JP4475048B2 - Variable shape drying member - Google Patents

Description

The present invention provides a drying member formed from a resin composition in which a desiccant (B) is blended with a thermoplastic resin (A), the shape of which is a sheet shape, and a lattice-shaped cutout is provided on the surface. It is related with the shape-variable drying member characterized by these. More specifically, since the lattice-shaped notches can perform various functions by performing the function of “sheet tearing” or “sheet folding”, a container in which a drying member is loaded. The present invention relates to a shape-variable drying member that is excellent in moisture absorption speed because it can be designed in shape according to the space and at the same time the surface area can be increased.

In the field of packaging business for packaging various contents, the keywords of “package” or “packaging” can include the following contents.
(1) “Display effects” such as giving consumers purchase awareness and presenting dangers
(2) “Content resistance” to prevent the package from being attacked by the filled contents themselves
(3) “Protection of contents” against external stimuli
These keywords are further subdivided and expanded to fine required quality. Among them, the protection of contents from oxygen and moisture is particularly attracting attention in terms of “protection of contents”. In recent years, in particular, in the fields of food, industrial products, medical / pharmaceuticals, etc., the protection of contents against oxygen and moisture has become important. As the background, there are oxygen content decomposition and alteration due to oxidation, and moisture content alteration due to moisture absorption and hydrolysis.

  Various methods have been studied in order to prevent the contents from being altered by oxygen or moisture. One of them is to design a package using a material having an oxygen barrier or moisture barrier property. In terms of oxygen barrier properties, a packaging material using a substrate having excellent oxygen barrier properties such as an aluminum foil, an inorganic compound vapor deposition film, and an ethylene-vinyl alcohol copolymer has been proposed. In terms of moisture barrier, moisture-proof polyolefin resins, and packaging materials that use moisture-proof films by providing polyvinylidene chloride coating layers on these polyolefin resins, polyester resins, and polyamide resins Is the most common.

  Packagings using these oxygen and moisture barrier base materials are widely used in various applications because of their high oxygen and moisture barrier properties. However, these barrier mechanisms only prevent the permeation of oxygen and moisture entering from the outside of the packaging material, and some contents may be deteriorated by slight oxygen or moisture in the headspace. There is also. In that sense, there is a need to remove not only oxygen and moisture barrier properties from the outside of the packaging container but also oxygen and moisture in the container main body head space.

In terms of the design of a package having a function of absorbing oxygen and moisture in the container head space, the following types can be mentioned.
(1) A type in which various containers are filled with a small bag of oxygen absorbent or desiccant in the cap or container body. (2) By kneading the oxygen absorbent or desiccant into the resin, the container body itself absorbs oxygen and moisture. These technologies are already known technologies.

In the case of (1), a sachet-shaped oxygen scavenger or desiccant is blended with the contents, or a sachet-shaped desiccant provided with an adhesive is bonded to the inside of the cap or lid, etc. Attempts have been made to remove oxygen or moisture in the container. However, the sachet-shaped desiccant has problems of accidental ingestion and accidental eating, and has a problem that the mounting process is complicated when it is attached to the inside of a cap or lid using an adhesive. Moreover, as a desiccant loaded inside the cap, a case where an inorganic compound having a drying function is made together with various inorganic binders to form a tablet-like molded body can be seen. However, these molded bodies are often destroyed by a slight stress or vibration, and in the worst case, there is a possibility that a problem of foreign matter mixing into the contents may occur. In order to avoid the problem, a type in which this tablet-like molded product is wrapped with thin paper has been seen, but in this case, the thin paper that wraps the tablet-like desiccant removes moisture in the container. It has become regarded as a problem to have an adverse effect on doing so. From this point of view, container design using the type (2) has become mainstream (see, for example, Patent Document 1).

The said prior art document is shown.
US Pat. No. 6,214,255 B1.

  The “drying container in which a desiccant is blended in a polymer” described in Patent Document 1 is a container type in which a drying function is imparted to the container itself, but the container is molded by a two-color injection molding method. In order to integrate the two parts of the “resin composition layer containing desiccant” and “moisture-proof layer for imparting moisture-proofing”, which constitute the container, using a single molding machine, There are concerns about the problem that the manufacturing method is complicated and the versatility is inferior because a dedicated device / mold is required, and the strength properties of the container due to the occurrence of cracks in the container are concerned. Furthermore, there are problems such as discoloration of the container and bleeding of low molecular weight components.

  In particular, the neck of the drying container described in Patent Document 1 is that the molding method is limited. In recent years, there are many medical / pharmaceutical products, electronic devices, and the like as contents that require a drying function. A case in which a drying function is given to a container filled with these contents will be described with reference to FIG.

  FIG. 1 shows an example in which a space (11) for filling a case (injection molded product) with a content and a space (12) for filling a desiccant are provided. These shapes are similar to those of portable cases used for contents that require moisture absorption, such as taste foods and supplement foods. However, the case of such a shape can be formed by the molding method of Citation 1. Therefore, it is difficult to meet market demands. As shown in FIG. 1A, conventionally, the space (12) in which the desiccant is filled is directly filled with a desiccant. Therefore, as shown in FIG. 1 (b), by mixing the desiccant with the thermoplastic resin, the bulk of the desiccant is dried so as to match the shape of the space (12) filled with the desiccant (high degree of freedom in shape). Attempts have been made to load components. However, this shape was able to avoid problems such as contamination with foreign matter, but because of the lump shape, the moisture absorption efficiency of the desiccant blended in the resin composition was deteriorated, and the moisture absorption rate was inferior to that of the desiccant alone. I had a problem.

  An object of the present invention is to consider the above situation, and suggests a drying agent having a high degree of freedom in shape and a high moisture absorption rate regardless of the container shape.

The present invention has been conceived in order to overcome the above-mentioned problems, and the invention according to claim 1 includes a thermoplastic resin (A) having periodic tables III, IV, V of cyclopentadienyl derivatives. , VI, IX, X A density obtained from a single site catalyst obtained by adding methylaluminoxane to a complex composed of a transition metal atom is 0.880 g / cm ³ or more, 0.930 g / cm ³ or less, flexural modulus Is an ethylene-α-olefin copolymer having a viscosity of 250 MPa or less as an essential component, and the desiccant (B) is at least one of zeolite, calcium oxide, calcium chloride, shochu liquor, magnesium sulfate, alumina, activated carbon, clay mineral, and silica gel. A resin composition selected from more than one species and blended with the thermoplastic resin (A) and the desiccant (B) is formed into a sheet shape, which is staggered on the front and back of the sheet. And the sheet | seat by which the lattice-shaped notch part which can be cut is provided, and the ethylene-alpha olefin copolymer obtained using the said single site catalyst is mix | blended as an essential component with the said resin composition. Is a shape-variable drying member characterized in that generation of cracks and cracks from the notch when the notch is bent is suppressed .

  From the above results, the shape-variable drying member of the present invention can easily change the shape of the drying member regardless of the shape of the container, and the moisture absorption speed as the drying member is also fast. It can be deployed in containers of any shape that require a drying function. In addition, in this content, it was explained with a desiccant capable of providing a completely dry state, but in applications where a humidity control function is required, it is possible to provide a humidity control function by selecting a desiccant. It is.

  Hereinafter, the present invention will be described in detail with reference to FIGS. The shape-variable drying agent of the present invention is a sheet-shaped component comprising a resin composition in which a drying agent (B) is blended with a thermoplastic resin (A). It has a notch (13) that performs the function of “cutting” or “sheet folding”.

  The thermoplastic resin (A) has, as an essential component, a complex composed of group III, IV, V, VI, IX, X transition metal atoms of the periodic table of cyclopentadienyl derivatives and the above metal complexes as required. Then, an ethylene-α olefin copolymer obtained by using a single site catalyst made of methylaluminoxane is blended. The blending ratio is preferably 50 wt% or more of the thermoplastic resin (A).

Examples of such a catalyst include a single site catalyst (Kaminsky catalyst) obtained by adding methylaminoxan to bis (cyclopentadienyl) zirconium chloride and derivatives thereof. As the metal, a periodic group IV transition metal such as titanium, zirconium or hafnium is particularly used, but is not particularly limited thereto. The above catalyst has a structure in which a transition metal is introduced into two bulky cyclopentadienyl groups. By using a titanium-based geometrically constrained catalyst, a higher grade of C ₆ , C ₈ , or C ₉ or higher. Alpha olefins can also be introduced.

Further, those having a density of 0.880 or more and 0.930 g / cm ³ or less, particularly those having a density region of 0.850 to 0.925 g / cm ³ enter the region of polyolefin elastomer or plastomer, and are referred to as adhesive properties and strength physical properties. Very preferable in terms. In particular, an ethylene-α olefin copolymer using a single site catalyst is excellent in dispersibility of inorganic compounds. In particular, the above density range is still effective.

  Furthermore, the ethylene-α olefin copolymer obtained by using this single site catalyst is very preferably used in terms of strength properties and flexibility. As will be described later in particular, this drying component imparts “foldability” by utilizing a notch (13) provided on the sheet surface (front and back). Usually, a resin composition containing a high content of an inorganic compound becomes brittle and easily cracks. However, by using an ethylene-α olefin copolymer obtained by using a single site catalyst, particularly one having a flexural modulus of 250 MPa or less, it is possible to improve the brittleness caused by blending an inorganic compound. In addition, using the above-described notch portion (13), it is possible to impart “appropriate sheet tearability” functionally.

  Using ethylene-α olefin copolymer obtained by using such a single-site catalyst as an essential component, other thermoplastic resins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and multi-site catalyst can be used. Various polyolefin resins such as ethylene-α olefin copolymer, polypropylene resin (including homo, block, random), propylene-α olefin copolymer, cyclic olefin copolymer, ethylene- (meth) acrylic acid copolymer or Various types of ethylene-based copolymers such as esterified products, ionic cross-linked products, ethylene-vinyl acetate copolymers, partial or completely saponified products thereof, and the like are not limited.

  The desiccant (B) is selected from at least one of zeolite, calcium oxide, calcium chloride, zinc oxide, barium titanate, sulfate compounds such as magnesium sulfate and calcined meteorite, alumina, activated carbon, clay mineral, and silica gel. The These materials can be selected according to the required moisture absorption function, and if it is desired to keep the inside of the container completely dry, it is difficult to release moisture that has been absorbed, and materials that have moisture absorption performance even at low humidity. Preferably, zeolite, calcium oxide, silica gel and the like are preferably selected. On the other hand, when it is desired to control (humidify) the inside of the container within a certain range of relative humidity, a desiccant capable of adsorbing and desorbing moisture is preferable, and sulfate compounds such as magnesium sulfate and calcined meteorite are preferable. These inorganic compounds may be pretreated (surface treatment) in advance for improving dispersibility.

  Resin compositions containing these thermoplastic resins (A) and desiccants (B) have various functions such as dispersants, antiblocking agents, slip agents, antioxidants, weathering agents, and flame retardants in terms of other functions. May contain an additive.

The resin composition in which the thermoplastic resin (A) and the desiccant (B) are blended is formed into a sheet shape, and the surface (including the front and back surfaces) has a cutout portion that functions as “sheet tearing” or “sheet folding”. (13) (FIG. 3). By providing the notches (13) so as to be alternated on the front and back as shown in FIG. 3, it becomes possible to impart the “sheet folding” aptitude. By using this notch (13), it is possible to form a drying member having substantially the same shape as the blocky drying agent shown in FIG. 5 as shown in FIG. The merit of the shape of FIG. 4 is that the surface area can be improved as compared with the shape of FIG. That is, the surface area of the lump-shaped drying member shown in FIG. 5 is (a) cm ² , and the surface area of the drying member of the present invention when formed in the same shape as the lump-shaped drying member is (b) cm ² . When the surface area ratio (b) / (a) is 1.5 or more, the moisture absorption rate can be improved.

  As a method for producing the resin composition, a material prepared by adjusting the desiccant (B) according to the purpose to 1 to 50 wt% and the thermoplastic resin (A) to 50 to 99 wt% is a ribbon mixer, a tumbler mixer, Henschel. Dry blending using a mixer, etc., using a kneader such as a single screw extruder or twin screw extruder, Banbury, etc., depending on the base thermoplastic resin, but a melting point of 280 ° C. or less, It is preferably obtained by kneading at 260 ° C. or lower, more preferably 240 ° C. or lower. In that case, you may surface-treat various functional phases with dispersing agents, such as an olefin type wax, as needed. The obtained strand is cooled by air cooling or water cooling, and after pelletizing, it is stored in a packaging form such as an aluminum bag. It can be obtained by molding by a technique such as injection molding or sheet molding.

  The drying member thus obtained can be loaded into various containers by tearing or bending using the notch (13) according to the required absorption capacity and container shape. (See FIG. 1C).

Examples of the present invention are shown below, but are not limited thereto.
<Selection of thermoplastic resin (A)>
A-1: Ethylene-hexene-1 copolymer (single site MI = 23, flexural modulus 80 MPa)
A-2: Low density polyethylene (MI = 25, flexural modulus 650 MPa).
<Selection of desiccant (B)>
B-1: Calcium oxide CaO (for absolutely dry)
<Creation of resin composition>
As shown in the following examples, a mixture containing 60 wt% of the thermoplastic resin (A), 40 wt% of the desiccant (B), and a dispersing agent as necessary was mixed with a twin-screw extruder (φ = 30, L / L). Compounding was performed at a discharge of 9 kg, 200 ° C., and 50 rpm according to D = 49) The obtained compound was stored in an aluminum package (replaced with inert gas). This compound was molded by injection molding to form a dry member having a grid shape of 150 mm × 20 mm, a thickness of 1 mm, and notch portions (13) at intervals of 1 mm.
<Experiment 1>
[Hygroscopic function evaluation]

As a thermoplastic resin (A), A-1 was 40 wt%, A-2 was 20 wt% (60 wt% as the thermoplastic resin (A)), and a desiccant (B) was 40 wt%. The sheet-like sample of 150 mm × 20 mm and 1 mm in thickness is first cut using the cutout portion (C) so as to be 10 mm × 10 mm, and then the cutout portion (C) is used so as to have an interval of 25 mm. The sheet was bent to prepare a dry member having a thickness of 25 mm and a thickness of 4 mm. The effective surface area at this time is about 2280 mm ² . At this time, the suitability for tearing, the bending property, and the moisture absorption capacity at 40 ° C.-90% relative humidity were measured.
(Comparative Example 1)

Using the resin composition described in Example 1, a dry member having a size of 25 mm × 10 mm and a thickness of 4 mm was directly molded. The effective surface area at this time is 780 mm ² . The moisture absorption capacity at 40 ° C.-90% relative humidity at that time was measured.
(Comparative Example 2)

  In the resin composition described in Example 1, A-1 was not used, and A-2 was changed to 60 wt%, and the same molding evaluation as in Example 1 was performed.

  The measurement results of Example 1, Comparative Example 1, and Comparative Example 2 are shown in FIG.

FIG. 6 also confirms that the effective moisture surface area of the drying member of the present invention is large, and the initial moisture absorption rate is remarkably improved even though the blending amount of the desiccant is almost the same. It was confirmed that the effect of blending the single-site catalyst ethylene-α olefin copolymer of the thermoplastic resin (A) has a great influence on the tearability and bendability. In the state of Comparative Example 2, the moisture absorption rate is Although it is the same as Example 1, it was hard to tear and in the case of bending, a crack and a crack entered from the notch part (13), and problems, such as mixing of a foreign material, occurred.
<Experiment 2>
[In-container humidity evaluation]

As shown in FIG. 1C, the drying member described in Example 1 was assembled in a container prepared by injection molding, and the change in humidity in the container over time was observed. The volume of the injection molded container at this time is 100 cm ³ . The container humidity was set by a humidity sensor (14) as shown in FIG.
(Comparative Example 3)

  As shown in FIG. 1B, the drying member described in Comparative Example 1 was incorporated into a container, and the change in humidity in the container over time was observed.

  The measurement results of Example 2 and Comparative Example 3 are shown in Table 1.

表１からも確認されるように、本発明の乾燥部材は吸湿速度が速いゆえ、保存初期で容器内の湿度を１０％相対湿度以下にすることが可能である。

As can be seen from Table 1, the drying member of the present invention has a high moisture absorption rate, so that the humidity in the container can be 10% relative humidity or less at the initial stage of storage.

It is an example of a drying member built-in container. It is a schematic diagram of a drying member. It is an example which provides the notch part (13) in a drying member. It is an example of the bending function which provided the notch part (13). It is an example of a blocky drying member. It is a moisture absorption behavior of the drying member under 40 ° C-90% relative humidity. It is an example of sensor introduction of a drying member built-in container.

Explanation of symbols

10 ... Container body 11 ... Space for filling contents 12 ... Space for filling desiccant 13 ... Notch 14 ... Sensor A ... Thermoplastic resin A
B ... Desiccant B

Claims (1)

The thermoplastic resin (A) is formed by addition cyclopentadienyl derivatives Periodic Table III of, IV, V, VI, IX, methyl aluminoxane complex consisting of X transition metal atom, with a single site catalyst An ethylene-α olefin copolymer having a density of 0.880 g / cm ³ or more and 0.930 g / cm ³ or less and a flexural modulus of 250 MPa or less obtained as an essential component ,
The desiccant (B) is selected from at least one of zeolite, calcium oxide, calcium chloride, shochu cake, magnesium sulfate, alumina, activated carbon, clay mineral, silica gel,
A resin composition in which the desiccant (B) is blended with the thermoplastic resin (A) is formed into a sheet shape, and is provided with lattice-shaped cutout portions that are staggered on the front and back of the sheet and that can be torn. From the notch when the sheet is bent at the notch, the ethylene-α olefin copolymer obtained using the single-site catalyst is blended as an essential component in the resin composition. The shape-variable drying member , characterized in that the occurrence of cracks and cracks is suppressed .

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