DE1520171B2 - Process for the production of silicon-containing propylene polymers - Google Patents

Description

R '

R "- SiH
R '"

35

40

R '

SiH,

RSiH
in which R is alkyl or alkoxy radicals and η ³

an integer greater than 2 means under

atmospheric or elevated pressure, in which R, R ', R "and R'" are alkyl, aryl or alkoxy

characterized in that as radical or halogen atoms mean, or one

Aluminum compound an organoaluminum cyclic or linear polyorganohydrosiloxane

Connection used. the following general formulas

It is known that propylene or other alpha-olefins can be converted with the aid of Ziegler-Natta catalysts can polymerize to stereoregular polymeric products; is of particular interest isotactic polypropylene in the form of synthetic fibers. However, this product doesn't just have numerous Advantages, but also, as a fiber, many disadvantages in terms of its sensitivity to heat and ultraviolet rays and their difficult colorability; there has therefore not been a lack of attempts to remedy these shortcomings.

For example, heat resistance could be improved by using the remaining Catalyst components completely extracted from the product. Furthermore one has to prevent-R, Si-O-

-Si-O

R.
-Si-O

-SiR,

in which R is alkyl or alkoxy radicals and η is an integer greater than 2, under atmospheric or elevated pressure, which is thereby marked

It is shown that an organoaluminum compound is used as the aluminum compound.

The mentioned silicon compounds with the silicon-hydrogen bond are in the present case capable of being used as an additive to Ziegler catalysts to accelerate the rate of polymerization and, in addition, a silicon component in introduce the polymer produced. The inventive Process thus leads to a copolymerization of propylene and the silicon compounds used, in other words, to a new type of propylene polymer, the »silicopolypropylene«.

The organic monosilanes mentioned are usually by the hydrogenolysis reaction of Halogenosilane or alkoxysilane obtained with metal hydride or from the by-product of methylchlorosilanes using the so-called direct synthesis process, based on metallic silicon is reacted with methyl chloride.

Silicochloroform can be used as a catalyst component, but is less suitable because it contains 3 chlorine atoms in one molecule and therefore affects the Ziegler catalyst through undesirable cationic behavior. Very dangerous explosive substances can also arise if the two components of the Ziegler catalyst are mixed in the silicochloroform. It is therefore more favorable to use trialkoxysilane HSi (OR) ₃ , which is produced by alcoholysis of silicochloroform with various alcohols.

The alkylsilanes of the formulas R ₂ SiH ₂ and R ₃ SiH, in which R is alkyl, are obtained in good yield when silicon oxyhydride, the hydrolysis product of silicochloroform, is reacted with various aluminum alkyls (U.S. Patent 3,004053 and British Patent 876,708 ).

The cyclic and linear polyorganohydrosiloxanes are produced either by partial hydrolysis of trialkoxysilane or by complete hydrolysis of methyldichlorosilane CH ₃ SiHCl ₂ or by mixed hydrolysis of dimethyldichlorosilane and methyldichlorosilane or by mixed hydrolysis of methyldichlorosilane and trimethylchlorosilane.

Triethylaluminum and titanium tetrachloride are commonly used as the Ziegler catalyst components used, but other alkyl aluminum halides of the formula

R _n Al ₂ X _6. ,,

in which X denotes halogen and η denotes integers from 1 to 5, are effective, especially when they are used together with those organosilicon compounds which contain siloxane or alkoxy groups; these have a moderating effect on the cationic nature of the catalyst by exchanging halogen atoms between aluminum and silicon atoms.

The type of mixing and the proportions of the three components can be varied somewhat, however the three components are generally introduced into the polymerization phase at the same time. A too long time between mixing the silicon compound with the titanium tetrachloride is reduced the activity of the catalyst, because the silicon-hydrogen bond is easily cleaved.

The same reaction occurs when the catalyst mixture is heated so that external heating is not necessarily required, because when the three components of the catalyst are mixed, heat is already generated.

With regard to the quantitative ratio of the three components, kinetic investigation of these Polymerization reaction found that there was an optimum range (published in J. Polymer Science Vol. 57, pp. 837 to 854 [1962], Collective column of the Symposium International Macromolecular Chemistry).

The mechanism by which silicon is introduced into the polymer formed may be as follows Equation can be formulated:

CH,

I (+)
Si - O

(+) <)
M CH ₂ -CH- polymer residue

CH ₃

_M <+> _H (-> CH ₃ SiCH ₂ -CH - polymer _{residue CH 3}

The metal hydride M ⁽⁺⁾ H ⁽ 'can, as long as it exists and adds monomeric propylene, be recycled, but the silicon-hydrogen bond as the end unit of the polymer chain is gradually consumed. The yield of polymer is increased for as long the amount of silicon compound used is increased up to the same molar ratio of the component to the titanium tetrachloride, but too large an excess of the silicon compound can cause the waxing process to end too early and reduce the molecular weight of the polymer are used, the added organoaluminum compound is reduced in its reactivity by complex formation with the siloxy bond.

weakens. .

There is therefore an optimal range for the amounts used, and in the case of polymethylhydrosiloxane, for example, the molar ratio of the siloxy unit to the titanium tetrachloride is expediently chosen to be 1: 1. The higher ratio of triethylaluminum to titanium tetrachloride also has an optimal value in this three-phase catalyst system. According to the experimental results of the kinetic investigations, it is between 10: 1 and 10: 3: 3 for an appropriate range. ; _:

It is generally desirable to carry out both the catalyst formation reaction and the subsequent polymerization reaction in an inert thinners, e.g. B. a saturated hydrocarbon; hydrogen, such as hexane or heptane, and with introduction. a stream of gaseous propylene. into the reaction phase under atmospheric pressure

respectively. However, it is more convenient to work under pressure in an autoclave, which reduces the rate of polymerization strengthens is increased. Even if the gas is introduced under atmospheric pressure this ternary catalyst system can increase the rate of polymerization with the addition of the silicon compound double that of Ziegler catalysts. But if you work under pressure, you can Significantly increase propylene concentration and even mass polymerization as an extreme case of one Carry out solvent-free phase because the liquid phase of the monomeric propylene as the suspension medium act for the catalyst and the polymer precipitate. So you become a liquid A, made by mixing the silicon component with the titanium tetrachloride in liquid monomers and a liquid B, which is a solution of the organoaluminum compound is in liquid monomer or an organic solvent, continuously in a predetermined Volume ratio of the two liquids through two different feed lines into the cylindrical, Introduce a reaction vessel equipped with a stirrer. Then the polymerization reaction takes place takes place without delay at the point where the two liquids meet in the vessel, and when an extruder is used as a discharge device for this reaction system, Silicopolypropylene is continuously produced by this plant. The optimal temperature at these The process is roughly in the range between 40 and 70 ° C. It is therefore necessary to open the reaction zone effective to cool and keep the temperature uniform because of the rapid reaction generated Heat of polymerization can be great.

The catalyst remaining in the resulting polymer still has a certain activity if it is also weak compared to the original one. When this active polymer blend further monomer is fed in, further polymerization often occurs; the active polymer mixture One reaction mixture can therefore be used as a catalyst material in another reaction vessel will. In this way, the greatest possible utilization of the catalyst activity is possible.

The mixture obtained during the polymerization is then mixed with water, acid or an acid-alcohol mixture decomposed, as is usual with the decomposition of Ziegler catalysts. It is essential easier to remove titanium and aluminum catalyst parts from silicopolypropylene than from the ordinary Polypropylene. In particular, titanium residues adhere in the known, from Ziegler or Natta catalysts produced polypropylene sticks to the polymer, and it is very difficult to completely remove. They cause sensitivity to sunlight and poor heat resistance. The whiteness of the silicopolypropylene is excellent, and its resistance to ultraviolet Radiation is also superior to that of ordinary polypropylene. Furthermore, it withstands temperatures for a long time near its melting point with no decomposition and almost no discoloration.

The proportion of silicon components in the silicone polypropylene can be between 0.1 and 17.0 percent by weight (calculated as silicon content).

From the infrared spectra and the chemical analysis of the extracted fraction of the products Washing out the catalyst residues and extraction with solvents such as diethyl ether, n-hexane and Isooctane, it can be concluded that the silicone polypropylene is a type of graft polymer. Two IR spectra of solvent extraction fractions of the representative products of Example 1, Run 1 and 4, are shown in FIGS. 1 and 2 reproduced.

Of these, the spectrum in FIG. 2 largely corresponds to that of isotactic polypropylene, apart from the bands of the siloxane and the methyl-silicon bond, although the product Contains 1.6 percent by weight silicon. This is evidence that the silicon was grafted into the polymer and is not built into the polymer backbone.

The silicopolypropylene has a slightly lower melting range than a comparably manufactured one Polypropylene as shown in Table II. This can be due to the decrease in the degree of polymerization and due to the disturbance of the stereo regularity in the grafted chains of the polypropylene be. The silicopolypropylene shows compared to (I the known polypropylene no clear "' Melting point. The melt indices (ASTM D 1238-57 T) fluctuated when the others were examined Sample of the solvent extract from Example 1, Experiment 4, between 5 and 1.3. The usual Polypropylene, on the other hand, delivers uniform values. This indicates some bridging between the molecular chains and a decrease in the silanol group content when heated. The silanol groups present in the freshly prepared silicopolypropylene have the ability for condensation.

For example

The required amounts of triethylaluminum and titanium tetrachloride are first in 5 ml of n-hexane dissolved, and the two solutions are melted in two glass ampoules. These two ampoules are carefully placed in a 2-1 autoclave, and polymethylhydrosiloxane and 200 ml of n-hexane as solvents are introduced directly into the autoclave. After the lid of the autoclave is applied and sealed, 110 ml of liquid propylene is introduced through an inlet tube. After the reaction mixture has been adjusted to the desired temperature, is turned the stirrer to break the glass ampoules and start the reaction. A sudden rise in temperature and fall in pressure indicate the beginning of the reaction. The resulting polymer is boiled in a mixture of hydrochloric acid and methanol and washed repeatedly with methanol. A Soxhlet extraction apparatus is used for the solvent extraction of the crude product. the by changing the amounts of polymethylhydrosiloxane, triethylaluminum and titanium tetrachloride The results obtained are shown in Table I and the properties of the polymers in Table II.

F i g. 1 shows an infrared spectrum of the isooctane extract obtained according to Example 1, Experiment 1 Polymer;

F i g. Figure 2 shows an infrared spectrum of the solvent extraction residue of the polymer prepared according to Example 1, Experiment 4.

7 8

Table I Propylene Polymerization with the Three Component Catalyst System

AlAt ₃ catalyst Silicon-
component reaction time temperature Propylene solid
Polymer initial
Pressure drop attempt (ml) TiCl ₄ (ml) (H) ( ⁰ C) fluid (G) (kg / cm ² / h) 5 (ml) 5 2.5 65 (ml) 10.6 2.7 1 5 2 5 2.5 69 110 18.8 4.3 2 5 2.5 0 3.5 60 110 8.7 3.5 3 5 2.5 1 5.0 53 110 50.0 4.4 4th 5 1 5 3.1 51 110 11.0 6.9 . · 5 5 1 0.5 3.5 55 110 50.7 5.6 6th 5 1 0 5.9 55 110 49.6 3.2 7th 1 110

Note Titanium tetrachloride was reduced by powdered aluminum (0.5 g) in xylene at 130 to 150 ^° C.

Table II Properties of the polymers obtained

ether Solvent extract,% octane Not (%) extractable component Si content attempt 31.6 4.1 °) 55.2 Melting point
(° C) 16.1 1 36.0 8.8 51.7 11.1 2 14.7 3.9 78.5 147 to 155 - 3 41.3 17.4 27.8 - 1.6 4th - - - 147 to 155 16.6 ") 5 41.0 15.0 35.8 - 6th 28.3 11.0 52.7 153.5 to 160 7th 154 to 162 Hexane 9.1 ") 3.5 3.1 13.5 - 8.8 8.1

Remarks

") These extracted polymers contained silicon in an amount of 0.7% in the n-hexane extract and 3.5% in the isooctane extract. *) The unextracted polymer was used.

Example 2

Three glass ampoules containing 5 ml (4.2 g) triethylaluminum, 1 ml (1.8 g) titanium tetrachloride and solutions

Containing 1 g of triethoxysilane in 5 ml of η-hexane were placed in a 2-1 autoclave, which is the used in Example 1 was similar. Furthermore, under pressure, 200 ml of η-hexane were used as a solvent and then introduced 110 ml of liquid propylene. The temperature was kept at 50 to 55 ° C, the ampoules were broken, and the reaction became

Carried out for 2 hours with stirring. The crude polymer was in the mixture of hydrochloric acid and Methanol boiled, rinsed and dried. 51 g of a white polymer were obtained. In the solvent extract fractions A silicon component was found in the product, and this component can be found even after cooking for several hours cannot be removed in a caustic alkali solution. The infrared spectra also showed that the silicon component is grafted onto "the polypropylene chain.

Example 3

The procedure of Example 2 was repeated, except that 1 g of triethylsilane was used as the silicon compound added. The temperature was kept at 50 to 55 ° C and the reaction was taking 2 hours Stirring carried out. After thorough decomposition of the crude product and washing with acid and Methanol, 48 g of a white polymer were obtained. The infrared absorption spectrum confirmed that the silicon compound is grafted onto the polypropylene chain.

Example4

The procedure of Example 2 was repeated, except that 1 g of triphenylsilane was added as a silicon compound. The temperature was kept at 65 to 70 ^° C. and the temperature was carried out with stirring for 2 hours. After thorough decomposition of the crude product and washing with acid and methanol, 31 g of a white polymer were obtained. The infrared absorption spectrum showed the existence of phenyl silicon bonds.

From a film produced from the extract residue from Example 1, Experiment 4, the The density of the material was determined to be 0.886, which is slightly lower than that of ordinary polypropylene.

Irradiation with UV light results in less discoloration and decrease in strength than ordinary Polypropylene.

1 sheet of drawings

209 545/544

Claims (1)

Claim: Process for the production of silicon-containing propylene polymers by polymerizing the Propylene in the presence of titanium tetrachloride, an aluminum compound and at least one organic monosilane of the following general formulas R ' R "- SiH
R "'
R. SiH, RSiH ₃ in which R, R ', R "and R"' denote alkyl, aryl or alkoxy radicals or halogen atoms, or of a cyclic or linear polyorganohydrosiloxane of the following general formulas / R
Si-O
H R, Si — O- R.
-Si-O -SiR, tion of a decomposition of the product during the melt spinning process antioxidants and others stabilizing agents added. To prevent exposure to ultraviolet light and To improve the dye affinity, one has the threads or fibers or those made from them Textiles wrapped in UV-absorbing substances or mixed polymerisation with other monomers carried out under high-energy radiation. Despite these attempts, however, it has not yet been done succeeded in eliminating the listed deficiencies in a satisfactory manner. It is Z. B. from Austrian Patent 206 646 known as a catalyst in the polymerization of ethylene and alpha-olefins are the reaction product of hydrogen polysiloxanes with compounds of the metals of IV. to VI. Subgroup to use. This gives very active polymerization catalysts, and what is obtained thereby Polyethylene is free from low molecular weight components and has only a very low ash content. The invention relates to a process for the production of silicon-containing propylene polymers by polymerizing propylene in the presence of titanium tetrachloride, an aluminum compound and at least one organic monosilane of the following general formulas