CS212679B1 - Polyolefins are particularly polyethylene and polypropylene stabilized against thermal degradation and oxidation - Google Patents

Abstract

Polyolefins containing 0.01 to 5 wt. % di-(alkylphenyl)β-thiodipropionates of formula I together with antioxidants of phosphite and phenolic type are characterized by stability to thermal oxidation. Fields of application: Production and processing of polymers, production of motor oils. Chemical formula: Number of the subject that best characterizes the invention: 1. The invention is very easy to implement from accessible raw materials β,β' thiodipropionic acid and the corresponding substituted phenol by esterification, reesterification or via dichlorig acid. Its effect will be manifested mainly in the replacement of relatively unavailable n- alcohols used in dialkylthiodipropionates by more accessible alkylphenols. It will be possible to use it mainly in the field of processing polymers, especially pistons, or in the stabilization of oils against oxidation.

Description

The invention relates to polyolefins, especially polyethylene and polypropylene, stabilized against thermal degradation and oxidation by diphenyl or dialkylphenyl β, β'-thlodipropionates in combination with phenolic and phosphite antioxidants.

It is known that polyolefins undergo degradation under the influence of increased temperature and oxygen.

They are used to prevent degradation! antioxidants and synergistic mixtures. One of the most widespread synergistic antioxidants used for thermal stabilization are dialkyl esters of β, β -thiodipropionic acid.

Dialkyl esters of β,/-thlodipropionic acid are used together with other phenolic or phosphite antioxidants as effective synergistic additives to prevent thermal and thermal oxidative degradation. When preparing them, however, it is necessary to start from raw materials that are hard to access, pure fatty alcohols.

These disadvantages are eliminated by the invention of polyolefins, especially polyethylene and polypropylene, stabilized against thermal degradation and oxidation containing 0.01 to 5.00% by weight of diphenyl or dialkylphenyl-β, /J'-thiodipropionate of the general formula I,

II /CHgCHg—C —O—(CO ch ₂ ch ₂ —c—o—(CQ o (I)

2 · where R and R are the same or regular or branched alkyls with 1 to 24 carbon atoms and n = 0 to 4 and 0.01 to 5 weight percent of one or more antioxidants of the general formula II to IX, »2

HIM

O/—CH ₂ CH ₂ COO—R ¹ (II)

3 * where R , R , R are the same or orthonormal or branched alkyl with 1 to 18 carbon atoms, (” ⁴ )η where R ⁴ is normal or branched alkyl with 1 to 50 carbon atoms an = 0 to 4, r2 ^HO gOy—ch ₂ ch ₂ cooch ₂ (IV)

3 where R and B have the above meaning

(V) (VI) where r', R ² and R ^J are as defined above

OH OH

OH

(VIII) where R ¹ is normal or branched alkyl with 1 to 18 carbon atoms, aralkyl with 7 to 36 carbon atoms and n = 1 to 3, (R ¹ >n /OC ^H 2\ /h ₂ o w-°-< χ >OCH ₂ ^Z XH ₂ O ^Z (R ¹ ) _n (IX) where R ¹ is normal or branched alkyl with 1 to 18 carbon atoms, aralkyl with 7 to 36 carbon atoms and n = 1 to 3.

The invention is based on the finding that polyolefins can be stabilized - in combination with phenolic and phosphite antioxidants - not only by dialkyl esters of β, //-thiodipropionic acid, but also equally effectively by diphenyl or di(alkylphenyl) β, //-thiodipropionates.

The total concentration of both components ranges from 0.02 to 6 wt. % of polyolefin, especially their relative ratio depends on the type of phenolic or phosphite antioxidant of the general formula II to IX used, on the required degree of thermal and thermal oxidation stability. Polyolefins, which are the subject of the invention, can be prepared by conventional incorporation of compounds of general formula I and compounds of formulas II to IX into unstabilized polymers either directly in the manufacturing process of polymerization or also before heat treatment of the polymer.

Additional additives can be added to polyolefins containing compounds of the general formula I and II to IX, which improve their properties. These are, for example, lubricants such as calcium stearate, light stabilizers of the flame type, antistatic agents, flame retardants, etc. These additives can further improve the properties of polyolefins for their wider and more specific use.

The compounds of general formula I can be prepared from the corresponding alkylphenols and /J,/J'-thiodipropionic acid dichloride by a condensation reaction in the presence of triethylamine (USSR 369 119), by direct synthesis of the reacting acrylic acid esters with hydrogen sulfide (NSR 669 961) or from beta-ochloroproprionate and sodium sulfide (Chem. Ber. 63 2393/1930).

The starting raw materials for the preparation of diphenyl and dialkylphenylthiodipropionates, namely phenol and alkylphenols, are more accessible and more economically advantageous. The effectiveness of the compounds of the general formula I together with the antioxidants of the general formulas II to IX is high and comparable to the dialkylthiodipropionates used in practice to date.

In the following, a general example is presented, which further clarifies the object of the invention without limiting it.

Example 1

0.02 moles of alkylphenol, ml of anhydrous benzene and 0.02 moles of triethylamine are introduced into a 100 ml four-necked flask equipped with a magnetic stirrer, a reflux condenser, a chlorcalcium cap, a thermometer and a dropping funnel. 0.01 moles of p, /T-thiodipropionic acid dichloride in 10 ml of benzene at 15 °C. The reaction mixture is then stirred at room temperature for 2 h. The precipitated triethylamine hydrochloride is filtered off and the benzene solution of the product is concentrated under vacuum. The crude product is crystallized from petroleum ether or purified by chromatography. Analytical data of batches 1 to 6 are given in table no. 1.

Table 1’ k a 1

S-( _CH2 - _CH2 -CO-Aryl) ₂

Substance number Aryl Elementary analysis Heating temperature (°C) Extract («) % S Calc. Found 1 (o)- 9.6 9.47 42 92 2 (h ₃ c) ₂ ch— 7.7 7.42 liquid at 20 °C 76 3 (h ₃ c) ₂ ch—<^O^—ch(oh ₃ ) ₂ ch(ch ₃ ) ₂ 6.04 6.4 47 to 48 52 4 < ch(ch ₃ ) ₂ 6.04 5.84 54 to 55 36 5 ch(ch ₃ ) ₂ 7.7 7.46 liquid at 20 °C 48 6 <ch ₃ ) ₃ c-<IS IT?>— 7.2 7.29 56 to 57 80

Unstabilized polypropylene powder (type HPF and II = 8 g/10 min, was mixed together with the additives on a Brábender plastograph at a temperature of 190 °C, under N^, 5 min. Films with a thickness of 0.5 mm were pressed at a temperature of 260 °C, a pressure of 19.6 MPa for 10 min.

Thermal stability assessment

Example Mixture composition 1.2 IP 170°C (min) Drying room (h) 140 °C A 0.15% AO-49 0.15% fabric w. 1 515 210 B 0.15% AO-49 0.15% substance S. 2 29 306 C 0.15% AO-49 0.15% substance w. 3 18 354 D 0.15% AO-49 0.15% substance no. 4 14 229 E 0.15% AO-49 0.15% substance no. 5 27 104 F 0.15% AO-49 0.15% substance no. 6 42 200 G 0.15% AO-49 without sulfur stabil. 5 20

- substances No. 1 to 6 correspond to the composition given in tab. No. 1 and each mixture contains 0.15%

Calcium stearate.

- AO-49 mixed phenolic antioxidant of general formula III.

Example 2

Polypropylene samples were prepared in the same way as in Example 1

Composition of the mixture

Drying oven 140 °C (h)

0.5% of the substance of general formula II, where R ^{1 2} = octadecyl,

^R2 = ^R3 _{= C4H9852}

0.4% of substance í. 3 0.6% of substance of general formula IV

0.3% substance ?. 3,911

0.4% of the substance of general formula VI

0.5% substance No. 3 903

0.3% of the substance of general formula VII R^ = nonyl

0.6% of substance ?. 3 η = 1 to 3,917

0.85% of the substance of general formula IX R^ = t-C^H^, n = 2

0.05% of substance No. 3 951

- each mixture contains 0.15% calcium stearate

- corresponds to the composition listed in tab. δ. 1

Example 3

A mixture of polyethylene (melting index 2 g/.0 min, Spec. weight 0.920 g/cm^) was prepared on a double cylinder at a cylinder temperature of 120 °C. Homogenization time 10 min. Films with a thickness of 0.5 mm were prepared from the homogenized samples in an electrically heated hydraulic press.

Mixture composition IP 180°C (min) 0.05% AO 49 ¹ ) 0.05% of batch no. 3 63 0.05% Ca Stearate 0.15% Ca Stearate 39

V mixed phenolic antioxidant of general formula III

Claims (2)

FIELD OF THE INVENTION Polyolefins, in particular polyethylene and polypropylene, stabilized against thermal degradation and oxidation, characterized in that they contain from 0.01 to 5% by weight of diphenyl or dialkylphenyl - (R) -thiodipropionate of the formula I II / zyx (R1, n zch2ch2) —C — o — ς Oy (I) ch2ch2 — c (RZ »n Wherein R and R are the same or substantially normal or branched alkyl of 1 to 24 carbon atoms and n = 0 to 4 and 0.01 to 5 percent by weight of one or more antioxidants of formulas II to XX, HIM O / —CH ₂ CH ₂ COO — R ¹ (II) 12 * 3 wherein R, R, R ^J are the same or rflzne normal or branched alkyls having 1 to 18 carbon atoms, HIM - <®x ( ^R4 ) n (III) where R is normal or branched alkyl having 1 to 50 carbon atoms and n = 0 to 4, 2 3 R and R ^J are as defined above (IV) wherein R * is normélny or branched alkyl having 1 to 18 carbon atoms, aralkyl having 7 to 36 carbon atoms, and η = 1-3, (R ¹⁾ n OCH _{2 of} CH ₂ O, (R ⁴ ) n; P-o (IX) OCH CH, O where r 'is normal or branched alkyl of 1 to 18 carbon atoms, aralkyl of 7 to 36 carbon atoms and η = 1 to 3 *