KR0121998B1 - Thermoplastic biodegrable resin and method for making thereof - Google Patents

Abstract

The mixture of dimethylsuccinate and dimethylglutalate as bi-funcitonal carboxylic acid component was mixed with the mixture of 1,4 butanediol and ethyleneglycol in a mol. ratio of 1:1.4-1:2 in presence of 0.005-2 wt. % tetra butyltitanate to give a half product which is polycondensed in presence of 0.3-1.5 wt. % dibutyltitanate at 240-270 deg.C for 240-350 min to give a final product.

Description

Thermoplastic Biodegradable Resin and Manufacturing Method Thereof

The present invention relates to a thermoplastic biodegradable resin composition and a method for producing the same, more specifically, the number average molecular weight is 25.000 ~ 45.000 intrinsic viscosity is 1.4 or more, the melt flow index (MI, Melt Index) is 0 ~ 10, melting point It relates to a thermoplastic biodegradable resin represented by the following general formula which is 90-120 degreeC, and its manufacturing method.

(Wherein R ₁ is 1,4-butanediol alone or a residue derived from a mixed monomer of 1,4 butanediol and ethylene glycol, R ₂ is a residue derived from a mixed monomer of dimethylsuccinate and dimethylglutarate, n is Integer from 130 to 250)

Looking at the recent social and environmental trends, environmental pollution is a serious social problem in the world. Especially, since the plastic used for various uses is a hardly decomposable substance, the natural environment is seriously affected by such plastic waste. It is being destroyed so that regulations are being implemented or introduced in countries around the world.

On the other hand, since aliphatic polyesters are generally biodegradable (Journal of Macromol. SCI-Chem., A23 (3), 1986, 393-409), they are currently applied to medical materials, agricultural materials and packaging materials, Practical research is in progress. However, existing aliphatic polyesters have low melting points, high melt flow indices, and poor physical properties such as heat resistance and mechanical strength due to problems in the structure and crystallinity of the main chain. (RD Evalulation Report No. 47 Chart 3).

Conventional methods for producing aliphatic polyesters include Japanese Patent Application Laid-Open No. 4-189822 and Japanese Patent Application Laid-Open No. 4-189823, which have low melting points and low molecular weights of less than 20.000. Since it is difficult to develop, a method of introducing isocyanate has been proposed, but this resin is also difficult to develop into a biodegradable resin, and it is not only harmful to the human body during operation, but also aliphatic without isocyanate after molding. Compared to polyester, ester bonds are more difficult to cut, resulting in poor biodegradability.

Therefore, the present inventors developed a biodegradable aliphatic polyester by directly condensation of ethylene glycol and 1,4-butanediol as a difunctional carboxylic acid component and succinic acid as a difunctional carboxylic acid component without using a method of increasing the molecular weight using isocyanates. (See Korean Patent Application No. 92-23688).

However, the biodegradable aliphatic polyester of the present inventors Korean Patent Application No. 92-23688 considerably solves the above-mentioned problems of the prior art, but it is still somewhat insufficient in physical properties.

Therefore, the present inventors have improved and improved the biodegradable aliphatic polyester having better physical properties. As a result, the improved physical properties when the bifunctional acid component is used as a mixture of dimethyl succinate and dimethyl glutarate It has been discovered that the new biodegradable aliphatic polyester resins can be provided.

Therefore, according to the present invention, a thermoplastic biodegradable resin represented by the following general formula having an intrinsic viscosity of 1.4 or more, a melting point of 90 to 120 ° C, and a molecular weight of 25,000 to 45,000 is provided.

(Wherein R ₁ is 1,4-butanediol alone or a residue derived from a mixed monomer of 1,4 butanediol and ethylene glycol, R ₂ is a residue derived from a mixed monomer of dimethylsuccinate and dimethylglutarate, n is Integer from 130 to 250)

Hereinafter, the present invention will be described in more detail.

Preparation of the thermoplastic biodegradable aliphatic resin (I) according to the present invention is a mixed monomer of dimethyl succinate and dimethyl glutarate as a bifunctional carboxylic acid component and a mixed monomer of 1,4-butanediol and ethylene glycol as a difunctional alcohol component. And transesterification with a molar ratio of 1 / 1.4 to 1/2. At this time, if the molar ratio is less than 1/14, the color is poor and the reactivity is lowered. If the molar ratio exceeds 1/2, the manufacturing cost is increased without improving the reactivity.

In the transesterification reaction, a catalyst is added at the beginning of the reaction, and the reaction temperature is preferably in the range of 150 to 230 ° C. The product obtained by adding a catalyst and a stabilizer at the end of the transesterification reaction or the beginning of the condensation polymerization was condensed. At this time, the condensation polymerization temperature is preferably 240 to 270 ° C. If the condensation polymerization temperature is less than 240 ° C., the reaction time becomes too long, and if the condensation polymerization temperature is higher than 270 ° C., there is a problem of thermal decomposition and poor color. In addition, the polycondensation time varies depending on the amount of catalyst and stabilizer, but is preferably between 240 and 350 minutes. At this time, the polymerization time can be adjusted to the extent necessary to increase the molecular weight as the molecular weight increases as the time increases.

The bifunctional carboxylic acid component used in the present invention is a mixture of dimethyl succinate and dimethyl glutarate, and the mixing ratio thereof is suitably 86: 14 to 98: 2 by weight. At this time, if the amount of dimethyl glutarate exceeds 14% by weight, the melting point and physical properties are lowered, and when the amount of dimethyl glutarate is less than 2% by weight, the flexural modulus increases, the flexibility decreases, the crystallinity increases, and the decomposition effect decreases. There is a problem in that film formation is poor due to a decrease in viscosity and melt flow index, and workability is lowered.

In the present invention, the difunctional alcohol component is 1,4-butanediol alone or a mixture of 1,4-butanediol and ethylene glycol, and the mixing ratio thereof is preferably 65:35 to 100: 0 by weight. At this time, the ratio affects the melting point of the resin, and when the content of ethylene glycol exceeds 35% by weight, the melting point is too low to be suitable.

In addition, as a catalyst to be added at the beginning of the transesterification reaction of the present invention, tetrabutyl titanate, calcium acetate mixture and single tetrabutyl tanate are used, and the addition amount is preferably 0.005 to 2% by weight. If less than 0.005% by weight is added, it is insufficient to let methanol out, and if it exceeds 2% by weight, the methanol outflow is too fast to accelerate the reaction, resulting in poor color.

In addition, as a catalyst used at the end of the transesterification reaction or during the condensation polymerization, dibutyltin oxide, tetrabutyl titanate, tetraisopropyl titanate, or the like may be used, or a mixture of two or more thereof may be used. % Is suitable. If less than 0.3% by weight, the intrinsic viscosity and molecular weight does not increase, the reaction rate is slow, and when used in excess of 1.5% by weight, the reaction is faster but the color becomes worse.

In this case, a stabilizer should be added in consideration of the color side of the resin. Examples of suitable stabilizers for use in the present invention include neopentyl-diaryl-oxytriphosphate, triphenylphosphine, trimethyl phosphate, and the like. Trimethyl phosphate is advantageous, and its amount is suitably 0.1 to 0.8% by weight. If the amount is less than 0.1% by weight, the effect is insufficient as a stabilizer, and when the amount exceeds 0.8% by weight, the reaction time becomes very long, and thus physical properties such as color may be deteriorated.

Since the thermoplastic biodegradable resin prepared according to the present invention is not only excellent in biodegradability but also excellent in general physical properties, it is possible to prevent environmental pollution and thus, resin materials in various industrial fields such as medical materials, agricultural and fishery materials, and packaging materials. Very useful as

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the examples. In addition, in the following Examples and Comparative Examples, biodegradability evaluation, intrinsic viscosity, molecular weight and melt flow properties were carried out in the following manner.

◇ Biodegradable… Conducted according to ASTM D-4300. First, a 100 micromolar phosphate buffer solution having a pH of 7.0 was used as the reaction solution, and 100 mg of a 40 μm-thick film made of aliphatic polyester was added to the solution, followed by Asperilius Niger. 0.2 mg was added to make the volume of the total reaction solution 1 l. Thereafter, the reaction solution was reacted with stirring at 150 rpm for 60 days at 37 ° C., and a sample was taken to evaluate biodegradability by molecular weight change.

◇ intrinsic viscosity. The temperature was measured at 30 ° C using orchlorochlorophenol, and the melting point was measured by differential scanning calorimetry (DSC) at a rate of temperature increase of 10 ° C per minute.

◇ Number average molecular weight. It was measured by gel chromatography (GPC) as a mixed solvent of orthochlorophenol and chloroform.

◇ Number average molecular weight reduction rate. Obtained by the following formula.

◇ Melt flow index. It is measured under the conditions of 120 degreeC and 2160 g.

Example 1

Monomer 73.6g, 90.1g 1,4-butanediol, 14.7g ethylene glycol, 0.03g tetrabutyl titanate and calcium acetate The mixture is mixed with 0.001 g and the temperature is raised to 210 ° C. until the methanol is released.

After the completion of the transesterification reaction, 0.03 g of tetrabutyl titanate, 0.45 g of dibutyl tin oxide, and 0.2 g of trimethyl phosphate as a stabilizer were added by slurry to ethylene glycol or 1,4-butanediol, and then the mixture was added at 230 ° C. After mixing well for 10 minutes, the temperature was gradually raised to 250 ° C. while the pressure was 0.3 mmHg, followed by condensation polymerization, followed by discharging to obtain aliphatic polyester.

[Examples 2 to 5]

The amount of each component was changed as shown in Table 1, and in Examples 2, 3, and 5, except that only tetrabutyl titanate was added without using calcium acetate as a catalyst in the initial stage of the ester reaction. The same procedure was repeated.

Comparative Example 1

The amount of each component was changed as shown in Table 1, and the same procedure as in Example 1 was repeated except that only tetrabutyl titanate was added without using calcium acetate as a catalyst in the initial stage of the ester reaction.

Comparative Example 2

118 g of succinic acid and 85 g of ethylene glycol are mixed in a nitrogen gas stream in a hot melt condensation reaction tube, and the temperature is raised to 210 ° C. until the water of theoretical value flows out. After that, when the water completely flows out, 0.5 g of tetrabutyl titanate is slurried in ethylene glycol and introduced under a nitrogen stream. After mixing the mixture well at 200 ° C. for about 10 minutes, the condensation reaction proceeds by reducing the pressure to 0.3 mmHg while gradually raising the temperature to 220 ° C. Then, the reaction was carried out for 5 hours and then discharged to obtain an aliphatic polyester.

Comparative Example 3

118 g of succinic acid and 127.5 g of 1,4-butanediol are mixed in a heated melt condensation reaction tube under a nitrogen stream, and the temperature is raised to 210 ° C. until the water of theoretical value flows out. After that, when water is completely discharged, 0.5 g of tetrabutyl titanate is poured into a 1,4-butanediol slurry under nitrogen stream. After mixing the mixture well at 200 ° C. for about 10 minutes, the condensation reaction proceeds by reducing the pressure to 0.3 mmHg while gradually raising the temperature to 220 ° C. Then, the reaction was carried out for 5 hours, hexamethylene isocyanate 2g (OH / NCO 1 / 0.8) was added at 190 ℃ reacted for 10 minutes and then discharged to obtain an aliphatic polyester.

Comparative Example 4

Remarks Example 3 was carried out in the same manner as in Example 3, but after the reaction for 5 hours, 5 g (OH / NCO 1 / 0.85) of petol methane diisocyanate was added at 190 ° C without being discharged, and then reacted for 10 minutes and then discharged.

The addition amount, reaction time, and physical properties of each component of the Examples and Comparative Examples are shown in Table 1 below.

As can be seen from the table, according to the present invention, the molecular weight and melting point, the melt flow index and the intrinsic viscosity have good results. Particularly, Comparative Example 2 was unable to form a low molecular weight film, and thus the molecular weight reduction rate could not be measured. Blowing injection is only possible when the melt flow index is less than 7.

Claims (7)

It is prepared by condensation polymerization of difunctional carboxylic acid component, which is a difunctional alcohol component selected from 1,4-butanediol alone or a mixture of 1,4-butanediol and ethylene glycol, and a mixture of dimethylsuccinate and dimethylglutarate. Is 1.4 or more, the melting point is 90 ~ 120 ℃, molecular weight 25.000 to 45.000 thermoplastic biodegradable resin represented by the following general formula: Wherein R ₁ is a residue derived from 1,4-butanediol alone or a mixed monomer of 1,4 butanediol and ethylene glycol, R ₂ is a residue derived from a mixed monomer of dimethylsuccinate and dimethylglutarate, n is 130 Integer from to 250. In the method of manufacturing a thermoplastic biodegradable resin represented by the following general formula having an intrinsic viscosity of 1.4 or more, a melting point of 90 to 120 ° C and a molecular weight of 25,000 to 45,000, Wherein R ₁ is a residue derived from 1,4-butanediol alone or a mixed monomer of 1,4 butanediol and ethylene glycol, R ₂ is a residue derived from a mixed monomer of dimethylsuccinate and dimethylglutarate, n is 130 Integer from to 250. A mixture of dimethylsuccinate and dimethylglutarate is used as the difunctional carboxylic acid component, 1,4-butanediol alone or a mixture of 1,4-butanediol and ethylene glycol is used as the difunctional alcohol component, and the catalyst is an ester. 0.005 to 2% by weight at the beginning of the exchange reaction, 0. to 1.5% by weight at the end of the transesterification or condensation polymerization, 0.1 to 0.8% by weight stabilizer is a method for producing a thermoplastic biodegradable resin. The method of claim 2, wherein the bifunctional carboxylic acid is a method for producing a thermoplastic biodegradable resin, characterized in that dimethyl succinate and dimethyl glutarate are mixed in a weight ratio of 86: 14 ~ 98: 2. The method for preparing a thermoplastic biodegradable resin according to claim 2, wherein the catalyst used at the beginning of the transesterification reaction is tetrabutyltita alone or a mixture of tetrabutyltitanate and calcium acetate. [Claim 3] The thermoplastic biodegradable resin of claim 2, wherein the catalyst used at the end of the transesterification reaction or the polycondensation polymerization is at least one selected from dibutyl tin oxide, tetrabutyl titanate, and tetraisopropyl titanate. Manufacturing method. The method of claim 2, wherein the stabilizer is trimethyl phosphate. The method for producing a thermoplastic biodegradable resin according to claim 2, wherein the polycondensation temperature is 240 to 270 ° C.