DE2130273C3 - Process for the production of foils and insulated wire - Google Patents

Description

The invention relates to a method for producing insulated D'aht using a hardenable one Polymer mixture which, in particular, can be hardened more quickly than when using the previously known ones Curing methods with known polymer mixtures was possible.

For curing polymers in general, methods using electron irradiation have hitherto been used and other methods by heating a mixture of the polymer with organic peroxide known under pressure. Products obtained by such methods are good because of their good quality Heat resistance and electrical properties in wide range as electrical insulation materials usable.

From FR-PS 13 50928 a method for the production of polyethylene tubing is known, according to which a polyethylene compound is cured by adding a radical generator.

In addition to azonitriles, peroxides are proposed as a subgroup of such radical formers, with practically all existing peroxides are considered equivalent and listed. In the In the examples, no peroxide mixtures and mixtures of other radical formers are used at all. This FR-PS also gives no indication that the use of peroxide mixtures could offer particular advantages, and it is even less clear which combination of the 16 peroxides listed in which weight ratio would have to be used. Rather, it is pointed out in particular to use individual peroxide formers, namely dicumyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) -hexane and 2,5-dimethyl-2,5-di- (tert-butylperoxy) -hexyne-3.

For the chemical hardening of polyolefins are described in US-PS 30 79 370 and 28 88 424 processes, wherein the curing agent is a compound of the formula R - O - O - R '. where R and R 'each a hydrocarbon group with a tertiary one forming the connection to the peroxide oxygen Mean carbon atoms is used.

In particular, di-u-cum-peroxide, 2,5 - dimethyl - 2 ', 5' -di - {tert. - butylperoxy) hexane and 2,5-dimethyl-2 ', 5'-di- (tert-butylperoxy) -hexyne-3 are used. However, if from extruded Mixtures of such peroxides with polyolefins shaped bodies need to be hardened a longer period of time for complete curing because these mixtures have a have longer half-lives.

However, it is advantageous to the speed of production Increase zi by shortening the curing time.

A mixture of polyolefins can effectively be used to shorten the curing time which contains a peroxide with a shorter half-life at higher temperatures of 160 to 200 ° C Although such a peroxide at the curing temperature, i.e. H. 160 to 200 "C, is effective, can leg! Mixing and extruding difficulties arise because of the mixing or extrusion temperature from 80 to 150C premature curing of the polyolefin; can use.

It has been found that the disadvantages described above are overcome by means of polyolefin mixtures which contain peroxide mixtures, which irr at the mixing and extrusion temperatures In the range from 80 to 150 C approximately the same half-lives like known peroxides, have a curing temperature in the range from 160 to 200 ° C however, show a shorter half-life. It is obvious that a polyolefin mixture that contains such a peroxide mixture, while the mixing and extruding are approximately the same like one with a content of known peroxides, but that its hardening is much faster! can be achieved than with known polyolefin mixtures.

The subject of the invention is thus a process for the production of foils and insulated wire which is characterized in that a mixture of at least one dialkyl peroxide and at least: a peroxyester in a weight ratio of 6: 4 to 7: 2 in an amount of 0.1 to 10 parts by weight of the sum of the two peroxides with 100 parts by weight of a polyolefin or copolymer with a predominant olefin content or a mixture such as: Polymers at 80 to 150 ° C, optionally extruded onto an electrical conductor and the coated tete conductor afterwards at a temperature of 150 bi; 300 C is cured.

According to the invention, polymer mixtures are used, the polyolefin or a mainly au; An olefinic copolymer or a mixture of such polymers and a peroxide mixture of ^{at least 1} ns a dialkyl peroxide and at least one 1-eroxyester, the dialkyl peroxide at least one unit of the formula

C C

I!

—C-0—0 — c-c

C C

and the peroxyester has at least one unit

formula

C O

I ü ι

c — c— ο — ο — c — c

i i

IH)

exhibit.

Diacyl peroxides of the formula I are the monoperoxides Di-n-cumyl-, terl.-butyl-u-cumyk teri.-butyl - triphenyl - methyl-, ρ, ρ '- dichloro - dicumyl-, p.p' - Diniiro - dicumyl-, ρ, ρ '- dimethyl - dicumyl-. p.p'-dimethoxy-dicumyl-peroxide or others below Peroxides: 2,5-dimethyl-2 ', 5'-di- (tert-butylperoxy) -hexane, 2,5-dimethyl-2', 5'-di- (tert-butylperoxy) -hexyne-3. 2,2'-di- (tert-butyl-peroxy) -butane, 1,3-di- (tert-butyl-peroxy-isopropyl) -benzoI.

Peroxy esters of the formula II are the monoperoxy esters tert-butyl-peroxy-benzoal, -butyral, -acetate, stearate, octanoate, decanoate or DHteri.-butylperoxy) adipate, 2,5-dimethylhexyl-2'.5'-di-peroxybenzoate.

The mixing ratio of the components of the peroxide mixture can be adjusted according to the deformation and curing conditions of the polyolefin mixture according to the invention can be set.

When the polymer is polyethylene, an ethylene vinyl acetate or ethylene ethyl acrylate copolymer. will according to the invention 0.5 to 5.0 parts by weight of dialkyl peroxide and 0.1 to 5 parts by weight of peroxyester per 100 parts by weight of the polymer used. When mixed with an elastomeric polymer, pro According to the invention, 100 parts by weight of polymer are used per 0.1 to 10 parts by weight of dialkyl peroxide and peroxyester.

The peroxide mixture can be mixed with the polymer in any way, for example directly on a two roll elastomer mixer. Other mixing devices, for example a Banbury mixer can be used.

The polymer mixture according to the invention can, depending on the polymer and peroxide mixture used can be produced in a wide temperature range, and mixing generally takes place with heating to, for example, 80 to 150 C.

Since the peroxide mixture has a significantly longer half-life in the mixing temperature range mentioned the upper limit of the mixing time at this temperature can be extended to some extent without substantial Portions of the peroxide mixture are destroyed. There can thus be a uniform mixing of the polymer can be achieved with the peroxide mixture, the dialkyl peroxide and the peroxyester independently and can be worked into the polymer separately from one another.

The polymer mixture according to the invention can be injection molded. Extrusion or rolling according to known methods Methods are deformed.

The deformation temperature can vary widely depending on the specific peroxide mixture used. or if it is intended. perform the deformation and hardening in a single operation. The molding of the polymer mixture according to the invention takes place in a temperature range from KO to 150 ¹ C.

The hardening of insulated wire produced in this way from a polymer mixture according to the invention can also be carried out for a corresponding period of time in the temperature range from 150 to 300 ° C. within a casting mold under normal pressure or under a pressure of 5 to 20 kg / cm ² or more.

The optimum content of peroxide mixture in the polymer mixture according to the invention varies as a function on the type of peroxide mixture used, on the duration and temperature of the hardening heat treatment or the desired degree of curing of the polymer. When the mixture is at 150 to 200 C is to be maintained, per 100 parts by weight of polymer are preferably 0.2 to 20 parts by weight of peroxide mixture used. The duration of the hardening treatment varies depending on the one used Peroxide mixture and the heat treatment temperature used, being among those mentioned above Conditions to achieve sufficient curing 1 to 30 minutes are required.

Are polyolefins and copolymers or mixtures of such polymers consisting primarily of olefin for example those whose main proportion consists of ethylene or another olefin, but also those may contain other homo- or copolymers, for example copolymers of ethylene / vinyl acetate odei -älhylacrylat or mixtures thereof; Mixtures of polyolefin with paraffin; as elastomers Homo- or copolymers of butylene. Isoprene, isobutylene, ethylene or propylene, or mixtures of that. The polymer mixture according to the invention can optionally contain inorganic additives such as calcium carbonate, Contains clay, talc, diatomaceous earth, soot.

4.4 -thiobis- (6-tert.-butyl-m-cresol) can be added.

The wire insulations obtainable by the polymer mixture according to the invention are distinguished by excellent electrical and mechanical properties.

In the examples below, parts by weight are denoted by "T".

example

Various peroxyesters and diacyl peroxides are used to obtain liquid paraffin containing Peroxide mixtures in the mixing ratios set out in Table 1 below mixed with liquid paraffin.

The term "half-life" used here refers to the time required to reduce the initial concentration by half. In Table 2 below shows the half-lives at mixing and extrusion temperatures of 130 ° C. and at a hardening temperature of 190 "C, the from the measured half-lives of the Peioxidgcmischc were calculated according to Table 1.

In Table 3 below is the half-life of each of the peroxides listed in Table 1 mixed at 130 and 190 C, calculated from the half-lives measured at these temperatures these peroxides.

From Tables 1 to 3 it can be seen that the peroxide mixtures 1 a to 1 d according to Table 1 in the Mixing and extrusion temperatures of 130 C show almost the same half-lives as known ones

Polyolefin curing agent. d. H. Di-u-cumyl peroxide and 2,5-dimethyl-2 ', 5' ~ dWtert.-butyl-peroxy) -hexane, but that the first mentioned at the hardening temperature of 190 ° C show shorter half-lives than the latter. From the above it can be seen that invention. appropriate polymer mixtures, which contain the peroxide mixtures listed in Table 1, with approximately the same behavior as known mixtures do not cure prematurely at the mixing and extrusion temperatures, but that Currently their hardening required considerable time can be abbreviated.

Further details are given in the examples below.

From Table 3 it can be seen that tert-butyl peroxybenzoate and di (tert-butyl peroxy) adipate when used alone, each at the extrusion temperature of 130 C has a short half-life.

In the examples below, the melt index is given in gW min.

Example 2

Polyethylene (specific gravity 0.92; melt index 1.2) and ethylene / vinyl acetate copolymer (specific Weight 0.93; Melt index 3.0; 15 weight percent vinyl acetate) with the in Table I listed peroxide mixtures and mixed with the various listed in Table 4 below Additives in the specified proportions are added and the mixture obtained is heated at 110.degree processed with a roller to form a dispersion.

In Table 4, the patterns I a to Id each contain a peroxide mixture according to Table I with a content of 50 percent by weight liquid paraffin, and for the stated 2.0 T of a single peroxide are used as 4.0 T of a peroxide mixture. The patterns 2a. 2 b, 2 g and 2 h are comparison tests.

The mixtures according to Table 4 were at 190 ° C. for various pressing times to form films of a A thickness of 1.0 mm was pressed and the films obtained were in xylene at 120 ° C. for 12 hours immersed and then determined their swelling. The results obtained are in the following Table 5 listed.

The extent to which the polymer has cured results from the swelling of a pattern during treatment with an organic solvent such as xylene. The resistance of polymers to solvents can be viewed as the degree of hardening and is also a suitable means of determination the hardening effect of a peroxide.

From Table 5 it can be seen that in the comparison tests with known mixtures of samples 2a, 2b, 2g and 2h no hardening occurred, but that the hardening of the inventive mixtures of Trials 2c, 2d, 2e, 2f, 2i, 2j, 2k and 21 occurred within a short period of time.

Example 3

processed at 110 C with a roller to form uniform dispersions. Experiment 3a is a comparative experiment.

The mixtures listed in Table 6 were pressed at 180 ° C. for one minute under a pressure of 100 kg cm ² to give films with a thickness of 1.0 mm.

The resulting films were tested for tear strength and elongation at break on a tear strength tester determined. The results obtained are shown in Table 7 below.

From Table 7 it can be seen that the experiments 3 b to 3 h with mixtures according to the invention with respect to Curing speed and behavior at high temperature with regard to dimensional stability in comparison Compared to the comparison test 3a from a known polymer mixture, it performed much better.

Example 4

Polyethylene (specific weight percent 0.92: melt index 7.0) and ethylene Vinvlacelal copolymer (specific gravity 0.95; melt index 3.0; 25 percent by weight vinyl acetate) were with dialkyl peroxides. Peroxyesters and various additives mixed in various proportions, such as given in Table 8 below, and the mixtures obtained at 110 C "with a roller processed a dispersion.

The polymer mixtures according to Table 8 became films at 160 ° C. during various pressing times a thickness of 1.0 mm and the resulting films to determine the swelling, as in Example 2 described, for 12 hours in XvIoI of 120 ° C submerged.

Table ¹ ) below lists the times required to achieve a 70 ″ igen gelling, during which the test sample just swells according to the determination method listed in Table 5 according to Example 2 without going into solution

40 starts.

From Table 9 it can be seen ¹ that the test sample 4b. 4c, 4d. 4f and 4h made from polymer mixture according to the invention cured in a shorter period of time than the comparison sample 4a. 4c and 4g from known mixtures.

To determine the gelation, a sample of 0.5 g was taken from the 1.0 mm thick film, immersed in xylene at 120 ° C. for 12 hours and vacuum-dried at 80 ° C. for 8 hours.

50

Example 5

KK) T polyethylene. 50 T magnesium silicate, IT silicone oil, I T phenyl- / i'-naphthylamine and 6 T one by mixing 100 parts of dibutyl phthalate, 75 parts of di-ii-eumyl peroxide and 25 parts of DMt.-butyl-peroxy) adipate The peroxide mixture produced was processed into a dispersion as described in Example 2.

The resulting mixture was put into a press

cured for 10 minutes at 160 ° C. and then showed the following under various test conditions Characteristics:

Polyethylene (specific gravity 0.92; melting index 3.5) was mixed with various additives in various mixing ratios according to Table 6 below, with the experiments! a and 1 b in Table 6 were diirchgcführung with peroxide mixtures according to Table I. The mixtures obtained at room temperature:
Tear strength 2.25 kg / mm ²
Elongation at break MM) '! ·· «:

at 130 C:
Tear strength 0.35 kg nmr

HrtlcllHi'hniim · Till »,

The test of a water vapor at least 10 kg cm ^: cured sample gave the following test results:

at room temperature:

Tensile strength 2.15 kg nmr.

Elongation at break 5 (M) "":
at 130 C:

Tear strength 0.25 kg nmr.

Fracture elongation! 35O ⁰ O.

H e i s ρ i e 1 6

100 T ethylene propylene copolymer. 125 T magnesium silicate (Talc !. 5T zinc oxide. 'K) T lead oxide.Ί T Zinc stearal. 1 T of a polymer of 2.2.4-trinieth \ l-1.2-dihvdrochino! In as an anti-aging agent and H) T one by mixing 60 T di-i-cum> l peroxide. 40 T di (tert-butyl peroxy) adipate and HX) T Peroxide mixture obtained from dibutyl phthalate mixed by means of a 15 cm roller and the obtained The mixture was pressed in a press for 30 minutes at 160.degree. C. to give a film 1 mm thick hardened at the same time.

The film obtained showed a tear strength of 0.950 kg mnr and an elongation at break at room temperature of 650%.

Example 7

The test mixtures 2a and 2d were prepared on a Banburyw mixer. and the coating was made by means of an ordinary thermoplastic extruder with a cylinder diameter \ on 50 mm carried out.

The sections of coated stranded cable were connected to those shown in Table 10 below The speeds listed are passed through a curing pipe with a total length of 45 m, of which ίο 30 m filled with steam at a pressure of 1.5 kg cm and a temperature of approximately 200 ° C and 15 m served as a cooling pipe.

More isolated on the test sections obtained electrical cable, the swelling was determined in xylene at 120 C, as in Example 2 and the associated Table 5.

The results obtained are shown in Table 10 accordingly the standards in Table 5.

From Table 10 it can be seen that the coatings produced with the ίο crindurigsgemäRen mixture 2d cured faster than those from the well-known Yereleiehssiemisch 2a.

25 table

connection \ request

Ul

3 °

100 T ethylene propylene diene copolymer. I 50 T Di - ^ - cunnl peroxide Magnesium silicate. 1 T sulfur. K) T lead oxide. 1 T 15-dimethyl-2'.5-di-zinc stearate, 1 T phenyl -, <'- naphthalamine as anti-aging (iert.-butyl-pcroxyrrungsschutzmittel and 40 T of a peroxide mixture 35 hexane from 100 T of liquid paraffin. 50 T di-a-cumyl peroxide lert.-Butvl-peroxv- and 50 parts tert-butyl peroxybenzoate. were on a '

15-em roller mixed and the resulting mixture in pressed in a press for 20 minutes at 160 C to form a film i mm thick and at the same time hardened.

The film obtained showed a tear strength of 1,150 kg mm ² and an elongation at break of 650% at room temperature.

"0

70
30th

60

benzoate
Di- (tert-butyl-peroxy) -
adipate
"" Liquid paraffin 100 40
100 100 Id 40
100 Numbers = Gcvuchutcile 1.0
ΙΟ ' ³ 0.5 45 Table 2 Temperature trial la lh
5 ° 130 C 10 1.5
190 C 2.0 x 10 ' ³ 1.0 x 10 " ³ Ι.2
0.9- • ΙΟ " ³

Example 8

100 parts of the same copolymer as in Example 7, 100 parts of magnesium silicate, 10 parts of sulfur, 5 parts of lead oxide. 1 T zinc stearate. 1 p of phenyl / i-naphthalamine as an anti-aging agent and a peroxide mixture of 10 p of di-fi-cumyl peroxide, 3 p of tert-butyl peroxybenzoate and 10 p of liquid paraffin were mixed on a 15 cm roller and the mixture obtained in a press 55 j _a belle pressed for 30 minutes at 150 ^c C to a film with a thickness of 1 mm and cured at the same time.

The film obtained showed a tear strength of 1,050 kg mm ² and an elongation at break of 600% at room temperature.

Di-'i-cumylpcroxide Example 9 2.5-Dimethyl-2'.5'-di- (tert-butyl-

peroxyl-hcxan

Sections of a flexible electrical stranded _{cable 65 (crl.} Butyl-pcroxybcnzoate of 1 _{mm diameter sieve incised were DMtcrl} .; _Hul , _croxv) . _adipat in a layer thickness of 2 mm with the mixtures ^{J l}

of experiments 2a and 2d from example 2 coated. 'table 2 and V figures sni

Connection test temperature
\ V) C IW) C

2.2
1.5

0.34
0.35

1.0 · 10 ~ ² 0.9 · ΙΟ " ²

1.5
2.5

609 609/215

Table 4

connection

attempt

2a 2b

2d

2f

2μ

2h

10

2k 21

100 100 100 100

Polyethylene 100 100 100 H) O 100 100

Ethylene / vinyl acetate- ■ · - - -

Copolymer

4,4'-thiobis- (6-tert- 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2

butyl-m-cresol)

Ducumyl peroxide 2.0 - - - 2.0

2,5-dimethyl-2 ', 5'-di- ■ - 2.0 - - - 2.0

(tert-butyl-peroxy) -hexane

Test sample 1 a - - 4.0 - 4.0 - ■ -

according to example 1,

Table 1

Test sample Ib - - - 4.0 - ■ - 4.0 - -

according to example 1,

Table 1

Test sample Ic - - - 4.0 - - - - - 4.0

according to example 1,

Table 1

Test sample 1 d - - - - - 4.0 - - ■ - 4.0

according to example 1,

Table 1

Numbers = parts by weight.

Table 5

Pressing conditions

Experiment 2a 2 b

2d

2f

2h

2i

2k

15sec X X χ Δ O Δ χ X Δ O O Δ 30 sec X X Δ O O O X χ O O O O 45sec X X O O O O X Δ O O O O 60 sec Δ Δ O O O O Δ O O O O O

190 ⁰ C

Explanation of symbols: χ - Completely solved.

Δ = Partly loosened, partly swollen.
O = weakly loosened, swollen.

Table 6

connection

attempt

3a 3b

c

3d

3e

3f

3g

Polyethylene / vinyl acetate copolymer (specific weight 0.93, Melt index 6.0) 4,4'-thiobis (6-tert-butyl-m-cresol) dicumyl peroxide Test sample 1 a according to Example 1, table Test sample 1 b according to Example 1, table Numbers = parts by weight.

100 100 100 100 60
40 60
40 60
40 0.2
2.0 0.2
1.0 0.2
5.0 0.2
10.0 0.2 0.2 O,: 1.0 5.0 10

11th
table 7 attempt 21 30 273 .Ul 3e 12th 3 g 3 h test 3 a 1.80
510 1.45
450 1.40
500 1.55
600 1.80
550 .lh .u- 0.30
350 0.01
150 3f 0.20
350 0.30
300 At room temperature (25 ° C)
Tear strength, kg / mm ²
Elongation at break,% 0.00
0.00 1.60
550 1.75
520 O Δ 1.50
520 O O At 140 C.
Tear strength, kg / mm ²
Elongation at break,% X 0Ό2
100 0.20
200 0.05
200 Swelling
(Test according to example 2,
Information according to table 5) Δ O O

Table 8

connection

attempt

4a 4b 4c -Id 4c

4f

4g 4h

4i

4y

Polyethylene ethylene / vinyl acetate copolymer 4,4'-thiobis- (6-tert-butylm-cresol) Di-u-cumyl peroxide di- (tert-butyl-peroxyi-adipate Dibutyl phthalate 100 100 100 100 100 100 100 100 100 - - - - - - - - - - - 100 100 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.5 0.5 0.1

1.8 1.8 1.8 1.8 - 0.2 0.4 0.8 3.0 3.0 3.0 3.0 1.2 - 0.1
3.0 1.0 1.0

5.0 -

1.8 0.5 0.5 5.0 5.0 0.3 0.3

5.0 5.0 3.0 3.0

Table 9

attempt

4a 4b 4c 4d 4e 4f 4g 4h 4i 4j 4k

Duration up to 70% gelation at 160 ^° C., min 10.0 9.0 7.2 6.0 4.0 60.0 55 4.0 2.0 40 35

Table 10

test

Swelling (test according to example 2, information according to table 5) Polymeruemisch ccnia'ß Example 2. Table 4
2a 2d

Flow rate. Hardening zone m min
17.0 20.5 24.0 27.5 17.0

20.5

24.0

■ n

-its

Claims (1)

Claim: Process for the production of foils and insulated wire, characterized in that a mixture of at least one dialkyl peroxide and at least one peroxyester in a weight ratio of 6: 4 to 7: 3 in an amount of 0.1 to 10 parts by weight of the sum of the two peroxides with 100 parts by weight a polyolefin or copolymers with a predominant olefin content or a mixture of such polymers at 80 to 150 ° C, if necessary, extruded onto an electrical conductor and the coated conductor is then ^{cured at a temperature of 150 to MX) 13} ° C.