阅读说明：本技术 一种近熔化温度连续变压载压扩孔制备发泡材料的方法 (Method for preparing foaming material by near-melting temperature continuous variable-pressure-bearing reaming ) 是由 陈海贤 魏增 董梅 徐朝晖 于 2020-12-18 设计创作，主要内容包括：本发明公开了一种近熔化温度连续变压载压扩孔制备发泡材料的方法,以物理或者化学发泡初步制备较低发泡倍率的发泡材料,在其Tm温度(熔化温度)附近,通过变压连续载压,达到工艺要求后泄压扩孔,再连续进行二次变压连续载压,达到工艺要求后迅速泄压载压,此步骤可重复多次,直至发泡颗粒达到所需发泡倍率。该方法在同一个载压釜内完成,生产过程中温度始终在泡沫颗粒基材Tm温度±20℃范围波动,该方法大幅度降低了生产能耗、提高了载压效率,缩短了载压时间,同时还减少了多次装卸物料的操作流程,具有能耗低、效率高、省人工等特点,具有重大的经济和社会效益,特别适用于高发泡倍率高分子泡沫材料的制造。(The invention discloses a method for preparing a foaming material by near-melting temperature continuous pressure-changing and pressure-loading chambering, which is characterized in that the foaming material with lower foaming multiplying power is preliminarily prepared by physical or chemical foaming, the pressure is released and the chambering is carried out after the process requirements are met by the pressure-changing continuous pressure-loading near the Tm (melting temperature), the pressure is quickly released and the pressure is loaded after the process requirements are met, and the step can be repeated for many times until foaming particles reach the required foaming multiplying power. The method is completed in the same pressure-bearing kettle, the temperature always fluctuates within the range of +/-20 ℃ of the Tm temperature of the foam particle base material in the production process, the method greatly reduces the production energy consumption, improves the pressure-bearing efficiency, shortens the pressure-bearing time, simultaneously reduces the operation flow of loading and unloading materials for many times, has the characteristics of low energy consumption, high efficiency, labor saving and the like, has great economic and social benefits, and is particularly suitable for manufacturing high-foaming-ratio high-polymer foam materials.)

1. A method for preparing a foaming material by near-melting temperature continuous variable pressure loading and reaming is characterized by comprising the following steps of: the method comprises the following steps:

placing a primarily foamed foaming material into a pressure-bearing kettle, sealing the pressure-bearing kettle, heating the pressure-bearing kettle to a temperature slightly lower than the melting temperature Tm of the foaming material through an external heat source, and keeping the temperature in the pressure-bearing kettle stable;

step two, introducing a pressure-carrying gas into the pressure-carrying kettle, and controlling the pressure of the pressure-carrying gas in the pressure-carrying kettle according to the characteristics of the base material; the pressure of the pressure-carrying gas is changed continuously along with the change of the pressure-carrying time, and the pressure is increased gradually;

step three, after the set pressure is reached, the pressure of the pressure-carrying gas is stopped, and the pressure is maintained for 0-3 hours, so that the internal pressure of the foaming material is uniform;

opening a pressure relief hole of the pressure loading kettle, relieving the pressure to process pressure at a certain speed, expanding and reaming the foaming material in the pressure loading kettle, and finishing a pressure loading and reaming process;

and step five, requiring higher foaming ratio, closing the pressure relief hole after pressure relief is finished, repeating the steps one to four until the target foaming ratio is reached, and taking out the foaming material after cooling to obtain the product.

2. The method for preparing the foamed material by the continuous variable-pressure bearing and chambering at the near-melting temperature of claim 1, wherein the method comprises the following steps: the base material of the foaming material in the first step is LDPE, HDPE, LLDPE, EVA, PP, NBR, PVC, TPE, TPV, PS, PET, polyolefin thermoplastic elastomer TPO, TPU, but is not limited to one or a mixture of the above.

3. The method for preparing the foamed material by the continuous variable-pressure bearing and chambering at the near-melting temperature of claim 1, wherein the method comprises the following steps: the foaming material in the first step is a foaming material in various shapes of particles, sheets, bars, coiled materials and profiled bars.

4. The method for preparing the foamed material by the continuous variable-pressure bearing and chambering at the near-melting temperature of claim 1, wherein the method comprises the following steps: the temperature of the foaming particles in the first step is slightly lower than the melting temperature of the base material Tm, and the process operation temperature is 2-10 ℃ lower than the Tm temperature.

5. The method for preparing the foamed material by the continuous variable-pressure bearing and chambering at the near-melting temperature of claim 1, wherein the method comprises the following steps: the carrier gas in the second step comprises air, nitrogen, helium, volatile alkane and various gases or gasified liquids which are not reacted with the foaming material and can infiltrate into the foaming material.

6. The method for preparing the foamed material by the continuous variable-pressure bearing and chambering at the near-melting temperature of claim 1, wherein the method comprises the following steps: and the pressure of the load gas in the second step is accurately adjusted, and the adjustment range is 0.05 MPa-1 MPa.

7. The method for preparing the foamed material by the continuous variable-pressure bearing and chambering at the near-melting temperature of claim 1, wherein the method comprises the following steps: pressure of the pressurized gas in the second stepThe force varies according to the time curve according to the pressure P of the inner cavity of the foamed material₁The pressure of the pressure-carrying gas in the kettle is P₂，P₂And P₁The pressure difference of (A) is delta P, and the pressure range of delta P is 0.01 MPa-0.5 MPa.

8. The method for preparing the foamed material by the continuous variable-pressure bearing and chambering at the near-melting temperature of claim 1, wherein the method comprises the following steps: adding a release agent on the surface of the foaming material, wherein the release agent comprises one or more substances of organic or inorganic liquid and powder which play a role of interfacial isolation, such as water, talcum powder, calcium carbonate, a release agent and silicone oil.

Technical Field

Belongs to the field of polymer foaming, and particularly relates to a method for preparing a foaming material by near-melting temperature continuous pressure-changing, pressure-loading and hole-expanding.

Background

The foaming material has the advantages of light weight, sound insulation, heat insulation, high specific strength, low cost and the like, so the foaming material is widely applied to the fields of packaging industry, petrochemical industry, building industry, transportation industry, aerospace industry, automobile industry, sports industry and the like.

With the improvement of environmental protection requirements, more and more physical foaming technology is adopted for foaming, at present, the foaming particles are prepared firstly in common production, and then the required products are prepared by secondary forming of the foaming particles. The common reaming process at present comprises the following steps: and (3) feeding the foamed particles into a hole expanding kettle, heating to a certain temperature, introducing high-pressure compressed air, preserving heat and pressure for more than 10 hours, and rapidly relieving pressure after the compressed air is completely soaked to expand the holes to obtain the required product. The method is also applicable to parts of small-size profiles. Because the infiltration temperature is generally lower, the pressure loading time is longer, the pressure of the pressure loading gas is higher, the production efficiency is low, and the energy consumption is high.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for preparing a foaming material by continuous variable pressure bearing and hole expansion at a temperature close to a melting temperature.

The technical scheme adopted by the invention for solving the problems is as follows: a method for preparing a foaming material by near-melting temperature continuous variable-pressure bearing reaming comprises the following steps:

step one, placing the foamed material subjected to primary foaming into a pressure-bearing kettle. And (3) sealing the pressure-bearing kettle, heating the pressure-bearing kettle to a temperature (melting temperature) slightly lower than the Tm (melting temperature) of the foaming material through an external heat source, and keeping the temperature in the kettle stable.

Step two, introducing a pressure-carrying gas into the pressure-carrying kettle, and controlling the pressure of the pressure-carrying gas in the kettle according to the characteristics of the base material; the pressure of the pressure-carrying gas is changed continuously along with the change of the pressure-carrying time, and the pressure is increased gradually;

step three, after the set pressure is reached, the pressure of the pressure-carrying gas is stopped, and the pressure is maintained for 0-3 hours, so that the internal pressure of the foaming material is uniform;

and step four, opening a pressure relief hole of the pressure-bearing kettle, relieving the pressure to the process pressure at a certain speed, expanding and reaming the foaming material in the pressure-bearing kettle, and finishing the process of one-time pressure-bearing reaming.

And step five, requiring higher foaming ratio, closing the pressure relief hole after pressure relief is finished, repeating the steps one to four until the target foaming ratio is reached, and taking out the foaming material after cooling to obtain the product.

Further, the foamed material substrate in the first step is made of LDPE, HDPE, LLDPE, EVA, PP, NBR, PVC, TPE, TPV, PS, PET, polyolefin thermoplastic elastomer (TPO), TPU, etc., including but not limited to one or a mixture of the above.

Further, the foaming material in the first step may be a foaming material in various shapes such as particles, sheets, rods, rolls, profiles, and the like.

Furthermore, the temperature of the foaming particles in the first step is slightly lower than the Tm of the base material, and the preferable process operation temperature is 2-10 ℃ lower than the Tm temperature.

Further, the pressure-carrying gas in the second step may be various gases or gasified liquids, preferably air, which are unreactive with the foaming material and capable of infiltrating into the foaming material, such as air, nitrogen, helium, and volatile alkane.

Furthermore, the pressure of the carrier gas in the second step can be accurately adjusted, and the adjustment range is 0.05 MPa-1 MPa.

Furthermore, the pressure of the pressure-carrying gas in the step two is changed along with a time curve according to the condition that the pressure of the inner cavity of the foaming material is P₁The pressure of the pressure-carrying gas in the kettle is P₂，P₂And P₁The pressure difference of the pressure difference is delta P, the pressure range of the delta P is 0.01 MPa-0.5 MPa, preferably 0.01 MPa-0.3 MPa, the pressure can keep the continuous permeation and infiltration of the pressure-carrying gas, and the cell structure of the foaming material can not be damaged.

Further, in order to prevent the foaming material from being adhered due to inaccurate temperature control, a release agent, including but not limited to one or more of water, talcum powder, calcium carbonate, a release agent, organic or inorganic liquid with interface release function, powder and the like, can be added on the surface of the foaming material.

The invention has the beneficial effects that:

1. through the nearly Tm temperature of control pressure-carrying temperature at the foaming substrate, both guaranteed that foaming material has certain mechanical strength, the integrality of inside and outside structure has been guaranteed, can make the molecule chain segment creep easily relatively again, be favorable to the pressure-carrying gas can be fast enough soak foaming material inside, along with the change of time, the minute-pressure difference that lasts the increase is guaranteeing not to destroy under the condition of foaming material cell structure, can last soak inside foaming material with the highest efficiency, can shorten pressure-carrying infiltration time by a wide margin.

2. After the pressure-bearing infiltration is finished, the chambering and foaming can be directly carried out in the pressure-bearing kettle, and the continuous secondary and tertiary pressure-bearing chambering can be carried out, and the processes of temperature reduction and temperature rise are not needed, so that the energy consumption is low, the manual operation amount is less, and the product quality is stable.

Detailed Description

The present invention will be described in detail with reference to the following examples:

the invention fully utilizes the characteristics of the base material of the foaming material, and when the temperature is lower, molecular chains are difficult to creep, and the loaded gas is difficult to soak, and can only be slowly soaked in a high-pressure and long-time mode. When the temperature is too high, the strength of the foaming material is not enough, the original cell structure is damaged, and hole expansion cannot be carried out. The comprehensive optimization setting of the infiltration temperature enables the foam material to have certain mechanical strength, thereby being beneficial to infiltration of the pressure-carrying gas, and meanwhile, the skill ensures the rapid infiltration of the pressure-carrying gas by controlling the pressure difference inside and outside the foam material within a smaller range, and the original foam structure can not be damaged. And the continuous hole expanding process has no large temperature fluctuation and low energy consumption.

Example 1:

step one, selecting EPP foaming particles with the foaming ratio of 5 times, placing the EPP foaming particles in a pressure-bearing kettle, sealing the pressure-bearing kettle, heating the pressure-bearing kettle to 136 ℃ through an external heat source, and keeping the temperature in the kettle stable.

And step two, introducing compressed air into the pressure-bearing kettle, changing the ventilation pressure with time according to the process requirement, and keeping the pressure in the pressure-bearing kettle to be gradually increased from 0.05MPa to 0.4MPa for 2.5 hours.

Step three, after the pressure reaches 0.4MPa, the pressure of the pressure-carrying gas is stopped, and the pressure is maintained for 0.5 h;

and step four, opening a pressure relief hole of the pressure-bearing kettle, relieving the pressure at the pressure relief rate of 1MPa/s to normal pressure, expanding and reaming the foaming material in the pressure-bearing kettle, and finishing the one-time pressure-bearing and reaming process to prepare a first sample.

Example 2:

step one, putting a sample part produced in the embodiment into a pressure-loading kettle for secondary pressure loading, sealing the pressure-loading kettle, and keeping the temperature in the pressure-loading kettle to be 136 ℃ stable through an external heat source.

And step two, introducing compressed air into the pressure-bearing kettle, changing the ventilation pressure with time according to the process requirement, and keeping the pressure in the pressure-bearing kettle to be gradually increased from 0.05MPa to 0.3MPa for 1.5 h.

Step three, after the pressure reaches 0.3MPa, the pressure of the pressure-carrying gas is stopped, and the pressure is maintained for 0.5 h;

and step four, opening a pressure relief hole of the pressure-carrying kettle, relieving the pressure to normal pressure at the pressure relief rate of 1MPa/s, expanding the foaming material in the pressure-carrying kettle for the second time, and performing secondary pressure-carrying hole expansion to obtain a sample 2.

Example 3:

step one, selecting EPP foaming particles with the foaming ratio of 5 times, placing the EPP foaming particles in a pressure-bearing kettle, sealing the pressure-bearing kettle, heating the pressure-bearing kettle to 130 ℃ through an external heat source, and keeping the temperature in the kettle stable.

And step two, introducing compressed air into the pressure-bearing kettle, changing the ventilation pressure with time according to the process requirement, and keeping the pressure in the pressure-bearing kettle to be gradually increased from 0.05MPa to 0.4MPa for 4 hours.

Step three, after the pressure reaches 0.4MPa, the pressure of the pressure-carrying gas is stopped, and the pressure is maintained for 1 hour;

and step four, opening a pressure relief hole of the pressure-bearing kettle, relieving the pressure at the pressure relief rate of 1MPa/s to normal pressure, expanding and reaming the foaming material in the pressure-bearing kettle, and finishing the process of one-time pressure-bearing reaming to prepare a sample III.

Example 4:

step one, selecting TPU foaming particles with the foaming ratio of 6 times, placing the TPU foaming particles into a pressure-bearing kettle, sealing the pressure-bearing kettle, heating the pressure-bearing kettle to 165 ℃ through an external heat source, and keeping the temperature in the kettle stable.

And step two, introducing compressed air into the pressure-bearing kettle, changing the ventilation pressure with time according to the process requirement, keeping the pressure in the pressure-bearing kettle to be gradually increased from 0.05MPa to 0.3MPa, and increasing the pressure for 3 hours.

Step three, after the pressure reaches 0.3MPa, the pressure of the pressure-carrying gas is stopped, and the pressure is maintained for 1 hour;

and step four, opening a pressure relief hole of the pressure-bearing kettle, relieving the pressure at the pressure relief rate of 1MPa/s to normal pressure, expanding and reaming the foaming material in the pressure-bearing kettle, and finishing the process of one-time pressure-bearing reaming, thus obtaining a sample four.

Example 5:

selecting an EVA (ethylene-vinyl acetate) foaming sheet with a foaming ratio of 10 times, placing the EVA foaming sheet into a pressure-bearing kettle with the sheet size of 10cm multiplied by 10cn multiplied by 6mm, sealing the pressure-bearing kettle, heating the pressure-bearing kettle to 90 ℃ through an external heat source, and keeping the temperature in the kettle stable.

And step two, introducing compressed air into the pressure-bearing kettle, changing the ventilation pressure with time according to the process requirement, and keeping the pressure in the pressure-bearing kettle to be gradually increased from 0.05MPa to 0.2MPa for 1.5 h.

Step three, after the pressure reaches 0.2MPa, the pressure of the pressure-carrying gas is stopped, and the pressure is maintained for 0.5 h;

and step four, opening a pressure relief hole of the pressure-bearing kettle, relieving the pressure at the pressure relief rate of 2MPa/s to normal pressure, expanding and reaming the foaming material in the pressure-bearing kettle, and finishing the process of one-time pressure-bearing reaming to prepare a fifth sample.

Example 6:

step one, selecting EPP foaming particles with the foaming ratio of 5 times, placing the EPP foaming particles in a pressure-bearing kettle, sealing the pressure-bearing kettle, heating the pressure-bearing kettle to 136 ℃ through an external heat source, and keeping the temperature in the kettle stable.

And step two, introducing compressed air into the pressure-bearing kettle, changing the ventilation pressure with time according to the process requirement, and keeping the pressure in the pressure-bearing kettle to be gradually increased from 0.05MPa to 0.4MPa for 2.5 hours.

Step three, after the pressure reaches 0.4MPa, the pressure of the pressure-carrying gas is stopped, and the pressure is maintained for 0.5 h;

step four, opening a pressure relief hole of the pressure-bearing kettle, relieving the pressure to 0.1MPa at the pressure relief rate of 1MPa/s, expanding and reaming the foaming material in the pressure-bearing kettle to finish the process of one-time pressure-bearing reaming,

and step five, sealing the pressure-bearing kettle, introducing compressed air into the pressure-bearing kettle, changing the ventilation pressure along with time according to the process requirement, and keeping the pressure in the pressure-bearing kettle to be gradually increased from 0.11MPa to 0.3MPa for 1 h.

Step six, after the pressure reaches 0.3MPa, the pressure of the pressure-carrying gas is stopped, and the pressure is maintained for 0.5 h;

and step seven, opening a pressure relief hole of the pressure-bearing kettle, relieving the pressure at the pressure relief rate of 1MPa/s to normal pressure, expanding the foaming material in the pressure-bearing kettle for the second time, and performing secondary hole expansion to finish the process of secondary pressure-bearing hole expansion to prepare a sample 6.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.