JP2003246028A - Fuel parts - Google Patents

Abstract

(57) [Summary] [Problem] Multilayer structure with excellent fuel permeation resistance, small decrease in interlayer adhesion strength even when in contact with gasoline or gasohol, no delamination or cracking, and excellent creep resistance Provide fuel parts. A modified high density polyethylene obtained by grafting an unsaturated carboxylic acid or a derivative thereof into a fuel part attached to a resin fuel tank, wherein an inner layer (A) in contact with the fuel and an outer layer (C) in contact with the outside air are grafted And the intermediate layer (B) has a multilayer structure made of polyamide containing 3 to 27% by weight of a plate-like inorganic filler.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fuel component such as a valve cover attached to a resin fuel tank. More specifically, the present invention relates to a fuel element having a multi-layered structure, which has excellent fuel permeation resistance, has a small decrease in interlayer adhesion strength even when contacted with gasoline or gasohol, does not cause delamination or cracking, and has excellent creep resistance.

[0002]

2. Description of the Related Art Conventionally, for safety and environmental measures, it has been demanded to reduce the amount of fuel volatilized from a wall or a connecting portion of a fuel tank for automobiles or accessories. For example, a fuel tank made of high-density polyethylene is a multilayer blow-molded product having a polyamide having a high gasoline barrier property or an ethylene-vinyl alcohol copolymer as an inner layer to prevent gasoline from evaporating into the atmosphere. However, conventionally, fuel components such as valve covers for connecting fluid tubes attached to high-density polyethylene fuel tanks are made of the same material as the fuel tanks in order to obtain sufficient adhesive strength with the fuel tanks. It was manufactured in the above and was welded to the fuel tank by the hot plate welding method or the like. Therefore, the amount of permeation from the fuel parts made of high-density polyethylene, which is inferior in fuel permeability, is large, which has been an obstacle to reducing the amount of volatilization from the entire fuel parts.

Therefore, it may be possible to manufacture the fuel part from polyamide, which is much more excellent in gasoline permeability than polyethylene. However, since polyethylene and polyamide originally have poor adhesiveness, the fuel tank and the fuel part are welded to each other. I can't. For this reason, it was considered that the fuel parts had a multi-layer structure consisting of polyethylene layer / adhesive layer / polyamide layer, but when contacting with gasoline or gasohol, swelling of the polyethylene layer and adhesive layer caused interlayer adhesion between the polyethylene layer and polyamide layer. There has been a problem that the strength is reduced and delamination and cracking occur.

On the other hand, Japanese Patent No. 2715870 discloses that
As a resin joint for joining a flexible conduit to a polyethylene tank, a part of the polyethylene joint is made of glass fiber reinforced polyamide resin, and fuel leakage due to the creep of polyethylene that occurs at the tube connection part by a coupler etc. It is described to prevent this.

Polyamide resins are generally considered to have low gasoline permeability, little swelling property to gasoline, and no deterioration of physical properties or dimensional change. However, in recent years, there are many examples of using gasohol in which 10 to 15% by weight of gasoline is mixed with methanol or ethanol. In a direct fuel injection engine, there is a partial return of fuel, and the fuel temperature in the tank is 60%. Since the temperature rises from ℃ to 80 ℃, polyamide will swell in methanol and ethanol in gasohol at such high use temperature, and especially the elastic modulus in the direction perpendicular to the orientation-strengthening direction of the glass fiber will significantly decrease and creep phenomenon will occur. Was found to happen. This indicates that neither polyamide alone nor fiber reinforced polyamide can be used in structures contacting gasohol fuel.

[0006]

In view of the above problems, the present invention suppresses fuel evaporating from fuel parts such as a valve cover attached to a polyethylene fuel tank, and easily adheres to the polyethylene fuel tank. Can be joined,
Another object of the present invention is to provide a fuel component that retains excellent interlayer adhesion even after contact with gasoline or gasohol, and that also has excellent creep resistance.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, have made a modified high-density polyethylene layer as an inner layer (A) in contact with fuel and an outer layer (B).
Is a polyamide layer containing a plate-like inorganic filler, or an inner layer (A) in contact with fuel and an outer layer (C) in contact with the outside air are modified high-density polyethylene layers, and an intermediate layer (B) is It has been found that the above object can be achieved by using a multilayer structure having a polyamide layer containing a plate-like crystal inorganic filler.

That is, the present invention is a fuel component attached to a resin fuel tank, wherein the inner layer (A) is made of high-density polyethylene modified with unsaturated carboxylic acid or its derivative, and the outer layer (B) is a plate. The present invention relates to a fuel component having a multi-layered structure made of a polyamide resin containing 3 to 27% by weight of a crystalline inorganic filler. Further, the present invention is a fuel component attached to a resin fuel tank,
The inner layer (A) in contact with the fuel and the outer layer (C) in contact with the outside air are composed of modified high-density polyethylene obtained by grafting an unsaturated carboxylic acid or its derivative, and the intermediate layer (B) is composed of a plate-like crystal inorganic filler. The present invention relates to a fuel part having a multi-layer structure made of polyamide containing about 27 wt%.

Inner layer (A) and outer layer (C) in the present invention
Is a modified high-density polyethylene obtained by grafting an unsaturated carboxylic acid or a derivative thereof on the high-density polyethylene. The density of modified high-density polyethylene is 0.9
It is preferably 35 to 0.955 g / cm ³ .

As the unsaturated carboxylic acid or its derivative to be graft-polymerized, acrylic acid, methacrylic acid,
Ethacrylic acid, maleic acid, fumaric acid, itaconic acid,
Unsaturated carboxylic acids such as citraconic acid and nadic acid or derivatives thereof, such as acid halides, amides, imides,
Examples thereof include anhydrides and esters. Specific examples of the derivative include maleenyl chloride, maleimide, maleic anhydride,
Examples include monomethyl maleate and dimethyl maleate. Among these, unsaturated dicarboxylic acids or their anhydrides are preferable, and maleic acid, nadic acid or their acid anhydrides are particularly preferably used. Also,
The modified high-density polyethylene is a known production method, for example,
A method of reacting unmodified high-density polyethylene and an unsaturated carboxylic acid in a molten state, a method of reacting in a solution state,
It can be produced by any of a method of reacting in a slurry state, a method of reacting in a gas phase state and the like.

As the polyamide of the outer layer (B) or the intermediate layer (B) of the present invention, an aliphatic polyamide resin composed of an aliphatic diamine and an aliphatic dicarboxylic acid, or an lactam or an aminocarboxylic acid, or an aromatic monomer. A crystalline semi-aromatic polyamide resin containing one or more components is used.

As the monomer component of the aliphatic polyamide resin, an aliphatic diamine having 4 to 12 carbon atoms and 6 to 1 carbon atoms are used.
Examples thereof include aliphatic dicarboxylic acids having 2 carbon atoms, lactams having 6 to 12 carbon atoms, and aminocarboxylic acids having 6 to 12 carbon atoms. Specific examples of the aliphatic diamine include tetramethylenediamine, hexamethylenediamine, octamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, and the like, and specific examples of the aliphatic dicarboxylic acid include adipic acid. , Heptane dicarboxylic acid, octane dicarboxylic acid, nonane dicarboxylic acid, undecane dicarboxylic acid, dodecane dicarboxylic acid and the like, a preferred combination of aliphatic diamine and aliphatic dicarboxylic acid is an equimolar salt of hexamethylene diamine and adipic acid. . Specific examples of lactams include α
-Pyrrolidone, ε-caprolactam, ω-laurolactam, ε-enanthlactam and the like, and specific examples of the aminocarboxylic acid include 6-aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid and 12-amino. Examples thereof include dodecanoic acid, and 6-aminocaproic acid, 12-aminododecanoic acid, ε-caprolactam and laurolactam are preferable. The aliphatic polyamide-forming monomer can be used not only as a single component but also as a mixture of two or more components.

Specific examples of the aliphatic polyamide resin formed from these monomer components include nylon 6, nylon 66, nylon 11 and nylon 12, which may be homopolymers or copolymers of two or more kinds.
In particular, nylon 6 and nylon 66, which have the lowest gasoline permeability, are most preferably used.

As the crystalline semi-aromatic polyamide resin containing at least one aromatic monomer component, one aromatic monomer component such as an aromatic dicarboxylic acid component such as terephthalic acid, isophthalic acid or naphthalene dicarboxylic acid is used. Examples thereof include copolyamide resins containing at least one species. Preferably, it contains one or more aromatic monomer components and has a melting point of 26.
A crystalline semi-aromatic copolymerized polyamide resin having a temperature of 0 ° C. or higher and lower than 320 ° C., more preferably a crystalline semi-aromatic copolymerization resin having one or more aromatic monomer components and a melting point of 290 ° C. or higher and lower than 316 ° C. It is a polyamide resin. Preferred combinations of crystalline semi-aromatic copolyamide resins containing one or more aromatic monomer components include equimolar salts of aliphatic diamine and aliphatic dicarboxylic acid, and equimolar salts of aliphatic diamine and aromatic dicarboxylic acid. And / or a crystalline copolyamide resin comprising an aliphatic polyamide-forming monomer.

Here, the aliphatic diamine has 4 to 12 carbon atoms.
Examples of the aliphatic diamine include tetramethylenediamine, hexamethylenediamine, octamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, and the like. The aliphatic dicarboxylic acid is an aliphatic dicarboxylic acid having 6 to 12 carbon atoms, and examples thereof include adipic acid, heptanedicarboxylic acid, octanedicarboxylic acid, nonanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid and the like. A preferred combination is an equimolar salt of hexamethylenediamine and adipic acid.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid, and a preferable combination is an equimolar salt of hexamethylenediamine and terephthalic acid.

The aliphatic forming monomer has 6 to 6 carbon atoms.
12 aminocarboxylic acids and lactams having 6 to 12 carbon atoms, such as 6-aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, α-pyrrolidone, ε-caprolactam, laurolactam , Ε-enanthlactam and the like, 6-
Aminocaproic acid, 12-aminododecanoic acid, ε-caprolactam and laurolactam are preferred. The aliphatic polyamide-forming monomer can be used not only as a single component but also as a mixture of two or more components.

The amounts of these used are 30 to 70% by weight of equimolar salt of hexamethylenediamine and adipic acid, 70 to 30% by weight of equimolar salt of hexamethylenediamine and terephthalic acid, and 0 to 15% by weight of aliphatic polyamide-forming monomer. %, Preferably 35 to 55% by weight of equimolar salt of hexamethylenediamine and adipic acid, 65 to 45% by weight of equimolar salt of hexamethylenediamine and terephthalic acid, and 0 to 10% by weight of aliphatic polyamide forming monomer. is there.

The degree of polymerization of the polyamide used in the present invention is not particularly limited, but 1 g of the polymer is added to 100 m of 96% concentrated sulfuric acid.
and a relative viscosity measured at 25 ° C. of 1.8-5.
It is preferably 0, more preferably 2.0 to 3.
It is 0. If the relative viscosity is higher than the upper limit of the above numerical value, the workability is significantly impaired, and if it is lower than the lower limit, the mechanical strength is lowered, which is not preferable.

The polyamide of the present invention preferably has a concentration of amino end groups higher than that of carboxyl end groups. Also, the concentration of amino end groups is 5 per kg of polymer.
It is desirable that the amount is 0 meq or more, preferably 60 meq or more. When the amino terminal group concentration is excessive, when it is welded to a polyolefin resin modified with an unsaturated carboxylic acid anhydride, the welding strength becomes excellent and excellent fuel resistance is exhibited.

The method for producing a polyamide resin according to the present invention, in which the amino end group concentration is higher than the carboxyl end group concentration, comprises:
Although it is not particularly limited, it can be obtained by incorporating a diamine compound at the time of polymerization or when the composition is extrusion-kneaded after the completion of the polymerization. If it is produced during melt polymerization, a method of polymerizing by adding an excess of a diamine monomer at the time of charging the raw material, a method of polymerizing by adding a raw material monomer and a diamine compound other than the raw material monomer at the time of charging the raw material, and polymerizing a polyamide having a predetermined molecular weight After that, a method is used in which the diamine compound is added immediately before the polymer is extracted from the polymerization tank so as to achieve the desired end group concentration balance. If it is produced after the polymerization, a method in which the polyamide resin after the polymerization and the diamine compound are melt-kneaded so as to achieve the desired end group concentration balance is used.

Specific examples of the diamine compound include, in addition to those used as a monomer of the above-mentioned polyamide resin, an aliphatic diamine such as methylenediamine, ethylenediamine and trimethylenediamine, and an aromatic diamine such as naphthalenediamine and metaxylylenediamine. Diamine is used, preferably hexamethylenediamine, dodecamethylenediamine, and metaxylylenediamine.

The polyamide of the outer layer (B) or the intermediate layer (B) of the present invention contains the plate-like crystal inorganic filler in an amount of 3 to 27% by weight. As the plate-like crystal inorganic filler, fine powder talc or fine powder mica is preferably used, and particularly, the average particle diameter is 0.5 to 10 μm.
m, and the aspect ratio (that is, the diameter / thickness ratio of the flat plate) is preferably 5 times or more.

The content of the plate-like crystal inorganic filler is 3 to 27% by weight, preferably 15 to 25% by weight. If it is less than 3% by weight, the effect of improving the T peel strength cannot be obtained. On the other hand, if it exceeds 27% by weight, the polyamide layer becomes brittle and the interfacial welding strength is high, but the polyamide layer is cohesively broken, which is not preferable.

In the fuel part of the present invention, by using the modified high-density polyethylene in the inner layer (A) that is in direct contact with gasoline, it can be welded to a multi-layer fuel tank made of high-density polyethylene, and can be used for alcohol fuels such as methanol. Excellent barrier property. When modified high density polyethylene is used for the outer layer (C) exposed to the outside air, it has excellent calcium chloride resistance. Further, the outer layer (B) or the intermediate layer (B) has a multi-layer structure using polyamide containing a plate-like crystal inorganic filler. The reason for this is that polyamide cannot avoid swelling in alcohol-based fuels such as methanol at high operating temperatures, and as a result, the swelling ratios of polyamide and modified high-density polyethylene differ significantly. This is because the interfacial peeling progresses. That is, by having a multilayer structure of a polyamide layer and a polyethylene layer, alcohol such as methanol is blocked by the polyethylene layer of the inner layer (A), and gasoline that diffuses and permeates the polyethylene layer contains a plate-like crystal inorganic filler. By blocking with the polyamide layer (B), in addition to the gasoline-blocking property of ordinary polyamide, the gasoline-blocking effect due to the orientation of the plate-like crystals is superimposed to effectively reduce the gasoline transpiration rate. And

Furthermore, by dispersing plate-like fine powder crystals of talc or the like in polyamide, not only the initial inter-layer adhesion can be achieved in the welded material between modified high-density polyethylene and polyamide, which has low welding strength and cannot withstand practical use. It has become possible to maintain the interlaminar adhesive strength after soaking in gasoline. That is, in a multi-layer fuel valve, by keeping the fuel swelling ratio of the talc mixed polyamide layer equal to the gasoline swelling ratio of the modified high-density polyethylene within the possible range or within the shear fracture limit of the material, even if it comes into contact with gasoline. Utilizing the fact that the characteristic that the strength is less decreased is obtained.
This improves the interlayer adhesion strength between the polyethylene layer and the polyamide layer in a multilayer injection-molded product, and further reduces the gasoline permeation rate due to the plane orientation of plate crystals such as talc. It is possible to obtain a fuel component that is free from such problems and has excellent creep resistance. The reason for using high-density modified polyethylene here is that the fuel tank is a multi-layer blow-molded product of high-density polyethylene, the resin valve can be easily welded to the fuel tank, and the dimension due to swelling of polyethylene with gasoline for a long period of time. This is to suppress the change to a minimum and prevent peeling, cracking and the like due to shear deformation of the welded portion.

In the examples of the present invention, nylon 6 having a high terminal amino group concentration mixed with talc and maleic acid-modified high-density polyethylene have the same T peel strength as nylon 6 having no talc mixed and maleic acid-modified high density polyethylene. The reason for the marked improvement compared with the case of the polyethylene weld deposit is not clear, but it is considered that there is some interaction between talc and maleic acid-modified high-density polyethylene.

The fuel part of the present invention, in which the inner layer (A) is composed of modified high-density polyethylene and the outer layer (B) is composed of polyamide resin, the modified high-density polyethylene is molded and then the polyamide resin is injection-molded to obtain both molded products. Is performed by welding.

Specific examples of the welding method include a vibration welding method, an injection welding method such as die slide injection (DSI), die rotary injection (DRI) and two-color molding, an ultrasonic welding method, a spin welding method, a hot plate welding method. , A heat wire welding method, a laser welding method, a high frequency induction heating welding method, and the like.

It is desirable that the temperature of the molding resin at the time of welding by the injection welding method such as DSI, DRI, and two-color molding is 250 ° C to 320 ° C, preferably 270 ° C to 300 ° C. The mold temperature at that time is 30 ° C to 120 ° C, preferably 50 ° C to 100 ° C.
Is desirable.

The fuel component of the present invention, in which the inner layer (A) and the outer layer (C) are composed of modified high-density polyethylene and the intermediate layer (B) is composed of polyamide resin, can be molded by sandwich molding or the like. In the sandwich molding, a usual multi-layer molding method can be used in which the modified high-density polyethylene molten resin is partially injected into the mold, and the intermediate layer polyamide is injected before solidification to complete the mold filling.
At the interface between modified polyethylene and polyamide, the modified polyethylene is melted by the polyamide melt resin that is injected at a higher temperature than the modified polyethylene, and the chemical bond between the carboxyl group of the modified polyethylene and the terminal amino group of the polyamide resin bonds to a chemical bond. It is firmly welded at the interface.

Each of the resins constituting the fuel component of the present invention contains a heat-resistant agent, a weather-resistant agent, a crystallization accelerator, a mold release agent, an antistatic agent, a flame retardant, and a flame retardant auxiliary agent within the range not impairing the object of the present invention. Additives known per se such as pigments, pigments, lubricants and foaming agents can be added.

More specifically, as the heat-resistant agent, hindered phenols, phosphites, thioethers,
Examples thereof include copper halides, which can be used alone or in combination. Examples of the weather resistance agent include hindered amines and salicylates, which can be used alone or in combination. Examples of the crystallization accelerator include low molecular weight polyamides, higher fatty acids, higher fatty acid esters and higher aliphatic alcohols, which can be used alone or in combination. Examples of the release agent include fatty acid metal salts, fatty acid amides, and various waxes, which may be used alone or in combination. Examples of the antistatic agent include aliphatic alcohols, aliphatic alcohol esters and higher fatty acid esters, which may be used alone or in combination. As the flame retardant, metal hydroxide such as magnesium hydroxide, phosphorus, ammonium phosphate, ammonium polyphosphate, melamine cyanurate, ethylene dimelamine dicyanurate, potassium nitrate, brominated epoxy compound, brominated polycarbonate compound, brominated Examples thereof include polystyrene compounds, tetrabromobenzyl polyacrylate, tribromophenol polycondensates, polybromobiphenyl ethers and chlorine-based flame retardants, which can be used alone or in combination.

Other thermoplastic resins may be added to the polyamide of the outer layer or the intermediate layer (B) of the present invention within the range not impairing the object of the present invention. Examples of thermoplastic resins used in combination include general-purpose resin materials such as polyethylene, polypropylene, polystyrene, ABS resin, AS resin, and acrylic resin, polycarbonate, polyphenylene oxide,
Examples thereof include polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, and other high heat resistant resins. Particularly when polyethylene or polypropylene is used in combination, it is desirable to use those modified with maleic anhydride, a glycidyl group-containing monomer or the like.

The fuel parts of the present invention include parts such as valves attached to the fuel tank, fuel hose joints, canister connecting nozzles and separators.

FIG. 1 shows an example of a resin valve cover as an embodiment of the present invention. This resin valve cover is welded to a polyethylene fuel tank for automobiles that use gasoline or gasohol to permanently join flexible fluid tubes without leaks or cracks, and has low fuel vaporization resistance and resistance. It also has excellent creep properties.

[0037]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The physical properties of the molded articles in the examples and comparative examples were measured as follows.

[Sample preparation and test method] Talc mixed polyamide 6 resin; using a twin-screw kneader (TEX30XSST) manufactured by Japan Steel Works, Ltd., kneading temperature 2
50 ° C., screw rotation speed 250 RPM, screw was 2 threads, L / D = 40, and a weight feeder was used for each component so as to obtain a predetermined material composition. The strand was water-cooled to obtain a pelletized talc-mixed polyamide, which was further vacuum dried at 80 ° C. for 48 hours. -Glass fiber mixed polyamide 6 resin; using a twin-screw kneader (TEX30XSST) manufactured by Japan Steel Works, kneading temperature 250 ° C, screw rotation speed 200 rpm, screw 2 rows, L / T = 40, polyamide is weight A predetermined amount was put into the hopper supply port with a feeder, and the glass fiber was made by Nippon Electric Glass Co., Ltd. 03T275H, cut length 10 mm, fiber diameter 1
0 μm) was charged by a side feeder. The strand was water-cooled to obtain a pellet-shaped glass fiber-mixed polyamide. Further, vacuum drying was performed at 80 ° C. for 48 hours.

-ASTM No. 1 dumbbell pull test; A
STM D882-91 * T peel strength sample and measurement; 70 mm x 70 mm x 3
A maleic acid-modified high-density polyethylene was injection-molded at 230 ° C. at a mold temperature of 40 ° C. using a mold of mm. Next, 70 mm x 70 mm x 5 mm mold (mold temperature 80 ° C)
To obtain the chuck margin for the tensile test,
Adhere a 30 mm x 70 mm polyimide adhesive film to the end of the modified high-density polyethylene piece prepared in advance, and insert it so that the adhesive film is on the gate side of the mold and on the welding surface side. Polyamide 6 resin or talc mixed polyamide 6 resin 300
Ejected at ° C. The obtained sample has a polyethylene layer thickness of 3
mm, the thickness of the polyamide layer is 2 mm, and both surfaces are welded. This sample was cut in parallel with the injection direction at intervals of 10 mm, the polyimide film portion was opened, and a T-peel sample was obtained as a gripping margin of a chuck of a tensile tester. The T peeling speed was measured at 20 mm / min.

Fuel dipping method: A stainless pressure resistant container was dipped in synthetic gasoline (Fuel C) or synthetic gasoline mixed with methanol at 60 ° C. for 2 weeks, and immediately used as a tensile test and T peel test sample. Immersion condition 1; using Fuel C as the immersion liquid, 6
Immersion condition 2 at 0 ° C. for 2 weeks; methanol mixed gasoline as immersion liquid, 60 ° C. for 2 weeks Immersion, Fuel C; 50% by volume of toluene + 50 isooctane
Volume% methanol mixed gasoline; Fuel C85 volume% + methanol 15 volume%.

[Polyamide Resin Used] Polyamide 6A; Nylon 6 manufactured by Ube Industries, Ltd., trade name 1013A, amino terminal group concentration 97 meq / kg, carboxyl terminal group concentration 25 meq / kg Polyamide 6B; Ube Kosan ( Nylon 6, brand name 1013B, amino end group concentration 46 meq / kg, carboxyl end group concentration 65 meq / kg [modified high density polyethylene used] density 0.95 g / cm
^3. Maleic acid-modified high-density polyethylene (manufactured by Nippon Oriolefin Co., Ltd., trade name ER403A) with a maleic anhydride concentration of 19.2 milliequivalents / kg

Example 1 Using a maleic acid-modified high density polyethylene (manufactured by Nippon Oriolefin Co., Ltd., trade name ER403A), ASTM1 was used.
No. dumbbell mold, mold temperature 40 ℃, cylinder temperature 23
Ejected at 0 ° C. The No. 1 dumbbell-shaped modified polyethylene obtained was cut at the central position, and the polyamide 6A (manufactured by Ube Industries, Ltd., product First name 1013A) 9
Talc mixed nylon prepared by mixing 0 wt% and 10 wt% of talc powder (manufactured by Fuji Talc Industry Co., Ltd., trade name LSM350: average particle size 4.2 μm) with a biaxial kneader is injected at 300 ° C. Both resins have been welded with
An STM No. 1 dumbbell sample was obtained. The welding strength of this sample and the samples treated under the immersion conditions 1 and 2 were measured by a tensile test. Initial strength is 85.7 MPa,
The immersion condition 1 was 76 MPa, and the immersion condition 2 was 25 MPa.
It was 5 MPa.

Example 2 A sample was prepared in the same manner as in Example 1 except that the talc mixed polyamide used in Example 1 was composed of 80% by weight of polyamide 6A and 20% by weight of talc powder, and the initial welding strength was The welding strength after immersion was determined. Initial welding strength is 91.3
MPa, 76.5 MPa after the immersion condition 1 treatment, and 37.4 MPa after the immersion condition 2 treatment.

Comparative Example 1 A sample was prepared in the same manner as in Example 1 except that polyamide 6A was used and no talc was used, and the initial welding strength and the welding strength after immersion were determined. Initial strength is 84.3MP
a, after the immersion condition 1 treatment, it decreased to 56.1 MPa, and after the immersion condition 2 treatment, it decreased to 11.8 MPa.

Comparative Example 2 A sample was prepared in the same manner as in Example 1 except that the polyamide 6B was used and the system did not contain talc, and the initial welding strength and the welding strength after immersion were determined. Initial strength is 81.3MP
a, immersion condition 1 7.7 MPa after treatment, immersion condition 2
After the treatment, the pressure dropped to 2.5 MPa.

Comparative Example 3 Instead of talc which is a plate-like crystal, spherical calcium carbonate fine powder having no shape anisotropy (Shiraishi Calcium Co., Ltd.)
Product name, StaVigot 15A: average particle size 0.
15 μm) 10% by weight, polyamide 6A 90% by weight
A sample was prepared in the same manner as in Example 1 except that the polyamide obtained by biaxially kneading was used to determine the initial welding strength and the welding strength after immersion. The initial strength decreased to 80.2 MPa, to 51.5 MPa after the immersion condition 1 treatment, and to 18.8 MPa after the immersion condition 2 treatment.

Comparative Example 4 A sample was prepared in the same manner as in Comparative Example 3 except that 20% by weight of calcium carbonate fine powder and 80% by weight of polyamide 6A were used to determine the initial welding strength and the welding strength after immersion. Initial strength is 81.4 MPa, 66.4 after immersion condition 1 treatment.
MPa, after dipping condition 2 treatment, decreased to 16.7 MPa. The results of Examples 1 and 2 and Comparative Examples 1 to 4 are summarized in Table 1.
Shown in.

Example 3 80% by weight of polyamide 6A and 20% by weight of talc powder
A sample for T-peel test was prepared using the talc-mixed polyamide containing the talc mixed polyamide, and the interlayer adhesion strength between the maleic anhydride-modified high-density polyethylene and the polyamide was evaluated. The inner layer of the fuel component is acid-modified high-density polyethylene, and in actual use, methanol and the like in gasohol are blocked by the polyethylene layer of the inner layer, so it is difficult to reach the polyamide layer. Therefore, as a strength reduction test by the fuel of welding strength, it was evaluated using immersion condition 1 of Fuel C containing no methanol as the immersion condition. The results are shown in Table 2. The T-peel strength of polyamide 6A containing 20% by weight of talc fine powder and maleic acid-modified high-density polyethylene was significantly increased in T-peel strength as compared with polyamide 6A containing no talc. F
There is little decrease in strength even after immersion in uel C.

Comparative Example 5 A sample was prepared in the same manner as in Example 3 except that the polyamide 6A was used and the system did not contain talc, and the interlayer welding strength was evaluated. The results are shown in Table 2. The T peel strength of the polyamide 6A containing no talc and the maleic acid-modified high-density polyethylene was low both in the initial strength and after the immersion condition 1 treatment.

Comparative Example 6 70% by weight of polyamide 6A and 30% by weight of talc powder
A sample was prepared in the same manner as in Example 3 except that the above was used, and the interlayer welding strength was evaluated. The results are shown in Table 2.

Examples 4 to 5 and Comparative Examples 7 to 8 Using a film gate type mold having a cavity of 100 × 100 × 2 mm, a glass fiber mixed polyamide resin and a talc mixed polyamide resin were placed at 250 ° C. Temperature 8
A flat plate was obtained by injection molding at 0 ° C. Fuel C of 60 degrees
After soaking in a fuel containing + 15% by volume of methanol for 2 weeks, the flat plate was cut out in a 10 mm width in the injection direction and a direction perpendicular to the injection direction to obtain a sample for a tensile test. Tensile conditions are ASTM D88
2-91. The results are shown in Table 3.

Comparing the elastic moduli before soaking the synthetic fuel, the glass fiber-mixed polyamide moldings having a filler amount of 20 and 30% have large anisotropy in the injection direction and the direction perpendicular thereto, whereas the filler amount is large. The 20% and 30% talc-mixed polyamide moldings having the same ratio have almost no anisotropy. Looking at the change tendency of the elastic modulus after immersion in fuel, the anisotropy in the injection direction and the direction orthogonal to it expanded further in the glass fiber mixed polyamide molded product, especially the injection in the non-reinforced direction and the decrease in elastic modulus in the direction perpendicular to it. Fierce. On the other hand, the talc-mixed polyamide resin molded product obtained by mixing 20% and 30% talc has almost no anisotropy in elastic modulus even after the immersion in fuel. Moreover, when comparing the elastic moduli in the direction perpendicular to the injection direction with the same amount of filler, the elastic moduli are higher than those of glass fiber-mixed polyamide molded products. This experimental result shows that the glass fiber-mixed nylon resin molded product is easily deformed when external stress is applied in the direction perpendicular to the injection direction by the fuel immersion. On the other hand, the talc-mixed nylon resin molded product maintains almost no anisotropy in the elastic modulus even when immersed in fuel, and also has a higher elastic modulus than the elastic modulus in the direction perpendicular to the injection of the glass fiber mixed molded product. I understand. This result indicates that nylon resin molded products mixed with glass fibers, which are fibrous materials, cannot avoid the anisotropy of mechanical properties and the creep phenomenon caused by the expansion of elastic modulus anisotropy due to fuel immersion. The talc-mixed nylon resin molded product, which is a crystal-like crystal, has almost no anisotropy in mechanical properties even when immersed in fuel, and the elastic modulus in the direction perpendicular to the injection direction is larger than that of the glass fiber mixed product, so it deforms in a specific direction. It can be said that it is a material with high creep resistance without being easy to do.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

EFFECTS OF THE INVENTION According to the present invention, a fuel component for a polyethylene fuel tank, which has an excellent decrease in the welding strength even when it comes into contact with gasoline or gasohol (a mixture of gasoline and alcohol) and has no delamination or cracking, is provided. Can be given.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a resin valve cover according to an embodiment of the present invention.

Continued front page    F-term (reference) 4F100 AA01B AC05B AC10B AK05A                       AK05C AK46B AL04A AL04C                       AL06A BA02 BA03 BA06                       BA07 CA23B GB90 JA13A                       JA13C JD02 JK08 JL11                       YY00A YY00B YY00C

Claims (8)

[Claims] 1. A fuel component attached to a resin fuel tank, wherein an inner layer (A) is made of high-density polyethylene modified with an unsaturated carboxylic acid or its derivative, and an outer layer (B) is a plate-like crystal inorganic filler. A fuel component having a multi-layered structure made of a polyamide resin containing 3 to 27% by weight of a material. 2. A fuel component attached to a resin fuel tank, wherein a modified high density obtained by grafting an unsaturated carboxylic acid or its derivative into an inner layer (A) in contact with fuel and an outer layer (C) in contact with the outside air. A fuel component comprising a polyethylene, wherein the intermediate layer (B) has a multi-layer structure comprising a polyamide resin containing 3 to 27% by weight of a plate-like crystal inorganic filler. 3. The modified high-density polyethylene has a density of 0.9.
35-0.955 g / cm < ³ >, The fuel component of Claim 1 or 2 characterized by the above-mentioned. 4. The polyamide resin has an amino terminal group concentration>
The fuel component according to claim 1 or 2, which has a carboxyl end group concentration. 5. The fuel component according to claim 4, wherein the polyamide resin has an amino terminal group concentration of 50 meq or more per kg of polymer. 6. The fuel component according to claim 1, wherein the plate-like crystal inorganic filler is fine powder talc or fine powder mica. 7. The fuel component is a valve cover for connecting a fluid tube to a resin fuel tank, the valve cover being welded to a pipe-shaped portion for connecting to the fluid tube and the fuel tank. The fuel component according to claim 1 or 2, wherein the fuel component has an end portion for welding. 8. The fuel component according to claim 7, wherein the welding end portion for welding to the fuel tank is a flange.