Device for the production of polymer adhesives

Abstract

Apparatus for producing a polymer adhesive, comprising: a mixing chamber configured to be sealed from an external environment, the mixing chamber comprising: several impellers attached to the agitator shaft; and at least one sensor designed to measure in real time rheological parameters of a polymer mixture within the mixing chamber recorded; a pressure control subsystem configured to selectively operate the mixing chamber under negative pressure or positive pressure conditions; a temperature control subsystem operatively connected to the mixing chamber, the temperature control subsystem comprising a heating unit and a cooling unit configured to regulate the temperature of the polymer mixture; a crushing and screening assembly disposed above the mixing chamber, the crushing and screening assembly being configured to reduce the size of a raw material and remove impurities prior to entry into the mixing chamber; and a control unit electrically coupled to the sensor, the pressure control subsystem, and the temperature control subsystem, the control unit being programmed to: (i) receives real-time data of the rheological parameters; (ii) adjusts the negative or positive pressure in the mixing chamber based on at least some of the rheological parameters; and (iii) regulates the temperature of the polymer mixture according to the rheological parameters in order to maintain a specific processing curve.

Description

FIELD OF DISCLOSUREThe present invention relates generally to an apparatus for making polymer-based adhesives, and more particularly to an apparatus for making polymer adhesives that combines in situ rheology feedback with controlled mixing at negative and / or positive pressures to improve the quality and consistency of the final adhesive product.BACKGROUND OF THE INVENTIONPolymer adhesives - including memory adhesives and other specific polymer compounds - typically require precise temperature control, thorough mixing and controlled environmental conditions to achieve optimum performance. Conventional adhesive processing equipment generally includes heating elements, impellers, and sometimes cooling elements as well. However, such systems are often operated at ambient pressure and do not have advanced sensor feedback loops for real-time monitoring of viscosity or other rheological properties. As a result, the mixed adhesive product may exhibit variations such as trapped bubbles, uneven temperature distribution, or inconsistent polymer crosslinking.In some prior art devices, attempts have been made to remove bubbles by applying vacuum during or after mixing. However, such vacuum processing is typically performed manually or for a period of time and changes in the rheology of the polymer are not continuously monitored. Moreover, while certain mixing devices allow the user to adjust the temperature or agitation speed, these adjustments are typically based on the user's experience or fixed settings, rather than real-time sensor data indicative of viscosity changes or polymerization progress. In addition, while blends are occasionally compressed or pressed in the production of composites, such methods are rarely used in adhesive manufacturing equipment which already involves a step at reduced pressure. Thus, despite the availability of various commercial mixers, manufacturers continue to face challenges such as non-uniform product quality, suboptimal cure times, and unreliable inter-batch reproducibility.There is therefore a need for integrated devices for making polymer adhesives that (1) accurately monitor and control viscosity or other rheological parameters in real time; (2) combine vacuum and / or positive pressure modes in a single sealable mixing chamber; (3) provide effective heating and cooling functions; and (4) eliminate the need for multiple separate processing steps. The present invention fulfills these needs by providing an advanced, sensor controlled pressure / vacuum mixing apparatus for making polymer adhesives having consistent properties and improved quality.SUMMARY OF THE INVENTIONIn accordance with the foregoing and other objects, the present invention provides an apparatus for the production of polymeric adhesives which includes a sealable mixing chamber adapted for operation in both vacuum and pressure conditions. The mixing chamber is configured with a stirrer shaft having one or more stirrer blades and at least one sensor-for example a torque sensor or a viscometer-for measuring the rheological properties (e.g. the viscosity) of a polymer mixture in real time.The apparatus further includes a temperature control subsystem that may include both heating and cooling elements to enable precise temperature control during the adhesive manufacturing process. In certain embodiments, a controller (e.g., a microcontroller) continuously receives rheological data and temperature data from the sensor(s) and automatically adjusts engine speed, switches between vacuum and positive pressure modes, and / or changes heating and cooling stages within the mixing chamber. This automated control ensures that the polymer blend remains within a predetermined viscosity or temperature range during mixing and curing, thereby improving the consistency of the final adhesive product.In another aspect, the invention provides a method of making a polymer adhesive. The method comprises pretreating the raw material by crushing and sieving to remove impurities, transferring the particles thus obtained into the closable mixing chamber, and then initiating mixing and heating. As the polymer blend begins to exhibit certain rheological properties, a vacuum step is initiated to remove trapped bubbles and reduce moisture content. Subsequently or in an alternating sequence, overpressure may be applied to further homogenize the mixture or promote certain polymerization reactions. The temperature control subsystem, which is based on real-time rheological feedback, maintains proper heating or cooling, thus optimizing polymer crosslinking and ensuring consistent material properties.In further embodiments, additional sensors - for example multiple temperature sensors positioned at different locations - may be provided to eliminate hot or cold locations. A data acquisition module may record parameters such as time, temperature, viscosity, and pressure, thus improving traceability and reproducibility of the processing cycle.By combining advanced sensor controlled control with a robust mixing environment that can be operated under various printing conditions, the present invention overcomes many years of challenges in adhesive manufacturing, reduces dependency on manual interventions or estimates, and significantly improves product consistency. The apparatus thus provides an efficient, multifunctional, and automated system for reliably and reproducibly producing high performance memory adhesives or other specialized polymer adhesives.BRIEF DESCRIPTION OF THE DRAWINGSHereinafter, the present invention and its differences from the conventional technology will be described with reference to the figures and various embodiments. The figures are for illustrative purposes only and are not intended to limit the scope in any way, wherein like reference numerals refer to like components, and wherein: FIG. 1 is a schematic view of an embodiment of the polymer adhesive manufacturing apparatus. FIG. 2 is a plan view of the crushing roller of the manufacturing apparatus in this embodiment. FIG. 3 is a plan view of the vibrating screen of the manufacturing apparatus in this embodiment. FIG. 4 is a schematic view showing the installation position of the torque sensor in this embodiment. FIG. 5 is a schematic view of the bypass piping of the manufacturing apparatus in this embodiment. FIG. 6 is a block diagram of the pressure control subsystem of the manufacturing apparatus in this embodiment. FIG. 7 is a block diagram of the temperature control subsystem of the preparation apparatus in this embodiment. FIG. 8 is a flow diagram of a method of making a polymer adhesive in accordance with the present invention.DESCRIPTION OF THE PREFERRED EMBODIMENTSA preferred embodiment of the polymer adhesive preparation apparatus (hereinafter, "apparatus 100") will now be described with reference to the accompanying drawings.Referring to FIG. 1, the device 100 integrates in situ rheology monitoring and is operable under both vacuum and positive pressure conditions. This apparatus is particularly suitable for the preparation of adhesives and polymeric compositions which require precise temperature control, reduction of bubble entrapment, and stable viscosity control during processing.As shown in FIG. 1, the apparatus 100 comprises a frame 101 for supporting its various functional modules. In some embodiments, the base of the frame 101 is provided with rollers 102 and a brake mechanism (not shown) to facilitate movement and secure positioning in various production or laboratory environments. The frame 101 is usually made of steel or other robust materials capable of withstanding the vacuum and over pressure conditions.In the middle part of the frame 101 there is a closable mixing chamber 110. In one embodiment, the mixing chamber 110 includes a cylindrical outer shell 112 made of stainless steel or another pressure-resistant metal, wherein the outer shell may also have other shapes, for example a rectangular shape. In the illustrated embodiment, a cover 114 is provided on the top of the frame 101. The cover 114 includes an O-ring seal 116 or similar sealing mechanism and is configured to seal a feed port 120 in the upper portion of the mixing chamber 110 for raw materials introduced. Additionally, an outlet 122 is provided near the bottom of the mixing chamber 110 which can be actuated via a discharge valve 124 (not shown) to discharge the final polymer adhesive product. An inspection aperture 118 may also be provided on the mixing chamber to allow visual inspection using a material such as tempered glass.Referring to Figures 2 and 3, a grinding and screening arrangement 130 for pretreating the raw material is disposed above the mixing chamber 110 and below the feed port 120. As shown in FIG. 2, two counterrotating crushing rollers 132 driven by a second motor 134 crush large pieces of raw material into smaller particles. In FIG. 3, the crushed material passes through a vibrating screen 136 that includes a screen 138 configured to filter out oversized particles and contaminants. Oversized debris is discharged through a contaminant outlet 140 as the particles that meet the size criteria flow into the mixing chamber 110.Within the mixing chamber 110, a stirring shaft 150 extends vertically (or, in alternative embodiments, horizontally) and is driven by a main motor 152 disposed near the frame 101. A gear unit or direct coupling transmits the rotational force from the motor 152 to the stirring shaft 150. In some embodiments, a torque sensor 156 is disposed between the main motor 152 and the stirring shaft 150 as shown in FIG. 4 to measure real-time torque changes indicative of changes in viscosity of the mixture. The stirring shaft 150 carries a series of stirrer blades 158 arranged to promote efficient mixing and uniform temperature distribution. The wings 158 are angularly adjustable or removable so that the manufacturer can adjust the angle or number depending on the specific adhesive formulation.To track viscosity or related rheological parameters, the device 100 includes at least one sensor, such as the torque sensor 156. Alternatively, as shown in Figure 5, a bypass conduit 190 is provided in the outer shell 112 and connected to the mixing chamber 110 so that a small portion of the mixture (sample 192, the arrow in Figure 5 indicating the direction of flow of the sample) can be circulated through a viscometer 160 before being returned to the mixing chamber. In this embodiment, sample 192 is circulated through bypass line 190 by pump 194.Referring now to FIG. 6, the pressure control subsystem 170 is shown. An information communication interface 162 communicates data from the sensor(s) (i.e., the torque sensor 156 or viscometer 160) to the pressure control subsystem 170 which includes a microcontroller 171 (e.g., an PLC as manufactured by WEG). The mixing chamber 110 is connected to the pressure control subsystem 170 thereby permitting operation under vacuum and pressure conditions. Based on signals from microcontroller 171, vacuum pump 172 may be operated to exhaust air and volatiles from mixing chamber 110 while a source of positive pressure gas 174 supplies pressurized air, nitrogen or other gas to the chamber. The internal pressure of the mixing chamber 110 is controlled by a valve 175 and fluid lines 176, thereby enabling a smooth transition between vacuum, positive pressure or atmospheric pressure. One or more pressure sensors 178 monitor the internal pressure of the mixing chamber 110 and send the measured data to the microcontroller 171. If viscometer 160 detects too high or too low a viscosity, microcontroller 171 may adjust the speed of main motor 152 and thereby change the speed of stirring of blades 158.Referring now to FIG. 7, the temperature control subsystem 180 is shown. This subsystem provides that the polymer mixture can be heated or cooled as needed. The heating element 182 can be embodied as a resistor, thermoelectric module or liquid-based heat exchanger, while the cooling element 184-for example a cooling liquid circuit or an additional thermoelectric module-lowers the temperature if necessary. In the embodiment shown, a plurality of temperature sensors 186 are distributed around the mixing chamber 110 to sense hot spots or cold zones. In addition, insulation may be applied around the mixing chamber 110 to maintain a stable thermal environment and reduce power consumption.Continuing with FIGS. 6 and 7, the pressure control subsystem 170 receives information from the torque sensor 156, any inline viscometer 160, and the pressure sensor 178. The software or firmware in microcontroller 171 continuously processes this data to determine whether mixing chamber 110 is to be maintained at vacuum, pressurized, or maintained at atmospheric pressure. In addition, the microcontroller 181 of the temperature control subsystem 180 is electrically connected to the temperature sensors 186 and adjusts the temperature settings of the heating element 182 and the cooling element 184 based on the measured temperatures. In this embodiment, the heating element 182 and the cooling element 184 may be disposed within the mixing chamber 110. The apparatus 100 may further include a data logging module 210 for recording temperature, pressure and / or rheological parameter data during operation, thereby ensuring traceability of the polymer blend processing history. An operator may interact with the pressure control subsystem 170 and the temperature control subsystem 180 via a user interface 220, such as a touch screen or a computer console, thereby enabling selection of formulations, scheduling of vacuum cycles, and real-time monitoring of the process.Referring to FIG. 8, a flow chart illustrates a method of making a polymer adhesive in accordance with the present invention. Initially, in step S 110, an operator loads raw polymeric material into the grinding and screen assembly 130, with grinding rollers 132 and a screen 136 reducing particle size and removing contaminants. In step S 120, the pretreated material is fed into the mixing chamber 110 through the feed opening 120. In step S 130, once the cover 114 is sealed, the main motor 152 activates the stirring shaft 150 to homogenize the mixture into a polymer mixture. During this step, the agitation shaft 150 typically operates at medium speed while the heating element 182 provides the initial heating.As the temperature rises and the mixing progresses, the torque sensor 156 or the viscometer 160 detects changes in the viscosity of the polymer mixture in step S 140. When the polymer mixture has become sufficiently liquid in step S 150, the vacuum pump 172 is activated to remove bubbles and moisture, thereby improving the quality of the final product. After the vacuum conditions are maintained for a required time or until a predetermined viscosity threshold is reached, step S 160 is executed, in which the microcontroller 171 initiates positive pressure from the gas source 174. This pressurization aids in polymer crosslinking or the distribution of fillers within the polymer blend. During step S 170, the microcontroller 171 of the pressure regulation subsystem 170 may adjust the heating or cooling elements to maintain an optimal reaction temperature or control exothermic processes within the adhesive formulation.If viscosity measurements or other indicators show that the desired material properties (e.g., memory properties) are achieved, the device 100 enters a controlled cooling phase in step S 180. Cooling may include continued operation of the stirring shaft 150 to ensure uniform heat dissipation; if necessary, the pressure regulation subsystem 170 may restore vacuum conditions or maintain a slight positive pressure to further reduce bubbling. After the cooling phase is complete, the pressure in the mixing chamber 110 is set to atmospheric pressure, whereupon the user opens the drain valve 124 at the outlet 122 to recover the final polymer memory adhesive.The device thus offers several advantages. Real-time rheological monitoring confirms that the viscosity remains within a predetermined range, thereby reducing operator's dependence on estimates. By being able to apply vacuum conditions, trapped air and volatiles are effectively removed, while the optional pressurization step helps to compact fillers and promote cross-linking of the polymer. Multiple temperature sensors and adjustable heating and cooling elements provide a stable environment throughout the process and reduce errors caused by non-uniform heating. By integrating the grinding and screen assembly, the vacuum / pressurization modes, and the sensor-based controller in a single device, manufacturers can simplify the production process, achieve consistent adhesive performance between batches, and process a variety of specific polymer formulations.It is to be understood that various modifications may be made without departing from the scope of the appended claims.The present invention relates to an apparatus for preparing polymer adhesives under selectively controlled negative or positive pressure conditions. The device comprises a sealable mixing chamber which contains a stirrer shaft with stirrer blades and at least one sensor for rheological in situ monitoring-for example for torque-based viscosity measurement. A controller adjusts the engine speed, temperature and chamber pressure based on the measured rheological parameters, thereby allowing an automatic vacuum cycle to remove bubbles and moisture and, if desired, pressurization to improve polymer structure. A temperature control subsystem provides both heating and cooling functions to achieve precise thermal management throughout the mixing process. In certain embodiments, the raw material is crushed and sieved prior to entering the mixing chamber to ensure uniform particle size and remove contaminants.

Claims

An apparatus for making a polymer adhesive, comprising: a mixing chamber configured to be sealed from an external environment, the mixing chamber comprising: a plurality of stirrer blades attached to the stirrer shaft; and at least one sensor configured to sense real-time rheological parameters of a polymer blend within the mixing chamber; a pressure control subsystem configured to selectively operate the mixing chamber under vacuum or positive pressure conditions; a temperature control subsystem operatively connected to the mixing chamber, the temperature control subsystem comprising a heating unit and a cooling unit configured to control the temperature of the polymer blend; a grinding and screen assembly disposed above the mixing chamber, the grinding and screen assembly configured to reduce the size of a raw material and remove contaminants prior to entering the mixing chamber; and a controller electrically coupled to the sensor, the pressure control subsystem, and the temperature control subsystem, the controller programmed to: (i) receive real-time data of the rheological parameters; (ii) adjust the negative pressure or positive pressure in the mixing chamber based on at least some of the rheological parameters; and (iii) adjust the temperature of the polymer mixture according to the rheological parameters to maintain a particular processing curve.The apparatus for making a polymer adhesive of claim 1, wherein the sensor comprises a torque sensor mounted on the stirring shaft, the torque sensor configured to generate information indicative of the viscosity of the polymer blend.The apparatus for making a polymer adhesive of claim 1, wherein the controller is further programmed to dynamically adjust the speed of the agitator shaft based on at least some of the measured rheological parameters.The apparatus for making a polymer adhesive of claim 1, wherein the crushing and screening arrangement comprises: a pair of crushing rollers configured to crush a raw material supplied thereto to a certain particle size; and a vibrating screen configured to separate oversized contaminants from the material crushed by the crushing rollers prior to entering the mixing chamber.The apparatus for making a polymer adhesive of claim 1, wherein the pressure regulation subsystem comprises: a vacuum pump operable to evacuate the mixing chamber; and a positive pressure gas source configured to supply pressurized inert gas to the mixing chamber.The apparatus for manufacturing a polymer adhesive of claim 5, wherein the controller is further programmed to operate the vacuum pump and the positive pressure gas source sequentially or alternately based on changes in rheological parameters.The apparatus for making a polymer adhesive of claim 1, further comprising a data acquisition module configured to record at least one of temperature, pressure, and rheological parameters within the mixing chamber during operation, thereby ensuring traceability of the polymer blend processing history.

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