JPH0212970B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a phenolic resin used as an impregnating resin for laminates and copper-clad laminates. Recently, laminates and copper-clad laminates used as insulating materials in consumer electronic devices have been improved in terms of punching workability at room temperature or relatively low temperatures around room temperature, from the viewpoint of automating processing equipment and saving labor. Excellence is required. For this reason, phenol formaldehyde resin modified with drying oil is used. However, since the curing speed is slow and the crosslinking density is reduced due to modification by the drying oil, the resin in the laminate tends to be insufficiently cured and properties such as heat resistance and solvent resistance are reduced. Furthermore, during punching, interlayer peeling is likely to occur due to the low crosslinking density. Conventionally, when producing phenolic resin by reacting drying oil and phenol, then reacting with formaldehyde, and dehydrating under reduced pressure, the reaction with formaldehyde produces condensed water, which tends to result in a heterogeneous reaction, resulting in a resin-forming reaction, In the curing reaction, the reaction rate and curing rate are reduced, which causes deterioration of various properties. As a countermeasure for this, a solvent such as methanol is added to ensure a homogeneous reaction, but during the vacuum dehydration process, the added solvent is also removed from the system over time, resulting in a heterogeneous reaction, which is not sufficient. . The present invention was made in view of these points, and after reacting drying oil with phenol and further reacting with formaldehyde, an external substance that is not reactive with the drying oil, phenol, formaldehyde, and their reaction products is added. It is characterized in that a plasticizer is added and a resin formation reaction is carried out while dehydrating under reduced pressure in the presence of an external plasticizer. Normally, drying oil-modified phenolic resin is produced by reacting drying oil and phenol under an acidic catalyst such as para-toluenesulfonic acid, _BF3 phenol complex salt, and sulfuric acid at a temperature of 60°C.
React under the conditions of ℃ to 170℃ for 30 minutes to 5 hours. Next, formaldehyde is added, a solvent such as methanol is added, and the reaction temperature is increased under a basic catalyst such as ammonia.
It is produced by conducting the reaction at 60°C to 100°C for 30 minutes to 6 hours, and then dehydrating it under reduced pressure at a reaction temperature of 50°C to 100°C for 30 minutes to 6 hours. The present invention involves reacting drying oil with phenol and then reacting with formaldehyde while dehydrating under reduced pressure in the presence of an external plasticizer that does not react with drying oil, phenol, formaldehyde, and their reaction products. It is characterized by carrying out a resin formation reaction. Here, the external plasticizer is added from the outside to impart and improve the plasticity of the substance, and the external plasticizer in the present invention refers to cresyl diphenyl phosphate, triphenyl phosphate, and tricresyl phosphate. Phthalate esters such as dimethyl phthalate and diethyl phthalate, polyglycol esters, and oxyacid esters. The external plasticizer is added in the step of carrying out the resin formation reaction while dehydrating under reduced pressure. For 95 to 60 parts by weight of drying oil and phenol, 5 to 40 parts by weight of external plasticizer are used. The effect of the external plasticizer is that it has moderate polarity and is compatible with various polymeric substances, so it is presumed that the reaction system becomes more uniform. As the drying oil, tung oil, linseed oil, dehydrated castor oil, tall oil, oitinca oil, etc. are used. As the phenol, phenol, metacresol, para-cresol, orthocresol, para-isopropyl phenol, para-tertiary butyl phenol, oligomer of para-isopropenyl phenol, nonylphenol, bisphenol A, etc. are used. The dry oil-modified phenolic resin obtained in this way has good reactivity and hardenability, and is dissolved in organic solvents such as acetone, methyl ethyl ketone, and methyl cellosolve to form a varnish and impregnated into a base material to form a phenolic resin laminate. used in the production of Example 1 87.3 g of tung oil, 141 g of metacresol, and 0.08 g of p-toluenesulfonic acid were mixed and reacted at 110° C. for 1 hour. To this reaction product, 41 g of paratertiary butylphenol, 60 g of paraformaldehyde,
20 g of methanol and 6 g of 25% aqueous ammonia were placed in a reaction vessel and reacted at 80°C for 3 hours. Next, 23 g of cresyl diphenyl phosphate was placed in a reaction vessel, and water was removed from the reaction solution under reduced pressure (620 mmHg). As dehydration progresses, the liquid temperature gradually increases, and 55
When the temperature reaches ℃, the reactants become transparent. Subsequently, dehydration was carried out, and when the gel time reached 3 minutes and 30 seconds, dehydration was stopped, the mixture was rapidly cooled, and the mixture was dissolved in a mixed solvent of methanol and acetone (1:1) to produce a 50% by weight resin varnish. Cotton linter paper, which had been previously undercoated with a water-soluble phenol formaldehyde varnish for undercoating, was impregnated with the above varnish and dried to obtain a prepreg with an adhered resin content of 50% by weight. A predetermined number of these sheets were stacked and heated and pressed for 60 minutes under lamination conditions of 160 to 165° C. and 80 kg/cm ² to obtain a laminate with a thickness of 1.6 mm.
The properties of this laminate are shown in the attached table. Comparative Example 87.3 g of tung oil, 141 g of metacresol, and 0.08 g of para-toluenesulfonic acid were mixed and reacted at 110°C for 1 hour. Add 41 g of paratertiary butylphenol, 60 g of paraformaldehyde, 20 g of methanol, and 6 g of 25% aqueous ammonia to this reaction mixture,
The reaction was carried out at ℃ for 3 hours. Next, water is removed from the reaction solution under reduced pressure. As the dehydration progresses, the temperature of the liquid gradually increases and it becomes transparent for a time, but as dehydration continues, the reaction liquid becomes non-uniform and opaque. A laminate was obtained using the same method as in the example. The properties of this laminate are shown in the attached table.

[Table] As is clear from the examples and comparative examples above, heat-resistant phenol-formaldehyde resin is produced by reacting drying oil with phenol, further reacting with formaldehyde, and dehydrating under reduced pressure in the presence of an external plasticizer. It is possible to produce a laminate with excellent properties such as hardness, solvent resistance, and punching workability.

Claims (1)

[Claims] 1. After reacting drying oil and phenol, and then reacting formaldehyde under a basic catalyst, an external plasticizer is added, and a resin-forming reaction is performed while dehydrating under reduced pressure in the presence of the external plasticizer. , the external plasticizer is non-reactive with drying oil, phenol, formaldehyde and their reaction products, and the solution to which the external plasticizer is added is a hydrophobic phenol-added drying oil-based compound and a hydrophilic compound. A method for producing a phenolic resin, characterized in that the solution is a heterogeneous solution containing a phenolic compound.