JP6524828B2 - Sterile paper and sterile packaging - Google Patents

Description

  The present invention relates to sterile paper and sterile packaging.

  Instruments used for surgery, treatment, etc. need to be sterilized before use, and such instruments are housed in a sterile package and sterilized. As a sterilization method carried out in a hospital etc., for example, after putting an object to be sterilized such as a scalpel and forceps in a sterilization package and sealing, sterilization is performed using gas sterilization method, high pressure steam sterilization method, radiation sterilization method and the like. The method is mentioned. In the gas sterilization method, the package is put in a pressure resistant container, the pressure in the container is reduced, the air inside the package is exhausted, and then the container is filled with ethylene oxide gas (EOG) or the like to fill the container with gas. Permeate and sterilize. In the high-pressure steam sterilization method, the package is exposed to high-temperature steam using an autoclave or the like, and repeated decompression and pressurization for sterilization. In the radiation sterilization method, radiation is used to sterilize. Among these, high-pressure steam sterilization and gas sterilization are often used in terms of cost and simplicity.

  Moreover, the instrument after sterilization is stored in the sterile package until it is used for surgery and the like, and is opened and used when used for surgery and treatment. Therefore, a sterile bag is a thin sheet such as two rectangular sheets or films on the front and back so that it is easy for the doctor or practitioner to use gloves in the hospital. ) Is manufactured using a peelable film or an easily tearable (tear openable) film, and upon opening, a peel open system for peeling two films and a tear system are adopted. It is common to

  As a technique regarding a sterilization package, the thing of patent documents 1-3 is mentioned, for example. Patent Document 1 is a technique relating to a package for easy-to-open sterilization obtained by thermally bonding the peripheries of both substrates using a synthetic resin film substrate as one packaging material and an air-permeable substrate as the other. . Patent Document 2 discloses a sterile package comprising a substrate made of paper, a peelable resin layer formed on one side of the substrate, and a heat-weldable resin layer formed on the peelable resin layer. Technology related to Patent Document 3 is a sterile bag paper in which a thermoplastic resin layer is provided on one side of a base paper, and the thermoplastic resin layer is characterized by being a mixture of two synthetic resin emulsions and / or dispersions. Things are disclosed.

Unexamined-Japanese-Patent No. 1-153471 gazette Unexamined-Japanese-Patent No. 5-254067 JP 2001-122348 A

  In the case of a peel-open type sterilization packaging in which the sterilization paper is peeled off from the sterilization packaging and opened, generation of paper dust due to substrate breakage at the time of peeling of the sterilization paper so that medical instruments and the like after sterilization are not recontaminated It is required to suppress On the other hand, it is also important to realize sterilization paper that can be applied to various sterilization methods such as gas sterilization using sterilization gas, high-pressure steam sterilization using steam, radiation sterilization using radiation and sterilization. . An object of the present invention is to realize sterile paper applicable to various sterilization methods while suppressing substrate destruction at the time of peeling.

The present invention has the following configuration.
[1] A paper substrate, and a heat adhesive layer laminated on one side of the paper substrate,
The heat adhesive layer comprises a particulate heat adhesive resin,
Sterilized paper with an Oken type air permeability of 700 seconds or less measured in accordance with JIS P 8121-2: 2012.
[2] The sterilized paper according to [1], wherein the glass transition point of the heat adhesive resin is 70 ° C. or more.
[3] The sterilized paper described in [1] or [2], wherein the heat adhesive layer contains a heat adhesive resin having a particle diameter of 3 μm or more.
[4] The heat-adhesive resin contains one or more selected from ethylene- (meth) acrylic acid copolymer, ethylene-vinyl acetate copolymer, acrylic acid ester polymer, polyethylene, and polybutene The sterilized paper as described in any one of [1]-[3].
[5] The sterilized paper according to any one of [1] to [4], wherein the paper base contains a polyacrylamide resin.
[6] The paper base material is manufactured using a pulp having a freeness of 250 mL or more and 700 mL or less measured according to JIS P 8121-2: 2012. Any of [1] to [5] Sterile paper as described in or.
[7] A sterile package obtained by thermocompression bonding the sterile paper according to any one of [1] to [6] and a packaging paper, a film or a container for sterilization.
[8] A peeling strength of 200 to 1500 gf / 15 mm at the time of peeling 180 degrees of the wrapping paper, the film or the sterilization container according to JIS P 8113: 2006 from the sterile packaging at a peeling speed of 300 m / min. The sterile package described in [7].

  ADVANTAGE OF THE INVENTION According to this invention, the sterilization paper which can be applied to various sterilization methods is realizable, suppressing base-material destruction at the time of peeling.

It is a sectional view showing typically sterilization paper concerning this embodiment. It is an electron micrograph of the heat-bonding layer of the sterilization paper which concerns on Example 1. FIG.

FIG. 1 is a cross-sectional view schematically showing a sterile paper 1 according to the present embodiment.
The sterile paper 1 according to the present embodiment includes a paper base 2 and a thermal adhesive layer 3 laminated on one side of the paper base 2. The heat adhesive layer 3 contains a particulate heat adhesive resin. Moreover, the Oken type air permeability measured according to JISP 8121-2: 2012 is 700 seconds or less in the sterile paper 1.

In the present embodiment, as described above, the sterile paper 1 is realized in which the heat adhesive layer 3 contains the particulate heat adhesive resin and the Oken type air permeability is 700 seconds or less. When the heat adhesive layer 3 contains particulate heat adhesive resin, the heat adhesive layer 3 is easily coagulated and peeled when peeling the sterile paper 1, and therefore, the occurrence of substrate breakage in the paper substrate 2 is suppressed. be able to. In addition, because it has good air permeability, not only the radiation sterilization method that irradiates and sterilizes by radiation, but also the air permeability of sterilization paper such as gas sterilization method using sterilization gas and high-pressure steam sterilization method using steam is required It becomes possible to apply also to the sterilization method. For this reason, according to the present embodiment, it is possible to realize sterile paper that can be applied to various sterilization methods while suppressing base material destruction at the time of peeling. In addition, base material destruction includes fuzzing and peeling of the paper base material.
In addition, since the cohesiveness can be generated in the thermal adhesive layer 3 when peeling the sterile paper 1 in this way, the thermal adhesive layer 3 is formed on the adherend side after the sterile paper 1 is peeled from the adherend. It will remain. This makes it possible to easily confirm that the sterile paper 1 and the adherend adhere uniformly.

  Hereinafter, the sterile paper 1 and the sterile package according to the present embodiment will be described in detail.

(Sterile paper)
As shown in FIG. 1, the sterile paper 1 of the present embodiment includes a paper base 2 and a heat adhesive layer 3 laminated on at least one surface of the paper base 2. The sterile paper 1 is thermocompression-bonded to an adherend such as, for example, a packaging paper, a film, or a shaped container for sterilization to form a sterile package. Examples of adherends include polyolefins exemplified by polyethylene and polypropylene, polyesters exemplified by polyethylene terephthalate, polyvinyl chloride, polyvinylidene chloride, ethylene / vinyl acetate copolymer resin, ethylene / acrylic copolymer resin or A film or a molded container for sterilization, which is constituted by such a laminate or the like can be mentioned. The sterile package has a space for containing a container such as a medical device, for example, between the sterile paper 1 and the adherend, which are thermocompression-bonded to each other. The medical device as the contents is not particularly limited as long as it is a medical device which is required to be sterilized before use, but can be exemplified by a needle, syringe, catheter, glove, scalpel, forceps, forceps, scissors, etc. . In the present embodiment, for example, in a state where the contents are accommodated in a sterile package, the contents are sterilized by a sterilization method such as an autoclave, ethylene oxide gas (EOG) sterilization, or γ-ray sterilization. Then, when using the sterilized contents, the sterilization paper 1 is peeled from the adherend to take out the contents. The heat adhesive layer 3 may be formed only on one side of the paper substrate 2 or may be formed on one side and the opposite side.

(Paper base)
The paper base 2 is obtained, for example, by making a papermaking material containing a pulp slurry.
Examples of pulp used for the pulp slurry include wood pulp and non-wood pulp. As wood pulp, softwood pulp, hardwood pulp and the like may be mentioned, and any may be used. In addition, the method of digesting wood pulp and the method of bleaching are not particularly limited. Examples of non-wood pulp include hemp pulp, kenaf pulp and bamboo pulp. One of these pulps may be used alone, or two or more thereof may be used in combination.
Materials other than pulp fibers, such as rayon fibers, nylon fibers, and other heat fusion fibers, can also be blended into pulp slurry as secondary materials.

The pulp slurry is obtained by beating the pulp in the presence of water.
The pulp beating method and the beating apparatus are not particularly limited. For example, a double disc refiner (DDR) having high beating efficiency is preferably used.
The beating of the pulp can be performed so that the freeness of the pulp (hereinafter, also referred to as "standard freeness") measured according to JIS P 8121-2: 2012 becomes 250 mL or more and 700 mL or less, and 250 mL or more and 600 mL or less It is more preferable to perform so that it may become and it is more preferable to perform a bet so that it may become 300 mL or more and 500 mL. By setting the standard freeness of the pulp to the above lower limit or more, the air permeability of the paper can be more effectively improved. Further, by setting the standard freeness of the pulp to the upper limit value or less, the strength of the paper can be improved to contribute to the improvement of the easy peelability.
In general, with regard to the relationship between pulp beating and paper strength, it is difficult to obtain paper strength in a state where it is not recommended to be enough refined, because the binding between pulp fibers is weak and the point of interfiber bonding (hydrogen bonding) is also small. It is thought that the paper strength is improved by advancing the beating to some extent. On the other hand, when the beating is continued, the binding between the pulp fibers is increased, and the point of interfiber bonding is increased. Thus, although the paper strength is obtained, the voids of the fibers decrease and the air permeability of the base paper decreases. If the standard freeness of the pulp is in the above-mentioned range, the paper strength can be sufficiently increased while maintaining the air permeability of the paper substrate 2, and the easy peelability of the sterile paper 1 can be further improved. It becomes.

  In the present embodiment, various internal chemicals for paper making can be added to the pulp slurry obtained by, for example, beating to prepare a papermaking material. Examples of internal additives include various fixing agents such as sizing agents, paper strength agents, wet paper strength agents, sulfate bands, cationized starch and the like. In addition to the above, water retention agents, retention aids, antifoaming agents, fillers, coloring agents and the like can be optionally added to the papermaking material as internal additives.

The paper strengthening agent can include one or more selected from, for example, polyacrylamide resin, cationized starch, polyvinyl alcohol and the like. Among these, a polyacrylamide resin-based paper strength agent is internally added to the paper substrate 2 to contain the polyacrylamide resin in the paper substrate 2, thereby more effectively improving the strength of the paper substrate 2. It is possible to further improve the easy peelability. Moreover, in order to have a paper-strengthening effect after addition, it is preferable that a mass mean molecular weight is 2 million (Mw) or more. In addition, it is preferable that the mass average molecular weight is 10,000,000 (Mw) or less because the viscosity is high in operation and the addition becomes difficult. In addition, the said mass mean molecular weight of polyacrylamide resin is a polyethylene oxide conversion value measured by gel permeation chromatography (GPC). Moreover, as a polyacrylamide resin as a paper strengthening agent, for example, an anionic, cationic, amphoteric or nonionic polyacrylic resin can be used, but it is particularly preferable to use an amphoteric polyacrylamide resin.
As the sizing agent, those known as sizing agents can be used, and one or more selected from, for example, alkenyl succinic acid, alkyl ketene dimer, rosin and the like can be included. In addition, as the wet paper strength agent, those known as wet paper strength agents can be used, and one or more selected from, for example, polyamide epoxy resin, epichloro resin, and melamine resin etc. it can. As a water retention agent, for example, carboxymethylcellulose can be used. As a filler, for example, talc can be used.

The basis weight of the paper substrate 2 is, for example, preferably 30 g / m ² or more, more preferably 40 g / m ² or more, and still more preferably 45 g / m ² or more. If the basis weight of the paper base material 2 is equal to or more than the lower limit value, the strength which can endure peeling of the sterile paper 1 is easily obtained, and the base material breakage at the time of peeling becomes even more difficult. Although the basis weight of the upper limit of the paper substrate 2 is not particularly limited, but is preferably from the viewpoint of air permeability is 300 g / ^{m 2} or less, more preferably 250 g / ^{m 2,} more preferably 200 g / ^{m 2} or less . The basis weight of the paper base 2 is measured, for example, in accordance with JIS P 8124: 2011.

Density of the paper substrate 2, for example, is preferably 0.50~1.20g / cm ^3, more preferably 0.65~1.10g / cm ^3. If the density of the paper substrate 2 is equal to or more than the lower limit value, it is easy to obtain strength that can withstand easy peel, and breakage of the substrate at peeling becomes even more difficult. If the density of the paper substrate 2 is equal to or less than the upper limit value, air permeability can be maintained. The density of the paper substrate 2 can be calculated from the measured values of thickness and basis weight, for example, by measuring the thickness according to JIS P 8118: 1998.

(Heat bonding layer)
The heat adhesive layer 3 is made of a heat adhesive resin. In the present embodiment, as described above, the heat adhesive layer 3 contains a particulate heat adhesive resin (hereinafter also referred to as a particulate heat adhesive resin). Thereby, it is possible to suppress the occurrence of substrate breakage while improving the air permeability of the sterile paper 1. In the present embodiment, for example, a plurality of particulate heat adhesive resins are contained in the heat adhesive layer 3. The plurality of particulate heat adhesive resins contained in the heat adhesive layer 3 may, for example, be in contact with or bonded to one another, or may be present as clusters. Further, the shape of the particulate heat adhesive layer is not particularly limited, but it is particularly preferable that the particulate heat adhesive resin having a substantially spherical or substantially ellipsoidal shape is contained, from the viewpoint of improving air permeability and suppressing breakage of the substrate. preferable.

In the manufacture of a sterile paper in which a heat adhesive layer is provided on a paper substrate, for example, a step of applying a heat adhesive resin on a paper substrate and drying by heating is performed. However, up until now, no consideration has been made on carrying out this process so that the particulate heat adhesive resin remains in the heat adhesive layer. For this reason, it was difficult to suppress that a base material destruction arises, improving air permeability.
In the present embodiment, the thermoadhesive layer containing the particulate thermoadhesive resin is provided on the paper substrate for the first time by appropriately adjusting the manufacturing conditions of the sterilized paper based on the results of the inventors' intensive studies. Sterilized paper is realized. For example, the manufacturing conditions such as the type of heat adhesive resin to be applied to the paper substrate, the particle diameter, physical properties such as glass transition temperature and minimum film forming temperature, and drying conditions of the applied heat adhesive resin are adjusted. However, it is believed that it may affect the retention of the particulate heat adhesive resin. In this manner, the present embodiment newly realizes sterile paper capable of suppressing occurrence of substrate breakage while improving air permeability.

  The heat adhesive layer 3 can contain, for example, a particulate heat adhesive resin with a particle diameter of 3 μm or more, and more preferably contains a particulate heat adhesive resin with a particle diameter of 5 μm or more. Thus, the inclusion of the heat-adhesive resin having a relatively large particle diameter facilitates the formation of voids between the particulate heat-adhesive resins, which can contribute to the improvement of air permeability. Moreover, the base-material destruction at the time of peeling the sterile paper 1 can be suppressed more effectively. On the other hand, the thermal adhesive layer 3 is not particularly limited, but preferably contains, for example, a granular thermal adhesive resin having a particle diameter of 30 μm or less, and more preferably contains a granular thermal adhesive resin having a particle diameter of 15 μm. Thereby, the heat sealability to the adherend of sterilization paper 1 can further be improved.

Further, granular heat adhesive resin contained in the heat-bonding layer 3, for example it is preferred that the average particle diameter D ₅₀ is 3μm or more, and more preferably 5μm or more. Thereby, the balance of the improvement of the air permeability in the sterilization paper 1 and suppression of a base-material destruction can be improved more effectively. On the other hand, the particulate heat adhesive resin contained in the heat adhesive layer 3 preferably has an average particle diameter D ₅₀ of, for example, 15 μm or less, and more preferably 13 μm or less. Thereby, the heat sealability to the adherend of sterilization paper 1 can further be improved. In addition, the average particle diameter D ₅₀ of the particulate heat adhesive resin is, for example, observing an arbitrary region of 50 μm × 50 μm of the thermal adhesive layer 3 with an electron microscope, and selecting 100 particulate heat adhesive resins from the region it can be obtained by calculating the average particle diameter D ₅₀ thereof was.

  With respect to the particle diameter of the particulate heat adhesive resin contained in the heat adhesive layer, for example, the type of heat adhesive resin to be applied to a paper substrate, particle diameter, glass transition point, Vicat softening point, minimum film forming temperature, etc. It is possible to control by adjusting the production conditions such as the physical properties of and the drying conditions of the applied heat-adhesive resin.

  The thermal adhesive resin contained in the thermal adhesive layer 3 has, for example, a glass transition point of 70 ° C. or higher. Thereby, even when the emulsion-type heat-adhesive resin applied as described later is dried by heating, it is easier to maintain the heat-adhesive resin in a granular shape. For this reason, it becomes possible to contribute to the improvement of the balance of the improvement of the air permeability in sterilization paper 1, and control of a substrate destruction. Moreover, it is more preferable that the glass transition point of heat bondable resin is 75 degreeC or more. On the other hand, the glass transition point of the heat adhesive resin is preferably, for example, 180 ° C. or less from the viewpoint of improving the heat sealability of the sterile paper 1 to the adherend. The glass transition point can be measured, for example, using differential scanning calorimetry or the like.

  The thermal adhesive resin contained in the thermal adhesive layer 3 has, for example, a minimum film forming temperature of 70 ° C. or higher. Thereby, even when the emulsion-type heat-adhesive resin applied as described later is dried by heating, it is easier to maintain the heat-adhesive resin in a granular shape. For this reason, it becomes possible to contribute to the improvement of the balance of the improvement of the air permeability in sterilization paper 1, and control of a substrate destruction. Further, the minimum film formation temperature of the heat adhesive resin is more preferably 75 ° C. or more. On the other hand, the minimum film forming temperature of the heat adhesive resin is preferably, for example, 180 ° C. or less from the viewpoint of improving the heat sealability of the sterile paper 1 to the adherend.

  The heat adhesive resin contained in the heat adhesive layer 3 is, for example, one or a selected from ethylene- (meth) acrylic acid copolymer, ethylene-vinyl acetate copolymer, acrylic acid ester polymer, polyethylene, and polybutene. Two or more can be included. Thereby, it becomes easier to realize the thermal adhesive layer 3 containing the granular thermal adhesive resin. For this reason, it becomes possible to contribute to the improvement of the balance of the improvement of the air permeability in sterilization paper 1, and control of a substrate destruction. Among these, one or two or more of an ethylene- (meth) acrylic acid copolymer, an ethylene-vinyl acetate copolymer, and an acrylic acid ester polymer are included to provide the heat sealability of the sterile paper 1 It is more preferable from the viewpoint of improving. In this embodiment, for example, the case where both an ethylene-vinyl acetate copolymer and an acrylic ester polymer are contained as a heat-adhesive resin can be mentioned as one of the preferable modes. Further, from the viewpoint of contributing to the improvement of the balance between the improvement of the air permeability and the suppression of the destruction of the base material, the ethylene- (meth) acrylic acid copolymer or the ethylene-vinyl acetate copolymer is used as the thermal adhesive layer 3 It is more preferable to include as a main component of In addition, containing as a main component means that 60 mass% or more is contained with respect to the thermal adhesive layer 3 whole, for example.

  The heat adhesive layer 3 can include, for example, other components other than the heat adhesive resin. In the present embodiment, the content of the heat adhesive resin with respect to the entire heat adhesive layer 3 is, for example, preferably 80% or more, and more preferably 90% or more. Thereby, the heat sealability of the sterile paper 1 can be more effectively improved. On the other hand, the upper limit of the content of the heat adhesive resin with respect to the entire heat adhesive layer 3 is not particularly limited, and can be, for example, 100% by mass.

  In the present embodiment, it is preferable that no other layer is provided between the paper base 2 and the heat adhesive layer 3. This can reduce the manufacturing cost. According to the present embodiment, even in the case where the thermal adhesive layer 3 is formed directly on the paper substrate 2 in this manner, good heat sealability and air permeability can be achieved while suppressing destruction of the substrate at the time of peeling. It is possible to realize the sterilizing paper which it has. In addition, another layer may be provided between the paper base 2 and the heat adhesive layer 3, for example. Although it does not specifically limit as another layer, For example, the undercoat layer etc. which contain a polyacrylamide resin can be mentioned.

  The method for producing the sterile paper 1 according to the present embodiment includes, for example, a step of preparing a paper substrate 2 and a heat adhesive resin or a resin composition containing the same applied to the paper substrate 2 and dried. Forming a thermal adhesive layer 3 containing an adhesive resin on the paper substrate 2. In the present embodiment, for example, the heat adhesive resin or the resin composition containing the same is applied only to one side of the paper base 2 and not applied to the other side, or the heat is applied to one side and the other side of the paper base 2 The case where the adhesive resin or the resin composition containing the same is applied may be mentioned. In addition, the said resin composition points out the composition containing heat bondable resin and another component. The other components are not particularly limited, and those which can be generally used as materials constituting the heat adhesive layer of sterile paper can be used.

  In the present embodiment, a water-based heat sealing agent in which a heat adhesive resin or a resin composition containing the same is dispersed in water may be applied to the paper substrate 2, and the heat adhesive resin or a resin composition containing the same A solvent-based heat sealing agent in which the solvent is dispersed in a solvent may be applied to the paper substrate 2. Examples of the water-based heat sealing agent include ethylene-vinyl acetate copolymer emulsion, ethylene- (meth) acrylic acid copolymer emulsion, acrylic acid ester polymer emulsion, polyethylene emulsion, polyethylene-polybutene mixed emulsion, etc. . Among these, ethylene-vinyl acetate copolymer emulsion, acrylic ester emulsion and polyethylene emulsion express stable peeling force and do not increase the burst strength measured according to ISO 2758 on the paper substrate surface. It is preferable because it has a high effect of suppressing the buildup.

In case of coating an emulsion-type thermal adhesive resin as described above, the average particle diameter D ₅₀ of the emulsion-type heat-adhesive resin is preferably for example at 3μm or more, and more preferably 5μm or more. Thus, by using the emulsion-type heat-adhesive resin having a relatively large particle diameter, it becomes easier to include the particulate heat-adhesive resin in the heat-adhesive layer 3. For this reason, it can contribute to the improvement of the balance of the improvement of air permeability and suppression of base-material destruction. On the other hand, an emulsion-type heat-adhesive resin is, for example, preferably have an average particle diameter D ₅₀ is 15μm or less, and more preferably less 13 .mu.m. Thereby, the heat sealability to the adherend of sterilization paper 1 can further be improved.

  The glass transition point and the minimum film forming temperature of the heat adhesive resin applied to the paper substrate 2 are similar to, for example, the glass transition point and the minimum film forming temperature of the heat adhesive resin contained in the above-described heat adhesive layer 3 It is preferable from the viewpoint of improving the balance between the improvement of the heat sealability in the sterile paper 1, the improvement of the air permeability, and the suppression of the substrate breakage in the range.

The application of the heat-adhesive resin or resin composition is not particularly limited, and can be performed using various known wet application methods. For example, it can be carried out using an on-machine size press apparatus of a paper machine, a transfer roll coater (a shim sizer, a gate roll coater, etc.), a spray apparatus or the like. In the off-machine, a general coating apparatus such as a blade coater, an air knife coater, a roll coater, a reverse roll coater, a shim sizer, a gate roll coater, a bar coater, a curtain coater, a slot die coater, a gravure coater, a chamber coater The coating can be performed using a brush coater, a two-roll coater, a bill blade coater, a short dwell coater, or the like. With regard to drying equipment, drying with an air dryer or an infrared heater that does not contact the coated surface is preferable from the viewpoint of reliably suppressing contamination of the equipment, but direct contact with the coated surface using a cylinder drier may also be used. it can.
In consideration of the operability and productivity, the application and drying of the heat-adhesive resin or resin composition is preferably performed on an on-machine basis. Therefore, with regard to the type of paper machine for making the paper substrate, there are no particular limitations on the type of the fourdrinier paper machine, the fourdrinier paper machine, the cylinder paper machine, etc., but the on-machine coater is equipped It is preferable to use the following.

  Drying of the heat-adhesive resin or resin composition is preferably performed, for example, under conditions of 60 to 130 ° C. and 30 seconds to 10 minutes. As a result, it becomes easier to include the heat-adhesive resin in the heat-adhesive layer 3 that retains the granular shape even after drying.

The coating amount of the heat adhesive resin is not particularly limited, and is appropriately selected according to the material of the adherend to which the heat adhesive layer 3 is bonded and the heat sealing conditions. In the present embodiment, the coating amount is, for example, preferably 0.1 g / m ² or more, and more preferably 0.3 g / m ² or more. This makes it easy to obtain a satisfactory heat adhesion. For example, when heat-bonded as a sterile bag, sterile paper is difficult to peel off. On the other hand, the coating amount is, for example, preferably 30 g / m ² or less, and more preferably 10 g / m ² or less. Thereby, destruction of the paper base material 2 does not occur easily at the time of easy peeling. In addition, the thermal adhesive layer 3 hardly develops spinnability, and contamination of the contained substance hardly occurs. In the present embodiment, the coating amount is 3 g / m ² , particularly from the viewpoint of improving the heat sealability of the sterile paper 1 and from the viewpoint of leaving the thermal adhesive layer 3 on the adherend side after peeling the sterile paper 1. The amount can be set to 5 g / m ² or more, and more preferably 6 g / m ² or more. Heretofore, it has been difficult to realize sterile paper having sufficient air permeability when the coating amount is as high as 3 g / m ² or more. According to the present embodiment, since the particulate heat adhesive resin is contained in the heat adhesive layer 3, it is possible to realize good air permeability even when such a high coating amount is employed. . In addition, the coating amount of heat adhesive resin is substantially equal to the dry application amount, when apply | coating emulsion type heat adhesive resin.

  In the present embodiment, the Oken type air permeability, which is measured according to JIS P 8121-2: 2012, is preferably 700 seconds or less, more preferably 300 seconds or less according to JIS P 8121-2: 2012. And 100 seconds or less are particularly preferable. Thereby, the sterilizing paper 1 can be suitably applied also in the gas sterilization method using sterilizing gas, the high pressure steam sterilization method using steam, etc. where the air permeability of the sterilizing paper is required. Therefore, it is possible to realize the sterile paper 1 applicable to various sterilization methods such as the radiation sterilization method, the gas sterilization method, and the high-pressure steam sterilization method. On the other hand, the lower limit value of the Oken type air permeability is not particularly limited, but can be set to, for example, 3 seconds. Such an air permeability can be realized by including a particulate heat adhesive resin in the heat adhesive layer 3. In addition, the type and coating amount of the heat adhesive resin, drying conditions, the particle diameter of the particulate heat adhesive resin contained in the heat adhesive layer 3, the freeness of pulp, the basis weight of the paper substrate 2 and the like are appropriately selected. It is possible to control the above-mentioned air permeability by doing.

  In the present embodiment, the sterile package obtained by thermocompression bonding the sterile paper 1 and the adherend has a peel strength when the adherend is peeled 180 ° at a peel speed of 300 m / min according to JIS P 8113: 2006. Is, for example, 200 to 1,500 gf / 15 mm. Thereby, a sterile package excellent in balance between easy peelability and heat sealability can be obtained. From the viewpoint of more effectively improving the balance between easy peelability and heat sealability, the peel strength is more preferably 250 to 1000 gf / 15 mm. The peel strength is controlled by appropriately selecting, for example, the amount and type of the heat adhesive resin, the drying conditions, the particle diameter of the particulate heat adhesive resin contained in the heat adhesive layer 3 and the like. Is possible. The adherend is, for example, a packaging paper, a film, or a shaped container for sterilization.

  According to the present embodiment, air permeability can be improved while suppressing the destruction of the base material at the time of peeling as described above. Further, since the paper substrate 2 is difficult to tear when peeling the sterile paper 1 in this way, when peeling the sterile paper 1 from the adherend by the easy peel method, the whole can be peeled at once. Further, since fluffing and peeling of the paper sheet are suppressed, it is possible to prevent the fibers dropped from the fluffed portion and the peeled paper piece from adhering to the adherend or the contained object.

  Furthermore, sterilization methods of sterilization paper include autoclave, ethylene oxide gas (EOG) sterilization, and some sterilization methods such as gamma ray sterilization, but in particular, EOG sterilization needs to carry out gas replacement after sterilization. Since the sterile paper according to the present embodiment can realize good air permeability as described above, it is possible to realize sterile paper particularly suitable for EOG sterilization.

  Moreover, according to the present embodiment, the sterile paper 1 can also have easy peelability. As a result, it is possible to provide a sterile paper that can be used in an operating room with a high degree of cleanliness while suppressing nicks at the time of exfoliation. Also, the air permeability of the sterile paper 1 can be increased, and the time for replacing the sterile gas after sterilization with air can be shortened. Thus, the sterilized paper of the present invention is also extremely useful in practice, which is excellent in the balance between easy peelability and air permeability.

  As mentioned above, although the sterile paper 1 which concerns on this embodiment was demonstrated, this invention is not limited to the said embodiment. The configurations and combinations thereof in the above embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention. For example, another layer may be provided between the paper base 2 of the sterile paper 1 and the heat adhesive layer 3. Examples of the other layers include a water vapor barrier layer, an oxygen barrier layer, a print layer, a printability improving layer, an overprint layer, a light shielding layer and the like. The other layer provided between the paper substrate 2 and the thermal adhesive layer 3 may be one layer or two or more layers. Moreover, you may have a printing layer on both surfaces of the paper base material 2 in the range in which an air permeability and peeling strength do not deviate from the meaning of this invention. It may further have an overprint layer on the print layer.

  The present invention will be specifically described by way of examples. The present invention is not limited to these examples.

Example 1
[Production of paper base material]
Hardwood bleached kraft pulp (LBKP) was beaten with DDR to 350 mL of Canadian standard freeness (freeness) described in JIS P 8121-2: 2012 to obtain a pulp slurry. An alkenylsuccinic acid sizing agent (FiBlan 81 K) dispersed as an internal additive chemical in the pulp slurry with 0.5% of sulfuric acid band by absolute drying, cationized starch (Pillar 3 YK, manufactured by Pillar Starch Co., Ltd.) in advance. Arakawa Chemical Industries, Ltd. 0.05%, Amphoteric polyacrylamide-based resin paper strength agent (PAM) (trade name: Polystron OFT-3, manufactured by Arakawa Chemical Industries, mass average molecular weight 3,000,000) 0.7% Then, an epichloro resin wet paper strengthening agent 0.4% was added to obtain a papermaking material. The papermaking raw material was paper machined by means of a Fourdrinier paper machine to obtain a base paper. Thus, a paper base having a basis weight of 60 g / m ² and a density of 0.7 g / cm ³ was obtained.

[Production of sterile paper]
100 parts by weight of ethylene-vinyl acetate copolymer emulsion (Kemipearl V 200, manufactured by Mitsui Chemical Co., Ltd., glass transition temperature 85 ° C, average particle diameter 7μm, minimum film forming temperature 80 ° C) which is a heat sealing agent, by water It diluted and obtained the coating liquid. Next, the coating solution was applied to one surface of the paper substrate obtained above using a bar coater, and dried with a blow dryer under conditions of 105 ° C. for 1 minute to form a thermal adhesive layer. Here, it applied so that the application amount of the heat sealing agent after drying might be 10.0 g / m < ² >. This gave a sterile paper.

The heat adhesive layer of the obtained sterilized paper was observed by an electron microscope, and it was confirmed that the heat adhesive layer had the above-mentioned heat sealing agent in the form of particles. In addition, it was also confirmed that the heat sealing agent in the form of particles having a particle diameter of 3 μm to 30 μm was present in the heat adhesive layer. The average granular thermally adhesive resin particle diameter D ₅₀ contained in the heat-bonding layer was in the range of about 8μm or less than about 4 [mu] m. FIG. 2 is an electron micrograph of the heat adhesive layer of the sterile paper according to the first embodiment. It can also be seen from FIG. 2 that the heat adhesive layer of the sterilized paper according to the present invention contains granular heat adhesive resin.

Example 2
A paper substrate and a sterilized paper were produced in the same manner as in Example 1 except that the freeness of pulp was changed to 250 mL in the production of the paper substrate of Example 1.

Example 3
A paper substrate and a sterilized paper were produced in the same manner as in Example 1 except that the basis weight of the paper substrate was changed to 40 g / m ² in the production of the paper substrate of Example 1.

Example 4
A paper substrate and a sterilized paper were produced in the same manner as in Example 1 except that the basis weight of the paper substrate was changed to 150 g / m ² in the production of the paper substrate of Example 1.

Example 5
A paper substrate in the same manner as in Example 1 except that in the production of the sterilized paper of Example 1, the coated amount of the heat seal agent after drying on one side of the paper substrate is 1.0 g / m ² . A sterile paper was made.

Example 6
[Production of paper base material]
A paper base was produced in the same manner as Example 1.

[Production of sterile paper]
80 parts by mass of ethylene-vinyl acetate copolymer emulsion (Chemipearl V200, manufactured by Mitsui Chemicals, glass transition temperature 80 ° C., average particle diameter 7 μm), and acrylic emulsion (Yodosol AE-41, manufactured by Henkel Japan Ltd., glass transition temperature 5 A heat sealing agent was obtained by mixing 20 parts by mass of ° C and an average particle size of 0.6 μm. Next, a heat sealing agent was applied to one side of the paper substrate obtained above using a bar coater, and dried with a blow dryer under conditions of 105 ° C. for 1 minute to form a heat adhesive layer. Here, it applied so that the application amount of the heat sealing agent after drying might be 10.0 g / m < ² >. This gave a sterile paper.

Example 7
In the production of the sterile paper of Example 1, the coating solution is applied so that the applied amount of the heat sealing agent after drying is 5.0 g / m ² and dried with a cylinder drier at 80 ° C. for 3 minutes. A thermal adhesive layer was formed. A paper base and sterile paper were produced in the same manner as in Example 1 except for the above.

Example 8
100 parts by mass of ethylene-vinyl acetate copolymer emulsion (Kemipearl V200, manufactured by Mitsui Chemicals, Inc., glass transition temperature 85 ° C., average particle diameter 7 μm), which is a heat sealing agent, in the production of the sterilized paper of Example 7; 40 parts by mass of a 3% aqueous solution (Cellogen AG gum, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was mixed to obtain a coating solution. And it apply | coated so that the application quantity of the heat sealing agent after drying might be 3.6 g / m < ² > on one surface of the paper base material which obtained this coating liquid. A paper base and sterile paper were produced in the same manner as in Example 7 except for the above.

  About Examples 2-8, when the heat-bonding layer of the obtained sterilized paper was observed with the electron microscope, it was confirmed that the heat-bonding layer has a granular heat sealing agent. In addition, it was also confirmed that a granular heat sealing agent having a particle diameter of 3 μm or more was present in the heat adhesive layer.

Comparative Example 1
[Production of paper base material]
A paper base was produced in the same manner as Example 1.

[Production of sterile paper]
50 parts by mass of ethylene-vinyl acetate copolymer emulsion (trade name: EA-H700, manufactured by Toyo Ink Co., Ltd., particle size: 0.8 μm or less), and acrylic emulsion (trade name: Yodosol AE-41, manufactured by Henkel Japan Ltd., particles The heat sealing agent obtained by mixing 50 parts by mass of particles having a diameter of 0.6 μm or less was diluted to 20% with water to prepare a coating solution. Next, the coating liquid was applied to one surface of the paper substrate obtained above using a bar coater, and dried with a blow dryer under conditions of 105 ° C. for 1 minute to form a thermal adhesive layer. Here, it applied so that the application amount of the heat sealing agent after drying might be 10.0 g / m < ² >. This gave a sterile paper.

  When the heat adhesive layer of the obtained sterilized paper was observed by an electron microscope, it was confirmed that the heat adhesive layer did not have a granular heat sealing agent.

Comparative Example 2
[Production of paper base material]
A paper base was produced in the same manner as Example 1.

A coating solution was prepared by diluting an ionomer heat sealing agent (trade name: Chemipal S200, manufactured by Mitsui Chemicals, Inc., average particle diameter 0.5 μm, glass transition temperature 55 ° C.) to 20% with water. Next, the coating liquid was applied to one surface of the paper substrate obtained above using a bar coater, and dried with a blow dryer under conditions of 105 ° C. for 1 minute to form a thermal adhesive layer. Here, it applied so that the application amount of the heat sealing agent after drying might be 10.0 g / m < ² >. This gave a sterile paper.

  When the heat adhesive layer of the obtained sterilized paper was observed by an electron microscope, it was confirmed that the heat adhesive layer did not have a granular heat sealing agent.

[Measurement of Oken type air permeability]
The Oken-type air permeability of the obtained sterilized paper was measured according to JIS P 8121-2: 2012 for each example and each comparative example.

[Peeling test]
For each example and each comparative example, the obtained sterile paper and the composite film of polyethylene terephthalate (PET) resin and polyethylene (PE) resin are in contact with the polyethylene resin side of the surface on the heat adhesive layer side of the sterile paper Then, using the heat press tester, a thermo-compression-bonded product was produced under the thermo-compression bonding conditions of 150 ° C., 3.0 kgf / cm ² , and 1.1 seconds.

  The thermocompression-bonded material prepared by the above method was cut into a width of 15 mm to prepare a peel strength measurement sample. The peel strength (gf / 15 mm) of the obtained sample for measurement of peel strength was measured according to JIS P 8113: 2006 using a tensile tester (model: Tensilon RTC-1250A, manufactured by Orientec Co., Ltd.) It measured by chucking the edge part of each of PE composite film and sterile paper, and peeling by a peeling speed of 300 mm / min by 180 degree peel method.

Moreover, in the case of the measurement of peeling strength, the state of the base-material destruction of sterile paper was confirmed visually, and the following references | standards evaluated.
:: substrate failure did not occur.
Δ: Sterile paper could be peeled off, but sticking of paper pieces and wrinkles was observed on the PET / PE film.
X: Substrate breakage occurred.

  In Table 1, the evaluation result of the coating amount of a heat sealing agent, the Oken type air permeability, peeling strength, and the state of base-material destruction is shown about Examples 1-7 and Comparative Examples 1-2, respectively.

As shown in the above results, the sterilized paper of Examples 1 to 8 has a low air permeability of 700 seconds or less, and is also suitable for a sterilization method requiring gas permeability to sterilized paper such as gas sterilization method or high pressure steam sterilization method. Could be used for The sterile papers of Examples 1 to 8 had a peel strength of 200 to 1500 gf / 15 mm in the peel test, and the evaluation result of the state of the substrate fracture in the peel test was ○. From these results, it can be seen that sterile paper applicable to various sterilization methods has been obtained while suppressing substrate destruction. Moreover, in each Example, it was also confirmed that a sterile paper excellent in easy-peel suitability was obtained.
On the other hand, in Comparative Examples 1 and 2, the air permeability exceeded 700 seconds. Moreover, about the comparative example 1, the evaluation result of the state of a base material destruction was x.

1 Sterilized paper 2 Paper substrate 3 Thermal adhesive layer

Claims (5)

A paper substrate and a heat adhesive layer laminated on one side of the paper substrate,
The heat adhesive layer comprises a particulate heat adhesive resin,
Oken type air permeability measured according to JIS P 8121-2: 2012 is 700 seconds or less ,
The minimum film forming temperature of the heat adhesive resin is 70 ° C. or more and 180 ° C. or less,
The heat adhesive layer includes a particulate heat adhesive resin having an average particle diameter D50 of 3 μm to 15 μm ,
The heat-adhesive resin is one or two or more selected from ethylene- (meth) acrylic acid copolymer, ethylene-vinyl acetate copolymer, acrylic acid ester polymer, polyethylene, and polybutene . The sterile paper of claim 1 , wherein the paper substrate comprises a polyacrylamide resin. The sterilized paper according to claim 1 or 2, wherein the paper substrate is manufactured using a pulp having a freeness of 250 mL or more and 700 mL or less measured according to JIS P 8121-2: 2012. The sterilization packaging obtained by thermocompression-bonding the sterilization paper as described in any one of Claims 1-3 , and a packaging paper, a film, or the shaping | molding container for sterilization. From the sterile package, the packaging paper, the film, or the sterilization container for
The sterile package according to claim 4 , wherein the peel strength at the time of 180 ° peeling at a peeling rate of 300 m / min according to P 8113: 2006 is 200 to 1500 gf / 15 mm.

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