JP2006021472A - Polypropylene anti-fogging film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide a polypropylene anti-fogging film with advantages such as successful printability by an aqueous ink despite the retention of excellent proper anti-fogging properties/transparency of the film, non-generation of print migration, ink shift and smudge due to friction with or adhesion to a contact object such as any other film or paper, non-occurrence of obnoxious smell due to a residual organic solvent or its adsorption into a packed content, ability to keep beautiful/clean environments during circulation or goods display and suitability for lamination between a printing layer by the aqueous ink and the film. <P>SOLUTION: This film is constituted of a laminate with not less than two layers such as a base material layer composed mainly of a polypropylene resin and a heat fusion layer composed mainly of a polyolefin resin formed at least on one surface of the base material layer. In addition, the layers constituting the laminate include a layer having anti-fogging properties and an aqueous ink adhesive surface layer with not less than 100 g/15 mm lamination strength with the aqueous ink printing layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polypropylene antifogging film excellent in printability, and more particularly to a polypropylene antifogging film excellent in printability and transparency with water-based ink and having a laminating property with a printing layer using water-based ink.

  Polypropylene antifogging films are widely used as packaging materials for various foods including fresh products because they are extremely excellent in antifogging properties, transparency and price. Also, these polypropylene antifogging films are usually printed.

Due to environmental problems in recent years, printing on general films is proceeding with water-based ink from conventional printing using organic solvent-based inks to printing using water-based inks. Also for printing on polypropylene films, a method for improving ink adhesion by improving water-based ink has been proposed by an ink manufacturer as a measure for improving printability with water-based ink (see, for example, Patent Document 1 and Patent Document 2). ).
Japanese Patent Laid-Open No. 10-1636 JP 11-279471 A

  However, printing with a water-based ink on a polypropylene antifogging film has high transferability of ink to other surfaces and low practicality compared with printing with a conventional organic solvent-based ink. Even with printing using an improved water-based ink for the purpose of improving ink adhesion, the ink adhesion is not sufficient. As described above, it is difficult to significantly improve the ink adhesion only by modifying the ink. In addition, the price of the ink is increased, which is not practical. For this reason, it has been difficult to switch from organic solvent-based ink to water-based ink.

  In view of the problems of the conventional polypropylene antifogging film, the present invention has good printability with water-based ink while maintaining the excellent antifogging property and transparency inherent in the polypropylene antifogging film. In addition, there is no printing transfer, ink misalignment or smudge due to friction or contact with other film, paper, or other contact objects, and there is no off-flavor caused by residual organic solvent or adsorption to the package contents. It is an object of the present invention to provide a low cost polypropylene antifogging film that maintains a beautiful and clean environment at the time of display and has a laminate suitability with a printing layer using water-based ink.

  In order to achieve the above object, the polypropylene antifogging film of the present invention comprises a base layer mainly composed of a polypropylene resin and a heat mainly composed of a polyolefin resin formed on at least one surface of the base layer. A water-based ink comprising a laminate of two or more layers having a fusion layer, and having a laminate strength of a layer having antifogging properties and a water-based ink printing layer of 100 g / 15 mm or more in the layers constituting the laminate. It has the adhesive surface layer, It is characterized by the above-mentioned.

  Here, the laminate strength is a value at the time of peeling between the water-based ink printed layer and the water-based ink adhesion surface layer of the polypropylene antifogging film.

  Also, having anti-fogging properties means that the dew adherence state is completely observed when the dew adherence state of the film after 2 days has been evaluated by repeating the temperature change every 5 hours in a warm water sealed atmosphere between 5 and 30 ° C. This means that dew does not adhere.

  Moreover, the water-based ink adhesion surface layer can be obtained by surface-activating the film surface in a nitrogen concentration atmosphere higher than the nitrogen concentration in the air.

  Further, the heat shrinkage rate of the polypropylene antifogging film at 120 ° C. for 5 minutes can be 10% or less.

  Moreover, at least the base material layer of the polypropylene antifogging film can be a layer containing an antifogging agent.

  Moreover, the thickness of a heat-fusion layer can be 0.5-10 micrometers.

  In addition, a polypropylene anti-fogging film can be used for fresh product packaging.

  According to the polypropylene antifogging film of the present invention, the printability by water-based ink is good and other films, papers, etc. without impairing the excellent antifogging property and transparency inherent in the polypropylene antifogging film. It is possible to eliminate printing transfer, ink misalignment, and contamination due to friction and contact with the contact material, and maintain a beautiful state at the time of distribution and product display.

Hereinafter, embodiments of the polypropylene antifogging film of the present invention will be described.
The polypropylene antifogging film in the present invention has a base material layer mainly composed of polypropylene resin and a heat-sealing layer mainly composed of polyolefin resin formed on at least one surface of the base material layer. It is a polypropylene film comprising a laminate of more than one layer and having excellent antifogging properties and high laminate strength.

  The polypropylene resin suitable for forming the base material layer of the polypropylene antifogging film in the present invention is not only isotactic polypropylene but also propylene / ethylene copolymer, propylene / butene-1 copolymer, propylene / 1 type (s) or 2 or more types, such as an ethylene butene-1 copolymer and a propylene / pentene copolymer, can be used. In addition, other polyolefin resins such as ethylene / butene-1 copolymer, ethylene / propylene / butene-1 copolymer, ethylene / acrylic acid copolymer, ethylene An ionomer obtained by crosslinking an acrylic acid copolymer with a metal ion, polybutene-1, butene / ethylene copolymer, or the like can be mixed and used in part.

  The polyolefin resin suitable for forming the heat-sealing layer of the polypropylene antifogging film in the present invention is a polyolefin resin having a melting point lower than the melting point of the polypropylene resin forming the base layer, preferably And a copolymer of propylene and α-olefin having a melting point of 140 ° C. or less, such as propylene / ethylene copolymer, propylene / butene-1 copolymer, propylene / ethylene / butene-1 copolymer, propylene / pentene. 1 type, or 2 or more types, such as a copolymer, can be used. For example, ethylene / butene-1 copolymer, ethylene / propylene / butene-1 copolymer, ethylene / acrylic acid copolymer, ethylene -An ionomer obtained by crosslinking an acrylic acid copolymer with metal ions, polypropylene, polybutene-1, It can be used alone or in combination of two or more of such ten-ethylene copolymer. Further, by using a copolymer having a lower melting point, excellent low temperature sealing property and high sealing strength can be achieved.

  At least one surface of the polypropylene antifogging film of the present invention comprises a layer having antifogging properties and a water-based ink adhesion surface layer having a laminate strength of a water-based ink printing layer of 100 g / 15 mm or more. Here, the peeling interface when the laminate strength is measured is between the water-based ink printing layer and the water-based ink adhesion surface layer of the polypropylene antifogging film.

  More specifically, when the water-based ink adhesion surface layer on one surface of the polypropylene antifogging film of the present invention is printed with water-based ink, the laminate strength with the printed surface is 100 g / 15 mm width or more, preferably 120 to 200 g / It is 15 mm wide.

  Such a water-based ink adhesion surface layer has good wettability of the water-based ink, good ink transfer from the printing roll, and excellent adhesion to the water-based ink, so that the water-based ink has high peel resistance.

  The water-based ink adhesion surface layer has an ink residual ratio of 60% or more, preferably 80% or more when printed with water-based ink and evaluated by a tape peeling test.

  In the present invention, the water-based ink suitable for printing on the surface of the water-based ink adhesion surface layer can be used without particular limitation as long as the amount of the organic solvent in the ink at the time of use is 30% by weight or less. The dispersion medium used in the water-based ink may be any of water-soluble type, colloidal dispersion type, and emulsion type. As the resin, shellac, rosin modified resin, acrylic resin, styrene-maleic acid resin, styrene- An acrylic resin, a polyester resin, a polyurethane resin or the like can be used alone or as a mixture. As the pigment, organic and inorganic pigments can be used without any limitation, and various auxiliary agents such as a dispersant can be optionally added. In addition to water, ethanol, isopropyl alcohol, n-propyl alcohol, or the like can be used as the solvent for the ink.

  The method of gravure printing with water-based ink on the water-based ink adhesion surface layer of the polypropylene antifogging film of the present invention is not particularly limited, and a known method can be used, but the film of the present invention uses multicolor gravure printing. This is particularly effective when

  In addition, the water-based ink adhesion surface layer on one surface of the polypropylene anti-fogging film of the present invention has excellent adhesion to water-based ink, so when printed with water-based ink and evaluated by a tape peeling test, the film surface The ink residual property is good, and the ratio is 60% or more, preferably 80% or more.

  At least one surface of the polypropylene anti-fogging film of the present invention needs to have anti-fogging properties, and therefore, it is usual to include an anti-fogging agent in at least the resin forming the base layer. . During film production, a film may be produced by adding an antifogging agent only to the resin forming the base layer, and the antifogging agent is applied to both the resin forming the base layer and the resin forming the heat fusion layer. May be blended. Even in the former case, the antifogging agent in the resin that forms the base layer is transferred to the heat-sealing layer sequentially during film production and storage after film formation. An antifogging agent is present in the layer, and then bleeds out to the surface of the heat-sealing layer so that the surface of the heat-sealing layer has antifogging properties. When this polypropylene anti-fogging film is used as a package for fresh products, the inner surface of the package, for example, the surface of the heat-sealing layer on the side in contact with fresh products such as fruits and vegetables, fresh products are stored in a packaged state. There must be an antifogging agent that exhibits antifogging properties during the distribution period. That is, the polypropylene anti-fogging film of the present invention not only increases the commercial value by preventing the fogging phenomenon on the side surface of the package, but also prevents water rot of the package contents due to water droplets formed by the progress of the clouding. But anti-fogging is an extremely important property. And the effect can be exhibited when the perishable goods characterized by continuing physiological action after a harvest are made into a packaging object. And in order to maintain excellent anti-fogging properties in the long term in the distribution process, the packaging body is desired to be stored in a room temperature atmosphere rather than frozen storage, considering the temperature change during storage or distribution. The anti-fogging agent that exhibits anti-fogging properties continuously in the course of repeating the temperature change between 5 and 30 ° C. is present on the surface of the heat-sealing layer of the polypropylene anti-fogging film forming the package. It is desirable.

  Examples of the antifogging agent used for imparting antifogging property to at least one surface of the polypropylene antifogging film of the present invention include polyhydric alcohol fatty acid esters, higher fatty acid amines, and higher fatty acid amides. Typical examples include higher fatty acid amines and amide ethylene oxide adducts. The amount of the antifogging agent present in the film is preferably 0.1 to 10% by weight, particularly preferably 0.2 to 5% by weight in terms of all layers, and is 5.0% by weight or less in the heat-fusible layer forming component. Particularly preferred is 0.1 to 1.0% by weight.

  In addition, various additives for improving quality such as slipperiness and antistatic properties, for example, lubricants such as wax and metal soap for improving productivity, plasticity, as long as the effects of the present invention are not impaired. Known heat stabilizers, antioxidants, antistatic agents, UV absorbers, etc., which are usually added to additives, processing aids and polypropylene films, and inorganic or It is also possible to mix organic fine particles in one or both of the base material layer and the heat fusion layer.

  Examples of inorganic fine particles include silicon dioxide, calcium carbonate, titanium dioxide, talc, kaolin, mica, zeolite, etc., and these shapes are not limited to spherical, elliptical, conical, indeterminate, and types, The desired particle size can be used and blended depending on the purpose and usage of the film. Moreover, as organic fine particles, cross-linked particles such as acrylic, methyl acrylate, and styrene-butadiene can be used, and various shapes and sizes can be used in the same manner as inorganic fine particles. Is possible. In addition, various surface treatments can be applied to the surface of these inorganic or organic fine particles, and these can be used alone or in combination of two or more.

  At this time, the film thickness of the polypropylene antifogging film of the present invention varies depending on its use and usage, but the polypropylene film as a packaging film is generally about 5 to 250 μm, particularly about 10 to 100 μm. From the viewpoint of mechanical strength and transparency, it is more preferably about 15 to 60 μm. In addition, the thickness of the heat-sealing layer (the total thickness when the heat-sealing layers are provided on both surfaces of the base material layer) is usually preferably about 0.5 to 10 μm. The thickness ratio is not particularly limited, but is usually about 1/50 to 1/3 of the total thickness of the polypropylene antifogging film of the present invention. If the thickness ratio of the heat-sealing layer is smaller, the heat seal strength becomes insufficient and the reliability as a package is lacking. In addition, if the thickness ratio of the heat-sealing layer is larger, the ratio of the base material layer portion is smaller, so the entire polypropylene anti-fogging film is lost, and the shape of the package after filling with fresh products is unstable. Lack of practicality.

  The film forming conditions of the polypropylene antifogging film of the present invention may be extruded and stretched at a temperature and a magnification to obtain desired film properties, and are not different from the film forming conditions in the case of a general polypropylene film. For example, it can be obtained by stretching a sheet obtained by solidifying a resin composition melt-extruded at an extrusion temperature of 150 to 300 ° C. with a cooling roll of 10 to 100 ° C.

  The polypropylene antifogging film of the present invention is a laminated film, and the laminating method is to melt and knead the resins forming the heat-sealing layer and the base material layer from separate extruders, and laminate them in a T die. Extruding from is a preferred embodiment. In the stretching step, the film can be stretched at an area magnification of about 8 to 50 times, preferably about 10 to 40 times. Moreover, the stretching method of the obtained laminated film does not ask uniaxial stretching and biaxial stretching, and also in the case of biaxial stretching, it implements by simultaneous biaxial stretching method, sequential biaxial stretching method, inflation method, etc. Although sequential biaxial stretching is common.

  As typical conditions for performing sequential biaxial stretching, first, stretching is performed about 3 to 8 times between rolls having a circumferential speed difference heated to about 100 to 150 ° C. in the longitudinal direction, and then the tenter in the width direction. The film is stretched about 4 to 10 times at a temperature of about 140 to 170 ° C. using a stretching machine. Then, after performing a heat setting process at the temperature of 150-170 degreeC, the method of winding up can be illustrated.

  In the polypropylene anti-fogging film of the present invention, the surface layer of the water-based ink adhesion surface activation treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, flame treatment, etc. in a nitrogen concentration atmosphere higher than the nitrogen concentration in the atmosphere. Preferably, it can be obtained by corona discharge treatment. In order to obtain a water-based ink adhesion surface layer, surface activation treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, and flame treatment is carried out in an atmosphere of nitrogen gas (nitrogen gas concentration of 99.99% or more) substantially. Is particularly preferred. At this time, film speed, distance between electrodes, roll temperature before processing, ambient temperature, processing power, etc. can be set as processing conditions. When the atmosphere for performing the surface activation treatment is in the air, that is, when the oxygen concentration is 21%, the obtained treated surface does not have sufficient adhesion to the water-based ink, and the water-based ink is removed or repelled. Such problems are likely to occur, which is not preferable.

  In order to improve the adhesiveness of the water-based ink in the present invention, there is no particular limitation as to the method of performing the surface activation treatment on the film surface in a nitrogen concentration atmosphere higher than the nitrogen concentration in the atmosphere. You may carry out by what is called an in-line process performed in a manufacturing process, and you may carry out by what is called an off-line process which processes the manufactured film as a post process. However, in consideration of cost and simplicity, inline processing is preferable.

  Further, in the polypropylene anti-fogging film of the present invention, in order to have at least one surface of the anti-fogging property, a laminated film containing an anti-fogging agent in at least a base material layer is subjected to normal corona discharge treatment, plasma. Surface activation treatment such as treatment, ultraviolet irradiation treatment, flame treatment, etc., preferably corona discharge treatment is preferred, and the treatment may be either inline treatment or offline treatment, but considering cost and simplicity Inline processing is preferred.

  The water-based ink adhesion surface layer of the polypropylene anti-fogging film of the present invention has good wettability of water-based ink, good ink transfer from a printing roll, excellent print quality, and good adhesion with water-based ink. From this, the peel strength of water-based ink is large, the environment is not polluted by an organic solvent during film printing, and the other surface is a surface having anti-fogging properties. In particular, not only does the inner surface of the bag become cloudy when used on the inner surface of the bag when packaging fresh food, but also the food during the display of the bag printed with aqueous ink on the outside The organic solvent is not transferred to the contents from the opening of the packaging or the like, and the display environment is not adversely affected.

  The polypropylene anti-fogging film of the present invention can be further used after embossing, coating, printing, extrusion lamination, and other resin film, paper, cloth, etc., depending on the purpose.

  Next, the contents and effects of the present invention will be described with reference to examples, but the present invention is not limited to the following examples without departing from the gist thereof. In addition, the measuring method of the characteristic value in this specification is as follows.

(1) Adhesiveness of water-based ink (lamination strength with printing surface)
On the film surface, gravure printing with an ink amount of 2 g / m ² was performed at a speed of 50 m / min using a gravure printing machine (manufactured by Mitani Iron Works). The ink used at this time is a water-based ink (manufactured by Toyo Ink Manufacturing Co., Ltd .: trade name Akwa Ecole JW224R63T white). Subsequently, 3 g / m ^{2 of} a polyether polyurethane adhesive (manufactured by Toyo Morton Co., Ltd .: trade name Ad Coat) was applied on the printed film, and then a corona of a sealant substrate (Toyobo Co., Ltd .: Pyrene P1128 20 μm). The laminate was bonded to the discharge treated surface and subjected to aging treatment at 40 ° C. for 72 hours to obtain a printed and laminated film. The laminate strength of this laminate film was evaluated.
Using a tensile tester (product name: Tensilon UTM, manufactured by Toyo Sokki Co., Ltd.), the laminate sample was gripped with the sealant and film, and measured for T-peel strength (water-based ink printed layer and polypropylene-based anti-corrosion). The value at the time of peeling between the water-based ink adhesion surface layer of the cloudy film). This value was taken as the laminate strength. The tensile speed was 200 mm / min.

(Tape peeling test)
On the film surface, gravure printing with an ink amount of 2 g / m ² was performed using a gravure printing machine (manufactured by Mitani Iron Works). The ink used at this time is a water-based ink (manufactured by Toyo Ink Manufacturing Co., Ltd .: trade name Akwa Ecole JW224R63T white). A grid (2 mm square x 25 squares) was applied to this printed surface and left in an atmosphere at 23 ° C. for 5 minutes, and then a Nichiban cello tape (registered trademark) 18 mm width was pasted. After pressing from above with a pressing roller, the cellophane tape was peeled off at a speed of 10 m / min in the 90-degree angle direction, and the peeled portions were counted and evaluated in four stages. The evaluation is an average value obtained 10 times.
No more than 5 cross-section peeling parts (ink residual ratio 80% or more)
〜１０ 6-10 (ink residual ratio 60% or more)
１５ 11-15 (ink residual ratio 40% or more) ・ ・ ・ △
以上 More than 16 ・ ・ ・ ×

(2) Antifogging property It measured in the following order.
1) Put 300 mL of hot water at 50 ° C. into a 500 mL upper opening container.
2) Seal the container opening with the film with the antifogging measurement surface of the film facing inward.
3) Leave in a cold room at 5 ° C for 12 hours.
4) After leaving in a cold room at 5 ° C, move to a 30 ° C environment and leave for 12 hours.
5) After the operation of 4) was repeated for 2 days, the dew adhesion state on the film measurement surface was evaluated in 4 stages.
No dew on the entire surface (zero adhesion area) ・ ・ ・ ・ ◎
Slight dew adhesion (up to 1/4 adhesion area) ・ ・ ・ ・ ○
Some dew adhesion (up to 1/2 of the adhesion area)
Dew adhesion (more than 1/2 adhesion area) ・ ・ ・ ・ ×

(3) Thermal contraction rate It measured at 120 degreeC x 5 minutes according to JIS-C-2318.

Example 1
A resin in which 1 part by weight of an antifogging agent POE (2) stearylamine-mono-stearate is blended with 100 parts by weight of a polypropylene homopolymer (MI = 2.5 g / 10 min) as a base material layer from one extruder ( A) was melt-extruded at a resin temperature of 280 ° C., and propylene-ethylene-butene copolymer (MI = 10 g / 10 min, ethylene component 2%, butene component 20%) as a heat fusion layer by the other extruder. Copolymer) A resin (B) containing 100 parts by weight of an antifogging agent stearic acid monoglycerin ester is melt-extruded at a resin temperature of 220 ° C., divided into two, and superimposed on both sides of the base material layer, Laminate and extrude in a T-die so that the thickness ratio is thermal fusion layer / base material layer / thermal fusion layer = 0.5 / 19 / 0.5, and solidify by cooling with a cooling roll at 30 ° C. An unstretched sheet was obtained. Subsequently, the metal roll heated to 130 ° C. was stretched 4.7 times in the longitudinal direction using the difference in peripheral speed, and further introduced into a tenter stretching machine, and stretched 9.5 times in the transverse direction. . The preheating part temperature of the tenter stretching machine was 170 ° C., and the stretching part temperature was 155 ° C.

Furthermore, in the latter half of the tenter stretching machine, after heat setting was performed at 160 ° C., a nitrogen gas atmosphere (nitrogen gas concentration 99.99%) was formed on the surface of the heat fusion layer (A) (ink adhesion surface layer forming side). Corona discharge treatment (A) (watt density: 0.27 KW / m ² / min) using a corona discharge treatment machine manufactured by Kasuga Denki Co., Ltd. was performed, and then the heat fusion layer (B) on the opposite side of the treated surface was exposed to the atmosphere. Under an atmosphere, a corona discharge treatment (B) (watt density: 0.27 KW / m ² / min) using a corona discharge treatment machine manufactured by Kasuga Denki Co., Ltd. was performed, and the film was wound with a film winder to obtain a polypropylene film. The final film thickness was 20 μm. The obtained film had a heat shrinkage rate of 4.0%.

(Comparative Example 1)
In Example 1, the corona discharge treatment was performed except that both the surface of the heat fusion layer (A) and the surface of the heat fusion layer (B) of the film were performed in an air atmosphere (nitrogen gas concentration 79%, oxygen concentration 21%). A film was formed under the same conditions as in Example 1 to obtain a polypropylene film. The obtained film had a heat shrinkage of 4.1%.

(Comparative Example 2)
In Example 1, a film was formed under the same conditions as in Example 1 except that the resin for forming the base material layer and the resin for forming the heat-sealing layer were not mixed with an antifogging agent to obtain a polypropylene film. The obtained film had a heat shrinkage rate of 4.0%.

(Comparative Example 3)
In Comparative Example 1, a film was formed under the same conditions as in Comparative Example 1 except that the resin for forming the base material layer and the resin for forming the heat fusion layer were not blended with an antifogging agent to obtain a polypropylene film. The obtained film had a heat shrinkage rate of 4.0%.

(Example 2)
Resin temperature of 280 ° C. with a resin (A) in which 1 part by weight of an antifogging agent glycerin monostearate is blended with 100 parts by weight of a polypropylene homopolymer (MI = 2.5 g / 10 minutes) as a base material layer from one extruder. And melt-extruded to 100 parts by weight of propylene-ethylene-bran copolymer (MI = 10 g / 10 min, copolymer of ethylene component 2%, bran component 20%) as a heat-fusible layer by the other extruder. Resin (B) containing 0.5 parts by weight of the glycerin monostearate agent is melt extruded at a resin temperature of 220 ° C., and the thickness ratio in the T-die is substrate layer / heat-sealed layer = 2/23. Then, they were laminated and extruded, and cooled and solidified with a cooling roll at 30 ° C. to obtain a two-layer unstretched sheet. Subsequently, the metal roll heated to 130 ° C. was stretched 4.7 times in the longitudinal direction using the difference in peripheral speed, and further introduced into a tenter stretching machine to stretch 9.5 times in the transverse direction. . The preheating part temperature of the tenter stretching machine was 170 ° C., and the stretching part temperature was 155 ° C.

Furthermore, in the latter half of the tenter stretching machine, after heat setting at 160 ° C., Kasuga Denki Co., Ltd. in a nitrogen gas atmosphere (nitrogen gas concentration 99.99%) on the surface of the base material layer (ink adhesion surface layer forming side) Was subjected to corona discharge treatment (A) (watt density: 0.27 KW / m ² / min) using a corona discharge treatment machine, and then the surface of the heat-fusible layer (opposite side of the above treated surface) in the atmosphere A corona discharge treatment (B) (watt density: 0.27 KW / m ² / min) was performed by a corona discharge treatment machine manufactured by a company, and the film was wound up by a film winder. The final laminated film thickness was 25 μm. The obtained film had a heat shrinkage of 4.2%.

(Comparative Example 4)
In Example 2, the corona discharge treatment was carried out except that the surface of the base material layer (A) and the surface of the heat-sealing layer (B) of the film were performed in an air atmosphere (nitrogen gas concentration 79%, oxygen concentration 21%). Film formation was performed under the same conditions as in No. 2 to obtain a polypropylene film. The obtained film had a heat shrinkage of 4.2%.

(Comparative Example 5)
In Example 2, a film was formed under the same conditions as in Example 2 except that the resin for forming the base material layer and the resin for forming the heat fusion layer were not blended with an antifogging agent to obtain a polypropylene film. The obtained film had a heat shrinkage of 4.2%.

(Comparative Example 6)
In Comparative Example 4, a film was formed under the same conditions as in Comparative Example 4 except that the resin for forming the base material layer and the resin for forming the thermal fusion layer were not blended with an antifogging agent to obtain a polypropylene film. The obtained film had a heat shrinkage of 4.2%.

  Table 1 shows the evaluation results of the films obtained in Example 1, Comparative Examples 1, 2, and 3, Example 2, Comparative Examples 4, 5, and 6.

  As mentioned above, although the polypropylene type anti-fogging film excellent in printability of the present invention has been described based on a plurality of examples, the present invention is not limited to the configuration described in the above examples, and in each example. The configurations can be appropriately changed within a range not departing from the gist, such as appropriately combining the configurations described.

  The polypropylene anti-fogging film excellent in printability of the present invention is not affected by the excellent anti-fogging properties and transparency inherently possessed, when printed with water-based ink, There is no printing transfer, ink misalignment, or contamination due to friction and adhesion, and the printing surface is excellent in laminating properties, maintaining a beautiful state during distribution and product display, and being suitable for laminating with a printing layer using water-based ink. Since it has, it can be used suitably for the packaging use of fresh goods, and can be suitably used for a wide range of uses such as packaging of a hydrous article.

(A) is a sectional view of an example of the polypropylene antifogging film of the present invention, (B) is a sectional view of another example of the polypropylene antifogging film of the present invention, and (C) is a polypropylene based of the present invention. Sectional drawing of an example of the laminated film which performed printing with water-based ink on the antifogging film, (D) is the cross section of another example of the laminated film which printed with water-based ink on the polypropylene antifogging film of the present invention Figure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material layer 11 Base material layer which has water-based ink adhesion surface layer 2 Heat-fusion layer 21 Heat-fusion layer which has water-based ink adhesion surface layer 3 Water-based ink printing layer 4 Adhesive layer 5 Sealant layer

Claims (6)

  A laminate comprising two or more layers having a base material layer mainly composed of a polypropylene resin and a heat-sealing layer mainly composed of a polyolefin resin formed on at least one surface of the base material layer. A polypropylene-based antibacterial layer comprising a layer having an antifogging property and a water-based ink adhesion surface layer having a laminate strength of a water-based ink printing layer of 100 g / 15 mm or more in a layer constituting the body. Fog film.   2. The polypropylene antifogging film according to claim 1, wherein the water-based ink adhesion surface layer is obtained by subjecting the surface of the film to surface activation treatment in a nitrogen concentration atmosphere higher than the nitrogen concentration in the air.   The polypropylene-based antifogging film according to claim 1 or 2, wherein the thermal shrinkage at 120 ° C for 5 minutes is 10% or less.   4. The polypropylene antifogging film according to claim 1, wherein at least the base material layer contains an antifogging agent.   The polypropylene anti-fogging film according to claim 1, 2, 3, or 4, wherein the heat-sealing layer has a thickness of 0.5 to 10 µm.   A polypropylene antifogging film for packaging fresh products, comprising the polypropylene antifogging film according to claim 1, 2, 3, 4 or 5.

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