JPH0628678B2 - Disposable heat insulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a disposable heat retaining device.

[Conventional technology]

Cover the exothermic agent such as iron powder with a breathable covering material, store it in a non-breathable bag, and crush the non-breathable bag by rubbing and rubbing the non-breathable bag to oxidize the iron powder when used. It is well known that a heat-retaining device such as a disposable pocket furnace utilizing the heat of oxidation that is generated is widely used because it is safe without using a fire.

Thus, the heat generation amount per hour of the heat retaining device as described above is determined by the amount of the heat generating agent composed of iron powder, a catalyst and the like and the amount of oxygen supplied through the air permeable covering material that encloses the heat generating agent. If the material and amount of the exothermic agent are constant, it is uniquely determined by the amount of oxygen supplied, that is, it depends on the ventilation amount of the breathable covering material. .

Therefore, if the ventilation amount of the breathable covering material is too large, there is a problem that it becomes too hot during use and can be used only for a short period of time. Conversely, if the ventilation amount is too small, sufficient heat is not generated and as a heat retaining device. Causes the problem that it cannot play the role of.

Thus, although the air permeability of the breathable covering material is a very important factor that determines the function of the heat retaining device,
The choice was not always made properly.

Conventionally, as a breathable covering material, a material such as a nonwoven fabric laminated with a resin film provided with ventilation holes in advance,
Or, a material in which a resin film is laminated on a non-woven fabric and then a hole is formed with a needle or the like is used. However, in this case, the diameter of the vent hole is apt to be large, and therefore, when the ventilation amount is too large, the iron as a heat generating agent is also used. There is a problem that the fine powder leaks out from the ventilation hole.

In order to improve these problems, it has been proposed to use a film having air-permeable micropores, leaving a ventilation part that gives the desired heat generation characteristics and leaving other parts non-breathable. As a method of imparting non-breathability to other portions, a film having ventilation holes provided in advance is laminated with a film having breathable fine pores, or a resin-based substance is partially added to the film having breathable fine pores. A method of restricting the air permeability by applying it on the whole surface or on the whole surface is adopted. The air-permeable film having fine pores can be obtained by treating a resin film containing calcium carbonate with an acid or by stretching means, but the air hole has a pore size of 10 μm or more.
Since many particles having a size of more than 30 μm are also generated, unevenness of heat generation, that is, variation occurs. Further, if a film provided with a ventilation hole is laminated, the cost becomes high and the ventilation part becomes partial, so that the deviation of heat generation is inevitably left.

Further, in the method of applying a solution containing a polyurethane-based resin as a main component on the entire surface and drying and then applying the polyurethane-based resin on the entire surface, it is difficult to control the air flow rate, and in addition, it is necessary to remove the solvent and the cost increases. There was a problem.

[Problems to be solved by the invention]

The object of the present invention is to solve the above-mentioned problems, and the object is to secure an appropriate oxygen supply amount to the exothermic agent, and thereby to obtain an appropriate heat value per hour. The object of the present invention is to provide a warming tool that maintains the above-mentioned value, has a small variation, extends the number of hours of use, and has good wearability during use.

[Means for solving problems]

In order to achieve the above object, in the heat insulator according to the present invention, 100 parts by weight of a polyolefin resin and an electric conductivity of 250 μs / cm or less and a particle size of 0.1 to 7.0 are used as the breathable covering material. A resin composition comprising 50 to 500 parts by weight of barium sulfate having a diameter of μm is melt-cast at least 1.5 in at least one axial direction.
Adopt ultra-fine air-permeable film stretched ~ 7.0 times.

The polyolefin resin in the present invention includes, for example, low density polyethylene, high density polyethylene, linear low density polyethylene, homopolymers such as propylene and butylene, ethylene-propylene copolymer, ethylene-butylene copolymer, ethylene-vinyl acetate. It is a copolymer such as a copolymer or a composition comprising these.

The barium sulfate in the present invention has an electric conductivity of 25.
It is preferably 0 μs / cm or less, preferably 100 μs / cm or less. When the electric conductivity of barium sulfate exceeds 250 μs / cm, the screen life is shortened due to the agglomeration of barium sulfate, frequent stretching breaks occur, and production stability is impaired.

The electric conductivity is a value obtained by adding 10 g of barium sulfate to 100 m of pure water, heating at 100 ° C. for 10 minutes, and then cooling and measuring the swelling liquid.

If the electric conductivity is too large, it may be used by further lowering it to the electric conductivity specified in the present invention by further washing with water or neutralizing with an acid and then washing with water again.

The average particle size of barium sulfate used is 0.1 to 7.0.
It is suitable that the thickness is μm, preferably 0.5 to 5.0 μm. If the average particle size is less than 0.1 μm, good air permeability cannot be obtained, and conversely, if the average particle size is greater than 7.0 μm, the stretchability deteriorates and the pore size increases, which is unsuitable.

The particle size of barium sulfate was obtained by filling 3 g of a sample into a 2 cm ² × 1 cm sample cylinder with a powder specific surface area measuring instrument and measuring the air permeation time of 5 cc with a 50 mm water column.

The compounding amount of barium sulfate in the resin composition used in the present invention is 50 to 5 per 100 parts by weight of the polyolefin resin.
It is 00 parts by weight, preferably 100 to 200 parts by weight.

If the amount used is less than 50 parts by weight, good air permeability cannot be obtained.If it is used in excess of 500 parts by weight, the rigidity of the film increases and sufficient stretching cannot be performed, resulting in a decrease in air permeability. I will end up.

Surface treatment of barium sulfate with a fatty acid, silicon, silane, resin acid or the like is effective for further enhancing dispersibility in resin and enhancing stretchability.

Next, the ultra-microporous breathable film according to the present invention can be obtained, for example, by the following production method.

The above polyolefin resin and barium sulfate are mixed with other additives that are usually used as needed, and then mixed using a Henschel mixer, a super mixer, or a Tangler-type mixer, and then a normal single-screw or twin-screw extruder. Knead and pelletize. These pellets are then fed to an inflation molding machine or T
The film is formed using a die molding machine. At this time, it is also possible to directly form a film by an extruder without pelletizing.

Then, the film is stretched at least uniaxially by a ratio of 1.5 to 7.0 by a conventional method. Stretching may be performed in multiple stages,
It may be stretched in two or more directions. After stretching, heat setting may be performed to increase the morphological stability of the pores.

The air permeability is determined by the amount of barium sulfate used, the particle size, the draw ratio, etc., but if the draw ratio is less than 1.5 times, sufficient air permeability cannot be obtained, and if the draw ratio is greater than 7.0 times, stretch breakage occurs,
We cannot produce it stably.

The air permeability of the ultra-fine pore breathable film is 500 seconds / 100cc to obtain an appropriate amount of heat generation in the heat insulator used for pocket furnaces, etc.
The above is desirable, and more desirably 5,000-50,000 seconds / 100
It is cc. The air permeability is a value measured according to JIS-8117.

[Action]

With the above configuration, the amount of oxygen supplied to the exothermic agent is appropriately maintained and an appropriate amount of heat is obtained, and the number of usable hours is extended by 20 to 30% as compared with the conventional one, and the exothermic composition is deviated. There is no inconvenience. Furthermore, since the amount of ventilation is small, the inside of the coating is kept in a reduced pressure state, and the shape retention is good, and many other advantages are obtained.

〔Example〕

Hereinafter, details of the present invention will be specifically described with reference to the drawings.

1 and 2 are cross-sectional views showing different embodiments of the heat retaining device according to the present invention, in which 1 is a heat-generating agent and 2 is a breathable coating for containing the heat-generating agent 1. As a material, an ultra-fine pore breathable film, 3 is a rayon nonwoven fabric provided in close contact with the ultra-fine pore breathable film, 4 is a non-breathable bag, and 5 is a non-breathable covering material.

At the time of use, the non-breathable bag 4 which also serves as the packaging is torn, and the heating agent 1 contained in the ultra-fine pore breathable film 2 and the rayon nonwoven fabric 3 is lightly kneaded as needed, and then used as a pocket heater. In some cases, it should be stored under clothes.

The exothermic agent 1 is composed of, for example, iron powder, NaCl (catalyst), and H ₂ O that gives moist air, and oxygen and iron in the air invading through the ultrafine pore permeable film 2 and the rayon nonwoven fabric 3 at the time of use. The powder reacts and generates heat due to the heat of the oxidation reaction.

The rayon nonwoven fabric 3 is for ensuring the feel of the skin and proper heat insulation when used as a pocket warmer.

Examples-1 to 5 The ultra-fine pore breathable film is a low density polyethylene (LDP) having a melt index (MI) = 3 according to Table-1.
E) or linear low density polyethylene with MI = 2 (L-
LDPE) or polypropylene with MI = 1.5 (P
P) To 100 parts by weight, barium sulfate having an electric conductivity of 50 μs / cm and an average particle size of 0.8 μm was added in the amounts shown in Table 1 and mixed in a Henschel mixer, followed by uniform kneading with a twin-screw mixer. Then, pellets were prepared. After melt-forming the pellets at 230 ° C. by a T-die extruder, they are uniaxially stretched between a preheating roll heated to 50 ° C. and a stretching roll at a magnification shown in Table 1 to obtain a film having a thickness of 50 μm. It was The results of physical property evaluation of this film are shown in Table 1.

The physical properties of the film were evaluated by the following methods.

(1) Air permeability: In accordance with JIS-8117.

(2) Pore size: The maximum equivalent diameter of breathable micropores determined by the mercury porosimeter method.

By using the ultra-fine air-permeable film obtained from Table-1, keeping the supply of oxygen to the exothermic agent at an appropriate value, overheating does not occur, the use time is significantly longer than the conventional one,
It will be possible to extend the time to more than 24 hours, and it will be possible to maintain an appropriate usage temperature for the whole day.

Therefore, heat is not wastefully generated and dissipated, and the same heat retaining effect can be obtained with an amount of the exothermic agent which is about half that of the conventional one.

Furthermore, even if the oxygen in the air that has penetrated into the interior through the ultrafine pore permeable film 2 combines with the iron powder and the pressure inside the bag drops, only a small amount of air is replenished through the ultrafine pore permeable film. The inside of the bag is always kept in a decompressed state, so that the bag is in a tight state and the exothermic agent does not move inside the bag so that it is not biased, and good shape retention and fit are obtained. .

Comparative Example-1 Using a linear low-density polyethylene resin, a thickness of 50 obtained by melt-forming a linear low-density polyethylene in the same manner as in Example-1
As a result of evaluating the physical properties of the film (unstretched) having a thickness of μm, there was no air permeability as shown in Table 1.

Comparative Example-2 Electric conductivity of 5 with respect to 100 parts by weight of L-LDPE with MI = 2
After forming 600 parts by weight of barium sulfate having a particle size of 0 μs / cm and an average particle size of 0.8 μm in the same manner as in Example-1, uniaxial stretching was tried, but the film was hard and could not be stretched.

Comparative Example-3 Electric conductivity of 3 with respect to 100 parts by weight of L-LDPE having MI = 2
After forming 150 parts by weight of barium sulfate having an average particle size of 0.6 μm and 00 μs / cm in the same manner as in Example-1, the film was uniaxially stretched at the magnification shown in Table 1 to obtain a film having a thickness of 50 μm. However, if the film formation time becomes long, the screen will be clogged, and the resin pressure will become high, making production impossible. In addition, there is a problem that the film is opened due to the spots.

Comparative Examples 4 and 5 The fillers shown in Table 1 were formed into a film in the same manner as in Example 1 with respect to 100 parts by weight of L-LDPE having MI = 2, and uniaxially stretched at the magnification shown in Table-1. A film having a thickness of 50 μm was obtained.

As shown in Table 1, this film had a large pore size and a large amount of air permeation, so that it generated heat in a short time and had variations. In addition, the exothermic agent was biased, which caused discomfort when worn.

[Advantages of the Invention] Since the present invention is configured as described above, according to the present invention, the oxygen supply amount to the exothermic agent is appropriately maintained to obtain an appropriate heat generation amount, and the number of usable hours is also increased. It is longer than the conventional one, it is more than 24 hours, and the ventilation volume is small, so that the inside of the coating is kept in a reduced pressure state, and there are many advantages such as good shape retention and good fit, etc. It is a thing.

The constitution of the present invention is not limited to the above-mentioned embodiment, and for example, as the exothermic agent, exothermic agents other than those mentioned above can be used, and the rayon nonwoven fabric 3 is also made of other materials. Within the scope of its object, the invention embraces all modifications which can be easily conceived by a person skilled in the art from the above description.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a heat retaining tool according to the present invention, and FIG. 2 is a sectional view showing another embodiment of a heat retaining tool according to the present invention. 1 ... Exothermic agent 2 ... Ultra fine pore breathable film 3 ... Rayon non-woven fabric 4 ... Non-breathable bag 5 ... Non-breathable coating material

Claims (1)

[Claims] Claim: What is claimed is: 1. A disposable warming device comprising a heat-generating agent capable of generating heat in the presence of air, which is covered with a breathable covering material, and which is housed in a non-breathable bag. As 100 parts by weight of polyolefin resin, electrical conductivity of 250 μs / cm or less, and particle size of 0.1-
A disposable heat retention tool, characterized by using an ultrafine pore breathable film obtained by melt-casting a resin composition comprising 50 to 500 parts by weight of barium sulfate having a size of 7.0 μm and stretching the film at least uniaxially 1.5 to 7.0 times.