JP2018039911A - Thermally adhesive filter and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermally adhesive filter in which fungus shielding properties, air permeability and moisture permeability can be made consistent, also, thermal adhesion can be performed to the other member with strong adhesive power, further, the control of production conditions is easy, and production cost is low.SOLUTION: Provided is a thermally adhesive filter comprising an air permeable paper base material and a thermally adhesive particle layer(s) provided on at least either side of the paper base material, the thermally adhesive particle layer(s) includes the following thermally adhesive particles (I), and the ratio of the thermally adhesive particles (I) occupied in the dry solid content of the thermally adhesive particle layer(s) is 50 mass% or more. The thermally adhesive particle(s)(I): ethylene-vinyl acetate copolymer as a main component, the particles in which the particle diameter lies in the range of 1 to 30 μm.SELECTED DRAWING: None

Description

  The present invention relates to a heat-adhesive filter that can be thermally bonded to other members, prevents dust and bacteria in the outside air from entering, and has a function of transmitting purified air, and a method for manufacturing the same.

One method for cultivating edible fungi such as shiitake mushrooms and maitake mushrooms is fungus bed cultivation in which cultivation is carried out in a resin sheet bag called a fungus bed bag. In fungus bed cultivation, the medium is placed in an opened fungus bed bag, sterilized by high-pressure steam sterilization, etc., cooled, then planted with germs in a sterile room, and the fungus bed bag is sealed. Stop. Thereafter, cultivation is carried out by placing a bag for a fungus bed in an environment maintained at a temperature and humidity suitable for breeding bacteria.
During cultivation, it is necessary to supply oxygen and moisture from the outside air into the bag for the growth of edible fungi, but it is necessary to prevent the invasion of hyphae other than bacteria and breeding bacteria that inhibit the growth of edible fungi. is there. Therefore, as the microbial bed bag, a bag body in which a vent hole is formed and a filter is bonded so as to cover the vent hole is used.

The filter of the bag for fungus beds is bonded to the bag body by thermocompression bonding. Therefore, as a conventional filter, a heat-bondable porous plastic sheet or a resin nonwoven fabric has been used (for example, Patent Document 1).
However, when trying to obtain a high-performance resin filter that has both invasion prevention of germs and the like, air permeability and moisture permeability, there is a problem that adjustment of raw materials and production conditions is difficult and production cost increases.

There is paper as a material that can easily prevent invasion of various germs and the like and achieve air permeability and moisture permeability. However, the paper itself cannot be bonded to the bag body by thermocompression bonding.
If a thermal adhesive layer is provided on the paper substrate, thermal adhesion is possible. However, if a thermal adhesive layer is provided on the entire surface of the paper substrate, the air permeability and moisture permeability of the paper substrate are lost. In addition, if the thermal adhesive layer is provided in the form of dots or nets on the surface of the paper base, air permeability and moisture permeability can be ensured to some extent, but a gap is formed at the joint portion with the bag body, and the effect of preventing invasion of germs, etc. Adhesive strength is insufficient.
By providing a thermal adhesive layer only on the joint part of the paper substrate with the fungus bed bag, it is possible to maintain the invasion prevention effect and adhesive strength of germs, etc., but the position during partial application of the thermal adhesive layer and filter bonding Since matching and the like are necessary, there is a problem that the manufacturing process becomes complicated and the cost increases.

On the other hand, in the field of sterilized packaging, there is a demand for a thermoadhesive layer that can be thermocompression-bonded so that it can be easily opened and that can maintain air permeability even when applied to the entire surface of the air-permeable substrate. For example, Patent Document 2 discloses a sterilized packaging body in which a thermal adhesive layer containing polyethylene-based fine particles is formed (Patent Document 2).
However, the filter at the vent of the microbial bed bag must not be easily peeled off from the bag body, and must be firmly bonded. Usually, in a microbial bed bag, since the thermocompression bonding of the bag body and the filter is performed with a narrow width of about 1 to 2 mm, particularly strong adhesive force is required. For this reason, the thermal adhesive layer of Patent Document 2 cannot be formed on the surface of the paper substrate to provide a filter for the vent of the microbial bed bag.

JP 2005-124524 A Japanese Patent Laid-Open No. 1-153471

  In view of the above circumstances, the present invention can achieve both antibacterial properties, air permeability, and moisture permeability, can be thermocompression bonded to other members with a strong adhesive force, and can be easily adjusted for manufacturing conditions, with low manufacturing cost. It is an object to provide an adhesive filter.

In order to achieve the above object, the present invention employs the following configuration.
[1] A gas permeable paper base material, and a thermal adhesion particle layer provided on at least one surface of the paper base material,
The thermal adhesive particle layer is composed mainly of the following thermal adhesive particles (I).
Thermal adhesive particles (I): particles having an ethylene vinyl acetate copolymer as a main component and a particle diameter in the range of 1 to 30 μm.
[2] The thermal adhesive filter according to [1], wherein the pulp constituting the paper base has a freeness defined by JIS P 8121-2: 2012 of 300 to 700 mL.
[3] The thermal adhesive filter according to [1] or [2], wherein the basis weight of the paper base is 15 to 200 g / m ² .
[4] The thermal adhesive filter according to any one of [1] to [3], wherein the paper base material includes a wet paper strength enhancer.
[5] The thermal adhesive filter according to any one of [1] to [4], wherein a dry coating amount of the thermal adhesive particle layer is 1 to ²⁰ g / m ² .
[6] The thermal adhesion particle layer is further selected from an acid-modified polyolefin resin, a chlorinated polyolefin resin, a chlorinated ethylene-vinyl acetate copolymer resin, an acid-modified chlorinated polyolefin resin, and an acrylic-modified chlorinated polyolefin resin. The thermal adhesive filter according to any one of [1] to [5], which contains one or more adhesion aids.
[7] The thermal adhesion particle layer further includes an ethylene (meth) acrylic acid copolymer, an ethylene-vinyl acetate copolymer (excluding the thermal adhesive particles (I)), an acrylate polymer, The thermal adhesive filter according to any one of [1] to [6], which contains one or more thermal adhesive resins (II) selected from polyethylene and polybutene.
[8] A thermal adhesive filter for forming a thermal adhesive particle layer by applying and drying a thermal adhesive particle layer coating liquid containing the following thermal adhesive particles (I) on at least one surface of a gas-permeable paper substrate A manufacturing method comprising:
The method for producing a heat-adhesive filter, wherein the proportion of the heat-adhesive particles (I) in the dry solid content of the coating liquid for the heat-adhesive particle layer is 50% by mass or more.
Thermal adhesive particles (I): particles having an ethylene vinyl acetate copolymer as a main component and a particle diameter in the range of 1 to 30 μm.

  The heat-adhesive filter of the present invention can achieve both antibacterial properties, gas permeability, and moisture permeability, can be thermocompression bonded with a strong adhesive force, can easily adjust the manufacturing conditions, and has a low manufacturing cost.

[Thermal adhesive filter]
The thermal adhesive filter of the present invention includes a gas-permeable paper base material and a thermal adhesive particle layer provided on at least one surface of the paper base material.

The heat-adhesive filter of the present invention has a paper base material having a Wangken air permeability (hereinafter simply referred to as “Wangan airflow”) defined in JIS P 8117: 2009 for 5 to 50 seconds. It is preferably 5-30 seconds, more preferably 5-20 seconds.
When the Oken air permeability is equal to or less than the preferable upper limit value, air and water vapor can be easily transmitted. Moreover, the filter which prevents invasion of various germs etc. can be easily manufactured because Oken type | formula air permeability is more than a preferable lower limit.

(Paper substrate)
As the paper substrate, a gas-permeable paper substrate is used. The Oken type air permeability of the paper substrate is preferably 5 to 50 seconds, more preferably 5 to 30 seconds, and still more preferably 5 to 20 seconds.
When the Oken type air permeability of the paper base material is equal to or less than the preferable upper limit value, it is easy to ensure the air permeability of the thermal adhesive filter. Moreover, when the Oken-type air permeability of the paper base material is equal to or more than a preferable lower limit value, a paper base material excellent in antibacterial properties can be easily produced.
The Oken type air permeability of the paper substrate can be adjusted mainly by the beating degree. Moreover, it can adjust also with the basic weight of a paper base material, and the kind of pulp which comprises a paper base material.

Examples of the pulp constituting the paper base include wood pulp and non-wood pulp. Wood pulp includes softwood pulp, hardwood pulp and the like. From the viewpoint of easily reducing the air permeability, 50% by mass or more of the total pulp constituting the paper base material is preferably hardwood pulp, and more preferably 80% by mass or more is hardwood pulp.
Non-wood pulp includes hemp pulp, kenaf pulp, bamboo pulp and the like. Materials other than pulp fiber, such as rayon fiber, nylon fiber, and other heat-bonding fibers, can be blended as auxiliary materials.

The paper base material is obtained by papermaking a papermaking raw material mainly composed of pulp slurry.
The pulp slurry is obtained from wood or non-wood raw material chips through steps such as cooking, washing and bleaching. There is no particular limitation on the cooking method, washing method, bleaching method and the like. The pulp slurry obtained through these steps is further beaten in the presence of water.

The beating method and beating apparatus are not particularly limited, but a double disc refiner (DDR) with high beating efficiency is preferably used.
The beating degree is preferably adjusted so that the freeness defined in JIS P 8121-2: 2012 (hereinafter also referred to as “standard freeness”) is 300 to 700 mL. That is, the paper base is preferably manufactured using pulp having a standard freeness of 300 to 700 mL.
The standard freeness is more preferably 350 to 600 mL, and further preferably 350 to 500 mL.
When the standard freeness is equal to or more than the preferred lower limit, the Oken air permeability of the paper substrate can be easily lowered. That is, it is easy to ensure the air permeability and moisture permeability of the paper substrate. In addition, when the standard freeness is equal to or less than the preferable upper limit value, a paper base material that becomes a dense filter with less unevenness in formation can be obtained. As a result, it is possible to suppress the occurrence of pinholes that reduce the bacteriostatic properties.

The paper substrate preferably contains a wet paper strength enhancer. For example, when a heat-adhesive filter is used as a filter for a mycelia bed bag, the filter is placed in a high-temperature and high-humidity environment that is a hyphae-growing environment for a long time. When the paper base material contains the wet paper strength enhancer, it is possible to prevent the filter from being damaged during use and losing bactericidal properties.
Examples of the wet paper strength enhancer include polyamide epichlorohydrin resin, melamine formaldehyde resin, urea formaldehyde resin, vegetable gum, latex, polyethyleneimine and the like. In particular, the polyamide epichlorohydrin resin can be used preferably because it can be used in a wide pH range and a high wet paper strength can be obtained with a low addition amount.

In combination with the wet paper strength enhancer, dry paper strength enhancers such as glyoxal, gum, mannogalactan polyethyleneimine, polyacrylamide resin, polyvinyl alcohol, starch, carboxymethylcellulose, guar gum, urea resin and the like may be used.
The wet paper strength enhancer and the dry paper strength enhancer are preferably added as an internal additive or an external additive, and more preferably as an internal additive, in the paper making process of paper base production.

The ratio of the wet paper strength enhancer to the dry solid content of the pulp constituting the paper substrate is preferably 0.1 to 3.0% by mass, more preferably 0.2 to 2.0% by mass. Preferably, it is 0.3-1.0 mass%.
By setting the ratio of the wet paper strength enhancer to a preferable lower limit value or more, sufficient durability can be obtained when used as a filter for a bag for a fungus bed in a high humidity environment. In addition, by setting the ratio of the wet paper strength enhancer to a preferable upper limit value or less, aggregates due to the wet paper strength enhancer are generated in the paper machine, and the risk that the paper base material is stained is reduced.

A paper making chemical such as a yield improver, a drainage improver, a sizing agent, and a filler may be added to the paper base as necessary.
The ratio of components other than pulp including the wet paper strength enhancer to the dry solid content of the pulp constituting the paper substrate is preferably 0.5 to 10% by mass, and 1.0 to 5.0% by mass. It is more preferable that it is 1.5-3.0 mass%.

The basis weight of the paper substrate is preferably 15~200g / m ^2, more preferably from 30 to 150 g / m ^2, further preferably 50 to 100 g / m ^2. By setting the basis weight of the paper base material to a preferable lower limit value or more, pinholes that cause invasion of various germs are less likely to occur. Moreover, the raise of the air permeability of a paper base material can be suppressed by making the basic weight of a paper base material into a preferable upper limit or less.
Density of the paper substrate is preferably 0.40 to 0.95 g / cm ^3, more preferably ^{0.50~0.80g / cm 3, 0.60~0.75g / cm} 3 More preferably. By setting the density of the paper substrate to a preferable lower limit value or more, pinholes that reduce the bacteriostatic properties are unlikely to occur. Moreover, the raise of the air permeability of a paper base material can be suppressed by making the basic weight of a paper base material into a preferable upper limit or less.

(Thermal bonding particle layer)
The heat-adhesive particle layer contains the heat-adhesive particles (I) as a main component, and if necessary, a heat-adhesive resin other than the heat-adhesive particles (I) (hereinafter referred to as “heat-adhesive resin (II)”). ), Adhesive aids, and other ingredients.

<Thermoadhesive particles (I)>
The heat-adhesive particles (I) are particles having an ethylene-vinyl acetate copolymer (hereinafter also referred to as “EVA”) as a main component and having a particle diameter in the range of 1 to 30 μm. The present inventors have found that by using EVA as a main component, a strong adhesive force can be obtained even when a particulate heat-adhesive resin is used.
When EVA is the main component, it means that the proportion of EVA in one particle is 80% by mass or more. The proportion of EVA in the particles is preferably 90% by mass or more, and more preferably 95% by mass or more.

Among particles mainly composed of EVA, particles having a particle diameter in the range of 1 to 30 μm are the heat-adhesive particles (I).
The inclusion of the heat-adhesive particles (I) as a main component means that the proportion of the heat-adhesive particles (I) in the dry solid content of the heat-adhesive particle layer is 50% by mass or more. The proportion of the heat-adhesive particles (I) in the dry solid content of the heat-adhesive particle layer is preferably 60 to 99% by mass, and more preferably 75 to 95% by mass.
By setting the ratio of the heat-adhesive particles (I) to 50% by mass or more, and more preferably a preferable lower limit value or more, it becomes easy to maintain the air permeability and moisture permeability of the heat-adhesive particle layer. Moreover, it can be set as the filter which has favorable adhesiveness with the other party member by making the ratio of thermoadhesive particle | grains (I) below into a preferable upper limit, and using an adhesion aid etc. together.

The heat-adhesive particles (I) are preferably the following heat-adhesive particles (Ia), and more preferably the following heat-adhesive particles (Ib).
Thermal adhesive particles (Ia): particles having an ethylene vinyl acetate copolymer as a main component and a particle diameter in the range of 1 to 20 μm.
Thermal adhesive particles (Ib): particles having an ethylene vinyl acetate copolymer as a main component and a particle diameter in the range of 1 to 15 μm.

The proportion of the heat-adhesive particles (Ia) in the dry solid content of the heat-adhesive particle layer is preferably 50% by mass or more, more preferably 60 to 99% by mass, and 75 to 95% by mass. Is more preferable.
The proportion of the thermal adhesive particles (Ib) in the dry solid content of the thermal adhesive particle layer is preferably 50% by mass or more, more preferably 60 to 99% by mass, and 75 to 95% by mass. Is more preferable.

<Thermal adhesive resin>
Thermal adhesive resin (II), which is a thermal adhesive resin other than thermal adhesive particles (I), includes ethylene (meth) acrylic acid copolymer, ethylene-vinyl acetate copolymer, acrylic ester polymer, and polyethylene. It is preferable that the main component is one or more selected from polybutene.

Examples of the heat-adhesive resin (II) include heat-adhesive particles having a particle diameter of less than 1 μm, heat-adhesive particles having a particle diameter of more than 30 μm, and a thin film or amorphous heat present at the interface with the paper substrate. Examples thereof include an adhesive resin and thermal adhesive particles that do not contain EVA as a main component.
If many heat-adhesive particles having a particle diameter of more than 30 μm are contained, it may be difficult to apply the heat-adhesive particle layer coating liquid to the paper substrate. For this reason, the number of heat-adhesive particles exceeding 30 μm is preferably small, and more preferably 0.
Further, if a large amount of heat-adhesive particles not containing EVA as a main component is contained, there is a possibility that sufficient adhesiveness may not be obtained. Therefore, it is preferable that the number of heat-adhesive particles not containing EVA as a main component is small. More preferred.

That is, the heat-adhesive resin (II) is one or both of a heat-adhesive particle having a particle diameter of less than 1 μm and a thin-film or amorphous heat-adhesive resin present at the interface with the paper substrate. The heat-adhesive resin (IIa) is preferable.
The proportion of the heat-adhesive resin (IIa) in the dry solid content of the heat-adhesive particle layer is preferably 2.5 to 25.0 mass%, more preferably 5.0 to 20.0 mass%. Preferably, it is 5.0-15.0 mass%.
By setting the ratio of the heat-adhesive resin (IIa) to a preferable lower limit value or more, it is possible to strongly heat-bond with the counterpart member. Moreover, it becomes easy to maintain the air permeability and moisture permeability of a thermobonding particle layer by making the ratio of thermoadhesive resin (IIa) below a preferable upper limit.

<Adhesion aid>
The thermal adhesion particle layer is one or more types of adhesion assistant selected from acid-modified polyolefin resin, chlorinated polyolefin resin, chlorinated ethylene-vinyl acetate copolymer resin, acid-modified chlorinated polyolefin resin, and acrylic-modified chlorinated polyolefin resin. An agent (hereinafter sometimes referred to as “adhesion aid (III)”). Among the adhesion assistants (III), acid-modified chlorinated polyolefin resins are preferable.
Adhesion aid (III) can remarkably improve the adhesion of the paper substrate to the mating member. A particularly remarkable effect is obtained when a member made of a polyolefin-based material, particularly a polypropylene-based material, is used as the counterpart member.

  When the adhesion assistant (III) is added to the coating liquid containing the heat-adhesive particles (I), after drying the coating liquid, at least a part of the surface of the heat-adhesive particles (I) is caused by the adhesion assistant (III) It will be covered. The adhesion aid (III) present on the surface of the heat-adhesive particles (I) is a particle of the heat-adhesive particles (I) when the heat-adhesive filter is thermocompression bonded to the other-member member. It is thought to help to get in between. As a result, it is considered that the melt of the counterpart member penetrates deeper into the thermal bonding particle layer, and the adhesive strength is increased.

The proportion of the adhesion aid (III) in the dry solid content of the thermal bonding particle layer is preferably 1 to 35% by mass, more preferably 5.0 to 20% by mass, and 5.0 to 15%. More preferably, it is mass%.
By making the ratio of the adhesion auxiliary agent (III) equal to or more than the preferable lower limit value, an effect of improving the adhesive strength can be expected. Moreover, it becomes easy to maintain the air permeability and moisture permeability of a thermal-adhesion particle layer by making the ratio of adhesion adjuvant (III) below a preferable upper limit.

<Other ingredients>
The thermal bonding particle layer may contain other components as long as the effects of the present invention are not impaired. Examples of other components include starch, modified starch, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride Water-soluble polymer compounds such as acid copolymer salts, aqueous polymer compounds such as styrene-butadiene copolymer emulsions, urethane resins, urea resins, mold release agents, antifoaming agents, dispersants, wetting agents, colored dyes, Examples include colored pigments and white pigments. Any one of these may be used alone, or two or more may be used in combination.

(Adhesive strength)
When the heat-adhesive filter is thermally bonded to the mating member and then peeled off, the two may be broken and peeled in the heat-bonding particle layer, or the paper substrate may be broken and peeled.
In shipping and distribution inspection of products to which a heat-adhesive filter is bonded, if a product that breaks in the heat-adhesive particle layer and peels off the heat-adhesive filter is peeled off due to poor adhesion during manufacturing It is difficult to determine whether it has been peeled off due to an accident during transportation. On the other hand, if there is a break in the paper substrate, it is clear that poor adhesion is not the cause.
From such a product security problem, the strength of the thermal adhesive particle layer is preferably higher than the strength of the paper base material, and after thermally bonding the counterpart member, the thermal adhesive filter was peeled off from the counterpart member. It is sometimes preferred that the paper substrate breaks.

(Mechanism of action)
The heat-adhesive particles (I) present in the heat-adhesive particle layer of the present invention are bonded to each other at the particle interface while maintaining the particle shape to some extent, and there are many voids between the particles. Yes. Therefore, even if the thermal adhesion particle layer is formed on the entire surface of the paper substrate, air permeability and moisture permeability can be obtained.
The thermoadhesive particles (I) are crushed when the thermoadhesive filter is thermocompression bonded to the mating member, and the gaps between the thermoadhesive particles (I) disappear. Therefore, a gap is generated in the thermocompression bonding portion, and there is no fear of so-called side leakage or the like.
Moreover, although the reason is not certain, the heat-adhesive particles (I) mainly composed of EVA have a strong adhesive force.
In addition, since the base material is paper, it is possible to easily achieve both bactericidal properties, air permeability and moisture permeability, and the production cost is low.

[Method for producing thermal adhesive filter]
A thermal adhesive filter is obtained by applying and drying a thermal adhesive particle layer coating solution containing thermal adhesive particles (I) on at least one surface of a gas-permeable paper substrate to form a thermal adhesive particle layer. It is done.

(Coating liquid for thermal bonding particle layer)
The proportion of the heat-adhesive particles (I) in the dry solid content of the coating liquid for the heat-adhesive particle layer is 50% by mass or more, preferably 60-99% by mass, and 75-95% by mass. More preferred.
The heat-adhesive particles (I) having a particle size of 1 μm or more remain in the heat-adhesive particle layer as they are even after the coating and drying process. Therefore, by setting it as the above ratio, the ratio of the heat-adhesive particles (I) in the dry solid content of the heat-adhesive particle layer is also substantially the above-mentioned ratio.

  The thermal adhesive particle layer coating liquid may contain a thermal adhesive resin (II). The heat-adhesive resin (II) is preferably a heat-adhesive resin (IIa). The preferable ratio of the heat-adhesive resin (IIa) in the dry solid content of the coating liquid for the heat-adhesive particle layer is the same as the preferable ratio of the heat-adhesive resin (IIa) in the dry solid content of the heat-adhesive particle layer.

  It is preferable that the thermal adhesive particle layer coating liquid does not contain or contains a small amount of thermal adhesive particles having a particle diameter exceeding 30 μm as the thermal adhesive resin (II). The proportion of the heat-adhesive particles having a particle diameter exceeding 30 μm in the dry solid content of the coating liquid for the heat-adhesive particle layer is preferably 10% by mass or less, more preferably 5% by mass or less, and 0% by mass. More preferably, it is% or less.

In order to accurately determine the ratio of the heat-adhesive particles having a particle diameter in the range of 1 to 30 μm and the ratio of the heat-adhesive particles having a particle diameter exceeding 30 μm in the dry solid content of the coating liquid for the heat-adhesive particle layer, Coulter Using a counter, the particle size distribution of the heat-adhesive particle raw material obtained by the pore electrical resistance method and the heat-adhesive particle raw material (dry solid) in the total raw material (dry solid content) used for preparing the coating liquid for the heat-adhesive particle layer Min)). As the coulter counter, for example, a multisizer manufactured by Coulter, Inc. can be used.
When using a heat-adhesive particle raw material with a narrow particle distribution and almost 100% of the particles having a particle diameter in the range of 1 to 30 μm, all the raw materials for the heat-adhesive particle layer coating liquid (dried solid The ratio of the heat-adhesive particles in the range of the particle diameter of 1 to 30 μm may be determined from the blending ratio of the heat-adhesive particle raw material (dry solid content) in (min).

As the heat-adhesive particle material, it is preferable to use a particle dispersion liquid having an average particle diameter of 0.5 to 30 μm, more preferably a particle dispersion liquid of 1 to 20 μm, and 1 to 15 μm. More preferably, a dispersion of particles is used.
The average particle diameter is a volume average particle diameter determined by a pore electrical resistance method using a Coulter counter (for example, Multisizer manufactured by Coulter).
Water is preferable as the dispersion of the heat-adhesive particle material.

(Coating drying)
Examples of a method for applying the coating liquid for the thermal bonding particle layer include coating by a coater or coating by a printing machine.
As the coater, a pre-measuring method such as a gravure coater, curtain coater, die coater, gate roll coater, shim sizer, etc. is preferable, and it is difficult for selective adsorption of coating liquid components to the paper substrate to be coated. A coater and a die coater are more preferable.
Although it is a post-lightweight system, the bar coater can be used because the pressing of the coating liquid for the thermal bonding particle layer into the paper substrate is not strong.

Drying after the application of the coating liquid for the thermal bonding particle layer is performed under conditions that maintain the particle state after drying. The drying temperature is determined in consideration of the melting point of the thermoadhesive particles. However, since the temperature reached on the coated surface varies depending on the drying time, an appropriate drying temperature cannot be defined unconditionally.
The melting point of the thermal bonding particles varies depending on the ratio of ethylene units to vinyl acetate units in the resin constituting the particles.

[Bacteria bed bag]
A bag for bacteria beds can be obtained by thermocompression bonding the thermoadhesive filter of the present invention to a bag body in which vent holes are formed so as to cover the vent holes.
The material of the bag body is preferably a polyolefin material such as polyethylene or polypropylene. Polypropylene is particularly preferable because of its high transparency and easy observation inside the bag. The vent is preferably provided at a position facing the space above the medium so that the heat-adhesive filter does not touch the medium.

Since the thermoadhesive filter of the present invention is thermocompression-bonded around the vent hole, the heat-adhesive filter is cut out to be larger than the vent hole by the amount that can secure the thermocompression-bonding width. The shape of the filter may be, for example, a square having a size that can cover the vent hole even if the vent hole or the seal shape is circular. Although there is no limitation in particular in the thermocompression bonding width, 1-10 mm is preferable, 1-5 mm is more preferable, and 1-3 mm is further more preferable.
The thermocompression bonding is performed at a temperature equal to or higher than the melting point of the thermoadhesive particles (I), the thermoadhesive resin (II), and the counterpart member. By thermocompression bonding at a temperature equal to or higher than the melting point, the paper substrate and the mating member can be firmly bonded, and the heat-adhesive particles (I) are crushed and formed between the heat-adhesive particles (I). Since there is no gap, the paper substrate and the counterpart member can be bonded without gap.
Specifically, the pressure bonding is preferably performed at 100 to 260 ° C, more preferably performed at 120 to 230 ° C, and further preferably performed at 150 to 210 ° C.
The pressure and time at the time of pressure bonding are appropriately adjusted.

[Other uses of thermal adhesive filters]
The heat-adhesive filter of the present invention can be used as a filter for vents of fungus bed bags, or used for chemical packaging materials such as oxygen scavengers, desiccants, deodorants, insect repellents, and VOC adsorbents. Good.
When the heat-adhesive filter of the present invention has a heat-adhesive particle layer on both sides of a paper substrate, it can be heat-bonded while being sandwiched between a pair of mating members.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the following Example. In addition,% is the mass% unless there is particular notice. The “mass part” of the raw material is the mass including the dispersion medium.

[Example 1]
(Manufacture of paper substrate)
A pulp slurry of 100 parts by mass of hardwood kraft pulp (LBKP) was beaten with a refiner to obtain a pulp slurry having a Canadian standard freeness of 400 mL measured according to JIS P 8121-2: 2012. Next, an alkenyl succinic anhydride sizing agent (Fibran) dispersed in cationized starch (Pillar 3YK, manufactured by Pillar Starch Co., Ltd.) in an amount of 0.5% sulfuric acid band with respect to the absolutely dry pulp mass as an internal additive chemical in the pulp slurry. 81K, manufactured by National Starch Co., Ltd.) 0.05%, amphoteric polyacrylamide resin paper strength enhancer (Polystron (registered trademark) OFT-3, Arakawa Chemical Industries, Ltd.) 0.7%, epichlorohydrin-based wet paper strength enhancer (Arafix (registered trademark) 255, manufactured by Arakawa Chemical Industries, Ltd.) 0.4% was added to obtain a papermaking raw material. The paper raw material is made with a long paper machine, a paper having a basis weight of 60 g / m ² , a density of 0.7 g / cm ³ , and an Oken type air permeability of 9 seconds measured according to JIS P 8117: 2009. A substrate was obtained.

(Manufacture of thermal adhesive filter)
Thermally adhesive particles mainly composed of an ethylene-vinyl acetate copolymer (Chemipearl (registered trademark) V-200, average particle size of 7 μm, most of the particles are in the range of 1 to 15 μm, and the entire amount is the present invention. 22.5 parts by weight of a 40% aqueous dispersion of Mitsui Chemical Co., Ltd., an ethylene-vinyl acetate copolymer resin emulsion (EA-H700, manufactured by Toyo Ink Co., Ltd.) 2.0 parts by mass of 50% aqueous dispersion, 3.2 parts by mass of 31% aqueous dispersion of acid-modified polypropylene resin emulsion (Hardlen (registered trademark) NZ-1022, manufactured by Toyobo Co., Ltd.) as an adhesion aid, and 27.3 water The thermal adhesive particle layer coating solution obtained by mixing and stirring mass parts was applied using a Mayer bar so that the coating amount after drying was 6 g / m ^2, and dried for 1 minute with a 105 ° C. dryer. Thermal adhesive To obtain a filter. The ratio of the thermal adhesive particles (I) in the dry solid content of the thermal adhesive particle layer calculated from the raw material formulation is 81.9%.
When the surface of the thermal adhesive particle layer of the obtained thermal adhesive filter was observed with an electron microscope, particulate thermal adhesive particles could be confirmed.

[Example 2]
In the production of the heat-adhesive filter of Example 1, no adhesion aid was used, and the amount of ethylene-vinyl acetate copolymer resin emulsion (EA-H700, manufactured by Toyo Ink Co., Ltd.) 50% aqueous dispersion was used. A heat-adhesive filter was obtained in the same manner as in Example 1 except that the content was 0.0 parts by mass. The ratio of the thermal adhesive particles (I) in the dry solid content of the thermal adhesive particle layer calculated from the raw material formulation is 81.8%.
When the surface of the thermal adhesive particle layer of the obtained thermal adhesive filter was observed with an electron microscope, particulate thermal adhesive particles could be confirmed.

[Comparative Example 1]
In the production of the heat-adhesive filter of Example 1, in place of the heat-adhesive particles mainly composed of ethylene-vinyl acetate copolymer, heat-adhesive particles mainly composed of low molecular weight polyethylene (Chemical W310, average particles) 40% aqueous dispersion of 9.5 μm in diameter, most of the particles are in the range of 1 to 15 μm in diameter, and the total amount can be regarded as the thermal adhesive particles (I) in the present invention (Mitsui Chemicals). A heat-adhesive filter was obtained in the same manner as in Example 1 except that 5 parts by mass was used. The ratio of the thermal adhesive particles (I) in the dry solid content of the thermal adhesive particle layer calculated from the raw material formulation is 81.9%.
When the surface of the thermal adhesive particle layer of the obtained thermal adhesive filter was observed with an electron microscope, particulate thermal adhesive particles could be confirmed.

[Evaluation]
The following evaluation was performed on the thermal adhesive filters obtained in the above examples and comparative examples. The results are shown in Table 1.
(1) Air permeability The Oken type air permeability of the heat-adhesive filter was measured according to JIS P 8117: 2009.

(2) Adhesive strength evaluation 1 after thermal bonding processing
A polypropylene film having a film thickness of 50 μm is stacked on the heat-adhesive filter layer side of the heat-adhesive filter, and heated from the paper substrate side of the heat-adhesive filter using a heat press tester. It was peeled off after heat bonding under conditions of 0.5 MPa and a press time of 1 second. The state of the peeled surface was observed and evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: The paper base material is destroyed and a part of the paper base material remains on the polypropylene film.
○: The paper base material and the polypropylene film adhered relatively firmly, but the paper base material was peeled off without breaking the material.
X: It did not adhere | attach. Or the adhesive strength was weak.

(3) Adhesive strength evaluation 2 after thermal bonding
The heat-adhesive filter layer is laminated with the heat-adhesive particle layer side and a 50 μm-thick high-density polyethylene film and heated from the paper substrate side of the heat-adhesive filter using a hot press tester. After heat bonding under conditions of a pressure of 0.5 MPa and a press time of 1 second, the film was peeled off. The state of the peeled surface was observed and evaluated according to the following evaluation criteria.
(Evaluation criteria)
(Double-circle): A paper base material is destroyed and a part of paper base material remains in a high density polyethylene film.
○: The paper base material and the high-density polyethylene film adhered relatively firmly, but the paper base material was peeled off without breaking the material.
X: It did not adhere | attach. Or the adhesive strength was weak.

(4) Antibacterial property test The obtained heat seal sheet is included in the Japan Medical Equipment Manufacturers Association Disposable Medical Device Packaging Material Voluntary Standard (Sterilized Medical Device Packaging Guidelines (Ver.1.0) issued by the Japan Medical Device Industry Federation). 14 to 15), the bacteriostatic test was performed by the method according to the following evaluation criteria.
○: No visible colonies were observed.
X: Visible colonies are recognized.

  As shown in Table 1, the heat-adhesive filters of Examples 1 and 2 were able to achieve both antibacterial properties, air permeability, and moisture permeability, and had strong adhesive strength. In particular, Example 1 using an adhesion assistant had such a strong adhesive force that the paper substrate was destroyed when it was peeled off.

Claims (8)

An air permeable paper base material, and a thermal adhesion particle layer provided on at least one surface of the paper base material,
The thermal adhesive particle layer is composed mainly of the following thermal adhesive particles (I).
Thermal adhesive particles (I): particles having an ethylene vinyl acetate copolymer as a main component and a particle diameter in the range of 1 to 30 μm.   The thermal adhesive filter according to claim 1, wherein a freeness defined by JIS P 8121-2: 2012 of the pulp constituting the paper substrate is 300 to 700 mL. Thermoadhesive filter according to claim 1 or 2 basis weight of the paper substrate is 15~200g / ^{m 2.}   The thermal adhesive filter according to any one of claims 1 to 3, wherein the paper substrate contains a wet paper strength enhancer. The thermal adhesive filter according to any one of claims 1 to 4, wherein a dry coating amount of the thermal adhesive particle layer is 1 to ²⁰ g / m2.   The thermal adhesion particle layer is further one or more selected from an acid-modified polyolefin resin, a chlorinated polyolefin resin, a chlorinated ethylene-vinyl acetate copolymer resin, an acid-modified chlorinated polyolefin resin, and an acrylic-modified chlorinated polyolefin resin. The heat-adhesive filter as described in any one of Claims 1-5 containing the adhesion adjuvant of this.   The thermal adhesive particle layer further includes a thermal adhesive resin other than the thermal adhesive particle (I), and the thermal adhesive resin other than the thermal adhesive particle (I) is an ethylene (meth) acrylic acid copolymer. The heat-adhesive filter as described in any one of Claims 1-6 which has as a main component 1 or more types chosen from a coalescence, an ethylene-vinyl acetate copolymer, an acrylate polymer, polyethylene, and polybutene. A method for producing a heat-adhesive filter in which a heat-adhesive particle layer is formed by applying and drying a coating solution for a heat-adhesive particle layer containing the following heat-adhesive particles (I) on at least one surface of a gas-permeable paper substrate. There,
The method for producing a heat-adhesive filter, wherein the proportion of the heat-adhesive particles (I) in the dry solid content of the coating liquid for the heat-adhesive particle layer is 50% by mass or more.
Thermal adhesive particles (I): particles having an ethylene vinyl acetate copolymer as a main component and a particle diameter in the range of 1 to 30 μm.