JP2507462B2 - Flame-retardant resin composition and laminated material using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a flame-retardant resin composition and its use, and more particularly to a laminated material suitable for a low dielectric constant multilayer printed board having excellent heat resistance and electrical characteristics. .

[Conventional technology]

Hitherto, a laminate of epoxy resin, polyimide resin, etc. has been used for a long time as a laminate material for a multilayer printed board. However, in recent years, with the increase in the speed of arithmetic processing of a large-scale computer, a printed board having excellent electric characteristics has been demanded in order to improve the signal transmission speed. In particular, there is a need for a high-density multi-layer printed board with a low dielectric constant in order to shorten the signal transmission delay time and the circuit thickness. Currently, a polybutadiene-based material is being developed as a laminated material having a lower dielectric constant, which replaces the polyimide material applied to a large-scale computer (Japanese Patent Publication No. 58-21926). [Problems to be solved by the invention] Currently developed Polybutadiene-based materials that are used have a lower relative permittivity than polyimide materials and are suitable for high-speed signal transmission, but they have problems such as insufficient adhesiveness and mechanical strength during prepreg, and insufficient heat resistance. There are many. In addition, since polybutadiene is a combustible resin as the biggest drawback,
It is necessary to consider flame retardancy. In polybutadiene, a low molecular weight crosslinking type flame retardant is generally used. However, these low-molecular cross-linking flame retardants generally have problems that they have an adverse effect on electrical properties and lower the thermal decomposition initiation temperature which is a measure of heat resistance. Therefore, studies are being conducted on polymer cross-linking flame retardants. Typical examples thereof include alkenyl ethers of poly (p-hydroxybromostyrene) and alkenoyl esters. These have a relatively low relative dielectric constant and are excellent in heat resistance. It is considered that the combination of this flame retardant and the polybutadiene prepolymer makes a laminated material suitable for a low dielectric constant multilayer printed board. However, poly (p-hydroxybromostyrene) with all side chains having unsaturated groups such as alkenyl and alkenoyl, which are reactive groups, causes a heterogeneous reaction in the distance between crosslinking points during thermal crosslinking, resulting in stress during curing reaction. Due to the concentration, the resulting cured product is prone to cracking during heat shock or heat cycle. An object of the present invention is to provide a low dielectric constant flame-retardant laminated material excellent in heat resistance and electric characteristics by using a polymer cross-linking flame retardant capable of obtaining a cured product having a uniform cross-link density without causing stress concentration during a curing reaction. To do.

[Means for solving problems]

The present invention will be outlined. First, the first relates to a flame-retardant resin composition, and the characteristics thereof are represented by the following general formula I (In the formula, R ₁ is a reactive group having an epoxy ring, R ₂ is a reactive group having an unsaturated bond, and m and n are numbers from 1 to 4.
X and Y are copolymerization ratios, both in the range of 0.3 to 0.7,
X + Y = 1 is satisfied. ) Is an essential component of a prepolymer represented by. The second of the present invention relates to a prepreg obtained by impregnating a sheet-shaped base material with a flame-retardant resin composition and drying it, or a material for laminating a multilayer printed board such as a laminated board obtained by laminating and molding the required number of sheets. is there.

In the copolymerized prepolymer represented by the general formula I, Y = 1,
That is, in the case where all the side chains have radical-reactive unsaturated bonds, the concentration of the reactive group locally increases due to the polymer effect in the vicinity of the cross-linking point during heat-crosslinking, and the reaction concentrates.
In other words, when the crosslinking reaction proceeds to some extent, the mobility of the polymer becomes small, and the reaction rate significantly decreases. Therefore, the distance between cross-linking points becomes non-uniform, the cross-linking density of the obtained cured product varies, and residual stress locally concentrates. As a result, cracking is likely to occur due to thermal shock such as heat shock or heat cycle. Therefore, as shown in the general formula I, by uniformly introducing another reactive group having an epoxy ring in the side chain, the radical reaction in the prepolymer is uniformly carried out, and a cured product having a uniform crosslinking density is obtained. We have examined various prepolymers. Furthermore, at this time, the reaction rate is slower than that of the radical reaction, and curing is performed while relaxing the residual stress at the time of curing, and furthermore, by introducing an ionic polymerization epoxy ring with a small curing shrinkage amount, a cured product with less residual stress is obtained. can get. In this way, the crack resistance to thermal shock is greatly improved.

Among the prepolymers which are essential components of the flame-retardant resin composition of the present invention, those represented by the general formula I are ethers and esters of poly (p-hydroxybromostyrene).
Here, the reactive group R ₁ having an epoxy ring includes 1,2-epoxyethoxy, 2,3-epoxypropanoxy, 3,4-epoxybutanoxy, 4- (1,2-epoxyethyl) phenoxy and the like. There is no particular limitation as long as is a reactive group having an epoxy ring. The reactive unsaturated group R ₂ includes alkenyl ether, alkenoyl ester, and the like. Specifically, vinyloxy, isopropenyloxy, isobutenyloxy, allyloxy, acrynoyloxy, methacrynoyloxy, epoxyacrynoyloxy, Epoxy methanoyloxy and the like. The copolymerization ratio of R ₁ and R ₂ is 0.3 to
By using a random copolymer in the range of 0.7, a side chain having a reactive group at an appropriate position can be obtained, and a flame-retardant cured product having a uniform crosslink density during the curing reaction can be obtained.

In addition, 1,2-polybutadiene derivatives having an unsaturated group in the side chain include 1,2-polybutadiene single prepolymer, cyclized 1,2-polybutadiene, epoxy-modified 1,2-polybutadiene, terminal epoxidized 1, 2-polybutadiene, 1,2
-Polybutadiene glycol, 1,2-polybutadienecarboxylic acid, urethane-modified 1,2-polybutadiene, maleated 1,2-polybutadiene, terminal acrylic-modified 1,2-polybutadiene, terminal ester-modified 1,2-polybutadiene, etc.
There are various derivative prepolymers such as polymers and copolymers containing 1,2-polybutadiene having a vinyl group in the side chain as a basic component.

The blending ratio by weight of these two components is selected in the range of 80:20 to 20:80. If the blending amount of the former is larger than this, there is a problem in electrical characteristics and moldability. Further, when the latter compounding amount is large, there are problems in flame retardancy and mechanical strength. Preferably, the compounding ratio of both is 60:40 to 40:60.

Next, a method for manufacturing the laminated material of the present invention will be described.
First, varnish is prepared by dissolving Formula I in an organic solvent at a predetermined concentration. At this time, in order to promote dissolution, it may be heated at an appropriate temperature. Examples of the organic solvent include toluene,
Xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethanol, methanol, 3-methoxypropanol, 2-methoxyethanol, N, N-dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide, trichloroethylene, 1,1,2-trichloroethane, etc. Therefore, any solvent can be used without limitation as long as it can dissolve or mix the component polymers uniformly. A radical polymerization initiator and an epoxy curing agent are added to the prepared varnish to prepare an impregnating varnish. Typical examples of radical polymerization initiators are benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, t-
Butyl perbenzoate, t-butyl peroxylaurate, di-t-butyl peroxyphthalate, dibenzyl peroxide, 2,5-cimethyl-2,5-di (t-butyl peroxy) hexyne-3, cumene hydro Examples include peroxide, t-butyl hydroperoxide, and 2,5-dimethylhexane-2,5-dihydroperoxide. 0.1 to 10 parts by weight is added to 100 parts by weight of the resin composition. As the epoxy curing agent, a generally used curing agent is added in an equivalent or appropriate amount. Examples of the curing agent include aliphatic amines, aromatic amines, secondary and tertiary amines, acid anhydrides, polyamide resins, polysulfide resins and boron trifluoride.
Examples include amine complexes, phenol resins, and dicyandiamide.

In addition, radicals, reaction regulators such as accelerators and inhibitors of epoxy reactions, and additives such as pigments may be added as necessary. Next, the obtained varnish for impregnation is impregnated and coated on a sheet-shaped substrate and dried at room temperature to 170 ° C. to obtain a prepreg having no tackiness. The setting of the drying temperature at this time depends on the solvent and the initiator used. Stack the required number of prepregs obtained at the end, 100-250 ℃, 1-100kgf / cm ²
A curing reaction is carried out under pressure to obtain a laminate. As the sheet-like substrate, generally, almost all the ones used for the laminated material can be used. For example, for inorganic fibers, SiO ₂ , Al ₂ O ₃
There are various kinds of glass fibers such as E glass, C glass, A glass, T glass, D glass and Q glass, etc. Also,
Organic fibers include aramid fiber, PTFE fiber, polyamide fiber and the like.

〔Example〕

<Example 1.> Poly (p-hydroxybromostyrene) (Maruzen Sekiyu)
Was reacted with 2,3-epoxypropyl chloride and further reacted with methacrylic acid chloride to obtain a copolymer prepolymer having a 2,3-epoxypropanoxy group: methacrynoyloxy group = 5: 5. The obtained prepolymer was dissolved by heating using methyl isobutyl ketone in a solvent at 80 ° C. for 30 minutes to obtain a varnish having a solid content of 40%. Furthermore, as a radical polymerization initiator, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 (NOF Perhexin 25B)
2 parts by weight to 100 parts by weight of the solid content of varnish, and an epoxy equivalent of benzoguanamine (Tokyo Kasei, active hydrogen = 4) was added as a curing agent for the epoxy. The obtained impregnating varnish was impregnated and coated on a glass cloth (E-glass manufactured by Nitto Boseki, thickness 0.05 mm) and dried in constant temperature air at 100 to 120 ° C. for 20 minutes,
A prepreg having no tackiness was obtained. Next, stack 20 prepregs and heat them at a pressure of 30kgf / cm, 130 ° C for 30 minutes, then add 220
The temperature was raised to ℃ and the adhesive curing reaction was carried out in the press for 2 hours to obtain a laminated plate.

<Example 2.> The prepolymer used in Example 1 and epoxy-modified polybutadiene (Nippon Soda) were heated and dissolved at a mixing ratio of 50:50 using methyl isobutyl ketone as a solvent at 80 ° C. for 30 minutes to obtain a solid content of 40%. I got a varnish. A laminated board was obtained in the same manner as in Example 1 below.

<Example 3.> Poly (p-hydroxybromostyrene) (Maruzen Sekiyu)
Is reacted with 4- (1,2-epoxyethyl) phenyl chloride, and the side chain is 4- (1,2-epoxyethyl) phenoxy group: methacrynoyloxy group = A 6: 4 copolymer prepolymer was obtained. A laminate was obtained in the same manner as in Example 1 by using the obtained prepolymer and epoxy-modified polybutadiene (Nippon Soda Co., Ltd.) in a weight mixing ratio of 60:40.

Example 4. Poly- (p-hydroxybromostyrene) (Maruzen Sekiyu) was reacted with 2,3-epoxypropyl chloride,
Further, an etherification reaction is carried out with allyl chloride and the side chain is a 2,3-epoxypropanoxy group: an allyloxy group =
A 7: 3 copolymer prepolymer was obtained. The resulting prepolymer and partially cyclized 1,2-polybutadiene were mixed in a weight ratio of 70:30 to form xylene as a solvent to obtain a varnish having a solid content of 40%. A laminated board was obtained in the same manner as in Example 1 below.

Example 5. Copolymer prepolymer and polybutadiene used in Example 1 and, further, a diacrylate of a reaction product of tetrabromobisphenol A and ethylene oxide for improving fluidity at the time of molding (Daiichi Kogyo Seiyaku Co., Ltd.). The weight compounding ratio 35:50:
In 15, a varnish was prepared in the same manner as in Example 1 to obtain a laminated board.

<Comparative example> Poly (p-hydroxybromostyrene) (Maruzen Sekiyu)
Was subjected to esterification with methacrylic acid chloride alone to prepare a laminated sheet in the same manner as in Example 1 using the prepolymer in which all side chains were methanoyloxy groups and the epoxy-modified polybutadiene used in Example 1.

The characteristics of the laminate thus obtained are shown in the table. Regarding the crack resistance of the laminated board due to thermal shock, both the 288 ° C solder float 1 minute (heat shock test) and the 125 ° C, 20 minutes and -65 ° C, 20 minute heat cycle tests were performed to check for cracks. Examined.

As shown in the table, it was found that by using the polymer cross-linking flame retardant composed of the copolymerized prepolymer having an epoxy ring in the present invention, the crack resistance of the laminated plate due to the thermal shock is significantly improved. It also has excellent heat resistance and electrical characteristics.

In addition, in this polymer cross-linked prepolymer, by introducing an ion-crosslinking type epoxy ring instead of a radical-crosslinking type unsaturated group in all side chains, the curing shrinkage amount at the time of curing is reduced, and further, the ionic reaction Has a slower reaction rate than the radical reaction, and a cured product can be obtained while sufficiently relaxing the residual stress during curing. Therefore, the residual stress of the obtained cured product is very small, and the crack resistance of the laminated plate at the time of thermal shock such as heat shock or heat cycle is significantly improved.

〔The invention's effect〕

According to the present invention, the relative permittivity is 3.5 or less, which is lower than that of the conventional polyimide material (relative permittivity 4.7), and when applied to a multilayer printed board, a significant improvement in signal transmission speed can be expected. In addition, compared with the polybutadiene material currently under development, by using a polymer cross-linked prepolymer as a flame retardant, it exhibits excellent properties in thermal expansion coefficient that is dimensional stability and thermal decomposition start temperature that is a measure of heat resistance.

Front page continued (72) Inventor Masao Suzuki 4026, Kujimachi, Hitachi, Hitachi, Ibaraki 4026 Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Akio Takahashi 4026, Kujicho, Hitachi, Ibaraki Hitachi, Ltd. (72) ) Inventor Toshikazu Narahara 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd. (56) Reference JP-A-62-161846 (JP, A)

Claims (4)

(57) [Claims] 1. The following general formula I (In the formula, R ₁ is a reactive group having an epoxy ring, R ₂ is a reactive group having an unsaturated bond, and m and n are numbers from 1 to 4. Also, X, Y
Is a copolymerization ratio, both in the range of 0.3 to 0.7, and X +
Y = 1 is satisfied. ) A flame-retardant resin composition comprising a prepolymer represented by the formula (1) as an essential component. 2. A reactive unsaturated group R _{2 in the} prepolymer.
Is allyloxy, vinyloxy, isobutenyloxy,
The flame-retardant resin composition according to claim 1, wherein the flame-retardant resin composition is acrynoyloxy, methacrynoyloxy, epoxyacrynoyloxy, or epoxymethacrynoyloxy. 3. The prepolymer and an unsaturated group-containing side chain 1,
The flame-retardant resin composition according to claim 1, which comprises a 2-polybutadiene derivative as an essential component. 4. A laminated material in which a synthetic resin is impregnated in a base material and dried prepregs are laminated and adhered to each other, wherein the synthetic resin is represented by the following general formula I: (In the formula, R ₁ is a reactive group having an epoxy ring, R ₂ is a reactive group having an unsaturated bond, and m and n are numbers from 1 to 4.
X and Y are copolymerization ratios, both in the range of 0.3 to 0.7, and X + Y
= 1 is satisfied. ) A flame-retardant resin composition containing a prepolymer represented by the formula (1) as an essential component.