阅读说明：本技术 一种超临界发泡成核剂及其制备方法 (Supercritical foaming nucleating agent and preparation method thereof ) 是由 罗李华 于 2019-10-08 设计创作，主要内容包括：本发明涉及一种成核剂,特别涉及一种超临界发泡成核剂及其制备方法,属于泡沫塑料技术领域。一种超临界发泡成核剂,该超临界发泡成核剂是由如下重量份的组分混合而成：有机酸及其衍生物5-50份、无机酸及其衍生物0-50份、碳酸盐5-50份、聚合物20-100份、分散剂1-10份。该成核剂具有成核效果好、制得的发泡产品具有泡孔细腻均匀、表面无水纹无凹陷、无针孔、各批次产品颜色均一稳定的优点。(The invention relates to a nucleating agent, in particular to a supercritical foaming nucleating agent and a preparation method thereof, belonging to the technical field of foamed plastics. A supercritical foaming nucleating agent is prepared by mixing the following components in parts by weight: 5-50 parts of organic acid and derivatives thereof, 0-50 parts of inorganic acid and derivatives thereof, 5-50 parts of carbonate, 20-100 parts of polymer and 1-10 parts of dispersant. The nucleating agent has good nucleating effect, and the prepared foaming product has the advantages of fine and uniform foam holes, no water marks on the surface, no depressions, no pinholes, and uniform and stable color of products in each batch.)

1. The supercritical foaming nucleating agent is characterized by being prepared by mixing the following components in parts by weight:

5-50 parts of organic acid and derivatives thereof,

0-50 parts of inorganic acid and derivatives thereof,

5 to 50 portions of carbonate,

20-100 parts of polymer,

1-10 parts of a dispersing agent.

2. the supercritical foaming nucleating agent according to claim 1, characterized in that: the organic acid and the derivatives thereof are one or a mixture of more of citric acid, calcium citrate, calcium hydrogen citrate, sodium citrate, monosodium citrate, disodium citrate, potassium citrate, monopotassium citrate, dipotassium citrate, magnesium hydrogen citrate, lactic acid, sodium lactate, calcium lactate, magnesium lactate, potassium lactate, aluminum lactate, zinc lactate, oleic acid, zinc oleate, calcium oleate, zinc isooctanoate, Zinc Monomethacrylate (ZMA), zinc acrylate (ZDA), sodium acrylate, sodium monomethacrylate, Zinc Dimethacrylate (ZDMA), magnesium methacrylate (MgDMA), zinc benzoate or zinc p-methyl benzoate.

3. The supercritical foaming nucleating agent according to claim 1, characterized in that: the inorganic acid and the derivatives thereof are one or a mixture of more of ammonium sulfate, ammonium persulfate, ammonium chloride, sodium phosphate, sodium dihydrogen phosphate, calcium dihydrogen phosphate, magnesium hydrogen phosphate, sodium pyrophosphate, calcium pyrophosphate or aluminum potassium sulfate.

4. The supercritical foaming nucleating agent according to claim 1, characterized in that: the carbonate is one or more of sodium carbonate, sodium bicarbonate, calcium carbonate, calcium bicarbonate, magnesium carbonate, magnesium bicarbonate, zinc carbonate, basic zinc carbonate, potassium carbonate or potassium bicarbonate.

5. The supercritical foaming nucleating agent according to claim 1, characterized in that: the polymer is one or a mixture of more of PP (polypropylene), PE (polyethylene), LDPE (low density polyethylene), HDPE (high density polyethylene), PS (polystyrene), HIPS (impact resistant polystyrene), EVA (ethylene-vinyl acetate copolymer), EPDM (ethylene propylene diene monomer) or SBR (styrene butadiene rubber).

6. The supercritical foaming nucleating agent according to claim 1, characterized in that: the lubricant is one or more of stearic acid, zinc stearate, calcium stearate, PE wax (polyethylene wax), OPE wax (oxidized polyethylene wax), glyceryl monostearate, paraffin, PEG (polyethylene glycol) or erucamide or oleic acid.

7. The supercritical foaming nucleating agent according to claim 1, characterized in that the supercritical foaming nucleating agent is prepared by mixing the following components in parts by weight:

40-60 parts of sodium bicarbonate and/or sodium carbonate,

25-50 parts of disodium citrate,

0-10 parts of zinc dimethacrylate,

10-20 parts of sodium dihydrogen phosphate,

0-5 parts of ammonium sulfate,

2-4 parts of stearic acid,

2-4 parts of PE wax,

95-100 parts of LDPE.

8. A method for preparing the supercritical foaming nucleating agent according to claim 1, characterized by comprising the steps of: grinding organic acid and derivatives thereof, inorganic acid and derivatives thereof and carbonate in the raw materials into superfine powder with median particle size of 1-20 microns by jet milling, adding polymer and lubricant to pre-disperse the material in the superfine powder state, and banburying and granulating to obtain the supercritical foaming nucleating agent.

Technical Field

The invention relates to a nucleating agent, in particular to a supercritical foaming nucleating agent and a preparation method thereof, belonging to the technical field of foamed plastics.

background

The foam plastic refers to a special plastic product which takes polymer resin as a matrix and contains a large number of tiny cells inside. Because the cells are filled with gas, they can also be referred to as gas-filled composite plastics. Currently, both thermoplastics and thermosets can be made into foams. The foamed plastic prepared by the foaming process can reduce the density of the material, improve the specific strength of the material and reduce the usage amount of plastic products. In addition, the foam plastic has the advantages of light weight, heat preservation, heat insulation, sound insulation and the like, and is widely applied to various aspects of packaging, transportation, buildings and the like.

Different from the traditional chemical foaming, the supercritical foaming adopts inorganic gas or alkane as a foaming agent, the gas substance is liquefied to reach a supercritical state through high pressure and proper temperature rise, the foaming agent and the polymer are uniformly mixed through mechanical mixing and the super-strong permeability of the supercritical fluid, and then the system is instantaneously expanded through decompression to obtain a polymer foaming product.

At present, the supercritical foamed plastics generally used mainly include PUF (Polyurethane foam), EPS (Expandable polystyrene), EPE (Expandable Polyethylene), EPP (Expandable Polypropylene), EPO (Expandable Polyolefin resin), and the like.

in terms of the development and promotion of supercritical foaming, the use of fluoroalkanes having a damaging effect on the ozone layer and low-boiling-point alkanes having a risk of deflagration has been gradually reduced in recent years, and instead, supercritical carbon dioxide and supercritical nitrogen gas have been used. Due to the high diffusion speed of carbon dioxide and nitrogen in the polymer and the poor compatibility of the two foaming agents with the polymer (low solubility in the polymer), the two foaming agents are easy to separate out and generate during the molten polymerization, bubbles are generated to cause coarse and uneven cells inside a foamed product, the profile effect of the product is influenced, and the mechanical properties of the obtained product are greatly weakened.

In order to solve the problem of uneven cells in the foamed product, the industry scholars and related scientific researchers add a certain amount of nucleating agent into the polymer through an internal mixer before foaming so as to achieve the purposes of homogenizing the cells and improving the cell rate. The nucleating agents commonly used in the industry at present are mainly divided into two types, one type is the nucleating agent for adjusting crystalline phase and improving the crystallinity of polymer, and the nucleating agent is mainly sorbitol and derivatives thereof; the other nucleating agent is mainly heterogeneous nucleating inorganic filler (various calcium salts, magnesium salts, silicon salts, titanium salts, sodium salts, diatomite, bentonite, talcum powder, zeolite, kaolin, montmorillonite, carbon fibers, glass fibers, graphite and carbon nanotubes) or organic acid and derivatives thereof (citrate, oxalate and diacid salt). The mechanism of the nucleating agent or the foaming mechanism is mainly formed, nucleated, precipitated and grown in hot spots, related researchers pay more attention to polymer synthesis and modification research, and research on the mechanism of the related nucleating agent is less, so that the nucleating agent in the industry is single in variety, does not have a bright phase of too many novel nucleating agents, is poor in universality or general in nucleating effect, and finally, the research on synthesis and modification has to be carried out in a week.

Disclosure of Invention

The invention aims to provide a supercritical foaming nucleating agent which has the advantages of good nucleating effect, fine and uniform foam holes, no water marks on the surface, no depressions, no pinholes and uniform and stable color of products in each batch.

the technical scheme adopted by the invention for solving the technical problems is as follows:

A supercritical foaming nucleating agent is prepared by mixing the following components in parts by weight: 5-50 parts of organic acid and derivatives thereof,

0-50 parts of inorganic acid and derivatives thereof,

5 to 50 portions of carbonate,

20-100 parts of polymer,

1-10 parts of a dispersing agent.

Preferably, the organic acid and its derivatives are one or more of citric acid, calcium citrate, calcium hydrogen citrate, sodium citrate, monosodium citrate, disodium citrate, potassium citrate, monopotassium citrate, dipotassium citrate, magnesium hydrogen citrate, lactic acid, sodium lactate, calcium lactate, magnesium lactate, potassium lactate, aluminum lactate, zinc lactate, oleic acid, zinc oleate, calcium oleate, zinc isooctanoate, zinc monomethacrylate (ZMMA), zinc acrylate (ZDA), sodium acrylate, sodium monomethacrylate, Zinc Dimethacrylate (ZDMA), magnesium methacrylate (MgDMA), zinc benzoate, or zinc p-methylbenzoate.

Preferably, the inorganic acid and its derivative is one or more of ammonium sulfate, ammonium persulfate, ammonium chloride, sodium phosphate, sodium dihydrogen phosphate, calcium dihydrogen phosphate, magnesium hydrogen phosphate, sodium pyrophosphate, calcium pyrophosphate, and aluminum potassium sulfate.

preferably, the carbonate is one or more of sodium carbonate, sodium bicarbonate, calcium carbonate, calcium bicarbonate, magnesium carbonate, magnesium bicarbonate, zinc carbonate, zinc hydroxycarbonate, potassium carbonate or potassium bicarbonate.

Preferably, the polymer is one or more of PP (polypropylene), PE (polyethylene), LDPE (low density polyethylene), HDPE (high density polyethylene), PS (polystyrene), HIPS (impact polystyrene), EVA (ethylene-vinyl acetate copolymer), EPDM (ethylene-propylene-diene monomer rubber) or SBR (styrene-butadiene rubber).

Preferably, the lubricant is one or more of stearic acid, zinc stearate, calcium stearate, PE wax (polyethylene wax), OPE wax (oxidized polyethylene wax), glyceryl monostearate, paraffin, PEG (polyethylene glycol) or erucamide or oleic acid.

Preferably, the supercritical foaming nucleating agent is prepared by mixing the following components in parts by weight:

40-60 parts of sodium bicarbonate and/or sodium carbonate,

25-50 parts of disodium citrate,

0-10 parts of zinc dimethacrylate,

10-20 parts of sodium dihydrogen phosphate,

0-5 parts of ammonium sulfate,

2-4 parts of stearic acid,

2-4 parts of PE wax,

95-100 parts of LDPE.

A preparation method of the supercritical foaming nucleating agent comprises the following steps: grinding organic acid and derivatives thereof, inorganic acid and derivatives thereof and carbonate in the raw materials into superfine powder with median particle size of 1-20 microns by jet milling, adding polymer and lubricant to pre-disperse the material in the superfine powder state, and banburying and granulating to obtain the supercritical foaming nucleating agent.

Compared with the prior art, the invention has the following advantages or beneficial effects:

(1) According to the invention, organic acid or inorganic acid is compounded with carbonate, the surface of the carbonate is activated by acid in the acid-base reaction process to generate tiny nucleation hot spots, and carbon dioxide generated on the hot spots is used as an out-of-phase core to achieve the purpose of gas condensation.

(2) The invention pays attention to the acid-base degree of the introduced organic acid salt and inorganic acid salt, requires the comprehensive effect of the related acid salt to be weak acidity, and enables the related acid salt to play the role of an activation modifier in the polymer, thus greatly improving the compatibility, the dispersibility and the saturation of the supercritical fluid in the polymer, greatly improving the number of bubbles in unit volume and enabling the polymer to achieve the effect of microcellular foaming.

(3) According to the invention, carbonate is introduced into the formula of the nucleating agent, and the problems of foaming agent loss and foamed product size stability caused by rapid reduction of polymer melt strength due to advanced foaming and excessively rapid nucleation and foaming are prevented through simple reaction of gas generated when the carbonate meets acid at high temperature.

(4) The invention discloses a method for preparing a high-foaming product with higher multiplying power and smaller specific gravity by introducing acidic acrylate as a nucleating agent for the first time and utilizing the strong activation of the acrylate to realize the surface grafting modification of inorganic filler and polymer, thereby improving the reinforcing effect of the filler on the polymer, improving the melt strength of the polymer and enhancing the solubility of inorganic gas in the polymer.

(5) The invention reasonably screens out food-grade compounds as nucleating agent components, so that related supercritical foaming products can be used in the field of food contact.

(6) According to the invention, the nucleating agent is co-crushed, so that the mixing effect of the compound nucleating agent is improved, and the quality of the nucleating agent is more stable and superior.

(7) The invention improves the uniformity of the product by pre-dispersing the composite nucleating agent by the polymer, and prevents the reaction loss in the storage process of the acid-base mixture by the isolation action of the polymer on acid and base (the invention can also reduce the reaction loss by step feeding of acid and base).

(8) The invention adds a proper amount of lubricant and dispersant, can realize auxiliary coating of mixed acid and alkali while improving banburying and granulation processes, and prevents the advanced reaction of acid and alkali.

Detailed Description

The technical solution of the present invention will be further specifically described below by way of specific examples. It is to be understood that the practice of the invention is not limited to the following examples, and that any variations and/or modifications may be made thereto without departing from the scope of the invention.

In the present invention, all parts and percentages are by weight, unless otherwise specified, and the equipment and materials used are commercially available or commonly used in the art. The methods in the following examples are conventional in the art unless otherwise specified.