FIBROUS CELLULOSE, FIBROUS CELLULOSE COMPOSITE RESIN, AND METHOD FOR PREPARING FIBROUS CELLULOSE

Abstract

Fibrous cellulose highly capable of reinforcing resins, fibrous cellulose composite resins with high strength, and a method for preparing fibrous cellulose highly capable of reinforcing resins. The fibrous cellulose has an average fiber width of ≥0.1 μm, and has hydroxyl groups partially/fully substituted with carbamate groups at the substitution rate of ≥1.0 mmol/g, and has an average fiber length of >0.10 mm. This fibrous cellulose and a resin are contained in the composite resin. The method includes heat treating a cellulose raw material and urea or derivatives thereof to substitute part/all of the hydroxyl groups in the cellulose raw material with carbamate groups, and defibrating the raw material into an average fiber width of ≥0.1 μm, wherein the heat treating is performed so that the rate of carbamate-group-substitution is ≥1.0 mmol/g and an average fiber length of the material is >0.10 mm.

Claims

1. Fibrous cellulose having an average fiber width of not smaller than 0.1, and having hydroxyl groups partially or fully substituted with carbamate groups, wherein a ratio of substitution with the carbamate groups is 1.0 mmol/g or higher, and wherein the fibrous cellulose has an average fiber length of longer than 0.10 mm.

2. A fibrous cellulose composite resin, comprising: fibrous cellulose; and a resin, wherein the fibrous cellulose has an average fiber width of not smaller than 0.1 μm, and has hydroxyl groups partially or fully substituted with carbamate groups, wherein a rate of substitution with the carbamate groups is 1.0 mmol/g or higher, and wherein the fibrous cellulose has an average fiber length of longer than 0.10 mm.

3. The fibrous cellulose composite resin according to claim 2, further comprising an acid-modified resin, wherein part or all of the carbamate groups are ionically bonded with acid radicals in the acid-modified resin, and wherein the acid-modified resin has an acid value of 0.5 to 100 mgKOH/g and a MFR of 2000 g per 10 minutes or lower (190° C., 2.16 kg).

4. A method for preparing fibrous cellulose, comprising: heat treating a cellulose raw material and at least either of urea and a derivative thereof to substitute part or all of hydroxyl groups in the cellulose raw material with carbamate groups, and defibrating the cellulose raw material into an average fiber width of not smaller than 0.1 μm, wherein the heat treating is carried out so that a rate of substitution with the carbamate groups is 1.0 mmol/g or higher and an average fiber length of the cellulose raw material is longer than 0.10 mm.

5. The method for preparing fibrous cellulose according to claim 4, wherein the heat treating is carried out at pH 9 or higher.

6. The method for preparing fibrous cellulose according to claim 4, wherein the heat treating is carried out at pH 7 or lower.

Description

EXAMPLES

[0187] Next, Examples of the present invention will be discussed.

[0188] Test Examples are described which demonstrate the relationship between the pH in carbamation, rate of carbamation, and the average fiber length of the raw material pulp and the microfiber cellulose, and the physical properties of the resulting fibrous cellulose composite resin.

[0189] First, softwood kraft pulp having a moisture percentage of 10% or lower, an aqueous solution of urea having 10% solid concentration, and various pH adjusting liquids were mixed at ratios as shown in Table 1 (mass ratio in terms of solids. The amounts of the pH adjusting liquids are not indicated. As urea is weakly basic, the amounts of the pH adjusting liquids are small (about 0.02 to 0.2 g per 1 g of urea)). The resulting mixture was dried at 105° C. to obtain a dried product, which was then heat treated at 140° C. (reaction temperature) for 3 hours (duration of reaction) to obtain carbamate-modified pulp. The carbamate-modified pulp thus obtained was diluted with distilled water, stirred, and dewatered to wash, which was repeated twice. The washed carbamate-modified pulp was beaten in a Niagara beater for 4 hours to obtain carbamate-modified microfiber cellulose (fibrous cellulose). The rate of carbamation and the average fiber length of this carbamate-modified microfiber cellulose are shown in Table 1.

TABLE-US-00001 TABLE 1 Physical properties of cellulose fibers Physical properties of composite resin Conditions for raw material preparation Rate of Average fiber Average fiber Flexural Fracture pH Pulp Urea carbamation length of pulp length of MFC modulus strain — g g mmol/g mm mm — — Test 12 5 1 1.53 1.79 0.81 ○ ○ Example 1 Test 10 5 1 1.83 1.88 0.86 ○ ○ Example 2 Test  8 5 1 0.92 2.04 0.94 × ○ Example 3 Test  7 5 1 1.58 1.95 0.90 ○ ○ Example 4 Test  5 5 1 1.29 1.95 0.90 ○ ○ Example 5 Test  3 5 1 1.36 1.86 0.85 ○ ○ Example 6 Test  8 5 5 3.00 1.50 0.09 × ○ Example 7

[0190] Next, with the carbamate-modified microfiber cellulose thus obtained, an aqueous dispersion was prepared having a 2 mass % solid concentration of the carbamate-modified microfiber cellulose. Then, to 500 g of this aqueous dispersion, 5 g of maleic anhydride-modified polypropylene (MAPP) and 85 g of polypropylene powder were added, and dried by heating at 105° C. to obtain a material containing carbamate-modified microfiber cellulose. The moisture content of this material containing carbamate-modified microfiber cellulose was less than 10 mass %. The material containing carbamate-modified microfiber cellulose was kneaded in a twin-screw kneader at 200 rpm at 180° C., to thereby obtain a carbamate-modified microfiber cellulose composite resin (fibrous cellulose composite resin). This composite resin was cut in a pelleter into cylinders of 2 mm in diameter and 2 mm long, and injection molded at 180° C. into a cuboid test piece (59 mm long, 9.6 mm wide, and 3.8 mm thick). The flexural modulus and the fracture strain of the molded product are shown in Table 1.

[0191] With regard to the indications in the Table, the bending test was conducted in accordance with JIS K7171: 2008 to determine the flexural modulus. In the Table, the results are shown as “o” (circle mark) where the flexural modulus (multiple) of the composite resin was 1.3 times or more the flexural modulus of the resin per se being 1, and the results are shown as “x” (cross mark) where the flexural modulus of the composite resin was less than 1.3 times the flexural modulus of the resin per se being 1. Regarding the fracture strain test, the results are shown as “0” (circle mark) where the strain of the composite resin until fracture in the bending test was 9.0% or more, and the results are shown as “x” (cross mark) where the strain until fracture was less than 9.0%.

INDUSTRIAL APPLICABILITY

[0192] The present invention is applicable as fibrous cellulose, fibrous cellulose composite resin, and a method for preparing fibrous cellulose. For example, the fibrous cellulose composite resin may be applicable as interior materials, exterior materials, structural materials, and the like of transport equipment, such as vehicles, trains, vessels, and airplanes; casings, structural materials, internal components, and the like of electronic appliances, such as personal computers, televisions, telephones, and clocks; casings, structural materials, internal components, and the like of mobile communication equipment, such as mobile phones; housings, casings, structural materials, internal components, and the like of mobile music reproduction equipment, video reproduction equipment, printing equipment, copying equipment, sports goods, office equipment, toys, and the like; interior materials, exterior materials, structural materials, and the like of buildings, furniture, and the like; business equipment, such as stationaries and the like; and packages, containers like trays, protection members, partition members, and various others.