DE2305695A1 - SURFACE COMPOSITIONS - Google Patents

Description

DR.-INC H. FT ¹ OK *.

DIPL -!.! *. I- '^;

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* MULL ENo I iiAi - U

"eppe 23109 -

Case Du 24-747 2305695

Imperial Chemical Industries Ltd. London, UK

Surface covering compositions

Priority: 02/10/1972 - Great Britain

The invention relates to two-component polyurethane n- ■ l-.cke based on certain aliphatic polyisocyanates, to a process for the production of surface coverings on substrates using these lacquers and on the coated substrates obtained in this way.

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Two-component paints in which an aromatic polyisocyanate is one component and a polymeric polyol, e.g. a hydroxyl-capped polyester, a hydroxyl-capped · closed polyesteramide or a hydroxyl-capped one Foly ethers, the second component, have been used for a long time used. The two components are used to produce the paint, usually with one or more solvents, mixed together just before the lacquer is applied to a substrate. The two components begin to react and cure immediately after mixing, a polyurethane surface covering being obtained on the substrate will. Polyisocyanates that are commonly used in such two-component systems are, for example Diphenylmethane - ^, 4 -'-diisocyanote, isocyanurate polymers of lolylene diisocyanates and adducts obtained by reacting excess tolylene diisocyanate with a low molecular weight Folyol or a polyol mixture, such as z = B. Trimethylolpropane, Glycerin, diethylene glycol, hexanetriols and butanediols, can be obtained. '

These two-component paints produce surface coverings that have many desirable properties, but have the disadvantage that they are exposed to prolonged exposure and turn yellow, especially when exposed to UV light. To some extent, this disadvantage can be overcome by that one'die aromatic diisocyanates completely or partially replaced by aliphatic polyisocyanates. It can also be used as an isocyanate component in a two-component system Isocyanurate copolymers of aliphatic polyisocyanates and aromatic polyisocyanates are used will. .

It has now been found that two-component paints, the polyurethane surface coverings with an improved

to give
_w _ _ _w / can be obtained if as

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Polyisocyanate component is a mixture of tolylene diisocyanate derivative isocyanurate polyisocyanate and from a. Isocyanate group-containing adduct of a low molecular weight Folyol and an excess of an aliphatic polyisocyanate is used.

Thus, according to the invention, a two-component polyurethane varnish is used proposed that of a polyisocyanate component and a polymeric polyol component, which are mixed together before application to a substrate, the polyisocyanate component of one Isccyanur-- tpolyisocyanate derived from tolylene diisocyanate and from an isocyanate group-containing adduct of a low molecular weight polyol and an excess of one aliphatic polyisocyanate.

By the term "low molecular weight PoIyöl" are aliph ^r itische compounds mit'2 to 6 carbon atoms and 2 to 4 hydroxyl groups and the reaction products thereof niedrignolekularen meant A'thylenoxid or Fropylenoxid. Examples of low molecular weight polyols are ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,3-, 1, ^ - and 2,3-butylene glycol, pentamethylene glycol, hexamethylene glycol, teopentylene glycol, glycerol, hexanetriols, trimethylolethane, trimethylolpropane and pentaerythritol. Mixtures of these compounds can also be used.

Examples of aliphatic polyisocyanates with the Low molecular weight polyols defined above can be used to prepare the adducts used in the present case Processes used are tetramethylene diisocyanate, hexamethylene diisocyanate, 2,2,4- and 2,4,4-triethylhexamethylene diisocyanate, Dicyclohexylmethane diisocyanBte

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and methylcyclohexylene diisocyanates. The preferred polyisocyanate is 3-isocyanatomethyl-3,5 »5-trimethylcyclohexyl isocyanate, which is also known as isophorone diisocyanate. Mixtures of these isocyanates can also be used.

The polyol / isocyanate adducts are prepared by known methods, expediently by slowly adding the low molecular weight polyol to a heated solution of the polyisocyanate in a suitable inert solvent, as defined below. Aliphatic isocyanates are considerably less reactive with hydroxyl groups than aromatic isocyanates, which is why a catalysis should be used so that the formation of the adduct takes place at a sufficient rate. The catalyst can be any of the compounds known to catalyze the reaction between isocyanate and hydroxyl groups. Suitable catalysts are, for example, organometallic compounds, metal salts and tertiary amines. Specific examples include dibutyl tin dilaurate, tetrabutyl titanate, zinc octoate, zinc naphthenate, tin (II) octoate, tin (IV) chloride, iron (III) chloride, lead octoate, potassium oleate, cobalt 2-ethylhexanoate, Ν, Ν -Dimethylcyclohexyl- ·? Min, ΙΤ, Ιν-dimethylbenzylamine, IT-ethylmorpholine, 1,4-diazabicyclo-2,2,2-octane, 4- dimethylaminopyridine, oxypropylated triethanolamines, ß-diethylaminoethanol and Ν, ΪΤ, ΙΤ ', N '-letrskis (2-hydroxypropyl ethylenediamine. The isocyanate must be used in excess to polyol to ensure that the adduct contains free isocyanate groups. The ITCC: GE ratio in the preparation of the adducts should be at least 1.2: 1.0 and up to 3? 5 ^: "i> 0 or more.

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The isocyanurate polyisocyanate is part of the polyisocyanate component which is used in the present process is obtained by Tolylene diisocyanate in the presence of catalysts known to be. they the formation of isocyanurate systems promote, polymerized. For example, the tolylene diisocyanate can either be used alone or in a suitable one inert solvents are heated with a basic catalyst, such as z.3. with an aliphatic tertiary amine, a basic metal compound, for example alkali or alkaline earth metal oxides, hydroxides, carbonates, alcoholates or phenates, an alkali metal derivative an enolizable compound or a metal salt of a weak organic acid. Cocate lysers, such as 3. Alcohols, phenols, mono-N-substituted carbamic acid esters or cyclic oxides can also be used.

Tolylene diisocyanate means tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate or a mixture thereof, in particular the commercially available mixtures of these isomers, such as 3. that which 8C parts of the 2,4-isomer and 2C contains parts of the 2,6-isomer, or that which 65 parts of the 2,4-isomer and 35 parts of the 2,6-isomer contains. The catalyst used in the production of the isocyanurate polymers can by adding an acidic compound, such as 3. Phosphoric acid, or HCl, can be neutralized. · In cases where the addition of acids the If the formation of an insoluble salt results, this can be removed by filtration. The isocyanurate polymers are preferably largely free of unreacted tolylene diisocyanate, which if necessary by extraction with a solvent, by thin film distillation or by Treatment with adsorbents such as carbon or Silicon dioxide, can be removed.

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The polyisocyanate component is obtained in that the isocyanurate polyisocyanate and the adduct of aliphatic polyisocyanate and polyol in weight " Mixes ratios that are generally in the range of 9: 1 to 1: 2; but there can also be relationships outside this area can be used if necessary.

The polymeric polyethylene component of the invention Two component paints can be any of the hydroxyl capped polyesters, polyester amides, or polyethers be commonly used in the manufacture of polyurethanes be used.

Examples of suitable hydroxyl-capped polyesters and polyesteramides are those obtained by known methods from carboxylic acids, glycols and if necessary smaller amounts of diamines or amino alcohols can be obtained. Suitable. Dicarboxylic acids are amber, glutar, Adipic, cork, azelaic, sebacic, phthalic, isophthalic and terephthalic acids and mixtures thereof. examples for Dihydric alcohols are ethylene glycol, 1,2-propylene glycol, 1,3-3utylene glycol, 2,3-butylene glycol, diethylene glycol, Tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, Decamethylene glycol and 2,2-dimethyltrimethylene glycol. Suitable diamines or amino alcohols are, for example, hexamethylene diamine, ethylene diamine and monoethanolamine and phenylenediamines. Mixtures of polyesters and polyester amides can also optionally be used will. Smaller amounts of polyhydric alcohols, such as glycerine, irimethylolpropane or pentaerythritol, can also be used, in which case branched polyesters and polyesteramiles are obtained. ·

Examples of hydroxy-terminated Folyäther that can be _{used; i} are Folymere and Kiscopolymere of

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cyclic oxides, such as ζ.3. 1,2-Alkylenoxiaen, for example ethylene oxide, epichlorohydrin, 1,2-propylene oxide, * , 2-3utylene oxide and 2,3-butylene oxide, Cxycyclobutan and substituted Cxycyclobutanen and tetrahydrofuran. For example, foly ethers should also be mentioned, which are obtained by polymerizing an alkylene oxide in the presence of an acidic catalyst and water, glycerine or a primary monoamine. Mixtures of such foly ethers can also be used.

The paints also know that they contain a solvent is inert to isocyanate groups, such as e'-en Ester, a ketone, a hydrocarbon or a halogenated hydrocarbon. Suitable solvents are for example ethyl acetate, butyl acetate, 2-i'thoxyäthylacet & t, Methyl ethyl ketone, kethyl isobutyl ketone, ^ -riethoxy - ^ - methylpentan-2-one, toluene and xylene. Mixtures of solvents can also be used. Either or both can be used Paint components are made using a solvent, which is then mixed in by mixing the Components obtained paint is incorporated.

The two paint components can be used in such proportions that the NGO: OK ratio is in the range from C, 7: "', C to 1.2: 1.0. It is preferred that the IiCO: OH ratio. is approximately 1: 1, so no significant Excess of isocyanate groups over hydroxyl groups or vice versa is present.

It would have been expected that surface supplements in which the hardening agents consist of compatible mixtures of aromatic and aliphatic polyisocyanates would show a color development when exposed to UV light, the intensity of which is between that obtained with the sole use of aromatic polyisocyanates,

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and those that -characteristic "for toppings on the Is based on aliphatic polyisocyanates. Ξ3 However, it has been found that when using mixed polyisocyanates as curing agents according to the Invention, an improvement in the color stability of a covering produced therefrom is obtained which is greater is than would be expected if the amount of yellowing is directly proportional to the (or proportional to the Logarithm of the) concentration of the yellowing, i.e. aromatic component ^ is.

The lacquers can be applied to the substrates by spraying, brushing, dipping, flowing or rolling. Other components such as pigments, fillers, leveling agents, e.g. nitrocellulose, ethyl cellulose or cellulose acetobutyrate, or other polymeric materials can be added prior to application. It is desirable that such additives be dried, if necessary, before they are incorporated into the composition of the invention be incorporated.

The drying speed of the paints can be increased by adding of catalysts for the isocyanate / hydroxyl reaction (as defined above) can be increased, but the use of such catalysts decreases the open Time of L = LCke. Examples of suitable substrates are Wood, rubber, metals, glass, textiles, leather, linoleum, paper and polymeric materials such as polyamides and Polyvinyl chloride.

The invention is further illustrated by the following examples explains where the parts and percentages are by weight are expressed.

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example 1 A. Making an adduct

To a solution of 600 parts of isophorone diisocyanate and 0.3 parts of dibutyl tin dilaurate in 708 parts of dry butyl acetate are added portionwise min bai a temperature of 70 C ^c IGS parts of trimethylolpropane during 45 wherein the reaction is carried out under a Stickstoffatnosphäre. After heating for a further 2 hours, the isocyanate content of the mixture falls to 8.6% (solids content of the mixture 50%). This product is called Solution A.

3. Preparation of an isocyanurate polymer

A solution of 40 parts of tolylene diisocyanate with a 2,4- and 2,6-i _{sonerenverältnis} of 65:35 in 60 parts of butyl acetate is in the presence of 0.18 part of a solution of calcium octoate in mineral spirits (the calcium octoate solution contains 5% Ca) and 0.1 part of phenol is heated as a cocatalyst until the isocyanate content of the mixture has fallen to 5.8%. The product is referred to as solution B.

C. Preparation of an adduct / isocyanurate mixture

Different proportions of solutions A and B are ^{mixed at 25 °} C., and the concentration of the solids in each mixture is adjusted to 4 ° C. by adding butyl acetate. The weights used and the composition of the mixtures are shown below:

ORIGINAL INSPECTED 309833/1055

solution A
(Parts) Solution b
(Parts) Butyl acetate, too
given "to the
Mix on 4G #
Solids' to
bring (parts) NGC content
of
Mixture 30th
50
70 70
. 50
30th 7.5
12.5
17.5 6.19 - - - .. "
6.45
6.71

D. Manufacture of paints

A leak was prepared from a 5 NC: 5O mixture of solutions A and B as the isocyanate component and from Eexantriol, _t · 'adipic acid and phthalic acid derived branched polyester having a hydroxyl value of 280 mg KGH / g and an acid value of 3 rag KOH / g manufactured as a polymeric polyethylene component.

10 parts of the 5G: 5O mixture of solutions A and 3, 7 * 8 parts a 4G% solution of the branched polyester mentioned above in methyl isobutyl ketone / cyclohexanone (4: 1) and 0.01 part of dibutyl tin dilaurate were mixed together, and the resulting clear solution was applied as a thin film on a tin plate. It became a hard clear one Film obtained, which is complete after 60 minutes in air at 25 ° C was tack free. Subject to a week's aging, the film was placed under a UV lamp for a week. He was then compared visually to a similar film that had not been exposed to the UV lamp. It wasn't a significant difference in color between the exposed and the unexposed film.

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Example 2

Sin varnish was made from a 7O: 5G mixture of readings A and B (Example 1) as an isocyanate component and from one derived from i, 3-3utanediol, eexanetriol and adipic acid Polyester with a hydroxyl value of 175 Eg rCCH / g and an acid value of 3 mg KGE / g as a polymeric polyol component manufactured.

10 parts of the 7O: 3G mixture of solutions A and B, 4.8 parts a 4G # Lgen solution of the above-mentioned polyester in Kethyl-isobutyl-ketone / cyclohexanone (4: 1) and G, v '. part Dibutyl tin dilaurate were mixed together and the obtained solution was applied to a tin plate. It turned out to be a hard film with properties similar to obtained in Example 1. In 2 hours it was so dry that it could be touched.

Example 5

A paint was made from a 3O: 7O mixture of solutions A and B (3 example 1) as the isocyanate component and from the example in 1 described polyester produced as a polymeric polyol component.

10 parts of the 3C: 7O mixture of solutions A and 3, 7i5 Parts of a 4C% solution of the polyester in methyl isobutyl ketone / cyclohexanone (4: 1) and G, 01 part dibutyltin dilaurate were mixed together, and the obtained Solution was then applied to a tin plate. It gave films with good strength and yellowing resistance. After 60 minutes at 25 ° C in air, these films were so dry that they could be touched.

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Quantitative Measurement of Gilts) Us 1.Making Films -

Varnishes are like. Prepared as follows: A suitable Henge Foljol is weighed and diluted with a calculated amount of solvent at which it is. a mixture of cyclohexanone / diethyl isobutyl ketone χει volume ratio of 1: 4 is. A weighed amount of hardener is added to this foliole solution and the mixture is instantly stirred into a homogeneous solution of Eusasmen. The amount of solvent added is calculated so that the paint has a total solids content of ^ -0% . The ratio of polyol to hardening agent is such that a GH / FCC ratio of 1: 1 results.

Once the varnish has been made a certain one will be Amount "of it poured onto a white porcelain tile and run evenly over the tile. The excess solution is drained by the tile is instantly brought into a vertical position. Then the solution is allowed to dry at room temperature. The" Films made in this way range in thickness from 15 to

The coated tiles are aged for 1 week at room temperature. They are then partially masked by covering the film with an opaque paper and placed in a box which is illuminated with the help of 4-Atlas Super UV lamps with 65 to 80 watts. The tiles are at a distance of 8.9 cm from the lamps. To prevent excessive heating, a flow of air is blown over the tiles with the help of a ventilator. A suitable exposure time with the UV light source is 1 week.

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2. measuring the extent of the yellowing

After the films on the white tiles have been irradiated with UV light as described above, the "energy efficiency index" is the exposed and non-exposed parts determined, being a Golormaster Model V (Meeco Instruments: described in bulletin CiI-12G0C) is used.

The yellowness index is calculated according to the formula given by the American Society for Testing Materials, Method ASTM D. 1925 ¹¹ A Standard Method of Test for Yellowness Index (Y) of Plastics. This calculation is based on the tristimulus values as in the ASTM -Method for data obtained on the Hardy GE Spectrophotometer (the Colorcaster Model V is an instrument that gives similar data).

The results are expressed as the Δ yellowness index. That is the difference in yellowness index between the exposed and non-exposed parts of the film.

The following example illustrates the results obtained in determining the Δ.yellowing index.

example

Lacquer v / urien on white porcelain tiles as described above using different ratios of the solutions A.urd B zuaunen with the polyester solution ϊοπ Example 1 produced. The isocyanate / hydroxyl reaction was ensured by the incorporation of O, Gi part of dibutyl-tin-dilaurate. ITafter hardening; during 1 week at Γ ^ ^c Z the filaments were partially covered and the above mentioned

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exposed to single ITV radiation. The yellowing index The exposed and non-exposed portions of each film are then processed using the Colormaster Kodell Y-Spectrophotometer measured, the results are given in the following table :,

relationship
of the solutions
A and B Weight of
Hardening
by means of Gev; icht des
Polyester A yellowness index
exposed-
not exposed 100: 0 10 - "8 _S 6 0.095 - 70:30 10 8.1 0.17 • 50:50 10 7 _S 8 0 _s 44 - 3C: 7G - 10 7.5 1.27 0: 100 10 7.1 14.76

The values of the A yellowness index are compared to the Concentration of the yellowing component B of the hardening agent applied? wherein the graph shown in Figure 1 Preserve representation x-zirdo- The non-linear relationship between the range of component B in the curing agent and the degree of yellowing of the film obtained is evident.

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Claims (9)

Claims 1. Two-component polyurethane paint containing a polyisocyanate component and a polymeric polyol component which is mixed together prior to application to a substrate are, characterized in that the FoIyisocyanatkonponente from an isocyanurate polyisocyanate derived from tolylene diisocyanate and from an isocyanate group containing adduct of a low molecular weight polyol and an excess of an aliphatic Polyisocyanate. 2. Varnish according to claim 1, characterized in that the aliphatic polyisocyanate from 3-isocyanatomethyl-3,5 »5-trimethylcyclohexyl isocyanate consists. 3 lacquer according to claim 1 or 2, characterized in that that the adduct of the low molecular weight polyol and the aliphatic polyisocyanate with the help of a Catalyst for the isocyanate / hydroxyl reaction has been prepared. 4. Paint according to one of claims 1 to 3, characterized in that the adduct with an NCO: OH ratio from 1.2 to 3.5 = 1.0 has been established. 5- Paint according to one of claims 1 to ^ _1, characterized in that the isocyanurate polyisocyanate and the adduct of aliphatic polyisocyanate and polyol are present in weight ratios of 9: 1 to 1: 2. 6. Lacquer according to one of claims 1 to 5, characterized in that it is also a solvent opposite Isocyan ^ .tgruppen is inert, contains. 309833/1055 7- lacquer according to one of claims 1 to 6, characterized in that the isocyanate component and the polymer Polyol component can be used in proportions that des ITQO: OH ratio ranges from 0.7 to 1.2: 1.0. S. Lacquer according to one of Claims 1 to 7 _5, characterized in that the isocyanate component and the polymeric film component are used in proportions such that the IiCO: CH ratio is approximately 1: 1. 9. Use of the paints according to one of the claims 1 to 8 for the production of surface coverings. 309833/1055