DE1520407B2 - Production of laminates - Google Patents

Description

1 2

The invention relates to the use of an electro- The heat treatment of phenols with formaldehyde

Low-lytic aqueous emulsion, which contains a hot hyd in excess using basic

curable condensation product from a hydroxy catalyst with subsequent coagulation of the

benzene compound and formaldehyde contains, as formed and separated resin by the addition of

Impregnating resin for the production of laminates, 5 boric acid is already known. Because this teaching is

such as hard paper and the like, by impregnating fiber, but for the production of phenolic resins in general

material. it does not indicate that an electrolyte

Using such an impregnating resin, poor aqueous emulsion, which hardens a heat

impregnated paper webs are suitable for a carrier condensation product of a hydroxybene

material for printed circuits and wiring contains io zol compound and formaldehyde, then as

to be processed. Impregnating resin for the production of laminates

A carrier material intended for this application can be used if it contains a low molecular weight material which must meet high electrical requirements, an enthydrophilic condensation product from which it speaks. It is desirable that the dissipation factor, tg δ, not settle any resin particles, and when the hydrodynamic dielectric constant and the conductivity of the condensed material after formation of the condensation product are minimal. is reduced.

The electrical properties of the carrier material in the investigations carried out on the present hang to a large extent from the physical and discovery, it was found that chemical properties of the impregnation that it used to achieve a well impregnating impregnation Impregnating resin is necessary for a given fiber resin, the reaction between the material off. Hydroxybenzene compound and the formaldehyde in

In this context, the electrodes are above all pH values between 7.0 and 8.5

trolyte content and the impregnation ability of the impregnation. An increase in the pH value above 1 "\

resin as well as the required hardening tempera- 8.5 has changed with regard to the final electrical Λ

door and time of the resin after impregnation of the fiber lyt content of the hard paper proved to be unfavorable,

materials matter. because undesirably large amounts of alkaline react

It is particularly necessary that the electrode material is necessary in order to keep the lyt content of the impregnating resin as low as possible in this area. To increase the pH value by one unit while fulfilling this requirement, a pH value lower than 7.0 has the consequence that they propose to prepare an impregnating resin from a 3 ° less suitable high molecular weight aqueous solution Emulsion of a phenol or cresol form, reaction products are formed. There was an aldehyde reaction product, which was also found to further reduce the use of a percentage of high molecular weight products built into the resin molecule by a basic substance such as ammonia or an amine suitable for using an excess of formaldehyde. The aim is pH 35. However, a reaction mixture of this type falling between 1.5 and 3.0 mols due to the amount of formaldehyde has proven to be particularly suitable in this combination of incorporation of the catalyst and due to the formation of the slope. With regard to reaction products with formaldehyde, the desired hydrophilicity of the impregnating resin quickly decreases, which means that there is a risk that too many high-molecular-weight reaction products are created to achieve an extended three-dimensional molecular weight reaction product. It is therefore necessary, in practice, to continue the reaction until at least basic substances are used and the reaction takes 1.2 mol of formaldehyde per mol of hydroxybenzene after a few Minutes are found by cooling the bond. Finally, the surprise-boiling mixture was largely delayed. The found in such a way that the pot life of the impregnating resin reaction is difficult to reproduce, 45 despite the acidification to between 2.5 and 5.0 and the impregnating resin obtained has only a short pot-lying pH value remains favorable,
time on. These measures do not completely prevent the formation of high molecular weight products in order to establish the desired basicity in the reaction, so that a strongly basic reaction can be produced in the mixture so that the impregnability is unsatisfactory. use the substance that is not included in the reaction

The invention is based on the object, layer 5 ° is installed and soluble in the reaction mixture

is molding materials with improved electrical properties. In terms of the desired electrical

to accomplish. Properties of the end product are substances such as

According to the invention, this object is thereby preferred alkaline earth metal hydroxides and tertiary amines,

solves that for impregnation a low-electrolyte aqueous As an acidic reacting substance in the resin molecule

rige emulsion is used, which is incorporated in the manner and that with that in the reaction mixture

it has been suggested that a hydroxybenzene or some basic reacting substance is present a little

Mixing hydroxybenzene compounds in water with dissociated or insoluble salt forms can, for. B.

an approximately molar excess of formaldehyde and acids such as boric acid, m-cresotinic acid and others

such an amount of a basic reacting substance, phenol carboxylic acids, aminocarboxylic acids, aminosul-

that the pH of the mixture between 7.0 and 8.5 60 fatty acids and the like are used,

is, heated until at least about 1.2 mol. It was also found that the impregnability

Formaldehyde are bound per mole of hydroxybenzene, the liquid is influenced by the amount of water

and then the reaction mixture to a pH value that, based on the originally in the reaction

between 2.5 and 5 hydroxybenzene present in the impregnating resin with the help of an acidic mixture

The substance that is present in the resin molecule is acidified. Maximum results are achieved

is built and the with the in the liquid before - if this amount 20 to 40 ml per mole of hydroxybene

the existing basic reacting substance is a little dissozol,

forms a salt or an insoluble salt. These values can be achieved if a part

of the water is distilled off after the resin preparation or only the desired one at the beginning of the reaction Amount of water is used. The required amount of formaldehyde is then partly in the form of Paraformaldehyde added.

If a large excess of formaldehyde is used in the manufacture of the impregnating resins, it is advantageous to wash the impregnating resin once or several times with water after production reduce the level of free formaldehyde. In such cases, this measure creates a more homogeneous impregnation of the fiber material possible. The impregnating resin can optionally also other substances, such as surface-active substances, dyes and the like, can be added.

The advantages achieved by the invention are in particular that without special measures, like repeated soaking and intermittent drying, hard paper with resin contents of about 200 percent by weight, calculated on the weight of the paper, produced by soaking the fiber material once can be. With the aid of the impregnating resin mentioned above, this content is under the same conditions about 100%. Because of the favorable pot life of the impregnating resin, it is possible to use the impregnated To harden the material faster and / or at a lower temperature, which saves further time and energy and a less detrimental effect on the often temperature-sensitive filler (e.g. Paper) means. In addition, both the mechanical and electrical properties of the through-hardened material compared to that impregnated with the basic impregnating resin and then hardened through Material improved.

The invention is explained in more detail with reference to the following examples.

Manufacture of the impregnating resins

Example I.

Impregnating resin A was obtained by using a mixture of

734 g phenol solution (approx

11 percent by weight water) (7 mol)

845 g about 37% formalin (10.5 moles)

10.5 g triethylamine (0.105 mol)

29.9 g stearylamide (0.105MoI)

its pH value, in a known manner with a glass electrode measured, was 8.30, heated to boiling point in about 25 minutes with stirring and then Was boiled for 65 minutes, whereupon 1.25 moles of formaldehyde were bound per mole of phenol. at 400 ml of liquid were then distilled off under reduced pressure. Then 7.8 g of boric acid were added to the reaction mixture with stirring cooled down. The pH of the mixture was now 2.95 and it contained about 30 ml per mole of phenol Water.

The emulsion obtained could be used as an impregnating resin without further treatment.

Example II

Impregnating resin B was obtained by using a mixture of
5240 g phenol solution (approx

10 percent by weight water) (50 mol)

1530 g technical paraformaldehyde (25 mol)

2013 g of about 37 ° / _o formalin (25 moles)

50 g triethylamine (0.5 mol)

213.5 g stearylamide .. '(0.75MoI)

whose pH was 8.00, heated to the boiling point in about 25 minutes with stirring and then Was boiled for 100 minutes, whereupon 1.28 moles of formaldehyde were bound per mole of phenol. Afterward 37.1 g of boric acid was added to the mixture, causing the pH to drop to 3.3.

The impregnating resin contained about 35 ml of water per mole of phenol originally present.

20th

Example III

Impregnating resin C was obtained by using a mixture of

540.5 g cresol (40 to 45% meta-,

55 to 60% para-) .. (5MoI)

735 g about 37% formalin .. (9 mol)

0.37 g Ca (OH) ₂ (0.005MoI)

20 g cetyl alcohol (0.083MoI)

whose pH was about 7.5, heated to the boiling point in about 20 minutes and then boiled for a further 260 minutes, 0.37 g of Ca (OH) _{2 being} added after 20 minutes to bring the pH to about 7.5 to hold. After cooling, the mixture was acidified to pH 4.6 with m-cresotinic acid, which required about 3 g of the acid

was.

300 ml of distillate were then distilled off at reduced pressure and a temperature of about 70 ^{° C.} To the residue were added from 7O ⁰ C and stirred for 15 minutes 400 ml of water. After cooling, 450 ml of the aqueous top layer were removed and the remainder emulsified. The impregnating resin then contained about 22 ml of water per mole of cresol originally present.

B e i s ρ i e 1 IV j

Impregnating resin D was obtained by using a mixture of

200 g 94% phenol solution (2MoI)

323 g about 37% formalin .. (4 mol),

0.44 g Ca (OH) ₂ (about 0.006 mol)

8.0 g of cetyl alcohol (0.033 mol)

55 was heated to boiling point in about 25 minutes and then boiled for 2 hours. The pH was 8.2. 120 ml of distillate were then distilled off, about 0.7 g of boric acid were added and a further 60 ml of distillate were distilled off at reduced pressure (about 100 mm Hg). 100 ml of water were added to the residue, followed by cooling with stirring. After the phase separation, 120 ml of the aqueous top layer were removed and the remainder was emulsified by stirring. The pH of the impregnating resin was 4.5, and about 20 ml of water were now present per original mole of phenol.

Application of the impregnating resins

Table I.

The impregnating resins A and B are particularly suitable for the production of hard paper with a high resin content (50 to 67%, calculated on the total weight, that is 100 to 200%, calculated on the paper weight); The impregnating resins C and D are particularly suitable for hard paper with a moderate resin content (approx. 50%) suitable.

The hard paper types in the examples given below were produced in the usual way, ie paper webs are impregnated with the impregnating resin at room temperature and these are then dried in a tunnel oven at a temperature of about 160 ^° C., with a certain degree of hardening occurring. The temperature and the dwell time in the furnace are controlled in such a way that the impregnated material has a degree of flow suitable for pressing when it leaves the furnace. In all cases, Kraft paper was used as the "filler" and sheets nearly 1.5 mm thick were pressed by stacking 10 to 12 sheets on top of one another. The compression pressure used was 60 kg / cm ² in all cases, but other, preferably higher, pressures are also very suitable.

ExampleV

Phenol-formaldehyde resin laminated paper

Hard paper based on impregnating resin A and Kraft paper.

A ₁ . Pressing time 15 minutes, pressing temperature 145 ° C,
Resin content 64.1% (179%, calculated on paper).

A ₂ . Pressing time 15 minutes, pressing temperature 16O ⁰ C,
Resin content 64.4% (181%, calculated on paper).

Acetone extraction numbers show that the two types are almost completely cured.

Measuring frequency tg <5-
A ₁ 10 <b at 22 ⁰ C
A ₂ 60 Hz 71 > 800 10 ² Hz 97 > 800 10 ³ Hz 139 400 2-10 ³ Hz 145 329 5 x 10 ⁴ Hz 220 269 3-10 ⁵ Hz 275 318 10 ⁶ Hz 317 361 2 x 10 ^e Hz 347 - 3 x 10 ⁶ Hz 374 398

35 Dielectric losses (tg <5) were measured after a relative humidity of 65% for one week. It follows from this that it is advantageous from an electrical point of view to use low pressing temperatures to be able to.

Example VI

Phenol-formaldehyde resin laminated paper

Hard paper based on impregnation resin B and kraft paper.
B ₁ . Pressing time 20 minutes, pressing temperature 145 ⁰ C,

Resin content 60.7%.
B ₂ . Pressing time 20 minutes, pressing temperature 160 ⁰ C,

Resin content 61.1%.
B ₃ .:. Pressing time 20 minutes, pressing temperature 145 ⁰ C,

Resin content 52.2%.
.B ₄ . Press time 20 minutes, press temperature 160 ° C, resin content 52.2%.

In all cases the plates obtained were almost completely cured (extraction tests). Some mechanical and other properties depending on the pressing temperature result from table below.

Table II

properties

B ₂ B ₃ B ₁ 1325 1775 1600 1200 1675 1450 6.50 10.5 9.15 5.15 8.05 7.35 1075 1350 1325 925 1275 1175 5.43 5.02 5.46 19th 21 18th

X *)

Flexural strength (length)

kg / cm ² (width)

Impact strength (length)

kg cm / cm ² (width)

Tensile strength (length)

kg / cm ² (width)

Dielectric constant ε at 1V ₂ MHz at 20 °
Breakdown voltage kV / mm at 20 ^° C

1550

1425 7.15 6.35

1250

1000 4.87 26 1100 1000 5.5 5

900 850 5.5

*) These values are included for comparison. The pressing temperature was 160 ° C., the resin content 50 to 55%. The impregnating resin was achieved by cresol with formaldehyde in a ratio of 1: 1.15 under the influence of 0.1 mol of ammonia allowed to react in water at boiling temperature for about 10 minutes.

Table III Example VII

60

Cresol-formaldehyde resin hard paper

Hard paper based on the impregnating resin C and Kraft paper. Pressing time 15 minutes, pressing temperature 16O ⁰ C, resin content 48.5%. Dielectric properties, measured after a relative humidity of 65% for 1 week at room temperature, according to Table III.

65

Hard paper type C ₁ C * "> Data at 20 ° C V ^ ₂ ) tg <5-10 ⁴ and: 148 50Hz 139 > 550 100 Hz 138 445 800 Hz 149 226 1,800 Hz 183 200 30,000 Hz 234 216 300,000 Hz 293 257 1.5 MHz 430

Claims (1)

Table III continued Specific volume resistance
in ohms / cm 6.8 · 10 ¹⁴ *) See footnote in Example VI. 2.6 · 10 ¹² Dielectric constant ε at Claim: 50Hz 4.8 - 800 Hz 6.0 1.5 MHz 4.4 5.3 IO Use of a low-electrolyte aqueous emulsion which has been prepared in the manner that a hydroxybenzene or a mixture of hydroxybenzene compounds in water with a about a molar excess of formaldehyde and such an amount of a basic reacting Substance that the pH of the mixture is between 7.0 and 8.5 is heated until at least about 1.2 moles of formaldehyde per mole of hydroxybenzene are bound, and then the reaction mixture to a pH between 2.5 and 5 with With the help of an acidic substance that is built into the resin molecule and is acidified which is a little dissociated or a little dissociated with the basic reacting substance present in the liquid Insoluble salt forms as an impregnating resin for the production of laminates such as hard paper and the like, by impregnating fiber material. 009 548/309