GB2071113A

GB2071113A - Production of a rubber solution

Info

Publication number: GB2071113A
Application number: GB8107347A
Authority: GB
Original assignee: METZLELER KAUTSCHUK GmbH
Current assignee: METZLELER KAUTSCHUK GmbH
Priority date: 1980-03-11
Filing date: 1981-03-09
Publication date: 1981-09-16
Also published as: FR2477956A1; IT1141981B; NO810605L; DE3009271C2; DE3009271A1; IT8119792A0; GB2071113B

Abstract

A rubber solution is produced by the simultaneous grinding of the components of a rubber mixture and solvent in an attritor, a device in which grinding bodies, for example of steatite, and the rubber mixture components and solvent are stirred in a stationary container.

Description

SPECIFICATION Production of a rubber solution This invention relates to a process for the production of rubber solutions from the components of a rubber mixture and a solvent.

Rubber solutions of this type are used, for example, for the production of coated fabrics, e.g. for inflatable boats and air matresses. During this operation, the rubber solution is vulcanised after the fabric has been coated, so that a firm join is produced between the resulting vulcanised rubber and the fabric.

Rubber solutions have hitherto been produced such that prepared mixtures present as batches and batches in the form of granulated material or sheet pieces are dissolved in the solvent using kneader stirring devices or blade stirrers. If it was necessary to reduce the grain size, then other working steps had to be subsequently provided, e.g. friction seats.

Highly-accelerated, temperature-sensitive rubber mixtures could not be processed in this manner due to the relatively high temperatures resulting during this processing operation.

Moreover, complex apparatuses were necessary for the production of the batches or prepared mixtures, such as, for example rubber cleavers, heating chambers, batch kneaders with accessories, ready mixture kneaders with accessories, rolling mills, screening machines and possibly calanders and pre-heating rolling mills. Additives could only be added to a small extent during the dissolving step or by combining two solutions.

Finally, the particle size of the rubber solutions which was achieved in the conventional process was still relatively high, usually not less than 50 ,u. However, to improve the vulcanisation process, the density and the finish, and in general to improve the finished product, as small a particle size as possible is required. However, this could not be achieved by the known process.

According to the invention there is provided a pro cessforthe production of a rubber solution from the components of a rubber mixture and a solvent, wherein the components of the rubber mixture and the solvent are ground in an attritor.

An attritor is a device in which grinding bodies and the material to be ground, i.e. in this case, the components of the rubber mixture and the solvent, are located in a stationary container. The grinding bodies and the quantity of material to be ground are rotated by a stirring device, so that kinetic energy is imparted to the grinding bodies. As a consequence of the resulting beating, rubbing and grinding actions, a very regular distribution of the particles is produced.

A pump system is also generally installed in such an attritor, so that the charge is maintained in constant circulation during the grinding operation.

If required, a temperature control of the material to be ground is also possible.

It has now been found that the use of an attritor of this type produces particle sizes of the order of 10 1, the time required for this purpose being less than in the known process.

The lowest outlay in terms of apparatus for the production of the rubber solution is achieved when the unmixed, conventional components of a rubber mixture and the solvent are directly ground in the attritor. The apparatuses which are necessary for the production of the prepared mixture or the batches and which have been described above are thus no longer necessary, so that the time required is reduced to approximately one third of the time required in the known process. Despite this, grain sizes of approximately 10 ,a may be achieved in a single working step.

As an alternative, so-called prepared mixtures or batches of sheet pieces or granulated material, may be ground in an attritortogetherwith valcanisation accelerators and a solvent. As a result thereof, a substantial simplification is obtained compared to the known process, when relatively small particle sizes, namely particles of the order of approximately 50 1 areto be produced.

Furthermore, highly-accelerated, temperaturesensitive prepared rubber mixtures may be processed by the process according to the invention, as the temperatures resulting in an attritor during the grinding operation are relatively low and do not lead to activation of the prepared mixture.

Additives may also be easily added, if required, to the material to be ground in the attritor at a suitable time.

Although any grinding bodies which are usual for attritors, for example flint or metal balls may be used, steatite balls are used in a preferred embodiment.

Two embodiments of the invention will now be described.

In the first embodiment, the conventional components of a rubber mixture, the vulcanisation accelerators and the solvent are introduced simultaneously or successively into an attitor and are ground to the required grain size of approximately 10 ,zz. If required and if necessary, conventional additives may also be added.

In the second embodiment, batch granulated material or sheet pieces, the vulcanisation accelerators and the solvent are introduced simultaneously or successively into the attritor and are crushed to the required particle size of approximately 10 IL In this case also, additives may be added if required.

According to the particles available hitherto, any materials usually used for the production of rubber solutions may be used. Thus, good results were achieved both with natural rubber as well as with synthetic rubber, for example butyl rubber or chloroprene polymers. No difficulties occurred when using the conventional solvents, for example toluene or petrol.

1. Aprocessforthe productionofa rubbersolution from the components or a rubber mixture and a solvent, wherein the components of the rubber mixture and the solvent are ground in an attritor.

2. A process according to claim 1,wherein a prepared mixture and the solvent are ground in the attrito r.

3. A process according to claim 1 or 2, wherein a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Production of a rubber solution This invention relates to a process for the production of rubber solutions from the components of a rubber mixture and a solvent. Rubber solutions of this type are used, for example, for the production of coated fabrics, e.g. for inflatable boats and air matresses. During this operation, the rubber solution is vulcanised after the fabric has been coated, so that a firm join is produced between the resulting vulcanised rubber and the fabric. Rubber solutions have hitherto been produced such that prepared mixtures present as batches and batches in the form of granulated material or sheet pieces are dissolved in the solvent using kneader stirring devices or blade stirrers. If it was necessary to reduce the grain size, then other working steps had to be subsequently provided, e.g. friction seats. Highly-accelerated, temperature-sensitive rubber mixtures could not be processed in this manner due to the relatively high temperatures resulting during this processing operation. Moreover, complex apparatuses were necessary for the production of the batches or prepared mixtures, such as, for example rubber cleavers, heating chambers, batch kneaders with accessories, ready mixture kneaders with accessories, rolling mills, screening machines and possibly calanders and pre-heating rolling mills. Additives could only be added to a small extent during the dissolving step or by combining two solutions. Finally, the particle size of the rubber solutions which was achieved in the conventional process was still relatively high, usually not less than 50 ,u. However, to improve the vulcanisation process, the density and the finish, and in general to improve the finished product, as small a particle size as possible is required. However, this could not be achieved by the known process. According to the invention there is provided a pro cessforthe production of a rubber solution from the components of a rubber mixture and a solvent, wherein the components of the rubber mixture and the solvent are ground in an attritor. An attritor is a device in which grinding bodies and the material to be ground, i.e. in this case, the components of the rubber mixture and the solvent, are located in a stationary container. The grinding bodies and the quantity of material to be ground are rotated by a stirring device, so that kinetic energy is imparted to the grinding bodies. As a consequence of the resulting beating, rubbing and grinding actions, a very regular distribution of the particles is produced. A pump system is also generally installed in such an attritor, so that the charge is maintained in constant circulation during the grinding operation. If required, a temperature control of the material to be ground is also possible. It has now been found that the use of an attritor of this type produces particle sizes of the order of 10 1, the time required for this purpose being less than in the known process. The lowest outlay in terms of apparatus for the production of the rubber solution is achieved when the unmixed, conventional components of a rubber mixture and the solvent are directly ground in the attritor. The apparatuses which are necessary for the production of the prepared mixture or the batches and which have been described above are thus no longer necessary, so that the time required is reduced to approximately one third of the time required in the known process. Despite this, grain sizes of approximately 10 ,a may be achieved in a single working step. As an alternative, so-called prepared mixtures or batches of sheet pieces or granulated material, may be ground in an attritortogetherwith valcanisation accelerators and a solvent. As a result thereof, a substantial simplification is obtained compared to the known process, when relatively small particle sizes, namely particles of the order of approximately 50 1 areto be produced. Furthermore, highly-accelerated, temperaturesensitive prepared rubber mixtures may be processed by the process according to the invention, as the temperatures resulting in an attritor during the grinding operation are relatively low and do not lead to activation of the prepared mixture. Additives may also be easily added, if required, to the material to be ground in the attritor at a suitable time. Although any grinding bodies which are usual for attritors, for example flint or metal balls may be used, steatite balls are used in a preferred embodiment. Two embodiments of the invention will now be described. In the first embodiment, the conventional components of a rubber mixture, the vulcanisation accelerators and the solvent are introduced simultaneously or successively into an attitor and are ground to the required grain size of approximately 10 ,zz. If required and if necessary, conventional additives may also be added. In the second embodiment, batch granulated material or sheet pieces, the vulcanisation accelerators and the solvent are introduced simultaneously or successively into the attritor and are crushed to the required particle size of approximately 10 IL In this case also, additives may be added if required. According to the particles available hitherto, any materials usually used for the production of rubber solutions may be used. Thus, good results were achieved both with natural rubber as well as with synthetic rubber, for example butyl rubber or chloroprene polymers. No difficulties occurred when using the conventional solvents, for example toluene or petrol. CLAIMS

3. A process according to claim 1 or 2, wherein a vulcanisation accelerator is added d@ring grinding.

4. A process accordin :n of claims 1 to 3, wherein steatite batis are Jsed as grinding bodies.

5. A process acc@@@ing to any one of claims 1 to 4, wher@in the components of the rubber mixture are crushed to a grain size of approximately 10 #