阅读说明：本技术 至少一种半过氧缩醛单独地或与其它过氧化物组合用于促进在高压下的乙烯的聚合或共聚的用途 (Use of at least one hemiperoxy acetal, alone or in combination with other peroxides, for promoting the polymerization or copolymerization of ethylene at high pressure ) 是由 B.范赫梅尔里克 V.梅嫩托 于 2019-12-18 设计创作，主要内容包括：本发明涉及选自半过氧缩醛的至少一种过氧化物单独地或与一种或多种不同的另外的过氧化物组合用于在高压下的乙烯的自由基聚合或共聚的用途。本发明还涉及制备聚乙烯的方法,该方法包括以下步骤：在单独的或与一种或多种不同的另外的过氧化物组合的选自半过氧缩醛的至少一种过氧化物的存在下,在高压下的乙烯的自由基聚合或共聚。本发明还涉及一种组合物,其包含乙烯、选自半过氧缩醛的至少一种过氧化物、以及任选的不同于半过氧缩醛的一种或多种另外的过氧化物。(The present invention relates to the use of at least one peroxide selected from the group of hemiperoxy acetals, alone or in combination with one or more different additional peroxides, for the radical polymerization or copolymerization of ethylene under high pressure. The invention also relates to a process for preparing polyethylene, comprising the steps of: free-radical polymerization or copolymerization of ethylene under high pressure in the presence of at least one peroxide selected from the group of hemiperoxy acetals, alone or in combination with one or more different additional peroxides. The invention also relates to a composition comprising ethylene, at least one peroxide selected from the group of hemiperoxy acetals, and optionally one or more additional peroxides different from the hemiperoxy acetal.)

1. Use of at least one organic peroxide selected from the group of hemiperoxy acetals, alone or in combination with one or more different additional organic peroxides, for the radical polymerization or copolymerization of ethylene under high pressure.

2. Use according to claim 1, characterized in that the peroxide is chosen from hemiperoxy acetals having a half-life temperature of one minute at atmospheric pressure of from 125 ℃ to 160 ℃, preferably from 130 ℃ to 155 ℃, more preferably from 140 ℃ to 150 ℃.

3. Use according to any one of the preceding claims, characterized in that the peroxide is chosen from the hemiperoxy acetals corresponding to the following general formula (I):

in the formula (I):

r1 represents a linear or branched C1-C4, preferably C1, alkyl group,

r2 represents a branched C4-C12, preferably C5, alkyl group,

-n represents zero or an integer from 1 to 3,

-R3 represents a linear or branched C1-C3 alkyl group.

4. Use according to any one of the preceding claims, characterized in that the peroxide(s) are chosen from 1-methoxy-1-tert-amylperoxy cyclohexane (TAPMC), 1-methoxy-1-tert-butylperoxycyclohexane (TBPMC), 1-methoxy-1-tert-amylperoxy-3, 3, 5-trimethylcyclohexane, 1-methoxy-1-tert-butylperoxy-3, 3, 5-trimethylcyclohexane, 1-ethoxy-1-tert-amylperoxy cyclohexane, 1-ethoxy-1-tert-butylperoxycyclohexane, 1-ethoxy-1-tert-butyl-3, 3, 5-peroxy cyclohexane, and mixtures thereof.

5. Use according to any one of the preceding claims, characterized in that the peroxide is 1-methoxy-1-tert-amylperoxy cyclohexane.

6. Use according to any one of the preceding claims, characterized in that the further peroxide(s) are chosen from peroxyacetals, preferably those having a one minute half-life temperature at atmospheric pressure of from 145 ℃ to 180 ℃, preferably from 150 ℃ to 180 ℃, more preferably from 160 ℃ to 175 ℃, still more preferably from 160 ℃ to 170 ℃.

7. Use according to any one of the preceding claims, characterized in that the additional peroxide(s) are chosen from peroxyacetals capable of initiating the radical polymerization or copolymerization of ethylene at high pressure in the temperature range from 190 ℃ to 250 ℃.

8. Use according to any one of the preceding claims, characterized in that the further peroxide(s) are chosen from peroxyacetals conforming to the following general formula (II):

in the formula (II), R₄To R₁₁Are identical or different and represent linear or branched C₁-C₆Alkyl group of (1).

9. Use according to any one of the preceding claims, characterized in that the further peroxide(s) are selected from 2, 2-di (tert-amylperoxy) propane, 2-di (tert-amylperoxy) butane and mixtures thereof, preferably 2, 2-di (tert-amylperoxy) butane.

10. Use as claimed in any one of the preceding claims, characterized in that said further peroxide(s) can also be chosen from peroxides having a half-life temperature in one minute at atmospheric pressure lower than the half-life temperature of the hemiperoxy acetal as defined in any one of claims 1 to 5.

11. Use according to claim 10, characterized in that the additional peroxide or peroxides are selected from the group consisting of tert-amyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, diethylhexyl peroxydicarbonate, tert-amyl peroxypivalate, tert-butyl peroxypivalate, bis (3,5, 5-trimethylhexanoyl) peroxide, 2, 5-dimethyl-2, 5-bis (2-ethylhexanoylperoxy) hexane, tert-amyl peroxy-2-ethylhexanoate, and mixtures thereof.

12. Use as claimed in any one of the preceding claims, characterized in that said further peroxide(s) can also be chosen from peroxides having a half-life temperature in one minute at atmospheric pressure higher than the half-life temperature of the hemiperoxy acetal as defined in any one of claims 1 to 5.

13. Use according to claim 12, characterized in that the additional peroxide or peroxides are selected from the group consisting of tert-amyl peroxy-3, 5, 5-trimethylhexanoate, tert-butyl peracetate, 2-di (tert-amylperoxy) butane, 2-di (tert-butylperoxy) butane, tert-amyl peroxybenzoate, tert-butyl peroxybenzoate, and mixtures thereof.

14. Use according to any one of the preceding claims, characterized in that the additional peroxide(s) can also be chosen from peroxy esters capable of initiating a radical polymerization or copolymerization of ethylene at high pressure at a temperature of from 160 ℃ to 190 ℃, preferably from tert-butyl peroxy-2-ethylhexanoate, tert-amyl peroxy-2-ethylhexanoate and mixtures thereof, more preferably tert-butyl peroxy-2-ethylhexanoate.

15. Use according to any one of the preceding claims, characterized in that the additional peroxide(s) can also be chosen from peroxyesters capable of initiating the radical polymerization or copolymerization of ethylene at high pressure at temperatures higher than 220 ℃, preferably from di-tert-amyl peroxide, 2, 5-dimethyl-2, 5-di (tert-butylperoxy) hexane, di-tert-butyl peroxide, 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane, or 3,3,5,7,7-15 pentamethyl-1, 2, 4-trioxepane, and mixtures thereof.

16. Use as claimed in any one of the preceding claims for the free-radical polymerization of ethylene under high pressure.

17. A process for preparing polyethylene or ethylene copolymers, said process comprising the steps of: free-radical polymerization or copolymerization of ethylene under high pressure in the presence of at least one peroxide as defined in any one of claims 1 to 5, alone or in combination with one or more different further peroxides as defined in any one of claims 1 and 6 to 16.

18. A process as claimed in claim 17, characterized in that the polymerization or copolymerization step is carried out by: injecting a peroxide as defined in any one of claims 1 to 6 alone or in combination with one or more different further peroxides as defined in any one of claims 1 and 6 to 16 at one or more points of the reactor.

19. A process as claimed in claim 17 or 18, characterized in that the ethylene copolymer is chosen from copolymers of ethylene and of acrylic esters, copolymers based on ethylene and of at least one α -or α, ω -olefin, copolymers based on ethylene and of carbon monoxide and copolymers based on ethylene and of comonomers of unsaturated cyclic anhydrides.

20. A process as claimed in claim 17 or 18, characterized in that the polymer to be prepared is polyethylene, preferably low-density polyethylene.

21. A composition comprising:

(i) at least one ethylene monomer,

(ii) at least one peroxide chosen from the hemiperoxy acetals as defined in any one of claims 1 to 5, and

(iii) optionally, at least one additional peroxide different from peroxide (ii) as defined in any one of claims 1 and 6 to 16.

Examples

Example 1

Organic peroxides tested

In the following examples, tert-butyl peroxy-2-ethylhexanoate (A) is used26) (referred to as reference peroxide) and on the other hand with 1-methoxy-1-tert-amylperoxy cyclohexane TAPMC (referred to as peroxide (1)), the free-radical polymerization of ethylene under high pressure is carried out.

The peroxide (1) and the reference peroxide are two organic peroxides capable of initiating the radical reaction of ethylene at high pressure in the temperature range of 160 ℃ to 190 ℃ (referred to as the medium temperature range).

In this comparative example, the reference peroxide was replaced by an equal weight (weight for weight) of peroxide (1).

The reference peroxide has a self-accelerating exothermic decomposition temperature (SADT) of 35 ℃, which means that it must be stored in a cold environment at temperatures around 5-10 ℃ and special precautions must be taken when transporting it.

As such, the peroxide (1) has a self-accelerating exothermic deposition temperature (SADT) of 60 ℃, allowing it to be stored and transported at ambient temperature.

Experimental protocol

In a 435ml high-pressure stirred batch reactor of autoclave type, ethylene was injected until a pressure of 1800 bar, i.e. approximately 207g, was reached. The stirring was 1000rpm (revolutions per minute). The initial temperature was established as a reactor wall temperature of 160 ℃ by means of heating rods placed in the reactor wall.

The peroxides (peroxide (1) and reference peroxide) were diluted separately in heptane and then injected into the reactor.

The transfer agent propionaldehyde was also used to limit molecular mass and reactor fouling.

Thus, upstream of the reactor and at low temperature, each organic peroxide (1) and the reference peroxide) was diluted in heptane and propionaldehyde so as not to initiate the reaction before entering the reactor. Each mixture was then injected into the reactor using a high pressure pump. Polymerization was triggered once the peroxide was injected at an initial temperature of 160 ℃.

During the free radical polymerization reaction, the thermal evolution curve of the exotherm after introduction of each peroxide into the reactor and corresponding to the polymerization of ethylene was determined. The exotherm corresponds to the kinetics of the radical reaction.

The exotherm curve passes through a maximum temperature, which is referred to as the maximum temperature achieved and is recorded as Tmax.

For a given level of addition, Tmax is determined and the rate at which it is obtained.

The reaction is continued until the final temperature returns to the value of the same level as the initial temperature.

The reactor was then depressurized and the resin was recovered to measure the specific peroxide consumption.

Results

Maximum temperature attainment

Under the operating conditions described above (initial temperature 160 ℃ and pressure 1800 bar), for both peroxides (reference peroxide tert-butyl peroxy-2-ethylhexanoate), (b)26) And 1-methoxy-1-tert-amylperoxycyclohexane (TAPMC) peroxide) and the Tmax values observed for the respective concentrations in relative weight, in ppm by weight with respect to the ethylene monomer, of 46 and 45ppm, respectively, are obtained in the following times: 8.3s and 11.7 s.

These Tmax values are obtained from almost (virtually) superimposed kinetic curves, and the slightly slower obtainment of Tmax with a TAPMC according to the invention is due to the fact that: the Tmax obtained with this peroxide is higher: 243 ℃, in contrast, for reference 214 ℃, although the addition level by weight was almost the same.

Specific consumption of

The specific consumption of peroxide (1) and reference peroxide was also measured for both radical polymerizations, using the same addition level and enabling maximum temperatures Tmax of the peroxide, respectively, to be obtained, namely 230 ℃ and 205 ℃, while the initial temperature was still 160 ℃.

[ Table 1]

According to this example, it was found that when a single initiator is used, in the case of a commercial peroxide (i.e. undiluted peroxide), peroxide (1) (TAPMC) is used, relative to the reference peroxide(s) ((r))26) (which is generally considered to be preferred in the prior art), the production of LDPE allows a gain in specific consumption of about 70%.

Example 2

Organic peroxides tested

In the following examples, the free-radical polymerization of ethylene under high pressure was carried out with two organic peroxide blends containing, respectively: a mid-range operating temperature peroxide (1) from example 1 or reference peroxide) in combination with a more reactive organic peroxide as described above and another less reactive organic peroxide.

Thus, two free-radical polymerizations of ethylene at high pressure were carried out with the following peroxide initiator systems:

-ternary blend 1: tert-butyl peroxypivalate (C)11) (as a peroxide of higher reactivity than the reference peroxide), the reference peroxide (tert-butyl peroxy-2-ethylhexanoate-26) And tert-butyl peroxy-3, 5, 5-trimethylhexanoate(s) ((R))270) (as a less reactive peroxide than the reference peroxide),

-ternary blend 2: tert-butyl peroxypivalate (C)11) (as a peroxide more reactive than the reference peroxide (1)), peroxide (1) (1-methoxy-1-t-amylperoxy cyclohexane-TAPMC) and t-butyl peroxy-3, 5, 5-trimethylhexanoate: (270) (as a less reactive peroxide than the reference peroxide).

In ternary blend 2, the reference peroxide was replaced by equal amounts by weight of peroxide (1).

For each of these two ternary blends, the mass ratio of the three peroxides (Lup11/Lup26/Lup270 and Lup11/TAPMC/Lup270) in terms of their commercial display was in each case 2:1: 1.

Only have11 was used for safety reasons in a diluted commercial form in 75% of the repressor (phlegmatizer) isododecane, presented as a commercial display of Luperox 11M75(Lup11M75), other peroxides being available in undiluted form. Thus, the mass ratio of the Lup11/Lup26/Lup270 system indicates a weight ratio between the undiluted peroxide actives of 1.5/1/1, respectively, which corresponds to a 2:1:1 by weight mixture of Lup11M75/Lup26/Lup 270.

Ternary blend 1 is referred to as the reference blend.

Experimental protocol

Two radical polymerizations were carried out in the same batch reactor as in example 1.

However, with the aid of the ternary blend, the initial temperature of the ethylene feed at 1800 bar was established at a lower initial temperature of 145 ℃, with the most reactive organic peroxide determining operation at a lower initial temperature than in example 1.

The tertiary reference blend containing TBO and blend 2 containing peroxide (1) were tested at the same total addition level for organic peroxide in the first stage as in example 1 to judge kinetics (check reaction exotherm ramp slope and Tmax obtained as a function of time).

Results

Maximum temperature attainment

As in example 1, the kinetic curves show very similar heat release slopes, Tmax being obtained in 12.3 seconds for the ternary reference blend, but for the replacement with TAPMCTernary blend 2 of 26 (replaced by equal weight) gave a Tmax in 14.2 seconds.

Again, the difference in the time to obtain Tmax is due to the fact that: tmax was 256 ℃ for peroxide (1) and 249 ℃ for the ternary reference blend, although the total addition level of peroxide, expressed in pure form, was 91ppm by weight and 113ppm by weight for the ternary reference.

Specific consumption of

The specific consumption of the total amount of peroxide involved in the two ternary blends was also measured at two maximum temperatures Tmax (i.e. 250 ℃ and 240 ℃) at an initial temperature of 145 ℃ for each blend.

[ Table 2]

According to this example, it was found that when the ternary blend is of a type comprising peroxide (1) (which according to the invention replaces peroxide (1))26) A mixture of a more reactive peroxide and a less reactive peroxide and although peroxide (1) is present in the blend at less than 30 mass%, peroxide (1) (TAPMC) is used in respect of pure peroxide (i.e. undiluted peroxide), relative to the composition of peroxide (1) when used in the blend26 (which are generally considered preferred by those skilled in the art), the production of LDPE benefits from a gain in overall specific consumption of around 30%.

Example 3

In the following examples, the free-radical polymerization of ethylene under high pressure was carried out with two organic peroxide blends containing, respectively: a mid-range operating temperature peroxide (1) from example 1 or reference peroxide) in combination with a more reactive organic peroxide and another less reactive organic peroxide as described above.

Thus, two free-radical polymerizations of ethylene at high pressure were carried out with the following peroxide initiator systems:

-ternary blend 3: tert-butyl peroxypivalate (C)11) (as a peroxide of higher reactivity than the reference peroxide), the reference peroxide (tert-butyl peroxy-2-ethylhexanoate-26) And tert-butyl peroxy-3, 5, 5-trimethylhexanoate(s) ((R))270) (as a less reactive peroxide than the reference peroxide),

-ternary blend 4: tert-butyl peroxypivalate (C)11) Peroxide (1) (1-methoxy-1-tert-amylperoxy cyclohexane-TAPMC) and 2, 2-di (tert-amylperoxy) butane (peroxide (2) belonging to formula (II) -520) (as a peroxide less reactive than peroxide (1)).

In two ternary blends, reference peroxide: (26) Equal weight substitution with peroxide (1) and tert-butyl peroxy-3, 5, 5-trimethylhexanoate: (a)270) 2, 2-di (tert-amylperoxy) butane belonging to the above-mentioned formula (II), known as peroxide (2), etc.

For each of the two blends, three peroxides: (a), (b), (c), (d11/26/270 and11/TAPMC/520) the mass ratio in its commercial form was 2:1: 1.

11 for safety reasons in the repressor isododecane 75%, appear asA diluted commercial form of the commercial display of 11M75 was used.

520 for safety reasons in the form of a 50% dilution in the repressor isododecane: (520M 50).

The mass ratio of the pure peroxide in ternary blend 3 was 1.5/1/1 in the above order, and the mass ratio of the pure peroxide in ternary blend 4 was 1.5/1/0.5.

Ternary blend 3 corresponds to a conventional peroxide initiator system based on peroxyesters and corresponds hereinafter to the reference blend.

Experimental protocol

Both free-radical polymerizations were carried out in the same batch reactor as example 2 and under the same conditions, which means that the initial temperature of the ethylene feed at 1800 bar was established at an initial temperature of 145 ℃.

The exotherm curve of the radical reaction, the maximum temperature obtained and the specific consumption of peroxide were determined for each polymerization reaction, as in example 1. Thus, the properties of the polymerization of ethylene were compared for each ternary blend.

Results

The kinetic curves determined for each blend showed very similar heat release slopes, giving a Tmax in 12.3 seconds for the ternary reference blend (ternary blend 3) and in 11.7 seconds for ternary blend 4.

However, the maximum temperature (Tmax) obtained with blend 4 was 256 ℃ and 249 ℃ for the reference blend, although the total amount of peroxide participating in the radical polymerization was much lower for ternary blend 4 (48 ppm expressed as pure peroxide) relative to 113ppm for ternary blend 3.

This difference shows that the yield of resin (polymer) is higher with a smaller total amount of peroxide involved in the case of using blend 4 according to the invention.

Example 4

In this example, the experiment described in example 3 was repeated several times by varying the total concentration of peroxide, still in the above ratio (weight ratio of commercial organic peroxide 2/1/1), while maintaining the same initial conditions (initial temperature 145 ℃ and pressure 1800 bar) and using the reference blend (ternary blend 3) and blend 4.

Results

In all cases, the maximum temperature Tmax was greater when the total concentration of peroxide in the tested blends was increased. However, ternary blend 4 comprising the peroxide (1)/peroxide (2) pair gave a higher Tmax and therefore a higher polymer yield relative to reference blend 3. When the same total amount by weight of peroxide was used, the difference observed was about 20 ℃ over the range of total peroxide concentrations of 20 to 130ppm by weight expressed as their commercial formulation.

The total specific consumption of ternary blend 4 was at least 35% lower than the total specific consumption of ternary blend 3 for the same total concentration of the peroxide involved.

Example 5

The specific consumption of the total amount of peroxide involved in the two ternary blends described in example 3 was also measured at two maximum temperatures Tmax, i.e. 240 ℃ and 250 ℃, at an initial temperature of 145 ℃.

The total amount of peroxide in the table below is expressed in ppm by weight of peroxide in its commercial dilution (for11 in isododecane 75%, designated Lup11M 75; for the520 in isododecane, 50%, then called520M50；270 and26 are not diluted and therefore their contribution in the ternary mixture is taken to be 100%).

[ Table 3]

[ Table 4]

According to this example, it was found that the ternary blends according to the invention exhibit better radical initiation properties, not only in terms of a reduction of the specific consumption of about 50%, but also in terms of the conversion rate, for the same maximum temperature Tmax obtained in a given zone of the reactor. In fact, the commercial amount of peroxide that can achieve the highest temperature is reduced by at least 45% by the ternary blend according to the invention.