JPH069758A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin compsn. which is excellent in handling properties and in storage stability at room temp. and cures at a low temp. by compounding an epoxy resin with a thermoplastic resin sol. therein and a latent curing agent of a thermal curing type which is activated at a specified low temp. CONSTITUTION:The resin compsn. is obtd. by compounding 100 pts.wt. epoxy resin with 1-30 pts.wt. thermoplastic resin sol. in the epoxy resin and 3-40 pts.wt. latent curing agent of a thermal curing type which is activated at 70-90 deg.C. The compsn. is stable at room temp. at least for 20 days, a practically enough time, cures at 70-90 deg.C to such an extent as to exhibit satisfactory characteristics, is free from resin flow during molding, has a suitable tackiness, and gives a sheet having freely controllable drape properties.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to epoxy resin compositions which cure at relatively low temperatures.

[0002]

2. Description of the Related Art Epoxy resins are used in a wide range of fields because they have excellent mechanical and electrical properties after curing. For example, it is widely used as a sealant for electronic materials, paints / paving materials, and adhesives. Further, in recent years, it has come to be used as a matrix resin for a fiber composite material because of its excellent mechanical properties and heat resistance, and is widely used from aircraft applications to general-purpose applications such as fishing rods and golf club shafts.

The properties required of such an epoxy resin are not only excellent in mechanical properties after curing, but also long-term stability at room temperature, handleability [low flow (flowability), moderate tack (adhesiveness), It is required to have an appropriate drape property (flexibility) when formed into a sheet. Further, there is an increasing demand for low temperature curing or short time curing in order to shorten the molding cycle and reduce the energy cost.

In response to such demands, the temperature is from room temperature to 80 to 9
There are already some resins that cure at low temperatures of 0 ° C. However, most of these are so-called two-component resin compositions in which the main component and the curing agent are mixed immediately before curing, the stability at room temperature after mixing the two components is poor, and even if the pot life is long, it is several hours. Is the order. In addition, the resin viscosity immediately after mixing is low, resulting in poor handleability and working environment. Further, as a one-component epoxy resin composition, for example, JP-A-61-436
Japanese Unexamined Patent Publication No. 16 discloses a combination of an epoxy resin, a dibasic acid dihydrazide compound, a urea compound and an alcohol-based or phenol-based compound having a melting point of 50 ° C. or higher. These epoxy resin compounds have stability at 30 ° C. for 14 days or more, but require relatively high temperature and long time curing conditions of 100 ° C. for 2 hours, and are practically used at 90 ° C. or lower because of insufficient curing. It is not possible. Further, JP-A No. 1-129084 discloses a resin adhesive comprising an epoxy resin, a reaction product of bisphenol A and a monoglycidyl ether of bisphenol A, and an imidazole compound which is a curing agent and a curing accelerator. . This resin composition also requires a high temperature of 96 hours for 2 hours and a long time, and the CFRP characteristics of using this resin composition as a matrix resin are unidirectional CFRP 0 ° bending strength FS // = 1.27 GPa, FM // = 117 GP
a, ILSS = 76 MPa, which is lower than the CFRP characteristics generally used for general-purpose applications of current 120 ° C. curing. Further, this resin composition has a large increase in viscosity at the time of resin preparation, and it is difficult to form a hot melt film.

In addition to these, a resin composition using P-hydroxystyrene (Japanese Patent Publication No. 32-18551, US Pat. No. 3,884,992), or a resin composition using a boron trifluoride complex (Europe) Patent publication No. 165,23
No. 0) and the like have been reported, but none of them has a resin composition which satisfies the requirements sufficiently because the stability at room temperature is poor and the curing requires a high temperature and a long time.

Further, there is a great demand for excellent handleability, and in particular, when used as a matrix resin of a composite material, special demands are often made for tackiness when formed into a sheet. Up to now, there have been reported methods to control the tack and drape when forming a sheet according to the specifications, or the resin flow during molding, but generally improving the handleability affects the curing characteristics. Give,
It was difficult to obtain a completely cured product by low temperature curing.

In other words, a low temperature curable resin which is stable in storage at room temperature and whose handleability can be controlled according to its specifications has been desired, but no technique satisfying all of them has been developed by the conventional techniques. .

[0008]

DISCLOSURE OF THE INVENTION The present invention has a stability of 20 days or more at room temperature, which is sufficient for practical use.
A resin composition that cures at a temperature of up to 90 ° C. until it has practically sufficient properties, further suppresses the resin flow during molding, and has an appropriate tack and the drape property when formed into a sheet can be freely controlled. With the goal.

[0009]

The present invention comprises: (a) epoxy resin: 100 parts by weight (b) thermoplastic resin soluble in epoxy resin: 1
˜30 parts by weight (c) Heat-curable latent curing agent that is activated at 70 to 90 ° C .: 3 to 40 parts by weight, shows excellent storage stability at room temperature, and is cured at low temperature, and further resin flow The epoxy resin composition of the present invention has excellent handleability in which the resin viscosity, which is a factor governing tackiness and drapability, can be controlled according to requirements, and the epoxy resin composition according to the present invention is 2 to 6 at 70 to 90 ° C. It has a sufficient storage stability such that it cures to a practically sufficient extent within 120 minutes at 120 to 140 ° C. and has a 25 ° C. prepreg life of 20 days or more.

The epoxy resin which is the component (a) used in the present invention is not particularly limited, and a bisphenol A type epoxy resin, a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, or a glycidyl amine type epoxy resin is used. Can be mentioned. Among these, it is preferable to use a bisphenol A type epoxy resin that is well balanced in terms of handleability, CFRP characteristics to be obtained, and economy. Of course, in order to have various properties, it is possible to mix and use several kinds of epoxy resins, and it is also possible to use a product obtained by reacting the epoxy resin with an amine compound or an acid anhydride within a range not gelling. It is a more preferred embodiment of the present invention.

The epoxy-soluble thermoplastic resin as the component (b) plays a role in controlling handleability in the present invention. In other words, it does not affect the curing characteristics so much,
By adjusting the viscosity of the epoxy resin composition, it is possible to suppress the flow and to impart appropriate tackiness and drape property when formed into a sheet. However, the addition amount is preferably 1 to 30 parts. When 30 parts or more of such an additive is added, the reactivity is lowered, and when it is cured at a low temperature, the curing becomes insufficient and it is very difficult to obtain a molded product having mechanical strength, etc. If it is less, the expected viscosity adjusting effect cannot be obtained.

Examples of the component (b) epoxy-soluble thermoplastic resin include polyvinyl butyral, polyvinyl formal, polyether sulfone, polysulfone, polyarylate, and the like, but are not limited thereto. Among them, polyvinyl butyral, polyvinyl formal, and polyether sulfone are highly effective and particularly desirable.

The component (c), which is a thermosetting latent curing agent that is activated at 70 to 90 ° C., is, for example, an amine adduct type curing agent (commercially available from Ajinomoto Co., Inc. under the trademark "Amicure") and microcapsules. Type curing agents [commercially available from Asahi Kasei Kogyo Co., Ltd. under the trademark "Novacure"], etc., and even when these curing agents are mixed with an epoxy resin, they are relatively stable and hardly react at room temperature to 50 ° C. 70-90 ° C
It is a so-called thermosetting latent curing agent that is activated and starts the reaction. These latent curing agents may be used alone, or these latent curing agents may be used in combination with curing agents such as urea compounds, cyano compounds, dihydrazide compounds and acid anhydrides. When used in combination with other curing agents, the reactivity at low temperatures is lowered, but the storage stability at room temperature to around 50 ° C. is improved, so it is advisable to mix them appropriately according to the purpose. In any case, the addition amount of these latent curing agents is appropriately 3 to 40 parts.
If it is less than 40 parts, curing will be insufficient, and if it exceeds 40 parts, the stability at room temperature will be deteriorated, which is not preferable.

The method for preparing the epoxy resin composition of the present invention is not particularly limited, but component (c) is activated at a relatively low temperature and the reaction starts, so it is not preferable to mix all of them at once. This is because the thermoplastic resin of component (b) is generally difficult to dissolve in the epoxy resin of component (a) and must be dissolved at high temperature, for a long time with stirring, or by adding a solvent. This is because the stability may be reduced and the influence of the component (c) itself due to the solvent may be considered. Therefore, it is preferable that the component (b) is first uniformly dissolved in the component (a). At that time, when heated, it is sufficiently cooled before adding the component (c), and when a solvent is added, the solvent is completely removed.

The use of the epoxy resin composition according to the present invention is not particularly limited, and it can be used anywhere as long as the characteristics of the present epoxy resin composition can be utilized, but it is particularly suitable as a matrix resin for prepreg. Is. If it is used as a matrix resin for prepreg, it can be molded at a low temperature, a flow at the time of molding can be suppressed, and a prepreg whose tackiness and drapeability can be controlled according to requirements can be provided. Moreover, if it is made into a film and the flow is set to a low value, it can be used as a sheet adhesive.
Further, a microballoon or a low-temperature foaming agent may be added as an additive to be used as a lightweight auxiliary material for low-temperature curing.

The resin composition of the present invention cures at a low temperature of 70 to 90 ° C. for 2 to 6 hours to a practically sufficient degree, and further 1
At a temperature of 20 to 140 ° C., it cures in a short time of 30 minutes or less. Moreover, it has a life of 20 days or more at 40 ° C, and the viscosity level can be freely controlled, which is economical and economical.
Also, it has a great feature in comparison with the conventional low temperature curable epoxy resin composition even in the problem of working environment which has been particularly problematic in recent years. Therefore, it is expected to be used in fields that have not been used so far because of problems of curing conditions, room temperature stability, or working environment.

[0017]

The present invention will be described in more detail with reference to the following examples.

Abbreviations of compounds in Examples and test methods are as follows.

The curing conditions were 80 ° C. × 3 hours in all of the examples and comparative examples.

Ep828: Bisphenol A type epoxy resin (oiled shell) Ep1009: PVF: Polyvinyl formal Denkaformal # 200 (manufactured by Denka) PVB: Polyvinyl butyral Denkabutyral # 4000-1 (manufactured by Denka) PES: VICTREX PES 5003P (manufactured by ICI) DCMU: 3,4-dichlorophenyl-N, N-dimethylurea PMU: phenyl-N, N-dimethylurea MY-24: amine adduct type latent curing agent Amicure (manufactured by Ajinomoto Co., Inc.) ) PN-23: 〃 HX-37211: Microcapsule type latent curing agent Novacure (manufactured by Asahi Kasei Co., Ltd.) <Bending test (3-point bending)> Equipment: Orientec Co., Ltd. Tensilon sample shape: 60 mm ^I × 8 mm ^W × 2 mm ^t Span length: 32mm Indenter tip Radius: 3.2mm CROSS HEAD SPEED: 2mm / min <Viscosity Measurement> Apparatus: Rheometrics Inc. RDA-700 Measurement conditions: Disk Plate 12.5mmφ Rate 10 rad / sec Strain 100% Temp. 40 ° C, 50 ° C <Life measurement> Put the prepared resin in a high temperature dryer at 40 ° C to add heat history.

The viscosity of the resin after 40 days at 40 ° C. was measured by the above-mentioned viscosity measuring method, and X at which the viscosity was twice the viscosity on day 0 was defined as the life.

Example 1 With the composition shown in Table 1, first, Ep828 of the component (a) was mixed with PVF of the component (b) at 160 ° C.
Dissolve in 3 hours, cool to room temperature and then at room temperature, component (c)
MY-24 was added and mixed uniformly. The life of the resin composition thus obtained at 40 ° C and the viscosity at 50 ° C were measured. In addition, each resin composition has a thickness of 2 mm.
The Teflon plate was used as a spacer, sandwiched between glass plates and cured under predetermined curing conditions. A bending test of the obtained epoxy resin cured product was performed, and the results are also shown in Table 1.

<Examples 2 and 3> Resins were prepared in the same manner as in Example 1 except that the amount of PVF as the component (b) was changed as shown in Table 1, and the same tests were conducted. The results are also shown in Table 1.

<Example 4> PVB as the component (b) was used as PVB.
In the same manner as in Example 1 except that the component (b) was first dissolved in the component (a) at 160 ° C for 3 hours, cooled to room temperature, and then the component (c) was added at room temperature. Uniformly mixed. The same test as in Example 1 was performed on the obtained resin composition. The results are also shown in Table 1.

<Example 5> PVF of the component (b) was added to PES.
In the same manner as in Example 1 except that the amount of the component (b) was changed to 5 parts, the component (b) was first dissolved in the component (a) at 160 ° C. for 3 hours, cooled to room temperature, and then cooled to room temperature. Was added and mixed uniformly. The same test as in Example 1 was performed on the obtained resin composition. The results are also shown in Table 1.

<Examples 6 and 7> MY-24 of component (c)
In the same manner as in Example 1 except that the components are changed as shown in Table 1, and the component (b) is first added to the component (a) at 160 ° C.
Dissolve in 3 hours, cool to room temperature and then at room temperature, component (c)
Was added and mixed uniformly. The same test as in Example 1 was performed on the obtained resin composition. The results are also shown in Table 1.

<Examples 8 and 9> MY-24 as component (c)
The same procedure as in Example 1 was carried out except that DCMU and PMU were used alone as shown in Table 1, and the preparation method was likewise such that the component (b) was first dissolved in the component (a) at 160 ° C for 3 hours and cooled to room temperature. After that, the components (c) were added together at room temperature and mixed uniformly. The same test as in Example 1 was performed on the obtained resin composition. The results are also shown in Table 1.

<Comparative Example 1> The procedure of Example 1 was repeated except that the component (b) was not used, and the preparation method was to uniformly mix the components (a) and (c) at room temperature. The same test as in Example 1 was performed on the obtained resin composition. The results are shown together in Table 1. It is expected that the viscosity is extremely low and the resin flow is large as compared with Example 1.

<Comparative Example 2> Ep of high viscosity for controlling viscosity
1009 is used in combination with Ep828 as shown in Table 1 and component (b)
Example 1 was repeated, except that the
p1009 was dissolved in Ep828 at 160 ° C. for 1 hour,
After cooling to room temperature, the component (c) was added at room temperature and mixed uniformly. The same test as in Example 1 was performed on the obtained resin composition. The results are also shown in Table 1. A clear decrease in physical properties was observed.

Comparative Example 3 The same procedure as in Example 6 was carried out except that the component (b) was not used, and the preparation method was to uniformly mix the two components (a) and (c) at room temperature. The same test as in Example 1 was performed on the obtained resin composition. The results are also shown in Table 1. It is expected that the viscosity is low and the resin flow is large as compared with Example 6.

<Comparative Examples 4 and 5> Resins were prepared in the same manner as in Example 1 except that the amount of PVF as the component (b) was changed as shown in Table 1, and the same tests were conducted. The results are shown together in Table 1. It can be seen that the physical properties of the cured products are extremely lower than those of Examples 2 and 3.

As is clear from Table 1, the epoxy resin composition obtained from the present invention exhibits excellent physical properties when cured at low temperatures, has excellent stability at low temperatures, and controls the viscosity of the uncured resin within a considerable range. I know that I can do it.

<Examples 10 to 14> The same resin composition as in Example 1 was used to cure under the curing conditions shown in Table 2, and the resulting cured product was subjected to a bending test. The results are shown together in Table 2. As is clear from Table 2, the epoxy resin composition of the present invention is sufficiently cured at a low temperature of 70 to 90 ° C, and sufficiently cured at 120 to 140 ° C in 30 minutes or less.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

The resin composition of the present invention is 70 to 90 ° C.
It is cured at a low temperature of 2 to 6 hours to a practically sufficient degree, and at a temperature of 120 to 140 ° C., it is cured in a short time of 30 minutes or less. Moreover, it has a life of at least 40 days at 40 ° C, and the viscosity level can be freely controlled.

Therefore, the resin composition of the present invention has a great advantage as compared with the conventional low temperature curing epoxy resin composition in terms of production, economy, or the problem of working environment which has been particularly problematic in recent years. Therefore, it is expected to be used in fields that have not been used so far because of problems of curing conditions, room temperature stability, or working environment.

Claims (6)

[Claims] 1. (a) Epoxy resin: 100 parts by weight (b) Thermoplastic resin soluble in epoxy resin: 1
-30 parts by weight (c) A heat-curable latent curing agent that is activated at 70 to 90 ° C: 3 to 40 parts by weight. 2. The epoxy resin composition according to claim 1, wherein the thermoplastic resin as the component (b) is polyvinyl formal. 3. The epoxy resin composition according to claim 1, wherein the thermoplastic resin as the component (b) is polyvinyl butyral. 4. The epoxy resin composition according to claim 1, wherein the thermoplastic resin as the component (b) is polyether sulfone. 5. The epoxy resin composition according to claim 1, wherein the latent curing agent as the component (c) is an amine adduct type latent curing agent. 6. The epoxy resin composition according to claim 1, wherein the latent curing agent as the component (c) is a microcapsule type latent curing agent.