JPH04500929A - Light-curable compounds and investment casting methods - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Light-curing compound and investment casting method The present invention provides photocurable liquid compounds and tertiary products from photocurable compounds. Investment manufacturers using stereolithography to produce original objects Concerning the casting method. This compound includes thermoplastic material.

Otori SO remains 1゜ Investment casting is a common industrial method using disposable master molds. It is used to manufacture ceramic molds into which products can be cast. It will be done.

This prototype is usually made of liquid KW material, e.g. wax, thermoplastic plastic, etc. Manufactured by injection into a master cavity. This prototype cavity is usually are manufactured by conventional mechanical methods from durable materials such as aluminum, steel, etc. be done. This master model is removed from the cavity after the H-shaped material has solidified.

A refractory material, such as an aqueous ceramic slurry, is used to enclose the original form. formed around. The mold is made by heating the refractory material with the original mold enclosed inside. It is manufactured by removing the material and fusing it with a refractory material. This investment man The details of the casting process depend on the type of material poured into the mold. Alloy iron casting , used to explain conventional investment casting methods.

This prototype is coated with a continuous layer of refractory material.

Each layer is coated with fine ceramic sand and dried before applying the next layer. Typically, approximately 10 to 20 layers are used to embed the master in the refractory material. It will be done. The wrapped master is placed in an open metal container, which is This zero-order is filled with a crude slurry of ceramic back-up material. container into a furnace or autoclave. Furnace or autoclave temperature The temperature is increased until the refractory material is dried and then fused. This prototype is heated During the process, by eluting or burning off the material that makes up the original removed. The resulting fused ceramic structure is the desired mold.

Removal of the master mold ensures that the container matches the final product in shape and dimensions. A cavity is created.

This cavity (and for that matter the master) is formed during the subsequent casting process. from the final product to compensate for shrinkage or for machining if desired. can also be made slightly larger.

This mold is often filled with original material before filling this cavity with cast metal. Burn to burn off any final traces and fuse the refractory material. this The combustion process proceeds slowly in a controlled cycle, which This is done within 12 to 18 hours to avoid racking.

The cast metal is introduced into the mold cavity and allowed to cool and solidify to form the casting. let After solidification, the mold is broken and the product is removed.

The method described above is suitable for the production of cavities used in the formation of master molds. Relatively time consuming and expensive due to machining time and costs . As a result, prior art methods are not practical even when a small number of products are desired. do not have.

The prior art is also expensive if a relatively large number of products is desired. That's about it Also, this method produces a large number of prototype cavity sets with various dimensions. This is because it is necessary. This is the shrinkage of the original or the shrinkage and machining of the casting. Experience the size of the master mold (and the size of the master cavity) required to compensate This is because the decision must be made based on the A number of prototypes of various sizes are usually The product is manufactured until the appropriate size is determined to achieve the desired dimensions of the product. this Shrinkage problems can be caused by casting materials (e.g. shrinkage reaching 35% or more by volume of the cast product). This is different from cases such as eel powder materials). Prototype cartridge that eliminates expensive machining Biti is advantageous for economic and productivity reasons.

UV curing as described in U.S. Pat. No. 4,575,330 to Hull. of such material in order to solidify the upper layer of the ethylenically unsaturated liquid material. Creating complex shapes on the surface of a liquid container using computer-guided ultraviolet light It is known to mold three-dimensional objects. Partial weight formed by this method Remove the combined object from the container and harden it to strengthen it. 1 Dimensionally precise objects with thin walls are usually molded in this manner. This wall is thin Difficult objects typically have walls about 0.05 inches thick. Thicker walls are thinner walls obtained by molding into a honeycomb structure, resulting in a hollow-walled object. the purpose This method of manufacturing objects is called "stereolithography". thography) j.

This stereoreply is used to produce objects that serve as prototypes for investment casting. Attempts to utilize topography have so far been unsuccessful. This method uses ethylene Crosslinked rigid thermoset polymers produced by radiation curing on sexually unsaturated materials This is to make it into a molded prototype. In this way, this prototype does not melt when heated. Thermal expansion of this hard object, which does not expand but instead expands, causes the damage the refractory material in which the original is embedded before it can be heated sufficiently to remove it. or distort it.

Thermal expansion problems are a problem with solid objects or materials produced by stereolithography. This also occurs when objects with relatively thick solid walls are used. thick hard The body wall is formed by filling the honeycomb structure of the hollow wall object with an ethylenically unsaturated material. It can be manufactured by curing it. This method works for up to 178 inches. Objects can also be manufactured with walls up to 1/4 inch or 1/4 inch thick. . These thick-walled objects have greater strength than their thermal expansion properties. This solid Body objects and objects with thick solid walls are easier to mold than objects with thin walls. more likely to cause damage or distortion. If the mold is damaged or distorted If so, it can no longer be used.

In the present invention, the combination of stereolithography and investment casting is , providing a powerful production system. This is because this combination Enables relatively fast and inexpensive production of accurate prototypes for use in ment casting methods By achieving this, the present invention can be applied to conventional investment casting and The aforementioned drawbacks of both stereolithography and stereolithography have been overcome. More particularly, this The burden and cost of molding the original model can be reduced by molding using stereolithography. When used in investment casting methods, the resulting master mold is will not distort.

Yutaka Wataru's buttocks In accordance with the present invention, an inventive method using a stereolithographically formed master Stment casting has been shown to lose structural rigidity when exposed to elevated temperatures. That's it. Radiation polymerizable (photopolymerizable) material that can produce the above-mentioned prototype ) liquid compounds are known. Such liquid compounds are ethylene and (1) an ethylenically unsaturated material that is inert to and Thermoplastic small molecules that are soluble and (2) have a melting point below about 150°C. Consists of materials such as oligomers or compounds.

When oligomers are used, melting points below about 100° C. are advantageous. transformation If a compound is used, it is solid at ambient temperature, i.e. about 20°C to 35°C. , and has a sharp melting point below 150°C. Mixture of oligomers and compounds can also be used.

To produce a mold from a master pattern that can be produced by stereolithography The method suitable for , this material is a cross-linked polymeric matrix of radiation-curable ethylenically unsaturated materials. and this material is distributed in said thermoplastic material, and this thermoplastic material is , in an amount effective to prevent cracking or distortion of the master mold during the mold heating process. and (b) heating refractory materials and molds for the manufacture of molds; It consists of The method of embedding the prototype has been previously described in detail.

This prototype is a crosslinked thermosetting polymer of radiation polymerizable ethylenically unsaturated material. - It is a material. A readily heat-softening thermoplastic material is distributed in the matrix. Ru. When the master is heated, this thermoplastic material flows out of the matrix and Weakens the Trix and prevents its thermal expansion. This weakening of the matrix is The master is low enough to prevent mold failure such as from cracking or warping. It has a high softening point. Further heating will decompose the original and Can be baked out of the mold.

As described above, the material has a thickness of up to about 1/4 inch and comprises a conventional thermoplastic material. Solid, thick-walled prototypes manufactured from compounds that are not investment cast At the elevated temperatures used in the process, the hardness remains high enough to break the mold.

However, by manufacturing from this liquid compound and dispensing thermoplastic material into it, Solid, thin-walled and thick-walled prototypes can be used for investment casting. can. This is because this thermoplastic material flows out of the original matrix. This is because the increased temperature reduces the hardness of the original mold.

The thermoplastic compounds described above are solid at ambient temperatures and have a sharp melting temperature below about 150°C. In investment casting, compared to oligomers, it has a stereoreflection point. This further enhances the effectiveness of the target product produced by tography. This compound is It has a high melting point and transitions from the solid state to the liquid state over a relatively small temperature range. this The fluidity of the compound in the liquid state makes it easier to exclude this compound from the original form and This results in a loss of structural rigidity.

detailed description of Although the present invention exists in various forms of embodiment, it shows an advantageous embodiment of the present invention. Although this disclosure is to be considered as an example of the principles of the invention, It is understood that the invention is not limited.

The invention comprises a polymeric matrix containing a thermoplastic material distributed therein. The process of embedding the original mold into a refractory material, and the process of removing the original mold to produce the mold. It consists of a process of heating a refractory material and a master pattern, and is produced using stereolithography. This method is suitable for manufacturing a mold from a master mold manufactured by the same method. This thermoplastic material is present in an effective amount to prevent cracking or distortion of the master when heating the mold. oligomers or chemical compounds that are present in It is a compound. When using this oligomer, the melting point is below about 100°C. Advantageously, the temperature. When using compounds, ambient temperature, i.e. approximately 0°C It is solid at ~35°C and has a sharp melting point below about 150°C. Oligomer and mixtures of compounds are also suitable for use in the present invention.

In the text, "sharp melting point" means that a compound changes from a solid state to a liquid state within a narrow temperature range. It represents a transition to .

Radiation-polymerizable liquid compounds suitable for producing the prototype have been described above. child The compound consists of an ethylenically unsaturated material and a thermoplastic material.

This thermoplastic material dissolves in the ethylenically unsaturated material. This prototype is made of thermoplastic a polymeric matrix of cured ethylenically unsaturated material with interstices containing the material can be produced by curing the compound to produce .

Conventional stereolithography as described in Hull, supra. The method can be used for the production of prototypes. This radiation polymerizable (photopolymerizable) ) can be used in containers.

The object constituting the master mold cannot be used in the normal investment casting method as described above. It can be used.

This thermoplastic material is actually chemically inert, i.e. It is unreactive to pumping. In this way, thermoplastic materials are Hydroxy groups must not contain tyrenic functional groups, such as acrylic groups. or reactive groups such as carbonyl groups can be present in thermoplastic materials. However, ethylenically unsaturated materials cannot contain groups that react with this thermal The plastic material is used to radiation cure the compound from the liquid state to the solid state. No adverse effect on thermoplastics, thus having no adverse effect on curing Amine groups that chemically bond the material to the shaped polymeric matrix are eliminated is advantageous.

This thermoplastic material is fully soluble in ethylenically unsaturated materials and produced cross-linked thermal A uniform distribution of the thermoplastic material within the curable polymer matrix results. insoluble Thermoplastic materials are hardened due to the dispersion of the radiation used to harden the compound. This results in a loss of dimensional accuracy of the original model.

This thermoplastic material, suitable for use in such applications, is It must flow at a temperature lower than that which would cause mold failure or distortion ( In this case, the flow is caused by depolymerization as well as softening), and the master is heated to a temperature that destroys the mold. The degree of strength depends in part on the size, thickness and composition of the mold, the thickness of the master, etc. Ru. The presence of thermoplastic material reduces the softening temperature of the original.

The above-mentioned "depolymerization" means a decrease in molecular weight.

Such a reduction may be due to the thermoplastic material becoming softer or having a lower melting point. It causes flow by letting it fall or by partially evaporating.

The purpose is to weaken the original polymer matrix instead of destroying the mold. Is Rukoto.

The thermoplastic material advantageously has a total compound viscosity of about 10,000 cm. Add randomly until below poise (cp). This viscosity is about 200 to about Even more advantageously, it is in the range of 2000 cp.

Particularly advantageously, the viscosity is within the range of about 300 to about 800 cp. this Viscosity was measured using a Brockfield viscometer according to the instructions provided for it. The measurement is carried out using the same method at a temperature of 25°C. Low viscosity is achieved by stereolithography in one step. It is advantageous in the formation of thin layers and the test specimens are formed from liquid foam bound baths. It is also advantageous when removing.

Thermoplastic oligomers are liquids at ambient temperature. However, this compound The molded master (specimen) is solid at ambient temperature, and this liquid oligomer is held in a cross-linked polymer matrix.

Preferred thermoplastic oligomers have a molecular weight of from about 200 to about 5000, preferably from 250 to 1500. It has a number average molecular weight in the Dalton range and is a liquid or waxy solid at room temperature. Advantageously, it is soluble in ethylenically unsaturated liquids.

The above-mentioned "Dalton" is defined as a mass unit of 1/12 of the mass of carbon-12. .

The preferred oligomers have a temperature below about 100°C, particularly preferably from about 0°C to about 40°C. temperature and moderately weakens the polymer matrix upon heating, but It has maximum strength (measured by tensile modulus) at high temperatures.

This oligomer typically has a relatively high molecular weight (when compared to thermoplastic compounds). Or about ±10 special table Hei 4-500929 (5) Melts over a wider temperature range than ℃. Such oligomers have an M-type expansion. It is advantageous to have a melting point below about 100° C. to prevent tension.

The actual oligomers suitable for use in this compound are natural waxes, For example, animal wax (beeswax), vegetable wax (carnauba), mineral wax. (osikerite, paraffin, and microcrystalline petroleum), synthetic waxes (ethylene polymers, ethylenic polyol ether-esters, and chlorinated naphthalenes. ), plasticizers (alcohols having about 4 to 22 carbon atoms and ethylene Recall, lids of polyols like glycerol and pentaerythritol dioxic acid esters, adipate esters, and sebacic acid esters). with a large excess of polycarboxylic acid, such as adipic acid or trimellidic acid. Low molecular weight polyesters produced by reaction can also be used.

Combinations of the above may also be used.

Preferred thermoplastic oligomers are polyesters of low number average molecular weight, e.g. It is caprolactone polyester polyol. These are polyols, e.g. Lactate ethylene glycol, propylene glycol or butylene glycol It can be produced by polyesterification with more than two hydro Polyols with xyl groups, such as trimethylolpropane and pentaelyl Tritol can also be used. Control of lactone proportion and polyol selection is , a polyester having a desired number average molecular weight can be selected. Trio Trimethylolpropane, for example, is particularly effective in this process and It is a useful oligomer.

Two polyhydric alcohol ε-caprolactone polyesters and effective Thermoplastic oligomers are commercially available products, Tone 0301 and Tone 03]0 It is. These are manufactured by Union Carbide. p, New Y.

rk, NY). Tone 0301 is approximately 300 daltons Esterify ethylene glycol with caprolactone to obtain a number average molecular weight of This is a polyester obtained by This product is liquid at room temperature . Tone 03]0 is toned to obtain a number average molecular weight of approximately 900 Daltons. Obtained by esterifying limethylol brono with caprolactone It is polyester. This product is a wax-like solid at room temperature and is approximately 32°C. It has a melting point of

This thermoplastic compound is solid at ambient temperature and can be easily heated to soften it. can. The melting point of this thermoplastic compound is below about 150°C, advantageously about 125°C. The temperature is lower than ℃. The compound has an acute 1) melting point, advantageously approximately from a solid state to a liquid state in a temperature range of ±5°C, particularly preferably in a temperature range of about ±3°C. Typically, such compounds are relatively pure, i.e., industrial grade It is pure and pure. M-types molded from this compound are solid at ambient temperature. Ru.

Preferred thermoplastic compounds have a molecular weight of less than about 250 Daltons, preferably from about 120 to 21 Daltons. It has a number average molecular weight of 0 Daltons.

The compound may be aliphatic or aromatic in kind and may be structurally linear , which may be branched or cyclic, is monomeric in nature and at ambient temperature soluble in ethylenically unsaturated liquid compounds; non-reactive with respect to free radical reactions of body materials, and sharp at temperatures below about 150°C. Meets the requirement of having a melting point.

Suitable thermoplastic compounds include caprolactam, 2,2-dimethyl-3-hydroxy Propyl 2,2-dimethyl-3-hydroxy propyl propionate (U) Union Carbide Corp., NewYor commercially available under the trade name Esterdiol 204), Methyl terephthalate, dimethylcyclohexanol, dimethyldioxanedio and mixtures thereof.

This compound is currently the preferred thermoplastic material.

This ethylenically unsaturated material used in one step of stereolithography has a wide range of It is changeable and constant. Ethylenically unsaturated materials are thermoplastic compounds Besides ethylenic unsaturation, which ensures the avoidance of reaction with It's advantageous. Other reactive groups that are ethylenically unsaturated are those in which this group reacts with thermoplastic compounds. It is permissible only if it is not met.

Actual radiation-polymerizable liquid compounds suitable for use in the present invention include free-label Can contain liquid ethylenically unsaturated materials that polymerize due to their radical properties . This ethylenically unsaturated material is prepared by a liquid reactive diluent, preferably an ethylenically unsaturated material. The (meth)acrylate copolymerizable crosslinkable component of the resin ((meth)acrylate copolymerizable component ((meth) It consists of liquid mono(meth)acrylate, liquid mono(meth)acrylate, poly(meth)acrylate, or a mixture of such liquids, and photopolymerization initiation It may contain an agent.

The above-mentioned "(meth)acrylate" refers to acrylic acid or methacrylic acid and molybdenum. Non- or polyhydroxy compounds such as ethanol, butanol, ethylene Defined as an ester that is a reaction product with glycol, trimethylolpropane, etc. It will be done.

The above-mentioned “(meth)acrylate copolymerizable crosslinkable component” and “(meth)acrylate copolymerizable component” "Acrylate component" refers to (meth)acrylate and poly(meth)acrylate. is the same as This term has radiation polymerization properties similar to (meth)acrylates It is also the same as monomers and polymers.

The above-mentioned "reactive diluent" is a material that dissolves the (meth)acrylate component and also It is a diluent that can be polymerized.

(Meth)acrylate copolymerizable crosslinking of resins suitable for use in the present invention Possible components include monomers and polymers, with important variations possible. belongs to This (meth)acrylate component has about 1.2 or more per molecule. It preferably has a number of (meth)acrylate groups of about 2.0 or more. This (meta)acrylic Preferably, the rate component has a flowable viscosity and is stable under the processing conditions; monomers and polymers are selected until these ends are reached.

The (meth)acrylate component of the resin is, for example, the diacrylate of the epoxy functional resin. Poly(meth) containing about 2 or more (meth)acrylate groups per molecule Such diacrylates, which may be acrylates, are for example Inte Commercially available from Louisville, Inc., Louisville, KY. One example is Novacure 3700, which is Ep.

It is a diester of n828 and acrylic acid. Epon 828 is epoxy functional resin, which is diglycidyl ether of bisphenol A, 5ell Commercially available from Chemicals, New York, NY. This No. The number average molecular weight of vacure 3700 is approximately 500 Daltons, and Epon The number average molecular weight of 828 is approximately 390 Daltons.

Poly(meth)acrylate-modified polyurethane is a (meth)acrylate-modified polyurethane. In particular, it can be used as having a polyester paste.

Hydroxy-functional polyesters, especially from about 2 to about 5 hydroxy groups per molecule Urethane reaction between monoacrylate monoisocyanate and monoacrylate monoisocyanate Preference is given to the product polyacrylate-terminated polyurethane.

This poly(meth)acrylate modified polyurethane has a number average of about 600 daltons. Trimethylolpropane and caprolactone are reacted to a molecular weight, and then 1 mol of this polyester and 1 m o of 2-hydroxyethyl acrylate 1 and 3 mo1 of the reaction product of 1 mole of inphorone diisocyanate. It can be obtained from polyester produced by

The final product is a polyurethane triacrylate. The urethane production reaction is Typically, it is carried out at about 60° C. in the presence of about 1% by weight dibutyltin dilaurate.

Commercially available polyester-based polyacrylate-modified polyurethanes that can be used Lethane is Uvithane 893, Th1okol Chemica Corp., Trenton, NJ. This Uvithane The polyester product in 893 is polyesterified to an acid number below about 5. It is a reaction product of about 1.2 mol of ethylene glycol and adipic acid.

As mentioned above, this polyester is converted into polyacrylate-modified polyurethane. This polyurethane is semisolid at ambient temperature and contains 100 grams of resin. It has about 0.15 to 0.175 ethylenically unsaturated groups per ram.

In the polyester process, this acid value is required to neutralize 1 gram of polyester. It is the number of milligrams of base required and is used to monitor the progress of the reaction.

The lower the acid value, the more the reaction is progressing.

Additional polyacrylate-modified polyurethane suitable as (meth)acrylate component Tan contains a diisocyanate, a hydroxyalkyl acrylate, and a catalyst. The reaction was carried out at about 40°C for about 4 hours, and then at about 60°C for about 2 hours. reacting it with a commercially available hydroxy-terminated caprolactone polyester. This is the reaction product obtained by. The aforementioned polyacrylate-modified polyurethane is inphorone diisocyanate 1 m o I and 2-hydroxyethyl acrylate. For 1 mol of rylate and the weight of diisocyanate, acrylate and catalyst 1% by weight of dibutyltin dilaurate (catalyst) and caprolactone polyester It can be produced from 1 mol of tel. suitable caprolactone polyester is caprolactone and alkylene glycol reacted at about 60°C for 4 hours. is the reaction product of The caprolactone polyester mentioned above is caprolactone , with a polyester ratio of about 2.1. commercially available caprolactone The polyester is manufactured under the trade name Ko One M-100 (number average molecular weight approximately 345 Daltons). ), Union Carbide Corp., New York, NY. obtained from

Other ethylenically unsaturated materials suitable for use in the present invention include Potts ing Compound 363, modified acrylate (Locktite C Corporation, Newington, Conn.).

A method of making ethylenically unsaturated materials suitable for use in the present invention includes O ’　Su　　　　1　1van U.S. Pat. No. 4,100,141 There is.

The (meth)acrylate component of the resin is advantageously incorporated into one step of stereolithography. Both acrylate- and methacrylate-functional materials to minimize strain Contains. Further advantageously, this (meth)acrylate compound up to about 40% by weight of acrylate-functional material based on the weight of the thyrenically unsaturated component; (including vinyl polymers with radiation polymerization properties similar to acrylates) and Contains up to about 5% by weight methacrylate functional material.

The (meth)acrylate component of this resin is dissolved in a liquid reactive diluent, and this dilution The agent is preferably a polyethylenically unsaturated liquid material, such as poly(meth)acrylate. liquid tri(meth)acrylates, including pantriacrylates, and di(meth)acrylates, e.g. Xanthiol di(meth)acrylates are suitable. liquid tetra(meth)ac Relates such as pentaerythritol tetraacrylate may also be used. Can be done. A preferred liquid poly(meth)acrylate is 5arto+ner C9 003, has a number average molecular weight of approximately 330 Daltons and contains 2 propylene molecules per molecule. polypropoxylate modified dipentyl glycol with oxide units acrylate, and SR339,2-phenoxyethyl acrylate ( Both are commercially available from Sartomer Jersey, Chester, PA).

A suitable triacrylate as a liquid reactive diluent is Photomer 40 Propoxylated glyceryl with a number average molecular weight of 94.430 Daltons Reacrylate (from Henkel Corp, Ambler, PA) Commercially available).

The reactive diluents in this liquid are mono(meth)acrylates such as ethylenic It is an unsaturated liquid material.

Suitable materials include phenoxyethyl (meth)acrylate, hydroxyethyl (meth)acrylate, t) Acrylate, hydroxypropyl (meth)acrylate, N-vinylpyro Lydon et al. Mixtures of such ethylenically unsaturated materials are also suitable.

The liquid reactive diluent contains monoethylene in a weight ratio of about 4:1 to about 14, respectively. Advantageously, it is a mixture of polyethylene and polyethylenically unsaturated materials.

Another reactive diluent is liquid N-vinyl monomer, which is a (meth)acid. Included in the meaning of (meth)acrylate due to radiation polymerization properties similar to acrylate. shall be The N-vinyl monomers mentioned above include N-vinylpyrrolidone and N-vinylpyrrolidone. Nylcaprolactam, preferably N-vinylpyrrolidone.

Chemical energy, such as ultraviolet or near ultraviolet light and visible light, and For example, when irradiated with a light beam having a wavelength of about 200 to about 500 nanometers, A photoinitiator is used which acts to initiate radiation polymerization. This radiation polymerizable liquid The compound is supplied without photoinitiator and this photoinitiator is added prior to curing. This photoinitiator is well known and commonly used. This is usually ketonized compounds and often aromatic compounds, such as benzophenone. Daro cur1173 is a commercially available benzyl keter from EM + J6micals. 2-hydroxy-2-methyl as the active ingredient. Contains -1-phenyl-propan-1-one. C1ba Geigy Irgacur, an aryl ketone photoinitiator commercially available from Co., Ltd. e 184 is advantageous, which contains hydroxycyclohexyl fluoride as active ingredient. Contains phenyl ketone.

The above-mentioned "chemical energy" refers to the chemical energy used in radiation-polymerizable liquid compounds. It is defined as radiation that can cause changes.

The (meth)acrylate component of the resin accounts for about 15 to 15% of the weight of the ethylenically unsaturated material. Advantageously, it is present in an amount of about 80% by weight, especially about 40 to about 70% by weight.

The liquid reactive diluent is about 20% to about 80% by weight of the ethylenically unsaturated material. , particularly in an amount of about 30 to about 60% by weight.

The photoinitiator is present in an amount from about 1 to about 10% by weight of the ethylenically unsaturated material. It is advantageous to

The other reactive diluent, if effective, may contain about 1% of the weight of the ethylenically unsaturated material. Present in an amount of 0 to about 40% by weight and replaced with the same amount of (meth)acrylate component can be done.

Stabilizers and polymerization inhibitors are present in amounts less than about 1% by weight of the ethylenically unsaturated material. can exist.

Examples include methyl ether of hydroquinone.

The viscosity of the radiation-polymerizable liquid compound is incompatible with ethylenically unsaturated materials. can be adjusted using reactive and inert diluents. This diluent is Present in amounts up to about 5% by weight with respect to the renally unsaturated material. If diluent is present In this case, the amount of ethylenically unsaturated material is reduced. An example of an sf diluent is n-hexanol. be.

If the thermoplastic material is a thermoplastic oligomer, this oligomer can undergo radiation polymerization. from about 5 to about 50, preferably from about 15 to about 35, based on the total weight of the liquid compound. Present in an amount of %. Thus, ethylenically unsaturated liquid materials are radiation polymerizable from about 50 to about 95% by weight, preferably from about 65 to about 8%, based on the total weight of the liquid compound. Present in an amount within the range of 5% by weight.

If the thermoplastic material is a thermoplastic compound, this compound is a radiation-polymerizable liquid. In the range of about 5 to about 40%, preferably about 15 to about 25% by weight, based on the total weight of the compound. Exists in amounts within the range. Thus, ethylenically unsaturated liquid materials are radiation polymerizable from about 60 to about 95, preferably from about 75 to about 85, based on the total weight of the liquid compound Present in amounts within %.

Master molds made from this compound have a softening temperature of about 180°C or less.

The above-mentioned "softening temperature" refers to the temperature at which the cured compound and the master mold manufactured from it are Represents the temperature at which it loses its structural rigidity.

Typically, this object is somewhat gelatinous when removed from the container. this object The curing to a hard solid is done in the usual way, e.g. by molding a container into this object. After removal from the plant, it can be finished by exposing it to chemical energy. Another one Alternatively, the object can be cured by heat. free radical polymerization catalyst can be used to make heat curing harder and more effective at lower temperatures. Ru. Regardless of how the curing is performed, this cured object is a polymer It has thermoplastic material dispersed in the interstices of the matrix and is suitable for use as a master model. are doing.

The chemical energy suitable for curing the radiation-curable liquid Hunbound is Liconix Model 4240N.

15 milliwatts of output at 325 nanometers concentrated in a diameter of 350 microns 6 usually can be produced by a helium-cadmium laser with a The supply of It is about 3.0 joules per torr. The wavelength and supply amount of this chemical energy varies depending on the radiation-curable liquid compound used.

The following examples illustrate the invention in detail but do not limit it.

Example 1: Comparison of percent weight loss for various compounds Comparative tests were carried out using control compounds (A and B) containing no thermoplastic material; Compounds of the invention containing different thermoplastic oligomers (C, D, E and and F), and the compounds of the invention each containing a different thermoplastic compound. (G and H). These compounds are The individual components of each compound are mixed to a normal homogeneous state at ambient temperature. It can be manufactured by

'Novacure 3700, Interez Corp, Jeffer Epoxy dia, commercially available from Son, NY, having a number average molecular weight of 500 daltons. Bisphenol A mainly consists of acrylate.

” Uvitbane 893, Tb1okol Chemical Corp ,,Trenton.

Polyester-based acrylated polyurethane, commercially available from NJ.

'Epon 82g, 5hell Chemicals, New York, Diglycidyl ether of bisphenol A, commercially available from NY, this is Epon. To produce 828 diacrylate, it is reacted with 2 moles of acrylic acid.

' Photomer 4094, Henkel Corp, ^mbler, Propoxylated glycerin, commercially available from PA, with a number average molecular weight of 430 daltons. Seryl triacrylate.

Reacted with 63 mol% acrylic acid, has a number average molecular weight of 428 daltons Ethoxylated trimethylolpropane.

Reacted with 63 mol% methacrylic acid, has a number average molecular weight of 475 daltons Ethoxylated trimethylolpropane.

'5R339 is 2-phenoxyethyl acrylate, Sartomer Corp., West Bester, FA.

8. Polyethylene glycol having a number average molecular weight of about 400 Daltons.

' Tone 03] 0, Union Carbide Corp,, New commercially available from York, NY, with a number average molecular weight of 900 Daltons and a temperature of about 32°C. Thermoplastic oligomer polycaprolactone polyester polyol with melting point .

10 Caprolactam (2-oxohexamethyleneimine), 113 daltons Aldrich, a thermoplastic compound with a number average molecular weight and a melting point of 71 °C Commercially available from Chemical Co., Milwaukee JI.

” Esterdiol 204 (2,2-dimethyl-3-hydroxypropyl (2,2-dimethyl-3-hydroxypropionate), number of 204 daltons Union Car, a thermoplastic compound with an average molecular weight and a melting point of 50 °C Commercially available from Bide Corp, New York, NY.

"lrgacure 184 is an alkyl ketone photoinitiator, Ciba-G Commercially available from Eigy Corp, Oak Brook, IL.

The viscosities of compounds B, D and E were measured using a Brookfield viscometer at 2 Measured at 5°C, they were 600.520 and 620 cp, respectively.

A container containing such a radiation polymerizable liquid is placed in Liconix Mode. l 4240 N, 15 at 325 nanometers concentrated in a diameter of 350 microns UV light using helium-cadmium light with milliwatt output exposed. This feed yields a surface area of 1 square centimeter resulting in a polymeric layer approximately 20 mils thick. It was approximately 3°0 joules per meter. This layer is the same as the stereo lithograph described above. It was molded according to roughy and used as an object.

Remove the object from the container and remove any unreacted radiation-polymerizable liquid from the container. It is discharged from the na. This object is then hardened, usually in a sealed room using ultraviolet light. It became a hard solid. This hard object with a thickness of about 20 mils It was used as a prototype in the tests described below.

The prototype made from Hunbound C was extracted in methyl ethyl ketone (MEK). It generally showed about 20 to about 25% by weight. The weight percent of the extracted content is approximately the original weight of the measured weight. It is measured by immersion in MEK4 at a temperature of 25° C. for 2 hours. This prototype It was then removed from the bath, dried, weighed again, and the percent weight loss was calculated. .

As a control, thermoplastic oligomer (Tone 030 Test specimens obtained from similar dung pounds except for 1) were tested under the same conditions at 1 wt. It showed an extractable content of less than %. This is because this oligomer has reacted and hardened. It may become part of the cross-linked polymer matrix that makes up the specimen (the matrix It shows that it is independent from the system. The prototype made from compound C is At a temperature of about 250°C, it clearly softens and loses its structural hardness, but there is no dimensional change. I have shown that I do not. As a control, in Compound C, the thermoplastic oligomer was removed. Specimens made from similar compounds maintained structural stiffness at this temperature. and did not change dimensionally.

A master mold made from Compound C was covered with a refractory slurry. This slurry Allowed to dry for sufficient time to cause curing. This WL mold and slurry are Next, the master was removed and the slurry was heated to a temperature sufficient to fuse it. template was manufactured in this way.

A server that heats the masters at a controlled increasing rate (10°C/min) for each master. It was subjected to mographic analysis and the resulting weight loss was shown graphically as a function of temperature.

This analysis was performed using a thermogravimetric analyzer Model 651 (DuPont Co, Jil Mington (commercially available from Delaware) to create an operating manual. So I went. The results of the thermographic analysis are shown in Table H below.

Table■ thermographic analysis component % weight loss at specified temperature Specified temperature ('C) A B CD E F G Hloo 0 0 NA' Q OO2 220022NA' 6 4 4 17 10300 5 5 NA' 21 13 13 25 22400 26 26 NA' 56 56 56 50 46'NA = invalid The lower the temperature at which a loss of 20% by weight is reached, the more likely the prototype is for investment materials. It is more suitable for cast casting.

This weight loss occurs during the heating process in investment casting. Reduces the structural stiffness of prototypes manufactured from. Compounds D, G and H are , a loss of 20% by weight was achieved at temperatures below 300°C. This is the heat Compounds using plastic materials compared to control compounds that did not use thermoplastic materials. More suitable for use in investment casting than Pounds A and B. Which indicates that. Compounds D, G and H are Hunbound E and F A given weight % loss was achieved at temperatures lower than . However, compound E The prototype made from This shows that a loss of 20% by weight was achieved at a considerably low temperature. It is suitable for investment casting. Made from compounds A and B The molded prototype did not achieve any appreciable weight loss at sufficiently low temperatures and was susceptible to mold cracking. This may cause distortion or distortion.

Strength at ambient temperature is typically measured for compounds similar to those in Table 1 above. Table ■ shows the tensile modulus [pounds per 5 square 1 nch (p si) Expressed as ko.

Table m tensile modulus Compound tensile modulus (pis) B] 8000 The above-mentioned materials preferably exhibit softening at elevated temperatures and have adequate strength at ambient temperatures. As just indicated, Hunbound B has a relatively high elastic modulus. However, hun The prototype manufactured from Bound B did not show sufficient softening (Table ■ and accompanying theory). on the other hand, both compounds are not suitable for investment casting. D and E are suitable, with compound E having a higher tensile impact than compound D. Most suitable for showing sex rate.

According to this example, the physical Physical properties such as thermal expansion coefficient and softening point were measured. The results are shown in Table ■ .

Table■ physical properties Thermal expansion coefficient and softening point were measured using Model 943, thermomechanical analyzer, DuFo nt Co., Wilmington, Delaware. It was performed according to the method detailed by DuFont in the open manual.

The prototype made with Compound A expands without softening when heated, so it is difficult to cast. Masters made from compounds F, G or H that damage or distort the mold. may damage or distort the mold due to its relatively low coefficient of thermal expansion and relatively low softening temperature. Compounds G and H using thermoplastic compounds The prototype manufactured from Compound F, which uses thermoplastic oligomers, is The two compounds also exhibit low softening temperatures, making them suitable for investment. Suitable for use in casting.

Although the invention has been illustrated by detailed descriptions of specific embodiments, these are merely examples. However, it is not intended to limit the scope of the invention. This improvement and modification method is From the concept of the present invention, as is obvious from the disclosure and can be easily accomplished by a person skilled in the art. Improvements and variations of the above-described method without departing from this invention and the following claims therefore apply. It is considered as the range of the requested item.

Country@Investigation Report ”””””””””””” PCT/US89103301

Claims (10)

[Claims] 1. In the investment casting method, the following steps: (a) make the three-dimensional master mold refractory; embedding in a material, the master being heated to a temperature with a melting point below 150°C. Cross-linked porous radiation-cured ethylenically unsaturated material with dispersed plastic material reamer matrix, said thermoplastic material is said ethylenically unsaturated Non-reactive with the material, and during the heating process, the original will not crack or distort the mold is present in an amount that prevents (b) the refractory material is fused and the mold is manufactured by removing said master form; In this method, the refractory material is heated together with the master mold. Stment casting method. 2. The master form (1) has a melting point of less than about 100°C, and has a melting point of about 200°C to about (2) an oligomer having a number average molecular weight within the range of 5000 Daltons; manufactured from a radiation-polymerizable liquid compound consisting of an ethylenically unsaturated material; In this case, the oligomer is added to the total weight of the radiation-polymerizable compound. and the ethylenically unsaturated material is present in an amount within the range of about 5 to about 50% by weight. , from about 50 to about 95% by weight, based on the total weight of the radiation-polymerizable compound. An investment casting method according to any preceding claim. 3. The master form (1) has a melting point within a temperature range of about 10 to about 40 °C, and about 25 °C; (2) an oligomer having a number average molecular weight of 0 to about 1500 Daltons; It is produced from a radiation-polymerizable liquid compound consisting of In this case, the oligomer is added in an amount relative to the total weight of the radiation-polymerizable compound. The ethylenically unsaturated material is present in an amount within the range of about 15 to about 35% by weight; In the range of about 65 to about 85% by weight, based on the total weight of the radiation polymerizable compound. 2. The investment casting method according to claim 1, wherein: 4. The prototype has (1) a number average molecular weight of less than about 250 and a sharp melting point; A radiation polymerizable compound comprising a plastic compound and (2) the ethylenically unsaturated material. wherein said thermoplastic compound is produced from said radiation-polymerizable compound. present in the range of about 5 to about 40% by weight of the compound, and The material is present in an amount within the range of about 60% to about 95% by weight of the radiation polymerizable compound. The investment casting method according to claim 1, wherein the method comprises: 5. the prototype has (1) a number average molecular weight of about 120 to about 210 Daltons; and (2) a thermoplastic compound having a sharp melting point of less than about 125°C; Manufactured from a radiation-polymerizable liquid compound consisting of a thyrenic unsaturated material, In this case, the thermoplastic compound is about 15 to 15% of the radiation-polymerizable compound. The ethylenically unsaturated material is present in an amount within the range of about 25% by weight; Claims present in an amount within the range of about 75 to about 85% by weight of the radiation polymerizable compound. The investment casting method described in 1. 6. The thermoplastic material is caprolactam, 2,2 dimethyl-3-hydroxy Lopyl 2,2 dimethyl-3-hydroxy propyl propionate, dimethyl Chil terephthalate, dimethylcyclohexanol, dimethyldioxanedione and mixtures thereof. The method described in Section 1. 7. The mold of claim 1, wherein said master form has a softening temperature of less than about 180°C. Investment casting method. 8. (1) have a sharp melting point at a temperature below about 150°C and about 250 Dalt; (2) an ethylenically unsaturated material; and wherein said thermoplastic material is non-reactive with said ethylenically unsaturated material. and in the range of about 5 to about 40% by weight of said radiation-polymerizable compound. wherein said ethylenically unsaturated material is present in an amount within said radiation polymerizable compound. investment casting present in an amount within the range of about 60% to about 95% by weight of the A suitable radiation-polymerizable liquid compound to produce a prototype suitable for use in nd. 9. The thermoplastic compound has a melting point of less than about 125°C and has a melting point of less than about 1 the radiation polymerizable compound having a number average molecular weight of from 20 to about 210 Daltons; present in an amount within the range of about 15-25% by weight of the ethylenically unsaturated material in an amount ranging from about 75% to about 85% by weight of the radiation polymerizable compound. 9. A compound according to claim 8, wherein the compound is present. 10. The thermoplastic compounds mentioned above include caprolactam, 2,2 dimethyl-3-hydride, Roxy propyl 2,2 dimethyl-3-hydroxy propyl propione dimethyl terephthalate, dimethylcyclohexanol, dimethyldioxa thermoplastic compounds selected from the group consisting of diones and mixtures thereof. 10. A compound according to claim 9.