DE3606984A1 - Polysiloxane-containing block copolymers - Google Patents

Abstract

The invention relates to novel block copolymers comprising recurring structural units from the series consisting of the polysiloxanes, and recurring structural units from the series consisting of the homopolymers, copolymers or terpolymers of vinylaromatic compounds and acrylic monomers, or mixtures thereof.

Description

The invention relates to new block copolymers from recurring Structural units from the series of polysiloxanes and recurring structural units from the series of Homopolymers, copolymers or terpolymers of vinyl aromatics and Acrylic monomers or mixtures thereof.

Various block copolymers are known, e.g. B. Styrene-butadiene block copolymers, block copolymers from aliphatic Polyesters or polyethers and polyesters of aromatic dicarboxylic acids or block copolymers on the Aromatic polycarbonate base.

Block copolymers, on the other hand, are relatively little known, where the polymer blocks are made of polysiloxane units and from radical polymerization Units are built.

It has been found that block-like polymers are based on Basis of polysiloxanes and segments that differ from homo-,  Copolymers or terpolymers of vinyl aromatics and acrylic compounds or derive their mixtures, particularly interesting Can have properties such. B. good flexibility, especially at low temperatures.

The invention relates to polymers with block-like Structure from structural units (I)

-A- (I)

and structural units (II) and / or (III)

[B- (II)
-B- (III)

wherein the polymers have average molecular weights ( M _w ) of 2,000 to 500,000, preferably 5,000 to 250,000, characterized in that

• - A represents a bifunctional polysiloxane segment of the formula (IV) - ¹ ) (R ² ) SiO- _x , 6 (IV), with R ¹ and R ² = aryl and / or alkyl, where x represents such a number that (IV ) Has molecular weights ( M _w ) of ≦ λτ500, preferably ≦ λτ750, and
• B represent mono- or bifunctional homo- and / or co- and / or terpolymer segments based on monomers from the series of the monovinyl aromatics and the acrylic compounds or mixtures thereof, these segments being molecular weights ( M _w ) ≦ λτ800, preferably ≦ λτ1 .000, have.

The segments B of the block copolymers according to the invention are composed of those containing hydroxyl groups in the presence Mercaptans radically polymerized monomers selected from vinyl aromatics, such as. B. styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, halostyrene, and from acrylic monomers such as B. (meth) acrylonitrile, (meth) acrylic acid ester with 1-12 C atoms in the alcohol component, e.g. B. Methyl methacrylate, n-butyl acrylate or mixtures of both types of monomers.

Polymers of styrene, α-methylstyrene, Acrylonitrile, methyl methacrylate or mixtures from it, which polymerizes in the presence of mercaptoethanol were.

Another object of the invention is a method for the production of the block copolymers according to the invention, which is characterized in that a homo- and / or Co- and / or terpolymer made from vinyl aromatics and acrylic compounds or mixtures thereof with one or two terminal hydroxyl groups of the formula (V) or (VI)

B-OH (V)
HO-B-OH (VI)

and a polysiloxane of formula (VII)

R ³ COO- (R ¹ ) (R ² ) SiO- _x COR ³ (VII)

with R ¹ = aryl (in particular phenyl) or alkyl (in particular methyl), R ² = alkyl (in particular methyl) or aryl, R ³ = C ₁ -C ₁₈ -alkyl, x = integer, if appropriate with catalysis or by means of acid-binding agents , polycondensed with elimination of the acid R ³ COOH, the polymer (V) or (VI) having an average molecular weight ( M _w ) from 800 to 20,000, preferably from 1,500 to 15,000, and the polysiloxane (VII) having an average molecular weight ( M _w ) from 500 to 20,000.

The polysiloxanes contained in the block copolymers are Polydialkyl, polydiaryl or polyarylalkylsiloxanes, in particular Polydimethylsiloxane or polymethylphenylsiloxane Leftovers. They have block molecular weights from 500 to 20,000, especially 800 to 15,000, they are largely linear.

The polymer segments forming the blocks B are derived from Polymers made from vinyl aromatics (especially styrene, α-methylstyrene) or acrylic compounds (especially (meth) acrylonitrile, Methyl methacrylate) or mixtures thereof.

They are prepared by radical polymerization of these monomers in the presence of suitable amounts of hydroxyl-containing mercaptans to adjust the desired molecular weight. Examples of such compounds are mercaptoethanol (HO-CH ₂ CH ₂ -SH), mercaptopropanol, mercaptobutanol, mercaptophenol.

The production of the polymer segments leading to blocks B. can according to the known methods of radical Polymerization e.g. B. in bulk, in solution, in emulsion or in suspension or by a combination of these methods respectively; suitable free radical initiators are organic Peroxides, e.g. B. benzoyl peroxide, cumene hydroperoxide, or inorganic peroxides, e.g. B. potassium peroxide or Hydrogen peroxide, with suitable initiators also introduced a terminal hydroxyl group into the polymer chain can be, inorganic persulfates such. B. potassium persulfate, Azo initiators such as B. Azobisisobutyronitrile as well as redox systems consisting of an oxidizing agent, preferably a peroxide, and a reducing agent.

The polymerization reaction can take place in a wide temperature range be carried out, preferably it is carried out between 30 ° and 100 ° C, particularly preferably between 50 ° and 80 ° C.

The block copolymers according to the invention can be produced by using bisacylated polysiloxanes of the formula (VII) with homopolymers and / or copolymers and / or terpolymers Vinyl aromatics or acrylic compounds or mixtures thereof with one or two terminal hydroxyl groups Formula (V) or (VI) polycondensed. Usually will  the starting components of the formulas (V) and (VII) or (VI) and (VII) used in equimolar amounts, it can but also be advantageous one or the other component use in small excess. You can do that Control final molecular weight better and the type of end groups determine. To the molecular weight at the To determine synthesis, one can use molecular weight regulators use, e.g. B. monofunctional compounds such as mono alcohols, monoacylated polysiloxanes, anhydrides, esters and Acid chlorides.

The block copolymers can be synthesized at temperatures from 40 to about 200 ° C, in particular at 80 to 150 ° C. It can be with or without solvent to be worked, e.g. B. with aromatic hydrocarbons, Paraffins, chlorinated hydrocarbons, liquid amides, esters, ketones or ethers.

A preferred embodiment of the method starts without solvent and adds solvent at the end of the Polycondensation too.

Catalysts and / or acid-binding agents are preferably used Means, e.g. B. organic or inorganic bases such as salts (Carbonates of alkali or alkaline earth metals) or soluble organic bases, such as tertiary amines, also phase transfer catalysts, Phosphines, Lewis bases are suitable. Under certain circumstances at certain reaction temperatures also working in the presence of catalytic amounts strong acids beneficial, especially if you the polycondensation with distillation of the formed Acids.  

The synthesis can be carried out batchwise or continuously perform, also in kneading units or Screw units.

It is also advantageous to determine the total amount of the starting substance (V) or (VI) or (VII) and - depending on the progress of the reaction - the remaining amount the different starting components (VII) or (V) or (VI) to meter in.

Following the synthesis, the block copolymers, optionally with evaporation of the auxiliary solvent or filtering off the acid that is split off isolate formed products, and by common antioxidants or stabilize light stabilizers.

The block copolymers according to the invention have good ones mechanical properties, especially at low temperatures, good chemical and solvent resistance and are, optionally in a mixture with other polymers, suitable for thermoplastic processing.

example 1 Production of a styrene / acrylonitrile copolymer with terminal hydroxyl groups

70.56 parts by weight of styrene, 27.44 parts by weight of acrylonitrile, 2 parts by weight of mercaptoethanol and 3 parts by weight of tert-butyl perpivalate are dissolved in 280 ml of ethylbenzene and 7 hours heated to 70 ° C for a long time. After removing the solvent and drying a polymer (yield 88%) with a sulfur content of 0.90% by weight and an intrinsic viscosity of 12 ml / g (in dimethylformamide at 25 ° C)

Example 2

49 parts by weight of styrene, 49 parts by weight of methyl methacrylate, 2 parts by weight of mercaptoethanol and 3 parts by weight of tert-butyl perpivalate are dissolved in 300 ml of ethylbenzene and 7 hours heated to 70 ° C for a long time. After removing the solvent and drying a polymer (yield 86%) with a sulfur content of 0.85% by weight and an intrinsic viscosity of 8.5 ml / g (in dimethylformamide at 25 ° C).

Example 3

760 parts by weight of the polymer from Example 1, 400 parts by weight of an α, ω-bis-acetylated polydimethylsiloxane with a molecular weight of 4,000 (determined by acetyl determination), 50 parts by weight of Na ₂ CO ₃ and 3,000 parts by weight Parts of toluene are reacted at 110 ° -120 ° C for 5 hours. It is then cooled, filtered and the solvent is distilled off. The resulting product has an intrinsic viscosity of 21 ml / g (in chlorobenzene at 25 ° C).

Example 4

Example 3 is repeated, 800 parts by weight of the polymer from Example 2 being used while maintaining the amounts of α, ω-bis-acetylated polydimethylsiloxane, Na ₂ CO ₃ and toluene. The resulting product has an intrinsic viscosity of 17.5 ml / g (in chlorobenzene at 25 ° C).

Claims (4)

1. Polymers with a block-like structure of structural units (I) -A-, 6 (I) and structural units (II) and / or (III) [B-, 6 (II) -B-, 6 (III), the polymers being medium Have molecular weights ( M _w ) of 2,000 to 500,000, characterized in that

• - A represents a bifunctional polysiloxane segment of the formula (IV) - (R ¹ ) (R ² ) Sio- _x (IV), with R ¹ and R ² = aryl and / or alkyl, where x represents such a number that (IV ) Has molecular weight ( M _w ) of ≦ λτ500 and
• - B represent mono- or bifunctional homo- and / or co- and / or terpolymer segments based on monomers from the series of monovinyl aromatics and acrylic compounds or mixtures thereof, these segments having molecular weights (M _w ) ≦ λτ800.

2. Polymers according to claim 1, characterized in that that segment B is a mono- or bifunctional residue from the series of homopolymers, copolymers or terpolymers from Monomers from the series (α-methyl) styrene, (meth) acrylonitrile, Represents methyl methacrylate. 3. Process for the preparation of polymers according to Claims 1 and 2, characterized in that homopolymers and / or copolymers and / or terpolymers made from vinyl aromatics and acrylic compounds with terminal hydroxyl groups (V) or (VI) B-OH, 6 ( V) HO-B-OH, 6 (VI) and a polysiloxane of the formula (VII) R ³ COO- (R ¹ ) (R ² ) SiO- _x COR ³ , 6 (VII) polycondensed with elimination of the acid R ³ COOH , where R ¹ and R ² = alkyl and / or aryl, R ³ = C _1-18 - alkyl and x are an integer and where the compounds (V) and (VI) average molecular weights ( M _w ) of 800 to 20,000 and the compound (VII) have average molecular weights ( M _w ) of 500 to 20,000. 4. Use of the polymers according to claims 1 to 3 for Production of blends with other polymers.