DE2724363C3 - Aqueous isocyanate emulsions for gluing chipboard - Google Patents

Description

The invention according to patent specification 27 03 271 relates to a process for the production of aqueous Polyisocyanate emulsions, the polyisocyanates in the presence of an emulsifier * based on a polyglycol with a molecular weight from about 4000 to 20,000, with the OH groups in the emulsifier being 40% or less of the NCO groups make up, dispersed or emulsified in water.

The invention relates to a further embodiment of the method according to the main patent by additionally 1 to 30 percent by weight, based on the polyglycol, of a polypeptide is used.

The subject of the patent is thus a process for the preparation of aqueous polyisocyanate emulsions by emulsifying or dispersing the polyisocyanates in water in the presence of emulsifiers based on a polyglycol with a molecular weight of about 4000 to 20,000, the OH groups in the emulsifier make up 40% or less of the NCO groups according to patent 27 03 271, characterized in that 1 to 30% of a polypeptide based on the polyglycol is also used.

Aqueous emulsions of polyisocyanates are formed which have a longer useful life than those obtainable according to the main patent and, moreover, are cheaper because less emulsifier is required for their production. In general, • sine amount of about 03-5% of emulsifier, based on the total emulsion weight sufficient to produce an emulsion whose litrierbarer content does not fall away more than about 3% of isocyanate groups in 10 hours to. The table below, which was drawn up with the emulsion of the preparation example, / Eigi dies.

Polypeptides in the context of the invention are, for example, gelatin. Bone glue and the like made from protein bodies winnable products, these are commercially available and do not require any further explanation. you will be preferably added to the emulsification water in the appropriate concentration and allow a high emulsification rate to. In general, the content of polyglycol in the emulsion is 1 to 10%, while 0.1 to 1% polypeptide is used,

Information on other details on the production and use of the polyisocyanate emulsions can be found in

ίο included in the description of the main patent to which referenced here.

example

A typical emulsion is made up of 38 parts technical Diphenylmethane-4,4'-diisocyanate (MDt) and 62 parts of 3.5% strength aqueous emulsifier solution in the following

Way to get:
It becomes a 3.5% solution of 0.5 parts of i ~ "-älatine

and 3 parts of a polyglycol in warm water. Be in 62 parts of the cooled solution 38 parts of diphenylmethane-4,4'-diisocyanate were stirred in.

Emulsification with a high speed stirrer takes about 10 to 15 seconds.

To determine the stability of the emulsion, the 2, isocyanate content is the same at the time of manufacture 100% set and the decrease measured continuously. This results in the 38% emulsion described only a decrease of 2.6% within 7 hours

Adhesive content.
The following table gives an overview of the averaged isocyanate contents for an emulsion of 38 parts of diphenymethane-4,4'-diisocyanate with 62 parts of 3.5% strength aqueous emulsifier solution.

> '> Table

hours

Isocyanate (%)

0
0.5

I.
2
3
4th
5
6th
7th

100.0
99.8
99.5
99.0
98.6
98.4
97.8
97.6
97.4

Application example

With her described emulsion, which means 5% Emulsifier solution had been obtained, particle board was produced in the usual way and their technological application checked.

Isdcyanal. 100% absolutely dry (aim) Spiinc

Plate test according to DIN 52 360-65
Flexural Strength (N / mm ')
Tensile strength wedge V 20 (kp / cm ² )
Transverse tensile strength V KK) (kp / cnv)
Swelling after 2 h (%)
Swelling after 24 h (%)

27 »

.1%

4%

21.2 23.4 26.2 .M 5.9 7.9 0.2 1.4 2.4 2.4 2.4 2.2 12.0 9.0 8.4

Claims (1)

Claim: Process for the preparation of aqueous polyisocyanate emulsions by emulsifying or dispersing the polyisocyanates in water in the presence of Emulsifiers based on a polyglycol with a molecular weight of about 4,000 to 20,000, where the OH groups in the emulsifier make up 40% or less of the NCO groups Patent 2703271, characterized in that 1 to 30% of one Polypeptides based on the polyglycol are also used.