CS217577B1 - Bonding agent for improving bond strength of silicone rubber with porous silicate surfaces - Google Patents

Abstract

The purpose of the invention is to improve the bonding of porous silicate surfaces with silicone rubber made from a single-component silicone rubber with an oxime vulcanizing agent. The said purpose is achieved by first applying to the bonded surfaces of the porous silicate surfaces a bonding agent consisting of methylphenyl silicone resin and butyl methacrylate resin and Co naphthenate in an aromatic hydrocarbon solution.

Description

BACKGROUND OF THE INVENTION The present invention relates to a bonding agent for improving the bond strength of silicone rubber to porous silicate surfaces.

When a one-component silicone rubber is used to bond dilating materials, a higher adhesion of the joint is required than that of the silicone rubber, i.e. to avoid tearing at the joint under stress. In the case of bonding of silicate porous elements, the bond strength is limited in time due to the effect of moisture and residual alkali.

This lack of time-limited bond strength between a porous silicate surface and a silicone rubber made from a one-component rubber with an oxime vulcanizing sensor removes the composition of the invention which contains 40 to 85 parts by weight of methylphenyl silicone resin with an R / Si ratio of 0.7 to 1.0 Ph / Me 0.7 to 1.3 and 15 to 60 parts by weight of butyl methacrylate resin in dry matter. As the solvent, aromatic hydrocarbons such as toluene can be used. The drying time can be shortened by adding a desiccant, for example cobalt naphthenate in a concentration of 0.1 to 0.4% cobalt, to the non-volatile content.

The advantages of the proposed fastener according to the invention are good penetration into the porous silicate surface, solidification of the silicate surface to form a continuous film layer, short drying time at room temperature, long-term resistance to humidity and alkaline environment and higher adhesion to silicone rubber from one-component silicone rubber is the strength of this rubber. Example 1

A bonding agent containing 50 parts by weight of methylphenyl silicone resin with a methyl / Si ratio of 1.0 and phenyl / methyl of 0.7 and 50 parts by weight of butyl methacrylate resin was applied to the surfaces to be joined. Toluene was used as solvent. The binder dry weight was 50%.

According to ČSN 722341, the concrete elements were always bonded after 2 hours with a one-component silicone rubber with an oxime vulcanizing agent. By way of comparison, the concrete bodies were joined by the rubber without using a fastener. After 14 days all bodies were immersed for 7 days in a saturated solution of lime milk and the adhesion of silicone rubber to concrete was determined according to ČSN 722341.

In the case of the samples with the fastener used, there was in all cases a collision fracture, in all the samples without the fastener used there was an adhesive fracture, i.e. in the concrete-rubber joint.

Example 2

A bonding agent was applied to the bonded surfaces of the concrete bodies which contained 72 parts by weight of methylphenyl silicone resin with a methyl / Si ratio of 1.0 and phenyl / methyl of 0.7 and 28 parts by weight of butyl methacrylate resin; Toluene was used as solvent. The binder solids were 63%. A cobalt naphthenate solution was added in an amount of 0.2% by weight of cobalt to the non-volatile content to accelerate drying. 30 minutes after application of the fastener, the concrete bodies were bonded with a one-component silicone rubber to the oxime vulcanizing agent. By way of comparison, the concrete bodies were joined by the rubber without using a fastener. After 14 days, all the bodies were immersed for 7 days in a saturated solution of lime milk and the adhesion of the silicone groove to the concrete was determined according to ČSN 722341.

In the samples with the fastener used, cohesive fracture occurred in all cases, in all the samples without the fastener used an adhesive fracture, i.e. in the concrete-rubber joint.

E r i 1 and d 3

A bonding agent containing 32.5 parts by weight of methylphenyl silicone resin having a methyl / Si ratio of 0.7 and phenyl / methyl of 1.3 and 17.5 parts by weight of butyl acrylate resin to dry matter was applied to the bonded surfaces of the concrete bodies. Xylene was used as solvent. To speed up drying, cobalt naphthenate was added in an amount of 0.2% cobalt to the non-volatile content. 30 minutes after application of the fastener, the concrete bodies were bonded with a one-component silicone rubber to the oxime vulcanizing agent. By way of comparison, the concrete bodies were joined by the rubber without using a fastener. After 14 days all bodies were immersed for 7 days in a saturated solution of lime milk and the adhesion of silicone rubber to concrete was determined according to ČSN 722341.

In the case of the samples with the fastener used, there was in all cases a cohesive fracture, in all the samples without the fastener used there was an adhesive fracture, i.e. in the concrete-rubber joint.

Claims (2)

CLAIMS 1. A bonding agent which improves the bond strength of silicate porous surfaces with silicone rubber made of a one-component silicone rubber with an oxime vulcanizing agent, comprising 40 to 85 parts by weight of methylphenyl silicon resin having a methyl / Si ratio of 0.7 to 1.0 and phenyl / methyl 0.7 to 1.3, VYNALEZU 15 to 60 parts by weight of butyl methacrylate resin and contains toluene or xylene as solvent. 2. The binder as claimed in claim 1, comprising from 0.1 to 0.4% by weight of cobalt in the form of cobalt naphthenate based on the nonvolatile proportions of the binder.