METHODS FOR PRODUCING CURABLE RESIN MIXTURE AND CURABLE RESIN COMPOSITION

Abstract

Provided are a curable resin mixture and a curable resin composition which contain a polyalkenylphenol resin and an aromatic polymaleimide compound having high crystallinity and a high melting point, and which exhibit excellent fluidity and reactivity. Also provided is a method for producing a curable resin mixture that contains: (A) a polyalkenylphenol resin which contains a polyalkenylphenol compound having at least 2 phenol skeletons in the molecule, a prescribed 2-alkenyl group being bonded to some or all of aromatic rings that form the phenol skeletons in the molecule; and (B) an aromatic polymaleimide compound. The method comprises: heating the aromatic polymaleimide compound (B) to the melting point or above and thereby melting the compound; and mixing the molten aromatic polymaleimide compound (B) and the polyalkenylphenol resin (A) within a temperature range at which the aromatic polymaleimide compound (B) does not recrystallize.

Claims

1. A method for producing a curable resin mixture containing a polyalkenylphenol resin (A) that comprises a polyalkenylphenol compound having at least two phenol skeletons in the molecule and a 2-alkenyl group represented by formula (1) bonded to all or a portion of the aromatic rings constituting the phenol skeletons in the molecule, and an aromatic polymaleimide compound (B), wherein the aromatic polymaleimide compound (B) is heated at or above its melting point to melt it, and the melted aromatic polymaleimide compound (B) and the polyalkenylphenol resin (A) are mixed in a temperature range in which the aromatic polymaleimide compound (B) does not recrystallize, ##STR00005## wherein in formula (1), R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 each independently represent a hydrogen atom, an alkyl group of 1 to 5 carbon atoms, a cycloalkyl group of 5 to 10 carbon atoms or an aryl group of 6 to 12 carbon atoms, and the * symbol in formula (1) represents a portion bonding with a carbon atom constituting part of an aromatic ring.

2. The method according to claim 1, further comprising mixing the melted aromatic polymaleimide compound (B) with the polyalkenylphenol resin (A) that is in a molten state.

3. The method according to claim 1, further comprising adding the polyalkenylphenol resin (A) in a molten state to the melted aromatic polymaleimide compound (B), and mixing them.

4. The method according to claim 1, wherein the polyalkenylphenol resin (A) comprises a polyalkenylphenol compound having structural units represented by formula (2)-1 and formula (2)-2, and when m is defined as the average number of structural units represented by formula (2)-1 per molecule and n is defined as the average number of structural units represented by formula (2)-2 per molecule, m is a real number of 1.1 to 35, m+n is a real number of 1.1 to 35, and n is a real number such that the value of the formula: m/(m+n) is 0.4 to 1, ##STR00006## wherein in formula (2)-1 and formula (2)-2, R.sup.6 each independently represents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or an alkoxy group of 1 to 5 carbon atoms, and R.sup.7 each independently represents a 2-alkenyl group represented by formula (1); R.sup.6 and R may be the same or different at each phenol skeletal unit; each Q independently represents an alkylene group represented by the formula —CR.sup.8R.sup.9—, a cycloalkylene group of 5 to 10 carbon atoms, a divalent organic group having an aromatic ring, a divalent organic group having an alicyclic fused ring, or a divalent organic group that is a combination of the foregoing; and R.sup.8 and R.sup.9 each independently represent a hydrogen atom, an alkyl group of 1 to 5 carbon atoms, an alkenyl group of 2 to 6 carbon atoms, a cycloalkyl group of 5 to 10 carbon atoms or an aryl group of 6 to 12 carbon atoms.

5. The method according to claim 1, wherein the number average molecular weight of the polyalkenylphenol resin (A) is 300 to 5000.

6. The method according to claim 1, wherein the aromatic polymaleimide compound (B) is a bismaleimide compound.

7. The method according to claim 1, comprising mixing 40 to 150 parts by mass of the polyalkenylphenol resin (A) with respect to 100 parts by mass of the aromatic polymaleimide compound (B).

8. The method according to claim 1, comprising mixing the melted aromatic polymaleimide compound (B) and the polyalkenylphenol resin (A) so that the number average molecular weight change X, represented by the formula: X=(Mn′/Mn)−1, where Mn is the number average molecular weight of the mixture obtained by mixing the polyalkenylphenol resin (A) and the aromatic polymaleimide compound (B) without heating, and Mn′ is the number average molecular weight of the curable resin mixture, is in the range of 0 to 2.0.

9. A curable resin mixture obtained by the method according to claim 1.

10. A method for producing a curable resin composition, comprising further mixing an additive (C) when the polyalkenylphenol resin (A) and the aromatic polymaleimide compound (B) are mixed in the method according to claim 1.

11. A method for producing a curable resin composition, comprising mixing an additive (C) with a curable resin mixture produced by the method according to claim 1.

12. The method according to claim 10, wherein the additive (C) comprises a filler.

13. The method according to claim 10, wherein the additive (C) comprises a curing accelerator.

14. A curable resin composition obtained by the method according to claim 10.

15. A cured product of the curable resin mixture according to claim 9.

16. The method according to claim 2, further comprising adding the polyalkenylphenol resin (A) in a molten state to the melted aromatic polymaleimide compound (B), and mixing them.

Description

EXAMPLES

[0055] The present invention will now be explained in greater detail using examples and comparative examples, with the understanding that the invention is not limited to the examples.

[0056] The starting materials in the examples and comparative examples were as follows.

Starting Materials

[0057] Polyalkenylphenol resin A: Resin obtained by allylating phenolic hydroxyl groups of phenol-novolak resin Shonol (registered trademark) BRG-558 (Showa Denko K.K.) at para positions (hydroxyl equivalents: 159, number average molecular weight: Mn 1600, weight average molecular weight: Mw 5400, melting point: 55° C.). The production method is described in Example 3 of Japanese Unexamined Patent Publication No. 2016-28129.

[0058] Polyalkenylphenol resin B: Resin obtained by allylating phenolic hydroxyl groups of phenol aralkyl resin HE-100C-12 (Air Water Inc.) at para positions (hydroxyl equivalents: 222, number average molecular weight: Mn 950, weight average molecular weight: Mw 1950, melting point: 20° C.). Refer to the Examples of Japanese Unexamined Patent Publication No. 2016-28129 for the production method.

[0059] Bismaleimide compound: BMI-4000 (bisphenol A-diphenyl ether bismaleimide, melting point: 165° C., Daiwakasei Industry Co., Ltd.) and BMI-1100H (4,4′-diphenylmethanebismaleimide, melting point: 160° C., Daiwakasei Industry Co., Ltd.).

[0060] Polymerization initiator: Percumyl D (NOF Corp.)

[0061] Silica filler: MSR2212 (spherical silica, mean particle size: 25.5 μm, Tatsumori, Ltd., treated with 0.5 mass % silane coupling agent KBM-403 (Shin-Etsu Chemical Co., Ltd.)).

[0062] The analysis methods and property evaluation methods used in the examples and comparative examples were as follows.

Analysis Methods

Molecular Weight

[0063] This was measured by GPC. The measuring conditions were as follows.

[0064] Apparatus: Shodex (registered trademark) GPC-101

[0065] Column: Shodex (registered trademark) KF-802, KF-803, KF-805

[0066] Mobile phase: tetrahydrofuran

[0067] Flow velocity: 1.0 mL/min

[0068] Detector: Shodex (registered trademark) RI (registered trademark)-71

[0069] Temperature: 40° C.

[0070] The number average molecular weight Mn and the weight average molecular weight Mw were calculated based on a calibration curve prepared using standard polystyrene, under the measuring conditions specified above.

Method of Calculating Number Average Molecular Weight Change X

[0071] The bismaleimide compounds and the polyalkenylphenol resins in the amounts specified in the Examples and Comparative Examples were weighed and dissolved in THF, and then the number average molecular weights (Mn) of the mixtures, and the number average molecular weights (Mn′) of the curable resin mixtures after mixing by the procedures described in the Examples and Comparative Examples, were each measured by GPC and the number average molecular weight change X was calculated using the formula: X=(Mn′/Mn)−1, as the increase ratio of Mn′ with respect to Mn. The number average molecular weight was determined by integrating the entire area including the peaks of the polyalkenylphenol resin and the aromatic polymaleimide compound.

Flexural Strength

[0072] Measurement was carried out using a TENSILON tester (model: MSAT0002RTF/RTG) by A&D Co., Ltd. The test strip shape was 750 mm length×10 mm width×3 mm thickness. A 3-point bending test was conducted 5 times at room temperature with a test speed of 2 mm/min, according to JIS K7171, and the average value was recorded as the flexural strength.

Glass Transition Temperature (Tg)

[0073] Measurement was carried out using a thermomechanical analyzer (TMA). A TMA/SS6100 thermomechanical analyzer by SII NanoTechnology Inc. was used for measurement of a 5 mm×5 mm×5 mm test strip under conditions with a temperature range of 30 to 300° C., a temperature-elevating rate of 5° C./min and a load of 20.0 mN, to determine the Tg.

Spiral Flow

[0074] The spiral flow was measured according to Japan Electrical Insulating and Advanced Performance Materials Industrial Association Standards EIMS T 901. By using a test die with an engraved spiral groove and a transfer molding machine (Matsuda Seisakusho, Co. Ltd.), and heating the top plate and die to 180° C. and molding at a pressure of 100 kg/cm.sup.2, the spiral flow value after a period of 3 minutes was measured.

(1) Production of Curable Resin Mixture

Example 1

[0075] BMI-4000 was added at 100 parts by mass into a reactor and heated and stirred at 170° C. When all of BMI-4000 had melted producing a transparent liquid, the temperature was lowered to 150° C. Polyalkenylphenol resin A that had been heated to 80° C. and melted was then added at 100 parts by mass to the reactor, and heated stirring was carried out at 150° C. for 10 minutes to mix the two resins. The curable resin mixture was then removed out. Since the number average molecular weight (Mn) before heating was 408 and the number average molecular weight (Mn′) after heating was 450, X was 0.1 (=450/408-1).

Example 2

[0076] BMI-4000 was added at 100 parts by mass to a twin roll that had been heated to 170° C. When all of BMI-4000 had melted producing a transparent liquid that had wrapped around the roll, the temperature was lowered to 150° C. Polyalkenylphenol resin A was then added at 100 parts by mass, and kneading was carried out at 150° C. for 10 minutes to mix the two resins. The curable resin mixture was then removed out.

Example 3

[0077] BMI-1100H was added at 100 parts by mass into a reactor and heated and stirred at 160° C. When all of BMI-1100H had melted producing a transparent liquid, the temperature was lowered to 150° C. Polyalkenylphenol resin A that had been heated to 80° C. and melted was then added at 100 parts by mass to the reactor, and heated stirring was carried out at 150° C. for 10 minutes to mix the two resins. The curable resin mixture was then removed out.

Example 4

[0078] BMI-4000 was added at 100 parts by mass into a reactor and heated and stirred at 170° C. When all of BMI-4000 had melted producing a transparent liquid, the temperature was lowered to 150° C. Polyalkenylphenol resin B that had been heated to 80° C. and melted was then added at 100 parts by mass to the reactor, and heated stirring was carried out at 150° C. for 10 minutes to mix the two resins. The curable resin mixture was then removed out.

Example 5

[0079] BMI-4000 was added at 100 parts by mass into a reactor and heated and stirred at 170° C. When all of BMI-4000 had melted producing a transparent liquid, the temperature was lowered to 150° C. Polyalkenylphenol resin A that had been heated to 80° C. and melted was then added at 200 parts by mass to the reactor, and heated stirring was carried out at 150° C. for 10 minutes to mix the two resins. The curable resin mixture was then removed out.

Comparative Example 1

[0080] Both 100 parts by mass of BMI-4000 and 100 parts by mass of polyalkenylphenol resin A were added into a reactor and heated and stirred at 180° C. After the two resins had each melted, heating and stirring was continued at 180° C. for 30 minutes. The curable resin mixture was then removed out.

Comparative Example 2

[0081] Both 100 parts by mass of BMI-4000 and 100 parts by mass of polyalkenylphenol resin A were added into a reactor and heated and stirred at 150° C. for 10 minutes. The curable resin mixture was then removed out.

Comparative Example 3

[0082] BMI-4000 was added at 100 parts by mass into a reactor and heated and stirred at 170° C. When all of BMI-4000 had melted producing a transparent liquid, the temperature was lowered to 100° C. A crystal-containing particulate substance precipitated in BMI-4000 during this time. Polyalkenylphenol resin A that had been heated to 80° C. and melted was then added at 100 parts by mass to the reactor, and heated stirring was carried out at 100° C. for 10 minutes to mix the two resins. The curable resin mixture was then removed out.

Comparative Example 4

[0083] A mill mixer (Model WB-1 by Osaka Chemical Co., Ltd.) was used for pulverizing, mixing and dispersing 100 parts by mass of BMI-4000 and 100 parts by mass of polyalkenylphenol resin A at 25° C. for 2 minutes, and then the curable resin mixture was removed out.

Comparative Example 5

[0084] Both 100 parts by mass of BMI-4000 and 100 parts by mass of polyalkenylphenol resin A were added into a reactor and heated and stirred at 170° C. for 15 minutes. Gelation proceeded in the reactor and the curable resin mixture could not be removed out.

(2) Evaluation of Curable Resin Compositions

[0085] The curable resin mixtures obtained by mixing as described above and the components listed in Table 1 were combined in the proportions listed in the table, and melt kneading was carried out (two rolls (8-inch roll diameter) by Toyo Seiki Co., Ltd., 110° C., 10 min). Each was then allowed to cool for 1 hour at room temperature (25° C.) for solidification, after which a mill mixer (model WB-1 by Osaka Chemical Co., Ltd., 25° C., 30 sec) was used for pulverizing to obtain the target powdered curable resin composition. The curable resin composition was used to fabricate a sample for the flexural strength test, using a transfer molding machine (Matsuda Seisakusho, Co. Ltd.) under conditions with a die temperature of 180° C., a molding pressure of I00 kgf/cm.sup.2 and a curing time of 180 seconds.

[0086] For measurement of the Shore D hardness, a transfer molding machine was used with a molding temperature of 180° C., and after a curing time of 2 minutes, the mold was opened and the Shore D hardness of the test strip was measured using a Shore D hardness meter.

[0087] The composition and preparation conditions for the curable resin mixture are shown in Table 2. The number average molecular weight change X of the curable resin mixture and the results of evaluating the properties of the curable resin composition are shown in Table 3.

TABLE-US-00001 TABLE 1 Component Content (pts by mass) Filler 80 Curable resin mixture 20 Polymerization initiator 0.13

TABLE-US-00002 TABLE 2 (A)/(B) State of component Component Component (pts by mass/ Mixing conditions (B) during addition Mixing (A) (B) pts by mass) (temperature/time) of component (A) method Example 1 Resin A BMI-4000 100/100 150° C./10 min Molten Stirring Example 2 Resin A BMI-4000 100/100 150° C./10 min Molten Twin roll Example 3 Resin A BMI-1100H 100/100 150° C./10 min Molten Stirring Example 4 Resin B BMI-4000 100/100 150° C./10 min Molten Stirring Example 5 Resin A BMI-4000 200/100 150° C./10 min Molten Stirring Comp. Resin A BMI-4000 100/100 180° C./30 min Non-molten Stirring Example 1 Comp. Resin A BMI-4000 100/100 150° C./10 min Non-molten Stirring Example 2 Comp. Resin A BMI-4000 100/100 100° C./10 min Crystalline Stirring Example 3 precipitated Comp. Resin A BMI-4000 100/100 25° C./2 min Powder Mill mixer Example 4 Comp. Resin A BMI-4000 100/100 170° C./15 min Non-molten Stirring Example 5

TABLE-US-00003 TABLE 3 Number average Spiral Flexural molecular weight Shore D flow strength Tg change X hardness (cm) (MPa) (° C.) Example 1 0.1 95 102 110 180 Example 2 0.0 90 98 100 170 Example 3 0.1 92 87 110 180 Example 4 0.2 85 128 104 160 Example 5 0.2 80 110 98 150 Comp. Example 1 2.1 85 30 90 143 Comp. Example 2 0.0 73 88 78 115 Comp. Example 3 0.1 70 100 80 120 Comp. Example 4 0.0 50 97 75 110

[0088] Table 3 shows that Examples 1 to 5 had reduced gelation during kneading, and the cured products also had satisfactory physical property values. On the other hand, in Comparative Examples 1 and 5 in which polyalkenylphenol resin (A) and aromatic polymaleimide compound (B) were mixed in a non-molten state and heated at above the melting point of (B), the molecular weight increased and the viscosity was higher. Moreover, in Comparative Examples 2 to 4 in which aromatic polymaleimide compound (B) was mixed in an incompletely molten state with polyalkenylphenol resin (A), the Shore hardness, flexural strength and Tg were all low, which suggests that the curing reaction efficiency was insufficient.

INDUSTRIAL APPLICABILITY

[0089] By using the method of the invention, it is possible to provide a curable resin composition with excellent workability, humidity resistance, heat resistance and mechanical strength, as well as electronic parts obtained by using the composition. Particularly, when used as a semiconductor sealing material in a power device, etc., the composition has excellent workability and fast-curing properties during molding, and after molding a cured product with high mechanical strength and high heat resistance may be obtained as a sealing material.