JP2001129878A - Label-pasted hollow container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an in-mold label-pasted hollow container, no impact strength of which is impaired. SOLUTION: In a multilayered or a single-layered label-pasted hollow container, in which the pasting of a label is executed simultaneously with a molding, and its layer constitution, at least a surface layer, onto which the label is pasted, is made of a polyolefin composition including 10 to 100 wt.% of an ethylene-α-olefin copolymer, which is manufactured by employing a metallocene-based catalyst, has a melt flow rate of 1.0 to 200 g/10 min, and a density of 0.850 to 0.915 g/cm3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow container obtained by a so-called in-mold label sticking method, in which a label is stuck to a container at the same time as a hollow molding, and more particularly to a method of reducing a drop strength caused by sticking a label. The present invention relates to an improved label-attached hollow container.

[0002]

2. Description of the Related Art Conventionally, a hollow molding method is one of the main molding methods of polyolefin, and a hollow molded body obtained by the molding method is used in a large amount in containers such as various bottles in the fields of food, cosmetics, and medicine. However, various printed labels are attached at the same time as molding for the purpose of increasing the commercial value at the stage of commercialization or for the purpose of displaying the contents and the like.
The pasting of these labels has been conventionally performed continuously by an automatic labeler machine or the like after the molding of the container, but in recent years, these steps have been omitted, and the label is directly adhered at the time of molding the container. The in-mold label sticking method is performed. Such an in-mold label sticking method is particularly suitable for containers such as softened containers such as mayonnaise and ketchup, so-called squeeze (squeezed) containers, which are difficult to maintain the shape of the containers themselves during labeling, as well as houses, kitchens and automobiles. It is a suitable method for attaching containers for cleaning agents for clothing, detergents for clothing, bleaching agents and the like.

[0003]

However, even in such an in-mold label sticking method which is a preferable sticking method, wrinkles, blisters and dents around the label which occur during labeling in a mold from a practical point of view. However, there are minor problems such as the label being easily peeled off at the time of use.However, for these, reports on the label operation method in the mold and the improvement from the label material itself have been reported, and gradually These improvements are being made.

[0004] On the other hand, besides the above-mentioned minor problems, the label is temporarily fixed in a mold at the time of in-mold molding, but since the label itself has a thickness, the label-attached portion and the label-attached portion are not attached. A slight dent is formed at the boundary with the unattached part, stress is concentrated in this dent when an impact is applied to the container, and destruction occurs at the boundary where the stress is concentrated, cracks occur, and label There is a big problem that the impact strength at the time of dropping the attached hollow container is greatly reduced. When the container is actually dropped, especially when the container is filled with contents, stress concentrates on the boundary between the part where the label is attached and the part where the label is not attached, and a large force is applied. Is added, cracks are generated from this boundary portion, and they are broken, causing serious problems such as scattering of contents. In addition, the weight and thickness of the container itself are being reduced at the same time due to the recent increase in environmental friendliness, and the problem of reduction in impact strength due to sticking of a label is a more important improvement task.

As a solution to such a problem, it is conceivable to make the label into a thin film or to eliminate the corners of the label or the sharp corners of the cutting section. This problem has not yet been fully resolved, as it is cost-constrained and not an essential solution.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above problems, and as a result, have found that by using an in-mold bonding method, a hollow container with a label that does not impair the impact strength of the container can be obtained. To solve these problems, a polyolefin composition layer containing a specific amount of a specific ethylene-α-olefin copolymer by a metallocene catalyst is formed at least in a portion of the container where a label is to be attached. It has been found that the present invention can be performed, and the present invention has been completed. That is, the present invention relates to a container to which a label is attached at the same time as molding, and in a layer structure of the container, at least a surface layer to which a label is attached is manufactured using a metallocene-based catalyst. 0.0-200 g / 10 min, density 0.850-0.9
A multi-layer or single-layer label-adhered hollow container formed from a polyolefin composition containing 10 to 100% by weight of an ethylene-α-olefin copolymer of 15 g / cm ³ .

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the label-attached hollow container of the present invention, a specific ethylene-α-olefin copolymer produced by a metallocene-based catalyst used at least for a surface layer to which a label is attached is 190 ° C .; The melt flow rate under a load of 16 kg is 1.0 to 200 g / 10 min, preferably 2.0 to 100 g / 10 min. If the melt flow rate is less than 1.0 g / 10 min, the surface of the container tends to be roughened, and if it exceeds 200 g / 10 min, the effect of improving the strength is poor. The density is 0.850-0.915g /
cm ³ , preferably 0.85 to 0.90 g / cm ³ . If the density is less than 0.850 g / cm ³ , no further improvement effect is expected in the strength improvement, and it becomes difficult to manufacture with known manufacturing techniques, which is not economically preferable.
If it exceeds 0.915 g / cm ³ , the effect of improving strength will be poor.

The ethylene-α-catalyzed by metallocene catalyst
The olefin copolymer is a so-called metallocene catalyst comprising a metallocene-alumoxane catalyst or a compound which reacts with a metallocene compound and a metallocene compound to form a stable anion as disclosed in, for example, WO 92/01723. Using a gas phase method, a slurry method, a solution method, or JP-A-56-18607,
No. 58-225106, the pressure is 100 kg / cm ² or more, preferably 200 to ² ,
000 kg / cm ² , a temperature of 125 ° C. or more, preferably 130 to 250 ° C., particularly 150 to 200 ° C., by a high-pressure ionic polymerization method carried out under reaction conditions, ethylene and an α-olefin having 3 to 10 carbon atoms, specifically Typically propylene,
It is obtained by copolymerization with butene-1, pentene-1, hexene-1, 4-methylpentene-1, octene-1 and the like.

In the label-attached hollow container of the present invention, the polyolefin component used for at least the surface layer to which the label is attached, excluding the above-mentioned ethylene-α-olefin copolymer by a metallocene catalyst, is a polyolefin component which is conventionally used. A known polyolefin material used for a hollow container may be used. Specific examples include polypropylene, propylene-ethylene copolymer, high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, branched low-density polyethylene, polyolefin-based resins such as ethylene-vinyl acetate copolymer, A plurality may be simultaneously mixed. Particularly, a material having a large swelling behavior at the time of melting within a range that does not hinder the outer appearance of the container is more preferable because the boundary between the sticking label and the container does not easily become a shape where stress is easily concentrated.

[0010] Polypropylene, propylene-ethylene copolymer, high-density polyethylene, medium-density polyethylene, and linear low-density polyethylene are known as coordination compound catalysts such as Ziegler-Natta catalysts or known reduction type or supported type catalysts. It is obtained by polymerization using an active catalyst by a gas phase method, a slurry method, a solution method, or the high-pressure ion polymerization method described above. Further, the branched low-density polyethylene, ethylene-vinyl acetate copolymer, preferably using a tank reactor or a tubular reactor, in the presence of a radical polymerization initiator, a polymerization pressure of 1,
400-3,500 kg / cm ² , polymerization temperature 150-3
It is obtained by polymerizing ethylene at 50 ° C. or by adding a vinyl acetate monomer to the ethylene to copolymerize ethylene and vinyl acetate.

The composition ratio of the ethylene-α-olefin copolymer based on the metallocene catalyst in the polyolefin composition used in at least the surface layer to which the label is attached is 10 to 100% by weight, preferably 20 to 1% by weight.
It must be 00% by weight. If the composition ratio is less than 10% by weight, the effect of improving the drop strength of the container becomes poor, which is not preferable. When the label sticking hollow container has a multilayer structure, the composition ratio of the ethylene-α-olefin copolymer in the polyolefin composition forming the surface layer is 50 to 100% by weight. Is preferred.

The polyolefin composition may be mixed and kneaded with a generally used single-screw extruder or twin-screw extruder after mixing the components to form pellets, or may be directly used after mixing. However, at this time, depending on the purpose and application, various additives conventionally used in this field, such as antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, neutralizing agents, antistatics Agent, flow improver, nucleating agent,
Alternatively, it is possible to add a coloring agent such as an organic pigment or an inorganic pigment.

Next, in the label hollow container of the present invention,
It is essential that the polyolefin composition is used in the surface layer portion of the container to form a surface layer, but it is essential to form a single layer using only the polyolefin composition, or a multilayer structure with other materials. Alternatively, various selections can be made according to the intended use. In the case of a multilayer structure, the polyolefin component of the polyolefin composition used for the surface layer portion excluding the ethylene-α-olefin copolymer by the metallocene catalyst and the resin material constituting the inner layer are the same or the same. It is more preferable to use different kinds of polyolefin materials because the adhesion between the layers is improved and there is no need to provide a new adhesive layer. The inner layer side may include a reclaimed material layer of the inner and outer layers, a barrier resin layer such as EVOH, and an adhesive layer. In the case of a multilayer structure, the thickness of the surface layer portion of the container is 10 to 500 m
μ, preferably 20 to 300 mμ, 30
% Or less, preferably 20% or less is economically desirable.

The label-attached hollow container of the present invention has a density of 0.850 to 0.915 g / cm ³ of ethylene-α- produced by using a metallocene-based catalyst in the surface layer of the container. The olefin copolymer has the original purpose of suppressing the occurrence of destruction at the boundary between the container and the label, and at the same time has the effect of being a modifier that has excellent compatibility with existing polyolefin materials and improves impact strength. In particular, in the case of a single-layer structure, the strength of the base material of the container itself is also improved. As a result, besides the boundary between the container and the label sticking area, the impact strength is improved even at the pinch-off portion and the notch-like portion where the stress is easily concentrated in shape, and the lighter and thinner thickness of the container according to the increase in environmental compatibility. It can be said that it is also suitable for the demand for the production.

The label to be attached to the label-attached hollow container of the present invention is generally a substrate resin layer, a printed layer and an overcoat layer on the surface side, and a contact surface with the container on the back side. A laminated type label having a multilayer structure of three or more layers, on which a hot melt adhesive layer is formed, is used.
As the material of the laminated base resin, a synthetic paper type or a type formed of a stretched film made of a thermoplastic resin such as crystalline polypropylene is generally used, and specifically, polypropylene, propylene-ethylene copolymer , High-density polyethylene, polyolefin resin such as medium-density polyethylene, polyethylene terephthalate resin,
Polyvinyl chloride resin, nylon-6, nylon-6,6
Examples thereof include films of polyamide resin such as polyamide resin, ABS resin, and ionomer resin. Preferably, polypropylene, high-density polyethylene, and polyethylene terephthalate resin have a melting point of 130 to 280 ° C. May be used as a mixture of two or more. Among these resins, a polypropylene-based resin is preferable in terms of chemical resistance, cost, and the like.

Alternatively, a film in which an inorganic or organic fine powder is blended in the resin in an amount of 8 to 80% by weight, a film stretched in one direction or two directions by a known method, or a latex containing an inorganic filler on the surface is coated. Engineered films, films on which aluminum is deposited or bonded, and the like can also be suitably used.

The hot-melt adhesive in the hot-melt adhesive layer has an ethylene / vinyl acetate copolymer or ethyl acrylate content having a vinyl acetate content of 5 to 40% by weight, preferably 10 to 40% by weight. 5-40% by weight,
Preferable examples include 10 to 40% by weight of an ethylene-based resin such as an ethylene-ethyl acrylate copolymer, and a resin obtained by blending a tackifier such as a petroleum resin with these resin components.

The hot-melt adhesive is generally applied to the above-mentioned base resin at a thickness of 3 to 40 μm, preferably 3 to 15 μm. The printing layer and the overcoat layer are formed to have a normal printing thickness or the thickness of the overcoat layer. The thickness of these labels is usually in the thickness range of 40 to 250 μm, preferably 50 to 20 μm.
The thickness range is 0 μm. If the thickness is less than 40 μm, in the in-mold labeling method, it is difficult to separate the stacked labels one by one in the sticking process, and the insertion of the label into the mold by the label inserter is not fixed at a proper position. Problems are easy to occur. Conversely, 250 μm
It is not preferable that the viscosity exceeds the range, since the strength of the boundary portion between the container and the label is reduced even when the composition of the present invention is used. From the viewpoint of adhesive strength, it is preferable that the resin is integrated by in-mold molding. In particular, a heat-sealing resin having a melting point lower than the melting point of the material resin of the film on the back surface of the inorganic fine powder-containing thermoplastic resin film is preferable. A layer formed of a multilayer structure film, and a synthetic paper label obtained by stretching the multilayer structure film at a temperature equal to or higher than the melting point of the heat sealing resin and lower than the melting point of the inorganic fine powder-containing thermoplastic resin is preferable. . It is preferable to apply embossing to the heat-sealing resin layer of these labels for the purpose of preventing the occurrence of blisters during in-mold molding.

The molding of the label sticking container of the present invention can be performed by a known blow molding method or apparatus as long as the cross-sectional configuration schematically shown in FIG. 1 can be obtained in addition to the in-mold equipment. In the blow molding, generally, a material resin constituting a container is heated and melted by an extruder type hollow molding machine,
The softened parison is continuously or intermittently extruded from the die, then one end of the parison is closed with a mold and closed, and the parison is blown from the other end into one of the closed parisons. Inflating itself, pressing the outer part of the parison against the inner wall of the mold with the pressure inside the parison, forming it along the shape of the inner wall of the mold, and cooling and hardening it to form a blow-molded container Can be.

Various methods are known at present for attaching an in-mold label, but it is preferable to use a form printing method, an automatic inserter method, and the like described below. For example, a pre-printed continuous label material is die-cut in a molding apparatus, and the cut individual label is pushed through a mold with a ram and guided into a blow mold. A label is inserted into a mold by a form print method of labeling a container by blow molding a parison by the above blow molding method or by inserting the label into a mold by a blower using the blow molding method. There is an automatic inserter method in which a container is labeled by blow molding, and the label is suction-held through a vacuum hole in the inner wall surface of the mold until the parison is blow molded.

According to the present invention, when a hollow container to which a label is attached is obtained by the in-mold label method, at least the surface layer of the container to which the label is attached is coated with a specific ethylene-α-olefin by a metallocene catalyst. By forming the polyolefin composition layer containing the polymer, it is possible to prevent the impact strength from being lowered when the container is dropped.

[0022]

EXAMPLES Hereinafter, the label sticking container of the present invention will be described in more detail with reference to Examples in order to describe it in more detail. The methods for measuring and evaluating physical properties and the materials with the respective titles used in Examples and Comparative Examples are as follows. 1. Methods for measuring and evaluating physical properties (1) MFR: polyethylene is JIS-K-6760
And polypropylene was measured according to JIS-K6758. (2) Density: Measured according to JIS-K-7112. (3) Drop strength: In the drop test, the obtained container was hermetically filled with water at room temperature and kept in an atmosphere of 5 ° C. for 24 hours, and then each of the three containers was bottled on a concrete floor surface for each test condition. The sample was dropped vertically from the bottom surface, and the presence or absence of cracks from the dent of the label boundary was measured according to the following criteria while changing the height every 50 cm. ：: None. ×: Cracks or breakage occurred at the label boundary.

2. Materials (1) MPE-1: Ethylene-hexene-1 copolymer produced by metallocene catalyst (Nippon Polychem Co., Ltd.)
(2) MPE-2: an ethylene-hexene-1 copolymer produced by a metallocene catalyst (Nippon Polychem Co., Ltd.)
(3) HD-1: high-density polyethylene manufactured using a titanium-based catalyst (4) HD-2: high-density polyethylene manufactured using a chromium-based catalyst (5) PP-1: Propylene-ethylene random copolymer produced using a titanium-based catalyst (6) PP-2: Propylene-ethylene random copolymer produced using a titanium-based catalyst

Examples 1 to 3 and Comparative Examples 1 and 2 A small direct blow molding machine TL manufactured by Tahara Co., Ltd. was used at a predetermined mixing ratio using the respective materials shown in Table 1.
5543L (extruder 55 mmφ, single-layer die) at a molding temperature of 200 ° C., a round bottle shape as a mold (body diameter: 80 mm)
32g single layer bottle with φ, inner volume: 500cc)
(Thickness of the torso at the part where the in-mold label is attached: 0.9 to
1.0 mm). In Examples 2 and 3, ethylene-α by a metallocene catalyst was used.
-The olefin copolymer component and the other components were uniformly mixed at a predetermined weight ratio, melt-kneaded by a single screw extruder, extruded, and pelletized before use. At the time of each molding, an in-mold label (synthetic paper “Yupo ITE105” manufactured by Oji Yuka Synthetic Paper Co., Ltd., horizontal 70 mm ×
(Vertical 100 mm × 100 μm thickness) was inserted by an automatic inserter, and the label was fixed to the inner surface of the mold by a suction hole. Then, the mold was closed and hollow molding was performed to obtain an in-mold label sticking bottle. The drop strength of the obtained resin bottle was evaluated, and the results are shown in Table 1.

Examples 4 to 7 and Comparative Examples 3 and 4 Using the respective materials shown in Table 1, a small direct multilayer blow molding machine manufactured by Vecum (main extruder 50 mmφ, auxiliary Extruder each 40mmφ, multilayer die)
The molding temperature is 180 ° C on the surface side and 200 ° C on the main layer side.
A two-layer, two-layer bottle having a flat shape (internal volume: 650 cc) was formed as a mold so as to have a basis weight of 41 g (body thickness of the in-mold label attachment site: 0.8 to 0.9 mm). In Examples 5 and 7, the ethylene-α-olefin copolymer component and the other components were uniformly mixed at a predetermined weight ratio by a metallocene catalyst, melt-kneaded by a single screw extruder, and extruded beforehand. It was used after pelletizing. At the time of each molding, an in-mold label (a synthetic paper "Yupo ITE1" manufactured by Oji Yuka Synthetic Paper Co., Ltd.)
05 ", horizontal 70mm x vertical 100mm x 100μm
Thickness) was inserted, and the label was fixed to the inner surface of the mold by a suction hole. Then, the mold was closed and hollow molding was performed to obtain an in-mold label sticking bottle. The drop strength of the obtained resin bottle was evaluated, and the results are shown in Table 1.

[0026]

[Table 1]

[0027]

According to the label-attached hollow container of the present invention obtained by in-mold label molding, a specific ethylene-α-olefin copolymer with a metallocene catalyst is specified in at least a portion of the container where a label is to be attached. By forming a polyolefin composition layer that has been blended in an amount, even when a high impact such as at the time of a drop is applied, a boundary portion between a portion where the label is stuck and a portion where the label is not stuck where the stress is easily concentrated. Thus, a container having excellent impact strength can be obtained without cracking or breaking.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a label-attached portion in each of a single layer (a) and a multilayer (b) of a label-attached hollow container of the present invention.

[Explanation of symbols]

 1 In-mold label 2 Surface layer 3 Inner layer

Continuing from the front page (72) Inventor Shuichi Furushio 310 Minordai, Matsudo-shi, Chiba Pref. Yoshino Industrial Research Laboratory Co., Ltd. Inside the Materials Development Center (72) Inventor Shigeto Kimura 3-1 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Japan F-term in the Materials Development Center, Polychem Corporation (Reference) 3E095 AA20 BA10 FA30 4F208 AA03 AA04E AA05 AA11 AD05 AD09 AG07 AH55 AR15 AR17 AR18 LB01 LB19 LB22 LG01 LG06 LG14

Claims (4)

[Claims] 1. A container to which a label is attached at the same time as molding, and in a layer structure of the container, at least a surface layer to which the label is attached is manufactured using a metallocene catalyst. 0 to 200 g / 10 minutes,
A multilayer or single-layer label-attached hollow container formed from a polyolefin composition containing 10 to 100% by weight of an ethylene-α-olefin copolymer having a density of 0.850 to 0.915 g / cm ^3. . 2. The polyolefin composition forming the surface layer contains the ethylene-α-olefin copolymer in an amount of 50 to 1%.
The multi-layer label-attached hollow container according to claim 1, which contains 00% by weight. 3. The polyolefin composition forming the surface layer contains the ethylene-α-olefin copolymer in an amount of 10 to 1%.
The multi-layer or single-layer label-attached hollow container according to claim 1, wherein the container is composed of 00% by weight and 0 to 90% by weight of high-density polyethylene. 4. The polyolefin composition forming the surface layer contains the ethylene-α-olefin copolymer in an amount of 10 to 1%.
The multi-layer or single-layer label-attached hollow container according to claim 1, comprising 00% by weight and 0 to 90% by weight of polypropylene.