JPH0149314B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention can be applied to slopes of developed land, collapsed mountains, etc. to improve the strength of the ground, to prevent soil from collapsing, to prevent scattering by wind, to prevent erosion by rain, or to flat areas such as grounds, construction roads, etc. This relates to chemicals for fixing soil, preventing soil scattering, erosion, etc. Spraying chemicals to prevent landslides has been carried out for a long time, and many organic chemicals such as asphalt emulsions and vinyl acetate resins have been proposed as spraying chemicals, but in general, the adhesion strength of the ground and soil is insufficient. In addition, it has insufficient permeability into the soil, has poor water resistance and freeze stability, and is therefore easily affected by weather, making it difficult to maintain soil stability over long periods of time. It was hot. The present invention eliminates the above-mentioned drawbacks, has excellent soil permeability and soil consolidation ability, and can form soil that is stable for a long period of time even in the face of severe weather changes. The objective is to develop a drug that can exhibit sufficient efficacy for seed germination and plant growth. Inside,
It consists of an acrylic polymer dispersion obtained by emulsion polymerization in the presence of an anionic emulsifier, and the pH of the dispersion is 5 to 9, and the glass transition temperature (hereinafter referred to as Tg point) of the polymer is -40℃ to +20℃. It is a soil erosion prevention agent in the range of ℃. The main points of the present invention are that the emulsifier and PH are limited to stabilize the drug in order to increase its permeability into the soil, and that the soil solidification ability is maintained over a long period of time. The aim is to use acrylic polymers having a Tg point within a certain range, and these will be specifically explained below. The acrylic polymer constituting the drug of the present invention is a polymer obtained by emulsion polymerization of monomers mainly composed of acrylic esters and/or methacrylic esters, in which the above ester component is 50% (weight %; (The same applies hereinafter) or more, and the above monomers are substantially freely selected and blended so that the Tg point of the polymer falls within the range of -40°C to +20°C. In the present invention, when acrylic ester and methacrylic ester are used together, the blending ratio of both is determined by the hardness of the resin such that the weight ratio of acrylic ester and methacrylic ester is in the range of 85:15 to 30:70. It is preferable in terms of quality. As monomers that can be used in these acrylic esters and methacrylic esters, those in which the number of carbon atoms in the alkyl group is in the range of C ₁ to _{C 8} are preferable in terms of performance and cost. For example, methyl acrylate (Tg point of the homopolymer (hereinafter simply referred to as Tg point) +8°C), ethyl acrylate (Tg point -23
℃), acrylic acid esters such as butyl acrylate (Tg point -57℃), isobutyl acrylate (Tg point -24℃), 2-ethylhexyl acrylate (Tg point -85℃), methyl methacrylate (Tg point +105℃),
Examples include methacrylic acid esters such as ethyl methacrylate (Tg point +65°C) and butyl methacrylate (Tg point +20°C). In addition to the above-mentioned acrylic esters and methacrylic esters, one or more of the polymerizable monomers listed in ○A and ○B below can be blended. ○B Carboxyl group-containing polymerizable monomers such as acrylic acid and methacrylic acid, or hydroxyl group-containing polymerizable monomers such as hydroxyethyl acrylate, hydroxybutyl acrylate, and hydroxyethyl methacrylate, mainly for the purpose of imparting soil consolidation power. The preferred usage amount is 10 in the polymer.
% or less, and if the polymer contains more than this, water resistance deteriorates and the soil tends to collapse due to rainfall, which is not preferable. ○B Ethylene monomers, such as vinyl acetate, styrene, acrylonitrile, and vinylidene chloride, which are available at relatively low prices, mainly for the purpose of imparting hardness to resins and consolidation power to earth and sand. The suitable amount to use is that the Tg point of the polymer is -40 to +20℃,
Moreover, it is desirable that the content is 50% or less in the polymer. In addition, the hardness of the resin can be adjusted by adding known chain transfer agents, plasticizers, etc. during polymerization, if necessary. The Tg point is the temperature at which various properties of an amorphous polymer suddenly change, and below this temperature, the motion of the molecular segments of the amorphous portion of the polymer is frozen. To actually measure the Tg point of the polymer constituting the drug of the present invention, for example, the thermal expansion at various temperatures is measured and the Tg point is determined as the intersection of two straight lines with different slopes on the specific volume-temperature curve. It will be done. However, for convenience, the Tg of each single polymer is
Since the value of Tg at the point is known, the Tg point of the copolymer can be determined using the following calculation formula. 1/Tg=C _A /Tg _A +C _B /Tg _B ...(1) C _A : Weight fraction of component A C _B : Weight fraction of component B Tg _A : Glass transition temperature of component A single polymer (〓) Tg _B : Glass transition temperature of component B single polymer (〓) Tg: Glass transition temperature of component A, B copolymer polymer (〓) Here, C _A +C _B =1. The range of Tg points in the present invention from -40°C to +20°C is based on calculations from the Tg points of the individual polymers mentioned above. The drug of the present invention is obtained by performing radical emulsion polymerization of the above monomer in an aqueous medium using an anionic emulsifier using a conventionally known method, and then adjusting the pH of the liquid to 5 to 9.
You can reach your goal by adjusting. At this time, the emulsifier is specifically limited to an anionic emulsifier, and the purpose of adjusting the pH of the liquid to 5 to 9 is to stabilize the chemical sufficiently in order to spray it on the soil and allow it to penetrate deeply into the soil. This is because it is necessary to On the other hand, when the emulsifier is a cationic emulsifier or a nonionic emulsifier, the emulsion is destroyed in the soil surface layer, and the emulsifier cannot penetrate deeply into the soil. Further, even when emulsion polymerization is carried out using an anionic emulsifier as an emulsifier, if the pH of the liquid is 5 or less, the stability of the emulsion is poor, and therefore, in this case as well, it is difficult to penetrate deeply into the soil. In addition, if the pH is 9 or higher, if ammonia or amine compounds are used as pH adjusters, a bad odor will be emitted during spraying, resulting in environmental pollution.If other pH adjusters such as caustic soda are used, water resistance will decrease. Undesirable. Examples of anionic emulsifiers that can be used in the present invention include, but are not limited to, sodium lauryl sulfate, sodium polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether sodium sulfate, and polyoxyethylene alkyl ether sodium sulfate. Sodium sulfate type emulsifiers, such as ethylene alkyl phenyl ether sodium sulfate, are preferred. Acrylic polymer in the drug of the present invention
As mentioned above, the Tg point is in the range of -40℃ to +20℃, but when a chemical is sprayed on soil, it is necessary to solidify the soil after it penetrates into the soil, and the Tg point of the polymer is Although it has sufficient soil consolidation ability even in winter or in cold regions when the temperature is -40℃ or lower, its consolidation power is weak, making it impractical. Furthermore, if the Tg point is +20°C or higher, the resin becomes too hard, resulting in poor consolidation ability and the formation of cracks in the soil. In addition, the permeability into soil is naturally influenced by the concentration of the polymer, the viscosity of the emulsion, the size of the polymer particles, etc. According to the drug of the present invention, the concentration of the polymer is preferably 50% or less, and 5 to 30% by weight.
Particularly preferred are polymers dispersed in water. Those with a high concentration of polymer tend to have low permeability to soil, and those with low polymer concentration have good permeability but tend to have low consolidation power. There is no particular limit to the viscosity of the drug of the present invention, but it is preferably several cps to several + cps in order to enable penetration into dense soil. size can be adopted. This is done by applying large polymer particles to relatively coarse particles such as sand (0.074 mm to 2 mm), silt (0.005 to 0.074 mm), and clay (0.001 to 2 mm).
For soils with fine particles (such as 0.005 mm), it is better to use a polymer emulsion with a fine particle size. The depth of penetration into the soil can be controlled by adjusting the amount of chemical applied. That is, it can be used as a film type or as a penetrating type that penetrates deeper than 30 cm. The amount of the chemical agent according to the present invention to be applied to soil varies depending on the soil quality and purpose of application, and is difficult to generalize, but in order to fill soil voids and increase consolidation power, it should be approximately 50% of the soil porosity. It is desirable to use the degree as a guideline for spraying. The present invention will be explained below with reference to Examples and Comparative Examples. The symbols used in these have the following meanings. MA: Methyl acrylate EA: Ethyl acrylate BA: Butyl acrylate HA: 2-ethylhexyl acrylate MMA: Methyl methacrylate VAC: Vinyl acetate MAA: Methacrylic acid HEMA: 2-hydroxyethyl methacrylate APS: Ammonium persulfate DM: Dodecyl mercaptan All parts are by weight parts, and all percentages are by weight. Examples 1 to 7, Comparative Examples 1 and 2 400 parts of water was charged into a 5-four-necked flask equipped with a stirrer, thermometer, cooling tube, and dropping funnel, and heated to 80°C.
The temperature rose to . Next, the monomer and DM mixture shown in Table 1 was emulsified with 50 parts of polyoxyethylene nonyl phenyl ether sodium sulfate and 400 parts of water, and APS5
1 part, water was added continuously over 4 hours with an initiator of 95 parts. During this time, the polymerization temperature was maintained at 80 ± 2°C, and after the completion of the dropwise addition, the mixture was stirred at the same temperature for another hour, then cooled to room temperature, adjusted to pH 6.8 with aqueous ammonia, and diluted with an equal amount of water. Examples 1 to 7,
And each drug of Comparative Examples 1 and 2 was prepared. The Tg point of the polymer in these agents is as shown in Table 1, and the soil hardness 1 and 3 days after spraying this agent at 30 kg per 1 m ² on crushed horticultural Akadama soil. The depth of penetration into the soil was measured and the results shown in Table 1 were obtained.

[Table] Example 8 Paper was impregnated with the drug produced in Example 3, 100 seeds of various types were sown thereon, and the mixture was incubated at 25°C for 24 hours.
The number of germination after 72 hours and 168 hours was compared with that in water. The results are shown in Table 2.

[Table] Example 9 Fill each pipe with an inner diameter of 40 mmφ with loam soil and sandy soil to a depth of 15 cm, and apply the chemical of Example 3.
For loam soils, 40g was applied, and for sandy soils, 20g was applied, and the time it took for the chemical to penetrate up to 10cm was measured. The results are shown in Table 3. As a comparison, the drug of Example 3 whose pH had not been adjusted (PH = 2.2) was also tested in the same manner, but in loam soil, the emulsion of the drug coagulated and did not penetrate into the loam soil. The physical properties of the loam soil and sandy soil used in the test are as follows.

【table】

[Table] Example 10 The drug from Example 3 was diluted with water to a concentration of 25%, 15%, and 10%, respectively, and the dilution was carried out in a 6 cm diameter and 5 cm deep
Each was sprayed on loam soil filled in a pipe. Two days after the chemical spraying, the hardness of the soil surface was measured using a Yamanaka soil hardness meter, and the results shown in Table 4 were obtained.

[Table] Example 11 The chemical described in Example 5 was infiltrated into 30 cm of loam soil, and 2 days later, the distribution of consolidation hardness was measured using a Yamauchi soil hardness meter. The results are shown in Table 5.

[Table] Example 12 Loam soil was used as a test material, and the drug concentration of Example 3 was diluted with water to 25%. One cycle was freezing at -4°C for 6 hours and thawing at 25°C for 18 hours.
As a result of carrying out the cycle and examining the surface consolidation hardness,
It was 32cm long. Example 13 Height 3m, watering area 1.5m x 2.0m, watering amount 50~
A soil runoff test was conducted using an artificial rainfall sprinkler system with a rate of 200 mm/hr and an average rainfall amount of 115 mm per sprinkler period. The test soil was loamy soil or sandy soil (same as in Example 9), packed in an experimental box measuring 50 cm long, 25 cm wide and 5 cm deep, with an angle of 30 degrees and three times the amount of the chemical from Example 3. and 5 times diluted, 20 hours after spraying,
I sprinkled water for 2 hours. For comparison, we also conducted a test using only water sprinkling without using any chemicals. The results are shown in Table 6.

[Table] Examples 14 and 15, Comparative Examples 3 and 4 Penetration depth was measured in the same manner as in Example 3, using a polymer emulsion obtained with the same monomer composition as in Example 3, using a drug in which the PH was adjusted with ammonia in various ways. did. The results are shown in Table 7.

[Table] In Table 7, the chemical of Comparative Example 3 (PH=2.3) caused destruction of the emulsion and was unable to penetrate into the soil. Also, in Comparative Example 4 (PH=10.1), the permeability into the soil tends to be slightly inferior to that of Examples 14 and 15, and although it is recognized that this level is generally in a good range, there is a strong ammonia odor. It was determined that there was an environmental problem with the spraying work. Comparative Examples 5 and 6 Emulsion polymerization was carried out in the same manner as in Example 2 except that a cationic emulsifier (stearyltrimethylammonium chloride) was used as the emulsifier to obtain a cationic polymer emulsion. (Comparative Example 5) A spraying test was conducted in the same manner as in Example 2 using this and a commercially available vinyl acetate emulsion (using a nonionic emulsifier) (Comparative Example 6), but both only applied to the surface layer of the soil. The penetration depth was 2 to 3 cm. As is clear from the above Examples and Comparative Examples, the chemical agent according to the present invention causes less scorching on vegetation and has excellent ability to penetrate and fill soil.

Claims (1)

[Claims] 1 Consists of an acrylic polymer dispersion obtained by emulsion polymerization of monomers mainly composed of acrylic esters and/or methacrylic esters in an aqueous medium in the presence of an anionic emulsifier, and the pH of the dispersion is 5 to 5. 9, and the glass transition temperature of the polymer is in the range of -40°C to +20°C.