KR960006151B1 - Sheet pallette - Google Patents

Abstract

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Description

Sheet palette

The present invention relates to sheet pallets, in particular cold resistant or high rigid sheet pallets.

More specifically, it is a sheet made of a three-component composition of a polyethylene-based resin such as a propylene polymer, a high density polyethylene, and a rubber-like material, a soft rubber such as an ultra low density polyethylene, or a resin, and has excellent mechanical strength such as cold resistance and rigidity. A sheet pallet having good workability in which a frictional coefficient of a surface on which a sheet of cargo is loaded is larger than a frictional coefficient of a rear surface thereof.

In recent years, in the field of cargo distribution, the system which uses a light and comfortable sheet pallet instead of the conventional wooden pallet and the plastic pallet is spread | distributed rapidly in recent years by the material saving.

Sheet Pallet (a) It saves space for storage, (b) it is inexpensive, (c) it can be omitted in some cases, (d) it is easy to manufacture, and (e) it improves work efficiency. It has many advantages.

This sheet palette is produced using plastic as the main raw material, and various ones having been characterized by their structure, shape, and composition have been proposed.

For example, "Freight Carrier" described in Japanese Patent Application Laid-Open No. 55-16821 has a rough surface formed on at least an upper surface of a sheet pallet having a polyolefin resin thickness of 0.5 to 3.2 mm when carrying or transporting packaged goods. In addition, the upper surface is formed by a rougher surface than the lower surface, so that the static friction coefficient between the upper surface and the cargo is higher than the sliding friction coefficient between the lower surface and the platen, thereby smoothing the unloading operation.

In addition, the "slip palette" described in Japanese Unexamined Patent Application Publication No. 58-1023 has a polyolefin resin as its main component, and is provided with a ruled line on a foam sheet having an apparent specific gravity of 0.4 to 0.7, and a tab is provided at one or more edges thereof. The sheet palette which is characterized by the above-mentioned, and aims at improvement of a breakage prevention of a ruled part, impact resistance, etc. is proposed.

By these methods, basic properties such as water resistance, oil resistance, chemical resistance, strength, heat resistance, impact resistance, etc. of the sheet palette have been obtained more satisfactorily. However, it cannot be said that cold resistance is still sufficient.

Further, as a material for improving cold resistance, impact resistance and the like, a propylene block copolymer or a blend composition of polypropylene and ethylene / propylene copolymer rubber has been developed.

For example, the applicant's "cold resistant sheet palette" described in Japanese Patent Laid-Open No. 62-174233 proposes to improve the cold resistance by using a composition of a propylene polymer and a specific ethylene / α-olefin copolymer. have.

In addition, a composition containing ethylene / propylene copolymer rubber or / and polyethylene for the purpose of improving the impact resistance of polypropylene, etc. (for example, JP-A-39-18746, JP-A-41-7345, JP-A) 55-104334, etc. are also known.

However, in recent years, the cargo distribution has become more complicated, and as the range of use is expanded, both high temperature and low temperature characteristics are required. Especially, considering the use under ultra low temperatures such as cold districts and freezers, it is extremely important to improve the strength, heat resistance, and impact resistance at the same time. Is being done.

In general, since physical properties such as strength, rigidity, and heat resistance in plastic materials are opposite to those of low temperature shock resistance, development of sheet palettes considering the balance between these properties is strongly expected.

It is an object of the present invention to provide a sheet palette which is excellent in workability and excellent in terms of balance between rigidity and low temperature shock resistance, in which the embrittlement temperature is improved by examining the material composition in view of the above point.

Another object is to obtain a good water-soluble inorganic filler and a relatively large amount of the inorganic fillers by appropriately selecting a rubbery material or an ultra low density polyethylene in the composition, thereby making a (dispersion) composition having good interdispersibility between polypropylene and polyethylene. It is to provide a sheet palette excellent in mechanical strength and heat resistance such as rigidity, since impact resistance does not decrease even when the filler is filled.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining according to the said objective, the sheet | seat which was remarkably excellent in cold resistance or rigidity was mixed by mixing a propylene polymer, ethylene (co) polymers, such as a high density polyethylene, a rubbery substance, and an ultra low density polyethylene in a specific ratio. It was found that a pallet was obtained and came to complete the present invention.

That is, the present invention is (A) 55 to 90% by weight of the propylene polymer, (B) ethylene or ethylene of ethylene and α-olefin of 0.91 to 0.97 g / cm³ of work, ethylene-vinyl ester copolymer, ethylenically unsaturated carboxylic acid or Polyolefin resin composition containing 5-30 weight% of at least 1 sort (s) of ethylene (co) polymer chosen from the copolymer with its derivative, (C) rubbery substance, and 5-30 weight% of at least 1 sort (s) of ultra low density polyethylene ( However, the A + B + C is 100% by weight, and the friction coefficient of the surface on which the cargo is loaded is larger than the friction coefficient of the back surface and is 0.3 to 10 mm thick.

As a propylene polymer of (A) component of this invention, a propylene single polymer, a copolymer with another alpha-olefin which has propylene as a main component, a mixture thereof, etc. are mentioned.

More specifically, isotactic polypropylene, syndiotactic polypropylene, propylene-ethylene block copolymers, propylene-ethylene random copolymers, propylene-1-butene copolymers and the like may be used.

The propylene content of the copolymer is preferably at least 60% by weight.

In addition, the melt flow of the propylene-based polymer (hereinafter referred to as MFR) is preferably in the range of 0.1 to 10 g / 10 minutes, preferably 0.5 to 5 g / 10 minutes, for maintaining rigidity, heat resistance, and the like.

If the MFR is less than 0.lg / 10 min, the meltability of the melt becomes poor, a good sheet is difficult to be obtained, and there is a fear that the productivity is lowered.

In addition, when MFR induces 10 g / 10 minutes, there is a concern that physical properties other than the strength of the sheet may decrease.

At least one selected from ethylene having a density of 0.91 to 0.97 g / cm 3 of the component (B) of the present invention and a polymer of ethylene and an α-olefin, an ethylene-vinyl ester copolymer, an ethylenically unsaturated carboxylic acid or a derivative thereof Ethylene (co) polymers are ethylene homopolymers by (Bl) Ziegler-based catalysts or high-pressure radical polymers, or ethylene and α-olefin copolymers, for example, ethylene homopolymers having a density of 0.94 / cm³ or higher, or ethylene and α-olefins. Examples of the copolymer include copolymers of medium / high density polyethylene or α-olefins such as propylene and propylene, butene-1,4-methyl / pentene-1 and hexane-1.

Examples of (B2) low density polyethylene having a density of 0.94 / cm 3 or less include linear low density polyethylene (LLDPE), high pressure method low density polyethylene (HpLDPE), or a mixture thereof. (B3) Ethylene-vinyl ester copolymers include vinyl ester monomers such as vinyl propionate, vinyl acetate, vinyl caproate, vinyl capdylate, vinyl lauryl acid, vinyl stearyl acid and vinyl trifluoroacetate having ethylene as a main component; Of copolymers. Among these, vinyl acetate is particularly preferable.

(B4) is a copolymer with ethylenically unsaturated carboxylic acid or derivatives thereof; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride and itaconic anhydride containing ethylene as a main component; Methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl acrylate, n-butyl methacrylate, cycloacrylate Hexyl, cyclohexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid diethyl ester, fumaric acid monomethyl ester Copolymers with unsaturated carboxylic acid alkyl ester monomers, and ethyl acetate is particularly preferred.

Specific examples of the ethylene copolymer include ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene / acrylic acid / ethyl acrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / vinyl acetate copolymer, ethylene / vinyl acetate / acrylic acid Random copolymers, such as an ethyl copolymer, are mentioned.

The melt flow of the ethylene (co) polymer is preferably in the range of 0.05 to 50 g / 10 minutes, preferably 0.1 to 10 g / 10 minutes, in terms of improving compatibility with the electric polypropylene polymer.

Examples of the (C1) rubbery material of the component (C) of the present invention include ethylene-propylene random copolymer rubber, ethylene-propylene-diene random copolymer rubber, natural rubber, isobutene rubber, butadiene rubber, 1,2-polybutadiene, Styrene-butadiene random copolymer rubber, chloroprene rubber, nitrile rubber, styrene-butadiene-styrene block copolymer rubber, styrene-isoprene-styrene block copolymer rubber, etc., These may be individual or a mixture may be sufficient as them.

Among these, ethylene / propylene / diene random copolymer rubber and ethylene / propylene random copolymer rubber are particularly preferable.

These two rubbers are superior in thermoplasticity to other rubbery materials, are easy to disperse by melt mixing, and do not have a unique scent compared to SBR, isoprene rubber, nitrile rubber or butadiene rubber, or pellets. Since it can be obtained, it is easy to improve and handle when mix | blending, and the thing which has operational advantages, such as the point of freedom of selection also with respect to the form of a composition manufacturing apparatus, is mentioned.

As the diene component of the ethylene-propylene-diene random copolymer rubber, ethylidene norbornene, dicyclopentadiene, 1,4-cyclohexadiene and the like can be used.

In addition, the Mooney viscosity (ML _1-4,100 ° C) of these rubbery materials is preferably in the range of 10 to 100, preferably (ML _1-4,100 ° C) 20 to 90. (ML _{1 -4,100} DEG C) When 10 or less is used, the effect of improving impact resistance is not obtained at all, and when it is 100 or more (ML _1-4 , 100 DEG C), dispersion in matrix resin is bad.

(C2) Ultra low density polyethylene (ULDPE) refers to a polyethylene having a density of less than 0.86 to 0.910 g / cm 3 and exhibiting intermediate properties between linear low density polyethylene and ethylene / α-olefin copolymer rubber.

Specific ethylene / α having properties of, for example, a density of 0.860 to less than 0 910 g / cm 3, a maximum peak temperature (Tm) of 100 ° C. or higher by differential scanning calorimetry (DSC), and 10% by weight or more of boiling n-hexane insolubles. -Olefin copolymer. Polymerization is carried out using a catalyst composed of a solid catalyst component containing at least titanium and / or vanadium and an organoaluminum compound.

The ULDPE is a resin having both a high crystalline portion represented by a linear low density polyethylene and an amorphous portion represented by an ethylene / α-olefin copolymer rubber, mechanical strength, heat resistance, etc., which are characteristic of the former, and rubbery elasticity and low temperature, which are characteristic of the latter. The impact properties and the like coexist in a well-balanced manner, and when used in the present invention, it is extremely useful because a thermoplastic resin composition having a wide range of excellent performances is obtained as described below.

The melt flow is used in the range of 0.01 to 50 g / 10 minutes, preferably 0.05 to 10 g / 10 minutes.

The blending ratio of the composition of the present invention is 55 to 90% by weight of the polypropylene polymer of component (A), 5 to 30% by weight of ethylene (co) polymer of component (B), rubbery material of component (C) or ultra low density 5-30 weight% of polyethylene (however, the sum total of A + B + C shall be 100 weight%).

When the compounding quantity of (B) component of this composition is less than 5 weight%, improvement of impact resistance, especially low temperature shock resistance is not achieved.

Moreover, when this compounding quantity exceeds 30 weight%, strength, rigidity, and heat resistance become weak.

Similarly with respect to the blending amount of the component (C), if the blending amount is less than 5% by weight, the low temperature impact resistance will not be improved, and if it exceeds 30% by weight, the strength, rigidity and heat resistance will be weak.

As the compounding method of the composition, conventionally known ones such as an open mixing roll, an unopened Banbury mixer, an extruder, a kneader, a twin screw extruder, a tumbler and a Henschel mixer can be used.

Moreover, as a kneading method, you may mix, mixing a dry blend, melt mixing, or these three components.

The present invention mixes such (A), (B) and (C) at a desired ratio, and then sheet-forms the sheet by a conventional method such as extrusion molding (for example, T-die method) or calendar method. Ethylene-vinyl acetate copolymer and synthetic rubber on the surface or surface of loading sheet of embossing, sand blast, corona discharge treatment, flame treatment, plasma treatment, etc. By laminating a non-slip agent such as the above, the coefficient of friction of the surface on which the cargo is loaded is increased to prevent cargo slip and damage to the cargo.

The coefficient of friction depends on the packaging material of the cargo, such as paper or plastic, and also on the shape of the bottom of the cargo, the weight of the cargo, etc. For example, the surface of the ball paper is 0.2 to 0.8, preferably as the top surface static friction coefficient. The range of 0.3-0.7 is suitable.

In addition, the thickness of the sheet pallet of the present invention is suitably selected in the range of 0.3 to 10 mm, preferably 0.5 to 5 mm.

If the thickness of the sheet pallet is less than 0.3 mm, the mechanical strength such as the rigidity of the sheet is weak, and if the thickness is more than 10 mm, the characteristics required in the present invention are satisfied, but the weight becomes large, which hinders the unloading automation and handling. There is concern to bring.

The target value of this cold-resistant sheet pallet property is more than 5,000kgf / cm¹ of flexural strength, and less than -50 degreeC of embrittlement temperature.

In this invention, in order to improve heat resistance and rigidity other than cold resistance, it is preferable to add an inorganic filler to the said composition.

(A) 55 to 90% by weight of a propylene polymer, (B) a polymer of ethylene or an ethylene and an α-olefin having a density of 0.91 to 0.97 g / cm3, an ethylene-vinyl ester copolymer, an ethylenically unsaturated carboxylic acid or a derivative thereof Polyolefin resin composition comprising 5 to 30% by weight of at least one ethylene (co) polymer selected from the copolymer, (C) rubbery material, and 5 to 30% by weight of at least one species of very low density polyethylene (A + The said object can be achieved by making into the sheet | seat palette which consists of 5-100 weight part of (D) inorganic fillers with respect to 100 weight part of (total amount of B + C) 100 weight part.

If the amount of the inorganic filler is less than 5 parts by weight, the rigidity, heat resistance, and the like will not be sufficiently improved.

Moreover, when it exceeds 100 weight part, low temperature shock resistance falls.

As the inorganic filler (D) of the present invention, various conventional fillers such as talc, calcium carbonate, carbon black, mica, glass fiber, carbon fiber, aramid resin, asbestos, and those surface-treated with such fillers can be appropriately blended. have.

If necessary, stabilizers, antioxidants, ultraviolet absorbers, lubricants, foaming agents, antistatic agents, flame retardants, crosslinking agents, plasticizers, dyes, pigments and the like can be suitably blended into the composition of the present invention.

(Example)

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these.

(Used resin)

(A) component; <A> polypropylene block copolymer (referred to as PP), (ethylene about 10% by weight, MFR = 1.5 g / 10 min)

(B) component; (B ₁ ) High-density polyethylene (referred to as HDPE) (density 0.956 g / cm 3, MFR = 1.6 g / 10 min.Trade name: Stone Stone Starprene E 715, Nihon Sekiyu Kagaku Kabushiki Kaisha)

(B ₂ ) linear low-density polyethylene (referred to as LLDPE) (density 0.921 g / cm 3, MFR = 1.0 g / 10 min.Trade name: Stone Stone Rico Rex AF 2380, Nippon Sekiyu Chemical Co., Ltd.)

(B ₃ ) Ethylene-vinyl acetate copolymer (referred to as EVA) (density 0.932 g / cm, MFR = 1.0 g / 10 min.Trade name: Stone Stone V 260, Nippon Sekiyu Kagaku Kabushiki Kaisha)

(B ₄ ) Ethylene-ethyl acrylate copolymer (referred to as EEA) (EA content 10% by weight, MFR = 1.5 g / 10 min) Product Name: Stone Stone Lestonestone A 2100, Nippon Sekiyu Kagaku Kabushiki Kaisha

C) component; Rubbery material

(C1) ethylene-propylene random copolymer rubber (referred to as EPR)

An ethylene-propylene copolymer rubber was obtained using vanadium trichloride / ethylaluminum sesquichloride based catalyst. The resulting copolymer rubber was 19 mole% propylene content, Mooney viscosity _{(ML 1-4, 100 ℃) 73} , density 0.862g / ㎤.

Since no peak was confirmed by DSC, no Tm was present and no C ₆ insoluble content was found.

(C2) ethylene / butene-1 copolymer

Ultra low density of ethylene / butene-1 copolymers by copolymerizing ethylene and butene-1 using a catalyst of triethylaluminum with a solid catalyst component obtained from substantially anhydrous magnesium chloride, 1,2-dichloroethane and titanium tetrachloride Polyethylene (ULDPE (1)) was obtained.

This ultra low density polyethylene (ULDPE (1)) had a 10 mol% butene-1 content, a density of 0.900 g / cm 3, a Tm of 120 ° C., a C ₆ insoluble content of 82 wt% and an MFR of 1.5 g / 10 min.

(C3) ethylene-propylene copolymer

Ultra Low Density Polyethylene (ULDPE (2)) consisting of ethylene and propylene copolymers by copolymerizing ethylene and propylene using a solid catalyst component obtained from substantially anhydrous magnesium chloride, anthracene and titanium tetrachloride and a catalyst of triethylaluminum. Obtained.

The ethylene-propylene copolymer was 12 mol% of propylene content, density 0.900g / cm³, Tm = 119 ℃ , C 6 -insoluble matter content of 82%, MFR = 1.3g / 10 minutes.

(C4) ethylene / butene-1 copolymer

A vanadium trichloride / ethyl aluminum sesqui chloride based catalyst was used to obtain ultra low density polyethylene (ULDPE (3)) of ethylene / butene-1 copolymer.

The obtained copolymer is butene-1 content of 6 mol%, density 0.895g / ㎤, Tm = 81 ℃ , C 6 -insoluble content = 1.5 wt%, MFR = 3.5g was / 10 min.

(Test and measurement method)

(MFR)

In conformity with JIS K6760

(Tensile yield strength) and (tensile fracture extension)

In accordance with JIS K 6760

(Measurement method of maximum peak temperature (Tm) by differential scanning calorimetry (DSC)) + It measured by melting | fusing point of ultra low density polyethylene. About 5 mg of sample was precisely weighed from a 100 μm thick film that was hot press-molded, placed in a DSC device, heated at 170 ° C. and maintained at the same temperature for 15 minutes, and then cooled to 0 ° C. at a temperature reduction rate of 2.5 ° C./min. Next, temperature rises to 170 degreeC by the temperature increase rate of 10 degree-C / min from this state, and the peak temperature of the largest peak among the peaks shown while heating up from 0 degreeC to 170 degreeC is called Tm.

(Measurement method of boiling n-hexane insoluble content)

A sheet having a thickness of 200 μm was formed by using a heat press, and three sheets of 20 mm × 30 mm were cut from the sheet, and these were extracted with boiling n-hexane for 5 hours using a double tube Soxhlet extractor. After collecting n-hexane insoluble matter and vacuum drying (7 hours, 50 ° C.), boiling n-hexane insoluble content is calculated from the following formula.

(Examples 1 to 6 and Comparative Examples 1 to 6)

)를 사용하여 수지 온도 235℃, 냉각 로울 온도 100℃, 인수 속도 2m/분의 쉬트 성형 조건으로 두께 1.8mm×폭 1,600mm의 쉬트를 압출성형시키고, 또한 쉬트의 화물을 싣는면(상면)에 엠보스 가공을 하여 쉬트 팔레트 재료를 제조하였다. 상기의 각종 쉬트 팔레트 재료의 배합 조성 및 특성을 표 1에 나타낸다.Each component of the extruder (120 mm)

Sheet) with a resin temperature of 235 ° C, a cooling roll temperature of 100 ° C, and a printing speed of 2m / min. The sheet pallet material was prepared by embossing. Table 1 shows the blending composition and properties of the various sheet palette materials.

The measuring method of a characteristic value is as follows.

Flexural Strength: JIS K7106

Embrittlement Temperature: JIS K6760

[Evaluation results]

As is clear from Table 1, in the examples of the present invention, the flexural strength is high, the embrittlement temperature is sufficiently low, and the balance between stiffness and low temperature impact resistance is excellent.

On the other hand, in the comparative example, these balances were not enough and both could not be satisfied simultaneously.

As described above, the sheet palette is composed of a polypropylene-based polymer, an ethylene (co) polymer and a rubbery material, and a 3TJD powder composition of ultra low density polyethylene, and thus has good chemical properties such as water resistance, oil resistance, and chemical resistance, and is used repeatedly. In addition to endurance, the balance of strength, stiffness, heat resistance and low temperature impact resistance is much better than the conventional ones, and in particular, since the improvement in embrittlement temperature has been achieved, it can be used for a long time even in an ultra low temperature environment.

TABLE 1

Claims (5)

(A) 55 to 90% by weight of a propylene polymer, (B) a polymer of ethylene or an ethylene and an α-olefin having a density of 0.91 to 0.97 g / cm3, an ethylene-vinyl ester copolymer, an ethylenically unsaturated carboxylic acid or a derivative thereof 5 to 30% by weight of at least one ethylene (co) polymer selected from copolymers, (C) a rubber-like material, and a polyolefin-based resin composition containing at least one or more 5 to 30% by weight of ultra low density polyethylene (a total amount of A + B + C) 100 wt%), the sheet pallet having a coefficient of friction greater than that of the back surface and having a thickness of 0.3 to 10 mm. The polymer according to claim 1, wherein the polymer of ethylene or an ethylene with an α-olefin, a ethylene-vinyl ester copolymer and an ethylenically unsaturated carboxylic acid or a derivative thereof having a density of 0.91 to 0.97 g / cm &lt; 3 &gt; , Ethylene-vinyl acetate copolymer and ethylene- (meth) acrylic acid alkyl ester copolymer. The sheet palette according to claim 1 or 2, wherein the rubbery material is ethylene / α-olefin copolymer rubber or ethylene / α-olefin diene copolymer rubber. The maximum peak temperature according to any one of claims 1 to 3, wherein the ultra low density polyethylene is obtained by polymerizing ethylene with an α-olefin having 3 to 12 carbon atoms, and having a density of 0.86 to less than 0.91 g / cm³, by using a differential scanning calorimetry method. A sheet palette which is an ethylene / α-olefin copolymer having not less than 10 ° C. and no less than 10% by weight of boiling n-hexane insoluble content. (A) 55-90 weight% of propylene polymers, (B) Ethylene or polymer of ethylene and an alpha-olefin, ethylene-vinyl ester of density | density 0.91-0.97 g / cm <3>, 5 to 30% by weight of at least one ethylene (co) polymer selected from copolymers, copolymers with ethylenically unsaturated carboxylic acids or derivatives thereof, and (C) at least one of 5 to 30% by weight of a rubbery material, ultra low density polyethylene The sheet | seat palette which consists of 5-100 weight part of inorganic fillers with respect to the polyolefin resin composition (however, the total amount of A + B + C shall be 100%), and (D) 100 weight part of said polyolefin resin compositions.