JP2531387B2 - Novolac phenolic resin - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novolac type phenolic resin which is a raw material for a heat resistant epoxy resin.

[0002]

2. Description of the Related Art At present, heat-resistant epoxy resins which are widely available on the market include glycidyl ether of phenol novolac and glycidyl ether of O-cresol novolac. These epoxy resins are used in fields where heat resistance is particularly required, for example, sealing materials for semiconductor integrated circuits, laminated boards for printed wiring boards and the like.

[0003]

However, the required physical properties of the heat-resistant epoxy resin are becoming severer year by year, and higher heat resistance is required. At the same time, it is usually required to have flexibility which is a physical property contrary to heat resistance.

For sealing of semiconductor integrated circuits, for example, a material that relieves internal stress and is excellent in crack resistance is required. This internal stress is represented by the product of the linear expansion coefficient and the elastic modulus, and a material having a low linear expansion coefficient and a low elastic modulus is desired. Further, in the case of a laminated board such as a printed wiring board, improvement in drill workability is required, and a material having a low elastic modulus is desired.

The present invention provides a well-balanced raw material for epoxy resins having a high glass transition temperature and a low elastic modulus.

The present invention provides a compound of formula (I)

[0006]

Embedded image (In the formula, R ¹ , R ² and R ³ are each selected from the group consisting of hydrogen atom, hydrocarbon group and halogen atom, and n is a number of 20 to 50). A phenolic resin is provided.

Specific examples of the substituents R ¹ , R ² and R ³ include a hydrogen atom, a methyl group, a butyl group, a phenyl group, a chlorine atom and a bromine atom, preferably a hydrogen atom,
It is a bromine atom. The number of repeating units n is 2 or more and 50 or less. When n exceeds 50, a large amount of a high molecular weight product is produced, and the glycidyl ether has a high viscosity even under high temperature conditions, which makes handling difficult. Further, when n is less than 2, the glycidyl ether becomes a semi-solid or viscous liquid at room temperature and becomes difficult to handle. The novolac type phenolic resin of the present invention has the formula

[0008]

Embedded image (In the formula, R ¹ , R ² and R ³ are the same as those in the formula (I).) The p-isopropenylphenols are obtained by polymerizing in the presence of an alkali catalyst.

As a method for synthesizing this p-isopropenylphenol, as shown in Japanese Patent Publication No. 38-1368, a method by thermal decomposition of bisphenol represented by bisphenol A, or dehydrogenation of p-isopropylphenol. Is known. In both of these methods, the product contains phenol or saturated alkyl group-substituted phenols as impurities. The p-isopropenylphenols thus synthesized are polymerized in the presence of an alkali catalyst to obtain a compound of formula (II).

[0010]

Embedded image (In the formula, R ¹ , R ² , and R ³ each represent a hydrogen atom, a hydrocarbon group, and a halogen atom, and n represents a number of 2 to 50), and a novolac type phenol resin represented by the formula is mainly obtained. It should be noted that the impurities described above do not cause much trouble during this polymerization reaction. The alkali catalyst used in this polymerization reaction is preferably an alkali metal or alkaline earth metal hydroxide, more preferably sodium hydroxide, potassium hydroxide or the like. The amount of the alkali catalyst used is about 0.001 mol to 0.1 mol with respect to 1 mol of p-isopropenylphenols.

The polymerization temperature is 140 ° C to 250 ° C.
Below 140 ° C, it is difficult to obtain a sufficient degree of polymerization,
At 0 ° C or higher, decomposition of the polymer is likely to occur, which is not preferable. This polymerization reaction can be carried out under atmospheric pressure, but can also be carried out under reduced pressure by removing the above-mentioned impurities existing in the system out of the system.

The novolac type phenolic resin of the present invention is
Although it can be used as a curing agent for epoxy resins, it is mainly used as an epoxy resin by converting it into glycidyl ether which is another invention. In other words, another invention is the formula (II
I)

[0013]

[Chemical 6] (In the formula, R ¹ , R ² and R ³ each represent a hydrogen atom, a hydrocarbon group or a halogen atom, and n represents a number of 2 to 50). It is a glycidyl ether of phenolic resin. This is obtained by glycidyl etherification of the novolak type phenol resin represented by the general formula (I).

When the novolac type phenolic resin represented by the general formula (II) is glycidyl etherified, the formula (IV)

[0015]

[Chemical 7] (In the formula, R ¹ , R ² and R ³ each represent a hydrogen atom, a hydrocarbon group or a halogen atom, and n represents a number of 2 to 50). It becomes glycidyl ether of phenol resin.

To convert a novolak type phenolic resin into a glycidyl ether, for example, as shown in JP-A-58-189223, a glycidyl ether is produced from a monohydric or polyhydric phenol by reaction with epichlorohydrin. A commonly used method can be applied.

The composition containing the thus obtained glycidyl ether as a main component and a curing agent mixed therein can be suitably used as a raw material for electric and electronic materials. Currently, semiconductor encapsulation materials that are becoming higher in density and larger in size are required to have good heat resistance, that is, high glass transition temperature and low stress, that is, low elastic modulus, which are incompatible with each other. The encapsulating material containing glycidyl ether of the novolac type phenolic resin represented by the formula (III) or the formula (IV) as a main component can meet this demand.

In addition to the glycidyl ether, the encapsulant may be a curing agent such as phenol novolac, m-cresol novolac, resorcin novolac, and other novolac type phenols, vinylphenol polymers, isopropenylphenol polymers, and other vinylphenols. ,
Aliphatic amines such as triethylenetriamine, triethylenetetramine, tetraethylenepentamine, dimethylaminopropylamine, diethylaminopropylamine and aminoethylethanolamine, alicyclic amines such as menthanediamine and n-aminoethylpiperazine,
Metaphenylenediamine, diaminodiphenylmethane,
Aromatic amines such as diaminodiphenyl sulfone, metaxylenediamine, metaaminobenzylaminebenzidine, 4-chloro-o-phenylenediamine, bis (3,4-diaminophenyl) sulfone, 2,6-diaminopyridine, polyamide resin, Acid anhydrides such as pyromellitic dianhydride, succinic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, maleic anhydride, methylnadic acid anhydride, glutaric anhydride, and tetrabromophthalic anhydride, but among them phenol Novolak type phenols such as novolac and m-cresol novolac, vinylphenols such as vinylphenol polymer and isopropenylphenol polymer are preferable.

Further, inorganic fillers such as silica, alumina, talc, clay and glass fibers, imidazoles,
A curing accelerator such as a tertiary amine and an internal release agent such as stearic acid, calcium stearate, carnauba wax and montan wax are usually added.

The encapsulant is generally used when encapsulating a semiconductor integrated circuit by transfer molding. The composition ratio of the encapsulant changes depending on each type,
As a general rule, the amount of the curing agent is such that the number of moles of the functional groups of the curing agent is the same as the number of moles of the epoxy groups of the glycidyl ether, and the amount of the filler is almost the closest to the volume of the total amount of the mixture. The curing accelerator is used in a small amount such as a catalytic amount, and the internal release agent is used in an amount of about 0.2 to 2.0% by weight based on the total blending amount.

[0021]

EXAMPLES The present invention will be described below with reference to examples. In the examples, the softening point is measured by JIS-K2531 (petroleum asphalt softening point test method (ring and ball method)). The epoxy equivalent is defined as gram equivalent per mol of glycidyl ether group. The glass transition temperature and elastic modulus were measured with Rheolograph Solid (manufactured by Toyo Seiki Co., Ltd.). The structure of a polymer is analyzed by ¹³ C-NMR spectroscopy (FT-NMR, Hitachi, Ltd.) using deuterium-substituted chloroform as a solvent.
-90H).

Example 1 (1) Production of novolac-type phenolic resin A mixture obtained by thermal decomposition of bisphenol A (48% by weight of p-isopropenylphenol, phenol) according to the description of Example 1 in Japanese Examined Patent Publication No. 38-1368. 42 wt%, p
-Isopropenylphenol oligomer 10 wt%) 3
2.69 g of 48% NaOH aqueous solution was added to 00 g, and at 180 ° C. under reduced pressure (50 Torr) while distilling phenol.
Heat up to. Furthermore, the temperature is kept at 180 ° C. for 4 hours to complete the polymerization. After completion of the polymerization, the reaction product was put into a large amount of dilute aqueous HCl solution to precipitate the polymer product, thereby obtaining a yellowish brown resin. The softening point of this resin was 105 ° C. Of this resin
^{The 13} C-NMR chart is shown in FIG. 1. ¹³ C-NM in Fig. 1
The attributions of the peaks in the R chart are as follows.

[0023]

Embedded image 29-33ppm 41-43ppm Aromatic ring carbon 114-156ppm

(2) Synthesis of glycidyl ether of novolak type phenolic resin Novolak type phenolic resin obtained in (1) of Example 1 in a 1 liter flask equipped with a thermometer, a separating tube, a dropping funnel and a stirrer. 0 mol (as phenolic hydrogen groups) is dissolved in 7.0 mol epichlorohydrin. Temperature 8
While maintaining at 0 ° C. and a pressure of 250 mmHg, 48% NaOH aqueous solution was continuously added in 6 hours. During this time, epichlorohydrin and water were azeotropically liquefied to be liquefied and separated into an organic layer and an aqueous layer by a separation tube, the aqueous layer was removed outside the system, and the organic layer was circulated inside the system. After completion of the reaction, the temperature was kept for 1 hour to evaporate and remove unreacted epichlorohydrin, and the reaction product was dissolved in methyl isobutyl ketone. Next, after filtering off the by-product salt, methyl isobutyl ketone was evaporated and removed to obtain a solid resin at room temperature. This resin had a softening point of 68 ° C. and an epoxy equivalent of 208. The ¹³ C-NMR chart of this resin is shown in FIG. ¹³ C in FIG.
-Assignment of peaks in the NMR chart is as follows.

[0025]

[Chemical 9] 29-32ppm 41-43ppm
44.8ppm 50.2ppm 68.8ppm Aromatic ring carbon 112-157ppm

Example 2 Polymerization conditions were heated to 200 ° C. in the same manner as in Example 1 (1), and the temperature was kept at 200 ° C. for 2 hours. The softening point of the obtained resin was 133 ° C. Further, this resin was glycidyl etherified in the same manner as in Example 1 (2) to obtain a solid resin at room temperature. This resin had a softening point of 82 ° C. and an epoxy equivalent of 211.

Example 3 p-Isopropylphenol was passed through a reaction layer at 600 ° C. filled with a MnO ₂ -based catalyst to dehydrogenate the resulting mixture (27% by weight of p-isopropenylphenol and 65% by weight of p-isopropenylphenol). , P-isopropenylphenol oligomer 6 wt%, cresols 1.5 wt%,
A yellowish brown resin was obtained in the same manner as in Example 1 (1) using 300 g of an unknown product (0.5 wt%). The softening point of this resin is 9
It was 9 ° C. Further, this resin was polymerized in the same manner as in (2) of Example 1 to obtain a solid resin at room temperature. This resin had a softening point of 62 ° C. and an epoxy equivalent of 208.

Reference Example 1 1.0 mol of the glycidyl ether of the novolak-type phenol resin obtained in Example 1 (2) (as an epoxy group, specifically 208 g) and 1.0 mol of phenol novolak (phenolic hydroxyl group) As a curing accelerator, 0.8 part by weight of tris (dimethylaminomethyl) phenol (trade name: Sumicure D, manufactured by Sumitomo Chemical Co., Ltd.) with respect to the total amount was roll-kneaded to obtain a composition. Next, this composition was molded into a 1 mm sheet by pressing and heating. This molded product was post-cured at 170 ° C. for 5 hours to prepare a cured molded product. The glass transition temperature of this molded product was 236 ° C. The elastic modulus at 25 ° C. was 2.18 × 10 ⁹ N / m.

Reference Example 2 A cured molded article was obtained in the same manner as in Reference Example 1, except that the glycidyl ether of the novolak type phenolic resin obtained in Example 2 was used. The glass transition temperature of this molded product is 25.
The elastic moduli at 4 ° C. and 25 ° C. were 2.22 × 10 ⁹ N / m.

Comparative Example 1 Glycidyl ether of commercially available cresol novolac, which is currently mainly used as an epoxy resin for semiconductor encapsulation (Sumiepoxy ES manufactured by Sumitomo Chemical Co., Ltd., trade name)
A cured molded article was prepared by using CN-220, a softening point of 67 ° C., an epoxy equivalent of 207) as a main component, and a formulation similar to that of Reference Example 1. The glass transition temperature of this molded article was 198 ° C., and 2
The elastic modulus at 5 ° C. was 2.72 × 10 ⁹ N / m.

Comparative Example 2 Similar to Comparative Example 1, a reference example using a commercially available glycidyl ether of cresol novolac (manufactured by Sumitomo Chemical Co., Ltd., trade name Sumiepoxy ESCN-220, softening point 80 ° C., epoxy equivalent 206) as a main agent. A cured molded article was made with the same formulation as in 1. The glass transition temperature of this molded article is 219.
A ° C., the elastic modulus at 25 ° C. was 2.81 × 10 ⁹ N / m.

[0032]

EFFECTS OF THE INVENTION The glycidyl ether of the novolac type phenolic resin of the present invention has a glass transition temperature when formed into a cured molded article, as compared with the glycidyl ether of cresol novolac which is generally marketed as a heat-resistant epoxy resin. Is high and the elastic modulus is low. Originally, if the glass transition temperature is raised, the elastic modulus also rises,
Epoxy resin from the glycidyl ether of the present invention,
This point is very well balanced. The encapsulant for electronic parts is required to have a low elastic modulus and heat resistance in order to reduce internal stress due to encapsulation. However, the encapsulant from the glycidyl ether of the present invention satisfies these requirements. Is very suitable for.

[Brief description of drawings]

1 is a ¹³ C NMR chart of the novolac type phenolic resin obtained in (1) of Example 1. FIG.

FIG. 2 is a ¹³ C NMR chart of the glycidyl ether of the novolac type phenolic resin obtained in (2) of Example 1.

Claims (2)

(57) [Claims] 1. Formula (I): (In the formula, R ¹ , R ² and R ³ each represent a hydrogen atom, a hydrocarbon group or a halogen atom, and n represents a number of 2 to 50). Phenolic resin. 2. Formula (II): (In the formula, R ¹ , R ² and R ³ are each selected from the group consisting of a hydrogen atom, a hydrocarbon group and a halogen atom, and n is a number of 2 to 50). The novolak type phenolic resin described in 1.