JPH051315B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel soil improvement material, and more particularly to a soil improvement material using porous particles of cellulose acetate.

In general, the purpose of improving soil can be divided into preventing drying and promoting drainage in grounds, construction sites, etc., and improving air permeability, water permeability, water retention, and preventing caking in plant cultivation. In other words, good soil needs to have all the properties in an appropriate balance, such as air permeability, water permeability, water retention, properties that do not easily consolidate, properties that do not easily increase hardness, and heat insulation properties. There is. For example, clay soil has poor air permeability and water permeability, is extremely easy to consolidate, and tends to become extremely hard in a very short period of time, so it is considered unsuitable for plant cultivation. In addition, sandy soil has too good air permeability and water permeability, has no water retention capacity at all, and dries out extremely quickly. Therefore, not only for plant cultivation, but also on grounds, construction sites, etc., where dust tends to accumulate, it is necessary to mix some kind of improving agent or improve the soil surface.

Particularly with the recent sports boom, the construction of grounds has become popular, but the current situation is that not all of the soil is suitable for grounds. Furthermore, as land prices have soared in recent years, there has been an increasing desire to turn land that is not necessarily suitable for growing plants into fields.

As a solution to these demands, the oldest method used in fields is to use straw,
It involves mixing livestock manure, plants, etc. with soil.
Sprinkling water is the only way to prevent grounds from drying out, and either method is only effective for a very short period of time.

A method of mixing perlite into soil has also been proposed, but since perlite itself is a natural product,
It has disadvantages such as being of inconsistent quality and expensive, and being low in strength and easily turning into powder due to weathering, etc., and losing its effectiveness in a relatively short period of time.

Furthermore, during the cold winter months, soil with poor insulation properties can cause frost columns to form, damaging crops and delaying construction work. For this reason, methods are used to prevent this by spreading straw, or rather, on the soil surface, but these tasks are extremely labor-intensive and have the disadvantage of being extremely expensive, given the rising labor costs. Ta.

Synthetic soil conditioners have recently been developed to improve these drawbacks. For example, there is a method that uses crushed granules of expanded polystyrene, but this method has disadvantages such as polystyrene foam is hydrophobic and has a low water retention capacity, and the foam has a low specific gravity, so it is poorly miscible with soil. There is.

The present inventor discovered that the previously invented porous particles of cellulose acetate have excellent water retention properties and are unaffected by weathering effects, making them suitable as soil improvement materials, leading to the present invention. It is something.

That is, the present invention relates to a soil improvement material that aims to improve the defects of soil itself by mixing porous particles of cellulose acetate with soil.

The porous particles of cellulose acetate used in the present invention preferably have an acetylation degree of 50 to 58%. When the degree of acetylation is less than 50%, it becomes more hydrophilic, absorbs moisture from the soil, and accelerates soil drying. On the other hand, the degree of acetylation
If it exceeds 58%, it becomes difficult to absorb water and the water retention property decreases, so both are unfavorable.

Porous particles can be produced by, for example, a method called a precipitation method, and depending on the conditions at that time, it is possible to make the particles porous, and the particle shape and particle size can also be changed arbitrarily depending on the operating conditions. In the present invention, the pore volume is preferably 0.7 cc/g or more, the shape is spherical, and the particle diameter is preferably 0.5 to 2.0 mm. If the pore volume is small, the water retention property will be poor, which is not suitable for the present invention. Further, a spherical shape is advantageous in terms of strength, surface area, etc. As for crushing strength, if the value is small, it will easily become powder when mixed with soil and will not be able to maintain its original water retention performance. Therefore, the larger the value, the better, preferably 10 kg or more.

Furthermore, it is also possible to use porous particles of cellulose acetate according to the present invention, which are regenerated into cellulose by saponifying only the surface by immersing the surface in a caustic soda solution for a certain period of time. This product has further improved hydrophilicity and can accelerate water absorption rate, which is considered to be advantageous in terms of rapid soil improvement. In this case, if the saponification time is too long, the degree of acetylation will drop too much, which is not suitable for the present invention as described above. For example, the saponification time is preferably 5 to 20 minutes when the concentration of the caustic soda solution is 1%.

The soil improvement material of the present invention accounts for 5 to 30% of the soil.
(Weight ratio) The objective can be achieved by mixing, but a mixing ratio of 10 to 20% is desirable.
This is because if the mixing ratio is too low, the improvement effect will be small.
On the other hand, if the mixing ratio is too high, exceeding 30%, mixing with soil becomes difficult due to the difference in specific gravity, making it impractical.

Furthermore, although the soil conditioner of the present invention is essentially white, it is based on cellulose acetate, which has excellent dyeability, so it can be dyed in any color and used to improve soil for cultivating ornamental plants. As a material, it has the advantage of being colorful.

The present invention will be specifically explained below with reference to Examples.
In addition, the degree of acetylation, pore volume, and crushing strength of Examples were measured by the following methods.

Degree of acetylation: Dry approximately 5 g of the ground sample in a dryer at 100 to 105°C for 2 hours, then weigh accurately. Add 50 c.c. of purified acetone to this sample and after completely dissolving it, add 50 c.c. of 0.2N-NaOH aqueous solution.
cc, then 50c.c. of 0.2N-HC aqueous solution,
0.2N− using phenolphthalein as an indicator
Titrate with NaOH aqueous solution and calculate using the following formula.

Acetylation degree = (A-B) x F x 1.201/sample weight (g)
(%) However, A: Titration number of 0.2N-NaOH aqueous solution (cc) B: Titration number of 0.2N-NaOH aqueous solution in blank test (cc) F: Factor of 0.2N-NaOH aqueous solution Pore volume: Mercury intrusion porosimeter (Carlo Erba The volume of mercury injected at a pressure in the range of 0 to 1000 [Kg/cm ² G] is expressed as the volume per 1 g of sample, which corresponds to the volume of pores of 75 to 75000 Å.

Crushing strength: Using a Monsanto tablet hardness tester (manufactured by Oiwa Yakuhin Kikai Co., Ltd.), calculate the average value of the measured values of 10 particles.

Example 1 Acetylation degree 54.5%, pore volume 0.8cc/g, crushing strength
Cellulose acetate porous particles weighing 15 kg and having a particle size of 2 mm are impregnated with water to a moisture content of approximately 74%, and added to the soil (mountain soil) used for the ground at a weight ratio of 10%.
and 20% were mixed and collected in a shear dish. Water was sprinkled on this to keep the initial moisture constant, and the temperature was 40℃ and 30%.
- When placed in a RH constant temperature and humidity tank and measured the water evaporation rate, soil alone evaporated almost 100% in two days, whereas soil mixed with cellulose acetate particles evaporated 10%.
In the case of mixing, the effect of suppressing dryness was approximately 95% after one week, and in the case of 20% mixing, the effect was 90% after one week.

Example 2 Acetylation degree 53.5%, pore volume 0.7cc/g, crushing strength
Cellulose acetate porous particles weighing 15 kg and having a particle diameter of 1.5 mm were colored with a dye to a desired color and placed on the soil surface of an ornamental flower pot. This material only needs to be watered once every two days even in a relatively dry indoor environment, and it is a beautiful soil improvement material.

Claims (1)

[Claims] 1. A soil improvement material comprising porous particles of cellulose acetate. 2 Porous particles of cellulose acetate have an acetylation degree of 50 to 58
%, a pore volume of 0.7 cc/g or more, and a crushing strength of 10 kg or more.