JP2015042719A - Coating material for protection of ground surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a urethane-based coating material for protection of the ground surface which reacts with a reduced amount of water, compared with conventional coating materials, to form durable hydrous gel and is friendly to the environment, e.g. leaving no unreacted TDI.SOLUTION: A coating material for protection of the ground surface contains a urethane polymer which is a product of a reaction of a polyol component (A) containing a urethane prepolymer having terminal hydroxy groups with an organic polyisocyanate (B) and has terminal isocyanate groups.

Description

  Polyurethane resins have been used in various construction sites, buildings, etc. as water-stopping injecting agents, slope protecting agents, and the like (Patent Documents 1 to 9). In particular, a hydrophilic urethane prepolymer is excellent in economic efficiency because it contains a large amount of water in a small amount of chemical solution to form a gel body, and has been widely used as a coating agent for stabilizing the ground. When hydrophilic urethane prepolymer is used for slope protection or ground coating, it is desirable to be able to consolidate at a lower concentration to spread the chemical solution over a wide range. Especially, the raw material polyether polyol has a higher molecular weight. It must be highly hydrophilic.

However, since polyether polyols increase in hydrophilicity and increase in molecular weight and become thickened or turbid, when they are reacted with polyisocyanates to synthesize urethane prepolymers, prepolymer thickening and precipitation It leads to various troubles such as occurrence.
Therefore, in the conventional formulation, the hydrophilicity was exhibited by using toluene diisocyanate (TDI), which is excellent in hydrophilicity, by suppressing the molecular weight of the raw material polyether polyol and the content of ethylene oxide to a certain level.
However, TDI-based prepolymers have poor resin durability such as weather resistance, and there is a concern that unreacted TDI will flow out into the soil, which may adversely affect the environment. Therefore, in recent years, products made of MDI-based prepolymers based on 4.4-diphenylmethane diisocyanate (MDI) are also being made, but MDI is stronger in oil than TDI, and in order to form a hydrous gel, it is TDI-based. Since the resin concentration has to be increased from that of the prepolymer, it cannot be said that it is reasonable in terms of physical properties and economy.

Japanese Examined Patent Publication No. 62-047210 JP-A-62-265383 Japanese Patent Laid-Open No. 01-299993 JP 07-109369 A JP 09-132633 A JP 2000-345158 A JP 2001-329163 A JP 2002-003821 A JP 2008-179681 A

  The problem to be solved by the present invention is that it reacts with a smaller amount of water compared to conventional urethane prepolymers to form a durable hydrous gel, and also considers the environment such that no unreacted TDI remains. The urethane-based ground surface protecting coating agent is provided.

  As a result of studies by the present inventors, a urethane prepolymer having a terminal hydroxyl group obtained by reacting an excessive amount of a polyether polyol with respect to an equivalent amount of an organic polyisocyanate instead of the polyether polyol usually used in synthesizing a urethane prepolymer. As a raw material, it was found that the problems of the prior art can be solved, and the present invention has been completed.

  That is, the present invention provides a ground surface protecting coating agent comprising a polyol component (A) containing a urethane prepolymer having a terminal hydroxyl group and a urethane prepolymer having a terminal isocyanate group which is a reaction product of the organic polyisocyanate (B). It is about.

  The urethane prepolymer having a terminal hydroxyl group used in the present invention is obtained by reacting polyether polyol (a) and organic polyisocyanate (b) so that (a) is excessive with respect to the equivalent of (b). Can be obtained.

  Examples of the polyether polyol (a) include compounds having a structure in which an alkylene oxide is added to an initiator such as a compound having two or more active hydrogen atoms (for example, water, polyhydric alcohol, polyhydric phenol, amine, etc.) A mixture is mentioned.

  Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3- and 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, glycerin, diglycerin, trimethylolpropane, Examples include sorbitol, pentaerythritol, and cyclohexanedimethanol. Examples of the polyhydric phenol include monocyclic polyhydric phenols such as pyrogallol, hydroquinone, resorcin, and phloroglucin; and bisphenols such as bisphenol A and bisphenol sulfone.

  Examples of the alkylene oxide include ethylene oxide, propylene oxide, 1,2-, 1,3-, 1,4- or 2,3-butylene oxide, and combinations of two or more thereof (block or random addition). It is done. Among these, ethylene oxide and propylene oxide are preferable, and the ratio of ethylene oxide and propylene oxide in the polyoxyalkylene chain is 90% or more of the total by mass ratio, and the ratio of ethyleneoxy group and propyleneoxy group is mass ratio. 50:50 to 100: 0 is preferable, and 60:40 to 90:10 is more preferable. The number average molecular weight of the polyether polyol is preferably 1000 to 8000.

Although organic polyisocyanate (b) is not specifically limited, Specifically, the following can be used. For example, an aromatic polyisocyanate having 1 to 20 carbon atoms (excluding carbon in the isocyanate group, the same applies hereinafter) [1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate ( TDI), 4,4′- or 2,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate, 4,4 ′, 4 ″ -triphenylmethane triisocyanate, m- or p-isocyanato Phenylsulfonyl isocyanate and crude MDI], aliphatic polyisocyanate having 2 to 18 carbon atoms [ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 2,2,4-trimethylhexane diisocyanate, lysine diisocyanate Nate, 2,6-diisocyanatomethyl caproate, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate, etc.], alicyclic polyisocyanate having 8 to 15 carbon atoms [isophorone diisocyanate ( IPDI), dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis (2-isocyanatoethyl) 4-cyclohexene-1,2-dicarboxylate, etc.], carbon number 8 To 15 araliphatic polyisocyanates [xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate (TMXDI), etc.], and modifications of these polyisocyanates (carbodiimide groups, uretdio Modified group containing a ureton group, a uretoimine group, a urea group, a burette group, an isocyanurate group, and the like.
Among these, aliphatic or aromatic polyisocyanates (particularly diisocyanates) are preferable, and TDI, HDI, and XDI are more preferable in that gelation and thickening hardly occur during the reaction with the polyether polyol (a).

  The synthesis of the urethane prepolymer having a terminal hydroxyl group was carried out by charging the reaction apparatus with polyether polyol (a) and organic polyisocyanate (b) so that (a) would be excessive, and then reacting at 60 to 160 ° C. Can be done. At that time, a tin-based catalyst such as monobutyltin oxide, dibutyltin oxide, tetraoctyltin, dioctyltin oxide, dibutyltin laurate, dioctyltin laurate, or the like can be used as necessary. Here, (a) and (b) are urethane prepolymers having a terminal hydroxyl group with a molecular weight intended to be reacted so that the OH / NCO equivalent ratio is 2.0 to 3.0. Even when TDI is used as b), it is preferable in that the residual amount is small. Moreover, 1000-20000 are preferable and, as for the number average molecular weight of the urethane prepolymer which has a terminal hydroxyl group, 2000-12000 are more preferable.

  As a polyol component (A), in addition to what consists only of urethane prepolymer which has a terminal hydroxyl group, other polyols may be included in the range which does not impair the effect of this invention. Examples of other polyols include polyester polyols and polycarbonate polyols in addition to the above-mentioned (a) polyether polyols. Moreover, a diluent may be included for viscosity reduction.

  The urethane prepolymer (U) having a terminal isocyanate group of the present invention can be obtained by reacting the polyol component (A) and the organic polyisocyanate (B) by a conventional method. As the organic polyisocyanate (B), the same organic polyisocyanate (b) used in the synthesis of the urethane prepolymer having a terminal hydroxyl group can be used, but MDI is preferred. The synthesis of the terminal isocyanate group-containing urethane prepolymer can be carried out in the same manner as the synthesis of the terminal hydroxyl group-containing urethane prepolymer, except that the organic polyisocyanate is reacted in excess of the equivalent of the polyol component (A).

  The urethane prepolymer having a terminal isocyanate group reacts with water in a short time to form a durable hydrous gel. Therefore, by spraying the urethane prepolymer of the present invention together with water, it can be suitably used as a coating agent for protecting an unstable ground surface such as a slope. Specific applications include slope erosion prevention, slope protection, dust proofing, flying sand prevention, or contaminated soil film.

A diluent can be blended in the ground surface protecting coating agent and polyol component (A) of the present invention, if necessary. Specific examples of the diluent include gamma-butyl lactone, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, 2oxo-4methyl-1, 3 dioxolane, methyl acetyl ricinolate, butyl acetyl ricinolate, Dimethyl glutarate, dimethyl succinate, dimethyl adipate or mixtures thereof. The diluent is preferably used at a concentration of 10 to 50% by mass of the total amount from the viewpoint of viscosity and water compatibility.
The isocyanate group content (NCO%) in the urethane prepolymer having a terminal isocyanate group is preferably 1 to 15%, more preferably 2 to 13%. When NCO% is in this range, the handling property such as viscosity is good and the minimum gelation concentration is low, which is preferable from the viewpoint of cost.

  As an application method when using the ground surface protecting coating agent of the present invention, there is a method of mixing with water and spraying and spraying on the ground surface with a sprayer or sprayer. The drug concentration at the time of application is preferably about 5%, but is not limited thereto.

Hereinafter, the present invention will be described by way of examples. However, the present invention is not limited to these examples and comparative examples. In this example, the number average molecular weight was measured using GPC.
<GPC measurement conditions>
Device: Tosoh HLC-8120GPC
Solvent: Tetrahydrofuran Flow rate: 0.6 ml / min
Temperature: 40 ° C
Sample concentration: 0.1%
Sample injection volume: 20 μl
Detector: RI

<Synthesis of a polyol component (A) containing a urethane prepolymer having a terminal hydroxyl group>
Synthesis example 1
Polypropylene polyol (a) dipropylene glycol ethylene oxide (EO) propylene oxide (PO) adduct (number average molecular weight 3000, EO: PO) as a polyether polyol (a) in a synthesis device with an internal volume of 0.8 L equipped with a stirrer, thermometer and temperature controller (Mass ratio) = 85: 15): 450 g of a-1 was charged. Next, 11.7 g of TDI (Nihon Polyurethane Co., Ltd. Coronate T-80) was added to the apparatus as an isocyanate component, and the temperature was raised to 110 to 115 ° C. and reacted for 3 hours. The obtained urethane prepolymer reaction liquid confirmed that the isocyanate group had disappeared. The amount of isocyanate remaining in the polymer was calculated by adding excess dibutylamine according to a conventional method, reacting the isocyanate group with dibutylamine, and then distilling the remaining dibutylamine by a back titration method using hydrochloric acid. . Further, it was confirmed by gas chromatography that the residual TDI was 0.1% or less. Finally, 115 g of gamma-butyl lactone was added as a diluent to obtain polyol component A-1.

Synthesis Examples 2-4
Polyol components A-2 to A-4 were obtained in the same manner as in Synthesis Example 1 except that the polyether polyol (a) and the organic polyisocyanate (b) described in Tables 1 and 2 were used.

<Production of urethane prepolymer (U) having terminal isocyanate group>
Production Examples 1-7
Charge a polyol component (A) containing a urethane prepolymer having a terminal hydroxyl group and an organic polyisocyanate (B) in a mass ratio shown in Table 3 to a 0.8 L internal synthesizer equipped with a stirrer, thermometer and temperature controller. The temperature was raised to 130-135 ° C. and the reaction was carried out for 2 hours. Furthermore, the diluent was mix | blended and the urethane prepolymer composition U-1 to U-7 which has a terminal isocyanate group was obtained.

Comparative production examples 1-4
Terminal isocyanate group-containing urethane prepolymer compositions E-1 to E-4 were obtained in the same manner as in Production Example 1 except that polyether polyols a-1 and a-2 were used as the polyol component (A).

[Performance evaluation]
The urethane prepolymer compositions obtained in Production Examples 1 to 7 and Comparative Production Examples 1 to 4 were subjected to the tests (1) to (6) below. The results are shown in Table 4.
(1) Viscosity The viscosity at 20 ° C. was measured using a B-type rotational viscometer at a rotation speed of 60 rpm.
(2) Curing Performance at 10% Concentration 45 g of water was put into a 100 ml death cup, 5 g of the urethane prepolymer composition produced was added thereto, and the curing time was measured.
(3) Curing Performance at 5% Concentration 95 g of water was placed in a 200 ml death cup, 5 g of the urethane prepolymer composition produced was added thereto, and the curing time was measured.
(4) Durability of hardened | cured material The hardened | cured material of (2) was demolded, it immersed in 1% sodium hydroxide aqueous solution, and the external appearance after one month and the presence or absence of the decomposition product were observed. The case where there was no change in the appearance and no decomposition product was evaluated as “◯”, and the case where there was a change in the appearance and the decomposition product was generated was evaluated as “X”.
(5) Sand coating test (weather resistance)
A baked sand (Toyoura standard sand) was spread over a panel of 50 cm × 20 cm, assuming a slope, with a thickness of 1 cm, tilted so that the slope was 36 °, and the short side was fixed to the ground (see FIG. 1). A urethane prepolymer composition diluted with water to a concentration of 5% was sprayed at 0.4 ml / cm ² and allowed to stand for 24 hours to prepare a sand gel. This was left outdoors for one month and a weather resistance test was conducted. The ratio of the sand gel remaining on the control panel was calculated based on the mass of the sand gel before the test. The evaluation of the measurement result is that the ratio of the remaining sand gel is 90% or more is “◎”, 80% or more and less than 90% is “◯”, and less than 80% is “Δ”, and the urethane prepolymer composition is not cured. When it was impossible, it was set as “x”.
(6) Coat test on sand (rain resistance)
A rain test was conducted by flowing water from the top to a sand gel manufactured in the same procedure as in (5) at a rate of 100 mm / h of precipitation. The ratio of the sand gel remaining on the control panel was calculated based on the weight of the sand gel before the test. The evaluation of the measurement result is that the ratio of the remaining sand gel is 90% or more is “◎”, 80% or more and less than 90% is “◯”, and less than 80% is “Δ”, and the urethane prepolymer composition is not cured. When it was impossible, it was set as “x”.

  As shown above, the ground surface protective coating agent according to the present invention has (1) viscosity, (2) curing performance, (3) low concentration curability, (4) durability of the resin (5) long-term weather resistance. And (6) It turns out that it is excellent in both rain resistance.

It is a figure which shows the method of the coat | court test (weather resistance) to sand. It is a figure which shows the method of the coat test (rain resistance) to sand.

Claims (3)

  A ground surface protecting coating agent comprising a polyol component (A) containing a urethane prepolymer having a terminal hydroxyl group and a urethane prepolymer (U) having a terminal isocyanate group which is a reaction product of the organic polyisocyanate (B).   The urethane prepolymer having a terminal hydroxyl group is obtained by reacting a polyether polyol (a) and an organic polyisocyanate (b) so that the OH / NCO equivalent ratio is 2.0 to 3.0. The ground surface protective coating agent according to claim 1.   The polyether polyol (a) has a number average molecular weight obtained by addition polymerization of ethylene oxide and propylene oxide in a weight ratio of 50:50 to 100: 0 to a compound having two or more active hydrogen atoms. The ground surface protecting coating agent according to claim 2, which is a polyether polyol of 1000 to 8000.

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