JPS58193134A - Adhering process of steel cord and rubber - Google Patents

Abstract

PURPOSE:To bond steel cord firmly to rubber in the manner such that the tyres of a motorcar using said material may be durable for long period by a method in which the surface of the steel cord is coated with liquid rubber containing COOH or OH, and the steel cord is embedded in the rubber and is vulcanized. CONSTITUTION:The surface of steel cord is coated with liquid rubber containing COOH or OH with the thickness of 0.05-100mum preferably, and the steel cord is adhered to the rubber by burying and vulcanizing said cord in the rubber. The steel cord is preferably plated with brass, copper, zinc or Cu-Zn-Co ternary alloy and further is preferably heat-treated at 80-200 deg.C after plating treatment. Polyisoprene rubber is preferably used as liquid rubber with average viscosity molecular weight of 15,000-50,000, and with per molecule of the rubber COOH content of 3-15 or OH content of 1-10. In the coating process for instance, the steel cord 1 is transferred into a liquid rubber bath 3 by feeding rolls 2 and then is passed through a heating oven 4.

Description

DETAILED DESCRIPTION OF THE INVENTION In particular, an improvement in the method of bonding steel cord and rubber, which is characterized in that the surface of the steel cord is coated with a liquid rubber containing a carboxyl group or a hydroxyl group, and then embedded in the rubber and bonded by vulcanization. Regarding. BACKGROUND OF THE INVENTION Steel tires using steel cords as tire reinforcing material have been widely used due to demands for high-speed durability, high-speed stability, and wear resistance for automobile tires. In general, the durable life of this type of tire is largely influenced by the adhesive strength between the embedded rubber and the steel cord, so many proposals have been made to improve this adhesive performance. There is a method of adding resorgin-formaldehyde resin 1.1d or organic powder ρ)l, but the former causes a rapid decrease in adhesion when exposed to high temperature and humidity conditions or is subjected to external damage.
The strong oxidizing effect of cobalt causes deterioration of unvulcanized rubber and significantly impairs heat aging resistance after vulcanization. In addition, a method has been proposed in which the steel cable wire is plated with a ternary alloy consisting of zinc and cobalt, and the cobalt layer is made to have a weight of 01 to 20% of the total weight (Japanese Patent Laid-Open No. 1983-1993). -71887), compared to the case where brass-plated steel wire is vulcanized and bonded in embedded rubber containing organic Zbalt salts, this method improves the adhesion during tire manufacturing, so-called -
It cannot be said that the subsequent adhesion is necessarily sufficient. In general, in order to improve the adhesion of rubber embedded in steel cords, it is necessary to address both the problem of adhesion during tire manufacture as well as the problem of deterioration of adhesion with long-term use. As a result of extensive research, we have arrived at the present invention.

The present invention is a method for adhering a steel cord to rubber, which is characterized in that the surface of the steel cord is subjected to S treatment with a liquid rubber having a carboxyl region or a hydroxyl group, and then embedded in the rubber and vulcanized.

The liquid rubber used in the present invention is polyisoprene or polybutadiene and has a viscosity average molecular weight of 500 to 50,000.
It is particularly preferably in the range of 15,000 to 50,000. If the viscosity average molecular weight is less than 500, the physical properties of the vulcanized rubber will deteriorate, while if it exceeds 50,000, the workability and penetration of the rubber into the inside of the cord will be impaired, which is not preferable. In order to improve workability, a commonly used solvent such as naphtha may be mixed with the liquid rubber. Note that the liquid rubber has active groups such as carboxyl groups or hydroxyl groups, and it is desirable that each molecule contains 1 to 15 active groups. The more active groups per molecule, the higher the affinity with steel cord, but the reverse t
The compatibility of the embedded rubber with the diene rubber decreases, making it impossible to improve physical properties through co-vulcanization.

When the active group is a carboxyl group, it is usually 3 to 1511% per molecule, and when it is a hydroxyl group, it is 1 to 1% per molecule.
Contains 10 pieces.

In addition, when coating the steel cord with the liquid rubber, the steel cord is continuously immersed in a bath filled with liquid rubber, and the surface of the steel cord is coated with the liquid rubber α05).
A film with a thickness of t~1007 is formed. Here, it is necessary to adjust the viscosity of the liquid rubber appropriately so that the liquid rubber sufficiently penetrates into the internal voids of the steel cord and forms a film of a predetermined thickness. In this case, a solvent may be used.

In addition, 15 to 5 parts of organic cobalt salt is mixed into the liquid rubber during the formation of a corrugated film on the steel cord, as well as sulfur and a vulcanization accelerator.

General-purpose fillers can be added, thereby further improving adhesion.

Next, in the present invention, after coating the steel cord with liquid rubber,
It is desirable to treat the coated cord at a temperature of 3 to 10 minutes for 18 minutes to minimize the effects of moisture, water, etc. during storage of the coated cord and to stabilize the adhesion.

The steel cord used in the present invention is normally plated with brass, but in order to improve the wire drawing workability and adhesion stability of the cord, the composition is ternary plated with steel, lead, and cobalt. For example, wA55~74 city-produced Yu, zinc 13~
42 heavy weight, cobalt 0.4-12t & excellent can be used.

In addition, in the present invention, the steel cord coating treatment method is as shown in FIG.
This is carried out by feeding the liquid rubber into a bath (3) at step (2), and then passing it through a drying and heating opening (4).

However, in the method of the present invention, when the surface of the steel cord is coated with liquid rubber, the liquid rubber penetrates into the internal voids of the steel cord, which effectively prevents the occurrence of rust due to moisture, etc., reduces the low adhesive strength, and makes it easier to bury the cord. It becomes possible to further improve the initial adhesive strength when vulcanized and bonded in rubber.

Example 1 For the two types of adhesive rubber shown in Table 1, 100 parts by weight of liquid rubber was mixed with the rubber component of the adhesive rubber compound, and this was coated with a steel cord with a thickness of 50 L. It was then embedded in rubber and vulcanized and bonded. The adhesion was evaluated and [1] 2, 2, 4-trime
thyl-1+2-dihydroquinoline
.

+2) NIN-DicyclOhexyl-2-ben
zothiazolylsulfenamide.

Note 1) Liquid polyisoprene rubber without active groups, viscosity average molecular j 29.000, Clareprene L Engineering R-'5
0 (Kuraray Isoprene Chemical 14ν) Note 2) Liquid polyisoprene rubber having about 10 carboxyl groups/molecule, viscosity average molecular weight 25,000, Kuraray Isoprene L Engineering R-410 (Kuraray Isoprene Chemical 1)
Note 3: Liquid polybutadiene rubber with hydroxyl groups of 0.83 m3/y, number average molecular weight of 2,80 R-45HT
(Idemitsu Petrochemical System) The results are shown in Table 1, and the evaluation of Naori c adhesion was carried out after being aged under condition F at high temperature and high humidity (80°C, 90% humidity). It was measured. Adhesion was determined by making incisions in the embedded rubber along the direction in which the steel cords were arranged, as shown in FIG. 2, and measuring the amount of rubber adhered after this was peeled off.

In Table 1, experiment numbers 1 to 4 are comparative examples, and experiment numbers 5 to 4 are comparative examples.
18 is an example. When the adhesive rubber contains sulfur, an additive accelerator, and cobalt naphthenate (Experiment No. 13)
, 141, When a ternary alloy is used to plate a steel cord, the adhesion improves by -1 by heat treatment (Experiment No. 9.10).

[Brief explanation of drawings]

Figure 41 is a schematic diagram of the process of coating a steel cord with liquid rubber, and Figure 2 shows the state of peeling of the rubber in an adhesion test. Patent applicant: Sumitomo Rubber Industries, Ltd. Agent: Yoshihira Nakamura, patent attorney

Claims (1)

[Scope of Claims] (1) A method for adhering a steel cord to rubber, which comprises coating the surface of the steel cord with a liquid rubber having a carboxyl group or a hydroxyl group, and embedding the cord in the rubber and vulcanizing it. (21 steel cord is brass, copper, zinc or copper-zinc-
The bonding method according to claim 1, wherein cobalt ternary alloy plating is applied. (31 Liquid rubber has a viscosity average molecular weight of 15,000 to 5o,
o o o with carboxyl group content of 3 to 1 molecule
15, or the hydroxyl group content is 1 to 101 per molecule
Claim 1, which is a hard polyisoprene rubber
Adhesion method described in section. (4) The adhesion method according to claim 1, wherein the coating-6 is in the range of 0.057 to 10 Q, g. (5) After the steel cord is treated, the steel cord is further heat treated at a temperature of 80 to 200°C.