JPS6227762B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for fixing seed beds with good water resistance. More specifically, the present invention relates to a seed bed fixing method with good water resistance, which is characterized by spraying a blended composition containing a polyvinyl alcohol resin, a water-insoluble polyisocyanate, water, and seeds as essential components onto the soil surface.

Many methods have been proposed for stably fixing seeds on artificially formed soil surfaces, and many chemicals are known for use in each method, but each method has its advantages and disadvantages. However, in reality, it is currently only used under very limited conditions. In view of the current situation, the present inventors have made earnest efforts to improve the shortcomings of conventionally known seed bed anchoring methods, and as a result, have completed a seed bed anchoring method that is excellent in safety, workability, and economy.

Conventionally known seed bed fixatives (abbreviated as fixatives below)
Examples include acrylamide-based, polyamine-based, water-soluble urethane-based, water glass-based, and cement-based fixing agents, but these fixing agents have the following problems.

(b) Water-soluble components are strongly acidic, strongly alkaline, or highly toxic, so there are concerns about the safety of water systems.

(b) The gelation or solidification time after blending or mixing is too fast, which limits the freedom of construction work.

C. Physical properties such as elasticity, strength, water resistance, and water content of the solidified material cannot be broadly controlled.

D. Adhesion to soil particles is low.

In addition, synthetic resin emulsions, rubber latex, bituminous emulsions, etc. are known as fixing agents for the seed bed fixing method, but all of these have poor water resistance, especially against rainfall immediately after construction. do not have.

On the other hand, when using a water-soluble urethane prepolymer, which has been used in some areas recently, a highly water-resistant and elastic foam is formed, and it is an excellent drug in terms of performance, but it has poor field workability and price. However, it has its drawbacks, and in reality, it is only being used on a trial basis in a very limited number of areas. In other words, water-soluble urethane prepolymers gel by reacting with water, and the time from mixing with water to gelation is
That is, since the gelation time is extremely short, ranging from several minutes to several tens of minutes, it is practically impossible to mix and spray in a tank. Therefore, it is necessary to use a special device that proportionally mixes the water-soluble urethane prepolymer and water near the nozzle tip.Furthermore, the resin raw material itself easily absorbs moisture and becomes thick and gelled due to moisture absorption, so the viscosity It has problems such as poor stability and the fact that proportional mixing is extremely difficult in practical terms.Although it has excellent performance, it is not easy to work on site, so it is not widely put into practical use. It is.

The present invention provides a new seed bed fixing method that improves the drawbacks of these known seed bed fixing methods, and uses a blended composition that is well-balanced in terms of performance, on-site workability, and price. It is applicable to a wide range of seed bed fixing methods and has great significance. That is, the gelling composition used in the method of the present invention, which has water-soluble polyvinyl alcohol resin, water-insoluble polyisocyanate, water, and seeds as essential components, can be prepared by changing the blending composition, catalyst, and mixing conditions. By this, it is possible to control the gelation time in the range of several tens of minutes to several hours, and furthermore, the physical properties such as the strength and elastic modulus of the gelled product can be changed over a wide range.

Furthermore, even though it is a two-component mixture type, it has a long pot life after blending and can control gelation time, making it easy to work on site. Another advantage of the seed bed fixing method of the present invention is that it does not contain.

As the polyvinyl alcohol resin used in the present invention, any water-soluble resin that is a saponified product of a polymer whose main component is vinyl acetate can be used, but in particular, polyvinyl alcohol resins with a degree of polymerization of 300 or more,
So-called partially saponified polyvinyl alcohol resins having a degree of saponification of 95 mol% or less are preferred in terms of liquid stability, gelling properties, solubility, and the like. carboxyl group, sulfone group, salts thereof, amide group,
So-called modified polyvinyl alcohol resins containing one or more types of long-chain alkyl ester groups, etc., and so-called so-called modified polyvinyl alcohol resins that are obtained by reacting aldehydes, acid anhydrides, vinyl monomers, etc. with the OH groups of polyvinyl alcohol resins. Post-modified polyvinyl alcohol resins and the like can also be suitably used. These modified polyvinyl alcohol resins have characteristic performance in terms of room temperature solubility, solution stability, emulsion stability of non-aqueous polyisocyanates, and the like. When the degree of polymerization of the polyvinyl alcohol resin is lower than 300, the gelation efficiency decreases and a large amount of polyisocyanate is required, which is not economical and generally not preferred. In addition, the degree of saponification of polyvinyl alcohol resins varies depending on the degree of modification, but in general, when the degree of saponification exceeds 95 mol%, it becomes difficult to emulsify and the solubility in water at room temperature decreases. This is not preferable because it impairs on-site workability.

Furthermore, the polyvinyl alcohol resin in the present invention refers not only to those used alone, but also to polyvinyl alcohol resins that are contained in various aqueous emulsions as emulsifiers, stabilizers, thickeners, or additives. It is included as one aspect of.

These aqueous emulsions containing polyvinyl alcohol resins include vinyl acetate, ethylene vinyl acetate, acrylic, styrene butadiene, styrene isoprene, styrene acrylic, vinyl chloride, vinylidene chloride, chloroprene, and bitumen. Any aqueous emulsion such as rubber emulsion or natural rubber emulsion can be used. Furthermore, -OH groups, -COOH groups, -NH ₂ are present in the emulsion resin components.
More preferably, the emulsion is an aqueous emulsion containing a functional group having an active hydrogen that can react with an isocyanate such as a group.

As water-insoluble polyisocyanates, aromatic diisocyanates such as m- and p-phenylene diisocyanate, 4-t-butyl-m-phenylene diisocyanate, 4-methoxy-m-
Phenyl diisocyanate, 4-phenyxy-
m-phenylene diisocyanate, 4-chloro-
m-phenylene diisocyanate, 2,4- and 2,6-toluene diisocyanate, m- and p-xylene diisocyanate, cumene-2.
4-diisocyanate, duyulene diisocyanate, 1,4-, 1,8- and 2,6-naphthyne diisocyanate, 1,5-tetrahydronaphthylene diisocyanate, diphenylmethane-4.
4'-diisocyanate, dianisidine diisocyanate, polymethylene polyphenyl isocyanates, toluene-2,4,6-triisocyanate, diphenyl-2,4,4'-triisocyanate, triphenylmethane-4,4',4'' - Many isocyanate compounds, such as triisocyanates and aliphatic diisocyanates, such as hexamethylene diisocyanate, decamethylene diisocyanate, 2,3-dimethyltetramethylene diisocyanate, as well as cycloaliphatic polyisocyanates, such as hydrogenated methylene diisocyanate, isophorone diisocyanate, etc. However, liquid crude diphenylmethane diisocyanate and polymethylene polyphenyl isocyanate are preferably used from the viewpoint of safety, stability, and economy.

Catalysts that promote or suppress the reaction of isocyanate, such as organic tin compounds, basic compounds, and acidic compounds, may also be added as appropriate. Generally, organic tin compounds such as dibutyltin dilaurate, tin octylate, triethylamine, triethylenediamine,
Basic compounds such as lime, soda carbonate, caustic soda, and other alkaline substances are positive catalysts that promote the reaction of isocyanates, and acidic properties such as phosphoric acid, hexametaphosphoric acid, and sulfuric acid promote the reaction of isocyanates. It is a negative catalyst that suppresses When using crude diphenylmethane diisocyanate as the water-insoluble polyisocyanate, it is better to use hexametaphosphoric acid together to keep the PH of the composition on the acidic side.
The gelation time is long and there is more room for on-site work.
Generally convenient.

The concentration of the polyvinyl alcohol resin contained in the compounded composition used in the present invention should be appropriately selected depending on the purpose of use, the concentration of other additives, etc., but is usually in the range of 0.1 to 20% by weight. It is appropriate to choose from. If the concentration is too low, the gelation efficiency will decrease, and only local gels will be formed instead of forming a gel overall, and the gelation rate will also be extremely slow, making it necessary to add a large amount of water-insoluble polyisocyanate. This method does not meet the purpose of the present invention because it has many disadvantages such as the following.

In the present invention, the amount of water-insoluble polyisocyanate contained in the gelling composition also needs to be appropriately increased or decreased depending on the type of isocyanate, purpose of use, conditions of use, etc. 1 to 1000 relative to the amount of alcohol resin present
A range of weight % is suitable, preferably 10 to 100
It is safe to choose from a range of weight %.

Since the polyisocyanate in the compounded composition used in the present invention is insoluble in water, it is necessary to be in a finely dispersed state in the composition, but in general, when left standing for a long time, the density of the polyisocyanate increases. Due to the difference, it tends to sink or float, resulting in an uneven state.
In order to prevent such phase separation, the following measures are effective.

(1) Always stir the system.

(2) Improve the dispersion stability of water-insoluble polyisocyanate by using a polyvinyl alcohol resin with strong emulsifying power or by using a small amount of emulsifier.

(3) Increase the viscosity of the system and slow down the sedimentation or floating speed of dispersed particles.

Polyvinyl alcohol resins with strong emulsifying power have as low a degree of saponification as possible, with residual acetic acid groups arranged in a block pattern, or modified products obtained by copolymerizing a small amount of long-chain alkyl vinyl esters. Polyvinyl alcohol and the like are preferred.

An effective way to increase the viscosity of the system is to add a thickener and/or filler to the system. Examples of thickeners include methyl cellulose, carboxymethyl cellulose, methyl vinyl ether, polyacrylamide, polyethylene oxide, and starch. In addition, as fillers, clay, calcium carbonate, titanium oxide,
In addition to inorganic powders such as silicon oxide, zinc oxide, gypsum, and perlite, organic materials such as pulp, waste paper, resin powder, fiber waste, straw waste, grains, wood flour, dried sludge, livestock manure, and sponge waste can also be used. Available as required. In short, anything that can reduce the fluidity of the system can be used as appropriate. Furthermore, in the case of the seed bed fixation method, if the water resistance of the film formed on the soil surface is too high, it becomes extremely difficult for water to penetrate into the soil, which tends to inhibit plant growth. To prevent this, it is effective to incorporate porous water-retaining substances such as foam, straw waste, wood flour, cotton waste, grain, pulp, and water-absorbing resin into the composition.

In preparing the compounded composition used in the present invention, first, an aqueous solution containing a polyvinyl alcohol resin is prepared, and then the seeds are dispersed or diluted in water, if necessary, with a thickener and a filler. The recommended method is to mix the ingredients with fertilizer and other additives under stirring, and finally add the water-insoluble polyisocyanate and then thoroughly stir and knead, but the method is not limited to this method.

The gelation time of the compounded composition used in the present invention can be controlled within the range of 30 minutes to several hours after preparation, but the addition of acidic substances, especially phosphoric acids, can delay the gelation time. Effective and straightforward.
Furthermore, the gelation time can be delayed by selecting a highly hydrophobic polyisocyanate, or by dissolving the polyisocyanate in a highly hydrophobic organic solvent and then adding it to water. .

On the other hand, in order to accelerate the gelation time, it is effective to use catalysts such as organic tin compounds and amines, and to add basic substances. It is effective to use additives and stirring conditions that make the isocyanate particles more finely dispersed.

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but these Examples are not intended to limit the present invention in any way.

Example 1 A spray composition for a seed bed fixing method was prepared with the following blending ratio, and sprayed on a slope to fix seeds.

Blend composition table (seed bed fixation) Component Blend amount (per 1000) A Polyvinyl alcohol (polymerization degree 1700, saponification
88 mol%) 20Kg B Crude diphenylmethane diisocyanate (Millionate MR-100 manufactured by Nippon Polyurethane Co., Ltd.) 15Kg C Waste paper pulp 30Kg D Chemical fertilizer 20Kg E Seed Kentucky 31 8Kg White clover 5Kg F Organic soil 250Kg Approximately 10 days after spraying It germinated and grew smoothly. During this period, a total of 450 mm of rain fell, but no seeds were washed away and germinated from the entire surface of the sprayed surface.

As a control, the same spraying was carried out using a similar composition containing only vinyl acetate emulsion as a binder, which has been carried out in the past. It was seen everywhere.

Claims (1)

[Claims] 1. A seed bed fixing method with good water resistance, characterized by spraying a blended composition containing a polyvinyl alcohol resin, a water-insoluble polyisocyanate, water, and seeds as essential components onto the soil surface.