JP5994338B2 - Heat-sealable film and method for producing heat-sealable film - Google Patents

Description

  The present invention relates to a heat-sealable film. Especially heat-sealing films for packaging foods, beverages, pharmaceuticals, cosmetics, chemicals, etc. More specifically, for lids for containers such as yogurt, jelly, pudding, syrup, and retort foods such as porridge and soup The present invention relates to a heat-sealable film used for film materials for storage containers such as packaging bags, liquids such as chemicals and pharmaceuticals, semi-solids, and gel substances.

  Ordinary lids and packaging bags are difficult to remove due to the contents adhering thereto, and often cause waste or dirt of the contents. In addition, when a fluorine material or silicone is used, although it has water repellency and adhesion prevention effects, it has poor heat sealing properties and is difficult to use for container packaging materials such as lid materials and packaging bags.

  In order to solve these problems, various proposals as shown in the following Patent Documents 1 to 3 have been made.

  In Patent Document 1, the heat seal layer on the innermost surface is a polyolefin to which a hydrophobic additive such as fatty acid ester or fatty acid amide having an adhesion preventing effect is added. It is known that the amount of precipitation greatly fluctuates and is applied to stability, and the desired performance is not sufficiently obtained.

  In Patent Document 2, it is not added to the heat seal layer, but an adhesion preventing layer is additionally formed on the inner surface (the innermost surface), and a porous structure having a three-dimensional network structure is formed by hydrophobic particles. It shows an excellent anti-adhesion effect.

  However, this anti-adhesion layer is still inferior in heat resistance, and when the high temperature environment and drying time are prolonged, the hydrophobic particles sink into the hot-melt heat seal layer, thereby eliminating the anti-adhesion effect. There was a problem. In the contents filling process, particularly in the sealing process, these obstruction factors are very troublesome in terms of handling.

  In Patent Document 3, as in Patent Document 2, an adhesion preventing layer is provided on the sealant layer. By using wet silica particles with a large average particle size in the adhesion prevention layer, the precipitation of wet silica is reduced, and the adhesion prevention function can be maintained even when the high temperature environment and the drying temperature at the time of application are prolonged. . However, since the particle diameter is large, there is a problem that the particle is detached from the adhesion preventing layer.

  Known documents are shown below.

JP 2002-37310 A Japanese Patent No. 4348401 Japanese Patent No. 4668352

The present invention has been made in view of the above circumstances, and has a heat-sealing film having excellent water repellency and milk repellency while maintaining good heat-sealability, and has the effect of reducing the remaining amount of contents and preventing adhesion. It is an issue to provide.

The invention according to claim 1 of the present invention is a heat-sealable film comprising at least a base material layer, a sealant layer on at least one surface of the base material layer, and a water repellent layer,
The sealant layer has an uneven surface, and the water-repellent layer made of hydrophobic particles and a thermoplastic resin is provided on the uneven surface.
The heat-sealable film is characterized in that the thermoplastic resin is spherical and dispersed on the surface of the sealant layer, and the hydrophobic particles are dispersed on the surface of the thermoplastic resin.

The invention according to claim 2 of the present invention is the heat-sealing film according to claim 1 , wherein the unevenness formed on the surface of the sealant layer is formed in a lattice shape.

The invention according to claim 3 of the present invention, the thermoplastic resin is a polyolefin, ethylene-vinyl acetate copolymer, acrylic resin, according to claim 1, characterized in that it is any one or a mixture of styrene-butadiene rubber or The heat-sealable film according to claim 2 .

The invention according to claim 4 of the present invention is a method for producing a heat-sealable film,
The heat sealable film comprises at least a base material layer, a sealant layer on at least one surface of the base material layer, and a water repellent layer,
The sealant layer has an uneven surface, and the water-repellent layer made of hydrophobic particles and a thermoplastic resin is provided on the uneven surface.
The thermoplastic resin is spherical and dispersed on the surface of the sealant layer, and the hydrophobic particles are dispersed on the surface of the thermoplastic resin,
The method for producing a heat-sealable film , wherein the unevenness and the water-repellent layer formed on the surface of the sealant layer are formed by pressing a stamper .

  The heat sealable film of the present invention has excellent water repellency and milk repellency while maintaining good heat sealability, and has the effect of reducing the remaining amount of contents and preventing adhesion.

It is explanatory drawing which showed typically the layer structure of an example of the heat-sealable film of this invention in the cross section. It is explanatory drawing which showed typically the process of forming the water-repellent layer of an example of the heat-sealable film of this invention.

  Hereinafter, modes for carrying out the present invention will be described.

  FIG. 1 is an explanatory view schematically showing in cross section the layer structure of an example of the heat-sealable film of the present invention.

  In the heat-sealable film 100 according to an example of the present invention, the base material layer 1 and the sealant layer 2 are laminated from the outer layer side. The sealant layer 2 has an uneven surface, and the water-repellent layer 3 is formed on the uneven surface.

The water repellent layer 3 is composed of a spherical thermoplastic resin 4 and hydrophobic particles 5, and the thermoplastic resin 4 is dispersed so as to be buried in the surface of the sealant layer 2. Further, hydrophobic particles 5 are dispersed on the surface of the spherical thermoplastic resin 4. The irregularities formed on the surface of the sealant layer 2 are formed as peaks and valleys, and the valleys are formed in a lattice shape.

  The surface of the water-repellent layer 3 is provided with irregularities having a height of 5 to 500 μm and a pitch of 20 to 1,000 μm, and the surface on which the water-repellent agent is disposed covers the almost entire surface with the hydrophobic particles 5 on the outermost surface. It is coated like this.

  The base layer 1 is disposed on the front side of the heat-sealable film 100 and is a single layer of paper or a plastic film such as polyethylene terephthalate, polyethylene, polypropylene, polyamide, polycarbonate, polyvinyl chloride, cellulose acetate, cellophane, etc. Alternatively, a laminate of these can be used. Moreover, since it is the front side of the heat-sealable film 100, it prints normally suitably and the designability is provided.

  The sealant layer 2 is preferably a heat seal varnish, a polyethylene film sealant, or an extruded polyethylene resin.

  Components of heat seal varnish include acrylic resin, urethane resin, melamine resin, amino resin, epoxy resin, polyethylene resin, polystyrene resin, polypropylene resin, polyester resin, cellulose resin, vinyl chloride resin, polyvinyl alcohol, ethylene vinyl acetate copolymer Coalescence etc. can be used.

  For the lamination of the sealant layer 2, a known method such as gravure coating, bar coating, kiss reverse coating, die coating, doctor blade coating, brush coating, dip coating, spray coating, spin coating, extrusion lamination, etc. can be employed.

  A barrier layer may be provided between the base material layer 1 and the sealant layer 2. The barrier layer is used for the purpose of imparting gas barrier properties, and a vapor deposition film in which an inorganic oxide such as silica or alumina is vapor deposited is mainly used. As the film at this time, polyethylene terephthalate, polyethylene, polypropylene, polyamide, polycarbonate, polyvinyl chloride, cellulose acetate, cellophane, or the like can be used. Furthermore, the vapor deposition film etc. which vapor-deposited the metal for the purpose of providing designability can also be used. Furthermore, a metal foil can be used.

  As the spherical thermoplastic resin 4, polyolefin such as polyethylene having a particle diameter of 1 to 5 μm, ethylene vinyl acetate copolymer, acrylic resin, and styrene butadiene rubber can be used. Preferably, polyethylene or ethylene vinyl acetate copolymer having an average particle diameter of 1 to 3 μm is used. Here, the average particle diameter is the particle diameter at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method.

  For the hydrophobic particles 5, for example, at least one of particulate silica, alumina, titania and the like can be used. Of these, hydrophobic silica particles can be preferably used.

  Further, as the hydrophobic silica particles, hydrophobic silica particles having trimethylsilyl group, triethylsilyl group, butyldimethylsilyl group, triisopropylsilyl group, butyldiphenylsilyl group, dimethylsiloxane group, dimethylpolysiloxane group on the surface can be used. However, in particular, hydrophobic silica particles having a trimethylsilyl group are preferable in terms of obtaining superior adhesion preventing properties.

  The average particle diameter of the primary particles is preferably 3 to 100 nm from the viewpoint of processability and repellency. Preferably 5-20 nm is good. The hydrophobic silica particles may contain aggregates (secondary particles) in addition to the primary particles.

  Hereinafter, the manufacturing method of the heat-sealable film 100 of an example of this invention is demonstrated.

  FIG. 2 is an explanatory view schematically showing a process of forming a water repellent layer as an example of the heat-sealable film of the present invention.

  First, the base material layer 1 and the sealant layer 2 are laminated, and the paste 6 is created. As described above, known methods such as gravure coating, bar coating, kiss reverse coating, die coating, doctor blade coating, brush coating, dip coating, spray coating, spin coating, and extrusion lamination are used as the lamination method.

  Separately, a dispersion liquid of spherical thermoplastic resin 4 and hydrophobic particles 5 is prepared to prepare a coating liquid 7 that becomes a water repellent layer.

  The coating liquid 7 is put into the ink pan 8, supplied to the transfer plate 10 with the stamper formed into a roll shape through the coating liquid supply roll 9, passed through the strip 6 between the transfer plate 10 and the nip roll 11, and repelled to the strip 6. The water layer 3 is laminated. At this time, since the unevenness is provided on the surface of the transfer plate 10 in which the stamper is rolled, the unevenness is provided on the surfaces of the sealant layer 2 and the water repellent layer 3.

  Although the coating liquid 7 is supplied to the transfer plate 10 by the coating liquid supply roll 9, it may be supplied by a die or a spray. Thus, if the stamper is the roll-shaped transfer plate 10, roll-to-roll processing can be performed by continuously and uniformly applying the coating liquid 7 onto the transfer plate 10.

  At this time, the transfer plate 10 is heated to a certain temperature, and the water-repellent layer 3 is pressure-bonded and transferred to the paste 6. Further, the shape of the surface of the transfer plate 10 in which the stamper is rolled gives a size for satisfying the height and pitch of the water repellent layer 3, but the pattern is hemispherical, pyramidal lattice, trapezoidal Any material can be used as long as it can be transferred sufficiently during processing, such as a lattice shape, a line shape, a needle shape, a conical shape, and a turtle shell shape.

  When the pitch of the water-repellent layer 3 exceeds 1 mm, the effect of large unevenness tends to be reduced, and it tends to adhere to the surface against water droplets containing a small amount of oil and fat. Therefore, 20-1,000 micrometers is preferable. Further, when the height is lower than 5 μm, the drop-falling effect is lowered. On the other hand, when the height is 500 μm or more, the droplets adhering to the valley are easily caught and the fallability is deteriorated. Preferably, it is between 10-100 micrometers.

  Since the transfer plate 10 is heated to a constant temperature by manufacturing as described above, the sealant layer 2 is heated to be in a semi-molten state, and the coating liquid 7 placed on the stamper is placed on the sealant layer 2. While being dried, it is pressure-bonded / transferred to the paste 6 and adheres firmly so as to sink.

  In addition, since the uneven surface is obtained by pressing with a stamper, the hydrophobic particles 5 are attached so as to be embedded in the sealant layer 2 and the spherical thermoplastic resin 4, so that the physical adhesion is strong and the water repellent layer 3. A surface that is difficult to peel off is obtained. Furthermore, the adhesiveness between the hydrophobic particles 5 and the sealant layer 2 can be further enhanced by the thermoplastic resin 4, and the water repellent layer 3 itself has a strong cohesive force, so that the structure is not easily broken.

  Specific examples of the present invention will be described below.

<Example 1>
A polyethylene terephthalate film having a thickness of 12 μm was used as the base material layer 1, and a barrier layer aluminum foil of 7 μm was dry-laminated and bonded to the base material layer 1. Acrylic resin heat sealant (A450 manufactured by DIC Corporation), which becomes the urethane-based anchor coat agent (A970 manufactured by DIC Corporation) and sealant layer 2, is applied to the aluminum foil surface at a dry coating amount of 3 g / m ² and 10 g / m respectively. The paste 6 which becomes a heat-sealable base material was created by coating with m ² .

  Separately, a coating liquid 7 to be the water repellent layer 3 is prepared. First, a dispersion A prepared by dispersing an ethylene vinyl acetate copolymer (average particle size 2 μm) of thermoplastic resin 4 in water to a solid content of 50 wt%, and average particles obtained by subjecting hydrophobic particles 5 to trimethylsilyl treatment. Dispersion B prepared by dispersing silica fine particles having a diameter of 10 nm in ethanol to a solid content of 10 wt% and methanol as a solvent are mixed at a weight ratio of 1/2/7 so that the total solid content becomes 5 wt%. Mixed.

As shown in FIG. 2, the coating solution 7 was transferred to a transfer plate 10 (a square frustum-shaped lattice plate having a plate depth of 85 μm at a pitch of 100 L / inch) heated to 80 ° C. at a coating amount of 1.5 g / m ² . Further, while transferring to the surface of the sealant layer 2 of the sample 6, 2 tons of pressure was applied with the nip roll 11, and the surface of the sealant layer 2 of the sample 6 was coated with the water repellent layer 3, while forming irregularities on the surface. The heat-sealable film of Example 1 was prepared.

<Example 2>
As the base material layer 1, a paper having a basis weight of 80 g and a polyethylene terephthalate film 12 μm laminated is prepared, and a hot melt agent (DX65TS manufactured by DIC Corporation) is applied to the surface of the polyethylene terephthalate film at a coating amount of 15 g / m ^2. And the sealant layer 2 was provided and the paste 6 used as a heat-sealable base material was created.

  Except that the heating temperature of the transfer plate 10 was set to 80 ° C., the surface of the paste 6 was made uneven while applying the water repellent layer 3 to the surface of the sealant layer 2 of the paste 6. The heat-sealable film of Example 2 was formed.

<Example 3>
A heat-sealable film of Example 3 was prepared in the same manner as in Example 1 except that the transfer plate 10 having a pitch of 55 L / inch and a plate depth of 200 μm was used.

  Below, the comparative example of this invention is demonstrated.

<Comparative Example 1>
The coating liquid 7 was applied with a normal gravure coater at a coating amount of 1.5 g / m ² , dried under the condition of 80 ° C. for 10 seconds, and the water-repellent layer 3 was provided without forming irregularities on the surface. In the same manner as in Example 1, a heat sealable film of Comparative Example 1 was prepared.

<Comparative example 2>
Dispersion B in which silica fine particles having an average particle size of 10 nm subjected to trimethylsilyl treatment were dispersed in ethanol and adjusted to a solid content of 10 wt% without using dispersion A in which thermoplastic resin 4 was dispersed in water, A heat-sealable film of Comparative Example 2 was prepared in the same manner as in Example 1 except that a coating solution in which methanol was mixed at a weight ratio of 1/1 and the total solid content was 5 wt% was used. did.

<Test method>
The heat-sealable films of Examples and Comparative Examples were tested and evaluated by the following methods.

<Seal strength>
The three water-repellent layers of the heat-sealable film were opposed to each other and heat-sealed under heat seal conditions of 210 ° C. × 0.2 MPa × 3.0 sec, and the seal strength was measured based on JIS Z0238. The results are summarized in Table 1.

<Contact angle>
Water drops and yogurt (plain sugar-free) were dropped on the water-repellent layer 3 surface of the heat-sealing film, and the contact angles were measured. The results are summarized in Table 1.

<Tumble angle>
Lay the water-repellent layer 3 side of the heat-sealing film flat and place water drops and yogurt (plain sugar-free) on the water-repellent layer 3 face, tilt the heat-sealing film, And the angle at which the yogurt droplets began to roll. The results are summarized in Table 1.

<Gakushin Examination>
The surface of the water-repellent layer 3 of the heat-sealable film is subjected to a 10-way reciprocation test at a load of 200 g, and then yogurt (plain sugar-free) is dropped on the surface of the water-repellent layer 3 to repel the yogurt droplets. The repellency was evaluated with ◯ as the case and the cross with the yogurt droplet attached as X. The results are summarized in Table 1.

以下に、実施例と比較例との比較結果について説明する。

Below, the comparison result of an Example and a comparative example is demonstrated.

<Comparison result>
The heat-sealable films of Example 1, Example 2, and Example 3 all have good seal strength, contact angle, falling angle, and repelling property after the Gakushin test. It has been found that it has excellent water repellency and milk repellency while maintaining sealing properties, and has the effect of reducing the remaining amount of contents and preventing adhesion.

  On the other hand, the heat-sealable film of Comparative Example 1 has a yogurt falling angle of <30 ° and does not fall unless it is attached and tilted greatly, and the adhesiveness is higher than in Examples 1, 2, and 3. Moreover, in the heat-sealable film of Comparative Example 2, when it is repeated, the falling angle of yogurt becomes large, and the adhesiveness becomes high.

  As for the repellency after the Gakushin test, in both Comparative Example 1 and Comparative Example 2, it was found that yogurt was adhered and there was no resistance to friction.

  As described above, the heat-sealable film of the present invention is imparted with high water repellency and milk repellency, and further maintains heat-sealability. It is possible to provide a lid material and a packaging material that prevent contamination due to the above.

  Then, by applying and pressing the coating liquid for applying the water repellent layer with a stamper having unevenness on the surface, moderate unevenness can be created on the heat-sealable film, and hydrophobic particles having a high water repellent effect The water-repellent layer containing can be firmly attached to the heat-sealable substrate. Further, by adding a thermoplastic resin to the coating liquid for applying the water repellent layer, the adhesion between the sealant layer and the hydrophobic particles is further increased, and the water repellent effect is easily maintained.

DESCRIPTION OF SYMBOLS 100 ... Heat sealing film 1 ... Base material layer 2 ... Sealant layer 3 ... Water-repellent layer 4 ... Thermoplastic resin 5 ... Hydrophobic particle 6 ... Paste 7 ..Application liquid 8 ... Ink pan 9 ... Application liquid supply roll 10 ... Transfer plate 11 ... Nip roll

Claims (5)

A heat-sealable film comprising at least a base material layer, a sealant layer on at least one surface of the base material layer, and a water-repellent layer,
The sealant layer has an uneven surface, and the water-repellent layer made of hydrophobic particles and a thermoplastic resin is provided on the uneven surface .
A heat-sealing film , wherein the thermoplastic resin is spherical and dispersed on the surface of the sealant layer, and the hydrophobic particles are dispersed on the surface of the thermoplastic resin . The heat sealable film according to claim 1 , wherein the unevenness formed on the surface of the sealant layer is formed in a lattice shape. The heat-sealable film according to claim 1 or 2 , wherein the thermoplastic resin is any one of a polyolefin, an ethylene vinyl acetate copolymer, an acrylic resin, and a styrene-butadiene rubber, or a mixture thereof. In the method for producing a heat-sealable film,
The heat sealable film comprises at least a base material layer, a sealant layer on at least one surface of the base material layer, and a water repellent layer,
The sealant layer has an uneven surface, and the water-repellent layer made of hydrophobic particles and a thermoplastic resin is provided on the uneven surface.
The thermoplastic resin is spherical and dispersed on the surface of the sealant layer, and the hydrophobic particles are dispersed on the surface of the thermoplastic resin,
Method for producing a heat-sealable film, which comprises forming by an uneven and water-repellent layer formed on the surface of the sealant layer, to press working the stamper. The method for producing a heat-sealable film according to claim 4, wherein the stamper is heated and pressed .

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