of a low-cost resin blend or a polyamide resin on a thin layer made of a fluororesin having a high fuel barrier property, a resin tube having a sufficient tube thickness can be formed without interposing the bonding step. Since it has become possible to manufacture it easily, it is possible to manufacture with high productivity a fuel piping tube that is excellent in lightness, rust prevention, fuel barrier properties, and that is cost-satisfactory. It has become possible.

[0026]

EXAMPLES Some examples of the present invention will be shown below to clarify the present invention in more detail. However, the present invention is not limited by the description of such examples. Needless to say, it is not something to receive. Further, in addition to the following specific examples, in addition to the following embodiments, the present invention includes various modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention.
It should be understood that modifications, improvements, etc. may be made.

First, according to the layer structure shown in Table 1 below, a tube having a three-layer structure in which a first layer made of a fluororesin, a second layer made of a resin blend material, and a third layer made of a polyamide resin are laminated (implemented) Examples No. 1 to 5) were produced by coextrusion, and as comparative examples, tubes having the second layer removed (Comparative Examples Nos. 1 and 3) and a tube having a second layer made of a soft fluororesin. (Comparative Example N
O. 2) was made by coextrusion. Each tube had an inner diameter of 6 mmφ and an outer diameter of 8 mmφ, and in the case of a three-layer structure, the first layer was 0.3 mm, the second layer was 0.3 mm, and the third layer was 0.3 mm. In the case of a double layer structure with a thickness of 4 mm, the first layer is 0.5 mm and the third layer is 0.5 mm.
It was formed with a thick wall.

Then, a test piece having a width of 1 inch was taken from each of the obtained tubes, and the test piece of JIS-K-6301 18 was used.
The peel strength was examined according to the 0 degree peel test, and the results are also shown in Table 1. The abbreviations in Table 1 are as follows. F-1: A product obtained by graft-polymerizing vinylidene fluoride as a fluororesin segment on a fluororubber copolymerization segment composed of vinylidene fluoride, hexafluoropropene and t-butylperoxyallyl carbonate. F-2: Fluororubber copolymer segment consisting of vinylidene fluoride, chlorotrifluoroethylene and t-butylperoxyallyl carbonate, and chlorotrifluoroethylene as a fluororesin segment. PVDF: Polyvinylidene fluoride ECTFE: Copolymer of ethylene and polychlorotrifluoroethylene PA12 acceptable: Nylon 12, plasticizer blended PA11 acceptable: Nylon 11, plasticizer blended PA12 none: Nylon 12, no plasticizer blended

[0029]

[Table 1]

As is clear from the results shown in Table 1, a tube in which a third layer made of a polyamide resin is directly laminated on a first layer made of a fluororesin (Comparative Examples No. 1 and 3).
In, the peeling strength was remarkably low as less than 0.5, and the adhesive was adhered only to a close degree. Further, even in the tube in which the first layer and the third layer are laminated via the second layer made of soft fluororesin (Comparative Example No. 2), the peel strength is hardly improved.

On the other hand, between the first layer and the third layer,
Tubes laminated with a second layer consisting of a resin blend prepared according to the invention (Examples Nos. 1-5)
Then, it is understood that all of them show extremely high peel strength, and it is understood that no special bonding step is required.

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Claims (2)

[Claims] 1. A resin tube having a two-layer structure in which a second layer having a predetermined thickness is laminated on the outside of a first layer made of fluororesin , and the second layer is a fluororubber segment.
100 parts by weight of the soft fluororesin obtained by graft-copolymerizing the fluororesin segment is added to 0 parts of the fluororesin.
To 100 parts by weight and 30 to 170 parts by weight of a polyamide resin are mixed together, and the second layer and the first layer are formed by coextrusion molding. Resin tube. 2. A laminate of a first layer made of a fluororesin, a second layer positioned outside the first layer, and a third layer made of a polyamide resin positioned outside the second layer. A resin tube having a three-layer structure formed, wherein the second layer is a fluororubber segment and a fluororesin segment.
100 of soft fluororesin obtained by graft-copolymerizing
It is formed from a resin material in which 0 to 100 parts by weight of a fluororesin and 30 to 170 parts by weight of a polyamide resin are mixed with respect to parts by weight, and the second layer and the first layer and the third layer are A resin tube for fuel piping, characterized by being co-extruded.