KR830002498B1 - Silicone Molding Compound Manufacturing Method - Google Patents

Abstract

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Description

Silicone Molding Compound Manufacturing Method

1 is the overall process diagram.

The present invention relates to the mixing of silicone molding compositions and more particularly silicone molding compositions using wet mixing processes.

Silicone materials are well known and highly valued for their high temperature capacity, resistance to devices and good low temperature properties. In addition, the silicone composition is a good electrical insulation material.

In the composition of electrical components, mixing of electrical components such as diodes is sometimes necessary and in the composition the resistors can handle hard solids, the composition can be at very high temperatures, the electrical material operates at high temperatures without burning the composition and the composition is electrically It is a suitable component with insulating properties.

In addition, if the composition is packaged, the electrical component is destroyed or burned due to overheating due to the flame when the component packaging does not remove toxic gases. Encapsulated configurations for electrical devices are required for several reasons. One reason is to protect the electrical components from dirt and moisture, and the other is to protect the electrical components from mechanical shock.

Thus, the encapsulated material is watertight and rigid and strong enough to allow the case to stand on its face without mechanical damage. In addition, the encapsulation of the electrical element can be done by circulating from high temperature to low temperature, ie room temperature or less, without breaking or shaking and is excellent at high temperature without burning or burning. Therefore, it is desirable to encapsulate the device in order to meet the above requirements, and the non-electric device can be continuously operated at 350 ° F. without disassembly or shaking and assistance of combustion. Silicone molding compositions are particularly suitable for this function. Thus, the molding compositions are particularly suitable for encapsulating electrical devices such as diodes and resistors and these compositions are continuously operated at 350 ° F. without combustion aid or decomposition or shaking.

Such a silicone molding composition can be circulated from low temperature to high temperature without decomposition or shaking depending on the silicone additive.

An example of such a silicone molding composition is Duane F. on December 15, 1976, "Method for producing low molecular weight silicone resin". Serial No. 750,993 filed by Merrill and Arek or USP 3,666,830 are incorporated and may be mixed. Such silicone molding compositions generally consist of silicone resins consisting of trifunctional siloxy units and high functional siloxy units, and various forms of fillers are typically in the form of precipitated or fused silica, pigments, catalyst systems and plasticizers.

Plasticizers are typically low viscosity lyconic fluids and act as plasticizing fluids in the composition, give the composition a coarse nature and are hard but not severely broken when the composition is processed.

Plasticizing fluids also impart properties to the composition in order to enable good circulation from the maximum temperature limit without decomposition or shaking.

The composition of the silicone composition, i.e., may be any of the silicone bond resins as described above.

In addition, the catalyst system may add other components, typically composed of lead compounds or carboxylic acid or carboxylic anhydride mixtures, to compositions such as pigments, other stabilizers, and the like.

If the composition is preferably used, the mixture of the components is collected, melted and injection molded in a preforming machine.

For crystallization If a silicone molding composition is satisfactorily used to encapsulate an electrical device, various tests such as gel tests and spiral flow tests are performed on the device.

One difficulty in formulations such as silicone molding compositions is to determine the final silicone molding composition having the properties required for a particular application. Accordingly, in order to solve these drawbacks or problems in the production of silicone molding compositions, various forms of binder resins have been developed and used in the manufacture of silicone molding compositions.

Other problems are important but the expansion is small and this effort is to make silicone molding compositions and to mix the various components to make the silicone molding composition particles uniform. The silicone molding composition is preferably a homogeneous mixture of the components, while all particles flow in the same ratio in the injection molding machine and the silicone molding composition melts with a uniform result and improper treatment in the injection molding machine. Therefore, it is desirable to mix all components uniformly in the silicone molding composition as far as possible until the silicone molding composition particles reach a uniform quality. Thus, in practice, the components are mixed in a Ferrell mixing system so that the components are press-mixed under pressure similar to the skew extrusion system and dry mixed. The product is collected and ground to form the desired particle size of the silicone molding composition.

Various problems are mixing systems and glass fibers are used in silicone molding compositions. These fibers do not mix uniformly with the silicone resin in the drying system. In addition, extrusion blending systems are often repaired or replaced because the fiberglass and other components are overcoated in the silicone molding composition mix. In addition, the components are mixed in a Ferrell mixing system in a dry state formed by high temperature by the mixed components while running through the mixer. The temperature is 200 ° C. or higher.

One non-development of this high temperature is the partial treatment of the silicone molding composition and the partial treatment of the silicone binder resin, i.e. the silicone molding composition does not proceed fully in the injection molding machine.

Partial processing of the molding composition reduces the auxiliary period of the silicone molding composition because of the partial processing and the molding composition proceeds too quickly in the injection molding apparatus. Moreover, this partial treatment of the molding composition is the result in different parts of the mixed composition with different temperatures in the Ferrel mixing sheath.

As a result, mixed batches of different properties are produced and mixed in one batch with uniform properties.

Moreover, these properties are varied from other batches, mixed together and made continuously or prior to the batch.

Moreover, the compositions are partially processed and cannot be manipulated in the injection molding machine and melt and break in the injection molding machine.

Therefore, for these reasons, many batches are not quality controlled and the molding composition is partially processed in the batch and the batch is inclined.

According to the present invention, there is provided a silicone molding composition constituted as follows.

(a) Mixing a silicone resin composed of RSiO ₃ ' ₂ units and R ₂ SiO units, wherein R is a monovalent hydrocarbon group, and the ratio of R and Si is 1.0 to 1.9, and is an aliphatic solvent, a ketone solvent, or an aromatic medium. Hydrocarbon solvents and aliphatic hydrocarbon solvents selected from the group consisting of and mixtures thereof form a 10 to 50% solution by weight.

(b) A solution, filler, silicone plasticizer, pigment and catalyst are added to the stirrer to form a paste having a solid weight of 85-95%.

(c) The paste is stirred to mix the ingredients overall.

(d) Removal of the residual solvent leaves the silicone molding composition and the components are mixed overall.

(e) Reduce the silicone molding composition to size the fit.

Most preferred processes are carried out in a continuous manner and steps (a), (b) and (c) are carried out at temperatures ranging from 25-50 ° C.

Preferred hydrocarbon solvents are acetone, toluene, xylene and hexane, methyl alcohol, isopropyl alcohol and mixtures thereof

Aliphatic alcohols having a weight of 5-75% of the solvent having 1 to 8 carbon atoms are preferred and more preferably isopropyl alcohol stabilizes the mixture and prevents gelation of the silicone resin in the slurry or paste mixture. The components in the silicone molding composition may be any of the standard components in the silicone molding composition or may be new and additional components, such as novel silicone binders, especially for silicone molding compositions.

In the silicone molding composition, the preparation method and the component mixing can be carried out for any of the molding components as described below.

Silicone resins are used as binder resins in silicone molding compositions and typically silicone resins are composed of RSi _3/2 units and R ₂ SiO units, with an R to Si ratio of 1.0 to 1.9 and R being a monovalent hydrocarbon group. Such resins generally have 4-8% hydroxy groups and 2-4% alkoxy groups. The R is a monovalent hydrocarbon group and any monovalent hydrocarbon group, i.e., alkyl group having 1-8 carbon atoms, methyl, ethyl, propyl, etc .: alkenyl group, ie vinyl, allyl, etc .: cycloalkyl group, ie cyclohexyl, cycloheptyl, etc. Air groups such as phenyl, ethylphenyl, ethylphenyl and the like, halogenated monovalent hydrocarbon groups, such as haloalkyl groups, for example, 3,3,3trifluoropropyl, and most preferably an aliphatic group having 1 to 8 carbon atoms, a phenyl group and a vinyl group Is selected from.

The ratio of trivalent sensory siloxy units to divalent sensory siloxy units varies from 1.0 to 1.9 to 1, most preferably from 1.0 to 1.5 to 1. Various forms of resins can be produced depending on the manufacturing process.

One preferred method for producing such silicone resins is to select organo halosilanes and hydrolyze in a mixture of acetone, water and water-soluble organic solvents, ie xylene or toluene, to produce the desired silicone resin. Preferred hydrolysis takes place in the heterogeneous hydrolysis layer and in this hydrolysis reaction the acetone acts as resin stabilizer. Hydrolyzed organo halosilanes are selected from monoorgano trihalosilanes and especially mixtures of mono-organotrichloro silanes, mono-organotrichloro silanes and diorgano dichlorosilanes and partial mixtures of alcohols The alkoxylated reaction product of the organo chlorosilanes is completed. Finally, it can be used in the reaction mixture of aliphatic alcohols having 1 to 8 carbon atoms and organo chlorosilanes, and sufficient aliphatic alcohol in the reaction mixture is substituted with 1 mole of aliphatic alcohol per mole of chlorine in the organo chlorosilanes.

Chlorosilanes are added to the heterogeneous hydrolysis mixture and then first mixed with acetone. After the hydrolyzate is prepared, the aqueous layer is separated and the silicone hydrolyzate layer is washed several times with water to remove excess acid, and the acidity is reduced by neutralization with a weak base such as acetic acid.

The resulting silicone resin is frozen by distilling off the solvent in any solid concentrate. The silicone resin can be molded by adding solvent resin solution earth and diatomaceous earth, refluxing the mixture, water can be added to the resin solvent solution, and the resulting mixture is heated at elevated temperature to partially mold the resin.

Many variations of the process can be understood and each process produces a different resin and is suitable for any application.

The resin can be prepared by the above preferred process and is dissolved in 10-50% organic solvent by weight of solids.

Other components can be added to this solution, and any solvent can be used and the resin dissolves without affecting the silicone resin.

The silicone resin can be formed in accordance with the above process and the solvent is removed by the process and the silicone resin is produced in 100% solids.

The silicone resin is redissolved in a suitable solvent for the solution to be used in the process. Moreover, in most cases, solutions of silicone resins in solvents are suited for use in the mixing process, tailored at concentrations of 10-50% by weight solids. Can be used. The solvents are water-soluble organic solvents such as keron solvents and aliphatic solvents such as aliphatic alcohol solvents, ketone solvents, ketone solvents, aromatic solvents and chlorinated hydrocarbon solvents. Preferred solvent groups are toluene, xylene, and n-hexane, methyl alcohol, isopropyl alcohol and mixtures thereof.

The solvent solution is an aliphatic alcohol solvent and especially an aliphatic alcohol having 1 to 8 carbon atoms, and these aliphatic alcohols act as stabilizers against silicone resins. That is, the silicone resin is protected from pretreatment or gelation.

Therefore, a weight of 5-75% of the total solvent is preferable, and more preferably, a weight of 20-50% of the aliphatic alcohol solvent having 1 to 8 carbon atoms stabilizes the solution. One preferred stabilizer alcohol solvent is isopropyl alcohol.

Of course, the total solvent may be an aliphatic alcohol having 1 to 8 carbon atoms and can maximize the stabilization effect of the solvent.

The alcohol is not normally used as a solvent in the silicone resin, so if the alcohol is used at a high concentration, the initial water-soluble organic solvent is removed and the alcohol is added as a solvent to form a slurry of the silicone resin in the alcohol. A stabilized solution of silicone resin is formed in the solvent.

Preferred solutions or slurries are 10-50% solids and more preferably 25-50% solids.

The slurry or solution is collected and added to the stirring device, and the stirring device is a mixing device for mixing the paste and has a stirring or mixing action. The other components of the silicone molding composition are added to the solution of the silicone resin in this slurry or solvent and once or several times to the solution or slurry. Examples of materials that may be added are rock wool glass fibers, octamerylcyclo tetrasiloxane treated fused silica, octarecanol phenylmethyl polysiloxane fluids, viscosity and benzoate, 100 to 10,000 centipoise viscosity at 25 ° C. Ikic acid or benzoic anhydride.

All of these components are added to the solution of the slurry or binder resin dissolved in the solvent once or several times in a stirring apparatus, preferably all the components are added simultaneously to make the mixture uniform.

Generally, the temperature of the stirring device is 25 ° C to 50 ° C and preferably 25 ° to 40 ° C.

Lower temperatures may be used but these lower temperatures make it difficult to stir the mixture.

If high temperatures are used, the composition may be partially cured. In addition, the addition of the components is carried out by properly mixing the components with a solution of a silicone resin solvent, which is judged according to experience.

The stirred paste produces a homogeneous mixture of ingredients and the process does not limit mixing the ingredients in advance.

Different forms of silicone molding compositions have different components, ie different components are used and mixed by the process.

A further development of the process is to mix, "lightly mix" overall.

"Lightly mixed" ingredients are fiberglass and rock wool.

The stirred paste is formed and the mixture is homogeneous in composition, then the paste is collected and heated for 15 seconds at an elevated temperature of 80-9- ° C. or higher to remove the solvent, then the product is dried and the product is ground to give a uniform particle size A uniform silicone molding composition having a composition is formed.

The solvent is collected from the top or other fans or blowers without release to the atmosphere while the solvent is collected and concentrated for reuse in the process.

In addition, in a complex process, the stirred paste can simply be collected by a spray dryer and most of the solvent is removed by spray drying to obtain particles of the silicone molding composition.

Preferably the solvent is removed by passing the superheated solvent vapor through a nebulizer in a closed system and the superheated solvent vaporizes and removes the solvent from the molding compound. The vapor is concentrated to recover 100% solvent.

This step is an improvement in the process and these particles of the silicone molding composition are pumped to the separator and the appropriate particle size is collected and stored in the storage and recycled for further processing of the other particles. For example, large particles can be recycled to a crusher for further grinding, crushed to a suitable size and passed back to the separator.

Fines are collected and recycled back to the stirring apparatus, added to the silicone molding composition and re-uniformed by mixing.

The solvent is collected, removed from the spray dryer and concentrated in a closed system to further dissolve the solvent to recycle the silicone resin to form a suitable form of paste in the stirring device.

It is noteworthy that the paste in the stirring device has a solids content of 75-95% by weight and more preferably a weight of 85-95% by weight.

While it is very important for the paste to have this concentration in the stirrer, if it is more fluid, no suitable mixing action takes place.

Thus, no suitable mixing or formation of a homogeneous mixture occurs in the slurry. The mixture has a concentration of paste and may be mixed uniformly in another form of agitator or mixing device. Therefore, the solid concentration of the mixture after adding all the components in the stirring device is very important.

The stirred paste of the mixture is stirred to homogenize and then the solvent is simply evaporated to obtain a dry material. The development of the spray dryer is to obtain a particulate material and can easily proceed in the separator. These particles are about 1-2% solvent and moreover, such solvents can in most cases be released to the atmosphere without fouling. If necessary, a suitable release device is attached to the separator to remove all solvent and collected for regeneration in the treatment or process.

The solvent removed from the spray dryer may be recycled to the stirring apparatus after removing all dust from the solvent through a dry collector.

Developmentally, overheated solvents can be used in the sprayer and when the paste is sprayed off in the spray dryer to dry, the superheated solvent can be mixed with the sprayed paste and remove the solvent from the vapor-based paste to remove 1-2 of the original solvent. Particles containing% remain.

The superheated solvent is passed through the paste and the solvent is removed from the paste, which can be collected from the spray dryer, the supernatant of the residue in the gas layer and the dust from the solvent passing through the spray dryer through the dry collector. Finally, the solvent is concentrated and reused in the required process.

Many changes can be made in this process and the necessary part of the process is paste formation by solution formation of silicone binder resin in solvent and after the solution has been collected it is added to the other components of the silicone molding composition or paste is formed in chunks at once. (Preferably 85-95% by weight of solids), and then the paste is stirred to form a paste of uniform composition.

Thus, the solvent removed from the paste is changed and specifically needed. It is necessary to show the basic steps of the present invention in this application, and furthermore, to develop the preferred method.

1 is a schematic diagram of a preferred process.

In FIG. 1, the concentrator 10 has an upper section 12, a lower section or a conical section 14, and an outer exit section 16. The mixing resin 10 is agitated by mixing a concentrator or line 20 with a silicone resin solution of 10-50% of the binder resin solution. Another silicone fluid is added via line 22, while the catalyst is added via line 24 and the colorant or pigment is added to the concentrator via line 29. Add the first form of filler through line 30 to mixer thickener 10, add the second form of filler via line 32 and the other components via line 36, and add resin solution through line 20, silicone fluid via catalyst line 22. Is added to line 24, the pigment through line 26 to add filler via line 30 and the second form of filler through line 32 to pass the other components through line 36 to the top section 12 of the concentrator.

When the paste formed in the mixing concentrator 10 is reached through the cone section 14 to the exit section 16, the uniform paste becomes a suitable size.

The process of FIG. 1 shows that the process is overall continuous and a uniform paste or preferred silice paste is released to cross section 16 of concentrator 10 and connected to line 44 through line 40 by monitor 42 and then spray dryer through line 48 by pump 46. Carried to 50.

Monitor 42 determines whether the composition or paste is in a suitable concentration in line 40 and if necessary passes solvent through monitor 42 and line 40 through line 52 to add to the composition to obtain a paste having a suitable concentration for spray dryer 50.

The spray dryer 50 has a cross section 52 and a fluidized bed 54 where dry particles of the spray dryer are formed and collected in the spray dryer.

Fresh is passed through and solvent is recycled to solvent storage tank 60 through lines 56 and 58 and passed through line 62 to evaporator 66.

The superheated solvent is passed through line 68 to bottom 70 of spray dryer 50 and through fluidized bed 54 of dry sprayer 50.

Paste passed through line 48 at spray dryer cross-section 52 with line 76 and head 78 forms particles of the silicone molding composition and falls into fluidized bed 54 of spray dryer 50. Solvent vapor goes to the spray dryer and is formed according to the vaporized solvent and fluidized bed 54 through line 68 goes to superheater 82 via line 80 and is further heated to dust collector 86 via line 84. Dust or silicone molding composition dust is removed from collector 86 and fed through line 90 into mixing tank 92 with shaker 96 and solvent addition line 97. The superheated solvent removed or purified in the dust collector 86 is passed through line 100 to concentrator 102 and liquefied the gaseous solvent and placed into recovery solvent tank 106 via line 104. The recovered solvent collected in tank 106 is passed through line 108, measured through meter 110, passed through line 112 to line 116, and connected to line 118 to recycle the recovered solvent to mixer thickener 10.

Depending on the solvent recovered in tank 106, fresh solvent in tank 120 is measured by passing meter 124 through line 122.

The fresh solvent is passed through meter 122 through line 122 and measured at line 126. The recovered solvent, purified for new solvent, is added to mixer condenser 10 via line 118 or to Arin 56 and 58 via a suitable Valbro line 130. Connect line 116 along line 112 to enter solvent tank 60. Recovered to the spray dryer 50, uniform particles of the silicone molding composition comprising 1 to 2% of the solvent in the spray dryer 50 were formed and the fluidized bed of the silicone molding composition was lined under fluidized conditions as a result of the vaporized solvent. Pass the spray dryer 50 through 68. The fluidized particles in the spray dryer 50 are collected by successively passing over the fluidized bed 54, line 140 and pump 142, line 146, cooling chamber 148, line 150 and separator 160. Separator 160 is ground to desired size and recovered to mill 170 via line 176 and to separator 160 via line 158.

Separator 160 includes a suitable product particle cross section 182 and includes a suitable size particle cross section 182 where suitable size particles are separated and put into product storage bin 188 via line 184, removing particles from product storage bin 188 and removing particles from line 190. From product storage bin 188.

Cooling gas is passed through line 192 to the bottom of separator 160 to cool the particles collected in separator 160 and from spray cooler 50 through lines 140, pump 142, line 146, coolers 148 and lines 150 and 158.

As with the cooling gas, 1-2% of the solvent remains in the particles, removed from the spray dryer, removed from the separator 160 and passed through the dust collector 198 to line 194. The purified gas containing residual solvent passes through lines 200, pumps 202 and 204. Through the atmosphere.

The fines from the dust collector 198 are fed into the fines collector 188 via line 210. Fines or dust that may be present in the storage bin 220 are passed through the dust collector 220 line 222 and the pumps 224 line 230 and line 232 into the fines mixing tank 92. The fines from separator 160 are separated at the fines separation section 240 in separator 160 and passed from storage bin 188 along line 230 through line 232 to line 242 and through line 232 to fines collection tank 92. Mix all the fines from lines 90,210 and 232 together with the required solvents, passing through mixing line 97 in collection tank 92 using a shaker 96 to form a uniform mixture of fines and mixing the fines with the mixer 92 And recover to the concentrator 10 through line 250 to form a uniform molding composition.

The overall process described above and shown in FIG. 1 are completely continuous and increase the speed by mixing and forming the composition while reducing the cost of producing the silicone molding composition mixed uniformly with the cost.

The process can be carried out on batches and on rice and is preferably continuous throughout.

The wet blending process can be used evolutionarily to produce uniformly mixed silicone molding compositions without compromising the development of previous dry mixing processes. The following examples give the actual purpose of the present invention and do not limit the object of the present invention, and all parts of the examples are by weight.

In the examples, reducing the actuality of the present invention is not carried out in a continuous method because of the present invention which is easy to reduce the actuality using batch and case-in batchwise progression.

Example 1

The following results show the mixing of a silicone molding composition with components such as solvent, toluene, hexane, acetone, hexane and give a comparison between the mixture that is mixed and dissolved in the former solvent compared with the same composition, and the dry mixed hot melt compound proceeds. It is mixed in. The properties compared in the composition show the gel time and gelation of the hot plate resin at 200 ° C.

As measured in the spiral flow test, the flow in inches of the composition is the flow of the composition before the gel on the surface in the form of a spiral and is the hot Shored property of the composition heated and cured at 177 ° C.

In all cases the mixed components are as follows.

26 parts of resin composed of 47.5 mole percent monometal trifunctional siloxy units, 47.5 mole percent monophenyl tri sensory siloxy units 5.0 mole percent dimethyldifunctional siloxy units, 0.0 mole percent diphenyl functional siloxy units, 40 parts 24 parts glass fiber, 3.1 parts of 1400 grams of octamethylcyclo tetrasiloxane treated and fused silica, 0.6 parts of phenyl-containing dimethylpolysiloxane fluids with 100 centipoise viscosity at 25 ° C., 100 centipoise viscosity at 25 ° C. 0.6 parts of phenyl-containing dimethylpolysiloxane fluid, 0.2 parts of pigment, and 0.6 parts of a mixture of lead carbonate and benze anhydride. The above components were first mixed and the resin was dissolved in the solvent shown in Table 1 below. Add other ingredients to the paste, such as the paste from the wet mixing process. It is placed on a tray of a paste vacuum brush and heated at 80-90 ° C. for 10 minutes to remove the solvent, and then pulverized the dried material to obtain a silicone molding composition having the following properties as shown in Table 1 below.

TABLE I

The results in Table 1 show that the molding compositions are obtained using the inventive properties and the comparative properties obtained using the preceding hot melt dry mixing process. In the present case, the mixer used to mix the composition is a Herbart mixer. A wet mixture of the composition is prepared as previously described and mixed in toluene using a 5 gallon dope mixer. The test results of the silicone molding compositions are tested after a homogeneous mixture of silicone molding compositions is produced as shown in the table below.

TABLE II

Results of wet process tests using solvent mixture of 5-gallon dope mixer-75% toluene and 25% isopropyl alcohol

The same composition is prepared in the same silicone molding composition prepared in accordance with the process using toluene as the solvent and a dope mixer and beaker are used as the mixing device. The test results mentioned are shown in Table III.

TABLE III

The results in Table III above show silicone molding compositions with good properties obtained using the process for mixing the components.

The silicone molding composition is also mixed in a process using 75% toluene, 25% isopropyl alcohol as solvent.

The properties of the silicone molding compositions prepared using solvents in accordance with this process are compared with the properties of the dry mix compositions having the same amounts and the same ingredients and mixed using the prior art methods and comparative products.

The results are shown in Table IV below.

TABLE IV

The results in Table IV show the wet process of producing a silicone molding composition with good silicone molding properties.

Claims (1)

Silicone resin compound of RSiO _3/2 unit and R ₂ SiO unit (wherein R is a monovalent hydrocarbon group and R to Si ratio is 1.0 to 1.8), aliphatic alcohol solvent, ketone solvent, aromatic solvent, chlorinated A mixture of hydrocarbon solvents with a hydrocarbon solvent selected from these mixtures to form a solution or slurry with a solid weight of 10 to 50%, and a filler, silicone plasticizer, pigment and catalyst are added to the solution or slurry in a stirring apparatus to give a solid weight of 75 to A method of preparing a silicone molding composition by forming a paste of 95% and mixing the components overall by stirring the paste, removing the remaining solvent from the silicone molding composition, mixing the components overall, and reducing the silicone molding composition to a suitable size. .

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