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Northstar Polymers, LLC

3444 Dight Avenue So.

Minneapolis, MN 55406

Tel: 612.721.2911

Fax: 612.721.1009

E-Mail: info@northstarpolymers.com

 

 

 

 

 

 

 

 

 

 

 

Northstar Polymers, LLC is a member of Polyurethane Manufacturers Association.

 

Copy right reserved by Northstar Polymers, LLC 2000 - 2007.  Northstar Polymer prohibits duplication of the contents of this web site for the purposes of public display and/or using on another web site without a written authorization by Northstar Polymers, LLC.

 

 

 

Easy Hand-Mixable/Pourable Flexible Foam

7 Pound-Per-Cubic-Foot Density

 

 

MPP-F07A


This foam formulation is designed to make molded flexible foam parts/sheets/dies/blocks by hand-mixing with very basic tools such as a cup and stir stick.  The components are low-viscosity stable liquid at room temperature.  These properties are ideal in small scale productions for custom foam applications such as custom seating, padding, cushioning, many others. 

 

The free-rise density of the foam is 6 to 7 pounds per cubic foot. The cell structure is partially open-cell, and may be made to open-cell structure by physically crushing soon after foam is made.  This is an MDI base water-blown polyether system, and it does not use auxiliary blowing agents

 

Examples for Applications:

 

  • Molded Upholstery Parts
  • Custom Seating, Padding, and Cushioning Parts
  • Custom Packaging of Impact/Vibration-Sensitive Items
  • Prototyping

 

 

Physical Properties of the Cured Foam

 

Property

Typical Value

Foam Density (Free Rise)

7.0 LBS/Cuft

Typical Compression Density

7.5 LBS/Cuft

Foam Consistency

Flexible

Apparent Surface Hardness

Shore OO 10 – 40

Foam Color

Off white*

 

*Note: The foam color is expected to turn to dark yellow from light, heat, and oxidation after exposure to ambient condition for a while.

 

Component Properties

                                                Prepolymer (Part-A)      Curing Agent (Part-B)

Code Number:                                    MPB-028                     PPC-026          

Specific Gravity:                                  1.108                           1.024  

Equivalent Weight:                            290                              268                 

            %NCO                                                 14.5 %                          n/a                             

 

 

Note: In the cold season, part-A component (MPB-028) may freeze during the shipping.  If the material arrives frozen, it must be thawed immediately.  To thaw MPB-028, the entire content needs to be heated to about 140 ˚F.   After the material is thawed to homogeneously smooth liquid consistency, the container top space needs to be purged with nitrogen gas and kept in an air tight container to store.  The storage temperature should be within the range of 72 to 90 ˚F.   Part-B component (PPC-026) is not likely to freeze in normal weather condition in winter.

 

 

Mixing Ratio                                       (A)                               (B)

                       

Volume Ratio:                                 100                             100

Weight Ratio:                         100                              93

Stoichiometry:                        1.00                             1.00

NCO Index                              1.00                             1.00

 

Processing Temperature:

 

Part-A                                      Room Temperature (70 – 85 ˚F)

Part-B                                      Room Temperature (70 – 85 ˚F)

Mold/Substrate                      Room Temperature (70 – 85 ˚F)

 

* Substrate can be at ambient temperature if it is made of plastic, resin, wood, or paper.  When casting on metal or other heat-absorbing materials, the substrate may need to be heated to 100 – 140 ˚F range.

 

Cure Pattern:

 

Pot life (pour within)                        60 - 80 seconds

Demolding time                                 1 to 2 hours

Complete Cure Cycle:                        48 hours at room temperature

 

Processing (manual hand-batch):

 

We recommend testing small amounts to see how the material behaves, then develop your processing method accordingly.  In here, the descriptions are for the manual hand-mixing process.   When you process/test, please be sure to operate in a well-ventilated area or large open area with a fan to move air; wear rubber gloves, long sleeves, and protective eyeglasses to avoid skin/eye contact.  Read the Material Safety Data Sheet for the details on safety and handling of each component.

 

Amount of foam enters into the mold is important to mold your foam parts at the right density.  Measure your in-mold volume in cubic inches.  Divide it by 1728 to obtain the volume in cubic foot.  Multiply by 7 to obtain the weight needed in the mold to get the 7 pounds per cubic foot density foam in pounds.  Use the mixing ratio supplied in this document to batch the foam resin.  The foam expands by approximately 9 to 10 times of the liquid volume.

 

About 1 to 2 hours after casting the foam resin, the foam should be solid enough to de-mold.  At this point, foam is expected to have a closed-cell structure.  This closed-cell foam may shrink badly after it cools down.  In order to avoid the shrinkage, the foam should be crushed down physically to force the internal cell structure to be open-cell.  At first, the foam feels like a balloon when you press.  You would hear popping sounds as you crush the foam.  You should crush all regions of the molded foam part so that the foam deflects equally throughout the part.    

 

 

Compression Molding

 

Foam needs to fill the mold space by put slightly larger amount of foam into the mold.  The expansion pressure of the foam sends the foam material to fill the mold to the expected shape.  The mold, therefore, needs to be a closed mold and has to have a capacity to retain the internal pressure.  A simplest compression mold will be an open-top box with a lid.  The lid needs to be clamped to hold the pressure. 

 

The air trapped in the mold could make large voids if it is not vented.  For this purpose, you need to have very small holes to let the trapped air escape from the mold.  Determine the mold position so that trap air is pushed toward a corner or sections where the vent holes are.  Small amounts of the foam may squeeze out from the vent holes, which you can machine off after the part is cured.

 

The mold material can be metal, plastic, or elastomeric material.  Mold surface needs to be slick as foam could stick to any porous surface.  Metal molds tend to absorb heat.  The heat created from urethane reaction is required for foam to cure properly.  If mold is cold, this heat is absorbed and the foam does not cure properly.  The mold needs to be heat to 100 to 140 ºF range in case of using metal molds.  If your mold is made of a plastic or elastomeric material, such as silicone rubber, epoxy, and urethane, this may not be necessary.  Please test and determine the optimal temperature for your mold.  Higher mold temperature increases the shrinkage rate.  For tight shrinkage variation, controlling temperature parameters is very important. 

 

The “compression rate” describes the additional amount of material you would put into the closed mold to create the internal pressure so that the foam fills the entire inside space of the mold.  Typically, about 5 to10 % compression should give enough pressure to distribute the foam within the mold.  Using higher rate makes the foam denser and stronger.  However, it will increase the chance of closed-cell/shrinkage problem described below. 

 

 

 

 

Other Information

 

Applications that requires fire-retardant property:

 

This foam is not fire-retardant foam, and it is not recommended for applications, which require or should be using fire-retardant grade materials.  The applications such as automotive interior, building material, and components for some electronic parts often require fire-retardant grade materials by law. It is the user's responsibility to conform to the applicable regulations.  We also do not recommend this foam to be used to the applications in which the foam can be exposed to high temperature or being near an ignition source.

 

By adding fire retardant additives, this foam may be modified to fire-retardant grade foam.  The user must test the foam modified with the fire retardant additives for the fire-retardant property and the conformance to the applicable regulations.

 

Storage:

 

Part-A component (prepolymer) contains isocyanate component, which is very much sensitive to moisture.  If it is left in air, part-A will react with atmospheric moisture and will be ruined.  This reaction is non-reversible.  Soon after opening a can and dispensing the content, nitrogen gas or argon gas needs to be injected to the can to blanket the material.  Silica gel or calcium chloride desiccant filter should be installed to 55 gallon drum-vent for your drum feeding system.  The storage temperature should be at a room temperature between 72 and 90 ºF.

 

Part-B component is hygroscopic.  If the material is exposed to ambient air, it may absorb moisture. Moisture contaminated part-B material may become source of degradation or excessive bubbles in the product. Avoid exposure of the material to air.  Purging the empty space in the container with nitrogen gas or negative-40-degree-due-point dry air is also recommended to prevent moisture contamination of part-B as well. The storage temperature should be at a room temperature between 65 and 90 ºF.

 

Safety:

 

The component materials are industrial-grade chemicals.  Please keep them in a secure place and prevent access from any unauthorized individual.  The personnel who handle these materials need to read the Material Safety Data Sheet (MSDS) for detail information on safety and handling of the material.  The MSDS for each component is sent with the shipment of the material. 

 

Whenever using this material, please be sure to operate in a wide-open area with good air movement or in a well-ventilated area. Wear rubber gloves, long sleeves, and protective eyeglasses to prevent skin/eye contact of the material.  When your operation involves heating or spraying of the material, we recommend, in addition to the above, installation of a proper ventilation system and using a half-face respirator recommended for the use to prevent inhalation of the fume.  

 

Direct contact of polyurethane raw materials to skin/eye, as well as ingestion may lead to health problems.  No eating or smoking should be permitted at the working area.  The operator should wash hands well with soap and water after handling the materials.  Please refer to the MSDS for each component for the detailed health information.

 

 

 

 

For any questions, please contact Northstar Polymers.

 

Tel:         612-721-2911.

Fax:         612-721-1009

Web Site:    http://www.northstarpolymers.com

E-Mail:      info@northstarpolymers.com

 

Notice: All of the statements, recommendations, suggestions, and data concerning the subject material are based on our laboratory results, and although we believe the same to be reliable, we expressly do not represent, warrant, or guarantee the accuracy, completeness, or reliability of same, or the material or the results to be obtained from the use thereof, neither do we warrant that any such use, either alone or in combination with other materials, shall be free of the rightful claim of any third party by way of INFRINGEMENT or the like, and NORTHSTAR POLYMERS DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, OF MERCHANTABILITY and FITNESS FOR A PARTICULAR PURPOSE.              

 

 


 

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Northstar Polymers, LLC

3444 Dight Avenue South

Minneapolis, MN 55406

Tel: 612.721.2911

E-Mail: info@northstarpolymers.com

 

Notice: All of the statements, recommendations, suggestions, and data concerning the subject material are based on our laboratory results, and although we believe the same to be reliable, we expressly do not represent, warrant, or guarantee the accuracy, completeness, or reliability of same, or the material or the results to be obtained from the use thereof, neither do we warrant that any such use, either alone or in combination with other materials, shall be free of the rightful claim of any third party by way of INFRINGEMENT or the like, and NORTHSTAR POLYMERS DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, OF MERCHANTABILITY and FITNESS FOR A PARTICULAR PURPOSE.