阅读说明：本技术 使用添加剂制备聚酯的方法 (Process for preparing polyesters using additives ) 是由 H·巴赫曼 R·林克 E·赛德尔 M·冷泉 R·萨班迪 于 2017-07-06 设计创作，主要内容包括：本申请涉及减少聚酯羟端基的量的方法,其中,聚酯由至少一种二羧酸和至少一种二羟基醇以及至少一种选自二羧酸酐和/或单异氰酸酯的添加剂来制备,所述添加剂在制备聚酯的过程中和/或之后加入。(The present application relates to a process for reducing the amount of hydroxyl end groups of a polyester, wherein the polyester is prepared from at least one dicarboxylic acid and at least one dihydroxy alcohol and at least one additive selected from dicarboxylic anhydrides and/or monoisocyanates, which is added during and/or after the preparation of the polyester.)

1. a process for reducing the amount of hydroxyl end groups of a polyester,

with at least one dicarboxylic acid and at least one dihydric alcohol, and

at least one additive selected from carboxylic anhydrides and/or mono-isocyanates.

2. The process according to claim 1, wherein the additives are added during the prepolycondensation step and/or during the polycondensation step and/or after polycondensation.

3. The process as claimed in claim 1, wherein the carboxylic acid anhydride used as additive has the same or a different basic hydrocarbon structure than the dicarboxylic acid used as monomer.

4. A process as claimed in any preceding claim, wherein the carboxylic acid anhydride is selected from the group consisting of: glutaric anhydride, acetic anhydride and succinic anhydride.

5. A process according to any one of the preceding claims wherein the mono-isocyanate is a phenyl isocyanate.

6. The process according to any one of the preceding claims, wherein the additive is added in an amount of 0.1 to 10%, preferably about 0.2 to 1.0%, relative to the final polyester.

7. The method of any of the preceding claims, wherein the polyester is made from a dicarboxylic acid compound and a diol compound, wherein the acid compound is

a) Having a structure of C_nH_2(n-1)O₄Linear dimer acids of the formula n is equal to or less than 40, such as oxalic, malonic, succinic, glutaric, adipic or pimelic acid, and/or

b) Dimer acids or dicarboxylic acids having rings, such as cyclohexanedicarboxylic acid;

c) it is also possible to use the (in particular methyl, ethyl, propyl or butyl) esters of these acids and the anhydrides (for example succinic anhydride),

these acids may be used alone or in combination of two or more,

among them, the diol compound is an aliphatic or alicyclic compound having two-OH groups.

8. The process according to any one of the preceding claims, wherein the polyester is prepared from a dicarboxylic acid compound such as:

terephthalic acid, isophthalic acid, 2, 6-naphthalenedicarboxylic acid, and furandicarboxylic acids having a furan ring and their respective (especially methyl, ethyl, propyl or butyrate) esters, and these acids may be used as a single compound or as a mixture of two or more compounds;

the diol compound having 2 to 10 carbon atoms is, for example:

ethylene glycol, 1, 3-propylene glycol, 1, 4-butanediol, neopentyl glycol, 1, 6-hexamethylene glycol or 1, 4-cyclohexanedimethanol, polyethylene glycols based on ethylene glycol or propylene glycol or 1, 4-butanediol, and polytetrahydrofuran (polytetramethylene ether glycol),

wherein the diols may be used alone or in a mixture of two or more diols.

9. Use of an additive selected from the group consisting of: dicarboxylic anhydrides and mono-isocyanates.

The prior art describes a number of processes for the preparation of polyesters, polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS) and polybutylene terephthalate (PBT). Generally, the corresponding dicarboxylic acid is reacted with a diol compound.

The polyesters obtained do not generally meet certain requirements. For example, the color quality should improve. In addition, the process should be carried out more quickly, the amount of Tetrahydrofuran (THF) should be reduced, and the amount of diol required should also be reduced. Furthermore, there is a need for products with less decomposition in the melt phase and for better controlled growth in the melt phase.

Various processes for preparing polyesters are known from the prior art (e.g.WO 96/15173, EP2268702, EP2628758, WO2014/067954 and CN102443149), wherein, in these processes, dicarboxylic anhydrides and/or mono-isocyanates are used.

In these processes, dicarboxylic acid anhydrides and finally di-isocyanates are used as monomers to form the polyesters. These compounds cannot be added as additives to the polyester production process to reduce the corresponding hydroxyl end groups, for example, as indicated by the ratio of hydroxyl end groups to carboxyl end groups.

The object of the present invention was therefore to provide a process for preparing polyesters in which the color quality is improved, the process proceeds faster, the amount of Tetrahydrofuran (THF) is reduced, the amount of diol required is reduced, and a lower decomposition in the melt phase and a more controlled growth in the melt phase are achieved.

This object is solved by a process for reducing the amount of hydroxyl end groups of polyesters, wherein

The polyester is prepared from at least one or more dicarboxylic acids and at least one or more dihydric alcohols, and

at least one additive selected from carboxylic anhydrides and/or monoisocyanates.

As carboxylic anhydrides, mono-and/or dicarboxylic anhydrides may be used.

The term "reducing the hydroxyl end groups of the polyester" means that the number of hydroxyl end groups of the polyester prepared by using the additive is less than that of the polyester without the additive. The amount of reduced hydroxyl end groups can be correlated with the amount of carboxyl end groups, for example expressed as the difference between hydroxyl end groups and carboxyl end groups or the ratio of hydroxyl end groups to carboxyl end groups.

The carboxylic acid anhydride may have 2 to 16 carbon atoms. The mono-isocyanate may have 2 to 10 carbon atoms.

The carboxylic acid anhydrides used as additives may have the same or different basic hydrocarbon structure than the dicarboxylic acids used as monomers.

In one embodiment of the process for preparing polyesters according to the invention, the carboxylic acid anhydride is preferably selected from the group consisting of: glutaric anhydride, acetic anhydride and succinic anhydride (succinic acid anhydride). Furthermore, the mono-isocyanate may be a phenyl isocyanate.

In one embodiment, the amount of additive may be 0.1 to 10.0 wt.%, preferably about 0.2 to 1.0 wt.%, relative to the final polyester.

By the process according to the invention, the proportion of hydroxyl end groups (OH end groups) relative to carboxyl end groups (COOH end groups) can be reduced by reaction of dicarboxylic anhydrides and/or mono-isocyanates, in particular during or after the prepolycondensation and/or polycondensation, wherein, for example, during the production of products obtained with 1, 4-Butanediol (BDO) as monomer, the colour and stability are improved and the by-product Tetrahydrofuran (THF) is reduced.

For PBAT and PBS, dicarboxylic anhydrides are known monomers that cannot be effectively used as additives to reduce OH end groups. In contrast, according to the invention, the addition of additives at a later stage of the process (for example during or after polycondensation) is suitable for reducing the OH end groups.

Other polycondensates and copolyesters based on acids and diols with and without different comonomers can also be used according to the preparation process of the invention for the synthesis of all components (recipe) of the polyesters, in particular PBAT, PBS or PBT.

All process steps and operating parameters are known to the person skilled in the art. For example, the following process parameters, in particular the process parameters described in the examples below, can be used, wherein it is to be noted that individual process parameters are not irrespectively connected to other parameters, so that the process of the invention can be carried out if a specific parameter is selected and combined with other parameters.

The process of the present invention allows for both discontinuous and continuous production of polyester.

Hereinafter, components used in the method of preparing polyester are described.

Examples of aliphatic dicarboxylic acids are those of the formula CnH_2(n-1)O₄And n is equal to or less than 40, for example: oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, or pimelic acid, and may also be dimer acids or dicarboxylic acids having a ring like cyclohexanedicarboxylic acid. It is also possible to use, in particular, methyl, ethyl, propyl or butyl esters of these acids and also anhydrides, for example succinic anhydride. The acid may be used as a single compound or as a mixture of two or more compounds.

Aromatic carboxylic acids such as: terephthalic acid, isophthalic acid, 2, 6-naphthalenedicarboxylic acid, and acids having a furan ring, such as furandicarboxylic acid and their respective (especially methyl, ethyl, propyl or butyl) esters. The acid may be used as a single compound or as a mixture of two or more compounds.

The diol may use an aliphatic or alicyclic compound having two-OH groups. Aliphatic diols having from 2 to 10 carbon atoms are preferred, for example ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, neopentyl glycol, 1, 6-hexamethylene glycol or 1, 4-cyclohexanedimethanol, polyethylene glycols based on ethylene glycol or trimethylene glycol or 1, 4-butanediol and polytetrahydrofuran (polytetramethylene ether glycol). The diols may be used alone or as a mixture of two or more diols.

The catalyst according to the process of the invention can be used in two steps. Known metals and organometallic compounds can be used as catalysts. Preferably a titanium catalyst or an organometallic titanium compound such as tetrabutyl titanate (tetrabutyl titanate).

To improve the elastomeric properties of the polymer polyols, polyethylene glycol, polypropylene glycol or polytetramethylene ether glycol having a molecular weight of 250-4000g/mol, for example, can be added in a concentration of 0.01-40 mol%, in particular 0.01-5 mol%, based on the sum of the acid and the glycol.

To improve or modify the mechanical properties of the resulting polyester, branching agents may be used. Examples are trihydric or higher alcohols (e.g. glycerol, pentaerythritol) or suitable tribasic acids (e.g. propane-1, 2, 3-tricarboxylic acid) and/or anhydrides (e.g. trimellitic anhydride) or tribasic or higher hydroxycarboxylic acids (e.g. malic acid, citric acid, hydroxyisophthalic acid).

In the process of the present invention, a stabilizer may be used. Phosphorus compounds can be used as stabilizers. An example of a stabilizer is phosphoric acid (H)₃PO₄) Triethyl phosphonoacetate (TEPA), tris (ethylene glycol) phosphate (TEGPA) or 3-phosphonopropionic acid (CEPA).

Biodegradable PBAT made from butanediol, terephthalic acid and adipic acid can be made according to the following formulation:

(a) monomer (b): 1, 4-Butanediol (BDO), terephthalic acid (PTA), adipic acid (ADA);

(b) polyols for improved elasticity (e.g.polyethylene glycol or polytetramethylene ether glycol with a molecular weight of 250-4000g/kg PBAT);

(c) pentaerythritol or glycerol with a molecular weight of 0.01-50g/kg PBAT as branching agent; phosphorus-containing compounds as stabilizers, e.g. triethyl phosphonoacetate (TEPA), tris (ethylene glycol) phosphate (TEGPA), phosphoric acid (H)₃PO4) each containing 5 to 200ppm P;

(d) the catalysts used for the esterification and polycondensation reactions, which may be chosen from different types or the same catalysts;

(e) the above-mentioned additives for reducing the amount of OH end groups, in particular glutaric anhydride, acetic anhydride, succinic anhydride or phenyl isocyanate; and

(f) optionally hexamethylene diisocyanate or another chain extender to increase chain length and decrease end groups.

In one embodiment, a method of making a polyester may comprise the steps of: (transesterification) esterification, prepolycondensation and polycondensation. These are common steps in the preparation of polyesters and the skilled person therefore knows how they are to be carried out. In particular, the additives may be added during the prepolycondensation and/or polycondensation step and/or after polycondensation.

Furthermore, the present invention relates to the use of the above-mentioned additive selected from the group consisting of: carboxylic acid anhydrides or mono-isocyanates.

Several advantages are achieved with the method according to the invention and the use according to the invention. The polyesters obtained do meet certain requirements. For example, the color quality is improved. The process proceeds faster, the amount of Tetrahydrofuran (THF) is reduced, and the amount of diol required is also reduced. Furthermore, less decomposition of the product in the melt phase is achieved and a more controlled growth in the melt phase is achieved.

The present invention is illustrated by the following examples, which should not be construed as limiting the invention thereto.

Example 1 and comparative example 1

From the start to the end of the reaction step, a 10l autoclave was used.

The following example 1 was carried out.

Esterification:

the components:

1385.1 terephthalic acid (PTA)

1089.4g butanediol (BDO, molar ratio 1: 1.45)

1460g Hombicast Hs-06 (titanium content 60ppm compared to the final polymer)

47.4g polyethylene glycol 400(PEG 400, 13kg/to)

2.55g pentaerythritol (0.7kg/to)

Esterification of PTA

The monomer and catalyst were placed in the reactor and stirred continuously. After inerting, the reaction kettle was heated. When the product temperature reached 195 ℃ (start measurement time), the pressure dropped to 400mbar in 15 minutes, while the product temperature further increased to 240 ℃. The esterification reaction was completed after 120 minutes.

Preparation of adipic acid solution in BDO

The components:

1319.5g adipic acid (ADA)

789.3g BDO (molar ratio 1.00)

BDO was injected into the vessel followed by adipic acid. The vessel was inertized with nitrogen. The mixture was heated to 160 ℃ under slight overpressure and stirred until the PTA esterification reaction was complete. During this time, adipic acid was dissolved in BDO.

And (3) continuously esterifying:

the adipic acid-BDO solution was fed to the esterification reactor over about 5 minutes. Due to the reduction in the feed and heating temperatures, the product temperature dropped to 190 ℃ and increased to 212 ℃ during the esterification carried out. A total of 160 minutes after the start time was measured, and the concentration yield indicated the end of the objective esterification reaction.

Pre-polycondensation:

the condensation system was switched from the esterification condenser to the pre-polycondensation cooling trap and the pressure was reduced to 150mbar in 5 minutes and further to 35mbar in 5 minutes. The target pressure was held constant for 10 minutes. The average temperature of the molten phase was 235 ℃. The total precondensation time was 20 minutes.

Addition of polycondensation catalyst:

2.07g of Tyzor TnBT catalyst (Dorf Ketal, 80ppm Ti relative to the final polymer) were then added and flashed in the reactor with 10g of BDO.

Polycondensation:

the condensing system is switched from the pre-condensation cooling trap to the condensation cooling trap. Within 15 minutes, the pressure was reduced to <1 mbar. The temperature during the polycondensation was 240 ℃.

After a polycondensation time of 190 minutes, 20g of succinic anhydride were fed to the polycondensation reaction in an amount of 0.55% (compared to the final polymer).

The polycondensation time was 340 minutes. After breaking the vacuum with nitrogen, the polymer was discharged under pressure and pelletized, the final polymer product having an intrinsic viscosity of 1.6 dl/g.

Comparative example 1 differs from example 1 in that succinic acid was not added. More details of example 1, particularly as compared to comparative example 1, are shown in table 1 below.

Briefly, the esterification reaction is first carried out with terephthalic acid, then adipic acid is fed with BDO and preheated to be charged to the pre-product for further reaction. Different molar ratios of butanediol to acid were chosen.

TABLE 1