JP7369509B2 - Water-repellent laminates for lids, lids and containers - Google Patents

Description

The present invention relates to a water-repellent laminate for a lid, a lid, and a container, and more specifically, a water-repellent laminate including a thermal adhesive layer having a specific surface Si element concentration, and a lid produced using the same. Regarding materials and containers.

BACKGROUND ART In many product fields such as foods, beverages, pharmaceuticals, and chemicals, containers and the like have been developed according to the respective contents. Materials with excellent water resistance, oil resistance, gas barrier properties, moisture resistance, light weight, flexibility, and design are used as lids for containers for filling viscous contents such as liquids, semi-solids, and gel-like substances. used to protect the contents.

Further, as a function of the lid material, there is a demand for an adhesion prevention function that can prevent contents having high viscosity such as liquids, semi-solids, and gel-like substances from adhering.

As a means for improving the ability to prevent contents from adhering to the lid material, Patent Document 1 proposes providing a thermal adhesive layer on one side of a base material to which hydrophobic fine particles are attached. Further, Patent Document 2 proposes providing an anti-adhesion layer containing hydrophobic fine particles and a thermoplastic binder resin on one side of a base material.

However, the lid material proposed in Patent Document 1 has low abrasion resistance, and hydrophobic fine particles on the surface may slide off due to friction, so that it may not be able to sufficiently exhibit adhesion prevention and water repellency. There was a problem. Furthermore, the hydrophobic fine particles would slide down into the contents, posing a hygiene problem.
In the lid material proposed in Patent Document 2, when the adhesion prevention layer is formed by applying and drying a coating liquid containing hydrophobic fine particles and a thermoplastic resin binder emulsion, many hydrophobic fine particles are formed. There was a problem in that the adhesion prevention layer was completely buried in the adhesion prevention layer, and the adhesion prevention property and water repellency could not be sufficiently exhibited. Furthermore, an anti-adhesion layer is provided separately from the thermal adhesive layer, which poses a cost problem.

Japanese Patent Application Publication No. 2010-184454 Japanese Patent Application Publication No. 2011-184082

The present inventors have recently found that by incorporating particles having two or more different average particle diameters into the thermal adhesive layer, it is possible to improve the abrasion resistance, and at the time of forming the thermal adhesive layer, It has been found that particles can be prevented from being buried inside.
Furthermore, it has been found that by setting the elemental concentration of Si on the surface of the thermal adhesive layer within a specific numerical range, as measured by X-ray photoelectron spectroscopy, the anti-adhesion properties and water repellency can be more significantly improved.
Therefore, an object of the present invention is to provide a water-repellent laminate for a lid material that can be manufactured with fewer steps and has high abrasion resistance, anti-adhesion properties, and water repellency.

The water-repellent laminate for a lid material of the present invention includes a base material and a thermal adhesive layer on the base material, and the thermal adhesive layer has a thermoplastic resin, water-repellent fine particles, and an average particle size smaller than that of the water-repellent fine particles. It is characterized in that it contains large bead particles, and the Si element concentration on the surface of the thermal adhesive layer, as measured by X-ray photoelectron spectroscopy, is 17% or more.

In the above embodiment, the water-repellent fine particles are preferably SiO ₂ that has been subjected to a hydrophobic surface treatment.

In the above embodiment, the average particle diameter of the water-repellent fine particles is preferably 1 nm or more and 300 nm or less.

In the above embodiment, the average particle diameter of the bead particles is preferably 1 μm or more and 50 μm or less.

In the above embodiment, the content ratio of water-repellent fine particles to bead particles in the thermal adhesive layer is preferably 10:1 to 1:10 on a mass basis.

In the above embodiment, the adhesive layer preferably contains a polyester resin and a vinyl chloride-vinyl acetate copolymer.

The lid material of the present invention is characterized by comprising the above-mentioned laminate.

The container of the present invention includes the above-mentioned lid material and a container main body, and is characterized in that the thermal adhesive layer of the lid material and the container main body are heat-sealed.

The method for producing a water-repellent laminate for a lid material of the present invention includes a step of preparing a base material, and a thermoplastic resin, water-repellent fine particles, and bead particles having a larger average particle size than the water-repellent fine particles on the base material. It includes a process of applying a coating liquid for a thermal adhesive layer and a process of drying the applied coating liquid for a thermal adhesive layer, and in the drying process, the amount of heat added to the coating liquid for a thermal adhesive layer is 0.5 kJ/ m ² or more and 5.5 kJ/m ² or less.

According to the present invention, it is possible to provide a water-repellent laminate for a lid material that can be manufactured with fewer steps and has high abrasion resistance, anti-adhesion properties, and water repellency.

FIG. 1 is a schematic cross-sectional view of a water-repellent laminate for a lid material according to an embodiment of the present invention. FIG. 1 is a schematic cross-sectional view of a container according to an embodiment of the present invention.

<Water-repellent laminate for lid material>
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic cross-sectional view of a water-repellent laminate for a lid material according to an embodiment of the present invention.
In one embodiment, the water-repellent laminate 10 for a lid material includes a base material 11 and a thermal adhesive layer 12 containing water-repellent fine particles 13 and bead particles 14. Each layer constituting the water-repellent laminate for a lid material according to the present invention will be explained below.

(Base material)
As a base material, paper materials such as coated paper, printing paper, high-quality paper, and kraft paper are used, or films made of resins such as polypropylene, polyamide, and polyester such as polyethylene terephthalate (PET), or metal foils such as aluminum foil are used. can do. In addition, since the base material can function as a barrier layer against oxygen and water vapor, it is preferable to deposit an inorganic oxide such as aluminum, silicon oxide, titanium oxide, or aluminum oxide on the paper material or film. . It is also preferable because it can improve the light-shielding properties of the base material. Furthermore, a laminate of the above-mentioned paper material and a film may be used as the base material. The lamination method is not particularly limited, and dry lamination, wet lamination, heat lamination, etc. can be used.

Further, the surface of the base material on which the thermal adhesive layer is laminated can be subjected to surface treatment such as corona discharge treatment, chemical treatment, ozone treatment, etc., as desired.

The base material may be printed using a conventionally known printing ink. The printing method is not particularly limited either, and conventionally known methods such as gravure printing, flexographic printing, and screen printing can be used.

The thickness of the base material is not particularly limited, but may be, for example, 5 μm or more and 200 μm or less.

(thermal adhesive layer)
The thermal adhesive layer included in the laminate of the present invention includes a thermoplastic resin, water-repellent fine particles, and bead particles having a larger average particle size than the water-repellent fine particles.
Since the thermal adhesive layer contains two types of particles with different sizes, a unique uneven structure is formed on the surface, which significantly improves the adhesion prevention property against viscous contents and water repellency. can. Furthermore, the abrasion resistance of the thermal adhesive layer can be improved, and it is possible to prevent these particles from sliding off due to friction and being mixed into the contents. Furthermore, it is possible to prevent these particles from being buried in the thermal adhesive layer during formation of the thermal adhesive layer.

In the laminate of the present invention, the elemental concentration of Si on the surface of the thermal adhesive layer, as measured by X-ray photoelectron spectroscopy, is 17 atomic % or more. Thereby, the water repellency and adhesion prevention properties of the laminate can be improved. The element concentration of Si is more preferably 20 atomic % or more and 50 atomic % or less, and even more preferably 21 atomic % or more and 40 atomic % or less. By setting it within such a numerical range, water repellency and adhesion prevention properties can be further improved while maintaining heat sealability.
Although the Si element concentration on the surface of the thermal adhesive layer is not limited to this, the type and amount of constituent materials such as thermoplastic resin, water-repellent particles, and bead particles, the thickness of the thermal adhesive layer, and the thermal adhesive It can be adjusted by changing the amount of heat applied when forming the layer.
Further, in the present invention, the elemental concentration of Si on the surface of the thermal adhesive layer was measured using an X-ray photoelectron spectrometer under the following conditions.
(Measurement condition)
・X-ray source: Mg Kα ray (1253.6eV)
・X-ray output: 300W (12kV, 25mA)

Thermoplastic resins included in the thermal adhesive layer include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polyolefin resins such as polypropylene, poly(meth)acrylic resins, polyester resins, ionomer resins, and ethylene. -Vinyl resins such as acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-ethyl methacrylate copolymer, polystyrene resin, vinyl chloride-vinyl acetate copolymer, etc. Can be mentioned. Among these, when the container is made of polystyrene, polyester resins, acrylic resins and vinyl chloride-vinyl acetate copolymers are particularly preferred.
The thermal adhesive layer can contain one or more of the above thermoplastic resins, and from the viewpoint of thermal adhesiveness, it is particularly preferable to use a polyester resin and a vinyl chloride-vinyl acetate copolymer together. In addition, by using these resins in combination, water-repellent fine particles and bead particles appear appropriately on the surface of the thermal adhesive layer, making it possible to further improve water repellency and anti-adhesion properties, as well as improving abrasion resistance. You can also do it.

As the water-repellent fine particles contained in the thermal adhesive layer, oxide fine particles subjected to hydrophobic surface treatment, such as SiO ₂ , TiO ₂ , Al ₂ O ₃ and MgO, can be used. Further, CaCO ₃ , talc, mica, etc. can also be used as the water-repellent fine particles.
Among these, SiO ₂ subjected to hydrophobization surface treatment (hereinafter referred to as hydrophobized SiO ₂ in some cases) is preferable from the viewpoints of anti-adhesion properties, water repellency, and cost.
The thermal adhesive layer may contain two or more types of water-repellent fine particles.
The hydrophobic treatment method is not particularly limited, and may be a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a zircoaluminum coupling agent, a phosphoric acid surfactant, or a fatty acid surfactant. This can be done using a surface treatment agent such as oil, fat, wax, or stearic acid.
Alternatively, commercially available oxide fine particles subjected to hydrophobic surface treatment may be used.

The average particle diameter of the water-repellent fine particles is preferably 1 nm or more and 300 nm or less, more preferably 1 nm or more and 200 nm or less, and even more preferably 1 nm or more and 100 nm or less. By setting the average particle diameter of the water-repellent fine particles within the above numerical range, it is possible to further improve the anti-adhesion properties and water repellency while maintaining the heat-sealability of the thermal adhesive layer.
The average particle diameter of the water-repellent fine particles means the arithmetic mean diameter measured by a scanning electron microscope.

The content of water-repellent fine particles in the thermal adhesive layer is preferably 5% by mass or more and 85% by mass or less, more preferably 20% by mass or more and 70% by mass or less. By setting the content of the water-repellent fine particles within the above numerical range, it is possible to further improve the adhesion prevention properties and water repellency while maintaining the heat-sealability of the thermal adhesive layer.
Further, the content of water-repellent fine particles in the thermal adhesive layer is preferably 5 parts by mass or more and 500 parts by mass or less, and 20 parts by mass or more and 200 parts by mass or less, based on 100 parts by mass of the thermoplastic resin contained in the thermal adhesive layer. It is more preferably at most parts by mass, and even more preferably at least 70 parts by mass and at most 170 parts by mass.

Examples of the bead particles included in the thermal adhesive layer include organic resin beads and inorganic beads. Examples of organic resin beads include acrylic resin beads, urethane resin beads, polyethylene resin beads, polystyrene resin beads, styrene-acrylic copolymer beads, polycarbonate resin beads, polyvinyl chloride beads, melamine resin beads, benzoguanamine-formaldehyde condensation beads, Examples include melamine-formaldehyde condensate beads, benzoguanamine-melamine-formaldehyde condensate beads, and benzoguanamine-melamine condensate beads. Examples of inorganic beads include glass beads, silica beads, alumina silicate, talc, and mica.
Among these, silica beads and urethane resin beads are more preferred in terms of stability, cost, and the like. Note that two or more types of the above organic resin beads and/or inorganic beads may be used.

The average particle diameter of the bead particles is preferably 1 μm or more and 50 μm or less, more preferably 3 μm or more and 30 μm or less, and even more preferably 5 μm or more and 20 μm or less. By setting the average particle diameter of the bead particles within the above numerical range, it is possible to further improve the adhesion prevention properties and water repellency while maintaining the heat sealability of the thermal adhesive layer. Furthermore, the abrasion resistance of the thermal adhesive layer can be improved, and water-repellent fine particles can be prevented from falling off due to friction.
The average particle diameter of bead particles can be measured using a scanning electron microscope.

The content of bead particles in the thermal adhesive layer is preferably 5% by mass or more and 85% by mass or less, more preferably 20% by mass or more and 70% by mass or less. By setting the content of bead particles within the above numerical range, it is possible to further improve the adhesion prevention properties and water repellency while maintaining the heat sealability of the thermal adhesive layer. Furthermore, the abrasion resistance of the thermal adhesive layer can also be improved.

The ratio of the content of thermoplastic resin to the content of water-repellent fine particles and bead particles in the thermal adhesive layer is preferably 2:1 to 1:5, and 1.5:1 to 1, based on mass. :3 is more preferable. Thereby, the adhesion prevention properties and water repellency of the thermal adhesive layer can be further improved.

The content ratio of water-repellent fine particles to bead particles in the thermal adhesive layer is preferably from 10:1 to 1:10, more preferably from 8:3 to 3:8, based on mass. Thereby, the adhesion prevention properties and water repellency of the thermal adhesive layer can be further improved.

In one embodiment, the thermal adhesive layer is formed by applying a thermal adhesive layer coating solution containing the above-mentioned materials onto the base material by a known method such as a bar coating method, and drying it in a drying oven. can be done.
The coating amount of the coating liquid for the thermal adhesive layer after drying is preferably 1.0 g/m ² or more and 10 g/m ² or less, and preferably 2.0 g/m ² or more and 7 g/m ² or less. More preferred. If the coating amount of the heat adhesive layer after drying is within the above numerical range, the adhesion prevention properties and water repellency can be further improved while maintaining the heat sealability of the laminate.
In the drying oven, the amount of heat applied to form the thermal adhesive layer is preferably 0.5 kJ/m ² or more and 5.5 J/m 2 or less, and 1.5 kJ/m ^{2 or} more and 4.5 kJ/m 2 or more. It is more preferable that it is below ^m2 , and it is still more preferable that it is 2.0 kJ/ ^m2 or more and 4.0 kJ/ ^m2 or less. By setting the amount of heat applied to form the thermal adhesive layer within the above numerical range, water-repellent fine particles and bead particles will appear appropriately on the surface of the thermal adhesive layer, thereby further improving water repellency and anti-adhesion properties. This amount of heat can be adjusted by controlling the temperature inside the drying oven and the drying time.

(Other layers)
The laminate of the present invention may have one or more other layers between the base material and the thermal adhesive layer. Examples of other layers include a barrier layer, a printing layer, and an anchor layer.

As the barrier layer, for example, metal foil can be used, and more specifically, aluminum foil, stainless steel foil, titanium foil, etc. can be mentioned. Aluminum foil is preferable from the viewpoint of gas barrier properties that block the transmission of oxygen gas, water vapor, etc., and light shielding properties that block the transmission of visible light, ultraviolet rays, etc.

The printing layer is a layer provided to impart design properties such as characters, information, patterns, and pictures to the laminate. The printing layer can be formed using conventionally known pigments and dyes, and the forming method is not particularly limited.
For example, inorganic pigments such as titanium white, zinc oxide, Bengara, vermillion, ultramarine, cobalt blue, titanium yellow, carbon black, isoindolinone yellow, Hansa yellow A, quinacridone red, permanent red 4R, phthalocyanine blue, industhrene blue RS. , organic pigments such as aniline black, metal pigments made of metal powders such as aluminum and brass, pearl pigments made of foil powders such as mica coated with titanium dioxide, and basic lead carbonate, and fluorescent pigments.

The anchor layer is a layer that functions to improve the adhesion between the base material and the thermal adhesive layer and to prevent water-repellent fine particles and bead particles contained in the thermal adhesive layer from slipping off.
The anchor layer can contain a (meth)acrylic resin, a urethane resin, a polyester resin, a cellulose resin, a vinyl resin, or a copolymer of these resins (for example, an acrylic polyester resin).
In addition, hardening agents, silane coupling agents, plasticizers, ultraviolet stabilizers, coloring inhibitors, matting agents, deodorants, flame retardants, weathering agents, antistatic agents, thread friction reducers, slip agents, mold release agents. It may contain various additives such as anti-oxidants, antioxidants, and ion exchange agents.

(lid material)
The lid material according to the present invention can be produced using the above-described laminate, and can be suitably used as a lid material for packaging containers for viscous contents such as liquids, semi-solids, and gel-like substances, such as yogurt. I can do it.

(container)
As shown in FIG. 2, the container 20 according to the present invention includes a lid material 21 made of a water-repellent laminate for lid materials, and a container body 22. is heat sealed. More specifically, the opening 23 of the container body 22 and the thermal adhesive layer 12 of the lid material are heat-sealed.
The heat sealing method is not particularly limited, and can be performed by using conventionally known methods such as bar sealing, high frequency sealing, and ultrasonic sealing.

The container body can be made of polystyrene, polypropylene, polyethylene, paper, or the like. Among these, polystyrene is more preferable because of its good moldability.

The shape of the container body is not particularly limited, and may be a cup shape or a cylindrical shape with a bottom as shown in FIG. 2.

Further, the contents that can be filled into the container are not particularly limited, but include foods such as pudding, yogurt, and jelly, and non-foods such as shampoo and body soap.

The present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

(Example 1)
Preparation of substrate
A pattern was applied to one side of printing paper (manufactured by Daio Paper Co., Ltd., trade name: Ryuoh Coat, 55 g/m ² ) by gravure printing using printing ink (manufactured by DIC Corporation, trade name: SIUS HR). After dry laminating the aluminum-deposited side of the aluminum-deposited PET film on the non-printing side of the printing paper, aging was performed to prepare a base material. Note that a polyether adhesive (manufactured by Rock Paint Co., Ltd., trade name: RU3900) was used for dry lamination.

Preparation of water-repellent laminate for lid material Ink WRD-1 manufactured by Sakuramiya Chemical Co., Ltd. having the following composition as a coating liquid for the thermal adhesive layer was applied onto the PET surface by a bar coating method, so that the coating amount after drying was 2. A heat adhesive layer was formed by applying the mixture to a concentration of 0 g/m ² and drying it in a drying oven, thereby producing a water-repellent laminate for a lid material. Note that a heat amount of 1.0 kJ/m ² was applied to the applied ink WRD-1 in the drying oven.
The Si element concentration on the surface of the thermal adhesive layer of the obtained water-repellent laminate for lid material was measured using an X-ray photoelectron spectrometer under the following measurement conditions, and was found to be 28.8 atomic %.
(Measurement condition)
・X-ray source: Mg Kα ray (1253.6eV)
・X-ray output: 300W (12kV, 25mA)
(Composition of ink WRD-1)
・Resin component (vinyl chloride-vinyl acetate copolymer, olefin resin) 7 parts by mass ・Bead particles (average particle diameter: 1 to 30 nm, SiO ₂ ) 1 part by mass ・Water-repellent fine particles (average particle diameter: 1 to 100 nm, Hydrophobic SiO ₂ ) 5 parts by mass, toluene 40 parts by mass, methyl ethyl ketone 30 parts by mass, ethyl acetate 10 parts by mass

(Examples 2 to 8 and Comparative Example 1)
A water-repellent laminate for a lid material was produced in the same manner as in Example 1, except that the amount of heat applied in the drying oven was changed to the value shown in Table 1.

<Performance evaluation of water-repellent laminate for lid material>
Seal strength test
The heat-adhesive layer of the water-repellent laminate for lid material obtained in Examples and Comparative Examples was heat-sealed to a polystyrene sheet (heat-sealing temperature: 210°C, sealing width 2mm, pressure 0.3MPa, time: 0. 8 seconds). After heat-sealing, the water-repellent laminate for lid material was peeled off using a tensile tester (manufactured by Orientech Co., Ltd.), and the maximum strength at the time of peeling was defined as the sealing strength (N/15 mm) (peeling angle 180°, tensile speed 300mm/min). The measurement results are shown in Table 1.

Water repellency test Using a contact angle meter (manufactured by Kyowa Kaimen Kagaku), the contact angle between the water droplet and the thermal adhesive layer of the water-repellent laminates for lid materials obtained in Examples and Comparative Examples was measured, and the contact angle was 150° or more. It was evaluated as ◯ and less than 150° as ×. The measurement results are shown in Table 1.

Anti-adhesion test The water-repellent laminates for lid materials obtained in Examples and Comparative Examples were tilted at 45° so that the thermal adhesive layer was facing upward, and yogurt (1 g) was dripped onto the thermal adhesive layer. The adhesion of yogurt to the thermal adhesive layer was visually observed and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. Note that Bifidus BB536 Aloe Yogurt manufactured by Morinaga Milk Industry Co., Ltd. was used.
◯: Yogurt did not adhere, and good anti-adhesion properties were exhibited.
△: There was some yogurt adhesion, but there was no practical problem.
×: There was a lot of yogurt adhesion, which caused a practical problem.

Abrasion resistance test The surface of the water-repellent laminate for lid material obtained in Examples and Comparative Examples was rubbed 10 times using a manual tape pressure roll (manufactured by Tester Sangyo Co., Ltd.) (load 2). .5kg). Thereafter, water droplets were dropped on the surface of the thermal adhesive layer, and the slip-off properties were visually observed and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1.
○: Water-repellent fine particles did not slip off, and good water-repellency was exhibited.
△: There was some slipping of the water-repellent fine particles, but water repellency was exhibited without causing any practical problems.
×: Many water-repellent fine particles slipped down, causing a practical problem.

10: Water-repellent laminate for lid material 11: Base material 12: Thermal adhesive layer 13: Water-repellent fine particles 14: Bead particles 20: Container 21: Lid material 22: Container body 23: Opening

Claims (9)

comprising a base material and a thermal adhesive layer on the base material,
The thermal adhesive layer contains a thermoplastic resin, water-repellent fine particles, and bead particles having a larger average particle size than the water-repellent fine particles,
The content of the water-repellent fine particles in the thermal adhesive layer is 5% by mass or more and 85% by mass or less,
The water-repellent fine particles are SiO ₂ subjected to a hydrophobic surface treatment,
The Si element concentration on the surface of the thermal adhesive layer measured by X-ray photoelectron spectroscopy is 17% or more,
The thermal adhesive layer is formed by drying a coating solution containing the thermoplastic resin, the water-repellent fine particles, and the bead particles at a heat amount of 0.5 kJ/m ² or more and 5.5 kJ/m ² or less. A water-repellent laminate for a lid material, characterized in that : The water-repellent laminate for a lid material according to claim 1, wherein the Si element concentration on the surface of the thermal adhesive layer, as measured by X-ray photoelectron spectroscopy, is 20% or more and 50% or less. The laminate according to claim 1 or 2, wherein the water-repellent fine particles have an average particle diameter of 1 nm or more and 300 nm or less. The laminate according to any one of claims 1 to 3, wherein the bead particles have an average particle diameter of 1 μm or more and 50 μm or less. The laminate according to any one of claims 1 to 4, wherein the content ratio of the water-repellent fine particles and the bead particles in the thermal adhesive layer is 10:1 to 1:10 on a mass basis. . The laminate according to any one of claims 1 to 5, wherein the thermal adhesive layer contains a polyester resin and a vinyl chloride-vinyl acetate copolymer. A lid material comprising the laminate according to any one of claims 1 to 6. It comprises the lid material according to claim 7 and a container body,
A container, wherein the thermal adhesive layer of the lid material and the container main body are heat-sealed. A method for manufacturing a laminate according to any one of claims 1 to 6, comprising:
a step of preparing a base material;
A step of applying, on the base material, a coating liquid for a thermal adhesive layer containing a thermoplastic resin, water-repellent fine particles, and bead particles having a larger average particle size than the water-repellent fine particles;
a step of drying the applied coating liquid for the thermal adhesive layer,
A method characterized in that, in the drying step, an amount of heat added to the thermal adhesive layer coating liquid is 0.5 kJ/m ² or more and 5.5 kJ/m ² or less.