JP6595821B2 - Method for manufacturing resin tableware - Google Patents

Description

  The present invention relates to a method for producing a resin tableware that can be heated by a microwave oven.

  Conventionally, melamine resin compositions that can be heated by a microwave oven are known. For example, in a melamine resin composition for microwave ovens containing a melamine resin and an additive, the resin component contains 4 to 35% by mass of a tough melamine resin based on the total amount of the composition, and the composition is used as an additive. A melamine resin composition containing 7 to 35% by mass of polytetrafluoroethylene resin based on the total amount is known (see Patent Document 1).

JP-A-2015-121

  However, in the structure of Patent Document 1, a melamine resin composition is compression-molded, for example, a 120 mm diameter dish is molded only under molding conditions of a temperature of 160 ° C., a pressure of 20 MPa, and a molding time of 90 seconds. Although it conforms to the high frequency suitability test, there is a concern about the content of unreacted melamine resin remaining in the resin tableware, and there are concerns about the occurrence of cracks and discoloration caused by condensed water when heated in a microwave oven. It was a thing.

  Accordingly, the present invention solves such problems, and reduces the content of unreacted melamine resin remaining in the resin tableware, and prevents cracks caused by condensed water during heating of the microwave oven. It aims at providing the manufacturing method of the resin tableware which can prevent generation | occurrence | production and discoloration.

In order to solve the above problems, the resin tableware manufacturing method according to claim 1 of the present invention compresses a melamine-based resin molding material having a dielectric constant of 4 to 6 to which an additive is added into a tableware shape. The method includes a molding step for forming a molded product having a thickness of 2.6 to 3.2 mm, and a heat treatment step for subjecting the molded product to a reheating treatment.

  Moreover, the manufacturing method of the resin tableware of Claim 2 of this invention is a manufacturing method of the resin tableware of Claim 1, Comprising: The pre-heat treatment process is performed to the said melamine-type resin molding material.

Moreover, the manufacturing method of the resin tableware of Claim 3 of this invention is a manufacturing method of the resin tableware of Claim 1 or Claim 2 , WHEREIN: The said molded article shall be for microwave oven heating. It is.

  In the method for producing resin tableware according to the present invention, since the re-heat treatment is performed on the molded product after compression molding, the content of unreacted melamine resin remaining in the resin tableware is reduced, and the microwave oven is heated. Occurrence of cracks and discoloration due to condensed water at the time can be prevented.

  Hereinafter, the manufacturing method of the resin tableware in embodiment of this invention is demonstrated. In this manufacturing method, a melamine-based resin molding material having a dielectric constant of 4 to 6 to which an additive is added is compression-molded into a tableware shape and then subjected to a reheating treatment. Thereby, the content of unreacted melamine resin remaining in the resin tableware can be reduced, and the occurrence of cracks and discoloration due to condensed water during heating of the microwave oven can be prevented. The resin tableware includes a dish, a tray, a cup, a cup, a small bowl, a bowl, a bowl, a lunch box, a sealed container, and the like.

  Examples of the melamine resin used in the melamine resin molding material of the resin tableware according to the present invention include, for example, methylol melamine resin, methylol melamine-phenol co-condensation resin, methylol melamine-urea co-condensation resin, and methylol melamine. -Synthetic resins obtained by cocondensation of triazines such as epoxy cocondensation resins with formaldehyde can be used, but are not limited thereto. Specifically, for example, powdered melamine formaldehyde condensation polymerization resin (such as “CP9012” manufactured by Panasonic Corporation) can be used.

  The additive is not particularly limited as long as it is a resin material that can lower the dielectric constant of the main melamine-based resin molding material. By blending the additive, microwave high frequency suitability can be improved, and particularly by blending a silicone elastomer, heat resistance and microwave durability can be improved, which is effective.

  In addition, the melamine-based resin molding material can further contain other components within a range not impairing the effects of the present invention. For example, organic fillers such as α cellulose and melamine resin, inorganic fillers such as barium sulfate, hardeners such as phthalic anhydride, mold release materials such as stearic acid, zinc stearate, and carboxyl group-containing polyolefin, plasticizers, colorants, etc. Can be used.

  The melamine-based resin molding material to which such an additive is added can be prepared as follows. First, the above melamine resin, additives, and other components are blended, and uniformly pulverized and mixed with a ball mill. Next, a granular melamine-based resin molding material can be prepared by making the mixture into a plate-like body using a roll and pulverizing the plate-like body. Further, the mixture can be prepared by heating and kneading with a kneader or roll, solidifying by cooling, and pulverizing the obtained solidified product, thereby preparing a granular melamine resin molding material.

  And the said melamine-type resin molding material is shape | molded by the compression molding method, and is set as resin tableware. In the melamine resin molding material, for example, a melamine resin material MM− having a dielectric constant of 4 to 6, in which silicone elastomer, α-cellulose and melamine resin are blended as organic filler, and barium sulfate is blended as inorganic filler. K150402 (manufactured by Panasonic Corporation) is used.

  In the compression molding method, for example, the melamine-based resin molding material is supplied to a mold heated to about 160 to 175 ° C. and molded by pressing for a predetermined time. At the time of molding, primary molding, secondary molding, and the like can be performed in a plurality of times. For example, in the primary molding, 20 MPa is applied for 70 seconds, in the secondary molding, 20 MPa is applied for 15 seconds, and in the tertiary molding, 20 MPa is pressurized for 30 seconds. Then, a semi-molded product is taken out from the mold, and finish processing such as removing burrs is performed to obtain a molded product.

  At this time, in Examples 1 to 4 shown in Table 1 below, the classification is made according to the combination of the preheating process in which heat treatment is performed at the stage of the melamine-based resin molding material and the reheating process in which heat treatment is performed at the stage of the molded product. ing.

  In the pre-heat treatment step, the melamine-based resin molding material is heated in advance by a heater having a capacity of 5 kW before compression molding. The heating time is appropriately adjusted according to the thickness of the molded product after molding, and the heating time is 50 for a melamine-based resin molding material for molding a molded product having a thickness of 2.6 to 3.4 mm. 70 seconds. In the reheat treatment step, the molded product after compression molding is reheated at a treatment temperature of 120 ° C. and a treatment time of 10 hours.

  Moreover, about each test body of Example 1 to Example 4, it tested based on the microwave high frequency suitability test prescribed | regulated to JISS2029. In this test, a test specimen is placed on a tray of a microwave oven and heated at a high frequency output of 750 W for a predetermined time. Since the JIS standard does not have a prescribed value for the heating time according to the high frequency output 750 W, the heating time according to the high frequency output value according to the JIS standard was calculated and tested. In this test, the safety factor was 10%, the conditions were stricter than the JIS standard, and the heating time was 190 seconds.

  And the presence or absence of the spark from a test body at the time of a heating and the presence or absence of the abnormality which becomes a fault on use were examined visually. Moreover, about the test body by which abnormality etc. were not seen after 190 second of heating time, the test which continues a heating until a crack was discovered was done.

  In Table 1 below, for the test specimens, there were no abnormalities such as sparks, and no abnormalities were observed after a heating time of 190 seconds, and “No” was observed when abnormalities were observed. . Moreover, about the conformity goods which cleared heating time 190 second, the heating time when a crack is discovered is shown.

  The contents of the abnormality are easily heated by the condensed water generated when the unreacted melamine resin undergoes a condensation reaction, and further the cracks caused by the condensation water evaporating and jumping out of the resin, and the specimen being heated to a high temperature. The cellulose and the like contained in the color change.

  In addition, the surface temperature of the central portion at the bottom of each specimen when the specimens of Examples 1 to 4 were placed on the tray of the microwave oven and heated at a high frequency output of 750 W for 60 seconds was separately measured.

  As shown in Table 1, in Example 2 and Example 4 where at least reheating treatment was performed, the microwave oven was excellent in high frequency suitability. Moreover, in these Examples, Example 4 which performed the pre-heat treatment was able to lengthen the elapsed time until crack generation.

  On the other hand, for the specimens having a plate thickness of 3.3 mm and a plate thickness of 3.4 mm in Example 2 and Example 4, the heating time of 190 seconds was not cleared, and the internal heat during heating increased with the increase in thickness. It was not released, and cracking and discoloration due to condensed water were observed. That is, it was confirmed that the test pieces having a plate thickness of 2.6 to 3.2 mm in Example 2 and Example 4 were resin tableware suitable for a microwave oven.

  Moreover, also about the surface temperature in each test body, in Example 2 and Example 4 which performed the reheating process at least, it was confirmed that surface temperature became low, and the elapsed time until crack generation was lengthened in connection with this. It was confirmed that it was possible.

  Further, separately from the above test, the microwave oven high frequency suitability test and the microwave oven durability test specified in JIS S 2029 were performed on the specimens having a plate thickness of 2.8 mm and a plate thickness of 3.0 mm in Example 4, and both It was confirmed that the resin tableware was suitable for the test.

  As described above, according to the resin tableware manufacturing method according to the present invention described above, the content of unreacted melamine resin remaining in the molded product is reduced by at least the reheating treatment step after compression molding, and the microwave oven Generation of cracks and discoloration due to condensed water during heating can be prevented.

  Furthermore, it is needless to say that a part of the process can be omitted and a part of the process can be extracted.

Claims (3)

A molding step in which a melamine-based resin molding material having a dielectric constant of 4 to 6 to which an additive has been added is compression-molded into a tableware shape to obtain a molded product having a thickness of 2.6 to 3.2 mm ;
A heat treatment step for reheating the molded article;
The manufacturing method of the resin tableware characterized by including.   The manufacturing method of the resin tableware of Claim 1 which performs a pre-heat treatment process on the said melamine-type resin molding material. The said molded article is a manufacturing method of the resin tableware of Claim 1 or Claim 2 used for microwave oven heating.