Classifications

• • 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
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/34—Heterocyclic compounds having nitrogen in the ring
  • C08K5/3467—Heterocyclic compounds having nitrogen in the ring having more than two nitrogen atoms in the ring
  • C08K5/3477—Six-membered rings
  • C08K5/3492—Triazines
  • C08K5/34926—Triazines also containing heterocyclic groups other than triazine groups

Definitions

• the present invention relates to the use of low molecular weight triazine based compounds for increasing the resistance of polymers against degradation caused by heat and light; to polymer compositions with increased resistance to heat and light and to the use of such polymer compositions for producing articles.
• Such aging processes are normally based on oxidation reactions which are caused by heat, light, mechanical stress, catalysis or reactions with impurities.
• the aging of polymeric materials can occur during their production, during processing into shaped parts by moulding, extrusion, etc. and/or during use of the shaped parts.
• stabilizers such as antioxidants, light stabilizers and heat / thermal stabilizers can prevent or at least reduce these effects by adding them to the polymers to protect them during processing and to achieve the desired end-use properties.
• Antioxidants interrupt the degradation process in different ways, depending on their structure.
• the two major classifications are chain terminating primary antioxidants and hydroperoxide decomposing secondary antioxidants.
• Primary antioxidants react rapidly with peroxy radicals and are therefore called “radical scavengers”.
• the majority of primary antioxidants for polyolefins are sterically hindered phenols.
• Triazine based Mannich compounds have also shown to protect polyolefins against oxidative degradation and degradation caused by UV radiation (WO 2013/041592 A1 ). In contrast, phenolic compounds do not function well as light stabilizers.
• the heat stabilizing effect of a compound is strongly influenced by the temperature the polymer is exposed to and the protection mechanism.
• the polymer degradation at high temperatures is mainly due to the oxidation of the polymer itself, while at low temperatures the secondary oxidation of (smaller) oxidation products such as aldehydes is more important.
• Hindered amine light stabilizers are chemical compounds containing an amine functional group that are used as stabilizers in plastics and polymers. HALS do not absorb UV radiation, but act to inhibit degradation of the polymer by continuously and cyclically removing free radicals that are produced by photo-oxidation of the polymer. Broadly, HALS react with the initial polymer peroxy radical (ROO) and alkyl polymer radicals (R ⁇ ) formed by the reaction of the polymer and oxygen, preventing further radical oxidation. By these reactions HALS are oxidised to their corresponding aminoxyl radicals (R 2 NO c.f. TEMPO), however they are able to return to their initial amine form via a series of additional radical reactions. HALS's high efficiency and longevity are due to this cyclic process wherein the HALS are regenerated rather than consumed during the stabilization process.
• ROO initial polymer peroxy radical
• R ⁇ alkyl polymer radicals
• HALS are capable of preventing the oxidation of aldehydes, but do not influence the oxidation rate of polymers (hydrocarbons). Thus, HALS are known as good heat stabilizers at low temperatures (P. Gijsman, Polymer Degradation and Stability, 1994, 43: 171 -176).
• HALS Compared to the phenolic antioxidants the main benefit of HALS when used as thermal stabilizers are 1 ) high efficiency up to certain temperatures; 2) no or low discoloring. In particular the low discoloring provides the unique opportunity of HALS for some applications, such as low (no) gas fading fibre, or medical devices where specific sterilization technique are used (e.g. gamma radiation).
• the key limitation is the application temperature of HALS stabilized compounds. In most cases, HALS has an effective thermal stabilizing effect upto a temperature of about Q ' ⁇ . Beyond that temperature the efficiency drops significantly and conventional HALS are not suitable for applications above I dO ' ⁇ anymore.
• the present invention relates to the use of a triazine based compound of the general formula (I) wherein
• R 1 is hydrogen, halogen, substituted or non-substituted hydroxy, substituted or non- substituted amino, substituted or non-substituted C5-C20 aryl, substituted or non-substituted, linear or branched Ci-Ci 2 -alkyl, substituted and non-substituted, linear or branched C2-C12- alkenyl, wherein Ci-Ci 2 -alkyl and C 2 -Ci 2 -alkenyl can be interrupted by one or more atoms or groups selected from oxygen atoms, substituted or mono-substituted nitrogen atoms, double bonds, siloxan groups and/or by one or more groups of the type -C(0)0-, -OC(O)-, -C(O)-, - C(0)NH-,-NHC(0)0-, -0C(0)NH-, -NHC(0)NH- and/or -00(0)0-, whereby the atoms and groups selected from oxygen atom
• R 2 and R 3 are substituted and/or non-substituted C 3 -Cio-cycloalkyl, which comprises at least one nitrogen atom in the ring structure; as thermal stabilizer and/or light stabilizer in polyolefins at temperatures at or above
• a low molecular weight compound in particular with a molecular weight ⁇ 2000, preferably ⁇ 1800, more preferably ⁇ 1500, most preferably ⁇ 1200, is provided that can be used as light stabilizer, but in particular as thermal and/or light stabilizer in thermoplastic polymers at temperatures above I dO ' ⁇ .
• the triazine based compound show an improved stability effect at temperatures above 150 ' ⁇ when compared to conventionally used stabilizers such as 1 ,3,5-T ris(3’,5’-di-tert. butyl-4’-hydroxybenzyl)-isocyanurate (Irganox 31 14).
• Thermal and light stabilizing effects in particular at temperatures above I dO ' ⁇ , can also be described as overlapping effects.
• the HALS of the present invention may also be described as having light stabilizing effects at different temperatures, in particular above I dO ' ⁇ .
• the HALS compounds of the present invention protect the polyolefin against thermo oxidative degradation.
• the triazine based compound used in this invention have been described previously.
• DE 2319816 A1 discloses a family of triazine based HALS compounds used a light stabilizers in polymers. However, the use of such a triazine based compound as thermal stabilizer in polyolefins at elevated temperatures above I dO' ⁇ is not described.
• the triazine based compound of the invention has been used either as reactive substances, to create the high molecular weight HALS or with other polymers such as polyamid to form stabilized compositions. So far, no direct use of the triazine based molecules as thermal stabilizer in polyolefins is described.
• R 1 is hydrogen, halogen, substituted or non-substituted hydroxy, substituted or non-substituted amino, substituted or non-substituted C 1 -C 5 alkyl, substituted or non-substituted C 6 -Ci 2 aryl; and the moieties R 2 and R 3 are substituted and/or non-substituted C3-C 7 -cycloalkyl, which comprises at least one nitrogen atom in the ring structure.
• the moiety R 1 is from a group consisting of halogen, - OCH 3 , -OC 2 H 5 , substituted or non-substituted amino, methyl and phenyl.
• the moiety R 1 is halogen, such as chlorine, fluorine or bromine, in particular chlorine, or a primary amino group.
• the moieties R 2 and R 3 are substituted and/or non-substituted C 3 -C 7 - cycloalkyl, which comprises one or two nitrogen atoms in the ring structure.
• the triazine based compound of the general formula (I) comprises the following structure (II)
• R 4 and R 5 are selected independently from each other from substituted or non- substituted, linear or branched CrCis-alkyl, preferably substituted or non-substituted, linear or branched Ci-Cio-alkyl, and
• - n is 0 to 8, preferably 2-4.
• triazine based compound of the general formula (I) comprises the following structure (III)
• R 4a d and R 5a d are selected from substituted or non-substituted, linear or branched Cr C 5 -alkyl, preferably substituted or non-substituted, linear or branched C1-C3 alkyl.
• triazine based compound of the general formula (I) comprises the following structure (IV)
• R 1 has one the above meanings
• substituted in connection to aryl, alkyl, alkenyl and cycloalkyl relates to the substitution of one or more atoms, usually H-atoms, by one or more of the following substituents: halogen, hydroxy, protected hydroxy, oxo, protected oxo, C 3 -C 7 -cycloalkyl, phenyl, naphtyl, amino, protected amino, primary or secondary amino, heterocyclic ring, imidazolyl, indolyl, pyrrolidinyl, Ci-Ci 2 -alkoxy, Ci-Ci 2 -acyl, CrCi 2 -acyloxy, nitro, carboxy, carbamoyl, carboxamid, N-(Ci-Ci 2 -alkyl)carboxamid, N,N-Di(Ci-Ci 2 -alkyl)carboxamid, cyano, methylsulfonylamino, thiol
• substituted in connection to hydroxy and amino relates to the substitution of at least one H atom by one or in case of amino one or two of one of the substituents mentioned above, in particular substituted and non-substituted, linear or branched Ci-Ci 2 -alkyl, substituted and non-substituted C 3 -C 7 -cycloalkyl and substituted and non-substituted, linear or branched C 2 - Ci 2 -alkenyl.
• the hydroxy group can be present as an ether group.
• Amino group can be present as a primary or secondary amine.
• the term “suitalkyl“ relates to moieties like methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s- butyl, t-butyl, amyl, t-amyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, and alike.
• Preferred alkyl groups are methyl, ethyl, isobutyl, s-butyl, t-butyl und isopropyl.
• oxo relates to a carbon atom, which is connected with an oxygen atom via a double bond whereby a keto or an aldehyde group is formed.
• protected oxo relates to a carbon atom, which is substituted by two alkoxy groups or is connected twice with a substituted diol forming a non-cyclic or cyclic ketal group.
• the term relates to moieties like methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t- butoxy and alike.
• a preferred alkoxy group is methoxy.
• Thus comprises groups like cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl und cycloheptyl.
• the preparation of the triazine based compound suitable as stabilizer can be done for example by reacting cyanuric chloride with 4-Amino-2,2,6,6-tetramethylpiperidine 6-Chloro-A/ 2 ,A/ 4 - bis(2,2,6,6-tetramethylpiperidin-4-yl)-1 ,3,5-triazin-2,4-diamin (C 21 H 38 CIN 7, 1 ), which may react further to A ⁇ ,A/ 4 -(2,2,6,6-tetramethylpiperidin-4-yl)-1 ,3,5-triazin-2,4,6-triamin (2).
• the triazine based compound is used as thermal stabilizer and/or light stabilizer in polyolefins in a temperature range between 150‘O and 250 °C, preferably between I dO' ⁇ and 200‘O, more preferably between I QO' ⁇ and 180°C.
• the triazine based compound is added to the thermoplastic polymer in a concentration between 200 and 5000 ppm, preferably between 500 and 3000 ppm, more preferably between 1000 and 2000 ppm.
• concentration range is between 350 - 2500 ppm.
• polyolefins to be stabilized are for example:
• polymers of monoolefins and diolefins for example polypropylene, polyisobutylene, polybut- 1 -ene, poly-4-methylpent-1 -ene, polyisoprene or polybutadiene, as well as polymers of cycloolefins, for example of cyclopentene or norbornene; furthermore polyethylene (which optionally can be crosslinked); for example, high density polyethylene (HDPE), polyethylene of high density and high molar mass (HDPE-HMW), polyethylene of high density and ultrahigh molar mass (HDPE-UHMW), medium density polyethylene (HMDPE), low density polyethylene (LOPE), linear low density polyethylene (LLDPE), branched low density polyethylene (BLDPE).
• HDPE high density polyethylene
• HDPE-HMW polyethylene of high density and high molar mass
• HDPE-UHMW polyethylene of high density and ultrahigh molar mass
• HMDPE medium density polyethylene
• LOPE
• - Copolymers of monoolefins and diolefins with each other or with other vinyl monomers for example ethylene-propylene copolymers, linear low density polyethylene (LLDPE) and mixtures thereof with low density polyethylene (LDPE), propylene-but-1 -ene copolymers, propylene-isobutylene copolymers, ethylene-but-1 -ene copolymers, ethylene-hexene copolymers, ethylene-methylpentene copolymers, ethylene-heptene copolymers, ethylene- octene copolymers, propylene-butadiene copolymers, isobutylene-isoprene copolymers, ethylene-alkyl acrylate copolymers, ethylene-alkyl methacrylate copolymers, ethylene-vinyl acetate copolymers and their copolymers with carbon monoxide or ethylene-acrylic acid copolymers and their salts
• Polyolefins i.e. polymers of monoolefins exemplified in the preceding paragraphs, in particular polyethylene and polypropylene, can be prepared by various, and especially by the following, methods:
• metals usually have one or more ligands, such as oxides, halides, alcoholates, esters, ethers, amines, alkyls, alkenyls and/or aryls that may be either p- or s-coordinated.
• These metal complexes may be in the free form or fixed on substrates, for example on activated magnesium chloride, titanium(lll) chloride, alumina or silicon oxide.
• These catalysts may be soluble or insoluble in the polymerization medium.
• the catalysts can be active as such in the polymerization or further activators may be used, for example metal alkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metal alkyloxanes, the metals being elements of groups la, I la and/or Ilia of the Periodic Table.
• the activators may be modified, for example, with further ester, ether, amine or silyl ether groups.
• These catalyst systems are usually termed Phillips, Standard Oil Indiana, Ziegler-Natta, TNZ (DuPont), metallocene or single site catalysts (SSC).
• the polyolefin is selected from polyethylen, polypropylen, high pressure polyethylene or copolymers thereof.
• halogenated polyolefins in particular chlorinated polyeolefins, such as PVC
• chlorinated polyeolefins such as PVC
• hydrogen halides such as HCI
• additional compounds are added to the halogenated polyolefins which interact with the released hydrogen halides.
• organozinc compounds in particular organozinc compounds containing a Zn-0 or a Zn-S bond, such as Zn-stearate, are used for such purposes.
• non-halogenated polyolefins are preferably used.
• the polyolefins applied in the present case are free of any additional organometallic compounds that is not a catalyst or activator, in particular free of any organozinc compound.
• the present invention consequently, relates to a method of stabilizing a polyolefin against thermal and/or light degradation by incorporating an amount of a triazine based compound as defined above.
• the present invention also relates to a polymer composition
• a polymer composition comprising a polyolefin and a triazine based compound as defined above.
• the triazine based compound may be present in the polymer composition in a concentration between 200 and 5000 ppm, preferably between 500 and 3000 ppm, more preferably between 1000 and 2000 ppm. The most preferred concentration range is between 350 - 2500 ppm.
• the triazine based compounds of the formula (I) or mixtures therefrom of the present invention may be combined with a variety of additives conventionally employed in the antioxidant and/or UV stabilizing art, such as (further) anti oxidants, (further) UV absorbers and stabilizers, metal deactivators, antistatics, phosphites and phosphonites, hydroxylamines, nitrones, thiosynergists, co-stabilizers, nucleating agents, fillers and reinforcing agents, plasticizers, lubricants, emulsifiers, pigments, rheological additives, catalysts, level agents, optical brighteners, flameproofing agents, anti-static agents and blowing agents.
• additives are described in the "Plastics Additives Handbook".
• triazine based compounds useful as stabilizer according to the present invention optionally in combination with a further stabilizer or additive may be added to the polyolefin to be stabilized individually or mixed with one another. If desired, the individual components of such a stabilizer mixture can be mixed with one another in the melt (melt blending) before incorporation into the polyolefin to be stabilized.
• the incorporation of the triazine based compound of the invention and optional further components into the polyolefin is carried out by known methods such as dry blending in the form of a powder, or wet mixing in the form of solutions, dispersions or suspensions for example in an inert solvent, water or oil.
• the triazine based compounds of the invention and optional further additives may be incorporated, for example, before or after moulding or also by applying the dissolved or dispersed additive or additive mixture to the polymer material, with or without subsequent evaporation of the solvent or the suspension/dispersion agent. They may be added directly into the processing apparatus (e.g. extruders, internal mixers, etc), e.g. as a dry mixture or powder or as solution or dispersion or suspension or melt.
• the incorporation can be carried out in any heatable container equipped with a stirrer, e.g. in a closed apparatus such as a kneader, mixer or stirred vessel.
• a stirrer e.g. in a closed apparatus such as a kneader, mixer or stirred vessel.
• the incorporation is preferably carried out in an extruder or in a kneader. It is immaterial whether processing takes place in an inert atmosphere or in the presence of oxygen.
• the addition of the additive or additive blend to the polymer can be carried out in all customary mixing machines in which the polymer is melted and mixed with the additives. Suitable machines are known to those skilled in the art. They are predominantly mixers, kneaders and extruders.
• the process is preferably carried out in an extruder by introducing the additive during processing.
• Particularly preferred processing machines are single-screw extruders, contrarotating and corotating twinscrew extruders, planetary-gear extruders, ring extruders or cokneaders. It is also possible to use processing machines provided with at least one gas removal compartment to which a vacuum can be applied. Suitable extruders and kneaders are described, for example, in Handbuch der Kunststoffextrusion, Vol. 1 Kunststoffn, Editors F. Hensen, W. Knappe, H. Potente, 1989, pp. 3-7, ISBN:3-446-14339-4 (Vol.
• the screw length is 1 - 60 screw diameters, preferably 35-48 screw diameters.
• the rotational speed of the screw is preferably 10 - 600 rotations per minute (rpm), very particularly preferably 25 - 300 rpm.
• the maximum throughput is dependent on the screw diameter, the rotational speed and the driving force.
• the process of the present invention can also be carried out at a level lower than maximum throughput by varying the parameters mentioned or employing weighing machines delivering dosage amounts. If a plurality of components is added, these can be premixed or added individually.
• the triazine based compounds of the invention and optional further additives can also be added to the polymer in the form of a masterbatch ("concentrate") which contains the components in a concentration of, for example, about 1 % to about 40% and preferably 2 % to about 20 % by weight incorporated in a polymer.
• concentration a masterbatch
• the polymer need not be necessarily of identical structure than the polymer where the additives are added finally.
• the polymer can be used in the form of powder, granules, solutions, suspensions or in the form of latices.
• Incorporation can take place prior to or during the shaping operation, or by applying the dissolved or dispersed compound to the polymer, with or without subsequent evaporation of the solvent. In the case of elastomers, these can also be stabilized as latices.
• a further possibility for incorporating the additives of the invention into polymers is to add them before, during or directly after the polymerization of the corresponding monomers or prior to crosslinking. In this context the additive of the invention can be added as it is or else in encapsulated form (for example in waxes, oils or polymers).
• polymer compositions in particular the polyolefin compositions, containing the triazine based compounds of the invention described herein can be used for the production of mouldings, rotomoulded articles, injection moulded articles, blow moulded articles, pipes, films, tapes, mono-filaments, fibers, nonwovens, profiles, adhesives or putties, surface coatings and the like.
• the invention is explained in more detail in the following examples.
• Example 1 6-Chloro-A ⁇ ,A/ 4 -bis(2,2,6,6-tetramethylpiperidin-4-yl)-1 ,3,5-triazin-2,4-diamin (HALS 2)
• Cyanuric chloride reacts with 4-Amino-2,2,6,6-tetramethylpiperidine to 6-Chloro-A ⁇ ,A/ 4 - bis(2,2,6,6-tetramethylpiperidin-4-yl)-1 ,3,5-triazin-2,4-diamin (C 21 H 38 CIN 7 ), called HALS2, as shown in
• Example 2 A ⁇ ,A/ 4 -(2,2,6,6-tetramethylpiperidin-4-yl)-1 ,3,5-triazin-2,4,6-triamin (HALS 4)
• HALS2 reacts with ammonia to A ⁇ ,A/ 4 -(2,2,6,6-tetramethylpiperidin-4-yl)-1 ,3,5-triazin-2,4,6- triamin , called HALS4, as shown
• the oxidative induction time is the measured time in which the oxidation of a sample is inhibited by an existing antioxidant stabilizer system.
• the OIT is measured while the sample is kept constant at a certain temperature under an oxygen stream.
• the measurement is performed in a differential scanning calorimeter (DSC).
• DSC differential scanning calorimeter
• the sample and the reference are heated under constant nitrogen atmosphere to a specific temperature. When this temperature is reached, the gas flow switches to oxygen at the same flow rate. Until the oxidative degradation starts, the material is held at a constant temperature.
• the OIT is represented on a thermal curve. It is the time span between the start of the oxygen and the onset of the oxidative degradation reaction. The onset is indicated by a sudden change in heat flow.
• the OIT measurements are carried out according to ISO 1 1357-6 on a Mettler Toledo DSC822e. The measurements are done with open pans.
• Sample preparation 0.2 wt% active group equivalent are mixed into Squalane (SQ).
• Squalane is used as matrix material due to its chemical similarity to PP and the easier handling.
• the structure is shown in Scheme 3. The stabilizer and SQ are first mixed in an ultrasonic bath and then with stirring to afford a homogenous suspensions.
• the measurement is stopped when the degradation starts.
• the degradation is indicated with a sudden change in the heat flow curve indicating an exothermal process.
• the OIT-curves for HALS2 and HALS4 at 160 °C are shown in Table 1 .
• Tinuvin 770 Bis-(2,2,6,6-tetramethyl-4-piperidyl)-sebacate) and Irganox 31 14 (1 ,3,5-T ris(3’,5’- di-tert. butyl-4’-hydroxybenzyl)-isocyanurate) are used as comparative examples CE1 and CE2, respectively.
• Table 1 lists the OIT of Inventive Examples (lEs) and Comparative Examples (CEs). Surprisingly it was found that by proper design the molecules, the IE do not work only at low T (like I Od' ⁇ ), but also works at higher T (like 160°C), which is typically not the case of HALS and rather on the same level as phenolic antioxidants.

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• 2019
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