阅读说明：本技术 一种发泡用pet、pet发泡材料及发泡材料的制备方法 (PET for foaming, PET foaming material and preparation method of foaming material ) 是由 李乃祥 樊云婷 潘小虎 庞道双 于 2018-05-30 设计创作，主要内容包括：本发明公开了一种改性PET,是以对苯二甲酸和乙二醇为主要原料采用直接酯化法制备而成的改性PET切片,在反应中加入稳定剂、支化剂、成核剂和催化剂。本发明公开了一种PET发泡材料,以改性PET为原料、以超临界CO<Sub>2</Sub>为发泡剂。本发明还公开了PET发泡材料的制备方法,包括：改性PET切片经干燥形成发泡原料；将发泡原料加入连续挤出发泡用挤出机,将超临界CO<Sub>2</Sub>注入挤出机,注气压力4～20MPa,PET熔体和超临界CO<Sub>2</Sub>在静态混合器中混合,挤出发泡成型得PET发泡材料。本发明改性PET黏度高、熔体强度高,同时满足发泡工艺的结晶性能要求；PET发泡材料具有中高发泡倍率、泡孔尺寸分布优良,且具有良好力学性能。(2 2 2 The invention discloses a modified PET, which is a modified PET slice prepared by taking terephthalic acid and ethylene glycol as main raw materials through a direct esterification method, and a stabilizing agent, a branching agent, a nucleating agent and a catalyst are added in the reaction.)

1. the modified PET is characterized in that the modified PET is a modified PET slice prepared by taking terephthalic acid and ethylene glycol as main raw materials and adopting a direct esterification method, wherein a stabilizer, a branching agent, a nucleating agent and a catalyst are added in the reaction process.

2. The modified PET as claimed in claim 1, wherein the direct esterification process comprises esterification, melt polycondensation and solid phase polycondensation; the terephthalic acid, the ethylene glycol, the stabilizer, the branching agent, the nucleating agent and the catalyst are added at the same time for reaction.

3. The modified PET as claimed in claim 1, which is prepared by the following process: putting terephthalic acid, ethylene glycol, a stabilizer, a branching agent, a nucleating agent and a catalyst into a reaction kettle, carrying out esterification reaction at the temperature of 220-265 ℃, vacuumizing for polycondensation when the water yield reaches more than 95% of the theoretical water yield, carrying out polycondensation for 1h under the conditions of a vacuum degree of 250-600 Pa and a temperature of 265-275 ℃, gradually adjusting the vacuum degree to 10-60 Pa, raising the temperature to 275-285 ℃, discharging, cooling, granulating and drying when the melt intrinsic viscosity is 0.65-0.75 dl/g, thus obtaining modified PET basic slices; and (3) putting the modified PET basic slices into a rotary drum device, gradually heating and crystallizing, carrying out solid-phase polycondensation reaction at 10-40 Pa and 215-230 ℃, and cooling after the reaction is finished to obtain the modified PET for foaming.

4. the modified PET as claimed in claim 1, wherein the modified PET has an intrinsic viscosity of 0.8 to 1.4 dL/g.

5. The modified PET as claimed in claim 1, wherein the amount of the ethylene glycol is 25-40 wt% of the modified PET chip; the usage amount of the terephthalic acid is 55-70 wt% of the modified PET slice.

6. The modified PET as claimed in claim 1, wherein the catalyst is one or more of antimony trioxide, antimony acetate, ethylene glycol antimony, germanium dioxide, tetra-n-butyl titanate, titanium potassium oxalate, manganese acetate and zinc acetate, preferably one or more of antimony trioxide, antimony acetate and ethylene glycol antimony; the amount of the catalyst is 0.015-0.06 wt% of the mass of the modified PET slice;

the stabilizer is one or a combination of more of phosphoric acid, polyphosphoric acid, trimethyl phosphate, triphenyl phosphite and other phosphoric acid esters; the using amount of the stabilizer is 0.0035-0.5 wt% of the modified PET slice quality;

the nucleating agent is one or a mixture of more of talcum powder, mica, barium sulfate, calcium carbonate, nano silicon dioxide, boron nitride and titanium dioxide; the using amount of the nucleating agent is 0.035-5 wt% of the modified PET slice.

7. the modified PET as claimed in claim 1, wherein the branching agent is one or a combination of glycerol, pentaerythritol, trimellitic anhydride, pyromellitic anhydride, glycerol carbonate, 5-methyl-5-hydroxymethylene-trimethylene carbonate and 5-ethyl-5-hydroxymethylene-trimethylene carbonate; the amount of the branching agent is 0.01 to 0.8 mol% of the molar amount of terephthalic acid.

8. The PET foam material is characterized in that the PET foam material is obtained by taking modified PET as a raw material and supercritical CO ₂ as a foaming agent through continuous production and extrusion.

9. The method for preparing PET foamed material according to claim 8, characterized by comprising the steps of:

Drying the modified PET slices at 100-160 ℃ for 4-8 h to form a foaming raw material;

Adding a foaming raw material into an extruder for continuous extrusion foaming, injecting supercritical CO ₂ into the extruder, fully mixing a PET melt and supercritical CO ₂ in a static mixer under the gas injection pressure of 4-20 MPa, and performing extrusion foaming molding to obtain a PET foaming material;

The extrusion foaming molding is four-section heating and comprises the following steps:

first zone temperature: 240-280 ℃;

Temperature in the second zone: 250 to 290 ℃;

Temperature of the third zone: 220-280 ℃;

Temperature in the fourth zone: 220-280 ℃;

Static mixer temperature: 220-280 ℃;

Head temperature: 220 to 280 ℃.

10. The method for preparing PET foaming material according to claim 9, characterized in that the extrusion foaming molding is four-stage heating, which comprises:

First zone temperature: 240-260 ℃;

temperature in the second zone: 260-280 ℃;

Temperature of the third zone: 250-270 ℃;

temperature in the fourth zone: 230-260 ℃;

Static mixer temperature: 220-260 ℃;

Head temperature: 220 to 260 ℃.

Technical Field

The invention belongs to the technical field of preparation of high polymer foaming materials, relates to modified PET for foaming, a PET foaming material prepared by taking the modified PET as a raw material and a preparation method thereof, and particularly relates to a PET foaming material based on supercritical CO ₂ extrusion foaming and a preparation method thereof.

Background

The polyethylene terephthalate (PET) foam material has the unique advantages of low density, high strength, low water absorption and good sound and heat insulation performance, can achieve the effect of obviously increasing the strength and the rigidity without increasing the weight when being used as a structural foam material, and is widely applied to the fields of wind power, rail traffic, ships and naval vessels and aerospace.

₂The conventional PET is a crystalline linear polymer, contains benzene rings on a main chain, has a highly regular molecular chain structure, has higher glass transition temperature and melting point, has lower molecular weight, narrower molecular weight distribution, very low melt viscosity and strength, is difficult to bear tensile stress during bubble growth in a foaming process, and is easy to cause cell breakage, collapse and merging, meanwhile, the conventional PET is extremely easy to degrade in a forming processing process at a temperature higher than the melting point, has low crystallization rate, causes a narrow PET foaming forming processing temperature region, and has a higher technical threshold for realizing continuous industrial production of a foaming process.

disclosure of Invention

The invention aims to provide a modified PET for continuously producing an extruded PET foaming material and a method for continuously producing the extruded PET foaming material by using the modified PET as a raw material and only using supercritical CO ₂ as a foaming agent without adding other foaming agents aiming at the defects in the prior art, thereby achieving the purposes of safety and environmental protection and greatly simplifying the production process.

the purpose of the invention is realized by the following technical scheme:

a modified PET is prepared from terephthalic acid and ethanediol through direct esterifying, and adding stabilizer, branching agent, nucleating agent and catalyst.

the direct esterification method comprises esterification reaction, melt polycondensation reaction and solid phase polycondensation reaction; the terephthalic acid, the ethylene glycol, the stabilizer, the branching agent, the nucleating agent and the catalyst are added at the same time for reaction.

The preparation method of the modified PET comprises the following steps: putting terephthalic acid, ethylene glycol, a catalyst, a stabilizer, a branching agent and a nucleating agent into a reaction kettle, carrying out esterification reaction at the temperature of 220-265 ℃, vacuumizing for polycondensation when the water yield reaches more than 95% of the theoretical water yield, carrying out polycondensation for 1h under the conditions that the vacuum degree is 250-600 Pa and the temperature is 265-275 ℃, gradually adjusting the vacuum degree to 10-60 Pa, raising the temperature to 275-285 ℃ for continuous polycondensation reaction, discharging, cooling, granulating and drying when the melt intrinsic viscosity is 0.65-0.75 dl/g, thus obtaining modified PET basic slices; and (3) putting the modified PET basic slices into a rotary drum device, gradually heating and crystallizing, carrying out solid-phase polycondensation reaction at 10-40 Pa and 215-230 ℃ for a certain time, and cooling to obtain the modified PET for foaming.

The intrinsic viscosity of the modified PET is 0.8-1.4 dL/g.

the using amount of the ethylene glycol is 25-40 wt% of the modified PET slice; the usage amount of the terephthalic acid is 55-70 wt% of the modified PET slice.

The catalyst is one or more than two of antimony trioxide, antimony acetate, ethylene glycol antimony, germanium dioxide, tetra-n-butyl titanate, titanium potassium oxalate, manganese acetate and zinc acetate, preferably one or more than two of antimony trioxide, antimony acetate and ethylene glycol antimony; the dosage of the catalyst is 0.015-0.06 wt% of the modified PET slice.

The stabilizer is one or a combination of more of phosphoric acid, polyphosphoric acid, trimethyl phosphate, triphenyl phosphite and other phosphoric acid esters; the dosage of the stabilizer is 0.0035-0.5 wt% of the quality of the modified PET chip.

The branching agent is one or the combination of two of glycerol, pentaerythritol, trimellitic anhydride, pyromellitic anhydride, glycerol carbonate, 5-methyl-5-hydroxymethylene-trimethylene carbonate and 5-ethyl-5-hydroxymethylene-trimethylene carbonate; the amount of the branching agent is 0.01 to 0.8 mol% of the molar amount of terephthalic acid.

The nucleating agent is one or a mixture of more of talcum powder, mica, barium sulfate, calcium carbonate, nano silicon dioxide, boron nitride and titanium dioxide; the using amount of the nucleating agent is 0.035-5 wt% of the modified PET slice.

the quality of the modified PET chips refers to the total amount of reaction products of terephthalic acid and ethylene glycol.

The invention also aims to provide a PET foam material, which is prepared by taking modified PET as a raw material and supercritical CO ₂ as a foaming agent through continuous production and extrusion.

the invention also aims to provide a preparation method of the PET foaming material, which comprises the following steps:

Drying the modified PET slices at 100-160 ℃ for 4-8 h to form a foaming raw material;

and (2) adding the foaming raw material into an extruder for continuous extrusion foaming, injecting supercritical CO ₂ into the extruder, fully mixing the PET melt and supercritical CO ₂ in a static mixer under the gas injection pressure of 4-20 MPa, and performing extrusion foaming molding to obtain the PET foaming material.

The extruder for continuous extrusion foaming is a double-order single-screw-single-screw tandem extruder, a double-order double-screw-single-screw tandem extruder or a single-order single-screw extruder.

the extrusion foaming molding is four-section heating and comprises the following steps:

first zone temperature: 240-280 ℃;

Temperature in the second zone: 250 to 290 ℃;

temperature of the third zone: 220-280 ℃;

Temperature in the fourth zone: 220-280 ℃;

Static mixer temperature: 220-280 ℃;

head temperature: 220 to 280 ℃.

Preferably, the extrusion foaming molding is four-stage heating, which respectively comprises the following steps:

first zone temperature: 240-260 ℃;

Temperature in the second zone: 260-280 ℃;

Temperature of the third zone: 250-270 ℃;

Temperature in the fourth zone: 230-260 ℃;

Static mixer temperature: 220-260 ℃;

Head temperature: 220 to 260 ℃.

By adopting the temperature setting, on one hand, the modified PET material is fully plasticized, so that the supercritical CO ₂ and the modified PET melt are uniformly mixed, the viscosity and the strength of the melt are ensured, and the foaming molding is facilitated.

Compared with the prior art, the invention has the beneficial effects that:

the branched modified PET with high viscosity and high melt strength is prepared by combining the branching technology with the solid phase polycondensation reaction technology, simultaneously meets the crystallization performance requirement of the foaming process, can be directly subjected to supercritical CO ₂ extrusion foaming processing, is highly continuous and stable in production process, safe and free of environmental pollution, is simpler and more convenient in foaming process, is suitable for industrial scale production, is only supercritical CO ₂ as the foaming agent, is free of other foaming agents, and has no influence on the use performance and use safety of the product.

The prepared PET foam material has medium and high foaming multiplying power, excellent cell size distribution, 60-90 kg/m ³ apparent density range, 6 x 10 ¹¹ -8 x 10 ¹¹/cm ³ cell density range and good mechanical property, and the PET foam material product can be widely applied to buildings, decorative materials (such as heat insulation materials and high-grade decorative materials replacing wood), wind power blade supporting and filling materials, structural materials of high-speed trains, ships, airplanes and public transportation systems, ground covering materials, such as floors, outdoor products and the like.

Drawings

FIG. 1 is a scanning electron micrograph of the PET foam obtained in example 1.

Detailed Description

The technical solution of the present invention is further described below with reference to specific embodiments. It should be understood that the following examples are illustrative of the present invention only and are not intended to limit the scope of the present invention. After reading the teaching of the present invention, the skilled in the art can make various changes or modifications to the invention, and these equivalents also fall within the scope of the claims appended to the present application.