SURFACE MODIFIED CELLULOSE FIBER

Abstract

A process for producing surface modified bleached chemical pulp fiber comprising fluidizing the bleached chemical pulp fiber and contacting the fluidized bleached chemical pulp fiber with an aerosol of a surface modifying composition comprising a surface modifying compound

Claims

1. A process for producing surface modified bleached chemical pulp fiber comprising fluidizing a bleached chemical pulp fiber and contacting the fluidized bleached chemical pulp fiber with an aerosol of a surface modifying composition comprising a surface modifying compound.

2. The process for producing surface modified bleached chemical pulp fiber according to claim 1, wherein the aerosol comprises liquid particles of surface modifying composition.

3. The process for producing surface modified bleached chemical pulp fiber according to claim 1, wherein the bleached chemical pulp fiber is modified with an amount of 0.1-10 wt % of surface modifying compound with respect to the weight of the bleached chemical pulp fiber.

4. The process for producing surface modified bleached chemical pulp fiber according to claim 1, wherein the surface modifying composition comprises a dicarboxylic alkenoic anhydride grafted polyolefin as the surface modifying compound.

5. The process for producing surface modified bleached chemical pulp fiber according to claim 1, wherein the surface modifying composition is an aqueous dispersion of the dicarboxylic alkenoic acid anhydride grafted polyolefin.

6. The process for producing surface modified bleached chemical pulp fiber according to claim 1, wherein the surface modifying composition comprises, or consists of, a silane or a salt of said silane, according to formula I
(R.sub.1).sub.nSi(R.sub.2).sub.4-n,  (I) as the surface modifying compound, where R.sub.1 is a group capable of undergoing hydrolysis, where n is a integer chosen from 1, 2 or 3, where R.sub.2 is independently a hydrogen, methyl, ethyl or a alkyl chain having 3 to 10 carbons.

7. The process for producing surface modified bleached chemical pulp fiber according to claim 6, wherein the surface modifying composition is a solution of a silane according to formula I in an alcohol; or an aqueous solution of a salt of said silane.

8. The process for producing surface modified bleached chemical pulp fiber according to claim 6, wherein the surface modifying composition comprises of from 2 to 50 wt of the silane according to formula I.

9. The process for producing surface modified bleached chemical pulp fiber according to claim 1, wherein the bleached chemical pulp fiber is fluidized in a fluidized bed reactor.

10. The process for producing surface modified bleached chemical pulp fiber according to claim 1, wherein the bleached chemical pulp fiber is fluidized in a mixing device.

11. The process for producing surface modified bleached chemical pulp fiber according to claim 1, wherein the surface modified bleached chemical pulp fiber is dried to a water content of no more than of about 5 wt %.

12. A process for producing an agglomerate material comprising or essentially consisting of surface modified bleached chemical pulp fiber, where the surface modified bleached chemical pulp fiber is produced by fluidizing a bleached chemical pulp fiber and contacting the fluidized bleached chemical pulp fiber with an aerosol of a surface modifying composition comprising a surface modifying compound; and comprising the steps of wetting said surface modified bleached chemical pulp fiber with a binder liquid, and agglomerating the wet surface modified bleached chemical pulp fiber into an agglomerate material comprising or essentially consisting of said surface modified bleached chemical pulp fiber, where said agglomerate material has a bulk density of more than 80 g/dm.sup.3.

13. The process for producing an agglomerate material according to claim 12, where the binder liquid is water and wherein the agglomerate material comprising or essentially consisting of surface modified bleached chemical pulp fiber is dried to a water content of no more than 5 wt %.

14. The process for producing an agglomerate material according to claim 12, where the agglomerate material comprising or essentially consisting of surface modified bleached chemical pulp fiber is essentially free of non-grafted thermoplastic polyolefin.

15. An agglomerate material comprising or essentially consisting of comprising surface modified bleached chemical pulp fiber, where the surface modified bleached chemical pulp fiber is produced by fluidizing a bleached chemical pulp fiber and contacting the fluidized bleached chemical pulp fiber with an aerosol of a surface modifying composition comprising a surface modifying compound; which agglomerate material is obtained by wetting the surface modified bleached chemical pulp fiber with a binder liquid, and agglomerating the wet surface modified bleached chemical pulp fiber into an agglomerate material comprising or essentially consisting of surface modified bleached chemical pulp fiber, where said agglomerate material has has a bulk density of more than 80 g/dm.sup.3.

16. A process for producing a polymer composite material, comprising mixing a thermoplastic polymer in a melt with a surface modified bleached chemical pulp fiber, where the surface modified bleached chemical pulp fiber is produced by fluidizing a bleached chemical pulp fiber and contacting the fluidized bleached chemical pulp fiber with an aerosol of a surface modifying composition comprising a surface modifying compound; or with an agglomerate material produced by wetting the surface modified bleached chemical pulp fiber with a binder liquid, and agglomerating the wet surface modified bleached chemical pulp fiber into an agglomerate material comprising or essentially consisting of surface modified bleached chemical pulp fiber, where said agglomerate material has a bulk density of more than 80 g/dm.sup.3, wherein the thermoplastic polymer is a thermoplastic polyolefin, and the amount of thermoplastic polymer comprised in the polymer composite material is of from 30 to 99 weight percent and the amount of surface modified bleached chemical pulp fiber comprised in the polymer composite material is of from 1 to 70-weight percent, based on the total weight of the polymer composite material.

17. The process for producing surface modified bleached chemical pulp fiber according to claim 1, wherein to aerosol comprises liquid particles of surface modifying composition having an average diameter of from 1 to 450 μm.

18. The process for producing surface modified bleached chemical pulp fiber according to claim 1, wherein the surface modifying composition comprises a maleic anhydride-grafted polypropylene (MAPP) or a maleic anhydride-grafted polyethylene (MAPE) as the surface modifying compound.

19. The process for producing surface modified bleached chemical pulp fiber according to claim 1, wherein the surface modifying composition is an aqueous dispersion of a dicarboxylic alkenoic acid anhydride grafted polyolefin comprising of from 5 to 10 wt % of the dicarboxylic alkenoic acid anhydride grafted polyolefin.

20. The process for producing surface modified bleached chemical pulp fiber according to claim 1, wherein the surface modifying composition comprises, or consists of, a silane or a salt of said silane, according to formula I
(R.sub.1).sub.nSi(R.sub.2).sub.4-n,  (I) as the surface modifying compound, where R.sub.1 is C.sub.1-C.sub.10 alkoxy, —OH or a halogen, where n is a integer chosen from 1, 2 or 3, where R.sub.2 is independently a hydrogen, methyl, ethyl, or a branched alkyl or alkenyl chain having 3 to 10 carbons, or a linear alkyl or alkenyl chain having 3 to 10 carbons.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Preferred embodiments of the invention are described in the following with reference to the drawings, which are for the purpose of illustrating the present preferred embodiments of the invention and not for the purpose of limiting the same. In the drawings,

[0053] FIG. 1 shows agglomerate material essentially consisting of surface modified bleached chemical pulp fibre.

DESCRIPTION OF PREFERRED EMBODIMENTS

Surface Modification of Bleached Chemical Pulp Fiber

[0054] Surface modified bleached chemical pulp fiber was produced by fluidizing bleached chemical pulp fiber in a heated laboratory stirrer device equipped with a double stirrer blade equipped with side tip scrapers. The top lid was provided with a hole from where the aerosol of triethoxy(octyl)silane could be applied onto the fluidized bleached chemical pulp fiber. The aerosol of surface modifying composition of triethoxyoctylsilane was delivered while the stirrer device was operated at 100 rpm until an amount corresponding to approx. 2 wt %, with respect to the bleached chemical pulp fiber weight was applied. After the surface modifying composition of triethoxyoctylsilane has been delivered, the stirrer device was operated further at 200 rpm to homogenize for 15 minutes at room temperature and then reduced to 100 rpm and the temperature is increased to a temperature of approximately 95° C. The speed and temperature were maintained for another 20 minutes to cure the triethoxyoctylsilane to the fibres. After cooling back to room temperature, the surface modified bleached chemical pulp fiber was recuperated.

[0055] The surface modified bleached chemical pulp fiber were then agglomerated in a household blender. The fibres were wetted with approximately 150 parts per hundred fiber (phf) of water while operating the blender until they started to agglomerate. The agglomerate material was then collected and dried in an oven at 80° C. for several hours until dry. The agglomerate material is shown in FIG. 1.

[0056] The aggregate material of surface modified bleached chemical pulp fiber was the used in extrusion trials aimed at determining the specific energy needed to disperse the surface modified bleached chemical pulp fibers in a polyolefin matrix.

[0057] In the case of bleached chemical pulp fiber that were not surface modified and used as comparative, the agglomerate material was obtained according to the same procedure described above with the exception that the formation of agglomerates needed more water, i.e. approximately 200 parts per hundred fiber (phf) of water.

Comparative

[0058] 40 parts of bleached chemical wood pulp fiber obtained by grinding corresponding pulp sheets in a knife mill and screened over 200 μm mesh in the form of agglomerated material, 57 parts of homopolymer PP having a MFI of 47 when measured at 230° C. using a 2.16 kg load, and 3 parts MAPP coupling agent were combined into a polymer composite on a Coperion ZSK26 Mc18 co-rotating twin screw extruder equipped with screws of 25 mm in diameter and having a L/D ratio of 44.

[0059] The extruder contained 11 barrel unit sections on which the main hopper was located on section 1, a first side-feeding unit was provided at section 4, a second side-feeding unit was provided at section 7. The screws comprised several kneading sections: 3 kneading zones between section 4 and 7 and 4 kneading zones between section 7 and 11.

[0060] The minimal specific energy needed to obtain a polymer composite in which no flock could be identified via visual inspection was determined as being 0,240 kWh/kg when the bleached chemical wood pulp fiber was dosed via the first side-feeding unit at section 4 with at a screw rotation speed of 400 rpm at a total throughput was 15 kg/h. When lesser specific energy was used, by for example reducing the screw speed or feeding the fiber more downstream a suboptimal dispersion of the fibers and visible flocks within the polymer composite was observed.

Inventive

[0061] A polymer composite was obtained according to the same protocol as above, with the exception that the fiber was surface modified bleached chemical wood pulp fiber obtained according to the above described embodiment of the present invention.

[0062] The minimal specific energy needed to obtain a polymer composite in which no flock could be identified via visual inspection was determined as being 0,115 kWh/kg when the bleached chemical wood pulp fiber was dosed via the second side-feeding unit at section 7 (i.e. bypassing kneading zones between section 4 and 7) with at a screw rotation speed of 120 rpm at a total throughput was 15 kg/h.

[0063] Thus, the surface modified bleached chemical pulp fiber allows to incorporate bleached chemical pulp fiber into a polymer matrix at the same dispersion level but using about 50% less energy when compared to the bleached chemical pulp fiber that has not been surface treated.

LIST OF REFERENCE SIGNS

[0064] none