CA1248254A

CA1248254A - Biodegradable material from wood waste suitable for injection molding

Info

Publication number: CA1248254A
Application number: CA000507188A
Authority: CA
Inventors: Pavel Stovicek
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-04-21
Filing date: 1986-04-21
Publication date: 1989-01-03

Abstract

A B S T R A C T
This invention deals with a new plasticized biodegradable, highly fibrous material, suitable for injection molding. This material is producod from wood waste and bark as basic materials.
SUMARY OF THE INVENTION
In accordance with present invention, a thermoplastic material is provided by reacting a bark extract with synthetic or natural latex.
The exact chemical reaction had not been elucidated and I do not wish to be bound to any theory. Theoreticaly several reaction systems can be involved at the same time.
The bark extract may be prepared by many different technologies. All the bark extracts tested, react with natural and synthetic latexes, but with different speed of reaction. The speed of reaction is directly dependant on the type of latex, quantity of solids in extract, PH of reacting media, temperature of reacting media and agitation of reacting components.
The bark - latex material is not used itself as a material for injection molding, but in course of preparation, it is simultaneously filled by already extracted bark residue and organic fibres. After reactions are completed and fibres are completely soaked in emulsion, PH of reaction media is adjusted to proper level, an unabsorbed water is separated and drained. The drained product is dryed to maximum water content of 4%.
Drying can be done in any conventional drying equipment, but vacuum drying is prefered. The dryed material can be used directly for injection molding, in spite of being very light. For correct feeding of injection machine, some method of volume reduction should be employed. One of good methods of volume reduction is use of an extruder with vented barrel. The extruder has to be able to prouce pelleted or spaghetti type of extruded material.

Description

A B S T R A C T
This invention deals with a n~ plasticized biodegradable, highly fibrous rnat_rial, suitable for injection rnolding. This rnaterial is produced frGm wood ~aste and ~r~ as basic rMterials.
S~Y OF THE I~VENTI~

_ In accordance with present invention, a thermoplastic rnaterial is provided by reacting a bark extract wit~ synthetic or natural latex.
me exact chemical reaction had not been elucidated ard I do not wish to be bound to an~ t.~eor~. Theoreticaly several reaction systems can be involved at the saTne tirne.
me bar'~ extract may be pre~ared by rnany different technologies. ~11 the bark extracts tested, react with natural and s~nthetic latexe~, but with different s~eed of reaction. The speed of reaction is directly ~ependant on the type of latex, quantity of solids in extract, PH of reacting r~dia, tem~erature of reacting media and agitation of reacting cGmponen~s.
The b æk - latex material is not used itself as a material for injection molding, but in course o prep æ ation, it is simultaneously filled by already e.~tracted bark residue and organic fibres. ~ter reactions are ccmpleted and fibres æe ccmpletely soaked in emLlsion, PH of reaction media is adjusted to proper level, an unabsorbed water is separated and drained. 5he drained product is dryed to maximum water content of 4~.
Drying can be done in any conventional dr~ing equipment, but vacuum drying is prefered. The dryed material can be used directl~ for injection molding, in spite of being very light. For correct feeding of injection machine, scme method of vol~me reduction should be employed. One of good methods of v~lume reduction is use of an eYtroder with vented barrel. The ~Ytruder has to b2 able to produce pelleted or spaghetti type of ~Ytruded material.

~ '3~
The material after ~Ytrus ~ and cooling can be used directly ~or in-jection molding ~y injection machine e~uiped with ~J~nt~d b~Ir _l and capable of injec~ion presure in e~cess of 10 000 lb/sq".
The biodegradability of t'.~e material can be tailored to suit to use of the product, ma~e fr~m ~his material. l~he alternztion of biodegra-dability can be achieved b~y use of late~es with different degradation properties, by additives w~ch speed up or slaw dc~1n degradation pro-cess, alternation of PH of primary material, increase or decrease of temperature involved in extrusion or injection process.
A~dition of the plastics with lcw melting ten~erature and addition of a glass fibres is possible, because the material is c~mpatible with mos~ of lcw melting point plastics, but this additives will also alter degradabilitv.
Products frcm this biodegradable material degradate in t~o stages.
First stage of de~radation is induced by exposure of the product to moisture for prolonged period of time. The ccmpressed celulosic fibres ccmponent of the material absorbes slowly the water, increases the volume and causes eYtreme tension inside of the product. This inner tension overccmes the strenght of the material and slowly develops crac~s in surrounding material. The possibility of second stage degradation is in progress, when big surface area of cracks is exposed to the att~ck of microorganisms and fu~gi. The degradation process of the material does not release any chemical Follutants to the enviro~ent.
The product frc~ this biodegradable material can be protected from in-fluence of moisture by introduction of protective coat - moisture barrier.
Only in the mcment, when this barrier is broken, the degradation begin.
m e tex~ "biodegradable" is very often indiscrim mately used to refer to ~B various types of envircmen~al degradation, including photodegradation.

- 2 ~ 3'~

Sc~e polymeric materials ma~ be degradat d ~y o~gen ar~ sun light, but this 2~es not mean that those pol~ric materials also '~till ~e assimilated bv microorganis~s.~he te~ "bi æ e ~ le" us~d herein me~n, t~at t~is tr~e of 2~radability is ir.~uc~ by livir~ organis~s, usualy mic~orga~i~ns.
DESC~IPqIC~T OF P~EFr~ED E~OD~TTS

The follcw~ng eYFerimental results are ilustrati~e:
k~L~L P~P.~I5N
Ccm~one~ts 1) Bark - predried and finely ground or pulverised bzr.~ of Douglas - fir, r~estern h.esloc~ estern red cedar, Lodge~ole pine, ~n~elman s?ruce, Red alc~r,Othe~ bar.~s of othe~ species have not be~n teste~, but all barl~s are considered suitable.
2) Fibrous c~monent - wood wast2,saw dust, wcod chips, wood shavings,jute, sisal hump, lin,en, cotton, Fa~m fibres, textile fibres, stra~, grain hu~s, rice hu~s, so~a bean hu~s, cotton seed hu~s, Feat moss, any natural c~elulo-sic fibresJ desintegrated paFer and sugar cane residue.

3) Synthe lc lateY in order of decreasing degradabilit~:
Swift's latex 1448~- vinyl acetate hcmopolymer Union Carbide lateY UC~R 130 ~ - vinyl acetate hom.orolymer Union C3xbi~e latex UC~R 131 ~`- vinyl acetate hcmopolyme~
Union Carbide latQY UC~R 137 @- vinyl aLho~Dl, vi~ l acetate copoly~.er Union Carbide late~x UC~R 367 Q- vinyl acetate - ac~ylic copolymer Swift's la~Y 6113 ~ - vinyl acetate - ethylene copaly~.er Union Carbide lateY UCr~R 503 ~~ 2~ylic-styrene~polyvinyl chloride copol~e~
D~ Chemical lateY Saran 112 ~ - vinylidene chlori~e copol~er were tested..~atural lat~Y from rub~er tree and ~ok-sa-gi~ plant wer9. tested with gcod results too.

4) Hydroxydes: ~monium hydroxyd3 N~ OH, Sodiu-m h~droxyde NaOH, Potassium hydro~yde KOH, Calcium hydroxyde Ca(OH)2.

5) Acids: Sulphuric acid ~2SO~ EIydrochloric acid HCl, Phospho-ric acid ~3P~4, Acetic acid CH3COOH

6) Additivs~: Talk powder, ~iberfill ~ (80~o gla3s fibras, 20~ sty-rane, Poly3tyrene, Elvax ~ , Polyethylene, Polyprop~lene, etc.

7) ~xtractent3: Cold water, Hot watar, Ste~, Ethanol, Isopropano~
~cetone, Ethyleter, ~ethylethyl ketone~ etc.
E ~ A ~ P ~ E
15 litres of water was poursd into small concrete mixer. 100 grams of Calcium hydroxyde (Hydrated lime) was added to produce Calcium milk suspension. In continuous mixing 2666 grams o~ dryed Douglas fir bark powder was introduced to suspension ~ost o~ the solubls parts o~ the bark were extractsd by Calciura hydroxyde~ Extraction was terminatad after the solution contained minimum of 5~ solids.
At that time tamperature of rsacting media was checked up, incre-ased to 25C and 600 ml (mililitres) of Union Carbide latex UCAR
367 ~ were introduced slowly, under continuous mixing, to the sus-pension. Temperature was kept at 25C minim~m and suspension was continuousl~ mixed for one hour, to acomplish the reaction betwesn bark extract and latex. If the reaction was accomplished, 1333grams of dryed wood shavings were added and throughly soaked under conti-nuous mixing for another hour. When wood shavings were throughly ~oaked, 1% so~ution of phosphoric acid was slowly added under con-tinuous mixing, to achieve PH 5 of reacting media, without change for 30 minutes. If P~ of reacting media stayed without change, the content o~ the mixer was damped on separation tray, vibrations GOm-menced to permit unabsorbed water to drain from the matsrial. Tha i ~ water was recyoled ~or further use. If the water wa~ not draining 5~
~rom matarial any more, the material was tran~ered to dr~ing owen and dehumidified to ma~ir~n o~ 4~ mois~ure content (a vacuum dryar was prefered~ but Was no~ available a~ the ~lme of experiment).
Dryed material was then ground to pagg 6 mi.limgtre sieve o~ Cor~mer-cial grainder. The dry grainded ~aterial was directly trang~sred to extruder for eXtrusion. Extrusion o~ material through vented ba~
rel was done at temperature o~ all Zones o~ barrel Set at 150C7 e~cept nozle zone set at 170C. Ex~ruded makerial was peletised and then allowed to cool. A~ter that it waS ready ~or inj eCtion moldin~
The containers 23 mm S~uare, 100 mm long~ 3 mm wall thk. with 3 a-pertures on each side Were produced aS t~st product in singl8 cavi~
mold from thiS material. The teSt Was run on 350 ton KA~AGUCHI ~
injection machine Witll vented barrel. The conditions ~o-r injection as based on results msasured on thiS machine Were as follows:
1) Feed screw should have 2X RP2~s as main scre~, to ensure that main screw iS alwa~s filled With material.
2) Main screw should rotate evenly at a ma~imum speed of 30 R~.
3) Injection presure on main screw should be a minimurn o~ 15 000 ~SI - 1021 Atmospheres.
4) Decompression after injection minimum 20 mm ~milimetres~.
5) 30 mm cushion o~ material in barrel must be maintained.
6) Temperatures of barrel and nozle must be maintained as follows:
Zone 1 - 148 C
Zone 2 - 148 C
Zone 3 - 148 C
Zone 4 - 148 - 154 C

Zone 5 - 148 - 160 o c ~oZ~ - 148 165 c ~ ~ Temperatures depend on spe;d of injection and RPM of main scraw 2~'~
as a result of shear heat. Di~feren~ macnine and differ~nt type of ~crew will have a slightly di~fereat settlng of te~peratures.
7) Injection time is minimum 5 seconds without aocumulator and 3 seconds with accumulator.

8) Cooling time is dependent on latex used, ~or late~ Union Car~
bide UCAR 367 ~ it is 20 seconds.
~ X A M P L E 2 , _ Biodegradable material wa~ produced under conditions of Example l except that inqtead of Douglas fir bark, Hemlock bark was used~
E X A M P L E _~
Biodegradabls material was produced under conditions of Example l except that instead of Douglas fir bark, Thuja plicata bark was used (Western red Cedar)~
X A M P L E ~4 Biodegradable material was produced undsr conditions of Example l except that instead of Douglas fir bark, ~odge pole pins bark was used.
E X ~ M P L E__~
Biodegradable material was produced under conditions of Example 1 except that instead of ~ouglas fir bark, Engelman pruce bark was used.

Biodegradable material was produced under conditions of Example 1 except that instead of Douglas fir barkjRed Alder bark was used.
X A M P ~ E
Biodegradable material was produced under conditions of ~xample 2 except that instead o~ Union Carbide latex UC~R 367 ~ SwiftR la te~ 1~48 ~ was usad.

Biodegradable material was produced under condi~-lons of ~ar~ple 2 except that instead of Union Carbide latsx UCAR 367 (~), latex UCAR 130(~,) was used.
E X A M P L E
~3iodegradable material was produced under conditions of Example 2 except that instead of Union Carbide late~ UCAR 367(~1atex UCAR
131(~)was used.

10 Biodegradable material was produced under conditions of Example 2 except that instead of Union Carbide latex UCAR 367(~, latsx UCAR 137(~ was used.

Biodegradable material was produced under conditions of 3xample 2 except that instead of Union Carbide latex UC~R 367 ~ ,latax UCA.R 503 @ was used.
E X A M P L ~3 12 Biodegradable material was produced undar conditions o~ ~xample 2 except that instead o~ Union Carbide late~ UCAR 367(~) ,Swift la-20 tex 6113 ~) was used.E X A M ~ L E 13 Biodegradable material was produced under conditions of Example 2 except that instead o~ Union Carbide latex UCAR 367 (~), DOW Saran 112 ~) latex ~as used.
E X A M P L ~3 14 Biodegradable material was produced under condition~ of' Example 2 except that instead of Union Carbide latex UGAR 367(~), fresh na-tural rubber latexes from Thailand and Kok-sa-gis latex ~rom ~o-~`
rea were used.

E ~ A M P L E 15 Biodegradable materials were produce~. undsr condition~ of Ecamples 1 to 14, except prior extrusion 510 of ~IBREFI~ , and 10~/o of Sty-rene were added.
E X A M ~ L 3 16 Biodegradable matexials were produced under conditions of Exampl0s 1 to 14, excapt prior extrusion 5% EL~TAX(~ Eth~lene-vinyl acatate were added.
E ~ A M P I. E 11 10 Biodegraadble materials were produced under conditions of Examples 1 to 14,e~cept prior extrusion, 5~ of polypropylene were added.

Biodegradable materials were produced under condibions of Exarlples 1 to 14, except prior extrusion, 5~ of polyethylene were added.

Containers from materials Examples 1 to 14, 25 containers of each material were ;mmersed for 21 days in water.Intake o~ water by containers was recorded daily. The percentage o~ weight increase after 21 days is in table 1.
T A B L E
~atex typel~Veight incraase grams Percent SWIFT 1448 ~)Broken to pieces UCAR 130 ~g) 12.8~ 42.8 UCAR 131(~a 7 47 2409 UCAR 137 (~) 'l.41 2~.7 UC~R 367 ~ 6.72 22.4 SWIFT 6113 (~ 6.37 21.23 ~CA~ 503 ~ ~.49 1~.96 DO,V SAR~N 112 ~) 1.17 3-9 Natural rubber latexes 0.9 3 Weight of dry container 30 gr~ns, F~ Test specimen~ were cut fr~m containers - e~ample~ 1 to 14, 3 qp3-iL~ 8 -~ ~8'~5~
cimen~ or ~ell materlal,3 (three) specimens ~rorn poly3tyrene and 3 (three) ~rom low density polyethylerle 21 000 m,-N~ Thoss speci-mens were te~ed for dsgradation by ~ungi. Thi3 pro~e~-ure requi-res the placement o~ specimens on ~ solia ~g~r grol~lth medium, that is defficient only in carbon The ~nedi~n ~nd sp0cimeils are inoculated with the test microorganism and incubated for (~) three weeks and longer. Any growth, which may ocur is dependent on utilisation o~ the specimen as a carbon source by test orga~
nism. The test flngi consisted o~ mixture ol ASPERGILUS ~G~R, AS~ERGILUS FLAVUS~ CHEATO~U~I GIOBOS~ and P~ .TINUS (PORIA '~
RII). If the specimens showed growth and concurrent loss of wei-ght and mechanical properties - this was considered as good evi-dence of its biodegra~ility. Results o~ the experiment in Table 2 Material type Growth 21 days Loss weight ~ 2 mon.
Natural rubber latexes Inter~ediate 1.1 DOW ~R~N 112 ~ Intermediate 2.12 UCAR 503 ~ Intermediate 2.97 S.~T 6113 ~ Vigorous 4.1 UCAR 367 ~ Vigorous 4.3 UCAR 1~7 ~' Vigorous 4.97 ~CAR 131 ~ Vigirous 4.75 UCAR 130 ~ Vigorous 6.7 S,~FT 1448@~ Vigorous Desintegrated Polystyrene None O
~olyethylene Slight (20 ~) 0 07 Methods as per Example 19, but containers from 3xample 15 were ; used. The results were similar as in Example 19, the ratio o~

~ weight increase correspond to 3xa~pl~ 19 with differenc0 of 2 percentage points across the board.
E ~ A M P L E 22 ~ethods as per Example 19, but containers from Exarnple 16 were uqed. The rasults were similar as in Exarnple lq, the wei~ht increase correspond to Example 19.
E ~ A M P L E 2~
Methods as per Example lq~ but containers from 3xample 17 were used.The results were similar as in Example l~, the ratio of weight increase correspond to Exam le 19 with dif~erence of one (l) percentage point across the board.

~ethods as per 3xample 19, but containers from 3xample 18 were used. ~he resulys were similar as in Exarnple 19, the ratio of weight increase correspond to ~xample lq with di-~ference of one (1) percenta~e point across the board.

Methods as per Example 20, but containers from 3xamples 15, 16, 17 and 18 were used. Results directly correspond to 3xample 20, see Table 2.
It is to be understood, that the specific data and procedures given are for illustration onl~ and not ror limitation; and tha breadth of the invention is as de~ined in the claims.

~ - 10 -

Claims

I C L A I M :

1) An art of manufacture a biodegradable material, produced from a mixtures of substances comprising (a) from about 0.1 to 95 wei-ght percent of bark extract solids, said extract may be in form of pure extract or raw extract containing 99.9 % of bark residue, (b) from about 1 to 95 weight percent of solids of natural or syn-thetic latexes or mixture thereof; (c) from about 0 to 95 weight percent of naturaly occurring biodegradable product, the percenta-ge based on weight of finished material; (d) from about 0 to 90 weight percent of the group consisting of plastics, plasticizing additives, anorganic catalising salts and mixtures thereof.

2) The art of manufacture of claim 1 wherein said bark is a bark from evergreen plants.

3) The art of manufacture of claim 1 wherein said bark is a bark from deciduous plants.

4) The art of manufacture of claim 1 wherein said natural latex is a natural rubber plant latex.

5) The art of manufacture of claim 1 wherein said natural latax is kok-sa-gis latex.

6) The art of manufacture of claim 1 wherein said synthetic la-tex is a vinyl-acetate latex.

7) The art of manufacture of claim 1 wherein said synthetic la-tex is a vinyl alcohol-vinyl acetate latex.

8) The art of manufacture of claim 1 wherein said synthetic la-tex is a vinyl-chloride latex.

9) The art of manufacture of claim 1 wherein said synthetic la-latex is an acrylic latex.

10) The art of manufacture of claim 1 wherein said synthetic la-tex is a styrene-acrylic latex.

11) The art of manufacture of claim 1 wherein said synthetic latex is a vinylidene latex.

12) The art of manufacture of claim 1 wherein said naturaly o-ccurring biodegradable product is wood waste, sawdust, wood chips, wood shavings, sredded wood.

13) The art of manufacture of claim 1 wherein said naturaly oc-curring biodegradable product are celulosic fibres as jute, sisal hump, linen, cotton, palm fibres etc.

14) The art of manufacture of claim 1 wherein said naturaly oc-curring biodegradable product is a straw.

15) The art of manufacture of claim 1 wherein said naturaly oc-curring biodegradable product is a peat moss.

16) The art of manufacture of claim 1 wherein said naturaly oc-curring product is a sugar cane residue.

17) The art of manufacture of claim 1 wherein said naturaly oc-curring biodegradable products are rice hulls, cotton seed hulls, soya been hulls.

18) The art of manufacture of claim 1 wherein said naturaly oc-curring biodegradable product is a wood pulp.

19) The art of manufacture of claim 1 wherein said naturaly oc-curring biodegradable product is a desintegrated paper.

20) The art of manufacture of claim 1 wherein said plastic is a styrene.

21) The art of manufacture of claim 1 wherein said plastic is a ELVAX ? - polyethylene-vinyl-acetate copolymer.

22) The art of manufacture of claim 1 wherein said plastic is a polyethylane.

23) The art of manufacture of claim 1 wherein said plastic is a polypropylene.

24) The art of manufacture of claim 1 wherein said plasticizing additive can be any commercial plasticizing additive on the market.

25) The art of manufacture of claim 1 wherein said anorganic salts - catalysts can be Calcium phosphate, Sodium phosphate, Po-tassium phosphate, Ammonium phosphate, Magnesium sulphate, Potas-sium sulphate, Sodium sulphate, Ammonium sulphate, Magnesium chlo-ride, Calcium chloride and mixtures thereof.

26) The art of manufacture of claim 1 wherein said bark extract may be produced by extraction by organic solvents.

27) The art of manufacture of claim 1 wherein said bark extract may be produced by extraction by anorganic hydroxydes: NaOH, KOH, NH4OH, Ca(OH)2.

28) The art of manufacture of claim 1 wherein said bark extract may be produced by hot water or steam extraction.

29) The art of manufacture of claim 1 by the reaction between bark extract and latexes in water suspension at PH 7 to 14 under conti-nuous mixing.
30) The art of manufacture of claim 1 wherein said reaction bet-ween bark extract and latexes is posible at temperatures 15°C
and higher.
31) The art of manufacture of claim 1 wherein said reaction bet-ween bark extract and latexes is terminated by separation of the water from reacting media; the separation is achieved by decrea-sing PH by an acid, PH value of 3.5 to 6.5 is essential; the acid may be Phosphoric acid, Sulphuric acid, Hydrochloric acid and most of water soluble organic acids.
32) The art of manufacture of claim 1 wherein said preparation of biodegradable material except water separation can be achie-ved in Continuous Feed Pressure Reactor at residence time from

30 seconds to 2 minutes and temperature up to 215° C with correspondung pressure up to 2o atmospheres.

- / - / - / - / -