Foamed material and a method of making a foamed material

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(12) United States Patent

Hunt et al.

(io) Patent No.: (45) Date of Patent:

US 7,582,335 B2 Sep. 1, 2009

(54) FOAMED MATERIAL AND A METHOD OF MAKING A FOAMED MATERIAL

(75) Inventors: Joanne S. Hunt, Aylesbury (GB); Julie Baker, Leavesden (GB); Alan R. Pitt,

Sandridge (GB)

(73) Assignee: Eastman Kodak Company, Rochester, NY (US)

( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 422 days.

(21) Appl.No.: 10/551,916

(22) PCT Filed: Apr. 2, 2004

(86) PCT No.: PCT/GB2004/001470

§ 371 (c)(1),

(2), (4) Date: Oct. 5, 2005

(87) PCT Pub. No.: WO2004/090027 PCT Pub. Date: Oct. 21, 2004

(65) Prior Publication Data

US 2006/0270745 Al Nov. 30, 2006

(30) Foreign Application Priority Data

Apr. 5, 2003 (GB) 0307963.9

(58) Field of Classification Search 521/50.5,

521/65, 66, 72; 427/508, 553, 557, 466 See application file for complete search history.

(56) References Cited

U.S. PATENT DOCUMENTS

4,296,210 A 10/1981 Zimmermann et al.

4,808,637 A * 2/1989 Boardman et al 521/50.5

5,128,313 A 7/1992 Aono

5,338,766 A * 8/1994 Phanetal 521/63

5,382,285 A 1/1995 Morrison

6,261,679 Bl* 7/2001 Chenetal 428/317.9

2005/0112302 Al * 5/2005 Laneyetal 428/32.31

2006/0015083 Al* 1/2006 Munroetal 604/367

2007/0054070 Al * 3/2007 Laneyetal 428/32.34

FOREIGN PATENT DOCUMENTS WO 02/26872 Al 4/2002

* cited by examiner

Primary Examiner—Susan W Berman

(74) Attorney, Agent, or Firm—Chris P. Konkol; Arthur E.

Kluegel

The invention provides a method of making a material, said method comprising generating a foamedhydrophilic polymer solution, especially of a gelatin or derivative thereof, and treating said foamed hydrophilic polymer solution with sufficient energy and for a sufficiently short time that a polymer foam having an open-cell structure is formed. The invention also provides a material comprising a support and an ink receiving layer supported on the support, the ink receiving layer comprising porous hydrophilic polymer, especially gelatin, and is formed by coating a solution of foamed hydrophilic polymer, especially gelatin, onto a support substrate and drying the coated substrate for a time period selected to be short enough such that an open-cell foam is formed.

17 Claims, 2 Drawing Sheets

1

FOAMED MATERIAL AND A METHOD OF
MAKING A FOAMED MATERIAL

FIELD OF THE INVENTION

5

The present invention relates to a method of making a foamed material. In particular the invention relates to a method of making a foamed material suitable for use as, amongst other things, an ink-jet receiver. The invention also relates to a material made using the method. 10

BACKGROUND OF THE INVENTION

To be suitable for use as an ink-jet receiver, a material is preferably quick to absorb applied ink and also, once dry, 15 printed images are preferably stable when subjected to light and ozone. Ink-jet media having a porous layer are typically formed of inorganic materials with a polymeric binder. When ink is applied to the medium it is absorbed quickly into the porous layer by capillary action. However, the open nature of 20 the layer can contribute to a lack of stability of printed images when subjected to light and ozone. Ink-jet media having a non-porous layer are typically formed by the coating of one or more polymeric layers onto a support. When ink is applied to such media, the polymeric layers swell and absorb the applied 25 ink. However, due to limitations of the swelling mechanism, this type of media is slow to absorb the ink, but once dry, printed images are often stable when subjected to light and ozone.

Polymer foams have been developed that are suitable for 30 use as inkjet receivers. The materials, as disclosed for example in our co-pending European Patent Application Number 03015858.8, can be both quick to absorb applied ink and also provide images that are stable to light and ozone once dry. 35

Traditionally, polymer foams are manufactured using mostly hydrophobic thermoplastic materials such as polyurethane, PVC and polyethylene. Initially a gas filled polymer is created using a known foaming method, the gas-filled polymer then being coated onto a support substrate. 40

Typical-foaming methods include:

1. Thermal decomposition of chemical blowing agents, generating N2 or C02, by application of heat or as a result of the exothermic heat of reaction during poly- ^ merisation.

2. Mechanical whipping of gases into a polymer melt, which hardens either by catalytic action or heat, trapping gas bubbles in a matrix.

3. The use of low boiling point liquids which boil at low 5Q temperatures thereby creating gas.

4. Expansion of a gas dissolved in a polymer upon reduction of pressure in the system.

5. Incorporation of microspheres into a polymer mass, the microspheres consisting of gas filled polymer that 55 expands upon heating.

After obtaining the gas filled polymer by one or more of the methods above, the material is then formed, typically, using one of three common manufacturing processes:

1. Compression moulding go

2. Reaction injection moulding or

3. Extrusion of the foam.

The temperatures involved in these processes can be very high, e.g. in excess of 150° C, as the polymers used are in their molten state. The most common processing method used 65 in creating polymer foam films is extrusion. This is a threestage operation consisting of forming a polymer solution with

2

gas dissolved in it, by injection of N2 or C02, or by the use of blowing agent, to create a single phase solution. Nucleation sites are then formed, as a result of a rapid pressure drop to create large numbers of uniform sites. Cell growth then takes place by means of diffusion of the gas to form bubbles. Control of the processing conditions provides the pressure and temperature changes necessary to control cell growth.

US-A-2001/0021726 (James F. Brown) discloses porous surface compositions and methods of retaining biological samples on the surface. The method relies on the use of curable polymers. U.S. Pat. No. 3,794,548 (C. Wirth et al) discloses the use of polyurethane as a porous polymer film. Polymer is heated causing volatilisation of solvents within the polymer resulting in a porous coating. U.S. Pat. No. 6,228, 476 (Bogrett et al) relates to a foam insulation sheet made using curable polymers.

Problem to Be Solved By the Invention

A problem with conventional methods of making foamed materials suitable for use as ink-jet receivers is that the methods used to create polymer foams rely on high processing temperatures. This is undesirable as it is expensive in terms of energy requirements. Furthermore it is desirable to have a manufacturing process that does not require high temperatures, on grounds of safety.

A method of making a material is desired without the use of traditional foam manufacturing systems. A material is also required that can be made using methods that do not rely on traditional foam manufacturing systems.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a method of making a material, said method comprising generating a foamed hydrophilic polymer solution and treating said foamed hydrophilic polymer solution with sufficient energy and for a sufficiently short time that a polymer foam having an open-cell structure is formed.

In a second aspect of the invention, there is provided a material obtainable by the above method.

In a third aspect of the invention, there is provided an ink-jet receiver comprising a material as defined above.

In a fourth aspect of the invention, there is provided an ink-jet receiver, comprising a support and an ink-receiving layer on said support, said ink-receiving layer comprising a hydrophilic polymer foam material obtainable by the above method.

In a fifth aspect of the invention, there is provided the use of microwave radiation to form a polymeric foam material having an open-cell structure from a foamed hydrophilic polymer solution.

Advantageous Effect of the Invention

The invention provides a method of making a material using a solution of hydrophilic polymer having bubbles created therein. In contrast to traditional polymer foams, which are manufactured using mostly hydrophobic thermoplastic materials such as polyurethane, PVC and polyethylene, lower processing temperatures can be used. Hydrophobic thermoplastic materials such as polyurethane, PVC and polyethylene require high processing temperatures since the polymers are in their molten state. Temperatures higher than 150° C. are commonplace.

The present invention provides a simple and robust method for the manufacture of a polymer foam material, suitable, for