Description:
Are you interested in learning more about dimethyl urea hardeners? Contact us today to secure an expert consultation!
The use of epoxy resins is widespread, owing to their outstanding properties such as, for example, high impact strength and abrasion resistance and good chemical stability, and finds use in numerous sectors. Epoxy resins exhibit outstanding adhesiveness and electrical insulation capacity. They serve, for example, as a matrix for fiber composites, in the context, for example, of the building of wind power installations, and as structural components in the air travel sector. In electronics they are employed as electrical laminates in printed circuit boards. Furthermore, they are widespread in use as structural adhesives, as casting varnishes, and as powder coating resins.
The curing of epoxy resins proceeds in accordance with a variety of mechanisms. Besides curing with phenols or anhydrides, curing with amines is described very frequently for the crosslinking of the epoxide groups. The stoichiometric amount of hydrogen atoms is added, as may be supplied, for example, by bifunctional amines. A further mechanism describes the reaction of an initiator or accelerator with epoxide groups, forming a highly reactive intermediate which is able to react with further epoxide groups without the need for further crosslinkers. The initiators may also lower the activation energy of the reaction of crosslinker or hardener molecules, so that the curing temperatures are lowered considerably. Compounds which have these properties are, in general, tertiary amines, imidazoles or else substituted ureas, which have the ability, for example, to reduce the cure temperature of dicyandiamide.
Usually the individual components of epoxy resin formulations are not mixed together until immediately before curing and heating, in order to prevent premature reaction. In this case the resin and, separately therefrom, a mixture of hardener and accelerator are combined and then reacted by heating. A disadvantage of these two component mixtures is a relatively short pot life, i.e., a relatively short time within which the mixture can be processed. Likewise, errors in mixing may lead to inhomogeneous products and hence to unsatisfactory results. One-component mixtures include, besides resin and further constituents (such as fillers, thixotroping agents, pigments, etc.), a hardener which is latent at room temperature, and they have a significantly longer pot life and require, for their curing, elevated temperatures, in particular above 1 00° C, and usually longer cure times. A typical example of a latent hardener is dicyandiamide (cf. EP 148 365 A1, U.S. Pat. No. 2,637,715 B1). In order to overcome these disadvantages, chemically latent accelerators are added to such one-component mixtures, with reductions in storage stability and processing time being accepted, in order to lower the temperature of curing. Examples of latent accelerators of this kind include, in particular, urons, such as 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) (cf. GB 1,153,639 A1, GB 1,293,142 A1, U.S. Pat. No. 3,386,956 B1, U.S. Pat. No. 6,231,959 B1). These compounds are usually 1,1-dialkyl-3-arylureas, where the aromatic may be substituted or unsubstituted, or else is hydrogenated. At elevated temperatures these compounds release dimethylamine and the aryl isocyanate, which synergistically accelerate the curing reaction with dicyandiamide. Hence it is possible to effect curing at significantly lower temperatures. The temperature at which this dissociation of the uron begins, and hence at which the crosslinking reaction commences, depends on the nature of the substituents. At the same time it is found that, the lower the temperature at which curing commences, the lower, too, is the stability of such a mixture at temperatures below the cure temperature.
The aryl-substituted urons employed to date have only a limited stability in the mixture; in other words, there continues to be a need for new accelerators which have the capacity for long storage stability and processing stability in combination with high reactivity. Additionally the mechanical properties of the cured polymer ought not to be substantially impaired as a result of the addition of the accelerator.
Many of the compounds employed as latent accelerators exhibit inadequate solubility in common solvents, thereby significantly reducing their spectrum of application, particularly in sectors in which a uniform reaction is needed. Some of the uron accelerators employed are halogen-substituted, which also limits their use in the electronics sector.
It was an object of the present invention, therefore, to provide latent accelerators for epoxy resin systems that do not have the stated disadvantages of the prior art. By latent accelerators are meant additives to a resin/hardener mixture that as far as possible do not lower the pot life, i.e., the time within which the mixture can be processed, and at the same time accelerate the reactivity, i.e., the crosslinking at elevated temperature. Compounds are desired, therefore, which allow a processing duration which is as long as possible. The accelerators of the invention for epoxy resin systems ought, consequently, to possess a high reactivity and very good storage stability at room temperature and at temperatures below the cure temperatures and ought, furthermore, as far as possible to be halogen-free and toxicologically unobjectionable.
This object has been achieved in accordance with the invention by using as accelerators asymmetrically substituted urea derivatives of the general formula (I)
where R1 and R2 each independently are a linear or branched aliphatic hydrocarbon radical having 1 to 4 carbon atoms.
R1 and R2 may be, for example, methyl, ethyl, propyl and butyl. Examples of such urea derivatives are, for example, N,N-diethylurea, N,N-dipropylurea, N,N-ethyl-methylurea and N,N-dimethylurea. A preferred urea derivative is N,N-dimethylurea.
It has surprisingly been found that the accelerators proposed in accordance with the invention not only have a very good reactivity and storage stability but also exert no negative effect whatsoever on the mechanical properties of the cured material.
It is true that the use of dimethylurea as an accelerator in combination with dicyandiamide is recommended by JP-A 79-26000 for urethane-modified epoxy resin systems; however, the storage stabilities in those formulations are only comparable with those achieved using (1,1′-methylenedi-p-phenylene)bis(3,3-dimethylurea) (=MDI uron). Surprisingly, with the asymmetrically substituted urea derivatives in the epoxy resin systems claimed in accordance with the invention, it has been possible to obtain substantially better storage stabilities than is possible with MDI uron.
Additionally, JP-A 81-133856, which describes the combination of N,N-dimethylurea with phenol novolaks as hardeners for epoxy resin systems in the semiconductor systems sector, contains no indication of the influence of N,N-dimethylurea on the storage stability of the corresponding epoxy resin formulations.
In accordance with the invention accelerators used in combination with dicyandiamide as latent hardener are asymmetrically substituted urea derivatives of the general formula (I)
where R1 and R2 each independently are a linear or branched aliphatic hydrocarbon radical having I to 4 carbon atoms. Suitable in this context are methyl, ethyl, propyl, and butyl radicals, which may be linear or else, where appropriate, may be branched. Examples of urea derivatives of the invention are, N,N-dimethylurea, N,N-diethylurea, N,N-dipropylurea, and N,N-ethylmethylurea. The urea derivative N,N-dimethylurea is used with preference.
It is regarded as being essential to the invention that the inventively proposed combination of asymmetrically substituted urea derivatives and dicyandiamide are used for the following epoxy resin systems: epoxy resins based on unhalogenated or halogenated bisphenols of type A or F and also based on resorcinol or tetrakisphenylolethane.
Epoxy resins based on bisphenol A and F are used predominantly in the sector of fiber composites, of adhesives, and also, in relatively high molecular mass form, as solid resins in powder coating materials.
In the sector of electrical laminates the cured epoxy resin is expected to exhibit particular flame retardance and high temperature stability. For this purpose use is made predominantly of halogenated systems of bisphenol A, examples being tetrabromobisphenol A derivatives or trifluoromethyl-substituted versions thereof.
Particularly flame-retardant composites are produced, for example with epoxy resins based on resorcinol and tetrakisphenylolethane.
The proportions of dicyandiamide and urea derivative relative to the corresponding epoxy resin may be varied within wide limits. It has, however, proven particularly advantageous to use the dicyandiamide in an amount of about 1% to 15%, preferably about 2% to 12%, more preferably about 2% to 8%, by weight based on the epoxy resin. The urea derivative is used in an amount of about 0.5% to 15%, preferably about 1% to 12%, by weight based on the epoxy resin. A particularly preferred amount is about 1% to 10% by weight based on the epoxy resin.
According to one preferred embodiment the urea derivative and the dicyandiamide are employed in a very finely divided form, the components having a preferred average particle size of about 0.5 to 100 μm, in particular about 10 to 50 μm, more preferably about 2 to 10 μm. The curing reaction of the inventively proposed accelerators and hardeners with the respective epoxy resins can be carried out in accordance with the customary methods, with curing being carried out at temperatures between about 70 and 220° C., in particular between about 80 and 160° C.
The inventively claimed combination of urea derivative as accelerator and dicyandiamide as latent hardener is outstandingly suitable, for example, for the hot curing of epoxy resin in the sector of fiber composites, powder coatings, electrical laminates and adhesives.
The advantages of the accelerator/hardener combination of the invention are the excellent reactivity and very good storage stability. Surprisingly, the mechanical properties of the resins cured accordingly, as well, are likewise outstanding and are comparable with those of the blocked accelerators UR 200 (diuron) and UR 300 (fenuron) which have already been employed.
On the basis of these very good performance properties and a low toxicity, the inventively proposed hardener/accelerator systems are outstandingly suitable for technical use.
The examples which follow are intended to illustrate the invention.
The following products and materials were used in the examples:
Epoxy Resins:
Epikote 828 (Resolution): bisphenol A resin, EEW 185
DER 664 UE (Dow): solid resin, EEW 910 (resin)
Hardener:
Dyhard 100 S (Degussa): micronized dicyandiamide, particle size 98% <10 μm, 50% approx. 2.5 μm (Dyh 100 S)
Accelerators:
Dyhard UR 200 (Degussa): micronized diuron or 3-(3,4-dichlorophenyl)-1,1-dimethylurea, particle size 98% <10 μm, 50% approx. 2.5 μm (UR 200)
Dyhard UR 300 (Degussa): micronized fenuron or 3-phenyl-1,1-dimethylurea, particle size 98% <10 μm, 50% approx. 2.5 μm (UR 300)
Dyhard UR 500 (Degussa): micronized TID uron or toluylbis-1,1-dimethylurea, particle size 98% <10 μm, 50% approx. 2.5 μm (UR 500)
Dyhard MIA 5 (Degussa): micronized adduct of methylimidazole with bisphenol A resin (Epikote 828), particle size 98% <70 μm
N,N-dimethylurea or 1,1-dimethylurea (Merck): ground in the laboratory, particle size 98% <10 μm, 50% approx. 2.5 μm (1,1-DMH)
N,N-diethylurea or 1,1-diethylurea (Merck): ground in the laboratory, particle size 98% <10 μm, 50% approx. 2.5 μm (1,1-DER)
MDI uron, (1,1′-methylenedi-p-phenylene)bis(3,3-dimethylurea), was prepared by known methods from MDI (1,1′-methylenedi-p-phenylene) diisocyanate and dimethylamine (e.g., EP 402 020 A1, CS 233 068 B1) and subsequently ground in the laboratory, particle size 98% <10 μm, 50% approx. 2.5 μm
Additive:
Lanco Wax TPS 040 (Lubrizol), micronized in the laboratory 98% <80 μm
5 g in each case of a formulation, corresponding to the composition in the second column from the left in Table I (“Components”), made up of bisphenol A resin (Epikote 828, EEW 185), Dyhard 100 S as hardener, and inventive accelerator 1,1-dimethylurea (1,1-DMH) or 1,1-diethylurea (1,1-DEH), and also as a comparison thereto, formulations which correspond to the compositions of the second column from the left in Table 2 (“Components”) and which include the noninventive standard uron accelerators Dyhard UR 200 (diuron) and UR 300 (fenuron), were produced. A measurement was made in each case of the gel time at the stated temperature and the reactivity was determined by means of DSC.
As the temperature program for determining the peak temperature (DSC peak), heating took place at a rate of 10° C./min from 30 to 350° C. The onset of reaction (DSC onset) was determined from the same measurement by applying the tangent to the reaction peak.
TABLE 1 DSC DSC Gel time at Gel time at Expt. Components (parts by wt.) (peak) (onset) 150° C. 120° C. Tg 1.1 Resin:Dyh100S:1,1-DMH 163, 7° C. 153, 2° C. 3 min. 33 sec. 28 min 140, 3° C. 100:6:1 1.2 Resin:Dyh100S:1,1-DMH 154, 6° C. 142, 4° C. 2 min. 40 sec. 13 min. 30 sec. 127, 1° C. 100:6:3 1.3 Resin:Dyh100S:1,1-DMH 150, 8° C. 137, 2° C. 2 min. 01 sec. 10 min. 120, 3° C. 100:6:5 1.4 Resin:Dyh100S:1,1-DEH 180, 3° C. 171, 2° C. 10 min. 07 sec. 56 min. 152, 4° C. 100:6:1 1.5 Resin:Dyh100S:1,1-DEH 174, 5° C. 165, 1° C. 6 min. 28 sec. 35 min. 131, 8° C. 100:6:3 1.6 Resin:Dyh100S:1,1-DEH 170, 7° C. 160, 5° C. 5 min. 13 sec. 28 min. 118, 0° C. 100:6:5For determining the glass transition temperature (Tg) the material from the gel time determination at 120° C. was employed. The formulation was fully cured by heating to 200° C. (temperature program: 30 to 200° C., heating rate 20° C./min) and maintaining this temperature for 30 minutes. After cooling to room temperature (RT) the sample was heated from 30 to 200° C. with a heating rate of 10° C./min, and the Tg determined therefrom.
TABLE 2 Examples (not inventive): DSC DSC Gel time at Gel time at Expt. Components (parts by wt.) (peak) (onset) 150° C. 120° C. Tg 1.7 Resin:Dyh100S:UR200 160, 7° C. 151, 1° C. 2 min. 47 sec. 12 min. 150, 4° C. 100:6:1 1.8 Resin:Dyh100S:UR200 154, 0° C. 145, 9° C. 2 min. 06 sec. 8 min. 134, 7° C. 100:6:3 1.9 Resin:Dyh100S:UR200 150, 9° C. 143, 5° C. 1 min. 57 sec. 7 min. 123, 2° C. 100:6:5 1.10 Resin:Dyh100S:UR300 157, 6° C. 149, 3° C. 2 min. 23 sec. 12 min. 146, 2° C. 100:6:1 1.11 Resin:Dyh100S:UR300 152, 1° C. 144, 9° C. 1 min. 51 sec. 7 min. 30 sec. 130, 7° C. 100:6:3 1.12 Resin:Dyh100S:UR300 148, 8° C. 142, 0° C. 1 min. 51 sec. 5 min. 30 sec. 118, 4° C. 100:6:5Comparing the two Tables 1 and 2 it is apparent that the reactivity of the 1,1-dimethylurea acting as accelerator is entirely comparable with that of the standard accelerators of the uron series. This is also true, to a somewhat lesser extent, for the 1,1-diethylurea. The glass transition temperature of the material cured with dialkylurea accelerators, as well, is within the range of the values achievable with the standard accelerators Dyhard UR 200 and UR 300. Particularly when relatively large amounts of accelerator are added, the tendency toward Tg reduction in the case of the materials of the invention is less strongly pronounced.
Latency Experiments:
TABLE 3 Storage 1 part by wt. 3 parts by wt. 5 parts by wt. 1 part by wt. 3 parts by wt. 5 parts by wt. period at 1,1-DMH 1,1-DMH 1,1-DMH MDI uron MDI uron MDI uron Expt. 40° C. (d) (Pa*s) (Pa*s) (Pa*s) (Pa*s) (Pa*s) (Pa*s) 2.1 0 43 45 47 51 72 89 2.2 4 40 43 50 53 57 58 2.3 8 37 43 47 63 68 76 2.4 11 38 43 49 72 88 96 2.5 15 42 41 50 102 117 130 2.6 18 46 51 53 2.7 22 54 49 62 212 347 508 2.8 25 55 58 56 solid solid solid 2.9 29 67 64 61 2.10 32 63 66 60 2.11 39 87 73 81 2.12 43 160 102 101 2.13 46 217 133 106 2.14 50 545 143 116 2.15 53 618 190 137 2.16 57 solid 348 230 2.17 60 421 298 2.18 64 solid 445 2.19 67 471A formulation of 100 parts by weight of bisphenol A epoxy resin (Epikote 828, EEW 185) and 6.5 parts by weight of Dyhard 100 S was admixed in each case with the amounts of latent accelerators indicated in Tables 3 and 4. After the stated storage period at the respective temperature (40° C. or 23° C.) a measurement was made in each case of the viscosity, using a Haake viscometer. The viscosity values are shown in columns 3-8 of Tables 3 and 4.
TABLE 4 Storage 1 part by wt. 3 parts by wt. 5 parts by wt. 1 part by wt. 3 parts by wt. 5 parts by wt. period at 1,1-DMH 1,1-DMH 1,1-DMH MDI uron MDI uron MDI uron Expt. 23° C. (d) (Pa*s) (Pa*s) (Pa*s) (Pa*s) (Pa*s) (Pa*s) 2.20 0 43 45 47 52 73 85 2.21 6 45 48 51 83 90 96 2.22 13 52 55 59 105 125 125 2.23 20 50 57 63 148 180 182 2.24 28 66 67 86 solid solid solid 2.25 35 66 74 106 2.26 41 111 119 124 2.27 48 157 182 234 2.28 55 186 solid solid 2.29 62 234As is clearly apparent from Table 3, the formulations of the invention have considerably better properties with regard to latency: while a doubling of the viscosity occurs in formulations with MDI uron at 40° C. after only 15 days, with 1,1-dimethylurea this is the case only after approximately 40 days. For MDI uron the processability of the formulation is below 25 days, while for formulations with 1,1-dimethylurea it is more than twice as high (more than 50 days).
The processability of the formulations comprising 1,1-dimethylurea is likewise considerably higher at room temperature than in formulations with MDI uron.
Comparison of N,N-dimethylurea With Various Standard Accelerators (MDI Uron, UR 300 and UR 500):
TABLE 5 3 parts by wt. 3 parts by wt. Storage period 1,1-DMH MDI uron 3 parts by wt. 3 parts by wt. Expt. at 40° C. (d) (Pa*s) (Pa*s) UR 300 (Pa*s) UR 500 (Pa*s) 3.1 0 45 72 45 52 3.2 4 43 57 52 120 3.3 8 43 68 solid solid 3.4 11 43 88 3.5 15 41 117 3.6 18 51 3.7 22 49 347 3.8 25 58 solid 3.9 29 64 3.10 32 66 3.11 39 73 3.12 43 102 3.13 46 133 3.14 50 143 3.15 53 190 3.16 57 348 3.17 60 421 3.18 64 solidFormulations are produced which are composed in each case of 100 parts by weight of bisphenol A epoxy resin (Epikote 828, EEW 185), 6.5 parts by weight of Dyhard 100 S, and the amount of the respective accelerator indicated in Table 5. After the storage period at 40° C. indicated in the second column, the viscosity was determined in each case, using a Haake viscometer. The viscosity values are shown in columns 3-6 of Table 5.
In comparison with standard accelerators of the uron series the advantage of using 1,1-dimethylurea in one-component mixtures becomes even more distinct: while the standard products UR 300 and UR 500 can be processed only for up to I week at 40° C., a formulation with MDI uron can be processed for at least 3 weeks. The formulation comprising dimethylurea, indeed, can be processed for 7 to 8 weeks.
Powder Coating Examples:
TABLE 6 A B C D DER 664UE, EEW 910 180 g 180 g 180 g 180 g TiO2 90 g 90 g 90 g 90 g Lanco Wax TPS-040 3 g 3 g 3 g 3 g Dicyandiamide 6 g Dyhard 100 S 9 g 9 g 9 g Dyhard UR 300 — — 4.5 g — Dyhard UR 500 4.5 g — — — 1,1-DMH — 4.5 g — Dyhard MIA 5 1.5 gFormulations A, B, C and D below, consisting of the components indicated in Table 6, were compared with one another:
The formulations were each extruded at 95° C.
TABLE 7 A A B B C C D D 180° C. 200° C. 180° C. 200° C. 180° C. 200° C. 180° C. 200° C. Film thickness 78 73 80 82 83 77 65 66 (μm) Leveling good good good good good good orange orange peel peel Gloss (60°) 73.2 72.7 61 63.2 67.1 68.1 84.6 93.4 Whiteness 89 85.3 90.3 89.3 90.8 89.5 85.5 80.8 Yellowness −0.52 3.7 −1.6 0.44 −1.9 −0.54 2.1 7 Erichsen mm 8.4 7.2 8.4 8.3 8.4 8.4 8.4 8.4 Mandrel <5 <5 <5 <5 <5 <5 <5 <5 bending mm Ball impact 120 120 120 120 120 120 120 120 inchFor the production of the corresponding powder coating materials, the raw materials in powder form were each premixed, extruded for better homogenization at 95° C., then ground, and subsequently applied by spray gun to steel plates in film thicknesses of between 60 to 80 μm and cured or crosslinked at two different temperatures (180 and 200° C.). The results of the tests on the cured powder coating formulations are depicted in Table 7.
The mechanical properties of the accelerators of the invention in powder coating formulations are absolutely comparable with those of the prior-art methylimidazole adduct (Dyhard MIA 5), with at the same time a lower yellowing tendency and better leveling properties.
Die Verwendung von Epoxidharzen ist aufgrund ihrer hervorragenden Eigenschaften wie hohe Schlagzähigkeit und Abriebfestigkeit und guter Chemikalienbeständigkeit sehr weit verbreitet und findet in vielen Bereichen Verwendung. Sie zeigen hervorragende Haftfähigkeit und elektrisches Isolationsvermögen. Sie dienen als Matrix für Faserverbundstoffe, z. B. beim Bau von Windkraftanlagen und im Luftfahrtbereich als strukturelle Komponenten. In der Elektronik kommen sie als Elektrolaminate in Leiterplatten zum Einsatz. Darüber hinaus sind sie weit verbreitet im Einsatz als Strukturklebstoffe, als Gießlacke und als Pulverlackharze.The Use of epoxy resins is due to their excellent properties like high impact strength and abrasion resistance and good chemical resistance very widespread and is used in many areas. They show excellent adhesiveness and electrical insulation. They serve as a matrix for Fiber composites, eg. B. in the construction of wind turbines and in the aviation sector as structural components. In electronics they come as electric laminates used in printed circuit boards. In addition, they are widely used in use as structural adhesives, as casting varnishes and as powder coating resins.
Die Härtung von Epoxidharzen verläuft nach verschiedenen Mechanismen. Neben der Härtung mit Phenolen oder Anhydriden wird sehr häufig die Härtung mit Aminen zur Vernetzung der Epoxidgruppen beschrieben. Dabei wird die stöchiometrische Menge Wasserstoffatome, wie sie z. B. bifunktionelle Amine liefern können, zugesetzt. Ein weiterer Mechanismus beschreibt die Reaktion eines Initiators oder Beschleunigers mit Epoxidgruppen, wobei ein hochreaktives Zwischenprodukt gebildet wird, welches mit weiteren Epoxidgruppen reagieren kann, ohne dass weitere Vernetzer notwendig sind. Die Initiatoren können auch die Aktivierungsenergie der Reaktion von Vernetzer- oder Härtermolekülen erniedrigen, so dass die Härtungstemperaturen erheblich herabgesetzt werden. Verbindungen, welche diese Eigenschaften aufweisen, sind allgemein tertiäre Amine, Imidazole oder auch substituierte Harnstoffe, welche die Härtungstemperatur von Dicyandiamid herabsetzen können.The hardening of epoxy resins according to different mechanisms. In addition to curing with phenols or anhydrides becomes very common the hardening described with amines for crosslinking the epoxy groups. It will the stoichiometric Amount of hydrogen atoms, as z. B. can provide bifunctional amines added. Another mechanism describes the reaction of an initiator or accelerator with epoxide groups, wherein a highly reactive intermediate is formed, which can react with other epoxide groups, without the need for further crosslinkers. The initiators can also decrease the activation energy of the reaction of crosslinker or hardener molecules, so that the curing temperatures be significantly reduced. Compounds which have these properties are generally tertiary amines, Imidazoles or substituted ureas, which are the curing temperature of dicyandiamide.
Üblicherweise werden die Einzelkomponenten von Epoxidharz-Formulierungen erst unmittelbar vor dem Härten und Erwärmen zusammengemischt, um eine vorzeitige Reaktion zu verhindern. Hierbei werden das Harz und getrennt hiervon eine Mischung aus Härter und Beschleuniger zusammen gegeben und anschließend durch Erwärmen zur Reaktion gebracht. Ein Nachteil dieser Zweikomponentengemische ist eine relativ kurze Topfzeit, d. h. eine relativ kurze Zeit, in der das Gemisch verarbeitet werden kann. Ebenfalls können Fehler beim Mischen zu inhomogenen Produkten und damit zu unbefriedigenden Ergebnissen führen. Einkomponentenmischungen enthalten neben Harz und weiteren Bestandteilen (wie Füllstoffe, Thixotropisierungsagentien, Pigmente usw.) einen bei Raumtemperatur latenten Härter, haben eine deutlich längere Topfzeit und benötigen zum Aushärten erhöhte Temperaturen, insbesondere über 100 °C und meist längere Härtungszeiten. Ein typisches Beispiel für einen latenten Härter stellt Dicyandiamid dar (vgl. EP 148 365 A1 , US 2,637,715 B1 ). Um diese Nachteile zu überwinden, werden solchen Einkomponentengemischen chemisch latente Beschleuniger zugesetzt, bei denen Verkürzungen der Lagerstabilität und der Verarbeitungszeit in Kauf genommen werden, um die Temperatur des Aushärtens herabzusetzen. Solche latenten Beschleuniger sind insbesondere Urone, wie z. B. 3-(3,4-Dichlorphenyl)-1,1-dimethylharnstoff (Diuron) (vgl. GB 1,153,639 A1 , GB 1,293,142 A1 , US 3,386,956 B1 , US 6,231,959 B1 ). Bei diesen Verbindungen handelt es sich üblicherweise um 1,1-Dialkyl-3-arylharnstoffe, wobei der Aromat substituiert oder unsubstituiert sein kann, oder aber hydriert ist. Bei erhöhten Temperaturen setzen diese Verbindungen Dimethylamin und das Arylisocyanat frei, welche die Härtungsreaktion mit Dicyandiamid synergistisch beschleunigen. Damit kann bei deutlich niedrigeren Temperaturen ausgehärtet werden. Die Temperatur, bei welcher diese Dissoziation des Urons einsetzt und somit die Vernetzungsreaktion beginnt, hängt von der Art der Substituenten ab. Gleichzeitig findet man, dass je niedriger die Temperatur ist, bei der die Aushärtung beginnt, desto geringer ist auch die Stabilität einer solchen Mischung bei Temperaturen unterhalb der Härtungstemperatur.Usually, the individual components of epoxy resin formulations are mixed together just prior to curing and heating to prevent premature reaction. Here, the resin and separately from a mixture of hardener and accelerator are added together and then brought to reaction by heating. A disadvantage of these two-component mixtures is a relatively short pot life, ie a relatively short time in which the mixture can be processed. Also, errors in mixing can lead to inhomogeneous products and thus to unsatisfactory results. One-component mixtures contain, in addition to resin and other constituents (such as fillers, thixotropic agents, pigments, etc.) a latent curing at room temperature, have a significantly longer pot life and require for curing elevated temperatures, especially above 100 ° C and usually longer curing times. A typical example of a latent hardener is dicyandiamide (cf. EP 148 365 A1 . US 2,637,715 B1 ). To overcome these drawbacks, chemically latent accelerators are added to such one-component blends where reductions in storage stability and processing time are taken into account to lower the cure temperature. Such latent accelerators are especially urons, such as. B. 3- (3,4-dichlorophenyl) -1,1-dimethylurea (diuron) (see. GB 1,153,639 A1 . GB 1,293,142 A1 . US 3,386,956 B1 . US 6,231,959 B1 ). These compounds are usually 1,1-dialkyl-3-aryl ureas, wherein the aromatic may be substituted or unsubstituted, or else hydrogenated. At elevated temperatures, these compounds release dimethylamine and the aryl isocyanate, which synergistically accelerate the curing reaction with dicyandiamide. This can be cured at much lower temperatures. The temperature at which this dissociation of the uron starts, thus initiating the crosslinking reaction, depends on the nature of the substituents. At the same time it is found that the lower the temperature at which the cure begins, the lower the stability of such a mixture at temperatures below the cure temperature.
Die bisher eingesetzten arylsubstituierten Urone weisen nur eine begrenzte Stabilität in der Mischung auf, d. h. es besteht weiter Bedarf an neuen Beschleunigern, welche die Fähigkeit langer Lager- und Verarbeitungsstabilität in Kombination mit hoher Reaktivität vereinen. Zusätzlich dürfen die mechanischen Eigenschaften des ausgehärteten Kunststoffs durch den Zusatz des Beschleunigers nicht wesentlich verschlechtert werden.The previously used aryl-substituted urones have only a limited stability in the mixture, d. H. there is still a need for new accelerators, which the ability long storage and processing stability in combination with high Reactivity combine. additionally allowed the mechanical properties of the cured plastic through the Addition of the accelerator can not be significantly deteriorated.
Viele der Verbindungen, die als latente Beschleuniger eingesetzt werden, zeigen eine nicht ausreichende Löslichkeit in gebräuchlichen Lösemitteln, womit das Anwendungsspektrum deutlich verringert ist, insbesondere für Bereiche, in denen ein gleichmäßige Reaktion notwendig ist. Einige der eingesetzten Uron-Beschleuniger sind halogensubstituiert, was ihre Anwendung im Elektronikbereich einschränkt.Lots the compounds used as latent accelerators show insufficient solubility in common Solvents whereby the range of applications is significantly reduced, in particular for areas, in which a steady reaction necessary is. Some of the Uron accelerators used are halogen-substituted, which limits their application in the electronics sector.
Der vorliegenden Erfindung lag daher die Aufgabe zugrunde, latente Beschleuniger für Epoxidharz-Systeme bereitzustellen, welche die genannten Nachteile des Standes der Technik nicht aufweisen, sondern eine hohe Reaktivität und sehr gute Lagerstabilität bei Raumtemperatur bzw. bei Temperaturen unterhalb der Härtungstemperaturen besitzen, und darüber hinaus möglichst halogenfrei bzw. toxikologisch unbedenklich sind.Of the It is an object of the present invention to provide latent accelerators for epoxy resin systems to provide the said disadvantages of the prior Not have technology but a high reactivity and very good storage stability at room temperature or at temperatures below the curing temperatures own, and above out as possible halogen-free or toxicologically harmless.
Diese Aufgabe wurde erfindungsgemäß dadurch gelöst, dass man als Beschleuniger unsymmetrisch substituierte Harnstoff-Derivate der allgemeinen Formel (I) 1 und R2 einen aliphatischen Kohlenwasserstoff-Rest mit 1 bis 4 C-Atomen bedeuten.This object is achieved according to the invention by using unsymmetrically substituted urea derivatives of the general formula (I) as accelerator. 1 and R 2 is an aliphatic hydrocarbon radical having 1 to 4 carbon atoms.
Es hat sich nämlich überraschenderweise gezeigt, dass die erfindungsgemäß vorgeschlagenen Beschleuniger nicht nur eine sehr gute Reaktivität und Lagerstabilität aufweisen, sondern auch keinerlei negativen Einfluss auf die mechanischen Eigenschaften des gehärteten Materials ausüben.It that is surprisingly shown that the invention proposed Accelerators not only have very good reactivity and storage stability, but also no negative impact on the mechanical properties of the hardened Exercise materials.
Contact us to discuss your requirements of China 6-Amino-1,3-dimethyluracil supplier. Our experienced sales team can help you identify the options that best suit your needs.
Der Einsatz von Dimethylharnstoff als Beschleuniger in Kombination mit Dicyandiamid wird zwar gemäß JP-OS 79-26000 für Urethan-modifizierte Epoxidharz-Systeme empfohlen, doch sind die Lagerstabilitäten in diesen Formulierungen nur vergleichbar mit denjenigen, die mit (1,1'-Methylendi- p-phenylen) bis (3,3-Dimethylharnstoff) (=MDI-Uron) erzielt werden. Überraschenderweise konnte mit den unsymmetrisch substituierten Harnstoff-Derivaten in den erfindungsgemäß beanspruchten Epoxidharz-Systemen wesentlich bessere Lagerstabilitäten erhalten werden, als dies mit MDI-Uron möglich ist.Of the Use of dimethylurea as accelerator in combination with Dicyandiamide is indeed according to JP-OS 79-26000 for Urethane-modified epoxy resin systems are recommended, but the storage stabilities in these formulations only comparable to those with (1,1'-methylenedipropylene) bis (3,3-dimethylurea) (= MDI-Uron). Surprisingly could with the asymmetrically substituted urea derivatives claimed in the invention Epoxy resin systems much better storage stability obtained with MDI-Uron.
Auch aus der JP-OS 81-133856, in der die Kombination von N,N-Dimethylharnstoff mit Phenolnovolaken als Härter für Epoxidharzsysteme im Bereich Halbleitersysteme beschrieben werden, findet sich kein Hinweis auf den Einfluss von N,N-Dimethylharnstoff auf die Lagerstabilität der entsprechenden Epoxidharz-Formulierungen.Also from JP-OS 81-133856, in which the combination of N, N-dimethylurea with phenolic novolac as hardener for epoxy resin systems are described in the field of semiconductor systems, there is no Indication of the influence of N, N-dimethylurea on the storage stability of the corresponding Epoxy resin formulations.
Erfindungsgemäß werden als Beschleuniger in Kombination mit Dicyandiamid als latenten Härter unsymmetrisch substituierte Harnstoff-Derivate der allgemeinen Formel (I) 1 und R2 einen aliphatischen Kohlenwasserstoff-Rest mit 1 bis 4 C-Atomen bedeuten. Hierbei kommen Methyl-, Ethyl-, Propyl- und Butylreste in Frage, die linear oder ggf. auch verzweigt sein können. Als bevorzugtes Harnstoff-Derivat wird N,N-Dimethylharnstoff verwendet.According to the invention asymmetrically substituted urea derivatives of the general formula (I) are used as accelerators in combination with dicyandiamide as latent hardener. 1 and R 2 is an aliphatic hydrocarbon radical having 1 to 4 carbon atoms. Here are methyl, ethyl, propyl and butyl radicals in question, which may be linear or possibly also branched. As the preferred urea derivative, N, N-dimethylurea is used.
Es ist als erfindungswesentlich anzusehen, dass die erfindungsgemäß vorgeschlagene Kombination von unsymmetrisch substituierten Harnstoff-Derivaten und Dicyandiamid für folgende Epoxidharz-Systeme eingesetzt werden: Epoxidharze auf Basis von ggf. halogenierten Bisphenolen vom Typ A oder F sowie auf der Basis von Resorcinol oder Tetrakisphenylolethan.It is to be regarded as essential to the invention that proposed according to the invention Combination of unsymmetrically substituted urea derivatives and dicyandiamide for following Epoxy resin systems are used: epoxy resins based on optionally halogenated bisphenols of type A or F and on the basis of resorcinol or tetrakisphenylolethane.
Epoxidharze auf der Basis von Bisphenol A und F werden überwiegend im Bereich der Faserverbundwerkstoffe, der Klebstoffe sowie auch höhermolekular als Festharze in Pulverlacken eingesetzt.epoxy resins based on bisphenol A and F are mainly used in the field of fiber composites, the adhesives as well as higher molecular weight used as solid resins in powder coatings.
Im Bereich der Elektrolaminate wird vom gehärteten Epoxidharz besondere Flammfestigkeit und hohe Temperaturbeständigkeit erwartet. Hierzu werden überwiegend halogenierte Systeme von Bisphenol A eingesetzt, z. B. Tetrabrombisphenol A-Derivate oder trifluormethylsubstituierte Varianten davon.in the Range of electric laminates becomes special from the cured epoxy resin Flame resistance and high temperature resistance expected. This will be predominantly halogenated systems of bisphenol A used, for. B. tetrabromobisphenol A derivatives or trifluoromethyl-substituted variants thereof.
Besonders flammfeste Composites werden mit Epoxidharzen auf der Basis von Resorcinol und Tetrakisphenylolethan hergestellt.Especially Flame resistant composites are based on epoxy resins Resorcinol and tetrakisphenylolethane.
Die Mengenverhältnisse von Dicyandiamid und Harnstoff-Derivat zu dem entsprechenden Epoxidharz kann in weiten Grenzen variiert werden. Es hat sich jedoch als besonders vorteilhaft erwiesen, das Dicyandiamid in einer Menge von 1 bis 15 Gew.-% und das Harnstoff-Derivat in einer Menge von 0,5 bis 15 Gew.-% jeweils bezogen auf das Epoxidharz einzusetzen.The proportions of dicyandiamide and urea derivative to the corresponding epoxy resin be varied within wide limits. However, it has turned out to be special proved advantageous, the dicyandiamide in an amount of 1 to 15% by weight and the urea derivative in an amount of 0.5 to 15 % By weight, based in each case on the epoxy resin.
Gemäß einer bevorzugten Ausführungsform kommen das Harnstoff-Derivat und das Dicyandiamid in einer möglichst feinteiligen Form zum Einsatz, wobei die Komponenten eine bevorzugte mittlere Teilchengröße von 0,5 bis 100 μm aufweisen. Die Härtungsreaktion der erfindungsgemäß vorgeschlagenen Beschleuniger und Härter mit dem jeweiligen Epoxidharzen kann nach den üblichen Methoden durchgeführt werden, wobei die Härtung bei Temperaturen zwischen 70 und 220 °C, insbesondere zwischen 80 und 160 °C durchgeführt wird.According to a preferred embodiment, the urea derivative and the dicyandiamide are used in as finely divided a form as possible, wherein the components have a preferred average particle size of 0.5 to 100 microns. The curing reaction of the inventively proposed accelerators and hardeners with the respective epoxy resins can be carried out by the usual methods, wherein the curing at temperatures between 70 and 220 ° C, in particular carried out between 80 and 160 ° C. becomes.
Die erfindungsgemäß beanspruchte Kombination von Harnstoff-Derivat als Beschleuniger und Dicyandiamid als latenter Härter eignet sich hervorragend für die Epoxidharz-Heißhärtung im Bereich der Faserverbundwerkstoffe (Composite-Materialien), Pulverlack-Beschichtungen, Elektrolaminate sowie Klebstoffe.The claimed according to the invention Combination of urea derivative as accelerator and dicyandiamide as a latent hardener is great for the epoxy resin hot curing in Range of fiber composites (composite materials), powder coating, electrical laminates as well as adhesives.
Die Vorteile der erfindungsgemäßen Beschleuniger/Härter-Kombination sind die ausgezeichnete Reaktivität und sehr gute Lagerstabilität. Überraschenderweise sind auch die mechanischen Eigenschaften der entsprechend ausgehärteten Harze ebenfalls hervorragend und vergleichbar mit denen der bereits eingesetzten blockierten Beschleuniger UR 200 (Diuron) und UR 300 (Fenuron).The Advantages of the accelerator / hardener combination according to the invention are the excellent reactivity and very good storage stability. Surprisingly are also the mechanical properties of the corresponding cured resins also excellent and comparable to those already used blocked accelerator UR 200 (Diuron) and UR 300 (Fenuron).
Aufgrund dieser sehr guten anwendungstechnischen Eigenschaften und einer geringen Toxizität sind die erfindungsgemäß vorgeschlagenen Härter/Beschleuniger-Systeme hervorragend für den technischen Einsatz geeignet.by virtue of This very good performance characteristics and a low toxicity are the proposed inventions Hardener / accelerator systems excellent for suitable for technical use.
Die nachfolgenden Beispiele sollen die Erfindung näher erläutern.The The following examples are intended to explain the invention in more detail.
BeispieleExamples
Folgende Produkte und Stoffe wurden in den Beispielen eingesetzt:The following Products and fabrics were used in the examples:
Epoxidharze:epoxy resins:
Epikote 828 (Fa. Resolution): Bisphenol-A-Harz, EEW 185 DER 664 UE (Fa. Dow): Festharz, EEW 910 (Harz)Epikote 828 (from Resolution): bisphenol A resin, EEW 185 DER 664 UE (Fa. Dow): solid resin, EEW 910 (resin)
Härter:Harder:
Dyhard 100 S (Fa. Degussa): mikronisiertes Dicyandiamid, Korngröße 98 % < 10 μm, 50% ca. 2,5 μm (Dyh 100 S)Dyhard 100 S (Degussa): micronised dicyandiamide, particle size 98% <10 μm, 50% approx. 2.5 μm (Dyh 100 s)
Beschleuniger:Accelerator:
Dyhard UR 200 (Fa. Degussa): mikronisiertes Diuron bzw. 3-((3,4-Dichlorphenyl)-1,1-dimethylharnstoff, Korngröße 98 % < 10 μm, 50 % ca. 2,5 μm (UR 200)
Dyhard UR 200 (Degussa): micronized diuron or 3 - ((3,4-dichlorophenyl) -1,1-dimethylurea, particle size 98% <10 μm, 50% approx. 2.5 μm (UR 200)
Dyhard UR 300 (Fa. Degussa): mikronisiertes Fenuron bzw. 3-Phenyl-1,1-dimethylharnstoff, Korngröße 98 % < 10 μm, 50 % ca. 2,5 μm (UR 300)
Dyhard UR 300 (Degussa): micronized fenuron or 3-phenyl-1,1-dimethylurea, Grain size 98% <10 μm, 50% approx. 2.5 μm (UR 300)
Dyhard UR 500 (Fa. Degussa): mikronisiertes TDI-Uron bzw. Toluyl-bis-1,1-dimethylharnstoff, Korngröße 98 % < 10 μm, 50 % ca. 2,5 μm (UR 500)
Dyhard UR 500 (Degussa): micronized TDI-uron or toluyl-bis-1,1-dimethylurea, Grain size 98% <10 μm, 50% approx. 2.5 μm (UR 500)
Dyhard MIA 5 (Fa. Degussa): mikronisiertes Addukt von Methylimidazol an Bisphenol-A-Harz (Epikote 828), Korngröße 98 % < 70 μm
Dyhard MIA 5 (Degussa): micronized adduct of methylimidazole on bisphenol A resin (Epikote 828), particle size 98% <70 μm
N,N-Dimethylharnstoff bzw. 1,1-Dimethylharnstoff (Fa. Merck): im Labor vermahlen, Korngröße 98 % < 10 μm, 50 % ca. 2,5 μm (1,1-DMH)
N, N-dimethylurea or 1,1-dimethylurea (Merck): Grinded in the laboratory, particle size 98% <10 μm, 50% approx. 2.5 μm (1,1-DMH)
N,N-Diethylharnstoff bzw. 1,1-Diethylharnstoff (Fa. Merck): im Labor vermahlen, Korngröße 98 % < 10 μm, 50 % ca. 2,5 μm (1,1-DEH)
N, N-diethylurea or 1,1-diethylurea (from Merck): Grinded in the laboratory, particle size 98% <10 μm, 50% approx. 2.5 μm (1,1-DEH)
MDI-Uron, (1,1'-Methylendi-p-phenylen) bis (3,3-Dimethylharnstoff) wurde nach bekannten Methoden aus MDI (1,1'-Methylendi-p- phenylen)diisocyanat und Dimethylamin hergestellt (z. B. EP 402 020 A1 , CS 233 068 B1 ) und anschließend im Labor vermahlen, Korngröße 98 % < 10 μm, 50 % ca. 2,5 μm
MDI-Uron, (1,1'-methylenedi-p-phenylene) bis (3,3-dimethylurea) was prepared by known methods from MDI (1,1'-methylenedi-p-phenylene) diisocyanate and dimethylamine (e.g. , EP 402 020 A1 . CS 233 068 B1 ) and then ground in the laboratory, particle size 98% <10 microns, 50% about 2.5 micronsAdditive:additives:
Lanco Wax TPS-040 (Fa. Lubrizol), mikronisiert im Labor 98 % < 80 μmLanco Wax TPS-040 (Lubrizol), micronized in the laboratory 98% <80 microns
Beispiel 1 (erfindungsgemäß):Example 1 (according to the invention):
Es wurden jeweils 5 g einer der Zusammensetzung in der linken Spalte von Tabelle 1 entsprechenden Formulierung aus Bisphenol A Harz (Epikote 828, EEW 185), Dyhard 100 S als Härter und erfindungsgemäßem Beschleuniger 1,1-Dimethylharnstoff (1,1-DMH) bzw. 1,1-Diethylharnstoff (1,1-DEH) sowie als Vergleich dazu die nicht erfindungsgemäßen Uron-Standardbeschleuniger Dyhard UR 200 (Diuron) und UR 300 (Fenuron) hergestellt. Es wurde jeweils die Gelzeit bei der angegebenen Temperatur bestimmt und die Reaktivität mittels DSC bestimmt.In each case, 5 g of a composition corresponding to the composition in the left-hand column of Table 1 from bisphenol A resin (Epikote 828, EEW 185), Dyhard 100 S as a hardener and inventive accelerator 1,1-dimethylurea (1,1-DMH) or 1,1-diethylurea (1,1-DEH) and, as a comparison thereto, the non-inventive Uron standard accelerators Dyhard UR 200 (Diuron) and UR 300 (Fenuron). In each case, the gel time was determined at the indicated temperature and the reactivity determined by DSC.
Als Temperaturprogramm für die Bestimmung der Peaktemperatur (DSC peak) wurde mit einer Rate 10 °C/min von 30 auf 350 °C aufgeheizt. Der Onset der Reaktion (DSC onset) wurde aus der gleichen Messung durch Anlegen der Tangente an den Reaktionspeak bestimmt.As Temperature program for the peak temperature (DSC peak) was determined at a rate of 10 ° C / min 30 to 350 ° C heated. The onset of the reaction (DSC onset) was from the same Measurement determined by applying the tangent to the reaction peak.
Für die Bestimmung der Glasübergangstemperatur (Tg) wurde das Material der Gelzeitbestimmung bei 120 °C herangezogen. Die Formulierung wurde durch Erhitzen auf 200 °C (Temperaturprogramm: 30 bis 200 °C, Heizrate 20 °C/min) und Halten dieser Temperatur für 30 Minuten vollständig ausgehärtet. Nach dem Abkühlen auf RT wurde die Probe mit einer Aufheizrate von 10 °C/min von 30 auf 200 °C aufgeheizt und daraus die Tg bestimmt.For the determination the glass transition temperature (Tg) the material was used for the gel time determination at 120 ° C. The formulation was heated to 200 ° C (temperature program: 30 to 200 ° C, heating rate 20 ° C / min) and holding this temperature for 30 minutes complete hardened. After cooling at RT, the sample was heated at a rate of 10 ° C / min 30 to 200 ° C heated and determined from the Tg.
Tabelle 1:
Tabelle 2: Beispiele (nicht erfindungsgemäß):
Im Vergleich der beiden Tabellen wird ersichtlich, dass die Reaktivität des 1,1-Dimethylharnstoffes als Beschleuniger durchaus vergleichbar zu den Standardbeschleunigern der Uron-Reihe ist. Dies gilt auch in etwas geringerem Maß für den 1,1-Diethylharnstoff. Auch die Glasübergangstemperatur des mit Dialkylharnstoff-Beschleunigern gehärteten Materials liegt im Bereich der Werte, die mit den Standardbeschleunigern Dyhard UR 200 und UR 300 erreichbar sind. Insbesondere bei Zusatz höherer Mengen Beschleuniger ist die Tendenz zur Tg-Erniedrigung bei den erfindungsgemäßen Stoffen weniger stark ausgeprägt.in the Comparison of the two tables will reveal that the reactivity of the 1,1-dimethylurea as an accelerator quite comparable to the standard accelerators the Uron series is. This also applies to a lesser extent for the 1,1-diethylurea. Also the glass transition temperature of the dialkyl urea accelerated material is within the range the values with the standard accelerators Dyhard UR 200 and UR 300 are reachable. Especially with the addition of higher amounts Accelerator is the tendency to Tg-lowering in the substances of the invention less pronounced.
Beispiel 2Example 2
Latenzversuche:Latency tests:
Einer Formulierung aus 100 Gew.-Teile Bisphenol-A-Epoxidharz (Epikote 828, EEW 185) und 6,5 Gew.-Teile Dyhard 100 S wurde jeweils die angegebene Menge latenter Beschleuniger zugegeben. Nach der angegebenen Lagerdauer bei der jeweiligen Temperatur wurde jeweils die Viskosität mittels Haake-Viskosimeter bestimmt.one Formulation of 100 parts by weight of bisphenol A epoxy resin (Epikote 828, EEW 185) and 6.5 parts by weight Dyhard 100 S was the respectively specified amount of latent accelerator added. After the specified Storage time at the respective temperature in each case the viscosity was Haake viscometer determined.
Tabelle 3:
Wie aus Tabelle 3 klar ersichtlich, weisen die erfindungsgemäßen Formulierungen erheblich bessere Eigenschaften bezüglich der Latenz auf: während in Formulierungen mit MDI-Uron bei 40 °C bereits nach 15 Tagen eine Verdopplung der Viskosität auftritt, ist dies beim 1,1-Dimethylharnstoff erst nach ca. 40 Tagen der Fall. Für MDI-Uron liegt die Verarbeitbarkeit der Formulierung unter 25 Tagen, während sie für Formulierungen mit 1,1-Dimethylharnstoff mehr als doppelt so hoch liegt (über 50 Tage).How from Table 3 clearly show the formulations of the invention significantly better latency characteristics: during in Formulations with MDI-Uron at 40 ° C already after 15 days one Doubling the viscosity This occurs with the 1,1-dimethylurea only after about 40 days the case. For MDI-Uron the processability of the formulation is less than 25 days, while she for Formulations with 1,1-dimethylurea more than twice as high lies (over 50 days).
Tabelle 4:
Die Verarbeitbarkeit der 1,1-Dimethylharnstoff enthaltenden Formulierungen ist bei Raumtemperatur ebenfalls erheblich höher als in Formulierungen mit MDI-Uron.The Processability of the 1,1-dimethylurea-containing formulations is also significantly higher at room temperature than in formulations with MDI Uron.
Beispiel 3Example 3
Vergleich N,N-Dimethylharnstoff mit verschiedenen Standardbeschleunigern:Comparison of N, N-dimethylurea with different standard accelerators:
Die Formulierungen bestehen jeweils aus 100 Gew.-Teile Bisphenol-A-Epoxidharz (Epikote 828, EEW 185), 6,5 Gew.-Teile Dyhard 100 S und der angegebenen Menge des jeweiligen Beschleunigers.The Each formulation consists of 100 parts by weight of bisphenol A epoxy resin (Epikote 828, EEW 185), 6.5 parts by weight of Dyhard 100 S and the stated amount of the respective accelerator.
Tabelle 5:
Im Vergleich mit Standardbeschleunigern der Uronreihe wird der Vorteil der Verwendung von 1,1-Dimethylharnstoff in Einkomponentengemischen noch deutlicher: während die Standardprodukte UR 300 und UR 500 bei 40 °C nur bis zu 1 Woche verarbeitbar sind, kann eine Formulierung mit MDI-Uron immerhin 3 Wochen verarbeitet werden. Die Dimethylharnstoff enthaltende Formulierung ist sogar 7 bis 8 Wochen verarbeitbar.in the The advantage compared to standard Uron series accelerators the use of 1,1-dimethylurea in one-component mixtures even clearer: while the standard products UR 300 and UR 500 can only be processed for up to 1 week at 40 ° C After all, a formulation containing MDI-Uron can be processed for at least 3 weeks become. The dimethylurea-containing formulation is even 7 to 8 weeks workable.
Beispiel 4Example 4
Beispiele Pulverlack:Examples of powder coating:
Folgende Formulierungen wurden miteinander verglichen:
Die Formulierungen wurden jeweils bei 95 °C extrudiert.The Each formulation was extruded at 95 ° C.
Tabelle 6:
Die mechanischen Eigenschaften der Urone in Pulverlackformulierungen sind absolut vergleichbar mit dem Methylimidazol-Addukt (Dyhard MIA 5) bei gleichzeitig geringerer Vergilbungsneigung und besseren Verlaufseigenschaften.The mechanical properties of the urons in powder coating formulations are absolutely comparable to the methylimidazole adduct (Dyhard MIA 5) with a lower yellowing tendency and better Leveling properties.
The company is the world’s best China Ticagrelor factory and suppliers supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.