JP3493080B2 - Cold-resistant sheet pallet - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet pallet having high resistance to cold, and more particularly to a sheet pallet comprising a propylene polymer, a specific ethylene (co) polymer and optionally an ethylene polymer and having an upper surface. Is larger than that of the lower surface and has a thickness of 0.3 to 10 mm.

[0002]

2. Description of the Related Art With the recent resource saving, in the field of freight distribution, a distribution system using a light sheet pallet instead of a conventional wooden pallet or plastic pallet is rapidly spreading. . The sheet pallet (a) saves space for storage,
(B) It has many advantages such as low cost, (c) in some cases, collection can be omitted, (d) production is simple, and (e) work efficiency can be improved. Various types of sheet pallets (also referred to as slip sheets) have been proposed, which are manufactured by using plastic as a main raw material and are characterized by their structure, shape, and composition.

For example, the "carrying platform" disclosed in Japanese Utility Model Publication No. 55-16821 has a rough surface on at least the upper surface of a sheet pallet of polyolefin thermoplastic resin having a thickness of 0.5 to 3.2 mm. The upper surface is formed to be rougher than the lower surface, so that when the packaged cargo is transported or transferred, the static friction coefficient between the upper surface and the cargo is slid between the lower surface and the platen. The coefficient of friction is set higher than that of the product to facilitate cargo handling work.

The "slip pallet" disclosed in Japanese Examined Patent Publication No. 58-1023 has a polyolefin resin as a main component and a ruled line is formed on a foamed sheet having an apparent specific gravity of 0.4 to 0.7 mm to form a peripheral edge. The sheet pallet is provided with tabs at one or more places and is intended to prevent breakage of the ruled line portion and to improve impact resistance. With these conventional techniques, it has been possible to obtain a sheet pallet that basically satisfies basic properties such as water resistance, oil resistance, chemical resistance, strength, heat resistance, and impact resistance. As a material for improving cold resistance and impact resistance, a propylene / block copolymer or a blend composition of polypropylene and ethylene / propylene rubber has been developed.
The "cold-resistant sheet pallet" disclosed in JP-A-2-174233 discloses a propylene polymer and a specific ethylene / α-
Using a composition consisting of an olefin copolymer,
The purpose is to improve cold resistance. Furthermore, a composition obtained by mixing ethylene / propylene rubber and polyethylene into polypropylene (for example, Japanese Patent Publication No. 39-18746).
Japanese Patent Publication No. 41-7345, Japanese Patent Laid-Open No. 55-10433.
No. 4, etc.) are also known.

However, in recent years, physical distribution has become more complicated, and the characteristics of both high temperature and low temperature have been demanded with the expansion of the range of use. Especially, considering the use at ultra-low temperature in cold regions, freezers, etc.,
Improving low-temperature impact resistance as well as strength and heat resistance is becoming extremely important. Generally, strength, rigidity, heat resistance, etc. of a plastic material are incompatible with impact resistance, especially low temperature impact resistance, so it is difficult to satisfy these at the same time with a conventional composition. It was strongly desired to develop a sheet pallet with consideration.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems, and particularly to provide a cold-resistant sheet pallet excellent in the balance of rigidity and low temperature impact resistance.

[0007]

Means for Solving the Problems The inventors of the present invention have made extensive studies in accordance with the above-mentioned object, and as a result, from a composition comprising a propylene-based polymer, a specific ethylene (co) polymer and optionally an ethylene polymer, It was found that a sheet pallet having excellent cold resistance, rigidity, tensile strength, etc. can be obtained, and the present invention has been accomplished. That is, the present invention is, firstly,
(A) Propylene-based polymer 50 to 95% by weight, (B)
(A) In the presence of a catalyst containing a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton as an essential component, ethylene or ethylene and a carbon number of 3
To (b) density of 0.86 to 0.97 g / cm, which is obtained by (co) polymerizing with .alpha.-olefin of .about.20.
³ , (c) Melt flow rate is 0.01 to 50 g / 1
0 minutes, (d) molecular weight distribution parameter Mw / Mn1.8
To (3.5), and (e) composition distribution parameter C
Composition consisting of 5 to 50% by weight of ethylene (co) polymer having b of 1.2 or less, and 0 to 45% by weight of (C) ethylene polymer (however, (A), (B) and (C)) The total amount of components is 100% by weight), the coefficient of friction of the upper surface is larger than the coefficient of friction of the lower surface, and the thickness is 0.3 to 10 mm. Is.

Secondly, the present invention relates to the above cold-resistant sheet pallet, wherein the (C) ethylene polymer is at least one selected from the following ethylene (co) polymers. is there. [Ethylene-based polymer] (C1) ethylene / α-olefin copolymer having a density of 0.86 to 0.97 g / cm ³ (C2) low-density polyethylene by high-pressure radical polymerization,
Ethylene / vinyl ester copolymer, ethylene and α, β
-Copolymers with unsaturated carboxylic acids or their derivatives

The present invention will be described in detail below. As the propylene-based polymer (A) used in the present invention, a homopolymer of propylene, a copolymer of propylene as a main component with another α-olefin, a mixture thereof, and the like are used. From this viewpoint, crystalline propylene homopolymers, propylene / ethylene block copolymers and the like are preferable.
The α-olefin content in the propylene / α-olefin copolymer is preferably 1 to 20% by weight, respectively. α-
If the olefin content is less than 1% by weight, the impact strength is not sufficient. Also, the content of α-olefin is 20% by weight.
If it exceeds, the rigidity is low and there is a possibility that the sheet is not suitable as a sheet or the like. The melt flow rate (hereinafter referred to as MFR) of the propylene-based polymer is 0.1 to 20 g / 10 mi.
The range of n is preferable, and particularly 0.3 to 10 g / 10 min
Is preferred. If the MFR is less than 0.1 g / 10 min, the fluidity of the molten resin is poor, the screw power of the extruder becomes too high, and it may be difficult to produce a good sheet. On the other hand, when the MFR exceeds 20 g / 10 min, the web of the molten resin hangs down, good molding cannot be performed, and the strength and other physical properties of the sheet may deteriorate.

The ethylene (co) polymer (B) of the present invention is produced by using a transition metal compound of Group IV of the periodic table containing the above-mentioned ligand having a cyclopentadienyl skeleton, and if necessary, a cocatalyst and an organic compound. It can be obtained by copolymerizing ethylene or ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of a catalyst containing an aluminum compound and / or a carrier. Further, the catalyst obtained by preliminarily polymerizing ethylene and / or the α-olefin with the above catalyst may be used as the catalyst.

The above α-olefin has 3 to 10 carbon atoms.
20 and preferably 3 to 12, and specific examples thereof include propylene, butene-1, 4-methylpentene-1, hexene-1, octene-1, decene-1, dodecene-1. The content of these α-olefins is usually 30 mol% or less, preferably 3 to 20 mol%.
It is desirable to be selected within the range.

The above ethylene (co) polymer (B) of the present invention
(A) A cyclopentadienyl skeleton of a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, which is a catalyst for producing a cyclopentadienyl group, a substituted cyclopentadienyl group And an enyl group. The substituted cyclopentadienyl group includes a hydrocarbon group having 1 to 10 carbon atoms, a silyl group, a silyl-substituted alkyl group, a silyl-substituted aryl group, a cyano group, a cyanoalkyl group, a cyanoaryl group, a halogen group, a haloalkyl group, and a halosilyl group. And a substituted cyclopentadienyl group having at least one kind of substituent selected from the group. The substituted cyclopentadienyl group may have two or more substituents, and the substituents may be bonded to each other to form a ring.

Examples of the hydrocarbon group having 1 to 10 carbon atoms include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group and the like. Specific examples thereof include a methyl group, an ethyl group, an n-propyl group and isopropyl. Group, n-butyl group,
Alkyl groups such as isobutyl group, sec-butyl group, t-butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, decyl group; cycloalkyl groups such as cyclopentyl group, cycloalkyl group; phenyl group, tolyl group Examples thereof include aryl groups such as groups; aralkyl groups such as benzyl groups and neophyll groups. Of these, alkyl groups are preferred.

Preferred examples of the substituted cyclopentadienyl group include methylcyclopentadienyl group, ethylcyclopentadienyl group, n-hexylcyclopentadienyl group, 1,3-dimethylcyclopentadienyl group, 1,
3-n-butylmethylcyclopentadienyl group, 1,3
Specific examples thereof include -n-propylmethylethylcyclopentadienyl group. Among these, the substituted cyclopentadienyl group of the present invention is preferably a cyclopentadienyl group substituted with an alkyl group having 3 or more carbon atoms,
A 1,3-substituted cyclopentadienyl group is particularly preferable.

The substituted cyclopentadienyl group in the case where the substituents, ie, the hydrocarbons, are bonded to each other to form one or two or more rings, an indenyl group and a carbon number of 1 are used.
A substituted indenyl group, a naphthyl group, and a carbon number of 1 to 8 substituted with a substituent such as a hydrocarbon group (eg, an alkyl group) having 8 to 8 carbon atoms.
Preferred are a substituted naphthyl group substituted by a substituent such as a hydrocarbon group (alkyl group) and a substituted fluorenyl group substituted by a substituent such as a hydrocarbon group having 1 to 8 carbon atoms (alkyl group). It is mentioned as a thing.

Examples of the transition metal of the group IV transition metal compound containing a ligand having a cyclopentadienyl skeleton include zirconium, titanium and hafnium, with zirconium being particularly preferred.

The transition metal compound usually has 1 to 3 ligands having a cyclopentadienyl skeleton, and when they have 2 or more ligands, they may be bonded to each other by a bridging group. Examples of the cross-linking group include an alkylene group having 1 to 4 carbon atoms, an alkylsilanediyl group, and a silanediyl group.

As a ligand other than the ligand having a cyclopentadienyl skeleton in the transition metal compound of Group IV of the periodic table, hydrogen and C1 to C2 are typical.
And a hydrocarbon group of 0 (alkyl group, alkenyl group, aryl group, alkylaryl group, aralkyl group, polyenyl group, etc.), halogen, metaalkyl group, metaaryl group and the like.

The following are specific examples of the transition metal compound of Group IV of the periodic table containing the above-mentioned ligand having a cyclopentadienyl skeleton. That is, as the monoalkyl metallocene, bis (cyclopentadienyl) titanium methyl chloride, bis (cyclopentadienyl) titanium phenyl chloride, bis (cyclopentadienyl) zirconium methyl chloride, bis (cyclopentadienyl) zirconium phenyl chloride, etc. There is. As dialkyl metallocenes, bis (cyclopentadienyl) titanium dimethyl, bis (cyclopentadienyl) titanium diphenyl, bis (cyclopentadienyl) zirconium dimethyl, bis (cyclopentadienyl) zirconium diphenyl, bis (cyclopentadienyl) ) Hafnium dimethyl, bis (cyclopentadienyl) hafnium diphenyl and the like. As the trialkyl metallocene, cyclopentadienyl titanium trimethyl, cyclopentadienyl zirconium triphenyl, cyclopentadienyl zirconium trineopentyl, cyclopentadienyl zirconium trimethyl, cyclopentadienyl hafnium triphenyl,
Examples include cyclopentadienyl hafnium trineopentyl and cyclopentadienyl hafnium trimethyl.

Further examples include monocyclopentadienyl titanocene such as pentamethylcyclopentadienyl titanium trichloride, pentaethylcyclopentadienyl titanium trichloride, and bis (pentamethylcyclopentadienyl) titanium diphenyl.

The substituted bis (cyclopentadienyl) titanium compounds include bis (indenyl) titanium diphenyl or dichloride, bis (methylcyclopentadienyl) titanium diphenyl or halide; dialkyl, trialkyl, tetraalkyl or pentaalkylcyclopenta. Examples of the dienyl titanium compound include bis (1,2-dimethylcyclopentadienyl) titanium diphenyl or dichloride, bis (1,2)
-Diethylcyclopentadienyl) titanium diphenyl or dichloride or other dihalide complex, dimethylsilyldicyclopentadienyl titanium diphenyl or dichloride as silicon, amine or carbon linked cyclopentadiene complex, methylenedicyclopentadienyl titanium diphenyl or dichloride , And other dihalide complexes.

As the zirconocene compound, pentamethylcyclopentadienyl zirconium trichloride,
Pentaethylcyclopentadienyl zirconium trichloride, bis (pentamethylcyclopentadienyl)
Zirconium diphenyl; as alkyl-substituted cyclopentadiene, bis (ethylcyclopentadienyl) zirconium dimethyl, bis (methylcyclopentadienyl) zirconium dimethyl, bis (n-butylcyclopentadienyl) zirconium dimethyl, haloalkyl or dihalide thereof. Complexes: bis (pentamethylcyclopentadienyl) zirconium dimethyl as dialkyl, trialkyl, tetraalkyl or pentaalkylcyclopentadiene, bis (1,2-dimethylcyclopentadienyl) zirconium dimethyl, and their dihalide complexes, silicon As the carbon-linked cyclopentadiene complex, dimethylsilyldicyclopentadienylzirconium dimethyl or dihalide, methylenedicyclopentene Dienyl zirconium dimethyl or dihalide, such as methylene dicyclopentadienyl zirconium dimethyl or dihalide, and the like.

As another example of the transition metal compound of Group IV of the periodic table of the present invention, a ligand having a cyclopentadienyl skeleton represented by the following general formula and other ligands and transition metal atoms are The thing which forms a ring is also mentioned.

[0024]

[Formula 1]

In the formula, Cp is a ligand having the cyclopentadienyl skeleton, X is hydrogen, halogen, and a carbon number of 1 to 2.
0 represents an alkyl group, an arylsilyl group, an aryloxy group, an alkoxy group, an amido group, a silyloxy group, etc., and Y represents —O—, —S—, —NR—, —PR— or O.
A divalent neutral ligand selected from the group consisting of R, SR, NR ₂ , and PR ₂ , Z is SiR ₂ , CR ₂ , SiR ₂ SiR
₂ , CR ₂ CR ₂ , CR = CR, SiR ₂ CR ₂ , BR
₂ represents a divalent group selected from the group consisting of BR. However, R is hydrogen or an alkyl group having 1 to 20 carbon atoms, an aryl group, a silyl group, a halogenated alkyl group, a halogenated aryl group, or Y, Z or 2 from both Y and Z.
The one or more R groups are those that form a fused ring system. M represents a transition metal atom of Group IV of the periodic table.

Other examples of the transition metal compound of Group R of the periodic table represented by the formula 1 are (t-butylamido) (tetramethylcyclopentadienyl) -1,2-ethanediylzirconium dichloride, ( t-butylamide)
(Tetramethylcyclopentadienyl) -1,2-ethanediyl titanium dichloride, (methylamido) (tetramethylcyclopentadienyl) -1,2-ethanediyl zirconium dichloride, (methylamido) (tetramethylcyclopentadienyl) -1,2-ethanediyl titanium dichloride, (ethylamido) (tetramethylcyclopentadienyl) methylenetan dichloride,
(T-Butylamido) dimethyl (tetramethylcyclopentadienyl) silane titanium dichloride, (t-butylamido) dimethyl (tetramethylcyclopentadienyl) silane zirconium dibenzyl, (benzylamido) dimethyl (tetramethylcyclopentadienyl) Examples thereof include silane titanium dichloride and (phenylphosphide) dimethyl (tetramethylcyclopentadienyl) silane titanium dichloride.

The cocatalyst referred to in the present invention can effectively use the transition metal compound of Group IV of the periodic table as a polymerization catalyst, or can balance the ionic charge in a catalytically activated state. Specific examples of the cocatalyst include benzene-soluble aluminoxanes of organoaluminum oxy compounds, organoaluminum oxy compounds insoluble in benzene, boron compounds, lanthanoid salts such as lanthanum oxide, and tin oxide. Of these, aluminoxane is most preferable.

The catalyst may be used by supporting it on an inorganic or organic carrier. The carrier is preferably a porous oxide of an inorganic compound or an organic compound, specifically, Si
O ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , B _{2
O 3, CaO, ZnO, BaO} , listed or ThO ₂ and the like or mixtures _{thereof, SiO 2 -Al 2 O 3,} SiO
_{2 -V 2 O 5, SiO 2} -TiO 2, SiO 2 -V 2 O
₅ , SiO ₂ —MgO, SiO ₂ —Cr ₂ O _{3 and the} like. Among these, those containing, as a main component, at least one component selected from the group consisting of SiO ₂ and Al ₂ O ₃ . Further, as the organic carrier, any of thermoplastic resin and thermosetting resin can be used, and specifically, particulate polyolefin, polyester, polyamide, polyvinyl chloride, poly (meth) acrylate,
Examples thereof include polystyrene, polynorbornene, various natural polymers, and mixtures thereof.

As the organoaluminum compound of the present invention,
Trialkyl aluminums such as triethyl aluminum and triisopropyl aluminum; dialkyl aluminum halides; alkyl aluminum sesquihalides;
Alkyl aluminum dihalide; alkyl aluminum hydride, organic aluminum alkoxide and the like can be mentioned.

The ethylene (co) polymer (B) of the present invention is
In the presence of the catalyst, it is produced by a gas phase polymerization method, a slurry polymerization method, a solution polymerization method or the like substantially without a solvent, butane, pentane, hexane, heptane are substantially cut off with oxygen, water and the like. And the like, and aromatic hydrocarbons such as benzene, toluene, and xylene, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane. The polymerization conditions are not particularly limited, but the polymerization temperature is usually 15 to 350 ° C,
Preferably 20 to 200 ° C., more preferably 50 to 1
The polymerization pressure is usually from normal pressure to 7 in the case of low and medium pressure method.
0 kg / cm ² G, preferably normal pressure to 20 kg / cm ²
G, which is preferably 1500 kg / cm ² G or less in the case of the high pressure method. The polymerization time is usually 3 minutes to 1 in the case of the low and medium pressure method.
0 hours, preferably about 5 minutes to 5 hours is desirable. In the case of the high pressure method, it is usually 1 minute to 30 minutes, preferably 2 minutes to 20 minutes. Also, the polymerization is of course a one-step polymerization method,
There is no particular limitation such as a two-step or more multi-stage polymerization method in which the polymerization conditions such as hydrogen concentration, monomer concentration, polymerization pressure, polymerization temperature and catalyst are different from each other.

The specific ethylene (co) polymer (B) of the present invention obtained with the above catalyst has a (b) density of 0.86 to 0.
97 g / cm ³ , preferably 0.89 to 0.95 g / c
m ³ , more preferably in the range of 0.90 to 0.94 g / cm ³ . If the density is less than 0.86 g / cm ³ , the rigidity is
The heat resistance is inferior, and impact resistance (low temperature embrittlement temperature) is insufficient at 0.97 g / cm ³ or more. In particular, 0.90-0.
Within the range of 94 g / cm ³ , a sheet pallet having a balance of rigidity, heat resistance and impact resistance can be obtained. The (c) melt flow rate of the ethylene (co) polymer (B) is 0.01 to 50 g / min, preferably 0.03 to.
The range is 30 g / min, more preferably 0.1 to 15 g / 10 min. If the MFR is less than 0.01, the moldability will be poor, and if it is 50 or more, the strength will be reduced.

Furthermore, the (d) molecular weight distribution parameter (Mw / Mn) of the ethylene (co) polymer (B) is 1.8.
To 3.5, preferably 2.0 to 3.0, and more preferably 2.2 to 2.8. Mw / M
When n is less than 1.8, the moldability is poor, and when it is 3.5 or more, the impact resistance is poor. When Mw / Mn is in the above range, mechanical strength such as impact strength is remarkably excellent as compared with the conventional ethylene polymer (C). Molecular weight distribution (Mw / M) of ethylene (co) polymer (B) of the present invention
The calculation method of n) is to determine the weight average molecular weight (Mw) and the number average molecular weight (Mn) by gel permeation chromatography (GPC), and to determine this Mw / Mn.

The (e) composition distribution parameter Cb of the ethylene (co) polymer used in the component (B) of the present invention is 1.
It is 2 or less, preferably 1.15 or less, and more preferably 1.1 or less. If it is 1.2 or more, there is a possibility that the effect of remarkably improving the mechanical strength of the ethylene (co) polymer as the component (B) cannot be expected.

The method for measuring the composition distribution parameter of the ethylene (co) polymer used as the component (B) of the present invention is as follows. A heat resistance stabilizer is added to the sample, and the sample is heated and dissolved in ODCB at 135 ° C. to a concentration of 0.2% by weight. The solution is transferred to a column packed with diatomaceous earth (Celite 545) and cooled to 25 ° C at 0.1 ° C / min to deposit a sample on the surface of Celite. Next, while flowing ODCB at a constant flow rate, the column temperature is raised stepwise to 120 ° C. in steps of 5 ° C. to elute the sample and separate the sample. The solution is reprecipitated with methanol, filtered and dried to obtain a sample at each elution temperature. Weight fraction and branching degree of each sample (100 carbon atoms)
The number of branches per 0) is measured. The degree of branching (measured value) is measured and determined by 13 C-NMR.

The degree of branching is corrected as follows for each of the fractions collected at 30 ° C to 90 ° C. That is, the measured branching degree is plotted against the elution temperature, and the correlation is approximated to a straight line by the method of least squares to create a calibration curve. The correlation coefficient of this approximation is sufficiently large. The value obtained from this calibration curve is the branching degree of each fraction. If the elution temperature is 95 ° C. or higher, a linear relationship does not always hold between the elution temperature and the degree of branching, so this correction is not performed.

Next, the weight fraction w of each fraction
_i is the amount of change in the branching degree b _i per elution temperature of 5 ° C. (b _i
-Bi _-1 ) to obtain the relative concentration c _i , and plot the relative concentration against the branching degree to obtain a composition distribution curve. This composition distribution curve is divided by a certain width, and the composition distribution parameter Cb is calculated by the following formula.

[0037]

[Formula 2]

Here, C _j and b _j are the relative density and branching degree of the j-th section, respectively. Composition distribution parameter C
b is 1 when the composition of the sample is uniform, and increases as the composition distribution spreads.

Many proposals have been made for a method of measuring the composition distribution of a polymer. For example, JP-A-60-88016
In No. 6, the sample was subjected to solvent fractionation, and numerical processing was performed on the assumption that the cumulative weight fraction has a specific distribution (logarithmic normal distribution) with respect to the number of branches of each fractionated sample.
The ratio between w) and the number average branching degree (Cn) is calculated. The accuracy of this approximate calculation is low when the number of branches of the sample and the cumulative weight fraction deviate from the lognormal distribution, and the correlation coefficient R ² is considerably low when the measurement is performed on commercially available LLDPE, and the accuracy of the value is not sufficient. The Cw / Cn measuring method and numerical processing method are different from those of Cb of the present invention, but if the values are compared, the value of Cw / Cn becomes considerably larger than that of Cb.

The specific ethylene (co) polymer (B) of the present invention has a uniform active site of the catalyst so that the molecular weight distribution and the composition distribution are narrowed and the impact strength is excellent. These polymers have properties different from those of the ethylene / α-olefin copolymer as the component (C) obtained by conventional Ziegler type catalysts and Phillips type catalysts (hereinafter collectively referred to as Ziegler type catalysts). .

The ethylene polymer (C) component forming the composition of the present invention is roughly classified into two types, and the first component (C1) is the Ziegler type catalyst or Phillips type catalyst by the conventional ionic polymerization method. Density of 0.86 to 0.97 g obtained with a catalyst (hereinafter collectively referred to as Ziegler type catalyst)
/ Cm ³ ethylene polymer or ethylene / α-olefin copolymer, and specifically, high density polyethylene (HDPE), linear medium density polyethylene (MDPE),
Examples include linear low density polyethylene (LLDPE) and ultra-low density polyethylene (VLDPE).

High density / linear medium / low density polyethylene (HDPE, MDPE, LLD) produced by the above Ziegler type catalyst
PE) has a density in the range of 0.91 to 0.97 g / cm ³ , preferably 0.91 to 0.96 g / cm ³ , and M
FR is 0.05 to 20 g / 10 min, preferably 0.
1 to 10 g / 10 min, more preferably 0.3 to 1
It is selected in the range of 0 g / 5 min. Mw / Mn is not particularly limited, but is generally in the range of 3.0 to 13, preferably 3.5 to 8. The composition distribution is not particularly limited, but it is generally 1.5 or more, preferably 2.0 or more.

The ultra-low density polyethylene (VLDPE) using the above Ziegler type catalyst has a density of 0.86 to
Less than 0.91 g / cm ³ , preferably 0.88 to 0.9
05 g / cm ³ , MFR 0.01 to 20 g / 10 mi
n, preferably 0.1 to 10 g / 10 min. The ultra low density polyethylene (VLDPE) is
Linear low density polyethylene (LLDPE) and ethylene
It exhibits properties intermediate to those of the α-olefin copolymer rubber (EPR, EPDM) and has a maximum peak temperature (Tm) of 60 ° C. or higher, preferably 1 by differential scanning calorimetry (DSC).
Above 00 ° C and 10% by weight of boiling n-hexane insoluble matter
A specific ethylene / α-olefin copolymer having the above properties, which is polymerized using a catalyst composed of a solid catalyst component containing at least titanium and / or vanadium and an organic aluminum compound, and is a linear low-density polyethylene. It is a resin that has both the highly crystalline portion shown by and the amorphous portion shown by the ethylene / α-olefin copolymer rubber, and the former features such as mechanical strength and heat resistance, and the latter feature like rubber. Elasticity and low temperature impact resistance coexist in a well-balanced manner.

Ethylene / α with the above Ziegler type catalyst
-The α-olefin of the olefin copolymer has a carbon number of 3 to 12, preferably 3 to 10, specifically, propylene, butene-1,4-methylpentene-
1, hexene-1, octene-1, decene-1, dodecene-1 and the like. The content of these α-olefins is preferably selected in the range of 3 to 40 mol%.

The second component (C2) of the ethylene polymer of the present invention is low density polyethylene (LDPE) produced by high pressure radical polymerization, an ethylene / vinyl ester copolymer,
It is a copolymer of ethylene and an α, β-unsaturated carboxylic acid or its derivative.

The above low density polyethylene (LDPE) is
MFR (melt flow rate) of 0.05 to 20g / 1
The range is 0 min, preferably 0.1 to 10 g / 10 min, and more preferably 1.0 to 10 g / 10 min. Within this range, the melt tension of the composition will be in an appropriate range, and sheet formation and the like will be easy. The density is 0.91 ~
0.94 g / cm ³ , preferably 0.912 to 0.93
5 g / cm ³ , more preferably 0.912 to 0.93
It is 0 g / cm ³ . Further, Mw / Mn is 3.0 to 1
2, preferably 4.0 to 8.0.

The ethylene / vinyl ester copolymer of the present invention is a vinyl propionate, vinyl acetate, vinyl caproate, vinyl caprylate, vinyl laurate, stearic acid containing ethylene as a main component, which is produced by a high pressure radical polymerization method. It is a copolymer with vinyl ester monomers such as vinyl and trifluorovinyl acetate. Of these, vinyl acetate is particularly preferable. That is, a copolymer composed of 50 to 99.5% by weight of ethylene, 0.5 to 50% by weight of a vinyl ester, and 0 to 49.5% by weight of another copolymerizable unsaturated monomer is preferable. Particularly, the vinyl ester content is in the range of 3 to 20% by weight, preferably 5 to 15% by weight. The MFR of these copolymers is 0.1 to 20 g / 10 min, preferably 0.3 to 10 g / 10 min.

Typical examples of the copolymer of ethylene of the present invention with α, β-unsaturated carboxylic acid or its derivative are:
Examples thereof include ethylene / (meth) acrylic acid or an alkyl ester copolymer thereof, and as these comonomers, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, Propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, -n-butyl acrylate, -n-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, Examples thereof include glycidyl acrylate and glycidyl methacrylate. Among these, (meta) is particularly preferable.
Examples thereof include alkyl esters of acrylic acid such as methyl and ethyl. In particular, the (meth) acrylic acid ester content is preferably in the range of 3 to 20% by weight, particularly 5 to 15% by weight. The MFR of these copolymers is 0.1
~ 20g / 10min, preferably 0.3-10g / 1
It is 0 min.

The composition of the sheet pallet of the present invention is such that the component (A) is 50 to 95% by weight, preferably 60 to 93% by weight, more preferably 65 to 87% by weight, and the component (B) is 5 to 50% by weight.
%, Preferably 7 to 40% by weight, more preferably 13 to 35% by weight, and up to 45% by weight of component (C), preferably 35% by weight or less, more preferably 30% by weight or less. When heat resistance and the like are emphasized, it is preferable that the composition is composed of two components, component (A) and component (B), but in consideration of cold resistance, workability, and economy, (C)
It is desirable to incorporate up to 45% by weight of the components. If the content of the component (A) is less than 50% by weight, the rigidity of the sheet is lowered, and if the content of the component (B) is less than 5% by weight, the low temperature impact resistance is not improved. Further, the component (C) is 45% by weight.
If it exceeds, mechanical strength characteristics such as tensile strength may not be improved. The target value of the properties of the compounded composition used in the present invention is a flexural rigidity of 5000 kg / cm ² or more,
Preferably 5500kg / cm ² or more, more preferably at 6000 kg / cm ² or more, brittle temperature -50 ° C.
Hereafter, it is preferably −55 ° C. or lower.

Any known technique can be used as a method for compounding the above three components (A), (B) and (C), and typical examples thereof include a normal kneader such as a Henschel mixer, an extruder and a tumbler. It is carried out by a method such as dry blending and melt mixing. In the present invention, after the components (A), (B) and (C) are mixed in a desired ratio as described above, the sheet is formed by a usual method such as extrusion molding (for example, T die method) or calendering method.

All or a desired portion of the upper surface of the sheet is roughened by subjecting it to surface treatment such as embossing, sandblasting, corona discharge treatment, flame treatment, plasma treatment or the like, or an ethylene-vinyl acetate copolymer is formed on the upper surface of the sheet. By laminating or stacking anti-slip material such as synthetic rubber, the coefficient of friction of the upper surface is made larger than the coefficient of friction of the lower surface of the seat to prevent slipping or slipping of the load. The coefficient of friction varies depending on the cargo packaging material such as paper or plastic, the shape of the cargo bottom, the weight of the cargo, etc. ~ 0.8, preferably 0.3 ~
A range of 0.7 is suitable. In order for the upper surface of the sheet to be in the range of the coefficient of friction described above, when the sheet is roughened by, for example, embossing, the surface roughness R, which is the degree of embossing.
max is 10 to 300 μm, preferably 20 to 200 μm
m, and more preferably 30 to 150 μm. In addition,
Rmax is the maximum value of the peak-valley difference on the rough surface.

The sheet pallet of the present invention has a thickness of 0.3.
It is appropriately selected within the range of 10 to 10 mm, preferably 0.5 to 5 mm, and more preferably 0.8 to 2.5 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 poor, and the thickness is 10 m.
When it exceeds m, the characteristics required in the present invention are satisfied, but the weight becomes large, and there is a concern that automation and handling of cargo handling may be hindered. The sheet pallet of the present invention may have any suitable shape such as a rectangle, a square, an ellipse, and a circle.

The present invention also provides various fillers such as carbon black, calcium carbonate, silica, metal fibers, or antioxidants, flame retardants, and the like in the sheet material during melt mixing.
Ordinary additives such as colorants, antistatic agents, lubricants, ultraviolet absorbers and dispersants may be blended as necessary.

[0054]

As described above, the sheet pallet of the present invention uses the propylene-based polymer, the specific ethylene (co) polymer, and the blended composition of the ethylene-based polymer to improve the water resistance, the oil resistance and the resistance to oil. Not only does it have good chemical properties such as chemical properties and can withstand repeated use, but it also has a much better balance of strength, rigidity, heat resistance, and low temperature impact resistance than conventional products. The characteristics are improved and it can be used for a long time without trouble.

[0055]

EXAMPLES The present invention will be specifically described below based on Examples and Comparative Examples, but the present invention is not limited thereto.

(Examples 1 to 7, Comparative Examples 1 to 7) The following were used as the components A), B) and C). Component A): (A) Polypropylene block copolymer (ethylene content 11% by weight, MFR 1.5 g / 10 min)

Component B): <Polymerization of ethylene / α-olefin copolymer> B1) Polymerization of ethylene / butene-1 copolymer A 3 L stainless steel autoclave equipped with a stirrer is replaced with nitrogen to purify 1.5 L. Toluene was added. Next, 10 g of butene-1 was added, and bis (n-butylcyclopentadienyl) zirconium dichloride (Z
0.02 mmol as r) methylalumoxane [MA
O] (MAO / Zr = 500 [molar ratio]) was added, and the temperature was raised to 80 ° C. Next, ethylene was supplied to carry out polymerization while continuously maintaining the pressure constant. The physical properties of the obtained ethylene / butene-1 copolymer were as follows. MFR: 1.9 g / 10 min Density: 0.9238 g / cm ³ Melting point: 116 ° C. Molecular weight distribution (Mw / Mn): 2.1 Composition distribution: 1.03

B2) Polymerization of ethylene / octene-1 copolymer A 3 L stainless steel autoclave equipped with a stirrer was purged with nitrogen and charged with 1.5 L of purified toluene. Next, 150 ml of octene-1 was added and heated to 140 ° C. Next, add ethylene to 30 kg / cm ² G,
Then dissolved in toluene (tert-butyramide)
Dimethyl (tetramethylcyclopentadienyl) silane zirconium dichloride (0.02 mmol as Zr) methylalumoxane [MAO] (MAO / Zr = 5
00 (molar ratio)), and then the temperature was raised to 80 ° C. Next, ethylene was supplied to carry out polymerization while continuously maintaining the pressure constant. The physical properties of the obtained ethylene / octene-1 copolymer were as follows. MFR: 2.1 g / 10 min Density: 0.9258 g / cm ³ Melting point: 109 ° C. Molecular weight distribution (Mw / Mn): 3.8 Composition distribution: 1.08

C1: Ziegler-catalyzed linear low density polyethylene (density = 0.925 g / cm ³ , MFR =
2.0 g / 10 minutes, Mw / Mn = 4.3, composition distribution =
1.6, trade name: Nisseki Linirex, manufactured by Nippon Petrochemical Co., Ltd. C2: Ziegler-catalyzed ultra-low density polyethylene (density = 0.905 g / cm ³ , MFR = 1.0 g / 10)
Min, trade name: Nisseki Softlex, D9510 manufactured by Nippon Petrochemical Co., Ltd. C3: Ziegler-catalyzed high-density polyethylene (density = 0.954 g / cm ³ , MFR = 0.3 g / 10 min,
Product name: Nisseki Staflen, E803 manufactured by Nippon Petrochemical Co., Ltd. C4: Low density polyethylene by high pressure radical polymerization (density = 0.924 g / cm ³ , MFR = 1.0 g / 10)
Min, product name: Nisseki Lexron, F22 manufactured by Nippon Petrochemical Co., Ltd.

The components A), B) and C) are dry blended in a predetermined ratio, and then the extruder (120) is used.
mmφ), resin temperature 235 ° C., chill roll temperature 1
A sheet having a thickness of 1.8 mm and a width of 1600 mm was extruded under a sheet forming condition of 00 ° C. and a take-up speed of 2 mm / min, and the upper surface of the sheet was embossed to produce a sheet pallet material. Table 1 shows the composition and properties of the above various sheet pallet materials. The method for measuring the property values is as follows. Bending stiffness: JIS K7106 Brittleness temperature: JIS K6760 Static friction coefficient: Inclined plate method (cardboard / sheet surface)

As is clear from Table 1, in each of the examples of the present invention, the flexural rigidity and tensile strength are high, and the brittleness temperature is sufficiently low, and the rigidity and low temperature impact resistance are well balanced. There is. On the other hand, in the case of Comparative Example, the balance of these properties was not sufficient, and both could not be satisfied at the same time.

[0062]

[Table 1]

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Claims (2)

(57) [Claims] 1. A (A) propylene polymer 50 to 95
In the presence of a catalyst containing, by weight, (B) (a) a ligand having a cyclopentadienyl skeleton, a transition metal compound of Group IV of the periodic table as an essential component, ethylene or ethylene and a carbon number of 3 to (B) Density obtained by (co) polymerizing 20 α-olefins is 0.86 to 0.97 g / c.
m ³ , (c) Melt flow rate is 0.01 to 50 g /
10 minutes, (d) molecular weight distribution parameter Mw / Mn1.
5 to 50% by weight of an ethylene (co) polymer having a composition distribution parameter Cb of 1.2 or less in the range of 8 to 3.5, and (C) an ethylene polymer other than the component (B). ~ 45
% Of the composition (provided that the total amount of components (A), (B) and (C) is 100% by weight), the coefficient of friction of the upper surface is greater than the coefficient of friction of the lower surface, and the thickness is A sheet-shaped cold-resistant sheet pallet having a thickness of 0.3 to 10 mm. 2. The (C) ethylene polymer is the following:
The cold-resistant sheet pallet according to claim 1, which is at least one selected from ethylene (co) polymers of (C1) and (C2) . (C1) Ethylene / α-olefin copolymer having a density of 0.86 to 0.97 g / cm ³ (C2) Low density polyethylene by high pressure radical polymerization,
Ethylene / vinyl ester copolymer, ethylene and α, β
-Copolymers with unsaturated carboxylic acids or their derivatives