JP2011006713A - Cold storage material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold storage material that requires a short cooling time for freezing and has a long effective cold insulation time.SOLUTION: The cold storage material is obtained as follows: paste of water-soluble carboxymethylcellulose at a concentration of 10-60% in water is irradiated with radiation to cause a crosslinking reaction to gelate the carboxymethylcellulose; the gelated carboxymethylcellulose is dried, and the dried gel of the carboxymethylcellulose is pulverized to the size of 0.5 mm diameter; and the cold storage material having a freezing point of -5°C is obtained by adding 0.5-10% of the dried gel to saline of a concentration of 1-15% and mixing.

Description

  The present invention relates to a cold storage material used for cooling and cold storage during storage or transportation of foods and pharmaceuticals.

  As a conventional cold storage material (cool storage agent), an aqueous solution of an inorganic salt such as sodium chloride, ammonium chloride or magnesium chloride, an aqueous alcohol solution such as methanol or ethanol, or a known gelling agent is added to a water-soluble polymer. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 11-257814

  However, the above-described conventional cold storage material has a problem that the time required for freezing is long and the effective time for cooling is short. As a result, for example, when used for refrigeration of a luggage room of a truck that transports fresh products over long distances with a schedule that leaves early in the morning and returns late at night, the cold storage material used on the day is returned and the next morning It is difficult to freeze before departure, and the cooling effect is significantly reduced during the transportation of one day, so it is not suitable for long-distance transportation of such fresh products. There is a demand for a cold storage material having a short cooling time required for freezing and a long effective cold keeping time.

  An object of the present invention is to solve the above problems.

  Therefore, the cold storage material of the present invention is obtained by irradiating a paste-like polysaccharide derivative with radiation to cause a crosslinking reaction to gel the polysaccharide derivative and drying the gelled polysaccharide derivative. The dried gel is mixed with 1-15% saline.

  Specifically, according to the present invention, a water-soluble carboxymethylcellulose paste having a concentration of 10 to 60% in water is irradiated with radiation to cause a crosslinking reaction to gel the carboxymethylcellulose, and the gelated carboxymethylcellulose. The dried carboxymethylcellulose gel is pulverized to a size of 0.5 mm diameter, and the dry gel is added to 1 to 15% saline and mixed by adding 0.5 to 10%. A cold storage material having a freezing point of 5 ° C. is provided.

  According to the present invention, since a polysaccharide derivative that has caused a crosslinking reaction is used, the cooling time required for freezing is short and the effective cooling time is long.

The graph which shows the temperature transition at the time of cooling of the cool storage material by an Example The graph which shows the temperature transition at the time of the cold storage of the cool storage material by an Example Graph showing temperature transition during cooling of commercial regenerator materials Graph showing temperature transition during cooling of commercial regenerator materials

Embodiments of the regenerator material according to the present invention will be described below with reference to the drawings.
In recent years, from the viewpoint of safety and environmental conservation, recycling materials that do not burden the environment that can be reused as post-use resources have been demanded in various fields, and cold storage materials are no exception, so plants are used as materials. Processed products are attracting attention, and a typical material is a polysaccharide derivative such as cellulose.

  When radiation is directly applied to cellulose, decomposition does not occur and a crosslinking reaction does not occur, so it does not become a hydrogel, but is a carboxymethyl cellulose derivative (hereinafter referred to as CMC) that has been processed so as to dissolve in water. ) Is dissolved in water to prepare a paste having a high concentration of 10% or more (preferably 10 to 60%), and when the paste-like CMC is irradiated with radiation, a crosslinking reaction occurs and gels.

The CMC dried gel can be obtained by drying the gelled CMC to remove moisture.
This CMC dry gel has a characteristic that 1 gram absorbs 400 times as much water when put on pure water, and 100 times as much water in physiological saline.

  The cold storage material in this example is manufactured by mixing CMC dry gel having such water absorption characteristics with saline, and the dry gel used for this cold storage material is dissolved in water and has a concentration of 20%. The paste-like CMC prepared in this manner is most preferably dried by irradiating it with radiation of about 5 kGy, and the one pulverized to a size of about 0.5 mm is most suitable for processing without fusion between polymers.

  The cold storage materials in this example are those for refrigeration and those for freezing. For refrigeration, freezing point is obtained by adding 0.5% to 10% of CMC dry gel to saline and mixing well. A 5 ° C. regenerator material can be produced, and by adding 1 to 20% propylene glycol thereto, a freezing regenerator material having a freezing point of −27 ° C. can be produced.

  A preferable composition as a cold storage material for refrigeration is a composition in which the concentration of the pulverized CMC dry gel is adjusted to 1% to 5% in 1% to 5% saline. It is most effective to set the concentration of the dry gel to about 3%.

  In addition, as a refrigerating material for freezing, it is preferable to add 10% to 20% of propylene glycol after adding 1% to 5% of CMC dry gel to 5% to 15% saline.

A comparative example of the freezing and cooling effect of the refrigeration storage material and the commercial refrigeration storage material according to this embodiment will be described.
A cold storage material of this example made by adding 3% of CMC dry gel to 1% saline and a commercial cold storage material (a polymer water-absorbing polymer dissolved in water and added with viscosity) at −35 ° C. It cooled in the fan type freezer for 10 hours, and measured the temperature transition of each cool storage material.

1 and 3 are graphs showing the temperature transition of the regenerator material at this time, in which each temperature is represented on the vertical axis and time is represented on the horizontal axis.
1 and 3, A is the temperature transition in the freezer, B in FIG. 1 is the temperature transition of the regenerator material according to this embodiment, and C in FIG. 3 is the temperature transition of the commercial regenerator material.

  The cold storage material of the present embodiment used here is 12 pieces put in a container, and the commercial cold storage material is 10 pieces put in a container, but the internal capacity is about the cold storage material of this embodiment. It was 9,042.6g, and the commercial cold storage material was about 9,732.7g, so that a large difference was not caused.

  As a result of the measurement, the commercially available regenerator material cannot reach −10 ° C. even if it is cooled for 10 hours as shown in FIG. As shown in FIG. 1, the temperature reached −10 ° C. in about 5 hours and 25 minutes, and the time required for freezing was found to be less than half that of a commercially available cold storage material.

  Next, seven of the regenerator materials of this example cooled for 10 hours in this way are contained in a styrene foam BOX (box) having an internal dimension of approximately 500 mm in length, 900 mm in width, and 480 mm in depth, and a plate thickness of about 250 mm. Then, the temperature was changed for 15 hours from 9 o'clock to 24 o'clock under the environment of the outside temperature with the lid covered, and the temperature change of the commercial regenerator material was measured under the same conditions.

The temperature inside the BOX when the cold storage material was added was the same as the outside air temperature.
FIG. 2 and FIG. 4 are graphs showing the temperature transition in each regenerator and BOX at this time, with the temperature on the vertical axis and the time on the horizontal axis (however, FIG. 4 is from 9:00 to 21:00) For 12 hours).

  B in FIG. 2 shows the temperature transition of the regenerator material according to the present embodiment, C in FIG. 4 shows the temperature transition of the commercial regenerator material, and in FIGS. 3 and 4, D is the average outside air temperature. In the case of measuring the cold storage material, it is 37.7 ° C., and in the case of a commercial cold storage material, it is 37.3 ° C.

Further, E represents the temperature immediately below each regenerator material, F represents the central portion of the BOX, and G represents the temperature transition at the bottom of the BOX.
In addition, from 9:00 to 18:00, the lid was opened 10 times every 2 minutes for 2 minutes.

  As a result of the measurement, in the commercial regenerator material, the temperature reached 0 ° C. in less than 4 hours after being put in the BOX as shown in FIG. 4, and the temperature rose to 8 ° C. in 11 hours. Moreover, the temperature of each part in the BOX did not drop to 0 ° C., but increased to about 10 ° C. in 11 hours.

  In contrast, as shown in FIG. 1, the cool storage material of this example kept the temperature at 0 ° C. or less until 9 hours passed after being put in the BOX, and 15 hours until the temperature rose to 8 ° C. Is needed. Further, the temperature of each part in the BOX reached 0 ° C. or less within 1 hour after putting the regenerator material, took about 4 hours to reach 0 ° C., and took 15 hours to reach 10 ° C.

As described above, the regenerator material of this example had a shorter cooling time required for freezing and a longer effective cool time as compared with a commercially available regenerator material.
As a result, the regenerator material of this example can save energy required for freezing and leads to improvement of work efficiency. The effect that it can be used is obtained.

  Moreover, since the cold storage material of the present embodiment is mainly composed of a cross-linked CMC dry gel and saline, it can be reused as a post-use resource and has an effect of not giving much load to the environment. can get.

  The cold storage material of the present invention has a short time required for freezing and a long effective time for cold storage. For example, a cargo vehicle that transports fresh food, frozen products, etc. over long distances on a schedule that leaves early in the morning and returns late at night. It is extremely effective as a cold storage material for refrigeration and freezing.

Claims (1)

A water-soluble carboxymethylcellulose paste having a concentration of 10 to 60% in water causes gelation of the carboxymethylcellulose by causing a crosslinking reaction by irradiation with radiation.
Dry the gelated carboxymethyl cellulose,
Grinding the dried carboxymethylcellulose gel to a size of 0.5 mm diameter,
A cold storage material having a freezing point of −5 ° C. obtained by adding 0.5 to 10% of the dry gel to 1 to 15% saline and mixing.