JPS6223003B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a solid resol resin having improved performance, particularly for producing a non-ammonia benzyl ether type solid resol resin having significantly superior electrical insulation, heat resistance, and moisture resistance compared to conventional phenolic resins. It is about the method. Phenol resin, which was developed among the earliest plastics, has long been used in electrical parts and the like as a plastic material with good heat resistance and electrical properties. However, thermosetting resins such as unsaturated polyester resins, diallyl phthalate resins, and epoxy resins have been developed one after another and have come to be used in place of phenolic resins due to their superior electrical properties. In particular, as electrical technology progresses, plastic molding materials with superior electrical and physical properties are increasingly required, and the fields of use for phenolic resins are shrinking. Furthermore, with the advent of engineering plastics that have a certain degree of heat resistance and good electrical properties, their uses are gradually being taken away, and the demand for them is gradually declining. The biggest weakness of phenolic resins that led to this situation is that they have particularly low normal volume resistivity, and conventional phenolic resins have much lower resistance values than the high electrical resistance required in advanced electrical technology fields. This is only 3 to 4 orders of magnitude lower than the above-mentioned thermosetting resins, which have excellent electrical properties. The present inventors have improved the drawbacks of phenolic resins, which are industrially available at low cost, and have high normal volume resistivity and heat resistance that can be applied to parts in the advanced electrical technology field, and have excellent processability. As a result of repeated research to develop an excellent phenolic resin, we found that a benzylic ether-type solid resol resin, which reduces the amount of free phenol in the resin as much as possible and increases the crosslinking density of the resin as much as possible, has achieved the goal. This discovery led to the present invention. That is, the present invention involves heating and condensing phenols and 1 to 2 moles of aldehyde per mole of the phenol in the presence of a divalent metal salt of 0.1 to 2% by weight based on the weight of the phenols for 2 to 6 hours. A solid resol resin having a free phenol content of 2% by weight or less and a gel time of 180 to 480 seconds, which is obtained by reacting and then dehydrating at a temperature of 110 to 120°C and a degree of vacuum of 700 mmHg or more, and 30 parts by weight of this resin. When 65.5 parts by weight of crystalline silica, 3 parts by weight of magnesium oxide, and 1.5 parts by weight of zinc stearate are added to the molding material, the volume resistivity under normal conditions and boiling is ^10-14 Ω or more, and the volume resistivity when heated at a temperature of 180°C. Value 10 ¹¹ Ω or more, temperature 120℃, relative humidity 100
%, after 1000 hours at high temperature and high humidity, a volume resistivity of ^10-11 Ω or more, and a water absorption rate of 1.0% or less after 1000 hours at a temperature of 120°C and a relative humidity of 100%. The present invention provides a method for producing a liquid ether type solid resol resin. In the present invention, phenols for forming a non-ammonia benzyl ether type solid resol resin include phenol and its derivatives, and particularly preferred are phenol, cresol and xylenol. Moreover, formaldehydes such as formalin and paraformaldehyde are suitable as the aldehyde, and it is particularly preferable to use paraformaldehyde. In order to obtain the desired resin of the present invention, it is important to use the aldehyde in the reaction at a ratio of 1 to 2 moles per mole of the above phenols; if it deviates from this range, the purpose of the present invention cannot be achieved. . Further, the catalyst is not limited as long as it does not impair the electrical properties and physical properties of the resin formed by the reaction, but organic acid salts are preferably used, and zinc acetate, manganese acetate, and lead naphthenate are particularly advantageously used. These can be used alone or in combination of two or more. The divalent metal salt needs to be present in the reaction system in an amount ranging from 0.1 to 2 parts by weight per 100 parts by weight of the phenol. If it deviates from this range, a resin having desired excellent properties cannot be obtained. In the present invention, the above phenols, aldehydes, and divalent metal salts are mixed and subjected to a condensation reaction. The reaction temperature is not particularly limited, but reflux temperature is usually advantageously employed. The reaction time varies somewhat depending on the temperature and the mutual ratio and concentration of raw materials, but is in the range of 2 to 6 hours. After the condensation reaction, the reaction system was heated to a temperature of 110-120℃ and 700mmHg.
The desired solid resol resin can be obtained by performing dehydration treatment under higher reduced pressure conditions. The conditions for this dehydration treatment are extremely important, and if the combination of dehydration temperature and degree of vacuum is out of range, the desired resin cannot be obtained. More preferred ranges are a dehydration temperature of 110 to 115°C and a high degree of vacuum of 730 mmHg or higher. The resol resin obtained by the method of the present invention has a bond structure with more dimethylene ether groups than methylol groups and methylene groups, has an extremely low free phenol content, and has a melting point of about 60 to 70 ° C. The gel time is fairly long and the benzyl ether type solids do not generate undesirable ammonia. The amount of free phenols contained in the resin obtained by the process of the invention must be less than 2% by weight, preferably less than 1% by weight. If it exceeds 2% by weight, the gel time of the resin will be significantly shortened and sufficient roll kneading will not be possible during processing into a molding material, resulting in a large amount of volatile matter remaining in the resulting molding material, resulting in a decrease in the volume resistivity of the material. The value becomes low, which is not desirable. From this point of view, it is important that the gel time of the resin of the present invention is 180 seconds or more, and the practically desirable range is 240 to 480 seconds. If the gel time is longer than 480 seconds, the roll kneading time becomes too long, which slows curing of the resin and significantly reduces productivity, which is not preferable. The gel time here is a value measured by the method described in JIS K 6910, and the above free phenol content is a value measured by liquid chromatography. In addition, the solid resol resin obtained by the method of the present invention was prepared using the general method for evaluating phenolic molding materials, that is, 30 parts by weight of resin, crystalline silica
A molding material obtained by heating and kneading a composition consisting of 65.5 parts by weight, 3 parts by weight of magnesium oxide, and 1.5 parts by weight of zinc stearate using rolls heated to, for example, 85°C for 18 minutes, forming it into a sheet, cooling it, and pulverizing it. is normal, when the boiling volume specific resistance value is ^10-14 Ω or more,
It has a volume resistivity value of 10 ¹¹ Ω or more when heated at a temperature of 180°C, and a volume resistivity value of 10 ¹¹ when exposed for 1000 hours under atmospheric conditions of a temperature of 120°C and a relative humidity of 100%.
Ω or more and a water absorption rate of 1.0% by weight or less. The normal, boiling, and hot volume resistivity values of the above molding materials are measured based on JISK6911, and the volume resistivity values and water absorption rates at high temperature and high humidity are used to measure the physical properties of epoxy resin molding materials, etc. It was measured under the condition of 2 atmospheres according to the Plessia-Kutsker method. In addition, the crystalline silica used as the base material of the molding material is a curved base material for expressing the physical properties of the molding material using the resin obtained by the method of the present invention, and other base materials, such as Similar physical property values can be confirmed using aluminum silicate, calcined clay, glass, asbestos, calcium carbonate, mica, aluminum hydroxide, alumina, and the like. The solid resol resin obtained by the method of the present invention can be used as plastics for electrical parts that require high performance, and has significantly improved electrical insulation and heat resistance compared to conventional phenolic resins. It is possible to provide molding materials that are resistant to moisture and moisture. For example, a molding material obtained by using a novolak resin containing 2% by weight or less of free phenol, which is representative of conventional phenolic resins, and blending 30 parts by weight thereof with 65.5 parts by weight of a crystalline silica base material and the like, and the present invention. When compared with a molding material of similar composition obtained using the resin described above, the resin obtained by the method of the present invention has the following advantages. (1) Under normal conditions, the boiling volume resistivity value is 10 ¹⁴ Ω or more, which is 2 to 3 orders of magnitude (10 ² to 10 ³ Ω) higher. (2) The volume resistivity value at high temperatures is 10 ¹¹ Ω or more at 180°C, which is 3 orders of magnitude (10 ³ Ω) higher. (3) Moisture resistance, especially at 120℃ and 100% relative humidity.
After 1000 hours, the volume resistivity value is 10 ¹¹ Ω or more, which is two orders of magnitude (10 ² Ω) higher. (4) The water absorption rate was 1% by weight or less for the comparative material in 1000 hours at 120°C and 100% relative humidity, whereas it was less than 2% by weight for the comparative material.
% by weight or less. (5) It also has high heat resistance, and when measuring long-term weight changes at 180°C, the reduction rate is smaller than that of comparative materials. As described above, the resin obtained by the method of the present invention has significantly superior heat resistance, moisture resistance, and especially electrical insulation properties compared to novolak resins that represent conventional phenolic resins, and has excellent heat resistance, moisture resistance, and especially electrical insulation properties. It has physical properties comparable to resins. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Note that % and parts in the examples are by weight unless otherwise specified. Example 1 3000g of phenol in a 5-volume three-necked flask,
Add 1560 g of 92% paraform (molar ratio 1.5) and 12 g of zinc acetate, and after reacting for 4 hours at a reflux temperature of 115 to 103°C, dehydrate under reduced pressure at a dehydration temperature of 115°C and a degree of vacuum of 755 mmHg until the reaction product has the viscosity of a dehydrated product. At that point, the dehydration under reduced pressure was completed, and the dehydrated reaction product was taken out from the flask. The properties of the obtained resin are flow ∞, gel time
270 seconds, melting point 61°C, free phenol content 1.2%. Note that the flow and gel time are the values measured according to JISK6910, and the melting point is the value measured by the capillary method. (The same applies hereinafter) To 30 parts of this resin, crystal silica (MALVERN
MIN―ERALS CO Novasite) 65.5 parts, MgO3
After mixing, the mixture was mixed with 1.5 parts of zinc stearate, kneaded for 18 minutes using rolls heated to 85°C to form a sheet, cooled, and crushed to obtain a molding material. Various physical properties of this material are summarized in Table 1 below together with each example below. Example 2 Phenol 3000 in a 5-volume three-necked flask
g, 1250 g of 92% paraform (molar ratio 1.2) and 12 g of zinc acetate were added, and after reacting at a reflux temperature of 114 to 102 °C for 5 hours, dehydration was performed under reduced pressure at a dehydration temperature of 117 °C and a degree of vacuum of 755 mmHg, and the reaction product was dehydrated to the desired level. When the viscosity reached a solid level, the dehydration under reduced pressure was completed and the dehydrated reaction product was discharged from the flask. The properties of the obtained resin are flow ∞, gel time
350 seconds, the melting point was 64°C, and the amount of free phenol was 0.9%. A molding material was obtained in the same manner as in Example 1 using this resin. Comparative Example 1 3000g of phenol in a 5-volume three-necked flask,
Add 1560 g of 92% paraform (molar ratio 1.5) and 12 g of zinc acetate, and after reacting for 4 hours at a reflux temperature of 115 to 103°C, dehydration is performed under reduced pressure at a dehydration temperature of 115°C and a degree of vacuum of 600 mmHg, so that the reaction product reaches the desired viscosity of the dehydrated product. At the point at which the dehydration was completed, the dehydration under reduced pressure was completed, and the dehydration reaction product was discharged from the flask. The properties of the resulting resin were a flow of 120 mm, a gel time of 51 seconds, a melting point of 49° C., and a free phenol content of 4.6%. Using this resin, 85
The mixture was kneaded for 3 minutes using rolls heated to 0.degree. C. to form a sheet, and after cooling, it was crushed to obtain a molding material. Comparative Example 2 3000g of phenol in a 5-volume three-necked flask,
Add 1560 g of 92% paraform (molar ratio 1.5) and 12 g of zinc acetate and react at a reflux temperature of 115 to 103°C for 4 hours, then dehydrate under reduced pressure at a dehydration temperature of 130°C and a reduced pressure of 730 mmHg until the reactant reaches the desired dehydrated viscosity. At that point, the dehydration under reduced pressure was completed, and the escaped reaction product was discharged from the flask. The properties of the resulting resin were a flow of 147 mm, a gel time of 135 seconds, a melting point of 53° C., and a free phenol content of 3.2%. Using this resin, the same formulation as in Example 1 was used at 85°C.
The mixture was kneaded for 4 minutes using heated rolls to form a sheet, and after cooling, it was crushed to obtain a molding material. Comparative Example 3 3000g of phenol in a 5-volume three-necked flask,
2200 g of 37% formalin (molar ratio 0.85) and 18 g of oxalic acid were added, and after reacting for 3 hours at a reflux temperature of 102 to 101°C, dehydration was carried out under reduced pressure at a dehydration temperature of 175°C and a degree of vacuum of 700 mmHg for 2 hours, and the reaction product was discharged. The properties of the obtained resin are flow 86mm, gel time
The temperature was 48 seconds, the melting point was 74°C, and the amount of free phenol was 2.0% (all values for a 10% mixture of hexamethylenetetraamine). 26 parts of this resin, hexamethylenetetraamine
4.5 parts, crystalline silica (MALVERN MINERALS
After mixing, 65.5 parts of CO Novasite), 2.5 parts of MgO, and 1.5 parts of zinc stearate were mixed, kneaded for 6 minutes with rolls heated to 85°C to form a sheet, cooled, and then crushed to obtain a molding material. Comparative Example 4 Unsaturated polyester resin (Yupica manufactured by Nippon Upica)
8542) 21 parts, diallyl orthophthalate resin (Osaka Soda DAP-K) 9 parts, crystalline silica (MAL-
Novacyte manufactured by VERN MINERALS CO.) 67.6 copies,
1.2 parts of digyl peroxide and 1.2 parts of zinc stearate were blended and mixed, then kneaded for 12 minutes with rolls heated to 95°C to form a sheet, cooled and crushed to obtain a molding material. The physical properties of the molding materials obtained in Examples 1 to 2 and Comparative Examples 1 to 4 are shown in the following table.

【table】

[Table] As explained above, the solid resol resin of the present invention has significantly superior heat resistance, moisture resistance, and especially electrical insulation properties compared to novolac resins that represent conventional phenolic resins, and also has its own properties. By combining the mechanical strength when heated, it has physical properties comparable to other thermosetting resins, making it a resin that can be expected to be widely used in fields that have not been considered before. Furthermore, the solid resol resin of the present invention can be suitably used not only as a molding material but also as a binder for shell mode laminates, paints, adhesives, and the like.

Claims (1)

[Claims] 1 phenols and 1 mole of the phenol
~2 moles of aldehyde and the weight of phenols
In the presence of 0.1-2% by weight of salts of divalent metals, 2-
Heat condensation reaction for 6 hours, then at a temperature of 110-120℃
and a free phenol content of 2% by weight or less, which consists of dehydration at a reduced pressure of 700 mmHg or more,
A solid resol resin having a gel time of 180 to 480 seconds, and when made into a molding material by adding 65.5 parts by weight of crystalline silica, 3 parts by weight of magnesium oxide, and 1.5 parts by weight of zinc stearate to 30 parts by weight of this resin, the normal state , boiling volume specific resistance value 10 ¹⁴ Ω or more,
Volume resistivity at high temperatures of ^10-11 Ω or higher at a temperature of 180°C, volume resistivity at high temperatures and humidity of ^10-11 Ω or higher after 1000 hours at a temperature of 120°C and a relative humidity of 100%, and a temperature of 120°C and a relative humidity of 100%. 1. A method for producing a non-ammonia benzyl ether type solid resol resin, which exhibits physical properties of a water absorption rate of 1.0% or less after 1000 hours.