JP2016049727A - Sealant film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealant film exhibiting good slipperiness even just after unwinding and keeping slipperiness good even after lamination.SOLUTION: There is provided a polyethylene sealant film containing 3 layers of at least a seal layer (A layer), an intermediate layer (B layer) and a laminate layer (C layer), where a resin constituting the A layer contains a polyethylene resin of 50 to 95 pts.wt. and a polypropylene resin of 50 to 5 pts.wt. and the A layer contains at least organic lubricant, and has a haze value of 15 or less and static coefficient of friction of seal layers each other measured within 30 minutes after unwinding from a roll state of 0.20 or less.SELECTED DRAWING: None

Description

  The present invention relates to a polyethylene sealant film. More specifically, the present invention relates to a linear low-density polyethylene film that is excellent in blocking resistance and heat sealability, and that exhibits good slipping properties even after unwinding from a roll.

  In recent years, packaging or containers using films have been used in a wide range of fields due to convenience, resource saving, environmental load reduction, and the like. Films are advantageous in that they are lightweight, easy to dispose of, and low in cost compared to conventional molded containers and molded products.

  The sealant material is generally laminated with a base material such as a biaxially stretched nylon film, a biaxially stretched ester film, or a biaxially stretched polypropylene film, which is inferior in low-temperature thermal adhesion to the sealant material. There was a problem of blocking during laminating and bag making. In the old days, there has been known a method for avoiding blocking between sealant materials or between a sealant material and a base material by shaking powder such as starch for the purpose of improving it. However, this not only contaminates the periphery of the film processing apparatus, but also causes problems such as hygiene such that the appearance of the packaged food is significantly deteriorated, or the powder adhering to the sealant material is directly mixed with the food in the package. It was.

  In order to solve the above-mentioned problem, a laminated polyethylene-based unstretched film is disclosed that has good heat-sealability and anti-blocking property while having a good sliding property in a heat-sealable polyethylene-based resin film. (For example, refer to patent document 1 etc.) However, immediately after unwinding from the roll state, such a technique has a problem that the workability deteriorates due to blocking.

  Further, the laminated sealant has a problem that the slipperiness on the sealant side is deteriorated.

Japanese Patent No. 4779822

  The present invention has been made against the background of such prior art problems. That is, an object of the present invention is to produce a sealant film that exhibits better slippery even immediately after unwinding and keeps the slippery good even after lamination, as compared with the prior art.

As a result of intensive studies to achieve the above object, the present inventors have completed the present invention. That is, the present invention
[1] At least three layers including a seal layer (A layer), an intermediate layer (B layer), and a laminate layer (C layer), and the resin constituting the A layer is 50 to 95 parts by weight of a polyethylene resin, and a polypropylene resin 50 It is a sealant film containing an organic lubricant in at least layer A at ˜5 parts by weight, the haze value is 15 or less, and the static friction coefficient between the seal layers measured within 30 minutes after unwinding from the roll state. A polyethylene-based sealant film, which is 0.20 or less.
[2] Measurement of polyethylene-based sealant film [3] simple substance according to [1], wherein the resin constituting the seal layer (A layer) is 70-95 parts by weight of polyethylene-based resin and 30-5 parts by weight of polypropylene-based resin 3. The polyethylene sealant film according to claim 1, wherein at least one surface has a three-dimensional arithmetic average roughness SRa of 0.01 μm or more and less than 0.25.
[4] The polyethylene resin contained in the seal layer (A layer) is a linear low density polyethylene, and 90 parts by weight or more of the intermediate layer (B layer) and the laminate layer (C layer) are linear low density. The polyethylene sealant film according to any one of [1] to [3], which is made of a polyethylene resin.
[5] Melt flow rate (MFR) measured in ASTM D-1238 (230 ° C., 21.18 N) of the polypropylene resin contained in the seal layer (A layer) is 0.6 to 3.0 g / 10 min. The polyethylene sealant film according to any one of [1] to [4], wherein the polyethylene resin has a melt flow rate at 230 ° C. of 2.5 to 4.5 g / 10 minutes.
[6] The density of the seal layer (A layer) is 900 to 935 g / cm 3, the density of the base material layer (B layer) is 900 to 935 g / cm 3, and the density of the laminate layer (C layer) is 920 to 945 g / cm 3, The polyethylene-based sealant film according to any one of [1] to [5], wherein the average density of the polyethylene-based resin in each of the layers is sealant layer (A layer) ≦ base layer (B layer) <laminate layer (C layer) .
[7] The polyethylene sealant film according to any one of [1] to [6], wherein the anti-blocking strength measured according to ASTM D1893-67 is 60 mN / 20 mm or less.
[8] The polyethylene sealant film according to any one of [1] to [7], wherein a minimum temperature at which the heat seal strength is 4.9 N / 15 mm or more is 95 ° C. or more and less than 125 ° C.

  Even when the sealant film of the present invention is wound up as a single body, it does not roll-block, and exhibits good slippery properties even immediately after unwinding. Further, even after laminating, there is little deterioration in slipperiness, good openability at the time of filling, and less processing loss.

  Hereinafter, the present invention will be described in detail.

  The polyethylene-based sealant film of the present invention includes at least a seal layer (A layer), an intermediate layer (B layer), and a laminate layer (C layer) in this order. The outermost layers are the A layer and the C layer, respectively, and may include a recovery layer and other layers, and the intermediate layer may be composed of a recovered raw material, or may include a recovered raw material.

  Examples of the polyethylene resin to be used include those obtained by mixing one or more selected from ethylene / α-olefin copolymers and high-pressure polyethylene. The ethylene / α-olefin copolymer is a copolymer of ethylene and an α-olefin having 4 to 18 carbon atoms, and examples of the α-olefin include butene-1, hexene-1, 4-methylpentene-1, Examples include octene-1 and decene-1. Films obtained from these polyethylene-based resins have excellent heat seal strength, hot tack properties, contaminant sealing properties, and impact resistance. A resin such as an ethylene / vinyl acetate copolymer, an ethylene / acrylic acid ester copolymer, or the like may be mixed and used. Among them, the polyethylene resin used in the present invention has a melt flow rate (hereinafter sometimes referred to as MFR) of 2.5 to 4 in terms of film forming properties, physical properties and functional properties of the film-formed product. About 5 g / min is preferable. Here, MFR was measured based on ASTM D1893-67. The polyethylene resin is synthesized by a method known per se.

  In the linear low-density polyethylene composite film of the present invention, an appropriate amount of a heat stabilizer, an antioxidant, an antistatic agent, an antifogging agent, and an optional layer as long as the purpose of the present invention is not impaired. Neutralizing agents, lubricants, nucleating agents, colorants, other additives, inorganic fillers, and the like can be blended.

  It is preferable to add an antioxidant to the polyethylene resin, and a phenolic or phosphite-based combination, or those having a phenolic and phosphite-based skeleton in one molecule may be used alone.

  The lower limit of the film thickness is preferably 10 μm, more preferably 30 μm, and even more preferably 35 μm. If it is less than the above, the waist may be too weak and difficult to process. The upper limit of the film thickness is preferably 100 μm, more preferably 50 μm, and still more preferably 40 μm. If the above is exceeded, the waist may be too strong and difficult to process.

  The lower limit of the seal layer ratio is preferably 10%%, more preferably 15%, and still more preferably 18%. If it is less than the above, the sealing strength may be insufficient. The upper limit of the seal layer ratio is preferably 40%, more preferably 30%, and further preferably 25%. When the above is exceeded, there are too many additives, which may increase the cost.

The lower limit of the laminate layer ratio is preferably 5%, more preferably 16%. If it is less than the above, the anti-blocking agent added to the seal layer or intermediate layer pushes up the laminate layer, and bubbles may be generated at the bonding interface with the base film.
The upper limit of the laminate layer ratio is preferably 50%, more preferably 32%. If the above is exceeded, the film may be too stiff and difficult to process.

  In the present invention, the density range of the raw polyethylene resin used for blending is more preferably 905 to 965 kg / m3, and further preferably 910 to 960 kg / m3. A polyethylene resin having a density of less than 900 kg / m3 has poor handling properties. In addition, a polyethylene resin having a density greater than 970 kg / m 3 is difficult to obtain because it is difficult to polymerize, which is inconvenient.

  The polyethylene resin constituting the present invention may be a single system, but it is preferable to blend two or more polyethylene resins having different densities in the above density range. By this measure, the fish eye caused by the high molecular weight component of the polyethylene resin can be reduced. The reason is that in the case of polyethylene resins having the same density, the higher the density of the resin, the higher the number of high molecular weight substances. Therefore, the fisheye tends to increase as the density of the resin increases. Therefore, when two or more types of polyethylene resin with relatively low density and low fisheye and polyethylene resin with high density and fisheye are mixed, compared with a single polyethylene resin with the same density as the mixture, there is less fisheye. It is guessed that it became. Two kinds of the blends exhibit a sufficient effect.

  The polyethylene resin used for the blending preferably has a molecular weight distribution (Mw / Mn) of 2.0 to 3.5. 2.2-3.3 are more preferable, and 2.4-3.1 are more preferable. When a polyethylene-based resin having a molecular weight distribution (Mw / Mn) of less than 2.0 is used, stable production in film production becomes difficult due to the occurrence of neck-in due to the flow characteristics of the resin when melted. It leads to deterioration. In addition, it is inconvenient to use a polyethylene resin having a molecular weight distribution larger than 3.5, because the production of fisheye caused by a high molecular weight substance increases.

  In this case, the average density of the polyethylene resin in each layer of the film is preferably sealant layer (A layer) ≦ base layer (B layer) <laminate layer (C layer). Since the blended organic lubricant does not easily move to a dense layer, it is effective for maintaining the slipperiness after lamination.

  In the present invention, the sliding property immediately after unwinding is remarkably improved by adding a polypropylene resin to the seal layer (A layer).

  The reason for this will be explained. Polypropylene resin is a component that is incompatible with polyethylene resin, but can be finely dispersed by selecting a polypropylene resin having a specific melt flow rate and adding a specific amount.

  A film that has been improved in the slipperiness of the film by adding an organic lubricant or the like disclosed in Patent Document 1 has a small amount of bleed-out to the film surface while being stored in a roll state, and further, the film is removed from the roll. Even when unwinding, since the organic lubricant in the surface layer enters the inside, the amount of the organic lubricant present on the film surface is substantially small.

  One of the causes is that the front and back of the film are in close contact with each other in a roll state (a phenomenon called blocking).

  In the finely dispersed state, fine irregularities of about several μm can be expressed on the surface of the seal layer. Thereby, blocking resistance becomes favorable. However, it is surprisingly possible to obtain a highly transparent sealant film. Further, when the sealant film is rolled up, the seal layer (polyethylene resin containing polypropylene resin) and the laminate layer (only polyethylene resin) come into contact with each other, but there are incompatible components with each other. Therefore, it is assumed that blocking is unlikely to occur, and therefore the organic lubricant in the seal layer tends to stay on the surface of the seal layer.

The lower limit of the density of the polypropylene resin added to the seal layer is preferably 870 kg / cm ³ , and more preferably 885 kg / cm ³ . If it is less than the above, polypropylene may not be compatible at all, and the film may be whitened. The upper limit of the density of the polypropylene resin added to the seal layer is preferably 920 kg / cm ³ , more preferably 900 kg / cm ³ . If the above is exceeded, polypropylene may be completely compatible, and the surface layer of the seal layer may not be uneven.

The lower limit of the melt flow rate (MFR) of the polypropylene resin added to the sealing layer is preferably 0.6 g / 10 minutes, more preferably 1.0 g / 10 minutes, and further preferably 1.2 g / 10 minutes. It is. If it is less than the above, the compatibility of polypropylene is poor, and the film may be whitened.
The upper limit of the melt flow rate of the polypropylene resin added to the seal layer is preferably 3.0 g / 10 minutes, more preferably 2.0 g / 10 minutes, and even more preferably 1.7 g / 10 minutes. If the above is exceeded, polypropylene may be completely compatible, and the surface layer of the seal layer may not be uneven.

  The polypropylene resin added to the seal layer is not particularly limited as long as the above is satisfied, but is preferably a polypropylene random copolymer, and a large amount (about 85% by weight or more) of propylene and a small amount (about 15% by weight or less). ) Of α-olefin and a random copolymer (polypropylene-α-olefin random copolymer). As the α-olefin monomer for obtaining such a polypropylene random copolymer, ethylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, and the like can be used. It is particularly preferable to use ethylene and butene-1 from the viewpoint of properties. Moreover, the alpha-olefin used for copolymerization should just be at least 1 or more types, and can mix and use 2 or more types as needed.

  The lower limit of the amount of polypropylene resin added to the seal layer is preferably 5%, more preferably 8%, and even more preferably 10%. If it is less than the above, blocking may be caused, and the slipperiness immediately after unwinding may deteriorate. The upper limit of the amount of polypropylene resin added to the seal layer is preferably 50%, more preferably 30%, and even more preferably 15%. However, when the above is exceeded, the low-temperature sealability may deteriorate.

  Patent No. 4411960 discloses a sealant film in which 2.0% of high-density polyethylene resin is added to polypropylene resin to develop good irregularities. However, when the polyethylene resin is the base, polypropylene resin is used as the base. The addition of 2% alone does not provide a favorable effect, and as a result of trial and error, it has been found that irregularities that improve blocking can be formed only by adding about 5% polyethylene.

  Furthermore, when polypropylene is added to the polyethylene resin, the low-temperature sealability deteriorates, but the present invention succeeded in improving the slipperiness without impairing the low-temperature sealability.

In the present invention, it is preferable to add an organic lubricant to at least the sealing layer (A).
The slipperiness and blocking prevention effect of the laminated film is improved, and the handleability of the film is improved. The reason for this is that the organic lubricant bleeds out and is present on the film surface, so that the lubricant effect and the release effect are expressed. Furthermore, it is preferable to add an organic lubricant having a melting point not lower than room temperature. Organic lubricants include fatty acid amides and fatty acid esters. Specific examples include oleic acid amide, erucic acid amide, behenic acid amide, ethylene bis oleic acid amide, hexamethylene bis oleic acid amide, and ethylene bis oleic acid amide. These may be used alone, but it is preferable to use two or more of them in combination since the slipperiness and the anti-blocking effect can be maintained even in a harsh environment.

The lower limit of the organic lubricant amide concentration in the seal layer is preferably 600 ppm, more preferably 800 ppm. If it is less than the above, the slipperiness may be deteriorated.
The upper limit of the organic lubricant amide concentration in the seal layer is preferably 2000 ppm, more preferably 1500 ppm. Exceeding the above may cause slippage and cause winding deviation.
For example, if erucic acid amide is less than 100 ppm, the slipperiness is insufficient, and if it exceeds 1500 ppm, the slipperiness is satisfactory, but the antiblocking effect at high temperatures is not satisfactory. In that case, the combined use of ethylenebisoleic acid amide having a relatively high melting point can improve the anti-blocking effect at high temperatures, and can achieve both slipperiness and anti-blocking effect.

  In the present invention, it is necessary to add inorganic particles as an antiblocking agent to at least the seal layer (A layer). By this measure, it is possible to maintain a low temperature sealing property and to provide a high anti-blocking effect. As the reason, since the projection is formed on the film surface by blending the inorganic particles, the contact area of the film is reduced, and as a result, it is presumed that the anti-blocking effect is obtained. Furthermore, when the inorganic particles having different particle diameters and shapes are blended, complex protrusions are formed even in the recesses on the film surface, and a higher blocking prevention effect can be obtained. A film having protrusions of different heights on the film surface is superior in blocking resistance than a film having protrusions of the same height on the film surface. In addition, you may mix | blend said inorganic particle with a laminate layer (C layer) or an intermediate | middle layer (B layer) as needed.

  The composition of the inorganic particles is not limited, but silica, zeolite, diatomaceous earth, talc and the like can be used. It is preferable to use a mixture of silica and zeolite. Further, those having a non-porous surface and a narrow particle size distribution are preferred. The reason is that when the surface is porous, the film may foam and the appearance may deteriorate due to the influence of moisture adsorbed on the inorganic particles. In addition, when the particle size distribution is wide, inorganic particles may be deposited on the lip portion of the T die in the production of the film, which may hinder productivity.

  The lower limit of the particle size of the antiblocking agent is preferably 3 μm. If it is less than the above, the effect on blocking may be insufficient. The upper limit of the particle size of the antiblocking agent is preferably 20 μm, more preferably 16 μm. If the above is exceeded, the transparency of the film may deteriorate.

  The lower limit of the concentration of the antiblocking agent in the seal layer is preferably 0.1%, more preferably 0.5%, and even more preferably 0.8%. If it is less than the above, the slipperiness may be deteriorated. The upper limit of the concentration of the antiblocking agent in the seal layer is preferably 5%, more preferably 3%, and even more preferably 2%. Exceeding the above may cause slippage and cause winding deviation.

The lower limit of the density of the intermediate layer is preferably 920 kg / m ³ , more preferably 925 kg / m ³ , and further preferably 930 kg / m ³ . If it is less than the above, the waist may be weak and difficult to process. The upper limit of the density of the intermediate layer is preferably 960 kg / m ³ , more preferably 940 kg / m ³ , and still more preferably 935 kg / m ³ .

  An organic lubricant described in the section of the seal layer may be used for the intermediate layer, and the lower limit of the organic lubricant is preferably 600 ppm, more preferably 800 ppm. If it is less than the above, the slipperiness may be deteriorated. The upper limit of the erucic acid amide concentration in the intermediate layer is preferably 2000 ppm, more preferably 1500 ppm. Exceeding the above may cause slippage and cause winding deviation.

  Furthermore, in this case, it is preferable that 10 to 30% by mass of the recovered resin is blended in the intermediate layer (C) of the film.

  The lower limit of the blocking strength is preferably 5 mN / 20 mm, more preferably 10 mN / 20 mm, and further preferably 15 mN / 20 mm. The upper limit of the blocking strength is preferably 60 mN / 20 mm, more preferably 50 mN / 20 mm, and still more preferably 40 mN / 20 mm. When the above is exceeded, the slipperiness immediately after unwinding may deteriorate.

  The lower limit of haze is preferably 3%, more preferably 5%, and even more preferably 8%. If it is less than the above, there is a possibility that the anti-blocking agent is small, which may cause blocking. The upper limit of haze is preferably 15%, more preferably 12%, and even more preferably 10%. When the above is exceeded, it may be difficult to visually recognize the contents.

  The lower limit of the heat seal starting temperature is preferably 95 ° C./4.9 N, and more preferably 105 ° C./4.9 N. If it is less than the above, it may be fused by heat other than the seal. The upper limit of the heat seal starting temperature is preferably 125 ° C./4.9 N, and more preferably 120 ° C./4.9 N. If the above is exceeded, the heat required for sealing may increase and the cost may increase.

  The lower limit of the seal strength is preferably 5 N / 15 mm, more preferably 6 N / 15 mm. If it is less than the above, it may be easy to break the bag after bag making. The upper limit of the seal strength is preferably 12 N / 15 mm, more preferably 10 N / 15 mm. If the above is exceeded, it may be difficult to open the bag after bag making.

  The lower limit of the single unit static friction coefficient is preferably 0.05, more preferably 0.08, and even more preferably. If it is less than the above, the film may slip too much during winding and cause winding deviation. The upper limit of the static friction coefficient of a single substance becomes like this. Preferably it is 0.20, More preferably, it is 0.15, More preferably, it is 0.10. The slipperiness of the film is poor, and loss during processing may increase.

  The lower limit of the static friction coefficient measured within 30 minutes after unwinding is preferably 0.05, more preferably 0.08. If it is less than the above, the film may slip too much during winding and cause winding deviation. The upper limit of the static friction coefficient measured within 30 minutes after unwinding is preferably 0.25, more preferably 0.18, and even more preferably 0.10. The slipperiness of the film is poor, and if it exceeds the above, loss during processing may increase.

  The lower limit of the static friction coefficient after lamination is preferably 0.05, more preferably 0.08. If it is less than the above, the film may slip too much during winding and cause winding deviation. The upper limit of the static friction coefficient after lamination is preferably 0.20, and more preferably 0.15. When the above is exceeded, the openability after bag making is poor, and loss during processing may increase.

  The lower limit of Young's modulus (MD) is preferably 100 MPa, more preferably 200 MPa. If it is less than the above, the waist may be too weak to be processed. The upper limit of Young's modulus (MD) is preferably 800 MPa, more preferably 600 MPa.

  The lower limit of Young's modulus (TD) is preferably 100 MPa, more preferably 200 MPa. If it is less than the above, the waist may be too weak to be processed. The upper limit of Young's modulus (TD) is preferably 1000 MPa, more preferably 600 MPa.

The lower limit of the three-dimensional arithmetic average roughness SRa is preferably 0.05 μm, more preferably 0.08 μm, and still more preferably 0.10 μm. If it is less than the above, it may be easy to block after roll or bag making. The upper limit of the three-dimensional arithmetic average roughness SRa is preferably 0.25 μm, more preferably 0.2 μm. If the above is exceeded, the effect of increasing the surface roughness against blocking may be reduced.

  The method for forming the polyethylene-based sealant film of the present invention is not particularly limited. For example, an inflation method or a T-die method can be used, but a T-die method is preferable in order to increase transparency. In the inflation method, the cooling medium is air, whereas in the T-die method, a cooling roll is used, which is an advantageous manufacturing method for increasing the cooling rate.

In the present invention, it is preferable to perform active ray treatment such as corona treatment on the laminate layer (C layer) surface of the polyethylene-based resin laminated film described above. The correspondence improves the laminate strength. The lower limit of the laminate layer (C layer) wetting tension is preferably 30N, and more preferably 40N. If it is less than the above, the laminate strength may decrease.
The upper limit of the wetting tension is preferably 55N, more preferably 50N. Exceeding the above may increase the amount of organic lubricant transferred to the surface of the laminate layer (A), leading to a decrease in laminate adhesive strength.

  The melt-formed film is preferably wound up as a roll. The winding length is not particularly limited, but the upper limit is preferably 8000 m. Exceeding the above may increase the weight and make handling difficult. The lower limit is preferably 100 m. If it is less than the above, the processing efficiency may decrease and the cost may increase.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, it is not limited to these. The characteristics obtained in each example were measured and evaluated by the following methods.

(1) Resin density The density was evaluated according to JIS K7112: 1999.

(2) Blocking strength According to ASTM D1893-67, the laminate layer and the seal layer of the film were overlapped and measured.

(3) Heat seal start temperature Heat seal strength: Heat seal conditions and strength measurement conditions are as follows. That is, the heat seal surfaces of the films are overlapped, and a sealant film sandwiched between 12 μm biaxially stretched PET films for preventing fusion is 90 ° C, 95 ° C, 100 ° C, 105 ° C, 110 ° C, 115 ° C, Heat sealing was performed at 120 ° C., 125 ° C., and 130 ° C. at a pressure of 0.1 MPa for 1 second with a seal bar width of 10 mm, and then allowed to cool. Subsequently, the PET film was removed, and test pieces each having a width of 15 mm were cut from the heat-sealed film at each temperature, and the peel strength when the heat seal part was peeled off at a crosshead speed of 200 mm / min was measured for each test piece. .

(4) Three-dimensional surface roughness Arithmetic average roughness SRa
The three-dimensional surface roughness SRa uses contact type surface roughness (manufactured by Kosaka Laboratories, Model ET4000A), and arbitrarily measures the surface roughness of a measuring surface of 1 mm × 0.2 mm from a 3 cm × 3 cm square film piece. The arithmetic average roughness SRa was determined.

(5) Coefficient of static friction The seal layer sides of the film were overlapped and measured according to JIS K7125. The normal measurement was carried out in a state where the organic lubricant was bleed out on the film surface after 30 minutes or more had elapsed after collecting the sample. When measuring the static friction coefficient within 30 minutes after unwinding, a sample was taken at a portion where a surface layer of 5 m or more of a roll-shaped film was drawn. When the outermost film is used, the adhesion between the films during storage is weak, and measurement may not be performed correctly. The elapsed time after unwinding is preferably within 30 minutes, more preferably within 15 minutes. If the above is exceeded, the organic lubricant will bleed out on the surface of the film and the measurement will not be suitable.

(6) Melt flow rate Based on ASTM D-1238, the measurement was performed at 230 ° C and a load of 21.18N.

(Example 1)
[Creating a sealant film]
(Polyethylene composition of seal layer (A layer))
Resin Density 915 kg / ^{m 3} of a polyethylene resin (manufactured by Dow Chemical Company ELITE 5220G) 90% to the resin density 890kg / m3, MFR1.4g / 10 min Polypropylene resin (manufactured by Sumitomo Chemical Co., Noblen S131) 10% mixture did. Further, 1.17% of amorphous silica having a particle size of 10 μm and 0.49% of zeolite having a particle size of 4 μm were added as an antiblocking agent, and 1000 ppm of erucic acid amide was added as an organic lubricant. Each additive was mixed as a masterbatch of polyethylene resin.

(Polyethylene composition of intermediate layer (B layer))
A 68% composition of polyethylene resin (Sumitomo Chemical Co., Sumikasen FV407) with a resin density of 930 kg / m ³ , 12% of resin density 962 kg / m ^{3 of} Prime Polymer Co., Ltd. (MORETECH 0408G), and 20% of the recovered raw material were mixed. 1000 ppm of erucic acid amide was added as an organic lubricant. The additive was mixed as a polyethylene resin masterbatch.

(Laminated layer (C layer) polyethylene composition)
80% of a polyethylene resin having a resin density of 930 kg / m ³ (FV407, manufactured by Sumitomo Chemical Co., Ltd.) and 20% of a polyethylene resin having a resin density of 962 kg / m ³ and a molecular weight distribution of 2.8 (manufactured by Prime Polymer, 0408G) were mixed.

Use a polyethylene resin composition for layer B with a three-stage single screw extruder with a screw diameter of 90 mm, and a polyethylene resin composition for layer A and layer C with a three-stage single screw extruder with 45 mm and 60 mm, respectively. A three-layer type T-slot die designed with a width of 800mm, two pre-lands, and a stepped portion with a curved shape so that the flow of molten resin is uniform and the flow in the die is uniform. Were introduced in the order of A layer / B layer / C layer, and the die outlet temperature was extruded at 220 ° C. The lip gap was 1.6 mm.
The molten resin sheet coming out of the die was cooled with a cooling roll at 40 ° C. to obtain a polyethylene-based laminated film having a layer thickness of 8/22/7 (μm) in the configuration of A layer / B layer / C layer. The silo and hopper for feeding to the extruder were also replaced with nitrogen gas. When cooling with the cooling roll, both ends of the film on the cooling roll are fixed with an air nozzle, and the entire width of the molten resin sheet is pressed against the cooling roll with an air knife, and at the same time, a vacuum chamber is acted between the molten resin sheet and the cooling roll. Air entrainment was prevented. The air nozzles were installed in series in the film traveling direction at both ends. The wind direction of the air knife was 45 degrees with respect to the traveling direction of the extruded sheet. Further, the direction of the suction port of the vacuum chamber was adjusted to the traveling direction of the extruded sheet. Furthermore, the die was surrounded by a sheet so that the molten resin sheet was not exposed to wind. The surface layer of the C layer was subjected to corona treatment. The film forming speed was 20 m / min. The film formed was trimmed at the ear and rolled up.

[Creation of dry laminate film]
The film according to the present invention and a base film (biaxially stretched polyester film manufactured by Toyobo, E5100, thickness 12 μm), 32.4 parts by mass of an adhesive for ester dry lamination (DIC Graphics, LX500), a curing agent As an ester adhesive obtained by mixing 2.2 parts by mass (manufactured by DIC Graphics, KR90S) and 65.4 parts by mass of ethyl acetate, and the application amount of the adhesive is 3.0 g / m 2 It was dry laminated so that The laminated laminate film was kept at 40 ° C. and aged for 3 days to obtain a dry laminate film.

(Example 2)
In Example 1, a sealant film was obtained in the same manner except that the mixing ratio of the seal layer (A layer) resin was 15% for polypropylene resin and 85% for polyethylene resin.

(Example 3)
A sealant film was obtained in the same manner as in Example 1, except that the mixing ratio of the seal layer (A layer) resin was 30% for polypropylene resin and 70% for polyethylene resin.

Example 4
A sealant film was obtained in the same manner as in Example 1 except that the concentration of erucamide added to the seal layer (A layer) was 800 ppm.

(Example 5)
A sealant film was obtained in the same manner as in Example 1, except that the thickness of (A layer) / (B layer) / (C layer) was 6.5 / 16.2 / 5.8 μm (total 30 μm). .

(Example 6)
A sealant film was obtained in the same manner as in Example 1 except that the silica concentration added to the seal layer (A layer) was 0.58%.

(Example 7)
A sealant film was obtained in the same manner as in Example 1 except that the concentration of zeolite added to the seal layer (A layer) was 0.25%.

(Comparative Example 1)
A sealant film was obtained in the same manner as in Example 1 except that the polypropylene resin was not added and the polyethylene resin was 100%. However, the unevenness of the film became small, and the slipperiness immediately after unwinding was not obtained.

(Comparative Example 2)
In Example 1, a sealant film was obtained in the same manner except that the mixing ratio of the sealing layer resin was changed to 55% polypropylene resin and 45% polyethylene resin. However, it resulted in the deterioration of transparency.

(Comparative Example 3)
In Example 1, the same method was used except that the polypropylene resin used was manufactured by Sumitomo Chemical Co., Ltd., Noblene S131 was melted and re-pelleted, and the MFR was intentionally increased to 3.2 g / 10 min. A sealant film was obtained. However, the polypropylene resin was completely compatible with the polyethylene resin, and the unevenness of the film was reduced, and the slipperiness immediately after unwinding was not obtained.

(Comparative Example 4)
In Example 1, an attempt was made to obtain a sealant film in the same manner except that the polypropylene resin used was changed to a polypropylene resin having a resin density of 900 kg / m3 and an MFR of 0.5 g / 10 min (manufactured by Sumitomo Chemical Co., Ltd., Nobrene D101). . However, the polypropylene resin was completely incompatible with the polyethylene resin and a film could not be obtained.

(Comparative Example 5)
In Example 1, a sealant film was obtained in the same manner except that the concentration of erucamide added to the seal layer (A layer) was 500 ppm. However, the slipperiness deteriorated.

  The results are shown in Table 1.

  Compared with the prior art, it was possible to produce a sealant film that showed good slippery even immediately after unwinding and that remained slippery after lamination. Loss during processing can be reduced, which can greatly contribute to the industry.

Claims (8)

  At least three layers including a seal layer (A layer), an intermediate layer (B layer), and a laminate layer (C layer), and the resin constituting the A layer is 50 to 95 parts by weight of a polyethylene resin, and 50 to 5 weights of a polypropylene resin. Part, the sealant film containing an organic lubricant in at least layer A, having a haze value of 15 or less, and a coefficient of static friction between the seal layers measured within 30 minutes after unwinding from the roll state is 0.20. A polyethylene-based sealant film characterized by:   The polyethylene sealant film according to claim 1, wherein the resin constituting the seal layer (A layer) is 70 to 95 parts by weight of a polyethylene resin and 30 to 5 parts by weight of a polypropylene resin.   3. The polyethylene sealant film according to claim 1, wherein, in a single measurement, at least one surface has a three-dimensional arithmetic average roughness SRa of 0.01 μm or more and less than 0.25.   The polyethylene resin contained in the seal layer (A layer) is a linear low density polyethylene, and 90 parts by weight or more of the intermediate layer (B layer) and the laminate layer (C layer) is a linear low density polyethylene resin. The polyethylene-based sealant film according to any one of claims 1 to 3, wherein   The melt flow rate (MFR) measured in ASTM D-1238 (230 ° C., 21.18 N) of the polypropylene resin contained in the seal layer (A layer) is 0.6 to 3.0 g / 10 minutes, The polyethylene-based sealant film according to any one of claims 1 to 4, wherein a melt flow rate of the polyethylene-based resin at 230 ° C is 2.5 to 4.5 g / 10 minutes. The density of the sealing layer (A layer) is 900 to 935 g / cm ³ , the density of the base material layer (B layer) is 900 to 935 g / cm ³ , and the density of the laminate layer (C layer) is 920 to 945 g / cm ³ , The polyethylene-based sealant film according to any one of claims 1 to 5, wherein the average density of the polyethylene-based resin in each of the layers is sealant layer (A layer) ≤ base material layer (B layer) <laminate layer (C layer).   The polyethylene-based sealant film according to any one of claims 1 to 6, wherein the anti-blocking strength measured in accordance with ASTM D1893-67 is 60 mN / 20 mm or less.   The polyethylene sealant film according to any one of claims 1 to 7, wherein the lowest temperature at which the heat seal strength is 4.9 N / 15 mm or more is 95 ° C or higher and lower than 125 ° C.