JPH0585414B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to labeled containers by attaching labels in molds, and more specifically, the present invention relates to containers with labels attached in molds, and more specifically, labels are attached in molds to polyolefin containers, which have excellent heat resistance and chemical resistance. The present invention relates to a container with a label. (Prior art) Attaching a label that indicates the contents to a hollow container has an important meaning in terms of packaging technology because it increases the commercial value of the packaged product and stimulates consumers' desire to purchase it. . It has been known for a long time to apply labels to hollow containers by in-mold labeling, in which the label to be affixed to the inner surface of the cavity of a molding die is held by means such as vacuum suction, and the plastic is then affixed within the mold. A method of blow-molding the parison is generally employed (for example, Japanese Patent Application Laid-Open No. 61-202818). It is also already known to use a laminate of a solid polymer layer, a foam layer, and a polymer solution layer as a plastic label (Japanese Patent Application Laid-Open No. 1983-1989-1).
123333, 60-183343 and 60-242490). (Problems to be solved by the invention) As labels for in-mold label operations, labels based on plastic film have advantages such as being able to print on the back side, providing clear images, and having excellent stain resistance. The use of heat-sensitive adhesives, particularly hot-melt adhesives, is advantageous in that the heat of the plastic container wall being formed is used to effect the bonding. Conventionally, such hot-melt adhesives for labels have been used which mainly consist of an ethylene-vinyl acetate copolymer, with a tackifier added thereto if necessary. However, known hot melt adhesives have not yet been fully satisfactory in terms of heat resistance and chemical resistance. For example, when hot filling is performed for the purpose of improving the shelf life (sterilization) of the contents, labels tend to shift and adhesive strength decreases during transportation. Furthermore, in the case of containers for cosmetics, toiletries, medicines, etc., the label may peel off or the adhesive strength may decrease due to the effects of the contents adhering to the outside of the container during filling. Therefore, it is an object of the present invention to attach a label to a polyolefin plastic container with excellent adhesive strength through an in-mold label operation, and to have an adhesive part of the label that has excellent heat resistance and chemical resistance. Provide a labeled container with the following information: (Means for Solving the Problems) According to the present invention, the container comprises a blow-molded container made of polyolefin plastic and a label affixed to the outer surface of the container in a mold during molding, and the label is a label base material. and the chlorine content is 10 to 50% by weight, and the crystal melting peak temperature is 130 to 85°C and the heat of crystal fusion at the above peak is 0.5 to 10 cal. /g, and the label is bonded to the outer surface of the container via the adhesive layer by in-mold label attachment. A labeled container with excellent heat resistance and chemical resistance is provided. (Function) The present invention provides that when a specific chlorinated polypropylene is used as an adhesive for a label for attaching an in-mold label, it provides excellent adhesion to a polyolefin plastic container molded in a mold, and furthermore, This is based on the discovery that the adhesive part has sufficient heat resistance to withstand hot filling of contents, and also exhibits excellent chemical resistance when it comes in contact with cosmetics, toiletries, and various chemicals. be. When attaching labels by blow molding plastics, the small amount of heat in the plastic being molded must be used for adhesion, while the mold must be cooled for ease of molding. Therefore, there is a constraint that thermal bonding must be completed with a small amount of heat and within a short time. In this way, in-mold labeled containers have insufficient adhesion between the label and the container;
In containers such as shampoo, there is a strong adhesion deterioration effect due to the surfactant in the contents that drips from the container mouth, and in hot filling and retort sterilization, the more adhesion is possible at a relatively low temperature, the better. During sterilization and heating, the adhesive strength of the label decreases, resulting in peeling or misalignment. In the present invention, the chlorine content is 10 to 50% by weight, the crystal melting peak temperature is 130 to 85°C, and the heat of crystal fusion at the above peak is in the range of 0.5 to 10 cal/g as measured by a differential scanning calorimeter. By providing an adhesive layer mainly made of a certain chlorinated polypropylene on the label, as described in the example below, the label can be attached between the label containers by in-mold labeling.
While an adhesive force of 400 g/mm width or more can be obtained, even when this labeling container is heated at 85°C, an adhesive force of 200 g/15 mm width or more is maintained, and it also maintains an adhesive force of 200 g/15 mm width or more when immersed in shampoo liquid etc. Even in cases where the adhesive is removed, no peeling occurs and the adhesive strength is maintained. In the chlorinated polypropylene used in the present invention, the crystal melting temperature is set so that it has heat resistance that can withstand hot filling, etc., while the crystal melting heat amount is set so that sufficient adhesion is achieved when attaching the label inside the mold. has been done. These crystalline melting properties (related to crystallinity) are also related to chemical resistance. If the chlorine content is less than the above range, the solubility will decrease, making the film forming operation difficult, and the heat of crystal fusion will be greater than the above range, which will tend to reduce the adhesive strength when attaching the label in the mold. Garu. On the other hand, if the chlorine content is higher than the above range, the polarity of the adhesive will be too strong, resulting in poor adhesion to polyolefin plastics. Furthermore, if the peak temperature T is higher than the above range, the adhesion to polyolefin plastics (during in-mold label operation) will decrease, and if it is lower than the above range, the heat resistance will decrease. If the amount of heat C is larger than the above range, the heat adhesion during in-mold label operation will be unsatisfactory, and if it is smaller than the above range, the heat resistance will likely be unsatisfactory. (Preferred Embodiment of the Invention) Label Structure The label of the present invention comprises a label base material and an adhesive layer of chlorinated polypropylene applied to one surface thereof. Label substrates generally consist of plastic film or a composite of a plastic film layer and a metal layer. Naturally, a printing ink layer is provided on either side of the label base material. In FIG. 1 showing an example of the label of the present invention,
This label 1 includes a plastic film base material 2,
It consists of a printing ink layer 3 applied to the back side and a chlorinated polypropylene adhesive layer 4 applied to the surface of the printing ink layer. In FIG. 2 showing another example of the label of the present invention, this label 1a consists of a plastic film base material 2, a printing ink layer 3 applied to the back side of the plastic film base material 2, and a metal vapor deposition layer provided on the printing ink layer. It consists of a metal foil layer 5 and a chlorinated polypropylene adhesive layer 4 applied on top of the metal layer 5. If necessary, an adhesive primer is applied between the metal layer 5 and the chlorinated polypropylene adhesive layer 4. Further, the label of the present invention can also have a layered structure as shown in FIG. In FIG. 3, this label 1b is a laminate of a plastic film outer layer 2, a printing ink layer 3 applied on the back side, a plastic film intermediate layer 6 having a metal vapor deposited layer 5a on the surface, and a chlorinated polypropylene adhesive inner layer 4. It consists of This label 1b is made by pasting together a plastic film printed on and a plastic film coated with metal vapor deposition using an adhesive or an adhesive primer, with the printing ink layer and metal vapor deposition layer facing each other. It is formed by applying a chlorinated polypropylene adhesive to the side of the laminated metallized film. Furthermore, a layered structure as shown in FIG. 4 is also possible. In FIG. 4, this label 1c is a lamination of a plastic film outer layer 2, a printing ink layer 3 applied on the back side, a plastic film intermediate layer 6 having a metal vapor deposited layer 5a on the inner surface, a chlorinated polypropylene adhesive, and an inner layer 4. It consists of the body. This label 1c is made by laminating a plastic film printed on and a plastic film coated with metal vapor deposition with an adhesive so that the printing ink layer and the plastic film surface face each other with an adhesive. Apply adhesive primer to the surface,
It is formed by applying a chlorinated polypropylene adhesive thereon. The plastic film substrate 2 is generally uniaxially or biaxially stretched and transparent so that the printed layer 3 is visible through the film layer. The printing layer 3 is so-called back-printed with printing ink, and may be a multiple printing layer such as an image area and a background, and the background may be made of a metal layer in the form of vapor deposition or foil. Good too. Each material The chlorinated polypropylene used in the present invention preferably has a chlorine content in the range of 10 to 50% by weight, particularly 20 to 40% by weight.
The crystal melting peak temperature T ₁ is between 130 and 85
℃, especially 115 to 85℃, the heat of crystal fusion C at the above peak is 0.5 to 10 cal/g, especially 1 to 5 cal/g.
It is better to be in the g range. If the chlorine content is less than the above range, the solubility will decrease, making the film forming operation difficult, and the heat of crystal fusion will be larger than the above range, which will tend to reduce the adhesive strength when attaching the label in the mold. There is. On the other hand, if the chlorine content is higher than the above range, the polarity of the adhesive will be too strong and its adhesion to polyolefin plastics will be reduced. Furthermore, if the peak temperature T is higher than the above range, the adhesion to polyolefin plastics (during in-mold label operation) will decrease, and if it is lower than the above range, the heat resistance will decrease. If the amount of heat C is larger than the above range, the heat adhesion during in-mold label operation will be unsatisfactory, and if it is smaller than the above range, the heat resistance will likely be unsatisfactory. FIG. 5 shows a DSC curve of chlorinated polypropylene used in the present invention. The chlorinated polypropylene of the present invention includes aromatic hydrogens such as toluene, ethylbenzene, xylene; halogenated hydrocarbons such as trichlorethylene, tetrachloroethylene, methylchloroform; alicyclic hydrocarbons such as cyclohexane, methylcyclohexane, It is soluble in ethylcyclohexane, etc., and is applied in the form of a solution and dried to form a film on the adhesive layer. Chlorinated polypropylene at a concentration of 15g/100ml in toluene
Measured at a temperature of 25°C, 0.1 to 200 poise, especially
Preferably, it has a viscosity of 0.1 to 50 poise.
In addition, the thickness of the adhesive layer is 0.1 to 50 μm, especially 1 μm.
It is preferably in the range of 10 μm to 10 μm. The adhesive layer used in the present invention contains various compounding agents,
For example, tackifiers, heat stabilizers, lubricants, plasticizers, fillers, etc. can be added. As the tackifier, rosin resin, terpene resin, petroleum resin, styrene resin, chroman-indene resin, etc. can be used.
As the heat stabilizer, a metal soap stabilizer or an organic tin stabilizer is used. Epoxy-based lubricants, wax-based lubricants, etc. are used as the lubricant, dioctyl phthalate, fatty acid mono- or diglyceride, etc. are used as the plasticizer, and inorganic or polymeric microbeads are used as the filler. In the present invention, the plastics constituting the base film of the label include, for example, crystalline polypropylene, crystalline propylene-ethylene copolymer, crystalline polybutene-1, crystalline poly4-methylpentene-1, low-, medium- Or polyolefins such as high-density polyethylene; aromatic vinyl polymers such as polystyrene and styrene-butane diene copolymer; halogenated vinyl polymers such as polyvinyl chloride and vinylidene chloride resin; acrylonitrile-
Nitrile polymers such as styrene copolymers, acrylonitrile-styrene-butadiene copolymers; polyamides such as nylon 6, nylon 6,6, para- or metaxylylene adipamide; polyethylene tetophthalate, polytetramethylene terephthalate, etc. Examples include polyesters; various polycarbonates; and thermoplastic resins such as polyacetals such as polyoxymethylene. This stretched film generally has a thickness of 20 to 300 μm, particularly preferably 50 to 150 μm. As the metal layer, a foil or vapor deposited layer of a metal with metallic luster, such as aluminum, tin, or copper, is used. The foil generally used has a thickness of 1 to 15 μm, particularly 5 to 9 μm, while in the case of a vapor-deposited layer, a thickness less than the above-mentioned foil thickness is used. For laminating printed stretched film substrates and metal foils, or laminated printed stretched film substrates and metallized films, urethane adhesives, epoxy adhesives, or acid-modified olefin resin adhesives may be used depending on the film substrate. This can be done using an agent. In the present invention, the plastic film base material is not necessarily limited to a transparent material; for example, a foamed stretched plastic film can also be used. In this case, a printing ink layer is provided on one surface (front side) of the foamed film, and an adhesive is provided on the other surface (back side). When a chlorinated polypropylene adhesive layer is provided on the printing ink layer, it is preferable to use a printing ink containing chlorinated polypropylene or polyester urethane resin as a binder, so that there is a good bond between the two layers. A good adhesion can be obtained. In-mold label operation In FIG. 6 for explaining the in-mold label operation, in step A, prior to blow molding the plastic parison, the blow molds 7a and 7b are in an open state, and the cavity of at least one of them is The label 1 is previously applied to the surface 8. That is, the cavity surface 8 has a portion that supports the label 1, a vacuum suction mechanism 9 is provided in this portion, and the label 1 is held on the cavity surface 8 by a suction. In this case, the label is positioned such that the plastic film base 2 is on the outside and the hot melt adhesive resin layer 5 is on the inside. The application and fixing of the label 1 to the cavity surface 8 is not limited to suction, but can also be carried out, for example, by electrostatic electricity. Next, in step B, the molten plastic parison 11 is extruded from the die 10, the blow molds 7a and 7b are closed, and pressurized gas is blown into the closed parison 11. In step C, the parison expanding in the mold is held on the mold surface and pressed against the label 1 to bring them into close contact, and the expanded parison comes into contact with the mold surface and is cooled to form the labeled container 12. becomes. Blow molding includes direct blow molding using horizontal rotary blow molding machines, vertical rotary blow molding machines, etc., as well as any blow molding methods such as injection blow molding, two-stage blow molding, sheet forming, and stretch blow molding. It can be done by method. As polyolefin plastics constituting the container, those exemplified for films are widely used. This container can have a single layer or multilayer structure, for example, a container made of a single layer of polyolefin, or a multilayer container made of polyolefin as an inner and outer layer and a gas barrier thermoplastic resin as an intermediate layer between them. Examples include containers. Gas barrier resins include ethylene-vinyl alcohol copolymers with an ethylene content of 50 to 20 mol%; polyamides containing xylylene groups; gas barrier polyesters; polymers containing high nitrile groups; vinylidene chloride resins, etc. Gas barrier resins known per se can be used. When there is no adhesiveness between the inner and outer layers and the intermediate layer, adhesive resins such as acid-modified olefin resins, various copolyamides, and various copolyesters may be contained between them. (Effects of the Invention) According to the present invention, by using chlorinated polypropylene as an adhesive for a label for attaching an in-mold label, excellent adhesion is achieved to a polyolefin plastic container molded in a mold, Moreover, the formed adhesive has the advantage of being heat resistant enough to withstand hot filling with contents, and also exhibiting excellent chemical resistance when it comes into contact with cosmetics, toiletries, and various chemicals. It was done. (Example) The present invention will be explained with the following example. Example 1 One side of a stretched polypropylene film with a thickness of 100 μm was printed with ink using polyester urethane as a binder, and the chlorine content was 26% by weight and the crystal melting peak temperature was 90%.
Chlorinated polypropylene having a heat of crystal fusion of 2.2 cal/g and a viscosity of 4 poise (25°C) in a 15 g/100 ml toluene solution was applied to a film thickness of 5 μm to form an adhesive layer. Next, a square label measuring 90 mm in length and 60 mm in width was punched out from the obtained label base material, and was attached to the surface of a bolt made of ethylene-propylene copolymer with a melting point of 157°C by the process shown in Figure 6. . In this case, the molten resin temperature of the ethylene-propylene copolymer parison was 210°C, and the blow mold temperature was 8°C. The appearance of the in-mold label bottle thus obtained was very good. In addition, when the adhesive strength between the label and the bottle was measured, it was 400g/15mm width when sampled in the bottle height direction (HD) and 600g/15mm width when sampled in the bottle width direction (WD). (A 90° peel test was performed at a peeling speed of 300 mm/min.) In addition, considering the adhesion of the label during hot filling, we measured the adhesive strength of the label at 85°C, and found that HD: 270 g / 15 mm width, WD ‥400g/15mm
It was wide and warm. Next, to test the adhesion of the label due to adhesion of the contents, the in-mold label bottle was immersed in rinse, hair tonic, and shampoo at 40°C for 24 hours. As a result, there was no abnormality in appearance of the labels for any of the contents. Adhesive strength: Rinse HD...450g/15mm width, Shampoo HD
‥510g/15mm width, Hair Tonik HD‥380g/
At 15mm width, there was almost no decrease. Example 2, Comparative Examples 1 and 2 Using various chlorinated polypropylenes with different chlorine contents, labels were made in the same manner as shown in Example 1 to form in-mold label bottles,
The adhesive strength between the label and the bottle was measured. Table 1 shows the results. Examples 3 and 4, Comparative Examples 3 and 4 In-mold label bottles were molded in the same manner as in Example 1 using various inks, adhesives, and bottle materials shown in Table 2. Then, the adhesive strength between the label and the bottle was measured at room temperature, 85°C. Also, during hair toning, conditioner, shampoo,
After the in-mold label bottle was immersed at 40°C for 24 hours, the appearance of the label portion and the adhesive strength between the label and the bottle were measured. The results are shown in Table 2.

【table】

【table】

[Table] Example 5 One side of a stretched polypropylene film having a thickness of 100 μm was printed with an ink using polyester urethane as a binder. Next, a primer is applied on top, aluminum is evaporated to a thickness of 500 Å, and a vinyl acetate-acrylic acid ester adhesive primer is applied, with a chlorine content of 23% by weight.
Chlorinated polypropylene with a peak crystal melting temperature of 94℃, a heat of crystal fusion of 2.6cal/g, 15g/100ml, and a viscosity of 6 poise (25℃) in toluene solution is applied to a film thickness of 5μ. Then, an adhesive layer was formed. Next, a square label with a length of 90 mm and a width of 60 mm was punched out from the obtained label base material, and was attached to the surface of a bottle made of ethylene-propylene copolymer with a melting point of 157°C by the process shown in Figure 6. . In this case, the molten resin temperature of the ethylene-propylene copolymer parison was 210°C, and the blow mold temperature was 8°C. The in-mold label bottle thus obtained had a metallic luster and was very good in appearance. In addition, when the adhesive strength between label bottles was measured, it was 430 g/15 mm width when sampled in the bottle height direction (HD) and 550 g/15 mm width when sampled in the bottle width direction (WD). Example 6 One side of a stretched polypropylene film with a thickness of 80μ was printed with an ink using polyester urethane as a binder, and 25μ polypropylene on which aluminum had been vapor-deposited in advance was coated with urethane-based polypropylene so that the aluminum-deposited surface and the printed surface faced each other. Laminate with adhesive. Next, the polypropylene side of the vapor-deposited polypropylene film has a chlorine content of 26%.
% by weight, peak temperature of crystal melting is 90℃, heat of crystallization is 2.2cal/g, 15g/100ml, and viscosity of 4 poise (25℃) in toluene solution is made of chlorinated polypropylene with a film thickness of 6μ. An adhesive layer was formed. Next, a square label with a length of 90 mm and a width of 60 mm is punched out from the obtained label base material, and is pasted on the surface of a bottle made of ethylene-propylene copolymer with a melting point of 157°C by the process shown in Figure 6. Ta. In this case, the molten resin temperature of the ethylene-propylene copolymer parison was 210°C, and the blow mold temperature was 8°C. The in-mold thus obtained had a glossy and very good appearance. In addition, when we measured the adhesive strength between the label and the bottle, HD: 350g/15mm width, WD: 400g/15mm width.
It was mm wide.

[Brief explanation of the drawing]

Figures 1, 2, 3, and 4 are diagrams showing examples of the cross-sectional structure of the label of the present invention, Figure 5 is a DSC curve of chlorinated polypropylene, and Figure 6 is a diagram showing the in-mold label operation. FIG. Reference number 1 is the label, 2 is the plastic film, 3 is the printing ink layer, 4 is the chlorinated polypropylene adhesive layer, 5 is the metal layer, 5a is the metal vapor deposition layer, 6
1 is a plastic film, 7 is a blow mold, 8 is a cavity surface, 9 is a vacuum suction mechanism, 10 is a die, 11 is a parison, and 12 is a container with a label.

Claims (1)

[Claims] 1 Consists of a polyolefin plastic blow-molded container and a label affixed to the outer surface of the container in the mold during molding, the label being a label base material,
Provided on the surface, the chlorine content is 10 to 50% by weight, the crystal melting peak temperature is 130 to 85°C, and the heat of crystal fusion at the above peak is 0.5 to 10 cal/g as measured by a differential scanning calorimeter. an adhesive layer mainly composed of chlorinated polypropylene in the range of and labeled containers with excellent chemical resistance.