CA1271585A - Process for cross-linking or degrading polymers and shaped articles obtained by this process - Google Patents
Process for cross-linking or degrading polymers and shaped articles obtained by this processInfo
- Publication number
- CA1271585A CA1271585A CA000512236A CA512236A CA1271585A CA 1271585 A CA1271585 A CA 1271585A CA 000512236 A CA000512236 A CA 000512236A CA 512236 A CA512236 A CA 512236A CA 1271585 A CA1271585 A CA 1271585A
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- cross
- group
- linking
- peroxide
- polymers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/14—Peroxides
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F8/00—Chemical modification by after-treatment
- C08F8/50—Partial depolymerisation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2810/00—Chemical modification of a polymer
- C08F2810/20—Chemical modification of a polymer leading to a crosslinking, either explicitly or inherently
Abstract
A B S T R A C T
This disclosure relates to a process for cross-linking polymers, e.g.
polyethylene, or degrading polymers, e.g. polypropylene, using peroxides having at least one carbon-carbon double bond in the molecule, e.g.
1-(t-butyl peroxy isopropyl)-3-isopropenylbenzene.
Incorporation of the peroxides into the polymer may be carried out at relatively high temperatures without the risk of premature decomposition of the peroxide, thus allowing easy processability of the polymer mass prior to cross-linking or degradation. The polymeric endproducts obtained are odourless and do not display blooming.
This disclosure relates to a process for cross-linking polymers, e.g.
polyethylene, or degrading polymers, e.g. polypropylene, using peroxides having at least one carbon-carbon double bond in the molecule, e.g.
1-(t-butyl peroxy isopropyl)-3-isopropenylbenzene.
Incorporation of the peroxides into the polymer may be carried out at relatively high temperatures without the risk of premature decomposition of the peroxide, thus allowing easy processability of the polymer mass prior to cross-linking or degradation. The polymeric endproducts obtained are odourless and do not display blooming.
Description
L~
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A~D Ig6l R
Process for cross-linking or degrading polymers and ~haped articles ob-tained by this process rhe lnvention relates to a process for cross-linking or degradlng polymers, use being made of an organic peroxide which has at least ona carbon-carbon double bond in the molecule. ~he invention also relate~ to shapsd articles obtained by this process.
A process of the above type is disclosed in United States Patent Specifi-cation No. 3 g80 629. According to it the use as cross-linking agent of unsa~urated peroxyketals leads to cross-linked polymers that are practic-ally odourless and do not exhibit blooming.
Polymers having those properties are desirable in that, as is generallyknown, the more or less volatile decomposition products form~d from dicumyl peroxide, which is often used in practice for cross-linking and degradation purposes, will lead to polyme,rs which have an unpleasant smell and display blooming, which i9 objectionable to their applicability, for instance as packaging material for foodstuffs.
To the peroxyketals described in said United States Patent Speclfication, however, there is the disadvantage that the temperature at which they are incorporated into a polymer is subject to restrictions in view of the risk of premature decomposition. l'hey are therefore not suitable at all to be used as a degradant for polymers such as polypropylene; and when they are used as a cross-linking agent, this drawback manifests itself parti~ularly in the cross-linking of those polymers, such as ela tomsrs, lnto which the peroxide, and other additives, if desired, are to be mixed in at elevated temperature, prior to the polymer mass being shaped; to prevent premature cross-linking ~scorching) the temperature at which these well-known per-oxides are allowed to be processed i9 relatively low, which is detrimental to the vl~cosity and, hence, the processability of the polymer mass to be cross-linked. As cross-linking agent these peroxyketals are therefore no sat$sfactory alternative to dicumyl peroxide.
Ths invention envisages the elimination of these drawback~. lt provides peroxide~ that are not subject to th0 temp0rature limitations of sald peroxyketals, but do retain the favourable proparties of these peroxyketals , j ~
~7~5l35 with respect to smell and blooming of the polymerlc endproducts (see above) and as cross-linking and degrading agent form a good alternative to dlcumyl peroxide.
l'he proces~ according to the invention is characterized in that the per-oxide corresponds to the general structural formula ~ R1 Rz ~ C - 0 - ~ - C - R7 1 ~I?
H m K4 X6 n where m = 0,1 or 2;
n a 1,2 or 3;
m+n = < 3;
Rl = H or an alkyl group containing 1-3 carbon atoms;
R2 ~ an alkyl group containing 1-4 carbon atoms;
R3-R6- alkyl groups containing 1-10 carbon atoms;
R7 = an alkyl group containing 1-10 rarbon atoms which is sub-stituted or not with a C1-1o alkoxy group, a C1-1~ acetoxy group or a hydroxyl group, or represents a group A of the general formula . Rg Rs - C ~ ¦ ~
where p = 1 or 2 and Ra and Rq have the meaning indicated above for Rz and Xl, respectively;
with the proviso that in the case of disubstitution the aromatic ring sub-stituents sre not ortho to each other and in the case of trisub~titutlon are not in three adjacent positions, and that when m=0, ~7 represents a group A.
rt should be noted that several of the peroxides to be used accordlng to the present invention are known -EroM SU 757 529, SU 887 578, JP 60/11349, JP 60J13828 and ~P 60Jlg762. Lt is described that those peroxides may be 1~7~58S
AC~ 1961 R
applied as monomers in the preparation of peroxide groups-containing poly-mers. The present use is neither disclosed in these publications nor can it be derived therefrom.
lt should further be noted that for the use as cross-linking agent for rubber an unsaturated peroxide is known from WP 8 00~ 2B5, viz, l-meth-acrylate-l-t-butyl peroxyethane. Upon repetition of a process on the basis of the data known from this disclosure, however, it was not found possible to prepare this peroxide.
Cross-linking of polymers As mentioned above, the present peroxides may with advantage be used -In high-melting polymers, such as elastomers, without the risk of premature cross-linking during the processing phase, i.e. the phase of mixing in of the peroxide and moulding of the polymer mass immediately preceding the cross-linking phase. As examples of these polymers may be mentioned:
polyethylene, copolymers of ethylene and propylene (EPM) and copolymers of ethylene, propylene and a diene monomer (EPDM). But the advantages to the present peroxides are not limited to use in high-melting polymers. The present peroxides also may with advantage be used in low-melting polymers.
As a result, the polymer mass obtained may advantageously be exposed to relatively high temperatures, so that a low viscosity and, hence, satis-factory processability are obtained.
Examples of polymers to be cross-linked in accordance with the present process, in addition to the polymers mentioned before, include chlorosul-phonated polyethylene, chlorinated polyethylene, polybutene-l, polyiso-butene, ethylene vinyl acetate copolymers, polybutadiene, polyisoprene, polychloroprene, butadiene styrene copolymers, natural rubber, polyacrylate rubber, butadiene acrylonitrile copolymers, acrylonitrile-butadiene-styrene terpolymers, silicone rubber, polyurethanes and polysulphides.
lt is preferred that the present process should be applied for cross-linking polyethylene, EPM and EPDM.
To the polymer to be cross-linked is generally added 0~1-10Vb by weight, and preferably 1-3Vb by weight of the present peroxide.
~oreover, to the polymer to be cross-llnked there may be added various agents commonly employed in cross-linking processes, such as antioxidants, pigments, UV stabiliæers, fillers, plasticizers, etc. in amounts commonly used for these purposes.
~CD lg61 R
The temperature at which the present peroxide9 may be mixed into polymeric material without there occurring any premature cross-llnklng i8 generally in the range of 25v to 130V~; the temperature at which subsequent cross-llnklnK ls carrled out is generally ln the range of lS0V to 220~C, preferably 160U-l9OvC.
For carrying out the process accordlng to the lnvention use may be made of the techniques commonly applied in cross-linking reactions in appropriate equipment.
In thls connection mention is made of the known fact that cross-linked polyethylene is a very suitable material to be applied as insulating materlal in the wlre and cable lndustry.
Degradation of polymers As ls known for cases where easy processlng ls required, as in melt spinning at high shear rates, propylene-based polymers prepared by the Ziegler-~atta process should be degraded, because of a too hlgh molecular weight and hence a too high viscosity. By heating the polymer to a tempera-ture in the range of 180~ to 350~C ln the presence of a radlcal inltlatlng compound a reduction of the molecular weight and a narrowed molecular weight distribution are obtained. Polymers thus degraded satisfy the requirements of ease of processing to be met in the production of fibres, fllms and other shaped artlcles.
Lhe present peroxidss have been found very suitable degradants. As polymers that lend themselves to be degraded may be mentloned the well-known (co)-polymers of propylene: polypropylene and copolymers of propylene and ethylene, l-butene or l-hexene. In actual practlce lt is mostly the degradation oE polypropylene that is applied.
Degradation may be carrled out in the usual manner. In the presence of one of the present pe}oxides, the (co)polymer is heated to a temperature above the melting polnt of the ~co)polymer and above the decomposition tempera-ture of the peroxide. This temperature will generally be in the range of180~ to 3SO~C, preferably 200~ to 250~. The heatlng tlme is as a rule be-tween 0,1 and 30 mlnutes, preferably between 0,5 and 5 minutes.
The pre~ent peroxlde wlll generally be added to the (co)polymer to be degraded in an amount of 0,001 to 2~o by weight, preferably 0,01 to 0,5~/O by welght, calculated on the amount of ~co~polymer. rn addItlon antioxldants andlor UV stabilizers, usually employed for polymer degrsdation, may be ~2D7~ 35 added in the usual amount to the (co)polymer to be de~raded. As examples of 3uitable ant$oxidants may be mentioned esters of ~-(3,S-di-tert.butyl-4-hydroxyphenyl~propionic acid, more particularly the esters thereof with pentaerythrite or octadecanol, 1,3,5-trimethyl-2,4,6-tris(3',5'-di-tert.~
butyl-4'-hydroxyphenyl)benzene, 4-hydroxymethyl-2,6-di-tert.butylphenol, tris-(2'-methyl-4'-hydroxy-5'-tert.butylphenyl)butane, tetrakisl3-(3,5-di-tert.butyl-4-hydroxyphenyl)propionyloxymethylJmethane, 2,6-di-tert.butyl- _ p-cresol and 3,5-dimethyl-4-hydroxybenzyl thioglycolic stearyl ester. As suitable UV rays absorbing agents may be mentloned 2-(2'-hydroxy-3',5'-di-tert.amylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert.butylphenyl)-5-chlorobenzotriazole and 2-hydroxy-4-n-octyl-oxy-benzophenone.
The degradation may be carried out in equipment usually employed for this purpose, such as extrusion apparatus.
The present peroxides ~he peroxides to be used according to the invention correspond to the abovs-described general Formula 1. Eor practical considerations with regard to the magnitude oE the molecular weight and synthetic accessibility it is preferred that when ~-1 or 2 andtor p=l or 2 use should be made of per-oxides where the substituted vinyl group or groups represent isopropenyl ~R1 = H, R2 = ~H3 andlor Ra z ~3,Rg = H) and the aromatic radical or radicals represent the cumyl structure (R3 - R4 = C~3 andlor ~s = X
CH3~.
lhe preparation may be carried out in the usual manner by reactlng a t-alcohol with hydrogen peroxide in an acid medium to ~orm the corresponding t-alkylhydroperoxide and converting the resulting compound with a t-alcohol, also in an acid medium, into the peroxide; at least one of the two t-alcohols used should be unsaturated.
Examples of saturated t-alcohols to be used in the preparation o-E the present peroxides include t-butyl alcohol, t-a~yl alcohol, 2-hydroxy-2-methylpentane, cumyl alcohol (=~-hydroxyisopropylbenzene), 1,3-bis(~-hydroxyisopropyl)benzene, 1,4-bis(~-hydroxyi~opropyl)benzene and 1,3,5-tris-(~-hydroxyisopropyl)benzene.
Examples of unsaturated t-alcohols to be used in the preparation of the present peroxides include l-~-hydroxyisopropyl)-3-isopropenylbenzene, 1-(~-hydroxyisopropyl)-4-isopropenylbenzene, 1-~-hydroxyisopropyl)-3,5-bis-(isopropenyl)benzene, 1,3-bis(~-hydroxyisopropyl)-5~isopropenyIb~nzene and ~ hydroxyisopropyl)-2,4-bl9(isopropenyl)benæene. Preparation of the~e unsaturated t-alcohols may be carried out by partlal dehydration of the corresponding diols or triols in the manner described in US 3 622 636 for the preparation of 1-(~-hydroxyisopropyl)-3-isopropenylbenzene and 1-(~-hydroxyisopropyl)-4-isopropenylbenzene from, respectively, 1,3-bis(~-hydroxyisopropyl~benzene and 1,4-bis(~-hydroxyisopropyl)benzene, Examples of suitable peroxides where in the general ~ormula I m~O are:
1-(cumyl peroxy isopropyl)-3-isopropenyIbenzene and 1-(cumyl peroxy isopropyl)-4-i~opropenylbenzene.
Examples of suitable peroxides where in the general Formula m~O are:
l-(t-butyl peroxy isopropyl)-3-isopropenylbenzene, 1-(t-butyl peroxy isopropyl)-4-isopropenyIbenzene, 1,3-di(t-amyl peroxy isopropyl)-5-isopropenylbenzene, 1-(t-butyl peroxy isopropyl)-3,5-bis(isopropenyl~benzene, 1-(t-butyl peroxy isopropyl)-2,4-bis(isopropenyl)benzene and 1,3-di(t-butyl peroxy isopropyl)-5-isopropenyIbenzene.
~articularly suitable for use in the process according to the invsntion are those peroxides where m has the value of 1 and, when R7 represents the group A, p also has the value of 1. More particularly preferred are those peroxides where R1 = H, Rz = R3 = Rl, = Rs = R~ = a methyl group and, when ~ X7 represents a group A, Rg = a methyl group and Rg s H.
; The present peroxides also may be used in combination with each other.As regards the structure of the present peroxides it should still be noted that steric requirements lead to the aromatic substituents not being ortho to each other in the case of disubstitution and to their not being in three adjacent positions in the case of trisubstitution . The invention will be further described in the following examples.
Example 1 Preparation of 1-(t-butyl peroxy isopropyl)-3-isopropenylbenzene (Com-pound 1) To a mixture of equimolar amounts of t-butyl hydroperoxide ~32 g~ and 1-(~-hydroxyisopropyl)-3-isopropenylbenzene (57 g) stirred at 30VC ~here were added 1,32 ml of an aqueous solution of 20% by weight of perchloric acid.
Over a period of 30 minutes MgSO4.2H20 was added portionwise up to an amount of in all 26,3 g, after which the rea~tion mixture was stirred for 2 hours at 35~C. Then quf~icient water was added to dissolve all oE the ~:2715i~
magnesium sulphate. 'rhe or~anic phase was separated, washed with aqueous NaO~ and finally with water. Obtained were 80 g of a colourless liquld (yield 90~/0) having an active oxygen content of 6~02V/o (calc. 6,44~/o). 'rhe structure was confirmed by NMR and IR analyses.
Example 2 Preparation of 1-~t-butyl peroxy isopropyl)-4-isopropenYlbenzene ~Com~
pound 2) The same procedure was carried out as described in Example 1, except that use was made of equimolar amounts of 1-(a-hydroxyisopropyl)-4-isopropenyl-benzene and t-butyl hydroperoxide. Obtained wa~ a colourless liquld ~yield 90~/0) having an active oxygen content of 5~58U/o (calc. 6~44~/o~ lrhe structurewas conflrmed by NMR and IR analyses.
Example 3 Preparation of Compound 3 'fhe same procedure was carriad out as described in Example 1, except that use was made of equimolar amounts of 1-(~-hydroxylsopropyl)-3-isopropenyl-benzene and l-(a-hydroperoxyisopropyl)-3-isopropenylbenzene. Obtained was a colourless liquid (yield 70~tO) having an active oxygen content of 3,81~/~
(calc. 4~56~/o). lrhe structure was confirmed by ~MR and IX analyses.
ExamPle 4 Preparation of Compound 4 The same procedure was employed as described in Example 1, sxcept that use was made of equimolar amounts of 1-(~-hydroxyisopropyl)-4-isopropenyl-benzene and l-(a-hydroperoxyisopropyl~-4-isopropenyIbenzene. Obtained was a viscous liquid from which the product was isolated as white crystals by crystallization with diethyl ether. 'rhe product was obtained in a yield of 60uto and had a melting point of 82V-85~C and an active oxygen content of 4~20~o (calc. 4t56~to). ~'he structure was characterized by NMR and rR
analyses.
Example 5 Preparation of l-(cumyl peroxy isopropyl)-4-isopropenyIbenzene (Com-pound 5) The same procedure was used as described in Example 4, except that use was made of equimolar amounts of 1-(~-hydroxyisopropyl)-4-isopropenylbenzene and cumyl hydroperoxide. Obtained were white crystals (yield 70æ) having a melting point of 40VC and an active oxygen content of 4,34% (calc. 5,15). a The structure was confirmed by NMR and IR analyses.
Example 6 Preparation of 1,3-di(t-butYl peroxy i30propyl)-S-isopropenyl~enzene (Com-pound 6) To a mixture of 1,3-bis(a-hydroxyisopropyl)-5-isopropenylbenzene ~14 g), t-butyl hydroperoxide (lS g) and hexane~50 ml) stirred at 35VC there were added 0,55 ml of an aqueous solution of 20V/o by weight of perchloric acid and subsequently ~gS04.2B20 (10,6 g), the latter in a portionwise manner, after which the reaction mixture was stirred for 3 hours at 40~C. Then suf-ficient water was added to dissolve all of the magnesium sulphate. rhe organic phase was separated, washed with aqueous NaOH and finally with water. After removal of the hexane from the organic phase under reduced pressure, 22 g of a yellow oil were obtained (yield 9S~/O) having an active ; ~ oxygen content of 8,29% (calc. 8~47U/o). 'rhe structure was confirmed by NMR
and IR analyses.
Example 7 Preparation of l-(t-butyl peroxy isopropyl~-3~5-bis~isopropenyllbenzene ~CoMPound 7) The same procedure was employed as described in Example I, sxcept that use was made of equimolar amounts of 1-(~-hydroxyisopropyl~-3,5-bis(iso-propenyl)benzene and t-butyl hydroperoxide. Obtained was a yellow liquid (yield 95~h) having an active oxygen content of 5,12~ (-calc. 5~56~/o). 'rha structure was confirmed by NMR and IR analyses.
~8~ 7~L~3~
Example 8 ! f the peroxides described in the preceding examples the permissible processing temperature was determined as follow~.
~ver a period of 5 minutes 0,OI equivalent of the peroxide was mixed with 100 g of ethylene-propylene copolymer (E~? on a roll mill at a friction of 1:1,2 and at a temperatu}e of 50~-70VC. Of the resulting mixture the cross-linking behaviour was subsequsntly determined with the aid of a ~'ottfert Elastograph in the manner described in Kautschuk und Gummi Z9(5/6) 341-35Z
(1976). In this determination the mixture to be cross-linked i9 embedded in a heated chamber the lower half of which is oscillatory. During cross-linking the increase is registered in the torque on the lower chamber half as a result of the increase in viscosity of the cross-linking mixture as a function of time. '~he increase in torque is expressed in the parameters t1o and tgo which represent the time necessary under the given conditions to bring about respectively lOU/o and 90~/~ of the increase in torque (~torque).
The determinations were carried out at 170~C, using being made of a slit width of 0,2 mm, an oscillation angle of about 0,S~ and an oscillation frequency of 0,83 Hz. The results are given in l'able 1. For comparison also the values are mentioned of analogous experiments carried out using 0,01 mole of dicumyl peroxide tCompound A) and 0,01 mole of 1-phenyl-3,3-di(t-butylperoxy)-1-propene (Compound B: an unsaturated peroxide according to US 3 9gO 629).
From the t1o and tgo values found it appears that the processing range of the present peroxides is similar to that of dicumyl peroxide (A) and in several cases even exceeds it, whereas the processing range of the peroxide (B) disclosed in US 3 980 629 i9 narrower.
Table 1 _ _ Compound tlo (min) tgO (min) 0,6 5 6 0,8 7 7 0,9 8 j A L 0'7 7 Example 9 l'he peroxides described in Examples l and 6 were tested as cross-linking agent for polyethylene. To that end 0,01 equivalent of each peroxide was mixed on a roll mill for 3 minutes at 120~-130VC with 100 g of low-density polyethylene ~Lupolen~ 1810 H, ex BAS~`).
l'he cross-linking behaviour was determined with the aid o~ the ~ottfert Elastograph described in Example 8. The t1o, tg~ and ~torque values ob-tained are listed in Table 2. The Table also gives the compression moulding temperature and the compression moulding time applied in the cross-llnking processes.
The cross-linked products obtained were tested for odour and bloomlng and the following propertie6 were measured.
- l'he tensile strength, the lO0, 200 and 300~/0 moduli and the elongation at break were determined in accordance with IS0-standard ~37 type l.
- The hardness was determined in accordance with ASTM D2240.
- 'rhe gel fraction was measured in conformity with the standards B5 5468-lg77 and A~IIASTM ~2765-68(1972~. In this test the percentage polymer is determined which does not dissolve in boiling xylene under the test conditions. l'his parameter is a measure of the degree of cross-linking and hence of the efficiency of the peroxide.
The results are given in Table 2. It also mentions the results of a com-parative experiment carried out wlth 0,01 mole of dicumyl pe~oxide (Com-pound A).
The results obtained show that the peroxides according to the invention are a good alternative to dicumyl peroxide. Furthermore the remarkably high value o ~torque obtained with Compound 6 should be noted. l~his high value is surprising in view of the fact that Compounds l, 6 and A were used in equivalent amounts (i.e. 0,01 mole of Compounds l and A and 0,005 mole of Compound 6).
~:71585 Table 2 Compound 1 6 A
_ . .
t1o (min) 1,2 1,3 lt1 tgo ~min) 8,2 8,7 8,8 ~torque (~m) 0,51 0,67 0,48 Compression moulding temp. ~C) 180 18~ 170 Compression moulding time ~min) 20 20 20 Tensile strength (~Pa) 21,5 19,7 19,7 ~odulus 100~/~ (MPa) 7,6 8,1 7,8 Modulus 200~/o (MPa) 7,9 8,6 8,2 Modulus 300~b ~Pa) 9,7 12,5 10,3 ~long. at break (V/o~ 450 360 420 Hardness ~Shore D ~9 45 49 Gel fraction (J/O) 86 88 90 Odour none none yes ~looming after 1 week none none yes To further demonstrate that the peroxides according to the invention have desirable properties as regards their decomposition products the following experiments were carried out.
Samples of the cross-linked products obtained in Example 9 were exhaustively extracted with dichloromethane at reflux temperature.
Gaschromatographic analysis of the resulting solutions showed that no aromatic compounds were present in the solutions from the products prepared with Compounds 1 and ~ whereas in the solution from the product prepared wi~h dicumyl peroxide (Compound A) acetophenone and cumyl alcohol could be clearly identified.
In another set of experiments the cross-linking reactions described in Example 9 were repeated, except that in stead of the ~-ottfert Elastograph use was made of a closed reactlon vessel coupled to a gas chromatograph ~ (head space gas chromatography). At regular time intervals gas samples from the reaction vessel were analyzed for aromatic decomposition products. In the case of Compounds 1 and 6 no aromatic decomposition products could be detected wherea~ in the case of dicumyl peroxide (Compound A) acetophenone and cumyl alcohol could be clearly identified.
Example 10 ~'he peroxide described in Example 1 was tested as degradant for polypropylene. 'rhe following procedure was used.
Unstabilized polypropylene (Moplen~ FLS 20, ex. Himont; melt ~low index (230~C, 2,1~ kg): 1,8 g/10 min) was mixed with the peroxide in a tumble mixer. The resulting product was processed through a single ~crew extruder at elevated temperature. After cooling to room temperature, the extrudate was granulated and of the resulting granules the melt flow index was determined.
The amounts of peroxide used, the extrusion temperatures applied and the melt flow indices obtained are listed in Table 3. From the indices obtained it appears that the peroxlde according to the invention Is a suitable poly-propylene degradant. ln addition to this it was observed that the extrudate obtained was odourles~ whereas in a comparative experiment carried out with dicumyl peroxide as degradant an unpleasantly smelling extrudate resulted.
Table 3 Amount of peroxide Extrusion temp. Melt flow index (wt.~to) ( C) (gl10 min) 0,0171 200 5,7 (1) 0,0171 250 8,2 11) 0,0855 200 28,1 (1) 0,0855 250 35,1 (1) 0,428 200 84,8 (2) 0,428 250 209 (2) _ (1) Measuring conditions: 230~C12,16 kg
7~:~i8~;
A~D Ig6l R
Process for cross-linking or degrading polymers and ~haped articles ob-tained by this process rhe lnvention relates to a process for cross-linking or degradlng polymers, use being made of an organic peroxide which has at least ona carbon-carbon double bond in the molecule. ~he invention also relate~ to shapsd articles obtained by this process.
A process of the above type is disclosed in United States Patent Specifi-cation No. 3 g80 629. According to it the use as cross-linking agent of unsa~urated peroxyketals leads to cross-linked polymers that are practic-ally odourless and do not exhibit blooming.
Polymers having those properties are desirable in that, as is generallyknown, the more or less volatile decomposition products form~d from dicumyl peroxide, which is often used in practice for cross-linking and degradation purposes, will lead to polyme,rs which have an unpleasant smell and display blooming, which i9 objectionable to their applicability, for instance as packaging material for foodstuffs.
To the peroxyketals described in said United States Patent Speclfication, however, there is the disadvantage that the temperature at which they are incorporated into a polymer is subject to restrictions in view of the risk of premature decomposition. l'hey are therefore not suitable at all to be used as a degradant for polymers such as polypropylene; and when they are used as a cross-linking agent, this drawback manifests itself parti~ularly in the cross-linking of those polymers, such as ela tomsrs, lnto which the peroxide, and other additives, if desired, are to be mixed in at elevated temperature, prior to the polymer mass being shaped; to prevent premature cross-linking ~scorching) the temperature at which these well-known per-oxides are allowed to be processed i9 relatively low, which is detrimental to the vl~cosity and, hence, the processability of the polymer mass to be cross-linked. As cross-linking agent these peroxyketals are therefore no sat$sfactory alternative to dicumyl peroxide.
Ths invention envisages the elimination of these drawback~. lt provides peroxide~ that are not subject to th0 temp0rature limitations of sald peroxyketals, but do retain the favourable proparties of these peroxyketals , j ~
~7~5l35 with respect to smell and blooming of the polymerlc endproducts (see above) and as cross-linking and degrading agent form a good alternative to dlcumyl peroxide.
l'he proces~ according to the invention is characterized in that the per-oxide corresponds to the general structural formula ~ R1 Rz ~ C - 0 - ~ - C - R7 1 ~I?
H m K4 X6 n where m = 0,1 or 2;
n a 1,2 or 3;
m+n = < 3;
Rl = H or an alkyl group containing 1-3 carbon atoms;
R2 ~ an alkyl group containing 1-4 carbon atoms;
R3-R6- alkyl groups containing 1-10 carbon atoms;
R7 = an alkyl group containing 1-10 rarbon atoms which is sub-stituted or not with a C1-1o alkoxy group, a C1-1~ acetoxy group or a hydroxyl group, or represents a group A of the general formula . Rg Rs - C ~ ¦ ~
where p = 1 or 2 and Ra and Rq have the meaning indicated above for Rz and Xl, respectively;
with the proviso that in the case of disubstitution the aromatic ring sub-stituents sre not ortho to each other and in the case of trisub~titutlon are not in three adjacent positions, and that when m=0, ~7 represents a group A.
rt should be noted that several of the peroxides to be used accordlng to the present invention are known -EroM SU 757 529, SU 887 578, JP 60/11349, JP 60J13828 and ~P 60Jlg762. Lt is described that those peroxides may be 1~7~58S
AC~ 1961 R
applied as monomers in the preparation of peroxide groups-containing poly-mers. The present use is neither disclosed in these publications nor can it be derived therefrom.
lt should further be noted that for the use as cross-linking agent for rubber an unsaturated peroxide is known from WP 8 00~ 2B5, viz, l-meth-acrylate-l-t-butyl peroxyethane. Upon repetition of a process on the basis of the data known from this disclosure, however, it was not found possible to prepare this peroxide.
Cross-linking of polymers As mentioned above, the present peroxides may with advantage be used -In high-melting polymers, such as elastomers, without the risk of premature cross-linking during the processing phase, i.e. the phase of mixing in of the peroxide and moulding of the polymer mass immediately preceding the cross-linking phase. As examples of these polymers may be mentioned:
polyethylene, copolymers of ethylene and propylene (EPM) and copolymers of ethylene, propylene and a diene monomer (EPDM). But the advantages to the present peroxides are not limited to use in high-melting polymers. The present peroxides also may with advantage be used in low-melting polymers.
As a result, the polymer mass obtained may advantageously be exposed to relatively high temperatures, so that a low viscosity and, hence, satis-factory processability are obtained.
Examples of polymers to be cross-linked in accordance with the present process, in addition to the polymers mentioned before, include chlorosul-phonated polyethylene, chlorinated polyethylene, polybutene-l, polyiso-butene, ethylene vinyl acetate copolymers, polybutadiene, polyisoprene, polychloroprene, butadiene styrene copolymers, natural rubber, polyacrylate rubber, butadiene acrylonitrile copolymers, acrylonitrile-butadiene-styrene terpolymers, silicone rubber, polyurethanes and polysulphides.
lt is preferred that the present process should be applied for cross-linking polyethylene, EPM and EPDM.
To the polymer to be cross-linked is generally added 0~1-10Vb by weight, and preferably 1-3Vb by weight of the present peroxide.
~oreover, to the polymer to be cross-llnked there may be added various agents commonly employed in cross-linking processes, such as antioxidants, pigments, UV stabiliæers, fillers, plasticizers, etc. in amounts commonly used for these purposes.
~CD lg61 R
The temperature at which the present peroxide9 may be mixed into polymeric material without there occurring any premature cross-llnklng i8 generally in the range of 25v to 130V~; the temperature at which subsequent cross-llnklnK ls carrled out is generally ln the range of lS0V to 220~C, preferably 160U-l9OvC.
For carrying out the process accordlng to the lnvention use may be made of the techniques commonly applied in cross-linking reactions in appropriate equipment.
In thls connection mention is made of the known fact that cross-linked polyethylene is a very suitable material to be applied as insulating materlal in the wlre and cable lndustry.
Degradation of polymers As ls known for cases where easy processlng ls required, as in melt spinning at high shear rates, propylene-based polymers prepared by the Ziegler-~atta process should be degraded, because of a too hlgh molecular weight and hence a too high viscosity. By heating the polymer to a tempera-ture in the range of 180~ to 350~C ln the presence of a radlcal inltlatlng compound a reduction of the molecular weight and a narrowed molecular weight distribution are obtained. Polymers thus degraded satisfy the requirements of ease of processing to be met in the production of fibres, fllms and other shaped artlcles.
Lhe present peroxidss have been found very suitable degradants. As polymers that lend themselves to be degraded may be mentloned the well-known (co)-polymers of propylene: polypropylene and copolymers of propylene and ethylene, l-butene or l-hexene. In actual practlce lt is mostly the degradation oE polypropylene that is applied.
Degradation may be carrled out in the usual manner. In the presence of one of the present pe}oxides, the (co)polymer is heated to a temperature above the melting polnt of the ~co)polymer and above the decomposition tempera-ture of the peroxide. This temperature will generally be in the range of180~ to 3SO~C, preferably 200~ to 250~. The heatlng tlme is as a rule be-tween 0,1 and 30 mlnutes, preferably between 0,5 and 5 minutes.
The pre~ent peroxlde wlll generally be added to the (co)polymer to be degraded in an amount of 0,001 to 2~o by weight, preferably 0,01 to 0,5~/O by welght, calculated on the amount of ~co~polymer. rn addItlon antioxldants andlor UV stabilizers, usually employed for polymer degrsdation, may be ~2D7~ 35 added in the usual amount to the (co)polymer to be de~raded. As examples of 3uitable ant$oxidants may be mentioned esters of ~-(3,S-di-tert.butyl-4-hydroxyphenyl~propionic acid, more particularly the esters thereof with pentaerythrite or octadecanol, 1,3,5-trimethyl-2,4,6-tris(3',5'-di-tert.~
butyl-4'-hydroxyphenyl)benzene, 4-hydroxymethyl-2,6-di-tert.butylphenol, tris-(2'-methyl-4'-hydroxy-5'-tert.butylphenyl)butane, tetrakisl3-(3,5-di-tert.butyl-4-hydroxyphenyl)propionyloxymethylJmethane, 2,6-di-tert.butyl- _ p-cresol and 3,5-dimethyl-4-hydroxybenzyl thioglycolic stearyl ester. As suitable UV rays absorbing agents may be mentloned 2-(2'-hydroxy-3',5'-di-tert.amylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert.butylphenyl)-5-chlorobenzotriazole and 2-hydroxy-4-n-octyl-oxy-benzophenone.
The degradation may be carried out in equipment usually employed for this purpose, such as extrusion apparatus.
The present peroxides ~he peroxides to be used according to the invention correspond to the abovs-described general Formula 1. Eor practical considerations with regard to the magnitude oE the molecular weight and synthetic accessibility it is preferred that when ~-1 or 2 andtor p=l or 2 use should be made of per-oxides where the substituted vinyl group or groups represent isopropenyl ~R1 = H, R2 = ~H3 andlor Ra z ~3,Rg = H) and the aromatic radical or radicals represent the cumyl structure (R3 - R4 = C~3 andlor ~s = X
CH3~.
lhe preparation may be carried out in the usual manner by reactlng a t-alcohol with hydrogen peroxide in an acid medium to ~orm the corresponding t-alkylhydroperoxide and converting the resulting compound with a t-alcohol, also in an acid medium, into the peroxide; at least one of the two t-alcohols used should be unsaturated.
Examples of saturated t-alcohols to be used in the preparation o-E the present peroxides include t-butyl alcohol, t-a~yl alcohol, 2-hydroxy-2-methylpentane, cumyl alcohol (=~-hydroxyisopropylbenzene), 1,3-bis(~-hydroxyisopropyl)benzene, 1,4-bis(~-hydroxyi~opropyl)benzene and 1,3,5-tris-(~-hydroxyisopropyl)benzene.
Examples of unsaturated t-alcohols to be used in the preparation of the present peroxides include l-~-hydroxyisopropyl)-3-isopropenylbenzene, 1-(~-hydroxyisopropyl)-4-isopropenylbenzene, 1-~-hydroxyisopropyl)-3,5-bis-(isopropenyl)benzene, 1,3-bis(~-hydroxyisopropyl)-5~isopropenyIb~nzene and ~ hydroxyisopropyl)-2,4-bl9(isopropenyl)benæene. Preparation of the~e unsaturated t-alcohols may be carried out by partlal dehydration of the corresponding diols or triols in the manner described in US 3 622 636 for the preparation of 1-(~-hydroxyisopropyl)-3-isopropenylbenzene and 1-(~-hydroxyisopropyl)-4-isopropenylbenzene from, respectively, 1,3-bis(~-hydroxyisopropyl~benzene and 1,4-bis(~-hydroxyisopropyl)benzene, Examples of suitable peroxides where in the general ~ormula I m~O are:
1-(cumyl peroxy isopropyl)-3-isopropenyIbenzene and 1-(cumyl peroxy isopropyl)-4-i~opropenylbenzene.
Examples of suitable peroxides where in the general Formula m~O are:
l-(t-butyl peroxy isopropyl)-3-isopropenylbenzene, 1-(t-butyl peroxy isopropyl)-4-isopropenyIbenzene, 1,3-di(t-amyl peroxy isopropyl)-5-isopropenylbenzene, 1-(t-butyl peroxy isopropyl)-3,5-bis(isopropenyl~benzene, 1-(t-butyl peroxy isopropyl)-2,4-bis(isopropenyl)benzene and 1,3-di(t-butyl peroxy isopropyl)-5-isopropenyIbenzene.
~articularly suitable for use in the process according to the invsntion are those peroxides where m has the value of 1 and, when R7 represents the group A, p also has the value of 1. More particularly preferred are those peroxides where R1 = H, Rz = R3 = Rl, = Rs = R~ = a methyl group and, when ~ X7 represents a group A, Rg = a methyl group and Rg s H.
; The present peroxides also may be used in combination with each other.As regards the structure of the present peroxides it should still be noted that steric requirements lead to the aromatic substituents not being ortho to each other in the case of disubstitution and to their not being in three adjacent positions in the case of trisubstitution . The invention will be further described in the following examples.
Example 1 Preparation of 1-(t-butyl peroxy isopropyl)-3-isopropenylbenzene (Com-pound 1) To a mixture of equimolar amounts of t-butyl hydroperoxide ~32 g~ and 1-(~-hydroxyisopropyl)-3-isopropenylbenzene (57 g) stirred at 30VC ~here were added 1,32 ml of an aqueous solution of 20% by weight of perchloric acid.
Over a period of 30 minutes MgSO4.2H20 was added portionwise up to an amount of in all 26,3 g, after which the rea~tion mixture was stirred for 2 hours at 35~C. Then quf~icient water was added to dissolve all oE the ~:2715i~
magnesium sulphate. 'rhe or~anic phase was separated, washed with aqueous NaO~ and finally with water. Obtained were 80 g of a colourless liquld (yield 90~/0) having an active oxygen content of 6~02V/o (calc. 6,44~/o). 'rhe structure was confirmed by NMR and IR analyses.
Example 2 Preparation of 1-~t-butyl peroxy isopropyl)-4-isopropenYlbenzene ~Com~
pound 2) The same procedure was carried out as described in Example 1, except that use was made of equimolar amounts of 1-(a-hydroxyisopropyl)-4-isopropenyl-benzene and t-butyl hydroperoxide. Obtained wa~ a colourless liquld ~yield 90~/0) having an active oxygen content of 5~58U/o (calc. 6~44~/o~ lrhe structurewas conflrmed by NMR and IR analyses.
Example 3 Preparation of Compound 3 'fhe same procedure was carriad out as described in Example 1, except that use was made of equimolar amounts of 1-(~-hydroxylsopropyl)-3-isopropenyl-benzene and l-(a-hydroperoxyisopropyl)-3-isopropenylbenzene. Obtained was a colourless liquid (yield 70~tO) having an active oxygen content of 3,81~/~
(calc. 4~56~/o). lrhe structure was confirmed by ~MR and IX analyses.
ExamPle 4 Preparation of Compound 4 The same procedure was employed as described in Example 1, sxcept that use was made of equimolar amounts of 1-(~-hydroxyisopropyl)-4-isopropenyl-benzene and l-(a-hydroperoxyisopropyl~-4-isopropenyIbenzene. Obtained was a viscous liquid from which the product was isolated as white crystals by crystallization with diethyl ether. 'rhe product was obtained in a yield of 60uto and had a melting point of 82V-85~C and an active oxygen content of 4~20~o (calc. 4t56~to). ~'he structure was characterized by NMR and rR
analyses.
Example 5 Preparation of l-(cumyl peroxy isopropyl)-4-isopropenyIbenzene (Com-pound 5) The same procedure was used as described in Example 4, except that use was made of equimolar amounts of 1-(~-hydroxyisopropyl)-4-isopropenylbenzene and cumyl hydroperoxide. Obtained were white crystals (yield 70æ) having a melting point of 40VC and an active oxygen content of 4,34% (calc. 5,15). a The structure was confirmed by NMR and IR analyses.
Example 6 Preparation of 1,3-di(t-butYl peroxy i30propyl)-S-isopropenyl~enzene (Com-pound 6) To a mixture of 1,3-bis(a-hydroxyisopropyl)-5-isopropenylbenzene ~14 g), t-butyl hydroperoxide (lS g) and hexane~50 ml) stirred at 35VC there were added 0,55 ml of an aqueous solution of 20V/o by weight of perchloric acid and subsequently ~gS04.2B20 (10,6 g), the latter in a portionwise manner, after which the reaction mixture was stirred for 3 hours at 40~C. Then suf-ficient water was added to dissolve all of the magnesium sulphate. rhe organic phase was separated, washed with aqueous NaOH and finally with water. After removal of the hexane from the organic phase under reduced pressure, 22 g of a yellow oil were obtained (yield 9S~/O) having an active ; ~ oxygen content of 8,29% (calc. 8~47U/o). 'rhe structure was confirmed by NMR
and IR analyses.
Example 7 Preparation of l-(t-butyl peroxy isopropyl~-3~5-bis~isopropenyllbenzene ~CoMPound 7) The same procedure was employed as described in Example I, sxcept that use was made of equimolar amounts of 1-(~-hydroxyisopropyl~-3,5-bis(iso-propenyl)benzene and t-butyl hydroperoxide. Obtained was a yellow liquid (yield 95~h) having an active oxygen content of 5,12~ (-calc. 5~56~/o). 'rha structure was confirmed by NMR and IR analyses.
~8~ 7~L~3~
Example 8 ! f the peroxides described in the preceding examples the permissible processing temperature was determined as follow~.
~ver a period of 5 minutes 0,OI equivalent of the peroxide was mixed with 100 g of ethylene-propylene copolymer (E~? on a roll mill at a friction of 1:1,2 and at a temperatu}e of 50~-70VC. Of the resulting mixture the cross-linking behaviour was subsequsntly determined with the aid of a ~'ottfert Elastograph in the manner described in Kautschuk und Gummi Z9(5/6) 341-35Z
(1976). In this determination the mixture to be cross-linked i9 embedded in a heated chamber the lower half of which is oscillatory. During cross-linking the increase is registered in the torque on the lower chamber half as a result of the increase in viscosity of the cross-linking mixture as a function of time. '~he increase in torque is expressed in the parameters t1o and tgo which represent the time necessary under the given conditions to bring about respectively lOU/o and 90~/~ of the increase in torque (~torque).
The determinations were carried out at 170~C, using being made of a slit width of 0,2 mm, an oscillation angle of about 0,S~ and an oscillation frequency of 0,83 Hz. The results are given in l'able 1. For comparison also the values are mentioned of analogous experiments carried out using 0,01 mole of dicumyl peroxide tCompound A) and 0,01 mole of 1-phenyl-3,3-di(t-butylperoxy)-1-propene (Compound B: an unsaturated peroxide according to US 3 9gO 629).
From the t1o and tgo values found it appears that the processing range of the present peroxides is similar to that of dicumyl peroxide (A) and in several cases even exceeds it, whereas the processing range of the peroxide (B) disclosed in US 3 980 629 i9 narrower.
Table 1 _ _ Compound tlo (min) tgO (min) 0,6 5 6 0,8 7 7 0,9 8 j A L 0'7 7 Example 9 l'he peroxides described in Examples l and 6 were tested as cross-linking agent for polyethylene. To that end 0,01 equivalent of each peroxide was mixed on a roll mill for 3 minutes at 120~-130VC with 100 g of low-density polyethylene ~Lupolen~ 1810 H, ex BAS~`).
l'he cross-linking behaviour was determined with the aid o~ the ~ottfert Elastograph described in Example 8. The t1o, tg~ and ~torque values ob-tained are listed in Table 2. The Table also gives the compression moulding temperature and the compression moulding time applied in the cross-llnking processes.
The cross-linked products obtained were tested for odour and bloomlng and the following propertie6 were measured.
- l'he tensile strength, the lO0, 200 and 300~/0 moduli and the elongation at break were determined in accordance with IS0-standard ~37 type l.
- The hardness was determined in accordance with ASTM D2240.
- 'rhe gel fraction was measured in conformity with the standards B5 5468-lg77 and A~IIASTM ~2765-68(1972~. In this test the percentage polymer is determined which does not dissolve in boiling xylene under the test conditions. l'his parameter is a measure of the degree of cross-linking and hence of the efficiency of the peroxide.
The results are given in Table 2. It also mentions the results of a com-parative experiment carried out wlth 0,01 mole of dicumyl pe~oxide (Com-pound A).
The results obtained show that the peroxides according to the invention are a good alternative to dicumyl peroxide. Furthermore the remarkably high value o ~torque obtained with Compound 6 should be noted. l~his high value is surprising in view of the fact that Compounds l, 6 and A were used in equivalent amounts (i.e. 0,01 mole of Compounds l and A and 0,005 mole of Compound 6).
~:71585 Table 2 Compound 1 6 A
_ . .
t1o (min) 1,2 1,3 lt1 tgo ~min) 8,2 8,7 8,8 ~torque (~m) 0,51 0,67 0,48 Compression moulding temp. ~C) 180 18~ 170 Compression moulding time ~min) 20 20 20 Tensile strength (~Pa) 21,5 19,7 19,7 ~odulus 100~/~ (MPa) 7,6 8,1 7,8 Modulus 200~/o (MPa) 7,9 8,6 8,2 Modulus 300~b ~Pa) 9,7 12,5 10,3 ~long. at break (V/o~ 450 360 420 Hardness ~Shore D ~9 45 49 Gel fraction (J/O) 86 88 90 Odour none none yes ~looming after 1 week none none yes To further demonstrate that the peroxides according to the invention have desirable properties as regards their decomposition products the following experiments were carried out.
Samples of the cross-linked products obtained in Example 9 were exhaustively extracted with dichloromethane at reflux temperature.
Gaschromatographic analysis of the resulting solutions showed that no aromatic compounds were present in the solutions from the products prepared with Compounds 1 and ~ whereas in the solution from the product prepared wi~h dicumyl peroxide (Compound A) acetophenone and cumyl alcohol could be clearly identified.
In another set of experiments the cross-linking reactions described in Example 9 were repeated, except that in stead of the ~-ottfert Elastograph use was made of a closed reactlon vessel coupled to a gas chromatograph ~ (head space gas chromatography). At regular time intervals gas samples from the reaction vessel were analyzed for aromatic decomposition products. In the case of Compounds 1 and 6 no aromatic decomposition products could be detected wherea~ in the case of dicumyl peroxide (Compound A) acetophenone and cumyl alcohol could be clearly identified.
Example 10 ~'he peroxide described in Example 1 was tested as degradant for polypropylene. 'rhe following procedure was used.
Unstabilized polypropylene (Moplen~ FLS 20, ex. Himont; melt ~low index (230~C, 2,1~ kg): 1,8 g/10 min) was mixed with the peroxide in a tumble mixer. The resulting product was processed through a single ~crew extruder at elevated temperature. After cooling to room temperature, the extrudate was granulated and of the resulting granules the melt flow index was determined.
The amounts of peroxide used, the extrusion temperatures applied and the melt flow indices obtained are listed in Table 3. From the indices obtained it appears that the peroxlde according to the invention Is a suitable poly-propylene degradant. ln addition to this it was observed that the extrudate obtained was odourles~ whereas in a comparative experiment carried out with dicumyl peroxide as degradant an unpleasantly smelling extrudate resulted.
Table 3 Amount of peroxide Extrusion temp. Melt flow index (wt.~to) ( C) (gl10 min) 0,0171 200 5,7 (1) 0,0171 250 8,2 11) 0,0855 200 28,1 (1) 0,0855 250 35,1 (1) 0,428 200 84,8 (2) 0,428 250 209 (2) _ (1) Measuring conditions: 230~C12,16 kg
(2) Measuring conditions: l90~C~2,16 kg
Claims (5)
1. A process for cross-linking or degrading polymers, use being made of an organic peroxide which has at least one carbon-carbon double bond in the molecule, characterized in that the peroxide corresponds to the general structural formula.
(I) where m = 0,1 or 2;
n = 1,2 or 3;
m+n = < 3;
R1 = H or an alkyl group containing 1-3 carbon atoms;
X2 = an alkyl group containing 1-4 carbon atoms;
R3-R6= alkyl groups containing 1-10 carbon atoms;
R7 = an alkyl group containing 1-10 carbon atoms which is sub-stituted or not with a C1-10 alkoxy group, a C1-C10 acetoxy group or a hydroxyl group, or represents a group A of the general formula where p = 1 or 2 and R8 and R9 have the meaning indicated above for R2 and X1, respectively;
with the proviso that in the case of disubstitution the aromatic ring sub-stituents are not ortho to each other and in the case of trisubstitution are not in three adjacent positions, and that when m=0, R7 represents a group A.
(I) where m = 0,1 or 2;
n = 1,2 or 3;
m+n = < 3;
R1 = H or an alkyl group containing 1-3 carbon atoms;
X2 = an alkyl group containing 1-4 carbon atoms;
R3-R6= alkyl groups containing 1-10 carbon atoms;
R7 = an alkyl group containing 1-10 carbon atoms which is sub-stituted or not with a C1-10 alkoxy group, a C1-C10 acetoxy group or a hydroxyl group, or represents a group A of the general formula where p = 1 or 2 and R8 and R9 have the meaning indicated above for R2 and X1, respectively;
with the proviso that in the case of disubstitution the aromatic ring sub-stituents are not ortho to each other and in the case of trisubstitution are not in three adjacent positions, and that when m=0, R7 represents a group A.
2. A process according to claim 1, characterized in that the peroxide corresponds to the general structural formula I, where m=1 and, when R7 is a group A, p=1.
3. A process according to claim 2, characterized in that the peroxide corresponds to the general structural formula I, where R1 = H, R2 = R3 = R4 = R5 = R6 = a methyl group and, when R7 is a group A, R8 = a methyl group and R8 = a methyl group and R9 = H.
4. A process according to claim 1, 2 or 3, characterized in that a (co)polymer of ethylene is cross-linked or a polymer of propylene is degraded.
5. Shaped articles entirely or substantially consisting of (co)polymers obtained by any one of the processes according to claims 1-3.
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| US2340110A (en) * | 1942-07-03 | 1944-01-25 | Gen Electric | Process for removing cations from liquid media |
| US2511695A (en) * | 1945-12-08 | 1950-06-13 | Ellis Foster Co | Copolymer liquid polish |
| US2608549A (en) * | 1950-04-25 | 1952-08-26 | Goodrich Co B F | Interpolymers of vinyl chloride, higher alkyl acrylate and dialkenyl ester of olefinic dicarboxylic acid |
| US2810716A (en) * | 1954-06-28 | 1957-10-22 | White Lab Inc | Batchwise copolymerization technique |
| NL95727C (en) * | 1956-04-09 | |||
| NL241315A (en) * | 1958-07-18 | |||
| DE1643971C3 (en) * | 1967-07-13 | 1975-04-10 | Bayer Ag, 5090 Leverkusen | m- and p-isopropenylphenyl-dimethylcarbinol and processes for their preparation |
| US3980629A (en) * | 1969-07-29 | 1976-09-14 | The B. F. Goodrich Company | Organic peroxides derived from unsaturated compounds |
| SU757529A1 (en) * | 1978-06-08 | 1980-08-23 | Lvovskij Polt Inst | Alkyl(aralkyl)peroxyisopropylisopropenylbenzenes as peroxide monomers |
| US4255306A (en) * | 1978-09-15 | 1981-03-10 | The Dow Chemical Company | Vinylidene chloride polymer microgels |
| WO1980002285A1 (en) * | 1979-04-13 | 1980-10-30 | Politekhn I | Method of obtaining 1-methacrylate-1-tertiobutylperoxyethane |
| SU887578A1 (en) * | 1980-03-10 | 1981-12-07 | Львовский Ордена Ленина Политехнический Институт | Linear statistical copolymers of 1-tert-butylperoxyisopropyl-4-isopropenylbenzene and styrene as macroinitiators of grafted polymerization |
| JPS6017404B2 (en) * | 1980-12-15 | 1985-05-02 | ホ−ヤ株式会社 | Low dispersion high refractive index lens |
| JPS6011349A (en) * | 1983-07-01 | 1985-01-21 | 昭和電工株式会社 | Laminate as molded shape of polyurethane foam and olefin group polymer mixture |
| JPS6013828A (en) * | 1983-07-04 | 1985-01-24 | Showa Denko Kk | Olefinic polymer mixture |
| JPS6019762A (en) * | 1983-07-14 | 1985-01-31 | Nippon Oil & Fats Co Ltd | Production of peroxide having polymerizable unsaturated group |
| JPH0613828A (en) * | 1992-06-29 | 1994-01-21 | Nec Corp | Prodduction of surface acoustic wave element |
| JPH0619762A (en) * | 1992-07-01 | 1994-01-28 | Nec Corp | Data record reconstitution editing and outputting system |
| JPH0686176A (en) * | 1992-09-03 | 1994-03-25 | Matsushita Electric Ind Co Ltd | Driving method for solid-state image pickup device |
-
1986
- 1986-06-02 US US06/869,246 patent/US4774293A/en not_active Expired - Fee Related
- 1986-06-10 EP EP86201000A patent/EP0208353B1/en not_active Expired - Lifetime
- 1986-06-10 DE DE8686201000T patent/DE3676573D1/en not_active Expired - Fee Related
- 1986-06-10 AT AT86201000T patent/ATE59399T1/en not_active IP Right Cessation
- 1986-06-23 CA CA000512236A patent/CA1271585A/en not_active Expired - Fee Related
- 1986-06-25 ES ES556641A patent/ES8802173A1/en not_active Expired
- 1986-06-26 JP JP61148355A patent/JPS621733A/en active Pending
-
1988
- 1988-03-28 US US07/174,391 patent/US4833209A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| ES8802173A1 (en) | 1988-04-01 |
| EP0208353A1 (en) | 1987-01-14 |
| US4833209A (en) | 1989-05-23 |
| US4774293A (en) | 1988-09-27 |
| DE3676573D1 (en) | 1991-02-07 |
| JPS621733A (en) | 1987-01-07 |
| ATE59399T1 (en) | 1991-01-15 |
| EP0208353B1 (en) | 1990-12-27 |
| ES556641A0 (en) | 1988-04-01 |
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