Method for producing sheet-like extrusion molded product

Abstract

The present disclosure addresses the problem of providing a method which is for producing a sheet-like extrusion molded product and with which it is possible to suppress wear on an extrusion molding machine, improve the moldability of a thermoplastic resin composition, and produce a sheet-like extrusion molded product having a small linear expansion coefficient. The method for producing a sheet-like extrusion molded product involves kneading a thermoplastic resin composition and then extrusion-molding the same through a dye. The thermoplastic resin composition contains a thermoplastic resin and a filler. The thermoplastic resin comprises a polypropylene having an MFR of 20 g / 10 min to 60 g / 10 min at a temperature of 230 °C and a load of 2.16 kgf. The filler comprises wood flour and talc. The content of the filler is 60 parts by mass to 72 parts by mass with respect to 100 parts by mass of the total of the thermoplastic resin and the filler. The content of the wood flour is 20 parts by mass to 70 parts by mass with respect to 100 parts by mass of the total filler.

Description

Manufacturing method for sheet-shaped extrusion molding

[0001] The present disclosure relates to a method for producing a sheet-like extrusion molded product.

[0002] Patent Document 1 discloses an inorganic filler-containing resin composition. This inorganic filler-containing resin composition contains a thermoplastic resin and an inorganic filler. Furthermore, wood flour is mixed into the inorganic filler-containing resin composition. The content of the inorganic filler is 40 mass% or more based on the total amount of the inorganic filler-containing resin composition.

[0003] When the inorganic filler-containing resin composition of Patent Document 1 is used in an extrusion molding method, there is a problem that the extruder is easily worn. Furthermore, if an attempt is made to suppress the wear of the extruder by revising the composition of the inorganic filler-containing resin composition, there is a risk that the moldability of the inorganic filler-containing resin composition will decrease or the linear expansion coefficient of the molded product will increase.

[0004] Japanese Patent Application Laid-Open No. 2004-203982

[0005] An object of the present disclosure is to provide a method for producing a sheet-like extrusion molded product that suppresses wear on an extruder, improves the moldability of a thermoplastic resin composition, and enables the production of a sheet-like extrusion molded product with a small linear expansion coefficient.

[0006] In a method for producing a sheet-like extrusion molded product according to one embodiment of the present disclosure, a thermoplastic resin composition is kneaded and then extruded through a mold. The thermoplastic resin composition contains a thermoplastic resin and a filler. The thermoplastic resin includes polypropylene having an MFR of 20 g / 10 min or more and 60 g / 10 min or less at a temperature of 230°C and a load of 2.16 kgf. The filler includes wood flour and talc. The content of the filler is 60 parts by mass or more and 72 parts by mass or less, based on 100 parts by mass of the total of the thermoplastic resin and the filler. The content of the wood flour is 20 parts by mass or more and 70 parts by mass or less, based on 100 parts by mass of the total of the filler.

[0007] 1. Overview Generally, when using the extrusion molding method, an extrusion molding machine is used. The extrusion molding machine includes, for example, an extruder, a gear pump, a mold, a cooling machine, a take-up machine, and a cutting machine.

[0008] Examples of the extruder include a single-screw extruder having one screw and a twin-screw extruder having two screws. Twin-screw extruders include co-rotating twin-screw extruders and counter-rotating twin-screw extruders.

[0009] The gear pump is placed between the extruder and the mold and uses the meshing parts of gears to transfer the molten resin from the extruder to the mold.

[0010] Specifically, the mold is a die. The die is a nozzle attached to a gear pump. In this embodiment, for example, a T-die (hanger die) is used. This allows the molten resin to be extruded into a sheet shape.

[0011] The cooler cools and solidifies the resin extruded into a sheet shape. In this embodiment, for example, a three-roll cooling roll is used.

[0012] The take-up machine takes up the solidified, long sheet-like extrusion molding. At this time, the surface of the sheet-like extrusion molding may be subjected to a corona treatment, and then a decorative sheet may be attached. Examples of decorative sheets include those printed with a wood grain pattern or a stone grain pattern.

[0013] The cutter cuts the long sheet-like extrusion molded product (including those with decorative sheets attached) into a predetermined length. The sheet-like extrusion molded product thus obtained is used, for example, as flooring material.

[0014] When the inorganic filler-containing resin composition of Patent Document 1 is used to produce a sheet-like extrusion molded product, there is a risk of wear on the screw of the extruder or the gear of the gear pump. Wear on the extruder makes it difficult to stably produce a sheet-like extrusion molded product, so parts such as the screw and gear must be replaced periodically every few months to every six months. This increases running costs, such as maintenance costs.

[0015] Therefore, the present inventors investigated the causes of wear in the extruder in order to suppress the wear, and as a result, they came to the conclusion that one of the causes of wear in the inorganic filler-containing resin composition of Patent Document 1 is the high content of inorganic filler (particularly mica).

[0016] However, since the inorganic filler is necessary to ensure the strength of the sheet-shaped extrusion molded product, it is not sufficient to simply reduce the content of the inorganic filler, because reducing the content of the inorganic filler may affect the moldability and the linear expansion coefficient of the sheet-shaped extrusion molded product.

[0017] In light of the above, the present inventors have developed the following method for producing a sheet-like extrusion molded product. That is, in the method for producing a sheet-like extrusion molded product according to this embodiment, a thermoplastic resin composition is kneaded and then extruded through a mold. The thermoplastic resin composition contains a thermoplastic resin and a filler.

[0018] Here, the thermoplastic resin includes polypropylene having an MFR of 20 g / 10 min or more and 60 g / 10 min or less at a temperature of 230° C. and a load of 2.16 kgf.

[0019] The filler contains wood flour and talc, and the content of the filler is 60 parts by mass or more and 72 parts by mass or less relative to 100 parts by mass of the thermoplastic resin and the filler combined. The content of the wood flour is 20 parts by mass or more and 70 parts by mass or less relative to 100 parts by mass of the filler combined.

[0020] As will be described in detail later, by satisfying the above requirements, it is possible to suppress wear on the extruder, improve the moldability of the thermoplastic resin composition, and produce a sheet-shaped extrusion molded product with a small linear expansion coefficient.

[0021] 2. Details The method for producing a sheet-like extrusion molded product according to this embodiment will be described below.

[0022] The sheet-shaped extrusion molded product according to this embodiment is produced by extrusion molding, and when extrusion molding is used, a known extruder can be used.

[0023] That is, in the method for producing a sheet-like extrusion molded product according to this embodiment, for example, the thermoplastic resin composition is kneaded using the above-mentioned extruder, and then extruded through a mold (die) to be molded.

[0024] The thermoplastic resin composition according to this embodiment contains a thermoplastic resin and a filler.

[0025] The thermoplastic resin includes polypropylene having an MFR of 20 g / 10 min or more and 60 g / 10 min or less at a temperature of 230°C and a load of 2.16 kgf. Here, MFR is melt mass-flow rate and can be measured, for example, in accordance with JIS K7210. The MFR of the polypropylene is preferably 25 g / 10 min or more. The MFR of the polypropylene is preferably 50 g / 10 min or less.

[0026] If the MFR of the polypropylene is less than 20 g / 10 min, it becomes difficult to extrude the molten resin from the mold, the extrusion speed decreases, and the productivity of the sheet-shaped extrusion molded product may decrease. If a polypropylene with an MFR of more than 60 g / 10 min is used, the fluidity may become too high, which may increase the thickness deviation of the sheet-shaped extrusion molded product, and it may also be difficult to obtain, so the upper limit of the MFR of the polypropylene is set to 60 g / 10 min.

[0027] The thermoplastic resin may contain a thermoplastic resin other than polypropylene as long as the fluidity of the thermoplastic resin composition is not impaired. Examples of the thermoplastic resin other than polypropylene include, but are not limited to, polyethylene, polybutylene, polystyrene, polyvinyl chloride, polycarbonate, polyethylene terephthalate, polyamide 66, and polyamide 6.

[0028] The filler contains wood flour and talc. By incorporating wood flour into the thermoplastic resin composition, the linear expansion coefficient of the sheet-like extrusion molded product can be reduced. Furthermore, the Mohs hardness of talc is 1, which is low among standard minerals. Therefore, by incorporating talc into the thermoplastic resin composition, the strength of the sheet-like extrusion molded product can be ensured while suppressing wear on the extruder (particularly the screw, gear, etc.).

[0029] The wood flour is not particularly limited, but examples thereof include sawdust from softwoods and / or hardwoods. The softwood is not particularly limited, but examples thereof include Western hemlock.

[0030] The wood flour preferably contains wood flour that passes through a 30 mesh (500 μm mesh size), more preferably a 36 mesh (425 μm mesh size), and even more preferably a 60 mesh (250 μm mesh size) sieve. By including wood flour with a small particle size in the thermoplastic resin composition, the linear expansion coefficient of the sheet-like extrusion molded product can be reduced.

[0031] The content of wood flour is 20 parts by mass or more, preferably 40 to 70 parts by mass, per 100 parts by mass of the total filler. If the content of wood flour is less than 20 parts by mass, the linear expansion coefficient of the sheet-like extrusion molded product may be high. In particular, if the content of wood flour is 40 parts by mass or more, the linear expansion coefficient of the sheet-like extrusion molded product can be reduced. On the other hand, if the content of wood flour exceeds 70 parts by mass, molding of the thermoplastic resin composition may become difficult.

[0032] The content of wood flour is preferably 35 parts by mass or more and 45 parts by mass or less per 100 parts by mass of the total of the thermoplastic resin and the filler, which makes it easier to mold the thermoplastic resin composition and also reduces the linear expansion coefficient of the sheet-shaped extrusion molded product.

[0033] The average particle size of the talc is preferably 12 μm or more, more preferably 14 μm or more. Here, the average particle size refers to the average particle size (D50) obtained by measuring the volumetric particle size distribution by laser diffraction. The average particle size of the talc is preferably 50 μm or less, more preferably 30 μm or less. This allows the linear expansion coefficient of the sheet-shaped extrusion molded product to be reduced.

[0034] The filler may further contain mica. The Mohs hardness of mica is 2.5 to 3. On the other hand, the Mohs hardness of talc is 1. Thus, the Mohs hardness of mica is greater than that of talc. Therefore, when the filler further contains mica, the strength of the sheet-shaped extrusion molded product can be increased.

[0035] When the filler further contains mica, the content of mica is preferably 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the total of the thermoplastic resin and the filler. By setting the content of mica to 10 parts by mass or less, wear on the extruder can be suppressed. Furthermore, by setting the content of mica to 1 part by mass or more, the strength of the sheet-like extrusion molded product can be increased.

[0036] The content of the filler is 60 parts by mass or more and 72 parts by mass or less, based on 100 parts by mass of the total of the thermoplastic resin and the filler. If the content of the filler is less than 60 parts by mass, the fluidity of the thermoplastic resin composition during extrusion molding may be too high, making molding difficult. On the other hand, if the content of the filler is more than 72 parts by mass, the fluidity of the thermoplastic resin composition during extrusion molding may be too low, making molding difficult.

[0037] The thermoplastic resin composition can be obtained by blending and kneading the thermoplastic resin and filler using a mixer such as a Henschel mixer. In this case, the MFR of the thermoplastic resin composition at a temperature of 230°C and a load of 2.16 kgf is preferably 2.0 g / 10 min or more and 6.0 g / 10 min or less.

[0038] Next, for example, the thermoplastic resin composition is kneaded using the above-mentioned extrusion molding machine, and then extruded through a mold (die) to obtain a sheet-like extrusion molded product. The thickness of the sheet-like extrusion molded product is not particularly limited, but is, for example, 0.5 mm or more and 3 mm or less. As mentioned above, a decorative sheet may be attached to the surface of the sheet-like extrusion molded product.

[0039] 3. Aspects As is apparent from the above embodiments, the present disclosure includes the following aspects.

[0040] A first aspect is a method for producing a sheet-like extrusion molded product, in which a thermoplastic resin composition is kneaded and then extruded through a mold. The thermoplastic resin composition contains a thermoplastic resin and a filler. The thermoplastic resin includes polypropylene having an MFR of 20 g / 10 min or more and 60 g / 10 min or less at a temperature of 230°C and a load of 2.16 kgf. The filler includes wood flour and talc. The content of the filler is 60 parts by mass or more and 72 parts by mass or less, relative to 100 parts by mass of the total of the thermoplastic resin and the filler. The content of the wood flour is 20 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass of the total of the filler.

[0041] According to this embodiment, it is possible to suppress wear on the extruder, improve the moldability of the thermoplastic resin composition, and produce a sheet-shaped extrusion molded product with a small linear expansion coefficient.

[0042] A second aspect is a method for producing a sheet-like extrusion-molded product based on the first aspect. In the second aspect, the filler further contains mica. The content of the mica is 10 parts by mass or less per 100 parts by mass of the thermoplastic resin and the filler combined.

[0043] According to this embodiment, the filler further contains mica, which can increase the strength of the sheet-like extrusion molded product. Furthermore, the mica content is 10 parts by mass or less, which can suppress wear on the extruder.

[0044] A third aspect is a method for producing a sheet-like extrusion molded product based on the first or second aspect. In the third aspect, the content of the wood flour is 40 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass of the total of the filler.

[0045] According to this embodiment, the wood flour content of 40 parts by mass or more can reduce the linear expansion coefficient of the sheet-shaped extrusion molded product, and the wood flour content of 70 parts by mass or less can suppress a decrease in the moldability of the thermoplastic resin composition.

[0046] A fourth aspect is a method for producing a sheet-like extrusion molded product according to any one of the first to third aspects, wherein the wood flour includes wood flour that passes through a 60 mesh sieve.

[0047] According to this embodiment, the coefficient of linear expansion of the sheet-shaped extrusion molded product can be reduced.

[0048] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited to the following examples.

[0049] 1. Samples (1) Materials The following materials were mixed in the amounts shown in Table 1 using a Henschel mixer to obtain thermoplastic resin compositions.

[0050] <Thermoplastic resin> Polypropylene 1: Trade name "BC03B" (MFR: 30 g / 10 min), manufactured by Japan Polypropylene Corporation Polypropylene 2: Trade name "BC3AD" (MFR: 10 g / 10 min), manufactured by Japan Polypropylene Corporation <Filler> <Wood flour> Wood flour 1: American hemlock sawdust (passed through a 40-mesh sieve) Wood flour 2: American hemlock sawdust (passed through a 60-mesh sieve) <Talc> Talc 1: Trade name "sss" (average particle size 12 μm), manufactured by Nippon Talc Co., Ltd. Talc 2: Trade name "MS-T" (average particle size 20 μm), manufactured by Nippon Talc Co., Ltd. <Mica> Mica: Trade name "60-C" manufactured by Kuraray Co., Ltd. (2) Production method Using the above-mentioned extrusion molding machine, the thermoplastic resin composition was kneaded and then extruded through a mold (die) to obtain a sheet-like extrusion molded product. Specifically, the thermoplastic resin composition was fed into an extruder (twin-screw co-rotating extruder) and kneaded, then extruded through a T-die via a gear pump, and then wound around a cooling roll (three-roll system) for continuous molding. In this way, a sheet-like extrusion molded product with a thickness of 1.3 mm and a width of 20 cm was obtained. The extrusion speed was approximately 5 to 15 m / min.

[0051] 2. Tests (1) Moldability The appearance of the resin extruded from the T-die was observed, and the observation results were classified according to the following evaluation criteria to evaluate the moldability.

[0052] <Evaluation criteria> A: Discharge from the T-die is stable and molding is easy. B: Discharge from the T-die is unstable and molding is difficult (the optimum ranges for discharge pressure and discharge temperature are narrow and the control conditions are strict). C: Molding is not possible (there are no optimum values ​​for discharge pressure or discharge temperature and therefore discharge is not possible, or the optimum range is extremely narrow and therefore not suitable for continuous production).

[0053] (2) Linear expansion coefficient The linear expansion coefficient of the sheet-shaped extrusion molded product was measured using the method of thermomechanical analysis (TMA) specified in JIS K 7197. Note that the following evaluation was not performed for Comparative Examples 6, 7, 16, and 17, whose moldability was evaluated as "C."

[0054] (3) MFR The MFR of a thermoplastic resin composition was measured at a temperature of 230° C. and a load of 2.16 kgf in accordance with JIS K7210.

[0055] (4) Abrasion The inside of the extruder was observed before and after a predetermined period of production of a sheet-like extrusion molded product, and the results of the observations were classified into the following evaluation criteria to evaluate abrasion.

[0056] <Evaluation criteria> A: Almost no wear is observed on the screw, gears, etc. of the extruder. B: Slight wear is observed on the screw, gears, etc. of the extruder. C: Clear wear is observed on the screw, gears, etc. of the extruder.

[0057]

[0058] From Table 1, it was confirmed that Examples 1 to 9 suppressed wear on the extruder, improved the moldability of the thermoplastic resin composition, and were able to produce sheet-like extrusion molded products with a small linear expansion coefficient, compared to Comparative Examples 1 to 17.

[0059] From Examples 1 and 2, it was confirmed that the linear expansion coefficient of the sheet-like extrusion molded product can be made smaller by including wood flour that passes through a 60-mesh sieve.

[0060] From Comparative Examples 16 and 17, it was confirmed that when the MFR of polypropylene at a temperature of 230° C. and a load of 2.16 kgf is less than 20 g / 10 min, moldability decreases.

[0061] From Comparative Examples 1 to 7 and 14, it was confirmed that moldability deteriorates when the filler content deviates from the range of 60 parts by mass or more and 72 parts by mass or less relative to 100 parts by mass of the total of the thermoplastic resin and filler.

[0062] It was confirmed from Comparative Examples 5 and 8 to 10 that the linear expansion coefficient increases when the wood flour content is less than 20 parts by mass relative to 100 parts by mass of the total filler. Comparative Example 15 also has a wood flour content of less than 20 parts by mass relative to 100 parts by mass of the total filler, but the linear expansion coefficient is small. Comparing Comparative Examples 9 and 15, it is presumed that this is due to mica.

[0063] From Comparative Examples 3 and 11 to 14, it was confirmed that when the content of wood flour exceeds 70 parts by mass with respect to 100 parts by mass of the total filler, moldability decreases.

[0064] From Comparative Example 15, it was confirmed that when the content of mica exceeds 10 parts by mass relative to 100 parts by mass of the total of the thermoplastic resin and the filler, wear of the extruder occurs.

Claims

1. A method for producing a sheet-like extrusion molded product by kneading a thermoplastic resin composition and then extruding it through a die, wherein the thermoplastic resin composition contains a thermoplastic resin and a filler, the thermoplastic resin contains polypropylene having an MFR of 20 g / 10 min or more and 60 g / 10 min or less at a temperature of 230°C and a load of 2.16 kgf, and the filler contains wood flour and talc, the content of the filler is 60 parts by mass or more and 72 parts by mass or less per 100 parts by mass of the total of the thermoplastic resin and the filler, and the content of the wood flour is 20 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the total of the filler.

2. The method for producing a sheet-like extrusion molded product according to claim 1, wherein the filler further contains mica, and the content of the mica is 10 parts by mass or less per 100 parts by mass of the thermoplastic resin and the filler combined.

3. The method for producing a sheet-like extrusion molded product according to claim 1, wherein the content of the wood flour is 40 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the total of the filler.

4. The method for producing a sheet-like extrusion molding according to any one of claims 1 to 3, wherein the wood flour includes wood flour that passes through a 60 mesh sieve.

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