DD147247A1 - PROCESS FOR PRODUCING OXYDATION-PROOF POLYMERS - Google Patents

Abstract

The invention relates to oxidation-protected polymers, copolymers and block copolymers. Effective oxidation protection is achieved by using organosilicon compounds containing antioxidant groups as terminators of anionic polymerization or copolymerization. The Antioxydansgruppen are hydrolysis resistant bound by covalent bonding to the polymer structure. They are not volatile under the conditions of plastic processing and are preferably in the surface. With minimal use of antioxidants, maximum protection against oxidative influences is guaranteed.

Description

21 29 5 0 -1-

Title of the invention

Process for the preparation of oxidation-protected polymers

Field of application of the invention

The invention relates to a process for the preparation of oxidation-protected polymers of the general formulas:

A "(G) σ (Α") ₂

(A ¹¹ G)

n = l-3

or block copolymers of the general formulas:

A "(BG)

G (BA ") ₂ (A ¹¹ BGB)

n = l-3

where A "= Antioxydansrest containing silane or siloxane B = polysiloxane block C = polyolefin block

and A satisfies the formula of the following formula:> 3

R-

Si-O

Si

*

with R = Antioxydansgruppe entlialtender remainder, partially by

R can be replaced

R = hydrolyzable group R- ^ = alkyl or aryl radical η = O-2o

2129 5 0 - 2 -

Analogous compounds with trifunctional silane units, or with only one hydrolyzable group can be used in the same way.

The Antioxydansgruppeη are hydrolysis resistant anchored with covalent bond in the polymer structure. They are preferably in the surface of the polymer and do not volatilize during a subsequent e.g. shaping, whereby a maximum protection of the polymers against oxidative influences is ensured with low use of antioxidants.

Characteristic of the known technical solutions

In the art, the stabilization of polymers is usually accomplished by physical admixing of antioxidants, such as ionol. Due to the high volatility, however, the applied substances tend to exude to a considerable degree during thermal processing. Therefore, an attempt was made to develop less volatile, relatively high molecular weight compounds or to link the antioxidant with the polymer to be protected via covalent bonds. A technical solution has been used in the synthesis of relatively high molecular weight compounds, such as

si ph ₍₄ _ _d)

(Pietrovskii, K. B., Ronina, M.P., Bannikov, G. F., Nikiforov, G. A. Ershov, V. V., Izv Akad Hauk SSSR, Ser. Khim., 11 (1976) 24-50-3). Principally similar compounds are described in the patents USSR 395 414; USSR 463,683, USSR 468,942, USSR 455,131 and US 3,823,114. However, the Si-O-G bonds are not stable to hydrolysis. Therefore, upon access of atmospheric moisture, low molecular weight residues of the protected compounds are formed, which have a similar high volatility as das.o.g. Ionol. An improvement of this method was achieved by the combination of organic and silicon-organic MoIeMiI

212950

share about% - ^ ~ bindings. For example, Albarino (Albarino, R.V., Schonhorn, H, J. Appl. Polym., 1374, 18 (3) 6354-9) describes compounds having, in addition to the antioxydant, amino groups. Hydrolysis of the latter groups produces an antioxidant-containing network with greatly reduced volatility. However, this siloxane network is incompatible with most organic polymers.

As higher molecular weight silicon-free antioxidants u.a. Polyalkylene glycol esters of hindered phenols (US Pat. No. 2,944,594), the polycondensation product of

(Japan 74 45, 060), Polyäthinylpyridin (USSH 302 014) and many other compounds proposed.

Another technical solution is to connect the Antiosqydans via covalent bonds directly to the polymer to be protected by polymerizing it. In the British patent ITr. 1 402 720 is the copolymerization of the compound.

OCOO = CII ₂ CH.

protected with styrene and butadiene. Also the connections

, GMe. CII ₂ = C - CO ₂

me

CMe ₀

(US 3,629,197) and

CMe.

CH ₂ = CHOCH ₂ CH ₂ OC

212950 _ ₄ _

(Kato, M., J. Polymer, Vol., Biol. (1972) 489 and 157) were polymerized in a free-radical fashion. Similar compounds were linked by Ziegler-Natta polymerization with the polymer to be protected (US 3,477,991). Another possibility for the firm anchoring of antioxidants in polymers was found by Petrov. He employed "living" polymers with a Schiff's base acting as an antioxidant (Petrov, G., et al., Vysokomol., ³ oedin, Ser., B £ (1975) 6, 429-32).

The disadvantage of said copolymerized or higher molecular weight antioxidants is that they are only at a low level on the surface of the polymer where they have their main activity, i. a large part of the antioxidant contained in the polymer remains ineffective. An overcoming of this disadvantage reached Evans by grafting a sterically hindered phenol of the formula

CH ₂ OGOGH =

on a thin polypropylene film. He thus ensured that the antioxidant is on the surface of the polymer. (Evans, B.W., Scott, G. European Polym., J. 10 (1974) 453) · However, the antioxidant can be introduced here only after the deformation, which is not economically feasible on an industrial scale. A further disadvantage is that with mechanical abrasion of the surface no antioxidant can be replenished.

Object of the invention

The aim of the E _r invention to produce against oxidation polymers, copolymers or block copolymers. The Antioxydansgruppen should be bound hydrolytically stable with covalent bond in the polymer structure. They should preferably be located on the surface of the polymer and also in a subsequent thermal treatment, such as shaping,

2 129S0 _

do not volatilize, should be achieved with a relatively low proportion of antioxidant maximum protection of the polymers from oxidative influences.

Explanation of the essence of the invention

The invention involves synthesizing polymers with antioxidant residues in which the antioxidant is hydrolytically stable and non-volatile during processing, and where the antioxidant is preferentially located in the surface layers. The object is achieved in that the Antioxydansrest is bound via an organosilicon radical to a polymer. The inventive method consists in an anionic polymerization or copolymerization of olefins or of olefins and C3 ⁷ clischen siloxanes and the termination of the polymerization with reactive, antioxidants containing silicon compounds. The anionic polymerization is preferably carried out in aprotic (eg hexane) or aprotic dipolar solvents (eg tetrahydrofuran). The polymerization temperature is preferably from - 80 to + 50 ⁰ G. As the initiator organometallic compounds of the 1st ^ to 3 x main group of the Periodic Table (eg Li lkyle ^A) or Alkalimetallaromaten warden used (for example, Ta or • K-naphthalene).

In the polymerization or copolymerization of the olefins, such as, for example, styrene, butadiene or acrylonitrile, polymer ions CO or dianions C. In the copolymerization of the olefins with cyclic iloxanen, such as hexamethylcyclotrisiloxane (Do) or Olcbamethylcyclotetrasiloxan (D ₂ ,), depending on the initiator used polymer anions of the type CB "or ~ BCB ~ (B = PolysiIoxan, C = polyolefin) with . Silanolatendgruppen This Polymermono- or dianions be at room temperature with mono-, di- or tri-functional silicon compounds as antioxydanshaltigen Fig _reC h _he implemented .Products This caused the general l ^ormeln...?:

A "(BO) _n '

C (BA ¹ O ₂

CA "BCB) ₄

212950

(A "= antioxidant-containing B" = polysiloxane block C: = polyolefin block)

ITm the inventive Siliziuniabbrecher the general formula ο o

β? ^ny

R ² - (SiO) _n -Si - R ² 11

R R

are obtained, by known methods Antioxydansreste connected with reactive ilanen, for example, can be introduced by dehydration or etherification C =: G double bonds in the Antioxydansmolekül and halo-alkoxy or Acyloxyhydrogensilane be added to these double bonds. The silicon compounds described can be partially hydrolyzed with a water solvent mixture to oligo- or polysiloxanes with hydrolyzable end groups. The described Antioxydansgruppen sustaining silanes or siloxanes the "living ¹¹ polymer chains are broken, advantages of this process are the Mchtflüchtigkeit of antioxidant, his hydrolydestabile linking with the polymer, and the enrichment of the stabilizer on the surface of the polymer. For the last requirement may result from the Literature shows that the outer layer of a polystyrene polydimethylsiloxane copolyineren consists of pure polydimethylsiloxane (Clark, DT, Dilks, A., Peeling, J., Thomas, HR Faraday Discuss, Chem. Soc., 60 (1976) 183-95 ). Since according to the invention the a _n tioxydans is in Süoxanteil, is secured to the surface of a high concentration of antioxidant.

The advantages mentioned represent a technical advance of the hitherto known solutions.

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Example 1: Preparation of polystyrene of the type (A ¹ OpG

7.9 g (7.58 x 10 ^-2 mole) of styrene,? Earth 0.097 g (1.52 χ 10 "" ³

Mol) of η-butyllithium (dissolved in 0.5 ml of hexane) as an initiator in THP at -78 ⁰ G anionically polymerized under completely inert conditions.

Subsequently, with the antioxidant prepared by addition of methyldichlorosilane to the allyl ether of 2,6-di-t-butylhydroquinone, (a) or dimethyldichlorosilane (b) is stopped.

For workup, the polymer solution is precipitated with methanol and reprecipitated.

The polymers are dried one-o'clock in a vacuum oven.

= 10,400

% Antioxidant: 2.1

Results of DTA examinations of polystyrenes, MW: 10,400

Sample decomposition start weight loss

0 - 310 ⁰ C

a 300 3.0

b 235 18.5

a - Ionol chemically anchored b - without stabilizer

Example 2; Preparation of Polystyrene Oil Polydimethylsiloxane Copolymers of 'iyps A' (BG) o

15.64 g (0.15 mol) of styrene with 0.04 g (6.3 x 10 " ⁴ " mol) of n-butyl lithium) dissolved in 0.5 ml of hexane as an initiator in SHP at - 78 ⁰ C under completely anionically polymerized inert conditions. Subsequently, 15 ^ 54 g (0.07 mol) of hexamethyl cyclotrisiloxane (Do), dissolved in 40 ml of ¹ I ¹ HF, always tempera ture added at Z, and the mixture heated to 30 ⁰ G. After completion of the copolymerization with the antioxidant prepared by addition of methyldichlorosilane to the acyl ether of 2,6-di-tert-butylhydroquinone (a) or dimethyldichlorosilane (b)

(c) aborted ·

For workup, the polymer solution is precipitated with methanol, treated with hexane to dissolve out homopolysiloxane, and

overturned again »

The polymers are a ^ eek at about 60 ⁰ C in a vacuum oven dried.

M _n ι 105 300

% Si: 17.35.

% Antioxidant: 0.21

Results of DTA Studies of Polystyrene-Polydimethylsilozane Gopolymers, MW: 105,300.

Sample decomposition start weight loss

0-310 ⁰ G / ⁰ O / /% /

a 310 0.9.

b 285 5.1

0 276 7.3

a - ionol anchored chemically

b - ionol physically mixed

c- without stabilizer

Example 3: Preparation of polystyrene-polydimethylsiloxane copolymers of the type G (BA ^M ) _?

15.64 g (0.15 mol) of styrene are mixed with 0.21 g (1.26 χ 10 " ³ mol) of K-naphthalene (dissolved in 1 ml of THF) as an initiator in THF at -78 ° C under completely inert polymerized anionically conditions. Subsequently, 15,64- g (0.07 mole) of hexamethylcyclotrisiloxane (Do) dissolved in'4-0 ml THF was added at room temperature and the mixture heated to 30 ⁰ g. F ^ alas end of the copolymerization is with the antioxidant prepared by addition of dimethylchlorosilane to the any ether of 2,6-dit-butyl-hydu-quinone or trimethylchlorosilane was quenched, for work-up see Example 2

M _n: 100 000% Si: 18.9

Example 4: Preparation of polybutadiene-polydimethylsiloxane copolymers of the type A "(BG) ₂

27.8 s (0.51 mol) of butadiene are with 0.073 S (1.15.x 10 "" ³ mol) n-utyllithiuci (dissolved in 0.5 ml of hexane) as an initiator in hexane at + 50 ⁰ C under anionically polymerized under completely inert conditions. Subsequently, 6.88 g (3.09 x 10 mol) D ^ * dissolved in 40 ml TIiP, are added and the mixture is heated to 30 ⁰ G.

After completion of the copolymerization is stopped with the antioxidant, prepared by addition of methyldichlorosilane to the allyl ether of 2,6-di-t-butylhydroquinone, or dimethyldichlorosilane.

For workup, the polymer solution is precipitated with methanol and reprecipitated. The polymers are dried for about one week at about 60 ⁰ G in a vacuum oven.

Example 5: Preparation of polybutadiene-polydimethylsiloxane copolymers of the type

28.5 S (0.53 mol) of butadiene with 0.3 g (2.2 χ 10 ~ ³ mol) of Na-naphthaiin (dissolved in 1 ml of THB ¹ ) as an initiator in THB ¹ at - 78 ⁰ G under completely anionically polymerized inert conditions. Subsequently, 3.18 g (1.43 x 10 ^-2 mole) of D _3, dissolved in 40 ml THF was added at room temperature and the mixture + 30 ⁰ G heated. -

After completion of the copolymerization is terminated with the antioxidant, prepared by addition of dimethylchlorosilane to the allyl ether of 2,6-di-t-butylhydroquinone, or trimethylchlorosilane

 Workup see Example 4,.

Claims (1)

claim A process for the preparation of oxidation-protected, obtained by anionic polymerization olefin polymers, copolymers or block copolymers, characterized in that the anionic polymerization as mono- or Dianio'nen resulting polymer chains with organosilicon compounds containing the antioxidant organosilicon compounds of the general formula SiO R ¹  5 T? Si where mean R = group containing antioxidant group which is partially can be replaced by R ^ R = hydrolyzable group R · ^ = alkyl or aryl radical
η = 0-20 be implemented as a chain terminator · Process according to item 1, characterized in that before the chain termination with the organosilicon compounds containing antioxidant groups, the olefin polymer mono- or dianicpenes are copolymerized with antioxydant group-free organosilicon compounds or organosiloxane blocks.