Hot Vulcanized Bonding of Rubber to Metal

Hot Vulcanized Bonding of Rubber to Metal
Influence of rubber type
Degree of unsaturation:
Rubber with a high degree of unsaturation and high polarity bonds easily
Adhesion Index:

Non-Diolefin Elastomer:
Sulfur-free, non-accelerator vulcanization (e.g. peroxide vulcanization), containing high specific surface area fillers easy to bond;
Contains plasticizers, softening oils, waxes, etc., which are detrimental to bonding.
Elastomer mixtures: elastomer mixtures are not mutually soluble, but an elastomer in a continuous phase or dispersed phase distributed in another elastomer, resulting in a mixture of elastomers in one of the easier to vulcanize, the results of the bonding shadow has a great impact.
For example: NBR + NR hybrid elastomers are harder to bond than NBR.
Influence of vulcanization system
Vulcanizing agent:

Generally, rubber with higher sulfur content is easier to bond.
Bonding of elastomers with different vulcanization systems:
Conventional vulcanization systems are better than semi-cured systems;
Semi-cure system is better than effective cure system (low sulfur high promotion cure system);
Sulfur vulcanization is better than other vulcanization systems, such as peroxide vulcanization system, bisphenol A vulcanization system, amine vulcanization system, etc..
(Silent insertion: consider a good vulcanization system oh!)
Promoter:
MBT (2-thiol benzothiazole): easy bonding
ZDMC (zinc dimethyl dithiocarbamate), TMTD (tetramethyl thiuram disulfide): difficult to bond, especially when in the effective vulcanization system, semi-effective vulcanization system.
Anti-coking agent:
Difficult to bond in large quantity, <0.15% easy to bond
Filler:
The type and amount of filler is the key factor.
Carbon black is generally 40-80 parts easier to bond; carbon black main filler rubber containing 3-5 parts of silica is easier to bond.
Elastomers do not use carbon black, but clay and silica, the trend is the same as carbon black.
Plasticizer type and content of the shadow

Plasticizers:
Plasticizers need to be used with caution, the content should not exceed 20phr.
Oil, plasticizers are not conducive to bonding; especially ester plasticizers, ester plasticizers should be less than 10phr.
(1) Wax, oil: migrate to the surface of the elastomer causing bonding difficulties. Including: low molecular weight polyolefins, aromatic oils, fatty acid esters.
(2) Plasticizers: phthalates, adverse to bonding; but high surface area fillers such as silica can neutralize the negative effects of phthalates.
Anti (odor) oxygen agent:
Anti-ozone agent, anti-oxidant in large quantities is unfavorable to bonding; p-phenylenediamine-type anti-(odor) oxygen agent is unfavorable to bonding.
Effect of scorching period:
Long charring period is good for bonding
Influence of Menni viscosity:
Low Mooney viscosity is good for bonding
Influence of hardness of vulcanized rubber:
Between A45 and A85 Shore, easy to bond.
Substrate surface treatment ¦ Method
①Degreasing, mechanical treatment, and cleaning
②Degreasing and chemical treatment

Degreasing, mechanical treatment, cleaning and chemical treatment.
Substrate surface treatment ¦ Degreasing method
▓Lye degreasing
▓ Solvent degreasing
-Impregnation
-Washing
-Steam
▓Ultrasonic degreasing
Lye degreasing ¦
① Main components and characteristics of commonly used lye:
Picture
②Typical steel degreasing lye formula:
Picture
Temperature：80～100℃、Time：20～40 minutes
Solvent degreasing ¦
Commonly used solvents:
120 # gasoline, butanone, ethyl acetate, toluene, xylene
Perchloroethylene, 1,1,1-trichloroethane, acetone, etc.
The workpiece is heavily contaminated and needs to be cleaned twice; even steam degreasing is used.
Steam degreasing ¦
Solvent
1,1,1-trichloroethane, trichloroethylene, perchloroethylene
Metal parts must not intrude into the solvent and must not be above the condensation zone and not in contact with each other.
The temperature of the metal parts reaches the boiling point of the solvent and degreasing is finished.
The PH value of the solvent is kept between 7.0 and 7.5.
The solvent should be renewed when the oil content reaches 25%.
Mechanical treatment ¦
Shot blasting or sand blasting materials: steel balls, diamond sand, quartz sand, adamantine, etc.,.
The parts need to be cleaned after sand blasting or shot blasting.
Substrate surface treatment ¦ Phosphate treatment

Common adhesive method: hard glue method, adhesive method, brass plating method and direct adhesive method.
I. Rigid adhesive method
This method is the first in the metal surface paste or coated with a hard adhesive layer, and then paste the soft adhesive to be bonded, and finally vulcanized to form a whole by hot pressing. Hard glue in the raw rubber content should not be too high, sulfur dosage is generally 30 ~ 40 parts, can be added to improve the adhesive force of iron oxide, dosage of about 20 parts, the bonding temperature can be doubled, more than 20 parts, the performance decline. In order to prevent the free sulfur in the hard glue to the soft glue layer diffusion, you can add a sulfur-free or low-sulfur semi-hard transition layer between the hard glue and soft glue.
Hard glue and metal bonding before the hard glue material with a slurry (solvent with gasoline, the proportion of 1:1.5), the glue