JP6581845B2 - Water absorption sheet - Google Patents

Description

  The present invention relates to a water-absorbing sheet that can absorb moisture from fresh fish and meat and remove moisture from vegetables.

  Conventionally, water-absorbing sheets have been used to maintain the freshness by absorbing moisture from fresh fish and meat. The water-absorbing sheet is used on the bottom of a tray for selling fresh fish and meat, and is also used for trays of water-containing fruits and vegetables. Such a water absorbing sheet uses a water absorbing polymer or a porous resin as a water absorbing layer.

  However, since microorganisms are easy to propagate in the moisture exuded from fresh fish and meat, water-absorbing sheets having an antibacterial effect in addition to the water-absorbing effect have been proposed. For example, Patent Document 1 discloses an antibacterial water-absorbing sheet containing a soluble glass powder capable of releasing silver ions. Patent Document 2 discloses an antibacterial water-absorbing sheet containing an alkaline antibacterial agent such as calcium hydroxide. However, these are mainly aimed at suppressing the growth of microorganisms, and although they can be expected to have some effect of preventing spoilage odor, they do not have an excellent deodorizing effect.

In addition, the soluble glass of patent document 1 can expect the deodorizing effect with respect to sulfur type malodor substances, such as hydrogen sulfide and methyl mercaptan, because the emitted silver ion chemisorbs a malodor component. However, since the vitreous deodorant held in the film is a fine powder having a particle size of D ₉₆ = 40 μm or less, the total silver content is small, and the effect depends on the surface exposure. For this reason, it is inevitable that the deodorizing effect of the water-absorbent sheet of Patent Document 1 gradually decreases as the release of silver ions proceeds. In addition, there is no deodorizing effect on malodorous substances such as lower fatty acids.

  Although the alkaline antibacterial agent of Patent Document 2 may also be able to prevent malodor by neutralization reaction with the malodorous component, it is inevitable that the deodorizing effect gradually decreases as the release of the alkali component proceeds. .

Japanese Patent No. 3105290 JP 2012-241296 A

  Therefore, the object of the present invention is to solve the above-mentioned conventional problems, and has a superior deodorizing effect, and deodorizes not only sulfur-based malodorous substances such as hydrogen sulfide and methyl mercaptan but also malodorous substances such as lower fatty acids. It is providing the water absorption sheet | seat provided with the function to do.

The present invention made in order to solve the above-mentioned problems is a water-absorbent sheet comprising a water-absorbing layer and having a glass body deodorant held in a sheet body used for a food tray, and this glassy deodorant Is an alkali-alkaline earth-borosilicate glass containing a copper component and 2-7 mol% R′O (R ′ = Mg, Ca, Sr, Ba), or a copper component and 2-10 mol% R ′ It consists of an alkali-alkaline earth-silicate glass containing O and decomposes malodorous components by the catalytic action of the copper component held in the glass while it is kept in the glass without eluting the copper component. It has a function.

As in claim 2, the content of the vitreous deodorant is preferably 1 to 100 g / m ^2, and as in claim 3, the vitreous deodorant has a D _{96 of} 100 μm or less. A powder is preferred.

  Furthermore, it is preferable that the water absorbing layer contains a water absorbing polymer.

The water-absorbing sheet of the present invention comprises a copper component and an alkali-alkaline earth-borosilicate glass containing 2 to 7 mol% R′O (R ′ = Mg, Ca, Sr, Ba), or a copper component and 2 to 2 mol%. A glassy deodorant comprising alkali-alkaline earth-silicate glass containing 10 mol% R′O is provided with a water absorption layer and held on a sheet body used for a food tray. The malodorous component is decomposed by the catalytic action of the copper component retained in the glass while being retained in the glass without eluting the copper component.

  While various deodorants using soluble glass have been developed, conventionally, a “glass agent showing a deodorizing effect by catalytic action” has not been known. As a result of many years of research, the inventors of the present invention, the copper component contained in the glass of the above composition functions as a catalyst, promotes the decomposition reaction of the sulfur-based malodorous substance, the deodorizing effect of the sulfur-based malodorous substance I found a new finding that "I play".

In the present invention, as described above, since it has a mechanism for promoting the decomposition reaction of the sulfur-based malodorous substance using the copper component contained in the glass as a catalyst, compared to the conventional technology using chemical adsorption and physical adsorption, The deodorizing capacity can be increased, and the deodorizing effect can be exhibited stably over a long period of time. That is, both conventional chemical adsorption and physical adsorption depend on the surface exposure amount of the adsorbent, and the deodorization limit is determined by the exposure amount. However, in the present invention, since the catalytic reaction is used, the exposure amount is small. Even so, a large total deodorizing amount can be obtained. For this reason, if paying attention only to the deodorizing amount, a small amount of the glassy deodorant may be added, but in order to add a deodorizing speed, it is preferable to contain 1 to 100 g / m ² as described above.

  The vitreous deodorant used in the present invention can exhibit an excellent deodorizing effect particularly with respect to methyl mercaptan. That is, this glassy deodorant catalytically oxidatively decomposes methyl mercaptan to produce dimeric dimethyl disulfide. At this time, radicals are generated and oxidatively decomposed. Similarly, similar oxidative decomposition is possible for other gases. This point is also referred to in examples described later. However, the odor that can be deodorized is not limited to sulfur-based odor substances. Specific examples include lower fatty acids, acetic acid known as body odor (sweat, foot odor), isovaleric acid, propionic acid, normal butyric acid, normal valeric acid, and medium chain fatty acid caproic acid Also, enanthic acid and trans-2-nonenal, known as an aging odor, can be deodorized. Generally, those having 2 to 4 carbon atoms are referred to as short-chain fatty acids (lower fatty acids), but in this specification, acetic acid having 1 carbon atom and 5 valeric acids are also treated as lower fatty acids.

The water-absorbent paper having a deodorizing function of the present invention is suitable for use on the bottom of a tray for selling fresh fish and meat as described above, or for a fruit or vegetable tray .

It is typical sectional drawing which shows the use condition of the water absorbing sheet of embodiment. 10 is a graph showing the results of Example E.

Embodiments of the present invention will be described below.
The water-absorbing sheet of the present invention comprises a water-absorbing layer, and a glass body deodorant held on a sheet body used for a food tray . This glassy deodorant is a substance having excellent safety as shown in Example F described later.

  Materials for the water absorption layer include polyacrylic acid / sodium polyacrylate copolymer, starch / acrylic acid copolymer, cellulose / acrylic acid copolymer, polyethylene oxide, polyvinyl alcohol / acrylic acid copolymer, isobutylene / anhydrous Maleic acid copolymers are typical, but synthetic polymer systems are polyacrylates, polysulfonates, maleic anhydrides, polyacrylamides, polyvinyl alcohols, polyethylene oxides, natural products Examples include polyaspartate, polyglutamate, polyalginate, starch, and cellulose. In addition, polyvinyl alcohol and urethane used as a water absorbing sponge may be used.

  The glassy deodorant may be supported (dispersed or attached in the case of 100% nonwoven fabric) on the water absorption layer portion, or may be attached to the nonwoven fabric covering the water absorption layer portion. Or you may mix | blend or attach to the sheet | seat part which prevents a water leak. Needless to say, the sheet may not be a sheet having all of the above structures, but may be a sheet having only an absorbent layer. For those having pulp paper as the sheet body, a vitreous deodorant may be attached to the pulp paper. Note that zeolite or activated carbon known as an absorbent can be used together with a glassy deodorant.

The vitreous deodorant is composed of an alkali-alkaline earth-borosilicate glass containing a copper component or an alkali-alkali earth-silicate glass containing a copper component, and is a powder having a D _{96 of} 100 μm or less. It is desirable. Here, D ₉₆ means a particle size at which the integral value when the particle size distribution measurement is performed and the cumulative distribution is 96%. More preferred particle size is _{D 96} = 40 [mu] m or less. If D ₉₆ exceeds 100μm decreases the specific surface area of the vitreous deodorant catalytic effect is reduced. When the particle size is less than 1 μm, the efficiency of pulverizing and classifying glass is extremely lowered, which is not preferable in production. A particle size of about 1 to 25 μm is practical, but about 40 μm is easy to handle when attached to a nonwoven fabric. Such a vitreous deodorant can be produced by a method in which the raw material for preparation is melted and rapidly cooled to obtain a pre-molded product, and then pulverized. For the pulverization, a generally known pulverizer (for example, a ball mill, a bead mill, a jet mill, a CF mill, etc.) can be used, and it may be dry or wet.

The amount of vitreous deodorant is about 1 to 100 g / ^{m 2} is preferred. If the amount is less than this, the deodorizing effect becomes insufficient, and even if the amount is larger than this, an increase in the deodorizing effect commensurate with the increase in cost is not recognized.

  As shown in FIG. 1, the water absorbent sheet of the present invention can be used by laying on the bottom of a tray 1, for example. A glassy deodorant 3 is held inside or on the surface of the water absorbent sheet main body 2. However, as described above, the water absorbent sheet of the present invention can be used for various applications. Hereinafter, the composition of the vitreous deodorant will be described in detail.

(Alkali-alkaline earth-borosilicate glass)
The alkali-alkaline earth-borosilicate glass containing the above-described copper component is SiO ₂ : 46 to 70 mol%, B ₂ O ₃ + R ₂ O (R: alkali metal): 15 to 50 mol%, R′O. (R': alkaline earth metal): 2 to 7 _{mol%, Al 2 O 3: 0~6} %, CuO: 0.01~23 a glass containing mol%. _Here, B ₂ O 3: _{5~20 mol%,} R 2 O: can be 10 to 30 mol%.

A preferred composition of this vitreous deodorant _3, SiO 2: 51~63 _{mol%, B 2 O 3 + R} 2 O: 21~39 mol%, R'O: 2 to 7 _mol%, Al _{2 O} 3: 0 to 5.5%, CuO: 1 to 13 mol%. _Here, B ₂ O 3: _{8~17 mol%,} R 2 O: can be 13 to 22 mol%.

The most preferred composition of this vitreous deodorant _3, SiO 2: 53-62 _{mol%, B} 2 O 3: _{10~17 mol%,} R 2 O: _13~19 mol%, R'O: 3~ 6 _{mol%, Al 2 O 3: 0~4.5} %, CuO: 4~13 are mole%. Below, each glass composition is demonstrated in detail.

_(SiO 2)
SiO ₂ is a main component that forms the structural skeleton of glass, and its content is 46 to 70 mol%, preferably 51 to 63 mol%, and more preferably 53 to 62 mol%. If it is less than 46 mol%, the chemical durability of the glass becomes insufficient, and the glass tends to devitrify, which is not preferable. Furthermore, if it is less than 46 mol%, the water resistance of the glass becomes insufficient, and copper ions are more likely to elute in the presence of moisture (including moisture in the atmosphere). Since the deodorizing effect by the sulfurization reaction which occurs by this becomes strong, it is not preferable. If it exceeds 70 mol%, the melting point increases, which makes glass melting difficult and also causes an increase in viscosity.

(B ₂ O ₃ )
B ₂ O ₃ is a component that improves the solubility and clarity of the glass, and in a specific composition, it also becomes a component that forms the structural skeleton of the glass. B ₂ O ₃ greatly affects the stability of the glass depending on its content, and in the present invention, the meaning as a flux of glass is large. Its _content, in consideration of the volatilization amount of B 2 _{O 3,} 5 to 20 mol%, preferably 8 to 17 mol%, further preferably 10 to 17 mol%. When it exceeds 20 mol%, B ₂ O ₃ is not preferred because it tends to volatilize in the melting process and the composition control becomes difficult.

(R ₂ O)
R ₂ O (R = Li, Na, K) breaks the bond between Si and O in the glass structure skeleton to form non-crosslinked oxygen, resulting in a decrease in glass viscosity, moldability and solubility. And a flux similar to B ₂ O ₃ . The content of one or more of R ₂ O is 10 to 30 mol% in total, preferably 13 to 22 mol%, more preferably 13 to 19 mol%, considering the content ratio with multiple components. And When it exceeds 30 mol%, the chemical durability of the glass becomes insufficient. Specifically, a whitening phenomenon called bloom is caused by a reaction between the glass agent and moisture in the atmosphere. The occurrence of bloom is undesirable because it reduces the contact area with malodorous gas.

(B ₂ O ₃ + R ₂ O)
As mentioned above, both B ₂ O ₃ and R ₂ O are used as fluxing agents. The range in which the total content of B ₂ O ₃ and R ₂ O is 15 to 50 mol%, preferably 21 to 39 mol%, is a region that safely exhibits the deodorizing effect. If it is less than 15 mol%, the meltability of the glass becomes insufficient, and devitrification tends to occur during molding, which is not preferable. If it exceeds 50 mol%, the water resistance of the glass becomes insufficient, and copper ions are likely to elute in the presence of moisture (including moisture in the atmosphere), resulting in ion elution rather than deodorizing effect due to catalysis. Since the deodorizing effect by a sulfurization reaction becomes strong, it is not preferable. On the other hand, if it exceeds 50 mol%, phase separation is likely to occur during melting, and the deodorizing effect of the glass agent becomes insufficient accordingly.

(R'O)
R′O (R ′ = Mg, Ca, Sr, Ba) is a component that improves the chemical durability of the glass. The content of R′O (R ′ = Mg, Ca, Sr, Ba) is 1 to 2 mol%, more preferably 3 to 6 mol%, in total, with one or more of R′O (R ′ = Mg, Ca, Sr, Ba). More than 10 mol% and with the viscosity at the time of melting increases, undesirable because the glass tends to be devitrified.

(Al ₂ O ₃ )
Al ₂ O ₃ is a component that improves the chemical durability of the glass and affects the crystal structure stability. Further, Al ₂ O ₃ functions to suppress the phase separation of the glass and increase the homogeneity of the glass agent. Since the viscosity and the addition may affect the redox state of copper ions in the glass, its content is 6 mol% or less, preferably 5.5 mol% or less, most preferably 4 .5 mol% or less.

(CuO)
CuO functions as a catalyst, accelerates the decomposition reaction of the sulfurous malodorous substance, and exhibits the deodorizing effect of the sulfurous malodorous substance. The content is 0.01 to 23 mol%, preferably 1 to 13 mol%, more preferably 4 to 13 mol%. If it exceeds 23 mol%, undissolved material tends to remain, and metal copper tends to precipitate during rapid cooling or processing, which is not preferable. Since the glass is discolored with the deposition of metallic copper, it is not suitable for applications where discoloration of the glass is a problem. Moreover, when it precipitates as metallic copper, poisoning will advance. On the other hand, if CuO is included as a glass component, poisoning does not proceed easily, and the catalytic function can be stably exhibited over a long period of time.

(Other trace components)
In addition to the above components, ZnO, SrO, BaO, TiO ₂ , ZrO ₂ , Nb ₂ O ₅ , P ₂ O ₅ , Cs ₂ O, Rb ₂ O, TeO ₂ , BeO, GeO ₂ , Bi ₂ can be used as trace components. O ₃ , La ₂ O ₃ , Y ₂ O ₃ , WO ₃ , MoO ₃ , Fe ₂ O ₃ or the like can also be included. Furthermore, F, Cl, SO ₃ , Sb ₂ O ₃ , SnO ₂ , Ce, or the like may be added as a clarifier.

(Alkali-alkaline earth-silicate glass)
In the present invention, an alkali-alkaline earth-silicate glass containing a copper component can also be used as the vitreous deodorant 3. This _glass, SiO 2: 50-70 _mol%, R 2 O: _10~33 mol%, R'O: 2 to 10 _{mol%, Al 2 O 3: 0~6} %, CuO: 0.01~23 It is a glass containing mol%.

A preferred composition of the vitreous deodorant _3, SiO 2: 55 to 70 _mol%, R 2 O: _12~24 mol%, R'O: 2 to 10 _{mol%, Al 2 O 3: 0~5} . 5%, CuO: 1 to 20 mol%. The most preferred composition of this vitreous deodorant _3, SiO 2: 55 to 65 _mol%, R 2 O: _12~20 mol%, R'O: 3 to 7 _mol%, Al ₂ O 3: _0~ 5%, CuO: 4 to 13 mol%.

Unlike the alkali-alkaline earth-borosilicate glass described above, the alkali-alkaline earth-silicate glass does not contain B ₂ O ₃ , so the numerical range of the composition is slightly changed. Is the same as alkali-alkaline earth-borosilicate glass.

  The content of the glassy deodorant 3 in the water absorbent sheet is preferably 0.1 to 15% by mass. If it is less than this range, the deodorizing effect is insufficient, and conversely, the cost exceeds 15% by mass. A preferable content rate is 0.1-10 mass%. In the present invention, since the vitreous deodorant exhibits a deodorizing function due to a catalytic effect, the deodorizing amount does not depend on the exposure amount of the vitreous deodorant. For this reason, in the long term, a small amount may be exposed on the surface, and even if the content exceeds 15%, an increase in deodorizing amount cannot be expected.

  The water-absorbing sheet of the present invention has a function of decomposing malodorous components by the catalytic action of the copper component held in the glass of the vitreous deodorant. Unlike the soluble glass, the copper component decomposes the malodorous component by the catalytic action while being retained in the glass, so that the deodorizing effect is maintained over a long period of time and the durability is excellent. Further, since the soluble glass is an acidic glass, it does not have a deodorizing effect on lower fatty acids that are acidic malodors, but the vitreous deodorant in the present invention has a deodorizing effect on malodorous substances such as lower fatty acids and body odor components. .

  In the above-described embodiment, the vitreous deodorant is used alone, but it can also be used in combination with an inorganic deodorant such as general-purpose silica gel, zeolite, activated carbon, clay mineral, photocatalyst (titanium dioxide). Moreover, it can also be used with the phosphate glass containing the silver of patent document 1. Such combined use makes it possible to aim at effects such as speeding up the deodorization speed, expanding target gas, and reducing costs.

  The water absorbent sheet of the present invention can be used for any purpose called a drip sheet, a freshness maintaining sheet, a moisture adjusting sheet, a functional water absorbent sheet, or the like. For other uses, it is suitable as an insole for storing vegetables and pickles. This is because onions and pickles generate sulfur odor. In this case, since it is stored in the refrigerator for several days, the sustainability of the deodorizing effect is also required, and the advantages of the water absorbent sheet of the present invention are exhibited. In addition, it can be used for sanitary products, disposable diapers, pet sheets, moisture separation sheets, anti-condensation sheets, etc., and is also effective for deodorizing indoors.

  Examples of the present invention are shown below. In the table, n.d. means not detected.

Glass raw materials were prepared so as to have the composition shown in Table 1, and melted, molded, and pulverized by a melt quenching method to produce a glassy deodorant. The obtained glassy deodorant was held on the water absorbent sheet under the conditions shown in Table 2. Using this water absorbent sheet, a deodorizing effect confirmation test was conducted.
The water-absorbing sheet has a water-absorbing layer made of a granular polyacrylate-based highly water-absorbing polymer, the water-permeable layer is a rayon nonwoven fabric, the non-water-permeable layer is made of a polyethylene film, and the end portion thereof is 10 cm × 10 cm. Sealed. Dispersion in the water-absorbing layer and loading on the water-passing layer were studied. Moreover, the water absorption sheet | seat which made the cotton pulp layer interpose on the upper and lower sides of a water absorption layer was also produced, and carrying | support was investigated to the pulp layer. The water-passing layer and the pulp layer were loaded by spraying with a urethane emulsion binder.

(Example A: Confirmation of deodorizing effect)
The water-absorbing sheets of Experimental Examples 1 to 21 in Table 2 were enclosed in a 1 L Tedlar bag together with a malodor component, and the malodor concentration in the bag with the elapsed time was measured at room temperature. Hydrogen sulfide and methyl mercaptan were measured with a gas chromatograph, and acetic acid and propionic acid were measured with a gas detector tube. As a comparison, a glassy deodorant composed of the soluble glasses 1 to 3 shown in Table 3 was produced and pulverized to D ₉₆ = 25 μm or less, and the water absorption layer had a content of 1 g / m ² as in the experimental example. As distributed. In addition, Experimental example 3 using the glass which does not contain a copper component corresponds to a blank. As a result, as shown in Table 4, it was confirmed that any offensive odors had a deodorizing effect except for the blank. It was also confirmed that the soluble glass has no deodorizing effect on lower fatty acids.

(Example B: Sustainability to soluble glass)
The water-absorbing sheets of Experimental Examples 1, 2, 5, and 6 in Table 2 were sealed in a 1 L Tedlar bag together with malodor components, and the malodor concentration in the bag was measured with a gas chromatograph at room temperature. For comparison, a glassy deodorant composed of the soluble glasses 2 to 4 shown in Table 3 was produced and pulverized to D ₉₆ = 25 μm or less, and the water absorption layer had a content of 1 g / m ² as in the experimental example. As distributed. As a result, as shown in Table 5, it was confirmed that the water-absorbing sheet containing the soluble glass reached the deodorizing limit although the deodorizing speed was high because of the chemical adsorption reaction, whereas the water-absorbing sheet of the present invention was confirmed. It was confirmed that the sheet showed a deodorizing effect by catalytic action and was excellent in total deodorizing amount. However, the glass changes continuously depending on the composition, and the effect also changes continuously from the catalytic reaction to the adsorption reaction of the soluble glass. Since Experimental Example 5 had a composition with reduced durability (because it was a composition approaching soluble glass), it was confirmed that the tendency of the adsorption reaction was the same as that of soluble glass and reached the deodorization limit.
In addition, after adjusting the sample, the light was blocked and stored, and the above deodorization test was performed in a state where 1 ml of distilled water was contained. Thus, it was confirmed that the deodorizing effect was exhibited even in the presence of moisture, and the catalytic effect was exhibited even without light.

(Example C: Basic characteristics and decomposition action of glassy deodorant)
D ₅₀ = 4.2 μm ground glass 1g consisting of composition number 6 in Table 1 and methyl mercaptan were sealed in a 5 L Tedlar bag, and methyl mercaptan and dimethyl disulfide in the bag over time were measured with a gas chromatograph at room temperature. did. Moreover, the same operation was performed as a blank, without a glassy deodorant. In addition, it was confirmed in advance by a gas chromatograph mass spectrometer that the gas components present in the bag were only these two components. As a result, as shown in FIG. 2, it was confirmed that the vitreous deodorant of the present invention has an action of decomposing methyl mercaptan and generating dimethyl disulfide. The basic characteristics of the glassy deodorant are naturally maintained even when kneaded into a film or the like.

(Example D: Basic characteristics of glassy deodorant / radical generation)
D ₅₀ = 0.1 mol·L ⁻¹ phosphate buffer solution of pH = 7.4 with respect to 200 mg of the glass composed of the soluble glass 1 of composition numbers 6 and 9 and table 3 of Table 1 ground to 5.0 μm 200 μL was added. Thereto, 10 μL of 9.2 mol·L ⁻¹ DMPO (manufactured by LABOTEC, LM-2110) was added and shaken. Shake was stopped 10 seconds, 1 minute, and 5 minutes after DMPO addition, and only the solution was collected with a hematocrit tube, and ESR (manufactured by JEOL Ltd., FR-30, X band) measurement was performed. Moreover, the thing except glass was made into the blank. All were performed at room temperature under fluorescent light. This technique corresponds to the spin trap method, which is a general technique for measuring radicals, and spin adducts are generated when DMPO captures radicals. This product (DMPO-OH) was detected by ESR. The unit of the detected value is a peak area value ratio (area single / area manganese, S / M) with respect to the reference material Mn ²⁺ . The results are shown in Table 6. The composition No. 6 glass was confirmed to produce DMPO-OH, whereas the composition No. 9 and the soluble glass 1 only showed a background value as in the blank. It was confirmed that the vitreous deodorant of the present invention has a high possibility of generating radicals.

(Example E: Basic characteristics of glassy deodorant and suppression of catalyst deterioration)
D ₅₀ = 4.2 μm crushed glass of composition number 6 in Table 2 0.1 g and CuO reagent (average particle size 4 μm) 0.1 g each was sealed in a 1 L Tedlar bag at room temperature with time The methyl mercaptan concentration in the bag was measured with a gas chromatograph. The initial concentration of methyl mercaptan was 55 ppm and repeated up to 10 times. Moreover, the same operation was performed without glass as a blank. As a result, as shown in Table 7, the deodorizing effect of the CuO reagent is reduced with repetition. This is a generally known catalyst deterioration (sulfur adsorption) of CuO. On the other hand, it was confirmed that the glass maintained the deodorizing effect and was highly sustainable. Although elucidation of this mechanism remains, it has been confirmed that catalyst degradation is suppressed by vitrification. When the glass surface at this time was analyzed by XPS (manufactured by ULVAC-PHI Co., Ltd., PHI 5000 VersaProbe), as shown in Table 8, it was confirmed that there was certainly no sulfur adsorption after deodorization. The basic characteristics of a glassy deodorant are naturally maintained even when kneaded into a film or the like.

(Example F: Safety of glassy deodorant)
When 100 g of distilled water was immersed in 0.1 g of the glass of composition number 6 in Table 1 pulverized to D ₅₀ = 4.2 μm, and the elution amount after 24 hours at room temperature was measured with an ICP emission spectrometer, The amount of elution was not more than the lower limit of quantification of 0.1 ppm. Moreover, when the weight of the glass before and behind immersion was confirmed, the amount of melt | dissolution was 0.0%. The safety of copper itself is publicly known and certified as a nutritional functional food by the Ministry of Health, Labor and Welfare. An appropriate dose is 0.5 to 5 mg inoculated per day. The quality standard of tap water is 1 ppm, but if 5 L of 1 ppm tap water is consumed, it is equivalent to intake of 5 mg. As described above, it can be seen that it is sufficiently safe when considering elution of a copper component from glass and inoculation of an appropriate amount. The vitreous deodorant used in the present invention is a non-eluting deodorant that exhibits a deodorizing effect without eluting in a normal method of use, so even in countries with strict copper elution regulations, It can be used.

1 tray 2 sheet body 3 glassy deodorant

Claims (4)

A water absorbing sheet comprising a water absorbing layer and having a glassy deodorant held in a sheet body used for food trays,
This glassy deodorant is an alkali-alkaline earth-borosilicate glass containing a copper component and 2-7 mol% R′O (R ′ = Mg, Ca, Sr, Ba), or a copper component and 2- It consists of an alkali-alkaline earth-silicate glass containing 10 mol% R′O, and it is retained in the glass without eluting the copper component, but by the catalytic action of the copper component held in the glass. A water absorbent sheet characterized by having a function of decomposing malodorous components. Water sheet according to claim 1, characterized in that the content of the vitreous deodorant and 1 to 100 g / m ^2. The water-absorbent sheet according to claim 1 or 2, wherein the glassy deodorant is a powder having D ₉₆ = 100 µm or less.   The water absorbing sheet according to any one of claims 1 to 3, wherein the water absorbing layer contains a water absorbing polymer.