KR0138489B1 - Plastic composition for wood replacement - Google Patents

Abstract

The present invention relates to a plastic sheet or board composition for replacing wood, comprising 30 to 90 parts by weight of a polymer selected from polypropylene or polyethylene, 1 to 40 parts by weight of inorganic material, and 1 to 30 parts by weight of synthetic rubber.

Description

Plastic composition for wood replacement

The present invention relates to a composition for plastic sheets or boards for replacing wood. More particularly, it relates to plastic compositions that can be substituted for wood, plywood, and the like used in construction, civil engineering, and the like. Among them, synthetic resins such as polyolefin may be used as a raw material that can be manufactured from a composite plastic foam board or sheet having various specific gravity and physical properties depending on the application through a foam molding process; Synthetic rubbers such as butyl rubber and EPM EPD; And inorganic materials such as glass fibers, talc, asbestos, and the like, and have a specific gravity of 0.68 to 0.92.

Wood, which has been used for a long time in the construction and civil engineering fields, has been used for a long time because of its low specific gravity, easy processing, high bending strength and compressive strength, and relatively low cost, and its substitute material has not been considered. However, due to the high absorption rate of wood, the limitation of reuse, the impact of global environmental protection, the problem of the difficulty of purchasing wood, the sharp increase of the cost, and the depletion of material wood in the near future will be raised. Therefore, the development of his substitutes is very urgent. However, in order to maintain the mechanical strength that can be substituted for wood, it is necessary to use an engineering plastic system instead of a general-purpose resin, which is practically expensive because it is very expensive. In addition, since the specific gravity of plastic is higher than that of wood, processing difficulties in reducing the specific gravity through the foaming process also arise when plastic is used, and the development of plastic substitutes for wood for materials requires the price, foamability, mechanical strength and other factors of the basic materials. Various factors such as physical properties have been compounded so far, there have been many limitations.

Under these circumstances, the present inventors use a general-purpose resin as a basic material for wood substitutes for materials, but improve the mechanical properties by modifying the resin itself or adding synthetic rubber and various fillers according to the purpose of the final product. The present inventors have found that the above problems can be solved by appropriately adjusting the degree of modification of the resin and the content of the filler to suit the foaming suitability and the intended use of the product.

Hereinafter, the present invention will be described in detail.

The general-purpose resin used in the present invention is polyolefin, among which polypropylene and polyethylene are preferred, wherein polyethylene means high density polyethylene and / or low density polyethylene, and each content is 30 to 90% by weight of polypropylene and high density polyethylene. 10 to 50 weight percent and / or 10 to 50 weight percent low density polyethylene. Here, the high density polyethylene and the low density polyethylene can use only 1 type, or can use it in combination of 2 types.

In general, the higher the blending amount of polyethylene in the composition, the lower the heat resistance, the lower the flexural and compressive strength and the dimensional stability, while the foaming and impact strength are improved, and the higher the blending amount of polypropylene, the lower the foaming and impact strength and cold resistance. The flexural and compressive strength and the dimensional stability are good, so the combination ratio should be selected appropriately. It is also desirable to blend modified polypropylenes and polyethylenes or to modify them in the use of the compositions for applications where greater mechanical strength is required, and such modifications can be various. The resin blended in the composition of the present invention may be modified not only with the homo resin but also with the modified resin, with modification of the resin, or with use. As a method for modifying polypropylene, a method of adding a nucleophile to increase the crystallization rate of the resin and to increase the degree of crystallinity may be used. Generally, nucleating agents used in polypropylene include sorbitol type and metal salt type, and only one of them may be used or a combination thereof may be used. Specific examples thereof include potassium benzoate, lithium benzoate, sodium benzoate, sodium salt of methylenebis (2,4-di-tet-butylphenol) acid phosphate, aluminum bis (ｐ-ｔｅｒｔ-butylbezoate) hydroxy, 1,3,2,4-dibenzylidene sorbitol, bis (i-ethylbenzylidene) sorbitol, sorbitol-benzaldehyde and the like, and the amount thereof is preferably 0.001 to 0.8% by weight relative to the amount of polypropylene to be blended. Preferably it is 0.005-0.7 weight%.

It is preferable that the polypropylene used for this invention is MI0.5-10g / 10min, Especially preferably, it is 3-8g / 10min. If MII is too low, extrusion processing will be difficult. If MII is too high, the melting point will be too low, foaming will not be performed properly, and workability of a sheet | seat or a board will be inferior.

The polyethylene used in the present invention includes both low density and high density, and the lower the density, the better the foaming efficiency but the lower the mechanical rigidity, so the appropriate density range is 0.905 to 0.970 g / cm², preferably 0.910 to 0.965 g / cm ³. In addition, a suitable MI range is 0.01-5 g / 10 min, but the higher the MI, the lower the foaming efficiency and impact strength, but the compatibility and workability with polypropylene are improved, so the preferred range is 0.1-3 g / 10 min. Also in this case, homopolymer may be used or modified polymer may be used depending on the purpose of the final product. The modified polyethylene used in the present invention may cause crosslinking reaction between molecules by using special additives, resulting in flexural strength, flexural elasticity, tensile strength and It is to improve heat resistance. As a method of crosslinking polyethylene, the electron beam irradiation, the peroxide addition, the silane compound addition, and the method of adding a polyfunctional acrylate type compound were used. As the peroxide, benzoyl peroxide, docuyl peroxide, 1,3-bis (ｔ-butylperoxy-isopropyl) benzene may be used, and as the polyfunctional acrylate compound, 1,4-butadiol diacrylate , Epoxy acrylate, dipentaerythritol monohydroxy acrylate, trimethanol propane triacrylate, pentaerytriacrylate, triaryl isocyanurate and the like, and the amount of these peroxides is 0.001 to 0.6% by weight, 0.0001 ~ 1% by weight of acrylate compound, if the content of crosslinking additive is too high, the mechanical strength and foaming efficiency are increased, but the drawability between molecules is inferior and phase separation from polypropylene during the second processing is severe. If the content of the additive is too small, the reforming effect is reduced, so the preferred content is 0.001 to 0.5% by weight of peroxide, arc Acrylate based 0.001~0.8% by weight of a peroxide and an acrylate-based compound may be used in each of these it may be used separately and in combination.

The raw material used in the present invention is formed into a final product through the foam extrusion process with the addition of a blowing agent, wherein synthetic rubber may be added to increase the efficiency of foaming. In addition, since the impact strength of the product is significantly increased when synthetic rubber is added, it is suitable for a product where cold resistance is particularly required. Such synthetic rubbers include butyl rubber, isoprene rubber, isobutyl rubber, EP, EPM, etc., but if too much is added, the mechanical rigidity of the product is lowered. Therefore, the appropriate blending amount is 1 to 30% by weight, preferably 2 to 25% by weight. to be.

In addition, in the present invention, fillers are used to increase mechanical rigidity in addition to homopolymers and modified polymers. Suitable fillers are glass fiber, talc, asbestos, ceramic powder, metal oxide, calcium carbonate and the like. These fillers improve the flexural modulus and mechanical strength of the material, but when added too much, the foaming efficiency and the impact strength of the product are lowered, so the appropriate content is 1 to 60% by weight, preferably 3 to 50% by weight.

The content of the filler should be carefully selected according to the type of polymer, the type of processing machine and the properties of the final product. In the present invention, in consideration of the above matters, the base material is subdivided according to the properties and uses of the final product. First, the compound of homopolymer only, second, the compound of modified polymer only, third, homo or modified polymer and synthetic rubber and filler Divided into three types of liver compounds, the grade can be varied according to the performance, price, and use of the final product.

Hereinafter, the present invention will be described in detail with reference to Examples. The embodiment of the present invention is an example of a plastic foam board for plywood replacement in wood, it is clear by the gasket of the present invention that can also be used for the use of wood and the scope of the present invention is not limited to these embodiments.

In addition, only a few examples of the various nucleating agents, peroxides, polyfunctional acrylate-based compounds, synthetic rubbers, and fillers described above are examples, and all examples of the above-described types are equivalents, and thus, embodiments thereof will be omitted.

[Examples 1-3]

0.5% by weight of bis (i-ethylbenzylidene) sorbitol as a nucleating agent was added to the polypropylene powder, and then extruded into modified polypropylene (MI 7) and high-density polyethylene powder (MI 3) as a peroxide. Modified polyethylene (MI 0.08), cross-linked by addition of 0.08% by weight of 3-bis (tet-butylperoxy-isopropyl) benzene and 0.5% by weight of trimethylolpropanetriacrylate as a polyfunctional acrylate compound, was 100/0. The twin screw extruder (40 After compounding at, L / D28, the respective MI (230 ° C.) and the injection physical properties were analyzed. In addition, after mixing the compounded pellet with 0.9% by weight of the organic blowing agent (D-1500), the single screw extruder (50 , L / D300] was prepared in the foam board using T-DIE, and then shown in Table 1 by analyzing specific gravity and various physical properties. Various items in Table 1 were analyzed by the method shown in the following # 1.

#One

EXAMPLES 4-8

To the modified polypropylene and modified polyethylene 80/20 weight ratios of Examples 1 to 3, 10 weight ratios of talc, 20 weight ratios, 30 weight ratios, and 10 weight ratios of glass fiber and 20 weight ratios were added, respectively, Physical property analysis is shown in Table 1.

[Examples 9 to 10]

Compounding and physical property analysis were carried out in the same manner as in Examples 1 to 3 by adding 10 parts by weight and 20 parts by weight of EPM (EJON, JTSAOLON 503) to the modified polypropylene, modified polyethylene, and talc 80/20/20 weight ratio of Example 5. It carried out and is shown in Table 1.

Comparative Example 1

The physical properties of the plywood having a thickness of 12 t are measured in the same manner as in Examples 1 to 3 and shown in Table 1.

TABLE 1

In general, the most excellent property of plywood is the flexural strength. As shown in Table 1, the product can be obtained better than the flexural properties of plywood by modifying PP and PE or by adding fillers. Possible good results are shown.

Comparative Example 2-4

Polypropylene (Korean emulsification 4107, MI 7) and high-density polyethylene (Korean emulsification E30M MI0.05, Decnylxxxy 70) were mixed at 100/0 weight ratio, 80/20 weight ratio, and 60/40 weight ratio, respectively, Examples 1 to 3 Compounding and physical property analysis were performed in the same way as shown in Table 2 below.

[Comparative Examples 5-6]

It is the same as that of the comparative examples 2-4 except having used the low density polyethylene (Hanyang Chemical 5302, MI0.3, December 210.2) instead of the high density polyethylene.

[Comparative Examples 7-9]

Compounding and physical property analysis were performed in the same manner as in Examples 1 to 3 by mixing talc in 10 weight ratios, 20 weight ratios, and 30 weight ratios, respectively, in the polypropylene and high density polyethylene 80/20 weight ratio of Comparative Example 2.

TABLE 2

As shown in Table 2, when only the homopolymer is used, the physical properties of the base material and the foam board are greatly reduced, but the addition of the filler significantly improves the physical properties. In this case, it can be used as a substitute for lower plywood where such a large mechanical strength is not required.

[Examples 11 to 13]

The base material of Comparative Example 2, Example 2, and Example 5 was produced in the board | substrate of thickness 17t by the method similar to Examples 1-3, and the bending load was shown in Table 3 compared with the board of thickness 12t.

TABLE 3

As shown in Table 3, even if the thickness of the board is only slightly thick, the flexural load is greatly increased, so that the use of the final product requires very high mechanical strength over the plywood by supplementing some dimensions or increasing the degree of modification of the base material (eg It can be applied sufficiently to solid wood.

[Examples 14-15]

After dipping the plywood 12 t of the comparative example 1 of the foam board 12 t of Example 12 in distilled water for 24 hours, the sample which absorbed water was completely dried, and the bending strength was measured by the same method as Example 1-3. 4 is shown.

[Table 4] After absorption (before absorption)

As shown in Table 4, the flexural strength after water absorption of plywood is about 28% lower than that of the original product, so the continuous use of the product (the more you use it, the more water will be absorbed by the snow, air, etc.). It can show more excellent bending characteristics.

Claims (11)

A composition for wood replacement plastic sheets or boards comprising 30 to 90 parts by weight of a polymer selected from polypropylene or polyethylene, 1 to 40 parts by weight of inorganic matter, and 1 to 30 parts by weight of synthetic rubber, and whose specific gravity is 0.68 to 0.92. The composition of claim 1, wherein the polymer is at least one member selected from the group consisting of homo polypropylene or modified polypropylene, homo polyethylene or modified polyethylene. The composition of claim 2 wherein the polyethylene is a high density or low density polyethylene. The composition of claim 1 wherein the mineral is selected from the group consisting of talc, fiberglass, asbestos, ceramic powder. The composition according to claim 1, wherein the synthetic rubber is at least one selected from EP, EPD, butyl rubber, isoprene and isobutyl rubber. 3. The composition of claim 2 wherein the modified polypropylene is modified by adding a nucleating agent. The composition according to claim 2, wherein the modified polyethylene is modified by crosslinking. 7. The composition of claim 6, wherein the nucleophile is selected from sorbitol or metal salt form. The composition of claim 2, wherein the homopolypropylene is propylene-alphaolekin random or block copolymer. Single layer foam board or multi-layer foam board having a specific gravity of 0.68 to 0.92 made of the wood substitute plastic composition of claim 1 The composition of claim 5 wherein the mineral is in the form of a powder, yarn, strand, cloth, foaming, pellets, mat.