HQ 083986
April 7 1989
CLA 2 CO:R:C:G 083986 JGH 835339
Stephen S. Spraitzer, Esq.
George R. Tuttle
Three Embarcadero Center, Suite 1100
San Francisco, California 9411
RE: Classification of Silane Coupling Agents
Dear Mr. Spraitzer:
This is in reference to your request for a classification ruling under the Harmonized Tariff Schedule of the United States (HTSUS) for two silane coupling agents, products of
Japan.
FACTS:
KBE 903 /(3 triethoxysilyl) 1 propanamine/ and KMB 403 [trimethoxy(3 oxiranylmethoxy] propyl silane/ are described as silane coupling agents to be used, among other things, for the performance improvement of fiber reinforced plastics by direct
admixture to synthetic resins, improvement in paints and other coating materials and adhesives.
ISSUE:
Whether the silane coupling agents are classifable under the provision for other adhesives, not elsewhere specified or included, adhesives based on rubber or plastics, in subheading 3506.91.00, HTSUS, or the provision for organo inorganic compounds in subheading 2931.00.50, HTSUS.
2
LAW AND ANALYSIS:
You state that the purpose of these products is to enhance the chemical bonding between an organic material and an inorganic substance, and that their chief use is to increase
the adhesion of glass fiber products to plastic resins. You assert that the products belong to a class of organo silane compounds having two or more reactive groups. One of the groups reacts with inorganic materials to form a chemical bond with the surface material, while to other group is said to react with organic material to from a second chemical bond.
In the technical literature submitted it is noted that the addition of a silane coupling agent is effective in improving the mechanical properties of thermoplastic resins impregnated
with an inorganic filler. It is also stated that adhesive bonding is improved between the organic synthetic resin and an inorganic substrate material when a silane couping agent is
used.
In application the silane coupling agents are said to be applied in a 1 percent aqueous solution to 14 ply glass cloth, air dried, and then heat treated. Epoxy resin plate, an epoxy
resin which is a liquid in its uncured state, is laminated with a curing agent to the glass cloth, through the application of heat and pressure. In this process the coupling agents do not make the bodies adhere but assist in the bonding of the glass to the liquid matrix resins. The resin subsequently hardens to form objects such as fiber reinforced plastics or composite materials.
It should be noted that the products could be made without the organofunctional silanes. The silanes are not the primary bonding agents but act as cross linking or coupling agents,
and when used in low concentrations, become part of the plastic material system, that, on curing, bonds the glass cloth together.
For tariff purposes, it is well settled that a product which actually bonds two surfaces together is a cement, rather than products which merely improve a cement's bonding
capabilities. United States v. Naftone, Inc., 74 Cust. Ct. 1, C.D. 4578, affd., C.A.D. 1166, and Norton & Ellis, v. United States 52 Cust. Ct. 76, C.D.2440.
3
HOLDING:
Organofunctional silanes described are classifiable as other organo inorganic compunds in subheading 2931.00.50. HTSUS. The rate of duty is 3.7 percent ad valorem.
Sincerely,
John Durant, Director
Commercial Rulings Division