JPH0891370A - Pallet made of synthetic resin - Google Patents

Abstract

PURPOSE: To provide a pallet made of synthetic resin which contains small amounts of filler and is lightweight and has improved external appearance and impact resistance, and moreover has improved high-temperature creep characteristics and high rigitity. CONSTITUTION: A pallet made of synthetic resin is formed by molding a mixture comprised of (A) thermoplastic resin, (B) filler in the form of inorganic powder, (C) fiber composite pellets, in which fibers are substantially parallelly composited and length of the fibers is 3-30mm, and which are comprised of (a) continuous fibers, and (b) thermoplastic resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin pallet. More specifically, it has a low filler content compared to conventional pallets, so it is low in density and lightweight, has good moldability, has a good appearance, and is impact resistant. TECHNICAL FIELD The present invention relates to a synthetic resin pallet having excellent properties, high temperature creep characteristics and good rigidity.

[0002]

2. Description of the Related Art In recent years, pallets capable of handling a large amount of products all at once have been widely used in the transportation and storage of products. This pallet has a synthetic resin pallet and a wooden pallet, but the synthetic resin pallet has properties such as no wood chips, no water immersion, and less corrosion than the wooden pallet. It has excellent hygiene and durability and has been widely used in general. However, since resins such as polypropylene and polyethylene alone have poor creep performance at high temperatures, they cannot be used at high temperatures and under high loads, so inorganic fillers such as talc are added to improve rigidity and heat-resistant creep properties. A synthetic resin pallet formed by molding the composite resin is used. However, performance improvement is required by further improvement of creep characteristics.

By the way, a fine powder filler (for example, talc or the like) having a spherical shape, a plate shape, or a rod shape or a short fiber filler (for example, glass fiber or whiskers) is blended with a resin such as polypropylene, polyethylene or polystyrene. As a result, the rigidity (flexural modulus), especially the rigidity at high temperature, is improved according to the blending ratio, but the creep characteristics at high temperature are not easily improved despite the increased rigidity. If the amount of filler is increased in order to improve the creep property at high temperature, the resulting pallet will increase in weight due to the increase in specific gravity, will cause poor molding due to deterioration of fluidity during melting, and deterioration of impact resistance. Problems such as product drop cracks occur.

[0004]

Under the circumstances, the present invention has a smaller filler content than the conventional one,
An object of the present invention is to provide a synthetic resin pallet which has low density and light weight, good moldability, good appearance, excellent impact resistance, good high temperature creep characteristics and good rigidity.

[0005]

As a result of earnest studies to develop a synthetic resin pallet having the above-mentioned preferable properties, the present inventor has found that a thermoplastic resin, an inorganic powder filler and a fiber length are specified. It has been found that a pallet formed by molding a mixture of lengths of fiber composite pellets can serve its purpose. The present invention has been completed based on such findings. That is, the present invention relates to (A) a thermoplastic resin,
A mixture comprising (B) an inorganic powder filler and (C) (A) continuous fibers and (B) a thermoplastic resin in which the fibers are composited substantially in parallel, and a fiber composite pellet having a fiber length of 3 to 30 mm. Provided is a molded synthetic resin pallet.

In a preferred embodiment for carrying out the present invention, the mixture contains 40 to 95% by weight of resin component, 1 to 40% by weight of inorganic powder filler and 1 to 40% by weight of fiber.
The synthetic resin pallet, which is composed of The synthetic resin pallet of the present invention is obtained by molding a mixture of (A) a thermoplastic resin, (B) an inorganic powder filler, and (C) a fiber composite pellet. The thermoplastic resin used as the component (A) is not particularly limited, and examples thereof include polyolefin resin, polyvinyl chloride resin, polyamide resin, polyester resin, polyacetal resin, polycarbonate resin, polyaromatic ether or thioether. Examples thereof include resins, polyaromatic ester resins, polysulfone resins, styrene resins, acrylate resins and the like.

Examples of the polyolefin resin include homopolymers of α-olefins such as ethylene; propylene; butene-1; 3-methylbutene-1; 3-methylpentene-1; 4-methylpentene-1 and the like. And copolymers of these with other copolymerizable unsaturated monomers. Typical examples are high density, medium density, low density polyethylene, linear polyethylene, ultra high molecular weight polyethylene, polyethylene resin such as ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, syndiotactic. Tic polypropylene, isotactic polypropylene and propylene-
Examples thereof include polypropylene-based resins such as ethylene block copolymers and random copolymers, and poly-4-methylpentene-1.

As the polyvinyl chloride resin, for example,
Examples thereof include vinyl chloride homopolymers and copolymers with unsaturated monomers copolymerizable with vinyl chloride. Examples of the copolymer include vinyl chloride-acrylic acid ester copolymer, vinyl chloride-methacrylic acid ester copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-vinyl acetate copolymer. Examples thereof include polymers and vinyl chloride-vinylidene chloride copolymers. further,
Those obtained by post-chlorinating these polyvinyl chloride resins to increase the chlorine content can be used.

As the polyamide resin, for example, 6-
A ring-opening polymerization of a cycloaliphatic lactam such as nylon or 12-nylon, 6,6-nylon; 6,10-nylon; 6,12-nylon, etc., by condensation polymerization of an aliphatic diamine and an aliphatic dicarboxylic acid. Polycondensation product of aromatic diamine and aliphatic dicarboxylic acid such as polycondensation product of m-xylenediamine and adipic acid, polycondensation product of p-phenylenediamine and terephthalic acid, and m-phenylenediamine Examples thereof include condensation polymerization products of aromatic diamines and aromatic dicarboxylic acids such as condensation polymerization products of and isophthalic acid, and condensation polymerization products of amino acids such as 11-nylon.

Examples of the polyester resin include those obtained by condensation polymerization of aromatic dicarboxylic acid and alkylene glycol, and specific examples thereof include polyethylene terephthalate and polybutylene terephthalate. Examples of the polyacetal resin include homopolymers of polyoxymethylene and formaldehyde-ethylene oxide copolymer obtained from trioxane and ethylene oxide.

The polycarbonate resin is 4,
A 4'-dihydroxydiarylalkane-based polycarbonate, particularly a bisphenol A-based polycarbonate obtained by a phosgene method of reacting bisphenol A with phosgene or a transesterification method of reacting bisphenol A with a carbonic acid diester such as diphenyl carbonate is preferably used. . In addition, modification in which a part of bisphenol A is replaced with 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane or 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane Bisphenol A-based polycarbonate and flame-retardant bisphenol A-based polycarbonate can also be used.

The polyaromatic ether or thioether resin has an ether bond or a thioether bond in its molecular chain. Examples of such a resin include polyphenylene ether, polyphenylene ether grafted with styrene, and polyether. Examples include ether ketone and polyphenylene sulfide. Examples of the polyaromatic ester resin include polyoxybenzoyl obtained by polycondensation of p-hydroxybenzoic acid, polyarylate obtained by polycondensation of bisphenol A and aromatic dicarboxylic acid such as terephthalic acid and isophthalic acid. Is mentioned.

The polysulfone-based resin has a sulfone group in the molecular chain, and examples thereof include polysulfone and phenylene group obtained by condensation polymerization of bisphenol A and 4,4'-dichlorodiphenylsulfone. Include a polyether sulfone having a structure in which p is linked to the p-position via an ether group and a sulfone group, and a polyaryl sulfone having a structure in which a diphenylene group and a diphenylene ether group are alternately linked via a sulfone group. it can.

Examples of the styrene resin include homopolymers of styrene and α-methylstyrene, copolymers of these, and copolymers of unsaturated monomers copolymerizable therewith. As typical examples, general-purpose polystyrene, impact-resistant polystyrene, heat-resistant polystyrene (α-methylstyrene polymer), syndiotactic polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene copolymer ( AS), acrylonitrile-chlorinated polyethylene-styrene copolymer (ACS), acrylonitrile-ethylene propylene rubber-styrene copolymer (AES),
Examples thereof include acrylic rubber-acrylonitrile-styrene copolymer (AAS).

Examples of acrylate resins include methacrylic acid ester polymers and acrylic acid ester polymers, and examples of these monomers include methacrylic acid and acrylic acid methyl, ethyl, n-propyl, isopropyl. , Butyl ester, etc. are used, and a typical example of industrial molding material is methyl methacrylate resin.

Among these thermoplastic resins, a polyolefin resin is preferable, and a polypropylene resin is particularly preferable. Further, in the present invention, this thermoplastic resin may be used alone or in combination of two or more kinds. In addition, in the mixture, the inorganic powder filler used as the component (B) is not particularly limited,
Any shape such as a spherical shape, a plate shape, or a rod shape can be used. Examples of such inorganic powder fillers include oxides such as silica, diatomaceous earth, barium ferrite, beryllium oxide and pumice, hydroxides such as aluminum hydroxide, magnesium hydroxide and basic magnesium carbonate, and calcium carbonate. , Magnesium carbonate, dolomite,
Carbonates such as dawsonite, sulfates or sulfites such as calcium sulfate, barium sulfate, ammonium sulfate, calcium sulfite, talc, clay, mica, asbestos, silicates such as calcium silicate, montmorillonite, bentonite, carbon black, graphite, etc. Carbons, molybdenum sulfide, zinc borate, barium metaborate, calcium borate, sodium borate and the like.

These inorganic powder fillers have an average particle diameter of 0.5 to 0.5 in order to obtain a pallet having desired physical properties.
Those in the range of 1,000 μm, preferably 1 to 500 μm are suitable. Further, the inorganic powder filler may be used alone or in combination of two or more kinds. Among these inorganic powder fillers, talc and mica are preferable from the viewpoint of the rigidity of the pallet. Furthermore, in the mixture, as the component (C), the continuous fiber (D) and the continuous fiber (D) are used.
A fiber composite pellet in which fibers are composited in parallel with a thermoplastic resin is used. There is no particular limitation on the continuous fiber of the component (a) in this fiber composite pellet,
For example, glass fiber, carbon fiber, boron fiber, silicon carbide fiber, or metal fiber such as aluminum fiber, stainless fiber, copper fiber, brass fiber, nickel fiber, polyamide fiber, polyester fiber, polyarylate fiber, polyimide fiber, or other organic fiber. Etc. can be used.
These fibers may be used alone or in combination of two or more, and glass fiber is particularly preferable. The diameter of the fibers is 3 to 50 μm, preferably 6 to 30 μm from the viewpoints of handleability and mechanical properties of the resulting pallet.
It is preferably in the range of m.

In the present invention, the above fibers may be previously treated with a surface treatment agent in order to improve the wettability and the adhesiveness with the resin. Examples of the surface treatment agent include silane-based, titanate-based, aluminum-based, chromium-based, zirconium-based, borane-based coupling agents and the like. Among these, silane-based coupling agents and titanate-based coupling agents are listed. Is preferable, and a silane coupling agent is particularly preferable.

Examples of the silane coupling agent include triethoxysilane, vinyltris (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-
Examples thereof include mercaptopropyltrimethoxysilane and γ-chloropropyltrimethoxysilane. Among these, γ-aminopropyltriethoxysilane, N-β
Aminosilanes such as-(aminoethyl) -γ-aminopropyltrimethoxysilane are preferred.

The method of treating the fibers with the surface treating agent is not particularly limited, and any conventionally used method such as an aqueous solution method, an organic solvent method, or a spray method can be used.
Any method can be used. In this way, it is desirable to use the fiber bundle pretreated with the surface-treating agent by using an appropriate sizing agent, preferably 100 to 10,000 fibers, more preferably 300 to 5,000 fibers. . Examples of the sizing agent include urethane-based,
There are acrylic type, butadiene type, epoxy type and the like, and any of them can be used, but among these, urethane type is preferable. The urethane sizing agent usually contains polyisocyanate obtained by polyaddition reaction of a diisocyanate compound and a polyhydric alcohol in a proportion of 50% by weight or more, and is oil-modified, moisture-curable, block-type, etc. There is a one-pack type and a two-pack type such as a catalyst hardening type and a polyol hardening type, and both can be used.

In the present invention, a fiber composite pellet is prepared using the above-mentioned continuous fiber as the component (a) and the thermoplastic resin as the component (b), but the preparation method is not particularly limited, and it is conventionally known. Any method can be used. For example, a fiber bundle obtained by bundling the continuous fibers is supplied into a die, brought into contact with a molten thermoplastic resin, the thermoplastic resin is impregnated in the fiber bundle, and then the fiber bundle is drawn out from the die and cooled. Fiber composite pellets are produced by cutting into lengths. At this time, as the thermoplastic resin used as the component (b), the same ones as those exemplified as the component (A) can be mentioned. The thermoplastic resin as the component (b) may be the same as or different from the component (A), but is preferably the same.

In order to improve the wettability and adhesiveness between the fiber and the thermoplastic resin, for example, when a polyolefin resin is used as the thermoplastic resin of the component (1) (b), unsaturated carboxylic acids are used. It is preferable to add a modified polyolefin resin.

Examples of the polyolefin resin used for the modified polyolefin resin used here include polypropylene, polyethylene, ethylene-α-olefin copolymer rubber, ethylene-α-olefin-non-conjugated diene compound copolymer ( Examples thereof include EPDM), ethylene-aromatic monovinyl compound-conjugated diene compound copolymer rubber, and the like. Examples of the α-olefin include propylene; butene-1; pentene-
1; hexene-1; 4-methylpentene-1 and the like. These may be used alone or in combination of two or more. Among these polyolefin resins, polypropylene and polyethylene are preferable, and polypropylene is most preferable.

The unsaturated carboxylic acids used for modification include unsaturated carboxylic acids and their derivatives. Examples of the unsaturated carboxylic acids include acrylic acid,
Methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, sorbic acid, mesaconic acid, angelic acid, and the like, and derivatives thereof,
There are acid anhydrides, esters, amides, imides, metal salts, etc., for example, maleic anhydride, itaconic anhydride, citraconic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, monoethyl maleate. , Acrylamide, maleic acid monoamide, maleimide, N-butyl maleimide, sodium acrylate, sodium methacrylate and the like. Of these, unsaturated dicarboxylic acids and their derivatives are preferable, and maleic anhydride is particularly preferable.

These unsaturated carboxylic acids and derivatives thereof may be used alone or in combination of two or more when modifying the polyolefin resin. The modification method is not particularly limited, and various conventionally known methods can be used. For example, a method in which the polyolefin resin is dissolved in a suitable organic solvent and unsaturated carboxylic acid or its derivative and a radical generator are added and stirred and heated, or graft copolymerization is performed by supplying each of the above components to an extruder. The method of carrying out can be used. The modified polyolefin resin is preferably one in which the amount of the unsaturated carboxylic acid or its derivative added is in the range of 0.01 to 20% by weight, preferably 0.1 to 10% by weight, and particularly maleic acid-added polypropylene. Is preferred. The intrinsic viscosity [η] (135 ° C. in decalin) of the polyolefin resin modified with unsaturated carboxylic acids is 0.05 to 5.
It is 0 deciliter / g, preferably 0.1 to 3.0 deciliter / g.

The composite pellets are produced, for example, by introducing the continuous fiber into a die and heating it at a temperature of 20 supplied from an extruder.
It is coated with a molten polyolefin resin at about 0 to 300 ° C. and is drawn out from a nozzle having a thin tip. At this time, since the tip portion of the nozzle is made thin, pressure is applied and the impregnation of the fiber bundle with the polyolefin resin is promoted. The strand drawn out from the nozzle is cooled, taken up by a take-up machine, and then cut by a cutter to produce a fiber composite pellet. The polyolefin resin used for this impregnation preferably has a relatively low molecular weight. For example, in the case of polypropylene resin, the melt index (MI) [230 ° C., 2.16 kgf] is 200 g / 10 minutes or more. Can be shown.

In the present invention, the fiber composite pellet must have a fiber length of 3 to 30 mm. If the fiber length deviates from the above range, the creep characteristics and mechanical properties at high temperature of the pallet obtained will be insufficient. From the viewpoint of the creep characteristics and mechanical properties of the pallet at high temperature, the preferable fiber length is in the range of 4 to 25 mm, particularly 5 to 20 mm.

In the fiber composite pellets thus obtained, the content ratio of the fiber and the resin component is 30 to 30
At 80% by weight, the resin component is preferably in the range of 70 to 20% by weight. If the fiber content is less than 30% by weight, the fiber amount is insufficient and it is difficult to quantitatively draw it.
If it exceeds 0% by weight, it becomes difficult to impregnate the resin. From the viewpoint of resin impregnability and drawability, it is particularly preferable that the fiber content is in the range of 40 to 70% by weight and the resin component content is in the range of 60 to 30% by weight.

In the present invention, the thermoplastic resin as the component (A) and the inorganic powder filler as the component (B) are kneaded with, for example, a Banbury mixer, a single-screw or twin-screw extruder, a kneader, etc. The mixture can be prepared by dry blending the fiber-reinforced pellets of the component (C) with a tumbler, a cone blender, a ribbon blender or the like. It is also possible to first prepare a masterbatch of the inorganic powder filler as the component (B), then add the components (A) and (C) and dry blend to prepare a mixture. That is,
It is preferable that at least the component (C) is molded into a pallet by only one stage of melt-kneading, without previously melt-kneading the components (A), (B) and (C) to produce pellets as a composition. . In this mixture, the resin component [(A) component thermoplastic resin and (C)
Total amount of component (b) with the thermoplastic resin] is 40 to 95% by weight, preferably 45 to 90% by weight, more preferably 5
0-80% by weight, 1-40% by weight of inorganic powder filler,
Preferably 5 to 38% by weight, more preferably 10 to 35
% By weight, and 1-40% by weight of fiber, preferably 2-3
It is desirable to contain 5% by weight, more preferably 3 to 30% by weight. If the content of the inorganic powder filler is less than 1% by weight, the rigidity and creep properties at high temperature are insufficient, and if it exceeds 40% by weight, the weight increases and the fluidity at the time of melting is poor, resulting in poor molding. And the appearance of the pallet is deteriorated, and the impact resistance is lowered.
If the fiber content is less than 1% by weight, the creep characteristics and mechanical properties at high temperature are insufficient, and if it exceeds 40% by weight, the appearance of the pallet is deteriorated. If desired, known additives such as antioxidants, heat stabilizers, ultraviolet absorbers, light stabilizers, lubricants, flame retardants, mold release agents, antistatic agents, and colorants are added to the composition. can do.

In the present invention, the mixture thus obtained is manufactured into a pallet by a known molding method such as injection molding. When the above composition is molded, it usually becomes a non-foamed molded product, but it may be slightly foamed depending on the application of the pallet. In this case, resin component 1
If about 0.1 to 1.2 parts by weight of the foaming agent is mixed with 00 parts by weight, the expansion ratio is about 1.05 to 4 times, preferably 1.2 to
A molded product that is about twice as large can be obtained. As the foaming agent, for example, diisopropylhydrazodicarboxylate, 5-phenyltetrazole, trihydrazinotriazine, barium azodicarboxylate, hydrazodicarbonamide and the like can be used. The shape and structure of the pallet is
It is appropriately selected depending on the application and the required strength, for example, a structure in which upper and lower deck boards and leg members connecting the deck boards are integrally formed by injection molding, or by dividing the deck board and leg members, etc. What is formed, and these are assembled using means such as fitting, adhesion with an adhesive, and fusion with high frequency or ultrasonic waves are optional.

[0031]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The physical properties of the pallet were measured as follows. (1) Creep property Elongation (m
m) was measured to determine the creep characteristics. (2) Bending compressibility Measured under the conditions of JIS K0602, the amount of deformation in the longitudinal direction
(mm) and the deflection rate (%) were determined. (3) Impact resistance A pallet was dropped from a height of 1.2 m and there was no damage or deformation, and it was judged as pass (○).

Production Example 1 (Production of Fiber Composite Pellets) A fiber bundle obtained by collecting 1700 glass fibers having a fiber diameter of 13 μm, which had been surface-treated with an aminosilane coupling agent, was spread with a spreader at 150 ° C. The volatile components in the fiber bundle are removed by a drying oven heated to 250 ° C. and a die heating unit heated to 250 ° C., and 5 fiber bundles are introduced into the die to add 10% by weight of maleic acid-added polypropylene at a temperature of 250 ° C. Polypropylene resin containing [melt index (MI): 250 g / 10
Minute (230 ° C., 2.16 kgf)]. Further, this was pulled out from the nozzle while the pressure was applied by a nozzle having a narrowed tip to promote impregnation, the obtained strand was cooled, and then cut, and the glass fibers were composited substantially in parallel. Fiber composite pellets having a fiber length of 8 mm were produced. The fiber composite pellet was composed of 40% by weight of polypropylene resin and 60% by weight of glass fiber.

Example 1 30% by weight of polypropylene having MI = 6 g / 10 minutes [230 ° C., 2.16 kgf] and talc 70 having an average particle size of 3 μm
A talc masterbatch (M / B) was manufactured by kneading with a Banbury mixer using the weight%. The obtained talc M / B and polypropylene resin (Idemitsu Petrochemical J-6
50H, MI = 6 g / 10 minutes) and the fiber-reinforced pellets obtained in Production Example 1 were dry-blended to the ratio shown in Table 1, followed by molding temperature of 240 ° C. and mold temperature of 40.
Injection molding at ℃ condition, 1.100 × 1.400 × 145m
A m-sized pallet was produced. The weight and physical properties of this pallet are shown in Table 1.

Example 2 In Example 1, the ratio of talc and glass fiber was changed to the first
An experiment was conducted in the same manner as in Example 1 except that the changes were made as shown in the table. The results are shown in Table 1.

Comparative Example 1 An experiment was carried out in the same manner as in Example 1 except that the fiber reinforced pellets were not used and the amount of talc was adjusted to 40% by weight as shown in Table 1. went. The results are shown in Table 1.

Comparative Example 2 Polypropylene resin (made by Idemitsu Petrochemical, J-650H,
(MI = 6 g / 10 min) 65% by weight and 30% by weight of talc were dry-blended, and then fed to the hopper of a twin-screw extruder and kneaded. Further, 5% by weight of chopped strands having a length of 3 mm was supplied to a side feeder of a twin-screw extruder and kneaded to obtain target pellets. The obtained pellets were injection molded under the same conditions as in Example 1 and evaluated.

[0037]

[Table 1]

[0038]

Industrial Applicability The synthetic resin pallet of the present invention has a low filler content as compared with the conventional one, so that it is low in density and lightweight, has good moldability, has a good appearance and is excellent in impact resistance. Good high temperature creep properties and rigidity.

Claims (5)

[Claims] 1. A fiber length obtained by compounding fibers of (A) a thermoplastic resin, (B) an inorganic powder filler and (C) (A) continuous fibers and (B) a thermoplastic resin substantially in parallel. 3 to 30
Synthetic resin pallet formed by molding a mixture of mm fiber composite pellets. 2. The mixture comprises 40 to 95% by weight of a resin component,
The synthetic resin pallet according to claim 1, which comprises 1 to 40% by weight of an inorganic powder filler and 1 to 40% by weight of fibers. 3. The inorganic powder filler has an average particle diameter of 0.5 to 0.5.
The synthetic resin pallet according to claim 1, which has a thickness of 1,000 μm. 4. The synthetic resin pallet according to claim 1, wherein the continuous fibers are glass fibers having a fiber diameter of 3 to 50 μm. 5. The synthetic resin pallet according to claim 1, wherein the fiber composite pellet of the component (C) comprises 30 to 80% by weight of fibers and 70 to 20% by weight of a resin component.