DE2437093C2 - Process for preventing crosslinking of vinyl chloride-vinyltrialkoxysilane copolymers - Google Patents

Description

Polymers of vinyl chloride with vinyl trialkoxysilanes of the general formula

, OR
CH ₂ = CH-Si-OR

tend to crosslink during storage and often during polymerization. This is undesirable because it makes perfect processing difficult or impossible. In the thermoplastic processing interfere with small amounts of crosslinked components, z. B. 5%, little or no. In contrast, higher percentages are particularly disadvantageous in injection molding.

When processing on the dissolved state, e.g. B. via a spinning solution or a dissolved paint batch, even small amounts of cross-linked fractions interfere with the Processing sensitive. The filters are easily clogged and clogged when such solutions are spun disturb a continuous process very much. In the case of paints, there are uneven surfaces and processing, z. B. via a spray gun is sensitive to disruptions.

It has now been found that this night can be reported can, if you the copolymerization of vinyl chloride with Vlnyltrialkoxysilanen In the presence of 1,2-epoxides with the following structural unit

- C-

performs.

The invention is therefore a method for Prevention of networking in the under usual. Conditions carried out copolymerization of Vinyl chloride with vinyltrialkoxysilanes and, if appropriate, other ethylenically copolymerizable with vinyl chloride unsaturated monomers in the presence of free radical-forming catalysts and optionally customary additives, which is characterized in that the polymerization before or during the Copolymerization of 1,2-epoxides.

The epoxy structure can be present one or more times in the molecule of the corresponding compound be. Connections of this type are z. E.g .: 2,3-epoxybutane or octane, 1,2-epoxy-ethylene benzene, the bisglycidyl ether of 4,4'-dihydroxy-dlphenyl-dlmethylmethane, the glycidyl ester of acrylic acid, epoxidized Soybean oil.

The epoxy compounds are added to the polymerization batch as indicated above. Tries if the epoxy compounds are incorporated subsequently, crosslinking phenomena still occur, however, it is possible, especially in the case of copolymers in solutions, to add the epoxy compounds to the end Add copolymerization without crosslinking phenomena occurring during subsequent storage.

The crosslinking occurring during the known copolymerization can be influenced by the choice of auxiliaries. The crosslinking can be achieved by using percarbonates as initiators (DE-PS 20 46 118) or by Use of regulators (DE-PS 20 64 145) can be partially prevented, but occurs in any case when storing the Copolymers. Since the addition of the epoxides according to the invention reliably prevents the crosslinking, Peroxide initiators other than percarbonates can also be used for the copolymerization without cross-links occur during the copolymerization of vinyl chloride with vinyltrialkoxysilanes. By d ^ e So epoxy compounds are used both during the copolymerization of vinyl chloride with vinyltrialkoxysilanes as well as after the copolymerization during storage prevents crosslinking. On the other hand, they disturb Epoxy compounds desired subsequent crosslinking by adding certain compounds, e.g. B. Hypophosphorous acid, no. So can be prepared from the solution according to the present process Copolymers of vinylchlorld vinyl trialkoxylane, e.g. B. cross-linked lacquer coatings or fibers, without Schwlerlgkelten produce.

To the extent that the process of DE-PS 20 46 118 or 20 64 145 is used. Is the addition of epoxies also possible during the copolymerization of vinyl chloride with vinyltrialkoxysilanes. If the polymer

• »0 sation not according to the special procedure of this In both patents, the epoxides have to be added before the copolymerization, otherwise they are crosslinked Shares arise in the copolymer. This z. B. in the two-stage mass polymerization.

In this process, high-speed stirrers and rapidly disintegrating peroxides are used in the first stage. This includes B. the cyclohexanesulfonylacetyl peroxide. This peroxide gives but without the addition of epoxies. In the first phase of the copolymerization of vinyl chloride, for. B. with 5 wt .-% vinyltrialkoxysilanes, crosslinked components that interfere in the further copolymerization and in the processing of the copolymers.
Accordingly, in the context of the present process, the customary cataclysmic processes of copolymerization of vinyl chloride with vinyl chloride and optionally other ethylenically unsaturated monomers copolymerizable with vinyl chloride can be used. The proportion of the silanes in the copolymer can be 0.1 to 20 wt C atoms, is.
The amount of epoxy, without being limited to this information, will generally be 0.1 to 5% by weight based on vinyl chloride, but 0.2 to 2.5% by weight, in particular 0.5 to 1, should be used , 5 wt. 96 result as expediently preferred amounts.

It has been found that in the presence of the epoxies, copolymerization is possible even in the aqueous phase in which the water usually interferes by hydrolysis of the vinyltrialkoxysilanes. This can be very surprising also the procedures of vinyl chloride polymerization in aqueous suspension or dispersion on the copolymerization of vinyl chloride with vinyltrialkoxysilanes are transferred or, in the case of polymerization in the organic phase, the previously necessary or careful All reactants do not dry out.

Example I.

A 30-liter steel autoclave is flushed several times with nitrogen. 6175 g of vinyl chloride, 325 g of freshly distilled Vinyltrläthoxysllan, 65 g of epoxidized soybean oil and 19.5 g of dicetyl percarbonate are placed in the autoclave. The stirring takes place with a regular ribbon mixer. The autoclave is heated to 5O ⁰ C and the ribbon mixer at 100 rpm moved. The pressure is regulated to 7.8 bar via a relay. The attempt is terminated after 7 hours and 40 minutes. The remaining vinyl chloride is blown off and the autoclave evacuated several times in order to remove the remaining vinyl chloride. 5.5 kg of a fine-grain copolymer are obtained (sample la).

The same approach works without epoxidized soybean oil repeated (sample Ib).

The samples are packed and stored in paper bags. Samples are taken after certain times, dissolved in tetrahydrofuran and the dissolved proportions determined by weight. In Table 1 are these values specified depending on the storage time.

Table 1

storage time
months

Networking share
Sample weight%

Cross-linked portion of sample Ib% by weight

0.0
0.5
1.0
2.0
3.0

0.0 0.0 0.0 0.0 0.0

0.0

5.8

8.5

18.0

24.0

35

40

45

The sample la is without a storage tent even after two years cross-linked portions, while sample Ib is completely useless for the rest of the time after only three months of storage Processing has become 1st.

Storage in daylight accelerates the renewal process at sample Ib.

55

60

65

Example 2

Example 1 is repeated with the difference that, in the copolymerization, instead of vinyltrlethoxysl- ·

Table 2 Networked portion Networked portion storage time Sample 2a wt .-% Sample 2b wt% months 0.0 0.0 0.0 0.0 50.4 0.5 0.0 68.6 1.0 0.0 73.4 2.0 0.0 76.2 3.0

lan vinyltrimethoxysilane is used. Sample 2a is carried out with the addition of the specified amount of epoxidized soybean oil, sample 2b without epoxidized soybean oil.
Table 2 shows the results.

Example 3

In a 1-1 glass autoclave with a puffing propeller stirrer (800 rpm), with the exclusion of oxygen, 380 g of vinyl chloride, 20 g of vinyltriethoxystlan, 12 mg of a dispersion of copolymers of vinyl acetate as Rornblldner and 32 mg of acetylcyclohexanesulphone peroxide and 4.0 grams of epoxidized soybean oil. After a polymerization time of 2 hours the excess vinyl chloride evaporated and the copolymer washed with methanol and in vacuo dried (sample 3a).

The same approach is repeated, but without the addition of epoxidized soybean oil (sample 3b). The approach corresponds to a recipe of the first stage of a two-stage mass polymerization of vinyl chloride. Sample 3a contains no crosslinked portions, while sample 3b contains 10.8% crosslinked portions.

Example 4

In a 1-1 glass autoclave with a ribbon mixer (rpm 150) are introduced with the exclusion of oxygen: 37.5 g of vinyl esters of branched, saturated monocarboxylic acids with C, Cio and Cn side chains and tertiary COOH groups, 12.5 g vinyltrlethoxylane, 12.5 g dicyclohexyl fumarate, 187.5 g vinyl chloride, 5.0 g epoxidized Soybean oil, 1.25 g dicetyl percarbonate and 250 g ethyl acetate. The polymerization tent is six hours at a polymerization temperature of 48 ° C. After this time 140 ecm of ethyl acetate pumped into the autoclave and the remaining vinyl chloride removed. A clear lacquer solution is obtained, which has not yet changed its viscosity after six months. Without the addition of epoxidized soybean oil gelation occurs after just eight days. The solution is no longer for application to substrates suitable.

The experiments run in a similar way if the epoxidized soybean oil is replaced by glytidyl acrylate, 2,3-epoxy-butane, Bls-glycldyl ether of 4,4'-Dlhydroxydlphenyl-dlmethyl-methane replaced.

Example 5

In a 20 l steel autoclave equipped with a stirrer at the edge, after removal of the oxygen 5000 g of a monomer mixture of 92.5% by weight of vinyl chloride and 7.5% by weight of vinyl tri-tert-butoxy-silane, 45 g of 2,3-epoxy-butane and 40 g of Dllauroylperoxid added and polymerized at 55 ° C under autogenous pressure. In the In Yield of 85% of the copolymer obtained, no crosslinked proportions were found.

B e 1 s ρ I e I 6

The following are introduced into a 1-1 glass autoclave flushed with nitrogen: 420 ecm H ₂ O, 19 ecm 30% methyl cellulose solution, 11 g vinyltrlethoxylane, 1.5 g glycldyl ester of acrylic acid, 1.43 g dicetyl percarbonate and 209 g vinyl chloride. The autoclave is heated to 50 ° C. and stirred with a propeller stirrer (500 rpm). After 21 hours, 200 g of copolymer are obtained. The crosslinked proportions were only 3.5%, while 65% crosslinked proportions were contained without the addition of glycldyl acrylate.

Claims (2)

Patent claims: 1. Method of preventing crosslinking when carried out under normal conditions Copolymerization of vinyl chloride with vinyltrialkoxysilanes and optionally others with vinyl chloride copolymerizable ethylenically unsaturated monomers in the presence of free radical-forming Catalysts and optionally customary additives, characterized in that the Adding polymerization batch before or during the copolymerization 1,2-epoxides. 2. The method according to claim 1, characterized in that the copolymerization in aqueous Phase.