KR20000033445A - Process for preparing aliphatic polyester-grafted polysaccharides and biodegradable polymer containing the same - Google Patents

Abstract

PURPOSE: A process for producing aliphatic polyester-grafted polysaccharides and biodegradable polymer containing the same are provided which manufacture in high yield and economically. CONSTITUTION: A preparation method of aliphatic polyester-grafted polysaccharides comprises the steps of mixing 1-95% by weight of a mixture of a polymerizable cyclic ester monomer containing 4-24 carbons and a polysaccharide plasticizer in a weight ratio of 1: 50 to 10: 1 at 50-120°C, reacting the mixture solution with 0.001-4 % by weight of a catalyst at 70-150°C and separating only aliphatic polyester-grafted polysaccharides form the obtained reactant. A biodegradable polymer containing aliphatic polyester-grafted polysaccharides, aliphatic polyester and polysaccharides is excellent in tensile strength, tensile modulus and elongation at break.

Description

Method for preparing aliphatic polyester-grafted polysaccharides and biodegradable polymers including electric polysaccharides

The present invention relates to a process for producing aliphatic polyester-grafted polysaccharides and to biodegradable polymers comprising the above polysaccharides. More specifically, the present invention provides aliphatic polyester-grafts in high yield by adding a mixture of a polymerizable cyclic ester monomer having 4 to 24 carbon atoms and a polysaccharide plasticizer to the polysaccharide at a predetermined ratio and adding a catalyst to react at a specific temperature. A method for preparing polysaccharides, and a biodegradable polymer comprising aliphatic polyester-grafted polysaccharides, aliphatic polyesters and polysaccharides prepared in the past.

The development of civilization has spurred the development of new synthetic materials that replace natural materials. As a result, in recent years, organic polymers have emerged. Organic polymers have rapidly increased in demand due to their unique physical properties, low price, ease of manufacture and processing, and semi-permanent lifespan, and contributed to the development of modern industrial technology.

However, due to the development of industrial and consumer cultures, environmental pollution caused by plastic wastes is increasing, and the disposal of plastic wastes has emerged as a big social problem. Therefore, the global demand for degradable polymers that can eliminate or minimize environmental pollution by collapsing or decomposing and returning to the natural circulation after use all over the world is rapidly increasing. Shows the movement of regulations on plastics that do not decompose.

Therefore, the development of a plastic material that eliminates environmental pollution by completely decomposing after use and returning to the natural circulation, has been studied by various researchers until now. In this example, biodegradable polymers were prepared using starch, which is a natural polymer, but starch is more fragile than synthetic polymers having different melt processing properties or mechanical properties. Also, starch-containing polymer resin compositions Its disadvantages include water absorption, starch decomposition at temperatures lower than the melting temperature, and poor mechanical properties.

Therefore, studies have been conducted to physically or chemically modify starch to solve the above problems. First, as a physical modification method, a method of imparting lipophilic properties by coating starch with a material such as silane, or a method of plasticizing starch using a plasticizer to improve melt processing characteristics, etc. Although this has been studied, it is still not preferable because it has a low yield of modified starch, and mechanical properties such as tensile strength and elongation of polymer resin compositions containing the modified starch are weak. In addition, the chemical modification method is to acetylate the hydroxyl group in order to reduce the hydrophilicity of the starch, or graft vinyl monomers (eg, methyl acrylate, styrene, methyl methacrylate, etc.) that does not decompose Or a method of grafting aliphatic polyester has been reported.

Among them, US Pat. Nos. 5,540,929, 5,616,671 and 5,578,691 disclose methods for grafting polycaprolactone to starch. Hydroxy group of starch using a Lewis acid catalyst, such as stannous octoate, or a metal alkoxide catalyst, such as aluminum isopropoxide. A polymer obtained by grafting a caprolactone monomer having a cyclic ester structure to a bulk polymerization method was prepared by grafting polycaprolactone into starch. However, when the graft polymer is prepared in this manner, polycaprolactone homopolymers are produced through side reactions so as to account for 42 to 50% by weight of the total product, so that the yield of the target graft polymer is increased. When initially supplied, the composition (the total weight of the starch and the caprolactone monomer) is about 50 to 58% by weight, and there is a problem that the production cost of modified starch is high.

Accordingly, the present inventors have made diligent efforts to solve the uneconomical problems caused by low yields in the manufacture of the graft polymers as described above. The aliphatic polyester-grafted polysaccharides having a molecular weight of 200 to 600 and a graft ratio of 10 to 30 mol% by grafting can be produced in high yield, and the aliphatic polyester-grafted thus prepared The biodegradable polymers including polysaccharides, aliphatic polyesters and polysaccharides have been found to have excellent physical properties such as tensile strength, tensile rate and elongation, and have completed the present invention.

After all, it is an object of the present invention to provide a method for producing aliphatic polyester-grafted polysaccharides in high yield by adding a mixture of a cyclic ester monomer and a polysaccharide plasticizer to a polysaccharide at a predetermined ratio and reacting at a specific temperature.

Another object of the present invention is to provide a biodegradable polymer containing aliphatic polyester-grafted polysaccharides, aliphatic polyesters and polysaccharides prepared in a proportion.

Hereinafter, a method of preparing the aliphatic polyester-grafted polysaccharide of the present invention will be described in more detail by process.

The weight percentages below are based on total reactant content or total biodegradable polymer content.

Step 1: mixing raw materials

1 to 95% by weight of polysaccharide is added to the reactor, and 5 to 95% by weight of a mixture of a 4- to 24 polymerizable cyclic ester monomer and a polysaccharide plasticizer is added, more preferably 50 to 120 ° C., more preferably 70 to 100 ° C. nitrogen Mix well for at least 0.5 hours in atmosphere. In this case, the mixture of the cyclic ester monomer and the polysaccharide plasticizer is a mixture of the electrical monomer and the plasticizer in a weight ratio of 1:50 to 10: 1, respectively.

In the above, the polysaccharide is a polysaccharide in which the α-D-glucopyranosyl unit is linearly or branched, and more preferably amylose, amylopectin, starch or starch. One or two or more combinations of amylose esters and the like are used, most preferably starch. Starch is a starch obtained from various raw materials such as rice, corn, potatoes, tapioca, wheat, oats, etc., and is in granular form, plasticized form, gelatinized form, physical or chemically modified form, Or mixtures of one or more of these.

The cyclic ester monomers may be substituted or unsubstituted lactones such as ε-caprolactone, δ-valerolactone, β-propiolactone, β-butyrolactone ) Or one or more of β-valerolactone, substituted or unsubstituted lactide, substituted or unsubstituted glycolide, or substituted or unsubstituted cyclic anhydride Use a combination.

In addition, the polysaccharide plasticizer uses one or two or more combinations of water, glycerin, polyglycerine, ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, sorbitol, sorbitol acetate, glucose or starch having a molecular weight of 500 to 10,000. .

Second Step: Graft Reaction Process

0.001 to 4% by weight of a catalyst is added to the mixed solution sufficiently mixed in the first step, and reacted in a nitrogen atmosphere at 70 to 150 ° C. so that the aliphatic polyester is grafted to the hydroxyl group of the polysaccharide and a reactant is obtained. .

In the above, the catalyst is a Lewis acid catalyst selected from titanium salts, zinc salts or tin salts, most preferably tin octoate (stannous 2-ethyl hexanoate), or aluminum isopropoxide (aluminum isopropoxide). ), Metal alkoxide such as titanium tetrabutoxide or aluminum tri- (sec butoxide), or metal alkyl do.

Third Step: Separation of Aliphatic Polyester-grafted Polysaccharides

Only aliphatic polyester-grafted polysaccharides are obtained from the reaction product obtained in the second step. Preferably, by adding toluene to the reactants, aliphatic polyester homopolymers dissolved in toluene, unreacted monomers, and aliphatic polyester-grafted polysaccharides not dissolved in toluene can be separated.

According to the method of the present invention described above, aliphatic polyester-grafted polysaccharides having a molecular weight of 200 to 600 and a graft ratio of 10 to 30 mol% of the grafted aliphatic polyester can be produced in a high yield of 59% by weight or more. In this case, the graft rate represents the mole number of the grafted aliphatic polyester per 100 anhydride glucose in%.

On the other hand, the present invention provides a biodegradable polymer comprising the aliphatic polyester-grafted polysaccharide. 5 to 40% by weight of electroaliphatic polyester-grafted polysaccharides, 20 to 50% by weight of aliphatic polyesters having 4 to 24 carbon atoms in repeating units, and 10 to 10 polysaccharides in which α-D-glucopyranosyl units are linearly or branched. Biodegradable polymer composed of 75% by weight has excellent mechanical properties such as excellent tensile strength, tensile and elongation. In this case, the polysaccharide may be used in granular form, plasticized form, gelatinized form, physically or chemically modified form, or a mixture of one or more thereof.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention in more detail, and it will be apparent to those skilled in the art that the scope of the present invention is not limited to these examples according to the gist of the present invention.

Examples 1-11: Preparation of Polycaprolactone-grafted Starch

In order to prepare polycaprolactone-grafted starch, first, a mixture of starch, caprolactone monomer and water was added to the content shown in Table 1 below, and mixed for 1 hour in a nitrogen atmosphere at 80 ° C. Then, graft reaction was carried out in a nitrogen atmosphere at 100 ° C. or 150 ° C. by addition of the catalyst of the ingredients and contents disclosed in Table 1 as well. The reactants obtained in this manner were separated using toluene into polycaprolactone homopolymers, unreacted monomers, and polycaprolactone-grafted starch, insoluble materials. The yield of polycaprolactone-grafted starch is summarized in Table 1 below.

Preparation of Polycaprolactone-Graft Starch division Starch / CL ^* / water (g / g / g) catalyst Catalyst content (% by weight) Temperature (℃) PCL ^** -graft starch (g) yield(%) Example One 30/30/30 Sn (Oct) ₂ 0.2 100 36.3 60.5 2 30/30/70 0.2 100 54.9 91.5 3 30/15/70 0.2 150 43.7 97.1 4 30/30/30 0.4 100 40.5 67.5 5 30/45/70 0.4 150 58.5 78.0 6 30/30/30 Al (OiPr) ₃ 0.04 100 35.6 59.3 7 30/30/70 0.04 100 40.2 67.0 8 30/15/70 0.2 150 35.6 79.1 9 30/30/30 Ti (OnBu) ₄ 0.6 100 38.8 64.7 10 30/30/70 0.6 100 42.6 71.0 11 30/15/70 1.2 150 36.0 80.0 *: Caprolactone **: polycaprolactone

As shown in Table 1, the aliphatic polycaprolactone-grafted starch prepared in Examples 1 to 11 was prepared with a yield of at least 59% and a maximum of 97.1%.

Examples 12-20: Preparation of Biodegradable Polymers

In order to prepare a biodegradable polymer comprising a polycaprolactone-grafted starch prepared in the above embodiment, first, a starch having a content as described in Table 2 together with water, a plasticizer of starch, is mixed (Brabender PL2000 internal mixer). , Brabender, Germany) and sufficiently gelatinized at 100 ° C. Here, as shown in Table 2 below, polycaprolactone-grafted starch and polycaprolactone were added, followed by mixing at 80 rpm using an electric mixer to prepare a biodegradable polymer. Then, mechanical properties such as tensile strength, tensile modulus, and elongation at break are measured according to methods well known in the art, and the results are summarized in Table 2 below. Indicated. At this time, the yield of the aliphatic polycaprolactone-grafted starch prepared in Example 1 is higher than the modified starch prepared by the conventional bulk polymerization means that the molecular weight and graft ratio of the grafted aliphatic polyester is high, This can be easily inferred by increasing the commercialization effect and further improving the mechanical properties of biodegradable polymers including electromodified starch. Thus, as shown in Table 2, it was found that the biodegradable polymer including polycaprolactone-grafted starch prepared in the present invention exhibits excellent tensile strength, tensile modulus and elongation.

Mechanical Properties of Biodegradable Polymers division Starch / PCL ^* / PCL ^* -Graft Starch (g / g / g) PCL ^* -grafted starch Tensile Rate (MPa) Tensile Strength (MPa) % Elongation Example 12 60/40/30 Example 1 540.0 13.7 25.0 13 60/40/30 Example 2 550.0 13.2 23.0 14 60/40/30 Example 3 525.0 14.0 57.0 15 50/50/30 Example 6 570.0 14.3 40.5 16 50/50/30 Example 9 585.0 13.6 38.5 17 60/40/20 Example 1 545.0 12.1 20.0 18 50/50/20 Example 7 575.0 13.8 18.5 19 60/40/10 Example 2 530.0 12.3 15.0 20 50/50/10 Example 10 560.0 14.1 13.5 *: Polycaprolactone

As described and demonstrated in detail above, the present invention provides a method for preparing aliphatic polyester-grafted polysaccharides and biodegradable polymers comprising the above-mentioned polysaccharides. According to the method of the present invention, a high yield of aliphatic polyester-grafted polysaccharides can be economically produced. In addition, the biodegradable polymer including the aliphatic polyester-grafted polysaccharides, aliphatic polyesters and polysaccharides thus prepared has excellent mechanical properties such as tensile strength, tensile modulus and elongation.

Claims (7)

(Iii) 5 to 95 weight percent of a mixture of 1 to 95% by weight of polysaccharide with respect to the total reactant content, and a polymerizable cyclic ester monomer having 4 to 24 carbon atoms and a polysaccharide plasticizer in a weight ratio of 1:50 to 10: 1. % Addition and mixing at 50-120 degreeC; (Ii) adding 0.001 to 4% by weight of catalyst to the solution mixed in the above step and reacting at 70 to 150 ° C; And, (Iii) separating only aliphatic polyester-grafted polysaccharides from the reactants obtained in the electrical process. Method for producing aliphatic polyester-grafted polysaccharides. The method of claim 1, The polysaccharide is characterized in that the α-D-glucopyranosyl unit is connected in a linear or branched form Method for producing aliphatic polyester-grafted polysaccharides. The method of claim 1, The cyclic ester monomer is characterized in that at least one compound selected from the group consisting of substituted or unsubstituted lactone, lactide, glycolide and cyclic anhydride Method for producing aliphatic polyester-grafted polysaccharides. The method of claim 1, The polysaccharide plasticizer is at least one substance selected from the group consisting of water, glycerin, polyglycerol, ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, sorbitol, sorbitol acetate, glucose and starch with a molecular weight of 500 to 10,000. Characterized Method for producing aliphatic polyester-grafted polysaccharides. The method of claim 1, (Iii) The process is characterized by separating aliphatic polyester homopolymers, unreacted monomers, and aliphatic polyester-grafted polysaccharides not dissolved in toluene, by adding toluene to the reactants. Method for producing aliphatic polyester-grafted polysaccharides. 5 to 40% by weight of aliphatic polyester-grafted polysaccharides having a molecular weight of 200 to 600 and a graft rate of 10 to 30 mol% of the grafted aliphatic polyester prepared by the method of claim 1 in the total biodegradable polymer content, repeat A biodegradable polymer comprising 20 to 50% by weight of aliphatic polyester having 4 to 24 carbon atoms and 10 to 75% by weight of a polysaccharide in which α-D-glucopyranosyl units are linearly or branched. The method of claim 6, The polysaccharide is characterized in that it is in granular form, plasticized form, gelatinized form, physically or chemically modified form, or a mixture of one or more thereof. Biodegradable Polymers.