JPS5913344B2 - Synthetic resin pallet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure of a synthetic resin pallet for the purpose of improving the rigidity, abrasion resistance, and impact resistance of a pallet having a product wall thickness of approximately 3 mm or more.

Chemically bonding an inorganic filler and a polyolefin is described, for example, in Japanese Patent Publication No. 5-40542 and No. 46-21.
No. 211, No. 47-7894, or Japanese Unexamined Patent Publication No. 1973-
67199 and JP-A-48-167339, etc., this is possible using conventionally well-known techniques, and these methods dramatically improve physical properties such as rigidity and impact resistance compared to simple blend systems. improve. By examining the fractured surface of these special inorganic filler-containing polyolefin compositions with an electron microscope, for example, as shown in FIG.
It is known that it has a completely different structure from that of the solid composition. The special inorganic filler-containing polyolefin composition referred to in this invention is a polyolefin composition containing an inorganic filler such as calcium carbonate, aluminum hydroxide, or magnesium hydroxide with an average particle size of 0.1 μ to 50 μ and polyethylene, polypropylene, or a copolymer thereof. It is defined as a composition consisting of a polyolefin, such as a combination, in which an electron micrograph of a fractured surface clearly shows that the inorganic filler and the polyolefin are bonded. In general, it is extremely difficult to satisfy both rigidity and impact resistance for synthetic resin pallets, considering the resin used. Improving rigidity reduces impact resistance, and improving impact resistance Therefore, for pallets etc., we first consider using resin with good impact resistance and abrasion resistance.
Currently, rigidity is compensated for by structures such as ribs, L-shapes, T-shapes, and U-shapes.

Looking at the synthetic resin pallets currently in use on the market, they are insufficient in terms of physical properties such as rigidity, impact resistance, and abrasion resistance that are originally required for pallets. There are 30 things that need to be improved.

Some products use insert molding to improve rigidity, but when it comes to large structures such as pallets, there are problems due to the difference in coefficient of expansion between resin and metal, or problems with workability when inserting. I don't like it at all. 35 It is also possible to use a synthetic resin that has all of these physical properties, but so far there is no suitable one from the viewpoint of price and functionality.

This invention uses a special inorganic filler-containing polyolefin composition with extremely excellent rigidity and impact resistance for the product core side, and a special structure that uses low-MI high-density polyethylene with a high molecular weight for the product skin side, making it possible to improve It was designed to solve all of the problems at once.

Moreover, in the structure of this invention, the product core layer 20 to 60
Similarly to this invention, rigidity can be improved by using a polyolefin composition in which % by weight of an inorganic filler is simply blended, in other words, by using a blended composition in which the inorganic filler and polyolefin are not chemically bonded. It is possible.

However, the structure of the product of the present invention has excellent impact resistance, and this is due to the polyolefin composition containing a special inorganic filler used in the core of the product. Even if the product skin side is coated with low-MI high-density polyethylene having good impact resistance, this performance cannot be achieved by the structure of the product of this invention. The structure of this invention has M on the product skin side.
By using high-density polyethylene with a low MI of 0.01 to 1.0, the abrasion resistance and impact resistance are improved, and the product core side contains a special inorganic filler of 20 to 60% by weight. By inserting a polyolefin composition containing an inorganic filler, the rigidity is improved and all of these physical properties of the current pallet are improved.

If the structure of this invention is used in a pallet, the rigidity will be improved, and the abrasion resistance and impact resistance will also be improved, and the polyolefin composition containing a special inorganic filler to be inserted into the product core side can be recycled. In terms of price, it can be molded at a low cost.

In addition, in terms of incineration, the polyolefin composition containing a special inorganic filler inserted into the product core side is a synthetic resin that is easier to incinerate than polyolefin alone.
It is also very advantageous in terms of waste pollution, which is currently a problem. By the way, a pallet into which a special inorganic filler-containing polyolefin composition containing less than 20% by weight of an inorganic filler is inserted has insufficient rigidity, and the effects of the present invention cannot be obtained.

Furthermore, attempts were made to form pallets by inserting a special inorganic filler-containing polyolefin composition containing more than 60% by weight of inorganic fillers, but the fluidity was poor and a satisfactory pallet product could not be obtained. . In addition, for pallets that place importance on surface smoothness, the product skin side is made of low-MI high-density polyethylene with a substance that has an anti-slip effect, such as rubber, or is attached to it to prevent the cargo from slipping. It can also be ζ-.

Alternatively, the weight can be reduced by foaming the polyolefin composition containing a special inorganic filler, which is inserted into the product core, by 1.2 to 2.0 times using a chemical or physical foaming agent. It is.

Hereinafter, specific examples will be described. The test sample shown in Figure 2 uses a Toshiba 1S-1250AN injection molding machine, and is based on Japanese Patent Application Laid-open No. 50-8854 or No. 50-74.
The pallet is formed by injection molding one side at a time using the Sanderch molding method found in No. 660, etc., and welding the legs on both sides. Example 1 500 x 500 x 10 having the structure as shown in Figure 2
0m7! In the L palette, MI = 1.0 for skin layer 1
A high-density polyethylene with a low MI of 0.965 (manufactured by Asahi Kasei Corporation; Santech A-260) was formed, and the core layer 2 was made of a polyolefin composition containing a special inorganic filler (manufactured by Asahi Kasei Corporation;
One has a sandwich structure in which a calcium carbonate concentration of 48 (I) calculated from the incineration ash residue is inserted, and the skin layer 1 and core layer 2 are both MI
= 1.0, the maximum strain with a single product of low MI high-density polyethylene (manufactured by Asahi Kasei Corporation; Santec A-260) with a density of 0.965 was determined by applying a uniformly distributed load of 500k9, supported at two points (1 with a span of 420m0) When measured and compared after several months, it was found that
It looked like [A] in the table.

Example 2 Skin layer 1 was prepared using a pallet with the same shape and dimensions as Example 1.
The maximum amount of strain is obtained by forming a low-MI high-density polyethylene (manufactured by Asahi Kasei Corporation; Santec B-180) with MI = 0.04 and density 0.955, and having a sandwich structure in which Loima-Sl32O is inserted in the core layer 2. were measured and compared under the same conditions as in Example 1, and the results were as shown in [B] in Table 1.

Example 3 With a pallet of the same shape and size as Example 1,
Skin layer 1 is made of low-MI high-density polyethylene with an MI of 0.3 and a density of 0.960 (manufactured by Asahi Kasei Corporation: Suntech B-17).
0), and the core layer 2 has a sanderch structure in which Loima-Sl32O is foamed 1.5 times using a chemical foaming agent. The maximum strain amount was measured under the same conditions as in Example 1 and compared. The result was as shown in [C] in Table 1.

Example 4 Skin layer 1 was prepared using a pallet with the same shape and dimensions as Example 1.
The largest of the sanderch structure in which Santec A-260 is formed and a core layer of 2VC special inorganic filler-containing polyolefin composition (manufactured by Asahi Kasei Co., Ltd.: Roima-1 Sl42O, calcium carbonate concentration 59% calculated from incineration ash residue) is inserted. When the amount of distortion was measured and compared under the same conditions as in Example 1, the results were as shown in Table 1 [D].

Example 5 A 400 x 400 x 3 mm flat plate (skin layer 0.5 mm, core layer 2 m0) was injection molded using the same molding method as the sandwich molding method used to mold the pallet in Example 1, and a single product of Santec A-260 was made. and skin layer 1K suntech A-2
60, Loima-Sl32O was formed on the core layer 2, Santech B-180 was formed on the skin layer 1, Loima-Sl32Ol was formed on the core layer 2, and Santech B-1 was formed on the skin layer 1.
A test plate with a sanderch structure of Santech J-240, in which 50% by weight of calcium carbonate was simply blended into the core layer 2, was tested with a weight diameter of 10R, a weight load of 3kg, and a falling weight height of 90s. A falling weight is applied under different conditions, and the number of falling weights until breakage (cracking) is measured and the amount of deformation (maximum deformation from the reference surface before falling weight) is measured and compared when the weight is dropped once and five times. The result was as shown in Table 2.

Example 6 A bending test piece was cut out from the pallet molded in Example 1, and a single piece of Santech A-260 was formed, Santech A-260 was formed on the skin layer 1, and Loima-Sl was formed on the core layer 2.
The bending rigidities of each of Sanderch structure B1 in which 32O was inserted and Sanderch structure C in which Sanderch B-180 was formed in the skin layer 1 and Loima-Sl32O was inserted in the core layer 2 were measured and compared. It became like B and C.

By using the structure of this invention in pallets5, compared to conventional high-density polyethylene single-piece pallets, the flexural modulus is twice as high in terms of rigidity, and the yield strength is 1 times higher.
．． The improvement was four times greater, and the amount of distortion was reduced to 1/2 to 1/3.

In terms of impact resistance, the product skin layer has an MI of 0.01~
forming a high density polyethylene with a low MI of 1.0;
Product Core Layer K By inserting the special inorganic filler-containing polyolefin composition referred to in this invention, impact resistance values that are approximately the same as those of a single high-density polyethylene product with good impact resistance and low MI can be obtained. I was able to do that.

[Brief explanation of the drawing]

Figure 1 shows the fractured surface of a polyolefin composition containing an inorganic filler magnified 3000 times by an electron microscope, where A is the special inorganic filler-containing polyolefin composition according to the present invention, and B is a simple blend. A photograph of the composition is shown, and FIG. 2 is a cross-sectional view of a pallet used in an example of the present invention. Figure 3 shows a comparison of bending stiffness. A is Santech A-2
60 single product, B has Santec A-260 inserted in the skin layer and LOIMA-Sl32O in the core layer, C has SanTEC B-1801 in the skin layer and LOIMA-Sl3 in the core layer.
Shown with 2O inserted. 1...Skin layer,
2...Core layer.

Claims (1)

[Claims] 1. A special inorganic filler-blended polyolefin composition characterized in that the inorganic filler and polyolefin are combined by kneading 20 to 60 weight percent of an inorganic filler and polyolefin to the product core side. insert,
The product skin side has a low MI (melt index measured at 190℃-2.16kg) of 0.01 to 1.0.
A synthetic resin pallet characterized by being wrapped with high-density polyethylene.