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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.





9 Pound-per-cubic-foot "Slow Cure" Semi-Rigid Foam



This foam polyurethane formulation is designed yield structural foam by either hand-mixing or machine casting method.  The pot-life of this material is set longer than ordinary rigid foam formulations to allow enough handling time in a hand-mixing operation.  Unlike common rigid foam formulation, the semi-rigid foam structure of MPP-M09D resists cracking and chipping from impact force by slight flexibility.  This combination of features makes MPP-M09A ideal for cat-in-place foam application, molding compound for short-run parts, and many other custom applications. 


The components are liquid at room temperature.  This can be batched manually by hand tools, and also be cast with a multi-component meter-mixing/dispensing machine.  The free-rise density of the foam is 9 pounds-per-cubic-foot, the cell structure is closed-cell. 


Component Properties

                                                                Prepolymer (A)                   Curing Agent (B)

Code Number:                                       MNB-013                             PPD-012                

Specific Gravity:                                   1.235                                       1.066

Equivalent Weight:                               134                                           116                      

%NCO                                                    31.3 %                                                                   


Mixing Ratio                                             (A)                                            (B)          

Volume Ratio:                                       1.000                                        1.000

Weight Ratio:                                        1.000                                        0.863

Stoichiometry NCO/OH:                      1.000                                         0.998

NCO Index                                             1.002                                        1.000


Processing Temperature:


Part-A                                                     Ambient

Part-B                                                     Ambient

Mold/Substrate                                      Ambient


* The ideal temperature for the mold and substrate is 100 - 110 F. However, if you are using plastic mold, this may not be necessary.  For all metal molds, the temperature needs to be between 100 to 110 F.   If a cold substrate must be used, you may yield a better result if the material is poured when the exothermic heat raised the temperature to above 90 F.


Cure Pattern:


Pot life (pour within)                             5 - 6 minute  (pour after 4-minute point if possible)

Demolding time                                    2 - 4 hours (thicker parts demold faster)

Complete Cure Cycle:                         2 days at room temperature

Foam Density:

Free Rise Density:                                8.2 8.5 pounds per cubic foot

Compressed density:                           9.0 pounds per cubic foot (recommended)



Recommended Processing:


We recommend testing this material small amounts to see how the material behaves, then develop your casting method accordingly.  When you do test batch, please be sure to operate in a well-ventilated area or large open area, wear rubber gloves, long sleeves, and protective eyeglasses to avoid skin/eye contact. Read the enclosed Material Safety Data Sheet for details on the safety and handling.


-          Agitate part-B component before dispensing out to ensure homogeneous blend within the part-B.  Part-B component is made of several different chemical constituents, which are not completely compatible to each other.  Use a bung mixer to agitate it for 20 to 30 minutes for 55-gallon drum package.  Use a paint mixer or spatula to agitate for a few minutes for 5-gallon pail and smaller packages. 


-          Pre-heat the mold and substrate to between 100 and 110 F in needed. 


-          Apply mold release into the mold when needed.  Do not use mold release with a high concentration of silicone as it destroys the foam surface.


-          Calculate the total inside volume of the mold (or the finished part volume) in cubic feet.  Divide it by the density (9 in this case). This will give you the weight of the component mixture at the free-rise density.  Use this total weight to calculate the weight ratio of the two components. 


-          Take the correct ratio of part-A and part-B into a mixing cup.  Mix well with a steel or plastic stir stick for at least 30 seconds.  Agitate vigorously and thoroughly.  Scrape the material off the side and bottom of the cup as you mix.   This material has a long pot-life for ease of use.  


-          Cast the mixture into the mold.  The mold should be between 100 and 110 F if using a metal mold.  The material may not cure properly if mold is too cold.   For a smaller batch size or the material needs to be cast on a cold substrate, do not pour until the blended mixture is starting to be slightly creamy and warm (this will happen at about the 4- to 5 minute point from the beginning of agitating part-A/B blend). 


-          Cure in the mold for 2 to 4 hours before demolding.  Please check the strength of the foam surface before demolding.  Larger parts can demold faster. 


-          The foam cures at room temperature gradually for about 2 to 3 days to yield the final physical properties that are OK to be used in a lord bearing application. 


Note: You may see non-foamed area at the bottom of the cured foam.  When the foam is cured in compression mold, or cast on cold substrate, the foam may create non-foam, solid areas.  If this is an issue, heating the mold or the substrate can alleviate.  Increasing the catalyst level may also reduce this tendency; however pot life will become shorter.  Holding the blended mixture in the cup until the material is creamy and warm may also help.



Compression Molding


Polyurethane foam needs to fill the mold space by the expansion pressure of the foam sending the foaming material to fill the mold.  The mold therefore needs to be close mold and has to have some capacity to retain the expansion pressure.  The simplest mold will be just an open-top box with a hard lid.  The lid then needs to be clamped hold the pressure. 


The air trapped in the mold could make a large void if it is not let out.  For this purpose, you need to have very small vents to let the trapped air escape from the mold.   You need to plan where in the mold the in-mold air is cornered by determining the position of the mold and cast point, and then drill small holes where you see the air traps. 


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 the heat.  Heat created from the chemical reaction (or exothermic heat) is required for foam to cure.  If mold is cold, this heat is absorbed and the foam does not cure properly.  The mold needs to be heat to 100 to 110 F in case of metal molds if metal mold.  If your mold is plastic or elastomeric mold, this may not be necessary as those materials retain heat better than metal molds. 


Compression rate is the rate of how much more material you would put in to create the pressure.  Typically, about 10 % compression should give enough pressure to distribute the foam within the mold.  Using higher rate makes the foam denser and stronger. 


If you have any questions, please feel free to call Northstar Polymers at 612-721-2911.  


Applications requiring fire-retardant grade


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 a 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.


Deflection Temperature


All semi-rigid foams soften as the temperature rises.  If load bearing capacity is required at an elevated temperature, test the structural integrity of the foam parts at the expected entire operating temperature range for the application.   




Handling Information for the Component Materials




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 65 and 80 F.


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; however most of the cases, keeping in an airtight container will be sufficient. Store it in a dry indoor storage at a room temperature between 65 and 80 F.




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. 


When using this material, 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, and if you expect the isocyanate content level in the work place atmosphere may become above the threshold regulated by OSHA or by other appropriate working place safety standard, we recommend, in addition to the above, installation of a proper hooded dynamic ventilation system and/or using an appropriate type of respirator (such as a full-face respirator equipped with OSHA approved HEPA filters for particulate and organic vapor) 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 and follow the other procedures of the Standard Industrial Hygiene Practices.  Please refer to the MSDS for each component for the detailed health information.




Northstar Polymers

3444 Dight Avenue South

Minneapolis, MN 55406 USA

Tel: (612)721-2911

Fax: (612) 721-1009

Home Page: 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