JPS63224906A - Manufacture of prepreg - Google Patents

Abstract

PURPOSE:To prevent generation of a void, by a method wherein at the time of impregnation treatment of a polyphenylene oxide resin composition with a crosslinking monomer in two stages, an inorganic filler is compounded with the same by a predetermined quantity at the first stage. CONSTITUTION:A base material is impregnated with a polyphenylene oxide resin composition containing at least a crosslinking monomer out of polyphenylene oxide, the crosslinking monomer and a crosslinking polymer shown in the formula I and an inorganic filler by separating in two stages. As a first impregnating solution contains the crosslinking monomer exceeding half of the quantity of a predetermined quantity of the same, the monomer of a low molecular weight is apt to be impregnated more within the base material, and increase residual resinous contents. As an iorganic filler is compounded whose impregnation quantity exceeds half of the predetermined quantity which is to be compounded, plenty of the inorganic filler is contained within the base material and generation of a void can be prevented.

Description

[Detailed description of the invention] 〔Technical field〕 This invention relates to a method for manufacturing prepreg.

[Background technology]

Polyphenylene oxide has high frequency characteristics (dielectric characteristics)
It has attracted attention in recent years due to its excellent properties. There are various uses for polyphenylene oxide, and for example, there are uses for electronic materials.

When used in electronic material applications, it is particularly conceivable to use it in laminates for printed circuit board layers. Laminated plates are desired to have improved physical properties such as dimensional stability, heat resistance, and solvent resistance. Therefore, attempts have been made to improve the physical properties by crosslinking polyphenylene oxide with a crosslinking agent.

On the other hand, among laminates, those made by laminating composite materials in which a base material (for example, a glass base material) is impregnated with resin, so-called prepreg, have also been improved in physical strength.

Incidentally, the prepreg used for such electrical laminates and the like is required to have good compatibility between the resin and the base material, sufficient resin adhesion, and no voids. Prepreg using polyphenylene oxide has a problem in that it has a relatively large number of voids. Laminated boards made using prepregs with many voids have problems in that they have poor water absorption, poor adhesion strength of metal foil (metal layer), and poor solder heat resistance.

[Object of the Invention] In view of the above circumstances, an object of the present invention is to provide a prepreg manufacturing method that can effectively prevent the generation of voids.

[Disclosure of the invention]

In order to achieve the above object, the inventors conducted studies from various angles. We focused on the fact that many voids were generated around the base material during drying, and after further investigation, we found that there was not enough resin remaining in the base material (there were many voids after the solvent evaporated and the resin shrunk). We were able to obtain the knowledge that voids are generated due to the concavity.

Based on this knowledge, we conducted a deeper study and determined that the impregnation was carried out in two stages and that the first impregnating liquid used for the first stage of impregnation contained more than half of the predetermined amount of inorganic filler. They discovered that the occurrence of voids would be reduced by making the material more stable, and was able to complete this invention. In this way, voids are less likely to occur because more of the inorganic filler is impregnated into the base material. This inorganic filler does not shrink when dried, but even after drying,
Since there is no change in the space occupied within the base material, there is no increase in voids within the base material after drying, unlike in the conventional method.

Therefore, this invention provides polyphenylene oxide,
In order to obtain a prepreg in which a base material is impregnated with at least a crosslinkable monomer and a crosslinkable polymer, and a polyphenylene oxide resin composition containing an inorganic filler, impregnation is performed in two stages, and
The gist of the present invention is a prepreg manufacturing method characterized in that the first impregnating liquid used for the first stage impregnation contains more than half of the predetermined amount of the inorganic filler.

The method for manufacturing prepreg according to the present invention will be explained in detail below.

In the prepreg produced by the production method of the present invention, a base material is impregnated with a polyphenylene oxide resin composition containing at least a crosslinkable monomer selected from polyphenylene oxide, a crosslinkable monomer, and a crosslinkable polymer, and an inorganic filler. .

In this invention, impregnation is carried out in two stages as described above.

More than half of the predetermined amount of the inorganic filler is contained in the first impregnating liquid. Therefore, a large amount of inorganic filler is contained in the base material, and as described above, the generation of voids can be prevented.

Impregnation is carried out in two stages, but by adjusting the distribution of each impregnant in the first impregnating liquid and the second impregnating liquid, effects such as further prevention of void generation can be obtained as mentioned above. be.

If the first impregnating liquid contains more than half of the predetermined amount of crosslinking monomer, monomers with lower molecular weights are more easily impregnated into the base material than polymers with higher molecular weights, so the residual resin If the second impregnating liquid that tends to increase the amount of polyphenylene oxide and the optionally added crosslinkable polymer exceeds half of the predetermined amount, the amount of resin that will adhere to the surface of the substrate will increase. When the amount of resin adhered to the surface of the base material is large, the adhesive strength with metal foil is improved.

The first material other than the inorganic filler for the solvent in the first impregnating liquid
The ratio of the total amount of impregnated substances (polyphenylene oxide, cross-linking monomer, cross-linking polymer, initiator, etc.) in the impregnating liquid is greater than the ratio of the total amount of impregnation of both impregnating liquids other than the inorganic filler to the total amount of solvent in both impregnating liquids. It is desirable that the value is also high. In this case, the first impregnating liquid becomes a solution with a high concentration of resin content, the degree of shrinkage of the resin content during drying is reduced, and voids are less likely to occur. At this time, if the distribution ratio of the crosslinking monomer is large, it is easy to impregnate the resin with the impregnating liquid even if the resin concentration is high.

The second impregnation liquid other than the inorganic filler for the solvent
The ratio of the total amount of impregnated substances (polyphenylene oxide, cross-linking monomer, cross-linking polymer, initiator, etc.) in the impregnating liquid is greater than the ratio of the total amount of impregnation of both impregnating liquids other than the inorganic filler to the total amount of solvent in both impregnating liquids. It is desirable that the temperature is also low. In this case, the second impregnating liquid is a solution with a low resin concentration, and it is easy to impregnate the substrate even if it is clogged with the substrate impregnated material to some extent during the first stage of impregnation. At this time, if the distribution ratio of the polyphenylene oxide and the optionally added crosslinkable polymer is large, the amount of resin attached to the surface of the substrate tends to be large.

Next, this invention will be explained in more detail. Polyphenylene oxide (also referred to as polyphenylene ether, hereinafter referred to as "PP0J") used in this invention is, for example, represented by the following general formula, An example thereof is poly(2,6-dimethyl-1,4-phenylene oxide).

Such a ppo is, for example, USP 4059
It can be synthesized by the method disclosed in No. 568. For example, 2,6-xylenol is subjected to an oxidative camping reaction with an oxygen-containing gas and methanol in the presence of a catalyst to produce poly(2,6-dimethyl-1.4
-phenylene oxide), but is not limited to this method. Here, as a catalyst, a copper (I) compound, N,N''-di-tert-butylethylenediamine,
Contains butyldimethylamine and hydrogen bromide. Based on methanol, 2 to 15% by weight of water is added to the reaction mixture system, and the total amount of methanol and water is 5 to 25% by weight.
% by weight of the polymerization solvent. Although not particularly limited, for example, the weight average molecular weight (M w
) is so, ooo, molecular weight distribution M w / M n =
A polymer having a molecular weight of 4.2 (Mn is number average molecular weight) is preferably used.

PPO is a resin with a low dielectric constant and little dielectric loss, so by mixing it with an inorganic filler having a higher dielectric constant, it can be made into a prepreg with any dielectric constant. Also, PP.

is also cheap.

Examples of crosslinking monomers include: ■Acrylates such as ester acrylates, epoxy acrylates, urethane acrylates, ether acrylates, melamine acrylates, alkyd acrylates, and silicone acrylates, ■Triallyl cyanurate, triallyl isocyanate, etc. polyfunctional monomers such as nurate, ethylene glycol dimethacrylate, divinylbenzene, and diallyl phthalate; monofunctional monomers such as vinyltoluene, ethylvinylbenzene, styrene, and paramethylstyrene; and multifunctional epoxies, respectively.
They may be used alone or in combination of two or more, but are not particularly limited to these.

As the crosslinking monomer, it is preferable to use triallyl isocyanurate and/or triallyl cyanurate.
It is good because it has good compatibility with po and is preferable in terms of film formability, crosslinkability, heat resistance, and dielectric properties. Triallyl cyanurate and triallyl isocyanurate are chemically structurally isomers and have similar film-forming properties, compatibility, solubility, reactivity, etc. One or both can be used.

Crosslinking (curing) with crosslinkable monomers and crosslinkable polymers
It has the effect of improving heat resistance etc. without impairing the properties of PO. Crosslinking may be performed using only a crosslinkable monomer, or a crosslinkable polymer may be used in combination. Using them together is more effective in improving characteristics.

Examples of crosslinkable polymers include, but are not limited to, 1,2-polybutadiene, 1,4-polybutadiene, styrene-butadiene copolymers, and modified 1.2-polybutadiene.
-Polybutadiene (maleic-modified, acrylic-modified, epoxy-modified), rubbers, and the like, each of which may be used alone or in combination of two or more. The polymer state may be an elastomer or a rubber, but a high molecular weight rubber state is preferred since it improves film forming properties.

As an inorganic filler, aluminum oxide (＾120°)
, silicon dioxide (SiOl), titanium dioxide (TiO
□), glass fiber, glass chip, glass flake, barium titanate (BaTiOs), lead titanate (Pb
Ti(h), strontium titanate (SrTiOi
), calcium titanate (CaTiOs), magnesium titanate (MgTi(h), barium zirconate (BaZrO3), lead zirconate (PbZrOi)
, KzO-PbO-SiOz glass, and solid solution of lead titanate and lead zirconate (Pb(ZrTi)Os)
Each of them can be used alone or in combination of two or more, but the invention is not limited to these.

The inorganic filler preferably has a size that does not cause any disadvantage to the properties of the prepreg, and is preferably used in the form of fine particles. If the particle size is too small, handling may become difficult, so 0.1 to 20-
(Preferably, the range is about 0°3 to 10.w).

The use of aluminum oxide, titanium dioxide, silica (silicon dioxide), barium titanate, lead titanate, and other well-known dielectric materials with high dielectric constants as inorganic fillers increases the dielectric constant of the resulting prepreg. hand,
It can now be used in applications that require a high dielectric constant. By adjusting the type and amount of dielectric material, it is also possible to adjust the dielectric constant of the prepreg over a wide range. That is, the inorganic filler also works as a dielectric constant adjuster. As long as the purpose is to increase the dielectric constant, other types of fillers with a high dielectric constant may be used instead of inorganic fillers. The upper limit of the blending ratio of the inorganic filler is the point at which undesirable tendencies such as loss of mechanical strength of the prepreg begin to occur.

There is a tendency that when a flake-like material (inorganic material) is used as the inorganic filler, the dimensional stability, solvent resistance, warpage, etc. when made into a laminate or the like are further improved.

Examples of the flaky inorganic filler include glass flakes and mica, each of which may be used alone or in combination of two or more, but is not limited thereto. For example, there are flat pieces of glass such as micro glass flakes manufactured by Nippon Glass Fiber ■ and fine particles of mica such as Dymonite manufactured by Topie Industries ■. From the viewpoint of electrical properties, mica is preferably muscovite. If the flaky inorganic filler is too large, it will tend to settle in the impregnating solution.
Preservability in solution may deteriorate.

In the prepreg using the PPO-based resin composition of the present invention, the flaky inorganic filler plays the role of a skeleton connecting the resins together with the base material to improve strength. It also works to prevent chemicals from entering. Of course, it also contributes to dimensional stability.

In addition, an initiator is usually used in PPO resin compositions. As the initiator, the following two types can be selected depending on whether the PPO resin composition is to be made into an ultraviolet curing type or a thermosetting type, but the initiator is not limited thereto.

Examples of the ultraviolet curing photoinitiator (that is, one that generates radicals when irradiated with ultraviolet light) include benzoin, benzyl, allyldiazonium fluorobaltate, benzyl methyl ketal, 2,2-jethoxyacetophenone, benzoyl isobutyl ether, Examples include p-Lert-butyltrichloroacetophenone, benzyl(0-ethoxycarbonyl)-α-monoxime, biacetyl, acetophenone, benzophenone, Michler's ketone, tetramethylthiuram sulfide, azobisisobutyronitrile, and the like.

As a thermosetting initiator (that is, one that generates radicals by heat), dicumyl peroxide, ter
t-butylcumyl peroxide, benzoyl peroxide, di-tert-butyl peroxide, 2.5
-dimethyl-2,5-di(tert-butylperoxy)hexane-3,2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, α, α'-
Bis(tert-butylperoxy-m-isopropyl)benzene [1°4 (or 1.3)-bis(tert
-butylperoxyisopropyl) also called benzene]
Peroxides such as 1-hydroxycyclohexylphenyledone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane -1-one, 2-chlorothioxanthone, methylbenzoylformate, 4,4-bisdimethylaminobenzophenone (
Michler's ketone), benzoin methyl ether, methyl-0-benzoyl benzoate, α-aziroxime ester, NOF's bistamyl, etc. The initiator is
Each may be used alone or in combination of two or more.

A UV initiator and a thermal initiator may be used in combination.

The blending ratio of the materials explained above is particularly limited.
~80 parts by weight), 1 to 20 parts by weight of the crosslinkable monomer, and 5 to 50 parts by weight (more preferably 5 to 50 parts by weight) of the crosslinkable polymer.
45 parts by weight) and 1 to 80 parts by weight of the inorganic filler.

If the proportion of the crosslinkable monomer or crosslinkable polymer is below the above range, adhesion may become insufficient.
If it exceeds the above range, the characteristics of PPO may not appear. If the proportion of the inorganic filler is below the above range, the effect of adding the inorganic filler may not be achieved, and if it exceeds the above range, the above-mentioned unfavorable tendencies may occur.

The blending ratio of the initiator is preferably 0.1 to 5 parts by weight (more preferably 0.1 to 3 parts by weight). If the ratio of the initiator is below the above range, the PPO resin composition Curing may be insufficient, and if it exceeds the above range, it may adversely affect the physical properties after curing.

The above raw materials are usually dissolved and dispersed in a solvent (solvent) (
Inorganic fillers are usually insoluble) and mixed (solution mixing) before use.

In order to improve the film-forming properties of the PPO resin composition of the present invention, it is preferable to use polystyrene within a range that does not hinder the achievement of the purpose of the present invention. This is desirable from the viewpoint of improving film-forming properties, and when PPO is used in combination with polystyrene and/or styrene-butadiene copolymer, it is preferable to set the blending weight ratio as follows.

Specifically, the impregnation is performed as follows, for example.

After removing the inorganic filler, the raw material of the PPO resin composition is completely dissolved in a solvent at a ratio of, for example, 5 to 50% by weight (preferably 20 to 40% by weight), and then the inorganic filler is added, The base material is immersed (dipped) in this solution to impregnate and adhere these PPO resin compositions to the base material. If the concentration is below the above range, the generation of lipoids with a small residual resin content cannot be sufficiently prevented. When the concentration exceeds the above range, the viscosity of the impregnating solution becomes too high, and the stability and properties of the impregnating solution decrease, making it difficult to impregnate the substrate. After impregnation, remove the solvent by drying.

Examples of solvents include halogenated hydrocarbons such as trichloroethylene, trichloroethane, chloroform, methylene chloride, tetrachloroethylene, and chlorobenzene, benzene,
Aromatic hydrocarbons such as toluene and xylene, acetone,
Examples include carbon tetrachloride, and trichlorethylene is particularly preferred. Multiple types of solvents may be used in combination.

Base materials include resin-impregnated or loss-like materials such as glass cloth, aramid cloth, polyester cloth, loss, and nylon cloth, cloak-like materials made of these materials and/or fibrous materials such as nonwoven fabric, kraft paper, linter paper, etc. paper, etc., but is not limited to these.

Regarding the impregnation method, there are two methods: applying an impregnating liquid to the base material,
There are methods such as immersing the base material in an impregnating liquid. The impregnation time is
Usually, it is about 5 to 60 seconds. Drying conditions vary depending on the type of solvent, but it is preferable to dry for several minutes at a temperature below the boiling point of the solvent and then further dry for several minutes to 10-odd minutes at a temperature above the boiling point.

A laminate using the prepreg obtained according to the present invention (without metal foil on both sides, with metal foil on one side or both sides) can be produced by, for example, combining prepregs produced as follows in a predetermined manner so as to have a predetermined design thickness. If necessary, metal foil is also combined and laminated, and the resin is melted by heating and pressing, etc., and the prepregs and the prepreg and the metal foil are adhered to each other to obtain a laminate.

The conditions for pressing are: temperature: 150-300℃, pressure crab 2
0 to 150 kg/cj, time: about 10 to 60 minutes, but is not limited thereto. Strong adhesion can be obtained by pressing, but even stronger adhesion can be obtained if crosslinking is performed simultaneously with pressing or after pressing, particularly if a crosslinking reaction using a radical initiator is performed by heating. The crosslinking reaction may be carried out by ultraviolet irradiation or the like. When thermal crosslinking and photocrosslinking are not performed, crosslinking by radiation irradiation may be performed. Further, after thermal crosslinking and photocrosslinking, crosslinking by radiation irradiation may be performed. Therefore, adhesion with excellent heat resistance can be achieved between prepregs and between prepregs and metal foil. In addition, at this time, in addition to the prepreg, a sheet made only of PPO resin may be used in combination.

The metal foil and the prepreg may be bonded together using an adhesive.

As the metal foil (metal layer), for example, copper foil.

Metal foil such as aluminum foil is used.

A metal layer may be formed by vapor deposition, or a desired conductor (circuit,
It may be formed as an electrode, etc.), and there is no particular limitation.
- Next, examples and comparative examples of the present invention will be explained.

(Example 1) As a component of the PPO resin composition, PP01 triallyl isocyanurate [TAIC (trade name) of Nippon Kasei ■
], styrene-butadiene copolymer (Toughblane (trade name) from Asahi Kasei Corporation), 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3 [Perhexine 25B (product name) from NOF Corporation name)], average particle size 0.
5-2. crm aluminum oxide (AfxO3) powder was used. A first impregnating liquid and a second impregnating liquid were prepared using these materials in the proportions shown in Table 1.

To make the impregnating liquid, first add anything other than the aluminum oxide powder to the solvent trichlorethylene [Toagosei Chemical Industry ■: Trichloroethylene (trade name)], stir to dissolve and make a uniform solution, and then add the aluminum oxide powder. It was made by dispersing it uniformly using a sand mill.

First, a glass cloth manufactured by Asahi Schniebel (thickness: approximately 100 μm) was immersed in the first impregnating liquid, sufficiently impregnated, and then dried. The drying conditions were 80°C for 3 minutes and 100°C for 3 minutes.

This dried glass cloth was then dipped in the second impregnating liquid, sufficiently impregnated, and then dried to obtain a prepreg.

Drying conditions are 80℃ for 5 minutes, 100℃ for 3 minutes, 160℃
It took 10 minutes. The thickness of the obtained prepreg is approximately 16
It was 0 μm.

Six sheets of prepreg thus obtained were laminated, Cu foil was used as the outermost layer, and pressed at 220° C. and 30 kg/c11 for 30 minutes to obtain a copper-clad laminate.

(Example 2) Ti with an average particle size of 0.5 to 2.0 μm was used as an inorganic filler.
A copper-clad laminate was obtained in the same manner as in Example 1, except that Oz (titanium dioxide) powder was used and the distribution of each component in the first impregnating liquid and the second impregnating liquid was as shown in Table 1.

(Example 3) As an inorganic filler, T with an average particle size of 0.5 to 2.0 μm
Example 1 except that iO, powder was used and the distribution of each component in the first impregnating liquid and the second impregnating liquid was as shown in Table 1.
A copper-clad laminate was obtained in the same manner.

(Example 4) A copper-clad laminate was obtained in the same manner as in Example 1, except that the distribution of each component in the first impregnating liquid and the second impregnating liquid was changed as shown in Table 1.

(Example 5) A copper-clad laminate was obtained in the same manner as in Example 1, except that the distribution of each component in the first impregnating liquid and the second impregnating liquid was changed as shown in Table 1.

(Comparative Example 1.2) A copper-clad laminate was obtained in the same manner as in Example 1, except that the distribution of each component in the first impregnating liquid and the second impregnating liquid was as shown in Table 2.

The solder heat resistance, copper foil peel strength, and water absorption of the copper-clad laminates obtained in Examples 1 to 5 and Comparative Example 1.2 were investigated. The results are shown in Tables 1 and 2.

Almost no voids were observed in the prepregs obtained in Examples 1 to 5. When used as a copper-clad laminate, solder heat resistance,
The properties of copper, foil pulling strength, and water absorption are also determined by the first.
As shown in Table 2, Examples 1 to 5 are superior to Comparative Examples 1 and 2.

The method for producing prepreg according to the present invention is not limited to the above embodiments, and the prepreg produced according to the present invention may be used for other purposes such as flexible printed circuit boards.

〔Effect of the invention〕

Since the prepreg manufacturing method according to the present invention has the above configuration, it is possible to prevent voids from forming in the obtained prepreg. Therefore, laminates and the like produced using this prepreg have excellent properties.

Claims (4)

[Claims] (1) In order to obtain a prepreg in which a base material is impregnated with a polyphenylene oxide resin composition containing at least the crosslinkable monomer of polyphenylene oxide, a crosslinkable monomer, and a crosslinkable polymer, and an inorganic filler, impregnation is carried out in two steps. A prepreg manufacturing method characterized in that the first impregnation liquid used for the first stage impregnation contains more than half of the predetermined amount of the inorganic filler. (2) The method for producing a prepreg according to claim 1, wherein the first impregnating liquid contains more than half of the predetermined amount of the crosslinking monomer. (3) The second impregnating liquid contains more than half of the predetermined amount of polyphenylene oxide and a crosslinkable polymer added as necessary. Prepreg manufacturing method. (4) The ratio of the total amount of impregnants in the first impregnating liquid other than the inorganic filler to the solvent in the first impregnating liquid is In addition, the ratio of the total amount of impregnated substances other than the inorganic filler in the second impregnating liquid to the solvent in the second impregnating liquid is higher than the total amount of impregnated substances other than the inorganic filler in both impregnating liquids to the total amount of solvent in both impregnating liquids. The method for manufacturing a prepreg according to claim 3, wherein the ratio of the total amount of impregnation is lower than the ratio of the total amount of impregnation.