Two-component epoxy resin composition for surface preparation and three-component epoxy resin composition for surface preparation

Abstract

To provide an epoxy resin composition for surface preparation that is water-based, free from volatile organic solvents, yet exhibits excellent paint properties such as drying and curing characteristics. Furthermore, to provide an epoxy resin composition whose properties can be applied to applications other than paints. [Solution] A two-component epoxy resin composition for surface preparation comprising a main component containing at least a water-dispersible epoxy resin, water, and alumina cement whose hydration reaction is blocked; and an auxiliary component containing an epoxy resin curing agent for curing the epoxy resin and a basic aqueous solution for releasing the blockage of the hydration reaction of the alumina cement. Furthermore, a three-component epoxy resin composition for surface preparation comprising a solvent containing water in addition to these main and auxiliary components.

Description

[Technical Field]

[0001] The present invention relates to a two-component epoxy resin composition for surface preparation and a three-component epoxy resin composition for surface preparation. [Background technology]

[0002] Traditionally, epoxy resin paints, primarily composed of aromatic epoxy resins such as bisphenol A and bisphenol F epoxy resins, have been widely used as floor coatings for factories due to their excellent durability, chemical resistance, and, as a primer, their superior concrete impregnation and adhesion. Conventionally, epoxy resin paints have generally been made less viscous by incorporating volatile organic solvents to improve paintability and concrete impregnation.

[0003] Furthermore, in order to ensure the shelf life (pot life) of epoxy resin paints until use, a paint composition in which the epoxy resin and the curing agent that hardens the epoxy resin are separated into two components has been proposed and is being used.

[0004] In response to the recent demand for lower VOC content, there has long been a call for a shift from organic solvent-based epoxy resin paints to water-based epoxy resin paints (see, for example, Patent Document 1). However, the demand for organic solvent-based epoxy resin paints, which excel in paint properties such as drying and curing properties, and film properties such as durability and chemical resistance, remains high.

[0005] Therefore, it is desirable to solve the problems of organic solvent-based epoxy resin coatings derived from volatile organic solvents, while also improving the coating properties such as poor drying under high humidity conditions, delayed curing at low temperatures, film thickness reduction due to water evaporation, concrete impregnation, durability, and chemical resistance, which are challenges of water-based epoxy resin coatings.

[0006] Incidentally, while white Portland cement and alumina cement are used as inorganic binders in water-based paints, they are inferior in terms of physical properties such as thinning, stain resistance, and impact resistance, as well as handling properties such as paintability, color matching, and storage stability. Therefore, they are not commonly used as finishing materials that can be easily applied with rollers, for example. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International release 2020 / 110601 [Overview of the project] [Problems that the invention aims to solve]

[0008] The present invention aims to provide an epoxy resin composition for surface preparation that is a water-based paint that does not contain volatile organic solvents, yet exhibits excellent paint properties such as drying and curing properties. Furthermore, it aims to provide an epoxy resin composition for surface preparation whose properties can be applied to applications other than paints. [Means for solving the problem]

[0009] The above objective is achieved by the following embodiments of the present invention. That is, the embodiments of the present invention are as follows. <1> A main component comprising at least a water-dispersible epoxy resin, water, and alumina cement in which the hydration reaction is blocked, An epoxy resin curing agent for curing the epoxy resin, and an auxiliary agent comprising a basic aqueous solution for releasing the blockage of the hydration reaction of the alumina cement, A two-component epoxy resin composition for surface preparation.

[0010] <2> In the coating solution prepared by mixing the main agent and the auxiliary agent, the water content is 5 to 30% by mass, and the curing agent forming component content is 85 to 100% by mass. <1> A two-component epoxy resin composition for surface preparation as described above.

[0011] <3> The two-pack epoxy resin composition for substrate conditioning according to <1>, wherein the epoxy resin is a self-emulsifying liquid epoxy resin.

[0012] <4> The two-pack epoxy resin composition for substrate conditioning according to <1>, wherein the epoxy resin curing agent is a polyamine.

[0013] <5> The two-pack epoxy resin composition for substrate conditioning according to <1>, which further contains coarse aggregate and is used as a resin paste material or a resin mortar material.

[0014] <6> A base agent comprising at least a water-dispersible epoxy resin, water, and alumina cement with its hydration reaction blocked, A secondary agent comprising an epoxy resin curing agent for curing the epoxy resin, and a basic aqueous solution for unblocking the hydration reaction of the alumina cement, A solvent comprising water, A three-pack epoxy resin composition for substrate conditioning, comprising the above components.

[0015] <7> The three-pack epoxy resin composition for substrate conditioning according to <6>, wherein when the base agent, the secondary agent and the solvent are mixed to prepare a coating liquid, the water content in the coating liquid is 32 to 60 mass%, and the content of the cured product-forming component is 50 to 75 mass%.

[0016] <8> The three-pack epoxy resin composition for substrate conditioning according to <6>, wherein the epoxy resin is a self-emulsifying liquid epoxy resin.

[0017] <9> The three-pack epoxy resin composition for substrate conditioning according to <6>, wherein the epoxy resin curing agent is a polyamine. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a two-component epoxy resin composition for surface preparation that is a water-based paint that does not contain volatile organic solvents, yet exhibits excellent paint properties such as drying properties and curing properties. Furthermore, it is possible to provide a three-component epoxy resin composition for surface preparation that can be diluted with water as needed to adjust to any desired thickness. In addition, it is possible to provide a two-component epoxy resin composition whose properties can be applied to applications other than paints. [Brief explanation of the drawing]

[0019] [Figure 1] This is a schematic diagram illustrating the state of the main component and auxiliary component in the two-component epoxy resin composition for surface preparation according to this embodiment. [Figure 2] This is a schematic diagram illustrating the state of a coating film formed by a coating solution prepared using the two-component epoxy resin composition for surface preparation according to this embodiment. [Figure 3] This is an optical microscope image (100x magnification) of a cross-section of a coating film formed by a coating solution prepared using the two-component epoxy resin composition for surface preparation according to the example. [Modes for carrying out the invention]

[0020] The two-component epoxy resin composition and the three-component epoxy resin composition for surface preparation of the present invention (hereinafter sometimes simply referred to as "epoxy resin composition") were developed for paint applications, but due to their unique curing mechanism and properties, they can be applied to a variety of uses other than paint. In the following embodiments, the use as a paint will be described primarily, and applications to other uses will be described together later.

[0021] <Embodiments of paint application> The following describes an epoxy resin composition according to one embodiment of the present invention for use in paints. The two-component epoxy resin composition for surface preparation according to this embodiment comprises the following main component and auxiliary component.

[0022] • Main component: at least a water-dispersible epoxy resin, water, and alumina cement with blocked hydration reaction. • Auxiliary components: An epoxy resin hardener that hardens the epoxy resin contained in the main component, and a basic aqueous solution that releases the blockage of the hydration reaction of the alumina cement contained in the main component.

[0023] Furthermore, the three-component epoxy resin composition for surface preparation according to this embodiment contains the following solvent in addition to the main component and auxiliary component. • Solvent…a liquid containing water

[0024] In addition to the essential components listed above, other components included in the epoxy resin composition according to this embodiment may be appropriately blended, either in combination with at least one of these components or as separate agents. Hereinafter, we will focus on two-component epoxy resin compositions consisting of a main component and an auxiliary component, or three-component epoxy resin compositions further containing a solvent (when two-component and three-component types are not distinguished, the term "epoxy resin composition" will be used), describing the essential components contained in the main component, the auxiliary component, and the solvent, respectively, followed by a description of the other components.

[0025] [(1) Main ingredient] In the epoxy resin composition according to this embodiment, (1) the main component includes, as essential components, a self-emulsifying epoxy resin, water, and alumina cement.

[0026] (Epoxy resin) Examples of epoxy resins used in this embodiment include bisphenol-type epoxy resins such as bisphenol A, bisphenol F, bisphenol S, and halogenated bisphenol A; biphenyl-type epoxy resins; alicyclic epoxy resins; ester-type epoxy resins such as dibasic acids; terpene diphenol-type epoxy resins; and the like. Phenolic novolac epoxy resins; alkylphenol novolac epoxy resins such as cresol novolac epoxy resins; novolac epoxy resins of bisphenol A; and the like can also be used. These epoxy resins may be used individually or in combination of two or more.

[0027] There are no particular limitations on the method for producing the epoxy resin used in this embodiment, but examples include direct and indirect synthesis methods for bisphenol A type epoxy resin and bisphenol F type epoxy resin, a method of obtaining a hydroxyl group-introduced epoxy resin by reacting an epoxy resin with an aliphatic monocarboxylic acid, and a method of obtaining a hydroxyl group-introduced epoxy resin by reacting an epoxy resin with monophenols, etc.

[0028] In this embodiment, any epoxy resin that is water-dispersible can be used, including self-emulsifying epoxy resins and non-self-emulsifying epoxy resins. When using a non-self-emulsifying epoxy resin, it can be emulsified by mixing it with an emulsifier or a self-emulsifying resin and then dispersed in water. However, it is preferable to use a self-emulsifying epoxy resin because forced emulsification using an emulsifier requires stirring with shear force, making the process complicated, and it is difficult to ensure properties such as water resistance even when forced emulsification is performed using an emulsifier. Furthermore, since this is the opposite of general emulsification and involves dispersing water in the epoxy resin, it is preferable to use a self-emulsifying epoxy resin in order to maintain the uniformity of the paint and improve the uniformity of the formed coating film.

[0029] Self-emulsifying epoxy resins are epoxy resins that, upon contact with water, spontaneously form a dispersion or emulsion without the need for special emulsifiers or dispersants. Specific examples of self-emulsifying epoxy resins include those in which a hydrophilic portion has been introduced; for example, epoxy resins having a hydrophilic portion within the molecule. Examples of such hydrophilic portions include ionic hydrophilic groups and nonionic polyalkylene oxide skeletons.

[0030] Epoxy resins having a polyalkylene oxide skeleton in their molecules can be obtained, for example, by reacting an epoxy resin with a polyalkylene glycol by a conventional method under conditions of excess epoxy equivalent. The polyalkylene glycol used in this process is not particularly limited, and examples include alkylene glycols such as ethylene glycol, propylene glycol, and butylene glycol, polyethylene glycols such as diethylene glycol and triethylene glycol, and polypropylene glycols with a degree of polymerization of 2 to 10.

[0031] (water) (1) There are no particular restrictions on the water used as the main ingredient; tap water, industrial water, river water, groundwater, deionized water, pure water, etc., can all be used. As long as the salt and sulfur content is not extremely high, it can be used without any problems, but of course, it is preferable to use water with fewer impurities.

[0032] (Alumina cement) There are no particular restrictions on the alumina cement used in this embodiment; for example, any of the five types of alumina cement specified in Japanese Industrial Standard JIS R2511 (abolished in 2000) can be used.

[0033] The alumina cement used in this embodiment has its hydration reaction blocked. A blocking agent (also called a "hydration inhibitor") is used to block the hydration reaction of alumina cement. It is known that alumina cement can stop hydration and stabilize the turbidity by using such a blocking agent.

[0034] Blocking agents that inhibit the hydration reaction of alumina cement are substances whose aqueous solutions exhibit acidity. Specific blocking agents include metaphosphoric acid, phosphorous acid, phosphoric acid, phosphonic acid, and phosphorus-containing compounds that can produce these phosphorus compounds by reacting with water; oxycarboxylic acids and their salts; polyacrylic acid and its derivatives; acrylic acid salts; chelating agents; condensed phosphates; aluminum phosphate, and boric acid. These can be used individually or in combination of two or more.

[0035] The mechanism by which the blocking agent blocks the hydration reaction of alumina cement is thought to be as follows: When alumina cement comes into contact with water, it immediately reacts with Ca 2+ and Al 3+ As ions dissolve, the pH of the water rises. Then, at a certain pH level, alumina cement hydrate precipitates. However, if an acidic blocking agent is present, the dissolved Ca 2+ Because the substances are captured and the rise in pH is suppressed, the water is maintained at a slightly acidic level, thus inhibiting the progress of the hydration reaction of alumina cement.

[0036] On the other hand, the hydration reaction of alumina cement induces the gelation of aluminum hydroxide. This gelled aluminum hydroxide deposits and coats the surface of the alumina cement, and remains stably present on the surface of the alumina cement when the water is maintained at an acidic level. Therefore, it is presumed that the hydration reaction of the alumina cement is stopped. However, this mechanism of hydration cessation is merely a hypothesis, and this embodiment is not limited by this mechanism.

[0037] In this embodiment, the amount of blocking agent added mainly depends on the acidity of the blocking agent and the amount of alumina cement in the main component. In practice, it is preferable to adjust the amount of blocking agent added so that the pH of the main component is 2 to 7, and more preferably 3 to 6.

[0038] If the pH of the main component becomes too high, there is a concern that the hydration-stopping effect will be insufficient, which may result in poor shelf life. On the other hand, if the pH of the main component becomes too low, the main component may generate heat and enter a pseudo-coating state, in which case shelf life is also likely to be insufficient. This pseudo-coating phenomenon is thought to be caused by a direct chemical reaction between the alumina cement and the acid.

[0039] The main component of the epoxy resin composition according to this embodiment can be prepared by mixing the above essential components with other components to be added as appropriate, as described later, and stirring thoroughly using, for example, a general rotary stirrer, to prevent unevenness in concentration.

[0040] [(2) Adjuncts] The (2) auxiliary component in the epoxy resin composition according to this embodiment includes an epoxy resin curing agent and a basic aqueous solution as essential components.

[0041] (Epoxy resin curing agent) The epoxy resin curing agent used in this embodiment (hereinafter sometimes simply referred to as "curing agent") can be any agent commonly used as a curing agent for epoxy resins. Specific curing agents include, for example, polyamidoamines, polyamines such as aliphatic polyamines and modified polyamines, epoxy resin amine adducts, aromatic amines, hydrazides, dicyandiamides, imidazoles, tertiary amines, acid anhydrides, phenolic resins, urea resins, resol resins, amino resins, ketimines, acid-terminated polyester resins, isocyanates, and blocked isocyanates. Multiple curing agents may be used in combination depending on the purpose. Among these, polyamines are preferred as curing agents in this embodiment in terms of reaction rate with epoxy resin at room temperature and its control, viscosity when mixed with epoxy resin and its control, and mixing stability with alkaline aqueous solutions.

[0042] (Basic aqueous solution) The basic aqueous solution used in this embodiment is a material that releases the blockage of the hydration reaction of the alumina cement contained in the main component and restores the progress of the hydration reaction, and can be referred to as a hydration initiator in contrast to the blocking agent contained in the main component.

[0043] As the basic aqueous solution, at least one selected from the group consisting of alkali metal aluminates, hydroxides, carbonates, nitrites, silicates, and borates, as well as alkaline earth metal oxides and hydroxides, can be used. The type and amount of hydration initiator should be selected in accordance with the type and amount of blocking agent contained in the main agent.

[0044] The auxiliary agent in the epoxy resin composition according to this embodiment can be prepared by mixing the above-mentioned essential components with other components to be added as appropriate, as described later, and stirring thoroughly with, for example, a general rotary stirrer, so as not to cause unevenness in concentration.

[0045] The main and auxiliary components described above are available on the market either in their original form or with water or other components added, and can be easily obtained from the market. The epoxy resin composition according to this embodiment can be prepared by procuring each component individually, or by using commercially available compositions and adjusting the proportions of each component as appropriate.

[0046] [(3) Solvents] In the epoxy resin composition according to this embodiment, the three-component epoxy resin composition for surface preparation contains (3) a solvent as one of the three components, and this (3) solvent contains water as an essential component.

[0047] (3) There are no particular restrictions on the water used as a solvent; tap water, industrial water, river water, groundwater, deionized water, pure water, etc., can all be used. As long as the salt and sulfur content is not extremely high, it can be used without any problems, but of course, it is preferable to have fewer impurities. In addition to water as an essential component, the solvent in the three-component epoxy resin composition for surface preparation according to this embodiment may also contain other components as appropriate, as described later.

[0048] [Other ingredients] In addition to the essential components mentioned above, the epoxy resin composition according to this embodiment may optionally contain other components, specifically pigments, aggregates such as glass beads, crushed stone, and silica sand powder, anti-settling agents, diluents, surface modifiers, and various additives such as epoxy resin curing accelerators.

[0049] Since it is intended as a primer, it is generally not necessary for it to be colored, but if coloring is required, pigments may be added. Examples of pigments that can be added include pigments commonly used in paints, and are not particularly limited as long as they do not impede the stability of the epoxy resin composition. Examples include various coloring pigments, such as inorganic pigments such as titanium dioxide, lead yellow, iron oxide, and red iron oxide, and organic pigments such as azo pigments and phthalocyanine pigments, as well as extender pigments such as calcium carbonate, talc, alumina, mica, barite, and precipitated barium sulfate. In addition, aggregates such as glass beads, crushed stone, and silica sand powder can be used to increase film thickness and improve durability. The content of pigments and aggregates is not particularly limited, but it is preferable that it is in an amount that does not significantly affect the properties of the final coating film formed when used as a paint.

[0050] These other components may be included in one or two of the main agent, the auxiliary agent, and the solvent, or in all of them. Alternatively, an agent containing these other components may be prepared separately as an additive (which may be a liquid or a solid such as a powder).

[0051] [Composition ratio] In this embodiment, the epoxy resin composition is prepared to be usable as a coating solution by mixing the above-mentioned main component and auxiliary component in the case of a two-component type, the above-mentioned solvent in the case of a three-component type, and, if additives are prepared separately, all of the additives in a predetermined mixing ratio, and stirring thoroughly with, for example, a general rotary stirrer, to prevent unevenness in concentration.

[0052] The amount of each component in the epoxy resin composition according to this embodiment is determined so that the final coating solution has the appropriate blending ratio. Therefore, the amount of each component will change depending on the mixing ratio of the main component and the auxiliary component, or even the solvent. Furthermore, the preferred blending ratio of each component will differ between the two-component and three-component types. Accordingly, the blending ratios will be explained below, distinguishing between the two-component and three-component types.

[0053] In the context of a coating solution using a two-component epoxy resin composition for surface preparation, when referring to "when the main component and auxiliary component are mixed to prepare the coating solution" or "in the coating solution," it means that the main component and auxiliary component are mixed, and if there are separate additives, those additives are also mixed in to create the final "coating solution." Similarly, in the context of a coating solution using a three-component epoxy resin composition for surface preparation, when referring to "when the main component, auxiliary component, and solvent are mixed to prepare the coating solution" or "in the coating solution," it means that the main component, auxiliary component, and solvent are mixed, and if there are separate additives, those additives are also mixed in to create the final "coating solution." Hereinafter, the final coating solution using a two-component epoxy resin composition for surface preparation may simply be referred to as a "two-component coating solution," and the final coating solution using a three-component epoxy resin composition for surface preparation may simply be referred to as a "three-component coating solution."

[0054] In a two-component coating solution, the amount of epoxy resin and epoxy resin curing agent blended is preferably within the range of 10 to 70% by mass of the two-component coating solution, and more preferably within the range of 20 to 50% by mass. If the amount of epoxy resin and epoxy resin curing agent is too high, the amount of water that can be added becomes negligible, and it cannot be called a water-based paint. If the amount is too low, the water and alumina cement cannot be properly dispersed in the mixture of epoxy resin and epoxy resin curing agent, so both are undesirable. On the other hand, in a three-component coating solution, the amount of epoxy resin and epoxy resin curing agent blended is preferably within the range of 5 to 50% by mass of the three-component coating solution, and more preferably within the range of 12 to 35% by mass.

[0055] In this embodiment, the amount of epoxy resin curing agent to be blended varies depending on the type of epoxy resin curing agent used, the combination with the epoxy resin, and the desired paint or coating properties, so it is not possible to give a general answer. Generally, the amount of epoxy resin curing agent to be blended is such that the equivalent amount of the epoxy resin curing agent (or the amine equivalent if the epoxy resin curing agent is an amine) is approximately the same as the epoxy equivalent of the epoxy resin. However, depending on the desired coating properties, it is acceptable to have an excess amount of either the epoxy equivalent or the epoxy resin curing agent.

[0056] In a two-component coating solution, the amount of alumina cement is preferably in the range of 10 to 50% by mass of the two-component coating solution, and more preferably in the range of 20 to 40% by mass. Too much alumina cement prevents proper dispersion of water and alumina cement in the mixture of epoxy resin and epoxy resin hardener, while too little results in a negligible amount of water, making it unsuitable as a water-based paint. On the other hand, in a three-component coating solution, the amount of alumina cement is preferably in the range of 32 to 60% by mass of the three-component coating solution, and more preferably in the range of 15 to 30% by mass.

[0057] In this embodiment, the amount of basic aqueous solution added should be sufficient to neutralize the acid of the blocking agent contained in the main component, or an amount greater than that. When the pH at the alumina cement interface becomes 8 or higher due to neutralization, the hydration reaction of the alumina cement will resume. To obtain an appropriate hydration rate, it is preferable that the pH be 9 or higher, however, if the coating is to be applied to an alkaline substrate such as concrete, this may not be the case, taking into account the alkalinity of the substrate.

[0058] Furthermore, since the basic aqueous solution is added as an auxiliary agent, it is preferable that the concentration is such that it is completely soluble in the epoxy resin curing agent such as the amine used. More preferably, the basic aqueous solution has a pH of about 13 to 14 and is added as an auxiliary agent in an amount that maintains a pH that matches the curing rate of the resin mixture after mixing with the main agent. In other words, if the amount of basic aqueous solution added is too little, hydration will not be completed and the cured resin will remain water-containing, which may make it difficult to achieve proper resin performance. If it is too much, hydration will proceed prematurely, which may not only prevent the original pot life from being obtained but also lead to deterioration of the finished surface, both of which are undesirable. As described above, the appropriate amount of basic aqueous solution will vary depending on the type and amount of alumina cement, blocking agent, or epoxy resin curing agent, the substrate to be painted, etc.

[0059] In this embodiment, the water content in the two-component coating solution is preferably in the range of 5 to 30% by mass, and more preferably in the range of 10 to 20% by mass. If the amount of water is too much relative to the alumina cement, an excess amount of water will be generated that is not consumed in the hydration reaction, and this must be evaporated during the curing of the coating film. This reduces the effectiveness of the two-component epoxy resin composition for surface preparation according to this embodiment, which is less susceptible to the effects of humidity and temperature (described later) and less prone to film thickness reduction due to water evaporation. Furthermore, if the amount of water and dispersed alumina cement is too much, hydrates will be dispersed in the epoxy resin, which may result in the loss of the characteristics of the resulting cured product. On the other hand, if the amount of water is too little, it is not appropriate to call it water-based, and there is a concern that the viscosity of the coating solution will not decrease sufficiently, leading to reduced paintability, which is undesirable.

[0060] In this embodiment, the content of the curing product forming component in the two-component coating solution is preferably 85 to 100% by mass, more preferably in the range of 95 to 100% by mass, and particularly preferably close to 100% by mass. Furthermore, the content of the curing product forming component in the three-component coating solution is preferably 50 to 75% by mass, and more preferably in the range of 60 to 70% by mass.

[0061] In this context, "hardened product-forming components" refers to all components of the coating solution that harden through the curing reaction of epoxy resin and all components that harden through the hydration reaction of alumina cement. Regarding water, the amount consumed by the hydration reaction of alumina cement and hardened is considered a hardened product-forming component, while excess water not used in the hydration reaction is not considered a hardened product-forming component. Experimentally, the amount of water hydrated by alumina cement is affected by the concentration and amount of the basic aqueous solution used to release the blockage, as well as the extender pigments used in combination. However, based on empirical observation, it is estimated that approximately 90% of the mass of the blended alumina cement is fixed within the coating film through hydration (i.e., it corresponds to the hardened product-forming component).

[0062] In this embodiment, some or all of the water in the coating solution, which contributes to the coating suitability, is subjected to the hydration reaction of the alumina cement and thus becomes a hardened product forming component. Therefore, the content of the hardened product forming component in the coating solution can be made to 100% by mass or close to 100% by mass, thereby suppressing the reduction in film thickness due to the volatilization of the solvent.

[0063] The content of curing agent-forming components in the coating solution can be determined by preparing a cured body and measuring the weight change. In this embodiment, as an example, the content of curing agent-forming components was determined by the following method.

[0064] A mold with a depth of 4 mm and a diameter of 65 mm, designed to easily remove the cured material (for example, a polypropylene mold), was prepared. The mass a (g) required to produce a 4 mm thick material was calculated from the specific gravity of the mixture, and the mixture of this mass a was poured into the mold to produce a cured material. At this time, since the amount of reduction will be calculated later as a percentage, an accuracy of ±5% in the poured mass is sufficient. The mixture was then kept in a constant environment, and after a predetermined time had elapsed, the mass b (g) was measured. From this measured value and the mass a poured into the mold, the content S (%) of the cured material forming component was calculated using the following formula (1). S = b / a × 100 ... (1)

[0065] [Painting with epoxy resin composition] The epoxy resin composition according to this embodiment is used in the painting operation in the form of a two-component or three-component coating solution (hereinafter, these may be collectively referred to simply as "coating solution") prepared as described above. For the application method of the coating solution, painting tools suitable for the application thickness and the object to be coated, such as trowels, spatulas, brushes, rollers, and applicators, may be used, or known methods such as spray application using a resin gun or multi-purpose gun may be used.

[0066] [Coating film formation mechanism] Figure 1 shows a schematic diagram illustrating the state of the main component and auxiliary component (separate component) in the epoxy resin composition according to this embodiment. Although the solvent in the three-component coating solution is omitted in Figure 1, the excess water that would result from the presence of an additional solvent does not contribute to the reaction shown in Figure 1 and evaporates separately from this reaction, thus leaving the three-component coating solution.

[0067] As shown in Figure 1, the main component is a w / o emulsion in which the epoxy resin exhibits hydrophobicity (o) and water droplets (w) are dispersed within it. The water droplets contain alumina cement whose hydration reaction is blocked by a blocking agent. The auxiliary component contains an epoxy resin hardener and a basic aqueous solution, forming an aqueous liquid.

[0068] When the main component and auxiliary component are mixed and thoroughly stirred, first, as shown by arrow a in Figure 1, the epoxy resin curing agent in the auxiliary component reacts with the epoxy resin in the main component, and the epoxy resin curing reaction proceeds. At the same time, as shown by arrow b in Figure 1, the blocking agent in the main component reacts with the basic aqueous solution of the auxiliary component, neutralizing the blocking agent. Then, the blocking of the hydration reaction by the blocking agent is released, and as shown by arrow c1 in Figure 1, the hydration reaction between the alumina cement in the main component and the water begins. Furthermore, as shown by arrow c2 in Figure 1, the alumina cement in the main component also undergoes a hydration reaction with the water contained in the auxiliary component.

[0069] The coating solution, prepared by mixing the main component and auxiliary component, is in a state where the curing reaction of the epoxy resin and the hydration reaction of the alumina cement proceed simultaneously. Before these reactions proceed, the coating solution is subjected to the painting operation. The coating film thus formed is created when these two reactions proceed.

[0070] Figure 2 shows a schematic diagram illustrating the state of a coating film formed by a coating solution prepared using the epoxy resin composition according to this embodiment (hereinafter sometimes abbreviated as "coating film formed by this embodiment"). As shown in Figure 2, the coating film formed by this embodiment has a state in which hardened alumina cement hydrate is dispersed within the curing product of the epoxy resin and epoxy resin curing agent. In addition, a small amount of neutralized product of the blocking agent and the base in the basic aqueous solution remains within the alumina cement hydrate. Since this neutralized product is present in a very small amount and is neutral or weakly alkaline, it has almost no effect on the alumina cement hydrate or the hardened epoxy resin.

[0071] As described above, the coating film formed by this embodiment does not involve the evaporation of water in the curing reaction, and the curing reaction proceeds within the coating film. Therefore, it is less susceptible to the effects of humidity and temperature, and film thickness reduction due to water evaporation is less likely to occur. Consequently, the coating film formed by this embodiment significantly reduces problems that commonly occur with water-based paints, such as poor drying under high humidity conditions, delayed curing at low temperatures, and film thickness reduction due to water evaporation.

[0072] While water-based epoxy resin paints inevitably suffer from poor water resistance, the main component of the epoxy resin composition according to this embodiment is composed of water-insoluble raw materials. The curing agent is mixed with the main component, and as the hydration of the alumina cement and neutralization of the alkali proceed, the water-soluble amines become hydrophobic. Furthermore, curing through reaction with the epoxy resin results in virtually no decrease in the water resistance of the resulting coating film. The epoxy resin composition according to this embodiment inherits the performance of cured products made from oil-based liquid epoxy resin paints whose viscosity is adjusted with organic solvents, while enabling viscosity adjustment with water instead of organic solvents, and significantly suppressing volume reduction after curing due to evaporation. Therefore, the coating liquid according to this embodiment has low viscosity, and after curing of the coating film made with this coating liquid, it becomes high in solids.

[0073] In the three-component coating solution, the evaporation of excess water appears to be no different from conventional water-based paints, but after a certain amount of water has evaporated, the above-described state is achieved, resulting in properties similar to those of a two-component coating solution. In other words, without creating an unnecessarily thick film, a sufficient film thickness is achieved as a primer, and the surface is strengthened by the concrete-impregnation properties of the liquid epoxy resin, which are not found in general water-based paints, for absorbent substrates such as concrete, resulting in good adhesion.

[0074] The coating film formed by this embodiment primarily exhibits the properties of a cured epoxy resin. Furthermore, since alumina cement hydrate is dispersed within the cured epoxy resin, and the alumina cement hydrate functions as a filler, a coating film with excellent mechanical strength (e.g., abrasion resistance) can be expected.

[0075] The epoxy resin composition according to this embodiment is a water-based agent that does not contain organic solvents in either the main component or the auxiliary component, so there is no concern about being subject to various regulations under the Fire Service Act, and it is easy to handle.

[0076] <Applications to other uses> Due to its unique curing mechanism and properties, the two-component epoxy resin composition for surface preparation according to this embodiment can be applied to uses other than paints, such as those listed below.

[0077] (Resin mortar material or paste material) By further adding coarse aggregate to the two-component epoxy resin composition for surface preparation according to this embodiment, it can be used as a resin mortar or paste material. In this case, it is preferable to mix the main component and auxiliary component to prepare a mixed solution and then add the coarse aggregate. The resin mortar or paste material obtained in this way is excellent as a resin mortar or paste material in that it has the property of having little volume reduction during curing.

[0078] The coarse aggregate used when incorporating the resin mortar material or paste material may be included in either the main component or the auxiliary component, or in both, or in a separately prepared additive, similar to the "other components" described above.

[0079] The amount of coarse aggregate to be added depends on the required thickness and the particle size of the aggregate used. For example, for a surface preparation material with a thickness of about 0.5 to 1 mm intended for roughening concrete surfaces or backfilling voids, it is appropriate to use No. 8 silica sand or aggregate of a similar particle size, in an amount of about 1x by mass relative to the total amount of the main and auxiliary components of the epoxy resin composition according to this embodiment. If the target thickness is about 5 mm, it is appropriate to use No. 5 silica sand or aggregate of a similar particle size, in an amount of about 4x by mass relative to the total amount of the main and auxiliary components of the two-component epoxy resin composition for surface preparation according to this embodiment. If the target thickness is about 10 mm, it is appropriate to use No. 4 silica sand aggregate, in an amount of about 5x by mass. Naturally, the amount of aggregate to be added may be adjusted or aggregates of different particle sizes may be used in combination depending on the properties expected from the resin mortar or paste material, such as ease of handling, surface finish, and adhesion to the substrate. [Examples]

[0080] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

[0081] (Example 1: Example of paint application) Example 1 is an example of a roller-applied primer for concrete floors using the three-component epoxy resin composition for surface preparation according to this embodiment.

[0082] <Preparation of the coating solution in Example 1> (1) Preparation of the main ingredient As the epoxy resin, we used Beccopox EP-147W (a bisphenol A type liquid epoxy resin manufactured by Daicel Ornex Co., Ltd., with a solid content of 100% and epoxy equivalent of 195), which is a self-emulsifying epoxy resin. In addition, Exalt (manufactured by Imerys) was used as the alumina cement. Exalt is a water-dispersed product in which the hydration reaction is blocked.

[0083] ERISYS AED-16L (Huntsman Advanced Materials, 1,6-hexanediol glycidyl ether) was added as a diluent, alumina CA5M (DAEJOO-KC) as a solids content adjuster, and Floren AC-326F (Kyoeisha Chemical Co., Ltd., vinyl ether polymer) as a surface modifier (antifoamer). Furthermore, Disparon AQR562 (Kusumoto Chemical Co., Ltd.) and BYK3450 (BIC Chemie Japan) were added as surface modifiers when diluting with water. The composition of the main ingredient is as shown in Table 1 below (units in the table are parts by mass). Table 1 also includes the composition of the auxiliary ingredients, which will be discussed later.

[0084] [Table 1]

[0085] From the formulations shown in Table 1 above, epoxy resin, diluent, and Floren AC-326F (total amount 50.2) were mixed, and separately, a mixture of alumina cement, alumina, AQR562, and BYK3450 (total amount 43.5) was added and homogenized to prepare the main component of Example 1.

[0086] (2) Preparation of adjuvants As an epoxy resin curing agent, 22.5 parts by mass of Fujicure 8167-D (manufactured by T&K TOKA Corporation, modified amine-based curing agent, amine value: 395-435, standard compounding equivalent: 85 g / eq) was mixed with 3 parts by mass of a 2% by mass sodium hydroxide aqueous solution to prepare the auxiliary agent for Example 1.

[0087] (3) Preparation of the coating solution The main component and auxiliary component obtained as described above were mixed in a mixing ratio of main component:auxiliary component = 7:2, and thoroughly stirred using a propeller-type stirrer until homogeneous. Then, 50 parts by mass of water as a solvent were added to 100 parts by mass of the mixture to prepare the three-component coating solution of Example 1.

[0088] (4) Painting and evaluation tests On the surface of a concrete slab (30cm x 30cm x 6cm) specified in JIS A 5371 "Precast Unreinforced Concrete Products," which had been thoroughly treated to remove laitance by sanding with #40 grit sandpaper, the three-component coating liquid of Example 1 was applied as a primer using a roller at a rate of 0.12 kg / m². 2 The mixture was applied in this manner. This was done under conditions of 5°C and 80% RH humidity.

[0089] After confirming that the surface had hardened to the point where it could be top-coated after 6 hours in the same environment, a solvent-free epoxy paint (product name: Floor Top #8000, manufactured by Atomix Co., Ltd.) was applied using a spatula according to the product's painting specifications (intermediate coat 0.3 kg / m²). 2 After 16 hours, apply a top coat of 0.8 kg / m². 2 The solution was applied according to the instructions and left to stand for 20 hours. The entire process, from application to standing, was carried out under the same conditions (temperature 5°C, humidity 80%RH).

[0090] Upon inspection of the hardened painted surface, a smooth surface was found to be free of dents and pinholes caused by the underlying material.

[0091] Furthermore, the adhesion between the topcoat and the substrate, as well as the adhesion strength of the composition of Example 1 as a primer, was evaluated in accordance with the Floor Coating Adhesion Strength Test Method NNK-005 (2020) (established by the Technical Committee of the Japan Floor Coating Industry Association). Note that the Floor Coating Adhesion Strength Test Method NNK-005 is basically the same as the test method specified in JIS K5600-5-7 (Mechanical Properties of Coating Films: Adhesion (Pull-off Method)) (whereas JIS uses a cylindrical jig, a square jig is used). However, the square jig was attached to the surface of a coating film made of solvent-free epoxy paint (product name: Floor Top #8000, manufactured by Atomix Co., Ltd.) with an epoxy resin adhesive (product name: Bond Quick Mender, manufactured by Konishi Co., Ltd.). The test was performed five times, and the fracture surface and adhesion strength were calculated. All test results were cohesive failure of the test substrate, and the adhesion strength (unit: N / mm) was calculated. 2 The average score was 4.80 (minimum 4.53, maximum 5.01), confirming that it possesses high performance as a primer.

[0092] (Example 2: Example as an intermediate coating material) Example 2 is an example in which the intermediate coating step of the solvent-free epoxy paint in Example 1 is replaced with a mixture of a main component and an auxiliary component (two-component coating solution) without the addition of a solvent.

[0093] The main component and auxiliary component of Example 1 were mixed in a ratio of main component:auxiliary component = 7:2. Without adding any solvent, the mixture was thoroughly stirred using a propeller-type stirrer to prepare a coating solution. The specific gravity of the obtained coating solution was 1.33.

[0094] a) Measurement of coating thickness To measure the thickness of the coating, 11g of the material was smoothly applied to a 7cm x 15cm glass plate using a spatula. The plate was then cured at 23°C and 50% humidity for 48 hours to allow it to fully harden. The formed coating was then peeled off the glass plate, its cross-section was cut out with a cutter, and the exposed cross-section was photographed with an optical microscope (100x magnification). Figure 3 shows the optical microscope image of the coating cross-section. In the image in Figure 3, the central layer is the cross-section of the coating, and the lower surface is the surface that was attached to the glass plate. In the image in Figure 3, there is empty space above and below the coating. The film thickness measured from the cross-section of the coating in the photograph was approximately 0.79mm, which was in close agreement with the theoretical value.

[0095] b) Hardness and thickness reduction of the coating film (cured film) 17.8 g of the coating solution from Example 1 (a mass resulting in a thickness of 4 mm calculated from its specific gravity) was poured into a polypropylene mold with a diameter of 65 mm and a depth of 4 mm under conditions of 5°C and 80% RH humidity, and left to stand for 48 hours under the same conditions. The mass of the resulting cured film was measured to be 17.6 g (mass loss of 1.1%). The durometer hardness of this cured film (Type D durometer hardness according to JIS K7215; the same applies hereafter) was HDD63, which was sufficient hardness for a coating film.

[0096] The samples, which had been left to stand under the above conditions, were further left to stand (cured) for 24 hours in an environment of 40°C and 30% RH humidity. The mass of the cured film after standing (curing) was measured, and the average was 17.2 g (mass decrease of 3.4%). The durometer hardness of this cured film (Type D durometer hardness according to JIS K7215; the same applies below) was HDD68, which was sufficiently hard as a coating film. This confirmed that almost all of the coating liquid constituted the cured film.

[0097] On the surface of a concrete slab (30cm x 30cm x 6cm) specified in JIS A 5371 "Precast Unreinforced Concrete Products," which had been thoroughly treated to remove laitance by sanding with #40 grit sandpaper, the composition of Example 2 was applied as a primer using a roller at a rate of 0.12 kg / m². 2was applied so as to achieve the target state. This operation was performed in an environment with a temperature of 5°C and a humidity of 80%RH.

[0098] After confirming that curing proceeded to a degree that allowed topcoating 6 hours after application under the same environment, the coating liquid of Example 2 was applied at 0.3 kg / m using a spatula 2 , and after 16 hours, a solvent-free epoxy paint (trade name: Floor Top #8000, manufactured by Atomics Co., Ltd.) was applied in accordance with the coating specifications of this product (topcoat 0.8 kg / m 2 ), followed by standing for 48 hours. All operations from application to standing were performed under the same environment (temperature 5°C, humidity 80%RH).

[0099] When the cured coated surface was observed, a smooth coated surface free of dents and pinholes caused by the underlying layer was obtained.

[0100] In addition, the adhesion between the interlayer with the topcoat material and the primer was evaluated for the adhesive strength of the composition of Example 2 as an intermediate coat, in accordance with the floor coating adhesion strength test method NNK-005 (2020) (established by the Technical Committee of Japan Floor Coating Industry Association). The floor coating adhesion strength test method NNK-005 is basically the same as the test method specified in JIS K5600-5-7 (Mechanical properties of coating films - Adhesion (Pull-off method)) (the JIS standard uses a cylindrical jig, while a square jig is used here). However, the square jig was bonded to the surface of the coating film formed by the solvent-free epoxy paint (trade name: Floor Top #8000, manufactured by Atomics Co., Ltd.) using an epoxy resin adhesive (trade name "Bond Quick Mender", manufactured by Konishi Co., Ltd.). The test was performed 5 times to calculate the fracture surface and adhesion strength. All test results showed cohesive failure of the test substrate, and the adhesion strength (unit: N / mm 2 ) was an average of 4.86 (minimum 4.82, maximum 4.88), confirming that it has performance equivalent to that of a solvent-free epoxy paint as an intermediate coat.

[0101] (Example 3: Example for putty material application) To the coating solution of Example 2, 15% by mass of Milcon MS-2 (manufactured by Showa KDE Co., Ltd.), a thickening agent for sepiolite, was added externally and thoroughly stirred. The mixture was well-mixed, and the composition of Example 3, which can be used as an adhesive or putty material with good handling properties, was obtained.

[0102] <Evaluation test as a putty material> On the surface of a concrete slab (30cm x 30cm x 6cm) specified in JIS A 5371 "Precast Unreinforced Concrete Products," which had been thoroughly treated to remove laitance by sanding with #40 grit sandpaper, the composition of Example 3 was applied as a primer using a roller at a rate of 0.12 kg / m². 2 The mixture was applied in this manner. This was done under conditions of 5°C and 80% RH humidity.

[0103] After confirming that the coating solution from Example 3 had hardened to the point where it could be applied over another coat after 6 hours in the same environment, a spatula was used to apply 2 kg / m² of the coating solution from Example 3. 2 Apply the coating, and after 16 hours, apply solvent-free epoxy paint (product name: Floor Top #8000, manufactured by Atomix Co., Ltd.) according to the product's painting specifications (topcoat 0.8 kg / m²). 2 The solution was applied according to the instructions and left to stand for 20 hours. The entire process, from application to standing, was carried out under the same conditions (temperature 5°C, humidity 80%RH).

[0104] Upon inspection of the hardened painted surface, a smooth surface was found to be free of dents and pinholes caused by the underlying material.

[0105] Furthermore, the adhesion between layers was evaluated using the composition of Example 3 as a putty material, in accordance with the NNK-005 (2020) test method for floor coating adhesion strength (established by the Technical Committee of the Japan Floor Coating Industry Association). Note that the NNK-005 test method for floor coating adhesion strength is basically the same as the test method specified in JIS K5600-5-7 (Mechanical properties of coating films: adhesion (pull-off method)) (however, a square jig is used, whereas a cylindrical jig is used in JIS). However, the square jig was attached to the surface of a coating film made of solvent-free epoxy paint (product name: Floor Top #8000, manufactured by Atomix Co., Ltd.) using an epoxy resin adhesive (product name: Bond Quick Mender, manufactured by Konishi Co., Ltd.). The test was performed five times, and the fracture surface and adhesion strength were calculated. All test results showed cohesive failure of the test substrate, and the adhesion strength (unit: N / mm²) was calculated. 2 The average score was 4.45 (minimum 3.91, maximum 5.21), confirming that it possesses high performance as a putty material.

[0106] (Example 4: Example of paste material application) 100 parts by mass of silica sand No. 8 was added to 100 parts by mass of the coating solution of Example 2 and thoroughly stirred. The mixing properties were good, and the composition of Example 4, which can be used as a wiping material, was obtained.

[0107] <Evaluation test as a cutting material> On the surface of a concrete slab (30cm x 30cm x 6cm) specified in JIS A 5371 "Precast Unreinforced Concrete Products," which had been thoroughly treated to remove laitance by sanding with #40 grit sandpaper, the composition of Example 4 was applied as a finishing material using a spatula at a rate of 0.8 kg / m². 2 The mixture was applied in this manner. This was done under conditions of 5°C and 80% RH humidity.

[0108] After confirming that the surface had hardened enough to be applied over a topcoat after 16 hours in the same environment, a solvent-free epoxy paint (product name: Floor Top #8000, manufactured by Atomix Co., Ltd.) was applied according to the product's painting specifications (topcoat 0.8 kg / m²). 2The solution was applied according to the instructions and left to stand for 48 hours. The entire process, from application to standing, was carried out under the same environmental conditions (temperature 5°C, humidity 80%RH).

[0109] Upon inspection of the hardened painted surface, a smooth surface was found to be free of dents and pinholes caused by the underlying material.

[0110] Furthermore, the adhesion between the topcoat and the substrate was evaluated in accordance with the NNK-005 (2020) method for testing the adhesion strength of floor coatings (established by the Technical Committee of the Japan Floor Coating Industry Association), using the composition of Example 4 as a scrubbing material. Note that the NNK-005 method for testing the adhesion strength of floor coatings is basically the same as the test method specified in JIS K5600-5-7 (Mechanical properties of coating films: adhesion (pull-off method)) (however, a square jig is used instead of the cylindrical jig used in JIS). However, the square jig was attached to the surface of a coating film made of solvent-free epoxy paint (product name: Floor Top #8000, manufactured by Atomix Co., Ltd.) using an epoxy resin adhesive (product name: Bond Quick Mender, manufactured by Konishi Co., Ltd.). The test was performed five times, and the fracture surface and adhesion strength were calculated. All test results showed cohesive failure of the test substrate, and the adhesion strength (unit: N / mm²) was calculated. 2 The average score was 5.75 (minimum 4.95, maximum 6.64), confirming that it possesses high performance as a cutting material. [Industrial applicability]

[0111] As described above, the two-component epoxy resin composition for surface preparation of the present invention was developed for paint applications and is therefore preferably used as a paint. However, it can also be used as a resin mortar or paste by adding coarse aggregate, or as a putty or adhesive by adding a thickener. When applied to these uses other than paint, it is of course included in the implementation of the two-component epoxy resin composition for surface preparation of the present invention.

Claims

1. A main component comprising at least a water-dispersible epoxy resin, water, and alumina cement in which the hydration reaction is blocked, An epoxy resin curing agent for curing the epoxy resin, and an auxiliary agent comprising a basic aqueous solution for releasing the blockage of the hydration reaction of the alumina cement, A two-component epoxy resin composition for surface preparation.

2. The two-component epoxy resin composition for surface preparation according to claim 1, wherein the coating solution prepared by mixing the main agent and the auxiliary agent contains 5 to 30% by mass of water and 85 to 100% by mass of curing material forming components.

3. The two-component epoxy resin composition for surface preparation according to claim 1, wherein the epoxy resin is a self-emulsifying liquid epoxy resin.

4. The two-component epoxy resin composition for surface preparation according to claim 1, wherein the epoxy resin curing agent is a polyamine.

5. The two-component epoxy resin composition for surface preparation according to claim 1, further comprising coarse aggregate, and used as a resin paste or resin mortar.

6. A main component comprising at least a water-dispersible epoxy resin, water, and alumina cement in which the hydration reaction is blocked, An epoxy resin curing agent for curing the epoxy resin, and an auxiliary agent comprising a basic aqueous solution for releasing the blockage of the hydration reaction of the alumina cement, A solvent containing water, A three-component epoxy resin composition for surface preparation.

7. The three-component epoxy resin composition for surface preparation according to claim 6, wherein the coating solution prepared by mixing the main agent, the auxiliary agent, and the solvent has a water content of 32 to 60% by mass and a curing product forming component content of 50 to 70% by mass.

8. The three-component epoxy resin composition for surface preparation according to claim 6, wherein the epoxy resin is a self-emulsifying liquid epoxy resin.

9. The three-component epoxy resin composition for surface preparation according to claim 6, wherein the epoxy resin curing agent is a polyamine.

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