JPH069949A - Artificial snow and prevention of consolidation of artificial snow - Google Patents

Abstract

PURPOSE:To prevent an artificial snow made of water-swellable polymer particles frozen in a hydrated state from being consolidated under the influence of semibound water in the polymer gel. CONSTITUTION:The snow consists of water-swellable polymer particles frozen in a hydrated state and frozen water layers c adhering to the surfaces of the respective particles and being in a state not infiltrated into the polymer. The prevention method comprises supplying water to the surfaces of water-swellable polymer particles G frozen in a hydrated state at a temperature below the freezing point to form frozen water layers c on the surfaces of the respective particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to artificial snow made from water-swellable polymer particles frozen in a water-containing state, and a method for preventing its solidification.

[0002]

2. Description of the Related Art Conventionally, artificial snow of this type, that is, polymer particles that have been impregnated with water and gelated and then frozen (hereinafter referred to as frozen gel particles) are used as individual snow grains. In the artificial snow formed by the accumulation of particles, the frozen gel particles accumulated in a state where the frozen surfaces of the gel were in direct contact with each other to form a snow layer.

Further, in order to make the artificial snow layer light and soft so as to be suitable for skiing purposes, a method of finely cutting and crushing the snow layer by a cutting device is adopted.

[0004]

However, this artificial snow has a strong tendency to gradually solidify and become harder at the time of freezing, and the cutting and crushing treatment is frequently performed in order to maintain a state suitable for skis and the like. Had to be done.

Incidentally, according to the experiment, the density is 450 kg / c.
The hardness of m ³ is generally 720 in about 20 hours.
It has been observed to rise from kg / cm ² to 3000 kg / cm ² (Kinoshita hardness meter).

With regard to the cause of this solidification, the water absorbed by the water-swellable polymer is changed into bound water that binds to the polymer composition, unbound free water, and in the middle, a weak bound state to the polymer composition. It is known that there are three types of semi-bonded water in the gel, but free water has the same freezing point as normal water, whereas bound water does not have a freezing point and semi-bonded water is It has a lower freezing point than normal water.

Therefore, when this kind of artificial snow is generally maintained at several degrees below freezing and used for skiing, free water, which occupies about 98% of the absorbed water, is present in the gel in a frozen and solidified state. , And bound water is in a stable state constrained by a strong bond with the polymer composition, whereas semi-bound water exists in a relatively free liquid phase and is at the surface of frozen gel particles in direct contact with each other. It is considered that the presence of the liquid phase semi-bonded water promotes the sintering of the frozen gel particles as snow grains.

An object of the present invention is to suppress the influence of semi-bonded water in the gel between frozen gel particles to prevent the above solidification phenomenon.

[0009]

The artificial snow according to the present invention is characterized in that the surface of the particles of the water-swellable polymer frozen in a water-containing state has a frozen layer of water that is not impregnated with the polymer. Especially.

The characteristic constitution of the method for preventing artificial snow solidification according to the present invention is that artificial snow made of water-swellable polymer particles frozen in a water-containing state is used to apply water to the surface of the particles in a sub-zero state. To form a frozen layer of the applied water on the surface of the particles.

[0011]

In other words, in the above-mentioned artificial snow structure, the frozen layer of water that is not impregnated into the polymer, that is, the gel-forming water (bound water, semi-bonded water, free water) outside the gel and in the gel
The surface of the frozen gel particles is covered by a frozen layer of water that is totally frozen below freezing with water that is distinct from, and therefore even if semi-bonded water in the liquid phase is present in the frozen gel particles below freezing. , The liquid phase semi-bound water is confined in the freezing layer on the gel surface, and contact with other frozen gel particles is blocked.

In the solidification preventing method, the surface of the particles of the water-swellable polymer frozen in the water-containing state (that is,
By applying water below the freezing point to the surface of the frozen gel particles), the applied water is frozen on the surface of the frozen gel particles,
As a result, a frozen layer of water that is not impregnated with the polymer, that is, an frozen layer that traps liquid phase semi-bonded water in the frozen gel particles, is formed on the surface of the frozen gel particles.

[0013]

As described above, as a result of the operation, according to the artificial snow and the method for preventing solidification of the present invention, it is possible to suppress the sintering of the frozen gel particles due to the influence of the liquid phase semi-bonded water. It is possible to effectively prevent the solidification and hardness increase of the snow layer, which makes it possible to maintain the snow condition suitable for the purpose of skiing etc. for a long time, and reduce the frequency of cutting and grinding treatment compared to before. Came to.

According to the experiment, the density is 450 kg / c.
hardness of 720 kg / cm ² to 30 for m ³
Conventionally, the solidification time for increasing the pressure to 00 kg / cm ² was about 20 hours as described above, but by applying the present invention, the solidification time could be extended to about 72 hours.

[0015]

EXAMPLES Next, examples will be described.

FIG. 1 shows the equipment structure of an indoor artificial snow ski resort, 1 is a building, 2 is a sloping floor provided with heat insulating means 2a, 3 is a cooling pipe laid over substantially the entire surface of the sloping floor 2, 4
Is a low-temperature refrigerator that cools a refrigerant (for example, brine) that circulates in the cooling pipe 3.

Numeral 5 is an air-conditioning facility for controlling the temperature and humidity inside the room, which is provided with a dehumidifying means 5a, a temperature adjusting means 5b, and a humidifying means 5c, and which has return air Ar from inside and outside air A from outside.
The temperature and humidity of the air mixed with o is adjusted by the air conditioning equipment 5, and this temperature and humidity adjusted air As is sent indoors by the fan 6.

Reference numeral 7 is a detector for detecting the indoor temperature tr and relative humidity r, 8 is a detector for detecting the cooling temperature tp of the cooling pipe 3, and 9 is based on the detection information of these detectors 7, 8. It is a control device that controls the operation of the low temperature refrigerator 4 and the air conditioning equipment 5.

Regarding the formation of the snow layer, first, prior to the formation of the snow layer, the sand layer 10 in which the cooling pipe 3 is embedded is placed on the inclined floor 2.
The sand layer 10 is impregnated with water by sprinkling water, and the water-containing sand layer 10 is frozen by being cooled by the cooling pipe 3.

Then, the water-swellable polymer (granular or amorphous material of about 1 to 2 mm) and water are mixed in a separate container at a predetermined mixing ratio, and the mixture of this polymer and water is pumped onto the frozen sand layer 10. Sprinkle on.

The spraying is carried out before the polymer is completely gelated by water absorption, that is, the polymer is in the middle of water absorption, whereby the completely gelled polymer is pumped. The required pump power is reduced compared to

The mixture of polymer and water has a thickness of 100 to 15
It is sprayed so as to form a layer 11 of about 0 mm, but the sloping floor 2
In order to prevent the above-mentioned mixed flow from falling, a temporary weir 12 as shown by the broken line in the figure is provided in advance at an appropriate interval on almost the entire surface of the inclined floor 2.

The gelation of the polymer due to water absorption proceeds on the inclined bed 2, and finally the mixed layer 11 of polymer and water is frozen in the gel state by cooling by the cooling pipe 3 to form a frozen gel layer.

The frozen gel undergoes self-destruction due to the expansive force of absorbed water that accompanies freezing and overcomes the gel strength. Due to this self-destruction, the frozen gel is in a state in which a large number of fine cracks are formed and is easy to pulverize.

After forming the frozen gel layer 11, the temporary weir 12 is formed.
Of the frozen gel layer 11 (thickness 15
mm) is crushed and cut by a cutting device.
The artificial snow layer 11a is formed by stacking fine frozen gel particles (particle diameter of about 0.1 to 0.3 mm).

The artificial snow layer 11a has a larger volume (for example, a thickness of 30 mm) than before the cutting process by containing a large amount of air at the time of cutting and crushing, and becomes a light and soft snow layer similar to natural snow.

After the cutting treatment, an appropriate amount of water is sprinkled on the artificial snow layer 11a to add water to the surface of the frozen gel particles forming the snow layer 11a, and the added water is cooled by the cooling pipe 3 in the snow layer. As shown schematically in FIG. 2, the frozen water is frozen on the surface of each frozen gel particle G (that is, the particle surface of the polymer frozen in the water-containing state) to freeze the water that is not impregnated with the polymer. A layer, that is, an ice layer c of water outside the gel and distinguished from the gel-constituting water (bound water, semi-bound water, free water) in the gel is formed.

That is, even if liquid phase semi-bonded water having a low freezing point is present in the frozen gel particles G, the liquid phase semi-bonded water is kept in the above-mentioned freezing layer c so that the liquid phase The binding water is prevented from promoting the sintering of the frozen gel particles G to each other, whereby the solidification and the hardness increase of the snow layer due to the sintering are suppressed, and the snow condition suitable for the ski purpose is maintained for a long time. To do so.

If the frozen gel particles G are bound to each other due to the freezing of the applied water, the cutting process is performed again by a cutting device as necessary, whereby the frozen gel particles G due to the freezing of the applied water. The bond between them is destroyed and the snow quality is restored to the same level as after the initial cutting process.

Further, in this re-cutting process, some frozen gel particles G which are divided by the portion other than the frozen layer c of the imparted moisture are also generated, but stochastically, the imparted moisture frozen layer c exists on the particle surface. Due to this, the frozen gel particles G in which the semi-bonded water is confined also remain in the snow layer 11a with a high probability, whereby the desired solidification prevention is sufficiently achieved.

On the other hand, when used as a ski resort, the controller 9 controls the air conditioner 5 based on the deviation Δtr between the indoor temperature tr detected by the detector 7 and the set value trr so that the indoor temperature tr becomes the set value trr. Temperature control means 5b in
Adjust the temperature control output of.

As the set value trr of the indoor temperature tr, a low temperature value suitable for suppressing melting of the snow layer 11a is adopted within a range that does not cause thermal shock or discomfort to indoor persons.

In parallel with the indoor temperature adjustment, the controller 9 controls the indoor temperature tr detected by the detector 7 and the snow layer surface temperature t.
Based on the set value tss of s, the surface temperature ts of the snow layer 11a is set by calculation in consideration of the heat conductivity between the cooling pipe 3 and the snow layer surface and the heat transfer coefficient between the snow layer surface and the air. The cooling temperature tpp of the cooling pipe 3 that gives the value tss is calculated, and the calculated cooling temperature tpp is set as the target cooling temperature,
The cooling output of the low-temperature refrigerator 4 is adjusted based on the deviation Δtp between the cooling temperature tp detected by the detector 8 and the calculated cooling temperature tpp so that the cooling temperature tp of the cooling pipe 3 becomes the target cooling temperature tpp.

The set value tss of the snow layer surface temperature ts can be changed by setting the setting means 9a. Generally, the lower the snow layer surface temperature ts, the higher the dynamic friction coefficient of the snow layer surface. On the other hand, by changing the set value tss of the snow layer surface temperature ts in the above-mentioned cooling temperature adjustment, the skiing property of the ski can be adjusted.

Further, the control device 9 controls the indoor air A based on the indoor temperature tr and the relative humidity r detected by the detector 7.
The dew point temperature td of r is calculated, and based on this calculation result,
The dew point temperature td of the indoor air Ar is higher than the set value tss of the snow layer surface temperature ts by a predetermined temperature Δt (for example, Δt = 1 ° C. de
The dehumidifying means 5a and the humidifying means 5c in the air conditioning equipment 5 are controlled so that the value is adjusted and maintained at a value g) higher.

That is, the set value tss of the snow layer surface temperature ts
A value higher than the above-mentioned predetermined temperature Δt by a target dew point temperature t
dd (= tss + Δt), and in a situation where the dew point temperature td of the indoor air Ar is less than the target dew point temperature tdd when the humidity is not adjusted, the dew point temperature td of the indoor air Ar is set to the target dew point temperature by the indoor humidification by the humidifying means 5c. Increase to tdd, the dew point temperature td of the indoor air Ar is the snow layer surface temperature t
By making the temperature higher than s (= tss) by a predetermined temperature Δt, the sublimation of water from the snow layer 11a into the air is prevented, thereby maintaining the above-mentioned added water freezing layer c, Prevents deterioration of snow quality due to sublimation of water, and deterioration of gliding properties accompanying it.

In addition, indoor air Ar without humidity adjustment
In the situation where the dew point temperature td of A becomes higher than the target dew point temperature tdd, the indoor air A is dehumidified by the dehumidifying means 5a.
The dew point temperature td of r is lowered to the target dew point temperature tdd so that the dew point temperature td of the indoor air Ar becomes equal to the snow layer surface temperature ts.
By making the temperature higher than (= tss) by a predetermined temperature Δt, excessive moisture condensation and frost formation from the air onto the snow layer 11a are prevented, and as a result, such excessive moisture condensation occurs. -Prevent deterioration of snow quality due to frost formation, and deterioration of gliding properties.

[Other Embodiment] Another embodiment will be described below.

In order to form a frozen layer c of water not impregnated in the polymer on the particle surface of the water-swellable polymer frozen in the water-containing state (the surface of the frozen gel particle G), snow is used in the above-mentioned embodiment. Moisture was applied to the surface of the particles by spraying water on the layer 11a, but instead of this, by humidifying the air Ar on the snow layer, adjusting the cooling temperature of the cooling pipe 3 to adjust the snow layer surface temperature ts, etc. The dew point temperature td of the air Ar is compared with the snow layer surface temperature ts.
The temperature is higher than that of the frozen gel particles G, and thereby water in the air is frosted on the surface of the frozen gel particles G to form a frozen layer c of water that is not impregnated in the polymer on the surface of the frozen gel particles G. You may.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

[Fig.1] Facility structure diagram of indoor artificial snow ski resort

[Fig. 2] Schematic diagram of snow grains

[Explanation of symbols]

 G particle c Ice layer

Claims (2)

[Claims] 1. An artificial snow made of water-swellable polymer particles (G) frozen in a water-containing state as a raw material, wherein the surface of the particles (G) is not impregnated with the polymer. Artificial snow having an ice layer (c). 2. In artificial snow made of water-swellable polymer particles (G) frozen in a water-containing state as a raw material, water is applied to the surface of the particles (G) at a temperature below freezing to freeze the applied water. A method for preventing solidification of artificial snow, which comprises forming a layer (c) on the surface of the particles (G).