CA1268409A - Multiple layer sheet materials - Google Patents
Multiple layer sheet materialsInfo
- Publication number
- CA1268409A CA1268409A CA000505643A CA505643A CA1268409A CA 1268409 A CA1268409 A CA 1268409A CA 000505643 A CA000505643 A CA 000505643A CA 505643 A CA505643 A CA 505643A CA 1268409 A CA1268409 A CA 1268409A
- Authority
- CA
- Canada
- Prior art keywords
- layer
- sheet material
- layers
- material according
- composition
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Laminated Bodies (AREA)
- Wrappers (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention is in an improved multiple layer packaging sheet material which can be formed into closed and sealed packages suitable for holding products containing substantial fractions of cyanoacrylate. The invention depends on the positioning of high density polyethylene in direct contact with the cyanoacrylate-type product, and positioning a primer on the other side of the high density polyethylene. Preferred embodiments of the sheet structure include additional layers to provide barrier and abuse resistance properties, and the necessary adhesive materials to hold the various layers of the structure together with good adhesion. Additional layers are contemplated. The sheet structure can be formed into a package which positions the high density polyethylene adjacent the cyanoacrylate product, and between it and the other layers at all locations of contact between the cyanoacrylate product and the packaging sheet material.
The invention is in an improved multiple layer packaging sheet material which can be formed into closed and sealed packages suitable for holding products containing substantial fractions of cyanoacrylate. The invention depends on the positioning of high density polyethylene in direct contact with the cyanoacrylate-type product, and positioning a primer on the other side of the high density polyethylene. Preferred embodiments of the sheet structure include additional layers to provide barrier and abuse resistance properties, and the necessary adhesive materials to hold the various layers of the structure together with good adhesion. Additional layers are contemplated. The sheet structure can be formed into a package which positions the high density polyethylene adjacent the cyanoacrylate product, and between it and the other layers at all locations of contact between the cyanoacrylate product and the packaging sheet material.
Description
1;~;~3409 The present invention relates to an improved multiple layer packaging sheet material which can be formed into closed and sealed packages suitable for holding products containing substantial fractions of cyanoacrylate.
Products containing cyanoacrylate are quite active chemically. Because of the reactive nature of cyanoacrylates, it has been difficult to find packagin~ means and material with which the cyanoacrylate product does not interact in a way which is detrimental to the cyanoacrylate in the package, and to u holding it in the package.
Traditionally, cyanoacrylate adhesives have been packaged in plastic bottles and metal tubes. The plastic containers do not provide adequate vapor barrier, such that the 1~ shelf-life of products packaged in conventional plastic containers is undesirably short. Metal tubes also have some undesirable characteristics. They are relatively inflexible such that they can be flexed only a few times as in repeated dispensing before cracks develop in the tube sidewall. Overall, 2U though, shelf life of cyanoacrylate products is better in metal tubes than plastic, at least untll the tube is initially opened.
nevertheless, the shelf life, even in metal tubes, is less than desired~ Clearly, cyanoacrylates are readily identified as being difficult to hold in a package over a desirable shelf life
Products containing cyanoacrylate are quite active chemically. Because of the reactive nature of cyanoacrylates, it has been difficult to find packagin~ means and material with which the cyanoacrylate product does not interact in a way which is detrimental to the cyanoacrylate in the package, and to u holding it in the package.
Traditionally, cyanoacrylate adhesives have been packaged in plastic bottles and metal tubes. The plastic containers do not provide adequate vapor barrier, such that the 1~ shelf-life of products packaged in conventional plastic containers is undesirably short. Metal tubes also have some undesirable characteristics. They are relatively inflexible such that they can be flexed only a few times as in repeated dispensing before cracks develop in the tube sidewall. Overall, 2U though, shelf life of cyanoacrylate products is better in metal tubes than plastic, at least untll the tube is initially opened.
nevertheless, the shelf life, even in metal tubes, is less than desired~ Clearly, cyanoacrylates are readily identified as being difficult to hold in a package over a desirable shelf life
2~ period.
Products have been packaged in tube-type containers of generally three types. The first type is a metal tube. Such tubes provide excellent barrier properties, but have undesirable functional properties as discussed above. The second type is a plastic tube made from either single or multiple layers of plastics. While plastic tubes may be excellent for many products, no plastic packaging materials are known which are excellent for holcling cyanoacrylate-type products. The third type is a tube macle from previously formed multiple layer sheet ~, ....
. .
- . ~
~2684(~
materials containin~ a layer of metal foil and a plurality of layers of plastic materials, generally re~erred to hereinafter as laminated tubes.
The third type of tube container has been used conventionally for holding hygienic-type products such as toothpaste. Tooth paste is chemically quite active, and is generally considered difficult to hold in a package.
Attempts to package cyanoacrylate adhesives in the u third type of tube containers were not successful with any of the conventionally known sheet materials used t~ make the laminated tubes. After being packaged in conventional tubes of the third type, the cyanoacrylate adhesive migrated through polymer layers to the foil layer. The tube delaminated between the foil layer 1~ and the ad~acent polymer layer. The delaminated tube was not satisfactory for the package.
Cyanoacrylate also tends to cause swelling or polymers.
In trials with some experimental multiple layer tubes, polymer 2U layers disappeared as distinct layers, presumably having been either dissolved into the cyanoacrylate or otherwise ab~orbed into it.
The present invention provides a packaging sheet 21 material capable of holding cyanoacrylate-type products.
The present invention also provides such a sheet material which has excellent barrier to passage of matter through the sheet material.
3U The invention again provides a package capable of holding a cyanoacrylate-type product.
According t~ the present invention there is provided a multiple layer sheet material having all the layers firmly ~` 1, , .
:: . . . .
: :.... .. . .
" ., : .
- . .... .
~68flC~9 adhered to each other. The sheet material has a first layer of high density polyethylene (HDPE), a second layer which may be a polymer or an adheslve, and a third primer layer of polyethylene imine ( PEI ) . The third primer layer is between the first and second layers.
Regarding the layer compositions, each of the layers has preferred features which, while not critical to the invention, contribute to its efficiency or optimization. Thus, the resin density of the HDPE as determined by ASTM D-2839 is preferably at least 0.950. It should also preferably have a u narrow molecular weight distribution and should be substantially free of amine components. Preferably it crystallinity is relatively high as developed in formation of that film~like layer.
The second layer may be any of a wide variety of functional materials which exhibit the desired properties.
Preferred for the second layer is ethylene acrylic acid copolymer ~EAA) .
2~
The primer in the third layer is preferably applied as a liquid solution containing a cross-linking type PEI.
Preferred embodiments of the sheet material include a fourth layer of metal foil so positioned in the structure that 2~ the second layer is between the third and fourth layers.
Finally, in most preferred embodiments, a flfth layer adhered a sixth layer, as of polyethylene, to the metal foil.
Products have been packaged in tube-type containers of generally three types. The first type is a metal tube. Such tubes provide excellent barrier properties, but have undesirable functional properties as discussed above. The second type is a plastic tube made from either single or multiple layers of plastics. While plastic tubes may be excellent for many products, no plastic packaging materials are known which are excellent for holcling cyanoacrylate-type products. The third type is a tube macle from previously formed multiple layer sheet ~, ....
. .
- . ~
~2684(~
materials containin~ a layer of metal foil and a plurality of layers of plastic materials, generally re~erred to hereinafter as laminated tubes.
The third type of tube container has been used conventionally for holding hygienic-type products such as toothpaste. Tooth paste is chemically quite active, and is generally considered difficult to hold in a package.
Attempts to package cyanoacrylate adhesives in the u third type of tube containers were not successful with any of the conventionally known sheet materials used t~ make the laminated tubes. After being packaged in conventional tubes of the third type, the cyanoacrylate adhesive migrated through polymer layers to the foil layer. The tube delaminated between the foil layer 1~ and the ad~acent polymer layer. The delaminated tube was not satisfactory for the package.
Cyanoacrylate also tends to cause swelling or polymers.
In trials with some experimental multiple layer tubes, polymer 2U layers disappeared as distinct layers, presumably having been either dissolved into the cyanoacrylate or otherwise ab~orbed into it.
The present invention provides a packaging sheet 21 material capable of holding cyanoacrylate-type products.
The present invention also provides such a sheet material which has excellent barrier to passage of matter through the sheet material.
3U The invention again provides a package capable of holding a cyanoacrylate-type product.
According t~ the present invention there is provided a multiple layer sheet material having all the layers firmly ~` 1, , .
:: . . . .
: :.... .. . .
" ., : .
- . .... .
~68flC~9 adhered to each other. The sheet material has a first layer of high density polyethylene (HDPE), a second layer which may be a polymer or an adheslve, and a third primer layer of polyethylene imine ( PEI ) . The third primer layer is between the first and second layers.
Regarding the layer compositions, each of the layers has preferred features which, while not critical to the invention, contribute to its efficiency or optimization. Thus, the resin density of the HDPE as determined by ASTM D-2839 is preferably at least 0.950. It should also preferably have a u narrow molecular weight distribution and should be substantially free of amine components. Preferably it crystallinity is relatively high as developed in formation of that film~like layer.
The second layer may be any of a wide variety of functional materials which exhibit the desired properties.
Preferred for the second layer is ethylene acrylic acid copolymer ~EAA) .
2~
The primer in the third layer is preferably applied as a liquid solution containing a cross-linking type PEI.
Preferred embodiments of the sheet material include a fourth layer of metal foil so positioned in the structure that 2~ the second layer is between the third and fourth layers.
Finally, in most preferred embodiments, a flfth layer adhered a sixth layer, as of polyethylene, to the metal foil.
3~ Another aspect of the invention is seen in a package which includes the novel packaging sheet material herein ln the form of a package and a quantity of product therein where the product contains cl substantial fraction of a cyanoacrylate-type component. The package is configured such that no edge of the ; .
-.. . .
:.
,:
126~3409 sheet material is exposed to the product.
Thus according to one aspect thereof the presentinvention provides a multiple layer sheet material, including:
(a) a first layer of high density polyethylene; tb) a second layer, the composition of said second layer being chosen from the group consisting of polymers and adheives; and (c) a third primer layer, the composition of said primer layer ha~ing been made from a primer comprising a ma~or fraction of a Lewis base and components of a cyanoacrylate material, said third layer being between said first and second layers.
:l.U
In a further aspect thereof the present invention provides a multiple layer sheet material, including: (a) a first layer of high density polyethylene; (b) a second layer; (c) a third primer layer, the composition of said primer layer comprising a ma~or fraction of a Lewis base, said third primer layer being between said first and second layers; and (d) a fourth layer of metal foil, said second layer bsing between said third and fourth layers.
2U In a still further aspect thereof the invention provides a multiple layer sheet material, comprising: ~a) a first layer of high density polyethylene; (b~ a second layer, the composition of said second layer comprising ethylene acrylic acid ~opolymer; and (c) a third primer layer, the composition of said primer layer comprising a major fraction of a Lewis base; said third layer being adhered in said sheet material to both said first and second layers. Suitably said Lewis base is polyethylene imine.
The present invention again provides a multiple layer sheet material comprising: (a) a first layer of polyethylene having a resin density of at least 0.950, having a narrow molecular weight distribution, and being substantially free of amine compone~ts; (b) a second layer, the composition of said second layer being chosen from the group conslsting of polymers 3~
- ~
. ~
,.
~LX68~0~
and adhesives; and (c) a third primer layer, said third layer including a Lewis base and reacted components from a cyanoacrylate-type material, said third layer being between said first and second layers.
The present invention further provides a multiple layer sheet material comprising, in order: ~a) a first layer of polyethylene having a resin density of at least 0.950, having a narrow molecular weight distribution, and being substantially free of amine components; tb~ a second primer layer of polyethylene imine on one surface of said first layer; (c) a third layer of ethylene acrylic acid copolymer on said second primer layer; and ~d) a fourth layer of metal foil on said third layer.
1~ The invention also provides a multiple layer sheet material including: (a) a first layer of hlgh density polyethylene; (b) a second layer, the composition of said second layer being selected from the group consisting of heat rPsistant polymers and abuse resistant polymers; (c) a third primer layer, 2U the composition of said primer layer comprising a ma~or fraction of a Lewis base, said third layer being between said first and second layers; and (d) a fourth barrier layer bet~een said second and third layers.
The invention also provides a package wherein the packaging sheet material has been modified by virtue of contact with cyanoacrylate-type components. In the modified form of the sheet material, the primer layer includes reacted components from the cyanoacrylate products.
3~
Thus the present invention in another aspect thereof provides a package comprising a packaging sheet material and a product therein, said product including a substantial fraction of cyanoacrylate typ~ component, said packaging sheet material including: (a) a ~irst layer of hlgh density polyethylene; (b) a ' :. : ,, ' ~ 9 second layer, the composltion of said second layer being chosen from the group consisting of polymers and adhesives; and (c) a third primer layer of polyethylene imine, sald third layer being between said first and second layers, said first layer being disposed toward the inside of said package, said package being configured such that no edge of said sheet material is exposed to said product.
The present invention again provides a package comprising a packaging sheet material and a product enclosed therein, said product including a substantial fraction of cyanoacrylate-type component, said packaging sheet material including: (a) a first layer of polyethylene having a resin density of at least 0.950, having a narrow molecular weight distribution, and being substantially free of amine components;
(b) a second layer of ethylene acrylic acid copolymer; (c) a third primer layer, said third layer including polyethylene imine and reacted components from said cyanoacrylate~type product; and (d) a fourth layer of metal foil; said third layer being between said first and second layers, said second layer being between aid 2U third and fourth layers, said first layer being disposed toward the inside of said package, all the layers of said sheet material being adhered to each other, sald package be~ng configured such that no edge of said sheet material is exposed to said product.
The present lnvention will be further illustrated by J way of the accompanying drawings in which:
FIGURE 1 is a cross-section of a three-layer sheet structure of this invention.
3~ FIG~RE 2 is a cross-section of a four-layer sheet structure of this invention.
FIGURE 3 is a cross-section of a six-layer sheet structure of this invention.
: . . .~ , . .
, .. , . - - .: ,~ .:
~ 4 ~
FIGURE 3A is a cross-section of sheet structure not of this invention. It is similar to sheet structure of FIGURE 3, except without the primer layer of FIGURE 3.
FIGURE 3s is a cross-section of another sheet structure not of this invention. It is similar to sheet structure of FIGURE 3 but has the primer layer in the wrong location.
FIGURE 3C is a cross-section of a sheet structure of the invention which has two primer layers.
FIGURE 4 is a pictorial view of an exemplary package of this invention, and including a cyanoacrylate-type product therein.
FIGURE 5 is a greatly enlarged cross-section taken at 5-5 of Figure 4, and showing the primer layers immediately after filling the pac~age with product.
FIGURE 6 ls a greatly enlarged cross-section as in 2U FIGURE 5 shown after a long enough time that the primer layer has been modified and includes reacted components from the product.
In FIGURE 1 is shown a cross-section of a simple sheet structure 110 of the invention, inc'uding two polymeric layers 112 and 116 and a thin primer layer 114 therebetween. Layer 112 2~ is HDPE. The composition of layer 116 is usually polymeric and may be chosen with substantial freedom. Layer 114 is a thin - layer of primer.
In the numbering system, the first digit rep~esents the 3~ FIGURE number. The second and third digits represent the element in the FIGURE. Common second and third digit numbers in the various FIGURES represent common elements. Thus 14 represents the primer layer :ln any of the FIGURES where it is shown. 114 represents the pr:Lmer layer in only FIGURE 1.
"'`' . .
`: .
..
.-"
- .
FIGURE 2 shows a cross-section of a sheet structure 210 of the lnvention of intermediate complexity. Layer 212 is HDPE.
Layer 214 is a thin primer layer. Layer 216 is an adhesive which is effective to adhere to a foil layer 218. with the introduction of the foil layer into the structure, the composition of adhesive layer 216 is selected such that it provides good adhesion between the foil layer 218 and the HDPE
layer 212 through the primer 214. EAA is preferred ~or layer 216.
LU FIGURE 3 shows a cross-section of a sheet structure 310 of the invention having more complexity than the structures of FIGURES 1 and 2, and also having more-preferred functional properties. Layers 312, 314, 316 and 318 are equivalent to the respective ones of those layers in FIGURE 2. Layer 320 is an 1~ adhesive layer which adheres layer 322 to the foil layer 318.
Layer 322 is protective of the foil layer and its composition is selected with that protection property as an important criteria.
As stated earlier, cyanoacrylate is highly xeactive a a 2~ chemical product. it is this strong tendency toward reaction that makes it so difficult to s\design a packaging material to hold it. It is ~urther important that certain layers of the packaging material of this invention not to be permitted to come into direct contact with the cyanoacrylate product. As it has 2~ been found that direct contact with cyanoacrylate can be tolerated by HDPE, it is preferred, and h~ghly functional for the cyanoacrylate-type product to be in direct contact with only the HDPE layer in the flnished packages of this invention. An acceptable package structure is a fin-sealed pouch 411 as seen in 3U FIGURE 4. The peripheral seals 424 are pointed out on 2 of the 4 sides of the pouch.
FIGURE 5 shows a cross-section of the pouch of FIGURE
-.. . .
:.
,:
126~3409 sheet material is exposed to the product.
Thus according to one aspect thereof the presentinvention provides a multiple layer sheet material, including:
(a) a first layer of high density polyethylene; tb) a second layer, the composition of said second layer being chosen from the group consisting of polymers and adheives; and (c) a third primer layer, the composition of said primer layer ha~ing been made from a primer comprising a ma~or fraction of a Lewis base and components of a cyanoacrylate material, said third layer being between said first and second layers.
:l.U
In a further aspect thereof the present invention provides a multiple layer sheet material, including: (a) a first layer of high density polyethylene; (b) a second layer; (c) a third primer layer, the composition of said primer layer comprising a ma~or fraction of a Lewis base, said third primer layer being between said first and second layers; and (d) a fourth layer of metal foil, said second layer bsing between said third and fourth layers.
2U In a still further aspect thereof the invention provides a multiple layer sheet material, comprising: ~a) a first layer of high density polyethylene; (b~ a second layer, the composition of said second layer comprising ethylene acrylic acid ~opolymer; and (c) a third primer layer, the composition of said primer layer comprising a major fraction of a Lewis base; said third layer being adhered in said sheet material to both said first and second layers. Suitably said Lewis base is polyethylene imine.
The present invention again provides a multiple layer sheet material comprising: (a) a first layer of polyethylene having a resin density of at least 0.950, having a narrow molecular weight distribution, and being substantially free of amine compone~ts; (b) a second layer, the composition of said second layer being chosen from the group conslsting of polymers 3~
- ~
. ~
,.
~LX68~0~
and adhesives; and (c) a third primer layer, said third layer including a Lewis base and reacted components from a cyanoacrylate-type material, said third layer being between said first and second layers.
The present invention further provides a multiple layer sheet material comprising, in order: ~a) a first layer of polyethylene having a resin density of at least 0.950, having a narrow molecular weight distribution, and being substantially free of amine components; tb~ a second primer layer of polyethylene imine on one surface of said first layer; (c) a third layer of ethylene acrylic acid copolymer on said second primer layer; and ~d) a fourth layer of metal foil on said third layer.
1~ The invention also provides a multiple layer sheet material including: (a) a first layer of hlgh density polyethylene; (b) a second layer, the composition of said second layer being selected from the group consisting of heat rPsistant polymers and abuse resistant polymers; (c) a third primer layer, 2U the composition of said primer layer comprising a ma~or fraction of a Lewis base, said third layer being between said first and second layers; and (d) a fourth barrier layer bet~een said second and third layers.
The invention also provides a package wherein the packaging sheet material has been modified by virtue of contact with cyanoacrylate-type components. In the modified form of the sheet material, the primer layer includes reacted components from the cyanoacrylate products.
3~
Thus the present invention in another aspect thereof provides a package comprising a packaging sheet material and a product therein, said product including a substantial fraction of cyanoacrylate typ~ component, said packaging sheet material including: (a) a ~irst layer of hlgh density polyethylene; (b) a ' :. : ,, ' ~ 9 second layer, the composltion of said second layer being chosen from the group consisting of polymers and adhesives; and (c) a third primer layer of polyethylene imine, sald third layer being between said first and second layers, said first layer being disposed toward the inside of said package, said package being configured such that no edge of said sheet material is exposed to said product.
The present invention again provides a package comprising a packaging sheet material and a product enclosed therein, said product including a substantial fraction of cyanoacrylate-type component, said packaging sheet material including: (a) a first layer of polyethylene having a resin density of at least 0.950, having a narrow molecular weight distribution, and being substantially free of amine components;
(b) a second layer of ethylene acrylic acid copolymer; (c) a third primer layer, said third layer including polyethylene imine and reacted components from said cyanoacrylate~type product; and (d) a fourth layer of metal foil; said third layer being between said first and second layers, said second layer being between aid 2U third and fourth layers, said first layer being disposed toward the inside of said package, all the layers of said sheet material being adhered to each other, sald package be~ng configured such that no edge of said sheet material is exposed to said product.
The present lnvention will be further illustrated by J way of the accompanying drawings in which:
FIGURE 1 is a cross-section of a three-layer sheet structure of this invention.
3~ FIG~RE 2 is a cross-section of a four-layer sheet structure of this invention.
FIGURE 3 is a cross-section of a six-layer sheet structure of this invention.
: . . .~ , . .
, .. , . - - .: ,~ .:
~ 4 ~
FIGURE 3A is a cross-section of sheet structure not of this invention. It is similar to sheet structure of FIGURE 3, except without the primer layer of FIGURE 3.
FIGURE 3s is a cross-section of another sheet structure not of this invention. It is similar to sheet structure of FIGURE 3 but has the primer layer in the wrong location.
FIGURE 3C is a cross-section of a sheet structure of the invention which has two primer layers.
FIGURE 4 is a pictorial view of an exemplary package of this invention, and including a cyanoacrylate-type product therein.
FIGURE 5 is a greatly enlarged cross-section taken at 5-5 of Figure 4, and showing the primer layers immediately after filling the pac~age with product.
FIGURE 6 ls a greatly enlarged cross-section as in 2U FIGURE 5 shown after a long enough time that the primer layer has been modified and includes reacted components from the product.
In FIGURE 1 is shown a cross-section of a simple sheet structure 110 of the invention, inc'uding two polymeric layers 112 and 116 and a thin primer layer 114 therebetween. Layer 112 2~ is HDPE. The composition of layer 116 is usually polymeric and may be chosen with substantial freedom. Layer 114 is a thin - layer of primer.
In the numbering system, the first digit rep~esents the 3~ FIGURE number. The second and third digits represent the element in the FIGURE. Common second and third digit numbers in the various FIGURES represent common elements. Thus 14 represents the primer layer :ln any of the FIGURES where it is shown. 114 represents the pr:Lmer layer in only FIGURE 1.
"'`' . .
`: .
..
.-"
- .
FIGURE 2 shows a cross-section of a sheet structure 210 of the lnvention of intermediate complexity. Layer 212 is HDPE.
Layer 214 is a thin primer layer. Layer 216 is an adhesive which is effective to adhere to a foil layer 218. with the introduction of the foil layer into the structure, the composition of adhesive layer 216 is selected such that it provides good adhesion between the foil layer 218 and the HDPE
layer 212 through the primer 214. EAA is preferred ~or layer 216.
LU FIGURE 3 shows a cross-section of a sheet structure 310 of the invention having more complexity than the structures of FIGURES 1 and 2, and also having more-preferred functional properties. Layers 312, 314, 316 and 318 are equivalent to the respective ones of those layers in FIGURE 2. Layer 320 is an 1~ adhesive layer which adheres layer 322 to the foil layer 318.
Layer 322 is protective of the foil layer and its composition is selected with that protection property as an important criteria.
As stated earlier, cyanoacrylate is highly xeactive a a 2~ chemical product. it is this strong tendency toward reaction that makes it so difficult to s\design a packaging material to hold it. It is ~urther important that certain layers of the packaging material of this invention not to be permitted to come into direct contact with the cyanoacrylate product. As it has 2~ been found that direct contact with cyanoacrylate can be tolerated by HDPE, it is preferred, and h~ghly functional for the cyanoacrylate-type product to be in direct contact with only the HDPE layer in the flnished packages of this invention. An acceptable package structure is a fin-sealed pouch 411 as seen in 3U FIGURE 4. The peripheral seals 424 are pointed out on 2 of the 4 sides of the pouch.
FIGURE 5 shows a cross-section of the pouch of FIGURE
4. Each of the layers 12, 14, 16, 18, 20, and 22 is shown in its overall relationship to the sheet structure, the package, and the 3~
:. -~ . ~ ~-.,., :
.. .. ........ ... .
:
product. it is seen that the fin-sealed type of construction ensures that the cyanoacrylate product has direct contact only with the hdpe layer. The FIGURE 5 structure is accurately descriptive of the package at the time the product is put into the package.
As is illustrated in FIGURES 1, 2, 3, and 5, the primer layer 14 is extremely thin. It is important that the primer layer be continuous, in order to met its minimum required functional parameter. Meeting the minimum required functional u parameters, however, does not impose. any minimum requirements for physical thickness of the primer layer beyond that required for continuity. The typical quantity of a PEI present in the sheet structure is of the order of 0.04 lbs. per 3000 square foot ream.
In practice, the presence of layer 14 as a distinct layer is not visually detectable by normal microscopic examination of a cross-section of the sheet structure up to the time it is brought into contact with a cyanoacrylate-type product.
FIGURE 6 represents the cross-section as in FIGURE 5, 2~ but after the cyanoacrylate product has been in the package for a while. The significant change is that a visible layer 614R has developed at layer 14, which was also the interface of iayers 12 and 16 for aperance purposes when the sheet material was formed.
For example, in packages evaluated after one week of storage at 120F., the new layer as at 614R was 0,4 to 0.7 mil thick.
Packages evaluated after four weeks of storage at 1~0F. had layers 614R which were 0.9 to 1.6 mils thick. A primary component of the new layer 614R is reacted polymer of cyanoacrylate. Notably, the storage conditions cited herein are unusual in that they accelerate, in many respects, the normal process of aging for both the packaging material and the product.
Thus, the tests iterated herein may repre~ent the entire normal shelf life of the packaged product, or even beyond. ;~
In some experimentally-made sheet materials which were _ g _ :
. . :..
:
LD~
otherwise the same as the sheet materials 10 of the invention, the primer layer 14 was not continuous, but unintentionally had small discontinuities of pin-hole size. Packages made with these sheet materials were not satisfactory. On inspection of the filled and sealed packages after a short storage period of 1 or 2 weeks, spot delaminations were unex]pectedly observed. On detail inspection, discontinuities were identified ad~acent each spot delamination. The discontinuities were visible to microscopic inspection, in the reacted layer 614R. No spot delaminations were observed which could not be as~sociated with a dlscontlnuity.
Thus the inventors have reached the conclusion that the primer layer 14 serves some function of the nature of lmpending the migration of the cyanoacrylate product to the surface of the surface of the foil 18. it appears that the cyanoacrylate does penetrate, and pass through any discontinuity of the primer layer 14, to swell the layer 16, and react at the foil layer 18 to cause delamination. The inventors herein have concluded that the continuity of primer layer 14 is critical to operability of the invention. To that end, it is desirable to treat the surface of the HDPE layer, as necessary, such as by corona discharge, to ensure good wetting of the HDPE layer by the PEI when it is 2U applied.
In certain cases, ~t may be desirable to have additional layers between ~PE layer 12 and the primer 14. Such additional layers may be used so long as any interaction they may 2~ have with, or as a result of, the product is acceptable and so long as the primPr layer is continuous as described earl~er and is separated from any foil layer by at least one intervening layer.
3~ Experimentation has shown that, of the polyethylene imines available, the cross linking types are preferable over the non-crosslinking types. it is hypothesized that the P~I may act as a chemically basic electron donor material, and may interact with the product in polymerization, or other reaction of the - .. -. , ~- . . ..
.
, ,.
cyanoacrylate product. Once the cyanoacrylate has reacted, the size of the reacted molecule is apparently such that it is no longer as mobile in the laminated sheet structure, and remains in the vicinity of the reaction site to form a part of the visible layer 14R. Based on the belief that the PEI acts as a catalytic electron donor, it is believed that other Lewis bases, such as J amines and salts of weak acids, should function in a similar manner to impede migration of the product.
Essentially, the presence of the primer layer 14 u impedes migration of the cyanoacryliate through the structure past the primer layer. FIGURE 3A represents a cross-section of sheet structure similar to the six layer structure of FIGURE 3, but without the primer layer 14. Layers 312A, 316A, 318A, 320A and 322A all represent layers equlvalent to the respective layers in 1~ the sheet structures of the invention. Without a primer layer 14, though, the sheet structure is not capable of satisfactorily holding cyanoacrylate-type products wlthout significant deleterious affect on the packaging sheet structure. Typical affects are swelling of polymer layers and delaminatlon. FIGURE
2U 3B represents a cross-section of sheet structure simllar to the structure of FIGURE 3, but with the primer layer 14 in the wrong place. Layers 312B, 314B, 316B, 320B, and 322B all represent layers equivalent to the respective layers in the sheet structure of the invention. Primer layer 14, however, is at the interfacs between the foil 18 and the EAA 16, rather than at the interface between the HDPE 12 and the EAA 16. With the primer thus improperly positioned, namely ad~acent the foil rather than displaced from it, the sheet structure is not capable of satisfactorily holding cyanoacrylate-type products. Typical affects are swelling, especially layer 16, and delamination, 3U particularly at the foil interface. Primers may be used elsewhere in the invention, as seen in FIGUR~ 3C, so as long as the primary of primer between layers 12 and 16 is retained. To that end layer 312C, 314Cl, 316C, 318Ct 320C, and 322C all represent layers equivalent to the respective layers in FIGURE 3.
3~
.~`~..
.
:. ' ,, .. ,. - ' , ~lX684S~
Layers 314C2 is an additional primer layer which may, for example, be used to promote adhesion between layers 320C and 322C. This practice of using one or more additional primer layers, in addition to the primary primer layer at the interface of layers 12 and 16, is fully satisfactory so long as primary primer layer 14, as described herein, is displaced from the product and from the foll by at least one layer, and is between the product and the foil.
In general, of the polymers usually associated with good heat sealing capabilities, HDPE is the least affected by cyanoacrylate-type product. Other polymers are caused, by cyanoacrylate-type products, to swell by 50% to over 150%. As in the case of linear low density polyethylene copolymer (LLDP~), some polymeric materials are even absorbed into the product.
1~ While HDPE is also swelled somewhat, in the better HDPE's, the swelling is 11mited to only about 30%, and overall strength of the package is sustained satisfactorily. While most high density polyethylenes are acceptable, some are more preferred. The preferred polymers are characterized by the following properties.
z~ Resin density should be at least 0.950. The HDPE preferably has a narrow molecular weight distribution. A high degree pf crystallinity in the HDPE layer is desirable, and can be somewhat controlled by the rate of cooling when the HDPE layer is formed by some melt forming process such as extrusion.
2~
The critical elements of the invention are the HDPE
layer 12 which serves as the sealant layer without being unacceptably affected by the cyanoacrylate product, and the primer layer 14. the presence of the primer layer at the disclose disclosed location causes the mobility of the 3~ cyanoacrylate product to be impeded such that it does not readily pass through layer 14 and have harmful affect on the layers 16, 18, etc., which are beyond layers 12 and 14, a viewed from the layer 12 surface through the sheet material. Thus, the compositions of the various layers 16, 18, etc., beyond layer 14 ~: .
.
:: : ' 1~840~
may not need to be selected for their resistance to cyanoacrylate. Rather, they may be selected for their other desirable properties. thus, layer 16 is defined rather broadly, as a polymer or an adhesive, and may be selected for the properties desired. in a three layer structure as in FIGURE 1, layer 16 may, for example, conveniently be any polymer which adheres well to the primed side of the HDPE layer. Typical layer 1~ polymers would be low density polyethylene ~LDPE~, HDPE, and propylene ethylene copolymer (PPE). Where a fourth layer is present in the sheet material, then the layer 16 must adhere well u to it as well as to the interface at layers 12 and 14. In these structures, layer 16 may be considered to be a layer serving primarily an adhesive function. The adhesive layer may be polymeric adhesive. Where the fourth layer is metal ~-oil, and adhesive polymer such as EAA is known to adhere well to foil and 1~ is preferred for layer 1~. Where the fourth layer 18 is polymeric, an adhesive polymer with graft substitutions of carboxy moietics such as maleic anhydride may be preferred. In some cases, adhesive emulsions may be used. In general, the selection of material for layer 16 depends on the definition of 2~ its function in the sheet structure, whether it be of a protective nature, as may be true in a three layer structure, or an adhesive nature in structures having more than three layers.
The compositions, then, of layers 1~ and 14 are 2~ selected with the primary purpose - in addition to their normal package structural functions - of controlling migration of the cyanoacrylate product through the sheet material. When properly selected and applied, they functionally control the migration of the cyanoacrylate through the sheet material, such that the compositions of all the other layers may be selected without primary consideration of their susceptibillty to cyanoacrylate.
Thus layer 18 is a metal foil layer which would be highly susceptible to loss of adhesion to polymers in the presence of cyanoacrylate-type products. Rather it is selected for its excellent properties as a barrier against passage of any matter ~5 , , .
. . .
- ~'.. ~,; ' i - - :
" ~. . .
~2~8405~
through the package sheet material, into or out of the package.
Other barrier materials may be used in the invention. Along with selection of the barrier material, if one is used, prop~r materlals are selected from those known in the art, for the layers ad~acent the barrier layer to ensure adhesion to, and compatibility with, the rest of the ~sheet structure. Exemplary of possible alternate barrier materials are vinylidene chloride copolymPrs, ethylene vinyl alcohol copolymers, and blends including ma;or fractions of these.
Layer 16 is preferably E~A, another material susceptible of being greatly swelled by cyanoacrylate. But, with the protection provided by layers 12 and 14, the EAA is not thus disastrously affected by the product and may be selected for its excellent adhesive properties to the metal foil. Likewise layers 1' 20 and 22 may also be selected without primary consideration of direct interaction with the product. By the same consideration, the layers 16 through 22, as well as additional layers may be selected with substantial freedom as long as the layers 12 and 14 serve a protective function between the layers 16 through 22 and 2~ the product.
The most preferred structure of the sheet mater~al herein is that illustrated by FIGURES 3, 5, and 6. The sealant layer 12 and the primer layer 14 are narrow molecular weight HDPE
and crosslinking PEI respectively. "Narrow molecular weight" is a relative term, used by the industry, that identifies the sub;ect group of HDPE polymers by sub~ectively comparing their molecular weight distributions with those of other HDPE polymers.
Layer 16 is EAA which serves as an adhesive to the metal foil barrier layer 18. Layer 20 is preferably EAA which serves as an adhesive between the foil layerl8 and layer 22 which is desirably a layer of polymer which is selected for either its excellent abuse resistance or lts heat resistance. Whlle a preferred composition for layer 22 is HDPE, other materials may be preferred for some uses. Exemplary of these are oriented 3~ ;
.... ... ..... .
. . .
. .
,, -: - . , .; -.. ..
polypropylene, oriented polyester, and orlented nylon. In some preferred embodiments, the layer 22 composition is LDPE. The composition oE the adhesive layer 20 is selected in view of the selected compositions of both layers 18 and 22. Additional layers may be used as dictated by the situation, such as for printing, pigmenting, etc.
!j In order for the combined properties of the HDPE in layer 12 and the primer in layer 14 to provlde protection for the other material layer in the sheet structure, namely protection from the cyanoacrylate product, it is important that the HDPE and PEI layers be interposed between the cyanoacrylate and the other layers at all areas where cyanoacrylate is in contact with the packaging sheet material. Illustratlve of this principle is a fin-sealed package as illustrated in FIGURES 4, 5, and 6.
1~- Formation of a finished package as shown in FIGURE 4, from multiple layer sheet materials, is conventionally known in the industry. While the sheet structures disclosed herein are highly unusual, forming them into a finished package is relatively straight forward, as by means of conventionally forming heat 2U seals about the periphery as shnwn in FIGURE 4. The development of the vl~ible layer in its role in impending penetration of cyanoacrylate into the rest of the packaging structure.
The process of making the sheet structure of the 2' invention will now be discussed in terms of the preferred embodiments of the more complex structure; and it will be seen that the simplier structures are in some cases substructures thereof. The discussion of complex structures as in FIGURE 3, thus, also includes the general types of processes which are used to make the simpler 3 or 4 layer structures.
3~
In the first operation, a layer of HDPE is formed, as by an extrusion process. The process is designed for relatively slow cooling of the extruded HDPE layer in order to encourage development of crystallinity. A preferred process is tubular 3~
,r'~
' ~: . . ' ,- , , ' .. ~ :.' '; :', ' . .. .. .
: . . : :'i '' ~'": ~ " ' ~ 34l:~9 blown extrusion. Another acceptable process is cast extrusion where the sheet is cast onto a relatively warm roll and where the elevated temperature are held over a perlod of time, down stream of the extrusion, which is conducive to development of crystallinity. The HDPE layer is then preferably corona treated to a level of at least 38 dynes/cm. of surface energy. the treated side of the HDPE is then primed with a PEI prlmer solution and dried, leaving a continuous layer of PEI on the surface of the HDPE. The primed sicle of the ~DPE layer is then extrusion laminated to aluminum foil uslng EAA as the extrusion laminant. The structure at this state is represented by FIGURE
2. The structure as represented by FIGURE 3 iS completed by extrusion laminating a previously formed abuse resistant layer, such as HD~E, to the exposed side of the foil, using EAA as the extrusion laminant.
If desired, the sheet material may then be reacted with cyanoacrylate moieties, to form a sheet material having a reacted primer layer 14R, before forming it into a package structure as in FIGURE 4. The reaction may be carried out by contacting the HDPE layer 12 with the cyanoacrylate moieties.
In making the 3-layer structure, representad by FIGURE
1, the HDPE layer is formed, treated and primed as previously discussed. Layer 16 is then added by an appropriate process. A
typical process is extrusion coating of the appropriate material onto the primed surface. In another exemplary process, layer 16 is formed in a separate operation and is ~oined to primer layer 14 by heat and pressure lamination at a hot nip, or may be extrusion laminated to layer 14 by using an intervening layer of an extrusion laminant.
Thus it is seen that the invention provides a packaging sheet material capable of holding cyanoacrylate-type products.
it further provides a sheet material which has excellent barrier properties to passage of matter through the sheet material. Even .. , , ~ : :
.... - ~, ... .
more significantly, the invention provides a sheet material which can be made into a closed and sealed package capable of holding a cyanoacrylate-type product.
The sheet materials of this invention are also, of course, capable of holding products which have lower chemical activity than cyanoacrylate. In those cases, materials which are less preferred for holding cyanoacrylate may be more desirable because of other advantages such as economics or processing advantages.
:l u 1~;
ZU
.~ .
Z~ .
'', ' '' ~
:. -~ . ~ ~-.,., :
.. .. ........ ... .
:
product. it is seen that the fin-sealed type of construction ensures that the cyanoacrylate product has direct contact only with the hdpe layer. The FIGURE 5 structure is accurately descriptive of the package at the time the product is put into the package.
As is illustrated in FIGURES 1, 2, 3, and 5, the primer layer 14 is extremely thin. It is important that the primer layer be continuous, in order to met its minimum required functional parameter. Meeting the minimum required functional u parameters, however, does not impose. any minimum requirements for physical thickness of the primer layer beyond that required for continuity. The typical quantity of a PEI present in the sheet structure is of the order of 0.04 lbs. per 3000 square foot ream.
In practice, the presence of layer 14 as a distinct layer is not visually detectable by normal microscopic examination of a cross-section of the sheet structure up to the time it is brought into contact with a cyanoacrylate-type product.
FIGURE 6 represents the cross-section as in FIGURE 5, 2~ but after the cyanoacrylate product has been in the package for a while. The significant change is that a visible layer 614R has developed at layer 14, which was also the interface of iayers 12 and 16 for aperance purposes when the sheet material was formed.
For example, in packages evaluated after one week of storage at 120F., the new layer as at 614R was 0,4 to 0.7 mil thick.
Packages evaluated after four weeks of storage at 1~0F. had layers 614R which were 0.9 to 1.6 mils thick. A primary component of the new layer 614R is reacted polymer of cyanoacrylate. Notably, the storage conditions cited herein are unusual in that they accelerate, in many respects, the normal process of aging for both the packaging material and the product.
Thus, the tests iterated herein may repre~ent the entire normal shelf life of the packaged product, or even beyond. ;~
In some experimentally-made sheet materials which were _ g _ :
. . :..
:
LD~
otherwise the same as the sheet materials 10 of the invention, the primer layer 14 was not continuous, but unintentionally had small discontinuities of pin-hole size. Packages made with these sheet materials were not satisfactory. On inspection of the filled and sealed packages after a short storage period of 1 or 2 weeks, spot delaminations were unex]pectedly observed. On detail inspection, discontinuities were identified ad~acent each spot delamination. The discontinuities were visible to microscopic inspection, in the reacted layer 614R. No spot delaminations were observed which could not be as~sociated with a dlscontlnuity.
Thus the inventors have reached the conclusion that the primer layer 14 serves some function of the nature of lmpending the migration of the cyanoacrylate product to the surface of the surface of the foil 18. it appears that the cyanoacrylate does penetrate, and pass through any discontinuity of the primer layer 14, to swell the layer 16, and react at the foil layer 18 to cause delamination. The inventors herein have concluded that the continuity of primer layer 14 is critical to operability of the invention. To that end, it is desirable to treat the surface of the HDPE layer, as necessary, such as by corona discharge, to ensure good wetting of the HDPE layer by the PEI when it is 2U applied.
In certain cases, ~t may be desirable to have additional layers between ~PE layer 12 and the primer 14. Such additional layers may be used so long as any interaction they may 2~ have with, or as a result of, the product is acceptable and so long as the primPr layer is continuous as described earl~er and is separated from any foil layer by at least one intervening layer.
3~ Experimentation has shown that, of the polyethylene imines available, the cross linking types are preferable over the non-crosslinking types. it is hypothesized that the P~I may act as a chemically basic electron donor material, and may interact with the product in polymerization, or other reaction of the - .. -. , ~- . . ..
.
, ,.
cyanoacrylate product. Once the cyanoacrylate has reacted, the size of the reacted molecule is apparently such that it is no longer as mobile in the laminated sheet structure, and remains in the vicinity of the reaction site to form a part of the visible layer 14R. Based on the belief that the PEI acts as a catalytic electron donor, it is believed that other Lewis bases, such as J amines and salts of weak acids, should function in a similar manner to impede migration of the product.
Essentially, the presence of the primer layer 14 u impedes migration of the cyanoacryliate through the structure past the primer layer. FIGURE 3A represents a cross-section of sheet structure similar to the six layer structure of FIGURE 3, but without the primer layer 14. Layers 312A, 316A, 318A, 320A and 322A all represent layers equlvalent to the respective layers in 1~ the sheet structures of the invention. Without a primer layer 14, though, the sheet structure is not capable of satisfactorily holding cyanoacrylate-type products wlthout significant deleterious affect on the packaging sheet structure. Typical affects are swelling of polymer layers and delaminatlon. FIGURE
2U 3B represents a cross-section of sheet structure simllar to the structure of FIGURE 3, but with the primer layer 14 in the wrong place. Layers 312B, 314B, 316B, 320B, and 322B all represent layers equivalent to the respective layers in the sheet structure of the invention. Primer layer 14, however, is at the interfacs between the foil 18 and the EAA 16, rather than at the interface between the HDPE 12 and the EAA 16. With the primer thus improperly positioned, namely ad~acent the foil rather than displaced from it, the sheet structure is not capable of satisfactorily holding cyanoacrylate-type products. Typical affects are swelling, especially layer 16, and delamination, 3U particularly at the foil interface. Primers may be used elsewhere in the invention, as seen in FIGUR~ 3C, so as long as the primary of primer between layers 12 and 16 is retained. To that end layer 312C, 314Cl, 316C, 318Ct 320C, and 322C all represent layers equivalent to the respective layers in FIGURE 3.
3~
.~`~..
.
:. ' ,, .. ,. - ' , ~lX684S~
Layers 314C2 is an additional primer layer which may, for example, be used to promote adhesion between layers 320C and 322C. This practice of using one or more additional primer layers, in addition to the primary primer layer at the interface of layers 12 and 16, is fully satisfactory so long as primary primer layer 14, as described herein, is displaced from the product and from the foll by at least one layer, and is between the product and the foil.
In general, of the polymers usually associated with good heat sealing capabilities, HDPE is the least affected by cyanoacrylate-type product. Other polymers are caused, by cyanoacrylate-type products, to swell by 50% to over 150%. As in the case of linear low density polyethylene copolymer (LLDP~), some polymeric materials are even absorbed into the product.
1~ While HDPE is also swelled somewhat, in the better HDPE's, the swelling is 11mited to only about 30%, and overall strength of the package is sustained satisfactorily. While most high density polyethylenes are acceptable, some are more preferred. The preferred polymers are characterized by the following properties.
z~ Resin density should be at least 0.950. The HDPE preferably has a narrow molecular weight distribution. A high degree pf crystallinity in the HDPE layer is desirable, and can be somewhat controlled by the rate of cooling when the HDPE layer is formed by some melt forming process such as extrusion.
2~
The critical elements of the invention are the HDPE
layer 12 which serves as the sealant layer without being unacceptably affected by the cyanoacrylate product, and the primer layer 14. the presence of the primer layer at the disclose disclosed location causes the mobility of the 3~ cyanoacrylate product to be impeded such that it does not readily pass through layer 14 and have harmful affect on the layers 16, 18, etc., which are beyond layers 12 and 14, a viewed from the layer 12 surface through the sheet material. Thus, the compositions of the various layers 16, 18, etc., beyond layer 14 ~: .
.
:: : ' 1~840~
may not need to be selected for their resistance to cyanoacrylate. Rather, they may be selected for their other desirable properties. thus, layer 16 is defined rather broadly, as a polymer or an adhesive, and may be selected for the properties desired. in a three layer structure as in FIGURE 1, layer 16 may, for example, conveniently be any polymer which adheres well to the primed side of the HDPE layer. Typical layer 1~ polymers would be low density polyethylene ~LDPE~, HDPE, and propylene ethylene copolymer (PPE). Where a fourth layer is present in the sheet material, then the layer 16 must adhere well u to it as well as to the interface at layers 12 and 14. In these structures, layer 16 may be considered to be a layer serving primarily an adhesive function. The adhesive layer may be polymeric adhesive. Where the fourth layer is metal ~-oil, and adhesive polymer such as EAA is known to adhere well to foil and 1~ is preferred for layer 1~. Where the fourth layer 18 is polymeric, an adhesive polymer with graft substitutions of carboxy moietics such as maleic anhydride may be preferred. In some cases, adhesive emulsions may be used. In general, the selection of material for layer 16 depends on the definition of 2~ its function in the sheet structure, whether it be of a protective nature, as may be true in a three layer structure, or an adhesive nature in structures having more than three layers.
The compositions, then, of layers 1~ and 14 are 2~ selected with the primary purpose - in addition to their normal package structural functions - of controlling migration of the cyanoacrylate product through the sheet material. When properly selected and applied, they functionally control the migration of the cyanoacrylate through the sheet material, such that the compositions of all the other layers may be selected without primary consideration of their susceptibillty to cyanoacrylate.
Thus layer 18 is a metal foil layer which would be highly susceptible to loss of adhesion to polymers in the presence of cyanoacrylate-type products. Rather it is selected for its excellent properties as a barrier against passage of any matter ~5 , , .
. . .
- ~'.. ~,; ' i - - :
" ~. . .
~2~8405~
through the package sheet material, into or out of the package.
Other barrier materials may be used in the invention. Along with selection of the barrier material, if one is used, prop~r materlals are selected from those known in the art, for the layers ad~acent the barrier layer to ensure adhesion to, and compatibility with, the rest of the ~sheet structure. Exemplary of possible alternate barrier materials are vinylidene chloride copolymPrs, ethylene vinyl alcohol copolymers, and blends including ma;or fractions of these.
Layer 16 is preferably E~A, another material susceptible of being greatly swelled by cyanoacrylate. But, with the protection provided by layers 12 and 14, the EAA is not thus disastrously affected by the product and may be selected for its excellent adhesive properties to the metal foil. Likewise layers 1' 20 and 22 may also be selected without primary consideration of direct interaction with the product. By the same consideration, the layers 16 through 22, as well as additional layers may be selected with substantial freedom as long as the layers 12 and 14 serve a protective function between the layers 16 through 22 and 2~ the product.
The most preferred structure of the sheet mater~al herein is that illustrated by FIGURES 3, 5, and 6. The sealant layer 12 and the primer layer 14 are narrow molecular weight HDPE
and crosslinking PEI respectively. "Narrow molecular weight" is a relative term, used by the industry, that identifies the sub;ect group of HDPE polymers by sub~ectively comparing their molecular weight distributions with those of other HDPE polymers.
Layer 16 is EAA which serves as an adhesive to the metal foil barrier layer 18. Layer 20 is preferably EAA which serves as an adhesive between the foil layerl8 and layer 22 which is desirably a layer of polymer which is selected for either its excellent abuse resistance or lts heat resistance. Whlle a preferred composition for layer 22 is HDPE, other materials may be preferred for some uses. Exemplary of these are oriented 3~ ;
.... ... ..... .
. . .
. .
,, -: - . , .; -.. ..
polypropylene, oriented polyester, and orlented nylon. In some preferred embodiments, the layer 22 composition is LDPE. The composition oE the adhesive layer 20 is selected in view of the selected compositions of both layers 18 and 22. Additional layers may be used as dictated by the situation, such as for printing, pigmenting, etc.
!j In order for the combined properties of the HDPE in layer 12 and the primer in layer 14 to provlde protection for the other material layer in the sheet structure, namely protection from the cyanoacrylate product, it is important that the HDPE and PEI layers be interposed between the cyanoacrylate and the other layers at all areas where cyanoacrylate is in contact with the packaging sheet material. Illustratlve of this principle is a fin-sealed package as illustrated in FIGURES 4, 5, and 6.
1~- Formation of a finished package as shown in FIGURE 4, from multiple layer sheet materials, is conventionally known in the industry. While the sheet structures disclosed herein are highly unusual, forming them into a finished package is relatively straight forward, as by means of conventionally forming heat 2U seals about the periphery as shnwn in FIGURE 4. The development of the vl~ible layer in its role in impending penetration of cyanoacrylate into the rest of the packaging structure.
The process of making the sheet structure of the 2' invention will now be discussed in terms of the preferred embodiments of the more complex structure; and it will be seen that the simplier structures are in some cases substructures thereof. The discussion of complex structures as in FIGURE 3, thus, also includes the general types of processes which are used to make the simpler 3 or 4 layer structures.
3~
In the first operation, a layer of HDPE is formed, as by an extrusion process. The process is designed for relatively slow cooling of the extruded HDPE layer in order to encourage development of crystallinity. A preferred process is tubular 3~
,r'~
' ~: . . ' ,- , , ' .. ~ :.' '; :', ' . .. .. .
: . . : :'i '' ~'": ~ " ' ~ 34l:~9 blown extrusion. Another acceptable process is cast extrusion where the sheet is cast onto a relatively warm roll and where the elevated temperature are held over a perlod of time, down stream of the extrusion, which is conducive to development of crystallinity. The HDPE layer is then preferably corona treated to a level of at least 38 dynes/cm. of surface energy. the treated side of the HDPE is then primed with a PEI prlmer solution and dried, leaving a continuous layer of PEI on the surface of the HDPE. The primed sicle of the ~DPE layer is then extrusion laminated to aluminum foil uslng EAA as the extrusion laminant. The structure at this state is represented by FIGURE
2. The structure as represented by FIGURE 3 iS completed by extrusion laminating a previously formed abuse resistant layer, such as HD~E, to the exposed side of the foil, using EAA as the extrusion laminant.
If desired, the sheet material may then be reacted with cyanoacrylate moieties, to form a sheet material having a reacted primer layer 14R, before forming it into a package structure as in FIGURE 4. The reaction may be carried out by contacting the HDPE layer 12 with the cyanoacrylate moieties.
In making the 3-layer structure, representad by FIGURE
1, the HDPE layer is formed, treated and primed as previously discussed. Layer 16 is then added by an appropriate process. A
typical process is extrusion coating of the appropriate material onto the primed surface. In another exemplary process, layer 16 is formed in a separate operation and is ~oined to primer layer 14 by heat and pressure lamination at a hot nip, or may be extrusion laminated to layer 14 by using an intervening layer of an extrusion laminant.
Thus it is seen that the invention provides a packaging sheet material capable of holding cyanoacrylate-type products.
it further provides a sheet material which has excellent barrier properties to passage of matter through the sheet material. Even .. , , ~ : :
.... - ~, ... .
more significantly, the invention provides a sheet material which can be made into a closed and sealed package capable of holding a cyanoacrylate-type product.
The sheet materials of this invention are also, of course, capable of holding products which have lower chemical activity than cyanoacrylate. In those cases, materials which are less preferred for holding cyanoacrylate may be more desirable because of other advantages such as economics or processing advantages.
:l u 1~;
ZU
.~ .
Z~ .
'', ' '' ~
Claims (45)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A multiple layer sheet material, wherein all the layers are firmly adhered to each other, including: (a) a first layer of high density polyethylene; (b) a second layer, the composition of said second layer being chosen from the group consisting of polymer and adhesives; and (c) a third primer layer, the composition of said primer layer having been made from a primer comprising a major fraction of a Lewis base and components of a cyanoacrylate material, said third layer being between said first and second layers
2. A multiple layer sheet material, wherein all the layers are firmly adhered to each other, including: (a) a first layer of high density polyethylene; (b) a second layer; (c) a third primer layer, the composition of said primer layer comprising a major fraction of a Lewis base, said third primer layer being between said first and second layers; and (d) a fourth layer of metal foil, said second layer being between said third and fourth layers.
3. A multiple layer sheet material, wherein all the layers are firmly adhered to each other, comprising: (a) a first layer of high density polyethylene; (b) a second layer, the composition of said second layer comprising ethylene acrylic acid copolymer; and (c) a third primer layer, the composition of said primer layer comprising a major fraction of a Lewis base; aid third layer being adhered in said sheet material to both said first and second layers.
4. A multiple layer sheet material according to Claim 1 wherein aid Lewis base is polyethylene imine.
5. A multiple layer sheet material according to Claim 1 wherein said first layer of high density polyethylene has a narrow molecular weight distribution.
6. A multiple layer sheet material according to Claim 1 wherein said first layer of high density polyethylene has a relatively high degree of crystallinity.
7. A multiple layer sheet material according to Claim 2 or 3 wherein said Lewis base is polyethylene imine.
8. A multiple layer sheet material according to Claim 2 or 3 wherein said first layer of high density polyethylene has a narrow molecular weight distribution.
9. A multiple layer sheet material according to Claim 2 or 3 wherein said first layer of high density polyethylene has a relatively high degree of crystallinity.
10. A multiple layer sheet material according to Claim 4 wherein said first layer of high density polyethylene has a narrow molecular weight distribution.
11. A multiple layer sheet material according to Claim 5 wherein said first layer of high density polyethylene has a relatively high degree of crystallinity.
12. A multiple layer sheet material according to Claim 4, 10 or 11 wherein said polyethylene imine is said third layer is derived from a liquid solution containing a cross-linking type of polyethylene imine.
13. A multiple layer sheet material according to Claim 1, 3 or 4 wherein said second layer comprises an adhesive polymer, and wherein said sheet material further comprises a fourth layer of metal foil and wherein said second layer is between said third and fourth layer.
14. A multiple layer sheet material according to Claim 5 or 6 wherein said second layer comprises an adhesive polymer, and wherein said sheet material further comprises a fourth layer of metal foil and wherein said second layer is between said third and fourth layer.
15. A multiple layer sheet material according to Claim 1, 3 or 4 wherein the composition of said second layer comprises ethylene acrylic acid copolymer.
16. A multiple layer sheet material according to Claim 5 or 6 wherein the composition of said second layer comprises ethylene acrylic acid copolymer.
17. A multiple layer sheet material according to Claim 1, 3 or 4 and including a fourth layer of metal foil, said second layer being between aid third and fourth layers.
18. A multiple layer sheet material according to Claim 5 or 6 and including a fourth layer of metal foil, said second layer being between said third and fourth layers.
19. A multiple layer sheet material according to Claim 2, 3 or 4 and including a fifth layer adhering a sixth layer of polyethylene to said fourth layer of metal foil.
20. A multiple layer sheet material according to Claim 5 or 6 and including a fifth layer adhering a sixth layer of polyethylene to said fourth layer of metal foil.
21. A multiple layer sheet material according to Claim 2, 3 or 4 and including a fifth layer adhering a sixth layer to said metal foil, the composition of said sixth layer being selected from the group consisting of oriented polyester, oriented polypropylene, and oriented nylon.
22. A multiple layer sheet material according to Claim 5 or 6 and including a fifth layer adhering a sixth layer to said metal foil, the composition of said sixth layer being selected from the group consisting of oriented polyester, oriented polypropylene, and oriented nylon.
23. A multiple layer sheet material according to Claim 1, 2 or 3 wherein said first layer of high density polyethylene is substantially free from amine components.
24. A multiple layer sheet material according to Claim 4, 5 or 6 wherein said first layer of high density polyethylene is substantially free from amine components.
25. A multiple layer sheet material, wherein all the layers are firmly adhered to each other, comprising: (a) a first layer of polyethylene having a resin density of at least 0.950, having a narrow molecular weight distribution, and being substantially free of amine components; (b) a second layer, the composition of said second layer being chosen from the group consisting of polymer and adhesives; and (c) a third primer layer, said third layer including a Lewis base and reacted components from a cyanoacrylate-type material, said third layer being between said first and second layers.
26. A multiple layer sheet material according to Claim 25 wherein said Lewis base is polyethylene imine.
27. A multiple layer sheet material according to Claim 24 wherein the composition of said second layer is ethylene acrylic acid copolymer, and wherein aid sheet material further comprises a fourth layer of metal foil and wherein said second layer is between said third layer and aid fourth layer.
28. A multiple layer sheet material according to Claim 26 wherein said Lewis base is polyethylene imine.
29. A multiple sheet material according to Claim 27 and including a fifth layer adhering a sixth layer to said fourth layer of metal foil.
30. A multiple layer sheet material according to Claim 28 wherein the composition of said sixth layer is chosen from the group consisting of oriented polypropylene, oriented polyester, and oriented nylon.
31. A multiple layer sheet material according to Claims 1, 2 or 3 wherein the composition of said second layer is adapted to performing an adhesive function.
32. A multiple layer sheet material according to Claims 4, 5, 6, 25, 26, 27, 28 or 29 wherein the composition of said second layer is adapted to performing an adhesive function.
33. A multiple layer sheet material, wherein all the layers are firmly adhered to each other comprising, in order: (a) first layer of polyethylene having a resin density of at least 0.950, having a narrow weight distribution, and being substantially free of amine components (b) a second primer layer of polyethylene imine on one surface of said first layer; (c) a third layer of ethylene acrylic acid copolymer on aid second primer layer; and (d) a fourth layer of metal foil on said third layer.
34. A multiple layer sheet material according to Claim 25, 26, 27, 28, 29, 30 or 33 and wherein said first layer has a relatively high degree of crystallinity.
35. A multiple layer sheet material, wherein all the layers are firmly adhered to each other, including: (a) a first layer of high density polyethylene; (b) a second layer, the composition of said second layer being selected from the group consisting of heat resistant polymers and abuse resistant polymers; (c) a third primer layer, the composition of said primer layer comprising a major fraction of a Lewis base, said third layer being between said first and second layers; and (d) a fourth barrier layer between said second and third layers.
36. A multiple layer sheet material according to Claim 35 and including a fifth polymeric layer between said third and fourth layers.
37. A multiple layer sheet material according to any one of Claims 35 or 36 wherein said Lewis base is polyethylene imine.
38. A package comprising a packaging sheet material and a product therein, said product including a substantial fraction of cyanoacrylate-type component, said packaging sheet material including: (a) a first layer of high density polyethylene; (b) a second layer, the composition of said second layer being chosen from the group consisting of polymers and adhesives; and (c) a third primer layer of polyethylene imine, said third layer being between said first and second layers, said first layer being disposed toward the inside of said package, all the layers being firmly adhered to each other, said package being configured such that no edge of said sheet material is exposed to said product.
39. A package according to Claim 38, said package having been formed by: (a) bringing portions of said sheet material into face-to-face relationship with each other, defining a common space between said portions; and (b) forming seals between said facing portions about said space to define an enclosure therebetween, and an opening therebetween for introduction product into said enclosure.
40. A package according to Claim 39 wherein said first layer of high density polyethylene has a narrow molecular weight distribution and is substantially free of amine components.
41. A package according to Claim 26, 29 or 30 wherein said polyethylene imine in said third layer is derived from a liquid solution containing a cross-linking type of polethylene imine.
42. A package according to Claim 26, 29 of 30 wherein the composition of said second layer is ethylene acrylic acid copolymer, wherein said sheet material further comprises a fourth layer of metal foil and wherein aid second layer is between said third layer and said fourth layer.
43. A package according to Claim 26, 29 or 30 wherein said third layer of polyethylene imine is derived from a liquid containing polyethylene imine of the cro-linking type, and including a fifth layer of ethylene acrylic acid copolymer adhering a sixth layer of polyethylene to said fourth layer of metal foil.
44. A package comprising a packaging sheet material and a product enclosed therein, said product including a substantial fraction of cyanoacrylate-type component, aid packaging sheet material including: (a) a first layer of polyethylene having a resin density of at least 0.959, having a narrow molecular weight distribution, and being substantially free of amine components; (b) a second layer of ethylene acrylic acid copolymer; (c) a third primer layer, said third layer including polyethylene imine and reacted components from said cyanoacrylate-type product; and (d) a fourth layer of metal foil;
said third layer being between said first and second layers, aid second layer being between said third and fourth layers, said first layer being disposed toward the inside of said package, all the layers of said sheet material being firmly adhered to each other, said package being configured such that no edge of said sheet material is exposed to said product.
said third layer being between said first and second layers, aid second layer being between said third and fourth layers, said first layer being disposed toward the inside of said package, all the layers of said sheet material being firmly adhered to each other, said package being configured such that no edge of said sheet material is exposed to said product.
45. A package according to Claim 44 wherein said metal foil is aluminum foil.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000505643A CA1268409A (en) | 1986-04-02 | 1986-04-02 | Multiple layer sheet materials |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000505643A CA1268409A (en) | 1986-04-02 | 1986-04-02 | Multiple layer sheet materials |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1268409A true CA1268409A (en) | 1990-05-01 |
Family
ID=4132787
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000505643A Expired - Fee Related CA1268409A (en) | 1986-04-02 | 1986-04-02 | Multiple layer sheet materials |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1268409A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2419926A1 (en) * | 2009-04-15 | 2012-02-22 | Brewer Science, Inc. | Acid-etch resistant, protective coatings |
-
1986
- 1986-04-02 CA CA000505643A patent/CA1268409A/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2419926A1 (en) * | 2009-04-15 | 2012-02-22 | Brewer Science, Inc. | Acid-etch resistant, protective coatings |
| EP2419926A4 (en) * | 2009-04-15 | 2013-06-05 | Brewer Science Inc | Acid-etch resistant, protective coatings |
| US8771927B2 (en) | 2009-04-15 | 2014-07-08 | Brewer Science Inc. | Acid-etch resistant, protective coatings |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4777085A (en) | Multiple layer sheet material | |
| US6120860A (en) | Multilayer film structure and packages therefrom for organics | |
| US4685591A (en) | Dispensing tube package | |
| AU667768B2 (en) | Packaging material for long-term storage of food products | |
| EP1728731B2 (en) | Peelable vacuum skin packages | |
| AU672646B2 (en) | Resin laminate | |
| EP0772553B1 (en) | Peelable film structure | |
| EP3732042A1 (en) | Recyclable films for product packaging | |
| EP0795492A2 (en) | Product package having reliable openability | |
| US4698247A (en) | Multiple layer sheet material | |
| WO1998032596A1 (en) | Sealable film | |
| US3759379A (en) | Flexible halogen package | |
| NZ280207A (en) | Polystyrene foam substrate having a film comprising a bonding layer of styrene-butadiene and/or acrylonitrile copolymer adhered thereto; trays formed therefrom | |
| BR112020022084A2 (en) | nozzle pouch and method to do the same | |
| CA1268409A (en) | Multiple layer sheet materials | |
| US4731268A (en) | Multiple layer sheet material | |
| JP2017095106A (en) | Lid material | |
| JP7255088B2 (en) | Manufacturing method of packaging bag | |
| JP5880020B2 (en) | Laminated tube for one hair color | |
| JP7331473B2 (en) | Resin composition for forming sealant layer, and sealant film, laminated film and packaging material using the same | |
| WO1997048775A1 (en) | Polymeric compositions with high self-adhesion and packaging materials and packages made therefrom | |
| JP3983540B2 (en) | Heat-sealable laminated film and use thereof | |
| EP0666800B1 (en) | Peelable film and method of making a peelable film | |
| CA1128879A (en) | Laminate structure for collapsible dispensing containers | |
| JPH02166076A (en) | Bag containing package |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |