CN100430428C - Use of clay minerals as polyester polycondensation catalyst - Google Patents

Abstract

The invention discloses the use of clay mineral as polyester polycondensation catalyst. The clay mineral is: the main components are SiO ₂ and Al ₂ O ₃ , the particle size is less than 200 mesh, and the structure is a layered or fibrous aluminosilicate mineral powder. The dissolution of the clay mineral in glycol at 210°C The amount is higher than 0.10wt%. The polycondensation catalyst of the invention is a natural mineral, does not contain heavy metals, is harmless to humans and animals, and is a novel polycondensation catalyst that meets environmental protection requirements. The polyethylene terephthalate and its copolymer prepared according to the invention have a carboxyl terminal content lower than 20 mmol/Kg and good thermal stability.

Description

Use of clay minerals as polyester polycondensation catalyst

technical field

The present invention relates to the use of clay minerals as polyester polycondensation catalysts.

Background technique

The method of synthesizing polyester can generally be divided into two stages. The first stage is the direct esterification reaction of dibasic carboxylic acid and dibasic alcohol or the transesterification reaction of a lower ester of dibasic carboxylic acid (such as dimethyl ester) with dibasic alcohol to generate dibasic carboxylic acid and dibasic alcohol. The esterification product of alcohol, the direct esterification reaction of dicarboxylic acid and dihydric alcohol does not require a catalyst, but the use of a catalyst can speed up the reaction, while the transesterification reaction requires a catalyst; the second stage is dicarboxylic acid and dihydric alcohol The esterified product is subjected to polycondensation under reduced pressure until high molecular weight polyester is produced. The polycondensation reaction requires an appropriate catalyst, and the commonly used polycondensation catalysts include metal compounds such as Sb, Ti, and Ge. Sb-based catalysts have good effects and are widely used. At present, more than 90% of PET production uses Sb-based catalysts, but Sb is a harmful heavy metal that does not meet environmental protection requirements. Currently, developed countries are facing increasing environmental pressure; Ti Although the catalytic activity of the catalyst is very high, there are many side reactions, and some organic titanate catalysts are very unstable and easy to be hydrolyzed, so the storage requirements are strict; Ge is a scarce metal in my country and is expensive, so Ge The cost of catalyst is high. In recent years, developed countries are working to develop some new polyester polycondensation catalysts to replace the traditional catalysts currently used.

Contents of the invention

The object of the present invention is to provide the use of clay mineral as polyester polycondensation catalyst.

The clay minerals described in the present invention are: aluminosilicate mineral powders whose main components are SiO ₂ and Al ₂ O ₃ , whose particle size is less than 200 mesh, and whose structure is layered or fibrous. The dissolved amount is higher than 0.10wt% (relative to the dry mass of the catalyst itself), when used for polyester production, the catalyst can be dibasic alcohol (such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol or 1,4-cyclohexanedimethanol, etc.), the catalyst (dissolved in the diol part) is added in an amount of about 10ppm to 5000ppm (relative to the theoretical yield of polyester), preferably 50ppm to 3000ppm . It can also be added in the form of solid powder, the addition amount is 0.10wt% to 15wt% (relative to the theoretical yield of polyester), and the preferred addition amount is 0.10wt% to 10wt% (relative to the theoretical yield of polyester).

Specifically, the clay minerals described in the present invention mainly include kaolin, mica, montmorillonite, palygorskite, sepiolite, vermiculite, etc. and their mixtures in any proportion, preferably kaolin, mica, montmorillonite, palygorskite And their mixtures in any proportion, more preferably montmorillonite, most preferably sodium-based montmorillonite, calcium-based montmorillonite or their mixture in any proportion. All the minerals mentioned above can be obtained from commercial sources.

The polycondensation catalyst catalyzed polycondensation of polyester is a homogeneous reaction. It is generally believed that the catalyst is first dissolved in the reaction medium to form alcoholates of dihydric alcohols and then catalyzes polycondensation. Therefore, the higher the solubility of the clay mineral catalyst in the glycol, the higher the catalytic activity. The determination method of its dissolving amount in dibasic alcohol is as follows: dibasic alcohol and viscose catalyst are mixed with the mass ratio of 25 to 1, reflux at 210 ℃, inert gas protection, centrifuge with centrifuge after stirring for 2 hours, and settle After the material is fully dried, it is weighed, and the dissolved amount of the catalyst is determined according to the decrease of its mass. Because the production standards of different commercially available clay mineral products are different, the polyester polycondensation catalyst of the present invention should be selected from the clay mineral whose dissolving amount in glycol is higher than 0.10wt% (relative to the dry clay quality), preferably Clay minerals with a dissolved amount greater than 0.50% by weight.

When the clay mineral is in use, the smaller the particles are, the higher its solubility in dihydric alcohol is, and the higher the catalytic activity of the catalyst per unit mass is. Therefore, the clay mineral should be ground into a powder of 200 mesh or more, preferably 300 mesh or more.

The clay mineral catalyst can be added at any time before the start of the polycondensation reaction. During use, in order to ensure product quality, common additives can be added, such as colorants, matting agents, chain branching agents, stabilizers, etc., and their dosage and usage are the same as conventional methods.

Polyesters suitable for use in the present invention may include terephthalic acid (dimethyl ester), 2,6-naphthalene dicarboxylic acid (dimethyl ester) in combination with ethylene glycol, 1,3-propanediol, 1,4-butanediol or 1 , the polycondensation product or copolycondensation product of 4-cyclohexanedimethanol, and also the copolymerization of these dicarboxylic acids (dimethyl esters) and glycols with other dicarboxylic acids (dimethyl esters) or glycols These other dicarboxylic acids (dimethyl esters) or glycols are isophthalic acid (dimethyl esters), p-hydroxybenzoic acid, 4,4'-biphenyl dicarboxylic acid, diethylene glycol, molecular weight Polyethylene glycol below 2000, polytetrahydrofuran ether with a molecular weight below 3000, etc. The preferred polyester is polyethylene terephthalate.

The polycondensation catalyst of the present invention is a natural mineral, the catalyst has the characteristics of no heavy metal, harmless to humans and animals, and is a novel polycondensation catalyst that meets environmental protection requirements. The polyethylene terephthalate and its copolymer prepared according to the invention are characterized in that the carboxyl end content is lower than 20 mmol/Kg, does not contain heavy metals, and has good thermal stability.

Detailed ways

The following examples illustrate embodiments of the invention. Some parameters in the examples were measured as follows.

Intrinsic viscosity (I.V.): 0.1250 g polyester dissolved in 25 ml phenol/1,1,2,2-tetrachloroethane (1/1 wt) mixed solvent, measured at 25°C.

Terminal carboxyl group concentration: A small amount of polyester is dissolved in benzyl alcohol and measured by acid-base titration with 0.01N potassium hydroxide ethylene glycol solution using phenol red as indicator.

Example 1

Disperse 6.0g of 300 mesh sodium-based montmorillonite powder in 150g of ethylene glycol, reflux at 210°C for 2 hours under nitrogen protection, cool to room temperature, and centrifuge with a centrifuge to separate the mass of the settled solid after drying to determine the quality of montmorillonite. The dissolving amount of the compound is 3.05wt% (relative to the dry powder of montmorillonite), and 75.3g of the supernatant clear night is dropped into a nitrogen-filled reactor together with 100.7g of dimethyl terephthalate and 0.0100g of zinc acetate, and the temperature is raised to 200°C. After 95% of the theoretical amount of methanol is distilled off, heat up to 280°C, vacuumize, polycondense at a pressure lower than 200Pa for 1.5 hours, add 0.10 g of triphenyl phosphite, polycondense for 1.5 hours, and the reaction ends , The obtained polyester A was colorless and transparent. Using 0.0300g Sb ₂ O ₃ as polycondensation catalyst, pure polyester B was prepared by the same process. The melting points of A and B measured by DSC at a heating rate of 20 °C/min are 255.7 °C and 256 °C respectively, and analyzed by TGA at a heating rate of 20 °C/min. It is 12°C higher than polyester B; the IV of A and B are 0.66 and 0.63 respectively, and the carboxyl terminal concentration is 14mmol/Kg and 22mmol/Kg.

Example 2

3.0g 220 mesh calcium-based montmorillonite powder, 90g dimethyl terephthalate, 10g dimethyl 2,6-naphthalene dicarboxylate and 72g ethylene glycol are put into a reactor with nitrogen gas, and the temperature is raised to 200°C until 95 After % of the theoretical amount of methyl alcohol was distilled off, the temperature was raised to 280° C., vacuumized, and after polycondensation for 1.5 hours under the condition that the pressure was lower than 200 Pa, 0.10 gram of triphenyl phosphite was added, and after polycondensation for 1.5 hours, the reaction was terminated to obtain Copolyester. Its melting point is 245.2°C as determined by DSC at a heating rate of 20°C/min. A broad crystallization peak appears at about 177°C on the cooling curve, indicating that the crystallization ability of the copolymer has decreased. Its I.V. is measured to be 0.70 and the concentration of terminal carboxyl groups It is 12mmol/Kg.

Example 3

Disperse 6.0g of 400 mesh kaolin powder in 150g of ethylene glycol, reflux at 210°C for 2 hours under nitrogen protection, cool to room temperature, and centrifuge to separate with a centrifuge. After measuring the quality of the settled solid after drying, the dissolved amount of kaolin is determined to be 2.85 wt% (relative to kaolin dry powder), take 45g of the upper clear night, 82g of terephthalic acid, and 4.4g of isophthalic acid and put them into a nitrogen-filled reactor, raise the temperature to 260°C, and put them under a pressure of ² to 2.8Kg/cm After esterification at low temperature for 4 hours, the temperature was raised to 275° C., vacuum was applied, and after polycondensation at a pressure lower than 200 Pa for 1.5 hours, 0.10 g of triphenyl phosphite was added, and after polycondensation for 2 hours, the reaction was completed. The melting point of the product was determined to be 243.2°C by DSC at a heating rate of 20°C/min. A broad crystallization peak appeared at about 169°C on the cooling curve, indicating that the crystallization ability of the copolymer decreased. Its IV was 0.64 after measurement, and the carboxyl group The concentration is 12mmol/Kg.

Example 4

131.8g of bishydroxyethyl terephthalate (BHET), 3.0g of 400-mesh mica powder and 10g of ethylene glycol were put into the reactor respectively, polycondensed for 2 hours at 280°C and the pressure was lower than 200Pa, and 0.10g of phosphorous acid was added Triphenyl ester, polycondensation finished reaction after 1.5 hours again. The I.V. of the product is 0.65, its carboxyl-terminal concentration is 11 mmol/Kg, and it is a milky white solid after crystallization. Measured by DSC at a cooling rate of 20°C/min, their crystallization temperature is 30°C higher than that of pure PET, indicating that the crystallization rate of the polyester is greatly improved, and its I.V. is measured to be 0.59.

Example 5

131.8g of BHET, 2.0g of 300 mesh sodium montmorillonite powder, 4.0g of 400 mesh mica powder and 30g of ethylene glycol were put into the reactor respectively, polycondensed at 280°C and the pressure lower than 200Pa for 1.5 hours, and added 0.10g of phosphorous acid Triphenyl ester, polycondensation finished reaction after 1.5 hours again. The material was analyzed at a heating rate of 20°C/min by TGA, and the results showed that the thermogravity onset temperature of the polyester was 15°C higher than that of pure polyester, showing good thermal stability; using DSC at 20°C/min Its crystallization temperature is more than 30°C higher than that of pure PET, which shows that its crystallization speed is greatly improved.

Example 6

3.0g 300 mesh calcium-based montmorillonite powder and 3.0g 300 mesh vermiculite powder were dispersed in 150g 1,4-butanediol, refluxed at 210°C for 2 hours under nitrogen protection, cooled to room temperature, and centrifuged with a centrifuge. Measure the quality of the settled solid after drying to determine that the dissolved amount of the clay is 2.20wt% (relative to the dry powder of the clay), and get 90g of the upper layer clear night, 88.5g of dimethyl terephthalate and 0.0100g of zinc acetate into a nitrogen reactor In the process, the temperature is raised to 200°C until 95% of the theoretical amount of methanol is distilled, then the temperature is raised to 260°C, vacuumized, and after polycondensation at a pressure lower than 200Pa for 2 hours, 0.10 g of triphenyl phosphite is added, and then After 2 hours of polycondensation, the reaction was terminated. The resulting polyester had a melting point of 223.7°C as measured by DSC at a heating rate of 20°C/min.

Claims (7)

1. the purposes of clay mineral as polyester polycondensation catalyst, described clay mineral is: main component is Al ₂O ₃And SiO ₂, granularity the order number more than 200 orders, structure is stratiform or fibrous aluminosilicate mineral powder, the meltage of this clay mineral in 210 ℃ dibasic alcohol is higher than 0.10wt%.

2. according to the purposes of the clay mineral as polyester polycondensation catalyst of claim 1, described clay mineral is the mixture of kaolin, mica, montmorillonite, slope thread soil, sepiolite, vermiculite or their arbitrary proportions.

3. according to the purposes that mineral are used as polyester polycondensation catalyst that is stained with of claim 2, described clay mineral is the mixture of kaolin, mica, polynite, polygorskite or their arbitrary proportions.

4. according to the purposes of the clay mineral as polyester polycondensation catalyst of claim 3, described clay mineral is polynite.

5. according to the purposes of the clay mineral as polyester polycondensation catalyst of claim 4, described clay mineral is the mixture of sodium-based montmorillonite, calcium-base montmorillonite or their arbitrary proportion.

6. according to the purposes of clay mineral as polyester polycondensation catalyst arbitrary among the claim 1-5, it is characterized in that the meltage of this clay mineral in 210 ℃ dibasic alcohol is higher than 0.50wt%.

7. according to the purposes of clay mineral as polyester polycondensation catalyst arbitrary among the claim 1-5, the order number that it is characterized in that described granularity is more than 300 orders.