JPS5838735A - Sealant composition for preventing puncture - Google Patents

Abstract

PURPOSE:To titled composition, consisting of a liquid rubber-like polymer having carboxyl groups, liquid rubber-like polymer having no functional group and a tetraalkyl titanate, and having suitable sealing property without giving a bad influence on the physical properties of the rubber-like polymers, e.g. in a tire. CONSTITUTION:A sealant composition obtained by mixing a composition containing (A) a liquid rubber-like polymer having 2-15 carboxyl groups as functional groups in one molecule, e.g. liquid isoprene rubber or liquid butadiene rubber and (B) a liquid rubber-like polymer having no functional group with 1-20wt%, based on the weight of the component (A), tetraalkyl titanate, preferably having 3-8C alkyl groups, e.g. tetra-n-butyl titanate as a crosslinking agent. The resultant composition is capable of easily forming a puncture preventing layer on the inner surface of a tire, maintaining the suitable tackiness and strength, and producing little change with time for a long term without causing the deviation in running.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a non-migratory composition that does not adversely affect the physical properties of tire rubber, and can effectively form a bank prevention layer on the inner surface of a tire, and can last for a long time. There is little daily variation,
This is a tire puncture prevention sealant composition that maintains suitable viscosity and strength and has suitable puncture ability without shifting during running.

Conventionally, this type of sealant consists of a solid rubbery polymer, a liquid rubbery low-molecular polymer, a tackifier,
Selectively mix softeners, plasticizers, etc. to reduce unevenness during high-speed driving,
In order to prevent the flow phenomenon, an inorganic photonic agent or a crosslinking agent, or an inorganic photonic agent and a crosslinking agent are blended to adjust the balance between the adhesiveness and stickiness of the sealant and its strength. The vulcanizing agent and crosslinking agent used are sulfur, baroxide, quinone dioxime, etc., which are usually used in general rubber.

Therefore, in the conventional method, softeners, plasticizers, etc. are undesirable because they affect the physical properties of the tire due to their migration properties, and in order to prevent unevenness using an inorganic filler, a large amount of inorganic filler must be mixed. and the adhesion and strength will decrease,
Furthermore, when sulfur is used as a crosslinking agent, oral changes occur, and the sealant becomes hard, resulting in a decrease in the inhibition ability.

Further, the use of peroxide or quinone dioxime as a crosslinking agent is subject to restrictions in terms of handling and use.

Note that the above crosslinking method requires a crosslinking reaction at high temperatures, so it is necessary to add an extra step of temperature control to form a sealant on the tire and cause the crosslinking reaction. However, it was found that the tires had a negative thermal effect on the tires.

Therefore, the inventors aimed to eliminate all of the above-mentioned factors that caused problems with conventional sealants, and eliminated migratory additives and sulfur materials that impair the physical properties of tires, and The purpose of this study was to find a tire puncture prevention sealant composition that would stop the crosslinking reaction at low temperatures and exhibit a particularly stable stopping ability over a long period of time.

That is, the puncture prevention sealant composition of this invention
The crosslinking agent used is tetraalkyl titanate, which does not affect the comb quality that makes up the tire.
This sealant composition is a tire puncture prevention sealant composition in which a mixture containing a one-component rubbery polymer having a carboxyl group as a functional group and a liquid rubbery polymer having no functional group is cross-linked with a tetraalkyl nathanate. The main ingredient is adhesive, as well as other adhesives as necessary.
A reinforcing agent is appropriately added.

The tetraalkyl titanate used as a crosslinking agent has the following structural formula.

However, R: alkyl group, n=1 to 10 The above-mentioned crosslinking agent acts on the carboxyl group of the rubbery polymer to generate ROH'jz and crosslink it. When the alkyl group has 3 to 8 carbon atoms, it is highly reactive and reacts easily at room temperature, but when the carbon number exceeds 8, it becomes difficult to react. On the other hand, if it is less than 3, the reaction is too fast and it is difficult to use it. In addition, as the tetraalkyl titanate, tetra-! where the alkyl group has 3 carbon atoms! -Propyl titanate and 4 carbon atoms
Tetra-n,-butyl titanate is exemplified, and in addition,
As an example of the gradual decrease in reactivity with increasing carbon content,
An example of unsuitable tetrastearyl titanate having 17 carbon atoms is given.

Liquid rubbery polymers having a carboxyl group as a functional group include liquid isoprene rubber, liquid butadiene rubber, liquid chloroprene rubber, etc. The number of functional groups of the carboxyl group is preferably 2 to 1.

In addition, as a liquid rubbery polymer without functional groups,
There are liquid imprene rubber, liquid butadiene rubber, liquid polybutene, liquid polyisobutylene, liquid isobutylene/isoprene rubber, liquid ethylene/propylene/diene monomer, etc.

Next, embodiments of the present invention will be specifically explained in Examples.

An example of the sealant composition of this invention is shown in Table 1.

Table 1 Parts by weight (Note) -coo birch 1. R(3)...Bracket 3 indicates the number of carboxyl groups per molecule of polymer, which is a liquid isoprene rubber having three carboxyl groups.

-COOH liquid isoprene rubber (10...Similarly, a liquid isoprene rubber having a carboxyl group of 10.

-QOOH liquid BR (21... liquid butadiene rubber having 2 carboxyl groups).

1*, 4* (n='?)...A tetra-n-butyl titanate crosslinking agent is used when n=7 in the structural formula of a tetraalkyl titanate.

2*, 3* (n=1): A tetra-n-butyl titanate crosslinking agent where n==1 in the structural formula of tetraalkyl titanate is used.

The above composition was sprayed onto the inner surface of the tread and part of the shoulder of a tire size 165-8 R-13, and the dynamic performance test, diurnal change test, and static sealing test ( The pricking properties were observed at room temperature, low temperature, and after aging.

Dynamic performance is determined by tire internal pressure 1. 'i' II/cnt represents the uneven state of the sealant after rotating at a speed of 168A1i/h for 30 minutes in a drum testing machine, and the static sealing performance is determined by the internal pressure of 1. 't kf//c
For Tit tires, at room temperature, 30 nails of four types with needle diameters of 2.4 mm, 3.1 mm, 3.8 mm, and 4.5 mm are driven into the tire, and immediately pulled out. This is a test of tire sealing performance.

In the case of low temperature, the individual fixing ability was tested at -10℃, and 50 leopards of two types of fj nail diameter, 4. This is an observation of the sealing performance of the tire.

In the aging test, the sealant was aged in air at 80°C for 10 days and the condition of the sealant was observed.

Static sealing test after aging
．． Holding the tire at 7 k'i/cfA, 50 nails of two types, each with a needle diameter of 2.4 mm and a needle diameter of 4 and 5 ten, were driven into the tire, and the tires were immediately pulled out to observe the shearability of the tire. It is something.

The above observation results are shown in Table 2 below.

Table 2 (Note) 100% OK: All nails are completely sealed.

Tables 1 and 2 above exemplify the bank prevention sealant composition of the present invention and the results of its discrimination ability test.

The following Tables 3 and 4 show that when the requirements of the sealant composition of the present invention are fully satisfied, that is, when the amount of the tetraalkyl titanate crosslinking agent is too much or too little, and when the number of alkyl groups is large, In the case of conventional sulfur crosslinking, individual sealant ability tests were conducted on sealant compositions with a large number of carboxyl groups.

This sealant composition is shown in Table 3 below.

Table 3 (Note) -COOH liquid IRIi...Liquid isoprene rubber with 20 carboxyl groups 5*, 6* (n=7)...Tetodi when n='i' in the structural formula of tetraalkyl titanate -n-butylnathanate crosslinking agent is used.

No. 7* (n=1): A tetra-ter-n-butyl titanate crosslinking agent is used when n=1 in the structural formula of a tetraalkyl titanate.

Regarding the above sealant composition, a sealant layer was formed on a tire size 1.65-8R-13 in the same manner as in Table 1, and the same tests as in Table 2 were conducted. The results are shown in Table 4. .

Table 4 (Note) χ/3 Q OK, χ1500K (χ indicates the number of each numerator)...Numerator χ indicates that only χ of 30 and 50 driven nails are sealed. The number of air leaks is (30-x) and (50-τ).

As shown in Tables 3 and 4 above, sample shop 5 was tested when the tetraalkyl titanate crosslinking agent had M it % of 07 for the carboxyl group-containing polymer, and due to insufficient crosslinking, Occasionally, considerable deviation occurs, and the sealing performance is partially degraded.

In sample shop 6, the weight ratio of the tetraalkyl titanate crosslinking agent was 21.7, and due to excess, the sealant became harder than necessary and the sealing performance was greatly reduced.

Therefore, crosslinking agents for carboxyl group-containing polymers (
The weight percentage of tetraalkyl titanate is more than 20%.
It is necessary to set it in the following range. If it exceeds 20 inches, the sealant will harden too much and lose its puncture prevention effect.
If it is less than 1%, the sealant will not be sufficiently cured and will cause unevenness during high-speed running. Therefore, the most preferable thn range is 2 to 15% by weight and 1t%.

Sample A7 has a functional group in which the number of carboxyl groups is zO per polymer molecule, and when the number of carboxyl groups is large in this way, reaction with the tetraalkyl titanate causes small particulate kelization, and some parts of the carboxyl group are formed during high-speed running. This causes deviation and poor sealing performance, especially for large-diameter nails. Therefore, the number of carboxyl groups is in the range of 20 or less, particularly preferably in the range of 2 to 15 as shown in Tables 1 and 3, and if it is less than 2, the strength will be insufficient.

Sample report 8 is an example of using detrastearyl titanate, in which the alkyl group of tetraalkyl titanate has 17 carbon atoms, and because it has a large number of carbon atoms and has low reactivity, it causes considerable deviation during high-speed running. do. Therefore, the sealing performance especially for large-diameter nails is also poor.

Therefore, as mentioned in the reactivity of the crosslinking agent,
The number of carbon atoms in the alkyl group is suitably in the range of 3 to 8; if it is less than 3, the reaction is too rapid and it is difficult to use.

In addition, sample shop 9 is an example of a conventional sulfur-cured sealant, and as shown in Table 4, the dynamic performance and static sealing performance (room temperature, low temperature) are good, but the sulfur-vulcanized sealant is good. Sulfur-based sealants have poor aging properties, and the sealant hardens over time, so the static sealing properties after aging are considerably reduced.

However, the sealant composition of this invention is
As shown in the table, the dynamic performance is stable, outside at room temperature,
It provides perfect static sealing performance both at low temperatures and after aging.

In addition, the blended composition of this invention in which a tetraalkyl titanate is used in a mixture containing a liquid rubbery polymer having a carbothousyl group as a functional group and a liquid rubbery polymer having no functional group exhibits iA adhesiveness. It is a composition suitable for use as a gel sealant, and because it undergoes an appropriate crosslinking reaction at room temperature, it is possible to mold the sealant onto a tire without causing any adverse thermal effects on the vulcanized tire.

Furthermore, this tetraalkyl titanate is multidimensionally crosslinked, and by adjusting the degree of crosslinking, a suitable rubber-like polymer that does not cause deviation during high-speed running can be formed.

In addition, the tetraalkyl titanate remaining from the crosslinking reaction reacts with moisture in the air to form physically and chemically stable titanium oxide on the sealant surface layer, which prevents the interior of the sealant from changing over time.

Furthermore, in order to obtain good sealing performance in a low temperature range, it is preferable to use a polymer with a low glass transition point (M). Furthermore, in terms of compatibility, it is preferable to select '+/J'ff: which have mutually close solubility parameter values.

In addition, the method of molding the sealant into the tire is as follows in the example:
Although an example was shown in which it was formed by a spray method, it is also possible to form it into a plate shape in advance and attach it.

As described above, the puncture prevention sealant composition of the present invention has excellent dynamic performance and little oral change, and also has excellent static sealing properties at room temperature, low temperature, and after aging, and remains unchanged over a long period of time. This is a unique composition that exhibits excellent sealing properties.

Agent: Patent Attorney Naho Oshima

Claims (3)

[Claims] (1) A tetraalkyl titanate is added to a mixture containing a liquid rubbery polymer having a carboxyl group as a functional group and the number of functional groups per molecule of the polymer is 2 to 15, and a liquid comb-like polymer having no functional group. A tire puncture prevention sealant composition characterized in that it is used in an amount of 1 to 2 ON of a liquid comb-like polymer car body having a base. (2) A watch in which the liquid rubbery polymer having a carboxyl group as a functional group is liquid isoprene rubber, liquid butadiene rubber, or liquid chloroprene rubber.
The tire puncture prevention sealant composition described in Section 1. (3) The tire puncture prevention sealant composition according to claim 1, wherein the alkyl group of the tetraalkyl titanate has 3 to B carbon atoms.