JP2000044735A - Aqueous cement for tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous cement for tires having an improved unvulcanized adhesiveness. SOLUTION: This aqueous cement contains a rubber latex, carbon black which has a nitrogen adsorption specific surface area of 60-200 m2/g and a dibutylphthalate oil absorption of 60-180 ml/100 g, and an adhesiveness-providing resin. The adhesiveness-providing resin is preferably at least one selected from the group consisting of a coumarone-indene resin, a phenol-terpene resin, a petroleum hydrocarbon resin and a rosin resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based cement for tires, and more particularly to a water-based cement applied to the surface of a tire rubber member, and more particularly to a water-based cement for tires having improved unvulcanized adhesiveness.

[0002]

2. Description of the Related Art Conventionally, carbon black has been frequently used as a reinforcing filler in tires. This is because carbon black can provide high reinforcing properties and excellent wear resistance as compared with other fillers. On the other hand, in response to the recent social demands for energy saving, in order to reduce the fuel consumption of automobiles and reduce the heat generation of the tires, that is, to reduce the rolling resistance, it is necessary to reduce the filling amount of the carbon black or reduce the carbon black having a large particle size. It is known that in any case, the reinforcement, wear resistance, and grip on wet road surfaces are inevitable. In order to solve such a problem, conversion from carbon black to silica particles has been attempted in recent years. However, this silica has poor conductivity, and the tires are charged while running, which causes radio noise when the running tire touches a conductive material such as a manhole cover, or gasoline. There is a problem that gasoline may be ignited at a station or the like. Therefore, in reality, automobile manufacturers are actively researching to improve the conductivity of silica-filled tires.

[0003] Methods of improving the conductivity of a tire mainly include (1) a method of introducing a conductive strip inside the tread, and (2) a method of applying conductive cement to the tread surface of an unvulcanized tire. Attempted. The above method (1) is a method of replacing a part of the tread of a silica-filled tire with a conductive substance to prevent the tire from being charged, and many proposals have been made so far, but generally the tire performance is deteriorated. There is a problem that there is a danger. On the other hand, since the method (2) is a method of applying to the tread surface of an unvulcanized tire, it can be easily implemented. In this method, the conductive cement adhered to the surface of the tire tread has a problem that it easily falls off during running.However, the conductive cement adhered to the inner wall of the tread at the time of vulcanization molding enters the groove of the tread. Is known to hardly fall off and to be maintained until the end of traveling. Further, in order to enhance the moldability of the tire, cement is applied between the members like a tread under cement. These cements are classified into an organic type and an aqueous type, but the organic type is not preferable from the viewpoint of a working environment because an organic solvent is used. A water-based material has no problem in terms of the working environment, but has a disadvantage that its adhesiveness to an unvulcanized tire member is inferior to an organic material.

[0004]

SUMMARY OF THE INVENTION The present invention is used in such a situation, in particular, to impart conductivity to a silica-containing tire tread. It is an object of the present invention to provide a water-based tire for tires having improved adhesion to a sulfurized tire tread.

[0005]

SUMMARY OF THE INVENTION The present inventors have developed an unvulcanized adhesive.
Study on water-based cement for tires with improved durability
Of rubber latex and specific colloidal properties
Water-based cement containing carbon black with
In addition, by containing a tackifier resin,
Was found to be achieved. The present invention is based on this finding.
It was completed based on that. That is, the present invention
Aqueous sema containing latex and carbon black
The nitrogen adsorption ratio of the carbon black
The product is 60 to 200 m ^Two/ G], dibutyl phthalate absorption
Oil volume is 60-180 [ml / 100g]
And a resin containing a tackifying resin.
Water-based cement.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber latex used in the water-based cement of the present invention is not particularly limited. For example, NR (natural rubber), SBR (styrene-butadiene rubber), IR (polyisoprene synthetic rubber), BR (BR) Latexes containing at least one selected from polybutadiene rubber), NBR (acrylonitrile-butadiene rubber), IIR (butyl rubber), NSBR (acrylonitrile-styrene-butadiene rubber) and the like can be mentioned. The rubber latex can be manufactured by a conventionally known method, and the concentration of the rubber component in the latex is not particularly limited. The water-based cement of the present invention has a nitrogen adsorption specific surface area of 60 to 200 [m ² / g], preferably 70 to 180, in order to provide reinforcement.
[M ² / g], dibutyl phthalate oil absorption of 60 to 18
0 [ml / 100 g], preferably 70-160 [ml
/ 100 g] is used. If the nitrogen adsorption specific surface area is less than 60 [m ² / g], the particle size of the carbon black becomes too large and the reinforcing property cannot be sufficiently exhibited, and the cement is applied to the tread surface and used as a conductive cement. in case of,
It becomes difficult to form a conductive path. On the other hand, if the nitrogen adsorption specific surface area exceeds 200 [m ² / g], the cost increases and the adhesion to the rubber member deteriorates. If the dibutyl phthalate oil absorption is less than 60 [ml / 100 g], the structure as an aggregate of carbon black particles hardly develops, and not only does the reinforcing property of the cement deteriorate, but also no conductive path is formed. On the other hand, when the dibutyl phthalate oil absorption exceeds 180 [ml / 100 g], the carbon black for tires loses the colloidal properties and the cost increases. The content of the carbon black in the water-based cement is selected in the range of usually 40 to 60 parts by weight, preferably 45 to 55 parts by weight, per 100 parts by weight of the rubber component in the rubber latex. If the content of carbon black is less than 40 parts by weight, sufficient reinforcing properties cannot be obtained. On the other hand, if the amount exceeds 60 parts by weight, no improvement in the effect corresponding to the content is recognized, which is economically disadvantageous.
Examples of such carbon black include HAF, ISAF, and SAF commonly used in rubber compositions for tires.
Etc. can be used.

In the water-based cement of the present invention, it is necessary to contain a tackifying resin for the purpose of improving the adhesion to an unvulcanized tire member. As the tackifying resin, the adhesiveness with an unvulcanized tire member is enhanced,
It is not particularly limited as long as it can be emulsified and dispersed in the aqueous cement. Examples of the resin include coumarone - indene resins; beta-pinene resins, terpene resins such as α- pinene resin; phenol - terpene resins; C ₅ petroleum resins, petroleum hydrocarbon resins such as C ₉ petroleum resin A phenolic resin obtained by the reaction of an alkylphenol with formaldehyde; a xylene resin; a rosin-based resin; a dicyclopentadiene resin; a styrene-based resin. Of these, cumarone-indene resin and phenol-terpene resin from the viewpoint of effect. , Petroleum hydrocarbon resins and rosin resins are preferred. These tackifying resins may be used alone or in combination of two or more. The content of the tackifying resin is usually 0.5 to 3 per 100 parts by weight of the rubber component in the rubber latex.
It is selected in the range of 0 parts by weight. If the content is less than 0.5 part by weight, the effect of imparting tackiness may not be sufficiently exhibited. If the content is more than 30 parts by weight, the effect is not so much improved for the amount. Of the resin may be reduced, and the resin may not be uniformly dispersed. In consideration of the tackifying effect and the dispersibility of the resin, the preferable content of the tackifying resin is in the range of 1 to 20 parts by weight.

In the aqueous cement of the present invention, a nonionic surfactant is usually used as an emulsifier to emulsify and disperse the tackifying resin. Examples of the nonionic surfactant include sorbitan monostearate, sorbitan monooleate, sorbitan monopalmitate, sorbitan tristearate, sorbitan sesquioleate, propylene glycol monostearate, diethylene glycol monostearate, and propylene glycol monostearate. Laurate and the like. The emulsifier does not necessarily need to be added depending on the type and amount of the tackifying resin. In the water-based cement for tires of the present invention, as long as the object of the present invention is not impaired,
If desired, various additives conventionally used in conventional water-based cements for tires, for example, fillers other than carbon black, stearic acid, zinc oxide, vulcanizing agents, vulcanization accelerators and the like can be contained. When using the water-based cement of the present invention to increase the conductivity of the tread,
It is preferable to have a conductivity such that the specific resistance after vulcanizing the unvulcanized tire to which it has been applied is 10 ⁸ Ω · cm or less, particularly 10 ⁷ Ω · cm or less.

The solid content concentration is appropriately selected in consideration of coating properties, dispersion stability, handleability, etc., and is usually in the range of 5 to 50% by weight, preferably 10 to 30% by weight. . The method for preparing the water-based cement for tires of the present invention is not particularly limited, and a conventionally known method, for example, a rubber latex, carbon black, a tackifying resin and various additives optionally used are mixed at a predetermined ratio. Further, if necessary, water is added, and the resultant is homogenized and dispersed uniformly using a homogenizer or the like, whereby a desired aqueous cement can be prepared. The water-based tire cement thus obtained is applied to the surface of an unvulcanized tire tread and vulcanized to obtain a tire tread with conductivity. In addition, in addition to the above-mentioned applications, this water-based cement is also used as a so-called splice cement applied to a joint portion of a tire tread, so as to impart conductivity to the inside of the tread from the tire tread surface to the base (belt). Can be used as a conductive layer to be inserted into the substrate, or as a cement applied for bonding between members, such as a tread under cement.

[0010]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 SBR latex [trade name: JSR2, manufactured by JSR Corporation]
108], 100 parts by weight of rubber component, carbon black [N234, manufactured by Tokai Carbon Co., Ltd., nitrogen adsorption specific surface area 131 m ² / g, dibutyl phthalate oil absorption 123
ml / 100 g], 50 parts by weight, C ₉ petroleum resin [manufactured by Nippon Petrochemical Co., Ltd., trade name: Neopolymer 80] 0.5 parts by weight, and a nonionic surfactant [manufactured by Dainippon Ink and Chemicals, Inc.] , Trade name: Nonion NS210] 3 parts by weight were added and sufficiently stirred with a tabletop homogenizer to prepare an aqueous cement having a solid content concentration of 20% by weight. Examples 2 to 4 Water-based cements were prepared in the same manner as in Example 1 except that the amount of C ₉ petroleum resin was changed as shown in Table 1.

Comparative Example 1 A water-based cement was prepared in the same manner as in Example 1, except that C ₉ petroleum resin was not used. For the aqueous cements obtained in Examples 1 to 4 and Comparative Example 1, the unvulcanized rubber adhesiveness, the vulcanized rubber adhesiveness, and the specific resistance of the cement-applied vulcanized rubber were determined as follows. Table 1 shows the results. (1) Unvulcanized Rubber Adhesion After a rubber composition for a tread having the composition shown in Table 2 was prepared, two sheets having a length of 100 mm, a width of 20 mm, and a thickness of 5 mm were prepared. Then, an aqueous cement was applied to the adhesive surface of each of these sheets, and the thickness of the adhesive layer after drying was 100 μm.
m and bonded together, and dried to prepare a cement-coated unvulcanized sample. The unvulcanized sample to which the cement was applied was subjected to a peeling test using a strograph, and the adhesion was evaluated according to the following criteria. ：: Peel strength of 1 kgf / cm or more △: Peel strength of 0.4 kgf / cm or more, 1 kgf / cm
Less than ×: less than 0.4 kgf / cm

(2) Vulcanized Rubber Adhesion A cement-coated unvulcanized sample was prepared in the same manner as in (1) above, and then vulcanized at 160 ° C. for 17 minutes to prepare a cement-coated vulcanized sample. The vulcanized rubber sheet coated with cement was subjected to a peeling test using a strograph, and the adhesiveness was evaluated according to the following criteria. ：: Peel strength of 10 kgf / cm or more △: 5 kgf / cm or more and less than 10 kgf / cm ×: less than 5 kgf / cm (3) Specific resistance of vulcanized rubber coated with cement Cement coated and prepared in the same manner as in (2) above The specific resistance of the vulcanized rubber sheet was measured according to the following method. A disk-shaped sample having a radius of r = 2.5 cm and a thickness of t = 0.2 cm was prepared, and its electric resistance R was measured using an insulation resistance test box manufactured by Advance Corporation shown in FIG. The specific resistance ρ was calculated by the following equation. In the figure, 11 is a sample, 12 is a main electrode, 13 is a guard electrode, and 14 is a counter electrode. ρ = (πr ² / t) R

[0013]

[Table 1]

[0014]

[Table 2]

[Note] SBR # 1500: Styrene-butadiene rubber, JS
BR01 manufactured by R Co., Ltd .: polybutadiene rubber, 6PPD manufactured by JSR Co., Ltd .: anti-aging agent, N-phenyl-N ′-(1,
3-dimethylbutyl) -p-phenylenediamine X50S: Silane coupling agent, manufactured by Degussa AG CBS: Vulcanization accelerator, N-cyclohexyl-2-benzothiazylsulfenamide DPG: Vulcanization accelerator, diphenylguanidine

[0016]

The water-based cement for tires of the present invention does not use an organic solvent, so that the working environment is not deteriorated, and the poor adhesion of the conventional water-based cement to the unvulcanized tire member is reduced. It has improved and good adhesion to unvulcanized tire components.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for measuring an electric resistance R of a disk-shaped sample.

Claims (4)

[Claims] 1. An aqueous cement containing a rubber latex and carbon black, wherein the carbon black has a nitrogen adsorption specific surface area of 60 to 200 [m ² / g] and a dibutyl phthalate oil absorption of 60 to 180 [ml / 100].
g], and further comprising a tackifier resin. 2. The water-based cement for a tire according to claim 1, wherein the tackifier resin is at least one selected from a coumarone-indene resin, a phenol-terpene resin, a petroleum hydrocarbon resin and a rosin resin. 3. The aqueous cement for tires according to claim 1, wherein the content of the tackifier resin is 0.2 to 30 parts by weight per 100 parts by weight of the rubber component in the rubber latex. 4. The water-based cement for a tire according to claim 1, wherein the content of carbon black is 40 to 60 parts by weight per 100 parts by weight of the rubber component in the rubber latex.