JPH0759642B2 - Non-chargeable tear sheet with excellent durability - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tear sheet for conveying a container.

More specifically, the present invention relates to a tear sheet composed of a blended composition mainly containing an olefin polymer and conductive fibers.

[Conventional technology]

In recent years, metal containers such as steel or aluminum used for beer, soft drinks, edible oil, canned food, etc.
A large variety of containers such as glass containers used for sake, beer, milk, vinegar, liquid seasonings, pharmaceuticals, industrial chemicals, and plastic containers used for liquid detergents, soft drinks, seasonings, etc. It is used. Most of the cargo handling work such as packing and transportation of these containers is mechanized or automated.

As one mode of the above-mentioned packing and transportation, there is unit loading. In this method, when packing and transporting containers, etc., these are put together in an appropriate number or weight to make one unit,
This is a method in which cargo is handled as a single unit without being broken down on the way.

That is, a certain number of containers are stacked on a pallet in multiple rows in multiple stages to be unitized, and then used for cargo handling work such as shrink wrapping and stretch wrapping.When stacking containers in multiple tiers for unitization, For the purpose of stabilizing the container, preventing the collapse of cargo, and preventing bacteria and dust, a tear sheet is inserted at each stage.

At present, a paper board is generally used as this tear sheet, but it cannot be used repeatedly because its mechanical strength such as bending rigidity and impact resistance decreases due to water absorption, moisture absorption, etc. There was a restriction. In addition, since the material is paper, there are drawbacks such that fluffing occurs and various bacteria and dust are easily attached. In addition, since it cannot be washed with water or treated with hot water, it cannot be sufficiently sterilized and dust-proofed by washing with air shower, brushing, sterilization such as flame treatment, hot roll treatment, etc. When palletizing, transporting, etc., it is unavoidable that these germs are mixed in the container, and there is a problem in using a paper tear sheet especially in the fields of food, medicine and the like.

As a means for solving such a problem, a plastic tear sheet made of a random copolymer of 2 to 10% ethylene and 90 to 98% propylene has been proposed (International Publication No. W082 / 01861).

However, since this tear sheet has poor heat resistance, it easily deforms due to thermal deformation during shrink wrapping,
In addition, since it is made of plastic, there is a problem that it is significantly charged and easily attracts dust and easily causes troubles.

As a general method for solving the above-mentioned problem of charging, various methods of compounding an antistatic agent, carbon black, etc. have been proposed. However, in the method of blending the above-mentioned antistatic agent, the antistatic agent is water-soluble, so that when the tear sheet is washed with water, the antistatic agent is washed away with water and the antistatic effect is lowered, and the antistatic agent in the tear sheet is washed. Even if the inhibitor bleeds again, the recovery time during that time is long, which is inconvenient, and the antistatic property cannot be imparted permanently.

In addition, although the method of blending carbon black has an antistatic effect, the tear sheet becomes completely black, so that its use is limited in fields requiring hygiene such as pharmaceuticals and foods. Further, there is a problem that the extruder and the environment are polluted. Methods such as coating and dipping an antistatic agent solution have also been proposed, but all of them have poor antistatic durability.

[Problems to be Solved by the Invention]

The present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to provide a tear sheet having the following performance in addition to the performance of the conventional tear seat.

A first object of the present invention is to provide a tear sheet which is excellent in water resistance and moisture resistance, has a mechanical strength that can withstand repeated use, is excellent in heat resistance, and has mechanical aptitude that does not cause thermal deformation during shrink packaging.

A second object is to provide a tear sheet which has excellent antistatic effect durability, can be washed with water, can be sterilized at high temperature, can be colored, and is clean in terms of food hygiene and excellent in appearance. It is in.

[Means for Solving the Problems]

The tear sheet of the present invention is composed of a composition mainly containing a mixture of an olefin polymer and a conductive fiber, and has a surface resistivity of 10 ¹⁰ Ω or less and a thickness of 0.3 to ¹⁰ mm consisting of a sheet-like product having durability. It is an excellent non-chargeable tear sheet and has an excellent feature in that it can be colored.

Examples of the olefin polymer include low, medium and high density polyethylene, polypropylene, polybutene-1, poly-4.
Examples include homopolymers such as methylpentene-1, polyolefin resins such as copolymers containing ethylene or propylene as a main component with other α-olefins, and mixtures thereof.

From the viewpoint of heat resistance, flexural rigidity, mechanical strength such as impact resistance, etc., a crystalline polymer or an ethylene polymer composed of an olefin having 3 or more carbon atoms, or a polymer thereof and another olefin polymer A mixture is preferable, and a propylene-based polymer composed of a propylene homopolymer or a block copolymer or a mixture thereof, or a mixture of these propylene-based polymers and ethylene-based polymers is particularly preferable. The above mixing ratio is 50 to 95% by weight of the propylene-based polymer and 50 to 5% by weight of the ethylene-based polymer. If the mixing ratio of the propylene-based polymer is less than 50% by weight, the heat resistance may decrease, and if it exceeds 95% by weight, the impact resistance may decrease. Therefore, it is preferable to balance these physical properties.

Further, in order to improve impact resistance, particularly low temperature impact properties, etc., if necessary, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, butyl rubber, polyisobutylene, etc. may be added to the above polymers. Elastomers such as synthetic rubber and natural rubber can be mixed.

The MFI (melt flow index) of the propylene polymer is preferably in the range of 0.1 to 10 g / 10 min. If the MFI is less than 0.1 g / 10 min., The flowability of the molten resin is poor, and it is difficult to produce a good sheet. If the MFI is more than 10 g / 10 min., The web of the molten resin sags and good molding is also difficult. In addition, there is a concern that the strength and other physical properties of the sheet may deteriorate.

As the conductive fiber of the present invention, carbon fiber, metal fiber made of aluminum, brass, stainless steel, etc., metallized glass fiber obtained by coating glass fiber with silver, copper, etc., fine metal powder such as silver, copper, brass, tin, etc. Examples include mixed synthetic fibers. Among these, carbon fiber is most preferable from the viewpoint of performance and economy. Also, the diameter of the conductive fiber is 5 to 15 from the viewpoint of the mechanical strength of the tear sheet.
A relatively small value of μ is preferable, and a fiber length of 0.1 to 10 mm is preferable in terms of surface resistance.

The content of the conductive fiber is 5 to 30 parts by weight, preferably 7 to 15 parts by weight, based on 100 parts by weight of the olefin polymer. If the fiber content is less than 5 parts by weight, the surface resistivity of the tear sheet exceeds 10 ¹⁰ Ω and the antistatic effect cannot be satisfied. On the other hand, if it exceeds 30 parts by weight, the antistatic effect can be satisfied, but the tear sheet becomes dark and the appearance is deteriorated.

The inorganic filler used in the present invention is in the form of powder, tabular, or scaly, needle-like, spherical or hollow, fibrous, fibrous woven, and the like, and specific examples thereof include carbonic acid. Calcium, magnesium carbonate, calcium sulfate, calcium silicate, barium sulfate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, calcium sulfite, mica, clay, diatomaceous earth, talc, zeolite, zinc oxide, titanium oxide, molybdenum sulfide , Quartz powder, bentonite, alumina, silica sand, iron oxide,
Metal powder, antimony trioxide, graphite, silicon carbide,
Powder / granular filler such as silicon nitride, silica, boron nitride, aluminum nitride, white carbon, carbon black, glass beads, glass powder, silica stone, mica, glass plate,
Metallic foils such as sericite, pyrophyllite, aluminum flakes, flat or scale-like fillers such as graphite, hollow fillers such as shirasu balloons, metal balloons, glass balloons and pumice, glass fibers, whiskers, silicon carbide fibers Examples thereof include fibrous fillers such as mineral fibers such as asbestos, asbestos and wollastonite.

Among these, talc is the most preferable from the viewpoint of comprehensive mechanical properties such as heat resistance and bending elastic modulus, and workability, and the particle size is preferably in the range of 2 to 10 μm. If the particle size exceeds 10 μ, there is a concern that the impact strength may decrease, and if it is less than 2 μ, it is preferable in terms of physical properties, but it is expensive and economically disadvantageous.

The blending amount of the above-mentioned inorganic filler can be appropriately selected within the range of 5 to 30 parts by weight with respect to 100 parts by weight of the olefin polymer. When the compounding amount of the inorganic filler is less than 5 parts by weight, the required physical properties such as heat resistance cannot be satisfied. Meanwhile, 30
If the amount is more than parts by weight, the mechanical strength may decrease, which is not preferable.

In particular, in the present invention, various colorable tear sheets can be obtained by blending a hiding agent such as titanium dioxide.

The compounding amount of the above-mentioned hiding agent is preferably in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the olefin polymer.

Further, in the present invention, when the tear sheet raw material is blended, in order to improve the kneading property and the moldability of the tear sheet, and also the weather resistance, bending rigidity, impact resistance, heat resistance and color tone, gloss of the tear sheet, In order to improve surface properties such as scratch resistance, printability and paintability, ordinary additives such as antioxidants, UV absorbers, dispersants, lubricants, cross-linking agents, organic or inorganic pigments are added. It doesn't matter.

The tear sheet raw material can be compounded using a kneading machine such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll or a kneader, and can be easily formed into a sheet by using an ordinary T-die extruder. can do.

The thickness of the sheet of the present invention is 0.3 to 10 mm, preferably 0.5 to
A range of 5 mm is suitable. If the thickness is less than 0.3 mm, the mechanical strength such as bending rigidity of the sheet is not sufficient, and if it exceeds 10 mm, the weight of the sheet becomes large, which may hinder automation and handling of luggage.

The surface of the tear sheet of the present invention may be roughened by subjecting one or both sides to surface treatment such as embossing, sand plast, corona discharge treatment, flame treatment and plasma treatment. However, depending on the type of metal container, glass container, plastic container, etc., the weight of the container, the shape of the container bottom, etc. and how to handle the tear sheet, etc., it is generally impossible to say that the surface is a mirror surface. Since the area of contact with the container is large and the coefficient of friction is also larger than the rough surface, it is preferable that at least one surface is a mirror surface, and preferably both surfaces are mirror surfaces, in order to prevent collapse of the load.

In addition, the surface of the tear sheet is to improve mechanical strength such as bending rigidity in one direction, or to adjust the contact area with the container to give directionality when arranging the containers on the tear sheet. In addition, fine ruggedness may be applied when forming the tear sheet.

The shape of the tear sheet of the present invention may be an appropriate shape such as a rectangle, a square, an ellipse, and a circle. However, in the case of a shape having a corner such as a rectangle or a square, each corner has a round shape suitable for the shape of the container. It is desirable to attach. Also,
Holes for draining can be formed in desired portions of the tear sheet to the extent that required physical properties such as bending rigidity are not impaired.

The tear sheet of the present invention described above is suitable for stacking containers in multiple stages, and has bending rigidity and mechanical strength such as impact resistance suitable for each working process such as palletizing and depalletizing. Further, since it has excellent heat resistance, there is no thermal deformation that would hinder the shrink wrapping work, and high temperature sterilization can be performed.
Further, since it is excellent in water resistance and moisture absorption resistance, there is no reduction in mechanical strength due to water absorption / moisture absorption, and washing with water and sterilization with hot water are possible. Since the antistatic effect is excellent in durability, it is difficult for dirt and bacteria to attach and drop off easily. Therefore, a tear sheet that is not only durable for repeated use but also always clean is provided. Therefore, it is possible to provide a tear sheet which has an effect of protecting various bacteria, dust and the like from the unfilled container and is excellent in food hygiene.

〔Example〕

 The present invention will be described in more detail below with reference to examples.

Example 1 Polypropylene homopolymer (MFI = 1.0 g / 10 min. Trade name:
Nisseki Polypro J120 Nippon Petrochemical Co., Ltd. 100 parts by weight,
Talc (trade name: PK-C, manufactured by Hayashi Kasei Co., Ltd., average particle size 10
μ, water content 0.13%, white scale-like) 5 parts by weight <10 parts by weight of carbon fiber (trade name: Granock, Nippon Oil Co., Ltd., diameter 7 μ, fiber length 0.2 mm) and titanium dioxide (rutile specified in JIS K5116) Type 1) 0.5 part by weight of twin-screw extruder (diameter 6
5mm) and then T-die extruder (diameter 90mm), resin temperature 240 ℃, chill roll temperature 70 ℃, take-up speed 1.5m / mi
A sheet having a thickness of 1.0 mm and a width of 1500 mm was formed, and a tear sheet having a radius of 1440 mm × 1130 mm and 25 mm at each corner was obtained from this sheet.

Unfilled 350ml beer cans are arranged in a row of 21 rows × 19 rows on a plastic pallet on a double-sided mirrored tear sheet, and the tear sheet is inserted and similarly loaded.
Stack the tiers, place the tear sheet on the top can, and then place the plastic top plate on it. This was taken as one unit and the deformation of the tear sheet was observed when shrink-wrapped at 160 ° C for 1 minute. Further, the basic physical properties of tear sheet were tested in accordance with the following test methods, and the results are shown in Table 1.

Also, the durability of the tear sheet was evaluated by a dipping test and a heat cycle test, and the result was evaluated as the second
The results are shown in Tables and Table 3.

Test item Test method Tensile test JIS K6911 Flexural modulus JIS K7203 Izod impact strength (with notch) JIS K7110 Heat distortion temperature (4.6 kg) ASTM D648 Surface resistivity JIS K6911 Ash 30 g rubbed with cotton gauze and dried tobacco ash Visually observe the degree of adhesion of.

(Judgment criteria) ○: No adhesion.

Δ: A small amount adheres.

X: A large amount adheres.

Deformation status of tear sheet after shrink wrapping: At 160 ° C for 1 minute, the deformation status of the tear sheet after shrink wrapping and the shrinking force of the shrink film are observed.

Immersion test After dipping a 150mm x 150mm test piece in a hot water bath at 90 ° C for 5 minutes,
The test variation was taken out, and the operation of air cooling was repeated 50 times, and then the surface resistivity surface was measured.

Heat cycle test Unfilled coffee can (250g) on 300mm x 300mm test piece
Are arranged and loaded in 6 rows × 6 rows, and a test piece having the same size as the above-mentioned test piece is inserted and similarly loaded.

Place the test piece on it and place the base plate with a load of 10 kg.

This is set as 1 unit, left in an air oven at 160 ° C for 2 minutes, then taken out and air-cooled, repeated 50 times,
The state of deformation due to heating was observed.

The test pieces used in the above test were prepared by injection molding using the tear sheet as it was for the bending test and the ash, and crushing the tear sheet for the other test pieces.

Injection molding conditions Injection pressure 1000 kg / cm ² Injection time 15 sec Cooling time 20 sec Mold temperature 50 ° C. Resin temperature 270 ° C. Example 2 55 parts by weight of the polypropylene homopolymer used in Example 1 as an olefin polymer and a block copolymer. (MFI ＝
1.5g / 10min. Product name: Nisseki Polypropylene J725N, manufactured by Nippon Petrochemical Co., Ltd.) 45 parts by weight, 10 parts by weight of talc used in Example 1, 10 parts by weight of carbon fiber and titanium dioxide
0.5 part by weight was kneaded in the same manner as in Example 1 and formed into a sheet to obtain a tear sheet. The same tests as in Example 1 were conducted on the tear sheet, and the results are shown in Table 1.

Example 3 90 parts by weight of the polypropylene block copolymer used in Example 2 as an olefin polymer, 15 parts by weight of talc used in Example 1, 10 parts by weight of carbon fiber and 0.5 part by weight of titanium dioxide were used in Example 1 Kneading and sheet formation were carried out in the same manner as above to obtain a tear sheet. The tear sheet was tested in the same manner as in Example 1, and the results are shown in Table 1.

Example 4 As an olefin polymer, 80 parts by weight of the homopolymer of polypropylene used in Example 1 and high density polyethylene (MF
I = 0.3 g / 10 min. Product name: Nisseki Staflen E803, manufactured by Nippon Petrochemical Co., Ltd.) 10 parts by weight, 15 parts by weight of talc used in Example 1 and 10 parts by weight of carbon fiber are used as in Example 1. Was kneaded and molded into a sheet to obtain a tear sheet. The tear sheet was tested in the same manner as in Example 1 and the results are shown in Table 1.

Example 5 100 parts by weight of the polypropylene homopolymer used in Example 1 were kneaded with 10 parts by weight of carbon fiber and 2 parts by weight of titanium dioxide in the same manner as in Example 1 to form a sheet, and the same as in Example 1. Tests were conducted and the results are shown in Table 1.

Example 6 Sheet molding and evaluation were carried out in the same manner as in Example 5 except that the carbon fiber of Example 5 was replaced by stainless fiber and the compounding amount of titanium dioxide was 1 part by weight, and the results are shown in Table 1. Indicated.

Comparative Example 1 Only the polypropylene polymer used in Example 1 was sheet-formed in the same manner as in Example 1 to obtain a tear sheet. Table 1 shows the results of tests conducted on the tear sheet.

Comparative Example 2 100 parts by weight of the polypropylene polymer used in Example 1 and 10 parts by weight of talc were kneaded in the same manner as in Example 1 and sheet-formed to obtain a tear sheet. Table 1 shows the results of tests conducted on the tear sheet.

[Effects of the Invention] As can be seen from the above description and examples, the tear sheet of the present invention is rich in water resistance / moisture resistance, has mechanical strength to withstand repeated use, and further contains an inorganic filler such as talc. As a result, the heat resistance is improved, so that thermal shrinkage does not occur during shrink wrapping, which facilitates the work and thus provides a non-chargeable tear sheet having excellent durability.

Claims (7)

[Claims] 1. A composition mainly containing a mixture of an olefin polymer and a conductive fiber, having a surface resistivity of
A non-chargeable tear sheet with excellent durability consisting of a sheet-like material with a thickness of 0.3-10 mm at 10 ¹⁰ Ω or less. 2. The tear sheet according to claim 1, wherein the olefin polymer is a propylene polymer. 3. The tear sheet according to claim 1, wherein the olefin polymer comprises 50 to 95% by weight of a propylene polymer and 50 to 5% by weight of an ethylene polymer. 4. The tear sheet according to claim 1, wherein the composition contains an inorganic filler. 5. The tear sheet according to claim 4, wherein the inorganic filler is talc and is contained in an amount of 5 to 30 parts by weight based on 100 parts by weight of the olefin polymer. 6. The conductive fiber is a carbon fiber and / or a metal fiber, and is contained in 5 to 30 parts by weight based on 100 parts by weight of the olefin polymer. Tier sheet described in. 7. The tear sheet according to claim 1, wherein 0.1 to 5 parts by weight of titanium dioxide is blended as a hiding agent with 100 parts by weight of the olefin polymer. Tear sheet.