JPS626502B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to anti-slip polypropylene molded articles. More specifically, the present invention relates to a polypropylene molded product equipped with an anti-slip material that has an excellent anti-slip effect and good durability. Polyolefin molded products such as polypropylene have excellent water resistance and chemical resistance, are hygienic, and have uniform specifications for molded products, so they have come to be widely used in place of wood, metal, etc. However, although this polyolefin molded product has the above-mentioned excellent features, it also has the drawback of being slippery. Particularly when pallets used for transporting or storing cargo are made from polyolefin molded products, slipping may occur between the cargo and the pallet, between the pallet and fork such as a forklift, or between pallets. There is a risk of the cargo collapsing when transporting or transferring the cargo. Conventionally, methods to prevent the above-mentioned slipping have been used, such as creating irregularities on the surface of molded products such as pallets, or fitting rubber anti-slip fittings, but these methods have various problems. It's hard to say that I'm still satisfied with it. The inventors of the present invention have conducted intensive studies to solve the above-mentioned disadvantage of the slipperiness of conventional polypropylene molded products, and as a result, they have installed a polypropylene molded product using a non-slip material made of a special composition in a specific configuration. They discovered that the problem could be solved by doing this and completed the present invention. That is, the gist of the present invention is to heat-weld an anti-slip material formed by molding a mixture of ethylene propylene rubber and high-pressure low-density polyethylene having long chain branches in a weight ratio of 20:80 to 80:20 to a polypropylene molded product. It consists in a polypropylene molded product made of An example of the molded product of the present invention will be further explained below with reference to the drawings. FIG. 1 is a perspective view of a pallet which is an example of the molded product of the present invention. In the figure, 1 indicates a molded product (pallet), and 2 indicates a non-slip material. The synthetic resin constituting the molded product (pallet) 1 of the present invention is selected from consideration of thermal weldability with the anti-slip material 2, etc.
Polypropylene resin is used, but among them, the hardness (hardness according to JIS K 631) is JISA 97 or higher than 100.
It is preferable that it be close to . To put this more simply, a hard polyolefin containing polypropylene as a main component and having a Shore hardness (hardness according to ASTM D2240 Shore D) of 60 or more, preferably 70 or more is preferred. The polypropylene constituting the molded article 1 described above may contain additives such as antioxidants, ultraviolet absorbers, heat stabilizers, antistatic agents, flame retardants, crosslinking agents, foaming agents, dye pigments, organic fillers, and inorganic fillers. The agent may be added and mixed, and the molded product 1 may be molded by injection molding,
Conventional molding methods such as extrusion molding and cast molding can be used as desired depending on the desired molded product. When the molded product 1 is a pallet, it is desirable to add a foaming agent to the above-mentioned polypropylene to obtain a low-foaming injection molded product having a non-foamed layer on the surface layer at an expansion ratio of about 1.05 to 1.5 times. Of course, it may be non-foamed. The anti-slip material 2 is obtained by molding a blend of ethylene propylene rubber and high-pressure low density polyethylene having long chain branches. Ethylene propylene rubber is a rubber-like product obtained by polymerizing, for example, ethylene and propylene in the presence of a Ziegler catalyst. This ethylene propylene rubber has an ethylene component of 60 to 80% by weight, preferably 70 to 80% by weight.
It is desirable to contain 80% by weight. Furthermore, high-pressure low-density polyethylene having long chain branches is obtained by polymerizing ethylene alone or a mixture of ethylene and a small amount of a copolymer component using a high-pressure method, and has a density of 0.94 or less, preferably 0.925.
These are as follows. In addition, the melt index (190℃) is 0.1~
Preferably, the amount is 2.5 g/10 minutes. Examples of the copolymerization component include vinyl acetate, ethyl acrylate, methyl methacrylate, diethyl maleate, etc., and the proportion thereof is 10% by weight or less. The above-mentioned high-pressure low-density polyethylene is different from linear low-density polyethylene developed in recent years, and has a molecular structure having many long chain branches in the molecule. A long chain branch is one having a much larger number of carbon atoms than a short chain branch, which is about 2 to 6 carbon atoms. Comparing the physical properties of high-pressure low-density polyethylene with long chain branches and linear low-density polyethylene,
The difference is clearly revealed by the viscosity average molecular weight,
Taking the melt index of 2 as an example, high-pressure low density polyethylene having long chain branches has a value of 50,000 or less, and is about 30,000 to 40,000, and linear low density polyethylene has a value of about 70,000 to 80,000. The anti-slip agent 2 is composed of a blend of ethylene propylene rubber and high-pressure low density polyethylene having long chain branches as described above, and the blending ratio is 20 to 80% by weight of ethylene propylene rubber, preferably 30 to 70% by weight. % more preferably 40 to 60% by weight, high pressure low density polyethylene with long chain branching is 80 to 60% by weight
The content is 20% by weight, preferably 70-30% by weight, more preferably 60-40% by weight. Of course, the above-mentioned additives may be further added to this mixture. Furthermore, in addition to the above-mentioned ethylene propylene rubber and high-pressure low-density polyethylene having long chain branches, other thermoplastic synthetic resins may be added to these mixtures in an amount that does not exceed the amount of each of the above two components. good. As other thermoplastic synthetic resins, polyolefin resins are preferred. Furthermore, a part of the above ethylene propylene rubber may be mixed with ethylene propylene diene rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, polybutadiene rubber, polyisoprene rubber, within a range not exceeding the blended amount of ethylene propylene rubber.
Other synthetic rubbers such as polychloroprene rubber, polyurethane rubber, and thiol rubber may be used instead. The anti-slip material 2 is formed from the above-mentioned mixture into a desired shape such as a band, string, plate, block, etc. by extrusion molding, injection molding, or other suitable molding means. The anti-slip material 2 should have a hardness (hardness according to JIS K 6301) of JIS A75 to JIS A95 and a tensile strength {JIS
Strength by K6758-81 (at constant temperature of 20℃)} is 50
~250Kg/ ^cm2 is desirable. Heat welding is used to install the anti-slip material 2 on the molded product 1. For example, if the surface of the molded product 1 and the surface of the non-slip material 2 are melted using hot air or a hot plate, both of them are still molten. Crimp while in the state,
A method of joining the two, when molding the molded product 1 by injection molding etc., the anti-slip material 2 is placed at the required position in the mold.
is fixed, molten polypropylene is filled into the mold, and the heat of fusion is used to thermally weld the molded product 1 and the anti-slip material 2. , a method is used in which the material is extruded into a string shape or the like, and then pressed and welded to the surface of the molded product 1 (which may be preheated, oxidized, etc., to improve adhesion). Usually, a method is used in which a non-slip material 2 is placed near a molded product 1, and hot air is blown onto both to melt the surface of the molded product 1 and the surface of the non-slip material 2, and the two are crimped and welded. It will be done. The welding conditions for this welding method are the temperature of the hot air,
It varies depending on the amount of hot air, the distance from the hot air outlet to the molded product 1 and the anti-slip material 2, etc., and cannot be definitively determined, but if we take a line speed of about 1 m/mm as an example, it will be about 600 to 800°C. Hot air (temperature of the heater inside the hot air generator) of While the condition is still in place, remove the comrades from the molten part.
This is done by pressing with a pressure roller or the like at a pressure of about 0.5 kg/cm or more. Next, the characteristics of the molded article of the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Various physical properties described in the examples were measured by the following measurement methods. (1) Melt index: Measured at a constant temperature of 20°C in accordance with JIS K 6760-81. (2) Density: Same as above.(3) Tensile strength: Same as above.(4) Elongation: Same as above. Using a test piece, peel approximately half of the anti-slip material from the base material in the length direction, and then remove the peeled anti-slip material from the base material.
Fix the anti-slip material and one end of the base material to the chuck of the testing machine while folded 180 degrees, and peel the anti-slip material from the base material at a constant speed of 50 mm/min at a constant temperature of 20°C to measure the force required for peeling. was read and the average value was displayed in Kg/cm. (6) Sliding angle: 2mm thick, length and width on the surface plate
A 250 mm anti-slip material sheet was attached, and a sheet made of polyethylene or polypropylene with a thickness of 2 mm and a length and width of 80 mm was placed thereon, and a load of 1 kg was applied to the sheet. From this state, one side of the surface plate was pulled up at a constant speed of 100 mm/min, and the angle at which the placed sheet started to slide (angle with respect to the horizontal plane) was measured, and the average value of three measurements was calculated. (7) Hardness: 20℃ according to JIS K 6301-81A method
Measured under constant temperature. (8) Wear rate: Using a custom fabric abrasion tester manufactured by Daiei Kagaku Co., Ltd., No. 40 sandpaper was brought into contact with a non-slip material measuring 35 mm in length, 20 mm in width, and 2 mm in thickness.
A load of 3.4 kg (7.5 1b) was applied and the anti-slip material was worn back and forth at a constant temperature of 20°C with a stroke of 50 mm, repeated 5000 times, and the amount of wear was expressed as a weight percentage of the original weight of the anti-slip material. In the table of examples, ethylene propylene rubber is referred to as "EPM", ethylene homopolymer of high-pressure low density polyethylene with long chain branching is referred to as "HPLD", and ethylene-vinyl acetate copolymer is referred to as "EVA". It was abbreviated as. Examples 1-2 Ethylene propylene rubber (EPM) (manufactured by Japan EP Rubber Co., Ltd., ethylene propylene rubber
EPO2P, ethylene content 74% by weight) and high-pressure low-density polyethylene (ethylene homopolymer) (EPLD) with long chain branching, {manufactured by Mitsubishi Chemical Corporation, Novatek F100, Melt Index (190°C):
0.42 g/10 minutes, density: 0.92 g/cm ³ } in the ratio shown in Table 1 below, and extruder {Tanabe Plastic Machinery
Co., Ltd., VS30−22 type extruder, tip Dalmage type 30
φ, L/D: 22, compression ratio: 3.5} to make pellets, and then press molded to a thickness of 2 mm and length.
A 250mm sheet was made and used as an anti-slip material. Polypropylene {manufactured by Mitsubishi Yuka Co., Ltd., Mitsubishi Noblen BC-8, melt index (230℃): 1.2
g/10 minutes, density: 0.9 g/cm ³ } onto a plate with a thickness of 3.5 mm and a length and width of 250 mm, and the above anti-slip material sheet was placed at 230°C for 5 minutes at 4 kg/cm ² Heat welding was carried out by press molding under pressure conditions. Table 1 shows various physical properties of the obtained anti-slip agent. Examples 3 to 5 An anti-slip material was prepared in the same manner as in Example 1, except that HPLD was replaced with an ethylene-vinyl acetate copolymer (manufactured by Sumitomo Chemical Co., Ltd., Evatate D2011, vinyl acetate content 5% by weight). A heat-welded molded product was obtained. Table 1 shows various physical properties of the obtained anti-slip material. Comparative Examples 1 to 3 Ethylene propylene rubber or
Using HPLD, ethylene propylene rubber alone,
An anti-slip material made using HPLD alone or a mixture of ethylene propylene rubber and HPLD outside the scope of the present invention was treated in the same manner as in Example 1 to obtain a molded product with the anti-slip material thermally welded. Ta. Table 1 shows various physical properties of the obtained anti-slip material. Example 6 The pellets of Example 3 were made into a belt-shaped sheet with a thickness of 2 mm, width of 20 mm, and length of 1 m using an extruder, and the belt-shaped sheet was used as a non-slip material to make a pallet made of the same polypropylene as used in Example 3. A structure similar to that shown in FIG. 1 was heat welded to the surface. Thermal welding is performed by melting the anti-slip material and the surface of the pallet using hot air at a temperature of 700 to 800℃ (built-in heater temperature) and a flow rate of 120/min, and pressing both together with a pressing force (roller linear pressure) of 2 kg/cm. I did it. The anti-slip material adheres well to the pallet,
The anti-slip properties were also sufficient for practical use.

[Table] The polypropylene molded product to which the anti-slip material of the present invention is attached has good anti-slip properties between it and the articles placed on the pallet, for example, when this molded product is used as a pallet for transporting cargo. It also has excellent wear rate, welding strength, etc., and is very desirable in practical terms.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a pallet which is an example of the molded product of the present invention. In the figure, 1 indicates a molded product (pallet), and 2 indicates a non-slip material.

Claims (1)

[Claims] 1. Weight ratio of ethylene propylene rubber to high-pressure low density polyethylene having long chain branches of 20:80 to 20:80.
A non-slip polypropylene molded product made by heat-welding a non-slip material made from an 80:20 mixture to a polypropylene molded product. 2 Ethylene propylene rubber contains ethylene component.
The polypropylene molded article according to claim 1, which contains 60 to 80% by weight and 40 to 20% by weight of a propylene component. 3. The method according to claim 1 or 2, characterized in that an ethylene-vinyl acetate copolymer copolymerized with 10% by weight or less of vinyl acetate is used as the high-pressure low-density polyethylene having long chain branches. Polypropylene molded product.