KR100346998B1 - Additive composition for promoting the degradation of polymer - Google Patents

Abstract

The present invention relates to an additive composition for promoting decomposition of a polymer and a degradable polymer composition comprising the additive composition, and more particularly, 0.01 to 2.0 parts by weight of a transition metal salt in which an anion is an organic acid, saturated fatty acid, unsaturated fatty acid or substituted fatty acid. ; At least one selected from the group consisting of C ₄ to C ₂₂ unsaturated fatty acids, C ₄ to C ₂₂ unsaturated fatty acids, unsaturated natural polymers having a weight average molecular weight of 10,000 to 3,000,000 and unsaturated synthetic polymers having a weight average molecular weight of 2,500 to 2,000,000 0.1-3.0 parts by weight of unsaturated organic compound; It relates to a polyolefin or polystyrene-promoting additive composition comprising 40-98 parts by weight of a polymer which is at least one of a group consisting of polyethylene, polypropylene, polystyrene, polyethylenepropylene, polyethylenestyrene, polypropylenestyrene, polyethylenepropylenestyrene.

According to the present invention, it is possible to provide an additive composition for a polymer having a suitable balance between the shelf life of the polymer, the functionality and the proper degradability in the environment, and a polymer composition using the additive.

Description

Additive composition for promoting the degradation of polymer

The present invention relates to an additive composition for promoting decomposition of a polymer and a degradable polymer composition comprising the additive composition, and more particularly, 0.01 to 2.0 parts by weight of a transition metal salt in which an anion is an organic acid, saturated fatty acid, unsaturated fatty acid or substituted fatty acid. ; At least one selected from the group consisting of C ₄ to C ₂₂ unsaturated fatty acids, C ₄ to C ₂₂ unsaturated fatty acids, unsaturated natural polymers having a weight average molecular weight of 10,000 to 3,000,000 and unsaturated synthetic polymers having a weight average molecular weight of 2,500 to 2,000,000 0.1-3.0 parts by weight of unsaturated organic compound; It relates to a polyolefin or polystyrene-promoting additive composition comprising 40-98 parts by weight of a polymer which is at least one of a group consisting of polyethylene, polypropylene, polystyrene, polyethylenepropylene, polyethylenestyrene, polypropylenestyrene, polyethylenepropylenestyrene.

Plastic products made from stable or stabilized polymers such as polyethylene (PE), polypropylene (PP) and polystyrene (PS) have durability and stability. However, in the case of heavy use of plastic products such as in agriculture, such durability is often undesirable due to waste problems which can cause serious environmental pollution. For this reason, there is an urgent need for degradable plastic products, and degradable products have been developed.

There are two approaches to degradable plastics. The first is to use biodegradable polymers and the second is to add decomposition promoters to conventional thermoplastic polymers.

However, in the first method, the use of biodegradable polymers such as starch made of thermoplastic has been limited in its success rate. This is because the sensitivity to moisture is so great that the functionality was not as good as that of conventional plastics. As a result of efforts to overcome these drawbacks, relatively expensive materials have been developed (see US Pat. Nos. 5,462,982 and 5,314,934).

On the other hand, the second method is to add an additive that promotes the decomposition of the polymer, and the commonly used additive is a pro-oxidant. The main problem with this method is that it is difficult to strike the right balance between shelf life, functionality and proper degradability in the environment in use. Another problem is that the degradation of the polymer depends on oxygen and the rate of oxygen penetration into the plastic polymer limits the rate of degradation (see US Pat. Nos. 5,854,982 and 5,314,934).

Accordingly, the present inventors have intensively researched to overcome the problems of the prior arts. As a result, the present inventors have applied a polyethylene, polypropylene or polystyrene composition by adding an additive composition comprising a biodegradable polymer or a drying agent to the metal salt and the unsaturated material. In the case of manufacture, it was confirmed that the shelf life, functionality and appropriate degradability in the environment to complete the present invention.

Accordingly, it is an object of the present invention to provide additive compositions for polymers that have a suitable balance between shelf life, functionality and proper degradability in the environment.

It is a further object of the present invention to provide a polymer composition having a suitable balance between shelf life, functionality and suitable degradability in the environment comprising the additive composition.

In order to achieve the above object, the present invention is 0.01 to 2.0 parts by weight of transition metal salt anion is an organic acid, saturated fatty acid, unsaturated fatty acid or substituted fatty acid; At least one selected from the group consisting of C ₄ to C ₂₂ unsaturated fatty acids, C ₄ to C ₂₂ unsaturated fatty acids, unsaturated natural polymers having a weight average molecular weight of 10,000 to 3,000,000 and unsaturated synthetic polymers having a weight average molecular weight of 2,500 to 2,000,000 0.1-3.0 parts by weight of unsaturated organic compound; Provided is a degradation promoting additive composition of polyolefin or polystyrene comprising 40-98 parts by weight of a polymer which is at least one of a group consisting of polyethylene, polypropylene, polystyrene, polyethylenepropylene, polyethylenestyrene, polypropylenestyrene, and polyethylenepropylenestyrene.

In order to further accelerate the decomposition of the polymer, a polymer composition comprising 25 to 49 parts by weight of the homopolymer composition and 25 to 49 parts by weight of the composition of the copolymer is preferable.

In the additive composition, it is preferable to further include 0 to 50 parts by weight of the biodegradable polymer or further include 0 to 5 parts by weight of the desiccant.

In the said additive composition, it is preferable to contain 0-5 weight part of fillers further.

Hereinafter, the composition of this invention is demonstrated more concretely centering on the component.

In the additive composition, it is preferable to use at least one of a group consisting of cobalt, manganese, copper, vanadium and iron as the transition metal of the transition metal salt. The organic acid may be at least one selected from the group consisting of acetic acid, citric acid and tartaric acid, and the saturated fatty acid may be at least one selected from the group consisting of lauric acid, palmitic acid and stearic acid, and the unsaturated fatty acid may be oleic acid, linoleic acid or linolenic acid. And at least one of the group consisting of erucic acid, it is preferable to use 12-hydroxy stearic acid as the substituted fatty acid.

Metal salts play a role in promoting oxidation and photolysis. It may be desirable to include metal salts that can accelerate photolysis predominantly, such as iron-based compounds, for products that can be trash, and where there is no direct sunlight, such as magnesium-based compounds, for products that should be composted. It is preferred to include metal salts which can predominantly accelerate thermal oxidation.

In the additive composition, the unsaturated organic compound is C ₄ ~ C ₂₂ unsaturated fatty acid, C ₄ ~ C ₂₂ unsaturated fatty acid ester, unsaturated natural polymer having a weight average molecular weight of 10,000 ~ 3,000,000 and unsaturated with a weight average molecular weight of 2,500 ~ 2,000,000 At least one of the group consisting of synthetic polymers.

The unsaturated organic compound mainly serves to accelerate thermal decomposition. The use of unsaturated organic compounds to accelerate this thermal decomposition was raised in the 1970s, when soybean oil or other unsaturated oils were proposed. However, the availability of unsaturated sites of such fats and oils is relatively limited compared to unsaturated fatty acids or isoprene-based polymers. Therefore, in the present invention, unsaturated natural polymers such as unsaturated fatty acids, unsaturated fatty acid esters, and isoprene-based polymers or unsaturated synthetic polymers having relatively high solubility are used as the unsaturated substances. The choice of the optimal unsaturated additive can be made in consideration of other criteria such as cost, functionality and odor.

In the additive composition, a natural polymer or a synthetic polymer is used as the biodegradable polymer.

Natural polymers include starch, starch derivatives, cellulose, cellulose derivatives, wood fiber, chitosan, plant-derived proteins such as soy protein, casein, casein salts, or animal-derived proteins such as gelatin.

The starch may be any starch that is natural, whether processed, chemically modified or processed, including starch such as wheat starch, corn starch, potato starch or rice starch. Starch may also be derived from plants such as cassava, tapioca and peas. Starch is a starch in which modified starch, such as chemically treated and crosslinked starch, or a hydroxyl group is substituted with an organic acid to the extent of substitution in the range of 0 to 3 to produce an ester or an organic alcohol to produce an ether.

The cellulose and cellulose derivatives include cellulose compounds such as wood flour or wood fibers derived from plant origin such as grass and grains. Such cellulose may be chemically modified to substitute esters with organic acids at a degree of substitution in the range of 0 to 3 to produce esters, and celluloses may be substituted with organic alcohols to produce ethers.

The biodegradable synthetic polymers include aliphatic polyesters produced by condensation polymerization of HO-A-OH and HOOC-B-COOH, and aliphatic polyesters produced by ring-opening polymerization of caprolactone having 2 to 20 carbon atoms. , Aliphatic polyesters produced by self-condensation polymerization of HOOC-D-OH and aliphatic / aromatic polyesters produced by condensation polymerization of HO-E-OH and HOOC-G-COOH. (A, B, D, E is C _{2 ~ 20} alkylene group, G is a C _{6 ~ 20} arylene or alkyl-arylene)

The incorporation of the biodegradable polymer can promote the transport of oxygen to the center of the polymer, thereby accelerating the oxidation of the polyolefin or polystyrene. However, promoting oxygen transport due to the incorporation of such biodegradable polymers is essential to balance the methods used to achieve functionality.

In the above additive compositions, many natural polymers and some synthetic polymers are hygroscopic, which may cause problems in the plastic product manufacturing process and its functionality. To overcome this problem, a desiccant such as calcium oxide is added. Typical examples of the desiccant include calcium oxide, and magnesium perchlorate and phosphorus pentoxide.

In the additive composition, in addition to a method of incorporating a biodegradable material, there is a method capable of accelerating the oxidation rate of polyolefin and polystyrene by promoting oxygen transport. Thus, the additive composition preferably further comprises 0 to 5 parts by weight of an inert and insoluble (at polymer processing temperature) filler such as calcium carbonate, mica, silica, alumina, or silica-based material. Incorporation of the filler into the polymer can accelerate the rate of penetration of oxygen, particularly when the thermoplastic material is elongated in the molten or semi-melt state. This stretching can occur as bubbles rise in the machine in the transverse direction during the conventional film blowing process and also in thermoforming processes where the sheet is significantly expanded.

In order to achieve another object of the present invention, the present invention is an additive composition of 3 to 50 parts by weight and at least one of the group consisting of polyethylene, polypropylene, polystyrene, polyethylene propylene, polyethylene styrene, polypropylene styrene, polyethylene propylene styrene It provides a polymer composition comprising 50 to 97 parts by weight.

In the polymer composition, the optimum oxygen migration into the plastic product is made by the incorporation of inert and insoluble fine particles and the selection of the thermoplastic polymer. Depending on the plastic product produced and its thickness, the components of the polymer composition are proportioned. For example, in thin plastic products, the amount of particles is limited because there may be sufficient oxygen transport. However, for thick sheets (larger than 30 microns) and injection molded articles, it is necessary to contain a mixture of particulate and the appropriate copolymer.

It is preferred that the polymer composition uses an antioxidant combination of polymers at an appropriate level, as has been described for other oxidation promoter systems to date. This allows to obtain the required shelf life and decomposition products. The antioxidants include ketone-amine antioxidants, aldehyde-amine antioxidants, phenylnaphthylamine antioxidants, substituted diphenylamine antioxidants, paraphenylene-diamine derivative antioxidants, and substituted phenolic oxidation agents. Antioxidants, phenylalkane-based antioxidants, phenyl sulfide-based antioxidants, and phosphite-based antioxidants, which are contained within the let down polymer.

The polymer composition makes it possible to produce plastic products with very good functionality which is essentially the same as the previous products, and to enable decomposition as desired.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention, and the scope of the present invention is not to be construed as being limited by these examples.

Example 1 (Preparation of Promoting Degradation Additive Composition-1)

The additive composition was mixed at 160 DEG C by mixing 0.04% by weight of magnesium stearate, 1.2% by weight of polyisoprene, 2.0% by weight of starch, 0.4% by weight of calcium oxide, 96.36% by weight of linear low-density polyethylene containing 200 ppm of Irganox 1010 and 600 ppm of Irgafos. Prepared.

Example 2 (Preparation of Promoted Degradation Additive Composition-2)

For the raw material of the injection molded product having a thickness of 0.5mm, a polymer composition degradable was prepared at the following mixing ratio.

0.02% by weight magnesium stearate

0.6 wt% polyisoprene

-50.0% by weight of wood fiber

Calcium oxide 5.0 wt%

22.19 wt% polypropylene homopolymer

22.19 weight% propylene-ethylene copolymer having 3% ethylene repeating units

Example 3

In order to test the effect of the additive composition of the present invention, a degradability test of the composition prepared in the above Examples was carried out.

Two transparent films were prepared by mixing 10 wt% and 20 wt% of the additive composition prepared in Example 1 to LDPE (low density polyethylene). The thickness of the film was about 30 micrometers. The material was sent to the SP Swiss National Test and Research Institute in the first week of June 2000 for commissioning.

Example 4 (analysis)

This test is to evaluate the kinetics of thermal-oxidative decomposition of the film prepared in Example 3. The rate of decomposition may vary depending on the type and amount of polymer, additives, temperature and amount of oxygen. The main purpose is to find out the relationship between temperature, oxygen content and time required for the production of biodegradable low molecular oxides.

Heat-oxidation was generally performed at 50, 60 and 70 ° C. at which temperatures decomposition could occur. Oxygen content as well as temperature was varied using air and oxygen / nitrogen mixtures (air, 10% oxygen, 20% oxygen).

The effect of heat-oxidation was assessed by tracking changes in molecular weight using SEC (size exclusion chromatography) measurements.

In this test, the molecular weight of the sample was measured using SEC after various passages of time. SEC measurements were performed at the Department of Polymer Science and Engineering, Chalmers Institute of Technology. The sample was dissolved at 135 ° C. for 16 hours using 1,2,4-trichlorobenzene as a solvent and analyzed at a concentration of 1 g / l.

The test results are as follows.

Table 1 below shows the change in weight average molecular weight when the additive composition is 10% by weight.

Table 1 (Weight average molecular weight of the material before aging: 79400)

Table 2 below shows the change in the number average molecular weight when the additive composition is 10% by weight.

Table 2 (Number average molecular weight of material before aging: 11150)

Table 3 below shows the change in weight average molecular weight when the additive composition is 20% by weight.

Table 3 (Weight average molecular weight of the material before aging: 74300)

Table 4 below shows the change in the number average molecular weight when the additive composition is 20% by weight.

Table 4 (Number average molecular weight of material before aging: 12330)

Referring to Tables 1 to 4, it can be seen that the test substance decomposes rapidly at all temperatures tested. The rate of thermal oxidative decomposition depends on the temperature, the amount of oxygen and the amount of decomposition promoting additive. Temperature seems to be the most important factor. Mw values of both materials are less than 5000 after 2 weeks at 70 ° C. The content of the decomposition promoter is also important. The material containing 20% of the accelerator has a molecular weight value of about 30-50% lower than the corresponding value of the material containing 10% of the promoter. The amount of oxygen seems to have the least effect. No significant effect was observed when 10% of the decomposition promoting additive composition was contained.

Example 5

About 25 g of two biodegradable polymer foils were prepared by mixing 10 wt% and 20 wt% of the degradation accelerator additive composition prepared in Example 1 in LDPE. This polymer foil was pre-aged in an oven at 70 ° C. for 4 weeks. Using this preliminary aged material, the following mineralization test was conducted.

Mineralization of the biodegradable polymer foil occurred at a culture temperature of 60 ° C. in the soil column. This mineralization was investigated by measuring the amount of carbon dioxide produced. The correct amount of test substance was mixed with microbially activated soils containing very little decomposable carbon compounds. This mixture was filled into a glass column. Microorganisms in the soil break down organic compounds (test substances) to produce new biomass. Oxygen was constantly blown into the soil column. When the carbon dioxide produced by the microorganisms was discharged out of the glass column, the gas was washed with the adsorption solution. The carbon dioxide produced was changed from sodium hydroxide solution to sodium carbonate. Fractions of sodium hydroxide solution were taken periodically to determine the carbonic acid content by titration.

The carbon content of the test compound was measured before the mineralization reaction test. Once the carbon content of the test compound is known, the theoretical content of carbon dioxide that can be produced from carbon in the test substance can be assessed. The degree of mineralization of the test compound can be calculated from the carbon dioxide produced.

The weaponization test was conducted from May 17, 20001 to July 18, 2001 (9 weeks). The experimental results are summarized in Tables 5 and 6 below.

Table 5. Mineralization in Soil Columns

Table 6

* 1% CO ₂ production; Comparison with theoretical content

* 2% CO ₂ production; Modified value assuming glucose is completely mineralized with carbon dioxide and biomass

During 9 weeks of incubation, 34% of the carbon in the polymer material containing 10% by weight of the accelerator was converted to carbon dioxide.

During 9 weeks of incubation, 33% of the carbon in the polymer material containing 20% by weight of the accelerator was converted to carbon dioxide.

Only carbonated carbon (which produces CO ₂ ) was measured, and assimilated carbon (which produces biomass) was not measured.

Referring to Table 5 and Table 6, it can be seen that the mineralization rate within 9 weeks in the experiment is 34% and 33%, respectively. According to DIN-Pre-Standard 54900 (1998) (determining the degradability of polymer materials; evaluating the complete biodegradability of polymer materials in Test No. 2 laboratory tests), within 180 days at least 60% of carbon is inorganicized with carbon dioxide and assimilated into biomass If so, the condition will be met. This level was not reached after 9 weeks of culture. However, decomposition still continued. If the material continues to be inorganic at the actual rate of inorganicization, it can be expected that the material will be converted to carbon dioxide within 60 to 90 days of subsequent culture.

The mineralization process is faster at higher temperatures. Industrial decomposition processes occur at temperatures of 80 ° C. Therefore, under such suitable conditions, the material can be estimated to decompose twice as fast.

As described above, according to the present invention, it is possible to provide an additive composition for a polymer having a suitable balance between the shelf life of the polymer, the functionality and the proper degradability in the environment, and a polymer composition using the additive.

Claims (14)

In the decomposition-promoting additive composition of polyolefin or polystyrene, 0.01 to 2.0 parts by weight of a transition metal salt whose anion is an organic acid, saturated fatty acid, unsaturated fatty acid or substituted fatty acid; At least one selected from the group consisting of C ₄ to C ₂₂ unsaturated fatty acids, C ₄ to C ₂₂ unsaturated fatty acids, unsaturated natural polymers having a weight average molecular weight of 10,000 to 3,000,000 and unsaturated synthetic polymers having a weight average molecular weight of 2,500 to 2,000,000 0.1-3.0 parts by weight of unsaturated organic compound; An additive composition comprising 40-98 parts by weight of a polymer which is at least one of a group consisting of polyethylene, polypropylene, polystyrene, polyethylenepropylene, polyethylenestyrene, polypropylenestyrene, and polyethylenepropylenestyrene. The polymer composition of claim 1, wherein the polymer has a homopolymer of 20 to 49 parts by weight and a copolymer of 20 to 49 parts by weight. The additive composition according to claim 1, further comprising 0.01 to 50 parts by weight of the biodegradable polymer. The additive composition of claim 1, further comprising 0.01 to 5 parts by weight of a desiccant. 5. A composition according to claim 4, wherein said desiccant is calcium oxide. The additive composition of claim 1, further comprising 0.01 to 5 parts by weight of at least one inert and insoluble material of the group consisting of calcium carbonate, mica, silica, and alumina. The additive composition of claim 1, wherein the transition metal ion is at least one ion of a group consisting of cobalt, manganese, copper, vanadium, and iron. The composition of claim 1, wherein the organic acid is at least one of a group consisting of acetic acid, citric acid and tartaric acid. The composition of claim 1, wherein said saturated fatty acid is at least one of the group consisting of lauric acid, palmitic acid and stearic acid. The composition of claim 1, wherein said unsaturated fatty acid is at least one of the group consisting of oleic acid, linoleic acid, linolenic acid, and erucic acid. The composition of claim 1 wherein the substituted fatty acid is 12-hydroxy stearic acid. According to claim 3, wherein the biodegradable polymer is at least one of the group consisting of starch, starch derivatives, lignocellulosic, cellulose, cellulose derivatives, wood fiber, chitosan, soy protein, casein, casein salt, gelatin Composition. 4. The method of claim 3 wherein the biodegradable polymer is, A, B, D, E is C _{2 ~ 20} alkylene group, G is a C _{6 ~ 21} when an arylene or alkylaryl renil, HO-A-OH and HOOC-B Aliphatic polyester produced by condensation polymerization of -COOH, aliphatic polyester produced by ring-opening polymerization of 2 to 20 carbon atoms, aliphatic polyester produced by self-condensation polymerization of HOOC-D-OH, or HO-E- An aliphatic / aromatic polyester produced by the condensation polymerization of OH and HOOC-G-COOH. 3 to 50 parts by weight of the additive composition of any one of claims 1 to 13 and 50 to 97 weight of at least one of the group consisting of polyethylene, polypropylene, polystyrene, polyethylene propylene, polyethylene styrene, polypropylene styrene, polyethylene propylene styrene Part containing a polymer composition.