Ontario Specialty Coatings Corporation

 

THE LEADER IN DIGITAL IMAGING COATING TECHNOLOGY

 

 


 

Home
Up

Ink Jet Coating Binders

 

Types Generally Used:        

Polyvinyl Alcohol

Photographic Gelatins

Acrylic Latex

Styrene-Butadiene Latex

Cationic Corn Starch

Ethylated Corn Starch

 

Typical Binder Levels:

Polyvinyl Alcohol (PVOH): 5 - 35 parts on 100 parts pigment, depending upon degree of hydrolysis, the type of pigments used, the type and level of co-binders, and the coating application method. Polyvinyl Alcohol tends to have a dilatent rheology which increases with the level of hydrolysis.

Properties:       

pH of a 4% aqueous solution: 4.0 - 7.5

Degree of hydrolysis: 88 - 99+%

Brookfield Viscosity of a 4% aqueous solution at 20oC: 3.5 - 72 cps.

Cost: High

 

Photographic Gelatins: Generally 20 - 50 parts in clear coatings (no opacifying pigments). Gelatins are used both as a binder and an ink vehicle absorption medium. Gelatins are usually extremely hydrophilic, absorbing large amounts of water and other polar solvents. They can be insolubilized to varying degrees, producing very water resistant coatings.

Properties: Variable, depending upon the specific gelatin selected and how it is prepared in solution. Cost is high.

 

Acrylic Latex: 5 - 100 parts on 100 parts of pigment. Latex is generally used as a co-binder with polyvinyl alcohol to lower costs, or as the primary binder. It imparts thixotropy to the coating, improving performance in the application process. Acrylic latex resists yellowing due to ultraviolet light and is sometimes used in place of styrene-butadiene latex for this reason.

Properties:      

pH: 6.5 - 8.5

Solids: 40 - 55%

Density: 8.5 - 9.0 lbs./gallon

Brookfield Viscosity: (No. 2 spindle, 60 rpm), 50 - 150 cps.

Cost: Moderate to High.

 

Styrene-Butadiene Latex: 2 - 20 parts on 100 parts of pigment. Latex is generally used as a co-binder with polyvinyl alcohol to lower costs, or as the primary binder. It imparts thixotropy to the coating, improving performance in the application process. Styrene-Butadiene latex is a lower cost alternative to acrylic latex, but is generally sensitive to yellowing under ultraviolet light. However, some styrene-butadiene polymers are modified to offer resistance to ultraviolet light.

Properties:     

pH: 6.5 - 8.5

Solids: 45 - 50%

Density: 8.5 - 9.0 lbs./gallon

Brookfield Viscosity: (No. 2 spindle, 60 rpm), 50 - 150 cps.

Cost: Moderate

 

Corn Starch: 10 - 100 parts on 100 parts of pigment. Corn starch is the least expensive and lowest binding strength/binding efficiency coating binder. Corn starch comes in several varieties and the cost and binding strength will vary depending upon the type used. Ethylated corn starches are basic, general purpose binders. They are relatively inexpensive and easy to work with. Cationic corn starches are more highly refined and are stronger, more efficient binders, but are also more expensive. Starch significantly reduces coating costs over other binders such as polyvinyl alcohol and latexes and also imparts thixotropy to the coating, improving the performance of the coating in the application process.

Properties:          

pH of a 20% aqueous solution: 5.5 - 7.5

Cooked solids: 15 - 35%, depending upon molecular weight.

Brookfield Viscosity: Will vary greatly depending upon the type of starch, the molecular weight, and the starch solution solids.

Cost: Low

 

Suppliers:

Polyvinyl Alcohol:            

Celanese

DuPont

 

Photographic Gelatins:       

Kind and Knox Gelatin

Eastman Gelatin Corporation

Atlantic Gelatin

 

Acrylic Latex:                    

B.F. Goodrich

Rohm & Haas

Reichold

B.A.S.F.

 

Corn Starches:                   

National Starch

Penford Products

Staley