JP2012153768A - Method for manufacturing thermosetting resin molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a thermosetting resin molded product for controlling generation of bubbles capable of securing productivity.SOLUTION: The method for manufacturing a thermosetting resin molded product, which is cast molded a thermosetting resin composition containing a thermosetting resin and a curing agent, includes steps of: injecting the thermosetting resin composition into a mold and heating and holding the thermosetting resin composition in a first temperature region in which a vapor pressure of the curing agent is 0.05-0.5 mmHg; heating and holding the thermosetting resin composition in a second temperature region in which a vapor pressure of the curing agent is 1.0-3.0 mmHg by rising the temperature from the first temperature region; and heating and holding the thermosetting resin composition in the third temperature region in which a vapor pressure of the curing agent is equal to or more than 5.0 mmHg by rising the temperature from the second temperature region.

Description

  The present invention relates to a method for producing a thermosetting resin molded article in which a thermosetting resin composition containing a thermosetting resin and a volatile curing agent is cast and molded.

  Epoxy resin cured products are generally inexpensive, have excellent transparency, electrical insulation, chemical resistance, moisture resistance, adhesion, etc., and have a good balance between economy and performance. It is used in various fields such as adhesive materials and paint materials.

  Among these, epoxy resin cured products using acid anhydride curing agents are widely used for molding and the like because they are excellent in transparency and are difficult to be colored due to the high temperature during curing and the high temperature received from the environment after curing.

  For example, as an epoxy resin molded product using an acid anhydride curing agent, an optical semiconductor sealing material for protecting an optical semiconductor such as a light emitting element of a light emitting diode (LED) can be cited (see Patent Document 1). ).

  In Patent Document 1, when a quaternary ammonium salt is used as a curing accelerator in an epoxy resin composition using an acid anhydride curing agent, a cured product excellent in transparency having almost no discoloration at a curing temperature of 150 ° C. or lower is disclosed. It is described to give.

  In addition, by increasing the blending amount of the curing accelerator even in a low temperature range of 100 to 120 ° C., the mold can be released from the mold in a short time of about 30 to 60 minutes, and a cured product with no discoloration can be obtained. It is described that

Japanese Patent No. 2534642

  However, an epoxy resin molded product using an acid anhydride curing agent tends to generate bubbles when the size of the epoxy resin molded product is relatively large.

  That is, Patent Document 1 relates to sealing of an optical semiconductor such as an LED, and the epoxy resin molded product has a small size and a relatively simple shape. Specifically, an epoxy resin molded product having a small size as disclosed in Patent Document 1 has no problem even if it is molded at a curing temperature of 100 ° C. or higher. However, when the dimensions are increased as in the case of a housing equipment member or the like, generation of bubbles due to volatilization of the acid anhydride curing agent becomes a problem in the initial stage of curing. In addition to the volatilization of the acid anhydride curing agent due to heating, the curing reaction is an exothermic reaction, and a large amount of heat is generated during curing, so it is necessary to suppress volatilization due to the reaction heat of the resin.

  In particular, since many products such as housing equipment members are large in size and complicated in shape, once bubbles are generated, they are difficult to be removed, and the reaction heat of the curing reaction is easily generated, so that the problem of bubbles is likely to occur.

  Therefore, in order to suppress generation | occurrence | production of the bubble by volatilization of an acid anhydride hardening | curing agent, it is necessary to shape | mold on mild conditions as low as possible.

  However, in low temperature molding, it becomes difficult to obtain an epoxy resin molded product that can be removed from the mold and has high heat resistance, or it takes a very long time for molding. Therefore, productivity will fall.

  The present invention has been made in view of the circumstances as described above, and it is an object of the present invention to provide a method for producing a thermosetting resin molded product that can suppress the generation of bubbles and ensure productivity. .

  In order to solve the above problems, the method for producing a thermosetting resin molded article of the present invention casts and molds a thermosetting resin composition containing a thermosetting resin and a volatile curing agent. In the method for producing a thermosetting resin molded article, the thermosetting resin composition is injected into a mold, and the thermosetting resin is in a first temperature range in which the vapor pressure of the curing agent is 0.05 to 0.5 mmHg. The process of heating and holding the composition, and heating and holding the thermosetting resin composition in the second temperature range where the vapor pressure of the curing agent is 1.0 to 3.0 mmHg by raising the temperature from the first temperature range. And a step of heating and holding the thermosetting resin composition in a third temperature region in which the vapor pressure of the curing agent is 5.0 mmHg or higher by raising the temperature from the second temperature region. .

  In this method for producing a thermosetting resin molded product, the time for heating and holding in the first temperature range is 5.0 to 15 minutes, and the time for heating and holding in the second temperature range is 2.5 to 15 minutes. It is preferable.

  In this method for producing a thermosetting resin molded article, the curing agent is preferably an acid anhydride curing agent, and the thermosetting resin is preferably an epoxy resin.

  According to the method for producing a thermosetting resin molded article of the present invention, the generation of bubbles can be suppressed and the productivity can be ensured.

  The present invention is described in detail below.

  The method for producing a thermosetting resin molded product of the present invention generates bubbles when molding a thermosetting resin molded product, such as a housing equipment member, which is relatively large and often complicated in shape by casting. It has been completed in consideration of preventing the loss of productivity and reducing productivity. In order to realize this, it is characterized by performing two-stage low-temperature heating (first temperature region and second temperature region) in the initial stage of molding by casting.

  Specifically, heating is performed at a relatively low temperature until the reaction proceeds to a certain extent and three-dimensional crosslinking is formed, thereby suppressing the generation and remaining of bubbles. Then, after the reaction has progressed to some extent in the absence of bubbles, heating is performed at a high temperature in order to perform sufficient curing in a short time (third temperature region).

  Based on the above viewpoint, the manufacturing method of the thermosetting resin molded product of the present invention is finally subjected to the third temperature through two-stage low-temperature heating in the first temperature region and the second temperature region. It is characterized in that the molding is completed in the region.

  In the present invention, the vapor pressure of the curing agent can be measured as follows. Vapor pressure is the pressure of the vapor phase in equilibrium with the liquid phase at the temperature of the substance, and can be measured by a known vapor pressure measurement method such as a static method, a gas flow method, a boiling point method, or a method based on gas molecular motion. .

  The static method is a method in which the sample temperature is sampled from a sealed container, the sample temperature is kept constant, and the equilibrium vapor pressure at that temperature is directly measured using a pressure gauge.

  In the gas flow method, a carrier gas is made to contact a liquid sample at a constant temperature to saturate the vapor of the sample and measure the vapor density (evaporation volume / volume), assuming that the vapor follows the ideal gas law. This is a method for obtaining the vapor pressure.

The boiling point method is a method for obtaining a vapor pressure curve by measuring boiling points at various pressures.
These measuring methods can be used in combination. Further, when the vapor pressure is low beyond the measurement limit, the result of the measurable region can be graphed and an extrapolated value can be adopted. Furthermore, taking a measure such as applying the measurement result to the Clapeyron-Clauus equation to obtain an extrapolation value is effective for obtaining an accurate vapor pressure.

  Below, the manufacturing method of the thermosetting resin molded product of this invention is demonstrated concretely.

  The method for producing a thermosetting resin molded article of the present invention is to cast and mold a thermosetting resin composition containing a thermosetting resin and a volatile curing agent.

  As the thermosetting resin composition, a liquid thermosetting resin and a volatile curing agent which are cured by heating them can be suitably used. That is, it can be suitably used for those in which the curing agent volatilizes due to the heating temperature during molding and bubbles are easily generated.

  The “volatile” curing agent means that it is volatile at the heating temperature at the time of molding. In the present invention, it is solid at room temperature (25 ° C.) but becomes liquid at the heating temperature at the time of molding. It is also possible to use a curing agent that comes to have properties.

  Specific combinations of thermosetting resin / curing agent include, for example, epoxy resin / acid anhydride curing agent, epoxy resin / aliphatic amine curing agent, epoxy resin / aromatic amine curing agent, epoxy resin / alicyclic ring. Group amine curing agents and the like.

  Among these, the curing agent is preferably an acid anhydride curing agent, and the thermosetting resin is preferably an epoxy resin. When such a thermosetting resin composition is used, the three-stage heating in the first to third temperature regions described later is particularly effective for suppressing the generation of bubbles and ensuring the productivity.

  Although it does not specifically limit as an epoxy resin, For example, a liquid epoxy resin can be used at normal temperature (25 degreeC).

  Examples of the epoxy resin that is liquid at room temperature include bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, and alicyclic epoxy resins. These may be used alone or in combination of two or more.

  Further, an epoxy resin in which a normal epoxy resin such as a phenol novolac type epoxy resin, a triphenolmethane type epoxy resin, a high molecular weight bisphenol A type epoxy resin or the like is dissolved in the normal temperature liquid epoxy resin is used. You can also

  Among these, in consideration of combined use with an acid anhydride curing agent, physical properties of a thermosetting resin molded article, and the like, a bisphenol type epoxy resin that is liquid at room temperature is preferable. For example, a bisphenol type epoxy resin having an epoxy equivalent of 150 to 500 g / eq and a viscosity of 1000 to 50000 mPa · s (25 ° C.) can be used.

  As the acid anhydride curing agent, for example, an alicyclic acid anhydride, an aliphatic acid anhydride, or the like can be used.

  Examples of the alicyclic acid anhydride include methyltetrahydrophthalic anhydride such as tetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride, and methylhexahydroanhydride such as hexahydrophthalic anhydride and 4-methylhexahydrophthalic anhydride. Phthalic acid, methyl hymic anhydride and the like can be used. These may be used alone or in combination of two or more.

  As the aliphatic acid anhydride, for example, dodecenyl succinic anhydride, polyadipic acid anhydride, polyazeline acid anhydride and the like can be used. These may be used alone or in combination of two or more.

  Among these, alicyclic acid anhydrides are preferable in consideration of heat resistance and mechanical strength. As the alicyclic acid anhydride, for example, one having an acid anhydride equivalent of 150 to 400 g / eq can be used.

  The compounding amount of the acid anhydride curing agent is preferably such that the equivalent ratio of the anhydride group to the epoxy group (acid anhydride equivalent / epoxy group equivalent) is 0.5 to 1.5, more preferably. This is an amount that provides an equivalent ratio of 0.7 to 1.2. When the equivalent ratio is within such a range, insufficient curing can be suppressed and the heat resistance and strength of the thermosetting resin molded product can be increased.

  The thermosetting resin composition can contain a curing accelerator that promotes the reaction between the epoxy resin and the acid anhydride curing agent. Examples of the curing accelerator include 2-ethyl-4-methylimidazole, 2-heptadecylimidazole, 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 4-methyl. Imidazole, 4-ethylimidazole, 2-phenyl-4-hydroxymethylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxy Imidazoles such as methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, triethylamine, triethylenediamine, benzyldimethylamine, α-methylbenzyldimethylamine, triethanolamine, dimethylamino ester , Tertiary amines such as 2- (dimethylaminomethyl) phenol, tris (dimethylaminomethyl) phenol, 1,8-diazabicyclo [5.4.0] undecene-7, 1,5-diazabicyclo [4. 3.0] cycloamidines such as nonene-5,5,6-dibutylamino-1,8-diazabicyclo [5.4.0] undecene-7, quaternary ammonium salts such as tetrabutylammonium bromide, etc. be able to. These may be used alone or in combination of two or more.

  As for the compounding quantity of a hardening accelerator, 0.3-5.0 mass% is preferable with respect to the total amount of an epoxy resin and an acid anhydride hardening | curing agent. When the blending amount of the curing accelerator is within such a range, it is possible to suppress excessive progress of the curing reaction while promoting the curing reaction.

  The thermosetting resin composition may further contain other components within a range not impairing the effects of the present invention. As such other components, for example, inorganic fillers, colorants and the like can be used.

  The thermosetting resin composition can be prepared as follows. For example, a thermosetting resin, a curing agent, and other components as necessary are blended and mixed. The method of mixing is not particularly limited, but for example, a method of kneading by hand with a stirring bar, spatula, etc. in a suitable container, a method of kneading with a kneader such as a planetary mixer, a bead mill, or a three-roller, etc. Can be used.

  After mixing these, vacuum defoaming can be performed to prepare a thermosetting resin composition. These mixtures are stored in a state of two or more liquids in which a thermosetting resin and a curing agent are separated if necessary for suppressing a curing reaction during storage, and are mixed and used at the time of use.

  The thermosetting resin composition thus prepared preferably has a viscosity of 1000 to 100,000 mPa · s (25 ° C.), more preferably 1000 to 50000 mPa · s (25 ° C.). If it is in such a viscosity range, workability | operativity etc. in cast molding can be made favorable.

  The thermosetting resin composition can be molded using a casting mold. For example, a cavity is formed between the upper mold and the lower mold of the mold, and the thermosetting resin composition is injected into the cavity with an injection nozzle or the like. And the thermosetting resin composition in a cavity is heated with the heating apparatus provided in the metal mold | die, after shaping | molding, it can shape | mold by taking out and taking out a molded article.

  The method for producing a thermosetting resin molded article of the present invention is suitable for applications in which bubbles are easily generated and productivity is required, and the dimensions are relatively large and the shape is complicated.

  Specifically, it is suitable for a relatively large thermosetting resin molded product having a single casting amount of several hundred grams to several tens of kilograms, for example, suitable for a housing equipment member.

  Examples of housing equipment include kitchen counters, kitchen sinks, wash counters, wash bowls, wash cabinets, bathtubs, bathtub lids, bathtub pans, bathroom floors, bathroom walls, bathroom ceilings, bathroom counters, toilet bowls, hand-washing bowls, etc. be able to.

  In the method for producing a thermosetting resin molded article of the present invention, the thermosetting resin composition as described above is injected into a mold, and the vapor pressure of the curing agent is 0.05 to 0.5 mmHg, preferably 0. The thermosetting resin composition is heated and held in a first temperature range of 1 to 0.3 mmHg. Generation | occurrence | production of a bubble can be suppressed by heating and holding a thermosetting resin composition in such a 1st temperature range.

  That is, by holding the thermosetting resin composition in this first temperature range, rapid increase in the vapor pressure of the curing agent due to rapid temperature rise and generation of bubbles due to reaction heat are suppressed. And generation | occurrence | production of a bubble is also suppressed by advancing the three-dimensional bridge | crosslinking of a thermosetting resin composition to some extent.

  If the thermosetting resin composition is directly heated to a temperature equal to or higher than the second temperature range described later without holding the thermosetting resin composition in the first temperature range, bubbles are likely to be generated due to rapid temperature rise or the like. Become.

  Further, even if molding is attempted while being heated and held in the first temperature range, curing does not proceed sufficiently and a thermosetting resin molded product cannot be obtained, or the glass transition temperature becomes very low. End up.

  When an acid anhydride curing agent, particularly an alicyclic acid anhydride such as tetrahydrophthalic anhydride is used as the curing agent, the first temperature range is, for example, about 50 to 70 ° C.

  The time for heating and holding in the first temperature region is preferably 5.0 to 15 minutes, and more preferably 5.0 to 10 minutes. By setting the time for heating and holding in the first temperature range to be within such a range, generation of bubbles can be suppressed and productivity can be ensured.

  When heating and holding in the first temperature range, two or more stages of heating temperature are set within the range of the first temperature range, and the heating is held within the above time range as a whole. May be.

  Next, in the method for producing a thermosetting resin molded product of the present invention, the temperature is raised from the first temperature range and the curing temperature is set to a second temperature range where the vapor pressure of the curing agent is 1.0 to 3.0 mmHg. The heat-resistant resin composition is heated and held. Generation | occurrence | production of a bubble can be suppressed by heating and holding a thermosetting resin composition in such a 2nd temperature range.

  That is, by keeping the thermosetting resin composition heated in this second temperature range, the vapor pressure of the curing agent is rapidly increased due to a rapid temperature rise from the first temperature range to the third temperature range described later. Suppresses the generation of bubbles due to rising and reaction heat. And by carrying out heat holding, the three-dimensional bridge | crosslinking of a thermosetting resin composition is advanced further, and generation | occurrence | production of the bubble by the temperature rising to the 3rd temperature range mentioned later is suppressed.

  When the thermosetting resin composition is directly heated from the first temperature region to a temperature equal to or higher than the third temperature region described later without holding the thermosetting resin composition in the second temperature region, bubbles are generated due to rapid temperature increase. To do.

  Further, even if the molding is attempted without increasing the temperature while being heated and held in the second temperature range, the curing does not proceed sufficiently and a thermosetting resin molded product cannot be obtained, or the glass transition temperature is low. It will be very low. For example, in a thermosetting resin composition using a bisphenol A type epoxy resin as a thermosetting resin and an alicyclic acid anhydride such as tetrahydrophthalic anhydride as a curing agent, the thermosetting resin having a glass transition temperature of 100 ° C. or higher. It is often difficult to obtain a resin molded product.

  When an acid anhydride curing agent, particularly an alicyclic acid anhydride such as tetrahydrophthalic anhydride, is used as the curing agent, the second temperature range is, for example, about 85 to 90 ° C.

  The time for heating and holding in the second temperature region is preferably 2.5 to 15 minutes, and more preferably 3.0 to 8.0 minutes. By setting the time for heating and holding in the second temperature range to be within such a range, the generation of bubbles can be suppressed and the productivity can be secured.

  When heating and holding in the second temperature range, two or more heating temperatures are set within the range of the second temperature range, and the heating and holding is performed within the above time range as a whole. May be.

  Next, in the method for producing a thermosetting resin molded article of the present invention, the third temperature at which the vapor pressure of the curing agent is increased to 5.0 mmHg or more, preferably 8.0 mmHg or more by raising the temperature from the second temperature range. The thermosetting resin composition is heated and held in the region. By heating and holding the thermosetting resin composition in such a third temperature range, the thermosetting resin composition can be sufficiently cured in a short time.

  That is, since the three-dimensional crosslinking has progressed to a considerable extent in a state where no bubbles are generated by passing the step of heating and holding the thermosetting resin composition in the first and second temperature regions, the second temperature Even if the temperature is increased from the region to the third temperature region, it is possible to suppress an increase in the vapor pressure of the curing agent and generation of bubbles due to reaction heat.

  When the thermosetting resin composition is heated and held in this third temperature region and cured, the curing proceeds sufficiently and a thermosetting resin molded article having a sufficiently high glass transition temperature can be obtained. For example, in a thermosetting resin composition using a bisphenol A type epoxy resin as a thermosetting resin and an alicyclic acid anhydride such as tetrahydrophthalic anhydride as a curing agent, the glass transition temperature is 100 ° C. or higher, preferably 110 A thermosetting resin molded article having a temperature of 0 ° C. or higher can be obtained.

  When an acid anhydride curing agent, particularly an alicyclic acid anhydride such as tetrahydrophthalic anhydride, is used as the curing agent, the third temperature range is, for example, 100 ° C. or higher, preferably about 110 to 125 ° C. .

  The time for heating and holding in the third temperature range is preferably 20 to 100 minutes, more preferably 30 to 60 minutes. By setting the time for heating and holding in the third temperature range to be within such a range, curing can be advanced to such an extent that a sufficiently high glass transition temperature is obtained, and productivity can be secured.

  In addition, when heating and holding in the third temperature range, two or more heating temperatures are set within the range of the third temperature range, and the heating is held within the time range as described above as a whole. It may be.

  In the method for producing a thermosetting resin molded article of the present invention, the entire curing time by multi-stage heating from the first temperature region to the third temperature region is preferably 45 to 120 minutes, more preferably 45 to 90 minutes. preferable. Productivity can be secured by setting the entire curing time within such a range.

  It should be noted that curing and molding are performed by multi-step heating from the first temperature range to the third temperature range in the mold cavity, and after demolding, the mold is further heated and held at a predetermined temperature for post-curing. You may make it perform.

  According to the method for producing a thermosetting resin molded article of the present invention, it is possible to obtain a thermosetting resin molded article having no bubbles and good appearance and having heat resistance.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

  As the epoxy resin, a liquid bisphenol A type epoxy resin (“EPICLON (registered trademark) 840S” manufactured by DIC Corporation, epoxy equivalent of 180 to 190 g / eq, viscosity of 9000 to 11000 mPa (25 ° C.)) was used.

  Tetrahydrophthalic anhydride (“EPICLON (registered trademark) B-570H” manufactured by DIC Corporation, acid anhydride equivalent 166 g / eq, viscosity 40 mPa · s (25 ° C.)) was used as the acid anhydride curing agent.

  As a curing accelerator, 2-ethyl-4-methylimidazole (“Cureazole (registered trademark) 2E4MZ” manufactured by Shikoku Kasei Kogyo Co., Ltd.) was used.

  An epoxy resin composition was prepared by blending 100 parts by mass of an epoxy resin, 100 parts by mass of an acid anhydride curing agent, and 2 parts by mass of a curing accelerator, and mixing them, followed by vacuum degassing.

  As a casting mold, a mold having a cavity constituted by an upper mold and a lower mold in which an elliptical sink miniature having a size of 30 cm × 20 cm × depth 15 cm is formed was used. The epoxy resin composition was cast into this mold and molded by heating under the conditions shown in Tables 2 and 3.

以上のようにして成形したエポキシ樹脂成形品について次の評価を行った。 Note that the vapor pressure of the acid anhydride curing agent was measured by a static method. Table 1 shows the vapor pressure of 25 ° C to 120 ° C.

The following evaluation was performed about the epoxy resin molded product shape | molded as mentioned above.

[Evaluation of bubbles]
The epoxy resin molded product was visually checked for the presence of bubbles and evaluated according to the following criteria.
◯: No bubbles were observed in the molded product, or only a few were observed.
(Triangle | delta): The bubble which can be visually observed in the molded article was seen a little.
X: Many air bubbles which can be observed visually in a molded article were seen.

[Glass-transition temperature]
In order to evaluate the curing level of the epoxy resin molded product, the glass transition temperature was measured by differential scanning calorimetry using a differential scanning calorimeter (“EXSTAR DSC6000” manufactured by SII NanoTechnology Co., Ltd.).

The evaluation results are shown in Tables 2 and 3.

  From Table 3, as shown in Comparative Examples 1 and 2, if the heating at the first stage is 90 ° C. or higher (hardening agent vapor pressure of 0.5 mmHg or higher), bubbles are generated in the epoxy resin molded product.

  Therefore, in order to avoid the generation of bubbles, as shown in Comparative Example 3, when heating at the first stage is set to 70 ° C. (hardening agent vapor pressure of 0.5 mmHg or less) and the temperature is set to 70 ° C. without increasing the temperature, Although generation | occurrence | production is avoided, since reaction advances moderately, hardening of an epoxy resin composition became inadequate and the glass transition point was not able to be measured.

  Therefore, in order to sufficiently cure while avoiding the generation of bubbles, as shown in Comparative Example 4, the first stage heating is 70 ° C./20 minutes (hardening agent vapor pressure 0.5 mmHg or less), the second stage heating. Is 120 ° C./26 minutes (curing agent vapor pressure 13 mmHg), bubbles are generated in the epoxy resin molded product. This is presumably because the temperature was raised to 120 ° C. in the second stage even though the reaction progressed slightly in the first stage and almost no three-dimensional crosslinking was formed.

  Therefore, in order to ensure sufficient hardening while avoiding the generation of bubbles, as shown in Comparative Example 5, the first stage heating is 70 ° C./20 minutes (hardening agent vapor pressure 0.5 mmHg or less), the second stage. When heating at 85 ° C./26 minutes (curing agent vapor pressure 1.5 mmHg), although the generation of bubbles was avoided, the glass transition point was as low as 75 ° C., and the required curing level was not satisfied within a predetermined time. It was. As shown in Comparative Example 6, the first stage heating was 70 ° C./20 minutes (curing agent vapor pressure 0.5 mmHg), and the second stage heating was 90 ° C./26 minutes (hardening agent vapor pressure 2.5 mmHg). Was the same.

  On the premise of the above points, three or more stages of heating were attempted in order to sufficiently cure while avoiding the generation of bubbles. From Table 2, as shown in Example 1, heating at the first stage is 70 ° C./7 minutes (hardening agent vapor pressure 0.5 mmHg or less), heating at the second stage is 90 ° C./3.5 minutes (curing) By setting the agent vapor pressure to 2.5 mmHg), a three-dimensional cross-linking is formed to some extent while the reaction is proceeding gradually, and further, the third stage heating is 110 ° C./3.5 minutes, and the fourth stage heating is 120 degrees. By setting the temperature to 32 ° C./32 minutes (curing agent vapor pressure 13 mmHg), the epoxy resin could be sufficiently cured.

  As shown in Example 2, the heating was performed at a temperature lower than that of Example 1, but the heating time at 90 ° C. was set longer than that of Example 1, thereby omitting the heating at 110 ° C. to 120 ° C. In the same manner as in Example 1, a sufficiently cured epoxy resin molded product without bubbles was obtained.

  As shown in Example 3, while the initial heating is the same as in Example 1, even if the maximum heating temperature is 110 ° C. and the molding conditions are simplified, there is no air bubble as in Example 1, and the epoxy is sufficiently cured. A resin molded product could be obtained.

  As shown in Example 4, even if the second stage heating from Example 3 was changed to 85 ° C. (curing agent vapor pressure 1.5 mmHg), the generation of bubbles was suppressed.

  As shown in Example 5, even when the maximum heating temperature was changed to 100 ° C. from Example 3, a cured epoxy resin molded product was obtained although a decrease in the glass transition temperature was observed, and the generation of bubbles was also suppressed. It was done.

  In the evaluation of bubbles in Tables 2 and 3, no or almost no bubbles were generated in Examples 1 to 5, and all were evaluated as ◯. In Comparative Examples 1, 2, and 4, many bubbles were generated. All were evaluated as x, and there was no result corresponding to the above Δ.

  From the above, the step of heating and holding the thermosetting resin composition in the first temperature region where the vapor pressure of the curing agent is 0.05 to 0.5 mmHg, and the temperature of the curing agent by raising the temperature from the first temperature region A step of heating and holding the thermosetting resin composition in a second temperature range where the vapor pressure is 1.0 to 3.0 mmHg, and a temperature rise from the second temperature range to set the vapor pressure of the curing agent to 5.0 mmHg By including the step of heating and holding the thermosetting resin composition in the third temperature region as described above, it was possible to suppress the generation of bubbles and ensure productivity.

Claims (3)

  In a method for producing a thermosetting resin molded article, in which a thermosetting resin composition containing a thermosetting resin and a volatile curing agent is cast and molded, the thermosetting resin composition is injected into a mold. And heating and holding the thermosetting resin composition in a first temperature range where the vapor pressure of the curing agent is 0.05 to 0.5 mmHg, and raising the temperature from the first temperature range to A step of heating and holding the thermosetting resin composition in a second temperature region where the vapor pressure of the curing agent is 1.0 to 3.0 mmHg; and a temperature rise from the second temperature region to And a step of heating and holding the thermosetting resin composition in a third temperature range where the vapor pressure is 5.0 mmHg or more.   The time for heating and holding in the first temperature region is 5.0 to 15 minutes, and the time for heating and holding in the second temperature region is 2.5 to 15 minutes. Manufacturing method of thermosetting resin molded product.   The method for producing a thermosetting resin molded article according to claim 1, wherein the curing agent is an acid anhydride curing agent, and the thermosetting resin is an epoxy resin.