JP2004124085A - Method for producing aliphatic polyester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing in a short time an aliphatic polyester having practically sufficient strength, or a method for producing in a good polymerization efficiency and conveniently the aliphatic polyester having a target molecular weight in the presence of a small quantity of a catalyst. <P>SOLUTION: The method for producing the aliphatic polyester comprises esterifying an aliphatic diol with an aliphatic dicarboxylic acid or a derivative thereof, subsequently polymerizing the esterified matter in the presence of a polymerization catalyst to obtain the aliphatic polyester, wherein the polymerization catalyst is added in the esterification reaction process after the conversion of the esterifying reaction reaches 80%. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a method for producing an aliphatic polyester, in which an aliphatic polyester having practically sufficient strength can be produced in a short time, or an aliphatic polyester having a target molecular weight can be efficiently produced with a small amount of catalyst. It relates to a method that can be manufactured.

Conventionally, as an aliphatic polyester, a method of polycondensing a dibasic aliphatic carboxylic acid such as oxalic acid, succinic acid or adipic acid with an aliphatic glycol such as ethylene glycol or 1,4-butanediol, or a cyclic lactone It is known that they can be obtained by ring-opening polymerization of the compounds.

Such an aliphatic polyester is different from an aromatic polyester in that (1) its melting point is relatively low, and (2) it is difficult to increase its molecular weight. Has disadvantages, and various methods have been proposed to solve them.

For example, the glycol component and the aliphatic dicarboxylic acid component are esterified, and the produced polyester diol is subjected to a deglycol-reaction in the presence of a catalyst at a temperature of 180 to 230 ° C and a high vacuum of 0.005 to 0.1 mmHg. By doing so, a high molecular weight aliphatic polyester having a number average molecular weight of 25,000 to 70,000 and substantially having a hydroxyl group in a terminal group has been proposed (for example, see Patent Document 1).

However, performing the reaction in such a high vacuum state is complicated in industrial control, and the equipment is special and expensive.

On the other hand, there has been proposed a method for producing an aliphatic polyester in which a catalyst is added to a reaction system at least twice at intervals of at least 10 minutes (for example, see Patent Document 2).
JP-A-5-310898 JP-A-8-92361

The present invention can produce an aliphatic polyester having practically sufficient strength in a short period of time, or a high molecular weight aliphatic polyester having a target molecular weight with a small amount of catalyst, as compared with a conventionally known method, and It is to provide a method that can be easily manufactured.

The gist of the present invention is that, in a method for producing an aliphatic polyester, an aliphatic diol and an aliphatic dicarboxylic acid or a derivative thereof are subjected to an esterification reaction, and then the resultant is subsequently polymerized in the presence of a polymerization catalyst to thereby prepare a fatty acid polyester. The present invention relates to a method for producing an aliphatic polyester, wherein a polymerization catalyst is added to an esterification reaction step in which the esterification reaction rate in the esterification reaction is 80% or less when producing the polyester.

According to the production method of the present invention, a high molecular weight aliphatic polyester can be obtained in a short time. In addition, since the polymerization efficiency is improved, it is possible to reduce the amount of catalyst added when obtaining an aliphatic polyester having a target molecular weight, and the resulting aliphatic polyester has less heat generation and less foreign matter generation and coloring. An improved product is obtained.

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

The aliphatic polyester of the present invention comprises, as a main component, a polycondensate and a copolycondensate of an aliphatic diol and an aliphatic dicarboxylic acid or a derivative thereof, and an aliphatic diol and an aliphatic dicarboxylic acid or a derivative thereof and a hydroxycarboxylic acid. Copolycondensates and the like.

Here, the aliphatic diol includes an alicyclic diol, and specific examples of the aliphatic or alicyclic diol include ethylene glycol, 1,2-propanediol, and 1,3-propanediol. 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,4-cyclohexanediol, Suitable examples include 1,4-cyclohexanedimethanol, neopentyl glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol. Of these, ethylene glycol, 1,4-butanediol, 1,3-propanediol, and 1,4-cyclohexanedimethanol are particularly preferred. These can be used alone or as a mixture of two or more.

の 他 In addition to these, monofunctional or trihydric or higher alcohols can be used in combination as long as polymerization is not hindered.

The aliphatic dicarboxylic acid or a derivative thereof includes an alicyclic dicarboxylic acid, and includes, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacine. Acid, undecadicarboxylic acid, dodecadicarboxylic acid, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, and alkyl esters having about 1 to 4 carbon atoms of these dicarboxylic acids, derivatives such as anhydrides, Each is listed.

内 Of these, succinic acid, adipic acid, sebacic acid, anhydrides and lower alkyl esters thereof are preferable, and succinic acid, succinic anhydride, or a mixture thereof is particularly preferable. These can be used alone or in combination of two or more. Further, a monofunctional or trivalent or higher carboxylic acid or a derivative thereof may be used in combination as long as the polymerization is not hindered.

Furthermore, examples of the hydroxycarboxylic acid include glycolic acid, lactic acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3-methyl-n-butyric acid, 2-hydroxy-3,3-dimethyl-n-butyric acid, -Hydroxy-n-butyric acid, 4-hydroxy-n-butyric acid, 2-hydroxy-n-valeric acid, 3-hydroxy-n-valeric acid, 4-hydroxy-n-valeric acid, 5-hydroxy-n-valeric acid , 2-hydroxy-n-hexanoic acid, 2-hydroxy-i-hexanoic acid, 3-hydroxy-n-hexanoic acid, 4-hydroxy-n-hexanoic acid, 5-hydroxy-n-hexanoic acid, 6-hydroxy- Examples include n-hexanoic acid and malic acid. In addition, an organic acid having a pKa of 3.7 or less, such as malic acid, citric acid, and tartaric acid, can be used to further improve the polymerization efficiency.

When these optical isomers are present, they may be any of the D-form, L-form, and racemic form, and may be in the form of solid, liquid, or aqueous solution. Among these, lactic acid or glycolic acid is preferred, and the form is preferably a 30-95% aqueous solution because it can be easily obtained. These hydroxycarboxylic acids can be used alone or as a mixture of two or more.

The amount of the aliphatic or alicyclic diol used is substantially equimolar to the aliphatic dicarboxylic acid or derivative thereof, but is generally used in consideration of the amount distilled out during the polymerization reaction. The actual amount used need not necessarily be equimolar. Usually, it is used in an amount of 0.5 mol to 2 mol, preferably 0.8 mol to 1.5 mol, per 1 mol of dicarboxylic acid or a derivative thereof.

Further, in addition to the above-mentioned raw materials, other copolymer components can be introduced. Examples of other copolymerization components include aromatic oxycarboxylic acids such as hydroxybenzoic acid, aromatic diols such as bisphenol A, and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. The copolymerization component having an aromatic ring can be copolymerized in a range of 50 mol% or less, preferably 30 mol% or less of all diols and all dicarboxylic acids constituting the aliphatic polyester.

The production method of the present invention is a melt polymerization method used in the production of a general polyester, generally, after undergoing an esterification step of an aliphatic dicarboxylic acid or a derivative thereof and an aliphatic diol as raw materials, This is a polymerization method in which the polymerization step is carried out in a state where the reaction mixture is melted to increase the molecular weight.

The esterification step is usually performed at a temperature in the range of 50 ° C to 300 ° C, preferably 120 ° C to 260 ° C, and is generally performed at normal pressure. If the reaction temperature is too low, the reaction does not proceed efficiently, and if the temperature is too high, the decomposition reaction tends to be significant.

カ ル ボ ン During this step, the carboxylic acid or its derivative and the alcohol react to form an ester bond. With the progress of the reaction, water is mainly generated in the case of direct esterification of carboxylic acid and alcohol, and in the case of transesterification, the exchanged alcohol is generated, so that they are reacted while distilling them out of the system. . The progress of the reaction can be monitored by the amount of such distillate distilled off or the terminal group concentration of the reaction product.

At this time, a catalyst may or may not be added to promote esterification. The esterification time is usually 20 minutes to 5 hours, preferably 30 minutes to 3 hours.

The polymerization catalyst is added in the esterification reaction step having an esterification reaction rate of 80% or more. The preferred point of addition is at least 90%, more preferably at least 93%, the esterification reaction rate. Here, the esterification rate is calculated from the acid value of the esterification reaction product, and the acid value can be obtained by measuring by an potentiometric titration method with an aqueous sodium hydroxide solution. By adding the catalyst when the amount of the distillate generated in the esterification step is reduced, the subsequent polymerization efficiency can be improved. After the addition of the catalyst, the esterification reaction is further advanced or the process proceeds to the next polymerization step.

重合 As the polymerization catalyst used in the present invention, a conventionally known polyester polymerization catalyst can be used. Specific examples of the polymerization catalyst include compounds containing Ge, Ti, Sb, Mg, Hf, Zn, Zr, Co, Ni, Sn, Si, P, and Fe.

Specific examples of these include germanium dioxide, antimony trioxide, magnesium oxide, zinc oxide, tin oxide, iron oxide, and other metal oxides, titanium tetrabutoxide, germanium tetrabutoxide, germanium tetraethoxide, zirconium tetraethoxy. Metal alkoxides such as zirconium, tetraethoxysilane, zirconium tetraisopropoxide, zirconium tetrabutoxide, hafnium tetrabutoxide, hafnium tetraisopropoxide, zirconium acetylacetonate, hafnium acetylacetonate, nickel acetylacetonate, tin acetylacetonate , Acetylacetonates such as zinc acetylacetonate, chlorides such as zinc chloride, tin chloride, zirconium chloride, magnesium acetate Arm, zinc acetate, cobalt acetate, nickel acetate, zinc benzoate, zinc oxalate, carboxylates such as tin oxalate, hafnium THF complex, dibutyltin oxide, and the like zinc phosphate.

Further, protic acids such as sulfuric acid, sulfonic acid, hydrochloric acid, and methanesulfonic acid are also included.
Among these, compounds containing Ge, Ti, Sb, Mg, Hf and Zn are particularly preferred. These can be used alone or in combination of two or more. The form at the time of addition is not particularly limited, but the catalyst compound may be added as it is or may be added in an appropriate solution state (aqueous solution, alcohol (glycol) solution, coexistence with acid) or the like. The amount of the catalyst to be used is 0.001 to 3% by weight, more preferably 0.005 to 1.5% by weight, based on the amount of the monomer used.

重合 The polymerization step following the esterification step is usually performed at a temperature in the range of 100 ° C. to 350 ° C., preferably 150 ° C. to 300 ° C. In order to carry out the polymerization efficiently, the reaction is generally allowed to proceed under reduced pressure. Usually, the degree of reduced pressure in the system is gradually increased, and finally the reaction is performed under reduced pressure of 1.3 kPa to 1 Pa. The higher the degree of reduced pressure is, the more advantageous in promoting the polymerization, but the polymerization is usually performed in the range of 0.7 kPa to 10 Pa from the viewpoint of substantial equipment compatibility. The polymerization time is adjusted according to the desired molecular weight, but is usually in the range of 1 hour to 15 hours, preferably 1 hour to 6 hours.

The polymerization reaction usually proceeds by distilling off the water or glycol present or generated in the reaction system, but depending on conditions such as reducing the amount of the glycol component charged, an acid component, or an anhydride thereof, The polymerization reaction can be advanced by distilling off the oligomer component and the like.

Further, the number average molecular weight in terms of GPC polystyrene of the aliphatic polyester obtained by the production method of the present invention is preferably 10,000 to 300,000, more preferably 20,000 or more, still more preferably 30,000 or more, and the upper limit is 200,000 or less is preferable.

According to the production method of the present invention, an aliphatic polyester having a high molecular weight is efficiently obtained, and has a sufficient strength for practical use; therefore, a film is formed by a general-purpose plastic molding method such as an injection molding method, a hollow molding method and an extrusion molding method. Available for molded products such as laminated films, sheets, boards, stretched sheets, monofilaments, multifilaments, non-woven fabrics, flat yarns, staples, crimped fibers, tapes with splits, split yarns, composite fibers, blow bottles, foams, etc. is there. At that time, a nucleating agent, an antioxidant, a lubricant, a coloring agent, a release agent, a filler, another polymer, and the like can be added as necessary.

Further, according to the production method of the present invention, since the polymerization efficiency during the production of the aliphatic polyester is improved, it is possible to reduce the amount of the added catalyst, the generation of foreign matters, less coloring, and improved thermal stability. An aliphatic polyester can be obtained.

脂肪 Also, since the aliphatic polyester obtained by the production method of the present invention has biodegradability, it is completely decomposed by enzymes, bacteria in soil and the like, and is a very useful resin in environmental hygiene. Therefore, shopping bags, garbage bags, horticultural materials, agricultural films, food containers, food packaging materials, cosmetic containers, detergent containers, bleach containers, fishing lines, fishing nets, ropes, binding materials, surgical threads, hygienic cover stock materials, It can be used for applications such as cool boxes, cushioning materials, and synthetic paper.

Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist. The physical properties in the following examples were measured by the following methods.

(1) Esterification reaction rate: Calculated from the acid value of the esterification reaction product. The acid value was measured by potentiometric titration with an aqueous sodium hydroxide solution.

(2) Number average molecular weight (Mn): measured by GPC method. The sample was dissolved in chloroform, and measured in terms of polystyrene using GPC HLC-8020 manufactured by Tosoh Corporation. The column used was PLgel-10μ-MIX.

Example 1
100.2 g of succinic acid and 88.7 g of 1,4-butanediol were charged into a 250-mL reactor equipped with a stirrer, a nitrogen inlet tube, a heating device, and a reagent addition port. While stirring the contents of the container, nitrogen gas was introduced, the temperature was raised to 210 ° C. in a nitrogen gas atmosphere, and the reaction was carried out at this temperature for 90 minutes. When the esterification reaction rate at this time was measured, it was 93%. At this time, 5.4 g of a 90% aqueous lactic acid solution in which 1% by weight of germanium oxide was previously dissolved was added to the system, the reaction temperature was raised to 230 ° C., and the system was gradually reduced in pressure to 67 Pa over 90 minutes. Further, polymerization was carried out for 2 hours while maintaining the degree of reduced pressure. After the completion of the reaction, the molten polymer was drawn out from the reactor into a thread and cut into granules to obtain aliphatic polyester pellets. The obtained aliphatic polyester had a number average molecular weight in terms of polystyrene of 22,000 by the GPC method.

Example 2
In Example 1, 0.11 g of tetrabutoxytitanium was added instead of the lactic acid solution of germanium oxide as the polymerization catalyst, the reaction temperature was raised to 230 ° C., and the system was gradually reduced in pressure to 67 Pa over 90 minutes. The reaction was carried out in the same manner as in Example 1 except that polymerization was carried out for 3 hours while maintaining the degree of reduced pressure, to obtain aliphatic polyester pellets. The obtained aliphatic polyester had a number average molecular weight in terms of polystyrene of 21,000 by the GPC method.

Example 3
In Example 1, the polymerization catalyst was replaced with 5.4 g of a 90% aqueous lactic acid solution containing 0.5% by weight of germanium dioxide and 0.06 g of tetrabutoxytitanium in which 0.5% by weight of germanium dioxide was dissolved when the esterification reaction rate was 95%. Was reacted in the same manner as in Example 1 to obtain an aliphatic polyester pellet. The obtained aliphatic polyester had a number average molecular weight in terms of polystyrene of 23,000 by GPC method.

Example 4
In Example 1, the polymerization catalyst was replaced with 5.4 g of a 90% lactic acid aqueous solution in which 0.5% by weight of germanium oxide was dissolved, the reaction temperature was increased to 230 ° C., and the system was gradually reduced in pressure, and the pressure was increased to 67 Pa over 90 minutes. The reaction was carried out in the same manner as in Example 1 except that polymerization was carried out for 3 hours while maintaining the degree of reduced pressure to obtain aliphatic polyester pellets. The obtained aliphatic polyester had a number average molecular weight in terms of polystyrene of 23,000 by GPC method.

Example 5
The same reactor as in Example 1 was charged with 76.9 g of succinic acid, 24.8 g of adipic acid and 85.7 g of 1,4-butanediol, and an esterification reaction was carried out for 90 minutes in the same manner as in Example 1. At this time, the esterification ratio was 90%. Thereafter, 0.2 g of tetrabutoxytitanium was added, the reaction temperature was raised to 240 ° C., and the system was gradually decompressed to 67 Pa over 90 minutes. The polymerization reaction was continued for 3.5 hours while maintaining the reduced pressure to obtain a polymer. The obtained polymer had a number average molecular weight in terms of polystyrene of 23,000 by the GPC method.

Example 6
The same reactor as in Example 1 was charged with 100.2 g of succinic acid, 88.7 g of 1,4-butanediol, and 0.25 g of malic acid, and subjected to an esterification reaction for 90 minutes in the same manner as in Example 1. At this time, the esterification ratio was 93%. At this time, 0.11 g of tetrabutoxytitanium was added, the reaction temperature was raised to 250 ° C., and thereafter the polymerization reaction was carried out for 3 hours in the same manner as in Example 1. The obtained polymer had a number average molecular weight in terms of polystyrene of 21,000 by the GPC method.

Example 7
The same reactor as in Example 1 was charged with 100.2 g of succinic acid, 119 g of 1,4-butanediol, 5.4 g of a 90% aqueous lactic acid solution, and 0.21 g of malic acid, and an esterification reaction was performed for 90 minutes in the same manner as in Example 1. Was.
At this time, the esterification ratio was 92%. Thereafter, 0.2 g of tetrabutoxytitanium was added and polymerization was carried out for 3 hours in the same manner as in Example 6 to obtain a polymer. The obtained polymer had a polystyrene reduced number average molecular weight of 22,000 by GPC.

Example 8
The same reaction as in Example 6 was carried out except that the amount of 1,4-butanediol used in Example 6 was changed to 80.3 g, and the polymerization reaction was carried out for 4 hours to obtain a polymer. The obtained polymer had a number average molecular weight in terms of polystyrene of 21,000 by the GPC method.

Comparative Example 1
In the same reactor as in Example 1, 100.2 g of succinic acid, 88.7 g of 1,4-butanediol, and 5.4 g of a 90% aqueous lactic acid solution in which 1% by weight of germanium oxide was previously dissolved were charged. While stirring the contents of the container, nitrogen gas was introduced, the temperature was raised to 210 ° C. in a nitrogen gas atmosphere, and the reaction was carried out at this temperature for 90 minutes. Next, the reaction temperature was raised to 230 ° C., and the pressure of the system was gradually reduced to 67 Pa over 90 minutes. Further, polymerization was carried out for 4 hours while maintaining the reduced pressure. After the completion of the reaction, the molten polymer was drawn out from the reactor into a thread and cut into granules to obtain aliphatic polyester pellets. The obtained aliphatic polyester had a number average molecular weight in terms of polystyrene of 22,000 by the GPC method.

Comparative Example 2
The same reactor as in Example 1 was charged with 100.2 g of succinic acid, 88.7 g of 1,4-butanediol, and 0.11 g of tetrabutoxytitanium. While stirring the contents of the container, nitrogen gas was introduced, the temperature was raised to 210 ° C. in a nitrogen gas atmosphere, and the reaction was carried out at this temperature for 90 minutes. Next, the reaction temperature was raised to 230 ° C., and the pressure of the system was gradually reduced to 67 Pa over 90 minutes. Further, polymerization was carried out for 7 hours while maintaining the degree of reduced pressure. After the completion of the reaction, the molten polymer was drawn out from the reactor into a thread and cut into granules to obtain aliphatic polyester pellets. The obtained aliphatic polyester had a number average molecular weight in terms of polystyrene of 16,000 by a GPC method.

Comparative Example 3
In a reactor similar to that in Example 1, 100.2 g of succinic acid, 88.7 g of 1,4-butanediol, and 5.4 g of a 90% aqueous lactic acid solution in which 0.5% by weight of germanium oxide was previously dissolved were charged. While stirring the contents of the container, nitrogen gas was introduced, the temperature was raised to 210 ° C. in a nitrogen gas atmosphere, and the reaction was carried out at this temperature for 90 minutes. Next, the reaction temperature was raised to 230 ° C., and the pressure of the system was gradually reduced to 67 Pa over 90 minutes. Further, polymerization was carried out for 5 hours while maintaining the reduced pressure. After the completion of the reaction, the molten polymer was drawn out from the reactor into a thread and cut into granules to obtain aliphatic polyester pellets. The obtained aliphatic polyester had a number average molecular weight in terms of polystyrene of 20,000 as determined by GPC.

According to the production method of the present invention, it is possible to produce an aliphatic polyester having a high molecular weight, less generation of foreign matter and coloring, and improved thermal stability in a short time.

Claims (6)

In the method for producing an aliphatic polyester, after an aliphatic diol and an aliphatic dicarboxylic acid or a derivative thereof are subjected to an esterification reaction, when subsequently producing a fatty acid polyester by polymerization in the presence of a polymerization catalyst, A method for producing an aliphatic polyester, comprising adding a polymerization catalyst to an esterification reaction step in which the esterification reaction rate in the esterification reaction is 80% or less. 2. The method for producing an aliphatic polyester according to claim 1, wherein the aliphatic polyester has a number average molecular weight of 10,000 to 300,000 in terms of GPC polystyrene. 3. The process for producing an aliphatic polyester according to claim 1, wherein at least one metal compound selected from Ge, Ti, Sb, Mg, Hf and Zn is used as a polymerization catalyst. The method for producing an aliphatic polyester according to any one of claims 1 to 3, wherein the polymerization is carried out at a reduced pressure of 0.7 kPa to 10 Pa after the addition of the polymerization catalyst. The method for producing an aliphatic polyester according to any one of claims 1 to 4, wherein the aliphatic polyester contains an aliphatic diol and an aliphatic dicarboxylic acid or a derivative thereof as main components. The aliphatic diol is at least one selected from ethylene glycol, 1,4-butanediol, 1,3-propanediol and 1,4-cyclohexanedimethanol, and the aliphatic dicarboxylic acid or a derivative thereof is succinic acid or adipic acid. 6. The method for producing an aliphatic polyester according to claim 5, wherein the aliphatic polyester is at least one member selected from the group consisting of, sebacic acid, anhydrides and lower alkyl esters thereof.