JP2024037315A - Molding machine for molded articles of thermoplastic resin composition, and method for producing molded articles - Google Patents

Abstract

An object of the present invention is to provide a molding machine and the like that can take excellent measures against foreign substances when manufacturing a molded article of a thermoplastic resin composition. [Solution] A molding machine 10 for molded articles of a resin composition, which melts and molds a thermoplastic resin composition, includes a supply port 1 for supplying the thermoplastic resin composition, and a heat supply port 1 supplied from the supply port 1. A melt-kneading section 2 for melt-kneading the plastic resin composition, a discharge section 3 for discharging the thermoplastic resin composition melt-kneaded in the melt-kneading section 2, and a discharging section 3 provided between the melt-kneading section 2 and the discharge section 3. A molding machine 10 for molded products of a resin composition, having a resin reservoir 5 and a plurality of filters 61 to 63 arranged in the resin reservoir 5. [Selection diagram] Figure 1

Description

The present invention relates to a molding machine for molded articles of thermoplastic resin compositions. The present invention also relates to a method of manufacturing a molded article.

Material recycling of thermoplastic resin compositions (plastics) is attracting attention. The present inventors have proposed the following technology that can be applied to recycled resins and the like.

Patent Document 1 is a resin composition molding machine that melts a thermoplastic resin composition and molds it into pellets, and includes a supply port for supplying the thermoplastic resin composition, and a thermoplastic resin supplied from the supply port. a melt-kneading section for melt-kneading the composition; a discharge section for discharging the thermoplastic resin composition melt-kneaded in the melt-kneading section in the form of a strand; and a thermoplastic resin composition in the form of a strand discharged from the discharge section. The present invention discloses a resin composition molding machine that has a pelletizer that pelletizes the resin composition by shredding the resin composition, and further has a resin reservoir section provided between the melt kneading section and the discharge section.

Patent Document 2 discloses a thermoplastic resin composition molding machine that melts and molds a thermoplastic resin composition containing a first thermoplastic resin into a strand shape, and includes a supply port for supplying the thermoplastic resin composition. a melt-kneading section for melt-kneading the thermoplastic resin composition supplied from the supply port; a resin reservoir in which the composite resin composition melt-kneaded in the melt-kneading section remains; and a resin reservoir. and a discharge section that discharges the thermoplastic resin composition retained in a strand shape, and the resin reservoir section has a tapered shape from the melt-kneading section toward the discharge section. There is.

Patent No. 6608306 Patent No. 6914541

"Advanced recycling process for waste plastics based on physical degradation theory and its stability", Aya Tominaga, Hiroshi Sekiguchi, Ryoko Nakano, Shigeru Yao, Eiichi Takatori, Journal of Material Cycles and Waste Management, accepted. "Relationship between the long period and the mechanical properties of recycled polypropylene", Aya Tominaga, Hiroshi Sekiguchi, Ryoko Nakano, Shigeru Yao, and Eiichi Takatori, Nihon Reoroji Gakkaishi, 45(5), 287-290 (2017) "Creation of Advanced Recycle Process to Waste Container and Packaging Plastic - Polypropylene Sorted Recycle Plastic Case-", Nozomi Takenaka, Aya Tominaga, Hiroshi Sekiguchi, Ryoko Nakano, Eiichi Takatori, Shigeru Yao, Nihon Reoroji Gakkaishi, 45(3), 139- 143 (2017) "Thermal Process Dependence of Mechanical Properties and Inner Structure of Pre-consumer Recycled Polypropylene", Aya Tominaga, Hiroshi Sekiguchi, Ryoko Nakano, Shigeru Yao, Eiichi Takatori, Proceedings of PPS-30, AIP Conf.Proc. 1664, 150011-1 - 150011-4, 2015 “Advanced recycling technology for pre-consumer recycled polypropylene”, Aya Tominaga, Hiroshi Sekiguchi, Ryoko Nakano, Shigeru Yao, Eiichi Takatori, Kobunshi Ronsen, 70(12), 712-721 (2013). "Inner structure and mechanical properties of recycled polypropylene. ", Shigeru Yao, Aya Tominaga, Youhei Fujikawa, Hiroshi Sekiguchi, and Eiichi Takatori, Nihon Reoroji Gakkaishi (J. Soc. Rheol, Japan), 41(3), 173-178 ( 2013).

Resin compositions may contain foreign matter, or substances that cause foreign matter may be generated during the melting process. In particular, recycled thermoplastic resin compositions contain a large amount of foreign matter, and therefore have disadvantages such as poor mechanical properties and difficulty in forming into a film due to breakage initiated by foreign matter. Thermoplastic resin compositions recycled by the techniques described in Patent Documents 1 and 2 can also be used to improve physical properties. However, by taking measures against foreign substances, many improvements can be expected, such as improved physical properties, moldability of thin films, and prevention of damage to molding machines and molds during molding.

In order to remove these foreign substances, a filter has conventionally been installed, if necessary, just before the die that serves as the discharge section at the tip of the extruder. If a coarse mesh filter is used for this filter, it will not become clogged and can be discharged for a long time, but foreign matter will not be removed completely and a good product cannot be obtained. On the other hand, when a fine mesh filter is used, it quickly becomes clogged, making stable discharge impossible.

Under such circumstances, an object of the present invention is to provide a molding machine and the like for molded articles of thermoplastic resin compositions that are excellent in foreign matter prevention.

As a result of extensive research in order to solve the above problems, the present inventors found that the following invention met the above objects, leading to the present invention. That is, the present invention relates to the following inventions.

<1> A molding machine for molded products of resin compositions, which melts and molds thermoplastic resin compositions,
a supply port for supplying a thermoplastic resin composition;
a melt kneading section that melts and kneads the thermoplastic resin composition supplied from the supply port;
a discharge section that discharges the thermoplastic resin composition melt-kneaded in the melt-kneading section;
a resin reservoir provided between the melt-kneading section and the discharge section;
A molding machine for molded products of a resin composition, including a plurality of filters arranged in the resin reservoir.
<2> The filters are arranged at a plurality of positions at intervals and have different openings, and the filters are arranged at a plurality of positions at intervals from the melt-kneading section side toward the discharge section side. The molding machine according to <1>, wherein the filters are arranged so that the minimum opening of the filters becomes smaller in order.
<3> The molding machine according to <1> or <2>, wherein the filter is one or more selected from the group consisting of a metal mesh filter, a screen changer, and a laser filter.
<4> A resin composition molding machine that melts and molds a thermoplastic resin composition,
a supply port for supplying a thermoplastic resin composition;
a melt kneading section that melts and kneads the thermoplastic resin composition supplied from the supply port;
a discharge section that discharges the thermoplastic resin composition melt-kneaded in the melt-kneading section;
a resin reservoir provided between the melt-kneading section and the discharge section;
A method for manufacturing a molded article made of a resin composition using a resin composition molding machine having a plurality of filters arranged in the resin reservoir, the method comprising:
supplying the thermoplastic resin composition to the supply port;
Melting and kneading the thermoplastic resin composition in the melt-kneading section;
filtering the thermoplastic resin composition with the filter disposed in the resin reservoir;
and discharging the thermoplastic resin composition from the discharging section.
<5> The method according to <4>, wherein the thermoplastic resin composition is a recycled resin.
<6> The method according to <4> or <5>, wherein the residence time of the thermoplastic resin composition in the resin reservoir is 10 seconds or more and 600 seconds or less.

According to the molding machine and the like of the present invention, excellent measures against foreign substances can be taken when manufacturing molded articles of thermoplastic resin compositions.

1 is a schematic diagram showing an example of a first embodiment of a molding machine according to the present invention. FIG. 2 is a diagram for explaining the outline of a filter used in the molding machine of the present invention. FIG. 2 is a schematic diagram showing an example of a second embodiment of a molding machine according to the present invention. It is a figure showing the DSC analysis result of the sample used in an example. It is an image showing the state of the filter after the test of the example. It is an image showing the state of the filter after the test of the example. It is a figure showing the shape of the test piece which performs the tensile test of an example. This is an image obtained by observing a film produced in an example. It is a figure which shows the result of the tensile test of the film produced in the Example. It is a figure which shows the result of the tensile test of the film produced in the Example. This is an image obtained by observing a film produced in an example. It is a figure which shows the result of the tensile test of the film produced in the Example. It is a figure which shows the result of the tensile test of the film produced in the Example. This is an image obtained by observing a film produced in an example. This is an image obtained by observing a film produced in an example.

The embodiments of the present invention will be described in detail below, but the explanation of the constituent elements described below is an example (representative example) of the embodiments of the present invention, and the present invention will be described below unless the gist thereof is changed. is not limited to the content. Note that when the expression "~" is used in this specification, it is used as an expression including the numerical values before and after it.

[Molding machine of the present invention]
The molding machine of the present invention is a molding machine for molded articles of a resin composition, which melts and molds a thermoplastic resin composition, and includes a supply port for supplying the thermoplastic resin composition; A melt-kneading section for melt-kneading a thermoplastic resin composition, a discharge section for discharging the thermoplastic resin composition melt-kneaded in the melt-kneading section, and a resin provided between the melt-kneading section and the discharge section. The present invention is a molding machine for a molded article of a resin composition, the resin composition having a reservoir section and a plurality of filters disposed in the resin reservoir section.

[Method of the present invention]
The method of the present invention is a method of manufacturing a molded article formed by molding a resin composition using the molding machine of the present invention, the method comprising: supplying the thermoplastic resin composition to the supply port; A step of melt-kneading the thermoplastic resin composition in a kneading section, a step of filtering the thermoplastic resin composition with the filter disposed in the resin reservoir section, and a step of discharging the thermoplastic resin composition from the discharge section. and a step of discharging the object.

In studying the present invention, an extruder without a screw was provided with a resin reservoir where molten resin could stay. Furthermore, by dividing this resin reservoir and increasing the number of positions where filters can be inserted, it is possible to remove foreign substances using multiple filters (multi-filter). This allows you to arrange filters in stages, such as a coarse mesh filter, a medium mesh filter, and a fine mesh filter from the front.

By installing such a multi-filter, it has become possible to remove even the smallest foreign matter without clogging. In addition, this effect has improved the physical properties of molded products, such as no breakage during molding and excellent tensile properties, making it possible to process thin films. Furthermore, fish eyes due to gel-like components were reduced, and the appearance performance was greatly improved.

[Molding machine 10]
FIG. 1 is a schematic diagram showing an example of an embodiment of a molding machine according to the present invention. The molding machine 10 has a supply port 1, a melt-kneading section 2, a discharge section 3, a resin reservoir section 5, and a filter 61, a filter 62, and a filter 63. Further, here, in order to mold pellets as a molded product, the thermoplastic resin composition is extruded into a strand shape, cut by a pelletizer 4, and the pellets are collected into a container 7.

The supply port 1 is a hopper-shaped supply port, and the thermoplastic resin composition is supplied from the upper part of the supply port. The melt-kneading section 2 is a section for melt-kneading the thermoplastic resin composition supplied from the supply port 1. This melt-kneading section 2 is heated to the melting temperature of the thermoplastic resin composition, and by rotating a screw 21 connected to a motor M, the thermoplastic resin composition is extruded toward the resin reservoir section 5 side. Further, when passing between the pipe and the screw, shear stress is applied to the thermoplastic resin composition, and the resin composition is kneaded.

The resin reservoir section 5 is provided between the melt-kneading section 2 and the discharge section 3. This resin reservoir section 5 is set at a temperature that allows the thermoplastic resin to flow, and can eliminate the shear stress applied to the thermoplastic resin composition melt-kneaded in the melt-kneading section 2. The discharge section 3 discharges the thermoplastic resin composition after passing through the resin reservoir section 5 and being melted and kneaded. The pelletizer 4 shreds and pelletizes the strand-shaped thermoplastic resin composition discharged from the discharge section 3. Since the pellets obtained by this molding machine 10 have been subjected to foreign matter removal, etc., when the pellets are subsequently molded into an arbitrary molded product, the physical properties etc. of the pellet can be improved.

[Thermoplastic resin composition]
Thermoplastic resins are resins that soften when heated and can be extruded or injection molded. The thermoplastic resin composition is a composition made of a thermoplastic resin molded by a melt extrusion method and additives appropriately mixed. Specific examples of this thermoplastic resin include polyolefin resins, polystyrene (PS), acrylonitrile-butadiene-styrene copolymers (ABS resins), acrylic resins such as PMMA, polyvinyl chloride, and polyamide resins. , polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polycarbonate (PC), polyether ether ketone (PEEK), polyphenyl sulfide (PPS), and the like.

It is preferable that the thermoplastic resin of the present invention contains polyolefin. Polyolefin is a crystalline polymer obtained by polymerizing an α-olefin having a double bond at the 1-position, such as polyethylene and polypropylene. In the present invention, recycled polyolefins can be used. Recycled polyolefin refers to pre-consumer products such as waste and defective products generated in the process of forming molded products from virgin product pellets, and recycled plastics in containers and packaging (so-called It is a general term for polyolefins that are recovered as waste plastics such as ``Yonrepla''.

These thermoplastic resin compositions can be recycled resins. Thermoplastic resin compositions may be obtained through recycling and thus collected as solids. Alternatively, if the molded product to be recycled uses a plurality of polyolefins, the resin recycled from the molded product is recovered as a thermoplastic resin composition containing the plurality of recycled polyolefins from the beginning. In addition, other substances that may be mixed in during the recycling process, such as paper, pigments, wood chips, metal chips, adhesives, inorganic powders, inorganic fillers, and polystyrene-derived materials, may be attached to products or mixed in during the recovery process. , 1,4-added butadiene units and polyethylene terephthalate, or other plastics, are also collected as a mixed solid at room temperature.

The thermoplastic resin composition may consist essentially of a thermoplastic resin. In addition, it may contain impurities that are generally included in thermoplastic resin compositions. Moreover, it may contain various additives and the like, which are used in combination with the thermoplastic resin composition. As additives, various physical property improvers can be used, such as colorants, stabilizers, UV absorbers, plasticizers, and the like. The first thermoplastic resin contained in the thermoplastic resin composition is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. There is no particular upper limit to the amount of the first thermoplastic resin contained in the thermoplastic resin composition, but since it may contain additives and small amounts of impurities, it may be 99.9% by mass or less, or 99.5% by mass. % or less, 99% by mass or less, 98% by mass or less, or 95% by mass or less.

The thermoplastic resin composition containing recycled products such as recycled polyolefin can be made into pellets in advance by appropriately pulverizing the composition or by melting and kneading the mixture using a common pelleter. These pellets or pulverized solids can be used as a thermoplastic resin composition for producing molded articles of the thermoplastic resin composition of the present invention so that they can be supplied to the supply port of the present invention. can.

[Supply port 1]
The supply port 1 is a part that supplies the thermoplastic resin composition. The supply port 1 may be one used in a general molding machine or the like, and a hopper having a conical portion or a pyramidal diameter portion may be used.

[Melt kneading section 2]
The melt-kneading section 2 is a section that melt-kneads the thermoplastic resin composition supplied from the supply port. The melt-kneading section 2 uses a screw or the like provided with a plurality of sections of different shapes, such as a feed section, a kneading section, and a conveyance section, to perform melting and kneading, taking extrusion temperature, pressure, conveyance properties, etc. into consideration as appropriate. It is heated to a certain temperature and transported.

[Discharge part 3]
The discharge section 3 is a section that discharges the thermoplastic resin composition melt-kneaded in the melt-kneading section 2. The molding machine 10 is an example of molding pellets, and the discharge section 3 is a part that extrudes pellets into a strand shape. After extruding into a strand, the pellets are cut by a pelletizer 4 and collected into a container 7.

Although the molding machine 10 is used for molding pellets, it may be used for molding other thermoplastic resins. For example, the discharge portion 3 may be adapted to various shapes of molded articles of thermoplastic resin compositions. For example, it may be extruded into a cylindrical shape, a film shape, a plate shape, a U-shape, an L-shape, a T-shape, or various other irregular shapes. It may also be used for T-die, inflation, injection molding, etc.

[Resin reservoir part 5]
The resin reservoir portion 5 is a portion provided between the melt-kneading portion 2 and the discharge portion 3. The resin reservoir portion 5 is a hollow portion in which the screw 21 is not provided. The resin reservoir section 5 is connected to the melt-kneading section 2 through a connecting section 501. Further, the resin reservoir portion 5 is connected to the discharge portion 3 through a connecting portion 502. The resin reservoir can be achieved, for example, by connecting a pipe that extends in the same cross-section as the pipe of the melt-kneading part between the melt-kneading part and the discharge part of a general pelletizing device. can. This stretched piping portion becomes a resin pool where kneading by the screw 21 is not performed.

The resin reservoir portion 5 may be divided by a filter. The molding machine 10 is separated into three chambers, a resin reservoir 51, a resin reservoir 52, and a resin reservoir 53, by a filter 61, a filter 62, and a filter 63. The resin reservoirs 51 to 53 can each have a shape that allows the resin to remain there for a time that allows the shear to be resolved. Although the molding machine 10 has three chambers, the multi-filter used in the molding machine of the present invention is, for example, one in which the resin reservoir can be divided into 2 to 7 chambers, 3 to 5 chambers, and filters can be placed in each chamber. You may.

Like the resin reservoirs 51 to 53, the length of each chamber that becomes the resin reservoir 5 can be, for example, 10 mm or more, 20 mm or more, 30 mm or more, 50 mm or more, 100 mm or more. Further, the total length of the entire resin reservoir portion 5 may be 20 mm or more, 30 mm or more, 50 mm or more, 100 mm or more, 200 mm or more, etc. The upper limit can be set as appropriate depending on the size of the molding machine 10, the melting rate, etc., and can be set to 1000 mm or less, 800 mm or less, 500 mm or less, etc.

[Residence time]
The residence time of the thermoplastic resin composition in the resin reservoir 5 can be appropriately set according to the size of the molding machine, the resin, and the like. For example, the residence time can be 10 seconds or more and 600 seconds or less. Note that the residence time in the resin reservoir is the total residence time in each of the plurality of separated chambers. Generally, in a pelletizing device, the amount of extrusion per unit time is controlled within a predetermined range depending on the type of thermoplastic resin composition and the capacity of the pelletizing device. Based on this extrusion amount, the volume of the resin reservoir is adjusted.

More specifically, it is preferable that the size of this resin reservoir is such that the residence time can be set to 10 to 300 seconds. Further, the resin reservoir can have a volume that achieves the residence time. This residence time is determined from the amount of extrusion divided by the volume of the resin reservoir.

Note that this residence time may be determined from the length of the screw corresponding to the melt-kneading section, and if the screw is shortened with respect to the piping up to the discharge section, the length of the screw up to the position where the screw is installed is It is considered a melt-kneading section because a large amount of shear is applied between it and the piping. On the other hand, since kneading by the screw is not performed in a pipe without a screw, this volume can be regarded as a resin reservoir and its residence time etc. can be managed.

This residence time is more preferably 30 seconds or more, and even more preferably 60 seconds or more. The longer the residence time is, the more the molding history due to shearing history can be eliminated, and a resin composition with more restored initial physical properties can be obtained. On the other hand, the upper limit is preferably 240 seconds or less. The effect of eliminating molding history due to shear history by increasing the residence time becomes less effective after a certain value, so there is little need to increase the residence time beyond a certain value in terms of device design.

When designing this residence time as a volume, it can be designed so that the minimum residence time can be achieved based on the maximum extrusion rate of the extrusion molding machine. Alternatively, since the residence time can be substantially controlled by the length of the pipe installed as the resin reservoir 5, the design may be such that the length can be changed as appropriate depending on the operating conditions.

[Filters 61 to 63]
The resin reservoir has a plurality of filters arranged therein. Moreover, it is preferable to have filters arranged at a plurality of positions at intervals. In the molding machine 10, a resin reservoir 51 is formed between the filter 61 and the filter 62 by a distance L1. Further, the filter 62 and the filter 63 are spaced apart by a distance L2 to form a resin reservoir portion 52.

By arranging the filters apart, a resin reservoir is provided between each filter, and the resin reservoir can eliminate the shear history when passing through the filter, dispersing the pressure applied when passing through the filter, and preventing the accumulation of foreign matter. It can be made into a department. In addition, fibrous foreign matter that once passed through the filter in a form that was oriented along the flow, is retained and the orientation is relaxed, so that it can be removed by the next filter.

It is preferable to use a plurality of filters with different openings. It is preferable that these filters are arranged such that the minimum opening of the filters arranged at a plurality of positions becomes smaller in order from the melt-kneading section side toward the discharge section side. That is, it is preferable to gradually reduce the opening.

By gradually decreasing the opening, large foreign substances are filtered toward the front side of the resin flow direction of the molding machine 10, and small foreign substances are filtered toward the rear side. This prevents the filter from clogging, efficiently removes foreign matter, and allows stable operation for long periods of time.

Preferably, the filter is a combination of a main filter and a support member in contact with each other. In particular, if a filter with a small opening is used, it is possible that the filter may not be able to withstand the pressure and be damaged, or that the flow may become uneven due to slight clogging. For this purpose, a filter with a small opening serving as the main filter is used in contact with a filter having a different opening, thereby serving as a supporting member.

Also, the filter can be used in combination with a breaker plate. FIG. 2 shows an example of the main filter 611 and the breaker plate 612.

Such a filter is used as the filter 61, for example, with a mesh opening of about 130 μm to 250 μm. Next, as the filter 62, one with an opening of about 80 μm to 180 μm is used. As the filter 63, one with an opening of about 50 μm to 100 μm is used. As a result, it is preferable that the opening becomes smaller in stages. In addition, when a plurality of filters are stacked and used as a filter for each chamber, a filter with a small opening is used as the opening of the filter for that chamber.

As the filter, a metal mesh made of stainless steel or the like having heat resistance, pressure resistance, etc., a laser filter, or the like can be used so that the molten resin can be filtered even if it passes through.

[Forming machine 11]
FIG. 3 shows a second embodiment of the molding machine of the present invention. In addition to the molding machine 10 of the first embodiment, the molding machine 11 further includes a quenching section 8.

The quenching section 8 can be, for example, a water tank filled with water or ice water. The thermoplastic resin composition discharged from the discharge section 3 can be continuously flowed into this water tank in the form of a strand. In addition, since the thermoplastic resin composition discharged from the discharge section has a relatively high temperature, the temperature of the refrigerant in the quenching section 8 may easily rise. By providing a refrigerant and continuously supplying refrigerant into this piping, the heat balance may be balanced and stable operation may be performed.

The medium that comes into contact with the molten resin composition for rapid cooling may be a gas, a solid, or the like, but it is preferable to use a liquid. The most preferable medium is one mainly composed of water from the viewpoint of heat capacity and stability. Further, the temperature is more preferably 0°C to 20°C, or 0°C to 10°C. Note that the final thermoplastic resin composition is obtained by removing the resin after quenching with a liquid such as water by appropriately wiping or drying the liquid.

The method of the present invention includes the step of supplying a thermoplastic resin composition to a supply port using the molding machine according to the present invention. Next, there is a step of melt-kneading the thermoplastic resin composition in a melt-kneading section. Next, there is a step of filtering the thermoplastic resin composition using a filter placed in the resin reservoir. and a step of discharging the thermoplastic resin composition from the discharging section. Furthermore, the thermoplastic resin composition after being discharged is appropriately molded to match the shape of the molded article.

According to the present invention, even if the thermoplastic resin composition contains foreign matter or generates foreign matter due to melt-kneading, these foreign matter can be removed and a molded article with good properties can be molded. This makes it possible to prevent defects caused by foreign matter. For example, it is possible to obtain products with excellent optical properties and mechanical properties. In addition, it can be operated stably even for long periods of time.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is changed.

1. Molding Machine Pellets were manufactured using a molding machine having a configuration similar to the molding machine shown in FIG. 3. The main equipment conditions will be described later.

(1) Extruder Pelletization was performed using a twin-screw kneading extruder with a diameter of 26 mm and L/D=60 manufactured by Plastic Engineering Research Institute Co., Ltd., which is installed within Fukuoka University. The main experimental conditions are as follows, and the specific experimental conditions will be described later.

(2) Resin reservoir Three cylindrical parts (resin reservoirs 51 to 53) each having a diameter of 38 mm and a length of 120 mm were incorporated into the extruder. In addition, breaker plates and mesh were installed between the cylindrical parts. At this time, the total length of the resin reservoir is 360 mm, the volume of the resin reservoir is 0.41 L, and the density of the molten resin is 0.77 kg/L. When the feeder is 10 kg/h, the resin reservoir residence time is: The time is determined to be 114 seconds using the calculation formula: (volume of resin reservoir) x (density of molten resin) ÷ (supply amount)).

(3) Filter A stainless steel mesh filter with a shape (circular) matching the diameter of the resin reservoir as shown below was used. 100 mesh (opening approximately 154 μm), 150 mesh (opening 109 μm), 200 mesh (opening 77 μm).

・Filter arrangement The following mesh filters were arranged at each stage along the flow direction of the resin reservoir. In addition, from the melt-kneading part side toward the discharge part side, they are called the first stage, the second stage, and the third stage.
Filter conditions (1) 1st stage 100 mesh, 2nd stage 150 mesh, 3rd stage 200 mesh Filter conditions (2) 1st stage 100 mesh and 150 mesh, 2nd stage 150 mesh and 60 mesh, 3rd stage 200 mesh and 60 mesh

(4) Water tank A water tank was provided at the location where the strands discharged from the discharge section flowed. The melted and discharged strands are cooled and solidified by this water tank. While the extrusion experiment was being conducted, the water temperature was measured and confirmed to be within the range of 10-28°C.

(5) Pelletizer A pelletizer (pelletizer 4 in FIG. 1) was provided to shred the strand discharged from the discharge section of the extruder into pellets having a length of about 3 mm.

2. Sample The following was used as a sample to be molded.
- Sample (1) "PEmix": PE mix (trade name) (MFR 0.7 (g/10 minutes)), which is a container and packaging recycled resin whose polyethylene components have been sorted, manufactured by Toyama Kankyoku Kyoui Co., Ltd., was used.
・Sample (2) "PP mix": PP mix (product name), which is a mixture of recycled PP from hard container and packaging plastics and soft container and packaging plastics, manufactured by Toyama Environmental Services Co., Ltd. (MFR 6.35 (g) Figure 4 is a diagram showing the DSC analysis results of the samples used in the examples.When the melting points of the samples were measured by DSC, a peak of PE was observed at 125°C and a peak of PP was observed at 161°C. Furthermore, when the ratio of PE to PP was calculated based on the heat of fusion, it was found that PE:PP≈8:92.

[Manufacture example 1 (pelletization)]
A recycled resin sample was pelletized using the molding machine described above.

[Production example (1-1)] PEmix
Pellets were manufactured using PEmix of sample (1). The filter for the molding machine used was one that met filter condition (1). The operating conditions of the molding machine are as shown in the table below.

[Production example (1-2)] PPmix
Pellets were manufactured using the PP mix of sample (2). The filter for the molding machine used was one that met filter condition (1). The operating conditions of the molding machine are as shown in Table 2 below.

[Production example (1-3)] PPmix
Pellets were manufactured using the PP mix of sample (2). As the filter for the molding machine, a filter with filter condition (2) was used instead of production example (1-2). The operating conditions of the molding machine are as shown in Table 2.

Multi-mesh extrusion was performed using a twin-screw extruder. Figures 5 and 6 show the appearance of the mesh taken out after extrusion.
- In filter condition (1) of manufacturing example (1-2), foreign matter was concentrated on the edge of the filter, and the area where the filter was torn was large. FIG. 5 is an image showing this state of the filter of the example after testing.
- Filter condition (2) in manufacturing example (1-3) was a combination of filters, and the entire filter was covered with foreign matter, making effective use of the entire filter. FIG. 6 is an image showing the state of the filter after the test of the example.

[Production Example 2] Film Formation Test Using the pellets produced in Production Example 1, a film was formed and evaluated.
The film was formed by press molding or by using a film-forming device. In addition, appearance, film formability, tensile test, etc. were evaluated.

[Press molding]
A film was produced by pressing at a temperature of 180° C., a gauge pressure of 25 MPa (actual pressure 1.8 MPa), a pressing time of 2 minutes, a thickness of 0.1 mm, and slow cooling. The press molding machine used was Yours Giken's "HMM-10HP-A".

[Forming using film forming equipment]
In order to compare the film forming ability of the original PP mix and the PP mix subjected to multi-mesh extrusion, a study was conducted using Labo Plast Mill (registered trademark) (Toyo Seiki Seisakusho, small twin-screw segment extruder 2D15W). Under extrusion conditions of a melt-kneading temperature of 200° C. and a motor rotation speed of 30 rpm, the pellets obtained in Sample (2) or Production Example (1-2) are fed from a feeder, and the film is taken off by a take-off machine. The feeder rotation speed [rpm] is lowered and the take-up speed [m/min] is increased to make the film thinner, and it is stopped when the film formation becomes difficult (the film is torn and cannot be recovered). Table 3 shows the experimental conditions.

[Tensile test]
The press-formed film produced in Production Example 2 was punched out into a dumbbell shape according to the 1/3 reduced size of Type 5 of JIS K7127 (1999) and used as a sample for the tensile test. Figure 7 shows the details of the tensile test piece and the test piece.
A tensile test was performed on the sample using a tensile tester (Tokyo Shikenki Co., Ltd. "LSC-02/30-20"). The conditions for the tensile test were: distance between grips 40 mm, temperature 25°C, humidity 50%. Each pellet produced in Production Example 1 was tested seven times, and Young's Modulus was determined based on the stress-strain curve of each test. ) and fracture elongation were measured, and the area of the stress-strain curve until fracture was calculated as elongation fracture energy (toughness). However, the average of 5 times excluding the minimum value and maximum value was used as data. Note that the tensile speed was 10.0 mm/min for PEmix and 5.0 mm/min for PPmix.

[Production example (2-1)] PEmix
Using the pellets of Production Example (1-1), a film was produced by press molding and evaluated.

- Appearance Figure 8 is an image of the film produced in the example. (a) is a film that is the raw material of PEmix (original). (b) is a film of pellets under condition (1) of Production Example (1-1). (c) is a film of pellets under condition (2) of Production Example (1-1). (d) is a film of pellets under condition (3) of Production Example (1-1). (e) is a film of pellets under condition (4) of Production Example (1-1). In both images, the observed foreign matter is circled to emphasize it. It was confirmed that foreign matter was reduced in all cases compared to the original PEmix (a in the figure). Further, it is thought that there is no change due to repelletizing conditions such as temperature and rotation speed.

-Tensile Test FIGS. 9 and 10 are diagrams showing the results of a tensile test of the films produced in Examples. FIG. 9 shows the elongation fracture energy of each film molded product calculated from the stress-strain curve. FIG. 10 shows Young's modulus.

Comparing the original product and the product with foreign matter removed in terms of elongation fracture energy and Young's modulus, removal of foreign matter by multi-mesh extrusion improved the elongation fracture energy, and the physical properties increased under conditions of higher temperature and rotation speed. It was confirmed that there is. On the other hand, Young's modulus was not confirmed to be significantly different from the original product, but it was confirmed that the Young's modulus increased slightly as the rotation speed increased. Based on these results, it is considered that foreign matter removal and resin accumulation treatment are effective in restoring the mechanical properties of PEmix pellet molded products.

[Production example (2-2)] PPmix
Using the pellets of Production Example (1-2), a film was produced using a press molding and film forming apparatus and evaluated.

- Appearance FIG. 11 is an image of the film produced in the example. There were clearly fewer foreign substances under the conditions of production example (1-2) in which repelletization was performed than in the original PPmix.

-Tensile Test FIGS. 12 and 13 are diagrams showing the results of a tensile test of the films produced in Examples. FIG. 12 shows the elongation at break obtained from the stress-strain curve. FIG. 13 shows Young's modulus.

Condition (A) of Production Example (1-2) improved the elongation at break by about 36 times compared to the original. It was confirmed that foreign matter was particularly removed under these conditions, and it is thought that the removal of foreign matter by the mesh had an effect on improving the elongation at break.

-Film forming ability evaluation results using Labo Plastomill (registered trademark) The results of film forming ability evaluation using Labo Plastomil (registered trademark) are shown. FIG. 14 is an observed image of sample (2) "PPmix" made into a film without removing foreign matter. FIG. 15 is an image of the film produced under pelletizing conditions (A) of Production Example (1-2). Condition (a) of Production Example (1-2) made it possible to obtain a thinner film than the original. Since the original was torn at the foreign object, it is thought that the film could be made thinner by removing the foreign object.

・Operating time Through production examples (1-1) and (1-2) of the present invention, pelletization was performed using a device equipped with a 200 mesh filter, and it was operated for 6 hours and more than 30 kg of resin was extruded. There was no increase in resin pressure due to filter clogging, and stable pelletization was possible.

INDUSTRIAL APPLICATION This invention can be utilized for molding a thermoplastic resin composition, and is industrially useful.

1 Supply port 10, 11 Molding machine 2 Melt-kneading section 21 Screw 3 Discharge section 4 Pelletizer 5, 51, 52, 53 Resin reservoir section 61-63 Filter 611 Main filter 612 Breaker plate 7 Container 8 Quenching section

Claims (6)

A molding machine for molding a resin composition by melting and molding a thermoplastic resin composition,
a supply port for supplying a thermoplastic resin composition;
a melt kneading section that melts and kneads the thermoplastic resin composition supplied from the supply port;
a discharge section that discharges the thermoplastic resin composition melt-kneaded in the melt-kneading section;
a resin reservoir provided between the melt-kneading section and the discharge section;
A molding machine for molded products of a resin composition, including a plurality of filters arranged in the resin reservoir. The filter is arranged at a plurality of positions at intervals, and uses a plurality of filters with different openings,
The molding according to claim 1, wherein the filters arranged at the plurality of positions are arranged so that the minimum opening of the filters becomes smaller in order from the melt-kneading section side toward the discharge section side. Machine. The molding machine according to claim 2, wherein the filter is one or more selected from the group consisting of a metal mesh filter, a screen changer, and a laser filter. A resin composition molding machine that melts and molds a thermoplastic resin composition,
a supply port for supplying a thermoplastic resin composition;
a melt kneading section that melts and kneads the thermoplastic resin composition supplied from the supply port;
a discharge section that discharges the thermoplastic resin composition melt-kneaded in the melt-kneading section;
a resin reservoir provided between the melt-kneading section and the discharge section;
A method for manufacturing a molded article made of a resin composition using a resin composition molding machine having a plurality of filters arranged in the resin reservoir, the method comprising:
supplying the thermoplastic resin composition to the supply port;
Melting and kneading the thermoplastic resin composition in the melt-kneading section;
filtering the thermoplastic resin composition with the filter disposed in the resin reservoir;
and discharging the thermoplastic resin composition from the discharging section. 5. The method of claim 4, wherein the thermoplastic resin composition is a recycled resin. The method according to claim 4, wherein the residence time of the thermoplastic resin composition in the resin reservoir is 10 seconds or more and 600 seconds or less.