JPH02242047A - Exothermic characteristic evaluation method for throwaway portable pocket heater's raw materials - Google Patents

Abstract

PURPOSE:To rate accurately the characteristic of endothermic raw materials for a throwaway pocket heater by blending an endothermic raw material for a throwaway pocket heater in a container, such as a glove box replaced with nitrogen, and then trying to fill an insulated reaction container, which is arranged to control the amount of air supply, with said raw material, and inserting a direct temperature measurement sensor into the raw material. CONSTITUTION:An attempt is made to take out an endothermic raw material for a throwaway pocket heater to be measured in an enclosed container replaced with nitrogen or blend the endothermic raw material 6 so that it may not react prior to measurement. Then, an air pump 1, a flow rate controller 2, and a flow meter 5 are installed so that the amount of air may be controlled either in automatic or manual mode, moreover, a reaction container 4 covered with an insulation material 3 is filled with the endothermic raw material 6. The container 4 is also designed so that air may be supplied to the endothermic raw material 6 by way of an air supply pipe 7 where a temperature sensor 7 is inserted into the endothermic raw material directly so that the endothermic characteristic may be measured and evaluated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the heat generating properties of a disposable body warmer material that generates heat by the chemical reaction of the contained ingredients without applying external energy such as fire or electricity during use. This invention relates to a method for easily and accurately evaluating

[Prior Art] Since many disposable body warmers have come to be distributed in the market and are mainly used as body warmers, standardization has been carried out and JIS was established in 1985. The conventional heat generation characteristic evaluation method is described in JIS S4]00. The measurement method is shown in Figure 1, and the test conditions (
1) Ambient temperature 5±5℃, (2) Ambient humidity 55-70%,
(3) Under conditions of no wind with a wind speed of 0.5 m/s or less, the outside of the stainless steel hot water circulation tank 12 at 35°C is insulated with expanded polystyrene lO, and the polypropylene plate 1 with a thickness of 1 mm is
After stacking the 7 sheets of 1 and laying 2 sheets of gauze 14 on top of this, placing the disposable body warmer 9 in the same way as when using it,
In this method, three sheets of flannel 13 are covered and a temperature sensor 8 is set between a disposable body warmer and gauze, and the heat generation characteristics are measured.

[Problem to be solved by the invention] The method for measuring heat generation characteristics according to JIs is standardized based on the assumption that disposable body warmers are actually used on the human body, so it is not nearly sufficient to evaluate the usage characteristics. However, since measuring temperature through a breathable packaging material also detects the influence of the packaging material's air permeability and ventilation pattern, it has not been sufficient to evaluate the pure characteristics of the heat generating material. In addition, there is a problem that the contact conditions between the disposable body warmer and the temperature sensor are not necessarily the same, resulting in large variations in the measured values, and JIS specifies that the number of samples for one sample is 10.

As a result, the reaction time of disposable body warmers at one time is approximately 20
Because it takes more than an hour, it takes almost a whole day to measure.
If the system does not have many measuring devices, there are problems such as the fact that it takes a lot of time to evaluate the characteristics.

In view of this, the present invention provides a method for accurately evaluating the characteristics of the heat generating material of a disposable body warmer. That is, the present invention provides a method for directly measuring the exothermic characteristics of a exothermic material configured to control and adjust factors that affect exothermic reactions.

[Means for Solving the Problems] The present invention was made as a result of various experiments and studies on the heat generating properties of heat generating materials and the factors that affect them. After the materials are mixed in a glove box-like container purged with nitrogen, they are filled into an insulated reaction container with adjustable air supply, and a temperature sensor is inserted directly into the materials. This is a method for evaluating the heat generation characteristics of disposable hand warmer materials.

That is, in the present invention, the heating material for disposable body warmers to be measured is taken out from the packaging material of the body warmer in a closed container purged with nitrogen to prevent it from reacting before the measurement, or after the heating material 6 is mixed with the heating material, as shown in FIG. As shown in , an air pump 1, a flow rate regulator 2, and a flow meter 5 are installed so that the air supply amount can be adjusted either manually or automatically, and a heat insulating material 3 is installed.
The reaction vessel 4 covered with the heat-generating material 6 is filled with the heat-generating material 6, air is supplied to the heat-generating material 6 through the air supply pipe 7, and the temperature sensor 8 is directly inserted into the heat-generating material to measure the heat-generating characteristics. , to be evaluated.

Here, it is appropriate to use a material with low thermal conductivity such as styrofoam for the reaction vessel, and the insulating material is composed of a material with low thermal conductivity and low heat capacity, such as ceramic wool, wrapped around the reaction vessel. Alternatively, the same effect can be obtained even if the structure is constructed using vacuum insulation.

[Action] Iron, oxygen, and moisture are essential elements for the oxidation exothermic reaction of iron powder to proceed. Since iron and water are included in the heat-generating material, we investigated the effect of the amount of air supply on the heat-generating characteristics.

For that, air pump and flow! ;1 A regulator was installed to adjust the oxygen supplied to the heat generating material, and the influence of the air supply amount on the heat generating properties of a commercially available disposable hand warmer material was measured. The results are shown in Figure 3. It was confirmed that by increasing the air supply amount from 0.5 fl/+in to 1.017 ain, the rise time was shortened, the maximum temperature was high, and the heat generation duration was shortened, and the effect of the air supply amount on the heat generation characteristics was It had a big impact. This is thought to be because the oxygen supply is rate-limiting to the disposable hand warmer material, and it is essential to adjust the air and oxygen supply amounts in order to investigate the heat generation characteristics.

Regarding the heat insulation effect of the reaction container, we measured the exothermic characteristics by installing a Styrofoam container in an atmosphere of 20 ± 1 °C without insulation, and when using ceramic wool at 30 mm.
Figure 4 shows the heat generation characteristics when insulated with a thickness of . As a result, when the reaction vessel was insulated, heat radiation from the reaction vessel was reduced, the maximum temperature increased, and the duration of heat generation became longer. This minimizes loss due to heat radiation,
In order to accurately measure exothermic characteristics, it is necessary to insulate the reaction vessel.

Figure 5 shows the change in heat generation properties when the heat generating materials are mixed in a nitrogen purged container and when mixed in the atmosphere. , the duration became shorter. This is thought to be because the exothermic material reacted before the heat generation measurement, resulting in a shorter duration.In order to accurately evaluate the exothermic properties of the exothermic material, the exothermic material should be mixed in a nitrogen-purged container. It is essential to conduct and fill the reaction vessel.

Since air is supplied to the surface of the heat-generating material, the insertion position of the temperature sensor into the heat-generating material has a large effect on the measurement of heat generation characteristics.
Temperature sensors were inserted at three locations: +m position, 25no+ position at the center of the flap, and 45mm position near the bottom, and the heat generation characteristics were measured. As a result, as shown in Figure 6, when inserted at a position 5fflln from the surface, the temperature rose in a short time, but the maximum temperature was low and the duration was short. The fever ended. Furthermore, when the temperature sensor was inserted to the bottom of the heat generating material, the heating time was longer and the maximum temperature was almost the same as when inserted at the 25IIIffl position, but the duration was shorter.

The cause of this was that the exothermic material was taken out and observed after the reaction characteristics were evaluated, and as a result, there was some unreacted exothermic material remaining at the bottom of the reaction vessel, resulting in a short duration.The typical characteristics of the exothermic material were measured and evaluated. In order to do this, the temperature sensor must be inserted approximately in the center of the reaction vessel.

[Example] (Example 1) In the method for evaluating the characteristics of a heat-generating material according to the present invention, which is configured with an apparatus having the shape and specifications shown in Table 1, a reaction vessel with a thickness of 1
Made of styrofoam with an outer diameter of 40 mm and a height of 70 mm.
The heat conductivity coefficient around the hole is 0.11 kc.
coated with ceramic wool of al/m/h/°C to a thickness of 30 mm, pressure of 2 kg/cm'', 10 IL/min
After filling 50g of a commercially available disposable body warmer material and a material containing iron powder with a particle size of 50JJI11 with excellent reactivity in a container that was purged with nitrogen for 10 minutes, the container was heated at 20°C.
It is installed in a constant temperature layer, and the air supply amount is 0.5 j! /mi
A thermocouple with a diameter of 1 mm+ was inserted into the center of the heat generating material to measure the heat generating properties.

Here, the supplied air was supplied from a cap installed at the opening of the reaction vessel, and at the same time a discharge part was provided so that it could be discharged.

For comparison, the heat generation characteristics of the same material were also measured using the JIS method. As a result, as shown in Figure 7, almost no change in the heat-generating material could be detected using the JIS method, but according to the method of the present invention, the maximum temperature of the heat-generating material with improved reactivity was higher; The time has become shorter and the duration has become shorter.

(Example 2) In the method for evaluating the characteristics of a heat-generating material according to the present invention, a styrene foam with a thickness of 1 mm was used as the reaction vessel, which was constructed with an apparatus having the same shape and specifications as in Example 1, and an outer diameter of 4011Iff was used.
It is molded to a height of 70 mm, and the area around it has a thermal conductivity coefficient of 0.
11kcal/m/h/30 with ceramic cool at ℃
Coated to a thickness of 10 mm, a pressure of 2 kg/cm2, 10
In a container purged with nitrogen at a rate of 1/min for 10 minutes, a particle size of 50 μm, which has excellent reactivity with commercially available disposable hand warmer materials, was heated.
After filling each material with 50 g of iron powder mixed with m, it was placed in a constant temperature layer at 20°C, and the air supply amount was set at 0.5 Il.
The flow rate was adjusted to 1.0 IL/min and 1.0 IL/win using a control valve, and a thermocouple with a diameter of 11 was inserted to the center of the heat generating material to measure the heat generation characteristics. It is supplied from a cap installed in the opening, and a discharge part is also provided at the same time so that it can be discharged.

Figure 8 shows the heat generation characteristics. According to the method of the present invention, when the air supply amount was increased to 1.01 L/min, the maximum temperature became higher and the temperature rising time became shorter, but the duration of heat generation became shorter. However, changes in the properties of the heat generating material were sufficiently detectable, and by increasing the amount of air supplied, the time for measuring the properties could be reduced by about 20% while detecting differences in the reactivity of the heat generating material.

[Effects of the Invention] By using the heat generating material characteristic evaluation device of the present invention, there are few disturbances, differences in the characteristics of the heat generating materials can be measured with high precision, and the number of measurement materials can be reduced due to less variation. Also, by increasing the air supply,
It is an effective evaluation method that allows the evaluation of heat generation characteristics in a shorter time than the JIS method.

[Brief explanation of drawings]

Figure 1: Schematic diagram of heat generation characteristic measurement using JIS method Figure 2:
Configuration diagram of this exothermic characteristic measuring device Figure 3: Relationship between air supply amount and exothermic characteristics Figure 4: Relationship between container insulation and exothermic characteristics Figure 5 2 Relationship between presence or absence of nitrogen substitution and exothermic characteristics Figure 6: Relationship between temperature sensor Relationship between insertion position and heat generation characteristics Figure 7: Characteristic measurement time of materials with different reactivity Figure 8:
Example of measurement by changing the amount of air supplied to materials with different reactivity.

Claims (1)

[Claims] 1. After compounding a disposable body warmer heat-generating material based on the oxidation reaction of iron powder in a container purged with nitrogen, it is filled into an insulated reaction container configured to adjust the amount of air supplied, and the temperature is directly applied to the material. A method for evaluating the heat generation characteristics of disposable hand warmer materials, characterized by inserting a measurement sensor.