阅读说明：本技术 一种pva发泡材料及其发泡方法 (PVA (polyvinyl alcohol) foam material and foaming method thereof ) 是由 陈奕辉 于 2019-10-21 设计创作，主要内容包括：一种PVA发泡材料及其发泡方法,本发明涉及一种发泡材料,为提供现有的PVA连续挤出发泡的难点,本发明利用PVA具有水解性的特点,将PVA在水解溶胀状态下进行以低于PVA沸点的温度进行发泡。本发明的有益效果在于：用水作为媒介在溶胀状态下加入微孔膨胀发泡剂,在PVA沸点以下发泡,既避免了PVA气化,又实现了挤出成型,操作过程简单；制备的成品重量轻(密度小),抗压强度高(高达259KPa),可降解成分高,环境友好。(The invention discloses a PVA foam material and a foaming method thereof, relates to a foam material, and aims to provide the difficulty of the existing continuous extrusion foaming of PVA. The invention has the beneficial effects that: the microporous expansion foaming agent is added in a swelling state by using water as a medium, and foaming is carried out below the boiling point of PVA, so that not only is PVA gasification avoided, but also extrusion molding is realized, and the operation process is simple; the prepared finished product has light weight (low density), high compressive strength (as high as 259KPa), high degradable components and environmental friendliness.)

1. A PVA foaming method is characterized in that a foaming agent is added into a PVA resin in a swelling state by taking water as a medium, and foaming is carried out at a temperature lower than the boiling point of the PVA.

2. The PVA foaming method of claim 1, wherein the foaming agent is 031DU40 foaming agent, 461DU40 foaming agent, 461DU20 foaming agent or 053DU40 foaming agent.

3. The PVA foaming method of claim 1, wherein the water level is deionized water.

4. The PVA foaming process of claim 1, wherein the blowing agent is present in an amount of 5% by weight of the resin.

5. The PVA foaming method according to claim 1, wherein the PVA resin and water are stirred and mixed and then subjected to a water bath at 80 to 95 ℃ to be in a swollen state.

6. The PVA foaming method of claim 1, wherein the foaming process comprises pre-foaming and secondary foaming, and the pre-foaming process comprises the following steps: adding a mixture of PVA resin, water and a foaming agent into a single-screw extruder, wherein the pre-foaming temperature is lower than the boiling point of PVA, and the screw rotating speed is 80-120 rpm; the secondary foaming process is as follows: and putting the pre-foamed product into a mold, putting the mold into a hot press, carrying out hot pressing at a temperature lower than the boiling point of the PVA, and putting the mold into an oven for baking after the hot pressing is finished, wherein the temperature of the oven is also lower than the boiling point of the PVA.

7. The PVA foaming method of claim 6, wherein the temperature of the single-screw extruder in the pre-foaming is 80-100-105-110 ℃.

8. The PVA foaming method of claim 6, wherein the hot pressing temperature of the hot press in the secondary foaming is 100 ℃ and the oven temperature is 60 ℃.

9. The PVA foaming method of claim 1, wherein the weight ratio of PVA resin to water is 10: 7.

10. A PVA foamed material, characterized in that it is prepared by a foaming process according to any one of claims 1 to 9.

Technical Field

The invention relates to a foaming material, in particular to a PVA foaming material and a foaming method thereof.

Background

Foamed polyvinyl alcohol (PVA) is an environment-friendly foamed plastic, and the traditional foamed plastic can cause environmental pollution in the using process due to the fact that the traditional foamed plastic cannot be degraded, and is definitely specified and forbidden to be used in some fields. The foamed PVA is a high polymer material which can be biodegraded in a natural environment, and the PVA contains hydroxyl and an open pore structure, so that the foamed PVA has excellent water absorption performance, is hard and high in strength in a dry state, has good flexibility in a wet state, and is widely applied to various fields. The preparation of PVA foam mainly comprises extrusion molding and compression molding, and the foaming methods generally comprise a chemical foaming method, a physical foaming method and a mechanical foaming method. The disadvantages of compression molding are high production cost, complex process and long cycle time, and the difficulty of thermoplastic molding is a difficulty in realizing continuous extrusion foaming molding because the melting point and the boiling point of the PVA material are very close, because the traditional foaming process of introducing gas in a molten state has the processing temperature of 20-30 ℃ or higher above the melting point, and is not suitable for PVA, and the PVA is easily gasified at the high temperature.

Disclosure of Invention

Therefore, how to overcome the above-mentioned problems and provide a new foaming method is the problem to be solved by the present invention, and to solve the technical problem, the present invention utilizes the characteristic of hydrolysis of PVA to foam PVA in a hydrolytic swelling state.

An object of the present invention is to provide a method for foaming a PVA resin at a boiling point or lower by adding a microcellular expansion blowing agent to the PVA resin in a swollen state using water as a medium.

The specific method comprises the following steps: stirring PVA resin and deionized water in a weight ratio of 10:7, putting the mixture into a water bath at 80-95 ℃ (90 ℃) for 2 hours, adding a foaming agent (031DU40 powder) accounting for 5-10% (preferably 5 wt%) of the weight of the PVA resin into the mixture, and uniformly stirring. The temperature of the single-screw extruder is 80-100-.

The blowing agent may be 031DU40 blowing agent, 461DU40 blowing agent, 461DU20 blowing agent, 053DU40 blowing agent supplied by Akzo Nobel company.

The invention has the beneficial effects that: the microporous expansion foaming agent is added in a swelling state by using water as a medium, and foaming is carried out below the boiling point of PVA, so that not only is PVA gasification avoided, but also extrusion molding is realized, and the operation process is simple; the prepared finished product has light weight (low density), high compressive strength (as high as 259KPa), high degradable components and environmental friendliness.

Drawings

FIG. 1 is an SEM image of PVA foam samples V20, V21, and V22.

FIG. 2 is a graph showing changes in the composition of PVA resin and PVA foam at different temperatures.

Detailed Description

For further explanation and explanation of the present invention, the following description is provided for further explanation and explanation of the present invention with reference to specific examples.