WO2014112389A1 - In-mold label, resin molded article and method for producing same - Google Patents

Abstract

Provided is an in-mold label which has both excellent adhesiveness and excellent transparency. An in-mold label which is provided with at least a base layer and a seal layer that is laminated on the surface of the base layer. The base layer has an internal haze of 0.1-20% as determined in accordance with JIS-K-7136; and the seal layer contains an olefin resin, and has a melting heat quantity of 10-55 J/g and an average refractive index of 1.4-1.6 under specific conditions.

Description

In-mold label, resin molded product, and method for producing the same

The present invention relates to an in-mold label, a resin molded product, and a manufacturing method thereof.

Conventionally, a technique for integrally molding a resin molded product with a label is known. According to said technique, after inserting a blank or a label into a metal mold | die beforehand, resin is shape | molded in the said metal mold | die by methods, such as injection molding, hollow molding, differential pressure molding, and foam molding. Thereby, the resin molded product with a label which the label affixed on the resin molding is obtained. The above label is called an in-mold label.

As an in-mold label, a transparent in-mold label using a transparent base material having a low elastic modulus, an in-mold label having an adhesive layer formed of a resin having a low heat of fusion, and the like have been studied (Patent Documents 1 to 4). reference).
[Prior art documents]
[Patent Literature]
[Patent Document 1] JP 58-069015 [Patent Document 2] JP 02-217223 [Patent Document 3] JP 04-004130 [Patent Document 4] JP 2010-168117

However, the conventional in-mold label has room for improvement in terms of achieving both excellent adhesion and transparency.

Therefore, an object of the present invention is to provide an in-mold label excellent in adhesiveness and transparency. Another object is to provide a resin molded product including the in-mold label and a manufacturing method thereof.

As a result of intensive studies, the present inventors have found that the above object can be achieved by in-mold molding using a label having a specific structure.

In the first aspect of the present invention, at least a base material layer and a sealing layer laminated on the surface of the base material layer are provided, and the base material layer has an internal portion measured according to JIS-K-7136. The haze is 0.1 to 20%, the seal layer contains an olefin resin, the heat of fusion is 10 to 55 J / g, and the preform is heated to 95 ° C. An in-mold label having an average refractive index of 1.50 to 1.60 when measured at 23 ° C. after cooling to 50 ° C. in 15 seconds after introduction of compressed air and in-mold molding is provided.

In the second aspect of the present invention, at least a base material layer and a seal layer in a state of being laminated on the surface of the base material layer are provided, and the base material layer has an internal portion measured according to JIS-K-7136. The haze is 0.1 to 20%, the seal layer contains an olefin resin, the heat of fusion is 10 to 55 J / g, and the preform is heated to 95 ° C. After in-mold molding with introduction of compressed air, an in-mold label having a crystallinity of 0 to 50% when measured at 23 ° C. after cooling to 50 ° C. in 15 seconds is provided.

In the third aspect of the present invention, at least a base material layer and a sealing layer laminated on the surface of the base material layer are provided, and the base material layer has an internal portion measured according to JIS-K-7136. The haze is 0.1 to 20%, the seal layer contains an olefin resin, the heat of fusion is 10 to 55 J / g, and the preform is heated to 95 ° C. An in-mold label is provided which is cooled to 50 ° C. in 15 seconds after introduction of compressed air and then cooled to 50 ° C. and has an adhesive strength of 100 to 1000 gf / 15 mm when measured at 23 ° C. The

According to a fourth aspect of the present invention, there is provided a resin molded product comprising a resin molded product and the in-mold label of each of the above-described embodiments attached to the resin molded product, the measurement being performed according to JIS-K-7136. Among the resin molded products, there is provided a resin molded product in which the difference in haze between the bonded part of the in-mold label and the non-sticked part is 20% or less.

According to a fifth aspect of the present invention, there is provided a method for producing a resin molded product according to the above aspect, wherein the in-mold label is disposed inside the molding machine when the resin molding is molded by the molding machine. However, the method of manufacturing the resin molded product including the step affixed on the resin molding is provided.

Note that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

It is sectional drawing of the in-mold label which concerns on one Embodiment of this invention. It is sectional drawing of the in-mold label which concerns on other embodiment of this invention. It is sectional drawing of the in-mold label which concerns on other embodiment of this invention. It is a perspective view which shows the specific example of the resin molded product which concerns on one Embodiment of this invention.

Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

In this specification, “haze” is a cloud point measured according to JIS-K-7136. The “internal haze” includes a base material layer or the like in order to eliminate light scattering due to unevenness of the surface of the base material layer when measuring the haze of the base material layer according to JIS-K-7136. It means a value obtained by measuring only both sides of a sample of the laminate in liquid paraffin and extracting only light scattering inside the base material layer. In addition, JIS-K-7136, more specifically JIS-K-7136: 2000, is named “Plastics-Determination of haze for transparent materials” and is a compatible international standard. Is ISO 14782 (1999). In addition, the method and conditions performed in the below-mentioned Example are employ | adopted for the other measuring method and conditions regarding said haze and internal haze. However, the measurement methods and conditions for haze and internal haze are merely described for the purpose of uniquely defining the numerical ranges of haze and internal haze, and do not limit the embodiments described below.

In addition, in this specification, the “main component” means a component having a content of 50% by mass or more in the total content (100% by mass) of the contained components.

[1. In-mold label]
FIG. 1 is a cross-sectional view of an in-mold label according to an embodiment of the present invention. The in-mold label 1 includes at least a base material layer 2 and a seal layer 3 in a state of being laminated on the surface of the base material layer 2. In the embodiment shown in FIG. 1, the in-mold label 1 is a resin film having a laminated structure of a base material layer 2 and a seal layer 3. The in-mold label 1 is formed inside the molding machine, more specifically, when the resin is molded in-mold using a molding machine such as a mold by a blow molding technique such as direct blow molding or stretch blow molding. Arranged on the inner wall of the machine. Thereby, the in-mold label 1 sticks to the resin molded body during in-mold molding, and a resin molded product is obtained.
In the following, the base material layer 2 and the seal layer 3 will be described in detail.

<1-1. Base material layer>
The base material layer 2 serves as a support for the in-mold label 1. The base material layer 2 gives the in-mold label 1 rigidity (sometimes referred to as stiffness) that allows handling such as printing and insertion into a molding machine.

The base material layer 2 has an internal haze in the range of 0.1 to 20%. If the internal haze is within the above range, the in-mold label 1 having excellent transparency can be obtained. Further, since the transparency of the in-mold label 1 is further improved, the internal haze is preferably 1 to 16%, more preferably 5 to 12%.

The material constituting the base material layer 2 is not particularly limited, and examples thereof include resins, antioxidants, and ultraviolet stabilizers. Although it does not restrict | limit especially as resin contained in the base material layer 2, A thermoplastic resin can be illustrated. The base material layer 2 preferably contains a resin as a main component, and more preferably contains a thermoplastic resin as a main component.

The thermoplastic resin is not particularly limited, and examples thereof include olefin resins, polyester resins, polyvinyl chloride resins, polyamide resins, polystyrene resins, polycarbonate resins, and ionomer resins. Examples of olefin resins include polypropylene resins, polymethyl-1-pentene, and copolymers of ethylene and cyclic olefins (such as ethylene / cyclic olefin copolymers. The same applies to other copolymers. And the like.) May be exemplified. Examples of the polyester resin include polyethylene terephthalate resin and polybutylene terephthalate resin. Examples of polyamide resins include nylon-6, nylon-6,6, nylon-6,10, nylon-6,12 and the like.

Among the above thermoplastic resins, thermoplastic resins having a melting point in the range of 130 to 280 ° C. and a crystallinity in the range of 0 to 50% are preferable. Thereby, shaping | molding of the resin film provided with the base material layer 2 whose internal haze is in said range becomes easy. Examples of such thermoplastic resins include polypropylene resins and polyethylene terephthalate resins.

The resin constituting the substrate layer 2 may be a single type or a mixture of two or more types. The resin is preferably one selected from the thermoplastic resins specifically exemplified above. Thereby, more excellent transparency is obtained.
More specifically, the base material layer 2 preferably includes at least one of a polypropylene-based resin and a polyester-based resin, more preferably includes at least one of a polypropylene-based resin and a polyethylene terephthalate resin. More preferably, it consists of a terephthalate resin.

Further, the melting point of the thermoplastic resin that can be contained in the base material layer 2 is preferably 15 ° C. or higher than the melting point of the olefin resin that can be contained in the seal layer 3. Among such thermoplastic resins, a polypropylene resin is preferable. By the base material layer 2 containing a polypropylene resin, the base material layer 2 excellent in transparency, heat resistance, and durability can be obtained. Moreover, the cost of the base material layer 2 can be reduced.

Examples of the polypropylene resin contained in the substrate layer 2 include propylene homopolymers and propylene / α-olefin copolymers that exhibit isotactic or syndiotactic stereoregularity. The propylene / α-olefin copolymer preferably contains propylene as a main component. Examples of the α-olefin constituting the propylene / α-olefin copolymer include ethylene, butene-1, hexene-1, heptene-1,4-methylpentene-1. The propylene / α-olefin copolymer may be any of binary, ternary and quaternary systems. The propylene / α-olefin copolymer may be a random copolymer or a block copolymer.

The base material layer 2 may contain an additive as necessary within the range in which the transparency is not impaired in addition to the above resin. Specific examples of the additive include an antioxidant, an ultraviolet stabilizer, and a nucleating agent.

Examples of the antioxidant include sterically hindered phenol-based, phosphorus-based, and amine-based antioxidants. The content of the antioxidant is, for example, in the range of 0.001 to 1% by mass with respect to the total content (100% by mass) of the constituent components of the base material layer 2. Examples of the ultraviolet stabilizer include sterically hindered amine-based, benzotriazole-based, and benzophenone-based light stabilizers. The content of the ultraviolet stabilizer is, for example, in the range of 0.001 to 1 mass% with respect to the total content (100 mass%) of the constituent components of the base material layer 2.

The thickness of the base material layer 2 is not particularly limited, but is preferably 20 to 200 μm. When the thickness of the base material layer 2 is 20 μm or more, the generation of wrinkles in the in-mold label 1 can be effectively prevented even when printing on the in-mold label 1. Moreover, it becomes easy to fix the in-mold label 1 at an appropriate position in the molding machine. Thereby, the position shift of the in-mold label 1 can be prevented. When the thickness of the base material layer 2 is 200 μm or less, it is possible to effectively prevent the strength from decreasing at the boundary portion of the in-mold label 1 of the obtained resin molded product. Thereby, the fall of the drop-proof strength of a resin molded product, etc. can be prevented effectively. The thickness of the base material layer 2 is more preferably 40 to 150 μm. In this case, the above effect is further improved.

The shape of the base material layer 2 is, for example, a film shape. The base material layer 2 is preferably an unstretched film or a stretched film stretched in at least a uniaxial direction.

<1-2. Molding of base material layer>
The base material layer 2 constituting the in-mold label 1 of the present embodiment can be manufactured by various methods known to those skilled in the art and combinations thereof. An in-mold label 1 manufactured by any method is included in this embodiment as long as the conditions described in this specification are satisfied.

The method for forming the base material layer 2 is not particularly limited, and examples thereof include a cast molding method, an inflation molding method, a rolling method, and a calendar molding method. The cast molding method is a method of extruding a molten resin into a sheet using a single layer T-die connected to a screw type extruder. The inflation molding method is a method of extruding a molten resin into a tube shape using an O-die connected to a screw type extruder.

The base material layer 2 itself may have a single layer structure or a multilayer structure of two or more layers. When the base material layer 2 has a multilayer structure, gas barrier properties and the like are improved.

In addition, the matter demonstrated about shaping | molding of the base material layer 2 is applicable similarly to the below-mentioned intermediate | middle layer and printable layer.

<1-3. Seal layer>
The seal layer 3 included in the in-mold label 1 of the present embodiment is laminated on the surface of the base material layer 2 to adhere the in-mold label 1 and the resin molded body. Since the sealing layer 3 adheres the in-mold label 1 and the resin molded body when the resin molded product is molded, the sealing layer 3 has a good heat sealing performance.

The seal layer 3 contains an olefin resin. Further, the physical properties of the sealing layer 3 such as the heat of fusion, the recrystallization temperature, and at least one of the average refractive index and crystallinity under specific conditions are adjusted to a specific range. Thereby, the in-mold label 1 excellent in adhesiveness and transparency is obtained.

The heat of fusion of the olefin resin contained in the seal layer 3 or the seal layer 3 is 10 to 55 J / g, preferably 20 to 55 J / g, more preferably 30 to 54 J / g, More preferably, it is ˜50 J / g.
When the heat of fusion is within the above range, in the molding method requiring adhesion at a relatively low temperature (for example, 90 to 110 ° C., preferably 95 to 110 ° C.) as in stretch blow molding, The mold label 1 is provided with sufficient adhesive strength with the resin molding.
“The amount of heat of fusion” in the present specification is measured using a differential scanning calorimeter manufactured by SII Technology, and describes the area of the endothermic peak when each label is heated and cooled in a furnace.

When a material that becomes white turbid when recrystallized is used as the seal layer 3 or the olefin resin contained in the seal layer 3, the recrystallization temperature of the seal layer 3 or the olefin resin is the molding temperature of the resin molding. It is preferable that it is above, and it is more preferable that it is higher than the molding temperature. As a result, when the resin molded body is molded, the constituent components of the seal layer 3 are not recrystallized, and thus the cloudiness of the seal layer 3 after molding can be prevented. As a result, the transparency of the in-mold label 1 after molding becomes excellent. In the above case, the recrystallization temperature is preferably 40 to 110 ° C., more preferably 45 to 105 ° C., and further preferably 50 to 100 ° C.

When polyethylene terephthalate (sometimes referred to as PET) is used as the resin molding, the temperature of the preform before molding is, for example, 90 to 110 ° C., and preferably 95 to 110 ° C. Therefore, a material having a recrystallization temperature equal to or higher than the molding temperature of the resin molding (more preferably higher than the molding temperature of the resin molding) is used as the sealing layer 3 or the olefin resin contained in the sealing layer 3. Thus, the sealing layer 3 can be prevented from becoming clouded.

On the other hand, as the olefin resin contained in the seal layer 3 or the seal layer 3, when a material that does not become cloudy even when recrystallized is used, or even when it becomes cloudy when recrystallized, the transparency of the in-mold label 1 is high in quality. When a material that does not deteriorate is used, the recrystallization temperature is not particularly limited. In this case, the recrystallization temperature is, for example, 40 to 110 ° C.
The value obtained by measuring with a differential scanning calorimeter (DSC) is adopted as the “recrystallization temperature” in this specification.

The average refractive index of the olefin resin contained in the seal layer 3 or the seal layer 3 is 50 in 15 seconds after heating the preform to 95 ° C., introducing 2.5 MPa of compressed air, and performing in-mold molding. It may be 1.4 to 1.6 under specific conditions of cooling to 0 ° C. and measuring at room temperature (23 ° C.). The average refractive index under the specific conditions is preferably 1.45 to 1.57, and more preferably 1.5 to 1.55.

When the average refractive index is within the above range, the average refractive index of the in-mold label 1 including the seal layer 3 and the average refractive index of a resin molded body in which, for example, PET is mainly used are the same or approximate values. Become. Thereby, even after shaping | molding, the transparency of the sticking part of the in-mold label 1 becomes excellent. In addition, since the transparency of the in-mold label 1 sticking part of the resin molded product is equivalent to the transparency of the non-sticking part, there is no difference between the sticking part and the non-sticking part. The boundary becomes difficult to see. As a result, the appearance of the resin molded product is improved.
As the “average refractive index” in the present specification, a value obtained by measuring with an Abbe refractometer is adopted. In addition, you may replace said specific conditions with the more simplified conditions of measuring after cooling a preform to 95 degreeC and cooling to 50 degreeC in 15 seconds.

The degree of crystallinity of the olefin resin contained in the seal layer 3 or the seal layer 3 is 50 in 15 seconds after heating the preform to 95 ° C., introducing 2.5 MPa of compressed air, and performing in-mold molding. Under the specific conditions of cooling to 0 ° C. and measuring at room temperature (23 ° C.), it may be 0 to 50%, preferably 10 to 45%, more preferably 15 to 40%. When the crystallinity is within the above range, it is possible to prevent the average refractive index of the seal layer 3 from being lowered due to crystallization. Thereby, even after molding, not only the transparency of the non-sticking part of the in-mold label 1 in the resin molded product but also the transparency of the sticking part is excellent.
In addition, you may replace said specific conditions with the more simplified conditions of measuring after cooling a preform to 95 degreeC and cooling to 50 degreeC in 15 seconds.

As the “crystallinity” in the present specification, a value measured by the method (X-ray diffraction method) used in the examples described later is adopted. In addition, when the seal layer 3 contains two or more kinds of components in excess of the detection limit, or when the crystallization state of the olefin resin is complicated, the crystallinity of the seal layer 3 or the olefin resin is determined by X-ray diffraction. It may be measured by an alternative method. As a case where the crystallization state of the olefin resin is complicated, a case where the crystallization state of the olefin resin is multiphase can be exemplified.

An alternative to the X-ray diffraction method is a method using a differential scanning calorimetry (DSC) method. The procedure of the method will be described. First, the seal layer 3 or the olefin resin is left at room temperature for 12 hours. Subsequently, the sample is cut into 10 mg samples and heated at a rate of 10 ° C./min from 30 to 300 ° C. in a nitrogen atmosphere using the DSC method. And the total calorie | heat amount of the exothermic peak of each component at the time of temperature rising and the total calorie | heat amount of an endothermic peak are calculated | required, and the crystallinity D is computed by the following formula | equation.
Crystallinity D (%) = [total heat of endothermic peak (J / g) −total heat of exothermic peak (J / g)] / [total theoretical heat of fusion (J / g)] × 100
In addition, the sum total of the theoretical heat of fusion in the said formula is the sum total of the value which multiplied the content rate and theoretical heat of fusion of each component.

When any one of the physical properties such as the heat of fusion, the average refractive index, and the crystallinity satisfies the above numerical conditions, the adhesiveness and transparency of the in-mold label 1 are improved. Especially, it is preferable that at least one of an average refractive index and a crystallinity degree satisfy | fills said numerical condition. More preferably, the heat of fusion and at least one of the average refractive index and the degree of crystallinity satisfy the above numerical conditions. It is preferable that the heat of fusion and the average refractive index or crystallinity satisfy the above numerical conditions.
In the case of using a material that becomes clouded when recrystallized as the olefin resin contained in the seal layer 3 or the seal layer 3, in addition to the above preferred physical properties, the recrystallization temperature also satisfies the above numerical conditions. Is more preferable. Thereby, the in-mold label 1 which was further excellent in adhesiveness and transparency is obtained.

It is preferable that each of the above physical properties is adjusted to the specific range as a whole of the constituent components of the seal layer 3. Furthermore, it is more preferable that the olefin resin contained in the seal layer 3 has a value within the above specific range for at least one of the above physical properties. In addition, in this embodiment, although the case where a specific physical property is adjusted to said specific range among each physical property is demonstrated in detail, also when other physical properties are adjusted to said specific range, It can be implemented similarly.

Note that the measurement methods and conditions for the above physical properties and the specific conditions for the degree of crystallinity are merely conditions for unambiguously defining the numerical range of each physical property, and the in-mold label 1 of the present embodiment and this It does not limit each layer which comprises. Moreover, it is preferable to shape | mold said resin molded product by the stretch blow method.

Hereinafter, the olefin resin contained in the seal layer 3 and the olefin resin emulsion among the olefin resins will be described in detail.

(Olefin resin)
Examples of the olefin resin contained in the seal layer 3 include olefin homopolymers, olefin copolymers, copolymers formed from olefins and other comonomers.

Specific examples of the olefin include ethylene and propylene. Among these, ethylene is preferable because an appropriate degree of crystallinity is easily obtained and heat sealing performance is easily adjusted. Moreover, since it is easy to enlarge the adhesive strength of various resin molded products and the in-mold label 1, the olefin resin contained in the seal layer 3 may be a copolymer formed from ethylene and other comonomers. preferable. The content of the other comonomer in the copolymer is not particularly limited, but is preferably 5 to 50% by mass with respect to the total content (100% by mass) of the copolymer. In this case, it becomes easy to obtain an appropriate degree of crystallinity, and it becomes easy to adjust the heat sealing performance. Furthermore, the melt flow rate of the olefin resin is preferably 20 g / 10 min or more. In this case, an aqueous dispersion described later is easily obtained.

The other comonomer is not particularly limited, and examples thereof include alkene (carbon number is preferably 2 to 8), vinyl acetate, acrylic acid, methacrylic acid, and acrylic acid alkyl ester (alkyl group having 1 to carbon atoms). 8), methacrylic acid alkyl ester (the alkyl group preferably has 1 to 8 carbon atoms), maleic anhydride and the like.

Specific examples of copolymers formed from ethylene and other comonomers include ethylene / hexene copolymers, ethylene / vinyl acetate copolymers, ethylene / acrylic acid copolymers, ethylene / methacrylic acid copolymers, ethylene・ Metal salt of methacrylic acid copolymer, ethylene / methacrylic acid / acrylic acid alkyl ester copolymer, ethylene, acrylic acid alkyl ester, maleic anhydride copolymer, and ethylene of these copolymers. Examples thereof include a copolymer containing carboxylic acid-modified ethylene modified with a carboxylic acid.

The metal constituting the metal salt is not particularly limited, and examples thereof include zinc (Zn), aluminum (Al), lithium (Li), potassium (K), and sodium (Na). Moreover, maleic acid modified ethylene etc. can be illustrated as carboxylic acid modified ethylene.

The olefin resin contained in the seal layer 3 preferably includes a copolymer containing at least one of vinyl acetate, acrylic acid, and methacrylic acid and ethylene as a comonomer among the above-mentioned copolymers. The copolymer may be a carboxylic acid-modified copolymer.
When the copolymer contained in the olefin-based resin contains at least one of vinyl acetate, acrylic acid, and methacrylic acid and ethylene as a comonomer, a relatively low temperature (for example, 90 to 110 ° C., as in stretch blow molding, Even in a molding technique that requires adhesion at 95 to 110 ° C.), the adhesive strength between the in-mold label 1 and the resin molded body is further excellent, and the in-mold label 1 after pasting is transparent. Thus, the sealing layer 3 having further improved properties can be obtained.

The olefin-based resin contained in the seal layer 3 may be a copolymer of ethylene and vinyl acetate (sometimes referred to as EVA), a copolymer of maleic acid-modified ethylene and vinyl acetate (sometimes referred to as maleic acid-modified EVA). ), A copolymer of ethylene and methacrylic acid (sometimes referred to as EMA), and a copolymer of ethylene, methacrylic acid, and alkyl acrylate (ethylene / methacrylic acid / acrylic acid ester copolymer) At least one of them may be included.
More specifically, the olefin resin contained in the seal layer 3 preferably contains at least one of a copolymer of ethylene and vinyl acetate, and a copolymer of maleic acid-modified ethylene and vinyl acetate. More preferably, it contains a modified ethylene / vinyl acetate copolymer. In this case, the adhesive strength between the resin molded body and the in-mold label 1 is further improved.

The content of vinyl acetate in the ethylene / vinyl acetate copolymer is not particularly limited, but is preferably 5 to 50% by mass with respect to the total content (100% by mass) of the copolymer. When the content is 5% by mass or more, the in-mold label 1 can be more strongly bonded to the resin molded body, and the transparency tends to be further improved. Moreover, since it is easy to melt | dissolve in a medium, manufacture of a carboxylic acid modified material becomes easy. On the other hand, when the content is 50% by mass or less, even when an olefin-based resin is used as the resin constituting the base material layer 2 and the resin molded body, the adhesiveness tends to be further improved.

The acid value in the copolymer of carboxylic acid-modified ethylene and vinyl acetate is preferably 1 to 60. When the acid value is 1 or more, an aqueous dispersion is easily obtained. On the other hand, when the acid value is 60 or less, water resistance and moisture resistance are more excellent.

A copolymer of carboxylic acid-modified ethylene and vinyl acetate can be produced by a known method. For example, as described in Japanese Patent Application Laid-Open No. 3-112836, an ethylene / vinyl acetate copolymer is first dissolved in an aromatic hydrocarbon such as toluene or xylene. Subsequently, lower alcohols such as methyl alcohol or ethyl alcohol are added, and a saponification reaction is performed using an alkali alcoholate catalyst in the presence of a specific amount of water. Subsequently, a saponified ethylene / vinyl acetate copolymer obtained by a saponification reaction, an unsaturated carboxylic acid such as maleic acid, fumaric acid, itaconic acid, citraconic acid, allyl succinic acid, mesaconic acid, and aconitic acid, and A copolymer of carboxylic acid-modified ethylene and vinyl acetate is obtained by reacting at least one selected from the group consisting of acid anhydrides and acid esters with a radical polymerization initiator.

Among the copolymers of carboxylic acid-modified ethylene and vinyl acetate, a maleic acid-modified ethylene / vinyl acetate copolymer obtained by a polymerization reaction using at least one of maleic acid and maleic anhydride is preferable.

The olefin-based resin may be composed of one or more of the above-mentioned olefin homopolymers and copolymers, and copolymers formed from olefins and other comonomers. .

Olefin-based resins can be used as needed so-called tackifiers, waxes, anti-blocking agents such as inorganic powder anti-blocking agents, organic slip agents, thermoplastic polyurethanes, thermoplastic polyesters, as long as transparency is not impaired. One or more selected from the group consisting of chlorinated polypropylene and chlorinated polyethylene may be further included. Among these, when the olefin resin contains at least one of thermoplastic polyurethane, thermoplastic polyester, chlorinated polypropylene, and chlorinated polyethylene, the cohesive strength and adhesive strength of the olefin resin are further improved.

Specific examples of the tackifier include rosin and derivatives thereof, terpene and derivatives thereof, petroleum resins, and hydrogenated products thereof. Specific examples of the waxes include paraffin wax, microcrystalline wax, carnauba wax, and Fisher tops wax. Specific examples of the inorganic powder-based antiblocking agent include silica, talc, and zeolite. Specific examples of the organic slip agent include erucic acid amide, oleic acid amide, and stearic acid amide.

(Coating fluid)
The seal layer 3 may be a coating layer obtained by coating and drying a coating liquid containing an olefin resin on the surface of the base material layer 2. The coating liquid containing the olefin resin is a solution in which at least one of the above-mentioned olefin homopolymer, olefin copolymer, and copolymer formed from olefin and other comonomers is dissolved in an organic solvent. Alternatively, it may be a dispersion containing an olefin resin emulsion in a state where they are dispersed in an aqueous medium.

Here, the in-mold label 1 may maintain a transparent state before and after being integrally formed with a resin molded body in a molding machine, and changes from an opaque state to a transparent state. May be.
More specifically, in one embodiment, the seal layer 3 of the in-mold label 1 is in a non-heated state (referred to as a state before integral molding), even after heating (referred to as a state after integral molding). .) Is also transparent. Examples of such a material for the seal layer 3 include olefin homopolymers, olefin copolymers, and copolymers formed from olefins and other comonomers.
In another embodiment, the sealing layer 3 of the in-mold label 1 is opaque in a non-heated state, but is transparent in a state after heating. In this case, it becomes easy to find defects in quality of the in-mold label 1 during printing. Examples of such a material for the seal layer 3 include a coating layer prepared using a coating solution containing the olefin resin emulsion.

Note that whether the seal layer 3 is transparent or opaque may be a subjective judgment result by the viewer of the in-mold label 1. The case where the internal haze of the sealing layer 3 is 50% or less may be “transparent”, and the case where it exceeds 50% may be “opaque”. Moreover, in said description, "heating" shows that the in-mold label 1 is heated at the time of shaping | molding of a resin molded product. However, the above description does not limit the heating conditions and molding conditions of the present embodiment.

(Olefin resin emulsion)
The in-mold label 1 using an olefin resin emulsion as the material for the seal layer 3 is opaque due to the emulsion particles, and has an advantage that it is easy to find defects in label quality during printing. Furthermore, in the resin molded product in which the in-mold label 1 using the olefin resin emulsion as the material of the seal layer 3 is adhered to the resin molded body, the olefin resin in the seal layer 3 is melted during the molding to form emulsion particles. Disappears, and the sealing layer 3 becomes more excellent in uniformity and transparency of the coating. As a result, the sticking portion and the non-sticking portion of the in-mold label 1 in the resin molded product appear to be integrated with little or no difference in appearance.

Examples of a method for obtaining an aqueous resin emulsion in which an olefin-based resin is dispersed in water include, for example, Japanese Patent Application Laid-Open Nos. 58-118843, 56-2149, 56-106940, and 56. -157445 and the like. If it says concretely about the said method, first, copolymer resin will be supplied to a twin-screw extruder, and it will melt-knead. Thereafter, water containing the dispersion liquid is introduced into the twin screw extruder from a liquid introduction tube provided in the compression section or vent region of the twin screw extruder, and the copolymer resin and water melted by the rotating screw. Knead. And the obtained kneaded material is reverse-phased in the housing of the twin screw extruder and discharged to the atmospheric pressure region from the outlet nozzle of the extruder. Thereafter, water is further added as necessary, and the resultant is stored in a storage tank to obtain an aqueous resin emulsion.

The average particle diameter of the olefin resin particles in the olefin resin emulsion is preferably 0.01 to 3 μm, and more preferably 0.1 to 1 μm. When the average particle diameter of the olefin-based resin particles is within the above range, the phase is stable in the state of the dispersion, and the storage property and coating property of the liquid are excellent. Further, the seal layer 3 formed by applying the dispersion liquid tends to be more excellent in transparency after being bonded to the resin molded body, that is, in the state of a resin molded product.

Here, the “average particle diameter” in this specification is calculated by the following procedure. First, a sample solution (for example, an olefin resin emulsion solution) is dried under low temperature and reduced pressure conditions. The dried sample is enlarged to an appropriate magnification (for example, 1,000 times) using a scanning electron microscope, and a photographic image is taken. From the photographed image, the average value of the major axis of 100 randomly selected particles present in the sample is calculated. Thereby, an average particle diameter is calculated.

The solid content concentration of the olefin resin emulsion is preferably 8 to 60% by mass, more preferably 20 to 50% by mass. When the solid content concentration is within the above range, the phase is stable in the state of the dispersion, and a dispersion having excellent liquid storage and coating properties can be obtained.

Examples of commercially available products of such olefin resin emulsions include Life Bond HC-12, HC-17, and HC-38 (trade names) manufactured by NEIEI KAKO Co., Ltd., AD-37P295J manufactured by Toyo Morton Co., Ltd. And EA-H700 (trade name), Aquatex EC-1200, EC-1700, EC-1800, EC-3500, and AC-3100 (trade name) manufactured by Chuo Rika Kogyo Co., Ltd. Examples of commercially available coating liquids in which the olefinic resin is dissolved in an organic solvent include THS-4884 and AD-1790-15 (trade name) manufactured by Toyo Morton Co., Ltd.

(Coating liquid application)
A method for coating the coating solution containing the olefin resin on the base material layer 2 is not particularly limited, but includes a gravure coater, a micro gravure coater, a reverse coater, a blade coater, a Mayer bar coater, and an air knife coater. A method using a coating apparatus such as

In addition, said coating method is applicable also when applying a coating liquid on the intermediate | middle layer mentioned later.

After coating the coating liquid, the solvent (main component is water, for example) is removed by drying, and the resulting coating is used as the seal layer 3. The thickness of the sealing layer 3 is preferably 0.3 to 10 μm. When the thickness of the seal layer 3 is 0.3 μm or more, the resin molded body and the in-mold label 1 are firmly fused, so that the adhesive strength is further improved. On the other hand, when the thickness of the seal layer 3 is 10 μm or less, drying after coating becomes easy, and deterioration of the adhesive strength due to deterioration of transparency and insufficient cohesive force can be effectively prevented. The thickness of the seal layer 3 is more preferably 1 to 5 μm. In this case, the above effect is further improved.

The coating amount of the coating liquid is appropriately adjusted so that the thickness of the seal layer 3 is in an appropriate range. The solid concentration of the coating liquid is preferably 10 to 60% by mass. When the solid content concentration of the coating liquid is within the above range, the thickness of the seal layer 3 is substantially uniform. As a result, excellent adhesiveness is obtained over the entire surface of the seal layer 3, and the adhesiveness of the in-mold label 1 as a whole is further improved.

Further, the lower limit of the adhesive strength of the in-mold label 1 mainly due to the adhesive strength of the seal layer 3 is preferably 100 gf / 15 mm or more. If the adhesive strength is 100 gf / 15 mm or more, the in-mold label 1 is sufficiently adhered to the resin molded body and hardly peeled off, so that there is almost no problem in practical use. Furthermore, in order to more surely avoid the occurrence of practical problems, the lower limit of the adhesive strength of the in-mold label 1 is more preferably 200 gf / 15 mm or more, further preferably 300 gf / 15 mm or more, 400 gf / 15 mm or more is particularly preferable. On the other hand, the upper limit of the adhesive strength is not particularly limited, but is preferably 1,000 gf / 15 mm or less.

For example, the adhesive strength of the in-mold label 1 can be adjusted to the above range by selecting the constituent components of the seal layer 3 from the preferable materials described above and setting the temperature in the molding machine within a specific range. . The temperature inside the molding machine during molding of the resin molded product is preferably 0 to 50 ° C, and more preferably 10 to 40 ° C.

In one embodiment, the adhesive strength of the seal layer 3 is such that when the in-mold label 1 attached to the resin molded product is peeled off from the resin molded body, the seal layer 3 is on the side of the in-mold label 1 (ie, the base It adjusts so that it may remain in the material layer 2 or the intermediate | middle layer side mentioned later). In another embodiment, the adhesive strength of the seal layer 3 is such that the seal layer 3 remains on the resin molded product side when the in-mold label 1 attached to the resin molded product is peeled off from the resin molded product. Adjusted.

For example, when the adhesive strength between the base material layer 2 or the intermediate layer and the seal layer 3 is smaller than the adhesive strength between the constituent resin of the resin molded body and the seal layer 3, the in-mold label 1 is removed from the resin molded body. When peeled off, the seal layer 3 remains on the resin molded body side. In this case, a trace of the label remains on the portion of the resin molded body where the in-mold label 1 is attached. Thereby, it can prevent that a third party peels off the in-mold label 1 and impersonates a product.

On the other hand, when the adhesive strength between the base material layer 2 or the intermediate layer and the seal layer 3 is larger than the adhesive strength between the constituent resin of the resin molded body and the seal layer 3, the in-mold label 1 is removed from the resin molded body. When peeled off, the seal layer 3 remains on the in-mold label 1 side. In this case, the mark of a label is not seen in the part to which the in-mold label 1 was stuck among the resin moldings. This makes it extremely easy to recycle the resin molded body.

In addition, the measuring method and conditions of the adhesive strength of the in-mold label 1 in this specification employ | adopt the method and conditions used in the below-mentioned Example in order to define the said physical property uniquely. However, the description in the examples does not limit the method and conditions for measuring the adhesive strength in the in-mold label 1 of the present embodiment.

<1-4. Applications of in-mold labels>
Although the in-mold label 1 of this embodiment can be used regardless of the method of in-mold molding, when manufacturing a resin molded product in which the in-mold label 1 is bonded to a resin molded body by stretch blow molding. Are particularly preferably used.

In-mold molding is performed, for example, according to the following procedure. First, the in-mold label 1 is installed in the molding machine so that the side of the base material layer 2 is in contact with the inner wall of the molding machine. At this time, the seal layer 3 is located on the opposite side of the surface facing the inner wall of the molding machine of the in-mold label 1. Next, a preform mainly composed of a thermoplastic resin is introduced into the molding machine.

As a method of molding a resin molded product in a molding machine, blow molding (sometimes referred to as hollow molding) can be exemplified. Blow molding includes direct blow molding using a resin parison and stretch blow molding using a resin preform.

Direct blow molding is a technique in which a raw resin is heated to a temperature equal to or higher than the melting point of the resin, a parison is formed with the raw resin melted, and the parison is expanded with compressed air. On the other hand, stretch blow molding is a technique in which a preform is heated to the softening point of the raw material resin, the preform is stretched with a rod in a deformable state, and then expanded by compressed air.

Direct blow molding and stretch blow molding differ even when the same resin is used as a raw material, but the state of the raw material resin at the time of molding is different (that is, it is in a molten state in direct blow molding and in a softened state in stretch blow molding. Therefore, the amount of heat applied to the raw resin is also greatly different.
When a resin molded product is produced by direct blow molding, the low melting point resin is sufficiently melt activated by the amount of heat given to the label by the molten parison. Therefore, a resin molded product having no problem in quality such as adhesive strength can be obtained.
On the other hand, when a resin molded product is manufactured by stretch blow molding, the preform cannot give a sufficient amount of heat to the label to melt activate the low melting point resin of the label. Therefore, the subject that a label cannot be adhere | attached or a label peels easily may arise.

For the purpose of solving the above-mentioned problems, when a label is attached to a resin molded body by stretch blow molding, as a material for the adhesive layer (for example, the seal layer 3) of the label, It is conceivable to use a low delayed adhesive. However, delayed adhesives are not visually transparent at room temperature. For this reason, it has been considered that it is not suitable as an adhesive layer for a label to be attached to a resin molded product formed from a visually transparent resin such as PET or polycarbonate (sometimes referred to as PC).

The present inventors have repeatedly investigated physical properties such as the heat of fusion, the average refractive index, and the crystallinity of the sealing layer included in the in-mold label. As a result, a resin molded product in a state in which an in-mold label having an average refractive index equivalent to that of the resin molded product is attached to a resin molded product having excellent transparency such as a PET bottle obtained by stretch blow molding and the molded product The in-mold label suitable for the product has been developed.
The resin molded product is a stretch blow molded product that is extremely excellent in transparency, and the contents can be visually recognized from either the pasted portion or the non-sticked portion of the in-mold label. Furthermore, the resin molded product is a resin molded product with an in-mold label, in which the in-mold label and the resin molded product appear to be integrated, that is, a non-label look as a resin molded product.

<1-5. Stretching of base material layer>
The base material layer 2 constituting the in-mold label 1 may be a non-stretched film (sometimes referred to as unstretched) or a stretched film stretched at least in a uniaxial direction. The in-mold label 1 including an unstretched film as the base material layer 2 is more excellent in transparency and shape followability to a stretch blow molded product. On the other hand, the in-mold label 1 including the stretched film as the base material layer 2 is more excellent in transparency, lightness, and thickness uniformity due to thinning.

When the base material layer 2 is stretched, any of various known methods or a combination thereof can be used. As a method of stretching the base material layer 2, longitudinal stretching using the difference in peripheral speed of the roll group, transverse stretching using a tenter oven, sequential biaxial stretching combining longitudinal stretching and transverse stretching, tenter oven and linear motor Examples thereof include simultaneous biaxial stretching by a combination, simultaneous biaxial stretching by a combination of a tenter oven and a pantograph, rolling, and the like. When the base material layer 2 is stretched by the inflation molding method, it is preferable to adjust the blown air amount and stretch the base material layer 2 by simultaneous biaxial stretching.

The draw ratio is not particularly limited, but may be appropriately determined in consideration of the properties of the thermoplastic resin mainly used for the base material layer 2 that is the support of the in-mold label 1 and the physical properties of the resulting resin film. . For example, as the thermoplastic resin of the base material layer 2, at least one of a homopolymer of propylene and a copolymer thereof is used, and the stretching ratio when the thermoplastic resin is uniaxially stretched is 1.2 to 12 times. Preferably, it is 2 to 10 times. When the above-mentioned thermoplastic resin is biaxially stretched, the stretch ratio is preferably 1.5 to 60 times, more preferably 4 to 50 times as the area ratio.

On the other hand, when a thermoplastic resin other than the homopolymer of propylene and its copolymer is used as the thermoplastic resin of the base material layer 2 and the thermoplastic resin is uniaxially stretched, the draw ratio is 1.2 to 10 Is preferably doubled, and more preferably 2 to 5 times. When the above-mentioned thermoplastic resin is biaxially stretched, the area magnification is preferably 1.5 to 20 times, more preferably 4 to 12 times as the area magnification.

The stretching temperature may be appropriately determined within a temperature range that is not lower than the glass transition temperature of the thermoplastic resin mainly contained in the base material layer 2 and not higher than the melting point of the crystalline phase of the thermoplastic resin. When the thermoplastic resin is a homopolymer of propylene (melting point: 155 to 167 ° C.), the stretching temperature is preferably 100 to 166 ° C., more preferably 1 to 70 ° C. lower than the melting point. . The stretching speed is not particularly limited, but is, for example, 20 to 350 m / min.

The base material layer 2 is more preferably an unstretched film of polypropylene resin (sometimes referred to as a CPP film) or a stretched film (for example, an OPP film). The base material layer 2 is more preferably an unstretched film of polypropylene resin. When the base material layer 2 is an unstretched film of a polypropylene resin, crystallization due to the stretching orientation of the polypropylene resin molecules is suppressed. Thereby, the base material layer 2 has the outstanding softness | flexibility which can also follow the shape change in the case of manufacturing a resin molded product by stretch blow molding, maintaining the outstanding transparency.

In addition, the matter described about extending | stretching of the base material layer 2 can be applied similarly also to the intermediate | middle layer and printable layer mentioned later.

<1-6. Intermediate layer>
FIG. 2 is a cross-sectional view of an in-mold label according to another embodiment of the present invention. The in-mold label 10 includes a base material layer 11, a seal layer 12, and an intermediate layer 13 between the base material layer 11 and the seal layer 12. In the embodiment shown in FIG. 2, the in-mold label 10 is a resin film having a laminated structure including a base material layer 11, an intermediate layer 13, and a seal layer 12.
Each of the base material layer 11 and the seal layer 12 may have the same configuration as the base material layer 2 and the seal layer 3 in the in-mold label 1. Description of the details of the base material layer 11 and the sealing layer 12 is omitted.

The intermediate layer 13 contains an olefin resin. It is estimated that the intermediate layer 13 mediates the base material layer 11 and the seal layer 12 and increases the adhesive force between the base material layer 11 and the seal layer 12. Further, by providing the intermediate layer 13, even when heating at a relatively low temperature (for example, 90 to 110 ° C., preferably 95 to 110 ° C.) as in stretch blow molding, the adhesion of the seal layer 12 during heat sealing is performed. The strength can be further increased.

More specifically, the melting point of the olefin resin constituting the intermediate layer 13 is 5 ° C. lower than the melting point of the thermoplastic resin constituting the base layer 11 and the melting point of the olefin resin constituting the seal layer 12. It is preferably higher by 5 ° C or more. In this case, since a melting point gradient occurs between the layers, the adhesion between the base material layer 11 and the seal layer 12 is further improved.

As such an olefin resin, a polyethylene resin having a melting point of 110 ° C. or lower is preferable. Specific examples of the polyethylene resin having a melting point of 110 ° C. or less include high-density polyethylene having a density of more than 0.94 g / cm ³ and not more than 0.97 g / cm ³ , and a density of 0.90 to 0.94 g / cm ³ . Low- or medium-density high-pressure polyethylene, linear low-density polyethylene with a density of 0.86 to 0.94 g / cm ³ , ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer Polymer, ethylene / acrylic acid alkyl ester copolymer (the alkyl group preferably has 1 to 8 carbon atoms), ethylene / methacrylic acid alkyl ester copolymer (the alkyl group preferably has 1 to 8 carbon atoms) , Metal salts of ethylene / methacrylic acid copolymers (such as metals such as Zn, Al, Li, K, and Na), ethylene / maleic anhydride copolymers, etc. Can be mentioned.

Among these, the olefin resin has a crystallinity (X-ray diffractometry) of 10 to 60% and a number average molecular weight of 10,000 to 40,000, and is at least one of high pressure polyethylene and linear polyethylene. It is preferable to contain. Particularly, the olefin resin is a linear linear polyethylene obtained by copolymerizing 40 to 98 parts by mass of ethylene and 2 to 60 parts by mass of an α-olefin having 3 to 30 carbon atoms in the presence of a metallocene catalyst. It is more preferable.
In this case, the adhesiveness under relatively low temperature conditions of, for example, 90 to 110 ° C. (preferably 95 to 110 ° C.) is further improved. The metallocene catalyst may be a metallocene / alumoxane catalyst, such as a metallocene compound and a compound that reacts with the metallocene compound to form a stable anion as disclosed in, for example, WO 92/01723. The catalyst which consists of may be sufficient.

The above olefin resins may be used alone or in a mixture of two or more. Among these, since the transparency is further improved, it is preferable to use the above olefinic resin alone.

The intermediate layer 13 in the present embodiment may optionally contain other known additives for resin as long as the target transparency and adhesiveness are not impaired. Examples of the resin additive include an antistatic agent, a plasticizer, an antioxidant, and an ultraviolet absorber.

The thickness of the intermediate layer 13 is preferably 1 to 30 μm. When the thickness is 1 μm or more, the intermediate layer is melted together with the seal layer by the heat of the preform when the molded product is molded, and the molded product and the label are easily bonded firmly. On the other hand, when the thickness is 30 μm or less, the occurrence of curling of the label can be suppressed. Moreover, offset printing on the label is easy, and the label can be easily fixed to the molding machine. The thickness of the intermediate layer 13 is more preferably 5 to 20 μm. In this case, the above effect is further improved.

<1-7. Printable layer>
FIG. 3 is a cross-sectional view of an in-mold label according to another embodiment of the present invention. The in-mold label 20 includes a base material layer 21, a seal layer 22, an intermediate layer 23 between the base material layer 21 and the seal layer 22, and a surface on the seal layer 22 side among the surfaces of the base material layer 21. And a printable layer 24 on the opposite side. In the embodiment shown in FIG. 3, the in-mold label 20 is a resin film having a laminated structure including a printable layer 24, a base material layer 21, an intermediate layer 23, and a seal layer 22.

Each of the base material layer 21, the seal layer 22, and the intermediate layer 23 may have the same configuration as the base material layer 2, the seal layer 3, and the intermediate layer 13 in the in-mold label 1 or the in-mold label 10. Description of the details of the base material layer 21, the sealing layer 22, and the intermediate layer 23 is omitted. In other embodiments, the in-mold label 20 may not have the intermediate layer 23.

The printable layer 24 may be the outermost layer on the substrate layer 21 side of the in-mold label 20. An image is printed on the printable layer 24 according to the use of the in-mold label 20. The image may include characters or characters. Note that an image may not be printed on the printable layer 24. Printing on the printable layer 24 may be performed at any stage of manufacturing the in-mold label 20. Printing on the printable layer 24 may be performed before and after the manufacture of the in-mold label 20.

In-mold molding using the in-mold label 20 is performed, for example, according to the following procedure. First, the in-mold label 20 is installed in the molding machine so that the printable layer 24 side contacts the inner wall of the molding machine. At this time, the seal layer 22 is located on the opposite side of the surface of the in-mold label 20 that faces the inner wall of the molding machine. Next, a preform mainly composed of a thermoplastic resin is introduced into the molding machine.

Materials for the printable layer 24 include polypropylene resin, high density polyethylene, medium density polyethylene, linear linear low density polyethylene, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / alkyl acrylate ester Copolymer (alkyl group preferably has 1 to 8 carbon atoms), ethylene / methacrylic acid alkyl ester copolymer (alkyl group preferably has 1 to 8 carbon atoms), ethylene / methacrylic acid copolymer. Polyolefin resins such as metal salts (eg, metals such as Zn, Al, Li, K, and Na), poly-4-methyl-1-pentene, and ethylene-cycloolefin copolymers; polyethylene terephthalate resin, polybutylene succinate Resin, polyester resin such as polylactic acid; polyvinyl chloride resin; nylon ABS resins; 6, nylon-6,6, nylon-6,10, polyamide-based resins such as nylon-6,12 and ionomer resin may be exemplified. The material of the printable layer 24 is more preferably a thermoplastic resin having a melting point in the range of 130 to 280 ° C. such as polypropylene resin, high-density polyethylene, and polyethylene terephthalate resin. These resins may be used alone or as a mixture of two or more.

Among these, it is preferable to use polyolefin resin. Among the polyolefin resins, it is more preferable to use at least one of a polypropylene resin and a high density polyethylene. Thereby, the printable layer 24 which can suppress cost and is excellent in water resistance and chemical resistance is obtained.
As the polypropylene-based resin, it is preferable to use isotactic or syndiotactic and propylene homopolymers having various degrees of stereoregularity, propylene and α-olefin copolymers as main components.
Examples of the α-olefin include ethylene, 1-butene, 1-hexene, 1-heptene, 4-methyl-1-pentene and the like.

The above copolymer may be any of a binary system, a ternary system, and a quaternary system. In addition, the copolymer may be a random copolymer or a block copolymer.

The printable layer 24 preferably contains a thermoplastic resin having a polar group. As a result, the printable layer 24 having further excellent ink adhesion can be obtained. Examples of the thermoplastic resin having a polar group include an ethylene / vinyl acetate copolymer, an ethylene / acrylic acid copolymer, and an ethylene / acrylic acid alkyl ester copolymer (the alkyl group preferably has 1 to 8 carbon atoms). Ionomer, ethylene / methacrylic acid alkyl ester copolymer (the alkyl group preferably has 1 to 8 carbon atoms), ethylene / methacrylic acid copolymer metal salt (eg, Zn, Al, Li, K, and Na as metals) Etc.), maleic acid-modified polypropylene, maleic acid-modified polyethylene, maleic acid-modified ethylene / vinyl acetate copolymer, and the like.

Among these, a maleic acid-modified ethylene / vinyl acetate copolymer is preferable. Thereby, the printable layer 24 further excellent in ink adhesion can be obtained.
The printable layer 24 may further include an inorganic powder, an antioxidant, an ultraviolet stabilizer, and the like as necessary. Examples of the inorganic powder include calcium carbonate, aluminum hydroxide, and talc.

The thickness of the printable layer 24 is preferably in the range of 1 to 30 μm. If the thickness is 1 μm or more, ink adhesion is improved. On the other hand, if the thickness is 30 μm or less, the occurrence of curling of the in-mold label 20 can be suppressed. Further, offset printing on the in-mold label 20 is easy, and the in-mold label 20 can be easily fixed to the molding machine. The thickness of the printable layer 24 is more preferably 5 to 20 μm. In this case, the above effect is further improved.

The in-mold label 20 of the present embodiment may be subjected to an activation process as necessary. The printability of the surface of the printable layer 24 is improved by the activation treatment. Examples of the activation treatment include one or more oxidation treatment methods selected from the group consisting of corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, and ozone treatment. In particular, corona treatment or frame treatment is preferably performed.

In the case of corona treatment, the degree of activation treatment is, for example, 600 to 12,000 J / m ² (10 to 200 W · min / m ² ), preferably 1200 to 9,000 J / m ² (20 to 150 W · min). / M ² ). If it is 600 J / m ² (10 W · min / m ² ) or more, the effect of the corona discharge treatment can be sufficiently obtained, and the adhesion of the ink becomes better. In addition, in the range exceeding 12,000 J / m ² (200 W · min / m ² ), since the effect of the treatment is almost the same, 12,000 J / m ² (200 W · min / m ² ) or less is sufficient. It is.

On the other hand, in the case of frame processing, it is, for example, 8,000 to 200,000 J / m ² , and preferably 20,000 to 100,000 J / m ² . If it is 8,000 J / m ² or more, the effect of the frame treatment can be sufficiently obtained, and the adhesion of the ink becomes better. Further, in the range exceeding 200,000 J / m ² , the effect of the treatment is almost the same, and therefore 200,000 J / m ² or less is sufficient.

Examples of the printing method on the printable layer 24 include letter printing, gravure printing, offset printing, flexographic printing, and screen printing. On the in-mold label 20, for example, a barcode, a manufacturer, a sales company name, a character, a product name, and a usage method are printed. The printed in-mold label 20 may be separated into labels having a required shape and size by punching. The in-mold label 20 may be used as a label that is partially attached to a part of the surface of the resin molded body. The in-mold label 20 may be used as a blank that surrounds the side surface of the container-shaped molded body over one circumference. The in-mold label 20 may be used as a label attached to at least one of the front side and the back side of the container-like molded body.

<1-8. Layer structure of in-mold label>
As described so far, the in-mold label of each embodiment includes the base layer / sealing layer, base layer / intermediate layer / sealing layer, printable layer / base layer / sealing layer, and printable layer / Any one of the base layer / intermediate layer / sealing layer can be employed.

In one embodiment, the base material layer and at least one of the intermediate layer and the printable layer are prepared in advance as a laminated resin film. Then, the sealing layer is provided by the coating method etc. on the surface of the base material layer or intermediate | middle layer of a laminated resin film, and the in-mold label of each embodiment is obtained.

Examples of the method for producing a laminated resin film include various known film production techniques and combinations thereof. More specifically, a co-extrusion method using a multi-layer T-die connected to a screw type extruder, an extrusion lamination method using a plurality of dies, a melt laminating method, a heat laminating method, and various adhesives are used. Examples of the dry laminate method and the wet laminate method may be given. A combination of multilayer die and extrusion lamination may be used. The coextrusion method is preferably used because each layer can be bonded more firmly.

<1-9. Effect of in-mold label>
When developing the in-mold label of each embodiment, the present inventors used a transparent resin film such as a multi-component copolymer resin film and an unstretched polypropylene film disclosed in Patent Document 3 as a label base material. The in-mold label containing the said base material and the contact bonding layer which consists of a material with low heat of fusion like the delayed adhesive disclosed by patent document 4 was produced. However, the in-mold label adhered to the resin molded body appeared to be cloudy because the sealing layer was inferior in transparency compared to the resin molded body. Also, the in-mold label appeared to float up. Thus, it is difficult to achieve excellent transparency by the in-mold label composed of the multi-component copolymer resin film disclosed in Patent Document 3 and the delayed adhesive disclosed in Patent Document 4. I found out.

Therefore, the present inventors made extensive studies with the following three points as technical issues in providing in-mold labels. The first point is an in-mold that is particularly excellent for stretch blow molding that requires adhesion under relatively low temperature molding conditions (for example, the temperature of the preform before molding is 90 to 110 ° C., preferably 95 to 110 ° C.). Provide a label. The second point is to provide an in-mold label having sufficient adhesive strength with the resin molded body. The third point is to provide an in-mold label that is excellent in transparency and looks like the resin molded product is integrated without causing a difference in appearance between the label and the resin molded body.

As a result, as described in the above embodiments, at least a base material layer and a sealing layer laminated on the surface of the base material layer are provided, and the base material layer conforms to JIS-K-7136. The internal haze measured is 0.1 to 20%, the seal layer contains an olefin resin, and includes the heat of fusion, the recrystallization temperature, and the average refractive index and crystallinity under specific conditions. An in-mold label has been conceived, at least one of which is within a specific numerical range.

According to each of the above embodiments, the adhesive strength with the resin molding is sufficient even under relatively low temperature (for example, 90 to 110 ° C., preferably 95 to 110 ° C.) bonding conditions, and the label is excellent in transparency. It is possible to provide an in-mold label in which the resin molded product looks integrated without causing a difference in appearance from the resin molded body.

[2. Resin molded product]
One embodiment of the present invention relates to a resin molded product. The resin molded product includes a resin molded body and the in-mold label of each of the above embodiments that is adhered to the resin molded body.

The in-mold label of each of the embodiments described above is an in-mold for hollow molding (for stretch blow molding), in which a heated resin preform is crimped to the inner wall of a molding machine (for example, a mold) with a rod and compressed air. It can be suitably used as a mold label. The stretch blow-molded article manufactured using the in-mold label of each embodiment has a small difference in appearance between the attached part and the non-attached part of the in-mold label, and gives a higher degree of unity. Therefore, it can be said that the resin molded product of this embodiment is a resin molded product by stretch blow molding to which an in-mold label is attached.

Among the stretch blow molded products, the resin molded body preferably contains at least one resin selected from the group consisting of polyester resins, polycarbonate resins, polystyrene resins, polypropylene resins, and polyethylene resins. When the resin molded body contains the above-described resin, the transparency is further improved with the in-mold label attached to the resin molded product of the present embodiment. Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polybutylene succinate, polylactic acid, and the like. Examples of the polystyrene resin include polystyrene, styrene acrylonitrile copolymer, styrene butadiene copolymer and the like.

The resin used for the resin molding may be a transparent or natural color that does not include pigments and dyes, or may be an opaque or colored one that includes pigments or dyes. Even if the resin constituting the resin molded body is colored, the difference between the hue of the resin molded body itself and the hue of the resin molded body via the in-mold label is small, and the sense of unity between the resin molded body and the in-mold label is small. Will be excellent. When the resin constituting the resin molded body is transparent, both the resin molded body and the in-mold label are transparent, and the resin molded product as a whole has a sense of unity and the contents can be easily seen from any part of the resin molded product. .

It is preferable that the difference in haze between the pasted part and the non-sticked part of the in-mold label in the resin molded product is 20% or less. When the haze difference is 20% or less, the sense of unity between the in-mold label and the resin molded body is further improved, and a resin molded product by stretch blow molding with a non-label look in-mold label attached thereto is obtained. Furthermore, since the above effect is further improved, the haze difference is more preferably 15% or less.

In the present specification, the difference in haze between the in-mold label adhering part and the non-adhering part is calculated according to the method and conditions used in the examples described later for the purpose of uniquely defining the physical property values. Adopted values. However, this does not limit the measuring method and conditions of the haze difference in the present embodiment.

The color difference between the in-mold label sticking part and the non-sticking part, that is, the color difference between the in-mold label and the resin molding in the resin molded product is preferably 3.2 or less. If the color difference is 3.2 or less, the color difference is hardly felt with the naked eye, and the sense of unity between the in-mold label and the resin molded body in the resin molded product can be further enhanced. Furthermore, since the above effect is further improved, the color difference is more preferably 1.6 or less, and further preferably 1.2 or less.
In addition, the value measured by the method performed in the below-mentioned Example is employ | adopted for the measurement method and conditions of a color difference in this specification in order to unambiguously define the said physical-property value. However, this does not limit the color difference measurement method and conditions in this embodiment.

[3. Method for producing resin molded product]
In one embodiment, when the resin molded body is molded by a molding machine, the resin molded article includes a step in which an in-mold label placed inside the molding machine is attached to the resin molded body. A method of manufacturing is provided. The molding machine is not particularly limited, and is, for example, a molding die.

FIG. 4 is a perspective view showing a resin molded product 30 according to an embodiment. In the embodiment of FIG. 4, the resin molded product 30 is a labeled container in which an in-mold label 32 is attached to a resin molded body 31 (sometimes referred to as a container or a bottle). For example, when manufacturing the resin molded product 30 using the rectangular in-mold label 32, the circumferential direction of the trunk | drum 33 of the resin molded body 31 and the longitudinal direction of the in-mold label 32 match the in-mold label 32. And placed on the inner wall of the molding machine.

When using a material that becomes white turbid when recrystallized as the seal layer included in the in-mold label or the olefin resin included in the seal layer, the recrystallization temperature of the seal layer or the olefin resin is a resin. The temperature is preferably higher than the temperature at which the molded body is molded by a molding machine. In this case, since the constituent components of the seal layer are not heated at a molding temperature higher than the recrystallization temperature through in-mold molding, the loss of transparency due to recrystallization, that is, the occurrence of white turbidity is prevented. Can do.

As described above, according to the resin molded product of the above embodiment and the manufacturing method thereof, when the in-mold label described above is integrally molded in the molding resin and the molding machine, the label has excellent adhesiveness ( The adhesive strength between the label and the resin molded body is high), and the transparency of the sticking part of the label is excellent (the label and the resin molded body appear to be integrated). A bonded resin molded product is obtained. Furthermore, the resin molded product to which the in-mold label of the above embodiment is attached is particularly suitable for a molded product by stretch blow molding.

Hereinafter, the present invention will be described more specifically with reference to production examples, examples and test examples. The materials, usage fees, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the technical scope of the present invention is not limited by the specific examples shown below.

Here, the measurement methods and evaluation methods of physical properties in Production Examples, Examples, and Comparative Examples (sometimes referred to as “Examples”) were carried out by the following methods.

(1) Internal haze Measured according to JIS-K-7136: 2000 using a haze meter (trade name: NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.).

Liquid paraffin (manufactured by Wako Pure Chemical Industries, Ltd., for infrared analysis) was applied to the front and back surfaces of the measurement location of the base material layer sample obtained in each production example. Then, it was sandwiched between two slide glasses (manufactured by Matsunami Glass Industry Co., Ltd., trade name: S-7213, preclin water rim polish, thickness 0.9 to 1.2 mm) so that there was no air gap. In this way, a sample for measurement was prepared.

For the production example in which at least one of the intermediate layer and the printable layer was further provided on the front and back surfaces of the base material layer, the obtained laminate was handled as a sample for measuring internal haze.

(2) Adhesive strength of in-mold label The in-mold label obtained in each of the following Examples and Comparative Examples was punched into a rectangle having a long side of 8 cm and a short side of 6 cm. Thus, an in-mold label used for a resin molded product by stretch blow molding to which the in-mold label was attached (sometimes referred to as “molded product with label”) was prepared.

The above-mentioned in-mold label is placed inside the molding die of a stretch blow molding machine (manufactured by Nissei ASB, trade name: ASB-70DPH) so that the opposite surface of the seal layer is in contact with the die (that is, The in-mold label was placed so that the sealing layer faced the preform side. The in-mold label was installed so that the long side of the in-mold label was adhered in parallel to the circumferential direction of the body of the resin molded body. The mold was cooled so that the surface temperature was in the range of 20 to 45 ° C.

Next, the polyethylene terephthalate preform was preheated to 95 ° C. Then, the preform was stretch blow molded in a mold at a mold temperature of 45 ° C. for 1 second under a blow pressure of 2.5 MPa. Then, it cooled to 50 degreeC in 15 seconds. In this way, a molded article with a label was obtained. Among the obtained molded articles with labels, the resin molded body was a container having a square body having a height of 12 cm and a side of about 7 cm.

Next, each of the obtained molded articles with labels was stored for 2 days in an environment of a temperature of 23 ° C. and a relative humidity of 50%. Then, the sticking part of the label was cut out by a cutter, and the length of the circumferential direction of the body of the container was 12 cm (the sticking part of the label was 9 cm, the non-sticking part was 3 cm) and the width was 1.5 cm. A total of six measurement samples were collected from two containers. The measurement sample was collected so that the label was attached over the entire width of the measurement sample.

Next, the label was carefully peeled off from the non-sticking part of the label, and peeled about 1 cm. At this time, a PET film (thickness: 50 μm) having the same width was adhered to the label with an adhesive to form a gripping portion on the label side, and a sample for measuring adhesive strength was prepared.

Next, based on JIS-K-6854-2: 1999, peeling was performed 180 degrees using a tensile tester (manufactured by Shimadzu Corporation), and the adhesive strength was measured. As specific conditions for calculating the adhesive strength, the average value of the peeling force between the peeling lengths of 25 mm to 75 mm was measured, and the value obtained by averaging the measured values of the six samples was determined as the adhesive strength. did.

In addition, as for the molded product with a label of Comparative Example 2, the most part of the label was lifted from the container, and the adhesion was poor enough to be peeled off during sampling. Therefore, in Comparative Example 2, the adhesive strength could not be measured.

(3) Color difference ΔE ^* _ab
The sticking part and the non-sticking part (that is, the container part) of the label in the molded article with the label obtained in the above “(2) In-mold label adhesive strength” were each cut with a cutter. About each sample of the sticking part and non-sticking part which were cut off, based on JIS-Z-8730: 2009, the color was measured using the spectral densitometer (X-Rite company make, brand name: X-Rite508). . Based on the color difference (ΔL ^* , Δa ^* , Δb ^* ) between the measured L ^* a ^* b ^* display colors, the lightness index L ^* and chromaticness index a ^* , b ^* of the surface color were measured. The color difference ΔE ^* _ab was determined using Equation (1).

ΔE ^* _ab = [(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² ] ^1/2 (1)

The above measurement method is particularly useful when an opaque resin (sometimes referred to as a colored resin) is used for molding a resin molded product.

In this example, the color difference was visually observed according to the following evaluation criteria.
○: Good (the color difference is hardly felt with the naked eye)
×: Impossible (color difference is felt with the naked eye)

(4) Difference in haze between the sticking part and non-sticking part of the label Molding with a label in accordance with JIS-K-7136: 2000 using a haze meter (trade name: NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) The haze of the sticking part and the non-sticking part of the label in the product was measured. Of the molded products with labels obtained in each of the examples and comparative examples, a sticking part and a non-sticking part of the label were cut out to prepare samples for measurement.

In addition, since it is the same as that of "(1) Internal haze" about the above-mentioned base material layer about the measuring method and conditions of haze, explanation here is omitted.

(5) Crystallinity, melting point, density, and thickness The crystallinity of the resin used in this example was calculated using an X-ray diffractometer. The melting point of the resin used in this example was the maximum peak temperature (Tm) of the endothermic curve measured using a differential scanning calorimeter. The density of the olefin resin used in this example was measured according to JIS-K-7112.

The thickness of the entire in-mold label of this example was measured using a constant pressure thickness measuring instrument (trade name: PG-01J, manufactured by Teclock Co., Ltd.) according to JIS-K-7130. The thickness of each layer was measured by the following procedure. First, the sample to be measured was cooled to a temperature of −60 ° C. or lower with liquid nitrogen. A razor blade (manufactured by Chic Japan Co., Ltd., trade name: Proline Blade) was applied to the sample after cooling placed on a glass plate at a right angle and cut to prepare a sample for cross-sectional observation. A cross section of the sample was observed with a scanning electron microscope (trade name: JSM-6490, manufactured by JEOL Ltd.), and the boundary line for each layer (coating film and resin composition) was determined depending on the difference in appearance due to the difference in composition. Was determined. Thus, the thickness of each layer was calculated | required by multiplying the ratio of the thickness of the whole in-mold label, and the thickness of each observed layer.

(Production Example 1)
As a resin composition for the substrate layer, 100% by mass of a propylene homopolymer (trade name: Novatec PP MA3U, manufactured by Nippon Polypro Co., Ltd.) was melt-kneaded at 240 ° C. using an extruder. Further, as the resin composition for the intermediate layer, ethylene / hexene-1 copolymer (manufactured by Nippon Polyethylene Co., Ltd., trade name: Kernel KS340T) 85.7% by mass, low density high pressure polyethylene (manufactured by Nippon Polyethylene Co., Ltd., product) Name: Novatec LD LC720) 9.5% by mass and antistatic agent (manufactured by Nippon Polyethylene Co., Ltd., trade name: Novatec LL LX-AS) 4.8% by mass was melt kneaded at 240 ° C. using an extruder. did. In addition, as a resin composition for the printable layer, 70% by mass of a propylene homopolymer (trade name: Novatec PP MA3U, manufactured by Nippon Polypro Co., Ltd.) and a low-density high-pressure polyethylene (trade name: Novatec, manufactured by Nippon Polyethylene Co., Ltd.) LD LC720) 30% by mass of the mixture was melt-kneaded at 240 ° C. using an extruder. In addition, these melt kneading | mixing was performed using the mutually different extruder.

These kneaded materials were supplied to one co-extrusion T-die and laminated in three layers in the T-die. Next, the sheet was extruded from a T-die in the form of a sheet, which was guided between a mirror-finished cooling roll and a mat-like rubber roll, and cooled while being pinched under a linear pressure of about 1.5 kg / cm. In this way, an unstretched laminated resin film having a three-layer structure of printable layer / base material layer / intermediate layer was obtained.

Next, the obtained laminated resin film was guided to a corona discharge treatment device with a guide roll, the surface on the printable layer side was subjected to corona discharge treatment at a treatment amount of 50 W · min / m ² , and the ear portion was cut off. Then, it wound up with the winder.

As the above-mentioned cooling roll with a mirror, a roller having a diameter of 450 mm and a width of 1500 mm was used. The cooling temperature of the roll was set to 70 ° C. The mirror-finished cooling roll is a metal cooling roll with a mirror finish (mirror finish) plated with hard chromium.

Further, as the above matte rubber roll, silica sand and silicic acid having a rubber hardness (based on JIS-K-6301: 1995) measured with a spring type JIS hardness meter of 70 Hs and a particle diameter of 31 to 37 μm. Glass particles containing 20 to 55% by mass were used. Further, the rubber roll had a diameter of 300 mm and a width of 1500 mm.

At the time of clamping, the mirror-finished cooling roll was in contact with the intermediate layer, and the matte rubber roll was in contact with the printable layer. The thickness of the obtained laminated resin film was 100 μm, and the internal haze was 13%.

(Production Example 2)
As a resin composition for the base material layer, a propylene homopolymer (manufactured by Nippon Polypro Co., Ltd., trade name: Novatec PP MA3U) 99.9% by mass, and a nucleating agent (manufactured by Nippon Polypro Co., Ltd., trade name: Novatec PP TX922A) A 0.1% by weight mixture was used. As the resin composition for the intermediate layer, an ethylene / hexene-1 copolymer (manufactured by Nippon Polyethylene Co., Ltd., trade name: Kernel KS340T) 92.6% by mass, an antistatic agent (manufactured by Nippon Polyethylene Co., Ltd., trade name: Novatec LL LX) A mixture of 4.2% by mass of AS and 3.2% by mass of an antiblocking agent (manufactured by Nippon Polyethylene Co., Ltd., trade name: Kernel KMB32F) was used. As a resin composition for a printable layer, propylene homopolymer (manufactured by Nippon Polypro Co., Ltd., trade name: Novatec PP FB3C) 70% by mass, and maleic acid-modified ethylene / vinyl acetate copolymer (manufactured by Nippon Polyethylene Co., Ltd., product) Name: Modic AP A515) A 30% by weight mixture was used.

Further, as a mat-like rubber roll, silica sand and silicate glass particles having a rubber hardness (conforming to JIS-K-6301: 1995) of 70 Hs and a particle diameter of 52 to 62 μm are contained at a ratio of 20 to 55% by mass. What was made to use was used. Further, the rubber roll had a diameter of 300 mm and a width of 1500 mm.

A laminated resin film was obtained in the same manner as in Production Example 1 except for these points. The thickness of the obtained laminated resin film was 100 μm, and the internal haze was 16%.

(Production Example 3)
As the resin composition for the base material layer, 100% by mass of a propylene random copolymer (manufactured by Nippon Polypro Co., Ltd., trade name: Novatec PP FW3E) was used. As the resin composition for the intermediate layer, an ethylene / hexene-1 copolymer (manufactured by Nippon Polyethylene Co., Ltd., trade name: Kernel KS340T) 92.6% by mass, an antistatic agent (manufactured by Nippon Polyethylene Co., Ltd., trade name: Novatec LL LX) A mixture of 4.2% by mass of AS and 3.2% by mass of an antiblocking agent (manufactured by Nippon Polyethylene Co., Ltd., trade name: Kernel KMB32F) was used. As a resin composition for the printable layer, 65% by mass of a propylene homopolymer (manufactured by Nippon Polypro Co., Ltd., trade name: Novatec PP FB3C) and a maleic acid-modified ethylene / vinyl acetate copolymer (manufactured by Nippon Polyethylene Co., Ltd., trade name) : Modic AP A515) A 35% by weight mixture was used.

The matte rubber roll contains silica sand and silicate glass particles having a rubber hardness (conforming to JIS K-6301: 1995) of 70 Hs and a particle diameter of 37 to 44 μm in a proportion of 20 to 55% by mass. Used. Further, the rubber roll had a diameter of 300 mm and a width of 1500 mm.

A laminated resin film was obtained in the same manner as in Production Example 1 except for these points. The thickness of the obtained laminated resin film was 100 μm, and the internal haze was 7%.

(Production Example 4)
As the resin composition for the intermediate layer, ethylene hexene-1 copolymer (manufactured by Nippon Polyethylene Co., Ltd., trade name: Kernel KS340T) 89.3% by mass, antistatic agent (manufactured by Nippon Polyethylene Co., Ltd., trade name: Novatec LL LX) -AS) A mixture of 7.1% by mass and 3.6% by mass of an antiblocking agent (trade name: Kernel KMB32F, manufactured by Nippon Polyethylene Co., Ltd.) was used. As a resin composition for a printable layer, 92% by mass of a propylene homopolymer (manufactured by Nippon Polypro Co., Ltd., trade name: Novatec PP MA3U) and calcium carbonate powder (manufactured by Bihoku Powder Chemical Co., Ltd., trade name: Softon 1000, average) (Particle size: 2.2 μm) A 8% by mass mixture was used.

Further, as the matte rubber roll, an embossed rubber roll having a rubber hardness (conforming to JIS K-6301: 1995) of 70 Hs and having 250 gravure-type embossing per inch was used. The embossed rubber roll had a diameter of 300 mm and a width of 1500 mm.

A laminated resin film was obtained in the same manner as in Production Example 1 except for these points. The thickness of the obtained laminated resin film was 100 μm, and the internal haze was 25%.

(Examples 1 to 3, Comparative Example 1)
Using a micro gravure coater on the surface of each laminated resin film obtained in Production Examples 1 to 4, an emulsion solution of maleic acid-modified ethylene / vinyl acetate copolymer (product name: EA, manufactured by Toyo Morton Co., Ltd.) -H700, heat of fusion: 44.3 J / g, solid content concentration: 50%). The coated layer obtained by drying the coated laminated resin film in an oven set at 95 ° C. was used as a seal layer. Thus, the in-mold labels of Examples 1 to 3 and Comparative Example 1 were obtained. The thickness of the seal layer in each in-mold label was 3 μm.

Next, the in-mold labels obtained in each Example and Comparative Example were punched into a rectangle having a long side of 8 cm and a short side of 6 cm, and using an inserter robot, a stretch blow molding machine (trade name: ASB- manufactured by Nissei ASB Co., Ltd.) 70DPH), an in-mold label was placed so that the printable layer was in contact with the mold (that is, the seal layer was facing the preform side). The label was installed in the mold so that the long side of the label was attached in parallel to the circumferential direction of the body of the molded product. The mold was cooled so that the surface temperature was in the range of 20 to 45 ° C.

Next, a preform obtained by injection molding of natural color polyethylene terephthalate resin was preheated to 95 ° C. and placed in a mold. After mold binding, the preform was stretch blow molded in a mold at a mold temperature of 45 ° C. for 1 second under a blow pressure of 2.5 MPa. Then, it cooled to 50 degreeC in 15 seconds. In this way, a molded article with a label was obtained.

Among the obtained molded articles with labels, the resin molded body was a container having a square body having a height of 12 cm and a side of about 7 cm. Table 1 summarizes the results of the adhesive strength and color difference between the label of the obtained molded article with label and the resin molded article, the average refractive index and crystallinity of the seal layer, and the haze value.

Example 4
Except for using an ethylene / vinyl acetate copolymer emulsion solution (product name: Lifebond HC-12, heat of fusion: 43.2 J / g) as a coating solution containing an olefin resin. In the same manner as in Example 1, an in-mold label and a molded product with a label were obtained. Table 1 summarizes the results of the adhesive strength and color difference between the label of the obtained molded article with label and the resin molded article, the average refractive index and crystallinity of the seal layer, and the haze value.

(Example 5)
As a coating solution containing an olefin resin, an ethylene / vinyl acetate copolymer hot lacquer (manufactured by Toyo Morton Co., Ltd., trade name: Tomoflex THS-4884-U, heat of fusion: 45.7 J / g, solid content concentration: An in-mold label and a molded article with a label were obtained in the same manner as in Example 1 except that 15%) was used. Table 1 summarizes the results of the adhesive strength and color difference between the label of the obtained molded article with label and the resin molded article, the average refractive index and crystallinity of the seal layer, and the haze value.

(Example 6)
In-mold as in Example 1, except that an emulsion solution of ethylene / methacrylic acid / acrylic acid ester copolymer (heat of fusion: 53.6 J / g) was used as the coating liquid containing the olefin resin. A label and a molded article with a label were obtained. Table 1 summarizes the results of the adhesive strength and color difference between the label of the obtained molded article with label and the resin molded article, the average refractive index and crystallinity of the seal layer, and the haze value. A coating solution containing an olefin resin was prepared according to the following procedure.

[Production example of coating liquid containing olefin resin]
40 kg of isopropanol (trade name: Tokuso IPA, manufactured by Tokuyama Corporation) was charged into a reactor having an internal volume of 150 L equipped with a cooler, a nitrogen introduction tube, a stirrer, a monomer dropping funnel, and a heating jacket.
While stirring isopropanol, 12.6 kg of N, N-dimethylaminoethyl methacrylate (manufactured by Sanyo Kasei Kogyo Co., Ltd., trade name: methacrylate DMA), butyl methacrylate (manufactured by Mitsubishi Rayon Co., Ltd., trade name: acrylate) B) 12.6 kg and higher alcohol methacrylic acid ester (Mitsubishi Rayon Co., Ltd., trade name: Acryester SL, a mixture of lauryl methacrylate and tridecyl methacrylate) were charged.

After the gas in the reactor was replaced with nitrogen, the mixture in the reactor was heated to 80 ° C. To the heated mixture, 0.3 kg of azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-60 (AIBN)) was added as a polymerization initiator to initiate polymerization. The polymerization time was 4 hours. During the polymerization, the reaction temperature was maintained at 80 ° C.
Thereafter, the copolymer obtained by polymerization was neutralized with 4.3 kg of glacial acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.). Further, while distilling off isopropanol, 48.3 kg of ion exchange water was added to the reactor, and the solvent was replaced, whereby the neutralized product of the cationic polymer emulsifier composed of the (meth) acrylic copolymer was obtained. An aqueous solution was obtained.

The aqueous solution obtained by the above procedure was used as a dispersion described later. The solid content concentration in the dispersion was 35% by mass. The (meth) acrylic copolymer had a weight average molecular weight of 40,000.

Next, using a twin screw extruder (manufactured by Nippon Steel Works, TEX30HSS), the olefin resin was melt-kneaded and emulsified to prepare a coating liquid containing the olefin resin. The melt kneading and emulsification of the olefin resin was performed according to the following procedure.

First, pellet-shaped olefin resin was supplied from a hopper to a twin-screw extruder. As the olefin-based resin, ethylene / methacrylic acid / acrylic acid ester copolymer resin (Mitsui / DuPont Polychemical Co., Ltd., trade name: Nucrel N035C) was used.
In a twin screw extruder, the resin was melted and kneaded under the conditions of a screw speed of 300 rpm and a cylinder temperature of 160 ° C. to 250 ° C. Then, said dispersion liquid was supplied from the injection port provided in the cylinder intermediate part of the twin-screw extruder. The amount of the dispersion added was 15 parts by mass with respect to 100 parts by mass of the olefin resin in terms of the solid content in the dispersion. The emulsification and dispersion of the olefin resin proceeded inside the twin screw extruder, and a white olefin copolymer emulsion solution was obtained from the outlet of the twin screw extruder.
The solid content concentration of the emulsion solution was 45% by mass, and the volume average particle size of the emulsion was 0.7 μm.

(Example 7)
The in-mold label and the in-mold label were the same as in Example 1 except that the polyethylene terephthalate preform was changed to a colored preform (Yoki Sangyo Co., Ltd., trade name: PET bottle preform, 33 g (brown)). A labeled molded product was obtained. Table 1 summarizes the results of the adhesive strength and color difference between the label of the obtained molded article with label and the resin molded article, the average refractive index and crystallinity of the seal layer, and the haze value.

(Comparative Example 2)
Except for using a modified styrene copolymer emulsion solution (trade name: Baron BL-1, manufactured by Daiichi Paint Co., Ltd., solid content concentration: 42.8%) instead of the olefin resin emulsion solution, In-mold labels and labeled molded products were obtained in the same manner as in Example 1. Table 1 summarizes the results of the adhesive strength and color difference between the label of the obtained molded article with label and the resin molded article, the average refractive index and crystallinity of the seal layer, and the haze value.

According to the in-mold label of the present invention, adhesion at a relatively low temperature (for example, 90 to 110 ° C., preferably 95 to 110 ° C.) among various molding methods, particularly required in stretch blow molding. Even under the conditions, the adhesive strength between the resin molded body and the in-mold label is sufficient, and the difference in appearance between the resin molded body and the in-mold label can be reduced due to unprecedented transparency. . As a result, a resin molded product in which the resin molded body and the in-mold label appear to be integrated can be produced.

As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

The execution order of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior”. It should be noted that they can be implemented in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for the sake of convenience, it means that it is essential to carry out in this order. is not.

1 in-mold label, 2 substrate layer, 3 seal layer, 10 in-mold label, 11 substrate layer, 12 seal layer, 13 intermediate layer, 20 in-mold label, 21 substrate layer, 22 seal layer, 23 intermediate layer, 24 printable layer, 30 resin molded product (labeled container), 31 resin molded body (container), 32 in-mold label, 33 body

Claims (15)

Comprising at least a base material layer and a sealing layer laminated on the surface of the base material layer,
The base material layer has an internal haze measured according to JIS-K-7136 of 0.1 to 20%,
The sealing layer is
Including olefin resins,
The heat of fusion is 10 to 55 J / g, and
The preform was heated to 95 ° C., introduced with 2.5 MPa compressed air, in-mold molded, cooled to 50 ° C. in 15 seconds, and the average refractive index when measured at 23 ° C. was 1. 50 to 1.60,
In-mold label. Comprising at least a base material layer and a sealing layer laminated on the surface of the base material layer,
The base material layer has an internal haze measured according to JIS-K-7136 of 0.1 to 20%,
The sealing layer is
Including olefin resins,
The heat of fusion is 10 to 55 J / g, and
The preform is heated to 95 ° C., introduced with 2.5 MPa pressure air, in-mold molded, cooled to 50 ° C. in 15 seconds, and the crystallinity when measured at 23 ° C. is 0 to 50%
In-mold label. Comprising at least a base material layer and a sealing layer laminated on the surface of the base material layer,
The base material layer has an internal haze measured according to JIS-K-7136 of 0.1 to 20%,
The sealing layer is
Including olefin resins,
The heat of fusion is 10 to 55 J / g, and
The preform is heated to 95 ° C., introduced with 2.5 MPa pressure air, in-mold molded, then cooled to 50 ° C. in 15 seconds, and adhered to the resin molded body when measured at 23 ° C. The strength is 100 to 1000 gf / 15 mm,
In-mold label. The base material layer includes at least one of a polypropylene resin and a polyester resin,
The in-mold label according to any one of claims 1 to 3. The base material layer is an unstretched film or a stretched film stretched in at least a uniaxial direction.
The in-mold label according to any one of claims 1 to 4. An intermediate layer containing an olefin resin is further provided between the base material layer and the seal layer,
The in-mold label according to any one of claims 1 to 5. The olefin resin includes a copolymer containing at least one of vinyl acetate, acrylic acid, and methacrylic acid, and ethylene as a comonomer.
The in-mold label according to any one of claims 1 to 6. The olefin resin includes at least one of a copolymer of ethylene and vinyl acetate, and a copolymer of maleic acid-modified ethylene and vinyl acetate.
The in-mold label according to claim 7. Transparent in the non-heated state and transparent in the post-heating state,
The in-mold label according to any one of claims 1 to 8. Opaque in the unheated state and transparent in the heated state,
The in-mold label according to any one of claims 1 to 8. The sealing layer is a coating layer formed by coating and drying a coating liquid containing the olefin resin on the surface of the base material layer,
The coating solution includes an olefin resin emulsion in which the olefin resin is dispersed in an aqueous medium.
The in-mold label according to claim 10. A printable layer is further provided on the surface of the base material layer opposite to the surface on the seal layer side,
The in-mold label according to any one of claims 1 to 11. A resin molded product comprising a resin molded body and the in-mold label according to any one of claims 1 to 12 attached to the resin molded body,
Measured according to JIS-K-7136, the difference in haze between the bonded part of the in-mold label and the non-sticked part of the resin molded product is 20% or less.
Plastic molded product. The resin molding includes one or more resins selected from the group consisting of polyester resins, polycarbonate resins, polystyrene resins, polypropylene resins, and polyethylene resins.
The resin molded product according to claim 13. A method for producing the resin molded product according to claim 13 or 14,
When the resin molded body is molded by a molding machine, the in-mold label disposed inside the molding machine includes a step of being attached to the resin molded body.
A method for producing a resin molded product.

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