JP5520145B2 - Contents adhesion prevention lid material and manufacturing method thereof - Google Patents

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 when opened, resulting in waste due to the loss of the contents, or time and effort to peel off the contents, and an unclean feeling. 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.

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

  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. The adhesion prevention layer is formed by using a very fine oxide fine particle having an average primary particle diameter of 3 to 100 nm and a coating liquid in which the fine particle is dispersed in a dispersion medium such as ethanol in a gravure coating method or a bar coating method. was coated with a coating means, followed by drying, the amount of deposition of the fine particles after drying 0.01 to 10 g / ^{m 2,} preferably from 0.2 to 1.5 g / ^{m 2,} optimally 0. The porous layer has a thickness of 3 to 1 g / m ² and a thickness of 0.1 to 0.5 μm, preferably 0.2 to 2.5 μm.

  This prior proposal technique can have a very excellent effect in terms of the content adhesion preventing effect.

  On the other hand, in the heat seal portion of the lid material with respect to the container body, the porous layer made of inorganic fine particles becomes a contaminant and inhibits heat sealability. For this reason, the sealing strength is generally lowered, and it is difficult to maintain good sealing properties and required peel strength.

  As one means for wiping out such difficulties, it is considered that the sealing strength of the heat-sealing layer itself is designed to be high in terms of its composition to compensate for the decrease in sealing strength due to the inclusion of the hydrophobic fine particle layer. Is done. However, according to such means, due to the variation in the amount of hydrophobic fine particles that often occurs during coating, the seal strength becomes too large particularly in a portion where the amount of application is small, and the easy peelability is impaired. There is a great risk of being caught.

  On the other hand, it is naturally considered that the decrease in the seal strength is suppressed by reducing the coating amount. However, in this case, since a dispersion liquid having a low dispersion concentration of hydrophobic fine particles is used, it is difficult to uniformly apply the fine particle distribution after drying, and as a result, the content adhesion preventing effect varies. It is difficult to obtain a stable and uniform sealing strength and peel resistance on the entire circumference, and there is a risk that the contents may inadvertently leak from a weak seal strength part. When trying to open the material by pulling it strongly, there is a problem that the contents may scatter.

  In view of the above-described problems in the prior art, the present invention is intended to make further improvements thereof, specifically, while maintaining stable and good heat sealing performance, it is excellent in content adhesion prevention performance. And it aims at providing the new improvement technique which can improve the stable adhesiveness with respect to the heat sealing layer of the hydrophobic fine particle which expresses this adhesion prevention effect, and can ensure the stability persistence of the said content adhesion prevention effect.

  In order to achieve the above object, the present invention first presents the following means [1] to [9] for a method for producing a content adhesion preventing lid.

  [1] A hydrophobic fine particle layer dried by applying a dispersion liquid in which hydrophobic fine particles are dispersed in an organic solvent on the outer surface of the heat sealing layer of a cover material having at least a base material layer and a heat sealing layer, and drying The content adhesion preventing lid material is characterized in that at least free fine particles are removed by wiping the surface of the material with a wiping member, and a thin anti-adhesion layer having a uniform distribution of the fine particles is formed on the heat sealing layer by the remaining fine particles. Production method.

[2] The method for producing a content adhesion preventing lid material according to [1], wherein an application amount in the application step of the dispersion liquid is set to 0.4 g / m ² or more in a weight after drying of the hydrophobic fine particles.

[3] The anti-adhesion layer controls the residual adhesion amount of the hydrophobic fine particles by wiping in the range of 0.05 to 0.3 g / m ^2. The content prevention according to [1] or [2] A method for manufacturing a lid.

[4] The method for producing a content adhesion preventing lid material according to the above [3], wherein the residual adhesion amount of the hydrophobic fine particles by wiping is controlled in a range of 0.1 to 0.2 g / m ² .

  [5] The method for producing a content adhesion preventing lid material according to any one of [1] to [4], wherein a non-woven fabric or a pile fabric is used as the wiping member.

  [6] The method for manufacturing a content adhesion preventing lid material according to any one of [1] to [5], wherein the wiping step is performed by impregnating a wiping member with an organic solvent.

  [7] The method for producing a content adhesion preventing lid material according to any one of [1] to [6], wherein the hydrophobic fine particles have an average particle diameter of 1 nm to 5,000 nm.

  [8] The method for producing a content adhesion preventing lid material according to any one of [1] to [7], wherein the hydrophobic fine particles are hydrophobic silica.

  [9] The content according to any one of [1] to [8], wherein the heat sealing layer is formed of a hot melt resin composition containing a wax and an ethylene-unsaturated ester copolymer as main components. A method for manufacturing an anti-adhesion lid.

  The present invention also presents means of the following items [10] to [15] for the configuration of the content adhesion preventing lid material.

[10] In a lid having at least a base material layer and a heat sealing layer,
An adhesion preventing layer on the outer surface of the heat sealing layer;
The anti-adhesion layer is composed of hydrophobic fine particles, and the adhering amount is set in a range of 0.05 to 0.3 g / m ² .

[11] The content adhesion preventing lid material according to [10], wherein the adhesion amount of the hydrophobic fine particles is set in a range of 0.1 to 0.2 g / m ² .

  [12] The content adhesion preventing lid material according to [10] or [11], wherein the adhesion preventing layer is formed by the method according to any one of [1] to [9]. .

  [13] The content adhesion preventing lid material according to any one of [10] to [12], wherein the hydrophobic fine particles have an average particle diameter of 1 nm to 5,000 nm.

  [14] The content adhesion preventing lid material according to any one of [10] to [13], wherein the hydrophobic fine particles are hydrophobic silica.

  [15] The content according to any one of [10] to [14], wherein the heat sealing layer is composed of a hot melt resin composition containing wax and an ethylene-unsaturated ester copolymer as main components. Adhesion prevention lid.

  In the production method according to item [1], the present invention applies a sufficient amount of hydrophobic fine particles by weight after drying to the outer surface of the heat sealing layer, and removes free fine particles by wiping after drying. Since the desired amount of hydrophobic fine particles are left as adhering residual fine particles to form the expected anti-adhesion layer, the remaining amount of hydrophobic fine particles forming the anti-adhesion layer can be arbitrarily controlled, The remaining adhesion amount of the hydrophobic fine particles can be greatly reduced within a range in which the required content adhesion preventing effect can be ensured. At the same time, it is easy to make the distribution uniform. Accordingly, despite the inclusion of the hydrophobic fine particle layer as a contaminant in the heat seal portion, the heat seal performance is not greatly hindered, and the seal strength and sealability can be maintained well. Can be made uniform over the entire circumference, and as a result, it is possible to improve the stable peelability for opening. On the other hand, the anti-adhesion layer is composed of a small amount of hydrophobic fine particles, but as is apparent from the comparison of the examples and comparative examples described later, it is simply formed by coating and drying. In this case, since the hydrophobic fine particles are uniformly distributed over the entire surface without causing uneven coating, a necessary and sufficient content adhesion preventing effect can be expressed on the entire surface. Moreover, since the hydrophobic fine particles forming the adhesion preventing layer are adhering particles that remain without being removed by wiping, unintentional fine particles are dropped or peeled off during handling and use of the lid, or external interference. It is possible to prevent generation of whitening marks due to friction with an object, and to maintain a stable content adhesion preventing effect over a long period of time and maintain an inferior appearance.

Further, in the method described in the above item [2], the amount of coating in the coating step of the dispersion is set to 0.4 g / m ² or more in terms of the weight after drying, so that it is surely required even by wiping after drying. Thus, it is possible to form an adhesion preventing layer having a small variation in the total remaining adhesion amount, that is, a uniform distribution of fine particles.

Further, as described in the above item [3], the residual adhesion amount is controlled to be in the range of 0.05 to 0.3 g / m ² , so that the seal strength is reduced as compared with the cover material having no adhesion preventing layer. Therefore, it is possible to achieve a necessary and sufficient content adhesion preventing effect while suppressing the content to 10% or less.

Furthermore, as described in the above item [4], the effect of the item [3] can be improved more reliably and reliably by controlling the residual adhesion amount in the range of 0.1 to 0.2 g / m ^2. Can be achieved.

  In addition, as described in [5] above, by using a nonwoven fabric or a pile fabric as a wiping member, an operation of wiping off excessive fine particles including free fine particles from a dry coating layer of hydrophobic fine particles can be easily performed. In addition, the removed hydrophobic fine particles can be captured and held between the fibers, which is advantageous without significantly degrading the working environment.

  Further, as described in the above item [6], by wiping in a state where the wiping member is impregnated with an organic solvent, the wiping work efficiency can be further improved and the fine particles removed by wiping can be removed. This can also improve the holding action.

  In addition, as described in the item [7], by using hydrophobic fine particles having an average particle diameter of 1 nm to 5,000 nm, a relatively inexpensive material that is easily available from the market is used. A lid material excellent in the adhesion preventing effect can be produced.

  Furthermore, as described in the above item [8], when the hydrophobic silica is selectively used for the hydrophobic fine particles, it has an excellent content adhesion preventing effect with a relatively inexpensive material that is easily available from the market. A lid can be obtained.

  In addition, as described in the above item [9], when the heat sealing layer is composed of a hot melt resin composition containing a wax and an ethylenically-unsaturated steal copolymer as main components, the above [1] to [ The effect of the method described in the item [8] can be achieved reliably.

In addition, in the lid material having the configuration described in the above item [10], the formation of an adhesion preventing layer with hydrophobic particles having a very small amount and a uniform distribution causes little reduction in seal strength, and the content of It is possible to provide a lid material in which both requests that the adhesion preventing effect is good are harmonized in a balanced manner at the same time.

  Moreover, when it is set as the structure as described in said [11] term, the effect of said [10] term can be achieved more favorably and reliably.

  In the configuration described in [12], the lid material having the excellent effect described in [10] and [11] can be easily and reliably obtained by an easy manufacturing method.

  In the configuration described in [13], a relatively inexpensive hydrophobic fine particle material that is easily available from the market can be used to provide an excellent content adhesion preventing effect.

  In addition, as described in the above item [14], when the hydrophobic fine particles are selectively used with hydrophobic silica, an inexpensive material easily available from the market is often used, and the content adhesion preventing effect is excellent. be able to.

  Furthermore, as described in the above item [15], by applying the configuration described in the items [10] to [14] to a lid member having a heat sealing layer made of a hot melt resin composition, The effects of the items [10] to [14] can be achieved better and reliably.

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. 2 is a cross-sectional view schematically showing the coated fine particle layer when the dispersion of hydrophobic fine particles is applied and then dried. FIG. 3 is a cross-sectional view schematically showing the form of an anti-adhesion layer formed by residual fine particles after removing excessive fine particles including free fine particles by wiping the surface of the hydrophobic fine particle layer after drying with a wiping member. is there.

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

  The base film layer (2) is disposed 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 resin layer (4) and the container side. For example, besides a hot melt adhesive, a lacquer type adhesive or a known sealant film can also be used. In particular, a hot melt adhesive is generally used for a lid for a container for yogurt packaging, and includes a wax and an ethylene-unsaturated ester copolymer as main components, and the ethylene-unsaturated material. It is preferable to use a hot melt resin composition containing a saturated ester copolymer in a proportion of 30% by weight or more. The reason is that in the formation of the adhesion preventing layer by the method described later, the adhesion stability of the hydrophobic fine particles can be made good, and the adhesion of the adhesion preventing layer (6) to the heat sealing layer (5) is good. By what can be done. 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, as shown in FIG. 3, the anti-adhesion layer (6) constituting the main component of the present invention is composed of a layer having a porous structure in which hydrophobic fine particles (10) are overlapped, and a heat sealing layer (5 ) Side, a part of the fine particles (10) are attached to the heat sealing layer (5) in a state of being embedded in or in contact with the heat sealing layer (5). The adhesion preventing layer (6) is extremely thin in thickness and has a uniform fine particle distribution. Specifically, the adhesion amount (coating amount ) of the hydrophobic fine particles (10) in the adhesion preventing layer (6 ) is 0 . Range 05~0.30g / ^{m 2,} in which preferably is set in a range of 0.1 to 0.2 g / ^{m 2.} When the range of the adhesion amount of the hydrophobic fine particles (10) is less than the above lower limit of 0.05 g / m ² , it is not possible to obtain a good content adhesion preventing effect. On the contrary, when the upper limit of 0.30 g / m ² is exceeded, although the content adhesion preventing effect is excellent, the adhesion preventing layer (6) inhibits the heat sealability of the heat sealing layer (5), specifically, Compared to the case where the adhesion preventing layer (6) is not provided, the sealing strength (peeling strength) is lowered by 20% or more, and there is a possibility that the sealing property of a stable and good container is impaired.

  The hydrophobic fine particles constituting the adhesion preventing layer (6) play a dominant role in the content adhesion preventing performance of the lid, and are made of a hydrophobic substance having a surface energy of 20 mN / m or more. If there is, the material is not particularly limited. Specific examples include hydrophobic silica, alumina, calcium oxide, calcium carbonate, calcium sulfate, calcium silicate, and the like. Of these, the use of hydrophobic silica or alumina is preferred from the viewpoint of hydrophobic performance, cost, availability of ultrafine particle materials from the market, and the like.

  The average particle diameter of primary particles of hydrophobic fine particles should be in the range of 1 to 5,000 nm. Ultrafine particles having an average particle size of less than 1 nm are difficult to obtain from the market and are disadvantageous in terms of cost. On the other hand, if the average particle size exceeds 5,000 nm, the risk of hindering heat sealability increases, and the adhesion preventing effect may be reduced, which is not suitable. A preferred average diameter is in the range of 3 to 3000 nm, particularly preferably 3 to 1000 nm.

  In the production of the lid according to the present invention, the method for forming the adhesion preventing layer (6) also has a significant influence on the contents adhesion preventing performance and heat sealability of the lid.

  In the method for producing a lid according to the present invention, the adhesion preventing layer (6) is formed by applying an excessive amount of hydrophobic fine particles (10) to the outer surface of the heat sealing layer (5), drying, and wiping member. It is performed by wiping and removing excess hydrophobic fine particles by the above, and sequentially performing each step of finish drying as necessary.

  Next, details of each of these steps will be described.

[Coating of hydrophobic fine particles]
First, a dispersion in which hydrophobic fine particles are dispersed in a predetermined concentration in an organic solvent is prepared, and this is applied to the outer surface of the heat sealing layer (5) in the lid body.

  The solvent used for the preparation of the dispersion should be an organic solvent in order to ensure the fixability and adhesion of the hydrophobic fine particles to the underlying heat-sealing layer (5). In particular, an organic solvent having a polar group is used. Is preferred. 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.

What is important here is a substantial coating amount of the dispersion. That is, a sufficient amount should be applied so that the weight after drying of the hydrophobic fine particles after application is 0.4 g / m ² or more. When the coating amount is such that the weight after drying is less than 0.4 g / m ² , it may be difficult to keep the remaining amount of hydrophobic fine particles adhered in the subsequent wiping step within a predetermined range defined by the present invention. That said, excessive amounts of application exceeding ² g / m ² are useless. Rather, the material is wasted and the economic loss is greater. A preferable coating amount is approximately in the range of 0.5 to 1.0 g / m ² in terms of the weight after drying of the hydrophobic fine particles.

[Dry]
After the above coating process, the lid body is subjected to a drying process to volatilize the organic solvent in the dispersion to form a coated fine particle layer (6a) in which the dried hydrophobic fine particles (10) are relatively thick. Yes (see FIG. 2), this drying may be carried out by natural drying, but it is desirable to carry out forced heating drying in order to improve working efficiency and fixability of the hydrophobic fine particles (10). The heating conditions at this time are not particularly limited, but should be set to a temperature of 60 to 140 ° C., preferably 80 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 60 ° C., the drying process takes time, and if the time is less than 5 seconds, the drying is insufficient, and the adhesion preventing layer is likely to be partially peeled off or dropped during subsequent handling. On the other hand, when the drying temperature is set to a high temperature exceeding 140 ° C., or the time is set to a time exceeding 30 seconds, especially when hydrophobic silica is used for the hydrophobic fine particles, the hydrophobicity and repellent property of the hydrophobic fine particles. There is a risk that the aqueous properties may be impaired.

  As shown schematically in FIG. 2, the coated fine particle layer (6a) that has been dried after coating has a relatively large amount of hydrophobic fine particles having a porous structure on the heat sealing layer (5). Part of the fine particles (10a) located in the lower layer portion on the heat sealing layer side are bitten into the heat sealing layer (5) or brought into contact with each other. The fixing fine particles (10a) adhered to and integrated with the sealing layer (5) are formed, and the fine particle group (10b) existing in the other upper layer portion is entangled directly or indirectly with the fixing fine particles (10a). It exists as free fine particles (10b) stable at a fixed position.

[Wipe off]
Next, as schematically shown in FIG. 2, the surface of the coated fine particle layer (6a) is wiped by lightly wiping with a wiping member (11), thereby including at least the free fine particles (10b). Excess fine particles are removed, and the remaining fine particles containing the fixing fine particles (10a) form a thin porous structure anti-adhesion layer (6) in which the fine particles overlap as shown in FIG.

In particular, in this wiping operation, the remaining adhesion amount of the hydrophobic fine particles in the adhesion preventing layer (6) after wiping is 0.05 to 0.3 g / m ² , more preferably 0.1 to 0.2 g / m ^2. It is important to control the amount of wiping so that it falls within the range. The fine particle distribution in the adhesion preventing layer (6) is made uniform by wiping and does not require any special operation, but the adhesion amount range deviates from the range of 0.05 to 0.3 g / m ^2. As described above, sufficient satisfaction cannot be obtained simultaneously with respect to both the content adhesion preventing effect and the seal strength.

  The material of the wiping member used for wiping is not particularly limited, but is a cotton-like non-woven fabric composed of fibers that are flexible and elastic and have a relatively small fineness, and a pile fabric having a high-density fiber pile layer on the surface. Alternatively, it is preferable to use absorbent cotton or the like. By using these fiber wipers, it is easy to make the remaining adhesion amount of the hydrophobic fine particles uniform over the entire surface. In addition, the removed hydrophobic fine particles can be captured and held between the fibers, thereby contributing to prevention of contamination of the surrounding work environment. Of course, the material is not limited to the above materials, and ordinary woven fabrics, synthetic resin foams, rubber foams, and the like can also be used.

  The wiping operation can be performed manually using a manual wiping tool equipped with the wiping member (11). However, industrially, a wiping roller equipped with a wiping member is prepared. In the process of transferring the sheet-like lid material main body to be wiped, the roller can be brought into contact at a predetermined contact pressure and a rubbing speed. Regardless of which method is used, the wiping amount of the hydrophobic fine particles can be adjusted by adjusting the pressing pressure (contact pressure), rubbing speed, rubbing frequency, etc. of the wiping member.

  In the wiping, it is preferable that the wiping member (11) is soaked and impregnated with a solvent, particularly an organic solvent having a polar group such as ethanol or methanol. By using the wiping member impregnated with the solvent, the wiping work efficiency, that is, the removal efficiency of the hydrophobic fine particles can be further improved, and the removal and capturing effect of the removed fine particles can be further improved.

[Finish drying]
Drying after wiping is not an essential step, but is performed as necessary.

  In particular, when performing wiping by impregnating the wiping member with a solvent, it is preferable to perform forced drying immediately in terms of work efficiency. The preferable drying temperature and time in this case are the same as those in the above-described drying step.

  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), a hot melt having a composition comprising wax: 40 parts by weight, ethylene-vinyl acetate copolymer: 54 parts by weight, rosin: 5 parts by weight, and silicon oil: 1 part by weight. The resin composition was used, and a hot melt type was applied by a gravure coating method at a coating amount of 18 g / m ² .

(Coating of hydrophobic fine particles)
The following two types A and B were prepared as hydrophobic fine particles.

A: Hydrophobic silica Primary particle average particle diameter 7 nm
(Product name: Aloe Gil R812S)
B: Hydrophobic silica average particle diameter 3000 nm
(Product name: Silo Hovic 100)

  Then, each of the hydrophobic silicas A and B was dispersed in the organic solvents such as ethanol solvent and methanol solvent at the dispersion concentrations shown in Table 1 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 Table 1. The coating amounts shown in Table 1 are all indicated by the weight of the hydrophobic fine particles after drying.

(Primary drying)
Next, each sample coated with the above dispersion was forcibly dried under the drying conditions shown in Table 1, and the dried coating fine particle layer (6a) having an excessive adhesion amount as shown in FIG. 2 on the heat sealing layer (5). ) Was formed.

(Wipe off)
Next, for the samples 6 and 12 of the examples and comparative examples of the present invention, the surface of the dried coated fine particle layer (6a) was lightly pressed against the surface with the wiping member (11) and slid once to several times. By rubbing, the excess fine particles in the vicinity of the surface side including the free fine particles are wiped off, and various residual adhesion amounts on the heat-sealing layer (5) by the remaining adhered fine particles are shown in FIG. Such a content adhesion preventing layer (6) was formed.

As the wiping member (11), a cotton-like non-woven fabric (polyester non-woven fabric having a fineness of 2 denier and a basis weight of 200 g / m ² ) was used, and wiping was performed in a state in which ethanol or methanol as an organic solvent was soaked. .

  In Comparative Examples 7 to 9 and 13 which should be compared with the examples of the present invention, the wiping off was not performed and the hydrophobic fine particle layer after coating and drying was used as it was as a content adhesion preventing layer.

  The amount of fine particles remaining after wiping was measured using a 10 cm × 10 cm sample piece cut out from the cover material on which the adhesion preventing layer (6) was formed, and the surface on the adhesion preventing layer (6) side was measured. Wipe until the water repellency disappears with absorbent cotton soaked with alcohol, and it is obtained from the weight difference between the sample pieces before and after that.

(Finish drying)
In each of the samples of Examples and Comparative Examples 6 and 12 of the present invention, the wiping was performed using the wiping member impregnated with the organic solvent as described above, so that the content adhesion preventing layer (6 ) Was in a state where the surface was slightly wet with a solvent. Therefore, these products were subjected to forced heating drying under the finish drying conditions shown in Table 1.

  Thus, various samples of Examples and Comparative Examples shown in Table 1 were obtained. And the following evaluation test was done about each sample. The results are also shown in FIG.

(Evaluation test)
(1) Anti-adhesion performance Each sample No. Aloe yogurt (Trademark “Morinaga Aloe Yogurt” manufactured by Morinaga Milk Industry Co., Ltd.) is dropped on the back of the lid material 1-15, that is, on the outer surface of the anti-adhesion layer, and the sample is slowly tilted. When the above-mentioned droplet was measured, the “inclination angle when it 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) Sealability Sample No. 1 to 15 of the container body (paper / polyethylene container, but for the cover material of sample No. 15, polystyrene container) under the hot-pressure sealing condition of 120 to 180 ° C. × 0.2 MPa × 1.0 sec. Heat sealed on the flange surface.

  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.

◎ ... Almost the same as the one without adhesion prevention layer ○ ... Less than 20% strength reduction ×… More than 20% strength reduction

(3) Adhesion Sample No. A weight (500 g) wrapped with a black cloth was placed vertically on the surface of the adhesion preventing layer of each of the lid materials 1 to 15 and slowly rubbed by a length of 200 mm, and the silica adhered 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.

◎ ・ ・ ・ No adhesion ○ ・ ・ ・ Slight adhesion as permissible range △ ・ ・ ・ Clear adhesion × ・ ・ ・ Many adhesion

  The results of the above evaluation tests (1) to (3) are shown together in Table 1.

  As shown in the results of the “adhesion prevention performance” test in Table 1, in the content 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.

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 (10)

  A dispersion liquid in which hydrophobic fine particles are dispersed in an organic solvent is applied to the outer surface of the heat sealing layer of the lid member having at least a base material layer and a heat sealing layer, and after drying, the surface of the dried hydrophobic fine particle layer is applied. A method for producing a content adhesion preventing lid material, characterized in that at least free fine particles are removed by wiping with a wiping member, and a thin anti-adhesion layer having a uniform distribution of fine particles is formed on the heat sealing layer with residual fine particles. The manufacturing method of the content adhesion prevention lid | cover material of Claim 1 which sets the application quantity in the application | coating process of the said dispersion liquid to 0.4 g / m < ² > or more in the weight after drying of hydrophobic fine particles. The said adhesion prevention layer is a manufacturing method of the content adhesion prevention lid | cover material of Claim 1 or 2 which controls the residual adhesion amount of the hydrophobic fine particle by wiping in the range of 0.05-0.3 g / m < ² >. The manufacturing method of the content adhesion prevention cover material of Claim 3 which controls the residual adhesion amount of the hydrophobic fine particle by wiping in the range of 0.1-0.2 g / m < ² >.   The manufacturing method of the content adhesion prevention lid | cover material of any one of Claims 1-4 which uses a nonwoven fabric or a pile fabric as the said wiping member.   The said wiping process is a manufacturing method of the content adhesion prevention lid | cover material of any one of Claims 1-5 performed by making a wiping member impregnate an organic solvent.   The method for producing a content adhesion preventing lid material according to any one of claims 1 to 6, wherein the hydrophobic fine particles have an average particle diameter of 1 nm to 5,000 nm.   The method for producing a content adhesion preventing lid material according to any one of claims 1 to 7, wherein the hydrophobic fine particles are hydrophobic silica.   The said heat sealing layer consists of a hot-melt resin composition which contains a wax and an ethylene-unsaturated ester copolymer as a main component, The manufacture of the content adhesion prevention lid | cover material of any one of Claims 1-8. Method. The content adhesion prevention lid | cover material manufactured by the method of any one of the said Claims 1-9.

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