DE2158511A1 - Process for molding thermosetting resins - Google Patents

Description

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DR. E. WIEGAND DIPL-ING. W. NIEAAANN DR. M. KÖHLER DIPL-ING. C. GERNHARDT 2158511 MONKS HAMBUKG TELEPHONE, 555Οί 8000 MONKS 15, TElEOiAMME. KARPATENT NUSSBAUMSTRASSE 10

25 November 1971

W 40 859/71 - Ko / DE

Mitsubishi Petrochemical Co. Ltd., Tokyo / Japan

A process for forming thermally curable resins

The invention relates to a method for molding thermosetting resins.

According to the thermosetting resin molding method of the present invention, a filler is previously placed in a mold, and then the filler is impregnated with a thermosetting resin, whereupon the resin is solidified.

The invention relates to a method of molding a thermosetting resin by incorporation a filler in a mold and subsequent impregnation of the filler with a thermally curable one Resin.

By curing a mixture of a light weight filler such as one of Glass-made filler, and an unsaturated polyenterhera or epoxy resin made product often as a small material or as artificial wood

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or used to manufacture such products, usually employing a process where molding a mixture of the filler and a liquid thermosetting resin in a mold. In these conventional methods, however, it is difficult to increase the proportion of the filler widely and continue to do so the filler is not uniformly dispersed in the liquid thermosetting resin.

If fine hollow materials continue to be fillers are used, the problem arises that shear stress on the fine hollow materials id lien is applied in mixing the liquid thermosetting resin and the fine hollow materials so that a part of the fine hollow materials is damaged, so that the low density properties of the fine Hollow materials are reduced.

According to the method according to the invention, a large proportion of a filler can be mixed into the product and the filler can also be uniformly dispersed in the product since the filler is previously is introduced into a mold. Sa furthermore the liquid resin to be poured into the mold does not contain any fillers, the flowability of the resin according to the invention is not reduced. Even if fine hollow materials are used as fillers according to the invention, they are not damaged and therefore the properties the low density of the fine hollow materials is very effectively maintained and exploited.

As thermally curable resins, resins can be used, for example, in the context of the invention, the one Resulting crosslinking when heated, for example unsaturated polyester resins, epoxy resins, phenolic resins or Polyamide resins.

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The solidifying agents or solidifying catalysts known for each of the above resins can be used and these can be removed by those skilled in the art according to the solidification rate and temperature desired. selected appropriately.

As examples of the fillers which may be used according to the invention, fibrous materials such as glass fibers and asbestos fibers and granular or pulverfönnige materials such as silica, alumina, Calciumcarbo- d carbonate, gypsum, talc, clay and zeolites mentioned. As fillers, hollow fine particles of 1 to 1000 microns in diameter made of glass by specific methods, hollow fine particles made by burning volcanic ashes, and hollow fine particles of synthetic resins such as phenolic resins can also be used.

The above fillers can be used singly or in combination according to the reinforcing purpose will.

If, according to the invention, a microporous sheet or a filter paper through which the liquid thermally hardening resin can flow while the filler cannot flow through, a microporous sheet or the molded article covered with the filter paper can be obtained. The molded article obtained in this way has a high scratch hardness of the surface and a high impact resistance, and the impact resistance of the article is, for example, if a filter paper was used, 27 to 28 kg-cm / cn "and the surface scratch hardness is about 1.8, while, if such a filter paper is not used, the impact strength 17 to 18 kg-cm / cm " ² and the obor-

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surface scratch hardness should be 0.2. You can also use Use of such a filter paper or micro. porous arch made various shapes of objects will.

Furthermore, the one used in the context of the invention carries Filter paper or the microporous sheet helps hold the filler in shape and the filler in to solidify the particular position.

It is preferred that the liquid thermosetting Resin is poured into the mold through the filter paper or the microporous sheet from outside- In this one The speed of entry of the resin can be favored if the pressure is within the case Shape is reduced by means of a vacuum pump.

All materials can be used as filter papers or microporous sheets through which the liquid thermosetting resin goes through, but the filler does not go through, e.g. filter papers, Paper bracelets, asbestos, glass filter cloths or tissues.

The accompanying drawings serve to further explain the invention, wherein

Fig. 1 is a cross section of a for the manufacture of a levels.Shaped article according to the erfindungsger the form used in accordance with the procedure,

Fif. 2 shows a cross section of a for the manufacture of a box-shaped object according to the method according to the invention used shape,

Fig. 3 shows a cross section of an embodiment of a Form where a filter paper for the production of a molded article by the method according to the invention is used,

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Pig. 4 shows a cross section of a further embodiment a mold using a filter paper to produce a molded article according to the method according to the invention and

5 shows a wire mesh for producing a filter paper which can be used according to the invention

demonstrate.

In Figs. 1 and 2 are cases of using glass hollow particles, unsaturated polyester resin and a fiberglass mat or filter paper is shown.

According to FIG. 1, a glass fiber mat 4 is first built up from a base mold 1 and a side mold 2 Shaped and then fine hollow glass particles are uniform in the entire spaces of the mat filled in by shaking the mold. A filter paper 5 is spread over the entire surface of the mat, a liquid unsaturated polyester resin is poured onto the filter paper and then the mold from the bottom of the Form evacuated by means of a pump, as indicated by an arrow, to reduce the pressure of the system, so that the mat is impregnated with the unsaturated polyester.

After completion of the impregnation, an upper cover 3 is placed on the system and while pressing the Cover in the direction of the arrow with a pressure of a few kg / cm removes the excess unsaturated polyester resin displaced and removed through an outlet 7 of the upper cover while fixing the upper cover. Afterward the system is heated to solidify the unsaturated polyester and then that way formed product removed from the mold.

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Albeit in Pig. 1 shows an example of an impregnation of the hat with the liquid resin from above, it is also possible to impregnate the hat with the resin from the side surfaces. For example, as in the embodiment according to Pig. 2 shown a. A mold composed of a bottom mold 1, an inner mold 3 and a horizontally slidable mold 2 is used with the side mold 2 attached to form the desired distance as shown by dotted lines, a filter paper 5 is placed on the inner wall of each side mold 2 and then a certain amount of the glass fiber mat 4 is put in the space between the filter paper 5 and the inner mold 8 and also on the upper surface of the inner mold 8. Then fine hollow glass particles are filled into the entire cavity of the glass fiber mat in the mold using compressed air. After the fine hollow particles have been filled into the hat in the specific henge, a filter paper 5 * is placed on the glass fiber mat and then the system is heated to the specific temperature. Then the mold is evacuated through a hole in the bottom mold 1 by means of a vacuum pump while the side molds 2 are pushed backwards to the positions shown by the solid lines. Then a liquid resin 6 containing the setting agent is poured over the surfaces of the filter papers 5 and 5 * from above and the glass fiber mat filled with the fine hollow particles is impregnated with the liquid resin. After the impregnation is finished, the side molds 2 are conveyed to the position shown by the dotted lines and a lid 3 is placed on the system and pressed, whereby the excess resin is removed from the system as in the example described in connection with FIG

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will. Then the system is used to solidify the resin heated and obtained the molded product.

According to the invention, microporous sheets, for example made of filter paper, paper pulp, asbestos sheets, glass fiber sheets, cloths, each with a non-uniform surface, can be used to increase the impregnation rate of the liquid thermosetting resin Used in the filler to form the surface of the product and further to cover the product obtained by solidification upon heating to improve dimensional accuracy.

As shown in FIG. 3, a filter paper 5 with an uneven surface is attached along the inner surface of the side mold 2 in a mold made up of a bottom mold 1, an inner mold 8 and a side mold 2. A crepe filter paper from Toyo Filter Paper Co. is shown here as an example of such a filter paper. The fine particles and, if necessary, fibrous filler 4 are filled in the space between the inner mold 8 and the side mold 2 and the space above the inner mold 8, and a filter paper 5 'is placed on the upper surface of the filler above the inner mold 8. Then a top lid 3 is attached over the filter paper 5 ¹ at a certain distance therefrom and the interior of the inner mold 8 is evacuated through a hole in the bottom mold 1 by means of a vacuum pump, while a liquid resin 6 is simultaneously formed inside between the filter paper 5 ¹ and the lid 3 Space is poured from above so that the liquid resin 6 in the filler in the mold is impregnated through the upper filter paper 5 * and the liquid resin 6 is also impregnated in the filler applied between the inner mold 8 and the side mold 2 by the between the unequal -

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moderate filter paper 5 and the side mold 2 formed Space is impregnated through the filter paper 5. Thus, in this embodiment, the liquid resin runs, downwards along the narrow between the uneven filter paper and the inner surface of the Side mold 2 formed space and then impregnated the filler introduced into the mold, whereby a easy impregnation of the filler with the liquid resin in the form is achieved, which is a large Has volume in which the liquid resin is poured only from above.

In Fig. 3 is an example of making a Product shown with an uneven filter paper surface on the outer surface, however it is as in As shown in Fig. 4, a product with an uneven filter paper on the inner surface is also possible to manufacture. That is, an uneven filter paper 5 becomes along the outer surface of an inner shape a form formed from an outer form, an inner form 8 and a cover form attached, as in Fig.4 is shown, and then, when the liquid thermosetting resin is poured through the inlet 7, the filler 4 is impregnated with the resin and then solidified, as in the case of FIG position shown with dotted lines or evacuate the mold by means of a vacuum pump.

In addition, it is in accordance with the form of execution 3 it is also possible to attach an uneven filter paper with holes along the outer surface of the inner mold To attach positions corresponding to the positions of the suction holes 9 of the inner Fons 8. In this case it is however, necessary to prevent an excessive amount of the liquid resin from entering through the filter paper a position on the circumference of the suction holes 9 is removed,

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a flat filter paper attached to the opening of the along the outer surface of the inner mold 8 to attach uneven filter paper. It is necessary, that the radius of the holes of the filter paper is greater than the sum of the radius of the suction hole 9 of the inner shape θ and 1/2 the thickness of the molded product is to the impregnation with the liquid To accelerate resin and an outflow of the unsolidified liquid resin from the suction hole 9 impede.

The above statements also apply to the application shown in FIG. 4.

It is particularly preferred, according to the invention, to use a filter paper with unevenness on both surfaces apply, but filter papers with only one uneven surface can also be used within the scope of the invention be used. In the latter case, however, the filter paper must be attached so that the uneven Surface faces the surface of the mold.

To increase the. Pouring speed of the liquid resin by falling down through the space between the filter paper and the surface of the mold in the case of using a flat filter paper with no unevenness On the surface it is necessary to make a distance between the filter paper and the form by horizontal Displacement of the shape as shown in Fig. 2, while in the case of using an uneven filter paper or a crepe filter paper is possible that to obtain the above advantages without the need to shift the shape.

If the unevenness of the filter paper used is coarser, pouring and impregnation with the Resin lighter, but it is sometimes unfavorable that

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more than the necessary amount of the resin layer remains on the surface of the molding product. Therefore 1st it is favorable if the distance between the concave part and the convex part is less than 20 mm and the Height of the uneven portion is 0.03 to 1 mm. It is also favorable if the unevenness is formed continuously over the entire surface of the filter paper.

By using such a filter paper with uneven surface or surfaces, a product is obtained with the resin-impregnated filter paper and a further covering of the resin over it. If a liquid resin, which shows a large shrinkage on solidification, is used, the unevenness s remains corresponding to those of the crepe filter paper or the uneven filter paper on the surface of the molded product due to the shrinkage of the resin on solidification, since the thickness of the layer of Resin is only varied on the surface by varying the level of unevenness. This unevenness gives the product the appearance of wood fibers. However, if one does not want such uneven surface of the product after the impregnation is completed with an ordinary thermosetting resin, a small amount of a thermally curable resin of low shrinkage continues then added to the impregnation and solidification \ around the surface of the filter paper with the To cover resin of low shrinkage so that the formation of the unevenness on the surface of the molded product can be prevented.

Examples of such thermosetting resins of low shrinkage are epoxy resins, non-shrinkable

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unsaturated polyester resins, e.g. MMD grades, Name of a polyester made by Dai-Nippon Ink and Chemicals Inc., and the like.

Generally, however, there is a limitation called "usable period ¹¹ " on molding a thermosetting resin. Bas means that when a setting agent is added to a thermosetting resin at a certain temperature, the resin solidifies after a certain period of time , and the period of time when the resin loses its flowability due to the beginning of solidification is called the usable time. The usable period of time generally becomes longer as the solidification temperature becomes lower. The point at which the resin begins to solidify can be determined by determination That is, if the viscosity of the resin rises above a certain value, deformation of the resin becomes impossible, so that a liquid thermosetting resin must be molded within the "usable period" after production.

On the other hand, since the forming period becomes shorter, in order to make the process more advantageous since the solidification proceeds more rapidly after the deformation, it will prefers to increase the solidification temperature. That is, it is more preferable to use the time by lowering the molding temperature and increasing the solidification rate by increasing it to increase the solidification temperature.

In the context of the invention it was also found that the usable period of time of the resin in molding and the solidification rate in the Solidification can be increased by mixing the solidifying agent into the resin at a low temperature the filler filled in the mold and the mold

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itself is preheated and the filler is impregnated with the mixture of resin and hardening agent. Characterized strainer begins with the prolonged period of use at a low temperature by the preheated mold equipped Harzgemiscb witit to heat the preheated filler at the same time when the resin mixture is impregnated into the filler and the temperature of the first resin impregnated is increased. By setting the setting time to the temperature to the time required to impregnate the entire resin by slightly shortening the impregnation time compared to the setting time, it is possible to start the solidification of the resin immediately after the end of the impregnation. If the temperature of the resin is increased when it is impregnated, the viscosity of the resin is also decreased, which enables uniform impregnation of the resin and a simultaneous shortening of the impregnation period. The optimum temperature to bring about the above advantages in the most favorable manner depends on the type of resin and the solidifying agent used, but since the impregnation period also depends on the strength of the molded product, the optimum impregnation temperature is most favorable by varying the temperature after determining the resin, the solidifying agent and furthermore the thickness of the product to be molded.

In the context of the invention, however, it has proven to be beneficial that the Yorerhitzungetemperatür of form and Filler is generally 30 to 200 "C higher than the tem * ptr & ture of the resin before impregnation.

It is therefore preferred that the filled-in form you fine hollow particles and Glaefasdrn and Fora previously to a higher m S6 to 20O ⁶ C

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Whenever the temperature of the resin is measured prior to impregnation, for example if the thermosetting resin is mixed with the solidifying agent at room temperature, it is preferred to first set the porra and filler in the mold to 60. to heat up to 23O ^{0 C.} Further, if the temperature of the epoxy resin to be used about 60 ⁰ C, a preheating temperature is chosen door of about 15O ⁰ C and when the temperature of a polyester resin is about 30 ⁰ C, a Torerhitzungstemperatur is selected from about 100 ⁰ C. By the above-mentioned pre-heating of shape and filler in the form of the solidification period to 20 may of -value in the case of the operation to be shortened without preheating to 30 i ".

The following examples serve to further illustrate the invention.

example 1

Thermally curable resin: unsaturated polyester, PolyIite 8007 (product of Dai-Nippon Ink and Chemicals Inc.) (viscosity 1 poise at 5CTC).

Hollow particles: particles from volcanic ash

Filler: fiberglass mat

Filter paper: Filter paper Fr. 7 from Toyo Filter Paper Co.

To 500 g of the above unsaturated polyester was 5 g of the peroxide Epomate (product of the Kawaguchi Yakuhin K.K.) was added with stirring. Two sheets of fiberglass mat were placed in the mold as shown in Fig. 1, and 100 g of fine particles from volcanic ash are poured into the entire cavity of the glass fiber mats by shaking the mold. then

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a filter paper was attached to the glass mat and the filter paper with a wire mesh. printed.

The thus solidified mold was heated to 10O ⁰ C. The unsaturated polyester mixture previously prepared was poured onto the filter paper, and the inside of the mold containing the filler was evacuated from the bottom of the mold by a vacuum pump, thereby impregnating the mats with the resin mixture.

A lid was then placed on the system and, after removing the remaining resin on the filter paper, the system was ^{heated to 100 1} C for 10 minutes.

The properties of the product obtained were as follows:

Tensile Strength (JIS K 6911): 300 kg / cm ² Flexural Strength (JIS K 6911) / 600 kg / cm ² Flexural Elasticity (JIS K 6911) 5 x 10 * kg / cm ² Compression Strength (JIS K 6911): 700 kg / cm ²

Example 2

Thermally curable resin: unsaturated polyester, · Polylite 0007 (product of Dai-Nippon Ink and Chemicals Inc.).

granular filler stick: particles of volcanic ash

fibrous filler: chopped strands of glass

Filter paper: filter paper No. 2 (product of Toyο Filter Paper K.K.).

The filter paper was wetted with water on the wire screen shown in Fig. 5 of the accompanying drawing placed and a sponge on the filter paper.

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brought. After the sponge with a specific Load was pressed, the filter paper was dried so that an uneven filter paper or crepe * filter paper was received *

To 4 kg of the unsaturated produced in the process Polyester was added to 40 g of Mepox peroxide (product of Kowaguchl Yakuhin E.K.) at room temperature with stirring.

The uneven filter paper obtained in the above manner was along the inner surface of the side mold 2 of the in Fig. 3 attached shape and after charging the space between the filter paper and the inner Fore 8 with a mixture of 1.5 kg of fine particles of volcanic ash and 0.6 kg of glass fibers (chopped strands old a length τοη 2.5 mm) was • in flat Filter paper attached to the top of the mold. The thus solidified form was vorertiitzt to 10O ⁰ C. The unsaturated polyester gel prepared above was poured onto the filter paper at the top of the fora, and the fora was evacuated by means of a vacuum pump through the suction hole at the bottom of the mold so that the filler in the mold was impregnated with the resin mixture.

Then, "was placed in the lid of the system for the removal of the remaining on the filter paper and the resin Systea heating to 10O ⁰ C for 10 Hinuten leave. The thus molded product had a height of 30 cm, a width of 30 cm and a length of 30 cm and a thickness of 1 cm.

The characteristics of the product were as follows:

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Flexural strength: 315 kg / cm ²

Flexural elasticity: 4.23 x 10 ⁴ kg / cat ² notched Izod impact strength: 22.2 leg cm / cm ² specific weight: 0.86

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Claims (12)

- 17 - Claims Method for molding a thermally hardening resin, characterized in that a filler is in a mold is introduced into the mold a thermosetting resin containing a solidifying agent, poured and then the resin is solidified. 2. The method according to claim 1, characterized in that the thermally curable resin is an unsaturated one Polyester resin, an epoxy resin, a phenolic resin or a polyamide resin is used. 3. The method according to claim 1 or 2, characterized in that at least one of the fiber materials is used as filler of glass fibers or asbestos fibers, at least one granular material of silica, aluminum oxide, Calcium carbonate, gypsum, talc, clay or zeolites or at least one hollow granular material made of fine hollow glass particles, hollow particles or fine hollow particles made of a phenolic resin produced by burning volcanic ashes be used. 4. A method for molding a thermosetting resin, characterized in that a microporous sheet, through which a thermosetting resin passes, but no filler passes, on the inner surface a mold is attached and then a filler is introduced into the mold or that first a filler is placed in a mold and then the microporous sheet is placed on top of the filler, in the Form a thermosetting resin, which is a solidifying agent and / or contains a solidification catalyst, is introduced and then the resin is solidified. 209823/0803 - 18 - 5 · The method according to claim 4 »characterized in that that as a microporous sheet, a cloth, a filter paper, a paper pulp material, an asbestos sheet or a Fiberglass cloth is applied. 6. The method according to claim 4 or 5, characterized thereby. indicates that a microporous sheet has at least is applied to an uneven surface. 7. The method according to claim 4 to 6, characterized in that the distance between the uneven parts of the filter paper is less than 20 mm and the height of the uneven parts is in the range of 0.05 to 1 mm. 8. The method according to claim 4 to 7, characterized in that the mold by means of a pump during casting of the resin is evacuated. 9. The method according to claim 4 to 8, characterized in that that the side form of the form with the formation of a gap between that attached to the inner form microporous arch and the side mold when pouring the resin is moved and the side mold in the original Position after. Giease of the resin is returned to this distance. 10. The method according to claim 4 to 9, characterized in that the microporous sheet and the filling, substance-containing mold is heated prior to casting the resin. 11. The method according to claim 10, characterized in that a preheating temperature which is 30 to 200 ⁰ C higher than the temperature of the resin to be cast is used. 12. The method according to claim 4 to 11, characterized in that after pouring the resin into the mold furthermore, a less shrinkable resin than this resin is poured into this mold. 209823/0803