Note: Descriptions are shown in the official language in which they were submitted.
. ~ .
090(~7~3
' 1
BACKGROUND OF THE INVENTION
The coating of metallic substrates with an
unbonded ply of plasticized thermoplastic resin has been
well established commercially heretofore. The incorporation
in the resin coating compositions of various standard
anti-oxidants, light stabilizers and other conventional
additives has resulted in coated metallic materials mani-
festing a flexibility without cracking, an impact hard-
- ness and resistance to abrasion which makes them parti-
cularly useful in a variety of applications including
chain-link fence.
The metallic substrate of these coated mater-
ials is rendered vulnerable however, where a single-ply
of unbonded plastic is present, because of the relative
~ ease with which the resin coating can be stripped from
'~ 15 the substrate, a particular concern, for example, where
the coated material is chain-link fence and where this
material is used in areas subject to the activity of
vandals, such as heavily industrialized locations,
public playgrounds and the like.
The bonding of certain thermoplastic resin
coatings to a metallic substrate has been known to
reduce this ease of removal. Bonding has been accom-
plished, illustratively, by treating wire, for example,
with a primer heated to an elevated temperature and the
composite of wire and primer passed through a fluidized
bed of vinyl resin powder. The wire substrate used
commercially in the practice of this latter process has
been found to be ungalvanized steel. Inherent in this
process, additionally, has been the formation of a
1 30 microporous coating of limited thickness, i.e., about
7-10 mils, and this vinyl coating has been found to
i evidence reduced resistance to ultra-violet radiation
over a sustained period. The relative thickness of the
coating which can be achieved by this method has been
found to permit corrosive atmospheres even in the ab-
sence of removal of the coating. This vulnerability
is, of course, of particular significance where the
substrate is, illustratively, ungalvanized steel. 'rhe
production of vinyl coated metallic substrates employ-
ing plastisols or organosols of vinyl chlorlde resins
~ .
"`
' ~ '
. lV900~79
:.''
has also been projected, but the combination of stepsincluding particularly the removal of diluents from
the coating and the absorption of plasticizers in the
fusion phase tend to render the processes uneconomic,
both by reason of the reduced speeds at which, for
: example, wire must pass through the coating step, e.g.,
up to about 300 feet per minute, and the high tempera-
; ture baking ovens necessary for fusion, utilizing high
levels of electric energy.
; 10 Securing a plastic composition to a metal
element is disclosed specifically and by way of further
illustration in U.S. patent 3,795,540. The bondlng of
an extruded plastic cover of polyvinyl chloride, rubber,
impregnated paper of preferably polyethylene, for
example, is suggested by this reference using a copoly- -
mer of ethylene and an ethylenically unsaturated car-
;~ boxylic acid, particularly ethylene-vinyl acetate copoly-
mer. This reference is not concerned with a product
capable of being produced at high speeds in a continuous
process and incorporating a significantly superior bond
of coating to substrate. The formation of an adhesive-
coated substrate and a substrate to which the polyethy-
` lene polymer is thereupon applied is undertaken under
inherently slow moving conditions in which the adhesive
must be extruded onto the substrate. Thus, the adhesiveemployed provides a bond between a protective polymeric
coating such as poly (vinyl chloride) and a metallic
substrate which is inadequate particularly for high-
speed metal forming operations; for example, the pro-
duction of wire products such as chain-link fence.
A further method suggested heretofore for
producing a metal component coated with a bonded plastic
composition is that described in U.S. patent 2,531,169
wherein the patentee describes the deposition upon wire
of a phenolaldehyde modified polyvinyl enamel, a ther-
moset lacquer, as an adhesive, with sequential baking,
and, in order to secure the necessary thickness, pass-
ing the wire through the enamelling bath and baking
oven a number of times, after which the enamelled wire
is transmitted through a vinyl dispersion or plastisol
.~ ' . ." ', ' :.
.
oo~
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with heating of the latter coating as well. This
latter coating step is also repeated several times.
This method i.s obviously cumbersome and uneconomic.
- This patent suggests that extrusion techniques are
unsuitable for deposition of thin plies of plastic
material because of the tendency to damage the under-
coat previously placed on the substrate and because
j of non-uniformity in the resulting layer.
. Certain of these disadvantages elucidated,
illustratively, in the disclosure of U.S. patent
2,531,169 are apparent in U.S. patent 3,532,783 wherein
a polyethylene coating is attached by means of a high
density polyethylene modified with maleic acid to a
wire substrate. This latter patent suggests that
polyvinyl chloride may be substituted for polyethylene
if a suitable adhesive can be found. The adhesive
suggested is VMCH, a vinyl chloride-vinyl acetate
copolymer that is deposited only from solution. Under
normal application this vinyl composition is air dried
or baked to eliminate residual solvents. However, even
if force dried, the desired state for application will
be effected only very slowly. Once deposited, in any
event, on the metal substrate with a subsequent over-
coat layer of plasticized vinyl compound, the adhesive
is softened by the plasticizer of the vinyl chloride
resulting in poor bond strength. The process described
in this patent proceeds inherently at a slow pace
because of the necessity to heat the wire substrate
that is to be coated in order to effect a proper
deposition of adhesive. The solid flake adhesive
employed, in addition, presents a material problem in
securing a uniform coat, enhancing the dependency of
the process on the preheating step.
If, accordingly, a product could be devised
comprising a metallic substrate, and particularly
wire, and, as a second layer or ply, a hot melt poly-
amide adhesive capable of bonding firmly the wire
and a further ply of extrudable thermoplastic resin
and particularly polyvinyl chloride or copolymers
thereof having a uniform thickness suEficient to
., , , 1~3~00~
l; ~
provide effective and prolonged protection to the
wire substrate, a product of prolonged life span
would be obtainable, reducing, and indeed, sub-
stantially eliminating the replacement now periodi-
; 5 cally required of materials which are :increasingly
expensive or unavailable, and thus constitute a
significant advance in the state of the art.
Similarly, if an economically and technically feasible,
continuous high speed system of providing a product
such as the foregoing wherein the heat absorbingqualities of the metallic substrate are used to cool
the adhesive could be devised, an advance of signi-
ficant merit would also be effected.
Various and disparate polyamide adhesives
(such as disclosed, for example, in U.S. patents
3,449,272 and 3,377,303) have been proposed generally
for use with polyvinyl chloride and with metals or
other materials but no mode of application, much less
one that is economically efficacious, or capable of
uniform and continuous performance at high speeds;
nor indeed any suggestion as to specific adhesives
appropriate for simultaneous application to metals :
and polyvinyl chloride to secure a permanent bond
is apparent in these teachings.
SUMMARY OF THE INVENTION
It is, therefore, a general object of this
invention to provide a laminate including a metallic
substrate and a protective thermoplastic resinous
ply or coating wherein the coating is bonded to the
substrate in such a manner as to preserve the composite
assembly of coating and substrate over an extended
period of time and under extremes of environmental
attrition not attainab]e heretofore.
It is a further obJect of this invention
to provide means for producing, in a continuous process
and at speeds up to 2000 feet per minute, a wire to
which has been bonded an extrudable thermoplastic resin
.
-: coating of a thickness sufficient to assure protection against extremes of
temperature and h~idity, as well as against abrasion and oxidi~ing agents
such as mineral acids, sea water and other dilute solutions of salt and
alkali, while conveying an asthetically pleasing effect.
A still further object of this invention is to provide a
coated wire such as provided hereinabove which will have a Elexibility
sufficient so that it may be flexed or bent to form chain-link fence fabric
without cracking and in which the thermoplastic resin employed is preferably,
and significantly so, polyvinyl chloride having improved resistance to
peeling and thus to deliverate human effort to destroy it by cutting of the
protective or insulated coating.
Another and particular object of the invention is to provide
a method of bonding a vinyl chloride resin composition to a galvanized
steel wixe suitable for use in chain-link fabric in a high speed process
~ wherein the bonding component is a hot melt polyamide resin containing
; composition.
Accordingly, a novel metallic-based laminate of unique durability,
including significantly improved and effective resistance to attrition by a
vast variety of environmental agents and forces and comprising a metallic
substrate, a polyamide adhesive applied thereto and having critical
parameters of utility and a protective, extrudable thermoplastic resin and
particularly a plastici~ed vinyl chloride resin outercoat permanently bonded .
by said adhesive to said wire has now been devised. In addition, it has
been discovered that the foregoing thermoplastic resin can be bonded to its
metallic substrate or core in a uniform thickness at high speeds in a
continuous manner by means of a hot melt polyamide resinous adhesive
composition; the process employing the heat adsorbing qualities of the
metallic substrate to cool the hot-melt adhesive for effecting bonding at
the linear speeds prescribed herein.
. .
'`- ` 1~9~t~t3
: 6
Thus, the present invention provides
a metallic substrate whereon is disposed a pro- :
~ tective laminate comprising as a first ply a poly-
- amide hot melt adhesive bonded to said substrate,
said polyamide comprising the condensate of
(1) an amide-forming dicarboxylic compolmd
having the formula:
RloOCR3COOR2
. or compounds hydrolyzable thereto, wherein each of
l and R2 is hydrogen, an alkyl group or an aryl
group; and R3 is an aliphatic, cycloaliphatic or an
aryl radical; or
(2) a polymeric fatty acid having a dimeric
fat acid content of at least 90 percent by weight; or
mixtures thereof; and
a diamine of the formula:
.
5 7
~ ~ 0 R ~
R4~X--C_Cn H2n_~6
wherein each of R4, R5, R6 and R7 is a hydrogen atom
or an alkyl radical; X is a nitrogen atom or a carbon .
atom bearing a single hydrogen substituent and n is
an integer of from 1 to 6 inclusive;
the ratio of said difunctional amide-forming
compound to said diamine being wlthin the range of
about 0.5 to 0.7 moles of said difunctional compound
to each mole of diamine; and the molar equivalent
of said polymeric fatty acid to said diamine being
from 0.9 to 1.1 of carboxyl groups to each amine
moiety present in said diamine;
said polyamide having a melt viscosity of . .
10 to 100 poises at 210C.;
and a second ply of an extrudable thermo-
plastic resin adhering to said substrate by means
of said adhesive.
.. . .
, . ,, . , ~ ~ . . .
190(J~
.~: ,,.
Further the present lnvention provides
: a process for applying and bonding a protective
. coating to a metallic substrate that comprises
; applying to a rapidly advancing length of said sub-
; 5 strate a first ply of a molten polyamide resin hot
melt adhesive; said polyamide comprising
~ (1~ an amide-forming dicarboxylic compound
of the formula:
,, 10 RlooCR3CooR2
;`'" .
- or compounds hydrolyazable thereto, wherein each
of Rland R2 is hydro~en, an alkyl group or an aryl
group; and R is an aliphatic, cycloaliphatic or an
aryl radical; or
(2) a polymeric fatty acid having a dimeric
fat acid content of at least 90 percent by welght
or mixtures thereof
and a diamine of the formula:
` 20
: . ,
~' H ~ ~ ~ H
.: 25 R4 C -Cn~2n - ~ R6
wherein each of R4, R5, R6 and R7 is a hydrogen atom
or an alkyl radical; X is a nitrogen atom or a
carbon atom bearing a single hydrogen substituent
and n is an integer of from 1 to 6 inclusive; the
ratio of said difunctional amide-forming compound
to said diamine being within the range of about
0.5 to 0.7 moles of said difunctional compound to each
mole of diamine; and the molar equivalent of said
' polymeric fatty acid to said diamine being from 0.9
. to 1.1 of carboxyl groups to each amine moiety present
in said diamine; said polyamide having a melt viscosity
of 10 to 100 poises at 210C; cooling the said adhesive
composition -to a flow resistant state; extruding a
molten extrudable thermoplastic resin composition onto
~ 0079
said adhesive composition whereby said adhesive com-
position is softened and cooling, whereby said
thermoplasti resin composition is bonded to said
substrate by means of said adhesive composition.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a cross-sectional view of the
laminated product prepared according to the present
10 invention.
Figure 2 is a semi diagrammatic illus-
tration of the method employed according to the
invention in producing the product of Figure 1.
Figure 3 is a perspective view of one form
Of apparatus used in the practice of the process
according to the invention.
Figure 4 is a sectional view of another
and preferred apparatus for use in the practice of
the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The novel product of the present invention
comprises generally a protectively coated metallic
substrate and an extrudable thermoplastic resin coat-
ing bonded thereto by means of a hot melt resinous
polyamide adhesive composition.
The metallic substrate treated according to
the practice of this invention may vary substantially
as to conformation, flexibility and the metal employed.
Illustratively, the process herein described has appli-
cation to relatively smooth metallic surfaces such as
copper, aluminum and aluminum-containing metals in-
cluding aluminum alloys, brass, magnesium, steel,
whether galvanized, ungalvanized, bethanized, aluminum
coated or high strength, low alloy steels in which the
alloy is, for example, chromium, silicon, copper,
nickel, phosphorus alloy (sold by the U.S. Steel
Corporation under the trademark COR-TEN A steel) or a
.. . . . . . . .
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manganese, chromium, vanadium alloy (sold by U.S.
Steel Corporation under the trademark COR-T~N B
; steel), or steel surface-treated with phosphoric
acid for example; and whether in the form of tubing,
H-beams, web constructions, flat plate, cable, fila-
ment or wire strands, and the like. The invention
herein described has particular and unique application,
however, to wire having most desirably a smooth, nodule-
free surface as shown in Figure 1, and that paid out
at high speeds from a coil which, after coating is
completed, may be conveniently reformed as a coil.
The preferred substrate is galvanized wire
suitable for use in the manufacture of chain-link
fence wherein the wire substrate is produced, accord-
ing to processes well known to those skilled in theart, from hot-rolled rods of controlled quality steel.
The rods are cold drawn through dies to reduce the
diameter of the rod while increasing its length.
The cold drawing contributes desirable properties of
higher tensile strength and increased stiffness. The
resulting wire is then conventionally heat dip gal-
vanized using slab zinc.
While the dimensions of the substrate to
be coated are not narrowly critical, where wire is,
for example, being coated, preferred limits have been
found where, illustratively, the wire is to be used
in making chain-link fence having a cross-sectional
diameter within the range of about .076 inch to about
0.192 inch. Indeed, the invention is especially
practicable for use with normally rigid wire of this
diameter and having, in addition, a tensile strength
of 65,000 to 120,000 psi.
The vinyl resins forming the protective
coating are commercially available vinyl halide, and
particularly vinyl chloride, homopolymers, as well
as copolymers containing at least 75 percent by weight
of vinyl chloride and up to about 30 percent by weight
of one or more other polymerized comonomers.
Illustrative of the vinyl comonomers for use in the
lV~OO~Y~3
,
foregoing copolymers are vinyl esters of the follow-
ing general formula:
O
(I) CH O C R
wherein R is a lower alkyl moiety and one preferably
of from 1 to 4 carbon atoms. Illustrative of the
comonomers are vinyl acetate, vinyl butyrate and vinyl
propionate.
The vinyl resins thus employed in the
practice of this invention provide the most signi-
ficantly effective bond according to the practice,
and under the conditions, achieved hereunder in
combination, by way of illustration, with excellent
protective properties including resistance to abra-
sion, weathering oxidation and attack by a variety
of other chemicals while being relatively inexpensive
and easily handled.
; Other significantly less preferred extru-
dable thermoplastic resins which may also be used,
however, in the practice herein described include the
polyamides, such as nylon-6 and nylon-12, which are
pigmented and stabilized for long outdoor exposure.
The foregoing vinyl chloride homopolymers
and copolymers are combined with plasticizer and
preferably mixtures thereof, in an amount by weight of
about 25 to about 40, and preferably about 28 to 32,
parts for every 100 parts of resin (phr). Included
among these plasticizers are liquid plasticizers
among which are the alkyl and alkoxy alkyl esters of
dicarboxylic acids or the esters of a polyhydric
alcohol and a monobasic acid, and more specifically,
phthalate plasticizers, such as dioctyl phthalate,
butyl octyl phthalate, di-2-ethylhexyl phthalate,
di-isodecyl phthalate, N-octyl phthalate, dinonyl
phthalate, diisooctyl phthalate, butyl lauryl phthalate,
- butyl benzyl phthalate, and ethyl phthalylethyl
glycolate; dibasic acid ester derivatives such as
l~gO()~
ll
dioctyl adipate, dioctyl azelate, dioctyl sebacate,
dibutyl sebacate and glyceryl stearate. Also
contemplated as plasticizers are phosphates such
as trioctyl phosphate, triphenyl phosphate and
tricresyl phosphate; as well as chlorinated fatty
acid esters, alkyl epoxy stearates, epoxides of soya
bean oil fatty acid, and epoxy linseed oil.
A wide variety of plasticizers can be
employed in the vinyl polymer by virtue of the parti-
cular adhesives employed herein which are substan-
tially insoluble in the commonly employed vinyl resin
plasticizers.
Other conventional components include
stabilizers and pigments, normally from about 1 to
9 phr,, and preferably about 3.5 to 5 phr. thereof.
These components are well known within the field
and commercially available. The stabilizers employed
- particularly are thermal and light stabilizers, such
as, illustratively, benzophenone and benzotriazole
derivatives usually in an amount by weight of about
0.05 to 0.3 phr., and dibasic lead phosphate or
cadmium and zinc salts in an amount by weight of
about 0.05 to 0.3 phr. Pigments, employed in amount
of 0.0001 to 3.0 phr., are also well known and include,
for example, phthalocyanine green, phthalocyanine blue,
carbon black and titanium dioxide,
The resulting plasticized polyvinyl chloride
resin compositions contain most desirably, no fillers,
extenders or other extraneous matter. The colors or
pigments are stabilized with conventional stabilizers
as aforesaid, have a light fastness that shall with-
stand a minumum Weather-O-Meter exposure of 4000
and up to 5000!hours without any deterioration
(Test equipment operating Light and Water Exposure
Apparatus Carbon - Arc Type) ASTM D 1499, E 42 Type
and 649 as applied to wire and pipe coating respec-
tively. The extrusion grade semi-rigid vinyl resin
utilized will have most desirably a maximum specific
t79
gravi-ty of 1.30 to 1.32 (ASTM D 792); a hardness
of about Durometer A 75 to 95, Shore A durometer
and preferably about 90 to 95; a tensile s-trength
of about 1500 to 3500 (pounds per square inch gauge)
psig and about 270 to 280 percent elongation
(ASTM D 412). This protective vinyl resin is
characterized by high ebrasion resistance, maximum
deformation of 15% at 120C. (Underwriter Laboratories ---
Test Procedure) under a 500 gram load and compression
cut through of 1500 psig to 1800 psig and preferably
170~ to 1800 psig (Bell Labora-tory Test Procedure).
The vinyl chloride resin coating thus
formulated can be applied to the metallic core or
; wire under the conditions recited herein including
exceptionally high speed with uniformity, from a
conventional extruder in effective thicknesses to
achieve a protectively coated wire having all of
the desired properties necessary for imparting an
extended useful life to the product of the invention
under vigorous conditions to which, for example,
chain-link fence, as well as other products formed of
the insulated and protected metallic substrate~s pro-
duced according to the invention, are subjected.
The hot melt polyamide adhesive composi-
tions employed in the practice herein described arehigh molecular weight polymeric polyamide compositions
; thermally stable as melts in the Brookfield melt
viscosity ranges recited hereinbelow and produced
preferably and substantially from one or more unpoly-
merized difunctional amide-forming dicarboxylic com-
pounds or polymeric fatty acids wi.th one or more
diamines as described hereinafter.
The unpolymerized difunctional amide-forming
dicarboxylic acids contemplated for use in preparing
the polyamides useful in the practice of the present
invention are embraced by the general formula:
(II) R 0ocR3cooR2
.` ' ' ' .
~q~90~)7'~'~
` 13
:
or compounds hydrolyzable thereto and including
the anhydrides or halides (preferably the chlorides)
of the acids corresponding to formula II, wherein
~ each of Rl and R2 is hydrogen, an alkyl group con-
i~ 5 taining from 1 to 6 carbon atoms or an aryl, and
~- usually in this event, an aromatic hydrocarbon, radi-
cal containing from 6 to 8 carbon atoms; and R is
an aliphatic, (straight or branched chain~ preferably
saturated radical of from 2 to 20 carbon atoms or,
and indeed less desirably, a cycloaliphatic radical
~` containing from 4 to 20 carbon atoms or an aryl,
` normally an aromatic hydrocarbon, radical containing
from 6 to 10 carbon atoms. R3 is preferably a
straight chain alkylene radical of 4 to 12 carbon
lS atoms; and most desirably from 5 to 7 carbon atoms.
Illustrative of the copolymerizing dicarboxylic acids
coming within the foregoing structural formula II are
succinic acid, adipic acid, sebacic acid, terephthalic
acid, isophthalic acid, phthalic acid, naphthalene
dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid
and 1,3-cyclohexane dicarboxylic acid, and preferably
pimelic acid, suberic acid, and most desirably, and
indeed uniquely so, it is believed, azelaic acid.
The polymeric fatty acids employed in
reaction with the diamines described herein to produce
the polyamide hot melt adhesive used in the practice
of the invention are those formed predominantly of
dimeric fatty acid. For the purpose of this dis-
cussion the term "fatty acid" or "fat acidl' is
intended to encompass monobasic aliphatic acids, and
to include saturated, ethylenically unsaturated and
acetylenically unsaturated monocarboxylic acids,
whether synthetic or naturally occurring. The terms
"monomer" or"monomeric fatty acid", ''dimer" or
"dimeric fatty acid", and "trimer" or "trimeric fatty
acid", or equivalent terms, are intended to describe
the unpolymerized monobasic monomeric fatty acids or
derivatives present in polymeric fatty acids;
,
, .
.
,,
. .
.. ~ogo~t.
14
` the dimeric fatty acids formed by the dimerization
of two fatty acid molecules; and the residual
higher polymeric forms composed primarily of tri-
. meric acids or derivates (containing usually some
higher polymeric forms) respectively.
:~ The term "polymeric fatty acid'7 or gram-
matical variations thereof, as used herein is intended
to be generic to polymerized acids obtained from one
or, normally, more fatty acids and is intended to
incl~de the saturated, ethylenically unsaturated,
and acetylencially unsaturated naturally occurring
and synthetic fatty acids referred to hereinabove
and specifically those containing from 8 to 24 carbon
atoms.
Further illustrative of the foregoing fatty
acids and polymerized fatty acids are those described
in United States patents 3,454,412 and 3,377,303.
The significantly preferred polymeric fatty
acids employed in this invention are fractionated
polymeric fatty acids having in excess of about 90
percent, and most particularly those having at least
95 percent, by weight of ;the total fat acid present
incorporated in the form of the dimer acid. The -
remaining weight percent is composed substantially of
monomeric acid and some higher polymeric forms.
Significantly preferred fatty or fat acids for use
in the practice herein defined, that is, specifically,
the preparation of polymeric fatty acids, are ethyleni-
cally unsaturated monobacis aliphatic acids, containing
from preferably about 10 to 24 carbon atoms, and most
desirably 16 to 20 carbon atoms. Of these the most
preferred are linoleic acid and oleic acid. Mixtures
of these acids are found in tall oil fatty acids,
mixtures which provide a convenient source for pre-
paration of the polymeric fatty acids employed herein.
Illustrative compositions (on a weight percentbasis) of commercially available polymeric fatty acids,
: . . . , . ~. :
t~ 3
.... . .
.
; 15
. :
,.
based on unsaturated C18 tall oil fatty acids that
are subject to fractionation before use in forming
the polyamides employed in the practice of the
inven-tion are:
5C18 monobasic acids (monomer) 5-15%
36 dibasic acids ("dimer") 60.80%
C54 (and higher) tribasic acids
("trimer") 10-35%
The preferred dimer acid cuts (containing
greater than 90 or 95 weight of dimer) percent
referred to hereinabove are, illustratively and
- desirably, fractionated from the foregoing mixtures
by standard high vacuum distillation or solvent ex-
traction methods.
These acids are reacted, in the formation
- of the polyamides employed herein, either as the
acid ~r se or as an equivalent derivative capable
of forming amides in a reaction with a diamine, such
as the lower alkyl alcohol ester, wherein the alkyl
moiety contains from about 1 -to 8 carbon a-toms, of
polymeric fatty acids.
The fatty acid or derivative is fraction-
i ated by, for example, conventional distillation or
solvent extraction methods. They may optionally bepartially hydrogenated to reduce unsaturation using
hydrogen pressure in the presence of a hydrogenated
catalyst in accordance with methods well known to
those skilled in the art to which this invention
pertains.
The unpolymerized difunctional dicarboxylic
amide-forming compounds of formula II above can also
be admixed with the polymeric fatty acids described
hereinabove in forming the polyamide adhesives of the
invention if desired. Preferred for use in these
mixtures are the polymerized fatty acids and unpoly-
merized dicarboxylic amide-forming compounds indlcated
. .
~, . , . . ,; : , .
~L~900'7~
16
as preferred where reaction of members of each
of these groups with the amide-forming diamines
of the invention is described hereinabove. The
proporation of unpolymerized dicarboxylic compound,
preferably an acid, and most particularly azelaic
acid, in mixtures such as the foregoing will normally
constitute at least 50 weight percent of the total
acid content, including any of the compounds of
foregoing formula II and the polymeric fatty acids,
incorporated in the polyamide adhesives utilized
herein.
For the purpose of this invention,
monomeric, dimeric and trimeric fat acid contents
are defined further by a micromolecular distillation
analytical method The method is that of Paschke,
R.E., et al., J. Am. Oil Chem. Soc, IIII (No. 1) 5,
(1954~, wherein the distillation is carried out
under high vacuum (below 5 microns) and the mono-
meric fraction is calculated from the weight of
- 20 product distilling at 155C., the dimeric fraction
is calculated from that distilling between 155C. and
250C., and the trimeric (or higher) fraction is based
on the residue.
The diamine employed in condensation with
one or more of the foregoing unpolymerized difunctional
compounds of formula II or polymerized fatty acids
described herein is one defined by the formula:
. .
~5 j-------
~ o
(III) ~ Cnl~2n~
wherein each of R4, R5, R6 and R7 is a hydrogen atom
or an alkyl radical and particularly a lower alkyl
radical; X is a nitrogen atom or a carbon atom
.
1(J 9~
.
17
bearing a single hydrogen substituent, i.e. C~;
and n is an integer of from 1 to 6 inclusive.
The moiety, Cn H2n is preferably a saturated straight
chain alkylene radical contain:ing 1 to 2 carbon
atoms. Each of R4, R5, R6 and R7 is most desirably
selected from a hydrogen atom or a methyl or ethyl
radical. Particularly preferred of these amide-
forming diamines is N-(N'piperazinylacetyl)
piperazine (l-piperazinyl-l-piperazenyl methyl ketone3
of the formula:
(IV) H ~ 0 ~ H
C -CH2--~J
. Other illustrative copolymerizable diamines
coming within foregoing formula III for use in forming
the polyamides of the invention are 4-(N-piperazinyl-
, acetyl) piperidine; 4- (4' piperidinylacetyl)
piperidine, 4-(N-piperazinyl-3-propionyl) piperidine;
- 4(N-piperazinyl-3-butyryl) piperidine; N-(4-
piperidinyl-4-butyryl) piperazine; N-(N'-piperazinyl
-6-hexanyl) piperazine; 4 (4'-piperidinyl-5-pentanyl)
piperidine; N-(N' piperazinyl-3-propionyl) piperazine,
N(4-piperidinylacetyl) piperazine; N-(2-methyl
piperidinylacetyl) piperazine; N-(2, 5-dimethyl-
piperazinylacetyl) piperazine; N-(2,5-diethyl-
piperzinylacetyl) piperazi~e; 4-[4'-(5-methyl)
piperidinyl acetyl3-2-methyl piperdine); 4-(2,5-
diethylpiperidinylacetyl)- 2',5' - diethylpiperidine;
4-(N-piperzinylacetyl)-2,5-dimethyl-piperidine;
N-(N'-piperazinylacetyl)-2-methyl piperidine;
N-(4-piperidinylacetyl)-2-methylpiperazine; N-[N'-
(2,5-dimethyl piperzinyl) -3-hexanyl]-2,5-diethyl-
piperazine; and 4-[4'(2-methyl-5-ethyl piperidinyl)-
4-hexanyl]-5-methyl piperidine.
,; :'' ~; . : , '
. .
109~0~3
18
The polyamides of the invention, where
formed by reaction of an unpolymerized difunctional
dicarboxylic amide-formlng acid, ester or anhydride
or halide derivative thereof with one or more dia-
mines such as described hereinabove, are preparedby reaction in a ratio of about 0.7 to 0.5 mol of
acid equivalent to each mol of amine using standard
operating procedures well known to those skilled
in the art.
The reactant diamines used in the practice
of the invention are prepared by known and standard
procedures and are themselves well known to those
skilled in the art. The particularly preferred
N-(N'-piperazinylacetyl) piperazine is, for example,
, 15 produced by reaction of chloroacetic acid or an
alkali metal chlororacetate, for example, sodium
chloroacetate, with piperazine to produce N-piper-
azinyl acetic acid which upon reaction with thionyl
chloride yields the corresponding chloride addition
product from which the N-(N'piperazinylacetyl)
piperazine is secured by reaction of the addition
product with additional piperazine and a weak base
such as sodium carbonate, Na2C03.
Where the polyamides for use herein are
prepared by condensation of the diamines with the
foregoing fractionated polymerized fatty acids, the
; reaction is one of one molar equivalent of amine with
! about one molar equivalent of carboxyl group. The
temperature of the reaction of amine and fractionated
' 30 polymeric fatty acid is not narrowly critical but is
, normally within the range of 150C to 300C. The
polyamides are prepared by adding all reactive ingre-
dients to a reaction vessel, where they are heated in
' an inert gas atmosphere with stirring over a period of
time, illustratively, within the range of 1.5 to
3 hours, and preferably about two hours, and under a
vacuum of 25 to 30 inches of mercury. The longer
~()9t~
,
.
19
duration is employed at the lower reaction tempera-
tures. The polyamide is then cooled rapidly and
- the desired hot melt adhesive polyamide recovered.
The substantially equimolar re:Lation of carboxyl
to amine groups in the resulting polyamide provides
a polyamide that is essentially neutral. An excess
of amine or carboxyl groups is permissible however
and within the ambit of the present invention ratios
of amine to carboxyl moieties may vary between about
0.9 to 1.1 to 1 respectively.
The polyamides thus prepared may and will
normally include the conventional additives referred
to, for example, in U.S. patents 3,454,412; 3,398,164;
3,377,303; and 3,449,273.
The polyamide resins or use herein are
those effecting a superior bond with the metallic
substrate and thermoplastic resinous coating at the
temperatures and within the other operating parameters
described hereinbelow.
Thus, in order that the resins be readily
applied preferably as a liquid and in a thickness
necessary for effective bonding of the resin coat and
metallic substrate thereby at the high rates of speed
defined herein and whether prepared using polymeric
fatty acid or unpolymerized dicarboxylic acid component,
it is significantly preferred that they manifest a
softening point of from about 112 Centigrade (C.) to
138C. (233 Fahrenheit (F.~ to 280F.) and preferably
135 to 138C.; a Brookfield melt viscosity of 10 to
100 poises, and preferably 40 to 60 poises, at 210C.;
a tensile strength of from about 400 pounds per square
inch (psi) to 500 psi and preferably about 450 psi
and a percentage (%) elongation of from 400 to 600,
and preferably about 550.
A preferred polyamide formed from conden-
sation of azelaic acid and N-(N'-piperazinyl-acetyl~-
piperazine has an inherent viscosity of about 0.41 to
,
.
V~)~9
~, .
:"
- 0.45 and most desirably about 0.43> when measured
in accordance with ASTM D1243. A 0.28 weight to
~- volume solution of the polyamide, in cyclohexame,
is used for the determination of viscosity at 30
~ 5 centigrade (C).
- The polymeric is compression molded as
. a 6 inch by 6 inch sheet of approximately 0.04
~ inch thickness at a temperature near its melting
;~ point (usually a few degrees lower than the melting
--~ 10 point) and at 40,000 lbs. load or higher using cello-
phane as the parting agent in the mold. From this
~ sheet, test specimens are die-cut to conform to
--~ ASTM 1708-59T.
The test specimen is clamped in the jaws
~ 15 of the Instron. Crosshead speed is usually 0.5
.~ inch/minute at lOOlbs. full scale load. Chart
speed is 0.5 inch/minute. Tensile strength
- (reference: ASTM D-638-52T) is calculated as
Tensile strength = maximum load in pounds
` 20 cross sectional area(sq. inch~
Percent elon~ation is calculated as:
- ~ gage length at break minus
i % Elongation = gage length at 0 load x 10
., gage engt at 0 load
The polyamides employed herein may be,
: 25 and are preferably, used as such, or may have
incorporated therewith conventional additives well
~' - known to those skil~ed in the art, notably inert
inorganic fillers such as calcium carbonate, in
amounts, for example, up to 40 percent by weight
of the adhesive composition, and standard plasti-
cizers such as ortho and para toluene ethyl sul-
fonamide. These plasticizers are employed, illus-
tratively, in amounts bf up to 5, and preferably
up to 3, percent by weight of the total adhesive
j compositions. The incorporation of fillers and
plasticizers, although economically efficacious,
tends to lead to a less effective bond.
.; ~ , . ,
: ,': ' . ', .
~091~ 9
.
21
Tertiary amine-containing compounds or other
base-forming groups tend to be significantly
less preferred in the practice herein described
since they are prone, when heated, to cause de-
;5 composition of the contiguously disposed outer
protecting coating of thermoplastic resin.
The products of the invention and theprocess by which they are prepared are further
illustrated by detailed reference to the accom-
-10 panying drawing wherein the preferred embodiment
of the invention is manifested. Thus, there is
shown in Figure 1 the coated and bonded wire 10
incorporating the metallic substrate 12 preferably
formed of galvanized steel, and surrounding this
substrate; a continuous ply of hot melt polyamide
adhesive 14 as characterized hereinabove and to
which is bonded in turn as the exterior ply, a
coating, most desirably, of a vinyl halide resin
composition 16.
The composite wire product 10 of Figure
1 is prepared in accordance with a preferred embodi-
ment of the invention as shown in Figure 2 wherein
standard-equipment well known to those skilled in
the art is employed, except where otherwise ex-
25 pressly indicated, Thus, a continuous metallic :
wire core 12 is drawn at speeds of up to about
2000 feet per minute through a plurality of treat-
ment zones in which it receives successive resinous
plies (designated by the numerals 14 and 16 in Figure
1) and is subjected to several significant variations
- in temperature.
More particularly, according to this
process a coil of untreated wire 12 is uncoiled
from a supply stand or pay-off frame 20 which ~ay
be of standard design and drawn through successive
treatment zones at a line rate of speed of between
about 200 to approximately 2000 feet per minute
, ,, : '':
.
10900~
22
and preferably within the range of about 800
to about 1500 feet per minute.
: Indeed, in the preferred embodiment,
the esthetic appeal of the coated product as
reflected in the high surface gloss achieved
at the higher line rates of speed, is enhanced
~; while decreasing the cost of manufacture of the
finished product;
~ The initially ~mcoiled wire is, when
desirable, first cleaned by conventional means,
for exampl.e, chemic,al reagents that is, normally,
organic solvents, such as methyl ethyl ketone and
toluene, to remove dust, oil or other foreign
substances from the substrate or core 12. In a
preferred embodiment of this invention a lightly
oxidized layer of zinc and, most desirably a sub-
; stantially monomolecular layer thereof, is present
on the wire surface after cleaning is complete.
This oxidized surface includes, normally> oxides
as well as hydroxides, of zinc which adhere tothe wire surfàce assiduously through the cleaning
operation and result in enhanced adhesion of the
polyamide resin adhesive composition thereto.
The surface of the wire may, optionally, be roughened
by mechanical means to enhance adhesion of the polya-
mide, but it is neither essential nor, indeed,
particularly desirable to do so. After the cleaning
step is completed, utilizing, in a preferred embodiment,
the device of Figure 4 of the drawing, the wire core
12 is transmitted through a crosshead applicator 32
that constitutes the first treatment zone 24. The
fluid adhesive, normally solid at ambient or room
temperatures, is introduced by pumping from an
extruder or alternatively by gravity feeding from
heated holding tank (350-400F.) into the appli-
cator at an elevated temperature sufflcient to
~ .
23
.~.
render it the adhesive fluid for application to
the wire head applicator or die 32. Where an
extruder is employed the adhesive is heated in
part by the frictional or shearing forces exerted
by kneading of the resinous adhesive in the barrel
of a conventional extruder and more particularly
by heating means disposed in conventional manner
~ in a jacket mounted about the feed screw barrel
o~ other passage or mixing chamber through which
the adhesive is conveyed to the applicator head.
Conventional hot melt tanks or glue pots, well
known to those in the art can be used to supply
molten adhesive to the crosshead applicator. The
: applicator 32 at its opposite ends 35 and 36 is
adapted to receive in threaded engagement therewith
threaded dies 37 and 38 having axially disposed
orifices, the entry orifice 29 and the exit orifice
40 respectively, uniform cross-sectional diameter.
;' The first of these orifices 39 defines the point of
., 20 entry of the wire 12 into the first treatment zone
formed by the annular passage or reservoir 34 and
has a larger cross-sectional diameter than the exit
, orifice 40 which forms a sizing die controlling
; the thickness of the a & esive coating applied to
the wire 12 in the ini-tial treatment zone. Inter-
mediate the opposite ends 35 and 36 of the passage
34 there is disposed an entry port 41 through which
the adhesive however fed thereto is transmitted into
the passage which thus serves as a reservoir in
which the molten adhesive is applied to the advancing
wire.
The cross-head applicator is preferred to
secure a substantially uniform coating of adhesive
on the substrate and employing the particular adhe-
sives herein described it is entirely feasible to
do so at the rates of speed coming within the
aO0~79
24
parameters described herein and in a substan-
tially uninterrupted and continuous operation.
Illustrative, but less preferred, alternatives
are however available for use in the practice
of the invention such as the insulated dipping
- tank 27 shown in Figure 3 composed preferably
of rigid double wall construction, containing
an entry orifice 28 with a suitable entry die
(not shown) through which the wire 12 is advanced
into the tank 27 thus preventing leakage of adhe-
sive present in the molten state within the tank
27 from about the advancing wire 12. Heating
elements (not shown) are disposed within or about
the walls of the tank in standard manner to secure
the elevated temperatures required to melt the
normally solid adhesive and achieve the temperature
necessary to effect coating of the wire 12.
Positioned at the level of the entry orifice 28,
but in the wall opposite that 29 in which the entry
.~ 20 orifice 28 is defined, is an exit orifice 31 com-
prising a sizing die of the requisite diameter to
provide the desired thickness of adhesive coating
14 on the wire core 12 leaving the first treatment
zone.
Whichever of the foregoing means of
~t' application is used, however, the temperature to
which the normally solid adhesive ~s elevated to
induce the necessary viscosity and resulting ad-
. hesion to the metal substrate is normally from
; 30 about 300F. to about 450F. and preferably
. about 350F. to about 450F., the temperatures
varying with the particular composition of the
adhesive formulation, and the thickness of the
adhesive coating 14 to be formed. The preferred
range is employed particularly where the limitations
on viscosity of the adhesive are more severe, that is,
`-- lV~ 7~
for example, where the crosshead applicator of
Figure 4 is utilized. Within the preferred para-
meters for practice of the present invention as
defined herein, the temperature of the adhesive
composition when applied in the first treatment
zone is about 350F. to about 450F to effect the
contin~lous uniform coating required. The thickness
of the coating is normally within the range of about
0.20 mils (.00020 inch) to about 5 mils (.004 inch)
and preferably about 3-5 mils (.003-.005 inch).
Upon leaving the first treatment zone
24 the adhesive coated wire passes in a substan-
tially linear manner through the ambient atmosphere,
which is maintained normally at approximately 65F.
to 78F., and constitutes a second treatment zone
42, in which the adhesive is re-turned to a visco-
elastic state. This zone has a length normally
of about 2 to 20 feet for a residence time of about
0.06 second to 6 sec. and preferably about 4 feet
to about 8 feet a residence time of about `.16 to
.6 sec. Desirably the adhesive assumes a flexible,
soft, semi-solid state best adapted for effective
entry into the extrusion die where activation of
the adhesive 14 deposited about the wire 12 in the
third treatment zone occurs, generally over a dis-
tance about 6 feet or a residence time of about
', .24 to .45 sec. The ambient air provides the
cooling medium of the second treatment zone, together,
significantly it has been found with the metallic
core 12 which functions as a heat sink for the
elevated temperatures imparted to the adhesive
in the first treatment zone.
The second treatment zone or cooling span
42 terminates in the third or vinyl resin deposition
zone 43. l'his zone is composed of the annular passage
defined by a cross-head die, also designated in this
.,
:
"`
.
. _ .. .. .
. ,. . ~ ,
109~
" ,
26
embodiment by the numeral 43. The passage through
which the wire is transmitted in this zone may,
illustratively, be smooth b~re of uniform diameter
or tapered to a relatively constricted diameter
intermediate the opposite ends of the passage.
The method involved is well known to those skilled
in the art. The extrusion process involves, by
way of illustration, blending vinyl halide resin
in the form of a fine powder with plasticizer and
i ~
other additives to form pellets, usually. This
thermoplastic resin composition is then fed through
~ a hopper (not shown) into one end of a conventional
: plastic extruder from which the plastic is then fed
.~ onto a standard screw 45 mounted in the circular
passage or barrel 47 with a close clearance between
barrel and screw surface of, for example, 0.001
inch per inch of screw diameter. The screw 45 is
drawn by a variable speed motor (not shown) which
- is capable normally of inducing a screw speed of
30 to 100 revolutions per minute (rpm). The barrel
' 47 is usually heated electrically and together with
the heat resulting from the shearing of the pel
letized vinyl resin-composition advanced through
, the barrel 47 from the hopper by the screw 45
,f 25 attains a molten state as it approaches the extruder
head composed of the constricted passage of the
- adapter 4~ and crosshead die 43~ The faster the
line speed of the wire to be coated, the faster the
speed of screw rotation and the higher the shearing
temperature effected within the barrel 47. The
, temperature induced in the vinyl resin composition
! in the barrel 47 of the screw feed is sufficient to
activate the hot melt adhesive advancing into the
crosshead die from the second treatment zone, where
i 35 the adhesive has been cooled and rendered suffi-
~' ciently solid to pass unimpeded into the cross-head
- ' ' .
-
- die without clogging of the latter at and about
the point of entry of the adhesive-coated wire
into the die.
The temperature attained in the extruder
head or die of the third treatment zone is from
about 300F. to about 425F. and preferably about
350F. to about 400F.; temperatures sufficient
to secure an effective bond between the vinyl
coating and the wire 12 without degradation of
the adhesive or vinyl resin composition.
The coating applied in the crosshead
die of the extruder is most desirably about 0.015
inch to about 0.025 inch in thickness where the
product wire is to be woven into chain-link fence
fabric.
The coated wire product 10 is then
advanced into the final treatment zone 49 prior
to being rewound on the take-up reel 22 driven by
conventional electric motor or other drive means
(not shown).
The final treatment zone comprises an
intermediate air space or heat transfer zone 50
of about 2 to 20 feet or more in length and pre-
ferably about 5 to 15 feet, and a cooling bath
or trough 52 through which cold water is circulated.
The further removed from the cross-head die 43
the water-containing cooling bath 52 is positioned
within the recited parameters the better the
bonding oE the vinyl resin coating 16 secured to
the metallic substrate or core 12, since greater
opportunity is given for activation of the adhe-
sive 14 and a consequently improved bond. The
residence time in the heat transfer zone 50 will
vary within the range of from about 0.08 second
(sec.) to 6 sec. with a preferred range of about
0.2 sec. to 1.2 sec.
.
~ . lV9~ 9
.,
` 28
.. , :
The cooling bath 52, containing desirably
a circulating stream of water operating at a tem-
perature within the range most desirably of 50F.
` to 70F., serves to assure solidification of the
.. 5 adhesive and vinyl resin plies 1~ and 16 respec-
tively, so that the product 10 can be recoiled or
other~ise stored or used after leaving the bath
.~ 52. The residence time in the bath is normally
from about 0.05 minute to about 0.25 minute depend-
ing upon line speed and the length of the bath.
;~ It has been found, using the polyamide
:~ hot melt adhesives described herein, that a sub-
stantially uniform adhesion can be secured of the
outer coat of thermoplastic resin to the metal
substrate without regard for the linear speed of
the process. Similarly, the product prepared at
transitional speeds to and from the foregoing econo-
.. mically advantageous high rates of speed is neither
, inferior nor inconsistent with that prepared at high
.- 20 speeds and thus not subject to discard.
Adhesion is, believed to be improved
according to the practice of the invention by pre-
heating the metal substrate to a temperature of
' from 75F. to 200F. or indeed 250F. prior to appli-
cation of the adhesive in the first treatment zone.
The use of the cross-head applicator is
particularly preferred with the polyamide hot melt
adhesive as indicated above since it permits the
maintenance of smaller volumes of adhesive at the
elevated temperatures at which application to the
- substrate occurs satisfactorily, and thus provides `
that the adhesive need be maintained at these
elevated temperatures for only brief periods of
time, thus appreciably reducing the tendency to
decomposition of the polyamide adhesive to which
it is subject where incorporated, for example, for
application in the dip-tan~ 27 of Figure 3
.
.
)0~9
29
The resinous adhesives thus evolved are
characterized by excellent adhesion to the vinyl
resins and metallic substrates at the temperatures
- and within the other parameters set forth herein.
;~ 5 The coated wire combines, as will be
evident from the accompanying description, means
for producing a product of unusually desirable
characteristics in a significantly efficient and
inexpensive manner.
The following examples are further illus-
trative of the invention. In the examples all parts
: and percentages are by weight unless otherwise
expressly indicated.
Example I
The example illustrates the production
of wire having a protective coating bonded thereto
in accordance with the invention.
A continuous substrate of clean galvanized
steel wire 12 having a cross-sectional diameter of
0.106 inch and a tensile strength of 100,000 psig
is advanced at a rate of 250 feet per minute through
. the entry die of a dip tank applicator such as
described hereinabove and illustrated in Figure 3
! wherein a polyamide hot melt adhesive composition in
the molten state (about 400F.2 is maintained, and
is applied to the wire or filament 12 in a thickness
of about 0 002 inch.
The normally solid hot melt adhesive is
a thermoplastic polyamide resin prepared by charging
fractionated polymerized tall oil fatty acids mani-
festing the :Eollowing properties upon analysis under
gas liquid chromatography:
Saponification Equivalents: 285
Neutralization Equivalent: 290
Monomer 1.1
: ,,;:
, ,, . ,~ . :
~(~9~9
Dimer 98.2
Trimer (and higher poly-
basic acid residue) 0.7
together with N(N' piperazinylacetyl) piperazine
~' 5 into a reactor equipped with a stirrer, thermo-
couple and distillation head. One molar equivalent
of amine is charged to the reactor for each mole of
carboxyl there introduced. The reaction mixture
-is stirred under nitrogen successively for 1.25
hours at 36C. (96.8F.) to 160C. (320F.); 0.75
: hour at 160C. (320F.); 0.5 hour at 160C. (320F.)
~- to 250C. (482F.); 0.5 hour at 250C.; and then
: under vacuum for 2.25 hours at 250C. The adhesive
is characterized by a ball and ring softening point
of 138C.; a tensile strength of 450 psi and a
percent elongation of 550.
From the exit orifice die of the cross-
head applicator or die (32 of Figure 4) termed the
first treatment zone, the wire is advanced in a sub-
stantially linear manner through the ambient atmos-
phere constituting the second treatment zone 40
having a length of about 4 feet, in which the adhe-
sive coated wire is permitted to cool and solidify.
The coated wire is then delivered to the third treat-
ment zone 42 formed by the smooth annular bore ofa cross-head die into which molten vinyl chloride
resin composition marketed under the trademark
COLORITE 9813 Black, a plasticized p~ly (vinyl
chloridej containing low temperature (-20C.)
plasticizer, a mixture of thermal and ultra-violet
stabilizers and pigment with no other fillers,
extenders or other extraneous matter present, is
fed from a conventional screw feed extruder 43,
The vinyl chloride resin composition
feed has a light fastness sufficient to withstand
(1) a minimum Weather-O-Meter exposure of 4000 hours
\
' '
. . .
~V~U7
i ~
:~ 31
without deterioration (Test Equipment Operating
Light and Water Exposure Apparatus Carbon-Arc Type)
ASTM D 1499, E 42 Type E, and (2) an accelerated
aging test of 2000 hours at 145F. without cracking
or peeling. The resin has, in addition, a tensile
strength of 2700 psi, ultimate elongation of 275%;
a specific gravity of 1.30 maximum, a hardhess not
less than Durometer A 90 ~ 5: maximum deformation
of 15% at 120C. under a 500 gram load and a com-
`, 10 pression cut through of 1500 psi; when measured by
; the appropriate test procedures recited in the
description appearing hereinabove. The screw is
rotated in the heated extruder barrel at a rate
sufficient to knead the foregoing resin and exert
a shearing force adequate, in turn, to induce atemperature in the plasticiæed resin being advanced
; in the barrel 45 and the extruder head or die 42
: to about 350F.
The cross-sectional diameter of the die
is sufficient to provide a resin coating of .021
inch and define an outside diameter of about 0.148
inch to the product wire 10 when the coating opera-
tion is complete.
The wire is next passed into the final
treatment zone 49 including a cooling trough 52
in which water is circulated. This trough is
removed from the die 43 by about fifteen feet in
which span the coated wire travels in a linear path
through a room temperature atrnosphere. In this
span the vinyl coating and hot melt adhesive perfect
the bond initiated in the vinyl extruder's cross-
head die and is cooled sufficiently to avoid accu-
mulation of coating rèsin on the guide rolls of
the trough. The coated wire is then advanced through
the trough or dam 52 which is maintained at about
. . . . .. . . ...
` ~ )9~)07S~
,.
32
69F. to 75F. and the finished product recovered
therefrom after a residence time of about 2.5
seconds. This product evidences good adhesion
five minutes after its recovery from the final
treatment zone and may be stripped from the wire
substrate only with difficulty.
Example 2
This example illustrates the use of an
increased line speed in the practice of the inven-
tion.
The procedure of Example 1 is repeated
using a line rate of speed in the various treatment
zones of 600 feet per minute. The plasticized
vinyl resin at the point of application in the
cross-head die achieves a temperature of about 390F.
The surface finish is found improved to a glossy
condition over that of Example 1.
Example 3
This example illustrates the use of a
line rate of speed significantly faster than that
of Example 1 and 2.
The procedure of Example 1 is repeated
using a line rate of speed in the several treatment
zones of about 900 feet per minute. The vinyl resin
has a temperature of about 370F. in the cross-head
die. The surface gloss is substantially improved
over that secured at the lower rates of speed of
Examples 1 and 2. The degree of surface gloss
secured is significant in that the vinyl resin
coating effected is important not only for its
protective character but for its esthetic appeal
as well, particularly where it is to be employed in
the manufacture of chain-link fence.
. .
07~
.
33
Example 4
This example illustrates the use of a
line speed significantly faster than that of the
prior examples.
The procedure of E'xample 1 is repeated
' 5 using a line rate of speed in the several treatment
zones of about 1000 feet per minute. The surface
gloss is excellent, and the adhesion to the wire
`- substrate of the vinyl resin coating as good as
that secured in Example 3. The outside diameter
of the product wire secured under conditions other-
wise identical to those recited in Examples 1 to
4 was 0.148 inch, with a vinyl coat of .021 inch
thickness. The speed of the coating operation is
limited by the take-up capability of the apparatus
used; not by the effectiveness or speed of appli-
cation.
Example 5
This example illustrates the use of a
cross-head die of different construction for appli-
cation to the wire substrate of the hot melt adhe-
si~e.
The procedure of Example 1 is repeated
using a line rate of speed of about 500 feet per
minute and employing the crosshead applicator of
Figure 4 affixed to the discharge port of a heated
holding tank. The entry orifice 39 of the cross-
head applicator has a uniform cross sectional dia-
meter of 0.114 inch to provide a uniform coating
of hot melt adhesive of 0.004 inch on the bare
wire having a diameter of 0.106 inch.
- Example 6
This example illustrates the practice of
the invention as described in Example 1 employing
~ 35 variable conditions coming there within.
. .
, ', ' ,
9~v~
` 34
The procedure of Example 1 was employed
using a line ra~e of speed of about 975 feet per
minute. The cross-sectional diameter of the wire,
the slab zinc surface of which is ligh-tly oxidized
and otherwise brush cleaned, is 0.106 inch. The
temperature of the dip tank along the path of ad-
hesive application was 400F. The adhesive was
-. a polyamide of the type, and the preparation of
which is, described in Example l; characterized by
a ball and ring softening point of about 183C.;
a Brookfield melt viscosity at 210C of about 45
- poises; a polymer tensile strength of about 450
psi; and a percent elongation of about 550. The
;; adhesive is deposited on the wire substrate in a
thickness of 2 mils. The vinyl resin, identical
to that of Example 1 is deposited in the manner
therein described, in a thickness of about 21
mils to provide a coated product wire with an
outside diameter of about 0.148 inch. The adhe-
sive and vinyl resin coatings deposited are sub-
stantially uniform in thickness.
Example 7
This example illustrates the practice of
the invention as applied to different metallic wire
substrate than that employed in the prior examples.
The procedure of Example 6 was repeated
substituting an aluminum alloy wire substrate having
a cross-sectional diameter of 0.120 inch chemically
cleaned to remove oil and other foreign substances
from its surface. The adhesive was applied at a
temperature of 400F. in a thickness of about 2 mils
to the wire which advanced through the various treat-
ment zones at a rate of 400 feet per minute. The
-:
[)79
. `
identical plasticized vinyl chloride resin compo-
sition of Example ~ was extruded into the resulting
` adhesive coat in the manner of Example 6 in a thick-
ness of 13 to 14 mils to provide a finished coated
wire having an outside or cross-sectional diameter
of 0.150 inch. The peel strength of this product
was found to be excellent.
The determination of the extent of bonding
of vinyl resin coating to the me-tal substrate des-
cribed as peel strength where referred to in the
foregoing examples is made using a six inch length
of specimen wire which is suspended vertically from
the grips of a tensile tester. The upper five
inches of this wire sample are stripped of thermo-
plastic resin coating. The other extremity of the
wire that is stripped is positioned within the annu-
lar orifice or band of adjustable diameter of a
steel stripping fixture adapted to receive the wire.
The stripping fixture is, itself, mounted in the
lower grips of the foregoing tensile tester. The
diameter of the orifice is adapted to receive the
stripped wire but not the coated portion of the wire
which is one inch in length and abuts the lower.end
of the stripping fixture. The stripping fixture or
device is, in performance of the test, lowered under
pressure to effect peeling of the bonded resinous
coating from the wire substrate. The maximum ten-
sile load or weight necessary to strip the wire,
characterized as break-down force is recorded on a
load cell of the tensile tester. .
Example 8
This example illustrates the practice
of the invention as described in Example 5 employing
a different polyamide hot melt adhesive.
''
36
;~
The procedure of Example 5 is repeated
, substituting a polyamide resinous h~t melt adhe-
sive for application to the wire substrate in the
applicator of the first treatment zone. The poly-
amide is that prepared by reaction of azelaic acid
and N-(N'-piperazinylacetyl) piperazine in a molar
ratio between 0.5 and 0.7 to 1 respectively in a
reaction vessel under an inert atmosphere according
to conventional procedures to yield upon cooling a
product having an inherent viscosity of 0.43 (using
ASTM Procedure D 1243 and employing a 2 percent
weight/volume solution of the polyamide in cyclo-
hexanane at 30C.); and a Brookfield viscosity at
210C (410F.), poise of 0.99 as determined by
ASTM procedure D-792.
., .
Exam~le 9
This example illustrates the practice of
the invention as described in Examples 1 to 4 inclu-
sive using the polyamide condensate of Example 8.
The procedures of Examples 1 to 4 are
repeated substituting the polyamide condensate of
azelaic acid and N-(N'piperazinylacetyl)- piperazine
of Example 8 for the hot melt adhesives recited in
each of the foregoing examples.
' Varying the linear speed of application
of the hot melt adhesive and vinyl chloride resin
coating has been found to leave relatively unaffected
the degree of adhesion effe~ted. The adhesion -
achieved is however significant in any event as
measured by the peel strength test procedure des-
cribed in Example 7.
Exam~le lO
This examp].e illustrates the practice of
the invention as described in Examples 8 and 9
using a polyamide derived from different acid and
amine components than those of Example 8.
~)90079
37
~ The procedure of Examples 8 and 9 is
- ` repeated using in each instance similarly prepared
polyamide condensates but of s~beric acid and N-
(N'piperazinyl-3-propionyl)-piperazine; wherein
the acid and amine are reacted in a molar ratio
of 0.5 to 0.7 (acid~ to 1 (amine).
'~ Example 11
This example illustrates the practice of
- 10the invention described in Example 3 hereof but
employing a different polyamide hot melt adhesive.
The proce'dure of Exampl'e 5 was repeated `
using the same apparatus and vin~l resin recited '`
therein, a line speed of about 975 feet per minute
and an adhesive application temperature of about
400F. with extrusion of the vinyl resin onto the
adhesive coating at 390F, but employing the
azelaic acid-N (N'piperazinyl acetyl) piperizine
condensate of Example 8 as the polyamide hot melt
adhesive. The protectively coated wire so produced
evidenced an excellent adhesion.
. ;-,.
Example 12
This example demonstr~tes the practice
of the invention utilizing a pre-heating step,
The procedure of Example 11 was repeated
for production of the resin coated wire product
except that the clean wire is pre-heated to a
temperature of about 150~C. prior to entry thereof
into the ~irst treatment zone,
Example 13
This example illustrates the practice
of the invention as described in Examples 8, 9 and
12 utilizing a different polyamide adhesive.
`:
.
.
;:~
7~
;: 38
.~
`~ The procedure of each of Examples
8, 9 and 12 is repeated using a polyamide con-
densate of pimelic acid and 4-(N-piperidinyl-
acetyl) piperidine.
-5
- Example 14
This example illustrates the practice
of the invention as described in examples 8, 9
. and 12 utilizing a different polyamide adhesive.
The procedure of each of Examples 8, 9
and 12 repeated using a polyamide condensate of
azelaic acid and 4-(4'-piperidinylacetyl) piperi-
dine.
,, ~
Example 15
.i
This example illustrates the practice
of the invention as described in Examples 8, 9
and 12 utilizing a different polyamide adhesive.
The procedure of each of Examples 8, 9
and 12 repeated using a polyamide dondensate of
fractionated polymeric fa~ty acid of Example 1
` and 4-~'-piperidinylpropionyl) piperidine.
E~ample 16
~his~ example illustrates the practice
of the invention as described in Examples 8, 9
and 12 utilizing a different polyamide adhesive.
- The procedure of each of Examples 8,
9 and 12 repeated using a polyamide condensate of
; 30 fractionated polymeric fatty acid of Example 1
and N-(N'-piperazinylacetyl) 2-methyl piperidine.
Example 17
This example illustrates the practice
of the invention as described in Examples 8, 9 and
12 utilizing a different polyamide adhesive.
` ~ 1()90U~"~
39
.~
The procedure of each of Examples 8,
9 and 12 repeated using a polyamide condensate
of adipic acid and 4-(2,5-diethylpiperidinyl
acetyl)-2',5'-diethylpiperidine.
xample 18
This example illustrates the practice
of the invention as described in Examples 8, 9
and 12 utilizing a different polyamide adhesive.
The procedure of each of Examples 8, 9
and 12 repeated using a polyamide condensate of
1,4-cyclohexane dicarboxylic acid and 4-l4'-2-
methyl-5-ethyl piperidinyl)-4-hexanyl]-5-methyl
piperidine.
Example 19
: This example illustrates the practice
of the invention as described in Examples 8, 9 and
12 utilizing a different polyamide adhesive.
The procedure of each of Examples 8, 9
and 12 repeated using a polyamide condensate of
naphthalene dicarboxylic acid and N-~21-(2-methyl
piperidinyl)acetyl] piperazine.
Various epoxy and acrylic adhesives
and zinc chromate primers employed under conditions
similar to those recited above evidence normally
either ~light or no adhesion. Where any adhesion
is secured the bond is brittle. Other acrylic ; ,~
resin adhesives such as that sold by Hughson
Chemical Company in a two component system under
the trademark designation Hughson 521 accelerator
#3 (lacquer) modified acrylic adhesive system,
exhibited good adhesion but required that the
system be run at a very reduced line rate of speed.
' '' " ; ,
`- ` 1(~9VO~,9
..
It will be evident that the terms and
expressions which have been employed are used as
. terms of description and not of limitation.
There is no intention in the use of such terms and
expressions of excluding equivalents of the features
shown and described or portions thereof and it is
recognized that various modifications are possible
within the scope of the invention claimed.
"
