JP3422455B2 - Woody thermoplastic resin composition and filler for the composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition having a woody texture, and can be used not only as a sill, a handrail, and other various building materials, but also in a wide range of materials such as daily commodities, stationery materials, and formwork materials. The present invention relates to a resin composition that can be employed, and a silicone-treated cellulose-based filler for the resin composition.

[0002]

[Prior art and its problems to be solved] Wood has excellent strength,
It is lightweight and easy to handle, and because it has textures, such as visual and tactile sensations that synthetic resins do not have, it has been widely used in construction materials by taking advantage of these characteristics, but in recent years it has been polluted or destroyed in the natural environment. From the standpoint of preventing forests and protecting forests, there is an urgent need to switch to artificial wood (called molded wood) that replaces natural wood.

As the synthetic resin used for the above-mentioned molded wood, polyolefin is used from the viewpoints that it is difficult to generate harmful gas when the molded product burns, is easy to recycle, and has excellent mechanical and thermal characteristics. (In particular, polypropylene) is suitable, and examples of the use thereof include organic or inorganic foaming agents, calcium carbonate, inorganic fillers such as talc,
It is known to mix cellulosic fillers such as wood powder and rice husk, and heat-melt and form the mixture (for example, JP-A-53-9835).
1, JP-A-58-91745).

However, when a cellulosic filler is simply used, the bond between different phases of the hydrophobic polypropylene and the hydrophilic cellulosic filler is insufficient, and the impact strength is lowered. In addition, since the cellulosic filler is organic, it is mixed with polypropylene and plasticized and molded in a fluidized state (170 ° C to 210 ° C).
At (° C.), there is a problem that coloring (blackening) due to deterioration due to heat and eventually thermal decomposition occur.

It is also known to modify polyolefins with silicone (for example, JP-A-57-192446). However, this is different from modifying the cellulosic filler as in the present invention to suppress deterioration and coloring due to heat.

The present invention solves the disadvantages such as coloring of the cellulosic filler and the reduction of mechanical strength in the molded articles of the prior arts, the molded wood can be produced at low cost by an easy means, and it is advantageous for industrial implementation. The present invention provides a wood-based thermoplastic resin composition.

When a pyrolyzable organic foaming agent is used alone as a foaming agent, the foam structure of the foamed molded product is fine, but the molding shrinkage tends to be large. When the agent is used alone, the molding shrinkage is small, but the bubbles tend to be coarse and the mechanical strength tends to be lowered.

The present invention further provides a wood-based thermoplastic resin composition which solves the problems caused by the above-mentioned foaming agent, such as shrinkage or coarse foaming during molding, deterioration of mechanical strength and the like.

[0009]

The present invention provides a wood-based thermoplastic resin composition containing a polyolefin, a cellulosic filler, a modifier, an inorganic filler and a foaming agent,
A wood-based thermoplastic resin composition in which a cellulosic filler is modified with silicone, and a pyrolyzable organic and inorganic foaming agent as a foaming agent are used in combination. Organic: Inorganic foaming agent introduced weight Ratio of 5:95 to 50:
The wood-based thermoplastic resin composition, which is 50, and further, in wt%, the following component compositions: polyolefin 25 to 85, silicone-treated cellulose 5 to 51, modifier 2 to 15, inorganic filler 5 to 30, the above-mentioned wood-based thermoplastic resin composition comprising 0.1 to 2 of a foaming agent, silicone-treated cellulose is used to infiltrate the cellulose with alcohol, and then a compatible resin with polyolefin, and then a siloxane polymer is added and reacted. And a filler for the above-mentioned wood-based thermoplastic resin composition.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Polyolefins used in the present invention include polyethylene, polypropylene, ethylene-propylene copolymers, ethylene-butene copolymers, ethylene-pentene copolymers and the like, with polypropylene being preferred, A case of polypropylene alone, a copolymer of propylene-ethylene or the like, or a mixed system thereof is also included.

The content of polypropylene in the resin composition is
The range of 25-85 wt% is preferred. If it is less than the above range, the amount of the resin component tends to be too small, and it tends to be difficult to perform heat melting and foam molding. On the other hand, when the amount exceeds the above range, it is difficult to improve the mechanical strength of the molded product and it is difficult to improve the texture.

The cellulosic filler in the present invention is
It is possible to use various kinds of wood constituting cellulose, bamboo, kenaf (a hibiscus plant of the mallow family), crushed materials such as rice husks, and the like, or a mixture thereof.

The filler size is preferably in the range of 100 to 325 μm, and when it is 100 μm or less, the aspect ratio is small and the entanglement with polypropylene is weak and the mechanical strength is not sufficiently improved. On the other hand, if it exceeds 325 μm, the mixing and dispersion with polypropylene is insufficient and the cellulosic filler tends to agglomerate, resulting in poor moldability.

The silicone for treating the cellulosic filler used in the present invention is a siloxane polymer or a copolymer with another polymer, a metallosiloxane polymer or a copolymer with another polymer, a vinylsilane polymer or another polymer. It is possible to employ a copolymer with or a mixed system thereof. These may be appropriately selected in consideration of compatibility with polypropylene.

To treat the cellulosic filler with silicone, for example, 100 parts by weight of the cellulosic filler (wood flour, rice husk, etc.) in 0.1 to 2 parts by weight of alcohol in a high-speed rotary shear mixer (a super mixer as an example). (For example, 0.5 parts by weight of polyvinyl alcohol) is added and the temperature is raised to 80 ° C with sufficient mixing to infiltrate the cellulose-based filler, and then urea-based and melamine-based compatible with polypropylene based on 100 parts by weight of the cellulose-based filler. , 0.1 to 1 part by weight of another polymer (for example, 0.2 part by weight of a heat-softened epoxy polymer) is added and mixed, and 1 to 5 parts by weight (eg, 2 parts by weight) of a siloxane polymer with respect to 100 parts by weight of a cellulosic filler. In addition, while thoroughly mixing, raise the temperature to around 120 ° C, and further cool to around 50 ° C, It can be obtained over emissions treated cellulosic filler.

The amount of the silicone-treated cellulosic filler introduced into the resin composition is preferably in the range of 5 to 51 wt%. If it is less than 5 wt%, the mechanical strength is not sufficiently improved, and it is difficult to obtain a woody texture. 51 wt%
If it exceeds, the polypropylene content becomes relatively small, and it tends to be difficult to fluidize by heating and foam molding.

The modifier is effective in increasing the viscosity of the resin composition at the time of foam molding to form fine and uniform foam cells, and also prevents the molded article from deforming during cooling. In particular, acrylic modifiers are recommended. As the modifier, an acrylic acid ester polymer, a copolymer of an acrylic acid ester and another polymer, a methacrylic acid ester, a copolymer of a methacrylic acid ester and another polymer, or a mixed system thereof is used. preferable. These modifiers may be appropriately selected in consideration of compatibility with polypropylene.

The amount of the modifier such as an acrylic modifier introduced into the resin composition is preferably in the range of 2 to 15 wt%. 2 wt%
If it is less than the viscosity of the resin composition during foam molding is too low,
The cell coating is easily destroyed by the gas pressure during foaming. 15wt
If it exceeds 0.1%, the viscosity of the resin composition at the time of foaming is too high, the foaming efficiency is lowered, and the flexibility of the molded product tends to be reduced to make it brittle, and it is difficult to improve the mechanical strength.

As the foaming agent, a pyrolytic organic and / or inorganic foaming agent is used. Examples of thermally decomposable organic blowing agents include azo compounds such as azodicarbonamide or azoisobutyronitrile, nitroso compounds such as N-N'-dinitrosopentamethylenetetramine, and sulfonylhydrazide compounds such as P-toluenesulfonylhydrazide. Etc. that mainly generate nitrogen gas, and as the thermal decomposition type inorganic foaming agent, those that mainly generate carbon dioxide gas such as sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, etc. are preferably used. It is preferable to use one or more agents in combination with one or more inorganic foaming agents.

When the above pyrolyzable organic foaming agent is used alone, the foaming agent generates nitrogen gas which is difficult to diffuse and aggregate in the resin to form fine cells. Therefore, the shrinkage during cooling becomes large.
Further, when an inorganic foaming agent is used alone, the foaming agent generates carbon dioxide gas which easily aggregates in the resin, so that the cells tend to become coarse and the mechanical strength of the molded article tends to decrease, but it is an endothermic decomposition type. Has a characteristic that the temperature is lowered and the shrinkage during cooling is small.

In a preferred embodiment of the present invention, the above organic and inorganic blowing agents are used in combination, the former:
By setting the mixing weight ratio of the latter to 5:95 to 50:50, bubbles do not become coarse and molding shrinkage can be minimized. When the ratio of the organic foaming agent exceeds 50, molding shrinkage is large and not practically preferable, and when it is less than 5, the inorganic foaming agent becomes excessive and the cell structure becomes coarse, so that the strength tends to be lowered.

The amount of the foaming agent introduced into the resin composition is
The range of 0.1 to 2 wt% is preferable. If it is less than 0.1 wt%, the expansion ratio does not increase, and even if it exceeds 2 wt%, the expansion ratio does not increase due to excessive gas release. Destruction and coloring due to residual foaming agent are likely to occur.
In addition to the above-mentioned foaming agent, it is possible to contain a foam regulator, a foaming decomposition temperature regulator, and the like.

As the inorganic filler which acts as a nucleating agent during foaming and improves the hardness and scratch resistance of the molded article,
Oxides (silica, alumina, etc.), hydroxides (aluminum hydroxide, magnesium hydroxide, etc.), carbonates (calcium carbonate, magnesium carbonate, etc.), sulfates (calcium sulfate, barium sulfate, etc.), silicates (talc, There are various types such as feldspar) and nitrides (boron nitride, silicon nitride, etc.), but calcium carbonate is preferable because it is inexpensive, easily available, has few impurities, and has a small amount of adsorbed water.

The amount of the inorganic filler, such as calcium carbonate, introduced into the resin composition is preferably about 5 to 30% by weight, and when it is less than 5% by weight, it acts as a nucleating agent during foaming and increases the resistance of the molded product. Insufficient scratchability, 30wt%
If it exceeds, it is difficult to expect sufficient improvement in mechanical strength such as impact resistance.

Further, the wood-based thermoplastic resin composition may be a known stabilizer, lubricant, flame retardant, antistatic agent, antioxidant, ultraviolet absorber, antibacterial / antifungal agent, colorant, etc., if necessary. Can be appropriately contained.

In the present invention, first, the resin composition is
Mix by heating at ~ 190 ° C and pelletize by extrusion molding or other appropriate granulation means. At this point, a uniform and dense pellet is obtained, but if the cellulose is not treated with silicone,
It turns black (dark brown). Add 1 of the above pellets
It is heated and fluidized at 70 to 210 ° C., foamed, and obtained by a means such as extrusion molding and cast molding to obtain a molded product having a predetermined shape, and cooled to obtain a molded product. It should be noted that the blackening becomes more remarkable in the cellulose not subjected to the silicone modification treatment, but the modification-treated cellulose of the present invention can prevent this.

[0027]

EXAMPLES Specific examples will be described below in comparison with comparative examples.

[ Example 1 (1-1-1-9)] Polypropylene (manufactured by Grand Polymer Co., Ltd., trade name B-101), silicone-treated wood powder obtained by the following treatment method, and methacrylic acid The ester polymer and calcium carbonate were mixed in a desired weight ratio, and the mixed raw materials were put in a super mixer, kneaded and uniformly dispersed to raise the temperature to 110 ° C., and after removing volatile components, azodicarbonamide, Add the desired amount of sodium hydrogen carbonate, mix thoroughly, and remove. 160 ℃ -190 ℃
A wood-based thermoplastic resin composition was obtained by granulating (pelletizing) with a single-screw extruder set to. The weight percentage of the resin composition is shown in Table 1.

In order to obtain the silicon-treated wood powder, 0.5 parts by weight of polyvinyl alcohol was added to 100 parts by weight of the wood powder in a super mixer, and the temperature was raised to 80 ° C. with sufficient mixing to allow the wood powder to infiltrate. After that, 0.2 parts by weight of epoxy polymer preheated to 80 ° C was added to 100 parts by weight of wood flour and mixed, and then 2 parts by weight of siloxane polymer was added to 100 parts by weight of wood flour and heated to 120 ° C while mixing. Let
Further cooling to 50 ° C. gives a siliconized wood flour.

The wood-based thermoplastic resin composition thus obtained was introduced into a single-screw extruder and extrusion-molded under the following molding conditions. The density of the obtained molded product was measured, and the non-shrinkability was visually inspected (Ranking: Almost no shrinkage-- ○, Shrinkage--X), and the non-coloring property from the appearance (Ranking: No coloring-- ○, colored-- ×), texture (ranked by visual and tactile sensations: those that are recognized as woody-- ○, those that are difficult to recognize as woody--x) were examined.

Further, the molded product was cut into a predetermined size and cut into a sample for measuring each physical property. For each manufactured sample, the physical properties of tensile yield strength, tensile elongation at break (above JIS K 7113), bending strength, elastic modulus (above JIS K 7203), and Charpy impact strength (according to JIS K 7111) were measured. . The results are shown in Table 1.

Extrusion molding condition Model Single screw extruder (made by Ikegai Co., Ltd., caliber 40mm) Screw L (screw length) / D (outer diameter) 22〃 CR (compression ratio) 3.5 Temperature Cylinder 1 170 ℃ Cylinder 2 200 ℃ Cylinder 3 210 ℃ Adapter 190 ℃ Die 180-190 ℃ Molded product shape 30 (w) × 4 (T) mm

[Comparative Example 1 (1-1 to 1-4)] A mixture having a compounding ratio outside the range of the present invention, or one not having been treated with wood flour was prepared in the same manner as in the above Example, and Molded by means to obtain a molded product, various tests were conducted in the same manner. Table 2 shows the weight percentage of the resin composition and the results of various tests.

[ Example 2 ( 2-1 to 2-9 )] Instead of the wood flour of Example 1, chaff that had been sieved and sized to a size in the range of 100 μm to 325 μm was used. Otherwise, it was prepared in exactly the same manner as in Example 1, molded by the same means to obtain a molded product, and various tests were conducted in the same manner. Table 3 shows the weight percentage of the resin composition and the results of various tests.

[Comparative Example 2 ( 2-1 to 2-4 )] Instead of the wood powder of Comparative Example 1, a chaff obtained by sieving and sizing in a size range of 100 μm to 325 μm was used. Other than that was prepared exactly as in Comparative Example 1, molded by the same means to obtain a molded product, and various tests were similarly carried out. Table 4 shows the weight percentage of the resin composition and the results of various tests.

[0036]

[Results] The wood-based thermoplastic resin composition of this example is caused by the heat-induced deterioration due to the silicone-denaturing treatment of cellulose even when exposed to the melt molding conditions of high temperature (170 ° C to 210 ° C). It does not cause coloration, has almost no shrinkage during molding, and is very similar in texture to wooden products. Further, it is possible to obtain a molded product which is excellent in mechanical strength, heat resistance and the like, and which is highly practical and economical. On the other hand, in the comparative example, the cellulose is colored or shrinkage is observed at the time of molding, or the woody texture is different from wood products, and the mechanical strength is also poor.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

[0041]

The wood-based thermoplastic resin composition of the present invention is
Even when exposed to high temperature (170 ℃ ~ 210 ℃) melt molding conditions,
Since the cellulose is modified with silicone, coloring due to deterioration due to its heat does not occur, there is almost no shrinkage during molding, and the texture is very similar to wood products. Furthermore, it is possible to obtain a molded product that is excellent in mechanical strength, heat resistance, and the like, and is highly practical and economical. Therefore, it is difficult to adopt a conventional construction material for a house, such as a sill, a handrail, a door, a rim, a face edge. , Window frames or stationery materials,
The effect is that it can be widely used for daily necessities, formwork materials and the like.

Continuation of the front page (56) Reference JP 62-267344 (JP, A) JP 3-269036 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08J 9 / 04 C08L 1/00-1/08 C08L 23/00-23/02 C08L 97/02

Claims (4)

(57) [Claims] 1. A polyolefin, a cellulosic filler,
A wood-based thermoplastic resin composition comprising a modifier, an inorganic filler and a foaming agent, wherein the cellulose-based filler is modified with silicone. 2. A thermal decomposition type organic and inorganic foaming agent is used in combination as a foaming agent, and the introduction weight ratio of organic: inorganic foaming agent is 5:95 to 50:50. The wood-based thermoplastic resin composition according to claim 1. 3. The wood-based thermoplastic resin composition according to claim 1 or 2, characterized in that the composition has the following composition by weight. Polyolefin 25 to 85, silicone-treated cellulose 5 to 51, modifier 2 to 15, inorganic filler 5 to 30, foaming agent 0.1 to 2. 4. A filler for a wood-based thermoplastic resin composition, characterized in that the silicone-treated cellulose is obtained by subjecting cellulose to an alcohol infiltration treatment, and then reacting with a polyolefin-compatible resin and then a siloxane polymer to react.