Title of invention: Extrusion Molding Equipment and Process for Producing Cylindrical Film

Technical Field

[0001] The present invention relates to an extrusion molding equipment; and a process for producing a

cylindrical film. More specifically, the present

invention relates to an extrusion molding equipment capable of steadily producing a film having excellent quality, a process for producing cylindrical film using the extrusion molding equipment, and a process for producing- pneumatic tire using the cylindrical film. Background Art

10002] it is k own to extrude a melt of a

thermoplastic resin composition or a thermoplas ic elastomer composition comprising as a continuous phase (sea phase) a thermoplastic resin and as a disperse phase (island phase an elastomer dispersed in the

thermoplastic resin by an extrusion molding equip en into a molded article in the form of film, etc. (see i?LT 1) , Such a material easily flows when stirred by a screw, but exhibits rapid decrease i fluidity in a pipe or die where no screw is ' rovided, and consequently, the retention time of the thermoplastic resin composition or thermopiastic elastomer composition in the pipe or die is increased. Further, due to the decrease in fluidity of the thermoplastic resin composition or th moplastic elastomer composition in the pipe or die, the pressure inside the pipe or die increases, and as a result the discharge rate per scre speed of an extruder connected to the pipe or die is decreased, and shear heating and stagnation cause the thermo lastic resin composition or thermoplastic elastomer composition to deteriorate. The de eriora ion of th thermoplastic resin composition or thermoplastic elastomer composition due to the stagnation and shear heating in the pipe or die cause a poor appearanc in the resulting film, or cause a problem that the extrusion pressure and extrusion torque generated by the extrusion molding equipment exceed the allowable upper limit values for the extrusion molding equipment, and thereby causing; difficulty in extrusion molding, fur er, when a thermoplas ic elastomer coiRposition is extrusion-molded as a cylindrical film having a

predetermined size in accordance with the -application- thereof using an extrusion molding equipment comprising a cylindrical spiral die, if the ratio of the inner diameter of the outer lip of the cylindrical spiral die used for the production to the ma imum diameter of the extruded cylindrical film,, that is, she blow ratio, is high,:, there was .a problem that the extent of shrinkage of the cylindrical film obtained after extrusion molding is large, and the resulting cylindrical film therefore has problem in that it has a low dimensional precision and ;a low dimensional stability and wrinkles are generated in the resulting cylindrical film.

Citations hist

Patent Literature

[0003] P ^' LT 1; Japanese unexamined Patent Publication (JP-A) Ho. 2015-143317

Summary of Invention

Technical Problem

[0064] In view of the above conventional problems, the present invention is directed to provide an extrusion molding equipment capable or restraining the cylindrical film after extrusion molding from shrinking, and as a result capable of producing a cylindrical film having excellent dimensional stability with a high dimensional precision.

[0005J The inventors have carried out experiments to achieve the above object, and as a result found that, in an extrusion molding equipment for producing a

cylindrical filsn, when the extrusion molding equipment comprises an extruder for mere extruding a stock material and a single-layer or multilayer cylindrical spiral die attached to a discharge port of the extruder, the cylindrical spiral die comp ises an outer foody, a mandrel j an outer- lip, an inner lip, and an annular discharge port formed between the outer lip and inner lip, and,- when a target value of a diameter of the cylindrical film to fee produced by the extrusion molding equipment is represented by l _f an inne diameter of the outer lip of the cylindrical spiral die is represented by )2, an outer diameter of the mandrel o th cylindrical spiral die is represented by B3, and an inner diameter of a cylinder of the extruder is represented by D , Dl, D2 , B3 _< and D satisfy specific relationship, it is possible to restrain th cylindrical film after extrusion molding from shrinking, and as a result it is possible to produce a cylindrical film having excellent dimensional stability with a high dimensional precision, and

consequentl comple ed the present invention.

Solution to Problem

[0GOS] The present invention includes the following

[Embodiment 1] to [Embodiment 7] .

[Embodiment I] An extrusion molding equipment

comprising : (A) an extruder for melt extruding a stock material, having a cylinder and a discharge port; and

{Bj a single- layer or multilayer cylindrical spiral die attached to the discharge port of the extruder (A) _; w erein the cylindrical spiral die ( » comprises an outer foody, a mandrel, an outer lip, an inner lip, and an annular discharge: port formed between the outer lip and inner lip, ana when a target value of diameter of the cylindrical film to be produced by the extrusion molding equipment is represented by Dl, an inner diameter of the outer lip is represented by D2 , an outer diameter of hhe ^: mandrel is represented by D3 , and an inner diameter of the cylinder of the extruder (A) is represented by D4, Dl, D2, 03, and D4 satisfy a relationship of the

following formulas (1) o (4) :

Dl==m:p2 (1)

wherein ^¾v ra" is a value in the range of fro 1 to 2.9, m- _^ Q to 76.2 n¾ (2)

D3>2S.4 ni {3}

D3--D4-0 to 50.8 mm (4) .

[00071 [Embodiment 2j The extrusion molding equipmen according to Embodiment 1, wherein the stock* material is a thermoplastic elastomer composition comprising a

therrao lastic resin as a continuous phase and an

elastotser as a disperse phase.

[00083 [Embodiment 3] The extrusion molding equipment according to Embodiment 1, wherein D2, D3 ,. and D4 satisfy the relationship of the following formulas (5) and (6) :

D2-D3-0 to 50.8 mm i5)

D4-D3-0 to 25. « (6),

[0009] [Embodiment 4] The extrusion molding equipment according to any one of Embodiments 1 to 3 wherein a ratio of ah effective length L of a -screw to a screw diameter D of the extruder, L/D, is 32 or more.

100101 [Embodiment 5] A process for producing a cylindrical film, comprising:

providing the extrusion molding equipment according to any one of Embodiment 1 to 4;

extruding a molten thermoplastic elastomer

composition from extruder (A) to cylindrical spiral, die (B) , the mol en thermoplastic elastomer composition

comprising a thermoplastic resin selected from the group consisting of a polyamide-bas.ed resin, a polyvinyl -based resin, a polyester -based resin, and a blend of two o more o these resins as a continuous phase, and a modified elastomer as a disperse phase; and

extruding th molten ther oplastic elastomer composition from cylindrical spiral die (B) to form a cylindrical f 1m .

C 0111 [Embodiment 61 A process for producing a pneumatic tire comprising :

producing a cylindrical film by the process

according to Embodiment 5 ;

cutting the resulting cylindrical film in accordance with a size of the pneumatic tire to be produced to form an inner liner having a splice- less cylindrical shape

forming a green tire comprising the inner liner; and vulcanizing the green tire to form a pneumatic tire.

[0012] [Embodiment ?j A process for producing a . pneumatic tire comprising:

producing a film for a pneumatic tire inner liner by the process according to Embodiment 5;

cutting the resulting cylindrical film in accordance with a size of the pneumaie tire to be produced to form an inner liner in the form of sheet;

forming a green tire comprising the inner liner; and vulcanizing the green tire to form, a pneumatic tire.

[0013] Advantageous Effects of Invention

According to the extrusion molding equipment of the present, invention, it is possible to stead ly produce a cylindrical filra having excellent dimensional stability with a high dimensional precision. Further, according to trie extrusion molding equipment of the present invention, it is possible to set the inner diameter of the outer lip of tlie cylindrical spiral die corresponding to the targeted diameter of the cylindrical film to : produced by the extrusion molding equipment and to set the outer diameter of the mandrel in accordance with the set inner diameter of the oute lip, and therefore it is possible to efficiently set the optimal equipment configuration of the- extrusio molding equipment in accordance with the desired size f the filra.

Brief Description, of Drawings

[0014] [FIG. Ij FIG. 1 is a schematic view showing one embodiment o:f a process for producing a .cylindrical film using an extrusion molding equipment according to the present invention.

[PIS. 2.3 FIG. 2 is a schematic view showing another embodiment of a process for producing a cylindrical film using an extrusion molding equipment according to th present invention.

[FIG. 3j FIG. 3 is a schematic vertical cross- sectional view of one embodiment of a cylindrical spiral die in an extrusion molding equipment according to the present invention .

[FIG. 4] FIG , 4 is a schematic vertical cross- sectional view of another embodiment of a cylindrical spiral die in an extrusion molding equipment according to th present invention . Description of Embodiments

Γ0015] Embodiments of the present invention will be explained below in detail along referring to the attached drawings. FIG. l shows one embodiment or an extrusion molding equipment used in the present invention. This extrusion molding equipment 1 comprises extruder 10 comprising stock material feeder 11. cylinder 12 and discharge port 13, and cylindrical spiral die 20

connected to discharge port 13 of extruder 10. A raelt- extrudable stock material is introduced into cylinder 12 set to a melt -extruding temperature from stock mate al feeder 11 of extruder 10, and the stock, material is allowed to melt in cylinder 12 while extruding it by a rotating screw (not shown} to the discharge port aide, and then the resulting molten, stock material is extruded from discharge port 13 to cylindrical spiral die 20.

00163 Cylindrical spiral die 20 has an outer body, an outer lip., a mandrel, and an inner, lip, as ex lained below along referring to FIGS . 3 and 4. Molten stock material is extruded upwardly as a cylindrical film from annula discharge port 21 which is defined as a gap "G" between the inner lip and. the outer lip. The annular discharge port has an outer diameter of D2. Cylindrical spiral die 20 further has an air passage (not shown} for- blowing air inside the cylindrical film, as necessary. It is possible to expand cylindrical film Fl by the pressure of the air blown therein. Extruded cylindrical film Fl is screeched in the circum erential direction by the air enclosed inside cylindrical film Fl and is also stretched in the vertical direction (machine direction or

conveyance direction) by drawing the cylindrical film in the vertical direction. Cylindrical film Fl can be cooled by blowing a. cooling gas to the outside of extruded cylindrical film FX with air ring device 30 provided above annular discharge port 21 and in proximity to the outer circumferential side of annular discharge port 21, in concentrically to annular discharge port 21, .Examples of the cooling gas include air, inert gases (for example, nitrogen and argon) ,. sec . Air ring device 30 has at least one cooling gas outlet port 31 which blows out the cooling gas. Although the structure of the air ring device is not particularly limited, the air ring device, bu is preferably a dual lip type which enables recise cylindrical formation.

Q0171 When cylindrical film Fl extruded from annular discharge: port .21 of spiral die 2:0 is allowed to expand into a bubble, cylindrical film Fl gradually expands as it is conveyed upward and expands until th diameter of cylindrical film Fl reaches the ma imum, diameter. The term: "the diameter of the cylindrical film* ^' refers herein to the - fs&xiifluro value of the outer diameter of the cylindrical flits. Th target value of Dl of the diameter of th cylindrical, film is. determine i accordance with the application of the film. The value of Dl is not particularly limited _. , but in the ease that the film produced by the extrusion molding equipment of the.

present invention is used, for example, as an inner liner for the pneumatic tire of a passenger car, Dl is

typically from GO mm to 800 mm. In the present

invention, the blow ratio is defined as D1/D2. In FIG. 1, a pair of stabilising plates 40A, 40B facing each other are provided above air ring device 30. Cylindrical film Fl is cooled along with being conveyed upward and. is deformed into flat while being conveyed by the pair of stabilizing plates 40A, 4GB facing each other. In place of the pair of stabilizing plates 40Ά, 40B, for example, a plurality of guide rollers arranged in parallel with each, other in a direction perpendicular to the conveyance direction of bubble B may be used, Above stabilizing plates 4OA, 4 OB, a pair of pinch rolls 50A, SOB are arranged for folding cylindrical film Wl deformed into flat by stabilizing plates 4 OA, 4DB, into a sheet.

Cylindrical film ¾ lay- flat ilm) F2 which is obtained by folding the cylindrical film by the pair of pinch rolls 5OA, 508 is wound up by windup roil 60 through guide rolls 51, 52Ά, 52B ^: _; 53. Before cylindrical film ?2 is wound ^' u by the windup roll or after i is wound up, cylindrical .film F2 may be sli longitudinally along one or both sides to form one or two films _; as necessary, £00X83 FIG. 2; shows another embodiment of an extrusion folding equipment according to the present invention. This extrusion molding equipment comprises a first extruder iOA for extruding the molten first stock material, and a second extruder XOB for extruding the molten second stock material. The first extruder IOA and the second extruder 10B respectively comprise stock material feeder 11A, 11B, cylinder 12A, 12B, and

discharge port 13 ^: . A multilayer cylindrical spiral die is attached to each of discharge port 1.3A of the first extruder IOA and discharge port 13 B of the second extruder iOB. The stock material melt extruded from the first extruder and the stock material melt extruded from the second extruder may have the sass composition or may have different compositions. A multilayer film can be produced using an extrusion molding equipment having a configura ion as shown in FIG. 2.

[0019] PIG. 3 is a schematic vertical cross-sectional view of one embodiment of a cylindrical spiral die used, in an extrusion molding equipment according to the present invention. In the embodiment shown in FIG, 3, cylindrical spiral die 300 has annular discharge port 3.10, inlet pore 320 for a molten stock material supplied from an extruder, outer body 330 having a hollow chamber extending i the center axis C direction, annular outer lip 340 arranged above outer body 330 coaxially to and adjacent with outer body 330, mandrel 350 arranged inside the hollow chamber coaxially with outer body 330, and inner lip 360 arranged coaxially with and adjacent to m ndrel 350. The annular discharge port 310 is defined as a gap G between outer lip 340 and inner lip 3601 Outer lip 340 is connected to outer body 330 by, for example, bolts or other fasteners (not shown) , and inner lip. 360 is connected to mandrel 350 by, for example, bolts or other fasteners (not shown) . Inlet port 320 is formed at the bottom surface of mandrel 350, and- mandrel 350 further has flange- art 352, at least one spiral groove 354 formed at the outer circum erential surface, and channel 356 extending trots inlet port 320 to the starting point of spiral groove 354, Outer body 330 is connected to flange part 352 of mandrel 350 by, for example, bolts or other fasteners (not shown) . When the mandrel has two or more spiral grooves, channel 356 branches and extends until the starting points of the spiral grooves or the mandrel is provided with two or more inlet ports and two or more channels extending from these inlet ports to the starting points of the spiral grooves. The molten stock material extruded from the extruder is introduced into spiral groove ¹ 354 from inlet port 320 through channel 356. The molten stock material introduced into spiral groove 354 flows through the space between outer body 330 and mandrel. 350 i the extrusion direction while forming a leakage flow, thereby forming a cylindrical shaped flow in the center axis C direction, and is extruded as a single-layer cylindrical film from annular discharge port 310 through the space between inner circumferential surface 342 of crater lip 340 and outer surface 362 of inner lip 3SO.

[0020] FIG. 4 is a schematic vertical cross-sectional view of another embodiment of a cylindrical spiral die used in an extrusion molding equipmen according to the present invention. FIG. 4 illustrates one embodiment of a cylindrical spiral, die whic can be used, when producing a multilayer film. Cylindrical spiral die 400. illustrated in FIG. 4 has annular discharge port 410, inlet port 42Qa for a first molten s ock material supplied from a first extrud ^' fer , and inlet port 42Qb for a second molten stock material supplied from a second extruder. Cylindrical spiral die 40Ό further has: an cuter body comprised o a first outer body element 432, second outer body element 434, _: and third outer body element 436 stacked in the center axis C direction, A space in w ic the first molten stock material is introduced and through which the first molten stock material flows is formed etween the top surface of the first outer body element 432 and the bottom surface of the second outer body element 434, and a space in which the second molten stock material is introduced and through which the second molten stock material flows is formed between the top surface of the second outer body element 434 and rhe bottom surface of the third outer body element 436. The first outer body element 432, second outer body element 434,. and third outer body element 436 are connected by, for example, bolts or other fasteners (not shown) , and the outer body has a hollow chamber extending in the center axis C direction. Cylindrical spiral die 400 further has annular outer lip 440 arranged coaxially with and adjacent to outer body,, a mandrel 450 arranged inside the hollow chamber eoaxiaiiy with outer body 432, and inner lip 460 arranged eoaxialiy with and adj cent to mandrel 450.

Annular discharge port 410 is defined as the gap G between outer lip 440 and inner lip 460, Outer lip 440 is connected to the outer body by, for example, bolts or other fasteners {not shown) , ana inner lip 26 is

connected to mandrel 450 by, for example, bolts or other fasteners (not shown). Mandrel 4S0 has flange part 452, and the outer body is- connected at the first outer body element 432 to flange part 452 of mandrel 450 by, fey example, bolts or other fasteners (not shown) . Inlet port 420a is formed at the outer circumferential surface of the first outer body element 432, while inlet port 420b is formed at the outer circum re ial surface of the second outer body element 434.- The first outer body element 432 has a least one spiral groove 432a formed on the top surface ana channel 432b extending from inlet port 420a to the starting point of spiral groove 432a. while the second outer body element 434 has at least one spiral .groove 434a formed on the to surface and channel 434b extending from infer port 420b to the starting point of spiral groove 434a. ¾hen the first and second outer body elements respectively have two or more spiral grooves, channels 432b and 434b branch and extend to the starting points of the respective spiral grooves or rhe first and second outer body elements are provided with two or !iiore inlet ports and two or more channels

extending from these inlet ports, to the starting points of the spiral grooves. The first and second molten stock materials extruded from the first and second extruders are introduced into spiral grooves 432a and 434a from inlet ports 420a and 420b through channels 432b and 434b. The first molten stock material, introduced into spiral groove 432a flows through the space between the first and second outer body elemen s in the extrusion direction while forming a leakage flow, and then flows through the space between mandrel ^' 450 and the second outer body element 432 in the extrusion direction, thereby forming a cylindrical shaped flow in the center axis C direction. The second molten stock material introduced into spiral groove ^' 434a flows through the space betwee the second and third outer body elements in the extrusion direction while forcing a leakage flow, and then merges wit the cylindrical flow of the first molten stock material. The cylindrical flows of the first and second molten stock materials move in laminar flow through the space between the third outer body element 436 ^: and mandrel 4S0 In the extrusion direction, pass through the space between the inner surface 422 of the outer lip and the outer surface 462 of the. inner lip,- and is extruded from annular discharge port 410 as a cylindrical film having a two- layer structure. For example, by using the

cylindrical spiral die having an oute body comprised of four or more outer body elements, it is possible to

Obtai a cylindrical film with more layers.

[0021] In th extrusion molding equipment of the present invention, inner diameter D2 of the outer lip is selected so that diameter Dl of the cylindrical film, extruded from the annular discharge port and inner diameter D¾ satisfy the relationship of the following formula {1} ;

Dl«mxD2 (1)

wherein "m" is a value in the range of from 1 to 2,9. By satisfying the condition of the above formula (1) it is possible to produce a film with a high, dimensional precision, i.e., a low shrinkage factor, and therefore it is possible to obtain a film as designed- If D1/D2 exceeds 2.9, the shrinkage factor of the cylindrical film exceeds 1,5% and the dimensional precision is decreased. A low dimensional precision due to high shrinkage factor causes, for ex mple, in increase in delamina ion failure at the t nie of lifting during the green tire molding process due to the shrinkage tension of the film, or cause dif iculty in inserting the cylindrical film in a tire molding drum. .Further, if the cylindrical film has a high shrinkage factor, wrinkles are generated in t e cylindrical- film, and accordingly when the cylindrical film is stacked with other rubber members during, for example-, the production of a pneumatic tire, air

entrapment or folding of the film occurs easily.

[0022] The inner diameter D2 of the outer lip is selected so ^: as to satisfy the relationship of formula (25 below with the outer dianseter D3 ^: of the mandrel.

D2.~D3«0 to 76.2 mm (0 to 3 inch) { 2 } Preferably, D2--D3-0 to 50.8 mm (G to 2 inch} .. By

satisfying the condition o the above formula L2) , it is possible to avoid deterioration of the material due to stagnation or an excessive increase in. extrusion

pressure. When D2-D3 exceeds 76.2 mm, the material is deteriorated due to stagnation, thereby making it difficult to carry out extrusion molding of the material into a cylindrical film, and the resulting cylindrical film has a large number of lumps. In the present

invention, the term *outer diameter D3" of the mandrel refers herein to the outer diameter of the base of the mandrel .

[00233 Outer diameter D3 of the mandrel is selected so as to satisfy the relationship of the following formula {3} :

D3>25.4 mm (1 inch) (3} By satisfying the condition of the above formula (3) , a cyl ndrical film having an excellent quali y can be obtained. If D3 is less than 25.4 m, it is -difficult to ^■ obtain a cylindrical film having a low shrinkage factor. £0024] Regarding the relationships of formulas (1) , {2} , and {3.) , the ratio of Dl to Ώ2 and the difference between D2 and D3 are important in the point of

preventing deterioration of the molten stock: material and thereby obtaining a film having excellent quality. When a thermoplastic elastomer Composi ion is used s a. stock material for the film, it is believed that, in a series of the processes in which the thermoplastic elastomer composition is melt extruded from the discharge port of the extruder in the cylindrical spiral die, passes through the space between the outer body and the mandrel of oute diameter D3 passes through the space between the inner surface -of the outer lip and the outer surface of the inner lip, and is extruded from the annular discharge ^' port of inner diameter D2 as a cylindrical film, arid the cylindrical film reaches the desired diameter Dl, it is possible to suppress excessive orientation of th elastomer particles present as a disperse phase in the thermoplastic elastomer composition in the stretching direction and to restrain shrinkage of the cylindrical film due to the shrinkage stress of the elastomer particles. Furthermore, regarding the

relationship of the above formula {2} , the larger the difference between D2 and D3 ,. the longer the channel of the molten stock material, the higher the pressure inside the cylindrical spiral die, the more uneven the flow of ^' the molten stock material, the greater the stagnation, and the more deteriorated the molten stock material.

[0025] As the extruder used in the extrusion molding equipment of the present invention, a single -screw or twin-screw extruder can be used. The extruder is not particularly limited so long as it can melt extrude the stock material to the cylindrical spiral die. The extruder comprises: a cylinder having an inner diameter 4 , B4 and D3 satisfy the relationship of the llowing formula (4) ;

B3-D4= 0 to: 50.8 mm iO to 2 inches) (4) .

Preferably, D3~Di«© to 25. mm (I inch) . When a

thermoplastic elastomer composition is used as a stock material of the film, using an extruder having cylinder inner diameter reiatively larger than the outer diameter of the mandrel enables a hig extrusion .r e: to be reached at a low screw speed and it is possible to

restrain the elastomer particles present as a dispersed phase in the thermoplastic elastomer composition from deteriorating due to the shear heating and stagnation, if D3-D4 exceeds 5Ό„ 8 ram, in order to achieve a high discharg rate, i is necessary to increase the screw speed of the extruder. The shear heating and stagnation can readily cause deterioration of the thermoplastic elastomer composition.

[0026] The extruder has a ratio of the effective length L of the screw to the screw diameter D, h/Ό, of preferably 28 or more, more preferably 32 or more. The term ^effective- length of the screw" refers herein to the length defined by JIS B 3650. If L/D is less than 28, it is difficult to uniforml melt the stock materials while suppressing the heating of the stock materials introduced in the cylinder of the extruder. [0027 The lip gap G of the cylindrical spiral die is preferably from 0.5 to 3.0 mm. The discharge rate Q of che molten stack material extruded from the annu l discharge port of the cylindrical spiral die is

preferably from 20 to 150 kg/ht

[0028] The extrusion molding equipment of the present invention ca produce a film having high gas barrier properties from a. thermoplastic elastomer composition.. Although the thickness of the ilm produced using the extrusion molding equipment of the present invention is not particularly littdted, when the ^' film produced using the extrusion molding equipment of the present inventio is used, for example, as an inner liner for a pneumacie tire, the film can achieve a sufficient air pressure retention rate at a thickness of from 0.01 to 0.2 mm.

[SG29j The cylindrical film produced by the extrusio molding equipment of the present invention can be used as a splice-less cylindrical film or a film in the form of sheet after being cut to a predetermined size in

accordance with the application thereof. Compared with a cylindrical film having a splice, a splice-less

cylindrical film has an dva tage of capable of avoiding the failure due to concentration of stress at the splice. Therefore, the cylindrical film produced by the extrusion, molding equipment of the present invention is useful in various applications where the absence of splice is desired, for example, as a member used, in th production of a pneumatic tire, particularly, as an inner liner.

Conventionally, when a splice-less cylindrical inner- liner is used in the production of a pneumatic tire, if the shrinkage in the circumferential direction of the cylindrical film corresponding to the tire

circumferential direction is large, delamina ion failure may occur at the time of forcing a tire due to the shrinkage of the cylindrical film. The cylindrical film produced by the extrusion molding equipment of the present invention has reduced shrinkage after extrusion molding, and therefore is capable of minimizing the delatnination failure. Further, there are problems that, if the circumf rential length of the cylindrical film is shorter than the predetermined value, then it is

difficult to dispose the outer peripheral surface of the tire molding drum, or conversely, if the circumf rential length of the cylindrical film is longer than the predetermined value, then the tension of the cylindrical film, on the outer peripheral surface o the tire molding drum is weak and Wrinkles are readily formed when laminating the cylindrical film with other members. I particular, when a large-size inner liner is produced at a high blow ratio in order to produce a large-size pneumatic tire, these problems are remarkable, and the yield in the productie of pneumatic tires is low. The film produced by the extrusion molding equipment o the presen invention has improved ^' dimensional precision and dimensional stability, and therefore can improve the yield in the production of pneumatic tires.

(00301 A. thermoplastic resin composition or a

thermoplastic elastomer composition comprising as a continuous phase (sea phase) a thermoplastic resin and as a disperse phase (island phase) an elastomer dispersed in the thermoplastic resin can be used as the stock -material for producing a cylindrical film by the extrusion molding equipment of the present invention. Examples of the thermoplastic resin which can constitute the

thermoplastic resin composition or thermoplastic

elastomer composition include po-lyaraide-based resins, polyvinyl-based resins, polyester-based resins,

polynitrile -based resins, polyraethacrylate -based resins, ceilu.lo.sic resins , fluororesins, imid -based, resins, polystyrenic resins, poiyolefinic resins, etc. The thermoplastic resin composition or thermoplastic

elastomer composition may include at least one

thermoplastic resin. The film produced from the

thermoplastic elastomer composition is lighter in weight compared with an inner liner based on conventiona.1 butyl rubber and, further, has an air pressure retention rate which is equal to or higher than that of an inner liner based on conventional butyl rubber, and therefore it is preferable to produce pneumatic tire inner iiner from a thermoplastic elastomer composition. The W en a

thermoplastic elastomer composition is used as the stock material, the thermoplastic elastomer compositio

preferably comprises -combination of a thermopl stic resin having high .barrier properties and a modified elastomer having high affinity to the thermoplastic resin.

t00311 Examples, of polyamide-based resins include, Nylon 6 {86} , Nylon 66 ( 66) , Nylon 46 (N46) , Nylon II

(Nil), Nylon. 12 (NI2), Nylon 69 (N69) , Nylon 610 (NS10) , Nylon 612 {NS12} , Nylon 6/66 copolymer (Νδ/66} , Nylon 6/610 copolymer (E6/61Q) , Nylon 6/66/610 copolymer

( 6/6S/610) ; serai-aromatic and all-aromatic nylons such as Nylon !KDS (MXDS) , Nylon ST, Nylon 3T, Nylon 6/6T copolymer; Nylon 66/PF copolymer. Nylon 66/PPS copolymer, a copolymer of a polyaTid.de and polyethsr (for example, a copolymer of at least one type of the above Nylon and a polyether) , and -alkoxyaikylates thereof, for example methoxyjseth late of Nylon 6, methoxymethylate of Nylon 6/6101 ethoxy ethy ^' late of Nylon 61.2, etc. Examples of polyvinyl -based resins include ethylen -vinyl acetate copoly er (EVA) , pol {vinyl alcohol} (PVA) , vinyl alcohol-ethylene copolymer CBVOH) ^' , poly (vinylidene chloride! (SVDC) , poly (vinyl chloride) (PVC) , vinyl ehioride/vinyiidene chloride copolymer, vinylid e chloride/raethylacryl&te copolymer, vinyl idene

chloride/acryionitrile copolymer , etc. Exa les of polyester-based resins include poiybutyiene terephthaiate ( P.B ) , polyethylene terephthaiate (PET) , polyethylene i soph haiate (PSD _f PET/PKI copolymer, poly rylate (PAR) _; poiybutyiene naphthalate (PER) , liquid crystal

polyesters , poiyo^xyalkyienediisyidic acid/polybutylat terephthaiate copolymers, ar other a-rbmatic polyesters, a copolymer o a polyester and poiyecher, a copolymer of a polyester and an aliphatic polycarbonate, etc. Examples of polynitrile-hased resins include polyaerylonitriie (PAN) , poiymethacryicnitrxie, acrylonitriig/styrene copolymer (AS } , ffiethacrylonitrile/st rene. ^{■ ■} copolymer, meth cryionitrile/styrene/butadiene copolymer, etc .

Examples of pal:ysethaCrylate--based resins include poly (methyl me hacrylate ) ( _: ΡΜΜΆί , poly (ethyl

snethacrylate) , etc. Ex m les of cellnlo ic resins include cellulose acetate, cellulose acetate bu.tyra.te, etc.

Examples of fiuororesins include, pol (vinylidene

fluoride) (PVDF) , poly (vinyl fluoride) CPVF) ,

polychiorof!uoroethylene (PCTFE) , tetrafl or©ethylene/ ethylene copolymer iSTFE) , etc. Examples of imid©-based resins include aromatic polyimides (PI), etc. E l s of polysiyrenic resins include polystyrene ⁽ PS), etc,

Examples cf polyolefinic resins include polyethylene (PK? , polypropylene (PPS , etc Among these thermoplastic resins. Nylon 6, Nylon 66, Nylon 46, Nylon 11, Hylon 12, Nylon 69, Hylon 610, Nylon 612 , Nylon 6/66, Nylon 6/66/12, and Nylon 6/66/610 and semi -aroma ic and all- aromatic nylons such as Nylon MXD6 , Nylon 6 , Nylon ST, d Hylon 6/6T are preferred, in view of gas barrier prope ties .

[0032] Common ingredients for common thermoplastic resin compositions , such as fillers, reinforcing agents, processing aids, stabilisers, antioxidants, etc., may optionally be added au. a common amount to the

thermoplastic resin which constitutes the thermoplastic resin composition or thermoplastic elastomer composition which is extruded usi g the extrusion molding equipment according to the present invention. In view of th gas- barrier properties and heat resistance of the film obtained by extrusion molding of the thermoplastic resin composition or thermoplastic elastomer composition, it is preferred to not add a plasticizer to the ^: thermoplastic resin composition or thermoplast ic elastomer composition, A film having a reduced shrinkage after extrusion molding can be produced even if a plaatieise such as, for example, higher alcohol-based piasticisers, aromatic suifonea ide-based plasticisers, phenolic piasticizers , etc., conventionally used in the extrusion molding of a thermoplastic resin composition or thermoplastic

elastomer composition, is not incorporated into the thermoplastic resin composition or thermoplastic

elastomer composition, and therefore it is possible to prevent the decrease in the gas barrier properties and heat resistance which may be caused when a pla.stici.2er is added to a thermoplastic resin composition or

thermoplastic elastomer composition.

[0033] The thermoplastic elastomer composition comprises ac least one rubber dispersed in at least on thermoplastic resin, wherein the at least one thermoplastic resin constitutes a matrix phase (or a continuous phase) and the rubber constitutes a disperse phase (or a; d scontinuous phase) .. The rubber is dispersed in the form of particles in the thermopl stic resin.

Exam les of the rubber which can constitute the

thermoplastic elastomer composition include diene -based rubbers and hydrogenated products thereof, olefi -based rubbers, halogen-containing rubbers, silicone rubbers, sulfur-cont ining rubbers , fluoro rubbers, etc. Exam les of diene -based rubbers and hydrogensted products thereof include natural rubbers (HE.) , isoprene rubbers (IR) , epoxidised natural rubbers ,. s:tyrene -butadiene rubbers (SS ) , butadiene rubbers (BR) (high-cis BR and low- cis BE) , aorylonitrile butadiene rubbers (NBR) , hydrogenated N3 _f hydrogenated SBR., etc. SxaESples of olefin-based rubbers include ethylene propylene rubbers (SPM) , ethylene propylen diene rubbers (BPD ) , tna:leic acid- modified ethylene propylene rubbers iM- ^' EPM) , tsaieic anhyd ide -modified thylene-a-o:Iβfin copolymers,

ethylene -.giveidyl methacryiate .copolymers, rnaleic ■anhydride^modified ethylerie-ethyl aeryl te copolymers (modified EEA) , butyl rubbers illE) ,, copolymers of isobutylene and an aromatic vinyl or diene mo om r (for example, acid anhydride-moditied styrene - isobutylene- styrene block copolymers) , acrylic rubbers (&C ) , ionosers , etc. Examples of halogen-containing rubbers include halogenated butyl rubbers such as brominated butyl rubbers (Br-IIR) , chlorinated butyl rubber (CI- IIR) .« etc. , brominated isobutylene- -methyl styrene copolymer (Br-IPMS) , halogenated isobutylene-isoprene copolymer rubbers, chloroprene rubbers {CR} , hydrin rubbers (CHE; , chiorosulfonated polyethylenes. (CSM) , chlorinated polyethylenes (CM) , maleie acid-modified Chlorinated polyethylene© (M~ CM| , etc. Examples of silicone rubbers include methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber, etc. Examples of sulfur- containing rubbers include polysul ide rubbers, etc. Exatspl.es of fluoro rubbers include vinyl idene fluoride rubbers , fluorine- containing vinyl ether rubbers , tetrafluoroethyiane- propylene rubbers, fluorine- containing silicone rubbers, fluorine-containing phosphazene. rubbers, etc. Among these rubbers , brominated isobutylene-p-raethylstyrene

copolymers, maleic anhydride-modif led ethylene- - olefin copolymers, and blends thereof ar preferred in view of gas barrier properties, durabilit and processahility . [Q03 ] Examples of the combination of the

thermoplastic resin and rubber, capable of forming the thermoplastic elastome composition which can be use in the present invention include a combination of ss

poiya ide-based resin, an ethylene-vinyl alcohol

copolymer or a blend, of polyamide-based resin and ethylene -vinyl alcohol copolymer with brosrlnated

isobutylene-p- methyl sfcyren copolymer rubber, a maleic anhydride-modi ied ethylene- -olefin copolymer, or a blend of brominated isobutylene-p-methyl sty ene copolymer rubber and a maleic anhydride-modified ethylene~cr~olefin copolymer, and a combination of butyl rubber having excellent gas barrier properties and a polyamide-based resin is preferred. Among these, a combination of a brominated isobutylene-p-methyistyrene copolymer rubber, which is a modified butyl rubber, and one or more polyamide-based resins (for example Nylon 6, Mylon S S6, Hyion 612, etc.) is specifically preferred in view of achieving both fatigue resistance and gas barrier properties, when a thermoplastic elastomer composition is used as a stock material of the film, due to the effect of the elastomer component dispersed in the thermoplastic resin, the viscosity of the thermoplastic elastomer composition tends to be high, resulting in the .decrease in the forrnabili , Therefore, when an inner liner film with high durability and high harrier properties is to be produced, it is preferable to reduce the difference between D2 and D.3 under the conditions of the above formula (2} .

[0035] Th rubber particles included in the

thermoplas ic elastomer composition, may contain carbon black! silica, o other reinforcing agents (fillers) , cross-linking agent., antioxidant, processing aid. or other compounding agents that are corns-only blended into a rubber composition to. the extent that the effects of the- present invention ere not impaired.

[0036] Before the thermoplastic elastomer composition is introduced into extruder io, the thermoplastic elastome compositio can he prepared in advance by melt- kneading at least one thermoplastic resin, at least one rubber, and optionally additives by, for example, a single-screw or twin-screw kneading extruder, to disperse the rubber particles as a disperse phase in the

thermoplastic resin which forms a matrix phase. The weight ratio of the thermoplastic resin to the rubber is preferably from. 10/90 to SO/10, and more preferably from 15/85 to 90/10, but is not limited thereto. In order to fix the dispersed stat o the rubber in the

thermoplastic resin, the rubber is preferably dynamically cross- linked while melt-kneading the thermo lastic resin and rubber. The term "dynamic cross- linking" refers herein to cross-linking simultaneous with melt-kneading . The melt -kneading temperature may be equal to or higher than the melting point of the thermoplastic resin, and is preferably a temperature which is higher than the melting point of the thermoplas ic resin by 20*C, for example, is from 200 to 2S0°Ct Ths total time of the kneading operation is not particularly limited, but is usually from 1 minute to 10 minuu.es. The thermoplastic elastomer compositio which is obtained afte melt -kneading the thermoplastic resin and the rubber can be extruded into, for example, a strand form, and then peiletized with a resin peliatizerl

[0037] The -cross-linking agent can be suitably selected depending on the type of the rubber and is not particularl limited. Examples of the cross -linking agent include zinc oxide., stearic acid, sine seearate,

magnesium oxide, m-phsrsyiene bismaieinride, aik lphenol resin, and halogenates thereof, secondary amines (for example, N- (1, 3-dimethylbutyi} -N' -phenyl~p~

phenylenediamine { 6PPD} . a polymerized 2,2,4 -trim¾-t¾yi- 1,3-dihydroquinoline) ,, etc. ¾mong these cross-linking agents, ziric oxide, stearic: acid, and .K ^' --(l,3- dimethylbutyl} -N' -phenyl-p--phenylenediamine are

preferred. The amount of the cross- linking agent is preferably 0.1 to 12 parts by weight, ana more preferably 1 to .9 parts by weight, with respect to 100 parts by weight of the rubber .

[0Q3S] The thermo lastic elastomer composition which can foe extrusion molded using the extrusion molding equipment according to the present invention can be formed in-situ by introducing the thermoplastic resin, rubber, and optionally additives from stock material feeder 11 of extruder 10 which is a single- screw o twin- screw kneading extruder, to the inside of cylinder 12, and melt -kneading them by means of rotating single or double screws. In this case, the resulting thermoplastic elast ^' Qiaer composition can. be extruded as a cylindrical film without being pelletized, from the cylindrical spiral die attached to the discharge port of the

extruder .

[0039] The film produced using the extrusion molding equipment according to the present invention is useful as, for example, a member for a pneumatic tire due to excellent gas barrier properties thereof. The film produced using the extrusion olding equipment according to the- present invention is particularly useful as a gas barrier film, for example, an inner line _r for producing a pneumatic tire.

[00401 Any convent ional process may be used as the process for producing a pneumatic tire.. For example,, w en the film produced using the extrusion molding equipment according, to the present, invention is .used as .an inner liner i the prod ction- of a pneumatic tire, a pneumatic tire can be produced by laminating the film produced by the extrusion molding equipment of the present invention onto a tire molding drum, in cylindrical form;

sequential iy laminating thereon tir members such as a carcass layer, a belt layer, a tread layer, etc., to form a green tire? removing the resulting green tire from the tire molding drum, and subsequently vulcanizing the green tire according to a conventional method. The inner liner laminated on the tire molding drum may be a splice-less cylindrical film obtained by cutting the fil produced using the extrusion molding equipment of the present invention in accordance with the sise of the pneumatic tire to b produced, Alterna iv ly, the inner liner laminated on the tire molding drum may be a film in the form of sheet obtained by catting the film produced using the extrusion molding equipment of the present invention in accordance with the size of the pneumatic tire to be produced. The film produced -using the extrusion molding equipment according to the present invention has a reduced shrinkage with time as described above, and accordingly has fewer wrinkles and is excellent in dimensional stability. Therefore, the film produced using the extrusion molding equipment according to the present invention can suppress defects due to the wrinkles and delamination of the film, thereby reducing the failure rate of the tire after vuicsnination .

Examples

[00413 The present invention will be further explained with reference .a the following examples, and it should he understood that th scope of the present invention is not. limited by these exampl s.

[0042] [Preparation, of herraoplas ie Elastomer

Compositions I to 3]

Among the stock materials shown in.. Table 1 (unit: pfcr , i.e.,. parts by weight with respect, to 100. parts by- weight of total elastomers) below, elastomer 1 was processed into pellets in advance by a rubber peiietizer

(manufactured by oriyam Works) . The elastomer, the: thermoplastic resin, and addi ives (that is.,, plastieizer , antiaging agent, arid cross-linking agent) were charged into a twin-scre extruder (made by Japan Steel Works) at the compounding ratio shown in Table l and were kneaded at 250*0 for 3 minutes. The resulting kneaded mass was continuously extruded into a strand form from the

extruder, cooled with water, and subsequently cut by a cutter to obtain thermoplastic elastomer compositions 1 to 3 in the form of pellets.

[0043] [Physical Properties of Thermoplastic Elastomer Compositions l to 3]

Rubber compositions of the thermoplastic elastomer compositions 1 to 3 were formed into films under the extrusion molding conditions described later. The thermoplastic elastomer compositions 1 to 3 were measured for capillary viscosity by the following test method. The thermoplastic elastomer compositions 1 to 3 were

evaluated for the air permeability coefficient and tire air pressure retention rate by the following test me hods .

1004.4] {1} Capillary Viscosity

A capillary viscosity was measured using Capilograph manufactured by Toyo Seiki Co., Ltd. The shear rate was 1215 cm ^"1 , the measurement teatperature was 250 ^C' C, and the retention time was 10 minutes.

[0045] (2) Air Permeation Coefficien

An air permeation coefficient was determined using a gas permeability measuremen equipment manufactured by GTR Tec Corporation at a measurement temperature of 55°C, in accordance With J2S 7126.

[0046] (3) Tire Air Pressure Retention Rate

.¾ cylindrical film was obtained under ^' the extrusion conditions of Exam le L described later. The resulting cylindrical film had a thickness of l oo πη This

cylindrical film was placed as an inner liner film on a tire molding drum., and a carcass layer, a belt layer, a tread layer, and other members, comprising an

unvuleani:sed rubber, used for normal tire production were sequentially laminated thereon, and the resulting green tire was removed from the tire molding drum. Then, the green tire wa vulcanized by heating according to conventional techniqu to produce a tire having a si e of 19B/6SR15. The produced tire was mounted on a rim, was set to an initial internal pressure of 250· kPa. (air) , and was allowed to stand in. a room at a temperature of 21°C for 3 months . The internal pressure of the tire after standing for 3 raontfes was measured to de ermine the air p essur reten ion rate.

[0047] The results of evaluation are shown in Table 2 below. Table 2 shows that the film produced from the thermoplas ic elastomer composition can achieve a good air pressure retention rate..

[00481 Table 1

Stock Thermopla tic Thermo 1 stio Thermoplastic materials of elastomer las ome elastomer thermoplastic composition i composition 2 composition 3 elastomer- iphr) iphr; i hr;

composition

Elastomer 1 .1. 70 -

Elastomer 2 - 20 80

Elastomer 3 9 ... -

Elastomer 4 10 ...

Ei&stomer s - ~ 20

Thermoplastic - 40 9 resin. 1

Ther op1a.s ic 1S - resin 2

Thermoplastic - resin 3

The moplastic 41

resin 4

Thermo 1astic ·- IS

resin 5

Thermoplas ic - 42resin. 6

Piasticize 25 -

An ioxidant ·· 1. G

Cross -linking - - agent 1

Cross -linking 0. S 3.6 ...

agent 2

Cross- linking 0 , 5 0 7 - agent 3

Cross- linking 0.3 - - agenc 4

Cross -linking - 1.0 1.5 agent S

[0049] Footnote of Table 1:.

Biascomer 1; Srominated i obutylsne-p-methylstyrerte copolymer (Sxxpro® MDX8S-4 from ExxonMobil Chemical

Company) Elastomer 2; Maleic anhydride-modified ethylene~a~ olefin copolymer (Tafmer® MH70.10 from Mitsui Chemicals Inc.) Elastomer 3; Maleic acid-modified ethylene-et yl acrylats copolymer (HPR® ¾J¾20l from Du Pont -Mitsui Polychemicals Co . , Ltd . )

Elastomer 4: Succinic anhydride -modi tied polyisobutylene {DOVER ULSS HIQOO from Dover Chemical Corporation)

Elastomer 5: Epoxy-rnodif ed ethylene -methacryiate copolymer (Bondfast® E from by Sumitomo Chemical Co., Ltd. }

Thermoplastic resin 1; Nylon 6 (OBH Nylon® XOllFS from Ube Industries,: Ltd.)

Thermoplastic resin 2: ylon 6 (UBE Hylon® 1S30FB from llbe industries, Ltd.)

Thermoplastic resin 3: Nylon 6/66 copolymer (UBE Hylon® 5023B from Ufoe Industries, Ltd.)

Thermoplastic resin 4: Kylon 6/66 copolymer (UBE Nylon® 5Q33B fro ^' Ube Industries, Ltd. }

Thermoplastic resin 5: Nylo 6/12 copolymer {UBE Hylon® 7024B from Ube industries, Ltd . )

Thermoplas ic resin 6: Ethylene -vinyl alcohol copolymer (K4S15B f om Mippo Synthetic Chemical Industry)

Plasticiser : Butylbenzene sulfonamide (B -4 from Daihachi Chemical Industry)

Antioxidant : N- ( 1,.3 - di athylbutyl ) -N ¹ -phenyl -p~

phenylenediamine (Santoflex 6PPD from Solutia)

Cross- linking agent 1: Isocyanuiate (THSIC from Shikoku Chemicals; Corporation)

Cross-linking agent 2: Zinc oxide {Sine White .No . 3 from Seido Chemical Industry Co., Ltd.)

Cross- linking agent 3; Beads Stearic Acid from NOP

Corporation Cross-iinkihg agent ; Zinc stearate from Sakai Chemical Industry eo. , Ltd .

Cross-Iinking agent ; Calcium stearate froro NOir

Corporation

[0050] Table 2

[0051] [production of Film]

A cylindrical spiral die (manufactured by Macro Engineering & Technology Inc .5 was attached to a

discharge port of a s?5 wm single-screw .extruder

(manu actured by GM Engineering Co. , Ltd.) to form extrusion molding equipment. The annular discharge port o the cylindrical spiral die was directed upward in the vertical direction ^' (i.e.:. , the direction opposite to the gravity direction) and a pair of guides and a .pair of pinch roils were arranged above the annular discharge port in th vertical direction, ^" A plurality of guide rolls and a wind p roll were arranged so that the cylindrical film extruded from the annular discharge port is folded by a pair of pinch rolls, then the folded cylindrical film is wound up by the windu roll through the plurality of guide rolls. Such an extrusion molding equipment was used to extrude the thermoplastic elastomer compositions 1 to 3 to produce cylindrical films , The cylinder temperature of the extruder was 230°C, and the cylinder temperature of the cylindrical spiral die was 2 0°C. The molten thermoplastic elastomer composition was extruded from the cylindrical spiral die at a discharge rate of 80 kg/hr. The drawing speed of the film was set to 10 m/roin.

[0QS2J <Examples 1 to 14 and Comparative Examples 1 to 10 >

Cylindrical films were obtained by molding

thermoplastic elastomer composition 2 under the extrusion conditions shown in Tables 3: and 4 using the extrusion molding equipment described above. The diameter Dl of each, cylindrical film was determined by measuring the width (W) of a lay-flat film with a ruler and

substituting the measured W value into a formula. pl~2K .n _f wherein π is the circular constant. Examples I to 14 and Comparative Examples 1 to 10 prove the relationship of the above formula (1) for the extrusion molding equipment according to the present invention.

100-531 <Rxampies A to M and Comparative Examples A to

D>

Cylindrical films were obtained by molding

thermoplastic elastomer composition 1 to 3 under the extrusion conditions shown in Table 5 using the extrusion molding equipment described above . The diameter Dl of each cylindrical film was determined in the same manner as described above. Examples A to N and Comparative Examples A to D prove the relationship of the above formulas (1) to (4) for the extrusion molding equipment according to the present invention.

[0054] [Evaluation of Film]

The cylindrical films of Examples 1 to 14 and

Comparative Examples 1 to 10 were evaluated for shrinkage ctor ana appearance . [0055] (A) Shrinkage Factor

The cylindrical films of Examples 1 to 14 and

Comparative Examples 1 to 10 were respectively cut in compliance wit the width of the desired tire inner liner immediately after being formed, and the resulting cylindrical samples were easured for circumferentiai direction length LI. After measurement, the samples were hung in a room and allowed to stand at normal temperature for one week, and then were again measured for

cireumferentiai direction length 1*2 at the same position. The shrinkage factor ^' (%} was determined in accordance with the formula IGOx (L1-L2 ) /LI .

The case where shrinkage factor {%} was 1.5%: or more was rated as "unacceptable" ,

The case where the shrinkage factor s%) was larger than 1.0% and less; than 1.5% was rated as ^acceptable" .

The case where the shrinkage facto (%) was larger than 0.5% and less than 1.0% was rated as "good".

The case where the shrinkage factor (%} was 9..5% or less was rated- as *very good" .

The evaluation results are shown in Tables 3 and 4.

[00563 ί3) Appearance

The cylindrical films of Examples A to N and

Compar ive. Examples A to D were respectively cut in compliance with the width of the desired tire inner liner immediately after being formed, and the samples were evaluated for appearance by visual inspection in

accordance with the following evaluation criteria.

The case where there were no lumps over 1 vm was rated as *1 ^» {very good) .

The case where there were 10 or less lumps of about l was rated as "2" (good) .

The case where there were many lumps of about 1 mm., but not more than. 3 lumps of over about 3 Kim was rated as *3* (acceptable) .

The case where more than 3 l s- of over 3 issm were confirmed in the sample and/or the case where the thermoplastic elastomer composition could not be formed into a film was rated as "4* (unacceptable) -

The case where the extrusion torque o the extruder exceeded the allowable upper limit value was rated as

The evaluation results are shown in Table 5.

Com . Corap . om . Cora . Comp . Ex . 2 35x . 3 Ex, .4 Com . Cam . Com .

EX . 1 Ex. 2 Ex., 3 Ex, 4 Ex. 5 E . 6 Ex. 7 E . 8

Di (m) 2 0 23-3 340 400 450 5.00 220 280 340 400 450 500

D2 (mm) χοΐ, ^' έ 101.6 101.6 101.6 101.6 101 , $ 127 127 127 127 127 1.27

D1/D2 2 , 17 2.7-6 3.3 3.94 4. 3 ^' 4.92 1.73 2.20 .? . S3 3. IS 3.5 3.04

Result of evaluation Good Fair Poor Poor 1 Poor Poor GtoOd Good Fair Poor Poor Poor of shrinkage factor

[00581 Table 4

£00593 Table 5

Extruder D3 Ώ2 Dl Result- of evaluation of- appearance

(rm)

D4 L/D Thermoplaatic Thermb last i c Thermoplastic (mm) elastome elastomer elastomer

composition 1 composition 2 composi i on 3 (lo viscosity) (medlum viscosity ) ί high viscosi y )

Exampl.e A 50 .28 76.2 1.27.0 230 1 1 1

Example B 50 3 76.2 152 ,4 340 1 1 1

Ex m le: C 50 2a 101.6 127.0 280 1 .2 2

Comp* Ex . A 50 8 127,0 127.0 - 4 4 5

Example D 65 28 101.6 127.0 2 0 1, 2 3

i¾an¾>Xe 8 75 32 SO- . s 101 ,-6 2:20 1 .1 1

Example F 75 32 SO, 8 127.0 2ft 0 2 2

Example S 75 28 101.6 101 ,6 220 1 1. 1

Example H 75 28 101. & 152. 220 1 1 2

Example X 75 28 127,0 152,4 280 1 2 2

Example J 75 28 1.2:7.0 203.2 450 3 3. 3

Example 7S 32 .127,0 203 , 2 280 1 2 2

Ccm . Ex . B 75 28 1.2:7.0 228.6 - 4 4 4

Co-Ti ... E .. C 75 28 152 ,4 203.2 [ 4

Example I> .0 32 127. C- 152.4 400 i 1 i 2

Bxample M 90 32 127, 0 .203 ,2 500 1 1 2 1

Corap. Ex. D SO 32 203.2 254.0 - 4 4 5 1

Example N 125 34 152.4 203.2 3 0 1 1 1 i 1

[00601 Tables 3 to 5 above show t h c , if the inner diameter D2 of the outer lip of the cylindrical spiral die, the oute diameter D3 of the mandrel of the

cylindrical spiral die, and the inner diameter D4 of the cylinder of the extruder satisfy the relationship with respect to the target value l of the diameter of the filra for an inner liner, according to the present invention, it is possible to restrain shrinkage of the film after extrusion molding, and as a result it is possible to produce a film for a pneumatic ire inner liner with high dimensional precision. Furthermore, Tables 2 to 5 show that-, even if a high melt viscosity stock aterial which is difficult to process is used, it is possible to produce a pneumatic tire inner liner which is light i weight and has a good air pressure retention rate by using the extrusion molding equipment of the present invention.

Industria1 ¾ Usabilit

[00613 he extrusion molding equipme t ^of present invention can be- suitably used for productio of a ilia,

Further, the film produced using the extrusion molding equipment of the present invention can. be suitably used in various application, for example, as an inner liner of the pneumatic tire for the production: of a pneumatic tire.

Reference Signs List

[00621 1. Extrusion molding equipment

10. Sxt uder

20. 300, 400. Cylindrical spiral die

21. 310, 410, Annular discharge port

30. Air ring device

40A _. , 0B, Stabilizing plates

50Ά, SOB, Pinch rolls 60. Windu roll

Dl. Diameter of cylindrical film

D2. Inner diameter of outer lip

D3. Outer diameter of mandrel

Fl. Cylindrical film

F2. Folded cylindrical film