CN100537658C - Preparation method of polyester/clay composite material - Google Patents

Abstract

This invention discloses a method for making polyester/clay composite material. We use clay mineral as catalyst of polyester polycondensation. Compared with the theoretical yield of polyester, we add 0. 10 to 50 weight percent clay mineral. So as the clay mineral catalysting polycondensation, polyester and clay could nanocomposite to produce polyester/clay composite material. With this invention, we need no other polycondensation catalysts, and this can simplify preparing method, reduce production costs. The production has very low carboxyl-termination content and very good thermal stability, also it is environment friendly.

Description

Preparation method of polyester/clay composite material

technical field

The present invention relates to the preparation method of polyester/clay composite material, particularly relate to a kind of in-situ composite method under the condition that does not add polycondensation catalyst with clay as polycondensation catalyst to prepare polyethylene terephthalate (PET) and A method for clay nanocomposites of its copolymers.

Background technique

The preparation methods for preparing polyester/clay composites can generally be divided into three categories: (1) melt blending; (2) solution blending; (3) in situ compounding. Melt blending is suitable for the production of high-filling organic-inorganic composite materials, but PET melt blending has high energy consumption, easy degradation, and large equipment loss; the solution blending method has low production efficiency, large raw material consumption, and high cost; The composite method realizes the composite of polyester and clay during polycondensation, which not only simplifies the preparation process, but also reduces the production cost.

Patents CN 1074427C and CN 1272513A both disclose methods for preparing polyester/clay nanocomposites by in-situ composite method, but both use traditional polycondensation catalysts, and the clay must be modified with an intercalation agent.

Contents of the invention

The purpose of the present invention is to provide the preparation method of polyester/clay composite material, utilize clay mineral as polyester polycondensation catalyst, make clay realize polyester and clay in-situ nanocomposite to prepare polyester/clay nano composite material while catalyzing polycondensation .

The preparation method of polyester/clay composite material of the present invention is characterized in that: adopt clay mineral as polyester polycondensation catalyst, relative to the theoretical yield of polyester, the addition of clay mineral is 0.10wt% to 50wt%, relatively The best addition amount is 0.10wt% to 15wt% (relative to the theoretical yield of polyester).

The clay can be added at any time before the polycondensation reaction starts. 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 the present invention may include terephthalic acid (dimethyl ester), 2,6-naphthalene dicarboxylic acid (dimethyl ester) in combination with ethylene glycol, 1,3-propylene glycol, 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 dihydric alcohols are isophthalic acid (dimethyl esters), p-hydroxybenzoic acid, 4,4'-biphenyl dicarboxylic acid, diethylene glycol, molecular weight Polyethylene glycol with a molecular weight lower than 2000, polytetrahydrofuran ether with a molecular weight lower than 3000, etc. The preferred polyester is polyethylene terephthalate and its copolymers.

The clay mineral of the present invention is: main component is SiO ₂ and Al ₂ O ₃ , particle size is less than 200 order, the structure is layered or fibrous aluminosilicate mineral powder, the glycol ( Such as ethylene glycol, 1,3-propanediol, 1,4-butanediol or 1,4-cyclohexanedimethanol, etc.), the dissolved amount is higher than 0.10wt% (relative to the dry mass of the catalyst itself), used for When producing the polyester/clay nanocomposite, the clay is added in an amount of 0.10wt% to 50wt% (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 clay catalyst are mixed with the mass ratio of 25 to 1, reflux at 210 ℃, inert gas protection, after stirring for 2 hours, centrifuge with a centrifuge to separate the sediment Weigh it after it is fully dried, and determine the dissolved amount of the catalyst according to the decrease in 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 for use in the clay mineral whose dissolving amount in glycol is higher than 0.10wt% (relative to the dry clay quality), preferably dissolving Clay minerals in amounts 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. From the perspective of preparing clay nanocomposites, the smaller the particles, the better the dispersion of clay. Therefore, the clay mineral should be ground into a powder of 200 mesh or more, preferably 300 mesh or more.

A major feature of the invention is that clay minerals can be used to catalyze polycondensation, and at the same time realize in-situ nanocomposite of polyester and clay, thereby obtaining polyester/clay nanocomposite material. The clay mineral catalyst of the present invention is a tiny particle formed by combining many nanoscale layered or fibrous structural units in a certain way. These tiny particles will dissolve in a small amount in glycol or reaction medium, but these structural units Without being destroyed, the macromolecules will intersperse in the space between them, weakening or even disappearing the force between them, resulting in the expansion of the spacing between the structural units or the random distribution in the matrix. This distribution morphology is nanoscale, that is to say, a nanocomposite material is formed.

The polyester/clay composite is prepared by the method of the present invention, and the clay may not be modified or modified on any surface, but in order to achieve a more uniform dispersion of the clay in the polyester, the clay mineral may be subjected to surface modification. The processing methods can be divided into the following categories: (1) exchange the exchangeable cations between the structural units with organic cations, such as organic ammonium ions, pyridinium ions, imidazolium ions, phosphonium ions, etc.; (2) Make the clay surface adsorb some organic matter, these organic matter can be macromolecule, also can be small molecule, have as polyacrylamide, polyacrylic acid, polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol etc.; Surface treatment, these coupling agents include silane coupling agents, titanium coupling agents, aluminum coupling agents, etc.; (4) The above methods are used in combination. The above treatment methods belong to the mature known public technology. The above treatment is carried out on the surface of the clay, as long as its dissolving amount in glycol does not significantly decrease, its catalytic activity will not be significantly affected.

Clay has the characteristics of not containing heavy metals and being harmless to humans and animals. Therefore, the polyester/clay nanocomposite prepared by the present invention also has the following characteristics and advantages while maintaining its original characteristics: (1) no need to add polycondensation catalyst , can simplify the preparation method and reduce the production cost; (2) no external catalyst, can improve the quality of the polyester/clay nanocomposite material, showing lower carboxyl terminal content and better thermal stability; (3) the traditional Sb salt is the most widely used polyester polycondensation catalyst. Sb is a harmful heavy metal, which is facing increasing environmental protection pressure in developed countries. Therefore, using clay as a polycondensation catalyst also has the advantage of environmental protection.

Description of drawings

Fig. 1 is the diffraction curves of Na-montmorillonite, sample C in Examples 1-5 and sample F in Examples 13-14. The results show that Na-montmorillonite is well dispersed in polyester, and after surface modification, the dispersion is further improved, which is shown as the position of d ₀₀₁ diffraction peak shifts to the low angle direction.

Detailed ways

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

Intrinsic viscosity (I.V.): 0.1250g polyester dissolved in 25ml phenol/1,1,2,2-tetrachloroethane (1/1wt) 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.

Embodiment 1-5

131.8g of bishydroxyethyl terephthalate (BHET), 1.0g of 400-mesh sodium-based montmorillonite powder and 15g of ethylene glycol were respectively put into a nitrogen-filled reactor, and polycondensed at 280°C and a pressure lower than 200Pa 1.5 hours, add 0.10g triphenyl phosphite, finish reaction after polycondensation 1.5 hours again, obtain the polyester/clay nano-composite material A of 1% montmorillonite content, then prepare respectively 2%, 3% by the same method Polyester/clay nanocomposites B and C with montmorillonite content. Pure polyester D was prepared by the same process with BHET and _0.0300 g _Sb2O3 . Polyester/clay nanocomposite E was prepared by the same process with 131.8g BHET, 3.0g Na-montmorillonite and _{0.0300g Sb2O3} . Polyester/clay nanocomposites A, B and C are analyzed by X-ray diffraction. When the content of montmorillonite is 1% and 2%, there is no diffraction peak in the range of 2θ angle below 10 degrees, indicating that the montmorillonite sheet has been The sample C with a montmorillonite content of 3% still has weak diffraction peaks in the range of 2θ angle below 7 degrees, but the position of the 001 diffraction peak has shifted significantly to the low angle direction compared with pure montmorillonite , should be exfoliated/intercalated hybrid nanocomposites.

Example 6

5.0g 220 mesh calcium-based montmorillonite powder, 90g dimethyl terephthalate and 10g dimethyl 2,6-naphthalene dicarboxylate are put into a nitrogen-filled reactor, and the temperature is raised to 200°C until 95% of the theoretical After a certain amount of methanol is distilled off, heat up to 280°C, vacuumize, polycondense at a pressure lower than 200 Pa for 1.5 hours, add 0.10 g of triphenyl phosphite, polycondense for another 1.5 hours, and the reaction ends to obtain 3% clay content of the copolyester/clay nanocomposite material, the copolyester/clay nanocomposite material is analyzed by X-ray diffraction, and there are weak diffraction peaks in the range of 2θ angle below 10 degrees, but the position of the d ₀₀₁ diffraction peak is the same as that of pure Compared with montmorillonite, there has been obvious displacement to the low angle direction, which should be exfoliation/intercalation hybrid nanocomposite. Its melting point is 245.5°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 IV is 0.70, and the concentration of terminal carboxyl groups It is 12mmol/Kg.

Example 7

Put 2.5g of 300 mesh mica powder, 82.1g of terephthalic acid, 4.4g of isophthalic acid and 44g of ethylene glycol into a nitrogen-filled reactor, raise the temperature to 260°C, and put it under the pressure of 2-2.8Kg/ ^cm3 Esterify for 4 hours, then heat up to 275°C, vacuumize, polycondense under the condition of pressure lower than 200Pa for 1.5 hours, add 0.10 g of triphenyl phosphite, and polycondense for 2 hours, the reaction is over, and the clay content is 2.5%. copolyester/clay nanocomposites. The copolyester/clay nanocomposite is analyzed by X-ray diffraction, and there are still weak diffraction peaks in the range of 2θ angle below 10 degrees, but the position of the d ₀₀₁ diffraction peak has shifted significantly to the low angle direction compared with pure mica , should be exfoliated/intercalated hybrid nanocomposites. Its melting point is 243.2°C as determined by DSC at a heating rate of 20°C/min, and a broad crystallization peak appears at about 169°C on the cooling curve, indicating that the crystallization ability of the copolymer has decreased. Its IV is 0.57, and the concentration of terminal carboxyl groups It is 12mmol/Kg.

Example 8

Put 3.0g of 400 mesh kaolin powder together with 88.2g of dimethyl terephthalate, 90g of 1,4-butanediol and 0.0100g of zinc acetate into a nitrogen-filled reactor, and raise the temperature to 200°C until 95% of the theoretical amount After the methanol is distilled off, heat up to 260°C, vacuumize, polycondense at a pressure lower than 200 Pa for 1.5 hours, add 0.10 g of triphenyl phosphite, and polycondense for 1.5 hours, the reaction is over, and the content of kaolin is 3%. The PBT/clay nanocomposite material, the polyester/clay nanocomposite material is analyzed by X-ray diffraction, and there are weak diffraction peaks in the range of 2θ angle below 10 degrees, but the position of the d ₀₀₁ diffraction peak is compared with that of pure kaolin, Significant displacement has occurred in the low-angle direction, which should be exfoliated/intercalated hybrid nanocomposites. Its melting point was determined to be 224.5°C by DSC at a heating rate of 20°C/min.

Examples 9-11

Put 131.8g of BHET, 0.50g of 400 mesh palygorskite powder and 10g of ethylene glycol into the reactor respectively, polycondense for 2 hours at 280°C and a pressure lower than 200Pa, add 0.10g of triphenyl phosphite, and polycondense for 1~ After 2 hours, the reaction was terminated to obtain polyester/clay nanocomposites with 0.5% palygorskite content, and then polyester/clay nanocomposites with 1% and 3% mica contents were prepared respectively by the same method. These materials were analyzed by TGA at a heating rate of 20°C/min. The results showed that the thermal weight loss onset temperature of polyester clay nanocomposites with palygorskite content of 0.5%, 1%, and 3% was higher than that of pure polyester. 5 ℃, 8 ℃ and 9 ℃, showing good thermal stability; the sample was observed by transmission electron microscope, when the palygorskite content was 0.5% and 1%, the palygorskite fibers were well dispersed and showed a random distribution shape , indicating that it has been peeled off. The sample with a palygorskite content of 3% is observed under the lens, and there are a large number of fiber bodies that have been peeled off, and there are also a small amount of aggregates that are not peeled off but whose size is less than 100 nanometers. The I.V. of these nanocomposites are 0.55, 0.59, 0.65 respectively, their carboxyl terminal concentrations are all lower than 15mmol/Kg, and they are milky white solids after crystallization. Measured by DSC at a cooling rate of 20°C/min, their crystallization temperature is more than 30°C higher than that of pure PET, indicating that the crystallization speed of these nanocomposites is greatly improved.

Example 12

131.8g of bishydroxyethyl terephthalate (BHET), 2.0g of 400-mesh sodium montmorillonite powder, 4.0g of 400-mesh vermiculite powder and 30g of ethylene glycol were put into the reactor respectively. Polycondensate under the condition of 200 Pa for 1.5 hours, add 0.10 g of triphenyl phosphite, and finish the reaction after polycondensation for 1 to 2 hours to obtain a polyester/clay nanocomposite material with a mixed clay content of 6%. The material was analyzed by TGA at a heating rate of 20°C/min. The results showed that the thermal weight loss onset temperature of the polyester/clay nanocomposite was 15°C higher than that of pure polyester, showing good thermal stability; According to X-ray diffraction analysis, there is still a diffraction peak within the range of 2θ angle below 10 degrees, indicating that the clay sheet has not been completely peeled off, but the position of the d ₀₀₁ diffraction peak is the same as that of pure montmorillonite or pure vermiculite. There has been an obvious displacement to the low angle direction, which should be the exfoliation/intercalation hybrid nanocomposite. The IV of the nanocomposite material is 0.62, and the carboxyl terminal concentration is 13mmol/Kg. Measured by DSC at a cooling rate of 20°C/min, its crystallization temperature is 30°C higher than that of pure PET, indicating that its crystallization rate is greatly improved.

Examples 13-14

Sodium montmorillonite was modified with hexadecyl pyridinium bromide and cationic polyacrylamide respectively, using water as the medium, and after being fully dried, it was treated with a toluene solution of KH570 silane coupling agent with a concentration of 0.1% wt. Grind into 400 mesh powder to obtain clay F and clay G. 131.8g of BHET, 4.0g of 400-mesh treated montmorillonite powder and 15g of ethylene glycol were put into the reactor respectively, polycondensed for 1.5 hours at 280°C and a pressure lower than 200Pa, and 0.10g of triphenyl phosphite was added, After another 1-2 hours of polycondensation, the reaction was terminated, and polyester/clay nanocomposites F (containing clay F) and G (containing clay G) with a content of 4% modified montmorillonite were respectively obtained. These materials were analyzed by TGA at a heating rate of 20 °C/min. The results showed that the thermogravity onset temperature of A and B clay nanocomposites was 11 °C and 10 °C higher than that of pure polyester, showing good thermal stability. According to X-ray diffraction analysis, there are still weak diffraction peaks in the range of 2θ angle below 10 degrees, but the position of d ₀₀₁ diffraction peak has shifted to the low angle direction compared with pure montmorillonite , should be exfoliated/intercalated hybrid nanocomposites. The IVs of these nanocomposites are 0.66 and 0.61, respectively, and the concentration of terminal carboxyl groups is lower than 15mmol/Kg. Measured by DSC at a cooling rate of 20°C/min, their crystallization temperature is more than 30°C higher than that of pure PET, indicating that the crystallization speed of these nanocomposites is greatly improved.

Table 1 shows some parameters of the polyester and polyester/clay nanocomposites of Examples 1-5.

Table 1

sample Clay content (wt%) Sb₂O₃(ppm) Onset temperature of thermogravity loss under N₂ atmosphere (℃) Crystallization temperature (°C) Terminal carboxyl group concentration (mmol/Kg) Intrinsic viscosity (dl/g) A 1 0 435 202 12 0.65 B 2 0 436 208 13 0.62 C 3 0 438 210 13 0.70 D. 0 300 427 170 twenty three 0.66 E. 3 300 434 211 37 0.67

The results in Table 1 show that using clay as a polycondensation catalyst to prepare polyester/clay nanocomposites not only significantly reduces the content of terminal carboxyl groups, but also improves thermal stability.

Claims (6)

1. the preparation method of polyester/clay composite material is characterized in that: adopt clay mineral as polyester polycondensation catalyst, relative to the theoretical yield of polyester, the addition of clay mineral is 0.10wt% to 15wt%; The polyester is terephthalic acid, dimethyl terephthalate, 2,6-naphthalene dicarboxylic acid, 2,6-dimethyl naphthalene dicarboxylate and ethylene glycol, 1,3-propylene glycol, 1,4 - polycondensation or copolycondensation products of butanediol or 1,4-cyclohexanedimethanol, these dicarboxylic acids, dimethyl dicarboxylates and dihydric alcohols with other dicarboxylic acids, dicarboxylic acids Copolymers of dimethyl esters or diols, these other dicarboxylic acids, dimethyl dicarboxylates or diols are isophthalic acid, dimethyl isophthalate, p-hydroxybenzoic acid, 4, 4'-biphenyl dicarboxylic acid, diethylene glycol, polyethylene glycol with a molecular weight lower than 2000, and polytetrahydrofuran ether with a molecular weight lower than 3000; 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 0.10 wt%. 2. according to the preparation method of claim 1, it is characterized in that: described polyester is polyethylene terephthalate and copolymer thereof. 3. The preparation method according to claim 1, characterized in that the clay mineral is kaolin, mica, montmorillonite, palygorskite, sepiolite, vermiculite and mixtures thereof in any proportion. 4. The preparation method according to claim 3, characterized in that the clay mineral is sodium-based montmorillonite, calcium-based montmorillonite or their mixture in any proportion. 5. The preparation method according to claim 1, 3 or 4, characterized in that: the dissolving amount of the clay mineral in glycol at 210°C is higher than 0.50wt%. 6. The preparation method according to claim 1, 3 or 4, characterized in that the clay mineral is subjected to surface modification treatment.

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