CN102896789B - Manufacturing method of polytetrafluoroethylene moulding, manufacturing method of polytetrafluoroethylene platelet, and polytetrafluoroethylene platelet - Google Patents
Manufacturing method of polytetrafluoroethylene moulding, manufacturing method of polytetrafluoroethylene platelet, and polytetrafluoroethylene platelet Download PDFInfo
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- CN102896789B CN102896789B CN201210262116.3A CN201210262116A CN102896789B CN 102896789 B CN102896789 B CN 102896789B CN 201210262116 A CN201210262116 A CN 201210262116A CN 102896789 B CN102896789 B CN 102896789B
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Abstract
The invention provides a manufacturing method of a polytetrafluoroethylene moulding, a manufacturing method of a polytetrafluoroethylene platelet, and the polytetrafluoroethylene platelet. By using the manufacturing methods, deformation degree can be inhibited from worsening when manufacturing time is shortened, or when the inhibited deformation degree is relatively small, the needed manufacturing time does not become longer. A cylindrical block obtained by compressing and maudlin the polytetrafluoroethylene power is heated to a temperature over a melting point and undergoes a first temperature reduction treatment, and then undergoes a second temperature reduction treatment in at a more stable speed than the first temperature reduction treatment, and then is cooled to obtain a crystallized temperature. The crystallized temperature of the block is the temperature that the crystallization of the block ends.
Description
Technical field
The present invention relates to the manufacture method of polytetrafluoroethylmolding molding, the manufacture method of polytetrafluoroethylene (PTFE) sheet thing and polytetrafluoroethylene (PTFE) sheet thing
Background technology
The viscosity of polytetrafluoroethylene (PTFE) (hereinafter referred to as PTFE) is high, and its melt viscosity is about 10 at 380 DEG C
11pool, (melt viscosity time shaping is 10 to be difficult to use general thermoplastic resin
3~ 10
4pool) forming method such as extrusion molding, injection moulding that adopts is shaping.
Therefore, as the forming method of PTFE, such as, as described in patent document 1 (International Publication No. 98/041386 publication), compression forming is the most general method.Particularly, as the forming method of PTFE molded product in block form (being commonly called large block), employing be the method for compression forming.
In compression forming, carry out according to following (a) ~ (c) operation.
A () fills material powder in a mold equably, at normal temperatures, use pressure apparatus with 100 ~ 1000kg/cm
2pressure compresses.
B the more crisp unfired body obtained is put into stove by (), be warming up to 360 ~ 380 DEG C, to make it hot sticky, keeps this temperature until sintering completes equably comprehensively.
C the temperature of stove is directly cooled to room temperature by (), obtain molded product in block form.
The molded product in block form so obtained is cut, obtains the film that thickness is such as about 25 μm.The PTFE film obtained is as the use such as thermal insulation tape of heatproof wire, vehicle motor/generator etc.
Therefore, according to the record of above-mentioned patent document 1 (International Publication No. 98/041386 publication), in existing method for cooking, the weight due to himself makes molded product in block form after firing remain internal stress.So produce warpage and deforming at molded product in block form when firing, therefore, problem is had in mind and is being cut film that molded product in block form obtains and occur the loss etc. of curling (wrinkle, bend, distortion etc.) and the easy PTFE material that generation price is high.Therefore, in order to address these problems, propose following method for cooking, wherein, first form the unfired body of PTFE, rotate while fire this unfired body in stove.
Summary of the invention
[inventing problem to be solved]
According to the method for cooking recorded in above-mentioned patent document 1 (International Publication No. 98/041386 publication), distortion and the residual stress of obtained molded product in block form can be reduced.But, in the refrigerating work procedure of the molded product in block form after firing in this method for cooking, but be propose to be cooled to room temperature monotonously by leaving standstill, or use specific cooling device to cool monotonously until target temperature.So, it does not carry out detailed research for the issuable distortion in place such as molded product in block form inside in refrigerating work procedure and residual stress at all.
Particularly, PTFE pyroconductivity very low, so in refrigerating work procedure, even if the surface temperature of molded product in block form reduces sometimes, but internal temperature not image surface temperature reduces like that, creates large temperature difference between surface temperature and internal temperature, remain large distortion on the contrary.The thickness of molded product in block form is larger, and the temperature difference of surface temperature and internal temperature more easily becomes greatly, and thus such distortion becomes more remarkable.Therefore, in the refrigerating work procedure of molded product in block form, in order to issuable distortion is suppressed to less, needs to utilize time enough little by little cooling, increase to make the temperature difference not causing surface temperature and internal temperature.
On the other hand, existing refrigerating work procedure reduces in the cooling means of temperature like that monotonously, if want the temperature difference maintaining surface temperature and internal temperature large unlike the temperature difference of regulation during cooling, then needs the time grown very much.
Thus, according to do not make as far as possible the temperature difference of surface temperature and internal temperature increase while the time shortened as much as possible required for cooling determine be out of shape degree and manufacture required for time between balance, and cool, obtain the polytetrafluoroethylmolding molding of the balance specified.
But, for the polytetrafluoroethylmolding molding of the balance of such regulation, want the words shortening the time required for manufacturing further, the degree of being then out of shape will worsen, or want further the degree of distortion to be suppressed less, then the time manufacturing needs will be elongated further.
The present invention has put in view of above-mentioned this, the object of the present invention is to provide the manufacture method of the manufacture method of the polytetrafluoroethylmolding molding of any one object that can realize in following object, a kind of polytetrafluoroethylene (PTFE) sheet thing, a kind of polytetrafluoroethylene (PTFE) sheet thing, described object suppresses distortion while shortening the time required for manufacturing, distortion being suppressed less or shortens the time required for manufacturing.
[solving the means of problem]
The manufacture method of the polytetrafluoroethylmolding molding that the 1st viewpoint of the present invention relates to is as follows: cylindric blocks polytetrafluorethylepowder powder compression forming obtained, be heated to until after exceeding the temperature (fusion temperature) of fusing point, carry out the 1st cooling process, after 1st cooling process, carry out the 2nd cooling process, with than the stable cooling rate of described 1st cooling process, be cooled to crystallized temperature.Described crystallized temperature is following temperature: for the PTFE of the object blocks of formation the 1st cooling process, making DSC (Differential Scanning Calorimetry, differential scanning calorimetric analysis) curve when, described crystallized temperature is the temperature on exothermal peak summit, and it take JIS-K7121 as the temperature that standard test obtains.
In addition, after the 1st cooling process stops, the 2nd cooling process start before during, only otherwise violate purport of the present invention, also can carry out other Temperature Treatment.Such as, also when the 1st cooling process stops, process temperature now being maintained the very short time can be carried out, starts thereafter the 2nd cooling process.
The manufacture method of the polytetrafluoroethylmolding molding that the manufacture method of the polytetrafluoroethylmolding molding that the present invention the 2nd viewpoint relates to relates to as the 1st viewpoint, wherein, the state that the 1st cooling process only produces the temperature range of crystallization high in the surface temperature of blocks or the atmosphere temperature of blocks are than blocks is carried out.
The manufacture method of the polytetrafluoroethylmolding molding that the 3rd viewpoint of the present invention relates to is the manufacture method of the polytetrafluoroethylmolding molding related to as the 2nd viewpoint, wherein, after the surface temperature of blocks or the atmosphere temperature of blocks are cooled to crystallized temperature, during the stipulated time, the surface temperature of blocks or the atmosphere temperature of blocks are maintained crystallized temperature.
Herein, for " during the stipulated time ", such as, can using until the temperature difference of blocks internal temperature and surface temperature become enough little this section during as " during the stipulated time ".For described " temperature difference becomes enough little ", such as, the temperature difference of the blocks internal temperature of stipulated time and surface temperature can be reached less than 50%, less than 40%, less than 30%, less than 20% or less than 10% of the temperature difference of start time to be seen as " temperature difference becomes enough little ".
The polytetrafluoroethylmolding molding that the present invention the 4th viewpoint relates to is that the manufacture method manufacture of the polytetrafluoroethylmolding molding that in use the 1st viewpoint to the 3rd viewpoint, arbitrary viewpoint relates to obtains.
For the manufacture method of the polytetrafluoroethylene (PTFE) sheet thing that the present invention the 5th viewpoint relates to, its be in use the 1st viewpoint to the 3rd viewpoint arbitrary viewpoint relate to the products formed that obtains of the manufacture method of polytetrafluoroethylmolding molding carry out cutting to manufacture polytetrafluoroethylene (PTFE) sheet thing
The polytetrafluoroethylene (PTFE) sheet thing that the present invention the 6th viewpoint relates to is the polytetrafluoroethylene (PTFE) sheet thing that the manufacture method of the polytetrafluoroethylene (PTFE) sheet thing using the present invention the 5th viewpoint to relate to obtains.
[effect of invention]
According to the present invention, when manufacturing polytetrafluoroethylmolding molding, even if when the time required for manufacturing shortens, also the deterioration of deformation extent can be suppressed, or, even if when deformation extent deterioration is suppressed in less, the time required for manufacture also can not be increased.
Accompanying drawing explanation
[Fig. 1] is the curve map of the time variations of the atmosphere temperature representing blocks of the present invention.
[Fig. 2] is the stereogram of the example representing blocks shape.
[Fig. 3] is the frame-shaped pie graph of the example representing in-furnace temperature control system.
[Fig. 4] is the side cross-sectional sketch of the example representing stove.
[Fig. 5] is the side cross-sectional sketch of other examples representing stove.
[Fig. 6] is the curve map representing DSC curve.
[Fig. 7] represents the curve map of the time variations overview of supply hot blast temperature.
[Fig. 8] represents the curve map of the time variations overview of blocks internal temperature and surface temperature temperature difference.
[Fig. 9] is the cross-sectional perspective view of stove and the blocks used in embodiment and reference example.
[Figure 10] is the curve map of the time variations of the supply hot blast temperature represented in reference example 1, blocks surface temperature and blocks internal temperature.
[Figure 11] represents the blocks surface temperature of embodiment 1, reference example 1 and the time changing curve figure of blocks internal temperature.
[Figure 12] is the curve map of the time variations representing the blocks surface temperature of embodiment 1, reference example 1 and the temperature difference of internal temperature.
Detailed description of the invention
The manufacture method of polytetrafluoroethylene (PTFE) of the present invention (hereinafter referred to as " PTFE ") products formed is as follows: cylindric blocks polytetrafluorethylepowder powder compression forming obtained, after being heated to exceed the temperature of fusing point, carry out the 1st cooling process, after 1st cooling process, with than the stable cooling rate of the 1st cooling process, carry out the 2nd cooling process, be cooled to the crystallized temperature of blocks, obtain PTFE products formed thus, the crystallized temperature of described blocks is the temperature that blocks crystallization terminates.Such as, an example as shown in the plot of figure 1 like that, changes the temperature of the hot blast to blocks supply, can obtain PTFE products formed thus by the order between calefactive interzone, hot sticky interval, crystallization interval, cooling zone.
Further, the manufacture method of being cut by the PTFE products formed obtained this manufacture method can manufacture polytetrafluoroethylene (PTFE) sheet thing.To the purposes of this polytetrafluoroethylene (PTFE) sheet thing without special restriction, such as, liner, sealing gasket, packing ring, diaphragm valve etc. can be enumerated.Such as, under obtaining the film situation of thickness about 25 μm, can as uses such as the thermal insulation tapes of heatproof wire, vehicle motor/generator etc.
(PTFE powder)
The powder that PTFE powder obtains preferably through suspension polymerisation, but also can be the powder obtained by other polymerization (such as emulsion polymerisation).To the average grain diameter of polytetrafluorethylepowder powder without special restriction, it can be 10 μm ~ 1000 μm.
As PTFE, be difficult to carry out shaping PTFE by the forming method such as extrusion molding, injection moulding and can enumerate the homopolymers of such as PTFE or the copolymer of tetrafluoroethene and other fluorochemical monomer.In this copolymer, the mol ratio of tetrafluoroethene and fluorochemical monomer is preferably 95:5 ~ 99.999:0.001.And, the copolymer (i.e. the polytetrafluoroethylene (PTFE) of vinyl ethers modification) that this copolymer is preferably made up of tetrafluoroethene and perfluoroalkyl vinyl ether.
Perfluoroalkyl vinyl ether is preferably with formula (I): CF
2=CF-OR
fthe compound represented.
[R
fbe organic group, it must have carbon atom and fluorine atom, without hydrogen atom, but can have oxygen atom]
R in the perfluoroalkyl vinyl ether of formula (I)
fat least one group in group shown in base is preferably perfluoroalkyl that carbon number is 1 ~ 10, carbon number is 4 ~ 9 perfluor (alkoxyalkyl) base, the group shown in formula (II) and formula (III).Formula (II):
[in formula (II), m is the number of 0 ~ 4]
Formula (III)
[in formula (III), n is the number of 1 ~ 4]
(blocks of drum)
Such as, as long as the drum that polytetrafluorethylepowder powder compression forming obtains by blocks then limits without special, also can be the blocks 10 of the shape had as shown in the stereogram of Fig. 2.Described blocks is not limited to proper drum, and it can be generally with the shape of circle, and also can make is the shape after drum is out of shape a little.And as blocks shape, it can be the shape that axial length diameter group is long, it also can be the short shape of axial length diameter group.As in Fig. 2 with shown in " S ", the maximum gauge of blocks refers to the radial distance between the outer surface 10a of blocks 10 and inner surface 10b, and to it, there is no particular limitation, be preferably 5cm ~ 50cm, be particularly preferably 10cm ~ 30cm.
(compression forming)
Compression pressure during compression forming can be 100kg/cm
2~ 1000kg/cm
2.The time that compression pressure keeps can be 1 minute ~ 5 hours.
(calefactive interzone)
Calefactive interzone is not particularly limited, such as, blocks compression forming obtained puts into stove, atmosphere temperature is heated up, arrive the interval before intensification target temperature, described intensification target temperature more than the fusing point (fusion temperature) of PTFE temperature and be less than the temperature that PTFE occurs to decompose.Described intensification target temperature is higher than the ceiling temperature of crystallized temperature scope described later.It should be noted that, about the fusing point (fusion temperature) of described PTFE, for the PTFE forming object blocks, when having made DSC curve, it is the temperature on endothermic peak summit, is take JIS-K7121 as the temperature that standard test obtains.Particularly, herein, for the PTFE forming object blocks, when having made DSC curve, using the fusing point of following temperature as common PTFE: be heated to above the temperature temperature of fusing point (when expression is fired) observing endotherm peak temperature at first, thereafter first make temperature reduce and observe exothermal peak (temperature of exothermal peak represents crystallized temperature), thereafter it is again made to heat up, when second time observes endothermic peak, using the fusing point of the temperature of this endothermic peak as usual PTFE.
For programming rate herein, in order to avoid blocks surface and inner temperature difference become excessive, preferably consider that the heat conducting speed of PTFE inside and the thickness etc. of maximum gauge part are suitably determined.
(hot sticky interval)
Hot sticky interval is the interval after making the atmosphere temperature in stove rise to intensification target temperature in calefactive interzone, and it is holding temperature interval of carrying out process identical with intensification target temperature before the sintering of blocks completes comprehensively uniformly.It should be noted that, from the view point of the uniformity improving the hot sticky state of PTFE powder, described hot sticky interval preferably maintains 1 ~ 100 hour, preferably maintain 10 ~ 50 hours further, but when the uniformity of the hot sticky state of the end time PTFE powder of calefactive interzone is fully guaranteed, also hot sticky interval can be shortened.
As the system of heat supply device with such stove, such as, in-furnace temperature control system 100 as shown in Figure 3 can be enumerated.This in-furnace temperature control system 100 possesses holds the stove 20 of PTFE blocks 10 and the heat supply device 30 for adjusting the temperature in stove 20 therein.The control part 34 that heat supply device 30 possesses the heating part 32 producing the heat sent in stove 2, the air supplying part 33 sent into for the heat produced by heating part 32 in stove 20, the in-furnace temperature sensor 31 being used for the temperature (being specifically, heated by heating part 32 and the temperature of the air sent into by air supplying part 33) grasped in stove 20, the information that obtains based on in-furnace temperature sensor 31 control the power output of heating part 32 and air supplying part 33.Control power output (such as reduce temperature with the power output reducing heating part 32 and/or reduce supply heat with the power output reducing air supplying part 33 thus reduce temperature etc.) by the control part 34 of this heat supply device 30, regulate the variations in temperature of blocks 10 thus.The power output level that can be configured to heating part 32 and air supplying part 33 can regulate continuously, and the power output level that also can be configured to heating part 32 and air supplying part 33 can regulate in classification.And the flow velocity produced for described air supplying part 33 is without special restriction, and from the view point of the efficiency fired, this flow velocity is preferably 1m/s ~ 10m/s, is more preferably 2m/s ~ 5m/s.It should be noted that, described in-furnace temperature control system 100 provides as the example of device controlling block temperature, and the device controlling block temperature is not limited in this.
As the stove for heating blocks, it also can be the rotary heating formula stove carrying out heating making heated material rotate while.As using firing of such rotary heating formula stove, can carry out as shown in Figure 4, roller 21a is arranged on the inner side of blocks 10, makes roller 21a rotate and make blocks 10 with rotating shaft 10c for axle center rotates, while make to heat up in stove 20 to fire; Wherein, described roller 21a rotates this blocks 10 in the horizontal direction for the axis that remain the blocks 10 of PTFE.And, as other examples fired of the stove of use rotary heating formula, can fire as shown in Figure 5, wherein, be provided with in stove 20 for the blocks 10 of PTFE being contained in inside and the cylindrical body 21d making it rotate, being used for roller 21b, 21c of making described cylindrical body 21d rotate, along with the rotation of these rollers 21b, 21c, cylindrical body 21d rotated, make blocks 10 rotate thus, make to heat up in stove 20 to fire while making blocks 10 rotate.It should be noted that, blocks 10 continuous rotation can be made, blocks 10 also can be made to rotate off and on.Rotary speed can be 1 ~ 300 turn/hour usually.So, making it heat up by making the blocks putting into stove rotate, the uniformity of obtained fired body can be improved thus.
Blocks after the process in calefactive interzone and hot sticky interval terminates, transfers to crystallization interval.Interval at described crystallization, use above-mentioned stove and heat supply device etc., carry out the 1st cooling process and the 2nd cooling process.
(the 1st cooling process in crystallization interval)
Blocks after terminating for the process in calefactive interzone and hot sticky interval, implements the 1st cooling and processes starting the more Zao moment than the 2nd cooling process described later.Described 1st cooling process is the process temperature of blocks being reduced to process cooling rate faster than the 2nd cooling.Such as, also can carry out cooling as follows to control, wherein, carry out the power output of the heat supply device of the 1st cooling process decrease fast stove of blocks, thereafter, the 2nd cooling process weakens the heat supply device of stove power output with stable speed is carried out.
Preferably from following state cooling rate than the 2nd cooling process the 1st cooling process faster: for the surface temperature of blocks, hot sticky interval is terminated and surface reaches intensification target temperature or surface slightly lower than the state of intensification target temperature; Or the atmosphere temperature of blocks reaches intensification target temperature or slightly lower than the state of intensification target temperature.And, before the surface temperature of blocks or the atmosphere temperature of blocks are reduced to lower than intensification target temperature and higher than crystallized temperature range limit temperature temperature, preferably terminate described 1st cooling process.Preferably do not carry out described 1st cooling process in the surface temperature of blocks or the atmosphere temperature of blocks lower than the state of the temperature under crystallized temperature range limit temperature.
For the PTFE formed as the blocks of the 1st cooling handling object, as shown in the curve map of Fig. 6, temperature (DEG C) is got at transverse axis, the longitudinal axis gets energy (mW), when making DSC curve, DSC curve demonstrates the changing condition of energy relative to temperature, now, described crystallized temperature in the present invention is the temperature (temperature represented by " Tc " in Fig. 6) on exothermal peak summit, and the described crystallized temperature in the present invention take JIS-K7121 as the temperature that standard test obtains.
In addition, in the curve map of Fig. 6, crystallized temperature scope is defined as by more than the specific lower limit temperature of DSC curve (in Fig. 6 " Tl " institute temp. displaying function) and ceiling temperature (in Fig. 6 " Th " institute temp. displaying function) temperature range below.The lower limit temperature of crystallized temperature scope is decided to be following temperature: the tangent line (tX) that curve map starts lifting position at baseline (BLL) low temperature side and the temperature of the intersection point of tangent line (tL) of drawing in the maximum point of peak crystallization low temperature side slope.The ceiling temperature of crystallized temperature scope is decided to be following temperature: the tangent line (tY) that curve map starts lifting position at baseline (BLH) high temperature side and the temperature of the intersection point of tangent line (tH) of drawing in the maximum point of peak crystallization high temperature side negative slope.
It should be noted that, above-mentioned DSC condition determination is as follows: programming rate: 10 DEG C/min, and under air atmosphere, sample size: 3.000mg, primary standard substance be air.
It should be noted that, the cooling rate carried out during the 1st cooling process can be fixing, also can be change.And, during carrying out the 1st cooling process when changing cooling rate, such as, can adjust than cooling rate slow (reposefully) the slowest during carrying out the 1st cooling process according to cooling rate the fastest during carrying out the 2nd cooling process.And, such as, also can adjust more greatly than the cooling rate during implementation the 2nd cooling process according to the average cooling rate during implementation the 1st cooling process.
(the 2nd cooling process in crystallization interval)
2nd cooling process is carried out to the blocks that the 1st cooling process terminates, to make blocks temperature slowly reduce than the stable cooling rate of the 1st cooling process.
As long as implement after the 1st cooling process, to beginning opportunity of the 2nd cooling process without special restriction, such as, can start after the 1st cooling process just terminates, start after also can having carried out other process after the 1st cooling process terminates.When the atmosphere temperature of surface temperature or blocks that the beginning of the 2nd cooling process is preferably blocks opportunity occurs on the ceiling temperature of the crystallized temperature scope of crystallization in blocks.
The atmosphere temperature that 2nd cooling process preferably proceeds to in-furnace temperature or blocks surface temperature or blocks reaches crystallized temperature.Herein, carry out the cooling rate during the 2nd cooling process, can be fixing, may also be change.When changing cooling rate during carrying out the 2nd cooling process, can adjust according to the average cooling rate of carrying out during the 2nd cooling process is less than the cooling rate of carrying out during the 1st cooling process.
In addition, after the surface temperature of in-furnace temperature or blocks or the atmosphere temperature of blocks drop to crystallized temperature, during the stipulated time, the surface temperature of in-furnace temperature or blocks or the atmosphere temperature of blocks is preferably made to maintain crystallized temperature.Like this, by the surface temperature of blocks or the atmosphere temperature of blocks are maintained crystallized temperature during the stipulated time, the surface of blocks not only can be made to be in state of temperature close to crystallized temperature, inside for blocks also can make it reach state of temperature close to crystallized temperature, thus the distortion of obtained PTFE products formed can be suppressed little.
(between cooling zone)
For the blocks that the 2nd cooling process terminates, under being positioned over normal temperature, or positive supply is cold and hot, is cooled by blocks thus., because the temperature of blocks is lower than crystallized temperature, not easily blocks inner homogeneous is had an impact herein, so, in order to shorten the time, preferably with the cooling rate faster than the cooling velocity in the 2nd cooling process, reduce the temperature of blocks.Or, also can be down to after under the lower limit temperature (" Tl " institute temp. displaying function in Fig. 6) of the crystallized temperature scope lower than crystallized temperature, improve cooling rate.For these process, can go out send from the angle of productivity ratio and required physical property etc. and suitably select.
(the combination example of the 1st cooling process and the 2nd cooling process)
Give the time variations of the temperature when the hot blast provided with heat supply device carries out heat control in Fig. 7, wherein list the combination example of the 1st cooling process and the 2nd cooling process, and example when cooling processing speed is fixed.It should be noted that, the atmosphere temperature of what in Fig. 7, the value of the curve map longitudinal axis represented the is not blocks of PTFE, but carry out the temperature of the control objectives value controlled as in-furnace temperature control system.
No matter at any example, what provide is all after calefactive interzone and hot sticky interval stop, from the state of specified temp (in the figure 7 the hot blast temperature of supply shown in " Ts "), the example under making its temperature be reduced to crystallized temperature (in the figure 7 " Tc " institute temp. displaying function) situation.
In the figure 7, " X " shown in solid line is the example of following situation: so that supply hot blast temperature is dropped to crystallized temperature as target, do not distinguish the 1st cooling process and the 2nd cooling process, at this therebetween with fixing cooling rate, the state after making reduction supply the temperature of hot blast, supply hot blast temperature being maintained at crystallized temperature continues the stipulated time.In the example of described " X ", make supply hot blast temperature be reduced to time required for temperature of the ceiling temperature of crystallized temperature scope long, be difficult to rapid manufacture.
" A " that represent with solid line is in the figure 7 following situation: to make, supply hot blast temperature is higher than the ceiling temperature of crystallized temperature scope carries out the 1st cooling process as target, then the 2nd cooling process is carried out, in 2nd cooling process, being down to time same with above-mentioned " X " example time required for crystallized temperature with from initial state (state of temperature of " Ts ") to making supply hot blast temperature, reducing supply hot blast temperature lentamente.In this " A " example, under the state that blocks surface temperature is higher than the ceiling temperature of crystallized temperature scope, cooling is carried out rapidly, obtain the effect of shortening time thus, simultaneously, under the state that blocks surface temperature becomes the temperature lower than the ceiling temperature of crystallized temperature scope, because cooling rate becomes steadily (negative slope of curve map is little), so the surface of blocks and inner temperature difference can be suppressed to less.So, due to this cooling that blocks surface can be suppressed less with inner temperature difference can be carried out, so can make having good uniformity of obtained blocks at the gamut of crystallized temperature.
" B " that represent with thick dotted line is in the figure 7 the example of following situation: to make, the temperature of supply hot blast is higher than the ceiling temperature of crystallized temperature scope carries out the 1st cooling process as target, then the 2nd cooling process is carried out, with the thermograde with " X " example same degree, supply hot blast temperature is down to crystallized temperature.In the example of described " B ", under the state of temperature that the surface temperature of blocks is higher than the ceiling temperature of crystallized temperature scope, cooling is carried out rapidly, obtain the effect of shortening time thus, meanwhile, becoming the state of temperature lower than the ceiling temperature of crystallized temperature scope in blocks surface temperature, is also the cooling rate same with " X " example, therefore, blocks surface also can be identical with the degree of " X " example with inner temperature difference.In the example of described " B ", same in the cooling rate between the ceiling temperature of crystallized temperature and crystallized temperature scope and " X ", but compared with " X ", the time of the temperature of supply hot blast to be down to required for crystallized temperature can be shortened.Therefore, thereafter, the process temperature of supply hot blast being maintained crystallized temperature can be extended, or, transfer between cooling zone in the stage more early.
" C " shown in single dotted broken line is used to be the example of following situation in the figure 7: the temperature of supply hot blast to be reduced to higher than the ceiling temperature of crystallized temperature scope and lowlyer than the example of " A " to carry out the 1st cooling for target and process, then the 2nd cooling process is carried out, in 2nd cooling process, be reduced to the time same in the example of time required for crystallized temperature and above-mentioned " X " with from initial state (state of temperature of " Tc ") to by supply hot blast temperature, reduce supply hot blast temperature lentamente.In the example of described " C ", in blocks surface temperature under the state of temperature higher than crystallized temperature range limit temperature, cooling is carried out rapidly, obtained the effect of shortening time thus more, simultaneously, the state of temperature lower than the ceiling temperature of crystallized temperature scope is become in blocks surface temperature, because cooling rate becomes more steadily (less than the negative slope of the example curve figure of " A " and " B "), so further blocks surface and inner temperature difference can be suppressed less.Like this, owing to carrying out at the temperature below crystallized temperature range limit temperature thisly the surface of blocks and inner temperature difference to be suppressed less cooling, further so the uniformity of obtained blocks can be made to become good further.
" D " shown in double dot dash line is used to be the example of following situation in the figure 7: in the scope that the temperature of supply hot blast is higher than crystallized temperature range limit temperature, with more steady than the example of " A " " B " " C ", but negative gradient more sharp-pointed compared with the example of " X ", carry out the 1st cooling process, then the 2nd cooling process is carried out, in 2nd cooling process, with the time that the example being reduced to time required for crystallized temperature and above-mentioned " X " from initial state (state of temperature of " Ts ") to supply hot blast temperature is same, reduce supply hot blast temperature lentamente.In the example of described " D ", under the state of temperature that blocks surface temperature is higher than crystallized temperature range limit temperature, cooling is carried out rapidly, obtain the effect of shortening time thus to a certain extent, simultaneously, become the state of temperature lower than the ceiling temperature of crystallized temperature scope in blocks surface temperature, cooling rate does not become the more sharp-pointed negative gradient of that degree of example as " X ", blocks surface and inner temperature difference can be suppressed less.
The example of following situation in the figure 7 with " E " that choice refreshments line represents: in the scope that warm-air supply temperature is higher than the ceiling temperature of crystallized temperature scope, to carry out the cooling (carrying out other process beyond the 1st cooling process and the 2nd cooling process) of few time than the stable negative gradient of the example of " X ", thereafter, the 1st cooling process is carried out with the negative gradient steeper than the example of " X ", then the 2nd cooling process is carried out, in 2nd cooling process, with the time that the time of being down to from initial state (state of temperature of " Ts ") to supply hot blast temperature required for crystallized temperature is same with the example of above-mentioned " X ", reduce the temperature of supply hot blast at leisure.In the example of described " E ", in blocks surface temperature under the state of temperature higher than crystallized temperature ceiling temperature, initial temperature declines with stable speed, but thereafter, temperature is able to fast speed and declines, obtain the effect of shortening time thus to a certain extent, simultaneously, under the state of temperature that blocks surface temperature becomes lower than the ceiling temperature of crystallized temperature scope, cooling rate does not become the steep negative gradient of that degree in the example as " X ", blocks surface and inner temperature difference can be suppressed less.
In fig. 8, the curve map of the time variations of the temperature difference of blocks internal temperature and surface temperature in the example of " X " and the example of " A " is given.
It should be noted that, such as, described blocks internal temperature refers to following temperature.As shown in Figure 2, apart from the temperature of position of the following length of axle of blocks on direction, footpath, the length that the described length radius length " rb " that to be the radius length " ra " of the outer surface part of cylindric blocks add upper inner surface with the half (ra-rb)/2 of the difference of the radius length " rb " of inner surface portion obtains.Namely described blocks internal temperature is the temperature in centre position radial in caliper portion.In addition, the surface temperature of described blocks is the outer surface part of columned blocks and the temperature of inner surface portion.Therefore, the difference of blocks internal temperature and surface temperature refers to the difference between these temperature.
In fig. 8, in the example of " X ", along with the process of time, the temperature difference of blocks surface temperature and internal temperature becomes large, and after the moment below the ceiling temperature that blocks surface temperature reaches crystallized temperature scope, temperature difference reaches maximum.Relative to this, in the example of " A ", carry out in the stage of the 1st cooling process, although the example of temperature difference ratio " X " is large, but because the temperature difference under this state that to be the surface temperature of blocks higher than the ceiling temperature of crystallized temperature scope, so not easily have an impact to the uniformity of obtained blocks; In the stage of carrying out the 2nd cooling process, temperature difference also after the moment below the ceiling temperature that the surface temperature of blocks reaches crystallized temperature scope, can be made at the latest to become less than the example of " X ".
It should be noted that, in the example (eliminating diagram in Fig. 8) of " C ", because strengthen cooling rate in the stage of carrying out the 1st cooling process, temperature difference is made to become larger than the example of " X " and " A ", but the example of " A " is same, not easily has an impact to the uniformity of obtained blocks; In the stage of carrying out the 2nd cooling process, also the example of temperature difference ratio " X " can be made at the latest after blocks surface temperature reaches the moment of below crystallized temperature range limit little, and because increase the cooling rate in the 1st cooling process, thus can reduce the cooling rate in the 2nd cooling process further, can make obtain the homogeneous body of blocks improves further.Thus, by improving uniformity, can the distortion of blocks inside be suppressed little.
It should be noted that, the cutter of the prolongation parallel with axis compresses on the outer surface by the blocks obtained for way described above, makes it rotate and cuts blocks, can obtain PTFE tablet thus.Thus, can obtain from internal modification is suppressed the PTFE tablet that little blocks obtains homogeneous.
[embodiment]
Enumerate embodiment and reference example below, further describe the present invention, but these examples do not form restriction to the present invention.
First, content general in embodiment and reference example is described.
PTFE powder uses " POLYFLON M-18 " (registration mark, Daikin Ind Ltd manufactures).And, utilize DSC to measure, determine the crystallized temperature Tc of this PTFE and the ceiling temperature Th of crystallized temperature scope.
Blocks is that the above-mentioned PTFE powder of uniform filling also utilizes pressure apparatus with 200kg/cm at normal temperatures in a mold
2compression obtains, and it adopts the shape of internal diameter 220mm, external diameter 630mm, height 1090mm.
As shown in Figure 9, blocks 10 as above-mentioned unfired body is put into cylindrical body 21d, and be arranged in stove 20, while cylindrical body 21d being rotated with the rotary speed of about 1rpm, with the flow velocity of 2m/s to the blocks 10 sustainable supply hot blast in cylindrical body 21d, entirety is fired uniformly.It should be noted that, in the present embodiment, use two ends to be provided with the cylindrical body 21d of circular open.
The measurement result of the time variations of the supply hot blast temperature (atmosphere temperature of blocks) of reference example 1, the surface temperature of blocks and the internal temperature of blocks as shown in Figure 10.In Fig. 10, dotted line represents warm-air supply temperature, and the thick line with zero mark represents the internal temperature of blocks, and the fine rule with zero mark represents the surface temperature of blocks.In calefactive interzone, supply hot blast temperature is warmed up to more than fusing point off and on and less than the temperature of decomposition temperature, thereafter, transfer to crystallization interval, after carrying out the process of reduction supply hot blast temperature, transfer between cooling zone, obtain the blocks being cooled to normal temperature.Herein, in the crystallization interval of reference example 1, carried out constant speed cooling process with about 40 hours at first, make the temperature of supply hot blast be down to crystallized temperature with fixing cooling rate; Then, carried out crystallized temperature and maintained process, the temperature of supply hot blast is maintained crystallized temperature by (about 20 hours) at the appointed time.Thereafter, in cooling zone, carry out the process of quick refrigeration, be cooled to normal temperature.
In fig. 11, sets forth the measurement result of the time variations of the surface temperature of blocks and the internal temperature of blocks in reference example 1 and embodiment 1.And, in fig. 12, give the time variations of corresponding reference example 1, the blocks internal temperature of embodiment 1 and the temperature difference of surface temperature.
Reference example 1 be constant speed cooling process in 40 hours consuming time, when crystallized temperature maintain process in 20 hours consuming time example.
In embodiment 1, do not carry out the constant speed cooling process carried out in reference example 1, the substitute is, carry out the 1st cooling process and the 2nd cooling process.Embodiment 1 carries out the example (being equivalent to the line represented with " 0_40_20hr " in Figure 11,12) that the 2nd cooling processes, crystallized temperature maintains the situation of process after carrying out the 1st cooling process; Wherein, in the 1st cooling process, instantaneously the temperature of supply hot blast is reduced by 10 DEG C; In 2nd cooling process, within 40 hours consuming time, temperature is made to be reduced to crystallized temperature; Crystallized temperature maintains process and carries out 20 hours.
Within the scope of crystallized temperature, the surface temperature of preferred blocks and the temperature difference of internal temperature little as much as possible.Therefore, road as can be known from Fig. 12, in embodiment 1, the maximum temperature difference of the surface temperature of blocks in crystallized temperature scope and internal temperature can be suppressed less than the maximum temperature difference of reference example 1.Therefore, compared with the PTFE tablet obtained with the blocks of machining reference example 1, the PTFE tablet homogeneous more that the blocks of machining embodiment 1 obtains, internal modification is littlely suppressed.
[explanation of symbol]
10 blocks
20 stoves
100 in-furnace temperature control systems
[prior art document]
[patent document]
[patent document 1] International Publication No. 98/041386 publication
Claims (5)
1. the manufacture method of a polytetrafluoroethylmolding molding, it is characterized in that, the cylindric blocks that polytetrafluorethylepowder powder compression forming is obtained, be heated to until after exceeding the temperature of fusing point, carry out the 1st cooling process, the 2nd cooling process is carried out after described 1st cooling process, in described 2nd cooling process, to process stable cooling rate than described 1st cooling, be cooled to crystallized temperature, described crystallized temperature is the temperature to exothermal peak summit when described blocks making DSC curve, after being cooled to the atmosphere temperature of the surface temperature of described blocks or described blocks to reach described crystallized temperature, during the stipulated time, the atmosphere temperature of the surface temperature of described blocks or described blocks is maintained described crystallized temperature.
2. the manufacture method of polytetrafluoroethylmolding molding as described in claim 1, it is characterized in that, carry out under the state that the crystallized temperature scope that described 1st cooling process only produces crystallization in the surface temperature of described blocks or the atmosphere temperature of described blocks are than described blocks is high.
3. a polytetrafluoroethylmolding molding, it uses to obtain from the method described in claim 1 or 2.
4. a manufacture method for polytetrafluoroethylene (PTFE) sheet thing, is characterized in that, carries out cutting to manufacture polytetrafluoroethylene (PTFE) sheet thing to using the products formed obtained with method described in claim 1 or 2.
5. a polytetrafluoroethylene (PTFE) sheet thing, it uses the method described in claim 4 to obtain.
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| JP2011163676A JP5782897B2 (en) | 2011-07-26 | 2011-07-26 | Method for producing polytetrafluoroethylene molded product, method for producing polytetrafluoroethylene sheet |
| JP2011-163676 | 2011-07-26 |
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| JPS61293830A (en) * | 1985-06-21 | 1986-12-24 | Nippon Valqua Ind Ltd | Manufacture of polytetrafluoroethylene porous film |
| JP3221074B2 (en) * | 1992-06-23 | 2001-10-22 | 住友電気工業株式会社 | Method for producing continuous molded article of high crystallinity polytetrafluoroethylene |
| EP0970799B2 (en) * | 1997-03-19 | 2010-09-08 | Daikin Industries, Ltd. | method of production of a molded polytetrafluoroethylene article |
| CN1240766C (en) * | 2003-01-14 | 2006-02-08 | 广州机械科学研究院 | Filling up Teflon friction ring and its preparing method |
| CN1251858C (en) * | 2004-05-13 | 2006-04-19 | 上海市塑料研究所 | Method for preparing polytetrafluoroethylene plate for aeroengine capable of recovering original size when heated |
| CN101056902A (en) * | 2004-11-30 | 2007-10-17 | 大金工业株式会社 | Modified polytetrafluoroethylene molded article and process for manufacture thereof |
| JP5008850B2 (en) * | 2005-09-15 | 2012-08-22 | 住友電工ファインポリマー株式会社 | Tetrafluoroethylene resin molded body, stretched tetrafluoroethylene resin molded body, manufacturing method thereof, composite, filter, impact deformation absorbing material, and sealing material |
| CN101130277A (en) * | 2006-08-22 | 2008-02-27 | 沈阳气体压缩机股份有限公司 | Sintering process for filling polytetrafluoroethylene |
| TW200838681A (en) * | 2006-12-04 | 2008-10-01 | Daikin Ind Ltd | Polytetrafluoroethylene molded body and method for producing the same |
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| JP2013027983A (en) | 2013-02-07 |
| CN102896789A (en) | 2013-01-30 |
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