DE1128647B - Process for the production of plastics by the isocyanate polyaddition process - Google Patents

Description

Process for the production of plastics by the isocyanate polyaddition process Blocked isocyanates are used in particular in the production of coatings and stoving enamels and the like by the isocyanate polyaddition process. Only in the heat by splitting off a blocking component, usually phenols, Isocyanate groups set free.

It is known to produce isocyanates from amines and phosgene, be it it in a continuous or discontinuous process. In in the Technique customary process is doing the resulting isocyanate subsequently distilled in vacuo to improve its purity. A distillation residue remains, its amount 5 to 300 / o of the amine used, depending on the type of starting material and the phosgenation method. The chemical composition of this Distillation residue is not certain, but it is believed that the residue Higher molecular weight urea derivatives are present. Have the arrears so far found no practical use.

The invention relates to a process for the production of plastics according to the isocyanate polyaddition process from compounds with at least two reactive Hydrogen atoms and isocyanate cleavers with shaping, which is characterized by is that the monohydric phenols are heated to temperatures above 100 "C, remaining in the distillation of isocyanates obtained from amines and phosgene Distillation residues used as isocyanate releasers.

In this way, the distillation residue, which was previously considered waste, is removed put to useful use. It can be the distillation residues use any isocyanates obtained from the associated amine and phosgene have been, so z. B. Distillation residues from the production of hexyl isocyanate from hexylamine, cyclohexyl isocyanate from cyclohexylamine, phenyl isocyanate from aniline, Furfuryl isocyanate from furfurylamine, tetramethylene diisocyanate from tetramethylene diamine, Pentamethylene diisocyanate from pentamethylene diamine, hexamethylene diisocyanate from hexamethylene diamine, Octamethylene diisocyanate from octamethylene diamine, undecamethylene diisocyanate from undecamethylene diamine, Dodecamethylene diisocyanate from dodecamethylene diamine, 3,3'-diisocyanatodipropyl ether from 3,3'-diaminodipropyl ether, xylylene diisocyanates from xylylene diamines, diphenylmethane-4,4'-diisocyanate from 4,4 'diaminodiphenylmethane, 2,2-diphenylpropane-4,4'-diisocyanate from 2,2-diphenylpropane-4,4'-diamine, p-isocyanatobenzyl isocyanate from p-aminobenzylamine, m-phenylene diisocyanate from m-phenylenediamine, p-Phe- nylenediisocyanate from p-plienylenediamine, 2,4-tolylenediisocyanate from 2,4-tolylenediamine, 2,6-ToWlen diisocyanate from 2,6-tolylenediamine, naphthylene-1,4-diisocyanate from naphthylene-1,4-diamine, Naphthylene-1,5-diisocyanate from naphthylene-1,5-diamine, 1,3,5-benzene triisocyanate 1,3,5-benzenetriamine, 2,4,4'-triisocyanatodiphenyl ether from 2,4,4'-triaminodiphenyl ether or furfurylidene diisocyanate from furfurylidenediamine.

The modified distillation residues of aromatic isocyanates are particularly suitable as starting material for the present process.

Monohydric phenols are preferably those of the general formula in which R is a hydrogen atom or an alkyl group and n is an integer from 1 to 5. Examples include phenol, o-, m- and p-cresol, o-, m- and p-ethylphenol, o-, m- and p-ethylphenol, o-, m- and p-propylphenol, o-, m- and p-propylphenol, o-, m- and p-isopropylphenol, o-, m- and p-butylphenol, o-, m- and p-isobutylphenol, o-, m- and tert-butylphenol, o-, m- and undp-amylphenol, o-, m- and undp-isoamylphenol, o-, m- and p-tert-amylphenol; 2,3-xylenol, 3, SXylenol, 2,6-xylenol, 2,4-xylenol, 3,5-xylenol, 2,5-xylenol, 2,3-diethylphenol, 3,4-diethylphenol and 2,6- Diethylphenol; 2,4-diethylphenol, 3,5-diethylphenol and 2,5-diethylphenol; 2,3-dipropylphenol, 3,4-dipropylphenol, 2,6-dipropylphenol, 2,4-dipropylphenol, 3,5-dipropylphenol and 2,5-dipropylphenol; 2,3 Isopropylphenol, 3,4-diisopropylphenol, 2,6-diisopropylphenol, 2,4-diisopropylphenol, 3,5-diisopropylphenol and 2,5-diisopropylphenol; 2,3-diisobutylphenol, 3, 4-diisobutylphenol, 2,6-diisobutylphenol, 2,4-diisobutylphenol, 3,5-diisobutylphenol and 2,5-diisobutylphenol; 2,3-dibutylphenol, 3,4-dibutylphenol, 2,6-dibutylphenol, 2,4-dibutylphenol, 3,5-dibutylphenol and 2,5-dibutylphenol; 2,3-di-tert.butylphenol, 3, SDi-tert.butylphenol, 2,6-di-tert.butylphenol, 2, di-tert.butylphenol, 3,5-di-tert.butylphenol, and 2,5-di-tert.butylphenol ; 2-methyl-3-ethylphenol, 2-methyl-6-ethylphenol, 3-methyl-4-ethylphenol, 2-methyl-4-ethylphenol, 3-methyl-5-ethylphenol, 2-methyl-5-ethylphenol, 2-propyl -3-butylphenol, 3-ethyl-5-isobutylphenol or 3-ethenyl-4-propylphenol.

The manufacture of the starting material, on its manufacture no protection is claimed at this point, it is expediently carried out in such a way that one the distillation residues in the monohydric phenol in molten or solid Form, depending on the temperature used. The melting temperature of the residues is generally 170 to 230 ° C.

The residues become melted immediately after they are received Form used, so it is advantageous to use them in a larger amount of monovalent Give phenol, as these often boil below the melting point of the residue to have. Otherwise, however, the order of addition to the reaction mixture is not decisive. Solid distillation residues are expedient before use ground. You can then dissolve them in the phenol or by means of comminute in a ball mill after entering into the phenol.

During the reaction, the temperature rises due to the reaction of the NCO groups present in the residue with the phenol. The reaction mixture is for 1 Heated for up to 6 hours, expediently to 100 to 150 "C. It may be appropriate to use the then filter the resulting solution to remove undissolved particles. The clear, dark filtrate contains a blocked isocyanate with the monohydric phenol as a solvent. The viscosity of the solution can vary from more than 100,000 cP down to about 200 cP. It is of course related to the amount of phenolic Solvent. As the amount of solvent increases, the viscosity naturally decreases of the reaction solution obtained and its NCO content in the unit volume.

The examples show the use of the blocked isocyanates for Production of coatings and stoving enamels. As connections with at least two reactive hydrogen atoms serve z. B. polyhydroxyl compounds, such as the usual known polyester and polyether. In the case of stoving enamels, turn with advantage temperatures of 125 to 250 ° C in a period of 15 minutes to 2 hours. In particular, one can use the inventive masked according to to be used Isocyanates also react with coal tar pitch, whereby one has a hard, but flexible black coating.

The process products can also be made into coatings with polyamide resins, process with pigments and fillers if necessary.

Production of the starting material A 280g of the solid distillation residue from the production of toluene diisocyanate by phosgenation of toluene diamine are brought together with 860 g of a crude mixture of o-, m- and p-cresol. Heat develops, which is a reaction of the NCO groups in the distillation residue with the hydroxyl groups of the cresol.

The temperature of the mixture is brought to 135 "C and with stirring held for 2 hours.

The solution is then cooled to room temperature and filtered to remove any undissolved material to remove. The result is a viscous, blocked isocyanate, dissolved in cresol, with 1.4% NCO groups.

The blocked isocyanate obtained can before filtering with the the same amount of cresol should be diluted to facilitate filtration. The clear dark filtrate has 0.70 / o NCO groups. This corresponds to 5.75% of the weight of Tolylene diisocyanate and distillation residue, calculated as NCO groups.

Preparation of starting material B 280 g of a molten distillation residue from the production of toluene diisocyanate by phosgenation of toluene diamine are slowly added to 1500g of a mixture of xylenol and cresol. The melting point the residue is about 180.degree. After everything has been put together, will the reaction mixture is kept at 140 ° C. for 3 hours. The result is a capped Isocyanate in a xylenol-cresol solution.

Example 1 100 parts by weight of a polyester (acid number 2) 0.5 moles of phthalic anhydride, 2.5 moles of adipic acid and 4 moles of glycerol are added to 2400 Parts by weight of the blocked isocyanate "A" implemented. The solution obtained is applied to a metal base and baked for 1/2 hour at 175 "C. The result a hard, dark brown film coating.

Example 2 100 parts by weight of coal tar pitch are mixed with 70 parts by weight of the blocked isocyanate x> A «added. The resulting solution is on a Backing applied and baked for 1 hour at 155 "C. The hard, black coating is suitable as a primer in the automotive industry.

Claims (1)

PATENT CLAIM: Process for the production of plastics according to the Isocyanate polyaddition process from compounds with at least two reactive Hydrogen atoms and isocyanate cleavers below Shaping, thereby characterized in that the monohydric phenols are heated to temperatures above 100 ° C heated isocyanates obtained in the distillation of amines and phosgene remaining distillation residues are used as isocyanate releasers Into consideration Extracted publications: German Auslegeschrift No. 1 013 869; USk patent No. 2 801 990. Older patents considered: German Patent No. 1 089 160.