JP2525425B2 - Heat-resistant container and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydroxide and / or an oxide silicon compound containing silicon as a main component on at least the inner surface of a thermoplastic polyester resin layer having high crystallinity, or The present invention relates to a heat-resistant container having excellent heat resistance and stain resistance to foods formed by forming an inorganic coating layer of a metal oxide-containing silicon compound, and a method for producing the same.

[Prior Art] Conventionally, a method for obtaining a molded article having heat resistance by thermoforming and increasing the crystallinity using a sheet made of a thermoplastic polyester resin has been disclosed (Japanese Patent Publication No. 44-
5108, U.S. Pat.No. 3,960,807, JP Sho 50
-72950).

On the other hand, a container made of a highly crystalline thermoplastic polyester resin, a specific food, for example, filled with colored food such as curry, when heated in an oven or microwave,
Even if the dye in the food is transferred to the material of the container and the container is washed, the dye is adsorbed on the inner surface of the container, giving an aversion to repeated use, which is a major drawback.

Further, a coating composition containing colloidal silica or a silicone resin is known for the purpose of improving the abrasion resistance and other surface characteristics of the synthetic resin. For example, Japanese Patent Publication No. 52-39691.
No., published in Japanese Unexamined Patent Publication No. However, this coating composition has a composition different from that of the coating material of the present invention, and the coating film obtained contains an organic group and is inferior in heat resistance.

[Problems to be solved by the invention]

The present invention solves the above problems.
Heat resistance by forming a silicon compound containing silicon as a main component or a silicon compound containing a metal oxide as a coating film on at least the inner surface of the container without changing the properties of the thermoplastic polyester resin with increased crystallinity. And a heat-resistant container having excellent stain resistance to foods.

[Means for solving problems]

That is, the present invention has a resin layer having a crystallinity of 20% or more as a main component of a thermoplastic polyester resin, and at least the inner surface of the resin layer is a silicon-containing hydroxide and / or silicon oxide. A heat-resistant container comprising an inorganic coating layer of a compound or a silicon compound containing a metal oxide.

Further, according to the present invention, as a method for producing the heat-resistant container, the crystallinity is a main component of at least the inner surface of a container made of a resin composition containing a thermoplastic polyester resin of 20% or more as a main component In order to form an inorganic coating layer (A) of a silicon compound comprising a hydroxide and / or an oxide or a silicon compound containing a metal oxide, a solution of a metal alcoholate compound as a raw material for (A) and / or a polysiloxane A colloidal solution of a compound, wherein at least one of a hydroxy group, an alkoxyl group and an alkyl group is bound to the end of the polysiloxane compound, and a hydroxyl group and / or an alkoxyl group are bound simultaneously in the presence of the alkyl group. The colloidal solution (B) of (A) is applied by a method such as brushing, spraying or direct dipping, and heated (A). Method for producing a heat-resistant container, characterized in that machine coating layer crystallinity are formed in more than 20% of the thermoplastic polyester resin layer surface is provided.

〔Example〕

 The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a heat-resistant container in which a silicon compound coating layer 1 is formed only inside a thermoplastic polyester resin layer 2 having an increased crystallinity, and FIG. 2 shows a thermoplastic polyester resin layer 2 having an increased crystallinity. FIG. 3 is a cross-sectional view of a heat-resistant container having a silicon compound coating layer 1 formed on both sides thereof.

The resin used in the thermoplastic polyester resin layer 2 of the present invention has a crystallinity of 20% or more, preferably 20 to 50% in a range in which impact strength does not significantly decrease, and the crystallinity is In, it can be expressed by P _c = 1.47g / cm ^3, and P _a = 1.331g / cm ^3, thermoplastic value 100 times the X determined from the density P of Porieshiteru used.

The thermoplastic polyester resin, for example, phthalic acid, isophthalanol acid, terephthalic acid, maleic acid,
Saturated polybasic acids such as succinic acid and ethylene glycol, diethylene glycol, glycerin, trimethylpropane,
1 shows a synthetic resin obtained by an ester bond with a polyhydric alcohol such as 1,4-cyclohexanedimethanol. Further, this synthetic resin may be mixed with a crystal nucleating agent, a stabilizer, a lubricant, a pigment, another synthetic resin or the like. When such an additive is added, the crystallinity of the resin must be corrected for the specific gravity which naturally changes depending on the additive in the above-mentioned formula.

The thickness of the thermoplastic polyester resin sheet is
Although it is not particularly limited, it is preferably in the range of 100 to 2,000 μm, for example, to the extent that the contents are not deformed more than necessary.

The inorganic coating film of a silicon compound or a metal oxide-containing silicon compound (hereinafter referred to as a silicon compound) formed on the thermoplastic polyester resin layer of the present invention is a hydroxide and / or an oxide containing silicon as a main component, For example, a compound represented by the following general formula and / or an activated polysiloxane compound colloid can be formed as an inorganic coating layer by a reaction as shown in a specific example.

General formula: M (OR) _n (Formula 1) M (OR) _n · M ′ (OR) _m (Formula 2) RM (OR ′) _n-1 (Formula 3) (where M is silicon and M ′ is titanium) , Zirconium, etc., R is hydrogen and / or an alkyl group having 1 to 8 carbon atoms,
R'is an alkyl group having 1 to 8 carbon atoms,
Each of the above compounds has at least one alkoxyl group, n is an integer corresponding to the valence of M, and n is an integer corresponding to the valence of M '. ) Specific example: Si [OCH (CH ₃ ) ₂ ] ₄ + 4H ₂ O → Si (OH) ₄ +4 (CH ₃ ) ₂ CHOH Si (OH) ₄ → SiO ₂ + 2H ₂ O Polysiloxane that constitutes the inorganic coating material The colloid of the compound is obtained by treating the surface of a conventionally known colloidal silica to form an alkoxyl group and / or a hydroxyl group on the surface or at the terminal of polysiloxane, and the compound represented by the above formulas (alkoxyl group and / Hydroxyl groups) are activated colloidal particles. The particle size of the colloid is generally about 0.1 to 1 μm. Such a polysiloxane compound is represented by the following formula, for example.

In the formula, R is hydrogen and / or an alkyl group having 1 to 8 carbon atoms, and at least a part of O is an alkoxyl group. In the formula, the skeleton of the polysiloxane in the parentheses is schematically represented two-dimensionally in the above formula, but it is not necessarily two-dimensional and may be linear or three-dimensional.

In the silicon compound raw material of the present invention, the composition ratio of the metal alcoholate compound and the colloid of the polysiloxane compound is not particularly limited, but a weight ratio of about 82:18 to 50:50 is preferable. If the polysiloxane colloid is small, it is difficult to obtain a thick inorganic coating film, and if it is too large, pinholes and cracks are likely to form in the coating film, so that the above composition range is preferable.

Furthermore, the silicon compound raw material of the present invention is a water-containing alcoholic solution of a metal alcoholate compound.

Water-containing alcoholic solution of metal alcoholate compound 100
30 parts by weight or less of titanium oxide, zirconia silicate, nickel powder, copper oxide, chromium oxide, manganese oxide, inorganic filler such as alumina, colorant, diluent solvent, curing accelerator, and other additives May be entered. The diluting solvent is isopropyl alcohol, ethyl cellosolve, and the curing accelerator is not particularly limited as long as it accelerates the hydrolysis of the metal alcoholate, but various organic acids and the like are suitable.

To form a coating film on the resin layer, after degreasing treatment with an alkaline degreasing agent or the like, a brush, spraying and direct dipping are attached to the resin layer at a temperature of 70 to 220 ° C., preferably 120 to 20.
By heating in an oven or an oven at a temperature of 0 ° C., more preferably 160 to 180 ° C. for 5 to 30 minutes, the above reaction occurs and a silicon compound is formed in the resin layer. If the drying temperature is lower than 70 ° C, it takes a long time to dry, which is not preferable, and if the drying temperature exceeds 220 ° C, the drying speed of the coating film surface becomes faster,
It is not preferable because the coating film becomes foamy and pinholes are easily generated, and further the resin is crystallized, which deteriorates the entire container. Accordingly, the heat treatment conditions of 160 to 180 ° C. for 5 to 30 minutes adopted in the present invention are those which are uniquely adopted because of the high heat resistance of the thermoplastic polyester resin having a crystallinity of 20% or more, Moreover, the productivity of the coating film is made extremely excellent in combination with the selection of the coating material of the present invention.

The coating thickness of the silicon compound is not particularly limited as long as it does not cause pinholes, but from the viewpoint of economy, it is 2 to 20.
A film thickness of about μm is adopted. Here, in the present invention, a relatively thick coating film can be easily formed. It is considered that one of the reasons is that the thermoplastic resin base material having a crystallinity of 20% or more and the volume change of the silicon compound coating film in the coating film forming process act appropriately.

The present invention also includes the feature that a thicker coating film can be more easily formed by mixing an inorganic filler typified by titanium oxide.

The method for obtaining the heat-resistant container of the present invention is carried out by thermoforming the thermoplastic polyester resin layer 2 containing a crystal nucleating agent or the like in advance in a molding die which is previously held at a high temperature in vacuum forming, pressure forming and vacuum / pressure forming machine, A container is obtained by increasing the crystallinity of the thermoplastic polyester resin to 20% or more, and further a silicon compound coating layer 1 is formed at least on the inner side where food is filled to obtain a heat resistant container with dye resistance. be able to. Similarly, in the heat-resistant container of the present invention, a raw material sheet of a thermoplastic polyester resin is coated with a silicon compound raw material in advance, heated in a furnace, and then heat-formed by vacuum forming, pressure forming or vacuum / pressure forming machine. A method of obtaining a container, or a method of coating a raw silicon sheet with a silicon compound raw material, forming by vacuum forming, pressure forming and vacuum / pressure forming machine, and heating in a furnace to obtain a heat-resistant container,
Either can be obtained.

Thus, the coating film made of a hydroxide and / or oxide containing silicon as the main component, which is formed on the thermoplastic polyester resin layer according to the present invention, is an inorganic coating film and does not substantially include an organic machine. It has high hardness (wear resistance) and high heat resistance, and has no affinity for dyes such as food,
It is most suitable for the purpose of the present invention to provide a heat-resistant container having excellent heat resistance and stain resistance to foods.

In FIG. 1, the silicon compound forming coating layer 1 is only on the inner side, and if necessary, another heat resistant resin or the like can be adhesively laminated on the outer side of the thermoplastic polyester resin layer 2. Further, FIG. 2 is an example in which the coating layer 1 of the silicon compound is formed both inside and outside the resin layer of the container.

The heat-resistant container obtained in the present invention is mainly used for food, and is used for cooking in an oven, a microwave oven, etc., but as described above, it is particularly effective for heating a specific food containing a pigment. .

In the following examples and comparative examples, the evaluation of the heat resistance of the container and the food dye transferability was as follows.

Heat resistance: left in an oven at 180 ° C for 10 minutes, taken out, and visually inspected the deformed state of the container.

○: No deformation △: Deformation was observed, Food dye migration: After filling the container with curry roux and heating in a microwave oven for 3 minutes, the contents were taken out and the container was washed with water, and then the degree of coloring was measured. It was judged visually.

◯: Dye is not transferred and is good. X: Dye is clearly transferred.

Examples 1 to 3 Extruded wall thickness of thermoplastic polyester resin (trade name: PET 5132, manufactured by Eastman Chemical Co., Ltd.) to enhance crystallinity
A sheet of 500 μm was prepared, and a 120 × 60 × 20 mm container was formed by using the sheet with a vacuum / pressure forming machine. Next, place the container in an alkaline degreasing agent for aluminum (Koei Industry Co.
It was immersed in a 5% aqueous solution of PS-500A (product name) manufactured at room temperature for 1 hour, washed with water and dried by heating to degrease. Then, by air spraying on the inside of the container (food filler), as a metal alcoholate compound solution in which the main coating film after coating is SiO ₂ , manufactured by Nichiban Kenkyusho Co., Ltd., trade name Glasca G90 (solid content 1
8%), and dried in an oven at 180 ° C. for 20 minutes to form a 10 μm silicon compound coating layer.

When the physical properties were measured, good results were obtained regarding the heat resistance and the dye transferability of foods. The measurement results are shown in the table.

Example 4 The same thermoplastic polyester resin as in Example 1 was extruded,
A sheet having a wall thickness of 700 μm was prepared, and a 120 × 60 × 20 mm container was formed by using the sheet with a vacuum / pressure forming machine.

Next, using a spray gun (Iwata W-71 type, nozzle aperture 1.0 mmφ, pressure 2.0 kg / cm ³ ) inside the container by air spray, the coating film main component becomes SiO ₂ · TiO ₂ after coating. The same operation as in Example 1 was carried out except that a glass alcohol G1100A (solid content 51%, white liquid), manufactured by Nichiban Kenkyusho Co., Ltd. was applied as the metal alcoholate compound solution. When the physical properties were measured, good results were obtained regarding the heat resistance and the dye transferability of foods.
The measurement results are shown in the table.

Example 5 The same procedure as in Example 1 was applied to the inside of a degreased thermoplastic polyester container with a brush to apply Glasca G90 (trade name, manufactured by Nichiban Kenkyusho Co., Ltd.) to a concentration of about 50 g / m ^2. The same operation as in Example 1 was performed except for the above. When the physical properties were measured, good results were obtained regarding the heat resistance and the dye transferability of foods. The measurement results are shown in the table.

Example 6 A degreased thermoplastic polyester container produced by the same method as in Example 1 was dipped in a solution of Glasca G90 solution manufactured by Nichiban Kenkyusho Co., Ltd., dried at room temperature for about 6 hours, and then again. After the immersion, the same operation as in Example 1 was performed, except that it was dried in an oven at 180 ° C. for 30 minutes to form a silicon compound coating film layer of about 20 μm on the entire surface of the container. When the physical properties were measured, good results were obtained regarding the heat resistance and the dye transferability of foods. The measurement results are shown in the table.

Comparative Examples 1-2 Only the thermoplastic polyester resin of Example 1 was extruded, 50
A 0 μm sheet was obtained. Using the sheet, a container having the same shape as in Example 1 and not coated was prepared, and the heat resistance and the dye transferability of food were measured. The measurement results are shown in the table.

[Effects of the Invention] As described below, according to the present invention, it is possible to obtain a heat-resistant container in which the migration resistance of food dyes is improved while maintaining the heat resistance of the thermoplastic polyester resin having an increased crystallinity.

[Brief description of drawings]

 1 and 2 are sectional views of the heat-resistant container of the present invention. 1 ... Silicon compound coating layer, 2 ... Thermoplastic polyester resin layer.

Claims (2)

(57) [Claims] 1. A resin layer containing a thermoplastic polyester resin having a crystallinity of 20% or more as a main component, and a silicon containing hydroxide and / or an oxide containing silicon as a main component on at least the inner surface of the resin layer. A heat-resistant container comprising an inorganic coating layer of a compound or a silicon compound containing a metal oxide. 2. A silicon compound having a hydroxide and / or an oxide having silicon as a main component on at least the inner surface of a container made of a resin composition having a thermoplastic polyester resin having a crystallinity of 20% or more as a main component. Alternatively, a metal alcoholate compound solution and / or a colloidal solution of a polysiloxane compound, which is a raw material of (A), for forming an inorganic coating layer composed of a metal oxide-containing silicon compound (A), the polysiloxane At least one of a hydroxyl group, an alkoxyl group, and an alkyl group is bonded to the terminal of the compound, and in the presence of the alkyl group, a colloidal solution (B) of a polysiloxane compound in which the hydroxyl group and / or the alkoxyl group are simultaneously bonded is attached and heated. Therefore, the inorganic coating layer (A) is formed on the surface of the thermoplastic polyester resin layer having a crystallinity of 20% or more. Method of manufacturing heat resistant container to be collected.