CS262332B1 - Process for preparing vulcanizable halogen-hydrocarbon polymers - Google Patents

Abstract

The crosslinkable polymers (I) are prepd. by reacting a halogen-hydrocarbon polymer (II) with 0.5-10 pts. wt. mercapto-terminated silane (III) of formula HS-R1-Si(Y)3-n-R2n per 100 pts. wt. (II) at 60-220 deg.C for 1-60 mins. in presence of cpd. (IV) contg. Pb or (sic) one or more elements of Gp. 4, where R1=CH2-, -C2H4-, -C3H6- to C8H11- gp.; R2=Me, vinyl, Et to pentyl; Y=hydrolysable -OMe or -Et (sic. OEt); n=0 or 1. (II) is PVC or VC copolymer. (IV) is mono- to tri-basic salt of an organic or inorganic acid, partic. tribasic Pb sulphate. Process is carried out in presence of ester or amide-type plasticiser or lubricant (inhibiting elimination reactions and increasing grafting), partic. di-2-ethylhexyl phthalate, dioctyl adipate, or tricresyl phosphate; or 0.05-3 pts. wt. of an aminoalkoxysilane, partic. 3-aminopropyl trimethoxysilane, or an organic amine, partic. substd. tert. amine or a diamine, or an ammonium salt, esp. Bu3N, hexamethylenediamine, or alpha-naphthylamine; or 0.1-3 pts. wt. metal oxide, partic. of Cd, V (v) Pb (ii), Zn, Ca, Sr or Al.

Description

The invention relates to a process for the production of crosslinkable halogenated hydrocarbon polymers, in particular polyvinyl chloride and copolymers thereof.

Hitherto known processes for the production of crosslinkable halocarbon polymers, especially polyvinyl chloride, use hydrazines and derivatives thereof, multifunctional organic amino compounds, organic peroxides such as dibenzoyl peroxide, and inorganic compounds metal oxides such as cadmium, magnesium, lead, strontium and others. Crosslinking with these compounds occurs by cleaving the chlorine atom from the polyvinyl chloride chain, which binds to each other. Cross-linking occurs between the chains by recombination of radicals. The crosslinking can only be carried out by heating to a higher temperature, for example 180 ° C, in the respective utility block for a relatively long time, for example 20 to 30 minutes. With the heating required for plasticization or, in the case of plasticized polyvinyl chloride for gelation, the shaping and crosslinking process is lengthy and uneconomical.

Other known cross-linking methods use unsaturated alkoxysilanes, for example vinyltriethoxysilane, which is first grafted to chlorinated polyethylene and crosslinked, either alone or in admixture with polyvinyl chloride, by hydrolysis of the alkoxy groups by treatment with hot water. Unsaturated groups of alkoxysilanes cannot be grafted onto pure polyvinyl chloride, but only to chlorinated polyethylene, which forms a mechanical mixture with polyvinyl chloride with a resulting low gel content of 30-35%.

It is further known to crosslink a similar composition wherein chlorinated polyethylene has been grafted with mercaptoalkylalkoxysilanes, for example gamma-camptopropyltriethoxysilane in the presence of other ammonium compounds, for example tri-n-propylammonium chloride, which lower the grafting temperature to 100 ° C to avoid grafting polymer degradation. Of the hydrolyzable silanes, aminoalkylalkoxysilanes, such as gamma-aminopropyltrimethoxysilane, are grafted to polyvinyl chloride for 5 minutes at 160 ° C. After crosslinking in hot water, in which dibutyltin dilaurate was emulsified as a catalyst to accelerate the hydrolysis, a cross-linked polyvinyl chloride was obtained with a gel content of 79%, determined by extraction in tetrahydrofuran. Aminoalkylalkoxysilanes grafted onto polyvinyl chloride provide, after crosslinking, a high gel structure, but greatly reduce the heat stability required for further processing such as extrusion of pipes, electrical insulating tubing or cable extrusion when grafting.

All of these known processes are either technologically demanding or do not provide a high gel content, guaranteeing a higher shape stability of the products when hot.

These drawbacks are overcome by the process for producing the crosslinkable halocarbon polymers of the invention. Its principle consists in that the halocarbon polymer is grafted silane containing mercaptan group of the formula HS-R ¹ -Si / or _^2/3 wherein R ¹ is an alkylene group with 3-5 carbon atoms

R is -CH ₃ -, or -C ₂ H ₅ , at 60 to 220 ° C for 1 to 60 minutes in an amount of 0.5 to 10 wt. parts per 100 wt. parts of the polymer in the presence of compounds containing lead or elements of the fourth group of the periodic system, suitably basic to tribasic salts of both organic and inorganic acids, suitably tribasic lead sulphate. According to a further aspect of the invention, plasticizers and lubricants of the ester or amide type, preferably di-2, ethylhexyl phthalate, dioctyladipate or tricresyl phosphate, are still present in the reaction mixture. It is further preferred to add aminoalkoxysilanes, suitably gamma-aminopropyltrimethoxysilane or organic amines, suitably substituted tertiary amines, diamines and ammonium salts, suitably tributylamine, hexamethylenediamine or alpha-naphthylamine in an amount of 0.05 to 3 wt. parts per * 100 wt. parts of the polymer. Finally, according to the last aspect of the invention, metal oxides such as cadmium, vanadium, lead, zinc, calcium, strontium and aluminum are added in an amount of 0.1 to 3 wt. parts per 100 wt. parts of polymer®

The main advantage of the process according to the invention is that the hydrolyzable alkoxy groups bonded via the silane to the polyvinyl chloride chain as a cross-linking source are relatively stable, especially in the absence of atmospheric moisture in the sealed package. The polymers produced can therefore be stored, transported and processed into the necessary products as required by the production organization. Sulfurization occurs slowly by exposing the products to atmospheric moisture or accelerating in hot water or steam. In the prior art process for the production of crosslinkable polyvinyl chloride by the action of hydrazines and their derivatives, it is necessary to heat the respective mixture in a block until crosslinking occurs similarly to the vulcanization of rubber mixtures. This process is lengthy and heat-intensive.

The grafting of mercaptosilanes can be carried out not only for hard polyvinyl chloride with a low content of lubricants and plasticizers, but also for softened compounds with a high content of plasticizers used for the production of foils, cables, flooring or in the case of polyvinyl chloride pastes in the manufacture of imitation leather.

The grafting of the mercaptosilanes is performed on complete mixtures by heating at 150 to 180 ° C for three to six minutes. For grafting, a standard device is used, i.e. a kneading or twin screw, an extruder or a heated kneader. In the case of polyvinyl chloride pastes applied to a textile or other substrate, the grafting process does not take a longer time at higher temperatures than is necessary for gelation of the deposits. Such grafted compositions do not contain a gel, i.e. a force structure, the presence of which would cause processing difficulties during shaping. After grafting, the gel is determined to be no more than 3%. The grafting of the grafted seals is carried out in the second phase by hydrolysis of the alkoxy groups either spontaneously with long-term air humidity or in hot water or steam of 60 to 100 ° C for 2 to 6 hours, depending on the thickness of the product. To accelerate this hydrolysis, dibutyltin dilaurate is added to the mixtures prior to grafting in an amount of 0.05 wt. % or this catalyst is added to the hot water in an amount of 3 to 5 wt. %. Cross-linking was carried out to the maximum gel content, i.e. the insoluble weight fraction after extraction with tetrahydrofuran.

The grafting takes place at elevated temperatures simultaneously with the process of homogenizing, plasticizing or gelatinizing the mixtures, so that the energy for the preparation of the crosslinkable polyvinyl chloride is almost identical to that of the non-promiscuous products.

The grafted crosslinkable polyvinyl chloride has good thermal stability until it undergoes hydrolysis, can be processed by all injection, extrusion and calendering technologies and any waste can be reprocessed. In addition, the technological operation is accelerated hydrolytic vibration of products by exposure to increased moisture in hot water or steam, which can be done on equipment that does not require large investments.

The process according to the invention is described in more detail below on several exemplary embodiments. The abbreviation dsp * denotes parts by weight based on 100 parts by weight of the starting polymer. He did

In a plastograph, a mixture of the following composition was kneaded for 10 min at 180 ° C:

suspension polyvinyl chloride 100 wt. parts dioctyl phthalate 45 dsp chalk 20 dsp tribasic lead sulphate 5 dsp gamma-mercaptopropyltrimethoxysilane 5 dsp * dibutyltin dilaurate 0.05 dsp

A 1 mm thick plate was pressed from the mixture and exposed to steam at 100 ° C for 6 h. The gel content before steaming was 1% and after crosslinking 65%. The tape-shaped test piece was placed for 15 min in an oven heated to 150 ° C and loaded at 20 MPa. The deformation stabilized at an elongation of 25% while the noncrosslinked comparative sample of the same composition ruptured within 1 minute after heating.

Example 2

A mixture of the same composition as Example 1 using 3.4 msp mercaptosilane was kneaded in a plastograph at various temperatures and the following results were obtained from the molded test pieces:

Gel content before steaming /% /

Gel content after cross-linking /% /

Example 3

Mixtures with various suspension polyvinyl chloride heat stabilizer gamma-mercaptopropyltriethoxy8 ilane dibutyltin dilaurate dioctyl phthalate were prepared

Grafting for 10 min at temperature

160 ° C 190 ° C 200 ° C

00

5758 plasticizer content:

100 wt. d.

dsp

3.6 dsp

0.05 dsp

5; 9} 20 and 45 dsp

The grafting was performed for 10 min at 180 ° C and sulfurized for 6 hours in boiling water. The following gel contents were measured;

Dioctyl phthalate content (dsp)

20 45

Gel content before steaming /% / Gel content after crosslinking /% /

Gel content after conversion to PVC /% /

1.5 0.5 0.3 0.2 78 70 65 54 87 84 81 83

Example 4

PVC paste was prepared with the following composition:

emulsion paste-forming polyvinyl chloride dioctyl phthalate thermal stabilizer gamma-mercaptopropyltriethoxysilane dibutyltin dilaurate

100 wt. d.

dsp dsp dsp

0.05 dsp

The paste was applied to a 1 mm thick substrate and gelatinized for 20 minutes at 180 ° C.

The gel content before steaming was determined to be 3%, after cross-linking 46.5%, after conversion to pure

PVC 84%.

Example 5

By plasticizing for 10 minutes at 180 ° C a mixture of hard PVC was prepared with the following composition:

suspension polyvinyl chloride heat stabilizer lubricant epsylon mercaptopentyltriethoxysilane dibutyltin dilaurate

100 wt. d.

dsp dsp dsp

0.05 dsp

The gel content before steaming was 1%, after steaming in the crosslinked state 91%,

Example 6

A composition as in Example 1 was prepared except for the composition of alkoxysilanes in grafting, where a combination of mercaptosilane and aminosilane was used with dosing with gamma-mercaptopropyltrimethoxysilane gamma-aminopropyltrimethoxysilane

1.6 dsp

0.8 dsp

The mixture was kneaded for 10 minutes at 180 ° C and the gel content was determined before steaming and after crosslinking 55%. A similar effect has tertiary amines, such as tributylamine, which at a dosage of 1 dsp to 3.4 dsp of mercaptosilane reached a gel content of 66% after crosslinking.

Claims (4)

SUBJECT OF THE INVENTION 1. A process for producing sířovatelných halohydrocarbon polymers, especially polyvinyl chloride and vinyl chloride, characterized in that the halocarbon polymer is grafted with a silane containing a mercaptan of the formula HS-R ¹ -Si / or _^2/3 wherein R ¹ is an alkylene group with 3-5 carbon atoms R is a group or ^C 2 ^H 5 'at a temperature of 60 to 220 ° C for 1 to 60 minutes in an amount of 0.5 to 10 wt. parts per 100 wt. parts of the starting polymer in the presence of lead containing compounds or elements of the fourth group of the periodic system, such as basic to tribasic salts of both organic and inorganic acids, suitably tribasic lead sulphate. 2. Process according to claim 1, characterized in that the grafting is carried out in the presence of an emollient and an ester or amide type lubricant, preferably di-2, ethylhexyl phthalate, dioctyladipate or tricresyl phosphate. 3. Process according to claim 1, characterized in that the grafting is carried out with the use of aminoalkoxysilanes, such as gamma-aminopropyltrimethoxysilane, or organic amines, such as substituted tertiary amines, diamines and ammonium salts, suitably tributylamine, hexamethylenediamine or alpha-naphthylamine. , 05 to 3 wt. parts per 100 wt. parts of the starting polymer. 4. The process according to claim 1, wherein the grafting is carried out in the presence of metal oxides such as cadmium, vanadium, lead, zinc, calcium, strontium and aluminum in an amount of 0.1 to 3 wt. parts per 100 wt. parts of the starting polymer.