JPH07110937B2 - Manufacturing method of artificial snow - Google Patents

Description

BACKGROUND OF THE INVENTION (1) Field of the Invention The present invention relates to a method for producing artificial snow from crosslinked polymers. The artificial snow is then maintained and used as a suitable surface for skiing.

(2) Prior Art Addition of cross-linked polymers to water and the resulting gels have been used to form surfaces suitable for snow skiing and ice skating. Busseli (International Publication No. WO86 / 02936)
Is used to absorb up to 70% of its maximum capacity by aerating the water-swellable cross-linked polymer to form voids, and the individual gel particles are then frozen to form the ski surface. Describe the method. Walker (US Pat. No. 3,251,194) describes a method in which a crosslinked polymer is used to absorb to its maximum capacity and then laid on a subzero surface to form a solid sheet of ice suitable for ice skating. To do. The explicit intent of the present invention is to
Grinding the particles, thereby eliminating the need to aerate the mixture as in the Busselli patent or to make undesired solid ice sheets as in the Walker patent.

SUMMARY OF THE INVENTION The object of the present invention is to produce a frozen surface suitable for skiing, the surface of which may be indoors or outdoors. It is preferably kept ski-friendly by the use of sub-zero ambient surface temperature or an underlying refrigeration grate.

Frozen surfaces are coated with water-swellable, water-insoluble substances such as polymers and copolymers of acrylamide, acrylic acid, polyacrylates, vinyl oxazolidinones, methacrylates, vinyl ethers and styrene sulfonates,
It is produced by combining cellulose fibers with polymerized polymers and copolymers. The polymeric material is preferably mixed with water in a ratio such that maximum absorption is reached and preferably no free water remains. The maximum absorption depends on the polymer type and on the exact chemical composition of the water used. Water of preferably drinkable grade and having a total dissolved solids content of 600 ppm or less is preferably used. It is preferable to select a polymer having a water absorption rate in the range of 60 to 120: 1 by weight. Compounds of various chemical types have been added to swollen gels to inhibit bacterial and fungal growth, such compounds including carbamates, thiones and cyanobutanes. (These are the products commonly used to prevent growth in shampoos, detergents and a wide range of cosmetics.) The resulting gel is then preferably laid on a zero-ground surface or frozen grid. It is a preferred object of the invention to produce a final ski surface with various physical properties in which the individual particles of the frozen gel are remote and are not attached to all other particles in their vicinity. is there. This is achieved by a particular choice of gel strength, ie gel crosslink density and particle size. When frozen, the internal force associated with the expansion of water below 0 ° C overcomes the strength of the gel. This will cause the gel to break up into fine particles. The resulting product is a frozen surface consisting of a large number of small individual particles of frozen particles. Each particle is separate from the other particles. During the freezing and crushing process, the resulting gel particles of small size are separated from the particles in direct contact therewith. This results in a volume increase due to the inclusion of a large empty air filled space. The resulting surface resembles the surface appearance and physical properties of a unique snowflake.

This surface is preferably physically treated to ensure that all frozen gel particles are of relatively small size, consistent with natural snow crystals.

Various physical properties of the frozen surface can be altered by changing the crosslink density or particle size. Each time one of these variables is changed, the gel strength, and thus the amount of crushed material produced, or apparent volume, changes. Hard, densely packed snow can be produced by using particles with high crosslink density, and small particles and soft powdery snow can be produced by using polymers with low crosslink density and very large particle size .

BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of the present invention, preferred embodiments are described with reference to the accompanying drawings, which illustrate a schematic layout of the equipment used to manufacture ski slopes.

Description of the Preferred Embodiments of the Method The water-swellable polymer, which is mixed with water and frozen to produce individual ice crystals, can be produced, for example, from the following components.

(A) Water 100ml (b) Acrylate monomer 30ml (c) Tetramethylethylenediamine 1ml (d) 4% ammonium persulfate 4ml (e) Methylenebisacrylamide 200-2000ppm (Acrylate monomer basis) For soft snow, the mixture should be ( It may contain b) 30 ml of acrylate monomer and (e) 400 ppm of bisacrylamide. For hard snow, the (b) acrylate monomer can be replaced with a mixture of (b) 25 ml of acrylate monomer / 5 ml of acrylamide monomer, and the concentration of (e) bisacrylamide is increased to 1800 ppm.

The components are well mixed and allowed to react exothermically to produce a crosslinked polymer matrix capable of retaining 50-100 times its own weight of water on a solids basis in water.

The manufacture of ski surfaces using this crosslinked polymer will now be described.

The slope 10 is formed either on the side of the hill or within the indoor structure. The slope is bounded by sidewalls 11 that control the outflow of gel and avoid damage to the surrounding environment. A pipe 12 having a manifold 13 connected to a refrigeration unit 14 is provided. Brine, glycol or refrigerant pipe
Pumped through 12, then passed through heat exchanger 15 and returned via pump 16. The heat from the cryogen is dissipated by the liquid circulated by the pump 18 through the heat exchanger 15 and the cooling tower 17.

Water 20 is fed to a large tank 21, to which 60 to 120
The crosslinked polymer is added in a weight ratio of 1: 1. The crosslinked polymer is allowed to absorb all of the water in tank 21. The gel can be used only after no free water remains. If any free water remains, undesired particle bridging will occur during freezing to form an icy surface that is not suitable for snow skiing.

The resulting gel is pumped through line 24 onto the cryogen grid 10 by an aggressive transfer pump 23, such as a rotary or piston pump. A total thickness of gel 25 of about 100-200 mm is used. It can be laid as several layers of about 10-20 mm. The gel freezes and is allowed to undergo volume increase due to grinding and swelling. The surface 26 is then physically scraped, and the gel particles are encouraged to be further ground by mechanical grinding such as running on the surface with a tractor equipped with a rotary cutter or a scraper 27. Surface 26 is kept below -2 ° C by cryogen pipe 12. The slope 10 can be regularly scraped, or more gel can be added as a patch and allowed to freeze.

As mentioned previously, the physical properties of frozen surfaces are:
For example, it can be modified to emulate hard snow or light powder snow. It will be apparent to those skilled in the art that various changes and modifications can be made to the described embodiments without departing from the scope of the invention as defined by the claims.

Claims (12)

[Claims] 1. A step of: (a) contacting water with a water-swellable, water-insoluble polymeric material to form an aqueous gel at substantially the maximum water absorption of the polymeric material; and (b) water in the gel. The method for producing artificial snow, comprising the step of freezing the aqueous gel free of free water so that the internal force associated with the expansion of the gel overcomes the strength of the gel and breaks the gel into smaller individual particles. 2. The method of claim 1 including the step of (c) further grinding the gel particles by mechanical work to form a surface imitating natural snow. 3. The first and second gel particles are separated and are not attached to all other gel particles in the vicinity thereof.
The method of paragraph or paragraph 2. 4. The method according to claim 2, wherein the mechanical working of the gel particles is carried out by mechanical grinding and / or compaction of the gel particles. 5. A polymer material comprising a polymer or copolymer of acrylamide, acrylic acid, polyacrylate, vinyl oxazolidinone, methacrylate, styrene, vinyl ether, and styrene sulfonate. Either method of paragraph. 6. The method of claim 5 wherein the polymers and copolymers are polymerized with cellulosic fibers. 7. The polymeric material has about 60-12 its own weight in water.
The method of paragraphs 5 or 6 which absorbs 0 times more water and the water has no more than 600 ppm total dissolved solids. 8. The method of claim 5 wherein the aqueous gel for soft snow contains 200-1000 ppm of methylenebisacrylamide and 1000-2000 ppm of methylenebisacrylamide for hard snow. 9. The method of claim 8 wherein for hard snow the acrylamide monomer is mixed with acrylate monomer contained in an aqueous gel for soft snow. 10. The aqueous gel is pumped onto a frozen bed or grate as a layer about 10 to 20 mm thick to a total thickness of 100 to 200 mm, each layer being pumped before the next layer is pumped onto the bed or grate. The method of any of paragraphs 1-9, which is frozen and the gel particles are ground. 11. Artificial snow produced by the method according to any one of claims 1 to 10. 12. A ski slope comprising a frozen floor or grate and one or more layers of artificial snow produced by the method of any of claims 1 to 10 over the floor or grate.