수지류 접착증진제 첨가량이 다른 배합고무의 물성과 황동이 피복된 강선코드와 접착성질을 조사하였다. Methylene acceptor인 resorcinol formaldehyde resin(RFR)은 0에서 4 phr, methylene donor인 hexamethoxymethylmelamine(HMMM)는 0에서 5 phr까지 첨가량을 다르게 하여 실험하였다. RFR과 HMMM이 첨가된 고무에서 가황속도는 느려지고 최대토크가 낮아졌다. RFR이 조금 첨가된(2 phr) 배합고무에서 모듈러스는 높아졌으나, 첨가량이 많아지면(3 phr) 모듈러스는 도리어 낮아졌다. 두 첨가제의 함량비에 따라 인장강도와 연신율이 달라졌다. 고무 물성의 변화는 수지류 첨가제에서 생성된 수지층에 의한 점도의 증가 또는 과잉 첨가제의 윤활 및 희석효과로 설명될 수 있었다. 접착가황 직후 황동 피목코드와 접착성질은 RFR과 HMMM이 첨가된 고무에서 낮았으나, 습윤열화 처리 후 접착성질은 향상되었다. 반면 첨가량비가 맞지 않거나 과잉 첨가되면 접착성질은 도리어 저하된다. 수지류 접착증진제가 반응하여 접착계면 주위에 점도가 큰 수지층을 형성하여 계면으로 수분의 이동을 억제하므로 접착열화가 느려지는 것으로 설명될 수 있었다. 가황속도에 대해서는 HMMM의 영향이 크나, 접착성질이나 고무 물성은 분자량과 점도가 큰 RFR의 영향이 상대적으로 컸다.

The physical properties of rubber compounds and adhesion characteristics with brass-plated steel cord were investigated with the loadings of resin promoters. Resorcinol formaldehyde resin(RFR) as methylene acceptor was loaded from 0 to 4 phr, and hexamethoxymethylmelamine(HMMM) as methylene donor from 0 to 5 phr. With loading RFR and HMMM on rubber compounds, cure rate and maximum torque were decreased. The modulus of the rubber compound with low loading(2 phr) of RFR was slightly high, but the modulus was low for high loading(3 phr) of RFR additives. Tensile strength and elongation at break were varied with the loading amount and the ratio of resin promoters. The changes in the physical properties with resin additives were responsible for the formation of viscous resin layer at adequate addition, but lubricant and dilution effects at excessive loading. Adhesion properties of unaged adhesion samples containing RFR and HMMM were poor, but those after humidity aging treatment were enhanced. But the adhesion properties were poor at the rubber compound of inappropriate ratio and excessive loading of resin promoters. The high viscous resin layer formed for RFR and HMMM might suppress water diffusion to the adhesion interface during humidity aging, resulting in the slow rate of adhesion degradation of rubber compound containing resin promoters. The change in the cure rate was large with HMMM addition comparing to RFR, whereas the effect of RFR addition on the adhesion properties and the physical properties was relatively large due to its high molecular weight and viscosity.

Adhesion Rubber Compounds Steel Cord Resorcinol Formaldehyde Resin Hexamethoxymethylmelamine

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