CA1114090A - Phenol resins and products containing same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A new resol-type phenol resin is described which is obtained by heat-reacting isopropenylphenol or an oligmer thereof or mixtures thereof as partial or whole phenol component of the resin with an aldehyde in the presence of a basic catalyst. Varnishes are obtained by adding a suitable vehicle to the resin. Laminates manufactured by impregnating a base with the phenol resin and heating the impregnated base to cure the resin are obtained with superior mechanical and electrical characteristics.

Description

11~4~90 me pres~nt invention relates to new phenol resins containing isopropènylphenol dimers and an aldehyde.
The invention further relates to varnishes containing the new resin and to laminates having superior mechanical and electrical properties and impregnated with the new resins.
Present-day laminates are manufactured by impregnating a base such as paper or the like with a phenol resin prepared by reacting such substances as phenols, cresols or alkylphenols with formaldehyde and curing the resin. These laminates are widely used as decorative panels or as heat-resisting or electrically insulating materials. In recent years, laminates possessing high mechanical and electrical properties are in particular demand because of the vastly emerging development in telecommuni-cations and electronic instruments. Especially, the commonly used coppér-clad laminates are required not only to possess a high degree of electrically insulating ability I but also to be satisfactory in many other properties such as punching quality, surface resistivity, volume resistivity, soldering heat resistance, dimensional stability, dielectric oonstant, dielectric tangent, and water-absorption. For example, a ; phenol resin containing as the phenol component thereof an alkylphenol such as cresol, propylphenol, butylphenol, octylphenol or nonylphenol is widely used for improving punching quality. A drying oil such as linseed oil, tung oil or cashewnut oil is used as a plasticizer in this case.
Nowever, the use of such plasticizer for improving punching quality has a demerit in that other useful and/or necessary physical properties of the resin are thereby worsened, such as for example insulation resistance, especially insulation resistance after boiling.
In accordance with the present invention, there ~ ~ ' ' :' ,, . . ~...................... .
~ . . ~ ... . , : .

-- 1114~90 is provided a resol-type phenol resin for laminates and the like comprising the product of a basic-catalyst-catalyzed reaction of a dimer of isopropylphenol of the formula selected from 3 C 2 C = CH2 O OH
and Cl3 CH3 C CH = C CH3 OH O
as an essential phenol component with an aldehyde.
The dimer constitutes about 2 to about 60 weight %
based on the total weight of phenol components of the resin.
These new resol resins are particularly useful in the formation of laminates which have improved electrical and mechanical characteristics. The resol resins may be foxmulated with solvents to provide varnishes.
In the general formulas noted above, each hydroxyl group may be present in any of-the ortho-, meta-and para-positions of the benzene ring.
~ he following known methods are typical ones for preparing isopropenylphenol and oligomers thereof including the dimer essentially used in this invention:
(1) In a first method, diphenylolpropane is .
decomposed in the presence of an acidic or alkaline catalyst and p-isopropenylphenol and an oligomer thereof are obtained. From the resultant p-isopropenylphenol, the dimer used in this invention, and indeed the trimer or . ~ ~ .. .. .
.. ... ~ . . . . .. :. .. .

4(~0 mixture of oligomers may be prepared. A p, p'-substituted compound, c~lled Bisphenol A, is generally used as the starting material, but the equivalent p, o'-substituted -compound can also be used. In either case, p-isopropenyl-phenol and an oligomer thereof are obtained as product.
Phenol formed as by-product of the decomposition may be removed or may be directly used in admixture with the product.

(2) In a second method isopropenylphenol for conversion to the dimer is obtained as a by-product in the production of hydroquinone or resorcinol by oxidation followed by decomposition of diisopropylbenzene. The prime object of this method is to produce hydroquinone or resorcinol, but the formation of m-or p-isopropenyl-phenol and m- or p-isopropylphenol as by-products is unavoidable in this method.

(3) In a third method, propylphenol (produced generally by propylation of phenol with propylene) is dehydrogenated and iscp ~ enylphenol and an oligomer thereof are obtained. O-, m- and p-isomers can be obtained singly or in the fo~m of a mixture.
A typical method for conversion of isopropenyl-phenol monomer to the dimer consists of heating p-isopropenylphenol for one hour at 125C, then cooling to 115-120C, while stirring, whereby the compound is gradually solidified to form a yellow mass. The product is then dissolved in toluene and recrystallized in the usual manner, whereby white crystals are obtained (typical yield 70~
The crystals are the dimers represented by the following formula:

, . .. .

~ . . . . . . .
.

- lllAO90 3 C 2 C = CH2 (IV) OH OH
In the present invention, dimers of the above recited formulae are essentially used as the phenol component of the resin and may be used alone or, preferably, in admixture with isopropenylphenol monomer or an oligomer thereof, which resin may then be used in the manufacture of laminates of superior mechanical and electrical characteristics. The dimer may also be used jointly with other ~;nown phenolic compounds, e.~., phenol; alkylphenols having alkyl group of C1 to C20, such as, cresols, xylenols, ethylphenols, propylphenols, butylphenols, amylphenols, octylphenols, nonylphenols and dodecylphenols; phenylphenols;
cumylphenols; ctyrenized phenol; and polyhydric phenols such as Bisphenol A, catechol and resorcinol. In addition to the phenolic compounds, polyglycolic subst~nces, drying oils having unsaturated bonds (such as tung oil, cashewnut oil ; and linseed oil) rosin, resol-type or novolac-type initial condensation products of a phenol with an aldehyde, as well as a mixture of these substances can be used jointly in the preparation of the phenol resin of this inventian.
Examples of the aldehyde component used in the present invention include formaldehyde formalin, paraformal-~ ..

. - .. .. ... . . ..

4~9-1 dehyde and equivalent compounds capable of releasing formaldehyde by heating.
A catalyst used for the production of the resol-; type phenol resin of this invention is a basic one such as a caustic alkali, ammonia or an amine. Such basic catalyst can be used singly or in admixture of at least two according to the purpose intended. The catalyst may be employed usually in an amount of 0.1 to 3% based on the starting phenol component. The reaction is carried out in the presence of water or of an organic solvent such as aliphatic alcohols, acetone, dioxanes or the like. The reaction temperature is usually within the range of about 50 to ~ 100C while the reaction time is within the range of about ; 1 to 15 hours, usually 2 to 6 hours. The molar ratio of the ~ldehyde component to the phenol component is typically between 0.3 and 1.5, usually between 0.7 and 1.4. After completion of the reaction, the catalyst is neutralized, i necessary, and thereafter the water or organic solvent is distilled off under reduced pressure to obtain the -~
resol-type phenol resin of the present invention. A
, varnish of the resol-type resin is obtained by adding a suitable vehicle such as an alcohol, a ketone, aromatic hydrocarbon or the like to the phenol resin. The varnish includes the vehicle in amounts of from 20 to 90% by weight.
A laminate is manufactured by impregnating a suitable base such as paper, fabric, asbestos or glass fiber with the ; varnish and heating the impregnated base to effect curing of the resin. The laminate contains the resin in amounts of from 25 to 60~, preferably from 30 to 50% by weight.
The present invention will now be illustrated in more detail by way of examples J9, ' .

11141~0 Comparative (control` Exam le P
In a reaction vessel were placed 94g of phenol, 70g of nonylphenol, 137g of 37% formalin and Sg of 28~
aqueous ammonia. The mixture was reacted under agitation for 5 hours at 95C. After completion of the reaction, the reaction mixture was dehydrated under reduced pressure and the dehydration treatment was stopped when the inner temperature reached 90C. The reaction mixture was cooled and methanol was added thereto to prepare a varnish having a resin content of 40%. A sheet of cotton linter paper was impregnated with the varnish and dried to form a base containing 45% by weight of the resin. Ten sheets of the base and an adhesive-attached copper foil were piled up and pressed for 50 minutes at 160C and 100 kg/cm2 pressure whereby a copper-clad laminate of 1.5mm in thickness was obtained. The physical properties of the laminate are shown in Table 1.
Example 1 Using 94g of phenol, 70g of nonylphenol, 49g of ; 20 p-isopropenylphenol dimer (a mixture of 90% pentene-l isomer and 10% pentene-2 isomer) of the following structures:

HO V C - CH - C ~ OH Penténe-l dimer .~ , .

HO ~ C = CH - C ~ OH Pentene-2 dimer, 17~g of 37% formalin and 6.4g of 28~ aqueous ammonia for the reaction. The mixture was reacted under agitation for

5 hours at 95C. After completion of the reaction, the .

1~ ~ 4(~0 reaction mixture was dehydrated under reduce~ pressure and the dehydration treatment was stopped when the inner temperature reached 90C. The reaction mixture was cooled and methanol was added thereto to prepare a varnish having a resin content of 40~. A sheet of cotton linter paper was impregnated with the varnish and dried to form a base containing 45% by weight of the resin. Ten sheets of the base and an adhesive-attached copper foil were piled up and pressed for 50 minutes at 160C and 100 kg/cm2 pressure whereby a copper-clad laminate of 1.5mm in thickness was obtained. The physical properties of the laminate are shown in Table 1.
Example 2 Using 94g of phenol, 70g of nonylphenol and 49g of a mixture of p-isopropenylphenol and oligomers thereof (containing, in terms of molecular weight distribution, 5~ monomer, 70% dimer, 10% trimer and 15% tetramer and higher oligomers), 174g of 37% formalin and 6.4g of 28 aqueous ammonia for the reaction, the reaction and the subsequent treatments as well as the preparation of a copper-clad laminate were carried out in the same manner as described in Example ]. The physical properties of the resultant laminate are shown in Table l.
Example 3 In a reaction vessel were placed 94g of phenol, 70g of nonylphenol, 6.0g of p-isopropenylphenol dimer (having the same composition as described in Example l), 140.3g of 37% formalin and 5.lg of 28% aqueous ammonia. The reaction and the subsequent treatments as well as the preparation of a copper-clad laminate were carried out in the same manner as described in Example 1. The physical , ., ' : . ' : : .

4(3~n properties of the resultant laminated plate are shown in Table l.
Of the testing methods for the various physical properties of the copper-clad laminates, the one for punching quality was performed according to ASTM D617-44 standards and the others according to JIS C-6481-1968 standards.

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Claims (6)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A resol-type phenol resin for laminates and the like comprising the product of a basic-catalyst-catalyzed reaction of a dimer of isopropenylphenol of the formula selected from and as an essential phenol component with an aldehyde, said dimer being contained in an amount from about 2 to about 60 weight % based on the total weight of the phenol com-ponents of said resin.

2. The resol-type phenol resin according to claim 1 wherein said aldehyde component of said resin is formaldehyde.

3. A laminate consisting of a plurality of super-posed bases impregnated with said resol-type phenol resin of claim 1.

4. The laminate according to claim 3 wherein said base is impregnated with a resol-type phenol resin made with formaldehyde and isopropenylphenol dimer.

5. The resol-type phenol resin according to claim 1 further including a vehicle selected from alcohols, ketones and aromatic hydrocarbons in an amount of from 20 to 90% by weight.

6. The resol-type phenol resin according to claim 5 wherein said resin is made with formaldehyde and isopropenylphenol dimer.