Denka Dry Neoprene for Adhesive Applications

제품소개
Denka Performance Elastomer
Denka Dry Neoprene for Adhesive Applications

Introduction

The ability to crystallize differentiates Neoprene from other elastomer-based adhesives. The value of crystallization is the cohesive strength of the adhesive film formed
from Neoprene, which is considerable greater than it would be if formed from an amorphous polymer. The “quick grab” for which Neoprene-based adhesives are noted
is the result of this crystallization. Rapid development of bond strength is of immeasurable benefit to the end user who can use accelerated assembly techniques without
the need for jigging, clamping, etc.

Not all types of Neoprene crystallize at the same rate; Denka™ Neoprene AD crystallizes very rapidly, while other grades, such as Denka™ Neoprene WHV, crystallize more
slowly. Neoprene WRT is highly resistant to crystallization, which enables the adhesive compounder to obtain the desired crystallization rate by blending different types
of Neoprene.

Use

Some of the many end uses for Neoprene adhesives are listed in the table. Liquid dispersion adhesives are included for completeness.

A-Types

A-Types
GRADE	Solution Viscosity	Crystallization	Features
AD 20	35–53	Rapid	Fast crystallizing
AD 40	95-130	Rapid	Fast crystallizing- high viscosity

Solution Viscosity: mPa-s 5% raw polymer in toluene, 25℃

W-Types

W-Types
GRADE	ML 1+4 at 100℃	Crystallization	Features
W M1	34–41	Fast	General purpose- low viscosity
W	40–49	Fast	General purpose- standard viscosity
WHV 100	90–110	Fast	General purpose- medium high viscosity
WHV	106–125	Fast	General purpose- high viscosity
WRT	41–51	Very Slow	Very slow crystallizing; Slower curing than W
WD	100–120	Very Slow	High Viscosity WRT
NPR 2008	Solution Viscosity 52-85	Moderately Rapid	Combination with fast-crystallizing grades

Characteristics

Denka™ Neoprene AD

Neoprene AD is the most commonly used grade of Neoprene for adhesive applications. It crystallizes rapidly, and the speed and extent of it crystallization results in quick
grab and high uncured adhesive strength. Neoprene AD can be exposed to temperatures as high as 70 oC for several weeks without an appreciable change in color or
hardness.

Denka™ Neoprene WHV

In contrast to Neoprene AD, Neoprene WHV is a relatively slow crystallizing type. The polymer is useful in blends with Neoprene AD to increase the solution viscosity of
ordinary cements. When use as a minor component in such blends, Neoprene WHV will not have a significant effect on tack or bond development rate.

Other Neoprene Types

Denka™ Neoprene W is another relatively slow crystallizing type, with a low-to-intermediate viscosity. It may be used to extend the tack range of Neoprene AD with some
decrease in cohesive strength and aggressive bond development. Neoprene WRT is essentially non-crystallizing and is used to formulate adhesives requiring improved
extended tack range or a soft, flexible glue line.

Denka™ Neoprene GNA and GRT are less stable during storage than the Neoprene W types. They are more reactive with isocyanates and curatives and can be used
in formulations that are intended for two-part adhesives or as curable compositions.

Denka™ Neoprene WB provides high gel content without adversely affecting the rheology of the adhesive. It provides good hot bond strength and is particularly
suitable in applications where hot creep resistance is desirable. However, it has essentially no tack, so Neoprene WB must be blended with other Neoprene types
in contact adhesives.