CA2217530A1 - Articles formed of biodegradable polystyrene - Google Patents

Articles formed of biodegradable polystyrene

Info

Publication number
CA2217530A1
CA2217530A1 CA 2217530 CA2217530A CA2217530A1 CA 2217530 A1 CA2217530 A1 CA 2217530A1 CA 2217530 CA2217530 CA 2217530 CA 2217530 A CA2217530 A CA 2217530A CA 2217530 A1 CA2217530 A1 CA 2217530A1
Authority
CA
Grant status
Application
Patent type
Prior art keywords
parts
starch
polystyrene
material
defined
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA 2217530
Other languages
French (fr)
Inventor
Hongfei Ma
Zhenlin Hu
Mingde Li
Xiang Zhang
Yuhao Li
Ronggen Cai
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SHANGHAI SANLIN DEGRADEABLE RESIN PRODUCTS Co
Original Assignee
SHANGHAI SANLIN DEGRADEABLE RESIN PRODUCTS COMPANY
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G
    • C08J9/00Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/0061Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof characterized by the use of several polymeric components
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUSE OF INORGANIC OR NON-MACROMOLECULAR ORGANIC SUBSTANCES AS COMPOUNDING INGREDIENTS
    • C08K5/00Use of organic ingredients
    • C08K5/04Oxygen-containing compounds
    • C08K5/05Alcohols; Metal alcoholates
    • C08K5/053Polyhydroxylic alcohols
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L25/00Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
    • C08L25/02Homopolymers or copolymers of hydrocarbons
    • C08L25/04Homopolymers or copolymers of styrene
    • C08L25/06Polystyrene
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L3/00Compositions of starch, amylose or amylopectin or of their derivatives or degradation products
    • C08L3/02Starch; Degradation products thereof, e.g. dextrin
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G
    • C08J2325/00Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Derivatives of such polymers
    • C08J2325/02Homopolymers or copolymers of hydrocarbons
    • C08J2325/04Homopolymers or copolymers of styrene
    • C08J2325/06Polystyrene
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G
    • C08J2403/00Characterised by the use of starch, amylose or amylopectin or of their derivatives or degradation products
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2201/00Properties
    • C08L2201/06Biodegradable

Abstract

A biodegradeable foamed composite material comprising 35 - 65 parts w/w polystyrene, 30 - 50 parts w/w starch and 5 - 15 w/w of a cross-linking agent. The cross-linking agent is preferably glycerine, sorbic alcohol or mixtures thereof. The foamed material is used in the form of disposable knives, forks, spoons, plates, lunch boxes which are relatively rapidly biodegradable as to constitute environmentally friendly disposable articles.

Description

CA 02217~30 1997-10-06 ARTICLES FORMED OF BIODEGRADEABLE POLYSTYRENE

FIELD OF THE INVENTION

This invention relates to articles formed of biodegradable, foamed polystyrene-10 starch composite compositions, particularly sheets and domestic eating utensils, bowls, dishes, lunch boxes and the like, formed of said foamed composition.

BACKGROUND TO THE INVENTION

Polystyrene sheets and articles, such as domestic eating utensils, e.g. knives, forks, spoons, plates, bowls, dishes, lunch boxes and the like, are in significant use in the market place. Unfortunately, such polystyrene articles are relatively non-biodegradable and often discarded to form a public hazard and cause environmental pollution.
Starch-based plastics are acceptable to the public and their use and application20 have gradually increased in the market place. To-date, however, the resultantstarch/plastic composite mAtçriAl contains only less than 10% starch and wherein the starch is present only as a means of lowering the cost of raw materials rather than to provide a biodegradable product.
There, thus, remains a need for an improved biodegradable plastics material from25 which the aforesaid articles can be made to enhance their use without causing environmental pollution.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a disposable, biodegradable,foamed starch-polystyrene article having improved biodegradability.

CA 02217~30 1997-10-06 It is a further object of the invention to provide said improved articles havingimproved asthetic appearance.
Accordingly, the invention provides in one aspect a biodegradeable foamed composite material comprising 35 - 65 parts w/w polystyrene, 30 - 50 parts w/w starch 5 and 5 - 15 w/w of a cross-linking agent.
Preferably, the cross-linking agent is a polyhydric alcohol selected from a glycitol and a cyclitol, for example glycerol (glycerine) and sorbic alcohol (sorbitol). The glycerol may be saponified glycerine in this specification and claims.
The composite material of the present invention provides several advantages.
10 First, the enhanced amount of starch present reduces the overall economic cost of the resultant article, since the raw material starch of use in the product of the invention is of an ordinary grade and is relatively cheap in price and abundant. Second, since the starch is in a form of granules within the polymeric matrix, the free starch granules are open to digestion by microorg~ni.~m~ which weaken the structure of the polymeric material to 15 enhance the degradability.
In a further aspect, the invention provides an article formed of a biodegradablefoamed material as hereinabove defined selected from a sheet, eating utensils, bowls, dishes, plates and lunch boxes.
The foamed articles are made by the general process of granulation and mixing of20 the starch, polystyrene and cross-linking agent, which is then fed to an extruder operating at a temperature of between 120~ - 200~C. The extruded material is passed to a mold or sheet drawing apparatus to provide the desired products. Preferably, a vacuum pump cooperates with the mold to remove excess moisture, rapidly, to reduce the presence of visible bubbles. The extruder screw is m~int~ined at, at least 300 rpm. A preferred 25 granulator is a ZSK-58 and of WPC Company. The sheet drawing and final die forming processes are analogous to those for the extrusion and forming of pure polystyrene, known in the art.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In order that the invention may be better understood, preferred embodiments willnow be described by way of example only with reference to the following examples.

CA 02217~30 1997-10-06 Example 1 A composition consisting of 65 parts polystyrene, 30 parts of starch and 5 parts of sorbic alcohol were mixed in and passed through an extruder at a temperature of 150~ -155~ and passed to a die to provide a sheet molding by drawing the extruder composite 5 material. During extrusion and granulation, the long ratio of the extruder was greater than 35:1.
Example 2 Example 1 was repeated except that the raw material mixture consisted of 50 parts of polystyrene, 40 parts of starch and 10 parts of saponified glycerine.
10 Example 3 Example 1 was repeated except that the raw material mixture consisted of 35 parts of polystyrene, 50 parts of starch and 15 parts of a cross-linking agent consisting of 10 parts of glycerine and 5 parts of sorbic acid.
The resultant amounts of the compositions and physical properties of the product15 are shown in Table 1.
Table 1 Component Physical properties Cross- HorizontalThermo- Load Discount.
ExamplePS Starch linking Verticalstability (height) properties No. agent Strength Variation (Mpa) 1 65 30 5 1.14 No defor- 20 times mation 5% nofracture 1.60 No leakage 2 50 40 10 0.80 No evident 10 times deformation 5% no fracture 1.0 No leakage 3 35 50 15 0.48 Slightly 3 times deformed 10% fracture 0.70 Slightly leakea out CA 02217~30 1997-10-06 Table 1 shows that as the starch content increased and the polystyrene content decreased in the resultant composite product, the physical properties of the product decreased. We have found that 30/40 parts of starch content provide a satisfactorily biodegradable product having expandable physical properties.
The biodegradability of the composite composition of the invention was determined as follows.
The test methods involved a surface plate, laborator, method and an outdoor, natural soil burial abandonment method. The test methods and results are described as l 0 follows.
1. Surface Plate Method.
The surface plate method was conducted according to the technical standard of ASTM GM20-90. A test sample was cut into a test block of 3 cm. x 3 cm. x 0.2 cm. and placed on to a substrate dish. A mixed aqueous suspension of fungi and spores at a concentration of 106- 107 units/ml was sprinkled on to the surface of the test sample and the dish covered. The dish was m~int~ined at a temperature of 30 + 1~C at about 95% relative humidity for 28 days. The breeding conditions of the fungi were recorded at regular intervals. The results are shown in Table 2.
2. Soil Burial Method.
A similar test sample of composite material according to the invention was buried in soil and its appearance observed over regular intervals. The results are shown in Table 3.
Table 2 - Surface Plate Method Test No. Growing Time of hypha 7 days 14 days 21 days 28 days 3 1 2- 2+ 3 35 Table 3 - Outdoor Soil Burial Method CA 02217~30 1997-10-06 Treatment conditions Growing time of hypha (days) Remarks Without any coverings on the surface. 1 2 3- 3 Covered by weeds on the surface 2 3 4- 4+ Cracks appear Covered by soil of 1-2 cm. on the surface. 2 3 4- 4+ Cracksappear Put into waste water trench 2 2+ 3- 3 In Tables 2 and 3, the following gradings were applied.
Grade 0 Nogrowth.
Grade l Minor growth(<l 0% surface covered) Grade 2 Mild growth (10-30% surface covered) Grade 3 Moderate growth (30-60% surface covered) Grade 4 Mass growth (>60 surface covered).
From Tables 2 and 3 it can be seen that the composite starch/polystyrene material generally forms visible mildew in the seven days and that the breeding of hypha occurs on the composite surface. After 28 days, the composite material is seriously eroded and cracks are observed. The material in Table 3 had holes which are explained as being caused by insects.
Thus, the results show the relatively fast rate of degradation.

Although this disclosure has described and illustrated certain preferred embo-lim~nt~ of the invention, it is to be understood that the invention is not restricted to those particular embodiments. Rather, the invention includes all embodiments which are 35 functional or mechanical equivalents of the specific embodiments and features that have been described and illustrated.

Claims (8)

1. A biodegradeable foamed composite material comprising 35 - 65 parts w/w polystyrene, 30-50 parts w/w starch and 5 - 15 w/w of a cross-linking agent.
2. A composite material as defined in claim 1 wherein said cross-linking agent is a polyhydric alcohol.
3. A composite material as defined in claim 2 wherein said polyhydric alcohol is selected from sorbic alcohol, glycerine and saponified glycerine.
4. A material as defined in claim l comprising 65 parts w/w polystyrene, 30 parts w/w starch and 5 parts sorbic alcohol.
5. A material as defined in claim 1 comprising 50 parts w/w polystyrene, 40 parts w/w starch and 10 parts w/w/ saponified glycerine.
6. A material as defined in claim 1 comprising 35 parts w/w polystyrene, 50 parts w/w starch, 10 parts glycerine w/w and 5 parts w/w sorbic alochol.
7. A biodegradable foamed material as defined in any one of claims 1 to 6 made by (a) mixing, (b) extruding at a temperature selected from 120° - 200°C and (c) forming a mixture comprising 35 - 65 parts w/w polystyrene, 30 - 50 parts w/w/
starch and a cross-linking agent.
8. An article formed of a biodegradable foamed material as defined in any one ofclaims 1 - 7 selected from a sheet, eating utensils, bowls, dishes, plates and lunch boxes.
CA 2217530 1997-10-06 1997-10-06 Articles formed of biodegradable polystyrene Abandoned CA2217530A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA 2217530 CA2217530A1 (en) 1997-10-06 1997-10-06 Articles formed of biodegradable polystyrene

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA 2217530 CA2217530A1 (en) 1997-10-06 1997-10-06 Articles formed of biodegradable polystyrene

Publications (1)

Publication Number Publication Date
CA2217530A1 true true CA2217530A1 (en) 1999-04-06

Family

ID=4161591

Family Applications (1)

Application Number Title Priority Date Filing Date
CA 2217530 Abandoned CA2217530A1 (en) 1997-10-06 1997-10-06 Articles formed of biodegradable polystyrene

Country Status (1)

Country Link
CA (1) CA2217530A1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010078108A1 (en) * 2008-12-30 2010-07-08 Sabic Innovative Plastics Ip B.V. Flame retardant resinous compositions and process
US7915328B2 (en) 2008-12-30 2011-03-29 Sabic Innovative Plastics Ip B.V. Flame retardant resinous compositions and process
US7939585B2 (en) 2008-01-30 2011-05-10 Sabic Innovative Plastics Ip B.V. Flame retardant resinous compositions and process
WO2011063448A1 (en) * 2009-11-24 2011-06-03 Safeps Pty Ltd A biodegradable expanded polystyrene foam and method for its production

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7939585B2 (en) 2008-01-30 2011-05-10 Sabic Innovative Plastics Ip B.V. Flame retardant resinous compositions and process
WO2010078108A1 (en) * 2008-12-30 2010-07-08 Sabic Innovative Plastics Ip B.V. Flame retardant resinous compositions and process
US7915329B2 (en) 2008-12-30 2011-03-29 Sabic Innovative Plastics Ip B.V. Flame retardant resinous compositions and process
US7915328B2 (en) 2008-12-30 2011-03-29 Sabic Innovative Plastics Ip B.V. Flame retardant resinous compositions and process
JP2012514109A (en) * 2008-12-30 2012-06-21 サビック イノベーティブ プラスチックス イーペー ベスローテン フェンノートシャップ The flame retardant resin composition and its preparation
WO2011063448A1 (en) * 2009-11-24 2011-06-03 Safeps Pty Ltd A biodegradable expanded polystyrene foam and method for its production

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