| Name | Vulcanizator |
| Synonyms | Vulcanizator |
| Use | Use in rubber can reduce the plasticity of raw rubber, increase the elasticity and strength, and can resist solvents and chemicals |
Rubber vulcanizing agent
vulcanizing agent refers to a kind of chemical substance that can make rubber molecular chain cross-chain reaction. It belongs to a kind of cross-linking agent and is also called bridge agent in industry. Since C.Goodyear discovered in 1839 that the use of sulfur can cross-link rubber, sulfur or sulfide has been used as a cross-linking agent in the rubber industry. This process is called vulcanization. Sulfur and sulfides are called vulcanizing agents. Later, it was discovered that in addition to sulfur and sulfides, other organic peroxides, quinones, metal oxides, amine compounds, resins, selenium, tellurium, quinone oxime compounds, etc., can make linear rubber molecules Cross-link to form a reticulated three-dimensional structure. Therefore, the term vulcanizing agent is not limited to sulfides, but generally refers to the cross-linking of rubber molecular chains, so that linear molecules form a three-dimensional, substances with increased elasticity and strength are called vulcanizing agents, and the term vulcanization should also have a corresponding meaning. In addition to some thermoplastic rubber does not need to be vulcanized, natural rubber and various synthetic rubber need to be vulcanized with vulcanizing agent, which greatly improves a series of physical and mechanical properties of rubber.
classification
At present, there are about dozens of vulcanizing agents produced as commodities, which can be divided into the following categories according to their chemical structure:
(1) elemental sulfur vulcanizing agent. The typical representative is sulfur, which is the most important and basic vulcanizing agent. The system of ordinary sulfur-accelerator-activator is used, which dominates the tire industry. Insoluble sulfur, used in non-frost products;
(2) Sulfur donor vulcanizing agent. The main varieties are the disulfide or tetrasulfide of Tyuram (accelerator TT, TMTT, TETD, etc.) and dithiomorpholine (vulcanizing agent DTDM), etc.;
(3) Peroxide vulcanizing agent. Not only used to vulcanize saturated rubber, but also some unsaturated rubber. There are dicumyl benzene and di-tert-butyl peroxide (vulcanizing agent DCP, DTBP), etc.;
(4) quinone vulcanizing agent. Mainly include p-quinone dioxime, dibenzoyl p-quinone dioxime (vulcanizing agent DBQD), etc. Mainly used for vulcanization of butyl rubber;
(5) polyamine vulcanizing agents. Mainly include triethylenetetramine, tetraethylenepentamine (vulcanizing agent TETA, TEPA), etc. Used for vulcanization of acrylate rubber and fluororubber. Metal oxide needs to be added when using;
(6) Resin vulcanizing agent. Such as p-tert-butyl phenol formaldehyde resin, p-tert-octyl phenol formaldehyde resin (vulcanizing agent 2402, 2502 resin). Mainly used in butyl rubber;
(7) Metal oxide. Commonly used metal oxides are zinc oxide, magnesium oxide, lead monoxide, and lead tetroxide. Mainly used in neoprene, chlorol rubber, polysulfide rubber, etc. Zinc oxide, magnesium oxide, etc. are usually used as active agents, but they can be used as vulcanizing agents in chloroprene, butyl chloride, carboxyl rubber and other adhesives.
In addition to the above vulcanizing agents, there have also been urethane, maleimide, isopropyl titanate vulcanizing agents recently.
The role and use of vulcanizing agent
In natural rubber, the combination of vulcanizing agent and sulfur can prevent vulcanization from returning to the original, improve heat resistance, reduce heat generation, resist aging, and improve the adhesion force between rubber and cord and the modulus of vulcanized rubber. Used in load tire shoulder rubber, buffer layer and other rubber, can solve the problem of skew load tire shoulder empty, can also be used for large size thick products of natural rubber and various rubber miscellaneous products. For example: combined with sulfur, accelerator MPMCZ or TMTD, vulcanized diene rubber (natural rubber, styrene butadiene rubber, butadiene rubber, synthetic isoprene rubber) has the advantages of prolonging scorching time, reducing calorific value, high constant elongation strength, excellent vulcanization reversion resistance, etc. At the same time, it can also increase H extraction, suitable for high temperature vulcanization of rubber (183 ℃), the dosage is 2-3phr.
Organic peroxides are especially suitable for saturated and low unsaturated polymer polymers because they cannot be crosslinked with sulfur. Compared with sulfur, its advantages are short vulcanization time, good heat resistance of vulcanized rubber, no corrosion, no pollution, can be used for transparent products, small permanent deformation of vulcanized rubber, and wide application range; the disadvantage is the tear strength Low, low elongation, some other additives have the effect of hindering vulcanization, not suitable for heating air vulcanization, smelly, easy to catch fire, and high price. There are five main types of organic peroxides: hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxy esters, and ketone peroxides.
As a vulcanization accelerator of neoprene, it can obviously improve the scorch resistance of the compound, and is suitable for processing neoprene in the high temperature season in the south.
the role of several common vulcanizing agents
resins are mainly used for butyl rubber. Commonly used are phenol formaldehyde derivatives.
amine compounds are mostly used in fluororubber and acrylate rubber. Mainly include: triethylene tetramine, tetraethylene pentamine, hexamethylene diamine, 3,3 & prime;-dichlorobenzidine and triisopropanolamine, etc.
ester compounds can be used as vulcanizing agents for butyl rubber, natural rubber and styrene butadiene rubber. It is characterized by easy dispersion, fast vulcanization speed, good ozone resistance and heat resistance of vulcanized rubber; the disadvantage is that it is easy to scorch. Commonly used are p-quinone dioxime, 4,4 & prime;-dibenzoylbenzoquinone dioxime, tetrachlorobenzenoquinone, polyp-nitroso benzoquinone, hydroquinone diethoxy ether, etc.
The vulcanizing agent is used as the vulcanizing agent for the peroxidation vulcanization of various rubbers, especially in the peroxide vulcanization process of Ding Qing rubber, ethylene propylene rubber and rubber blends, which can play a role in low compression deformation, fast vulcanization speed and heat-resistant air aging. For example, in NBR, when the dosage is 1.5phr, the permanent compression deformation is only 3-8%, which cannot be achieved with other vulcanizing agents.
When the anti-scorch agent is used in chlorosulfonated polyethylene rubber, it can be used as an anti-scorch agent in combination with magnesium oxide, pentaerythritol and double pentamethyl tetrasulfide (TRA); improve the compression deformation and calcium hydroxide And diphenylethylenediamine to form a maleimide vulcanization system with an dosage of 2-4phr, which can greatly reduce compression set and improve temperature resistance. Improve the bonding strength Improve the bonding strength of rubber and polyamide fabric, rubber and metal, suitable for direct bonding system.
sulfur-free vulcanizing agent is used for cable rubber. it can replace all sulfur-containing vulcanizing agents such as thiazole and qiuram, and solve the problem of copper conductor and copper electrical appliance blackening due to contact with sulfur-containing vulcanizing agent.
dosage
used as anti-scorch agent: 0.5-1.0phr used as vulcanizing agent: 2-3phr
To improve compression deformation: 1.5phr to improve adhesion strength: 0.5-5.0phr