Basic points of formula design

Rubber rollers should have an accurate and uniform surface hardness, and vulcanizates should have good self-adhesive properties. It is also extremely important to select appropriate raw rubber varieties and blending agents. When conducting research in the West, the following points should be noted.

(1) The rubber roller is a thick product. The thickness of the adhesive layer is generally between 20 and 25 mm, but there are also special requirements for thickening to about 40 mm. When considering the West, full attention should be paid to the formula design principles of thick products, which requires a longer flat vulcanization curve to adapt to the characteristics of low-temperature and long-term vulcanization.
(2) Mixture adjustment. The use of hydrated lime as an inorganic accelerator in the formulation of hard rubber prevents the hard rubber from becoming brittle due to excessive sulfur content. When used together with accelerator DM, the performance is better. In addition, the amount of softener should not be excessive, and the use of easily spewed petroleum alkanes should be avoided, otherwise delamination is likely to occur.
(3) Vulcanizing agent. Using high-quality sulfur yellow powder can avoid uneven and insufficient hardness.

Example of formula design
(1) The hardness of the rubber roller is between 90 and 100 (Shore A).
① Selection of glue type. Generally, natural rubber and styrene-butadiene rubber are used together. When the amount of styrene-butadiene rubber is large, the adhesive performance of the rubber layer and the iron core decreases, and the amount of adhesive resin should be increased.
② Vulcanizing agent selection. Mainly sulfur vulcanization, with two options for dosage; First, 40-50 parts, with rapid hardness improvement, surface gloss, and good adhesion to the iron core, but with brittle texture, easy to crack, and poor impact resistance and heat resistance;
The other method is to use 20-30 parts and a large amount of filler to harden. This combination is hard but not brittle, with low heat generation, stable vulcanization, and good heat resistance. However, it is not easily dispersed during mixing, and has adhesive properties in the bonding process.
③ Accelerator selection. "The main organic accelerator is D, with a dosage of about 1 part. A small amount of accelerator M can also be used in combination. Inorganic accelerators, such as zinc oxide, calcium oxide, hydrated lime, are used more frequently.". It can not only play an active role, but also improve elasticity and reduce heat generation. The dosage is 5-10 parts.
④ Softener selection. It is used to improve the process, help disperse the formulation, and increase viscosity, but the dosage should be minimized.

(2) The hardness of the semi rigid rubber roller is between 80 and 85 (Shore A).
① Selection of glue type. For non special performance requirements, natural rubber and styrene butadiene rubber are mainly used (single or combined).
② Vulcanizing agent selection. There are two options for vulcanizing agents, one is the amount of sulfur 20 to 30 parts, and the amount of filler and carbon black 70 to 80 parts. The latter has poor processing performance.
③ Selection of accelerator and softener. The principle of using accelerants and softeners is the same as that of hard rollers.

(3) Soft rubber roller The hardness of soft rubber roller is between 30 and 40 (Shore A), and most of them are printing, dyeing, and printing rubber rollers. Due to different performance requirements, different types of rubber are used, and different coordination systems are used.
① Natural rubber compounding. The minimum hardness is required to be 30 (Shore A), uniform and consistent, with a smooth surface, good elasticity and softness. For softeners, it is necessary to use a large amount to reduce the hardness. If the hardness is required to be around 20 (Shore A), the amount of softener used is equivalent to 1-2 times the amount of raw rubber, but it will cause difficulties in the mixing process and prone to migration. A large amount of ointment can be used to fill to ensure the mobility of the semi-finished product. The vulcanization system generally has a sulfur content of 2.5 to 3 times, and the accelerator selected is mainly one with good vulcanization fluidity and slow molding. Common accelerants M and DM are used alone, with a dosage of about one part. The filler is generally light calcium carbonate, mainly magnesium carbonate, and should not be used in excessive amounts, about 20-30 parts. Other fillers are filled with zinc chloride.
② Nitrile rubber fit. Nitrile rubber is suitable for oil resistant printing rollers. Using synthetic esters as a softener for nitrile rubber should not be used in excessive amounts to avoid spray. It can be used together with ointments to reduce hardness and ensure smooth processing. The total amount used is about 200 parts. The vulcanization system is the same as that of natural rubber, except that the amount of sulfur is slightly lower and the amount of accelerator is slightly higher. Other blends are the same as natural rubber blends.

Please check the details for liquid rubber roller silicone rubber:https://www.rtvsilicone.net/product-abrasion-resistant-printer-rubber-roller-iota-2740-.html