DE2424533A1 - METHOD FOR REDUCING THE STICKNESS OF RUBBER DURING MANUFACTURING - Google Patents

Description

Dr.-1 ng. E. BERKENFELD · Dipl.-Ing. H. BERKENFELD, patent attorneys, Cologne Attachment file number

for entering ^ ^ _- . J ₉₇₄ "^ Name of the note _{RUßBER &} PLASTICS RESEARCH

ASSOCIATION OF GREAT BRITAIN R 96/2

Method of reducing the stickiness of rubber during the Manufacturing.

The invention relates to the handling of rubber compounds during the manufacturing process. Under the name "Rubber" is understood to mean both natural and synthetic rubber which are in a similar state during the process find that they are trying to attach to themselves and to other materials.

It is therefore an object of the invention to temporarily reduce this tendency to stick, known as "stickiness" or eliminate it until it is permanently removed by the chemical change in rubber known as vulcanization. It it is known that this tackiness can be prevented by the application of a dusty agent such as talc can. The known powdery agents have certain disadvantages that is, they cannot be easily removed from the surface of the product or they may discolor the product.

According to the invention, a water-soluble powdery agent is used applied to the surface of the rubber to temporarily remove the stickiness. This powdery agent can be removed at some later stage in the process by washing with water removed, either before vulcanization to restore tack, if desired, or after vulcanization, when the tackiness is permanently removed by crosslinking the material.

The rod-shaped means is preferably a water-soluble material of fairly uniformly fine particle size, which is so has been processed that there is an appropriate particle size distribution by mechanical grinding, precipitation or any has another appropriate procedure. The particle size is

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preferably less than 0.2 mm. Preferably this is dusty Means for the rubber also chemically inert.

A preferred powdery agent is sodium bicarbonate, however other water-soluble inorganic salts such as sodium carbonate or sodium chloride can also be used. Under Using a stickiness meter (according to British Patent 741 214) it was found that sodium bicarbonate in the Tack reduction is generally as effective as talc.

The powdery agent can consist of a mixture of two or more water-soluble materials. Other materials can be added to help achieve a particle size distribution that is fine enough to enable the function of the to improve powdery agent or to reduce adverse effects on the processing device, such as a corrosion stabilizer. Magnesium carbonate can be added to sodium chloride in small amounts to allow it to flow freely to support the same.

The powdery agent can be applied to the rubber surface by means of a Device are applied which entrains the particles of the powdery agent in a gas flow, as in the British Patent specification 027 103 and 1 134 069 is described, or by any other equivalent facility.

When processing the rubber the heating of the same in one Comprises fluidized bed, the powdery agent can be applied to the rubber, such as a rubber molding, before the rubber enters the bed. The powdery agent not only facilitates the separation of the rubber from itself, but also reduces the sticking of the balls or another Material of the fluidized bed on the rubber and facilitates the subsequent removal of the balls from the rubber and restoration of the original color of the rubber product.

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The following is an exemplary embodiment of the invention described in more detail with reference to the drawings in which:

Figure 1: schematically the front view of a device for carrying out the method according to the invention and

FIG. 2: a detail of the head of the one shown in FIG Powder dispenser.

The device shown in FIG. 1 generally consists of four units lying one behind the other, namely an extrusion unit 3, a fluidized bed unit 4, a water bath ^a unit 5 and a take-off unit 6.

The extruder 3 is a cold flow rubber extruder from Shaw-Davy, which has a transverse head 7 in which a. Press die 8 is fitted and in the same by a retaining ring 9 is attached (Figure 2). A powder distributor or a dusting unit 10 (FIG. 1) is attached to the extruder 3, which connected to a distribution head 12 by air distribution pipes 11 is. As FIG. 2 shows, the distributor head 12 consists of the ring 9 and an aluminum hood 13 carried by the ring. The pipes 11 continue as bores 14 within the ring 9. The bores 14 end at the press die 8 in order to distribute the powdery agent from the powder distributor 10 on the surface of the rubber press piece 15 when the same leaves the die 8. That Dust-like agent is distributed from the bores 14 by an air flow, which entrains the dust-like agent will. A suction pipe 16 is attached to the hood 13 in order to remove excess dusty agent from the hood. Further details of the sputtering unit can be found in the UK patent 1 027 103.

From the distributor head 12, the pressed piece 15 passes into the fluidized bed unit 4, in which the same through a bed of flowed and heated beads 17 passes therethrough. White

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The more detailed details of the fluidized bed unit are those of the British Patent specification 906 139 can be found. The vulcanized rubber molding 15 passes through the water tank 18 of the water bath unit through, in which the same rests on the surface of the water, is scrubbed by brushes 19 to remove adhering beads to remove, and is sprayed with water jets 20 to dissolve the water-soluble powdery agent. The movement of the Pressing by the units 4 and 5 is effected by the drawing unit 6.

When using the device shown in the drawings an amount of the M14 SBR compound (styrene-butadiene rubber) is prepared for extrusion and is charged into the extrusion unit 3. It has the following composition:

Parts by weight

SBR 1500 100.0

Carbon black 75.0

Zinc oxide 5.0

Stearic acid 3.0

Flectol H (antioxidant

middle),

e.g. polymerized 1,2-dihydro-

2,2,4-trimethylquinoline 1.0

Stantoflex 13 (antiozone agent),

e.g. N-phenyl-N '- (1,3-dimethylbutyl) -

p-phenylenediamine 1.0

aromatic oil 15.0

Santocure CBS (accelerator), e.g. N-cyclohexyl-2-benzthiazole sulphenamide 1.0

Diphenyl guanidine (accelerator) 0.5

Sulfur 2.5

About 4 kg of the powdery product "Soludal" (finely ground Sodium bicarbonate) are poured into the powder dispenser 10 and Applied in an air flow to the surface of the pressing piece 15 as soon as the same leaves the die 8. A fine coat

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the sodium bicarbonate powder is in this way on the Pressstiik applied before it is immersed in the bed of flowed beads 17.

After passing through the fluidized bed unit 4, the Pressing piece then passed through the water tank 18, which is provided with spray nozzles 20 and cleaning brushes 19 / is. As a result of the protective powder coating only a relatively small amount of globules adhered to the surface when leaving the bed of the pressed piece. These were successfully removed in the water container, in which the powder completely dissolved, while the water jets and brushes removed any remaining globules. The cured compact had a good, black in appearance with no trace of globules or dusty forms Middle.

The method according to the invention is very generally uncured Rubber applicable. Instead of the above-mentioned SBR connection, other rubber connections can therefore be used, such as for Example N203 B butyl N 205 A EPDM (ethylene propylene diene monomer), N 203 C nitrile, N 50 C isoprene, M 241 neoprene rubber and N 170 D natural rubber.

The power of "Soludal" (powdered sodium bicarbonate) as a water-soluble powdery agent is illustrated by the following tack test. A sample of the uncured normal SBR 1712 compound (aged) was used for tackiness Tested on the stickiness meter according to British patent specification 741 and the results were as follows:

Stickiness before dusting 600 g

Stickiness after dusting with "Soludal" zero

Stickiness after washing off

"Soludal" 540 g ..

PATENT CLAIM 409850/0840

Claims (12)

Dr.-lng. E. BERKENFELD · Dipl.-Ing. H. BERKENFELD, patent attorneys, Cologne Annex 2Ο.Μα1 1974 mv // file number »R input« » ^CU * ^ ^{1 13 /} * W Na _me d. Ann ,. RUBBER & PLASTICS RESEARCH ASSOCIATION OF GREAT BRITAIN R 96/2 PATENT CLAIMS Method for reducing the stickiness of rubber during manufacture, characterized in that a water-soluble powdery agent is applied to the surface of the unvulcanized rubber. 2. The method according to claim 1, characterized in that the The surface of the rubber is washed off with water to remove the water-soluble powdery agent. 3. The method according to claim 2, characterized in that the rubber is vulcanized before washing, 4. The method according to claim 3, characterized in that the rubber is vulcanized by heating in a bed of flow-made particles and that the powdery agent on the Gum is applied before entering the bed. 5. The method according to claim 4, characterized in that the rubber consists of a rubber molding. 6. The method according to claim 4 or 5, characterized in that any particles of the bed adhering to the vulcanized rubber are removed. 7. The method according to any one of claims 1-6, characterized in that the powdery agent is applied to the rubber in a gas flow. 8. The method according to any one of the preceding claims, characterized gekennzeich.net that the powdery agent has a particle size that is smaller than 0.2 mm. 409850 / 084Q 9. The method according to any one of the preceding claims, characterized in that the dusty agent is a water-soluble one is an inorganic salt that is chemically inert to the rubber. 10. The method according to claim 9, characterized in that the Salt is sodium bicarbonate. 11. The method according to claim 9, characterized in that the Salt is sodium chloride. 12. The method according to claim 11 »characterized in that the Sodium chloride contains a small amount of magnesium carbonate. 409850/0840