FR2600070A1 - Process for the manufacture of crosslinkable halogenated hydrocarbon polymerisates, in particular of polyvinyl chloride and of its mixed polymerisates - Google Patents

Abstract

a. Process for the manufacture of crosslinkable halogenated hydrocarbon polymerisates, in particular of polyvinyl chloride and of its mixed polymerisates. …<??>b. Process characterised in that a silane containing a mercapto group, of general formula: … … is grafted onto a halogenated hydrocarbon polymerisate at a temperature of 60 to 220 DEG C, for 1 to 60 minutes, in a proportion of 0.5 to 10 parts by weight, calculated per 100 parts by weight of the polymerisate, in the presence of compounds containing lead or elements of the fourth group of the Periodic System, advantageously mono- to tribasic salts of organic or inorganic acids, advantageously tribasic lead sulphates.

Description

"Process for the manufacture of polymerization of halogenated hydrocarbons

crosslinkable, in particular with polyvinyl chloride. and its mixed polymerizates "The invention relates to a process for the production of polymerizates of halogenated, crosslinkable hydrocarbons, in particular of polyvinyl chloride.

and its mixed polymerizates.

In the manufacture by the known processes of crosslinkable halogenated hydrocarbon polymerizates, in particular of polyvinyl chloride, hydrazine and its derivatives, polyfunctional amino functional organic compounds, organic peroxides, for example dibenzoyl peroxide, are used. , among inorganic compounds, then metal oxides, for example oxides of magnesium, cadmium, lead (II), strontium, and the like. The crosslinking of these compounds occurs because they pick up on the polyvinyl chloride chain, a chlorine atom which binds to them. By recombination of radicals, a cross-linkage occurs between the chains. The crosslinking is carried out simply by heating at an elevated temperature, for example at 180 ° C., in a suitable mold, for a relatively long time, for example for 20 to 30 minutes. Due to the heating required for plasticization or, in the case of plasticized polyvinyl chloride, for gelation, the molding and crosslinking operation constitutes a loss of.

time consuming and uneconomical.

In other known crosslinking processes, unsaturated alkoxysilanes are used, for example vinyl triethoxysilane, which must first be grafted onto chlorinated polyethylene, and then, finally, is crosslinked, either alone or in admixture with chlorinated polyethylene. polyvinyl chloride, by hydrolysis of alkoxy groups by allowing hot water to act. The unsaturated alkoxysilane groups cannot be grafted onto pure polyvinyl chloride, but only onto chlorinated polyethylene which forms, with the polyvinyl chloride, a mechanical mixture, with a final low content of

gel, from 30 to 35%.

Further, a process is known for the crosslinking of a similar mixture, whereby chlorinated polyethylene is grafted with mercaptoalkylalkoxysilanes, in the presence of other ammonium compounds, for example tri-chloride. -propylammonium, which lower the grafting temperature to 100 ° C., so that during this operation, no polymer decomposition takes place. Among the hydrolyzable silanes, use is also made of aminoalkylalkoxysilanes, for example y-aminopropyltrimethoxysilane which grafts onto polyvinyl chloride, over a period of five minutes at a temperature of 160 ° C. After crosslinking in hot water o l ' dibutyltin dilaurate was emulsified as a catalyst to accelerate the reaction, a crosslinked polyvinyl chloride was obtained with a gel content of 79%, which content was determined by extraction in tetrahydrofuran. Aminoalkylalkoxysilanes grafted onto polyvinyl chloride form, without support, after crosslinking a structure with a high gel content, but by grafting they greatly reduce the heat stability necessary for subsequent processing, for example for extrusion. electrical tubular insulating tubes, or for extrusion

of cables.

All these known processes are either subject to significant technological requirements, or do not give the high gel content which would ensure a high resistance of the product to heat. The mentioned drawbacks are eliminated by the process for the manufacture of crosslinkable halogenated hydrocarbon polymers of the invention. The principle of the invention resides in that a silane containing a mercapto group is grafted onto a halogenated hydrocarbon polymerizate, of general formula: HS R1 - ii R2 / 3 - n / which means that: R1 is a group -CH2-, -C2H4-, -C3H6- to -C8H16 R2 a group -CH3-, -CH = CH2-, -C2H5 to -C5H11 Y a hydrolyzable group -OCH3, -C2H5, n or the graft is carried out at the plasticized state, at a temperature of 60 to 220 C, in 1 to 60 minutes, with a proportion of 0.5 to 10 parts by weight per parts by weight of polymer. The transplant takes place according to the equation:

+ 180_C_ C-H-

[-CH-CH2 -] + HS / CH2 / 35i / CH3 / 3 [-CH-CH2-In + HC C1 n to heat S / CH2 / 3Si / OCH3 / 3 So that the reaction is- i.e. substitution of the chlorine atom by mercaptosilane occurs, it is necessary that compounds be added which contain lead, or elements of the fourth group of the periodic system of elements, preferably organic salts dibasic or tribasic of organic acids, as well as minerals, particularly tribasic lead sulfate. Similarly, it has also been necessary to choose plasticizers, lubricants and substances which increase the efficiency of grafting and which prevent elimination reactions, which lead to deterioration of heat resistance. For this reason, according to another characteristic of the invention, plasticizers of the ester or amide type are used in the preparation of the mixtures, advantageously dioctyl phthalates, dioctyl adipate or tricresyl phosphate. In addition, to improve the processing properties, lubricants of the type of higher organic acids, their esters and their amides are used in an amount of 0.5 to 6 parts by weight. It is also possible to increase the efficiency of the grafting with the mercaptosilanes by addition of aminoalkylalkoxysilanes, advantageously of yaminopropyltrimethoxysilane, or of organic amines, advantageously of substituted tertiary amines and diamines, advantageously of tributylamine, hexamethylenediamine or C-naphthylamines. , in a proportion of 0.1 to 3 parts by weight. Finally, to increase the action of grafting, it is possible to add metal oxides, such as, for example, the oxides of cadmium, lead (II), vanadium- (V), zinc, calcium, of

strontium, or aluminum, in an amount of 0.1 to 3 parts by weight.

The fundamental advantage of the manufacturing process according to the invention lies in that the hydrolyzable alkoxy groups, linked via the silane to the polyvinyl chloride chaihe, as the source of the crosslinks, are relatively stable, in particular with exclusion. air humidity in closed packaging. In this way, it becomes possible to store, transport, and process them into desired products, as required by the organization of production. The crosslinking takes place slowly when the products are exposed to humidity in the air, or it can be accelerated with hot water or steam according to the following scheme:

S S S

RO-si-OR HO-Si-OH HO-Si-OH

OR OH

H20 cat.

> R> O

O - ROH - H20

OR OH

RO-Si-OR HO-Si-OH HO-Si-OH

S S S

In the process carried out industrially heretofore for the manufacture of polyvinylchloride crosslinkable by causing hydrazine or its derivatives to act, it is necessary to heat the corresponding mixture in a mold for a sufficient time so that the

Crosslinking occurs, as rubber mixes are vulcanized. This process wastes time and is very thirsty for thermal energy.

The mercaptoilane graft is not only suitable for use on hard polyvinyl chloride having a low lubricant and plasticizer content, but also on plasticized mixtures with a high plasticizer content, which are used for the production of sheets. , cables, floor coverings, or in the case of polyvinyl chloride pastes for

manufacture of artificial leather.

The grafting with the mercaptosilanes is carried out with complete mixtures, by heating at a temperature of 150 to 180 ° C. for three to six minutes.

For the grafting, a standard installation is used, that is to say, a single or double screw crushing machine, an extruder, or a heated crushing machine. If the operation is carried out on a paste of polyvinyl chloride applied to a textile or other support, the high temperature grafting does not last longer than is necessary for the gelation of the application. The mixture which has undergone a graft in this way does not contain any gel, that is to say no crosslinked structure, the presence of which could result in processing difficulties during forming. After the grafting, a determination is made of the gel content which should not be greater than 3%. The crosslinking of the graft mixture occurs in the second phase, by hydrolysis of the alkoxy groups, either spontaneously, by a long-lasting action of air humidity, or in hot water, or in steam at 60 at 100 C for 2 to 6 hours, depending on the thickness of the product. To accelerate this hydrolysis, dibutyltin dilaurate as a catalyst is added to the mixture, before grafting, in an amount of 0.05% by weight, or this catalyst is mixed with the hot water used, in the proportion of 3 to 5% by weight. The crosslinking is pushed to the maximum gel content, that is to say 20 in proportion by weight of insoluble after extraction with

tetrahydrofuran.

-The graft takes place at high temperatures at the same time as the operation of homogenization of the mixtures, their plasticization or their gelling. cation, so that the energy required for the manufacture of crosslinkable polyvinyl chloride is approximately equal to that required for the

manufacture of non-crosslinkable products.

The grafted, crosslinkable polyvinyl chloride has good heat resistance, as long as it is not subjected to hydrolysis, can be transformed by all technologies of injection, extrusion, calendering, and any waste can be reused. The accelerated, hydrolytic crosslinking of the products, by exposure to increased humidity with hot water or steam, represents an ancillary technological operation, which can be

carried out in an installation which does not require any significant investment.

The process according to the invention is explained in more detail below with reference to a few examples.

of achievement.

Example 1:

A mixture of which the composition in parts by weight is as follows: Polyvinyl chloride suspension 100 Dioctyl phthalate 45 Chalk 20 Tribasic lead sulphate 5 γ-mercaptopropyltrimethoxysilane 5 sodium dilaurate is triturated for 10 minutes in a so-called "plastograph" apparatus. dibutyltin 0.05 From this mixture, a plate with a thickness of 1 mm is pressed and subjected to steam for 6 hours at a temperature of 100 C. The gel content before this vaporization amounts to 1 %, and after crosslinking, 65%. A sample piece, in the form of a ribbon is deposited for 15 minutes in a dryer at a temperature of 150 ° C. and is subjected to a tension of 2 N / mm. The strain stabilized with an extension of 25%, while an uncrosslinked comparative sample of the same composition settled down.

torn after being heated for 1 minute.

Example 2:

A mixture having the same composition as that of Example 1, but where the mercaptosilane was used in the proportion of 3.4 parts by weight, was triturated in a "plastograph" at different temperatures and was carried out. obtained on the pressed specimens, the following results: Grafting for 10 min at a temperature of

1800C 190 C 200 C

Gel content before vaporization (%) Gel content after crosslinking (%)

Example 3:

0o Mixtures with different plasticizer contents are prepared having the following composition in parts by weight Polyvinyl chloride suspension 100 Heat stabilizer 5 ymercaptopropyltriethoxysilane 3,6 dibutyltin dilaurate 0,05 dioctyl phthalate 5; 9; 20 and 45 The grafting was carried out in 10 minutes at 180 ° C. and the crosslinking in six hours, in boiling water. The following values were found for the gel contents Dioctyl phthalate contents (part by weight)

9

Gel content before vaporization (%) gel content after crosslinking ('%) Gel content after calculation on PVC (%) Example 4:

1.5 0.5

0.3 0.2

87 84

81- 83

A PVC (polyvinyl chloride) paste was prepared having the following composition in parts by weight Polyvinyl chloride emulsion paste forming 100 dioctyl phthalate 70 heat stabilizing 3 γ-mercaptopropyltriethoxysilane 6 dibutyltin dilaurate 0.05 The paste was applied to a substrate with a thickness of 1 mm and the gelation was carried out for 20 minutes at 180 C. The determination revealed a gel content before vaporization of 3%,

after 48.5% crosslinking, after calculation based on 84% pure PVC.

Example 5:

By plasticizing for 10 minutes at 180 C, a hard PVC mixture was prepared having the following composition in parts by weight Polyvinyl chloride suspension 100 Heat stabilizer 5 Lubricant 3 mmercaptopentyltriethoxysilane 6 dibutyltin dilaurate 0.05 t gel content before vaporization at 1%,

after vaporization, in the crosslinked state, at 91%.

Example 6:

A mixture is prepared having the same composition as in Example 1, with the difference -25 that, for the grafting, a combination of mercaptosilane and aminosilane is used with the following dosage ymercaptopropyltrimethoxysilane 1.6 part. by weight yaminopropyltrimethoxysilane 0.8 parts. by weight The mixture is triturated for 10 min at 180 ° C. and a gel content of 2% is observed before vaporization, and of 55% after crosslinking. The aminosilane caused a lowering of the mercaptosilane concentration, although the same gel content was obtained after crosslinking. Tertiary amines have offered a similar effect, for example tributylamine, with which, with a dosage of 1 to 3.5 parts by weight of mercaptosilane, a gel content of 66% after crosslinking has been obtained.

R E V E N D I CATI ONS

1) Process for the manufacture of crosslinkable halogenated hydrocarbon polymerisates, in particular of polyvinyl chloride and its mixed copolymers, characterized in that a silane containing a mercapto group is grafted onto a halogenated hydrocarbon polymerizate, of general formula:

HS - R1 - - R2

no R1 is a group -CH2-, -C2H4-, -C3H6- to -c8H16 15 R2 R2 a group CH3-, -CH = CH2-, -C2H5- to -CsHl Y a hydrolyzable group -OCH3, -C2H5, n 0 or 1 at a temperature of 60 to 220 C, for 1 to 60 minutes, in a proportion of 0.5 to 10 parts by weight calculated on 100 parts by weight of the polymerizate, in the presence of compounds containing lead or elements from the fourth group of the periodic system, advantageously mono to tribasic salts of organic or inorganic acids,

advantageously tribasic lead sulphate.

2) Process according to claim 1, characterized in that plasticizers and lubricants of the ester or amide type, advantageously di-2-ethylhexyl phthalate, dioctyl adipate or tricresylephosphate, are used.

3) Method according to one of the claims

1 and 2, characterized in that one adds aminoalkoxysilane, advantageously Y-aminopropyltrimethoxysilane, or organic amines, advantageously ter-

substituted tials, diamines and ammonium salts, advantageously tributylamine, hexamethylenediamine, or: -naphthylamine, in a proportion of 0.05 to 3 parts

in weight.

4) Process according to any one of the

claims 1 to 3, characterized in that one adds

metal oxides such as oxides of cadmium, vanadium (V), lead (II), zinc, calcium, strontium, and

aluminum, in an amount of 0.1 to 3 parts by weight.

VS