DE1202483B - Process for the production of solid, non-dusting mixtures from vulcanization accelerators and / or antioxidants - Google Patents

Description

Process for the production of solid, non-dusting mixtures Vulcanization accelerators and / or antioxidants Process for rubber vulcanization and preservation and the use of chemicals to modify vulcanization and to prevent oxidation have long been known. However, there have been the use of the usual vulcanization accelerators or antioxidants some difficulties and problems arise that so far have not or only not at all could be partially resolved.

For example, is in operations such as manufacturing and packaging the accelerator and antioxidant solid at ordinary temperature, the Dust generation extremely disadvantageous, namely because of the loss of considerable Amounts of expensive chemicals and because of the high toxicity of these substances. The latter property can lead to skin diseases of the people working with it.

The same problems arise in rubber processing, wherein numerous manipulations are required, such as unpacking, weighing and introduction of the raw materials in the rubber compounds, etc.

It is known to dust solid accelerators and antioxidants by compressing or deforming the chemicals into beads and the like as well as the chemicals with various dedusting agents, e.g. B. hydrocarbon oils, higher fatty acids, casein, gelatin and resinous substances. Such Although methods could generally reduce dust, they did not produce any results fully satisfactory results.

It has also been proposed to use finely divided solid rubber additives with an aqueous dispersion of a saturated polymer of an aliphatic Mixing monoolefins and thereby obtaining these substances in the form of tablets.

Another problem is the poor mechanical strength many solid accelerators and antioxidants. So many of these cluster together Compounds, often together with the substances that have so far been used to reduce dust were used, despite their initial powdery state during storage. The deformed connections also mostly have an unsatisfactory mechanical quality Strength. Are they, as is the case with normal handling and shipping, moved strongly, the large particles disintegrate noticeably, and undesirable ones are formed Amounts of small dusting particles.

Many solid accelerators and antioxidants tend to work too sticking to the machine rollers, with the result that the accelerator does not can be mixed homogeneously into the rubber compound.

The consequence of this is uneven vulcanization. These disadvantages occur above all in rubber parts that are mixed in short-term operations will.

Difficult distribution of solid accelerators and antioxidants in rubber compounds is another problem. The particle size of some Commercial antioxidants and accelerators will undoubtedly work in some cases contributes to the emergence of this difficulty. Even if there are accelerators or antioxidants can be distributed uniformly in the mass, the profitability is due to excessively long work processes with correspondingly high labor and electricity costs and also questioned because of the material losses.

These problems were so urgent that there were many procedures for their solution have been proposed, some of which are inadequate or only partially satisfactory was. So far, no method has become known that provides a simultaneous solution creates all of these problems.

The invention now relates to a method for the production of solid, non-dusting mixtures of vulcanization accelerators and / or solid antioxidants in the form of powders or smaller agglomerates for rubber processing, whereby the mixtures contain liquid polybutene as a dust-binding agent. The inventive The feature of the process is that it is liquid polybutene and or liquid hydrogenated polybutene with molecular weights from 500 to 5000, preferably 750 to 3000, used in an anhydrous state.

The mixtures of accelerators and antioxidants used according to the invention solve the problems identified in an excellent way, because they 1. during the Production and its use in the rubber industry are not dusty; 2. excellent have mechanical strengths in handling and shipping; 3. no noticeable Have a tendency to stick to the rollers; 4. Distribute well in rubber compounds permit.

The polybutenes used in the process of the invention are Polymers or copolymers obtained by polymerizing isobutene or a mixture of isobutene with butene-1 and / or butene-2 have been obtained.

These polybutenes or hydrogenated polybutenes impair the properties the vulcanization accelerator and / or anti-aging agent does not.

On the contrary, they increase the ease and speed of the Incorporation of the accelerator or antioxidant into the rubber compound and thus act as a dispersant.

The amounts of polybutene can be up to 15 percent by weight of the solid Accelerator or antioxidant. It turned out, however, that one Polybutene amount of about 1 to 10 percent by weight is particularly advantageous.

In addition to polybutene and accelerators or antioxidants, if desired, other substances that can be used in rubber technology in the mixtures be included.

The mixtures according to the invention are suitable for any type of rubber processing, such as the manufacture of tires, tubes, mechanical equipment, wire and Cable insulation, footwear, various rubber items, cement or sponge rubber. They can also be easily incorporated into aqueous dispersions, as in the case of foam or manufacture of diving articles.

The mixtures can be in solid form either finely divided, loose, non-dusting powders or mechanically stable, shaped agglomerates processed, in which the individual particles of the active ingredients in very fine form.

Both forms have clear advantages over the corresponding known mixtures.

Solid accelerators or antioxidants, e.g. B. in the Rubber processing commonly used finely divided form, can be polybutene in any way, e.g. B. by squeezing, rolling, kneading, rubbing, admixed will. The accelerator or antioxidant can be dry or in the form a filter cake or a flowable suspension. The electrolyte content should be kept as low as possible, otherwise the mixing of the polybutene with the active material is difficult and some of the polybutene tends to adhere to the To remove the vessel walls.

There are various processes for the production of agglomerates, z. B. extrusion, flake formation on drum dryers or low-pressure deformation.

The pressed material can then be dried in any way and the dried Product, if desired, can be sieved to remove any small amounts remove powdery residues. The waste powder can be reused.

The determination of the so-called dust index offers an excellent one Means for evaluating the dust generation of accelerators or anti-aging agents or mixtures containing accelerators and / or anti-aging agents.

An apparatus suitable for determining this index consists of one vertical, 86 cm long glass tube with a diameter open at the top of 5 cm, the lower end of which narrows in a V-shape and with a U-shaped tube of 7 mm in diameter is fused. 18 cm away from this fusion point the thicker tube has a slot that is so large that the slide of a Microscope can be inserted horizontally.

The U-shaped tube is connected to a compressed air line which is under a pressure of 0.21 kg / cm2. A 1 g sample is placed in the V-shaped part brought to the tube. A cloth held by a rubber band is placed over the top Place the end of the tube and the slot for the slide to prevent material loss covered during measurement. By introducing compressed air into the the U-shaped tube is blown up the sample into the 50 mm wide section of the tube. The air supply is then turned off and a microscope slide 15 seconds later inserted into the slot and left for 60 seconds. The ones on the slide the number of dust particles per square millimeter is determined microscopically.

The value found represents the dust index.

Table 1 gives the dust indices determined in the above method different accelerators. The designation 50 / o PB 1100-p denotes e.g. B. a powder mix that mixes with a commercial grade accelerator an amount of polybutene of 5 percent by weight of the accelerator, the Polybutene had an average molecular weight of 1,100; the designation 50 / o PB 1100-s denotes an identical mixture in extruded form. The designation 20 / o MO denotes a powder that contains an accelerator mixed with 20 / o mineral oil contains.

Table 1 Dust- index Dithiocarbamates Zinc dimethyldithiocarbamate ........... # 200 Zinc dimethyldithiocarbamate + 5% PB 1100-s ................... 5 Zinc diethyl dithiocarbamate ............ 50 Zinc diethyl dithiocarbamate + 5% PB 1100-s ................... 7 Zinc dibutyl dithiocarbamate ............ 360 Zinc dibutyl dithiocarbamate + 5% PB 1100-s ................... 10 Seleniethyldithiocarbamate ............. 35 Selenium diethyl dithiocarbamate + 5% PB 1100-s ................... 1 2-Benzthiazyl diethyldithiocarbamate ..... 10 2-Benzthiayzldiethyldithiocarbamat ..... + 5% PB 1100-s ................... 1 Dust- index Thiuram sulfides Tetramethylthiuram disulfide ............. <1000 Tetramethylthiuram disulfide + 2% MO 90 Tetramethylthiuram disulfide + 4% PB 1100-p .................. 27 Tetramethylthiuram disulfide + 4% PB 1500-p .................. 28 Tetramethylthiuram disulfide + 4% PB 3000-p .................. 50 Tetramethylthiuram disulfide + 5% PB 1100-s .................. 3 Tetramethylthiuram monosulfide ......... 16 Tetramethylthiuram monosulfide + 5% PB 1100-s .................. 0 Guanidines Diphenylguanidine ..................... 157 Diphenylguanidine + 5% PB 1100-s ..... 1 Thiazoles and thiazolines 2-mercaptobenzothiazole ............... 630 2-mercaptobenzothiazole + 5% PB 1100-s 6 2,2-benzthiazyl disulfide '................ <1000 2,2'-Benzthiazyl disulfide + 5% PB 1100-s 31 Benzthiazyl sulfide (zinc salt) ............ 264 Benzthiazyl sulfide (zinc salt) + 5% PB 1100-s ................... 4 2-Benzthiazyl-N-monocyclohexylsulfen- amid ............................. 86 2-Benzthiazyl-N-monocyclohexylsulfen- amid + 5% PB 1100-s .............. 4 2-mercaptothiazoline .................. 31 2-mercaptothiazoline + 5% PB 1100-s ... 0 The dispersibility of an accelerator manifests itself in its rolling properties and the quality of the vulcanizate formed.

The rolling properties of accelerator-polybutene mixtures and the respective untreated accelerators were compared using a butadiene-styrene copolymer containing 50 parts of easily processable carbon black contained per 100 parts of copolymer.

The accelerator mixture was processed as follows: 200 g of a synthetic rubber-carbon black base mixture were placed on 15 cm rollers Processed in diameter and 30 cm in length, with the distance between the guides was set to 150 mm and the distances between the rollers to 1.5 mm are. Cold water was passed through the rollers. 50 g accelerator were the added moving rubber mixture. Those for dissolving or dispersing the total amount of accelerator in the rubber compound was determined. Different accelerators were incorporated in this way in separate trials. The observations made in these experiments are summarized in Table 2.

The table also gives the approximate average sizes of the smallest Particles of some accelerators prior to incorporation into the accelerator mixture at. These values were determined by microscopic examination. In case of Extruded products, it was necessary to merate before the examination to break into their individual components by applying slight pressure.

Table 2 By- incision familiarization Particle Time size (Se- (Micron) customers) Dithiocarbamates Zinc dimethyldithiocarbamate .... | 2.2 | 115 Zinc dimethyldithiocarbamate + 50 / o PB 1100-s .......... 0.9 80 Zinc diethyl dithiocarbamate ..... | 2.4 | 100 Zinc diethyl dithiocarbamate + 50 / o PB 1100-s .......... 0.4 75 Zinc dibutyl dithiocarbamate ..... | 4.0 | 125 Zinc dibutyl dithiocarbamate + 50/0 PB 1100-s .......... 2.9 80 Selenium diethyl dithiocarbamate .... | 3.5 | 175 Selenium diethyl dithiocarbamate + 50 / o PB 1100-s .......... 3.0 85 2-benzthiazyl diethyldithio- carbamate + 50 / o PB 1100-s0 .. 3.0 120 2-Benzthiazyldiätn yldithio- carbamate .................. | 3.0 | 140 Thiuram sulfides Tetramethylthiuram disulfide - 310 Tetramethylthiuram disulfide + 20 / o MO ............... 2.4 220 Tetramethylthiuram disulfide + 40 / 0PB 1100-p ......... - 195 Tetramethylthiuram disulfide + 40 / o PB 1500-p ......... - 145 Tetramethylthiuram disulfide + 40 / o PB 3000-p ......... - 145 Tetramethylthiuram disulfide + 5% PB 1100-p .......... | - | 132 Tetramethylthiuramide sulfide + 5% PB 1100-s ........... | 1.5 | 85 Tetramethylthiuram monosulfide 8.0 165 Tetramethylthiuram monosulfide + 50 / o PB 1100-s .......... 7.5 110 Tetraethylthiuram disulfide ...... | 18.0 | 180 Tetraethylthiuram disulfide + 50 / o PB 1100-s .......... 15.0 95 Thiazoles and thiazolines 2-mercaptobenzothiazole ........ | 3.2 | 125 2-mercaptobenzothiazole + 50 / o PB 1100-s .......... 3.2 120 2,2'-Benzthiazyl disulfide ........ | 3.0 | 145 2,2'-benzthiazyl disulfide + 50 / o PB 1100-s .......... 3.0 100 Benzthiazyl sulfide (zinc salt) .... | 1.5 | 150 Benzthiazyl sulfide (zinc salt) + 50 / o PB 1100-s .......... 1.5 130 2-benzthiazyl-N-monocyclo- hexylsulfenamide ............ | 3.4 | 135 2-benzthiazyl-N-monocyclo- hexylsulfenamide + 50 / o PB 1100-s 3.6 105 2-mercaptothiazoline ........... | 66 | 160 2-mercaptothiazoline + 50 / o PB 1100-s .............. 71 90 The information in Table 2 proves that in all cases the incorporation, ie dispersion of the accelerator in a rubber mixture is extraordinarily accelerated by polybutene.

The procedure described here provides pre-rotations with high Accelerator concentrations.

These mixtures can be used with advantage as accelerator base mixtures be used.

The mixtures according to the invention can also be used directly as constituents of the mixture can be used in the manufacture of the vulcanizable rubber compounds. the The experiments described below illustrate the value of the experiments according to the invention Mixtures when used in such rubber compositions. In all cases the accelerator-polybutene admixtures could be incorporated into the mass much more quickly incorporate as the corresponding untreated accelerator. The quality of the The vulcanizate obtained was not affected by this. The use of the untreated Accelerator also caused harmful dust generation during the Mixing.

A basic mix of the following compositions was prepared: Smoked sheets .................... 100 Peptizers .................. 1 Antioxidants ................ 1 Stearic acid ......................... 1 Light processing oil ............ 2 zinc oxide .......................... 10 chalk, ground ................... 52 Soft clay ....................... 30 Easier to work with Sewer black 4 tetramethylthiuram disulfide + 50 / o PB 1100-s ................ 2 203 Zur The base mix was treated both untreated and treated in admixture with polybutene Accelerator used.

A vulcanizate was prepared by adding 203 g of the rubber base mixture were rolled with 4 g of untreated zinc dimethyldithiocarbamate, the same Conditions as noted above were used, and a second vulcanizate was also prepared from 203 g of the basic mixture mentioned and 4 g of zinc dimethyldithiocarbamate PB 1100-s.

Table 3 Vu! Kani- sation time module tensile strength extensible at 1600 C 300 O / o hardness (Minutes) (kg / cm2) (kglem2) (ovo) Vulcanized with untreated zinc dimethyldithio carbamate 3 330 1480 540 38 5 400 1420 520 39 10 400 1470 510 40 15 460 1330 490 40 Vulcanized with zinc dimethyldithiocarbamate + PB 1100-s 3 450 1460 540 37 5 500 1520 520 38 10 530 1500 510 40 15 500 1550 510 40 Using the same rubber rollers and the same production method, a vulcanizate with the following composition was produced: butadiene-styrene-rubber-carbon black premix ........... 150 parts zinc oxide ......... 5 parts Plasticizer ................. 5 parts sulfur ..................... 2 parts zinc dimethyldithiocarbamate ... 0, 4 parts Table 4 Volcanic Modulus stretchable- sation time tensile strength 300% hardness at 153 ° C (Minutes) (kg / cm²) (kg / cm²) (%) Vulcanizate with untreated zinc dimethyldithiocarbamate - - - - 5 490 1820 710 55 10 990 2730 600 60 15 1290 2920 530 59 30 1510 2890 480 58 Vulcanized with zinc dimethyldithiocarbamate + PB 1100-s 5 470 1710 680 55 10 1010 2870 620 60 15 1330 3120 550 60 30 1410 3190 520 60 In the following examples, the letters PB denote commercial polybutene and the number immediately following the letters denote the average molecular weight of this polybutylene.

Example 1 22 g of PB 1100 became 528 g of tetramethylthiuramide sulfide in a 41 capacity mixing vessel (kneader), which was provided with Sigma blades, added.

The mixture was kneaded for 30 minutes at ordinary temperature.

The product removed from the mixer was a white, non-dusting, free flowing powder.

Example 2 An aqueous suspension of 242 kg of zinc dimethyldithiocarbamate was mixed well with 6.45 PB 1100.

The mass was pressed out in a filter press and from it by means of an extrusion press made about 10 mm long prisms. These resulted after Drying and sieving a mechanically strong and non-dusting product.

Claims (1)

Claim: Process for the production of solid, non-dusting Mixtures of vulcanization accelerators and / or solid antioxidants in the form of powders or smaller agglomerates for rubber processing, whereby the mixtures contain liquid polybutene as a dust-binding agent, d a d u r c h g e k e n n -z e i c h n e t that one is liquid polybutene and / or liquid hydrogenated polybutene with molecular weights from 500 to 5000, preferably 750 to 3000, used in an anhydrous state. Considered publications: German Patent Specifications No. 879 305, 879 310; French Patent Nos. 999 693, 1,030,529; British U.S. Patent No. 689,249; Chemisches Zentralblatt, 1931, II, p. 2670.