DD144890A5 - AIR TIRES WITH A LAYER OF A SELF-SEALING MATERIAL - Google Patents

Abstract

The invention aims to develop pneumatic tires in which damage areas are more reliably sealed automatically, even with extended tire use, using an elastomer-based sealing material. The pneumatic tire according to the invention has an inner wall provided with a layer of a self-sealing material, which, viewed radially inward, is covered by a layer of vulcanized elastomer mixture. The base of the sealing material layer is at least one low-molecular-weight elastomer mixed with at least one thermosetting resin, and at least one crosslinking or curing agent is kept isolated therefrom.

Description

Berlin, _{October 25, 1979 Λ} · _ή * 'APB 60 0/214 403 \ 4 403. -1- ₅₅₉ 32/26

Pneumatic tire with a layer of self-sealing material

Field of application of the invention

The invention relates to pneumatic tires, the inner wall of which is wholly or partly provided with a lining of a layer of self-sealing material, which is covered radially inwardly by a layer of vulcanized elastomeric mixture. The puncture of this lining is to close as soon as possible a point of damage in the tire by flowing the sealant into the point of damage.

Characteristic of the known technical solutions

From studies and experiments, a composite liner has been developed in which a crosslinkable sealant-containing layer is adjacent to a layer containing a crosslinking agent of this sealant, the two layers being separated from each other by a layer of vulcanized elastomeric mixture are. In addition, the substances forming the sealing and crosslinking layers have such viscosities that the substances can flow into the damaged area under the action of the escaping air and definitively close them. This prevents dismantling of the tire and the use of a mechanic.

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However, a system consisting of a layer of sealing material and a dispersion of cross-linking material in the cavity of the tire has also been developed which may also incorporate this cross-linking agent into a lubricant which will damage it of the pneumatic tire when it is running under a lower pressure than the normal inflation pressure, or the crosslinking agent may be at least partly in the form of an envelope on very light granular particles intended to assist the tire in the pail of a pressure drop.

Object of the invention

By means of the invention, pneumatic tires are to be developed, in which a more secure sealing of damaged areas occurs automatically.

Explanation of the essence of the invention .

It is an object of the invention, when using an elastomer-based sealing material, to replace the usual crosslinking or vulcanizing agents with agents that do not lose effectiveness during use of the pneumatic tire.

The pneumatic tire according to the invention has an inner wall which is, wholly or partly provided with a lining of a layer of self-sealing material, which is covered radially inwardly by a layer of a vulcanized elastomeric mixture, and the base of the layer of sealing Material at least

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is a low molecular weight elastomer having a molecular weight of preferably less than 30,000, mixed with at least one thermosetting resin, and that at least one thermosetting resin crosslinking or curing agent is isolated from the sealing material by means of the vulcanized elastomeric mixture layer.

Preferably, a sealing mixture is used, the

actual viscosity at 60 ⁰ C, measured with the

4- T

Rheogoniometer from Weissenberg, between 10 and 10 H / s / m

-2

for a shear rate (speed gradient) of 10 to 10 s ~. This viscosity is preferably adjusted by adding a powdery granular (particle size less than 250 / um) and / or fibrous (fiber length at least 0.5 mm with a diameter between 0.005 and 0.040 mm) filling.

The epoxy resins derived from the diglycidyl ether of bis-phenol A, for example EPOIT 828 from Societe Shell, have proved to be very suitable owing to their reaction rate, in which case the curing agents are preferably chosen from amines in combination with lactones, eg HY 977 from Ciba (cf. Diaminodiphenylmethane with f -butyrolactone)

The use of catalysts, e.g. the half-esters or the aminophenols, allows for an acceleration of crosslinking.

As low temperature crosslinkable resins, the polyurethanes and the polyesters can be used. The polyurethanes suitable for the invention are obtained by

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Veriasing a saturated dihydroxylated oligomer with a crosslinking agent, a catalyst and a diisocyanate; Polyisobutylene is used as the matrix for these constituents.

Particularly suitable for carrying out the process are the dihydroxylated polyethers (polytetrahydrofuran, polyethylene oxide, polypropylene oxide), the dihydroxylated polyesters (polyadipates, polyazelates, polysuccinates of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol) and mixtures thereof is preferably a triol, in particular glycerol, or trimethylolpropane. The catalyst used may be diazobicyclooctane, a metal triacetylacetonate, tin octoate or a mercury salt. Among the diisocyanates are the low-volatile 4,4'-diisocyanatodiphenyl-methane (IvIDI) and isophorene diisocyanate.

Among the polyesters, the derivatives of methacrylic acid in combination with peroxides give satisfactory results.

Furthermore, according to the invention, the curing agent can be assigned to a liquid catalyst.

Catalyst can be a half ester or an aminophenol.

Further, it is possible for the sealing layer to comprise a crosslinking layer of a low molecular weight elastomer blended with at least one curing agent and optionally a catalyst for the thermosetting resin contained in the sealing layer,

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is adjacent, wherein this crosslinking layer is separated from the sealing layer by a layer of a vulcanized elastomer mixture ·

Furthermore, it is possible according to the invention that at least one curing agent and optionally a liquid catalyst for the thermosetting resin contained in the sealing layer in the cavity of the pneumatic tire by atomization or by incorporation in a lubricant either in the form of a coating of granular particles or very light egg globules are dispersed.

Ausführun ^ SExample

The invention will be explained below in several embodiments.

example 1

The self-sealing inner lining is composed of two layers separated by a layer of vulcanised rubber.

The composition of the layer of the sealing compound is as follows (in% by weight):

High Molecular Weight Elastomer: Polyisobutylene 41.6 Filling: Dusty powder of vulcanized

Rubber 40.3

Resin: Epon 828 Shell (from the diglycidyl ether of

bis-phenol A obtained epoxy resin) 18,1

§14403

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The composition of the layer of the crosslinking mixture is the following (in% by weight):

Polyisobutylene 37.8

Pouring: dusty powder of vulcanised

Rubber 44 »9

Curing agent: HY 977 Ciba (Diaminodiphenyl-

methane) 16.5

Catalyst: DY 060 Ciba (half ester of

Maleic acid) 0.8

Example 2

The inner lining is simple and consists of a layer of cross-linkable, sealing compound. This sealing mixture contains (in% by weight):

Low molecular weight elastomer: polyisobutylene 42.4. Pour: MT / NS 55.6

Resin: Epon 828 Shell (from the diglycidyl ether of bis-phenol A derived epoxy); 2.0

The curing agent is diethylenetriamine contained in a lubricant in an amount of 7.5% by weight; the lubricant may e.g. have the following composition (in% by weight):

Silicone emulsion 65

Synthetic oil based on polyglycol ethers 5 '

Ethanol. 30

Quaternary iuranonium (alkyldimethylbenzylammonium chloride). 300 ppm

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Diethylenetriamine 715

According to the invention, this lubricant may be either in powdery or liquid state in the cavity of the tire either as a coating of granular particles, as described in DE-OS 24 60 253, or as beads, as described in DE-OS'en 25 01 188 and 25 49 239 are used.

Example 3

Crosslinkable mixture (in Gevi,%) :

Polyisobutylene (molecular weight 15,000) 72,54

Polyisobutylene (molecular weight 2,000) 18,14 polyadipate of ethylene glycol and propylene

glycol (molecular weight 2,800) 9,10

Glycerine · 0.18

Diazobicyclooctane 0.04

Crosslinking mixture:

Polyisobutylene (molecular weight 15,000) 67.8 Polyisobutylene (molecular weight 2,000) 16,9,4,4'-diisocyanatodiphenylmethane 15 # 3

After damage, pneumatic tires provided with self-sealing layers according to the invention showed daily use even after several months of use. Use no noticeable pressure loss.

Claims (9)

A pneumatic tire, the inner wall of which is wholly or partially provided with a lining of a layer of self-sealing material which is radially inwardly covered by a layer of vulcanized elastomeric mixture, characterized in that the base of the layer of sealing material is at least is a low molecular weight elastomer, preferably having a molecular weight below 30,000, mixed with at least one thermosetting resin, and that at least one curing or curing agent for the thermosetting resin is isolated from the sealing material by means of the vulcanized elastomer blend layer; 2. Pneumatic tire according to item 1, characterized in that the sealing material has an actual viscosity at 60 ° C., measured with the Rheogoniometer from Weissensee. Pneumatic tire according to item 2, characterized in that the actual viscosity of the sealing material is determined by means of a powdery, granular (particle size less than 250 / μm) and / or fibrous (length of the fibers at least 0.5 mm for a diameter between 0.005 and 0.040 mm ) Filling is set · 214 403 -9- 25.10.1979 AP B 60 C / 214 55 932/26 4. A pneumatic tire according to item 1, characterized in that the resin / resin-curable resin is an epoxy resin derived from the diglycidyl ether of bis-phenol A and the curing agent is an amine in combination with a lactone, 4- 1 2 berg, between 10 ^ and 10 11 / s / m for a shear rate from 10 ~ ² to 10 ° s " ¹ . 5. A pneumatic tire according to claim 1, characterized in that the thermosetting resin is a polyurethane, which was obtained in a conventional manner by mixing a saturated, dihydroxylated oligomer with a crosslinking agent, a catalyst and a diisocyanate, said components in a Matrix of polyisobutylene are included » 6. Pneumatic tire according to item 1, characterized eiceline t by the fact that the curing agent is assigned to a liquid catalyst · 7. A pneumatic tire according to item 6, characterized in that the catalyst is a half ester or an aminophenol. 8. A pneumatic tire according to any one of items 1, 2, 3 and 6, characterized in that the sealing layer comprises a crosslinking layer of a low molecular weight elastomer blended with at least one curing agent and optionally a catalyst for that contained in the sealing layer thermosetting resin is adjacent, wherein said crosslinking layer is separated from the sealing layer by a layer of a vulcanized elastomeric mixture. 214403 -10- '25.10.1979 AP B 60 C / 214 403 55 932/26 -8- 25.10.1979 AP B 60 C / 214 55 932/26 invention claim Pneumatic tire according to any one of items 1, 2, 3 and 6, characterized in that at least one curing agent and, optionally, a liquid catalyst for the thermosetting resin contained in the sealing layer in the cavity of the pneumatic tire by atomization or by incorporation into a lubricant either in the form of a coating of granular particles or of very light globules.