JP2011122009A - Drying oil-modified resol type phenolic resin, phenolic resin composition, prepreg, and laminated board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drying oil-modified resol type phenolic resin that has little unreacted phenol and aldehyde and has excellent flexibility and little odor; a prepreg; and a laminated board. <P>SOLUTION: The drying oil-modified resol type phenolic resin having little unreacted phenol, such as 1% or less, is obtained by performing an addition reaction of a low molecular weight novolak type phenolic resin having a number-average molecular weight of 600 or less and an unreacted phenol content of 2% or less to drying oil, such as tung oil, linseed oil, dehydrated castor oil under an acid catalyst and then by reacting aldehydes therewith in the presence of an alkali catalyst. The prepreg and the laminated board are obtained by impregnating a paper substrate with the phenolic resin composition including the drying oil-modified resol type phenolic resin as a principal component. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a drying oil-modified resol type phenol resin, a phenol resin composition, a prepreg, and a laminate.

Phenol resin, which is a thermosetting resin, has excellent adhesion to various substrates, and its cured product is also excellent in heat resistance, electrical insulation, solvent resistance, etc. Used in many industrial fields including electronic parts. However, since the cured product is rigid and fragile, techniques for blending or modifying various flexibility-imparting agents are used in fields of application where bending flexibility needs to be imparted.
For a long time, the use of drying oils such as paulownia oil, linseed oil, castor oil, etc. as typical representative modifiers has been put into practical use to improve flexibility, and it is mounted on electronic devices that place particular emphasis on punching processability. In printed circuit board laminates, the application of resins with a high blending ratio of the dry oil-modified resol type phenolic resin has been widely applied to impart flexibility.
Furthermore, many measures for improving the dry oil-modified phenol resin composition have been proposed in order to improve various properties of the laminate. (For example, described in Patent Documents 1 and 2.)

On the other hand, when synthesizing a resol type phenol resin, not a little unreacted phenol and formaldehyde remain.
In particular, in a dry oil-modified resol type phenolic resin, a large amount of unreacted phenol remains because the mixing ratio of phenols to the dry oil is excessive due to the reaction mechanism.
By increasing the formaldehyde ratio relative to phenol, the amount of unreacted phenol can be reduced somewhat, but on the other hand, the amount of unreacted formaldehyde increases and the odor becomes stronger.
For this reason, in laminates that make heavy use of dry oil-modified phenolic resin that emphasizes punching processability, there is a specific odor derived from the remaining unreacted phenol component, especially in the United States, etc. . In addition, when an electronic device or the like is used for a long time, there is a problem that the temperature of the device rises and phenol and formaldehyde are more easily released.

JP-A-6-320697 JP-A-5-148336

An object of the present invention is to provide a dry oil-modified resol type phenolic resin which is low in unreacted phenol and formaldehyde and excellent in flexibility.
Another object of the present invention is to provide a phenol resin composition, a prepreg, and a laminate that are low in unreacted phenol and formaldehyde, have low odor, and are excellent in flexibility.

Such an object is achieved by the present invention described in the following (1) to (4).
(1) A low molecular weight novolak type phenol resin having an unreacted phenol content of 2% or less and a number average molecular weight of 600 or less is added to a dry oil under an acidic catalyst, and then aldehydes in the presence of an alkali catalyst. A dry oil-modified resol-type phenolic resin characterized in that the amount of unreacted phenol obtained by reacting is less than 1%.
(2) A phenol resin composition comprising 30 to 80% by weight of the drying oil-modified resol type phenol resin described in (1) above.
(3) A prepreg comprising a paper base material impregnated with the phenol resin composition described in (2) above.
(4) A laminate comprising at least one prepreg according to (3) above.

  It is possible to provide a low-odor dry oil-modified resol type phenol resin, a phenol resin composition, a prepreg, and a laminated board that are low in unreacted phenol and formaldehyde and excellent in flexibility.

Hereinafter, the drying oil-modified resol type phenol resin, the phenol resin composition, the prepreg and the laminate of the present invention will be described in detail.
The drying oil-modified resole phenolic resin of the present invention is a drying oil-modified resole phenolic resin containing 1% or less of unreacted phenols.
Moreover, it is a phenol resin composition used in order to manufacture a phenol resin laminated board by using this as a main component.
The prepreg of the present invention is obtained by impregnating a paper base material with the above-described phenol resin composition.
In addition, the laminate of the present invention is obtained by superposing and heating at least one prepreg as described above.

First, the drying oil-modified resol type phenol resin of the present invention will be described.
The drying oil-modified resol type phenolic resin of the present invention is used for producing a paper base phenolic resin laminate (laminate) and the like.
For general drying oil-modified resol type phenolic resins, dry oil such as tung oil is subjected to an addition reaction of phenols such as phenol and cresol under an acidic catalyst, and then subjected to a polycondensation reaction by blending formaldehyde under an alkaline catalyst. The molecular weight is adjusted.
By adjusting the blending amount of formaldehyde and alkali catalyst, a phenol resin with excellent curability and flexibility can be obtained, but even if the reaction conditions are adjusted, all the phenols blended at the initial stage of the reaction are efficiently consumed. It cannot be made to remain, and remains in the resin as a large amount of unreacted components.
The main component of the phenol resin composition of the present invention, which is a dry oil-modified resol type phenol resin having 1% or less of unreacted phenol, is a low oil whose dry oil contains 2% or less of unreacted phenol and a number average molecular weight of 600 or less. A molecular novolak-type phenol resin, preferably a low-molecular novolak-type phenol resin having an unreacted phenol content of 1% or less and a number average molecular weight of 500 or less is reacted, and then a polycondensation reaction is performed by adding formaldehyde under an alkali catalyst. Can be obtained.
This low-molecular novolak type phenolic resin with 2% or less of unreacted phenols has a ratio of formaldehyde to phenols (charge molar ratio) of 0.7 or less, and evaporates unreacted phenols remaining after the reaction under high temperature and reduced pressure. Or an organic phosphonic acid as exemplified in JP-A-2002-194041 can be obtained as a catalyst.

In order to apply to the addition reaction with drying oil, this low molecular weight novolac type phenol resin is dissolved in a small amount of a polar solvent such as methanol in advance to prepare a phenol resin solution having a concentration of 80 to 90% by weight. Instead, by adding this novolac type phenol resin solution and applying it to the reaction with the drying oil under an acidic catalyst, a dry oil addition reaction phenol resin having 1% or less of unreacted phenol can be obtained. Although it does not specifically limit as said acidic catalyst, Organic acids like p-toluenesulfonic acid, xylenesulfonic acid, methanesulfonic acid, perfluoromethanesulfonic acid are mentioned, These should be used individually or in combination of 2 or more types. Can do.
When the number average molecular weight of the novolak resin exceeds 600, the solution viscosity becomes high and the addition reaction with the drying oil is remarkably reduced. Therefore, the number average molecular weight of the novolak resin is preferably 600 or less.

In this reaction process, in order to reduce the viscosity of the reaction system and facilitate a uniform reaction between the drying oil and the novolak type phenol resin, a non-polar fragrance such as toluene having excellent solubility in both the drying oil and the generated addition reaction product. A group hydrocarbon solvent can be appropriately blended.
The amount of the solvent is not particularly limited. However, if the amount is too small, the low viscosity effect is poor. If the amount is too large, the addition reaction is suppressed. Therefore, the amount is 10 to the total amount of the drying oil and the novolac type phenol resin solution. 30% by weight is preferred.
The reaction temperature and time applied to the addition reaction are not particularly limited, and the same conditions as those used for the addition reaction between general drying oil and phenols are applied. For example, the temperature is about 60 to 100 ° C. for about 1 to 4 hours.

Next, an alkaline catalyst such as amines and aqueous ammonia is added to change the reaction system from acidic to alkaline, then formaldehyde such as formalin and paraformal is added and reacted, dehydrated under reduced pressure if necessary, and diluted with an appropriate solvent. A dry oil-modified resol-type phenol resin can be obtained. In order to reduce the dehydration process time or eliminate the dehydration process, it is preferable to apply a high concentration of paraform.
The mixing ratio of formaldehyde to the novolac type phenol resin addition reaction product in the above drying oil is not particularly limited, but if the amount of formaldehyde is too small, the condensation reaction will not proceed and the curability will be inferior, and if it is too large, a large amount of unreacted formaldehyde will remain. This is not preferable. The recommended suitable blending ratio is 0.6 to 1.5, preferably 0.8 to 1.2 in terms of the molar ratio of formaldehyde to blended novolak resin.

As the solvent to be diluted, in order to obtain a uniform solubility of the reaction product, a mixture of an alcohol-based or ketone-based polar solvent and a non-polar aromatic hydrocarbon solvent such as toluene is suitable. In the weight ratio of (solvent) / (nonpolar aromatic hydrocarbon solvent), 1/3 to 3/1, preferably 1/2 to 2/1 is particularly recommended.
The dry oil-modified resol-type phenol resin obtained under such reaction conditions has very little unreacted phenol of 1% or less.

Next, the phenol resin composition of the present invention will be described.
In the production of laminates, the use of a plurality of characteristic phenolic resins in combination is widely performed in order to meet various required applications.
The resol type phenol resin used in combination with the drying oil-modified resol type phenol resin of the present invention is not particularly limited, and those usually used can be used.
In particular, by including a low-viscosity unmodified resol type phenolic resin, it is possible to improve the impregnation property of paper and to ensure appropriate hardness and heat resistance.
In addition, the cost of the laminated plate can be reduced.
However, in order to keep the unreacted phenol in the entire phenol resin composition small, it is useful that the unreacted phenol used in combination with the unmodified resol-type phenol resin used in combination is as small as possible.

  The content of the drying oil-modified resol type phenol resin in the phenol resin composition of the present invention is preferably 30 to 80% by weight, more preferably 35 to 65% by weight. When the content of the dry oil-modified resol type phenol resin is less than the lower limit, the flexibility and the flexibility are inferior, and the punching processability is insufficient. Moreover, when content of drying oil modified phenol resin exceeds the said upper limit, flexibility is too high and heat resistance and sclerosis | hardenability may fall.

In addition, a flame retardant compound such as a halogen compound, a phosphorus compound, or an amino resin can be blended within a range not departing from the object of the present invention.
Although content of the said flame-retardant compound is not specifically limited, 5 to 40 weight% of the whole phenol resin composition is preferable, More preferably, it is 10 to 30 weight%. Thereby, a flame retardance can be improved, without impairing the characteristic of a laminated board. Examples of the halogen compound include tetrabromobisphenol A (TBBA) and TBBA type flame retardant epoxy resin.

  Examples of phosphorus compounds include phosphate esters, condensed phosphate esters, and phosphine oxides. Examples of phosphate esters include triethyl phosphate, tributyl phosphate, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, resorcyl diphenyl phosphate, triisopropyl phenyl phosphate, and the like. Is used as one or a mixture of two or more. Among these, at least one phosphorus compound selected from triphenyl phosphate, tricresyl phosphate, and cresyl diphenyl phosphate is preferable in terms of availability.

  The amino resin is, for example, a melamine resin or a guanamine resin, but a melamine resin is preferable in order to enhance the effect of flame retardancy. The amino resin is an initial reaction product of an amino compound such as melamine or guanamine and an aldehyde such as formaldehyde, and some of these methylol groups are etherified with a lower alcohol such as methanol or butanol. .

  Next, the prepreg will be described.

The prepreg of the present invention is formed by impregnating a paper base material with the above-described phenol resin composition.
Examples of the paper substrate include craft paper and linter paper. Moreover, what was previously processed with water-soluble phenol resin, methylol melamine resin, etc. as a paper base material is also contained in this invention.
As a method of impregnating the paper base material with the phenol resin composition, a commonly used method can be used. For example, a method of impregnating a paper base material into a resin varnish, a method of applying with various coaters, a spraying method by spraying, and the like can be mentioned.

  Next, a laminated board is demonstrated.

The laminate of the present invention contains at least one prepreg.
When the laminate is a single prepreg, the laminate can be obtained by laminating a metal foil on one side or both sides thereof.
When two or more prepregs are used, the prepreg can be obtained by laminating a metal foil on one or both sides of the outermost side of the prepreg.
Examples of the metal constituting the metal foil include copper, a copper-based alloy, aluminum, an aluminum-based alloy, and the like. Of these, copper is preferably used as the metal foil.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited to this. In the description, “%” indicates “% by weight”, and “parts” indicates parts by weight.

[Production of drying oil-modified resol type phenol resin X]
A low molecular novolak type phenol resin (number average molecular weight 350, unreacted phenol 0.7%) exemplified in JP-A-2002-194041 was dissolved in methanol to prepare a novolak solution A having a concentration of 85%.
A 3 L three-necked flask was reacted for 3 hours at 85 ° C. using 500 parts of Tung oil, 750 parts of the above-mentioned novolak solution A, 200 parts of toluene, and 5 parts of paratoluenesulfonic acid as a catalyst, and then 10 parts of triethylamine and 75 parts of 92% strength paraformaldehyde. , 10 parts of 28% ammonia water was added and reacted at 80 ° C. for 2 hours, and then diluted with 750 parts of a mixed solvent of toluene and methanol (toluene / methanol = 1/2, weight ratio) to modify a dry oil having a resin content of 50%. A resol type phenol resin X was obtained.
This resin had a number average molecular weight of 950 and an unreacted phenol content of 0.3%.

[Production of drying oil-modified resol type phenol resin Y]
After reacting phenol (P) and formaldehyde (F) at a reaction molar ratio (F / P) of 0.65 at 100 ° C. for 3 hours using succinic acid as a catalyst, vacuum dehydration to an internal temperature of 200 ° C. and low molecular weight novolak type A phenol resin (number average molecular weight 480, unreacted phenol 0.9) was produced. This was dissolved in methanol to prepare a novolak solution B having a concentration of 82%.
The novolak solution B was reacted under the same conditions as the phenol resin X to obtain a dry oil-modified resol type phenol resin Y having a resin content of 50%.
This resin had a number average molecular weight of 710 and an unreacted phenol content of 0.4%.

[Production of drying oil-modified resol type phenol resin Z]
1600 g of phenol and 1000 g of tung oil were reacted at 95 ° C. for 2 hours in the presence of paratoluenesulfonic acid, and further 650 g of paraformaldehyde, 30 g of hexamethylenetetramine and 2000 g of toluene were added and reacted at 90 ° C. for 2 hours, and then concentrated under reduced pressure. This was diluted with a mixed solvent of toluene and methanol to obtain a dry oil-modified resol type phenol resin Z having a resin content of 50%.
This resin had a number average molecular weight of 290 and an unreacted phenol content of 18%.

[Production of Unmodified Resol Type Phenolic Resin A]
A mixture of 1000 g of phenol, 1510 g of 37% formaldehyde aqueous solution and 60 g of triethylamine was reacted at 80 ° C. for 2 hours, then dehydrated and concentrated under reduced pressure, diluted with 700 g of methanol, and unmodified resole phenol having a resin content of 50%. Resin A was obtained.
This resin had a number average molecular weight of 250 and an unreacted phenol content of 9.5%.

[Preparation of resin varnish XA for paper substrate impregnation]
The values in parentheses are shown in terms of solid content excluding the solvent.
75 parts by weight (23%) of the above-mentioned unmodified resol type phenolic resin varnish A, 165 parts by weight (50%) of drying oil modified resol type phenolic resin varnish X, TBBA type flame retardant epoxy resin (GX-153 Dainippon Ink, Ltd.) Chemical Industry Co., Ltd.) 10 parts by weight (6%), triphenyl phosphate (TPP, manufactured by Daihachi Chemical Co., Ltd.) 20 parts by weight (12%), methylolated melamine resin (Phenolite TD-2538, Dainippon Ink) A resin varnish XA for impregnation with a paper base material was obtained by blending 30 parts by weight (9%) (resin content: 50%, manufactured by Chemical Industry Co., Ltd.).

[Preparation of resin varnish YA for paper base impregnation]
Similarly, 75 parts by weight (23%) of unmodified resol type phenolic resin A and 165 parts by weight (50%) of drying oil-modified resol type phenolic resin Y were blended in the same manner as described above to form resin varnish YA for impregnating paper base material. Got.

[Preparation of resin varnish ZA for paper substrate impregnation]
Similarly, 75 parts by weight (23%) of unmodified resol type phenolic resin A and 165 parts by weight (50%) of dry oil-modified resol type phenolic resin Z are blended in the same manner as described above to form resin varnish ZA for impregnating paper base material. Got.

Example 1
[Manufacture of laminates]
A prepreg was obtained by impregnating the above-mentioned resin varnish XA for impregnating the paper substrate with the paper substrate so that the resin impregnation rate was 55% (ratio to the whole prepreg). Eight of the prepregs and both front and back surfaces of the copper foil with adhesive (FSM manufactured by Nippon Electrolytic Co., Ltd.) were overlaid and heated and pressed at 150 ° C., 10 MPa for 120 minutes to obtain a 1.6 mm thick laminate.

(Example 2)
A laminate was obtained in the same manner as in Example 1 except that the resin varnish XA for impregnating the paper base material was changed to the resin varnish YA for impregnating the paper base material.

(Example 3)
A laminated board was obtained in the same manner as in Example 1 except that the resin varnish XA for impregnating the paper base material was changed to the dry oil-modified resol type phenol resin X.

(Comparative Example 1)
A laminated board was obtained in the same manner as in Example 1 except that the resin varnish XA for impregnating the paper base material was changed to the resin varnish ZA for impregnating the paper base material.

(Comparative Example 2)
The same procedure as in Example 1 was conducted except that the resin varnish XA for impregnating the paper base material was changed to only the unmodified resol type phenol resin varnish A.

  Each characteristic of the laminated board obtained by the above-mentioned Example and comparative example was evaluated with the following method. The obtained results are shown in Table 1.

(1) Flame retardancy It evaluated according to UL94 method.
(2) Punching workability Measured based on ASTM D617-44. Each symbol is as follows.
○: No resin chipping or copper foil peeling at the end face of the laminate. Little generation of resin powder.
Δ: Resin chipping and copper foil peeling off at the end face of the laminate, but the generation of resin powder is small.
X: There are resin chipping and copper foil peeling at the end face of the laminate, and resin powder is often generated.
(3) Phenol elution amount It measured based on JISK0102.
(4) Formaldehyde emission amount Measured based on the JAS desiccator method.
A predetermined amount of the laminated plate was put in a sealed glass desiccator, and allowed to stand at 20 ° C. for 24 hours to absorb the diffused formaldehyde in distilled water, and the concentration was measured by the acetylacetone absorbance method.

  In Examples 1 to 3, both flame retardancy and punching workability were good, and there were very few unreacted components and low odor. On the other hand, in the general dry oil modified phenol resin application product of Comparative Example 1, The amount of elution was high. When the drying oil-modified phenol resin of Comparative Example 2 was not applied, the amount of phenol elution was not so high, but the punching processability was extremely low.

Claims (4)

A low molecular weight novolak type phenol resin having an unreacted phenol content of 2% or less and a number average molecular weight of 600 or less is subjected to an addition reaction with a dry oil under an acidic catalyst, and then an aldehyde is reacted in the presence of an alkali catalyst. A dry oil-modified resol-type phenolic resin obtained by drying and having a low unreacted phenol content of 1% or less. A phenol resin composition comprising 30 to 80% by weight of the drying oil-modified resol type phenol resin according to claim 1. A prepreg comprising a paper base material impregnated with the phenol resin composition according to claim 2. A laminate comprising at least one prepreg according to claim 3.