A POLYETHYLENE PIPE

A polyethylene pipe comprising components A) and B), wherein component A) is a hindered amine light stabilizer containing a triazine residue, component B) is a natural or synthetic hydrotalcite and the weight ratio of component A) to component B) is 1:10 to 10:1.

The present invention relates to a polyethylene pipe comprising components A) and B), wherein component A) is a hindered amine light stabilizer containing a triazine residue, component B) is a natural or synthetic hydrotalcite and the weight ratio of component A) to component B) is 1:10 to 10:1, preferably 1:5 to 5:1.

In more detail, the pipe according to the present invention preferably consists of a polyethylene composition comprising the components A) and B) in a weight ratio of 1:10 to 10:1.

Component A) is in particular at least one compound of the formula (A-I), (A-II) or (A-III)

the radicals A12independently of one another are hydrogen, C1-C12alkyl or C5-C12cycloalkyl,

A13and A14independently of one another are hydrogen, C1-C12alkyl, C5-C12cycloalkyl or a group of the formula (a-1),

or the radicals A13and A14, together with the nitrogen atom to which they are bonded, form a 5- to 10-membered heterocyclic ring and

a1is a number from 1 to 20, preferably 2 to 20, and the repeating units are identical or different;

wherein A21and A25independently of one another are hydrogen, C1-C12alkyl, C5-C12cycloalkyl or a group of the formula (a-1),

A22, A23and A24independently of one another are C2-C10alkylene, and

X1, X2, X3, X4, X5, X6, X7and X8 independently of one another are a group of the formula (a-2),

in which A26is hydrogen, C1-C12alkyl, C5-C12cycloalkyl or a group of the formula (a-1) as defined above, and A27has one of the meanings of A12;

wherein

R3and R4independently of one another are C1-C22alkyl or a group of the formula (a-3)

wherein R0has one of the meanings of R1and R2.

Component B) is preferably a mixed hydroxide of the formula (B-I) or (B-II).

a is for example a number up to 0.5.

b is for example an integer from 1 to 4.

c is for example zero or a number up to 2.

d is for example a number up to 6.

e is for example a number up to 2.

f is for example zero or a number up to 15.

Hydrotalcites which are of interest are layered double hydroxides that contain positively charged hydroxide layers and charge balancing anions located in the interlayer region.

Component B) is in particular at least one magnesium aluminum hydroxide carbonate hydrate which is for example commercially available as Hycite®713, ®DHT-4A, ®DHT-4V, ®DHT-4A-2, ®DHT-4C or Sorbacid®911, or zinc aluminum hydroxide carbonate hydrate which is for example commercially available as ®ZHT-4V or Sorbacid®944, or mixtures thereof.

Of particular interest is a magnesium aluminum hydroxide carbonate hydrate which is for example commercially available as Hycite®713 or DHT-4A.

C2-C18alkoxy substituted by —OH is for example 2-hydroxyethoxy.

C3-C6alkenyl is for example allyl, 2-methallyl, butenyl, pentenyl or hexenyl. Allyl is preferred. The carbon atom in position 1 is preferably saturated.

C3-C6alkenyloxy is for example propenyloxy.

C7-C9phenylalkyl unsubstituted or substituted on the phenyl by 1, 2 or 3 C1-C4alkyl is for example benzyl, 2-phenylethyl, methylbenzyl, dimethylbenzyl, trimethylbenzyl or tert-butylbenzyl.

An example of C5-C7cycloalkylene is cyclohexylene.

An example of C1-C4alkylenedi(C5-C7cycloalkylene) is methylenedicyclohexylene.

A preferred example of a 5-to 7-membered heterocyclic ring is a morpholine group.

The meanings of the terminal groups which saturate the free valences in the compounds of the formula (A-I) depend on the processes used for their preparation. The terminal groups can also be modified after the preparation of the compounds.

If the compounds of the formula (A-I) are prepared by reacting a compound of the formula

in which X0is, for example, halogen, in particular chlorine, and A13and A14are as defined above, with a compound of the formula

in which A11and A12are as defined above, the terminal group bonded to the diamino radical is for example hydrogen or

and the terminal group bonded to the triazine radical is for example X0or

If X0is halogen, it is advantageous to replace this, for example, by —OH or an amino group when the reaction is complete. Examples of amino groups which may be mentioned are pyrrolidin-1-yl, morpholino, —NH2, —N(C1-C8)alkyl)2and —NR0(C1-C8alkyl), in which R0is hydrogen or a group of the formula (Ia).

One of the preferred compounds of the formula (I) is

and a1is a number from 1 to 10, preferably 2 to 10. The preparation of this compound is described in Example 10 of U.S. Pat. No. 6,046,304.

According to a preferred embodiment

the radicals A12independently of one another are hydrogen, C1-C4alkyl or cyclohexyl,

A13and A14independently of one another are hydrogen, C1-C4alkyl, cyclohexyl or a group of the formula (a-1),

or the radicals A13and A14, together with the nitrogen atom to which they are bonded, form a morpholino group and

a1is a number from 1 to 10, preferably 2 to 10, and the repeating units are identical or different;

A21and A25independently of one another are hydrogen, C1-C4alkyl or cyclohexyl,

A22, A23and A24independently of one another are C2-C10alkylene, and

X1, X2, X3, X4, X5, X6, X7and X8independently of one another are a group of the formula (a-2),

in which A26is hydrogen, C1-C4alkyl, cyclohexyl or a group of the formula (a-1) as defined above, and A27has one of the meanings of A12;

R1and R2independently of one another are hydrogen, C1-C4alkyl or cyclohexyl; and

R3and R4independently of one another are C1-C4alkyl or a group of the formula (a-3)

wherein R0has one of the meanings of R1and R2.

According to a further preferred embodiment component A) is a compound of the formula (A-I-1), (A-I-2), (A-II-1) or (A-III-1),

The polyethylene pipe may additionally comprise a component C) which is a phenolic antioxidant, in particular 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene (Irganox®1330), ethylene bis[3,3-bis(3-tert-butyl-4-hydroxyphenyl)butyrate] (Hostanox®03) or 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-isocyanurate (Irganox®3114).

The weight ratio of component A) to component C) is preferably 1:10 to 10:1, in particular 1:5 to 5:1.

The polyethylene pipe may further comprise a component D) which is at least one compound selected from the group consisting of phosphites, phosphonites, hydroxylamines, tocopherols and tocopherol acetates. A phosphite, for example tris(2,4-di-tertbutylphenyl) phosphite, [3,3′,5,5′-tetra-tert.butyl-1,1′biphenyl-2,2′-diyl]-[3-(3-methyl-4-hydroxy-5-tert.butyl-phenyl)-propyl]-phosphite, [2,2′-ethylene-bis-(4,6-di-tert.butyl-phenyl)-1,1′-diyl]-[1,6-d imethyl-4-(5,7-di-tert.butyl)-3H-1-benzofuran-2-one)-phenyl]-phosphite, [2,2′-ethylene-bis-(4,6-di-tert.butyl-phenyl)-1,1′-diyl]-[1-methyl-6-tert.butyl-4-(5,7-di-tert.butyl)-3H-1-benzofuran-2-one)-phenyl]-phosphite or 6-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin, is particularly preferred.

The weight ratio of component A) to component D) is preferably 1:10 to 10:1, in particular 1:5 to 5:1.

Of interest is a polyethylene pipe which comprises components A), B), C) and D). The compounds of components A), B), C) and D) are known and are in essential commercially available.

Component A) is preferably present in the polyethylene in an amount of 0.01% to 2% by weight relative to the weight of the polyethylene.

Component B) is preferably present in the polyethylene in an amount of 0.01% to 5% by weight relative to the weight of the polyethylene.

Component C) is preferably present in the polyethylene in an amount of 0.1% to 5% by weight relative to the weight of the polyethylene.

Component D) is preferably present in the polyethylene in an amount of 0.1% to 5% by weight relative to the weight of the polyethylene.

According to a preferred embodiment the polyethylene pipe may additionally comprise a pigment, preferably a blue pigment.

A particularly preferred polyethylene pipe comprises the components (A), (B), (C) and (D), wherein component (A) is

component (B) is a natural or synthetic hydrotalcite,

component (C) is 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, and

The polyethylene of the pipe according to the present invention may further comprise one or more conventional additives such as:

1.11. Benzylphosphonates, for example dimethyl-2,5-di-tert-butyl-4-hydroxybenzylphosphonate, diethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, di-octadecyl3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate, the calcium salt of the monoethyl ester of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid.

2. UV Absorbers and Light Stabilizers

The following phosphites are especially preferred:

11. Nucleating agents, for example inorganic substances, such as talcum, metal oxides, such as titanium dioxide or magnesium oxide, phosphates, carbonates or sulfates of, preferably, alkaline earth metals; organic compounds, such as mono- or polycarboxylic acids and the salts thereof, e.g. 4-tert-butylbenzoic acid, adipic acid, diphenylacetic acid, sodium succinate or sodium benzoate; polymeric compounds, such as ionic copolymers (ionomers). Especially preferred are 1,3:2,4-bis(3′,4′-dimethylbenzylidene)sorbitol, 1,3:2,4-di(paramethyldibenzylidene)sorbitol, and 1,3:2,4-di(benzylidene)sorbitol. Beta-nucleating agents are also of interest.

12. Fillers and reinforcing agents, for example calcium carbonate, silicates, glass fibres, carbon fibers, glass beads, asbestos, talcum (preferably with a particle size of 0.01 to 20 μm), kaolin, mica, barium sulfate, metal oxides and hydroxides, carbon black, graphite, wood flour and flours or fibers of other natural products, synthetic fibers.

The conventional additive may be present in the polyethylene of the pipe according to the present invention in an amount of e.g. 0.001 to 10%, relative to the weight of the polyethylene.

A further embodiment of the present invention is the polyethylene pipe as defined above, which is in contact with chlorinated (common chlorinated water disinfectants such as chlorine (hypo-chlorite), chlorine dioxide and chloramines) or non-chlorinated water.

Another embodiment of the present invention is the use of a mixture containing components A) and B) in a weight ratio of 1:10 to 10:1 for stabilizing a polyethylene pipe.

Still another embodiment of the present invention is a method for stabilizing a polyethylene pipe which comprises incorporating into the polyethylene components A) and B) in a weight ratio of 1:10 to 10:1.

The embodiments of the present invention include chlorinated or non-chlorinated water pipes for domestic, municipal or industrial applications, non-pressure up to high-pressure pipe applications used for drinkable or non-drinkable water, for general purpose water or waste water.

The examples below illustrate the invention in greater detail. All percentages and parts are by weight, unless stated otherwise.

Additives used on the following examples:

Compound (108) Disclosed in Example S-8 of WO-A-2015/121445

and a1is a number from 2 to 10.

EXAMPLES

Preparation of the test specimens: A mixture of a non-stabilised high density polyethylene (HD-PE; Hostalen° CRP-100; natural classified under PE 100 of LyondellBasell; Melt Flow Rate: 190° C./5.0 Kg: 0.23 g/10 min (ISO 1133); Density: 0.95g/cm3 (ISO 1183)) and the additives listed in Table 1 is mixed with a Mixaco Lab CM12 high speed mixer device.

The obtained full formulation is then compounded on a Collin 25X42D extruder at 240° C. and then injection molded on an Engel HL65 injection molding machine at 230° C.

The injection molded plaques 40 mm×60 mm×2 mm are exposed to chlorinated water under the following parameters: 40° C., pH 7, 2 mg/L NaClO and 50 L/hours. The parameters measured are OIT Values using a DSC Q2000 von TA Instrument (Waters) at 200° C. under O2after 0, 3 and 5 months exposition. The depletion results are listed in Table 2.

High OIT-values are desired.