JP4271207B2 - High-frequency exothermic molded body and its use - Google Patents

Description

  The present invention relates to a high-frequency exothermic molded body and its use. More specifically, a high-frequency exothermic molded body having an exothermic layer formed from an ion conductive polymer having a surface resistivity of a specific value or less, or an ion conductive polymer composition having a surface resistivity of a specific value or less, and the same It relates to the use.

Synthetic resins that generate heat in a high-frequency electric field include polar plastics such as polyvinyl chloride, polyvinylidene chloride, polyurethane, nylon, nitrile rubber, and phenol resin, but most other synthetic resins generate little heat in a high-frequency electric field. . As a measure of whether a polymer generates heat in a high-frequency electric field, there is a dielectric loss tangent (hereinafter sometimes referred to as tan δ). A polymer having a large value is likely to generate heat in a high-frequency electric field. Conversely, a polymer having a small value is less likely to generate heat in a high-frequency electric field. For example, when measured at 1 MHz, the tan δ value of soft polyvinyl chloride is 4 × 10 ^{−2 to} 1.4 × 10 ⁻¹ . On the other hand, the tan δ value of polyethylene is 5 × 10 ⁻⁴ or less. As a method for imparting heat generation in a high frequency electric field to such a synthetic resin having a low tan δ value, quaternary ammonium salt, 2-oxazolidinone compound, diethylene glycol, ethanolamine, barium titanate, zinc oxide, bentonite clay, carbon A method of blending black or the like has been studied (Hito Ninomiya, polymer processing, vol. 38, No. 7). However, compositions obtained by these methods have difficulty in controlling high-frequency irradiation conditions, and have problems such as deterioration of synthetic resin due to excessive heat generation and generation of sparks. In addition, when using low molecular weight materials such as diethylene glycol, the effect of bleed is poor because of bleed out, and when inorganic or carbon black is used, transparency is lost or coloring is difficult. There was a point.

  Moreover, when warming articles | goods, such as foodstuff, using the high frequency has been generally performed conventionally. However, some articles do not exhibit exothermic properties in a high-frequency electric field, and there has been a demand for means for efficiently heating these articles in a high-frequency electric field.

JP 08-267671 A

  This invention is made | formed in view of such a condition, and makes it a subject to provide the molded object with favorable high frequency exothermic property, and its use.

As a result of intensive research on synthetic resins that generate heat when irradiated with high frequency, the present inventors have found that the surface resistivity of synthetic resins and high-frequency exothermicity are closely related, and the surface resistivity is below a certain value. It has been found that the synthetic resin having good high-frequency exothermic property. As a result of further studies by the present inventors, a molded body having a heat generation layer composed of an ion conductive polymer having a specific surface resistivity or a composition containing an ion conductive polymer composition as an essential component is obtained. It has been found that it exhibits high-frequency exothermicity, and has reached the present invention. That is, according to the present invention, the surface resistivity of ^{1 × 10 11 (Ω / □} ) or less of the ionic conductive polymer, or a surface resistivity of ^{1 × 10 11 (Ω / □} ) or less of the ion conductive polymer composition (A) 5% by weight or more and a heat generating layer comprising a synthetic resin other than (A) or a synthetic resin composition (B) containing 95% by weight or less is used as a core layer, and the outer layers of the core layer are formed on both outer layers. There is provided a high-frequency exothermic molded body obtained by forming a synthetic resin layer selected from polyester, polypropylene, and polystyrene. Also provided is the above-described high-frequency exothermic molded article, wherein the dielectric loss tangent (tan δ) measured at 1 MHz of the synthetic resin or the synthetic resin composition (B) is 1.0 × 10 ⁻² or less. The Preferably, any one of the above-described high-frequency exothermic molded bodies is characterized in that a polyhydric alcohol is contained in (A). Furthermore, the use which uses the high frequency exothermic molded object described in any of the above as a heating medium is provided.

The present invention, a surface resistivity of ^{1 × 10 11 (Ω / □} ) or less of the ionic conductive polymer, or a surface resistivity of ^{1 × 10 11 (Ω / □} ) or less of the ion conductive polymer composition (A) 5% by weight or more and a heat generating layer comprising a synthetic resin other than (A) or a synthetic resin composition (B) containing 95% by weight or less, and polyester, polypropylene, polystyrene from both outer layers of the heat generating layer A high-frequency exothermic molded body formed by forming a selected synthetic resin layer is provided.
According to the present invention, a molded article having good high-frequency exothermic properties is provided. The molded body obtained by the present invention has the feature that it can heat an article in contact with the molded body by utilizing the feature that heat is generated in a high-frequency electric field. Are widely used.

Hereinafter, the present invention will be described in more detail. The high-frequency exothermic molded article of the present invention has at least one exothermic layer that generates heat by high frequency, and the exothermic layer has an ion conductive polymer having a surface resistivity of 1 × 10 ¹¹ (Ω / □) or less, Or it consists of an ion conductive polymer composition (A) whose surface resistivity is adjusted to 1 × 10 ¹¹ (Ω / □) or less and a synthetic resin (B) other than these blended as necessary ( In the following, for simplicity, the ion conductive polymer and the ion conductive polymer composition are collectively referred to as an ion conductive material). Further, the surface resistivity as used in the present invention means that after forming an ion conductive material, it was kept under conditions of 23 ° C. and 50% RH for 24 hours, a voltage of 10 V was applied, and a resistance value after 10 seconds was measured. Say things. When an ion conductive material having a surface resistivity exceeding 1 × 10 ¹¹ (Ω / □) is used, it is not preferable because a good high-frequency exothermic property cannot be imparted to the finally obtained molded body.

The ion conductive material used in the present invention will be described below. Ionic conductive material used in the present invention, the surface resistivity of ^{1 × 10 11 (Ω / □} ) or less of the ionic conductive polymer or various additives are blended, the surface resistivity of 1 × 10 11 ^(Ω / □) It is selected from the ion conductive polymer composition prepared below. That is, when only the ion conductive polymer and the surface resistivity is 1 × 10 ¹¹ (Ω / □) or less, it is not always necessary to take the form of the composition. In addition, these ion conductive polymers differ in the high-frequency exothermic property of the finally obtained high-frequency exothermic resin composition if their molecular structures are different, but if they have the same molecular structure, the surface resistivity Is preferable because it can impart good high-frequency exothermic properties to the high-frequency exothermic resin composition.

As the polymer used for the ion conductive material having a surface resistivity of 1 × 10 ¹¹ (Ω / □) or less, a polymer containing an ionic group such as a quaternary ammonium salt, a sulfonate, or a carboxylate in the molecule, so-called , Ionomers. Polymers having a polyalkylene oxide chain in the molecule such as polyethylene oxide, a copolymer of ethylene oxide and propylene oxide, a copolymer of ethylene oxide and epichlorohydrin, polyether ester, polyether ester amide, etc. Can be mentioned. It is desirable that all of these polymers have a molecular weight of 3000 or more. Further, when the surface resistivity of the polymer itself is 1 × 10 ¹¹ (Ω / □) or less, it can be used alone as the ion conductive material of the present invention. In addition, the polymer described above is an example to the last, and is not limited to these.

Next, in order to obtain an ion conductive material having a surface resistivity of 1 × 10 ¹¹ (Ω / □) or less, various additives that are blended into the polymer as necessary will be described. Among the above polymers, examples of the additive added to the polymer having an ionic group in the molecule, that is, an ionomer, include polyhydric alcohols such as glycerol, diglycerol, and trimethylolpropane. These polyhydric alcohols have the effect of further reducing the surface resistivity of the ionomer. For example, a polyhydric alcohol having a surface resistivity of 1 × 10 ¹¹ is added to a polymer having a surface resistivity higher than 1 × 10 ¹¹ (Ω / □), such as an ionomer having a sodium salt of carboxylic acid in the molecule. When it is blended so as to be (Ω / □) or less, it is suitable as an ion conductive material used in the present invention. The specific blending amount of the polyhydric alcohol is 0.1 to 30 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the ionomer.

On the other hand, as an additive compounded in a polymer having a polyalkylene oxide chain in the molecule, the thiocyanate, phosphate, sulfate, halide, halogen of alkali metal or alkaline earth metal is used. An ionic electrolyte such as an oxyacid salt may be mentioned. More specifically, potassium thiocyanate, sodium thiocyanate, lithium thiocyanate, potassium perchlorate, sodium perchlorate, lithium perchlorate and the like can be exemplified. The blending amount of these ion electrolytes is not particularly limited, but is 0.1 to 30 parts by weight, more preferably 0.2 to 20 parts by weight with respect to 100 parts by weight of the polymer having a polyalkylene oxide chain. In addition, even when the surface resistivity of the polymer itself having a polyalkylene oxide chain is 1 × 10 ¹¹ (Ω / □) or less, the surface resistivity of the polymer is further reduced by using these ion electrolytes in combination. Therefore, the ion conductive material used in the present invention is more suitable. In addition, polyhydric alcohols such as glycerol, diglycerol, and trimethylolpropane have an effect of further reducing the surface resistivity even in an ion conductive material made of a polymer having a polyalkylene oxide chain. Therefore, it is preferable to blend a polyhydric alcohol even in an ion conductive material made of a polymer having a polyalkylene oxide chain having a surface resistivity of 1 × 10 ¹¹ (Ω / □) or less. The specific blending amount of the polyhydric alcohol is 0.1 to 30 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the ionomer.

  The ion conductive material having a lower surface resistivity as described above needs to reduce the blending amount of the ion conductive material in the high-frequency exothermic molded body when a large heat generation amount is required for the high-frequency exothermic molded body. This is particularly effective in certain applications.

  As described above, the ion conductive material used for the heat generating layer of the high-frequency exothermic molded body of the present invention is configured. These ion conductive materials can be used alone or in combination of two or more.

  On the other hand, as the synthetic resin or synthetic resin composition (B) other than the ion conductive material used in the present invention, high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), etc. Α-olefin homopolymers such as polyethylene, polypropylene, polybutene-1 and poly-4-methylpentene-1, ethylene-ethyl acrylate copolymer (EEA), ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid Polyolefin resins such as copolymers of ethylene and other monomers such as copolymers (EAA), ethylene-propylene copolymers, ethylene-butene-1 copolymers, ethylene-propylene-diene copolymers; polystyrene Resin; polycarbonate resin; polyester resin; Amide resins; polyvinyl chloride resins. These can be used in the form of a combined composition if the compatibility is good.

Among the resin groups described above, even in the case of α-olefin homopolymers such as polyethylene, polypropylene, polybutene-1, and poly-4-methylpentene-1, and ethylene-polar monomer copolymers, the content of polar monomers is low. When the present invention is applied to a synthetic resin such as a polymer that has a tan δ value measured at 1 MHz of 1.0 × 10 ⁻² or less and does not inherently exhibit high-frequency exothermic properties, the effects of the present invention can be manifested more remarkably. In addition, tan δ values measured at 1 MHz, such as polyvinyl chloride resins and polyamide resins, exceed 1.0 × 10 ⁻² , and even synthetic resins that inherently have high-frequency exothermic properties can be combined with other synthetic resins, In the case where the tan δ value is 1.0 × 10 ⁻² or less as a whole, the present invention shows a remarkable effect. In the present invention, a thermosetting resin can be used as the synthetic resin as long as it can be combined with an ion conductive material.

  As described above, the heat generating layer of the high-frequency exothermic molded body of the present invention is composed of an ion conductive material and a synthetic resin other than the ion conductive material used as necessary. At this time, the ion conductive material is blended so as to be 5% by weight or more, and the synthetic resin other than the ion conductive material is blended to be 95% by weight or less. If the ratio of the ion conductive material in the heat generating layer is 5% by weight or more, good high-frequency heat generation property is imparted to the heat generating layer. If the proportion of the ion conductive material in the heat generating layer is less than 5% by weight, the effect of imparting high-frequency heat generation to the heat generating layer is not sufficient, which is not preferable.

  In the present invention, for the purpose of improving the compatibility between the ion conductive material and a synthetic resin other than the ion conductive material, a modified polyolefin obtained by grafting an unsaturated carboxylic acid or a derivative thereof into the composition, etc. A compatibilizer suitable for the synthetic resin can be appropriately used. Furthermore, antioxidants, light stabilizers, ultraviolet absorbers, flame retardants, lubricants, antiblocking agents, processing aids, pigments, and the like can be added as necessary.

  The high-frequency exothermic molded article of the present invention is produced by including at least one exothermic layer described above in the molded article. The synthetic resin constituting the layers other than the heat generating layer is not particularly limited, and any synthetic resin can be used. Further, a form in which the heat generating layer is a core layer and other synthetic resin layers are formed on both outer layers of the core layer is preferable, and furthermore, a high melting point such as polyester or polypropylene is used as the synthetic resin forming the both outer layers. Of these, a synthetic resin having heat resistance is most preferable. In addition, the high frequency exothermic molded object of this invention may be comprised only from a heat generating layer. Furthermore, the heat generating layer may be partially provided at a necessary portion of the molded body instead of being provided over the entire surface of the molded body.

  The molding method of the high-frequency exothermic molded body of the present invention may be a known method according to the shape of the target molded body, and by using these methods, the shape of a film, a sheet, a tube, a pipe, a block, a container, etc. To be molded. Furthermore, it is more desirable that one or more of the constituent layers constituting the high-frequency exothermic molded body of the present invention have a three-dimensional cross-linked structure. By taking such a structure, the heat resistance of the molded body is further improved. Specific means for forming such a structure is appropriately selected according to the type of synthetic resin used, such as a method of irradiating various electromagnetic radiation such as an electron beam or a method using an organic peroxide. .

  The molded body thus obtained can be used for various applications utilizing high-frequency heat generation properties, and is particularly useful as a heating medium for substances that do not naturally generate heat in a high-frequency electric field. For example, when applied to foods with poor high-frequency exothermicity, the shape of the high-frequency exothermic molded product of the present invention is made into a tray, film, or sheet, and the food is placed on this and heated in a microwave oven. Good. Moreover, when applying to liquid substances, such as oil, the shape of the high frequency exothermic molded object of this invention should just be a cup shape or a bottle shape. In addition, if a part of the high-frequency exothermic molded body of the present invention formed into a pipe shape is positioned in a high-frequency electric field and a liquid substance such as oil is allowed to flow inside the pipe, these can be continuously heated. Furthermore, the material to be heated can be applied not only to solid and liquid forms but also to gaseous forms.

Hereinafter, the present invention will be described in more detail based on examples. In addition, these Examples are illustrations and are not limited. In the following examples, those shown in Table 1 were used as ion conductive materials (in the following, ion conductive materials are abbreviated as shown in Table 1). Moreover, what was shown below was used as synthetic resins other than an ion conductive material.
Polypropylene (abbreviated as PP): “Noblen WF905E” manufactured by Sumitomo Chemical Co., Ltd. (density: 0.89 g / cm ³ , MI: 3 g / 10 min, melting point: 138 ° C., tan δ value (1 MHz): 0.0005)
Polystyrene (abbreviated as PS): “Topolex 555-57U” manufactured by Mitsui Toatsu Chemical Co., Ltd. (density: 1.05 g / cm ³ , MI: 0.3 g / 10 min, Vicat softening point: 103 ° C., tan δ Value (1 MHz): 0.0002)
The above-described PP and PS were also used as the synthetic resin laminated on the heat generating layer. Furthermore, in Example 12, a polyester sheet (trade name Mylar, thickness: 100 μm) was used as a synthetic resin laminated on the heat generating layer. In Examples 9 and 10, the following were used as compatibilizers.
Acid anhydride-modified low molecular weight polyethylene: “Yumex 2000” (abbreviated as P4) manufactured by Sanyo Chemical Industries, Ltd.

  On the other hand, the surface resistivity measurements shown in Tables 1 and 2 were performed according to the following procedure. The sample was adjusted to a thickness of 100 μm and kept under conditions of 23 ° C. and 50% RH for 24 hours, and then applied using “HIRESTA IP” manufactured by Mitsubishi Chemical Corporation at a voltage of 10 V with an HRS probe. The value was measured.

[Examples 1 to 11 and Comparative Examples 1 to 4]
Each component was charged into the pressure kneader at the ratio shown in Table 3, and after melt-kneading, pelletized. And the sheet | seat for about 1 mm thick heat_generation | fever layers was obtained using the extrusion molding machine (Toyo Seiki Seisakusyo Co., Ltd. product, lab plast mill) provided with T dice | dies. Moreover, the predetermined | prescribed synthetic resin shown in Table 3 was shape | molded into the sheet | seat for outer layers about 1 mm thick using the same extruder. Subsequently, a heat generation press sheet was sandwiched between the two outer layer sheets to obtain a sample for evaluating heat generation. The obtained exothermic evaluation sample was irradiated with a high frequency for 3 minutes in a commercially available microwave oven (500 W, 1240 MHz), and the surface temperature of the exothermic evaluation sample was immediately measured using a surface thermometer. The results are shown in Table 3.

From Table 3, as disclosed in the present invention, a molded body having a heat generating layer formed from a composition containing a predetermined amount of an ion conductive material having a surface resistivity of 1 × 10 ¹¹ (Ω / □) or less is a high-frequency electric field. It can be seen that it exhibits exothermic properties. Further, by adding a polyhydric alcohol to the ion conductive material by comparing Example 1 and Example 2, comparing Example 6 and Example 8, and comparing Example 9 and Example 10, high frequency It turns out that exothermic property improves. In addition, as shown in Comparative Example 1, a molded body using a sodium salt ionomer having a surface resistivity exceeding a predetermined value as a heat generating layer hardly exhibits high-frequency exothermic properties. It can be seen that the molded article of Example 5 using an ion conductive material having a surface resistivity of not more than a predetermined value by using as a heat generating layer exhibits exothermic properties. Further, from Comparative Example 2, even a molded body using an ion conductive material having a surface resistivity of a predetermined value or less in the heat generation layer shows almost no high-frequency heat generation when the blending amount of the ion conductive material is less than 5% by weight. I understand that.

[Example 12]
A sheet for the heat generating layer similar to that in Example 7 was obtained. Subsequently, the sheet for the heat generation layer was sandwiched between two polyester sheets (trade name Mylar, thickness: 100 μm), and hot-pressed to obtain a sample for exothermic evaluation. When the obtained exothermic evaluation sample was put in a commercially available microwave oven (500 W, 1240 MHz) and irradiated with high frequency for 3 minutes, the surface temperature of the exothermic evaluation sample was immediately measured using a surface thermometer. It was confirmed that the exothermic evaluation sample had a good high-frequency exothermic property.

[Comparative Example 5]
A polyester sheet (trade name Mylar, thickness: 100 μm) was placed in a commercially available microwave oven (500 W, 1240 MHz), irradiated with a high frequency for 3 minutes, and immediately the surface temperature of the polyester sheet was measured using a surface thermometer. However, it was 38 ° C. and did not show high-frequency exothermicity.

  As described above, according to the present invention, a molded article having good high-frequency heat generation properties is provided. The molded body obtained by the present invention has the feature that it can heat an article in contact with the molded body by utilizing the feature that heat is generated in a high-frequency electric field. Are widely used.

Claims (4)

Surface resistivity of ^{1 × 10 11 (Ω / □} ) or less of the ionic conductive polymer, or a surface resistivity of ^{1 × 10 11 (Ω / □} ) or less of the ion conductive polymer composition (A) 5 wt% or more And a heat generating layer made of a composition containing synthetic resin other than (A) or a synthetic resin composition (B) of 95% by weight or less is used as a core layer, and both outer layers of the core layer are selected from polyester, polypropylene, and polystyrene. A high-frequency exothermic molded body formed by forming a synthetic resin layer. 2. The high-frequency exothermic molded article according to claim 1, wherein a dielectric loss tangent (tan δ) of the synthetic resin or the synthetic resin composition (B) measured at 1 MHz is 1.0 × 10 ⁻² or less.   3. The high-frequency exothermic molded article according to claim 1, wherein the (A) contains a polyhydric alcohol.   A heating medium comprising the high-frequency exothermic molded article according to any one of claims 1 to 3.