JP2013035559A - Content sticking preventive lid material and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lid material mainly applied to a container for packing yogurt, and effectively preventing the yogurt stored therein from sticking to a rear face of a lid while favorably maintaining heat-sealing properties and sealing performance.SOLUTION: A sticking preventive layer 6 is separately formed on an outer surface of a heat sealing layer 5 laminated on a base material layer 1. The sticking preventive layer 6 is constituted of a mixed composition of a binder consisting of an acid modified polyolefine resin as a main component and hydrophobic inorganic fine particles.

Description

  The present invention is mainly applied to heat-sealing lid materials applied to food packaging containers, and more specifically to packaging cup-shaped containers such as yogurt, jelly, pudding, jam, cafe latte, and portion milk. In particular, the present invention relates to a lid material having a content adhesion preventing property 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.

  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.

  This problem is particularly a concern when the lid is suitable for a polystyrene container or a polypropylene container in which a lacquer type heat sealant is used for the heat sealing layer.

  In view of the above-mentioned problems in the prior art, the present invention is intended to further improve, specifically, even in the case of a lid material using a lacquer-type heat sealant in the heat sealing layer. In addition, while maintaining a stable and good heat sealing performance, the adhesion of the hydrophobic inorganic fine particle layer, which is excellent in content adhesion prevention performance and also exhibits the adhesion prevention effect, to the heat sealing layer, the lid material and the container It aims at providing the new improvement technique which can improve adhesiveness and can improve the stability sustainability of the said content adhesion prevention effect.

  In the present invention, in order to achieve the above object, the inventors have conducted various experiments and researches, and as a result, a specific resin as a binder, i.e., an acid-modified polyolefin resin, is used to form an adhesion preventing layer formed on the heat sealing layer. It has been found that the intended purpose can be effectively achieved by comprising a mixed composition of hydrophobic inorganic fine particles as a water repellency imparting component and a binder mainly composed of the above acid-modified polyolefin resin. Based on these findings, the project has been completed.

  Therefore, first, the following means [1] to [7] are presented as an invention in which the content adhesion preventing lid member 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 comprises a mixed composition of hydrophobic inorganic fine particles and a binder mainly composed of an acid-modified polyolefin resin.

  [2] The heat sealing layer is one or more of polyester resins, acrylic resins, polyolefin resins, acid-modified polyolefin resins, vinyl chloride-vinyl acetate copolymer resins, and styrene resins. The content adhesion prevention lid material according to the preceding item [1], which comprises a lacquer-type heat sealant containing as a main component.

  [3] The content adhesion prevention lid according to [1] or [2] above, wherein the amount of the unsaturated carboxylic acid or anhydride thereof contained in the acid-modified polyolefin resin is 0.001 to 3% by weight. Wood.

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

  [5] The content adhesion preventing lid material according to any one of [1] to [4], wherein the hydrophobic inorganic fine particles are hydrophobic silica.

  [6] The content adhesion preventing lid material according to [5], wherein the hydrophobic inorganic fine particles are hydrophobic wet silica having an average particle diameter of 500 nm to 5,000 nm.

[7] The content according to any one of [1] to [6], wherein the mixed composition contains relatively more hydrophobic inorganic fine particles than a binder mainly composed of the acid-modified polyolefin resin. Adhesion prevention lid.
The present invention also presents the means of the following items [8] to [12] characterized by the preparation of the coating liquid, the selection of the solvent, the drying conditions of the coating film, etc. .

[8] Prepared by dispersing hydrophobic inorganic fine particles in an emulsion or a solution of a binder mainly composed of an acid-modified polyolefin resin 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 the coating solution so that the weight is 0.1 to 5.0 g / m ² after drying, the coating solution is dried under drying conditions of a temperature of 80 to 220 ° C. and a time of 5 to 180 seconds to form an adhesion preventing layer. A method for manufacturing a content adhesion prevention lid material.

  [9] The heat sealing layer is one or more of polyester resins, acrylic resins, polyolefin resins, acid-modified polyolefin resins, vinyl chloride-vinyl acetate copolymer resins, and styrene resins. The manufacturing method of the content adhesion prevention lid | cover material of the preceding clause [8] which consists of a lacquer type heat seal agent which has as a main component.

  [10] The content adhesion prevention lid according to [8] or [9] above, wherein the amount of the unsaturated carboxylic acid or anhydride thereof contained in the acid-modified polyolefin resin is 0.001 to 3% by weight. A method of manufacturing the material.

  [11] The method for producing a content adhesion preventing lid material according to any one of [8] to [10], wherein the coating liquid uses a solvent capable of dissolving the acid-modified polyolefin resin.

  [12] The above item [11], wherein the solvent is one or more of n-heptane, n-hexane, cyclohexane, methylcyclohexane, acetone, methylethyltoluene, toluene, ethyl acetate, methanol, and ethanol. Manufacturing method of the content adhesion prevention lid.

  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 prevention effect, the adhesion prevention effect is also achieved by including a binder mainly composed of an acid-modified polyolefin resin in the adhesion prevention layer. Without compromising, the binding strength between the primary and secondary particles of hydrophobic inorganic fine particles that are inherently poor in binding properties is compensated, and at the same time, the adhesion to the heat-sealing layer is improved, and unintentional particles Can be prevented from falling off, and the adhesion preventing layer can be prevented from being peeled off, thereby maintaining a stable content adhesion preventing effect over a long period of time. In addition, the inclusion of the above-mentioned acid-modified polyolefin resin as a main component in the adhesion preventing layer acts to supplement the heat sealing property of the heat sealing layer, and the lid material can be used regardless of the presence of hydrophobic inorganic fine particle groups. Good, stable and strong heat sealability and sealability for the container body can be secured.

  In addition, as described in the above item [2], the heat sealing layer is a lid made of a lacquer type heat sealing agent, and is particularly suitable for a polystyrene container or a polypropylene container. Even in the case of a lid material that is compatible with containers such as those that are bonded to the inner layer, the above effects can be expressed without regret.

  Moreover, as described in the above item [3], the amount of unsaturated carboxylic acid or anhydride thereof contained in the acid-modified polyolefin resin is 0.001 to 3% by weight, so that hydrophobic inorganic fine particles It is possible to increase the adhesive strength to the heat sealing layer to a necessary and sufficient level, and to exhibit good heat sealing characteristics with the container. In particular, it is foreseen that the anti-adhesion layer consisting of hydrophobic inorganic fine particles will inherently impair the heat sealability by interposing as a contaminant between the heat sealing layer and the adherend surface on the container body side where it is heat sealed. However, by optimizing the modification rate with the unsaturated carboxylic acid or its anhydride, it is possible to easily adjust the heat seal characteristics in consideration of the influence of the anti-adhesion layer, and the best sealing state can be realized.

  Further, by using hydrophobic inorganic 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. It can be realized reliably.

  In addition, as described in the above item [5], when hydrophobic silica is selectively used for the hydrophobic inorganic fine particles, an excellent content adhesion preventing effect is achieved with a relatively inexpensive material that is easily available from the market. can do.

  Moreover, as described in the above item [6], when using hydrophobic wet silica having an average particle diameter in a specific range, it is possible to achieve an excellent content adhesion preventing effect more reliably.

  Further, as described in the above item [7], by forming the adhesion preventing layer with a mixed composition in which the blending amount of the hydrophobic inorganic fine particles is set to be relatively larger than that of the binder, the content always good in the adhesion preventing layer is achieved. An object adhesion preventing performance can be imparted.

  Moreover, according to the manufacturing method of the content adhesion prevention cover material as described in said [8] 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.

  In the production methods described in the items [9] and [10], the lid material having the excellent effect described in the items [2] and [3] can be obtained.

  As described in the above item [11], by using a solvent capable of dissolving the acid-modified polyolefin resin for the adjustment of the coating liquid, an adhesion preventing layer having better adhesion preventing performance can be formed.

  Moreover, when the solvent which consists of 1 type (s) or 2 or more types among cyclohexane, methylcyclohexane, acetone, methyl ethyl toluene, toluene, ethyl acetate, methanol, ethanol as described in the said [12] term | claim, said [ 11] 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. 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 comprises a mixed composition of a binder mainly composed of an acid-modified polyolefin resin and hydrophobic inorganic fine particles.

  Acid-modified polyolefin resin is linear low density polyethylene (LLDPE), low density polyethylene (LDPE), very low density polyethylene (VLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), ethylene-vinyl acetate. Copolymer (EVA), ionomer, ethylene-propylene (block or random) copolymer, ethylene-acrylic acid ester copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer Polyolefin resins such as coalesced polyolefins, polybutenes, polypentenes, and the like, or copolymers such as copolymers modified with acids such as unsaturated carboxylic acids or anhydrides, specifically unsaturated carboxylic acids or anhydrides thereof. Addition reaction or graft reaction to polyolefin resin And modified polyolefin resins containing carboxyl groups obtained by chemically bonding, particularly acid graft modified polyolefin resins are preferred, and more specifically maleic anhydride graft modified polyethylene, maleic anhydride. Selected from acid graft modified polypropylene, maleic anhydride graft modified ethylene-propylene (block or random) copolymer, maleic anhydride graft modified ethylene-ethyl acrylate copolymer, maleic anhydride graft modified ethylene-vinyl acetate copolymer, etc. One kind or a mixture of two or more kinds is preferable. The modification rate of the acid-modified polyolefin resin at this time, that is, the amount of unsaturated carboxylic acid or anhydride thereof contained in the acid-modified polyolefin resin is preferably in the range of 0.001 to 3% by weight, more preferably. Is 0.01 to 2% by weight, particularly preferably 0.03 to 1% by weight. If the amount of modification in the modified polyolefin resin is small, the adhesiveness may be insufficient. On the other hand, if the amount is large, a crosslinking reaction may occur and it may be difficult to obtain a uniform coating film.

  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 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. When using hydrophobic silica, either dry silica or wet silica can be used, but the use of wet silica is more advantageous in terms of adhesion prevention performance.

  The average particle diameter 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. It is particularly preferable to use hydrophobic wet silica particles having an average particle diameter of 500 to 5000 nm.

  Next, a preferable blending ratio of the binder mainly composed of the acid-modified polyolefin resin and the hydrophobic inorganic fine particles is 5 to 49% by weight: 95 to 51% by weight in a weight ratio of binder (solid content): fine particles. . If the blending amount of the hydrophobic inorganic fine particles is 51% by weight or more, good adhesion preventing performance can be obtained relatively easily. That is, it is preferable to contain relatively more hydrophobic inorganic fine particles than the binder mainly composed of the acid-modified polyolefin resin, and specifically, it is particularly preferable to set it in the range of 60 to 85% by weight.

  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 adhesion preventing layer (6) is formed by uniformly dispersing a predetermined amount of hydrophobic inorganic fine particles in an emulsion or solution of a binder to prepare a coating solution, and applying this to the outer surface of the heat sealing layer of the lid body. This is done by drying.

  In preparing the coating solution, it is desirable to use a solvent capable of dissolving the acid-modified polyolefin resin used in the binder as a solvent for swelling the heat sealing layer. As such a solvent, organic solvents such as n-heptane, n-hexane, cyclohexane, methylcyclohexane, acetone, methyl ethyl ketone, toluene, ethyl acetate, methanol, and ethanol can be used. From the standpoint of the expression effect, etc., a mixed solvent of cyclohexane, methylcyclohexane, methyl ethyl ketone, and toluene is preferable.

  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 required 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 3.0 g / m. ² is more preferable, and it is optimal to set it in the range of 0.5 to 2.0 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. Arise. If the binder component is excessively small, the structure strength and adhesion of the content adhesion preventing layer itself are insufficient, and as a result, the possibility of peeling or dropping off 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, if 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 inorganic fine particles sink into the heat sealing layer and the hydrophobicity and water repellency of the adhesion preventing layer are impaired. It has been confirmed that

  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 an anchor coating agent is applied to the aluminum vapor-deposited polyethylene terephthalate film of the base material layer, a lacquer heat sealant (A) described below is suitable as a lid for a polystyrene container by a gravure coating method. ) And (B), a heat sealing layer having a coating amount of 5 g / m ² was formed. The base material layer / anchor coating agent / heat sealing layer laminate thus obtained was used as a lid body.

<Heat seal layer>
Lacquer type heat sealant A: Main component is acrylic resin and polyester resin
Heat-seal lacquer Lacquer-type heat sealant B: The main component is acid-modified polypropylene resin
Acid graft modification modification rate 1.0%)
Add tackifier and anti-blocking agent to this.
Heat seal lacquer

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

<binder>
Acid-modified polyolefin resin
Acid-modified PO (I): acid-modified polypropylene resin (maleic anhydride graft modification)
Denaturation rate 0.5%)
Acid-modified PO (II): acid-modified polypropylene resin (maleic anhydride graft modification modification rate 1.0%)
Acid-modified PO (III): acid-modified polypropylene resin (maleic anhydride graft modification)
Denaturation rate 2.0%)
Unmodified PO: Polypropylene resin (maleic anhydride graft modification)
Denaturation rate 0%)

<Hydrophobic inorganic fine particles>
SP (I): Hydrophobic wet silica average particle diameter 2700 nm
SP (II): Hydrophobic wet silica average particle size 3900 nm
SP (III): Hydrophobic dry silica Primary particle average particle size 7 nm

  In a solution obtained by diluting the above various binders with a 50:50 mixed solvent of methyl ethyl ketone and methylcyclohexane, hydrophobic inorganic 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 19 of the various lid materials shown in Table 1 obtained above, Samples 1 to 4 change the binder in the anti-adhesion layer, Samples 5 and 6 change the hydrophobic inorganic fine particles, and Samples 7 and 8 9 and 9 are obtained by changing the coating amount, and Samples 10, 11 and 12 are obtained by changing the blending ratio of the hydrophobic inorganic fine particles and the binder and examining the influence thereof. The heat sealing layer was changed from Sample 13, and the influence was examined by changing the blending ratio and coating amount of the hydrophobic inorganic fine particles and the binder. Further, Samples 18 and 19 were examined by changing the drying conditions.

(Evaluation test)
(1) Anti-adhesion performance Each sample No. Aloe yogurt (Trademark “Morinaga Aloe Yogurt” manufactured by Morinaga Milk Industry Co., Ltd.) is dropped as a 0.5 cc droplet on the back of the lid material 1-19, 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 and 90 degrees or less × ・ ・ ・ 90 degrees or more

(2) Sealability Sample No. The lid materials 1 to 19 were heat-sealed on the flange surface of the container body (polystyrene container) under the hot-pressure sealing condition of 120 to 180 ° C. × 0.2 MPa × 1.0 sec.
Then, the seal strength (peeling resistance / sealing strength of the lid material) in the lid material as it is without the adhesion preventing layer was used as a reference value, and the rate of decrease in the seal strength was judged and evaluated according to the following criteria.
◎ ・ ・ ・ Approximately equivalent to those without adhesion prevention layer ○ ・ ・ ・ Strength reduction less than 10% △ ・ ・ ・ Strength reduction 10% to less than 20% × ・ ・ ・ Strength reduction 20% or more

(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 19, and slowly rubbed by a length of 200 mm, and the silica adhered to the cloth was visually confirmed.
Then, the transfer amount (peeling amount) of the hydrophobic inorganic 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 “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 means that the contents containing viscous liquid components such as yogurt, pudding, jelly, cafe latte and portion milk are excellent in preventing the contents from adhering to the back of the lid. Indicates. 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 can be seen from the results of the “adhesion” test, the hydrophobic particles and the adhesion preventing layer containing them have good adhesion, and unintentional separation and removal of hydrophobic inorganic fine particles, and partial peeling of the adhesion preventing layer. There is no fear of such problems, and the content adhesion preventing performance can be stably maintained over a long period of time, and there is no possibility of foreign matter mixing into the container.

  The present invention is mainly applied to heat-sealing lid materials applied to food packaging containers, and more specifically to packaging cup-shaped containers such as yogurt, jelly, pudding, jam, cafe latte, and portion milk. In particular, the present invention relates to a lid material having a content adhesion preventing property 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.

  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.

  This problem is particularly a concern when the lid is suitable for a polystyrene container or a polypropylene container in which a lacquer type heat sealant is used for the heat sealing layer.

  In view of the above-mentioned problems in the prior art, the present invention is intended to further improve, specifically, even in the case of a lid material using a lacquer-type heat sealant in the heat sealing layer. In addition, while maintaining a stable and good heat sealing performance, the adhesion of the hydrophobic inorganic fine particle layer, which is excellent in content adhesion prevention performance and also exhibits the adhesion prevention effect, to the heat sealing layer, the lid material and the container It aims at providing the new improvement technique which can improve adhesiveness and can improve the stability sustainability of the said content adhesion prevention effect.

  In the present invention, in order to achieve the above object, the inventors have conducted various experiments and researches, and as a result, a specific resin as a binder, i.e., an acid-modified polyolefin resin, is used to form an adhesion preventing layer formed on the heat sealing layer. It has been found that the intended purpose can be effectively achieved by comprising a mixed composition of hydrophobic inorganic fine particles as a water repellency imparting component and a binder mainly composed of the above acid-modified polyolefin resin. Based on these findings, the project has been completed.

  Therefore, first, the following means [1] to [7] are presented as an invention in which the content adhesion preventing lid member 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 comprises a mixed composition of hydrophobic inorganic fine particles and a binder mainly composed of an acid-modified polyolefin resin.

  [2] The heat sealing layer is one or more of polyester resins, acrylic resins, polyolefin resins, acid-modified polyolefin resins, vinyl chloride-vinyl acetate copolymer resins, and styrene resins. The content adhesion prevention lid material according to the preceding item [1], which comprises a lacquer-type heat sealant containing as a main component.

  [3] The content adhesion prevention lid according to [1] or [2] above, wherein the amount of the unsaturated carboxylic acid or anhydride thereof contained in the acid-modified polyolefin resin is 0.001 to 3% by weight. Wood.

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

  [5] The content adhesion preventing lid material according to any one of [1] to [4], wherein the hydrophobic inorganic fine particles are hydrophobic silica.

  [6] The content adhesion preventing lid material according to [5], wherein the hydrophobic inorganic fine particles are hydrophobic wet silica having an average particle diameter of 500 nm to 5,000 nm.

  [7] The content according to any one of [1] to [6], wherein the mixed composition contains relatively more hydrophobic inorganic fine particles than a binder mainly composed of the acid-modified polyolefin resin. Adhesion prevention lid.

  The present invention also presents the means of the following items [8] to [12] characterized by the preparation of the coating liquid, the selection of the solvent, the drying conditions of the coating film, etc. .

[8] Prepared by dispersing hydrophobic inorganic fine particles in an emulsion or a solution of a binder mainly composed of an acid-modified polyolefin resin 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 the coating solution so that the weight is 0.1 to 5.0 g / m ² after drying, the coating solution is dried under drying conditions of a temperature of 80 to 220 ° C. and a time of 5 to 180 seconds to form an adhesion preventing layer. A method for manufacturing a content adhesion prevention lid material.

  [9] The heat sealing layer is one or more of polyester resins, acrylic resins, polyolefin resins, acid-modified polyolefin resins, vinyl chloride-vinyl acetate copolymer resins, and styrene resins. The manufacturing method of the content adhesion prevention lid | cover material of the preceding clause [8] which consists of a lacquer type heat seal agent which has as a main component.

  [10] The content adhesion prevention lid according to [8] or [9] above, wherein the amount of the unsaturated carboxylic acid or anhydride thereof contained in the acid-modified polyolefin resin is 0.001 to 3% by weight. A method of manufacturing the material.

  [11] The method for producing a content adhesion preventing lid material according to any one of [8] to [10], wherein the coating liquid uses a solvent capable of dissolving the acid-modified polyolefin resin.

  [12] The above item [11], wherein the solvent is one or more of n-heptane, n-hexane, cyclohexane, methylcyclohexane, acetone, methylethyltoluene, toluene, ethyl acetate, methanol, and ethanol. Manufacturing method of the content adhesion prevention lid.

  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 prevention effect, the adhesion prevention effect is also achieved by including a binder mainly composed of an acid-modified polyolefin resin in the adhesion prevention layer. Without compromising, the binding strength between the primary and secondary particles of hydrophobic inorganic fine particles that are inherently poor in binding properties is compensated, and at the same time, the adhesion to the heat-sealing layer is improved, and unintentional particles Can be prevented from falling off, and the adhesion preventing layer can be prevented from being peeled off, thereby maintaining a stable content adhesion preventing effect over a long period of time. In addition, the inclusion of the above-mentioned acid-modified polyolefin resin as a main component in the adhesion preventing layer acts to supplement the heat sealing property of the heat sealing layer, and the lid material can be used regardless of the presence of hydrophobic inorganic fine particle groups. Good, stable and strong heat sealability and sealability for the container body can be secured.

  In addition, as described in the above item [2], the heat sealing layer is a lid made of a lacquer type heat sealing agent, and is particularly suitable for a polystyrene container or a polypropylene container. Even in the case of a lid material that is compatible with containers such as those that are bonded to the inner layer, the above effects can be expressed without regret.

  Moreover, as described in the above item [3], the amount of unsaturated carboxylic acid or anhydride thereof contained in the acid-modified polyolefin resin is 0.001 to 3% by weight, so that hydrophobic inorganic fine particles It is possible to increase the adhesive strength to the heat sealing layer to a necessary and sufficient level, and to exhibit good heat sealing characteristics with the container. In particular, it is foreseen that the anti-adhesion layer consisting of hydrophobic inorganic fine particles will inherently impair the heat sealability by interposing as a contaminant between the heat sealing layer and the adherend surface on the container body side where it is heat sealed. However, by optimizing the modification rate with the unsaturated carboxylic acid or its anhydride, it is possible to easily adjust the heat seal characteristics in consideration of the influence of the anti-adhesion layer, and the best sealing state can be realized.

  Further, by using hydrophobic inorganic 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. It can be realized reliably.

  In addition, as described in the above item [5], when hydrophobic silica is selectively used for the hydrophobic inorganic fine particles, an excellent content adhesion preventing effect is achieved with a relatively inexpensive material that is easily available from the market. can do.

  Moreover, as described in the above item [6], when using hydrophobic wet silica having an average particle diameter in a specific range, it is possible to achieve an excellent content adhesion preventing effect more reliably.

  Further, as described in the above item [7], by forming the adhesion preventing layer with a mixed composition in which the blending amount of the hydrophobic inorganic fine particles is set to be relatively larger than that of the binder, the content always good in the adhesion preventing layer is achieved. An object adhesion preventing performance can be imparted.

  Moreover, according to the manufacturing method of the content adhesion prevention cover material as described in said [8] 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.

  In the production methods described in the items [9] and [10], the lid material having the excellent effect described in the items [2] and [3] can be obtained.

  As described in the above item [11], by using a solvent capable of dissolving the acid-modified polyolefin resin for the adjustment of the coating liquid, an adhesion preventing layer having better adhesion preventing performance can be formed.

  Moreover, when using the solvent which consists of 1 type (s) or 2 or more types among cyclohexane, methylcyclohexane, acetone, methylethyltoluene, toluene, ethyl acetate, methanol, and ethanol as described in said [12] said [ 11] 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. 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 comprises a mixed composition of a binder mainly composed of an acid-modified polyolefin resin and hydrophobic inorganic fine particles.

  Acid-modified polyolefin resin is linear low density polyethylene (LLDPE), low density polyethylene (LDPE), very low density polyethylene (VLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), ethylene-vinyl acetate. Copolymer (EVA), ionomer, ethylene-propylene (block or random) copolymer, ethylene-acrylic acid ester copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer Polyolefin resins such as coalesced polyolefins, polybutenes, polypentenes, and the like, or copolymers such as copolymers modified with acids such as unsaturated carboxylic acids or anhydrides, specifically unsaturated carboxylic acids or anhydrides thereof. Addition reaction or graft reaction to polyolefin resin And modified polyolefin resins containing carboxyl groups obtained by chemically bonding, particularly acid graft modified polyolefin resins are preferred, and more specifically maleic anhydride graft modified polyethylene, maleic anhydride. Selected from acid graft modified polypropylene, maleic anhydride graft modified ethylene-propylene (block or random) copolymer, maleic anhydride graft modified ethylene-ethyl acrylate copolymer, maleic anhydride graft modified ethylene-vinyl acetate copolymer, etc. One kind or a mixture of two or more kinds is preferable. The modification rate of the acid-modified polyolefin resin at this time, that is, the amount of unsaturated carboxylic acid or anhydride thereof contained in the acid-modified polyolefin resin is preferably in the range of 0.001 to 3% by weight, more preferably. Is 0.01 to 2% by weight, particularly preferably 0.03 to 1% by weight. If the amount of modification in the modified polyolefin resin is small, the adhesiveness may be insufficient. On the other hand, if the amount is large, a crosslinking reaction may occur and it may be difficult to obtain a uniform coating film.

  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 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. When using hydrophobic silica, either dry silica or wet silica can be used, but the use of wet silica is more advantageous in terms of adhesion prevention performance.

  The average particle diameter 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. It is particularly preferable to use hydrophobic wet silica particles having an average particle diameter of 500 to 5000 nm.

  Next, a preferable blending ratio of the binder mainly composed of the acid-modified polyolefin resin and the hydrophobic inorganic fine particles is 5 to 49% by weight: 95 to 51% by weight in a weight ratio of binder (solid content): fine particles. . If the blending amount of the hydrophobic inorganic fine particles is 51% by weight or more, good adhesion preventing performance can be obtained relatively easily. That is, it is preferable to contain relatively more hydrophobic inorganic fine particles than the binder mainly composed of the acid-modified polyolefin resin, and specifically, it is particularly preferable to set it in the range of 60 to 85% by weight.

  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 adhesion preventing layer (6) is formed by uniformly dispersing a predetermined amount of hydrophobic inorganic fine particles in an emulsion or solution of a binder to prepare a coating solution, and applying this to the outer surface of the heat sealing layer of the lid body. This is done by drying.

  In preparing the coating solution, it is desirable to use a solvent capable of dissolving the acid-modified polyolefin resin used in the binder as a solvent for swelling the heat sealing layer. As such a solvent, organic solvents such as n-heptane, n-hexane, cyclohexane, methylcyclohexane, acetone, methyl ethyl ketone, toluene, ethyl acetate, methanol, and ethanol can be used. From the standpoint of the expression effect, etc., a mixed solvent of cyclohexane, methylcyclohexane, methyl ethyl ketone, and toluene is preferable.

  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 required 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 3.0 g / m. ² is more preferable, and it is optimal to set it in the range of 0.5 to 2.0 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. Arise. If the binder component is excessively small, the structure strength and adhesion of the content adhesion preventing layer itself are insufficient, and as a result, the possibility of peeling or dropping off 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, if 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 inorganic fine particles sink into the heat sealing layer and the hydrophobicity and water repellency of the adhesion preventing layer are impaired. It has been confirmed that

  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 an anchor coating agent is applied to the aluminum vapor-deposited polyethylene terephthalate film of the base material layer, a lacquer heat sealant (A) described below is suitable as a lid for a polystyrene container by a gravure coating method. ) And (B), a heat sealing layer having a coating amount of 5 g / m ² was formed. The base material layer / anchor coating agent / heat sealing layer laminate thus obtained was used as a lid body.

<Heat seal layer>
Lacquer type heat sealant A: Main component is acrylic resin and polyester resin
Heat-seal lacquer Lacquer-type heat sealant B: The main component is acid-modified polypropylene resin
Acid graft modification modification rate 1.0%)
Add tackifier and anti-blocking agent to this.
Heat seal lacquer

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

<binder>
Acid-modified polyolefin resin Acid-modified PO (I): acid-modified polypropylene resin (maleic anhydride graft modification)
Denaturation rate 0.5%)
Acid-modified PO (II): acid-modified polypropylene resin (maleic anhydride graft modification)
Denaturation rate 1.0%)
Acid-modified PO (III): acid-modified polypropylene resin (maleic anhydride graft modification)
Denaturation rate 2.0%)
Unmodified PO: Polypropylene resin (maleic anhydride graft modification)
Denaturation rate 0%)

<Hydrophobic inorganic fine particles>
SP (I): Hydrophobic wet silica average particle diameter 2700 nm
SP (II): Hydrophobic wet silica average particle size 3900 nm
SP (III): Hydrophobic dry silica Primary particle average particle size 7 nm

  In a solution obtained by diluting the above various binders with a 50:50 mixed solvent of methyl ethyl ketone and methylcyclohexane, hydrophobic inorganic 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 19 of the various lid materials shown in Table 1 obtained above, Samples 1 to 4 change the binder in the anti-adhesion layer, Samples 5 and 6 change the hydrophobic inorganic fine particles, and Samples 7 and 8 9 and 9 are obtained by changing the coating amount, and Samples 10, 11 and 12 are obtained by changing the blending ratio of the hydrophobic inorganic fine particles and the binder and examining the influence thereof. The heat sealing layer was changed from Sample 13, and the influence was examined by changing the blending ratio and coating amount of the hydrophobic inorganic fine particles and the binder. Further, Samples 18 and 19 were examined by changing the drying conditions.

(Evaluation test)
(1) Anti-adhesion performance Each sample No. Aloe yogurt (Trademark “Morinaga Aloe Yogurt” manufactured by Morinaga Milk Industry Co., Ltd.) is dropped as a 0.5 cc droplet on the back of the lid material 1-19, 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 and 90 degrees or less × ・ ・ ・ 90 degrees or more

(2) Sealability Sample No. The lid materials 1 to 19 were heat-sealed on the flange surface of the container body (polystyrene container) under the hot-pressure sealing condition of 120 to 180 ° C. × 0.2 MPa × 1.0 sec.
Then, the seal strength (peeling resistance / sealing strength of the lid material) in the lid material as it is without the adhesion preventing layer was used as a reference value, and the rate of decrease in the seal strength was judged and evaluated according to the following criteria.
◎ ・ ・ ・ Approximately equivalent to those without adhesion prevention layer ○ ・ ・ ・ Strength reduction less than 10% △ ・ ・ ・ Strength reduction 10% to less than 20% × ・ ・ ・ Strength reduction 20% or more

(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 19, and slowly rubbed by a length of 200 mm, and the silica adhered to the cloth was visually confirmed.
Then, the transfer amount (peeling amount) of the hydrophobic inorganic 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 “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 means that the contents containing viscous liquid components such as yogurt, pudding, jelly, cafe latte and portion milk are excellent in preventing the contents from adhering to the back of the lid. Indicates. 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 can be seen from the results of the “adhesion” test, the hydrophobic particles and the adhesion preventing layer containing them have good adhesion, and unintentional separation and removal of hydrophobic inorganic fine particles, and partial peeling of the adhesion preventing layer. There is no fear of such problems, and the content adhesion preventing performance can be stably maintained over a long period of time, and there is no possibility of foreign matter mixing into the container.

1. Base material
2 ... Coated paper
3 ... Metal vapor deposition film
4 ... Anchor coat
5 ... Heat sealing layer
6 ... Anti-adhesion layer

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 anti-adhesion layer comprises a mixed composition of hydrophobic inorganic fine particles and a binder mainly composed of an acid-modified polyolefin resin.   The heat sealing layer is mainly composed of one or more of polyester resin, acrylic resin, polyolefin resin, acid-modified polyolefin resin, vinyl chloride-vinyl acetate copolymer resin, and styrene resin. The content adhesion prevention lid material according to claim 1, comprising a lacquer type heat sealant.   The content adhesion prevention cover material according to claim 1 or 2 whose amount of unsaturated carboxylic acid or its anhydride contained in said acid modification polyolefin system resin is 0.001 to 3 weight%.   The content adhesion prevention lid material according to any one of claims 1 to 3, wherein the hydrophobic inorganic 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 4, wherein the hydrophobic inorganic fine particles are hydrophobic silica.   The content adhesion preventing lid material according to claim 5, wherein the hydrophobic inorganic fine particles are hydrophobic wet silica having an average particle diameter of 500 nm to 5,000 nm.   The content adhesion prevention lid material according to any one of claims 1 to 6, wherein the mixed composition contains relatively more hydrophobic inorganic fine particles than a binder mainly composed of the acid-modified polyolefin resin. A coating liquid prepared by dispersing hydrophobic inorganic fine particles in an emulsion or solution of a binder mainly composed of an acid-modified polyolefin resin 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. The coating is applied so that the weight after drying is 0.1 to 5.0 g / m ² and then dried under drying conditions of a temperature of 80 to 220 ° C. and a time of 5 to 180 seconds to form an adhesion preventing layer. A method for manufacturing a content adhesion prevention lid.   The heat sealing layer is mainly composed of one or more of polyester resin, acrylic resin, polyolefin resin, acid-modified polyolefin resin, vinyl chloride-vinyl acetate copolymer resin, and styrene resin. The manufacturing method of the content adhesion prevention lid | cover material of Claim 8 which consists of a lacquer type heat-seal agent.   The method for producing a content adhesion preventing lid material according to claim 8 or 9, wherein an amount of the unsaturated carboxylic acid or anhydride thereof contained in the acid-modified polyolefin resin is 0.001 to 3% by weight.   The method for producing a content adhesion preventing lid material according to any one of claims 8 to 10, wherein the coating liquid uses a solvent capable of dissolving an acid-modified polyolefin resin.   The content adhesion according to claim 11, wherein the solvent comprises one or more of n-heptane, n-hexane, cyclohexane, methylcyclohexane, acetone, methylethyltoluene, toluene, ethyl acetate, methanol, and ethanol. A method for manufacturing a prevention lid.

Images