Method for producing recycled polypropylene resin composition

Abstract

To provide a recycled polypropylene resin composition having excellent long-term thermostability, a method for producing the same and a molding.SOLUTION: A recycled polypropylene resin composition comprises used waste polypropylene resin, the composition comprising talc, with the content of talc being 0.1 mass% or more and 4.6 mass% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a recycled polypropylene resin composition, a method for producing the same, and a molded article thereof. [Background technology]

[0002] Today, home appliances such as air conditioners, televisions, refrigerators, and washing machines, as well as office equipment such as copiers and personal computers, are widely used. The increasing volume of waste thermoplastic resins used in the housings and mechanical components of these products and devices has led to a growing demand for the reuse of such waste. In April 2001, the Home Appliance Recycling Law (the Law for Recycling of Specified Household Appliances) was enacted with the aim of promoting resource utilization and reducing waste. The Home Appliance Recycling Law mandates the recycling of home appliances discarded from ordinary households and offices (air conditioners, CRT televisions, LCD / plasma televisions, refrigerators / freezers, washing machines / clothes dryers) and sets legal standards for the recycling rate of each product (80% or more for air conditioners, 55% or more for CRT televisions, 74% or more for LCD / plasma televisions, 70% or more for refrigerators / freezers, and 82% or more for washing machines / clothes dryers).

[0003] Following the enforcement of the Home Appliance Recycling Law, research and development into recycling technologies for waste thermoplastic resins used in discarded products (hereinafter referred to as "used waste thermoplastic resins") is progressing in various fields. Among the various recycling methods proposed, material recycling, which reuses used waste thermoplastic resins as thermoplastic resin components in products, is attracting attention from the perspective of resource circulation and reducing environmental impact.

[0004] However, used thermoplastic resin waste is often deteriorated by heat, ultraviolet rays, etc. in the usage environment, and even if used thermoplastic resin waste is crushed and remolded as is, it is difficult to obtain properties equivalent to those of a molded product of a virgin (non-recycled) thermoplastic resin composition. For this reason, attempts have been made to produce molded products having properties equivalent to those of a molded product of a virgin thermoplastic resin composition by adding virgin thermoplastic resin, fillers, and various additives to used thermoplastic resin waste, while recycling resources.

[0005] Molded articles of polypropylene resin compositions are widely used in durable consumer goods such as home appliances, office automation equipment, and information devices due to their excellent strength, rigidity, chemical resistance, and moldability, and these resin compositions often contain talc as an inorganic filler. Patent Document 1 discloses a method for producing a recycled polypropylene resin composition using, as a raw material, waste polypropylene resin used in these discarded products (hereinafter referred to as "waste polypropylene resin"), a pulverized waste polypropylene resin, which is known to contain 90% by mass or more of the inorganic filler as talc, as a raw material, with the aim of producing a molded article that exhibits a higher flexural modulus and a higher deflection temperature under load compared to a molded article obtained by directly remolding waste polypropylene resin. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5692666 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when a molded article of a recycled polypropylene resin composition is produced using waste polypropylene resin as a raw material, there is a problem that the long-term thermal stability is insufficient compared to a molded article produced using virgin polypropylene resin as a raw material.

[0008] The present invention has been made based on the above circumstances, and its object is to provide a recycled polypropylene resin composition having excellent long-term thermal stability, a method for producing the same, and a molded article thereof. [Means for solving the problem]

[0009] As a result of intensive research to solve the above-mentioned problems, the present inventors discovered that when recycled polypropylene resin waste is recycled to produce a recycled polypropylene resin composition, the long-term thermal stability becomes insufficient due to the talc content in the recycled polypropylene resin composition, and thus completed the present invention.

[0010] That is, the invention made to solve the above problem is a recycled polypropylene resin composition containing used polypropylene resin waste, characterized in that it contains talc and the talc content is 0.1 mass% or more and 4.6 mass% or less.

[0011] Another invention made to solve the above problems is a molded article characterized by being molded from the above recycled polypropylene resin composition.

[0012] Another invention made to solve the above-mentioned problems is a method for producing a recycled polypropylene resin composition using used polypropylene resin waste as a raw material, comprising: a first step of recovering used polypropylene resin waste from at least one product or device selected from the group consisting of home appliances, office automation equipment, information equipment, and communication equipment; a second step of measuring the talc content in the used polypropylene resin waste recovered in the first step; a third step of adding and mixing at least one of polypropylene resin and talc to the used polypropylene resin waste recovered in the first step according to the measurement results of the talc content obtained in the second step, thereby obtaining a mixture adjusted to have a talc content of 0.1% by mass or more and 4.6% by mass or less; and a fourth step of extrusion-molding the mixture obtained in the third step to obtain a recycled polypropylene resin composition. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a recycled polypropylene resin composition having excellent long-term thermal stability, a method for producing the same, and a molded article thereof. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a process diagram showing a method for producing a recycled polypropylene resin composition according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention includes a recycled polypropylene resin composition, a method for producing the same, and a molded article thereof, which will be described in detail below.

[0016] <Recycled polypropylene resin composition> The recycled polypropylene resin composition of the present invention is obtained by recycling used polypropylene resin waste. The recycled polypropylene resin composition of the present invention may contain optional components within a range that does not impair the effects of the present invention.

[0017] The content of the polypropylene resin in the recycled polypropylene resin composition of the present invention is determined so that the total content of the polypropylene resin, including the contents of talc and optional components, is 100% by mass.

[0018] Examples of optional components include antioxidants (phenolic, phosphorus-based, sulfur-based, etc.), ultraviolet absorbers (benzophenone-based, hindered amine-based, etc.), fillers (glass fiber, mica, calcium carbonate, barium sulfate, etc.), flame retardants, flame retardant assistants, anti-drip agents (fluorine-based resins, etc.), lubricants, plasticizers, stabilizers, release agents, antistatic agents, colorants (pigments, dyes, etc.), metal deactivators, neutralizing agents, and dispersants.

[0019] (Used polypropylene resin waste material) Examples of used polypropylene resin waste materials that can be used include housings and mechanical parts recovered from at least one product or device selected from the group consisting of used home appliances such as washing machines, refrigerators, and air conditioners, office automation equipment, information equipment, and communication equipment. Known methods for recovering the waste polypropylene resin materials, such as manual disassembly and mechanical sorting, can be used.

[0020] The composition of the used polypropylene resin waste is not particularly limited, but it is preferable that the waste contains, as a main component, a polypropylene resin used as a plastic material for housings and mechanical parts recovered from used washing machines, refrigerators, and air conditioners, and is suitable for recycling. The used polypropylene resin waste may or may not contain talc.

[0021] (talc) Talc is a magnesium silicate hydrate (Mg3Si4O 10 (OH)2), also known as talc.

[0022] The talc content in the recycled polypropylene resin composition of the present invention is 0.1% by mass or more and 4.6% by mass or less. A more preferred range is 0.8% by mass or more and 4.6% by mass or less. By setting the talc content at or below the above upper limit, excellent long-term thermal stability can be achieved in a recycled polypropylene resin composition recycled from used polypropylene resin waste. By setting the talc content at or above the above lower limit, talc acts as a crystal nucleating agent, improving rigidity and heat resistance. As mentioned above, used polypropylene resin waste deteriorates due to heat, ultraviolet rays, etc. in the usage environment, reducing long-term thermal stability. Therefore, it is presumed that the above upper limit of the talc content is lower than when new material (not recycled) is used.

[0023] The talc in the recycled polypropylene resin composition of the present invention may be derived from talc contained in used polypropylene resin waste, talc contained in new material, or unused (brand new) talc, but from the viewpoint of resource recycling, it is preferable that it is derived from talc contained in used polypropylene resin waste.

[0024] <Method of producing recycled polypropylene resin composition> As shown in Figure 1, the method for producing a recycled polypropylene resin composition of the present invention includes the following steps: a first step of recovering used polypropylene resin waste from at least one product or device selected from the group consisting of home appliances, office automation equipment, information equipment, and communication equipment; a second step of measuring the talc content in the used polypropylene resin waste recovered in the first step; a third step of adding and mixing at least one of polypropylene resin and talc to the used polypropylene resin waste recovered in the first step based on the talc content measurement results obtained in the second step, thereby obtaining a mixture adjusted to have a talc content of 0.1% by mass or more and 4.6% by mass or less; and a fourth step of extrusion-molding the mixture obtained in the third step to obtain a recycled polypropylene resin composition.

[0025] In the first step, for example, waste products such as used home appliances such as refrigerators, washing machines, and air conditioners are collected from households. Next, the collected waste products are dismantled to obtain used polypropylene resin waste material, which is then crushed to obtain crushed material. The used polypropylene resin waste material collected in the first step may be used polypropylene resin waste material containing talc or used polypropylene resin waste material not containing talc.

[0026] The method for measuring the talc content in the second step is not particularly limited, and known measurement methods such as an ashing method, an X-ray fluorescence method, an atomic absorption spectroscopy method, an ICP method (inductively coupled plasma), etc. For example, in the ashing method, as in the examples described below, about 5 g of the crushed material is placed in a crucible and burned (ashed), and then the residue (ash content) is weighed, whereby the talc content in the crushed material can be measured.

[0027] In the above-mentioned third step, the polypropylene resin and talc added to the used polypropylene resin waste material collected in the first step may be unused or may be obtained by dismantling the collected waste products. In other words, the polypropylene resin and talc added in the third step may be any of unused polypropylene resin (new material) containing talc, unused polypropylene resin (new material) not containing talc, used polypropylene resin waste material containing talc, used polypropylene resin waste material not containing talc, and unused talc (new material), and two or more of these may be used in combination.

[0028] The virgin talc is not particularly limited, and examples thereof include commercially available products described in paragraph

[0019] of JP 2018-150483 A, specifically, products manufactured by Nippon Talc Co., Ltd. under the product names: Nanotalc Nano Ace series D-1000 and FG-15, Ultrafine Talc SG series SG-2000, SG-200, SG-200N15, Fine Talc Micro Ace series SG-95, P-8, P-6, P-4, P-3, P-2, L-1, K-1, LG, RA-3, PAOG-3, general-purpose talc MS-P, MS-K, SWE, Shimgon, SSS, RA, PA-OG, and products manufactured by Fuji Talc Kogyo Co., Ltd. under the product name: Ultrafine Powder Gray Examples of talc include FH104, FH105, FH106, FH108, FL108, FG105, FG106, FH205, FH206, and FS404, fine powder grades ML110, ML112, ML115, MG113, MG115, MS410, and MS412, general-purpose grades RL119, RL217, RG319, RH415, RS415, RS515, and RS613, and Fukuoka Talc Kogyosho Co., Ltd. product names include general-purpose talc FT-96, FT-92, FT-88, FT-84, FT-80, and FT-76, fine particle talc MF-96, MF-92, MF-88, and MF-84, and ultrafine particle talc PS-5000H and PS-85H.

[0029] In the third step, what is added to the used polypropylene resin waste to adjust the talc content to 0.1% by mass or more and 4.6% by mass or less may be virgin polypropylene resin or virgin talc, but from the viewpoint of resource reuse, it is preferable to obtain a mixture adjusted to have a talc content of 0.1% by mass or more and 4.6% by mass or less by mixing multiple used polypropylene resin waste materials recovered in the first step with different talc contents. For example, if the talc content of the used polypropylene resin waste material recovered in the first step exceeds 4.6% by mass, a used polypropylene resin waste material recovered in the first step with a talc content less than 4.6% by mass can be added and mixed to obtain a mixture adjusted to have a talc content of 0.1% by mass or more and 4.6% by mass or less.

[0030] In the above-mentioned third step, it is more preferable to adjust the talc content in the above-mentioned mixture to be 0.8% by mass or more and 4.6% by mass or less.

[0031] In addition, in the raw materials mixed in the above-mentioned third step, the above-mentioned optional components may be added within a range that does not impair the effects of the present invention.

[0032] In the above-mentioned fourth step, for example, by extrusion-molding the mixture obtained in the above-mentioned third step, a recycled polypropylene resin composition in the form of pellet-like raw materials is obtained.

[0033] <Formed body> The formed body of the present invention is a formed body formed from the recycled polypropylene resin composition of the present invention. The recycled polypropylene resin composition of the present invention can be formed into formed bodies such as housings and mechanical components of home appliances such as air conditioners, TVs, refrigerators, washing machines, etc. and OA equipment by melt molding or the like. The formed body of the present invention may be formed only from the recycled polypropylene resin composition of the present invention, or may have portions formed from other materials. As shown in the examples described later, the formed body of the present invention has excellent long-term thermal stability by being formed from the recycled polypropylene resin composition of the present invention.

Examples

[0034] Hereinafter, the present invention will be described based on examples and comparative examples, but the present invention is not limited to these examples.

[0035] First, the components used as raw materials in the examples and comparative examples are as follows.

[0036] <Component A>: Used polypropylene resin waste material (talc content: 3.4% by mass) Component A is a polypropylene resin composition recovered from used home appliances (washing machines, refrigerators, air conditioners) and having a talc content of 3.4% by mass measured in the second step. <Component B>: Used polypropylene resin waste material (talc content: 15% by mass) Component B is a polypropylene resin composition recovered from used household appliances (air conditioners) and having a talc content of 15% by mass measured in the second step. <Component C>: Used polypropylene resin waste material (talc content: 0.1% by mass) Component C is a polypropylene resin composition recovered from used household appliances (refrigerators) and having a talc content of 0.1% by mass measured in the second step. <Component D>: Talc · Talc D: Talc derived from Component A contained in the resin composition obtained by mixing Components A to C · Talc D′: Talc derived from Component B contained in the resin composition obtained by mixing Components A to C · Talc D″: Talc derived from Component C contained in the resin composition obtained by mixing Components A to C <Component E>: Phenolic antioxidant · Adeka Stab AO-60 (trade name, manufactured by ADEKA CORPORATION) <Component F>: Phosphite antioxidant · Adeka Stab 2112 (trade name, manufactured by ADEKA CORPORATION)

[0037] <Production of recycled polypropylene resin composition and molded body> [Examples 1 to 6, and Comparative Examples 1 and 2] According to the process diagram of FIG. 1, used polypropylene resin waste materials were recycled. First, used refrigerators, washing machines, and air conditioners were collected, and then, by manual disassembly, polypropylene resin parts were collected from the collected used refrigerators, washing machines, and air conditioners (first step). The collected parts were crushed using a crusher to obtain a crushed product having a particle size of about 12 mm.

[0038] About 5 g of the crushed product was placed in a crucible and burned (ashed), and then the residue (ash) was weighed to measure the talc content contained in the above-mentioned crushed product (second step).

[0039] Next, the ingredients A to F were blended in the mass proportions shown in Table 1 below, and the resulting mixture was mixed using a tumbler mixer to obtain a mixture (third step).

[0040] Next, this mixture was heated, melted, and kneaded at a set temperature of 200°C using a twin-screw melt-kneading extruder (manufactured by Technovel Co., Ltd.) with a screw diameter of 27 mm and an effective screw length L / D of 45. The melt-kneaded mixture was extruded into strands and cut using a pelletizer to obtain a pelletized recycled polypropylene resin composition (Step 4). The extrusion conditions were a discharge rate of 12 kg / h, a screw rotation speed of 150 rpm, and a feeder rotation speed of 23 rpm.

[0041] The pelletized recycled polypropylene resin composition was used in a 10-ton vertical injection molding machine (manufactured by Nissei Plastic Industrial Co., Ltd.) to produce test pieces for measuring physical properties in accordance with ASTM standards under injection molding conditions of a set temperature of 220°C, a mold temperature of 40°C, and a cooling time of 30 seconds.

[0042] <Evaluation> The recycled polypropylene resin compositions of the examples and comparative examples were measured according to the following methods to evaluate their long-term thermal stability and rigidity. The blending ratios of raw materials for each example and comparative example, as well as the evaluation results, are shown in Table 1.

[0043] (Method for evaluating long-term thermal stability) The oven test was carried out using a test machine DKM600 (product name, manufactured by Yamato Scientific Co., Ltd.).

[0044] The ASTM-compliant physical property measurement test specimens prepared as described above were placed in a constant temperature incubator set at 140°C and removed after 1000 hours at 140°C. A bending test was performed using these test specimens to measure their bending strength in accordance with JIS K 7171. A bending strength of 90% or more of the initial bending strength was evaluated as good (◯), and a bending strength of less than 90% was evaluated as poor (×).

[0045] (Method for evaluating rigidity) The rigidity of the ASTM-compliant test pieces for measuring physical properties prepared as described above was evaluated by measuring the flexural modulus in accordance with JIS K 7171. A flexural modulus of 600 MPa or more was judged as good (◯), and a flexural modulus of less than 600 MPa was judged as poor (×).

[0046] [Table 1]

[0047] As is clear from Table 1, the recycled polypropylene resin compositions of Examples 1 to 6, which are recycled polypropylene resin compositions containing used polypropylene resin waste and contain talc, and in which the talc content is 0.1% by mass or more and 4.6% by mass or less, were evaluated to have excellent long-term thermal stability and rigidity.

[0048] In contrast, Comparative Examples 1 and 2, which did not satisfy these requirements (the talc content exceeded 4.6% by mass), were evaluated as inferior to the Examples in terms of long-term thermal stability.

[0049] <Other embodiments> It should be noted that the embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention should not be interpreted solely by the above-described embodiments, but should be defined by the claims. The technical scope of the present invention also includes all modifications within the scope and meaning equivalent to the claims.

Claims

1. A method for producing a recycled polypropylene resin composition using used polypropylene resin waste as a raw material, A first step of recovering used polypropylene resin waste from at least one product or device selected from the group consisting of home appliances, office automation equipment, information equipment, and communication equipment; A second step of measuring the content of talc in the used polypropylene resin waste material recovered in the first step; A third step of adding and mixing at least one of polypropylene resin and talc to the used polypropylene resin waste material recovered in the first step according to the measurement result of the talc content obtained in the second step, thereby obtaining a mixture adjusted to have a talc content of 0.1% by mass or more and 4.6% by mass or less; A fourth step of extruding the mixture obtained in the third step to obtain a recycled polypropylene resin composition; A method for producing a recycled polypropylene resin composition, comprising:

2. A method for producing the recycled polypropylene resin composition according to claim 1, In the third step, a plurality of used polypropylene resin waste materials having different talc contents recovered in the first step are mixed to obtain a mixture having a talc content adjusted to 0.1% by mass or more and 4.6% by mass or less. This is a method for producing a recycled polypropylene resin composition.

3. A mixture preparation process in which a mixture containing talc-containing waste polypropylene resin is mixed with at least one of polypropylene resin and talc to obtain a mixture adjusted to have a talc content of 0.1% by mass or more and 4.6% by mass or less; A resin composition preparation step in which the mixture obtained in the mixture preparation step is extruded to obtain a recycled polypropylene resin composition; A method for producing a recycled polypropylene resin composition, comprising:

4. A method for producing a recycled polypropylene resin composition as described in claim 3, characterized in that a measurement process is carried out to measure the talc content in the used polypropylene resin waste material before carrying out the mixture preparation process.

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