Polyolefin resin composition, recycled carbon fiber reinforced resin molded body, method for producing recycled carbon fiber reinforced resin pellets, and method for producing recycled carbon fiber reinforced resin molded body

Abstract

To provide a polyolefin resin composition capable of obtaining a molding excellent in quality using recycled carbon fibers; a recycled carbon fiber reinforcement resin molding; a method for manufacturing a recycled carbon fiber reinforcement resin pellet; and a method for manufacturing the recycled carbon fiber reinforcement resin molding.SOLUTION: A polyolefin resin composition includes a polyolefin resin, recycled carbon fibers and an imine modified polyolefin resin; a recycled carbon fiber reinforcement resin molding consists of the polyolefin resin composition; a method for manufacturing a recycled carbon fiber reinforcement resin pellet comprises kneading the recycled carbon fibers with the polyolefin resin and the imine modified polyolefin resin by a kneading extruder and extruding the mixture from the kneading extruder to form a pellet; and a method for manufacturing a molding includes manufacturing the molding by any of injection molding, extrusion molding and blow molding using the recycled carbon fiber reinforcement resin pellet.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polyolefin resin composition containing recycled carbon fiber, a recycled carbon fiber reinforced resin molded product, a method for producing recycled carbon fiber reinforced resin pellets, and a method for producing a recycled carbon fiber reinforced resin molded product. [Background technology]

[0002] Carbon fiber reinforced resin moldings are lightweight and highly rigid, and are therefore used in a variety of fields, including automobile and aircraft parts, and housings for portable devices such as laptop computers.

[0003] As the amount of carbon fiber reinforced resin moldings used increases, the amount of carbon fiber reinforced resin moldings discarded after use also increases, and there is a demand for their reuse. As one method for reusing carbon fiber reinforced resin moldings, a method for obtaining recycled carbon fiber from waste carbon fiber reinforced resin moldings has been proposed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-64219 [Patent Document 2] Japanese Patent Application Publication No. 7-33904 Summary of the Invention [Problem to be solved by the invention]

[0005] However, recycled carbon fiber reinforced resin moldings using recycled carbon fibers have the problem of being inferior in physical properties to carbon fiber reinforced resin moldings using virgin (unused) carbon fibers.

[0006] The present invention has been made in consideration of the above points, and aims to provide a polyolefin resin composition that can obtain a molded product of good quality using recycled carbon fibers, a recycled carbon fiber reinforced resin molded product, a method for producing recycled carbon fiber reinforced resin pellets, and a method for producing a recycled carbon fiber reinforced resin molded product. [Means for solving the problem]

[0007] First Aspect The present invention relates to a polyolefin resin composition comprising a polyolefin resin, recycled carbon fibers, and an imine-modified polyolefin resin.

[0008] Second Aspect teeth, First Aspect The imine-modified polyolefin resin accounts for 10 to 50% by weight of the recycled carbon fibers.

[0009] Third Aspect teeth, First Aspect or Second Aspect The recycled carbon fiber is contained in an amount of 5 to 40 parts by weight relative to 100 parts by weight of the polyolefin resin.

[0010] Fourth Aspect teeth, First Aspect from Third Aspect Either Aspects of The recycled carbon fiber is a chopped recycled carbon fiber or a milled recycled carbon fiber.

[0011] Fifth Aspect teeth, First Aspect from Fourth Aspect Either Aspects of The recycled carbon fiber is a pyrolysis product of waste carbon fiber reinforced resin.

[0012] Sixth Aspect teeth, First Aspect from Fifth Aspect Either Aspects of The present invention relates to a recycled carbon fiber reinforced resin molding comprising the polyolefin resin composition described in the above item 1.

[0013] Seventh aspect The present invention relates to a method for producing recycled carbon fiber reinforced resin pellets, which comprises kneading recycled carbon fibers together with a polyolefin resin and an imine-modified polyolefin resin in a kneading extruder, and extruding the kneaded mixture from the kneading extruder to form pellets.

[0014] Eighth aspect The present invention relates to a method for producing a recycled carbon fiber reinforced resin molded article, characterized in that a molded article is obtained by injection molding, extrusion molding, or blow molding using recycled carbon fiber reinforced resin pellets obtained from a polyolefin resin composition containing a polyolefin resin, recycled carbon fiber, and an imine-modified polyolefin resin. [Effects of the Invention]

[0015] The polyolefin resin composition obtained by the present invention contains a polyolefin resin, recycled carbon fiber, and an imine-modified polyolefin resin, and therefore, despite the use of recycled carbon fiber, it is possible to obtain molded articles of good quality. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a table showing the formulations and physical properties of polyolefin resin compositions of Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0017] The polyolefin resin composition, the recycled carbon fiber reinforced resin molded product, the method for producing recycled carbon fiber reinforced resin pellets, and the method for producing recycled carbon fiber reinforced resin molded product according to the present invention will be described below. The polyolefin resin composition of the present invention comprises a polyolefin resin, recycled carbon fibers, and an imine-modified polyolefin resin. Examples of polyolefin resins include polypropylene resin, low-density polyethylene (LDPE), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer resin, ethylene-propylene copolymer, ethylene-butene copolymer, copolymer of ethylene with methyl, ethyl, propyl or butyl acrylate, chlorinated products thereof, mixtures thereof, and mixtures thereof with isotactic polypropylene or atactic polypropylene. Particularly preferred polyolefin resins are polypropylene and polyethylene.

[0018] The recycled carbon fiber is preferably a pyrolysis product obtained by heat-treating waste carbon fiber reinforced resin. Waste carbon fiber reinforced resin is a waste carbon fiber reinforced resin (CFRP) molded product made of carbon fiber and resin. The heat treatment for obtaining recycled carbon fiber from waste carbon fiber reinforced resin involves heating the waste carbon fiber reinforced resin to convert the resin into a carbonized product, and then oxidatively decomposing the carbonized product to obtain carbon fiber (recycled carbon fiber), and this is a well-known processing technique.

[0019] The recycled carbon fiber may be either chopped recycled carbon fiber (preferably 1 to 15 mm in length) or milled recycled carbon fiber. Chopped recycled carbon fiber has a smaller linear expansion coefficient and less stretchability than milled recycled carbon fiber. On the other hand, milled recycled carbon fiber has a better appearance (smoothness) than chopped recycled carbon fiber.

[0020] The amount of recycled carbon fiber blended is preferably 5 to 40 parts by weight, more preferably 5 to 10 parts by weight, per 100 parts by weight of polyolefin resin. If the amount of recycled carbon fiber blended is too small, the rigidity of the molded body will be low, and conversely, if the amount is too large, the moldability of the molded body will be reduced. Virgin carbon fiber may also be used in combination with the recycled carbon fiber.

[0021] Imine-modified polyolefin resins are obtained by grafting a polyimide compound containing many imino groups onto a polyolefin in the presence of a radical generator. Examples of polyolefins that serve as the base for the polyimide compound include polyethylene, polypropylene, poly-1-butene, and polyisobutylene.

[0022] By blending an imine-modified polyolefin resin into a polyolefin resin composition, the melt tension limit speed value during melt extrusion of the polyolefin resin composition increases, thereby improving the appearance (surface smoothness) of the molded article. The melt tension limit speed is the maximum speed at which the resin breaks when taken at an increased speed during melt extrusion, and is measured according to JIS K7199. The higher the melt tension limit speed value, the less likely the melt will burst, resulting in better surface smoothness of the resulting molded article. The blending amount of the imine-modified polyolefin resin is preferably 10 to 50% by weight of the recycled carbon fiber. If the blending amount of the imine-modified polyolefin resin is too small, the smoothness and impact strength of the molded product will be deteriorated.

[0023] The polyolefin resin composition of the present invention is made into recycled carbon fiber reinforced resin pellets and used to produce recycled carbon fiber reinforced resin molded articles. Recycled carbon fiber reinforced resin pellets can be produced by kneading recycled carbon fibers together with polyolefin resin and imine-modified polyolefin resin in a kneading extruder, extruding the kneaded mixture into strands, passing the strands through an underwater cooling tank to cool and harden them, and cutting the strands into pellets with a pelletizer. The resin pelletization is a known method.

[0024] The recycled carbon fiber reinforced resin moldings using the polyolefin resin composition of the present invention are produced by any of injection molding, extrusion molding, and blow molding, and a molding method is adopted depending on the intended use of the molding.

[0025] In injection molding, the recycled carbon fiber reinforced resin pellets are placed in an injection molding machine and melted, and the molten resin is injected into the cavity of a mold to form a cavity-shaped recycled carbon fiber reinforced resin molded body, which is then removed from the mold.

[0026] In extrusion molding, the recycled carbon fiber reinforced resin pellets are fed into an extruder and melted, and the molten resin is extruded through a die to form a recycled carbon fiber reinforced resin molding consisting of a die-shaped long product.

[0027] In blow molding, the recycled carbon fiber reinforced resin pellets are fed into an extruder and melted, and a cylindrical parison is extruded from the head. The parison is then sandwiched inside a blow mold, and gas is blown into the parison to expand it to the shape of the inner surface of the mold, forming a hollow recycled carbon fiber reinforced resin molded body, which is then removed from the mold.

[0028] In addition, blow molding may also be a method in which two sheet-like parisons formed by extruding a sheet instead of a cylindrical parison are sandwiched between a blow mold and gas is blown between the two sheet-like parisons to inflate them to the shape of the inner surface of the mold. [Example]

[0029] The polyolefin resin compositions of each Example and Comparative Example, each having the formulation shown in Figure 1, were melt-kneaded in a kneading extruder (product name: KTX-30, manufactured by Kobe Steel), extruded into an underwater cooling layer in the form of strands with a diameter of 3 mm, and cut into lengths of 3 to 4 mm using a pelletizer (product name: Strand Cutter, manufactured by Tanaka Co., Ltd.) to produce pellets of each Example and Comparative Example. The melt-kneading conditions were barrel and die temperatures of 200°C, screw rotation speed of 400 rpm, and discharge rate of 20 kg / h.

[0030] The raw materials used are shown below. Polyethylene: High-density polyethylene (HDPE), product name: Hi-Zex 5000H, manufactured by Prime Polymer Co., Ltd. Recycled carbon fiber (chopped): Recycled carbon fiber with a fiber length of 10 mm or less, made from the pyrolysis product of waste carbon fiber reinforced resin. Product name: Chopped recycled CF fiber, manufactured by Carbon Fiber Recycle Industry Co., Ltd. Made Recycled carbon fiber (milled): Recycled carbon fiber with an average diameter of 25 μm, made from the pyrolysis product of waste carbon fiber reinforced resin. Product name: Milled recycled CF fiber, manufactured by Carbon Fiber Recycle Industry Co., Ltd. Imine-modified polyolefin resin: Product name: Admer (registered trademark) IP, manufactured by Mitsui Chemicals, Inc. Acid-modified polyolefin resin: Maleic acid-modified polyolefin, product name: Umex, manufactured by Sanyo Chemical Industry Co., Ltd.

[0031] The pellets of each example and comparative example were fed into an extrusion molding machine (product name: GS90, manufactured by Ikegai Co., Ltd.) and extrusion-molded to produce a tubular molded article having an outer diameter of 30 mm and an inner diameter of 25 mm under the following molding conditions: die temperature 200°C, screw rotation speed 30 rpm, and take-up speed 2.0 m / min.

[0032] For each example and comparative example, Charpy impact strength (with notch) was measured as a mechanical property, and melt tension limit speed and linear expansion coefficient (20°C→60°C) were measured as molding evaluations.

[0033] The Charpy impact strength (notched) was measured by feeding the pellets of each example and comparative example into a thermoplastic injection molding machine to prepare a notched test piece sample as specified in JIS K7111, and measuring the sample in accordance with JIS K7111.

[0034] The melt tension limit speed was measured based on JIS K7199 under the measurement conditions of a temperature of 200°C and an extrusion speed of 10 m / min. The melt tension limit speed is the take-up speed at which breakage occurs due to accelerated take-up during melt extrusion of the resin. The higher the limit speed, the less likely the molten resin will break, resulting in a better appearance (surface smoothness) of the molded product. When the measurement result of the melt tension limit speed was less than 9 m / min, the appearance (surface smoothness) evaluation was rated as "×", when it was 9 to 12 m / min, it was rated as "△", when it was 12 to 18 m / min, it was rated as "〇", and when it was 18 m / min or more, it was rated as "◎".

[0035] The linear expansion coefficient was measured by storing a 1000 mm long sample in a 20°C thermostatic bath for 8 hours, measuring the length Lc of the sample, and then storing it in a 60°C thermostatic bath for 8 hours, measuring the length Lh of the sample. Using these values, the linear expansion coefficient (unit: / °C) was calculated using the formula: linear expansion coefficient = (Lh - Lc) / [Lc (60 - 20)].

[0036] Example 1 is an example of a polyolefin resin composition comprising 100 parts by weight of polyethylene, 10 parts by weight of recycled carbon fiber (chopped), and 1 part by weight of imine-modified polyolefin resin. The molded article of Example 1 has a Charpy impact strength (notched) of 10.1 KJ / m 2 , melt tension limit speed 12.7 m / min, appearance (smoothness) "Good", linear expansion coefficient (20 °C → 60 °C) 5.2 × 10 -5 / °C, had sufficient impact strength (sufficiently high Charpy impact strength), had good smoothness in appearance, and had a sufficiently small coefficient of linear expansion.

[0037] Example 2 is an example in which the amount of the imine-modified polyolefin resin in Example 1 was increased to 3 parts by weight, and the other components were the same as those in Example 1. The molded article of Example 2 has a Charpy impact strength (notched) of 16.9 KJ / m 2 , melt tension limit speed 17.1 m / min, appearance (smoothness) "Good", linear expansion coefficient (20 °C → 60 °C) 2.7 × 10 -5 / °C, and the impact strength was greater than that of Example 1, the smoothness of the appearance was good, and the linear expansion coefficient was smaller.

[0038] Example 3 is an example in which the amount of the imine-modified polyolefin resin in Example 1 was increased to 5 parts by weight, and the other components were the same as those in Example 1. The molded article of Example 3 has a Charpy impact strength (notched) of 16.1 KJ / m 2 , melt tension limit speed 16.8 m / min, appearance (smoothness) "Good", linear expansion coefficient (20 °C → 60 °C) 3.4 × 10 -5 / °C, and the impact strength was greater than that of Example 1, the smoothness of the appearance was good, and the linear expansion coefficient was smaller.

[0039] Example 4 is an example in which 10 parts by weight of recycled carbon fiber (milled) was blended in place of 10 parts by weight of recycled carbon fiber (chopped) in Example 2, and the other components were the same as Example 2. The molded article of Example 4 has a Charpy impact strength (notched) of 21.7 KJ / m 2 , melt tension limit speed 18.6 m / min, appearance (smoothness) "◎", linear expansion coefficient (20 °C → 60 °C) 8.5 × 10 -5 / ℃. In Example 4, recycled carbon fiber (milled) was used instead of the recycled carbon fiber (chopped) in Example 2. As a result, the impact resistance was greater than that of Example 2 and the smoothness of the appearance was improved, but the linear expansion coefficient was greater than that of Example 2.

[0040] Comparative Example 1 is an example of a polyolefin resin composition consisting of 100 parts by weight of polyethylene and 10 parts by weight of recycled carbon fiber (chopped), and does not contain imine-modified polyolefin resin, and differs from Example 1 only in that it does not contain imine-modified polyolefin resin. The molded product of Comparative Example 1 had a Charpy impact strength (notched) of 7.8 KJ / m 2 , melt tension limit speed 8.6 m / min, appearance (smoothness) "×", linear expansion coefficient (20 °C → 60 °C) 6.1 × 10 -5 / ℃. Since Comparative Example 1 did not contain imine-modified polyolefin resin, it had lower impact strength (lower Charpy impact strength value), poorer appearance smoothness, and a higher linear expansion coefficient than Example 1, which contained imine-modified polyolefin resin.

[0041] Comparative Example 2 is an example of a polyolefin resin composition consisting of 100 parts by weight of polyethylene, 10 parts by weight of recycled carbon fiber (chopped), and 3 parts by weight of acid-modified polyolefin resin, and is an example that contains 3 parts by weight of acid-modified polyolefin resin instead of the 3 parts by weight of imine-modified polyolefin resin in Example 2. The molded product of Comparative Example 2 had a Charpy impact strength (notched) of 10.3 KJ / m 2 , melt tension limit speed 11.6 m / min, appearance (smoothness) "△", linear expansion coefficient (20 °C → 60 °C) 5.6 × 10 -5 / ℃. Comparative Example 2 contained 3 parts by weight of acid-modified polyolefin resin, and therefore showed slight improvements in impact strength, smoothness of appearance, and coefficient of linear expansion compared to Comparative Example 1, which did not contain acid-modified polyolefin resin or imine-modified polyolefin resin. However, compared to Example 2, which contained 3 parts by weight of imine-modified polyolefin resin, it was inferior in all of impact strength, smoothness of appearance, and coefficient of linear expansion.

[0042] Comparative Example 3 is an example of a polyolefin resin composition consisting of 100 parts by weight of polyethylene, 10 parts by weight of recycled carbon fiber (chopped), and 5 parts by weight of acid-modified polyolefin resin, and is an example that contains 5 parts by weight of acid-modified polyolefin resin instead of 5 parts by weight of imine-modified polyolefin resin in Example 3. The molded product of Comparative Example 3 had a Charpy impact strength (notched) of 10.7 KJ / m 2 , melt tension limit speed 11.3 m / min, appearance (smoothness) "△", linear expansion coefficient (20 °C → 60 °C) 6.2 × 10 -5 / ℃. In Comparative Example 3, the amount of acid-modified polyolefin resin was increased from 3 parts by weight in Comparative Example 2 to 5 parts by weight, but there was almost no change in impact strength, smoothness of appearance, and linear expansion coefficient compared to Comparative Example 2, and compared to Example 3, which contained 5 parts by weight of imine-modified polyolefin resin, impact strength, smoothness of appearance, and linear expansion coefficient were all inferior.

[0043] As described above, the polyolefin resin composition, recycled carbon fiber reinforced resin molding, method for producing recycled carbon fiber reinforced resin pellets, and method for producing recycled carbon fiber reinforced resin molding of the present invention can produce recycled carbon fiber reinforced resin moldings of good quality.

Claims

1. A polyolefin resin composition comprising a polyolefin resin, recycled carbon fibers, and an imine-modified polyolefin resin, the imine-modified polyolefin resin accounts for 30 to 50% by weight of the recycled carbon fibers; A polyolefin resin composition, characterized in that the recycled carbon fiber is contained in an amount of 5 to 40 parts by weight per 100 parts by weight of the polyolefin resin.

2. 2. The polyolefin resin composition according to claim 1, wherein the recycled carbon fiber is a chopped recycled carbon fiber or a milled recycled carbon fiber.

3. 3. The polyolefin resin composition according to claim 1, wherein the recycled carbon fiber is a thermal decomposition product of waste carbon fiber reinforced resin.

4. A recycled carbon fiber reinforced resin molding comprising the polyolefin resin composition according to any one of claims 1 to 3.

5. A method for producing recycled carbon fiber reinforced resin pellets, comprising kneading the polyolefin resin composition according to claim 1 in a kneading extruder, and extruding the kneaded mixture from the kneading extruder to form pellets.

6. A method for producing a recycled carbon fiber reinforced resin molded body, comprising using recycled carbon fiber reinforced resin pellets obtained from the polyolefin resin composition according to any one of claims 1 to 3 and obtaining a molded body by injection molding, extrusion molding, or blow molding.

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