MXPA06009092A - Overcoat lacquer - Google Patents

Abstract

The invention relates to an overcoat lacquer containing a) at least one binding agent containing alkyd resins made from tris-(2-hydroxylethyl)-isocyanurate, 2,6-naphthaline dicarboxylic acid, drying fatty acids, and, optionally, other components known from alkyd resin chemistry, b) at least one solvent or at least one technical solvent or mixture thereof based on hydrocarbon and c) at least one siccative or at least one mixture of siccatives or several anti-skinagents.

Description

VARNISH FOR COATING The present invention relates to an air-dried varnish particularly suitable for coating flat modules in electronics, hybrids, SMD modules, and printed circuit boards which is subject to a high thermal load. The varnish can also be used to impregnate electrical windings or as a protective varnish for electrical windings. A coating varnish for flat modules, hybrids, SMD modules and other components used in printed circuit boards is required to protect varnished components from moisture, chemicals, dust, etc. The additional intention is that the protective coating should increase the safety of electronic modules with respect to weather and tracking current. The capacity to withstand the thermal load must be correct for the field of use. Typical varnishes have a temperature index (T > I) of 130. The desire, particularly in the automotive industry, is that a coating varnish has an TI greater than 155. Effective adhesion is assumed to be a reality. to a variety of substrates. The processing is typically by selection, coating, selective immersion, spray or injection process. With a varnish of this type, a thickness of the film is 10 μm or more.

The cutting-edge technology is the use of air-dried or oven-dried varnishes. The binder is typically an alkyd resin, an acrylic resin or a polyurethane resin. It has been known for a long time about alkyd resins for surface protection and has also been described for a long time (W. Oburger, Die Isolierstoffe der Elektrotechni, Springer 1957. Tillar Shugg, Handbook of Electrical and Electronic Insulating Materials IEEE Press 1995) . Alkyd resins can be formulated as such or as modified resins (imide, urethane), without or with additional curing agents (melamine resins, phenolic resins, (blocked) isocyanates) in organic solvents. These varnishes are of low viscosity and in addition to the binders comprise catalysts and additives. It is known that alkyd resins are not particularly stable at temperature, but have the advantage that, given the correct composition of binders, they can be dried by air, and thus allow an effective process in cost. Where tris (2-hydroxyethyl) isocyanurate is incorporated into branched polyester resins or modified polyester resins, products are obtained which have a relatively high thermal rating (K-.Lienert, Poly (ester-imide) s for industrial use, p 48, in Progress in Polyimide Chemistry, vol. 1441, 1999). Moreover, EP 0 813 580 describes how using the naphthalenedicarboxylic acid structures in place of the typical structures of terephthalate in modified polyesters and polyesters likewise leads to an improvement in the thermal properties. The problem is solved by the present invention by providing a varnish for air-dried and low viscosity coating for coating flat modules, hybrids, SMD modules, etc., which can be processed with typical lines and having an IT or IEC 60216 of at least less 155. This problem is solved by a coating varnish comprising: a) at least one binder comprising alkyd resins synthesized from tris (2-hydroxyethyl) isocyanurate, 2,6-naphthalene dicarboxylic acid, drying fatty acids, and, if desired, additional known components of the alkyd resin chemistry, b) at least one solvent of at least one technical solvent mixture thereof comprising at least one solvent containing hydrocarbons, and c) at least a secant or at least a mixture of siccatives and one or more anti-scaling agents. According to the invention, the alkyd resin is dissolved in the solvents together with the siccatives and others auxiliary This produces a varnish that, depending on the concentration of agglutinator and solvent composition, has different viscosities. Typically, varnishes for coating flat modules in electronics, hybrids and SMD modules have viscosities of between 100 mPas and 400 mPas, depending on the application, the processing technology and the thickness of the desired layer. According to the component of the invention a) it comprises at least one binder which is prepared through the reaction of tris (2-hydroxyethyl) isocyanurate, 2,6-naphthalene dicarboxylic acid, drying fatty acids and other known components of the alkyd chemistry.

Preferably component a) consists of a binder. Preferably the binder contains 33.0% - 50.0% of tris (2-hydroxyethyl) 9-isocyanurate, preferably 37.0% - 45.0%, more preferably 38.0% - 43.0% 14.0% - 20.0% of dimethyl-2,6-naphthalene-dicarboxylate, preferably 15.0% - 19.0%, more preferably 16.0% - 18.0% 34.0% - 47.0% talloyl fatty acid, preferably 38.0% - 44.0%, more preferably 40.0% - 42.0%. This resin can, according to the invention contain 1.0% - 15.0% of a modifier, an example is a mixture of toluene 2,6- and 2,4-diisocyanate. The preparation of alkyd resins is common knowledge and can be found in several standard works of the chemical literature. It involves the heating of the components, with or without an esterification catalytic, typically at temperatures between 190 and 240 ° C. The reaction is typically carried out under an inert gas. In order to facilitate the expulsion of the formed water it is possible to use an azeotropic mixture, an additional agent, and / or vacuum. The monitoring of the condensation course is typically achieved by determining the acid number and / or the condensation viscosity. The constituents of an alkyd resin are polyols, polycarboxylic acids, and fatty acids. Polyols that may be used include, in addition to the tris (2-hydroxyethyl) isocyanurate of the invention, ethylene glycol, propylene glycol, glycerol, trimethylolpropane, etc. Preference is given, according to the invention, to the use of tris (2-hydroxyethyl) isocyanurate. The polycarboxylic acids which can be used, in addition to the 2,6-naphthalene dicarboxylic acid of the invention, are phthalic acid, isophthalic acid, terephthalic acid, etc. Typically the corresponding dimethyl esters or the acid anhydrides are used with the In order to accelerate the synthesis of the agglutinator. Preference is given to using 2,6-naphthalenedicarboxylic acid or dimethyl 2,6-naphthalenedicarboxylate. As a fatty acid, from an air drying system, a drying fatty acid or a mixture of fatty acids is used, such as linolic acid, linolenic acid, oleic acid, talloyl fatty acid, etc. Instead of a polyol and a fatty acid it is also possible when the binders of the invention are prepared, the drying acids boiled, the examples are flax seed oil, bean bean oil with degree of coating, etc. The alkyd resins synthesized from the described components can, according to the invention, be modified. For the alkylic modifier resins it is possible to use a variety of components that react with the hydroxyl groups and / or the acid groups of the resins. Reacting with the hydroxyl groups are mono- or polyisocyanates, which may be aromatic, aliphatic or cycloaliphatic such as phenyl isocyanate, naphthyl isocyanate, toluene 2,6- and 2,4-diisocyanate or a mixture of both, 4, 4 ' diisocyanatodiphenylmethane, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, etc. Other components that react with the hydroxyl groups are, for example, resins or melamine resins.

A large number of these compounds are available industrially. The acid group of the alkyd resins can easily react with epoxy resins. Examples of epoxy resins include diglycidyl ether of bisphenol A and diglycidyl ether of bisphenol F, limonene oxide, e, 4-epoxycyclohexylmethyl 3 ', 4-epoxycyclohexanecarboxylate, and also monofunctional oxiranes such as glycidyl phenyl ether, for example, glycidyl ethers of long-chain alcohols or polyalkylene glycols. A further modification of the alkyd resins consists of boiling them with natural drying oils, with natural resins, with maleic anhydride, etc. Mention of these possibilities is by way of example and does not restrict the varnish binders of the invention. The binder of the invention can be prepared preferably from 33.0% - 50.0% tris (2-hydroxyethyl) isocyanurate, preferably 37.0% - 45.0%, more preferably 38.0% - 43.0% 14.0% - 20.0% of 2.6. dimethyl naphthalenedicarboxylate, preferably 15.0% - 19.0%, more preferably 16.0% - 18.0% 34. 0% - 47.0% talloyl fatty acid, preferably 38.0% - 44.0%, more preferably 40.0% - 42.0%. This resin can, according to the invention, be modified with 1.0% - 15.0% of a modifier, for example, a mixture of toluene 2,6- and 2,4-diisocyanate. The right solvents or solvent mixtures (component b) includes mixtures of aliphatic and / or aromatic hydrocarbons that are known in varnish chemistry, such as Shellsol D25 and D40, Solvesso 100 and Solvesso 150, toluene, xylene, and distillation cuts comprising them. These solvents are typically but not necessarily used in a mixture with esters, ketones, lactose and other typical varnish solvents. The following description is intended to illustrate the diversity of compounds that may be employed: esters for mention herein including ethyl, isopropyl and butyl acetate; ketones such as ethyl methyl ketone, methyl isopropyl ketone, isoamyl methyl ketone and isophorone which can be used in the same way. Gamma-butyrolactone is a representative of the class of lactose. Other typical varnish solvents are hydroxy esters such as methoxypropanol and -butanol, ether esters, such as methoxyprop-2-yl acetate and cyclic esters such as propylene carbonate and glycerol carbonate, for example. Reference can be made here to the technical literature related to varnish solvents. Component c) comprises metal salts, such as lead, cobalt and zirconium octoate, manganese, vanadium, and calcium naphthenate or combinations of these dryers, which catalyze the crosslinking of the alkyd resins through atmospheric oxygen. Anti-scaling agents included in component c), such as ethyl methyl ketoxime, tocopherol, Ascinin® Atiskin VP 242 (available from Borchers, Germany), prevent the formation of a film layer on the surface of the varnish during storage of the varnishes of the invention in the containers. Typically, and which also depends on the use of the varnish, the alkyd resin varnishes can, if desired, include co-catalysts, corrosion inhibitors, defoamers, flow control agents, and wetting agents. Reference can be made here to the relevant varnish manuals. To prepare the coating varnish of the invention it is preferred to dissolve the existing binder in component b), to carry out the modification if desired, to carry out the heating if desired and then add component c). The coating varnish of the invention can preferably be used to coat wires electrical, electric windings, as a coating on flat modules in electronics, hybrids, SMD modules, assembled printed circuit boards and to impregnate electrical windings. The invention is described in more detail below with reference to the examples. The tests are carried out in accordance with the DIN and IEC standards. EXAMPLES Example 1 1044 g of tris (2-hydroxyethyl) isocyanurate (THEIC), 460 g of dimethyl 2,6-naphthalenedicarboxylate (NDC), 1085 g of oil tall fatty acid, and a typical esterification catalyst are used to prepare an alkyd resin having an acid number of less than 5 mg KOH / g. The resin is dissolved in 700 g of methoxyprop-2-yl acetate and 1700 g of benzene with degree for coatings. The solution is mixed with 208 g of a technical mixture of toluene 2,6- and 2,4-diisocyanate and heated until the IR band of the NCO group is no longer visible. 10 g of lead octoate and 10 g of cobalt octoate and 44 g of ethyl methyl ketoxime are also added. Using about 354 g of methoxyprop-2-yl acetate and about 852 g of benzene with degree for coating, the varnish is adjusted to a ISO 6 flow time of 38 s. A printed circuit board is immersed in the varnish and then allowed to cure at 90 ° C for 1 hour. The formed film is smooth and free of traces. The quantities in cross section to GT 0 B (DIN 53151). The resistance broken down to DIN EN 60464-2 is found to be l * l16Ocm-1. IT, through mass loss of fiberglass to IEC 60216 is 166. The varnish is used to impregnate drill rods to IEC 61033 (method A), and after curing (1 hour at 110 ° C), it is measures the baking resistance. At 23 ° C it is 47 N. Example 2 522 g of (THEIC), 210 g of NDC, 498 g of oil tall fatty acid and 56 g of a technical mixture of toluene 2,6- and used 2, 4 -diisocyanate as described in Example 1 to prepare a resin and formulated analogously with the amounts of solvents, siccatives and descaling agent indicated. The varnish can be used to varnish and cure easily. The TI through mass loss in the fiberglass to IEC 60216 is 157. Comparative Example 3 The experiment of Example 1 is repeated except that the resin is not modified with the toluene mixture 2,6- and 2, 4 -diisocyanate. After varnishing and healing, Sticky films are obtained. Therefore, subsequent tests are unnecessary. Comparative Example 4 1044 g of (THEIC), 314 g of isophthalic acid, 185 g of talloyl fatty acid and 208 g of technical mixture of toluene 2,6- and 2,4-diisocyanate were used as described in Example 1 to prepare a resin and are formulated analogously with the indicated amounts of solvent, drying agent and descaling agent. The varnish is varnished and easily cured. TI through the loss of mass on glass fiber to IEC 60216 is only 140. Comparative Example 5 536 g of trimethylolpropane, 460 g of NDC, 1085 g of talloyl fatty acid and 208 g of a technical mixture of toluene 2,6- and 2,4-diisocyanate were used as described in Example 1 to prepare a resin and are formulated analogously with the amounts of solvent, drying agent and descaling agent indicated. The varnish is varnished and easily cured. TI through the loss of mass on the glass fiber to IEC 60216 is only 139. Comparative Example 6 536 g of trimethylolpropane, 314 g of isophthalic acid, 1985 g of talloyl fatty acid and 208 g of Technical mixture of toluene 2,6- and 2,4-diisocyanate were used as described in Example 1 to prepare a resin and are formulated analogously with the indicated amounts of solvent, drying agent and descaling agent. The varnish is varnished and easily cured. TI through the loss of mass on fiberglass to IEC 60216 is only 132.

Claims (19)

1. CLAIMS 1. A coating varnish comprises a) at least one binder comprising acrylic resins synthesized from tris (2-hydroxyethyl) -isocyanurate, 2,6-naphthalenedicarboxylic acid, drying fatty acids and, if desired, also known components of the alkyd resin chemistry, b) at least one solvent or at least one technical solvent or solvent mixture comprising at least one hydrocarbon-containing solvent mixture, And c) at least one siccative or at least one mixture of siccatives and one or more anti-scaling agents.
2. 2. The coating varnish of claim 1, characterized in that component a) further comprises ethylene glycol, propylene glycol, glycerol, trimethylolpropane or mixtures thereof.
3. 3. The coating varnish of any of the claims, characterized in that component a) further comprises phthalic acid, isophthalic acid, terephthalic acid or mixtures of these compounds.
4. 4. The coating varnish of any of the preceding claims, characterized in that at least part of the dicarboxylic acids are in the form of dimethyl esters.
5. 5. The coating varnish of any of the preceding Claims, characterized in that the component a) comprises as fatty acids, linolic acid, linolenic acid, oleic acid, talloyl fatty acid or mixtures of these compounds.
6. 6. The coating varnish of any of the preceding claims, characterized in that component a) comprises modified alkyd resins.
7. The coating varnish of any of the preceding claims, characterized in that the component a) contains 1. 33.0% - 50.0% by weight of tris (2-hydroxyethyl) isocyanurate, preferably 2. 14.0% - 20.0% by weight of dimethyl 2,6-naphthalenedicarboxylate, 3. 34.0% - 47.0% by weight of talloil fatty acid 4. 1.0% - 15.0% by weight of modifier (s), the percentages by weight in this case add up to 100.0% by weight.
8. The coating varnish of any of the preceding Claims, characterized in that the binder of component a) contains 37.0% - 45.0% by weight of tris (2-hydroxyethyl) isocyanurate, 15.0% to 19.0% by weight of 2, 6- dimethyl naphthalenedicarboxylate and 34.0% - 47. 0% by weight of talloil fatty acid, the percentages of weight added in this case are 100% by weight.
9. 9. The coating varnish of any of the preceding claims, characterized in that the binder present in component a) contains 38.0% - 43.0% by weight of tris (2-hydroxyethyl) isocyanurate 16.0% - 18.0% by weight of 2.6 dimethylnaphthalenedicarboxylate 40.0% - 42.0% by weight of talloyl fatty acid, the weight percentages in each case add up to 100.0% by weight.
10. 10. The coating varnish of any of the preceding claims, characterized in that component b) comprises mixtures of aliphatic or aromatic hydrocarbons or mixtures thereof.
11. 11. The coating varnish of any of the preceding claims, characterized in that component c) comprises an additional solvent of the class of esters, ketones, lactose or other typical solvent for varnish.
12. 12. The coating varnish of any of the preceding claims, characterized in that the component c) comprises lead, cobalt or octoate of zirconium, manganese, vanadium or calcium naphthenate or combinations of one or more of these drying agents.
13. The coating varnish of one of the preceding claims, characterized in that the component c) comprises, as anti-scaling agents, ethyl methyl ketoxime, tocopherol, Ascinin® Antiskin VP 242 or mixtures of these substances.
14. 14. The coating varnish of one of the preceding claims, characterized in that component c) further comprises co-catalysts, corrosion inhibitors, defoamers, flow control agents, and wetting agents.
15. 15. The process for preparing a coating varnish of one of Claims 1 to 14, characterized in that the binder present in component a) is dissolved in modified component b) if desired, heated, if desired, and then add component c.
16. 16. The process of the Claim <; sic > 16, characterized in that after the addition of component b) a modifier is added.
17. The process of Claim 16, characterized in that toluene diisocyanate is used for the modification.
18. 18. The process of Claim 17, characterized in that 1.0% - 15.0% by weight of a mixture of toluene 2,6- and 2,4-diisocyanate is used. The use of the coating varnish of any one of Claims 1 to 14 for coating electric wires and electrical windings and also as a coating on flat modules in electronics, hybrids, SMD modules, assembled printed circuit boards, for impregnating the electrical windings .