JP2904770B1 - Method for producing waste paper-containing resin composition and mixing apparatus - Google Patents

Abstract

The present invention provides a method and an apparatus for uniformly dispersing used paper fine powder in a resin, and a used paper-containing resin composition which does not cause surface roughening or reduced strength during article molding. SOLUTION: In a method for producing a waste paper-containing resin composition by mixing waste paper fine powder and resin powder, a step of removing long fibers in the waste paper fine powder, and a step of mixing waste paper fine powder and resin powder Including a step of kneading the obtained mixture, a step of granulating the kneaded resin composition, and mixing the used paper fine powder and the resin powder in the mixing step by a stirring blade rotating in a vertical direction for a predetermined time, thereby obtaining The mixed mixture is intermittently discharged from the bottom of the mixing tank, and the discharged mixture is continuously supplied to the kneading machine to remove moisture from at least two exhaust ports provided in the kneading machine while kneading. A method for producing a used paper-containing resin composition, and a mixing apparatus used in the method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a waste paper-containing resin composition and a mixing apparatus, and more particularly to a method for effectively utilizing surplus waste paper, which has high strength and light weight and combustion during incineration. The present invention relates to a method for producing a resin composition and a mixing apparatus, which have low calories and do not damage an incinerator.

[0002]

2. Description of the Related Art Conventionally, various molded articles made of various synthetic resins have been produced and used in large quantities. Various fillers are added and mixed to these resin molded products according to various purposes. Although there are various purposes for adding the filler, one of the purposes is to recycle the waste, and the present inventor has previously recycled the excess waste paper by pulverizing the excess waste paper and mixing it with the resin. Proposed.

[0003]

In order to uniformly mix the used paper with the resin and obtain various molded products without any deterioration in physical properties, it is essential to pulverize the used paper. The specific gravity of the pulverized powder is very small, while the specific gravity of the resin is usually around 1, so that it is very difficult to mix both uniformly. For this reason, poor dispersion of the used paper fine powder in the resin occurs, for example, when formed into a film, the film surface is roughened, a large number of pinholes are generated, the strength is reduced, and further, when the film is printed, Good printing was difficult.

[0004] In addition, ordinary paper absorbs and retains a considerable amount of water (usually 8% by weight or more). Therefore, when fine powder of waste paper is mixed with a resin and the mixture is formed into various articles,
Moisture evaporates due to heat during molding, and a number of bubbles are generated in the molded product, which causes problems such as roughening of the surface of the molded product and reduction in the strength of the molded product. Accordingly, an object of the present invention is to provide a method and an apparatus for uniformly dispersing used paper fine powder in a resin, and when forming into various articles, a used paper-containing resin composition which does not cause roughening of the surface of the molded product or a decrease in strength. It is to provide things.

[0005]

The above object is achieved by the present invention described below. That is, the present invention provides a method for producing a waste paper-containing resin composition by mixing waste paper fine powder and resin powder, wherein a step of removing long fibers in the waste paper fine powder is provided.
A step of mixing the used paper fine powder and the resin powder, a step of kneading the obtained mixture, and a step of granulating the kneaded resin composition, and rotating the used paper fine powder and the resin powder in the longitudinal direction in the mixing step. Mixing for a predetermined time by the stirring blade,
The obtained mixture is intermittently discharged from the bottom of the mixing tank, and the discharged mixture is continuously supplied to the kneader to remove moisture from at least two exhaust ports provided in the kneader while kneading. A method for producing a waste paper-containing resin composition characterized by the above features, and a mixing apparatus used in the method are provided.

[0006]

Next, the present invention will be described in more detail with reference to preferred embodiments. The resin used in the present invention is a general-purpose resin such as low-density polyethylene, high-density polyethylene, polyvinyl chloride, polystyrene, polypropylene, and polyester, and particularly when used for packaging films such as garbage bags, low-density polyethylene. High density polyethylene is preferably used. These resins are pulverized and used by various known methods. In the present invention, the preferred particle size of the resin powder is 20-60 mesh pass particles. If the resin powder is larger than this range, uniform mixing with the used paper fine powder becomes difficult.

The used paper fine powder used in the present invention is obtained by finely pulverizing used paper such as used newspapers, magazines, and cardboards. The crushing method and crushing apparatus used for crushing the used paper may be any of conventionally known methods, and for example, crushing is preferably performed by a crusher, Super Cyclone manufactured by Murata Co., Ltd. In the case of the used paper fine powder, pulverized materials having various particle sizes can be obtained.
It is preferable to pulverize to a mesh pass. If the particle size is larger than this, the waste paper fine powder tends to agglomerate, and the uniform dispersion in the resin becomes insufficient. The waste paper fine powder thus obtained is dried as much as possible, and its water content is reduced to 8% by weight.
Hereinafter, it is desirable to set the content to preferably 2 to 5% by weight. The mixing ratio of the resin powder to the waste paper fine powder is generally 5 to 7 per 100 parts by weight of the resin powder.
0 parts by weight, preferably in the range of 10 to 60 parts by weight.
If the used amount of the used paper fine powder is too small, the recycling efficiency of the used paper is insufficient, while if the amount of the used paper fine powder is too large, for example, even if it is finally formed into a film having a thickness of 10 to 100 μm, , Cannot be formed into a film.

FIG. 1 shows a process chart of the manufacturing method of the present invention.
This will be described more specifically with reference to FIG. In FIG. 1, the finely ground waste paper powder is first sieved before being mixed with the resin powder. The long fibers contained in the pulverized material are removed by the sieve. When the removal of long fibers is performed with a sieve vibrating in the longitudinal direction, a part of the long fibers mixed in the pulverized material passes through the sieve, so that the removal of the long fibers is insufficient, and in the present invention, A 100-mesh horizontal vibrating screen is used. By using the screen vibrating in the horizontal direction, long fibers having a length of about 0.1 mm or more are substantially removed from the used paper fine powder. It is important to remove the long fibers, and if the long fibers are still mixed in the waste paper fine powder, the waste paper fine powder is liable to agglomerate due to the presence of the long fibers when mixed with the resin powder, and the waste paper fine powder is used. And the resin powder are not evenly mixed, resulting in a final thickness of 10 to 100
It cannot be formed into a μm film.

The waste paper fine powder from which the long fibers have been removed and the resin powder are uniformly mixed in a suitable mixer. In this mixing, since the specific gravity of the waste paper fine powder and the specific gravity of the resin powder are greatly different, it is important to select a mixer. In the present invention, good results were obtained by using a mixer as shown in FIGS. 2 and 3 as a suitable mixer. FIG. 2 is a diagram schematically showing a cross section viewed from one side of the mixer used in the present invention, and FIG. 3 is a diagram schematically showing a cross section viewed from the other side. The mixer shown in FIGS. 2 and 3 includes a mixing tank 1, a vertically rotating stirring blade 2 provided in the mixing tank 1, and a mixture discharge port 4 provided in a bottom 3 of the mixing tank 1. And a supply path 5 for supplying the discharged mixture to the kneading machine and a kneading machine 6, and the bottom 3 of the mixing tank 1 is close to the rotation locus of the stirring blade 2 rotating in the vertical direction as shown in FIG. Is formed in a substantially U-shape, and a discharge port 4 for the mixture is provided near the lowermost point of the bottom 3, the discharge port 4 is opened intermittently, and the mixture is configured to drop by its own weight. I have.

The shape of the mixing tank 1 of the above mixer may be any shape, but in the example shown in the drawing, the upper section is rectangular, and the bottom 3 is substantially U-shaped as shown in FIG. It has a character shape. A chute 8 is provided below the U-shaped bottom 3 so that the mixed powder is accumulated on a screw 7 for conveying the mixed powder. The internal volume of such a mixing tank 1 is determined by the required mixing processing capacity, but usually about 130 to 140 kg is appropriate. On the upper surface of the mixing tank 1, a waste paper fine powder input port 9 and a resin powder input port 10 are provided.
First, the used paper fine powder is first supplied into the mixing tank 1 at a predetermined ratio, and then the resin powder is supplied.

In the mixing tank 1, there is provided a stirrer including a rotating shaft 11 rotated by a motor (not shown) and a plurality of rotating blades 2 attached to the rotating shaft 11.
By the rotation of the stirring blade 2 in the vertical direction, the fine powder of waste paper and the resin powder are uniformly mixed. The tip of the rotary blade 2 rotates in the vertical direction in proximity to the U-shaped bottom 3, and the waste paper fine particles and the resin powder are mixed. At this time, the rotation speed of the rotary blade 2 is usually 15 to 30 rpm. On the other hand, in a device in which the rotating blades rotate in the horizontal direction, due to the difference in specific gravity between the resin powder and the waste paper fine powder, the two are rather separated by centrifugal force, and uniform mixing of the two is impossible.

After the waste paper fine powder and the resin powder are sufficiently mixed by the stirring blade 2 rotating in the vertical direction, one or preferably two or more discharge ports 4 provided on the U-shaped bottom 3 are provided. Then, the mixed powder is discharged by its own weight, and falls onto a transport screw 7 provided at a lower portion. A cover 12 is provided on the surface of the outlet 4 to cover the outlet 4. The cover 12 is supported by a rotating shaft 13 that rotates in conjunction with a drive source (not shown). By the rotation of the rotating shaft 13, the lid 12 is separated from the U-shaped bottom 3 as shown by an arrow, and the outlet 4 is opened.

The discharged mixed powder falls onto a conveying screw 7 provided below the discharge port 4 and is
Is dropped into the hopper 14 of the kneading machine 6 by its own weight by the screw 7 rotating and supplied. A weighing device (not shown) is provided in the hopper 14, and the rotating shaft 1 supporting the weighing device and the lid 12 for the discharge port 4 is provided.
3 are electrically connected as shown by a dotted line,
When the mixture in the hopper 14 becomes less than a predetermined amount,
The signal is sent to the drive source of the shaft 13, the lid 12 is opened, and the mixed powder in the mixing tank 1 is discharged and supplied to the hopper 14.

As described above, the mixture mixed in the mixing tank 1 is immediately sent to the kneader 6 mainly by its own weight, thereby minimizing the separation between the used paper fine powder and the resin powder, which have significantly different specific gravities. Can be. On the other hand, when the mixture obtained as described above is transported in a long distance or in another container, the waste paper fine powder and the resin powder are separated due to a difference in specific gravity due to vibration or the like at that time. No such separation occurs substantially. The mixture supplied into the hopper 14 is granulated by a conventionally known resin granulator such as the extruder 6.

The resin supplied to the extruder 6 melts the resin by heating and is further mixed with the fine powder of waste paper. By this heating, the water contained in the fine powder of waste paper turns into steam, and the mixture is kneaded as it is. When the granulation is performed, a large number of air bubbles are present in the obtained pellet, which has a great adverse effect on the physical properties of the molded product to be formed later. In the present invention, the extruder 6
, The melting temperature of the resin is set to about 5 to 10 ° C. lower than the conventional granulation temperature of the prior art, and the cylinder of the extruder 6 is preferably provided with two or more exhaust ports. By doing so, the water adsorbed on the used paper fine powder was successfully removed. The preferred granulation temperature is about 130 when the resin is polyethylene.
It is preferable that the temperature of the mixture is in the range of about 40 to 60 seconds.
If the granulation temperature and the residence time in the cylinder are high or long, the fine powder of waste paper may be scorched.

In the prior art, the strand extruded from the nosul of the extruder 6 is water-cooled and then pelletized by a pelletizer. In the present invention, the extruded strand is cooled by air cooling and then pelletized by a pelletizer. Is done. If the extruded strand is cooled by water cooling in the present invention, the fine powder of waste paper in the extruded mixture absorbs water and cannot be formed into a film even if it is later formed into a film.

As shown in the process diagram of FIG. 1, the pelletized resin composition is used as a waste paper master batch. In the present invention, when the whole is 100 parts by weight, the amount of the fine waste paper To 70% by weight, preferably up to about 60% by weight. In order to form a film or other material using such a waste paper master batch, a required amount of natural resin pellets are mixed and diluted with the waste paper master batch to obtain various molded articles having various waste paper contents. Can be. Incidentally, the resin composition of the present invention,
Other additives such as a coloring agent, an antioxidant, an antistatic agent, and other fillers can be included as long as the object of the present invention is not attained.

[0018]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following, "parts" and "%" are based on weight unless otherwise specified. Example 1 A waste paper master batch was obtained as follows using the apparatus shown in FIGS. The resin powder used was a low-density polyethylene with a 40 mesh pass, and the used paper fine powder was obtained by crushing with a Murata Co., Ltd. matcha crusher Super Cyclone and vibrating a 100-mesh sieve in the horizontal direction. It is a fine powder of 100 mesh pass. The waste paper fine powder hardly contains fibers having a length of 0.1 mm or more. The mixing tank used had a capacity of 450 kg, and the rotation speed of the stirring blade was variable to 15 to 30 rpm.
It is.

The above resin powder (100 parts) and used paper fine powder (10)
0 parts from each inlet, and after mixing for about 3 to 5 minutes, the outlet at the bottom of the U-shape is opened, and the discharged mixture is supplied to the hopper 14 of the extruder by a conveying screw, A resin composition having a content of used paper fine powder of 50% by weight, which is melt-kneaded at a cylinder temperature of 130 to 150 ° C. by an extruder provided with three steam exhaust ports at the upper part of the cylinder, air-cooled and pelletized by a pelletizer. I got To this waste paper masterbatch, natural low-density polyethylene pellets are added and mixed in such a ratio that the total waste paper concentration becomes 4% (30% by volume), and then the resin composition is blown with an inflation device (40 m / m extruder, inner diameter The mixture was put into a 50 m / m inflation die, a cylinder temperature of 140 ° C., and a screw rotation speed of 60 rpm) to obtain a light gray polyethylene film having a thickness of 30 μm. The surface of the film was smooth, the fine powder of the used paper was well dispersed, and almost no fine powder of the used paper was recognized by the naked eye, no bubbles were contained, and the strength was sufficient.

Comparative Example 1 A film was produced in the same manner as in Example 1 except that the fine powder of waste paper was sieved with the same mesh and vibrated in the vertical direction. In the obtained film, lump of waste paper fine powder was found everywhere, and the strength of the portion was low and the film was easily torn. Example 2 In Example 1, the waste paper concentration of the waste paper master batch was adjusted to 60.
%, And the concentration of waste paper in the film was set to 5% (40% by volume), and the same result as in Example 1 was obtained.

Comparative Example 2 An attempt was made to produce a film in the same manner as in Example 1 except that a kneader having no steam exhaust port was used as the kneader, but no film could be formed. . Comparative Example 3 A film was produced in the same manner as in Example 1 except that the extruded strand was water-cooled and then pelletized. However, the film could not be formed into a film. Comparative Example 4 A film was produced in the same manner as in Example 1 except that the stirring blade in the mixing tank was replaced with a stirring device that rotated horizontally.

Example 3 Instead of the low-density polyethylene in Example 1, high-density polyethylene, polystyrene, polypropylene or polyester was used, and the kneading temperature was about 5 to 10 ° C. higher than the temperature conventionally used for each resin. Various resin films were obtained in the same manner as in Example 1 except that the lowering was performed. As in Example 1, the surface of these films was smooth, the fine powder of waste paper was well dispersed, almost no fine powder of waste paper was observed with the naked eye, no bubbles were contained, and the strength in the vertical and horizontal directions was sufficient. Also, the welding sealability was sufficient.

[0023]

According to the present invention as described above, it is possible to obtain a resin composition and a molded product in which the used paper fine powder is uniformly dispersed in the resin.

[Brief description of the drawings]

FIG. 1 illustrates a method of the present invention.

FIG. 2 is a diagram illustrating an apparatus of the present invention.

FIG. 3 is a diagram illustrating an apparatus of the present invention.

[Explanation of symbols]

 1: Mixing tank 2: Stirrer blade 3: Bottom 4: Discharge port 5: Supply path 6: Kneader 7: Screw 8: Chute 9: Waste paper fine powder input port 10: Resin powder input port 11: Rotating shaft 12: Cover 13 ： Rotating shaft 14 ： Hopper

Claims (9)

(57) [Claims] 1. A method for producing a waste paper-containing resin composition by mixing waste paper fine powder and resin powder, the step of removing long fibers in the waste paper fine powder, and mixing waste paper fine powder and resin powder. Step, a step of kneading the obtained mixture, a step of granulating the kneaded resin composition, in the mixing step, the used paper fine powder and the resin powder are mixed for a predetermined time by a stirring blade rotating in the vertical direction to obtain Discharging the mixed mixture intermittently from the bottom of the mixing tank, continuously supplying the discharged mixture to a kneader, and removing water from at least two exhaust ports provided in the kneader while kneading. A method for producing a waste paper-containing resin composition, comprising: 2. The method for producing a waste paper-containing resin composition according to claim 1, wherein the long fibers in the waste paper fine powder are removed by a sieve vibrating in a horizontal direction. 3. The method for producing a waste paper-containing resin composition according to claim 1, wherein the length of the long fiber to be removed is 0.1 mm or more. 4. The method for producing a waste paper-containing resin composition according to claim 1, wherein the mixture is discharged from the mixing tank by its own weight. 5. The method for producing a used paper-containing resin composition according to claim 1, wherein the resin powder is a powder of polyethylene, polypropylene or polyester. 6. A mixing tank, a vertically rotating stirring blade provided in the mixing tank, a mixture outlet provided at the bottom of the mixing tank, and a supply for supplying the discharged mixture to a kneader. The bottom of the mixing tank is formed in a substantially U-shape close to the rotation locus of the stirring blade rotating in the vertical direction, and a discharge port for the mixture is provided near the lowest point of the bottom. A mixing device wherein the discharge port is opened intermittently and the mixture falls by its own weight. 7. The mixing device according to claim 6, wherein the mixture is provided with at least two discharge ports. 8. The mixing device according to claim 6, wherein the discharge port of the mixture is intermittently opened in conjunction with the amount of the mixture in the hopper of the kneading machine. 9. The kneader is a screw type extruder,
7. The mixing device according to claim 6, wherein at least two exhaust ports are provided at the upper part of the cinder of the extruder.