JP2002097242A - High heat resistant flame retardant curing agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition which attains halogen free flame retardancy, corresponding to a lead-free solder with a high melting temperature and to provide high heat resistant environmental harmony type materials using the same. SOLUTION: A phenol resin having a structure of phosphoric ester shown by the formula (I) and a composition using the same are provided. (In the formula, R1 or R2 shows either the same or different a hydrogen atom, a lower alkyl group, an aryl group or an aralkyl group, x shows an integer of 0-3, y shows an integer of 0-5, n or m shows the same or different natural number).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curing agent which makes an epoxy resin composition flame-retardant without using a halogen compound, and relates to a prepreg and a laminate using the same.

[0002]

2. Description of the Related Art A thermosetting resin represented by an epoxy resin is most often used for a printed wiring board widely used in electric and electronic equipment. A halogen-containing compound is generally used as a resin composition in consideration of flame retardancy in order to ensure fire safety.
A typical example of the halogen compound is an aromatic bromide such as a brominated epoxy resin, which is excellent in that it can impart flame retardancy without deteriorating other physical properties. However, these compounds not only emit toxic hydrogen bromide during combustion, but also can generate toxic polybromobenzodioxane and polybromobenzofuran, known as endocrine disruptors (environmental hormones), during incomplete combustion. There is. In response to these indications, the development of an environmentally friendly flame retardant in place of a bromine-containing flame retardant is being studied.

As non-halogen flame retardants, nitrogen compounds, phosphorus compounds, metal hydroxides and the like are known.
Nitrogen compounds have low efficacy and are therefore difficult to be flame retarded when used alone, and must be combined with other flame retardants. Since it is necessary to add a large amount of metal hydroxide, a change in physical properties such as the dielectric constant of the laminate has been a serious problem. Various studies have been made on phosphorus compounds because they can be made flame retardant with a relatively small amount. However, triphenyl phosphate and cresyl diphenyl phosphate, which are common phosphorus-based flame retardants, not only significantly lower the glass transition point of the resin due to the plastic action of these compounds, but also cause the plating during processing of laminated boards. In the process, there is also a problem that the phosphorus compound is eluted and contaminated in the treatment solution. As a solution to the problem of such an addition type phosphorus compound, there is a method using an epoxy compound containing phosphorus.
395, JP-A-61-148219, JP-A-62-223215, JP-A-5-393
45 and the like. However, compounds in which an aliphatic group is bonded to a phosphorus atom (JP-A-61-148219, JP-A-62-223215)
Has a problem in heat resistance. On the other hand, compounds in which an aromatic atom is bonded to a phosphorus atom (JP-A-61-134395, JP-A-5-39345)
However, they have high heat resistance but are expensive due to special raw materials, and have a problem that synthesis and purification are not easy.

In recent years, in order to solve these problems, use of a phosphorus compound which reacts with an epoxy resin and is immobilized has been studied. For example, in JP-A-11-124489, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is used, but this compound reacts not only with epoxy resin but also with ketones and quinones. There are limitations on the additives and solvents that can be used, and further improvements have been desired. In addition, use of solder that does not use lead, which is a harmful metal, is being studied as a similar consideration to the environment.
Various alloy compositions are being studied for the lead-free solder, but it is said that when importance is placed on connection reliability, a composition having a higher melting temperature than the current lead solder is required. For this reason, a printed wiring board, such as a semiconductor package, for which connection reliability is required, is required to have higher heat resistance than ever.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been conceived to solve such a problem, and an object of the present invention is to provide a resin composition which exhibits high flame retardancy without using a halogen compound. It is the purpose. That is, the present invention provides an environment-friendly resin composition which has good operability such as no solvent limitation at the time of preparing a prepreg, has a high glass transition point as a laminate obtained, and can cope with a high melting temperature of lead-free solder. That is.

[0006]

Means for Solving the Problems The present inventors have intensively studied a curing agent to be combined with an epoxy resin and a mechanism of developing flame retardancy. As a result, by incorporating a phosphate ester structure having a flame-retardant effect into the molecule of the curing agent, a decrease in heat resistance due to a plasticizer effect seen in the addition type phosphate ester is prevented and further incorporated. By adopting a novolak type as the skeleton of the base resin, a high crosslink density was maintained and high heat resistance was realized. The inventors have found that the above object is satisfied by using the phenol resin type curing agent having the phosphate ester structure, and have completed the present invention. That is, the present invention is as follows. (1) The following general formula (1)

Embedded image (Wherein R ¹ and R ² are the same or different hydrogen atoms, lower alkyl groups, aryl groups or aralkyl groups, x is an integer of 0-3, y is an integer of 0-5, n
And m represent the same or different natural numbers). (2) A flame-retardant epoxy resin composition comprising an epoxy resin and another curing agent, characterized by containing a phosphorus-containing phenolic resin represented by the general formula (1) as an essential component. (3) A prepreg characterized by impregnating a base material with the resin composition of the above (2), and a flame-retardant laminate obtained by laminating one or more prepregs and curing by heating and pressing. It is a board.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The phosphorus compound of the present invention represented by the above general formula (1) is obtained by reacting a phenol resin with a diaryl phosphorohalide in the presence of a base to partially diallyl phosphorylate. Can be easily synthesized. An example in which an unsubstituted phenol resin (generally called a phenol novolak resin, hereinafter abbreviated as “PNV”) and diphenyl phosphorochloridate (hereinafter abbreviated as “DPC”) is used.

Embedded image (In the formula, n and m have the same meaning as described above.) For the reaction, a general method known as a method for producing a triaryl phosphate ester can be used. For example, the method can be carried out by a method in which DPC is dropped into an organic solvent containing PNV and a base, but is not limited thereto. The base as a scavenger for hydrogen chloride by-produced in the reaction is not particularly limited as long as it is a tertiary amine, and triethylamine, pyridine and the like can be used. Among them, triethylamine is preferred. The organic solvent used is not particularly limited,
Ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, aprotic polar solvents such as N, N-dimethylformamide, and ethers such as tetrahydrofuran are preferred. Further, two or more kinds of solvents can be used as a mixture. The reaction temperature is appropriately selected depending on the solvent.
60 ° C. is preferred.

The phosphorus-containing phenolic resin of the present invention represented by the above general formula (1) obtained by this reaction is treated with D
It may be abbreviated as PC-PNV. The phosphorus-containing phenolic resin of the present invention represented by the above general formula (1) (DPC-PNV)
Is the ratio of PNV to DPC in n / n
It is determined by (m + n). When n / (m + n) is small, the flame retardant action is reduced due to the small phosphorus content. Therefore, to increase the content in the composition to maintain flame retardancy,
It must be used in combination with other flame retardants. On the other hand, when n / (m + n) is large, the phosphorus content increases, but the phenolic hydroxyl group that reacts with the epoxy resin decreases, so that the crosslinking density at the time of curing decreases, and heat resistance may decrease. . From the above viewpoints, n / (m + n) needs to be 0.05 or more, and is usually 0.1.
It is preferably from 1 to 0.95, more preferably from 0.2 to 0.8. In addition, when the phenol resin (PNV) as a raw material has a small molecular weight, increasing the DPC conversion rate (n / (m + n)) may include a compound in which all of the hydroxyl groups are converted to DPC and cannot react with the epoxy resin. There is. On the other hand, if the molecular weight is large,
An increase in the viscosity of the resin varnish may deteriorate the impregnating property on the substrate. From the above viewpoints, it is preferable that the PNV has a low content of low molecular binuclear substance and a molecular weight of 10,000 or less.

The resin composition of the present invention contains an epoxy resin and the above-mentioned phosphorus-containing phenol resin as essential components. The epoxy resin is not particularly limited as long as it is an epoxy resin that is not halogenated. Specific examples thereof include glycidyl ethers of bisphenol A and bisphenol F, and glycidyl ethers of phenol novolak and cresol novolak.
Among them, glycidyl ether of phenol novolak is preferred. The amount of the above-mentioned phosphorus-containing phenol resin, which is a curing agent and a flame retardant, is appropriately selected according to the phosphorus content related to the development of flame retardancy, but is usually 0.1% as the phosphorus content in the resin composition. To 5% is preferred. The amount ratio of the epoxy resin and the curing agent is adjusted by the equivalent ratio, but only with the phosphorus-containing phenol resin as the curing agent,
In some cases, the equivalence ratio cannot be adjusted. In such a case, another curing agent having no flame retardant function can be used in combination. The curing agent is not particularly limited, and a known curing agent can be used. Specific examples include phenol resins such as phenol novolak and cresol novolak, acid anhydrides such as trimellitic anhydride, amines such as diethylenetriamine, imidazoles such as 2-methylimidazole, dicyandiamide and derivatives thereof.

It should be noted that other thermosetting resins can be used in combination with the resin composition of the present invention as long as the purpose is not impaired. Specific examples include a cyanate resin represented by bisphenol A dicyanate or a prepolymer thereof, bismaleimides, a resin obtained by modifying a cyanate resin with bismaleimide, and a polymerizable resin such as (meth) acrylate or diallyl terephthalate. Examples include, but are not limited to, saturated group-containing resins. Also, a thermoplastic resin can be added. Specifically, polyphenylene ether, polystyrene, polybutadiene,
Examples include, but are not limited to, polyimide and various modified resins of these resins. Incidentally, an inorganic or organic filler can be added to the composition of the present invention according to the purpose. Specific examples of the inorganic filler include, but are not limited to, aluminum hydroxide, silica, alumina, aluminum nitride, silicon nitride, silicon carbide, mica, talc, and the like and their surface-treated products.

The production of a copper-clad laminate using the resin composition of the present invention is performed according to a known method. That is, a resin varnish prepared by dissolving a thermosetting resin composition containing a phosphorus-containing phenol resin or the like in an organic solvent is prepared, and the resin varnish is impregnated into a base material, and heat-treated to form a prepreg. This is a method of laminating and heat forming to obtain a copper-clad laminate. As the solvent used for the resin varnish,
A single solvent or a mixture of two or more solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, N, N-dimethylformamide and the like. Examples of the substrate to be impregnated with the resin varnish include a woven fabric, a nonwoven fabric, a mat, a paper made of an inorganic or organic fiber such as a glass fiber, an alumina fiber, a polyester fiber, and a polyamide fiber, or a combination thereof. The heat treatment conditions for obtaining the prepreg are appropriately selected depending on the solvent used, the amount of the catalyst and the type of other additives, but can be performed under generally known conditions. For example, 100
A method of heating at a temperature of from 0 to 200 ° C for from 1 to 30 minutes is exemplified. The heat forming conditions for laminating the prepreg and the copper foil to form a copper-clad laminate are as follows: a temperature range of 150 ° C. to 250 ° C.
A method of hot pressing at a molding pressure of 1 MPa to 10 MPa for 30 minutes to 300 minutes is exemplified.

[0012]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these examples. In the examples and comparative examples, parts and percentages are by weight unless otherwise specified. Synthesis Example 1 [Synthesis of DPC-PNV] Phenol novolak resin (PNV) [TD-2093, manufactured by Dainippon Ink and Chemicals, Inc.]
(Number-average molecular weight Mn = 1,400)] and charged into a 5 liter reactor equipped with a thermometer, a stirrer, a cooling pipe, and a dropping pipe. After cooling this solution to 5 ° C., diphenyl phosphorochloridate (DPC) [Daichi Chemical Co., Ltd.
DPC] and 500 ml of methyl ethyl ketone. Next, while maintaining the reaction temperature at 5 ° C., 106 g of triethylamine was added dropwise to carry out the reaction. After the completion of the dropwise addition, an aging reaction was performed at 25 ° C. for 2 hours to complete the reaction. The reaction solution was washed twice with 500 ml of 0.1N hydrochloric acid and once with 500 ml of water to remove excess triethylamine and triethylamine hydrochloride formed by the reaction. From the washed reaction solution, methyl ethyl ketone was distilled off under reduced pressure to obtain 419 g of the desired DPC-PNV (yield = 99.5).
%). In addition, in the compound of Synthesis Example 1, 1/2 of the hydroxyl group of PNV is converted to DPC, which is called 1 / 2DPC-PNV. For 1 / 2DPC-PNV, it was confirmed by gel permeation chromatography (GPC) that DPC and PNV were bound by the absence of low molecular substances, and the absorption of phosphate ester was confirmed by infrared absorption spectrum (IR) analysis. (P = O: 1200Cm-1, POC: 980cm-1).

Synthesis Example 2 A PNV of 200 g and DPC 128 were prepared in the same manner as in Synthesis Example 1.
g, 53 g of triethylamine and 1/4 DPC-PNV
310 g (yield = 99.8%) were obtained.

Synthesis Example 3 [Synthesis of Raw Material Phenol Resin] 470 parts of phenol, bisphenol A 1140
Part, 738 parts of formalin (HCHO 35%) and oxalic acid
16 parts were charged into a reactor, and a reaction was carried out under heating and refluxing for 60 minutes. Next, 8 parts of hydrochloric acid was added and the reaction was continued for another 40 minutes.

After completion of the reaction, the reaction solution was poured into 2 liters of ice water to stop the reaction and solidify the product. The precipitated crude product was collected by suction filtration and washed three times with water. The crude product after washing is transferred to a flask,
Heating to 50 ° C. distilled off water and low boiling impurities.
Finally, the product remaining in the flask was poured into an aluminum vat and solidified. The yield of the product obtained is 17
Gg analysis showed that the number average molecular weight was Mn = 95.
It was a polymer of 1. In addition, as a result of measuring a hydroxyl equivalent by a titration method, it was 114 (g / mol), and it was confirmed that it was a target. The product obtained is a mixed novolak in which phenol and bisphenol A are in a 1: 1 molar ratio, hereinafter abbreviated as "KNV".

Synthesis Example 4 In the same operation as in Synthesis Example 1, Synthesis Example 3 was used instead of PNV.
Novolak resin (KNV) 200g, DPC 236g, triethylamine
Using 98 g, 401 g of 1 / 2DPC-KNV (yield = 99.4
%).

Example 1 100 parts of phenol novolak epoxy (trade name: Epicron N-770, manufactured by Dainippon Ink and Chemicals, Inc.), and the DPC-modified phenol novolak resin (1/1 / 38 parts of 2DPC-PNV) and 41 parts of a phenol novolak resin (TD-2093 manufactured by Dainippon Ink and Chemicals, Inc.) as a curing agent for adjustment were added to methyl ethyl ketone.
Dissolved in 179 parts to make a solution having a nonvolatile content of 50%, and 0.1 part of a curing catalyst 2-ethyl-4-methylimidazole (trade name: Cureazole [2E4MZ] manufactured by Shikoku Chemicals Co., Ltd.) was added, and a resin varnish was added. It was adjusted. This resin varnish is 0.1m thick
m glass cloth (1031 manufactured by Arisawa Seisakusho)
A prepreg having a resin amount of 50% was obtained by heating and aging at 50 ° C. for 5 minutes. Four prepregs are laminated, and copper foil (3EC-III manufactured by Mitsui Kinzoku Kogyo KK) with a thickness of 18 μm is laminated on both sides, the surface pressure is 2 MPa, and the temperature is raised to 1.5 ° C./m.
The vacuum heating press was performed at 200 ° C. for 120 minutes at “in” to obtain a copper-clad laminate. Table 1 shows the characteristics of the laminate.

Examples 2 and 3 and Comparative Examples 1 to 4 A prepreg similar to that of Example 1 was prepared using the resin composition shown in Table 1, and a copper-clad laminate was similarly obtained. Table 1 shows the characteristics of the laminate. In Comparative Example 1, resorcinol bisdiphenyl phosphate (RDP) that does not undergo a curing reaction
Is high, the glass transition point is lowered, and the heat resistance is poor.
In Comparative Example 2, by using aluminum hydroxide in combination, R
Although the amount of DP used was reduced, the solder heat resistance was low due to the effect of decomposition of aluminum hydroxide. In Comparative Example 3, the heat resistance and the electrical characteristics were good because no flame retardant component was added, but the flame was burned to the uppermost end without extinguishing in the flame retardancy test. Comparative Example 4 is an example in which a brominated epoxy was used as a flame retardant component.

[0019]

[Table 1] (a) Phenol novolak epoxy manufactured by Dainippon Ink and Chemicals, Inc. (b) Phenol novolak manufactured by Dainippon Ink and Chemicals, Inc. (c) Phosphorus-containing phenolic resin of Synthesis Example 1 (d) Phosphorus-containing phenolic resin of Synthesis Example 2 Phenol resin (e) Phosphorus-containing phenol resin of Synthesis Example 4 (f) Resorcinol bisdiphenyl phosphate manufactured by Ajinomoto Fine Techno Co., Ltd. (g) Aluminum hydroxide manufactured by Showa Denko KK (h) Nippon Kayaku Co., Ltd. Tetrabromobisphenol A (i) Curing catalyst: 2-Ethyl-4-methylimidazole manufactured by Shikoku Chemicals Co., Ltd. In Table 1, physical properties were measured using the methods or measuring instruments described below. (1) Flame retardancy: Evaluated by burning time according to the UL94 vertical method. Specimens were obtained by cutting out a copper foil of various copper-clad laminates by etching and removing 12.7 mm in width and 127 mm in length. In the test, two flames were applied to each of the five test pieces, and the extinction time was measured. UL94V-0 has an average extinction time of less than 5 seconds and a maximum extinction time of less than 10 seconds. Those that do not extinguish become HB. (2) Glass transition temperature (Tg): Dynamic viscoelasticity measurement (DMA) was performed at a heating rate of 5 ° C./min at a frequency of 10 Hz using SSC5200 manufactured by Seiko Instruments Inc. (Tan δ) It was determined from the peak. (3) Copper foil peel strength: JIS standard (C6481)
Performed in accordance with Copper foil is available from Mitsui Kinzoku Kogyo Co., Ltd.
EC-III (18 μm) was used. The unit is kN / m. (4) Solder Resistance at 280 ° C. Ten laminated plates of 5 cm square were prepared and immersed in a 280 ° C. solder bath for 10 minutes. The surface condition of the laminated plate after immersion was visually observed to determine whether there was any abnormality such as blistering. The notation of the result is the number of test pieces in which no abnormality has occurred (10/10 when all are normal).

[0020]

The phenolic resin having a phosphate ester structure in the molecule thereof and the composition using the same according to the present invention are non-halogen and have excellent heat resistance. Therefore, it is useful as an environment-friendly material that can handle lead-free solder having a high melting temperature, which requires connection reliability, and can realize flame retardancy without using a halogen compound.
Particularly, it is useful for a substrate for a semiconductor package or the like in which high melting point solder is used from the viewpoint of connection reliability.

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Seio Hiramatsu 6-1-1 Shinjuku, Katsushika-ku, Tokyo Mitsubishi Gas Chemical Co., Ltd. Tokyo Research Laboratory F-term (reference) 4F072 AA07 AB05 AB06 AB09 AB11 AD18 AL09 4F100 AB17B AK33A AK33K AK53A AT00B BA02 BA10A BA10B DH01A GB43 JJ07A 4J033 CA02 CA11 CA19 CA28 CA29 CA44 CB18 CC03 CC09 CD04 HA07 HA12 HA28 HB01 4J036 AA01 AD08 AF06 DB06 FB08 HA11 JA08 KA01

Claims (5)

[Claims] 1. A phosphorus-containing phenolic resin obtained by partially diarylphosphorizing a hydroxyl group of a phenolic resin in which a phenol type compound is bound by a methylene group. 2. A compound represented by the following general formula 1. (Wherein R ¹ and R ² are the same or different hydrogen atoms, lower alkyl groups, aryl groups or aralkyl groups, x is an integer of 0-3, y is an integer of 0-5, n
And m represents the same or different natural numbers). 3. A phosphorus-containing phenol resin according to claim 1, wherein the R ¹ and R ² of the general formula 1 of claim 2 are all hydrogen atoms. 4. The phosphorous-containing composition according to claim 1, wherein
A flame-retardant resin composition containing a phenol resin as an essential component. 5. A laminate obtained by heating and curing the resin composition according to claim 4.