JP6912422B2 - Heat sealant, insert film, and in-mold molded product - Google Patents

Description

The present invention relates to a heat sealant for in-mold molding, an insert film for in-mold molding using the heat sealant, and an in-mold molded body.

Conventionally, cup-shaped containers obtained by injection molding or the like of molten resin have been widely used as containers for food containers and daily necessities around water. Further, an insert film such as an in-mold label is used to impart designability to these containers. For example, an in-mold in which a molten resin is introduced into a mold in which an in-mold label having a pattern layer (color ink layer) and a heat-seal layer having a desired design is inserted, and a container integrated with the label is molded. By the molding method, a container having excellent design can be manufactured. Unlike containers obtained by attaching a printed label, for example, a container manufactured by such an in-mold molding method is less likely to generate mold even when placed around water, and the label is produced by friction. There is an advantage that problems such as peeling are unlikely to occur.

Various proposals have been made so far for in-mold labels. For example, an in-mold label provided with a heat-sealing layer containing a urethane resin and titanium oxide has been proposed (Patent Document 1).

Japanese Unexamined Patent Publication No. 2008-0835113

Since the heat seal layer is a layer that also serves as a base layer for ensuring the design of the adjacent pattern layer (color ink layer), it is required to show good concealment. NS. However, if the heat seal layer contains titanium oxide at a high concentration in order to improve the concealing property, there is a problem that the adhesiveness between the heat seal layer and the color ink layer or the container body arranged adjacent to each other is lowered. Is likely to occur.

The present invention has been made in view of the problems of the prior art, and the subject thereof is that it is possible to form a heat seal layer having high heat seal strength and excellent hiding power. The purpose of the present invention is to provide a heat sealant for in-mold molding. Another object of the present invention is to provide an insert film for in-mold molding using this heat sealant and an in-mold molded body.

As a result of diligent studies to solve the above problems, the present inventors used a resin component containing a chlorinated polypropylene and a chlorinated ethylene-vinyl acetate copolymer in a specific ratio, and specified this resin component and titanium oxide. We have found that it is possible to solve the above problems by blending in a ratio, and have completed the present invention.

That is, according to the present invention, the following heat sealant is provided.
[1] A heat sealant for in-mold molding containing a resin component and titanium oxide, wherein the resin component contains a chlorinated polypropylene and a chlorinated ethylene-vinyl acetate copolymer, and the chlorine in the resin component. The mass ratio of the content of polypropylene (A) to the content (B) of the chlorinated ethylene-vinyl acetate copolymer is (A) :( B) = 30: 70 to 95: 5, and the above. The mass ratio of the resin component content ((A) + (B)) to the titanium oxide content (C) is ((A) + (B)) :( C) = 10: 90 to 70. : 30 der is, further containing a monoisocyanate compound, the content of the mono-isocyanate compound, based on the total of the components other than the mono-isocyanate compound, 0.01 to 3.0% by mass Ru heat seal Agent.
[2] The heat sealant according to the above [1], which is used as a two-component liquid composition in combination with a curing agent.
[3] The above-mentioned [1] used for forming a heat seal layer arranged adjacent to a color ink layer formed of a two-component urethane color ink which is a combination of a urethane-based color ink and a curing agent. ] The heat sealant described in.

Further, according to the present invention, the insert film shown below is provided.
[ 4 ] An insert film for in-mold molding that is arranged in a state of being adhered to the surface of the main body of the molded body, and is a base material layer, a color ink layer, and the heat sealant according to the above [1] or [2]. An insert film which is a laminated film in which heat seal layers containing are laminated in this order.
[5] The insert film according to the above [4], wherein the color ink layer is formed of a two-component urethane color ink which is a combination of a urethane-based color ink and a curing agent.

Further, according to the present invention, the in-mold molded product shown below is provided.
[ 6 ] A state in which the molded body and the insert film according to [4] or [5] arranged on the surface of the molded body are provided, and the heat seal layer is adhered to the surface of the molded body. An in-mold molded body on which the insert film is arranged.

According to the present invention, it is possible to provide a heat sealant for in-mold molding capable of forming a heat seal layer having high heat seal strength and excellent hiding power. Further, according to the present invention, it is possible to provide an insert film for in-mold molding using this heat sealant and an in-mold molded product.

It is a partial cross-sectional view schematically showing one Embodiment of the insert film of this invention. It is a partial cross-sectional view which shows typically one Embodiment of the in-mold molded article of this invention.

<Heat sealant>
The heat sealant of the present invention is a heat sealant for in-mold molding containing a resin component and titanium oxide. The resin component contains chlorinated polypropylene and chlorinated ethylene-vinyl acetate copolymer, and the content of chlorinated polypropylene (A) and the content of chlorinated ethylene-vinyl acetate copolymer (B) in the resin component The mass ratio is (A) :( B) = 30: 70 to 95: 5. The mass ratio of the resin component content ((A) + (B)) to the titanium oxide content (C) is ((A) + (B)) :( C) = 10: 90 to It is 70:30. Hereinafter, the details of the heat sealant of the present invention will be described.

(Resin component)
The heat sealant contains a resin component containing chlorinated polypropylene (hereinafter, also referred to as “chlorinated PP”) and a chlorinated ethylene-vinyl acetate copolymer (hereinafter, also referred to as “chlorinated EVA”). The mass ratio of the chlorinated PP content (A) and the chlorinated EVA content (B) in the resin component is (A) :( B) = 30: 70 to 95: 5. Preferably, (A) :( B) = 35: 65-90: 10. Usually, when a heat sealant containing a large amount of titanium oxide is used, the adhesiveness (adhesion) to the resin molded body body such as the container body tends to decrease, and the heat seal strength tends to be insufficient. On the other hand, in the present invention, chlorinated resins such as chlorinated PP and chlorinated EVA are used, and these chlorinated resins are blended so as to have the above mass ratio. As a result, even when a relatively large amount of titanium oxide is contained, the adhesiveness to the molded product body can be sufficiently improved and excellent heat seal strength can be ensured.

The heat seal strength can be increased by using chlorinated PP and chlorinated EVA in combination instead of chlorinated PP alone or chlorinated EVA alone. If the proportion of chlorinated PP in the resin component is too small, the heat seal strength will be insufficient. On the other hand, if the proportion of chlorinated EVA in the resin component is too small, it becomes difficult to prepare a liquid composition such as ink for forming a heat seal layer by a coating method such as printing.

(Titanium oxide)
The heat sealant contains titanium oxide. Titanium oxide is a component for exhibiting concealment. The mass ratio of the resin component content ((A) + (B)) to the titanium oxide content (C) is ((A) + (B)) :( C) = 10: 90 to 70: It is 30, preferably 20:80 to 60:40. As described above, since the resin component contains chlorinated PP and chlorinated EVA in a predetermined ratio, a relatively large amount of titanium oxide can be contained, and sufficient concealment can be ensured. If the amount of titanium oxide with respect to the resin component is too small, the hiding property is insufficient. On the other hand, if the amount of titanium oxide with respect to the resin component is too large, the heat seal strength is insufficient.

(Medium)
The heat sealant is a liquid composition such as ink for coating and forming a heat seal layer by dissolving or dispersing a resin component or a solid content such as titanium oxide in a medium such as an appropriate organic solvent. be able to. The type of organic solvent that dissolves or disperses such a resin component or the like is not particularly limited. As the organic solvent, for example, ketones, esters, glycol esters, aromatic hydrocarbons and the like can be used. Specific examples of ketones include methyl ethyl ketone and methyl isobutyl ketone. Specific examples of the esters include ethyl acetate, normal propyl acetate, isopropyl acetate, isobutyl acetate and the like. Specific examples of glycol esters include propylene glycol methyl ether acetate and the like. Specific examples of aromatic hydrocarbons include toluene and xylene. From the viewpoint of solubility of chlorinated polypropylene, it is preferable to use toluene. Further, from the viewpoint of drying adjustment and viscosity adjustment, it is preferable to use a combination of a plurality of types of organic solvents.

The content of the organic solvent in the heat sealant used as the ink is not particularly limited, and for example, the viscosity may be appropriately set so as to be suitable for a coating method such as printing. Specifically, the content of the organic solvent in the heat sealant is preferably 20 to 90% by mass, and more preferably 30 to 85% by mass.

(Use as two-component ink)
The heat sealant can be used as a so-called two-component liquid composition (ink) in combination with a curing agent. As the curing agent, for example, an isocyanate-based curing agent such as polyisocyanate can be used. Here, it is assumed that the color ink layer arranged adjacent to the heat seal layer is formed of, for example, urethane-based color ink. In this case, if the base material layer forming the color ink layer is polypropylene, it is generally difficult to improve the adhesion between the color ink layer and the base material layer. Therefore, by forming a heat seal layer using a heat sealant as a two-component ink as described above, a color ink layer formed of urethane-based color inks arranged adjacent to each other and a group composed of polypropylene. This is preferable because the adhesion to the material layer can be improved. It is considered that this is because the curing agent such as polyisocyanate contained in the heat seal layer is transferred to the adjacent color ink layer.

(Monoisocyanate compound)
When the heat sealant is used as a two-component liquid composition (ink) in combination with the curing agent, the polyisocyanate used as the curing agent easily reacts with the reaction point in the resin component contained in the heat sealant. Therefore, when the heat sealant (first liquid) and the polyisocyanate (second liquid) are mixed, the obtained mixture tends to gel over time, and the pot life may be shortened. Therefore, by including the monoisocyanate compound in the heat sealant, even when the heat sealant is used as a two-component ink, it becomes difficult for a gelled product to be formed at the time of mixing, and the pot life is prolonged. It is preferable because it can be used. It is considered that this is because the reaction points in the resin component contained in the heat sealant are consumed (crushed) by reacting with the monoisocyanate compound, and the reaction with the polyisocyanate added thereafter is suppressed. Be done.

It is assumed that the color ink layer arranged adjacent to the heat seal layer is formed of, for example, a so-called two-component urethane color ink which is a combination of a urethane-based color ink and a curing agent such as polyisocyanate. do. In this case, the curing agent in the urethane color ink moves to the adjacent heat seal layer and reacts with the reaction point in the resin component contained in the heat seal agent constituting the heat seal layer. As a result, the heat resistance of the heat seal layer may increase and the heat seal property may decrease. Therefore, as described above, the heat sealant contains the monoisocyanate compound, and the reaction points in the resin component are consumed in advance by the monoisocyanate compound, so that the transferred polyisocyanate reacts with the resin component. The reaction with the point can be suppressed. As a result, even when the color ink layer is formed by the two-component urethane color ink, the heat sealability of the heat seal layer arranged adjacent to the color ink layer can be maintained in an excellent state.

The monoisocyanate compound may be a compound having one isocyanate group in its molecular structure capable of reacting with a reaction site in the resin component. Examples of the monoisocyanate compound include methyl isocyanate, ethyl isocyanate, propyl isocyanate, n-butyl isocyanate, t-butyl isocyanate, isobutyl isocyanate, pentyl isocyanate, neopentyl isocyanate, 2-ethyl-hexyl isocyanate, phenyl isocyanate, and trill isocyanate. Examples thereof include 1-naphthyl isocyanate, 2-naphthyl isocyanate, m-isopropenyl-α, α-dimethylbenzyl isocyanate, 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl acrylate, and octadecyl isocyanate. Of these, m-isopropenyl-α, α-dimethylbenzyl isocyanate, 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl acrylate, and octadecyl isocyanate are preferable because they are industrially produced and easily available. Further, in consideration of cost, m-isopropenyl-α and α-dimethylbenzyl isocyanate are more preferable.

The content of the monoisocyanate compound in the heat sealant is preferably 0.01 to 3.0% by mass, preferably 0.05 to 2.5% by mass, based on the total of the components other than the monoisocyanate compound. It is more preferably 0.1 to 2.0% by mass, and most preferably 0.15 to 1.5% by mass. If the content of the monoisocyanate compound is less than 0.01% by mass, the effect may be insufficient. On the other hand, if the content of the monoisocyanate compound is more than 3.0% by mass, the heat-sealing layer to be formed tends to be sticky, and blocking may easily occur when laminating or winding a product such as an insert film.

(Other ingredients)
In addition to the above components, the heat sealant may further contain components (other components) that can be contained in a general heat sealant for in-mold molding. Examples of other components include pigments for coloring, resin beads, slip agents, dispersants, anti-settling agents, anti-blocking agents, antistatic agents, flame retardants and the like. It is preferable to include a coloring pigment in the heat sealant because the adhesion between the formed heat seal layer and the adjacent color ink layer or the main body of the molded product is improved. The reason why the adhesion is improved by containing the pigment is not necessarily clear, but it is presumed that it is because an appropriate uneven structure derived from the pigment particles is formed in the heat seal layer.

<Insert film>
FIG. 1 is a partial cross-sectional view schematically showing an embodiment of the insert film of the present invention. The insert film 10 of the present embodiment is a film for in-mold molding that is arranged in a state of being adhered to the surface of the molded body body, and the base material layer 2, the color ink layer 4, and the heat seal layer 6 are laminated in this order. It is a laminated film. The heat-sealing layer 6 is a layer containing the above-mentioned heat-sealing agent, and is preferably a layer substantially composed of the above-mentioned heat-sealing agent.

The base material layer 2 is formed of, for example, a general resin film or sheet used as a base material layer of an insert film for in-mold molding such as an in-mold label. The base material layer can be formed of, for example, a biaxially stretched polypropylene (OPP) film. The thickness of the base material layer is not particularly limited, and may be, for example, about 10 to 100 μm, preferably about 30 to 70 μm.

The color ink layer 4 is a layer arranged between the base material layer 2 and the heat seal layer 6, and is a layer on which a desired pattern (design) is formed by general-purpose color ink. The color ink layer can be formed by applying a general-purpose color ink on the surface of the base material layer using, for example, a printing machine such as a gravure multicolor printing machine.

The heat seal layer 6 is a layer that can be formed by applying the above-mentioned heat seal agent and drying it if necessary. Similar to the color ink layer described above, the heat seal layer is a liquid composition obtained by diluting a heat sealant or a heat sealant on the surface of the color ink layer using, for example, a printing machine such as a gravure multicolor printing machine. It can be formed by applying ink). The thickness of the heat seal layer is not particularly limited, and may be, for example, about 1 to 10 μm, preferably 2 to 5 μm.

Since the heat seal layer 6 is a layer formed by the above-mentioned heat seal agent, it contains a relatively large amount of titanium oxide. Therefore, sufficient concealment is exhibited, and the design of the color ink layer 4 as seen from the base material layer 2 can be improved. Further, the heat seal layer 6 exhibits sufficient heat seal strength while containing a large amount of titanium oxide. Therefore, by using the insert film 10 of the present embodiment, it is possible to manufacture an in-mold molded product having excellent design and high reliability.

The insert film 10 may include a matte ink layer 8 laminated on the base material layer 2. By laminating the matte ink layer 8 on the base material layer 2, an insert film such as an in-mold label capable of producing an in-mold molded product having a matte surface can be obtained. Similar to the color ink layer described above, the matte ink layer can be formed by applying a general-purpose matte ink on the surface of the base material layer using, for example, a printing machine such as a gravure multicolor printing machine. ..

The insert film may be processed into a desired shape by performing shape processing such as cutting or punching, if necessary. Further, by cutting or the like, the shape can be processed into an in-mold label for in-mold molding or the like.

<In-mold molded body>
FIG. 2 is a partial cross-sectional view schematically showing an embodiment of the in-mold molded product of the present invention. The in-mold molded body 50 of the present embodiment includes a molded body body 20 and the above-mentioned insert film 10 arranged on the surface of the molded body body 20. Then, the insert film 10 is arranged in a state where the heat seal layer 6 is adhered to the surface of the molded body body 20.

As described above, the heat seal layer 6 constituting the insert film 10 contains a relatively large amount of titanium oxide. Therefore, the heat-sealing layer 6 exhibits sufficient hiding power, and the color ink layer 4 seen from the base material layer 2 is excellent in design. Further, the heat seal layer 6 exhibits sufficient heat seal strength while containing a large amount of titanium oxide. Therefore, the in-mold molded product 50 of the present embodiment is excellent in design and product reliability.

The in-mold molded product can be manufactured according to a conventionally known in-mold molding method, except that the above-mentioned insert film is used. For example, an insert film (in-mold label) having a heat-sealing layer and a color ink layer having a desired design is inserted into a mold. The insert film is inserted into the mold in a direction in which the heat seal layer is in contact with the molten resin. After that, if the molten resin is introduced into the mold according to a conventional method, an in-mold molded product such as a container in which the molded product main body and the label are integrated can be obtained.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In addition, "part" and "%" in Examples and Comparative Examples are based on mass unless otherwise specified.

<Preparation of heat sealant (ink)>
( Reference example 1)
Toluene solution of chlorinated PP (trade name "Supercron 1026", manufactured by Nippon Paper Industries, chlorine content: 26.0%, solid content: 20%) 24 parts, toluene solution of chlorinated EVA (trade name "Supercron B") , Nippon Paper Industries, Chlorine content: 26.5%, Solid content: 20%) 24 parts, 22 parts titanium oxide, and 30 parts toluene were mixed according to a conventional method to prepare a heat sealant (ink). The mass ratio of the chlorinated PP content (A) of the prepared heat sealant to the chlorinated EVA content (B) was (A) :( B) = 50:50. The mass ratio of the resin component content ((A) + (B)) to the titanium oxide content (C) is ((A) + (B)) :( C) = 30: 70. there were.

( Reference Examples 2 to 5, Examples 6 to 10, Comparative Examples 1 to 4)
A heat sealant (ink) was prepared in the same manner as in Reference Example 1 above, except that each component was blended so as to have the composition (unit: part) shown in the upper part of Tables 1-1 and 1-2. .. Mass ratio of the prepared heat sealant chlorinated PP content (A) to chlorinated EVA content (B) ((A): (B)), resin component content ((A) + The mass ratio of (B)) to the titanium oxide content (C) (((A) + (B)) :( C)) and the content (%) of the monoisocyanate compound are shown in Table 1-1 and It is shown in the middle of 1-2. Examples of the monoisocyanate compound include m-isopropenyl-α, α-dimethylbenzyl isocyanate (manufactured by Ornex Japan) (Examples 6 to 8), n-butyl isocyanate (manufactured by Chuo Kasei Seisakusho) (Example 9). And phenylisocyanate (manufactured by Chuo Kaseihin Co., Ltd.) (Example 10) were used, respectively. The content of the monoisocyanate compound is a ratio (%) based on the total of the components other than the monoisocyanate compound. In addition, in Comparative Example 3, it could not be converted into ink.

<Coating of heat sealant (ink)>
A printing ink was prepared by diluting 100 parts of each prepared heat sealant with 30 parts of a diluting solvent (toluene / MEK = 1/1). A biaxially stretched polypropylene (OPP) film (trade name "FOS-BT", manufactured by Futamura Chemical Co., Ltd., using a gravure proofing machine equipped with a net gravure printing plate having a number of lines of 175 lines per inch and a depth of 30 μm. A printing ink prepared to a thickness of 50 μm) was applied to obtain a printed matter on which a heat seal layer having a thickness of 53 μm was formed.

<Evaluation>
(Heat seal strength)
A laminated film of unstretched polypropylene (CPP) and OPP was prepared. The printed matter and the bonded film were laminated so that the heat seal layer of the printed matter and the CPP of the bonded film were in contact with each other. Using a heat seal tester (trade name "TP-701S", manufactured by Tester Sangyo Co., Ltd.), heat seal was performed under the conditions shown below, and then the test piece was cut into 1 inch width to prepare a test piece.
[Heat seal conditions]
・ Temperature: 150 ℃, 190 ℃
・ Pressure: 1kgf / cm ²
・ Time: 1 second

Using a T-type peel tester, the heat-sealed portion of the prepared test piece was pulled at a peeling speed of 300 mm / min. Using a tensile strength tester (trade name "Strograph EL", manufactured by Toyo Seiki Seisakusho Co., Ltd.), the strength (heat seal strength) at the time of peeling of the heat-sealed portion was measured. The measurement results are shown in Tables 1-1 and 1-2.

(OD value)
The OD value of the printed matter was measured using a high-concentration transmission densitometer (trade name "361T (V)", manufactured by Video Jet X-Light Co., Ltd.). The results are shown in Tables 1-1 and 1-2.

(Presence / absence of gelation)
An isocyanate-based curing agent (trade name "Ramic B Hardener", manufactured by Dainichiseika Kogyo Co., Ltd.) was added to each heat sealant (ink) in an amount of 5%. An idling test was conducted using a rotary printing press while adding a diluting solvent as appropriate. After 6 hours, the state of the ink in the ink pan (presence or absence of gelation) was visually confirmed. The results are shown in Tables 1-1 and 1-2.

(Presence / absence of blocking)
The printed matter was cut to prepare a test piece having a size of 4 cm × 4 cm. The heat-sealed layer of the test piece and an OPP film (trade name "FOS-BT", manufactured by Futamura Chemical Co., Ltd., thickness: 50 μm) cut to the same size were superposed. After leaving the test piece and the OPP film at 40 ° C. for 16 hours while applying a load of 0.5 kg / cm ² , the presence or absence of resistance (blocking) when peeling off the test piece and the OPP film was confirmed. The results are shown in Tables 1-1 and 1-2.

By using the heat sealant of the present invention, it is possible to provide an insert film such as an in-mold label which is excellent in design and can produce a highly reliable in-mold molded product.

2: Base material layer 4: Color ink layer 6: Heat seal layer 8: Matte ink layer 10: Insert film 20: Mold body 50: In-mold molded body

Claims (6)

A heat sealant for in-mold molding containing a resin component and titanium oxide.
The resin component contains chlorinated polypropylene and chlorinated ethylene-vinyl acetate copolymer.
The mass ratio of the content (A) of the chlorinated polypropylene to the content (B) of the chlorinated ethylene-vinyl acetate copolymer in the resin component is (A) :( B) = 30: 70 to 95: 5 and
The mass ratio of the content of the resin component ((A) + (B)) to the content of titanium oxide (C) is ((A) + (B)) :( C) = 10: 90 to 70:30 der is,
Further containing a monoisocyanate compound,
The content of the mono-isocyanate compound, based on the total of the components other than the mono-isocyanate compound, a heat-sealing material Ru 0.01 to 3.0% by mass. The heat sealant according to claim 1, which is used as a two-component liquid composition in combination with a curing agent. The first aspect of claim 1, which is used to form a heat seal layer arranged adjacent to a color ink layer formed of a two-component urethane color ink which is a combination of a urethane-based color ink and a curing agent. Heat sealant. An insert film for in-mold molding that is placed in a state of being adhered to the surface of the molded body.
An insert film which is a laminated film in which a base material layer, a color ink layer, and a heat seal layer containing the heat seal agent according to claim 1 or 2 are laminated in this order. The insert film according to claim 4, wherein the color ink layer is formed of a two-component urethane color ink which is a combination of a urethane-based color ink and a curing agent. The insert film according to claim 4 or 5 , which is provided with a molded body and an insert film arranged on the surface of the molded body.
An in-mold molded product in which the insert film is arranged with the heat seal layer adhered to the surface of the molded product body.

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