Resin compositions, resin molded articles and structures

Abstract

The resin composition containing recycled block polypropylene ensures strength and rigidity equivalent to virgin material, maintains the fluidity required for injection molding, and facilitates repeated recycling. [Solution] A resin composition comprising recycled polypropylene and fibers, wherein the recycled polypropylene includes block polypropylene, the average fiber length of the fibers is 1400 μm or more, and the percentage of fibers with a fiber length of 1200 μm or more is 50% or more.

Description

Technical Field

[0001] The present disclosure relates to a resin composition, a resin molded article, and a structure.

Background Art

[0002] In recent years, in the social trend of converting from the conventional linear economy of mass consumption and mass disposal to a circular economy, the social demand for utilizing recycled materials obtained by recovering and recycling materials from waste has been increasing. Along with this, recycled materials have a problem that their physical properties deteriorate due to the heat history and the inclusion of foreign substances in the recycling process compared to virgin materials.

[0003] To improve the physical properties of recycled materials, adding glass fiber reinforced plastic (GFRP) or mixing with different polymers can be considered as countermeasures.

[0004] In Patent Document 1, regarding suppressing the deterioration of the mechanical properties of a resin composition recovered from waste, attention is paid to the problem that chlorine elements, which are considered to be derived from chlorine-based resins mixed in the recovered resin, inhibit the bonding between the glass fiber interface and the resin matrix, significantly reducing mechanical properties such as tensile strength, flexural strength, and impact strength. In a glass fiber reinforced modified polyphenylene ether resin composition containing a recovered thermoplastic resin containing chlorine elements and a polyphenylene ether resin, a technique of adding a specific amount of compounds such as magnesium oxide and magnesium hydroxide is disclosed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The glass fiber-reinforced modified polyphenylene ether resin composition described in Patent Document 1 is prepared by mixing a thermoplastic resin with a polyphenylene ether resin, which is a different polymer. Therefore, in subsequent recycling, it is considered that either the thermoplastic resin or the polyphenylene ether resin, which are constituent elements, may become impurities, potentially making repeated recycling difficult.

[0007] This disclosure aims to ensure that a resin composition containing recycled block polypropylene has strength and rigidity equivalent to that of virgin material, while also ensuring the fluidity required for injection molding, and facilitating repeated recycling. [Means for solving the problem]

[0008] The resin composition relating to this disclosure comprises recycled polypropylene and fibers, wherein the recycled polypropylene includes block polypropylene, the average fiber length of the fibers is 1400 μm or more, and the percentage of fibers with a fiber length of 1200 μm or more is 50% or more. [Effects of the Invention]

[0009] According to this disclosure, a resin composition containing recycled block polypropylene can be made to have strength and rigidity equivalent to that of virgin material, while also ensuring the fluidity required for injection molding, and facilitating repeated recycling. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing a washing machine and dryer equipped with a resin molded product according to an embodiment. [Figure 2] This is a perspective view showing a vacuum cleaner equipped with a resin molded product of an embodiment. [Figure 3] This table shows the measurement results of the physical properties of the resin composition of this disclosure. [Figure 4] Figure 3 is a graph showing the relative frequency distribution of fiber lengths of the fibers contained in the resin composition of item (5). [Figure 5]Figure 3 shows graphs illustrating the relative frequency distribution and cumulative relative frequency distribution of fiber lengths of the fibers contained in the resin composition of item (5). [Figure 6] Figure 3 shows a table illustrating the statistical values ​​of the fiber lengths of the fibers contained in the resin composition of item (5). [Modes for carrying out the invention]

[0011] Embodiments relating to this disclosure will be described below with reference to the drawings. Within the description of one embodiment below, other embodiments applicable to that embodiment will also be described as appropriate. This disclosure is not limited to the following embodiment, and different embodiments can be combined or modified as appropriate without significantly impairing the effects of this disclosure. In addition, the same reference numerals will be used for the same components, and redundant descriptions will be omitted. Furthermore, components having the same function will be given the same name. The illustrations are for illustrative purposes only, and for illustrative purposes, the actual configuration may be changed or some components may be omitted or modified between drawings without significantly impairing the effects of this disclosure. Also, it is not necessary for the same embodiment to have all the components.

[0012] The resin composition of this disclosure comprises recycled block polypropylene and glass fibers having an average fiber length of 1400 μm or more and a fiber length of 1200 μm or more, with a fiber ratio of 50% or more. Hereinafter, polypropylene will be abbreviated as "PP" and recycled block polypropylene as "recycled block PP". The resin composition of this disclosure may consist only of recycled block PP and glass fibers, or it may contain other components (colorants, antioxidants, etc.). The glass fibers are components that reinforce the recycled block PP and are usually dispersed throughout the recycled block PP.

[0013] The recycled block PP is, for example, PP obtained by recycling market-collected waste block PP. It may also be unused material. Such PP is, for example, obtained by subjecting market-collected waste PP to processes such as crushing, washing, and melting, and made into, for example, pellets. The recycled block PP may contain fibers (for example, glass fibers, carbon fibers, etc.).

[0014] In summary, as the recycled PP, recovered block PP recovered from unused materials or used waste materials is preferably used.

[0015] The recycled block PP is, for example, PP derived from household electrical appliances. PP is often used in household electrical appliances. Also, recycled PP derived from household electrical appliances has the advantage that it is easy to use as a material for a resin composition having desired physical properties because the range of physical properties (tensile strength, flexural modulus, etc.) is limited. Also, by limiting the type of resin to those having PP as the main component, optical sorting can be facilitated.

[0016] The fibers are so-called reinforcing fibers. By mixing the fibers, the physical properties of the resin composition can be improved. In other words, the matrix resin can be strengthened. The fibers are, for example, configured to include at least one of virgin fibers (fibers made of virgin materials) and recycled fibers. In particular, from the viewpoint of improving the physical properties of the resin composition, it is preferable to use virgin fibers. On the other hand, from the viewpoints of reducing the manufacturing cost of the resin composition and increasing the usage rate of recycled materials in the resin composition, it is preferable to use recycled fibers.

[0017] The fibers include at least one of glass fibers and carbon fibers. These fibers are effective in improving the strength of the recycled block PP. Among them, from the viewpoint of reducing the manufacturing cost, it is preferable to use glass fibers.

[0018] The fibers can be mixed with the recycled block PP, for example, in the form of a masterbatch.

[0019] The fiber has an average fiber length of 1400 μm or more, and the number fraction of fibers with a fiber length of 1200 μm or more is 50% or more. By having such a configuration for the fiber, the flexural modulus (rigidity), flexural strength, tensile yield point strength, etc. of the recycled block PP can be improved.

[0020] In the resin composition of the present disclosure, it is desirable that the fiber content is 15% by mass or more and 40% by mass or less. By including the fiber at this ratio, the recycled block PP can be strengthened. If the fiber content is less than 15% by mass, the strength of the resin composition becomes low, which is not desirable. On the other hand, if the fiber content is greater than 40% by mass, in addition to the fluidity of the resin composition becoming low, the weight of the resin molded product increases, which is not desirable.

[0021] FIG. 1 is a perspective view showing a washing and drying machine including a resin molded product of an embodiment.

[0022] The washing and drying machine 10 shown in this figure includes an outer tub 11, a rotary drum 12, and a front door 13. An outer tub cover is attached to the outer tub 11. The outer tub 11, the outer tub cover, etc. are resin molded products and are molded products of the resin composition of the present disclosure.

[0023] The above resin molded product is produced by injection molding. That is, the above resin molded product is an injection molded product. For this reason, the above resin molded product can be made into a desired shape relatively easily.

[0024] Since the washing and drying machine 10 has a rotary drum 12, a predetermined strength is required for the resin molded products such as the outer tub 11 and the outer tub cover.

[0025] FIG. 2 is a perspective view showing a vacuum cleaner including a resin molded product of an embodiment.

[0026] The vacuum cleaner 20 shown in this figure comprises a head 21, an extension pipe 22, and a main body 23. The head 21, extension pipe 22, etc., are molded resin products, and are molded products of the resin composition of this disclosure. The vacuum cleaner 20 is configured to be charged by being placed on a charging base 24. The main body 23 and charging base 24 may also be formed from the resin composition of this disclosure. This is because the head 21, extension pipe 22, main body 23, and charging base 24 are all subject to strong forces such as collisions, and therefore require high strength. In particular, the extension pipe 22 requires flexibility rigidity, and the resin composition of this disclosure is suitable for this purpose.

[0027] By applying the resin composition of this disclosure to various parts in this manner, it is possible to increase the proportion of recycled block PP. Furthermore, the extension pipe 22 is a part that requires a certain degree of fluidity because the resin flow length in injection molding is long. As described later, the resin composition of this disclosure has a high melt flow rate (MFR), so even when applied to the extension pipe 22, it can suppress molding defects and maintain strength.

[0028] According to this disclosure, by mixing highly fluid recycled block polypropylene with glass fibers capable of improving strength and rigidity, it is possible to ensure strength, rigidity, and fluidity while also improving the utilization rate of recycled materials.

[0029] Although not shown in the illustrations, the resin composition of this disclosure and the resin molded articles made using it may be used not only in washing machines and dryers and vacuum cleaners, but also in components of household electrical appliances such as refrigerators, cooking appliances, rice cookers, air conditioners, and air purifiers.

[0030] The present disclosure will be explained in more detail below with reference to examples. [Examples]

[0031] The physical properties of resin compositions were measured by varying the glass fiber content and fiber length. The glass fiber content was calculated by heating a sample of the resin composition to approximately 500-600°C to volatilize the resin components and measuring the mass of the residue. The fiber length was obtained by extracting the shape and dimensions of the fibers from images taken using an optical microscope and measuring the length of each fiber.

[0032] The measured physical properties were tensile yield strength, tensile elongation at fracture, flexural strength, flexural modulus, Izod impact strength, heat distortion temperature, and MFR. Of these, tensile yield strength and tensile elongation at fracture were measured according to ASTM D638, flexural strength and flexural modulus according to ASTM D790, Izod impact strength according to ASTM D256, heat distortion temperature according to ASTM D648, and MFR according to ASTM D1238. The Izod impact strength was measured under temperature conditions of 23°C and -10°C. The heat distortion temperature was measured under a load of 4.6 N. The MFR was measured under conditions of a temperature of 230°C and a load of 2.15 kg.

[0033] Figure 3 is a table showing these measurement results.

[0034] In this table, item (1) of the resin composition is virgin homo-PP, not recycled PP. Furthermore, this resin composition contains 20% by mass of glass fibers with an average fiber length of less than 1400 μm. Here, virgin homo-PP refers to virgin polypropylene, which is a homopolymer of propylene.

[0035] The resin composition in item (2) is a mixture of virgin homo-PP and recycled block PP. It contains 50% by mass of virgin homo-PP and 30% by mass of recycled block PP. This resin composition also contains 20% by mass of glass fibers with an average fiber length of less than 1400 μm. Here, recycled block PP is recycled block PP, which is a copolymer of propylene and ethylene. In other words, it is a recycled block PP material. Block PP has higher fluidity than homo-PP.

[0036] The resin compositions for items (3) to (5) are recycled block PP.

[0037] Of these, item (3) of the resin composition contains 20% by mass of glass fibers with an average fiber length of less than 1400 μm.

[0038] The resin composition of item (4) contains 15% by mass of glass fibers with an average fiber length of 1400 μm or more.

[0039] The resin composition of item (5) contains 20% by mass of glass fibers with an average fiber length of 1400 μm or more.

[0040] The resin compositions in items (4) and (5) are the resin compositions of the examples. On the other hand, item (3) is the resin composition of the comparative example.

[0041] Comparing item (1) and item (5), the resin composition of item (5), which is prepared by including 20% ​​by mass of glass fibers with an average fiber length of 1400 μm or more in the matrix (base material) of recycled block PP, has a flexural modulus that is equal to or better than that of the resin composition of item (1), which is prepared by including 20% ​​by mass of fibers with an average fiber length of less than 1400 μm in virgin homo PP, and a MFR that is approximately 90% higher. Therefore, the resin composition of item (5) can be suitably used in resin molded products that require fluidity. This makes it possible to improve the utilization rate of recycled materials.

[0042] Furthermore, comparing item (2) and item (5), the resin composition of item (5), which does not contain virgin homo PP, has a flexural modulus that is equal to or better than the resin composition of item (2), which is a mixture of virgin homo PP and recycled block PP, and the MFR is approximately 30% higher. Therefore, by using the resin composition of item (5), the desired physical properties can be obtained without mixing in homo PP. Block PP is also preferable from a procurement standpoint because it is more readily available than homo PP.

[0043] Comparing item (3) and item (4), the resin composition of item (3) has a lower Izod impact strength. In this respect, the resin composition of item (3) is inferior to the resin composition of item (4), and is therefore used as a comparative example.

[0044] Comparing item (4) and item (5), the resin composition of item (4), which has a glass fiber content of 15% by mass, has lower flexural modulus and flexural strength compared to the resin composition of item (5), which has a glass fiber content of 20% by mass, but its MFR is approximately 20% higher. Therefore, the resin composition of item (4) can be suitably used in resin molded products that require a high MFR.

[0045] The measurement results for the resin compositions of items (4) and (5), which are examples, can be summarized as follows.

[0046] The preferred ranges for the properties of the resin composition in the examples are a flexural strength of 65 to 80 MPa, a flexural modulus of 3000 to 3800 MPa, an Izod impact strength (23°C) of 90 to 110 J / m, an Izod impact strength (-10°C) of 65 to 80 J / m, and an MFR of 15 to 25 g / 10 min. Needless to say, higher flexural strength, flexural modulus, and Izod impact strength are desirable.

[0047] Figure 4 is a graph showing the relative frequency distribution of fiber lengths of the fibers contained in the resin composition of item (5) shown in Figure 3. The horizontal axis represents fiber length (logarithmic scale), and the vertical axis represents relative frequency.

[0048] Figure 5 is a graph showing the details of the relative frequency distribution and the cumulative relative frequency distribution of Figure 4. The horizontal axis is fiber length, and the vertical axis is relative frequency and cumulative relative frequency.

[0049] Figure 5 shows that the mode of fiber length is greater than 1000 μm and less than or equal to 1200 μm, and that the median, which corresponds to 50% of the cumulative relative frequency of fiber length, is greater than 1200 μm. In other words, having a median of 1200 μm or more that corresponds to 50% of the cumulative relative frequency of fiber length is one of the characteristics of the resin composition of this disclosure. Having a median of 1200 μm or more of fiber length can be rephrased as having a fiber length of 50% or more of the fibers.

[0050] Figure 6 is a table showing statistical values ​​of the fiber length of the fibers contained in the resin composition of item (5) shown in Figure 3.

[0051] As shown in Figure 6, for the fibers contained in the resin composition of item (5), the number of fibers within the measurement range was 211, the average fiber length was 1503 μm, the maximum fiber length was 5980 μm, and the minimum fiber length was 170 μm. [Explanation of Symbols]

[0052] 10: Washer dryer, 11: Outer tub, 12: Rotating drum, 13: Front door, 20: Vacuum cleaner, 21: Head, 22: Extension pipe, 23: Main unit, 24: Charging stand.

Claims

1. Recycled polypropylene and Contains fibers, The recycled polypropylene includes block polypropylene, The average fiber length of the aforementioned fibers is 1400 μm or more. The resin composition comprises fibers having a fiber length of 1200 μm or more, with a fiber ratio of 50% or more.

2. The resin composition according to claim 1, The bending strength is 65 MPa or higher. The flexural modulus is 3000 MPa or higher. A resin composition having a melt flow rate of 15 g / 10 min or more.

3. The resin composition according to claim 1, A resin composition having a fiber content of 15% by mass or more and 40% by mass or less.

4. The resin composition according to claim 1, The recycled polypropylene is a resin composition derived from household electrical appliances.

5. The resin composition according to claim 1, The aforementioned fibers are a resin composition comprising either virgin fibers or regenerated fibers.

6. The resin composition according to claim 5, The aforementioned fiber is a resin composition comprising either glass fiber or carbon fiber.

7. A resin molded article comprising the resin composition described in claim 1.

8. A resin molded product according to claim 7, A resin molded product, which is an injection-molded product.

9. A resin molded product according to claim 7, A resin molded part that is a component of a washing machine / dryer or a vacuum cleaner.

10. A structure comprising a resin molded product as described in claim 7.

11. A structure according to claim 10, A structure that is a washing machine / dryer or a vacuum cleaner.

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