The structural units of lignin are guaiacylbenzene propane, lilacylbenzene propane, and p-hydroxyphenyl propane.
Lignin is modified by hydroxymethylation, its molecular structure is similar to the cured three-dimensional reticulated phenolic resin, and its bonding mechanism is similar to that of the inter-methane-white system, which is non-toxic, non-polluting, and has high bonding strength retention after aging, and can be used alone or in combination with silica.
D、Triazine system
Triazine system is a single-component direct bonding system, is gradually developed in the 1970s. Compared with organic cobalt salts, has a better aging resistance than between – A – white bonding system is simple, not easy to spray frost during the processing of rubber, easy to disperse, no white smoke during processing, with good scorching security. It is used for bonding rubber with 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 bonding system is as follows.
X is an amino, hydroxyl and halogen atom, Y is a chlorine atom or a mercapto group, and Z is an amino group. A representative one is 2-chloro-4-amino-6(m-hydroxyphenoxy)-1,3,5 homotriazine (SW). The structure of homotriazine is very similar to that of benzene ring, and the molecule can form a conjugated structure; meanwhile, the oxygen atom on the phenoxy group makes the electron cloud density on the benzene ring increase, and the electrophilic reagents on the rubber or metal surface can easily react electrophilically at the pro-opposition of the phenoxy group, thus making the rubber bond with the copper-plated steel wire. The amount of sulfur yellow in the triazine bonding system is generally about 3 parts, and the triazine component should be added at the beginning of the rubber refining [20].
E, other bonding systems
(a) oxide
Calcium oxide, mainly used for fluorine rubber, can be directly bonded with metal, generally with: fluorine rubber 100, furnace method 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, see Part I, Chapter 5 of this manual. Section II.6.2 and Chapter II. Section I.3.1. Iron oxide can also be used for bonding between silicone rubber vulcanization rubber, commonly used adhesive formulations are as follows: vinyl silicone rubber 100, fumed silica 35, ferric oxide 5, n-butyl borate 3, paste vulcanizing agent DCBP 3.
(b) monosulfonyl thiourea, a thiourea derivative, structural formula RSO2NHSNHC6H5 (R for aryl or alkyl), can be used as accelerator and adhesion enhancer, room temperature from the reaction of thiamide sodium salt and thiocyanate phenyl ester, non-toxic, can be used in pharmaceutical preparations, mainly for direct adhesion of nitrile rubber and metal.
(c) BLE, both antioxidant, can also be used for sulfur yellow vulcanization of nitrile rubber or neoprene and copper-plated steel wire direct bonding, bonding level is similar to the inter-methane-white system, in the peroxide cross-linking system is not effective.
2.1, between – A – white system adhesive
Between – a – white bonding system adhesive, adhesive A, adhesive RA and adhesive RH, etc. for “methylene to give body”, in the vulcanization process to release methylene; resorcinol, adhesive RS, adhesive RE and adhesive RS-11, etc. for “methylene acceptor Resorcinol, binder RS, binder RE and binder RS-11 are “methylene acceptors”, which can react with the methylene released from the “methylene donor” during the vulcanization process to resinize. The molecular structures of binder RL, binder RH, binder SW and binder AB-30 contain both methylene donor and methylene acceptor.
Binder RP and binder RP-L are impregnating agents for polyester cordage and cordage.
2.1.1, Resorcinol (R-80) and its mixture
This product belongs to methylene acceptor, it needs to be used with 2.5 parts of binder A, binder RA resin and other methylene giving body, this product should be put in the front section of blending, and methylene giving body should be put in the final refining of blending. This product is easier to disperse than pure resorcinol in the rubber, reduce smoke, darken in the air, but does not affect the bonding performance.
HG/T 2188-1991 “Adhesive RS for rubber” applies to resorcinol and stearic acid eutectic resorcinol giving body adhesive. Adhesive RS technical requirements are shown in Table 1.8.1-27.
2.1.2、Adhesive RF
Chemical composition: resorcinol formaldehyde pre-condensation resin
This product replaces resorcinol, used as a rubber and steel cord or fiber bonding enhancer, free phenol content is less than 1%, can reduce the sublimation phenomenon and smoke, reduce the generation of irritating odor and reduce the pollution of the environment.
Vulcanized rubber shows better aging resistance than resorcinol, especially the H extraction after thermal aging has been improved.
2.1.3、Adhesive RE
Chemical composition: resorcinol acetal pre-condensation resin, also known as 6 # resin, mainly used as a phenolic resin type adhesive system of hypo-methyl acceptor; can also be used alone as a tackifier of adhesive to improve the adhesive viscosity.
This product is made by condensation of excess resorcinol and aqueous solution of acetaldehyde with 40% content under acidic condition and dehydration. It is soluble in water, acetone, insoluble in benzene, toluene, n-heptane, easy to absorb moisture, should be stored in a dry and cool place. It is a kind of methylene acceptor, need to be used with 2.5 parts of adhesive A, adhesive RA resin and other methylene giving body, this product should be put in the pre-mixing section, and the hypo-methyl giving body should be put in the mixing final refining.
Adhesive RE and adhesive A used together can improve the heat-resistant aging, dynamic fatigue resistance and moisture resistance of the inter-methane-white system.
HG/T 2189-1991 “rubber adhesive RE” applies to resorcinol and acetaldehyde condensation under acid-catalyzed conditions and the product adhesive RE, adhesive RE technical requirements are shown in Table 1.8.1-31.
2.1.4, adhesive RH
Chemical composition: resorcinol-hexamethyltetramine complex, molecular formula: C6H4(OH)2.(CH2)6N4, relative molecular mass: 250.31, decomposition temperature 120 ℃.
Structural formula.
Resorcinol complexed with hexamethylenetetramine aqueous solution at 50℃, filtered, washed and dried to obtain the finished product. This product is mainly used as hypo-methyl giving body of phenolic resin type bonding system; also can be used alone as adhesive hardening agent. It is slightly soluble in water, almost insoluble in organic solvents, and will undergo condensation reaction at 110-120℃, releasing amine to produce insoluble resin. This product can be used as single component or as methylene giving body pie and methylene accepting body, generally added below 90℃ in the late mixing rubber temperature.
HG/T 2190-1991 “Adhesive RH for rubber” applies to resorcinol complexed with hexamethylenetetramine product – adhesive RH, adhesive RH technology
2.1.5, rubber adhesive A (adhesive HMMM, mimosa resin)
Chemical name: hexamethoxymethyl methanamine, hexahydroxymethyl melamine hexamethyl ether, 2,4,6-tris[bis(methoxymethyl)amino]-1,3,5-triazine, 2,4,6-tris[bis(methoxymethyl)amino]-1,3,5-triazine hexamethoxymethyl methanamine.
Structural formula.
Molecular Formula: C15H30N6O6, Relative Molecular Mass, 390.4353, CAS No.: 3089-11-0, Density: 1.205-1.220g/cm3, Boiling Point: 487°C, Flash Point: 248.3°C, Vapor Pressure: 1.23E-09mmHg.
Adhesive A is made from melamine dissolved in aqueous formaldehyde solution to make hexahydroxymethyl nectarine, then condensed with methanol and separated by dehydration. This product is a kind of methylene giving body, it needs to be used with 2~5 parts of GLR-18, GLR-19, GLR-20, RE resin and other methylene acceptors, the methylene acceptors should be put in the front section of mixing, and this product should be put in the final refining of mixing. It is easy to disperse in the rubber material and has better processing performance than hexamethyltetramine.
HG/T 2191-1991 “Adhesive A for rubber” applies to the hexamethoxymethyltetramine type hypomethylene-giving body adhesive made by the hydroxymethylation and etherification of dense amine, the technical requirements of adhesive A for rubber are shown in Table 1.8.1-35.
Adhesive A (adhesive HMMM) suppliers see Table 1.8.1-36
2.1.6、Adhesive RC
This product is made of AB-30 (melamine resin as the parent by graft copolymerization and the reaction of complex compounds, both formaldehyde giving body and formaldehyde acceptor of the dual function) and inorganic or organic carrier mixed in a certain proportion. This product has the dual function of formaldehyde giving body and formaldehyde accepting body, and is an inter-methane-white bonding system, which is suitable for the bonding of rubber and various skeleton materials including galvanized steel wire, copper-plated steel wire, polyester, etc. It is also especially suitable for the bonding of fluorine rubber and canvas, nylon, aramid, and can be used with 10-15 parts of white carbon black, or 0.5 parts of cobalt salt.
Suppliers of adhesives RC see Table 1.8.1-37
2.1.7, melamine compounds
This product is a derivative of hexamethoxymethyl methanamine and polyphenol, is the adhesive A and polyphenol heating and melting, stirring discharge, cold to room temperature to get the wax-like body. It is suitable for the bonding of rubber and copper-plated steel wire, glass fiber, rayon, polyester and polyamide skeleton materials, especially for the bonding of fluorine rubber with canvas, nylon and aramid, the effect is more prominent. This product is easy to disperse in the rubber, can improve the plasticity of the rubber, low heat, do not pollute the rubber, aging with good adhesion retention; this product has a methylene acceptor and give the body double function, single-component use, and 10-15 parts of silica, such as with cobalt salt system, the bonding effect is better.
2.1.8, resorcinol and styrene and formaldehyde reaction products (SL-3020 resin)
Structural formula.
Where, R is hydrogen or aryl alkyl or styrene.
Since the temperature of rubber one-stage compounding can sometimes be as high as 160-180℃, resorcinol will produce significant smoke phenomenon at this temperature (R-80 starts to lose a lot of weight at 150℃), so usually, resorcinol is usually added in the second stage of compounding. Because SL-3020 resin is modified by pre-condensation, the starting weight loss temperature is close to 200℃, so SL-3020 resin can be added at one stage of mixing; SL-3020 resin has better dynamic performance compared with R-80; the scorch safety is higher than R-80, the vulcanization time is longer, and better bonding performance, higher hardness and dynamic modulus can be obtained.
The amount of SL-3020 resin used for intermethyl bonding system is 1.5~2.0 parts, and the ratio with HMMM is 1:1.0~1.5, too much HMMM will prolong the vulcanization time. Generally should be added in the second stage of mixing.
Belonging to the inter – A – white bonding system of adhesives and.
Adhesive RA, is a mixture of hexamethoxymethyl methanamine and active filler.
Adhesive RP, chemical name 2,6-bis (2,4-dihydroxyphenylmethyl) -4-chlorophenol, white powder, melting point 180-200 ℃, molecular structure formula.
Adhesive RP-L, copolymer of p-chlorophenol, resorcinol and formaldehyde, brown liquid.
Adhesive SW, chemical name 2-amino-4-chloro-6-m-hydroxyphenoxy triazine, off-white or light yellow powder, relative density 1.28g/cm3, melting point 200 ℃, molecular structure formula.
2.2, cobalt salt bonding system
Cobalt salt system adhesive is very sensitive to the type of promoter, usually with the secondary sulfonamide promoter, with the inter-methane-white system can produce a synergistic effect.
In the cobalt salt system adhesive, the best overall performance is cobalt borylate and cobalt new decanoate, especially cobalt borylate also has a good anti-aging effect.
Cobalt salt system adhesive general dosage of 0.15 ~ 1.0 copies.
2.2.1、Cobalt naphthenate RC-N10
Also known as: cobalt naphthalate, cobalt petroleum acid, cobalt cyclohexanoate, cobalt hexahydrobenzoic acid
Structural formula.
Wherein, R is (CH)H or H.
General formula: (CnH2n-1COO)2Co, n in the formula is about 7-18, CAS No.: 61789-51-3.
Cobalt is a metastable metal with the property that the energy required for the migration of ions in high and low valence states is similar and it is easier to detach from the carboxyl group of naphthenic acid. This product is mainly used as the adhesion enhancer of rubber and copper-plated and galvanized steel wire.
22.2、Cobalt neodecanoate
Molecular formula: C9H19CO2CoCO2 CnH2n+1 (2≤n≤13), CAS No.: 27253-31-2.
Direct bonding enhancer, the dosage is 1~2 parts.
HG/T 4073-2008 “cobalt neodecanoate” applies to the cobalt subcobalt basic compound and the mixed carboxylic acid with neonic acid as the main saponification reaction and the cobalt salt mixture of carboxylic acid products made from cobalt neodecanoate. Cobalt neodecanoate is divided into two types according to the different requirements of users for product testing items. Type A products measure the softening point and type B products measure the final melting point.
2.2.3、Cobalt borylate
Molecular formula: (CnH2n+1O3Co)3B (3≤n≤13), CAS No.: 68457-13-6, relative density 1.1~1.4g/cm3.
Structure general formula.
This product is a bonding accelerator for rubber and copper-plated and galvanized steel wire. It has the characteristics of strong adhesion, heat resistance, steam resistance, salt water resistance and prevention of metal corrosion, good anti-aging property and easy to use. It is suitable for NR, BR, SBR and other rubber, and is a direct bonding enhancer for radial tires, steel wire reinforced conveyor belts, steel wire braided or wound hoses and other rubber and metal composite products. The dosage is 0.8~1.0 parts.
HG/T 4072-2008 “cobalt borylation” applies to the cobalt salt mixture made by the saponification reaction of cobaltous alkaline compounds and mixed carboxylic acid mainly with new aoiic acid and then borylation reaction. Cobalt borylide is divided into two types according to the cobalt content. BCo23 type indicates products with cobalt content of 22.5±0.7, and BCo16 type indicates products with cobalt content of 15.5±0.5.
Other suppliers of cobalt borylide include: Jiangyin Sanliang Chemical Co.
2.2.4、Cobalt stearate
Structural formula is
Cobalt stearate (RC-S95) is produced by the neutralization reaction of cobaltous alkaline compound and stearic acid. Molecular formula C36H70CoO4, relative molecular mass: 578.32, CAS No.: 1002-88-6, red-purple particles, softening point 80~100℃.
Cobalt stearate can be used as heat stabilizer for PVC, ceramic pigments, etc.; used as oxidation catalyst for organic substances in organic synthesis; also used as active drying agent for paints; but mainly a cobalt salt bonding accelerator for steel cord and rubber bonding.
Other suppliers of cobalt stearate include: Jiangyin Sanliang Chemical Co.
Cobalt salt system adhesives also include.
M cobalt salt (Co-MBT), lime green powder, molecular structure formula
Dibutyldithiocarbamic acid cobalt, yellow-green powder, the molecular structure formula is
Cobalt resinate (RC-R9), brown flakes.
2.3、Modified lignin
The structural unit of lignin is guaiacylbenzene propane, lilacylbenzene propane, p-hydroxyphenyl propane, modified by hydroxymethylation, its molecular structure is similar to the cured three-dimensional network phenolic resin, is a non-toxic and harmless, new rubber adhesion enhancer, can be used alone, and can also be used with silica. Lignin can also be used as a light semi-reinforcing filler, a non-toxic
