Modified cellulose fibers and cellulose composite thereof

Patent metadata

Field	Value
Publication number	US-8992731-B2
Application number	US-201113323063-A
Country	US
Kind code	B2
Filing date	Dec 12, 2011
Priority date	Jun 12, 2009
Publication date	Mar 31, 2015
Grant date	Mar 31, 2015

Abstract

An object of the invention is to provide cellulose fibers which can give a cellulose composite that renders high transparency, a reduction in linear expansion coefficient, and a high modulus of elasticity possible. The invention relates to: a process for producing modified cellulose fibers which includes a modification reaction step of reacting cellulose with an aromatic compound in an organic acid to thereby modify the cellulose with an aromatic-ring-containing substituent; cellulose fibers modified with aromatic-ring-containing substituent; a dispersion of the cellulose fibers; and a cellulose fiber composite obtained from the same.

First claim

The invention claimed is:

1. A sheet of modified cellulose fibers which comprises cellulose fibers having an average fiber diameter of 100 nm or less and having a cellulose I type crystal structure in which 10% to 60% by mole of all hydroxyl groups of the cellulose have been modified with an aromatic-ring-containing substituent,
wherein the sheet of modified cellulose fibers have a haze value measured with illuminant C of 3 or less
wherein said haze value is measured after making a composite material by: immersing the cellulose fiber sheet having a thickness regulated so that the sheet has a basis weight of 40 g/m 2 , in a solution prepared by mixing 96 parts by weight of bis(methacryloyloxymethyl)tricyclo[5.2.1.0 2,6 ]decane with 6 parts by weight of pentaerythritol tetrakis(β-thiopropionate), 0.05 parts by weight of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and 0.05 parts by weight of benzophenone; holding the sheet under vacuum overnight; subsequently sandwiching the sheet between two glass plates; performing a curing using an electrodeless mercury lamp; thereafter separating the sheet from the glass plates; and then heating the sheet in a 190° C. vacuum oven for 4 hours,
wherein the aromatic ring of each aromatic-ring-containing substituent is bonded to the cellulose by a connecting group selected from the group consisting of an ester group, an ether group and a carbamate group;
the aromatic-ring-containing substituent is a substituent derived from an aromatic hydrocarbon compound, a heterocyclic aromatic compound, or a non-benzenoid aromatic compound;
the aromatic-ring-containing substituent each may be configured of two or more moieties of any of the aromatic hydrocarbon compound, the heterocyclic aromatic compound, and the non-benzenoid aromatic compound, the moieties having been connected to each other with a single bond or an alkyl group having 1-3 carbon atoms; and
the aromatic-ring-containing substituent may be one in which hydrogen atom thereof has been replaced with an alkyl group having 1-12 carbon atoms.

2. The sheet of modified cellulose fibers according to claim 1 , wherein the cellulose fibers give a wide-angle X-ray diffraction image in which the ratio of the “average diffraction intensity in the scanning angle range of 18-19 degrees” to the “intensity of a diffraction peak derived from cellulose I type crystals in the scanning angle range of 20-24 degrees”, is 0.8 or less,
wherein the aromatic ring of each aromatic-ring-containing substituent is bonded to the cellulose by one connecting group selected from the group consisting of an ester group, an ether group and a carbamate group such that the aromatic-ring-containing substituent has a structure selected from the group consisting of one of the following formulae (1) to (3):

wherein Ar is selected from the group consisting of an aromatic hydrocarbon compound, a heterocyclic aromatic compound, and a non-benzenoid aromatic compound; and
wherein Ar is unsubstituted or a hydrogen atom of said Ar is replaced with an alkyl group having 1-12 carbon atoms.

3. The sheet of modified cellulose fibers according to claim 1 , wherein the modified cellulose fibers have an average fiber diameter of 80 nm or less.

4. The sheet of modified cellulose fibers according to claim 1 , wherein the modified cellulose fibers have an average fiber diameter of 4 nm to 100 nm.

5. A cellulose fiber composite which comprises a matrix and the sheet of modified cellulose fibers according to claim 1 .

6. The sheet of modified cellulose fibers according to claim 1 , wherein 11% to 60% by mole of all hydroxyl groups of the cellulose have been modified with an aromatic-ring-containing substituent.

7. The sheet of modified cellulose fibers according to claim 1 , wherein 15% to 60% by mole of all hydroxyl groups of the cellulose have been modified with an aromatic-ring-containing substituent.

8. The sheet of modified cellulose fibers according to claim 1 , wherein 10% to 55% by mole of all hydroxyl groups of the cellulose have been modified with an aromatic-ring-containing substituent.

9. The sheet of modified cellulose fibers according to claim 1 , wherein 10% to 50% by mole of all hydroxyl groups of the cellulose have been modified with an aromatic-ring-containing substituent.

10. The sheet of modified cellulose fibers according to claim 1 , wherein 10% to 45% by mole of all hydroxyl groups of the cellulose have been modified with an aromatic-ring-containing substituent.

11. The sheet of modified cellulose fibers according to claim 1 , wherein 10% to 40% by mole of all hydroxyl groups of the cellulose have been modified with an aromatic-ring-containing substituent.

12. The sheet of modified cellulose fibers according to claim 1 , wherein the haze value measured with illuminant C is 2 or less.

13. The sheet of modified cellulose fibers according to claim 1 , wherein the haze value measured with illuminant C is 1 or less.

14. The sheet of modified cellulose fibers according to claim 1 , wherein the thickness of the sheet ranges from 1 μm to 1,000 μm.

15. The sheet of modified cellulose fibers according to claim 14 , wherein the thickness of the sheet is at least 5 μm.

16. The sheet of modified cellulose fibers according to claim 14 , wherein the thickness of the sheet is at most 250 μm.

Assignees

• Akai Hideko
• Mitsubishi Chem Corp

Inventors

• Akai Hideko

Classifications

• D06M13/1845

  Aromatic mono- or polycarboxylic acids · CPC title

• D06M13/395

  Isocyanates · CPC title

• C08J2351/02

  grafted on to polysaccharides · CPC title

• C08B11/16

  Aryl or aralkyl ethers · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title