Melamine compounds
The structural units of lignin are guaiacyl phenylpropane, syringyl phenylpropane, and p-hydroxyphenylpropane:
Lignin has been modified by hydroxymethylation. Its molecular structure is similar to cured three-dimensional network phenolic resin. Its bonding mechanism is similar to the m-methyl-white system. It is non-toxic and pollution-free, and the bonding strength is maintained after aging. It has the characteristics of high efficiency and can be used alone or in combination with silica black.
D. Triazine system
The triazine system is a one-component direct adhesive system that was gradually developed in the 1970s. Compared with organic cobalt salts, it has better aging resistance. It is simpler than the meta-methyl-white bonding system. It is not easy to bloom during rubber processing and is easy to disperse. It does not emit white smoke during processing and has good properties. Scorch safety. Used for bonding rubber to copper-plated steel wire and polyester cord, and can be used as an adhesive for manufacturing tires, hoses, seals, etc.
The chemical structure of triazine derivatives used as adhesive systems is as follows:
In the formula, X is an amino group, a hydroxyl group, or a halogen atom; Y is a chlorine atom or a sulfhydryl group; Z is an amino group. A representative one is 2-chloro-4-amino-6(m-hydroxyphenoxy)-1,3,5-s-triazine (SW). The structure of s-triazine is very similar to the benzene ring structure, and the molecules can form a conjugated structure; at the same time, the oxygen atom on the phenoxy group increases the electron cloud density on the benzene ring, and electrophiles on the surface of the rubber or metal can easily An electrophilic reaction occurs at the para position of the oxygen group, causing the rubber to bond to the copper-plated steel wire. In the triazine binding system, the dosage of sulfur is generally about 3 parts, and the triazine component must be added in the early stage of rubber mixing [20].
E. Other adhesive systems
a) Oxide
Calcium oxide is mainly used for fluorine rubber and can be directly bonded to metal. The general combination is: fluorine rubber 100, furnace carbon black 60, calcium hydroxide 6, magnesium oxide 3, calcium oxide 5. The metal surface should be sandblasted and dried before bonding.
Iron oxide is mainly used for the direct bonding of rubber and metal. For details, see Chapter 5. Section 2.6.2 and Chapter 2. Section 1.3.1 of Part 1 of this manual. Iron oxide can also be used for bonding between silicone rubber vulcanizates. Commonly used adhesive formulas are as follows: vinyl silicone rubber 100, fumed silica 35, ferric oxide 5, n-butyl borate 3, paste vulcanization Agent DCBP 3.
b) Monosulfonyl thiourea is a thiourea derivative with the general structural formula RSO2NHSNHC6H5 (R is an aryl or alkyl group). It can be used as an accelerator and adhesion promoter. It is composed of sulfamide sodium salt and It is produced by the reaction of phenyl thiocyanate. It is non-toxic and can be used in pharmaceutical preparations. It is mainly used for the direct bonding of nitrile rubber and metal.
c) BLE is not only an anti-aging agent, but also can be used for the direct bonding of sulfur-vulcanized nitrile rubber or chloroprene rubber and copper-plated steel wire. The bonding level is similar to that of the m-methyl-white system. It is invalid if the system is connected.
2.1. Meta-methyl-white system adhesive
In m-methyl-white adhesive system adhesives, adhesive A, adhesive RA and adhesive RH are “methylene donors” and release methylene during the vulcanization process; resorcinol, Adhesive RS, Adhesive RE and Adhesive RS-11 are “methylene acceptors”, which can react with the methylene released by the “methylene donor” during the vulcanization process. The molecular structures of adhesive RL, adhesive RH, adhesive SW and adhesive AB-30 contain both methylene donors and methylene acceptors.
Adhesive RP and Adhesive RP-L are impregnating agents for polyester cords and cords.
2.1.1. Resorcinol (R-80) and its mixtures
This product is a methylene acceptor and needs to be used in conjunction with 2.5 parts of binder A, binder RA resin and other methylene donors. This product should be put in before mixing, and the methylene donor should be added before mixing. Put it in at the end of the training. This product is easier to disperse in the rubber than pure resorcinol, reduces smoke, and becomes darker when exposed to air, but does not affect the adhesive performance.
HG/T 2188-1991 “Adhesives for Rubber RS” is suitable for resorcinol donor adhesives prepared by melting resorcin and stearic acid. The technical requirements for adhesive RS are shown in Table 1.8.1-27.
2.1.2, Adhesive RF
Chemical composition: Resorcinol formaldehyde precondensed resin
This product replaces resorcin and is used as an adhesion promoter between rubber and steel cords or fibers. The free phenol content is less than 1%, which can reduce sublimation and smoke, reduce the generation of pungent odors, and reduce the risk of Environmental pollution.
Vulcanized rubber shows better aging resistance than resorcinol, especially the H extraction after heat aging has been improved.
2.1.3, Binder RE
Chemical composition: Resorcinol acetaldehyde pre-condensed resin, also known as 6# resin, is mainly used as a methine acceptor for phenolic resin type adhesive systems; it can also be used alone as a tackifier for rubber compounds to improve Glue viscosity.
This product is produced by condensation of excess resorcinol and 40% acetaldehyde aqueous solution under acidic conditions and dehydration. This product is easily soluble in water and acetone, but insoluble in benzene, toluene and n-heptane. It is easily hygroscopic and should be stored in a dry and cool place. This product is a methylene acceptor and needs to be used in conjunction with 2.5 parts of binder A, binder RA resin and other methylene donors. This product should be put in before mixing, and the methylene donor should be added before mixing. Invest in the final exercise.
The combined use of binder RE and binder A can improve the heat aging resistance, dynamic fatigue resistance and moisture resistance of the m-methyl-white system.
HG/T 2189-1991 “Adhesives for Rubber RE” is applicable to�It has better dynamic performance than R-80; it has higher scorch safety than R-80, and the vulcanization time is longer, which can obtain better adhesion performance, higher hardness and dynamic modulus.
The dosage of SL-3020 resin for the nail bonding system is 1.5 to 2.0 parts, and the ratio to HMMM is 1:1.0 to 1.5. Too much HMMM will prolong the vulcanization time. Generally it should be added during the second stage of mixing.
Adhesives belonging to the m-methyl-white adhesive system also include:
The adhesive RA is a mixture of hexamethoxymethylmelamine and active fillers.
Binder RP, chemical name 2,6-bis(2,4-dihydroxybenzyl)-4-chlorophenol, white powder, melting point 180~200℃, molecular structure formula:
The adhesive RP-L is a copolymer of p-chlorophenol, resorcinol and formaldehyde, a brown liquid.
Binder SW, chemical name 2-amino-4-chloro-6-m-hydroxyphenoxytriazine, off-white or light yellow powder, relative density 1.28g/cm3, melting point 200°C, molecular structure formula:
2.2. Cobalt salt bonding system
Cobalt salt system adhesives are very sensitive to the type of accelerator. They are usually combined with sulfenamide accelerators and can produce a synergistic effect with the m-methyl-white system.
Among cobalt salt system adhesives, cobalt borate and cobalt neodecanoate have the best overall performance. In particular, cobalt borate also has good anti-aging effects.
The general dosage of cobalt salt system adhesive is 0.15 to 1.0 parts.
2.2.1. Cobalt naphthenate RC-N10
Also known as: cobalt naphthoate, cobalt petroleum acid, cobalt cyclohexanoate, cobalt hexahydrobenzoate
Structural formula:
In the formula, R is (CH)H or H.
General formula: (CnH2n-1COO)2Co, where n is about 7-18, CAS number: 61789-51-3.
Cobalt is a variable valence metal, which has the characteristics that the energy required for the migration of high and low ion valence states is similar and it is easier to detach from the carboxyl group of naphthenic acid. This product is mainly used as an adhesion promoter between rubber and copper-plated and galvanized steel wires.
22.2, Cobalt neodecanoate
Molecular formula: C9H19CO2CoCO2 CnH2n+1 (2≤n≤13), CAS number: 27253-31-2.
Direct adhesion promoter, dosage is 1 to 2 parts.
HG/T 4073-2008 “Cobalt Neodecanoate” is suitable for carboxylic acids based on cobalt neodecanoate produced by the saponification reaction of cobalt alkaline compounds and mixed carboxylic acids based on neodecanoic acid. Cobalt salt mixture product. Cobalt neodecanoate is divided into two types according to users’ different requirements for product testing items. Type A products are tested for softening point, and type B products are tested for final melting point.
2.2.3. Cobalt borate
Molecular formula: (CnH2n+1O3Co)3B (3≤n≤13), CAS number: 68457-13-6, relative density 1.1~1.4g/cm3.
General structural formula:
This product is an adhesion promoter for rubber and copper-plated and galvanized steel wires. It has the characteristics of strong adhesion, heat resistance, steam resistance, salt water resistance and metal corrosion resistance, good aging resistance and easy use. It is suitable for NR, BR, SBR and their combined rubbers. It is a direct adhesion promoter for radial tires, steel wire reinforced conveyor belts, steel wire braided or wound hoses and other rubber and metal composite products. Dosage: 0.8 to 1.0 parts.
HG/T 4072-2008 “Cobalt Borate” is suitable for cobalt salt mixtures prepared by saponification reaction of cobalt alkaline compounds and mixed carboxylic acids based on neocaic acid and then boration reaction. Cobalt borate is divided into two types according to the cobalt content. Type BCo23 represents a product with a cobalt content of 22.5±0.7, and type BCo16 represents a product with a cobalt content of 15.5±0.5.
Suppliers of cobalt borate include: Jiangyin Sanliang Chemical Co., Ltd., Zhenjiang Matt New Materials Chemical Co., Ltd., etc.
2.2.4, Cobalt stearate
The structural formula is:
Cobalt stearate (RC-S95) is produced by the neutralization reaction of cobaltous alkaline compounds and stearic acid. Molecular formula C36H70CoO4, relative molecular mass: 578.32, CAS number: 1002-88-6, red-purple particles, softening point 80~100℃.
Cobalt stearate can be used as a heat stabilizer for polyvinyl chloride, ceramic pigments, etc.; it can be used as an oxidation catalyst for organic substances in organic synthesis; it can also be used as an active drier for coatings; but it is mainly used for steel cords. A cobalt salt adhesion promoter for rubber.
Suppliers of cobalt stearate include: Jiangyin Sanliang Chemical Co., Ltd., Dalian Aibosi Chemical Co., Ltd., etc.
Cobalt salt system adhesives also include:
M cobalt salt (Co-MBT), turquoise powder, molecular structural formula:
Cobalt dibutyldithiocarbamate, yellow-green powder, molecular structure formula:
Cobalt resinate (RC-R9), brown flake.
2.3. Modified lignin
The structural units of lignin are guaiacyl phenylpropane, syringyl phenylpropane, and p-hydroxyphenylpropane. After modification by hydroxymethylation, its molecular structure is similar to a cured three-dimensional network phenolic resin. A non-toxic and harmless, new type of rubber adhesion promoter, which can be used alone or in combination with silica black. Lignin can also be used as a lightweight semi-reinforcing filler, inorganic filler activator, and synergistic flame retardant.
2.4. p-nitrosobenzene
Structural formula:
Molecular formula: C6H4ON2, molecular weight: 138, CAS number: 9003-34-3.
This product is an adhesion promoter for rubber, metal, and cotton fibers. It can also be used as an accelerator for low-temperature vulcanization CR and an activator for IIR. This product produces slight discoloration, is nearly odorless and will not bloom.
�, yellow-green powder, molecular structure formula:
Cobalt resinate (RC-R9), brown flake.
2.3. Modified lignin
The structural units of lignin are guaiacyl phenylpropane, syringyl phenylpropane, and p-hydroxyphenylpropane. After modification by hydroxymethylation, its molecular structure is similar to a cured three-dimensional network phenolic resin. A non-toxic and harmless, new type of rubber adhesion promoter, which can be used alone or in combination with silica black. Lignin can also be used as a lightweight semi-reinforcing filler, inorganic filler activator, and synergistic flame retardant.
2.4. p-nitrosobenzene
Structural formula:
Molecular formula: C6H4ON2, molecular weight: 138, CAS number: 9003-34-3.
This product is an adhesion promoter for rubber, metal, and cotton fibers. It can also be used as an accelerator for low-temperature vulcanization CR and an activator for IIR. This product produces slight discoloration, is nearly odorless and will not bloom.
