JP2020094083A - Resin composition, curing failure prediction method, method for manufacturing joined body, adhesive kit, and curing failure detection device - Google Patents

Abstract

To provide a resin composition which can easily suppress occurrence of curing failure, a curing failure prediction method, a method for manufacturing a joined body, an adhesive kit, and a curing failure detection device.SOLUTION: A resin composition contains a synthetic resin cured by ring-opening polymerization, and a pH indicator changing optical characteristics according to pH.SELECTED DRAWING: Figure 4

Description

The present technology relates to a resin composition applied to adhesion of members, a method for predicting curing failure, a method for manufacturing a bonded body, an adhesive kit, and a curing failure detection device.

Conventionally, a synthetic resin in which a curing reaction proceeds by ring-opening and polymerization of a ring structure is known. For example, epoxy resins, benzooxy resins, and imide resins are synthetic resins that cure by ring-opening polymerization and are widely used as base materials for adhesives and fiber-reinforced composites (FRPs). Has been done. In these synthetic resins, the cyclic compound may be consumed due to, for example, the attachment of sweat or exhaled air of the worker to cause defective curing. Such a curing failure may cause, for example, adhesion failure or strength reduction.

As a method for detecting the curing failure of the synthetic resin, for example, a nondestructive inspection using ultrasonic waves is known. Further, Patent Document 1 describes a method of arranging a magnetic material having a stress-magnetic characteristic in an adhesive layer to detect adhesion failure. In this method, for example, an adhesive sheet in which an adhesive such as a thermosetting epoxy resin is impregnated in a magnetic material is used. When the adhesive sheet is subjected to a hardening treatment such as heating, the magnetic permeability and the like of the magnetic material change due to hardening and expansion and contraction of the adhesive. For example, it is possible to detect adhesion failure by measuring magnetic permeability using a magnetic sensor or the like (see paragraphs [0019], [0022], [0026], [0030] in FIG. 4 etc.).

JP, 6-155583, A

In the nondestructive inspection using ultrasonic waves or the like or the method described in Patent Document 1, after the adhesive is cured and the object is adhered, the goodness/badness of the adhesion is determined. Therefore, when a defect is determined, it is necessary to discard the members, redo the bonding, or the like, which may cause a time loss and an increase in manufacturing cost. In addition, the use of dedicated equipment may increase the cost and labor for detecting defective curing. Therefore, there is a demand for a technique capable of easily suppressing the occurrence of curing failure.

In view of the above circumstances, an object of the present invention is to provide a resin composition capable of easily suppressing the occurrence of curing failure, a method of predicting curing failure, a method for manufacturing a bonded body, an adhesive kit, and a curing failure detection device. To provide.

In order to achieve the above object, the resin composition according to one embodiment of the present invention contains a synthetic resin that cures by ring-opening polymerization and a pH indicator whose optical properties change according to pH.

This resin composition contains a synthetic resin that cures by ring-opening polymerization and a pH indicator that changes optical properties. The synthetic resin includes a ring structure that causes ring-opening polymerization. For example, when salt contained in sweat, exhaled breath, or the like adheres to the synthetic resin, the ring structure is consumed and the pH of the adhesion site changes. By detecting the optical characteristics of the pH indicator according to this change in pH, it is possible to detect a location where curing failure is predicted. As a result, it becomes possible to easily suppress the occurrence of curing failure.

The synthetic resin may be an adhesive or a base material of a fiber-reinforced composite material.
This makes it possible to sufficiently avoid the occurrence of curing failure or the like in the adhesive or the fiber-reinforced composite material.

The pH indicator may be a fluorescent indicator whose fluorescence changes according to the pH.
By using a fluorescence indicator, for example, the color and intensity of fluorescence change according to pH, so that it is possible to easily detect alteration of the resin composition by fluorescence observation and the like.

The pH indicator may be a color change indicator that changes color depending on the pH.
By using the color change indicator, for example, the color of the resin composition itself mixed with the color change indicator changes according to the pH, so that alteration of the resin composition or the like can be easily detected.

The synthetic resin may be at least one of an epoxy resin, a benzooxy resin, or an imide resin.
By using an epoxy resin, it is possible to provide a highly versatile resin material or the like. Further, by using a benzooxy-based resin, it is possible to provide a resin material or the like that has less heat shrinkage during curing, for example. Further, by using the imide-based resin, for example, it is possible to provide a resin material having excellent heat resistance.

A method for predicting curing failure according to one aspect of the present invention provides a bonding layer, which is composed of a resin composition containing a synthetic resin that cures by ring-opening polymerization and a pH indicator whose optical properties change according to pH, on a bonding target. ..
In the uncured state of the resin composition, the optical characteristics of the bonding layer are observed to detect an altered portion of the bonding layer.

In this method of predicting poor curing, the bonding layer is formed using a resin composition in which a synthetic resin that cures by ring-opening polymerization and a pH indicator are mixed. Further, in the uncured state of the resin composition, the altered portion of the bonding layer is detected from the optical characteristics of the pH indicator. As a result, it becomes possible to detect the deteriorated portion where the curing failure is predicted before the resin composition is cured, and it is possible to easily suppress the occurrence of the curing failure.

The synthetic resin may be an adhesive. In this case, the bonding layer may be an adhesive layer formed on the bonding object.
This makes it possible to avoid the occurrence of poor curing or poor adhesion of the adhesive in advance.

The synthetic resin may be a base material of a fiber-reinforced composite material. In this case, the bonding layer may be a laminated member that is the fiber-reinforced composite material.
As a result, it becomes possible to avoid in advance the occurrence of defective curing or reduction in strength of the fiber-reinforced composite material.

The pH indicator may be a fluorescent indicator whose fluorescence changes according to the pH. In this case, in the step of observing the optical characteristic, the bonding layer may be irradiated with predetermined excitation light to observe the fluorescence of the fluorescent indicator.
For example, changes in the color and intensity of fluorescence depending on pH are observed. By using this observation result, it is possible to easily detect alteration and the like of the resin composition.

The pH indicator may be a color change indicator that changes color depending on the pH. In this case, the color of the bonding layer may be observed in the step of observing the optical property.
For example, a change in color of the resin composition itself depending on pH is observed. By using this observation result, it is possible to easily detect alteration and the like of the resin composition.

The synthetic resin may be at least one of an epoxy resin, a benzooxy resin, or an imide resin.
This makes it possible to avoid in advance curing defects such as epoxy resin, benzooxy resin, and imide resin.

A method for producing a joined body according to an aspect of the present invention comprises a joining layer made of a resin composition containing a synthetic resin which is cured by ring-opening polymerization and a pH indicator whose optical properties change depending on pH. Set up.
In the uncured state of the resin composition, the optical characteristics of the bonding layer are observed to detect an altered portion of the bonding layer.
The resin composition in the altered portion detected is replaced with a new resin composition.
Objects to be joined are joined to the joining layer to form a joined body.

In this method for producing a joined body, the joining layer is formed using a resin composition in which a synthetic resin that is cured by ring-opening polymerization and a pH indicator are mixed. Further, in the uncured state of the resin composition, the altered portion of the bonding layer is detected from the optical characteristics of the pH indicator. The resin composition of the altered portion is replaced with a new resin composition to form a joined body of the object to be joined and the object to be joined. This makes it possible to provide a highly reliable bonded body in which curing failure, adhesion failure, etc. are sufficiently suppressed.

An adhesive kit according to an aspect of the present invention has a main agent containing a synthetic resin that cures by ring-opening polymerization, and a curing agent that cures the synthetic resin, and at least one of the main agent and the curing agent is adjusted to pH. A pH indicator whose optical properties change accordingly is mixed.

A curing failure detection device according to an aspect of the present invention includes an observation unit and a detection unit.
The observing section observes the optical characteristics of a bonding layer made of a resin composition containing a synthetic resin which is cured by ring-opening polymerization and a pH indicator whose optical characteristics change according to pH.
The detection unit detects an altered portion of the bonding layer based on the observation result of the optical characteristics.

As described above, according to the present invention, it is possible to easily suppress the occurrence of defective curing. Note that the effects described here are not necessarily limited, and may be any effects described in the present disclosure.

It is a schematic diagram which shows the structural example of the adhesive agent containing the resin composition which concerns on 1st Embodiment. It is a schematic diagram for explaining an example of a ring-opening polymerization reaction. It is a figure which shows the chemical structure of fluorescein which is an example of a pH indicator. It is a flowchart which shows an example of the curing failure prediction method using a mixed adhesive. It is a schematic diagram which shows an example of the adhesive layer containing a mixed adhesive agent. It is a figure for demonstrating an example of the chemical reaction in an alteration part. It is a schematic diagram which shows an example of the process of detecting an altered part. It is a flowchart which shows an example of the manufacturing method of the joined body using a mixed adhesive agent. It is a schematic diagram which shows an example of the manufacturing process of the joined body using a mixed adhesive agent. It is a schematic diagram which shows the structural example of the laminated member and laminated body which concern on 2nd Embodiment. It is a flow chart which shows an example of a manufacturing method of a layered product using a layered member. It is a schematic diagram which shows an example of the process of detecting an altered part. It is a schematic diagram which shows an example of the adhesive kit which concerns on other embodiment. It is a schematic diagram which shows an example of the curing failure detection apparatus which concerns on other embodiment.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic diagram showing a configuration example of an adhesive containing the resin composition according to the first embodiment. The resin composition 10 contains a synthetic resin 11 which is cured by ring-opening polymerization and a pH indicator 12 whose optical characteristics change according to pH. That is, it can be said that the resin composition 10 is the synthetic resin 11 in which the pH indicator 12 is mixed, and is a mixture (resin mixture) of the synthetic resin 11 and the pH indicator 12.

In this embodiment, the synthetic resin 11 is an adhesive. Therefore, the resin composition 10 functions as an adhesive for bonding various members. Below, the adhesive in which the pH indicator 12 is mixed is referred to as the mixed adhesive 20. An adhesive (synthetic resin 11) in which the pH indicator 12 is not mixed is referred to as an unmixed adhesive 21.

The mixed adhesive 20 according to the present embodiment can be used in various fields such as manufacturing industry, maintenance, repair, and overhaul where the adhesive is used. Further, the mixed adhesive 20 can be used in various fields such as automobiles, ships, aerospace, and construction.

In the example shown in FIG. 1, a state in which a paste-like unmixed adhesive 21 and a solid pH indicator 12 are kneaded to produce a mixed adhesive 20 is schematically illustrated. The present invention is not limited to this, and for example, a liquid unmixed adhesive 21 may be used. Further, the pH indicator 12 may be kneaded in a state of being dispersed in a predetermined solvent.

The unmixed adhesive 21 (synthetic resin 11) is an adhesive of the type that is cured by ring-opening polymerization as described above, and includes a prepolymer having a ring structure that opens during a polymerization reaction. The unmixed adhesive 21 is the uncured synthetic resin 11, and the curing reaction proceeds by the polymerization of the prepolymer. In the present disclosure, a semi-cured state in which the prepolymer is partially polymerized, that is, a state in which the synthetic resin 11 is not sufficiently cured is included in the uncured state.

As the unmixed adhesive 21, for example, an adhesive containing an epoxy resin, a benzooxy resin, an imide resin, or the like (epoxy adhesive, benzooxy adhesive, imide adhesive, etc.) can be used. is there. Each adhesive is typically used alone, but the present technology can be applied even when mixed.

The epoxy adhesive is an adhesive containing a prepolymer having an epoxy ring (also referred to as an epoxide or an epoxy group), and the properties such as adhesive strength, adhesive time, heat resistance, and viscosity can be easily adjusted. The benzooxy adhesive is an adhesive containing a prepolymer having a benzooxy ring (also referred to as benzoxazine), and is, for example, an adhesive having a small curing shrinkage and excellent in shape stability after adhesion. The imide-based adhesive is an adhesive containing a prepolymer having a cyclic imide structure (also referred to as an imide ring), and can generally exhibit high heat resistance. As the epoxy adhesive, benzooxy adhesive, and imide adhesive, commercially available products can be used. The specific configuration of the prepolymer contained in each adhesive is not limited.

FIG. 2 is a schematic diagram for explaining an example of the ring-opening polymerization reaction. FIG. 2 schematically shows the ring-opening polymerization reaction of the epoxy ring. Hereinafter, the curing of the resin by ring-opening polymerization will be described with reference to FIG. 2 by taking an epoxy ring as an example.

(Chemical formula 1) is an example of a prepolymer of an epoxy adhesive. The prepolymer shown in (Chemical Formula 1) is a linear epoxy and has epoxy rings on both ends of the main chain. In addition, for example, novolac type epoxy having epoxy rings at the ends of a plurality of side chains may be used. Further, for example, a prepolymer having another structure such as an aliphatic epoxy or an aliphatic cyclic epoxy may be used.

The drawings on the left and right sides of FIG. 2A are schematic views showing an epoxy ring in a closed state and an epoxy ring in an opened state. The epoxy ring has a three-membered ring structure in which two carbons C and one oxygen O are cyclically bonded. This ring structure is a moderately unstable structure and opens when heated or the like. For example, as shown on the right side of FIG. 2A, in the epoxy ring, the bond between one carbon C and oxygen O is broken and the epoxy ring is opened. The ring-opened oxygen O can be regarded as a monovalent anion, and the ring-opened carbon C can be regarded as a monovalent cation.

The drawings on the left side and the right side of FIG. 2B are schematic diagrams showing states before and after the two epoxy rings that are in the ring-opened state are coupled. As shown on the left side of FIG. 2B, in the two epoxy rings in the ring-opened state, the reaction proceeds so that the anionized oxygen O and the cationized carbon C of each epoxy ring are bonded to each other. As a result, as shown on the right side of FIG. 2B, the carbon C constituting one epoxy ring and the carbon C constituting the other epoxy ring were connected via oxygen O, and two prepolymers were formed. Will polymerize. By this ring-opening polymerization reaction, for example, a large number of prepolymers shown in (Chemical Formula 1) are polymerized, and the curing of the epoxy adhesive proceeds.

In this way, the ring structure is opened to form a cation and an anion. By binding the ring-opened structures to each other, the prepolymer is crosslinked to form a polymer. For example, in the above-mentioned benzooxy-based adhesive, a benzooxy-based resin polymer is formed by opening and polymerizing the benzooxy ring. Further, in the imide-based adhesive, the polymer (polyimide) of the imide-based resin is formed by ring-opening and polymerization of the cyclic imide structure. Note that these ring-opening polymerization reactions can be appropriately controlled by the temperature and addition of a curing agent or the like.

The pH indicator 12 is a reagent that can show the pH (hydrogen ion index) of a liquid component by changing the optical characteristics such as fluorescence and color. For example, in the step of bonding using the mixed adhesive 20 (resin composition 10) or the like, liquid components such as water (aqueous solution) contained in the sweat, saliva, exhaled breath, etc. of the worker and liquid components such as water in the atmosphere are mixed and bonded. It may be mixed in the agent 20. Further, as will be described later, the mixed adhesive 20 may include a liquid component such as a dispersion solvent of the pH indicator 12 and other liquid additives. By kneading the pH indicator 12, it is possible to visually detect changes in the pH value and liquid properties (acidic, neutral, alkaline, etc.) of such liquid components contained in the mixed adhesive 20. is there.

As the pH indicator 12, a fluorescence indicator whose fluorescence changes according to pH is used. The fluorescent indicator includes a fluorescent substance that absorbs light having a predetermined wavelength and emits fluorescence. The fluorescence indicator is a reagent in which, for example, the wavelength band (spectrum) of fluorescence, fluorescence intensity, and the like change according to the pH of the liquid component, and can be said to be a pH-dependent fluorescent agent. For example, the fluorescence of the fluorescent indicator is excited by irradiating with excitation light having a wavelength corresponding to the type of reagent.

As the fluorescent indicator, various commercially available fluorescent reagents and fluorescent dyes can be used. Alternatively, a single fluorescent reagent/fluorescent dye derivative, a reagent in which a plurality of fluorescent reagents/fluorescent dyes are appropriately mixed, and the like may be used. For example, as an example of an inexpensive fluorescent indicator having remarkable pH sensitivity, fluorescein, rhodamine B, Ageladine A trifluoracetate (manufactured by AdipoGen), LysoGlow84 (manufactured by AdipoGen) and the like can be mentioned.

FIG. 3 is a diagram showing the chemical structure of fluorescein, which is an example of the pH indicator 12. Fluorescein (also referred to as resorcinolphthalein) is used as a coloring agent for bath salts because it is safe for the human body, and is a drug designated as Yellow No. 201 in Japan. By using fluorescein, for example, it is possible to form the mixed adhesive 20 which is easy to handle and has high safety. The upper left, lower center, and upper right of FIG. 3 show the chemical structures of fluorescein in acidic, neutral, and alkaline environments.

For example, as shown in the upper left of FIG. 3, in an acidic environment, fluorescein forms a lactone ring (5-membered ring containing one oxygen atom). In this state, fluorescein fluoresces relatively weakly with a yellow wavelength band. Further, in a neutral environment, as shown in the lower center of FIG. 3, the lactone ring is opened to become COOH. In this state, fluorescence having a red wavelength band is mixed with fluorescence of fluorescein. Further, in an alkaline environment where sodium hydroxide (NaOH) and the like are present, as shown in the upper right of FIG. 3, an ionic structure in which H is removed from COOH is formed. In this state, fluorescein emits a strong fluorescence having a yellow-green (yellow+green) wavelength band.

Fluorescein is easily dissolved in a solvent such as water, methanol or ethanol. It is possible to disperse fluorescein substantially uniformly by dissolving the fluorescein in these solvents (liquid components) and then kneading the unmixed adhesive 21. Note that these solvents can be removed by, for example, heat treatment in the curing process of the mixed adhesive 20.

Rhodamine B (also referred to as Acid Red, Eosin, Phloxine, and Basic Violet 10) is also used as a coloring agent used for dyeing foods, and is a drug designated as Red No. 213 in Japan. By using Rhodamine B, it is possible to form the mixed adhesive 20 or the like having sufficiently high safety.

The color tone of the fluorescence of rhodamine B does not depend much on pH and has a red to orange wavelength band. On the other hand, it is known that the fluorescence emission intensity has a peak at pH 6 (weakly acidic), and it can be used as a pH indicator by combining with fluorescence intensity measurement, for example. Rhodamine B can be easily dissolved in water, ethanol, etc., and can also be dissolved in lipids and oils. Thereby, for example, the type of solvent can be easily changed according to the type and application of the adhesive, and excellent versatility can be exhibited.

Ageladine A trifluoracetate (TFA) is a fluorescent indicator that emits strong blue-green fluorescence at pH 4 to pH 8 and weak fluorescence in an alkaline environment. In this case, for example, by detecting the site where the fluorescence intensity is lowered, it is possible to easily detect the site that has transitioned to the alkaline environment.

LysoGlow84 emits fluorescence in the wavelength band having a peak at about 440 nm (strong green green blue) at pH 3 to pH 6, and fluorescence in the wavelength band having a peak at about 400 nm (strong blue green blue) at pH 8 to pH 13. It is a fluorescent indicator that emits. In this case, for example, by detecting a site having a strong blue color, it is possible to easily detect a site that has transitioned to an alkaline environment.

The type of fluorescent indicator is not limited. Fluorescent reagents and fluorescent dyes are considered to have some pH sensitivity depending on the pH value of the dispersion solvent, regardless of their types. Therefore, it is possible to use any fluorescent reagent/fluorescent dye as a fluorescent indicator by appropriately detecting a change in spectrum (fluorescent color) or a change in fluorescence intensity according to the pH sensitivity of each drug.

Among them, as in the above-mentioned examples, for example, a fluorescent indicator that shows a remarkable transition from acidic (or neutral) to alkaline (for example, transition from pH 6 to pH 8 or higher) is preferably used. By using such a fluorescent indicator, it becomes possible to easily detect alteration of the mixed adhesive 20 described later. In addition to this, for example, a fluorescent indicator may be appropriately selected according to the color, fluorescent property, liquid property, etc. of the unmixed adhesive 21.

The weight ratio of the fluorescent indicator and the unmixed adhesive 21 (weight of fluorescent indicator/weight of unmixed adhesive 21) is preferably set to 0.1% or more and 5% or less. By setting the weight ratio to 0.1% or more, it is possible to achieve the fluorescence intensity required for measurement. Further, by setting the weight ratio to 5% or less, it is possible to avoid the unnecessary use of the fluorescent indicator. More preferably, the fluorescent indicator and the unmixed adhesive 21 are mixed in a weight ratio of 0.1% or more and 2% or less. By mixing the fluorescent indicator in this range, it is possible to realize the accuracy of fluorescence observation practically required and to reduce the cost of the fluorescent indicator.

Even when the weight ratio of the fluorescent indicator is 0.1% or less, for example, the accuracy of the fluorescence observation can be improved by increasing the intensity of the excitation light. Further, the upper limit of the weight ratio of the fluorescent indicator is not limited to the above example, and may be appropriately set, for example, within a range in which the adhesive property or the like does not change. In addition, the weight ratio of the fluorescent indicator and the unmixed adhesive 21 may be appropriately set according to, for example, the fluorescence intensity of the fluorescent indicator to be used.

Further, as the pH indicator 12, a color change indicator whose color changes according to pH may be used. The color change indicator is a reagent whose color changes depending on the pH of the liquid component. For example, in the mixed adhesive 20 in which the color change indicator is kneaded, the color of the mixed adhesive 20 itself changes due to the change in the color of the color change indicator.

As the color change indicator, various commercially available reagents can be used. The coloration indicator may be kneaded into the unmixed adhesive 21 as a powder, or may be dispersed in a predetermined solvent such as water or alcohol and then kneaded into the unmixed adhesive 21. As an example of the color change indicator, Table 1 below shows the chemical names of representative color change indicators, the low pH side color, the color change range, and the high pH side color in this order.

The type of color change indicator is not limited. For example, as shown in Table 1, each color change indicator has a predetermined color change range in which color changes depending on pH. Further, the color change of each color change indicator also varies. For example, among the examples shown in Table 1, a color change indicator that markedly shows a transition from acidic (or neutral) to alkaline (for example, transition from pH 6 to pH 8 or higher) is preferably used. By using such a color change indicator, it becomes possible to easily detect alteration of the mixed adhesive 20 described later. For example, a color change indicator having properties suitable for the color and liquidity of the unmixed adhesive 21 or the type of solvent may be appropriately selected.

Further, the ratio of mixing the coloration indicator and the unmixed adhesive 21 is not limited. For example, the minimum mixing amount of the color change indicator and the like may be set so that the operator can visually recognize the color change in the color change range. Further, for example, the maximum mixing amount of the color change indicator or the like may be set within a range in which the adhesive property or the like of the unmixed adhesive 21 does not deteriorate. In addition, the mixing amount of the color change indicator may be appropriately set so that a desired change in the color change range can be detected.

In addition to the unmixed adhesive 21 and the pH indicator 12 described above, the mixed adhesive 20 may be mixed with predetermined additives. For example, additives such as an adhesiveness imparting agent (adhesion imparting agent), an antioxidant and a thickener may be mixed. Alternatively, various fillers for the purpose of reinforcing strength and preventing curing shrinkage may be added. Also, a latent curing agent or the like for curing the synthetic resin may be added.

Further, the mixed adhesive 20 is not limited to the paste-like form as shown in FIG. For example, the mixed adhesive 20 may be a liquid having a lower viscosity than, for example, a paste. In this case, the mixed adhesive 20 may be sprayable. Alternatively, the mixed adhesive 20 molded in a semi-cured state with the pH indicator 12 mixed may be used. In this case, a sheet-shaped mixed adhesive 20 (film-shaped adhesive) or the like may be molded. In addition, the present technology is applicable regardless of the form of the mixed adhesive 20.

[Curing failure prediction method]
FIG. 4 is a flowchart showing an example of a method for predicting a curing failure using the mixed adhesive 20. FIG. 5 is a schematic diagram showing an example of an adhesive layer containing the mixed adhesive 20. Hereinafter, a method of predicting a curing failure that detects a curing failure point before the bonding step will be described.

First, the adhesive layer 31 containing the mixed adhesive 20 is formed on the object to be bonded 30 (step 101). The adhesive layer 31 is a layer made of, for example, the mixed adhesive 20 for adhering the object to be adhered 30 and another member (object to be adhered). As the mixed adhesive 20, an adhesive containing a fluorescent indicator as the pH indicator 12 (fluorescent adhesive), an adhesive containing a color-changing indicator (color-forming adhesive), or the like is used. In the present embodiment, the bonding target object 30 corresponds to the bonding target object. The adhesive layer 31 formed on the object 30 to be bonded corresponds to a bonding layer.

FIG. 5 schematically illustrates a plate-shaped object to be bonded 30 on which the adhesive layer 31 is formed. For example, the paste-like mixed adhesive 20 is applied to the object to be bonded 30 using a spatula, a brush, or the like to form the adhesive layer 31. Alternatively, the liquid mixed adhesive 20 may be applied or sprayed to form the adhesive layer 31. Further, the adhesive layer 31 may be formed by disposing the sheet-shaped mixed adhesive 20 (film-shaped adhesive) on the surface of the object 30 to be adhered.

As described above, in step 101, the adhesive layer 31 composed of the mixed adhesive 20 containing the unmixed adhesive 21 that is cured by ring-opening polymerization on the object to be bonded 30 and the pH indicator 12 whose optical characteristics change according to pH. Is provided. The method of forming the adhesive layer 31 is not limited.

The adhesive layer 31 may include an altered portion 32 in which the properties of the mixed adhesive 20 are altered and the ring-opening polymerization reaction (see FIG. 2) does not proceed properly. In the altered portion 32, the ring-opening polymerization reaction becomes poor, and there is a high possibility that curing failure, adhesion failure, or the like will occur. Therefore, it can be said that the altered portion 32 is a portion where a curing failure is predicted.

FIG. 6 is a diagram for explaining an example of a chemical reaction in the altered portion 32. The altered portion 32 is generated, for example, in the step of forming the adhesive layer 31 by adhering salt or the like contained in sweat, exhalation, saliva or the like of an operator to the adhesive layer 31. FIG. 6 schematically illustrates, as an example of the chemical reaction in the altered portion 32, a chemical reaction between an aqueous solution (sweat or the like) in which sodium chloride NaCl is dissolved and an epoxy adhesive. Note that the following description is also applicable to other adhesives of a type that cures by ring-opening polymerization (benzooxy adhesives, imide adhesives, etc.).

As shown on the left side of FIG. 6, in the sodium chloride aqueous solution (NaCl aq), hydrogen ion H ⁺ and hydroxide ion OH ⁻ ionized from water H ₂ O, and sodium ion Na ⁺ and chloride ion liberated from sodium chloride. The ion Cl ⁻ is included. Among these ions, the hydrogen ion H ⁺ combines with the anionized oxygen O of the opened epoxy ring. Further, the chloride ion Cl ⁻ binds to the cationized carbon C of the opened epoxy ring.

As a result, as shown on the right side of FIG. 6, hydrogen H and chlorine Cl are bonded to the opened epoxy ring, and the polymerization reaction with other epoxy rings does not occur. That is, the epoxy ring is consumed by the hydrogen ion H ⁺ and the chloride ion Cl ⁻ contained in the sodium chloride aqueous solution. The consumed epoxy ring can no longer establish a polymerization reaction with other epoxy rings, resulting in poor curing and poor adhesion.

Further, sodium ion Na ⁺ and hydroxide ion OH ⁻ in the sodium chloride aqueous solution remain without reacting with the epoxy ring. Therefore, the concentrations of sodium ion Na ⁺ and hydroxide ion OH ^{− in} the altered portion 32 increase. As a result, the pH value of the altered portion 32 increases and the altered portion 32 shifts to an alkaline environment.

As described above, in the synthetic resin 11 (adhesive) that cures by ring-opening polymerization, the salt structure and the aqueous solution thereof may adhere to the ring structure, which may make it difficult to properly proceed the polymerization reaction. Such a portion becomes the altered portion 32. In addition, the pH changes and the pH shifts to the alkaline side as the ring structure is consumed. Therefore, the altered portion 32 is a portion having a different pH value than the other portions.

Examples of the salt contained in the attached matter such as sweat include sodium chloride NaCl, mineral salts such as potassium chloride KCl, calcium chloride CaCl ₂ , and magnesium chloride MgCl ₂ . Regarding these components, similarly to the reaction described with reference to FIG. 6, a reaction that consumes the ring structure and changes the pH value may occur.

An area surrounded by a dotted line shown in FIG. 5 is an adhesion area 33 to which the sweat or the like of the worker adheres. As described above, the attachment area 33 is an area that may become the altered portion 32. Whether or not the mixed adhesive 20 in the adhesion region 33 has actually deteriorated can be determined by the steps described below.

In the uncured state of the mixed adhesive 20, the optical characteristics of the adhesive layer 31 are observed to detect the altered portion 32 of the adhesive layer 31 (step 102). This step is typically performed before adhering another member (object to be adhered) to the adhesive layer 31. The uncured state of the mixed adhesive 20 is, for example, a state in which a curing treatment for curing the mixed adhesive 20 has not been performed, or a state before the curing time of the mixed adhesive 20 has elapsed.

FIG. 7 is a schematic diagram showing an example of a process of detecting the altered portion 32. In FIG. 7A, a pH-dependent fluorescent adhesive 20 a, which is a mixed adhesive 20 in which a fluorescent indicator is mixed as the pH indicator 12, is used. When a fluorescence indicator is used, fluorescence characteristics such as color and intensity of fluorescence are observed as the optical characteristics of the adhesive layer 31.

The fluorescence characteristic is typically observed by irradiating the adhesive layer 31 with predetermined excitation light 35 using the excitation light source 34 or the like to excite the fluorescence of the fluorescent adhesive 20a (fluorescent indicator). That is, when the pH indicator 12 is a fluorescent indicator, the step of observing the optical characteristics of step 102 is a step of irradiating the adhesive layer 31 with predetermined excitation light and observing the fluorescence of the fluorescent indicator.

As the excitation light source 34, for example, an ultraviolet black light capable of irradiating ultraviolet rays is used. By using an ultraviolet black light or the like, it is possible to easily and inexpensively observe fluorescence. Besides this, for example, an arbitrary excitation light source 34 capable of emitting the excitation light 35 matched with the absorption spectrum of the fluorescent indicator or the like may be used.

Hereinafter, a case where fluorescein is used as the fluorescent indicator and an epoxy adhesive having a liquidity of about pH 6 (weakly acidic) is used as the unmixed adhesive 21 will be described. In this case, as described with reference to FIG. 3 and the like, yellow weak fluorescence is observed in the portion of the adhesive layer 31 in the weakly acidic environment. On the other hand, strong yellow-green fluorescence is observed at the site where the environment has changed to an alkaline environment.

For example, the worker irradiates the adhesive layer 31 with ultraviolet black light or the like, and visually observes the fluorescence generated in the adhesive layer 31. In the example shown in FIG. 7A, strong yellow-green fluorescence (bright gray region) is observed in the adhesion region 33. On the other hand, weak yellow fluorescence (dark gray region) is observed outside the adhesion region 33. In this way, when the fluorescence of fluorescein is induced by using the ultraviolet black light, the portion where good adhesiveness is expected emits yellow fluorescence. On the other hand, the part where sweat or the like adheres and changes to alkalinity to cause poor adhesion emits yellowish green fluorescence. For this reason, it is possible to easily discriminate a place where good adhesion is obtained and a place where adhesion is poor.

From these observation results, the altered portion 32 that has transitioned to the alkaline environment is detected. For example, in FIG. 7A, a region (adhesion region 33) where strong yellow-green fluorescence is observed is detected as the altered portion 32. Thus, by using the mixed adhesive 20 in which the fluorescent indicator (fluorescein) is mixed, it is possible to visually identify a change in the pH of the adhesive layer 31 and the like. As a result, it becomes possible to easily detect the location (deteriorated portion 32) that causes poor curing or poor adhesion before the adhesion.

When another fluorescent indicator is used, the altered portion 32 can be detected by identifying the difference in the fluorescent characteristics (color, intensity, etc.) of the fluorescent indicator used. For example, in the case of a fluorescent indicator such as LsoGlow84 in which the color of fluorescence changes between an acidic environment and an alkaline environment, the altered portion 32 is detected by distinguishing the color difference. Alternatively, in a fluorescent indicator such as Rhodamine B or Ageladine A whose fluorescence intensity is reduced in an alkaline environment, a region where the fluorescence is weak is detected as the altered portion 32. In addition to this, it is possible to easily detect the altered portion 32 by appropriately detecting the change in the fluorescence characteristic according to the difference in pH.

In FIG. 7B, a pH-dependent color-developing adhesive 20b, which is a mixed adhesive 20 in which a color-changing indicator is mixed as the pH indicator 12, is used. In this case, the color of the adhesive layer 31 itself is observed as the optical characteristic of the adhesive layer 31. That is, when the pH indicator 12 is a color indicator, the step of observing the optical characteristics in step 102 is the step of observing the color of the adhesive layer 31.

For example, it is assumed that a mixed adhesive 20 in which a colorless or white epoxy adhesive having a liquidity of about pH 6 (weakly acidic) and bromothymol blue (BTB solution) are mixed is used. In this case, the mixed adhesive 20 itself is colored in yellow due to the weakly acidic environment (see Table 1). On the other hand, when the worker's sweat or the like adheres and the epoxy ring is consumed, the adhered portion changes to an alkaline environment and is colored blue.

In the example shown in FIG. 7B, the adhesion area 33 is an area colored in blue (dark gray area), and the area outside the adhesion area 33 is an area colored in yellow (light gray area). In this case, the region colored in blue (adhesion region 33) is detected as the altered portion 32. As described above, by using the color change indicator, it is possible to easily visually detect the altered portion 32 in which the epoxy ring has been consumed. Further, since it is not necessary to use an ultraviolet Brack light or the like, it is possible to reduce the detection cost of the altered portion 32.

Even if the epoxy adhesive is not colorless or white, the color of the mixed adhesive 20 changes according to the difference in pH. The altered portion 32 is detected from this color change. Even if another color change indicator is used, the altered portion 32 can be easily detected by identifying the color difference of the color change indicator (mixed adhesive 20) depending on the pH.

As described above, by using the mixed adhesive 20 in which the pH indicator 12 such as the fluorescent indicator and the color indicator is mixed, the altered portion 32 in the adhesive layer 31 can be detected easily and at low cost. Further, by removing the detected mixed adhesive 20 of the altered portion 32 and applying a new mixed adhesive 20, it is possible to eliminate in advance a portion having a high possibility of poor curing (see FIG. 9C). .. This makes it possible to sufficiently suppress the occurrence of curing failure.

In addition, although the case where the worker's sweat etc. adhered was demonstrated above, in addition to this, the case where salt content may be mixed is considered. For example, when the work place is adjacent to the coast, salt contained in the sea breeze may be mixed. Alternatively, salt contained in fertilizers and pesticides may be mixed near the agricultural land. As described above, it is considered that salt or the like is mixed from the air in the work place, and for example, the entire adhesive layer 31 may become the altered portion 32.

Even in such a case, by using the mixed adhesive 20, it is possible to properly detect the alteration of the adhesive layer 31 and prevent the occurrence of curing failure. For example, by comparing the optical characteristics of the clean mixed adhesive 20 (standard sample) containing no salt and the like with the optical characteristics of the adhesive layer 31, it is possible to identify whether or not the adhesive layer 31 has deteriorated. .. Thereby, even when the adhesive layer 31 is entirely shifted to the alkali side, the change can be detected in advance. This makes it possible to avoid large-scale curing defects and adhesion defects.

[Method for manufacturing bonded body]
FIG. 8 is a flowchart showing an example of a method for manufacturing a joined body using the mixed adhesive 20. FIG. 9 is a schematic view showing an example of a manufacturing process of a joined body using the mixed adhesive 20. 9A to 9E are schematic diagrams showing the steps 201 to 205 shown in FIG. Below, with reference to Drawing 8 and Drawing 9, a manufacturing method of joined object 37 using mixed adhesive 20 is explained.

First, the adhesive layer 31 containing the mixed adhesive 20 is formed on the object to be bonded 30 (step 201, FIG. 9A). That is, the adhesive layer 31 including the mixed adhesive 20 containing the unmixed adhesive 21 that cures by ring-opening polymerization and the pH indicator 12 whose optical characteristics change depending on the pH is provided on the adhesion target 30. FIG. 9A schematically illustrates a plate-shaped object to be bonded 30 on which an adhesive layer 31 of the mixed adhesive 20 is formed.

After the formation of the adhesive layer 31, in the uncured state of the mixed adhesive 20, the optical characteristics of the adhesive layer 31 are observed to detect the altered portion 32 of the adhesive layer 31 (step 202, FIG. 9B). In the adhesive layer 31 shown in FIG. 9B, the shaded area is detected as the altered portion 32.

The steps of step 201 and step 202 are steps of detecting a portion (altered portion 32) having a high possibility of curing failure, and executing the method of predicting curing failure described with reference to FIG. 4 and the like. Step 201 and step 202 are executed in the same manner as, for example, step 101 and step 102 described above.

When the altered portion 32 is detected, the mixed adhesive 20 contained in the altered portion 32 is removed (step 203, FIG. 9C). As described above, at the timing when the altered portion 32 is detected, the mixed adhesive 20 is in an uncured state before the curing reaction is completed. The operator can remove the mixed adhesive 20 contained in the area detected as the altered portion 32 by using, for example, a spatula or a waste cloth.

For example, in FIG. 9C, the mixed adhesive 20 is removed over a region slightly wider than the region where the altered portion 32 is detected until the surface of the bonding target object 30 is visible. This makes it possible to reliably remove the mixed adhesive 20 that may cause poor polymerization. If only the surface of the adhesive layer 31 is altered, it is possible to remove only the mixed adhesive 20 on the surface. Besides, the method of removing the mixed adhesive 20 is not limited.

The area where the mixed adhesive 20 has been removed is filled with the clean mixed adhesive 20 (step 204, FIG. 9D). For example, the unused mixed adhesive 20 is newly applied to the area where the deteriorated mixed adhesive 20 is removed. As a result, as shown in FIG. 9D, it is possible to form the adhesive layer 31 made of the clean mixed adhesive 20. When a sheet-shaped mixed adhesive 20 (adhesive sheet) or the like is used, the clean mixed adhesive 20 can be replaced by appropriately replacing the adhesive sheet in the portion where the altered portion 32 is detected.

After newly filling the mixed adhesive 20, the step of detecting the altered portion 32 (see step 202) may be executed again. That is, the optical characteristics of the adhesive layer 31 filled with the mixed adhesive 20 may be checked again. As a result, overlooking of the deteriorated mixed adhesive 20 (altered portion 32) and the like are eliminated, and highly reliable adhesion can be realized.

As described above, Steps 203 and 204 are steps of replacing the detected mixed adhesive 20 in the altered portion 32 with a new mixed adhesive 20. This makes it possible to eliminate the mixed adhesive 20 that is likely to cause poor curing or poor adhesion, and keep the adhesive layer 31 clean.

The bonded object 36 is bonded to the bonding layer 31 to form a bonded body 37 (step 205, FIG. 9E). For example, as shown in FIG. 9E, the adhered object 36 is brought into contact with the adhesive layer 31. For example, appropriate pressure is applied to the object to be bonded 30 and the object to be bonded 36 so that a sufficient adhesive force is exerted. Further, for example, heat treatment or the like for curing the adhesive layer 31 is performed. In addition to this, various curing treatments are performed according to the characteristics of the mixed adhesive 20 (unmixed adhesive 21) used. As a result, a bonded body 37 in which the bonding target object 30 and the bonding target object 36 are bonded via the bonding layer 31 is formed.

As described above, in the method for manufacturing the joined body 37 according to the present embodiment, a portion (altered portion 32) that is predicted to cause poor curing or poor adhesion is detected. Then, a bonded body 37 of the object to be adhered 30 and the object to be adhered 36 is manufactured using the adhesive layer 31 from which the altered portion 32 is removed. As a result, it is possible to supply a highly reliable bonded body 37 in which defective bonding and reduction in strength are suppressed.

As described above, the mixed adhesive 20 (resin composition 10) according to the present embodiment contains the unmixed adhesive 21 (synthetic resin 11) that cures by ring-opening polymerization and the pH indicator 12 that changes optical characteristics. The unmixed adhesive 21 contains a ring structure that causes ring-opening polymerization. For example, when salt contained in sweat, exhaled breath, or the like adheres to the synthetic resin, the ring structure is consumed and the pH of the adhesion site changes. By detecting the optical characteristics of the pH indicator 12 according to this change in pH, it becomes possible to detect a location where curing failure is predicted. As a result, it becomes possible to easily suppress the occurrence of curing failure.

As a method of detecting the curing failure of the adhesive, a nondestructive inspection using ultrasonic waves or the like, or a method of arranging a magnetic body having a stress-magnetic characteristic in the adhesive layer to detect the adhesion failure (Patent Document 1), etc. Is mentioned. These methods are methods for detecting a location where curing is poor or adhesion is poor after the adhesive is cured. Therefore, it is difficult to predict the defective portion before the adhered portions are bonded together.

In the present embodiment, the mixed adhesive 20 in which the pH indicator 12 is mixed with the unmixed adhesive 21 that cures by ring-opening polymerization is used. The pH of the mixed adhesive 20 (non-mixed adhesive 21) shifts to the alkaline side at a location where polymerization is defective due to sweat of the worker (see FIG. 6 and the like). For this reason, by adding the pH indicator 12 for detecting a defective polymerization portion as a change in pH, it is predicted that curing failure or adhesion failure will occur before the adhered areas are bonded ( It is possible to detect the altered portion 32).

Further, by removing the mixed adhesive 20 that has become the altered portion 32 and replacing it with a clean mixed adhesive 20, it is possible to sufficiently avoid the occurrence of defective curing itself. As a result, it is possible to avoid discarding the adhered members, re-adhesion, and the like. As a result, it is possible to avoid an increase in manufacturing cost and the like without causing a time loss.

Further, as described with reference to FIG. 7 and the like, in the mixed adhesive 20, it is possible to easily detect the altered portion 32 by observing the optical characteristics of the pH indicator 12. For example, when a fluorescent indicator is used, the fluorescent characteristic is observed using a general black light or the like. When a color change indicator is used, the color of the mixed adhesive is observed as it is. As described above, in the present embodiment, specialized equipment (such as ultrasonic wave detection and magnetic characteristic detection) for detecting the altered portion 32 is unnecessary, and the cost required for detecting the altered portion 32 can be sufficiently reduced. is there. As a result, it is possible to realize low cost and highly reliable prediction of curing failure.

<Second Embodiment>
The resin composition of the second embodiment according to the present invention will be described. In the following description, the description of the parts similar to the configuration and operation of the resin composition 10 (mixed adhesive 20) described in the above embodiment will be omitted or simplified.

FIG. 10: is a schematic diagram which shows the structural example of the laminated member and laminated body which concern on 2nd Embodiment. In the present embodiment, the resin composition 50 and the fibrous material are used to form the laminated member 60 that is a fiber-reinforced composite material (FRPs). A laminated body 61 made of a fiber-reinforced composite material is formed using the laminated member 60.

In FIG. 10A, a sheet-shaped laminated member 60 is schematically illustrated as an example. 10B schematically shows a rectangular parallelepiped laminated body 61 formed by laminating the sheet-shaped laminated members 60 shown in FIG. 10A. The shapes of the laminated member 60 and the laminated body 61 are not limited to the examples shown in FIGS. 10A and 10B.

The resin composition 50 is a resin mixture in which a pH indicator 52 is mixed with a synthetic resin 51. The synthetic resin 51 is a type of resin that cures by ring-opening polymerization, and is the base material of the fiber-reinforced composite material described above. As the synthetic resin 51, for example, a resin for a structural material including an epoxy resin, a benzooxy resin, an imide resin, or the like is used. The pH indicator 52 is mixed with the synthetic resin 51 before forming the laminated member 60. As the pH indicator 52, for example, like the pH indicator 12 described in the first embodiment, a pH-dependent fluorescent indicator, a color indicator, or the like is used.

The fiber material functions as a reinforcing fiber of the fiber-reinforced composite material. Examples of the fiber material include inorganic fibers such as carbon fibers, glass fibers, silica fibers, metal fibers and ceramic fibers, and organic synthetic fibers such as polyamide fibers, polyester fibers, polyolefin fibers and novoloid fibers (phenol fibers). Etc. are used. Further, a fibrous material such as a chip shape, a cloth shape, or a non-woven cloth shape is appropriately used. The type and form of the fiber material are not limited.

The laminated member 60 is a member (prepreg) for manufacturing the laminated body 61, and the resin composition 50 (synthetic resin 51) is used in an uncured state. For example, a cured product in which the laminated members 60 are bonded to each other is formed by laminating a plurality of laminated members 60 and performing curing treatment (heating, pressurizing, etc.) on the whole. A cured product obtained by laminating the plurality of laminated members 60 becomes a laminated body 61.

That is, it can be said that the laminated member 60 is a structural member that constitutes the laminated body 61 and also functions as a joining member (joining layer) for joining to another adjacent laminated member 60. In the present embodiment, the laminated body 61 corresponds to a joined body, and the laminated member 60 that is a fiber-reinforced composite material corresponds to a joined layer in the laminated body 61. In addition, each of the laminated members 60 used for manufacturing the laminated body 61 is an object to be joined that constitutes the laminated body 61 (joined body). In addition, when viewed from a certain laminated member 60, the other laminated member 60 joined to the laminated member 60 is an object to be joined.

The laminated body 61 formed by using the laminated member 60 is used as a structural member made of a fiber reinforced material in various fields such as automobiles, ships, aerospace, and construction. Of course, the application of the laminated member 60 (laminated body 61) is not limited to these fields.

The laminated member 60 is typically produced by impregnating a fibrous material with the resin composition 50 to bring the resin composition 50 into a semi-cured state. For example, the synthetic resin 51 and the pH indicator 52 are dispersed in a predetermined solvent to produce the resin composition 50 having low viscosity. The resin composition 50 having a low viscosity is impregnated into a sheet-shaped fiber material such as carbon fiber cloth, and then the whole is heated to remove the solvent. As a result, a sheet-shaped laminated member 60 as shown in FIG. 10A is generated.

Further, by appropriately adjusting the hardness of the resin composition 50, it is possible to appropriately configure the freely bendable laminated member 60, the relatively hard laminated member 60, and the like. In addition, the method for producing the laminated member 60 and the shape, size, hardness, etc. of the laminated member 60 are not limited.

As described above, the laminated member 60 contains the synthetic resin 51 (prepolymer) that is cured by ring-opening polymerization and the pH indicator 52. Therefore, for example, as described in the first embodiment with reference to FIG. 6 and the like, when the ring structure of the synthetic resin 51 is consumed by the attachment of salt or the like, the pH in the attachment region changes, The optical characteristics of the indicator 52 change. Therefore, by observing the optical characteristics of the pH indicator 52, it is possible to detect the site where the ring structure is consumed (altered part).

FIG. 11 is a flowchart showing an example of a method for manufacturing the laminated body 61 using the laminated member 60. Below, the manufacturing process of the laminated body 61 is demonstrated with reference to FIG.

First, a plurality of laminated members 60 are generated (step 301). For example, a required number of laminated members 60 are generated according to the shape and size of the laminated body 61 to be manufactured. The timing of generating the laminated member 60 is not limited. For example, the laminated member 60 may be generated immediately before the laminated body 61 is manufactured, or the laminated member 60 generated in advance may be stored in a cool dark place. You can leave it.

As described above, the laminated member 60 is both a structural member and a bonding layer. Therefore, when the laminated member 60 is produced, the laminated member 60 is provided with a bonding layer made of the resin composition 50 containing the synthetic resin 51 and the pH indicator 52. Thus, it can be said that the step of forming the laminated member 60 is a step of forming a bonding layer containing the resin composition 50 on the bonding target.

Next, the optical characteristics of the laminated member 60 are observed in the uncured state of the synthetic resin 51 to detect the altered portion of the laminated member 60 (step 302). As a result, it is checked whether or not an altered portion has occurred in the laminated member 60 (bonding layer).

For example, it is assumed that the worker's sweat, saliva, breath, and the like adhere to the laminated member 60 during the work of handling the laminated member 60. In this case, in the adhesion region, the ring structure of the synthetic resin 51, which is the base material of the laminated member 60, is consumed, and an altered portion may occur. Further, for example, when the laminated member 60 is stored, it is conceivable that salt or the like contained in the outside air adheres, the ring structure of the synthetic resin 51 is consumed, and the entire laminated member 60 becomes an altered portion.

As described above, in the manufacturing process of the laminated body 61, for example, a part of the laminated member 60 may be an altered portion or one laminated member 60 may be an altered portion. In the present embodiment, the altered portion of the laminated member 60 is detected by appropriately observing the optical characteristics of the pH indicator 52 contained in the laminated member 60.

FIG. 12 is a schematic diagram showing an example of a process of detecting the altered portion 32. In FIG. 12A, a resin composition 50a in which a fluorescent indicator is mixed as the pH indicator 52 is used. In this case, the predetermined excitation light 35 is applied to the laminated member 60 to excite the fluorescence of the fluorescent indicator. The excited fluorescence is observed by the operator's eyes and the like, and the altered portion 32 is detected based on the observation result such as the color and intensity of the fluorescence.

In FIG. 12B, the resin composition 50b in which a color indicator is mixed as the pH indicator 52 is used. In this case, the change in the color of the surface and the inside of the laminated member 60 is visually observed. The altered portion 32 is detected based on the color change of the laminated member 60 itself.

Observation of these optical properties is typically performed throughout the laminate 60. For example, in the sheet-shaped laminated member 60, the optical characteristics of both surfaces are observed. Further, this step is performed for all the laminated members 60 laminated as the laminated body 61, for example. Other than this, the method of observing the optical characteristics is not limited. In the present embodiment, the steps 301 and 302 described above are steps for executing the method for predicting curing failure in the manufacturing process of the laminate.

When the altered portion 32 is detected in the laminated member 60, the laminated member 60 in which the altered portion 32 is detected is replaced (step 303). For example, the laminated member 60 in which the altered portion 32 has been detected is replaced with a clean laminated member 60 in which the altered portion 32 has not been detected. That is, it can be said that the detected resin composition 50 of the altered portion 32 is replaced with a new resin composition 50. As a result, it is possible to eliminate in advance the portion that is likely to have poor curing or poor bonding before performing the curing treatment or the like, and it is possible to improve the quality of the laminated body 61.

It is also possible that the site where the altered portion 32 is detected is appropriately removed and replaced with another member (the laminated member 60 or the like). This makes it possible to maintain the quality of the laminated body 61 while suppressing the cost of the laminated member 60, for example. In addition, when the detected size of the altered portion 32 is so small that there is no practical problem in constructing the laminated body 61, the laminated member 60 may be used as it is without being replaced. As a result, it is possible to reduce the wasted laminated member 60.

In this way, step 303 can be said to be a step of preparing the laminated member 60 capable of properly forming the laminated body 61 according to the detection result of the altered portion 32. The laminated member 60 is not replaced when the altered portion 32 is not detected in the laminated member 60.

Next, the plurality of laminated members 60 are laminated (step 304). Here, the laminated member 60 prepared in the above process (such as a clean laminated member 60 from which the altered portion 32 is excluded) is used.

For example, the laminated member 60 is stacked on a flat pedestal. This makes it possible to form a rectangular parallelepiped-shaped laminated body 61 as shown in FIG. 10B. Alternatively, the laminated member 60 is laminated along a molding die that matches the shape of the laminated body 61. The shape of the molding die is not limited, and it is possible to use a molding die having a three-dimensional shape including a curved surface or the like. The mold for molding may be a male type or a female type. It is possible to form the laminated body 61 having an arbitrary shape by using a molding die.

A curing process is performed on the stacked plurality of laminated members 60 to form a laminated body 61 (step 305). Typically, a curing process of heating and pressurizing the laminated members 60 as a whole is performed. In the present embodiment, in the step of stacking a plurality of laminated members 60 and curing the whole (steps 304 and 305), another laminated member 60 is joined to the laminated member 60 which is a joining layer to form a laminated body 61. It becomes a process to do.

When the laminated member 60 is heated and the temperature rises, the viscosity of the synthetic resin 51 as the base material decreases. The synthetic resin 51 having reduced viscosity functions as a bonding layer that bonds the respective laminated members 60, that is, an adhesive that adheres the laminated members 60 to each other. For example, the entire laminated member 60 is pressed while the viscosity of the base material is reduced. As a result, the adhesion between the adjacent laminated members 60 is improved, and it becomes possible to firmly join the members.

Further, as the temperature rises, the curing reaction by ring-opening polymerization of the synthetic resin 51 is promoted. For example, by maintaining the heated/pressurized state for a predetermined time, the curing reaction proceeds in a state where the respective laminated members 60 are in close contact, and the adjacent laminated members 60 are joined. As a result, a cured product (laminate 61) is formed by integrally curing the plurality of laminated members 60.

For the curing treatment, a hot press device that heats and pressurizes the target object, an autoclave that can heat the target object by raising the pressure in the heating chamber, and the like are appropriately used. The parameters for curing treatment such as heating temperature, heating time, pressurizing timing, and pressurizing pressure are not limited. For example, each parameter may be appropriately set depending on the type of the synthetic resin 51, the size/shape of the laminated body 61, and the like so that the laminated body 61 can be appropriately formed. Further, as the curing treatment, both heating and pressurization may be performed as described above, or either one of heating and pressurization may be performed.

In the above, the example in which the altered portion 32 of the laminated member 60 is detected before the laminated member 60 is laminated has been described. The invention is not limited to this. For example, when the laminated members 60 are laminated, the altered portion 32 may be detected at the same time. In this case, for example, every time a new laminated member 60 is laminated, the optical characteristics of the laminated member 60 are observed and the presence or absence of the altered portion 32 is checked. As a result, it becomes possible to reliably eliminate the contamination and the like that occur during stacking. In addition, the process of detecting the altered portion 32 may be performed at any timing before the curing process of step 305 is performed, for example.

As described above, in the present embodiment, the laminated body 61 is formed using the laminated member 60 including the synthetic resin 51 (the resin composition 50) containing the pH indicator 52 as the base material. Further, in the manufacturing process of the laminated body 61, the altered portion 32 of the laminated member 60 is detected and eliminated before the curing process is performed. As a result, it is possible to sufficiently suppress the occurrence of curing failure, and it is possible to provide a high-quality laminate 61.

In addition, in the present manufacturing process, it is possible to detect the cause of the curing failure or the adhesion failure during the lamination of the fiber reinforced composite materials (FRPs). This makes it possible to quickly identify a problem such as a working environment at the time of stacking or a storage environment of the stacked member 60. In this way, it is possible to easily identify the cause of the defect, so that it is possible to improve the manufacturing process.

<Other embodiments>
The present invention is not limited to the embodiments described above, and various other embodiments can be realized.

In the example shown in FIG. 1, the mixed adhesive 20 in which the pH indicator 12 is mixed with the unmixed adhesive 21 that functions as an adhesive alone has been described. For example, the present technology can be applied even when a two-component adhesive or the like is used.

FIG. 13 is a schematic view showing an example of an adhesive kit according to another embodiment. The adhesive kit 70 has a main agent 71 containing a synthetic resin that cures by ring-opening polymerization, and a curing agent 72 that cures the synthetic resin contained in the main agent 71. A two-component adhesive is formed by mixing the main agent 71 and the curing agent 72 of these adhesive kits at a predetermined ratio.

A typical example of the two-component adhesive is a two-component epoxy adhesive. In the two-component epoxy adhesive, the main agent 71 is an epoxy adhesive containing an epoxy resin as a main component. As the curing agent 72, various curing agents capable of curing an epoxy adhesive such as amines, polyamide resins, imidazoles, polymercaptan curing agents, etc. are used. Specific configurations of the main agent 71 and the curing agent 72 are not limited. The adhesive is not limited to the two-component epoxy adhesive, and for example, a two-component imide adhesive or benzooxy adhesive may be used.

In the adhesive kit 70, at least one of the main agent 71 and the curing agent 72 is mixed with a pH indicator whose optical characteristics change according to pH. As the pH indicator, for example, the fluorescent indicator, the color indicator, etc. described in the first and second embodiments are used.

In the example shown in FIG. 13, a pH indicator is mixed with the main agent 71. For example, the main agent 71 may be mixed in a larger proportion than the hardener 72. Therefore, by mixing the pH indicator with the main agent 71 in advance, it is possible to form a two-component adhesive agent in which the pH indicator is sufficiently dispersed and mixed. Further, for example, the curing agent 72 may be mixed with a pH indicator. Alternatively, a pH indicator may be mixed in both the main agent 71 and the curing agent 72. In either case, the pH indicator is contained in the two-component adhesive agent in which the main agent 71 and the curing agent 72 are mixed.

As described above, by using the two-liquid type adhesive containing the pH indicator, it is possible to easily detect the altered portion (altered portion) due to the inclusion of salt or the like. As a result, it is possible to sufficiently avoid the curing failure, the adhesion failure, and the like using the two-component adhesive agent.

FIG. 14 is a schematic diagram showing an example of a curing failure detection device according to another embodiment. The curing failure detection device 80 is a device that detects the altered portion 32 from the adhesive layer 31 shown in FIG. 5 or the like, or the uncured bonding layer 81 such as the laminated member 60 shown in FIG. 10A or the like. The curing failure detection device 80 has an optical sensor 82 and a detection unit 83.

The optical sensor 82 observes the optical characteristics of the pH indicator contained in the bonding layer 81. That is, the optical sensor 82 observes the optical characteristics of the bonding layer 81 made of a resin composition containing a synthetic resin that cures by ring-opening polymerization and a pH indicator whose optical characteristics change according to pH. In the curing failure detection device 80, the optical sensor 82 corresponds to an observation unit.

The optical sensor 82 is used by being fixed at a predetermined position, for example. Alternatively, the optical sensor 82 may be configured so that the operator can hold it by hand. As the optical sensor 82, for example, a digital camera capable of color-imaging the bonding layer 81 or an infrared camera for detecting fluorescence is used. A black light or the like may be used as the illumination of the optical sensor 82. Besides, the specific configuration of the optical sensor 82 is not limited.

The detection unit 83 is a functional block including a computer such as a PC (Personal Computer) or a mobile terminal. The detection unit 83 detects the altered portion 32 of the bonding layer 81 based on the observation result of the optical characteristics. The observation result of the optical characteristics is, for example, an image of the bonding layer 81 taken by the optical sensor 82. By performing a predetermined image processing on the image of the bonding layer 81, the altered portion 32 in the bonding layer 81 is detected.

For example, as described with reference to FIGS. 7 and 12, the altered portion 32 is a portion in which the color of fluorescence or the color of the material itself is changed compared to other portions. The part where the color changes in this way is detected as the altered part 32. Further, for example, when the type of the pH indicator is known, the altered portion 32 is detected by comparing with the color stored in advance. Other than this, the method of detecting the altered portion 32 is not limited, and the altered portion 32 may be detected using, for example, machine learning.

The detection unit 83 also outputs the detection result of the alteration unit 32. For example, the range of the altered portion 32 in the image under observation is emphasized and displayed on a display (not shown) or the like. Alternatively, a message, a buzzer sound, or the like indicating that the alteration unit 32 has been detected may be presented. As a result, the operator can easily confirm that the altered portion 32 has occurred in the bonding layer 81 that is the observation target.

The curing failure detection device 80 can be used not only when the bonding layer 81 is uncured but also when the bonding layer 81 is cured. For example, when the pH of the altered portion 32 does not change before and after curing, it is possible to detect the altered portion 32 that has failed to cure by observing the optical characteristics of the pH indicator. Therefore, even after the adhesive, the laminated member, or the like is cured, it is possible to perform a nondestructive inspection on the place where the curing failure occurs.

In the above embodiment, the synthetic resin (resin composition) containing the pH indicator was used as an adhesive or a laminated member. Besides, the use of the synthetic resin is not limited. For example, a pH indicator may be contained in a jointing agent such as a caulking agent or a sealing agent, or a synthetic resin used in putty, paint or the like. In addition, the present invention can be applied to any synthetic resin of the type that is cured by ring-opening polymerization.

Among the characteristic parts according to the present invention described above, it is possible to combine at least two characteristic parts. That is, the various characteristic portions described in the respective embodiments may be arbitrarily combined without distinction between the respective embodiments. Further, the various effects described above are merely examples and are not limited, and other effects may be exhibited.

In the present disclosure, “same”, “equal”, “orthogonal” and the like are concepts including “substantially the same”, “substantially equal”, “substantially orthogonal” and the like. For example, a state included in a predetermined range (for example, a range of ±10%) based on “perfectly the same”, “perfectly equal”, “perfectly orthogonal”, or the like is also included.

10, 50... Resin composition 11, 51... Synthetic resin 12, 52... pH indicator 20... Mixed adhesive 21... Unmixed adhesive 30... Adhesive object 31... Adhesive layer 32... Deformed part 37... Bonded body 60... Laminate Member 61... Laminated body 70... Adhesion kit 80... Curing failure detection device

Claims (14)

A resin composition comprising a synthetic resin that cures by ring-opening polymerization and a pH indicator whose optical properties change according to pH. The resin composition according to claim 1, wherein
The synthetic resin is a resin composition which is a base material of an adhesive or a fiber-reinforced composite material. The resin composition according to claim 1 or 2, wherein
The pH indicator is a fluorescent indicator in which fluorescence changes according to the pH. The resin composition according to claim 1 or 2, wherein
The pH indicator is a coloration indicator that changes color depending on the pH. The resin composition according to any one of claims 1 to 4, wherein
The resin composition, wherein the synthetic resin is at least one of an epoxy resin, a benzooxy resin, or an imide resin. A bonding layer made of a resin composition containing a synthetic resin that cures by ring-opening polymerization and a pH indicator whose optical characteristics change according to pH is provided on the bonding target,
A method for predicting curing failure, which comprises observing the optical characteristics of the bonding layer and detecting an altered part of the bonding layer in a state where the resin composition is uncured. The method for predicting curing failure according to claim 6, wherein
The synthetic resin is an adhesive,
The bonding layer is an adhesive layer formed on the bonding target. The method for predicting curing failure according to claim 6, wherein
The synthetic resin is a base material of the fiber-reinforced composite material,
The bonding layer is a laminated member that becomes the fiber-reinforced composite material. The curing failure prediction method according to any one of claims 6 to 8,
The pH indicator is a fluorescent indicator whose fluorescence changes according to the pH,
The step of observing the optical property is a method of predicting a curing failure in which the bonding layer is irradiated with a predetermined excitation light and the fluorescence of the fluorescent indicator is observed. The curing failure prediction method according to any one of claims 6 to 8,
The pH indicator is a color change indicator that changes color depending on the pH,
The step of observing the optical property is a method for predicting a curing failure in which the color of the bonding layer is observed. The method for predicting curing failure according to any one of claims 6 to 10,
The synthetic resin is at least one of an epoxy resin, a benzooxy resin, or an imide resin. A bonding layer made of a resin composition containing a synthetic resin that cures by ring-opening polymerization and a pH indicator whose optical characteristics change according to pH is provided on the bonding target,
In the uncured state of the resin composition, to detect the altered portion of the bonding layer by observing the optical characteristics of the bonding layer,
Replacing the resin composition of the detected altered portion with a new resin composition,
A method for manufacturing a bonded body, comprising forming a bonded body by bonding an object to be bonded to the bonding layer. A main agent containing a synthetic resin that cures by ring-opening polymerization, and a curing agent that cures the synthetic resin, and at least one of the main agent and the curing agent is mixed with a pH indicator whose optical properties change according to pH. Adhesive kit. An observation section for observing the optical characteristics of a bonding layer made of a resin composition containing a synthetic resin that is cured by ring-opening polymerization and a pH indicator whose optical characteristics change according to pH.
A curing failure detection device comprising: a detection unit that detects an altered portion of the bonding layer based on an observation result of the optical characteristics.