JP2014031179A - Contents adhering prevention lid member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lid member that is mainly applied to a yoghurt packaging container, the lid member being capable of effectively preventing yoghurt of contents from adhering to the rear face of a lid while keeping favorable heat sealability and sealability.SOLUTION: On the outer face of a heat sealing layer 5 laminated on a base material layer 1, an adhering prevention layer 6 is formed by using hydrophobic wet silica particles which are wet silica particles, and subjected to hydrophobic treatment so that di-n-butylamine adsorption amount (DBA adsorption amount) is 200 mmol/kg or less, preferably 30-100 mmol/kg.

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 material having an adhesion preventing property.

  This type of heat sealing lid is generally 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 film and an aluminum foil, if necessary, via an intermediate resin layer. The package is provided with a layer, and is covered with an upper surface opening of a cup-shaped container body filled with an object to be packaged such as yogurt, and the peripheral portion is heat-sealed on the upper edge flange portion of the container body, thereby sealing the package It is supposed to form.

  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 back surface of the lid material on the inner surface side of the container It is desirable that the content can be prevented from adhering to the 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.

  In response to such a request, conventionally, proposals such as those shown in Patent Documents 1 and 2 below have been made for lid materials having a content adhesion prevention performance.

  According to the prior art disclosed in Patent Document 1, a porous layer having a three-dimensional network structure is formed on the outer surface of the heat sealing layer as a content adhesion preventing layer by hydrophobic oxide fine particles such as fine hydrophobic silica. Is.

  Although the prior proposal technique of this patent document 1 can have an excellent effect in terms of content adhesion prevention effect, the adhesion prevention layer is inferior in thermal stability (heat resistance) and adheres when it receives an unfavorable thermal history. There was a difficulty that the prevention effect was easy to be impaired. That is, as the hydrophobic oxide fine particles, ultrafine hydrophobic oxide fine particles having a primary particle average diameter of 3 to 100 nm, typically silica fine particles produced by a dry method, are used. When applied to the formation of an anti-adhesion layer for the contents of a lid material provided with a general hot-melt type heat sealing layer, the heating temperature during drying after coating of the fine particle dispersion in the anti-adhesion layer forming step If it is high or the drying time is long, the content adhesion preventing effect is remarkably impaired, and stable adhesion preventing performance may not be maintained. For this reason, the process control at the time of manufacture of a lid | cover material had the difficulty that it became a little troublesome.

  Such a heat resistance problem is that when the hot-melt adhesive of the heat-sealing layer is melted by radiant heat from the hot platen during the drying or heat-sealing standby, fine oxide particles are contained in the hot-melt adhesive. Prevents the adhesion of contents by sinking into the gap or filling the gap between the fine particles of the hot melt adhesive by capillarity and filling the gap between the particles, thereby reducing the water-repellent surface area of the hydrophobic silica. This is probably because the effect cannot be obtained sufficiently.

  On the other hand, as an improvement technique that can ensure excellent non-adhesiveness while solving the problem of the prior art, particularly the thermal stability problem of Patent Document 1 as described above, the present inventors. Previously proposed the invention described in Patent Document 2.

  This improvement proposal technique is mainly characterized by using hydrophobic wet silica particles as a material for forming the adhesion preventing layer instead of the conventionally known hydrophobic dry silica. Wet silica particles are generally micron in size and are much larger than dry silica particles. Therefore, when the heat sealing layer is composed of a hot melt adhesive, even if the adhesive melts, the hydrophobic silica particles are unlikely to sink into the heat sealing layer. Accordingly, it is easy to maintain good water repellency on the surface of the adhesion preventing layer. As a result, the influence of heat can be improved as compared with the prior art of Patent Document 1.

  However, on the other hand, since the wet silica particles have a relatively large particle size, compared with the case where dry silica particles comprising aggregates of ultrafine primary particles are used, the coating amount (attachment amount) and The surface water repellency in the relative relationship is poor, and in order to obtain high adhesion prevention performance, it is necessary to apply a little amount of hydrophobic wet silica, and therefore it tends to be inferior in adhesion to the heat sealing layer. There are difficulties, and further improvement of these points has been strongly demanded for practical use.

Japanese Patent No. 4348401 Japanese Patent No. 4668352

  The present invention is to meet the above-mentioned demands in the prior art, specifically, it has good heat resistance that can maintain sufficient content adhesion prevention performance even under the influence of heat, and less Even with the amount of wet silica fine particles applied, high content adhesion prevention performance can be secured, and the adhesion of the hydrophobic wet silica fine particles to the heat sealing layer can be secured well, and the above-mentioned content adhesion prevention effect can be maintained stably. The purpose is to provide improved technology that can be secured.

  As a result of intensive experiments and researches for the above purpose, the present inventors have made the hydrophobic wet silica while forming the anti-adhesion layer with the hydrophobic wet silica according to the prior art of Patent Document 2. In particular, the present inventors have found that the above problems can be solved very effectively by using hydrophobic wet silica particles having a high degree of hydrophobicity of a predetermined value or more that have been subjected to a particularly highly hydrophobic treatment, and to complete the present invention. It came.

  That is, the present invention presents the following configuration as its feature.

[1] In a heat seal lid member having at least a base material layer and a heat sealing layer, and having an adhesion preventing layer provided on the outer surface of the heat sealing layer,
The content adhesion preventing lid material, wherein the adhesion preventing layer is made of hydrophobic wet silica particles having a di-n-butylamine adsorption amount of 200 mmol / kg or less.

  [2] The content adhesion preventing lid material according to [1], wherein the hydrophobic wet silica particles have a di-n-butylamine adsorption amount of 30 to 100 mmol / kg.

[3] The content adhesion preventing lid material according to [1] or [2], wherein a coating amount of the hydrophobic wet silica particles in the adhesion preventing layer is 0.1 to 1.0 g / m ² .

  [4] The content adhesion preventing lid material according to any one of [1] to [3], wherein an average particle diameter of the hydrophobic wet silica particles is 6.0 μm or less.

  In the invention of item [1], hydrophobic wet silica particles having a relatively large particle size are used for forming the adhesion preventing layer on the heat sealing layer. Therefore, when the heat sealing layer is formed of a hot melt adhesive and the adhesive melts, the particles are heat sealed as much as the particle size is larger than when ultrafine dry silica is used. It is difficult to sink into the layer and does not greatly reduce the exposed area of its surface. As a result, it is possible to effectively prevent a decrease in the adhesion preventing performance due to the influence of heat. This is the same as the prior art shown in Patent Document 2 above, but in the present invention, the hydrophobic wet silica particles are particularly highly hydrophobized wet silica, specifically, Hydrophobized wet silica particles whose surface is treated with a di-n-butylamine adsorption amount of 200 mmol / kg or less are used. Such hydrophobic silica particles have a very high water repellency on their own surface, and therefore, the anti-adhesion layer formed with the hydrophobic wet silica has a relatively small amount of silica particles applied. Demonstrates excellent adhesion prevention performance. In addition, since a small coating amount is sufficient, the fixing property and adhesion of the silica particles to the heat-sealing layer can be kept good, and the silica particles fall off due to insufficient adhesion, the performance over time due to peeling, and poor hygiene. Can be avoided.

  Here, the adsorption amount of di-n-butylamine of hydrophobic silica (hereinafter referred to as “DBA adsorption amount”) serves as an index representing the degree of hydrophobicity. That is, normal silica has a large amount of silanol groups, which are hydrophilic groups, on its surface, regardless of whether it is a dry process or a wet process. Di-n-butylamine reacts with silanol groups and is adsorbed on silica particles in an ionic bond. On the other hand, hydrophobic silica originally replaces hydrophilic surface particles with hydrophobic groups typified by methyl groups by hydrophobizing hydrophilic silica particles having silanol groups on the surface with silanes or silicones. Manufactured by. However, even when the hydrophobic treatment is performed, not all of the surface hydrophilic groups are replaced with hydrophobic groups, and some unreacted silanol groups are inevitably left. In particular, in the case of wet silica particles, the particle structure of itself is composed of a large number of aggregates of very small fine particles, and has a porous structure with a large number of micropores inside, so that there is no reaction inside. The hydrophilic silanol group remains. Therefore, the degree of hydrophobicity of the silica particles can be known by adsorbing di-n-butylamine to the hydrophobized silica particles and measuring the amount of adsorption.

  Further, the hydrophobic wet silica particles have a certain amount of silanol groups remaining unreacted on the surface and inside as described above. Since this silanol group is hydrophilic, it is inferior in affinity to the heat-melted resin component and consequently blocks the penetration of the resin component. That is, even when the low melting point resin component of the heat sealing layer is melted due to the high heat effect applied during heat sealing, it is prevented from rapidly penetrating into the gaps between the silica particles and the micropores inside the particles due to capillary action. Act on. For this reason, the water-repellent surface is prevented from being greatly diminished by excessively covering the particle surface and internal voids with the resin component, and performance deterioration due to thermal influence is reduced. That is, it can contribute to the improvement of the heat resistance of the adhesion preventing layer.

  Further, as described in the above item 2, when using hydrophobic wet silica particles in which the DBA adsorption amount is controlled in the range of 30 to 100 mmol / kg, due to the high hydrophobicity and surface water repellency of itself. Furthermore, it is possible to realize further excellent adhesion prevention performance and good adhesion.

In addition, as described in [3] above, by setting the coating amount (adhesion amount) of the hydrophobic silica particles to 0.1 to 1.0 g / m ² in terms of weight after drying, the adhesion preventing layer is formed. Necessary and sufficient adhesion prevention performance can be imparted.

  Furthermore, as described in the above item [4], by using hydrophobic wet silica particles having an average particle size of 6.0 or less, good adhesion to the heat sealing layer can be maintained, The heat sealing property of the sealing layer is not hindered, and excellent performance that is uniform and stable in terms of sealing strength and container sealing performance can be exhibited.

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

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

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

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

  The metal foil layer (3) imparts gas barrier properties, light shielding properties, etc., and aluminum foil is often used. In particular, in the case of a lid for a coffee beverage or yogurt container, an aluminum foil having a thickness of about 5 to 100 μm is preferably used to satisfy light shielding properties and light weight. Moreover, a general adhesive agent is used for lamination | stacking adhesion | attachment with a base film layer (2).

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

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

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

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

  By the way, the anti-adhesion layer (6) which constitutes the main component of the present invention is made hydrophobic by chemically reacting an organic silicon compound with a hydroxyl group on the surface of wet silica particles which are synthetic amorphous silica produced by a wet method. Hydrophobic wet silica particles imparted with properties, and in particular, composed of wet silica particles highly hydrophobized so that the DBA adsorption amount (di-n-butylamine adsorption amount) is 200 mmol / kg or less. It is characterized by. The present invention uses such hydrophobic wet silica particles hydrophobized to a DBA adsorption amount of 200 mmol / kg or less, so that the particles themselves have extremely high water repellency, and thus high content at a small coating amount. It is possible to provide a lid material having an object adhesion prevention performance.

  The reason is presumed as follows.

  First, by using wet silica particles, the particles have many surface silanol groups in the production stage, and as a result, when the surface is hydrophobized, they generally exhibit superior water repellency and hydrophobicity compared to dry silica. That is, compared to dry silica particles that are aggregates of primary particles that do not have pores inside, wet silica particles not only have a large particle size, but also have a large number of fine pores that can take in air inside, and the particle size The specific surface area is large and the pore volume is large. For this reason, the hydrophobized wet silica particles exhibit excellent water repellency and hydrophobicity by a synergistic action of the action of the hydrophobic group substituted on the surface and the action of air taken into the micropores. In addition, in the present invention, the use of highly hydrophobized hydrophobic wet silica particles in which the wet silica particles themselves exhibit a DBA adsorption amount of 200 mmol / kg or less is further used. It exhibits high water repellency and often exhibits excellent adhesion prevention performance.

  Here, in the present invention, the DBA adsorption amount indicating the degree of hydrophobicity of the wet silica particles is defined to be 200 mmol / kg or less because of experimental results. That is, when using hydrophobic wet silica particles having an adsorption amount of DBA exceeding 200 mmol / kg, the adhesion preventing layer cannot exhibit good adhesion preventing performance under a small coating amount. On the other hand, if the coating amount is increased for that purpose, the adhesion of the silica particles itself to the heat-sealing layer is deteriorated, and the possibility that the adhesion preventing layer may drop off and partially peel off increases.

  However, even if wet silica particles are sufficiently hydrophobized as described above, not all of the hydrophilic groups on the surface are replaced by hydrophobic groups, and some hydrophilic silanol groups inevitably remain. . Although this residual silanol group does not contribute to water repellency, it has poor affinity for the molten resin component due to its hydrophilicity, which in turn contributes to ensuring the heat resistance stability of the adhesion preventing layer. In other words, the adhesion prevention layer is formed even when the low melting point component of the heat sealing layer melts and fluidizes due to the high heat effect received from the heating plate at the time of forced heating drying after coating formation of the adhesion prevention layer or heat sealing. The above-mentioned molten resin component penetrates into the gaps between the silica particles and the minute internal voids of the particles themselves by capillarity to prevent the deterioration of adhesion prevention performance due to covering the hydrophobic surface of the particles to some extent. It is thought that it contributes to the improvement of heat resistance. For this reason, it is preferable that the DBA adsorption amount has a value of 30 mmol / kg or more when the relationship with the difficulty in the production of hydrophobic silica is taken into consideration. Therefore, the preferable DBA adsorption amount range of the hydrophobic wet silica is 30 to 100 mmol / kg.

  In addition, it is desirable that the hydrophobic wet silica particles used in the present invention have an average particle size of 6.0 μm or less, particularly preferably in the range of 0.2 to 5.0 μm.

  When coarse particles having an average particle size exceeding 6.0 μm are used, not only the adhesion to the heat sealing layer (5) is deteriorated but also the heat sealing property may be impaired. On the other hand, when small particles of less than 0.2 μm are used, it is generally impossible to obtain a good content adhesion preventing effect within a range of coating amount and adhesion amount that does not adversely affect heat sealability. Preferably, the average particle diameter is in the range of 2.0 to 5.0 μm.

The adhesion amount (coating amount) of the hydrophobic wet silica particles in the adhesion preventing layer (6) is in the range of 0.1 to 1.0 g / m ² , preferably 0.2 to 0.5 g / m. A range of ² is set. When the adhesion amount of the hydrophobic wet silica particles is less than the above lower limit value of 0.1 g / m ² , a good content adhesion preventing effect cannot be obtained. On the other hand, when the adhesion amount exceeds the above upper limit value of 1.0 g / m ² , the content adhesion preventing effect is saturated, while the adhesion preventing layer (6) inhibits the heat sealing property of the heat sealing layer (5). Specifically, the sealing strength (peeling resistance) is lowered by 20% or more as compared with the case where the adhesion preventing layer (6) is not provided, and there is a possibility that the stable and good sealing performance of the container is impaired. In addition, the adhesion with the heat sealing layer (5) is also lowered.

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

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

  The dispersion concentration of the hydrophobic silica particles in the dispersion can be arbitrarily set in consideration of the relationship with the coating amount of the particles, but a sufficient amount of hydrophobic silica is less than 2% (particles 2 g: solvent 100 ml). It is difficult to uniformly apply particles, and the coating amount tends to be excessive at a high concentration exceeding 10%. A suitable dispersion concentration is about 3 to 6%.

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

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

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

Next, various experimental examples conducted to confirm the effect of the present invention and the results thereof will be shown.
(Preparation of lid body)
A polyethylene terephthalate film having a thickness of 12 μm was used as the substrate film (2), and an aluminum foil (3) having a thickness of 30 μm was bonded to one surface thereof with a polyurethane-based dry laminate adhesive to obtain a substrate layer (1).

Next, an intermediate resin layer (4) is formed by laminating and bonding a 20 μm thick polyethylene film to the surface of the base material layer (1) on the aluminum foil (3) side using the same adhesive as described above. A heat sealing layer (5) was formed on the outside by a gravure coating method. The laminate of the base material layer (1) / intermediate resin layer (4) / heat sealing layer (5) obtained in this way was used as the lid body. Here, as the heat sealing layer (5), a hot melt adhesive having a composition of 55% by weight of ethylene-vinyl acetate copolymer / 40% by weight of wax / 5% by weight of a tackifier (rosin) was used. The amount was 18 g / m ² .
(Formation of adhesion prevention layer)
As hydrophilic wet silica particles produced by a wet method, the following three types having different particle sizes were prepared.

Wet silica A ... average particle size 1.7μm
Wet silica B ... average particle size 2.7μm
Wet silica C ... average particle size 6.7μm
Then, all of the wet silicas A, B, and C are hydrophobized using dimethylpolysiloxane as a hydrophobizing agent, and the DBA adsorption amount serving as a hydrophobic index for each is 30 mmol / kg, 100 mmol / kg, Four types of hydrophobic wet silica particles each having values of 200 mmol / kg and 250 mmol / kg were prepared.

Next, various hydrophobic wet silica particles are dispersed in an ethanol solvent at a dispersion concentration of 5% to prepare various dispersions, and these various dispersions are used as the heat sealing layer of the lid body. As shown in Tables 1 and 2, the outer surface of (5) was coated under various coating amounts in the range of 0.05 to 1.5 g / m ² as shown in Tables 1 and 2, followed by forced drying, and a heat sealing layer ( 5) Various samples were obtained on which the content adhesion preventing layer (6) composed of the hydrophobic wet silica particles was formed. The coating amounts shown in Tables 1 and 2 indicate the weight ratio of the hydrophobic wet silica particles after drying.
(Evaluation test)
And the following evaluation test was done about each sample.
(1) Anti-adhesion performance Aloe yoghurt (Trademark “Morinaga Aloe Yoghurt” manufactured by Morinaga Milk Industry Co., Ltd.) was dropped on the back of the lid of each sample, that is, the outer surface of the anti-adhesion layer, as about 0.5 cc droplets. When the sample was tilted slowly, the “tilt angle when the droplet started to roll” was measured and evaluated according to the following criteria.

◎ ・ ・ ・ 15 degrees or less ○ ・ ・ ・ 16 degrees or more and 30 degrees or less △ ・ ・ ・ 31 degrees or more and 45 degrees or less × ・ ・ ・ 46 degrees or more (2) Adhesiveness Surface of the adhesion preventing layer of the lid of each sample Then, a weight (500 g) wrapped with a black cloth was placed vertically, slowly rubbed with a length of 200 mm, and the amount of silica adhering to the cloth was visually inspected.

  And the transfer adhesion amount (peeling amount) of the hydrophobic wet silica particles in the black cloth was evaluated according to the following evaluation criteria.

◎ ・ ・ ・ No adhesion ○ ・ ・ ・ Slight adhesion that is accepted as acceptable range △ ・ ・ ・ Some adhesion × ・ ・ ・ Clearly much adhesion Result of the adhesion prevention performance evaluation test (1) above Table 1 shows the results of the adhesion evaluation test (2).

First, as shown in the test results of “adhesion prevention performance” in Table 1, in samples using hydrophobic wet silica having a DBA adsorption amount of 200 mmol / kg or less indicating the degree of hydrophobicity as an adhesion prevention layer forming material. When the application amount (adhesion amount) is 0.1 g / m ² or more, both exhibit sufficiently excellent adhesion prevention performance. When the DBA adsorption amount is 250 mmol / kg, satisfactory adhesion preventing performance cannot be obtained even if the coating amount is considerably increased. Further, the size of the silica particles does not significantly affect the above performance.

  Further, as shown in the test results of “Adhesion” in Table 2, the adhesion of the hydrophobic wet silica particles in the adhesion preventing layer is almost the same in all systems using the hydrophobic wet silica having different DBA adsorption amounts. It shows good adhesion such that there is no adhesion (drop off) or some adhesion is observed. As the tendency, the smaller the coating amount, the higher the adhesion, and when the average particle size of the silica particles is too large, the adhesion tends to decrease. It can be presumed that this tendency is simply due to the increase in the amount of the hydrophobic wet silica that falls off as the coating amount increases and as the particle size becomes larger than approximately 6.0 μm. From this, it was found that the DBA adsorption amount of the hydrophobic wet silica of the wet silica does not have a great influence on the adhesion.

Based on the above results, the anti-adhesion layer is formed using hydrophobic wet silica particles having a DBA adsorption amount of 200 mmol / kg or less, preferably 100 mmol / kg or less. It was confirmed that sufficient adhesion prevention performance and adhesion could be exhibited in the range of / m ² .

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

Claims (4)

In a heat seal lid material having at least a base material layer and a heat sealing layer, and an adhesion preventing layer provided on the outer surface of the heat sealing layer,
The content adhesion preventing lid material, wherein the adhesion preventing layer is made of hydrophobic wet silica particles having a di-n-butylamine adsorption amount of 200 mmol / kg or less.   The content adhesion prevention cover material according to claim 1 whose di-n-butylamine adsorption amount of said hydrophobic wet silica particles is 30-100 mmol / kg. The content adhesion prevention lid | cover material of Claim 1 or 2 whose application quantity of the hydrophobic wet silica particle in the said adhesion prevention layer is 0.1-1.0 g / m < ² >.   The content adhesion prevention lid | cover material of any one of Claims 1-3 whose average particle diameter of hydrophobic wet silica particle is 6.0 micrometers or less.

Images