Method for producing cellulose fiber composite resin raw material and method for producing cellulose fiber composite resin molded product

Abstract

To provide a method for manufacturing a cellulose fiber composite resin raw material used for manufacturing a cellulose fiber composite resin molding, capable of efficiently manufacturing the cellulose fiber composite resin raw material in a simple process and capable of obtaining the uniformly dispersed cellulose fiber composite resin molding while preventing cellulose fibers from aggregating in resin when used as the cellulose fiber composite resin molding.SOLUTION: A method for manufacturing a cellulose fiber composite resin raw material used for manufacturing a cellulose fiber composite resin molding comprises: shear-mixing unfibrillated hydrophobic modified cellulose, 200 pts.wt. or more of solvent based on 100 pts.wt. of cellulose, and a particulate thermoplastic resin in a state that the cellulose is swelled to the solvent to fibrillate the cellulose; and compounding the cellulose with the particulate thermoplastic resin to obtain the cellulose fiber composite resin raw material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a cellulose fiber composite resin raw material, and more particularly to a method for producing a cellulose fiber composite resin raw material used for producing a cellulose fiber composite resin molded product. [Background technology]

[0002] In recent years, the United Nations has set international goals for sustainable development known as the Sustainable Development Goals (SDGs), and one of these environmental issues is the reduction of plastic usage. Efforts are being made to solve climate change by reducing the use of petroleum-derived plastics and thereby reducing GHG emissions.

[0003] For this reason, cellulose composite resins in which plant-derived cellulose is mixed with a resin raw material have been actively researched and developed. Examples include a fibrous cellulose-containing material in which fibrillated microfiber cellulose is mixed with resin powder (see Patent Document 1), and a method for producing a modified cellulose-blended resin composition in which hydrophobic cellulose is kneaded with a thermoplastic resin (see Patent Document 2).

[0004] Demand for cellulose fiber composite resins is increasing not only because cellulose is being used in resin compositions as an environmental initiative, but also because mixing cellulose fiber into resins to form composites acts as a reinforcing material for the resin, improving the strength, elasticity, and other properties of resin molded products.

[0005] However, once cellulose aggregates, it is difficult to redisperse, and if the cellulose fibers are not uniformly dispersed in the resin, this may actually result in a decrease in the strength of the molded product. However, in order to improve the dispersibility of cellulose fibers, the process has become complicated, such as by using an organic solvent or by dehydrating the dispersion of fibrillated cellulose, which can lead to problems such as a decrease in productivity and an increase in production costs (see, for example, Patent Documents 3 and 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6796111 [Patent Document 2] Patent No. 6787533 [Patent Document 3] Patent No. 5863269 [Patent Document 4] Patent No. 5030667 Summary of the Invention [Problem to be solved by the invention]

[0007] Furthermore, in recent years, research and development has progressed on the fiber diameter of the cellulose fiber to be mixed into resin, and findings have emerged that cellulose fibers with submicron to micron diameters, which are less likely to defibrate than nano-sized cellulose fibers such as nanofibers, improve the strength of resins mixed with cellulose fibers. For these reasons, there is an increasing demand for cellulose fiber composite resins in which cellulose is uniformly dispersed in the resin, preventing aggregation, and the fiber diameter of the cellulose fiber is controlled depending on the use of the resin product.

[0008] In view of the above, the inventors have repeatedly studied and improved the method for producing a cellulose fiber composite resin raw material prior to processing into a resin molded product when producing a composite resin containing cellulose fiber. As a result, they have developed a production method that allows for the production of a cellulose fiber composite resin raw material more simply and efficiently.

[0009] The present invention provides a method for producing a cellulose fiber composite resin raw material used in the production of cellulose fiber composite resin moldings, which can prevent the defibrated cellulose fibers from aggregating due to hydrogen bonding due to the presence of a particulate thermoplastic resin, and can efficiently produce a cellulose fiber composite resin raw material from which uniformly dispersed cellulose fiber composite resin moldings are produced in a simple process that does not require pre-defibration. [Means for solving the problem]

[0010] That is, the first invention is a method for producing a cellulose fiber composite resin raw material used for producing a cellulose fiber composite resin molded product, which comprises: undefibrated hydrophobically modified cellulose; Hydrophobically modified unresolved fibers The solvent is 200 parts by weight or more relative to 100 parts by weight of cellulose, and a particulate thermoplastic resin is Hydrophobically modified unresolved fibers The cellulose is shear-mixed in a state where it is swollen in the solvent. Hydrophobically modified unresolved fibers The present invention relates to a method for producing a cellulose fiber composite resin raw material, characterized in that cellulose is defibrated and then composited with the particulate thermoplastic resin to obtain a cellulose fiber composite resin raw material.

[0011] The second invention is the first invention, wherein Hydrophobically modified unresolved fibers The present invention relates to a method for producing a cellulose fiber composite resin raw material in which the average fiber diameter of the cellulose is 10 to 40 μm.

[0012] A third invention relates to a method for producing a cellulose fiber composite resin raw material according to the first or second invention, wherein the particulate thermoplastic resin has an average particle size of 100 to 500 μm.

[0013] A fourth invention relates to a method for producing a cellulose fiber composite resin raw material according to any one of the first to third inventions, wherein the raw material is shear mixed in a temperature range lower than the boiling point of the solvent.

[0014] The fifth invention relates to a method for producing a cellulose fiber composite resin molded product, in which a cellulose fiber composite resin raw material obtained by the method for producing a cellulose fiber composite resin raw material of any of the first to fourth inventions is heated, kneaded, and molded to obtain a cellulose fiber composite resin molded product. [Effects of the Invention]

[0015] According to a first aspect of the present invention, there is provided a method for producing a cellulose fiber composite resin raw material used to produce a cellulose fiber composite resin molded product, the method comprising the steps of: Hydrophobically modified unresolved fibers The solvent is 200 parts by weight or more relative to 100 parts by weight of cellulose, and a particulate thermoplastic resin is Hydrophobically modified unresolved fibers The cellulose is shear-mixed in a state where it is swollen in the solvent. Hydrophobically modified unresolved fibers Since cellulose is defibrated and then composited with the particulate thermoplastic resin to obtain a cellulose fiber composite resin raw material, the presence of the particulate thermoplastic resin prevents the defibrated cellulose fibers from agglomerating due to hydrogen bonding, and it is possible to efficiently produce a cellulose fiber composite resin raw material with uniformly dispersed cellulose fiber composite resin moldings using a simple process that does not require pre-defibration.

[0016] According to the second invention, the method for producing a cellulose fiber composite resin raw material is the same as that of the first invention, Hydrophobically modified unresolved fibers Since the average fiber diameter of cellulose is 10 to 40 μm, the use of cellulose that has not been pre-defibrated can prevent the cellulose from aggregating before being composited.

[0017] According to the method for producing a cellulose fiber composite resin raw material of the third invention, in the first or second invention, the average particle size of the particulate thermoplastic resin is 100 to 500 μm, so that cellulose is easily defibrated.

[0018] According to the method for producing a cellulose fiber composite resin raw material of the fourth invention, in any of the first to third inventions, shear mixing is carried out at a temperature range lower than the boiling point of the solvent, so the solvent does not volatilize, the cellulose fibers are maintained in a swollen state, and defibration is facilitated.When a cellulose fiber composite resin molding is produced, the cellulose fibers are easily dispersed uniformly and are less likely to aggregate.

[0019] According to the method for producing a cellulose fiber composite resin molding of the fifth invention, the cellulose fiber composite resin raw material obtained by the method for producing a cellulose fiber composite resin raw material of any of the first to fourth inventions is heated, kneaded, and molded to obtain a cellulose fiber composite resin molding, so that a cellulose fiber composite resin molding with good appearance and excellent strength properties can be obtained through a simple process. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is an enlarged photograph of a cellulose fiber composite resin raw material according to Prototype Example 4, which is produced by the production method of the present invention. [Figure 2] 1 is a photograph of a sheet-shaped cellulose fiber composite resin molding of Prototype 2 produced by the production method of the present invention. [Figure 3] 1 is a photograph of a sheet-shaped cellulose fiber composite resin molding of Comparative Example 3 produced by the production method of the present invention. [Figure 4] 1 is a photograph of a blank produced by the production method of the present invention and a multipurpose test piece A12 type cellulose fiber composite resin molding according to Prototype Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0021] The cellulose fiber composite resin raw material produced by the production method of the present invention is a raw material that is used to manufacture cellulose composite resin pellets by heating and kneading, etc., and then mixed with other resin raw materials, etc. to form a molded product, or directly processed into a molded product. Cellulose fiber is prone to agglomeration when simply mixed with resin, making it difficult to contribute to improving the strength of the resin molded product.

[0022] Therefore, by compounding the thermoplastic resin and cellulose fiber in a good condition to form a cellulose fiber composite resin raw material at the resin raw material stage before molding and processing, it is possible to prevent the cellulose fiber from agglomerating even when it is made into a resin molded product after molding and processing, and to contribute to improving the strength, elasticity, etc. of the resin molded product.

[0023] The cellulose fiber composite resin raw material of the present invention is obtained by shear mixing undefibrated hydrophobically modified cellulose, a solvent in an amount of 200 parts by weight or more per 100 parts by weight of the cellulose, and a particulate thermoplastic resin in a state in which the cellulose is swollen in the solvent. During shear mixing, the undefibrated cellulose is defibrated to form cellulose fibers, which are then composited with the particulate thermoplastic resin to form the cellulose fiber composite resin raw material.

[0024] Cellulose is hydrophobically modified cellulose in which its hydroxyl groups have been replaced with hydrophobic groups. Cellulose before hydrophobic modification has a large amount of hydroxyl groups, which makes it poorly compatible with low-polarity resins, resulting in poor dispersibility and a tendency for aggregation due to hydrogen bonds when made into cellulose fibers. Furthermore, cellulose with many hydrogen bonds is difficult to defibrate into cellulose fibers. Therefore, by substituting the hydroxyl groups of cellulose with hydrophobic groups, the hydrogen bonds when made into cellulose fibers are weakened, suppressing the occurrence of aggregation and improving dispersibility in resin. Furthermore, by making it into undefibrated hydrophobically modified cellulose, aggregation is prevented from occurring before it is composited with resin.

[0025] Hydrophobization of cellulose is carried out by any known method. For example, raw pulp is pulverized using a shredder or the like, immersed in a reaction solvent for about 30 minutes, and the temperature is raised to about 50°C while stirring. A predetermined amount of a modifying reactant and a reaction catalyst are then added, and the mixture is reacted for several hours. After washing and dehydration, hydrophobically modified cellulose in which the hydroxyl groups have been modified to hydrophobic groups is obtained. The degree of substitution (DS) of hydroxyl groups of cellulose with hydrophobic groups is preferably 0.5 or more.

[0026] Undefibrated hydrophobically modified cellulose is mixed with a particulate thermoplastic resin together with an excess amount of solvent. Examples of solvents that can be used include water and isopropanol. The reason for using an excess amount of solvent relative to the amount of cellulose is to facilitate defibration by impregnating the solvent between the cellulose fibers, which are composed of a clustered structure. Furthermore, shear mixing can cause aggregation or poor compounding with the resin, making it difficult to ensure uniform dispersion of the cellulose in the molded resin. For this reason, 200 parts by weight or more of solvent is mixed per 100 parts by weight of cellulose. While there is no upper limit on the amount of solvent, considering the efficiency of shear mixing, it is recommended to use approximately 2000 parts by weight per 100 parts by weight of cellulose. More than this amount of solvent can result in excessive viscosity and reduced solid content during shear mixing, making shear difficult. When used as a raw material for a cellulose fiber composite resin, the material can become sticky and difficult to handle.

[0027] The cellulose is then shear-mixed with the particulate thermoplastic resin while swollen in the solvent. At this time, it is preferable to use unfibrillated cellulose with an average fiber diameter of about 10 to 40 μm. The average fiber diameter of cellulose derived from natural materials is about 40 μm at most. If the average fiber diameter is less than 10 μm, the cellulose fibers may become too fine if the shear mixing time is long, which may result in aggregation and a reduced contribution to the strength and elasticity of the cellulose fiber composite resin molded product after processing and molding. The cellulose is immersed in the solvent for approximately 30 minutes to swell. Shear mixing is carried out for a time sufficient to defibrate the cellulose, although this depends on the rotation speed of the shear blade. For example, it is recommended to carry out the mixing at a rotation speed of 60 to 100 rpm for approximately 10 to 20 minutes.

[0028] It is known that cellulose fibers with larger fiber diameters contained in resin moldings contribute more to improving strength and elasticity than cellulose fibers that have been nanofiberized to the minimum unit of 3 to 4 nm in diameter. Therefore, by appropriately adjusting the shear mixing time, it is possible to arbitrarily adjust the fiber diameter of the cellulose fibers in the cellulose fiber composite resin raw material, and easily increase the contribution to the strength and elasticity of the cellulose fiber composite resin moldings.

[0029] The granular thermoplastic resin used in the present invention is not particularly limited, and examples thereof include polyolefin resins, polyamide resins, polyester resins, polyacetal resins, biodegradable resins, etc. Furthermore, natural resin materials derived from animals, plants, and microorganisms can also be used.

[0030] The cellulose, solvent, and particulate thermoplastic resin are preferably mixed and sheared while being cooled. Because shear heat occurs, it is preferable to control the temperature to a range lower than the boiling point of the solvent. This control allows the cellulose to be defibrated in a more swollen state without volatilizing the solvent, making it easier to defibrate and more efficiently combine with the resin.

[0031] As shown in the enlarged photograph of Prototype Example 4 in Figure 1, the cellulose fiber composite resin raw material is obtained in a state where cellulose fibers are coated on particulate thermoplastic resin, or where the cellulose fibers are entangled without agglomeration. Granulating the thermoplastic resin acts as a bead mill, facilitating cellulose defibration. A particle diameter of 100 to 500 μm, particularly 300 to 500 μm, results in good cellulose defibration. Particle diameters less than 100 μm are too small relative to the clearance between the blades and cylinder, making shearing difficult. On the other hand, diameters greater than 500 μm make it difficult for the resin to pass through the clearance between the blades and cylinder, potentially preventing shearing. Cellulose is particularly easily defibrated when particulate thermoplastic resins with a high elastic modulus are used. When particulate thermoplastic resins with flexibility or a low elastic modulus are used, cellulose can be defibrated by performing shear mixing for a long period of time.

[0032] The cellulose fiber composite resin raw material obtained by shear mixing is dehydrated as necessary. If the amount of solvent contained in the cellulose fiber composite resin raw material is approximately 10 parts by weight or less, it will be easier to handle during processing and molding.

[0033] The cellulose fiber composite resin raw material obtained by the manufacturing method of the present invention is melted, molded, and processed, or mixed with other resins, etc., and melted, molded, and processed to form a molded product. In this case, agglomerates of cellulose fiber contained in the molded product with a diameter of 1 mm or more are formed by agglomerating the cellulose fibers, and the agglomerates are formed within a 5 cm area of ​​a 100 μm-thick sheet-like molded product, as shown in the examples described later. 2 No agglomerates of 0.1 to 1 mm in diameter were formed per corner, and the agglomerates were measured within 5 cm of a 100 μm thick sheet. 2 This is a significant method for producing a cellulose fiber composite resin raw material, which can suppress the aggregation of cellulose fibers by reducing the number of particles per corner to less than 30. [Example]

[0034] The inventors conducted experiments to produce cellulose fiber composite resin raw materials by varying the blending amounts and types of hydrophobically modified cellulose, solvent, and granular thermoplastic resin.

[0035] [Preparation of hydrophobically modified cellulose] Hydrophobically modified cellulose was prepared using the following cellulose raw material, modifying reactant, reaction catalyst, and reaction solvent. During the preparation, the cellulose was stirred so as not to defibrate.

[0036] [Cellulose raw materials] The starting cellulose raw materials used were "CA-KP" (Canfor) (Ce1) and "Linter 512" (Buckeye Technologies) (Ce2).

[0037] [Modifying Reaction Agent] The modifying reactants used were vinyl acetate (Kishida Chemical Co., Ltd.) (R1) and vinyl laurate (Tokyo Chemical Industry Co., Ltd.) (R2).

[0038] [Reaction catalyst] The reaction catalysts used were potassium carbonate (manufactured by Kishida Chemical Co., Ltd.) (Ca1) and "DBU (registered trademark)" (manufactured by San-Apro Co., Ltd.) (Ca2).

[0039] [Reaction Solvent] Dimethyl sulfoxide (manufactured by Toray Fine Chemicals Co., Ltd.) (S1) was used as the reaction solvent.

[0040] Using the above raw materials, hydrophobically modified cellulose was prepared according to the formulation shown in Table 1.

[0041] <Hydrophobically modified cellulose 1 (HCe1)> 1200 g of cellulose raw material (Ce1) was shredded to a width of approximately 2.5 mm using a shredder. The shredded cellulose raw material was immersed in a reaction solvent (S1) for 30 minutes and heated to approximately 50 °C while stirring. 4000 g of a modification reaction agent (R1) and 800 g of a reaction catalyst (Ca1) were added and stirred for 3 to 9 hours to allow the reaction. The reaction solvent was washed with ion-exchanged water treated with ion exchange resin, and the mixture was dehydrated using a centrifuge to obtain hydrophobically modified cellulose 1. The degree of substitution (DS) of hydroxyl groups with hydrophobic groups varied depending on the stirring time after adding the modification reaction agent (R1) and the reaction catalyst (Ca1). Therefore, hydrophobically modified cellulose 1 (HCe1) was distinguished from hydrophobically modified celluloses (HCe1-1) to (HCe1-6) with different degrees of substitution, as described below. Hydrophobically modified cellulose 1-1 (HCe1-1): Stirring time 4 hours, degree of substitution (DS) 1.20 Hydrophobically modified cellulose 1-2 (HCe1-2): Stirring time 8 hours, degree of substitution (DS) 1.39 Hydrophobically modified cellulose 1-3 (HCe1-3): Stirring time 9 hours, degree of substitution (DS) 1.58 Hydrophobically modified cellulose 1-4 (HCe1-4): Stirring time 9 hours, degree of substitution (DS) 1.69 Hydrophobically modified cellulose 1-5 (HCe1-5): Stirring time 15 hours, degree of substitution (DS) 1.87 Hydrophobically modified cellulose 1-6 (HCe1-6): Stirring time 15 hours, degree of substitution (DS) 1.88

[0042] The degree of substitution (DS) was calculated by measuring the average acetylation degree. The average acetylation degree was measured in accordance with the acetylation degree measurement method in ASTM D-817-91 (Test Methods for Cellulose Acetate, etc.). 1.9 g of dried hydrophobically modified cellulose was precisely weighed, and 150 mL of a mixed solution of acetone and dimethyl sulfoxide (volume ratio 4:1) was added. 30 mL of 1N aqueous sodium hydroxide solution was then added and stirred at 25°C for 2 hours. The resulting mixture was filtered, washed with water, and dried. FT-IR analysis of the sample on the filter paper confirmed the disappearance of the absorption peak due to the carbonyl group of the ester bond, i.e., the ester bond had been hydrolyzed. Phenolphthalein was added to the filtrate as an indicator, and excess sodium hydroxide was titrated with 1N sulfuric acid (concentration factor: F). A blank test was also conducted in the same manner as above, and the average acetylation degree was measured according to the following formula, from which the degree of substitution was calculated. In the formula, A is the titer (mL) of 1N sulfuric acid for the sample, B is the titer (mL) of 1N sulfuric acid for the blank test, F is the concentration factor of 1N sulfuric acid, and W is the weight of the sample. Average acetylation rate (%) = {6.5·(BA)·F} / W Degree of substitution = (average acetylation degree 162) / (6005 - average acetylation degree 42)

[0043] <Hydrophobically modified cellulose 2 (HCe2)> 1000 g of cellulose raw material (Ce1) was shredded to a width of approximately 2.5 mm using a shredder. The shredded cellulose raw material was immersed in the reaction solvent (S1) for 30 minutes and heated to approximately 60°C while stirring. 3330 g of the modifying reaction agent (R1) and 670 g of the reaction catalyst (Ca2) were added and reacted for 6 hours. The reaction solvent was washed away with ion-exchanged water treated with ion exchange resin, and the mixture was dehydrated using a centrifuge to obtain hydrophobically modified cellulose 2 (HCe2). The degree of substitution (DS) was 0.71.

[0044] <Hydrophobically modified cellulose 3 (HCe3)> 105 g of cellulose raw material (Ce1) was shredded to a width of approximately 2.5 mm using a shredder. The shredded cellulose raw material was immersed in the reaction solvent (S1) for 30 minutes and heated to 75°C while stirring. 350 g of the modifying reaction agent (R2) and 84 g of the reaction catalyst (Ca1) were added and reacted for 4 hours. The reaction solvent was washed away with ion-exchange water treated with ion exchange resin, and the mixture was dehydrated using a centrifuge to obtain hydrophobically modified cellulose 3 (HCe3). The degree of substitution (DS) was 0.62.

[0045] <Hydrophobically modified cellulose 4 (HCe4)> 105 g of cellulose raw material (Ce2) was pulverized in a shredder to a width of approximately 2.5 mm. The pulverized cellulose raw material was immersed in reaction solvent (S1) for 30 minutes and heated to 75°C while stirring. 285 g of modifying reaction agent (R1) and 42 g of reaction catalyst (Ca1) were added and reacted for 4 hours. Ion-exchanged water treated with ion exchange resin was added to wash out the reaction solvent, and the mixture was dehydrated in a centrifuge to obtain hydrophobically modified cellulose 4 (HCe4). The degree of substitution (DS) was 1.30.

[0046] [Table 1]

[0047] [Preparation of cellulose fiber composite resin raw materials] Next, the above-mentioned hydrophobically modified celluloses 1 to 4 (HCe1 to 4) and the following raw materials were used to prepare raw materials for cellulose fiber composite resins, and prototypes 1 to 11 and comparative examples 1 to 4 were produced.

[0048] 〔solvent〕 The solvents used were ion-exchanged water (S2) and IPA (isopropanol) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (S3).

[0049] [Thermoplastic resin] The thermoplastic resins used were T1 to T3 below, and each pellet was crushed until the percentage of pellets with a diameter of 1 mm or more was 10% or less, and pellets with a diameter of 1 mm or more were removed using a sieve. The crushing equipment used was a freezing crusher for T1, and an impact crusher for T2 and T3. T1: Homopolypropylene (Novatec FL100A (registered trademark), manufactured by Japan Polypropylene Corporation, melting point 161°C, MFR 3.0g / 10min, average particle size 350μm) T2: Polyacetal ("Duracon M90-44" (registered trademark), manufactured by Polyplastics Co., Ltd., melting point 167°C, MFR 9.0 g / 10 min, average particle size 270 μm) T3: Linear low density polyethylene ("Green PE SLH218", manufactured by BRASKEM, melting point 110°C, MFR 2.3g / 10min, average particle size 340μm)

[0050] [Dispersant] Furthermore, maleic anhydride-modified polypropylene ("UMEX 1010" (registered trademark), manufactured by Sanyo Chemical Industries, Ltd.) (D1) and erucic acid amide ("DIAMID L-200" (registered trademark), manufactured by Mitsubishi Chemical Corporation) (D2) were added as dispersants as needed.

[0051] Using the above raw materials, cellulose fiber composite resin raw materials of Prototype Examples 1 to 11 and Comparative Examples 1 to 4 were prepared according to the formulations shown in Table 2.

[0052] <Prototype example 1> 9.4 parts by weight of hydrophobically modified cellulose (HCe4) (DS: 1.30), 53.1 parts by weight of solvent (S2) (567 parts by weight per 100 parts by weight of cellulose), 37.0 parts by weight of thermoplastic resin (T1), and 0.5 parts by weight of dispersant (D1) were shear mixed using a shear mixer ("TEX25αIII", manufactured by The Japan Steel Works, Ltd.) at Q / Ns = 0.005 and a cylinder temperature of 10°C to obtain the cellulose fiber composite resin raw material of Prototype Example 1.

[0053] <Prototype example 2> 6.4 parts by weight of hydrophobically modified cellulose (HCe1-2) (DS: 1.39), 36.2 parts by weight of solvent (S2) (567 parts by weight per 100 parts by weight of cellulose), 56.8 parts by weight of thermoplastic resin (T1), and 0.6 parts by weight of dispersant (D1) were shear mixed using a shear mixer ("TEX25αIII", manufactured by The Japan Steel Works, Ltd.) at Q / Ns = 0.005 and a cylinder temperature of 10°C to obtain the cellulose fiber composite resin raw material of Prototype Example 2.

[0054] <Prototype example 3> A mixture of 3.4 parts by weight of hydrophobically modified cellulose (HCe1-3) (DS: 1.58), 65.5 parts by weight of solvent (S2) (1900 parts by weight per 100 parts by weight of cellulose), 31.0 parts by weight of thermoplastic resin (T1), and no dispersant was shear mixed for 10 minutes using a shear mixer ("Simple Low-Cost Mixer (Iribus Blade) 1884", manufactured by Imoto Machinery Co., Ltd.) at a screw rotation speed of 80 rpm and a cylinder temperature of 25°C to obtain the cellulose fiber composite resin raw material of Prototype Example 3.

[0055] <Prototype example 4> 5.3 parts by weight of hydrophobically modified cellulose (HCe1-4) (DS: 1.69), 47.4 parts by weight of solvent (S2) (900 parts by weight per 100 parts by weight of cellulose), 46.8 parts by weight of thermoplastic resin (T1), and 0.5 parts by weight of dispersant (D1) were shear mixed using a shear mixer ("TEX25αIII", manufactured by The Japan Steel Works, Ltd.) at Q / Ns = 0.005 and a cylinder temperature of 10°C to obtain the cellulose fiber composite resin raw material of Prototype Example 4.

[0056] <Prototype 5> 7.1 parts by weight of hydrophobically modified cellulose (HCe1-4) (DS: 1.69), 28.6 parts by weight of solvent (S2) (400 parts by weight per 100 parts by weight of cellulose), 63.6 parts by weight of thermoplastic resin (T1), and 0.7 parts by weight of dispersant (D1) were shear mixed using a shear mixer ("TEX25αIII", manufactured by The Japan Steel Works, Ltd.) at Q / Ns = 0.005 and a cylinder temperature of 10°C to obtain the cellulose fiber composite resin raw material of Prototype Example 5.

[0057] <Prototype Example 6> 7.7 parts by weight of hydrophobically modified cellulose (HCe1-4) (DS: 1.69), 23.1 parts by weight of solvent (S2) (300 parts by weight per 100 parts by weight of cellulose), 68.5 parts by weight of thermoplastic resin (T1), and 0.8 parts by weight of dispersant (D1) were shear mixed using a shear mixer ("TEX25αIII", manufactured by The Japan Steel Works, Ltd.) at Q / Ns = 0.005 and a cylinder temperature of 10°C to obtain the cellulose fiber composite resin raw material of Prototype Example 6.

[0058] <Prototype Example 7> A cellulose fiber composite resin raw material for Prototype Example 7 was obtained by shear mixing 8.2 parts by weight of hydrophobically modified cellulose (HCe1-3) (DS: 1.58), 18.2 parts by weight of solvent (S2) (223 parts by weight per 100 parts by weight of cellulose), and 73.6 parts by weight of thermoplastic resin (T1) without adding a dispersant using a shear mixer ("TEX25αIII", manufactured by The Japan Steel Works, Ltd.) at Q / Ns = 0.005 and a cylinder temperature of 10°C.

[0059] <Prototype example 8> 11.1 parts by weight of hydrophobically modified cellulose (HCe1-6) (DS: 1.88), 63.0 parts by weight of solvent (S2) (567 parts by weight per 100 parts by weight of cellulose), 25.6 parts by weight of thermoplastic resin (T1), and 0.4 parts by weight of dispersant (D1) were shear mixed using a shear mixer ("TEX25αIII", manufactured by The Japan Steel Works, Ltd.) at Q / Ns = 0.005 and a cylinder temperature of 10°C to obtain the cellulose fiber composite resin raw material of Prototype Example 8.

[0060] <Prototype Example 9> A cellulose fiber composite resin raw material for prototype 9 was obtained by shear mixing 7.5 parts by weight of hydrophobically modified cellulose (HCe3) (DS: 0.62), 42.2 parts by weight of solvent (S2) (567 parts by weight per 100 parts by weight of cellulose), 50.3 parts by weight of thermoplastic resin (T1) without adding any dispersant using a shear mixer ("TEX25αIII", manufactured by The Japan Steel Works, Ltd.) at Q / Ns = 0.005 and a cylinder temperature of 10°C.

[0061] <Prototype example 10> A cellulose fiber composite resin raw material for prototype 10 was obtained by shear mixing 6.4 parts by weight of hydrophobically modified cellulose (HCe2) (DS: 0.71), 36.2 parts by weight of solvent (S2) (567 parts by weight per 100 parts by weight of cellulose), 57.4 parts by weight of thermoplastic resin (T2) without adding any dispersant using a shear mixer ("TEX25αIII", manufactured by The Japan Steel Works, Ltd.) at Q / Ns = 0.005 and a cylinder temperature of 10°C.

[0062] <Prototype Example 11> A cellulose fiber composite resin raw material for Prototype Example 7 was obtained by shear mixing 6.4 parts by weight of hydrophobically modified cellulose (HCe1-3) (DS: 1.58), 36.2 parts by weight of solvent (S2) (567 parts by weight per 100 parts by weight of cellulose), 57.4 parts by weight of thermoplastic resin (T3) without adding a dispersant using a shear mixer ("TEX25αIII", manufactured by The Japan Steel Works, Ltd.) at Q / Ns = 0.005 and a cylinder temperature of 10°C.

[0063] <Comparative Example 1> 3.4 parts by weight of hydrophobically modified cellulose (HCe1-1) (DS: 1.20) that had been pre-defibrated at 1500 rpm in a Supermass Colloider (Masuko Sangyo Co., Ltd.), 31.0 parts by weight of solvent (S3) (900 parts by weight per 100 parts by weight of cellulose), 65.4 parts by weight of thermoplastic resin (T1), and 0.2 parts by weight of dispersant (D2) were shear mixed for 10 minutes using a shear mixer ("Simple Low-Cost Mixer (Iribus Blade) 1884", Imoto Machinery Co., Ltd.) at a screw rotation speed of 80 rpm and a cylinder temperature of 25°C to obtain the cellulose fiber composite resin raw material of Comparative Example 1.

[0064] <Comparative Example 2> 5.2 parts by weight of hydrophobically modified cellulose (HCe1-1) (DS: 1.20) that had been pre-defibrated at 1500 rpm in a Supermass Colloider (Masuko Sangyo Co., Ltd.), 47.2 parts by weight of solvent (S3) (900 parts by weight per 100 parts by weight of cellulose), 47.2 parts by weight of thermoplastic resin (T1), and 0.3 parts by weight of dispersant (D2) were shear mixed for 10 minutes using a shear mixer ("Simple Low-Cost Mixer (Iribus Blade) 1884", Imoto Machinery Co., Ltd.) at a screw rotation speed of 80 rpm and a cylinder temperature of 25°C to obtain a cellulose fiber composite resin raw material for Comparative Example 2.

[0065] <Comparative Example 3> 3.9 parts by weight of hydrophobically modified cellulose (HCe1-5) (DS: 1.87), 22.1 parts by weight of solvent (S2) (900 parts by weight per 100 parts by weight of cellulose), and 74.0 parts by weight of thermoplastic resin (T1) were mixed in a Henschel mixer at 1000 rpm for 5 minutes without adding a dispersant. A cellulose fiber composite resin raw material for Comparative Example 3 was obtained without solid-phase shear mixing.

[0066] <Comparative Example 4> A cellulose fiber composite resin raw material for Comparative Example 4 was obtained by shear mixing 9.3 parts by weight of hydrophobically modified cellulose (HCe1-3) (DS: 1.58), 7.3 parts by weight of solvent (S2) (79 parts by weight per 100 parts by weight of cellulose), 83.4 parts by weight of thermoplastic resin (T1) without adding any dispersant using a shear mixer ("Simple Low-Cost Mixer (Iribus Blade) 1884", manufactured by Imoto Machinery Co., Ltd.) at a screw rotation speed of 80 rpm and a cylinder temperature of 25°C for 10 minutes.

[0067] [Table 2]

[0068] [Creation of cellulose fiber composite resin moldings] The cellulose fiber composite resin raw materials of each of the prototypes and comparative examples were heated and kneaded, and then press-molded into sheet-like materials to produce cellulose fiber composite resin moldings. The number of cellulose fiber agglomerates, cellulose area ratio, and bending properties of the moldings were measured and evaluated.

[0069] <Prototype example 1> The cellulose fiber composite resin raw material of Prototype Example 1 was heated and kneaded using a twin-screw kneading extruder ("TEX25αIII", manufactured by The Japan Steel Works, Ltd.) with Q / Ns = 0.01 and a cylinder temperature of 180°C to obtain a pellet-shaped kneaded product. Then, using a simple injection molding machine ("IMC-18D1", manufactured by Imoto Machinery Co., Ltd., cylinder temperature 240°C) and a mold (Multipurpose Test Model A12, manufactured by Imoto Machinery Co., Ltd., mold temperature 30-40°C), a multipurpose test piece A12 type cellulose fiber composite resin molded product of Prototype Example 1 was obtained from the pellet-shaped kneaded product.

[0070] Furthermore, using a flat plate heating press (heating temperature set to resin melting point + 20°C), a 100 µm thick sheet-like cellulose fiber composite resin raw molding was obtained as Prototype Example 1 from the pellet-like kneaded product.

[0071] <Prototype example 2> A cellulose fiber composite resin molded product of Sample 2 was obtained in the same manner as Sample 1.

[0072] <Prototype example 3> The cellulose fiber composite resin raw material of Prototype Example 3 was heated and kneaded for 5 minutes using a batch-type twin-screw mixer ("Simple Low-Cost Mixer (Iris Blade) 1884", manufactured by Imoto Machinery Co., Ltd.) with a charge amount of 5 g, a screw rotation speed of 80 rpm, and a cylinder temperature of 200°C to obtain a bulk kneaded product. Using a flat plate heating press (heating setting temperature: resin melting point + 20°C), a 100 μm-thick sheet-like cellulose fiber composite resin raw molding, Prototype Example 3, was obtained from the bulk kneaded product.

[0073] <Prototype example 4> A cellulose fiber composite resin molded product of Sample 4 was obtained in the same manner as Sample 1.

[0074] <Prototype 5> In the same manner as in Prototype 1, a cellulose fiber composite resin molded product of Prototype 5 was obtained.

[0075] <Prototype Example 6> In the same manner as in Prototype 1, a cellulose fiber composite resin molded product of Prototype 6 was obtained.

[0076] <Prototype Example 7> In the same manner as in Prototype 3, a cellulose fiber composite resin molded product of Prototype 7 was obtained.

[0077] <Prototype example 8> In the same manner as in Prototype 1, a cellulose fiber composite resin molded product of Prototype 8 was obtained.

[0078] <Prototype Example 9> In the same manner as in Prototype 1, a cellulose fiber composite resin molded product of Prototype 9 was obtained.

[0079] <Prototype example 10> In the same manner as in Prototype 1, a cellulose fiber composite resin molded product of Prototype 10 was obtained.

[0080] <Prototype Example 11> A cellulose fiber composite resin molded product of Sample 11 was obtained in the same manner as Sample 1, except that the cylinder temperature during heat kneading was set to 130°C.

[0081] <Comparative Example 1> In the same manner as in Prototype 1, a cellulose fiber composite resin molded product of Comparative Example 1 was obtained.

[0082] <Comparative Example 2> In the same manner as in Prototype Example 1, a cellulose fiber composite resin molded product of Comparative Example 2 was obtained.

[0083] <Comparative Example 3> In the same manner as in Prototype 3, a cellulose fiber composite resin molded product of Comparative Example 3 was obtained.

[0084] <Comparative Example 4> In the same manner as in Prototype Example 3, a cellulose fiber composite resin molded product of Comparative Example 4 was obtained.

[0085] The cellulose fiber composite resin molded products of each prototype and comparative example were measured for the number of agglomerates, cellulose area ratio (%), and bending properties such as bending strength (MPa) and modulus of elasticity (GPa). The results are shown in Tables 3 to 6.

[0086] [Cellulose fiber aggregates] The cellulose fiber aggregates are sheet-shaped cellulose fiber composite resin moldings 5cm 2 The number of agglomerates per corner was visually confirmed. Agglomerates with diameters of 1 mm or more and those of 0.1 to less than 1 mm were counted and defined as the number of agglomerates (pieces). Figures 2 and 3 show photographs of the sheet-like cellulose fiber composite resin moldings of Prototype Example 2 and Comparative Example 3 as representative examples.

[0087] [Cellulose area ratio] The cellulose area ratio is 5cm of a sheet of cellulose fiber composite resin molding. 2 The white areas around the corners were observed under a microscope using transmitted polarized light. The area ratio (%) of the white areas was measured. Examples for which no measurement was performed are indicated by "-" in the table.

[0088] [Bending properties] Using a plastic three-point bending jig "AGS-X" (Shimadzu Corporation), the bending strength (MPa) and modulus of elasticity (GPa) of the cellulose fiber composite resin molded product of multipurpose test piece type A12 were measured at a branch distance of 32 mm and a test speed of 1 mm / min. Examples for which measurements were not performed are marked with "-" in the table.

[0089] Regarding bending properties, blanks were prepared using only the thermoplastic resins (T1 to T3) without mixing in the hydrophobically modified cellulose or solvent. The blanks were then molded into multipurpose test specimens of type A12, and the bending strength and modulus of elasticity were measured. The magnification was also calculated from the molded specimens made of only the thermoplastic resin used in each prototype and comparative example. Figure 4 shows representative photographs of the blank and the cellulose fiber composite resin molded product of type A12 for prototype 2.

[0090] An overall evaluation was then made based on these results. Cases in which there were two or more cellulose fiber agglomerates with a diameter of 1 mm or more were marked "X". Cases in which there were fewer than two agglomerates less than 1 mm in diameter but ten or more cellulose fiber agglomerates with a diameter of 0.1 to 1.0 mm were marked "△". Of the cases in which there were fewer than two agglomerates with a diameter of 1 mm or more and fewer than ten agglomerates with a diameter of 0.1 to 1.0 mm, those in which the flexural modulus was 1.2 times or more were marked "◎", and those in which the flexural modulus was less than 1.2 or was not measured were marked "◯".

[0091] [Table 3]

[0092] [Table 4]

[0093] [Table 5]

[0094] [Table 6]

[0095] [Results and Discussion] A comparison is made between Prototypes 1 to 9 and Comparative Example 4, which all used the same particulate thermoplastic resin. In Comparative Example 4, in which the amount of solvent was small relative to the amount of hydrophobically modified cellulose added, five agglomerates with a diameter of 1 mm or more were observed. In contrast, in Prototypes 1 to 9, in which 200 parts by weight or more of cellulose was added relative to 100 parts by weight of cellulose, no agglomerates with a diameter of 1 mm or more were observed.

[0096] From this, it can be seen that shear mixing of hydrophobically modified cellulose swollen in a sufficient amount of solvent with particulate thermoplastic resin makes it difficult for agglomerates to form. This is thought to be because swelling the hydrophobically modified cellulose with a solvent allows the solvent to penetrate between the fibers, making it easier to defibrate, and because pre-hydrophobically modifying the cellulose weakens the hydrogen bonds between the fibers. It is thought that there is no difference in the likelihood of agglomerates forming if the amount of solvent added is 200 parts by weight or more per 100 parts by weight of cellulose.

[0097] Since the particulate thermoplastic resin is thought to act as a bead mill, it is thought that by shear mixing with the hydrophobically modified cellulose, an appropriate amount of shear was applied to the cellulose, which promoted defibration.

[0098] It can also be inferred that the presence of the particulate thermoplastic resin between the defibrated cellulose during shear mixing prevented the reagglomeration of the defibrated cellulose fibers that occurs when cellulose is pre-defibrated alone.

[0099] Furthermore, in Prototype Example 8, in which the amount of particulate thermoplastic resin was small relative to the hydrophobically modified cellulose, a small amount of agglomerates with a diameter of 0.1 to 1.0 mm was confirmed. Because the amount of particulate thermoplastic resin, which is thought to act as a bead mill, was small relative to the hydrophobically modified cellulose, defibration was thought to be more difficult than when there was a large amount of particulate thermoplastic resin.

[0100] No agglomerates with a diameter of 1 mm or more were observed in Prototypes 10 and 11, which used different particulate thermoplastic resins. Note that the particulate thermoplastic resin T3 used in Prototype 11 has a lower elastic modulus than the particulate thermoplastic resin T1 used in Prototypes 1 to 9, and it is thought that this resulted in more agglomerates with a diameter of 0.1 to 1.0 mm than in the other prototypes, and that the cellulose area ratio was also higher. In other words, it is thought that using a particulate thermoplastic resin with a high elastic modulus is more effective in defibrating cellulose.

[0101] It was confirmed that the cellulose raw material used for the hydrophobically modified cellulose is not particularly limited, and good results were obtained even if different cellulose raw materials were used. Furthermore, it is understood that the degree of substitution of the hydrophobically modified cellulose is not particularly limited, as long as the hydrophobic modification is carried out to the extent that the hydrogen bonds between cellulose fibers are weakened.

[0102] In Comparative Examples 1 and 2, in which the cellulose was pre-defibrated, a large number of agglomerates with diameters of 0.1 to 1.0 mm were observed. This is thought to be due to the pre-defibration and further mixing in the cellulose fiber state, which resulted in re-aggregation.

[0103] In addition, in Comparative Example 3, which was only mixed with a mixer, many agglomerates with a diameter of 1 mm or more and many agglomerates with a diameter of 0.1 to 1.0 mm were confirmed, confirming that cellulose was adequately defibrated by shear mixing. [Industrial Applicability]

[0104] According to the method for producing a cellulose fiber composite resin raw material of the present invention, a cellulose fiber composite resin raw material can be produced efficiently through a simple process, from which a cellulose fiber composite resin molded product with few agglomerates and uniformly dispersed cellulose fibers can be obtained. This makes it possible to reduce the amount of petroleum-derived plastics used, contribute to solving environmental problems, and easily produce a resin molded product with excellent strength properties.

Claims

1. A method for producing a cellulose fiber composite resin raw material used in the production of a cellulose fiber composite resin molded product, comprising: Undefibrated hydrophobically modified cellulose, 200 parts by weight or more of a solvent per 100 parts by weight of the undefibrated hydrophobically modified cellulose, and a particulate thermoplastic resin are shear-mixed in a state in which the undefibrated hydrophobically modified cellulose is swollen in the solvent, whereby the undefibrated hydrophobically modified cellulose is defibrated and composited with the particulate thermoplastic resin to obtain a cellulose fiber composite resin raw material. A method for producing a cellulose fiber composite resin raw material, comprising:

2. 2. The method for producing a cellulose fiber composite resin raw material according to claim 1, wherein the undefibrated hydrophobically modified cellulose has an average fiber diameter of 10 to 40 μm.

3. The method for producing a cellulose fiber composite resin raw material according to claim 1 or 2, wherein the average particle diameter of the particulate thermoplastic resin is 100 to 500 μm.

4. The method for producing a cellulose fiber composite resin raw material according to any one of claims 1 to 3, wherein the shear mixing is carried out in a temperature range lower than the boiling point of the solvent.

5. A method for producing a cellulose fiber composite resin molded product, in which a cellulose fiber composite resin raw material obtained by the method for producing a cellulose fiber composite resin raw material according to any one of claims 1 to 4 is heated, kneaded, and molded to produce a cellulose fiber composite resin molded product.

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