Chemical foaming agent (Engineering plastic products

Chemical blowing agent

Chemical blowing agent is also known as decomposable blowing agent. They can be uniformly dispersed in the resin, decomposed by heat, and can produce at least one gas. Can be divided into inorganic blowing agent and organic blowing agent two categories. Organic blowing agents are the main blowing agents used in plastics, mainly azo, nitroso and sulfonyl hydrazides. There are also some blowing agent components whose foaming gas is released through an endothermic reaction between the two components.

01

azodicarbonamide

Orange crystalline powder, relative molecular weight 116.1, relative density 1.65, fineness (200 mesh passage) ≥99.5%, moisture ≤0.1%, ash ≤0.1%. Soluble in alkali, insoluble in alcohol, gasoline, benzene, pyridine and other general organic solvents, difficult to dissolve in water. Decomposition temperature 190 ~ 205℃, non-flammable. The gas output is 200 ~ 300ml/g, mainly nitrogen, carbon monoxide and a small amount of carbon dioxide. The storage is stable at room temperature and has self-extinguishing, but it produces a large amount of gas when it is decomposed above 120 ° C and is prone to explosion in a closed container.

Application: Suitable for PE, PVC, PS, PP, ABS, etc. The decomposition products are non-toxic, odorless and non-polluting, and pure white foam can be prepared. The decomposition temperature of this product is high, and the bubbles produced are uniform and dense. Suitable for closed cell foam, atmospheric or pressurized foam, thick or thin foam and other foam products. Such as PVC and plasticized paste foam, polyolefin calendering and molding foam, foamed artificial leather and so on.

02

2,2 '-azodiisobutyronitrile

White crystalline powder, relative density 1.1, volatile 1%, methanol insoluble 0.1%, melting point >99℃. Soluble in methanol, ethanol, propanol, ether, petroleum ether and other organic solvents, insoluble in water. The decomposition temperature is 98 ~ 110℃, the nitrogen is released, and the gas output is 130 ~ 155ml/g. Slow decomposition at room temperature, 30℃ storage for several months after significant deterioration, so this product should be stored below 10℃.

Application: Especially suitable for PVC, also can be used in epoxy resin, PS, phenolic resin and rubber. Decomposition heat is low, about 125.6 ~ 167.5J/mol, so the use of up to 40% does not cause products to burn, can be made white products. This product has low decomposition temperature and can be used for ordinary PVC paste. The toxicity is high, which greatly limits its application. In recent years, its application as blowing agent has been gradually reduced, and it is mainly used as polymerization initiator.

03

Diisopropyl azodicarboxylate

Orange oily liquid, relative molecular mass 202, freezing point 2.4℃, boiling point 75.5℃(33.31Pa), when heated alone, still stable at 240℃. Heat stabilizers such as lead salts, organotin compounds, cadmium soap and zinc soap can be used to activate it and reduce the decomposition temperature. The gas output at 100 ~ 200℃ is 200 ~ 350ml/g. Soluble in common plasticizers.

Use: liquid blowing agent, suitable for PE, PP, PVC and so on. It is easy to disperse in plastics, the bubble structure is uniform and dense, the decomposition products are odorless, non-toxic, colorless, and non-polluting, and can produce foam with extremely light color. Closed-cell foam or open-cell foam can be prepared by adjusting the formula and processing conditions.

04

Barium azodicarboxylate

Bright yellow powder, relative molecular weight 253.37, relative density 1.67, decomposition temperature 240 ~ 250℃. Gas capacity 170 ~ 175ml/g, decomposition to produce nitrogen, carbon monoxide, carbon dioxide, barium carbonate, etc. Insoluble in common solvents.

Use: high temperature blowing agent. High decomposition temperature, good processing safety. Suitable for polymers with high softening points, especially PP. It also has good effect as a blowing agent for injection molding and extrusion molding of nylon resin. It can also be used for hard and semi-hard PVC, ABS, etc.

05

Diethyl azobarboxylate

A red, odorless oily liquid. Molecular weight 174.16. Decomposition temperature 110 ~ 120℃. Gas output 190ml/g. Soluble in plasticizer. Stable storage. No response to vulcanization accelerator. Sensitive to moisture and pH changes. Metal salts (Cu, Fe, Co, Pb, Al, Sn and other metals) facilitate decomposition.

Use: PVC and its copolymer, PE, polyester, epoxy resin, PS, rubber blowing agent. The dosage is 0.5 ~ 10%.

06

azo-aminobenzene

Yellowish brown crystal with special smell. Relative molecular weight 197.24. Melting point 96 ~ 98℃, decomposition temperature 150℃. Gas output 113ml/g. Stable storage. It is easy to crystallize from the surface of the product, decompose at a lower temperature in the acidic medium, and belongs to the polluting blowing agent.

Application: It can be used as blowing agent of PVC and its copolymer, PS, PE, phenolic resin, epoxy resin, raw rubber and rubber, silicone polymer. Dosage 0.1 ~ 5%.

07

N, N-dinitroso pentamethylene tetramine (blowing agent H)

Light yellow crystalline powder, odorless in itself, in the wet state has a formaldehyde smell. Molecular weight 186.18. Relative density: 1.45. Solubility (room temperature, g/100g solvent) : methyl ethyl ketone 1.6, pyridine 1.8, ethyl acetoacetate 2.6, acetonitrile 5.6, morpholine 2.0, 1-nitropropane 1.4, dimethylformamide 14.7. The solubility in water, ethanol, benzene, ether and acetone is about 1. Decomposition temperature 190 ~ 205℃ (in the air), 130 ~ 190℃ (in resin or using decomposition AIDS). Gas volume 260 ~ 270ml/g. The decomposition gas is mainly nitrogen, with a small amount of carbon monoxide and carbon dioxide. This product is flammable, and contact with acid or acid mist will quickly catch fire and burn, so it can not be stored together with these substances, and open flame should be strictly prohibited.

Uses: As a blowing agent used in PVC. Large gas volume, high foaming efficiency. The use of organic acids such as salicylic acid, adipic acid, phthalic acid or urea as foaming AIDS can reduce the decomposition temperature (usually adjusted at 90 ~ 130 ° C). The heat generated during decomposition is large, which is easy to cause the "core burning" of thick products, and the decomposition products have a foul odor. The odor can be eliminated by using urea. The amount of this product in PVC is about 7 ~ 15%.

08

N,N' -dimethyl-n,N' -dinitroso p-phthalamide

The active ingredient in commercial products is 70%. Yellow powder, relative molecular weight 250.21, relative density 1.2. The decomposition temperature in the air is 105℃, 90 ~ 105℃ in the resin, the gas output is 126ml/g, and the decomposition gas is mainly nitrogen. The pure product is explosive, sensitive to impact and friction, so the product is filled with inert filler to increase safety.

Use: Can be used as PVC blowing agent, especially suitable for PVC paste, without the use of foaming additives can make open and closed cell foam body. Decomposition heat is small, can be used for thick products, decomposition residue pollution-free, but in the plastic will spray frost.

09

Sulfonyl hydrazides - benzene sulfonyl hydrazides

Light yellow or white fine powder, relative molecular weight 172.20. The relative density is 1.43 ~ 1.48, and the melting point is 99℃. The decomposition temperature in the air is >95℃, and the decomposition temperature in plastics is 95 ~ 100℃. The gas output is 130ml/g, and the decomposition gas is mainly nitrogen, with a small amount of water vapor.

Application: Can be used for PVC, phenolic resin, polyester blowing agent. The decomposition process is accompanied by heat, which increases the internal temperature of the product, so it is best to mix with sodium bicarbonate. The sulfur compounds produced by the decomposition of this product have a bad smell.

10

p-toluenesulfonizide

White crystalline fine powder. Molecular mass 186. Relative density 1.40 ~ 1.42. Melting point 100 ~ 110℃. Soluble in alkali, soluble in methanol, ethanol, methyl ethyl ketone, slightly soluble in water, aldehyde, insoluble in benzene and toluene. The decomposition temperature is 100 ~ 110℃, nitrogen and a small amount of water are released, and the gas output is 110 ~ 125ml/g. Sulfonic acid is hydrolyzed in hot water and nitrogen is released. At normal temperature, there is no moisture absorption phenomenon, and its chemical properties are stable. This product is flammable substance, but will not catch fire in case of acid.

Usage: This product is a low temperature blowing agent, suitable for PVC and other plastics and rubber. The resulting gases and decomposition residues are non-toxic, odorless and non-polluting. The cell structure produced by this product is fine and uniform, the shrinkage rate of the product is small, the tearing strength is large, especially suitable for the manufacture of closed cell foam and sponge. This product can be used for PVC white foam body, but in this case the mold surface must be chrome plated. Due to the low decomposition temperature of this product, the temperature should be avoided during kneading processing (generally lower than 80 ° C) to prevent advance foaming. Foaming AIDS can be used without this product. This product cannot be used with blowing agent H, because the reaction of these two blowing agents produces a lot of heat, which can lead to the internal burning of the product. This product should not be used with lead salt, so as not to produce black lead sulfide precipitation.

11

4,4 '-diphenyl sulfonyl hydrazine oxide

White or light yellow crystalline powder. Molecular weight 358.39. The relative density is 1.52. The decomposition temperature is 140 ~ 160℃, nitrogen and water vapor are released, and the gas output is about 120ml/g. Soluble in cyclohexanone, ethylene glycol, ether, slightly soluble in ethanol and warm water, insoluble in benzene and gasoline.

Uses: This product is a very wide range of adaptability blowing agent, known as universal blowing agent. It can be used for PVC, PE, PP, ABS resin, etc., and can also be used as a blend of plastic and rubber and a foaming agent of various synthetic rubber. Although the structure contains ether bonds, it is very stable. The decomposition temperature in the resin is 120 ~ 140℃. Sodium bicarbonate can be used to activate it and reduce the decomposition temperature. The cell structure is fine and uniform, and the decomposition gas and residue are non-toxic, odorless and non-polluting products. Suitable for the manufacture of PE foamed wire and cable insulation materials, microporous PVC paste foam and other foam plastics. This product has high processing safety, and there is no risk of premature foaming within 100℃. However, this product releases water when decomposing foaming, so it is not suitable for water avoidance occasions.

12

3,3 '-disulfonyl hydrazine diphenyl sulfone

Grayish white powder. Relative molecular mass 406.45. The relative density is 1.60. The decomposition temperature in the air is 148 ° C, and the decomposition temperature in vinyl plastics is 135 ~ 145 ° C. Gas output 110ml/g. Non-toxic.

Usage: This product is mainly used as soft PVC blowing agent, can also be used for hard PVC and PE. The gas generated by decomposition during foaming has no odor and is non-toxic, but the residue is polluting and can make the product colored.

13

1, 3-phenyldisulfonyl hydrazine

The commercial form is a mixture of 50% of this product and 50% chlorinated paraffin, which is a paste containing grayish white fine particles, with a relative molecular weight of 266.29 and a relative density of 1.5. The decomposition temperature in the air is about 150 ° C, the decomposition temperature in plastics is 115 ~ 130 ° C, and the gas output is 300ml/g.

Usage: This product can be used as blowing agent for rubber and plastic, mainly used for rubber. High processing safety, the risk of early foaming is small. Alkaline substances reduce their decomposition temperature. The gas produced by decomposition is mainly nitrogen.

14

p-toluenesulfonamide

Fine white powder. Molecular weight 229.25. Soluble in dimethyl sulfoxide, dimethyl formamide, dimethyl acetamide, concentrated ammonium hydroxide and alkaline water, insoluble in acetic acid, acetone, carbon tetrachloride, ethylene glycol, isopropyl alcohol, petroleum ether, toluene and water. The decomposition temperature in the air is 230 ° C, and the decomposition temperature in plastics is 213 ~ 225 ° C. The gases emitted are mainly nitrogen and carbon dioxide (about 2:1). The solid residues after decomposition are mainly p-xylene disulfide and p-toluenesulfonate, the former soluble in benzene and the latter soluble in water. This product has good storage stability at room temperature, but it should be avoided near steam pipes, fire sources and direct sunlight.

Use: This product is a high temperature nitrogen blowing agent, especially suitable for high temperature processing of plastics, such as ABS resin, nylon, hard PVC, HDPE, PP, PC, etc. Good processing safety, no risk of advance foaming. This product can also be used for natural rubber and synthetic rubber foam.

15

4,4 '-oxobide

This product is a high temperature blowing agent, the decomposition temperature is 210 ~ 220℃, the gas volume is about 145ml/g. The gases emitted are mainly nitrogen and carbon dioxide.

Application: Suitable for hard PVC, HDPE, high softening point PP, PC, ABS resin and other plastics with high processing temperature.

16

Trihydrazyl triazine

White or off-white powder. Molecular weight 171.61. Decomposition temperature 235 ~ 275℃. The gas volume is about 247ml/g. The gases emitted are mainly nitrogen and carbon dioxide.

Usage: This product is a high temperature blowing agent, suitable for hard and semi-hard PVC, PP, PC, ABS resin, polyamide and other plastics with high processing temperature. Good processing safety.

17

5-phenyltetrazole

A liquid substance. The relative density is 1.105 (50℃).

Usage: This product is a high temperature blowing agent, suitable for PC, polyamide and other polymers with high melting temperature.

18

Polysiloxane-polyalkoxy ether copolymer

Yellow or brownish yellow oily thick transparent liquid. Acid value <0.2mgKOH/g. The relative density is 1.04 ~ 1.08. Viscosity 0.15 ~ 0.5Pa· s (50℃).