JP3160221B2 - Polyethylene multilayer film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene-based multilayer film laminated on a base film as a sealant film, and more particularly to a dry laminate product using all adhesives including a polyether-based polyurethane adhesive. The bag-made product has extremely good blocking resistance, openability and slipperiness. Even after the bag-made product has been stored for a long time throughout the summer, the inner surfaces of the bag-made product do not adhere to each other, and dry lamination processing The present invention relates to a well-balanced polyethylene-based multi-layer film which significantly reduces deposition on various rolls due to a slip agent, has excellent sealability, and has improved scratch resistance due to friction between sealant films.

[0002]

2. Description of the Related Art At present, in the field of food packaging, biaxially stretched nylon films, biaxially stretched polyester films, biaxially stretched polypropylene films, and the like, which have relatively high gas barrier properties and moisture proofness, and have high strength, are used. I have. However, these base films have a high melting point and are inferior in heat sealability. Therefore, it is necessary to laminate a sealant film in order to provide heat sealability. Such sealant films include high-pressure low-density polyethylene and ethylene / α-olefin copolymer (L-LDP).
E), a film mainly using a polyolefin-based resin such as an ethylene / vinyl acetate copolymer or polypropylene is used. Among them, ethylene / α-olefin copolymer film is excellent in transparency, seal strength, hot tack property, impact resistance, sealing property for impurities, etc.
Particularly high seal strength is not found in other polyolefin resins, and is widely used as a sealant film. Further, as a method of laminating the sealant film on the base film, there are a dry lamination method and an extrusion lamination method. Among them, the dry lamination method is widely used because it has excellent adhesive strength.

[0003] Among the properties required for the sealant film, the opening property is a very important property from the viewpoint of improving workability. Here, the opening property refers to the degree of opening of the bag after the dry-laminated film is applied to a bag making machine to produce a three-side seal bag. With a three-sided seal bag, only the upper or lower part for filling is left as an opening,
Refers to a bag heat-sealed in a U-shape. If the opening property is good, the bag is already opened at the time of filling the contents, which is a process after the bag making, and the workability is very good. Conversely, if the inner surfaces of the bags are in close contact with each other, it takes time to open the bags, and the workability is extremely poor.

By the way, the opening property tends to be particularly poor when a polyether-based polyurethane adhesive is used as the dry laminate adhesive. This adhesive has the characteristics of higher initial adhesive strength, faster curing, and lower cost as compared with the polyester-based polyurethane adhesive, but it has a characteristic of 30 to 60 ° C. for 1 to 4 days to accelerate the curing of the adhesive. When aging is performed on a day, there is a disadvantage that the higher aliphatic amide-based slip agent blended in the film is absorbed by the adhesive and deteriorates the opening property.

In order to improve such disadvantages, for example, a combination with a slip agent which is hardly absorbed by a dry laminating adhesive has been proposed (JP-A-51-7404, JP-A-3-172328). However,
According to this method, although the slip property is improved, it is possible to satisfy both the adhesion of the slip agent to the laminating roll at the time of dry lamination, the opening property of the bag after bag making, and the abrasion resistance of the sealant films. Did not.

There is also a report that the use of a high-density polyethylene resin can eliminate sticky components and improve the opening property. However, since the heat-sealing start temperature is increased, it is practically used as a sealant film. Is not good.

The present inventors have previously proposed a polyethylene-based multilayer film which does not have such a disadvantage (Japanese Patent Laid-Open No. 6-3).
12491). The film has improved slip agent adhesion to a laminating roll at the time of dry lamination, good transparency, and good abrasion resistance with good slipperiness and opening property of the film after bag making. However, the opening properties sometimes deteriorated depending on the storage conditions. For example, when the temperature of a storage place in summer or the temperature during transportation becomes high, the opening property immediately after bag making is good, but the opening property after long-term storage (for example, about 6 months) may be significantly deteriorated. Was.

[0008]

SUMMARY OF THE INVENTION The present invention does not have the above-mentioned drawbacks. In a dry laminate containing a polyether-based polyurethane adhesive, the deposition on various rolls due to a slip agent during processing is greatly reduced. Is a well-balanced film with excellent blocking resistance and slipperiness, and excellent scratch resistance and sealing suitability, as well as good openability after bag making. Even when stored under severe conditions for a long time,
For example, it is an object of the present invention to provide a polyethylene-based multi-layer film which is excellent in opening properties without sticking of bag-made products even after long-term storage throughout the summer.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that the blending of a specific polyethylene resin, fine particles, and a slip agent achieves the object of the present invention. The inventors have found that the use of a multilayer film can improve the transparency and cost because the amount of fine particles to be added can be reduced, thereby completing the present invention. That is, the present invention relates to a polyethylene-based multilayer film composed of an A layer mainly composed of a polyethylene resin and a B layer mainly composed of a polyethylene resin, wherein the A layer has the following composition and Polyethylene-based multilayer in which the blocking strength between the A-layers at 60 ° C. of a film obtained by dry laminating the corona-treated surface of the B-layer of the multilayer film with the base material using a polyether-based polyurethane adhesive is 0.1 kg / 25 cm ² or less at 60 ° C. Provide a film. 100 parts by weight of a copolymer of the following ethylene and an α-olefin having 4 to 10 carbon atoms (1) Gel permeation chromatography (hereinafter, referred to as
Abbreviated as GPC. ) (Weight average molecular weight (hereinafter abbreviated as Mw)) / number average molecular weight (hereinafter abbreviated as Mw).
Abbreviated as Mn. )) Is not less than 1.8 and not more than 3.2 (2) Separation by temperature rise elution (hereinafter abbreviated as TREF)
3% or less at 50 ° C. (3) After complete melting, the solution was gradually cooled, and then the differential scanning calorimeter (hereinafter, referred to as
Abbreviated as DSC. )), Two or more absorption peaks are 100 ° C or higher and 1 or more.
Below 20 ° C., in which one or more peaks
At least 110 ° C. and less than 120 ° C. (4) Density is 0.900 to 0.940 g / cm ³ (5) Melt flow rate (hereinafter abbreviated as MFR) .)
Is 1 to 10 g / 10 min, the average particle size is 11 to 20 μm, and the decomposition start temperature of the particles is 2
0.3 to 2.0 parts by weight of polymer fine particles having a temperature of 50 ° C. or higher 0.02 to 0.07 parts by weight of unsaturated fatty acid amide 0.01 to 0.20 parts by weight of unsaturated fatty acid bisamide

[0010] The substrate in the present invention refers to a substrate on which a sealant film is laminated, and specific examples thereof include a biaxially stretched nylon film, a biaxially stretched polyester film, and a biaxially stretched polypropylene film. it can.

Hereinafter, the present invention will be described in detail. The film of the present invention has at least two or more layers. Where A
The layer is a seal layer, the B layer is a dry laminate layer with another base material, and when there are three or more layers, all layers other than the A layer are B layers. It is preferable that the thickness ratio of layer A / layer B is 1/1 to 1/6. When the A layer is 1/1 or more, the transparency is deteriorated. Meanwhile, 1
If it is / 6 or less, the blocking resistance tends to deteriorate, which is not preferable. By making the thickness ratio A layer / B layer in a multilayer film of two or more layers 1/1 to 1/6, the transparency can be improved by reducing the amount of additives, and the cost can be reduced.

As the layer A of the present invention, a polyethylene resin satisfying the following conditions is used. (1) The molecular weight distribution (Mw / Mn) by GPC is 1.8.
Not less than 3.2 or less. When the ratio is less than 1.8, the opening property, the blocking resistance, and the slipping property are good, but when a film is actually formed, the resin pressure of the extruder increases due to the narrow molecular weight distribution, and the production amount is increased. There is a drawback that can not be raised. on the other hand,
When it is larger than 3.2, since the content of the low molecular weight is large, the blocking resistance and the slipperiness are inferior, and the opening property is deteriorated.

(2) The elution amount at 50 ° C. in TREF is 3% or less. If it is 3% or more, the amount of the low-melting-point extract increases, and the blocking resistance and the opening property deteriorate. In addition, TREF and the above-mentioned Mw and Mn were measured as follows. First, the polymer to be measured is completely melted in o-dichlorobenzene at 140 ° C. Thereafter, cooling is performed to form a thin polymer layer on the surface of the inert carrier (TREF column).
Next, when the temperature is continuously or stepwise increased, in a low temperature stage, the polymer is eluted from an amorphous portion in the target polymer composition, that is, a polymer having a high degree of short-chain branching having a polymer,
As the temperature rises, the one with a low degree of branching elutes gradually, and finally the linear part without branching elutes. The concentration of the eluted component at each of these temperatures is detected, and the composition distribution of the polymer is measured by a graph drawn based on the amount of the eluted and the elution temperature. Simultaneously eluted components are analyzed by gel permeation chromatography to determine molecular weight and molecular weight distribution. The measuring device used was a cross-separating device (CFC T150A manufactured by Mitsubishi Yuka Co., Ltd.). The measurement conditions are as follows. Dissolution volume: 1 ml / min, measured concentration: 4 mg / ml, GPC column: AD80M / S × 3, manufactured by Showa Denko, cooling rate: 1 ° C./min, injection volume: 200 μl

(3) In the thermogram obtained by DSC, two or more absorption peaks are at 100 ° C. or more and less than 120 ° C., and one or more peaks are 100 ° C. or more and 1
<10 ° C., one or more remaining peaks at 110 ° C.
It is above 120 ° C. Blocking resistance, opening property,
A condition that balances the sealing temperature and the bag making efficiency in automatic packaging is to have two specific peaks. In other words, low-temperature sealability can be obtained by giving the lower peak an absorption peak of 100 ° C. or higher and lower than 110 ° C.
Good blocking resistance and openness can be obtained at the absorption peak at 110 ° C. or higher and lower than 120 ° C., which is the higher peak.
Here, the absorption peak is ASTM: D3417-82.
Scanning calorimeter (DS, manufactured by Seiko Instruments Inc., based on
(C-200). For the measurement, 9 mg of a sample formed into a sheet having a thickness of 0.5 mm was held at 210 ° C. for 10 minutes, then the temperature was decreased to 30 ° C. at a rate of 10 ° C./min, and then increased at a rate of 10 ° C./min. The melting curve obtained by heating was recorded on a chart paper, and the temperature at which the maximum value was obtained was measured. In the present invention, the term “peak” refers to a peak that clearly shows a maximum on the endothermic side, and has a shoulder (shoulder).
The shape is not a peak. (4) Density: 0.900 to 0.940 g / cm ³ . Preferably, 0.910 to 0.925 g / cm ³ is suitably used. If it is larger than this range, transparency deteriorates,
The low-temperature sealability is also poor. On the other hand, if it is smaller than this range, the amount of sticky components increases, and the opening property after bag-making, which is the object of the present invention, deteriorates. (5) MFR: 1 to 10 g / 10 minutes. Preferably it is 2 to 5 g / 10 minutes. If it is larger than this range, the moldability with a normal T-die will be poor, and if it is smaller, the resin pressure will be high, and as a result the extrusion amount will be small, which is not preferable in production. MFR is JIS-K
7210.

Specific examples of the polyethylene resin satisfying the above conditions used in the present invention include ethylene and an α-olefin copolymer having 4 to 10 carbon atoms. As the α-olefin used, butene-1,
Hexene-1,4-methylpentene-1, octene-
One or more of 1, 1, etc. can be used. If necessary, other resins, for example, an ethylene / vinyl acetate copolymer, an ethylene / acrylate copolymer, or the like can be mixed and used as long as the properties of the film are not impaired.

As the resin used for the layer B of the present invention, any resin can be used as long as it is mainly composed of a polyethylene resin, and the same resin as that for the layer A can also be used.

The fine particles used in the layer A in the present invention are polymer fine particles having an average particle diameter of 11 to 20 μm and a decomposition start temperature of the particles of 250 ° C. or more, such as polymethyl methacrylate, polystyrene and nylon. It can be obtained by emulsion polymerization or suspension polymerization. If the average particle diameter of the fine particles is less than 11 μm, the opening property of the bag-made article is not preferable because the effect is small with respect to the added amount and only the transparency is deteriorated. If the fine particles are not spherical, it is difficult to form effective projections on the film surface, and not only does the blocking resistance decrease, but also the transparency deteriorates. The higher the decomposition initiation temperature, the better. In the extrusion and film formation of the usual T-die method,
The molten resin temperature is about 230 ° C and the decomposition onset temperature is 2
When the temperature is lower than 50 ° C., fish eyes are generated due to gelation during extrusion and film formation, and decomposition odor is generated, which is not preferable in terms of safety and health.

The addition amount of the fine particles is 0.3 to 2.0 parts by weight, but the addition amount can be reduced within this range as the average particle diameter increases. If the amount is less than 0.3 part by weight, the opening property of the bag is insufficient, and if it exceeds 2.0 parts by weight, the heat sealability and the transparency deteriorate, which is not preferable. The addition of the polymer fine particles not only improves the abrasion resistance of the sealant films but also improves the slipperiness.

In the present invention, since the layer B is a surface to be dry-laminated with the base film, the type and amount of the fine particles may be selected so as not to cause wrinkles in film winding. The fine particles to be blended are not particularly limited, but those having an average particle size of 3 to 5 μm are preferably used, and examples thereof include diatomaceous earth, silica, zeolite, and PMMA.

The unsaturated fatty acid amide used in the present invention includes erucamide, oleic amide and the like. These are easily absorbed by dry laminating adhesives, especially polyether-based polyurethane adhesives, but are necessary for imparting lubricity to the film immediately after film formation. The amount added is 0.02 to 0.07 parts by weight. If the addition amount is less than 0.02 parts by weight, wrinkles are likely to be formed at the winding part during film formation, and winding becomes difficult. If it exceeds 0.07 parts by weight, a slip agent to a laminating roll or the like during dry lamination is used. The amount of adhesion is undesirably increased. In addition, since this slip agent is a component which migrates in the film, it is preferable to add the same slip agent to the B layer in order to achieve the desired slip property.

Further, the addition of the unsaturated fatty acid bisamide in the present invention is indispensable. In particular, the slipperiness of a dry laminate film using a polyether adhesive and the opening property of a bag-made product can be remarkably improved. The amount of addition is 0.01 to 0.20 parts by weight, and it can be added to only the layer A or other layers. If the amount is less than 0.01 part by weight, the effect of the addition is not obtained. Examples of the unsaturated fatty acid bisamide used include ethylene bisoleic acid amide and ethylene bis erucic acid amide.

Since these unsaturated fatty acid bisamides have a relatively slow bleeding rate to the film surface as compared with the unsaturated fatty acid amide, the film immediately after film formation has insufficient slipperiness and is difficult to wind up. For single use, 0.2
It is necessary to add 5 parts by weight or more. In this case, a phenomenon in which the slip agent adheres and accumulates on the laminating roll is observed, so that the slip agent is not used alone. The addition to the B layer is not always necessary, unlike the unsaturated fatty acid amide described above. This is thought to be due to the slow transfer of the slip agent.

The film of the present invention has a blocking strength between layers A at 60 ° C. of 0.1 kg / 25 cm ² at 60 ° C. of a film obtained by dry laminating a corona-treated surface of layer B with a substrate and a polyether-based polyurethane adhesive. The following is the film. The blocking strength referred to in the present invention is a value measured by a blocking test method described later.

The blocking test is the most direct method for evaluating the polyethylene-based multilayer film of the present invention,
And it is effective as a quantifiable one. This evaluation is performed on the dry laminated film. The evaluation method assumes that the warehouse is in summer, and 200
The conditions for maintaining good blocking resistance and openness even after storing films of the same size for cm and storing at 40 ° C. for 6 months were examined. As a result, a test was conducted at 60 ° C. for 48 hours, and the blocking strength was 0.1 kg / 25 c.
If it is less than m ² , even after storage in a warehouse in summer after bag making, no close contact was observed in the opening property, and it was confirmed that the sealant film was extremely high in reliability and could be used with security.

In the present invention, the layer A has an average particle size of 11 μm.
By adding 0.2 to 1.0 parts by weight of inorganic or polymer fine particles having an average particle size of 4 μm or less in addition to the polymer fine particles of m or more, the blocking resistance and the slipping property can be further improved. The fine particles used are not particularly limited. For example, diatomaceous earth, zeolite and the like can be used for inorganic fine particles, and the above-mentioned polymethyl methacrylate, polystyrene, nylon and the like can be used for polymer fine particles. When the average particle size exceeds 4 μm, the transparency is reduced,
If the particles are inorganic fine particles, the abrasion resistance will be poor.

In addition, the polyethylene multilayer film of the present invention may contain commonly used antioxidants, antistatic agents, ultraviolet absorbers, coloring agents and the like. Also,
It is also possible to add a layer having various functions, for example, a gas barrier layer. Also in these cases, all layers except the layer A are considered as the layer B.

The method for forming the film of the present invention is not particularly limited, and any of known air-cooled and water-cooled inflation molding, T-die film molding and the like can be used. The molding temperature is from the viewpoint of the heat resistance of the polymer fine particles,
It is desirable not to exceed 250 ° C.

Since it is essential that the film of the present invention be laminated with a base film as a sealant film, the B layer side requires a surface treatment. As the surface treatment method, various treatment methods such as a corona discharge treatment method, an ozone treatment method, a flame treatment method, and a low-temperature plasma treatment method can be considered, but the corona discharge treatment method is generally used and is most preferable.

[0029]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Table 1 shows the types of polyethylene resins used in this example.
Table 2 shows the anti-blocking agent, and Table 3 shows the slip agent. Table 4 shows each combination.

[0030]

[Table 1] PE-1: Yumerit 2040F Ube Industries PE-2: Umerit 1540F Ube Industries PE-3: ULT SEX 1520L Mitsui Petrochemical PE-4: ULT SEX 2022L Mitsui Sekiyu PE-5: Affinity PL1845 Tow Chemical Japan PE-6: Moretech 0248CN Idemitsu Petrochemical

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

A method for processing these polyethylene resin compositions into a film will be described below. A layer is 50mm
φ and B layers are extruded using 50mmφ and 65mmφ extruders.
After melting and kneading at 30 ° C, multi-manifold type 3-layer T
The die was used as two layers. The polyethylene resin and additives used for the layer B are as follows. First, a 65 mmφ extruder corresponding to the intermediate layer was provided with an ethylene-octene-1 copolymer (manufactured by Idemitsu Petrochemical Co., Ltd., Mooretec 0248CN, MI = 2, density =
0.919 g / cm ³ ), and 0.05 parts by weight of erucamide (Diamid L-200, manufactured by Nippon Kasei) was used as a slip agent with respect to 100 parts by weight of the resin. For a 50 mmφ extruder corresponding to a casting roll layer, the same amount of polyethylene resin and the same ethylene-octene-1 copolymer and erucamide as the slipping agent were used, and the average particle size was 3.5 μm. Diatomaceous earth was used in an amount of 0.5 part by weight based on 100 parts by weight of the polyethylene resin. The kneading and film forming temperature was 230 ° C., the layer B was on the casting roll side, and the layer B side was a wetting index of 42 dyne /
cm and a thickness of 50μ
m was obtained. At this time, the thickness ratio of layer A / layer B was 1
/ 4. At this time, the “winding property” immediately after film formation was evaluated. The obtained polyethylene-based multilayer film is at 40 ° C.
For 20 hours. The “haze” was measured for the single film obtained here.

Next, the dry lamination method will be described below. Polyethylene multilayer film obtained and Co., Ltd.
Boneal 15μ, a biaxially stretched nylon film from Kojin
m was subjected to dry lamination processing with the corona-treated surfaces being bonded to each other. The adhesive used was Seikabond A-154 / C-88 manufactured by Dainichi Seika Kogyo Co., Ltd., which is a polyether-based polyurethane adhesive. The mixing ratio was 1/1, and the coating amount after drying was 2.5 g / cm ^2. And During processing, the "adhesion of the slip agent to the roll of the dry laminator" was observed. The obtained dry laminated film is 4 ° C at 40 ° C.
Aging was performed for 8 hours. For the dry laminate film obtained here, "blocking strength",
The evaluation of "coefficient of friction", "seal start temperature", and "scratch resistance" was performed. Further, the obtained dry laminated film is formed into a bag with a three-side seal bag making machine, and the same size of a bag-formed product of the same size is stacked on the bag-formed product by 200 cm.
The bag was stored at 40 ° C. for 6 months under a load of 00 g / cm ² to evaluate the “opening property”.

Next, the method of evaluating each characteristic value in the examples and comparative examples will be described in detail. (1) Blocking Resistance The blocking test method was a set of 5 cm × 8 cm dry laminated films of polyethylene-based multilayer film surfaces superimposed on each other in a size of 5 cm × 5 cm. This sample was placed on a glass plate / thin paper / one set of test pieces /
They were superposed in the order of thin paper / glass plate. Then this is 50
The sample was placed in a thermostat at a temperature of 60 ° C. or 60 ° C., and a load of 8.4 Kg was applied from above to stand for 48 hours. Thereafter, the sample taken out of the thermostat was subjected to a tensile tester under the conditions of 20 ° C. and 65% RH, and the both ends where the film was not overlapped were sandwiched between chucks, and the force for peeling off was measured. As described above, the measured value agrees very well with the evaluation of the opening property of the bag-made product. If the value at 60 ° C. is 0.1 kg / 25 cm ² or less, practically, there is no blocking. Therefore, there is no problem with the opening property.

(3) Coefficient of Friction (Slipperiness) The coefficient of friction between sealant surfaces of a dry laminate film was measured according to ASTM D-1894. The smaller the value, the better the slipperiness.

(4) Heat seal start temperature The sealant surfaces of the dry laminated films are overlapped with each other to form a seal width of 10 mm and a seal temperature of 100 ° C. to (5
(C pitch, one side heating), sealing time 1 second, sealing pressure 2.
Heat sealing was performed under the conditions of 0 Kg / cm ² , the obtained test piece was sampled in a width of 15 mm, and a T peeling test was performed at a speed of 300 mm / min using a tensile tester. The temperature at which the strength was 3.0 kg / 15 mm width or more was defined as the heat sealing start temperature. The lower the temperature, the more preferable the sealing can be at a low temperature.

(4) Haze (Haze) Measured according to JIS K 7105. The smaller the value, the better the transparency

(5) Scratch resistance The inner surfaces (the sealant film surfaces) of the dry laminate films were rubbed with a finger, and the rubbed film was observed. When the abrasion was severely whitened, it was evaluated as x, and when the degree of whitening was small, it was evaluated as ○.

(6) Adhesiveness of Slip Agent to Laminating Roll of Dry Laminator When dry laminating a base film and a polyethylene-based multilayer film, the adhesiveness of the slip agent to the roll in contact with the film immediately before lamination is checked visually. Observed. A sample with a large amount of adhesion was rated as x, a sample with some adhesion but no problem was rated as Δ, and a sample with little adhesion was rated as ○.

(7) Winding property During film production, the slipperiness immediately after film formation was confirmed by winding property (wrinkle formation, workability, etc.) in the winder section. Those that were found were evaluated as x.

(8) Opening property The obtained dry laminated film is made into a bag-making product using a three-side sealing bag-making machine, and a bag-making product of the same size is placed on top of this for 200 c.
200g / cm ² which is the same load as that of m-stacked
A weight was placed so that the opening property after opening was stored at 40 ° C. for 6 months.も の indicates that there is no trace of adhesion and the opening is good, and x indicates that the trace of adhesion is slightly observed and the opening is poor.

The evaluation results are summarized in Table 5.

Example 1 In a two-layer coextruded film of layer A / layer B, the layer A was on the heat sealing side, the layer B was on the corona layer (casting roll) side, and the layer A was the resin shown in Table 4. The composition was formulated. The resulting film has good transparency, good slipperiness and openability of the bag-made product after dry lamination, and improved scratch resistance, and also has a roll adhesive property of the slip agent during dry lamination. It was good.

Example 2 The layer A was mixed with the resin composition shown in Table 4. The opening property of the obtained film was better than that of Example 1, and there was no problem in other characteristics.

Example 3 The layer A was mixed with the resin composition shown in Table 4. The resulting film has good transparency, good slipperiness of the bag-made product after dry lamination, good openability, and improved scratch resistance, and also has good roll adhesion of the slip agent during dry lamination. It was good.

Comparative Example 1 Although the polyethylene resin used in the A layer had two endothermic peaks by DSC, one of the peaks was 100 ° C. or less, and the elution amount at 50 ° C. by TREF was 3% or more. Except for changing to a certain polyethylene resin, all were the same as in Example 2. Although the obtained dry laminated film had low-temperature sealing properties, it had high blocking strength and poor opening properties.

Comparative Example 2 The polyethylene resin used for the layer A had a Mw / Mn of 3.2 or more in the molecular weight distribution.
Example 2 except that the elution amount at 0 ° C. was 3% or more.
Same as. The obtained dry laminated film had a somewhat high blocking strength and a slightly poor opening property.

Comparative Example 3 The polyethylene resin used for the layer A was found to have an endothermic peak measured by DSC at 120 ° C. or higher and a molecular weight distribution of M
Except that w / Mn was 3.2 or more, and the elution amount at 50 ° C. by TREF was 3% or more, all were the same as in Example 2. The obtained dry laminate film had a somewhat high blocking strength, and the opening property and the adhesion were somewhat recognized. In addition, the sealing start temperature was slightly higher, and the bag making speed was slower than that of the example in order to obtain sufficient sealing strength.

Comparative Example 4 The polyethylene resin used for the A layer was changed to a resin having one endothermic peak by DSC at 100 ° C. to 110 ° C. and an elution amount at 50 ° C. by TREF of 3% or more. All were the same as Example 2. Although the obtained dry laminated film had low-temperature sealing properties, it had high blocking strength and poor opening properties.

Comparative Example 5 The endothermic peak of the polyethylene resin used for the layer A by DSC was two, but one was 120 ° C. or more,
When Mw / Mn in the molecular weight distribution is 3.2 or more, TRE
Except that the elution amount at 50 ° C. by F was changed to 3% or more, all were the same as in Example 2. The obtained dry laminate film had a somewhat high blocking strength, and the opening property and the adhesion were somewhat recognized.

Comparative Example 6 Among the antiblocking agents used in the A layer, ABA-a
Was changed to Example 2 except that the average particle size was changed to polystyrene fine particles having an average particle size of 8 μm. The obtained dry laminate film had high blocking strength and poor opening property.

Comparative Example 7 The same procedure as in Example 2 was carried out except that ABA-a was changed to diatomaceous earth having an average particle diameter of 10 μm among the antiblocking agents used in the layer A. The obtained dry laminate film had a somewhat high blocking strength and was poor in abrasion resistance.

Comparative Example 8 The anti-blocking agent used in the A layer had an average particle size of 3.5.
Except that only the μm one was used, all were the same as in Example 2. The obtained dry laminate film had high blocking strength and poor opening property.

Comparative Example 9 The procedure was the same as in Example 2 except that the amount of the unsaturated fatty acid amide added to the slip agent used in the layer A was reduced. In particular, the slipperiness immediately after film formation was poor, and wrinkles were formed by winding in the winder portion, and a good product could not be obtained. Also,
The blocking strength was high, and the opening property was poor.

Comparative Example 10 The same procedure as in Example 2 was carried out except that the amount of the unsaturated fatty acid amide added to the slip agent used in the layer A was increased. The obtained dry laminated film has blocking resistance,
Although the opening property and the slip property were good, in the dry lamination, a phenomenon was observed in which the slip agent accumulated and dropped off on the laminating roll.

Comparative Example 11 The procedure of Example 2 was repeated except that the amount of the unsaturated fatty acid bisamide added to the slip agent used in the layer A was reduced. Although the slip property immediately after film formation was good, the slip property of the dry laminated film was poor, and the blocking strength and the opening property were poor.

[0059]

[0060]

As described above, the polyethylene-based multilayer film of the present invention is a slip agent which uses a polyethylene-based resin having a small sticky component and is hardly absorbed by a dry laminating adhesive, particularly a polyether-based adhesive. By using unsaturated fatty acid bisamide in combination with unsaturated fatty acid amide and blending polymer fine particles having a large particle size, the winding property during film formation is not impaired, and the film resistance after dry lamination and after bag making is not affected. It is intended to improve the blocking property and the opening property. In addition, by using the fine particles blended in the heat seal layer together with the spherical polymer fine particles and the fine particles having a smaller average particle diameter, the contact area between the films can be efficiently reduced, and the scratch resistance can be improved. Can be. The amount of each of the unsaturated fatty acid amide and the unsaturated fatty acid bisamide was set to 0.02 to 0.07 with respect to 100 parts by weight of the polyethylene resin.
By limiting the amount to 0.02 to 0.20 parts by weight, the adhesion of the slip agent to the laminating roll during dry lamination can be improved. Furthermore, after lamination using a polyether-based dry laminating adhesive,
Even when the bag is made, the film has good slipperiness and openability, and the bag-made product does not adhere even after the bag-made product is stored for a long period of time in summer.

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Claims (2)

(57) [Claims] 1. A polyethylene-based multilayer film comprising an A layer mainly composed of a polyethylene resin and a B layer mainly composed of a polyethylene resin, wherein the A layer is as follows:
And the polyethylene-based multilayer film B
The layer of corona-treated surface was dried and laminated with a base material and a polyether-based polyurethane adhesive.
The blocking strength between the A layers at 0.1 ° C is 0.1 kg /
A polyethylene-based multilayer film having a size of 25 cm ² or less. 100 parts by weight of a copolymer of the following ethylene and an α-olefin having 4 to 10 carbon atoms. (1) The molecular weight distribution (weight average molecular weight / number average molecular weight) by gel permeation chromatography is 1.8 or more and 3.2 or less. (2) The amount of elution at 50 ° C. due to temperature rise elution fractionation is 3
%Less than. (3) After cooling completely after complete melting, in a heating thermogram measured by a differential scanning calorimeter, two or more absorption peaks are at 100 ° C. or more and less than 120 ° C. The peak is at 100 ° C. or more and less than 110 ° C., and the remaining one or more peaks are at
Less than ° C. (4) The density is 0.900 to 0.940 g / cm ³ . (5) The melt flow rate is 1 to 10 g / 10 minutes. The average particle size is 11 to 20 μm, and the particle decomposition starting temperature is 2
0.3 to 2.0 parts by weight of polymer fine particles having a temperature of 50 ° C. or higher. 0.02 to 0.07 parts by weight of unsaturated fatty acid amide. 0.01 to 0.20 parts by weight of unsaturated fatty acid bisamide. 2. The polyethylene multilayer film according to claim 1, wherein the layer A further contains 0.2 to 1.0 parts by weight of inorganic or polymer fine particles having an average particle size of 4.0 μm or less.