Foam, master batch, and foam production method and recycling method

Abstract

To provide a foam derived from a recycled resin which solves problems of difficulty of refining and decrease in physical property of air bubbles in a foam using a recycled resin.SOLUTION: A foam contains a recycled polyolefin resin and a cellulose fiber.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a foam, a masterbatch, and a method for producing and recycling the foam.

Background Art

[0002] There is a demand for efforts towards a circular economy that reuses waste plastics as resources. However, foams containing recycled resin have problems such as difficulty in miniaturizing bubbles and deterioration of physical properties due to the inconsistent quality of the recycled resin in the unfoamed state.

[0003] To solve this problem, a method of using virgin resin as a raw material in combination is known, but it is difficult to improve the recycled resin content in the foam containing recycled resin by this method.

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a novel foam containing recycled resin that solves the problems of difficulty in miniaturizing bubbles and deterioration of physical properties in the foam containing recycled resin. Another object is to provide a masterbatch for producing the foam containing the recycled resin, and also to provide a method for producing and recycling the foam containing the recycled resin.

Means for Solving the Problems

[0005] The inventor of the present invention conducted intensive studies to solve the problems of difficulty in miniaturizing bubbles and deterioration of physical properties in the foam containing recycled resin, and as a result, found that a foam containing recycled resin that solves these problems can be obtained by using cellulose fibers. The present invention was completed by further studies based on such findings and includes the following aspects.

[0006] Item 1. A foam containing a recycled polyolefin resin and cellulose fibers. Item 2. The foam according to Item 1, wherein the content of the cellulose fiber in 100% by weight of the foam is 0.01% to 10% by weight. Item 3. The foam according to Item 1 or 2, wherein the average fiber diameter of the cellulose fiber is 1 nm to 100 μm. Item 4. The foam according to any one of Items 1 to 3, wherein the average cell diameter of the foam is 0.1 to 5.0 mm. Item 5. The foam according to any one of Items 1 to 4, wherein the tensile strength of the foam is 14 N / cm 2 or more. Item 6. The foam according to any one of Items 1 to 5, wherein the expansion ratio of the foam is 20 cm 3 / g or more. Item 7. The foam according to any one of Items 1 to 6, wherein the elongation of the foam is 20% or more. Item 8. The foam according to any one of Items 1 to 7, wherein the content of the recycled polyolefin resin in 100% by weight of the foam is 75% by weight or more. Item 9. A masterbatch for producing a foam containing a recycled polyolefin resin, comprising a polyolefin resin and cellulose fibers. Item 10. (A1) A step of obtaining a foam by foaming a raw material containing a masterbatch containing a polyolefin resin and cellulose fibers and an additional polyolefin resin including A method for producing a foam containing a recycled polyolefin resin and cellulose fibers, wherein the polyolefin resin and / or the additional polyolefin resin contained in the masterbatch contains a recycled polyolefin resin. Item 11. (B1) A step of obtaining a foam by foaming a mixture containing a kneaded product containing a foam and / or an unfoamed product containing a recycled polyolefin resin and cellulose fibers and a masterbatch containing a polyolefin resin and cellulose fibers A recycling method for a foam and / or non-foamed body containing a recycled polyolefin resin and cellulose fibers.

Advantages of the Invention

[0007] According to the present invention, a novel foam containing a recycled resin that solves the above problems can be provided. Further, according to the present invention, a masterbatch for producing a foam containing the recycled resin, a method for producing a foam containing the recycled resin, and a recycling method can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] 1. The foam of the present invention The foam of the present invention is a foam containing a recycled polyolefin resin and cellulose fibers. The foam of the present invention is obtained by foaming a raw material containing a masterbatch containing a polyolefin resin and cellulose fibers and an additional polyolefin resin, and the polyolefin resin contained in the masterbatch and / or the additional polyolefin resin may contain a recycled polyolefin resin. In particular, from the viewpoint of increasing the content of the recycled polyolefin resin in the foam, the foam of the present invention is preferably obtained by foaming a raw material containing a masterbatch containing a recycled polyolefin resin and cellulose fibers and an additional polyolefin resin, and more preferably obtained by foaming a raw material containing a masterbatch composed of a recycled polyolefin resin and cellulose fibers and an additional polyolefin resin.

[0010] The recycled polyolefin resin refers to a polyolefin resin obtained by recycling a polyolefin resin in a foamed state and / or an unfoamed state as a recycled raw material. The polyolefin resin to be recycled is not particularly limited, and examples thereof include polyethylene, polypropylene, polybutene, and the like. Polyethylene includes low-density polyethylene (LDPE) and high-density polyethylene (HDPE). In the present invention, the recycled polyolefin resin may be obtained by recycling one or more of the above-mentioned polyolefin resins to be recycled as a recycled raw material. Among them, in the present invention, the recycled polyolefin resin is preferably a polyolefin resin obtained by recycling polyethylene in a foamed state and / or an unfoamed state, and more preferably a polyolefin resin obtained by recycling LDPE.

[0011] The recycled polyolefin resin in the foam of the present invention preferably contains 80% by weight or more of the polyolefin resin, more preferably 85% by weight or more, and even more preferably 90% by weight or more.

[0012] The recycled polyolefin resin in the foam of the present invention may contain components other than the polyolefin resin. The components other than the polyolefin resin are not particularly limited, and examples thereof include components other than the polyolefin resin contained in the polyolefin resin before being recycled. Examples of the components other than the polyolefin resin include pigments, colorants, dispersants, anti-shrinking agents, antioxidants, heat stabilizers, weathering agents, ultraviolet absorbers, flame retardants, inorganic fillers, antibacterial agents, and the like.

[0013] In the foam of the present invention, the content of the recycled polyolefin resin is not particularly limited as long as the foam contains the recycled polyolefin resin. The lower limit of the content of the recycled polyolefin resin in the foam of the present invention can be, for example, 0.01% by weight or more, 0.1% by weight or more, or 1% by weight or more based on 100% by weight of the foam. Further, in the foam of the present invention, by mixing cellulose fibers, the content of the recycled polyolefin resin can be 75% by weight or more, 80% by weight or more, 85% by weight or more, or 90% by weight or more. The upper limit of the content of the recycled polyolefin resin in the foam of the present invention can be, for example, 99.99% by weight or less, 99.95% by weight or less, or 99.9% by weight or less based on 100% by weight of the foam.

[0014] In the foam of the present invention, the cellulose fibers include cellulose nanofibers (CNF) and cellulose microfibers (CMF).

[0015] In the foam of the present invention, the lower limit of the cellulose fiber content may be, for example, 0.01 wt%, 0.05 wt% or 0.1 wt% based on 100 wt% of the foam. From the viewpoint of refining the cells and improving the physical properties, the lower limit of the cellulose fiber content is preferably 0.01 wt%, more preferably 0.05 wt%, and even more preferably 0.1 wt% based on 100 wt% of the foam. Further, the upper limit of the cellulose fiber content may be, for example, 10 wt%, 9 wt%, 8 wt%, 7 wt% or 6 wt% based on 100 wt% of the foam. From the viewpoint of improving the foamability of the foam, the upper limit of the cellulose fiber content is preferably 10 wt%, more preferably 9 wt%, even more preferably 8 wt%, particularly preferably 7 wt%, and most preferably 6 wt% based on 100 wt% of the foam.

[0016] When the cellulose fiber is CNF, the lower limit of the CNF content in the foam of the present invention may be, for example, 0.01 wt%, 0.05 wt% or 0.1 wt% based on 100 wt% of the foam. When the cellulose fiber is CNF, from the viewpoint of refining the cells and improving the physical properties, the lower limit of the CNF content is preferably 0.01 wt%, more preferably 0.05 wt%, and even more preferably 0.1 wt% based on 100 wt% of the foam. Further, when the cellulose fiber is CNF, the upper limit of the CNF content in the foam of the present invention may be, for example, 5 wt%, 4 wt%, 3 wt% or 2 wt% based on 100 wt% of the foam. When the cellulose fiber is CNF, from the viewpoint of improving the foamability of the foam, the upper limit of the CNF content is preferably 5 wt%, more preferably 4 wt%, even more preferably 3 wt%, particularly preferably 2 wt% based on 100 wt% of the foam.

[0017] When the cellulose fiber is CMF, the lower limit of the CMF content in the foam of the present invention may be, for example, 0.01% by weight, 0.05% by weight, or 0.1% by weight based on 100% by weight of the foam. When the cellulose fiber is CMF, from the viewpoints of miniaturization of bubbles and improvement of physical properties, the lower limit of the CMF content in the foam of the present invention is preferably 0.01% by weight, more preferably 0.05% by weight, and even more preferably 0.1% by weight based on 100% by weight of the foam. Further, when the cellulose fiber is CMF, the upper limit of the CMF content in the foam of the present invention may be, for example, 10% by weight, 9% by weight, 8% by weight, 7% by weight, or 6% by weight based on 100% by weight of the foam. When the cellulose fiber is CMF, from the viewpoint of improving the foamability of the foam, the upper limit of the CMF content in the foam of the present invention is preferably 10% by weight, more preferably 9% by weight, even more preferably 8% by weight, particularly preferably 7% by weight, and most preferably 6% by weight based on 100% by weight of the foam.

[0018] In the foam of the present invention, the average fiber diameter of the cellulose fiber is preferably from 1 nm to 100 μm, more preferably from 10 nm to 50 μm, and even more preferably from 20 nm to 25 μm. The average fiber diameter of the cellulose fiber can be determined from an atomic force microscope (AMF) image. Here, the "average fiber diameter" refers to the number-average fiber diameter.

[0019] From the viewpoint of improving the smoothness of the skin surface of the foam, the average cell diameter (average bubble diameter) of the foam of the present invention is preferably from 0.1 to 5.0 mm, more preferably from 0.1 to 3.5 mm, and even more preferably from 0.1 to 2.0 mm.

[0020] The average cell diameter of the foam can be calculated according to the following formula (I). Average cell diameter of the foam = average chord length t × 1.62... Formula (I) In the above formula (I), the average chord length t is represented by the following formula (II). Average chord length t = 25 mm / number of cells c … Formula (II) In the above formula (II), the number of cells c can be measured as follows in accordance with the test method of JIS K 6767:1999. Specifically, at least 5 test pieces of 50 mm × 50 mm × 3 mm are cut out from the foam. Using an electron microscope (Miniscope (registered trademark) TM3030, manufactured by Hitachi High-Tech Corporation), the test pieces are observed at a magnification of 100 times in a low vacuum environment, and the number of cells per 25 mm of the foam is measured.

[0021] The tensile strength of the foam of the present invention is preferably 14 N / cm 2 or more, more preferably 20 N / cm 2 or more, and even more preferably 25 N / cm 2 or more.

[0022] The tensile strength of the foam can be calculated according to the following formula (III) in accordance with the test method of JIS A 9511:2017. Tensile strength = maximum load N until cutting / cross-sectional area of test piece … Formula (III) In the above formula (III), the cross-sectional area of the test piece is represented by the following formula (IV). Cross-sectional area of test piece = width b of test piece × thickness t of test piece … Formula (IV) Specifically, the test piece is attached to a tensile testing device, the test piece is pulled at a tensile speed of 500 mm / min, and the maximum load N until cutting is measured. The shape of the test piece is a dumbbell-shaped test piece with a width of 10 mm and parallel upper and lower surfaces. The tensile strength is measured for 5 test pieces, the maximum and minimum values are excluded, and the average value of 3 pieces is taken and rounded to an integer value.

[0023] The expansion ratio of the foam of the present invention is preferably 20 cm 3 / g or more, more preferably 25 cm 3 / g or more, and even more preferably 30 cm 3 / g or more.

[0024] The expansion ratio of the foam of the present invention can be calculated according to the following formula (V). Expansion ratio = volume V of test piece / mass W of test piece... Formula (V) The test piece has parallel upper and lower surfaces and is in a shape whose volume can be easily calculated. The volume is 15 cm 3 or more. The number of test pieces is three.

[0025] The elongation of the foam of the present invention is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more.

[0026] The elongation of the foam of the present invention can be calculated according to the following formula (VI) in accordance with the test method of JIS K 6767:1999. Elongation = (distance between marks at the time of cutting - distance between marks before the test) / distance between marks before the test × 100... (VI) In the above formula (VI), the distance between marks before the test is 40 mm. Specifically, the test piece is attached to a tensile test device, the test piece is pulled at a tensile speed of 500 mm / min, and the distance between marks at the time of cutting is measured. The shape of the test piece is a dumbbell-shaped test piece with a width of 10 mm and parallel upper and lower surfaces. The tensile strength is measured for five test pieces, the maximum value and the minimum value are excluded, and the average value of the three is taken and rounded to an integer value.

[0027] The foam of the present invention may contain other components other than the recycled polyolefin resin and the cellulose fiber. The other components are not particularly limited, and examples thereof include non-recycled polyolefin resins, pigments, colorants, dispersants, anti-shrinkage agents, antioxidants, heat stabilizers, weathering agents, ultraviolet absorbers, flame retardants, inorganic fillers, antibacterial agents, and the like. The non-recycled polyolefin resin is not particularly limited as long as it is a polyolefin resin that has not been recycled into raw materials, and examples thereof include polyethylene, polypropylene, polybutene, and the like. Polyethylene includes low-density polyethylene (LDPE) and high-density polyethylene (HDPE).

[0028] 2.The masterbatch of the present invention The masterbatch of the present invention is a masterbatch for producing a foam containing a recycled polyolefin resin, which contains a polyolefin resin and cellulose fibers.

[0029] The polyolefin resin contained in the masterbatch of the present invention may contain a recycled polyolefin resin or may be a recycled polyolefin resin. In particular, from the viewpoint of increasing the content of the recycled polyolefin resin in the foam that can be obtained using the masterbatch of the present invention, the polyolefin resin contained in the masterbatch of the present invention preferably contains a recycled polyolefin resin, and more preferably is a recycled polyolefin resin.

[0030] The polyolefin resin contained in the masterbatch of the present invention may be a polyolefin resin containing a recycled polyolefin resin and / or a non-recycled polyolefin resin, or may be a polyolefin resin composed of a recycled polyolefin resin and a non-recycled polyolefin resin, or may be a polyolefin resin consisting of only a recycled polyolefin resin or a non-recycled polyolefin resin.

[0031] When the masterbatch of the present invention contains a recycled polyolefin resin in the polyolefin resin, the content of the recycled polyolefin resin in the polyolefin resin is not particularly limited as long as the polyolefin resin contains the recycled polyolefin resin. The lower limit of the content of the recycled polyolefin resin in the polyolefin resin is, for example, 0.01% by weight, 0.1% by weight, 1% by weight, 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 15% by weight, 20% by weight, 25% by weight, 30% by weight, 35% by weight, 40% by weight, 45% by weight, 50% by weight, 55% by weight, 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80% by weight, 85% by weight, 90% by weight, 95% by weight, 99% by weight or 100% by weight based on 100% by weight of the polyolefin resin. Further, the upper limit of the content of the recycled polyolefin resin in the polyolefin resin is, for example, 0.01% by weight, 0.1% by weight, 1% by weight, 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 15% by weight, 20% by weight, 25% by weight, 30% by weight, 35% by weight, 40% by weight, 45% by weight, 50% by weight, 55% by weight, 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80% by weight, 85% by weight, 90% by weight, 95% by weight, 99% by weight or 100% by weight based on 100% by weight of the polyolefin resin.

[0032] When the masterbatch of the present invention contains a non-renewable polyolefin resin in the polyolefin resin, the content of the non-renewable polyolefin resin in the polyolefin resin is not particularly limited as long as the polyolefin resin contains the non-renewable polyolefin resin. The lower limit of the content of the non-renewable polyolefin resin in the polyolefin resin can be, for example, 0.01 wt%, 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 99 wt% or 100 wt% based on 100 wt% of the polyolefin resin. Also, the upper limit of the content of the non-renewable polyolefin resin in the polyolefin resin can be, for example, 0.01 wt%, 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 99 wt% or 100 wt% based on 100 wt% of the polyolefin resin.

[0033] In particular, from the viewpoint of increasing the content of the recycled polyolefin resin in the foam that can be obtained using the masterbatch of the present invention, the polyolefin resin contained in the masterbatch of the present invention preferably contains a recycled polyolefin resin, and more preferably is a recycled polyolefin resin.

[0034] The content of the polyolefin resin contained in the masterbatch of the present invention is preferably 30 wt% to 99 wt%, more preferably 35 wt% to 95 wt%, and even more preferably 40 wt% to 90 wt% based on 100 wt% of the masterbatch.

[0035] The content of the cellulose fiber contained in the masterbatch of the present invention is preferably 1% by weight to 70% by weight, more preferably 5% by weight to 65% by weight, and even more preferably 10% by weight to 60% by weight based on 100% by weight of the masterbatch.

[0036] In the masterbatch of the present invention, the ratio of the polyolefin resin to the cellulose fiber (polyolefin resin: cellulose fiber) is preferably 99:1 to 3:7, more preferably 95:5 to 7:13, and even more preferably 9:1 to 4:6.

[0037] The method for obtaining the masterbatch of the present invention is not particularly limited, and it can be obtained by mixing a polyolefin resin and a cellulose fiber by uniformly dispersing the cellulose fiber in the polyolefin resin by heat melting and kneading, for example, using a single-screw kneader, a multi-screw kneader, a kneader, or the like.

[0038] The masterbatch of the present invention may contain other components other than the polyolefin resin and the cellulose fiber. The other components are not particularly limited, and examples thereof include pigments, colorants, dispersants, anti-shrinkage agents, antioxidants, heat stabilizers, weathering agents, ultraviolet absorbers, flame retardants, inorganic fillers, antibacterial agents, and the like.

[0039] 3. The manufacturing method of the foam of the present invention The method for producing the foam of the present invention is (A1) A step of obtaining a foam by foaming a raw material containing a masterbatch containing a polyolefin resin and a cellulose fiber and an additional polyolefin resin and the polyolefin resin and / or the additional polyolefin resin contained in the masterbatch contains a recycled polyolefin resin, and it is a method for producing a foam containing a recycled polyolefin resin and a cellulose fiber.

[0040] The polyolefin resin contained in the masterbatch of step (A1) may be a polyolefin resin containing a recycled polyolefin resin and / or a non-recycled polyolefin resin, or may be a polyolefin resin composed of a recycled polyolefin resin and a non-recycled polyolefin resin, or may be a polyolefin resin consisting only of a recycled polyolefin resin or a non-recycled polyolefin resin.

[0041] In step (A1), when the polyolefin resin contained in the masterbatch contains a recycled polyolefin resin, the content of the recycled polyolefin resin in the polyolefin resin is not particularly limited as long as the polyolefin resin contains the recycled polyolefin resin. The lower limit of the content of the recycled polyolefin resin in the polyolefin resin contained in the masterbatch can be, for example, 0.01 wt%, 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 99 wt% or 100 wt% based on 100 wt% of the polyolefin resin. Also, the upper limit of the content of the recycled polyolefin resin in the polyolefin resin can be, for example, 0.01 wt%, 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 99 wt% or 100 wt% based on 100 wt% of the polyolefin resin.

[0042] In step (A1), when the additional polyolefin resin contains a non-renewable polyolefin resin, the content of the non-renewable polyolefin resin in the additional polyolefin resin is not particularly limited as long as the additional polyolefin resin contains the non-renewable polyolefin resin. The lower limit of the content of the non-renewable polyolefin resin in the additional polyolefin resin can be, for example, 0.01 wt%, 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 99 wt% or 100 wt% based on 100 wt% of the polyolefin resin. Also, the upper limit of the content of the non-renewable polyolefin resin in the polyolefin resin can be, for example, 0.01 wt%, 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 99 wt% or 100 wt% based on 100 wt% of the polyolefin resin.

[0043] In particular, from the viewpoint of increasing the content of the renewable polyolefin resin in the foam, the polyolefin resin contained in the masterbatch of step (A1) preferably contains a renewable polyolefin resin, and more preferably is a renewable polyolefin resin.

[0044] In step (A1), the content of the polyolefin resin contained in the masterbatch is preferably 30 wt% to 99 wt%, more preferably 35 wt% to 95 wt%, and even more preferably 40 wt% to 90 wt% based on 100 wt% of the masterbatch.

[0045] In step (A1), the content of the cellulose fiber contained in the masterbatch is preferably 1 wt% to 70 wt%, more preferably 5 wt% to 65 wt%, and even more preferably 10 wt% to 60 wt% based on 100 wt% of the masterbatch.

[0046] In step (A1), the content ratio of the polyolefin resin to the cellulose fiber contained in the masterbatch (polyolefin resin:cellulose fiber) is preferably 99:1 to 3:7, more preferably 95:5 to 7:13, and even more preferably 9:1 to 4:6.

[0047] In step (A1), examples of the method for obtaining the masterbatch containing the polyolefin resin and the cellulose fiber include the methods described above.

[0048] In step (A1), the additional polyolefin resin may be a polyolefin resin containing a recycled polyolefin resin and / or a non-recycled polyolefin resin, or a polyolefin resin composed of a recycled polyolefin resin and a non-recycled polyolefin resin, or a polyolefin resin consisting only of a recycled polyolefin resin or a non-recycled polyolefin resin.

[0049] In process (A1), when the additional polyolefin resin contains recycled polyolefin resin, the content of the recycled polyolefin resin in the additional polyolefin resin is not particularly limited as long as the additional polyolefin resin contains recycled polyolefin resin. The lower limit of the content of the recycled polyolefin resin in the additional polyolefin resin can be, for example, 0.01 wt%, 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 99 wt% or 100 wt% based on 100 wt% of the polyolefin resin. Also, the upper limit of the content of the recycled polyolefin resin in the polyolefin resin can be, for example, 0.01 wt%, 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 99 wt% or 100 wt% based on 100 wt% of the polyolefin resin.

[0050] In step (A1), when the additional polyolefin resin contains a non-renewable polyolefin resin, the content of the non-renewable polyolefin resin in the additional polyolefin resin is not particularly limited as long as the additional polyolefin resin contains the non-renewable polyolefin resin. The lower limit of the content of the non-renewable polyolefin resin in the additional polyolefin resin can be, for example, 0.01 wt%, 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 99 wt% or 100 wt% based on 100 wt% of the polyolefin resin. Also, the upper limit of the content of the non-renewable polyolefin resin in the polyolefin resin can be, for example, 0.01 wt%, 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 99 wt% or 100 wt% based on 100 wt% of the polyolefin resin.

[0051] In step (A1), the foaming method is not particularly limited, and examples thereof include physical foaming using a physical foaming agent or chemical foaming using a chemical foaming agent. Examples of the physical foaming agent include inorganic physical foaming agents (e.g., air, carbon dioxide gas, nitrogen gas, water, etc.), organic physical foaming agents (e.g., butane, pentane, hexane, dichloromethane, dichloroethane, etc.), and supercritical fluids (e.g., carbon dioxide gas, nitrogen gas, etc. in a supercritical fluid state). Examples of chemical foaming include batch foaming, atmospheric pressure secondary foaming, etc. Examples of the chemical foaming agent include organic foaming agents (e.g., azodicarbonamide (ADCA), N,N'-dinitrosopentamethylenetetramine, 4,4'-oxybis(benzenesulfonylhydrazide), diphenylsulfone-3,3'-disulfonylhydrazide, p-toluenesulfonyl semicarbazide, trihydrazinotriazine, azobisisobutyronitrile, etc.), inorganic foaming agents (e.g., a mixture of a polycarboxylic acid (e.g., citric acid, oxalic acid, fumaric acid, phthalic acid, malic acid, tartaric acid, cyclohexane-1,2-dicarboxylic acid, camphoric acid, ethylenediaminetetraacetic acid, triethylenetetraminehexaacetic acid, nitrilotriacetic acid, etc.) and an inorganic carbonate compound (e.g., sodium bicarbonate, sodium aluminum bicarbonate, potassium bicarbonate, ammonium bicarbonate, ammonium carbonate, etc.)), salts of polycarboxylic acids (e.g., sodium dihydrogen citrate, potassium oxalate, etc.), etc.).

[0052] 4. The recycling method of the foam of the present invention The recycling method of the foam of the present invention is (B1) A step of foaming a mixture containing a kneaded product containing a foam and / or unfoamed body containing a recycled polyolefin resin and cellulose fiber and a masterbatch containing a polyolefin resin and cellulose fiber to obtain a foam It is a recycling method of a foam and / or unfoamed body containing a recycled polyolefin resin and cellulose fiber, which includes

[0053] In step (B1), the foam and / or non-foam containing the recycled polyolefin resin and cellulose fiber is not particularly limited, and may be, for example, the foam and / or non-foam obtained by producing the foam of the present invention.

[0054] In step (B1), the method for obtaining a kneaded product containing a foam and / or non-foam containing a recycled polyolefin resin and cellulose fiber is not particularly limited. For example, it can be obtained by pulverizing the foam and / or non-foam and then melt-kneading with an extruder or the like and then pelletizing into solid pellets.

[0055] In step (B1), when both the foam and the non-foam are contained in the kneaded product, the content ratio thereof (foam: non-foam) is not particularly limited, and may be, for example, 0.1:99.9 to 99.9:0.1, 1:99 to 99:1, etc.

[0056] The masterbatch containing the polyolefin resin and cellulose fiber in step (B1) may have the same characteristics as the masterbatch used in the above-described method for producing the foam of the present invention.

[0057] In step (B1), the method for obtaining a mixture containing the kneaded product and the masterbatch is not particularly limited, and examples thereof include a method performed by mixing by supply to a foaming device, stirring and mixing, etc.

[0058] As the foaming method in step (B1), the methods described above can be mentioned.

[0059] The lower limit of the cellulose fiber content in the foam obtained in step (B1) may be 1 wt%, 1.5 wt%, or 2 wt% based on 100 wt% of the foam. From the perspective of obtaining a desired foam, the lower limit of the cellulose fiber content in the foam obtained in step (B1) is preferably 1 wt%, more preferably 1.5 wt%, and even more preferably 2 wt% based on 100 wt% of the foam. Also, the upper limit of the cellulose fiber content in the foam obtained in step (B1) may be 10 wt%, 9 wt%, 8 wt%, 7 wt%, or 6 wt% based on 100 wt% of the foam. From the perspective of improving the foamability of the foam, the upper limit of the cellulose fiber content in the foam obtained in step (B1) is preferably 10 wt%, more preferably 9 wt%, even more preferably 8 wt%, particularly preferably 7 wt%, and most preferably 6 wt% based on 100 wt% of the foam.

Examples

[0060] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

[0061] <Example 1. Production of Foam> (1-1) Manufacture of masterbatch for foam production 80 wt% of low-density polyethylene (recycled low-density polyethylene (recycled LDPE) (Toyotec LD (miscellaneous) 3-1322-00, manufactured by Toyo Chemical Co., Ltd.), or non-recycled low-density polyethylene (non-recycled LDPE) (F234, manufactured by Ube Maruzen Polyethylene Co., Ltd.)) and 20 wt% of cellulose fiber (N-made, C-made, NK-made, or P-made) were mixed to produce a masterbatch (MB) for foam production. The produced masterbatch is shown in Table 1.

Table 1

[0062] (1-2) Manufacture of foam containing recycled polyolefin resin Each of the manufactured masterbatches (No. 1 to No. 5) or talc (SS-11-20, manufactured by Sumika Color Co., Ltd.), non-renewable low-density polyethylene (non-renewable LDPE) (F234, manufactured by Ube Maruzen Polyethylene Co., Ltd.), and an anti-shrinkage agent (Lichemaster (registered trademark) ELB-347, manufactured by Riken Vitamin Co., Ltd.) were supplied to a 65 mmφ single-screw extruder (AE-01, manufactured by HANSUNG PLASTIC Co., Ltd.) at the ratios shown in Table 2 below. After melting and kneading these components at 130°C or higher, a blowing agent (butane gas) was infiltrated and dissolved under pressure, and the pressure was released to atmospheric pressure to vaporize the blowing agent to produce a foam (Examples 1 to 4, Comparative Examples 1 and 2). Also, without masterbatch and talc, a foam was produced in the same manner as above from non-renewable LDPE (F234, manufactured by Ube Maruzen Polyethylene Co., Ltd.) and an anti-shrinkage agent (Lichemaster (registered trademark) ELB-347, manufactured by Riken Vitamin Co., Ltd.) at the ratios shown in Table 2 below (Comparative Example 3). Furthermore, without masterbatch, a foam was produced in the same manner as above from non-renewable LDPE (F234, manufactured by Ube Maruzen Polyethylene Co., Ltd.), recycled LDPE (Toyotech LD (miscellaneous) 3-1322-00, manufactured by Toyo Chemical Co., Ltd.), an anti-shrinkage agent (Lichemaster (registered trademark) ELB-347, manufactured by Riken Vitamin Co., Ltd.), and optionally talc (SS-11-20, manufactured by Sumika Color Co., Ltd.) (Comparative Examples 4 and 5).

Table 2

[0063] (1-3) Physical property evaluation of foam containing recycled polyolefin resin Table 3 shows the results of evaluating the physical properties (foaming moldability, average cell diameter, foaming ratio, tensile strength, and elongation) of the foam obtained in (1-2). Also, the cross-section of the foam obtained in (1-2) is shown in Figure 1.

[0064] The foam formability was evaluated as good (indicated by "○" in Table 3) when the raw material components of the foam could flow smoothly inside the circular die (round die) provided at the discharge part of the extruder, i.e., there was no risk of unevenness on the surface of the foam, such as a decrease in the smoothness of the surface (skin surface).

[0065] The average cell diameter was calculated according to the following formula (I). Average cell diameter = average chord length t × 1.62 … Formula (I) In the above formula (I), the average chord length t is represented by the following formula (II). Average chord length t = 25 mm / number of cells c … Formula (II) In the above formula (II), the number of cells c was measured as follows in accordance with the test method of JIS K 6767:1999. Specifically, at least 5 test pieces of a minimum size of 50 mm × 50 mm × 3 mm were cut out from the foam, and the test pieces were observed at a magnification of 100 times in a low vacuum environment using an electron microscope (Miniscope (registered trademark) TM3030, manufactured by Hitachi High-Tech Corporation), and the number of cells per 25 mm of the foam was measured.

[0066] The expansion ratio was calculated according to the following formula (V). Expansion ratio = volume V of test piece / mass W of test piece … Formula (V) The test pieces had parallel upper and lower surfaces and were of a shape whose volume could be easily calculated, and those with a volume of 15 cm3 or more were used. The number of test pieces was 3.

[0067] The tensile strength was calculated according to the following formula (III) in accordance with the test method of JIS A 9511:2017. Tensile strength σt = maximum load N until cutting / cross-sectional area of test piece … Formula (III) In the above formula (III), the cross-sectional area of the test piece is represented by the following formula (IV). Cross-sectional area of test piece = width b of test piece × thickness t of test piece … Formula (IV) The test piece was attached to a tensile testing apparatus, and the test piece was pulled at a tensile speed of 500 mm / min, and the maximum load N until cutting was measured. The shape of the test piece was a dumbbell-shaped test piece with a width of 10 mm and parallel upper and lower surfaces. The tensile strength was measured for 5 test pieces, excluding the maximum and minimum values, and taken as the average value of 3 pieces, and rounded to an integer value.

[0068] Elongation was calculated according to the following formula (VI) in accordance with the test method of JIS K 6767:1999. Elongation = (distance between gauge marks at the time of cutting - distance between gauge marks before the test) / distance between gauge marks before the test × 100…(VI) In the above formula (VI), the distance between gauge marks before the test was 40 mm. Specifically, the test piece was attached to a tensile testing apparatus, and the test piece was pulled at a tensile speed of 500 mm / min, and the distance between gauge marks at the time of cutting was measured. The shape of the test piece was a dumbbell-shaped test piece with a width of 10 mm and parallel upper and lower surfaces. The tensile strength was measured for 5 test pieces, excluding the maximum and minimum values, and taken as the average value of 3 pieces, and rounded to an integer value.

[0069]

Table 3

[0070] The foams containing recycled polyolefin resin and cellulose fiber (Examples 1 to 4) had an average cell diameter equal to or smaller than that of the foams not containing recycled polyolefin resin (Comparative Examples 1 to 3) or the foams not containing cellulose fiber (Comparative Examples 4 and 5) (Figure 1, Table 3). Also, other physical properties (foaming ratio, tensile strength, and elongation) of the foams containing recycled polyolefin resin and cellulose fiber (Examples 1 to 4) were comparable to those of the foams not containing recycled polyolefin resin (Comparative Examples 1 to 3) or the foams not containing cellulose fiber (Comparative Examples 4 and 5) (Table 3). From these results, it was found that by incorporating cellulose fiber into the foam, the refinement of the bubbles of the foam containing recycled polyolefin resin was promoted, and the decrease in physical properties due to the inclusion of recycled polyolefin resin was suppressed.

[0071] In addition, the foamability was good in any of the foams of Examples 1 to 4 (Table 3). (1-4) Manufacture of foam containing high-content recycled polyolefin resin In order to confirm that the effect of promoting the refinement of the bubbles of the foam and the effect of suppressing the deterioration of the physical properties by including cellulose fibers in the foam containing the recycled polyolefin resin shown in the above (1-3) are also shown in the foam containing a higher content of the recycled polyolefin resin, a foam containing a higher content of the recycled polyolefin resin was produced.

[0072] The masterbatch (No. 2) or talc (SS-11-20, manufactured by Sumika Color Co., Ltd.) produced in the above (1-1), recycled LDPE (Toyotec LD (miscellaneous) 3-1322-00 (manufactured by Toyo Chemical Co., Ltd.) or Toyotec LD (black) 3-1321-00 (manufactured by Toyo Chemical Co., Ltd.)) and / or non-recycled LDPE (F234, manufactured by Ube Maruzen Polyethylene Co., Ltd.), and an anti-shrinkage agent (Lichemaster (registered trademark) ELB-347, manufactured by Riken Vitamin Co., Ltd.) were supplied to a 65 mmφ single-screw extruder (AE-01, manufactured by HANSUNG PLASTIC Co., Ltd.) at the ratios shown in Table 4 below, and a foam was produced in the same manner as in the above (1-2).

[0073]

Table 4

[0074] (1-5) Physical property evaluation of foam containing high-content recycled polyolefin resin Table 5 shows the results of evaluating the physical properties (foamability, average cell diameter, foaming ratio, tensile strength, and elongation) of the foam obtained in (1-4). The evaluation methods for each physical property are as described above. In addition, the cross-section of the foam obtained in (1-4) is shown in Figure 2.

[0075]

Table 5

[0076] The foams containing recycled polyolefin resin and cellulose fiber (Examples 5 to 7) had a smaller average cell diameter than the foam not containing recycled polyolefin resin and cellulose fiber (Comparative Example 6) (Fig. 2, Table 5). Further, other physical properties (foaming ratio, tensile strength and elongation) of the foams containing recycled polyolefin resin and cellulose fiber (Examples 5 to 7) were comparable to those of the foam not containing recycled polyolefin resin and cellulose fiber (Comparative Example 6) (Table 5). Furthermore, when comparing Example 5 and Comparative Example 7 with comparable recycled polyolefin resin contents, the average cell diameter of Example 5 containing cellulose fiber was smaller than that of Comparative Example 7 not containing cellulose fiber, and other physical properties (foaming ratio, tensile strength and elongation) of Example 5 containing cellulose fiber were comparable to those of Comparative Example 7 not containing cellulose fiber (Table 5). From these results, it was shown that even in foams containing a higher content of recycled polyolefin resin, the effect of promoting the refinement of bubbles and the effect of suppressing the deterioration of physical properties of the foams containing recycled polyolefin resin by including cellulose fiber were exhibited.

[0077] In addition, the foamability was good in any of the foams (Table 5).

[0078] <Example 2. Recycling of Foam Containing Recycled Polyolefin Resin and Cellulose Fiber> (2-1) Manufacture of recycled polyolefin resin using foam and unfoamed resin as raw materials After pulverizing the foams containing recycled LDPE and cellulose fibers (Example 2 and Comparative Example 1), they were melt-kneaded using an extruder or the like (a kneader, RPF manufacturing equipment) and then pelletized into solid pellets. Also, the unfoamed materials discharged in the manufacturing process of the above-mentioned (1-2) foams (masterbatches and non-recycled LDPE used in the production of the foams of Example 2 and Comparative Example 1, in the unfoamed state) were pulverized and then melt-kneaded using an extruder or the like (a kneader, RPF manufacturing equipment) and pelletized into solid pellets. Here, since these solid-pelletized recycled polyolefin resins (recycled LDPE) contained less than 1% cellulose fibers, they are distinguished from the commercially available recycled LDPE without cellulose fibers (Toyotec LD (miscellaneous) 3-1322-00 (manufactured by Toyo Chemical Co., Ltd.) or Toyotec LD (black) 3-1321-00 (manufactured by Toyo Chemical Co., Ltd.)) used in the above experiments and are referred to as "recycled polyolefin resin pellets" or "recycled LDPE pellets".

[0079] (2-2) Manufacture of foam The recycled LDPE pellets pelletized in the above (2-1) (containing approximately 5 wt% and approximately 95 wt% of foam-derived recycled LDPE pellets and unfoamed material-derived recycled LDPE pellets, respectively, based on 100 wt% of the recycled LDPE pellets) were supplied to a 65 mmφ single-screw extruder (AE-01, manufactured by HANSUNG PLASTIC Co., Ltd.) at the ratios shown in Table 6 below, together with the masterbatch (No. 2) manufactured in (1-1) of Example 1 or talc (SS-11-20, manufactured by Sumika Color Co., Ltd.) as the case may be, and foams were manufactured in the same manner as in the above (1-2).

[0080]

Table 6

[0081] (2-3) Physical property evaluation of foam Table 7 shows the results of evaluating the physical properties (foaming moldability, average cell diameter, foaming ratio, tensile strength, and elongation) of each foam obtained in (2-2). The evaluation methods for each physical property are as described above. Also, the cross-sections of each foam obtained in (2-2) are shown in Figure 3.

[0082]

Table 7

[0083] Using the foam containing the recycled polyolefin resin and cellulose fibers and the recycled polyolefin resin pellets obtained from the unfoamed resin discharged in the manufacturing process of the foam as raw materials, the foam could be manufactured again. From these results, it was shown that the foam containing recycled LDPE and cellulose fibers is recyclable.

[0084] Also, the average cell diameter of the foam manufactured using the masterbatch (Example 8) was smaller than that of the foam manufactured without using the masterbatch (Examples 9 and 10) (FIG. 3 and Table 7). Furthermore, other physical properties (foaming ratio, tensile strength, and elongation) of the foam manufactured using the masterbatch (Example 8) were comparable to those of the foam manufactured without using the masterbatch (Examples 9 and 10) (Table 7). From these results, it was shown that in the foam manufactured using the recycled polyolefin resin pellets obtained from the unfoamed resin discharged in the manufacturing process of the foam containing the recycled polyolefin resin and cellulose fibers as raw materials, the effect of promoting the refinement of the bubbles of the foam and the effect of suppressing the deterioration of physical properties are achieved by using the masterbatch containing cellulose fibers.

[0085] In addition, the foamability was good in all foams (Table 7).

Claims

1. A foam comprising a recycled polyolefin resin and cellulose fibers.

2. The foam according to claim 1, wherein the content of the cellulose fibers in 100% by weight of the foam is 0.01% to 10% by weight.

3. The foam according to claim 1 or 2, wherein the average fiber diameter of the cellulose fibers is 1 nm to 100 μm.

4. The foam according to claim 1 or 2, wherein the average cell diameter of the foam is 0.1 to 5.0 mm.

5. The foam according to claim 1 or 2, wherein the tensile strength of the foam is 14 N / cm ２ or more.

6. The foam according to claim 1 or 2, wherein the expansion ratio of the foam is 20 cm ３ / g or more.

7. The foam according to claim 1 or 2, wherein the elongation of the foam is 20% or more.

8. The foam according to claim 1 or 2, wherein the content of the recycled polyolefin resin in 100% by weight of the foam is 75% by weight or more.

9. A masterbatch for producing a foam containing a recycled polyolefin resin, comprising a polyolefin resin and cellulose fibers.

10. A step of obtaining a foam by foaming a raw material containing (A1) a masterbatch containing a polyolefin resin and cellulose fibers and an additional polyolefin resin and A method for producing a foam containing a recycled polyolefin resin and cellulose fibers, wherein the polyolefin resin and / or the additional polyolefin resin contained in the masterbatch contains a recycled polyolefin resin.

11. A step of foaming a mixture containing a kneaded product containing a foam and / or an unfoamed product containing a recycled polyolefin resin and cellulose fibers and a masterbatch containing a polyolefin resin and cellulose fibers to obtain a foam A recycling method for a foam and / or an unfoamed product containing a recycled polyolefin resin and cellulose fibers, which comprises the above step

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