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Northstar Polymers, LLC

3444 Dight Avenue So.

Minneapolis, MN 55406

Tel: 612.721.2911

Fax: 612.721.1009





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.


Technical Data Sheet



Easy-To-Use Mold-Making Resin

 Prepolymer (Part-A): MPC-038        Curative (Part-B): PAA-071


 MPA-A30B is one of our room-temperature-cure liquid castable polyurethane systems.  This ether-base polyurethane system is used in applications such as mold-making, prototyping, production of cast parts, potting, tool-making, and many other applications.  MPA-A30B is designed for an easy operation for industrial applications without special casting or heating equipment.  The mixing ratio between part-A (MPC-038) and part-B (PAA-071) is 1:2 by volume.  The material is specially formulated to be less moisture sensitive for relatively uncontrolled processing environments. Its low viscosity also makes it easy to achieve replicating the details of the mold/original with a fine resolution.  Urethane elastomer parts made of this system exhibit:


q      Fine resolution of mold details

q      Good resiliency and elongation for easy demolding of parts

q      Good cut/tear resistance for its class

q      Good performance in wet environments


 The suitable applications of MPA-A30B include stamps/patterns and concrete molds designed to transfer a decorative image to wet surfaces.  Its property of small shrinkage rate provides users with a tight dimensional stability when a replication is made.


Physical/Mechanical Properties


Typical Value

Durometer Hardness


A 30 35

Tensile Strength


478 psi

Ultimate Elongation


435 %

Tear Resistance:  Die C


148 pli

Tear Resistance: Split


52 pli

Natural Color of Solid


Semi-translucent amber

 Mixing Ratio






Product Code:



Volume Ratio:



Weight Ratio:










 Curing Pattern:

Pot life:                                                   17 20 minutes

Demolding time:                                  8 hours

Complete Cure Cycle:                        3 4 days at room temperature

Note: Larger batch size and higher processing temperature speeds up the curing pattern.

 Processing Conditions


Component Temperature:

Room Temperature (65 -90 F)

Mold Temperature:

Room Temperature*

Post Cure Temperature:

Room Temperature


*Note: Mold temperature can be elevated for faster demolding time. Mold can be in the range of 70 F to 160 F

 Component Properties: 







General Description

MDI Prepolymer

General Description

Curative (Polyol Blend)


Specific Gravity


Specific Gravity



Viscosity at 77 F

1200 1400 cps

Viscosity at 77 F

 800 - 1200 cps




Equivalent Weight



Amine Equivalents


Appearance at 72 F

Amber Color Liquid with haze

Appearance at 72 F

Amber Color Liquid












Recommended Procedure (for the mold-making application) 


          Store the material at room temperature until the actual temperature of the components are within the range of 70 90 F.  The work place humidity is recommended to be less than 50%.  Use of a dehumidifier is recommended if your work place humidity is above 50%.


          Wear rubber gloves, long sleeves, and protective eyeglasses to avoid skin/eye contact of the material.  (Refer to the safety and handling column at the end of the document for the details.)


          Models made of concrete, wood, plasters, or any porous materials need to be sealed with a sealer such as acrylic or shellac sealer.  Apply mold release after the sealer is completely dried.  Solid silicone or solvent based release agent is recommended.  Do not use water base release agent.  Non-porous models such as solid plastic or other polymers do not need to be sealed, but still requires mold release.


          Re-blend part-B component before dispensing out from the original container.  Part-B component contains a small amount of powder material, which expected to separate and settle at the bottom of the container during the storage.  Part-B material needs to be agitated to re-blend all the constituents within.  Use a clean/dry spatula or a hand-held powered mixer at low speed to agitate.  Try not to enclose air bubbles while agitating. 


          Use a clean/dry mixing container such as a plastic pail, and pour the correct ratio of part-A and part-B, according the ratio information on this document, into the mixing container.  Use a dry/clean stainless steel spatula or a hand-held powered mixer at a medium speed to agitate the part-A/B mixture for 2 to 3 minutes depending on the batch size.  Mix fairly vigorously and thoroughly without whipping or enclosing too much air.  Scrape the side and bottom of the container with a spatula as you agitate to ensure the homogenous mix.


          Pour the blended material into the mold or frame with original/model piece.  For finer details, you may need to pour slowly to cover the surface with find detailed pattern first, and then fill the rest.  For undercuts, fill to just above the under cut and tilt the mold/frame to let the air escape from the under cut sections then fill the rest.  Material increases its viscosity gradually.  For better resolution and less air traps, finish pouring before the material gets thick.


          Let the material cure at room temperature until it is strong enough to demold or until the demolding time specified in this document.  The mold material cures to complete cure in about 3 to 4 days at room temperature.  After demolding, you may post cure the material at 150 180 F for 6 to 8 hours to finish off curing faster. 


          The finished mold can be put into service after it is cured completely.  The longevity of the mold depends on how it is used.  If you need to stretch the mold very far, you may need to use softer material to avoid tear.  If it cuts easily in your operation, harder materials have better cut resistance.  Choose the hardness of urethane mold-making formulas accordingly.  Exposure to sunlight, high heat, acid, solvents, or other strong chemicals can reduce the longevity of your urethane molds.   It is recommended that the urethane molds are stored indoor to avoid direct sunlight and widely varying environments.  Avoid extreme high temperature, as well as use of strong acid and solvents on the urethane mold, and limit the time the urethane mold is immersed in water for longer life of your molds.   


Handling Information for the Component Materials



Part-A: 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 negative-40-degree-due-point dry air 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 90 F.


 Lower temperature (Below 65 F) can cause this part-A to freeze.  During the cold seasons, this material may be exposed to a very low temperature while shipping.  The state of frozen material can be either solid, waxy, gelled, or has very high viscosity with creamy dark yellow color. If freezing is suspected, you need to thaw the material before using.  You can use drum heater, industrial oven, or lab oven to heat it to 150 160 F or until it is thawed.  Thawed material should look translucent dark amber color with smooth liquid consistency.

Part-B: When part-B is exposed to ambient air, it can absorb moisture. Moisture contaminated part-B material may become source of degradation or excessive bubbles in the product. Although this material is formulated with less moisture sensitive materials, it is best to avoid exposure of the material to moisture in the 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. 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 90 F.

(The moisture contamination of part-B material is reversible.  By heating material to 160 - 180 F and vacuuming it at about 29" Hg negative pressure for several hours will reduce the moisture level.)



The component materials are industrial-grade chemicals.  Please keep them in a secure place and prevent access from any unauthorized individuals.  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, we recommend, in addition to the above, installation of a proper ventilation system and/or using an appropriate quality of respirator 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.


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.