JP2013039930A - Lid material for preventing deposition of content, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lid material mainly applied to a yogurt container, which preferably maintains heat sealing properties and sealing performance, and effectively prevents yogurt, which is the content, from depositing on the back side of a lid.SOLUTION: An additional deposition prevention layer 6 is formed on an outside of a heat-sealable layer 5 laminated on a base material layer 1. The deposition prevention layer 6 is made from a mixed composition of: a thermoplastic resin binder composed of an ethylene-unsaturated ester copolymer, etc.; and hydrophobic wet silica fine particles.

Description

  The present invention relates to a heat-sealing lid material mainly applied to containers for packaging foods, more specifically, contents applied to cup-shaped containers for packaging such as yogurt, jelly, pudding, jam, and cafe latte. The present invention relates to a lid member having anti-adhesion properties and a method for manufacturing the same.

  This type of heat sealing lid material is provided with, for example, 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 flange part of the container body. It has been made.

  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.

  In this prior proposed technology, the super-water-repellent level of the porous layer has an extremely excellent water repellency, which is very effective in preventing the adhesion of contents, but oxidation of extremely fine hydrophobic silica or the like. The porous layer with a three-dimensional network structure composed of fine particles itself is structurally brittle and has poor adhesion to the adjacent heat-sealing layer, resulting in partial peeling and dropping of the porous layer. It was easy, and there was a possibility that foreign matter was mixed into the packaged contents, which was not preferable in terms of hygiene.

  In addition, since the porous layer made of oxide fine particles becomes a contaminant in the heat seal portion, the uniform sealing that is stable over the entire circumference of the seal portion due to uneven application of the oxide fine particles. It was difficult to obtain adhesion strength and peel resistance, and the smooth easy-opening property of the lid material could be hindered.

  In order to solve the above-mentioned problems, the inventors of the present application (Japanese Patent Application No. 2010-052794) have hydrophobic inorganic fine particles typified by dry silica composed of fused fine particles of ultrafine primary particles. Is used as a mixture with a thermoplastic resin binder, and an adhesion preventing layer is formed on the heat sealing layer with this mixed composition, thereby increasing the bonding force between the inorganic fine particles by the binder resin, and the heat sealing layer. We have just proposed an improvement technology that will improve the adhesion of the machine.

  This prior proposed technique has sufficient effectiveness for achieving the intended purpose.

  However, on the other hand, in the actual production of the lid material performed in accordance with the prior proposal technique, the preparation of the dispersion coating liquid by the mixed composition with the agitation essential for obtaining uniform diffusion of the inorganic fine particles, the uniform Each process such as coating and drying after coating requires fairly strict condition management, and there is a risk that even if a slight deviation from the process management conditions, the anti-adhesion performance desired for the anti-adhesion layer may not be obtained. It has turned out that there is.

  The present invention is intended to further improve the above-mentioned problems, specifically, while maintaining stable and good heat seal performance, it is excellent in content adhesion prevention performance and also exhibits the adhesion prevention effect. An object of the present invention is to provide a new improvement technology that can improve the adhesion and stability of the content adhesion preventing effect by improving the adhesion between the heat-sealing layer of hydrophobic fine particles and the adhesion between the lid and the container. .

  In the present invention, in order to achieve the above-mentioned object, the inventors have conducted various experiments and researches. As a result of accidental discoveries, porous silica made by a wet process and having a relatively large particle size is obtained. By using hydrophobic wet silica particles that have hydrophobicity on the surface, the risk of unintentional reduction in the anti-adhesion performance as described above can be significantly reduced even in combination with a thermoplastic resin binder. It has been found that it can be improved, and has been completed based on such knowledge.

  Therefore, first, the following means [1] to [5] are presented as an invention in which the content adhesion preventing lid material is an object.

[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 anti-adhesion layer uses hydrophobic wet silica particles imparted with hydrophobicity to the surface of porous silica particles obtained by a wet process as a water repellency imparting component, and a mixture of the hydrophobic wet silica particles and a thermoplastic resin binder. A content adhesion preventing lid material comprising a composition.

  [2] The thermoplastic resin binder described above, wherein the thermoplastic resin binder has a melting point or a softening point of 80 ° C. or more, and contains a synthetic resin as a main component having adhesion to both the heat sealing layer and the container. The content adhesion prevention lid material according to [1].

  [3] The preceding item [1] or [2], wherein the thermoplastic resin binder comprises one or more of an ethylene-unsaturated ester copolymer, an acrylic resin, and a polyester resin. The content adhesion prevention cover material of description.

  [4] The content adhesion preventing lid material according to any one of [1] to [3], wherein the hydrophobic wet silica particles have an average particle diameter of 100 nm to 5,000 nm.

  [5] The content adhesion preventing lid material according to any one of [1] to [4], wherein the mixed composition contains relatively more hydrophobic wet silica particles than the thermoplastic resin binder.

  The present invention also presents the means of the following items [6] to [9] characterized by the adjustment of the coating liquid, the selection of the solvent, the drying conditions of the coating film, etc. .

[6] A coating liquid prepared by dispersing hydrophobic wet silica particles in an emulsion or solution of a thermoplastic resin binder is dried 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. After coating to a weight of 0.1 to 5.0 g / m ² after drying, the adhesion preventing layer is formed by drying under drying conditions of a temperature of 80 to 220 ° C. and a time of 5 to 180 seconds. A method of manufacturing a content adhesion prevention lid.

  [7] The content adhesion preventing lid material according to [6], wherein the thermoplastic resin binder is one or more of ethylene-unsaturated ester copolymer, acrylic resin, and polyester resin. Manufacturing method.

  [8] The method for producing a content adhesion preventing lid material according to [6] or [7] above, wherein the coating liquid uses a solvent that dissolves or swells the heat sealing layer.

  [9] The preceding items [6] to [8], wherein the solvent is one or more of n-heptane, n-hexane, cyclohexane, methylcyclohexane, methylethyltoluene, toluene, ethyl acetate, methanol, ethanol, acetone. ] The manufacturing method of the content adhesion prevention lid | cover material of description.

  In the constitution of the above item [1], the present invention corresponds to the blending ratio by adding hydrophobic wet silica fine particles to the content adhesion preventing layer provided in addition to the outer surface of the heat sealing layer. In addition to being able to express the necessary and sufficient content adhesion prevention effect as desired, the adhesion-preventing layer also contains a thermoplastic resin binder, so that hydrophobic wetness originally lacking in binding properties While supplementing the bonding force between the silica particles, it also improves the adhesion to the heat-sealing layer and prevents unintentional particle removal and peeling of the anti-adhesion layer for long-term stable content adhesion prevention. The effect can be maintained. In addition, the inclusion of the thermoplastic resin binder in the anti-adhesion layer acts to supplement the heat sealability of the heat seal layer, and is good for the container body of the lid regardless of the presence of hydrophobic wet silica fine particle groups. Stable and strong heat sealability and sealability can be secured.

  The enjoyment of such effects has been confirmed by the results of experiments conducted by the present inventors, and the reasoning mechanism is not yet clear, but is presumed to be due to the following reasons. The That is, dry silica (fumed silica) produced by a dry process, which has been generally put to practical use as a water repellency-imparting component of the anti-adhesion layer, is an ultrafine solid having a particle size of several nanometers to several tens of nanometers Primary agglomerated particles are formed as a minimum unit in which a large number of primary particles adjoin in the three-dimensional direction are firmly fused and joined in a chain shape. In the normal state, the primary agglomerated particles are further physically bonded to form a secondary agglomerate that can be sheared and separated. Therefore, when the hydrophobic dry silica particles obtained by subjecting such dry silica particles to hydrophobicity imparting processing are stirred in a solvent containing a binder, the aggregated particles present in the state of primary aggregated particles in the solvent are: The binder is entangled with the surface of the primary particle which is the structural unit. As a result, when the solvent is removed after coating to form an anti-adhesion layer, many of the hydrophobic surfaces of the primary particles are covered with the binder, which reduces the original hydrophobic performance and prevents the expected adhesion. It is presumed that there is a situation where performance cannot be obtained.

  On the other hand, when using hydrophobic wet silica particles by a wet process instead of the above dry silica particles, the particles themselves have a relatively large particle size of micron size, and the surface has an uneven structure to prevent adhesion. In addition to exhibiting the effect, the particles themselves are porous, have a large specific surface area, and have a large pore volume and oil absorption. For this reason, when mixing and stirring in a binder solvent, even if a part of the surface of the hydrophobic wet silica particles may be covered by the adhesion of the binder, a sufficient exposed area is still maintained on the surface of the particles. As a result, even after the solvent is removed to form the adhesion preventing layer, the exposed area of the hydrophobic surface is not drastically reduced, and a good content adhesion preventing effect is exhibited. In addition, since the wet silica particles are porous as described above and have a large pore area, especially when the binder and the heat sealing layer contained in the adhesion preventing layer are melted during heat sealing. It is possible to prevent the wet silica particles themselves from rapidly absorbing the low melting point and low molecular weight components and filling the voids between the particles with the molten components. This also contributes to maintaining the voids between the particles and securing the exposed area of the hydrophobic surface of the particles, and contributing to the maintenance of a good content adhesion preventing effect after heat sealing.

  Further, in the configuration described in the above item [2], the use of a thermoplastic resin binder having a melting point or softening point of 80 ° C. or more causes a slight and severe heat influence in the heat drying process or the heat sealing process. Even if there is, the substrate side of the anti-adhesion layer containing the hydrophobic wet silica fine particles in harmony with it without greatly impairing the anti-adhesion effect by the hydrophobic wet silica fine particles due to the significant decrease in the melt viscosity of the binder Adhesiveness to the heat sealing layer can be more reliably and firmly maintained.

  Further, as described in the above [3], when a binder composed of one or more of an ethylene-unsaturated ester copolymer, an acrylic resin, and a polyester resin is used as a binder, The effect by the structure of said [1] term can be achieved more favorably.

  Further, by using hydrophobic wet silica fine particles having an average particle size as described in the above item [4], the above-described content adhesion preventing effect can be obtained using a relatively inexpensive material that is easily available from the market. And the improvement effect of the adhesiveness with respect to a heat sealing layer can be implement | achieved more reliably.

  In addition, as described in the above item [5], when the amount of the hydrophobic fine particles to be distributed is relatively larger than that of the binder, it is possible to always impart good content adhesion prevention performance to the adhesion prevention layer.

  Moreover, according to the manufacturing method of the content adhesion prevention lid | cover material as described in the said [6] term, the lid | cover material which shows the effect by the said [1] term can be obtained simply and reliably. 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.

  In the manufacturing method as described in said [7] term, the lid | cover material which has the outstanding effect as described in said [4] term can be obtained.

  As described in the above item [8], by using a solvent that dissolves or swells the heat sealing layer in the preparation of the coating liquid, the heat sealing layer is obtained without impairing the adhesion preventing effect of the hydrophobic wet silica fine particles. Adhesion to can be obtained with certainty.

  In addition, as described in the above item [9], one or more of n-heptane, n-hexane, cyclohexane, methylcyclohexane, methylethyltoluene, toluene, ethyl acetate, methanol, ethanol, and acetone are mixed. When a solvent is used, the corresponding effect of item [8] can be obtained 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 is, as an example of a lid material suitable for a container for yogurt packaging, generally coated paper (2) having a printing (7) surface protected with a coating agent (2a) and a metal vapor deposition film (3). A laminated body bonded with an adhesive is used as a base material (1), and a heat sealing layer (5) is provided on the outer surface of the base material (1) on the metal vapor deposition film (3) side via an anchor coat (4). It is what was done. This laminated structure is the same as that of a conventionally known lid material, and the laminated body including the base material (1) and the heat sealing layer (5) is referred to as a “lid material body” herein.

  For example, in the case of a lid for a packaging container for liquid beverages such as Caffe Latte, the lid body is not shown in the figure, but generally an aluminum foil having a required printing on one surface on the outer surface side. And a heat sealing layer is provided on the other surface of this substrate via an intermediate resin layer as necessary.

  The content adhesion preventing lid material according to the present invention is such that an adhesion preventing layer (6) is additionally provided on the outer surface of the heat sealing layer (5) of the lid material body.

  A metal vapor deposition film (3) provides gas barrier property, light-shielding property, etc., and an aluminum vapor deposition polyester film is used in many cases. Particularly in the case of a lid for a yogurt container, an aluminum vapor-deposited polyester film having a thickness of about 12 to 16 μm is suitably used as a light-shielding property and light weight. In addition, a general adhesive is used for laminating and bonding with the coated paper (2).

  The material of the heat sealing layer (5) is not particularly limited as long as it has good adhesion to the container side. For example, a hot melt agent, a lacquer type heat sealant, or a known sealant film can be used. In particular, for a lid for a polystyrene container for packaging such as yogurt, it is common and preferred to use a lacquer type heat sealant. For example, a lacquer type mainly composed of one or more of polyester resins, acrylic resins, polyolefin resins, acid-modified polyolefin resins, vinyl chloride-vinyl acetate copolymer resins, and styrene resins. It is preferable to use a heat sealant.

  Moreover, after apply | coating the polyester-type lacquer agent with sufficient adhesiveness with a polyester film, it can also select suitably that the other lacquer agent which is excellent in the sealing performance with a container is applied.

  The thickness of the heat sealing layer (5) is not particularly limited, but is generally about 1 to 30 μm in thickness from the viewpoint of cost, sealing performance, productivity, etc. It is good to set it as the range of 2-20 micrometers.

  By the way, the adhesion preventing layer (6) constituting the main component of the present invention is composed of a mixed composition of a thermoplastic resin binder and hydrophobic wet silica fine particles as a water repellency imparting component.

  The material of the thermoplastic resin binder is not particularly limited, but has a melting point or softening point of 80 ° C. or higher, and is well-suited to the heat sealing layer (5) and the hydrophobic wet silica fine particles. It is desirable to select and use a thermoplastic resin that exhibits adhesiveness and also has good adhesiveness to the surface layer of the container body, and at least includes 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. Examples of particularly preferable binder resins include ethylene-unsaturated ester copolymers, polyacrylates, polymethyl methacrylates, and polyethylene terephthalates. A binder containing at least one of them as a main component is used. The most favorable results can be obtained.

  Hydrophobic wet silica fine particles are composed of hydrophobic wet silica particles obtained by chemically reacting hydroxyl groups on the surface of wet silica particles, which are synthetic amorphous silica produced by a wet method, with an organic silicon compound to impart hydrophobicity. .

  Wet silica has more surface silanol groups than dry silica, and even in hydrophobic particles after the surface has been hydrophobized with silanes or silicones, it has superior water repellency and hydrophobicity compared to dry silica. Indicates. Further, as described above, wet silica particles not only have a large particle diameter, but also have a larger particle size than the dry silica particles whose primary unit is the aggregate of primary particles having no pores. Large specific surface area, large pore volume and oil absorption. 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 heat stability of the adhesion preventing effect The improvement effect cannot be achieved sufficiently. 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 having various particle sizes can be produced at the production stage, but in the application of the present invention, particles having an average particle size in the range of 100 nm to 5000 nm should be used. It is.

  When fine particles having an average particle size of less than 100 nm 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 5000 nm are used, not only the adhesion to the heat sealing layer (5) is deteriorated, but also the heat sealing property is hindered. Preferably, the average particle diameter is in the range of 500 nm to 4000 nm.

  Next, a preferable blending ratio of the thermoplastic resin binder and the hydrophobic wet silica fine particles is 5 to 49% by weight: 95 to 51% by weight in a weight ratio of binder (solid content): fine particles. When the blending amount of the hydrophobic fine particles is 51% by weight or more, relatively good adhesion preventing performance can be obtained.

  Particularly preferably, it should be set in the range of 60 to 85% by weight as containing relatively larger amounts of hydrophobic wet silica fine particles than the thermoplastic resin binder.

  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 uniformly dispersing a predetermined amount of hydrophobic wet silica fine particles in a binder emulsion or solution to prepare a coating solution, which is applied to the outer surface of the heat sealing layer of the lid body. Done by drying.

  For the adjustment of the coating solution, an organic solvent such as n-heptane, n-hexane, cyclohexane, methylcyclohexane, methyl ethyl ketone, toluene, ethyl acetate, methanol, ethanol, and acetone can be used as a solvent for swelling the heat sealing layer. However, a mixed solvent of n-heptane, n-hexane, cyclohexane, methylcyclohexane, toluene and methyl ethyl ketone, ethyl acetate, and acetone is particularly preferable from the standpoints of cost, safety, and water repellency.

  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 0.3 to 2.0 g / m. ² is more preferable, and it is optimal to set it in the range of 0.5 to 1.0 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 it is necessary to increase the binder component in order not to lower the heat sealability. In that case, the content adhesion preventing effect may not be sufficiently obtained. When the amount of the binder component is small, the content adhesion preventing layer may drop off, which is not preferable.

  The drying process after application is also an important factor. Naturally, it may be naturally dried, but in order to enhance productivity and adhesion with the heat sealing layer, it should be dried by heating. In this case, the drying conditions are a temperature of 80 to 220 ° C., a time of 5 to 180 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 220 ° C. or the time is set to a time exceeding 180 seconds, the hydrophobic wet silica fine particles sink into the heat sealing layer, and the hydrophobicity and water repellency of the adhesion preventing layer are reduced. It has been confirmed that it will be damaged.

  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 coated paper (55 g / m ² ) and a 16 μm thick aluminum vapor-deposited polyethylene terephthalate film were used, and they were bonded together with a polyurethane-based dry laminate adhesive to form a base material layer.

  Next, after applying an anchor coating agent to the aluminum vapor-deposited polyethylene terephthalate film of the base material layer, a heat sealing layer was further formed thereon by a gravure coating method. The base material layer / anchor coating agent / heat sealing layer laminate thus obtained was used as a lid body.

  Here, as the heat sealing layer (5), the following three types were prepared.

・ Lacquer type (A): Gravure coating method using heat seal lacquer (A) consisting of main component acrylic resin and polyester resin at a rate of 5 g / m ² as a suitable material for lids of polystyrene containers. Was applied to form a lacquer-type heat sealing layer.

・ Lacquer type (B): Suitable as a lid for polystyrene containers, main component acid-modifying polypropylene resin (maleic anhydride graft-modification modification rate: 1.0%), tackifier, anti-blocking agent A heat seal lacquer (B) consisting of the above was applied at a rate of 5 g / m ^{2 by} a gravure coating method to form a lacquer type heat sealing layer.

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

(Formation of adhesion prevention layer)
The following binder and hydrophobic fine particles were prepared as materials for the adhesion preventing layer.

Binder A: Ethylene-methacrylic acid copolymer (melting point 95 ° C., methacrylic acid content 10% by weight)
B: Polymethylmethacrylate (softening point 105 ° C)
C: ethylene-vinyl acetate copolymer (melting point 82 ° C., vinyl acetate content 20%)
D: Polyethylene wax (melting point 67 ° C.)

Hydrophobic fine particles SP (I): Hydrophobic wet silica Average particle size 2700 nm
SP (II): Hydrophobic wet silica average particle size 3900 nm
SP (III): Hydrophobic wet silica average particle size 1300 nm
SP (IV): hydrophobic dry silica primary particles 10 nm

  In a solution obtained by diluting the above various binders with a 50:50 mixed solvent of methyl ethyl ketone and methylcyclohexane, hydrophobic fine particles were mixed at various blending ratios shown in Table 1 and uniformly dispersed to prepare a coating solution.

  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)
Among samples 1 to 20 of the various lid materials shown in Table 1 obtained as described above, samples 1 to 3 and 5 were examined by changing the type of binder in the adhesion preventing layer. Sample 4 has no binder. Samples 6 and 7 were obtained by changing the particle size of the hydrophobic wet silica fine particles and examining the influence thereof.

  The kind of heat sealing layer was changed from sample 8. Samples 8 to 9 and 17 are the coating amounts, and samples 11 to 13 and 16 are the ones obtained by examining the influence of various blending ratios of the hydrophobic wet silica particles and the binder.

  Samples 14 and 15 were obtained by examining the effect of changing the type of heat sealing layer in the lid body to the sealant type.

  Sample 18 used hydrophobic dry silica fine particles (primary particle diameter 10 nm) instead of hydrophobic wet silica fine particles, and Samples 19 and 20 examined the influence by changing the drying conditions of the coating liquid.

(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 the lid material 1-20, that is, on the outer surface of the adhesion preventing 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

(2) Sealability Sample No. Heat the lid material of 1 to 20 on the flange surface of the container body (polystyrene container, sample Nos. 14 and 15 are polyethylene containers) under a hot-pressure sealing condition of 120 to 180 ° C. × 0.2 MPa × 1.0 sec. Sealed.

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 vertically placed on the surface of the adhesion preventing layer of each of the lid materials 1 to 20, 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.
◎ ・ ・ ・ 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 “adhesion prevention” test in Table 2, 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 above adhesion prevention performance can be imparted while maintaining good sealing performance without significantly impairing the heat sealability (seal strength) due to the presence of the adhesion prevention layer. In addition, as seen in the results of the “adhesion” test, the adhesion of the hydrophobic particles and the anti-adhesion layer containing them is good, and unintentional separation of hydrophobic fine particles, partial peeling of the anti-adhesion layer, etc. It can be confirmed that the content adhesion prevention performance can be stably maintained over a long period of time and there is no problem in terms of hygiene without the possibility of foreign matter mixing into the container.

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Coated paper 3 ... Metal vapor deposition film 4 ... Anchor coat layer 5 ... Heat sealing layer 6 ... Adhesion prevention layer

Claims (9)

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 uses hydrophobic wet silica particles imparted with hydrophobicity to the surface of porous silica particles obtained by a wet process as a water repellency imparting component, and a mixture of the hydrophobic wet silica particles and a thermoplastic resin binder. A content adhesion preventing lid material comprising a composition.   The thermoplastic resin binder has a melting point or softening point of 80 ° C or higher, and contains a synthetic resin having adhesiveness to both the heat sealing layer and the container as a main component. The cover for preventing the contents from being attached.   The said thermoplastic resin binder consists of 1 type (s) or 2 or more types among an ethylene- unsaturated ester copolymer, an acrylic resin, and a polyester-type resin, The content adhesion of Claim 1 or 2 characterized by the above-mentioned. Prevention lid material.   The content adhesion prevention lid material according to any one of claims 1 to 3, wherein the hydrophobic wet silica particles have an average particle diameter of 100 nm to 5,000 nm.   The said mixed composition is a content adhesion prevention lid | cover material of any one of Claims 1-4 which contains relatively many hydrophobic wet silica particles rather than the said thermoplastic resin binder. A coating liquid prepared by dispersing hydrophobic wet silica particles in an emulsion or solution of a thermoplastic resin binder on the outer surface of the heat sealing layer of the lid material having at least a base material layer and a heat sealing layer, by weight after drying. Content application characterized by forming an adhesion preventing layer by applying 0.1 to 5.0 g / m ² and then drying under drying conditions of a temperature of 80 to 220 ° C. and a time of 5 to 180 seconds. A method for manufacturing a prevention lid.   The manufacturing method of the content adhesion prevention lid | cover material of Claim 6 in which the said thermoplastic resin binder consists of 1 type (s) or 2 or more types among an ethylene- unsaturated ester copolymer, an acrylic resin, and a polyester-type resin.   The method of manufacturing a content adhesion preventing lid according to claim 6 or 7, wherein the coating liquid uses a solvent that dissolves or swells the heat sealing layer.   The content according to any one of claims 6 to 8, wherein the solvent comprises one or more of n-heptane, n-hexane, cyclohexane, methylcyclohexane, methylethyltoluene, toluene, ethyl acetate, methanol, ethanol, and acetone. A method for manufacturing an anti-adhesion lid.

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