Technical Data
Sheet
SIGMA CURE 7621 PART II ISOCYANATE RESIN
Premium Performance Urethane Cold Box Part 2 Resin Designed
for Improved Core Release
Performance Features
Sigma Cure 7621 Isocyanate Part 2 Resin was specifically developed for use with
Sigma Cure Phenolic Urethane Part 1 Resins, and offers a number of distinct
features and advantages when compared to the benchmark Sigma Cure 7500
resin, and older Acme Flow series Part 2 resins. The features include:
•
•
•
•
•
Higher Tensile Strengths
Extended Mixed Sand Bench Life
Superior Hot Strength
Better Shelf Life of Cores
Low VOC’s
Product Description
Sigma Cure 7621 is a polymeric MDI-type isocyanate resin that is used in
conjunction with a phenolic resin, such as Sigma Cure 7121, for ferrous cold box
applications. Typically, the Part 1 and Part 2 resin components are mixed with a
suitable new sand, normally a dry silica sand or lake sand, or a reclaimed sand, in
ratios ranging from 50/50 to 60/40, and at a total resin level in the range 0.8 to
2.0%, based on the weight of the sand. The resulting sand mix is then blown into
a core box and is subsequently crosslinked by the passage of a vaporized tertiary
amine catalyst such as triethylamine or dimethylethylamine to produce a urethane
bond.
SELLER MAKES NO WARRANTY, EXPRESS OR IMPLIED CONCERNING THE PRODUCT OR THE MERCHANTABILITY
OR FITNESS THEREOF FOR ANY PURPOSE OR CONCERNING THE ACCURACY OF ANY NFORMATION BY SELLER,
except that the product shall conform to contracted specifications, and that the product does not infringe any valid United States patent.
The information provided herein was believed by Seller to be accurate at the time of preparation or prepared from sources believed to be
reliable but it is the responsibility of the user to investigate and understand other pertinent sources of information to comply with all laws
and procedures applicable to the safe handling and use of product and to determine the suitability of the product for its intended use.
Buyers exclusive remedy shall be for damages and no claim of any kind, whether to product delivered or for non-delivery of product and
whether based on contract, breach of warranty, negligence or otherwise shall be greater in amount than the purchase price of the quantity
of product in respect of which damages are claimed. In no event shall Seller be liable for incidental or consequential damages, whether
Buyer’s claim is based on contract, breach of warranty, negligence or otherwise.
Typical Properties - Sigma Cure 7621
Flash Point, o F, TCC
>210
60
Viscosity, cps
1.605
Refractive Index
9.7
Density, pounds/gallon
Tensile Strength Development
Tensile strength development occurs almost instantaneously before the core is
ejected from the core box. Initial tensile strength at ejection typically ranges from
60 to 80% of the ultimate tensile strength at 24 hours. The value is adversely
affected by clay and other alkaline contaminants, and by moisture in the sand or
high dew points in the compressed purge air. Tensile strength values will vary as
a function of the degree of angularity and the AFS grain fineness number of the
sand that is selected. The graphs below illustrate the tensile strength development
and bench life performance of Sigma Cure 7621, when used with Sigma Cure
7121 Part 1 Phenolic Resin, compared to Sigma Cure 7110 /7611 on a typical
silica sand. Total resin content was 1.2%, based on sand, at a 55/45 ratio of Part
1/Part 2. Actual results may vary due to the many variables known to affect
binder performance, e.g. sand quality, sand temperature.
Tensile Strength Development
T E N S IL E B U IL D C O M P A R IS O N
1 .2 % B in d er (B .O .S ); 5 5 /4 5 P a rt 1 /P a r t 2 ; 5 3 0 W e d ro n S a n d
350
TENSILE STRENGTH (psi)
300
250
200
150
100
7 1 2 1 /7 6 2 1
7 1 1 0 /7 6 1 1
50
0
1 M in u te
1 H our
24 H our
24 H our; 100% R H
(D e s.)
AGE OF CORE
HA International LLC
“The Best Total Solution”
630 Oakmont Lane
Westmont, IL 60559
Telephone (630) 575-5700 Fax (630) 575-5800
Bench Life
B E N C H L IF E C O M P A R IS O N
1 .3 % B in d e r ( B .O .S ) ; 5 5 /4 5 P a r t 1 /P a r t 2 ; 5 3 0 W e d r o n S a n d
250
TENSILE STRENGTH (psi)
200
150
7 1 2 1 /7 6 2 1
7 1 1 0 /7 6 1 1
100
50
0
0
1
2
3
A G E O F M IX
Storage Guidelines
Recommended storage temperature is between 60 - 90 °F. At lower temperatures,
viscosity will increase, making pumping and mixing more difficult. At high
temperatures, solvent loss can occur. Drum storage should be in a dry area, out of
direct sunlight. Partially used drums should be tightly closed to prevent
contamination, primarily from water, which can react to form solids and carbon
dioxide gas. Part 2 resins are reactive with moisture and humidity. Protect drums
with desiccant if rate of use is slow. Protect bulk storage tank with dry nitrogen
or dry air (-40 °F or less dew point).
Safe Handling
Chemically resistant gloves and eye protection should be used when handling or
using chemical binders. Material Safety Data Sheets are available for all
products. Drum labels also contain handling information. This material will react
with the Part 1 resin, without catalyst, in an exothermic reaction, to give a solid
polymer. Do not mix Part 1 and Part 2 except on sand during use.
Technical Service
Proper selection of a binder system that meets your specific needs is key to
achieving maximum performance benefits. HA International, LLC provides indepth technical assistance and a wide range of urethane cold box binder systems.
Both our in-house and field experts are available to assist you in your most
challenging foundry applications. Please contact your HA International, LLC
representative so that we may assist you in putting together a binder system and
foundry team that will help you achieve your goals.
June 2001
HA International LLC
“The Best Total Solution”
630 Oakmont Lane
Westmont, IL 60559
Telephone (630) 575-5700 Fax (630) 575-5800