The invention relates to compositions for producing amino resin products and to products produced from them by melt processing. Processes for producing products from the compositions are further subject-matter of the invention.
Semi-finished products and shaped materials made from amino resins such as melamine-formaldehyde resins or melamine-urea-formaldehyde resins [Ullmann's Encyclopedia of Industrial Chemistry (1987), Vol. A2, 130-131] are known. A disadvantage associated with the production of products from melamine resins is the difficulty of their processing by common thermoplastic processing methods such as extrusion, injection moulding or blow moulding.
The melt viscosity of low molecular mass melamine resin precondensates is too low for these processing methods, and they can only be processed as highly filled moulding compounds with long cycle times and with curing of the products (Woebcken, W., Kunststoff-Handbuch Vol. 10 “Duroplaste”, Carl Hanser Verl. Munich 1988, pp. 266-274). Fibres, foams or coatings of melamine resins, owing to the low melt viscosity of the melamine resin precondensates, can be produced only starting from solutions of the melamine resin precondensates, with curing during the shaping operation.
Customary curing agents for amino resins are strong acids such as hydrochloric acid, sulphuric acid, p-toluenesulphonic acid and formic acid and also ammonium chloride (EP 0 657 496 A2; EP 0 523 485 A1, EP 0 799 260). A disadvantage with these curing agents is the inadequate cure rate in compositions with melamine resin precondensates having molar masses of 300 to 5 000 at short residence times during the melt processing of the compositions to semi-finished products and shaped materials, leading to unsatisfactory material properties.
The invention has as its object compositions of melamine resin precondensates and curing agents which are suitable for melt processing to amino resin products.
The object has been achieved by compositions for producing amino resin products by melt processing, the compositions being composed in accordance with the invention of
Examples of customary methods of melt processing are extrusion, injection moulding or blow moulding.
Examples of amino resin products which can be produced by melt processing are sheets, pipes, profiles, coatings, foam materials, fibres, injection mouldings and hollow articles.
The compositions for producing amino resin products can be in the form of cylindrical, lenticular, lozenge-shaped or spherical particles having an average diameter of 0.5 to 8 mm.
The polycondensates of melamine resins having molar masses of 300 to 300 000 can be polycondensates in which the triazine sequences are linked through bridge members —NH-alkylene-NH—.
Preferred melamine resins in the compositions of the invention are polycondensates of melamine and/or melamine derivatives and C1-C8 aldehydes with a melamine or melamine derivative/C1-C8 aldehyde molar ratio of 1:1.5 to 1:5 and also their partial etherification products, where the melamine derivatives can be melamines substituted by hydroxy-C1-C10-alkyl groups, hydroxy-C1-C4-alkyl-(oxa-C2-C4-alkyl)1-5 groups and/or by amino-C1-C12-alkyl groups, ammeline, ammelide, melem, melon, melam, benzoguanamine, acetoguanamine, tetramethoxymethylbenzoguanamine, caprinoguanamine and/or butyroguanamine, and the C1-C8 aldehydes are in particular formaldehyde, acetaldehyde, trimethylolacetaldehyde, acrolein, furfurol, glyoxal and/or glutaraldehyde, with particular preference formaldehyde.
The melamine resins may likewise contain 0.1 to 10% by mass, based on the sum of melamine and melamine derivatives, of incorporated phenols and/or urea. Suitable phenol components include phenol, C1-C9-alkylphenols, hydroxyphenols and/or bisphenols.
The precondensates of melamine resins having molar masses of 300 to 300 000 are preferably mixtures of meltable 4- to 1 000-nucleus oligotriazine ethers,
where in the polytriazine ethers the triazine segments
O—C5-C18-alkylene-NH— and/or —NH-C5-C18-alkylene-NH— to form 4- to 1 000-nucleus polytriazine ethers with a linear and/or branched structure, in the polytriazine ethers the molar ratio of the substituents R3:R4=20:1 to 1:20, the proportion of the linkages of the triazine segments through bridge members —NH—CHR3—O—R4—O—CHR3—NH— being from 5 to 95 mol %, and it being possible for the polytriazine ethers to contain up to 20% by mass of diols of the type HO—R4—OH.
The terminal triazine segments in the polytriazine ethers are triazine segments of the structure
The 4- to 1 000-nucleus polytriazine ethers used in the compositions of the invention can be prepared by etherifying melamine resin precondensates with C1-C4 alcohols, where appropriate with subsequent partial transetherification with C4-C18 alcohols, C2-C18 diols, polyhydric alcohols of the glycerol or pentaerythritol type, C5-C18 amino alcohols, polyalkylene glycols, polyesters containing terminal hydroxyl groups, siloxane polyesters, siloxane polyethers, melamine-alkylene oxide adducts and/or two-nucleus-phenol-alkylene oxide adducts and/or reaction with C5-C18 diamines and/or bisepoxides, and subsequent thermal condensation of the modified melamine resin condensates in the melt in a continuous compounder at temperatures of 140 to 220° C.
The melamine resin precondensates which are used in the preparation of the 4- to 1 000-nucleus oligotriazine ethers are preferably precondensates which as C1-C8 aldehyde components may comprise formaldehyde, acetaldehyde and/or trimethylolacetaldehyde and as melamine component may comprise not only melamine but also acetoguanamine and/or benzoguanamine. Particular preference is given to precondensates of melamine and formaldehyde with a melamine/formaldehyde molar ratio of 1:1.5 to 1:3.
The melamine resin polycondensates present in the compositions are preferably mixtures of meltable 4- to 300-nucleus polytriazine ethers.
The thermoinducible curing agents of the type of blocked sulphonic acid of the general formula
R1—SO2—O—R2 (I)
in the compositions for producing amino resin products are preferably blocked sulphonic acids in which the substituents
Examples of preferred blocked sulphonic acids are benzil monoxime tosylate, benzil monoxime p-dodecylbenzenesulphonate, 4-nitroacetophenone oxime tosylate, ethyl α-tosyloxyiminocaproate, ethyl α-cyclohexylsulphonyloxyiminophenylacetate, phenyl α-(4-chlorophenyl-sulphonyloxyimino)caproate, 4,4-dimethylbenzil monoxime tosylate, dibenzyl ketone oxime tosylate, acetone oxime p-benzoylbenzenesulphonate, α-tetralone oxime tosylate, anthraquinone monoxime tosylate, thioxanthone oxime tosylate, α-(p-toluenesulphonyloxyimino)benzyl cyanide, α-(4-nitrobenzenesulphonyloxyimino)benzyl cyanide, α-(benzenesulphonyloxyimino)-4-chlorobenzyl cyanide, α-(benzenesulphoxyimino)-2,6-dichlorobenzyl cyanide, α-(2-chlorobenzenesulphonyloxyimino)-4-methoxybenzyl cyanide, 4-chloro-α-trifluoroacetophenone oxime benzenesulphonate, fluorene oxime tosylate, α-(benzenesulphonyloxyimino)ureidocarbonylacetonitrile, α-(p-toluenesulphonyloxyimino)benzoylacetonitrile, 2,3-dihydro-1,4-naphthoquinone monoxime tosylate, acetophenone oxime tosylate, chroman oxime tosylate, 2-nitrobenzyl sulphonate, 2,6-dinitrobenzyl benzenesulphonate, 4-nitrobenzyl 9,10-dimethoxyanthracene-2-sulphonate, 2-methylsulphonyloxyimino-4-phenylbut-3-enenitrile, 4-cyclohex-1-enyl-2-methylsulphonyloxyiminobut-3-enenitrile, 4-furan-2-ylisopropylsulphonyloxyiminobut-3-enenitrile and 2-pentafluorophenylsulphonyloxyimino-4-phenylbut-3-enenitrile.
Examples of aliphatic C4-C18 carboxylic acids which may be present as thermoinducible curing agents in the formulations of the invention are butyric acid, caproic acid, palmitic acid, stearic acid and oleic acid.
Examples of aromatic C7-C18 carboxylic acids which may be present as thermoinducible curing agents in the formulations of the invention are benzoic acid, phthalic acid or naphthalenedicarboxylic acid.
Examples of alkali metal salts or ammonium salts of phosphoric acid which may be present as thermoinducible curing agents in the compositions of the invention are ammonium hydrogenphosphate, sodium polyphosphate and potassium hydrogenphosphate.
The C1-C12-alkyl esters and/or C2-C8-hydroxyalkyl esters of C7-C14 aromatic carboxylic acids in the compositions for producing amino resin products are preferably dibutyl phthalate, phthalic acid diglycol esters and/or trimellitic acid glycol esters.
In the compositions for producing amino resin products the salts of melamine and/or guanamines with C1-18 aliphatic carboxylic acids are preferably melamine formate, melamine citrate, melamine maleate, melamine fumarate and/or acetoguanamine butyrate.
In the compositions for producing amino resin products the anhydrides, monoesters or monoamides of C4-C20 dicarboxylic acids that are used as thermoinducible curing agents are preferably maleic anhydride, succinic anhydride, phthalic anhydride, mono-C1-C18-alkyl maleates, maleic monoamide or maleic mono-C1-C18-alkyl amides.
Examples of mono-C1-C18-alkyl maleates are monobutyl maleate, monoethylhexyl maleate or monostearyl maleate.
Examples of the maleic mono-C1-C18-alkyl amides are maleic monoethylamide, maleic monooctylamide or maleic monostearylamide.
In the compositions for producing amino resin products the monoesters or monoamides of copolymers of ethylenically unsaturated C4-C20 dicarboxylic anhydrides and ethylenically unsaturated monomers of the C2-C20 olefin and/or C8-C20 vinylaromatic type that are used as thermoinducible curing agents are preferably monoesters or monoamides of copolymers of maleic anhydride and C3-C8 α-olefins of the isobutene, diisobutene and/or 4-methylpentene and/or styrene type with a maleic anhydride/C3-C8 α-olefin and/or styrene and/or corresponding monomer mixtures molar ratio of 1:1 to 1:5.
In the compositions for producing amino resin products the salts of C1-C12-alkylamines and/or alkanolamines with C1-C8 aliphatic, C7-C12 aromatic and/or alkylaromatic carboxylic acids or inorganic acids of the hydrochloric acid, sulphuric acid or phosphoric acid type are preferably ethanolammonium chloride, triethylammonium maleate, diethanolammonium phosphate and/or isopropylammonium p-toluenesulphonate.
Examples of suitable fillers which may be present in the compositions for producing amino resin products at up to 400% by mass, based on the melamine resin precondensates, are Al2O3, Al(OH)3, barium sulphate, calcium carbonate, glass beads, siliceous earth, mica, quartz flour, slate flour, hollow microbeads, carbon black, talc, rock flour, wood flour, cellulose powders and/or husk meals and core meals such as peanut shell meal or olive kernel meal. Preferred fillers are phyllosilicates of the type of montmorillonite, bentonite, kaolinite, muscovite, hectorite, fluorohectorite, kanemite, revdite, grumantite, ilerite, saponite, beidelite, nontronite, stevensite, laponite, taneolite, vermiculite, halloysite, volkonskoite, magadite, rectorite, kenyaite, sauconite, boron fluorophlogopites and/or synthetic smectites.
Examples of suitable reinforcing fibres which may be present in the compositions for producing amino resin products at up to 400% by mass, based on the melamine resin precondensates, are inorganic fibres, especially glass fibres and/or carbon fibres, natural fibres, especially cellulosic fibres such as flax, jute, kenaf and wood fibres, and/or polymeric fibres, especially fibres of polyacrylonitrile, polyvinyl alcohol, polyvinyl acetate, polypropylene, polyesters and/or polyamides.
Examples of reactive polymers of the ethylene copolymer type which may be present in the compositions for producing amino resin products at up to 30% by mass, based on the melamine resin precondensates, are partially hydrolysed ethylene-vinyl acetate copolymers, ethylene-butyl acrylate-acrylic acid copolymers, ethylene-hydroxyethyl acrylate copolymers or ethylene-butyl acrylate-glycidyl methacrylate copolymers.
Examples of reactive polymers of the maleic anhydride copolymer type which may be present in the compositions for producing amino resin products at up to 30% by mass, based on the melamine resin precondensates, are C2-C20 olefin-maleic anhydride copolymers or copolymers of maleic anhydride and C8-C20 vinylaromatics.
Examples of the C2-C20 olefin components which may be present in the maleic anhydride copolymers are ethylene, propylene, but-1-ene, isobutene, diisobutene, hex-1-ene, oct-1-ene, hept-1-ene, pent-1-ene, 3-methylbut-1-ene, 4-methylpent-1-ene, methylethylpent-1-ene, ethylpent-1-ene, ethylhex-1-ene, octadec-1-ene and 5,6-dimethylnorbornene.
Examples of the C8-C20 vinylaromatic components which may be present in the maleic anhydride copolymers are styrene, α-methylstyrene, dimethylstyrene, isopropenylstyrene, p-methylstyrene and vinylbiphenyl.
The modified maleic anhydride copolymers present where appropriate in the compositions for producing amino resin products are preferably partly or fully esterified, amidated and/or imidated maleic anhydride copolymers.
Particularly suitable are modified copolymers of maleic anhydride and C2-C20 olefins and/or C8-C20 vinylaromatics having a molar ratio of 1:1 to 1:9 and molar mass weight averages of 5 000 to 500 000 which have been reacted with ammonia, C1-C18-monoalkylamines, C6-C18 aromatic monoamines, C2-C18 monoamino alcohols, monoaminated poly(C2-C4-alkylene) oxides with a molar mass of 400 to 3 000 and/or monoetherified poly(C2-C4-alkylene) oxides with a molar mass of 100 to 10 000, where the molar ratio of anhydride groups of copolymer/ammonia, amino groups of C1-C18-monoalkylamines, C8-C18 aromatic monoamines, C2-C18 monoamino alcohols and/or monoaminated poly(C2-C4-alkylene) oxide and/or hydroxyl groups of poly(C2-C4-alkylene)oxide is 1:1 to 20:1.
Examples of reactive polymers of the poly(meth)acrylate type which may be present in the compositions for producing amino resin products at up to 30% by mass, based on the melamine resin precondensates, are copolymers based on functional unsaturated (meth)acrylate monomers such as acrylic acid, hydroxyethyl acrylate, glycidyl acrylate, methacrylic acid, hydroxybutyl methacrylate or glycidyl methacrylate and non-functional unsaturated (meth)acrylate monomers such as ethyl acrylate, butyl acrylate, ethylhexyl acrylate, methyl methacrylate, ethyl acrylate and/or butyl methacrylate and/or C8-C20 vinylaromatics. Preference is given to copolymers based on methacrylic acid, hydroxyethyl acrylate, methyl methacrylate and styrene.
Examples of reactive polymers of the polyamide type which may be present in the compositions for producing amino resin products at up to 30% by mass, based on the melamine resin precondensates, are polyamide 6, polyamine 6,6, polyamide 11, polyamide 12, polyaminoamides formed from polycarboxylic acids and polyalkyleneamines, and the corresponding methoxylated polyamides.
Examples of reactive polymers of the polyester type which may be present in the compositions for producing amino resin products at up to 30% by mass, based on the melamine resin precondensates, are polyesters having molar masses of 2 000 to 15 000, formed from saturated dicarboxylic acids such as phthalic acid, isophthalic acid, adipic acid and/or succinic acid, unsaturated dicarboxylic acids such as maleic acid, fumaric acid and/or itaconic acid and diols such as ethylene glycol, butanediol, neopentylglycol and/or hexanediol. Preference is given to branched polyesters based on neopentylglycol, trimethylolpropane, isophthalic acid and azelaic acid.
Examples of reactive polymers of the polyurethane type that may be present in the compositions for producing amino resin products at up to 30% by mass, based on the melamine resin precondensates, are uncrosslinked polyurethanes based on tolylene diisocyanate, diphenylmethyl diisocyanate, butane diisocyanate and/or hexane diisocyanate as diisocyanate components and butanediol, hexanediol and/or polyalkylene glycols as diol components with molar masses of 2 000 to 30 000.
Examples of suitable stabilizers and UV absorbers which may be present in the compositions for producing amino resin products at up to 2% by mass, based on the melamine resin precondensates, are piperidine derivatives, benzophenone derivatives, benzotriazole derivatives, triazine derivatives and/or benzofuranone derivatives.
Examples of suitable auxiliaries which may be present in the compositions for producing amino resin products at up to 4% by mass, based on the melamine resin precondensates, are processing auxiliaries such as calcium stearate, magnesium stearate and/or waxes.
Also in accordance with the invention is a process for producing products from the above-described compositions for producing amino resin products, produced by melt processing, wherein the compositions are melted in continuous compounders at melt temperatures of 105 to 220° C. and residence times of 2 to 12 min and, with curing of the meltable melamine resin polycondensates, by customary processing methods for thermoplastic polymers,
For the production of products from the compositions of the invention comprising fillers, reinforcing fibres, other reactive polymers, stabilizers, UV absorbers and/or auxiliaries it is possible to use compositions in which these components are already present, or the components are added during the processing of the compositions.
Suitable continuous compounders for the melting of the compositions of the invention are extruders having short-compression screws or three-section screws with L/D=20-40. Preference is given to 5-section screws with an intake zone, compression zone, shearing zone, decompression zone and homogenizing zone. Screws with depths of cut of 1:2.5 to 1:3.5 are suitable with preference. The interposition of static mixers or melt pumps between barrel and die is particularly favourable.
Favourable melt temperatures for the melted compositions in the case of processing by the smoothing unit technology to form sheets or coatings or in the production of sheets, profiles or pipes by extrusion from a profile die are in the range from 110 to 150° C.
In the case of the production of foamed sheet material by discharge through a slot die it is possible to use compositions which comprise gas-evolving blowing agents such as sodium hydrogencarbonate, azodicarboxamide, citric acid/bicarbonate blowing systems and/or cyanuric trihydrazide, or volatile hydrocarbons such as pentane, isopentane, propane and/or isobutane, or gases such as nitrogen, argon and/or carbon dioxide, are introduced into the melt prior to discharge. Suitable die temperatures for the discharge of the melt containing blowing agents are 110 to 175° C. Preferred foam densities of the foams formed from the compositions of the invention are in the range from 10 to 500 kg/m2.
For the extrusion coating of metal pipes it is necessary for the temperatures of the melts of the compositions to be 135° C. to 220° C. and for the pipe material to be preheated at 100 to 160° C.
In the production of injection-moulded products from the compositions of the invention it is preferred to use injection moulding machines having injection units which possess three-section screws with a screw length of 18 to 24 D. The injection rate when producing the mouldings produced by injection moulding should be set as high as possible in order to eliminate sink marks and poor seams.
In the production of fibre products from the compositions of the invention it is preferred, for the uniform metering of the melt of the compositions melted in the plastifying extruder via the melt distributor to the capillary die, to use biphenyl-heated melt pumps for the melts heated at 120-240° C.
The production of filament yarns from the compositions of the invention can take place in short-spinning units by means of filament take-off with the aid of high-speed godets and further processing in downstream installations comprising aftercure chamber, drawing equipment and winders.
Fibres or non-wovens as products formed from the compositions of the invention can likewise be produced by the melt-blown process, by applying a stream of air heated to high temperatures around the apertures in the capillary die during the extrusion of the filaments from the capillary die into the blowing shaft. The stream of air stretches the melted filament and at the same time divides it into a large number of small individual fibres with diameters of 0.5 to 12 μm. Further processing of the fibres deposited on the screen conveyor belt, to form non-wovens, can be accomplished by applying thermobonding or needling operations in order to achieve the required strength and dimensional stability.
Fibre-reinforced plastics by the resin infusion process can be produced by impregnating the semi-finished fibre products by means of the melt of the composition of the invention that is under ambient pressure, which is pressed into the evacuated vacuum bag, with the use of an open mould.
Sheetlike components or components of complex shape by the resin injection process are produced by inserting preforms made of non-impregnated textiles into a lockable mould, injecting the melt of the composition of the invention, and carrying out curing.
Rotationally symmetric components by the filament winding process, complex components by the circular braiding technique or profiles by the pultrusion technique can be produced by impregnating the fibre blanks in the form of pipes, fittings, containers or profiles with the melt of the composition of the invention.
The invention is illustrated by the following examples:
The meltable melamine resin polycondensate used in the composition is a polytriazine ether formed from melamine and formaldehyde with a melamine/formaldehyde ratio of 1:3. The methylol groups have been predominantly etherified by methanol, so that the methoxy group content of the resin is 20% by mass. The molar mass of the polytriazine ether is around 2 000 g/mol.
1% by mass of maleic acid, based on the melamine resin polycondensate, is added as thermoinducible curing agent to the meltable melamine resin polycondensate, and the progress of curing of the composition is characterized by means of dynamic mechanical analysis. Analyses were carried out on an RDS instrument from the company Rheometric Scientific. The compositions were heated from 60° C. to 300° C. at a rate of 10 K/min and the progress of the viscosity was determined. As the onset, the temperature was determined at which a sharp increase in viscosity is observed (FIG. 1).
The onset temperature of the composition is 135° C. In the comparative experiment without thermoinducible curing agent the onset temperature is 200° C.
Experiment procedure analogous to Example 1; instead of maleic anhydride as thermoinducible curing agent, the curing agents indicated in Table 1 were used:
In comparative experiment 8 p-toluenesulphonic acid, as a strong acid, was used as thermoinducible curing agent. The composition with the strong acid gives an onset temperature which is higher by 45 to 90° C. in relation to the compositions of the invention, or the same onset temperature as in compositions without thermoinducible curing agents (comparative experiment 9).
The melamine resin used is a melamine-formaldehyde precondensate based on 2,4,6-trismethoxymethylamino-1,3,5-triazine which has been transetherified with an ethylene glycol diether of bisphenol A (Simulsol BPLE, Seppic S.A., France). The molar mass determined by GPC is 1 800, the amount of unreacted Simulsol BPLE by HPLC analysis (solution in THF, UV detection with external standard) is 14% by mass. The fraction of —OCH3 groups in the transetherified melamine resin (determination by GC analysis following cleavage of the polytriazine ether with mineral acid) is 14.5% by mass. The viscosity at 140° C. is 800 Pas.
The transetherification of the melamine-formaldehyde precondensate based on 2,4,6-trismethoxymethylamino-1,3,5-triazine and further condensation takes place at 220° C. in a GL 27 D44 laboratory extruder with vacuum devolatilization (Leistritz) with a temperature profile of 100° C./130° C./130° C./200° C./200° C./200° C./200° C./200° C./200° C./100° C./100° C. and an average residence time of 2.5 min. The extruder speed is 150 min−1. Metered gravimetrically into the intake zone of the extruder by means of side-stream metering are 2,4,6-trismethoxymethylamino-1,3,5-triazine at 1.38 kg/h and the ethylene glycol diether of bisphenol A at 1.13 kg/h. The strand of the polytriazine ether that emerges from the extruder is chopped in a pelletizer.
The transetherified resin is compounded with 1% by mass of maleic acid and the progress of curing this compound is determined in analogy to Example 1 by means of Dynamic Mechanical Analysis. The onset temperature in this example is 125° C.
Experimental procedure analogous to Example 10, using the curing agents indicated in Table 2:
FIG. 1
Progress of curing in the compositions according to Example 1 without thermoinducible curing agent and with 1% by mass of maleic acid, based on the melamine resin polycondensate, as thermoinducible curing agent
Number | Date | Country | Kind |
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A 904/2002 | Jun 2002 | AT | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP03/06175 | 6/12/2003 | WO | 6/30/2005 |