Patent Application
20230068858
The invention relates to amine-functional adducts of diamines with diepoxides and to the use thereof as curing agents for epoxy resin compositions that are particularly suitable as floor coatings.
Coatings based on epoxy resins are widely used in the building trade. They consist of liquid resin and curing agent components, which are mixed before application and then cure at ambient temperatures within a range from about 5 to 35° C. When applied, the viscosity of the coatings should be as low as possible so that they flow well at ambient temperature. After application, they should also cure as quickly as possible and without defects, even under damp and cold conditions, and form a defect-free surface without haze, spots, tack or craters. Once cured, they should have high hardness coupled with low brittleness and a high glass transition temperature in order to withstand mechanical stress as well as possible. For visually demanding applications, for example top coverings of floors, they should additionally have a high level of gloss and a minimal tendency to yellowing under the influence of light.
However, such epoxy resin coatings often have a tendency to surface defects such as haze, spots, roughness or tack, which is also referred to as “blushing”. Blushing is caused by the amines present in the curing agent component forming a salt with carbon dioxide from the air and occurs particularly at high humidity and low temperatures. Many curing agents for epoxy resin coatings comprise adducts of diamines with epoxy resin. This reduces blushing effects and also permits more rapid curing. However, diamine-epoxy resin adducts are significantly more viscous than the free diamines. In order to limit the viscosity, the diamine is used in a large stoichiometric excess relative to the epoxy resin. The content of unreacted diamine and the distribution of the various adduct molecules varies according to the stoichiometry and the level of the diamine excess used in the production of the adducts. Adducts produced using a low excess of diamine contain less unreacted diamine and more higher-molecular-weight adduct molecules having two, three or more diepoxide units. Such adducts would themselves be advantageous. They have low odor, a particularly low tendency to blushing, and make it possible for the adduct to be used in large amounts and/or to be combined with further amines. Adducts produced with a low excess of diamine are however very highly viscous or even solid, consequently it is possible to handle them at room temperature only with considerable amounts of thinners such as benzyl alcohol. Thinners are not incorporated into the resin matrix during curing and may be released into the environment through evaporation or diffusion processes. Nowadays, there is however an increasing desire for low-emission products that after curing have a low content of releasable substances. For low-emission or emission-free epoxy resin compositions, thinners of this kind can therefore be used only in small amounts or not at all.
WO 2017/046293 discloses adducts of N-benzylpropane-1,2-diamine or N-benzylethane-1,2-diamine and bisphenol A diglycidyl ether that are purified by distillation and permit coatings having nice surfaces. These adducts are produced using a large excess of diamine, which severely limits the freedom to combine them with further amines.
Also known are adducts of alkylated diamines with epoxides as a constituent of curing agents for aqueous epoxy resin products, for example from EP 1 956 034. The adducts contain polyether chains and, after the reaction, are thinned with unadducted diamines and large amounts of water.
It is therefore an object of the present invention to provide a diamine-epoxy resin adduct that, even with a low excess of diamine during production without addition of thinners, is liquid at room temperature and has the lowest possible viscosity and that, when used as a curing agent for epoxy resin coatings, allows good processability, rapid curing, and defect-free, glossy surfaces, even in damp and cold conditions.
This object is achieved with the adduct as described in claim 1. This is obtained by reacting an amine mixture comprising a monoalkylated diamine and a dialkylated diamine with a diepoxide in a stoichiometric ratio of at least 1.2 moles of monoalkylated diamine to 1 mole equivalent of epoxy groups.
Despite the low excess of diamine, the adduct of the invention is liquid at room temperature and has surprisingly low viscosity. Even with a low content of dialkylated diamine, the adduct is much less viscous than a corresponding adduct produced in the absence of the dialkylated diamine. Surprisingly, when the adduct is used as a curing agent for epoxy resins, neither the rate of curing nor the final hardness are adversely affected to any significant extent by the dialkylated diamine. The much lower viscosity of the adduct is very advantageous and could not have been expected on the basis of the prior art.
The adduct of the invention is particularly inexpensive, since it can be obtained from an amine mixture that is technically simple to produce.
The adduct of the invention permits low-emission or emission-free epoxy resin coatings having surprisingly good processability and surprisingly rapid curing, that have high hardness and low tendency to yellowing, and that have little tendency to blushing-related defects even under damp and cold conditions.
Further aspects of the invention are the subject of further independent claims.
Particularly preferred embodiments of the invention are the subject of the dependent claims.
The invention provides an amine-functional adduct from the reaction of
where
A “primary amino group” refers to an amino group that is attached to a single organic radical and bears two hydrogen atoms; a “secondary amino group” refers to an amino group that is attached to two organic radicals, which may also together be part of a ring, and bears one hydrogen atom; and a “tertiary amino group” refers to an amino group that is attached to three organic radicals, two or three of which may also be part of one or more rings, and does not bear any hydrogen atoms.
“Amine hydrogen” refers to the hydrogen atoms of primary and secondary amino groups.
“Amine hydrogen equivalent weight” refers to the mass of an amine or an amine-containing composition that contains one molar equivalent of amine hydrogen. It is expressed in units of “g/equiv.”.
The “epoxide equivalent weight” refers to the mass of an epoxy group-containing compound or composition that contains one molar equivalent of epoxy groups. It is expressed in units of “g/equiv.”.
Substance names beginning with “poly”, such as polyamine or polyepoxide, refer to substances that formally contain two or more of the functional groups that occur in their name per molecule.
A “thinner” refers to a substance that is soluble in an epoxy resin and lowers its viscosity, and that is not chemically incorporated into the epoxy resin polymer during the curing process.
“Molecular weight” refers to the molar mass (in grams per mole) of a molecule. “Average molecular weight” refers to the number-average Mn of a polydisperse mixture of oligomeric or polymeric molecules, which is normally determined by gel-permeation chromatography (GPC) against polystyrene as standard.
The “gel time” is the time interval from mixing the components of an epoxy resin composition until the gelation thereof.
“Room temperature” refers to a temperature of 23° C.
The amine mixture used for the adduct of the invention preferably contains only low amounts of other amines not corresponding to formulas (I) and (II) or none at all. The amine mixture preferably has a purity based on the sum of diamine of formula (I) and diamine of formula (II) of at least 95% by weight, in particular at least 97% by weight.
The amine mixture used for production of the adduct preferably has a content of diamine of formula H2N-A-NH2, where A is as defined above, of not more than 5% by weight, preferably not more than 3% by weight, more preferably not more than 2% by weight, in particular not more than 1% by weight. Such an amine mixture has a particularly low odor and permits low-viscosity adducts that cause virtually no blushing when used as curing agents for epoxy resins.
A is preferably selected from the group consisting of 1,2-ethylene, 1,2-propylene, 1,3-propylene, 1,4-butylene, 1,3-butylene, 2-methyl-1,2-propylene, 1,3-pentylene, 1,5-pentylene, 2,2-dimethyl-1,3-propylene, 1,6-hexylene, 2-methyl-1,5-pentylene, 1,7-heptylene, 1,8-octylene, 2,5-dimethyl-1,6-hexylene, 1,9-nonylene, 2,2(4),4-trimethyl-1,6-hexylene, 1,10-decylene, 1,11-undecylene, 2-butyl-2-ethyl-1,5-pentylene, 1,12-dodecylene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, (1,5,5-trimethylcyclohexan-1-yl)methane-1,3, 4(2)-methyl-1,3-cyclohexylene, 1,3-cyclohexylenebis(methylene), 1,4-cyclohexylenebis(methylene), 1,3-phenylenebis(methylene), and 1,4-phenylenebis(methylene). These diamines of formula (I) and (II) are derived from commercially readily available primary diamines.
A is especially selected from the group consisting of 1,2-ethylene, 1,2-propylene, 2-methyl-1,2-propylene, 1,3-pentylene, 1,2-cyclohexylene, 1,4-cyclohexylene, 4(2)-methyl-1,3-cyclohexylene, 1,3-cyclohexylenebis(methylene), 1,4-cyclohexylenebis(methylene), 1,3-phenylenebis(methylene), and 1,4-phenylenebis(methylene).
A is most preferably 1,2-ethylene. These diamines of formula (I) and (II) permit adducts having particularly low viscosity and particularly high reactivity and permit a particularly low tendency to yellowing.
R is preferably selected from the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, 3-methylbut-2-yl, hexyl, 4-methylpent-2-yl, 2-ethylhexyl, octyl, nonyl, decyl, undecyl, dodecyl, and an optionally substituted 1-phenylethyl, 2-phenylethyl, benzyl, naphthylmethyl, cyclohexylmethyl, and 2-cyclohexylethyl radical.
Preference is given to radicals R having 6 to 12 carbon atoms, especially 6 to 8 carbon atoms.
R is particularly preferably selected from the group consisting of 2-ethylhexyl, 2-phenylethyl, benzyl, 1-naphthylmethyl, and cyclohexylmethyl.
Most preferably, R is benzyl. These diamines of formulas (I) and (II) permit adducts having particularly low viscosity and high reactivity as well as particularly little tendency to blushing effects and yellowing, especially when combined with radicals A that are free from aromatic groups.
The diamine of formula (I) is particularly preferably selected from the group consisting of N-benzylethane-1,2-diamine, N-(1-naphthylmethyl)ethane-1,2-diamine, N-cyclohexylmethylethane-1,2-diamine, N-benzylpropane-1,2-diamine, and N-(2-ethylhexyl)-1,3-bis(aminomethyl)benzene.
The most preferred diamine of formula (I) is N-benzylethane-1,2-diamine. This diamine permits particularly low-viscosity and reactive adducts.
The radicals A and R in the diamines of formulas (I) and (II) are preferably identical radicals. Such an amine mixture is particularly readily available as a reaction product of an alkylation.
Particularly preferably, the diamine of formula (I) is N-benzylethane-1,2-diamine and the diamine of formula (II) is N,N′-dibenzylethane-1,2-diamine.
The weight ratio between the diamine of formula (I) and the diamine of formula (II) is preferably within a range from 70/30 to 95/5, more preferably 80/20 to 90/10.
Such an adduct is particularly reactive and permits high hardnesses.
The diamine of formula (I) and the diamine of formula (II) are preferably produced by partial alkylation of at least one amine of formula H2N-A-NH2 with at least one alkylating agent.
The alkylation is preferably a reductive alkylation using an aldehyde or ketone as the alkylating agent and hydrogen.
Preference is given to carrying out the reductive alkylation in the presence of a suitable catalyst. Preferred catalysts are palladium on charcoal (Pd/C), platinum on charcoal (Pt/C), Adams' catalyst or Raney nickel, especially palladium on charcoal or Raney nickel.
When molecular hydrogen is used, the reductive alkylation is preferably operated in a pressure apparatus at a hydrogen pressure of 5 to 150 bar, especially 10 to 100 bar. This can take place in a batchwise process or preferably in a continuous process.
The reductive alkylation is preferably carried out at a temperature within a range from 40 to 120° C., in particular 60 to 100° C.
In the case of small volatile amines such as ethane-1,2-diamine or propane-1,2-diamine in particular, this is preferably used in a stoichiometric excess relative to the aldehyde or ketone and, after the alkylation, some or all of the unreacted amine is removed from the reaction mixture, especially by distillation or stripping.
Where A and R in the diamines of formula (I) and (II) are identical radicals, the reaction product obtained may be used as an amine mixture without further purification.
It is however also possible for the diamine of formula (I) and the diamine of formula (II) to each be produced separately and mixed to form the amine mixture.
For this, the reaction mixture from the reductive alkylation is preferably purified further, especially by distillation.
The reaction mixture is preferably not purified further, but instead contains the diamine of formula (I) and the diamine of formula (II) in the ratio according to the invention. Such a reaction mixture is particularly inexpensive.
The amine mixture comprising at least one diamine of formula (I) and at least one diamine of formula (II) is preferably a reaction product from the reductive alkylation of at least one amine of formula H2N-A-NH2 with at least one aldehyde or ketone and hydrogen.
Preference as the aldehyde or ketone is given to formaldehyde, acetaldehyde, 1-propanal, acetone, 1-butanal, isobutyraldehyde, methyl ethyl ketone, 1-pentanal, methyl isopropyl ketone, 1-hexanal, methyl isobutyl ketone, 2-ethylhexanal, 1-octanal, 1-nonanal, 1-decanal, 1-undecanal, 1-dodecanal, methyl phenyl ketone, benzaldehyde, 1-naphthaldehyde or cyclohexanecarbaldehyde.
Particular preference is given to 2-ethylhexanal, benzaldehyde, 1-naphthaldehyde or cyclohexanecarbaldehyde, especially benzaldehyde.
The amine of formula H2N-A-NH2 is particularly preferably ethane-1,2-diamine.
The diepoxide is preferably an aromatic diepoxide. A diepoxide is referred to as “aromatic” if it contains at least one aromatic ring.
The aromatic diepoxide is preferably free of polyether chains. Such an aromatic diepoxide is particularly suitable as a curing agent for nonaqueous epoxy resin products, which are particularly stable to weathering influences.
The diepoxide is preferably selected from the group consisting of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, mixtures of bisphenol A diglycidyl ether and bisphenol F diglycidyl ether, catechol diglycidyl ether, resorcinol diglycidyl ether, hydroquinone diglycidyl ether, bis(4-hydroxy-3-methylphenyl)methane diglycidyl ether, 2,2-bis(4-hydroxy-3-methylphenyl)propane diglycidyl ether, bis(3,5-dimethyl-4-hydroxyphenyl)methane diglycidyl ether, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane diglycidyl ether, 2,2-bis(4-hydroxy-3-tert-butylphenyl)propane diglycidyl ether, 2,2-bis(4-hydroxyphenyl)butane diglycidyl ether, 3,3-bis(4-hydroxyphenyl)pentane diglycidyl ether, 3,4-bis(4-hydroxyphenyl)hexane diglycidyl ether, 4,4-bis(4-hydroxyphenyl)heptane diglycidyl ether, 2,4-bis(4-hydroxyphenyl)-2-methylbutane diglycidyl ether, and 4,4′-dihydroxybiphenyl diglycidyl ether.
The diepoxide is particularly preferably a bisphenol A diglycidyl ether, bisphenol F diglycidyl ether or bisphenol NF diglycidyl ether, especially a bisphenol A diglycidyl ether.
The diglycidyl ethers are preferably used in a technical grade quality.
Particular preference is given to commercially available liquid resins, such as in particular Araldite® GY 240, Araldite® GY 250, Araldite® GY 281, Araldite® GY 282, Araldite® GY 285, Araldite® PY 304 or Araldite® PY 720 (all from Huntsman), or D.E.R.®330, D.E.R.®331, D.E.R.®332, D.E.R.®336, D.E.R.®351, D.E.R.®352, D.E.R.®354 or D.E.R.®356 (all from Dow).
The diepoxide preferably has an epoxide equivalent weight within a range from 110 to 260 g/equiv., preferably 156 to 200 g/equiv.
The amine mixture is preferably used in the reaction to the adduct of the invention in an amount such that the stoichiometric ratio is within a range from 1.3 to 2, in particular 1.4 to 1.7, moles of diamine of formula (I) to 1 molar equivalent of epoxy groups of the diepoxide.
Such an adduct contains particularly little unreacted diamine and a high content of adduct molecules. It has a particularly low odor and surprisingly low viscosity. It permits particularly rapid curing and high flexibility for combining with further amines.
Preferably, the temperature during the reaction is within a range from 40 to 120° C., especially 60 to 100° C.
After the reaction, unreacted diamine of formula (I) and diamine of formula (II) is preferably not removed from the adduct but remains therein and is a constituent of the adduct.
The adduct contains so-called 2:1 adducts from the addition of 2 moles of diamine of formula (I) or (II) and 1 mole of diepoxide. In the case of N-benzylethane-1,2-diamine as the diamine of formula (I), N,N′-dibenzylethane-1,2-diamine as the diamine of formula (II), and bisphenol A diglycidyl ether, the adduct mainly contains the following 2:1 adduct,
wherein further 2:1 adducts formed through addition of secondary amino groups to epoxy groups are also present, for example those shown below
The adduct also contains higher adducts, in particular so-called 3:2 adducts from the addition of 3 moles of diamine of formula (I) or (II) and 2 moles of diepoxide. In the case of N-benzylethane-1,2-diamine as the diamine of formula (I) and bisphenol A diglycidyl ether, it is mainly the following 3:2 adduct
that is present, alongside 3:2 adducts from reaction with secondary amino groups.
The adduct also contains further higher adducts, so-called >3:2 adducts, in particular those from the addition of 4 moles of diamine of formula (I) or (II) and 3 moles of diepoxide or 5 moles of diamine of formula (I) or (II) and 4 moles of diepoxide.
The adduct of the invention preferably contains 2:1 adducts and higher adducts in a weight ratio within a range from 30/70 to 80/20, preferably 35/65 to 70/30. Such an adduct permits a particularly advantageous combination of low viscosity and rapid curing.
The adduct of the invention particularly preferably contains 2:1 adducts and higher adducts in a weight ratio within a range from 30/70 to 49.9/50.1, in particular 35/65 to 49/51. Such an adduct is especially produced in a stoichiometric ratio within a range from 1.4 to 1.7 moles of diamine of formula (I) to 1 molar equivalent of epoxy groups of the diepoxide. It permits particularly rapid curing.
The adduct preferably contains less than 1% by weight of thinner or water.
The adduct preferably has a viscosity at 20° C. within a range from 5 to 500 Pa.s, preferably 10 to 250 Pa.s, especially 20 to 150 Pa.s, measured using a cone-plate viscometer at a shear rate of 10 s−1.
The adduct of the invention is particularly suitable for curing an epoxy resin.
The invention further provides a curing agent for epoxy resins, comprising the adduct of the invention and at least one further constituent selected from the group consisting of further amines, accelerators, and thinners.
The curing agent preferably contains 1% to 80% by weight, preferably 2% to 60% by weight, especially 5% to 50% by weight, of the adduct of the invention.
The curing agent for epoxy resins is preferably not water-based. It especially contains less than 15% by weight, preferably less than 10% by weight, of water. Such a curing agent is suitable for nonaqueous epoxy resin products, especially floor coatings.
The curing agent preferably comprises at least one further amine having aliphatic amino groups and at least three amine hydrogens. This further amine is preferably mixed into the adduct only after the reaction of the amine mixture with the diepoxide has taken place. This further amine may be the same amine as the one used in the reaction to form the adduct as the diamine of formula (I), or it may be a different amine.
Suitable further amines are especially N-benzylethane-1,2-diamine, N-benzylpropane-1,2-diamine, N-benzyl-1,3-bis(aminomethyl)benzene, N-(2-ethylhexyl)-1,3-bis(aminomethyl)benzene or N-(2-phenylethyl)-1,3-bis(aminomethyl)benzene, and also 2,2-dimethylpropane-1,3-diamine, pentane-1,3-diamine (DAMP), pentane-1,5-diamine, 1,5-diamino-2-methylpentane (MPMD), 2-butyl-2-ethylpentane-1,5-diamine (C11-neodiamine), hexane-1,6-diamine, 2,5-dimethylhexane-1,6-diamine, 2,2(4),4-trimethylhexane-1,6-diamine (TMD), heptane-1,7-diamine, octane-1,8-diamine, nonane-1,9-diamine, decane-1,10-diamine, undecane-1,11-diamine, dodecane-1,12-diamine, 1,2-, 1,3- or 1,4-diaminocyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane, bis(4-amino-3-methylcyclohexyl)methane, bis(4-amino-3-ethylcyclohexyl)methane, bis(4-amino-3,5-dimethylcyclohexyl)methane, bis(4-amino-3-ethyl-5-methylcyclohexyl)methane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (IPDA), 2(4)-methyl-1,3-diaminocyclohexane, 2,5(2,6)-bis(aminomethyl)bicyclo[2.2.1]heptane (NBDA), 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.02.6]decane, 1,4-diamino-2,2,6-trimethylcyclohexane (TMCDA), menthane-1,8-diamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3-bis(aminomethyl)benzene (MXDA), 1,4-bis(aminomethyl)benzene, bis(2-aminoethyl) ether, 3,6-dioxaoctane-1,8-diamine, 4,7-dioxadecane-1,10-diamine, 4,7-dioxadecane-2,9-diamine, 4,9-dioxadodecane-1,12-diamine, 5,8-dioxadodecane-3,10-diamine, 4,7,10-trioxatridecane-1,13-diamine or higher oligomers of these diamines, bis(3-aminopropyl)polytetrahydrofurans or other polytetrahydrofurandiamines, polyoxyalkylenediamines or -triamines, especially polyoxypropylenediamines or polyoxypropylenetriamines such as Jeffamine® D-230, Jeffamine® D-400 or Jeffamine® T-403 (all from Huntsman), diethylene triamine (DETA), triethylene tetramine (TETA), tetraethylene pentamine (TEPA), pentaethylene hexamine (PEHA), dipropylene triamine (DPTA), N-(2-aminoethyl)propane-1,3-diamine (N3-amine), N,N′-bis(3-aminopropyl)ethylenediamine (N4-amine), N,N′-bis(3-aminopropyl)-1,4-diaminobutane, N5-(3-aminopropyl)-2-methylpentane-1,5-diamine, N3-(3-aminopentyl)pentane-1,3-diamine, N5-(3-amino-1-ethylpropyl)-2-methylpentane-1,5-diamine, N,N′-bis(3-amino-1-ethylpropyl)-2-methylpentane-1,5-diamine, 3-(2-aminoethyl)aminopropylamine, bis(hexamethylene)triamine (BHMT), N-aminoethylpiperazine, 3-dimethylaminopropylamine (DMAPA) or 3-(3-(dimethylamino)propylamino)propylamine (DMAPAPA).
It may be advantageous when the curing agent of the invention comprises a combination of two or more further amines.
Preference is given to further amines selected from the group consisting of N-benzylethane-1,2-diamine, N-benzylpropane-1,2-diamine, N-benzyl-1,3-bis(aminomethyl)benzene, N-(2-ethylhexyl)-1,3-bis(aminomethyl)benzene, N-(2-phenylethyl)-1,3-bis(aminomethyl)benzene, TMD, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane, IPDA, 2(4)-methyl-1,3-diaminocyclohexane, MXDA, polyoxypropylenediamines having an average molecular weight Mn within a range from 200 to 500 g/mol, polyoxypropylene triamines having an average molecular weight Mn within a range from 300 to 500 g/mol, DMAPAPA, BHMT, DETA, TETA, TEPA, PEHA, DPTA, N3-amine and N4-amine.
The curing agent particularly preferably comprises at least one further amine selected from the group consisting of N-benzylethane-1,2-diamine, TMD, 1,2-diaminocyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, IPDA, 2(4)-methyl-1,3-diaminocyclohexane, MXDA, polyoxypropylene diamines having an average molecular weight Mn within a range from 200 to 500 g/mol, and polyoxypropylene triamines having an average molecular weight Mn within a range from 300 to 500 g/mol.
A particularly preferred further amine is N-benzylethane-1,2-diamine. This amine permits curing agents having particularly good processability, rapid curing and little tendency to blushing effects.
Another particularly preferred further amine is MXDA, optionally in the form of an amine-functional adduct with an epoxy resin. This amine permits particularly rapid curing.
Another particularly preferred further amine is IPDA, optionally in the form of an amine-functional adduct with an epoxy resin. This amine permits a particularly high glass transition temperature and final hardness.
Suitable accelerators are especially acids or compounds hydrolyzable to acids, especially organic carboxylic acids such as acetic acid, benzoic acid, salicylic acid, 2-nitrobenzoic acid, lactic acid, organic sulfonic acids such as methanesulfonic acid, p-toluenesulfonic acid or 4-dodecylbenzenesulfonic acid, sulfonic esters, other organic or inorganic acids, such as phosphoric acid in particular, or mixtures of the abovementioned acids and acid esters; nitrates such as calcium nitrate in particular; tertiary amines such as in particular 1,4-diazabicyclo[2.2.2]octane, benzyldimethylamine, α-methylbenzyldimethylamine, triethanolamine, dimethylaminopropylamine, imidazoles such as in particular N-methylimidazole, N-vinylimidazole or 1,2-dimethylimidazole, salts of such tertiary amines, quaternary ammonium salts, such as benzyltrimethylammonium chloride in particular, amidines, such as 1,8-diazabicyclo[5.4.0]undec-7-ene in particular, guanidines, such as 1,1,3,3-tetramethylguanidine in particular, phenols, especially bisphenols, phenolic resins or Mannich bases such as in particular 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol or polymers produced from phenol, formaldehyde and N,N-dimethylpropane-1,3-diamine, phosphites such as in particular di- or triphenyl phosphites, or compounds having mercapto groups.
Preference is given to acids, nitrates, tertiary amines or Mannich bases, especially salicylic acid, calcium nitrate or 2,4,6-tris(dimethylaminomethyl)phenol, or a combination of these accelerators.
Suitable thinners are especially xylene, 2-methoxyethanol, dimethoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, 2-phenoxyethanol, 2-benzyloxyethanol, benzyl alcohol, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, ethylene glycol diphenyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-butyl ether, propylene glycol butyl ether, propylene glycol phenyl ether, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol di-n-butyl ether, diphenylmethane, diisopropylnaphthalene, mineral oil fractions, for example Solvesso® grades (from Exxon), alkylphenols such as tert-butylphenol, nonylphenol, dodecylphenol, cardanol (from cashew nut shell oil, containing 3-(8,11-pentadecadienyl)phenol as its principal constituent), styrenized phenol, bisphenols, aromatic hydrocarbon resins, especially types containing phenol groups, alkoxylated phenol, especially ethoxylated or propoxylated phenol, especially 2-phenoxyethanol, adipates, sebacates, phthalates, benzoates, organic phosphoric or sulfonic esters or sulfonamides.
Preferred thinners have a boiling point of more than 200° C.
The thinner is preferably selected from the group consisting of benzyl alcohol, styrenized phenol, ethoxylated phenol, aromatic hydrocarbon resins containing phenol groups, especially the Novares® LS 500, LX 200, LA 300 or LA 700 products (from Rutgers), diisopropylnaphthalene and cardanol.
Particular preference is given to benzyl alcohol.
Thinners containing phenol groups are also effective as accelerator.
The curing agent may comprise further constituents, especially the following:
The present invention further provides an epoxy resin composition comprising
The curing agent component preferably comprises the curing agent described above.
A suitable epoxy resin is obtained in a known manner especially from the reaction of epichlorohydrin with polyols, polyphenols or amines.
Suitable epoxy resins are especially aromatic epoxy resins, especially the glycidyl ethers of:
Further suitable epoxy resins are aliphatic or cycloaliphatic polyepoxides, especially
The epoxy resin is preferably a liquid resin or a mixture comprising two or more liquid epoxy resins.
“Liquid epoxy resin” refers to an industrial polyepoxide having a glass transition temperature below 25° C.
The resin component optionally additionally contains proportions of solid epoxy resin.
The epoxy resin is especially a liquid resin based on a bisphenol, especially a bisphenol A diglycidyl ether and/or bisphenol F diglycidyl ether, as are commercially available for example from Olin, Huntsman or Momentive. These liquid resins have a low viscosity for epoxy resins and permit rapid curing and high hardnesses. They may comprise proportions of solid bisphenol A resin or novolak glycidyl ethers.
The resin component may comprise a reactive diluent.
Preferred reactive diluents are reactive diluents containing epoxy groups, especially butanediol diglycidyl ether, hexanediol diglycidyl ether, trimethylolpropane di- or triglycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, guaiacol glycidyl ether, 4-methoxyphenyl glycidyl ether, p-n-butylphenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, 4-nonylphenyl glycidyl ether, 4-dodecylphenyl glycidyl ether, cardanol glycidyl ether, benzyl glycidyl ether, allyl glycidyl ether, butyl glycidyl ether, hexyl glycidyl ether, 2-ethylhexyl glycidyl ether, or glycidyl ethers of natural alcohols, such as in particular C8 to C10 or C12 to C14 or C13 to C15 alkyl glycidyl ethers.
The epoxy resin composition preferably comprises at least one further constituent selected from the group consisting of thinners, accelerators and fillers.
Suitable accelerators are those already mentioned, especially salicylic acid, calcium nitrate or 2,4,6-tris(dimethylaminomethyl)phenol or a combination thereof.
Suitable thinners are those already mentioned, especially those having a boiling point of more than 200° C.
The thinner is preferably selected from the group consisting of benzyl alcohol, styrenized phenol, ethoxylated phenol, aromatic hydrocarbon resins containing phenol groups, especially the Novares® LS 500, LX 200, LA 300 or LA 700 products (from Rutgers), diisopropylnaphthalene and cardanol.
Particular preference is given to benzyl alcohol.
Suitable fillers are, in particular, ground or precipitated calcium carbonate, which is optionally coated with fatty acid, especially stearates, baryte (heavy spar), talc, quartz powder, quartz sand, silicon carbide, iron mica, dolomite, wollastonite, kaolin, mica (potassium aluminum silicate), molecular sieve, aluminum oxide, aluminum hydroxide, magnesium hydroxide, silica, cement, gypsum, fly ash, carbon black, graphite, metal powders such as aluminum, copper, iron, zinc, silver or steel, PVC powder or hollow beads.
Preference is given to calcium carbonate, quartz flour, quartz sand or a combination thereof.
The epoxy resin composition may optionally comprise further auxiliaries and additives, especially the following:
The epoxy resin composition preferably comprises further auxiliaries and additives, especially pigments, wetting agents, leveling agents and/or defoamers.
The epoxy resin composition preferably has only a low content of thinners. It preferably contains less than 20% by weight, more preferably less than 15% by weight, especially less than 10% by weight, of thinners. This permits low-emission or emissions-free epoxy resin products.
The epoxy resin composition preferably has only a low content of water, preferably less than 5% by weight, in particular less than 1% by weight, of water.
In the epoxy resin composition, the ratio of the number of groups reactive toward epoxy groups relative to the number of epoxy groups is preferably within a range from 0.5 to 1.5, in particular 0.7 to 1.2.
The primary and secondary amino groups present in the epoxy resin composition, and any further groups present that are reactive toward epoxy groups, react with the epoxy groups, resulting in ring opening (addition reaction) thereof. As a result primarily of this reaction, the composition polymerizes and thereby cures.
The resin component and the curing agent component of the epoxy resin composition are stored in separate containers. Further constituents of the epoxy resin composition may be present as a constituent of the resin component or of the curing agent component; further constituents reactive toward epoxy groups are preferably a constituent of the curing agent component. It is likewise possible for further constituents to be present as a dedicated, further component.
A suitable container for storage of the resin component or the curing agent component is especially a vat, a hobbock, a bag, a bucket, a can, a cartridge or a tube. The components are storable, meaning that they can be stored prior to use for several months up to one year or longer without any change in their respective properties to a degree relevant to their use. For the use of the epoxy resin composition, the components are mixed with one another shortly before or during application. The mixing ratio between the resin component and the curing agent component is preferably chosen such that the groups of the curing agent component that are reactive toward epoxy groups are in a suitable ratio to the epoxy groups of the resin component, as described above. In parts by weight, the mixing ratio between the resin component and the curing agent component is normally within a range from 1:10 to 10:1.
The components are mixed by means of a suitable method; this mixing may be done continuously or batchwise. If the mixing does not immediately precede the application, it must be ensured that not too much time passes between mixing the components and the application thereof and that application takes place within the pot life. Mixing takes place in particular at ambient temperature, which is typically within a range from about 5 to 40° C., preferably about 10 to 35° C.
Curing by chemical reaction begins with the mixing of the two components, as described above. Curing typically takes place at a temperature within a range from 0 to 150° C. It preferably takes place at ambient temperature and typically extends over a period of a few days to weeks. The duration depends on factors including the temperature, the reactivity of the constituents, and the stoichiometry thereof, and on the presence of accelerators.
When freshly mixed, the epoxy resin composition has low viscosity. The viscosity at 20° C. 10 minutes after the resin component and curing agent component have been mixed is preferably within a range from 300 to 4000 mPas, preferably 300 to 3000 mPas, in particular 300 to 2000 mPa·s, measured using a cone-plate viscometer at a shear rate of 10 s−1.
The epoxy resin composition is applied to at least one substrate, the following substrates being particularly suitable:
If required, the substrates can be pretreated prior to application, especially by physical and/or chemical cleaning methods or the application of an activator or a primer.
The curing of the epoxy resin composition affords a cured composition.
The epoxy resin composition is preferably used as coating, primer, adhesive, sealant, potting compound, casting resin, impregnating resin or as matrix for fiber composites such as CFRP or GFRP in particular.
The epoxy resin composition is particularly preferably used as a coating. Coatings are understood here to mean coverings of all kinds that are applied over an area, especially floor coverings, paints, varnishes, sealants, basecoats, primers or protective coatings, especially also those for heavy-duty corrosion protection. The epoxy resin composition is particularly suitable as a floor covering or floor coating for interiors such as offices, industrial halls, sports halls or cold rooms, or outdoors for balconies, terraces, parking decks, bridges or roofs, as a protective coating for concrete, cement, metals, plastics or wood, for example for surface sealing of wood constructions, vehicles, loading areas, tanks, silos, shafts, pipelines, machines or steel constructions, for example of ships, piers, offshore platforms, lock gates, hydroelectric power plants, river constructions, swimming pools, wind turbines, bridges, chimneys, cranes or sheet-pile walls, or as an undercoat, tiecoat or anticorrosion primer or for hydrophobization of surfaces.
The epoxy resin composition is particularly advantageously used in low-emission coatings with environmental quality seals, for example in accordance with Emicode (EC1 Plus), AgBB, DIBt, Der Blaue Engel, AFSSET, RTS (M1) and US Green Building Council (LEED).
For use as a coating, the epoxy resin composition advantageously has a fluid consistency with low viscosity and good leveling properties. The mixed composition is typically applied, within its pot life, to the surface of a substrate as a thin film having a layer thickness of about 50 μm to about 5 mm, typically at ambient temperature. It is applied especially by pouring onto the substrate to be coated and then spreading it evenly using, for example, a doctor blade or a notched trowel. It may also be applied with a brush or roller or in the form of a spray application, for example as an anticorrosion coating on steel. Curing typically gives rise to substantially homogeneous, glossy and nontacky films of high hardness that have good adhesion to a wide variety of different substrates.
In this case, the epoxy resin composition is used in particular in a method for coating, comprising the steps of
It is possible to apply a further coating to the fully or partly cured composition, in which case said further layer may likewise be an epoxy resin composition, or else another material, especially a polyurethane or polyurea coating.
Particular preference is also given to using the epoxy resin composition as an adhesive. When used as adhesive, the epoxy resin composition typically has, after the components have been mixed, a pasty consistency with structurally viscous properties. On application, the mixed adhesive is applied within the pot life to at least one of the substrates to be bonded and the two substrates are joined to form an adhesive bond within the open time of the adhesive.
The mixed adhesive is applied especially by means of a brush, roll, spatula, doctor blade or trowel, or from a tube, cartridge or metering device.
The adhesive is particularly suitable for uses in the construction industry, especially for the reinforcement of built structures by means of steel lamellas or lamellas made of carbon fiber-reinforced composite plastics (CFRP), for constructions containing bonded precast concrete components, especially bridges or concrete towers, for example for wind turbines, shafts, pipelines or tunnels, or for constructions containing bonded natural rocks, ceramic elements or parts made of fiber cement, steel, cast iron, aluminum, wood or polyester, for the anchoring of dowels or steel bars in boreholes, for the fixing of, for example, handrails, balustrades or door frames, for repairs such as in particular the filling of edges, holes or joins in concrete maintenance, or for the bonding of films of polyvinyl chloride (PVC), flexibilized polyolefin (Combiflex®) or adhesion-modified chlorosulfonated polyethylene (Hypalon®) to concrete or steel.
Further fields of use relate to structural bonding in the construction or manufacturing industry, especially as adhesive mortar, assembly adhesive, reinforcement adhesive such as, in particular, for the bonding of lamellas made of CFRP or steel to concrete, brickwork or wood, as element adhesive, for example for bridge elements, sandwich element adhesive, facade element adhesive, reinforcing adhesive, bodywork adhesive or half-shell adhesive for rotor blades of wind turbines.
Such an epoxy resin adhesive is likewise suitable for filling cavities such as gaps, cracks or drill holes, wherein the adhesive is filled or injected into the cavity and fills it after curing, and bonds or sticks the flanks of the cavity to one another in a force-fitting manner.
In this case, the epoxy resin composition is used in particular in a method for bonding, comprising the steps of
An “anchor” refers here more particularly to a rebar, a threaded rod or a bolt. An anchor is in particular thus adhesive-bonded or anchored in a wall, ceiling or foundation in such a way that a portion thereof is bonded in a force-fitting manner and a portion thereof protrudes and can be subjected to a construction load.
Identical or different substrates may be bonded.
The application and curing of the epoxy resin composition afford an article. The invention thus further provides an article obtained from the use of the epoxy resin composition.
The article is preferably a built structure or part thereof, especially a built structure above or below ground, an office, an industrial hall, a sports hall, a cold room, a silo, a bridge, a roof, a staircase, a floor, a balcony, a terrace or a parking deck, or an industrial good or a consumer good, especially a pier, an offshore platform, a lock gate, a crane, a bulkhead, a pipeline or a rotor blade of a wind turbine, or a mode of transport such as in particular an automobile, a truck, a rail vehicle, a ship, an aircraft or helicopter, or an installable component thereof.
The epoxy resin composition is characterized by advantageous properties. It can also be formulated with little or no thinner, such formulations having surprisingly low viscosity and very good processability and curing reliably and surprisingly quickly, in particular even under damp and cold conditions. This results in coatings of high mechanical quality and having high surface quality. Such epoxy resin products are particularly suitable as coatings, especially for floors.
Working examples are adduced hereinafter, which are intended to further elucidate the invention described. The invention is of course not limited to these described working examples.
“ANEW” stands for amine hydrogen equivalent weight.
“EEW” stands for epoxy equivalent weight.
“Standard climatic conditions” (“SCC”) refer to a temperature of 23±1° C. and a relative air humidity of 50±5%.
The chemicals used were unless otherwise stated from Sigma-Aldrich Chemie GmbH.
The viscosity was measured on a thermostated Rheotec RC30 cone-plate viscometer (cone diameter 50 mm, cone angle 1°, cone tip-plate distance 0.05 mm, shear rate 10 s−1).
The amine value was determined by titration (with 0.1N HClO4 in acetic acid against crystal violet).
Liquid chromatography (UHPLC) was carried out for quantitative determination of N-benzylethane-1,2-diamine after derivatization with phenyl isocyanate against external calibration.
Gel-permeation chromatography (GPC) was carried out for determination of the weight ratios between 2:1 adduct, 3:2 adduct and >3:2 adduct against polystyrene as a standard.
Araldite® GY 250: Bisphenol A diglycidyl ether, EEW 187 g/equiv. (from Huntsman)
Araldite® DY-E: Monoglycidyl ethers of C12 to C14 alcohols, EEW approx. 290 g/equiv. (from Huntsman)
B-EDA mix Amine mixture containing approx. 85% by weight of N-benzylethane-1,2-diamine and approx. 14% by weight of N,N′-dibenzylethane-1,2-diamine, prepared as described below, AHEW 55 g/equiv.
B-EDA pure Purified N-benzylethane-1,2-diamine, prepared as described below, 150.2 g/mol, AHEW 50 g/equiv.
DB-EDA N,N′-Dibenzylethane-1,2-diamine, 240.4 g/mol, AHEW 120.2 g/equiv. (from Sigma Aldrich)
IPDA 3-Aminomethyl-3,5,5-trimethylcyclohexylamine, AHEW 42.6 g/equiv. (Vestamin® IPD from Evonik)
Amine mixture containing N-benzylethane-1,2-diamine and N,N′-dibenzylethane-1,2-diamine (B-EDA mix):
A round-bottomed flask was charged with 180.3 g (3 mol) of ethane-1,2-diamine under a nitrogen atmosphere at room temperature. A solution of 106.1 g (1 mol) of benzaldehyde in 1200 ml of isopropanol was slowly added dropwise while stirring well and stirring was continued for a further 2 hours. The reaction mixture was then hydrogenated in a continuous hydrogenation apparatus with a Pd/C fixed-bed catalyst at a hydrogen pressure of 80 bar, a temperature of 80° C., and a flow rate of 5 ml/min. To monitor the reaction, IR spectroscopy was used to check whether the imine band at approx. 1665 cm−1 had disappeared. The hydrogenated solution was then concentrated on a rotary evaporator at 65° C., removing unreacted ethane-1,2-diamine, water, and isopropanol. The reaction mixture thus obtained was a clear, pale yellowish liquid having an amine value of 678 mg KOH/g and containing approx. 85% by weight of N-benzylethane-1,2-diamine (retention time 8.47-8.57 min) and approx. 14% by weight of N,N′-dibenzylethane-1,2-diamine (retention time 14.27 min), as determined by GC. This corresponds to a weight ratio between N-benzylethane-1,2-diamine and N,N′-dibenzylethane-1,2-diamine of 86/14.
N-Benzylethane-1,2-diamine (purified, B-EDA pure): 50 g of the amine mixture comprising N-benzylethane-1,2-diamine and N,N′-dibenzylethane-1,2-diamine (B-EDA-mix) prepared as described was distilled under reduced pressure at 80° C., resulting in 31.3 g of distillate (N-benzylethane-1,2-diamine) being collected at a vapor temperature of 60 to 65° C. and 0.06 mbar. A colorless liquid having a viscosity of 8 mPa·s at 20° C., an amine value of 750 mg KOH/g and a purity, determined by GC, of >97% was obtained.
53.0 g of the amine mixture B-EDA-mix (containing 0.3 mol of N-benzylethane-1,2-diamine and 0.03 mol of N,N′-dibenzylethane-1,2-diamine), prepared as described above, was initially charged under a nitrogen atmosphere and heated to 80° C. To this was slowly added 36.8 g (0.2 mol of epoxy groups) of Araldite® GY 250 while stirring well, with the temperature of the reaction mixture maintained between 70 and 90° C. by cooling. The reaction mixture was held within this temperature range for one hour and then cooled. A clear, slightly yellowish liquid having a viscosity at 20° C. of 74 Pa.s and a calculated AHEW of 117 g/equiv. was obtained. The adduct A1 contained 27.8% by weight of N-benzylethane-1,2-diamine according to UHPLC, the adduct molecules being in the weight ratio 2:1 adducts/3:2 adducts/>3:2 adducts=46.5/27.2/26.3 according to GPC.
45.0 g (0.3 mol) of purified N-benzylethane-1,2-diamine (B-EDA pure) prepared as described above and 11.3 g (0.05 mol) of N,N′-dibenzylethane-1,2-diamine (DB-EDA) were initially charged under a nitrogen atmosphere, mixed, and heated to 80° C. To this was slowly added 36.8 g (0.2 mol of epoxy groups) of Araldite® GY 250 while stirring well, with the temperature of the reaction mixture maintained between 70 and 90° C. by cooling. The reaction mixture was held within this temperature range for one hour and then cooled. A clear, slightly yellowish liquid having a viscosity at 20° C. of 47 Pa.s and a calculated AHEW of 117.3 g/equiv. was obtained.
45.0 g (0.3 mol) of purified N-benzylethane-1,2-diamine (B-EDA pure) prepared as described above and 19.3 g (0.08 mol) of N,N′-dibenzylethane-1,2-diamine (DB-EDA) were initially charged under a nitrogen atmosphere, mixed, and heated to 80° C. To this was slowly added 36.8 g (0.2 mol of epoxy groups) of Araldite® GY 250 while stirring well, with the temperature of the reaction mixture maintained between 70 and 90° C. by cooling. The reaction mixture was held within this temperature range for one hour and then cooled. A clear, slightly yellowish liquid having a viscosity at 20° C. of 19 Pa.s and a calculated AHEW of 117.5 g/equiv. was obtained.
45.0 g (0.3 mol) of purified N-benzylethane-1,2-diamine (B-EDA pure) prepared as described above was initially charged under a nitrogen atmosphere and heated to 80° C. To this was slowly added 36.8 g (0.2 mol of epoxy groups) of Araldite® GY 250 while stirring well, with the temperature of the reaction mixture maintained between 70 and 90° C. by cooling. The reaction mixture was held within this temperature range for one hour and then cooled. A clear, slightly yellowish liquid having a viscosity at 20° C. of 262 Pa.s and a calculated AHEW of 116.3 g/equiv. was obtained.
The adduct A4 contained 24.2% by weight of N-benzylethane-1,2-diamine according to UHPLC, the adduct molecules being in the weight ratio 2:1 adducts /3:2 adducts/>3:2 adducts=42.5/27.0/30.5 according to GPC.
For each example, the ingredients of the resin component specified in Tables 1 to 3 were mixed in the specified amounts (in parts by weight) using a centrifugal mixer (SpeedMixer™ DAC 150, FlackTek Inc.) and stored with the exclusion of moisture.
The ingredients of the curing agent component specified in Tables 1 to 3 were likewise processed and stored.
The two components of each composition were then processed using the centrifugal mixer into a homogeneous liquid and this was tested immediately as follows:
10 minutes after mixing, the viscosity was measured at 20° C. (“Viscosity (10′)”). The gel time was determined in standard climatic conditions by agitating the mixed composition (25 g) with a spatula from time to time until it began to gel. For determination of Shore D hardness in accordance with DIN 53505, two cylindrical test specimens (diameter 20 mm, thickness 5 mm) were in each case produced. One was stored under standard climatic conditions and the hardness measured after 1 day and after 2 days (1 d SCC and 2d SCC); the other was stored at 8° C. and 80% relative humidity and the hardness measured after 1 day and after 2 days in the cold state (1d 8°/80% and 2d 8°/80%).
A first film was applied to a glass plate in a layer thickness of 500 μm, and this was stored/cured under standard climatic conditions. The König hardness (König pendulum hardness, measured in accordance with DIN EN ISO 1522) was determined on this film after 1 day (“König hardness (1 d SCC)”), after 2 days (“König hardness (2d SCC)”), after 4 days (“König hardness (4d SCC)”), after 7 days (“König hardness (7d SCC)”), and after 14 days (“König hardness (14d SCC)”). Once values of more than 200 s had been attained, the König hardness was not determined again. After 14 days, the appearance of the film was assessed (designated “Appearance (SCC)” in the table). A film was described as “nice” if it had a glossy and nontacky surface with no structure. “Structure” refers to any kind of marking or pattern on the surface.
A second film was applied to a glass plate in a layer thickness of 500 μm and this was immediately after application stored/cured for 7 days at 8° C. and 80% relative humidity and then for 2 weeks under standard climatic conditions. 24 hours after application, a polypropylene bottle top beneath which a damp sponge had been positioned was placed on the film. After a further 24 hours, the sponge and the bottle top were removed and positioned at a new point on the film, from which it was in turn removed and repositioned after 24 hours, this being done a total of 4 times. The appearance of this film was then assessed (designated “Appearance (8°/80%)” in the tables) in the same way as described for Appearance (SCC). Also reported in each case here was the number and nature of visible marks that had formed in the film as a result of the damp sponge and/or the bottle top on top. The number of white-colored spots was reported as “blushing”. A faint white discolored spot was designated as “(1)”. The designation “ring” was reported if a ring-shaped imprint was present due to sinking of the first bottle top applied 24 hours after application. Such a ring-shaped impression indicates that the coating was not ready to be walked on. The König hardness was again determined on the films thus cured, in each case after 7 days at 8° C. and 80% relative humidity (“König hardness (7d 8°/80%)”), then after a further 2 days under SCC (“König hardness (+2d SCC)”), 7 days under SCC (“König hardness (+7d SCC)”), and 14 d under SCC (“König hardness (+14d SCC)”). Once values of more than 190 s had been attained, the König hardness was not determined again.
As a measure of yellowing, the change in color after stressing in a weathering tester was also determined. For this, a further film was applied to a glass plate in a layer thickness of 500 μm and this was stored/cured under standard climatic conditions for 2 weeks and then stressed for 72 hours at a temperature of 65° C. in a model Q-Sun Xenon Xe-1 weathering tester having a Q-SUN Daylight-Q optical filter and a xenon lamp having a light intensity of 0.51 W/m2 at 340 nm (Q-Sun (72 h)). The difference in color ΔE of the stressed film versus the corresponding unstressed film was then determined using an NH310 colorimeter from Shenzen 3NH Technology Co. LTD equipped with silicon photoelectric diode detector, light source A, color space measurement interface CIE L*a*b*C*H*. AE values up to 5 represent slight yellowing.
The results are reported in Tables 1 to 3.
The examples designated “(Ref.)” are comparative examples.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20158929.8 | Feb 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/054252 | 2/22/2021 | WO |
