JPH01311172A - Susceptor for microwave oven - Google Patents

Abstract

PURPOSE:To obtain a repeatedly usable susceptor, consisting of a film or sheet prepared by filling a filler having a specific value or below of dielectric loss in a thermotropic liquid crystal polymer, excellent in heat resistance and useful for microwave ovens. CONSTITUTION:A susceptor, consisting of a film or sheet obtained by blending (A) 100 pts.wt. thermotropic liquid crystal polymer, preferably a (co)polymer containing monomer units expressed by at least the formula, especially wholly aromatic polyester with (B) 5-150 pts.wt. filler, selected from barium titanate, calcium titanate, magnesium titanate, lanthanum titanate, barium zirconate, etc., and having >=0.8 dielectric loss, preferably barium titanate and, as necessary, inorganic or organic filler, stabilizer, antioxidant, ultraviolet ray absorber, etc., capable of optionally providing foods with scorch patterns and useful for microwave ovens.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a susceptor for a microwave oven.

A susceptor is a film or sheet that absorbs microwaves and uses the energy to generate heat by dielectric heating, and in the present invention, it refers to a film or sheet used in a microwave oven to brown foods.

(Prior Art) Various methods of browning foods using microwaves have been tried. For example, a method is widely known in which food is brought into contact with a microwave heating element made of a laminate including a thin film layer of vapor-deposited metal, and the contact area is browned. However, depending on the food to be heated and the heating method, if the contact between the microwave heating element and the food is poor, it takes time to brown the food, and the browning becomes uneven.

In addition, Japanese Utility Model Application Publication No. 63-41895 discloses 8! which is made of a shrinkable polyester film/aluminum vapor deposited layer/paper and which solves these drawbacks. Examples of layers are disclosed. However, it does not have sufficient heat resistance, and since it is mainly used as a disposable item, it is difficult to use it repeatedly.

(Problems to be Solved by the Invention) Therefore, the present inventors conducted intensive studies to develop a susceptor for microwave ovens that is highly heat resistant and can be used repeatedly, and as a result, the present invention was achieved.

(Means for Solving the Problem) That is, the present invention relates to a susceptor for a microwave oven which is made of a film or sheet filled with a filler having a dielectric loss (tan δ of 08 or more) in a thermotropic liquid crystal polymer. It is something.

The heating effect of microwaves is based on the frictional heat between molecules vibrated by the microwave electric field, and the object to be heated itself becomes the heat generation source. The energy W generated in this case is given by the following equation.

W=kE fc tan δ (where: proportionality constant E: electric field strength f: frequency ε: dielectric constant nδ: dielectric loss tangent) Among these constants, C and tan δ are constants based on the unique properties of the heated object, k and E are constants specific to the microwave generator.

Heat is generated due to the dielectric loss represented by this energy W, and the magnitude thereof is proportional to c tan δ. Therefore, in order to reduce the energy loss due to this heat generation, it is desirable to use a material with small ε tan δ for the microwave oven container. In fact, an example of a commonly used container is pottery (ε
tan δ = 01 to 0.2), glass (ε tan δ = 0
．． 5), plastic (ε tan δ = 0.005 to 0
1) etc. The susceptor of the present invention utilizes this dielectric loss. That is, the dielectric loss ε tl
A film or sheet characterized by filling a thermotropic liquid crystal polymer with a filler having an nδ value of 08 or more, which has high absorption of microwaves and therefore generates a large amount of heat, thereby achieving the object of the present invention. can be reached.

The type of filler having a dielectric loss ε tan δ of 08 or more is not particularly limited, but specific examples include barium titanate, calcium titanate, magnesium titanate,
Examples include lanthanum titanate, barium zirconate, calcium zirconate, magnesium zirconate, and lanthanum zirconate. Preferably barium titanate is used. Further, these may be used in the type 1tIJ or two or more types depending on the purpose.

In the case of a filler having a dielectric loss ε tan δ smaller than 08, the effect of the present invention cannot be obtained because it cannot be easily and appropriately browned.

The filling amount of the filler is usually 5 to 150 parts by weight per 100 parts by weight of the thermotropic liquid crystal polymer; if it is out of this range, the surface will become rough, the hue will deteriorate, and the function as a film or sheet will deteriorate. It may be insufficient, or the browning effect which is the objective of the present invention cannot be sufficiently obtained.

The thermotropic liquid crystal polymer referred to in the present invention is a thermoplastic meltable polymer that exhibits optical anisotropy when melted.

Such a polymer exhibiting optical anisotropy when melted has a property in which the polymer molecular chains take a regular parallel arrangement in the melted state. The nature of the optically anisotropic melt phase can be confirmed by conventional polarization testing using crossed polarizers.

Thermotropic liquid crystal polymers are typically made from monomers that are elongated, flat, and have multiple chain extension bonds in either coaxial or parallel relationships that are highly rigid along the long chains of the molecules. .

As the constituent components of the polymer that forms an optically anisotropic melt phase as described above, (A) at least 1811 of an aromatic dicarboxylic acid or alicyclic dicarboxylic acid-based compound (B) at least 1811 of an aromatic hydroxycarboxylic acid-based compound (C) At least one type of aromatic diol, alicyclic diol, or aliphatic diol compound; (D) At least one type of aromatic dithiol, aromatic thiophenol, or aromatic thiol carboxylic acid compound; (E
) At least one of aromatic hydroxyamines and aromatic diamine compounds may be mentioned. These (sometimes they consist of only one thing, but most of them are (A) and (C), (A) and (D), (A)
It is configured by combining (B) and (C), (A) (B) and (E), or [A) (B) (C) and (E).

Examples of the aromatic dicarboxylic acid compound (AI) include terephthalic acid, 4,4'-diphenyldicarboxylic acid, and 9.4.
4'-triphenyldicarboxylic acid, 2,6-naphthalenedicarbone fil, 1,4-naphthalenedicarbone fil
, 2.7-naphthalene dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenoxyethane-4
゜4'-dicarboxylic acid, diphenoxybutane-4,4'
-dicarboxylic acid, diphenylethane-4,4'-dicarboxylic acid, isophthalic acid, diphenylether-3,3'
- aromatic dicarboxylic acids such as dicarboxylic acid, diphenoxyethane-3,3'-dicarboxylic acid, diphenylethane-3,3'-dicarboxylic acid, 1,6-naphthalene dicarboxylic acid or chloroterephthalic acid, dichloroterephthalic acid, bromo Examples include alkyl, alkoxy or halogen substituted products of the above aromatic dicarboxylic acids, such as terephthalic acid, methylterephthalic acid, dimethylterephthalic acid, ethylterephthalic acid, methoxyterephthalic acid, and ethoxyterephthalic acid.

(A2) As the alicyclic dicarboxylic acid, trans-1,
Alicyclic dicarboxylic acids such as 4-cyclohexanedicarboxylic acid, cis-1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, or trans-1,
Examples include alkyl, alkoxy or halogen substituted products of the above alicyclic dicarboxylic acids, such as 4-(2-methyl)cyclohexanedicarboxylic acid and trans-1,4-(2-chloro)cyclohexanedicarboxylic acid.

(B) As the aromatic hydroxycarboxylic acid compound,
4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6
-Hydroxy-2-naphthoic acid, 6-hydroxy-1-
Aromatic hydroxycarboxylic acids such as naphthoic acid or 3-
Methyl-4-hydroxybenzoic acid, 3,5-dimethyl-
4-hydroxybenzoic acid, 2,6-dimethyl-4-hydroxybenzoic acid, 3-methoxy-4-hydroxybenzoic acid, 3,5-dimethoxy-4-hydroxybenzoic acid, 6
-Hydroxy-5-methyl-2-naphthoic acid, 6-hydroxy-5-methoxy-2-naphthoic acid, 2-chloro-
4-hydroxybenzoic acid, 3-chloro-4-hydroxybenzoic acid, 2,3-dichloro-4-hydroxybenzoic acid, 3,5-dichloro-4-hydroxybenzoic acid, 2゜5
-dichloro-4- to dolochilebenzoic acid, 3-bromo-4
- and droxybenzoic acid, 6-hydroxy-5-chloro-
Alkyl aromatic hydroxycarboxylic acids such as 2-naphthoic acid, 6-hydroxy-7-chloro-2-naphthoic acid, 6-droxy-5゜7-dichloro-2-naphthoic acid,
Examples include alkoxy or halogen substituted products.

(C1) Aromatic diols include 4.4'-dihydroxydiphenyl, 3.3'-dihydroxydiphenyl,
4.4'~dihydroxytriphenyl, hydroquinone, resorcinol, 2,6~naphthalenediol, 4.4'
-dihydroxyldiphenyl ether, bis(4-hydroxyphenoxy)ethane, 3,3'-dihydroxyldiphenyl ether, 1,6-naphthalenediol, 2,2
-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)propane,
Aromatic diols such as -hydroxyphenyl)methane or chlorohydroquinone, methylhydroquinone, t-
'Butylhydroquinone, fynylhydroquinone, methoxyhydroquinone, phenoxyhydroquinone, 4
Examples include alkyl, alkoxy or halogen substituted aromatic diols such as -chlororesorcin and 4-methylresorcin.

(C2) As the alicyclic diol, trans-1,4-
Cyclohexanediol, cis-1,4-cyclohexanediol, trans-1,4-cyclohexane dimetatool, cis-1,4-cyclohexane dimetatool,
trans-1,3-cyclohexanediol, cis-1
, 2-cyclohexanediol, trans-1,3-cyclohexane dimetatool or trans-1,4-(2-methyl)cyclohexanediol, trans-1,4-(2-chloro)cyclohexane Diols include alkyl, alkoxy or halogen substituted alicyclic diols.

(C3) Aliphatic diols include linear or branched aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, and neopentyl glycol.

(Dl) As the aromatic dithiol, benzene-1,4
-dithiol, benzene-1,3-dithiol, 2,6
-naphthalene-dithiol, 2,7-naphthalene-dithiol, and the like.

(D2) Aromatic mercaptocarboxylic acids include 4-mercaptobenzoic Mi, 3-mercaptobenzoic acid, 6-mercapto-2-naphthoic acid, 7-mercapto-2-naphthoic acid, and the like.

(D3) Aromatic mercaptophenol includes 4-mercaptophenol, 3-mercaptophenol, 6-mercaptophenol,
Examples include mercaptophenol.

(E) Aromatic hydroxyamine and aromatic diamine compounds include 4-aminophenol, N-methyl-4-
Aminophenol, 1,4-phenylenediamine, N-
Methyl-1,4-phenylenediamine, N,N'-dimethyl-1,4-phenylenediamine, 3-aminophenol, 3-methyl-4-aminophenol, 2-chloro-4-aminophenol, 4-amino- 1-naphthol, 4-amino-4'-hydroxydiphenyl, 4-amino-4'-hydroxydiphenyl ether, 4-amino-4'-hydroxydiphenylmethane, 4-amino-
4'-Hydroxydiphenyl sulfide, 4.4'-diaminophenyl sulfide (thiothia triphosphate) 4.4
'-Diamino phenyl sulfone, 2,5-diaminotoluene, 4.4'-ethylene dianiline, 4.4'-diaminodiphenoxyethane, 4.4'-diaminodiphenylmethane (methylene dianiline), 4.4'- Examples include diaminodiphenyl ether (oxydianiline).

The thermotropic liquid crystal polymer used in the present invention can be produced from the above compound by various ester forming methods such as melt acidolysis and slurry polymerization.

The thermotropic liquid crystal polymer used in the present invention includes a thermoplastic resin in which a part of one polymer chain is composed of a polymer segment that forms an anisotropic melt phase, and the remaining part is a thermoplastic resin that does not form an anisotropic melt phase. Also included are polymers composed of segments. Also included are composites of multiple thermotropic liquid crystal polymers.

Among these thermotropic liquid crystal polymers, preferred are (co)polymers containing at least monomer units represented by the general formula.

Among the thermotropic liquid crystal polymers used in the present invention,
Other additives may be incorporated without departing from the spirit of the invention. These include inorganic fillers, organic fillers, stabilizers, antioxidants, ultraviolet absorbers, pigments, dyes, modifiers, and the like.

Among these, inorganic fillers are particularly important and are often used to improve processability, physical properties, etc. Inorganic fillers include molybdenum disulfide, talc, mica, clay, sericite, calcium carbonate, calcium silicate, silica, alumina, aluminum hydroxide, calcium hydroxide, graphite, potassium titanate, glass m fiber, carbon fiber, There are various types of whiskers.

The shape of the susceptor for a microwave oven according to the present invention is not particularly limited as long as it is in the form of a film or sheet, but as a preferable example, the thickness is 0.05+n+++~3I! A flat plate in the I- range is preferable. Here, the difference between film and sheet is that film is usually 0.25 mm or less, and film is 0.25 mm or less.
5m+a or more is considered to be a sheet. Further, these films or sheets may be used by making holes in a portion thereof, or by making them into corrugated sheets. Specifically, these films or sheets can be used as a lid or spread on the bottom.

(Effects of the Invention) By simply using the susceptor for a microwave oven according to the present invention, food can be arbitrarily browned using microwave waves, and the effect is amazing. It was completely unexpected that the workmanship could be improved, and the effect is significant.

As an application example of the present invention, the filler is not applied uniformly over the entire surface,
For example, it is possible to fill specific letters and shapes, and in this case, each specific letter and shape can be browned, which has the effect of making the food stand out even more.

Further, the susceptor for a microwave oven according to the present invention has excellent heat resistance and can be used repeatedly.

(Example) The present invention will be explained below with reference to Examples and Comparative Examples.

Example 1 As a thermotropic liquid crystal polymer, Xydar (trade name of Nippon Petrochemical) SRT-500 is a terpolymer of hydroxybenzoic acid, biphenol, and terephthalic acid.
It was used.

For 100 parts by weight of this thermotropic liquid crystal polymer, paris titanate + 7 μm (BaTiO, c tan δ = 1
) using a material filled with 100 parts by weight.
．． A sheet of 0+nm x 100mn+ x 1100n was made.

The sheet from Otsu was used as a lid for a 500 ml Ultra 21 (trade name of Nippon Tupperware) containing gratin ingredients in advance, and heated in a commercially available 1000 W microwave oven.

As a result, the area covered with the sheet was crispy and nicely browned.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the thermotropic liquid crystal polymer was not filled with barium titanate.

As a result, almost no browning was observed even when the sheet was covered.

Patent applicant: Japan Petrochemical Co., Ltd. Patent attorney: Ryoji Kawase -Sa'1. - Procedural amendment March 6, 1999 Director General of the Patent Office Yoshi 1) Tsuyoshi Moon 1, Indication of the case 1988 Patent Application No. 141591, Name of the invention Susceptor for microwave oven 3, Person making the amendment Case and Relationship between Patent applicant name Nippon Petrochemical Co., Ltd. 4, Detailed explanation of the invention column 6 in the agent's specification, Contents of amendment [11 Change the "trade name of Nippon Petrochemical Co., Ltd." on page 14, line 16 of the specification] to " Product name: Manufactured by Amoco Performance Products, Inc. in the U.S.” - 4/

Claims (5)

[Claims] (1) Dielectric loss εt in thermotropic liquid crystal polymer
A susceptor for a microwave oven, comprising a film or sheet filled with a filler having an δ of 0.8 or more. (2) The filler is thermotropic liquid crystal polymer 10
2. The susceptor for a microwave oven according to claim 1, wherein the susceptor is filled with 5 to 150 parts by weight relative to 0 parts by weight. (3) The filler is made of at least one type selected from barium titanate, calcium titanate, magnesium titanate, lanthanum titanate, barium zirconate, calcium zirconate, magnesium zirconate, and lanthanum zirconate. The susceptor for a microwave oven according to claim 1 or 2. (4) The susceptor for a microwave oven according to any one of claims 1 to 3, wherein the thermotropic liquid crystal polymer is a (co)polymer containing at least a monomer unit represented by the following general formula. General formulas ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (5) The susceptor for a microwave oven according to any one of claims 1 to 3, wherein the thermotropic liquid crystal polymer is a wholly aromatic polyester.