KR200246857Y1 - Resin blend-extruder with pre-woodpowder drying and after-fusing - Google Patents

Abstract

The present invention is effectively dried while being transferred to the molten resin mixing part is transferred to the molten resin mixing unit, and then mixed with the molten resin to inhibit the carbonization of the wood powder when kneading and dispersing extruded to obtain a high quality dry wood powder, and then In order to provide a wood-dried after-melt resin mixing extruder that can be obtained by kneading the wood powder and resin evenly distributed to obtain a high-quality wood flour-resin mixture extruding, coaxial with the first extruder (10) In the conventional co-rotating twin-screw extruder consisting of a second extruder 20 installed in the, the first extruder 10 is a wood powder dryer for drying undried wood powder, the front end of the second extruder 20 On the inner surface 21a of the resin supply cylinder 21 and the contour of the inner hole of the resin supply cylinder 21 and at the beginning part 23a connected to the resin inlet 22 as a closed type of the same type. A co-direction configured to induce a supply of molten resin uniformly to the inside of the cylinder 24 by forming a resin supply guide groove 23 which gradually gives a reverse gradient to the opposite side 23b of the resin inlet 22. It features a wood-dried powder after-melt resin mixing extruder using a rotary twin screw extruder.

Description

Resin blend-extruder with pre-woodpowder drying and after-fusing}

The present invention relates to a mixed extruder for kneading molten resin in wood powder and dispersing and extruding wood flour-resin useful as a compound for various molding materials including building materials and furniture materials. This is an effective method for preventing carbonization and increasing the mixing efficiency of dry wood powder and molten resin to obtain high quality wood powder-resin extrudates with uniform wood powder and resin distribution. will be.

Among the extruders is a twin screw extruder. Even when this extruder appeared, the compound was generally about kneading and dispersing a filler or glass fiber in polypropylene or polyethylene to obtain strand cut pellets. However, with the development of the plastics industry, product quality is required to be advanced and cost reduction is required. Diversification and compounding of plastic materials are progressed, and accordingly, development and rationalization of manufacturing processes have been actively promoted.

As a recycling technique in a twin screw kneading extruder, waste acrylic resin is thermally decomposed in a co-rotating twin screw extruder. Chemical recycling for reuse with gasified monomers has also been made, and techniques for kneading and dispersing coal ash in polypropylene, polyethylene and the like have also been established.

Since then, the technology of interest is a technique of kneading wood discharged in large quantities when processing wood with general-purpose resins such as polypropylene and polyethylene. This is part of an effort to cope with this, as the need for replacement is strong as vinyl chloride resin is mainly caused by environmental problems when kneading and extruding wood flour.

In the filler compound, when the particulate filler is used, the physical properties of impact strength and flexural elasticity are increased. The same is true for wood flour. However, particulate wood powder is difficult to feed into the extruder and the production capacity is reduced. In addition, uniform dispersion of wood powder in the polymer is also required. Therefore, there is a need for a high performance extruder capable of mass discharging and excellent dispersion compounding performance.

Molded products using wood powder compound is considered to be wood containing 50% or more of wood powder. It is widely used as a building material for furniture substitutes, furniture materials, and home appliances.

This wood flour-melt resin co-rotating twin-screw kneader extruder melts and feeds the polymer 3 into the first extruder 1 as illustrated in FIG. 1, and feeds the wood powder 4 from the second extruder 2. The mixture is kneaded and extruded with the molten resin. The wood powder thrown into this extruder was dried at a moisture content of 3%. This is a molten metal kneading extrusion method of linear melted resin.

Wood flour is generally dried using a dryer or a super mixer. The reason for using dried wood flour is that it is necessary to prevent venting and foaming when extruded or compounded by mixing wood flour having a water content of 8% or more with a molten resin.

Wood drying dryers are expensive and potentially explosive. In addition, the super mixer is dried at a moisture content of 1% or less by using the thermal energy obtained by the high speed rotation of the impeller, which is slow in drying and low in efficiency due to the small amount of wood processing per hour with limited capacity.

In addition, the pre-melting resin after the wood flour kneading extruder has a problem that the wood powder is kneaded in the molten resin, and the wood powder carbonization, kneading of the wood powder and resin is inefficient during the pressurization, decompression and pressurization process by the screw.

It is a phenomenon that carbonization occurs because the path from the start of mixing the molten resin and wood flour to the extrusion is long and receives a lot of heat, and the molten resin is not evenly mixed with wood powder in the resin kneading unit.

Carbonized wood flour leads to the deterioration of the wood flour-resin compound, so that even if the molded product is colored with dye, it is not colored and its strength is low.

On the other hand, as in Patent Publication No. 91-289, the inclined surface of which the extrusion end of the disassembly sleeve inserting portion of the second extruder, which supplies the second resin and is mixed and extruded with the first resin, is diagonally opposite from the second resin inlet side with respect to the axis. And a coaxial twin-screw extruder in which a dispensing sleeve in which a plurality of dispensing holes are radially perforated is inserted into the dispensing sleeve insert at a rear end thereof, so that the second resin with respect to the first resin can Since the supply of the resin was not smooth, the mixing of the first and second resins was inefficient, making it difficult to maintain the quality of the two kinds of resin mixed extrudates of high quality.

This has also been pointed out as one of the reasons why the coaxial twin screw extruder is not suitable for wood flour-resin mixing.

The present invention suppresses carbonization when the wood powder put into the extruder is dried toward the molten resin mixture to obtain high quality dry wood powder. It is to provide a wood-melt-drying after-melt resin mixing extruder capable of obtaining a good wood flour-resin mixed extrudate.

The above object is a conventional co-rotating twin screw extruder composed of a second extruder coaxially installed with the first extruder, wherein the first extruder serves as a wood powder dryer for drying undried wood flour, At the tip, the inner side of the resin supply cylinder has a contour of the inner hole of the resin supply cylinder, and is of the same type. This can be achieved by a wood-wood-dried after-melt resin mixing extruder using a co-rotating twin screw extruder configured to induce a uniform supply of molten resin into the cylinder.

1 is a schematic longitudinal cross-sectional view of a conventional co-rotating twin screw extruder

Figure 2 is a schematic longitudinal cross-sectional view in the co-rotating twin screw extruder according to the present invention

3 is a detailed view of a dry wood powder-melt resin mixing portion

4 is a side view as seen from the line A-A of FIG.

<Explanation of symbols for the main parts of the drawings>

10: first extruder 11: screw

12: wood powder dry section 12a: first pressurized section

12b: decompression section 12c: secondary pressurization section

20: second extruder 21: resin supply cylinder

21a: inner side 22: resin inlet

23: resin guide groove 23a: first entrance

23b: opposite side 23c: resin supply guide

In FIG. 2, the first extruder 10 is charged with dry wood powder and dried to a moisture content of about 3-4% while being fed to the molten resin mixing unit by the co-rotating biaxial feed screw 11.

The feed screw 11 is a wood powder drying section 12 for drying undried wood powder, a wood powder-melting resin mixing section 13 for mixing the dried wood powder with a molten resin added later, and a wood powder and molten resin kneading extrusion section ( 14).

The wood flour drying section 12 is a pressure section 12a for compressing the wood powder firstly, because the pitch of the spiral blade is small again, and a reduced pressure section 12b for decompressing the wood powder compressed immediately after the pressurizing section 12a to reduce the feeding density. ) And the second pressure section 12c located immediately after the decompression section 12b.

The wood flour drying section 12 was subdivided into a first pressurization, a reduced pressure, and a second pressurized section while passing through a reduced pressure section 12b in which moisture contained in the wood flour was maintained at a vacuum pressure of 30 to 75 barr under a high temperature atmosphere. After depressurizing the compressed wood powder in the secondary pressure section 12a to induce the moisture of the wood powder to turn into steam, it is quickly carried out through the natural vacuum outlet 17 drilled on the first cylinder 10 of the reduced pressure section 12b. It is intended to effectively prevent carbonization of the wood powder in the drying process by discharging and drying efficiently, and then to perform consolidation mixing with the molten resin supplied from the resin supply unit.

At the beginning of the wood powder dry section 12, the wood powder inlet 15 for inserting the undried wood powder is perforated, and through this, a separate wood powder supply device 16 supplies the undried wood powder with high moisture content. . Although it is undried wood flour, its water content is generally more than 8%. In order to dry the wet wood powder having a high moisture content in the cylinder, the cylinder 10 and the feed screw 11 are inevitably lengthened, and thus, it is unreasonable in many ways, such as an increase in manufacturing cost and a large installation place.

The second extruder 20 is installed at the stop of the first extruder 10. The second extruder 20 mixes the melted resin by injecting the polymer into the resin supply cylinder 21 and mixes the dried wood powder. As shown in FIGS. 3 and 4, the resin supply cylinder 21 A closed resin supply guide groove 23 is formed on the inner side surface 21a of the resin along the inner hole contour of the resin supply cylinder 21.

The structural feature of the resin supply guide groove 23 is that the initial injection portion 23a connecting the resin supply guide surface 23c to the resin inlet 22 has a small volume and the opposite side 23b of the resin inlet 22 has a volume. This is a widely formed point. That is, a reverse gradient is given so that the volume increases from the first inlet portion 23a of the resin supply guide groove 23 to the opposite side 23b.

The difference in the volume of the resin guide surface 23c on the side of the resin supply guide groove 23 toward the first inlet 23a and the opposite side 23b is melted flowing into the cylinder 24 through the resin inlet 22. Before the resin is mixed with the dry wood powder, the molten resin is temporarily increased in density at the beginning of the inflow, and the volume of molten resin is controlled by a certain pressure by facilitating the flow of the molten resin in order to facilitate a flow of a reduced pressure in the process of gradually expanding the volume. In order to increase the acidity, a sufficient amount of molten resin is uniformly supplied to the opposite side 23b so as to absolutely contribute to inducing the uniform mixing of the wood powder and the molten resin as a whole.

There are two ways to do this. As shown in FIG. 5, the method of extending the supply volume of the molten resin by increasing the length of the opposite side 23b of the resin supply guide groove 23 is one. The resin supply guide of the resin supply guide groove 23 is shown in FIG. 6. The width of the opposite side 23b of the groove 23 is expanded to increase the supply volume of the molten resin.

In either case, the molten resin supplied through the resin guide groove 23 is uniformly supplied to the inside of the cylinder 24 so as to surround the wood powder dried in the previous process, so that mixing with the wood powder is made highly efficient and efficient. will be.

In FIG. 2, when the dry wood powder is introduced into the wood powder inlet 15 of the first extruder 10 while the electric heater mounted on the cylinder is operated, the co-rotating biaxial screw 11 that is already in operation is operated. Is pressed toward the resin inlet 22 of the second extruder 20.

In this process, the wood powder is compressed when passing through the pressure section 12a, and then dried as it is dispersed while passing through the pressure reducing section 12b maintained in the high temperature vacuum atmosphere, and the steam is removed through the vacuum outlet 17. . When the decompression section 12b is in a non-vacuum state, an undesirable situation occurs in which wood powder is sucked by the vacuum pressure acting on the vacuum discharge section 17. In order to prevent this from happening, the wood dry section 12 must be maintained in a vacuum atmosphere.

The wood powder dried through this process is compressed again in the second pressure section 12c and is conveyed to the molten resin supply cylinder 21. If the density of the dried wood flour is low, the mixing with the molten resin is not performed properly. When undried wood flour having a water content of 8% or more passes through the drying section 12, its water content is significantly lowered to 3% or less. The moisture content of dry wood flour must be maintained at 3% because it is essential to prevent carbonization of wood flour during kneading and dispersing with molten resin. Thereafter, the trace amount of water remaining in the wood powder is removed from the at least one vent part 17. The 2nd extruder 20 melt | dissolves the injected polymer, and supplies it to the resin supply cylinder 21, and the process of kneading-dispersing with dry wood powder is performed. The molten resin enters the resin supply guide groove 23 through the resin injection port 22.

Thereafter, the molten resin flows along the resin supply guide groove 23 which gradually increases in width, flows into the band-shaped molten resin, and becomes tubular molten resin when it is filled to the opposite side 23b. Then mix it in the dry wood powder as if it were surrounded.

The temperature of the molten resin is higher than that of dried wood flour. The temperature of the two was mixed with the molten resin to obtain an intermediate temperature. Compared to the conventional molten resin-undried wood flour simultaneous injection followed by dry extrusion, this is another important clue that the carbonization of wood flour is prevented due to the low temperature of wood flour.

The wood flour and the molten resin are mixed and then uniformly mixed in the wood flour-resin mixing section 13, and kneaded and dispersed while being extruded through the kneading extrusion section 14.

As described above, the present invention is a method of mixing wood flour by the first extruder of the co-rotating twin screw extruder and post melt resin mixing method by the second extruder to prevent carbonization of the wood powder while drying the undried wood powder itself. A high quality mixed extrudate can be obtained with high efficiency.

Claims (1)

In a conventional co-rotating twin screw extruder consisting of a second extruder coaxially installed with a first extruder, the first extruder 10 serves as a wood powder dryer for drying undried wood flour, and the second extruder 20 At the front end of the resin supply cylinder 21, on the inner surface 21a of the resin supply cylinder 21, and the contour of the inner hole of the resin supply cylinder 21, the resin guide groove 23 from the first inlet 23a connected to the resin inlet 22 as a closed type. A reverse direction gradient to the opposite side 23b) to form a resin supply guide groove 23 which gradually widens, thereby inducing the supply of molten resin uniformly to the inside of the cylinder 24. Wire wood powder dry melt resin extruder using a rotary twin screw extruder.