KR101162096B1 - Multi-layer film - Google Patents

Abstract

The present invention relates to a composite multilayer film, more specifically, an inner layer; And an outer layer, wherein the inner layer comprises low density polyethylene and linear low density polyethylene, and the outer layer provides a composite multilayer film comprising polypropylene. The inner layer preferably further comprises an anti-blocking agent (and / or slip agent) for improving the openness and / or an antistatic agent for antistatic. According to the present invention, it has an effect of excellent sealing properties when processing into a packaging agent. In addition, it has excellent opening property (opening property) and antistatic ability to facilitate automatic packaging and continuous packaging operations.

Multilayer, Film, Inner Layer, Outer Layer, Sealing, Packing, Pouch

Description

Composite Multilayer Film {MULTI-LAYER FILM}

The present invention relates to a composite multilayer film, and more particularly, to a composite multilayer film having excellent sealing properties and opening properties.

In general, various products essential for daily life, such as powdered detergents, shampoos, fabric softeners, starch powder, powdered coffee, and the like are packaged in soft packaging films. At this time, the film is composed of a multilayer of two or more layers. For automatic packaging, the inner layer, that is, the sealing layer, should be made of a material having good low temperature sealing properties.The outer layer, which is in contact with the outside air, has a sealing temperature (melting temperature) of at least 30 ℃ higher than that of the inner layer (sealing layer). Should be high. When the temperature difference (ΔT) between the inner layer and the outer layer is 30 ° C. or more, the inner surfaces are thermally bonded by the heat applied from the outer layer when the product is packaged, and the outer surfaces are prevented from being thermally bonded to seal the M or W shape.

Conventionally, in manufacturing a composite multilayer film, a polyethylene (PE) film and a polyethylene tephthalate (PET) film (or a stretched nylon film) are prepared separately, and then manufactured through dry lamination using a solution adhesive. have. In addition, the outer layer film is subjected to a printing process for displaying the content of the contents or the publicity effect. Specifically, the PE film and the PET film are prepared separately, and then the PET film is printed, and then an adhesive is applied between the PE film and the PET film. The solvent is evaporated below 50 ° C. through a dry process, and left at least 12 hours in an aging room below 60 ° C. At this time, the PE film and the PET film are laminated while the adhesive is crosslinked.

However, the lamination method using the solution-type adhesive as described above has a problem in that environmental hormones harmful to the human body are not only detected due to residual solvents such as toluene, isopropyl alcohol, acetic acid, but also the price of the product is increased by a complicated product production process.

In addition, it is preferable to use polyethylene and polypropylene in preparing a composite multilayer film, but it is known in the art that polyethylene is not attached to polypropylene without adding an additive for bonding or modifying polyethylene. . For example, a document published in Science, vol. 288, p2187, 2000 states that polyethylene (PE) and polypropylene (PP) do not adhere to each other.

Polypropylene is difficult to extrude in blown film processing as well as in expensive double bubble forming pores. Therefore, it is desirable to include polyethylene to promote extrusion of polypropylene in blown film applications. At this time, the sealing property at the time of packaging should be ensured.

In addition, when packaging the contents, soft packaging should be easily opened. In other words, the inner layers that are in close contact with each other should be easily opened to enable automatic packaging.

However, the composite multilayer film according to the prior art has a problem in that the sealing property, that is, the heat adhesive strength is inferior. In addition, there is a problem that automatic packaging is difficult because of the openness (opening). In addition, it is pointed out that the film according to the prior art is poor in continuous packaging workability due to the generation of static electricity.

The present invention is to solve the problems of the prior art as described above, to provide a composite multi-layer film that is laminated (attached) by coextrusion of polyethylene and polypropylene without using a binder, and excellent in sealing properties There is a purpose.

In addition, an object of the present invention is to provide a composite multi-layer film having excellent opening property (opening property) and / or antistatic property, which is easy for automatic packaging and continuous packaging operation.

The present invention to achieve the above object,

An inner layer comprising low density polyethylene and linear low density polyethylene; And

Provided is a composite multilayer film comprising an outer layer comprising polypropylene.

The inner layer further comprises an anti-stick agent for improving the openness and / or an antistatic agent for antistatic, according to a preferred embodiment. The anti-adhesion agent is selected from, for example, an anti-blocking agent, a slip agent, or the like, which forms surface irregularities and the like.

In addition, an intermediate layer including, for example, polypropylene may be further formed between the inner layer and the outer layer.

According to the invention, the inner layer comprises a blend of low density polyethylene and linear low density polyethylene, which has an effect of excellent sealing properties. In addition, the inner layer and the outer layer are laminated (attached) by coextrusion. In addition, in the case of further comprising an anti-adhesion agent and / or an antistatic agent, the opening property (opening property) and the antistatic ability are excellent, so that the automatic packaging and continuous packaging operation can be easily performed.

Hereinafter, the present invention will be described in detail.

The composite multilayer film according to the present invention comprises at least an inner layer and an outer layer. At this time, the inner layer is in contact with the contents, and the outer layer is in contact with the outside air.

The inner layer includes Low Density Polyethylene (hereinafter referred to as "LDPE") and Linear Low Density Polyethylene (hereinafter referred to as "LLDPE"). Specifically, the inner layer is molded from a composition comprising at least a blend of LDPE and LLDPE.

According to the invention, the inner layer comprises a blend of LDPE and LLDPE, and has excellent sealing properties. Specifically, the LDPE improves the mechanical properties of the inner layer, and the LLDPE is melted by the low temperature heat applied in the outer layer to effectively improve the low temperature sealing property. At this time, although not particularly limited, LDPE and LLDPE may be blended in a weight ratio of 1 to 8: 9 to 2 (LDPE: LLDPE = 1 to 8: 9 to 2). For example, LDPE and LLDPE may be blended in a weight ratio of 1 to 5: 9 to 5 (LDPE: LLDPE = 1 to 5: 9 to 5). If the content of the LDPE is too low outside the range, the mechanical properties of the inner layer may not be good, and if the content of the LDPE is too high outside the range, the content of LLDPE is relatively low, the strength may be weakened at low temperature sealing. . In addition, the inner layer may include polypropylene (PP) or additives as needed, in addition to the blend of LDPE and LLDPE, wherein the blend of LDPE and LLDPE may occupy 40% by weight or more of the total weight of the inner layer.

The LDPE may have a density of 0.890 to 0.970 g / cm 3 as a low density. For example, the LDPE may have a density of 0.910 to 0.930 g / cm 3. In addition, the LDPE, for example, when the film is manufactured by blow molding through co-extrusion, a melt index (M.I) at 190 ° C. may be 0.1 to 10 g / 10 minutes. More specifically, the melt index (M.I) of the LDPE can be used that is 1.0 to 5g / 10 minutes. Melt index (M.I) in the present invention is in accordance with the standard test method ASTM D 1238.

In addition, when the film is manufactured by blow molding through coextrusion, the molecular weight distribution (MWD; Molecular Weight Distribution) of the LDPE is preferably 1.0 to 4.0. At this time, if the molecular weight distribution (MWD) of the LDPE is less than 1.0, the extrusion load is high or the bubble stability is poor during processing, and if the molecular weight is greater than 4.0, the polymer may have a low molecular weight and the opening property may be decreased, and the tensile strength and impact Mechanical properties such as strength may deteriorate.

The LLDPE may have a density of 0.860 to 0.970 g / cm 3 as a low density, and more specifically, may have a density of 0.910 to 0.930 g / cm 3. In addition, the LLDPE, for example, when the film is produced by blow molding through co-extrusion, a melt index (MI) at 190 ° C. may be used in a range of 0.1 to 10 g / 10 minutes, and more specifically, The thing of 0.5-3 g / 10min can be used.

In addition, when the film is prepared by blow molding through coextrusion, the molecular weight distribution (MWD) of the LLDPE is preferably 0.9 to 2.0. In this case, when the molecular weight distribution (MWD) of LLDPE is less than 0.9, bubbles may be severe during processing, and wrinkles may occur in the film. When the molecular weight distribution (MWD) is greater than 2.0, the polymer may have a low molecular weight, and thus the opening property may be deteriorated. And mechanical properties such as impact strength may be degraded.

In addition, the LLDPE is not particularly limited, but one or more selected from the group consisting of butene-LLDPE, octene-LLDPE, hexene-LLDPE, and the like may be used. At this time, when LLDPE is selected from octene-LLDPE, hexene-LLDPE, etc. among those listed above, low temperature sealing property becomes more excellent.

According to a preferred embodiment, the inner layer further comprises an anti-adhesion agent. Specifically, the inner layer may include at least a blend of LDPE and LLDPE, but may be molded from a composition further comprising an adhesion inhibitor. At this time, the adhesion inhibitor is for opening (opening), and any thing that can facilitate the opening at the time of packaging the contents by interfering the adhesion with other adjacent surfaces (for example, adjacent inner layer surface). Any use is available. The anti-sticking agent may use one or more selected from the group consisting of an anti-blocking agent and a slip agent. At this time, the adhesion inhibitor is not particularly limited, but may be included in the inner layer at 20% by weight or less. For example, the anti-blocking agent may be included in the inner layer 10% by weight or less, specifically 100ppm to 10% by weight, the slip agent may be included in the inner layer 10,000ppm or less, specifically 100ppm to 5,000ppm, It is not limited to this.

The anti-blocking agent is to prevent the adhesion between the inner layer surface and the like by forming irregularities on the surface of the inner layer, for example, silica (SiO _2, etc.), zeolite (Zeolite), calcium carbonate (CaCO ₃ ) one or more selected from the group consisting of inorganic powders such as talc and talc, may be used, but is not limited thereto.

In addition, the slip agent is to prevent slipping by improving the slipperiness on the surface of the inner layer, for example, selected from the group consisting of erucamide, oliamide, stearamide, and the like. One or more may be used, but is not limited to these. At this time, the purchase of the slip agent is various, the erucamide (Arucamide), for example, Akzo Nobel Armoslip-E products, the oliamide (Oliamide) for example Armoslip-CP Products, and the stearamide (Stearamide) can be used, for example, Akzo Novel Armoslip-HT products.

In addition, the inner layer may further include an antistatic agent. Specifically, the inner layer includes at least a blend (and anti-adhesion agent) of LDPE and LLDPE, but may be molded from a composition further comprising an antistatic agent. In this case, the antistatic agent may be used as long as it has an antistatic property, for example, at least one elected from the group consisting of ester-based, glycerin monostearate (GMS) -based, amine-based and amide-based compounds, etc. An inhibitor can be used. The antistatic agent may be included in an inner layer of 10,000 ppm or less, specifically, 100 ppm to 3,000 ppm, but is not limited thereto.

In addition, the inner layer may further include one or more additives selected from antioxidants and light stabilizers as other additives. In addition, the inner layer may further include a color material (color pigment or dye) as necessary to implement a variety of colors. As the color material, inorganic pigments such as titanium dioxide (TiO ₂ ) may be used.

The outer layer has a higher sealing temperature (melting temperature) than the inner layer, for example, at least 30 ° C or higher. The outer layer comprises polypropylene (PP). The outer layer preferably comprises polypropylene (PP), which may comprise at least 30% by weight of the total weight of the outer layer. In this case, the polypropylene (PP) includes homo polypropylene (homo PP), block polypropylene (block PP) and random polypropylene (random PP). In addition, the polypropylene (PP) is not limited in density, and the melt index (MI) is 0.3 to 25 g / 10 at 230 ° C. when the outer layer is manufactured, for example, by blow molding through coextrusion. Powder (ASTM D 1238) can be used. More specifically, the polypropylene (PP) may be a melt index (MI) at 230 ℃ 0.4 to 20g / 10 minutes (ASTM D 1238), more specifically 0.5 to 5g / 10 minutes Homo polypropylene (homo PP) having a melt index (MI) of (ASTM D 1238) can be used.

In addition, the outer layer may further include an antistatic agent. Specifically, the outer layer includes at least polypropylene (PP), but may be molded from a composition further comprising an antistatic agent. At this time, the antistatic agent is as described above. That is, the antistatic agent may use one or more antistatic agents selected from the group consisting of ester-based, glycerin monostearate (GMS) -based, amine-based, and amide-based compounds. And the antistatic agent may be included in the outer layer 10,000 ppm or less, specifically 100ppm to 3,000ppm, but is not limited thereto. In addition, the outer layer may further include one or more additives selected from antioxidants, light stabilizers, and the like as other additives, and various colors may be implemented by further including color materials (color pigments or dyes) as necessary. .

In addition, the outer layer may be corona treated. Corona treatment is good at the time of the printing process for the indication of the content of a content, the publicity effect, etc. That is, when the surface of an outer layer is corona-treated, printability (ink absorption etc.) improves. Although the said corona treatment is not specifically limited, It can carry out with the intensity | strength of 35 dyne or more.

The composite multilayer film according to the present invention has a multilayer structure of at least two layers, including an inner layer and an outer layer as described above. At this time, as described above, the inner layer includes a blend of LDPE and LLDPE and has excellent low temperature sealing property with mechanical properties. That is, it is easily melted at low temperatures while ensuring good mechanical properties (tensile strength, etc.), and high sealing strength (heat adhesion strength). In addition, when the inner layer further contains an anti-sticking agent, the opening property (opening property) is improved to facilitate automatic packaging. In addition, when the inner layer (and / or outer layer) further includes an antistatic agent, workability is improved to facilitate continuous packaging operation.

The composite multilayer film according to the present invention may further include at least one intermediate layer formed between the inner layer and the outer layer, and may have a three-layer or four-layer composite multilayer structure. In this case, the intermediate layer may be selected from a resin layer and a metal thin film layer. The resin layer is not particularly limited as long as the melting temperature is higher than that of the inner layer. For example, the resin layer may be selected from polypropylene (PP), polyethylene terephthalate (PET), and the like. The metal thin film layer is not particularly limited, but may be selected from, for example, aluminum (Al) or an aluminum alloy thin film layer. In addition, the intermediate layer may include a color material and various colors may be implemented, and other additives may be included. In addition, if the outer layer is close to transparent, the intermediate layer may be laminated with the outer layer after the printing for the component display or promotion of the contents.

In addition, the composite multilayer film according to the present invention may be prepared by coextrusion or laminating. Specifically, the inner layer and the outer layer may be co-extruded and laminated integrally while blowing is carried out through a co-extruder, and may also be laminated separately by thermal fusion after each separately manufactured. It is preferably manufactured through co-extrusion, which is advantageous in the manufacturing process, defective rate and manufacturing cost. In this case, the co-extrusion may be carried out using a co-extruder having at least two extruders (first extruder, second extruder, etc.), while blowing gas such as air while co-extruded at a temperature of 120 ℃ or more. In addition, when the expansion ratio (B.U.R; Blow Up Ratio) at the time of coextrusion is too small or large, wrinkles may occur in the film or the film thickness may not be constant. Therefore, the expansion ratio (B.U.R) may be set to 1.0 to 4.0.

Composite multilayer film according to the present invention described above can be usefully used as a packaging agent. The composite multilayer film according to the present invention is used, for example, as a packaging agent for detergents, shampoos, fabric softeners, starch powder, coffee, clothing, stationery, electronic products, and the like. More specifically, it may be usefully used as a stand-up pouch such as M-shaped, W-shaped, T-shaped as a soft packaging agent.

Hereinafter, the Example and comparative example of this invention are illustrated. The following examples are merely provided to aid the understanding of the present invention, whereby the technical scope of the present invention is not limited.

[Examples 1 to 6]

To prepare a film of a three-layer structure having an inner layer, an intermediate layer and an outer layer, the raw material of the inner layer, intermediate layer and outer layer was prepared by different compositions (components and contents) according to each embodiment as shown in Table 1 below. . In this case, the extruder is a three-layer blown type coextruder, but the cylinder temperature of the first extruder is set to 160 ℃ of the processing conditions, the cylinder of the second and third extruders The temperature was set to 180 ° C. and worked. In addition, the blow up ratio during coextrusion was set to 2.2. The specification of the extruder is as follows. In addition, after extrusion, the outer layer was subjected to corona treatment selectively according to each example.

<Extruder Specification>

Die Diamater: Φ 500㎜

-1st extruder (inner layer): Φ 60㎜ Extruder

-2nd extruder (middle layer): Φ 70mm Extruder

-3rd extruder (outer layer): Φ 60㎜ Extruder

[Comparative Examples 1 and 2]

In the same manner as in Example 1 except that the raw materials of the inner layer, the middle layer and the outer layer were prepared by different compositions (components and contents) as shown in Table 1 below.

Remarks Composition and content of each layer Film specimen
thickness Outer layer
corona
Processing strength Inner layer Mezzanine Outer layer Example 1
LD / LLD Blends Homo PP sole Homo PP sole 100 ± 5㎛ No treatment Example 2
LD / LLD Blends Random PP sole Homo PP sole 100 ± 5㎛ 38 dyne Example 3 LD / LLD Blends
1500ppm made of A / B
Slip 600ppm Homo PP 97% by weight
3% by weight of color pigment Homo PP sole 100 ± 5㎛ 38 dyne Example 4 LD / LLD Blends
1500ppm made of A / B
Slip 600ppm
Charging agent 1000ppm Block PP alone Homo PP sole 100 ± 5㎛ 38 dyne Example 5 LD / LLD Blends
1500ppm made of A / B
Slip 600ppm
Charging agent 1000ppm Homo PP 97% by weight
3% by weight of color pigment Homo PP
Charging agent 1000ppm 100 ± 5㎛ 38 dyne Example 6 LD / LLD Blends
1500ppm made of A / B
Slip 600ppm Homo PP sole Homo PP sole 100 ± 5㎛ 38 dyne Comparative Example 1
LD / LLD Blends LD sole LLD only 100 ± 5㎛ No treatment Comparative Example 2
LD sole Homo PP sole Homo sole 100 ± 5㎛ 38 dyne (1) LD: Nonlinear low density polyethylene (LDPE), which has a melt index (MI) of 3.0 g / 10 min (at 190 ° C.), a density of 0.920 g / cm 3, and a molecular weight distribution (MWD) of 2.2.
(2) LLD: Linear low density polyethylene (LLDPE), which has a melt index (MI) of 1.0 g / 10 min (at 190 ° C.), a density of 0.920 g / cm 3, and a molecular weight distribution (MWD) of 1.2.
(3) LD / LLD blend: LD and LLD blended at a weight ratio of 3: 7
(4) PP: Polypropylene, using a product having a melt index (MI) of 1.0 g / 10 min (at 230 ° C) and a density of 0.920 g / cm 3
(5) A / B agent: SiO _{2 is} used as anti-blocking agent
(6) Slip: Erucamide is used as a slip agent (Purchased: Akzo Nobel, Armoslip-E)
(7) Antistatic agent: Use of ester type antistatic agent as antistatic agent
(8) Color Pigment: TiO ₂ used

After processing the film specimens according to the Examples and Comparative Examples prepared as described above to M-shaped pouch, to find out the suitability as a packaging agent as follows (sealing strength), antistatic (half-life), dog The structure (openability) and printability were evaluated, and the result is shown in the following [Table 2].

< Sealing ( Sealing  Strength) measurement>

After sealing, after 24 hours, when the sealing surface is pulled (ASTM D 882), if the load value to be separated is more than 700g, "good", if more than 100g less than 700g "weak", less than 100g Or when M-shaped machining was not possible, "bad" was evaluated.

<Antistatic (half-life) measurement>

After applying a voltage of 6KV to the film surface for 30 seconds, it was evaluated by the time (half life) until the surface resistance value decreased by 50%. (The shorter the half life, the better the antistatic property).

< Openness (Openability)>

When the overlapped film was rubbed by hand, it was evaluated as "good" if it was easily separated and "bad" if not separated.

<Printability>

The printing state was visually observed and evaluated as "good" if clear, and "bad" if bleeding was observed or not clear.

Remarks Sealing
(Sealing strength) Inner layer antistatic
(Half life time) Inner layer antistatic
(Half life time) Openness
(Openability) Printability Example 1 Good 20 minutes or more 20 minutes or more Bad Bad Example 2 Good 20 minutes or more 20 minutes or more Bad Good Example 3 Good 20 minutes or more 20 minutes or more Good Good Example 4 Good Within 1 minute 20 minutes or more Good Good Example 5 Good Within 1 minute Within 1 minute Good Good Example 6 Good 20 minutes or more 20 minutes or more Good Good Comparative Example 1 Poor (impossible) 20 minutes or more 20 minutes or more Bad Bad Comparative Example 2 weakness 20 minutes or more 20 minutes or more Bad Good

As shown in Table 2, the inner layer includes a blend of LDPE and LLDPE, and the outer layer includes PP having a higher melting temperature than the inner layer (1 to 6). It turned out that sealing property (sealing strength) is favorable. In the case of Comparative Example 2, which used LDPE alone as the inner layer, the sealing property (sealing strength) was weak. In Comparative Example 1, which used LLDPE alone as the outer layer, the temperature difference between the inner layer and the outer layer was lower than 20 ° C. It was found impossible.

In addition, when the A / B agent and the slip agent were added (Examples 3 to 6) as the adhesion inhibitor, it was found that the opening property (opening property) was good. This means that automatic packaging is easy.

In addition, it was found that when the antistatic agent was added (Examples 4 to 5), the generation of static electricity was prevented (surface resistance decrease). This means that continuous automatic packaging is easy.

Moreover, when corona treatment was performed to the outer layer, it turned out that printability becomes favorable.

In particular, as in Example 5, the inner layer is a blend of LDPE and LLDPE, the main component, an antistatic agent and a slip agent is added, and the sealing property (sealing strength), the internal / outer layer antistatic property, opening (opening) And all the physical properties such as printability is good, it can be seen that it is very useful for packaging containers such as M-shaped.

Claims (13)

Low density polyethylene with a density of 0.890 to 0.970 g / cm 3 and a melt index (MI) at 190 ° C. of 0.1 to 10 g / 10 min and a density of 0.860 to 0.970 g / cm 3 and a melt index (MI) at 190 ° C. of 0.5 An inner layer of linear low density polyethylene blended at a weight ratio of from 1 to 8: 9 to 2, ranging from 10 to 10 g / 10 min; And A composite multilayer film comprising an outer layer comprising polypropylene. delete delete The method of claim 1, The inner layer further comprises one or more selected from the group consisting of anti-blocking agents and slip agents. 5. The method of claim 4, An anti-blocking agent is a composite multilayer film, characterized in that at least one selected from the group consisting of silica, zeolite, calcium carbonate and talc (Talc). 5. The method of claim 4, The slip agent is a composite multilayer film, characterized in that at least one selected from the group consisting of erucamide (Erucamide), oliamide (Oliamide) and stearamide (Stearamide). The method of claim 1, Inner layer is a composite multilayer film, characterized in that further comprises an antistatic agent. The method of claim 1, The outer layer is a composite multilayer film, characterized in that the melt index (M.I) is 0.3 to 25g / 10 minutes. The method of claim 1, The outer layer is a composite multilayer film, characterized in that further comprises an antistatic agent. The method of claim 1, A composite multilayer film formed between an inner layer and an outer layer, further comprising an intermediate layer comprising polypropylene. The method according to claim 7 or 9, Antistatic agent is a composite multilayer film, characterized in that at least one selected from the group consisting of ester-based, glycerin monostearate (GMS), amine-based and amide-based. The method of claim 1, Composite multilayer film, characterized in that the inner layer and the outer layer is coextruded. The method of claim 1, Composite multilayer film is a composite multilayer film, characterized in that used as a soft packaging agent.