JP2006028375A - Epoxy resin composition, prepreg, molded article and method for producing epoxy resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition having easily controllable viscosity, a prepreg having excellent handleability, a molded article molded by the thermal curing of the prepreg and a method for producing the epoxy resin composition. <P>SOLUTION: The epoxy resin composition is produced by reacting an epoxy resin with the 1st curing agent for curing the epoxy resin. The epoxy resin has an epoxy equivalent of ≤250 g/eq and viscosity of ≤300 poise at 25°C in uncured state, and the 1st curing agent is an aromatic amine. The invention further provides a prepreg produced by using the epoxy resin composition and a molded article produced by using the prepreg. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an epoxy resin composition with easy viscosity control, a prepreg excellent in handling properties, a molded article formed by heating and curing the prepreg, and a method for producing the epoxy resin composition.

  Epoxy resins exist from low-viscosity types to high-viscosity types depending on their molecular weights, so that paints and structural adhesives can be used as epoxy resin compositions to which specific curing agents and fillers are added depending on the purpose. It is widely used as a raw material for manufacturing printed circuit boards and composites. One such application is prepreg manufacturing. In general, “prepreg” is a state in which glass cloth or carbon fiber is impregnated with a thermosetting resin such as an epoxy resin composition and dried by heating to a stable state that can be stored (B stage). Say things.

  However, when the epoxy resin is of a low-viscosity type, it is difficult to hold the desired resin amount on the prepreg substrate; even if the resin can be held on the substrate, the heat drying step After that, the tackiness (stickiness) is excessively generated on the surface of the prepreg, the handling property of the prepreg is deteriorated, and it becomes difficult to form a uniform resin layer. However, there is a problem that a completely molded state (C stage) is reached without passing through the prepreg (B stage) stage, and a desired molded product cannot be obtained.

  In order to improve the above problem, a method has been proposed in which an epoxy resin composition comprising a low-viscosity type and a high-viscosity type is prepared, and the shortcomings of the low-viscosity type epoxy resin are compensated with the high-viscosity type epoxy resin. However, even when such an epoxy resin composition is used, when the filler is added to the epoxy resin composition, the dispersibility of the filler is lower than when only the low viscosity type epoxy resin is used; Although it is necessary to adjust the viscosity of the resin composition with a high-viscosity type epoxy resin, this limits the range of properties of the molded product;

JP-A-7-316260 discloses an epoxy resin composition containing a pre-react reaction product and a main agent (Patent Document 1). That is, a pre-react reaction product is prepared by heating and drying a master batch composed of an epoxy resin, a solvent having a boiling point of 30 to 130 ° C., a curing agent and a curing accelerator at 60 to 120 ° C. for 10 to 180 minutes. An epoxy resin composition is disclosed in which a laminate having excellent heat resistance is obtained by reacting a pre-reacted product with a main agent containing another type of epoxy resin.
JP 7-316260 A

  However, the conventional epoxy resin composition still has room for improvement in terms of dispersibility, solubility when it is mixed with fillers and other additives, and handling properties when it is made into a prepreg. Accordingly, an object of the present invention is to provide an epoxy resin composition with easy viscosity control, a prepreg excellent in handling properties, a molded article formed by heat-curing the prepreg, and a method for producing the epoxy resin composition. To do.

  In order to solve the above problems, the present invention is an epoxy resin composition obtained by reacting an epoxy resin with a first curing agent for curing the epoxy resin, and the epoxy resin has an epoxy equivalent of 250 g / The epoxy resin composition is provided with an eq or lower, a viscosity at 25 ° C. before curing of 300 poise or lower, and the first curing agent being an aromatic amine.

  The epoxy resin composition according to the present invention is excellent in dispersibility and solubility when an additive such as a filler is added because viscosity adjustment is easy. The viscosity adjustment can be performed while maintaining the dispersion state of the filler or the like.

  Here, “epoxy equivalent” refers to a value obtained by dividing the average molecular weight by the number of epoxy groups per molecule in terms of the mass per epoxy group (g / eqiv.).

  Preferred embodiments of the invention are as follows. When the compounding amount of the epoxy resin for preparing the epoxy resin composition is a standard (100 parts by weight), the compounding amount of the first curing agent is preferably 1 to 10 parts by weight.

The viscosity at 25 ° C. of the epoxy resin composition is preferably 1000 poise or more, and the viscosity at 70 ° C. is preferably 200 poise or less.

  Moreover, it is preferable that the number of the amine functional groups of the said aromatic amine is 2-7, and it is preferable that the said amine functional group is a primary amine. The aromatic amine is preferably diaminodiphenylmethane and / or a derivative thereof.

  Moreover, it is preferable that the said epoxy resin composition contains the 2nd hardening | curing agent which further hardens the epoxy resin in the said epoxy resin composition. The blending amount of the second curing agent is preferably 3 to 50 parts by weight, based on the blending amount of the epoxy resin for preparing the epoxy resin composition (100 parts by weight).

  The present invention also provides a prepreg obtained by impregnating a base material with the above epoxy resin composition. The prepreg has excellent handling properties because it can control tackiness.

  The present invention further provides a molded body obtained by molding the prepreg by heat curing. The said molded object is equipped with the physical property equivalent to the case where a molded object is manufactured using the conventional epoxy resin composition which consists of a low-viscosity type and a high-viscosity type, maintaining the dispersibility of additives, such as a filler. .

  The present invention is a method for producing an epoxy resin composition comprising a step of reacting an epoxy resin with a first curing agent, wherein the epoxy resin has an epoxy equivalent of 250 g / eq or less and is cured. It provides a method for producing an epoxy resin composition, wherein the previous viscosity at 25 ° C. is 300 poise or less, and the first curing agent is an aromatic amine.

  According to the method for producing an epoxy resin composition according to the invention, it is possible to produce an epoxy resin composition that is easily adjusted in viscosity and excellent in dispersibility when an additive such as a filler is added. .

  Preferred embodiments of the invention are as follows. The reaction between the epoxy resin and the first curing agent is preferably performed at 100 to 140 ° C. for 30 to 240 minutes.

  Furthermore, it is preferable to include a step of adding a second curing agent to the epoxy resin composition.

  ADVANTAGE OF THE INVENTION According to this invention, the epoxy resin composition with easy viscosity control, the prepreg excellent in handling property, and the molded object shape | molded by heat-hardening this prepreg are provided. Moreover, according to this invention, the manufacturing method of the epoxy resin composition with which viscosity adjustment is easy and the dispersibility of an additive is favorable is provided.

  As described above, the epoxy resin composition of the present invention is an epoxy resin composition obtained by reacting an epoxy resin with a first curing agent that cures the epoxy resin, and the epoxy resin has an epoxy equivalent thereof. Is 250 g / eq or less, the viscosity at 25 ° C. before curing is 300 poise or less, and the first curing agent is an aromatic amine.

  The epoxy resin has an epoxy equivalent of 250 g / eq or less and a viscosity at 25 ° C. before curing of 300 poise or less when measured using a dynamic viscoelasticity measuring instrument (TA instruments Japan). If there is no particular limitation, the type is not particularly limited, and examples thereof include bisphenol type epoxy resins such as bisphenol A type and bisphenol F type. These may be used alone or in combination.

  When the epoxy equivalent of the epoxy resin exceeds 250 g / eq, it is not preferable because it is semi-solid or solid at room temperature. Moreover, when the viscosity at 25 ° C. before curing of the epoxy resin exceeds 300 poise, the dispersibility of the filler such as filler is lowered, which is not preferable.

  The aromatic amine as the first curing agent preferably has 2 or more amine functional groups. However, if the number of amine functional groups is too large, unreacted functional groups are sterically hindered, leaving unreacted functional groups, which may result in a decrease in the physical properties of the cured product. It is preferable that it is 7 or less. Further, the amine functional group is preferably a primary amine having a low reaction energy from the viewpoint of reacting the structure of the reaction product in a linear form. Specific examples include diaminodiphenylmethane represented by the following formula (1) and / or a diaminodiphenylmethane derivative represented by the following formula (2).

（上記式中、ｎは１〜５の整数を示す）

(In the above formula, n represents an integer of 1 to 5)

  The diaminodiphenylmethane derivative is preferably n = 1. When the diaminodiphenylmethane derivative with n = 1 is 50% or more, the diaminodiphenylmethane derivative with n = 0, 2, 3, 4, 5,. It may be included.

  The compounding amount of the aromatic amine in the epoxy resin composition is 1 to 10 parts by weight, more preferably 3 to 7 parts by weight, based on the compounding amount of the epoxy resin (100 parts by weight).

  The epoxy resin composition can be obtained by reacting the epoxy resin with an aromatic amine as a first curing agent. This epoxy resin composition has a viscosity at 25 ° C. of 1000 poise or more and a viscosity at 70 ° C. of 200 poise or less when measured using a dynamic viscoelasticity measuring device (TA instruments Japan). It is preferable. By appropriately adjusting the viscosity according to the temperature, various additives described later can be dispersed in the epoxy resin as necessary, and the added value of the epoxy resin composition can be increased. Moreover, the 2nd hardening | curing agent and hardening accelerator which are mentioned later can also be disperse | distributed efficiently. In addition, the viscosity of an epoxy resin composition can be suitably adjusted in said range according to the compounding quantity of a said 1st hardening | curing agent.

  The epoxy resin composition preferably includes a second curing agent that further cures the epoxy resin in the epoxy resin composition. The second curing agent is not particularly limited as long as it is used as a curing agent for the above-described epoxy resin. For example, diaminodiphenylmethane (DDM), diaminodiphenylsulfone (DDS), diaminodiphenyl ether (DDE), Imidazoles, hexamethylenediamine, polyamidoamine, dicyandiamide (DICY), phenol novolac, and the like can be used.

  The amount of the second curing agent in the epoxy resin composition is appropriately changed according to the type of the curing agent to be used, but generally, when the amount of the epoxy resin is used as a reference (100 parts by weight). The amount is preferably 3 to 50 parts by weight. Specifically, for example, when using dicyandiamide (DICY), it is 3 to 7 parts by weight, and when using diaminodiphenylsulfone (DDS), it is 20 to 40 parts by weight.

  Moreover, it is preferable from a viewpoint of acceleration | stimulation of hardening reaction to use a hardening accelerator together with the said hardening | curing agent. As the curing accelerator, known curing accelerators such as imidazole compounds, urea compounds, tertiary amines, and boron trifluoride complex salts can be used.

  The blending amount of the curing accelerator is preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on the blending amount of the epoxy resin (100 parts by weight).

The epoxy resin composition according to the present invention includes various additives such as other synthetic resins, carbon nanotubes, Fe powder, Fe ₂ O ₃ , mica, and the like, as long as various properties are not deteriorated. A filler such as silica, a polyester resin, an antioxidant, a surfactant, a coupling agent and the like may be added.

  The method for producing an epoxy resin composition according to the present invention comprises a step of obtaining an epoxy resin composition by reacting an epoxy resin with a first curing agent, and reacting the epoxy resin composition with a second curing agent. The epoxy resin has an epoxy equivalent of 250 g / eq or less, a viscosity at 25 ° C. before curing of 300 poise or less, and the first curing agent is an aromatic amine. is there.

  The details of the epoxy resin and the aromatic amine are the same as those of the epoxy resin and the aromatic amine blended in the epoxy resin composition described above, and thus the description thereof is omitted here.

  In the step of obtaining the epoxy resin composition, the epoxy resin and the aromatic amine are preferably reacted at 100 to 140 ° C. for 30 to 240 minutes. By adjusting the reaction time within such a range, the molecular weight of the resin composition can be appropriately adjusted.

  The epoxy resin composition thus obtained has a viscosity at 25 ° C. of not less than 1000 poise and a viscosity at 70 ° C. when measured using a dynamic viscoelasticity measuring instrument (TA instruments Japan). Is preferably 200 poises or less. By appropriately adjusting the viscosity within this range, the dispersibility of the additive in the epoxy resin can be improved. Moreover, the 2nd hardening | curing agent and hardening accelerator which are mentioned later can also be disperse | distributed efficiently. In addition, the viscosity of an epoxy resin composition can be suitably adjusted in said range according to the compounding quantity of a said 1st hardening | curing agent.

  The step of reacting the epoxy resin composition with the second curing agent is appropriately changed according to the type of the curing agent to be used, but is generally performed at 110 to 180 ° C. for 60 to 300 minutes. Is preferred. Specifically, for example, when dicyandiamide (DICY) is used as the second curing agent, it is preferably performed at 120 to 140 ° C. for 60 to 180 minutes, and diaminodiphenylmethane (DDM) and diaminodiphenylsulfone (DDS) are used. When it is, it is preferable to carry out at 150-180 degreeC for 60-180 minutes.

  Furthermore, it is preferable that the manufacturing method of the epoxy resin composition of the said invention is equipped with the process of adding a hardening accelerator. The curing accelerator may be added alone or together with the second curing agent.

  The epoxy resin composition thus obtained can be used as a raw material for prepreg production. That is, a prepreg in a semi-cured state (B stage) can be produced by impregnating a base material with the epoxy resin composition according to the present invention by a predetermined method and drying by heating at a predetermined temperature and pressure.

  The base material of the prepreg is appropriately selected according to the purpose. For example, glass cloth, carbon fiber, aramid fiber, polyester fiber, or the like can be used. In addition, as a method of impregnating the base material with the epoxy resin composition according to the present invention, a laminating method in which the base material is impregnated while thermally laminating (heating and melting) the epoxy resin composition formed in a film form, or a liquid epoxy A dipping method in which the resin composition is diluted with a solvent and impregnated with the resin composition, followed by heat drying can be used. The prepreg thus obtained has a reduced tackiness and an excellent handling property.

  Furthermore, a molded body in a completely cured state (C stage) can be manufactured by heat curing the obtained prepreg at a predetermined temperature and pressure. Manufacture of a molded object can be performed using a well-known method.

  Diaminodiphenylmethane (MDA-150) as a first curing agent was added to 100 parts by weight of bisphenol A type epoxy resin (Epicoat 827, epoxy equivalent of 180 to 190, viscosity at 25 ° C. of 90 to 110 poise, manufactured by JER) as an epoxy resin. 5 parts by weight of Mitsui Takeda Chemical Co., Ltd.) was added and mixed, and reacted at 120 ° C. for 120 minutes to obtain an epoxy resin composition. Table 1 also shows the weight average molecular weight and the molecular weight distribution of the epoxy resin composition obtained by changing the reaction time. The molecular weight distribution was measured by GPC (gel permeation chromatography).

[Test Example 1] Measurement of viscosity of epoxy resin composition Using the epoxy resin composition obtained in Example 1, the viscosity of each epoxy resin composition was measured in the following manner. That is, the epoxy resin composition is heated at 120 ° C. for 120 minutes and then cooled to 25 ° C., and the sample is placed in a dedicated container of a dynamic viscoelasticity measuring machine (TA instruments Japan). did. And the viscosity of the epoxy resin composition in each temperature of 25 degreeC, 50 degreeC, 58 degreeC, and 70 degreeC was measured on conditions with a frequency of 1 Hz and a temperature increase rate of 5 degree-C / min. The results are shown in Table 2.

  As a control, an epoxy resin composition having the following composition was prepared in the same manner as in Example 1, and the viscosity of the epoxy resin composition obtained in Example 1 was compared. In the following composition, Epicoat 827 (manufactured by JER) means a bisphenol A type epoxy resin having an epoxy equivalent of 180 to 190 and a viscosity at 25 ° C. of 90 to 110 poise, and DICY is dicyandiamide (manufactured by DEGUSSA). And DCMU-99 means 3- (3,4-dichlorophenyl) -1,1-dimethylurea (Hodogaya Chemical Co.), ECN-1273 (Asahi Ciba Co.) has an epoxy equivalent of 210-240 g. / Eq cresol novolac type epoxy resin.

(Comparative Example 1)
Epicoat 827 100 parts by weight DICY 4.5 parts by weight

(Comparative Example 2)
Epicoat 827 100 parts by weight DICY 4.5 parts by weight DCMU-99 3 parts by weight

(Comparative Example 3)
Epicoat 827 40 parts by weight ECN-1273 60 parts by weight DICY 4.5 parts by weight DCMU-99 3 parts by weight

  The viscosity of the epoxy resin composition of Example 1 can be measured even under temperature conditions in the range of 25 to 70 ° C., and can be set to a desired viscosity by appropriately adjusting the temperature. Therefore, even when the filler is dispersed, it is possible to achieve uniform dispersion by adjusting the viscosity, and it is suggested that desired properties can be imparted to the prepreg and the formed body.

  On the other hand, even when the epoxy resin composition of Comparative Example 1 was reacted at 120 ° C. for 120 minutes, the reaction did not proceed, and an epoxy resin composition comparable to the examples could not be obtained. Incidentally, the reaction of the epoxy resin composition of Comparative Example 1 did not proceed even when the reaction time was 240 minutes, and as it was, it was poor in practicality as an epoxy resin composition. Further, the epoxy resin compositions of Comparative Examples 2 and 3 were not measurable because the viscosity was so high as to exceed the measurement limit of the viscosity measuring device. Therefore, the epoxy resin compositions of Comparative Examples 2 and 3 were expected to have difficulty in achieving the desired properties because the amount of filler used was limited or the dispersibility of the filler was reduced. . In any case, the epoxy resin compositions of Comparative Examples 1 to 3 could not adjust the viscosity under the above conditions.

[Test Example 2] Evaluation of tackiness of UD sheet Using the epoxy resin composition obtained in Example 1, a UD sheet (prepreg in which fibers were aligned in a single direction) was produced in the following manner. First, 4.5 parts by weight of dicyandiamide (DICY) as a second curing agent and 3 parts by weight of 3- (3,4-dichlorophenyl) -1,1-dimethylurea (DCMU-99) as a curing accelerator. Dissolved in a mixed solvent of methanol and acetone. This was added and mixed to the epoxy resin composition obtained in Example 1, and reacted at 130 ° C. for 60 minutes to obtain a desired resin composition for prepreg. The amount of the mixed solvent used is a minimum necessary amount for dissolving the second curing agent and the curing accelerator, and the viscosity of the resin composition for prepreg is within a range where the prepreg can be produced. The amount was within the range.

  Next, the prepreg was manufactured by the dipping method using the obtained resin composition for prepregs. That is, by impregnating the base material with the resin composition for prepreg at a line speed so that a desired amount of resin impregnates the base material, and then drying by heating, a semi-cured (B stage) UD sheet is obtained. Obtained. Carbon fiber (Torayca T-700S, manufactured by Toray Industries, Inc.) was used as the base material.

  As a control, a UD sheet was produced by the dipping method in the same manner as described above, using the epoxy resin compositions obtained in Comparative Examples 2 and 3. About the obtained UD sheet | seat, the surface of the UD sheet | seat was palpated and the tack property was evaluated on the following references | standards. The results are shown in Table 3.

×: When the UD sheet is touched, the impregnated resin adheres to the finger. ○: When the UD sheet is touched, the impregnated resin does not adhere to the finger.

[Test Example 3] Characteristic Evaluation of UD Plate Using the UD sheet obtained in Test Example 2, a completely cured (C stage) molded body was produced. That is, a plurality of UD sheets were overlapped and thermally cured for 180 minutes under the conditions of 130 ° C. and 0.3 MPa to obtain a UD plate on which the UD sheets were laminated. At this time, the fiber content (vol%) of the UD plate was set to 60 vol%. And using the obtained UD board, the following items were examined.

(1) Glass transition temperature Loss obtained by measuring loss tangent by dynamic viscoelasticity analysis (DMA) using a UD plate of length 8 mm x width 53 mm x thickness 1 mm or less as a sample at 10 ° C / min. The tangent peak value was defined as the glass transition temperature (Tg).

(2) Bending test The bending strength was measured based on "Bending test method of carbon fiber reinforced plastic" defined in JIS K7074. That is, a UD plate 15 mm long × 100 mm wide × 2 mm thick was used as a sample, and three-point bending was performed under the conditions of 5 mm / min and span 80 mm.

  The results are shown in Table 4. As shown in Test Example 2, the UD plate of Comparative Example 2 was inferior in tackiness of the prepreg, and could not be manufactured as a UD plate that could be compared with Example 1, so that measurement was impossible. did.

Claims (13)

An epoxy resin composition obtained by reacting an epoxy resin with a first curing agent for curing the epoxy resin,
The epoxy resin has an epoxy equivalent of 250 g / eq or less and a viscosity at 25 ° C. before curing of 300 poise or less,
The first curing agent is an aromatic amine;
Epoxy resin composition.   2. The epoxy according to claim 1, wherein the amount of the first curing agent is 1 to 10 parts by weight, based on the amount (100 parts by weight) of the epoxy resin for preparing the epoxy resin composition. Resin composition.   The epoxy resin composition according to claim 1 or 2, wherein the viscosity at 25 ° C is 1000 poise or more and the viscosity at 70 ° C is 200 poise or less.   The epoxy resin composition according to claim 1, wherein the aromatic amine has 2 to 7 amine functional groups.   The epoxy resin composition according to claim 4, wherein the amine functional group is a primary amine.   The epoxy resin composition according to any one of claims 1 to 5, wherein the aromatic amine is diaminodiphenylmethane and / or a derivative thereof.   The epoxy resin composition of any one of Claims 1-6 containing the 2nd hardening | curing agent which further hardens the epoxy resin in the said epoxy resin composition.   8. The epoxy according to claim 7, wherein the amount of the second curing agent is 3 to 50 parts by weight, based on the amount (100 parts by weight) of the epoxy resin for preparing the epoxy resin composition. Resin composition.   A prepreg formed by impregnating a base material with the epoxy resin composition according to claim 1.   A molded body obtained by heating and curing the prepreg according to claim 9. A method for producing an epoxy resin composition comprising a step of reacting an epoxy resin with a first curing agent,
The epoxy resin has an epoxy equivalent of 250 g / eq or less and a viscosity at 25 ° C. before curing of 300 poise or less,
The first curing agent is an aromatic amine;
A method for producing an epoxy resin composition.   The method for producing an epoxy resin composition according to claim 11, wherein the reaction between the epoxy resin and the first curing agent is performed at 100 to 140 ° C for 30 to 240 minutes.   Furthermore, the manufacturing method of the epoxy resin composition provided with the process of adding a 2nd hardening | curing agent to the said epoxy resin composition.