Process for preparing and optionally chain extending aqueous polyisocyanate dispersions using static mixers

• US 5,221,710 A
• Filed: 03/28/1991
• Issued: 06/22/1993
• Est. Priority Date: 03/28/1991
• Status: Expired due to Fees

• Current Assignee: Miles, Inc. (Bayer AG)
• Original Assignee: Miles, Inc. (Bayer AG)
• Inventors: Markusch, Peter H., Mason, Arthur W., Tirpak, Robin E.
• Primary Examiner(s): Michl, Paul R.
• Assistant Examiner(s): NILAND, PATRICK DENNIS
• Application Number:
  US07/677,002
• Time in Patent Office: 817 Days
• Field of Search: 524/591, 524/839, 528/68
• US Class Current: 524/591
• CPC Class Codes: C08G 18/0804 Manufacture of polymers containing ionic or ionogenic groups
• CPC Class Codes: C08G 18/0866 the dispersing or dispersed phase being an aqueous medium
• CPC Class Codes: C08G 18/5042 containing ureum groups
• CPC Class Codes: C08G 18/706 the liquid medium being water
• CPC Class Codes: C08G 18/8038 with compounds of C08G18/3225
• CPC Class Codes: C08G 18/8041 with compounds of C08G18/3271

Abstract

The present invention is directed to a process for preparing an aqueous polyisocyanate dispersion which has an isocyanate content of at least 0.5% by weight by

a) introducing an aqueous medium into a static mixer,

b) introducing a polyisocyanate into the static mixer,

c) mixing the polyisocyanate with the aqueous medium in the static mixer and

d) withdrawing the aqueous polyisocyanate dispersion from the outlet of the static mixer,

e) introducing the aqueous polyisocyanate dispersion into the inlet of a second static mixer,

f) introducing into the same of a different inlet of the second static mixer a chain extender containing at least a primary or secondary hydroxy monoamine and/or a polyamine having primary and/or a polyamine having primary and/or secondary amino groups

g) mixing the chain extender with the aqueous polyisocyanate dispersion in the second static mixer,

h) withdrawing the reacting mixture of the aqueous polyisocyanate dispersion and the chain extender from the outlet of the second static mixer and

i) allowing the polyisocyanate and chain extender to react to form the aqueous modified polyisocyanate dispersion.

Claims

1. A process for preparing an aqueous, polyisocyanate dispersion which has an isocyanate content of at least 0.5% by weight, based on the weight of the polyisocyanate, and is prepared by a process which comprises

a) introducing an aqueous medium into an inlet of a static mixer,

b) introducing a polyisocyanate which has an isocyanate content of at least 12% by weight into the same or a different inlet of said static mixer,

c) mixing said polyisocyanate with said aqueous medium in said static mixer,

d) withdrawing said aqueous polyisocyanate dispersion from the outlet of said static mixer,

e) introducing said aqueous polyisocyanate dispersion into the inlet of a second static mixer,

f) introducing into the same or a different inlet of said second static mixer a chain extender containing at least one of

i) a primary or secondary monoamine containing at least one hydroxyl group in an amount sufficient to provide an equivalent ratio of amino groups to isocyanate groups of 0.1:

1.0 to 0.7;

1.0 and

ii) a polyamine having primary and/or secondary amino groups and a molecular weight of 400 or less in an amount sufficient to provide an equivalent ratio of amino groups to isocyanate groups of 0.1;

1.0 to 0.4;

1.0, provided that when components i) and ii) are both mixed with the dispersed polyisocyanate, the equivalent ratio of amino groups from both components i) and ii) to isocyanate groups does not exceed 0.95;

1.0,

g) mixing said chain extender with said aqueous polyisocyanate dispersion in said second static mixer,

h) withdrawing the reacting mixture of said aqueous polyisocyanate dispersion and said chain extender from the outlet of said second static mixer and

i) forming a film of the reacting mixture while the NCO content is at least 0.5% by weight.

2. The process of claim 1 wherein said dispersed polyisocyanate is rendered hydrophilic by reaction with a compound containing a lateral or terminal nonionic hydrophilic group.

3. The process of claim 1 wherein said chain extender comprises a primary or secondary monoamine which corresponds to the formula ##STR3## wherein R₁ represents hydrogen or an alkyl, cycloalkyl, araliphatic or aromatic group having up to 15 carbon atoms,

R₂ is an optionally branched alkylene group containing 1 to 12 carbon atoms, m represents 0 or 1, n represents 1 or 2 and

m+n=2.

4. The process of claim 3 wherein

R₁ is an alkyl group containing 1 to 6 carbon atoms and

R₂ is an optionally branched alkylene group containing 1 to 4 carbon atoms.

5. A process for preparing an aqueous, polyisocyanate dispersion which has a functionality of at least 2 and an isocyanate content of at least 1.0% by weight, based on the weight of the polyisocyanate, and is prepared by a process which comprises

a) introducing an aqueous medium into an inlet of a static mixer,

b) introducing into the same or a different inlet of said static mixer a polyisocyanate which has an isocyanate content of at least 12% by weight and is rendered hydrophilic by reaction with a compound containing a lateral or terminal nonionic hydrophilic groups,

c) mixing said polyisocyanate with said aqueous medium in said static mixer,

d) withdrawing said aqueous polyisocyanate dispersion from the outlet of said static mixer,

e) introducing said aqueous polyisocyanate dispersion into the inlet of a second static mixer,

f) introducing into the same or a different inlet of said second static mixer a chain extender containing at least one of

i) a primary or secondary monoamine containing at least one hydroxyl group in an amount sufficient to provide an equivalent ratio of amino groups to isocyanate groups of 0.1:

1.0 to 0.7;

1.0 and

ii) a polyamine having primary and/or secondary amino groups and a molecular weight of 400 or less in an amount sufficient to provide an equivalent ratio of amino groups to isocyanate groups of 0.1;

1.0 to 0.4;

1.0, provided that when components i) and ii) are both mixed with the dispersed polyisocyanate, the equivalent ratio of amino groups from both components i) and ii) to isocyanate groups does not exceed 0.95;

1.0,

g) mixing said chain extender with said aqueous polyisocyanate dispersion in said second static mixer,

h) withdrawing the reacting mixture of said aqueous polyisocyanate dispersion and said chain extender from the outlet of said second static mixer and

i) forming a film of the reacting mixture while the NCO content is at least 1.0% by weight.

6. The process of claim 5 wherein said chain extender comprises a primary or secondary monoamine which corresponds to the formula ##STR4## wherein R₁ represents hydrogen or an alkyl, cycloalkyl, araliphatic or aromatic group having up to 15 carbon atoms,

R₂ is an optionally branched alkylene group containing 1 to 12 carbon atoms, m represents 0 or 1, n represents 1 or 2 and

m+n=2.

7. The process of claim 6 wherein

R₁ is an alkyl group containing 1 to 6 carbon atoms and

R₂ is an optionally branched alkylene group containing 1 to 4 carbon atoms.