JP2699802B2 - Method for producing high molecular weight aliphatic polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing a biodegradable, high-molecular-weight aliphatic polyester useful in various fields in which conventional polymers such as molded articles, films and fibers are used.

[0002]

2. Description of the Related Art Biodegradable polymers, that is, polymers that disintegrate in soil or water under the action of microorganisms, have attracted attention as one of the means for solving the plastic waste problem in recent years as biodegradable polymers. , Its appearance is strongly desired. At this stage, it is no exaggeration to say that the completely biodegradable polymers, apart from natural products, are still only aliphatic polyesters. However, it has been generally accepted that aliphatic polyesters do not have sufficient heat stability and are not very useful polymers with a high molecular weight.

[0003] The present inventors have repeated studies on increasing the molecular weight of aliphatic polyesters and have obtained some findings, one of which has already been proposed in Japanese Patent Application Laid-Open No. Hei 4-189822. JP-A-4-189822 discloses a method in which a specific amount of diisocyanate is reacted with a high-molecular-weight aliphatic polyester to further increase the molecular weight to a practically usable high-molecular range. This method is very useful for increasing the molecular weight, and reduces the molecular weight (number average) of the aliphatic polyester to two.
It was also confirmed that it was increased to 0000 or more, exhibited practical physical properties, and was biodegradable. However, with the progress of the subsequent research, the stage of practical use, in which workability is particularly a problem, has led to problems of generation of microgels and control of molecular weight distribution.

[0004] The microgel is 0.1% in the produced polymer.
The presence of this microgel greatly affects film formability, film appearance and physical properties, or filament formability, and also impairs the commercial value of the product. Significantly reduced. The presence of this microgel is also observed in polyolefins. In the case of polyolefins, however, it is said that the polygels occur due to the nature of the catalyst. On the other hand, polyesters which react a small amount of diisocyanate as described in JP-A-4-189822 are used. In this case, the microgel is formed by the reaction of the diisocyanate with the polyester at elevated temperatures. The urethane bond formed by the reaction between the isocyanate group and the hydroxyl group is thermally dissociable and is reduced by high-temperature stirring at 200 ° C. or higher, but is not completely eliminated.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a high molecular weight aliphatic polyester in which the control of molecular weight distribution and the generation of microgels, especially microgels, are solved.

[0006]

Means for Solving the Problems The present inventors have conducted studies to obtain an aliphatic polyester having a molecular weight having practically sufficient physical properties without generation of microgels without using isocyanates. As a result, a small amount of unsaturated groups are introduced into the polyester, and the resulting unsaturated aliphatic polyester is further added with an organic peroxide in a molten state of the polyester to add unsaturated groups in the polyester to each other. The present inventors have found that the above objects can be effectively achieved, physical properties are practically sufficient, and a high molecular weight aliphatic polyester free of microgel can be obtained, and the present invention has been completed.

That is, the first aspect of the present invention is that [I] (1) an aliphatic or cycloaliphatic glycol component and (2) 98 to 99.99 mol% of an aliphatic dicarboxylic acid or an acid anhydride thereof.
And unsaturated dicarboxylic acid or an acid anhydride thereof 0.01
[II] 0.1 to 5 parts by weight of an organic peroxide based on 100 parts by weight of an unsaturated aliphatic polyester having a weight average molecular weight of 20,000 or more obtained by reacting an acid component consisting of The present invention relates to a method for producing a high-molecular-weight aliphatic polyester, wherein a weight-average molecular weight is adjusted to 30,000 or more by adding a substance and reacting.

[0008] A second aspect of the present invention is the above-mentioned first aspect [1].
(1) an aliphatic or cycloaliphatic glycol component,
(2) When reacting an aliphatic dicarboxylic acid or an acid anhydride thereof and an unsaturated dicarboxylic acid or an acid anhydride thereof,
The first invention uses together at least one polyfunctional compound selected from the group consisting of polyhydric alcohols having three or more functions, polyhydric alcohols having three or more functions, and polyhydric carboxylic acids having three or more functions or acid anhydrides thereof and oxycarboxylic acids having three or more functions. And a process for producing the high molecular weight aliphatic polyester described.

It has long been known that saturated polyesters, especially rubbers, are crosslinked by a hydrogen abstraction reaction with an organic peroxide. In this case, it is well known that a tertiary carbon, that is, a structure in which one hydrogen is bonded to a carbon atom is required. The polyester having the structure as described above is, for example, a polyester using a glycol such as propylene glycol or 2-methylpropanediol-1,3 as at least one component of a raw material. Polyesters synthesized using glycols having only a methylene bond, such as ethylene glycol and 1,4-butanediol, do not have a tertiary carbon in the dicarboxylic acid component. It was confirmed that this would not happen. However, the present inventors have found that when an appropriate amount of unsaturated dicarboxylic acid or its acid anhydride is used, an addition reaction occurs in combination with an organic peroxide, and the molecular weight can be increased without gelation. The invention is significant.

The aliphatic polyester used in the method of the present invention comprises, as raw materials, (1) an aliphatic or cycloaliphatic glycol component, (2) an aliphatic dicarboxylic acid or an acid anhydride thereof and an unsaturated dicarboxylic acid or an acid thereof. An acid component comprising an anhydride, or (1) an aliphatic or cyclic aliphatic glycol component, and (2) an acid component comprising an aliphatic dicarboxylic acid or an acid anhydride thereof and an unsaturated dicarboxylic acid or an acid anhydride thereof, ( 3) using at least one polyfunctional compound selected from the group consisting of trifunctional or higher polyhydric alcohols, trifunctional or higher polycarboxylic acids or anhydrides thereof, and trifunctional or higher oxycarboxylic acids; The components are synthesized by esterification (dehydration condensation) followed by a deglycol reaction in the presence of a metal compound catalyst.

As the aliphatic or cycloaliphatic glycol component, a type that forms an amorphous polyester such as propylene glycol is used from the viewpoint that a melting point of 70 ° C. or more, which is the lower limit that can be molded into the formed polyester, and crystallinity are required. Difficult, for example, ethylene glycol, 1,4-
It is preferable to use butanediol, 1,4-cyclohexanedimethanol and the like. When these glycols and other glycols are used in combination, 1,6-hexanediol, decamethylene glycol, and the like may be used in combination if the melting point of the produced polyester can be maintained at 70 ° C. or higher.

As the dicarboxylic acid or an acid anhydride thereof for forming a polyester in combination with the above-mentioned glycol component, an aliphatic dicarboxylic acid or an acid anhydride thereof is used from the viewpoint of biodegradation. When the melting point of the aliphatic polyester is 70 ° C. or less, the moldability is significantly impaired. Therefore, succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid are used as aliphatic dicarboxylic acids or acid anhydrides thereof. And the like, and these may be used in combination. An aliphatic dicarboxylic acid having an odd number of carbon atoms or an acid anhydride thereof is not suitable because the melting point is lowered.

As the unsaturated dicarboxylic acid or its anhydride used in the present invention, for example, maleic anhydride, maleic acid, fumaric acid and itaconic acid are generally used and are commercially available. A dicarboxylic acid having a cyclic unsaturated bond such as endmethylenetetrahydrophthalic anhydride can be used in terms of crosslinking, but if the polyester is required to have crystallinity, the structure may be disturbed depending on the amount used. It is not always appropriate.

The proportions of the aliphatic dicarboxylic acid or its anhydride and the unsaturated dicarboxylic acid or its anhydride are as follows:
When the number of moles of the entire polybasic acid component is 100 mol%, the aliphatic dicarboxylic acid or its acid anhydride 98 to 9
It consists of 9.99 mol%, preferably 99 to 99.9 mol%, and 0.01 to 2 mol%, preferably 0.1 to 1 mol% of unsaturated dicarboxylic acid or its anhydride. When the use ratio of the unsaturated dicarboxylic acid or the acid anhydride thereof is less than 0.01 mol%, it is substantially indistinguishable from the case where the unsaturated dicarboxylic acid or the acid anhydride is not used, and the use ratio is 2 mol%.
If it is larger, there is a high risk of gelation due to the addition of the organic peroxide. When the use ratio of the unsaturated dicarboxylic acid or its acid anhydride is in the range of 0.1 to 1 mol%, it is possible to increase the molecular weight and control the molecular weight distribution without gelling.

The proportion of the glycol component and the acid component used is preferably about 1.05 to 1.2 mol% with respect to 1 mol of the acid component.

In the present invention, when the aliphatic or cycloaliphatic glycol component is reacted with an acid component comprising an aliphatic dicarboxylic acid or an acid anhydride thereof and an unsaturated dicarboxylic acid or an acid anhydride thereof, a trifunctional compound is used. By using at least one polyfunctional compound selected from the group consisting of the above polyhydric alcohols, trifunctional or higher polycarboxylic acids or anhydrides thereof, and trifunctional or higher oxycarboxylic acids, for example, the When introduced, the molecular weight distribution of the polyester is expanded, and the melt viscosity required for molding a molded article can be adjusted.

Examples of trihydric or higher functional polyhydric alcohols include glycerin, trimethylolpropane, pentaerythritol, triallyl isocyanurate ethylene oxide adduct and the like. Glycidol, a monoepoxy compound in a dehydrated form, may also be used.

As the tri- or higher functional oxycarboxylic acid, any commercially available product can be used, but malic acid, tartaric acid, and citric acid are preferred from the viewpoint that they can be obtained at low cost.

Examples of trifunctional or higher polycarboxylic acids or anhydrides thereof include trimesic acid, propanetricarboxylic acid, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, cyclopentatetracarboxylic anhydride. Things. Particularly, trimellitic anhydride and pyromellitic anhydride are preferred.

The above-mentioned components of the polyfunctional compound can be mixed and used as required. The amount of the polyfunctional compound used is the total amount of the aliphatic dicarboxylic acid or its anhydride component.
The total amount is 0.1 to 5 mol% with respect to 00 mol%, and can be added from the beginning of esterification.

In the present invention, a glycol removal reaction is carried out to reduce the weight average molecular weight of the unsaturated aliphatic polyester to 2
Although it is necessary to be not less than 000, it is necessary to use a catalyst for the deglycolization reaction in combination. Examples thereof include an organic or inorganic metal compound of at least one metal selected from the group consisting of titanium, tin, antimony, cerium, germanium, zinc, cobalt, manganese, iron, aluminum, magnesium, calcium and strontium. And the amount used is 0.0 to 100 parts by weight of the resulting unsaturated aliphatic polyester.
01 to 0.5 part by weight. If the amount of the metal compound catalyst used is less than 0.001 part by weight, the deglycolization reaction will be slow and impractical, and if it is used more than 0.5 part by weight, the decomposition reaction will be strengthened, which is not preferable. Desirable amount depends on the type of metal, but 0.0
It is 0.5 to 0.2 parts by weight. As the metal compound catalyst,
For example, metal alkoxides, organic acid salts, chelates, oxides, and the like are used. In particular, organic compounds of titanium, for example, compounds such as alkyl titanate, titanium oxyacetylacetonate, and titanium oxalate are useful.
So-called biodegradable polyesters undergo microbial disintegration in the soil, but the metal catalyst or metal is likely to remain in the soil and must be of a safe type. From such a viewpoint, desirable metals include titanium, germanium, zinc, magnesium, calcium and the like.

The esterification reaction is carried out at 160-230 ° C., 5
It can be carried out for up to 16 hours, preferably under an inert gas atmosphere. If the temperature is lower than this temperature, the reaction rate is low and the practicality is poor. If the temperature is higher than this temperature, the risk of decomposition increases, and it is better to avoid it. Therefore, it is preferred to carry out the first stage esterification reaction at a temperature between 180 and 220 ° C. The esterification reaction is performed until the acid value of the unsaturated aliphatic polyester reaches 30 or less, preferably 15 or less, more preferably 10 or less. In this case, the higher the molecular weight, the more smoothly the molecular weight can be increased by the deglycolization reaction. The deglycolization reaction is carried out at 170 to 230 ° C. under a reduced pressure of 5 Torr or less.
Performed for 16 hours. More preferably, the reaction is carried out at 180 to 210 ° C. under a high vacuum of 1 Torr or less from the viewpoint of reaction rate and prevention of decomposition. The resulting polyester has essentially hydroxyl groups at the end groups and has an acid value of zero.

The unsaturated aliphatic polyester thus obtained must have a weight average molecular weight of 20,000 or more. If the weight average molecular weight is not more than 20,000, the effect of using the unsaturated dicarboxylic acid or its anhydride will be poor. If the weight-average molecular weight is less than 20,000, the effect of increasing the molecular weight cannot be expected unless the proportion of the unsaturated dicarboxylic acid or its anhydride used is more than 2 mol%, but the unsaturated dicarboxylic acid or Increased use of the acid anhydride adversely affects moldability. That is, when the proportion of the unsaturated dicarboxylic acid or its anhydride used increases, it becomes difficult to control the melt flow rate, and the brittleness appears even if the physical properties of the molded article are impaired. In short, the properties of the thermoplastic polymer are impaired and the properties of the thermosetting resin are added. Accordingly, the ability to form a film becomes extremely difficult. In the present invention, the molecular weight is weight-averaged because it is dominant in moldability and melt viscosity.

In the present invention, subsequently, an organic peroxide is added to the unsaturated aliphatic polyester having a weight average molecular weight of 20,000 or more, and the mixture is reacted to obtain a weight average molecular weight of 30,000.
000 or more. The organic peroxide used for this purpose is not particularly limited, but for the present invention, a high-temperature decomposition type, such as dialkyl peroxides such as dicumyl peroxide and peroxyesters such as t-butyl perbenzoate, is preferable. Used for

The organic peroxide is used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the unsaturated aliphatic polyester.
Preferably it is 0.5 to 3 parts by weight. If the amount of the organic peroxide is less than 0.1 part by weight, the effect of the addition is poor as a practical problem, and even if the amount exceeds 5 parts by weight, no particular improvement in the effect can be expected.

The addition of the organic peroxide to the unsaturated aliphatic polyester is preferably performed in the molten state of the unsaturated aliphatic polyester. As a result, unsaturated groups in the unsaturated polyester are added to each other, and the weight average molecular weight becomes 30,0.
00 or more.

If the weight average molecular weight of the high molecular weight aliphatic polyester obtained by adding an organic peroxide to the unsaturated aliphatic polyester and reacting is less than 30,000, the melt viscosity for molding a desired molded article is reduced. Is not enough.

The high molecular weight aliphatic polyester of the present invention comprises
It is biodegradable and applicable to various uses. When the high molecular weight aliphatic polyester of the present invention is put to practical use, it is needless to say that organic or inorganic fillers, reinforcing materials, polymers, lubricants, coloring agents, plasticizers, and the like can be used in combination.

[0029]

EXAMPLES Next, examples will be shown below to facilitate understanding of the present invention.

The melting point was measured by a DSC (differential scanning calorimeter) method. The molecular weight was measured by the following GPC measurement. Shodex GPC SYSTEM-11 Eluent CF ₃ COONa 5 mmol / HFIP (hexafluoroisopropanol, 1 liter) Column Sample column HFIP-800P HFIP-80M × 2 Reference column HFIP-800R × 2 Column temperature 40 ° C. Flow rate 1.0 ml / min Detector Shodex RI STD: PMMA (Shodex STANDARD
M-75)

Example 1 200 g of 1,4-butanediol, 222 g of succinic acid and 2.4 g of fumaric acid were charged into a 1-liter separable flask equipped with a stirrer, a fractionating condenser, a thermometer and a gas inlet tube. After esterification at 195 to 200 ° C. in a nitrogen stream to an acid value of 7.9, 0.05 g of tetraisopropyl titanate was added, and the condenser was replaced.
A glycol removal reaction was finally performed at 220 ° C. under a reduced pressure of 0.6 Torr for 6 hours. The obtained polyester (a)
Is a white wax-like crystal having a number average molecular weight of 14,
000, weight average molecular weight of 36,000, melting point of about 11
3 ° C.

300 g of the polyester (a) was placed in another flask, heated and melted at 200 ° C. under a nitrogen stream, 1.5 g of dicumyl peroxide was added, and the mixture was further stirred for 5 minutes.
It was poured into a metal vat and solidified. The number average molecular weight of the obtained crosslinked polyester (A) was 26,100, the weight average molecular weight was 119,000, and the melting point was about 115 ° C.

The polyester (A) was press-molded to form a sheet having a thickness of about 70 μm, but no generation of microgel was observed. When a test piece of 2.5 cm × 15 cm was buried about 20 cm below the soil of the tennis court and allowed to stand, it was found to be tattered after 6 months without stopping its original shape, confirming that it had biodegradability.

Example 2 In a 1-liter separable flask equipped with a stirrer, a fractionating condenser, a thermometer and a gas inlet tube, 204 g of ethylene glycol, 298 g of succinic anhydride and 6 g of itaconic acid were placed.
After esterification in a nitrogen stream at 195 to 200 ° C to an acid value of 9.4, 0.05 g of tetraisopropyl titanate was added, and finally at 215 to 220 ° C under a reduced pressure of 0.5 Torr for 10 hours. A glycol removal reaction was performed. The obtained polyester (b) is white crystalline, has a number average molecular weight of 22,900 and a weight average molecular weight of 6
The melting point was about 2,000.

After weighing 300 g of the polyester (b) in a separate flask and heating and melting it at 200 ° C. in a nitrogen stream,
4.5 g of t-butyl perbenzoate were added. The polyester (B) obtained by stirring until foaming was completed had a melting point of 105 ° C., a number average molecular weight of 31,000, and a weight average molecular weight of 133,000.

In the sheet having a thickness of about 100 μ obtained by molding in the same manner as in Example 1, generation of microgel was not recognized. When this was subjected to an activated sludge immersion test in an aeration tank, it was almost completely decomposed after 60 days, and was broken and did not stop its original form.

Example 3 In a 1-liter separable flask equipped with a stirrer, a distillation condenser, a thermometer and a gas inlet tube, 310 g of 1,4-cyclohexanedimethanol, 290 g of adipic acid,
2 g of maleic anhydride and 2 g of trimethylolpropane were charged and esterified at 190 to 195 ° C. in a stream of nitrogen to an acid value of 8.8.
After adding 0.05 g, the mixture was further reacted at 215 to 220 ° C. and finally under a reduced pressure of 0.6 Torr for 6 hours. The obtained polyester (C-1) is a white crystal having an ivory color,
The melting point was about 105 ° C., the number average molecular weight was 13,900, and the weight average molecular weight was 42,800.

300 g of polyester (C-1) was weighed into another flask, melted at 200 ° C. in a nitrogen gas stream, and 6 g of cumene hydroperoxide was added. After stirring at 200 ° C. for 30 minutes, the number average molecular weight of the obtained polyester (C-2) was 20,200 and the weight average molecular weight was 14
The melting point was 5,000, and the melting point was about 108 ° C.

The polyester (C-2) was molded in the same manner as in Example 1 to obtain a sheet having a thickness of about 100 μm. No microgel was found on the sheet. Example 1
Similarly, when buried in the soil and examined for biodegradability, after 6 months, countless insect-like holes were observed on the surface, confirming that it was biodegradable.

[0040]

According to the method of the present invention, it is possible to provide a biodegradable, high-molecular-weight aliphatic polyester which does not generate microgels and can be formed into molded articles, films, fibers and the like.

Claims (2)

(57) [Claims] 1. [I] (1) an aliphatic or cycloaliphatic glycol component, (2) 98 to 99.99 mol% of an aliphatic dicarboxylic acid or an acid anhydride thereof and an unsaturated dicarboxylic acid or an acid anhydride thereof The weight average molecular weight obtained by reacting with an acid component consisting of 0.01 to 2 mol% is 20,000.
[II] 0.1 to 5 parts by weight of an organic peroxide is added to 100 parts by weight of the unsaturated aliphatic polyester of 0 or more and reacted to make the weight average molecular weight be 30,000 or more. A method for producing a high-molecular-weight aliphatic polyester characterized by the following. 2. In the reaction of (1) (1) an aliphatic or cycloaliphatic glycol component with (2) an aliphatic dicarboxylic acid or an acid anhydride thereof and an unsaturated dicarboxylic acid or an acid anhydride thereof, 3. The method according to claim 1, wherein at least one polyfunctional compound selected from the group consisting of a trifunctional or higher polyhydric alcohol, a trifunctional or higher polycarboxylic acid or an acid anhydride thereof, and a trifunctional or higher oxycarboxylic acid is used. 3. The method for producing a high-molecular-weight aliphatic polyester described in 1. above.