JP5213008B2 - Heat-sealable coating material, membrane and method for producing the same, laminate film, and bag - Google Patents

Description

  The present invention relates to a heat-sealable coating material, a film and a production method thereof, a laminate film, and a bag.

  Thermoplastic resins, such as resins derived from non-petroleum raw materials represented by polylactic acid, have received attention for their biodegradability, and have been improved from the composition and processing points. Biodegradable films, sheets, containers Development of (molded products) and the like is being actively conducted.

  On the other hand, in order to form a packaging bag body, it is generally necessary to provide a sealant film having heat sealing properties, and synthetic resins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer are used as the sealant film. (Japanese Patent Laid-Open No. 2001-278354). If this sealant film is formed from a biodegradable material, the burden on the environment can be further reduced.

Examples of efforts to reduce the environmental impact of sealant membranes include heat-sealability using low-melting-point polylactic acid as the sealant layer by adjusting the crystallinity during polylactic acid film formation and controlling the temperature at which it substantially melts. There is a polylactic acid film (Japanese Patent Laid-Open No. 2006-213062). Although it is preferable in terms of biodegradability of the obtained heat-sealable film itself, it is considered that there is room for further improvement in view of further easy adhesion and low environmental load during the production of the heat-sealable coating material itself. .
JP 2001-278354 A JP 2006-213062 A

  An object of the present invention is to provide a heat-sealable coating material that has a sufficient heat-sealing strength and can form an environmentally friendly laminate film.

  Moreover, the objective of this invention is providing the film | membrane obtained using the said heat-sealable coating material, its manufacturing method, a laminated body film, and a bag.

  The heat-sealable coating material according to one embodiment of the present invention contains egg white protein, a plasticizer, and an aqueous medium.

  In the heat-sealable coating material, the egg white protein may be chicken egg white and / or protein derived from egg white.

  In the heat sealable coating material, the plasticizer may be urea.

  The heat-sealable coating material can further include an adhesion imparting agent. In this case, the adhesion-imparting agent can be a polyhydric alcohol.

  The film | membrane which concerns on 1 aspect of this invention is obtained by removing an aqueous medium from the said heat-sealable coating material.

  In the film according to one embodiment of the present invention, the above film is provided on at least a part of the base film.

  The bag according to one embodiment of the present invention includes a base film and a seal portion that bonds the base films in a state where the base films are in contact with each other, and the seal portion is provided with the film. It is obtained by heating the film installation part in a state where the film installation parts are in contact with each other.

  The method for producing a film according to one aspect of the present invention includes a step of applying a heat-sealable coating material containing egg white protein, a plasticizer, and an aqueous medium to a substrate to form a coating film, and the coating film is aqueous from the coating film. Removing the medium.

  Since the heat coating material has sufficient heat seal strength and contains a biodegradable material such as egg white protein, the load on the environment is small. Therefore, according to the bag body and the laminated body film, since the film obtained using the heat-sealable coating material is included, the bag body has sufficient heat-sealing strength and has a low environmental load.

  Hereinafter, a heat-sealable coating material according to an embodiment of the present invention, a film obtained using the coating material, a manufacturing method thereof, a laminate film, and a bag will be described.

1. Heat-sealable coating material The heat-sealable coating material which concerns on one Embodiment of this invention contains egg white protein, a plasticizer, and an aqueous medium. In the present invention, “heat sealability” refers to the property that the heated portion is thermally fused by applying pressure while heating.

1.1. Egg white protein The egg white protein is preferably, for example, chicken egg white and / or protein derived from egg white. From the viewpoint of economy, it is more preferable that the egg white protein is chicken egg white.

  Examples of the egg white that can be used include raw egg white, frozen egg white, dried egg white, and egg white from which a specific egg white protein (eg, lysozyme) has been removed. Here, the raw egg white means one obtained by dividing a chicken egg or the like and separating the egg yolk. Further, the egg white may be subjected to a desugaring process.

  Examples of the protein derived from chicken egg white include ovalbumin, ovotransferrin, ovomucoid, lysozyme, ovomucin, ovoglobulin, ovoglycoprotein, ovoinhibitor, ovomacroglobulin, ovoflavoprotein, avicin, cystatin and the like. One or more of these egg white proteins can be used in combination. Moreover, you may use the hydrolyzate (egg white peptide) of these egg white proteins as egg white protein.

  The amount of egg white protein (in terms of solid content) used is preferably 40 to 90 mass%, more preferably 60 to 80 mass%, based on the total amount of components excluding the aqueous medium in the heat-sealable coating material. preferable. If the amount of egg white protein used is less than 40% by mass, tack may remain on the sealant film after drying. On the other hand, if it exceeds 90% by mass, the amount of plasticizer or adhesion-imparting agent is reduced, resulting in heat. The sealing performance may be poor.

1.2. Plasticizer As the plasticizer, urea is preferable. By using urea as the plasticizer, the egg white protein can be dechained very efficiently, and the cohesive strength of the sealant film can be improved by entanglement between the egg white protein molecules. Moreover, as a plasticizer, you may utilize sodium dodecyl sulfate, guanidine hydrochloride, etc., for example. Furthermore, known plasticizers such as phthalic acid ester, adipic acid ester, phosphoric acid ester, sepacic acid ester, trimellitic acid ester, citric acid ester and fatty acid ester may be used in combination with urea.

  The amount of the plasticizer used is preferably 3 to 20% by mass, more preferably 5 to 10% by mass, based on the total amount of components excluding the aqueous medium in the heat-sealable coating material. If the amount of the plasticizer used is less than 3% by mass, the effect of releasing the egg white protein by the plasticizer may be poor, and the cohesive strength of the sealant film may not increase. On the other hand, if the amount exceeds 20% by mass, the sealant film after drying May remain tacky.

1.3. Aqueous medium Examples of the aqueous medium include water and an organic solvent compatible with water. Examples of water-compatible organic solvents include alcohol solvents (eg, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, etc. monohydric alcohols having 1 to 4 carbon atoms). ). Among these, as an aqueous medium, water is more preferable at the point which can suppress modification | denaturation of egg white protein. As will be described later, when the heating temperature at the time of forming the film exceeds 80 ° C., the egg white protein may be denatured. Therefore, considering the ease of removing the aqueous medium, the aqueous medium has a relatively low boiling point (for example, It is desirable that the boiling point is 120 ° C. or less, or that the vapor pressure at the heating temperature is relatively large.

  The amount of the aqueous medium used is preferably 50 to 95% by mass and more preferably 60 to 80% by mass with respect to the total amount of the heat-sealable coating material. If the amount of the aqueous medium used is less than 50% by mass, the viscosity of the coating material becomes high, so that a sealant film having a uniform thickness may not be obtained. In some cases, the sealant film to be formed may be thin, and in order to obtain sufficient heat seal strength, overcoating may be required, and the efficiency of film formation may be reduced.

1.4. Other components The heat-sealable coating material according to the present embodiment may further contain an adhesion-imparting agent. By using an adhesiveness imparting agent, the adhesiveness of the heat-sealable coating material according to this embodiment can be further enhanced.

  The adhesiveness imparting agent is preferably a polyhydric alcohol, for example. The polyhydric alcohol is a compound having two or more hydroxyl groups in one molecule, such as glycerin, polyglycerin, triethanolamine, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol (PEG), Propylene glycol, dipropylene glycol, polypropylene glycol, 1,3-butylene glycol, pentylene glycol, 1,1,1-trimethylolpropane, pentaerythritol, neopentyl glycol, diethanolamine, sugar alcohol (sorbitol, xylitol, mannitol, erythritol ) And polyvinyl alcohol (PVA), and these can be used alone or in combination of two or more.

  The amount of the adhesion-imparting agent used is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, based on the total amount of components excluding the aqueous medium in the heat-sealable coating material. When the amount of the adhesion-imparting agent used is less than 5% by mass, the heat seal strength of the sealant film may be poor. On the other hand, when it exceeds 50% by mass, tack may remain on the sealant film after drying.

2. MEMBRANE AND ITS MANUFACTURING METHOD, LAMINATE FILM, AND BAG BODY A membrane according to an embodiment of the present invention, a manufacturing method thereof, a laminate film, and a bag body are manufactured using the heat-sealable coating material according to this embodiment. Is done.

  The film (sealant film) according to this embodiment has sufficient heat seal strength and is excellent in transparency and adhesion. Preferably, the film according to the present embodiment has a heat seal strength of 3 N / 15 mm width or more measured by a heat seal strength evaluation method described in Examples described later.

2.1. Film and production method thereof The film according to this embodiment is obtained by removing the aqueous medium from the heat-sealable coating material according to this embodiment. More specifically, the film manufacturing method according to the present embodiment includes a step of applying a heat-sealable coating material containing egg white protein, a plasticizer, and an aqueous medium to a substrate to form a coating film, and a coating method. Removing the aqueous medium from the membrane.

2.1.1. Step of forming a coating film In the step of forming a coating film, the base material to which the heat-sealable coating material according to this embodiment is applied is not particularly limited. For example, plastic film, paper, fiber, wood board, metal film (for example, Aluminum film).

  The plastic film may be made of a thermoplastic plastic. Examples of the thermoplastic plastic include polyethylene, polypropylene, polybutylene, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyethylene terephthalate, polyethylene naphthalate, polyamide, polyacrylonitrile, and combinations thereof.

  The plastic film is more preferably made of a biodegradable plastic. Biodegradable plastics refer to plastics that have the property of being degraded by microorganisms. Examples of the biodegradable plastic include polylactic acid, lactic acid-butylene succinate copolymer, cellulose, cellulose acetate, chitin, chitosan, cellulose-chitosan-starch film, polyhydroxybutyrate, hydroxybutyrate-hydroxyhexano Copolymer, polyvinyl alcohol, polyglycolic acid, polybutylene succinate, polyethylene succinate, butylene succinate-adipate copolymer, butylene succinate-carbonate copolymer, polycaprolactone, caprolactone-butylene succinate copolymer , Ethylene terephthalate-succinate copolymer, butylene adipate-terephthalate copolymer, and tetramethylene adipate-terephthalate copolymer. Since the base film is made of a biodegradable plastic, the entire laminate film and bag according to the present embodiment can be made of a biodegradable material, so that the burden on the environment can be reduced.

  The thickness of the coating film is appropriately determined according to the amount of the aqueous medium contained and the required heat seal strength. Moreover, the method of apply | coating the heat-sealable coating material which concerns on this embodiment to a base material can use the bar-coat method, a spin coat method, the dipping method, the roll coat method, the spray method etc., for example.

2.1.2. Step of Removing Aqueous Medium The step of removing the aqueous medium from the coating film can be performed by, for example, heating, decompression with a vacuum pump, or a combination thereof.

  When removing an aqueous medium from a coating film by heating, it can carry out by heating a coating film at 30-80 degreeC for 0.1 to 30 minutes. Here, if the heating temperature of the coating film exceeds 80 ° C., the egg white protein may be denatured and a uniform coating film may not be obtained.

  The film | membrane which concerns on this embodiment is obtained by removing an aqueous medium from a coating film. Although the thickness of the film | membrane obtained is suitably determined according to the heat seal intensity | strength requested | required of a film | membrane, it is preferable normally that it is 2-50 micrometers.

2.2. Laminated body film The laminated body film which concerns on one Embodiment of this invention is provided with the film | membrane which concerns on this embodiment in at least one part of a base film. That is, the film | membrane which concerns on this embodiment can be provided in the single side | surface or both surfaces of a base film. The base film can be made of the materials exemplified above as the base material. The laminated body which concerns on this embodiment can be used, and the bag body mentioned later can be manufactured.

2.3. Bag body The bag body which concerns on one Embodiment of this invention is shown in FIG. In addition, the shape and structure of the bag body which concerns on this embodiment are not limited to the bag body shown in FIG.

  FIG. 1 is a plan view schematically showing a bag body according to the present embodiment. Moreover, Fig.2 (a) is a top view which shows typically the laminated body film used for manufacture of the bag body shown in FIG. 1, FIG.2 (b) is AA 'of Fig.2 (a). It is a figure which shows the cross section cut | disconnected along the direction in the direction perpendicular | vertical to drawing.

  Three-side seal packaging is applied to the bag body 10 according to the present embodiment, and as shown in FIG. 1, the base film 1 and a seal that adheres the base film 1 to each other in a state where the base films 1 are in contact with each other. Part 13a, 13b, 13c.

The bag 10 shown in FIG. 1 can be manufactured using the laminated body film 1 shown in FIG. 2 (a) and FIG.2 (b). The laminate film 1 includes a base film 2 and film installation portions 3a, 3b ₁ , 3b ₂ , 3c provided on the surface of the base film. In the laminate film 1 shown in FIG. 2, the film installation portions 3 a, 3 b ₁ , 3 b ₂ , 3 c are provided at the edge of the upper surface of the base film 2. Film setting section 3a, the 3b 1, 3b _{2, 3c,} film obtained by removing the aqueous medium is provided from the heat-sealable coating material according to the present embodiment.

The seal portion 13b is formed by folding the base film 1 (see FIG. 2A) so that the membrane setting portion 3b ₁ and the membrane setting portion 3b ₂ face each other, and the membrane setting portion 3b ₁ and the membrane setting portion 3b. ₂ is obtained by heating. Moreover, the seal | sticker part 13a is obtained by heating the film | membrane installation part 3a in the state which folded up the base film 1 so that the film | membrane installation parts 3a may oppose. Furthermore, the seal part 13c is obtained by heating the film installation part 3c in a state where the base film 1 is folded so that the film installation parts 3c face each other.

The bag 10 shown in FIG. 1 can be manufactured by the following method. First, the film installation parts 3b ₁ , 3b ₂ in a state where the film installation parts 3b ₁ , 3b _{2 of the} laminate film 1 are overlapped and folded in the lateral direction (parallel to the line AA ′) in FIG. Is heated to form the seal portion 13b shown in FIG. Next, by placing the seal portion 13b at the position shown in FIG. 1 and heating the membrane setting portion 3a in a state where the membrane setting portions 3a are overlapped, the seal portion 13a shown in FIG. 1 is formed, Furthermore, the film | membrane installation part 3c is heated in the state which piled up the film | membrane installation parts 3c, and the seal | sticker part 13c shown in FIG. 1 is formed. The order of forming the seal portions 13a, 13b, and 13c is not limited to this.

  The heating temperature when forming the seal portion is preferably 100 to 200 ° C. If the temperature is less than 100 ° C, the heat seal strength of the seal portion may not be sufficient. On the other hand, if the temperature exceeds 200 ° C, the substrate material may be affected, such as bending. . In particular, when the base film is made of polylactic acid, the heating temperature when forming the seal portion is preferably 100 to 130 ° C.

  The bag body 10 may be a packaging bag body. That is, although not shown in FIG. 1, the bag 10 may be filled with contents. In this case, the bag 10 can be filled with contents by automatic packaging. Although the kind of content is not specifically limited, For example, food, a pharmaceutical, cosmetics, and the container which stores these are mentioned. The means for automatic packaging is not particularly limited, but other than the above-described pillow seal packaging (vertical type, horizontal type), for example, three-side seal packaging, four-side seal packaging, shrink packaging, and stretch packaging can be applied.

3. EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.

3.1. Example 1
3.1.1. Preparation of coating material Using a mechanical stirrer in a beaker, 100 g of distilled water and 3 g (10 parts by mass) of urea as a plasticizer were mixed at room temperature for 3 minutes. Next, 30 g (100 parts by mass) of egg white protein (trade name “dried egg white K type”, manufactured by QP Corporation) was added and further stirred for 20 minutes. Thereafter, 3 g (10 parts by mass) of glycerin and 9 g (30 parts by mass) of polyethylene glycol # 2009 were added as plasticizers, and the mixture was stirred for 20 minutes with a mechanical stirrer, and then stirred for 20 minutes at 6000 rpm using a homomixer. did. Finally, a coating material of Example 1 was obtained by performing a treatment for 2 minutes of kneading and 2 minutes of defoaming using a rotating / revolving mixer. In the coating material of Example 1, the concentration of the components excluding the aqueous medium was 31% by mass.

3.1.2. Manufacture of sealant film (Manufacture of laminate film)
A UV treatment (low pressure mercury lamp, irradiation for 10 minutes) was performed, and the coating material obtained by the above process was applied onto a cellophane film having a film thickness of 25 μm to form a coating film. Next, the cellophane film on which the coating film was formed was allowed to stand in a hot air dryer at 50 ° C. for 5 minutes to remove the aqueous medium, thereby forming a sealant film on the cellophane film. The laminated body film was manufactured according to the above process. The obtained laminated film was subjected to various evaluations shown below. In addition, the thickness of the sealant film in the obtained laminate film was 10 μm.

3.1.3. Evaluation method 3.1.3-1. Adhesiveness The sealant films obtained in each of the examples and comparative examples were evaluated by visual observation for the presence or absence of peeling from the substrate after leaving at 180 ° C. for 30 minutes. In Table 1, “A” indicates that the peeling of the sealant film is not confirmed, and “B” indicates that the peeling of the sealant film is confirmed.

3.1.3-2. Transparency (underground transparency)
The transparency (underground permeability) of the film was evaluated by visual observation. In Table 1, “A” indicates the case where the sealant film has high transparency (base permeability), and “B” indicates the case where the sealant film has low transparency (base permeability) and is cloudy.

3.1.3-3. Heat seal strength The heat seal strength was measured in accordance with JIS standards (Test method for heat-sealed soft packaging bags and semi-rigid containers: JIS Z0238). Specifically, the heat seal strength was evaluated by the following method.

  First, from the laminate film obtained in each example and comparative example, two strip-shaped films having a width of 15 mm are cut out, and the two films are formed so that the surfaces on which the sealant film is formed face each other. The test pieces were arranged and sealed at one end of the two films to form a seal portion.

  The sealer used was an impulse sealer FI-300 (manufactured by Fuji Impulse Co., Ltd.), and the sealing conditions were voltage: 100 V, contact temperature: 160 ° C., and seal width: 5 mm. The sealing time was about 0.75 seconds.

  Tensilon (trade name “RTC-1250A”, manufactured by ORIENTEC) was used to measure the seal strength of the test piece. First, the two pieces of film were opened at 180 ° with the seal portion of the test piece at the center, and both ends of the two films were sandwiched using a tensilon gripping jig. A tensile load was applied until the seal part was completely peeled off, and the maximum load [N / 15 mm width] was obtained. The value of this maximum load was defined as the heat seal strength of the test piece. At this time, the pulling speed was 300 mm / min.

3.2. Example 2 and Comparative Examples 1 and 2
The coating materials of Example 2 and Comparative Examples 1 and 2 were prepared in the same manner as in Example 1 except that the composition of each component when preparing the coating material was as shown in Table 1. In addition, using the coating materials of Example 2 and Comparative Examples 1 and 2, the films of Example 2 and Comparative Examples 1 and 2 were formed in the same manner as in Example 1, and these films were used in Example 1. Evaluation was carried out in the same manner as above. The results are shown in Table 1. In Table 1, the units of egg white protein, plasticizer, adhesiveness imparting agent, and aqueous medium are parts by mass.

3.3. Discussion As shown in Table 1, it can be understood that the films obtained in Examples 1 and 2 have sufficient heat seal strength and are excellent in transparency and adhesion. On the other hand, in Comparative Example 1, the amount of egg white protein used is small, and tack remains after the drying step, so that it cannot function as a sealant film. On the other hand, in Comparative Example 2, since urea is not used as a plasticizer, heat seal strength is not sufficient, and it is estimated that transparency and adhesion are poor.

It is a top view which shows typically the bag which concerns on one Embodiment of this invention. Fig.2 (a) is a top view which shows typically the laminated body film used for manufacture of the bag body shown in FIG. 1, FIG.2 (b) follows AA 'of Fig.2 (a). It is a figure which shows the cross section cut | disconnected by the direction orthogonal to drawing.

Explanation of symbols

1 the laminate film 2 base film _{3a, 3b 1, 3b 2,} 3c film setting section (sealant film)
10 Bag 13a, 13b, 13c Seal part

Claims (6)

A heat-sealable coating material containing egg white protein, urea , polyhydric alcohol and an aqueous medium.   The heat-sealable coating material according to claim 1, wherein the egg white protein is a protein derived from chicken egg white and / or egg egg white.   The film | membrane obtained by removing an aqueous medium from the heat-sealable coating material of Claim 1 or 2.   The laminated body film in which the film | membrane of Claim 3 was provided in at least one part of the base film. A base film;
A seal part for bonding the base films in a state where the base films are in contact with each other;
Including
The said seal | sticker part is a bag body obtained by heating this film | membrane installation part in the state which the film | membrane installation parts provided with the film | membrane of Claim 3 contacted. Production of a film comprising a step of applying a heat-sealable coating material containing egg white protein, urea , polyhydric alcohol and an aqueous medium to a substrate to form a coating film, and a step of removing the aqueous medium from the coating film Method.

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