Note: Descriptions are shown in the official language in which they were submitted.
~037~18S
This invention relates to an adhesive composition for the
edge gluing of furniture.
The rapid and economical edge gluing of furniture boards
on automatic edge gluing machines has been an important part of the
industrial production of furniture for several years. The edging
materials are secured by means of fusible adhesives which are
melted down in heated containers and applied to the wood in the
molten state.
Wood veneers and plastics of all kinds can be used as
edging materials.
The fusible adhesives which have been mainly used for the
bonding are based on ethylene-vinyl acetate copolymers but they have
the considerable disadvantage of greatly reduced adhesive bond
strength when hot.
Since many articles of furniture are dried at elevated
temperatures after lacquering, or are subjected to high temperatures
in use, there is great interest in the furniture industry for heat-
resistant fusible adhesives for edge gluing. However, in addition
to a good heat resistance, the adhesives must also have good ad-
hesive strength at low temperatures and with the very wide variety
of edging materials.
The present invention provides an adhesive composition
including
I. from 20 to 95 % by weight of a polyamide resin obtainable by
polymerizing a mixture of
(a) from 0.5 to 0.8 equivalent parts of fatty acid component
having a content of dimeric fatty acid of from 70 to 100 %
by weight,
(b) from 0.2 to 0.5 equivalent parts of dicarboxylic acid of
the general formula HOOC - R - COOH in which R represents
an alkylene radical having from 4 to 10 carbon atoms,
(c) from 0 to 0.6 equivalent parts of ethylenediamine and
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lQ37185
(d) from 0.4 to 1.0 equivalent parts of piperazine, the sum of
the equivalent parts of (a) and (b) and the sum of the
equivalent parts of (c) and (d) each being susbtantially 1,
and
II. from 5 to 80 % by weight of inorganic filler, the % by
weight of each of components I and II being based on the
total weight of components I and II. The composition may
contain two or more polyamide resins I and/or two or more
inorganic fillers II.
The compositions of the present invention may be used as
fusible adhesives having the required wide spectrum of properties
mentioned above.
The bonds produced with these adhesives exhibit a surpris-
ingly high heat resistance, coupled with good adhesion values in the
cold, even with high proportions of filler. Thus, even with 70 %
by weight of filler, excellent adhesive strengths may be observed,
both at high and low temperatures.
Moreover, the adhesives of the invention present substan-
tially no problems in adhesively bonding the usual edging materials.
As edging materials there may be used, for example, maple,
teak, a wide variety of wood veneers, melamine-formaldehyde and
urea-formaldehyde resins, polyesters and polyvinyl chloride.
The present invention also provides a polyamide resin I
specified above.
; The fatty acid component (a) used for making the above
polyamide resin I may comprise one or more dimeric fatty acids and,
if desired, monomeric fatty acid(s), trimeric fatty acid(s) or
higher polymeric fatty acid(s) or a mixture of any two or more such
acids. The dimeric fatty acid content of component (a) is in the
range of from 70 to 100 % by weight, especially from 80 to 100 ~,
more especially at least 90 %, by weight.
The fatty acid component (a) may be produced according to
~037~8S
known methods by radical, ionic or thermal polymerization of a
monomeric fatty acid(s), preferably in the presence of a catalyst,
especially a clay, followed by distillation. A suitable fatty acid
component (a) has, for example the following composition:
from 0 to 10 % by weight of monomeric fatty acid,
from 80 to 100 % by weight of dimeric fatty acid, and
from 0 to 10 % by weight of trimeric fatty acid.
Suitable monomeric fatty acid starting material for the
fatty acid component (a) are, for example, naturally occurring un-
saturated mono-fatty acids having a chain length of 14 to 22 carbon
atoms, especially 18 carbon atoms.
The dimeric fatty acid or mixture thereof with small a-
mounts of monomeric and/or trimeric and higher polymeric fatty acids
may be hydrogenated by known methods.
Suitable dicarboxylic acids (component (b)) are, for
example, adipic acid, pimelic acid, suberic acid, azelaic acid,
and l,10-decane dicarboxylic acid. Component (b) may comprise a
mixture of two or more such dicarboxylic acids.
The content of ethylene diamine and piperazine components
in polyamide resin I is from 0.0 to 0.6 equivalent parts and from
0.4 to 1.0 equivalent parts, respectively. Preferably the ethylene-
diamine content is from 0.2 to 0.5 equivalent parts and the
piperazine content is from 0.8 to 0.5 equivalent parts.
As will be appreciated by those skilled in the art, the
polyamide component I may be prepared using, in place of, or as
well as, one or more of the above constituents, the corresponding
polyamide-forming derivatives. Suitable derivatives include, for
example, the esters and amides of the free acids a and b, and the
; amides of, and isocyanates corresponding to, the diamines c and d.
The constituents may also be used in the form of their salts.
For example, the polymerized fatty acid(s1 and the dicar-
boxylic acid(s) may be used in the form of their amide-forming
1037~85
derivatives, especially their acid esters, preferably those which
can easily be subjected to aminolysis, such, for example, as methyl
or ethyl esters.
Accordingly, all references in this specification and
claims to acids and amines are meant to include, where appropriate,
corresponding polyamide-forming derivatives thereof.
The polyamide resin I of the invention may be prepared by
known methods, for example by melt-condensa~ion of the acid and
amine constituents under an inert gas at a temperature in the range
of from 140 to 250C, especially at 230C. If desired an anti-
oxidant, for example a dialkylated diphenylamine, may be added to
the acid and amine constituents before melt-condensation.
The polyamide resin binding agent(s) (component I) is
used in admixture with one or more inorganic fillers (component II).
A wide range of inorganic fillers may be used, for example chalk
or barytes. The proportion of filler in the adhesives of the
invention is from S to 80 ~ by weight, preferably from 30 to 70 %
and more especially from 50 to 70 %, by weight.
For special adhesive requirements, the adhesive comp-
osition of the present invention may incorporate, or may be used in
conjunction with, one or more additional substances, for example
other thermoplastic materials such, for example, as polyamide
resins synthesized differently from the binding agent component I,
or ethylene polymers or copolymers or resins, for example, rosin
esters, phenol resins or ketone resins, or plasticisers, for ex-
ample, sulphonamides. It is also possible to add anti-ageing
agents, dyestuffs or pigments.
The composition of the present invention may be prepared
` by melting the polyamide resin I and working-in the filler(s) II
` and, if desired, one or more additives.
Thus, the present invention also provides a process for
preparing the composition of the invention which comprises in-
corporating into one or more polyamide resins I specified above,
.
~037185
before, during or after the formation thereof, one or more in-
organic fillers II in an amount of from 5 to 80 % by weight, based
on the total weight of polyamide I and filler II. If desired, one
or more additives as mentioned above may also be incorporated into
the composition at any stage in its preparation.
The composition of the present invention is used to unite
two surfaces by applying the adhesive composition of the present
invention to one or both surfaces and bringing the surfaces to-
gether, the adhesive composition being fused so that an adhesive
bond is formed. More especially this method is used for edge
gluing a wooden substrate, wherein a composition of the invention
is applied to a surface of the wooden substrate and/or the surface
of a wood veneer or plastics edging material, and the substrate
and edging material are pressed together, the composition being
at such a temperature between the substrate and edging material
that an adhesive bond is formed.
The edge gluing may be carried out with the usual edge
gluing machines provided for this purpose, the edge glue being
applied from the melt either to the edge of the board or to the
edging material, and an adhesive bond being produced by subsequent-
ly pressing the edging material on the edge.
However, it is also possible to use edging materials that
have been precoated with the edge glue to be used in accordance
with the invention. In this case the edging material is pressed
on the edge with the application of heat.
An example of edge gluing using the composition of the
present invention will now be described, with reference to the
accompanying drawing which is a prespective view of an e~dged
wooden substrate.
A heat-resistant gluing composition 1 of the present
invention is applied, if desired as a melt, to the surface of a
wooden substrate 2 or to the inner surface of an edging strip 3 of
- iO3718S
plastic or wood veneer and the wooden substrate 2 and the inner
surface of t'ne strip 3 are brought together, if necessary with the
~urther application of heat, so that the composition 1 is fused
and an adhesive bond is formed.
The following examples illustrate the invention.
EXAMPLES
Preparation of polyamide resins
Polyamide resin A
The resin was prepared from the following constituents:
0.65 equivalent parts of polymeric tall oil fatty acid having a
dimeric fatty acid content of 96 ~ by weight (400 g),
0.35 equivalent parts of azelaic acid (71.66 g),
0.4 equivalent parts of ethylenediamine (26.0 g), and
0.6 equivalent parts of piperazine (55.96 g).
The above constituents and 8 g of a dialkylated diphenyl-
amine as anti-oxidant, were heated in a three-necked flask provided
with a thermometer, stirrer, condenser and receiver for 2 hours
with stirring and in an atmosphere of nitrogen up to 230C.
The temperature of 230C was maintained for a further 4
hours. During the last two hours a vacuum of 20 Torr was applied.
- The product so obtained had an amine number of 1.5, and
acid number of 3.1 and a ring-and-ball softening point of 141C.
Polyamide resins B to E were prepared in a similar man-
ner from the constituents shown below.
Polyamide resin B
0.55 equivalent parts of polymeric tall oil fatty acid having a
content of dimeric fatty acid of 92 % by weight,
0.45 equivalent parts of azelaic acid,
0.25 equivalent parts of ethylenediamine, and
0.75 equivalent parts of piperazine.
The product thus obtained had an amine number of 0.9,
an acid number of 5.4, and a ring-and-ball softening point of 137C.
-- 6 --
Polyamide resin C lQ37~85
0.75 equivalent parts of polymeric tall oil fatty acid having a
content of dimeric fatty acid of 98 % by weight,
0.25 equivalent parts of suberic acid,
0.50 equivalent parts of ethylenediamine, and
0.50 equivalent parts of piperazine.
The product thus obtained had an amine number of 1.2,
an acid number of 3.5, and a ring-and-ball softening point of 151C
Polyamide resin D
0.75 equivalent parts of polymeric tall oil fatty acid having a
content of fatty acid of 96 % by weight,
0.25 equivalent parts of adipic acid,
0.20 equivalent parts of ethylenediamine, and
0.80 equivalent parts of piperazine.
The product thus obtained had an amine number of 0.5,
an acid number of 8.9, and a ring-and-ball softening point of 139C.
Polyamide resin E
0.50 equivalent parts of polymeric tall oil fatty acid having a
content of dimeric fatty acid of 80 % by weight,
0.50 equivalent parts of decane dicarboxylic acid,
0.20 equivalent parts of ethylenediamine, and
0.80 equivalent parts of piperazine.
The product thus obtained had an amine number of 0.8, an
acid number of 5.2, and a ring-and-ball softening point of 154C.
Preparation and testing of the fusible adhesive
Fusible adhesives were prepared by intense mixing of the
binding agent and filler at temperatures of 200C. The binding
agent and filler used, as well as their relative proportions, are
given in Table I.
Table I ~037~5
Example Binding agent Filler Parts of Parts of
No. _ l binding agent: filler
1 Polyamide resin A chalk 50:50
2 Polyamide resin A chalk 30:70
3 Polyamide resin A chalk 70:30
4 Polyamide resin A barytes 70:130
Polyamide resin B chalk 35:65
6 Polyamide resin C chalk 50:50
7 Polyamide resin D chalk 50:50
8 Polyamide resin E barytes 50:50
In the case of adhesive bonds having thermoplastic binding
agents the heat resistance is best measured by a test over a long
time because the longer lasting action of a force clearly indicates
whether the flow is more or less strong.
Such a "heat resistance test" for testing fusible adhes-
ives for edge gluing (WPS 68) is described in "Adhasion", Number 1,
(1969).
The heat resistances obtained by this method with the
usual edge glues, based on ethylene-vinyl acetate copolymers, are
at most 80 to 90C.
The heat resistances obtained with the edge glues of
examples 1 to 8 are shown in the following Table II.
10~5
Table II
Edge glue of Heat resistance (WPS 68)
Example No.
1 135 - 140C.
2 135 - 145C.
3 130 - 135C.
4 125 - 135C.
135 - 140C.
6 110 - 120C.
7 130 - 140C.
8 125 - 130C.
The edge glues of examples 1 to 8 exhi~it at 0C, room
temperature and 70C good adhesion on edging strips of maple, teak,
polyester resin laminate, melamine resin laminate, poly-vinyl
chloride and poly-acrylonitrile-butadiene-styrene.
.
