JP4668352B1 - Contents adhesion prevention lid material and manufacturing method thereof - Google Patents

Abstract

[PROBLEMS] A lid material mainly applied to a container for yogurt packaging, which effectively prevents the content of yogurt from adhering to the back surface of the lid while maintaining good heat sealing and sealing properties. It shall be possible.
An adhesion preventing layer 6 made of hydrophobic fine particles 10 is formed on the outer surface of a heat sealing layer 5 laminated on a base material layer 1. The anti-adhesion layer 6 has hydrophobic wet silica particles having an average particle size of 0.5 to 7.0 μm obtained by imparting hydrophobicity to wet silica particles, and the adhesion amount of the particles is 0.1 to 0.5 g / m ² . Form a uniform thin layer with a certain particle distribution.
[Selection] Figure 1

Description

  The present invention relates to a heat-sealing lid material mainly applied to containers for packaging foods, and more specifically, to prevent adhesion of contents applied to cup-shaped containers for packaging such as yogurt, jelly, pudding, jam, etc. And a manufacturing method thereof.

  This type of heat sealing lid material is generally provided with a heat sealing layer, that is, a heat sealing layer, on an aluminum foil surface side of a base material layer made of a laminate of a base material film and an aluminum foil via an intermediate resin layer. A sealed package is formed by covering the upper opening of a cup-shaped container body filled with an object to be packaged such as yogurt and heat-sealing the peripheral part on the upper edge flange part of the container body.

  Therefore, in such a lid material, good heat-sealing property, sealing property, and appropriate easy peelability for opening are required, and at the same time, the non-adhesiveness of the contents, that is, the lid material on the inner surface side of the container It is desired that the contents can be prevented from adhering to the back surface. If the contents adhere to the back of the lid, fingers, clothes, or the surrounding area may be soiled at the time of opening, waste of the contents will be lost, or it will take time to peel off the contents, and it will also become unclean. This is to cause a disadvantage such as hosting.

  Therefore, conventionally, various proposals as shown in Patent Documents 1 to 6 below have been made for cover materials having a content adhesion prevention performance.

  The prior arts shown in Patent Documents 1 to 3 are those in which a nonionic surfactant or a hydrophobic additive having an adhesion preventing effect, a wax, or the like is added to the heat sealing layer on one side of the base material. Although the layer itself is intended to impart anti-adhesion performance, all of them are still unsatisfactory in terms of the expected content-preventing effect.

  Further, the prior arts of Patent Documents 4 to 5 are such that a content adhesion preventing layer is additionally formed on the outer surface (surface on the container side) of the heat sealing layer. The adhesion preventing layer is made of wax, And a composition with a solid fine particle filler dispersed in the composition. In these prior arts, the content adhesion preventing effect is further improved as compared with the prior arts of Patent Documents 1 to 3, but it is still not sufficient, and in addition, a filler is dispersed in the wax. Therefore, there is a concern that the heat-sealing property of the heat-sealing layer is adversely affected and the sealing property tends to be unstable.

  Furthermore, in the prior art disclosed in Patent Document 6, a porous layer having a three-dimensional network structure is formed on the outer surface of the heat-sealing layer as a content adhesion preventing layer by hydrophobic oxide fine particles such as fine hydrophobic silica. It is to do.

  Although this prior proposal technique can exert a very excellent effect in terms of content adhesion prevention effect, the adhesion prevention effect is impaired when the adhesion prevention layer is inferior in heat resistance and receives an undesirable heat history. There is. That is, as the hydrophobic fine particles, ultrafine hydrophobic oxide fine particles having a primary particle average diameter of 3 to 100 nm, typically silica fine particles produced by a dry method, are used. When applied to the formation of anti-adhesion layers for lid materials with a general hot-melt type heat sealing layer, the heating temperature during drying after coating of the fine particle dispersion in the formation process of the anti-adhesion layer is If it is too high or the drying time is long, the content adhesion preventing effect is significantly impaired. In addition, when filling a container such as yogurt, jelly, pudding or the like, the cover material on standby is exposed to a heat-sealing hot plate, so that the content adhesion preventing effect cannot be sufficiently obtained. For this reason, the process management at the time of manufacture of a lid | cover material and the time of heat sealing is a little troublesome, and there existed a difficulty that handling was difficult.

  When the heat-melt adhesive of the heat-sealing layer is melted by heat during drying or radiant heat from a hot plate that is waiting at the time of heat-sealing, the fine oxide particles become hot-melt adhesive. Or the hot melt agent enters the gaps between the fine particles by capillarity and fills the gaps between the particles, thereby reducing the water-repellent surface area and preventing sufficient adhesion of the contents. It is considered a thing.

JP 2002-37310 A JP 2007-153385 A JP 2008-1000073 A JP 2009-73523 A JP 2009-241943 A Japanese Patent No. 4348401

  In view of the above-described problems in the prior art, the present invention is intended to further improve them, specifically, while maintaining stable and good heat sealing performance, content adhesion prevention performance, particularly heat. Adhesion with the heat-sealing layer of hydrophobic particles having good heat resistance that can maintain excellent content adhesion prevention performance even when exposed to a high temperature at which the sealing layer melts, and exhibiting the adhesion prevention effect It is an object of the present invention to provide an improvement technique capable of improving the stability and sustainability of the content adhesion preventing effect by enhancing the adhesion between the cover material and the container.

In order to achieve the above object, the present invention first presents the following means [1] to [ 3 ] for the content adhesion preventing lid.

[1] It has at least a base material layer and a heat sealing layer,
In the cover material comprising the hot-sealing adhesive, the heat sealing layer contains a wax and an ethylene-unsaturated ester polymer as main components, and contains 30% by weight or more of the ethylene-unsaturated ester polymer .
An adhesion preventing layer on the outer surface of the heat sealing layer;
Said adhesion prevention layer, Ri Do hydrophobic wet silica particles having an average particle size of 2.0~7.0μm imparted with hydrophobic wet silica particles, and the amount of deposition of the hydrophobic wet silica particles in said adhesion prevention layer the contents of adhesion preventing cover member, wherein 0.1 to 1.0 g / ^{m 2} der Rukoto by weight after drying.

[ 2 ] The content adhesion preventing lid material according to [1], wherein the hydrophobic wet silica particles have an oil absorption of 50 ml / 100 g or more.

[ 3 ] The content adhesion preventing lid material according to [1] or [2] , wherein the content of the ethylene-unsaturated ester copolymer in the heat sealing layer is 40 parts by weight or more.

The present invention also presents the means of the following items [4] and [5] with respect to the method for producing the content adhesion preventing lid.

[4] possess at least a substrate layer and the heat sealing layer, the heat sealing layer, wax and ethylene - containing as a main component an unsaturated ester polymer, and the ethylene - unsaturated ester polymer 30 wt% Disperse hydrophobic wet silica particles having an average particle size of 2.0 to 7.0 μm, which is obtained by imparting hydrophobicity to wet silica particles, in an organic solvent on the outer surface of the heat sealing layer of the hot-melt adhesive containing the above. The dispersion prepared in this manner was applied so that the wet silica particle adhesion amount was 0.1 to 1.0 g / m ^{2 by} weight after drying, and the temperature was 80 to 140 ° C. for 5 to 30 seconds. A method for producing a content adhesion preventing lid material, comprising drying under dry conditions to form an adhesion preventing layer.

[ 5 ] The method for producing a content adhesion preventing lid material according to [4] , wherein the temperature under drying conditions after application of the dispersion is 100 to 120 ° C. and the time is 10 to 20 seconds.

In the content adhesion prevention lid material as described in the above items [1] to [ 3 ] according to the present invention, an adhesion prevention layer is separately formed on the outer surface of the heat sealing layer, and the adhesion prevention is performed. Since the layer is made of wet silica particles with hydrophobicity added to the wet silica particles, relatively superior contents adherence with a much smaller amount of adhesion than those using hydrophobic dry silica particles. Develop preventive properties. In addition, it has excellent heat resistance and can maintain high anti-adhesion performance even when exposed to high temperatures. The reason for this is not clear, but can be considered as follows. That is, wet silica particles generally have a micron size larger than dry silica particles, and in the present invention, the average particle size is 2 . By those 0 to 7.0 [mu] m is used, when the heat seal layer is composed of a hot-melt adhesive, be the hot melt adhesive is melted, the hydrophobic silica particles the adhesive layer It is hard to sink. In addition, unlike the case of dry silica, wet silica particles are inherently porous, have a high specific surface area, and have a large pore volume and oil absorption. For this reason, when the heat-sealing layer is melted, the low melting point and low molecular weight components such as wax and rosin contained therein are rapidly adsorbed by the wet silica particles themselves, and the gaps between the particles are filled with the molten hot melt adhesive. To prevent it. Accordingly, the gaps between the particles are maintained, and as a result, the exposed area of the hydrophobic surface of the particles is prevented from being extremely reduced, thereby maintaining a good content adhesion preventing effect. In addition, the wet silica particles are defined in the present invention because they have very strong interparticle bonds that occur during the production process, and maintain the state of the soul-collecting particles even when sheared. In the particles having an average particle diameter of 2.0 to 7.0 μm, nano-sized ultrafine particles, specifically, fine particles having a particle diameter of 100 nm or less are hardly included. For this reason, good adhesion of the hydrophobic particles to the heat sealing layer can be maintained, and the heat sealing performance of the heat sealing layer is not greatly impaired, and the sealing performance and sealing strength of the container are uniform and stable. Excellent performance.

  Furthermore, the above-described effects of the present invention include the most commonly used wax and ethylene-unsaturated ester when the heat sealing layer of the lid body is a packaging container such as yogurt, jelly, pudding, jam, etc. It is particularly effective in the case of a hot melt adhesive mainly composed of a polymer, and further, the content of the ethylene-unsaturated ester polymer is 30% or more, preferably 40% or more. In the case of using a hot melt adhesive having a relatively low content of wax or the like, it can be more remarkably enjoyed.

Moreover, in the manufacturing method of a lid | cover material as described in said [4] [5] item, the heat seal lid | cover material which has the above outstanding effects can be manufactured easily. In particular, the inherent water repellency and hydrophobicity of hydrophobic wet silica particles having a relatively large particle size were maintained well by setting the heating temperature and time in the drying process after the dispersion coating within a specified range. An adhesion preventing layer can be formed.

FIG. 1 is a cross-sectional view showing an outline of a laminated structure of a content adhesion preventing lid material according to the present invention.

  FIG. 1 shows an example of a laminated structure of a content adhesion preventing lid according to the present invention. The lid material includes a base material layer (1) composed of a laminate of a base film layer (2) and a metal foil layer (3), and an outer surface of the base material layer (1) on the metal foil (3) side, A heat sealing layer (5) is provided on the surface facing the inside of the container body when the lid is used via an intermediate resin layer (4). The above laminated structure is the same as that of the conventional lid, and the laminated body including the base material layer (1) and the heat sealing layer (5) will be referred to as a “lid body” here.

  The content adhesion preventing lid material according to the present invention further has an adhesion preventing layer (6) on the outer surface of the heat sealing layer (5) of the lid body.

  The base film layer (2) is arranged on the front side of the packaging container, and the material thereof is a single layer or composite film such as polyester, polyethylene, polypropylene, polyamide, polycarbonate, polyvinyl chloride, cellulose acetate, cellophane, etc. Or what laminated these films on paper etc. can be illustrated. The base film layer (2) is usually appropriately printed (7) to impart design properties.

  The metal foil layer (3) imparts gas barrier properties, light shielding properties, etc., and aluminum foil is often used. In particular, in the case of a lid for a yogurt container, an aluminum foil having a thickness of about 5 to 50 μm is preferably used in order to satisfy light shielding properties and light weight. Moreover, a general adhesive agent is used for lamination | stacking adhesion | attachment with a base film layer (2).

  In addition, as a base material layer (1), it is also possible to use the metal vapor deposition film which vapor-deposited metals, such as a silica and an alumina, to the base film layer (2), without using a metal foil layer (3). .

  The intermediate resin layer (4) is interposed between the base material layer (1) and the heat sealing layer (5), and imparts a predetermined rigidity and cushioning property at the time of heat sealing to the lid material. Provided as needed. Generally, olefin resin such as polyethylene, polypropylene, ethylene (meth) acrylic acid copolymer, ethylene (meth) acrylic acid ester copolymer, polyamide, polyester, polycarbonate, polyvinyl chloride, etc. having a thickness of 5 to 40 μm Used.

  The material of the heat sealing layer (5) is not particularly limited as long as it has good adhesion to the intermediate layer resin layer (4) and the container side, but in particular, a paper / polyethylene container for packaging such as yogurt. For the cover material, it is common and preferable to use a hot melt adhesive. Among hot melt adhesives, the main component is a wax and an ethylene-unsaturated ester copolymer, the balance being a tackifier such as rosin, and further an ethylene-unsaturated ester copolymer such as ethylene- It is desirable to use a hot melt resin composition containing 30% by weight or more, preferably 40% by weight or more of a vinyl acetate copolymer. That is, in the case of a hot melt adhesive having an ethylene-unsaturated ester copolymer content of less than 30% by weight, the content of wax or rosin, which are low melting point components, is relatively increased. The tendency to reduce the heat resistance of the prevention layer becomes stronger. The reason is that the amount of the low melting point component melted and adsorbed on the hydrophobic wet silica particles is increased due to the effect of heat received during drying or heat sealing, and consequently the hydrophobic surface area of the particles is reduced. This is presumably because the adhesion preventing effect may be reduced.

  The thickness of the heat sealing layer is not particularly limited, but is generally about 3 to 100 μm in thickness from the viewpoint of cost, sealing performance, productivity, etc. The range is preferably 50 μm.

  By the way, the anti-adhesion layer (6) which constitutes the main component of the present invention is made hydrophobic by chemically reacting an organic silicon compound with a hydroxyl group on the surface of wet silica particles which are synthetic amorphous silica produced by a wet method. It consists of hydrophobic wet silica particles with added properties.

  Wet silica has more surface silanol groups than dry silica, and even in hydrophobic particles after the surface is hydrophobized with silanes or silicones, it has superior water repellency and hydrophobicity compared to dry silica. Indicates. Also, compared to dry silica particles whose secondary unit is secondary particles, which are aggregates of primary particles without pores, wet silica particles not only have a large particle diameter, but also have a large specific surface area relative to the particle diameter. Also, pore volume and oil absorption are large. These facts are also considered to have greatly contributed to the improvement of the performance of the adhesion preventing layer.

  In order to effectively utilize the properties of such wet silica, the wet silica particles used have a pore volume of 0.4 ml / 100 g or more, and thus an oil absorption of at least 50 ml / 100 g, preferably 150 ml / 100 g. The above should be used. When the oil absorption is less than 50 ml / 100 g, as described above, when the heat sealing layer is melted, it is inferior in the ability to quickly adsorb a sufficient amount of the low melting point and low molecular weight components contained therein, and the effect of improving the heat resistance is sufficient. Cannot be achieved. The upper limit value of the oil absorption amount is not particularly important in the present invention. An oil absorption of 250 to 350 ml / 100 g or less possessed by wet silica produced by a wet method is sufficient, and it is not necessary to selectively use special wet silica having an oil absorption of more than that. Rather, the disadvantages of increasing costs are greater.

Hydrophobic wet silica particles can be produced in various sizes at the production stage, but in the application of the present invention, the average particle size is in the range of 2.0 to 7.0 μm. Things should be used.

When fine particles having an average particle size of less than 2.0 μm are used, it is generally impossible to obtain a good content adhesion preventing effect within a range of coating amount and adhesion amount that does not adversely affect heat sealability. On the other hand, when coarse particles exceeding 7.0 μm are used, not only the adhesion to the heat sealing layer (5) is deteriorated, but also the heat sealing property is hindered .

Further, the amount of deposition of the hydrophobic wet silica particles in the anti-adhesion layer (6) (coating amount) is set it to the range of 0.1 ~1.0g / ^{m 2.} When the adhesion amount of the hydrophobic wet silica particles is less than the above lower limit of 0.1 g / m ² , it is not possible to obtain a good content adhesion preventing effect. On the other hand, when the adhesion amount exceeds the above upper limit value of 1.0 g / m ² , the content adhesion preventing effect is saturated, while the adhesion preventing layer (6) inhibits the heat sealing property of the heat sealing layer (5). Specifically, the sealing strength (peeling resistance) is lowered by 20% or more as compared with the case where the adhesion preventing layer (6) is not provided, and there is a possibility that the stable and good sealing performance of the container is impaired. In addition, the adhesion with the heat sealing layer (5) is also lowered.

  In the production of the lid material according to the present invention, the method for forming the adhesion preventing layer (6) also affects the content adhesion preventing performance and heat sealability of the lid material.

  In the method for producing a lid according to the present invention, the adhesion preventing layer (6) is formed by first preparing a dispersion in which hydrophobic fine particles are dispersed at a predetermined concentration in an organic solvent, and using this dispersion as a heat sealing layer in the lid body. Apply to the outer surface of (5).

  As the solvent used for preparing the dispersion, an organic solvent is preferably used in order to ensure the fixability and adhesion of the hydrophobic fine particles to the underlying heat sealing layer (5). It is particularly preferable to use an organic solvent having a polar group. Of these, the use of alcohols is preferred, and ethanol and methanol are particularly preferred from the standpoints of cost, safety, water repellency and the like.

  The dispersion concentration of the fine particles in the dispersion can be arbitrarily set in consideration of the relationship with the coating amount of the hydrophobic fine particles. However, when the concentration is less than 2% (fine particles 2 g: solvent 100 mL), a sufficient amount of the hydrophobic fine particles is uniform. Application is difficult, and if the concentration is higher than 10%, the application amount tends to be excessive. A suitable dispersion concentration is about 3 to 6%.

  Any known method can be adopted as means for applying the dispersion. For example, a gravure coating method, spraying, a bar coating method, etc. can be arbitrarily adopted.

  Needless to say, the coating amount of the dispersion should correspond to the amount of the hydrophobic wet silica particles as described above in the adhesion preventing layer (5).

  Next, after the above coating process, the lid body is subjected to a drying process, the solvent in the coating dispersion is volatilized, and a predetermined amount of the hydrophobic wet silica particles are uniformly distributed to prevent adhesion. Layer (6) is formed. This drying may be performed by natural drying, but is preferably performed by forced heating to improve the working efficiency and the adhesion of the hydrophobic wet silica particles to the heat sealing layer (5). The heating conditions at this time are not particularly limited, but should be set to a temperature of 80 to 140 ° C., preferably 100 to 120 ° C., a time of 5 to 30 seconds, and preferably about 10 to 20 seconds. If the temperature is lower than the lower limit of 80 ° C., the drying process takes time, and if the time is less than 5 seconds, the drying becomes insufficient, and the adhesion preventing layer is likely to be partially peeled off or dropped during subsequent handling. On the other hand, it has been confirmed that when the drying temperature is set to a high temperature exceeding 140 ° C. or the time is set to a time exceeding 30 seconds, the surface hydrophobicity and water repellency of the hydrophobic wet silica particles are impaired. . The mechanism of the decrease in hydrophobicity has not yet been elucidated.

  Next, in order to confirm the effect of the present invention, various examples will be shown in comparison with comparative examples.

(Preparation of lid body)
A polyethylene terephthalate film having a thickness of 12 μm was used as the substrate film (2), and an aluminum foil (3) having a thickness of 30 μm was bonded to one surface thereof with a polyurethane-based dry laminate adhesive to obtain a substrate layer (1).

  Next, an intermediate resin layer (4) is formed by laminating and bonding a 20 μm thick polyethylene film to the surface of the base material layer (1) on the aluminum foil (3) side using the same adhesive as described above. A heat sealing layer (5) was formed on the outside by a gravure coating method. The laminate of the base material layer (1) / intermediate resin layer (4) / heat sealing layer (5) obtained in this way was used as the lid body.

Here, as the heat sealing layer (5), using the four kinds of hot melt adhesives below HM1～4, both the coating amount was 18 g / ^{m 2.}

HM1: Ethylene-vinyl acetate copolymer 55% by weight / wax 40% by weight / tackifier (rosin) 5% by weight
HM2: 46% by weight of ethylene-vinyl acetate copolymer / 43% by weight of wax / 11% by weight of tackifier (rosin)
HM3: 43% by weight of ethylene-vinyl acetate copolymer / 48% by weight of wax / 9% by weight of tackifier (rosin)
HM4: 30% by weight of ethylene-vinyl acetate copolymer / 35% by weight of wax / 35% by weight of tackifier (rosin)

(Coating of hydrophobic silica particles)
As hydrophobic silica particles, the following four kinds of hydrophobic wet silica particles A to D and the following hydrophobic dry silica particles E were prepared.
A: Hydrophobic wet silica average particle size 2.7 μm, oil absorption 240 ml / 100 g
(Product name: Silo Hovic 100)
B: Hydrophobic wet silica average particle diameter 3.9 μm, oil absorption 230 ml / 100 g
(Product name: Silo Hovic 200)
C: Hydrophobic wet silica average particle diameter 6.7 μm, oil absorption 50 ml / 100 g
(Product name: Silo Hovic 603)
D: Hydrophobic wet silica average particle size 8.0 μm, oil absorption 165 ml / 100 g
(Product name: Silo Hovic 4004)
E: Hydrophobic dry silica average particle size 0.1 μm or less (primary particle average particle size 7 nm)
(Product name: Aloe Gil R812S)

  Each of the hydrophobic silicas A to E was dispersed in an ethanol solvent at a dispersion concentration of 5% to prepare various dispersions.

  Next, these various dispersions were applied to the outer surface of the heat sealing layer (5) of the lid body by the gravure coating method under various application amounts shown in Tables 1 and 2. The coating amounts shown in Tables 1 and 2 indicate the weight ratio of the hydrophobic fine particles after drying.

(Dry)
Next, each sample coated with the above dispersion was forcibly dried under the drying conditions shown in Tables 1 and 2, and the content adhesion preventing layer (6) comprising the hydrophobic silica particles was formed on the heat sealing layer (5). Various sample Nos. Of Examples and Comparative Examples shown in Table 1 and Table 2 were formed. 1-23 were obtained.

(Evaluation test)
And the following evaluation test was done about each sample.
(1) Anti-adhesion performance Aloe yoghurt (Trademark “Morinaga Aloe Yoghurt” manufactured by Morinaga Milk Industry Co., Ltd.) was dropped on the back of the lid of each sample, that is, the outer surface of the anti-adhesion layer, as about 0.5 cc droplets. When the sample was slowly tilted, the “tilt angle when the droplet started to roll” was measured, and evaluated according to the following criteria.
◎ ・ ・ ・ 30 degrees or less ○ ・ ・ ・ 31 degrees or more and 60 degrees or less △ ・ ・ ・ 61 degrees or more and 90 degrees or less × ・ ・ ・ 90 degrees or more

(2) Sealing property The lid material of each sample was heat-sealed on the flange surface of the container body (paper / polyethylene container) under a hot-pressure sealing condition of 120 to 180 ° C. × 0.2 MPa × 1.0 sec.

Then, the seal strength (peeling resistance / sealing strength of the lid material) in the lid material as it is without the adhesion preventing layer was used as a reference value, and the rate of decrease in the seal strength was judged and evaluated according to the following criteria.
◎ ・ ・ ・ Approximately equivalent to those without adhesion prevention layer ○ ・ ・ ・ Strength reduction less than 10% △ ・ ・ ・ Strength reduction less than 10-20% × ・ ・ ・ Strength reduction over 20%

(3) Adhesiveness A weight (500 g) wrapped with a black cloth was placed vertically on the surface of the adhesion preventing layer of the lid material of each sample, and slowly rubbed by a length of 200 mm, and the silica adhering to the cloth was visually confirmed.

And the transfer adhesion amount (peeling amount) of the hydrophobic fine particles and the adhesion preventing layer in the black cloth was visually inspected and evaluated according to the following evaluation criteria.
◎ ・ ・ ・ Almost no adhesion ○ ・ ・ ・ Slight adhesion that is considered acceptable △ ・ ・ ・ Some adhesion × ・ ・ ・ Clearly much adhesion

(4) Heat resistance Each sample was heated at 100 ° C. for 1 minute in a heating furnace, and then the same test as the adhesion prevention performance test of the above (1) was performed and evaluated according to the same criteria.

  The results of the above evaluation tests (1) to (4) are shown together in Table 1.

  As shown in the test results of “adhesion prevention performance” in Tables 1 and 2, in the contents adhesion prevention lid material according to the present invention, the yogurt droplet starts rolling and moving only by slightly tilting the sample. This indicates that the contents containing viscous liquid components such as yogurt, pudding, and jelly are excellent in the effect of preventing the contents from adhering to the back surface of the lid. In addition, as shown in the results of the “sealability” test, the presence of the adhesion preventing layer hardly impairs the heat sealability, and the above adhesion prevention performance can be imparted while maintaining good sealing performance. In addition, as shown in the results of the “adhesion” test, the adhesion of the anti-adhesion layer made of hydrophobic particles is good, and there is a risk of unintentional separation and dropping of hydrophobic fine particles, partial peeling of the anti-adhesion layer, etc. In addition, the content adhesion prevention performance can be stably maintained over a long period of time, and there is no possibility of foreign matter entering the container. Furthermore, as shown in the test result of “heat resistance”, in the comparative example using the dry silica imparted with hydrophobicity, the original adhesion prevention performance is remarkably achieved only by receiving a heating history of only 100 ° C. × 1 minute. In the examples of the present invention using hydrophobic wet silica obtained by subjecting wet silica to hydrophobic processing, none or almost no adhesion prevention performance deteriorates even when subjected to the same heating history. Could be confirmed.

DESCRIPTION OF SYMBOLS 1 ... Base material layer 2 ... Base film layer 3 ... Metal foil layer 4 ... Intermediate resin layer 5 ... Heat sealing layer 6 ... Adhesion prevention layer

Claims (5)

Having at least a base material layer and a heat sealing layer,
In the cover material comprising the hot-sealing adhesive, the heat sealing layer contains a wax and an ethylene-unsaturated ester polymer as main components, and contains 30% by weight or more of the ethylene-unsaturated ester polymer .
An adhesion preventing layer on the outer surface of the heat sealing layer;
Said adhesion prevention layer, Ri Do hydrophobic wet silica particles having an average particle size of 2.0~7.0μm imparted with hydrophobic wet silica particles, and the amount of deposition of the hydrophobic wet silica particles in said adhesion prevention layer the contents of adhesion preventing cover member, wherein 0.1 to 1.0 g / ^{m 2} der Rukoto by weight after drying. The content adhesion prevention cover material according to claim 1, wherein the hydrophobic wet silica particles have an oil absorption of 50 ml / 100 g or more. The content adhesion prevention cover material according to claim 1 or 2, wherein the content of the ethylene-unsaturated ester copolymer in the heat sealing layer is 40 parts by weight or more. It has at least a base material layer and a heat sealing layer, and the heat sealing layer contains a wax and an ethylene-unsaturated ester polymer as main components, and contains 30% by weight or more of the ethylene-unsaturated ester polymer. Prepared by dispersing hydrophobic wet silica particles having an average particle size of 2.0 to 7.0 μm, which is obtained by imparting hydrophobicity to wet silica particles, in an organic solvent on the outer surface of the heat sealing layer of the cover material made of hot melt adhesive. The amount of the wet silica particles adhered is 0.1 to 1.0 g / m by weight after drying. ² A method for producing an anti-adhesion cover material, wherein the anti-adhesion layer is formed by drying under dry conditions of a temperature of 80 to 140 ° C. and a time of 5 to 30 seconds. The manufacturing method of the content adhesion prevention lid | cover material of Claim 4 whose temperature in the drying conditions after application | coating of the said dispersion liquid is 100-120 degreeC, and time is 10 to 20 seconds.

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