JP6922288B2 - Hot melt adhesive for laminating and laminated film laminate using it - Google Patents

Description

The present invention relates to a hot melt adhesive having sufficient laminating strength with respect to a polypropylene film even if it is a thin film and having excellent transparency, and a composite film using the same.

As a packaging film for foods, medical products, cosmetics, etc., a composite film in which several types of functional films are bonded is used, and it is common to composite the functional films with a laminating adhesive. Is the target. In recent years, solvent-free laminating adhesives have been developed from the viewpoint of reducing the environmental load and improving the working environment. Patent Document 1 states that no chemical reaction is required, and that environmental and safety aspects are required. A solvent-free hot-melt type adhesive for laminating has been proposed.

However, in the adhesive of Patent Document 1, when the thickness of the adhesive is less than 5 μm (less than about 5 g / m ² ), the lamination strength becomes very low, and particularly for packaging film applications such as foods, medical products and cosmetics. The required performance could not be achieved.

JP 2013-08827

An object of the present invention is to provide a hot melt adhesive which has sufficient laminating strength for a film such as polypropylene and is excellent in transparency, coating unevenness, etc., and a laminated film laminate using the same. ..

That is, in the present invention, ethylene-propylene copolymer (A) is 20 to 70% by mass, hydrogenated adhesive resin (B) is 20 to 55% by mass, and wax (D) having a melting point of 120 to 160 ° C. is 1 to 10% by mass. Concerning hot melt adhesives for laminating, including.

The present invention further relates to the above-mentioned hot melt adhesive for laminating containing an ethylene polymer (C) other than (A).

Further, the present invention comprises 25 to 55% by mass of an ethylene-propylene copolymer (A), 25 to 50% by mass of a hydrogenated tackifier resin (B), 4 to 30% by mass of an ethylene polymer (C) other than (A), and The present invention relates to the above-mentioned hot melt adhesive for laminating, which contains 2 to 8% by mass of wax (D) having a melting point of 120 to 160 ° C.

Further, the present invention is for the above-mentioned laminate in which the mass ratio of the ethylene-propylene copolymer (A) and the ethylene polymer (C) other than (A) is (A) / (C) = 2.0 to 5.0. Regarding hot melt adhesives.

The present invention also relates to the hot melt adhesive for lamination, wherein the hydrogenated tackifier resin (B) is a hydrogenated product of at least one petroleum resin selected from the group consisting of alicyclics and aromatics.

The present invention also relates to a laminated film laminate obtained by laminating a first film base material and a second film base material with the above-mentioned hot melt adhesive for laminating.

Furthermore, the present invention relates to the above-mentioned laminated film laminate in which the first film base material and / or the second film base material is an unstretched polypropylene film.

According to the present invention, it is possible to provide a hot melt adhesive which has sufficient laminating strength with respect to a polypropylene film or the like and is excellent in transparency, coating unevenness, etc., and a laminated film laminate using the same.

Hereinafter, the constituent requirements of the hot melt adhesive of the present invention will be described in detail.

<Ethylene-propylene copolymer (A)>
The ethylene-propylene copolymer (A) used in the present invention has good adhesion to a polypropylene film and takes a long time to solidify from a molten state, so that it is most suitable for laminating a film after applying a thin film. If it does not contain ethylene, it becomes too hard and the adhesive strength is insufficient.
The ethylene-propylene copolymer (A) lacks adhesive strength to the polypropylene film when it is less than 20% by mass in 100% by mass of the hot melt adhesive for laminating, and 5 g / m ^{2 when it exceeds 70% by mass.} Since uniform coating cannot be performed with a thin film of less than 20% by mass, it is characterized by containing 20% by mass or more and 70% by mass or less (hereinafter, abbreviated as 20 to 70% by mass). It is preferably 25 to 55% by mass, more preferably 30 to 50% by mass. Further, the amount of propylene in the copolymer containing ethylene is preferably 50 mol% or more and 90 mol% or less, and more preferably 75 mol% or more and 85 mol% or less.

<Hydrogenated adhesive resin (B)>
By including the hydrogenated tackifier resin (B) in the present invention, the adhesive force to the polypropylene base material can be further improved. The water-added tackifier (B) lacks adhesive strength to the polypropylene film when it is less than 20% by mass in 100% by mass of the hot melt adhesive for laminating, and even if it exceeds 55% by mass, it is a hot melt adhesive. Is too hard and the adhesive force to the polypropylene film is insufficient. Therefore, it is characterized by containing 20% by mass or more and 55% by mass or less (hereinafter, abbreviated as 20 to 55% by mass). It is preferably 25 to 50% by mass, more preferably 30 to 50% by mass.

The water-hydrated tackifier resin (B) is, for example, a phenol resin, a modified phenol resin, a terpenphenol resin, a xylenephenol resin, a cyclopentadiene-phenol resin, a xylene resin, an aliphatic type, an alicyclic group type, an aromatic type, or the like. Petroleum resin, phenol-modified petroleum resin, α-methylpolystyrene resin, terpene resin hydrogenated is preferable, and aliphatic, alicyclic, aromatic petroleum resin, aromatic modified aliphatic petroleum A resin or an aromatic-modified alicyclic petroleum resin water-added is more preferable. If it is not hydrogenated, the transparency of the hot melt adhesive for laminating will deteriorate.

<Ethylene polymer (C) other than (A)>
In the present invention, by using the ethylene-propylene polymer (A) and the ethylene-based polymer (C) other than (A) in combination, it is possible to prevent the hot melt adhesive for lamination from becoming hard and to suppress the hardening of the hot melt adhesive for lamination in a low temperature atmosphere. It is preferable because the adhesive strength can be maintained. Further, the ethylene-based polymer (C) other than (A) has the effect of facilitating the compatibility between the hydrogenated tackifier (B) and the ethylene-propylene polymer (A), and improves the transparency of the laminated adhesive. It is preferable because it improves. The ethylene polymer (C) other than (A) is preferably 4% by mass or more and 30% by mass or less (hereinafter, abbreviated as 4 to 30% by mass) in 100% by mass of the hot melt adhesive for laminating. 25% by mass is more preferable, and 10 to 20% by mass is further preferable. As the ethylene polymer (C) other than (A), one type may be used, or two or more types may be used in combination.

As the ethylene-based polymer (C) other than (A), for example, low-density polyethylene, ultra-low-density polyethylene, ethylene-butene copolymer, ethylene-heptene copolymer, and ethylene-octene copolymer are preferable, and they are used alone. It may be used in or in combination of two or more.

<Wax (D) with a melting point of 120 to 160 ° C>
In the present invention, the wax (D) is characterized by having a melting point of 120 ° C. or higher and 160 ° C. or lower. When the contents are sealed with a composite film made of a hot melt adhesive for laminating, heat sealing is generally performed at a temperature of 120 ° C. to 160 ° C., but when the softening point is less than 110 ° C., the heat between the films causes heat sealing. Peeling occurs. The wax (D) having a softening point of 120 ° C. or higher and 160 ° C. or lower prevents peeling. There is no particular upper limit on the softening point, but it is preferably 160 ° C. or lower. In addition, peeling means that a coated product in which a plurality of base materials are laminated is peeled off between the base materials. The softening point of the present invention is a temperature determined by the method specified in JIS K 6863.

The wax (D) is 1% by mass or more and 10% by mass or less (hereinafter, abbreviated as 1 to 10% by mass) in 100% by mass of the hot melt adhesive for laminating, and 2% by mass or more and 8% by mass or less. More preferred. If it is 1% by mass or less, floating occurs due to heat sealing at a temperature of 120 ° C. to 160 ° C. If it exceeds 10% by mass, the laminating strength on the polypropylene film decreases.

Further, as the wax (D), polyethylene, polypropylene and the like can be mentioned. The wax may be used alone or in combination of two or more. The heat of the heat seal is generally 120 ° C. to 160 ° C., and polypropylene wax is particularly preferable in consideration of the softening point in order to withstand the wax.

<Additives>
The hot-melt adhesive of the present invention contains additives such as antioxidants, ultraviolet absorbers, light stabilizers, anti-adhesive agents, antibacterial agents, deodorants, and fragrances as long as the object of the invention is not impaired. It may be.

Examples of the antioxidants include pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] and octadecyl-3- (3,5-di-t-butyl-4-). Hydroxyphenyl) propionate, diethyl [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] phosphonate, 4,6-bis (octylthiomethyl) -o-cresol, ethylenebis (oxy) Ethylene) bis [3- (5-t-butyl-4-hydroxy-m-tolyl) propionate, tris (2,4-di-t-butylphenyl) phosphite, bis (2,4-di-t-butyl) Phenyl) Pentaerythritol diphosphite and the like can be mentioned. These may be used alone or in combination of two or more.

The above-mentioned phenolic antioxidants donate hydrogen to ROO (peroxy radicals) generated in the chain growth process of autoxidation to stabilize them, and themselves become stable phenoxy radicals protected by ortho-position substituents. It has a function as a radical trapping agent that stops the chain reaction, thereby effectively suppressing thermal deterioration of the resin composition. In particular, it becomes more excellent by using a phenolic antioxidant in combination with a lactone-based antioxidant or a vitamin E-based antioxidant having a faster radical trap reaction than the phenolic antioxidant. In addition, the above-mentioned phosphorus-based antioxidant has a function of non-radically decomposing peroxides and ROOH to stop the chain reaction of the autoxidation process, which effectively deteriorates the heat of the resin composition. Suppress.

The above-mentioned ultraviolet absorber is not particularly limited, and examples thereof include commonly used ones such as salicylic acid type, benzophenone type, and benzotriazole type. These may be used alone or in combination of two or more.

Examples of the above-mentioned light stabilizer include hindered amine-based light stabilizers that are usually used.

<Manufacturing of hot melt adhesive>
The method for producing the hot melt adhesive of the present invention is not particularly limited, and heat-mixing is performed using either a melting pot equipped with a roll, a Banbury mixer, a kneader, and a stirrer, or a single-screw or two-screw extruder. The hot melt method is desirable.

<Laminated film laminate (composite film laminate)>
Next, the configuration of the laminated film laminate using the hot melt adhesive for lamination of the present invention will be described. The film laminate of the present invention is a laminated film laminate obtained by laminating a first film base material and a second film base material with the hot melt adhesive for laminating of the present invention, and is a first film. / Hot melt adhesive layer / The composition of the second film may be included, and an undercoat layer may be provided between the first and second films and the hot melt adhesive or the like, or the first And a film or the like may be further laminated on the outside of the second film.

The first and second films are not particularly limited, but are film-like substrates produced from a thermoplastic resin that can be thermoformed by means such as extrusion molding, injection molding, blow molding, stretch blow molding, and draw molding. As the thermoplastic resin constituting the first and second films, there are olefin-based copolymers, polyesters, polyamides, styrene-based copolymers, vinyl chloride-based copolymers, acrylic-based copolymers, and the like. Examples thereof include polycarbonate, and olefin-based copolymers, polyesters, and polyamides are preferable.

Olefin-based copolymers include low-, medium- or high-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene-copolymer, ionomer, and ethylene-vinyl acetate copolymer. Combined, ethylene-vinyl alcohol copolymer and the like, as polyester, polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate / isophthalate, polyethylene naphthalate and the like, and as polyamide, nylon 6, nylon 6, 6, nylon 6, etc. 10. Polyamides such as metaxylylene adipamide and styrene-based copolymers include polystyrene, styrene-butadiene block copolymer, styrene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer (ABS resin) and the like. However, examples of the vinyl chloride-based copolymer include polyvinyl chloride and vinyl chloride-vinyl acetate copolymer, and examples of the acrylic-based copolymer include polymethyl methacrylate and methyl methacrylate / ethyl acrylate copolymer. Be done. These thermoplastic resins may be used alone or in combination of two or more.

Preferred thermoplastic resins include polyamide resins such as nylon 6, nylon 66 and nylon 46, aromatic polyester resins such as polyethylene terephthalate, polyethylene naphthalate, polytrimethylene terephthalate, polybutylene terephthalate and polybutylene naphthalate, and polylactic acid. Examples thereof include polyolefin resins such as aliphatic polyester resins, polypropylene and polyethylene, or mixtures thereof.

As the first film base material in the laminated film laminate of the present invention, a biaxially stretched thermoplastic resin film is preferable, and a biaxially stretched polypropylene (OPP) film is preferable. As the second film base material in the laminated film laminate of the present invention, those having a heat-sealing property in order to function as a heat-adhesive layer when forming a bag-shaped packaging bag or the like are preferable, and heat-sealing, high-frequency sealing, etc. Materials that can be used are used. For example, low density polyethylene, linear low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, polypropylene, ethylene-acrylic acid copolymer, ethylene-acrylate copolymer, ethylene-acrylate copolymer, etc. However, low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer film, and unstretched polypropylene are particularly preferably used.

Further, a gas barrier layer may be used for the purpose of long-term storage of the contents, and there is no particular limitation, but a layer such as polyvinyl alcohol, a partial saponified product of polyethylene-vinyl acetate, polyvinylidene chloride, or a polyacrylonitrile copolymer is provided. It may be used, or a film on which aluminum, silicon oxide or metal oxide (alumina) is vapor-deposited may be used.

The film laminate may have a print layer. The printing layer may be either the hot-melt adhesive layer side surface or the other surface of the first and second films, but the printed surface is printed on the adhesive layer side surface for designability and safety. Is preferable. Further, the first and second films may be subjected to corona treatment for the purpose of improving the adhesion of ink or the like.

The composite film laminate of the present invention is a first film base material such as OPP (biaxially stretched polypropylene film) by heating and melting a hot melt adhesive and using a gravure coater, a roll coater, a die coater, and a slit coater. It is preferable to apply it on top, attach it to a second film base material such as CPP (unstretched polypropylene film) that can be immediately heat-sealed, and press it with a pressure roll to make it, but CPP (unstretched polypropylene film) ) And the like, the film may be immediately bonded to the first film of OPP (biaxially stretched polypropylene film) and crimped with a pressure roll. Further, the hot melt adhesive may be once applied to a transferable roll such as a silicon roll, and then transferred to a propylene film for bonding. The amount of the hot melt adhesive applied ^{is preferably less than 5 g / m 2} , and more preferably 4 g / m ² or less from the viewpoint of flexibility. The composite film of the present invention can be used for packaging foods, medical products, cosmetics, etc. by heat sealing or the like.

Hereinafter, the present invention will be described in detail with reference to Examples, but these Examples are merely one aspect of the present invention, and the present invention is not limited to these Examples.
In the example, "parts" and "%" represent "parts by mass" and "% by mass".

<Manufacturing method of hot melt adhesive>
[Examples 1 to 20, Comparative Examples 1 to 17]
A polymer (copolymer), a tackifier, and a wax were added to a kneader equipped with a stirrer in the number of copies shown in Tables 1 and 2, and the mixture was stirred at 180 ° C. for 3 hours to prepare a hot melt adhesive. bottom.

<Manufacturing method of laminated laminate (composite film)>
[Examples 21-40, Comparative Examples 18-34]
The hot melt adhesives obtained in Examples and Comparative Examples were ^{applied to biaxially stretched polypropylene at about 4 g / m 2} using a gravure coater heated to 130 ° C., and immediately thereafter, non-axially stretched polypropylene and a roll pressure of 2.5 kgf were applied. A composite film was prepared by laminating and crimping with.

<Evaluation of laminated laminate>
The obtained laminated laminate was evaluated as follows. The results are shown in Tables 1 and 2.

[transparency]
The transparency of the composite film obtained by crimping the biaxially stretched polypropylene and the non-axially stretched polypropylene of the composite film with a hot melt adhesive was visually determined. △ The above is practical.
〇: Colorless and transparent △: Colorless and translucent ×: Opaque

[Uneven coating, foam residue]
With respect to the composite film in which the biaxially stretched polypropylene and the non-axially stretched polypropylene of the composite film were pressure-bonded with a hot melt adhesive, coating unevenness and foam residue were visually determined.
〇: The coated surface is smooth and there are no bubbles that can be visually confirmed. ×: The coated surface is uneven and bubbles are scattered.

[Laminate adhesive strength]
The composite film is cut into a size of 25 mm × 100 mm, a part of the adhesive portion between the biaxially stretched polypropylene and the non-axially stretched polypropylene is heated and peeled off, and the tensile tester is used to form a T-shape in an atmosphere of 23 ° C. It was set and peeled off in the T-shape at a speed of 200 mm / min, and the laminate adhesive strength was measured. △ The above is practical.
〇: 2.0N / 25mm or more Δ: 1.5N / 25mm or more, less than 2.0N / 25mm ×: less than 1.5N / 25mm

[Peeling and floating during heat sealing]
The composite film was cut into a size of 25 mm × 80 mm, and a set of two sheets were bonded together with non-axially stretched polypropylene, and a width of 25 mm × 20 mm was heat-sealed under the conditions of 140 ° C., 1 kgf, and 1 second. The peeling and floating of the hot melt adhesive adhering the biaxially stretched polypropylene and the non-axially stretched polypropylene were visually judged.
〇: No peeling or floating △: Peeling or floating is less than 10% of the total ×: Peeling or floating is 20% or more of the whole

[Heat seal strength: 23 ° C]
The heat-sealed sample was left at 23 ° C. 65% RH for 24 hours, set in a tensile tester so as to form a T shape in the same manner as in the evaluation of laminated adhesive strength, and biaxially stretched polypropylenes were placed at a speed of 200 mm / It was peeled off in the T-shape in minutes, and its heat seal strength was measured. △ The above is practical.
〇: 10N / 25mm or more Δ: 5N / 25mm or more and less than 10N / 25mm ×: 5N / 25mm or less

[Heat seal strength: low temperature 0 ° C]
Heat seal strength: The heat seal strength was measured in an atmosphere of 0 ° C. under the same peeling conditions as at 23 ° C. △ The above is practical.
〇: 10N / 25mm or more Δ: 5N / 25mm or more and less than 10N / 25mm ×: 5N / 25mm or less

The abbreviations in Table 1 are shown below.
Polymer 1: Ethylene-propylene copolymer polymer containing 83 mol% propylene 2: Ethylene-propylene copolymer polymer containing 78 mol% propylene 3: Ethylene-propylene copolymer polymer containing 58 mol% propylene 4: Low density Polyethylene polymer 5: Ethylene butene copolymer polymer 6: Ethylene octene copolymer polymer 7: Ethylene vinyl acetate copolymer (vinyl acetate content 14 wt%)
Polymer 8: Polybutene Polymer 9: Polypropylene

Adhesive imparting agent 1: Hydrophilic alicyclic petroleum resin tackifier 2: Hydrated aromatic petroleum resin tackifier 3: Hydrophobic terpene resin tackifier 4: Hydrophobicated aliphatic resin adhesive Additive 5: Water-hydrated aromatic-modified aliphatic petroleum resin tackifier 6: Water-hydrated aromatic-modified alicyclic petroleum resin tackifier 6: Rodin ester tackifier 7: α-methylstyrene resin tackifier Agent 8: Alicyclic petroleum resin tackifier 9: Aromatic petroleum resin tackifier 10: Copolymerization system of alicyclic and aromatic Petroleum resin tackifier 10: Terpen resin tackifier 11: Aromatic resin

Wax 1: Paraffin wax Melting point 68 ° C
Wax 2: Fischer-Tropsch wax Melting point 110 ° C
Wax 3: Polyethylene wax Melting point 110 ° C
Wax 4: Polyethylene wax Melting point 127 ° C
Wax 5: Polypropylene wax Melting point 156 ° C

From the results of Tables 1 and 2, the ethylene-propylene copolymer (A) 20 to 70% by mass, the hydrogenated adhesive resin (B) 20 to 55% by mass, and the wax (D) 1 having a melting point of 120 to 160 ° C. It was shown that the hot melt adhesive for laminating containing 10% by mass has sufficient laminating strength with respect to a film such as polypropylene, and is excellent in transparency, coating unevenness and the like.

Claims (6)

Hot for lamination containing 20 to 70% by mass of ethylene-propylene copolymer (A), 20 to 55% by mass of hydrogenated tackifier resin (B), and 1 to 10% by mass of wax (D) having a melting point of 120 to 160 ° C. It ’s a melt adhesive ,
Further, it contains an ethylene polymer (C) other than (A), and contains
A hot melt adhesive for laminating , wherein the wax (D) is polypropylene wax. Ethylene-propylene copolymer (A) 25 to 55% by mass, hydrogenated adhesive resin (B) 25 to 50% by mass, ethylene polymer (C) other than (A) 4 to 30% by mass, and melting point 120 to 120 to The hot melt adhesive for laminating according to claim 1 , which contains 2 to 8% by mass of wax (D) at 160 ° C. The invention according to claim 1 or 2 , wherein the mass ratio of the ethylene-propylene copolymer (A) to the ethylene polymer (C) other than (A) is (A) / (C) = 2.0 to 5.0. Hot melt adhesive for laminating. The hot melt for lamination according to any one of claims 1 to 3 , wherein the hydrogenated adhesive resin (B) is a hydrogenated product of at least one petroleum resin selected from the group consisting of alicyclics and aromatics. glue. A laminated film laminate obtained by laminating a first film base material and a second film base material with the hot melt adhesive for laminating according to any one of claims 1 to 4. The laminated film laminate according to claim 5 , wherein the first film base material and / or the second film base material is an unstretched polypropylene film.