Film-like composition and method for producing same

Abstract

To provide techniques of producing a membranous composition containing as a hygroscopic material a metal-organic framework MIL-101(Cr) whose central metal is chromium, for obtaining a membranous composition excellent in applicability while keeping membrane strength and hygroscopic performance excellent.SOLUTION: A membranous composition E containing a hygroscopic material A and configured to be applied onto a substrate X contains as the hygroscopic material A a metal-organic framework MIL-101(Cr) whose central metal is chromium, and contains as an adhesive hardening material B a maleic anhydride-modified polyolefin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a film-like composition containing a moisture absorbent and coated on a substrate, a method for producing the same, and a coating liquid used for producing the film-like composition. [Background technology]

[0002] This type of film-like composition exhibits moisture absorption by containing a moisture-absorbing material. When using such a film-like composition as a coating for a moisture-absorbing part, the higher the moisture absorption amount per unit weight of the coating, the more compact the size of the product containing the composition can be, which contributes to reducing the weight of the product. For example, when used as a coating for a desiccant element of a desiccant-type dehumidifier, the volume occupied by the desiccant element accounts for more than half of the product size, and if the moisture absorption amount of the film-like composition used as the coating for the desiccant element is increased, such a product can be significantly made more compact.

[0003] In recent years, metal organic frameworks (MOFs) have been attracting attention as materials with high adsorption capacity. In particular, a metal organic framework material with chromium as the central metal (hereinafter referred to as MIL-101(Cr)) is known to have more than twice the moisture absorption capacity and high resistance to water degradation compared to materials that have been conventionally used as moisture absorbents (silica gel, zeolite, calcium chloride, polymeric adsorbents, etc.). The present inventors have proposed that when a coating liquid obtained by dispersing a metal-organic framework MIL-101(Cr) having chromium as a central metal as a moisture absorbent in a solvent such as water is applied to a substrate such as polyethylene terephthalate (PET) to produce a film-like composition, an acrylic polymer material is used as an adhesive curing agent (binder) and a urethane polymer material is added as a thickener to ensure the coatability of the coating liquid, thereby achieving good moisture absorption performance while obtaining a coating film having good film strength in which cracking, peeling, etc. are suppressed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-171259 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a film-like composition containing the metal-organic framework MIL-101(Cr) having chromium as the central metal as a moisture absorbent, the addition of a urethane-based polymer material as a thickener is a cause of a decrease in moisture absorption performance, so it is desirable to avoid the addition of such a urethane-based polymer material as much as possible. However, if a urethane-based polymer material is not added, the adhesion of the coating liquid to the substrate decreases, causing a problem of poor coatability. In view of this situation, a main object of the present invention is to provide a technique for obtaining a film-like composition having excellent coatability while maintaining good film strength and moisture absorption performance, when producing a film-like composition containing a metal-organic framework MIL-101(Cr) having chromium as a central metal as a moisture absorbent. [Means for solving the problem]

[0006] The first characteristic configuration of the present invention is a film-like composition containing a moisture absorbent and applied onto a substrate, The moisture absorbent contains a metal organic framework MIL-101(Cr) having chromium as a central metal, The adhesive hardener contains maleic anhydride modified polyolefin. In the present invention, the film-like composition refers to a film-like composition that contains a moisture-absorbing material and is in a state of being applied to a substrate, and the film-like composition itself has moisture absorption properties due to the moisture-absorbing property of the moisture-absorbing material.

[0007] That is, as a result of intensive research, the present inventors have found that when a coating liquid containing a metal-organic framework MIL-101(Cr) having chromium as the central metal as a moisture absorbent is applied to a substrate to produce a film-like composition, if a maleic anhydride-modified polyolefin is used as an adhesive curing agent, a film-like composition with excellent coatability can be obtained without adding a urethane-based polymer material as a thickener, while maintaining good film strength with suppressed cracking, peeling, and the like, and good moisture absorption performance.

[0008] A second characteristic feature of the present invention is that the adhesive curing agent contains an acrylic polymer material.

[0009] According to this configuration, by containing an acrylic polymer material in addition to the maleic anhydride-modified polyolefin as the adhesive curing agent, it is possible to suppress the deterioration of the film strength and moisture absorption performance, while limiting the amount of deterioration of the maleic anhydride-modified polyolefin, and improving the moisture absorption performance.

[0010] A third characteristic configuration of the present invention is that the substrate is any one selected from the group consisting of nonwoven fabric, paper, aluminum, copper, and stainless steel.

[0011] According to this configuration, by selecting the substrate to be coated as any one of nonwoven fabric, paper, aluminum, copper, and stainless steel, it is possible to obtain a film-like composition having good coating film strength without cracking, peeling, etc. Furthermore, if the substrate is any one selected from the group consisting of nonwoven fabric, paper, and copper, the adhesion of the coating liquid to the substrate can be improved.

[0012] A fourth characteristic feature of the present invention is a method for producing a film-like composition having the first to third characteristic features described above, A metal-organic framework MIL-101(Cr) having chromium as a central metal as the moisture absorbent and a maleic anhydride-modified polyolefin as the adhesive curing agent are dispersed in a solvent containing one or more selected from water, acetone, ethanol, and isopropyl alcohol to prepare a coating liquid; The coating liquid is applied onto a substrate and then dried.

[0013] According to this configuration, water, acetone, ethanol, and isopropyl alcohol, which are easy to use, can be used as a solvent for dispersing the metal-organic framework MIL-101(Cr) and the maleic anhydride-modified polyolefin to prepare a coating liquid. The coating liquid thus prepared can be applied to a substrate and dried to easily produce the film-like composition according to the present invention. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram illustrating the film-like composition and the method for producing the same according to the present embodiment. [Diagram 2] Photograph showing the surface state of the film-like composition of Comparative Example 1 [Diagram 3] Photograph showing the surface state of the film-like composition of Example 1 [Figure 4] Photograph showing the surface state of the film-like composition of Example 2 [Diagram 5] Photograph showing the surface state of the film-like composition of Example 3 [Figure 6] Photograph showing the surface state of the film-like composition of Example 4 [Figure 7] Photograph showing the surface state of the film-like composition of Example 5 [Figure 8] Photograph showing the surface state of the film-like composition of Example 6 [Figure 9] Photograph showing the surface state of the film-like composition of Example 7 [Figure 10] Photograph showing the surface state of the film-like composition of Example 8 [Figure 11] Photograph showing the surface state of the film-like composition of Example 9 [Figure 12] Photograph showing the surface state of the film-like composition of Example 10 [Figure 13] Photograph showing the surface state of the film-like composition of Example 11 [Figure 14] Graph showing evaluation results of moisture absorption performance of film-like compositions of Examples 1 to 6 and Comparative Example 1 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the film-like composition E of this embodiment contains a moisture-absorbing material A and is a film-like composition applied onto a substrate X, and is used, for example, as a coating film for a desiccant element of a desiccant-type dehumidifier. The film-like composition E contains, as the moisture absorbent A, a metal organic framework MIL-101(Cr) having chromium as the central metal, and contains, as the adhesive curing material B, a maleic anhydride-modified polyolefin. In the method for producing such a film-like composition E, a metal-organic framework MIL-101(Cr) having chromium as a central metal as a moisture absorbent A and a maleic anhydride modified polyolefin as an adhesive curing material B are dispersed in a solvent C, which is a mixture of one or more selected from water, acetone, ethanol, and isopropyl alcohol, to produce a coating liquid D. Then, the coating liquid D is applied onto a substrate X formed into a flat plate shape, for example, using a coater (coating machine) and dried at a predetermined temperature for a predetermined time, to produce a film-like composition E. The film-like composition E produced in this manner has excellent coatability while maintaining good film strength with reduced cracking, peeling, and the like, and good moisture absorption performance, even without the addition of a urethane-based polymer material as a thickener.

[0016] When preparing coating solution D by dispersing moisture absorbent A and adhesive curing material B in solvent C, the viscosity must be adjusted depending on the type of coater (applicator) used, and the degree of dilution must be set appropriately accordingly. The ratio of the maleic anhydride modified polyolefin as the adhesive curing material B to the metal-organic framework MIL-101(Cr) as the moisture absorbent A is not particularly limited as long as it is within the range of 1 weight % to 40 weight %, but it is preferably within the range of 5 weight % to 35 weight %, and more preferably 10 weight % to 20 weight %.

[0017] By incorporating an acrylic polymer material in addition to the maleic anhydride-modified polyolefin as the adhesive curing material B, it is possible to suppress the decrease in film strength and moisture absorption performance while limiting the amount of decrease in the maleic anhydride-modified polyolefin and improving the moisture absorption performance. The ratio of the acrylic polymer material as the adhesive curing material B to the metal-organic framework MIL-101(Cr) as the moisture absorbent A is not particularly limited as long as it is within the range of 5% by weight to 40% by weight, but is preferably within the range of 15% by weight to 30% by weight, and more preferably 20% by weight to 30% by weight.

[0018] Any material can be used as the substrate X. However, by using any one selected from nonwoven fabric, paper, aluminum, copper, and stainless steel, a film-like composition E having good coating film strength without cracks, peeling, etc. can be obtained.

[0019] [Performance evaluation test] The results of the performance evaluation test of the film-like composition will be described below. First, the configurations of the film-like composition samples of Comparative Example 1 and Examples 1 to 11 used in this evaluation test will be described. In this evaluation test, the metal-organic framework MIL-101(Cr) was synthesized with reference to a non-patent document (G.Ferey et al., SCIENCE, vol. 309, (2005) 2040-2042.). As the maleic anhydride polyolefin, "Hardlen (registered trademark) NZ1015" manufactured by Toyobo Co., Ltd. was used. As the acrylic polymer material, "Bonlon (registered trademark) PS-002" manufactured by Mitsui Chemicals, Inc. was used. In the film-like composition of this embodiment, the maleic anhydride polyolefin and the acrylic polymer material may be different from those exemplified above.

[0020] Comparative Example 1 The film-like composition of Comparative Example 1 was prepared by mixing the metal-organic framework MIL-101(Cr) as the moisture absorbent with only an acrylic polymer material as the adhesive curing agent in a predetermined mixing ratio (see Table 1 below), dispersing the precursor in isopropyl alcohol as a solvent to prepare a coating liquid, applying the coating liquid to a nonwoven fabric as a substrate, and drying at 90°C or higher for 10 minutes or more.

[0021] (Examples 1 to 5) The film-like compositions of Examples 1 to 5 were prepared by mixing the metal-organic framework MIL-101(Cr) as a moisture absorbent with a maleic anhydride-modified polyolefin and an acrylic polymer material as adhesive curing agents in predetermined mixing ratios (see Table 1 below), dispersing the precursor in isopropyl alcohol as a solvent to prepare a coating liquid, applying the coating liquid to a nonwoven fabric as a substrate, and drying at 90°C or higher for 10 minutes or more.

[0022] Example 6 The film-like composition of Example 6 was prepared by mixing the metal-organic framework MIL-101(Cr) as a moisture absorbent with only maleic anhydride-modified polyolefin as an adhesive curing agent in a predetermined mixing ratio (see Table 1 below), dispersing the precursor in isopropyl alcohol as a solvent to prepare a coating liquid, applying the coating liquid to a nonwoven fabric as a substrate, and drying at 90°C or higher for 10 minutes or more.

[0023] (Examples 7 to 11) The film compositions of Examples 7 to 11 were prepared by mixing the metal-organic framework MIL-101(Cr) as a moisture absorbent with the maleic anhydride-modified polyolefin and the acrylic polymer material as adhesive curing agents in the same predetermined mixing ratios (see Table 2 below) as in Example 4, dispersing the precursor in isopropyl alcohol as a solvent to prepare a coating liquid, applying the coating liquid to different substrates (see Table 2 below) and drying at 90°C or higher for 10 minutes or more.

[0024] Next, the methods for evaluating the appearance, adhesion, and moisture absorption performance carried out in this evaluation will be described.

[0025] (Appearance evaluation) Appearance evaluation was performed on the film-like composition samples of Comparative Example 1 and Examples 1 to 11. In this appearance evaluation, the surface of the film-like composition (see Figs. 2 to 13) was visually observed to determine the presence or absence of cracks and peeling. The results are shown in Tables 1 and 2 below. In the "Cracks" columns of Tables 1 and 2 below, those with cracks are marked with "X" and those without cracks are marked with "O." In the "Peeling" columns of Tables 1 and 2 below, those with peeling are marked with "X," those with slight peeling are marked with "△," and those without peeling are marked with "O."

[0026] (Adhesion evaluation) The samples of the film-like composition of Comparative Example 1 and Examples 1 to 11 were subjected to an adhesion evaluation. In this adhesion evaluation, cellophane tape was attached to the surface of the film-like composition, and the surface of the film-like composition after the attached cellophane tape was peeled off was visually observed, and the presence or absence of peeling of the film-like composition due to the peeling off of the cellophane tape was judged. The results are shown in Tables 1 and 2 below. In the "Adhesion" column of Tables 1 and 2 below, a film-like composition in which the entire film-like composition peeled off when the cellophane tape was peeled off is marked with "X", a film-like composition in which only a part of the film-like composition peeled off when the cellophane tape was peeled off is marked with "△", and a film-like composition in which almost no or only a small amount of the film-like composition peeled off when the cellophane tape was peeled off is marked with "○".

[0027] (Moisture absorption evaluation) A moisture absorption evaluation was carried out on the film-like composition samples of Comparative Example 1 and Examples 1 to 6, which were formed by applying the composition to a nonwoven fabric measuring 10 cm x 10 cm square. In this moisture absorption evaluation, the film-like composition samples formed by applying the composition to a substrate were kept in a thermo-hygrostat at a temperature of 30°C and a relative humidity of 60% for a predetermined time, and the ratio of the weight increase to the initial weight of the film-like composition for each sample after the predetermined time had elapsed was measured as moisture absorption performance (g / g). The results are shown in the graph of FIG. 14, and the moisture absorption performance after 3 minutes and 30 minutes are shown in Table 1 below.

[0028] [Table 1]

[0029] [Table 2]

[0030] (Evaluation result 1) With reference to Table 1 and the graph of FIG. 14, the film-like compositions of Comparative Example 1 and Examples 1 to 6 using nonwoven fabric as a substrate are evaluated. It can be seen that the film compositions of Examples 1, 2, 3, and 4 have high moisture absorption performance from the start. This is understood to be because adjusting the compounding ratio of the maleic anhydride modified polyolefin and the acrylic polymer material as the adhesive curing agent makes it easier for the metal-organic framework MIL-101(Cr) as the moisture absorbent to be applied onto the nonwoven fabric substrate.

[0031] In Examples 1, 2, 4, and 5, the amount of maleic anhydride modified polyolefin and acrylic polymer material as adhesive hardeners was gradually increased relative to the metal-organic framework MIL-101(Cr) as a moisture absorbent, and the moisture absorption of the film-like composition was evaluated, but the moisture absorption performance at a retention time of 30 minutes in particular tends to decrease from Example 4 onwards. This is presumably due to a decrease in the blending ratio of the metal-organic framework MIL-101(Cr) as a moisture absorbent per unit weight due to an increase in the maleic anhydride modified polyolefin and acrylic polymer material, and the possibility that the blockage of the water adsorption sites in the metal-organic framework MIL-101(Cr) as a moisture absorbent may have increased, which ultimately led to a decrease in performance.

[0032] In Example 6, when the total compounding amount of the maleic anhydride modified polyolefin and the acrylic polymer material as the adhesive hardener for the metal-organic framework MIL-101(Cr) as the moisture absorbent was set to the intermediate value between Examples 2 and 4, the moisture absorption performance was not good. Considering this, it can be considered that the use of only the acrylic polymer material alone does not result in good moisture absorption performance. The film-like compositions of Examples 1 to 6, which are made by adding maleic anhydride-modified polyolefin and an acrylic polymer material as an adhesive curing agent to the metal-organic framework MIL-101(Cr) as an adsorbent, have inferior adsorption performance compared to the film-like composition of Comparative Example 1, which is made by adding only an acrylic polymer material to the metal-organic framework MIL-101(Cr), but considering the results of the appearance evaluation and adhesion evaluation described above, it can be said that Comparative Example 1 is not practical. Also, compared to conventional film-like compositions such as those made by adding an acrylic polymer material and a urethane polymer material as a thickener to the metal-organic framework MIL-101(Cr) or those using a polymer adsorbent (such as sodium polyacrylate), the moisture absorption performance after 3 minutes and the moisture absorption performance after 30 minutes are both excellent.

[0033] In addition, regarding the appearance evaluation and adhesion evaluation, the film-like composition of Comparative Example 1, which does not contain maleic anhydride-modified polyolefin, was rated as "x" in all of the evaluations of cracking, peeling, and adhesion, whereas the film-like compositions of Examples 1 to 6, which contain maleic anhydride-modified polyolefin, achieved high evaluations. In particular, the film-like compositions of Examples 2 to 6, in which the blending ratio of maleic anhydride-modified polyolefin to metal-organic framework MIL-101(Cr) is 5 / 100 or more, were rated as "○" in all of the evaluations of cracking, peeling, and adhesion. This can be said to be due to the inclusion of maleic anhydride-modified polyolefin, which suppresses cracking, peeling, and the like, and realizes good film strength and good coatability.

[0034] (Evaluation result 2) With reference to Table 2, the film-like composition of Example 4 using a nonwoven fabric as a substrate and the film-like compositions of Examples 7 to 11 containing maleic anhydride modified polyolefin and acrylic polymer material in the same ratio as in Example 4, but using paper (cardboard), copper, stainless steel, aluminum, or a PET film as a substrate other than nonwoven fabric, are evaluated. The film-like composition of Example 11, which used a PET film as a substrate, was observed peeling off from the edges as it dried, whereas the film-like compositions of Examples 4, 7, 8, 9, and 10, which used nonwoven fabric, paper, copper, stainless steel, and aluminum as substrates, did not crack or peel off and achieved good film strength. [Explanation of symbols]

[0035] A Moisture absorbent B Adhesive hardening material C Solvent D Coating fluid E Membrane composition X Base material

Claims

1. A film-like composition comprising a moisture absorbent and applied onto a substrate, The metal organic framework MIL-101(Cr) having chromium as a central metal is contained as the moisture absorbent, A film-like composition containing a maleic anhydride-modified polyolefin as an adhesive curing agent.

2. 2. The film-like composition according to claim 1, wherein the adhesive hardener comprises an acrylic polymer material.

3. 3. The film-like composition according to claim 1, wherein the substrate is any one selected from the group consisting of nonwoven fabric, paper, aluminum, copper, and stainless steel.

4. A method for producing the film-like composition according to any one of claims 1 to 3, The moisture absorbent, which is a metal organic framework MIL-101(Cr) having chromium as a central metal, and the maleic anhydride modified polyolefin as the adhesive curing agent are dispersed in a solvent containing one or more selected from water, acetone, ethanol, and isopropyl alcohol to prepare a coating liquid; A method for producing a film-like composition, comprising applying the coating liquid onto a substrate and drying the applied coating liquid.

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