JPS5926259A - Plastic film and bag and large-sized bag - 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 The present invention relates to plastic films and bags and large bags made therefrom.

Plastic bags and large bags, especially T-bags made from polyolefins such as polyethylene.

has been known for a long time and in a wide range of end uses due to its physical properties and low cost.

It has been widely used instead of other materials, especially as liners for garbage cans and in dressing materials such as fertilizers, peat, etc. however.

Although many studies have shown that one-strength paper large bags, especially used for packaging agricultural and horticultural products, can be used instead of multi-ply paper large bags, pillow dog-shaped bags or valve large bags, It has acceptable performance 2 and is sufficiently inexpensive. There is a problem of developing alternatives to plastics.

According to the present invention, at least one wall force comprises a first layer and a second layer, each layer being formed by melt extrusion from a synthetic thermoplastic material, and one of said layers comprising a linear low density ethylene polymer. , (a) a higher density If Y moiety and a second polymer selected from ethylene homopolymers and copolymers of ethylene and at least one other α-olefin
at least one of an ethylene polymer and (bl polypropylene), and the other of said layers is comprised of a linear low density ethylene polymer, and at least one of said layers provides a wall structure; A thermoplastic bag or large bag is provided, characterized in that at least a portion of the outer surface has a higher coefficient of friction than the inner surface.

In the simplest form of a bag or pouch, the wall has just two layers, but it can consist of six or more layers, in which case the two specified layers preferably provide two sides of this wall.

Generally both walls of a bag or large bag will have said multilayer structure 2, but this is not essential. because.

All of the large bags (or bags) in the stack have only one wall in the same direction, ie on the top wall or the bottom wall of all of the said wall 7 large bags.

This is because the benefits of the present invention can still be obtained when only one of the walls is so configured, as long as it is arranged.

Although the wall layers can be separated if necessary.

Preferably they are fused together, in which case the walls can be formed by a method such as co-extrusion, or by co-extrusion.

Thus, also according to one invention, the laminate comprises at least two layers, each of the layers being formed by melt extrusion from a synthetic thermoplastic material, and the first of the layers being formed by melt extrusion. (a) a second ethylene polymer having a higher density deficiency and selected from ethylene homopolymers and copolymers of ethylene and at least one other alpha-olefin; bl polypropylene, and a second of said layers comprises a linear low density ethylene polymer, at least one of said layers provides a face of the multilayer film, and at least one of the surfaces of one face One portion has a higher surface friction coefficient of 7 than the other portion of the film.Featured in that multilayer films are provided.

The layers to be laminated can also be thermally melted while at least one layer is in a thermally softened state as a result of being melted for extrusion. Preferably, the film is made by coextrusion. Simultaneous extrusion.

By extruding two or more different plastic layers through a common die, ll! , consisting of manufacturing a multilayer product in one step. Can the plastic materials forming the layers be extruded through different orifices in the same die, where the layers are extruded as separate entities and melted together downstream of the die?

Alternatively, they can be extruded through the same orifice.

In its simplest form, the film of the present invention has two layers, which provide the inner and outer surfaces, respectively, of the bag or pouch made from the film. However, it can contain more than two layers, thus providing the possibility of further modifying the physical properties of the film and the bags made therefrom.

The film can be a flat film extruded from a slot die, but preferably it is produced by, for example, inflation. It is a tubular film. Preferably, the surface of the film with a higher surface friction coefficient of 7 is provided by one of the two specified layers.

This layer is optionally discontinuous, e.g.

1 or more σ) can be in the form of bands or strips. For example, when the film is a tubular film, the bands or strips can be oriented in or at an angle to the machine direction so that a helical pattern is formed.

Bags and large bags according to the present invention may be made from film such that a surface with a surface friction coefficient greater than 2 provides the outer surface of the bag or large bag wall. Bags and vats can be formed from films in known manner and can be in the form of simple vats or, for example, in the form of billow vats or valve vats.

Linear low density ethylene polymers have a density comparable to that of ordinary low density polyethylene, ie.

It has a density of about 0.925g, but it is Ziegler.

100 carbon less than ordinary low density polyethylene produced by a low pressure process using metal based catalysts such as Phillips, Union Carbide, Dow or standard catalysts and by a high pressure process using peroxide catalysts. It is an ethylene polymer with a low number of CH,- groups per atom. in general.

Linear low-density ethylene polymers contain a small percentage of second α-
Contains olefin as a comonomer.

The secondary α-olefin usually contains at least 4 carbon atoms.

In one of the layers, preferably in the layer that does not provide the exterior surface of the bag or large bag, linear low density ethylene polymer 2 is used in admixture with a second polymer. Linear low density polymers are
Preferably, the ethylene and carbon number are greater than 4, preferably at least 6.

Most preferred are copolymers with alpha-olefins greater than 7. An example of such α-olefin percentage is:
Hexene-1, Octyne-1+ and Decene-1. The second polymer is preferably polyethylene or a copolymer of ethylene and other alpha-olefins and has a higher density 7 than the linear low density polymer with which it is mixed. in general.

said second ethylene polymer at least 0.926g;
/cm3 and has a density of 0.926 to 0.940
It has a density in the range of 17 cm3. So-called medium-density obscuring polymer.

and high density polymers having a density in the range 0.9/11 to 0.965 g/am3 or possibly higher. Preferably it is 0
．． It has a density2 ranging from 930 to 0.9115 g/crn3.

Properties of bags and large bags, especially burst resistance, tear resistance1
To obtain the optimal combination of elasticity and tensile strength, blend the two polymers.

About 0.914 to about 0.937 g 7 when determined from the following equation % Formula %
cm3° more preferably about 0.920 to about 0.9351
7cm3. Most preferably about 0.923 to about 0.930
17 cm3, where ρ is the density of the blend, CρA and ρB are the densities of the linear low density polymer and the other polymer, and A and B are the densities used in the blend. It is a fraction of each of the polymers of it et al. Thus, the higher the density of the second polymer, the less of it should be used in the blend.

Alternatively, the second polymer in the blend has a density greater than one block of linear low density ethylene polymer. It can be polypropylene or a mixture of polypropylene and polyethylene or ethylene/α-olefin copolymers. When polypropylene or a mixture thereof is present and the layers are melted and manufactured in monolithic form by coextrusion, the linear low density ethylene polymer forms at least 250% by weight of the blend and the polypropylene accounts for 25ffi! of the blend! It is preferable to form a weight lee of 4 or less, more preferably 10 weight.

If desired, the blend may include small amounts of other compatible polymeric materials, such as low density polyethylene or ethylene copolymers, such as ethylene/vinyl acetate copolymers, but generally there is no leakage content of such materials. It is incredible to offer benefits and blends of about 20
In amounts greater than ~25% by weight, the polymeric phase can curl 7 when produced in melt form by single-layer coextrusion. In any case σ).

Such additional polymeric materials must be able to be processed at the temperatures required for extrusion of the blend when a coextrusion cut is used.

The other layer preferably provides the outer surface of the bag or pouch and is comprised of a linear low density ethylene polymer.

For best results, the density is preferably about 0.
916 to about 0.9251/Cm3. More preferably about 0
918 to about 0.922 g/cm3. It may also contain small amounts of other compatible plastic materials, such as low density or high density polymers or copolymers of ethylene, but this is not believed to be beneficial.

The coefficient of friction of the outer surface of the bag or large bag can be increased by mechanical and/or electrical treatment of the surface, such as a friction increasing additive,
For example, thickeners and/or thickeners can be added by applying rubbery polymers to the surface or, preferably, by incorporating such additives into the polymeric composition used for the production of the external layer. This can be achieved by doing so. However, there are some cases where additives are mixed in.

It is important that the surface thus obtained is not sticky to the touch. This is because it would otherwise interfere with the subsequent processing of a layer (or multiple layers, e.g. a coextruded film comprising said layers) in a bulk bag making machine and be uncomfortable when handled by one person. This is because it attracts garbage and dust. It is also necessary that the additive, when incorporated into the additive chip composition, be processable at the temperatures required for extrusion of the thermoplastic layer into which it is incorporated. Preferably, the required increase in the coefficient of friction is in Table 1.

This is achieved by including a polymeric component having blocking properties in the composition forming the layer providing the surface. Preferred examples of such polymers are generally amorphous polymers of olefins having at least 6 carbon atoms, especially isobutylene polymers, e.g.
It is polyisobutylene. Surprisingly, it is expected to be sticky to the touch, attract dirt, and be impossible to handle by automatic machinery. Considering the syrupy nature of such polymers, 1 molecular weight MW
[Polyethylene equivalent
Particularly good results have been obtained with isobutylene polymers in which the valent) ranges from about 500 to several thousand degrees. Satisfactory results may also be obtained with concentrations of this polymer not exceeding a few parts by weight.

For example, preferred isobutylene polymers have a weight ratio of 0.5 to 10 parts by weight, preferably 1 to 8 parts by weight, based on the thermoplastic material forming the layer incorporating the additive polymer.
More preferably 2 to 6% by weight, most preferably 2.5 to 6% by weight
It can be used in the armpits with 5% weight.

Preferably, the additive has a particle diameter of at least 0.8°, preferably at least 0.85°, as measured by ITM test 1)-1894 (static IF test). Most preferably at least 0
It is used with a friction coefficient of 87 and a yield of 7.

The lobo-remer composition used to form the two layers is:

Other additives commonly used with ethylene polymers, such as pigments, antioxidants and UV stabilizers, may also be included, but if one of the layers provides the inner surface of the bag or pouch, that layer The composition used for
It is particularly preferred to include a slip agent to reduce the coefficient of friction per surface as measured from ASTM 13-1894 (Static Test) V to preferably less than 0.5, more preferably less than 0.3. It's advantageous. This gives i
bags and large bags are easier to fill.

In one embodiment of the invention, at least one of the layers of the wall is infrared and/or This contains a UV absorber, such as carbon black, to prevent premature sprouting. Preferably, the inner layer (or the inner layer if the bag or large bag consists of more than two layers) is thus modified. , thereby.

The outer layer may, for example, be distinctly colored for appearance purposes.

It has been found that the bags or large bags of the present invention can be sutured using essentially the same automatic equipment as is commonly used with single paper large bags, but with It has been found advantageous to cover the area of the outer surface with a band of material having a lower coefficient of friction than said outer surface by means of an automatic bag handling machine, for example the shoe of a stitching machine. Ta. 1 bag of coating or a large bag.

Alternatively, it can be applied to the appropriate side of the film to form the bag or large bag. One convenient way of achieving this is to cover the area in question with a band of printing ink. This is because the coating can be carried out simultaneously with the desired inscription on the side of the bag, baglet or film.

Bags and large bags according to the present invention exhibit a combination of puncture resistance, tear resistance, burst resistance, tensile strength and low slippery outer surfaces, thereby making it acceptable for strong paper large bags, including multi-ply large bags. It can be used as a water substitute,
It has the above-mentioned capacity 2 which can exceed the stacking capacity 2 of large paper bags. Particularly good results are obtained when bags and pouches are made from the multilayer films of the invention, especially when the films are produced by coextrusion. These bags and large bags stack better than paper large bags.
t, and lack higher water resistance, improved printability and better germination prevention of the seed products packed in them, and can be sewn like paper bags. , or can be heat sealed and stored externally.

Bags and pouches or the films used for their manufacture can be perforated in known manner, for example for applications where the phase material stored therein perspires. Also, they can optionally lack a liner, and the liner can be plastic or other material, such as paper.

The ratio of the overall thickness of the bag or baglet wall and the thickness of the individual layers can be selected according to the intended end use. Generally, the total wall thickness is in the range of 25-200 microns, with a thickness of at least 140-150 microns generally required for heavy duty use. The ratio of the thickness of the layer formed from the linear low density polymer and the thickness of the layer formed from the blend is generally within the range of 5 to 50:50;
Higher dimensions for the first mentioned layer within this range are preferred for thinner overall wall thicknesses.

As a specific example, a black large bag is made from a tubular film having a total thickness of about 150 microns and formed by four-way extrusion of the first and second compositions. The first composition contains a slip agent, a carbon blank, and a polymer component, the polymer component being 0.
9245 g Ethylene copolymer (containing approximately 1.2 mole % hexene-1 and having a density of 25 tit coefficient σ) (calculated as above) of 7 cm and 0.
938 g/c, x3 and commercially available as liNA H1L501 from Petrofina) and 75 wt. Yes, 0.92
0. ! DOWLI (commercially available as X 2045) from the Dow Chemical Company
and this composition forms the inner layer of the tubular film. The polymer component of the second composition is UNIFUS from Unifos.
800<S and (13) a linear low density ethylene copolymer containing about 6 moles of Al and 1% butene and (13) about 4% isobutylene polymer [molecular weight MW in the range of about 1000-2000]. (polyethylene equivalent weight) and a broad molecular weight spread of from about 600 to about 6000], and the composition forms an outer layer about 38 microns thick.
child. The large bags have been found to be suitable as a replacement for multi-ply paper large bags, for example, for carrying loads of 25 kg of fertilizer and seed materials.

that in order to obtain large bags lacking similar properties of puncture resistance, yield strength and tear strength from low density polyethylene, the large bags need to have a wall thickness of 200 to 25 microns; In other words, it has been found that it is necessary to increase the number of kidnapping agents who request bribes by more than 66. Additionally, while the surface of a typical large bag has a coefficient of friction of about 0.5-0.6, in large bags made in accordance with the present invention, one shift on the outer surface is about 0.85-0. 87, resulting in significantly improved stacking properties. The coefficient of friction of the inner surface, on the other hand, was less than 0.5, which facilitated the filling of large bags.

40 inches x 48 inches (101,6CTrLX 12
1.9 CrrL) One ton of agricultural products packed in 40 large bags was loaded onto the Tubaret. These large bags were stacked in 5 layers with 5 large bags per layer. When using the large bag handles of the present invention, stacking is possible until one edge on each side is more than 20 inches (50.8 crrL) off the ground.

After tilting the pallet around one of its 48 inches (121,9 CrfL), it was still stable. When using large low-density polyethylene bags, the stacking capacity is 1 inch (4 filtration, 2 CrrL). Tie off the waste before tipping.

It was possible to achieve a tilt considerably lower than the usual 1 inch (4 finch, 2 α).

After several months of storage, there was no evidence of reduced friction or development of stickiness on the surface of the large bags of the present invention.

A method of forming a valve bag (rvalue lJag) according to the present invention.

This will be explained with reference to the accompanying drawings.

Referring to FIGS. 1 and 2, a bag 2 has a two-ply back wall 10 and a two-ply partially overlapping panel 12 and 1.
It is made from 4 and has a missing front wall. Panels 12 and 14
is integral with the back wall 10, which allows the lateral force seal 16
and 18 together form a flat two-ply tube closed at both ends. Panel 14 is panel 1
In the area that overlaps below 2, the free edge of the inner ply 20 protrudes a short distance beyond IJY to the freedom of the outer 1 law 22. Seal 24 joins both plies of panel 14 with the two plies of panel 12, and seal 26 joins the two plies of panel 12 with the projecting ends of ply 20. The left portion that is not sealed in a common area that overlaps at the top of the bag is delineated by the top of seals 24 and 26 together with seal 28 to form a tt 1.1 tubular valve sleeve. The protruding end of the inner ply 20 acts as a flap that closes when a bag is filled.

In another embodiment, outer ply 22 can protrude beyond inner ply 20. Furthermore, seal 2
6 is not required and seal 28 can be changed to a continuous seal. In yet other embodiments, the fourth
As illustrated in fig.

The outer ply 22 can extend over the panel 12 instead of under it. In other words, the portion of panel 12 that overlaps panel 14 is between ply 20 and ply 22.

The bag is formed by folding and sealing a flat film or a folded slit tubular film. The film has, in only a portion of its width, over at least a portion of one of its surfaces, a gap having a higher coefficient of surface friction than the outer surface of the film, said portion of width being the portion of the bag wall that provides an outer surface friction. . The width of the film that provides the inner surface of the bag has no such surface. Thus, in the embodiment illustrated in FIGS. 1 and 2, one bag is formed from a film consisting of a first layer 60 and a second layer 2. First layer 30 is one of two specified layers of the present invention.

The second layer 32 is the other of the two specified layers of the present invention and is in the form of a covering band for a portion of the width of said first layer that provides the outer surface of the bag walls i o , '12, and 14. be. This band is formed from a composition containing an additive such as a polymer of isobutylene (σ) which increases the surface coefficient of friction of the layer. Preferably, the first layer filter 0 is formed from a blend of polymers.

It is not necessary that all of the width of the first layer provided on the outer surface of the bag has said surface of higher surface coefficient of friction. For example, as illustrated in FIG.
0 and 12 external surfaces are provided.

In the embodiment illustrated in FIG.
The illustrated bag alternatively also forms two plies 40 and 42 and a first layer 0 and a second layer 62, with at least the outer ply 40 being the multilayer film of the present invention and the outwardly facing surface being the higher surface. It is a surface with a coefficient of friction of 7. The inner ply 42 may consist of the same film, in which case the surface with the lower coefficient of friction preferably faces inward, thereby forming the inner surface of the bag, or as shown in FIG. , T-pieces can be made of different films as long as they can be sealed to the outer ply 40 by heat sealing.

[Brief explanation of the drawing]

FIG. 1 is a side view of a bag made from a single ply of film. FIG. 2 is a sectional view taken along line A-AVc in FIG. 1. FIG. 6 shows a modification 7 of the bag of FIG. FIG. 4 is a cross-sectional view of a bag corresponding to FIG. 2 but of a different shape. FIG. 5 is a cross-sectional view corresponding to FIG. 2 of a bag similar in construction to the bags of FIGS. 1 and 2, but also formed with two separate plies. 2・・・・・・・・・・・・Bag 10・・・・・・・・・
2-ply base wall 12.14...Panel i6.
is...Seal 20...Inner ply 22...Outer ply 24.26
・・・・・・Seal 28・・・・・・・・・
Seal 30...First layer 6
2... Second layer filter 2A, 32B...
・・・Band AO・・・・・・Outer ply 4
2. Inner Ply Patent Applicant Intercontinental Plastics Incorporated Sodo Panama Branch Engraving of Drawings (Procedures for Making Changes to the Contents Amendment) Showa (July 7, 2017) 2. Name of the invention゛Las i fufurishini, 1.+1.father.) To 1. Dai T+'46, Relationship with the person making the amendment Patent applicant's address 4, Agent

Claims (1)

[Claims] 1. At least one of the walls includes a first layer and a second layer,
Each layer is formed by melt extrusion from a synthetic thermoplastic material;
and one of the layers comprises a linear low density ethylene polymer and (a) a selected second ethylene polymer having a higher density and an ethylene homopolymer and a copolymer of ethylene and at least one other alpha-olefin. at least one of a polymer and (bl polypropylene), and the other of said layers is comprised of a linear low density ethylene polymer, and at least one of said layers provides the wall surface and the outer surface of the wall. Thermoplastic bag or large bag, characterized in that at least a part of the surface has a higher coefficient of friction 7 than the inner surface. 2. The wall layers are fused together. A bag or large bag. 2. A bag or large bag according to claim 2, wherein the walls are formed from a coextruded thermoplastic film. 4. The other of the layers is an outer layer. Claims The bag or large bag according to any one of items 1 to 6. 5. The other linear low density ethylene polymer of the layer has a density in the range of 0.916 to 0.9251/CrrL3. The bag or large bag according to any one of claims 1 to 4. 6. The linear low density ethylene polymer in the other layer of the layer contains 0.918 to 0.922 g of The bag or large bag according to any one of claims 1 to 4 has a density in the range 2.Z The coefficient of friction of the outer surface of the wall is A8TM I)-1894.
(static test) of at least 0.8. A bag or large bag according to any one of claims 1 to 6. 8. The coefficient of friction of the outer surface of the wall is at least 085. A bag or large bag according to claim 7. 9. The coefficient of friction of the outer surface of the wall is at least 0.87. The bag according to claim 8 is a large bag. 10. Said one of said walls should form the innermost layer. A bag or large bag according to any one of claims 1 to 9. 11. The linear low density ethylene polymer used in the blend is a 1% copolymer of ethylene and a sulfur α-olefin having more than 4 carbon atoms.
A bag or one bag described in any of item 10 is a large bag. 12. The blend consists of a linear low density ethylene polymer and a second ethylene polymer having a higher density.
The bag bag according to any one of claims 1 to 11 is a large bag. 1, the second polymer weighs 0.930 to 0.935 g.
/cnL3. Claim 1
Bags or large bags described in Section 2. 14. Blend is about 0.914 to about 0.937 g/C
It has a density in the range of rIL3. Claim 11
．． The bag or large bag described in item 12 or 13. 15. Blend is about 0.92Cl to about 0.955 g
/cm, density in the range of 3 to 1. A bag or large bag according to claim 14. 16. Blend is about 0.923 to about 0.930,! 9
/cm3. Claim No. 15
Bags or large bags as described in section. The inner surface of the IZ wall 6t has a coefficient of friction less than 60.5 as measured by ASTM L)-1894 (static test). A bag or large bag according to any one of claims 1 to 16. 18. It is a valve bag. A bag or large bag according to any one of claims 1 to 17. 19, as substantially hereinafter described with particular reference to the Examples. The bag according to claim 1 is a large bag. 20, a laminate comprising at least two layers, each layer σ) formed by melt extrusion from a synthetic thermoplastic H material, and the first of the layers comprising a linear low density a blend of an ethylene polymer and a second ethylene polymer (having a higher density than al and selected from ethylene homopolymers and copolymers of ethylene and at least one other alpha-olefin) and tb+ polypropylene; A second of said layers comprises a linear low density ethylene polymer, at least one of said layers provides a surface of the multilayer film, and at least a portion of the surface of one side is higher than the other side of the film. 21. The multilayer film according to claim 20, formed by coextrusion and having a surface friction coefficient of 1%. 22. The multilayer film according to claim 20, formed by inflation. The multilayer film according to claim 21. 26. The multilayer film according to any one of claims 20 to 26, wherein the first layer and the second layer are film surfaces. 24. Linear low density ethylene. In the layer which also comprises a polymer, said polymer has a density specified in claims 5 or 6 of 1%.
The multilayer film according to any one of paragraphs Jt. 25, a layer consisting of a linear low density ethylene polymer. Provides intermittent film with higher surface friction coefficient. A multilayer film according to any one of claims 20 to 24. 26. The friction coefficient is defined in claims 7 to 9 σ)
There is only one thing that can be specified in any of it. A multilayer film according to claim 25. 27. Blend is defined in any one of claims 11 to 16. Claim 2
The multilayer film according to any one of items 0 to 26. 28. A multilayer film according to any one of claims 20 to 28, characterized in that the layer consisting of the blend is the other layer of the film. 29, and (substantially described below with reference to Examples). A multilayer film according to any one of claims 20 to 28. 30, A multilayer film according to any one of claims 20 to 29. A bag or large bag formed from the described multilayer film.