Note: Descriptions are shown in the official language in which they were submitted.
CA 02248123 1998-09-02
~. ~ e - , , .,: .
POLYAMIDE FORMULATIONS FOR EMBOSSED LAMINATES
FIELD OF THE INVENTION
The present invention relates to heat-sealable and formable polyamide
films with high temperature thermal stability. These properties permit the filmsto be used in monolayer structures, such as embossed laminates for high
temperature insulatir g or cushioning applications. A number of film
formulations are described, and some of these are novel resin formulations.
BACKGROUND OF THE INVENTION
Industry is always seeking new packaging and insulating materials that
10 are cheaper and lighter and offer unique properties. In particular, there is a
strong demand in the automotive business to develop materials which are not
only cost effective, but also provide valuable solutions to address the need to
meet ever stricter safety standards. A particular concern is the need for
insulating materials that may be used in high temperature applications such
as in heat shielding vehicle interiors when accidents or engine failures
produce unsafe high temperature conditions which may be harmful to vehicle
occupants at worst, or at best damaging to the interiors of such vehicles
RELEVANT PRIOR ART
In Ng and Farkas PCT Patent Application No. CA94/û0667 filed
20 December 7, 1994 (the disclosure of which is hereby incorporated herein by
reference), there is disclosed a heat-sealable polyamide film which may be
used in multilayered structures for use in packaging. Generally these
polyamides comprise at least one pendant alkyl branch having 1 to 3 carbon
atoms within at least two amide linkages along the polymer backbone and at
25 least one sequence of at least seven consecutive carbon atoms, excluding
carbon atoms in pendant alkyl branches, if any, within at least two amide
linkages along the polymer backbone. Specifically, they are referred to as low
temperature Nylons (LTN).
In Saltman, U.S. Patent No. 5,091,478 issued February 25, 1992 (the
30 disclosure of which is hereby incorporated herein by reference), there are
disclosed partially grafted flexible thermoplastic compositions formed by melt
blending under high shear, a thermoplastic material having available graft
sites, said thermoplastic material being at least one continuous phase of the
:: - ~'S~
CA 02248123 1998-09-02 . ~,, .
, .. . .
composition, an ethylene copolymer containing an unsaturated mono-
carboxylic acid, and a polymeric grafting agent having reactive groups
capable of reacting with the mono-carboxylic acid in the ethylene copolymer
and with the available graft sites in the thermoplastic material. These
compositions have use in a wide range of molding, coating and adhesive
applications, including various automotive applications, wire and cable coating
applications and high temperature adhesive applications.
In Epstein, U.S. Patent No. 4,174,358 issued November 13, 1979,
there is disclosed toughened multi-phase thermoplastic compositions
consisting of essentially one phase containing 60 to 99 percent by weight of a
polyamide matrix resin of number average molecular weight of at least 5000,
and 1 to 40 percent by weight of at least one other phase containing particles
of at least one polymer having a particle size in the range of 0.01 to 3.0
microns and being adhered to the polyamide, the at least one polymer having
a tensile modulus in the range of 1.0 to 20,000 p.s.i., the ratio of the tensilemodulus of the polyamide matrix to tensile modulus of said at least one
polymer being greater than 10 to 1. The polymer is either branched or straight
chain, but the nylon is conventional nylon. The toughened polymer is useful
for making molded and extruded parts.
Typical polyamides, such as Nylon 6 and Nylon 66, do not possess an
adequate combination of thermal stability, formability and heat-sealability for
commercially making embossed laminated structures. This is especially true
when these polymers are first made into film, and then fed to an embossing
and laminating process.
SUMMARY OF THE INVENTION
It has now been found that the basic formulation covered by the
Saltman patent possesses the right combination of high temperature thermal
stability, formability and heat stability to permit the manufacture of resins and
films for use in the heat shielding applications described previously. The
addition of LTN significantly improves heat sealability and formability of the
formulation. Other embodiments of the formulation include elimination of the
polymeric grafting agent, the addition of other tougheners, and increased
levels of the conventional polyamides as claimed in the Saltman patent.
~,~lENi~ED SHE'~
_
CA 02248123 1998-09-02 C~
.
Thus, the invention provides a variety of formulations, based on the
basic Saltman formulation which exhibit properties which make the resultant
resins and films useful in the types of applications envisaged earlier.
Uses of the present formulations may extend to packaging and
5 cushioning applications where high temperature properties are desirable, for
example in stoves, furnaces, aircraft and so forth.
The term "Graft Sites" as used in connection with the polyamide resin
of component i) hereinafter set out is meant to encompass the reactive sites
on the polyamide. These can be at the end of the molecule (amine or
0 carboxyl ends) or on the backbone (amide linkages).
The present films approach polyethylene films with respect to heat
sealability, but their thermal stability is higher than polyolefin films. In
addition, the heat sealing temperature window and forming window are
sufficiently broad to permit their use in many commercial applications. One
important such application is in bubble pack structures for heat-shielding
applications in automobiles, as noted. Typically, the film for such use would
pass an oven test at 200~C for one hour.
The present invention provides a heat formable laminating film made
from a multi-phase thermoplastic resin composition comprising the following
main components:
i) at least one polyamide resin selected from aliphatic and semi-
aromatic polyamides that can be either semi-crystalline or amorphous in
structure having a number average molecular weight of at least about 5000,
having graft sites and forming the continuous phase of the composition,
25 wherein any semi-crystalline polyamides have a melting point greater than
200~C;
ii) at least one polyamide resin comprising at least one pendant
alkyl branch having 1 to 3 carbon atoms within at least two amide linkages
along the polymer backbone and at least one sequence of at least seven
30 consecutive carbon atoms, excluding carbon atoms in pendant alkyl
branches, if any, within at least two amide linkages along the polymer
backbone, the melting point of the polyamide being less than 200~C, having
~)ED SHEET-- -
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CA 02248123 1998-09-02 ~
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graft sites and also forming the continuous phase of the composition, wherein
the semi-crystalline polyamides have a melting point greater than 200~C.
iii) at least one ethylene copolymer, E/X/Y, where E is ethylene and
is at least about 50 % by weight of EIXJY, X is from about 1to about 35 % by
5 weight of an acid containing unsaturated mono-carboxylic acid, and Y is 0 to
about 49 % by weight of a moiety derived from at least one alkyl acrylate,
alkyl methacrylate, alkyl vinyl ether, carbon monoxide, sulfur dioxide, or
mixtures thereof where the alkyl groups contain 1-12 carbon atoms, and
further wherein the acid groups in the acid-containing moiety are neutralized
0 from 0 to about 100% by weight of a metal ion;
iv) at least one polymeric grafting agent which contains reactive
groups selected from at least one of epoxides, isocyanates, aziridines,
silanes, alkyl halides, alpha-halo ketones and aldehydes, or oxazoline, which
reacts with the acid-containing moieties in component iii) and additionally
15 reacts with the graft sites of components i) and ii), and the weight percent of
the monomer(s) containing the reactive groups is about 0.5 to about 15 weight
percent of the polymeric grafting agent, and the remainder of the polymeric
grafting agent contains at least about 50 % by weight of ethylene and from 0
to about 49 % by weight of a moiety derived from at least one alkyl acrylate,
~Y--
alkyl methacrylate, alkyl vinyl ether, carbon monoxide, sulfur dioxide, or
mixtures thereof where the alkyl groups contain 1-12 carbon atoms; and
v) at least one C2-C20 polyolefin selected from polyethylene,
polypropylene, ethylene propylene diene terpolymer, copolymers of ethylene
with vinyl acetate, carbon monoxide, or ethylenically unsaturated carboxylic
25 acids or esters thereof upon which are grafted from about 0.05 to about 5%
by weight of monomers or mixtures of monomers selected from ethylenically
unsaturated acidic monomers or their derivatives including acrylic acid,
methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, 5-
norborene-2,3-dicarboxylic acid, maleic anhydride, monomethyl fumarate and
30 monomethyl maleate; and from ethylenically unsaturated monomers
containing amino or hydroxy functional groups including vinyl pyridines, vinyl
silanes, 4- vinyl pyridine, vinyltriethyloxysilane and allyl alcohol;
-- ~MENDED SHEE~
CA 02248123 1998-09-02
the components being combined in accordance with one of the following
formulation combinations:
~ A. from about 29 to about 54% by weight of component i),
from about 8 to about 70% by weight of component iii), and
from about 0.8 to about 45% by weight of component iv);
B. from about 17 to about 54% by weight of component i),
from about 1 to about 40% by weight of component ii),
from about 5 to about 69% by weight of component iii), and
from about 0.5 to about 45% by weight of component iv);
such that the sum of components i) and ii) equals from about 29
to about 72% by weight;
C. from about 55 to about 90% by weight of component i),
from about 10 to about 45% by weight of components iii) or v) or
mixtures thereof;
D. from about 15 to about 89% by weight of component i),
from about 1 to about 40% by weight of component ii),
from about 10 to about 45% by weight of component iii) or v) or
mixtures thereof; and such that the sum of components i) and ii)
equals from about 55 to about 90% by weight;
E. from about 30 to about 91% by weight of component i),
from about 1.5 to about 70% by weight of component iii), and
from about 0.15 to about 45% by weight of component iv).
It should be noted that each of the above formulations A to E may be
used to prepare film to make the heat formable laminating film of the
invention.
In another embodiment of the invention there is provided a novel multi-
phase resin composition comprising as the main components:
from about 17 to about 54% by weight of (i) at least one polyamide
resin selected from aliphatic and semi-aromatic polyamides that can be either
. =, ~ =
CA 02248123 1998-09-02
semi-crystalline or amorphous in structure having a number average
molecular weight of at least about 5000, having graft sites and forming the
continuous phase of the composition, wherein the semi-crystalline polyamides
have a melting point greater than 200~C;
from about 1 to about 40 % by weight of (ii) at least one polyamide
resin comprising at least one pendant alkyl branch having 1 to 3 carbon atoms
within at least two amide linkages along the polymer backbone and at least
one sequence of at least seven consecutive carbon atoms, excluding carbon
atoms in pendant alkyl branches, if any, within at least two amide linkages
0 along the polymer backbone, the melting point of the polyamide being less
than 200~C, having graft sites and also forming the continuous phase of the
composition; and with the proviso that the sum of components i) and ii) is from
about 29 to v 72% by weight;
from about 5 to about 69% by weight of (iii) at least one ethylene
copolymer, EIX/Y, where E is ethylene and is at least about 50 % by weight of
EIX/Y, X is from about 1to about 35 % by weight of an unsaturated mono-
carboxylic acid, and Y is 0 to about 49 % by weight of a moiety derived from
at least one alkyl acrylate, alkyl methacrylate, alkyl vinyl ether, carbon
monoxide, sulfur dioxide, or mixtures thereof where the alkyl groups contain
20 1-12 carbon atoms, and further wherein the acid groups in the acid-containingmoiety are neutralized from 0 to about 100% by weight of a metal ion; and
from about 0.5 to about 45% by weight of (iv) at least one polymeric
grafting agent which contains reactive groups selected from at least one of
epoxides, isocyanates, aziridines, silanes, alkyl halides, alpha-halo ketones
25 and aldehydes, or oxazoline, which grafting agents react with the acid-
containing moieties in component iii) and additionally react with the graft sites
of components i) and ii), and the weight percent of the monomer(s) containing
the reactive groups is about 0.5 to about 15 weight percent of the polymeric
grafting agent, and the remainder of the polymeric grafting agent contains at
30 least about 50 % by weight of ethylene and from 0 to about 49 % by weight of
a moiety derived from at least one alkyl acrylate, alkyi methacrylate, alkyl vinyl
ether, carbon monoxide, sulfur dioxide, or mixtures thereof where the alkyl
groups contain 1-12 carbon atoms.
~MEN~ED SHEET
_ ...................................................... .. .
CA 02248123 1998-09-02
Yet another embodiment is directed to a novel multi-phase resin
composition comprising as the main components:
from about 15 to about 89% by weight of (i) at least one polyamide
resin selected from aliphatic and semi-aromatic polyamides that can be either
5 semi-crystalline or amorphous in structure having a number average
molecular weight of at least about 5000, having graft sites and forming the
continuous phase of the composition, wherein the semi-crystalline polyamides
have a melting point greater than 200~C;
from about 1 to about 40 % by weight of (ii) at least one polyamide
10 resin comprising at least one pendant alkyl branch having 1 to 3 carbon atomswithin at least two amide linkages along the polymer backbone and at least
one sequence of at least seven consecutive carbon atoms, excluding carbon
atoms in pendant alkyl branches, if any, within at least two amide linkages
along the polymer backbone, the melting point of the polyamide being less
5 than 200~C, having graft sites and also forming the continuous phase of the
composition, wherein the semi-crystalline polyamides have a melting point
greater than 200~C and with the proviso that the total of components i) and ii)
is from about 55 to about 90% by weight; and
from about 10 to about 45% by weight of (iii) at least one ethylene
copolymer, EI~C/Y, where E is ethylene and is at least about 50% by weight of
E/XIY, X is from about 1 to about 35% by weight of an acid containing
unsaturated mono-carboxylic acid, and Y is 0 to about 49% by weight of a
moiety derived from at least one alkyl acrylate, alkyl methacrylate, alkyl vinylether, carbon monoxide, sulfur dioxide, or mixtures thereof where the alkyl
25 groups contain 1-12 carbon atoms, and further wherein the acid groups in the
acid-containing moiety are neutralized from 0 to about 100% by weight of a
metal ion; or
from about 10 to about 45% by weight of (v) at least one C2-C20
polyolefin selected from polyethylene, polypropylene, ethylene propylene
30 diene terpolymer, copolymers of ethylene with vinyl acetate, carbon
monoxide, or ethylenically unsaturated carboxylic acids or esters thereof upon
which are grafted from about 0.05 to about 5% by weight of monomers
~lENDEF~ T
CA 02248123 1998-09-02 r~o~ - . r -
r r
_r . . I - r ~ - -
selected from ethylenically unsaturated acidic monomers or their derivatives
including acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic
acid, crotonic acid, 5-norborene-2,3-dicarboxylic acid, maleic anhydride,
monomethyl fumarate and monomethyl maleate; and from ethylenically
5 unsaturated monomers containing amino or hydroxy functional groups
including vinyl pyridines, vinyl silanes, 4- vinyl pyridine, vinyltriethyloxysilane
and allyl alcohol; or mixtures of iii) and v), in any desired ratio.
In a preferred form of the invention, the ends balance of the low
temperature nylon has been found to affect the processing and properties of
0 the final film product. In other words, it has been found that low temperaturenylon, specifically D12, with balanced or carboxyl rich ends in the formulation
reduces filter pressure drops and melt viscosities during film production, and
improves film dimensional stability during heating - compared to the
incorporation of D12 having amine-rich ends.
A most preferred form of the present formulation comprises from about
17 to about 54% by weight, more preferably, from about 18 to about 47% by
weight, and most preferably, from about 19 to about 40% by weight of Nylon 6
(component i); from about 1 to about 40% by weight, more preferably about
10 to about 40% by weight; most preferably from about 20 to about 40% by
20 weight of Nylon D12 (low temperature nylon), (component ii); from about 5 to
about 69%, more preferably from about 11 to about 58% by weight, and most
preferably from about 15 to about 48% by weight of ethylene EIXIY
(component iii); from about 0.5 to about 45% by weight, more preferably from
2 to 28%, most preferably from about 3 to about 16% by weight of ethylene/n-
25 butyl acrylate/glycidyl methacrylate (component iv); with the total amount ofnylon ranging preferably from about 29 to about 72% by weight, more
preferably from about 38 to about 71 % by weight, and most preferably from
about 45 to about 70% by weight.
It should be noted that for the ranges set out above these may be
30 applied to the various generic components also.
In another preferred form of the invention, the formulation B comprises
from about 55 to about 80% by weight of components (i) and (ii), with the
nylon component always in the majority (the SURLYN~9 and ethylene/n-butyl
- ~ - -- - AM~ND~D SHEEI
. _ ~ . . .
CA 02248l23 l998-09-02
; s ~
acrylate/glycidyl methacrylate components are in the minority), but component
(i) may range from about 20 to about 60% by weight, and component (ii) may
range from about 10 to about 35% by weight.
In every instance, the formulations disclosed herein may include
antioxidants, heat stabilizers or mixtures thereof. Typically these comprise
from about 0.05 to about 5.0% by weight, preferably from about 0.05 to about
2.0% by weight. Organic heat stabilizers have been found to be better than
the metal halide heat stabilizers, such as Cul/KI, in terms of retention of filmphysical properties after oven aging for one hour at 200~C. Irganox~
0 1010/1098 is a preferred example of such a material. This substance also
reduces filter pluggage and reduces pressure during the production of the
film.
Other optional ingredients may be selected from flame retardants, anti-
blocking agents, slip additives, pigments or dyes, processing aids, plasticizers15 and ultra-violet blocking agents. These may be used in suitable quantities as are well known to those skilled in the art.
All of the resir; Formulaatio,ls set forth above may be formed into films
using well known techniques in the art. Such films form part of the novel
aspects of the present invention with respect to the novel resin formulations
20 noted above. It is to be understood that the terms layer, sheet, and film areused interchangeably herein. The term layer may encompass monolayer and
multilayer films as well.
The invention also provides an embossed laminate formed from the
above multi-phase composition. It comprises an embossed layer of the
25 composition heat sealed to an unembossed layer of the same or similar
composition.
In another aspect the invention provides a high temperature heat shield
assembly comprising at least one layer of embossed laminate as described
above, having adhered thereto at least one layer of a reflective material. The
30 assembly may comprise a plurality of layers arranged in suitable sequence to
produce a heat shield effect, with at least one reflective layer as an exterior
layer and at least one embossed laminate layer as an interior layer. The
AMEN~ED SHEE~
.
CA 02248123 1998-09-02 , .
- n- r . - -
~ r
layers of such an assembly are usually adhered by means of suitable high
temperature adhesives, well known to those skilled in the art.
Cushioning and protective assemblies may be constructed in a similar
fashion to the heat shielding assemblies described above.
In yet another aspect the invention provides a method for producing a
heat formed, flexible, thermoplastic, embossed laminate, wherein a resin is
formed by blending the components of one of the formulations described
above, and the resin is extruded, passed through a die and immediately into
an embossing and laminating process.
In a final aspect, the invention provides a method for producing a heat
formed, flexible, thermoplastic, embossed laminate, wherein a resin is formed
by blending the components of one of the formulations described above, and
the resin is extruded and passed though a die to form a film or sheet or layer
which is subsequently subjected to an embossing and laminating process.
The embossed laminate is manufactured in accordance with known
methods and equipment for manufacturing such materials. An example of
both a suitable method and apparatus is described in Fielding U.S. Patent No.
3,586,565 issued June 22, 1971, the disclosure of which is hereby
incorporated by reference. The bosses or cells are generally closed to
20 provide insulating value and may be of any suitable shape, with bubbles,
diamonds, squares and the like being examples of typical shapes.
When the embossed laminated film is prepared using film that has
been stored the film is pre-heated prior to the embossing and laminating
steps.
A typical insulating structure for use in a heat shield application, such
as in motor vehicles comprises at least one layer of the present embossed
laminate adhered to at least one layer of a reflective layer. The reflective
layer may be selected from any number of materials suitable for this purpose.
Examples include metal foil and sheet metal. Alternatively, thin metal layers
30 may be applied to the film surface by standard metallization techniques such
as vacuum deposition.
In alternative applications where high temperature requirements are
not of concern, the structure may comprise at least one embossed laminate
~D S~E~
CA 02248123 1998-09-02
~ r
film layer as described above and at least one layer selected from wood,
paper, and synthetic plastics.
~ A typical high temperature heat insulating structure is found in the
following tabu!ar illustration.
5 Table 1
Metal Adhesive Embosse Center Embosse Adhesive Metal layer-
layer- (high d laminate film layer, d laminate (high Reflective
Reflective temperature) bosses optionally temperature) Layer
Layer coated
with
adhesive
on both
sides
The film usec to make the laminate of this invention s typically from
about 25 microns to about 102 microns thick(1 to about 4 mils). The reflective
layer is typically about 76 microns (3 mils) thick. The films, sheets, layers ofthe formulations of this invention may range in thickness from about 25 to
about 508 microns (1 to about 20 mils), preferably from 12.7 to about 254
microns (about 0.5 to about 10 mils), and most preferably about 25 to about
102 microns (1 to about 4 mils) thick (the last as stated above).
It is also possible to replace one of the outer metal layers with a non-
reflective layer, such as paper, wood, synthetic plastics material or any other
5 suitable materia;.
In the following five tables there are set out the various combinations of
components that may comprise the five different combinations set out earlier
as being capable of being heat formed into embossed laminates. These
tables set out the broad ranges for the components already described and
20 include the preferred and most preferred combinations of components. It will
be apparent, from the earlier description that there are two types of
formulations which are novel, these are those found in Table lll of Formulation
B and Table V of Formulation D. Each of these contains the LTN component.
IBED S~EE~
.
Table 11- Formulation A
Component Broadest Preferred Formulation Most Plt:rer-~d
Formulation Ranges % Byweight Formulation Ranges
Ranges % By Based on Total of Main % By Weight Based on
Weight Based on Components Total of Main
Total of Main (About prefaces each Components
Components Number) (About prefaces each
(About prefaces Number)
each Number)
Component i 29-54 31-52 32-50
Polyamide
Component i 2 5000 2 7500 2 10000
rûly~."i~
Number Average
Molecular Weight
Component iii 8-70 18-65 25.5-60
Ethylene Copolymer
E/XIY
Componentiii 2 50 2 55 2 60
%E
Component iii 1 -35 3-30 5-15
%X'
Component iii 049 0-35 0-25
%y
Component iii 0-100 0-80 0-75
% Neutralkation of
Acid Groups in X by
Metal lon
Component iv 0.845% 3-30.5 5-20.5
Polymeric Grafting
Agent
Component iv 0.5-15 1 -10 1 -7
Polymeric Grafting
Agent
% by Weight of
'' lulll~::la
Containing Readive
Groups as % By
Weight of Polymeric
Grafting Agent
Componentiv > 50 2 55 260
Polymeric Graning
Agent
% By Weight
Ethylene
Component iv o~g 0 85 0 35
Polymeric Grafting
Agent
% By Weight Alkyl
Moiety
= =. - = . = _ _
.. _ .__~ _ _, _, _ _ _ . . .. _ _ _ . -
~ - _ se~
CA 02248123 1998-09-02 ,,
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-
Table 111- Formulation B
Cor"pone"L Broadest Preferred Formulation Most Preferred
Formulation Ranges % By weight Formulation Ranges
Ranges % By Based on Total of Main % By Weight Based on
WeiçJht Based on Cc",.ponenLa Total of Main
Total of Main (About prefaces each Cc"",oolle.,ts
~ Co".~.one"ts Number) (About prefacos each
(About prefaces Number)
each Number)
Component i 17-54- 20-49b 22-45'
Polyamide
Component i 2 5000 2 7500 2 10000
Polyamide
Number Average
Molecular Weight
Component ii 140' 5_35b 10 30C
Poly~l" ,iJe
Component iii 5-69 12-62 18-54
Ethylene
Copolymer EIX/Y
Component iii > 50 2 55 2 60
%E
Component iii 1-35 3-30 5-15
%X
~ Component iii 0-49 0-35 0-25
% Y
Component iii 0-100 0-80 0-75
% Neutralkation of
Acid Groups in X by
Metal lon
Component iv 0.5-45% 2-29 3.5-18
Polymeric Grafting
Agent
Component iv 0.5-15 1-10 1-7
Polymeric Grafting
Agent
% by Weight of
~c ~c" "~, :,
Containing
Reactive Groups as
% By Weight of
Polymeric Grafting
Agent
Component iv 2 50 2 55 2 60
Polymeric Grafting
Agent
% By Weight
Ethylene
Component iv 0~9 0-35 0-35
Polymeric Grafting
Agent % By Weight
Alkyl Moiety
a)i+ii=27- 2,b)i+ii= 34-69, r ) i + ii = 39-6~;
~M~DEI:) SH~ET
-
CA 02248123 1998-09-02 ,,
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Table IV - Formulation C
Component Bn~adeal Fl .:t~r, ed Most ~l ete" ~:d
Formulation Formulation Ranges Formulation
Ranges % By % By weightBased Ranges
Weight Based on on Total of Main % By Weight
Total of Main Co",pone"la Based on Total of
Components (About prefaces Main Components
(About prefaces each Number) (About prefaces
each Number( each Number)
Componenti 55-90 60-80 60-75
Polyamide
Component i 2 5000 2 7500 2 10000
Polyamide
Number
Average
Mc ~-
Weight
Component iii 10~5 20 40 25 10
Ethylene
Copolymer
E/XIY or
Component v
(a grafted
polyolefin) or
mixtures
thereof*
Component iii 2 50 2 55 2 60
% E
Component iii 1-35 3-30 5-15
%X
Component iii 049 0-35 0-25
% Y
Cor"pone"l iii 0-100 0-80 0-75
%
Neul, - n
- of Acid Groups
in X by Metal
lon
* Any ratio may be used.
-- ~DED SH~
, . ~.... . . . . . _
.
CA 02248123 1998-09-02 , _, . ~
A r A _ C' , ; , _ _ ;
Table V - Formulation D
Component Broadest Preferred Most Fl erer. e d
Formulation Formulation Formulation Ranges
Ranges % By Ranges % By % By Weight Based on
Weight Based on Weight Based on Total of Main
Total of Main Total of Main Components
Components Components (Aboutprefaces each
(About prefaces (About prefaces Number)
each Number) each Number)
Component 1 5-89a 25_75b 30_65c
i Polyamide
Component 2 5000 27500 2 10000
i Polyamide
Number
Average
Molecular
Weight
Component 1~0~ 5 35b 10_30C
ii Polyamide
Component 1045 20 10 2540
iii
Ethylene
Copolymer
EIXIY or
Cor,.poner,L
v (a grafted
polyolefin)
or mixtures
thereof
Component ~ 50 2 55 > 60
Component 1-35 3-30 5-15
iii % X
Component 049 0-35 0-25
iii % Y
Component 0-100 0-80 0-75
iii %
NeuL, o
n of Acid
Groups in X
~ by Metal lon
a)i+ii=55-9C b)i+ii=60-80 c)i+ii=60-75
ED~SHEET
_ _ . . . _ _ . . _ _ . ., . _ _ _ _ _ _ . _ _ _ _ . _, , . . _ .
CA 02248123 1998-09-02 ~~r ~ ~~
~ ~ C
Table Vl - Formulation E
CGm,OOl)e.~t Broadest Formulation Preferred Formulation Most Preferred
Ranges % By Weight Ranges % By weight Formulation Ranges
- Based on Total of Main Based on Total of Main % By Weight Based CGr,.?o"e.,~ Co".pc,ner,ts on Total of Main
(About prefaces each (About prefaces each CO~?OnV~
Number) Number) (About prefaces
each Number)
Component i 30-91 32-76 32-65
Polyd" ,i-le
Component i 2 5000 2 7500 2 10000
Polyamide
Number Average
Molecular Weight
Component iii 1.5-70 9-65 18-60
Ethylene
Copolymer EIX/Y
Component iii 2 50 2 55 2 60
%E
Component iii 1-35 3-30 5-15
%X
Component iii 0~9 0-35 0-25
%Y
Component iii 0-100 0-80 0-75
% Neutralkation of
Acid Groups in X by
Metal lon
Component iv 0.1545 1.5-30 3.5-20
Polymeric Grafting
Agent
Component iv 0.515 1 10 1-7
Polymeric Grafting
Agent
% by Weight of
~' hulll~l~
Containing
Reactive Groups as
% By Weight of
Polymeric Grafting
Agent
Component iv 2 50 2 55 2 60
Polymeric Grafting
Agent
% By Weight
Ethylene
Componentiv 0-49 0-35 . 0-35
Polymeric Grafting
Agent
% By Weight Alkyl
Moiety
M~DED SHEEl
, .
:~,
CA 02248123 1998-09-02
6 .; ~ ~D
r. ~ r r r ~ ~ r ~
COMPONENT j) The polyamide of component i) embraces those semi-
crystalline and amorphous resins having a number average molecular weight
of at least about 5000 and commonly referred to as nylons. Suitable
polyamides include those described in U.S. Patents Nos. 2,071,250;
2,071,251; 2,130,523; 2,130,948; 2,241,322; 2,312,966; 2,512,606; and
3,393,210. The polyamide resin can be produced by condensation of
equimolar amounts of an aliphatic or aromatic dicarboxylic acid containing
from 4 to 12 carbon atoms with a diamine, in which the diamine contains from
4 to 14 carbon atoms. Excess diamine can be employed to provide an excess
0 of amine end groups over carboxyl end groups in the polyamide. Examples of
polyamides include polyhexamethylene adipamide (Nylon 66),
polyhexamethylene azelaamide (Nylon 69), polyhexamethylene sebacamide
(Nylon 610), and polyhexamethylene dodecanoamide (612 Nylon), the
polyamide produced by ring opening of lactams, i.e., polycaprolactam,
polylauric lactam, poly-11-aminoundecanoic acid, bis(paraaminocyclohexyl)
methane dodecanoamide. It is also possible to use in this invention
polyamides prepared by the copolymerization of two of the above polymers or
terpolymerization of the above polymers or their components, e.g., 6T/DT, a
copolymer of terephthalic acid (T) and 2-methylpentamethylenediamine (D)
20 and hexamethylenediamine (6). Preferably the polyamides are semi-
crystalline and aliphatic or semi-aromatic with a melting point in excess of
200~C, or they are amorphous.
Preferred polyamides include Nylon 66, Nylon 6, Nylon 612, Nylon 11,
Nylon 12, Nylon 1212, amorphous nylons, Nylon 6/66 copolymers.
Most preferred polyamides include Nylon 66, Nylon 612 and Nylon 6.
It is to be understood that this component may comprise blends of two
or more nylons.
COMPONENT jj) The polyamides used in component ii) are best described
as low temperature polyamides. Typically, they are prepared from
(a) at least one dicarboxylic acid and at least one diamine, wherein
said dicarboxylic acid or said diamine or both contain at least one alkyl branchhaving one to three carbon atoms; and wherein said dicarboxylic acid or said
AM~ED SllE~T
_
- CA 02248l23 l998-09-02
. . . .
_,
diamine or both comprise at least seven methylene groups; or
(b) at least one alpha, omega aminocarboxylic acid, having the
formula of H2N-R(1 )-COOH, in which R(1) is an aliphatic moiety having at
least six methylene groups and at least one pendant alkyl branch having 1 to
5 3 carbon atoms, or
(c) at least one diamine and at least one nitrile selected from the
group consisting of alpha omega amino alkylene nitriles and alpha omega
alkylene dinitriles, wherein said diamine or said nitrile or both contain at least
one alkyl branch having one to three carbon atoms; and wherein said diamine
0 or said nitrile or both comprise at least seven methylene groups; or
(d) mixtures of any of the monomers described in (a)-(c) above.
Examples of the diamines include 1,6 hexamethylene diamine; 1,8
octamethylene diamine; 1,10 decamethylene diamine and 1,12-
dodecamethylene diamine. Examples of a branched diamine include 2-
5 methyl-pentamethylene diamine, but other branched diamines having C1-C3
alkyl branches may be used.
Examples of the dicarboxylic acids include 1 ,6-hexanedioic acid (adipic
acid); 1,7-heptanedioic acid (pimelic acid); 1,8-octanedioic acid (suberic acid);
1 ,9-nonanedioic acid (azelaic acid); 1,1 0-decanedioic
20 acid (sebacic acid) and 1,12-dodecanedioic acid. Examples of branched
dicarboxylic acids include 2-methyl glutaric acid, but other branched
dicarboxylic acids having C1-C3 alkyl branches may be used.
D12 is a homopolymer of 2-methylpentamethylene diamine and
dodecanedioic acid. The copolymer of D12/612 is a copolymer of 2-
25 methylpentamethylene diamine, hexamethylene diamine and dodecanedioicacid. These represent preferred nylon choices. Examples of alpha, omega
amino carboxylic acids are aminocaproic acid, amino octanoic acid, amino
decanoic acid, amino undecanoic acid and aminododecanoic acid. It should
be noted that the aminocarboxylic acid may be in the form of a lactam,
30 especially when the aliphatic moiety has six methylene groups. Examples of
branched alpha, omega amino carboxylic acids are 2-methyl-amino
dodecanoic acid and 2-methyl-amino decanoic acid although others may be
used.
18
~1 S~EEt
CA 02248123 1998-09-02
_ _ , ,, , t , _,, . . .
t ~ _ ,, ~ ~ , . . . .. .
Examples of the nitriles are 1,5 aminocapronitrile, adiponitrile, 1,11-
amino undecanonitrile, 1,10-amino decanodinitrile and 2-methyl-1,11-amino
undecanonitrile although others may be used.
In addition to monomers (a)-(c) listed herein, other monomers may be
5 used to prepare the polyamides of the present invention. These other
monomers include, but are not limited to, aromatic dicarboxylic acids,
aromatic diamines, alicyclic dicarboxylic acids, and alicyclic diamines.
Examples of aromatic dicarboxylic acids include terephthalic and isophthalic
acids. An example of an alicyclic dicarboxylic acid is 1,4-bismethylene
0 cyclohexyl dicarboxylic acid. An example of an alicyclic diamine is 1,4-
bismethylene diamino cyclohexane. When the polyamide is semi-crystalline,
it is desirable that such polyamide exhibit a melting point less than 200~C and
a broad melting profile, which is herein defined as the range of temperature
from the onset of the melting curve in a differential scanning calorimetry
5 (DSC) test to the maximum melting peak that is measured, of greater than
about 45~C.
The polyamides may be manufactured using processes well known in
the art. In particular the polyamides may be polymerized from salts of the
diamine and dicarboxylic acid. Alternatively, the polyamides may be
polymerized using the corresponding nitriles, as discussed above.
The polyamide may be in the form of a homopolymer polymerized from
one diamine and one dicarboxylic acid, an aminocarboxylic acid, an amino
alkyl nitrile, or one diamine and a dinitrile. Alternatively, the polyamide may
be a copolymer polymerized from at least one diamine with more than one
25 dicarboxylic acid or at least one dicarboxylic acid with more than one diamine
or a combination of at least one diamine, at least one dicarboxylic acid and at
least one aminocarboxylic acid, optionally containing nitriles. The copolymer
preferably contains at least about 20 mole percent of branched moieties, more
preferably at least about 30 mole percent and most preferably at least about
30 50 mole percent of branched moieties, based on the total amount of the
aliphatic moieties in the polyamide.
In preferred embodiments of the present invention, the polyamide,
St3EEr
_ .
CA 02248123 1998-09~-02 , ~ c ~r ~r
r '' ~ ' _ ~ r
_,, ' r - r ~ ~ ~ _,,
when semi-crystalline, has a melting point of less than 200~C, more preferably
between about 120~C to about 180~C, and most preferably between about
140~C to about 180~C. It is also preferred thatthe polyamide has a broad
melting profile of greater than about 45~C, preferably greater than about 50~C,
and most preferably greater than about 55~C.
COMPONENT jjj) Suitable ethylene copolymers include ethylene/acrylic
acid, ethylene/methacrylic acid, ethylene/acrylic acid/n-butyl acrylate,
ethylene/methacrylic acid/n-butyl acrylate, ethylene/methacrylic acid/iso-butyl
acrylate, ethylene/acrylic acid/iso-butyl acrylate, ethylene/methacrylic acid/n-0 butyl methacrylate, ethylene/acrylic acid/methyl methacrylate, ethylene/acrylic
acid/ethyl vinyl ether, ethylene/methacrylic acid/butyl vinyl ether
ethylene/acrylic acid/-methyl acrylate, ethylene/methacrylic acid/methyl
acrylate, ethylene/methacrylic acid/methyl methacrylate, ethylene/acrylic
acid/n-butyl methacrylate, ethylene/methacrylic acid/ethyl vinyl ether and
ethylene/acrylic acid/butyl vinyl ether.
Preferred ethylene copolymers that contain a monocarboxylic acid
moiety for use in the compositions of the present invention include
ethylene/methacrylic acid, ethylene/acrylic acid, ethylene/methacrylic acid/n-
butyl acrylate, ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylic
20 acid/methylacrylate and ethylene/acrylic acid/methylacrylate copolymers. The
most preferred ethylene copolymers for use in the compositions of the present
invention are ethylene/methacrylic acid, ethylene/acrylic acid copolymers,
ethylene/methacrylic acid/n-butyl acrylate and ethylene/methacrylic
acid/methylacrylate terpolymers.
Surlyn~ is an example of a suitable commercially available product.
Zinc-neutralized Surlyn~ is preferred for nylor; over sodium-neutralized
Surlyn~.
COMPONENT jV) These polymeric grafting agents include ethylene
copolymers copolymerized with monomers containing one or more reactive
30 moieties said monomers selected from unsaturated epoxides of 4-11 carbon
atoms, such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether,
vinyl glycidyl ether, and glycidyl itaconate, unsaturated isocyanates of 2-11
Afl~NE)E~
, . ,~ . ~ - .
.
CA 02248123 1998-09-02
<~ r r ,~
carbon atoms, such as vinyl isocyanate and isocyanato-ethyl methylacrylate,
aziridine and monomers containing, silanes such as alkoxy or alkyl silanes,
alkylating agents such as alkyl halides, or alpha-halo ketones or aldehydes or
oxazoline, and the polymeric grafting agent may additionally contain an alkyl
5 acrylate, alkyl methacrylate, carbon monoxide, sulfur dioxide and/or alkyl vinyl
ether, where the alkyl groups contain 1-12 carbon atoms.
Preferred polymeric grafting agents for use in the compositions of the
present invention include ethylene/glycidyl acrylate, ethylene/n-butyl
acrylate/glycidyl acrylate, ethylene/methylacrylate/glycidyl acrylate,
10 ethylene/glycidyl methacrylate, ethylene/n-butyl acrylate/glycidyl methacrylate
and ethylene/methylacrylate/glycidyl methacrylate copolymers. The most
preferred grafting agents for use in the compositions of the present invention
are copolymers derived from ethylene/n-butyl acrylate/glycidyl methacrylate
and ethylene/glycidyl methacrylate.
It should be noted that the level of reactive component e.g. glycidyl
methacrylate will affect the degree of crosslinking with the nylon, and may be
adjusted appropriately to the desired level as known by those skilled in the art.
COMPONENT V) The graft monomers, and mixtures thereof, used to
prepare the graft polymers can be selected from the group consisting of
20 ethylenically unsaturated acidic monomers or their derivatives including
acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic
acid, 5-norbornene-2,3-dicarboxylic acid, maleic anhydride, monosodium
maleate, disodium maleate, itaconic anhydride, citraconic anhydride,
monomethyl fumarate and monomethyl maleate. Also, the graft monomers
25 can be selected from ethylenically unsaturated monomers containing amino or
hydroxy functional groups including vinyl pyridines, vinyl silanes, 4-vinyl
pyridine, vinyltriethoxysilane and allyl alcohol. The grafting monomers, and
mixtures thereof, can be present in the graft polymer in an amount of from
0.05 to 5% wt. and would be grafted onto a C2-C20 polyolefin including
30 polyethylene, polypropylene, ethylene propylene diene terpolymer, as well as
copolymers of ethylene with, but not limited to, vinyl acetate, carbon
monoxide, or ethylenically unsaturated carboxylic acids or esters thereof.
This component acts as an alternative toughener in the formulation.
2 1
N~ED SHEEt
.
CA 02248123 1998-09-02
. . r r C ~ r r .
; , _ r ~ ~ ,, . r ~ ~ '
Grafted polyethylene, grafted polypropylene, and grafted rubber, may be used
as noted earlier, and these may be used in combination with non-grafted
polyethylenes, polypropylenes and rubbers. This component may be used
interchangeably with component iii) in Formulations C and D as noted before
5 in this disclosure.
FILM FORMATION The heat-sealable polyamide film may be formed by a
cast film process or by a blown film process. Both types of film processes are
known in the art of manufacture of polyamide films. Furthermore, the film may
be a monolayer film or a multilayer film, the film being for example a
0 coextruded film or a laminate. Either the monolayer film or the coextruded
film may be in an unoriented condition, in the form of monoaxially oriented filmor in the form of biaxially oriented film. It will be understood by persons skilled
in the art that the properties of such polyamide films will depend on several
factors including, but not limited to, extruder hold-up time and screw design,
melt processing temperature, quenching rate and degree of quenching, film
thickness, the amount of and type of additional components, as well as the
amount of and type of the particular polyamide as described herein.
The polyamide resins described herein may also be coextruded or
laminated with polyolefins or grafted polyolefin, particularly polyethylene,
grafted polyethylene or grafted polypropylene, especially using tie or adhesive
layers between the polyamide and polyolefin. The heat-sealable polyamide
films may be laminated to polyolefins or other barrier polymers using
conventional processes. In addition, the heat-sealable polyamides may be
coated with polyvinylene dichloride (PVDC), EVOH, PVOH or other suitable
25 barrier coatings and then laminated to itself to form a higher barrier heat-
sealable structure.
BLENDING OF FORMULATION COMPONENT The compositions of the present
invention, especially when in the form of layers e.g. films or sheets, may be
treated with a corona discharge (ED) in order to improve the properties of the
resins with respect to bonding of coatings, inks, adhesives or the like. In
addition, the resins may contain additives such as, but not limited to,
moisturizing agents, heat stabilizers, flame retardants, fillers, anti-blocking
agents, slip additives, pigments or dyes, processing aids, anti-oxidants,
22
.. . =
~_
CA 02248123 1998-09-02 ,~ ..
r c; r r c c; . ~ .
t ~ S ~. c , .~
plasticizers or ultra violet blocking agents. The components described above
are melt blended with each other under high shear. The various ingredients
may first be combined with one another in what is commonly referred to as a
"salt and pepper" blend, i.e., a pellet blend, of each of the ingredients, or they
5 may be combined with one another via simultaneous or separate metering of
the various components, or they may be divided and blended in one or more
passes into one or more sections of mixing equipment such as an extruder,
Banbury, Buess Kneader, Ferrell continuous mixer, or other mixing
equipment. For example, one can use an extruder with two or more feed
10 zones into which one or more of the ingredients may be added sequentially.
In this case, it is sometimes advantageous that the thermoplastic and
polymeric grafting component be combined first, then the acid-containing
copolymer be added downstream. This helps promote the grafting reaction(s)
between the thermoplastic and polymeric grafting components, prior to the
15 reaction(s) between the polymeric grafting component and acid-containing
copolymer. However, the order of addition is such that the components (iii)
and (iv) would never be added to the extruder without the nylon, as otherwise,
a crosslinked non-extrudable material would result. The high shear insures
proper dispersion of all the components such as would be necessary to carry
out the grafting reaction. In addition, sufficient mixing is essential to achieve
the morphology which is necessary in the compositions of the present
invention. The morphology required for the compositions of the present
invention is that at least one of continuous phases must be the thermoplastic,
i.e., component i)., optionally also ii). Note that the thermoplastic, component25 i., optionally ii)., is at least one of the continuous phases in all of the
compositions of the present invention even though the thermoplastic,
component i)., optionally ii)., comprises less, and in fact, in many cases
substantially less than 50 volume %. The addition of polyamides (a) and (b)
forms one phase, so the combined polyamide phase should be preferred as
30 the continuous phase.
In the following examples, there are described embodiments of the
invention, which are for illustrative purposes only. These should not be used
to limit the scope of the appended claims.
23
r' ~
CA 02248l23 l998-09-02
~ r
- r .
,. . . C ~ r . C ~,
Examples
1. Test Methods:
1.1. Bubble Formabiiity:
A skin packaging machine made by Sergeant, called a 1218 Packsafe,
was modified to allow for evaluation of bubble formability. A metal perforated
plate was installed on the surface of the skin-packaging base, allowing the
vacuum holes to pull heated film into these perforations. The perforated metal
sheet is 45.7 cm (18 inches) by 30.5 cm (12 inches) by 0.48 cm (3/16 inches)
deep. The holes are 0.95 cm (3/8 inches) in diameter, and are staggered at
0 60 degree angles. The holes are spaced 1.43 cm (9/16 inch) apart, center to center.
The three variable cycle settings on the Packsafe machine are the
"preheat", "heat-hold" and "vacuum" cycles. The film is placed in a moveable
frame and raised to about 6.35 cm (2.5 inches) away from a series of
overhead IR heaters. During the period known as the "preheat", the film is
heated by IR wires for a given period of time. Then the cage is lowered onto
the perforated plate as vacuum is being drawn through the holes in the
perforated plate. This period is known as the "heat-hold". Finally, the heated
film is pulled into the holes in the perforated plate by the applied vacuum for a
given period of time (IR heaters now turned off) called the "vacuum cycle".
In addition, the amount of vacuum drawn through the holes in the
perforated plate can also be altered, going from about 20 mm Hg up to 140
mm Hg.
The ability of the film to form bubbles is rated on a scale of 0 to 4:
0 = no forming of film into the cavity of the perforated plate
1 = shallow forming of film into cavity
2 = intermediate forming of film into cavity
3 = partial deep forming of film into cavity--part of the film has bottomed out on
the floor of the cavity hole
4 = complete deep forming of film into cavity--the entire floor of the formed film
has bottomed out onto the floor of the cavity hole, and impressions of the
vacuum holes are present.
Each bubble was individually rated, then the ratings were averaged for
24
. ~ .
, : =. ..
AA~NDED SHEEr
~ ... . ..
CA 02248123 1998-09-02 . ~ ,~ t.
,. , _ .. , . :
. .
.
each film surface evaluated.
1.2. Heat-Sealability (self-adhesion):
~ The heat seals were obtained using a Sentinal Model 12 ASL/1 heat
sealer, using the following conditions:
* 1/4 second dwell time
* 1/8-inch (0.3175 cm) seai barwidth
* only upper jaw heated (continuous heating)
* 275.8 KPa (40 psi) jaw pressure
The temperature during heat-sealing was measured by the
0 thermocouple embedded in the upper jaw, and thus is referred to as "jaw
temperature".
Three pre-heat cycles (jaw closures) were done to pre-heat the lower
jaw prior to the heat seal test. The heat sealed samples were cut having a
width of 1.0 inches (2.54 cm), and tested on an Instron (Model 4204) having a
crosshead speed of 20 inches (50.8 cm) per minute and having a grip
distance of 2 inches (5.08 cm).
It is understood that heat seal and hot tack can be measured on any
commercially available heat-sealer. In the determination of minimum heat-
seal temperatures described herein; the minimum heat seal strength
measurable on the apparatus used was about 30 g/cm. It is also understood
that the actual temperature at the heat-seal interface will be lower than the
actual temperature, the difference depending on the heat-seal conditions and
the type of heat-seal machine used.
1.3. Thermal Stability:
Thermal stability is measured by placing the film under test in a hot-air
oven, and heating the film for one hour at 200-deg C. A visual and manual
inspection of the film was done after the oven heating to see if the film had
melting or become embrittled.
- EXAMPLES
EXAMPLE 1:
Pellets of Zytel FN~ 726 were melt extruded in a 2.54 cm Killion single
screw extruder, having an L/D of 24:1, at a melt processing temperature of
233 to 239 deg C using a 120/60/80 rnesh filter pack. The extrudate was
~ED SHEFr - --------
.
CA 02248123 1998-09-02 - _,
extruded through a 5cm diameter spiral blown film die having a die gap of
0.076cm (30 mils).
~ Bubble formability, heat-sealability and thermal stability tests were
conducted on these films. In addition, a commercially available LLDPE film,
5 SCLAIR(~9 A693, having a thickness of 51 microns, was also tested. A
commercially available Nylon 6 film, having an RV (in formic acid) of about 70
and a thickness of 56 microns, was also tested. The results of bubble
formability are shown in Table Vll, and those of heat-sealability and thermal
stability in Table Vlll:
26
~E~ ~Fr
.. , _ _ . _ .. _ _ _ .. ........ .
CA 02248123 1998-09-02
_.. r r r; r r L r _
TABLE Vll
Film Type Effective vacuum Preheattime, Bubble Formability
level, mm Hg seconds (scale 0 to 4)
Zytel FN~ (SampleA) 20 2.4 1.0
19.7 4.0
11.2 4.0
140 2.4 1.0
140 19.7 4.0
Zytel FN~) (Sample B) 20 2.4 1.0
11.2 4.0
19.7 4.0
140 2.4 1.0
140 19.7 4.0
LLDPE 20 2.4 0
19.7 4.0
11.2 3.0
140 2.4 0
140 19.7 4.0
Nylon 6 20 2.4 0
19.7 1.2
11.2 0
140 2.4 0
140 19.7 1.0
Note: the following cycle-time settings on the Packsafe machine were used:
Preheat Dial: 2.4 seconds = 0 dial setting
11.2 seconds = 95 dial setting
~~ 19.7 seconds= 200 dial setting
Heat-Hold Dial: 60 dial setting
Vacuum Dial:2 seconds = 60 dial setting
It is assumed that the minimum acceptable bubble formability is 3.
From the above, it can be seen that the Zytel FN~3) films have bubble
10 formability characteristics similar to LLDPE, and that both pass this formability
criteria. The Nylon 6 cannot form good bubbles.
. . . _
.
CA 02248123 1998-09-02
_ . . r ~ r r ~ . -
Table Vlll
Film Type HeatSeal Temp. (C) at Heat Seal Film afteroven heataging
Initiation max. heat maximum
Temp. (C) seal strength strength (KPa)
Zytel FN~ 200 240 207 Film retains good
toughness
LLDPE 140 180 172 Melted
Nylon 6 230 260 255 Film brittle (not heat-
~l~bili~ed)
It can be seen that Zytel FN~ film starts to heat-seal at a lower temperature
than Nylon 6, and it also has a wider heat-sealing window.
EXAMPLE 2:
"Salt and Pepper" blends (a dry pellet mixture) of various compositions
were melt extruded in a 2.0 cm Welding Engineers twin-screw extruder, with
non-intermeshing, counter-rotating screws, having an L/D of about 60. The
melt was processed at one of 240~C, 260~C or 280~C using a 125 micron
filter screen. A vacuum was applied to the vent port. The melt was extruded
0 through a 15cm flat film die having a die gap of 0.064cm (25 mils). The
extrudate was quenched on a chill roll set at a temperature of 30~C to form a
film having a thickness of about 51 microns. Bubble formability, heat-
sealability and thermal stability tests were conducted on these films. In
addition, comparison films made from Nylon 6 (BASF BS700A Nylon 6, with
50 RV) and Nylon 66 (50 RV in formic acid) were made. A commercially
available Nylon 6 film, having an RV (in formic acid) of about 70 and a
thickness of 56 microns, and a commercially available LLDPE film, SCLAIR~
A693, having a thickness of 51 microns, were also tested for comparative
purposes. The following blends as set out in Table IX were made into film:
Table IX
BlendA Zytei FN~727 (100 % wt.)
Blend B Zytel FN~ 727//Nylon 6 (751125 blend ratio)
Blend C Zytel FNW 727//Nylon 6 (50//50 blend ratio)
Blend D Nylon 611g-PEllSurlyn~ 9320 (601151135 ratio)
Blend E Nylon 611g-PEllSurlyn~ 9520 (601151135 ratio)
Blend F Nylon 6//Surlyn~ 9520 (60//40 blend ratio)
Comparative Film G Nylon 6 (BASF BS700 A)
Note: the Zytel FN~' 727 and Blend D contain anti-oxidants and are heat-
stabilized. However, none of the other components have been heat-
28
CA 02248123 1998-09-02
stabilized, so the thermal stability tests are only useful for indicating whether
the film would melt or not when placed in the oven for one hour at 200~C.
~ The results of bubble formability are given in Table X, while those of
heat-sealability and oven heat-resistance are given in Table Xl.
TABLE X
Film Type Melt Processing Temp., Bubble For",~ (scale 0 to
C 4)
Blend A 240 4.0
Blend B 240 3.9
Blend D 240 4.0
Blend E 240 4.0
Blend F 240 4.0
Comp. Blend G 240 2.0
BlendA 260 4.0
Blend B 280 4.0
Blend C 280 3.8
Blend D 280 4.0
Comp. Blend G 280 1.0
Nylon 6 commercial 2.4
film
LLDPE 4.0
Note: the cycle-time settings on the Paccsafe machine were as follows:
Preheat time: 11 seconds = 95 on the dial
Heat-hold: 1.3-1.4 seconds = 60 dial setting
- Vacuum: 0.65-0.75 seconds = 20 dial setting, effective vacuum
level = 120-130 mm Hg.
The minimum acceptable bubble rating is assumed to be 3. Using this
criteria, the claimed blends all pass the forming criteria, as does the LLDPE
film, while both the comparative Nylon 6 film and the commercially available
Nylon 6 film do not pass this criteria.
TABLE Xl
Film Type Heat Seal Temp. (C) at max. Heat Seal Film afterInitiation heat seal strength maximum strength oven heat
Temp. (C) (KPa) aging
Blend A 270 290 12,770 Pass
Blend B 250 270 12,942
Blend D 260 300 15,783 Pass
Blend F 250 270 2600 Did not melt
LLDPE 160 200-240 11,239 Melted
Capran N6 250 280 11,087 Did not melt
29
:- ~I~~D St1~E~
.,
CA 02248123 1998-09-02 - ~ -
It can be seen that the claimed blends are heat-sealable, and pass the oven
test without melting, while LLDPE melted.
EXAMPLE 3
A "salt and pepper", or dry blend, of the following composition was
prepared.
Nylon 6 (BASF BS700A): 29.8 % wt
D12 (RV = 50): 29.8 %
Surlyn~): 30.0 %
Ethylene/N-Butyl Acrylate/Glycidyl Methacrylate (Elvalloya~): 10.0 %
10 Anti-oxidant (Cul/KI/Alum. Distearate 7:1:0.5): 0.48 %
Also, as a control, Zytel FN~' 727 was also used, which is a partially
grafted, multi-phase flexible thermoplastic composition.
The above two formulations were each separately melt extruded in a
53 mm W&P twin screw extruder at a melt processing temperature of 245~C
and using a 125 micron filter. The melt was extruded through a 122cm flat
film die. The extrudate was quenched on a chill roll set at a temperature of
31 ~C to form a film having a thickness of 53 microns.
In the dry blend, the Nylon 6 component has a relative viscosity (in
formic acid) of 50, while the D12 polymer has a relative viscosity (in formic
20 acid) of 50.
A control for bubble formability and heat stability was also tested, which
is a commercially available polyethylene/Nylon6/polyethylene coextrusion, this
structure being 51 microns thick with the Nylon core layer being 5 microns
thick.
Heat-seal, bubble formability and heat stability tests were carried out
on these films. The results are as shown in Table Xll.
3 SHEET
.
CA 02248123 1998-09-02
, .,
Table Xll
Test Dry Blend~ Zytel FN w Coex Control
Heat~ealability:
Seal Initiation Temp. (Jaw ~ 200 ~C 240 ~C
temp.) ~C
Maximum Seal Temp. (Jaw 260-280 ~C 260-280 ~C
Temp.) ~C
Maximum bond strength, g/in 2909 2454
Bubble Formability (using Excellent Excellent Excellent
modifled Packsafe Skin
Packaging machine)
Heat Stability Test (one hour in
hot air oven at 200 ~C):
% ClongdLion before heat-aging: 438 382 394
% Elongation afterheat-aging: 253 374 3
Ultimate Tensile Stress before 50,975 38,005 31,483
heat-aging (KPa)
UltimateTensile Stress after 29,835 38,440 6688
heat-aging: (KPa)
* Dry pellet mixture
One can see that both the "salt and pepper" blend (dry pellet blend) and the
5 Zytel FN~ formulation have good heat-sealability, formability and oven
stability. The dry blend, containing the D12 polyamide, has a lower heat-seal
initiation temperature and a higher maximum bond strength than the Zytel FNQ
formulation. Both retain their film physical properties to a much greater extentthan the poly/Nylon/poly coextrusion.
1 O HEAT-SEALABILITY:
Seal barwidth = 1/8 inch (0.3175 cm)
Jaw Sealing Pressure = 40 psi (276 KPa)
Seal Dwell time - 1/4 second
BUBBLE FORMABILITY:
15 Film Preheat time = 11 seconds (potentiometer setting=95)
Heat Hold = 1.4 seconds. Time between end of preheat and end of heating
cycle. (potentiometer setting=60)
Effective vacuum time = 0.7 seconds (potentiometer setting=20)
HEAT STABILITY:
20 Recirculating Hot Air Oven, set at 200 deg C
CA 02248123 1998-09-02 - ,
Sample films sandwiched between Teflon-coated polyester and placed in
oven for one hour.
Film tensile properties measured using ASTM D 882-91.
The above two formulations were made into bubble-pack structures
5 using a commercial process. The bubble pack structures were then placed in
a recirculating hot air oven for one hour at 200~C. For both formulations, the
bubbles retained their shape after oven heating, i.e. the bubbles did not
collapse.
The foregoing is considered to be illustrative only of the principles of
10 the invention. Further, since numerous modifications and changes will occur
to those skilled in the art, it is not desired to limit the invention to the exact
construction and operation shown and described, and, accordingly, all
suitable modifications and equivalents may be resorted to, falling within the
scope of the invention.
~~1iltJ~D SHEEr - : - -
. . . . = . . .
