JP3514867B2 - In-mold label - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention sets a label so that the front side of the label printed in advance in the mold is in contact with the wall surface of the mold, and the molten thermoplastic resin is set in the mold. The present invention relates to a label used for in-mold molding for producing a label-bonded container by hollow molding of a parison or vacuum molding or pressure molding of a molten thermoplastic resin sheet.

In particular, the transparent or translucent label for in-mold molding of the present invention is capable of visually recognizing the amount of the contents of the container to which it is attached, or the colors of the container and the label are harmonious (as if the label is a container. It is possible to provide a label-bonded container that gives the buyer a visual sense as if the label-bonded container was not bonded to. This label-bonded container is useful as a container for shampoo, rinse, motor oil, carbonated drink, hair dressing, fancy food and the like.

[0003]

2. Description of the Related Art Conventionally, in order to integrally mold a resin molded container with a label, a blank or a label is previously inserted into a mold, and then the container is formed by injection molding, hollow molding, differential pressure molding, foam molding or the like. Then, the container is painted (so-called in-mold molding). Since water resistance is required for such a label, offset multicolor printed synthetic paper (for example, Japanese Patent Publication No. 46-40794,
Japanese Patent Publication No. 54-31030, British Patent No. 10900
No. 59 etc.) or an aluminum label in which polyethylene is laminated on the back surface of an aluminum foil and gravure-printed on the surface of the foil (Japanese Patent Publication No. 3-28315, Japanese Patent Publication No. 2-7814). , JP-A-60-21244, JP-A-2-30513).

However, in the method for producing a label-bonded container decorated with a label by in-mold molding using the above-mentioned in-mold label or blank, a high pressure (100 to 1000 kg / cm ² ) like injection molding is used. Although a product with a good appearance can be obtained by the method of fusing the blank and the molten resin container, differential pressure molding ( ^{2 to} 7 kg / cm ² )
In the low-pressure molding method such as or hollow molding (1 to 10 kg / cm ² ), the escape of air between the blank and the melting container was not sufficient, and small air bubbles were enclosed in places between the container and the blank. Blistering occurs and only a container with a poor appearance can be obtained.

As a means for solving this, a method has been proposed and implemented in which polyethylene, which is the heat-sealing layer of the label, is provided with an embossed pattern to facilitate air escape between the container and the label during in-mold molding. (Japanese Utility Model Publication No. 5-22947, Japanese Patent Laid-Open Nos. 1-310931, 2-84319, and 3-260689).

[0006] For example, in Japanese Utility Model Publication No. 5-22947, a heat-sealable resin layer having a melting point lower than the melting point of the material resin of the film is formed on the back surface of a thermoplastic resin film substrate layer having a printed surface. The heat-sealable resin layer is embossed with 5 to 25 lines per 2.54 cm, and the depth of the valley of this embossing is 4 to 8 μm.
A label for in-mold molding which is (micron) and is embossed with a thickness of 1/3 or more of the thickness of the heat-sealable resin layer is disclosed.

As a thermoplastic resin film base layer, a polypropylene film containing 8 to 65% by weight of an inorganic filler is stretched as described in JP-A-46-40794. The opaque synthetic paper and the opaque high-gloss synthetic paper “YUPO” GPG (trade name) manufactured by Oji Yuka Synthetic Paper Co., Ltd. are used. The opacity (JIS P-8138) of these synthetic papers is as high as 85% or more, and it is difficult to visually check the amount of the content of the laminated container from this label. Further, it is difficult to match the color of the label with the color of the container to be molded.

[0008]

In order to solve the above problems, a transparent label using a transparent biaxially oriented polypropylene film (BOPP) as a base material layer of the label described in Japanese Utility Model Publication No. 5-22947 is used. When using the in-mold hollow molding, the label was not smoothly inserted using the label inserter that automatically inserts the label into the mold, and the label was stuck to 76 of 100 hollow containers. I found something not. In addition, the BOPP has a drawback that printing is limited to gravure printing and multicolor printing such as offset printing and screen printing cannot be performed.

According to the present invention, not only gravure printing but also offset printing and screen printing are possible, and the label inserter can be used to smoothly insert the label into the mold. It is intended to provide a transparent or translucent label for in-mold molding.

[0010]

The present invention has a melting point of 140.
A biaxially stretched film of a thermoplastic resin having a temperature of ℃ or more is used as a base material layer (A), a primer layer (B) is provided on the front surface side, and a primer layer (C) is provided on the back surface side of the base material layer.
Further, the surface of the primer layer (C) is provided with a thermosensitive resin adhesive layer (D), the surface of the thermosensitive resin adhesive layer (D) is embossed, and the primer layer (B) is provided.
Either one of the primer layers (C) or both of the layers are combined with an anti-blocking agent in an amount of 0.1 to 3% by weight, and the primer layer (B) of a laminated film having an opacity of 20% or less is printed. The label for in-mold molding is provided.

[0011]

Since it is a transparent or translucent label, the amount of the contents of the laminated container can be seen through from the label side. Further, since the background color of the container enters the visual field through the label, there is no mismatch between the label color and the container color. By providing the primer layer (B), offset printing, screen printing, and sticker printing were also possible. Further, since the anti-blocking agent is blended in the primer layer (B) or (C) or both layers, it is possible to smoothly feed the laminated film (B / A / C) before providing the heat-sensitive adhesive layer. In addition, the heat-sensitive adhesive layer (D) of the label on the side to be bonded to the molded container is embossed, and the label side on the side in contact with this is the primer layer (B). Blocking of each other is prevented, and automatic label supply by the label inserter is smoothly performed.

Further, due to the presence of the primer layer (C),
Since the adhesive strength between the heat-sensitive adhesive layer (D) and the base material layer (A) is strong, even if the label is manually peeled off from the laminating container, the biaxially stretched film (A) is not delaminated. , The label is not peeled from the container. (Outline of the Invention) FIG. 1 is a sectional view of the label for in-mold molding of the present invention. In the figure, 1 is a transparent or translucent label, A is a transparent biaxially stretched film, B is a primer layer, 2 is printing, C is a primer layer, D is a heat-sensitive adhesive layer (heat seal layer), and 3 is embossed. The processed peaks 4 indicate the embossed valleys.

The label 1 has a wall thickness of 20 to 300 μm, preferably 40 to 120 μm, the biaxially stretched film A has a wall thickness of 15 to 250 μm, preferably 30 to 100 μm, and the primer layers B and C have a wall thickness of 0. 5 to 5 μm, preferably 1 to 3 μm, the heat-sensitive adhesive layer D is 3 to 40 μm, preferably 3 to 30 μm when it is a coating type adhesive, and 12 to 40 μm when it is a hot melt type adhesive. .

[0014] substrate layer (A) a biaxially oriented film thermoplastic resin base material layer (A) has a melting point of 140 ° C. or more, preferably of 160 to 300 ° C., propylene homopolymer, propylene Ethylene copolymer, propylene / ethylene / butene-1 copolymer, propylene / butene-1 copolymer, propylene / 4
-Propylene resins such as methyl pentene-1 copolymer and propylene-3-methyl pentene-1 copolymer; polyolefins such as poly (4-methyl pentene-1) and poly (butene-1); nylon 6, nylon 6, Polyamide such as nylon 6,6; Polyester such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate,
Examples include engineering plastics such as polyphenylene sulfide and polyphenylene ether.

Above all, from the market, surface smoothness (JIS
P-8119) is a biaxially stretched film (BOPP) of a propylene homopolymer having a molecular weight of 15,000 to 45,000 seconds,
Biaxially oriented polyethylene terephthalate film (BOP
ET) is preferable because it can be obtained at a lower cost than stretched films of other resins. The stretching ratio of the biaxially stretched film is 4
10 to 10 times and 4 to 20 times in width. Also, the wall thickness is 20-25
0 μm, preferably 40 to 120 μm is preferable in terms of economy and label insertability. Generally, opacity of these biaxially stretched films is 10% or less, and 0.1 to 5% is easily available.

Primers (B) and (C) As primers that contribute to improving the adhesion of printing inks and improving the adhesive strength between the base material layer (A) and the heat-sensitive adhesive layer (heat seal layer; (D)). , Urethane polyols of polyether polyol / polyisocyanate, polyester polyol / polyisocyanate, titanate primers, polyethyleneimine, poly (ethylene-urea), ethyleneimine adduct of polyamine polyamide,
An epichlorohydrin adduct of polyamine polyamide and a tertiary to quaternary nitrogen-containing acrylic resin are used. These are diluted with an organic solvent such as water, alcohol, acetone, toluene or methyl ethyl ketone before use.

The coating amount of the primer is 0.5 in terms of solid content.
-5 g / m < ² >, preferably 2-8 g / m < ² >.
Primer layer (B) and / or primer layer (C)
On the side, an anti-blocking agent is added in an amount of 0.1 to 3% by weight in order to facilitate the paper feeding / discharging property (feeding by a roll) of the laminated film (B / A / C) before the heat-sensitive adhesive layer (D) is provided. %,
Preferably, it is blended in an amount of 0.3 to 1% by weight.

The composition of the anti-blocking agent in the primer layer (B) is further prevented from blocking the labels due to the embossed pattern of the heat-sensitive adhesive layer (D) and the additive effect of the anti-blocking agent in the primer layer (B). The printing workability is also excellent, and the label inserter automatically completes the automatic supply of labels into the mold.

Anti-blocking agent As the anti-blocking agent, an inorganic anti-blocking agent having a particle size of 0.01 to 2 μm such as silicon oxide or talc, an organic anti-blocking agent such as poly-silicone oil or poly (tetrafluoroethylene) Agents are used. If the content of the anti-blocking agent in the primer layer (B) or (C) is less than 0.1% by weight, blocking with the feed roll is likely to occur and the blocking cannot be performed smoothly. If it exceeds 3% by weight, the transparency of the label is lowered, which is not preferable.

Examples of the hot-melt (hot melt extrusion type) resin forming the heat-sensitive adhesive layer (D) the heat-sensitive adhesive layer (D), low density polyethylene, vinyl ethylene acetate copolymer, ethylene-acrylic acid copolymer ,
Metal salts of ethylene / methacrylic acid copolymer, ethylene /
Melting point of methyl acrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / butyl acrylate copolymer, ethylene / methyl methacrylate copolymer, etc. is 70
A heat-sealable resin having a temperature of up to 135 ° C can be used.

As the coating type heat-sensitive adhesive, ethylene (ethylene content of 20 to 40 mol%, vinyl acetate copolymer (aqueous or oily) emulsion, ethylene (10
.About.35 mol%). Acrylic acid copolymer emulsion and the like, which are applied to the primer layer (C) and then dried to disperse the solvent (water, alcohol, acetone, toluene, methyl ethyl ketone, etc.). A heat sensitive adhesive layer is formed.

Further, as a heat-sensitive adhesive, a heat-sensitive adhesive which is used in a delate label and does not exhibit tackiness at room temperature (10 to 30 ° C.) (Japanese Patent Publication No. 5-18433 / JP-A 1-222290). Gazette, the same 4-72125
No. 5-32241, No. 6-27881, No. 6-100847, No. 6-100848.
(See Japanese Patent Publication) may be used.

Such heat-sensitive adhesives include (a) polyvinyl acetate, n-butyl acrylate / styrene copolymer, vinyl oxide-vinylidene chloride copolymer, natural rubber, and acetic acid, as shown in the above-mentioned publications. Vinyl-acrylic acid 2-ethylhexyl copolymer, vinyl acetate-ethylene copolymer,
Polymer resins having a glass transition point of 20 ° C. or less, such as bilpyrrolidone-styrene copolymer, styrene-butadiene rubber, butyl rubber, vinylpyrrolidone-ethyl acrylate copolymer, and (b) diphenyl phthalate, phthalic acid Dihexyl, dicyclohexyl phthalate, bihydroabietyl phthalate, dimethyl isophthalate, sucrose benzoate, ethylene glycol dibenzoate, trimethylolethane tribenzoate, tribenzotriglyceride triglyceride, pentaerythritol tetrabenzoate, sucrose octaacetate. Of a plasticizer solid at room temperature such as tricyclohexyl citrate, N-cyclohexyl-p-trienesulfonamide, and (c) a rosin derivative (rosin, polymerized rosin, hydrogenated rosin and their glycerin, pentaerythritol, etc. ester,
The resin acid dimer, etc.) contains a tackifier such as a terpene resin system, a petroleum resin system, a phenol resin system, a xylene resin system, etc., and does not exhibit adhesiveness at room temperature (10 to 25 ° C.). It exhibits activity by heating (75 to 140 ° C.) and exhibits tackiness for a while (5 seconds to 2 weeks) even if heating is stopped.

If desired, an antioxidant, colloidal silica, alumina sol, etc. may be added. The coating amount of the heat-sensitive adhesive applied on the primer (C) is 3 to 30.
It is in the range of g / m ² (solid content).

Embossing The heat-sensitive adhesive layer (D) of the laminated film of B / A / C / D layers is embossed as shown in JP-B-5-22947 and JP-A-5-149895, and the label is attached. Prevents the formation of air pockets between the and resin molding containers. This label has an embossed pattern with 5 to 25 dots or lines per 2.54 cm (1 inch), preferably 15 to 2
The number is set to 0. The number of dots (dots) or lines per 2.54 cm is called the number of lines, and is a measure of the fineness of the embossed pattern. If the number of lines is outside the range of 5 to 25 lines,
Air bubbles are liable to occur between the label and the resin molded product, which causes a prister. The pattern may be a hemisphere or a cylinder, and may be a square prism or a trapezoidal prism.

The depth of the valley of the embossed pattern is 4 to 8 μm, and is 1/3 or more, preferably 1/2 or more of the thickness of the heat-sensitive adhesive layer (D), and the base layer (A). It may be difficult to get inside. If the depth of this valley is shallow, air will not escape easily between the label and the parison or the sheet during blow molding or differential pressure molding, and this will cause the occurrence of pristers. Also, if it is too deep, air will be trapped, which will cause the occurrence of pristers. Embossing is performed with a metal roll and a rubber roll.

Opacity of the laminated film having a laminated structure of laminated film B / A / C / embossed D is 20% or less, preferably 5 to 15%.
And the laminated film is transparent or translucent. or,
Glossiness of the primer layer (B) (JIS P-8142;
The measurement (60 °) shows about 10 to 40% depending on the kind of the anti-blocking agent used. Surface smoothness (JIS P-
8119) is 75 on the printed primer layer (B) side.
0 to 1500 seconds, the embossed heat-sensitive adhesive layer (D) is 1
It is 5 to 250 seconds, preferably 15 to 100 seconds, and it is understood from this value that the escape of air between the molded container and the label is easily performed.

The printing on the printing primer layer (B) is carried out by printing such as gravure printing, offset printing, flexo printing, screen printing, sticker printing, and the like, and the bar code, manufacturer, sales company name, character, product name. Print usage, scale, etc. The printed and embossed label is punched to be separated into a label having a required shape and size. The label for in-mold molding may be a partial one that is attached to a part of the surface of the container, but it is usually used as a blank surrounding the side surface of the cup-shaped container, and in the case of hollow molding, it is a bottle-shaped container. It is manufactured as a label attached to the front and back.

In-Mold Molding In this in-mold molding label, the label is placed in the cavity of the lower female mold of the differential pressure molding mold so that the print side of the label is in contact with the cavity surface of the mold, and then the mold is sucked. It is fixed to the inner wall of the mold by means of, and then the melt of the resin sheet of the container molding material is guided to the upper part of the lower female mold and pressure-differential molded by a conventional method, and the label is integrally fused to the outer wall of the container. The combined container is molded.

As the differential pressure forming, either vacuum forming or pressure forming can be adopted, but in general, both are used together and the differential pressure forming utilizing plug assist is preferable. This label can also be applied to hollow molding in which a molten resin parison is pressure-bonded to the inner wall of the mold. Examples of the resin forming the container include high-density polyethylene, branched low-density polyethylene, linear polyethylene, polypropylene, nylon 6, nylon 6,6, polyethylene terephthalate polycarbonate, polyphenylene oxide, polyphenylene ether, and ethylene / vinyl acetate copolymer. Can be mentioned.

In the label-bonded container thus manufactured, the label and the resin container are integrally molded after the label is fixed in the mold, so that there is no deformation of the label and the container body and the label are in close contact with each other. It is a strong container, has no blister, and has a good appearance decorated with a label.
Further, since the label is transparent or translucent, the color of the container can be seen through the label, so that the color of the label and the container can be visually recognized as if they were one. Further, the contents of the container, for example, drinking water, liquid medicine, waterline of shampoo, etc. can be visually observed.

[0032]

【Example】

(Example 1) Biaxially oriented polypropylene film A having a thickness of 80 μm (melting point 176 ° C., opacity 0.8%, surface smoothness 24,000 seconds) manufactured by Nimura Sansho Co., Ltd. 0.5 wt% of 1 μm silicon oxide powder and urethane-based primer “Pinacia CVL-SP” (trade name) manufactured by Dainippon Ink and Chemicals, Inc. each had a solid content of 1 g / m 2.
Apply using a gravure ink roll so that it becomes ² ,
Dried (B), (C).

Then, a solvent type ethylene-vinyl acetate copolymer "Adcoat 1790" (trade name) manufactured by Toyo Morton Co., Ltd. is applied to the surface of the primer layer (C) on the back side and heated at 80 ° C. And the solvent was scattered to form a heat-sensitive adhesive layer D (melting point: 78 ° C.) having a thickness of 4 μm. This laminated film is passed through an embossing roll and spaced by 1.27 mm (20
Lines) and dots having a valley depth of 4 μm were formed on the heat-sensitive adhesive layer side.

The label laminated film thus obtained had a thickness of 87.8 μm and a density of 0.892 g / cm ³ .
Opacity 12.2%, glossiness (surface side 18.8%, embossing side 37.3%), surface smoothness (surface side 1.145)
Second, 67 seconds on the embossing side). Four-color offset printing was applied to the primer layer on the surface side of this embossed laminated film, and then this was punched to obtain a hollow molding label (width 60 mm, length 110 mm).

A label inserter manufactured by Pentel Co., Ltd. is used so that the printing surface is brought into contact with the mold (temperature of 30 ° C.) by using a vacuum for one of the molds for blow molding using a blow molding machine manufactured by Placo. After fixing with, the high-density polyethylene (melting point: 134 ° C) parison containing 3% by weight of a yellow pigment was melt extruded at 210 ° C, and then the split mold was clamped, and then 4.2 kg / cm ² of compressed air was applied to the parison. Supply within
The parison was expanded to form a container and fused with the label, then the mold was cooled and the mold was opened to obtain a label-bonded flat hollow container.

The label-bonded flat hollow container had no discoloration in printing, and neither label shrinkage nor blister or orange peel was observed. Also, the adhesive strength (JIS P-8113) between the label and the flat hollow container is 411 g / 15.
The width was mm. Of the 10,000 hollow containers, the number of non-labeled containers was zero.

Example 2 Using the in-mold molding label obtained in Example 1 and a molding machine, 3% by weight of a yellow pigment was used.
2 parison of propylene / ethylene block copolymer (melting point 174 ° C) containing MFR of 1.2 g / 100,000
Melt extrusion was carried out at 20 ° C., and a round hollow container was obtained in the same manner. The label-bonded yellow round container did not suffer from color fading in printing, and neither label shrinkage nor blister or orange peel was observed.

The adhesive strength between the label and the container is 342 g / 15.
The width was mm. In addition, the number of hollow containers formed with 10,000 pieces was one without the label attached. In addition, the hue measured from the label of the label-bonded container (JIS L-101
5) is L value 92.1, a value −9.1, b value (yellowness) +
It was 47.1 and the opacity was 77.5% (by the way, the opacity of the container of Example 1 of JP-B-5-22947 is 97%). Further, the hue of the yellow hollow container obtained without sticking the label has an L value of 92.4 and an a value of -10.
7, b value +51.1, and opacity was 73.9%.

Example 3 In the same manner as in Example 1, except that the surface-side primer layer (B) was not blended with silicon oxide powder as an anti-blocking agent, the thickness was 88.1 μm and the density was 0.890 g / cm ³ , Laminated sheet (B / A / C / D) with opacity of 11.5%, glossiness (20% on surface side, 37.6% on embossing side), surface smoothness (1022 seconds on surface side, 70 seconds on embossing side) Obtained.

Thereafter, printing, punching and blow molding were carried out in the same manner as described above to obtain a label-bonded container free from heat discoloration of the label, occurrence of blisters, and orange peel without causing discoloration of the print. The adhesive strength between the label and the container was 333 g / 15 mm width. In addition, a hollow container made of yellow high-density polyethylene was found in which 16 of the 10,000 hollow containers were not labeled.

(Example 4) Yellow propylene-labeled in the same manner as in Example 2 except that a label containing no anti-blocking agent in the primer layer (B) obtained in Example 3 was used as the label. An ethylene block copolymer hollow container was obtained. This product had no color fading, heat shrinkage, orange peel, and blister. The adhesive strength between the label and the hollow container was 334 g / 15 mm width. The hue measured from the label of the label-bonded yellow hollow container has an L value of 91.7, an a value of -8.1, and a b value of +4.
It was 7.4 and the opacity was 81.5%. Again 1
A yellow block copolymer hollow container having no label attached to 25 of the 10,000 hollow containers was found.

(Comparative Example 1) A thermosensitive adhesive "Adcoat 1790" was applied to the back surface of a polypropylene biaxially stretched film having a thickness of 95 µm and dried at 80 ° C to give a thickness of 99 µm.
Thus, a laminated film having a two-layer structure with m and an opacity of 3% was obtained. This was embossed in the same manner as in Example 1, and then the surface side of the biaxially stretched film was subjected to red gravure printing. Then, punching and blow molding were performed. Hollow containers having no label attached to 784 of 1,000 molded hollow containers were found.

(Example 5) B / A / C / obtained in Example 1
On the B side of the transparent laminated film of D, the manufacturer, the design and the trade name were gravure printed in black. The heat-sensitive adhesive layer D of this printed laminated film was subjected to embossing (linear) with 16 lines and a valley depth of 4 μm, and then punched to form a fan-shaped bottom plate having a diameter of 53 mm and a peripheral wall height of 28 cm. A blank for the differential pressure molding cup was obtained.

This blank was fixed in the cavity of the lower female mold of the compressed air vacuum mold so that the printing side was in contact with the cavity surface of the mold, and then polypropylene and polyethylene containing 1.5% by weight of red pigment were laminated. 5 cm of the lower female mold of the melted sheet (about 200 ° C.) was placed on the lower female mold using a pressure air vacuum forming machine made by Unic so that the polyethylene was on the outside of the container.
Guide it upwards, reduce the pressure through the pressure reducing hole at the bottom of the lower female mold, and let the blank adhere to the inner surface of the mold, and 4 kg / cm.
² G of compressed air is supplied from the air supply port side of the upper mold, the polypropylene sheet is pressure bonded to the inner surface of the mold, and Bragg assist molding is performed for 10 seconds, and trimming is performed to obtain an average wall thickness of 550 to 6
A red container mainly made of cup-shaped polypropylene decorated with a blank of 00 μm was molded.

In the label-attached red container thus manufactured, the blank was not discolored by printing, and the blank was not deformed. Further, the adhesive strength between the cup-shaped container body and the blank was as strong as 283 g / 15 mm width, and the blank could not be peeled off by hand.

[0046]

EFFECTS OF THE INVENTION A transparent or semi-transparent label for in-mold molding which enables multi-color printing by offset printing or screen printing and facilitates automatic insertion of a label into a mold by a label inserter. Is.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an in-mold molding label.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G09F 3/00-3/10 B32B 27/00

Claims (2)

(57) [Claims] 1. A biaxially stretched film of a thermoplastic resin having a melting point of 140 ° C. or higher is used as a base material layer (A), a primer layer (B) is provided on the front surface side, and a back surface side of the base material layer is provided. Is provided with a primer layer (C), the surface of the primer layer (C) is further provided with a thermosensitive resin adhesive layer (D), and the surface of the thermosensitive resin adhesive layer (D) is embossed, and The primer layer (1) of the primer layer (B) or the primer layer (C), or the laminated layer having an opacity of 20% or less in which an anti-blocking agent is blended in an amount of 0.1 to 3% by weight in both layers ( The label for in-mold molding which is printed on B). 2. The label for in-mold molding according to claim 1, wherein the biaxially stretched film (A) is a polypropylene biaxially stretched film.