CN109135060B - Foamed heat-insulating material mainly based on polypropylene matrix and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of foaming materials, and particularly relates to a foaming heat-insulating material taking a polypropylene matrix as a main component and a preparation method thereof.

Description

A kind of foam heat insulation material based on polypropylene matrix and preparation method thereof

technical field

The invention belongs to the technical field of foaming materials, in particular to a foaming heat insulation material mainly based on polypropylene matrix and a preparation method thereof.

Background technique

Polymer foam materials have the advantages of light weight, strong shock load absorption capacity and heat and sound insulation capacity, and are widely used in automobiles, construction, packaging, catering and other fields.

Polypropylene (PP) has excellent physical and chemical properties such as low density, non-toxic and odorless, high temperature resistance, and corrosion resistance. Advantages in reusable and environmental protection. However, due to the structural characteristics of polypropylene, the foaming process is difficult. The key is the problem of low melt strength, which makes it difficult to maintain the gas in the system, which leads to the escape of gas in the system, forming open cells or cell collapse.

In this regard, at present, many producers add other polymer raw materials (such as low-density polyethylene, chlorinated polyethylene, etc.) to the polypropylene base material to foam together to achieve the purpose of increasing the melt strength of the pure polypropylene system. The chemical composition has changed, which can limit the use of the product in certain areas.

If you can better deal with the problem of low melt strength of pure polypropylene, you can use cheap ordinary polypropylene for direct foaming.

Contents of the invention

The technical problem to be solved by the present invention is: the melt strength of polypropylene is low during the foaming process, which easily leads to gas escaping in the system to form open cells or cell collapse. To solve this technical problem, the present invention provides a polypropylene Propylene-based foam insulation materials, calculated in parts by weight, include

Wherein, blowing agent is azodicarbonamide,

The nucleating agent is calcium carbonate, aluminum powder, talcum powder, etc.

Metal-organic gels based on tetrazole compounds are

Fully mix the solution of methyl tetrazole (the following formula, R is CH ₃ ) or n-octyl tetrazole (the following formula, R is C ₈ H ₁₇ ) and the heavy metal salt solution of acetic acid, and carry out the reaction system after fully standing. Filtration, drying and pulverization of the resulting filter cake to obtain metal organogels based on tetrazole compounds,

Other additives mainly include dispersants and anti-aging agents.

The present invention also provides a preparation method of the above-mentioned foamed heat insulating material mainly based on polypropylene matrix:

Mix the random polypropylene and metal organogel based on tetrazole compounds fully and add them to the internal mixer for pre-mixing, then add foaming agent, nucleating agent and other additives to continue mixing fully , take out the material in the internal mixer and carry out molding foaming,

Wherein, the random polypropylene and the metal organogel based on the tetrazole compound are mixed in a high mixer, the rotating speed is 60r/min, and the mixing time is 15 minutes.

During the early mixing, the temperature was 170°C, the mixing time was 8 minutes, and the screw speed of the internal mixer was 45r/min.

After adding foaming agent, nucleating agent and other additives and continuing to mix, the temperature is 170°C, the mixing time is 2 minutes, and the screw speed of the internal mixer is 40r/min.

When molding and foaming, the pressure is 5MPa, the temperature is 230°C, and the time is 10min.

The beneficial effect of the present application is that: specifically, metal organogel is a polymer finally formed by combining multiple nitrogen atoms on the tetrazole ring with heavy metal palladium ions as coordination points. Due to the coordination effect, metal ions can be fixed At specific positions in the gel polymer, further agglomeration between inorganic metals is avoided;

The applicant speculates that it may be because the metal ions have poor compatibility in the polypropylene organic matrix, which makes the heavy metal ions in the sheet tend to migrate to the surface of the polypropylene sheet, and the foam molding process In this process, the softening of the polypropylene substrate also strengthens this trend, so that the metal drives the gel polymer formed by cooperating with the tetrazole compound to gradually migrate to the surface of the polypropylene sheet, and finally a considerable part of the gel polymer Migrate and gather near the surface of the sheet. Due to the numerous ring structures in the gel polymer, the strength is ideal, which is equivalent to forming a relatively stable barrier near the surface of the sheet, reducing the impact of the foaming gas on the aggregation. The degree of breakthrough of the propylene melt should keep the bubbles generated by the decomposition of the blowing agent staying inside the melt as much as possible, so as to fully foam the polypropylene matrix.

Detailed ways

Example 1

A foam heat insulation material mainly based on polypropylene matrix, calculated by parts by weight, each component is

Wherein, the preparation method of the metal organogel based on n-octyl tetrazole is:

The n-octyl tetrazole of 30g is completely dissolved in 1L of N,N-dimethylformamide to obtain n-octyl tetrazole solution,

The palladium acetate of 28.3g is completely dissolved in the N of 1L, in the N-dimethylformamide, obtains palladium acetate solution,

Fully mix the above-mentioned n-octyl tetrazolium solution and the above-mentioned palladium acetate solution and let it stand still. At the same time, gel formation occurs. After the gel is fully formed, filter the reaction system, and dry the filtered gel at 70°C for 1 hour. , crushed to 100 mesh, and continued to dry fully at 70°C;

The preparation method of the foam insulation material in the present embodiment is:

According to the weight of each component, the random polypropylene and the metal organogel based on n-octyl tetrazole were fully mixed in a high mixer, the high mixer speed was 60r/min, and the mixing time was 15 minutes; the mixture Add it into the internal mixer and carry out preliminary mixing, the mixing temperature is 170 ℃, the mixing time is 8 minutes, and the screw speed of the internal mixer is 45r/min; The nucleating agent, dispersant, and antioxidant continue to mix for 2 minutes, the mixing temperature is 170°C, and the screw speed of the internal mixer is 40r/min; immediately take 30g of the material in the internal mixer for molding and foaming, and the molding foaming The pressure of the foam is 3.5 MPa, the temperature is 230° C., the molding time is 10 minutes, and the foamed sheet is obtained after cooling with the mold sufficiently.

Example 2

A foam heat insulation material mainly based on polypropylene matrix, calculated by parts by weight, each component is

Wherein, the preparation method of the metal organogel based on n-octyltetrazole is the same as in Example 1;

The preparation method of the foamed heat insulating material in this embodiment is also the same as that in Embodiment 1.

Example 3

The "metal organogel based on n-octyl tetrazole" in Example 1 was replaced by an equimolar metal organogel based on methyl tetrazole, and the rest of the components and preparation operations were the same as in Example 1.

Wherein, the preparation method of the metal organogel based on methyltetrazole is:

The methyl tetrazole of 13.85g is completely dissolved in 1L of N,N-dimethylformamide to obtain a methyl tetrazole solution,

The palladium acetate of 28.3g is completely dissolved in the N of 1L, in the N-dimethylformamide, obtains palladium acetate solution,

Fully mix the above-mentioned methyl tetrazolium solution and the above-mentioned palladium acetate solution and let it stand still, at the same time, gel formation occurs. After the gel is fully formed, the reaction system is filtered, and the filtered gel is dried at 70 ° C for 1 hour. Crush to 100 mesh, and continue to dry fully at 70°C.

Comparative Example 1

Compared with Example 1, no n-octyltetrazole-based metal organic gel was added, and the remaining components and preparation operations were the same as Example 1.

Comparative Example 2

The "metal organogel based on n-octyltetrazole" in Example 1 is replaced by low-density polyethylene of equal mass

(DFDA-1253NT, Dow), and all the other components and preparation operations are the same as in Example 1.

Comparative Example 3

The "n-octyl tetrazole-based metal organogel" in Example 1 was replaced with an equal mass of metal-free n-octyl tetrazole monomer powder, and the rest of the components and preparation operations were the same as in Example 1.

Comparative Example 4

The "metal organogel based on n-octyltetrazole" in Example 1 was replaced by polyethylene tetrazole particle powder (100 mesh) of equal mass without metal components, and the rest of the components and preparation operations were the same as in Example 1 .

The foam sheet of final gain in above each embodiment, comparative example is detected by same test standard, and test result is as shown in the table below:

Analyzed from the above table, comparative example 2 is similar to the raw material compounding means of "adding other polymers in the polypropylene base material" in the conventional technology to improve the melt strength of polypropylene, so as to retain the bubbles in the melt, But because the addition of composite resin is seldom, so effect is not obvious (relative to comparative example 1);

However, in Examples 1 to 3, metal organogels using the same amount of tetrazole compounds did not need to make major adjustments to the composition of the raw materials, but effectively suppressed the bubbles from overflowing the material melt, and the improvement range was significantly improved. It seems that Some changes have taken place in the whole polypropylene system;

On the other hand, in Comparative Example 3 and Comparative Example 4, only monomers or polymers containing corresponding ring structures are added, and metal elements are not involved. The dispersion compatibility of these simple monomers or polymers in the polypropylene matrix should be It is better, but in effect there is almost no improvement compared to the original existing formula (comparative example 1), which has also fully illustrated that the retention effect of the foaming gas in this scheme should be metal ions and tetrazole compounds Due to the synergistic effect after the coordination combination, there will be the speculation in the previous beneficial effect part.

Claims (10)

1. A foaming heat insulating material based on polypropylene matrix, characterized in that: calculated in parts by weight, said foaming heat insulating material comprises

2. The foaming insulation material based on polypropylene matrix as claimed in claim 1, characterized in that: the foaming agent is azodicarbonamide. 3. The foam heat insulation material based on polypropylene matrix as claimed in claim 1, characterized in that: said nucleating agent is calcium carbonate, aluminum powder or talcum powder. 4. The foaming insulation material based on polypropylene matrix as claimed in claim 1, characterized in that: the preparation method of the metal organic gel based on tetrazole compounds is as follows: Fully mix the solution of methyl tetrazole or n-octyl tetrazole with the heavy metal salt solution of acetic acid, filter the reaction system after fully standing, dry and pulverize the obtained filter cake, and obtain the tetrazole-based compound metal organogels. 5. The foam heat insulation material based on polypropylene matrix as claimed in claim 1, characterized in that: said other additives include dispersants and anti-aging agents. 6. A method for preparing a foamed heat insulating material based on a polypropylene matrix as claimed in any one of claims 1 to 5, characterized in that: the preparation method is as follows: After fully mixing the random polypropylene and the metal organic gel based on tetrazole compounds, they are added to the internal mixer for pre-mixing, and then added to the internal mixer including the The foaming agent, the nucleating agent and the other auxiliary agents continue to be fully mixed, and then the materials in the internal mixer are taken out and molded for foaming. 7. The method for preparing a foamed heat insulating material based on a polypropylene matrix as claimed in claim 6, characterized in that: the random polypropylene and the metal organic gel based on tetrazole compounds are at a high temperature Mix in a mixer, the rotating speed of the high mixer is 60r/min, and the mixing time is 15 minutes. 8. The method for preparing a foamed heat-insulating material based on polypropylene matrix as claimed in claim 6, characterized in that: in the early stage of mixing, the temperature is 170°C, and the mixing time is 8 minutes. The screw speed of the internal mixer was 45r/min. 9. The preparation method of the foaming insulation material based on polypropylene matrix as claimed in claim 6, characterized in that: after adding the foaming agent, the nucleating agent and the other auxiliary agents, continue During mixing, the temperature is 170° C., the mixing time is 2 minutes, and the screw speed of the internal mixer is 40 r/min. 10. The preparation method of the foamed heat insulation material based on polypropylene matrix as claimed in claim 6, characterized in that: when molding and foaming, the pressure is 5 MPa, the temperature is 230°C, and the time is 10 minutes.