DE2235910A1 - HARDABLE EPOXY RESIN COMPOSITIONS AND METHOD FOR THEIR MANUFACTURE - Google Patents

Description

Dr. F. Zumsteln son. Dr. E. Assmann Dr. R. Koenigsberger - Dlpl.-Phys. R. Holzbauer - Dr. I-. Zumsteln jun.

PATENT LAWYERS

22J59

TELEPHONE: COLLECTIVE NO. 22 5341

TELEX 529979

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CHECK ACCOUNT: MUNICH 91139

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BANK H. HOUSES

Case 3-CNY 55 / CIP / CIP
53 / me

8 MUNICH 2,

BRÄUHAUSSTRASSE 4 / III

CIBA-GEIGY A.G., Basel / Switzerland

Curable epoxy resin compositions and methods for their preparation

The invention relates to epoxy compositions which are thermosetting and which are suitable for various process conditions and Sufficient application requirements. In general, they contain the resin and hardener together with extenders or Reinforcing agents. These latter materials cannot be dispensed with in many applications. Will these materials is used, the problem arises, a stable system from the resin, the hardening agent and the reinforcing agent

to deliver, which is converted into the desired objects by hardening can be, for example by compression molding or by Preßspritζverfahren. A simple mixing process is not suitable, especially when fillers are used, since the reinforcing materials are in the form of relatively large particles must be used to get good results. In the currently known processes for the production of curable, Resin compositions containing reinforcing agents In general, the suitable reinforcing materials or fillers coated with the resin and the hardener or impregnated. However, these methods have one or more disadvantages and hence they are useful for manufacture

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of compositions made from highly reactive components, such as Epoxy materials, unsuitable.

In the known processes, the elevated temperatures are which are required when coating or impregnating a carrier material with a resin and hardener, in the area of Temperatures used for the actual deformation and this implies that the resin and the curing agent react to an undesirable extent. Although this implementation can be very slow and relatively incomplete, depending on the particular materials that have been used will generally adversely affect the properties of the composition so that in many cases the end product is practically worthless.

In the past many attempts have been made to find a suitable solid intermediate that does not stick and is good Has hardening properties. For example, powdered hardeners have been powdered with them in the past Epoxy resins mixed. Alternatively, a solid epoxy resin was melted, the hardener added and the mixture chilled and powdered.

In order to incorporate fillers into the compositions, in in the past so-called hot-melt processes were used, in which the materials are melted at an elevated temperature, and then a reinforcing material is mixed with the hot melt. The degree> with which the material is coated with the resin and the hardener (and thus the final properties of the finished composition) depends on the viscosity of the system. The viscosity of the system is a function of itself Melt properties of the resin and the curing system and the manufacturing temperature used. Furthermore are resins and Hardeners, both of which have both low melting points and valuable properties as finished products over a wide range Own area, generally not known. This particular method has drawbacks which lead to the creation of such Materials such as epoxy melts, is not suitable.

_y 30 9885/0865

BATH ORIGINAL

Another method uses systems that are liquids per se, such as liquid resins and hardeners, to directly coat the reinforcing materials. Like the hot melt system, this system is not widely used, and after the topcoating, the epoxy system must be advanced, ie it must be cured in order to produce a solid, tack-free structure or a composite material at room temperature. It is necessary to control the curing process in order to obtain a uniform composite and thereby control process costs.

Another method uses a solvent either to lower the viscosity of the liquid systems or to make solid resin / hardener systems soluble, and then the reinforcement material is then treated with the resulting liquid. However, this procedure is associated with great difficulty when used on epoxy systems. This process requires resin and hardener dissolve in a solvent and somehow apply this solution to the reinforcing agents, such as dissolve Rovings, and then one has to remove the solvent, leaving a resin / hardener system. The main problem is in removing the solvent and a resin-hardening agent composition that has the desired physical properties when deformed. If you use To remove the solvent, high temperatures, the epoxy systems have the tendency to "advance" (to enlarge) or to pre-cure at a time when it is not "desired. On the other hand, it is used for solvent removal low temperatures, this often means that the solvent is quickly removed from the surface of the coating is removed while the solvent cannot evaporate under the surface because a tight skin has formed. This is in the case of processes in which the resin system is continuously based on filamentous or fibrous materials, such as Rovings or gauze and the like, is applied, a serious one

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Problem. In any event, compositions made from such materials often do not have the acceptable ones mechanical or electrical properties.

To date it has not been possible to achieve a satisfactory, to manufacture dry, non-adhesive, solid epoxy composite containing a solid resin as a base material, and in particular has failed to produce a dry, strong, tack-free, reinforced composite that has both

a) has good flow properties,

b) hardens quickly and

c) contains a low amount of solvent.

A variety of methods have heretofore been used to produce composites having the desired properties. In a typical known manufacturing process, either a highly functional solid resin or liquid resin is dissolved in a solvent, a hardener is added thereto and a desired substrate is impregnated or coated with it. After coating, the solvent at relatively low temperatures, typically at 121 ° C to 16O ° C (250-520 ⁰ F) is removed, and thereafter the resin to the desired level is pre-extended by allowing it to temperatures of 149 ° to 177 ° C (300 to 35O ⁰ F). In this way, a significantly advanced resin is obtained which, since it is already partially hardened, hardens very quickly. This partially cured resin still shows some flow, although this is less than that of the starting material, due to the resin / curing agent advancement. This partially cured resin, of course, has a low solvent content. Such known methods are described in US Patents 3,523,037 and 3,480,471, for example. These references generally teach that it is known to prepare pre-impregnated webs containing epoxy resins by first impregnating the carrier material used with an epoxy resin solution containing a hardening agent and then removing the solvent by treatment with heat. the

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The resulting impregnated webs can then be pressed using heat and pressure, producing laminates can. When liquid epoxy resins are used, it is generally desirable to obtain a non-tacky prepreg after impregnation. This can be achieved after the Solvent has been evaporated by keeping the impregnated sheet at a higher temperature for a period of time exposing, whereby part of the hardener reacts with the epoxy resin and the latter into a higher molecular, higher viscosity Solid is transferred, but the epoxy resin is still fusible in the "pre-extended" state (the so-called B-state).

From these explanations it can be seen that none of the known processes produces a dry, solid, tack-free, Can produce reinforced composite that has good flow properties,. cures quickly, has a low content of Has solvent and essentially retains the original epoxy value.

The invention relates to dry, solid, tack-free, curable epoxy resin compositions which contain an epoxy resin and a curing agent. The composition according to the invention is characterized by a solvent content below approximately 0.5% and a retained epoxy value of at least 75 % . The invention also provides systems in which curable epoxy resin compositions are applied to endless reinforcing materials. The invention also relates to the production of shredded prepregs for shaping, as well as impregnated filaments for filament winding, and impregnated webs for lamination.

The invention also relates to the production of curable Epoxy resin compositions. In this embodiment of the invention, an epoxy resin and a curing agent are used in one Dissolved low-boiling solvent, a reinforcing substrate such as a web, a strand or roving are passed through the solution

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and the solvent is then distilled off at elevated temperatures, whereby the resin composition by the Evaporation is cooled and pre-curing of the resin is kept low.

In another embodiment of the invention a normally solid epoxy resin and a curing agent in a low boiling solvent are dissolved and the resulting solution is dried at elevated temperatures to obtain a curable resin composition prepared by a solvent content below about O, 5 ^r $ and a maintained Epoxy value (retained epoxy value) of at least 75 % is marked. In one of these embodiments according to the invention, the solution of epoxy resin and hardener is dried at elevated temperatures, a powdered curable composition being obtained. In another embodiment of the invention, the epoxy resin and hardener solution in measured amounts is placed on an impermeable support, such as stainless steel tape, and exposed to elevated temperatures to dry the composite. The resulting curable film or tape can be peeled away from the carrier intact. Such films are useful as adhesives per se, and they can be pulverized to obtain the powdered resins. In another embodiment of the invention, the epoxy resin and hardener solution can be mixed with fillers and extenders, and the resulting composition can be placed in measured amounts on an impermeable support such as stainless steel tape and dried at elevated temperatures. The resulting composition can be removed from the substrate and ground up to obtain molding compositions for transfer molding processes and for compression molding.

An important step in the practice of the present invention is the preparation of a solution of epoxy resin and a hardener. The choice of solvent is of course important as a low boiling solvent that is used along with a fast drying step at high energy that

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Most of the energy is _{absorbed in the N} drying stage while the solvent evaporates and little, if any, energy is consumed in undesired curing or "formation of the B stage" of the epoxy resin. Generally speaking, those organic solvents which have a low boiling point at atmospheric pressure are suitable for the present invention. The term "low boiling point" means solvent boiling in the range of about 30 ⁰ C to about 100 ⁰ C at Atmosphärendruek and preferably boiling in the range of about 40 to 80 ° C. A wide variety of solvents boiling in the specified boiling range are available, and as an example the following may be cited:

Table.I ' solvent Boiling point ⁰ C Furan 51 Methyl formate 32 Diethyl ether 34.6 MethyIaI. 42 Ethyl formate 54 acetone 56.5 Methyl acetate 57 1,1-dimethoxyethane 64.5 ethyl acetate 77.1 Methyl ethyl ketone 79.6 Methyl propionate 79.7 1,2-dimethoxyethane 82.5 t-butyl acetate 97 Diet hy! Ketone 101.5

Generally speaking, the halogenated solvents are due to Their toxicity at elevated temperatures is undesirable, but if this factor does not play a role *, the halogen

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Nated solvents which boil in the specified range can also be used. The alcohols are not desirable as a solvent, as the problem may occur a potential reactivity between alcoholic groups and the epoxy groups. The preferred solvents are ketones, with acetone and methyl ethyl ketone being preferred and acetone being particularly preferred.

In fact, any epoxy resin commonly used in the manufacture of cured products can be used in the manufacture of the epoxy resin solutions described. The actual resin chosen will depend on the desired properties of the end product and therefore the choice is largely left to the discretion of the processor. The present invention is particularly suitable to treat _s quality resins, such as those that have more epoxy groups in the molecule. However, it can also be used with success with epoxy compounds that contain two or more epoxy groups. It is a particular advantage of the present invention that the functionality of the major part of the resin is retained and, therefore, it is not necessary to use polyfunctional resins and the usual and generally available resins useful in making curable epoxy resin compositions can be used . Solid, liquid and mixtures of solid and liquid resins can also be used.

The resins can be aliphatic, cycloaliphatic, aromatic, heterocyclic, and the like, and they can be inert Substituents such as chlorine and other substituents commonly used in the art. The resins can be present as monomers or as polymers, and they can also contain fit bonds and ester groups. All epoxides which are produced from a polyhydric alcohol of phenol and an epihalohydrin can be used became. Typical epoxies that are used successfully

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are those made up of epichlorohydrin and a polyhydric phenol or alcohol, such as resorcinol, catechol, 1,2,6-hexanetriol, sorbitol, mannitol, pentaerythritol, trimethylolpropane and glycerallyl ethers. On similar ones Way can polymeric materials containing polyvalent hydroxyl groups, such as appropriately substituted polyethers and Polyester. For example, you can use vinylcyclohexane dioxide, epoxidized mono-, di- and triglycerides, Butadiene dioxide, 1,4-bis- (2,3-epoxypropoxy) -benzene, l,> - bis- (2,3-epoxy.propoxy) -benzene, 4,4'-bis- (2,3-epoxy.propoxy) -diphenyl ether, 1,8-bis (2,5-epoxypropoxy) octane, 1,4-bis (2, 5-epoxypropoxy) -cyclohexane, 4,4'-bis (2-hydroxy-j5,4-epoxybutoxy) -dipheny1-dimethyl methane, 1,3-bis (4,5-epoxypentoxy) -5-chlorobenzene, 1,4-bis (3,4-epoxy.butoxy) -2-chlorocyclohexane, Diglycidylthioether, diglycidylether, ethylene glycol diglycidylether, resorcinol, diglycidylether, 1,2,5,6-diepoxyhexane-5, 1,2,5,6-diepoxyhexane and 1,2,5,4-tetra- (2-hydroxy-5,4-epoxybutoxy) butane

Particularly preferred are epoxides derived from Bls-phenol-A- (2,2-bis- [4-hydroxyphenyl] -propane) -phenols or cresols and epichlorohydrin. Bis-phenol-A-epochlorohydrin-polyepoxy resins are particularly suitable the formula

\ f Γ ³ Γ '

~ CH-CK _o -0 - C VCV VO-OU-CH-CH -O

OH 2 "2

and epoxidized poly (o-cresols) of the formula

XH "

he ι

"" CH.

.CH.

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where η, a and b are positive numbers and R is chlorohydrins, glycols, mean polymeric ether bonds and the like.

The hardeners that are ultimately used to harden the resins are those commonly used in the art can be used. It can be known hardeners, accelerators or similar substances, the polymerization of a polyepoxy resin by reacting the oxirane ring. In general, primary and secondary amines, amides, polyamines and polyamides, phenols, nova lacquers and acid anhydrides are used. Suitable hardening agents can be mentioned, for example: Amines or amides, such as aliphatic, cycloaliphatic or aromatic, primary, secondary and tertiary amines, for example Monoethanolamine, ethylenediamine, hexamethylenediamine, trimethyl! Hexamethylenediamine, Diethylenetriamine, triethylenetetramine, Tetraethylpentamine, N, N-Dimethylpropylenediamine ~ l, 3, Ν, Ν-Dläthylpropylenediamine-1,3, 2,2-bis- (4'-aminocyclohexyl) -propane, 3,5j5-trimethyl-3- (aminomethyl) -cyclohexylamine ("Isophoronediamine"), Mannich bases such as 2,4,6-tris (dimethylaminomethyl) phenol; m-phenylenediamine, p-phenylenediamine, bis (4-aminophenyl) methane, Bis (4-aminophenyl) sulfone and m-xylylenediamine; Adducts of Acrylonitrile or monoepoxides, such as ethylene oxide or propylene oxide, with polyalkylene polyamines, such as diethylenetriamine or Triethylenetetramine; Adducts of polyamines, such as diethylenetriamine or triethylenetetramine in excess, and polyepoxides, such as Bisphenol A polyglycidyl ethers; Ketimines, for example from Acetone or methyl ethyl ketone and bis (p-aminophenyl) methane; Adducts of monophenols or polyphenols and polyamines; Polyamides, especially those made from aliphatic polyamines, such as diethylenetriamine or triethylenetetramine and dimerized or trimerized unsaturated fatty acids, such as dimerized Flaxseed fatty acid ("Versamid"); polymeric polysulfide ("ThIokol"); Dicyandiamide and aniline formaldehyde resins; polyhydric phenols, for example resorcinol, 2,2-bis (4-hydroxyphenyl) propane or phenyformaldehyde resins; Boron trifluoride and its complexes with organic compounds, such as BF-z-ether complexes and BF ^ amine complexes, for example BF -, - monoethylamine complex;

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235310

Acetoacetanilide-BFp complexj phosphoric acid; Triphenylphosphitj polybasic carboxylic acid and its anhydrides, for example phthalic anhydride, A ¹ J-tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, 5,6-endomethylene-Δ-tetrahydrophthalic anhydride, 3-tetrahydroic anhydride, methyl tetrahydrophthalic anhydride, methy1-5thal anhydride. 4,5,6,7,7-HeXaChIOr-Jj, 6-endomethylene-Δ-tetrahydrophthalic anhydride 3 Succinic anhydride, adipic anhydride, azelaic anhydride, sebacic anhydride, maleic anhydride, dodecenyl-succinic anhydride, or mixtures of these anhydride, pyromethic anhydride.

The hardeners can be used singly or as mixtures of two or more hardeners. The amount used is not critical and depends on the resin, the particular hardener and the properties desired. A typical range is between 80 and 150 % of the stoichiometric amount, although the actual amount may vary from this range depending on the particular composition that is to be cured. For the purposes of stoichiometric calculations, it is assumed that an epoxy group reacts with a reactive hydrogen atom.

In addition, accelerators can be contained in the system in order to increase the rate of reaction between the hardening agent and the polyepoxide in the final application, in particular if polyhydroxides and polycarboxylic acid anhydrides are used as hardening agents. In addition, some accelerators may have primary effects as hardeners per se. Valuable accelerators are, for example, tertiary amines, their salts or quaternary ammonium compounds, for example 2,4,6-tris (dimethylaminomethyl) phenol, benzyldimethylamine, 2-ethyl-4-methyl-imidazole, triamylammonium phenolate; alkali metal alcoholates, such as for example sodium hexanetriolate, dicyandiamide (cyanoguanidine), benzoguanamine, imidazole, isoniazid, tetramethyldiamine, benzyldimethylamine, metaphenolenediamine and Ν, Ν, Ν ¹ , N ¹ -tetramethyl-1, 3 »butadiamine (TMBDA).

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The amount of accelerator is generally less than the amount of primary hardener. To the hardening implementation on To accelerate a practical rate, one can use a small amount such as 0.1 ^ of the stoichiometric amount, based on use the weight of the polyepoxide. The actual amount of However, the accelerator that is used depends on the composition that is to be cured. A major advantage of the present invention is that the epoxy hardener system can be sensitized by adding an accelerator without undesired pre-hardening.

The solution of one or more epoxy resins together with one or more curing agents and / or accelerators can further with customary modifiers, such as reactive diluents, Extenders, fillers, pigments, dyes, Plasticizers, leveling agents, fire protection materials and mold release agents be mixed. Examples of extenders, reinforcing agents, fillers and pigments used in the mixtures can be used are anthracite, bitumen, glass fibers, boron fibers, carbon fibers, cellulose, polyethylene powder, polypropylene powder, Mica, asbestos, quartz powder, slate powder, lime powder, sand, materials of dolomitic origin, including Calcium, magnesium and zinc carbonates, aluminum trihydrate, gypsum, antimony trioxide, concretes, silica airgel, lithopone, Barytes, titanium dioxide, carbon black, graphite, iron oxide or metal powder such as aluminum powder or iron powder. The epoxy resin compositions can if desired after a series of Procedures are made more flexible. For example, you can reduce the crosslinking density of the cured resins by some the epoxy groups, hardener groups or both are pre-converted. Another method of making the epoxy compositions To make it pliable or to make it flexible, consists in adding epoxy compounds that have long chains.

When preparing the epoxy resin solution, the amount of resin system (such as resin, hardener, and other soluble materials) used in the solvent system will vary. It is expedient and preferred, from 40 to 45 weight

parts solvent and from 25 to βθ parts by weight resin and to use associated hardening materials. When preparing epoxy resin solutions, the concentration of the soluble Substances be so that you get a solution that is a. has such a viscosity that they are convenient to handle can. The above ranges have been found to be appropriate for these purposes.

Virtually any reinforcement material that is continuously passed through a bath solution and at the temperatures as used in the procedures, is stable. You can use such materials as glass, boron, Graphite, silicone, ceramic fibers, sapphire filaments as well as synthetic fibers such as polyacrylonitrile, polyamide polyester and polyvinyl alcohol. These materials can be in the form of 'cloths, tapes, webs, rovings or fiberglass strands etc. can be used.

The substrate is typically impregnated with a solution of the epoxy resin, and this is accomplished by continuously passing the substrate through the epoxy resin solution at a rate sufficient for the substrate to take up the desired amount of solution. This speed depends of course on the reinforcement material used, the number of ends per strand and the number of filaments per end, the tension of the reinforcement substrate as it is passed through the solution, the viscosity of the epoxy resin solution and similar factors as they usually occur and are familiar to the person skilled in the art. Extensive coating of any material containing close-packed filaments and ends will, for tension, depend to some extent on the tautness of the fibers as they are passed through the resin solution. It has been found that the best results in the final compositions are obtained when about 20 to 60 %, based on the weight of the reinforced material being coated, is from the dry epoxy resin system coating. It should be noted that those skilled in the art can determine the amount of resin system (based on the

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Solid base with which the reinforcement material is impregnated will vary by changing a number of the process parameters as indicated above. In a Embodiment according to the invention take fiberglass rovings that 15 to J50 pieces of thread per strand and 204 to 4O8 filaments per Piece of thread contain the desired amount of resin material from the resin solution when it moves at a speed which corresponds to the temperature-velocity relationship given in FIG. 1.

After the reinforcement substrate is coated with the desired amount, the now solvent-wet composite is dried under elevated temperature conditions to essentially remove the solvent. This gives a dry resin / hardener solid system in a substantially not extended state. Alternatively, the solution of epoxy resin / hardener and filler - if present - can be subjected to high-energy drying per se, for example spray drying can be carried out at elevated temperatures, in which case the solvent is essentially removed and a resin / hardener solid system in an essentially non-extended state remains behind. It should be noted that it is not until practicing the present invention that it is possible to remove up to 99% of the solvent without promoting curing of the resin, something that has not previously been achieved. More specifically, in practicing the present invention, there is obtained a curable composition which contains a resin and a hardener or a resin, a hardener and reinforcing material, and which is characterized by having a solvent content below about 0.5 % and that the residual or maintained epoxy value is at least 75 % . The percentage of solvent is based on the total weight of the resin and substrate, if any. Under normal atmospheric environmental conditions, the upper temperature limit of the system is determined by the self-ignition point of the solvent used. However, if a layer of inert

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Gas such as nitrogen or carbon dioxide is used, even higher temperatures can be used successfully. The rate of passage of the coated, coated or impregnated substrate increases with increasing temperature, as can be seen in Figure 1. It is very desirable to use the highest speed and although it is possible to achieve speeds in excess of 15 m (50 feet) per minute, it has been found useful to adjust the temperature to achieve a speed of 1.5 to 15 feet per minute m x (5 to 50 feet) per minute, generally from about 6 m to about 1J> , 5 m (20 to 45 feet) per minute.

The temperature range can vary from approximately 204 ° C (400 ° F) to the autoignition temperature of the solvent used. Generally, the temperature range is from about 204 to about 510 ⁰ C (400 to 95O ⁰ P). As a general rule, the higher the temperature, the faster the production speed and of course the shorter the dwell time. The relationship between time and temperature should not be chosen (so great) that a remarkable hardening of the resin occurs. At the same time, however, these parameters should not be so small in value that the solvent is only incompletely removed.

As indicated above, the time and temperature factors should be adjusted so that a product is obtained which has a solvent content below about 0.5 % and a maintained epoxy value of at least 75 % .

The temperatures that are commonly used are higher than the subsequent deformation temperatures, and it is It is surprising that under these conditions there is so little pre-hardening . is observed. In fact, the process of the invention enables the curable system to be used at very high temperatures and still get less hardness than any of the other methods. Although most of them do

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Molding process is acceptable if, after removal of the solvent, greater than about 50 % of the total epoxy groups that were originally present are available for cure, then in practicing the process of the invention one easily and routinely results in resin compositions which have a residual or have a residual epoxy value of over 75 % .

In one embodiment of the invention, resin compositions that have at least a 75 $ strength remaining Epoxiwert, routinely obtained when temperatures used, as low as 149 ° C (300 ⁰ F), preferably about 204 ⁰ C to about 510 ⁰ C ( 400 to 950 ^° F) and most preferably from about 288 ^° C to about 454 ^° C (550 to 850 ^° F). This is particularly preferred when acetone is used as the only solvent.

As noted above, the properties are low in solvent retention and a higher residual epoxy value functions of treatment time and temperature, with higher Temperatures require shorter treatment times. It is preferred to have the highest temperature and the shortest residence time (dwell time) that are possible to use. For example, it has been found that one heated for one 1.8 m (6-foot) Column used as a drying tower, reinforcement material speeds from 1.5 to 15 m / min (5 to 50 feet) can use. Similar considerations apply to spray dried material.

In some cases, when reinforced material is used, it is desirable to divide the drying tower into different sections, e.g. to be divided into 3 sections and to work with temperatures that are gradually lowered. So you can, for example the part of the tower where the coated material first enters, operate at the appropriate temperature and then you can adjust the temperature in other parts depending on the lower the desired results. It was found that

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in some cases it is useful to apply compressed air directly to the overcoated material as a cooling medium as it exits the drying tower. It is also helpful in many cases to have a stream of air or nitrogen passed through the column to facilitate removal of the evaporated solvent. It is a particularly preferred embodiment of the invention to use essentially isothermal conditions in drying. The term "substantially isothermal conditions" means that the difference between the temperature of the first tower, the coated material occurs first in, and the temperature of the tower where the material exits, not more than 28 ° C (5O ⁰ F ) amounts to. Isothermal conditions are preferred because it has been found that using isothermal conditions it is possible to achieve maximum production speeds. This relationship is shown in FIG.

After the drying step, the dried material is typically collected and, if desired, collected and cut into small pieces in a manner that is well known to make chopped prepregs, or in the case of impregnated tapes, the tapes are collected and if desired cut to appropriate sizes or subsequently laminated, or in the case of a non-backed film, it will be obtained as such or crushed to give powder. Laminated articles molded or molded under pressure can then be prepared by known methods. As a result, the present invention improves manufacture such articles are facilitated by the very desirable flow and processing properties of the reinforced material.

The physical properties of the final molded products, the crushed from epoxy preimprägnierteri .vorvermischten strand form masses (crushed Prepnegs) are made, are excellent, and they have bending strengths over 3 £ 2O kg / cm ² (50,000 psi), tensile strengths exceeding 1,550 kg / cm ² 22,000 psi), impact strengths of more than 2 ^ 5 mkg per .2 ₅ 5 cm

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(18 foot pounds per inch) or 1 mkg per cm notch and a typical Barcol hardness over 60. Such epoxy-impregnated, comminuted, premixed strand molding compounds have a resin content of 3 ^ to 40 %, a fiber length of 0.6 to 2.5 cm ( 1/4 to 1 inch), a bulk wipe below 0.15, a fill constant below 1.5, and the ability to be deformed under pressure at a pressure of 66.8 kg / cm (950 psi) or less, and they are impregnated with a non-pigmented epoxy resin. As previously indicated, pigments, dyes and other fillers can be used if desired.

The present invention thus provides a method of handling epoxy systems previously thought to be they are too sensitive to make epoxy compositions. All of this is possible without looking at any of the usually foregoing desirable properties of the molding compositions got to. Materials that have been produced in the manner according to the invention can be deformed under pressure, whereby one low mold closing times at standard curing temperatures and low warpage pressures. The end result is that you can work with fast cycles, Obtain a superior product and can use low mold pressure.

The following examples illustrate the invention without, however, restricting it. In each example, unless otherwise stated, used the following procedure.

A strand of glass silk or fiberglass roving was made continuously at Room temperature passed through a bath of epoxy resin solution containing an epoxy resin, hardener and other ingredients as specified using the speed and voltage indicated. The strand of fiberglass took out of the bath Resin solution and was passed from the bath into the bottom of a 1.8 m (6 foot) vertical drying column. The dry column was divided into 0.9 to 1.2 m (2 to 3 foot) portions and heated as indicated. The tower was air at room temperature initiated to create a temperature gradient within the

Tower 3Q9885 / 0865

to accomplish. When leaving the drying tower, the coated fiberglass strand cooled with compressed air and placed in a shredding device, where it is in stacks of 1.2 cm was crushed. The shredded material was then deformed under pressure to give articles that would had specified properties.

example 1

Epoxy Resin Solution (4O % Solids)

Araldit 7O65 ¹ - 1200 g

Aniline / formaldehyde ² I38 g

Hardening agent

Acetone 1,800 g

Dimethylformamide 168 g

Water, "j6 g

Reinforcement material

Glass fiber roving - JO Ertde.-i / strand (i.e. the rovings contain 50 bundles of threads) ₅

(204 filaments / end ₅ ö h. The "", del consist of • 204 continuous threads j., ''

Roving speed m / ira ^ 2.1 (7.0) 3.0 (10) '6, ü f2 Roving tension - g 800 800 800

Tower temperature at the bottom ° c 290 J> hO 44o "in the middle ° c 275 325 425""at the upper end ° c 250 300 400

^ Content of remaining 0.3 0.3 0 3 volatile substances "

% Resin absorption. 33.3 37.3 36/9

Two of the finished products were approved in ASTM Art I a deformation temperature of 182 ° C (36o ° F), a time of 5 minutes, during which 2 hours be (300 F) post-cured. The molded pieces had the following properties:

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A C

Tensile strength at 25 ° C I5IO (21-400) I670 (23 700) kg / cm "(pci)

% Elongation to break 0.52 0.64

Material prepared in the same manner as above using the same formulation but changing the roving speed to 3 m / min (10 ft / min) and the tension being 800 g was shown in FIG cm (2 inch) 90 ° elbows deformed using standard deforming devices. The mold closing time was about 4 minutes with a mold temperature range 171-193 ° C (J4o to 38O ⁰ F) using a clamping pressure of 141 kg / cm (2000 psi) on a 35.6 cm (40 inch) die and a 120 kg 1700 psi cone pressure on a 4.4 cm (1-2 / 4 ") punch (approximately 4 minutes). The elbow has a hydrostatic pressure resistance of 173O t 15.4 kg / cm ² (2460 ί 219 psi ).

From the above results it can be seen that the inventive Process results in moldable compositions with excellent physical properties, especially for fluids

High pressure flow systems are suitable. This becomes possible using a very reactive epoxy curing agent system. For example, the above Epoxiharzlösung forms a gel in about I76 to I83 sec. At 172 ⁰ C.

Araldit 7065 is a bis-phenol Λ type of one Epoxy resin made from epichlorohydrin and has the formula, given above. It has an average epoxy value of 0.2 equivalents per 100 g and is with the CIBA Corporation, Summit, Hew Jersey.

** 2 hardeners - an aniline / formaldehyde resin (molar ratio 1 / 0.624), prepared by mixing a mixture of 608 parts of 37.0% formaldehyde and 690 parts of 31 % HCl to 1118 parts of aniline, preheated to 60 ° C , gives. . During the addition, the mixture is stirred and the temperature is kept at 90.degree. After the addition, the temperature is kept at 50 ° C. until the formaldehyde is completely consumed (approximately 2 hours). Then 540 parts of 50% sodium hydroxide are added, the aqueous layer

309885/0865

BAD ORIGfNAL

is separated and the resin is washed with water at 80 ° C until the. The pH of the washing water is 7 * 5. The volatile substances are removed in vacuo up to 130 ^° C. at 20 mm Hg.

The epoxy value is defined as the fractional number of epoxy groups per 100 g of material that is examined and it is determined by dissolving the material in a small amount of acetone, benzyl alcohol and add a water solution of bromophenol blue and potassium iodide, on reflux heated temperature and with 0.5 η hydrogen chloride acid titrated.

Example 2

The procedure of Example 1 is repeated using different Formulations and Conditions are used and the results given below are obtained.

formulation

Araldit 7064 dicyandiamide (hardener) N, N, N ¹ , N'-tetramethyl-1,3-butadiamine (TMBDA) (accelerator) acetone water dimethylformamide

Reinforcement material

Fiberglass roving - 15 ends of fiberglass strand

Roving speed 4.5 cm / min

(15 ft./min)

Roνing tension 800 - 900 g

Tower temperature C at the bottom 340

¹¹ in the middle 325.

"on the upper part. 300

% Resin uptake '32, 50

309885/0865

BATH

1200 G 48 G 3 G 1660 G 36 G 168 G

The above materials are from

a) a 5.08 cm (2 ") 90 ° elbow at 182-193 ° C

(360 - 38O ⁰ F) and a deformation pressure of 141 kg / cm

(2000 pci), a 35.6 cm (14 ") punch and a 120 kg / cr /

(I7OO pci) cone print on a 4.4 cm (1-3 / 4 ") stamp

b) a standard ASTM Type I tensile bar cured at 162 ^° C (360 ^° F) and a 1.5 t pressure until it formed a gel, and then with a pressure of 4 t until it was hardened, a mold closure time of 5 minutes (a liachhärtungszeit of 2 hours at 149 ° C [300 F ^0]), deformed.

The elbow had an average pressure resistance of 213 kg / cm ² t 14.3 kg / cm ² (3030Ϊ202 psi) (hydrostatic pressure); this means that it is an excellent material for fluid flow at high pressure. The tensile piece shows a compressive strength at 25 ° C of 1,860 kg / cm ² (26,500 psi) and an elongation to break of 0.72 ^.

The procedure was repeated using 1 g of imidazole as an accelerator in place of TMBDA. $ 32.7 of resin was picked up. An ASTM Type I tensile specimen was prepared as described above and had a tensile strength at 25 ° C of 1,790 kg / cm (25,400 psi) and a percent elongation of 0.71. Several 5.08 cm (2 ") 90 ° bends were prepared as described above under similar conditions (curing temperature of 177 - I82 p [350-360 ⁰ F]) were prepared, and they had a hydrostatic pressure resistance of 182 t 37.3 kg / cm ² (2 58O 533 psi).

Example 3

The procedure of Example 1 was repeated using the various Conditions and formulations as given below were used and the results reported received:

309885/0865 _B AD ORIGINAL

Formulation AB

Araldite 7065 1200 600 0 EClI I28O ¹ 0 600 1200 Dicyandiamine 48 72 96 Benzyl dimethylamine
(Accelerator) 6.2 5.0 3.8 water 36 54 72 acetone I660 I603.2 1538 Whore thy If ormamid 168 252 337 % Solids content
(calculated) 40 40 40 Roving tension - g 900-1000 900-1000 900-1000

Roving Visibility 3.15 (10.5) 3.3 (10.9) 3.0 (10.0) m / min, (ft./min.)

Tower temperature ⁰ C 340 340 340 on the ground

¹¹ middle 325 325 325

"at the top 300 300 300 end

Resin pick up 36.7 36.5 35.0

% volatile substances that are ₄₁ ■ _6Q

stay behind ° ^{'41 0> w} °' ^gust

Tensile strength kg / cm ² I800 I580 I080

(psi) (25 600) (22 500) (15 400) at 25 ° C (ASTM Art I)

% Elongation to break 0.69 0.61 0.67

Suitably shaped articles are obtained from any of the above formulations, although that from Composition C is lower Have tensile strength properties. The composition, which was made from only a highly functional epoxy, shows improved chemical resistance and dimensional stability under heat, and it can therefore be used in a wide variety of Conditions used useful v / earth.

* 1 ECN I28O is an epoxidized poly (o-kr

with the formula given above and a point of about 8o ^Q C. It is obtained from de * Corporaton, Summit, New Jersey:

309835 / 088S

BATH ORIGINAL

Example 4

This example shows the use of different solvent systems shown.

formulation A. ml C. G (10.2) Araldit 7065 cf. 1200 g 1200 g 1200 Example 1) G Aniline / formaldehyde 138 g 138 g I38 Hardening agent (see example 1) G acetone 2050 g I805 g I805 water 0 200 g 0 G Dimethylformamide 0 0 200 30 ends Fiberglass roving 30 ends 30 ends strand strand strand 3.05 Roving speed 3.3 (11.2) 2.95 (9.8) m / min, (ft./min.) 900 Roving tension - g 900 900 Tower temperature ⁰ C 340 on the ground 340 340 325 . center 325 325 300 at the upper end 300 300 % Residual lead content 0.3 ephemeral 0.2 0.2 Fabrics 35.7 % retained resin absorption 35.4 36.4

The ProduiJ had received ;, the one in the above method, was after it was (0.5 inch) cut into 1.27 cm staple fibers in ASTM Type I Zugbarren at a molding temperature of 182 ⁰ C (360 ⁰ F), C (300 ⁰ F) deforms a mold closing time of 5 minutes and a post curing of 2 hours at 149 °; it had the following tensile properties:

AB C

1830 (26,000) 1980 (28,100) 1000

(24 600)

Tensile strength at 25 C kg / cm ^ (psi)

% Elongation to break 0.73 0.72 0.59

From (Jp ") above that the materials particularly well f ^T ear fittings can be seen, are also suitable. In addition to going noted ö3.B one as in the formulation A, where only acetone

309885/0865

BATH ORIGINAL

Solvent is used, can use slightly higher roving speeds through the resin solution. This is of particular economic advantage. The material which was produced according to formulation A above shows a residual epoxy content of 75 to 90 % in the routine production tests. This means that such a material was only converted to the "B-stage" to the extent of 10 to 25%. This indicates an even lower tendency to elongate further compared to solvent systems that contain higher-boiling components. The degree of elongation or pre-elongation is determined by measuring the epoxy value. The epoxy value of the raw material in formulation A has an average value of 0.19 and the epoxy value of the dried material has an average value of 0.17 * a retention of 89 fo.

Example 5

To understand the relationship between the graduated tower temperature and determine the roving speed required to obtain a product with the desired properties, Identical formulations were tested at three different temperature ranges as follows:

Paint formulation grams

Araldit 7065 (see Example 1) aniline-formaldehyde hardener

(see example 1)

acetone

Glass silk strand 30 ends strand

Make -Paramet er I _-

Number of rovings. 4th

Tower temperature ⁰ C ( ⁰ F) (comparison setting)

in the upper part 200 (392) 300 (572) 400 (752)

center

on the ground ·

309885/0885

1200 III 138 4th 2050 4th

0.11 0.09 0.08 32.8 35.6 38.0 0.205 0.205 0.205 0.166 0.166 0.161 81.0 81.0 78.6

Manufacturing parameters I_ IJ III

Roving tension, kg / roving 1.0 1.0 1.0 Roving speed, m / min. 1.9 4.2 7.2

(ft./min.) (6.3) (14.0) (24.0)

Stack lengths in cm (inches) 1.27 (0.5) 1.27 (0.5) l, 27 (0.5j

Manufacturing test results

Remaining volatile substances % absorption by the binder % paint epoxy value - eq / lOO g prepreg epoxy value - eq / lOO g residual epoxy content $

The results of the above experiment are shown graphically in Figure 1, and it can be clearly seen that the relationship between the average temperature under gradient conditions and the roving speed is almost linear, approximately dr / dt = 0.0265 m / min. (0.0885 feet per minute) per degree C. For every 100 ⁰ C (212 ⁰ F) increase in the average tower temperature, the roving speed increases by about 2.65 m / foin. (8.85 ft / min.). As can be seen, at the various temperatures and different roving speeds, low volatile retention was maintained along with a high residual epoxy value.

Another observation was made. It can be seen from the above example that as the roving speed increases, the percentage of binder taken up is increased. At a given roving speed, however, the amount of binder absorbed remains constant, and a uniform product is obtained. Obviously, with all other things held constant, one way to increase the binder pick-up is to increase the roving speed. Although an increased speed 6 of the substrate decreases the time available for picking up the lacquer, which leads to a lower pick up

309835/0865

should, this is achieved by less run-off of the paint compensated during drying, so that one actually observes an increased uptake.

Example 6

From this example it can be seen that isothermal and gradient can give equivalent products at equivalent roving speeds depending on the temperature, provided that the average changing temperatures and the isothermal temperatures are equivalent, so that equivalents Amounts of energy are available. This example also shows the importance of the roving speed has to give a desired product.

Paint formulation

Araldit 7065 aniline / formaldehyde hardener acetone

Paserglas roving 30 ends of strand

Gram

1200

138

2050

Manufacturing parameters

Number of the rovings tower temperature ⁰ C

(Control setting)

on the upper part

Middle on the ground

Roving tension "~ kg / roving

Roving speed m / min.

(ft./min.)

Stack lengths in cm (inch)

11 1

160 (320) 160 (320) 180 (356)

185 (365) 185 (365) 180 (356)

200 (392) 200 (392) 180 (356)

1.0

1.0

1.0

1.8 2.6 2.6 (6.0) (8.6) (8.6)

1.27 (0.5) 1.27 (0.5) 1.27 (0.5)

31.6 32.4 32.9 0.204 0.204 0.204 0.156 0.174 0.174 76.5 85.3 85.3

Manufacturing test results

% Content of remaining η iv π 01 volatile substances ^v ' ^{l (u} ' ^dl

Binder absorption% paint epoxy value - eq / 100 g prepreg epoxy value - eq / 100 g remaining epoxy value %

From the above results, it can be seen that a prepreg having a residual epoxy value of 85.3 % and a residual amount of volatile matter of 0.21 % and 0.25 % was obtained by using a drying tower of different temperature and a. Drying tower with constant temperature and otherwise identical process parameters used. It can also be seen that at a roving speed of 1.8 m / min, a product with a residual epoxy value of 76.5 % was obtained, which indicates that the roving speed of 1.8 m / min. (6 ft / min.) Was too slow to achieve optimal properties.

Example 7

To determine the relationship between the isothermal tower temperature and the required roving speed, at to obtain a product with the desired properties, identical formulations with a variety of isothermal Temperature ranges and roving speeds examined as follows:

Paint formulation grams

1200. araldite (7065)

Aniline / formaldehyde hardener I38

Acetone 2050

Fiberglass roving 30 ends strand

309885/0865 _BAD OBlGlNAU

Tabel Roving speed m / min,
(ft./min.) 3
(10.3: 2 4.2
(14.0) 5.1
(17.0) 4.2
(14.0) 5.4
(18.0) 6.3
) 21.0) 7.2
(24.0) ro
VD % Content of remaining
volatile substances 0.114 0.162 0.733 0.077 0.038 0,201 0.272 I. % Binder absorption 32.81 3.6
(12.0) 36.30 39.10 38.20 33.49 38.00 38.64 Tower temperature
on the upper part C 240 0.158 240 240 300 300 300 300 ⁰ F 464 35.83 464 464 572 572 572 572 a * j
ο at the bottom ⁰ C 260 240 260 260 325 325 325 325 € £>
GO ⁰ p 500 464 500 500 617 617 617 617 SO
εη % Epoxy retention
(Computer results ^) 63.36 260 105.74 81.46 38.11 74.81 83.50 89.97 ο 500 QO
m 78.52

KD NJ OJ

Table 2 (continued)

(£ 3 OO 00 cn • ν. O CO cn 4Π

Roving speed m / min.
(ft./min.) 5.4 6.3 7.2 7.8 7.8 9.0 10.5 11.4 % Content of remaining : i8.0) (21.0) (24.0) (26.0) (26.0) (30.0) (35.0) (38.0) volatile substances % Binder absorption 0.095 0.148 0.155 0.132 0.094 0.086 0.189 0.304 Tower temperature 39.84 37.75 39.44 38.75 39.52 41.31 44.56 45.50 on the upper part C ⁰ F 325 325 325 325 370 370 370 370 at the bottom ⁰ C 617 617 617 617 698 698 698 698 ⁰ F 345 345 345 345 390 390 390 390 % Epoxy value retention
(Computer results,) 653 653 653 653 734 734 734 734 44.29 71.82 78.82 86.83 58.15 77.21 69.99 76.91

ro NJ OJ cn co

From the above results and from Fig. 1, in which roving speed is plotted against isothermal temperature, it can be seen that the relationship between average temperature under isothermal conditions and roving speed is linear, approximately dr / dt = OjO453 m / min. (0.151 ft / min.) Per centigrad. For each 10O ⁰ C (212 ° F) increase in temperature, the Tower roving speed un-safe 4.5 m / min can. (I5 ft / min.) Can be increased. This is an increase of approximately 71 % compared to the speed that can be achieved under gradient conditions.

Based on the reported "results, the following Relationships between temperatures and roving speed determined using a linear function with a slope of 0.151.

Roving speed m / min, (ft./min.)

Average tower temperature

O,-

300 3IO 320 330 340 350 360 370 380 390 400 410 420 430 440 450 460 470 480 490 500

When calculating the slope, results that were outside of the following parameters were not taken into account.

6.03 20.1) ) 6.3 21.7) 6.95 23.2) 7.4 24.7 7.85 26.2 8.3 27.7 8.75 29.2 9.2 30.7 9.7 32.3 10.3 33.8 10.6 35.3 11.1 36.8 11.5 38.3 11.9 39.8 12.4 41.3 12.9 42.9 13.3 44.4 13.7 45.9 14.3 14.7 15.1 < 47.4) ; 48.9) 50.4

309885/0865

223591 above

% Intake 32 - 41 %

% Retention of volatile 0 - 0.5 % / substances

$ remaining epoxy value 70 - 99 %,

Example 8

In this example, the properties of premixed staple fiberglass molding compounds that are pre-impregnated with epoxy resin are Shown as a puncture of the stack length in cm (inches).

The lacquer from Example 7 was used to produce premixed staple glass fiber molding compositions which are impregnated with epoxy resin and which contained an amount of binder of 37 * 5-2.5 % . The following table summarizes the properties of the various stack lengths. The term "binder" as used herein means the chemically active ingredients.

■ 309885/0865

Tabel

Stack length
in cm
(inch)

Amount of binder

Bulk density

Pül! Constant

Specific
weight
deformed

%. remaining
solvent

Flow kg / cm per sec (psi / sec)

Epoxy value of the structure s

0.6

O 1.27 OO (1/2) OO 1.9 en (5/4) σ
eo 2.5 05 (1.0) in

59.59 59.07 59.55

59.54

no burden / burden

0 _; 294 / 0.557

0.545 / 0.400

0.553 / 0.417

0 _? 503 / 0.371

no burden / burden

6.12 / 5.04

5.22 / 4.50

5.41 / 4.32

5.94 / 4.85

1.80
1.80
1.80

1.80,

0.38
0.22
0.29>

0.28

66.8 / 29 (950/29)

66.8 / 36 (950/36

'66, 8/48 (950/48)

66.8 / 48 (950/48)

0.054 0.054 0.054

0.054

The bulk density was determined according to method C of ASTM Standard ι D I895-69 determined. The results are given before and after applying the test load. The filling constant is determined in a similar manner according to ASTM Standard D 1895-69 certainly.

The flow corresponds to the deformation index according to the ASTM designation D 757-67 · The indicated number corresponds to Minimum force in kg / cm (pounds per square inch) that is required to close the mold, at the same time is the Closing time specified in seconds.

The bulk density of a cut prepreg is very important in relation to its use and it is measured by the end user very important. The bulk density expresses the weight per unit volume, and if the weight per unit volume is too low, i.e. if the material has too large a volume, recesses in a shape are not easily filled. The molding cycles must then contain a pre-deformation stage, which - based on the ease and simplicity of the process - is not desirable. In order to reduce the bulk density of the intermediate structure, the free flowing of the Sacrificed composite. It can be seen that the desired bulk density is that which allows for the greatest weight per unit volume and which is consistent with free flow stands. Such materials have a bulk density below un ^ about 0.20 and preferably below about 0.35

The bulk factor is a term without a single unit and indicates the relationship between the density of the molding compound and the density of the finished product shaped object. Generally speaking, it is preferred that the bulk factor be below about 1.5, and preferably below is about 1.2.

The deformation index or the flow depends on the deformation temperature and the mold pressure used. It is desirable to create a reinforced molding compound that can withstand Mold temperatures flow under relatively low mold pressures

309835/0865

will. The value of 66.8 kg / cm (950 psi) used in the example was used is the lowest pressure this one ASTM test procedure enables. Although 66.8 kg / cm is used as the molding pressure in the example, it is possible deform under pressure at mold pressures below the test minimum of 66.8 kg / cm (950 psi). Another benefit that Due to this high flow properties at low pressure is "the ability to use transfer molding to be able to.

Example 9

A lacquer was produced as described in Example 7, the formulation being modified and containing 25% ECN 1280 (cf. Example 5). This lacquer was used to prepare premixed staple fiberglass molding compositions which were impregnated with epoxy and which contained the amounts of binder as given in the table below.

309885/086 5

stack
length in
cm
(inch) Amount of
binder
in % Bulk density
g / cm ² Rubble factor Specific
weight
deformed % remaining
Solution
middle Flow
kg / cm ²
Dro sec.
(psi /
Sec. Epoxy
worth d.
Composite
fabric O
ί £>
OO
OO
cn
O
00
0)
'Jl 1.27
(1/2)
1.27
(1/2)
1.27
(1/2)
1.27
(1/2) 25.23
28.85
34.90
36.82 no loading / loading
burden 'burden
0.263 / 0.333
0.270 / 0.357
0.323 / 0.395
0.357 / 0.435 " no loading / loading
burden ' burden
7.37 / 5.82
7.02 / 5.30
5.72 / 4.79
5.04 / 4.14 1.94
1.89
1.84
1.80 0.21
0.15
0.22
0.22 138.5 / 32
(I97O / 32)
66.8 / 46
(950/46)
66.8 / 45
(950/45) 0.0401
0.0441
0.0543
0.0548
I.
I.

From the above results, it can be seen that the deformation properties of chopped prepregs within a wide range of different proportions of binder are.

It can also be seen that the length of the stack is essential has less effect on flow than the amount of binder. It is further noted that with increasing Amount of binder increases the flowability.

Chopped prepreg 'should have a bulk density below about 0.20, preferably below about 0.355 * a bulk factor below 1.5 * preferably below about 1.20, an amount of binder of 25 to 50% _s preferably from 50 to 40 <fo, a Stack length from 1.9 cm to 2.54 cm (1/4 to 1 inch), a residual solvent content below 0.5 %, preferably below 0.25 / o *, a residual epoxy value above about 75 % * preferably above 80 to 85 fo and have the ability to deform at 66.8 kg / cm (950 psi).

Example 10

This example shows the impregnation of continuous glass fabric used to make laminates can be used for manual laying as well as for wrapping processes or other foil deformation applications can be used. The impregnated cloth can of course be cut into strips or shredded, whereby reinforced molding compositions are obtained.

The glass cloth was impregnated with an impregnation solution as follows: '.

309885/086

223591Q

Araldite 7065

Aniline formaldehyde hardener acetone

Orasol Red B 10.5 %

Glass cloth I528 - es-287

g (120.8 oz.) 524.2 g (18.4 oz.) g (208.8 oz.) 1 g

(cut into lengths of 8.9 cm [3 1/2 inches])

production method

Glass tension gram tension Tower temperature ⁰ C ( ⁰ P) Glass speed m / min.

(ft./min.)

Draw weight

Setting the

Column cm (inch)

500

40O ⁰ C (752 ° F) isothermal

9.6 (32)

20 kg

0.051 cm 0.020 inch)

Experimental results of the method

% remaining volatile substances % binding agent absorption Epoxy value of the structure % remaining epoxy

0.4 32.7

0.0445 77.2

Clark - Schwebel Fiber Glass Corp. has a finish compatible with epoxy - 2l00 g / m ² (5> 94 oz / squ.yd.). Warp 42 threads; weft 32 threads.

The impregnated glass cloth was examined for its Läminierurigsariweridurigen. This study involved determining the % binder flow of the impregnated cloth as well as deforming a copper clad plate for peel strength. A laminate of four layers of 9 * 1 cm 9.1 cm (3 5/8 Irish χ 3 5/8 inch) cloth was applied at 35 kg / cm (500 psi) pressure for ten minutes in a press at 177 ° C (350 ⁰ F) deformed. To determine the percentage of binder flow, a 7.6 cm (3 inch) diameter disc was cut from the cured laminate and then determined how far? she retained the binder. The test results

309885/0865

showed a flow of 15.7 % which is within the range of commercially available laminated prepregs.

Nine layers of 9.1 cm χ 15 * 2 cm (3 5/8 χ β inch) glass laminate were made with one side containing the copper clad. The structure has been deformed (kiss gell) to give first 3 min. With gentle pressure at 177 ° C (35.O ⁰ P) and 3.5 kg / cm (50 psi) deformed, then 10 min. At 177 ⁰ C (350 ⁰ P) and 35.2 kg / cm ² (500 psi) cured. The assembly was chilled to -66 ° C (150F) in the press under a pressure of 35.3 kg / cm (500 psi), then removed and allowed to cool to room temperature before the peel strength was determined. A 1.9 cm. (3/4 inch) strip showed an average pull of 4.31 kg (9.5 pounds) at 5.0 cm (2 inches) per minute, which is 5.67 kg per 2.5 cm (12 pounds per inch) of pull ) or 2.28 kg per cm of pull. These peel strength values are similar to the values exhibited by commercially available systems and indicate that the systems of the invention can also be used in high temperature impregnation processes.

The following procedure was used to determine the epoxy value of the composites.

3.0 g (-0.3 g) epoxy composite was passed through to the nearest 0.1 g Differential. Weighed into a 500 mm Erlenmeyer flask. To this one added 25 ml of acetone and then the mixture was 10 minutes, or until the resin dissolved was stirred as determined by visual observation. 150 ml of benzyl alcohol are then poured into the Place the flask and place the flask on a hot plate with a stirrer and stir vigorously Reaction mixture heated to reflux. When the reaction mixture refluxes, 3.0 g of potassium iodide is dissolved in 5 g of distilled water together with 20 drops of indicator solution (0.1 g of bromophenol blue, diluted to 100 ml in n-propanol) added. The titration with 0.5N hydrochloric acid is then started. The titration is carried out until the indicator color disappears for one minute when 1 drop of HCl is added.

5 09885/086 5

During the titration, the comparison color shows a greenish or grayish tone and then a brown or yellow tone, which indicates an excess of HCl. The excess reacts with KJ, whereby HJ is formed, which in turn is formed by the epoxy groups is added. After the HJ has been added, the solution will slowly change color again and the indicator color will appear on. One minute is an acceptable, albeit arbitrary, amount of time to shorten the trial time. The calculation took place as follows:

τ, ^ /, _{Λ Λ} ., ml * HCl χ η HCl _1η epoxy value, eq / 100 g structure = x 10

Sample weight g

The results are approximately j5 to $ 5 below the theoretical values, and have an acceptable deviation from the average value of - 2.0%. _v

The volatile content of the compositions is determined by the difference in weight before and after heating and evaporation.

The amount of binder in the roving and glass laminate systems is determined by ignition at 704 ° C (130O ⁰ F) and the difference in weight.

The method of the present invention is not only useful for making impregnated substrates for molding and lamination uses can be used, but can also be used to make epoxy resin films or tapes without a substrate, useful in adhesive and lamination uses. If you have a continuous steel belt like that a bath of the paint, i ^ he is described in Example 7, the by adding suitable plasticizing materials, if desired can be modified, such as liquid epoxy resins and other plasticizers, and then passes this tape through a Elevated temperature environment, as described, under substantially isothermal conditions conducts and the solvent distilled off and the resulting film then from the

309885/086 5

Strips off the tape, a curable epoxy resin film is obtained without a carrier that can be used to form laminates. For example, this film can alternatively be on glass cloth and / or copper foil are laid, pressed and cured to obtain a laminate.

A varnish can be used in a similar way. Fillers or use without fillers in the above process and then crush so; to obtain a dry powder that be used for powder coating or transfer molding applications.

The term "dr / dt" means the change in roving speed with the tower temperature door.

Claims (1)

Claims 1.) A dry, solid, homogeneous, curable composition containing a usually solid epoxy resin and a hardener with a residual solvent below approximately 0.5% and a residual epoxy value of at least 75 fo. 2.) Composition according to claim 1 in the form of a powder. 2.) Composition according to claim 1 in the form of a film or tape without a backing or backing. 4.) Curable composition containing an epoxy resin, a hardener and a reinforcing material with a solvent residue of below approximately 0.5 % and a residual epoxy of at least 75 % 5.) Composition according to claim 4, wherein the reinforcing material is in the form of a web, strand, roving or filament. 6.) The composition of claim 4, wherein the reinforcing material is a web. 7.) The composition of claim 6 which is cut and shredded to give shredded prepregs. 8.) Composition according to claim 4, characterized in that the reinforcing material is in the form of a roving. 9 ·) Composition according to claim 8, which is comminuted and is in the form of shredded prepregs. Lö.) Comminuted prepregs containing from 25 to 50 % of a binder with a bulk density below about 0.20, a bulk factor below about 1.5 »a length of $ 309885/0861 ORiGlNAL 1/4 to 1 inch (0.63 to 2.5 cm) and the ability to with one Pressure of 66.8 kg / em ^ (950 psi) to be deformed. 11.) Composition according to claim 10 with a content of binder of 30 to about 40 %, a residual content of solvent below 0.25 % and a residual epoxy value above about 80 %. 12.) Chopped prepregs with a pile length of 0.63 to 2.5 ^ cm (1/4 to 1 inch), an amount of binder of 30 to 40 fo, a bulk density below about 0.20, a bulk factor below about 1 , 5 * a residual solvent content below 0.5 », a residual epoxy value above about 75 %, and the ability to be deformed at a pressure of 66.8 kg / cm (950 psi). 13.) Composition according to claim 4, wherein the reinforcement is present as a single strand or filament. \ 141) Process for the production of an epoxy composition, characterized in that an epoxy resin and a hardener are dissolved in a solvent which ^{boils from 30 to approximately 10O 0} C, and then the mixture is at a temperature of 204 to 50 ⁰ C (400 to 950 ⁰ F) exposes to evaporate the solvent, "where the temperature conditions and the treatment time are selected and regulated so that the resulting composition has a residual solvent content below about 0.5 and is substantially in the uncured state. 15.) The method according to claim 14, characterized in that the epoxy resin is a solid at room temperature. 16.) Method according to Claim 14, characterized in that the mixture is spray-dried. 3G9885 / 0865 17.) The method according to claim 14, characterized in that the mixture is applied to an impermeable carrier layer and dried under high energy conditions to form a continuous film. 18.) The method according to claim 14, characterized in that the solution of resin and binder additionally extenders and Fillers include that the mixture is coated on an impermeable carrier, the mixture under high energy conditions is dried and the resulting composition is crushed so that a powder is obtained. 19.) A method for producing a reinforced epoxy composition, characterized in that an epoxy resin and a hardener in a solvent that ^{boils at about JX) 0} to about 100 ° C, dissolves a reinforcing material through the solution and the impregnated substrate a Temperature of 204 to 510 ⁰ C (400 to 950 ⁰ F) to evaporate the solvent, the temperature conditions and the treatment time are set and regulated so that the reinforcement material at a speed of 1.5 to 15 m / min. (5 to 50 ft / min.) And that the resulting structure has a residual solvent level below about 0.5 and is substantially not precured. 20.) Method according to claim 18, characterized in that the resin solution contains 25 to 60 % resin and related hardeners. 21) The method according to claim 18, characterized in that the resulting structure 20 to 60 wt -% contains binder.. 22.) The method according to claim 18, characterized in that the impregnated substrate under substantially isothermal conditions is dried. 309885/0865 2j5.) Method according to claim 18, characterized in that that the reinforcing substrate is in the form of a roving, strand, filament or web. 24.) The method according to claim 19, characterized in that the resulting structure or the resulting composite has a residual epoxy value of over approximately 75 % . 25.) The method according to claim 18, characterized in that a reinforcing substrate containing glass or graphite rovings, strands, filaments or webs, at a speed of 1.5 to 15 m / min. (. 5 ft to 50) is passed through a solution containing from 20 to 60% epoxy resin and related hardener dissolved in a solvent to 8O ⁰ C and boils at 40 and then at the same speed through a drying tower or - tunnel, which is operated at substantially isothermal temperature of 204 to 510 ⁰ C (400 to 95O ⁰ F), is conducted to obtain a reinforced composite having a solvent residue below about 0.5 io and a residual epoxy value above owns about 75 ίο, 26.) The method according to claim 25, characterized in that that the reinforcement is in the form of a roving and that the resulting reinforced composite is comminuted, wherein comminuted prepregs are obtained. 309885/0865 L e r s e i t e