CN110669248A

CN110669248A - PVA (polyvinyl alcohol) foam material and foaming method thereof

Info

Publication number: CN110669248A
Application number: CN201910998736.5A
Authority: CN
Inventors: 陈奕辉
Original assignee: Water Soluble Degradation Materials Co Ltd
Current assignee: Water Soluble Degradation Materials Co Ltd
Priority date: 2019-10-21
Filing date: 2019-10-21
Publication date: 2020-01-10
Also published as: CN111704741B; CN111704741A

Abstract

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.

Description

PVA (polyvinyl alcohol) foam material and foaming method thereof

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.

Example 1

First, three sets of raw materials were prepared according to the following table for the preparation of three sets of foaming samples:

then, three sets of foaming samples V20, V21, and V22 were prepared according to the following procedure: taking PVA resin and deionized water, stirring, putting the mixture into a water bath at 90 ℃ for 2h, adding a foaming agent into the mixture, and uniformly stirring. The temperature of the single-screw extruder is 80-100-.

The PVA resin has the solubility of W grade provided by SRJJ company; blowing agent 031DU40 powder was supplied by Akzo Nobel company; the single screw extruder is RM-200M from HARPO; JNB12 from GRANT applied in a water bath; the detection instrument used was C43 from MTS and JCM-6000plus from JEOL in the United states.

The inventors examined the solubility (% insolubility) of a PVA resin having a solubility of class W provided by SRJJ corporation by the following test methods: putting 25g of PVA resin into a 1L container, adding 400ml of water into the container, putting the container into a water bath at 90 ℃, stirring (500 revolutions per minute), pouring the PVA solution into a separating funnel after 30 minutes, centrifuging to obtain a lower layer solution and separating an upper layer solution after the solutions are layered, then washing with water, continuously repeating the liquid separation process for 2 times, collecting the upper layer insoluble part/lower layer solution, drying in an oven for 3-4 hours at 60 ℃, and calculating to obtain the solubility.

And (3) taking three times of PVA resin for detection, wherein the detection results of the three times of PVA resin raw materials are as follows:

the actual insolubility was measured to be 6.1% by weight on average, which is higher (1.5% by weight or not more than 1.8% by weight) than the claimed insoluble fraction of PVA.

The three sets of foamed samples V20, V21, and V22 obtained above were tested, and the test results are shown in the following table:

from the above table, V20 achieves the following technical effects:

1.1 light weight-density of not more than 0.25g/cm³And PVA control group (1.2-1.3 g/cm)³) Weight loss by about 80%;

1.2 thickness-thickness up to 25mm, not less than 20mm +.

1.3 size-size 250x250x23, not less than 200mm x200 mm.

1.4 compressive strength high-the compressive strength at 10% deformation is 259KPa, much greater than 50KPa, comparable to EPS.

1.6 solubility is good-all insoluble substances do not exceed 8 wt% of the foaming PVA, the product is easy to decompose and is environment-friendly.

In addition, the scanning results of V20, V21 and V22 are shown in fig. 1, and it can be seen that the internal structure of the scanning device contains a large number of regular holes.

The sample was subjected to the REACH Regulation (EC) No.1907/2006 test, both of which were in accordance with the Regulation, and the test was passed.

The PVA foaming agent used in the above-described embodiment is a multi-component compound which is difficult to reverse, and in addition, the PVA resin itself used contains some insoluble portions which can be regarded as inert components, so that, in the actual production process, it is possible to meet the demand of the product without adding additional inert components, as shown in fig. 2, and the amounts of the remaining substances of the PVA resin and the finished foam at different temperatures, and it can be seen that both the PVA resin and the PVA foam contain various unknown components which can be regarded as inert components.

Claims

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.