JPH10177343A - Light shielding resin container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin container capable of simplifying the structure of a label and reducing distribution and working cost and having an excellent light shielding characteristic. SOLUTION: A resin heat seal layer B containing 25 to 75wt.% carbon black pigment and 75 to 25wt.% resin binder is applied to the rear face of a base sheet A having 30 to 300μm thickness to form a label. A label of which light transmissivity at any of 200 to 800nm wavelength is <=0.5% is stuck to the container so that the resin heat seal layer B is stuck to the outer periphery of the peripheral wall part of the thermoplastic resin made container body. The obtained container has merits having an excellent shielding characteristic against ultraviolet rays and visible light, capable of simplifying the structure of a light shielding label to be used for the container itself and reducing cost and allowed to be easily burnt out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light-shielding resin container useful as a container for milk pudding, yogurt, cheesecake, fresh milk, bavarois and the like.

[0002]

2. Description of the Related Art In foods to which raw milk is added,
The taste of the food deteriorates when it receives ultraviolet visible light [wavelength of 380 to 780 nanometers (nm)] and infrared light. Therefore, as a container for filling these contents, injection molding of polypropylene or high impact polystyrene and differential pressure molding are used. A container having a light-shielding label attached to the outer periphery of the peripheral wall of the obtained resin container is used (see FIG. 1).
As the light-shielding label (2), a polyethylene terephthalate biaxially stretched film or pulp paper (high quality paper) is used as a base material (2a), and an aluminum foil (2b) having a thickness of 4 to 20 μm is bonded to the back surface with an adhesive. Further, a laminate having a heat-sensitive resin film adhesive layer (2c) provided on the surface of the aluminum foil is used (see FIG. 2).

A label (also referred to as a blank) cut into a desired shape is inserted into a container forming mold, and the thermoplastic resin is injection-molded to form an outer periphery of a peripheral wall portion of the container body (1). A light-shielding resin container main body (FIG. 1) covered with a label (2) is formed, or a label is inserted into a differential pressure molding die, and a molten resin sheet is guided onto the die, and a plug assist vacuum is formed. The light-shielding resin container is obtained by molding and / or pressure molding. Japanese Patent Application Laid-Open No. 8-230953 has a problem of incineration of a conventional light-shielding resin container to which a label using such aluminum foil is attached, and proposes the following method as a means for solving the problem. I have.

[0004] A light-shielding layer formed by laminating a light-shielding layer made of an aluminum-deposited biaxially stretched plastic film on the back surface of the substrate, and extruding and coating a heat-sealable resin film on the surface of the light-shielding layer is used. The problem of incineration is solved by reducing the thickness. As shown in FIG. 2, a black ink containing 10 to 20% by weight of a black pigment was solid-printed on a back surface of a base material (2a) such as pulp paper at a plate depth of 35 to 60 μm (2). The problem of incineration is solved by using a light-shielding label obtained by extruding and coating a heat-sensitive resin adhesive (2c) on the base material and making all the label materials flammable.

[0005] The above-mentioned light-shielding labels have a problem in light-shielding properties, and in order to prevent the taste of food containing raw milk from deteriorating, the light transmittance at a wavelength of 200 to 800 nm is 0.5% or less at any wavelength. It is difficult to do. The light-shielding label described above has a thickness of 700 in the embodiment of the publication.
μm thick paper, and the thickness of black solid printing is about 3
5 to 60 μm thick and at least 12 μm thick because the heat-sensitive resin heat seal layer is an extrusion coating
The total thickness is 747 μm or more, which is a thick one, and the number of labels that can be stored in the label magazine stocker for pushing into the whole mold is small, and the bending rigidity of such a thick one is small. It is difficult to form a label having a shape that is high and conforms to the shape of the container body, and the label shape is limited to a rectangular tube. Further, in the manufacture of a light-shielding label, it is necessary to pass through two companies, a printing shop and a laminating shop, and there is a disadvantage that distribution and processing costs increase the cost of the light-shielding label.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a label-attached light-shielding resin container which has a simple label structure, can reduce distribution and processing costs, and has excellent light-shielding properties.

[0007]

According to the present invention, there is provided a method for manufacturing a vehicle, comprising:
On a back surface of the base sheet (A) having a thickness of 00 μm, 25 to 75% by weight of a carbon black pigment, and a resin binder 75
A label (I) provided with a resin heat sealing layer (B) having a thickness of 1 to 5 μm containing
A label having a light transmittance of 0.5% or less at any wavelength in the wavelength range of 00 to 800 nm is formed such that the resin heat seal layer (B) adheres to the outer periphery of the peripheral wall of the thermoplastic resin container body. The present invention provides a light-shielding resin container characterized by being stuck to a resin container.

[0008]

By adding a large amount of carbon black to the resin heat seal layer, excellent light shielding properties can be imparted to the label, and the thickness of the base material and the thickness of the resin heat seal layer can be reduced. Furthermore, when a microporous synthetic paper made of a resin stretched film containing inorganic fine powder is used as the base material, the synthetic paper is oriented so that the light-shielding label can be easily inserted into the mold, And, because of the presence of the inorganic fine powder, the calorie incineration can be reduced, and the light-shielding label pasted on the container body obtained by in-mold molding despite being a stretched film due to heat insulation due to the presence of voids is included. No deformation due to heat shrinkage is observed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a light-shielding label (2) used in the present invention comprises a base sheet (A) as shown in FIG.
The carbon black-containing heat seal layer (B) provided on the back surface.

Base sheet (A): A base sheet having a thickness of 30 to 300 μm which gives a suitable bending rigidity to a label includes pulp paper, pigment coated paper, synthetic paper, polyethylene terephthalate, polycarbonate, polypropylene, Resin films such as density polyethylene and nylon 6, or stretched films thereof, and the like. Preferably, the flexural modulus (JIS P-8132) is 7.0.
00-45,000 kg / cm ² , preferably 10,000
Synthetic paper having a water resistance of 00 to 35,000 kg / cm ² , and a biaxially stretched resin film are used, and particularly preferred are microporous materials made of a stretched thermoplastic resin film containing an inorganic fine powder or an organic filler. Synthetic paper having a porosity of 10 to 50 represented by the following formula:
%, A synthetic paper having a density of 0.600 to 1.20 g / cm ³ and an opacity of 80% or more is preferable.

[0011]

(Equation 2)

Examples of such microporous synthetic paper include the following. Biaxially oriented thermoplastic resin biaxially stretched film containing inorganic fine powder or organic filler at a ratio of 8 to 40% by weight (Japanese Patent Publication No. 54-31032, US Pat. No. 3,775,521, US Pat. No. 4,191,719) No., U.S. Pat. No. 4,377,616, U.S. Pat. No. 4,560,614). Synthetic paper using a biaxially stretched thermoplastic film as a base layer and a uniaxially stretched thermoplastic resin film containing from 8 to 65% by weight of inorganic fine powder as a paper-like layer (JP-B-46-4079).
No. 4, JP-A-57-149363, and JP-A-57-149363.
No. 181829).

The synthetic paper may have a two-layer structure or a three-layer structure in which a paper-like layer of a uniaxially stretched film is present on the front and back surfaces of the base material layer (Japanese Patent Publication No. 46-40794). 3 layers in which another resin film layer exists between the paper-like layer and the substrate layer
Even in the case of a seven-layer synthetic paper (JP-B-50-29738, JP-A-57-149363, JP-A-56-126155 and JP-A-57-181829), the back surface is a propylene / ethylene copolymer. , Metal salts of ethylene / (meth) acrylic acid copolymer (Na, Li, Zn, K),
It may be three or more layers of synthetic paper having a heat seal layer made of a resin having a body melting point higher than that of a base layer resin such as chlorinated polyethylene (Japanese Patent Publication No. 3-13973).

A method for producing a three-layer synthetic paper is, for example, as follows.
A thermoplastic resin film containing 0 to 50% by weight of an inorganic fine powder is uniaxially stretched at a temperature lower than the melting point of the resin and uniaxially oriented. Wt% of a thermoplastic resin-containing molten film is laminated, and then the laminated film is stretched in a direction perpendicular to the above-mentioned direction. A paper-like layer obtained is oriented uniaxially, and is a film having many fine voids. In some cases, the base material layer is a laminated structure oriented biaxially.

[0015] On the paper-like layer side of the synthetic paper,
Synthetic paper capable of high gloss printing with a structure provided with a transparent thermoplastic resin laminate layer having a thickness of 0.1 to 20 μm containing no inorganic fine powder (Japanese Patent Publication Nos. 4-60437 and 1-60411) For example, a surface layer composed of a uniaxially stretched thermoplastic resin film containing 8-65% by weight of an inorganic fine powder using a biaxially stretched film of a thermoplastic resin as a base layer. A composite film having a composite film having a back layer and a back layer, a transparent film layer of a thermoplastic resin containing no inorganic fine powder is provided on the surface layer side of the support, and a primer coating amount having an antistatic function is further provided. Paper (Japanese Unexamined Patent Publication No. Sho 61-3748) or a biaxially stretched thermoplastic resin film is used as a base layer, and at least one surface of the base layer is coated with an inorganic fine powder of 8-65. A synthetic paper provided with a laminate of a paper-like layer made of a uniaxially stretched film of a thermoplastic resin and a back layer made of a uniaxially stretched film of a thermoplastic resin film, wherein The thickness (t) of the layer is defined by the following formula (2) when the average particle size of the inorganic fine powder present in the paper-like layer is represented by (R). Paper (Tokuhei 1
60411).

R.gtoreq.t.gtoreq. (1/10) R (2) The synthetic paper having the multi-layer structure may have a heat seal layer provided on the front and back surfaces similarly to the synthetic paper. Specific examples of the thermoplastic resin as a material of the synthetic paper include polypropylene, and a density of 0.880 to 0.965 g / cm ^3.
Polyethylene, polystyrene, polyacrylonitrile, polyvinyl chloride, polyethylene terephthalate, polyamide, polycarbonate and the like. Among these thermoplastic resins, especially polypropylene,
Preferably, high density polyethylene is used.

Examples of the inorganic fine powder include fillers having a particle size of 0.1 to 5 μm, such as calcium carbonate, clay, silica, talc, mica, titanium oxide, barium oxide and zinc oxide. The stretching ratio is preferably 4 to 10 times in both the longitudinal and transverse directions. The stretching temperature is 140 to 162 ° C when the resin is homopolypropylene (melting point 164 to 167 ° C), and when the resin is high density polyethylene (melting point 121 to 124 ° C). 11
0 to 120 ° C, polyethylene terephthalate (melting point 24
6 to 252 ° C.). The stretching speed is 50 to 350 m / min. Stretching forms fine holes inside the film with the fine powder as a nucleus.

On the surface of the substrate, the product pattern, product name, and the like are printed by gravure printing, offset printing, silk screen printing, etc.
A barcode, a manufacturer, and the like may be printed. The opacity of such microporous synthetic paper is preferably 80 to 100%. The Clark stiffness (S value) is 10-30 in the longitudinal direction.
0 and 25 to 400 in the horizontal direction are preferable in terms of facilitating insertion of the light-shielding label into the mold.

Resin heat seal layer (B) The resin heat seal layer (B) is made of 25% carbon black.
-75% by weight, preferably 40-65% by weight, and 75-25% by weight, preferably 60-3% by weight of the resin binder.
5% by weight of a black heat-seal layer having a thickness of 1 to 5 μm. To form such a thin heat seal layer, a resin binder is dissolved or a particle size of 0.01 to 5 μm.
m, preferably 0.1 to 3 μm.
A resin solution in which Bon Black and a resin binder are dispersed or dissolved is applied using a roll coater, a brush, a blade, or the like so that a film having a thickness of 1 to 5 μm is formed on the back surface of the base sheet (A). , And dried.

Examples of the carbon black include Ketjen black, furnace black, channel black, and acetylene black. Ketjen black and furnace black having the highest possible oil absorption are preferred. Resin binders include curable urethane resins such as reactive polyester polyols / polyisocyanates, polyether polyols / polyisocyanates; low density polyethylene, linear low density polyethylene, ethylene
Vinyl acetate copolymer, ethylene / acrylic acid copolymer (preferably ethylene / acrylic acid copolymer having an ethylene content of 65 to 94% by weight), ethylene / methacrylic acid alkyl ester copolymer, ionomer (ethylene / acrylic acid Metal salt of copolymer, or metal salt of ethylene / methacrylic acid copolymer), vinyl chloride / vinyl acetate copolymer, styrene / maleic acid copolymer, styrene
Softening point of ethylene / maleic acid copolymer, butyl acrylate / styrene / acrylic acid copolymer, aliphatic polyester, aliphatic polyamide, aromatic polyamide etc. is 60 ~
A thermoplastic resin at 120 ° C., preferably 70 to 110 ° C., may be used.

As the solvent, water, toluene, xylene,
Mineral split, methyl ethyl ketone, acetone,
Examples include methanol, ethanol, and isopropyl alcohol. The solvent has a solid content concentration of 6 to 6 in the resin solution.
The amount used is 0% by weight. Carbon black,
In the dispersion of the resin binder in the solvent, a surfactant,
You may mix | blend an antifoaming agent, a viscosity modifier, etc. The light-shielding label of the present invention has a light transmittance at a wavelength of 200 to 800 nm of 0.5% or less at any of these wavelengths.
Preferably it is 0.2% or less, more preferably 0.1% or less.

Container body: The container body is made of polypropylene,
Injection molding, hollow molding, differential pressure molding (vacuum molding, air pressure molding) of thermoplastic resins such as polystyrene, high-impact polystyrene, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, nylon 6, nylon 66, etc., having melting points of 150 ° C. or higher. Is obtained by The thickness of the container body is 0.1 to 2 mm, preferably 0.1 mm.
3 to 1 mm. The in-mold molded light-shielding label is placed in a mold, and the surface of the heat seal layer is partially melted by the above-described injection molding, hollow molding, differential pressure molding, etc., and the light is shielded on the container body (1) as shown in FIG. A light-shielding resin container to which the hydrophilic label (2) is fused is obtained. In the figure,
(3) is a flange.

Food Packaging A food is filled in the light-shielding resin container of the present invention, and the opening of the container body is heat-sealed with a light-shielding lid for packaging. As the lid material, a material in which a heat seal resin layer is provided on an aluminum foil is suitably used.

[0024]

The present invention will be described more specifically with reference to the following examples. Production of synthetic paper Example Example 1 (1) Melt shift over rate (MFR) of the 0.8 g / 10 min Polypropylene (melting point: about 164 to 167 ° C.) 81% by weight, high density polyethylene 3% by weight and average particle diameter 1.5
The composition (A) containing 16% by weight of calcium carbonate of 16 μm was kneaded with an extruder set at a temperature of 270 ° C., extruded into a sheet, and further cooled to 60 ° C. by a cooling device.
To obtain a non-stretched sheet. And
After heating this sheet again to a temperature of 150 ° C.
The film was stretched 5 times in the machine direction to obtain a 5 times stretched film.

(2) A composition in which 54% by weight of polypropylene (melting point: about 164 to 167 ° C.) having an MFR of 4 g / 10 minutes, 43% by weight of calcium carbonate having an average particle size of 1.5 μm, and 3% by weight of titanium oxide are mixed. After kneading the product (B) with another extruder, this was extruded into a sheet by a die,
After cooling to a temperature of 0 ° C., this was laminated with the 5 × longitudinally stretched film obtained in the above step (1),
6. Heat to a temperature of ° C and use a tenter to move in the lateral direction.
Stretched 5 times, annealed at a temperature of 153 ° C,
After cooling to a temperature of 60 ° C. and performing corona discharge treatment, the ears were slit, and the three-layered structure of a uniaxially stretched film (B) / biaxially stretched film (A) / uniaxially stretched film (B) was used. 80 μm thick (B / A / B = 20 μm / 40 μm /
20 μm), porosity 33%, density 0.77 g / cm ³ ,
Opacity 92%, Clark stiffness (vertical direction 20, horizontal direction 3
8) A synthetic paper was obtained.

Gravure printing is performed on the surface B of the synthetic paper,
The product design, product name, and manufacturer are printed. Example 2 (1) 81% by weight of polypropylene (melting point about 164 ° C.) having an MFR of 0.8 g / 10 minutes, 3% by weight of high-density polyethylene and 16% by weight of calcium carbonate having an average particle size of 1.5 μm
Was kneaded by an extruder set at 270 ° C., extruded into a sheet, and cooled by a cooling device to obtain a non-stretched sheet. And this sheet is 1
After heating again to a temperature of 40 ° C., the film was stretched 5 times in the machine direction to obtain a 5 times machine stretched film.

(2) A composition (B) comprising a mixture of 54% by weight of polypropylene having an MFR of 2.0 g / 10 min and 46% by weight of calcium carbonate having an average particle size of 1.5 μm, and an MFR of 4.0 g / 10 (C) obtained by mixing 80% by weight of polypropylene with 10% by weight of high-density polyethylene and 10% by weight of calcium carbonate having an average particle size of 1.5 in a separate extruder, and then mixing the resulting mixture with a die. And then laminated on both sides of the 5-fold longitudinally stretched film of (1) above to obtain a three-layer laminated film (layer B / layer A / C).
Layer). Then, this three-layer laminated film was
After cooling to 0 ° C, it was heated again to a temperature of about 160 ° C and stretched 7.5 times in the transverse direction using a tenter.
After annealing at a temperature of 5 ° C., cooling to a temperature of 60 ° C., and performing corona discharge treatment, the ears are slit and the wall thickness of a three-layer structure (uniaxial stretching / biaxial stretching / uniaxial stretching) 90
μm (B / A / C = 15 μm / 60 μm / 15 μm) was obtained. The void ratio of each layer of the synthetic paper is (B / A
/C=30%/29.7%/2.0%) and a density of 0.8
It was 0 g / cm ³ , opacity 90%, and Clark stiffness (length 16 and width 33). Gravure printing was performed on layer B of this synthetic paper.

Formation of heat seal layer containing carbon black
Preparation Examples Examples of use coating liquid 3 by Toyo Morton Co., Ltd. heat-sealing material "Adcoat 15
36AD "(trade name: polyester polyol / polyisocyanate resin 15 parts by weight dissolved in 85 parts by weight of toluene) 400 parts by weight of furnace black 1
5% by weight, toluene 30% by weight, methyl ethyl ketone 5
600 parts by weight of a dispersion composed of 0% by weight and 5% by weight of isopropyl alcohol were mixed and kneaded with a three-roll mill to form a uniform dispersion.

Example 4 Heat sealant "Adcoat 33" manufactured by Toyo Morton Co., Ltd.
0P "(trade name; 40% by weight toluene solution of ethylene / vinyl acetate copolymer having a softening point of 108 ° C) 200
15 parts by weight of furnace black, 5 parts by weight of toluene
800 parts by weight of a dispersion composed of 0% by weight and 35% by weight of methyl ethyl ketone were mixed and kneaded with a three-roll mill to obtain a uniform dispersion.

(Example 1) On the unprinted surface of the synthetic paper having a thickness of 80 µm obtained in Example 1, the color paper obtained in Example 3 was placed.
Using a gravure printing roll, a uniform dispersion containing Bon Black and a resin binder was applied so as to obtain a heat seal layer having a thickness of 1.5 μm, and dried at 60 to 80 ° C. to obtain a light-shielding label. The light-shielding label was measured with an ultraviolet / visible light photometer UBEST-30 manufactured by JASCO Corporation at a wavelength of 200 to 340 nm in the ultraviolet region and a wavelength of 340 to 340 in the visible light range.
780, when the light transmittance at a wavelength of 780 to 1,000 nm in the infrared region was measured, the maximum transmittance was 0.4% at 200 nm wavelength in the ultraviolet region, 0.2% at 425 nm in the visible light region, 0 in the infrared region.
It was 0%.

FIG. 4 is a plot showing the light transmittance at each wavelength emitted by a computer every 5 nm.
This light-shielding label was cut, inserted into an injection mold, and injection-molded at 200 ° C. with high-impact polystyrene (Styrol IT41, manufactured by Idemitsu Petrochemical Co., Ltd.), and a melt flow rate of 4 g / 10 minutes manufactured by Mitsubishi Chemical Corporation. Polypropylene "Mitsubishi Polypropylene MA-4" (trade name) 24
Injection molding was performed at 0 ° C. to obtain a light-shielding resin container having a light-shielding label having a thickness of 0.6 mm and having a light-shielding label attached to the entire peripheral wall of the container body.

The adhesion strength between the label and the container body is HIPS.
The container had a width of 500 g / 15 mm or more, and the polypropylene container had a width of 350 g / 15 mm. Table 1 shows the above results. (Examples 2 to 5, Comparative Examples 1 to 4) Curing of heat seal layer
A light-shielding label was produced in the same manner as in Example 1 except that the amount of the bon black and the kind of the resin binder were changed as shown in Table 1, and then a light-shielding resin container was produced by in-mold molding. Table 1 shows the obtained results.

Example 6 In Example 1, the coating amount of the carbon black-containing resin binder uniform dispersion was 3 μm.
A light-shielding label was manufactured in the same manner except that the film (heat-seal layer) of m was obtained, and a light-shielding resin container was manufactured by in-mold molding using the same. Table 1 shows the obtained results.

Example 7 15% by weight of a styrene / ethylene / maleic anhydride copolymer having a softening point of 90 ° C. and a polyether polyol were placed on the unprinted back side (C) of the synthetic paper obtained in Example 2. A 3.5 μm-thick heat seal of a uniform dispersion comprising 8% by weight of polyisocyanate, 23% by weight of channel black, 28% by weight of toluene, 20% by weight of methyl ethyl ketone, 5% by weight of isopropyl alcohol, and 1% by weight of a surfactant. The layer was coated to obtain a layer, and dried at 80 ° C. to produce a light-shielding label. (Maximum light transmittance: 0.3% of ultraviolet region, 0.1% of visible light region, 0.1% of infrared region) A light-shielding resin container is obtained in the same manner as in Example 1 except that this light-shielding label is used. Was. The adhesive strength of the light-shielding label to the container body was 500 g / 15 mm for a HIPS container.
It was 340 g / 15 mm wide in a polypropylene container over the width.

[0035]

[Table 1]

[0036]

The light-shielding resin container of the present invention has an advantage that it is excellent in the shielding property of ultraviolet rays and visible light, and the structure of the light-shielding label used therein is simple, the cost is low, and the incineration property is excellent. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a light-shielding resin container according to the present invention.

FIG. 2 is a cross-sectional view of a conventional light shielding label.

FIG. 3 is a cross-sectional view of a light-shielding label used in the embodiment of the present invention.

FIG. 4 is a graph showing light transmittance at each wavelength of a light-shielding label used in Example 1.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Isao Kawashima 3-5-3 Misakicho, Chiyoda-ku, Tokyo Showa Printing Co., Ltd.

Claims (3)

[Claims] 1. A resin having a thickness of 1 to 5 μm, comprising 25 to 75% by weight of a carbon black pigment and 75 to 25% by weight of a resin binder on the back surface of a base sheet (A) having a thickness of 30 to 300 μm. The label (I) provided with the heat seal layer (B), the label having a light transmittance of 0.5% or less at any wavelength in the wavelength range of 200 to 800 nm is the label of the thermoplastic resin container body. A light-shielding resin container, wherein the resin heat seal layer (B) is adhered to the outer periphery of the peripheral wall so as to adhere to the container body. 2. The base sheet (A) is a microporous synthetic paper made of a stretched thermoplastic resin film containing an inorganic fine powder or an organic filler, represented by the following formula: The light-shielding resin container according to claim 1, wherein synthetic paper having a porosity of 10 to 50% is used. (Equation 1) 3. The light-shielding resin container according to claim 1, wherein the resin binder of the resin heat sealing layer (B) is a resin having a softening point of 60 to 120 ° C. or a curable polyurethane.