JPH0859860A - Production of flame-retardant phenol resin laminate - Google Patents

Abstract

PURPOSE: To obtain a flame-retardant phenol resin laminate excellent in electrical insulating properties and water absorption by impregnating a paper substrate with a phenol resin varnish contg. a specific flame retardant and then with a specific phenol resin varnish and laminating the impregnated substrate. CONSTITUTION: This laminate is produced by impregnating a paper substrate with a phenol resin varnish prepd. by compounding a low mol.wt. phenol resin with a water-sol. nitrogen flame retardant (e. g. a melamine resin), a reactive phosphorus flame retardant [e.g. tris(3-hydroxypropyl)phosphine oxide] or an additive phosphorus flame retardant (e.g. cresyl diphenyl phosphate), etc., and then with a phenol resin varnish contg. no bromine flame retardant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a paper-based phenolic resin laminate excellent in flame retardancy, electrical insulation and water absorption without using a brominated flame retardant.

[0002]

2. Description of the Related Art In a method for producing a thermosetting resin laminate using paper as a base material, there is a two-stage impregnation method as a method for impregnating a paper base material with a thermosetting resin. This method is a method in which a resin varnish having a good affinity with paper is impregnated as a pretreatment, dried and then impregnated with a thermosetting resin varnish.

As one of the methods for making a paper substrate laminate flame-retardant, a method of using a melamine resin or a melamine-modified phenol resin for a pretreatment varnish has been adopted. Further, as a method for improving the electrical characteristics and the water absorption rate, a method of using a water-soluble phenol resin or melamine resin for pretreatment is performed. However, although such a resin improves electric characteristics and water absorption, it is still insufficient in improving flame retardancy.

[0004]

A method of incorporating a halogen-based flame retardant into a resin varnish in order to improve the flame retardancy of a thermosetting resin laminate is generally performed and its effect has been confirmed. . However, since toxic gas is generated at the time of combustion, various methods have been studied that can sufficiently exhibit flame retardancy without using a halogen-based flame retardant or using a small amount thereof.

The present invention is a paper base flame retardant which is excellent in flame retardancy, electric insulation and water absorption without using halogen flame retardants by using a phosphorus varnish and a nitrogen flame retardant together with a pretreatment phenol varnish. An object of the present invention is to provide a method for producing a phenolic resin laminated board.

[0006]

According to the present invention, a paper base is impregnated with a phenol resin varnish prepared by blending a phosphorus-based flame retardant and a water-soluble nitrogen-based flame retardant in a low molecular weight phenol resin, and then a brominated flame retardant is used. The method for producing a flame-retardant phenolic resin laminate is characterized by impregnating a phenolic resin varnish for a laminate using a phosphorus-based flame retardant and a nitrogen-based flame retardant.

In the present invention, the phosphorus-based flame retardant includes a reactive phosphorus-based flame retardant and an addition-type phosphorus-based flame retardant. Examples of the reactive type include RDP (Ajinomoto), DRP (Ajinomoto), tris (3-hydroxypropyl) phosphine oxide, and the addition type includes cresyl diphenyl phosphate, triallyl phosphate, dimethyl methyl phosphate. Etc.

Since the reactive phosphorus flame retardant has a functional group that reacts with the phenol resin and reacts with the phenol resin during molding into a laminated board, the electrical characteristics of the laminated board under various treatment conditions are It does not deteriorate the characteristics such as water absorption. On the other hand, there are many types of addition-type phosphorus-based flame retardants, such as ones that do not easily deteriorate the laminated plate characteristics and ones that have large flame retardancy, and can be appropriately selected depending on the required characteristics and cost.

As the water-soluble nitrogen-based flame retardant, there are melamine resin, benzoguanamine resin, acetoguanamine resin and the like, but melamine resin is preferable in view of flame retardancy and cost. The low-molecular-weight phenol resin containing these flame retardants has a predetermined molar ratio of phenol compounds such as phenol, cresol, and xylenol to formaldehyde (usually, the molar ratio of formaldehyde to phenol is 1.5.
-2.5), reacted under an alkaline catalyst such as ammonia and amines, stopped in the initial water-soluble state, and diluted with water or an alcohol such as methanol as needed.

In the resin varnish for pretreatment, the mixing ratio of each component is such that the phosphorus-based flame retardant is a low molecular weight phenol resin 100.
40 to 80 parts by weight to 15 parts by weight of nitrogen-based flame retardant
0 to 200 parts by weight is preferable. If the amount of the phosphorus-based flame retardant is less than the above range, the flame retarding effect is small, while if it exceeds the above range, the electrical insulating property and the water absorption are lowered. When the amount of the nitrogen-based flame retardant is less than the above range, the flame retardant effect is small, while when it exceeds the above range, the punching property and the water absorption rate are deteriorated.

The resin content in the resin varnish for pretreatment is 5 to
It is about 20% by weight, and is adjusted by diluting with water or alcohol such as methanol. This pretreatment varnish is adjusted so that the resin content is 5 to 15% by weight based on the pretreatment prepreg. If it is less than 5% by weight, the effect on flame retardancy, electrical insulation and water absorption is small, and if it exceeds 15% by weight, the prepreg becomes hard and properties such as punching property deteriorate. The paper base material is impregnated with the pretreatment varnish prepared as described above and dried to obtain a pretreatment prepreg.

Next, the pretreated prepreg is impregnated with a flame-retardant phenol resin varnish for a laminated plate to obtain a prepreg. The flame-retardant phenol resin varnish is preferably a mixture of the ordinary phenol resin modified with a drying oil such as tung oil and the same flame retardant as used in the pretreatment. The resin content of this varnish is usually about 40-60% by weight. This flame-retarded phenol resin varnish impregnates the paper base material and when dried, has a total resin content of 40-6.
Adjust to 0% by weight. A predetermined number of the prepregs thus obtained are superposed, copper foil is superposed on one side or both sides of the prepreg, if necessary, and heat-pressed to obtain a flame-retardant phenolic resin laminate.

[0013]

In the method for producing a laminated sheet of the present invention, a two-stage impregnation technique is adopted, and a phosphorus bromine flame retardant and a water-soluble nitrogen flame retardant are used in combination in a phenol varnish for pretreatment, whereby a brominated flame retardant is used. It is possible to obtain a phenol resin laminated plate which has excellent flame retardancy and generates less harmful gas even though it is not used. In addition, since the phenol resin is used for the pretreatment, the electric characteristics and the water absorption rate do not decrease. In particular, by using a melamine resin as the reactive phosphorus-based flame retardant and the water-soluble nitrogen-based flame retardant, each of the above properties can be further improved.

[0014]

Embodiments of the present invention will be described below. First, Table 1
A varnish for pretreatment was prepared with the composition shown in. The resin content was 10% (weight% or less, the same) with a mixed solvent of water and methanol (weight ratio 1: 1). Kraft paper was impregnated with this varnish so that the resin content was 10% and dried to obtain a pretreated prepreg.

[0015]

[Table 1]

Then, a varnish made of tung oil-modified phenol resin containing 10% of an additive type phosphorus flame retardant and 30% of a nitrogen flame retardant as a flame retardant is impregnated and dried to a total resin content of 50%, and then prepreg is prepared. Got 8 pieces of this prepreg and copper foil on one side are stacked, and 100 Kg / cm ² ,
Pressure molding was performed at 180 ° C. for 90 minutes to obtain a single-sided copper-clad laminate.

Table 2 shows the characteristics of the obtained laminated plate. In Comparative Example 2, the pretreatment varnish used in Example 3 and the tung oil-modified phenolic resin were mixed at a ratio of 1: 4 (resin solid content ratio) without pretreatment, and the varnish was contained in the total resin content. 5
A prepreg was obtained by impregnating it to 0% and drying, and then a single-sided copper-clad laminate was obtained in the same manner.

[0018]

[Table 2]

(Measurement method) 1. Flame retardance: UL-94 V-0 2. Insulation resistance, water absorption rate: JIS C 6481 3. Tracking resistance: IEC method

From the above results, the laminates obtained in the examples are excellent in flame retardance despite not containing a brominated flame retardant, and also have good electrical insulation, tracking resistance and water absorption. is there. Comparative Example 1 is inferior in flame retardancy, and Comparative Example 2 is inferior in flame retardancy and tracking resistance.

[0021]

EFFECTS OF THE INVENTION The flame-retardant phenolic resin laminate obtained by the method of the present invention is excellent in flame retardancy as well as various characteristics such as electric characteristics and water absorption.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area C08L 61/04 LMR

Claims (2)

[Claims] 1. A phenolic resin for a laminated board, wherein a paper base material is impregnated with a phenol resin varnish prepared by blending a water-soluble nitrogen flame retardant and a reactive phosphorus flame retardant in a low molecular weight phenol resin, and then a bromine flame retardant is not used. A method for producing a flame-retardant phenolic resin laminate, which comprises impregnating a varnish. 2. A phenolic resin for a laminated plate, wherein a paper base material is impregnated with a phenol resin varnish prepared by blending a water-soluble nitrogen-based flame retardant and an addition-type phosphorus-based flame retardant in a low-molecular-weight phenol resin, and then a bromine-based flame retardant is not used. A method for producing a flame-retardant phenolic resin laminate, which comprises impregnating a varnish.