Process of making urea-formaldehyde solid microspheres

• US 3,928,272 A
• Filed: 03/25/1974
• Issued: 12/23/1975
• Est. Priority Date: 03/25/1974
• Status: Expired due to Term

• Current Assignee: Rheox, Inc. (Elementis PLC)
• Original Assignee: Daniel F. Herman, Jack J. Brancato
• Inventors: Herman, Daniel F., Brancato, Jack J.
• Primary Examiner(s): Foelak, Morton
• Application Number:
  US05/454,594
• Time in Patent Office: 638 Days
• Field of Search: 260/2.5B,2.5F,29.4R
• US Class Current: 528/232
• CPC Class Codes: C08J 2361/24 with urea or thiourea
• CPC Class Codes: C08J 3/09 in organic liquids
• CPC Class Codes: C08J 9/283 a discontinuous liquid phase emulsified in a continuous macromolecular phase
• CPC Class Codes: C08L 101/00 Compositions of unspecified macromolecular compounds
• CPC Class Codes: C08L 61/24 with urea or thiourea
• CPC Class Codes: C09D 7/42 Gloss-reducing agents
• CPC Class Codes: D21H 17/50 Acyclic compounds
• CPC Class Codes: D21H 19/42 at least partly organic
• CPC Class Codes: D21H 19/62 Macromolecular organic compounds or oligomers thereof obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: D21H 21/285 insoluble
• CPC Class Codes: D21H 21/54 being spherical, e.g. microcapsules, beads

Abstract

Spheroidal shaped microspheres of urea-formaldehyde have been prepared. These microspheres are regular in shape and have an average diameter which falls within the range of from 0.2 to 4 Mu . The surface area of these microspheres are from 10 to 90 m2/gm. When used as a filler in paper at a 6% loading in a No. 35/ream paper, the opacity is at least 82%. These spheroidal shaped microspheres of urea-formaldehyde are also readily dispersible in coating vehicles, paper coating compositions, latex paint formulations and solvent based polyester film-forming compositions. These microspheres are prepared by forming a water-in-oil emulsion in which the urea-formaldehyde prepolymer is dissolved in the water phase. The urea-formaldehyde is then polymerized to form the microspheres of the size mentioned above.

Claims

1. PREPARATION OF SPHEROIDAL SOLID SHAPED MICROSPHERES OF UREA-FORMALDEHYDE, SAID MICROSPHERES HAVING A SURFACE AREA OF FROM 10 TO 90 M2/GM, AND HAVING A DIAMETER RANGE FROM 0.2 U TO 4.0 U, WHICH COMPRISES ADMIXING WITH HIGH SHEAR AT A STEMPERATURE FROM 15*C. TO 40*C. AN AQUEOUS SOLUTION OF UREAFORMALDEHYDE PREPOLYMER AND A NON-SOLVENT CONTAINING AN EMULSIFYING AGENT TO FORM WATER DROPLETS IN A WATER-IN OIL EMULSION, SAID EMULSIFYING AGENT SELECTED FROM THE GROUP CONSISTING OF THE POLYMER OF ETHYL ACRYLATE GRAFTED ONTO POLYETHYLENE OXIDE AND THE SORBITOL ESTER OF LONG CHAIN FATTY ACIDS HAVING AN HLB BETWEEN 4.3 AND 8.6, SAID UREA-FORMALDEHYDE PREPOLYMER DISSOLVED IN THE WATER DROPLETS, ADDING AN ACID CATALYST TO THE EMULSION TO ADJUST THE PH TO FALL WITHIN THE RANGE OF FROM 2 TO 5 DURING WHICH TIME THE PREPOLYMER DISSOLVED IN THE WATER DROPLETS POLYMERIZES AND FORMS SPHERICAL SHAPED PARTICLES OF UREA-FORMALDEHYDE, AGAIN THE SUSPENSION FOR AT LEAST ONE HOUR, DILUTING THE SUSPENSION WITH WATER, ADDING A DISPERSING AGENT, SAID DISPERSING AGENT SELECTED FROM THE GROUP CONSISTING OF PIGMENT DISPERSING AGENTS, POTASSIUM TRIPOLYPHOSPHATE, SODIUM HEXAMETAPHOSPHATE AND SODIUM LAURYL SULFATE, AND THEN THE NEUTRALIZING THE DILUTED DISPERSED SLURRY TO PH OF 6.5 - 7.5, SEPARATING THE SPHERICAL PARTICLES FROM THE SOLVENT AND NON-SOLVENT AND DRYING THE PARTICLES.

2. Process according to claim 1 in which the amount of non-solvent used is from 1/4 to 4 parts by weight for each part of water.

3. Process according to claim 1 in which the non-solvent is an aromatic hydrocarbon selected from the group consisting of xylene, toluene and benzene.

4. Process according to claim 1 in which the emulsifying agent is present in the non-solvent in amount from 2% to 6% by weight of the non-solvent.