JP5038014B2 - Antibacterial mold sheet - Google Patents

Description

  The present invention relates to an antibacterial and antifungal sheet using allyl isothiocyanate.

  Allyl isothiocyanate, which is the main component of yam and pepper, is known to have an antibacterial and antifungal effect. Various antibacterial and antifungal materials such as films and sheets that contain this allyl isothiocyanate and can exhibit its antibacterial and antifungal effects by gradually releasing it have been studied.

  For example, Patent Document 1 discloses a polyurethane resin sheet in which allyl isothiocyanate is contained in a polyurethane resin composed of a polyfunctional isocyanate and a polyol.

  Further, Patent Document 2 discloses a volatile drug-releasing sheet-like material in which gas permeable layers are laminated on both surfaces of a kneaded material layer containing allyl isothiocyanate in rosin or rosin ester.

JP-A-9-151317 JP 2003-171208 A

  However, when allyl isothiocyanate is contained in a polyurethane resin as described in Patent Document 1, when a polyurethane resin using a low molecular weight isocyanate is used, the viscosity is greatly reduced by mixing with allyl isothiocyanate. have done. When coating the film with the mixture in such a low viscosity state, for example, a method such as gravure coating can be used, but the viscosity is too low to ensure the necessary coating amount. When laminating between films and winding up, problems such as winding slippage or leakage of the mixture from the laminated cross section until the viscosity of the mixture rises occurred.

  In addition, in order to maintain allyl isothiocyanate necessary to fully exert the effect when reducing the allyl isothiocyanate content in the mixture and coating it in a highly viscous state, a large amount of urethane is required. Since resin is required, it has become expensive.

  Furthermore, when a sheet of only one resin sheet in which allyl isothiocyanate is contained in a polyurethane resin is used, allyl isothiocyanate is continuously released even at low temperatures, so that it has an antibacterial and antifungal effect that is refrigerated and stored frozen. Even in situations where allyl isothiocyanate does not have to be realized. For this reason, even if the product is heated in a microwave oven or the like after refrigeration and frozen storage and attempts to exert the antibacterial and antifungal effect in the situation after the heating, allyl isothiocyanate has already been exhausted and the antibacterial When the mold effect has to be exhibited, the required effect may not be achieved.

  On the other hand, those using rosin as described in Patent Document 2, because rosin is easily melted by heat, when used as a cover sheet for tableware, when heated with a food in a microwave oven, the rosin melts. There was a problem that the resin leaked from the sheet cross section and adhered to food.

  Accordingly, the present invention is an antibacterial and antifungal sheet that releases allyl isothiocyanate over a long period of time, and does not melt even when heated by a microwave oven or the like in foods. An object is to obtain an antibacterial and antifungal sheet capable of exhibiting an antibacterial and antifungal effect by suppressing a released amount and releasing a sufficient amount of allyl isothiocyanate after heating at high production efficiency.

  In this invention, allyl isothiocyanate and a urethane resin using an isocyanate-based urethane prepolymer having a number average molecular weight of 500 or more and 10,000 or less are mixed, and the viscosity is at any temperature of 40 ° C. to 60 ° C. An antibacterial and antifungal agent layer made of an antibacterial and antifungal mixture capable of taking a value of 600 mPa · s or more and 2500 mPa · s or less is sandwiched between other layers, and at least one other layer is a polyethylene terephthalate film. The antibacterial and antifungal sheet used as an allyl isothiocyanate adsorbing film solves the above problems.

  In an isocyanate-based urethane prepolymer having a molecular weight of less than 500, mixing with allyl isothiocyanate decreases the viscosity too much, but mixing an isocyanate-based urethane prepolymer with an allyl isothiocyanate having a molecular weight in the above range. In the temperature range in which allyl isothiocyanate is less likely to volatilize, the viscosity can be easily applied on the sheet, and by applying this mixture on the film, it is inexpensive. It is possible to efficiently form an antibacterial and antifungal layer.

  Further, at least one other layer of the laminated sheet including the antibacterial / antifungal layer is an allyl isothiocyanate adsorbing film, and allyl isothiocyanate released from the antibacterial / antifungal agent layer is allyl isothiocyanate when stored at room temperature or lower. It was made to adsorb | suck to an adsorptive film, and discharge | release was suppressed, and the adsorbed allyl isothiocyanate was able to be discharge | released at the time of a heating. Thereby, when allyl isothiocyanate is unnecessary, useless release can be suppressed, and allyl isothiocyanate can be released at a timing that requires an antibacterial and antifungal effect.

  Since the antibacterial and antifungal sheet according to the present invention has a suitable viscosity when mixing allyl isothiocyanate and urethane prepolymer, the antibacterial layer containing allyl isothiocyanate is easily applied to the sheet and is easy to manufacture. Moreover, since the resin to be mixed is a urethane resin cured by reaction, it does not cause thermal melting under the heating conditions for normal food processing, and can retain the function as an antibacterial and antifungal sheet. For this reason, the antibacterial and antifungal sheet according to the present invention is usually refrigerated and frozen and used for packaging materials and packaging of refrigerated and frozen foods that are heated in a microwave oven before eating. The release of thiocyanate can be suppressed, and the antibacterial and antifungal effect of allylisothiocyanate can be exhibited at the time when the antibacterial and antifungal effect after heating is required.

The present invention will be described in detail below.
The present invention is an antibacterial / antifungal sheet in which at least one layer other than the surface layer of the laminated sheet composed of three or more layers is an antibacterial / antifungal agent layer and the other at least one layer is an allyl isothiocyanate adsorbing film. is there. Here, the surface layer refers to two layers constituting the surface of the laminated sheet. That is, the antibacterial and antifungal agent layer is not exposed on the surface and is sandwiched between other layers.

  The antibacterial and antifungal agent layer is composed of an antibacterial and antifungal mixture of allyl isothiocyanate and a urethane resin. By mixing with the urethane resin, allyl isothiocyanate is fixed, and allyl isothiocyanate having an antibacterial and antifungal effect is released over time.

  The urethane resin is made of an isocyanate-based urethane prepolymer, and is a one-component urethane polymer that is cured by contact with moisture in the air, or a two-component urethane polymer obtained by mixing an isocyanate-based urethane prepolymer and a polyol. Either.

  The isocyanate-based urethane prepolymer is a polymer obtained by urethane polymerization using a diisocyanate or polyisocyanate having two or more isocyanate groups, and includes an aromatic diisocyanate and an aliphatic diisocyanate.

  Specific examples of the aromatic diisocyanate include 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, or 2,2′-diphenylmethane diisocyanate, or a mixture thereof (MDI), m-phenylene diisocyanate. Or p-phenylene diisocyanate, or a mixture thereof, 4,4′-diphenyl diisocyanate (NDI), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, or a mixture thereof (TDI). . Examples of the aliphatic diisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate, 1,2-, 2,3-, or 1,3-butylene diisocyanate, 2,4,4. -Or 2,2,4-trimethylhexamethylene diisocyanate and the like.

  Among these, an aromatic urethane prepolymer having an aromatic ring is more preferable because the mixture is easily cured even when the mixing ratio of allyl isothiocyanate is high. On the other hand, when the aliphatic isocyanate urethane prepolymer is used, the mixture may not be cured when the mixing ratio of allyl isothiocyanate is high.

  The number average molecular weight of the isocyanate-based urethane prepolymer needs to be 500 or more, and preferably 10,000 or less. When it is less than 500, when it is mixed with allyl isothiocyanate, the viscosity necessary for coating cannot be obtained, and coating cannot be performed. It is possible to react with moisture in the air or the hydroxyl group of the polyol component until the viscosity required for coating is reached, but it is difficult to keep the viscosity constant because of the progress of the reaction. Further, it is necessary to change the coating thickness or change the setting of the machine, and there is a possibility that a uniform sheet cannot be obtained. On the other hand, the number average molecular weight needs to be 10,000 or less, and is preferably 5,000 or less. If it exceeds 10,000, the viscosity is too high and mixing with allyl isothiocyanate may be difficult.

  Examples of the polyol include polyether-based polyols and polyester-based polyols, and these may be used alone or in combination.

  The polyether-based polyol is a polymer having a plurality of hydroxyl groups in a molecule and connected by an ether bond. Examples of the polyether polyol include homopolymers such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, and 3-methyltetrahydrofuran, and copolymers.

  The polyester polyol can be obtained by a condensation reaction between a polybasic acid and a polyhydric alcohol or a transesterification reaction between an alkyl ester of a polybasic acid and a polyhydric alcohol. Examples of the polybasic acid or alkyl ester thereof include dimer acid, orthophthalic acid, isophthalic acid, phthalic acid such as terephthalic acid, dialkyl esters thereof, or mixtures thereof. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,7-heptanediol, and the like.

  The above-mentioned isocyanate-based urethane prepolymer tends to react more quickly with aromatics than aliphatic, and the above-mentioned polyols tend to react faster with polyesters than with polyethers. Therefore, in order to suppress the viscosity increase during coating without delaying curing, the aromatic isocyanate urethane prepolymer is combined with the polyether polyol, and the aliphatic isocyanate urethane prepolymer is combined with the polyester polyol. preferable.

  The number average molecular weight of the polyol is preferably 500 or more, and more preferably 1000 or more. When it is less than 500, when the isocyanate-based urethane prepolymer and allyl isothiocyanate are mixed, the viscosity necessary for coating cannot be obtained and coating may not be possible. In addition, it is possible to wait until the viscosity required for coating by reacting with the hydroxyl group contained in the polyol, but it is difficult to keep the viscosity constant because the reaction has progressed. There is a possibility that a uniform sheet cannot be obtained due to a change in thickness or a change in machine settings. On the other hand, the number average molecular weight is preferably 10,000 or less, and more preferably 5,000 or less. When it exceeds 10,000, it may be difficult to uniformly mix and react with the mixture of the isocyanate-based urethane prepolymer and allyl isothiocyanate.

  In order to obtain the two-pack type urethane polymer, for example, the isocyanate-based urethane prepolymer and the polyol are stored separately, and after one of the higher viscosity and allyl isothiocyanate are uniformly mixed, The method of mixing the other is mentioned. In addition, at this time, any additive used for general urethane resin is added within the range that does not inhibit the antibacterial and antifungal effect of the antibacterial and antifungal sheet according to the present invention and the viscosity is kept within the required range. May be. Furthermore, as an additive used for applications other than viscosity adjustment, a stabilizer for stabilizing allyl isothiocyanate may be added, and an antioxidant, a light stabilizer, and cyclohexane for stabilizing by inclusion of allyl isothiocyanate. Dextrin and the like.

  When this allyl isothiocyanate, the above-mentioned isocyanate-based urethane prepolymer, and the above-mentioned polyether-based polyol or the above-mentioned polyester-based polyol are mixed to obtain an antibacterial and antifungal mixture, a sealed space is used so that allyl isothiocyanate does not volatilize. It is preferable to carry out with. Also, in order to obtain a uniform mixture, the above-mentioned isocyanate-based urethane prepolymer, the above-mentioned polyether-based polyol or the above-mentioned polyester-based polyol is heated and mixed with allyl isothiocyanate in a low viscosity state, which is optimal for coating. It may be cooled to a suitable temperature.

  In order to obtain the one-pack type urethane polymer, for example, the isocyanate-based urethane prepolymer and allyl isothiocyanate are stored in separate sealed containers, mixed in the line using a line mixer, and then coated. Then, before laminating the film, there is a method of giving moisture and reacting, and after mixing the above isocyanate-based urethane prepolymer and allyl isothiocyanate uniformly in a sealed container, giving moisture and reacting in the same way. It is done. In addition, at this time, in the range that does not inhibit the antibacterial and antifungal effect of the antibacterial and antifungal sheet according to the present invention, and in the range that keeps the viscosity within the required range, add any additive used for general urethane resin May be.

  In either case of the one-component urethane polymer and the two-component urethane polymer, the viscosity of the antibacterial and antifungal mixture obtained is higher as the temperature is lower. Coating under conditions requires variation in coating thickness, change in machine settings, and the like, and there is a risk that a uniform sheet cannot be obtained. Therefore, the coating temperature is preferably 40 ° C. or higher. On the other hand, when the coating temperature exceeds 60 ° C., the evaporation amount of allyl isothiocyanate cannot be ignored, so the coating temperature needs to be 60 ° C. or less. The antibacterial and antifungal mixture needs to have a viscosity that can be applied at any temperature within the temperature range of 40 ° C. to 60 ° C.

  The viscosity that can be applied is required to be 600 mPa · s or more. This is because when the viscosity is less than 600 mPa · s, the viscosity is too low to easily flow and coating cannot be performed. Therefore, when the viscosity is too low to be applied, the coating is performed after the temperature is lowered to at least 600 mPa · s by lowering the temperature within the above temperature range. Even if it cools to 40 degreeC, it cannot be used for this invention as a viscosity is less than 600 mPa * s. On the other hand, it is necessary to be 2500 mPa · s or less. On the other hand, if it exceeds 2500 mPa · s, the viscosity is too high and thin coating cannot be performed, coating unevenness may occur, or coating may not be possible. Therefore, when the viscosity is too high to be applied, the temperature is set within the above range, and the coating is performed after the maximum is 2500 mPa · s or less. If the viscosity exceeds 2500 mPa · s even when heated to 60 ° C., it cannot be used in the present invention.

  The weight mixing ratio of these allyl isothiocyanate and urethane resin is preferably 5:95 to 35:65 in any of the one-component urethane polymer and the two-component urethane polymer. : More preferably, it is 90-30: 70. If the amount of allyl isothiocyanate is less than 5:95, the resulting antibacterial and antifungal sheet can exhibit the antibacterial and antifungal effect, which is insufficient in duration and release, resulting in an insufficient effect. On the other hand, when the urethane resin is less than 35:65, the viscosity of the antibacterial and antifungal mixture is extremely lowered, and it cannot be kept in the above-mentioned coatable range, or allyl isothiocyanate is fixed. The antibacterial and antifungal agent layer cannot be formed. Furthermore, the weight mixing ratio when the aliphatic isocyanate-based urethane prepolymer is used is preferably 5:95 to 15:85.

  Next, the allyl isothiocyanate adsorptive film serving as at least one other layer of the laminated sheet will be described. The allyl isothiocyanate adsorbing film is an allyl isothiocyanate adsorbing film capable of adsorbing allyl isothiocyanate and releasing allyl isothiocyanate adsorbed during heating. That is, when the laminated sheet is composed of three layers, at least one of the sheets sandwiching the antibacterial and antifungal agent layer is an allyl isothiocyanate adsorbing film. When the laminated sheet is composed of four or more layers, the antibacterial and antifungal agent layer is in direct contact with the allyl isothiocyanate adsorbing film and when there is another layer between the allyl isothiocyanate adsorbing film. However, direct contact is preferred because it tends to adsorb allylisothiocyanate released from the antibacterial and antifungal agent layer.

  When the allyl isothiocyanate adsorbing film is provided as at least one layer of a laminated sheet, the antibacterial and antifungal sheet is allyl isothiocyanate in an environment of 10 ° C. or lower for refrigerated storage or an environment of −18 ° C. or lower for frozen storage. Can be suppressed. For this reason, allyl isothiocyanate is prevented from being unnecessarily released from the antibacterial and antifungal sheet according to the present invention at the time of refrigeration and frozen storage where the bacteria are hardly active due to the low temperature and the antibacterial and antifungal effect is unnecessary. On the other hand, the allyl isothiocyanate adsorbing film can release the adsorbed allyl isothiocyanate during heating.

  When the antibacterial and antifungal effect is required, the antibacterial and antifungal sheet is heated to release allyl isothiocyanate adsorbed by the allyl isothiocyanate adsorbing film. The allyl isothiocyanate released is not released as it is from the allyl isothiocyanate adsorbing film side, but is often released from the surface layer on the opposite side once through the antibacterial and antifungal layer. . This is because the concentration of adsorbed allyl isothiocyanate is not uniform throughout the film, but the portion closer to the antibacterial and antifungal layer is higher in concentration and even if heated, the allyl isothiocyanate This is because the adsorptive film hardly transmits allyl isothiocyanate. That is, allyl isothiocyanate concentrated on the side close to the antibacterial / antifungal agent layer is more likely to return to the antibacterial / antifungal agent layer rather than permeating the entire film, and the amount released from the opposite side However, it becomes larger than the release amount from the surface on the side of the allyl isothiocyanate adsorbing film.

  In addition, the released allyl isothiocyanate is not released all at once when heated, but is released to some extent during heating, but it is released slowly while cooling in a room temperature environment after heating. to continue. As described above, this is not directly released from the allyl isothiocyanate-adsorbing film, but is once released from the opposite surface via the antibacterial and antifungal agent layer. This is because.

  With such an allyl isothiocyanate adsorbing film on the surface, when the antibacterial and antifungal sheet according to the present invention is attached to foods, allyl isothiocyanate is hardly released during refrigerated storage, and the antibacterial and antifungal effect after heating Allyl isothiocyanate can be released when required.

Specifically, the allyl isothiocyanate adsorbing film has an allyl isothiocyanate maximum adsorption amount of 30 mg / m ² or more and 3000 mg / m ² or less in an environment of 30 ° C. It is preferable that the amount of permeation is 5 g / m ² or less at 30 ° C. When these antibacterial and antifungal sheets are used for foods that are refrigerated and frozen, the amount of allyl isothiocyanate that is wasted in a normal storage environment can be sufficiently suppressed. At this temperature, the activity of most fungi and fungi is suppressed, so that the growth of fungi and the spread of fungi can be suppressed without releasing allyl isothiocyanate. Since such a storage period is long, if allyl isothiocyanate is released in vain, it cannot be released when the antibacterial and antifungal effect is necessary. By adsorbing allyl isothiocyanate released from the fungicide layer, wasteful consumption of allyl isothiocyanate can be suppressed.

In addition, the measuring method of said maximum adsorption amount prescribed | regulated here is based on the following method.
In a glass desiccator, add allyl isothiocyanate necessary for the allyl isothiocyanate to reach the saturated vapor pressure with respect to its volume, and place 100 cm ² of each film in the desiccator so as not to contact with allyl isothiocyanate. To do. After this glass desiccator is left at 30 ° C. for 7 days, each film is taken out and allyl isothiocyanate condensed on the film surface is wiped off with a tissue paper. Thereafter, each film was further left at 30 ° C. for 1 hour to volatilize the excessively attached allyl isothiocyanate, and then each film was recovered. The amount remaining in the film using dichloromethane as an extraction solvent was determined by gas chromatography. And the value is determined as the maximum amount adsorbed on the film to be measured.

Moreover, the measurement method of said permeation | transmission amount prescribed | regulated here is based on the following method.
Add 1 g of allyl isothiocyanate to a stainless steel moisture permeable cup (cylindrical), place the film to be measured on the opening, and place and fix a ring with an opening having the same area and shape as the opening, Seal. The weight of the moisture permeable cup was measured over time, and the reduced weight was defined as the permeated amount of allyl isothiocyanate per area of the opening.

  On the other hand, the allyl isothiocyanate adsorbing film needs to be able to release the adsorbed allyl isothiocyanate by heating. Specifically, in the heating environment of 60 ° C. or more, the adsorbed allyl isothiocyanate 40 % Or more can be released. This temperature is the temperature when the food to be refrigerated or frozen is warmed with a microwave oven or the like. Thereby, by releasing and permeating allyl isothiocyanate, the gas of allyl isothiocyanate can be supplied around the food, and the antibacterial and antifungal effect can be exerted to protect the food.

  As the polyethylene terephthalate film as the allyl isothiocyanate adsorbing film, for example, biaxially stretched polyethylene terephthalate, amorphous polyethylene terephthalate, glycol-modified copolymer polyethylene terephthalate, or the like can be used. Polyethylene terephthalate film has the property of adsorbing allyl isothiocyanate at room temperature, but when heated, the film structure relaxes and allyl isothiocyanate adsorbed so far can be released.

When a polyethylene terephthalate film is used as the allyl isothiocyanate adsorbing film, the thickness of the film is preferably 7 μm or more. If it is less than 7 μm, not only wrinkles are likely to occur during processing, but also the amount of adsorption becomes insufficient, so that sufficient antibacterial and antifungal effects may not be obtained when necessary. On the other hand, it is preferable in it being 50 micrometers or less. If it exceeds 50 μm, it becomes very expensive and may not be used in terms of cost. Specifically, in a polyethylene terephthalate film having a thickness of 25 μm, the maximum adsorption amount is about 400 mg / m ² . Moreover, when using the film made from a polyethylene terephthalate on both surfaces, the one side is more preferable in order to permeate | transmit allyl isothiocyanate, It is preferable in it being 7 micrometers or more and 12 micrometers or less.

  In addition, the sheet that forms two layers on both sides of the antibacterial and antifungal agent layer is an allyl isothiocyanate permeable film in which at least one of them can sufficiently permeate allyl isothiocyanate, and ensures the permeation amount of allyl isothiocyanate. What can be adjusted according to the use of the antibacterial and antifungal sheet according to the present invention is preferable.

  In particular, the antibacterial and antifungal agent layer is more preferably sandwiched between the allyl isothiocyanate adsorbing film and the allyl isothiocyanate permeable film. When the allyl isothiocyanate adsorbing film is directly laminated on the antibacterial and antifungal agent layer, allyl isothiocyanate is gradually adsorbed, and the adsorbed allyl isothiocyanate is hardly released. On the other hand, since the allyl isothiocyanate permeable film repeats adsorption and release, as a result, most of the allyl isothiocyanate released from the antibacterial and antifungal agent layer results in the allyl isothiocyanate adsorbing film. When adsorbed, the adsorption amount becomes larger than that of the allyl isothiocyanate permeable film. For this reason, more than half of allyl isothiocyanate possessed by the antibacterial and antifungal agent layer can be adsorbed, and wasteful reduction of allyl isothiocyanate can be suppressed.

  In addition, the allyl isothiocyanate permeable film may be provided on both sides of the antibacterial and antifungal agent layer. In that case, the allyl isothiocyanate adsorbing film is laminated outside at least one of the layers. Will be. In this case, since the allyl isothiocyanate adsorbing film adsorbs only the allyl isothiocyanate released from both sides of the antibacterial and antifungal layer almost permeated through the allyl isothiocyanate permeable film, The amount adsorbed by the allyl isothiocyanate adsorbing film is reduced.

Specifically, the permeation amount of allyl isothiocyanate per day in the allyl isothiocyanate permeable film is preferably 10 g / m ² or more and 200 g / m ² or less at 30 ° C. If it is less than 10 g / m ² , the amount of permeation is too small and the antibacterial and antifungal effect may not be sufficiently exhibited. On the other hand, if it exceeds 200 g / m ² , the amount of permeation is too large and the duration is too short.

As the allyl isothiocyanate permeable film, a polyolefin film or a cellophane film can be used. Examples of the polyolefin film include a polypropylene film such as a biaxially stretched polypropylene film and an unstretched polypropylene film, and a polyethylene film. Among these, a polypropylene film is preferable, and a biaxially stretched polypropylene film is more preferable. The thickness of the allyl isothiocyanate permeable film is not particularly limited, but is preferably 9 μm or more and 80 μm or less, and more preferably 12 μm or more and 60 μm or less. If it is less than 9 μm, it is too thin and may cause a problem in strength. On the other hand, if it exceeds 80 μm, the antibacterial and antifungal sheet may be easily curled or the permeability may be insufficient. In addition, since these allyl isothiocyanate permeable films are provided to allow permeation of allyl isothiocyanate, the smaller the maximum adsorption amount of allyl isothiocyanate, the more preferable. Specifically, the maximum adsorption amount of allyl isothiocyanate is 30 Under the condition of ° C., it is 200 mg / m ² or less. As such a sheet, for example, cellophane having a thickness of 24 μm is about 50 mg / m ² .

  As a method of sandwiching the antibacterial and antifungal agent layer between the allyl isothiocyanate adsorbent film or the allyl isothiocyanate permeable film, the antibacterial and antifungal mixture is applied to one of these films, A method of adhering another film on the formed antibacterial and antifungal layer is mentioned. In addition, as a method of coating the antibacterial and antifungal mixture on the film, the antibacterial and antifungal mixture is adjusted according to the gap between the rolls and the number of rotations, and the transfer is repeated. Examples thereof include a coating method, a method of adjusting the coating amount by providing a certain gap, and a transfer coating method. Examples of the coating apparatus include a non-solvent laminator, a reverse coater, and a lip coater.

  When the antibacterial / antifungal mixture is applied onto the film to form the antibacterial / antifungal agent layer, it is preferable to perform aging for several days at room temperature or in a heated state in order to cure the urethane resin. . When the antibacterial and antifungal agent layer is applied directly or via an allyl isothiocyanate permeable film onto an allyl isothiocyanate adsorbing film, allyl isothiocyanate adsorbs to the allyl isothiocyanate adsorbing film during the aging period. Is done.

The application amount of the antibacterial and antifungal layer containing the urethane resin is preferably 0.5 g / m ² or more, and more preferably 1 g / m ² or more. If the amount is less than 0.5 g / m ² , the amount of the antibacterial / antifungal agent is too small, and the effect of the obtained antibacterial / antifungal sheet may be insufficient. On the other hand, it is preferably 3 g / m ² or less, and more preferably ² g / m ² or less. If it exceeds 3 g / m ² , there is a high possibility that the layers on both sides in contact with the antibacterial and antifungal agent layer will cause winding deviation, and may cause wrinkles.

  In addition, after coating the antibacterial and antifungal agent layer on the allyl isothiocyanate adsorbing film, by laminating the allyl isothiocyanate permeable film on the opposite surface of the antibacterial and antifungal agent layer, An antibacterial and antifungal agent layer can be sandwiched between the allyl isothiocyanate adsorbing film and the allyl isothiocyanate permeable film. Conversely, after the antibacterial and antifungal agent layer is coated on the allyl isothiocyanate permeable film, the allyl isothiocyanate adsorbing film may be laminated on the opposite surface.

  It is also possible to laminate the allyl isothiocyanate permeable film on one surface of the antibacterial and antifungal agent layer, and further to make both surface layers the allyl isothiocyanate adsorbing film. When the allyl isothiocyanate adsorbing film is used, almost allyl isothiocyanate cannot be released even when heated. Therefore, at least one of the surface layers is the allyl isothiocyanate permeable film, and it is preferable that the film is directly laminated on the antibacterial and antifungal agent layer.

Further, the release amount of allyl isothiocyanate per unit area and time required for the antibacterial and antifungal sheet according to the present invention to continue to exhibit the antibacterial and antifungal effect by the release of allyl isothiocyanate is 3 mg / m ² · hour or more is preferable. This is because if it is less than 3 mg / m ² · hour, the antibacterial properties exhibited may be insufficient. On the other hand, the release amount is preferably 1000 mg / m ² · hour or less. This is because if it exceeds 1000 mg / m ² · hour, odors may adhere to the food or the taste may be affected. The duration and the release amount can be adjusted by the coating amount of the antibacterial and antifungal layer, the blending ratio of the allyl isothiocyanate, the permeability of the allyl isothiocyanate permeable film, and the like.

  As a specific method of using the antibacterial / antifungal sheet according to the present invention, for example, a method for exerting an antibacterial / antifungal effect, a freshness-keeping effect, etc. on the food by using it for packaging covering the upper surface or the entire food. . Since the antibacterial / antifungal sheet according to the present invention uses the urethane resin, the antibacterial / antifungal agent layer can be maintained without being melted by heat under the conditions of heating food in a microwave oven or the like. Alternatively, the antibacterial and antifungal effect can be maintained for the food to be packaged by continuously releasing allyl isothiocyanate in a necessary direction on both sides for a certain period of time.

  In addition, since at least one surface is the allyl isothiocyanate adsorbing film, it can be stored without releasing almost allyl isothiocyanate at room temperature, refrigerated or frozen. In other words, when the above antibacterial and antifungal sheet is used for food packaging or when it is placed in the food packaging, allyl isothiocyanate adsorbed on the allyl isothiocyanate permeable film is released until the temperature of the food decreases, and the antimicrobial In a situation where the fungus-proofing effect is exhibited and the bacteria are difficult to propagate as in refrigeration and freezing, allyl isothiocyanate can be stored without waste. And when food is heated in a microwave oven etc. and there is time to eat, it will be at a temperature at which bacteria can propagate until then, but at that stage a sufficient amount of antibacterial and antifungal sheet is used. By releasing allyl isothiocyanate, it is possible to suppress the growth of bacteria and maintain a sanitary environment.

  In addition, when using for such a packaging, it is preferable to use so that the layer of the said allyl isothiocyanate adsorbent film may be located outside the said antibacterial and antifungal agent layer. This is because there is little allyl isothiocyanate that permeates the allyl isothiocyanate adsorbing film, and most is released from the opposite surface.

  Further, the antibacterial / antifungal sheet according to the present invention can be deformed by vacuum forming in which the antibacterial / antifungal sheet is once heated to be easily deformable and then vacuum sucked into a concave mold, or once heated. What was shaped into the food container by carrying out the thermoforming which shape | molds while heating with a heated concave mold and a convex mold from temperature is mentioned. For example, the antibacterial and antifungal sheet cut into a circle as shown in FIG. 1 (a) is made into a cup shape as shown in FIG. 1 (b) or a rectangle as shown in FIG. 2 (a). In addition, the antibacterial and antifungal sheet formed into a tray shape as shown in FIG. In particular, when the sheet is cut into a rectangle as shown in FIG. 2 and molded, the sheet obtained by lamination can be used without waste.

Hereinafter, the present invention will be described more specifically with reference to examples. First, the film, urethane resin, and allyl isothiocyanate used will be described.
PET # 25: Toyobo Co., Ltd .: Polyethylene terephthalate film (allyl isothiocyanate adsorbing film), thickness 25 μm
・ OPP # 20: manufactured by Toyobo Co., Ltd .: biaxially stretched polypropylene film (allyl isothiocyanate permeable film), thickness 20 μm

First aromatic isocyanate urethane prepolymer: Takei Mitsui Chemicals, Inc .: Takenate A-242A Number average molecular weight (Mn): 1268 (two-component urethane prepolymer)
・ High molecular weight polyether polyol: made by Mitsui Takeda Chemical Co., Ltd .: Takelac XA-244B Number average molecular weight (Mn): 3254
・ Second aromatic isocyanate-based urethane prepolymer: Takei Mitsui Chemicals, Inc .: Takenate A-260 Number average molecular weight (Mn): 2129 (one-component urethane prepolymer)
・ Allyl isothiocyanate …… Nippon Terpene Co., Ltd.

The number average molecular weight was measured using a gel permeation chromatograph (GPC) under the following conditions.
-Equipment: HLC-8120GPC manufactured by Tosoh Corporation
-Column: TSK-GEL α-M manufactured by Tosoh Corporation
-Mobile phase: 0.5 mol / l NaNO ₃ in DMSO
・ Detector: Differential refractometer (RI)
・ Flow rate: 1 ml / min
-Column temperature: 40 ° C
-Number average molecular weight (Mn): Polyethylene glycol (PEG) conversion

[Production and release test of antibacterial / antifungal sheet]
Example 1
A first aromatic isocyanate urethane prepolymer, a high molecular weight polyether polyol and allyl isothiocyanate are mixed at a weight mixing ratio of 75:10:15, and an antibacterial and antifungal mixture having a viscosity at 40 ° C. of 1040 mPa · s is obtained. Produced. At that time, a B-type viscometer manufactured by Tokimec Co., Ltd. was used for viscosity measurement. This antibacterial / antifungal mixture was coated on PET # 25 with a non-solvent laminator by Fuji Machine Industry Co., Ltd. so that the coating amount was 1.8 g / m ² to form an antibacterial / antifungal agent layer. It was. OPP # 20 was bonded to the surface of the antibacterial / antifungal agent layer opposite to PET # 25 to obtain an antibacterial / antifungal sheet having three layers and the surface layer being an allyl isothiocyanate permeable film.

<Room temperature storage test>
100 pieces of the obtained antibacterial and antifungal sheet were sealed in an aluminum bag, and the test specimen stored for one month in a 40 ° C. incubator was cut into 10 cm × 16 cm square, 30 ° C., 25% RH, no wind condition The content of allyl isothiocyanate in the sheet after 1 hour, 3 hours, 6 hours and 24 hours was measured with a gas chromatograph HP 6890 manufactured by HEWLETT PACKARD, and the content at the start of volatilization was measured. Each content was converted into a residual rate with a residual rate of 100%. The results are shown in Table 1.

<Frozen storage test>
The test specimen was left in a freezer at −18 ° C., and the remaining amount of allyl isothiocyanate after 7, 14, 30, 60 days was measured and similarly converted into a residual rate. The results are shown in Table 2.

<Heat resistance test>
The antibacterial and antifungal sheet thus obtained was heated in a microwave oven with a rated output of 500 W (manufactured by Sharp Corporation: RE-M20) for 1 minute to observe changes in appearance, and the surface film was pulled in a 180 ° direction to peel off. A test was conducted. As a result, no change in appearance was observed, and in the peel test, the urethane film was not dissolved and the film on the surface layer was only broken.

<Release test after heating>
The test specimen was placed in the microwave oven together with a cup containing 50 cc of water and heated for 2 minutes, and then the test specimen was left under windless conditions of 30 ° C. and 25% RH, and allyl isothiocyanate over time. The content of was measured and converted to a residual rate with 100% of allyl isothiocyanate before heating. The results are shown in Table 3.

<Antimicrobial test after heating>
80 g of sterilized cooked rice was put into a similarly sterilized container (250 ml), and 20 μl of Escherichia coli solution was dropped onto 20 portions of the cooked rice surface. Immediately thereafter, the antibacterial and antifungal sheet was cut into a 60 mm × 100 mm square, placed on cooked rice, covered, and stored at 30 ° C. for 6 hours. After 6 hours, the whole amount of cooked rice 80 g was recovered, and the number of E. coli in the cooked rice was measured. Moreover, it measured also about the case where an antimicrobial mold sheet is not placed as a comparative control. The results are shown in Table 4. In addition, the unit in a table | surface is (CFU / 80g cooked rice).

(Comparative Example 1)
The same measurement was performed using OPP # 20 instead of PET # 25 of Example 1. The results are shown in Tables 1-4. Further, when the heating test was carried out in the same manner as in Example 1, no change in appearance was observed, and in the peeling test, the surface layer film was only broken without dissolving the urethane resin.

(Example 2)
The second aromatic isocyanate urethane prepolymer and allyl isothiocyanate were mixed at a weight mixing ratio of 80:20 to prepare an antibacterial and antifungal mixture having a viscosity at 40 ° C. of 1290 mPa · s. This antibacterial and antifungal mixture was applied onto PET # 25 at 40 ° C. so that the coating amount was 1.8 g / m ² to form an antibacterial and antifungal agent layer. The surface of the antibacterial / antifungal agent layer is bonded to OPP # 20 on the opposite side of the PET # 25 and left at 40 ° C. for 2 days to cure the antibacterial / antifungal layer and consists of three layers. Obtained an antibacterial and antifungal sheet comprising an allyl isothiocyanate permeable film and a polyethylene terephthalate film which is an allyl isothiocyanate adsorbing film. The same measurement as in Example 1 was performed on this sheet. The results are shown in Tables 1-4.

(Example 3)
Using the antibacterial and antifungal sheet of Example 1 which is a rectangular shape of 70 mm in length and 100 mm in width, a continuous vacuum forming machine (made by Teradakikai), a container having the shape of FIG. Of the tests prepared and conducted in Example 1, a release test after heating and an antibacterial test were performed. The results are shown in Tables 3 and 4.

(result)
In the room temperature storage test, the sheets of Examples 1 and 2 were maintained at around 80% even after 24 hours at 30 ° C., regardless of the type of urethane prepolymer. Released all allyl isothiocyanate in 24 hours (Table 1).

  In the freezing storage test, the release rate is significantly lower than the environment at 30 ° C., but the allyl isothiocyanate is released in 30 days in the sheet of Comparative Example 1, whereas the sheets of Examples 1 and 2 Then, 70% or more of allyl isothiocyanate is retained at 30 days, and even after 30 days, almost the same amount of allyl isothiocyanate is retained (Table 2). This is considered that most of allyl isothiocyanate released from the antibacterial and antifungal agent layer is adsorbed and fixed to PET # 25.

  In the release test after heating, the sheet of Comparative Example 1 released most of the allyl isothiocyanate immediately after heating, but the sheets of Examples 1 and 2 released over 24 hours later than immediately after heating. The amount was greater and it was found that allyl isothiocyanate was released slowly from PET # 25 after heating. Further, in Example 3 in which the sheet of Example 1 was vacuum-formed, allyl isothiocyanate could be gradually released in the same manner as in Example 1.

  In the antibacterial test, the antibacterial effect was not seen at all in Comparative Example 1, and the bacteria propagated. In Examples 1 to 3, the number of bacteria was hardly changed even after 6 hours, and the reproduction could be suppressed.

(A) Conceptual diagram of sheet cut out in a circle, (b) Perspective view of antibacterial and antifungal food cup molded from (a) (A) Conceptual diagram of sheet cut out in rectangle, (b) Perspective view of antibacterial and antifungal food cup molded from (a)

Claims (4)

One layer other than the surface layer of the laminated sheet composed of three or more layers is a urethane resin composed of an isocyanate-based urethane prepolymer having a number average molecular weight of 500 or more and 10,000 or less, and allyl isothiocyanate. It is made of an antibacterial and antifungal mixture that is mixed at a weight mixing ratio of 65:35 and has a viscosity of 600 mPa · s or more and 2500 mPa · s or less at any temperature from 40 ° C. to 60 ° C. An antibacterial and antifungal layer,
Other at least one layer, at 30 ° C. environment, the maximum adsorption amount of the allyl isothiocyanate 30 mg / ^{m 2} or more and 3000 mg / ^{m 2} or less, and in the 60 ° C. or more heating environment, adsorbed allyl isothiocyanate Do polyethylene terephthalate film is allyl isothiocyanate adsorbed film can emit 40% or more of Ri,
One of the surface layers consists of a polyolefin-based film or a cellophane film, which is an allyl isothiocyanate permeable film having a permeation amount of allyl isothiocyanate per day at 30 ° C. of 1 g / m ² or more and 200 g / m ² or less. ,
The antibacterial / antifungal sheet is sandwiched between the allyl isothiocyanate permeable film and the allyl isothiocyanate adsorbing film . One layer other than the surface layer of the laminated sheet composed of three or more layers is an isocyanate-based urethane prepolymer having a number average molecular weight of 500 or more and 10,000 or less, and a polyether having a number average molecular weight of 500 or more and 10,000 or less. A urethane resin composed of a polyol that is a polyol based on polyester, a polyester polyol, or both, and allyl isothiocyanate are mixed at a weight mixing ratio of 95: 5 to 65:35, and at any temperature between 40 ° C. and 60 ° C. , An antibacterial and antifungal agent layer comprising an antibacterial and antifungal mixture capable of having a viscosity of not less than 600 mPa · s and not more than 2500 mPa · s,
Other at least one layer, at 30 ° C. environment, the maximum adsorption amount of the allyl isothiocyanate 30 mg / ^{m 2} or more and 3000 mg / ^{m 2} or less, and in the 60 ° C. or more heating environment, adsorbed allyl isothiocyanate Do polyethylene terephthalate film is allyl isothiocyanate adsorbed film can emit 40% or more of Ri,
One of the surface layers consists of a polyolefin-based film or a cellophane film, which is an allyl isothiocyanate permeable film having a permeation amount of allyl isothiocyanate per day at 30 ° C. of 1 g / m ² or more and 200 g / m ² or less. ,
The antibacterial / antifungal sheet is sandwiched between the allyl isothiocyanate permeable film and the allyl isothiocyanate adsorbing film . Antibacterial and antifungal food cup was molded by using the antibacterial Kabishito according to claim 1 or 2. The antibacterial / antifungal sheet according to claim 1 or 2 or the antibacterial / antifungal food cup according to claim 3 and the allylisothiocyanate released from the antibacterial / antifungal agent layer during storage is stored in the allylisothiocyanate during storage. Adsorbed on an absorptive film,
By releasing the allyl isothiocyanate adsorbed from the allyl isothiocyanate adsorbing film at the time of heating or preheating the food, the food heated with the antibacterial / antifungal sheet or the antibacterial / antifungal food cup, the surrounding food, or An antibacterial and antifungal method for foods that exhibits antibacterial and antifungal effects against both.

Images