CA2071078A1 - Thermoplastic photodegradable and biodegradable polymer blend - Google Patents
Thermoplastic photodegradable and biodegradable polymer blendInfo
- Publication number
- CA2071078A1 CA2071078A1 CA 2071078 CA2071078A CA2071078A1 CA 2071078 A1 CA2071078 A1 CA 2071078A1 CA 2071078 CA2071078 CA 2071078 CA 2071078 A CA2071078 A CA 2071078A CA 2071078 A1 CA2071078 A1 CA 2071078A1
- Authority
- CA
- Canada
- Prior art keywords
- blend
- polyisoprene
- polycaprolactone
- parts
- composition
- 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
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L7/00—Compositions of natural rubber
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
- C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L89/00—Compositions of proteins; Compositions of derivatives thereof
- C08L89/005—Casein
Abstract
ABSTRACT
A photodegradable and fully biodegradable plastic material, which can be molded using conventional molding techniques, and which has relatively good properties includes a blend of polyisoprene and polycaprolactone resins. The material biodegrades in soil and sea water environments. All blend ingredients are completely decomposed by microorganisms.
Polyisoprene is a natural polymer present in a large variety of plant species. Polycaprolactone is a synthetic polymer resin known to be decomposed by microorganisms. The plastic material has thermoplastic properties which permits processing of the material using conventional plastic-working techniques.
A photodegradable and fully biodegradable plastic material, which can be molded using conventional molding techniques, and which has relatively good properties includes a blend of polyisoprene and polycaprolactone resins. The material biodegrades in soil and sea water environments. All blend ingredients are completely decomposed by microorganisms.
Polyisoprene is a natural polymer present in a large variety of plant species. Polycaprolactone is a synthetic polymer resin known to be decomposed by microorganisms. The plastic material has thermoplastic properties which permits processing of the material using conventional plastic-working techniques.
Description
2~71~7~
This invention relates to fully biodegradable and photodegradable polymer blends and to methods of making the same.
More specifically, the present invention relates to blends of polyisoprene and polycaprolactone which have thermoplastic properties, and which are biodegradable in soil and sea water environments, and photodegradable.
As a result of concerns about the environment and disposal of waste materials, a great deal of effort has been directed towards the development of biodegradable plastic materials. The main emphasis of such effort has been placed on the mechanisms of photodegradation and biodegradation.
Photodegradation is the decomposition of photosensitive materials initiated by the ultraviolet component of natural light, and biodegradation results from the action of microorganisms such as bacteria, fungi or algae.
Photodegradablity is an inherent property of some polymers and in certain cases it can be enhanced by the use of photosensitizing additives. Photodegradable plastics have found use in applications such as agricultural mulch film, trash bags, and retail shopping bags.
Several different types of plastics have been produced which are fully or partially biodegradable. Some effort has been made to modify non-biodegradable polymers with starch in concentrations of 2-15%. However some controversy remains as to whether such materials are completely - ' : ' : -biodegradable. Some newer materials which use starch as part of the polymer matrix at levels of 60-100~ are reported to be completely biodegradable. Certain polyester polymers have been shown to be biodegradable. These include aliphatic esters such as polyhydroxybutyrate-valerate (PHBV) and polycaprolactone.
Polycaprolactone blends are known which contain a variety of thermoplastic resins including polyethylene, polystyrene and nylon and are degradable in soil or sea water.
However, because of the presence of non-biodegradable resin components, such blends are not completely biodegradable. In addition, the blends do not possess accelerated photo-degradation abilities as measured against the properties of widely used commercial plastics.
The polyisoprene-polycaprolactone blend disclosed by Canadian Patent No. 1,111,179 which issued to Eric G. Kent on on October 20, 1981 is described as having thermoplastic properties. The patented invention is used for molding components of orthopedic devices specifically because of the mechanical and thermal properties of the material. Canadian Patent No. 1,080,875, which issued to Eric G. Kent on July 1, 1980 also describes a blend containing polyisoprene and polycaprolactone. Because of its mechanical properties, the blend is used in the manufacture of sporting goods, specifically golf ball covers. Japanese Patent No. JP
89293048 describes a multi-component biodegradable coating ' 2~71~8 consisting of polycaprolactone, olefinic polymers, wax, petroleum resin and fats and their derivatives including metal salts. The possibility of introducing a natural resin (polyisoprene) into such a coating is mentioned. Moreover, one of the resins mentioned is natural rubber. Fertilizer grains are coated by such a coating, which is degraded by microorganisms in the soil.
None of the above-mentioned patents suggests a composition which is photodegradable or biodegradable in sea water. Only the Japanese patent mentions a composition with the ability to biodegrade in soil. None of the patents suggests using a composition for manufacturing a product using known plastic working methods such as injection molding, extrusion, blow molding or similar techniques which have significant importance in applications for biodegradable and photodegradable plastics.
Known biodegradable polymers have suffered slow acceptance due to limitations in processing and high costs relative to conventional, non-degradable polymers.
An object of the present invention is to provide a plastic material which is completely biodegradable and photodegradable, and which has thermoplastic properties comprising a blend of polyisoprene and polycaprolactone.
Another object of the invention is to provide a biodegradable and photodegradable plastic material comprising a blend of polyisoprene and polycaprolactone which can be used to manufacture articles using conventional plastic processing techniques.
Another object of the invention is to provide a biodegradable and photodegradable article formed from a blend of polyisoprene and polycaprolactone which has improved mechanical properties and performance at high temperatures because of a post-forming radiation treatment.
Yet another object of the invention is to provide a method of making a fully biodegradable and photodegradable plastic article by mixing polyisoprene and polycaprolactone to form a blend, and processing the thus produced blend using conventional plastic working techniques to form the article.
The invention provides a polyisoprene/polycapro-lactone polymer blend having thermoplastic properties which is fully biodegradable in soil and sea water and is photo-degradable.
The polyisoprene/polycaprolactone blend of the invention includes 10 to 500 parts by weight (pbw) of polycaprolactone per 100 pbw polyisoprene resin, preferably 50 to 200 pbw of polycaprolactone per 100 pbw polyisoprene.
Some additivies such as, inter alia, casein, antioxidants, dyes, fillers, vulcanized vegetable oils, fatty acids and pigments commonly used in the plastic and rubber industry may be incorporated into the blends in small amounts.
Polyisoprene can be obtained form natural rubber, or can be produced as a synthetic polymer. Natural rubber contains polyisoprene and is produced by many different plant species. In its natural state, the rubber is biodegradable;
however, the use of stabilization techniques results in reduced biodegradability. Natural rubber, in its pure form, is not acceptable for producing useful products using conventional techniques such as injection and blow molding, and extrusion which are used for thermoplastic polymeric materials. The main reasons for this are the poor flow characteristics of natural rubber, unsuitable mechanical properties, and tackiness prior to vulcanization.
Polycaprolactone is a synthetic polymer resin known to be decomposed by microorganisms. However the applications for polycaprolactone in commercial manufacturing are limited because of its very low melting point of about 71 - 73C and its relatively high price.
The properties of the polyisoprene/polycaprolactone blends of this invention are very different from the properties described above for the individual polymers. The blends have thermoplastic properties which allow processing using conventional plastic working techniques such as injection molding, blow molding and extrusion. The blend has no tackiness and does not stick to a cold metal mold. The flow properties above the softening point of the blend permit processing using known plastic working techniques. A blend in accordance with the invention containing even low levels of polycaprolactone (30%) is capable of being oriented when force is applied, and will significantly increase the tensile modulus and reduce or eliminate the elastic property characteristic of some grades of polyisoprene to levels typical of some commonly used plastics.
The polyisoprene/polycaprolactone blends can be produced using techniques known to be suitable for blending rubber or plastic such as extrusion, two roll milling and Banbury milling. The blending temperature should be above 60C and preferably in the range 65-75C. The thermoplastic resin obtained from the mixing of the two polymers should be ground or pelletized for future use if the resin is intended for injection molding, blow molding or extrusion manufacturing processes. When compression or transfer or transfer molding processes are to be used for manufacturing goods, the resin can be stored in the form of sheets.
Such polyisoprene/polycaprolactone blends have a relatively stable chemical structure when exposed to heat during processing. They can be processed with standard equipment used for injection molding, blow molding, thermoforming, extrusion, compression or transfer molding to manufacture bottles, containers, films, etc.
The manufactured goods produced using the polyisoprene/polycaprolactone blend can be improved by exposing them to electron beam or gamma radiation. Under irradiation, the polyisoprene present in the blend becomes cross-linked, and mechanical properties such as tensile 2~7~ 078 r strength, elongation at break and impact strength are significantly improved, especially when service at elevated temperature is required.
Articles made from polyisoprene/polycaprolactone blends which are placed in soil or sea water will biodegrade at variable rates. The biodegradation rate depends on conditions such as moisture level (soil), air (oxygen) concentration, temperature, presence of microorganisms, etc.
It is expected that there should be no products of degradation other than carbon dioxide and water. An article made from the blends will degrade quickly when exposed to sunlight. The presence of ultraviolet radiation in the sunlight, light intensity and temperature will individually influence the degradation rate.
The following examples describe preferred embodiments of the invention.
30 lb of polyisoprene in the form of natural rubber grade SMR-L was premasticated using a two roll mill at a temperature of 50-75C. After fifteen minutes of mastication, when the temperature rose to 75C, 15 lb of polycaprolactone, in the form of Tone* P-787 Polymer (Union Carbide) was added slowly over an 8 minute period. The blend was mixed at 75C
for the next 5 minutes, as per standard milling procedure, and was then cooled and ground to achieve a particle size of 6-30 *Trademark 2~71~78 mesh blend. The resulting blend is described in the following examples as Blend A.
30 lb of polyisoprene in the form of natural rubber grade SMR-L was mixed with 30 lb of polycaprolactone in the form of Tone 2101 (NL Chemicals). Mixing and grinding were done as described in Example 1 with the exception that the time for addition of the polycaprolactone to the polyisoprene was extended to 12 minutes. The resulting blend is described in the following examples as Blend B.
20 lab of polyisoprene in the form of natural rubber grade SMR-L was mixed with 40 lb of polycaprolactone in the form of Tone P-787 Polymer and 10 oz of Orange* PV-RL 01 (Hoechst). Mixing and grinding were done according to the method of Example 1 with the exception that the time for addition of the polycaprolactone to the polyisoprene was extended to 18 minutes. The blend is described in the following examples as blend C.
30 lb of polyisoprene in the form of natural rubber grade SMR-L was premasticated using a two roll mill at a temperature of 50-95 for 15 minutes. After mastication, when the temperature had risen to 95C, 5 lb of edible technical grade casein (90 Mesh) was added and mixed for another 15 minutes 95C. At this time, the temperature of the blend was *Trademark ~ ' reduced to 75C and 15 lb of polycaprolactone in the form of Tone P-787 Polymer was added slowly over an 8 minute period.
The blend was mixed at 75C for the next 5 minutes, as per standard milling procedure, and was then cooled and ground to achieve a particle size of 6-30 mesh blend. The resulting blend is described in the following examples as Blend D.
An injection molding machine, with a reciprocating screw, was fed with polyisoprene/polycaprolactone Blend A.
The temperature of the heating zones were as follows: Zone 1 - 180C, Zone 2 - 190C, Zone 3 - 200C. The nozzle heater was at 70% capacity. A mold designed to produce test specimens with variable thicknesses, including tensile bars according to ASTM D-638M, was used. The mold was cooled with tap water at 15C. Total shoot size was 23.5 g. The machine was operated using standard procedures for molding plastics.
The moldings obtained showed adequate replication of cavities and good surface finish.
A Keotex KEB-l extruder, with a 50 mm extruding screw, was used for molding 100 ml bottles using polyisoprene/
polycaprolactone Blend C. The temperature of the heating zones were as follows: Zone 1 - 150C, Zone 2 - 170C, Zone 3 -170C. The extrusion head temperature was 190C. The 100 ml bottle mold was cooled was tap water at 15C. The bottles thus obtained had adequate finish and surface quality.
.
A hot press with cooling system was equipped with a mold heated to 120C. 6.5 g of polyisoprene/polycaprolactone Blend B or D was placed in the mold cavity measuring 0.3 mm x 140 mm x 140 mm. The mold was closed under 300 psi pressure, heat was shut down and the cooling system was actuated. A
molding was obtained in the sheet form with no defects and a good surface flnish.
Injection molded specimens in the form of tensile bars (produced according to ASTM D-638M) were obtained using polyisoprene/polycaprolactone Blend A. Specimens were exposed to electron beam (EB) radiation with 120 KGray. Specimens were later tested according to ASTM D-638M for tensile strength and elongation at break at a temperature of 23+2C, together with control specimens not exposed to radiation. The results of testing, which indicate improvement in the mechanical properties of polyisoprene/polycaprolactone Blend A
after exposure to EB radiation, are shown in Table 1.
Blow molded bottles made from polyisoprene/poly-caprolactone Blend C, produced as described in Example 6, and bottles produced from high density polyethylene (HDPE) were placed in exterior conditions in garden soil, approximately 5 cm deep, from late March to late May in Vancouver, B.C. The bottles were inspected at the end of the experiment and tested :
.
2~71 07~
for weight loss, as well as for surface damage visible with the naked eye and under a microscope. The results listed in Table 2 indicate biodegradation of bottles made from polyisoprene/polycaprolactone Blend C. The bottles made from polyethylene were unchanged.
Plastic sheets compression molded from polyisoprene/
polycaprolactone Blend B or D in a similar manner to that described in Example 7, and identical sheets made from HDPE
were immersed in sea water for a period of 30 or 90 days (at water temperature of 10+2C) from the beginning of February to the end of May. The specimen exposure area was screened from direct sunlight. The sheets were inspected at the end of the period and tested for weight loss, change in dimensions, surface damage, and growth of microorganisms visible with the naked eye and under a microscope. The results listed in Table
This invention relates to fully biodegradable and photodegradable polymer blends and to methods of making the same.
More specifically, the present invention relates to blends of polyisoprene and polycaprolactone which have thermoplastic properties, and which are biodegradable in soil and sea water environments, and photodegradable.
As a result of concerns about the environment and disposal of waste materials, a great deal of effort has been directed towards the development of biodegradable plastic materials. The main emphasis of such effort has been placed on the mechanisms of photodegradation and biodegradation.
Photodegradation is the decomposition of photosensitive materials initiated by the ultraviolet component of natural light, and biodegradation results from the action of microorganisms such as bacteria, fungi or algae.
Photodegradablity is an inherent property of some polymers and in certain cases it can be enhanced by the use of photosensitizing additives. Photodegradable plastics have found use in applications such as agricultural mulch film, trash bags, and retail shopping bags.
Several different types of plastics have been produced which are fully or partially biodegradable. Some effort has been made to modify non-biodegradable polymers with starch in concentrations of 2-15%. However some controversy remains as to whether such materials are completely - ' : ' : -biodegradable. Some newer materials which use starch as part of the polymer matrix at levels of 60-100~ are reported to be completely biodegradable. Certain polyester polymers have been shown to be biodegradable. These include aliphatic esters such as polyhydroxybutyrate-valerate (PHBV) and polycaprolactone.
Polycaprolactone blends are known which contain a variety of thermoplastic resins including polyethylene, polystyrene and nylon and are degradable in soil or sea water.
However, because of the presence of non-biodegradable resin components, such blends are not completely biodegradable. In addition, the blends do not possess accelerated photo-degradation abilities as measured against the properties of widely used commercial plastics.
The polyisoprene-polycaprolactone blend disclosed by Canadian Patent No. 1,111,179 which issued to Eric G. Kent on on October 20, 1981 is described as having thermoplastic properties. The patented invention is used for molding components of orthopedic devices specifically because of the mechanical and thermal properties of the material. Canadian Patent No. 1,080,875, which issued to Eric G. Kent on July 1, 1980 also describes a blend containing polyisoprene and polycaprolactone. Because of its mechanical properties, the blend is used in the manufacture of sporting goods, specifically golf ball covers. Japanese Patent No. JP
89293048 describes a multi-component biodegradable coating ' 2~71~8 consisting of polycaprolactone, olefinic polymers, wax, petroleum resin and fats and their derivatives including metal salts. The possibility of introducing a natural resin (polyisoprene) into such a coating is mentioned. Moreover, one of the resins mentioned is natural rubber. Fertilizer grains are coated by such a coating, which is degraded by microorganisms in the soil.
None of the above-mentioned patents suggests a composition which is photodegradable or biodegradable in sea water. Only the Japanese patent mentions a composition with the ability to biodegrade in soil. None of the patents suggests using a composition for manufacturing a product using known plastic working methods such as injection molding, extrusion, blow molding or similar techniques which have significant importance in applications for biodegradable and photodegradable plastics.
Known biodegradable polymers have suffered slow acceptance due to limitations in processing and high costs relative to conventional, non-degradable polymers.
An object of the present invention is to provide a plastic material which is completely biodegradable and photodegradable, and which has thermoplastic properties comprising a blend of polyisoprene and polycaprolactone.
Another object of the invention is to provide a biodegradable and photodegradable plastic material comprising a blend of polyisoprene and polycaprolactone which can be used to manufacture articles using conventional plastic processing techniques.
Another object of the invention is to provide a biodegradable and photodegradable article formed from a blend of polyisoprene and polycaprolactone which has improved mechanical properties and performance at high temperatures because of a post-forming radiation treatment.
Yet another object of the invention is to provide a method of making a fully biodegradable and photodegradable plastic article by mixing polyisoprene and polycaprolactone to form a blend, and processing the thus produced blend using conventional plastic working techniques to form the article.
The invention provides a polyisoprene/polycapro-lactone polymer blend having thermoplastic properties which is fully biodegradable in soil and sea water and is photo-degradable.
The polyisoprene/polycaprolactone blend of the invention includes 10 to 500 parts by weight (pbw) of polycaprolactone per 100 pbw polyisoprene resin, preferably 50 to 200 pbw of polycaprolactone per 100 pbw polyisoprene.
Some additivies such as, inter alia, casein, antioxidants, dyes, fillers, vulcanized vegetable oils, fatty acids and pigments commonly used in the plastic and rubber industry may be incorporated into the blends in small amounts.
Polyisoprene can be obtained form natural rubber, or can be produced as a synthetic polymer. Natural rubber contains polyisoprene and is produced by many different plant species. In its natural state, the rubber is biodegradable;
however, the use of stabilization techniques results in reduced biodegradability. Natural rubber, in its pure form, is not acceptable for producing useful products using conventional techniques such as injection and blow molding, and extrusion which are used for thermoplastic polymeric materials. The main reasons for this are the poor flow characteristics of natural rubber, unsuitable mechanical properties, and tackiness prior to vulcanization.
Polycaprolactone is a synthetic polymer resin known to be decomposed by microorganisms. However the applications for polycaprolactone in commercial manufacturing are limited because of its very low melting point of about 71 - 73C and its relatively high price.
The properties of the polyisoprene/polycaprolactone blends of this invention are very different from the properties described above for the individual polymers. The blends have thermoplastic properties which allow processing using conventional plastic working techniques such as injection molding, blow molding and extrusion. The blend has no tackiness and does not stick to a cold metal mold. The flow properties above the softening point of the blend permit processing using known plastic working techniques. A blend in accordance with the invention containing even low levels of polycaprolactone (30%) is capable of being oriented when force is applied, and will significantly increase the tensile modulus and reduce or eliminate the elastic property characteristic of some grades of polyisoprene to levels typical of some commonly used plastics.
The polyisoprene/polycaprolactone blends can be produced using techniques known to be suitable for blending rubber or plastic such as extrusion, two roll milling and Banbury milling. The blending temperature should be above 60C and preferably in the range 65-75C. The thermoplastic resin obtained from the mixing of the two polymers should be ground or pelletized for future use if the resin is intended for injection molding, blow molding or extrusion manufacturing processes. When compression or transfer or transfer molding processes are to be used for manufacturing goods, the resin can be stored in the form of sheets.
Such polyisoprene/polycaprolactone blends have a relatively stable chemical structure when exposed to heat during processing. They can be processed with standard equipment used for injection molding, blow molding, thermoforming, extrusion, compression or transfer molding to manufacture bottles, containers, films, etc.
The manufactured goods produced using the polyisoprene/polycaprolactone blend can be improved by exposing them to electron beam or gamma radiation. Under irradiation, the polyisoprene present in the blend becomes cross-linked, and mechanical properties such as tensile 2~7~ 078 r strength, elongation at break and impact strength are significantly improved, especially when service at elevated temperature is required.
Articles made from polyisoprene/polycaprolactone blends which are placed in soil or sea water will biodegrade at variable rates. The biodegradation rate depends on conditions such as moisture level (soil), air (oxygen) concentration, temperature, presence of microorganisms, etc.
It is expected that there should be no products of degradation other than carbon dioxide and water. An article made from the blends will degrade quickly when exposed to sunlight. The presence of ultraviolet radiation in the sunlight, light intensity and temperature will individually influence the degradation rate.
The following examples describe preferred embodiments of the invention.
30 lb of polyisoprene in the form of natural rubber grade SMR-L was premasticated using a two roll mill at a temperature of 50-75C. After fifteen minutes of mastication, when the temperature rose to 75C, 15 lb of polycaprolactone, in the form of Tone* P-787 Polymer (Union Carbide) was added slowly over an 8 minute period. The blend was mixed at 75C
for the next 5 minutes, as per standard milling procedure, and was then cooled and ground to achieve a particle size of 6-30 *Trademark 2~71~78 mesh blend. The resulting blend is described in the following examples as Blend A.
30 lb of polyisoprene in the form of natural rubber grade SMR-L was mixed with 30 lb of polycaprolactone in the form of Tone 2101 (NL Chemicals). Mixing and grinding were done as described in Example 1 with the exception that the time for addition of the polycaprolactone to the polyisoprene was extended to 12 minutes. The resulting blend is described in the following examples as Blend B.
20 lab of polyisoprene in the form of natural rubber grade SMR-L was mixed with 40 lb of polycaprolactone in the form of Tone P-787 Polymer and 10 oz of Orange* PV-RL 01 (Hoechst). Mixing and grinding were done according to the method of Example 1 with the exception that the time for addition of the polycaprolactone to the polyisoprene was extended to 18 minutes. The blend is described in the following examples as blend C.
30 lb of polyisoprene in the form of natural rubber grade SMR-L was premasticated using a two roll mill at a temperature of 50-95 for 15 minutes. After mastication, when the temperature had risen to 95C, 5 lb of edible technical grade casein (90 Mesh) was added and mixed for another 15 minutes 95C. At this time, the temperature of the blend was *Trademark ~ ' reduced to 75C and 15 lb of polycaprolactone in the form of Tone P-787 Polymer was added slowly over an 8 minute period.
The blend was mixed at 75C for the next 5 minutes, as per standard milling procedure, and was then cooled and ground to achieve a particle size of 6-30 mesh blend. The resulting blend is described in the following examples as Blend D.
An injection molding machine, with a reciprocating screw, was fed with polyisoprene/polycaprolactone Blend A.
The temperature of the heating zones were as follows: Zone 1 - 180C, Zone 2 - 190C, Zone 3 - 200C. The nozzle heater was at 70% capacity. A mold designed to produce test specimens with variable thicknesses, including tensile bars according to ASTM D-638M, was used. The mold was cooled with tap water at 15C. Total shoot size was 23.5 g. The machine was operated using standard procedures for molding plastics.
The moldings obtained showed adequate replication of cavities and good surface finish.
A Keotex KEB-l extruder, with a 50 mm extruding screw, was used for molding 100 ml bottles using polyisoprene/
polycaprolactone Blend C. The temperature of the heating zones were as follows: Zone 1 - 150C, Zone 2 - 170C, Zone 3 -170C. The extrusion head temperature was 190C. The 100 ml bottle mold was cooled was tap water at 15C. The bottles thus obtained had adequate finish and surface quality.
.
A hot press with cooling system was equipped with a mold heated to 120C. 6.5 g of polyisoprene/polycaprolactone Blend B or D was placed in the mold cavity measuring 0.3 mm x 140 mm x 140 mm. The mold was closed under 300 psi pressure, heat was shut down and the cooling system was actuated. A
molding was obtained in the sheet form with no defects and a good surface flnish.
Injection molded specimens in the form of tensile bars (produced according to ASTM D-638M) were obtained using polyisoprene/polycaprolactone Blend A. Specimens were exposed to electron beam (EB) radiation with 120 KGray. Specimens were later tested according to ASTM D-638M for tensile strength and elongation at break at a temperature of 23+2C, together with control specimens not exposed to radiation. The results of testing, which indicate improvement in the mechanical properties of polyisoprene/polycaprolactone Blend A
after exposure to EB radiation, are shown in Table 1.
Blow molded bottles made from polyisoprene/poly-caprolactone Blend C, produced as described in Example 6, and bottles produced from high density polyethylene (HDPE) were placed in exterior conditions in garden soil, approximately 5 cm deep, from late March to late May in Vancouver, B.C. The bottles were inspected at the end of the experiment and tested :
.
2~71 07~
for weight loss, as well as for surface damage visible with the naked eye and under a microscope. The results listed in Table 2 indicate biodegradation of bottles made from polyisoprene/polycaprolactone Blend C. The bottles made from polyethylene were unchanged.
Plastic sheets compression molded from polyisoprene/
polycaprolactone Blend B or D in a similar manner to that described in Example 7, and identical sheets made from HDPE
were immersed in sea water for a period of 30 or 90 days (at water temperature of 10+2C) from the beginning of February to the end of May. The specimen exposure area was screened from direct sunlight. The sheets were inspected at the end of the period and tested for weight loss, change in dimensions, surface damage, and growth of microorganisms visible with the naked eye and under a microscope. The results listed in Table
3 indicate biodegradation of the sheets made from the polyisoprene/polycaprolactone blends.
Hot-pressed film specimens approximately 0.25 mm (10 mil) made from polyisoprene/polycaprolactone Blend C were placed in a Q W accelerated weathering machine along with linear low density polyethylene (LLDPE - Dupont Sclair 2114) film specimens prepared in similar manner and were tested according to ASTM D4329. UVB-313 lamps were employed to irradiate the specimens with ultraviolet rays. The test 207~078 condition consisted of alternating cycles of 8 hours of UV
light followed by 4 hours of condensation. The temperature for the light cycle was 40C and 50C for the condensation cycle. Sample specimens were tested for tensile strength (TS) and elongation at break (EB) after 200 hours and 400 hours accelerated aging according to ASTM D882. The results are shown in Table 4 and Table 5. The polyisoprene/polycapro-lactone Blend C showed greater loss of tensile strength and elongation at break in comparison with polyethylene.
2~71078 TENSILE PROPERTIES OF SPECIMENS
Specimen Dose Temperature Tensile Strength Elongation No. (kGy) (C) (kg/cm2)At Break (%) 1 120 23 122.2 1355.0 2 0 23 32.1 232.9 DEGRADATION IN GARDEN SOIL OF BOTTLES
MADE FROM BLEND C IN COMPARISON WITH
POLYETHYLENE BOTTLES
BottleExposure WeightWeightWeight Appearance Materials Period Initial After Loss (days) (g)Exposure (g) (g) Blend C 70 13.66112.787 0.874 Extensive surface deterioration and coloniza-tion.
Polyethylene 7013.312 13.294 0.018 No change 2~7~ ~78 DEGRADATION IN SEA WATER OF SHEETS
MADE FROM BLEND B AND D IN COMPARISON
WITH HDPE SHEETS
Sheet ExposureWeight Loss Appearance Materials Periodper 100 cm2 (days) Sample (g)*
Blend B 30 0.07 Deposit of micro-organisms beginning 100 0.26 surface deterioration Blend D 30 0.08 Deposit of micro-organisms beginning 100 0.38 surface deterioration HDPE 30 0 No visible change * Based on one side of specimen.
TENSILE STRENGTH (TS) OF BLEND C IN
COMPARISON WITH LLDPE AFTER
EXPOSURE TO ACCELERATED WEATHERING
Polymer Exposure 200 Hours Exposure 400 Hours TS TS Changes TS TS Changes Initial Final (%) Initial Final (%) kg/cm2 kg/cm2 kg/cm2 kg/cm2 Blend C 192 134 -30 192 78 -59 Polyethylene 125 149 +19 125 99 -21 ..
ELONGATION AT BREAK (EB) OF BLEND C
IN COMPARISON WITH POLYETHYLENE AFTER
EXPOSURE TO ACCELERATED WEATHERING
PolymerExposure 200 Hours Exposure 400 Hours EB EB Changes EB EB Changes Initial Final (%) Initial Final (%) (%) (%) (~
Blend C1120 666 -41 1120 18 -98 Polyethylene 36 17 -53 36 7 -81 SUMMARY
The material described hereinbefore, namely the blend of polyisoprene and polycaprolactone resins, possesses a unique combination of the following properties:
(1) thermoplastic properties that allow the material to be processed using conventional thermoplastic-working techniques; and (2) degradability properties that allow the material to completely degrade following the natural mechanisms of biodegradation and photodegradation.
Blends of the material can be successfully processed using techniques such as injection molding, blow molding, thermoforming, extrusion, compression molding, and transfer molding to produce articles commonly made with thermoplastic resins.
The addition of polycaprolactone to polyisoprene results in increased tensile modulus, and significantly reduced or eliminated elasticity in comparison to the original polyisoprene properties and imparts the ability for polymer orientation. Moreover, polycaprolactone eliminates the problem of polyisoprene sticking to cold metal molds during thermoplastic processing.
Blends of the material will biodegrade in soil or sea water and will photodegrade upon exposure to sunlight, and are expected to generate only carbon dioxide and water as products of degradation.
- .
~ . . ' .: . : .
.
2~71078 The composition of the blends includes 10 to 500 parts hy weight (pbw) of polycaprolactone per 100 pbw polyisoprene, with the preferred range being 50 to 200 pbw polycaprolactone to 100 pbw polyisoprene. Additives commonly used in the plastic and rubber industry may be added to the blends in small amounts in order to enhance properties.
The prior art describes polyisoprene/polycapro-lactone blends which possess thermoplastic properties (see Canadian Patents Nos. 1,080,875 and 1,111,179) but, because of the use of components such as sulphur vulcanized natural rubber or ionomer copolymer, the feature of degradability is not addressed. Manufacturing goods using conventional thermoplastic processes is not mentioned. In the one case where biodegradability is mentioned, (Japanese Patent 89293048), polyisoprene/polycaprolactone comprise a part of a formulation, which does not possess thermoplastic properties, and which is not photodegradable. Hence, the known prior art does not teach combined thermoplasticity and degradability properties.
, .
Hot-pressed film specimens approximately 0.25 mm (10 mil) made from polyisoprene/polycaprolactone Blend C were placed in a Q W accelerated weathering machine along with linear low density polyethylene (LLDPE - Dupont Sclair 2114) film specimens prepared in similar manner and were tested according to ASTM D4329. UVB-313 lamps were employed to irradiate the specimens with ultraviolet rays. The test 207~078 condition consisted of alternating cycles of 8 hours of UV
light followed by 4 hours of condensation. The temperature for the light cycle was 40C and 50C for the condensation cycle. Sample specimens were tested for tensile strength (TS) and elongation at break (EB) after 200 hours and 400 hours accelerated aging according to ASTM D882. The results are shown in Table 4 and Table 5. The polyisoprene/polycapro-lactone Blend C showed greater loss of tensile strength and elongation at break in comparison with polyethylene.
2~71078 TENSILE PROPERTIES OF SPECIMENS
Specimen Dose Temperature Tensile Strength Elongation No. (kGy) (C) (kg/cm2)At Break (%) 1 120 23 122.2 1355.0 2 0 23 32.1 232.9 DEGRADATION IN GARDEN SOIL OF BOTTLES
MADE FROM BLEND C IN COMPARISON WITH
POLYETHYLENE BOTTLES
BottleExposure WeightWeightWeight Appearance Materials Period Initial After Loss (days) (g)Exposure (g) (g) Blend C 70 13.66112.787 0.874 Extensive surface deterioration and coloniza-tion.
Polyethylene 7013.312 13.294 0.018 No change 2~7~ ~78 DEGRADATION IN SEA WATER OF SHEETS
MADE FROM BLEND B AND D IN COMPARISON
WITH HDPE SHEETS
Sheet ExposureWeight Loss Appearance Materials Periodper 100 cm2 (days) Sample (g)*
Blend B 30 0.07 Deposit of micro-organisms beginning 100 0.26 surface deterioration Blend D 30 0.08 Deposit of micro-organisms beginning 100 0.38 surface deterioration HDPE 30 0 No visible change * Based on one side of specimen.
TENSILE STRENGTH (TS) OF BLEND C IN
COMPARISON WITH LLDPE AFTER
EXPOSURE TO ACCELERATED WEATHERING
Polymer Exposure 200 Hours Exposure 400 Hours TS TS Changes TS TS Changes Initial Final (%) Initial Final (%) kg/cm2 kg/cm2 kg/cm2 kg/cm2 Blend C 192 134 -30 192 78 -59 Polyethylene 125 149 +19 125 99 -21 ..
ELONGATION AT BREAK (EB) OF BLEND C
IN COMPARISON WITH POLYETHYLENE AFTER
EXPOSURE TO ACCELERATED WEATHERING
PolymerExposure 200 Hours Exposure 400 Hours EB EB Changes EB EB Changes Initial Final (%) Initial Final (%) (%) (%) (~
Blend C1120 666 -41 1120 18 -98 Polyethylene 36 17 -53 36 7 -81 SUMMARY
The material described hereinbefore, namely the blend of polyisoprene and polycaprolactone resins, possesses a unique combination of the following properties:
(1) thermoplastic properties that allow the material to be processed using conventional thermoplastic-working techniques; and (2) degradability properties that allow the material to completely degrade following the natural mechanisms of biodegradation and photodegradation.
Blends of the material can be successfully processed using techniques such as injection molding, blow molding, thermoforming, extrusion, compression molding, and transfer molding to produce articles commonly made with thermoplastic resins.
The addition of polycaprolactone to polyisoprene results in increased tensile modulus, and significantly reduced or eliminated elasticity in comparison to the original polyisoprene properties and imparts the ability for polymer orientation. Moreover, polycaprolactone eliminates the problem of polyisoprene sticking to cold metal molds during thermoplastic processing.
Blends of the material will biodegrade in soil or sea water and will photodegrade upon exposure to sunlight, and are expected to generate only carbon dioxide and water as products of degradation.
- .
~ . . ' .: . : .
.
2~71078 The composition of the blends includes 10 to 500 parts hy weight (pbw) of polycaprolactone per 100 pbw polyisoprene, with the preferred range being 50 to 200 pbw polycaprolactone to 100 pbw polyisoprene. Additives commonly used in the plastic and rubber industry may be added to the blends in small amounts in order to enhance properties.
The prior art describes polyisoprene/polycapro-lactone blends which possess thermoplastic properties (see Canadian Patents Nos. 1,080,875 and 1,111,179) but, because of the use of components such as sulphur vulcanized natural rubber or ionomer copolymer, the feature of degradability is not addressed. Manufacturing goods using conventional thermoplastic processes is not mentioned. In the one case where biodegradability is mentioned, (Japanese Patent 89293048), polyisoprene/polycaprolactone comprise a part of a formulation, which does not possess thermoplastic properties, and which is not photodegradable. Hence, the known prior art does not teach combined thermoplasticity and degradability properties.
, .
Claims (16)
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:
1. A biodegradable and photodegradable, thermoplastic polymer composition comprising a blend of 10 to 500 parts by weight polycaprolactone per 100 parts by weight polyisoprene.
2. A composition according to claim 1, including 50 to 200 parts by weight polycaprolactone per 100 parts by weight polyisoprene.
3. A composition according to claim 1, including an additive commonly used in the plastic and rubber industry.
4. A composition according to claim 1 or 2, wherein the polyisoprene is in the form of natural rubber.
5. A composition according to claim 1, wherein the flow properties of the composition above the softening point permit processing of the composition using conventional thermoplastic working methods.
6. A composition according to claim 1 which can be permanently oriented by the application of force.
7. A method for making a biodegradable and photodegradable, thermoplastic polymer composition comprising the steps of:
(a) blending 10 to 500 parts by weight polycaprolactone with 100 parts weight polyisoprene at a temperature above 60°C; and (b) processing the resulting polymer blend into a form suitable for further thermoplastic working.
(a) blending 10 to 500 parts by weight polycaprolactone with 100 parts weight polyisoprene at a temperature above 60°C; and (b) processing the resulting polymer blend into a form suitable for further thermoplastic working.
8. A method according to claim 7, wherein 50 to 200 parts by weight polycaprolactone is blended with 100 parts by weight polyisoprene.
9. A method according to claim 7, wherein blending is performed at a temperature of 65 to 75°C.
10. A method according to claim 7, including the step of:
(c) adding a small amount of an additive common in the plastic and rubber industry to the composition.
(c) adding a small amount of an additive common in the plastic and rubber industry to the composition.
11. A method according to claim 10, wherein said additive is selected from the group consisting of casein, antioxidants, dyes, fillers, vulcanized vegetable oils, fatty acids and pigments.
12. A method according to claim 7, including the step of molding the blend to form a biodegradable and photodegradable plastic article.
13. A method according to claim 12, wherein the blend is injection molded.
14. A method according to claim 12, wherein the blend is blow molded.
15. A method according to claim 12, wherein the blend is extruded.
16. A method according to claim 12, including the step of irradiating the article.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2071078 CA2071078A1 (en) | 1992-06-11 | 1992-06-11 | Thermoplastic photodegradable and biodegradable polymer blend |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2071078 CA2071078A1 (en) | 1992-06-11 | 1992-06-11 | Thermoplastic photodegradable and biodegradable polymer blend |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2071078A1 true CA2071078A1 (en) | 1993-12-12 |
Family
ID=4150009
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2071078 Abandoned CA2071078A1 (en) | 1992-06-11 | 1992-06-11 | Thermoplastic photodegradable and biodegradable polymer blend |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2071078A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995015999A1 (en) * | 1993-12-10 | 1995-06-15 | Minister Of National Defence | Thermoplastic photodegradable and biodegradable polymer blend |
| EP0984039A1 (en) * | 1998-03-12 | 2000-03-08 | DAICEL CHEMICAL INDUSTRIES, Ltd. | Lactone-containing resin composition, molded object thereof, and film |
-
1992
- 1992-06-11 CA CA 2071078 patent/CA2071078A1/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995015999A1 (en) * | 1993-12-10 | 1995-06-15 | Minister Of National Defence | Thermoplastic photodegradable and biodegradable polymer blend |
| EP0984039A1 (en) * | 1998-03-12 | 2000-03-08 | DAICEL CHEMICAL INDUSTRIES, Ltd. | Lactone-containing resin composition, molded object thereof, and film |
| EP0984039A4 (en) * | 1998-03-12 | 2002-01-02 | Daicel Chem | Lactone-containing resin composition, molded object thereof, and film |
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