JPS6169454A - Multilayer sheet structure and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial use! 'If This invention relates generally to multilayer flexible sheet structures and containers made therefrom. One aspect of the invention is an R-less multilayer flexible sheet structure that includes an oriented substrate structure and is used in the manufacture of flexible tubes of the type commonly used for the packaging and dispensing of pasty preparations. Regarding. Other aspects of the invention relate to such multilayer sheet structures, including - axially oriented substrate structures, and containers and tubes made therefrom.

BACKGROUND OF THE INVENTION Metal foils have long been used to make containers and tubes for packaging and dispensing many products, such as candy bars. A single such container or tube? It was often made from layers. However, containers and tubes made from metal foil have several disadvantages compared to their plastic counterparts. Metal tubes are easily jagged and deformed, crack under moderate bending, and are more expensive.

Recently, a large share of the tube market has been occupied by flexible structural materials with multiple polymer layers. Typically, such tubes have an inner heat-sealable layer, an outer heat-sealable layer, and a barrier layer disposed therebetween. Beyond the conventional structure, additional layers can also be used to impart other properties or qualities.

Non-polymeric layers, such as silver and thin metal foil layers, can also be included in these seven-layer materials to provide special performance features. For example, it is known to provide a layer of thin aluminum foil as a high grade barrier layer. When using metal foils, it is common to use highly adhesive polymers to adhere the foil to adjacent layers. Although such structures have had some success in the commercial market, they exhibit certain drawbacks that limit their use.

Certain products are particularly difficult to retain within the tube due to strong chemical activity that attacks the inner tube layers, especially the aluminum foil layer. A solution to this problem has been to use chemically resistant polymers as the inner tube layer to protect the foil. To eliminate this problem, it has been proposed to use linear low density polyethylene as the inner/runt layer of the tube (US Patent Application Ser. No. 306,675).

It is also known to include a dimensional stability imparting paper layer which is particularly important for printing and which also provides an aesthetic and clean appearance white background. The inclusion of paper waste also improves the permanent fold retention of the tube.

Tube breakage is usually due to rough handling during shipping, resulting in the tube sidewall tearing and the contents leaking out. It has been observed that the paper layer in the laminate is the weakest part of the structure and once it begins to tear, the entire tube weakens and ruptures.

A tube's ability to resist rough handling is related to its ability to withstand a drop test (hereinafter sometimes referred to as a tube drop test).

In this test, a tube filled with product is repeatedly dropped until it breaks. It is believed that all tubes shipped to market, especially regardless of the product they contain, are subject to rough handling and are thus subjected to handling stresses such as those encountered in tube drop testing.

The economical construction of tubes that can reliably pass tube drop tests has remained an open question. To solve this problem, it has been proposed to use a reinforcing layer of biaxially oriented polypropylene inside the sheet structure.Although small improvements have been observed, the dimensional stability and economy of such paper-containing structures has not been improved. It would be desirable to provide an alternative structure that has greater strength and other improved properties.

Improvements in chemical erosion control IE with products in containers are described in U.S. Patent Application No. 1, No. 340,468.
There, a polyacrylic acid/chromium complex primer is used between a metal foil and an ethylene/acrylic acid copolymer on the sealant side of the foil.

It is therefore an object of the present invention to provide a dimensionally stable multilayer groove without the use of paper layers.

Another object of the present invention is to provide a single barless multilayer laminate for tube manufacturing that resists chemical attack by products of the type that are color coated into dispensing containers.

Another object of the present invention is to provide containers and tubes with favorable permanent fold and crease retention properties.

SUMMARY OF THE INVENTION The foregoing objects and advantages of the present invention are realized by a unique multilayer laminated sheet structure that includes an oriented substrate structure and can be formed into containers and tubes for packaging various products. Due to the special structure of this multilayer laminated sheet, the resulting container,
The tube resists chemical attack by packaged ingredients and
It exhibits favorable permanent crease retention and withstands rough handling during shipping without cracking failure.

In one embodiment of the present invention, the multilayer laminate sheet-1 structure includes a first
a first adhesive layer of ethylene-acrylic acid copolymer, a layer of metal foil, and a first adhesive layer of ethylene-acrylic acid copolymer;
A second adhesive layer of acrylic acid copolymer adheres the gold foil layer to the first layer of polyethylene or ethylene copolymer; On the opposite side of one layer is a second layer of nolyethylene or ethylene copolymer. The polyethylene or ethylene copolymer v second layer is about 2/1 to about 6
It is adhered via a first primer to a layer of uniaxially oriented polypropylene having a stretch ratio of /1. ``This oriented polyp a pin/layer is adhered by a third adhesive layer to a second heat sealable layer on the second outer surface of the multilayer laminate sheet material.

It is important that the oriented polypropylene/layer is within a range of about 0.2 to about 4.0 mils from the second outer surface of the multi-12f laminate sheet structure.

In one preferred structure of the invention, three of the second heat-sealable layer, the third adhesive layer and the polypropylene layer
The material is coextruded in the form of a three-layer film substrate structure and simultaneously uniaxially stretched at a stretch ratio of about 271 to about 6/1.

In order for the sheet construction material of the present invention to be formable into a tubular container, the first heat-sealable layer and the U'M2 heat-sealable layer must be compatible with each other upon heat sealing. .

The present invention also provides a flexible dispensing tube made using the multilayer sheet structure described above, with the -axially oriented layer thereof being placed towards the outer surface of the tube.

The present invention also provides a method for manufacturing multilayer sheet structural materials, which method comprises first coextruding a three-layer film and uniaxially stretching the film at a stretch ratio of about 2/1 to about 6/1. Stretch to create a stretched film substrate structure having three parallel layers of low density +O+) ethylene, ethylene-methyl acrylate copolymer, and polypropylene. The polypropylene outer surface of this stretched film is subjected to a corona discharge treatment, and then a primer such as polyethyleneimine is applied to the treated surface. The prefabricated low density polyethylene film is then extrusion laminated to the corona treated and primed polypropylene layer using low density polypropylene as an extrusion layering agent, and then the prefabricated low density , tr +7 ethylene film is extrusion laminated to the aluminum foil (gold foil) layer using ethylene/acrylic acid copolymer as an extrusion layering agent. A polyacrylic acid based primer can optionally be applied to the exposed surfaces of the foil.

Finally, the foil is extruded with a coextrusion consisting of an ethylene/acrylic acid copolymer layer and a 4-layer or linear low-density polyethylene layer so that the ethylene/acrylic acid copolymer layer is in direct contact with the foil. , coextrusion coating.

Specifics 711Q of the present invention will be further explained with reference to the drawings.

In FIG. 1, the multilayer laminated sheet structure is generally designated by 1.
It is indicated by 0. Both layers 12 and 20 are low density polyethylene (LrlPE). Layer 22 is pigmented low density polyethylene. Layer 14 is an ethylene acrylic acid (EMA) copolymer. Layer 16 is polypropylene. Layer 18 is polyethyleneimine (PE
I) Primer. Both layers 24 and 30 are ethylene acrylic acid (EAA) copolymers. Layer 26 is aluminum foil. Layer 28 is a chromium polyacrylate complex primer and layer 32 is linear low density polyethylene (LLDPE). Thus, the multilayer seven-piece structure shown in FIG. 1 does not include a paper layer.

To realize the advantages of the present invention, the polypropylene layer 6 must be uniaxially stretched with a stretch ratio of about 2/1 to about 6/1. Further, when the axially oriented polypropylene layer is between 0.2 mil and about 1.5 mils, preferably between about 1 and about 1.5 mils, from the outer structural surface of the tube, It turns out that there are unexpected benefits.

To impart desirable properties that are advantageous to containers made from the multilayer sheet structure of the present invention, it is important that the polypropylene layer is uniaxially oriented and that this layer is located at a certain distance from the outer surface of the container. It is important that Accordingly, the polypropylene layer 16 is uniaxially stretched to the desired stretch ratio and then laminated, e.g. by extrusion lamination, with the LDPE layers 12 all 12 using the EMA adhesive layer 14 as extrusion laminate, layers 12.14 and 12. A film-like base structure consisting of 16 is made. Alternatively, and more conveniently, layers 3.2 + 14 and 16 may be co-extruded to form a film-like base structure consisting of these three layers, which is then uniaxially stretched to achieve the desired orientation of the IJ propylene layer j6. You can also get the ratio.

Regardless of the method of preparation of the film-like substrate, the polypropylene layer is corona discharge treated, coated with one layer of PEI primer 18, and then coated with layers 20, 22, 24, 26, 2
It is extrusion laminated to the LDPE layer 20 of the base structure consisting of 8 and 32. The latter layer 20.22.24.26゜2
The substrate structure 8, 32 may be in the form of a separate film, which is applied as an extrusion layer over one layer of PEI as described above to form a film of layer L2.14°16. It may also be extrusion laminated to a similar substrate structure.

The advantage of including a uniaxially oriented tripropylene layer is that this layer can be
MD: that is, a direction at 90° with respect to the MD).

Whether the PP (polypropylene) layer is stretched in the machine direction (MD) or in the transverse direction (CMD), the stretching ratio is from about 2:1 to about 6=1, preferably from about 3:1 to Advantageous results are achieved when the ratio is approximately 5:1.

PP is the polymer of choice for layer 16, but if desired this layer can be made of high density if'IJ etylelenohdp
E), P P can be replaced by a stretched layer of polyurethane or nylon with HDPE.

In consideration of the use of a uniaxially oriented PP layer, it is also important that this layer be within a certain distance from the outer surface of the container. Therefore, the PP layer is about 0.2~
It has been found that the most advantageous results are achieved when placed within the range of about ↓ mils, preferably about 1 to about 1.5 mils.

Although FIG. 1 shows a film-like base structure consisting of layers 12, 14 and 16, the present invention includes a film-like base structure made of PP layer J6 and EMA layer 1.4 instead of the entire LDPE layer 12. Underlying structures are also included. The PP layer 16 in such a film is either coated with the EMA layer 4 or extrusion laminated to the EMA layer 14.

The inclusion of uniaxially oriented PP layers in the multilayer sheet structures of the present invention provides several highly advantageous properties to containers made from such structures, as discussed above.

These advantages include greater stability to withstand printing and subsequent processing operations, greater strength, and unexpectedly improved permanent fold customization.

Next, Figure 2.? Here, the entire laminated sheet structure is 1
10. The several layers in this laminated sheet structure are 1.
It is indicated by a code in the 00s.

Thus, for example, both layers 12 (FIG. 1) and 112 (FIG. 2) may be used as the outermost layer of an individual laminated sheet structure.
LDPE layers, these are heat sealable.

Similar functions and code correspondences are in layers 114 and 119.
This applies to each of the remaining layers in FIG. layer 11
4, a maleic anhydride modified polypropylene adhesive layer was used in place of the EMA layer 14 in FIG.
19 is the insulating upper layer or coating used for the decorative mark 1 on layer (32).

In FIG. 3, the entire laminate/channel structure is indicated at 210. In this case as well, layers with the same or similar functions as the layers in the figure are numbered in the 200s corresponding to the two-digit numbers in FIG. Layers 212, 214, and 216 in FIG. 3 thus represent the LDPE, EMA, and PP, respectively, of the film-like substrate described above. Layer 218 is PEI.

Both layers 220 and 232 are LDPg and one layer 224
and 2300 are both made of EMA, layer 226 is aluminum foil, and layer 232 is LDPE.

Figure 4 shows a typical device for making tube fushimotoki for each domain for small production.In this device, tube material is continuously formed from a flat sheet material. Such a device is described in U.S. Pat.
is disclosed in detail. As shown in FIG. 4, the multilayer 7-sheet W of the present invention passes through a guide roller 301 and is fed onto a processing mantle 3 (13) contained in a forming block 3 (15). The inner structural strip W is gradually folded around the mandrel 3 (13) and joined together as a wrap 7-L by heated pressure rollers 307. Arrows A, B and C in FIG.
indicates the stretching direction of the strip W (in this case, the longitudinal direction\AD).

FIG. 5 shows a method of forming a tubeo from a strip W+ of a multi-layer seven-piece structure drawn in the transverse direction (CMD) according to the present invention. Part II'￥1 and Part 5
The equipment used in the figures is the same, and therefore, for the sake of clarity, the reference numerals for the parts of the apparatus in FIG. 5 are the same as those for the corresponding parts in FIG.

In FIG. 5, the strip W1 is fed into the forming apparatus in a direction of stretching substantially 90' relative to the direction of movement, as indicated by arrows E and F. Therefore, in the resulting tube, the sheet structure is in the transverse direction (CMD)
It is in a state where it is oriented.

6 and 7 respectively show a tubular container 401
and 501 are shown. Arrows A and B in Figure 6
and C1 and arrow 2 in FIG.

E and F indicate the stretching direction of the uniaxially stretched layer in each /-t structure.

In order to achieve the greater strength and improved crease retention of the multilayer sheet structure of the present invention and containers made therefrom,
The oriented PP layer should be located within about 0.2 to about 4 mils, preferably about 1 to about [.5 mils] from the outer surface of the sheet structure. , 12 acts as a heat seal layer when forming a lap seal on the sidewall of the chape, so it should be thick enough to reliably form a heat seal as a practical matter. Layer 14 should then be as thin as possible, but still layer 1
It is a bebe that satisfies its ability to bond 2 and 16 together. In practice, the thickness of layer 12 is approximately 0
．． 8 to about 1.2 mils, and the thickness of layer 14 is often from about 0.2 to about 0.3 mils.

Although PEI is shown as layer 18, its use as a primer: in this case it is in the form of a very thin coating, whereas in the drawing it is shown as a much thicker layer for illustration purposes. It is understood that it is a thing. Similarly, layer 2B is shown as a fairly thick layer for illustrative purposes, but is actually applied as a thin coating. Layer 22 is typically white LDPE with pigments.
in the form of a preformed film, typically about 2.
75 to approximately 5 mils thick. Layer 20 (LDPE) is used as an extrusion, r'jj, layering agent to join layers 22 and 16, and its thickness is typically about 1
．． It is about 0 mil.

Layer 24 is traditionally used as an extrusion layer to bond layer 22 to the foil of layer 26. Advantageously, the foil is from about (32)5 to about 0.7 mils thick, depending on the product to be packaged and its use. The foil can be directly extrusion coated with a relatively thick layer of EAA of about 2.0 mil and a layer of LDPE of about 1.2 mil, as shown in FIG. Alternatively, as in Figures 1 and 2, the foil may first be coated with a chromium polyacrylate complex primer (layer 28 in Figure 1, layer 128 in Figure 2). With such primer-coated foils, the primer adds a degree of resistance to chemical attack. The required thickness can be reduced to about 0.5 mil. The thickness of the outer sealant layer of LLDPg may be on the order of about 2.0 mils.

Tube containers made from the multilayer sheet structure of the present invention exhibit improved strength in the g-read drop test described below. Such containers also exhibit unexpectedly high fold retention.

The invention is further illustrated by the following examples.

Example 1 LDPE, EMA and PP were co-extruded using three extruders that supplied raw materials to one co-extrusion die,
Forming a coextruded film consisting of three layers, l,
did. This three-layer coextruded film was uniaxially stretched at a stretch ratio of 3.2/1 to create a 2.0 mil thick stretched three-layer substrate structure. The thickness of each layer was as follows.

LDPE 0.8 mil EMA O, 2 mil PP 1.0 mil The surface of the PP layer was subjected to corona discharge treatment to deposit PE nib primer. This PP layer surface was then extrusion laminated to a preformed 215 mil thick pigmented LD PE film using 1.0 mil thick LD PE as the extrusion layering agent and primed. A base structure consisting of five layers was created. Then this 2.75 mil L D
PE surface layer with 1.0 mil EA as extrusion layering agent
A was extrusion laminated to 0.7 mil aluminum foil. Apply chromium polyacrylate complex primer to the opposite side (exposed side) of the foil and apply 0.5 mil EAA and 2. (15 mil LLDPE was extrusion coated onto the primer surface.

At that time, make sure that the FAA is close to the foil sheet, and LLrlP
F.

The layers were made to form the second outer surface of the completed multilayer sheet structure. The first outer surface of the completed multilayer sheet structure is.

LDPE layer in the -axially stretched three-layer base structure.

Example 2 Another 7-t structure was made using the same methods and materials as Example 1, but with slightly different layer thicknesses. The three layer stretched substrate structure was 2.5 mils thick, with the thickness of each layer as follows:

LDPE 1.2 mil EMA 0.3 mil PP 1.0 mil Furthermore, this example differs from Example 1 in that o, z 5 mil thick aluminum foil and 2.0 mil thick LLDPE were used.

Example 3 Another sheet structure was made using the same methods and materials as Example 2, but the three-layer stretched substrate structure of this example was 2 mils thick;
The thickness of each layer was as follows.

LDPE 0.8mil “Ato”-(Admar)! 0.2 mil PP
1.0 mil Avimar(TM) is an adhesive polymer based on maleic anhydride modified polypropylene.

After the PP layer was corona discharge treated and primed, it was printed with ink and then extrusion laminated into five layers of L D P (3.25 mils thick, corresponding to 120 in FIG. 2).

Example 4 Another sheet structure was made using the same methods and materials as in Example 3, but in this example, 0,2
Mill's EMA (32) was used instead of Mill's "Atomer" and no ink layer was used. The fFP-laminate LDPE layer, corresponding to layer 220 in FIG. 3, was 0.8 mil thick. No chromium polyacrylate complex primer was used. The last three layers (226.230 in Figure 3,
232) was as follows.

Aluminum foil 0.25 mil EAA 2.0 mil L D P
Example 1 below E 1.2 mils
~4 7-t structures and comparison flJA, B, G
Column the arrangement, thickness, and total thickness of each layer of the sheet structure. (The layers marked with a + are the stretched layers). The structure of the comparative IJA is a beepless groove structure, but does not include an axial extension layer. The structure of Comparative Example B includes a -axially oriented PP layer, but the PP layer is located as much as 185 mils from the surface of the sheet structure. Comparative Example C is a conventional sheet structure commonly used commercially to make toothpaste tubes.

Example I LD PF, from 0.
3 mil EMA rice 0.2 mil PP rice 1.0 mil primer LDPE 1°0 mil white LDPK
2.75 mil EAA
1.0 mil aluminum foil 0.7 mil 1 No. primer EAA O, 5 mil LLDPE 2. (15 mil total thickness 10.0 mil actual elliptical example 2 LDPE half 1.2 mil EMA
Next 0.3 mil pp rice
1.0 mil PDP E 1.0 mil white LDPE 2.75 mil F
AA '1.0 mil Aluminum foil o, 25 mil Primer EAA O, 5 mil Example 3 LDPE' 0.8 mil 'Atomer' US 0.2 mil PP ÷
1.0 mil primer ink LDPK 1.0 mil white LDPE 3.25 mil EAA
1.0 mil aluminum foil 0.25 mil primer EAA O, 5 mil L
LDPE 2.0 mil implementation N
14 0.8mil EMA from LDPE
Rice 0.2mil PP”
1.0 mil primer LDPE O, 8 mil white LDPK 3.25 mil EAA
1.0 mil aluminum foil 0.25 mil EAA
2.0mil LDPE
1.2 mil total thickness
10. Mill comparison example A LDPK 2.5 mil LDP
K 0.5mil white LDPK
3.25 mil EAA
1.0 mil aluminum foil
0.25 mil primer EAA O, 5 mil total thickness 1. (14) Mil Comparative Example B LDPE' 2.5 mil LD
PK 1.25 mil pp rice 2.0 mil white EAA
1.5 mil aluminum foil
0.25 mil primer EAA O, 5 mil LL
DPE 2.0 mil total thickness
1. (14) Mill Comparative Example C LDPE 1.5 mil ink white LDPE, 2.0 mil paper
1.6mil LDPE
O.7 mil EAA
3.3 mil aluminum foil 0
7mil EAA 2.0mil LDPE
1.2 mil total thickness
Each of the 13.0 mil Examples 1-3 and Comparative Examples A-G was constructed in accordance with the aforementioned U.S. Patent No. 3,540.
, 959, each was formed into a dispensing tube. Each tube is made with a diameter of 1.11 /
It was molded to 32-inches (34,1#1m1). The tube was then cut to size and a head was injection molded (using a conventional insert) into one end and a cap was attached. The product to be packaged was filled from the open other end, and the other end T (3) was rolled.Then, these filled tubes were subjected to a notebook drop test.

Drop Test: 1. In a head drop test conducted using a tube filled with line drawing polish, the tube was dropped from a height of 4 feet (121,8 degrees) with the capped head facing down. The same tube is repeatedly dropped until it breaks, but the number of large drops for one tube is 11,
In addition, three tubes were used for one persimmon example (comparative example).

In evaluating each tube by this drop test, one drop was counted as one point, and the total scores for each row (three tubes) were averaged to obtain a representative score for each row. Table 1
demonstrated that tubes made using the sheet structure of the present invention have physical strength comparable to Comparative Example A and Snake tubes, and much higher physical strength than Comparative Example C tubes. It shows.

In the use of product-filled tubes, such as line drawing tubes, it is desirable for the tube to flatten as the product is consumed to facilitate subsequent extrusion (dispensing). Therefore, the permanent fold characteristics of the sheet construction material for the tube are predictive of the ability of the tube to remain flat. This property is useful when testing folds in the plane of the sheet structure that correspond to folds when the tube is flattened (i.e., the surface forming the inner surface of the tube, e.g. layer 32 in FIG. This is especially important when matching

When performing the permanent crease test, metal or metal is used to create the crease. The metal type is 1 inch (2s, 4mm
) is a rectangular bar with a square length of 15 inches (381 questions) and weighs 4 pieces) -' (1,814 kF). Each sheet construction specimen is 4 inches (10,16 cm) long and 1 inch (2,54 cIrL) wide. Place the specimen on a flat surface and fold it along its length without making any creases. The spit is then aligned and gently placed on the folded specimen so that the heel folds the specimen flat and stays aligned on the specimen.

After 30 seconds, remove the weight and stand the test piece with its edge down. Thirty seconds after weight removal, measure the angle of the fold using a protractor. Table 11ri shows the permanent crease retention properties of the sheet structure of the present invention! It is better than the permanent crease retention properties of A and B, and is almost as good as that of Comparative Example C (C indicates good).

Table I Example (thickness mill) Drop strength point Permanent crease property 1
10, OLl 23°2 1. (
14) +-(154°3 1.(14)
) 9 34° Comparison A 1. (
14) 11 104° comparison 8 1
. (14) 8 76° comparison C13,
01,22° In comparing the above data, some basic overall comparisons must be pointed out.

The commercial sheet structure of Comparative Example C has good permanent crease properties, poor drop strength, but less than the -/-t structure of other examples.
0% thickness is large and therefore relatively expensive. Although Comparative Examples A and B have good drop strength and are relatively low cost, they have poor permanent crease retention.

Exemplary sheet structures of the present invention provide good drop strength, are relatively low cost, and approach commercial sheet structures in permanent fold characteristics.

As indicated above, it is believed that the strength and permanent crease properties of the sheet construction materials of the present invention are attributable to the uniaxial extension of the PP layers in combination and the proper placement of the PP layers in the structure. Therefore, it is expected that a similar structure in which only the PP layer is stretched, or a similar structure in which the PP layer and the LDPE layer (eg, layer 12 in FIG. 1) are stretched, will yield similar results.

As mentioned above, the advantageous effect of the present invention is that the PP layer or the film 1Δ consisting of PP, EMA and LDPE layers
This is achieved when the substrate structure (FIG. 1) or the equivalent layers of FIGS. 2 and 3 are stretched in the transverse direction (CMD). Therefore, Example 5 below was conducted.

Example 5 Two types of sheet structures having the combination of layers as shown in Fig. 1 (the thickness of each layer is as follows, but the stretching direction is M
D and CMD are different) to the same size (1/11/32
Inch diameter x 7, 7/16 inch length: 3.41 Rin diameter x 18
．． Two types of tubes (89CrIL length) were made.

LDPE semi 0.7 mil E
MA healing 0.3milpp
'l' 2.0 mil PE Niblimer LDPE 0175 mil white LDPK 2.75 mil E
AA O, 75 mil aluminum foil 0.25 mil chromium polyacrylate complex primer EAA Q, 5 mil total thickness 1. (14) Mill (next drawing: MD or CMD) The tube was made by the method described in the above-mentioned US Pat. No. 3,540,959. The PP layer in one sheet structure was stretched in the machine direction (MD) and the PP layer in the other 7-t structure was stretched in the cross direction (CMD). A head was attached to the tube by an extrusion method using a urea resin insert, and a cap was attached. The tube was filled with [Crest BSM (=trademark)] line drawing polish and sealed.

Five tubes in each drawing direction (MD and CMD) were dropped from a height of 4 feet (121,8 m) with their heads down. In the case of MD stretched tube, 5
All of them were broken on the first drop (the tubes in the 4 pieces were broken along the lap seam, and one was broken in the main body). In the case of CMD-oriented tubes, 41 out of 5 tubes withstood 10 drops;
One piece broke at the lap seam and head joint during the first drop.

It should be noted that the thickness of the PP layer in the tube made in Example 5 was 2.0 mil, compared to the 1.0 mil thickness in Examples 1-4. The increased thickness of the PP layer in Example 5 is less disadvantageous in the case of CMD drawn tubes, as shown in Example 5, however, as shown in Example 5.

Generally, the thickness of the PP layer is preferably about 2 mils or less, otherwise the heat sealing (wrapping) conditions during tube forming must be more carefully controlled. Therefore, in practice, the optimal thickness of the PP layer is approximately [
It's a mill.

In the most preferred embodiment of the invention, high density polyethylene can be used in place of polypropylene. This i-fu-sama is shown in No. 81.

In FIG. 8, layer 812 is low density polyethylene and one layer 814 is high density polyethylene. Among the other layers, layer 818 is polyethyleneimine (PE) primer, layer 2320 is low density polyethylene, layer 822 is graded blend colored low density polyethylene, and layer 824 is ethylene/polyethylene.
acrylic acid copolymer, WI826 is aluminum foil, layer 328 is poly'acrylic acid romcomplex zolymer, layer 830 is ethylene-acrylic acid copolymer, and layer 83
2 is linear low density polyethylene (LLDPE).

From FIG. 8, the sheet structure shown in FIG. 8 is different from that of the sheet structure of FIG.
The methyl acrylate copolymer layer 14 has a higher density 4.
+) It can be seen that the sheet structure is the same as that of FIG. 1, except that ethylene is substituted.

As in the construction of embodiments using uniaxially oriented polypropylene, the dense 41J polypropylene layer (814 in Figure 8) may be applied in either the machine direction (MD) or the transverse direction (CM).
D) - axially stretched. The sheet structure shown in FIG. 8 is otherwise manufactured in the same manner as the other embodiments of the invention described above.

i4 When high density polyethylene is used, as in the embodiment shown in FIG.
1 to about 8/1. The high density polyethylene layer should also be placed approximately the same distance from the surface of the sheet structure as the 7P polypropylene layer.

Examples 6 and 7 below illustrate the seat structure shown in FIG.

Example 6 The thickness of each layer is as follows.

LDPE 1. (15mil HD
PK 1.6mil PEI Primer LDPE 1.3mil Pigmented LDP
E 2.25 mil EAA
1. i-mil aluminum foil 0
．． 7 mil polyacrylic acid ROM complex primer EAA O, 5 mil L L
D P E 2.0 mil Example 7 The sheet structure of this example was the same as Example 6 except that an ink layer was interposed on one or both sides of the high-tolerance polyethylene layer.
It was the same as that of

The multi-layer sheet structures illustrated in Examples 6 and 7 above exhibit improved properties similar to the multi-layer sheet structures using uniaxially oriented polypropylene described above.

It will be appreciated by those skilled in the art that it is possible to substitute one polymer layer for another in the sheet structure of the present invention depending on the intended use without reducing the overall performance of the sheet structure. That would be the place to do it. For example, both outer layers of the sheet structure may be made from another heat-sealable polymer. For example, depending on the type of polymer selected for the outer layer 12, another adhesive polymer can be selected for layer 14. Also, in some cases, high-density 41J ethylene or ethylene copolymers may be advantageously used to replace low-density polyethylene (LDPE) in inner layers (e.g., layers 20 and 22) in sheet structures. can. Similarly, image markings or other ink prints can be applied to the sides of each layer.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an example of the multilayer sheet structure of the present invention. FIG. 2 is a new view of an example of the multilayer sheet structure of the present invention. FIG. 3 is a cross-sectional view of an example of the multilayer sheet structure of the present invention. FIG. 4 is a perspective view of a tube forming process showing the manner in which a sheet structure in which several layers are longitudinally stretched is formed into a tube. FIG. 5 is a perspective view similar to FIG. 4 showing the manner in which a sheet structure in which several layers are laterally stretched is formed into a tube. FIG. 6 is a partially cut-away perspective view of a tube container made from a longitudinally stretched multilayer/grooved structure. FIG. 7 is a partially cutaway perspective view of a tube container made from a multilayer/groove structure extending in the beak direction. FIG. 8 is a cross-sectional view of an example of the most advantageous multi-layer/grooved structure of the present invention. Patent Applicant: American Can Company FIG.
I FIG, 2 FIG, 3

Claims (40)

[Claims] (1) A multilayer sheet structure with both outer surfaces heat-sealable, including (a) a first heat-sealable layer forming one outer surface, (b) a first adhesive layer, and (c) a metal foil layer. (d) a second adhesive layer; (e) a first layer of polyethylene or ethylene copolymer; (f) a second layer of polyethylene or ethylene copolymer; (g) a first primer; (h) a layer of a stretched polymer selected from the group consisting of polypropylene, polyethylene, ethylene copolymer, polyethylene-polypropylene blend, nylon, and polyester, with a stretch ratio of about 2/1 to about 6/1; (i ) a third adhesive layer; and (j) a second heat-sealable layer forming a second exterior surface, wherein the stretched polymeric layer has a thickness of about 0.2 to about 4.0 from the second exterior surface. The above multilayer sheet structure is characterized in that it is arranged in a mill position. (2) The multilayer sheet structure according to claim 1, wherein the stretched polymer is stretched in the longitudinal direction. (3) The multilayer sheet structure according to claim 1, wherein the stretched polymer is stretched in the transverse direction. (4) The multilayer sheet structure of claim 1, wherein the stretch ratio of the stretched polymer is from about 3/1 to about 5/1. (5) The multilayer sheet structure of claim 2, wherein the stretch ratio of the stretched polymer is from about 3/1 to about 5/1. (6) The multilayer sheet structure of claim 3, wherein the stretch ratio of the stretched polymer is from about 3/1 to about 5/1. (7) the stretched polymer extends from about 1 to about 1.5 from the second outer surface;
A multilayer sheet structure as claimed in claim 1 located in a mill location. (8) the stretched polymer extends from about 1 to about 1.5 from the second outer surface;
A multilayer sheet structure according to claim 2, which is located at a mill location. (9) the stretched polymer extends from about 1 to about 1.5 from the second outer surface;
4. A multilayer sheet structure as claimed in claim 3 located in a mill location. (10) The stretched polymer extends from about 1 to about 1 mm from the second outer surface.
5. The multilayer sheet structure of claim 4 located at 5 mils. (11) The stretched polymer extends from about 1 to about 1 mm from the second outer surface.
6. The multilayer sheet structure of claim 5 located at 5 mils. (12) The stretched polymer extends from about 1 to about 1 mm from the second outer surface.
7. The multilayer sheet structure of claim 6 located at 5 mils. (13) The multilayer sheet structure according to any one of claims 1 to 12, wherein the stretched polymer is made of polypropylene. (14) The multilayer sheet structure according to any one of claims 1 to 12, wherein the second heat-sealable layer is uniaxially stretched. (15) The multilayer sheet structure according to any one of claims 1 to 12, wherein the second heat-sealable layer is heat-sealable to the first heat-sealable layer. (16) A flexible dispensing tube of a single multilayer sheet construction with both exterior surfaces heat-sealable, comprising, in order from inside to outside: (a) a first heat-sealable layer; (b) a first (c) a layer of metal foil; (d) a second adhesive layer; (e) a first layer of polyethylene or ethylene copolymer; (f) a second layer of polyethylene or ethylene copolymer. (g) a first primer; (h) a layer selected from the group consisting of polypropylene, polyethylene, ethylene copolymers, polyethylene-polypropylene blends, nylon, and polyester, with a draw ratio of about 2/1 to about 6/1; a layer of oriented polymer; (i) a third adhesive layer; and (j) a second heat-sealable layer forming a second exterior surface; from about 0.2 to about 4.0 mils, and the multilayer sheet structure is generally cylindrically shaped with a lap seal between the first and second heat sealable layers. The above-mentioned flexible dispensing tube is characterized by: (17) The flexible dispensing tube according to claim 16, wherein the stretched polymer is uniaxially stretched in the longitudinal direction. (18) The flexible dispensing tube according to claim 16, wherein the stretched polymer is uniaxially stretched in the transverse direction. (19) The stretching ratio of the stretched polymer is about 3/1 to about 5/1.
The flexible dispensing tube according to claim 16. (20) The stretching ratio of the stretched polymer is about 3/1 to about 5/1
The flexible dispensing tube according to claim 17. (21) The stretching ratio of the stretched polymer is about 3/1 to about 5/1.
The flexible dispensing tube according to claim 13. (22) the stretched polymer layer extends from about 1 to about 1 from the second outer surface;
．． Claim 16 located at the 5 mil position
Flexible dispensing tube described in section. (23) the stretched polymer layer extends from about 1 to about 1 from the second outer surface;
．． Claim 17 located at the 5 mil position
Flexible dispensing tube described in section. (24) the stretched polymer layer extends from about 1 to about 1 from the second exterior surface;
．． Claim 18 located at the 5 mil position
Flexible dispensing tube described in section. (25) the stretched polymer layer extends from about 1 to about 1 from the second outer surface;
．． Claim 19 located at the 5 mil position
Flexible dispensing tube described in section. (26) the stretched polymer layer extends from about 1 to about 1 from the second exterior surface;
．． Claim 20 located at the 5 mil position
Flexible dispensing tube described in section. (27) the stretched polymer layer extends from about 1 to about 1 from the second exterior surface;
．． Claim 21 located at the 5 mil position
Flexible dispensing tube described in section. (28) The flexible dispensing tube according to any one of claims 16 to 27, wherein the stretched polymer is polypropylene. (29) The flexible dispensing tube according to any one of claims 16 to 27, wherein the second heat-sealable layer is uniaxially stretched. (30) The flexible dispensing tube according to any one of claims 16 to 27, wherein the second heat-sealable layer is heat-sealable to the first heat-sealable layer. (31) (a) coextruding three polymer layers arranged in the order of a polyethylene layer, a first adhesive layer, and a stretching polymer layer to form a film-like substrate structure from these layers; uniaxially stretching the structure to a stretch ratio of about 2/1 to about 6/1; (b) applying a primer to the stretching polymer layer; (c)
extrusion laminating a layer of polyethylene on the primer coated side of the stretching polymer layer; (d) extrusion laminating the polyethylene layer to the aluminum foil layer using a second polymer adhesive layer as an extrusion layer; and (e) co-extrusion coating the aluminum foil layer with a second adhesive layer and a polyethylene co-extrudate to complete the multi-layer sheet structure. (32) The method of claim 31, wherein the draw ratio is about 2/1 to about 5/1. (33) The method according to claim 31, further comprising the step of applying a chromium polyacrylate complex primer to the aluminum foil before applying the coextrusion coating to the aluminum foil. (34) The method of claim 32, further comprising the step of applying a chromium polyacrylate complex primer to the aluminum foil before applying the coextrusion coating to the aluminum foil. (35) The method according to any one of claims 31 to 34, wherein the stretching polymer is polypropylene. (36) A paperless laminated sheet structure having multiple thermoplastic polymer layers including a layer of uniaxially oriented polymer with a draw ratio of about 2/1 to about 6/1. (37) The paperless laminate sheet according to claim 36, wherein the stretched polymer is selected from the group consisting of polypropylene, polyethylene, ethylene copolymer, polyethylene/polypropylene blend, nylon, and polyester. (38) in order: (a) a first heat sealable layer; (b) a first adhesive layer; (c) a layer of metal foil; (d) a second adhesive layer; (e) a polyethylene or a first layer of ethylene copolymer; (f) a second layer of polyethylene or ethylene copolymer. (g) a primer; (h) a layer of uniaxially oriented high density polyethylene having a stretch ratio of at least about 3/1; and (i) a second heat sealable layer. (39) The paperless laminated sheet structure according to claim 38, wherein the stretch ratio of the high-density polyethylene is about 4/1 to about 6/1. (40) The paperless laminated sheet structure according to claim 38 or 39, wherein the first heat-sealable layer and the second heat-sealable layer are each made of low density polyethylene.