Title of Invention

AN ADHESIVE POWDER

Abstract The present invention relates to an adhesive powder for bonding flat, closed, or porous substrates, comprising: i) a thermoplastic polymer component that is a low-melting polyamide. Polyester or polyurethane, or polymer blend of at least one of low- melting polyamides, polyesters and polyurethanes in a proportion of 25 to 95% by weight; ii) at least one epoxy resin component that is solid at room temperature in a proportion of 5 to 75% by weight; and iii) at least one pre-adduct of an epoxy resin and a polyamine that is solid at room temperature in a proportion of 0 to 25% by weight. The adhesive powder is capable of being applied in a first step to a first substrate so as to be physically bonded to the first substrate and thereby produce an intermediate product that is non-adhesive at room temperature and stable in storage. The first substrate is capable of being bonded to a second substrate in a second step by applying an increased temperature and pressure, the two substrates being bonded in the second step by the powder components being chemically cross-linked or post- crass-linked among one another, and being subsequently cooled.
Full Text

Adhesive powder
Description
Technical Field
PU The invention is concerned with the preparation of an 5ir adhesive powder, for joining flat, closed or porous ^^ substrates, m connection with which the adhesive
powder is applied in a first step to a first substrate, and a storage-stable intermediate which is non-tacky at room temperature is produced, and in the second step the first substrate is joined to a second substrate by application of increased -temperature and pressure.
Prior Art
Commonly known are adhesive powders based on thermo
plastics, which can be applied to the substrate that is
to be bonded and which result in a non-tacky, storage-
«r-- stable intermediate. Joining to a second substrate
^ takes place by the application of heat under pressure,
i and the adhesive film is solidified by purely physical
—> means, by cooling- A disadvantage of the hot-melt or
,4C^ heat-seal adhesives is that the temperature stability
iJ of the bond produced is limited by the melting range of
the thermoplastic used. Additionally, in the case of
-^ n certain bonds, the low formulated melting point of the
t:^ copolymers and the associated low crystallinity also
*^-^ reduces the stability of the bond to hydrolysis and
: . solvents.
(\^l Considerably better properties in respect of bond
• j strength and stability to hydrolysis and solvents may
"^^^ be achieved when using epoxide-based adhesives.
X^ ] However, these adhesives in turn have the disadvantage
jfj;^ ■ that they are not suitable for elastic bonds which are
I.,^ subjected to bending stresses. As two-component

systems, moreover, they have the disadvantage that .they must always be mixed and subsequently applied, in liquid or paste-like form, shortly before the bonding operation. It is therefore not possible to store or to dispatch the adhesive-coated materials. As a one-component system, they generally have to be stored at low temperatures, in order to maintain their functionality, or are crosslinking only at temperatures above 150°C. In this case the reaction times are in some cases very long, thereby imposing high thermal loads on the substrates that are to be joined.
Description of the Invention
The invention is based on the object of creating an adhesive powder which may be applied to a first substrate, forms a firm bond with the substrate at room temperature, and is stable on storage. This storage-stable intermediate, which is non-adhesive at room temperature, should be bondable with a second substrate within a very low temperature range and with low pressures. Consequently, the reaction time should be very short.
The proposed object is achieved with an adhesive powder of the generic type specified at the outset, in accordance with the invention, by the combination of the following constituents. The powder consists of a thermoplastic polymer with a fraction of from 25 to 95% by weight and at least one epoxy resin which is solid at room temperature, with a fraction of from 5 to 75% by weight, and, if desired, at' least one preadduct of epoxy resins and polyamines which is likewise solid at room temperature, with a fraction of not more than 25% by weight. In the course of the application of the adhesive powder to the first substrate in a first step, a predominantly physical attachment of adhesive powder to the substrate takes place, while the joining of the

two substrates takes place in the second step by chemical crosslinking or post-crosslinking of the powder constituents with one another and subsequent cooling. The mixture of the chosen compounds therefore makes it possible to produce a non-tacky, storage-stable substrate with an adhesive film which, when applied to the substrate, bonds to the substrate primarily by physical means. Following the cooling operation, the adhesive film possesses latent reactivity. In the course of the operation of lamination to a second substrate, with a higher temperature than during the operation of application to the first substrate, the adhesive film is activated, and crosslinking takes place. Surprisingly, it has been found that the product produced has improved stability to temperature and also to hydrolysis and solvents in comparison to purely thermoplastic adhesives and, moreover, has an improved elasticity in relation to products comprising epoxy-based adhesives. The reason for this is crosslinking of the polymer with the epoxy resin. It was surprising, furthermore, that the crosslinking of the components commences at significantly lower temperatures. Depending on the composition of the adhesive powder, crosslinking from just 90°C was achievable. Crosslinking also took place with an extremely short reaction time.
The fraction of the thermoplastic polymer may vary within wide ranges, although a fraction of from 50 to 90% by weight is preferred. The amount of the epoxy resin is much lower. It is preferably from 10 to 50% by weight. Where a preadduct is used, its fraction is not more than 25% by weight.
Suitable thermoplastic polymers are low-melting polyamides, polyesters, polyurethanes and/or vinyl copolymers containing the functional side groups carboxyl-, amino-, amido- and anhydro-. It is also

possible, for the thermoplastic polymer,.to be a polymer blend consisting of low-melting polyamides, polyesters, polyurethanes and/or vinyl copolymers containing the functional side groups carboxyl-, amino-, amido-, anhydro-- The polymers are constructed from linear or branched monomers. The polyamide may also be formed from one or more of the following monomers:
- at least one at least difunctional carboxylic acid,
- at least one at least difunctional amine
- at least one o-aminocarboxylic acid
- at least one lactam.
The polyester is produced from one or more of the following monomers:
- at least one at least difunctional carboxylic acid,
- at least one at least difunctional alcohol,
- at least one co-hydroxycarboxylic acids
- at least one lactone.
The polyurethanes may be assembled from diisocyanates, polyols and diols.
Epoxy resins which are solid at room temperature preferably comprise reaction products of epichloro-hydrin with bisphenol A and/or reaction products of epichlorohydrin with bisphenol F. It is also possible for the epoxy resin to comprise polyfunctional epoxides. These include, for example epoxidized novolaks.
The preadduct of epoxy resins and polyamines, which is likewise solid at room temperature, consists of reaction products of epoxy resins based on bisphenol A and polyamine and/or reaction products of epoxy resins based on bisphenol F and polyamine. Also possible is a preadduct of epoxy resins and polyaminoamides formed from polyamines and dimeric fatty acids.
Depending on the intended application and nature of the substrates, in a further embodiment of the concept of

the invention, it. is ,possible, for the. adhesive .powder to be blended with further additives. Suitable additives in this context include low-melting resins and/or waxes having melting points of below lOOoC, preferably below 90°C, and/or dyes and/or mineral and/or organic fillers. The fraction of these additives should not exceed a total of 10% by weight. The use of low-melting resins and/or waxes is particularly appropriate if the operation of application to the first substrate is to take place at very low temperatures. Dyes influence the coloration. Metallic fillers influence the thermal conductivity. Their weight fraction may be higher.
Apart from the special nature of the low-melting resins or waxes, it is important that the thermoplastic polymer or the epoxy resin has a first melting point which is different from that of the two other components and lies below 130°C, preferably below 100°C, and has a softening point between 50 and 90°C. This ensures that, in the course of the operation of application to a first substrate, a bond to the substrate takes place only by superficial melting of the thermoplastic polymer or of the epoxy resin, while in the case of the other component or components no melting takes place as yet. A consequence of this is that the melting point of the other component or of the two other components is higher than the first melting point of the thermoplastic polymer or epoxy resin. It is found, however, that the second melting point of the other component or components need only lie slightly above the first melting point in order for good results to be achieved. Use is therefore made of epoxy resins whose melting point lies below 130°C, preferably below 100°C. This makes a significant contribution to minimizing the energy requirement for the bonding of the two substrates.

The temperature at which the powder is applied to the substrate is generally from 5 to 100C above the melting point of the component having the lowest melting point. As already indicated above, it is also possible for the adhesive powder to be fixed on the first substrate at the first increased temperature, by melting of the additives. In this case, the bonding of the adhesive film to the first substrate takes place by purely physical means. Chemical crosslinking is initiated only when the two substrates are joined to one another at a second increased temperature, for example by hot compression. With this approach as well, crosslinking of the principal components with one another takes place, thereby giving a product possessing high stability and flexibility.
It is noted that different application techniques are available for the application of the adhesive powder to the substrate or substrates.
For the lamination, for example, adhesive bonding by means of a heat source comprising a high-frequency field is possible, especially if metallic fillers are present in the adhesive powder.
In order to achieve a highly uniform adhesive film on the substrate, the particle size of the adhesive powder is chosen to be smaller than 200 jim, preferably smaller than 100 jam.
In accordance with the concept of the invention it is also possible for the second substrate likewise to be provided in a first step with the adhesive powder. Where necessary, this may assist the operation of adhesive bonding in the course of lamination.

Implementation .of; the Invention
Example 1
In a stirred tank a powder mixture of a thermoplastic is prepared, comprising a polyamide, an epoxy resin, a polyamine-epoxide preaddulate, a wax and an amorphous silica. The weight fractions in the above order, in %, are 64.6; 27.6; 5.3; 2.0; 0.5. The polyamide chosen is a product bearing the commercial designation Platamid H 103PA80 and the epoxy resin chosen is a product bearing the designation Epikote 1002. Before being mechanically mixed, the individual components are ground to particle size of below 100 |am. The mixture thus prepared is stirred to a paste by customary methods, using water and a paste base comprising dispersant, flow assistant and thickener, and it is applied by the brushing method to one side of a nonwoven. Subsequently, a drying temperature of 95°C is applied. The nonwoven which has been provided with the adhesive powder exhibits good storage stability. When wound up into rolls, the nonwoven webs did not stick to one another, and the adhesive powder adheres firmly to the surface of the nonwoven.
The nonwoven produced in this way was placed on a woollen fabric and passed together therewith through a continuous press, with application of pressure and heat. The pressing temperature was 1200C, with a pressing pressure of 3 bar and a residence time of 30 seconds. The laminate produced in this way was highly stable in the sense of the objective.
Example 2
A powder prepared in the same way, with a polyamide fraction of 62.5% by weight, an epoxide fraction of 32.5% by weight (Epikote 1055) and a wax with 4% by

weight, is processed to a paste with 1% by weight of silica as processing assistant and water and also paste base. The paste is applied to a nonwoven at room temperature and dried at 105°C in a continuous oven. The nonwoven had good storage stability. The laminating operation was conducted at a pressing temperature of 130°C. The laminate produced exhibited high temperature stability and solvent stability.



Claims
Adhesive powder for joining flat, closed or porous substrates, in connection with which the adhesive powder is applied in a first step to a first substrate, and a storage-stable intermediate which is non-tacky at room temperature is produced, and in the second step the first substrate is joined to a second substrate by application of increased temperature and pressure, characterized by the combination of the following constituents: i) a thermoplastic polymer, with a fraction of
from 25 to 95% by weight, and ii) at least one epoxy resin which is solid at
room temperature, with a fraction of from 5 to
75% by weight, and if desired iii)at least one preadduct of epoxy resins and
polyamines which is solid at room temperature,
with a fraction of not more than 25% by
weight, where in the course of the application of the adhesive powder to the first substrate in a first step a physical attachment takes place and the joining of the two substrates takes place in the second step by chemical crosslinking or post-crosslinking of the powder constituents with one another and subsequent cooling.
Adhesive powder according to Claim 1, characterized in that the fraction of the thermoplastic polymer is from 50 to 90% by weight, the fraction of the epoxy resin is from 10 to 50% by weight and the fraction of the preadduct is not more than 25% by weight.
Adhesive powder according to Claim 1 or 2, characterized in that the thermoplastic polymer is a low-melting polyamide, polyester, polyurethane

and/or vinyl copolymer containing the functional side groups carboxyl-, amino-, amido-, anhydro-.
Adhesive powder according to one of Claims 1 or 2, characterized in that the thermoplastic polymer is a polymer blend consisting of low-melting poly-amides, polyesters, polyurethanes and/or vinyl copolymers containing the functional side groups carboxyl-, amino-, amido-, anhydro-.
Adhesive powder according to one of Claims 1 to 4, characterized in that the polymers are constructed from linear or branched monomers.
Adhesive powder according to one of Claims 1 to 5, characterized in that the polyamide is formed from one or more of the following monomers:
- at least one at least difunctional carboxylic acid,
- at least one at least difunctional amine,
- at least one co-aminocarboxylic acid
- at least one lactam.
Adhesive powder according to one of Claims 1 to 6, characterized in that the polyester is formed from one or more of the following monomers:
- at least one at least difunctional carboxylic acid,
- at least one at least difunctional alcohol,
- at least one co-hydroxycarboxylic acid
- at least one lactone.
Adhesive powder according to one of Claims 1 to 7, characterized in that the polyurethanes are assembled from diisocyanates, polyols and diols.
Adhesive powder according to one of Claims 1 to 8, characterized in that the epoxy resin which is

solid at room temperature comprises reaction
products of epichlorohydrin with bisphenol A and/ or reaction products of epichlorohydrin with bisphenol F and/or reaction products of epichlorohydrin with novolaks.
Adhesive powder according to one of Claims 1 to 9, characterized in that the epoxy resin which is solid at room temperature comprises polyfunctional epoxides.
Adhesive powder according to one of Claims 1 to
10, characterized in that the preadduct of epoxy
resins and polyamines which is solid at room
temperature comprises reaction products of epoxy
resins based on bisphenol A and polyamines and/or
reaction products of epoxy resins based on
bisphenol F and polyamines.
Adhesive powder according to one of Claims 1 to
11, characterized in that the preadduct of epoxy
resins and polyaminoamides which is solid at room
temperature comprises polyamines and dimeric fatty
acids.
Adhesive powder according to one of Claims 1 to
12, characterized in that the adhesive powder is
additionally blended with further additives.
Adhesive powder according to one of Claims 1 to
13, characterized in that the additives of low-
melting resins and/or waxes having melting points
of below 100°C, preferably below 90°C, and/or dyes
and/or mineral and/or organic fillers.
Adhesive powder according to one of Claims 1 to
14, characterized in that the fraction of the
additives is not more than a total of 10% by

Adhesive powder according to one of Claims 1 to
15, characterized in that the additives are
metallic fillers.
Adhesive powder according to one of Claims 1 to
16, characterized in that the thermoplastic
polymer or epoxy resin has a first melting point
which is different from that of the two other
components and lies below 130°C, preferably below
lOO0C, and has a softening point of between 50 and
90°C.
Adhesive powder according to one of Claims 1 to
17, characterized in that the higher, second
melting point of the other component or of the two
other components lies below 130°C, preferably
100°C.
Adhesive powder according to one of Claims 1 to
18, characterized in that the adhesive powder is
fixed on the first substrate at the first
increased temperature by melting of the additives.
Adhesive powder according to one of Claims 1 to
19, characterized in that initiation of chemical
crosslinking takes place at a second temperature
during joining to the second substrate by hot
compression.
Adhesive powder according to one of Claims 1 to
20, characterized in that the particle size of the
adhesive powder is smaller than 200 µm, preferably
smaller than 100 µm.
Adhesive powder according to one of Claims 1 to
21, characterized in that the second substrate is

likewise provided with the adhesive powder in a
first step.
Adhesive powder according to one of Claims 1 to 22, characterized in that the powder is heatable in a high-frequency field.

Documents:

in-pct-2001-957-che-abstract.pdf

in-pct-2001-957-che-claims filed.pdf

in-pct-2001-957-che-claims granted.pdf

in-pct-2001-957-che-correspondnece-others.pdf

in-pct-2001-957-che-correspondnece-po.pdf

in-pct-2001-957-che-description(complete)filed.pdf

in-pct-2001-957-che-description(complete)granted.pdf

in-pct-2001-957-che-form 1.pdf

in-pct-2001-957-che-form 19.pdf

in-pct-2001-957-che-form 26.pdf

in-pct-2001-957-che-form 3.pdf

in-pct-2001-957-che-form 5.pdf

in-pct-2001-957-che-pct.pdf


Patent Number 210773
Indian Patent Application Number IN/PCT/2001/957/CHE
PG Journal Number 50/2007
Publication Date 14-Dec-2007
Grant Date 08-Oct-2007
Date of Filing 06-Jul-2001
Name of Patentee CARL FREUDENBERG
Applicant Address Hohnerweg 2-4, D-69469 Weinheim,
Inventors:
# Inventor's Name Inventor's Address
1 KALBE, Michael Pralatenweg 30, D-45219 Essen,
2 WAGENER, Silke Im Vogelsang 53a, D-76829 Landau,
3 GRYNAEUS, Peter Blumenstrasse 5, D-69488 Birkenau-Niederliebersbach,
PCT International Classification Number C09J 163/00
PCT International Application Number PCT/EP99/09098
PCT International Filing date 1999-11-25
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 198 56 254.3 1998-12-07 Germany