§
Luxuse
Patent Intelligence
Sign In
← Back to Patent Explorer
EP0349240A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Water-absorbent resin and production process

Assignee: Nippon Shokubai Co Ltd
•
Filing: 1989-06-26
•
Granted: —
•
Expires: 2009-06-26
📄 Original PDF 🌐 Google Patents 🔄 Sync Now

Abstract

Abstract This invention relates to a water-absorbent resin of new, novel type obtained from polymerization of a water-soluble ethylenically unsaturated monomer followed by surface treatment and, in addition, a process for producing this resin. The water-absorbent resin in this invention has average particle diameter in a specially defined range and a narrow range of particle distribution. And furthermore, since the particle surface is treated with crosslinking, a balance is very good among water absorption properties, for example, between water absorption capacity and water absorption rate, and between gel strength and suction force. This water-absorbent resin is takable a angle-lacking, non-sphere shape and in a case of this type of shape, it is superior in such handling properties as falling off from an basis material being hard. Since the production process in the present invention comprises crosslinking treatment for the particle surface of a specially defined water-absorption polymer, the crosslinking is performed with good efficiency and, a water-absorption resin being superior in a balance among water absorption properties is obtainable with an economic advantage. This specially defined water-absorption polymer particle is obtained by polymerizing a water-soluble ethylenically unsaturated monomer in a process of reverse-phase suspension polymerization, In the production process of this invention, since the aqueous monomer solution is chosen from those in a specially defined viscosity range and then, dispersed and suspended by using a specially defined dispersing agent, a specially defined water-absorbent resin is easily obtainable wherein, not only the average particle diameter is controlled by adjusting the viscosity of an aqueous monomer solution, but also the particle diameter distribution resulted is narrow. In this production process, the particle shape can be changed by changing up and down the viscocity of an aqueous solution of monomer in the above-described specially defined range. The water-absorbent resin in this invention, because it has the above-described properties, is preferably used for sanitary materials and the like.

Inventors

  • 👤 Kazumasa Kimura
  • 👤 Kinya Nagasuna
  • 👤 Takashi Namba
  • 👤 Kenji Kadonaga
  • 👤 Koji Miyake
  • 👤 Tadao Shimomura

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-24 16:20
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/12; C08F; C08F2/00; C08F2/32; C08F8/00; C08J2300/00; C08J2300/14

Claims Analysis

Total Claims: 17
Claim 1
Independent Claim 36 words
Water-absorbent resins having average particle diameter of 100 - 600 nm, showing particle diameter distribution of 0.35 or less in a value of logarithmic standard deviation, ar , and being treated with crosslinking on particle surface.
Claim 2
Dependent Claim 36 words
Water-absorbent resins having average particle diameter of 100 - 600 nm, showing particle diameter distribution of 0.35 or less in a value of logarithmic standard deviation, ar , and being treated with crosslinking on particle surface.
Claim 3
Dependent Claim 28 words
Water-absorbent resins of non-sphere, angle-lacking shape wherein a ratio between length and breadth being in a range of 1.5- 20, and whose particle surface being treated with crosslinking.
Claim 4
Dependent Claim 28 words
Water-absorbent resins of non-sphere, angle-lacking shape wherein a ratio between length and breadth being in a range of 1.5- 20, and whose particle surface being treated with crosslinking.
Claim 5
Dependent Claim 35 words
Water-absorbent resins as claimed in claim 2, wherein the length of particles being in a range of 100 - 10,000 µm and the breadth of particles being in a range of 10 - 2,000 µm.
Claim 6
Dependent Claim 45 words
A process for producing water-absorbent resins wherein the surface of a polymer powder having an average particle diameter of 100 - 600 µm and a particle diameter distribution of 0.35 or less in a value of a logarithmic standard deviation, σζ, being treated with crossliking.
Claim 7
Dependent Claim 45 words
A process for producing water-absorbent resins wherein the surface of a polymer powder having an average particle diameter of 100 - 600 µm and a particle diameter distribution of 0.35 or less in a value of a logarithmic standard deviation, σζ, being treated with crossliking.
Claim 8
Dependent Claim 36 words
A process for producing water-absorbent resins wherein the surface of a polymer powder having a ratio of 1.5 - 20 between an average particle length and an average particle breadth and showing an angle-lacking, non-sphere shape.
Claim 9
Dependent Claim 36 words
A process for producing water-absorbent resins wherein the surface of a polymer powder having a ratio of 1.5 - 20 between an average particle length and an average particle breadth and showing an angle-lacking, non-sphere shape.
Claim 10
Dependent Claim 28 words
A process for producing water-absorbent resins as claimed in claims 4 or 5, wherein the water content of a polymer powder is less than 10 weight % .
Claim 11
Dependent Claim 84 words
A process for producing water-absorbent resins as claimed in claims 4, 5, or 6, wherein an aqueous solution of water-soluble ethylenically unsaturated monomer having a viscosity of 15 cps or more, determined by a Brookfield rotational viscometer ( 25 ° C, 0.6 rpm ), with using a sucrose fatty acid ester and/or a polyglycerol fatty acid ester as a dispersing agent, being dispersed and suspended in a polymerization-inert hydrophobic organic solvent and polymerized by an initiator for radical polymerization to obtain a polymer powder.
Claim 12
Dependent Claim 32 words
A process for producing water-absorbent resins as claimed in claim 7, wherein viscosity of an aqueous solution of water-soluble ethylenically unsaturated monomer being adjusted in a range of 15 - 5,000 cps.
Claim 13
Dependent Claim 41 words
A process for producing water-absorbent resins as claimed in claim 7, wherein viscosity of an aqueous solution of water-soluble ethylenically unsaturated monomer being adjusted in a range of 5,000 - 1,000,000 cps and a sucrose fatty acid ester being only used.
Claim 14
Dependent Claim 46 words
A process for producing water-absorbent resins as claimed in claims 4, 5, 6, 7, 8 or 9, wherein, when being treated with crosslinking, an agent having in the molecule two or more of a group reactive for a functional group of the polymer powder is used.
Claim 15
Dependent Claim 35 words
A process for producing water-absorbent resins as claimed in claim 10, wherein the crosslinking agent is used in form of a treatment solution prepared by mixing this agent with water and a hydrophilic organic solvent.
Claim 16
Dependent Claim 50 words
A process for producing water-absorbent resins as claimed in claim 11, wherein the composition proportions of a crosslinking agent, water, and a hydrophilic organic solvent are adjusted as, against the polymer powder, 0.005 - 20 weight %, 0.1 - 5 weight %, and 0.01 - 6 weight % , respectively.
Claim 17
Dependent Claim 42 words
A process for producing water-absorbent resins as claimed in claim 11 or 12, wherein a polymer powder is mixed with a treatment solution, then warmed at 40 - 250 ° C and the surface of above-described polymer powder is treated with crossliking.

References Cited (Backward Citations)

No citation records indexed.

USPTO Annuity & Maintenance Windows

Maintenance schedule is calculated for granted US utility patents.

Assigned Categories & Tags

No categories assigned to this patent yet.

Assign Category Tag