Method for handling hardening material and hardening material package

Abstract

To reduce a moisture content of a curable material composed of an adhesive or a resin before curing, and inexpensively and simply secure a dry state while suppressing dew condensation.SOLUTION: A method for handling a curable material includes: putting, into a vacuum container, a curable material that is composed of an adhesive or a resin before being cured by a water-soluble curing agent, or an adhesive, or a resin before being cured through polymerization reaction with moisture, and has a moisture absorption property; vacuum-freezing and drying the curable material; making a temperature exceed a dew point as of in a take-out environment in the vacuum container; and then taking out the curable material from the vacuum container and curing the curable material.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for handling a cured material made of an adhesive or resin before curing, to a cured material package including the cured material and a container capable of storing the cured material, and to an adhesive structure bonded by an adhesive. [Background technology]

[0002] Epoxy resins and benzooxy resins, which are often used in two-component epoxy adhesives and the parent phase of fiber-reinforced plastics (FRPs), are hardened by being mixed with a curing agent such as an amine, which causes the epoxy group or benzooxy group to open and polymerize.

[0003] However, since the resin itself is hygroscopic and most hardeners are water-soluble, ice grows when frozen and turns into water droplets when returned to room temperature. Alternatively, when the resin is removed from the freezer, condensation occurs and moisture is contained, attached, or absorbed, causing the hardener to dissolve in the water, resulting in an inconsistency in the resin-hardener equivalence ratio. This can result in poor polymerization, which can lead to poor hardening and adhesion.

[0004] Similarly, cyanoacrylate adhesives, also known as instant adhesives, are stored in a freezer below the freezing point of water because the presence of moisture causes a polymerization reaction. As a result, if they are used at low temperatures below the dew point without being allowed to return to room temperature, condensation will form, causing rapid hardening and reducing performance, or they may harden without coming into contact with the object to be adhered, resulting in no adhesive strength.

[0005] Representative conventional methods for avoiding the effects of condensation and moisture include returning the resin to room temperature by spraying dry air or nitrogen gas onto it, placing the resin in a dry atmosphere chamber when removing it from the freezer and waiting until the temperature returns to room temperature, enclosing the resin together with a desiccant, and, in the case of vacuum-packed resin, opening the pack after the resin has returned to room temperature without opening it. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Toray Industries, Inc., "TORAYCA (registered trademark) prepreg," [online], [searched August 3, 2020], Internet: https: / / www.torayca.com / download / pdf / prepreg.pdf [Non-Patent Document 2] Toagosei Co., Ltd., "Instant adhesive Aron Alpha (registered trademark)", [online], [searched August 3, 2020], Internet <http: / / www.toagosei.co.jp / products / functional / catalog / pdf / index_pdf_01.pdf> Summary of the Invention [Problem to be solved by the invention]

[0007] Conventional techniques assume indirect methods to maintain a dry state, but do not directly control the amount of moisture in the resin or adhesive or on the surface, so a method to reliably guarantee a dry state is required.

[0008] Furthermore, even in cases where condensation and the like were successfully suppressed, the moisture in the resin would collect and freeze in places, but when the frozen areas thawed, they would turn into a liquid phase and contain liquid droplets, causing adverse effects of moisture.

[0009] Furthermore, there is a problem in that the desiccants, dry air and nitrogen are expensive.

[0010] In view of the above circumstances, an object of the present invention is to reduce the moisture content of a curable material made of an adhesive or resin before curing, thereby preventing condensation and ensuring a dry state inexpensively and simply. [Means for solving the problem]

[0011] A method for handling a hardening material according to one embodiment of the present invention includes the steps of: A hygroscopic curing material consisting of an adhesive or resin before being cured by a water-soluble curing agent, or an adhesive or resin before being cured that undergoes a polymerization reaction with moisture, is placed in a vacuum container and vacuum freeze-dried; After being brought to a temperature above the dew point of the removal environment in the vacuum vessel, the curable material is removed from the vacuum vessel and allowed to cure.

[0012] According to the present invention, the moisture content of the cured material is extremely low because the cured material is vacuum freeze-dried. Furthermore, the cured material is cured at a temperature above the dew point, so the cured material does not condense. This prevents the hygroscopic cured material from dissolving in water. As a result, the mechanical properties of the cured material can be improved.

[0013] The step of bringing the hardening material to a temperature above the dew point in the vacuum vessel includes heating the hardening material while monitoring the temperature of the hardening material.

[0014] According to the present invention, since the hardening material is heated while the temperature of the hardening material is monitored, the hardening material can be easily and stably heated to an appropriate temperature.

[0015] The curable material is heated to a temperature exceeding the dew point in the vacuum vessel, and then secondarily heated to about 30° C. in the vacuum vessel. Thereafter, the curable material is removed from the vacuum vessel and cured.

[0016] According to the present invention, since the hardening material is subjected to secondary heating, the moisture in the hardening material can be removed more reliably.

[0017] The secondarily heated hardening material is taken out of the vacuum vessel and transferred directly to a baking step, where it is baked and hardened.

[0018] According to the present invention, the hardened material is hardened by firing immediately after being taken out, thereby making it possible to improve the mechanical properties of the hardened material after firing.

[0019] The curable material is an epoxy adhesive, an epoxy resin, a benzoxy adhesive, a benzoxy resin, a cyanoacrylate resin, or a cyanoacrylate adhesive.

[0020] These curable materials are hygroscopic. Since the hygroscopic curable materials are vacuum freeze-dried, the moisture content of the curable materials is extremely low. Furthermore, since the curable materials are cured at a temperature above the dew point, the curable materials do not condense. This prevents the hygroscopic curable materials from dissolving in water. As a result, the mechanical properties of the cured materials can be improved.

[0021] The epoxy adhesive is a bisphenol A type adhesive.

[0022] The bisphenol A type adhesive may contain chlorine.

[0023] The hardening material package according to one aspect of the present invention comprises: A freeze-dried cured material having hygroscopic properties, the hardened material being made of an adhesive or resin before being cured by a water-soluble curing agent, or an adhesive or resin before being cured that undergoes a polymerization reaction with moisture; A vacuum container capable of storing the hardened material in a vacuum-frozen state; Equipped with:

[0024] In this way, the hardening material package can be transported to a location where the hardening material is to be used, and the hardening material package can be taken out of the vacuum container at the location where the hardening material is to be used. Therefore, the hardening material can be used at the location where the hardening material is to be used without being deteriorated.

[0025] The freeze-dried hardened material has a fracture toughness value after hardening that is 1.2 times or more higher than that of a hardened material hardened without going through a freeze-drying process.

[0026] Freeze drying the cured material improves the post-curing fracture toughness value of the cured material.

[0027] The freeze dried hardened material is a bisphenol A type adhesive.

[0028] The adhesive structure according to one embodiment of the present invention comprises: The bonded structure is bonded with a bisphenol A type adhesive, and has a fracture toughness value 1.2 times or more higher than that of the hardened material that is hardened without going through the vacuum freeze-drying process. Effect of the Invention

[0029] According to the present invention, the moisture content of the curable material made of an adhesive or resin before curing can be reduced, and the dry state can be ensured inexpensively and simply while preventing condensation.

[0030] The effects described herein are not necessarily limited, and may be any of the effects described in the present invention. [Brief description of the drawings]

[0031] [Figure 1] 1 is a flow chart illustrating a method for handling hardening material according to one embodiment of the present invention. [Diagram 2] 1 shows a schematic diagram of how to handle a hardening material. [Diagram 3] 1 shows an example of a hardenable material package. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0033] I. First embodiment

[0034] 1. How to handle hardening materials

[0035] Fig. 1 is a flow chart showing a method for handling a hardening material according to an embodiment of the present invention, and Fig. 2 is a schematic diagram showing the method for handling a hardening material.

[0036] Step S1: Preparation of hardening material

[0037] A curable material is prepared. The curable material has hygroscopicity. The curable material is made of an adhesive or resin before curing that is cured by a water-soluble curing agent. Alternatively, the curable material is made of an adhesive or resin before curing that undergoes a polymerization reaction with moisture. The curable material is a synthetic resin, an adhesive, a film-like adhesive, or an instant adhesive. Specifically, the curable material is an epoxy adhesive, an epoxy resin, a benzoxy adhesive, a benzoxy resin, a cyanoacrylate resin, or a cyanoacrylate adhesive. The epoxy adhesive is a bisphenol A type adhesive. The bisphenol A type may contain chlorine. The curable material is, for example, a CFRP (Carbon Fiber Reinforced Plastics) prepreg roll. The CFRP prepreg roll is a roll-shaped CFRP prepreg (a sheet-shaped material in which carbon fibers are impregnated with resin) wound around a bobbin (core material). Prepreg is a material used for main structural members such as the fuselage, main wings, and tail of an aircraft, and for propellers of ships and submarines.

[0038] Step S2: Freezing the hardening material

[0039] The hardening material is frozen so that it does not harden. Specifically, the hardening material is frozen by storing it in a freezer at about -18°C to -24°C. The hardening material may be frozen at about -18°C or lower. The hardening material can be stored in a freezer at about -18°C for about half a year. Preferably, the hardening material is frozen at -20°C or lower.

[0040] Step S3: Vacuum freeze-drying (freeze-drying) of the hardened material

[0041] The hardening material is removed from the freezer. The hardening material is placed in a vacuum container. The vacuum container is a container (packaging container) that can store the hardening material in a vacuum-packed state by vacuum freezing. A temperature sensor (e.g., a thermocouple) is attached to a predetermined position of the frozen hardening material. The frozen hardening material with the temperature sensor attached is placed in a vacuum freeze dryer. The vacuum freeze dryer is depressurized by a vacuum pump. Then, in the vacuum freeze dryer, ice contained in the frozen hardening material sublimes and becomes water vapor, and the moisture contained in the hardening material is removed. The vacuum freeze dryer has a cold trap (also called a cooling trap). The cold trap may be a part of the freezer. The cold trap removes water vapor in the vacuum freeze dryer. The vacuum freeze dryer is gradually heated while monitoring the temperature of the hardening material using a temperature sensor. After confirming that the temperature of the hardening material exceeds the dew point (dew point in the vacuum freeze dryer), secondary heating (secondary drying) is performed to about 30°C (a temperature that does not affect the hardening material). The second heating evaporates the water remaining in the hardened material (water bound between molecules), further removing the moisture contained in the hardened material. This causes the hardened material placed in the vacuum container to be vacuum lyophilized (freeze-dried). As a result, a hardened material package is produced.

[0042] FIG. 3 shows an example of a hardenable material package.

[0043] The hardening material package 10 is a package in which the vacuum freeze-dried hardening material 11 is sealed in a vacuum container 12. When the hardening material before vacuum freeze-drying is a gel-like resin such as a prepreg, the vacuum freeze-dried hardening material 11 has fine porous exhaust flow paths. The hardening material 11 is a roll-shaped CFRP prepreg wound around a bobbin (core material).

[0044] Step S4: Take out

[0045] The cured material package is removed from the freeze dryer and may be transported to the point of use.

[0046] Step S5: Use hardening material

[0047] The curable material package is placed in a thermostatic chamber. The thermostatic chamber is heated to heat the freeze-dried curable material contained in the curable material package. The temperature of the curable material is heated while monitoring the temperature of the curable material. For example, a temperature sensor (e.g., a thermocouple) is attached to a predetermined position of the curable material package that can measure the temperature of the vacuum-packed curable material in the vacuum container (packaging container), and the thermostatic chamber is gradually heated while monitoring the temperature of the curable material using the temperature sensor. The vacuum-packed curable material is heated to a temperature exceeding the dew point in the removal environment (atmospheric pressure) in the vacuum container (packaging container) by heating. Thereafter, the vacuum-packed curable material is secondarily heated to about 30°C in the vacuum container (packaging container) to thaw the curable material. The curable material package is removed from the thermostatic chamber. The freeze-dried curable material is removed from the vacuum container (packaging container) of the curable material package. The freeze-dried curable material is transferred directly to a baking process, where it is baked to perform hardening and bonding operations.

[0048] At this time, the curing material is in a dry state and is at a temperature higher than the dew point, so condensation does not occur. As a result, adverse effects on curing and adhesion, such as elution of the curing agent and polymerization reactions caused by moisture in the liquid phase, are resolved. This makes it possible to completely and easily avoid poor curing, polymerization, and adhesion caused by moisture, even when performed by an inexperienced worker.

[0049] 2. Comparative test

[0050] The curing material used was 3M's AF555M bisphenol A type (containing chlorine) epoxy adhesive. The CFRP material used was Toray Industries' T800S / 3900-2B 8-ply unidirectional laminate. The vacuum freeze dryer used was Tokyo Rikakikai's EYELA FDU-1200 freeze dryer. The analytical measuring instrument used was Shimadzu's Autograph AG-X universal testing machine. The test method used was the DCB (Double Cantilever Beam) test method described in JIS K7086 "Test method for interlaminar fracture toughness of carbon fiber reinforced plastics."

[0051] As an example, a curing material "AF555M Bisphenol A type (containing chlorine) epoxy adhesive manufactured by 3M" was frozen at about -20°C, vacuum freeze-dried, and thawed according to the handling method of the curing material according to this embodiment (steps S1 to S5 in FIG. 1). The moisture content of the curing material after thawing was measured with a Karl Fischer moisture meter and was about 0.1%. The curing material thawed after vacuum freeze-drying was sandwiched between two CFRP materials, baked and hardened to bond the two CFRP materials together, thereby producing an adhesive structure according to the example (drying treatment using the freeze-drying method).

[0052] As a comparative example, the same curing material "AF555M Bisphenol A type (containing chlorine) epoxy adhesive manufactured by 3M" was frozen at about -20°C and thawed. When thawed, the curing material absorbs moisture from the air. The moisture content of the curing material after thawing was measured with a Karl Fischer moisture meter and was about 1%. The frozen and thawed curing material was sandwiched between two CFRP materials and baked to harden and bond the two CFRP materials together to produce an adhesive structure according to the comparative example (normal construction).

[0053] In taking measurements, it is desirable to prepare three or more test pieces and use their average value as the measured value, taking into consideration the inevitable variation in measurements. Therefore, a total of six test pieces were produced, including three test pieces of the adhesive structure according to the embodiment and three test pieces of the adhesive structure according to the comparative example, and the average value of each set of three was used as the measured value for comparison. The manufacturing conditions of the test pieces of the adhesive structure according to the embodiment and the test pieces of the adhesive structure according to the comparative example were the same, except for the method of handling the hardened material according to this embodiment. A total of six test pieces were tested under the same conditions specified by JIS K7086. Fracture toughness value G IC The calculation of was performed using the modified compliance calibration method recommended by JIS K7086. Table 1 shows the fracture toughness values ​​(kJ / m 2 ) is shown.

[0054] [Table 1]

[0055] As shown in the top three rows of Table 1, the fracture toughness values ​​G IC is 0.679(kJ / m 2 ), 0.773(kJ / m 2 ), 0.599(kJ / m 2 The fracture toughness values ​​G of the three test pieces of the bonded structure according to the embodiment IC is 1.087(kJ / m 2 ) 0.941(kJ / m 2 ), 0.974(kJ / m 2 As shown in the bottom row of Table 1, the fracture toughness values ​​G IC The average value of 2 ) and the fracture toughness values ​​G IC The average value of 2) The freeze-dried hardened material (Example) had a fracture toughness value after hardening that was approximately 1.46 times higher (46% improvement) than the hardened material hardened without going through the freeze-drying process (Comparative Example). From the above, it can be seen that the mechanical properties were improved by using the freeze-dried hardened material.

[0056] II. Second embodiment

[0057] In the first embodiment, a hardening material is placed in a vacuum container (a container capable of storing the hardening material in a vacuum frozen state), and the hardening material placed in the vacuum container is vacuum freeze-dried to produce a hardening material package (a package in which the vacuum freeze-dried hardening material is sealed in a vacuum container). This hardening material package may be transported to a point where the hardening material is used. When the hardening material is used, the hardening material sealed in the hardening material package is thawed. In contrast, in the second embodiment, a frozen hardening material is vacuum freeze-dried and thawed when used. In a use case, the hardening material in a frozen state is transported to a point where the hardening material is used, and the hardening material is vacuum freeze-dried and thawed at the point where the hardening material is used. Therefore, in the second embodiment, it is not necessary to produce a hardening material package. In the following description, the points already described will be omitted, and the differences will be mainly described. In the second embodiment, the vacuum freeze dryer corresponds to the vacuum container (a container capable of storing the hardening material in a vacuum frozen state).

[0058] Please refer to Figure 1. Step S1 (preparing the hardened material) and step S2 (freezing the hardened material) are the same as the process of the first embodiment.

[0059] Step S3: Vacuum freeze-drying (freeze-drying) of the hardened material

[0060] The hardened material is removed from the freezer. A temperature sensor (e.g., a thermocouple) is attached to a predetermined position of the frozen hardened material. The frozen hardened material with the temperature sensor attached is placed in a vacuum freeze dryer. The vacuum freeze dryer is depressurized by a vacuum pump. Then, in the vacuum freeze dryer, ice contained in the frozen hardened material sublimes into water vapor, and the moisture contained in the hardened material is removed. The vacuum freeze dryer has a cold trap (also called a cooling trap). The cold trap may be a part of the freezer. The cold trap removes the water vapor in the vacuum freeze dryer. The vacuum freeze dryer is gradually heated while monitoring the temperature of the hardened material using a temperature sensor. After confirming that the temperature of the hardened material exceeds the dew point (dew point in the removal environment (atmospheric pressure)), secondary heating (secondary drying) is performed up to about 30°C (a temperature that does not affect the hardened material). The secondary heating evaporates the water (water bonded between molecules) remaining in the hardened material, and the moisture contained in the hardened material is further removed. This causes the hardened material to be lyophilized (freeze-dried).

[0061] Step S4: Take out

[0062] The hardened freeze dried material is removed from the freeze dryer.

[0063] Step S5: Use hardening material

[0064] The vacuum freeze-dried hardened material is then transferred directly to the baking process, where it is baked to harden and adhere.

[0065] III. Conclusion

[0066] According to the first and second embodiments, the hardening material is vacuum freeze-dried, so that the moisture content of the hardening material is extremely low. Therefore, when the vacuum freeze-dried hardening material is thawed, the hardening material does not condense, and frost or water droplets do not form. As a result, the hardening material having hygroscopicity does not contain, adhere to, or absorb moisture, so that the hardening material does not dissolve in water. Therefore, the equivalence ratio of the materials contained in the hardening material maintains a consistent value. In other words, the hardening material is not easily altered. As a result, polymerization is not easily defective, and hardening and adhesion are not easily defective. In addition, in the vacuum freeze-drying process, the hardening material is put from the freezer to the vacuum freeze-dryer, and the temperature of the hardening material is monitored, so that even an unskilled worker can easily achieve a dry state comparable to that of a skilled worker. By vacuum freeze-drying the hardening material, condensation can be eliminated, and even a small amount of moisture that was originally contained in the hardening material can be dehydrated. Since the hardening material is dehydrated by vacuum freeze-drying after the fact in this way, expensive drying and dehydration processes are not required even in the manufacturing process of the hardening material (before freezing). This allows the use of an inexpensive synthesis process that produces water during a chemical reaction, thereby reducing the manufacturing cost of the hardened material. This embodiment can be used in any field that uses hardened materials that require refrigeration or freezing. For example, this embodiment can be used in technical fields such as manufacturing, maintenance, repair, and overhaul that use FRP prepregs and adhesives.

[0067] Although the embodiments and modified examples of the present technology have been described above, the present technology is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the gist of the present technology. [Explanation of symbols]

[0068] 10: Hardening material package 11: Vacuum freeze dried hardened material 12: Vacuum container S1: Preparation of hardening material S2: Freezing of hardening material S3: Vacuum freeze drying of hardened materials S4: Eject S5: Use of hardening materials

Claims

1. A curable material that contains a water-soluble curing agent and is made of an adhesive or resin before being cured by the water-soluble curing agent, and has hygroscopic properties; or A hardening material that is made of an adhesive or resin before hardening that undergoes a polymerization reaction with moisture and has hygroscopic properties Place in a vacuum container and freeze-dry. After the temperature in the vacuum vessel exceeds the dew point of the removal environment, the curable material is removed from the vacuum vessel and cured. How to handle hardening materials.

2. 2. A method for handling the hardening material according to claim 1, comprising the steps of: The step of bringing the hardening material to a temperature above the dew point in the vacuum vessel includes heating the hardening material while monitoring the temperature of the hardening material. How to handle hardening materials.

3. A method for handling the hardening material according to claim 1 or 2, comprising the steps of: The hardening material is heated to a temperature exceeding the dew point in the vacuum vessel, and then the material is secondarily heated to about 30° C. in the vacuum vessel. The hardening material is then removed from the vacuum vessel and hardened. How to handle hardening materials.

4. 4. A method for handling the hardening material according to claim 3, comprising the steps of: The second heated hardening material is removed from the vacuum vessel and baked to harden it. How to handle hardening materials.

5. A method for handling a hardening material according to any one of claims 1 to 4, comprising the steps of: The curable material is an epoxy adhesive, an epoxy resin, a benzoxy adhesive, a benzoxy resin, a cyanoacrylate resin, or a cyanoacrylate adhesive. How to handle hardening materials.

6. 6. A method for handling a hardening material according to claim 5, comprising the steps of: The epoxy adhesive is a bisphenol A type adhesive. How to handle hardening materials.

7. A freeze-dried cured material that contains a water-soluble curing agent and is made of an adhesive or resin before curing that is cured by the water-soluble curing agent, and has hygroscopic properties; or a freeze-dried cured material that is made of an adhesive or resin before curing that undergoes a polymerization reaction with moisture and has hygroscopic properties; A vacuum container capable of storing the hardened material in a vacuum-frozen state; Equipped with The freeze-dried hardened material is sealed in the vacuum vessel. Hardening material package.

8. 8. The hardenable material package of claim 7, The freeze-dried hardened material is a bisphenol A type adhesive. Hardening material package.

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