JP2000345421A - Helmet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a helmet having a light weight and stiffness, and also excellent in impact strength and impact-absorbing property by expansion molding a fiber-reinforced thermoplastic resin using a glass long fiber within a prescribed range of the expansion magnification. SOLUTION: This helmet is produced by introducing a glass fiber bundle having 1-50 μm, preferably 3-30 μm fiber diameter into a die, making it in contact with and impregnated with a thermoplastic resin, e.g. an olefin-based resin such as a polypropylene supplied from an extruder, drawing it out from the die to form a strand, then cutting to pelletize for obtaining a glass fiber- reinforced thermoplastic resin containing 20-80 wt.%, preferably 30-70 wt.% glass long fiber having 2-100 mm, preferably 3-50 mm length in the above thermoplastic resin, and expansion-molding the resin in 1.2-4.0 range of expansion magnification.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helmet, and more particularly, to a helmet that is lightweight, rigid and excellent in impact resistance and shock absorption.

[0002]

2. Description of the Related Art Helmets, which are safety hats for work, include:
Various characteristics such as rigidity, impact resistance, shock absorption, heat resistance, cold resistance, light weight, electric resistance, solvent resistance, and comfort are required depending on the use environment and application. Above all, toughness against impact is a basic characteristic required of a helmet, and if it is added with the property of being lightweight and easy to handle, it can be said to be a more preferable helmet.

Hitherto, materials for forming a helmet include metals, polyethylene, polycarbonate, acrylonitrile-butadiene-styrene copolymer (AB).
Thermoplastic resins such as S) and thermosetting resins such as glass fiber reinforced phenol resin and urethane resin are known. However, although the metal helmet is excellent in impact resistance, it is unsuitable for light movement of an operator due to its weight.

Further, a helmet made of a thermoplastic resin or a glass fiber reinforced thermosetting resin, although lightening is achieved to some extent, is inferior in impact resistance and shock absorption and lacks sufficient impact resistance and the like. Met.

[0005]

SUMMARY OF THE INVENTION The present invention overcomes conventional helmets which satisfy some of the characteristics required for a helmet and are insufficient for other characteristics, and which are required for a helmet. It is an object of the present invention to provide a helmet having various characteristics, in particular, light weight, rigidity, and excellent impact resistance and shock absorption.

[0006]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies focusing on a molding method using a glass fiber reinforced thermoplastic resin as a raw material.
The present inventors have found that the above object can be achieved by expanding and molding a glass fiber reinforced thermoplastic resin, and have completed the present invention based on this finding.

That is, the present invention provides a helmet characterized by being formed by expanding and molding a glass fiber reinforced thermoplastic resin.

[0008]

Embodiments of the present invention will be described below. The present invention is a helmet obtained by expanding a glass fiber reinforced thermoplastic resin as a raw material. The glass fiber for reinforcing the thermoplastic resin used in the present invention is not particularly limited,
E-glass fibers, S-glass fibers and the like are preferably used.

As the glass fiber, a long fiber is preferable, and its length is 2 to 100 mm, preferably 3 to 50 mm. If it is less than 2 mm, impact strength and tensile strength may be insufficient or expansion molding may be difficult. If it is more than 100 mm, poor engraving in a molding machine may occur, which is not desirable.

The glass fibers are preferably arranged in parallel with the glass fiber reinforced thermoplastic resin pellets described below in order to suppress the fiber cutting during plasticization and melting. Although the diameter of the glass fiber is not limited, it is usually 1 to 50 μm, preferably 3 to 30 μm.

When the fiber diameter is less than 1 μm, impregnation of the resin becomes difficult, dispersion becomes insufficient, or the fiber is easily broken, so that sufficient strength as a reinforcing material may not be obtained. If it exceeds, the appearance may be impaired, which is not desirable. The cross-sectional shape of the fiber may be a circle, an ellipse, a rectangle, or the like. The surface of the fiber may be smooth or uneven without any particular problem, and may be linear or crimped.

Further, if desired, a glass fiber whose surface has been treated, for example, a glass fiber which has been subjected to a chemical treatment in order to impart adhesiveness or hydrophilicity can be used.
Examples of the treating agent include silane-based, titanate-based, aluminum-based, chromium-based, zirconium-based, and borane-based coupling agents. Among them, silane-based coupling agents are preferable.

Examples of the silane coupling agent include triethoxysilane, vinyl tris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, N-β- (aminoethyl) -γ
-Aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxy Silane, γ-chloropropyltrimethoxysilane, and the like. Among them, γ-aminopropyltriethoxysilane, N-β-
Aminosilanes such as (aminoethyl) -γ-aminopropyltrimethoxysilane are preferred.

The surface treatment is carried out by a commonly used method, for example, an aqueous solution method, an organic solvent method, or a spray method.
Any method can be adopted. Although there is no particular limitation on the amount of glass fiber to be mixed with the glass fiber reinforced thermoplastic resin, it is usually 20 to 80% by weight, preferably 30 to 70% by weight.
It is. If it is less than 20% by weight, it becomes difficult to produce pellets of the resin, and if it exceeds 80% by weight, the impregnation of the resin may be insufficient, which is not desirable.

As the thermoplastic resin used in the present invention, any resin such as polyolefin resin, polystyrene resin, polyamide resin and polyester resin can be used. Among them, polyolefin resin is preferably used.
Examples of the polyolefin resin include polymers of α-olefins such as ethylene, propylene, butene-1, 3-methylbutene-1, 4-methylbutene-1, and octene-1, copolymers thereof, and other copolymers thereof. It is a copolymer with a possible unsaturated monomer, and examples of the copolymer include a block copolymer, a random copolymer, and a graft copolymer.

Specifically, polyethylene resins such as high density, medium density, low density polyethylene, linear low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polypropylene And polypropylene-based resins such as ethylene-propylene block copolymer and random copolymer, ethylene-propylene-butene-1 copolymer and the like, polybutene-1, poly-4-methylhenten-1 and the like.

These polyolefin resins may be used alone or as a mixture, but a polypropylene resin is particularly preferred. The polypropylene-based resin is not particularly limited, and a wide range of molecular weights can be used. However, from the viewpoint of moldability and appearance, the melt index (MI) [temperature 230 ° C, load 2.16 Kg] is 10 g / 10 min or more. Is preferable, and especially, 30 g / 10 min or more is preferable.

The polyolefin resin includes ethylene-α-olefin-based copolymer rubber, ethylene-α-
Olefin-non-conjugated diene copolymer rubber (for example,
Rubbers such as EPDM), ethylene-aromatic monovinyl compound-non-conjugated diene copolymer rubbers, and hydrogenated products thereof. Further, the polyolefin resin may be a polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof, or may contain the modified polyolefin resin.

The unsaturated carboxylic acid or its derivative-modified polyolefin resin improves the interfacial strength between the glass fiber and the polyolefin resin and greatly improves the tensile strength and the like, and is preferably used in the present invention. As the polyolefin resin to be modified here, modified polyethylene and modified polypropylene are preferred, and modified polypropylene resins are particularly preferred.

The unsaturated carboxylic acid used for the modification includes acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, sorbic acid, mesaconic acid, angelic acid and the like. Also,
Derivatives of these unsaturated carboxylic acids are also used. Examples of the derivatives include acid anhydrides, esters, amides, imides, metal salts and the like. Examples thereof include maleic anhydride, itaconic anhydride, methyl acrylate, methacrylic acid. Examples thereof include methyl acrylate, ethyl acrylate, ethyl acrylate, butyl acrylate, ethyl maleate, acrylamide, maleic amide, sodium acrylate, and sodium methacrylate.

Of these, unsaturated dicarboxylic acids or derivatives thereof are preferred, and maleic anhydride is more preferred. These unsaturated carboxylic acids or derivatives thereof may be used alone or in combination of two or more. The method of denaturation is not particularly limited, and a known method is employed. For example, there are a method in which a polyolefin resin is dissolved in a solvent, an unsaturated carboxylic acid or a derivative thereof and a radical generator are added, and the mixture is heated and stirred, and a method in which the above-mentioned components are supplied to an extruder and graft-copolymerized.

As the modified polyolefin resin, the unsaturated carboxylic acid or its derivative is added in an amount of 0.
The amount is preferably from 01 to 20% by weight, more preferably from 0.02 to 10% by weight. The thermoplastic resin may contain additives such as an antioxidant, a light stabilizer, a light absorber, a metal deactivator, and a pigment.

Other resins for improving various physical properties,
Rubbers and fillers may be blended. Antioxidants include phenol-based, phosphoric-acid-based and sulfur-based antioxidants, and any one can be used. Specific examples of phenolic antioxidants include 2,6-di-tert-butyl-4-methylpheno-
, Tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, tetrakis [methylene-
3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, n-octadecyl-3-
(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate, 4,4'-butylidenebis-
(3-methyl-6-t-butylphenol, triethyleneglycol-bis [3-t-butyl-4-hydroxy-5-methylphenyl) propionate], 3,9-bis [2- [ 3 (3-tert-butyl-4-hydroxy-5-
Methylphenyl) propionyloxy] -1,1-cimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane.

Specific examples of the phosphoric acid-based antioxidant include trisnonylphenyl phosphite, distearylpentaerythritol diphosphite, tris (2,4-di-
t-butylphenyl) phosphite, tetrakis (2,
4-di-t-butylphenyl) -4,4'-biphenylene-di-phosphonite, bis (2,4-di-t-butylphenylpentaerythritol diphosphite, bis (2,6-di-t -Butyl-4-methylphenylpentaerythritol-diphosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite and the like.

Specific examples of the sulfur-based antioxidant include dilauryl-3,3'-thiodipropionate, similistil-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, Pentaerythritol tetrakis (3-laurylthiopropione-
And the like. Next, examples of the light stabilizer include a hindered amine light stabilizer and a phenylbenzoate light stabilizer.

Specific examples of these light stabilizers include bis (2,2,6,6-tetramethyl-4-piperidyl) separate, succinic acid and N- (2-hydroxypropyl)
Condensate with 2,2,6,6-tetramethyl-4-hydroxypiperidine, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracaroxy Silate, N, N'-bis (2,2,6,
6-tetramethyl-4-piperidyl) polymerization condensate of hexamethylenediamine and 1,2-dibromoethane, bis (2,2,6,6-tetramethylpiperidyl) adipate
To bis (2,2,6,6-tetramethylpiperidyl)
Fumarate, poly [6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-
Silyl] [2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino], 2,4-di-
t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, 4-octylphenyl-3,5
-Di-t-butyl-4-hydroxybenzoate, n-
Hexadecyl-3-, 5-di-t-butyl-4-hydroxybenzoate and the like.

As the light absorber, salicylic acid derivatives,
Benzophenone, benzotriazole, benzoyl
And benzotriazole-based and benzoate-based light absorbers are preferred. Benzotriazole-based light absorbers include 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole and 2- (3,5-di-t-). Butyl-
2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- (3,5-t-butyl-2-hydroxyphenyl) benzotriazole , 2- (2-hydroxy-5-octylphenyl) benzotriazo-
And 2- (2-hydroxy-3,5-di-t-amylphenyl) benzotriazole.

As the metal deactivator, oxalic acid derivatives,
Salicylic acid derivatives, hydrazine derivatives and the like;
(N-saltyloyl) amino-1,2,4-triazo-
, Decamethylenecarboxylic acid saltyloyl hydrazide,
N, N-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, bis (2-phenoxypropionyl hydrazide isophthalate,
N-formyl-N′-salicyloyldazine, 2,2-
Oxamidobis- [ethyl-3- (3,5, -di-t-
Butyl-4-hydroxyphenyl) propionate, oxalyl-bis-benzylidenehydrazide and the like.

As the pigment, chromium oxide, graphite,
Navy blue, potassium ferrocyanide, zinc green, copper chloride phthalocyanine line, phthalocyanine line
Naphthol green, malachite green lake,
Copper phthalocyanine bull, cobalt bull, phthalocyanine bull, fostosky bull, indanthren ble, basic zinc chromate, chromium vermilion red, cadmium red, para red, brilliant cumin, brilliant scarlet Quinacridone red, lysole red, bar million, thioingo red, mingamiya red, fast yellow, hanzaero, olamine lake, benzidine erotic, isoindrian erotic,
Examples include zinc sulfide, titanium oxide, and carbon black.

Further, if necessary, other resins, rubbers, fillers and additives can be added to improve various physical properties. For example, as impact modifiers, ethylene-propylene copolymer rubber, polybutadiene rubber, styrene-butadiene-styrene block copolymer rubber (S
BS), addition of SBS hydrogenated styrene-ethylene-butylene-styrene block copolymer rubber, etc., and taking into account the characteristics of the helmet, metal powder, talc, mica, calcium carbonate, silica, aluminum hydroxide, hydroxide It is also possible to add an inorganic filler such as magnesium, calcium sulfate, short glass fiber, calcium titanate whisker, an organic filler such as a crosslinked resin powder, and a flame retardant or a flame retardant auxiliary.

Further, the thermoplastic resin may contain an antistatic agent. Examples of the antistatic agent include fatty acid salts, higher alcohol sulfates, aliphatic amine or amide sulfates, aliphatic alcohol phosphates, alkyl allyl sulfonates, and basic fatty acid sulfones. Anionic antistatic agents such as salts, quaternary ammonium salts, cationic antistatic agents such as alkylpyridium salts, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene Examples include nonionic antistatic agents such as alkylamines, polyoxyethylene alkylamides and polyoxyethylene sorbitan alkyl esters, and amphoteric antistatic agents such as imidazoline derivatives.

In the production of glass fiber reinforced thermoplastic resin, the composite of glass fiber and thermoplastic resin is usually used.
It is performed in the form of a glass fiber bundle in which a plurality of filaments are bundled, so-called fiber roving or sliver. The fiber bundle is introduced into a die, contacted and impregnated with a molten thermoplastic resin supplied from an extruder, and then pulled out from the die.

At this time, it is also possible to adopt a method in which the fiber bundle is treated with a liquid such as liquid paraffin, the fiber bundles are independently introduced into a die, and a plurality of bundles are collectively collected. After the drawn out strand is cooled, it is taken out by a take-off machine and cut by a cutter to form pellets. At this time, the shape to be pulled out may be any of a columnar shape, a sheet shape, a tape shape, a band shape, and the like.

The length of the glass fiber reinforced thermoplastic resin pellet is 3 to 100 mm, more preferably 5 to 50 mm, as described above. The present invention is to obtain a helmet by expanding and molding the glass fiber reinforced thermoplastic resin produced as described above as a raw material. Any molding method, such as an injection molding method, an injection compression molding method, or an injection press molding method, can be employed as a molding method employed in the expansion molding.

When a material containing glass fiber reinforced thermoplastic resin pellets manufactured as described above is used for injection molding, the mold or core is moved so as to increase the cavity volume immediately after the completion of the molding, thereby obtaining the glass fiber. Inflated using the restoring force (spring back phenomenon) caused by the entanglement of the helmet inside the core (core)
(In the present invention, it may be referred to as a bubble or a bubble).

Further, the core is opened at the time of injection molding, the core is advanced at the same time as the start of injection or once during injection, and after injection and compression, the mold is removed until the cavity volume reaches a predetermined molded product thickness. It can also be moved and expanded by the springback force. Further, in the expansion molding in the injection molding, the core is previously moved to a position corresponding to the amount of the filled resin, an initial cavity-clearance is set, the mold is clamped, and the resin is transferred to the cavity. A method of completely filling, then retracting the core to a predetermined thickness, and expanding the molded product is also employed.

In the expansion molding in the injection compression molding, specifically, a core is previously set at a position where the amount of the filled resin (initial cavity-clearance) and the amount of the compression stroke are added. After the mold is closed and injection-compressed, the molten resin is completely filled in the cavity, a solidified layer is formed on the surface of the molded product, and the core is retracted to a predetermined thickness to expand the molded product. A method can be adopted.

One of the features of the present invention is that a continuous gap layer is formed inside a helmet which is a molded product by expansion molding. By forming the continuous void layer, a helmet that is lightweight and has excellent properties such as impact resistance can be obtained, and this object cannot be achieved with closed cells.

In the expansion molding according to the present invention, nitrogen gas, carbon dioxide gas, argon, or the like may be press-fitted into the molded article after the start or end of the expansion in the mold. The gas pressure at the time of gas injection is usually 0.1 to 200 kg.
/ Cm ² , but in order to avoid the occurrence of a large hollow portion inside the molded product and to prevent the molded product from having poor appearance due to gas leakage, 0.1 to 20 kg / g.
A range of cm ² is preferred.

In the expansion molding, expansion,
In particular, a small amount of blowing agent can be used to promote initial expansion. The foaming agent is not particularly limited as long as it is decomposed by heat to generate gas. For example, oxalic acid derivatives, azo compounds, hydrazine derivatives, semicarbazides, azide compounds, nitroso compounds, triazo-
Urea, nitrite and the like can be used.

Specific examples include azodicarbonamide, benzenesulfohydrazide, N, N-dinitropentamethylenetetramine, terephthalazide and the like. These foaming agents are usually used as a master batch mixed at a high concentration in a thermoplastic resin, and the amount used is as small as 0.01 to 3 parts by weight with respect to 100 parts by weight of the thermoplastic resin. It is.

The foaming agent is not limited to these chemically decomposed foaming agents, but may be any of water, alcohol, propane, and the like, as long as a gas is generated when the thermoplastic resin used is heated and melted.
Physical blowing agents such as butane, fluorine compounds and organic solvents may be used. The present invention is to obtain a helmet by expanding and molding the glass fiber reinforced thermoplastic resin in this way,
The expansion ratio of the molded helmet, from the viewpoint of forming a continuous gap, the helmet, especially the top,
It is desirable to carry out expansion molding so that the ratio becomes 1.2 to 4.0 times, preferably 1.5 to 3.0 times.

If the expansion ratio is less than 1.2 times, it is not possible to achieve a sufficient weight reduction, and if it exceeds 4.0 times, it is not preferable because it becomes close to a hollow helmet. The helmet thus obtained is lightweight and rigid, and has excellent impact resistance and shock absorption.
When attached, there is no phenomenon of "steaming" and the helmet is rich in comfort.

According to the present invention, there is provided a helmet characterized by being formed by expanding a glass fiber reinforced thermoplastic resin.

[0045]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 A glass fiber containing 65% by weight and having a length of 16 mm and a diameter of 2.
A 3 mm glass fiber reinforced polypropylene resin pellet (polypropylene resin MI: 60) was dry-blended with a polypropylene resin (MI: 60) pellet so that the glass fiber content was 40% by weight, and the molding temperature was 2%.
Injection molding was performed at 50 ° C and a mold temperature of 60 ° C. In this injection molding, a gas pin is incorporated.
A helmet mold having a variable thickness from 0 to 8 mm was used. The injection molding machine used had a mold clamping force of 350 ton, and the Idemitsu IPM unit was used for the forward and backward operations of the mold. In the injection molding, the set thickness at the start of the injection was 2 mm, and 3 seconds after the completion of the injection, the core was lowered by 1 mm to make the product thickness 3 mm. When this core back is activated,
Four seconds after the completion of the injection, nitrogen gas was injected at a pressure of 2 MPa. Table 1 shows the evaluation results of the obtained helmet.

Example 2 A glass fiber containing 60% by weight and having a length of 12 mm and a diameter of 2.
A 3 mm glass fiber-reinforced polypropylene resin pellet (polypropylene resin MI: 60) was dry-blended with a polypropylene resin (MI: 60) pellet so that the glass fiber content was 30% by weight. Batch (EE-115 manufactured by Eiwa Chemical Co., Ltd.
Foaming agent 10% by weight)
0.5% by weight was blended and injection molded at a molding temperature of 250 ° C. and a mold temperature of 60 ° C. The injection molding machine used was
This is the same as the first embodiment. In the injection molding, the set thickness at the start of the injection was 2 mm, and two seconds after the completion of the injection,
The core was lowered by 2 mm, and the product thickness was set to 4 mm. At the time of this core back operation, 2 MPa of nitrogen gas 2 seconds after the completion of injection
Pressed in. Table 1 shows the evaluation results of the obtained helmet.

Example 3 A glass fiber containing 65% by weight and having a length of 12 mm and a diameter of 2.
A 3 mm glass fiber-reinforced polypropylene resin pellet (polypropylene resin MI: 60) was dry-blended with a polypropylene resin (MI: 60) pellet so that the glass fiber content was 30% by weight. Batch (EE-11 manufactured by Eiwa Chemical Co., Ltd.)
5, 10% by weight of a foaming agent) and 0.3% by weight of the dry blended, and a molding temperature of 250 ° C.
Injection molding was performed at a mold temperature of 60 ° C.

The injection molding machine used is the same as in the first embodiment. At the time of injection molding, the set thickness at the start of injection was 3 mm, and 2 seconds before the completion of injection, the core was advanced 1 mm to compress the resin, completely fill the cavity with the resin, and 2 seconds after the completion of injection, The core was lowered by 3 mm to make the product thickness 5 mm. At the time of the core back operation, 4 seconds after the completion of the injection, nitrogen gas was injected at a pressure of 2 MPa.

Table 1 shows the evaluation results of the obtained helmet. Comparative Example 12 mm in length and 65 mm in weight containing glass fiber.
A 3 mm glass fiber reinforced polypropylene resin pellet (polypropylene resin MI: 60) was dry-blended with a polypropylene resin (MI: 60) pellet so that the glass fiber content was 40% by weight. Batch (EE-11 manufactured by Eiwa Chemical Co., Ltd.)
5, 10% by weight of a foaming agent) was blended at 1% by weight, and injection-molded at a molding temperature of 250 ° C. and a mold temperature of 60 ° C. with a set thickness of 2 mm.

The injection molding machine used is the same as in the first embodiment. At this time, core back and gas injection were not performed. Table 1 shows the evaluation results of the obtained helmet.

[Table 1]

[0052]

According to the present invention, there is provided a helmet which is lightweight, rigid and excellent in impact resistance and shock absorption, and is useful as a safety hat suitable for use in various working environments. is there.

Claims (4)

[Claims] 1. A helmet obtained by expanding and molding a glass fiber reinforced thermoplastic resin. 2. The helmet according to claim 1, wherein the glass fiber is a long fiber. 3. The helmet according to claim 1, wherein the amount of the glass fibers in the glass fiber reinforced thermoplastic resin is 20 to 80% by weight. 4. The expansion ratio in expansion molding is from 1.2 to 1.2.
The helmet according to claim 1, wherein the helmet is 4.0 times.