DE1420326A1 - Process for the halogenation of high molecular weight polyolefins - Google Patents

Description

D 27 004 IYd / 39o

The Dow Chemical Company, Midland, Michigan, T. St. A.

Process for the halogenation of high molecular weight polyolefins

From the United States Patent Document 2 18J 556 is a process for the halogenation of ethylene polymers with free halogen in the presence of halogen transfer agents, such as aluminum * or iron chlorides, known "The disadvantage of this process is the very long reaction time, which is necessary to achieve an appropriate halogenating degree Significantly higher halogenation rates are achieved by the process of US Pat. No. 2,50J,252, which describes the chlorination of polyethylene in the presence of aliphatic azo compounds.

According to the invention it has been found that the rate of halogenation versus the method of U.S. Patent No. 2,503,252 further increased and / or higher degrees of halogenation

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achieved

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can be achieved if the halogenation of polyolefins is carried out in the presence of water-soluble hydroporoxide catalysts aqueous suspension a smaller amount of a water-soluble free radical-forming hydroperoxide catalyst of the general formula XYZCOOH, where X, Y and Z are independently alkyl radicals with 1 to 8 carbon atoms, with no more than one of the best X, Y or Z being hydrogen, and that Polyolefin suspended in water is subjected to the action of a halogenating agent in the presence of the catalyst at a ^{temperature between about 80 and 95 ° C.}

According to the invention, polymers can be halogenated which consist of recurring groups -CH ₂ -, -CHE- and CRG groups and mixtures thereof, in which R and G are independently substituted alkyl or aryl groups Polystyrene, polyvinyltoluene and the like. The halogenation of high molecular weight polyethylene, polypropylene, polybutylene and copolymers of these polyolefins is particularly preferred according to the invention. Both essentially linear and branched polymers can be used. In any case, it is particularly advantageous »to halogenate normally solid starting polymers.

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Bas

Das.zu halogenating polyolefin preferably has an average particle size of about 0.03 his can also be used materials having smaller or larger particle size about 1.3 mm diameter although _t. If desired, wetting agents such as sulfonates, sulfates, polyphosphates, polyglycolamine and other surface-active agents can be added to stabilize the aqueous suspension of the finely divided polyolefin during the halogenation. The use of a wetting agent only facilitates the mechanical handling of the suspended polymer, but has no influence on the production of a halogenated product. In many cases it is necessary to use a small amount of hardening agents, especially if a polymer that has not been dried after its preparation is halogenated or if effective stirring is expedient and useful for the preparation and maintenance of the polymer slurry.

The solids content of the suspended reaction mass seems to have little effect on the reaction rate • provided that is maintained during the implementation of the uniformity and homogeneity of the slurry and maintain * Usually has a slurry containing about 2-12 percent. "$ Peststoffe in suspension has been found to be practical and suitable, although the stated range may be

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can also be exceeded or undercut »Under certain circumstances can be suitable variations with particular polymers and different physical embodiments lead to satisfactory results or even be necessary

Examples of water-soluble, radically decomposing catalysts of the formula XYZCOOH ₉ in which X, Y and Z independently of one another denote alkyl radicals with fewer than 8 carbon atoms or hydrogen atoms, with the restriction that no more than one of the best X, Y and Z is hydrogen, are ethylmethylhydroperoxide, * pentamethylethylhydroperoxide, i-methylcyclohexyl-1-hydroperoxide, sec-butyl hydroperoxide and cyelohexyl hydroperoxide. Tert.-butyl hydroperoxide is particularly preferred. In general, the hydroperoxide catalyst, especially tert.-butyl hydroperoxide, is used in an amount between about 0.001 and 1.0% by weight based on the weight of the polyolefin to be treated.

Since the translation speed is usually in relation to the The concentration of the catalyst increases, it is advantageous to use only βo-much catalyst, as for a complete Uasetzung is required within a desired period »Excess amounts of catalyst must, especially near the end the implementation 'to be avoided'. Unused catalyst is often very difficult to remove from the halogenated product. In certain cases it is preferable to use higher catalyst,

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concentrates

to use concentrations than those specified, e.g. if the to analogous to polyolefin has a relatively low reactivity In addition, certain catalyst samples -Show deviations from your expected responsiveness » This may make it necessary to use them in larger or smaller quantities than was to be expected in advance.

According to the invention, any halogen whose atomic number is 18-1, where η is 1 or 2, can be introduced into the polyolefins. The halogenating agents which can be used include free chlorine and bromine and their mixtures. Due to its generally greater availability as well, because he and achievable thereby advantageous properties of polyolefins halogenate it is preferable to work with free chlorine as a halogenating agent to * *

Reaction temperatures between about 80 and 95 ° C are particularly advantageous, while a reaction stone temperature of about 80-95 ° C for the chlorination van. Polyethylene with high molecular weight, whose structure is essentially linear: 1st and which has a melting point of about 125 to · -1-55 ° **, under the influence of tert-butyl hydroperoxide is the most optimal, it can with the special softening temperatures of others Polyolefins to be halogenated and other factors will vary

8 0 9 8 0 3 / Q 6 1 1 speed

speed of the catalyst that you can apply without risk can be halogenated without a sintering or melting de3 To cause polymerizates «Often the optimal conversion temperature is in a range between about 5 ° and 20 ° C below the

Sintering temperature of the polymer to be halogenated » In addition, the reaction temperature is expediently so chosen that enough halogen dissolves in the suspension under the pressure used for the reaction

The optimum reaction temperature can also fluctuate in the course of halogenation due to changes in the softening point of the polymer subjected to halogenation with different contents of halogenated tendencies polymer vary ,, In such cases, it is advantageous ,, au change the Eeakt ions temperature within acceptable limits to aie * the implementation of changing conditions AEEN -during adjust *

The Sälogenierung / implementation according to the invention can be advantageous been carried out at atmospheric pressure, although one. if it is desired, with überatmaaphäri already. Pressing can work, in order to accelerate the implementation speed further · The The ratio of the participants in the reaction is a Procedure is not critical, though, one gets better results

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achieved »

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achieved when the reaction is carried out under atmospheric pressure with excess halogenating agent

The implementation can be carried out batchwise or continuously, whereby the continuous implementation with Bückführung unreacted Reactant can be carried out.

about the superiority of the method according to the invention to ensure the process of US patent specification 2 505 252, the following comparative tests were carried out.

Tert «-Butyl hydroperoxide was with <p £, 0C-Azobis - (<iC, #" - dimethylvaleric acid nitrile) as a chlorination catalyst in the chlorination of high molecular weight polyolefins in aqueous suspension -compared · Two comparative tests were carried out * one under normal pressure, the other under overpressure «

Comparative experiment At '

In a glass jar were in the absence of actinic radiation 3200 parts of water and 10O parts of a solid, linear Ethylene homopolymer (l_ äMQ) given that one is sufficient had a small particle size of a maximum of 0.42 mm. 15 drops an etching agent (sodium dodecyl sulfate) were added, to achieve a better bis-dispersion · * Bas mixture was stirred and the air by purging with nitrogen for 5 minutes

removed · - 15 g of chlorine were then duroh the reaction mixture

•. BATHROOM LOCAL GINAL

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directed us to push the nitrogen. Then the catalyst used in each case in a lienge yon $ 0.1 was based on the polyethylene, is added and allowed to disperse thoroughly; and the chlorination was carried out in such a way that chlorine was passed through the well-stirred suspension at a rate of about 0.5 g per minute until a further 35 ß had been passed through Water, washed and dried «In the two experiments in which the two different catalysts were used, the yield was practically quantitative.

Chlorine addition- chlorination- final chlorine content

catalyst Time Min » temperature of the product tert-butylhydrο-
peroryd 68 Min. 80 ° C 13.7 pounds (c *, <T-diine thyl-
valeric acid
nitrile) 70 77 ° C .8.3 #

Comparison experiment Bi

This comparison test was carried out under the same conditions (vessel loading, reaction conditions, etc.) as in the comparison before Book L , but the chlorination was carried out under an overpressure of 0.7 atm. The gaseous chlorine was

into the slurry at a sufficient rate

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introduced to the overpressure of 0.7 atu. aufrachtz-uerlialtan.
After the 35 g of chlorine had been passed in, the mixture was allowed to react a further part, after which the remaining excess chlorine pressure was released. The product was worked up as in the comparison experiment A * You yield
was practically quantitative in the two experiments carried out with the two different catalysts
The results obtained are summarized in the following table.

Chlorine addition - chlorination? - post-reaction - final chlorine content
Catalyst time temperature tiohszeit of the product

tert-butyl hydro
peroxide 34 min. ßO ° C. 8th Min. H , 7 # o £ _t oL -Azobis-
(^, Γ-dimethyl-
valeric acid
nitrile) 89 min. 77 ° C. 40 Min. 13th

If halogenation of the polyolefinic material has taken place up to to the extent desired, it can be filtered from the suspension in the inert suspended liquid, washed and dried, to prepare it for further use.

In the following example, if not stated otherwise, all Partial quantities and proportions are based on weight.

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Example 809803/0611

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example

To begin with the results of a non-catalyzed implementation To show were about 112 g of a finely divided macromolecular Type of polyethylene with 1.480 liters of water and about 0.4 g a polyglycolamine curing agent slurried in a 3- "I <iter-Xorbent, which is equipped with an effective paddle stirrer. The predominant particle size of the polyethylene was below about 44/1 sas molecular weight determined by melt viscometry

* ο

was about 115 * 000, the melting point approximately 130 C. Bio introduced Ingredients were until a similar Mixed dispersion

The prepared 7% slurry was heated to around 80 ° C heated and flushed with nitrogen. Chlorine gas was then added through an open-topped filler neck which was inserted into the slurry immersed while the reaction temperature was kept constant at about 80 ° C. The chlorine was at constant speed of about 100 g per hour while maintaining the stirrer speed of about 350 ΰ / min. introduced. The reaction ended after about 4 hours. The reaction geraisoh was cooled and before filtering with Purged with nitrogen. -You got a product with a lot of combined chlorine of only about $ 23.4 »corresponding to about 0.24

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Equivalent text

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Equivalents of chlorine per equivalent of ethylene in the polymer (O _t 24 eq. * Gl / eq, .PÄ). Based on the entire period of use "the chlorination rate was only about 0.06 equivalents of chlorine per equivalent of ethylene in the polymer per hour of chlorination (0.06 eq.Cl / eq.PÄ / hour).

The above procedure was repeated with the exception that "at the beginning of the chlorination, 0.070 g of an aqueous 67% solution of tert-butyl hydroperoxide and then the same amount of catalyst were introduced every 5 hours. At the end of a four-hour catalyzed reaction, a chlorinated reaction resulted poly- 'ethylene having a content of about 39 i # 8 ° to gebundenon chlorine. This corresponded to 0.53 Äq.Gl / Äq.PÄ and a chlorination rate of 0.132 achieved ÄqoCl / Äq.PÄ / STDI by applying d63 Bydroperoxyd catalyst was consequently an increase of the implementation speed by about 120 fo

Table I, which reveals the influence of tert-butyl hydroperozide as a catalyst for the chlorination of polyethylene in a water suspension, shows the results of various other chlorinations carried out in the same way referred to as Yersu- ¹ before 12 and -13. The tests: 1, 3, 6 _t Q and 12 in Table I refer to s, i <? B; on. non-catalyzed chlorinations and are only used for comparison purposes. In Tables II and III

..-., ..- ^, -: BADORiGlNAL

are

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Certain Kennzeiohon the Ausgangspolyäthylene _t were ohloriert indicated. Thus, Table II contains the starting molecular weights, the relative degrees of crystallinity and the surface areas of the polyethylene used in the experiments in Table I. The sieve analyzes of the initial polyethylene samples which were chlorinated can be seen from Table II.

Tabel!

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• Table I

Tert <, - butyl hydroperoxide as a catalyst for the halogenation of polyethylene

Test polyethylene-Kr, sample (g)

1 (f) "A" 2 "A ^M 3 (f) •• A " OO 4th "A" O "A" co 6 (f) "A" po 7th ^W A " O 8 (f) "B" CO 9 «Β" O 10 "C" cn 11 fiQti - » 12 (f) ItJ) H 13th «351 14th "D" 15th "E" 16 »A ¹¹ 17th 18th M]) M

η η ferap. catalyst fo Cl after - speed M. ⁰ C concentration, 4 hour (s) lci.Cl/Eq.Pä/hr. Stir M. 80 Gew.-fu, "related. 51.6 Äq.Cl / Äci.PÄ 4 hours average RPM Il •1 on Pl (d) 53.5 after 4 hours '0.090 510 Il H 0.00 26.2 0.36 0.22 Il It w 0.189 45.8 0.88 0.070 350 Il N 0.00 47.0 0.28 0.16 M. •1 70 0.189 29, e 0.64 0.170 J » Il Il V 0.047 40.6 0.680 ' 0.083 It H 75 0.00 11.5 0.333 0.133 ti 80 0.189 35.0 0.53 0.025 Il 0.00 25.4 0.10 0.105 - π 0.189 44.6 0.421 0.068 Il 0.00 23.4 0.272 0.155 Il 0.139 40.6 0.621 0.06 Il 0.00 35.0 0.24 0.132 Il 0.047 44.6 0.53 0.105 η 0.0187 35.6 0.421 0.154 ti 0.047 52.2 0.618 0.107 η 0.37 (a) 40.6 0.429 0.093 0.047 (b) 0.37 0.131 0.047 (c) 0.525

Catalyst concentration is added after one hour of chlorination. No 'catalyst during the rest of the implementation.
Catalyst concentration was added every 2 hours. Catalyst concentration was added every 0.5 hours. Calculated as 100 ^ hydroperoxide.

Controlled by titration of HCl released in the reaction. All figures were confirmed by Parr-Boaben analysis.
Not according to the method according to the invention.
Cf. Table II and UI.

VX
I.

cc iv:

CT

Act II

Physical © properties. and characteristics of the initial polyethyleno, those using tert-butyl hydropexoxide were chlorinated »

Polyethylene
sample Middle
Molecular weight
from PÄ Percentage
Criminality
from Pl (h) Surface of A. 60,000 57.7 4.81 B. 49,000 52.8 5.68 C. 60,000 57.0 5.79 S. 115 000 42.5 1.55 E. 25,000 58.5 2.77

(h) Relative and approximate values, by X-ray examinations bestiEiat on the powdery polyamide.

2
(j) Measured in m per g using the nitrogen absorption method.

table III

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labile III

Sieve analyzes of the starting polyethylenes

Samples Kο. t A. B. C. P. E. held back by
clear mesh size
in / i Wt .- ^ 500 <k> 'W 9.0 41.6 1.1 550 W. (k). 3.6 15.9 2.6 250 1.0 1.2 2.9 10.9 4.7 177 0.6 0.5 2.8 9.5 20.4 149 15.6 7.4 1.9 4.9 18.5 105 11.9 17.8 9.5 7.9 17.4 74 21.2 41.4 18.8 6.0 8.6 62 9.5 17.4 (k) (k) (*). 53 12.1 11.3 22.5 5.0 4.1 44 22.3 2.1. 19.0 1.4 9.8 Backlog (smaller
than 44 / a) 6.0 '03 10.0 1.0 12.1

'(ic) Not determined

illustration 1

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Figure 1 (abzisset tart.-BuOOH, weight-5 &, based on polyethylene »ordinate j chlorination rate» £ q, .Cl / eq.PE / hour.) Shows the influence of the catalyst concentration on the chlorination rate of polyethylene with tert-butyl hydroperoxide again. Curve ¹¹ A "corresponds to the results of experiments 1-7 and 16 in Table I" Curve ⁿ B ⁿ those of experiments 12, 13 "14, 17 and 18" From the curves it can be seen that a concentration of constant about 0 , 05 f ^a of tert-BuOOH in the reaction mass during the chlorination of polyethylene leads to optimal results. which were achieved with and without the use of a catalyst. Curve ^M C ^rt (0 i » tert-BuOOH) is typical for non-catalyzed conversions. Curve" D "(0.019 $ tert-BuOOH) gives the distinct advantage and benefit when used of only small amounts of tert-BuOOH again. Curve "E" (0.047 # tert-BuOOH), in the course of which two maxima usually occur, shows the standard dissolution rates that can be achieved if optimal amounts of tert-BuOOH catalyst are used .

Pitentaa prflones

SAD ORi

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Claims (1)

Claims, 1. Process »for the halogenation of a high molecular weight polyolefin, characterized in that one uses an aqueous suspension of the polyolefin in the form of fine particles, the aqueous suspension a smaller amount of a water-soluble, Hydroperoxide catalyst which forms free radicals general formula XYZCOOH added, wherein X, Y and Z independently from each other alkyl radicals with 1 to 8 carbon atoms or hydrogen atoms can be, with no more than one of the best X, Y and Z is hydrogen, and the polyolefin suspended in water in the presence of the catalyst at between about 80 and 95 ° C! Temperature of the action of a halogenating agent a subject * 2, method according to claim 1, characterized in »that as Halogenating agent free chlorine is used, 5 * The method according to claim 1 or 2, characterized in that a polyethylene, with an average particle size between about 1280 yes and 57 / * is rerweadet. Method Bach to one of the preceding claims, characterized in that the aqueous suspension contains approximately 2 and 12 volumes of suspended solids, _ßAD QRiGiNAL 809803/06 11 5 · Method according to one of the preceding claims, characterized characterized in that introduced about 0.05 wt .- ^ of catalyst and maintained in the suspension during the chlorination process «ground · D 688 / Dr «Pa.-zu BATH 8 0 98 03/06 11