SPECIFICATION Title of the Invention
SEALING MATERIAL COMPOSITION AND GLAND PACKING CONTAINING THE SEALING MATERIAL COMPOSITION 5 Technical Field [0001]
The present invention relates to a sealing material composition, and also to a gland packing containing the sealing material composition. 10 Background Art [0002]
As a sealing material composition which is used for producing a sealing material, for example, known is a yarn which is disclosed in Patent Literature 1. A yarn of this 15 kind is configured by a tubular member which is formed by knitting or braiding a fibrous material, and a plurality of fibrous members (fibrous expanded graphites) which are filled into the tubular member. [0003] 20 Each of the plurality of fibrous expanded graphites is a flexible long member. The fibrous expanded graphites are charged into the tubular member so that their longitu¬dinal directions approximately coincide with the longitu-dinal direction of the tubular member, and then filled in-2 5 to the tubular member while being flexurally deformed, in

2
a state where the fibrous expanded graphites are randomly arranged (see Fig. 6). [0004] In the tubular member, therefore, uneven gaps are
5 easily formed between adjacent ones of the plurality of fibrous expanded graphites. In a usual sealing material composition, consequently, such gaps are contained in a large number. Moreover, these gaps tend to exist at rela¬tively short intervals in the longitudinal direction of
0 the tubular member. [0005]
In the case where, for example, a sealing material is to be produced by using the yarn, or the yarn is to be conveyed while being wound around a round rod-like member
5 such as a bobbin, when the yarn i s flexed and curved, therefore, there is a case where the yarn is sharply bent in the curved portion, and one(s) of the plurality of fi¬brous expanded graphites is broken. [0006]
0 In such a yarn, when a bending action is applied by an external force, namely, a predetermined amount of flex¬ure is allowed in accordance with the external force, but, when an external force greater than a permissible amount is applied, breakage may possibly occur in the plurality
5 of fibrous expanded graphites. Therefore, there is a pos-

3
sibility that breakage in the plurality of fibrous expand¬ed graphites may cause the performance of a sealing mate¬rial which is produced by using the yarn, to be lowered. [0007] 5 Conventionally, a fluid apparatus such as a pump or a valve is provided with a gland packing as the above-described sealing material. A gland packing of this kind is configured by using an inner core member, and a plural¬ity of yarns which are bundled around the inner core mem-10 ber in a state where the yarns are twisted or braided to¬gether (for example, see Patent Literature 2). [0008]
When the gland packing is to be used, the gland pack¬ing is firstly adjusted so as to have a predetermined lon-15 gitudinal length. While maintaining the state, then, the gland packing is formed into a ring-like shape or com¬press-molded into a ring-like shape according to the shaft member of a predetermined fluid apparatus. Thereafter, the gland packing is stuffed and disposed into a stuffing 20 box which is located in the periphery of the shaft member in the fluid apparatus. [0009]
In the gland packing, the inner core member is con¬figured by the tubular member formed by knitting or braid-25 ing fibrous materials, and the plurality of fibrous ex-

4
panded graphites filled into the tubular member. There¬fore , there sometimes occurs a case where, when the gland packing is curved so as to exhibit a ring-like shape, the inner core member is sharply bent in the curved portion, 5 and one(s) of the plurality of fibrous expanded graphites is broken. [0010]
In the inner core member, when a bending action is applied by an external force, namely, a predetermined
10 amount of flexure is allowed in accordance with the exter¬nal force, but, when an external force greater than a per¬missible amount is applied, breakage may possibly occur in the plurality of fibrous expanded graphites. Therefore, there is a fear that breakage in the plurality of fibrous
15 expanded graphites may cause the sealing property of the inner core member and hence that of the gland packing, to be lowered. Prior Art Literature Patent Literature
20 [0011]
Patent Literature 1: Japanese Patent Application Laid-Open No. 2007-138315
Patent Literature 2: Japanese Patent Application Laid-Open No. 2007-191803
25 Summary of the Invention

5
Problems to be Solved by the Invention [0012]
The invention has been conducted in view of these circumstances. It is an object of the invention to pro-5 vide a sealing material composition which comprises sheet¬like members containing expanded graphite, and which hard¬ly causes the sheet-like members to be broken. It is an¬other object of the invention to provide a gland packing in which the sealing property can be improved. 10 Means for Solving the Problems [0013]
The sealing material composition of the invention is a composition wherein
the composition comprises: 15 a stacked body; and
a long surrounding body which surrounds the stacked body,
the stacked body has
a plurality of sheet-like members each of which is 20 formed into a tape-like shape by expanded graphite,
the plurality of sheet-like members are stacked in a direction which intersects with a longitudinal direction of the surrounding body,
in the plurality of sheet-like members, sheet-like 2 5 members which are adjacent to each other in the stacking

6
direction are disposed to be displaced from each other in the longitudinal direction of the surrounding body, in a relatively movable manner, and
the surrounding body allows 5 the adjacent sheet-like members to be relatively moved in the longitudinal direction of the surrounding body, while maintaining the stacked state of the adjacent sheet-like members.
[0014] 10 In another mode of the sealing material composition of the invention,
each of the sheet-like members has:
one longitudinal end portion; another longitudinal end portion; and a longitudinal middle portion through 15 which the one longitudinal end portion and the other lon¬gitudinal end portion are connected to each other, and
the one longitudinal end portion is contacted with one side of the surrounding body, and the other longitudi¬nal end portion is contacted with another side of the sur-20 rounding body, the one side and the other side being oppo¬site to each other across the longitudinal middle portion.
[0015]
In a further mode of the sealing material composition of the invention, 25 the one and other longitudinal end portions of each

7
of the sheet-like members are elongated in a direction which is inclined with respect to the longitudinal direc¬tion of the surrounding body. [0016] 5 In a still further mode of the sealing material com¬position of the invention,
the longitudinal middle portion of each of the sheet¬like members is disposed to be inclined with respect to the longitudinal direction of the surrounding body, and 0 at least one of the one and other longitudinal end portions of the sheet-like member is disposed along the longitudinal direction of the surrounding body. [0017]
The gland packing of the invention 5 contains the above-described sealing material compo¬sition.
[0018] In another mode of the gland packing of the invention, the gland packing comprises: 0 an inner core member in which the sealing material composition is used; and
yarns which are disposed in a periphery of the inner core member in a state where the yarns are twisted or braided together. 5 [0019]

8
In a further mode of the gland packing of the inven¬tion,
the surrounding body of the sealing material composi¬tion is formed by metal wires, and 5 each of the yarns comprises an expanded graphite ma¬terial , and a reinforcing material which reinforces the expanded graphite material.
[0020]
In a still further mode of the gland packing of the 10 invention,
the inner core member is 5 mass% or more and 70 mass% or less based on a total mass of the gland packing.
[0021]
In a still further mode of the gland packing of the 15 invention,
the gland packing is formed by only the sealing mate-rial composition. Effects of the Invention
[0022] 20 According to the invention, it is possible to provide a sealing material composition containing expanded graph¬ite, and which hardly causes the sheet-like members to be broken. According to the invention, furthermore, it is possible to provide a gland packing in which the sealing 2 5 property can be improved.

9
Brief Description of the Drawings
[0023]
Fig. 1 is a perspective view of a sealing material composition of an embodiment of the invention. 5 Fig. 2 is a schematic plan view of the sealing mate¬rial composition of Fig. 1.
Fig. 3 is a schematic partial sectional view of the sealing material composition of Fig. 1.
Fig. 4 is a schematic partial sectional view of the 10 sealing material composition of Fig. 1 in the case where the composition is flexed.
Fig 5 is a schematic partial sectional view of a sealing material composition of another embodiment of the invention. 15 Fig. 6 is a schematic partial sectional view of a conventional sealing material composition which is a com¬parative example.
Fig. 7 is a view showing experimental results.
Fig. 8 is a partial sectional perspective view of a 20 gland packing of a further embodiment of the invention.
Fig. 9A is a sectional view showing an example of a use state of the gland packing of Fig. 8, and Fig. 9B is a schematic perspective view of the gland packing of Fig. 9A.
Fig. 10 is a sectional view of the gland packing of 25 Fig. 8.

10
Fig. 11 is a diagram schematically showing an experi-mental apparatus.
Fig. 12 is a view of results of experiments using the experimental apparatus of Fig. 11. 5 Mode for Carrying Out the Invention
[0024]
Firstly, an embodiment of the sealing material compo¬sition of the invention will be described with reference to the drawings. 10 [0025]
Fig. 1 is a perspective view of a sealing material composition 1 of an embodiment of the sealing material of the invention, Fig 2 is a schematic plan view of the sealing material composition 1, and Fig. 3 is a schematic 15 partial sectional view of the sealing material composition 1.
[0026]
In the sealing material composition 1 (a stacked body 5 (sheet-like members 10) and surrounding body 6 which 20 will be described later), it is assumed that the direction of the arrow X in Fig. 1 is the longitudinal direction, that of the arrow Y is the short direction, and that of the arrow Z is the thickness direction (vertical direc¬tion) . In the drawings, the dimension ratios are ade-2 5 quately exaggerated for the sake of convenience in de-

11
scription, and may be sometimes different from the actual ratios.
[0027]
The sealing material composition 1 contains expanded
5 graphite as a material, is a member for forming a sealing
material, and used for producing a sealing material such
as a gland packing or a gasket. A part or whole of the
sealing material composition 1 can be used for forming a
part (for example, an inner core member) of the sealing
10 material or the whole (for example, a molded packing) of
the sealing material.
[0028]
As shown in Figs. 1 to 3, the sealing material compo¬sition 1 comprises the stacked body 5 and the surrounding 15 body 6. The surrounding body 6 is formed into a long body, and disposed so as to surround the stacked body 5. In the embodiment, the sealing material composition 1 is a string-like (long) member exhibiting a rectangular paral¬lelepiped shape, and has a longitudinal length which ena-20 bles at least one sealing material such as a gland packing or a gasket to be produced. [0029]
The stacked body 5 has a plurality of sheet-like mem¬bers 10. Each of the sheet-like members 10 is formed into 25 a tape-like (belt-like) shape by, for example, expanded

12
graphite. The sheet-like members 10 are stacked in a di¬rection which intersects with the longitudinal direction of the surrounding body 6, and placed at predetermined in¬tervals in the longitudinal direction. In the plurality 5 of sheet-like members 10, sheet-like members 10 which are adjacent to each other in the stacking direction are dis¬posed to be displaced from each other in the longitudinal direction of the surrounding body 6, in a relatively mova¬ble manner.
10 [0030]
In the embodiment, each of the sheet-like members 10 is an expanded graphite-made tape-like member in which ex-panded graphite is the main component. The sheet-like member 10 is a belt-like member which has a rectangular
15 parallelepiped shape that is substantially flat, and has an approximately constant thickness and a longitudinal length which is shorter than that of the surrounding body 6. The sheet-like members 10 may not be strictly identi¬cal in shape with one another, and may have a production
2 0 error. The sheet-like members may have any shape, as far as the shape allows the stacked body 5 to be molded. [0031]
The plurality of sheet-like members 10 are placed so as to be elongated in a substantially same direction. The
2 5 plurality of sheet-like members 10 are stacked so that the

13
stacked body 5 has a rectangular parallelepiped shape ex¬cept the both longitudinal end portions in a state where one of adjacent sheet-like members 10 is displaced by a predetermined distance from the other of the adjacent 5 sheet-like members 10 in the longitudinal of the surround¬ing body 6. [0032]
Here, the above-described direction which intersects with the longitudinal direction of the surrounding body 6,
10 i.e., the stacking direction of the plurality of sheet¬like members 10 is a direction which is inclined with re¬spect to the thickness direction that is perpendicular to the longitudinal and short directions of the surrounding body 6.
15 [0033]
In adjacent sheet-like members 10, specifically, one sheet-like member 10 and another sheet-like member 10 are stacked so that they are relatively slidable in a direc¬tion (the longitudinal direction of the surrounding body
20 6) which is substantially perpendicular to the stacking direction. Irrespective of their slidings, the stacked state of the one and other sheet-like members 10 is main¬tained by the surrounding body 6. [0034]
2 5 As shown particularly in Fig. 3, in all places where

14
a positional displacement occurs in the stacked body 5, the displacement distances G of adjacent sheet-like mem¬bers 10 (namely, the displacement distances of the one sheet-like member 10 and the other sheet-like member 10) 5 are set so as to be substantially same as one another along the longitudinal direction of the surrounding body 6 in the initial state shown in Fig. 3 so as to avoid a state wherein external force is applied to the sealing ma¬terial composition 1, and the sealing material composition
10 is flexed. [0035]
Between each pair of sheet-like members 10 which are adjacent to each other in the stacked state, a step por¬tion 11 is formed in accordance with the thickness of the
15 sheet-like member 10 of one side (or the sheet-like member 10 of the other side). The step portions 11 are formed in both upper and lower surface portions 8, 9 of the stacked body 5, respectively, and arranged along the longitudinal direction of the surrounding body 6 at substantially regu-
2 0 lar intervals. [0036]
The displacement distance G of adjacent sheet-like members 10 in the initial state is not particularly lim¬ited, and may be set so that the stacked state is main-
25 tained even when the displacement distance is increased

15
from the displacement distance G in the initial state by a relative movement (relative sliding) of the adjacent sheet-like members 10. For example, the displacement dis-tances G may be different from one another. 5 [0037]
In the embodiment, each of the sheet-like members 10 has: one longitudinal end portion 13 which is exposed in the upper surface portion 8; another longitudinal end por¬tion 14 which is exposed in the lower surface portion 9;
10 and a longitudinal middle portion 15 through which the one longitudinal end portion 13 and the other longitudinal end portion 14 are connected to each other. The one and other longitudinal end portions 13, 14 of the sheet-like member 10 are elongated in a direction which is inclined with re-
15 spect to the longitudinal direction of the surrounding body 6 so that the one longitudinal end portion 13 is con¬tacted with one side of the surrounding body 6, and the other longitudinal end portion 14 is contacted with anoth¬er side of the surrounding body 6. The one side (the side
20 of the upper surface portion 8 of the stacked body 5) and the other side (the side of the lower surface portion 9) are opposite to each other across the longitudinal middle portion 15. [0038]
25 As shown in Fig. 3, in the upper and lower surface

16
portions 8, 9 of the stacked body 5, specifically, the step portions 11 are formed by the one and other longitu¬dinal end portions 13, 14 of the sheet-like members 10. The longitudinal middle portion 15 constituting the major 5 part of each of the sheet-like members 10 has a predeter¬mined inclination angle Gl with respect to the longitudi¬nal direction of the surrounding body 6.
[0039]
Each of the sheet-like members 10 configures one lay-10 er of the stacked body 5. In the embodiment, the stacked body 5 has a structure in which seven sheet-like members 10 are stacked. The number of stacked sheet-like members 10 is not particularly limited, and may be adequately set in accordance with the thickness of each sheet-like member 15 10 or the like. It is requested to stack at least two sheet-like members 10.
[0040]
In Figs. 1 and 3, the gaps are exaggeratingly illus¬trated between adjacent sheet-like members 10. Actually, 2 0 the plurality of sheet-like members 10 are stacked so as to form substantially no gaps (see Fig. 4) , and therefore the stacked body 5 is more flattened as compared with the stacked body shown Figs. 1 and 3.
[0041] 25 In the embodiment, at least one of the one and other

17
longitudinal end portions 13, 14 of each of the sheet-like members 10 is disposed so as to be elongated along the longitudinal direction of the surrounding body 6. Specif¬ically, both the one and other longitudinal end portions 5 13, 14 are bent with respect to the longitudinal middle portion 15 so as to be elongated in substantially parallel to the longitudinal direction of the surrounding body 6. [0042]
For example, each of the sheet-like members 10 has a 10 length in the longitudinal direction of about 100 mm or more and 300 mm or less (preferably, 150 mm or more and 250 mm or less) , a length in the short direction (the di¬rection which is perpendicular to both the longitudinal direction and the thickness direction Z) of about 1 mm or 15 more and 30 mm or less (preferably, 3 mm or more and 15 mm or less), and a thickness of about 0.01 mm or more and 3.0 mm or less (preferably, 0.1 mm or more and 1.0 mm or less) [0043]
The longitudinal, short, and thickness directions of 20 the sheet-like members 10 are identical with those of the sealing material composition 1, respectively. [0044]
As shown in the figures, the surrounding body 6 is
configured so as to allow adjacent sheet-like members 10
25 (the stacked body 5) to be relatively moved in the longi-

18
tudinal direction of the surrounding body 6, while main¬taining the stacked state of the sheet-like members. In the embodiment, the surrounding body 6 has a tubular shape in which the stacked body 5 can be inserted in the longi-5 tudinal direction of the surrounding body. The both lon¬gitudinal end portions of the surrounding body 6 are con¬figured so as to be able to have a released state where those of the stacked body 5 are exposed. [0045]
10 The surrounding body 6 is a net-like member having a mesh structure, and elongated in the longitudinal direc¬tion in a state where the surrounding body 6 is substan¬tially in contact with the surface layers of the stacked body 5 which is surrounded by the surrounding body 6. The
15 surrounding body 6 is formed so that its external shape in a state where the surrounding body 6 surrounds the stacked body 5 substantially forms the external shape of the seal¬ing material composition 1. The surrounding body 6 is configured by using wire members 17 which are knitted by
20 an adequate knitting method (for example, the loop-forming knitting method) , or which are braided by an appropriate braiding method. [0046] Although, in the embodiment, the surrounding body 6
25 comprises the wire members 17 which are twisted at prede-

19
termined angle with respect to the longitudinal direction, the surrounding body is not limited to this, and may com¬prise wire members which are elongated in a direction that is approximately identical with the longitudinal direction. 5 The intervals of the wire members 17 may be uneven as shown in the figures, or approximately even. [0047]
As the wire members 17, for example, useful are: met¬al wires configured by a nickel alloy, or an alloy or the
10 like in which iron is the main component, such as stain¬less steel; a natural resin such as natural rubber; a syn¬thetic resin; a fluorine resin such as polytetrafluoroeth-ylene; natural or synthetic resin fibers; and the like. In the embodiment, metal wires are used as the wire mem-
15 bers 17. The wire members 17 are round wires having a di¬ameter of, for example, about 0.01 mm or more and 1 mm or less. Actually, the surrounding body 6 surrounds the stacked body 5 which is more flattened as compared with the stacked body shown in Figs. 1 and 3 so that gaps are
20 not substantially formed between adjacent sheet-like mem¬bers 10 as described above. [0048]
In this configuration, when the sealing material com¬position 1 is flexed and curved in order to, for example,
25 produce a sealing material by using the sealing material

20
composition 1, or convey the sealing material composition 1 while winding the composition around a round rod member, each of adjacent sheet-like members 10 can be slid in the longitudinal direction of the surrounding body 6 so that 5 the sheet-like members are positionally displaced from each other. [0049]
In the sealing material composition 1, namely, adja¬cent sheet-like members 10, i.e., one sheet-like member 10
10 and the other sheet-like member 10 can be relatively moved along the longitudinal direction of the surrounding body 6 while the adjacent sheet-like members 10 are flexed. In this case, moreover, the stacked state of the adjacent sheet-like members 10 can be maintained.
15 [0050]
As shown in Fig. 4, while maintaining the stacked state of the plurality of sheet-like members 10, specifi¬cally, the one longitudinal end portions 13 can be slid as indicated by the arrows 18 in the upper (on the side of
20 the outer circumferential surface) surface portion 8 of the stacked body 5, and the other longitudinal end por¬tions 14 can be slid as indicated by the arrows 19 in the lower (on the side of the inner circumferential surface) surface portion 9 of the stacked body 5.
25 [0051]

21
Therefore, it is possible to, when an external force is applied to the sealing material composition 1 in order to curve it, block a portion which is sharply bent, from being formed in the sealing material composition 1, and 5 hence it is further possible to prevent one of the sheet¬like members 10 from being broken because of such a bent portion. Consequently, a defect which may cause the per¬formance to be lowered can be prevented from occurring in the sealing material composition 1.
10 [0052]
The sealing material composition 1 of the invention is not limited to the above-de scribed embodiment. As shown in Fig. 5, for example, sheet-like members 20 may have a longitudinal length which is shorter than that of
15 the sheet-like members 10, and an inclination angle 92 which is larger than the inclination angle 91 in the em¬bodiment. Although not illustrated, the sheet-like mem¬bers 20 may have a longitudinal length which is longer than that of the sheet-like members 10, and an inclination
2 0 angle which is smaller than the inclination angle 91, with respect to the longitudinal direction of the surrounding body 6.
[0053] An experiment on the flexibility of the the sealing
25 material composition confirmed that the above-described

22
effects are attained. The experiment was performed by the following method. In the experiment, as sheet-like mem¬bers, Example 1 of the invention. Example 2 of the inven¬tion, and Comparative Example 1 having a structure which 5 is similar to that of a conventional sheet-like member were prepared. Moreover, first and second round rod mem¬bers were prepared. [0054] Example 1 has a structure similar to that of the
10 sealing material composition 1. The plurality of sheet¬like members 10 in the stacked body 5 have a longitudinal length of about 200 mm, and constitute a structure in which seven layers of sheet-like members are stacked. The plurality of sheet-like members 10 are placed with the
15 displacement distances G which enable the sheet-like mem¬bers to form five step portions 11 at intervals of 10 cm in the longitudinal direction of the surrounding body 6. [0055] Example 2 has a structure similar to that of the
20 sealing material composition shown in Fig. 5. The plural¬ity of sheet-like members 20 in the stacked body 5 have a longitudinal length of about 100 mm, and constitute a structure in which seven layers of sheet-like members are stacked. The plurality of sheet-like members 20 are
25 placed with the displacement distances G which enable the

23
sheet-like members to form seven step portions 11 at in¬tervals of 10 cm in the longitudinal direction of the sur¬rounding body 6. [0056] 5 Comparative Example 1 has a structure similar to that of the conventional sealing material composition shown in Fig. 6. A plurality of fibrous members 30 are filled into a surrounding body 32 so as to be randomly arranged. The fibrous members 30 are placed so that a step portion is 10 not formed in the vicinity of the surrounding body 32, and many (a large area) gaps are produced in the surrounding body 32.
[0057]
The first round rod member is configured so that Ex-15 ample 1, Example 2, and Comparative Example 1 can be wound around the member over the whole circumference, and has a diameter of 10 mm. The second round rod member is config¬ured so that Example 1, Example 2, and Comparative Example 1 can be wound around the member over the whole circumfer-20 ence, and has a diameter of 30 mm. [0058]
Each of Example 1, Example 2, and Comparative Example
1 was wound around each of the first and second round rod
members over a substantially whole circumference while be-
25 ing flexed and curved. Thereafter, each of Example 1, Ex-

24
ample 2, and Comparative Example 1 was detached from the first and second round rod members, and the states of the sheet-like members 10, 20 and the fibrous members 30 were checked. 5 [0059]
Fig. 7 shows the results of the experiment. In Exam¬ple 1 and Example 2, no breakage was observed (in the fig¬ure, this is indicated by the symbol "O") in all of the sheet-like members 10, 20. In Comparative Example 1, by
10 contrast, breakage extending over the all layers was ob-served (in the figure, this is indicated by the symbol "x") in two places in the longitudinal direction of the surrounding body 32. [0060]
15 In the embodiment, as described above, the sheet-like members 10 are elongated in the direction inclined with respect to the longitudinal direction of the surrounding body 6. When a bending action is applied to the sealing material composition 1, therefore, adjacent sheet-like
20 members 10 can be smoothly slid. Consequently, it is pos¬sible to cause breakage to more hardly occur in the plu-rality of sheet-like members 10. [0061] In the embodiment, the one and other longitudinal end
25 portions 13, 14 of the sheet-like members 10 are disposed

25
so as to be elongated along the longitudinal direction of the surrounding body 6. Therefore, the end portions 13, 14 are not projected from the mesh portion of the sur¬rounding body 6 toward the outside. Consequently, the one 5 and other longitudinal end portions 13, 14 can be prevent¬ed from being broken by collision with an installation ar¬ticle or the like which is disposed in the outside. [0062]
Next, an embodiment of the gland packing of the in-10 vention containing the above-described sealing material composition 1 will be described with reference to the drawings.
[0063]
Fig. 8 is a partial sectional perspective view of a 15 gland packing 51 which is an embodiment of the gland pack¬ing of the invention, Fig. 9A is a sectional view showing an example of a use state of the gland packing 51, Fig. 9B is a schematic perspective view of the gland packing 51 of Fig. 9A, and Fig. 10 is a sectional view of the gland 20 packing 51. In these figures, for the sake of convenience of description, the gland packing 51 is diagrammatically illustrated. [0064]
As shown in Fig. 8, the gland packing 51 is a string-2 5 like sealing material configured by using the sealing ma-

26
terial composition 1. As shown in Fig. 9A, the gland packing 51 is configured so as to be able to seal a gap between an inner sealed portion (a shaft member of a pre¬determined apparatus) 101 and outer sealed portion (a sta-5 tionary portion of the predetermined apparatus) 102 which are opposed to each other during use, in a state where the gland packing 51 is compressed in a direction (the axial direction of the shaft member) that is substantially per¬pendicular to the opposing direction of the portions.
10 [0065]
In the embodiment, as shown in Figs. 8 and 10, the gland packing 51 comprises an inner core member 53 config¬ured by the sealing material composition 1. The gland packing 51 further comprises a plurality of yarns 54 which
15 are disposed in the periphery of the inner core member 53 as other sealing material compositions in a state where the yarns are twisted or braided together. The gland packing 51 is formed into a string-like shape having a predetermined longitudinal length.
20 [0066]
When the gland packing 51 is to be used, as shown in Fig. 9B, for example, the packing is firstly formed or compression molded into a ring-like shape which corre¬sponds to the inner sealed portion 101. As shown in Fig.
25 9A, then, the gland packing 51 is stuffed into a stuffing

27
box 103 of the outer sealed portion 102. The stuffing box 103 is located in the periphery of the inner sealed por¬tion 101. Thereafter, the gland packing 51 is held in a state where the packing is tightened by a gland (packing 5 gland) 104. [0067]
In the case where, as shown in Fig. 9B, the gland packing 51 is formed into a ring-like shape which corre¬sponds to the inner sealed portion 101, a direction inter-
10 secting with the longitudinal direction of the surrounding body 6 of the sealing material composition 1 constituting the inner core member 53, i.e., the stacking direction of the plurality of sheet-like members 10 (the stacked body 5) may be set as the vertical direction (substantially co-
15 incident with a radial direction of the inner sealed por¬tion 101) in Fig. 10, the lateral direction (substantially coincident with the axial direction of the inner sealed portion 101) in Fig. 10, or a diagonal direction in Fig. 10. Preferably, the stacking direction is set as the lat-
2 0 eral direction in Fig. 10 (in other words, the sheet-like members 10 are arranged in a vertical direction (a direc¬tion which is substantially perpendicular) with respect to the axial direction of the inner sealed portion 101). [0068]
25 In the embodiment, as shown in Figs. 8 and 10, the

28
yarns 54 are disposed in a plural number, i.e., 16 yarns. The yarns 54 are elongated along the inner core member 53 in the longitudinal direction of the member, and twisted or braided together so as to be bundled (disposed) around 5 the inner core member 53, thereby forming the string-like gland packing 51 having an elongated shape. [0069]
The yarns 54 are 16-strand hollow braided so as to cover the inner core member 53. Although, in the embodi-
10 ment, the yarns 54 which constitute the gland packing 51 together wi th the inner core member 5 3 have the configura-tion in which the 16-strand hollow braiding using 16 yarns is employed, the configuration of the yarns is not limited to this. For example, the yarns may have a configuration
15 in which the 4-strand square braiding using four yarns or the 8-strand square braiding using eight yarns is employed, [0070]
The yarns 54 are formed to be thinner than the string-like inner core member 53. In the embodiment, (the
20 content rate of) the inner core member 53 in the gland packing 51 is set so as to be 5 mass% or more and 70 mass% or less based on the total mass of the gland packing 51, and therefore the yarns 54 have a content rate (mass ra¬tio) corresponding to the content rate of the inner core
2 5 member.

29
[0071]
Although the detail will be described later with ref¬erence to Fig. 12, when the content rate of the inner core member 53 in the gland packing 51 is less than 5 mass%, 5 the rate (the remaining percentage of the tightening force) at which the initial tightening force remains after completion of tightening is lowered (in the specification, this phenomenon is also referred to as "stress relaxa¬tion") . The sealing property is lowered with occurrence
10 of the stress relaxation, and therefore it is necessary that the content rate of the inner core member 53 in the gland packing 51 is 5 mass% or more. One of causes of the phenomenon that the initial tightening force is not main¬tained and the stress relaxation occurs is that the gland
15 packing 51 itself protrudes through a gap of the apparatus, and the volume of the gland packing 51 is reduced. When the content rate of the inner core member 53 in the gland packing 51 exceeds 70 mass%, by contrast, the rate of the yarns 54 with respect to the gland packing 51 is increased,
20 and the amount of a lubricant becomes inadequate, whereby the sealing property is lowered. In order to prevent this from occurring, it is necessary to set the content rate of the inner core member 53 in the gland packing 51 to 70 mass% or less.
25 [0072]

30
More preferably, the content rate of the inner core
member 53 in the gland packing 51 is set to 5 mass% or
more and 50 mass% or less based on the total mass of the
gland packing 51, and, further preferably, is set to 20
5 mass% or more and 50 mass% or less. When the content rate
of the inner core member 53 in the gland packing 51 is set
to 20 mass% or more and 50 mass% or less, the leakage
amount can be further reduced, and a remaining percentage
of the tightening force which is higher than a predeter-
10 mined value can be easily ensured.
[0073]
In the above, it is assumed that all of the yarns 54 have a substantially same structure. Alternatively, for example, a part of the yarns 54 may have a structure which 15 is different from that of the other yarns 54. [0074]
In the embodiment, as shown in Fig. 10, each of yarns 54 is configured by an expanded graphite material 151, a lubricant, and a reinforcing material 152 for reinforcing 20 the expanded graphite material 151. The expanded graphite material 151 is formed in an elongated shape. The lubri¬cant is disposed so as to be generally interposed between adjacent ones of the yarns 54. An example of the lubri¬cant is fluorine resin powder (PTFE dispersion or the 25 like).

31
[0075]
The reinforcing material 152 is configured by using at least one wire member for reinforcing outwardly or in¬wardly the expanded graphite material 151. In the embodi-5 ment, the reinforcing material 152 reinforces outwardly the expanded graphite material 151, and is formed to be thinner than the expanded graphite material 151. Examples of the at least one wire member constituting the reinforc¬ing material 152 are a metal wire of a nickel alloy,
10 stainless steel, or the like, and a non-metal wire config-ured by organic fibers (cotton or the like) or inorganic fibers (carbon fibers or the like). [0076] In the case where an outward reinforcement structure
15 in which the reinforcing material 152 reinforces outwardly the expanded graphite material 151 is employed as in the embodiment, the expanded graphite material 151 is config¬ured by a plurality of fibrous expanded graphites, and the reinforcing material 152 is a tubular member which is
20 formed by the loop-forming knitting method using at least one wire member, and into which the expanded graphite ma¬terial 151 is filled. The outward reinforcement structure is not limited to this. For example, the outward rein¬forcement structure may be formed so that the expanded
25 graphite material 151 is folded in mountain folds and val-

32
ley folds, or mountain folds, or valley folds, and the re-inforcing material 152 is a braided body which is config¬ured by the above-described at least one wire member, and which covers the expanded graphite material 151 in the
5 folded state. [0077]
In place of the outward reinforcement structure, an inward reinforcement structure in which the reinforcing material 152 reinforces inwardly the expanded graphite ma-
0 terial 151 may be employed. In this case, for example, an inward reinforcement structure may be employed in which the reinforcing material 152 is disposed so to be elongat¬ed along the expanded graphi te material 151, and the ex¬panded graphite material 151 in this state is formed into
5 a string-like body in which the expanded graphite is fold¬ed in mountain folds and valley folds, or mountain folds, or valley folds so as to envelop the reinforcing material 152. Alternatively, an inward reinforcement structure may be employed in which the reinforcing material 152 is dis-
0 posed so to be elongated along the expanded graphite mate-rial 151, and the expanded graphite material 151 in this state is formed into a string-like body in which the ex¬panded graphite material is twisted. [0078]
5 According to the configuration, in the case where,

33
when the gland packing 51 is to be used, the gland packing is curved into a ring-like shape in order that the packing is placed between the inner sealed portion and the outer sealed portion, i.e., in order that the packing is stuffed 5 into a stuffing box of a predetermined apparatus, the in¬ner core member 53 (the sealing material composition 1) of the gland packing 51 enables adjacent sheet-like members 10 to be slid in the longitudinal direction of the sur¬rounding body 6 so that the sheet-like members are posi-
10 tionally displaced from each other, as described above. [0079]
While preventing the expanded graphite of the sheet¬like members 10 from being partly broken, therefore, it is possible to improve the flexibility of the inner core mem-
15 ber 53, i.e., that of the gland packing 51 using the inner core member. When the gland packing 51 is curved, conse¬quently, the lowering of the sealing property of the inner core member 53 which is due to partial breakage of the ex¬panded graphite of the sheet-like members 10 can be sup-
20 pressed from occurring. Therefore, the sealing property of the gland packing 51 can be improved. [0080]
In the case where, when the gland packing 51 is to be used as shown in, for example, Fig. 10, the gland packing
25 51 is formed into a ring-like shape so that the stacking

34
direction of the sheet-like members 10 in the inner core
member 53 coincides with the axial direction of the inner
sealed portion, the stacked sheet-like members 10 can be
held in a state where the sheet-like members are folded in
5 a complex manner, and the sealing property of the inner
core member 53 can be improved. Therefore, the sealing
property of the gland packing 51 can be further improved.
[0081]
In the embodiment, the inner core member 53 in which
10 a lubricant is not used is employed, and hence the used amount of a lubricant which is a cause of the stress re¬laxation can be reduced in the gland packing 51. There¬fore, the stress relaxation can be suppressed, and hence the lowering of the tightening force due to the gland can
15 be suppressed. As a result, a gap is hardly formed be¬tween the gland packing 51 and the inner surface of the stuffing box, and an excellent sealing property can be en¬sured for a long period of time. [0082]
20 When the following experiment was performed, it was confirmed that the use of the gland packing of the inven¬tion can suppress reduction of the leakage amount of the fluid per unit time (the sealing property), and the lower¬ing of the remaining percentage of the tightening force
25 (the stress relaxation). In the experiment, Examples 3 to

35
7 of the invention were prepared, and Comparative Examples 2 and 3 were prepared. Moreover, an experimental appa¬ratus 70 corresponding to the examples and the comparative examples was prepared. 5 [0083]
Example 3 is a gland packing which comprises: an in¬ner core member having a mass ratio of the stacked body (expanded graphite) : the surrounding body (metal wires) = 85:15; and a plurality of yarns having a mass ratio of the
10 expanded graphite material the reinforcing material (metal wire) : the lubricant = 80:10:10, and which has a mass ratio of the inner core member : the plurality of yarns = 5:95. [0084]
15 Example 4 is a gland packing which comprises: an in¬ner core member having a mass ratio of the stacked body (expanded graphite) : the surrounding body (metal wires) = 85:15; and a plurality of yarns having a mass ratio of the expanded graphite material the reinforcing material
20 (metal wire) the lubricant = 80:10 :10, and which has a mass ratio of the inner core member : the plurality of yarns = 20:80. [0085] Example 5 is a gland packing which comprises: an in-
25 ner core member having a mass ratio of the stacked body

36
(expanded graphite) : the surrounding body (metal wires) =
85:15; and a plurality of yarns having a mass ratio of the
expanded graphite material the reinforcing material
(metal wire) the lubricant = 80:10:10, and which has a
5 mass ratio of the inner core member the plurality of
yarns = 30:70.
[0086]
Example 6 is a gland packing which comprises: an in¬ner core member having a mass ratio of the stacked body
10 (expanded graphite) : the surrounding body (metal wires) =
85:15; and a plurality of yarns having a mass ratio of the
expanded graphite material : the reinforcing material
(metal wire) : the lubricant - 80:10:10, and which has a
mass ratio of the inner core member : the plurality of
15 yarns = 50:50. [0087]
Example 7 is a gland packing which comprises: an in¬ner core member having a mass ratio of the stacked body (expanded graphite) : the surrounding body (metal wires) =
20 85:15; and a plurality of yarns having a mass ratio of the
expanded graphite material the reinforcing material
(metal wire) : the lubricant = 80:10:10, and which has a
mass ratio of the inner core member : the plurality of
yarns = 70:30.
25 [0088]

37
Comparative Example 2 is a gland packing which com¬prises: an inner core member having a mass ratio of the stacked body (expanded graphite) : the surrounding body (metal wires) = 85:15; and a plurality of yarns having a 5 mass ratio of the expanded graphite material the rein¬forcing material (metal wire) : the lubricant = 80:10:10, and which has a mass ratio of the inner core member : the plurality of yarns = 4:96. [0089] 10 Comparative Example 3 is a gland packing which com-prises: an inner core member having a mass ratio of the stacked body (expanded graphite) : the surrounding body (metal wires) — 85:15; and a plurality of yarns having a mass ratio of the expanded graphite material : the rein-15 forcing material (metal wire) : the lubricant = 80:10:10, and which has a mass ratio of the inner core member : the plurality of yarns = 71:29. [0090]
As shown in Fig. 11, the experimental apparatus 70 2 0 comprises a hydraulic unit 72 including a hydraulic cylin¬der 71, a first load transducer 73 for measuring the axial load, a second load transducer 74 for measuring the tight¬ening force, a packing box 75, a heater 76, and a control¬ler 77. A sealing device 80 such as shown in Fig. 9A can 25 be incorporated in the packing box 75.

38
[0091]
The experimental apparatus 70 is configured so that a
fluid to be sealed is introduced into a box basal portion
82 through an inlet path 81, the temperature of the intro-
5 duced fluid to be sealed is raised by the heater 76, the
fluid to be sealed is then supplied to the sealing device
which is incorporated in the packing box 75, and the fluid
that leaks from the sealing device to which the fluid to
be sealed is supplied is discharged from a box main por-
10 tion 83 through a discharge path 84.
[0092]
The experimental apparatus 70 further comprises: a pressure gauge 86 for detecting the pressure of the fluid to be sealed which is supplied to the sealing device; a 15 pressure transducer 87 for transducing the detected pres¬sure to a control signal; and a temperature sensor 88 for detecting the temperature of the fluid to be sealed. The experimental apparatus 70 further comprises a load cell (not shown) for measuring the remaining percentage of the 2 0 tightening force, in the sealing device. [0093]
Referring to Fig. 9A, the sealing device comprises: the stuffing box 103 of the outer sealed portion 102 (the packing box 75) ; gland packings (members which are placed 2 5 like the gland packing 51) which are stuffed into the

39
stuffing box 103 in a state where the packings surround the inner sealed portion (stem) 101; and the gland (pack¬ing gland) 104 for tightening the gland packings in the state where the gland packings are stuffed into the stuff-5 ing box 103. [0094]
The sealing device is configured so that, when bolts which are disposed on the side of the gland 104 are fas¬tened, the plurality of gland packings (of one of Examples 10 3 to 7, and Comparative Examples 2 and 3) that are ar¬ranged in the axial direction of the stem 101 are pressed in the axial direction of the stem 101, and a sealing por¬tion that seals the gap between the inner surface of the stuffing box 103 and the outer surface of the stem 101 is 15 formed.
[0095]
In the experiment, firstly, the gland packings of Ex¬amples 3 to 7 and Comparative Examples 2 and 3 are com¬press-molded into a ring-like shape corresponding to the 20 stem 101. Then, the plurality of gland packings of one of Examples 3 to 7 and Comparative Examples 2 and 3 are dis¬posed in the sealing device so as to surround the stem 101 Next, the sealing device comprising the gland packings is incorporated in the packing box 75. 25 [0096]

40
Then, the temperature of the fluid to be sealed which has been introduced into the box basal portion 82 through the inlet path 81 is raised by the heater 76. Next, the fluid to be sealed in which the temperature has been 5 raised is supplied from the box basal portion 82 to the sealing device that is incorporated in the packing box 75. When the supply of the fluid to be sealed is to be sup¬plied, the hydraulic cylinder 71 of the hydraulic unit 72 is driven, thereby causing the stem 101 to be reciprocally 10 slid.
[0097]
In the experimental apparatus 70, during the above,
the leakage amount (the leakage amount per unit time) of
the fluid from the discharge path 84 is measured, the re-
15 maining percentage of the tightening force is measured by
the load cell, and the measured values are stored in the
controller 77. The pressure and temperature of the fluid,
the tightening force applied to the sealing device (gland
packings) , and the axial load acting on the stem 101 are
2 0 measured, and the measured values are collected in the
controller 77 to be stored therein.
[0098]
The conditions of the experiment using the experi¬mental apparatus 70 are as follows. In Examples 3 to 7 2 5 and Comparative Examples 2 and 3, each of the gland pack-

41
ings which are compress-molded into a ring-like shape has dimensions of 37 (outer diameter) x t6.4 (height), the liquid temperature is 400°C, and the liquid pressure is 15.5 MPa. 5 [0099]
According to the experiment, the experimental results shown in Fig. 12 were obtained. From the experimental re¬sults shown in Fig. 12, it was revealed that, in each of Examples 3 to 7, the leakage amount (the leakage amount
10 per unit time) from the discharge path 84, and the lower¬ing of the remaining percentage of the tightening force (stress relaxation) can be suppressed, and are within pre¬determined reference values (in the figure, this is indi¬cated by the symbol "O") . Namely, it became apparent that
15 the examples have an effect that the leakage amount (seal¬ing property) of the fluid per unit time, and the lowering of the remaining percentage of the tightening force can be suppressed, i.e., an effect that the sealing property can be improved.
20 [0100]
From the experimental results shown in Fig. 12, it was revealed that, in Comparative Example 2, it is diffi¬cult to suppress the lowering of the remaining percentage of the tightening force, and the remaining percentage is
25 deviated from the predetermined reference values (in the

42
figure, this is indicated by the symbol "x"). Moreover, it was revealed that, in Comparative Example 3, it is dif¬ficult to suppress the leakage amount (the leakage amount per unit time) from the discharge path 84, and the leakage 5 amount is largely deviated from the predetermined refer¬ence values (in the figure, this is indicated by the sym¬bol "x"). Namely, it became apparent that, in a configu¬ration such as that of Comparative Example 2 or 3, the im¬provement of the sealing property cannot be expected.
10 [0101]
Although, in the embodiment, the gland packing of the invention is configured by the inner core member 53 (the sealing material composition 1) and the yarns 54, the con-figuration of the gland packing is not limited to this.
15 The gland packing may be formed by only the sealing mate¬rial composition 1 without using the yarns 54. [0102]
Obviously, numerous modifications and variations of the present invention are possible in light of the above
20 teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
[0103] 1 sealing material composition
25 5 stacked body

43
6 surrounding body
10 sheet-like member
13 one longitudinal end portion of sheet-like member
14 other longitudinal end portion of sheet-like member
15 longitudinal middle portion of sheet-like member
51 gland packing
53 inner core member
54 yarn

151 expanded graphite material
152 reinforcing material