The Influence of the Cation in Organometallic Boroacylate Adhesion Promoters on the Adhesion Between Steel Cord and Skim Rubber Compound

The influence of transition metal cations (cobalt, nickel and zinc ion) associated with organometallic boroacylate adhesion promoters on the adhesion between brass-coated steel cord and rubber skim compound under the influence of various environments, which simulate tyre service conditions, has been studied.

Incorporation of adhesion promoters individually in the steel cord-skim formulation leads to increase in crosslink density, Young's modulus and cord pull-out force. The adhesion energy is enhanced significantly with the addition of cobalt adhesion promoter. The performance of the promoter is influenced by the ease of dissociation of the transition metal ion from the promoter, its participation in the rubber curing and the modification of the interfacial film responsible for adhesion. During aerobic ageing, cobalt followed by nickel is found to be effective, whereas cobalt and, partially, zinc salts offer certain resistance to thermal ageing. Against salt and steam ageing, cobalt boroacylate is very effective followed by zinc salts. The influence of the variation of concentration of zinc ion on adhesion energy is not appreciable. The study points towards the supremacy of cobalt ion among the cations studied, considering its overall good performance and the protection offered against various hostile environments.     

钴盐对钢丝帘线与橡胶粘合性能的影响

对环烷酸钴，硼酰化钴，新癸酸钴等钴盐粘合增进剂对高和低铜质量分数钢丝帘线与橡胶粘合性能的影响进行了研究。结果表明，胶料中加入钴盐能够提高强伸性能和与钢丝帘线的初始粘合唱 力及耐盐水老化能力。     

橡胶粘合促进剂的研究概况及发展趋势

本文综述了日益广泛应用在橡胶金属复合材料特别是轮胎工业中的子午线轮胎生产中的一类新型橡胶粘合促进剂一硼酰化钴的国内外生产应用情况,评述了橡胶粘合促进剂的研究主其作用机理,同时比较了硼酰化钴与传统钴皂粘合促进剂对橡胶一钢丝帘线的粘合性能。     

Study of Cu–Zn–Co ternary alloy-coated steel cord in cobalt-free skim compound

In this study, it is shown that the rate of bond degradation due to ageing in hot & humid conditions can be significantly reduced by the use of a Cu–Zn–Co ternary alloy coating, compared to current compounds and normal brass-coated steel cord. To better understand the adhesion mechanism, X-ray photoelectron spectroscopy is used to investigate the adhesion interface upon hot and humid ageing. In addition, the effect of removal of cobalt salts from compound on static and dynamic rubber compound properties is studied: it is found that this leads to improved heat ageing resistance, slower crack growth rate and less hysteresis. Hence, the new Cu–Zn–Co ternary alloy coating for steel cord allows cobalt salts to be removed from tires, which makes tires more durable and eco-friendly.     

SEM/EDX studies of the influence of a cobalt adhesion promoter on the interface between rubber skim compounds and tire steel cord

The failed interfaces between natural rubber skim compounds and tire steel cord used as tire cord adhesion test (TCAT) specimens have been studied by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis in order to understand the influence of cobalt boroacylate in the rubber compound as an adhesion promoter. SEM studies indicated a mixture of cohesive failure in the rubber and interfacial failure between the rubber and the brass coating. Cobalt boroacylate leads to more cohesive failure of the rubber (about 88% of the cord area covered by the rubber compared with 73% by the control), due to its degradative effects on rubber. EDX analysis of the failed cord and rubber surfaces at various points gave the concentrations of copper, zinc, cobalt, iron, silicon, sulfur, oxygen, and carbon. Assuming van Ooij's model of interfacial sulfide film formation over the brass (Cu/Zn) layer and analyzing the EDX results, it is clear that the failure occurs at the Cu/Zn and Cu_xS/ZnS sub-layers.     

Adhesion between rubber compounds and ternary-alloy-coated steel cords,Part I: effect of cobalt plating amount in ternary-alloy-coated steel cords

The adhesion between a rubber compound and ternary-alloy-coated steel cords with different cobalt plating amounts (0, 2 and 4 wt%) was investigated to understand the role of cobalt in stabilizing adhesion to the rubber compound. The adhesion property of ternary alloy coated steel cords to the rubber compound did show significant enhancement after cure for the ternary alloy coated steel cord with 2 wt% cobalt plating. Further increase of cobalt plating in ternary-alloy-coated steel cord was responsible for the poor adhesion to the rubber compound. An improvement in adhesion durability after aging in various hostile environments was shown for the ternary-alloy-coated steel cord with 2 wt% cobalt plating. The interphase between the ternary-alloy-coated steel cords and the rubber compound studied using AES showed a stable adhesion interphase by optimum cobalt plating, resulting in enhancement of adhesion retention.     

钴盐在钢丝帘线粘合体系中的应用

对不同粘合体系，不同牌号钴盐在全钢子午线轮胎中的应用进行了探讨。结果表明。间甲白钴复合粘合体系综合性能最佳。不同钴盐对胶料物性和初始粘合无明显影响，硼酰化后的粘合保持率和覆胶率明显高于其它钴盐，尤其是耐汽老化和盐水老化性能较好。正交设计得出粘合体系主要因素最佳用量组合为间苯二酚1.5，粘合增进剂6，硫黄6.5，硼酰化钴1.1，大料及产品试验结果表明，优选配方达到技术指标和产品使用性能要求。     

Adhesion between rubber compounds and ternary-alloy-coated steel cords. Part II: Effects of sulfur and cobalt salt in rubber compounds

The adhesion properties between rubber compounds with different amounts of cobalt salt and sulfur and ternary-alloy-coated steel cord with 2 wt% cobalt plating amount were investigated to understand the effects of cobalt salt and sulfur in rubber compounds on their adhesion characteristics to the ternary-alloy-coated steel cord. The adhesion properties of the rubber compounds to ternary-alloy-coated steel cord were largely dependent on the amounts of both cobalt salt and sulfur in the rubber compounds. The pull-out force of adhesion sample increased significantly with increasing concentration of cobalt salt in the rubber compound with constant sulfur loading, while it decreased slightly with increasing sulfur into the rubber compound with constant cobalt salt loading. Adhesion retention after various hostile aging treatments improved in the rubber compounds incorporating both cobalt salt and high loading of sulfur. The interphases between the rubber compounds and the ternary-alloy-coated steel cord studied using AES showed stable adhesion patterns by incorporating cobalt salt, resulting in enhancement of the adhesion retention.     

Synthesis of Cobalt Adhesion Promoters and Their Evaluation in a Passenger Radial-Belt Skim Compound

Cobalt adhesion promoters have gained considerable acceptance in the rubber industry during the past two decades and are considered the most important tool for the promotion of adhesion between the rubber compound and the brass-plated steel cord in the manufacture of steel-cord-reinforced radial tires. Most of the commercially available cobalt compounds are either higher fatty acid salts or cobalt–chelate complexes, e.g., cobalt octanoate, napthenate, stearate, and cobalt–boron complexes. Of the various cobalt salts and chelate complexes, cobalt–boron complexes are the most popular, and they form good bonding. Considering the availability, economics, and performance of this material, an attempt has been made in this study to synthesize different cobalt–chelate complexes, make a comparative evaluation of rubber compounds, and simulate field performance with laboratory tests.     

Synthesis of Cobalt Adhesion Promoters and Their Evaluation in a Passenger Radial-Belt Skim Compound

Cobalt adhesion promoters have gained considerable acceptance in the rubber industry during the past two decades and are considered the most important tool for the promotion of adhesion between the rubber compound and the brass-plated steel cord in the manufacture of steel-cord-reinforced radial tires. Most of the commercially available cobalt compounds are either higher fatty acid salts or cobalt-chelate complexes, e.g., cobalt octanoate, napthenate, stearate, and cobalt-boron complexes. Of the various cobalt salts and chelate complexes, cobalt-boron complexes are the most popular, and they form good bonding. Considering the availability, economics, and performance of this material, an attempt has been made in this study to synthesize different cobalt-chelate complexes, make a comparative evaluation of rubber compounds, and simulate field performance with laboratory tests.     

A novel promoter for enhancing adhesion between natural rubber and brass-plated steel cords

In this study, a conventional manobond promoter as well as a newly synthesized kaolin modified resin (KMR) were applied in various concentrations into rubber mixes to investigate their performance in improving the adhesion between NR and brass-coated steel cords. Two types of steel cords were used to prepare T-shape samples for pullout test. The samples were aged under aerobic aging conditions or exposed to ionizing radiation and the adhesion force was examined. The analysis of variance (ANOVA) was used to obtain a general understanding of the impact of changing various parameters and their inter-relationships on the static adhesion between NR and brass-coated steel cords. The results revealed that the use of the prepared promoter has significantly resulted in the clear stability of the cure rate index of the NR mixes. Also, the presence of KMR in the rubber mix enhances the mechanical properties of the rubber to a great extent. The results showed also that the NR mixes with KMR promoter have higher adhesion levels than those of the manobond promoter.     

钴盐用量对橡胶与钢丝帘线粘合性能的影响

对硼酰化钴ＭＣ２３（钴质量分数为２３％）用量（０６～１６份）对橡胶与钢丝帘线粘合性能的影响进行研究。采用的基本配方为：ＮＲ１０００；炭黑Ｎ３２６６２０；芳烃油８０；氧化锌９０；硬脂酸０５；防老剂４０２０２０；不溶性硫黄ＩＳ７０２０６０；促进剂ＤＺ１０；粘合剂ＲＳ３５；粘合剂Ａ２３；沉淀法白炭黑５０。结果表明，随着钴盐用量的增大，在未老化、热空气老化及盐水老化条件下，胶料与钢丝的粘合强度有所提高；在湿热老化条件下，粘合强度由于热量和湿气的交互作用而发生较大幅度的下降，但钴盐用量在１０份时粘合强度的下降为最小。综合胶料初始和老化后的应力应变性能和粘合强度，以１０份钴盐用量为最佳。     

EFFECT OF CURE RATE OF RUBBER COMPOUND ON THE ADHESION TO COPPER-PLATED STEEL CORD

Copper-plated steel cord was prepared and its adhesion properties to rubber compounds, which have different loading amounts of both sulfur and accelerator, were examined in comparison with brass-plated steel cord. The lower pullout force of copper-plated steel cord to the rubber compounds was shown compared with brass-plated steel cord. The copper-plated steel cord showed higher adhesion retention to rubber compounds than brass-plated steel cord against various hostile environments. The stability against both humidity aging and thermal aging, and the cause for the high adhesion retention of the copper-plated steel cord to rubber compounds, were discussed compared with those of the brass-plated steel cord. The pullout force of copper-plated steel cord to rubber compound is inversely correlated with cure rate after various aging treatments.     

Effect of cure rate of rubber compound on the adhesion to copper-plated steel cord

Copper-plated steel cord was prepared and its adhesion properties to rubber compounds, which have different loading amounts of both sulfur and accelerator, were examined in comparison with brass-plated steel cord. The lower pullout force of copper-plated steel cord to the rubber compounds was shown compared with brass-plated steel cord. The copper-plated steel cord showed higher adhesion retention to rubber compounds than brass-plated steel cord against various hostile environments. The stability against both humidity aging and thermal aging, and the cause for the high adhesion retention of the copper-plated steel cord to rubber compounds, were discussed compared with those of the brass-plated steel cord. The pullout force of copper-plated steel cord to rubber compound is inversely correlated with cure rate after various aging treatments.     

粘合增进剂AIR-1在载重斜交轮胎帘布胶中的应用

研究了粘合增进剂AIR－1在载重斜交轮胎9．00－2016PR缓冲胶、胎体外层帘布胶和内层帘布胶中的应用效果。试验结果表明，加入5份粘合增进剂AIR－1，可明显提高胶料与帘线之间的H抽出力和粘合强度以及胶料的热老化性能，提高成品轮胎帘布层间的粘合强度的耐久性，并可降低胶料成本。     

On characterizing microscopically the adhesion interphase for the adhesion between metal and rubber compound Part III. Effect of brass-plating amount for brass-plated steel cord

Three kinds of brass-plated steel cords with different brass-plating amounts from 2.62 to 5.01 g/kg were prepared and their adhesion properties to rubber compounds were studied. Adhesion properties decreased with the increase in the brass-plating amount from 2.62 to 3.88 g/kg. Furthermore as the increase of brass-plating amount over 3.88%, adhesion property increased. The strong adhesion of brass-plated steel cord with low brass-plating amount to the rubber was shown not only after curing but also after hostile aging treatments. The good adhesion stability against humidity aging of adhesion property for brass-plated steel cord with low brass-plating amount to rubber compound was discussed in terms of the formation and growth of adhesion interphase determined by AES depth profile. The good adhesion stability of brass-plated cord with low brass-plating amount can be resulted from the suppression of the excessive growth of copper sulfide and the inhibition of dezincification due to the low brass-plating amount.     

Adhesion Between Rubber Compounds Containing Various Adhesion Promoters and Brass-Plated Steel Cords. Part I. Effect of Sulfur Loading in Rubber Compounds

The adhesion property between rubber compounds containing different types of adhesion promoters (resinous adhesion promoter (containing both methylene donor and methylene acceptor), cobalt salt and zinc borate) and different loading amounts of sulfur and brass-plated steel cords was investigated to understand the effect of sulfur loading in the rubber compounds on their adhesion characteristics to the brass-plated steel cords. The adhesion property of the rubber compounds to brass-plated steel cords was largely dependent on both the type of adhesion promoter and the loading amount of sulfur in the rubber compounds. The pull-out force of adhesion samples increased significantly with increasing loading amount of sulfur in the rubber compounds containing resinous adhesion promoter, whereas it decreased slightly with increasing loading amount of sulfur in rubber compounds containing cobalt salt or zinc borate. In humidity aging, the best adhesion retention was observed in the rubber compound containing zinc borate and low loading of sulfur. Regardless of the type of adhesion promoter, adhesion retention after thermal aging treatments improved with increasing loading amount of sulfur in the rubber compounds. The adhesion property was interpreted in terms of the interphases formed between the rubber compounds and the brass-plated steel cords as studied using Auger electron spectroscopy.     

Bonding of Natural Rubber to Steel: Surface Roughness and Interlayer Structure

This paper is concerned with two aspects of the adhesion produced by the vulcanisation bonding of a simple natural rubber (N.R.) compound to mild steel. Adhesion was measured using a 45° peel test.

When the N.R. was bonded, using a proprietary bonding agent (Chemlok 205/220), to 'smooth' steel (acid etched) or to 'rough' steel (phosphated) high values of peel energy (≥ 4.5 kJm^-2), and good environmental resistance to water were obtained, with failure cohesive largely within the rubber. The highest values of peel energy (≈ 7.5 kJm^-2) were associated with a phosphated surface which consisted of plate-like crystals which directed the stresses away from the substrate in a way which produced a failure surface within the rubber which showed extensive tearing and cracking.

The nature of the layer formed in the interfacial region by interaction between bonding system and rubber was investigated using a chlorinated rubber as a 'model compound' representing the adhesive and uncompounded N.R. to represent the rubber. When a blend of the two was heated in air at 150°C, evidence was found of a solid state chemical reaction in which carbonyl groups were incorporated into the blend which became visually homogeneous. Further evidence points to the relevance of this change to adhesion in rubber-to-metal bonding.     

Investigation of the effects of adhesion promoters on the adhesion properties of rubber/steel cord by a new testing technique

The effects of adhesion promoters, cobalt decanoate and PN759 (modified resorcinol) on the static and dynamic adhesion properties of rubber/steel cord in a carcass recipe are examined. A new testing method with special rubber/steel cord specimens was developed. It was found that cobalt decanoate could improve the static adhesion and favored the dynamic adhesion of rubber/steel cord so that adhesive failure mainly occurred in rubber phase. A resorcinol‐formaldehyde‐silica promoting system was deleterious to adhesion stability, but improved initial adhesion strength. PN759 improved the dynamic mechanical properties compared with resorcinol for the carcass vulcanizates at strains less than 10%. PN759 instead of resorcinol slightly improved the static and dynamic adhesion and the probability that adhesion failure occurred in the interphase was similar to that occurring in the rubber phase. The dynamic “pull‐out forces” for samples with 1.0 phr cobalt decanoate first increased and then decreased with the increase in the number of fatigue cycles and reached a maximum at 100,000 fatigue cycles. The covered rubber on the “pulled‐out” cord after fatigue appeared to form a screw thread form and the greater pull‐out force corresponded to more uniform and narrower screw threads. SEM images indicated that un‐dispersed filler agglomerates could be the initiating factor for adhesive failure. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39460.     

Synthesis of cobalt complexes and their evaluation as an adhesion promoter in a rubber–steel wire system

Cobalt adhesion promoters are considered as one of the most important ingredients in the tyre industry for adhesion between the rubber compound and the brass plated steel cord for manufacturing of steel-belted radial tyres. Most of the commercially available cobalt compounds are either higher fatty acid salts, or cobaltchelate complexes, e.g., cobalt octate, naphthenate, stearate and cobalt-boron complexes. Among all the available cobalt salts, cobalt-boron complexes are the most popular ones and bond well. Considering the availability, economics and performance of the different cobalt salts, an attempt has been made in this study to synthesise different cobalt-chelate complexes and to make a comparative evaluation. In some of the cases the cobalt complexes developed showed better adhesion properties as compared to the control compound.