JP3811484B2 - Low temperature curable epoxy resin composition for prepreg and prepreg - Google Patents

Description

  The present invention relates to an epoxy resin composition for a low-temperature curable prepreg and a prepreg that can remarkably improve the troublesome work that has been performed by conventional hand lay-ups and that can be used in a wide range of fields such as sports / leisure and civil engineering architecture. Is.

  Conventionally, in repairing or reinforcing civil engineering structures, particularly concrete structures, steel plate bonding methods and concrete reinforcement methods have been widely adopted. However, recently, in terms of workability, safety, and construction period, a method of repairing and reinforcing a fabric, uniaxially arranged fiber sheet, or a prepreg impregnated with an epoxy resin in advance is applied to the surface of the structure. Has come to attract attention. In Patent Document 1, a method of repairing or reinforcing using a resin-impregnated long fiber prepreg is proposed, but it is necessary to cure at a high temperature with an infrared lamp or an electric heater after being attached. On the other hand, Patent Document 2 proposes a method of repairing or reinforcing a long-fiber carbon fiber sheet by applying a room temperature curing type epoxy resin by a hand lay-up method. However, in this method, it is quite difficult to uniformly impregnate the entire fiber sheet with resin so that there are no voids, and it involves a very troublesome operation. Further, since the hand lay-up method is adopted, the odor is intense and it cannot be said that it is good for health and safety.

In contrast, Patent Document 3 uses a long-fiber prepreg in which fibers are impregnated with an epoxy resin that is cured in advance at 70 ° C. or higher. Further, Patent Document 4 uses an epoxy resin that does not substantially contain a curing agent. The use of impregnated long fibers has been proposed, but in order to cure at room temperature, a room temperature curing type epoxy resin solution dissolved in thinner or MEK or a room temperature curing type curing agent solution is applied to the surface of the prepreg. However, it does not solve the inconvenience and safety and health problems of the hand lay-up method, and has a drawback that it tends to be poorly cured.
JP-A-1-197532 JP-A-3-224901 JP-A-3-224966 JP-A-5-39673

  In view of such a current situation, the present invention eliminates problems such as safety and hygiene, troublesomeness, and curing characteristics in the repair and reinforcement of structures using fiber sheets or prepregs compared to conventional hand lay-up methods. An object of the present invention is to provide an epoxy resin composition for a low-temperature curable prepreg and a prepreg that can be used.

  In order to solve the above-mentioned problems, the present inventor first tried to encapsulate a room temperature curable curing agent such as an amine to obtain a pressure curable type. However, it turned out to be very difficult, and as a result of extensive investigation, it was adsorbed to the clathrate compound without directly encapsulating the room temperature curing type curing agent such as amine, The present invention was completed by combining high alcohol and the like.

That is, the present invention is a low-temperature curing type prepreg epoxy resin composition comprising the following components A, B and C as essential components.
A: Epoxy compound B having at least two or more glycidyl groups in one molecule; an amine compound having active hydrogen is adsorbed, and an organic high compound having a melting point or softening point of 40 to 100 ° C. on the whole or a part thereof Inclusion compound C coated with molecules; a compound that can serve as a displacer of amine compounds for inclusion compound B component

  Furthermore, the present invention is a low temperature curable prepreg characterized in that a fiber is impregnated with the epoxy resin composition for a low temperature curable prepreg described above.

  According to the present invention, compared with the conventional hand lay-up method using a room temperature curable epoxy resin, the low temperature curable prepreg has drastically improved problems such as annoying work, safety and hygiene, and curing characteristics. Epoxy resin composition and low-temperature curable prepreg, which are very useful industrially.

  The present invention will be described in detail below. The epoxy compound used as the component A in the present invention is not particularly limited as long as it has at least two or more glycidyl groups in one molecule, and any compound can be used. For example, bisphenol A type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol F type epoxy resin, other alicyclic epoxy resins, bisphenol S type epoxy resin, etc. Or 2 or more types can be mixed and used.

  Examples of the bisphenol A type epoxy resin include espoxy SA-115, espoxy SA-134, espoxy SA-011, espoxy SA-019, espoxy SA-7020 (manufactured by Nippon Steel Chemical Co., Ltd.), epicoat 828, and epicoat 834. , Epicoat 1001, Epicoat 1004 (above, manufactured by Yuka Shell Epoxy Co., Ltd.), Araldite GY-250, Araldite GY-260, Araldite 6071 (above, manufactured by Ciba Geigy Japan) are used. it can.

  Examples of the cresol novolac type epoxy resin include espoxy SCN-701P, espoxy SCN-702P, espoxy SCN-703P, espoxy SCN-704P (manufactured by Nippon Steel Chemical Co., Ltd.), Araldite ECN-1273, Araldite ECN-1280 ( As described above, commercially available products such as ESCN-220 series manufactured by Nippon Ciba-Geigy Co., Ltd. or Sumitomo Chemical Co., Ltd. can be used.

  As the phenol novolac type epoxy resin, commercially available products such as Espoxy SPN-638 (manufactured by Nippon Steel Chemical Co., Ltd.), Epicoat 152, Epicoat 154 (above, manufactured by Yuka Shell Epoxy Co., Ltd.) can be used. . As the bisphenol F type epoxy resin, commercially available products such as Epicron 830 (manufactured by Dainippon Ink & Chemicals, Inc.) can be used.

  Next, the B component will be described. First, in the clathrate compound adsorbing an amine compound having active hydrogen, the amine compound used is an amine compound having active hydrogen capable of reacting with an epoxy compound at room temperature, and further adsorbed on the clathrate compound. Anything is possible. For example, primary amines such as ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, secondary amines such as diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, and Polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenediamine, diethylaminopropylamine, tetramethylenebutanediamine, hexamethylenediamine, N-aminoethylpiperazine, metaxylenediamine, aminoethylethanolamine, and more Examples thereof include modified amines such as polyamide polyamines and amine adducts.

  The inclusion compound is not particularly limited as long as it is a porous powder capable of adsorbing the amine compounds. Examples include inorganic substances such as zeolite, montmorillonite, diatomaceous earth, kaolin, mica, activated carbon, and organic substances such as porous polystyrene. can give. Among these, zeolite having a uniform pore size, that is, molecular sieves, is particularly preferable. The average particle size of the clathrate compound is preferably 0.1 to 20 μm. If it is less than 0.1 μm, the clathrate compound aggregates and is difficult to disperse, and conversely tends to cause poor curing. On the other hand, if it exceeds 20 μm, there is a possibility that it will not be uniformly dispersed between the fibers. This is because a defect occurs. The method for adsorbing the amine compound on the clathrate compound is not particularly limited, but for example, a method such as heat treatment or the like on the clathrate compound to activate it and directly adsorb the amine compound or an amine compound. A method of gradually adding an amine compound under a solvent that is difficult to adsorb is common. In the latter case, if reflux is used in combination, it can be adsorbed more quantitatively.

  Next, the amount of the amine compound in the inclusion compound of the component B is preferably 5 to 40% by weight. If it is less than 5%, the effect as a curing agent is small, and it tends to be in an uncured state or very slow in curing. Since the amine compound reacts almost quantitatively with the epoxy compound, a certain amount is required with respect to the epoxy compound. Therefore, if it is less than 5%, it is not desirable because the amount of the inclusion compound which is unnecessary for the reaction and adversely affects the physical properties of the cured product is relatively increased. On the other hand, the upper limit is preferably an amount that is quantitatively adsorbed in the pores of the clathrate compound. However, depending on the case, it may be adsorbed not only in the pores but also on the surface of the clathrate compound. In that case, the reaction proceeds immediately with the epoxy compound, causing a problem in storage stability. Therefore, the adsorption amount of the amine compound should not exceed 40% by weight.

  Next, regarding the amounts of the A and B components, the B component is preferably blended with 10 to 100 parts by weight with respect to 100 parts by weight of the total amount of the A component. When the component B is less than 10 parts by weight, the amount of amine compound as a curing agent is insufficient, and curing is likely to be poor. When the amount exceeds 100 parts by weight, the amount of clathrate compound in a powder state becomes very large, and it becomes difficult to disperse it, and the weight of the composite material increases, which is not preferable.

  Next, as a C component compound that can be a displacer of amine compounds with respect to the B component clathrate compound, the compound generally has an OH group or an SH group, although it varies depending on the type of clathrate compound. Specifically, alcohols, water, and thiols can be mentioned. In the present invention, these compounds function as a purge agent for amine compounds adsorbed in the clathrate compound, and the purged amine compounds react with the A component epoxy compound and cure at room temperature. Therefore, in order to be able to be an expelling agent, it is necessary for the clathrate compound to have a higher adsorption capacity than the amine compound and to be smaller than the pore size of the clathrate compound. Here, the compound that can be used as an expelling agent for the amine compound in the component C is preferably an alcohol compound from the viewpoint of handling, and specific examples thereof include ethyl alcohol, propyl alcohol, butyl alcohol, ethylene glycol, propylene glycol, butane. Examples include, but are not limited to, diol, polyethylene glycol, glycerin, maltitol, and sorbitol.

  The present invention relates to an epoxy resin composition and a prepreg in which the above-mentioned three components A, B and C are blended at the same time and contained in a reinforcing fiber so as not to cause trouble. That is, in the present invention, the inclusion compound of the B component adsorbing the above-described amine compound having active hydrogen can be preserved even if it is blended together with the A and C components before molding the prepreg. It is necessary that the entire periphery or a part of the periphery be coated with an organic polymer having a melting point or softening point of 40 to 100 ° C. In this case, the curing mechanism of the prepreg in the present invention is such that, when the prepreg is molded, the organic polymer film is removed or destroyed by heating the prepreg for a short time at a low temperature. The amine compound is driven out of the clathrate compound, and it reacts with the epoxy compound of component A to be cured. Therefore, in order to ensure the storage stability of the prepreg, the amine compound must be fixed in the inclusion compound until just before curing. In the present invention, in order to perform the fixation, the melting point or the softening point is 40 to 100 ° C. on the whole or a part of the surface of the clathrate compound to which the amine compound is adsorbed, specifically the pore part of the clathrate compound. A means for coating with an organic polymer is used.

  Here, the reason for using an organic polymer instead of an inorganic material as the coating material is that the prepreg is heated at a low temperature for a short time at the time of curing to easily remove or destroy the organic polymer film and to desorb the amine compound. This is because the curing reaction can be started. The organic polymer compound to be used is not particularly limited as long as it has a melting point or softening point of 40 to 100 ° C. and can cover the inclusion compound in the epoxy resin composition of the present invention. And waxes such as hydrocarbons and fatty acid esters. Here, when the melting point or softening point of the organic polymer is lower than 40 ° C., the storage stability at room temperature is deteriorated. Moreover, when it exceeds 100 degreeC, it is not only dangerous, but it is because heating time becomes long or a heating apparatus becomes large.

  The method for coating the organic polymer is not particularly limited, but specific examples include microencapsulation in a coacervation method based on phase separation. For example, as an example, molecular sieves are dispersed by gradually adding an insoluble solvent such as isopropyl alcohol to a benzene solution in which ethylenediamine adsorbing molecular sieves (zeolite) are dispersed and the hydrocarbon wax to be coated is dissolved. It is possible to apply a uniform wax coating on the surface. In this case, the melting point and softening point of the coating material, and the thickness and amount of the coating material can be adjusted by appropriately selecting the type and concentration of the coating material to be added and the insoluble solvent to be added. Here, the amount of the covering material is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the amine compound adsorbing and inclusion compound. When the amount is less than 0.1 part by weight, the fixing effect of the amine compound is small, and the storage stability is deteriorated. On the other hand, when the amount exceeds 20 parts by weight, components unnecessary for curing increase and the physical properties of the composite material deteriorate.

  About the compounding quantity of A, B, and C component used in this invention, B component 10-100 weight part and C component 0.5-20 weight part are mix | blended with respect to 100 weight part of total of A component. Is preferred. When the component B is less than 10 parts by weight, the amount of amine compound as a curing agent is insufficient, and curing is likely to be insufficient. When the amount exceeds 100 parts by weight, the inclusion compound in the powder state becomes very large and dispersion becomes difficult, and the weight of the composite material increases, which is not preferable. On the other hand, when the component C is less than 0.5 parts by weight, the effect of the amine compound as an expelling agent is small, resulting in poor curing or a very slow curing rate, which is not preferable. On the other hand, when the amount exceeds 20 parts by weight, an unnecessary component for curing is increased, and the physical properties of the composite material are deteriorated.

  The manufacturing method of the fiber reinforced prepreg blended with the above epoxy resin composition for low temperature curable prepreg may be a general method, and specifically, there are a hot melt method and a solvent method, but there is no particular limitation. However, in particular, care must be taken not to remove or destroy the B component organic polymer film during manufacture. If it is removed or destroyed, the amine compound is desorbed from the clathrate compound, and the amine compound immediately reacts with the epoxy resin compound, resulting in poor storage stability. These can be achieved by appropriately considering the temperature and pressure at the time of resin impregnation, or the type of solvent when a solvent is used. Further, the blending amount of the low-temperature curing type epoxy resin composition composed of the components A, B and C to be impregnated into the reinforcing fiber is preferably in the range of about 20 to 70% by weight in the obtained prepreg.

  Next, a room temperature curing method at the time of molding the prepreg impregnated with the above-described epoxy resin will be described. In forming a fiber-reinforced prepreg, it is necessary to first attach and press the prepreg on the surface to be bonded so as not to collect air. Next, in the present invention, by heating the prepreg for a short time at a low temperature, the organic high molecular weight film of the inclusion compound is removed or destroyed, and the amine compound in the B component is removed from the inclusion compound by the C component expelling agent. It is driven out and reacts with the A component epoxy compound to cure. In this case, the heating temperature is preferably equal to or higher than the melting point or softening point (40 to 100 ° C.) of the coated organic polymer.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. The evaluation methods in Examples and Comparative Examples of the present invention are as follows: Storage stability: 15 ° C., prepreg tactile evaluation after standing for 1 month ○: Good Δ: Slightly good (Slightly cured) However, there is no hindrance to use)
× ... defect (cannot be used after curing)
・ Attachment workability: Workability / safety and hygiene when a prepreg or sheet is applied to a cement surface that has been treated with an epoxy primer; After standing at room temperature (25 ° C.) for 1 week, it is immersed in acetone for good evaluation of the cured state.
Defective ... The surface swells or (partially) dissolves and is poorly cured.
・ Surface condition after curing; surface condition when visually observed after curing ○ ・ ・ ・ Good, △ ・ ・ ・ Slightly good, × ・ ・ ・ Defective

Example 1
An PAN-based carbon fiber (strength: 350 kg / mm ² , tensile elastic modulus: 24 t / mm ² ) aligned in one direction is impregnated with an epoxy resin composition prepared with the following components A, B, and C to obtain carbon fiber A prepreg having a basis weight of 150 g / m ² , a resin content of 43 wt%, and sandwiched between a polyethylene film and a release paper on both sides was produced. As shown in Table 1, this prepreg had good storage stability. Next, the polyethylene film of the prepreg was peeled off, and affixed to the cemented surface subjected to the epoxy primer treatment while removing voids from the release paper using a pressure roller that was slowly heated to about 90 ° C. After cooling, the release paper was peeled off. This operation was not particularly troublesome, and there was no problem in terms of safety and health, such as odor. Further, after 1 week, the resin was cured at room temperature without heating, and the curing characteristics and the surface condition after curing were good.
• A component: 100 parts by weight of an epoxy compound (7: 3 mixture of Epicoat 828 and Epicoat 1001: Oily Shell Epoxy Co., Ltd.) • B component: 5 paraffin wax (Japan Petroleum Corporation) having a melting point of 60 ° C. Powdered molecular sieve 5A coated with 15% by weight and adsorbed 15% by weight of ethylenediamine (average particle size 4 μm, pore size 5 mm: manufactured by Union Showa Co., Ltd.) 36 parts by weight / C component; ethylene glycol 2% by weight

Example 2
An epoxy resin composition prepared with the following components A, B, and C is impregnated into pitch-based carbon fibers (strength 370 kg / mm ² , tensile elastic modulus 40 t / mm ² ) aligned in one direction, and carbon fibers A prepreg having a basis weight of 100 g / m ² , a resin content of 45 wt%, and both sides sandwiched with a polyethylene film and release paper was produced. When this prepreg was evaluated in the same manner as in Example 1, as shown in Table 1 , the storage stability, application workability, safety and hygiene, curing characteristics, and surface condition after curing were good.
・ A component: 100 weight of epoxy compound (7: 3 mixture of Epicoat 828 and Epicoat 1001: made by Yuka Shell Epoxy Co., Ltd.) ・ B component: 7 weight of paraffin wax (Japan Petroleum Corporation) with a melting point of 80 ° C. Powdery diatomaceous earth coated with 20% by weight of triethylenetetramine (Chrisvar PW-20: average particle size of about 6 μm, pore size of 30 to 200 mm: manufactured by Nittetsu Mining Co., Ltd.) 50 parts by weight / C component Glycerin 3% by weight

Comparative Example 1
An epoxy resin composition prepared with the following components A and B is impregnated into a PAN-based carbon fiber (strength: 350 kg / mm ² , tensile elastic modulus: 24 t / mm ² ) aligned in one direction, and the carbon fiber basis weight is 150 g. / m ^2, resin content 48 wt%, to prepare a sandwich prepreg on both sides with polyethylene film and release paper. This prepreg had good storage stability. When this prepreg was evaluated in the same manner as in Example 3, as shown in Table 2, the workability of attaching was not particularly troublesome, and there was no problem in terms of safety and health such as odor. However, even after 3 weeks, it was uncured at room temperature.
・ A component: 100 parts by weight of epoxy compound (7: 3 mixture of Epicoat 828 and Epicoat 1001: made by Yuka Shell Epoxy Co., Ltd.) ・ B component: Powdered molecular sieve 5A adsorbed with 15% by weight of ethylenediamine ( Average particle size 4 μm, pore size 5 mm: Union Showa Co., Ltd.) 36 parts by weight

Comparative Example 2
PAN-based carbon fiber (strength 350 kg / mm ² , tensile elastic modulus 24 t / mm ²⁾ aligned in one direction with the epoxy resin composition prepared with the A and C components used in Example 1 and the following B component. ), And a prepreg having a carbon fiber basis weight of 150 g / m ² , a resin content of 48 wt%, and sandwiched between a polyethylene film and a release paper on both sides was produced. As shown in Table 1, this prepreg was very poor in storage stability and was cured after one week, so that the prepreg could not be attached to cement.
-A component: 100 parts by weight-B component: 36 parts by weight of molecular sieves 5A adsorbed with 15% by weight of ethylenediamine-C component: 2 parts by weight of ethylene glycol

Comparative Example 3
After uniformly applying the following D component to a cement surface that has been treated with an epoxy primer to a thickness of about 0.5 mm using a brush, a 120 ° C. type pitch-type carbon fiber prepreg (fiber: strength 370 kg / mm) ² and a tensile elastic modulus of 40 t / mm ² , a carbon fiber basis weight of 100 g / m ² , and a resin content of 33 wt%) were attached, and the same evaluation as in Example 1 was performed. As shown in Table 1, this prepreg had good storage stability, and there was no particular problem in sticking workability. However, since toluene was used, there was a problem in terms of safety and hygiene due to the strong odor. The composite material was considerably uncured after one week, and voids were observed on the surface.
D component: Toluene solution containing 80% by weight of 100: 7 mixture of epoxy compound (Epicoat 828) and ethylenediamine

Claims (2)

An epoxy resin composition for a low-temperature curable prepreg comprising the following components A, B and C as essential components.
A: Epoxy compound B having at least two or more glycidyl groups in one molecule; Adsorbs amine compounds having active hydrogen, and has a high melting point or softening point of 40-100 ° C. Inclusion compound C coated with molecules; a compound that can serve as a displacer of amine compounds for inclusion compound B component A low-temperature curable prepreg, wherein a fiber is impregnated with the epoxy resin composition according to claim 1.