DE2037930A1 - Process for the continuous Her provide a phenolic foam - Google Patents

Description

HANSRUSCHiCE ^{β £ /} 30th JuH

P. 1368

Sumitomo Bakelite Company Limited, Tokyo, Japan

Method for continuously producing a

Phenolic substance

A method for continuously producing a phenolic foam comprises mixing a phenolic hovolak with a melting point of 45 to 85 ⁰ C, measured by means of a capillary method, a foaming agent, a hardening agent which can form methylene bonds when heated, and a surfactant to the foam cells to make small, extruding the resulting mixture with the aid of a screw-type extruder at a temperature of the molten mixture in the extruder from 6o to 11O ⁰ C, introducing the resulting foamable extrudate without cooling into a cavity, which

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by guide walls "is limited, and heating the Extrudates for simultaneous foaming and curing.

The invention "relates to a method for continuous Manufacture of a foam by using a phenol novolak.

A conventional method is known which comprises mixing a resin, a foaming agent which generates a gas when heated, such as dinitrosopentamethylene tetramine and benzenesulfonylhydrazide, a hardening agent which can generate methylene residue when heated, such as hexamethylene tetramine, and a surfactant ^r % i ^; e ^C; ^ n sorbitan alkyl ester, which comprises placing the resulting mixture in a mold and then placing the mold between hot plates or in a heating oven and heating to foam and cure the mixture.

For a method of obtaining a foamable composition by mixing a resin and of various additives, the following three are basically known.

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The first method involves rapid clogging a curing agent, a foaming agent and a surface active agent to form a resin, which is previously heated and melted, and then mixed with stirring.

The second is a method in which a foaming agent and other agents are mixed with the resin Can be mixed and kneaded with the help of a heated two-roll mixer.

The third is a process in which the resin, a foaming agent and other agents in powdered State to be mixed.

The methods described above, however, have various disadvantages. In the first procedure the foaming agent and the hardening agent are easily decomposed when mixing is necessary at about 12o C to allow the hardening agent and the like is sufficiently mixed with the resin even when a resin is mixed with a Melting point of 45 ° C is used, measured using a capillary method. Therefore

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a working like temperature control or fast Very difficult to stir. Or remodeling will be very bad because of the different in the Dissolution of the curing agent and the foaming agent in the batches so that it is difficult to make a composition which contains the components in the desired proportions and which the Has desired foamability. The second Procedure it is very difficult to mix one mass at the same time; when the batch quantity per unit of time increases, the heat due to shearing increases, increasing the temperature of the Mixture is increased so that both the foaming agent a-Is and the curing agent are decomposed, whereby the foamability is reduced. In addition, this temperature rise is largely due to the Rolling time influences, so that it is also difficult to obtain a composition which Contains the components in the desired ratio and has the desired foamability. The third method is because all materials are powdered as finely as possible must and must be mixed in order to make the cells of the foam even and small, the bulk density will be low, it will take a lot of work, and the effectiveness of the process

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with the following stages it is extremely reduced.

As can be understood from the foregoing description, the above methods are relative Work and better use of heat inadequate because of the foamable composition is only obtained with the help of a batch process and is then foamed. This is not economical. Furthermore, it is difficult to obtain a homogeneous composition and to make a good quality article from it because of the mixing and kneading is insufficient in each batch. In addition, the quality varies between batches. Since the foamable composition is placed in a mold at room temperature andj ^ then When heated, it is very difficult to get the whole composition evenly at the same time to heat, which results in uneven foaming. This phenomenon can in particular can be seen in a foam of high apparent density, with an increased Amount of foamable composition is required for a batch or you can see it when a very thick foam is obtained

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shall be. It is also disadvantageous because of the density of the foam and the orientation the bubbles in the foam become uneven, the foaming being so disordered that that lines and grooves can appear on the surface of the foam, it is in the lall of a novolak foam, it is impossible to use the same process for continuous manufacture a thicker foam and for cutting in a required thickness by using liquid materials in a urethane foam or a phenolic resole foam (US Pat. 3,214,793)

On the other hand, one of the conventional mixing and kneading processes is known to be a Extruder.As a kneader in the production of phenolic molding materials there "it can be used to make the molding material with a pulp to mix and knead. However, if a thermosetting resin composition without any Used with filler or with a bit of garbage becomes, the resin becomes sticky and adheres around a screw, and hardening of the resin occurs because of the frictional heat * which at

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Mixing and kneading is left free. Because of this, the composition may not be sufficient be mixed and kneaded. A thermoplastic foam is generally one Extrusion press is used because the resin is thermoplastic and curing by heat is not

to be observed ", and that unequal to M

a thermosetting resin which has a limitation in heating, mixing and kneading in a cylinder of an extruder. However, when the resin is thermosetting, the method used for a thermoplastic resin has not been possible because of the above-mentioned property of the resin. It has now been found that the desired phenolic foam can be continuously produced by using a low melting point novolak and extruding under certain specified conditions. In this way, the highly homogeneous extrudate obtained "M, and this extrudate can be directly in the desired thickness of a" thin foam until a thick foam, especially a foamed be very thick.

One object of the invention relates to the continuous Making a very uniform

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Foam of the desired thickness, especially a very thick foam.

Another object of the invention is the continuous production of a foam with a clothing material using a phenolic novolak.

The present invention comprises mixing a novolak having a melting point of 45 "to 85 C as measured by a capillary method, a foaming agent which generates a gas when heated, a hardening agent which forms methylene bumps when heated, and a surface active agent, extruding the resultant Mixing with the aid of an extruder in which a screw is kept cold, namely at a temperature of the molten mixture in the extruder from 6o to 110 ⁰ O, introduction of the resulting foamable extrudate without cooling into a horizontally extending cavity, which is from at least two conveying walls is limited and open at both ends in the pressing direction, and heating the extrusion at the same speed as that of the extrusion from the inlet end to the outlet end in order to

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simultaneous foaming and hardening, and continuous hardening of the foam obtained in this way from the outlet end.

The phenolic hovolak used in the present invention is made by reacting formaldehyde and a phenolic or phenol such as phenol or gresol in the presence of an acidic catalyst. The phenolic uovolak has a melting point of 45-85 ⁰ O, measured with the aid of a capillary method, and is in the form of particles which pass through a two-mesh sieve; the melting point described here has been measured by a capillary method in accordance with JIS K 8oo4 (ASTM E 324-67 T). · ■ ■

As a foaming agent, which is a gas when heated produced, is azobiaisobutyronitrile, dinitrosopentamethylenetetramine, Benzenesulfonylhydrazine, sodium bicarbonate and i-sodium carbonate are used. Typical hardening agents that form methylene bridges when heated are hexamethylenetetramine and paraforraaldehyde-polyoxymethylene and the like may also have been used «As

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H -4-

- 1o -

Surfactants are Sorbitanalky lester, Polyoxymethylene nonylphenqläther, height te aliphatic amine acetates of the general Formula,

R-BH ₂ * CH ₅ - COOH,

where R is a saturated or an unsaturated aliphatic radical with eight or more carbon atoms iat, polyoxyethylene polyoxypropylene block copolymers the general formula,

HO --- 4- C ₂ H ₄ O -> - (- C ₃ H ₆ O -> - ₅ -4 C ₂ H ₄ O -} --- H,

where e and η are positive integers and m is greater than 2o and where an ethylene oxide content of less than 2o $> of the average liöleoular is present, condensation products of ethylene diamine with polyoxyethylene, polyoxypropylene and block polymers of the general formula,

H -fo ^ O ^ -f- C ₃ H ₆ O)

N-CH ₀ -

where χ and y are positive integers and that Molecular weight greater than 2,000 are silane-cyclool copolymers the general formula

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Si-O-R-O -f ----

may be used, where E is an alkylene or polyoxyalkylene radical, R ^{1 is} an alkyl radical having Ibis carbon atoms and can have a value of 2-1o, preferably 3 "to 5. Adding a lubricant to reduce the frictional heat during mixing and kneading can be better The lubricants can be higher aliphatic acids such as stearic acid, metal soaps such as calcium stearate and barium stearate or waxes. In addition, to improve the quality of the foam, for example rubber , polyvinyl alcohol or polyethylene glycol to give elasticity, flexibility and plastic deformability, a small amount of one can be used Fillers such as wood flour, calcium carbonate and talc for better hardness, various fiber materials, a fire retardant and a plasticizer can be added.

As an extruder, any type can be used in this invention. However, in order to prevent

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so that a molten resin on the screw adheres or to avoid a local temperature rise, it is necessary to use an extruder to use in which cold water circulates inside the screw, preferably a Distance of 0.3 to 0.05 tnto between the snail and the barrel is present and wherein the compression ratio of the screw is greater than ^ and enable rapid extrusion; such an extruder prevents the generated gas enters and the residence time of the extrudate decreases.

A good result can be obtained if a screw with fast compression is used, which results in less heat in the feed zone. For the purpose of the desired operating conditions of the extruder, the temperature drop between the drum temperature under a hopper and those of the over area of the extruder is set so dr.ß former is at least 4o ° C higher than the latter. This is a very important condition regarding the melting point of the ITovolak used.

If the melting point is lower than 45 ⁰ O,

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the powder is easily compacted and solidified into a mass, and the mixture cannot be fed into the extruder in a constant amount, so that continuous operation is impossible. If it is higher than 85 ⁰ C, the extrusion must be carried out at such a high temperature by a foaming and curing to cause ·. It is therefore not possible to extrude the mixture using an extruder. If so, the novolak having a melting point of 45-85 ⁰ C with other materials at a temperature of the extrudate from 6o - is extruded 11o C, while the screw is cooled, it is possible to effect a continuous and adequate mixing without foaming and With this process, the foamable composition thus obtained has a very high quality. However, if the extrusion temperature drops below 60 ° C, sufficient melting and mixing becomes impossible. If it is higher increases to a temperature as 11O ⁰ C, a foaming and curing is done quickly, so that this is not vorteilig.

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When pressing is carried out under these conditions, it is desirable to set the drum temperature to 50 τ 100 ° C before inputting the raw material and then start ghargieisi at a screw rotation of 10 to 90 rpm or so. When the extrudate begins to exit the die, the heating of the drum is stopped and the material is melted and adiabatically mixed and kneaded by the frictional heat only, keeping the heat balance. A good result can be achieved with these methods. As the heat transfer medium is set to an appropriate temperature, can flow around the cylinder, in order to keep the temperature uniform despite changes in outside temperature, mixing and kneading ^K can be performed while the required temperature is maintained "In this way, also a good result can be obtained.

Uun becomes foamable in the extrusion press mixed extrudate extruded through a nozzle into various shapes such as sheets, rods and tubes, which without cooling in foils

BATH ORIGINAL

In the case of a film, the thickness is adjusted with the help of rollers which are connected to the nozzle, in the case of rods they are rolled by rollers, or in the case of tubes they are cut into films. The temperature of the
Rolling can be controlled from room temperature to 90 ° C. At this time, the temperature of the nozzle is desirably 60 to 90 ° C
to prevent foaming of the foils. In addition, it is possible to 'the final
Thickness of the required foam can be controlled by adjusting the thickness of the orifice. The debris weight can be increased or decreased appropriately by increasing or decreasing the amount of the
Foaming agent can be controlled. The cavity
is heated sufficiently beforehand to foam and harden the foamable extrudate. Preferably the temperature of the inlet end is higher than that of the outlet end in order to prevent the foamed part from corrugating and rolling back to the unfoamed part. Since the upper part of the foamable sheet is heated by a space from the top wall and the sheet is in direct contact with the bottom wall
there is preferably - between the top wall and the bottom wall of the cavity a speed lower

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BATH ORIGINAL

It was decided that the upper temperature was higher than the floor temperature. On this one In this way, the film can be heated evenly. With regard to the formation of the cavity there are different procedures. In one example it is bounded by two endless bands, which is a pair of horizontal, parallel spaced apart walls create. In another example, it is made up of four endless ribbons, one blanket, one Bottom and two vertical side walls or by an endless belt, the top wall and bounded by a U-shaped caterpillar.

Various methods of heating can be considered for example a heater on the back of the belts can be provided so that the entire cavity can be in a heating furnace.

According to the invention it follows that the Kextrudat directly is introduced into the cavity without cooling that aas extrudate, which on a constant uniform temperature is maintained, the slightly lower when the skin temperature is,

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is heated evenly. So it is understandable that the heating time for foaming and hardships can be cut considerably that even heating becomes possible, whereby a uniform foam can be obtained, even if it is very thick.

The present invention is as follows explained in more detail with reference to the accompanying drawings;

In the drawings show:

Pig. 1 is a diagram showing the relationship between the debris weight and the maximum The thickness of a foam sseigt in which Dioke a uniform foam can be produced (the term "non-sticky foam" means that the foam has no defects in appearance, and if the foam cut is't is the soot weight of * each * cut rope within + 2o # of the average value),

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if, according to the invention and in a conventional case, the foamable powdery composition is foamed in a mold ₉

Fig. 2 shows an example of a device for Manufacture of a foam according to the invention,

Pig. 3 is a diagram showing the relationship between the debris weight and. the number of from the surface of foams cut parts made with present and a conventional process can be obtained.

As shown in Fig. 1, with the method according to invention j represented by the ICrve 1, a significantly thicker foam than with a traditional method, which is represented by ii © curve © 2 »Da © e. aSglioh igt. _s to obtain with &<& w Yerfaferan g © raäis invention Tersofeäuiabare ZusatB® @ Breakfast © tsuag teontinuierlioh, di © s®s © rfidnungsgsfalsse process is very farmer © ha, ftlioh ₉ and it can be a © horaioge-τα® SiaeaiBHQiisetzungs, walsh © di © gswünsohte Vor · =

having foamability can be constantly obtained. In addition, she has a very excellent Property of being a foamable composition even if the pressing process is interrupted can be obtained with the desired quality.

According to the invention, a foam with any desired thickness from thin to thick and with a skin can be obtained on both surfaces. Furthermore, a foam board can be made with any desired Thickness can be obtained by cutting a thicker foam. The cut one Foam is uniform from the surface to the inside and does not have any hardness Skin on. Therefore, there is no such problem if a layered material is applied to the foam ciifget'-agen is due, like the adhesion shortening that used in the foaming stage Mold release agent. Furthermore, this foam can be used as a desirable base for gluing by pressing a relatively low surface edge coating material such as aluminum. Another The advantage is that it is uniformly frothed thick material into parts of any thickness

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- 2ο

and any shape can be cut - like this one described above is »If a coating material inserted continuously along the inside of the top and bottom walls of the cavity xfirdj while a foamable material is entered into the cavity while the coating material and the resulting Combine show material with each other by the pressure, which results from the filling of the cavity with the foamed material results, thereby obtaining a plate continuously can be, which has the coating material. An example of the invention will be 'described with reference to the drawings, the parts are units of weight when not mentioned otherwise.,

Hundred parts of a phenolic novolak that have passed through a two-mesh sieve, 12.5 parts of hexamethylene tetramine, 5 parts of dinitrosopentamethylene tetramine, one part of sorbitan monolaurate and 0.5 parts of stearic acid were mixed using a mortar mixer The mixture obtained in this way was then poured into a hopper 1 of the extruder of a Yorrich-

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tung given in Pig. 2 is shown. The barrel of the extruder was heated to about 90 ° C from the compression zone to the die, the drum temperature under the hopper was adjusted to about 40 ° C by water cooling, and the screw was cooled after the mixture was added. When the extrudate emerged from the die, heating was stopped. As a result, the temperature between 8o ° 0 to 110 ⁰ C was from the compression zone to the die maintained by an inner frictional heat to permit a continuous mixing and the 'mixture was extruded in the form of a film having a thickness of from about 1o mm from the T-die attached to the head of the extruder. This film 5 was cut by a pair of rollers 4 to make the thickness constant, and then placed on the endless belt 5 and conveyed into the heating furnace 8, where the cavity 9 was formed by four endless belts which formed the bottom wall 5, the top wall 6 and the two vertical side walls 7 form, the film being foamed and kneaded in this cavity. In this cavity, the show fabric was 1o con-

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continuously produced. The furnace 8 was kept at 150 ° 0
and 1000 mm "wide.

Maintained 15o ° 0, and the cavity was 300 mm high

The foam obtained in this way had smooth surfaces and a cross section of 3,000 mm 1,000 mm and was uniform. In Pig. 5 is the result The measurement of the debris weight of each layer is shown to be 3omm in thickness from the top the foam was cut off. It can be seen from curve 1 in Mg. 3 that each layer has substantially the same bulk weight and an extremely uniform foam can can be obtained. For comparison, the same materials were mixed, rolled and pulverized, and the powdered composition was foamed in a shape having a cross section of 300 mm 100 mm had »As from curve 2 · As can be seen in FIG. 3, the debris weights of the layers are those of the one thus obtained Foam was cut off, not evenly, so that the foam was not usable for an article.

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Claims (1)

fii Expectations 1.) Process for the continuous production of a foam, characterized in that that a novolak has a melting point of 45 ⁰ C "to Ö5 ° C, measured with the aid of a capillary method, a foaming agent which generates a gas when heated, a hardening agent which forms methylene bridges when heated, and a surface-active agent are mixed so that the resulting mixture is mixed with the aid of an extruder is extruded, in which a screw is kept cooled at a temperature of the molten material in the extruder from 60 to 110 ⁰ C, that the resulting foamable extrudate is introduced without cooling into a horizontally extending cavity which is delimited by at least two J guide walls and is opened at both ends in the extruding direction, that the extrudate is heated while it is conveyed from the inlet end to the outlet end at the same speed as the pressing speed to simultaneously foaming and curing, and that the foam thus obtained is continuously discharged from the outlet end Will get removed. 109808/2098 2.) A process according to claim 1, characterized in that the foaming agent is ₀ Dinitroscpntamethylentetrarain 3e) Method according to claim T ₅ , characterized in that the curing agent is hexamethylenetetramine ο 4.) The method according to claim 1, characterized in that the surface-active agent by the formula R - HS _2. ° CH ₃ - COOH where S is a radical _{9 selected} from the group consisting of saturated and unsaturated aliphatic radicals with eight or more carbon atoms " 5 °) Method according to claim 1, characterized in that the surface-active agent is a Polyoxyethylene polyoxypropylene block copolymer the formula HO -f- C ₂ H ₄ O - ^ - JI C ₃ H ₆ O - * - {- C ₂ H ₄ O -4 ~ - H ₆ O - * - {- C ₂ H ₄ O -4 ~ 2037S39 " where e and η are positive integers and τη is greater than 2o, the content of ethylene oxide being more than 2 ο % of the average molecular weight. 6.) The method according to claim 1, characterized in that that the surfactant is a condensation product of a polyoxyethylene-polyoxypropylene - Block copolymer with ethylenediamine, which is of the formula η -4- C ₂ H ₄ O -4-yf H -4- O ₂ H ₄ O -} --- f -CH ₂ -CH ₂ -F is shown, where χ and y are positive integers and the molecular weight is greater than 2ooo is. 7.) The method according to claim 1, characterized in that that the surfactant is a silane glycol copolymer of the formula Si. - 0 - R * 0 where R is a radical that is outside the group 109800 / 2QSt miQlNAL JNSPECTO is selected, which consists of alkylene and polyoxyalkylene radicals, E ¹ is an alkyl radical having 1 to carbon atoms and η is 2 to 1o on the average. 8.) The method according to claim 1, characterized in that 'the extruder of the type faster Is compression and has a compression ratio greater than 2.4. 9.) The method according to claim 1 _s, characterized in that the upper wall of the cavity is heated to a temperature which is higher than that of the bottom wall. 1ο.) Method according to claim 1 _9, characterized in that the cavity is heated to a temperature which is greater than that of the inlet. 11t) Method according to claim 1 _5, characterized in that a lubricant is added to the mixture. ORiGiNALiNSPECTED 12.) Method according spoke 11, characterized in that that the lubricant is a stearic acid. 109808/2098 i ^{a <?}