JP5670690B2 - 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 top 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. It has been.

  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. These prior arts are further improved in the content adhesion preventing effect as compared with the prior arts of Patent Documents 1 to 3, but they are 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.

  Further, the prior art disclosed in Patent Document 6 is to form a porous layer having a three-dimensional network structure with very fine oxide particles such as hydrophobic silica on the outer surface of the heat sealing layer.

  Although this prior proposed technique has a very excellent effect in preventing the adhesion of contents, the porous layer made of inorganic fine particles becomes a contaminant in the heat seal portion, and therefore, a stable and uniform sealing around the entire circumference. When it is difficult to obtain adhesive strength and peel strength, there is a risk that the contents may inadvertently leak from a weak seal strength part, or conversely, when you try to open the lid by strongly pulling the part with a strong seal strength part. However, there is a problem that the contents may be scattered, and further improvement is desired.

  In view of the problems as described above in the prior art, the present invention is intended to further improve them, specifically, while maintaining stable and good heat seal performance, it is excellent in content adhesion prevention performance, In addition, a new improvement technology that can improve the stability and persistence of the content adhesion preventing effect by enhancing the adhesion between the hydrophobic fine particles expressing the adhesion preventing effect and the adhesion between the lid material and the container. The purpose is to provide.

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

[1] 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 adhesion preventing layer is composed of a mixed composition of thermoplastic resin fine particles and hydrophobic inorganic fine particles having adhesion to the surface layer of the container body, and the thermoplastic resin fine particles and the hydrophobic inorganic fine particles have a polar group. A lid for preventing content adhesion, which is formed by applying and drying a coating liquid prepared by dispersing in a liquid dispersion medium .

  [2] The content adhesion preventing lid material according to [1], wherein the thermoplastic resin fine particles are made of an olefin resin or a resin composition containing an olefin resin as a main component.

  [3] The content adhesion preventing lid material according to [2], wherein the olefin-based resin is polyethylene, polypropylene, or an ethylene-unsaturated ester copolymer.

  [4] In the above [3], the ethylene-unsaturated ester copolymer is an ethylene-vinyl acetate copolymer, a vinyl acetate-vinyl chloride copolymer, or a vinyl acetate-vinyl chloride-maleic acid copolymer. The cover for preventing the contents from being attached.

  [5] The content adhesion preventing lid material according to any one of [1] to [4], wherein the thermoplastic resin fine particles have an average particle diameter of 1 nm to 5,000 nm.

[6] The content adhesion preventing lid material according to any one of [1] to [5], wherein the hydrophobic inorganic fine particles are hydrophobic silica.

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

[8] blending ratio of the thermoplastic resin particles and hydrophobic inorganic fine particles in the mixed composition is from 10 to 90 wt% thermoplastic resin fine particles in the solid content ratio is 90 to 10 wt% hydrophobic inorganic fine particles wherein The content adhesion preventing lid material according to any one of [1] to [7].

[9] The content adhesion preventing lid material according to any one of [1] to [8], wherein the mixed composition contains relatively more hydrophobic inorganic fine particles than the thermoplastic resin fine particles.

The present invention also presents the means of the following items [10] to [12] characterized by the adjustment of the coating liquid, the selection of the dispersion medium, the drying conditions of the coating film, etc. To do.

[10] on the outer surface of the heat sealing layer of the lid having at least a substrate layer and the heat sealing layer, thermoplastic resin fine particles and hydrophobic inorganic fine particles and a polar group having adhesion to the surface layer of the container body After coating the coating liquid prepared by dispersing in a liquid dispersion medium having a weight of 0.1 to 5.0 g / m ² after drying, the temperature is 80 to 140 ° C. and the time is 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.

[11] The method for producing a content adhesion preventing lid material according to [10] , wherein the dispersion medium is alcohol .

[12] The method for producing a content adhesion preventing lid material according to [11] , wherein the dispersion medium is methanol or ethanol .

According to the present invention, in the configuration of the above item [1], the hydrophobic inorganic fine particles are blended in the content adhesion preventing layer provided in addition to the outer surface of the heat sealing layer, so that the desired ratio corresponding to the blending ratio is obtained. In addition to being able to express the necessary and sufficient content adhesion preventing effect, the adhesion preventing layer also contains thermoplastic resin fine particles having adhesion to the surface layer of the container body . As a result, the binding strength between the primary and secondary particles of hydrophobic inorganic fine particles that are inherently poor in binding properties is compensated for, and at the same time, their adhesion to the heat-sealing layer is also improved, and unintentional particle dropping off is achieved. Further, it is possible to prevent the adhesion preventing layer from peeling off and maintain a stable content adhesion preventing effect over a long period of time. In particular, as described in the above item [1], by using a liquid dispersion medium having a polar group for the adjustment of the coating liquid, there is little possibility of reducing the surface energy of the hydrophobic inorganic fine particles. An anti-adhesion layer having good anti-adhesion performance can be formed. In addition, the inclusion of the above-mentioned thermoplastic resin fine particles in the anti-adhesion layer acts to supplement the heat sealability of the heat seal layer, and it is good and stable against the container body of the lid regardless of the presence of hydrophobic inorganic fine particle groups. Therefore, it is possible to ensure a suitable heat sealing property, that is, a suitable sealing property in which easy opening and sealing properties are harmonized.

  In addition, as described in the item [2], when the thermoplastic resin fine particles are fine particles made of an olefin resin or a resin composition containing an olefin resin as a main component, Appropriate heat sealability can be ensured.

  In particular, when the thermoplastic resin fine particles specifically listed in the items [3] and [4] are used, the most common heat in which the heat sealing layer is composed of hot melt. In the case of the seal lid member, the function and effect of the configuration of the above item [1] can be achieved even better.

  Furthermore, by using the thermoplastic resin fine particles having the average particle diameter as described in the above item [5], excellent openability and sealability can be achieved without impairing the content adhesion preventing effect.

Furthermore, as described in the above item [6], when hydrophobic silica is selectively used for the hydrophobic inorganic fine particles, an excellent content adhesion preventing effect is obtained with a relatively inexpensive material that is easily available from the market. Can be achieved.

Further, by using hydrophobic inorganic fine particles having an average particle diameter as described in the above item [7], the above-described content adhesion preventing effect can be obtained using a relatively inexpensive material that is easily available from the market. It can be realized reliably.

Further, in the configuration described in the above item [8], the lid material is selected by appropriately selecting the blending ratio of the thermoplastic resin fine particles and the hydrophobic inorganic fine particles according to the kind of the food packaged in the container. Thus, it is possible to impart an appropriate anti-adhesion performance required for the above.

In addition, as described in the above item [9], by providing a relatively large amount of the hydrophobic inorganic fine particles relative to the thermoplastic resin fine particles, it is possible to always provide a good content adhesion preventing performance to the adhesion preventing layer. Can do.

  Moreover, according to the manufacturing method of the content adhesion prevention cover material as described in said [10] item, the cover material which shows the effect by said [1] item can be obtained. In particular, when the coating amount and drying conditions of the coating layer of the coating liquid deviate from the specific range, a good content adhesion preventing effect cannot be exhibited. Alternatively, the productivity of the lid member is lowered and the production cost is increased.

Further, when the alcohol dispersion medium is used as described in the above item [11] , the corresponding effect in the item [10] can be obtained more reliably.

Furthermore, as described in the above item [12] , when a methanol or ethanol dispersion medium is used, the corresponding effect of the item [10] can be achieved more 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. 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 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, a hot melt adhesive, a lacquer type adhesive, or a known sealant film can be used. In particular, for a lid for a yogurt packaging container, it is common and preferable to use a hot melt adhesive. The thickness of the heat-sealing layer is not particularly limited, but is generally about 3 to 100 μm in thickness, preferably 10 to 50 μm from the viewpoint of cost, sealing performance, productivity, and the like. It is better to be in the range.

By the way, the adhesion preventing layer (6) constituting the main component of the present invention is composed of a mixed composition of thermoplastic resin fine particles having adhesion to the surface layer of the container body and hydrophobic inorganic fine particles. .

  The material of the thermoplastic resin fine particle is not particularly limited, but the thermoplastic resin has good compatibility with the heat sealing layer (5) and the hydrophobic fine particle, and a thermoplastic resin having good adhesion to the surface layer of the container body. It is desirable to select and use at least the thermoplastic resin as a main component. Examples of such thermoplastic resins include homopolymers such as vinyl acetate resins, polyolefin resins, polyester resins, acrylic resins, styrene resins, or two or more types of copolymers. Since it is a thermoplastic resin, the use of waxes having a low molecular weight, which has been conventionally used as an anti-adhesion agent for lids, is excluded. As a particularly preferable type of thermoplastic resin, the most preferable result can be obtained by using a thermoplastic resin containing at least one or more olefinic resins as a main component.

  More specifically, specific examples of the olefin resin include polyethylene, polypropylene, and an ethylene-unsaturated ester copolymer. Examples of the ethylene-unsaturated ester copolymer include an ethylene-vinyl acetate copolymer, a vinyl acetate-vinyl chloride copolymer, and a vinyl acetate-vinyl chloride-maleic acid copolymer.

  The thermoplastic resin is used in a state of being pulverized into fine particles. The average particle diameter of the thermoplastic resin fine particles is preferably 1 nm to 5000 nm. If the thickness is larger than 5000 nm, it tends to fall off from the heat sealing layer, which is not preferable. If it is smaller than 1 nm, there arises a problem that it is difficult to obtain industrially. A preferable average particle diameter is 50 nm to 1000 nm, and more preferably 100 nm to 500 nm.

  The thermoplastic resin fine particles can be pulverized by a general plastic pulverizer, but it is preferable to use a pulverizer equipped with a cooling means capable of maintaining a low temperature so as not to soften and melt the resin during pulverization.

The hydrophobic inorganic fine particles play a dominant role in the content adhesion prevention performance of the lid material, and the material is not particularly limited as long as it is made of a hydrophobic substance having a surface energy of 20 mN / m or more. Specific examples include hydrophobic inorganic fine particles such as hydrophobic silica, alumina, calcium oxide, calcium carbonate, calcium sulfate, and calcium silicate. 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 the primary particles of the hydrophobic inorganic 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 heat sealability may be impaired, and the adhesion preventing effect may be reduced, which is not suitable. A preferred average particle size is in the range of 3 to 500 nm, particularly preferably 3 to 100 nm.

Next, a preferable blending ratio of the thermoplastic resin fine particles and the hydrophobic inorganic fine particles is 10 to 90% by weight: 90 to 10% by weight in a weight ratio of the thermoplastic resin fine particles (solid content): the hydrophobic inorganic fine particles. . Even if the amount of the hydrophobic inorganic fine particles is small, if it is contained in an amount of 10% by weight or more, relatively good adhesion preventing performance can be obtained. Even when the adhesion preventing layer is formed thin, if the blending amount of the hydrophobic inorganic fine particles is less than 10% by weight, the desired content adhesion preventing performance is insufficient. On the other hand, when the amount exceeds 90% by weight, the sealing property with the container and the heat sealing property are deteriorated, and the adhesion to the heat sealing layer is insufficient, and the fine powder itself or the adhesion preventing layer is formed. It is easy for partial dropout and peeling off. 40% by weight of the hydrophobic inorganic fine particles is used in order to ensure sufficient adhesion prevention performance while maintaining good sealing and heat sealing properties with the container and ensuring sufficient adhesion. It should be set as described above, and particularly preferably, it should be set in the range of more than 50% by weight to 80% by weight, assuming that the hydrophobic inorganic fine particles are relatively more contained than the thermoplastic resin fine particles.

  In the production of the anti-adhesion lid according to the present invention, the method for forming the anti-adhesion layer (6) also has a significant influence on the content adhesion prevention performance of the lid.

The anti-adhesion layer (6) is formed by preparing a coating liquid by uniformly dispersing predetermined amounts of thermoplastic resin fine particles and hydrophobic inorganic fine particles in a liquid dispersion medium, and applying this to the outer surface of the heat sealing layer of the lid body. It is carried out by applying to and drying.

The coating liquid is prepared by dispersing thermoplastic resin fine particles and hydrophobic inorganic fine particles using an organic liquid dispersion medium to obtain a colloidal solution having a predetermined concentration. The dispersion medium particularly has an organic dispersion medium having a polar group. Is preferably used. Of these, the use of alcohols is preferred, and the use of methanol or ethanol is particularly preferred from the standpoints of cost, safety, water repellency, and the like. It has been found that when a solvent having no polar group, such as toluene, is used, the anti-adhesion performance is impaired. Although the mechanism is still unclear, it is presumed that the wax in the heat-sealing layer is partially dissolved by toluene and the adhesiveness with the hydrophobic silica particles becomes too high.

  Any known method can be employed for coating the coating liquid. For example, a gravure coating method, spraying, a bar coating method, etc. can be arbitrarily adopted.

The coating amount of the coating solution may be set according to the thickness of the adhesion preventing layer, but is preferably about 0.1 to 5.0 g / m ^{2 by} weight after drying, and preferably 0.2 to 1.0 g / m. ² is more preferable, and it is optimal to set it in the range of 0.4 to 0.8 g / m ² . If it is less than 0.1 g / m ² , the content adhesion preventing effect may be insufficient. On the other hand, if it exceeds 5.0 g / m ² , the cost is increased and there is a risk that the fine particles may fall off.

  The drying process after application is also an important factor. Naturally, it may be naturally dried, but in order to improve productivity and adhesion to the heat sealing layer, it should be dried by heating. In this case, the drying conditions are a temperature of 80 to 140 ° C., a time of 5 to 30 seconds. Should be set in the range. 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, 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 properties of the hydrophobic fine particles are increased. It has been confirmed that the aqueous properties are impaired. Incidentally, the mechanism of the hydrophobicity decrease due to the heat effect 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), the following three types were prepared.

Hot melt type: Wax: 40 parts by weight, rosin: 5 parts by weight, silicon oil: 1 part by weight, ethylene-vinyl acetate copolymer: remaining, a hot melt agent having a composition of 18 g / m ^The coating was carried out by a gravure coating method at a ratio of ² to form a hot melt type heat sealing layer.

  ・ Sealant film type: A 30μm thick sealant film consisting of an easy-peel film of polyethylene as the main component was laminated by extrusion lamination through a urethane adhesive layer to form a sealant film type heat sealing layer. .

・ Lacquer type: A heat seal lacquer composed of main component acrylic resin and polyester resin is applied by a gravure coating method at a rate of 5 g / m ² as a material suitable for a lid for a container made of polystyrene. A heat sealing layer was formed.

(Formation of adhesion prevention layer)
As the material for the adhesion preventing layer, the following thermoplastic resin fine particles and hydrophobic inorganic fine particles were prepared.

Thermoplastic resin fine particles A: Ethylene-vinyl acetate copolymer (vinyl acetate 20%, ethylene 80%, average particle size 100 nm)
B: Vinyl acetate-vinyl chloride copolymer (vinyl acetate 20%, vinyl chloride 80%, average particle size 100 nm)
C: Vinyl acetate-vinyl chloride-maleic acid copolymer (vinyl acetate 20%, vinyl chloride 78%, maleic acid 2%, average particle size 100 nm)
D1: Polyethylene (density 0.900 g / cm ³ , MFR ³ g / 10 min, average particle size 100 nm)
D2: Polyethylene (density 0.900 g / cm ³ , MFR ³ g / 10 min, average particle size 500 nm)
E: A + D1 mixture (A: 80%, D1: 20%)
F: Ethylene-methacrylic acid copolymer (methacrylic acid content 10% by weight, average particle size 100 nm)

Hydrophobic inorganic fine particle P1: Hydrophobic silica Primary particle average particle diameter 7nm
P2: Hydrophobic silica Primary particle average particle size 3 nm
P3: Hydrophobic silica Primary particle average particle diameter 100 nm
P4: Hydrophobic silica Primary particle average particle size 500 nm
P5: Alumina primary particle average particle size 100 nm

The various thermoplastic resin fine particles and hydrophobic inorganic fine particles were uniformly dispersed in ethanol to prepare a coating solution. Table 1 shows the blending ratio of the thermoplastic fine particles and the hydrophobic fine particles.

  Then, these various coating liquids are applied to the outer surface of the heat sealing layer of the lid body by a gravure coating method with various coating amounts and drying conditions as shown in Table 1, and then forcedly dried and adhered. A prevention layer was formed.

(Type of preparation sample)
Of samples 1 to 30 of the various lid materials shown in Table 1 obtained as described above, samples 1 to 15 are affected by changing the blending ratio and coating amount of the hydrophobic inorganic fine particles and the thermoplastic resin fine particles in the adhesion preventing layer. Was investigated.

  Samples 16 and 17 were obtained by examining the influence of different types of heat sealing layers (hot melt, sealant film, lacquer) in the lid body.

Samples 18 to 21 are obtained by using hydrophobic silica and alumina having different average particle diameters as the hydrophobic inorganic fine particles.

Samples 22 to 27 were prepared by changing the type of the thermoplastic resin fine particles used for the adhesion preventing layer to other types of thermoplastic fine particles other than the ethylene-vinyl acetate copolymer.

  Samples 28 to 30 were examined in relation to the method of manufacturing the lid material, and the influence of changing the coating amount and the drying conditions of the coating liquid for forming the adhesion preventing layer.

(Evaluation test)
(1) Anti-adhesion performance Each sample No. Aloe yoghurt (Trademark “Morinaga Aloe Yogurt” manufactured by Morinaga Milk Industry Co., Ltd.) is dropped on the back of 1-30 lid, that is, 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.
◎ ・ ・ ・ 15 degrees or less ○ ・ ・ ・ 16 degrees or more and 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 30 of the cover body (paper / polyethylene container, but the polystyrene container for the cover material of sample No. 17) under the hot-pressure sealing condition of 120 to 180 ° C. × 0.2 MPa × 1.0 sec. Heat sealed on the flange surface.

The seal strength decrease rate or increase rate is determined based on the following criteria, using the seal strength (peeling resistance and sealability of the lid material) of the lid material as it is without an adhesion prevention layer as the reference value. evaluated.
◎ ・ ・ ・ Reduced strength or increase less than 10% ○ ・ ・ ・ Reduced strength or increase 10% to less than 20% × ・ ・ ・ Reduced strength or increased 20% or more

(3) Adhesion Sample No. A weight (500 g) wrapped with a black cloth was placed vertically on the surface of the anti-adhesion layer of each of the lid materials 1 to 30, and slowly rubbed by a length of 200 mm, and visually inspected for the presence of fine particles adhering to the cloth surface. .

And it evaluated by the following evaluation criteria by the transfer adhesion amount (peeling amount) of the hydrophobic inorganic fine particles and the thermoplastic resin fine particles in the black cloth.
◎ ・ ・ ・ Almost no adhesion ○ ・ ・ ・ Slight adhesion that is considered acceptable range × ・ ・ ・ Clearly much adhesion

  Table 2 shows the results of the evaluation tests (1) to (3).

As shown in the results of the “anti-adhesion performance” test in Table 2, in the contents anti-adhesion 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 anti-adhesion layer does not significantly impair both heat sealability (seal strength) and easy-openability, while maintaining appropriate sealability while preventing adhesion. Can give performance. In addition, as seen in "adhesion" test results, a good adhesion of the hydrophobic inorganic fine particles and anti-adhesion layer containing it, separation shedding of such undesirable hydrophobic inorganic fine particles, anti-adhesion layer There is no fear of partial peeling, and the content adhesion preventing performance can be stably maintained over a long period of time, and there is no possibility of foreign matter entering the container.

Claims (12)

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 adhesion preventing layer is composed of a mixed composition of thermoplastic resin fine particles and hydrophobic inorganic fine particles having adhesion to the surface layer of the container body, and the thermoplastic resin fine particles and the hydrophobic inorganic fine particles have a polar group. A lid for preventing content adhesion, which is formed by applying and drying a coating liquid prepared by dispersing in a liquid dispersion medium .   2. The content adhesion preventing lid material according to claim 1, wherein the thermoplastic resin fine particles are made of an olefin resin or a resin composition containing an olefin resin as a main component.   The content adhesion prevention cover material according to claim 2 in which said olefin system resin is polyethylene, polypropylene, or ethylene-unsaturated ester copolymer.   The content according to claim 3, wherein the ethylene-unsaturated ester copolymer is an ethylene-vinyl acetate copolymer, a vinyl acetate-vinyl chloride copolymer, or a vinyl acetate-vinyl chloride-maleic acid copolymer. Adhesion prevention lid.   The content adhesion prevention lid material according to any one of claims 1 to 4, wherein the thermoplastic resin fine particles have an average particle diameter of 1 nm to 5,000 nm. The content adhesion prevention lid material according to any one of claims 1 to 5, wherein the hydrophobic inorganic fine particles are hydrophobic silica. The content adhesion prevention lid material according to any one of claims 1 to 6, wherein the hydrophobic inorganic fine particles have an average particle diameter of 1 nm to 5,000 nm. Compounding ratio of the thermoplastic resin particles and hydrophobic inorganic fine particles in the mixed composition of claim 1 thermoplastic resin particles 10 to 90% by weight, 90 to 10 wt% hydrophobic inorganic fine particles in the solid content ratio 8. The content adhesion preventing lid material according to any one of 7 above. The content adhesion prevention cover material according to any one of claims 1 to 8, wherein the mixed composition contains relatively more hydrophobic inorganic fine particles than the thermoplastic resin fine particles. Dispersion having a polar group on the outer surface of the heat sealing layer of the lid, and a thermoplastic resin particles and hydrophobic inorganic fine particles having an adhesion to the surface layer of the container body having at least a substrate layer and the heat sealing layer After coating the coating liquid prepared by dispersing in a medium so that the weight is 0.1 to 5.0 g / m ² after drying, the coating liquid is dried under drying conditions of a temperature of 80 to 140 ° C. and a time of 5 to 30 seconds. A method for producing a content adhesion prevention lid material, comprising forming an adhesion prevention layer. The method for producing a content adhesion preventing lid material according to claim 10 , wherein the dispersion medium is alcohol . The method for producing a content adhesion preventing lid according to claim 11 , wherein the dispersion medium is methanol or ethanol .

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