JP3222936B2 - Multi-layer film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer film in which two or more layers are laminated, and more particularly to a multilayer film in which at least one of the outermost layers is a polyolefin film. 2. Description of the Related Art In recent years, many functions have been demanded for packaging films, and as one means for responding to such demands, a multilayer film has been attempted. The film materials used for multi-layering are diversified. Among them, the multi-layer film using a polyolefin-based film as the outermost layer has features such as easy processability, easy heat sealing, and water resistance. Therefore, it is widely used as a packaging film for food and various articles. The present invention relates to the improvement of a multilayer film using a polyolefin-based film as the outermost layer as described above.

[0002]

2. Description of the Related Art Polyolefin-based resins are inherently hydrophobic and have a strong chargeability because of their hydrophobicity. Multi-layer films using a polyolefin-based film formed from the polyolefin-based resin as the outermost layer are used in the processing step and the use stage. Many problems such as electrostatic shock and adhesion of dust are likely to occur. Therefore, in general, in order to solve these problems, as the outermost polyolefin-based film, a film containing various surfactants incorporated therein as an antistatic agent is used. On the other hand, as one means for forming a multilayer, an outermost layer of a polyolefin-based film is bonded to another film adjacent thereto with an adhesive. As such an adhesive, an adhesive such as a polyurethane-based, titanate-based, or imine-based adhesive is used. In many cases, a polyurethane-based adhesive having excellent adhesive strength is used.

However, surfactants known as kneading-type antistatic agents for polyolefin resins, such as alkylaminodiethanol, N-alkanol fatty acid amide, glycerin fatty acid monoester, alkylene glycol fatty acid ester, fatty acid Knead the group alcohol ethoxylate, etc., and make the formed polyolefin film as the outermost layer, and paste it with another film with a polyurethane adhesive to obtain the polyolefin film forming the outermost layer of the obtained multilayer film. There is a problem that the antistatic property is significantly reduced as compared with the case of the single layer of the polyolefin-based film. If a polyolefin-based film containing a large amount of a surfactant is used for the purpose of preventing such a decrease in the antistatic property, the decrease in the antistatic property can be prevented to some extent. In the film, there is a problem that the adhesive strength between the polyolefin-based film and another film adjacent thereto is reduced.

[0004]

An object of the present invention is to provide a polyolefin-based film in which at least one of the outermost layers contains a surfactant as an antistatic agent. The point is that the antistatic property of the polyolefin-based film is significantly reduced or the adhesive force between these films is reduced in a multilayer film bonded to another film adjacent thereto with a polyurethane-based adhesive.

[0005]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that a film containing a specific surfactant in a predetermined amount as an outermost polyolefin-based film is properly suitable. Was found.

That is, the present invention relates to a multilayer film in which two or more layers are laminated, wherein at least one of the outermost layers is an aliphatic monocarboxylic acid monoester of tetraol per 100 parts by weight of polyolefin resin. / Sulfonic acid type anionic surfactant = 90 / 10-60
/ 40 (weight ratio) with a surfactant of 0.05
The present invention relates to a multi-layer film characterized in that the film is a polyolefin-based film containing up to 2 parts by weight, and the polyolefin-based film is bonded to another film adjacent thereto with a polyurethane-based adhesive.

In the present invention, the outermost polyolefin film containing a surfactant includes: 1) an olefin homopolymer such as polyethylene or polypropylene;
Or 2) copolymers of ethylene or propylene with other vinyl monomers such as vinyl acetate, ethyl acrylate, acrylic acid, etc., obtained from these polyolefin resins by various film forming means. Among them, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, those obtained from ethylene-vinyl alcohol copolymer saponified ethylene-vinyl acetate copolymer among others preferable.

[0008] Among the surfactants contained in the outermost polyolefin-based film, the aliphatic monocarboxylic acid monoester of tetraol is a monoester derived from tetraol and aliphatic monocarboxylic acid. Examples of the tetraol used for deriving such an aliphatic monocarboxylic acid monoester of tetraol include (poly) ether tetraols such as ethylene glycol diglyceryl ether in addition to pentaerythritol, sorbitan, and diglycerin. . The aliphatic monocarboxylic acid used to derive such an aliphatic monocarboxylic acid monoester of tetraol has 8 to 20 carbon atoms.
And aliphatic monocarboxylic acids.

Of the aliphatic monocarboxylic acid monoesters of tetraol thus derived, sorbitan monoester and diglycerin monoester are preferred.

When an aliphatic monocarboxylic acid monoester of a polyol having a smaller number of hydroxy groups than that of a tetraol is used instead of the aliphatic monocarboxylic acid monoester of a tetraol, the final multilayer film can be obtained in the following manner. When the antistatic property of the polyolefin-based film of the outer layer is reduced and an aliphatic monocarboxylic acid monoester of a polyol having a larger number of hydroxy groups than tetraol is used, the polyolefin of the outermost layer in the finally obtained multilayer film The adhesive force between the base film and another film bonded to the base film with a polyurethane adhesive is reduced.

Among the surfactants contained in the outermost polyolefin film, sulfonic acid type anionic surfactants include: 1) sodium decyl sulfonate, sodium dodecyl sulfonate, lithium tetradecyl sulfonate, hexadecyl sulfone Alkali metal salts of alkyl sulfonic acids such as potassium silicate; 2) alkali metal salts of alkyl aryl sulfonic acids such as sodium butylbenzene sulfonate, sodium dodecyl benzene sulfonate, potassium octadecyl benzene sulfonate, sodium dibutyl naphthalene sulfonate; 3) dioctyl sulfosuccinate Acid sodium ester, lithium dibutylsulfosuccinate, sodium dodecylsulfoacetate, nonylphenoxy polyethylene glycol sulfoacetate potassium Although ester sulfonate alkali metal salts such beam and the like, alkali metal salts alkylsulfonic acids and alkylaryl sulfonic acid alkali metal salt is preferably Among them, in particular those having 12 to 18 carbon atoms preferably.

In the present invention, the outermost layer of the polyolefin-based film contains a surfactant composed of an aliphatic monocarboxylic acid monoester of tetraol and a sulfonic acid type anionic surfactant as described above. As the surfactant, aliphatic monocarboxylic acid monoester of tetraol / sulfonic acid type anionic surfactant =
One having a ratio of 90/10 to 60/40 (weight ratio) is used. This is because both the antistatic property and the adhesive strength as described above are compatible.

In the present invention, the content of the above-mentioned surfactant in the outermost layer of the polyolefin-based film is from 0.05 to 100 parts by weight of the polyolefin-based resin.
The amount is 2 parts by weight, preferably 0.1 to 1 part by weight, though it depends on the type and density of the polyolefin resin used. This is because both the antistatic property and the adhesive strength as described above are compatible.

The multilayer film of the present invention includes those having the above-mentioned surfactant-containing polyolefin-based film on only one side as the outermost layer and those having on both sides as the outermost layer. Other films bonded to the outermost polyolefin-based film with a polyurethane-based adhesive include 1) polyethylene, unstretched polypropylene,
Films such as biaxially oriented polypropylene and 2) films such as biaxially oriented nylon and polyethylene terephthalate. These other films may be used in a single layer or in a laminate.

Specific examples of the multilayer film of the present invention include:
Surfactant-containing polyethylene film / polyurethane-based adhesive / polyethylene film, surfactant-containing polyethylene film / polyurethane-based adhesive / biaxially oriented polypropylene film, surfactant-containing polyethylene film / polyurethane-based adhesive / polyethylene film /
Polyethylene film, unstretched polypropylene film containing surfactant / polyurethane-based adhesive / biaxially stretched polyethylene terephthalate film, unstretched polypropylene film containing surfactant / polyurethane-based adhesive / biaxially stretched nylon film, surfactant-containing ethylene Vinyl acetate film / polyurethane adhesive / biaxially stretched nylon film, surfactant-containing polyethylene film / polyurethane adhesive / polyethylene film / polyurethane adhesive / polyethylene film, surfactant-containing polyethylene film / polyurethane adhesive / Examples include polyethylene film / polyurethane-based adhesive / polyethylene film containing surfactant.

The surfactant-containing polyolefin film forming the outermost layer is formed from a polyolefin resin melt containing a predetermined amount of the above-described surfactant by a known method, for example, an inflation method or a casting method. Is obtained. As a method of incorporating the surfactant into the polyolefin-based film, for example, a method of mixing the surfactant with pellets of the polyolefin-based resin, a master chip of the surfactant-containing polyolefin-based resin is prepared in advance and used. There are methods.

In the multilayer film of the present invention, the polyurethane adhesive is a known adhesive obtained by a urethane-forming reaction of a polyisocyanate and a polyol. For bonding the outermost surfactant-containing polyolefin-based film to another film adjacent thereto, a known polyurethane-based adhesive and its adhesive formulation can be applied. Although the present invention is not particularly limited with respect to the thickness of the polyurethane adhesive, that is, the coating amount per unit area of the film, it is usually 0.1 mm in the extrusion lamination method in which the molten resin is laminated on the base film coated with the polyurethane adhesive. 1~0.5g / m ² (solid content), and a 1.0 to 5.0 g / m ² (solid content) in the dry lamination method. The effect of the present invention is more remarkable as the amount of the polyurethane-based adhesive applied is larger, and is particularly effective in a dry lamination method. Hereinafter, the configuration and effect of the present invention will be described more specifically with reference to examples and comparative examples.

[0018]

EXAMPLES Test Category 1 Preparation of low-density polyethylene film containing surfactant Low-density polyethylene chip (melt flow index 14.0 g / 10 min, density 0.924 g / cm ³ , trade name Mitsubishi Polyethylene YK-60) (Mitsubishi Yuka Co., Ltd.) and 6 parts by weight of the surfactants shown in Tables 1 and 2 were mixed to prepare a polyethylene master chip containing the surfactant. Then, using this polyethylene master chip and the above-mentioned low-density polyethylene chip, both were dry-blended so as to have the surfactant content shown in Tables 1 and 2, and the thickness was 30 μm using an inflation film forming machine. Of low-density polyethylene films (E-1 to E-4, R-1 to R-11) containing a surfactant.

Preparation of unstretched polypropylene film containing surfactant Polypropylene chip (melt flow index 7.
5 g / 10 min, density 0.90 g / cm ³ , trade name Sumitomo Noblen FA-6411, manufactured by Sumitomo Chemical Co., Ltd.) and the above-mentioned surfactant-containing polyethylene master chip, and containing the surfactant described below. In the same manner as in the case of the low-density polyethylene film, the polypropylene film containing the surfactant shown in Tables 3 and 4 (P
-1 to P-2, R-12 to R-15) were prepared.

Corona discharge treatment One surface of the surfactant-containing polyolefin film thus obtained is subjected to corona discharge treatment to obtain a corona discharge treated film having a corona discharge treated surface having a critical surface tension of 39 to 41 dynes.cm. Was. With respect to this corona discharge treated film, the surface specific electric resistance of the untreated surface of the corona discharge was measured, and the results are shown in Tables 1 to 4.

Test Category 2 Examples 1-4 and Comparative Examples 1-11 Takerac A-515 and Takenate A-50 (both trade names, manufactured by Takeda Pharmaceutical Co., Ltd.) were used as polyurethane-based adhesives. 515 / Takenate A-5
An ethyl acetate solution having a total solid content of 20% by weight was prepared so that the ratio of 0 was 10/1 (weight ratio). This ethyl acetate solution was uniformly applied to one surface of a biaxially stretched polyethylene terephthalate film (thickness: 25 μm, trade name: ester E5100, manufactured by Toyobo Co., Ltd.) so as to have a solid content of 3.5 g / m ³ , and air-dried. did. Then, the surface of the biaxially stretched polyethylene terephthalate film to which the polyurethane-based adhesive was applied and the surface of the low-density polyethylene film containing the surfactant obtained in Test Category 1 which had been subjected to corona discharge treatment were bonded together, and placed in a 40 ° C. thermostat for 48 hours. This was left to obtain a multilayer film.

Examples 5-6, Comparative Examples 12-15 Ethylene-vinyl alcohol copolymer film (thickness 1
A polyurethane-based adhesive was uniformly applied to both surfaces of 2 μm (trade name: EVAL EF-F, manufactured by Kuraray Co., Ltd.) in the same manner as in Examples 1 to 4, and air-dried. Then, the corona discharge-treated surface of the low-density polyethylene film containing the surfactant obtained in Test Category 1 was attached to both surfaces of the ethylene-vinyl alcohol copolymer film coated with the polyurethane-based adhesive, and the following Examples 1 to 5 were further applied. In the same manner as in the case of No. 4, a multilayer film was obtained.

Examples 7 to 8 and Comparative Examples 16 to 19 One side of a biaxially stretched polypropylene film (thickness: 20 μm, trade name: Pyren P-2102, manufactured by Toyobo Co., Ltd.) was subjected to corona treatment in the same manner as in Test Category 1. A discharge treatment was performed, and a polyurethane-based adhesive was uniformly applied to the corona discharge treated surface in the same manner as in Examples 1 to 4, and air-dried. Then, the corona-discharge-treated surface of the polypropylene film containing the surfactant obtained in Test Category 1 was attached to the polyurethane-based adhesive-coated surface of the biaxially stretched polypropylene film, and further in the same manner as in Examples 1-4. A multilayer film was obtained.

For each of the multilayer films of Examples and Comparative Examples, the surface specific electric resistance value of the surfactant-containing polyolefin film forming the outermost layer, and the surfactant-containing polyolefin film and a polyurethane-based adhesive were used. The adhesive strength between the laminated films was measured by the following measuring method, and the results are shown in Tables 1 to 4.

· Measurement method · · · Surface specific electric resistance: After leaving the sample in a constant temperature and humidity room at 23 ° C and 65% RH for 48 hours, a super insulation meter SM-5E was used.
It was measured using a mold (manufactured by Toa Denpa Kogyo KK). ··· Adhesive strength: After leaving the sample in a constant temperature and humidity room at 23 ° C. × 65% RH for 48 hours, using a universal tensile tester UTM-3 type (manufactured by Orientec), the tensile speed is 300 mm.
The T-shaped peel strength (width 15 mm) was measured at / min.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

In Tables 1 to 4, the amount of surfactant (weight ratio): polyolefin resin 1
Content ratio per 00 parts by weight DGMS: diglycerin monostearate HDS-Na: sodium hexadecylsulfonate SML: sorbitan monolaurate TeGMS: tetraglycerin monostearate DBS-Na: sodium dodecylbenzenesulfonate GMS: glycerin monostearate Rate DeGML: Decaglycerin monolaurate TGDL: Triglycerin dilaurate LDPE: Low density polyethylene PP: Polypropylene HDPE: High density polyethylene PET: Biaxially oriented polyethylene terephthalate film EVOH: Ethylene-vinyl alcohol copolymer film OPP: Biaxially oriented polypropylene Film NY: Biaxially stretched nylon film AD: Polyurethane adhesive

[0031]

As is clear from the results of Tables 1 to 4, in the present invention described above, at least one of the outermost layers is a polyolefin film containing a surfactant as an antistatic agent. In a multilayer film in which the polyolefin-based film is bonded to another film adjacent to the polyolefin-based film with a polyurethane-based adhesive, both the antistatic property of the polyolefin-based film and the adhesive force between these films are compatible. There is an effect that can be.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-334449 (JP, A) JP-A-3-142218 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (2)

(57) [Claims] 1. A multilayer film in which two or more layers are laminated, wherein at least one of the outermost layers is a tetraol per 100 parts by weight of a polyolefin resin.
Aliphatic monocarboxylic acid monoester / sulfonic acid type anionic surfactant = 90/10 to 60/40 (weight ratio)
A polyolefin film containing a surfactant having a ratio of 0.05 to 2 parts by weight, and the polyolefin film is bonded to another film adjacent thereto with a polyurethane adhesive. Multilayer film. 2. A multilayer film of claim 1 Symbol placement sulfonate type anionic surfactant is an alkyl sulfonate alkali metal salt or an alkyl aryl sulfonic acid alkali metal salt.