KR20040005194A - The method of forming the biodegradable aliphatic polyester composite resin which has superior processability - Google Patents

Abstract

PURPOSE: A biodegradable aliphatic polyester composite resin, its preparation method and a molded product prepared by using the resin are provided, to improve crystallization velocity of aliphatic polyester and to enhance mechanical properties. CONSTITUTION: The biodegradable aliphatic polyester composite resin is prepared from an aliphatic dicarboxylic acid and ethylene glycol as an aliphatic diol with 20-70 wt% of an inorganic material. Preferably the inorganic material is at least one selected from the group consisting of talc, calcium carbonate and barium sulfate. Preferably the aliphatic dicarboxylic acid is succinic acid or a mixture of succinic acid with 20 wt% or less of at least one acid selected from the group consisting of oxalic acid, adipic acid, dimethyl succinate, dimethyl adipate and their anhydrides.

Description

Method for producing biodegradable aliphatic polyester composite resin having excellent moldability {THE METHOD OF FORMING THE BIODEGRADABLE ALIPHATIC POLYESTER COMPOSITE RESIN WHICH HAS SUPERIOR PROCESSABILITY}

The present invention relates to a high molecular weight thermoplastic aliphatic polyester resin having a biodegradability and a method for producing the same, and more particularly, is not only decomposed by microorganisms in soil, but also widely used as aliphatic diols in conventional aliphatic polyesters. 100% of ethylene glycol, which is cheaper than 4-butanediol and is easy to store and use, is cheaper than conventional aliphatic polyester resins, and has excellent mechanical strength as well as excellent productivity and processability. It relates to an aliphatic polyester composite resin that can be processed into a molded article and a method for producing the same.

Synthetic polymers such as polyolefins and aromatic polyesters are used in large quantities as raw materials for plastic products that are essential in daily life, but since they do not decompose in the natural environment, they have been criticized by society for causing environmental problems due to increased consumption. Came to the end.

Therefore, there is a rapid increase in the social demand for polymer materials having a new function of biodegradable plastics that can replace synthetic plastics, which dramatically improves convenience and durability when used.

The fact that aliphatic polyesters are biodegradable is already known and described in Journal of Macromol. SCI-Chem., A-23 (3), 1986, p393 ~ 409] Currently applied to medical materials, agriculture, fishery materials, and packaging materials, and research on practical use in various fields such as textiles, molded products, films, foams, etc. Is going on.

Such aliphatic polyesters are generally obtained by condensation reaction of aliphatic dicarboxylic acids with diols, which have a structure of the following Chemical Formula 1, and are highly biodegradable.

These are named polyester resins of (2,2) structure, (2,4) structure, (4,2) structure and (4,4) structure according to x and y values.

Among them, biodegradable polyester resins using succinic acid as aliphatic dicarboxylic acid and 1,4-butanediol as aliphatic diol have been studied a lot and are in practical use. In addition, research has been conducted to add ethylene glycol, propylene glycol, trimethylene glycol, neopentyl glycol, 1,8-hexanediol, 1,10-decanediol and 1,4-cyclohexanedimethanol to 1,4-butanediol. Coming. However, even if other aliphatic diols are added, at least 50 mol% or more of 1,4-butanediol can be used for practical use. In addition to 1,4-butanediol, other aliphatic diols not only have low reactivity but also have a low melting temperature and a low crystallization rate. The workability is so poor that it cannot be actually applied to the product.

However, 1,4-butanediol has a freezing point of 16 ° C, which is inconvenient for storage and use, and is relatively expensive. On the other hand, the low cost and low freezing point is below 13 ℃, so it is easy to store and use. The polymer of (2,2) structure made of cheap ethylene glycol has a melting temperature of around 100 ℃ and has a wide range of application. Mechanical strength is excellent. Accordingly, researches on biodegradable aliphatic polyesters using ethylene glycol as a main raw material have been actively conducted.

However, aliphatic polyester using ethylene glycol is difficult to obtain high molecular weight due to poor reactivity, and requires a long reaction time. In addition, due to the structure and crystallinity of the main chain, the crystallization rate is slow, which makes it impossible to discharge in mass production, and when molding with conventional molding equipment, productivity is low due to the low crystallization rate, which causes problems in practical use. Its use is very limited due to poor physical properties such as strength.

In order to speed up the crystallization rate, research has been conducted to add an inorganic material. However, when the inorganic material is added, the reactivity is further lowered, thus making it impossible to increase the degree of polymerization. Therefore, the desired viscosity is not increased and the reaction time is very long. As it does not exceed 20% by weight, the effect is insufficient. Therefore, research has been conducted on blending inorganic and organic materials with an extruder rather than polymerizing by adding inorganic and organic materials during the reaction, and has already been filed in Korean Patent Laid-Open Publication No. 1994-0014634.

However, this method not only increases the production cost by increasing the production stage, but also does not solve the problem of discharging which is not possible when ethylene glycol is used. Do not exceed

It is an object of the present invention to react with dicarboxylic acid as an aliphatic diol as low cost and easy to store ethylene glycol instead of 1,4-butanediol, and to add an inorganic additive during the reaction, so that the productivity and processability are very excellent, and also the reaction It is to provide a high molecular weight aliphatic polyester composite resin having a sufficient melting point in terms of practicality and high biodegradability with excellent thermal stability and mechanical strength by polymerizing a high viscosity resin having a short polymerization time and a high polymerization degree.

In the present invention, in order to achieve this object, the main component is an aliphatic dicarboxylic acid and ethylene glycol, and when 20 to 70% by weight of any one or a mixture of inorganic materials such as talc, calcium carbonate, barium sulfate and the like are reacted. Provided is a high viscosity biodegradable aliphatic polyester composite resin composition excellent in productivity and processability by adding a fast crystallization rate, and a method for producing the same.

Referring to the biodegradable aliphatic polyester composite resin composition according to the present invention in detail.

As the aliphatic dicarboxylic acid used in the present invention, succinic acid is most preferred, and when two or more kinds of mixtures are used, one of the aliphatic dicarboxylic acids oxalic acid, succinic acid, adipic acid, dimethylsuccinate, dimethyl adipate, and anhydrides thereof Or two or more mixtures are selected and used in combination with succinic acid. At this time, other acids to be mixed should not exceed 20% by weight, and if it exceeds 20%, it will not be suitable for practical use because it adversely affects the melting point and physical properties.

In addition, the aliphatic glycol uses only ethylene glycol and uses one or a mixture of two or more of talc, calcium carbonate and barium sulfate as inorganic additives. At this time, the amount of the added inorganic material is 40 to 70% by weight relative to the weight of the resin. When the added amount of the inorganic material is less than 20% by weight, the crystallization rate is slow and the swelling phenomenon of the resin makes it impossible to discharge it under mass production. When the addition amount of is less than 40% by weight, discharging is possible, but since the crystallization rate is slow and the cooling time must be long during processing, the workability is difficult to be commercialized. In addition, when the addition amount of the inorganic material exceeds 70% by weight, it is difficult to increase the degree of polymerization due to poor reactivity, the dispersion degree of the additive is too low and the amount of the inorganic material is too large compared to the resin matrix, it is difficult to apply to the product.

Referring to the biodegradable aliphatic polyester composite resin production method according to the present invention in detail.

In the method for producing a composite resin according to the present invention, aliphatic dicarboxylic acid and ethylene glycol are main components, and 20 to 70% by weight of one or two or more of the inorganic additives is added to the weight of the resin, and the catalyst, stabilizer, and coloring Adding 0.2 to 0.95% by weight, 0.2 to 0.7% by weight, and 0.01 to 0.02% by weight of the resin, respectively, to the esterification or transesterification reaction and the reaction product polycondensation reaction catalyst to 0.35 to 1.0 By weight, by adding a 0.2 to 0.5% by weight of the stabilizer to the weight of the resin is composed of a two-step reaction to the polycondensation reaction.

In the esterification reaction or the transesterification reaction, the molar ratio of the aliphatic dicarboxylic acid and ethylene glycol is preferably 1: 1.1-1: 1.5, and the reaction temperature is preferably about 180 to 210 ° C. .

Catalysts, stabilizers and colorants are added at the beginning of the esterification or transesterification reaction, and dibutyltin oxide and tetrabutyl titanate are used alone or as mixed catalysts, respectively. Phenylphosphate and trimethylphosphate are used alone or as mixed stabilizers, respectively. In addition, cobalt acetate is used as the colorant.

The addition amount of the catalyst is 0.2 ~ 0.95% by weight relative to the total resin weight, the addition amount of the stabilizer and the colorant is 0.2 ~ 0.7% by weight, 0.01 ~ 0.02% by weight relative to the total resin weight, respectively. When the addition amount of the catalyst is less than 0.2% by weight, the reactivity is lowered, the transesterification reaction rate is lowered, and the degree of polymerization is lowered. And if it exceeds 0.95% by weight, the reaction rate is fast but the color becomes poor. In addition, when the addition amount of the stabilizer is less than 0.2% by weight, the reaction product during the transesterification reaction may be hydrolyzed, the color is poor. On the other hand, if it exceeds 0.7% by weight, the reaction rate is lowered.

In the initial stage of the polycondensation of the present invention, a catalyst for promoting the polycondensation reaction is added, and the catalyst is magnesium acetate, tetrapropyl titanate, zinc acetate, tetrabutyl titanate, dibutyl tin oxide, tetrapropyl titanate, calcium acetate It is possible to use any one or two or more mixed catalysts selected from tetraisopropyl titanate, and the addition amount thereof is appropriately 0.35 to 1.0% by weight relative to the weight of the resin. If the amount is less than 0.35% by weight, there is a limit to increase the molecular weight by losing activity as a catalyst at a certain time, and when the amount exceeds 1.0% by weight, the reaction rate increases but the color is lowered.

In addition, a stabilizer may be added in the polycondensation step, and as the stabilizer, any one or two or more mixed stabilizers selected from trimethyl phosphate, trimethyl phosphine, triphenyl phosphate, and phosphate may be used. About 0.5 weight% is preferable. At this time, when the amount of the stabilizer is less than 0.2% by weight, it does not function as a stabilizer, whereas when it exceeds 0.5% by weight, the reaction is delayed to lengthen the reaction time.

In the present invention, the polycondensation reaction temperature is preferably 240 to 260 ° C, and the polycondensation reaction time becomes longer when the polycondensation reaction temperature is less than 240 ° C, while pyrolysis occurs when the polycondensation reaction temperature is higher than 260 ° C. The polycondensation reaction time is different depending on the amount of the catalyst and the stabilizer, but preferably about 150 to 300 minutes.

The biodegradable aliphatic polyester composite resin produced by this method is not only excellent in productivity and processability compared to conventional aliphatic polyester, but also can be molded in existing molding machines and has properties similar to those of conventional polypropylene, a general-purpose resin. .

Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1

118 g of succinic acid, 83.79 g of ethylene glycol, 28.8 g of talc were added into a 500 ml condensation polymerization flask. 0.02 g of zero cobalt acetate is mixed and esterified at a temperature of 180 ° C. under a nitrogen atmosphere. When 80% of the theoretical amount of water flows out, the reaction temperature is raised to 200 ° C. and the esterification reaction proceeds until the remaining theoretical amount flows out.

After completion of the esterification reaction, 0.3 g of dibutyltin oxide, 0.1 g of antimony acetate, 0.25 g of tetrabutyl titanate, 0.2 g of triphenylphosphate and 0.2 g of trimethylphosphate as stabilizers are added to the reactor. Polycondensation reaction of the reaction mixture at 220 ℃ for 10 minutes, while gradually raising the vacuum temperature in the reactor while raising the reaction temperature to 250 ℃ to make a high vacuum of about 0.3torr.

In the reaction state, the polycondensation reaction was further performed for 180 minutes, and the number average molecular weight was 35,000, the weight average molecular weight was 105,000, and the melting point was 98 ° C.

Examples 2 to 6

The same procedure and conditions as in Example 1 were conducted except that the amount of the inorganic substance was changed as shown in Table 1 below.

Comparative Example 1

Aliphatic polyesters were prepared using the same aliphatic diols and dicarboxylic acids as in Example 1 without the addition of minerals. Tensile strength, workability, etc. of the prepared resin were tested and the results are shown in Table 1 below.

Discharge: A phenomenon that occurs when discharging on a mass production scale

Processability: Results of processing of disposable molded products (spoons, plates, forks, etc.) using existing general purpose resin injection machines

Compared to the 1,4-butanediol, an aliphatic diol commonly used in conventional biodegradable aliphatic polyesters, the aliphatic polyesters synthesized using ethylene glycol, which is relatively inexpensive and easy to store, have a low crystallization rate. Not only is it impossible to discharge, but the conventional general-purpose injector has a problem in that productivity is practically impossible due to poor productivity. Therefore, the present invention solves these problems by increasing the crystallization rate by adding an inorganic material during the reaction, as well as providing a biodegradable aliphatic polyester composite resin having excellent mechanical properties, and the price is lower than that of the existing biodegradable aliphatic polyester. By inventing aliphatic polyester which can replace polypropylene which is widely used in disposable injection products, it will be possible to reduce environmental pollution caused by plastic.

Claims (4)

A biodegradable aliphatic polyester composite resin characterized by adding 20 to 70% by weight of inorganic materials when synthesizing ethylene glycol as aliphatic dicarboxylic acid and aliphatic diol. [Claim 2] The biodegradable aliphatic polyester composite resin according to claim 1, wherein the inorganic filler is one or two or more selected from talc, calcium carbonate and barium sulfate. The aliphatic dicarboxylic acid according to claim 1, wherein succinic acid is used alone or when two kinds of mixtures are used, oxalic acid, succinic acid, adipic acid, dimethylsuccinate, dimethyl adipate and mixtures of one or two or more of anhydrides thereof. Biodegradable aliphatic polyester composite resin, characterized in that selected and used in combination with succinic acid, the other acids to be mixed does not exceed 20% by weight. A molded article formed by injection or extrusion molding the high molecular weight aliphatic polyester composite resin according to claim 1.