JP2005060467A - Gel composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a gel composition which is hardly influenced by the pH, or the like, of the soil, can stably fix the ground, and does not elute a harmful substance causing a carcinogenic problem, or the like, when injected into the ground or within the time from its injection to gelation. <P>SOLUTION: This gel composition contains a carboxyl-group-containing polyvinyl alcohol (A) having a polymerization degree of 300-3,300, a saponification number of 80 mol% or higher, and a content of carboxyl-group-containing vinyl unit of 0.2-20 mol% and a cationic-group-containing polymer (B) having a total amine value of 100 (mg KOH/g) or higher in a wt. ratio (A/B) of (30/70)-(90/10). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gel-like composition mainly used for water stoppage and vibration prevention as a backfilling material for hollows and voids in natural grounds and as a filler for shield segments, and in particular, filled in these voids. Later, the present invention relates to a gel composition characterized by gelling and fixing the ground.

  In the vicinity of water intakes such as river dikes, voids may occur in the ground due to erosion by running water. In tunnel construction, a cavity may be generated between the tunnel wall and the ground during construction or after construction. At that time, it is necessary to fill the cavities with a backfill material to prevent water from the river bank and to fix the tunnel wall. Conventional backfilling materials include cement that has been thickened by adding a superabsorbent resin (see, for example, Patent Document 1), and water glass that has been accelerated by hardening (see, for example, Patent Document 2). ) Etc. were proposed.

  However, since these cement-based backfill materials do not have flexibility and toughness, they are damaged when subjected to vibrations due to earthquakes, consolidation settlements, traffic, etc., and have little vibration absorption. There was a problem that the ground itself was damaged. Moreover, since it does not have swelling property, there also existed a problem that the space | gap once generate | occur | produced was not filled up as it was. In order to solve such problems, organic backfilling materials in which soil particles are fixed with a resin or a gel-like substance have been proposed so far, for example, acrylamide-based, acrylate-based, lignin sulfonic acid-based materials. In general, a method using a phenol resin is generally used. However, these backfill materials have a problem that they are greatly restricted in terms of toxicity and cost.

Therefore, various studies have been made on the use of polyvinyl alcohol (hereinafter referred to as PVA) as a non-toxic backing material. For example, a polymerizable α, β-unsaturated compound and / or conjugated diene compound is grafted onto PVA. Modified and added with copper, calcium, zinc, etc. (for example, see Patent Document 3), containing PVA and a boric acid compound in the presence of alkali and glycols (for example, see Patent Document 4), PVA And a compound having a methylol group gelled (for example, see Patent Document 5).
JP-A-10-237446 (paragraph number 0069 and others) JP 11-061123 A (paragraph number 0025 and others) Japanese Patent Laid-Open No. 51-68918 (the second page, upper right column, lines 11 to 19) JP-A-52-1941 (Specification, page 11, upper right column, line 6 to lower left column, line 1) JP 2002-371278 A (paragraph number 0009 and others)

  The backfilling material using PVA described in Patent Documents 3 to 4 is a material in which a void in the ground is filled and fixed with a PVA polymer and a metal represented by copper or a chelate formed with boric acid. However, this chelate is not strong in terms of chemical bonding, and its bond is easily broken under the influence of soil pH and the like, so that the effect of fixing the ground is not stably maintained. doing. In addition, the backfill material obtained by gelling the compound having PVA and a methylol group described in Patent Document 5 has a water-soluble and low molecular weight compound having a methylol group, and the compound has confirmed carcinogenicity. Since aldehydes are contained, aldehydes may be eluted during injection into the ground or between injection and gelation, and the problem of toxicity has not been completely solved.

  As a result of intensive studies to solve the above problems, the present inventors have developed a gel-like composition having a carboxyl group-containing PVA and a cationic group-containing polymer, the composition and amount of which are specified as a backfill material. It has been found that the above-mentioned problems can be solved by using it.

  That is, the present invention relates to a carboxyl group-containing polyvinyl alcohol (A) having a polymerization degree of 300 to 3300, a saponification degree of 80 mol% or more and a carboxyl group-containing vinyl unit content of 0.2 to 20 mol%, and a total amine value of 100 (mg The present invention relates to a gel composition characterized by having a cationic group-containing polymer (B) of KOH / g) or more in a content weight ratio (A / B) of 30/70 to 90/10.

  The gel composition of the present invention is not easily affected by the pH of the soil, can stably fix the ground, and is harmful to carcinogenic problems during injection into the ground or from injection to gelation. It has the effect that the substance does not elute.

  The content weight ratio (A / B) of the carboxyl group-containing PVA (A) and the cationic group-containing polymer (B) in the present invention is preferably 30/70 to 90/10, preferably 40/60 to 80/20. good. When the weight ratio of the carboxyl group-containing PVA is smaller than 30, the reaction points between the carboxyl group and the cationic group are reduced, and the durability of the gel composition is lowered. On the other hand, if the content weight ratio of the cationic group-containing polymer is less than 10, the reaction point between the carboxyl group and the cationic group is reduced, and the durability of the gel composition is lowered.

  The degree of polymerization of the carboxyl group-containing polyvinyl alcohol used in the present invention is in the range of 300 to 3300, preferably in the range of 500 to 2400. If the degree of polymerization is small, the durability of the gel composition will be low, and if it is high, the viscosity of the aqueous solution will be high and it will not be possible to transport with a pump.

  The saponification degree of the carboxyl group-containing polyvinyl alcohol used in the present invention is 80 mol% or more, preferably 90 mol% or more. If the degree of saponification is low, the solubility of the gel-like composition in water increases, and there is a drawback that elution after gelation increases.

  The carboxyl group-containing polyvinyl alcohol used in the present invention has a carboxyl group-containing vinyl unit content of 0.2 to 20 mol%, preferably 1 to 15 mol%. When the carboxyl group-containing vinyl unit content is low, the durability of the gel composition is low, and conversely, when it is high, it is difficult to produce industrially.

  The carboxyl group-containing polyvinyl alcohol used in the present invention is produced by a known method. That is, the method etc. which are obtained by copolymerizing an aliphatic vinyl ester and a carboxyl group-containing unsaturated vinyl compound and saponifying are mentioned.

  As the aliphatic vinyl ester used in this method, for example, aliphatic vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, and vinyl trifluoroacetate are publicly known such as solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization and the like. It can be obtained by copolymerizing with a carboxyl group-containing unsaturated vinyl compound by a polymerization method, dissolving the obtained polymer in an alcohol such as methanol, adding an alkali catalyst to saponification, and drying.

  Examples of the carboxyl group-containing unsaturated vinyl compound include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, monoalkyl maleate, and monoalkyl fumarate that can be converted to carboxyl groups by saponification after copolymerization. Saturated carboxylic acids or these unsaturated alkyl esters, acrylamide, methacrylamide and the like can be mentioned.

  The total amine value of the cationic group-containing polymer used in the present invention is preferably 100 (mg KOH / g) or more, and preferably 200 (mg KOH / g) or more. When the amine value is small, the durability of the gel composition is lowered.

  The cationic group-containing polymer used in the present invention is not particularly limited as long as it contains a cationic group in the molecule, but polyallylamine, polyvinylpyrrolidone, polyvinylpyridine, polyethyleneimine, polyamide epichlorohydrin, and polyamide polyamine are preferably used. Is done.

  The gel composition in the present invention is a solution in which an aqueous solution before gelation is poured into a void portion of the ground and then gelled to fill the void portion without a gap and stably fix the ground.

  In order to inject the gel-like composition in the present invention into the void portion of the ground, a conventionally known pump may be used. There are no particular restrictions on the type of pump, but a squeeze-type pump is suitable for transporting high-viscosity slurry and is preferably used.

  The gel composition of the present invention can also be mixed with a chelate compound of a metal such as titanium, zirconium, vanadium as a curing agent as long as the object of the present invention is not impaired.

  Hereinafter, the present invention will be described more specifically with reference to examples. “Parts” and “%” are based on weight unless otherwise specified.

"Example 1"
As shown in the column of the constitution in Table 1, carboxyl group-containing polyvinyl having 5 mol% carboxyl group units, 96% saponification degree, and 1700 polymerization degree, obtained by copolymerization and saponification of vinyl acetate and dimethylmaleic acid. 30 parts of alcohol (A) was added and dissolved in 370 parts of pure water heated to 90 ° C. to obtain 400 parts of a polyvinyl alcohol aqueous solution having a solid content of 10%. The solid content (A) of the obtained PVA aqueous solution and the polyethyleneimine solid content (B) were mixed so as to be 50/50 to obtain a gel composition. The obtained gel-like composition was measured for pumping property, gelation time, and water resistance after gelation. The results are shown in the characteristic column of Table 1.

"Examples 2 to 5"
Using the carboxyl group-containing polyvinyl alcohol and the cationic group-containing polymer shown in Table 1, a gel composition was prepared in the same manner as in Example 1, and the pumping property, gelation time, and water resistance after gelation were prepared. The properties were measured in the same manner as in Example 1. The results are shown in the characteristic column of Table 1.

"Comparative Examples 1-6"
As shown in the column of the configuration of Table 2, a gel composition was prepared in the same manner as in Example 1 using polyvinyl alcohol and a cationic group-containing polymer, and the pumpability, gelation time, and gelation were The subsequent water resistance was measured in the same manner as in Example 1. The results are shown in the characteristic column of Table 2.

"Measurement method and evaluation"
Pumpability: Using a squeeze-type pump, the transportability of the gel composition was confirmed, and those that could be transported were marked with ◯, and those that could not be transported were marked with ×.
Gelation time: The time until the gel-like composition was dropped into a beaker containing water in advance and no longer separated was measured.
Water resistance: The gel composition was placed in a beaker containing water and the state of the gel was visually observed. The one that did not dissolve was ○, the one that was slightly dissolved was Δ, the one that was completely dissolved The stuck one was marked with x.

Claims (3)

  A carboxyl group-containing polyvinyl alcohol (A) containing a vinyl alcohol unit, a carboxyl group-containing vinyl unit, an aliphatic vinyl ester unit, and a cationic group-containing polymer (B) having a total amine value of 100 (mg KOH / g) or more, A gel composition having a weight ratio (A / B) of 30/70 to 90/10.   The carboxyl group-containing polyvinyl alcohol (A) has a polymerization degree of 300 to 3300, a saponification degree of 80 mol% or more, a carboxyl group-containing vinyl unit content of 0.2 to 20 mol%, and a cationic group-containing polymer (B). The gel composition according to claim 1, which is one or a mixture of two or more selected from polyallylamine, polyvinylpyrrolidone, polyvinylpyridine, polyethyleneimine, polyamide epichlorohydrin, and polyamide polyamine.   The gel-like composition according to claim 1 or 2, wherein after filling the void portion of the ground with the composition, the ground is fixed by gelation.