Process for producing synthetic pulp from a film of a mixture of polypropylene and low density polyethylene

• US 3,950,473 A
• Filed: 05/21/1973
• Issued: 04/13/1976
• Est. Priority Date: 12/20/1971
• Status: Expired due to Term

• Current Assignee: Chisso Corporation
• Original Assignee: Chisso Corporation
• Inventors: Kurita, Mitsuo, Uno, Mitsumasa, Iwahori, Eitaro
• Primary Examiner(s): Arnold, Donald J.
• Assistant Examiner(s): Lowe, James B.
• Application Number:
  US05/362,580
• Time in Patent Office: 1,058 Days
• Field of Search: 264/DIG. 47, 264/141, 264/151, 264/349, 264/210 R, 28/DIG. 1, 162/157 R
• US Class Current: 264/141
• CPC Class Codes: B02C 13/12 with vortex chamber
• CPC Class Codes: B02C 18/148 specially adapted for disintegrating plastics, e.g. cinematographic films for plastic bottles B02C19/0093, disintegrating plastics B29B17/00
• CPC Class Codes: D01G 11/00 Disintegrating fibre-containing articles to obtain fibres for re-use
• CPC Class Codes: D21B 1/12 by wet methods, by the use of steam beaters D21D1/00
• CPC Class Codes: D21H 13/14 Polyalkenes, e.g. polystyrene polyethylene
• CPC Class Codes: D21H 5/202 polyolefins
• CPC Class Codes: Y02W 30/66 Disintegrating fibre-containing textile articles to obtain fibres for re-use
• CPC Class Codes: Y10S 264/47 Processes of splitting film, webs or sheets

Abstract

Synthetic pulp having a peculiar structure is prepared by making a composition consisting of 50 to 90 parts by weight of polypropylene having a melt flow rate of 30 to 150 and 50 to 10 parts by weight of low density polyethylene having a melt index of 0.5 to 10 into a film having a thickness of 70 μ or less, uniaxially stretching the film, cutting the stretched film to a predetermined length of 5 mm or less, and fibrillating the cut film by a crumpling and disintergrating action mainly by blows and air whirling stream. A suitable apparatus for such fibrillation is presented. Synthetic pulp thus prepared provides a paper-like material having superior properties by blending it with e.g. wood pulp.

Claims

1. A process for producing a synthetic pulp which comprises:

a. making a composition consisting of

1. 50 to 90 parts by weight of polypropylene having a melt flow rate of 30 to 150 as measured at 230°

C and under a load of 2.16 kg and

2. 50 to 10 parts by weight of low density polyethylene,

into a film having a thickness of 70 μ

or less,

b. uniaxially stretching the resulting film to at least 8 times its original length,

c. cutting the film thus stretched to lengths of 5 mm or less, and

d. fibrillating the cut film lengths by passing them through at least two clearances having a distance of 5 mm or less formed between a plurality of linear projections on the inner peripheral surface of a cylindrical casing and the tip ends of at least two sets of a large number of vanes rotating therein at a peripheral speed of 92 - 100^m /sec. whereby a crumpling and disintegrating action mainly by blows and a whirling air stream is brought about to effect fibrillation, and

e. recovering a synthetic pulp having the following characteristics

3. A process according to claim 1, wherein the low density polyethylene has a melt index of 0.5 to 10 as measured at 190°

C and under a load of 2.16 Kg.

4. A process according to claim 1, wherein the low density polyethylene has a melt index of 1.0 to 3.0 as measured at 190°

C and under a load of 2.16 Kg.

5. A process according to claim 1, wherein the uniaxial stretching is carried out at a temperature of 120°

- 150°

C.

6. A process according to claim 1, wherein the fibrillating is carried out in the presence of a surfactant.

7. A process according to claim 1, wherein said fibrillating is carried out at least once.

9. A process according to claim 5, wherein said surfactant is a dialkyl sulfosuccinate or its salt.

10. A process according to claim 5, wherein said surfactant is polyoxyethylene glycol ether.

11. A process according to claim 1 wherein the fibrillating is carried out in the presence of a dilute aqueous solution of a surfactant at a concentration of 0.5 to 3% by weight of the solution.

2. the fibrils being branched in a developed manner from a trunk,the trunks and fibrils being extended in various large and small creep or snake-like forms along the longitudinal direction thereof,the sizes of the trunks substantially being less than 20 deniers and most of the sizes being less than 5 deniers,as the sizes of the trunks are increased, the width is increased as compared with the thickness,the length of the trunks being less than 5 mm, and the trunks having substantially uniform fiber lengths for any given length,the fibers of each pulp being slightly entangled with one another when collected, andthe pulp being free from small twisted masses caused by firm entanglement of the fibers and free from molten small particles.

8. A process according to claim 2, wherein the uniaxial stretching is carried out under a stretching ratio of 10 - 13 times the original length.