DE1269350B - Process for the production of free-flowing vinyl chloride polymers suitable for hard processing by suspension polymerization - Google Patents

Description

Process for the production of free-flowing, for hard processing suitable vinyl chloride polymers by suspension polymerisation suspension polymers of vinyl compounds and their copolymers are known with the aid of protective colloids or combinations of protective colloid and ionic wetting agent or also of ionic wetting agent and metal salt as a dispersing system in the presence of organic, monomer-soluble catalysts produced.

Especially for hard processing, e.g. B. on extruder machines, obtained practically unsuitable products with rough and porous surfaces. Conditional Due to this unsuitable grain structure of the product, its absorption capacity in the screw is impaired, so that the throughput inevitably drops. So is at the processing into injection molded articles the shape of the mass is not filled, what leads to a large amount of rejects.

It has been found that they can be poured for hard processing suitable vinyl chloride polymers by suspension polymerisation using of gelatin in amounts of 0.06 to 0.15 percent by weight as protective colloid, organic, monomer-soluble peroxides in amounts of 0.1 to 0.3 percent by weight as catalysts as well as stabilizers can be produced in a simple manner if one works as a stabilizer 2,6-di-tert-butyl-4-methylphenol in amounts from 0.005 to 0.1 percent by weight, all Information based on the vinyl chloride used.

The gelatin used is preferably alkali-hydrolyzed powder gelatin in question. This gelatin differs from the usual commercial gelatins both by the freezing point, the viscosity and the conductivity as well as by the type of raw materials used and their treatment during the 2 to 3 months permanent fermentation. Also the ash content and the purity of the usual gelatins do not correspond to this type of gelatin, which should rather be viewed as photo gelatin.

Usable peroxide catalysts are, for. B. lauroyl peroxide, sulfonyl peroxide, Benzoyl peroxide, isopropyl percarbonate and their mixtures. Azo catalysts are not suitable because they release nitrogen under the processing conditions and thus lead to the formation of bubbles in the end product.

A particular advantage of this method is that all Additions to the aqueous phase can be added before the vinyl chloride is added, after which it is polymerized as usual. The addition of 2,6-di-tert-butyl-4-methylphenol takes place preferably before the polymerization, whereby compared with the same amount added a later addition during the polymerization a better effect is achieved. The polymerization itself can be carried out in the usual way.

According to the method according to the invention for hard processing perfectly suitable crystal clear polymers with an average grain size of 155, u i 1401o with a simultaneous bulk weight of 650 gil ifr 7.2 01o (Determination method: DIN 53 468) obtained reproducibly. Leave these polymers in high throughputs of 500 to 550 g / min z. B. on extruders to colorless Process moldings. In view of the previously used for heat stabilization Stabilizers such as B. Lead stabilizers, which usually promote polymerization inhibit and contaminate the polymerization plants, it was surprising that according to the previously observed disadvantages of the method according to the invention in so much can easily be avoided. In addition, the after Processes obtained polymers despite the stabilizer content by physiological Harmlessness.

The technical progress that can be achieved with the process is illustrated illustrated in the examples below.

Example 1 In one equipped with an impeller stirrer and baffle 170 parts by weight of deionized water are placed in a pressure autoclave, 0.1 parts by weight alkali-hydrolyzed powder gelatin added and 1 hour touched. Then 0.24 part by weight of lauroyl peroxide and 0.01 part by weight of 236-di-tert-butyl-4-methylphenol are added added and, after evacuating the autoclave, introduced 100 parts by weight of vinyl chloride.

The polymerization temperature is at a pressure of 9.2 atm and a stirrer speed of 120 rpm (corresponding to a peripheral speed of 5.1 m / sec) 61 "C. After a running time of about 11l / 2 hours the pressure drops 4 atü from. After releasing the pressure in the autoclave, the suspension is z. B. over a centrifuge and dryer, worked up. The yield is about 93010 Polyvinyl chloride.

Table I summarizes the results of experiments in a 150-liter polymerization kettle, according to which the optimum amounts of gelatin and the optimum type of gelatin can be clearly determined. Thereafter, up to 0.05,010 gelatine, based on vinyl chloride, the grain spectrum is shifted too far to the coarse side. To achieve the most favorable polymer properties for hard processing, namely both a grain size of 155 μ ~ 14% and a bulk density of 650 g / li 7.2%, the optimal amount added is between 0.06 and 0.15%. With additions above 0.15% the bulk density drops, whereby the grain spectrum does not become more uniform (cf. the gradient factor that characterizes this!). The gradient factor indicates the tangent in the RRS diagram, the so-called uniformity number (»RRS diagram« = Rosin-Rammler diagram, a logarithic table Bulk Ver suspension means sieve analysis look for weight No. Type (%) (g / l) 0 to 60 100 150 200 1 alkali-hydrolyzed powder gelatin 0.05 583 3.2 0.5 2.8 0.5 11.0 2 same 0.075 612 2.1 3.9 22.4 39.0 17.5 3 same 0.10 635 3.6 5.9 40.7 40.7 5.0 4 the same 0.15 681 6.6 16.6 23.2 39.3 11.8 5 same 0.20 651 12.4 34.5 46.9 4.7 4.7 6 same 0.30 677 13.3 23.7 42.2 14.2 5.7 7 same 0.40 510 8.8 28.3 44.3 12.9 4.1 Table II Bulk Ver suspension means sieve analysis look for weight No. Type (%) (g / l) 0 to 60 60 100 150 200 8 Alkali hydrolyzed powder gelatin 0.1 635 3.6 5.9 40.7 40.7 5.0 9 also 0.30 677 13.3 23.7 42.2 14.2 5.7 10 * 0.10 542 0.3 4.6 21.1 15.8 3.7 11 * 0.30 477 8.5 13.6 36.5 35.6 5.9 12 ** 0.10 444 21.2 18.5 6.7 1.2 1.2 13 ** 0.30 452 25.0 19.0 4.9 0.5 1.1 Experiments 1, 5, 6, 7, 9, 10 to 13 are comparative experiments.

* Polyvinyl alcohol with a viscosity of a 4% aqueous solution at 20 ° C of 25cP and a saponification number mg KOH per gram of 240.

** Methyl cellulose with a viscosity of a 2% aqueous solution at 20 ° C from 65 cP.

Table III Polymerization fully demineralised Experiment kettle size water vinyl chloride catalyst (m3) (kg) (kg) (a) 6,3,600 1,800 lauroyl peroxide, 0.25%, based on monomer (b) 6,3,600 1,800 lauroyl peroxide, 0.25% based on monomer mixed diagram of the particle sieve analysis; Literature see E. R amm 1 er, VDI-Beihefte, process engineering, 1937, pp. 161 to 168). The throughput, e.g. B. in the extruder, is represented by the product of bulk density and average grain, divided by 1000, it reaches its maximum in the specified optimal additional range.

A use of gelatin through other suspending agents, such as polyvinyl alcohol with a viscosity of a 4% strength aqueous solution at 20 ° C. of 25 cP and a saponification number mg KOH per gram of 240 or methyl cellulose with a viscosity of 2% aqueous solution at 200 C of 65 cP, results, as can be seen from the table, in addition to one completely different grain properties a fluctuating mean partial chen size, a lower bulk density and, associated with this, a considerably lower one Throughput in the extruder. Only if the specified conditions are strictly observed thus achieved the desired optimal result.

Example 2 Vinyl chloride was according to the information in Table III once in a comparative experiment a) without and on the other hand in experiment b) with 2,6-di-tert-butyl-4-methylphenol polymerized as a stabilizer.

Experiment b) leads, compared to experiment a), to a product with increased flowability (see table) and increased thermal stability. Sieve analysis Gradient Average Kx d *** Throughput Grain 250 300 400 500 750 1000 factor com (g / min) form **** 6.9 8.3 4.6 10.1 8.3 44.0 1.16 1,000 - 1 12.4 2.7 track 3.29 190 116 1 3.2 0.9 lane 3.42 170 108.0 1 2.2 0.5 2.74 170 116 1 0.78 0.4 0.4 2.27 120 78 1 1.0 lane 2.45 130 88 1 0.9 0.6 2.50 130 66.3 1 Seib analysis Gradient Average Kx ds *** Throughput grain 250 300 400 500 750 1000 grain factor (g / min) shape **** 3.2 0.9 trace 3.42 170 108 530 1 1.0 lane 2.45 130 88 530 1 0.9 0.9 0.6 1.2 1.2 49.6 1.77 1000 - 485 2 Lane 2.93 155 74 381 2 0.6 1.8 0.4 7.3 3.6 35.5 0.52 850 377 286 2 1.1 4.9 6.5 17.9 8.7 10.3 0.74 480 217 389 2 *** Product of bulk weight and average grain by 1000.

**** Grain shape 1 = transparent, crystal clear ball, not porous, not capillary active, ideally suited for hard processing.

Grain shape 2 = agglomerate, opaque, irregularly porous surface, capillary active, poorly suited for hard processing. 2,6-di-tert-butyl pourability Alkali hydrolysed phosphorus-4-methylphenol bulk density funnel width Gelating acid (85%)% based on 30 mm 40 mm (%) (cm3) on monomer (g / l) (g / s) 0.3 600 - 520 91 140 0.3 600 - 0.01 523 107 167

Claims (1)

Claim: Process for the production of pourable, for vinyl chloride polymers suitable for hard processing by suspension polymerization using gelatin in amounts of 0.06 to 0.15 percent by weight as protective colloid, organic, monomer-soluble peroxides in amounts of 0.1 to 0.3 percent by weight as catalysts so- like stabilizers, marked by the fact that one as a stabilizer 2,6-Ditert. -butyl-4-methylphenol in amounts of 0.005 to 0.1 percent by weight, all information is based on the vinyl chloride used. Documents considered: German Auslegeschrift No. 1 012072.