Super microfibrillated cellulose, process for producing the same, and coated paper and tinted paper using the same

• US 6,214,163 B1
• Filed: 08/21/2000
• Issued: 04/10/2001
• Est. Priority Date: 04/07/1995
• Status: Expired due to Term

• Current Assignee: Tokushu Paper Mfg. Co., Ltd. (Tokushu Tokai Paper Company Limited)
• Original Assignee: Tokushu Paper Mfg. Co., Ltd. (Tokushu Tokai Paper Company Limited)
• Inventors: Ueno, Katsuhiko, Matsuda, Yuji, Hirose, Mariko
• Primary Examiner(s): Chin, Peter
• Application Number:
  US09/641,955
• Time in Patent Office: 232 Days
• Field of Search: 162/9, 162/100, 162/176, 162/187, 162/162, 162/28, 162/135, 162/129, 162/130, 427/391, 427/395
• US Class Current: 162/9
• CPC Class Codes: D21C 9/007 by mechanical or physical means
• CPC Class Codes: D21D 1/36 with vertical shaft
• CPC Class Codes: D21H 11/18 Highly hydrated, swollen or fibrillatable fibres
• CPC Class Codes: D21H 21/28 Colorants ; Pigments or opacifying agents
• CPC Class Codes: D21H 27/38 at least one of the sheets having a fibrous composition differing from that of other sheets

Abstract

A super microfibrillated cellulose having an arithmetic average fiber length of 0.05 to 0.1 mm, a water retention value of at least 350%, a rate of the number of fibers not longer than 0.25 mm of at least 95% based on the total number of the fibers as calculated by adding up, and an axial ratio of the fibers of at least 50. The super microfibrillated cellulose is produced by passing a slurry of a previously beaten pulp through a rubbing apparatus having two or more grinders which are arranged so that they can be rub together to microfibrillate the pulp to obtain microfibrillated cellulose and further super microfibrillate the obtained microfibrillated cellulose with a high-pressure homogenizer to obtain the super microfibrillated cellulose. A coated paper produced with a coating material containing the super microfibrillated cellulose, and a tinted paper produced from a paper stock containing the super microfibrillated cellulose as a carrier carrying a dye or pigment are also provided.

Claims

1. A process for producing a super microfibrillated cellulose, comprising passing a slurry of a previously beaten pulp through a rubbing part of a rubbing apparatus having two or more grinders each composed of abrasive grains having a grain size of No. 16 to 120 to microfibrillate the pulp and thereby to obtain microfibrillated cellulose, and further super microfibrillating the obtained microfibrillated cellulose with a high-pressure homogenizer to obtain super microfibrillated cellulose having an arithmetic average fiber length of 0.05 to 0.1 mm, a water retention value of at least 350%, a rate of the number of fibers not longer than 0.25 mm of at least 95% based on the total number of the fibers as calculated by adding up, and an axial ratio of the fibers of at least 50.

2. A process for producing a super microfibrillated cellulose according to claim 1, wherein said slurry of previously beaten pulp is obtained by beating long fiber pulp having an arithmetic average fiber length of at least 0.8 mm to a freeness of not higher than 400 ml CSF.

3. A process for producing a super microfibrillated cellulose according to claim 1, wherein said slurry of previously beaten pulp is obtained by beating short fiber pulp having an arithmetic average fiber length of shorter than 0.8 mm to a freeness of not higher than 600 ml CSF.

4. A process for producing a super microfibrillated cellulose according to claim 1, wherein the solid concentration of said pulp slurry to be passed through said rubbing part of said rubbing apparatus is 6% by weight or below.

5. A process for producing a super microfibrillated cellulose according to claim 1, wherein said rubbing apparatus is provided with an upper fixed grinder and a lower rotating grinder which are arranged so that they can rub together.

6. A process for producing a coated paper, comprising coating at least one surface of a base paper with a coating material containing a super microfibrillated cellulose having an arithmetic average fiber length of 0.05 to 0.1 mm, a water retention value of at least 350%, the number of fibers not longer than 0.25 mm being at least 95% based on the total number of the fibers, and an axial ratio of the fibers of at least 50.

7. A coated paper comprising a base paper and a coating layer formed on at least one surface of the base paper, said coating layer containing a super microfibrillation cellulose having an arithmetic average fiber length of 0.05 to 0.1 mm, a water retention value of at least 350%, the number of fibers not longer than 0.25 mm being at least 95% based on the total number of the fibers, and an axial ratio of the fibers of at least 50.

8. A process for producing a tinted paper, comprising supporting a dye or pigment on a super microfibrillated cellulose having an arithmetic average fiber length of 0.05 to 0.1 mm, a water retention value of at least 350%, the number of fibers not longer than 0.25 mm being at least 95% based on the total number of the fibers, and an axial ratio of the fibers of at least 50 to form a carrier carrying the dye or pigment, adding the carrier carrying the dye or pigment to a paper stock prepared mainly from a papermaking pulp, and manufacturing paper from the resultant mixture.

9. A process for producing a tinted paper according to claim 8, wherein said carrier carrying the dye or pigment is prepared by adding an aqueous solution or aqueous suspension of the dye or pigment to an aqueous suspension of a super microfibrillated cellulose having an arithmetic average fiber length of 0.05 to 0.1 mm, a water retention value of at least 350%. the number of fibers not longer than 0.25 mm being at least 95% based on the total number of the fibers, and an axial ratio of the fibers of at least 50, and homogeneously stirring the resultant mixture.

10. A tinted paper comprising a paper manufactured mainly from a papermaking pulp, and a carrier carrying a dye or pigment uniformly dispersed in the paper, said carrier carrying the dye or pigment being prepared by supporting the dye or pigment on a super microfibrillated cellulose having an arithmetic average fiber length of 0.05 to 0.1 mm, a water retention value of at least 350%, the number of fibers not longer than 0.25 mm being at least 95% based on the total number of the fibers, and an axial ratio of the fibers of at least 50.