Fiber-reinforced resin composition and molding of the same

Abstract

To provide a resin composition which is usable in a molding mounted on a body, is lightweight, and has high strength and impact resistance, and a molding of the same.SOLUTION: There are provided a fiber-reinforced resin composition which contains a hydrophobized cellulose nanofiber in a polymethylpentene resin, and a molding of the same.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a fiber-reinforced resin composition and a molded article thereof. [Background technology]

[0002] Polybutylene succinate and polypropylene are used as materials for the frame parts of VR goggles and other molded objects worn on the body. However, polybutylene succinate not only has low strength, but also has a high specific gravity, making it heavy and difficult to wear for long periods of time. Meanwhile, polypropylene, while having a low specific gravity, is said to have drawbacks such as insufficient strength and impact resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 02-175247 [Patent Document 2] Japanese Patent Application Publication No. 09-290864 Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, an object of the present invention is to provide a resin composition that is lightweight and has high strength and impact resistance and can be used for molded articles to be worn on the body, and to provide a molded article made from the resin composition. [Means for solving the problem]

[0005] Polymethylpentene is a polyolefin resin obtained by polymerizing methylpentene, which is obtained by reacting propylene with an alkali metal catalyst. Polymethylpentene is transparent, has excellent heat resistance, and is the lightest and has the lowest specific gravity of any thermoplastic resin, so it is used in food wraps, gas separation membranes, food containers, etc. (Patent Documents 1 and 2, etc.). However, the strength of polymethylpentene is equivalent to that of polypropylene, and molded articles worn on the body are not anticipated as an application field for polymethylpentene. Therefore, the inventors conducted various studies to increase the strength of polymethylpentene, and as a result, they found that by kneading hydrophobic cellulose nanofibers into polymethylpentene resin, a fiber-reinforced resin composition was obtained that had strength, particularly impact resistance, properties that exceeded those of polypropylene, despite having an extremely low specific gravity, and that goggles and other body accessories made using molded articles of this resin composition were comfortable to wear even for long periods of time and also had high strength and impact resistance, thereby completing the present invention.

[0006] That is, the present invention provides the following [1] to [9]. [1] A fiber-reinforced resin composition containing hydrophobized cellulose nanofibers in a polymethylpentene resin. [2] The fiber-reinforced resin composition according to [1], containing 1 part by mass or more and 50 parts by mass or less of hydrophobic cellulose nanofibers per 100 parts by mass of polymethylpentene resin. [3] The fiber-reinforced resin composition according to [1] or [2], which is an injection-molded or extrusion-molded resin composition. [4] The fiber-reinforced resin composition according to any one of [1] to [3], wherein the hydrophobized cellulose nanofiber is a cellulose nanofiber in which the hydroxyl groups of the sugar chains constituting the cellulose nanofiber have been modified with alkanoyl groups or alkenoyl groups. [5] A method for producing the fiber-cured resin composition according to any one of [1] to [4], characterized by kneading hydrophobized cellulose nanofibers or hydrophobized pulp with polymethylpentene resin. [6] A molded article made of the fiber-reinforced resin composition according to any one of [1] to [4]. [7] The molded article according to [6], which is an accessory worn on the body. [8] The molded article according to [7], wherein the accessory is selected from goggles, helmets, headphones, hearing aids, and sports protective gear. [9] The molded article according to [8], wherein the goggles are selected from eyeglasses, sports goggles, VR goggles, AR goggles, MR goggles, and goggles for night vision scopes. [Effects of the Invention]

[0007] The fiber-reinforced resin composition of the present invention has a very low specific gravity, yet has strength, particularly impact resistance, exceeding that of polypropylene. Furthermore, accessories such as goggles that are worn on the body and are made using a molded article of this fiber-reinforced resin composition are comfortable to wear for long periods of time and have high strength and impact resistance. DETAILED DESCRIPTION OF THE INVENTION

[0008] Terms used in this specification are used in the sense commonly used in the art unless otherwise specified.

[0009] In this specification, cellulose is a compound having the molecular formula (CH 10 O5) n It is a carbohydrate (polysaccharide) represented by the formula: It is the main component of plant cell walls and plant fibers, accounts for one-third of natural plant matter, and is the most abundant carbohydrate on Earth. In the present invention, cellulose includes cellulose and lignocellulose. Cellulose nanofibers refer to nanofibers made of cellulose (cellulose nanofibers) and / or nanofibers made of lignocellulose (lignocellulose nanofibers). Here, nanofibers are fibrous materials with a diameter of 1 nm to 100 nm and a length 100 times or more the diameter.

[0010] One aspect of the present invention is a fiber-reinforced resin composition containing hydrophobized cellulose nanofibers in a polymethylpentene resin. The polymethylpentene resin used in the present invention is a type of polyolefin resin obtained by polymerizing methylpentene, which is obtained by reacting propylene with an alkali metal catalyst as described above. Polymethylpentene is transparent, has excellent heat resistance, and has the lowest specific gravity and lightest weight of all thermoplastic resins, so it is used in food wraps, gas separation membranes, food containers, etc. However, molded articles worn on the body are not at all anticipated as a field of application for polymethylpentene resin. Polymethylpentene is commercially available in various grades under the trade name TPX (registered trademark) from Mitsui Chemicals, Inc.

[0011] The cellulose nanofibers used in the present invention are preferably hydrophobized cellulose nanofibers, which facilitate dispersion in polymethylpentene resins.Preferably, the hydrophobized cellulose nanofibers are cellulose nanofibers in which the hydroxyl groups of the sugar chains constituting the cellulose nanofibers have been modified with alkanoyl or alkenoyl groups. Here, the alkanoyl or alkenoyl group with which the hydroxyl group of the sugar chain is modified is preferably a straight or branched chain alkanoyl or alkenoyl group having 2 to 24 carbon atoms, more preferably a straight or branched chain alkanoyl or alkenoyl group having 2 to 18 carbon atoms, and even more preferably a straight or branched chain alkanoyl group having 2 to 18 carbon atoms, and specific examples include an acetyl group, a propionyl group, and a butyryl group.

[0012] Such hydrophobic cellulose nanofibers can be produced, for example, by the method described in JP 2016-176052 A. Hydrophobic pulp can also be produced, for example, by the method described in JP 2016-176052 A. Specifically, for example, acetylated pulp can be produced by reacting pulp with acetic anhydride in the presence of potassium carbonate.

[0013] The content ratio of polymethylpentene resin to hydrophobic cellulose nanofiber in the fiber-reinforced resin composition of the present invention is not particularly limited. However, from the viewpoint of maintaining a low specific gravity of the resulting molded body and improving strength and impact resistance, it is preferable to contain 1 part by mass or more and 50 parts by mass or less of hydrophobic cellulose nanofiber per 100 parts by mass of polymethylpentene resin, more preferably 1 part by mass or more and 40 parts by mass or less of hydrophobic cellulose nanofiber per 100 parts by mass of polymethylpentene resin, even more preferably 1 part by mass or more and 30 parts by mass or less of hydrophobic cellulose nanofiber per 100 parts by mass of polymethylpentene resin, and even more preferably 1 part by mass or more and 20 parts by mass or less of hydrophobic cellulose nanofiber per 100 parts by mass of polymethylpentene resin.

[0014] In addition to the two components, the fiber-reinforced resin composition of the present invention may contain additives such as compatibilizers; surfactants; polysaccharides such as starches and alginic acid; natural proteins such as gelatin, glue and casein; inorganic compounds such as tannin, zeolite, ceramics and metal powder; colorants; plasticizers; fragrances; pigments; flow adjusters; leveling agents; conductive agents; antistatic agents; UV absorbers; UV dispersants; and deodorizers.

[0015] The fiber-reinforced resin composition of the present invention can basically be produced by kneading hydrophobicized cellulose nanofibers with polymethylpentene resin. Here, by kneading hydrophobicized pulp (the raw material for hydrophobicized cellulose nanofibers) with polyterpene resin using a kneader or the like, the shear stress during kneading promotes fibrillation of the hydrophobicized pulp, allowing the production of a uniform mixed composition of hydrophobicized cellulose nanofibers and polymethylpentene resin. Therefore, another aspect of the present invention is a method for producing a fiber-reinforced resin composition containing hydrophobized cellulose nanofibers in polymethylpentene resin, which method comprises kneading hydrophobized cellulose nanofibers or hydrophobized pulp with polymethylpentene resin.

[0016] In the production method of the present invention, the amounts of the hydrophobized cellulose nanofiber or hydrophobized pulp and the polymethylpentene resin used are the same as those described above.

[0017] When mixing hydrophobized cellulose nanofibers or hydrophobized pulp with polymethylpentene resin, both components may be mixed at room temperature and then heated, or they may be mixed while being heated. When heating, the mixing temperature is preferably a temperature at which the polymethylpentene resin can be processed. The heating temperature is preferably a temperature above the melting point of polymethylpentene, 220 to 240°C, for example, 220 to 260°C. By setting the mixing temperature within this temperature range, the hydrophobized cellulose nanofibers and polymethylpentene resin can be mixed uniformly.

[0018] As a mixing method, a method of kneading with a kneading machine such as a bench roll, a Banbury mixer, a kneader or a planetary mixer, a method of mixing with a stirring blade, a method of mixing with a revolution / rotation type stirrer, etc. are preferred.

[0019] The resulting fiber-reinforced resin composition of the present invention contains a uniform mixture of hydrophobic cellulose nanofibers and polymethylpentene resin. The resulting resin composition can be molded into any shape using various molding methods. Therefore, another aspect of the present invention is a molded article made of a fiber-reinforced resin composition containing hydrophobized cellulose nanofibers in a polymethylpentene resin.

[0020] The molding method may be mold molding, injection molding, extrusion molding, blow molding or foam molding, with injection molding and extrusion molding being preferred.

[0021] The molded article of the present invention is lightweight because it has a specific gravity of 1.10 or less. In addition, its bending strength and impact resistance are improved compared to the polymethylpentene resin from which it is made, making it particularly useful as a body accessory. The specific gravity of the molded product of the present invention is 0.80 g / cm 3More than 1.10g / cm 3 Preferably less than 0.83 g / cm 3 More than 1.00g / cm 3 Less than 0.85 g / cm is more preferable. 3 More than 0.99g / cm 3 The following is even more preferred: The bending strength is preferably 30 MPa to 80 MPa, more preferably 40 MPa to 80 MPa, and even more preferably 50 MPa to 80 MPa. The bending modulus is preferably 1000 MPa to 3500 MPa, more preferably 1500 MPa to 3500 MPa, and even more preferably 2000 MPa to 3500 MPa. The impact resistance is 4 KJ / m 2 More than 10KJ / m 2 Preferably less than 5KJ / m 2 More than 10KJ / m 2 Less than 6KJ / m is more preferable. 2 More than 10KJ / m 2 The following is even more preferred: Here, flexural strength can be measured according to ASTM D790 Flexural Test Method for Plastics, flexural modulus can be measured according to ASTM D790 Flexural Test Method for Plastics, and impact resistance is Charpy impact strength (unnotched) which can be measured according to ASTM D256 Notched Izod Impact Test for Plastics.

[0022] Examples of accessories worn on the body include goggles, helmets, headphones, hearing aids, sports protective gear, etc. Examples of the goggles include glasses, sports goggles, VR goggles, AR goggles, MR goggles, and goggles for night vision scopes. The molded article of the present invention is particularly useful as a frame for these various goggles. [Example]

[0023] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0024] Example 1 Acetylated pulp obtained by the method described in JP 2016-176052 A and polymethylpentene were charged into a twin-screw extruder and melt-kneaded at 220° C. 1 part by mass, 5 parts by mass, 10 parts by mass, 15 parts by mass, or 20 parts by mass of acetylated pulp was used per 100 parts by mass of polymethylpentene. The specific gravity of the polymethylpentene used is 0.8, the bending strength is 36 MPa, the bending modulus is 1450 MPa, and the impact resistance is 10 KJ / m 2 It was. The specific gravity of the obtained hydrophobic cellulose nanofiber-containing polymethylpentene resin is 0.85-1.10, the bending strength is 50-80 MPa, the bending modulus is 1000-3500 MPa, and the impact resistance is 5-10 KJ / m 2 It was. The hydrophobized cellulose nanofiber-containing polymethylpentene resin of the present invention is lightweight, has high strength and impact resistance, and has been found to be useful as a material for accessories such as goggles, helmets, headphones, hearing aids, and sports protective gear.

Claims

1. A fiber-reinforced resin composition containing hydrophobized cellulose nanofibers in a polymethylpentene resin.

2. The fiber-reinforced resin composition according to claim 1, containing 1 part by mass or more and 50 parts by mass or less of hydrophobic cellulose nanofibers per 100 parts by mass of polymethylpentene resin.

3. 2. The fiber-reinforced resin composition according to claim 1, which is an injection-moldable resin composition.

4. 2. The fiber-reinforced resin composition according to claim 1, wherein the hydrophobized cellulose nanofibers are cellulose nanofibers in which the hydroxyl groups of the sugar chains constituting the cellulose nanofibers have been modified with alkanoyl groups or alkenoyl groups.

5. A method for producing the fiber-cured resin composition according to any one of claims 1 to 4, characterized by kneading hydrophobized cellulose nanofibers or hydrophobized pulp with polymethylpentene resin.

6. A molded article made of the fiber-reinforced resin composition according to any one of claims 1 to 4.

7. 7. The molded article according to claim 6, wherein the molded article is an accessory worn on the body.

8. 8. The molded article according to claim 7, wherein the accessory is selected from the group consisting of goggles, helmets, headphones, hearing aids, and sports protective gear.

9. 9. The molded article according to claim 8, wherein the goggles are selected from the group consisting of eyeglasses, sports goggles, VR goggles, AR goggles, MR goggles, and goggles for night vision scopes.