Composite product and a process for producing said product

Patent metadata

Field	Value
Publication number	US-11370894-B2
Application number	US-201615760120-A
Country	US
Kind code	B2
Filing date	Sep 20, 2016
Priority date	Sep 21, 2015
Publication date	Jun 28, 2022
Grant date	Jun 28, 2022

Abstract

The present invention relates to a method of making a foamed cellulosic fiber-thermoplastic composite article. The method includes the steps of providing a copolymer composition, combining the copolymer composition and cellulosic fibers, applying heat, mixing energy and pressure to form a foamable mixture, and forming the foamable article in a molding or extruding operation. The method is characterized in that at least 10% of the cellulosic fibers have been thermally modified prior to being combined with the copolymer composition.

First claim

The invention claimed is:

1. A method of making a foamed cellulosic fiber-thermoplastic composite article comprising:
A) providing a copolymer composition that includes:
i) at least about 20 wt. % of a copolymer formed by polymerizing a mixture comprising:
a) about 51% to about 99.9% by weight of one or more primary monomers, and
b) about 0.1% to about 49% by weight of one or more anhydride containing monomers;

B) combining about 30% to about 99.9% by weight of the copolymer composition with about 0.01% to about 70% by weight of one or more cellulosic fibers based on the weight of the combination;
C) applying an amount of heat, mixing energy and pressure sufficient to:
i) mix the copolymer composition and the cellulosic fibers;
ii) react anhydride groups in the copolymer with hydroxyl groups in the cellulosic fibers; and
iii) produce a blowing agent as a byproduct of the reaction in ii) and provide a foamable mixture of the copolymer composition and the cellulosic fibers; and

D) forming the foamed article by placing the foamable mixture in a molding or extruding operation;
wherein the foamed article has a structured foam central portion and micro foamed outer portion that surrounds the structured foam portion and has a higher density than the structured foam central portion;
wherein the micro foamed outer portion comprises from about 5 to about 22 percent of an overall thickness of the foamed article;
wherein at least 10% of the cellulosic fibers of B) were thermally modified to reduce an amount of available hydroxyl groups prior to being combined with the copolymer composition and wherein at least 5% of the cellulosic fibers of B) were not thermally modified, and,
wherein the thermal modification of the cellulosic fibers is performed by heating at a temperature of from 160° C. to 250° C. at atmospheric pressure or at a temperature of from 120° C. to 230° C. at a pressure higher than atmospheric pressure.

2. A method according to claim 1 , wherein the cellulosic fibers have been thermally modified by heat treatment at a temperature from 160 to 250° C. at atmospheric pressure.

3. A method according to claim 1 , wherein at least 30% of the cellulosic fibers have been thermally modified prior to being combined with the copolymer composition.

4. A method according to claim 3 , wherein at least 50% of the cellulosic fibers have been thermally modified prior to being combined with the copolymer composition.

5. A method according to claim 3 , wherein the thermally modified cellulosic fibers are mixed with the non-thermally modified cellulosic fibers prior to being combined with the copolymer composition.

6. The method according to claim 1 , wherein the foamed article has a density of not more than 1.3 g/cm 3 .

7. The method according to claim 1 , wherein the primary monomers are selected from the group consisting of styrenic monomers and olefinic monomers and combinations thereof.

8. The method according to claim 7 , wherein the styrenic monomers are selected from the group consisting of styrene, p-methyl styrene, α-methyl styrene, tertiary butyl styrene, dimethyl styrene, nuclear brominated or chlorinated derivatives thereof and combinations thereof and the olefinic monomers are selected from the group consisting of ethylene; propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene; 2-butene; 2-pentene; 2-hexene; 2-octene; and combinations thereof.

9. The method according to claim 1 , wherein the anhydride containing monomers include one or more monomers according to Formulas I and II: wherein R 1 , R 2 and R 4 are each independently H or a C 1 -C 8 linear, branched or cyclic alkyl or alkenyl radical and R 3 is a C 1 -C 8 linear or branched alkyl group—

10. The method according to claim 1 , wherein the other monomers are one or more selected from the group consisting of divinylbenzene; conjugated dienes; C 1 -C 12 linear, branched or cyclic alkyl mono- or di-esters of maleic acid, fumaric acid and itaconic acid; C 1 -C 12 linear, branched or cyclic alkyl esters of acrylic acid, C 1 -C 12 linear, branched or cyclic alkyl esters of methacrylic acid; acrylonitrile; methacrylonitrile; and combinations thereof.

11. The method according to claim 1 , wherein the weight average molecular weight of the copolymer is from about 20,000 to about 1,000,000.

12. The method according to claim 1 , wherein the elastomeric polymers are selected from the group consisting of homopolymers of butadiene or isoprene; random, block, AB diblock, or ABA triblock copolymers of a conjugated diene with a styrenic monomer and/or acrylonitrile; ABS; copolymers of C 1 -C 12 linear, branched or cyclic olefins and C 1 -C 12 linear, branched or cyclic alkyl esters of (meth)acrylic acid, diblock and triblock copolymers of styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene, styrene-isoprene-styrene, partially hydrogenated styrene-isoprene-styrene and combinations thereof.

13. The method according to claim 1 , wherein the cellulosic fibers have a diameter of at least 0.1 μm.

14. The method according to claim 1 , wherein the foamable mixture comprises one or more additives selected from the group consisting of heat stabilizers, light stabilizers, plasticizers, dyes, pigments; anti-blocking agents; slip agents; lubricants; coloring agents; antioxidants; ultraviolet light absorbers; fillers; anti-static agents; impact modifiers, antimicrobial agents, and combinations thereof.

15. The method according to claim 1 , wherein the copolymer and elastomeric copolymer are combined by melt blending.

16. The method according to claim 1 , wherein the copolymer composition and cellulosic fibers are combined by melt blending.

17. The method according to claim 1 , wherein the copolymer, cellulosic fiber and optional elastomeric polymers and/or optional other additives are dry blended and added to an extruder.

18. The method according to claim 1 , wherein the copolymer and optionally the elastomeric polymer are added to a first extruder and then combined with the cellulosic fiber and optional other additives in a second extruder.

19. The method according to claim 1 , wherein the combination of the copolymer composition and cellulosic fibers is extruded by melt mixing at a temperature sufficient for the copolymer to flow and extruding the combination through an extruder die one or more times.

20. The method according to claim 1 , wherein the extruding operation comprises one or more single-screw extruders and/or twin-screw extruders.

21. The method according to claim 20 , wherein the extruding operation comprises maintaining sufficient pressure in one or more extruders to prevent the blowing agent from escaping from the foamable mixture.

22. The method according to claim 1 , wherein the byproduct blowing agent is selected from the group consisting of water vapor, carbon dioxide or combinations thereof.

23. The method according to claim 1 , wherein the extruding operation comprises discharging the foamable mixture from an extruder into a die or other shaping device that causes the foamable mixture to expand to form a foamed article having a desired shape and or dimension.

24. The method according to claim 1 , wherein the molding operation comprises:
A) feeding the foamable mixture into an extruder to form pellets;
B) placing the pel

Assignees

• Stora Enso Oyj
• Univ Maine System

Inventors

• Mayes Duncan
• Pynnonen Janne
• West Christopher H
• Gardner Douglas J
• Han Yousoo

Classifications

• C08J9/34 Primary

  Chemical features in the manufacture of articles consisting of a foamed macromolecular core and a macromolecular surface layer having a higher density than the core · CPC title

• C08J2401/02

  Cellulose; Modified cellulose · CPC title

• B29K2025/08

  Copolymers of styrene, e.g. AS or SAN, i.e. acrylonitrile styrene (B29K2055/02 takes precedence) · CPC title

• C08J9/0061

  characterized by the use of several polymeric components · CPC title

• C08J2325/08

  Copolymers of styrene (C08J2329/08, C08J2335/06, C08J2355/02 take precedence) · CPC title