DD151466A1 - METHOD FOR PRODUCING STORAGE-STABLE POLYURETHANE-ONE COMPONENT LACQUERS - Google Patents

Abstract

The aim of the invention is to develop a process for the preparation of polyurethane one-component paints, which at the same time have a high storage stability, a low content of monomeric residual diisocyanates as well as excellent technical and mechanical properties of the coating systems, good pigmentability and drying speed. Inventive compositions are used for the process used as a reaction accelerator for the preparation of NCO-limited prepolymers special hydroxyl-functional metal catalysts. These are compounds of the general type I, II, III and IV: M & agrII! R * (I), R &sub1; -n! M & expIII! R * (II), R & ind4-n! M & expiv! R * (III), R & ind5 -N! M & expV! R * (IV) where R is any alkyl, cycloalkyl or aryl radical; R & exp1! stands for any hydroxyl-functional organic radical. Moisture-curing polyurethane one-component coatings, especially as clearcoats, have considerable significance for the production of coatings, coatings, sealings, etc., owing to their performance advantages.

Description

17921

Title of the invention

Process for the preparation of storage-stable polyurethane Einkompo nentenlacke

the invention;

Moisture-curing polyurethane one-component coatings, especially as clearcoats, have considerable significance for the production of coatings, coatings, sealants, etc., owing to their performance advantages.

Characteristic of the known technical solutions

The known technical solutions are based on, in particular, reacting diisocyanates having different reactivity of the KCO groups with low molecular weight hydroxy compounds to form ITCO-bound prepolymers. Essential aspects in the preparation are the complete exclusion of atmospheric moisture, dehydration of the solvents and reactants, because in turn no storage-stable products are obtained. By using water binding agents, e.g. B-. Molecular sieves, orthoesters, tosyls, isocyanates, etc., one is able to overcome these difficulties. Naturally, the structure of the UCO-bound oligomers prepared has a decisive influence on the storage stability and other properties Preparation of prepolymers for polyurethane one-component coatings A special reaction procedure is necessary in order to obtain products with a favorable structure and low contents of monomeric toxic residual isocyanates.

Low reactivation temperatures are preferred since the differences in the reactivity of the diisocyanate ICO groups are greatest. Especially in the case of cycloaliphatic diisocyanates, these conditions have gained little practical importance because of the long reaction times. "Economically acceptable Solutions operate at a temperature range of 60 to 150 ⁰ G, where the reactivity of any diisocyanates is sufficiently high * In a number of known methods, a reaction time reduction by catalysts is proposed, which are often needed to accelerate acceleration anyway. "Here are sometimes and especially at high temperatures extensive In addition, it is known that, in particular, free, unbound catalysts which contain metals in a higher valence state are particularly suitable for crosslinking reactions which in turn adversely affect the storage stability.

ITI IV

th, Z ₆ B "Pe, Sn, etc., reduce the oxidation and weather resistance of polyurethane coatings and lead to premature degradation of the binder" It has therefore been proposed to use Polyesteralkohle for the production of polyurethane Einkoinponentenlacken, the tin compounds catalytic incorporated in the molecule · the production of polyurethane one-component using such tin-containing polyester alcohols can be carried out at room temperature and maintaining relatively fast drying, good storage-stable one-component and possibly pigmentable _e Man however is the use of special polyester alcohols bound '

goal of

The aim of the invention is to develop a process for the preparation of polyurethane one-component paints, which at the same time ensure a high storage stability, a low content of monomeric residual diisocyanates and excellent high-tech and mechanical properties of the coating systems, wherein the coatings also good pigmentation and a sufficient Should have Trocknungsgeschvdndigkeit ₀

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Explanation of the essence of the invention

The object of the invention is to develop a process for producing storage-stable polyurethane one-component coatings using a highly active catalyst which makes it possible to prepare polyurethane one-component coatings at temperatures of from 10 to 60 ° C. using any polyhydroxy compounds.

In accordance with the invention, the object is achieved by using special hydroxyl-functional metal catalysts as reaction accelerators for the preparation of HOO-limited polyurethane prepolymers.

According to the invention, these are compounds of the general type I, II, III and IV:

n1,% TTT 1 , χ TV 1

^ 5-η ^ n (1 ^) »where

R is any alkyl, cycloalkyl or aryl radical; R is any hydroxyl-functional organic radical. Particular preference is given to reaction products of dialkyltin oxides, in particular dibutyltin oxide with hydroxycarboxylic acids, lactones, cyclic carbonates, half-esters of dicarboxylic acids with polyhydroxyI compounds or half-amides with corresponding aminoalcohols corresponding to general formula III. Analogous reaction products can be used with oxides, hydroxides, carbonates, etc. of the other general structures I, II and IV mentioned.

The preparation of the catalysts of the invention can be carried out in a simple manner by known methods. Thus, for example, dibutyltin bis (2-hydroxyethyl maleate) from maleic anhydride, glycol and dibutyltin oxide is available in quantitative yield. The highly viscous products are advantageously not isolated but are dissolved in a lacquer solvent and then added to the aqueous solution. limited prepolymers using the catalysts of the invention is carried out in the rule

SO ₅ that the submitted organic di- or polyisocyanates in the manner of solvents with polyhydroxyI be¬ be treated. It is essential to the invention that the reaction "in! Temperature range of 10 to 60 ⁰ C proceeds at a sufficiently high Geeehwindigkeit" Preferably, temperatures of 25 to 50 ⁰ C are used. Under- polyhydroxy! Compounds refers to the conventionally used in polyurethane chemistry linear or branched polyether - and polyester alcohols of molecular weights from 400 to 5000, Abmisehungert same or * blends with low molecular weight hydroxy _see, for example, compounds glycols butanediol, hexanediol, Äthylhexandiol, Heopentylglykol, hexanetriol, glycerol, trimethylolpropane, etc, "preferred diisocyanates are toluene diisocyanate and, in particular, which as IPDI known to call 3-Isocyanatomethyl ~ 3 »5j5" trimethylcyclohexylisocyanat © Instead of the simple diisocyanates suitable polyvalent polyisocyanates may be used, in particular in combination with predominantly linear polyhydroxyl compounds. Suitable polyisocyanates are reaction products which are accessible from diisocyanates and polyhydric alcohols, such as diglycol, butanediol, trimethylolpropane, etc., wherein one mole of OH groups is reacted per mole of biisocyanate. In analogous manner, as polyisocyanates, products of diisocyanates and biuretizing agents, eg. For example, water, tert-butanol, etc., which are referred to as biuret polyisocyanates, di- and trimerized diisocyanates, or "modified by other methods used diisocyanates." Particularly important in the context of the invention are the adducts prepared in the presence of catalysts of the invention Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI) and trimethylolpropane or mixtures thereof with butanediol (1,3) or diglycol, which can be converted into the ready-to-use lacquer solutions with linear polyhydroxyl compounds immediately after preparation without changing the reaction vessel. Taking into account the functionality of the isocyanate component, the choice of the polyhydroxyl compound used is such that the resulting 5TC0-bound prepolymers have LiCO functionalities of 2 to ₉ preferably about 3 _e

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The stoichiometric ratios are chosen so that the equivalent ratio UCO / OH is between 1.5 and 2.1, which is favorable in the reaction of diisocyanates with trifunctional polyester or polyether alcohols in the value of 1.8 to 2 _e 1, whereas the conversion of polyisocyanates is higher Ensures functionality with linear PolyhydroxyIverbindungen at a total NCO / OH ratio of 1.5 to 1.8 good properties. It is essential to the invention that due to the low temperatures and by the presence of the catalysts of the invention, the adduct formation is relatively uniform, other undesirable crosslinking reactions, for example, by isocyanurate, allophanate, biuret, carbodiimide and other reactions, avoid, and a relatively low content monomeric residual diisocyanates is achieved. This is particularly important in view of the physiological safety of the one-component paints prepared therefrom, and on the other hand requires the desired high storage stability. As solvents for carrying out the prepolymerization, all anhydrous solvents are suitable, provided that they contain no reactive hydrogen atoms. "The usual products for polyurethane coatings are suitable, such as ethyl acetate, butyl acetate, ethyl glycol acetate, methyl ethyl ketone and alkylated as cheap cosolvents aromatics, such as toluene and xylene. It is common to use solvent mixtures. Due to the reaction conditions at low temperatures and the presence of the catalysts of the invention can be relatively high when using IPDI due to the uniformity of the products formed''vonromate in the solvent mixture without a diminishing storage stability must be feared, The catalysts of the invention can both Isocyanate component as well as the polyhydroxyl component or both in total or in portions during the course of the reaction. The catalyst concentration can be between 0.01 to 2 % and depends on the structure of the catalyst according to the invention and the selected isocyanate component. In the case of dibutyltin-1-bis (2-hydroxyethyl maleate), 0.04 % (as dibutylamine oxide;

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Total solids) for a sufficient reaction acceleration of IPDI "reactions from" The particular importance of the products produced is the possibility of pigmentation, which can be done for example by incorporation of commercially available pigments after the preparation of the prepolymers, but is preferably carried out so that the diluted with solvents PolyhydroxyIverbindung or a part thereof before the reaction with the isocyanate component in the presence of 0 * 5 to 2 % of ortho esters of .formic acid and / or silica or other water-binding agents in conventional dispersing pigmented and the pigment dispersion is reacted. The presence of the catalysts according to the invention, in conjunction with the low reaction temperatures, which converts all the water present in the pigments, solvents and hydroxyl components to urea groups during the reaction in the sense of a bifunctional reactant, does not lead to a viscosity-increasing crosslinking. The adducts are preferably made with 50 to 70 % pesticide, and then diluted depending on the application intent. The drying takes place relatively quickly, but can still be accelerated by the addition of tertiary amines (0.1 to 0.2 %) or organometallic compounds (0.01 to 0.2 %) . Depending on the type of products used elastic or hard paint films can be obtained, which have excellent mechanical properties. The polyurethane one-component lacquers according to the invention can be processed in any desired manner and are suitable for all known fields of use of polyurethane lacquers, in particular pigmented one-component lacquers based on IPDI are suitable as light-stable alternative of the known two-component polyurethane systems based on hexamethylene diisocyanate derivatives with biuret structure »

embodiments

Example 1a (comparative example)

To a solution of 222 parts of 3-IsocyanatometbyI-3> 5,5-trimethylcyclohexyl isocyanate (IPDI), 245 parts of xylene is allowed

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while stirring at a temperature of 100 ⁰ C, a solution of a polyester alcohol of adipic acid, trimethylolpropane and neopentyl glycol (OH number: 204) is added dropwise 270 parts of ethyl acetate in 245 parts of ethyl glycolate, then stirred for a further 2 h and allowed to stand for 24 h. The following analytical data of the 50% prepolymer is obtained: UCO: 4.15% _f IPDI: 3.0% a (20 ⁰ C): 80 cP _o

Example 1b (comparative example)

The procedure is as in Example 1a, but the reaction is carried out at 30 to 35 ⁰ C and works in the presence of 1.5 parts of dibutyltin dilaurate (50% in ethyl glycol acetate) _e The following analytical data are obtained:

ICO: 3.51 % ₉ IPDIi 1.8%

rj (20 ⁰ C) = 140 cP, 230 cP (6 months), 640 cP (12 months), 1080 cP (18 months)

Example 2 (solution according to the invention)

To a solution of 222 parts of IPDI, 245 parts of xylene and 0.5 part of dibutyltin bis (2-hydroxyethylmaleinate) (I, 50% in ethyl glycol acetate) is left under stirring at 30 ⁰ C a Löbung a polyester alcohol of adipic acid , Trimethylolpropan and Ieopentylglykol (OH number: 204), consisting of 270 parts of polyester alcohol, 245 parts of ethyl glycol acetate, 1.0 parts I, eo drops so that the temperature does not exceed 35 ° C, After the addition is stirred for one more hour and after 24 h following analytical data:

HCO: '3.67%, IPDI: 1.5 %

\\ (20 ⁰ C) = 130 cP, 1-50 cP (6 months), 190 cP (12 months), 310 cP (18 months) · "

Example 3

The procedure is as in Example 2, but replacing the polyhydroxy1 compound by a polyester alcohol of adipic acid, phthalic anhydride, Kexantriol and Butandiol- (1,3) (OH number β 213, M »1060), which has a functionality of 4 · Man receives a product with the following data: KCO = 3.66 % _t IPDI = 1.21 SS, ^ (20 ⁰ C) - 180 cP _? Storage stability; 12 months, pendulum hardness according to TC-L 107 / 06106.01 = 178 s (8 days), 247 s (3 h at 120 ° 0) _e

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Example 4

The procedure is as in Example 2, but replacing the Polyhydroxy1 compound by a mixture of 31.2 parts of trimethylolpropane, 16j8 parts of diglycol and 187 parts of a polyester alcohol of adipic acid, diglycol and trimethylolpropane (OH number = 60, M = 2400) dissolved in 212 parts of ethyl glycol acetate, and the catalyst by an equal amount of dibutyltin bis (2-hydroxyethoxyethyl phthalate) (5Cf5ig in ethyl glycol acetate, II). There are the following data received? IICO: 3.32%, IPDI: 0.92%, η (20 ⁰ C): 360 cps, storage stability: greater than 12 months, pendulum hardness TGL 107 / 061.01 = 42 s (1 day), 155 s (7 days) *

Example 5

The procedure is as in Example 2, but leads to the following Polyhydroxy Iv compounds in the following order: 44.6 parts Trimethylolprcpan and 1 part II in 40 parts of ethyl glycol acetate at ca _e 50 ⁰ C and then 170 parts of a polyester alcohol from adipic acid, hexanediol ( 1.6) and Heopentylglykol (OH number = 65, M = 1700) in 150 parts of ethyl glycol acetate. The 50% prepolymer solution has the following data: HCO: 3.18%, IPDI: 0.67%, η (20 ⁰ C) == 205 cP, storage stability: greater than 12 months, pendulum hardness TGL 107 / 061.01 = 54 s ( 1 day), 187 s (7 days), 204 s (3 h at 120 ^° C.).

Example 6

The procedure is as in Example 5, but instead of the polyester alcohol 125 parts of a polypropylene glycol (M = 1000, OH number: 112) for the implementation, the solvent use is reduced so that a 50% solution in ethyl glycol acetate / xylene is obtained comprising: NCO 3.17%, IPDI: 0.95%, '] (20 ⁰ C) = 275 cP, storage stability: greater than 18 months, pendulum hardness TGL 107 / 061,01 33 s (1 day), 124 s (7 days).

μ 9 · *

Example 7

With stirring, mixing the solution of an IPDI-trimethylolpropane · propanadduktes (60% in ethyl glycol acetate / xylene, NCO: 9.0%, '9 (20 ⁰ C) = 720 cps) with 1 part of II and 165 parts of a hydroxyl-containing oligourethane from Adipic acid, neopentyl glycol and hexamethylene diisocyanate (OH number: 132, M = 1300), dissolved in 254 parts of ethyl glycol acetate / xylene and gives after 24 h standing, the following analytical data: HCO: 3.02%, IPDI: 0.46 %, η ( 20 ⁰ C) = 630 cP, storage stability: greater than 12 months, pendulum hardness TGL 107 / 061.01 = 44 s (1 day), 153 s (7 days), 238 s (3 hours at 120 ⁰ C).

Example 8

A solution of 222 parts of IPDI and 0.5 parts of I, a trituration consisting of 270 parts of the polyester alcohol from Example 2, 310 parts of rutile, 195 parts of ethyl glycol acetate, 195 parts of xylene, 5 parts of ethyl orthoformate, 1 part of silicone oil (10% in xylene) and 1 part I with such a speed added with stirring that the temperature does not rise above 35 ⁰ C. After standing for 24 h, a pigmented prepolymer with excellent storage stability is obtained. Data: IICO = 2.6% _IPDI% = 1 _$ 2% binder = 40%, pigment = 26% pigmentation = 67%, flow time (4 mm nozzle) = 235 s, 258 s (6 Mon "), 305 s (12 months). After dilution of 100 parts of the product produced with 18 parts of ethyl glycol acetate / xylene, a moisture-drying varnish with 56 % pesticide, a flow time of 47 s and the following pendulum hardness according to TGL 107 / 061.01 = 20 s (1 day), 89 s (7 Days), 153 s (3 h at 120 ^° C.) ₀

Example 9

The procedure is as in Example 8, but using a trituration consisting of 42 parts Permanentrot R extra, 150 parts of ethyl glycol acetate, 150 parts of xylene, 300 parts of the polyester alcohol of Example 2 and 1.5 parts II. The reaction product has a content of 58 % pesticides and an expiry

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time of 140 s, pendulum hardness after. TGL 107 / 061.01 = 53 s (2 days), 140 s (7 days).

Example 10.

Are employed 158 parts of toluene diisocyanate 80/20 in 146 parts of ethyl glycol acetate / xylene at 50 ⁰ C with a grind of 270 parts of the polyester alcohol of Example 2, 196 parts of red iron oxide, 100 parts of ethyl glycol acetate, 150 parts of xylene, 4 parts of zinc bis- (2- Hydroxyethoxyethylmaleat (50% in ethyl glycol acetate, III) and 5 parts Triethylorthofonniat and receives a storage-stable pigmented prepolymer with the following data: pesticide = 63 % , flow time = 120 s, pendulum hardness according to TGL 107 / 061.01 = 77 s (1 day), 140 s (7 days).

Claims (4)

- 11 - 2 17921 Erfindungsansprjiche 1. Verfahren zixr Preparation of storage-stable polyurethane one-component paints, consisting of hydroxyl and amino group-free solvents and reaction products of di- or polyisocyanates with branched or * linear. Polyalcohols !!, characterized in that the reaction at temperatures of 10 to 60 ⁰ C, preferably 20 to 50 ⁰ C in the presence of hydroxy-functional organometallic catalysts of the following structures I to IV before M ¹¹ 4 (I) ₉ R ₃ ^ _n M ¹¹¹ R * (ID »Vn ^{lIV R} n R _5-11 M ^ R ^ (IV), where R is any alkyl, cycloalkyl or aryl residue • t and R is any hydroxy-functional organic radical having a hydroxyl group in alcoholic bond _o 2 «method according to item 1, characterized in that polyalcohols are used which contain dispersed commercial pigments. 3 «method according to item 1 and 2, characterized in that it is preferably used as the isocyanate component isophorone diisocyanate or its low molecular weight reaction products * .4 * Method according to item 1 to 3, characterized in that the stoichiometric ratios are chosen so that. the equivalence ratio IICO / OH is between 1.5 and 2.1