JP2015117285A - Mixture containing polyphenylene ether - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mixture which provides a cured material having a low dielectric constant and dielectric tangent inherent to PPE, provides a cured material having excellent heat resistance and adhesiveness, can be coated at ordinary temperature, has excellent dispersion stability of PPE and a curable resin composition containing PPE, and can, when producing a prepreg, form uniform layers of PPE and a curable resin composition containing PPE.SOLUTION: Provided is a mixture containing polyphenylene ether and a solvent, where (1) the polyphenylene ether has a number average molecular weight of 5000 to 40000, and (2) the solvent is a mixture of a compound (A) which includes at least one compound selected from compounds whose amount held by the polyphenylene ether is 1500 mass% or more, and a compound (B) which includes at least one compound selected from compounds whose amount held by the polyphenylene ether is 300 mass% or more and less than 1500 mass%, and which contain a cyclic structure in the molecule.

Description

  The present invention is formed using a mixed solution containing polyphenylene ether (hereinafter also referred to as PPE) suitable as an electronic substrate material, a resin varnish containing the mixed solution, and a base material, and the prepreg. The present invention relates to a laminated board for electric and electronic parts and a printed wiring board.

  In recent years, due to remarkable progress in information network technology and expansion of services utilizing information networks, electronic devices are required to have a large amount of information and a high processing speed. In order to transmit a large amount of digital signal at high speed, it is effective to shorten the wavelength of the signal, and the frequency of the signal is increasing. However, since an electric signal in a high frequency region is easily attenuated by a wiring circuit, a printed wiring board having good transmission characteristics is required.

  PPE has a low dielectric constant and dielectric loss tangent, and is excellent in high-frequency characteristics, that is, dielectric characteristics. Therefore, PPE is suitable as a material for printed wiring boards of electronic devices using a high frequency band.

  On the other hand, since PPE lacks solubility in organic solvents, when producing prepregs necessary for printed wiring board production, varnish is produced by dissolving in a halogen-based solvent such as chloroform, or at 50 ° C. or higher. It was necessary to produce a varnish by dissolving it in a heated aromatic organic solvent such as toluene or xylene.

  Further, when the prepreg is produced with such a varnish, there is a problem that the PPE easily holds the solvent, and as the resin layer becomes thick, the resin layer is easily cracked due to drying.

  In order to solve this problem, Patent Document 1 uses a low-molecular-weight PPE, so that it has excellent solubility in an aromatic organic solvent at room temperature, and the fluidity of the molten resin is good, allowing multilayering. PPE resin compositions are described. Patent Document 2 reports a technique for converting a terminal hydroxyl group of a low molecular weight PPE into a reactive functional group to improve solubility in a solvent and improve heat resistance.

  In Patent Documents 3 and 4, a toluene resin liquid containing a crosslinkable resin such as PPE and a styrene butadiene copolymer and a resin composition containing a crosslinking aid such as triacyl isocyanurate is once heated to 35 ° C. and then cooled. In addition, there is described a method of preparing an opaque dispersion in which particles of a resin composition containing PPE, a crosslinkable resin, and a crosslinking aid are dispersed.

  Further, Patent Document 5 describes a method of dispersing PPE resin powder having an average particle diameter of 10 to 50 μm in a solvent such as methyl ethyl ketone, and Patent Document 6 describes a method of dispersing PPE particles of 106 μm or less in an aqueous system. ing.

JP 2002-265777 A Special table 2009-509912 JP 7-292126 A JP-A-9-290481 JP 2008-50526 A JP 2003-34731 A

  However, the method of increasing the solubility in a solvent using the low molecular weight PPE described in Patent Document 1 has a problem that the heat resistance of the resulting laminate is reduced, and the number of terminal hydroxyl groups of the PPE increases. Since this causes a problem that the ratio and the dielectric loss tangent are increased, it is not sufficient for use in a printed wiring board.

  In addition, the method of increasing the solubility in a solvent using the low molecular weight / reactive functionalized PPE described in Patent Document 2 improves the problem of heat resistance reduction due to the low molecular weight, but seals the terminal hydroxyl group. It has a problem that is presumed to be caused by this. That is, such PPE does not have sufficient adhesion to a substrate such as glass cloth or copper foil, and has low peel strength between layers in the case of a laminated plate or peel strength between the PPE and copper foil. Alternatively, there is a problem that water absorption resistance and solder heat resistance are not sufficient.

  In the methods described in Patent Documents 3 and 4, the dispersion of particles of a resin composition containing PPE, a crosslinkable resin, and a crosslinking aid has a very high viscosity. Is not sufficient in that it is difficult to obtain and inferior in impregnation into the substrate. Actually, when the method disclosed in Example 1 and Example 2 of Patent Document 3 is traced faithfully, the dispersion becomes grease-like and cannot be used for coating or it can be barely applied. However, the impregnation into the base material was poor, and only an inferior adhesive property between the base material and the resin composition was obtained. As described above, when the temperature is lowered under conditions of high concentration and high viscosity in which PPE, processable resin, and crosslinkable resin are mixed, crystallization of PPE does not grow, and it is very small but swells by incorporating the solvent inside. It is considered that a large number of crystals were generated and these crystal particles were aggregated to form a grease.

  The method described in Patent Document 5 is sufficient in that polyphenylene ether is dispersed in a poor solvent, so that the dispersion stability of the dispersion is insufficient and PPE is liable to settle and lacks uniform coating properties and continuous coating properties. There wasn't. In addition, when impregnating a substrate such as glass cloth, there is a problem that only the PPE is deposited on the impregnation roll or the like because the moving speed of the dispersion solvent and the PPE to the substrate is greatly different.

The method described in Patent Document 6 is stably dispersed in an aqueous solvent using a surfactant. However, since the PPE particles are as large as 106 μm or less, the method is described in Patent Document 6, for example. When TAIC is used as a curable monomer and a curable resin composition, PPE and TAIC cannot be completely dissolved in the process of normal heating and pressure molding conditions, and the resulting substrate lacks uniformity. It had disadvantages inferior to solder heat resistance and drill workability.
As described above, it gives a cured product having a low dielectric constant and dielectric loss tangent inherent to PPE, gives a cured product having excellent heat resistance and adhesiveness, and is excellent in dispersion stability of a resin composition containing PPE and PPE. However, no technique has been found regarding a mixed solution that can obtain a prepreg in which a PPE or a resin composition forms a uniform layer by coating at room temperature, and a mixed solution having the above-mentioned characteristics is strongly desired. It was.

  Under the circumstances described above, the problem to be solved by the present invention is to provide a cured product having a low dielectric constant and dielectric loss tangent inherent in PPE, and to have excellent heat resistance and adhesiveness (for example, delamination between layers in a multilayer board). A cured product having a strength or a peel strength between a cured product of the curable resin composition and a metal foil such as a copper foil) and can be applied at room temperature, and the dispersion stability of the curable resin composition containing PPE or PPE It is providing the liquid mixture which is excellent in property and can form the layer of the curable resin composition containing PPE and PPE uniform at the time of prepreg manufacture. The subject of the present invention further includes, in a specific embodiment, a curable resin composition containing PPE or PPE and a crosslinkable curable resin, a mixed solution containing a solvent, the curable resin composition and a substrate. It is providing the printed wiring board containing the prepreg for printed wiring boards, the hardened | cured material of this curable resin composition, and a base material.

  As a result of intensive investigations and repeated experiments to solve the above-mentioned problems, the present inventors, as described later, PPE having a specific molecular weight, a compound (A) having a specific solvent retention amount of PPE, and PPE A solvent containing PPE and a solvent, more specifically, a curable composition containing PPE, by using a solvent which is a mixture with the compound (B) having a specific solvent retention amount and having a ring structure in the molecule. It has been found that since the fluidity and dispersion stability of the mixed solution containing the resin composition are enhanced, the varnish containing the mixed solution can be applied at room temperature. Furthermore, the present inventors use a combination of the compound (A) and the compound (B) selected from two compound groups having different solvent retention amounts, so that a curable resin containing PPE in the prepreg obtained. It has been found that it becomes easier to form a uniform layer of the composition. Furthermore, the present inventors have found that the adhesiveness between the cured product of the curable resin composition containing PPE and the substrate produced from the prepreg by, for example, heat and pressure molding is good. Based on this finding, the inventors have completed the present invention.

  That is, the present invention is as follows.

[1] A liquid mixture containing polyphenylene ether and a solvent,
(1) The number average molecular weight of the polyphenylene ether is 5000 to 40000,
(2) The solvent is
A compound (A) that is one or more selected from compounds having a solvent retention of 1500% by mass or more of the polyphenylene ether;
The liquid mixture which is a mixture with the compound (B) which is 1 type or more selected from the compound whose solvent holding | maintenance amount of the said polyphenylene ether is 300 mass% or more and less than 1500 mass%, and has a ring structure in a molecule | numerator.
[2] The mixed liquid according to [1], wherein the ratio of the compound (A) to the entire solvent is 10% by mass or more and 90% by mass or less.
[3] The mixed solution according to [1] or [2], wherein the compound (B) has a boiling point higher than that of the compound (A).
[4] The mixed liquid according to [3], wherein the boiling point of the compound (B) is 18 ° C. or more higher than the boiling point of the compound (A).
[5] The mixed solution according to any one of [1] to [4], wherein the ring structure of the compound (B) is a 4-membered ring to an 8-membered ring.
[6] The mixed solution according to any one of [1] to [5], wherein the compound (B) is a ketone compound or an alkene compound.
[7] The mixed liquid according to any one of [1] to [6], further including a crosslinkable curable resin and an initiator.
[8] The mixed liquid according to [7] above, wherein the crosslinkable curable resin is a monomer having two or more vinyl groups in the molecule.
[9] The mixed liquid according to [8], wherein the crosslinkable curable resin is triallyl isocyanurate (TAIC).
[10] A resin varnish containing the mixed liquid according to any one of [1] to [9].
[11] A prepreg obtained by applying a resin varnish containing the mixed solution according to any one of [1] to [9] to a base material, and then removing the solvent from the base material.
[12] A printed wiring board produced using the prepreg according to [11] as a constituent component.

  According to the present invention, a cured product having a low dielectric constant and dielectric loss tangent inherent to PPE is provided, and excellent heat resistance and adhesiveness (for example, peel strength between layers in a multilayer board, or cured product of a curable resin composition) Can be applied at room temperature, has excellent dispersion stability of curable resin compositions containing PPE and PPE, and is uniform during prepreg manufacturing. The liquid mixture which can form the layer of the curable resin composition containing this can be obtained. Furthermore, according to the specific aspect of this invention, the printed wiring board prepreg containing the curable resin composition and a base material, and the printed wiring board containing the hardened | cured material and base material of this curable resin composition are obtained. be able to.

  Hereinafter, although the embodiment of the present invention is described in detail, it is not intended that the present invention be limited to these embodiments.

<Mixed liquid>
One embodiment of the present invention is a mixed solution containing PPE and a solvent. Typically, the liquid mixture includes PPE, a cross-linkable curable resin, and a solvent. Typically, at least a portion of the PPE is dispersed in the mixture in the form of particles.

｛式中、Ｒ１、Ｒ２、Ｒ３及びＲ４は、各々独立して、水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアルコキシ基、置換基を有してもよいアリール基、置換基を有してもよいアミノ基、ニトロ基又はカルボキシル基を表す。｝で表される繰返し構造単位を含む。 The PPE contained in the mixed liquid of this embodiment is preferably the following general formula (1):

{Wherein R1, R2, R3 and R4 each independently have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent. An aryl group that may be substituted, an amino group that may have a substituent, a nitro group, or a carboxyl group. } Is included.

  Specific examples of PPE include poly (2,6-dimethyl-1,4-phenylene ether), poly (2-methyl-6-ethyl-1,4-phenylene ether), and poly (2-methyl-6). -Phenyl-1,4-phenylene ether), poly (2,6-dichloro-1,4-phenylene ether) and the like, and 2,6-dimethylphenol and other phenols (for example, 2,3,6-phenylene ether) And a polyphenylene ether copolymer obtained by coupling 2,6-dimethylphenol and biphenols or bisphenols, and the like. . A preferable example from the viewpoint of dielectric constant and dielectric loss tangent is poly (2,6-dimethyl-1,4-phenylene ether).

  In the present disclosure, polyphenylene ether, that is, PPE means a polymer composed of a substituted or unsubstituted phenylene ether unit structure, but includes other copolymerization components as long as the effects of the present invention are not impaired. But you can.

  The number average molecular weight of PPE contained in the mixed solution is 5,000 or more and 40,000 or less. A preferable range of the number average molecular weight of PPE is 8,500 or more and 30,000 or less, and a more preferable range is 9,000 or more and 25,000 or less.

  If the number average molecular weight of PPE is 5,000 or more, the water absorption resistance, solder heat resistance, and adhesiveness of a cured product, for example, desired for printed wiring boards (for example, peel strength between layers in multilayer boards, or curing) The peel strength between the cured product of the conductive resin composition and the copper foil, etc.) is good. Moreover, if the number average molecular weight of PPE is 40,000 or less, the melt viscosity of the curable resin composition at the time of molding is small, and good moldability is obtained.

  Here, the number average molecular weight of PPE is a value determined by the following measurement. The solvent is dried and removed from the mixed solution containing PPE and the solvent at a temperature not higher than the boiling point of the solvent (the boiling point in this case refers to the boiling point of the compound having the highest boiling point among the contained compounds). A product having a solvent content of 1% by mass or less is obtained. Next, 20 g of a mixed solvent of toluene and methanol having a mass ratio of 95: 5 at 23 ° C. ± 3 ° C. is added to 1.5 g of this product. Allow 1 hour to elapse while shaking vigorously every 5 minutes in a constant temperature room at 23 ° C. ± 2 ° C. Next, it is allowed to stand for 24 hours in the same constant temperature room. Next, the supernatant liquid is removed, 5 g of a mixed solvent of toluene and methanol having a mass ratio of 95: 5 is added, and the mixture is shaken vigorously, and then allowed to stand in the same thermostatic chamber for 24 hours. Next, the supernatant is removed, and 5 g of a mixed solvent of toluene and methanol with a mass ratio of 95: 5 is added. Next, after substantially all of the solvent is removed by drying, the dried product is developed in chloroform, and insolubles are removed by filtration to obtain an extract (hereinafter, this extract is referred to as “extract (A)”. .)

  Gel permeation using the extract (A) as a measurement sample, Shodex LF-804 × 2 (manufactured by Showa Denko KK) as a column, chloroform at 50 ° C. as an eluent, and RI (refractometer) as a detector Chromatography (GPC) measurement is performed, and the value measured in terms of standard polystyrene is defined as the number average molecular weight of PPE from the relational expression between the molecular weight of the standard polystyrene sample measured under the same conditions and the elution time.

  Further, when at least a part of PPE is dissolved in a solvent due to the molecular weight distribution of the PPE used, the number average molecular weight of the dissolved PPE is a value determined by the following measurement. According to the above-mentioned procedure, all the supernatant liquid obtained in the process of obtaining the extract (A) is recovered. From this supernatant, soluble components are separated by silica gel column chromatography to obtain a PPE separation liquid. Next, the molecular weight of PPE contained in the PPE separation liquid is determined by GPC measurement and standard polystyrene conversion by the same method as the measurement of the number average molecular weight of PPE related to the extract (A). The obtained value is defined as the number average molecular weight of PPE dissolved in the solvent.

  Regarding the adhesiveness between the base material and the cured product of the curable resin composition described later, when producing a cured product composite from a prepreg, the normal PPE is usually PPE under the normal heat-pressure molding conditions of the prepreg. The melting rate is slower than other thermosetting resin components. Therefore, the presence of PPE causes the thermosetting resin component other than PPE to first melt and cover the surface of the base material, and then PPE melts with a delay, and the thermosetting resin component other than PPE and PPE Since it hardens | cures in the state mutually compatible, it is thought that favorable adhesiveness is implement | achieved.

  The PPE in this embodiment is present in a solvent which will be described later, dissolved or absorbed in the solvent and swollen. The solvent used in the mixed liquid of this embodiment has at least one compound (A) selected from compounds having the characteristics of the PPE solvent retention described later, and the solvent retention characteristics of the PPE described later; It is a mixture with one or more compounds (B) selected from compounds having a ring structure in the molecule.

  The solvent retention amount of PPE with respect to the compound (A) is 1500% by mass or more. Moreover, the solvent holding | maintenance amount of PPE with respect to a compound (B) is 300 to 1500 mass%.

In the present disclosure, the solvent retention amount for each compound of PPE is a value determined by the following method. About 80 g of a compound to be measured at 23 ° C. ± 2 ° C. is added to PPE, W0 (g) (provided 5 ± 0.1 g) selected as desired in the present invention. Stir in a thermostatic chamber with a magnetic stirrer for 2 hours or more to obtain a mixture. The obtained mixed solution is transferred to a 100 cm ³ sedimentation tube, and the mixed solution is lightly and uniformly stirred, and then left to stand in a thermostatic chamber at 23 ° C. ± 2 ° C. for 24 hours. The mixed solution is phase-separated into two upper and lower layers. The supernatant liquid is removed, and the mass W of the lower layer (which includes PPE and the solvent retained by PPE) is measured.

From the mass W0 of the above PPE and the mass W that is the sum of the PPE and the solvent held by the PPE, the following formula:
Solvent retention amount (%) = 100 × (W−W0) / W0
Obtain the amount of solvent retained.

  In addition, after the 24 hours of standing, if the solution is a uniform solution or mixed solution without being separated into two upper and lower layers, the solvent holding amount is set to 1600% by mass or more.

  Mixing mass ratio (A) of the compound (A) having a PPE solvent retention of 1500% by mass or more and the compound (B) having a PPE solvent retention of 300% by mass to less than 1500% by mass and having a ring structure in the molecule ): (B) is preferably in the range of 90:10 to 10:90, more preferably in the range of 30:70 to 70:30, from the viewpoint of dispersion stability, coating property, and storage stability. Preferably it is in the range of 40:60 to 60:40.

  When the compound (A) is present in the solvent (preferably at the above-mentioned predetermined ratio or more), the PPE takes the solvent into the particles and swells, so that the viscosity increases, the dispersion stability increases, The coating amount (resin content) also increases. Moreover, since PPE melt | dissolved in the solvent and swollen PPE have good affinity, the immersion property to the base material of PPE is stabilized, and uniform coating can be performed. If the swelling property of PPE is insufficient, there is also a problem that PPE is filtered into the base material / glass cloth / woven fabric structure in the varnish impregnation step and deposited on the impregnation roll. When the compound (A) in the solvent is present at a predetermined ratio or less, the gelation / solidification due to the swelling of PPE can be suppressed, coating can be performed, the swelling / gelation with time can be suppressed, and the storage stability can be improved. It is good.

  In addition, the presence of the compound (B) having a ring structure in the molecule having a solvent holding amount of PPE of 300% by mass or more and less than 1500% by mass (preferably at the above-mentioned predetermined ratio or more) causes the drying of the prepreg. Since it can suppress that a solvent remains in a resin film at a process, even when it makes a coating film thickness thick, it becomes difficult to crack a resin film, and it is preferable from a viewpoint of coating property. In addition, it is presumed that molecular chains on the surface of PPE particles in which PPE is dissolved or swollen are loosened, but the adhesion of PPE particles is improved. Adhesiveness between the base material and the resin component of the prepreg and a cured product produced by heating and pressing the prepreg is improved. Further, when the compound (B) in the solvent is present in the predetermined ratio or less, the advantage can be obtained when the compound (A) is present in the predetermined ratio or more. The compound (B) has a ring structure in the molecule from the viewpoint of dissolving or swelling PPE for the reasons described later. The ring structure can be, for example, an aromatic ring and an alicyclic ring. The solvent holding | maintenance amount of PPE with respect to a compound (B) is 300 mass%-less than 1500 mass%, Preferably it is 300 mass%-1000 mass%.

  When the compound (A) is used in a large amount exceeding the predetermined ratio, the solvent retention amount of PPE in the mixed solution becomes high, and the property of retaining the solvent in the resin film in the drying process at the time of manufacturing the prepreg becomes strong. . Thereby, the drying inside the resin film is difficult to proceed, and as a result, there is a tendency that the possibility of causing cracks is increased. In addition, when the resin film thickness is increased, cracks tend to become more prominent, and the thickness of the resin film tends to be limited. Moreover, when using a compound (B) in large quantities exceeding the said predetermined ratio, the solvent retention amount of PPE in a liquid mixture falls, and there exists a tendency for dispersion stability to fall, such as precipitation of PPE during coating. is there.

  Here, the compound (A) having a PPE solvent holding amount of 1500% by mass or more is not particularly limited, but the organic solvent having an aromatic ring as a ring structure is not limited to the type and molecular weight of PPE. Since it tends to be 1500 mass% or more, it is preferably used. As a preferable example, benzene, toluene, xylene, etc. can also be used independently, and 2 or more types can also be mixed and used. As another example, chloroform or the like can be used.

  Further, the compound (B) having a ring structure in the molecule where the solvent holding amount of PPE is 300% by mass or more and less than 1500% by mass is not particularly limited, but preferably has a boiling point higher than that of the compound (A), Furthermore, it is more preferable that the boiling point is 18 ° C. or higher than the compound (A), and it is more preferable that the boiling point is 25 ° C. or higher than the compound (A). By providing such a difference in boiling points, the compound (A) having a high PPE solvent retention amount is likely to volatilize faster than the compound (B) in the drying step during the production of the prepreg. Accordingly, when the prepreg is produced, the remaining amount of the compound (A) that is easily held by the PPE in the resin film in the drying step can be reduced, and thus a mixed solution having more excellent coatability can be obtained. Moreover, if the difference in boiling point between the compound (A) and the compound (B) is 18 ° C. or more, the film formability can be further improved. On the other hand, when the difference between the boiling points of the compound (A) and the compound (B) is too large, the film formation quality (resin film) due to rapid volatilization of the compound (A) is suppressed while suppressing the remaining of the compound (B) in the prepreg. The compound (B) has a boiling point that is preferably 60 ° C. or less, more preferably 50 ° C. or less, higher than that of the compound (A), since it is difficult to achieve a balance of suppressing a decrease in the occurrence of unevenness on the surface. In addition, when the compound (A) contains two or more kinds of compounds, the number average value calculated based on the value obtained by multiplying the content ratio of each compound in the compound (A) by the respective boiling point is the compound (A ) Boiling point. The same applies to compound (B).

  The ring structure possessed by the compound (B) is preferably from a 4-membered ring to an 8-membered ring, and among these, ketones, alkenes and the like are particularly preferable. Since these have a ring structure and a double bond in the molecule, the molecular structure is close to the molecular structure of PPE. Therefore, the swelling property or solubility of PPE by these compounds is relatively high, and it is presumed that the solvent retention amount of PPE with respect to these compounds increases. As a preferable example, cyclohexanone, cyclopentanone, cyclohexene or the like can be used alone, or two or more kinds can be mixed and used.

  The mixed liquid of this embodiment can contain, for example, a cross-linkable curable resin, an additional resin, various additives, and the like.

  The mixed liquid of this embodiment preferably further contains a crosslinkable curable resin, more preferably a crosslinkable curable resin and an initiator. The content of the crosslinkable curable resin is preferably 5 to 95 parts by mass, more preferably 10 to 80 parts by mass, and still more preferably 10 to 70 parts by mass with respect to 100 parts by mass in total of PPE and the crosslinkable curable resin. It is 20 mass parts, More preferably, it is 20-70 mass parts. When the content is 5 parts by mass or more, it is preferable in terms of good moldability, and when it is 95 parts by mass or less, it is preferable in that a cured product having a low dielectric constant and dielectric loss tangent can be formed.

  As the crosslinkable curable resin, a monomer having two or more vinyl groups in the molecule is suitable, and triallyl isocyanurate (TAIC), triallyl cyanurate, triallylamine, triallyl mesate, divinylbenzene, divinyl Naphthalene, divinylbiphenyl and the like can be mentioned, and among them, TAIC having good compatibility with polyphenylene ether is preferable.

  As the initiator, any initiator having the ability to promote the polymerization reaction of the vinyl monomer can be used. For example, benzoyl peroxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, di-t-butyl peroxide, t-butylcumyl peroxide, α, α'-bis (t-butylperoxy) -M-isopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dicumyl peroxide, di-t-butylperoxyisophthalate, t-butylperoxybenzoate, 2 , 2-bis (t-butylperoxy) butane, 2,2-bis (t-butylperoxy) octane, 2,5-dimethyl And peroxides such as ru-2,5-di (benzoylperoxy) hexane, di (trimethylsilyl) peroxide, and trimethylsilyltriphenylsilyl peroxide. A radical generator such as 2,3-dimethyl-2,3-diphenylbutane can also be used as a reaction initiator. Among these, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne is preferred from the viewpoint of providing a cured product having excellent heat resistance and mechanical properties and having a lower dielectric constant and dielectric loss tangent. -3, α, α'-bis (t-butylperoxy-m-isopropyl) benzene and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane are preferred.

  From the viewpoint of increasing the reaction rate, the initiator content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, with respect to a total of 100 parts by mass of PPE and the crosslinkable curable resin. Preferably, it is 1.5 parts by mass or more, and preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 7 parts by mass from the viewpoint that the dielectric constant and dielectric loss tangent of the obtained cured product can be kept low. Or less.

  In a preferred embodiment, the content of the crosslinkable curable resin is 10 parts by mass or more and 70 parts by mass or less, and the content of the initiator is 1 part by mass with respect to a total of 100 parts by mass of PPE and the crosslinkable curable resin. The amount is 10 parts by mass or less.

  The mixed liquid of this aspect may further contain an additional resin (for example, a thermoplastic resin, a curable resin, etc.). Thermoplastic resins include ethylene, propylene, butadiene, isoprene, styrene, divinylbenzene, methacrylic acid, acrylic acid, methacrylic ester, acrylic ester, vinyl chloride, acrylonitrile, maleic anhydride, vinyl acetate, ethylene tetrafluoride, etc. Examples thereof include homopolymers of vinyl compounds and copolymers of two or more vinyl compounds, and polyamides, polyimides, polycarbonates, polyesters, polyacetals, polyphenylene sulfides, polyethylene glycols, and the like. Among these, a styrene homopolymer, a styrene-butadiene copolymer, and a styrene-ethylene-butadiene copolymer can be preferably used from the viewpoints of solubility in a solvent and moldability. Examples of the curable resin include phenol resins, epoxy resins, and cyanate esters. The thermoplastic resin and curable resin may be modified with a functional compound such as an acid anhydride, an epoxy compound, or an amine. The amount of such additional resin used is preferably 10 to 90 parts by mass, more preferably 20 to 70 parts by mass with respect to 100 parts by mass in total of the PPE and the crosslinkable curable resin.

  The mixed solution may further contain an appropriate additive depending on the purpose. Examples of the additive include a flame retardant, a heat stabilizer, an antioxidant, a UV absorber, a surfactant, a lubricant, a filler, and a polymer additive.

  In particular, when the mixed solution further contains a flame retardant, the moldability, water absorption resistance, solder heat resistance, and adhesiveness (for example, the peel strength between layers in a multilayer board or the peel strength between a cured product and copper foil, etc.) In addition to the advantage that an excellent printed wiring board and the like can be obtained, it is preferable in that flame retardancy can be imparted.

  The flame retardant is not particularly limited as long as it has a function of inhibiting the combustion mechanism. Inorganic flame retardants such as antimony trioxide, aluminum hydroxide, magnesium hydroxide and zinc borate, hexabromobenzene, decabromobenzene And aromatic bromine compounds such as phenylethane, 4,4-diphbromophenyl, and ethylenebistetrabromophthalimide. Of these, decabromojephenylethane is preferred from the viewpoint of keeping the dielectric constant and dielectric loss tangent of the cured product low.

  The amount of flame retardant used varies depending on the flame retardant used, and is not particularly limited. From the viewpoint of maintaining flame retardancy at the UL standard 94V-0 level, a total of 100 parts by mass of PPE and the crosslinkable curable resin Is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 15 parts by mass or more. Moreover, from a viewpoint which can maintain the dielectric constant and dielectric loss tangent of the hardened | cured material small, Preferably it is 50 mass parts or less, More preferably, it is 45 mass parts or less, More preferably, it is 40 mass parts or less.

[Production of liquid mixture containing PPE and solvent]
The method for producing the mixed solution is not particularly limited as long as the PPE contained in the mixed solution satisfies the requirements of the present invention. For example, PPE is dispersed in a solvent, or PPE is pulverized in the solvent. And a method in which PPE having a predetermined particle size is dispersed (hereinafter also referred to as “crush dispersion method”).

  The particle size of PPE present in the mixed solution, the PPE content ratio in the mixed solution, and the PPE molecular weight can be adjusted by adjusting in advance the PPE to be added to the solvent, for example, in the “crush dispersion method” described later. Or, it can be adjusted by changing the crushing strength in the solvent or the solvent used.

[Crushing dispersion method]
Examples of the method of dispersing PPE in a solvent or pulverizing PPE in a solvent to form a state in which PPE having a predetermined particle size is dispersed include the following two methods.
(1) Method for Dispersing PPE with Adjusted Particle Size in Solvent As a method for adjusting particle size, wet or dry pulverization and sieving can be mentioned. These methods may be combined.
□ The solvent to be used is not particularly limited, but the above-mentioned compound (A) and compound (B) are used in a mixing ratio in which the mass ratio (A) :( B) is 90:10 to 10:90. It is preferable. In this case, while ensuring the fluidity and dispersion stability of PPE, it is possible to obtain a prepreg excellent in the coating property to the substrate and excellent in the adhesion between the substrate and the curable resin composition containing PPE particles. Therefore, it is preferable. Among the compounds (A), aromatic organic solvents such as benzene, toluene, and xylene are preferable, and these may be used alone or in admixture of two or more. Among the compounds (B), ketones such as cyclohexanone and cyclopentanone and alkenes such as cyclohexene are preferable, and these may be used alone or in combination of two or more. These solvents can be selected and used in a timely manner according to the PPE used.

(2) A method for preparing a mixed solution in which PPE is crushed in a solvent and PPE is dispersed in the solvent. □ The solvent to be used is not particularly limited, but the compound (A) and the compound (B) are: The mass ratio (A) :( B) is preferably used at a mixing ratio of 90:10 to 10:90. In this case, while ensuring the fluidity and dispersion stability of PPE, it is possible to obtain a prepreg excellent in the coating property to the substrate and excellent in the adhesion between the substrate and the curable resin composition containing PPE. preferable. Among the compounds (A), aromatic organic solvents such as benzene, toluene, and xylene are preferable, and these may be used alone or in admixture of two or more. Among the compounds (B), ketones such as cyclohexanone and cyclopentanone and alkenes such as cyclohexene are preferable, and these may be used alone or in combination of two or more. These solvents can be selected and used in a timely manner according to the PPE used.

  The method for obtaining a mixed solution in which PPE is dispersed is not particularly limited as long as the PPE contained in the obtained mixed solution satisfies the requirements of the present invention, but after mixing PPE and a solvent, other methods are used. Examples thereof include a method of obtaining a mixed solution by adding components, and a method of obtaining a mixed solution by adding PPE after other components are first mixed in a solvent.

<Resin varnish>
Another aspect of the present invention provides a resin varnish containing the liquid mixture according to one aspect of the present invention described above. The resin varnish may typically be the above-mentioned mixed solution, or may be a solution obtained by further adding other components to the mixed solution. For example, after preparing a liquid mixture containing only PPE and a solvent, other components may be added to prepare a resin varnish. As other components in this case, at least one of the aforementioned cross-linkable curable resin, additional resin, various additives and the like may be included as a component of the mixed solution.

<Prepreg>
Another aspect of the present invention is obtained by applying a resin varnish containing the mixed liquid according to one aspect of the present invention described above to a base material, and then removing the solvent from the base material by, for example, a hot cloth drier or the like. Provided prepreg.

  As the base material, various glass cloths such as roving cloth, cloth, chopped mat, and surfacing mat; asbestos cloth, metal fiber cloth, and other synthetic or natural inorganic fiber cloth; wholly aromatic polyamide fiber, wholly aromatic polyester fiber Woven or non-woven fabrics obtained from liquid crystal fibers such as polybenzoxazole fibers; natural fiber fabrics such as cotton cloth, linen cloth and felt; carbon fiber cloth, kraft paper, cotton paper, cloth obtained from paper-glass mixed yarn, etc. Natural cellulose base materials; polytetrafluoroethylene porous films; etc. can be used alone or in combination of two or more.

  The proportion of the solid content in the resin varnish in the prepreg (hereinafter also referred to as resin content) is preferably 30 to 80% by mass, more preferably 40 to 70% with respect to 100% by mass of the total amount of prepreg. % By mass. When the resin content is 30% by mass or more, excellent insulation reliability is obtained when the prepreg is used, for example, for forming an electronic substrate, and when it is 80% by mass or less, for example, the obtained electronic substrate is obtained. Is excellent in mechanical properties such as flexural modulus.

<Laminated plate>
Using the mixed liquid according to one embodiment of the present invention, a laminated plate in which a cured product composite and a metal foil are laminated can be formed. The cured product laminate includes a cured product of a curable resin composition obtained by removing the solvent from the resin varnish and a substrate. The laminate is preferably one in which the cured product composite and the metal foil are in close contact with each other, and is suitably used as a material for an electronic substrate. As the metal foil, for example, an aluminum foil and a copper foil can be used, and among them, the copper foil is preferable because of its low electric resistance. The cured product composite to be combined with the metal foil may be one sheet or a plurality of sheets, and the metal foil is laminated on one side or both sides of the cured product composite and processed into a laminate according to the application. As a manufacturing method of a laminated board, for example, a composite (for example, the above-mentioned prepreg) composed of a curable resin composition and a substrate is formed, and this is overlapped with a metal foil, and then a curable resin composition. The method of obtaining the laminated board on which the hardened | cured material laminated body and metal foil are laminated | stacked by hardening | curing is mentioned. One particularly preferred application of the laminate is a printed wiring board.

<Printed wiring board>
Another aspect of the present invention provides a printed wiring board produced using the prepreg according to one aspect of the present invention described above as a constituent component. The printed wiring board of this aspect can be typically formed by pressure heating molding using the prepreg according to one aspect of the present invention described above. Examples of the substrate include the same materials as described above with respect to the prepreg. The printed wiring board of this aspect can have excellent insulation reliability and mechanical properties by being formed using the prepreg as described above.

  Hereinafter, the present embodiment will be specifically described by way of examples. However, the present embodiment is not limited to the following examples.

The physical properties in the following examples, comparative examples and test examples were measured by the following methods.
(1) Number average molecular weight of PPE Using gel permeation chromatography analysis (GPC), the number average molecular weight was determined by comparison with the elution time of standard polystyrene having a known molecular weight.
HLC-8220GPC (manufactured by Tosoh Corporation) is used as a measuring apparatus, and measurement is performed under the conditions of column: Shodex LF-804 × 2 (manufactured by Showa Denko KK), eluent: chloroform at 50 ° C., detector: RI. went.

(2) Solvent retention amount of PPE PPE (S203A, Asahi Kasei Chemicals, number average molecular weight 10,000) and (S202A, Asahi Kasei Chemicals, number average molecular weight 18,000), (S203A, Asahi Kasei Chemicals, number average molecular weight 10) 5,000: pulverized to a particle size of 250 μm or less) Each 5 g was added to 80 g of each of the following compounds, stirred for 2 hours with a stirrer, and allowed to stand at 23 ° C. for 1 day. In the case where the mixed solution was separated into a supernatant and a sediment, the supernatant was removed, the mass of the sediment was measured, and the solvent retention of PPE with respect to each solvent was measured. The compounds used as the solvent were toluene, xylene, cyclohexanone, cyclopentanone, cyclohexene, methyl ethyl ketone, and methanol.

(3) Viscosity of liquid mixture B-type viscometer, rotor No. 3 was used, and the viscosity was measured under the conditions of 23 ° C., 30 rpm, and 30 seconds.
(4) Dispersion stability of the mixed solution 35 g of the mixed solution was placed in a glass 50 ml sample tube and allowed to stand in a thermostatic chamber at 23 ° C. for 3 days. A sample having no separation due to sedimentation or the like of PPE and retaining fluidity was designated as “◯”. In addition, the case where separation due to sedimentation or the like of PPE occurred was evaluated as “x”, and the case where there was no fluidity was evaluated as “gelation”.

(5) Prepreg film formability (cracking)
The appearance of the prepreg was visually confirmed, and the resin composition layer was evaluated as “◯” when there was no crack or the like, and “X” when there was a crack.
(6) Prepreg film-forming properties (powder removal)
When the prepreg was bent at 180 °, it was examined and evaluated whether resin powder fall or resin peeling occurred. First, the prepreg was cut out to a size of 200 mm × 300 mm using a cutter blade. Next, the prepreg was bent at 180 ° so that the two long sides of the rectangle overlapped, and then returned to its original state. Next, the prepreg was bent at 180 ° so that the two sides of the short side of the rectangle overlapped, and then returned to its original state. In the above-mentioned series of prepreg handling, the case where there was no problem in resin powder dropping was evaluated as “◯”, and the case where the resin powder falling off was slightly confirmed although it was not a large problem in handling was evaluated as “△”. On the other hand, those with severe powder fall were rated as “x”.

(7) Dielectric constant and dielectric loss tangent of laminated plate The dielectric constant and dielectric loss tangent of the laminated plate at 1 GHz were measured using an impedance analyzer.
Using an impedance analyzer (4291B op.002 with 16453A, 16454A, manufactured by Agilent Technologies) as a measuring device, measurement is performed under the conditions of a specimen thickness: about 2 mm, voltage: 100 mV, frequency: 1 mm Hz to 1.8 GHz, and the number of sweeps is 100. It calculated | required as an average value of times.
(8) Water Absorption Rate of Laminate Plate The laminate plate was subjected to a water absorption acceleration test, and the water absorption rate was determined from the increased mass.
The laminate was cut into 50 mm squares to produce test pieces. After the test piece was dried at 130 ° C. for 30 minutes, the mass was measured to obtain the mass (g) before the acceleration test. Subsequently, the mass after the acceleration test was performed under the conditions of temperature: 121 ° C., pressure: 2 atm, and time: 4 hours, and the mass (g) after the acceleration test was measured.
Using the mass (g) before the acceleration test and the mass (g) after the acceleration test, the following formula:
Water absorption (mass%) = (mass before acceleration test−mass after acceleration test) / mass before acceleration test × 100
Then, the water absorption was calculated, and the average value of the measured values of the four test pieces was obtained.

(9) Solder heat resistance after water absorption test of laminated board A solder heat resistance test at 288 ° C was performed using the laminated board after measuring the water absorption rate described in (8) above. The laminated board after the water absorption acceleration test was immersed in a solder bath at 288 ° C. for 20 seconds, and visually observed. A laminated board in which no swelling, peeling or whitening was confirmed even when immersed in a solder bath was evaluated as “◯”. Moreover, the laminated board in which any one or more of swelling, peeling, and whitening was generated by immersion in a solder bath was evaluated as “x”.
(10) Copper foil peel strength of laminate (peel strength N / mm)
The stress when peeling the copper foil of the copper clad laminate at a constant speed was measured. A copper-clad laminate using a 35 μm copper foil (GTS-MP foil, manufactured by Furukawa Electric Co., Ltd.) produced by the method described below was cut into a size of 15 mm wide × 150 mm long, and an autograph (AG-5000D, Shimadzu Corporation) was used to measure the average value of the load when the copper foil was peeled off at a speed of 50 mm / min at an angle of 90 ° C. with respect to the removal surface, and the average value of five measurements was obtained. .

(11) Residual solvent of prepreg The amount of solvent remaining in the prepreg was measured by gas chromatography. 6 g of the collected prepreg was added to 50 ml of chloroform, and stirred with a magnetic stirrer for 2 hours. Then, it was left still for one day, and insoluble matter was filtered with a Kiriyama funnel while washing with chloroform to obtain a 200 ml sample extract. The sample extract was gas chromatograph (GC-1700, manufactured by Shimadzu Corporation) using hexadecane as an internal standard sample, a hydrogen flame ionization detector as a detector, polydimethylsiloxane as a stationary phase, and a carrier. Using helium as the gas, the amount of residual solvent was measured.

<Production Example 1>
A 10 L flask was placed in an oil bath heated to 90 ° C., and nitrogen gas was introduced into the flask at a rate of 30 ml per minute. Thereafter, the operation was always performed under a nitrogen gas stream. To this, 1000 g of PPE (S202A, manufactured by Asahi Kasei Chemicals, number average molecular weight 18,000) and 3000 g of toluene were added and dissolved by stirring. Further, a solution obtained by dissolving 80 g of bisphenol A in 350 g of methanol was added to the flask with stirring. After stirring for 5 minutes, 3 ml of 6 mass% cobalt naphthenate mineral spirit solution was added with a syringe, and stirring was continued for 5 minutes. Next, 1125 g of toluene was added to 375 g of the benzoyl peroxide solution, and a solution diluted so that the benzoyl peroxide concentration was 10% by mass was placed in a dropping funnel and dropped into the flask over 2 hours. After completion of the dropwise addition, heating and stirring were further continued for 2 hours to obtain a reaction solution containing a low molecular weight PPE.

  Next, after adding 3000 g of water and stirring for 5 minutes, the reaction solution was allowed to stand, and after two layers were separated, the lower tank was removed. Further, 1000 g of water was added, stirred, allowed to stand, and again separated into two tanks, and then the lower tank was removed. Next, 200 g of methanol was added, and the mixture was stirred and allowed to stand in the same manner to be separated into two layers, and then the upper layer was removed. Further, 100 g of methanol was added, and similarly stirred and allowed to stand to separate into two layers. Then, the lower layer was recovered, and a large amount of methanol was added thereto to precipitate low molecular weight PPE, which was filtered and dried. Molecular weight PPE was obtained. The number average molecular weight of the obtained low molecular weight PPE was 2800.

<Test Example 1>
The solvent retention of each PPE was measured for each compound constituting the solvent in the following examples and comparative examples, and the results are shown in Table 1.

<Example 1>
50 parts by mass of toluene was placed in a SUS container, and 4.5 parts by mass of a styrene elastomer (SEBS, manufactured by Asahi Kasei Chemicals, H1041 grade) was added and dissolved. For this solution, 50 parts by mass of cyclohexanone, 17.2 parts by mass of triallyl isocyanurate (Nihon Kasei), α, α′-bis (t-butylperoxy-m-isopropyl) benzene (perbutyl P, JP Oil) 1.0 parts by mass, and after stirring uniformly, decabromodiphenylethane (SAYTEX 8010, Albemarle Japan) 12.2 parts by mass, silica filler (spherical silica, made by Tatsumori) 33 parts by mass, After uniformly stirring, while stirring with a 75 mm diameter cross paddle blade at a tip speed of 1.0 m / min, the particle size was adjusted in advance by pulverization so that the particle size was adjusted to 250 μm or less. S203A, manufactured by Asahi Kasei Chemicals Co., Ltd., number average molecular weight 10,000) 32 parts by mass is added and stirred for 3 hours so that the whole becomes uniform. Is a 2mPa · s, dispersion stability, which was confirmed by the method described above to obtain a mixed solution of "〇". This mixed solution was used as a coating varnish.

  Next, the coating varnish was impregnated into a 0.1 mm thick E glass glass cloth (2116 style, manufactured by Asahi Schavel), the excess varnish was scraped off with a slit, and dried at 150 ° C. for 2 minutes. A prepreg having a resin content of 55% by mass was obtained.

<Example 2>
A coating varnish having a viscosity of 1255 mPa · s and a dispersion stability of “◯” was obtained in the same manner as in Example 1, except that cyclohexanone was changed to cyclopentanone.
Next, a prepreg having a resin content of 54 mass% was obtained in the same manner as in Example 1 except that the drying temperature was changed to 130 ° C.

<Example 3>
A coating varnish having a viscosity of 1260 mPa · s and a dispersion stability of “◯” was obtained in the same manner as in Example 1, except that cyclohexanone was changed to cyclohexene.
Next, a prepreg having a resin content of 52 mass% was obtained in the same manner as in Example 1 except that the drying temperature was changed to 105 ° C.

<Example 4>
A coating varnish having a viscosity of 1210 mPa · s and a dispersion stability of “◯” was obtained in the same manner as in Example 1 except that toluene was changed to xylene.
Further, a prepreg having a resin content of 55% by mass was obtained in the same manner as in Example 1.

<Example 5>
A coating varnish having a viscosity of 1356 mPa · s and a dispersion stability of “◯” in the same manner as in Example 1 except that PPE is changed to (S202A, manufactured by Asahi Kasei Chemicals, number average molecular weight 18,000). Got.
Further, a prepreg having a resin content of 56% by mass was obtained in the same manner as in Example 1.

<Example 6>
Viscosity is 870 mPa · s in the same manner as in Example 1 except that cyclohexanone is changed to cyclopentanone, the amount of toluene used is 10 parts by mass, and the amount of cyclopentanone is changed to 90 parts by mass. A coating varnish having a dispersion stability of “◯” was obtained.
Next, a prepreg having a resin content of 52 mass% was obtained in the same manner as in Example 1 except that the drying temperature was changed to 130 ° C.

<Example 7>
A viscosity of 978 mPa · s and a dispersion stability of “◯” were applied in the same manner as in Example 6 except that the amount of toluene used was changed to 30 parts by mass and the amount of cyclopentanone used was changed to 70 parts by mass. An industrial varnish was obtained.
Further, a prepreg having a resin content of 53 mass% was obtained in the same manner as in Example 6.

<Example 8>
A viscosity of 1415 mPa · s and a dispersion stability of “◯” were applied in the same manner as in Example 6 except that the amount of toluene used was changed to 70 parts by mass and the amount of cyclopentanone used was changed to 30 parts by mass. An industrial varnish was obtained.
Further, a prepreg having a resin content of 54 mass% was obtained in the same manner as in Example 6.

<Example 9>
A viscosity of 1921 mPa · s and a dispersion stability of “◯” were applied in the same manner as in Example 6 except that the amount of toluene used was changed to 90 parts by mass and the amount of cyclopentanone used was changed to 10 parts by mass. An industrial varnish was obtained.
Further, a prepreg having a resin content of 55% by mass was obtained in the same manner as in Example 6.

<Example 10>
A viscosity of 2313 mPa · s and a dispersion stability of “◯” were applied in the same manner as in Example 6 except that the amount of toluene used was changed to 95 parts by mass and the amount of cyclopentanone used was changed to 5 parts by mass. An industrial varnish was obtained.
Further, a prepreg having a resin content of 55% by mass was obtained in the same manner as in Example 6.

<Example 11>
A viscosity of 578 mPa · s and a dispersion stability of “◯” were applied in the same manner as in Example 6 except that the amount of toluene used was changed to 5 parts by mass and the amount of cyclopentanone was changed to 95 parts by mass. An industrial varnish was obtained.
Further, a prepreg having a resin content of 51% by mass was obtained in the same manner as in Example 6.

<Comparative Example 1>
A varnish was prepared in the same manner as in Example 1 except that the amount of toluene used was changed to 100 parts by mass without using cyclohexanone. Since the fluidity was lost and the solution was "gelled", a varnish that could be used for coating could not be obtained.

<Comparative Example 2>
The viscosity is 340 mPa · s and the dispersion stability is the same as in Example 1, except that toluene is not used, cyclohexanone is changed to cyclopentanone, and the amount used is changed to 100 parts by mass. Prepared “×” varnish. It is presumed that the dispersion stability was poor, but during the preparation of the prepreg, precipitation of solids in the varnish bath and accumulation of solids on the impregnation roll occurred, and a prepreg of quality that can be used for later evaluation can be obtained. There wasn't.

<Comparative Example 3>
A varnish having a viscosity of 450 mPa · s and a dispersion stability of “×” was prepared in the same manner as in Example 1 except that cyclohexanone was changed to methyl ethyl ketone. It is presumed that the dispersion stability was poor, but during the preparation of the prepreg, precipitation of solids in the varnish bath and accumulation of solids on the impregnation roll occurred, and a prepreg of quality that can be used for later evaluation can be obtained. There wasn't.

<Comparative Example 4>
The viscosity is 1818 mPa · s in the same manner as in Example 1 except that the amount of toluene used is changed to 95 parts by mass, cyclohexanone is changed to methanol, and the amount used is changed to 5 parts by mass. A coating varnish having a property of “◯” was obtained. A prepreg having a resin content of 58% by mass was obtained in the same manner as in Example 1 except that the drying temperature was changed to 105 ° C. When the obtained prepreg was observed, many cracks were confirmed in the resin layer.

<Comparative Example 5>
The viscosity is 2215 mPa · s and the dispersion stability is “◯” in the same manner as in Example 1 except that PPE is changed to low molecular weight PPE (number average molecular weight 2800) and cyclohexanone is changed to cyclopentanone. A varnish for coating was obtained. A prepreg having a resin content of 56% by mass was obtained in the same manner as in Example 1 except that the drying temperature was changed to 130 ° C.

<Test Example 2>
Using the prepregs obtained from Example 1 to Example 11, Comparative Example 4, and Comparative Example 5, the film formability (cracking and powder falling) was evaluated. In Examples 1 to 10 and Comparative Example 5, the evaluation was “◯”. In Example 11, the evaluation of cracking was “△”, although the evaluation of cracking was “◯”. It was confirmed that there was. On the other hand, in Comparative Example 4, the evaluation of cracking was “x”, and the evaluation of powder falling was “◯”.
However, in Comparative Example 5, tackiness considered to be caused by the residual solvent described later was generated, and the handling property during storage was not good.

<Test Example 3>
Using the prepregs obtained from Example 1 to Example 11, Comparative Example 4, and Comparative Example 5, the amount of residual solvent was measured (measurement results are listed in Table 2). From Example 1 to Example 11, the residual amount of solvent was kept low, while in Comparative Example 5, it was confirmed that a large amount of solvent remained.

<Test Example 4>
Substrate samples were prepared using the prepregs obtained in Examples 1 to 11, and electrical characteristics (dielectric constant, dielectric loss tangent), water absorption, solder heat resistance after water absorption test, and copper foil peel strength were compared and evaluated.

A sample for evaluating the water absorption rate and the solder heat resistance after the water absorption test was prepared by the following method. Two prepregs obtained in Examples or Comparative Examples were stacked, and a copper foil (GTS-MP foil, manufactured by Furukawa Electric Co., Ltd.) having a thickness of 12 μm was stacked on the top and bottom. Perform vacuum pressing under conditions of pressure 5 kg / cm ² while heating in minutes, and when reaching 130 ° C., perform vacuum pressing under conditions of pressure 30 kg / cm ² while heating at a rate of temperature increase of 3 ° C./min, up to 200 ° C. When the temperature reached 200 ° C., a double-sided copper-clad laminate was obtained by vacuum pressing under the conditions of a pressure of 30 kg / cm ² and a time of 60 minutes. Next, the copper clad laminate was cut into a 100 mm square, the copper foil was removed by etching, and a sample for evaluating the water absorption rate and the solder heat resistance after the water absorption test was obtained.

Moreover, the sample for copper foil peeling strength measurement was produced with the following method. Two prepregs obtained in Examples or Comparative Examples were stacked, and a copper foil having a thickness of 35 μm (GTS-MP foil, manufactured by Furukawa Electric Co., Ltd.) was stacked on the top and bottom. Perform vacuum pressing under conditions of pressure 5 kg / cm ² while heating in minutes, and when reaching 130 ° C., perform vacuum pressing under conditions of pressure 30 kg / cm ² while heating at a rate of temperature increase of 3 ° C./min, up to 200 ° C. When the temperature reached 200 ° C., a double-sided copper-clad laminate was produced by vacuum pressing under the conditions of a pressure of 30 kg / cm ² and a time of 60 minutes. This double-sided copper-clad laminate was used as a sample for measuring the copper foil peel strength.

A sample for measuring dielectric constant and dielectric loss tangent was prepared by the following method. Sixteen prepregs obtained in Examples or Comparative Examples were stacked, vacuum-pressed under the condition of a pressure of 5 kg / cm ² while heating from room temperature at a heating rate of 3 ° C./min, and when reaching 130 ° C., the heating rate was 3 ° C. By performing vacuum pressing under the condition of pressure 30 kg / cm ² while heating at / min, and when reaching 200 ° C., performing vacuum pressing under the conditions of pressure 30 kg / cm ² and time 60 minutes while maintaining the temperature at 200 ° C. A laminate was prepared. The laminate was cut into a 100 mm square and used as a sample for measuring dielectric constant and dielectric loss tangent.

  As described above, using prepreg, double-sided copper-clad laminate (copper foil: 12 μm and 35 μm), or laminate, copper foil peel strength, dielectric constant, dielectric loss tangent, water absorption, and solder heat resistance after water absorption Sex was measured. The results are shown in Table 2 below.

  The present invention can be suitably applied as a material for a printed wiring board of an electronic device using a high frequency band.

Claims (12)

A mixed solution containing polyphenylene ether and a solvent,
(1) The number average molecular weight of the polyphenylene ether is 5000 to 40000,
(2) The solvent is
A compound (A) that is one or more selected from compounds having a solvent retention of 1500% by mass or more of the polyphenylene ether;
The liquid mixture which is a mixture with the compound (B) which is 1 type or more selected from the compound whose solvent holding | maintenance amount of the said polyphenylene ether is 300 mass% or more and less than 1500 mass%, and has a ring structure in a molecule | numerator.   The liquid mixture according to claim 1, wherein a ratio of the compound (A) to the whole solvent is 10% by mass or more and 90% by mass or less.   The mixed liquid according to claim 1 or 2, wherein the boiling point of the compound (B) is higher than the boiling point of the compound (A).   The mixed liquid according to claim 3, wherein the boiling point of the compound (B) is 18 ° C. or more higher than the boiling point of the compound (A).   The mixed solution according to any one of claims 1 to 4, wherein the ring structure of the compound (B) is a 4-membered ring to an 8-membered ring.   The said compound (B) is a liquid mixture of any one of Claims 1-5 which is a ketone compound or an alkene compound.   The mixed liquid according to claim 1, further comprising a cross-linkable curable resin and an initiator.   The mixed liquid according to claim 7, wherein the crosslinkable curable resin is a monomer having two or more vinyl groups in a molecule.   The mixed liquid according to claim 8, wherein the crosslinkable curable resin is triallyl isocyanurate (TAIC).   The resin varnish containing the liquid mixture of any one of Claims 1-9.   The prepreg obtained by apply | coating the resin varnish containing the liquid mixture of any one of Claims 1-9 to a base material, and then removing a solvent from the said base material.   A printed wiring board produced using the prepreg according to claim 11 as a constituent component.