JP3426898B2 - Extrusion pressure regulator and method for extruding wood plastic - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique relating to extrusion molding of wood-like wood plastic, and more specifically to a pressure regulator and a pressure regulator for adjusting the extrusion pressure during the extrusion of wood plastic. It relates to the manufacturing method.

[0002]

2. Description of the Related Art Various techniques have been provided for producing a so-called wood plastic molded article by mixing a powder of natural wood (wood flour) with a resin. P from among them
CTJP94 / 00351 (International Publication Number; WO94
/ 20280) "Cellulose-based fine powder particles,
The technology of "wood-like molded product and wood-like product" will be briefly described.

Crushed powder obtained by crushing a cellulosic material as a raw material is ground to obtain powder particles having an increased bulk specific gravity, and the outer peripheral surface of the powder particles has a surface diameter smaller than and harder than the powder particles. Are fixed to form fixed particles, and the fixed particles are mixed with a resin and a pigment and melted, and thereafter or simultaneously with melting, molded into a desired shape by extrusion molding or injection molding. Then, it is possible to provide a method for producing a wood-like product and a wood-like product which have a pattern extremely close to the grain of a natural tree on the surface and have a texture such as a touch feeling similar to that of the natural tree.

[0004]

However, there has been a problem that there is no established technique regarding the wood texture of the molded product in the above-mentioned molding technique of the wooden plastics. This will be described in more detail. One of the conditions for determining the texture of wood is whether the mixing ratio of wood powder (crushed powder of cellulose material, “fixed particles” in the case of PCTJP94 / 00351) to resin is high or low. That is, the higher the mixing ratio of the wood powder (fixed particles) to the resin, the more the wood texture is obtained. On the other hand, if the mixing ratio is high, the molding itself may be difficult, for example, it takes time to knead the resin, and defective molding easily occurs.

An object to be solved by the present invention is to provide a technique for forming a wooden plastic which is relatively easy to form while enhancing the texture of wood. Here, an object of the invention as set forth in claim 1 is to provide an extrusion pressure regulator that contributes to relatively easily performing molding while improving the texture of wood. Further, an object of the inventions of claims 2 and 3 is to provide an extrusion molding method for wood plastics which can be molded relatively easily while enhancing the texture of wood.

[0006]

The present invention is to achieve the above-mentioned object. (Claim 1) The extrusion pressure adjuster according to claim 1 is an extrusion pressure applied to a resin material after the resin material is melted and before it is delivered to a mold in the extrusion molding of wood plastic in which wood powder is mixed with resin. In the extrusion pressure regulator, the passage of the resin material is formed so as to narrow gradually and discontinuously toward the mold side.

(Definition of term) "Resin" means a resin suitable for extrusion molding of wood plastics, and includes hard resin and soft resin, for example, vinyl chloride resin, expanded vinyl chloride resin, polyethylene resin, polypropylene resin. , Phenol resin, urethane resin, polyurethane resin, ABS resin, polystyrene resin and the like. It is determined by the function and application of the desired molded product.

The "wood flour" may be crushed powder of natural wood and sawdust thereof, as well as crushed powder of rice straw, bacas and the like. In addition, the wood powder specified in claim 3 is included.
The “stepwise and discontinuous” configuration means, for example, a configuration that is formed stepwise in the cross-sectional shape in the extrusion direction.
The stage is determined by various conditions such as the properties of the resin material and the type of final molded product. If the number of steps is too large, the discontinuity becomes close to continuous, so an appropriate number of steps is selected for the surface desired for the molded product.

(Operation) The operation of the extrusion pressure regulator according to claim 1 will be described. When the melted resin material is fed into the extrusion pressure regulator, the path becomes resistance and the pressure increases at the part formed to narrow gradually and discontinuously, and the kneading of the resin material proceeds. . Further, the resin is rubbed against the inner wall of the extrusion pressure regulator and remains there. As a result, the wood powder contained in the resin material floats relatively near the surface of the mold. Therefore, it is possible to provide a molded product having a high wood feel relative to the content of wood powder. In other words, since the content of wood powder is small, it is possible to reduce troubles such as defective molding that are likely to occur when the content of wood powder is large. (Claim 2) According to the invention of Claim 2, in the extrusion molding of a wood plastic in which wood powder is mixed with a resin, the extrusion pressure applied to the resin material is stepwise after the resin material is melted and before it is sent to a mold. In addition, the method is an extrusion molding method for wood plastics, which is characterized by increasing the height discontinuously. (Claim 3) The extrusion molding method for wood plastic according to claim 3,
The extrusion molding method of the wood plastic according to claim 2 is technically limited, and the "wood flour" used in the extrusion molding method of the wood plastic according to claim 2 is a ground grain powder, It is characterized in that surface particles having a diameter smaller than that of the powder particles and hard surface particles are fixed to the outer peripheral surface of the powder particles.

Incidentally, in order to bring it closer to real wood, a pigment is often contained. The "pigment" is a colored pigment and is, for example, an inorganic pigment such as iron oxide, cadmium yellow, or carbon black, or an organic pigment. (Definition of terms) "A method of fixing surface particles having a smaller diameter and harder than the powder particles on the surface of the powder particles" is, for example, grinding with a ball mill, high-speed stirring with a high-speed rotary blade mixer for a long time, etc. There is a method. The treatment for removing the fluff of the fibers of the cellulosic material may be performed separately from the fixing of the surface grains.

"Surface grains" are metals, compounds of metals such as titanium oxide, ferrite, aluminum, nickel, silver, calcium carbonate, and non-metals such as ceramics. (Function) When the wood powder is limited as in claim 3, a molded product having a feel closer to that of a real wood than that of a normal wood plastic can be obtained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail with reference to the embodiments and the drawings. The drawing used here is FIG. FIG. 1 is a conceptual diagram of the present invention.
First, the configuration of this embodiment will be described. The extrusion pressure adjuster shown in this embodiment adjusts the extrusion pressure applied to the resin material after the resin material is melted and before it is sent to the mold in the extrusion molding of wood plastic in which wood powder is mixed with resin. In the extrusion pressure regulator, the passage of the resin material is formed so as to narrow gradually and discontinuously toward the mold side.

Here, the resin material will be described in detail. The “resin” is a resin suitable for extrusion molding of wood plastic, and is vinyl chloride resin in this embodiment. Also,
The "wood flour" mixed with the resin is a finely crushed sawdust into finely ground powder particles, and the outer peripheral surface of the powder particles is
Surface particles having a diameter smaller than that of the powder particles and being hard were fixed. In addition to such resin and wood flour, a pigment is added to form a pellet in advance to give a wood-like pellet.
Prepare multiple types of wood-like pellets by changing the type of pigment. The plurality of types of wood-like pellets are melted, mixed, and sent to the above-mentioned extrusion pressure regulator before being sent to the mold.

The molten resin material is extruded from a cylinder having a diameter of 50 mm. This extrusion pressure regulator is made of iron and has a two-step stepped cross-section in the extrusion direction. The cylinder side inner diameter is 30 mm, the die side inner diameter is 25 mm, and the extrusion direction length is It is 100 mm. A member called a "core" that adjusts the flow of resin is often installed between the cylinder and the extrusion pressure adjuster. The core is
Since the flow condition may be finely adjusted after installation,
It is common to use brass for easy cutting.

When the melted resin material is fed into the extrusion pressure regulator, the path becomes a resistance and the pressure becomes high at a portion formed so as to become narrow in a stepwise and discontinuous manner. Ren progresses. Further, the resin is rubbed against the inner wall of the extrusion pressure regulator and remains there. As a result, the wood powder contained in the resin material floats relatively near the surface of the mold. Therefore, it is possible to provide a molded product having a high wood feel relative to the content of wood powder. In other words,
Since the content of wood powder is small, it is possible to reduce troubles such as defective molding which are likely to occur when the content of wood powder is large.

Further, since the wood powder is limited as described above, a molded product having a feeling closer to that of a real wood than a normal wood plastic can be obtained. However, the present invention also relates to the production of a normal wood plastic. An extrusion pressure regulator or core can be used.

[0017]

According to the first aspect of the present invention, it is possible to provide an extrusion pressure regulator that contributes to relatively easy molding while improving the texture of wood. Further, according to the inventions of claims 2 and 3, it is possible to provide an extrusion molding method for wood plastics which can be molded relatively easily while enhancing the texture of wood.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of the present invention.

─────────────────────────────────────────────────── ─── Continued Front Page (72) Kenji Ogawa 2-4-5 Takaido East, Suginami-ku, Tokyo Misawa Homes Co., Ltd. (72) Yoshinori Nakano 2-4-5 Takaido East, Suginami-ku, Tokyo Misawa Homes (72) Inventor Yoshiaki Kobayashi 2-4-5 Takaido Higashi, Suginami-ku, Tokyo Misawa Homes Co., Ltd. (72) In-house Masami Kato 2-4-5 Takaido Higashi, Suginami-ku, Tokyo Misawa Homes ( 56) References JP-A-4-73123 (JP, A) JP-A-8-238607 (JP, A) JP-A-9-11303 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 47/00-47/96

Claims (3)

(57) [Claims] 1. In extrusion molding of a wood plastic in which wood powder is mixed with a resin, after melting the resin material and before sending it to a mold,
An extrusion pressure adjuster for adjusting an extrusion pressure applied to a resin material, characterized in that a passage of the resin material is formed so as to narrow gradually and discontinuously toward a mold side. . 2. In extrusion molding of a wood plastic in which wood powder is mixed with a resin, after melting the resin material and before sending it to a mold,
An extrusion molding method for wood plastics, characterized in that the extrusion pressure applied to the resin material is increased stepwise and discontinuously. 3. The wood powder is ground powder, and surface particles having a smaller diameter and a harder surface than the powder particles are fixed to the outer peripheral surface of the powder particles. 2. An extrusion molding method of wood plastic according to 2.