KR20020024094A - Method and apparatius for resin mixing and extruding with previously dry and later fusion, using lottery double axle extruder - Google Patents

Abstract

PURPOSE: A method and an apparatus for extruding resin mixture using one-directional rotating type biaxial extruders are provided to improve the efficiency of production of high quality and high strength resin mixture while preventing the carbonization of them by mixing wood meal or waste vegetable fiber into molten resin after drying them. CONSTITUTION: In the extruding method and apparatus using one directional rotating type biaxial two extruders, wet wood meal is dried first by using a first extruder(10), and then molten resin is supplied through a resin supply guide groove of a second extruder(20) located at the middle part of the apparatus. After that, the dried wood meal and the molten resin are uniformly distributed and mixed while dehydrating the remaining moisture in the wood meal on at least one vacuum bent portions(19a,19b) before extruding the resin mixture.

Description

Pre-drying post-melt resin mixing extrusion method using co-rotating twin screw extruder and its apparatus {Method and apparatius for resin mixing and extruding with previously dry and later fusion, using lottery double axle extruder}

The present invention kneading and extruding wood flour or vegetable waste fibers and molten resin, and the method for producing wood powder or vegetable waste fibers useful as a compound for various moldings, including building materials, furniture materials by dispersing and mixing the resin alone or in a fixed ratio and then extruded The present invention relates to an apparatus for preventing carbonization when wood powder or vegetable waste fibers fed into an extruder are dried toward a molten resin mixing unit, and increasing the efficiency of mixing wood flour or dry vegetable waste fibers with molten resin, thereby improving wood flour or vegetable waste. The present invention relates to a pre-drying post-melt resin mixed extrusion method and apparatus for obtaining high quality wood flour or vegetable waste fiber- resin mixed extrudates having a uniform distribution of fibers and resins and excellent physical strength.

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, the waste acrylic resin is pyrolyzed in a co-rotating twin screw kneading extruder. Chemical recycling for recycling into gasified monomers has also been made, and techniques for kneading and dispersing coal ash in polypropylene and polyethylene are also 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 above-mentioned pre-melting resin post-wood flour kneading extruder is a problem that the wood powder carbonization and kneading of the wood powder and resin are inefficient while the wood powder is kneaded in the molten resin and subjected to pressurization, depressurization and pressurization by a 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, and even the dyeing of the moldings made from it does not produce color and improve physical strength.

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 biaxial extruder in which a dispensing sleeve having a plurality of dispensing holes radially perforated is inserted into the dispensing sleeve insert at a rear end thereof, and the second biaxial extruder has a second shape relative to the first resin due to the wrong selection of the inclined surface direction and the distance between the dispensing holes. 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 the carbonization when the dry wood powder or undried vegetable waste fiber fed into the extruder is transported toward the molten resin mixing unit to obtain high quality dry wood powder or vegetable waste fiber, and then kneaded and dispersed efficiently with the molten resin. Wood flour or vegetable waste fiber and resin is uniformly distributed to provide a good dry wood melt or vegetable waste fiber-resin mixture extruding method to obtain a good quality of wood flour or vegetable waste fiber-extruded mixture.

Another object of the present invention is to provide an extrusion apparatus which is particularly suitable for the pre-drying after-melt resin mixing extrusion method.

The above first object is a conventional co-rotating twin-screw or single screw extruder consisting of a conventional co-rotating biaxial first extruder and a second extruder installed coaxially, using the first extruder undried wood powder Alternatively, when the undried vegetable waste fibers are dried, and the dried wood powder or vegetable waste fibers are mixed with the molten resin in the second extruder and extruded, the pre-drying is carried out by effectively uniformly supplying the amount of molten resin and kneading dispersion. It can be achieved by a post-melt resin mixed extrusion method.

Said 2nd subject is a normal co-rotating biaxial or single screw extruder which consists of a normal co-rotating biaxial 1st extruder and the 2nd extruder provided coaxially, WHEREIN: Undried wood powder or undried in a 1st extruder Secure the drying and water devolatilization section that devolatilizes water vapor generated while drying the vegetable waste fibers, and in the resin supply guide groove formed in the second extruder, the resin induction surface has a small volume at the first entrance connected to the resin inlet and the opposite side of the resin inlet. Before the molten resin flowing into the cylinder through the resin inlet is mixed with dry wood powder or vegetable waste fiber, the density of the molten resin is temporarily increased at the beginning of the inflow, and the volume gradually spreads toward the wider volume. The pressure is reduced and the molten resin flows smoothly. In order to increase the dispersibility of the molten resin, a sufficient amount of molten resin may be constantly supplied to the opposite side, and the powder may be extruded by an extruder configured to uniformly mix wood flour or vegetable waste fibers with the molten resin.

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

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

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

FIG. 4 is a side shave of a dry wood powder-melt resin mixing part viewed from the line A-A of FIG.

5 is a cross-sectional view of a wood powder-melt resin mixing unit according to another embodiment

6 is a cross-sectional view of a wood-melt resin mixing portion according to another embodiment

<Explanation of symbols for main parts of the drawings>

10: first extruder 11: screw

12: wood flour-vegetable waste fiber dry section 12a: first press section

12b: decompression section 12c: secondary pressurization section

20: second extruder 21: resin supply cylinder

21a: inner side 22: resin inlet

23: resin supply guide groove 23a: initial insertion

23b: opposite side 23c: resin guide surface

In FIG. 2, the first extruder 10 is dried so as to have a moisture content of 3% or less while injecting undried wood powder or vegetable waste fibers and feeding them to the molten resin mixing portion by a co-rotating biaxial feed screw 11.

The feed screw 11 is a wood powder for drying undried wood powder or a dry section 12 for vegetable waste fibers, a wood powder-melt resin mixing section 13 for mixing the dried wood powder with a molten resin added later, and wood powder and molten wood. It is divided into the resin kneading extrusion section (14). The dry section 12 for wood flour or vegetable waste fiber is also a moisture devolatilization section.

The wood flour or vegetable waste fiber drying section 12 is compressed by pressing the compressed wood segment or vegetable waste fiber immediately after the pressurization section 12a for compressing the wood powder firstly, and the compressed wood powder or vegetable waste fiber after the compression section 12a is small. It is subdivided into the decompression section 12b which lowers a density, and the 2nd press section 12c located immediately after the decompression section 12b.

As such, the dry section 12 for wood flour or vegetable waste fiber was subdivided into first pressurization, decompression and secondary pressurization sections, and the moisture contained in the wood flour or vegetable waste fiber was maintained in a vacuum of 30 to 75 barr under high temperature atmosphere. While decompressing the wood flour or vegetable waste fibers compressed in the first pressurization section 12a while passing through the decompression section 12b, the water of the wood flour or vegetable waste fibers is converted into steam and then the first portion of the decompression section 12b. Rapidly discharged through the vacuum outlet 17 perforated on the cylinder 10 to efficiently dry and dehydrate the moisture to effectively prevent carbonization of wood flour or vegetable waste fibers in the drying process, and then the molten resin supplied from the resin supply unit And consolidation mixing to achieve.

At the beginning of the dry section 12 for wood flour or vegetable waste fiber, an inlet 15 for injecting the undried wood flour or vegetable waste fiber is perforated, and through this, a predetermined amount of high moisture content is provided by a separate supply device 16. It will supply dry wood flour or vegetable lung fibers. Undried wood flour or vegetable waste fiber refers to a moisture content of 8% or more. In order to dry the wet wood powder or vegetable waste fiber with high moisture content in the cylinder 10, the cylinder 10 and the feed screw 11 are inevitably lengthened, so it is unreasonable in many ways, such as an increase in manufacturing cost and a lot of installation place.

In FIGS. 3 and 4, the second extruder 20 installed in the middle of the first extruder 10 is a wood flour or vegetable waste which has been dried by forcibly injecting a molten resin into the resin supply cylinder 21. 3 and 4, a closed resin supply guide groove 23 is formed on the inner surface 21a of the resin supply cylinder 21 along the inner hole contour of the resin supply cylinder 21. Formed.

The structural feature of the resin supply guide groove 23 is that the first inlet portion 23a connecting the resin 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. It is a widely formed point. The difference in the volume of the resin guide surface 23c of the resin guide groove 23 into the opposite side 23b and the opposite side 23b means that the molten resin flowing into the cylinder 24 through the resin injection port 22 Prior to mixing with dry wood flour or vegetable waste fibers, the molten resin is temporarily increased in density at the beginning of the inflow, and the molten resin is kept at a constant pressure by facilitating the flow of the molten resin in order to promote a kind of reduced pressure atmosphere in the process of gradually increasing the volume. In order to increase the dispersibility of the molten resin uniformly supplied to the opposite side (23b) is constantly contribute to induce uniform mixing of the wood flour or vegetable waste fibers and the molten resin as a whole.

Various means can be taken to achieve the above object. The first means is to give a gradient to increase the volume from the inlet (23a) of the resin supply guide groove 23 to the opposite side (23b) as shown in FIG. The second means, as shown in Fig. 4, is to achieve the same purpose by expanding the volume of the opposite side 23b of the resin supply guide groove 23 by length or width. 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 and mixed with the wood powder or vegetable waste fiber, as if the wood powder or vegetable waste fiber was dried in the previous process. This high efficiency and high efficiency will be achieved.

In FIG. 2, when the dry wood powder or vegetable waste fiber is introduced into the inlet 15 of the first extruder 10 while the electric heater installed in the cylinder is operated, the coaxially rotating biaxial screw ( 11) to the resin inlet 22 of the second extruder 20.

In this process, wood flour or vegetable waste fibers are compressed when passing through the pressure section 12a, and then dried while passing through the pressure reducing section 12b maintained at a high temperature vacuum atmosphere, whereby steam is removed through the vacuum outlet 17. As a result, drying is accelerated. When the decompression section 12b is in a non-vacuum state, an undesirable situation occurs in which wood flour or vegetable waste fiber, which is a material to be dried, is sucked to the vacuum pressure acting on the vacuum discharge unit 17 side. To prevent this from happening, the dry section 12 for wood flour or vegetable waste fibers 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 or vegetable waste fiber 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 or vegetable waste fiber should be maintained at 3% because it is necessary to prevent carbonization of wood flour or vegetable waste fiber during kneading and dispersing with molten resin.

Subsequently, traces of water remaining in wood flour or vegetable waste fibers are removed from at least one vacuum vent unit 19a, b. Reference numeral 18 denotes a natural vent.

The second extruder 20 melts the introduced polymer and supplies it to the resin supply cylinder 21 to knead and disperse the dried wood powder or vegetable waste fibers. The molten resin enters the resin guide groove 23 through the resin injection port 22.

Thereafter, the molten resin spreads along the resin guide groove 23 gradually increasing in width, flows into the band-shaped molten resin, and becomes tubular molten resin when it is filled to the opposite side 23b. This is mixed with dried wood powder or vegetable lung fibers as if it were enclosed.

The temperature of the molten resin is higher than that of dried wood flour or vegetable waste fibers. The temperature of the two was mixed with the molten resin to obtain an intermediate temperature. Compared to the conventional molten resin-dried wood flour or the method of dry extrusion after simultaneous feeding of vegetable waste fiber, the temperature of the wood flour is low, which is another important clue that prevents carbonization of wood flour.

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

As described above, the present invention is a method of mixing the pre-drying by the first extruder and the post-melt resin mixing method by the second extruder of the co-rotating twin screw extruder while carbonizing the wood powder or vegetable waste fiber while self-drying the undried wood flour or vegetable waste fiber. It is possible to obtain high quality mixed extrudates quickly and efficiently with high efficiency.

In addition, the resin guide surface of the resin supply guide groove for the second extruder forms a small volume of the first inlet connected to the resin inlet, and the opposite side of the resin inlet forms a large volume so that the molten resin flowing into the cylinder through the resin inlet is dried. Alternatively, the density of the molten resin is temporarily increased at the beginning of inflow prior to mixing with the vegetable waste fibers, and the pressure is encouraged as the volume is gradually spread to the wider side, so that the molten resin flows smoothly. As a result, a sufficient amount of molten resin is constantly supplied to the opposite side of the resin feed guide groove, so that wood flour or vegetable waste fiber and molten resin are uniformly mixed throughout, and thus, fine wood flour or vegetable waste fiber-melt resin mixed extrudates Can be obtained.

Claims (7)

Pre-drying the pre-dried wood flour using the first extruder in a conventional co-rotating twin screw or single screw extruder comprising a conventional co-rotating biaxial first extruder and a second extruder installed coaxially. The co-rotating twin screw extruder, characterized by kneading and dispersing uniformly wood powder and the molten resin supplied through the resin supply guide groove of the second extruder by devolatilizing and extrudes a small amount of water remaining in the wood powder from the vacuum vent unit. Pre-drying after-melt resin mixing extrusion method using. 2. The pre-drying post-melt using the co-rotating twin screw extruder according to claim 1, wherein the resin supply guide groove increases the amount of supply of molten resin opposite to the initial portion of the resin inlet so that dry wood powder and molten resin are uniformly kneaded. Resin mixed extrusion method. 3. The pre-drying according to claim 2, wherein the resin supply guide surface is gradually gradientd wider from the initial entry portion of the resin supply guide groove toward the opposite side as a means for increasing the supply amount of the opposite side molten resin. Post-melt resin mixing extrusion method. The line using a coaxial rotary twin screw extruder according to claim 2, wherein the resin guide surface extends only the volume of the portion located at the opposite side of the resin feed guide groove as a means for increasing the supply amount of the opposite side of the molten resin. Melting resin mixed extrusion method after drying. The method of claim 1, wherein the undried wood powder is a pre-drying post-melt resin mixed extrusion method using a co-rotating twin screw extruder comprising a proportion of undried vegetable waste fibers. Predrying undried vegetable waste fibers using the first extruder in a conventional co-rotating twin screw or single screw extruder consisting of a conventional co-rotating biaxial first extruder and a second extruder installed coaxially. And uniformly kneading and dispersing the pre-dried vegetable waste fiber with the molten resin supplied through the resin supply guide groove of the second extruder to devise a trace amount of moisture remaining in the vegetable waste fiber by devolatilization in a vacuum vent unit. Pre-drying post-melt resin mixing extrusion method using co-rotating twin screw extruder. A conventional co-rotating twin screw or single screw extruder comprising a conventional co-rotating biaxial first extruder and a second extruder installed coaxially, wherein the first extruder is used to feed undried wood flour and / or vegetable waste fibers. The dry drying section combined with pre-drying moisture is formed, and the resin guide surface of the resin supply guide groove of the second extruder is formed to have a small volume of the inlet part connected to the resin inlet port, and the opposite side of the resin inlet port is made wider to form a molten resin. Pre-drying post-melt resin mixed extrusion apparatus using a co-rotating twin screw extruder, characterized in that a sufficient amount of molten resin is supplied to the opposite side of the resin supply guide groove by increasing the dispersibility