DE1249426B - Process for the production of coatings, paints, impregnations, gluing or enamelling - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY Int. Cl .:

C09d

GERMAN

C O 9 D 17 5/00 '-

PATENT OFFICE

EDITORIAL German class: 22 h - 3 -CC Q " ° /

Number:
File number:
Registration date:
Display day:

1249 426 F43814IVc / 22h August 24, 1964 September 7, 1967

The production of coatings, paints, adhesive bonds, impregnations and stoving finishes by the isocyanate polyaddition process is known. Polyhydroxyl compounds and masked polyisocyanates are often used as polyaddition components, in which, as is known, the reactive isocyanate groups are sealed with monofunctional compounds that split off again when heated and release the isocyanate groups, which can then react with the hydroxyl groups of the countercomponent. In this way, durable mixtures of polyhydroxyl compounds and polyisocyanates are obtained which can easily be applied as flat structures. The nip temperature is generally about between 150 and 200 ⁰ C. Owing to the addition of tertiary amines or salts of tertiary amines, the cracking temperature can be significantly lowered, but a slow gaps then takes place already at room temperature, whereby the actual meaning of the use blocked polyisocyanates is destroyed.

The present invention teaches overcoming these disadvantages and relates to a method of manufacture of coatings, paints, impregnations, gluing or stove-enamelling Heat reaction of polyhydroxyl compounds with blocked polyisocyanates. The procedure is through characterized in that the polyhydroxyl compounds are blocked with polyacyl isocyanates implements.

In addition, the content of catalyst in the finished product has a detrimental effect on its durability a.

The surprising observation was made that polyhydroxyl compounds and blocked polyacyl isocyanates in mixtures or solutions which can be stored unchanged at room temperature ^{react with crosslinking at temperatures from 90 to HO 0} C without the addition of catalysts. The low splitting temperatures result in a considerable simplification of the processing technology for the production of paints, bonds and stoving finishes.

In addition, paints and coatings based on polyhydroxyl compounds and masked stand out aromatic polyacyl isocyanates are characterized by very good lightfastness.

In particular, the masked polyacyl isocyanates are used Reaction products of polyacyl isocyanates with phenol or cresol or condensation products of acid chlorides with Process for the production of coatings, paints, impregnations, bonds or stove enamelling

Applicant:

Paint factories Bayer Aktiengesellschaft, Leverkusen

Named as inventor: Dr. Wolfgang Kleben, Dr. Erwin Müller, Leverkusen; Dr. Wilhelm Thoma, Cologne-Flittard

Phenyl or cresyl urethanes or condensation products of acid amides with phenyl chloroformate or cresyl ester.

Blocked polyacyl isocyanates which are suitable for the present process include, for example named the following compounds:

I. A - CO - A

A = - NH-COO-OiH ₅ or -NH- COO - C ₆ H ₄ - CHs

II. A - CO - CO - A

III. A-CO- (CHa) _n -CO-A η = 1 to 8

IV. A-CO

CO -A

A - CO CO - A VH. Cl- <f V-CO - A

A-CO

709 640/547 I.

CH ₃

TX. A-CO

CO -A

CO -A

A-CO

XII. A - CO

CO -A

CO -A

IO XIII. A-CO-CH ₂ O

OCH ₂ - CO - A

XIV. A - CO - CH ₂ - CH ₂ O

OCH ₂ - CH ₂ - CO - A

by methods known per se, such as, for example, by condensation of acid chlorides with Phenyl urethane or by reacting acyl isocyanates with phenol or cresol, accessible are.

The polyacyl isocyanates blocked with phenol or cresol will preferably be used in the process according to the invention. In principle, however, it is also possible to use other isocyanate releasers, such as i. B. the reaction products of polyacyl isocyanates with malonic ester, acetoacetic ester or caprolactam.

Also those blocked polyacyl isocyanates, which, for example, by adding 3 mol of one Acyl diisocyanates obtained on 1 mole of trimethylolpropane and subsequent reaction with 3 moles of phenol are ideally suited for the present process.

CH ₂ - OCONH - CO iC - CH ₂ - C - CH ₂ - OCONH - CO CH ₂ - OCONH - CO

- CO - NHCOOC ₆ H ₅
CO-NHCOOC ₆ Hs
CO - NHCOOC ₆ H ₅

The polyhydroxy compounds used are those customary for the production of coatings by the isocyanate polyaddition process Common polyesters, polyethers, polyacetals. Polythioethers, polymers and partially acylated cellulose, hydrogenated Phenol - formaldehyde condensation products used.

The polyhydroxy compounds and the blocked polyacyl isocyanates are preferred in such Amounts used such that the ratio of OH to NCO groups is from 1: 0.5 to 1: 1. By By varying the proportions, it is possible to change the film properties of the coating from hard-brittle affect up to soft-rubber-elastic.

The reaction can be carried out in solvents. As such, they are anhydrous solvents suitable, such as B. toluene, benzene, ethyl acetate, butyl acetate, cyclohexane, dimethylformamide, acetone, Methyl ethyl ketone, methyl glycol ether acetate, dioxane.

When working in solvents, the solids content of the solutions should be adjusted so that the Viscosity of the solution allows cheap processing to be coated. As a guide it should be said that the solutions are generally 10 to 50%, based on the sum of the polyhydroxyl compound and polyacyl isocyanate. The process according to the invention is used in particular to produce stoving finishes.

example 1

In 250g of a 10% solution of cellulose-2 ^! / 2- <icetate in acetone, a solution of 2.5 g of phenyl carbonyl bis-carbamate is mixed into 20 ml of acetone. The crosslinking agents containing cellulose 2 is poured to form coatings on glass plates ^1/2 acetate; these were ^{heated to 110 °} C. for 60 minutes. The coatings are then completely insoluble in acetone; B. after several days of storage in acetone not their shape.

Preparation of the binder for example I.

The carbonyl-bis-carbamic acid phenyl ester serving as the starting material for the process according to the invention was obtained in the following way:

100 g of phosgene are introduced into 80O g of benzene with cooling; it is added dropwise to this solution with further cooling 16Og pyndine. Tn this Originally, 274 g of phenyl carbamic acid are entered in the solid state. The reaction mixture is then refluxed for 1 hour.

After cooling, the precipitate formed is filtered off with suction, washed out with water and removed Recrystallized alcohol; Mp 152 ° C.

Example 2

Analogously to Example 1 250 g of a 10 ⁽⁾ / o Cellulose-2 ^1/2-acetate solution 2.5 g of oxalyl-bis-carbamidsäurephenylester dissolved in 10 g of dimethylformamide was added. As in Example 1, a coating is produced from the solution. ^{After heating to RO 0} C for 1 hour, this has become completely insoluble in acetone; it retains its shape even after several days of storage in acetone.

Preparation of the binder for example 2

The oxalyl-bis-carbamic acid phenyl ester serving as starting material for the process according to the invention was obtained as follows:

63.5 g of oxalyl chloride are dissolved in 400 g of benzene and 80 g of pyridine are added dropwise with cooling. To after the introduction of 140 g of phenyl carbamic acid, the reaction mixture is refluxed for 1 hour heated to boiling. After cooling, the solvent becomes the upper phase of the reaction product decanted. The reaction product, initially pulpy, is stirred three to four times with water. Included the reaction material solidifies and can finally be filtered off with suction and dried; Mp. 143 to 146 C.

Example 3

50 g of a polyester made from 2.5 mol of adipic acid, 0.5 mol of phthalic acid and 4 mol of l, l, l-tris (hydroxymethyl) propane (OH number 280; acid number 1) and 40 g of cresol-capped l-chlorine ^^ - phenylene dicarbonyl isocyanate are dissolved in 50 g of dimethylformamide. An iron sheet coated with this solution After 30 minutes of stoving at 120 "C, it receives a clear, elastic paint film.

Preparation of the binder for example 3

That as the starting material for the crusting size The blocked dicarbonyl isocyanate required for the procedure was obtained in the following manner:

50 g of l-chloro-2,4-phenylene-dicarbonyisocyanate and 44 g of raw cresol are dissolved in 200 ml of anhydrous Benzene reacted for 1 hour at 80 ° C. After cooling, the blocked diisocyanate can be seen as a white Powder, melting point 180 ° C. (Koflcr bench), suction off.

Example 4

It is made from 40 g of the polyester from Example 3, 50 g of 1,3-phenylene-dicarbonyl isocyanate capped with cresol and 50 g of dimethylformamide prepares a lacquer solution. Iron sheets made with this solution are coated, form after stoving for hours at 100 ° C a colorless, elastic coating.

The masked diisocyanate required as the starting material for the process according to the invention is analogous to that given in Example 3, from 324 g of 1,3-phenylene-dicarbonyl isocyanate and 325 g Raw cresol obtained, white powder; M.p. 140 to 142C (Kofler-Bank).

Example 5

40 g of one made from 1 mol of phenol and 0.75 mol of formaldehyde with the addition of a little hydrochloric acid as a catalyst produced condensation product are after the catalytic ^ hydrogenation in 50 g of methyl glycol acetate solved. The solution of 40 g of the 1,3-phenylenedicarbonyldnsocyanate blocked with cresol is then added from Example 4 and 40 g of dimethylformamide were added. One dips into this lacquer sheets, which after 30 minutes of baking at 100 ° C very hard and lightfast coatings obtained.

Example 6

50 g of a branched polyester made from 3 moles of adipic acid, 3 moles of l, ll-tris (hydroxymethyl) propane, 1 mole of butylene glycol (7% OH) and 40 g of the blocked diisocyanate from Example 4 are dissolved in 60 g of dimethylformamide. An iron plate coated with this lacquer receives a shiny, firmly adhering, elastic coating ^{after stoving for 30 minutes at HO 0 C.}

Example 7

50 g of the polyester from Example 3 and 50 g of adipoyl diisocyanate capped with cresol are dissolved in 50 g of dimethylformamide. The curing temperature of this resist solution is 120 to 13O ⁰ C, wherein very elatische, soft coatings can be obtained. The cresol-capped adipoyl diisocyanate required as starting material was prepared in the following way:

A benzolic solution which contains about 0.1 mol of adipoyl diisocyanate in 150 ml is refluxed with 27 g of crude cresol for 1 hour. It is allowed to cool, the cresyl urethane which has precipitated is filtered off with suction and washed with ether, white powder; Mp. 154 to 155 ^e C.

Claims (1)

Claim: Process for the production of coatings, paints, impregnations, bonds or Stoving enamels through the heat reaction of polyhydroxy compounds with masked polyisocyanates, characterized in that the polyhydroxy compounds are blocked with Reacts polyacyl isocyanates.