WO2021017580A1

WO2021017580A1 - Lightweight polystyrene foamed material having small pore diameter and preparation method therefor

Info

Publication number: WO2021017580A1
Application number: PCT/CN2020/090998
Authority: WO
Inventors: 赵玲; 胡冬冬; 强薇; 刘涛; 姚舜
Original assignee: 华东理工大学
Priority date: 2019-08-01
Filing date: 2020-05-19
Publication date: 2021-02-04
Also published as: CN111138773A

Abstract

Disclosed is a method for preparing a polystyrene foamed material, comprising the following steps: blending a polystyrene and a polydimethylsiloxane to obtain a polystyrene/polydimethylsiloxane blend; and foaming the polystyrene/polydimethylsiloxane blend under supercritical CO ₂ conditions, wherein the number average molecular weight of the polydimethylsiloxane can be 2,000 g/mol to 17,000 g/mol. The preparation method is simple in process, does not produce unpleasant odors and by-products, is environmentally friendly, and the additives are safe and environmentally friendly, and meets the requirements of developments in related fields. The polystyrene foamed material has a large nucleation density, a small foam cell diameter and a large foaming ratio, and is environmentally friendly.

Description

Lightweight polystyrene foam material with small aperture and preparation method thereof

This application claims the priority of the Chinese patent application 2019107074456 whose filing date is 2019/8/1. This application quotes the full text of the aforementioned Chinese patent application.

Technical field

The invention relates to a polystyrene foam material and a preparation method thereof.

Background technique

Polystyrene (PS) is an amorphous polymer with extremely high transparency, good electrical insulation, easy processing, and low cost. Because of these excellent characteristics, polystyrene foam products are widely used in food packaging, building insulation, product cushioning and shielding materials and other fields. At present, the main fluorine-containing physical blowing agents in the polystyrene foaming industry in my country, such as hydrochlorofluorocarbons (HCFC), hydrofluorocarbons (HFC) and hydrocarbons (HC), are due to their solubility in polymers It is high and the foaming process spreads slowly, and the obtained polystyrene foamed product has a higher magnification. However, because CFCs and HCFCs are harmful to the environment, the foreign foaming industry has turned to use environmentally friendly foaming agents for polymer foaming. The domestic foaming industry has also begun to promote the green polymer foaming process. the critical CO ₂ as compared to chlorofluorocarbon blowing agent compared, CO ODP ₂ (the ozone depletion value) is zero, non-toxic, safe, there is no problem recycling has become one of the mainstream substituted alkane CFC blowing agents.

In the past ten years, China’s polystyrene foaming industry has also begun to study supercritical CO ₂ foaming. At present, there are still the following thorny problems to be solved: Compared with HFC/HC/CFC and other foaming agents, CO _{2 is} in polymerization It has the disadvantages of low solubility and high resolution rate, and it is difficult to obtain polystyrene foamed materials with high foaming density and high foaming ratio, which limits the application of polystyrene. At present, the improvement of supercritical CO ₂ foamed polystyrene ratio mainly starts from two aspects. One is to improve the nucleation density by modifying the polymer foam matrix itself, such as nano-calcium carbonate, montmorillonite and other inorganic materials. Filler, or add pro-CO ₂ additives, such as fluorine-containing silicon-containing polymers, which can improve the interaction between the polymer matrix and CO ₂ , thereby enhancing the cell density of the foamed material, but adding a nucleating agent separately Can not significantly increase the expansion ratio of the foaming material; on the other hand, starting from improving the foaming agent, by adding a co-blowing agent to improve the foaming performance of CO ₂ , the overall solubility of the foaming agent in the polymer matrix is improved and the foaming is slowed down The analytical diffusion rate of the agent maintains a high solubility of the foaming agent inside the polymer matrix, thereby obtaining a polymer foam material with a higher foaming ratio.

Summary of the invention

The technical problem to be solved by the present invention is to overcome the prior art in the process of preparing polystyrene material by supercritical CO ₂ foaming, the solubility of CO ₂ in polystyrene is low, and the diffusion is fast, and the obtained polystyrene material has a pore size The invention provides a polystyrene foam material and a preparation method thereof. The preparation method has a simple process, does not produce bad smell and by-products, is good for the environment, and the additives are safe and environmentally friendly, and meet the development needs of related fields. The polystyrene foam material has a large nucleation density, a small cell diameter, a large expansion ratio, and is environmentally friendly.

In order to achieve the above objective, the present invention adopts the following technical solutions:

The invention provides a method for preparing a polystyrene foam material, which comprises the following steps: blending polystyrene and polydimethylsiloxane to obtain a polystyrene/polydimethylsiloxane blend物; The polystyrene / polydimethylsiloxane blend can be foamed under supercritical CO ₂ conditions; wherein, the polydimethylsiloxane number molecular weight can be 2000g/mol ~17000g/mol.

In the present invention, the molecular weight of the polydimethylsiloxane is preferably 2000 g/mol to 6000 g/mol, more preferably 2000 g/mol.

In the present invention, the content of the polydimethylsiloxane in the polystyrene/polydimethylsiloxane blend may be 0.5 to 1.5% by weight, preferably 1% by weight.

In the present invention, the polystyrene material may be conventional in the field, and preferably is Yangzi BASF Petrochemical 158K general-purpose polystyrene.

In the present invention, the operation and conditions of the blending can be conventional in the art, and the blending is generally performed in a Hack internal mixer conventional in the art.

In the present invention, the blending temperature is preferably 170-180°C, more preferably 170°C.

In the present invention, the blending time is preferably 15 to 20 minutes, more preferably 15 minutes.

In the present invention, the rotor speed in the blending is preferably 80-100 revolutions/min, more preferably 100 revolutions/min.

In the present invention, the polystyrene/polydimethylsiloxane blend may be a sheet.

In the present invention, the foaming under supercritical CO ₂ conditions is carried out according to the following steps: placing the polystyrene/polydimethylsiloxane blend in an autoclave and filling CO _{2 with} replacement air three times; The autoclave is heated to the foaming temperature, and after holding for half an hour, it is filled with supercritical CO _{2 to} set the pressure to saturate the polystyrene/polydimethylsiloxane blend; then the pressure is relieved, A polystyrene foam material is obtained.

In the present invention, the heating can be a conventional program temperature controlled heating in the field, and the heating rate can be 8-12°C/min, preferably 10°C/min.

In the present invention, the foaming temperature may be 105-115°C, preferably 110°C.

In the present invention, the pressure of the supercritical CO ₂ may be 14-15 MPa, preferably 15 MPa.

In the present invention, the saturation means that CO ₂ reaches a dissolution equilibrium inside the matrix of the polystyrene/polydimethylsiloxane blend, and the saturation time can be 1 to 2 hours, preferably 2h.

In the present invention, the operation and conditions of the pressure relief can be conventional in the art, and the average rate of the pressure relief is preferably 500-600 MPa/s, more preferably 500 MPa/s.

In the present invention, the preparation method of the polystyrene foam material further comprises: adding to the polystyrene/polydimethylsiloxane blend before the foaming under supercritical CO ₂ conditions Step of adding co-blowing agent.

In the present invention, the co-blowing agent may be absolute ethanol or n-pentane, wherein the purity of the n-pentane is >99.8%, preferably absolute ethanol.

In the present invention, the added amount of the co-blowing agent is 5-7 wt% of the supercritical CO ₂ under the foaming temperature and pressure, preferably 5 wt%.

The present invention also provides a preparation method of polystyrene foam material, which comprises the following steps: after adding a co-blowing agent to polystyrene, foaming is done under supercritical CO ₂ conditions.

In the present invention, the foaming under supercritical CO ₂ conditions is carried out as follows: the polystyrene and co-blowing agent are placed in an autoclave, filled with CO _{2 to} replace air three times; and the autoclave After heating to the foaming temperature and keeping it warm for half an hour, it is filled with supercritical CO _{2 to} set the pressure to saturate the polystyrene; then the pressure is released to obtain a polystyrene foam material.

The invention also provides a polystyrene/polydimethylsiloxane blend, which is composed of the following components in mass fractions: 98.5-99.5wt% polystyrene and 0.5-1.5wt% polydimethylsiloxane Siloxane; The polydimethylsiloxane has a number-weight molecular weight of 2000 g/mol to 17000 g/mol, preferably 2000 g/mol to 6000 g/mol, more preferably 2000 g/mol.

The invention also provides a polystyrene foam material prepared by the preparation method of the polystyrene foam material of the invention.

In the present invention, the cell diameter of the polystyrene foam material is less than 12μm, preferably less than 9μm; the cell expansion ratio is greater than 8 times, preferably greater than 11 times; the nucleation density is greater than 8.75×10 ⁹ cells /cm ³ , preferably greater than 10.1×10 ⁹ cells/cm ³ .

On the basis of conforming to common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain preferred examples of the present invention.

The reagents and raw materials used in the present invention are all commercially available.

The positive and progressive effects of the present invention are:

1. The present invention adopts simple blending to prepare foaming samples, the process is simple, no bad smell and by-products are generated, it is good for the environment, and the additives are safe and environmentally friendly;

2. According to the present invention, through polydimethylsiloxane, co-blowing agent or their synergistic effect, the obtained polystyrene foam material has the advantages of high foaming nucleation density, large foaming ratio, small cell diameter, etc. .

Description of the drawings

Figure 1 is a cross-sectional electron micrograph of the polystyrene foam product obtained in Example 1 of the present invention;

2 is a cross-sectional electron micrograph of a polystyrene foam product obtained in Example 2 of the present invention;

3 is a cross-sectional electron micrograph of the polystyrene foam product obtained in Example 3 of the present invention;

4 is a cross-sectional electron microscope view of the polystyrene foam product obtained in Example 4 of the present invention;

5 is a cross-sectional electron micrograph of a polystyrene foam product obtained in Example 5 of the present invention;

6 is a cross-sectional electron micrograph of a polystyrene foam product obtained in Example 6 of the present invention;

Figure 7 is an electron micrograph of a cross-section of a polystyrene foam product obtained in Example 7 of the present invention;

8 is a cross-sectional electron micrograph of a polystyrene foam product obtained in Comparative Example 1 of the present invention;

Figure 9 is an electron micrograph of a cross-section of a polystyrene foam product obtained in Comparative Example 2 of the present invention;

10 is a cross-sectional electron micrograph of a polystyrene foam product obtained in Comparative Example 3 of the present invention;

Figure 11 is an electron micrograph of a cross-section of the polystyrene foamed product obtained in Comparative Example 4 of the present invention.

Detailed ways

The present invention will be further described by way of examples below, but the present invention is not limited to the scope of the described examples. In the following examples, the experimental methods without specific conditions are selected according to conventional methods and conditions, or according to the product specification.

In the following examples, the polystyrene particles and polydimethylsiloxane are melt-blended through a Hack internal mixer, and after adding a co-blowing agent, they are foamed intermittently through an autoclave to obtain the desired foaming ratio and foam Polystyrene foam product with cell density and cell diameter.

Example 1

Put the polystyrene raw material and polydimethylsiloxane (with a molecular weight of 2000g/mol) into a Hack internal mixer for blending, the content of polydimethylsiloxane is 1wt%, and the blending temperature is 170 ℃, the blending time is 15 minutes, the torque speed is 100 revolutions/min, and the blending obtains a polystyrene/polydimethylsiloxane blend.

Place the blend in an autoclave, add the co-blowing agent absolute ethanol, add 5wt% of the mass of CO _{2 at the} experimental temperature and pressure, fill with CO _{2 to} replace air three times, and then program the autoclave for temperature control and heating. The heating rate is 10°C/min, and the foaming temperature is 110°C. After holding for half an hour, it is filled with high-pressure CO ₂ and the pressure is controlled to 15MPa. The blend is saturated for 2h, and then the pressure is quickly relieved. The pressure relief rate is 500MPa /s to obtain a microcellular foam material.

Example 2

Put the polystyrene raw material and polydimethylsiloxane (with a molecular weight of 6000g/mol) into a Hack internal mixer for blending, the content of polydimethylsiloxane is 1wt%, and the blending temperature is 170 ℃, the blending time is 15 minutes, the torque speed is 100 revolutions/min, and the blending obtains a polystyrene/polydimethylsiloxane blend.

Place the blend in an autoclave, add the co-blowing agent absolute ethanol, add 5wt% of the mass of CO _{2 at the} experimental temperature and pressure, fill with CO _{2 to} replace air three times, and then program the autoclave for temperature control and heating. The heating rate is 10°C/min, and the foaming temperature is 110°C. After holding for half an hour, it is filled with high-pressure CO ₂ and the pressure is controlled to 15 MPa to saturate the blend for 2 hours, and then perform rapid pressure relief. The pressure relief rate is 500 MPa /s to obtain a microcellular foam material.

Example 3

Place the blend in an autoclave, add the co-blowing agent n-pentane, add 5wt% of the mass of CO _{2 at the} experimental temperature and pressure, fill with CO _{2 to} replace air three times, and then program the autoclave for temperature control and heating. The rate is 10°C/min, heated to a foaming temperature of 110°C, after holding for half an hour, filled with high-pressure CO ₂ , the pressure is controlled to 15MPa, the blend is saturated for 2h, and then the pressure is quickly released. The pressure release rate is 500MPa/ s, to obtain a microcellular foam material.

Example 4

The blend was placed in an autoclave, filled with CO _{2 to} replace air three times, and then the autoclave was heated by programmed temperature control at a heating rate of 10°C/min, heated to a foaming temperature of 110°C, and after holding for half an hour, filled High-pressure CO ₂ , the pressure is controlled to 15 MPa, the blend is saturated for 2 hours, and then the pressure is quickly relieved at a pressure relief rate of 500 MPa/s to obtain a microcellular foam material.

Example 5

Put the polystyrene raw material and polydimethylsiloxane (with a molecular weight of 17000g/mol) into a Hacker mixer to blend, the content of polydimethylsiloxane is 1wt%, and the blending temperature is 170 ℃, the blending time is 15 minutes, the torque speed is 100 revolutions/min, and the blending obtains a polystyrene/polydimethylsiloxane blend.

Example 6

Place the polystyrene raw material in the autoclave, add the co-blowing agent absolute ethanol, add 5wt% of the CO ₂ mass under the experimental temperature and pressure, fill with CO _{2 to} replace the air three times, and then program the autoclave to control the temperature Heating at a heating rate of 10°C/min, heating to a foaming temperature of 110°C, after holding for half an hour, fill with high-pressure CO ₂ and control the pressure to 15MPa to saturate the blend for 2h, and then perform rapid pressure relief. It is 500MPa/s to obtain a microcellular foam material.

Example 7

Place the polystyrene raw material in the autoclave, add the co-blowing agent n-pentane, the addition amount is 5wt% of the CO ₂ mass under the experimental temperature and pressure, fill with CO _{2 to} replace the air three times, and then program the autoclave to control the temperature Heating at a heating rate of 10°C/min, heating to a foaming temperature of 110°C, after holding for half an hour, fill with high-pressure CO ₂ and control the pressure to 15MPa to saturate the blend for 2h, and then perform rapid pressure relief. It is 500MPa/s to obtain a microcellular foam material.

Comparative example 1

Place the polystyrene raw material in an autoclave, fill it with CO ₂ replacement air three times, and then heat the autoclave with programmed temperature control at a heating rate of 10°C/min, and heat to a foaming temperature of 110°C. After holding for half an hour, Fill in high-pressure CO ₂ , control the pressure to 15 MPa, saturate the blend for 2 hours, and then perform rapid pressure relief at a pressure relief rate of 500 MPa/s to obtain a microcellular foam material.

Comparative example 2

The polystyrene raw material and polyvinyl acetate (with a molecular weight of 17000g/mol) are put into a Hacker mixer and blended. The content of polyvinyl acetate is 1wt%, the blending temperature is 180°C, and the blending time is 10min, the torque speed is 100 revolutions/min, blending to obtain a polystyrene/polyvinyl acetate blend.

Comparative example 3

Place the polystyrene raw material in an autoclave, add the co-blowing agent acetone, the addition amount is 5wt% of the mass of CO _{2 at the} experimental temperature and pressure, fill with CO _{2 to} replace the air three times, and then program the autoclave to control temperature and heat. The heating rate is 10°C/min, and the foaming temperature is 110°C. After holding for half an hour, it is filled with high-pressure CO ₂ and the pressure is controlled to 15 MPa to saturate the blend for 2 hours, and then perform rapid pressure relief. The pressure relief rate is 500 MPa /s to obtain a microcellular foam material.

Comparative example 4

Place the polystyrene raw material in the autoclave, add the co-blowing agent absolute ethanol, add 10wt% of the mass of CO _{2 at the} experimental temperature and pressure, fill with CO _{2 to} replace air three times, and then program the autoclave to control the temperature Heating at a heating rate of 10°C/min, heating to a foaming temperature of 110°C, after holding for half an hour, fill with high-pressure CO ₂ and control the pressure to 15MPa to saturate the blend for 2h, and then perform rapid pressure relief. It is 500MPa/s to obtain a microcellular foam material.

Effect Example 1

Using an analytical balance with a density component, the cell density of the foamed products obtained in Examples 1 to 7 and Comparative Examples 1 to 4 was measured, and the expansion ratio was calculated. Use liquid nitrogen to quench the obtained foamed product, spray gold on the cross section, and use a scanning electron microscope to measure and analyze the cell structure. The cell density, expansion ratio, and cell diameter of the foamed products obtained in Examples 1 to 7 and Comparative Examples 1 to 4 are shown in Table 1. Figures 1 to 7 are cross-sectional electron microscopes of the foamed products obtained in Examples 1 to 7 respectively. Figures 8-11 are cross-sectional electron micrographs of the foamed products obtained in Comparative Examples 1 to 4, respectively.

Table 1

Claims

A preparation method of polystyrene foam material, characterized in that it comprises the following steps: blending polystyrene and polydimethylsiloxane to obtain a polystyrene/polydimethylsiloxane blend物; The polystyrene/polydimethylsiloxane blend can be foamed under supercritical CO 2 conditions; wherein, the polydimethylsiloxane number weight molecular weight is 2000g/mol~ 17000g/mol.
The preparation method according to claim 1, wherein the polydimethylsiloxane has a number molecular weight of 2000 g/mol to 6000 g/mol, preferably 2000 g/mol.
The preparation method of claim 1, wherein the content of the polydimethylsiloxane in the polystyrene/polydimethylsiloxane blend is 0.8 to 1.2 wt%, which is relatively It is preferably 1 wt%.
The preparation method of claim 1, wherein the polystyrene material is Yangzi BASF Petrochemical 158K general-purpose polystyrene.
The preparation method of claim 1, wherein the blending is carried out in a Hack internal mixer;

And/or, the blending temperature is 170-180°C, preferably 170°C;

And/or, the blending time is 15-20 min, preferably 15 min;

And/or, the rotor speed in the blending is 80-100 revolutions/min, preferably 100 revolutions/min;

And/or, the polystyrene/polydimethylsiloxane blend is a sheet.
The preparation method of claim 1, wherein the foaming under supercritical CO 2 conditions is carried out as follows: placing the polystyrene/polydimethylsiloxane blend in an autoclave Inside, filled with CO 2 to replace air three times; heated the autoclave to the foaming temperature, after holding for half an hour, filled with supercritical CO 2 to set the pressure to make the polystyrene/polydimethylsiloxane The blend is saturated; then the pressure is relieved to obtain a polystyrene foam material.
The preparation method according to claim 6, wherein the heating is programmed temperature heating, and the heating rate is 8-12°C/min, preferably 10°C/min;

And/or, the foaming temperature is 105-115°C, preferably 110°C;

And/or, the pressure of the supercritical CO 2 is 14-15 MPa, preferably 15 MPa;

And/or, the saturation time is 1 to 2 hours, preferably 2 hours;

And/or, the average rate of pressure relief is 500-600 MPa/s, preferably 500 MPa/s.
The preparation method of claim 1, wherein the preparation method of the polystyrene foam material further comprises: before the foaming under the supercritical CO 2 condition, spraying the polystyrene/polystyrene The step of adding a co-blowing agent to the dimethylsiloxane blend; the added amount of the co-blowing agent is 5-7wt% of the supercritical CO 2 under the foaming temperature and pressure, preferably 5wt %.
8. The preparation method of claim 8, wherein the co-blowing agent is absolute ethanol or n-pentane, wherein the purity of the n-pentane is >99.8%.
A preparation method of polystyrene foam material, characterized in that it comprises the following steps: after adding a co-blowing agent to polystyrene, foaming under supercritical CO 2 conditions is sufficient; the co-foaming The additive amount of the agent is 5-7 wt% of the supercritical CO 2 under the foaming temperature and pressure, preferably 5 wt%.
The preparation method of claim 10, wherein the co-blowing agent is absolute ethanol or n-pentane, wherein the purity of the n-pentane is >99.8%.
The preparation method of claim 10, wherein the foaming under supercritical CO 2 conditions is carried out as follows: placing the polystyrene and the foaming agent in an autoclave, and filling CO 2 replaces the air three times; the autoclave is heated to the foaming temperature, and after holding for half an hour, it is filled with supercritical CO 2 to set the pressure to saturate the polystyrene; then the pressure is released to obtain polystyrene foam泡材料.
The preparation method according to claim 12, wherein the heating is programmed temperature heating, and the heating rate is 8-12°C/min, preferably 10°C/min;

And/or, the foaming temperature is 105-115°C, preferably 110°C;

And/or, the pressure of the supercritical CO 2 is 14-15 MPa, preferably 15 MPa;

And/or, the saturation time is 1 to 2 hours, preferably 2 hours;

And/or, the average rate of pressure relief is 500-600 MPa/s, preferably 500 MPa/s.
A polystyrene/polydimethylsiloxane blend, which is characterized in that it is composed of the following components in mass fractions: 98.5-99.5wt% polystyrene and 0.5-1.5wt% polydimethylsiloxane Oxyane; The polydimethylsiloxane has a number molecular weight of 2000 g/mol to 17000 g/mol, preferably 2000 g/mol to 6000 g/mol, and more preferably 2000 g/mol.
A polystyrene foam material prepared by the preparation method of any one of claims 1-9 or the preparation method of any one of 10-13.