CN117507176A - Preparation process of fluororesin powder coating - Google Patents

Abstract

The invention discloses a preparation process of a fluororesin powder coating, which belongs to the field of powder coating production and comprises the following steps: step one, fully mixing raw materials, namely sequentially and quantitatively adding the raw materials for manufacturing the fluororesin powder coating into a mixing device according to a formula to fully mix and heat; step two, thermoplastic extrusion film forming, namely introducing the mixed and heated mixture into an extrusion device, and extruding the mixture into a coating film through extrusion and rolling; thirdly, crushing the coating film into powder, pouring the extruded coating film into a crushing device, crushing the extruded coating film into powder through the crushing device, and discharging after winnowing; and fourthly, circularly crushing the screened matters, recovering large paint film particles which are not completely crushed and screened out by one-time crushing, circularly crushing and discharging, and improving the yield.

Description

Preparation process of fluororesin powder coating

Technical Field

The invention mainly relates to the technical field of powder coating production, in particular to a preparation process of a fluororesin powder coating.

Background

The fluororesin powder coating is powder coating with fluororesin as main film forming matter; because the introduced fluorine element has high electronegativity and strong fluorocarbon bond energy, has particularly excellent weather resistance, heat resistance, low temperature resistance and chemical resistance, and has unique non-tackiness and low friction, the fluorocarbon powder coating is widely applied to various fields of buildings, chemical industry, electric and electronic industry, mechanical industry, aerospace industry and household articles, jing Jia is in front of the market, and along with the increase of the market demand of the fluorocarbon powder coating, a preparation process of the fluorocarbon powder coating with good effect is needed.

According to the powder coating production line that patent document of application number CN201610110297.6 provided, include mixer, tablet press and powder coating collecting device in proper order, the mixer with pass through the removal hopper transmission material between the mixer, remove the hopper mountable and stir on the mixer, the tablet press with pass through lift hopper transmission material between the powder coating collecting device, this powder coating production line can satisfy powder coating quick production needs.

The above patent enables rapid automated preparation of powder coatings, but has a disadvantage that mixing caused by mechanical stirring is not uniform enough when stirring and mixing powdery raw materials.

Disclosure of Invention

The invention mainly provides a preparation process of a fluororesin powder coating, which is used for solving the technical problems in the prior art.

The technical scheme adopted for solving the technical problems is as follows:

the preparation process of the fluororesin powder coating comprises the following steps:

firstly, fully mixing raw materials, namely, thermosetting chlorotrifluoroethylene-vinyl ether ester, tetrafluorochloroethylene-vinyl ether abbreviated as FEVE resin and thermoplastic polyvinylidene fluoride abbreviated as PVDF resin which are raw materials for manufacturing a fluororesin powder coating, and sequentially and quantitatively adding pigment, filler and auxiliary agent into a mixing device according to a formula to fully mix and heat;

step two, thermoplastic extrusion film forming, namely introducing the mixed and heated mixture into an extrusion device, and extruding the mixture into a coating film through extrusion and rolling;

thirdly, crushing the coating film into powder, pouring the extruded coating film into a crushing device, crushing the coating film extruded into powder by the crushing device, and blowing out the small-particle qualified powdery coating by a winnowing component;

and fourthly, circularly crushing the screened objects, collecting large paint film particles which are not completely pulverized and screened out by primary crushing through a recovery device, and reintroducing the large paint film particles into a crushing device for circularly crushing and discharging, thereby improving the yield.

The mixing device comprises a heating furnace, a first air blower arranged at one end of the heating furnace, an extrusion box arranged at one end of the inside of the extrusion box, a pushing component for extruding a mixture, two rolling wheels which are arranged at the other side of the extrusion box and are capable of rotating up and down, and a linkage component which is arranged at one side of the outside of the extrusion box and is used for cooperating with the pushing component and the rolling wheels; the crushing device comprises a crushing box, a crushing part arranged in the crushing box, a winnowing part arranged at the bottom of the crushing box, a recovery device comprises a semicircular bracket, a recovery wheel arranged in the semicircular bracket in a rotating mode, and a driving part arranged on one side of the recovery wheel.

Preferably, the heating furnace is cylindrical, and comprises a first bracket arranged at the top of the extrusion box, and a feed inlet arranged at the top of the heating furnace, wherein in the preferred embodiment, the powdery mixture can be blown up in the heating furnace through a cylindrical furnace chamber.

Preferably, the first blower comprises a supporting pile arranged at one end of the first bracket, the supporting pile is arranged, the output end of the first blower is inserted into the heating furnace and faces obliquely downwards, and in the preferred embodiment, the powder raw materials are blown up and mixed by the first blower, so that a more uniform mixing degree is achieved.

Preferably, the crushing component comprises a plurality of crushing wheels arranged in the crushing box in a plurality of crossed manner, rollers connected with the crushing wheels are arranged at one end of the crushing box, belts connected with all the rollers at the same end of the crushing box, a motor cover sleeved outside one roller, and a first motor arranged in the motor cover and connected with the rollers at the execution end of the motor cover, wherein in the preferred embodiment, the crushing wheels are used for crushing the relatively brittle coating film as much as possible, so that powdery coating is manufactured in the process.

Preferably, the winnowing component is including locating smash the case and be close to the second air-blower of extrusion case one end bottom, locate smash the screening net of the same position of case other end, locate the discharging pipe of screening net, in this preferred embodiment, will accord with the coating powder of size and blow out in the screening net through the second air-blower, guarantee that ejection of compact quality accords with the requirement.

Preferably, the driving part comprises a second motor arranged at the top of one side of the semicircular bracket, a first gear arranged at the execution end of the second motor, a thread groove meshed with the first gear and arranged at the middle part of the outer side of the recovery wheel, and in the preferred embodiment, the second motor can drive the recovery wheel to rotate on the semicircular bracket through the thread groove, and the recovery wheel is used for pouring massive paint into the crushing device again for circular crushing, so that the yield is improved.

Preferably, the pushing component comprises a plurality of spring telescopic cylinders fixed at one end inside the extrusion box, long sliding blocks arranged at execution ends of all the spring telescopic cylinders, and a pouring groove arranged at the top of the extrusion box, and in the preferred embodiment, the long sliding blocks are driven to move below the pouring groove through the spring telescopic cylinders, so that feeding and extrusion operations can be realized.

Preferably, two semi-enclosed space boxes are symmetrically arranged up and down in the discharge end of the extrusion box, parallel plates are arranged outside the discharge end of the extrusion box, the rolling wheel is rotationally connected in the space boxes, in the preferred embodiment, the rolling wheel uniformly drives the coating film to extrude, and the extruded coating film is fed into the recovery wheel through the parallel plates.

Preferably, the linkage component comprises two inner meshing ratchets which are arranged on one side outside the extrusion box and connected with the rolling wheel, two second gears which are arranged at the far end of the inner meshing ratchets in parallel, a chain which is connected with each group of inner meshing ratchets and the second gears, two long grooves which are arranged on one side of the extrusion box, and a spring telescopic cylinder which is penetrated through the long grooves and connected with the long sliding block and the chain buckle, in the preferred embodiment, the spring telescopic cylinder drives the rolling wheel to rotate when extruding materials by the linkage component, the instant cooperative operation of extrusion materials and discharging can be realized, the rolling wheel can only rotate when extruding materials by the inner meshing ratchets, the rolling wheel can not be reversed when the pushing component contracts, and the discharging is prevented from rolling back.

Compared with the prior art, the invention has the beneficial effects that:

in this embodiment, the high-power blower blows air in the cylindrical heating furnace to raise powdery raw materials, so that compared with the traditional mechanical stirring mode, the required stirring time is shorter, and the mixing effect is better.

Through the bulldozing design of extrusion case, the volume of once filming of control that can be comparatively accurate has saved extra cutting device, rolls wheel and parallel plate can make the coating film formation more even.

Through the design of retrieving the wheel, can be with the coating film that the extrusion case just extruded and the big lump materials that smash into the piece through reducing mechanism constantly circulate pour into reducing mechanism into, very big improvement the finished product proportion.

The invention will be explained in detail below with reference to the drawings and specific embodiments.

Drawings

FIG. 1 is an overall process flow diagram of the present invention;

FIG. 2 is an isometric view of the overall structure of the present invention;

FIG. 3 is a schematic view of a front half device of the present invention;

FIG. 4 is an enlarged view of a portion of the structure of the present invention;

FIG. 5 is a cross-sectional view of the front half of the device of the present invention;

FIG. 6 is a schematic diagram of a second half of the apparatus of the present invention;

fig. 7 is a cross-sectional view of the pulverizing apparatus of the present invention.

Description of the drawings: 10. a mixing device; 11. a heating furnace; 12. a first blower; 20. an extrusion device; 21. an extrusion box; 22. a pushing member; 23. a rolling wheel; 24. a linking member; 30. a pulverizing device; 31. a crushing box; 32. a crushing member; 33. a wind separation part; 40. a recovery device; 41. a semicircular bracket; 42. a recovery wheel; 43. a driving part; 111. a first bracket; 112. a feed inlet; 121. supporting piles; 321. a crushing wheel; 322. a roller; 323. a belt; 324. a motor cover; 325. a first motor; 331. a second blower; 332. screening a net; 333. a discharge pipe; 431. a second motor; 432. a first gear; 433. a thread groove; 221. a spring telescoping cylinder; 222. a long slide block; 223. a material pouring groove; 211. a compartment; 212. a parallel plate; 241. an inner engagement ratchet; 242. a second gear; 243. a chain; 244. a long groove; 245. and (5) a buckle.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

Examples

Referring to fig. 1, 2, 3 and 5, the preparation process of the fluororesin powder coating comprises the following steps:

firstly, fully mixing raw materials, namely, thermosetting chlorotrifluoroethylene-vinyl ether ester, tetrafluorochloroethylene-vinyl ether abbreviated as FEVE resin and thermoplastic polyvinylidene fluoride abbreviated as PVDF resin which are raw materials for manufacturing a fluororesin powder coating, and sequentially and quantitatively adding pigment, filler and auxiliary agent into a mixing device 10 according to a formula to fully mix and heat;

step two, thermoplastic extrusion film forming, wherein the mixed and heated mixture is led into an extrusion device 20, and the mixture is extruded into a coating film through extrusion and rolling;

thirdly, crushing the coating film into powder, pouring the extruded coating film into a crushing device 30, crushing the coating film extruded into powder by the crushing device 30, and blowing out the small-particle qualified powdery coating by a winnowing component 33;

step four, the screened material is circularly crushed, the large paint film particles which are not completely crushed and screened out by primary crushing are collected by the recovery device 40, and are reintroduced into the crushing device 30, and the material is circularly crushed and discharged, so that the yield is improved.

The mixing device 10 comprises a heating furnace 11, a first air blower 12 arranged at one end of the heating furnace 11, an extrusion box 21 arranged at the extrusion device 20, a pushing component 22 arranged at one end of the inside of the extrusion box 21 and used for extruding a mixture, two rolling wheels 23 arranged at the other side of the extrusion box 21 and used for improving the forming quality in a vertically rotatable manner, and a linkage component 24 arranged at one side of the outside of the extrusion box 21 and used for cooperating with the pushing component 22 and the rolling wheels 23; the crushing device 30 comprises a crushing box 31, a crushing part 32 arranged in the crushing box 31, a winnowing part 33 arranged at the bottom of the crushing box 31, a recovery device 40 comprising a semicircular bracket 41, a recovery wheel 42 rotatably arranged in the semicircular bracket 41, a driving part 43 arranged on one side of the recovery wheel 42, a cylindrical heating furnace 11 comprising a first bracket 111 arranged at the top of the extrusion box 21, a feed inlet 112 arranged at the top of the heating furnace 11, a first blower 12 comprising a support pile 121 arranged at one end of the first bracket 111 and a support pile 121, wherein the output end of the first blower 12 is inserted into the heating furnace 11 and faces obliquely downwards.

The feeding port 112 is funnel-shaped with wide upper part and narrow lower part, so that powdery raw materials poured into the heating furnace 11 are prevented from being raised by the blower and gushed out from the inlet, the output end of the first blower 12 blows obliquely downwards, the raw materials can roll on the cylindrical heating furnace 11 in a shoveling bottom, and the mixing efficiency is high;

further, a first blower 12 is started, strong circulating air is formed in the heating furnace 11, thermosetting chlorotrifluoroethylene-vinyl ether ester, tetrafluorochloroethylene-vinyl ether and thermoplastic polyvinylidene fluoride are sequentially and quantitatively added into the heating furnace 11 according to a formula, and the pigments, the fillers and the auxiliary agents are stirred and mixed by the circulating air;

further, the heating furnace 11 heats the mixture, melting the resin-based raw material, so that the mixture thickens.

Referring to fig. 2, 3, 4 and 5, the pushing member 22 includes a plurality of spring telescopic cylinders 221 fixed at one end of the inside of the extrusion box 21, a long sliding block 222 disposed at the execution end of all the spring telescopic cylinders 221, a material pouring slot 223 disposed at the top of the extrusion box 21, two spaced boxes 211 vertically symmetrically disposed at the discharge end of the extrusion box 21, a parallel plate 212 disposed at the outside of the discharge end of the extrusion box 21, a rolling wheel 23 rotatably connected in the spaced boxes 211, a linkage member 24 including two inner engaging ratchet wheels 241 disposed at one side of the outside of the extrusion box 21 and connected with the rolling wheel 23, two second gears 242 parallel disposed at the distal ends of the inner engaging ratchet wheels 241, a chain 243 connecting each group of inner engaging ratchet wheels 241 and the second gears 242, two elongated slots 244 disposed at one side of the extrusion box 21, and a buckle 245 penetrating the elongated sliding block 222 and connecting the chain 243.

It should be noted that, the length of the extrusion space of the extrusion box 21 is smaller than the length of the long slide block 222, the long groove 244 is located at the end of the movable position of the long slide block 222 to prevent the mixture from leaking out, the pouring groove 223 is disposed right above the extrusion space of the extrusion box 21, and the pouring groove 223 is closed in the process that the long slide block 222 is pushed forward; when the long slide block 222 is pulled backwards, the pouring chute 223 is conducted

Further, the spring telescopic cylinder 221 drives the long sliding block 222 to pull backwards, the pouring groove 223 is communicated, the thick mixture enters the extrusion box 21, at the moment, the long sliding block 222 is connected with the buckle 245 through the long groove 244 to pull the chain 243 to move backwards, the outer ring of the inner meshing ratchet wheel 241 and the second gear 242 are reversed, the inner ring of the inner meshing ratchet wheel 241 does not rotate, and the rolling wheel 23 does not move;

further, when the spring telescopic cylinder 221 is retracted to the bottom, the spring telescopic cylinder will push forward to drive the long sliding block 222 to advance, at this time, the long sliding block 222 seals the pouring trough 223, the material conveying is stopped, the long sliding block 222 is connected with the buckle 245 through the long groove 244 to pull the chain 243 to move forward, the whole inner engaged ratchet wheel 241 and the second gear 242 rotate forward, and the rolling wheel 23 rotates;

further, the long slider 222 continues to advance to press the thick mixture to the center of the two rolling wheels 23, and the rolling wheels 23 rotate in opposite directions to drive the thick mixture to go out uniformly, and roll the thick mixture into a paint film onto the parallel plates 212.

Referring to fig. 2, 6 and 7, the crushing unit 32 includes a plurality of crushing wheels 321 disposed in the crushing box 31 and intersecting with each other, a roller 322 disposed at one end of the crushing box 31 and connected to the crushing wheels 321, a belt 323 connecting all the rollers 322 at the same end, a motor cover 324 sleeved outside one roller 322, a first motor 325 disposed in the motor cover 324 and connected to the roller 322 at the execution end, a winnowing unit 33 including a second blower 331 disposed at the bottom of the crushing box 31 near one end of the crushing box 21, a screening net 332 disposed at the same position at the other end of the crushing box 31, a discharge pipe 333 disposed at the screening net 332, a driving unit 43 including a second motor 431 disposed at the top of one side of the semicircular bracket 41, a first gear 432 disposed at the execution end of the second motor 431, a thread groove 433 disposed at the middle of the outer side of the recovery wheel 42 and meshed with the first gear 432.

It should be noted that, the inner ring of the recovery wheel 42 has a groove to prevent the material from falling from the side in the recovery process, the crushing box 31 is semi-cylindrical, the upper feed opening is slightly smaller than the diameter of the inner ring of the recovery wheel 42, so that the material can fall into the crushing box 31 as much as possible when the recovery wheel 42 recovers the material, the length of the coating film extruded and discharged by the extrusion box 21 at one time is slightly smaller than the width of the groove, the coating film is sent into the recovery wheel 42 by the parallel plates 212, and two groups of crushing parts 32 are respectively positioned at two ends of the crushing box 31, so that the adjacent crushing wheels 321 mutually rotate in the direction;

further, the second motor 431 is started, the first gear 432 is meshed with the thread groove 433 to drive the recovery wheel 42 to rotate on the semicircular bracket 41, and the coating film in the recovery wheel 42 falls into the crushing box 31 under the action of gravity;

further, the first motor 325 in the motor cover 324 at both ends of the crushing box 31 is started, and the crushing wheel 321 is driven to rotate to crush the paint film by the roller 322 and the belt 323;

further, the second blower 331 is started to blow paint powder from the screening net 332 to the discharging pipe 333 for discharging, and the screened paint falls into the recovery wheel 42 for cyclic crushing.

The specific flow of the invention is as follows:

the electrical components in the invention are triggered to work by a PLC (programmable logic controller) model of which is FX3U-16 MR.

When the device starts to work, the first blower 12 is started to form strong circulating air in the heating furnace 11, thermosetting trifluorochloroethylene-vinyl ether ester, tetrafluorochloroethylene-vinyl ether and thermoplastic polyvinylidene fluoride are sequentially and quantitatively added into the heating furnace 11 according to the formula, the mixture is lifted and mixed through the circulating air, the heating furnace 11 heats the mixture, the resin raw materials are melted, the mixture thickens, then the spring telescopic cylinder 221 drives the long slide block 222 to pull backwards, the material pouring groove 223 is conducted, the thick mixture enters the extrusion box 21, at the moment, the long slide block 222 is connected with the buckle 245 through the long groove 244 to pull the chain 243 backwards, the outer ring of the internal meshing ratchet wheel 241 and the second gear 242 are reversed, the inner ring of the internal meshing ratchet wheel 241 does not rotate, the rolling wheel 23 does not move, when the spring telescopic cylinder 221 is contracted to the bottom, the long slide block 222 is pushed forwards to drive the long slide block 222 to advance, at this time, the long slide block 222 closes the pouring trough 223, stops the material feeding, the long slide block 222 is connected with the buckle 245 through the long groove 244 to pull the chain 243 to move forward, the whole of the inner meshing ratchet wheel 241 and the second gear 242 rotate forward, the rolling wheel 23 rotates, the long slide block 222 continuously moves forward, the mixture in a rolling thick state is extruded to the right center of the two rolling wheels 23, the rolling wheels 23 rotate oppositely to drive the mixture in a thick state to uniformly go out, the mixture is rolled into a coating film on the parallel plate 212, then the second motor 431 is started, the first gear 432 is meshed with the thread groove 433 to drive the recovery wheel 42 to rotate on the semicircular bracket 41, the coating film in the recovery wheel 42 falls into the crushing box 31 under the action of gravity, finally, the first motor 325 in the motor covers 324 at two ends of the crushing box 31 is started, the crushing wheel 321 is driven to rotate and crush the coating film through the rolling wheels 322 and the belt 323, the second blower 331 is started, the paint powder is blown out from the screening net 332 to the discharging pipe 333 for discharging, and the screened paint quickly falls into the recovery wheel 42 for cyclic crushing.

While the invention has been described above with reference to the accompanying drawings, it will be apparent that the invention is not limited to the embodiments described above, but is intended to be within the scope of the invention, as long as such insubstantial modifications are made by the method concepts and technical solutions of the invention, or the concepts and technical solutions of the invention are applied directly to other occasions without any modifications.

Claims (10)

1. The preparation process of the fluororesin powder coating is characterized by comprising the following steps of:

firstly, fully mixing raw materials, namely, thermosetting chlorotrifluoroethylene-vinyl ether (ester), tetrafluorochloroethylene-vinyl ether (FEVE) resin and thermoplastic polyvinylidene fluoride (PVDF) resin which are used for manufacturing a fluororesin powder coating, sequentially and quantitatively adding pigments, fillers and auxiliary agents into a mixing device (10) according to a formula, and fully mixing and heating;

step two, thermoplastic extrusion film forming, namely introducing the mixed and heated mixture into an extrusion device (20), and extruding the mixture into a coating film through extrusion and rolling;

thirdly, crushing the coating film into powder, pouring the extruded coating film into a crushing device (30), crushing the coating film extruded into powder by the crushing device (30), and discharging the small-particle qualified powdery coating by a blowing-out system of a winnowing component (33);

and step four, circularly crushing the screened objects, collecting large paint film particles which are not completely pulverized and screened out by primary crushing through a recovery device (40), and reintroducing the large paint film particles into a crushing device (30) for circularly crushing and discharging, thereby improving the yield.

2. The process for preparing the fluororesin powder coating according to claim 1, wherein the mixing device (10) comprises a heating furnace (11), a first blower (12) arranged at one end of the heating furnace (11), a pressing box (21) arranged at one end inside the pressing box (21) and used for pressing the mixture, a pushing component (22) arranged at the other end inside the pressing box (21) and used for pressing the mixture, two rolling wheels (23) arranged at the other side of the pressing box (21) and used for improving the forming quality in a vertically rotatable manner, and a linkage component (24) arranged at one side outside the pressing box (21) and used for cooperating with the pushing component (22) and the rolling wheels (23); the crushing device (30) comprises a crushing box (31), a crushing part (32) arranged in the crushing box (31), a winnowing part (33) arranged at the bottom of the crushing box (31), a recycling device (40) comprises a semicircular bracket (41), a recycling wheel (42) rotatably arranged in the semicircular bracket (41) and a driving part (43) arranged at one side of the recycling wheel (42).

3. The process for preparing the fluororesin powder coating according to claim 2, wherein the interior of the heating furnace (11) is cylindrical, and comprises a first bracket (111) provided at the top of the extrusion box (21), and a feed inlet (112) provided at the top of the heating furnace (11).

4. A process for preparing a fluororesin powder coating according to claim 3, wherein the first blower (12) comprises a support pile (121) provided at one end of the first bracket (111), the support pile (121) is provided, and the output end of the first blower (12) is inserted into the heating furnace (11) and faces obliquely downward.

5. The process for preparing the fluororesin powder coating according to claim 2, wherein the crushing member (32) comprises a plurality of crushing wheels (321) arranged in the crushing box (31) in a crossing manner, a roller (322) arranged at one end of the crushing box (31) and connected with the crushing wheels (321), a belt (323) connected with all the rollers (322) at the same end, a motor cover (324) sleeved outside one roller (322), and a first motor (325) arranged in the motor cover (324) and connected with the roller (322) at an execution end.

6. The process for preparing a fluororesin powder coating according to claim 2, wherein the air separation unit (33) comprises a second blower (331) provided at the bottom of the crushing box (31) near one end of the extrusion box (21), a screen (332) provided at the same position as the other end of the crushing box (31), and a discharge pipe (333) provided at the screen (332).

7. The process for preparing a fluororesin powder coating according to claim 2, wherein the driving means (43) comprises a second motor (431) provided at a top portion of one side of the semicircular bracket (41), a first gear (432) provided at an execution end of the second motor (431), a screw groove (433) provided at an outer middle portion of the recovery wheel (42) and engaged with the first gear (432).

8. The process for preparing a fluororesin powder coating according to claim 2, wherein the pushing member (22) comprises a plurality of spring telescopic cylinders (221) fixed at one end inside the extrusion tank (21), long sliders (222) provided at the execution ends of all the spring telescopic cylinders (221), and a pouring tank (223) provided at the top of the extrusion tank (21).

9. The process for preparing the fluororesin powder coating according to claim 2, wherein two semi-enclosed space boxes (211) are symmetrically arranged up and down inside the discharge end of the extrusion box (21), parallel plates (212) are arranged outside the discharge end of the extrusion box (21), and the rolling wheel (23) is rotatably connected in the space boxes (211).

10. The process for preparing the fluororesin powder coating according to claim 8, wherein the interlocking member (24) comprises two internally engaged ratchets (241) which are arranged on one side of the outside of the extrusion box (21) and connected with the roller (23), two second gears (242) which are arranged at the distal ends of the internally engaged ratchets (241) in parallel, a chain (243) which connects each group of internally engaged ratchets (241) and the second gears (242), two long grooves (244) which are arranged on one side of the extrusion box (21), and a buckle (245) which penetrates the long grooves (244) and connects the long sliding block (222) with the chain (243).