JP5620140B2 - Cap manufacturing method suitable for retort sterilization - Google Patents

Description

The present invention relates to a manufacturing method of relates to the method of manufacturing a cap for use in containers to be retort sterilization, particularly liners for tightly sealing the interior of the capping.

  Screw-type caps are used for containers such as metal bottle-shaped cans, and this type of container is highly convenient as a container because it can be re-sealed by attaching the cap again after opening. . In addition, most of the contents in this type of container are beverages. Therefore, in order to seal the opening (so-called mouth) of the container in a liquid-tight state, the inner surface of the cap is a liner that adheres to the mouth. Is provided.

  Since the liner seals the mouth of the container, it needs to be in close contact with the mouth. Therefore, conventionally, when the cap is attached to the mouth of the container, the liner is positively attached to the mouth of the container. It is closely attached to. Examples thereof are described in Patent Documents 1 to 4 and the like. Specifically, a cap shell having a top plate portion and a cylindrical skirt portion formed continuously around the top portion is integrally formed of a metal plate such as an aluminum alloy, and the top plate portion A synthetic resin liner is provided on the periphery of the inner surface, and the outer periphery of the liner provided on the inner surface is formed by drawing the periphery of the top plate with the cap shell attached to the mouth of the container. The side portion is brought into close contact with the outer peripheral surface of the curl portion formed at the upper end portion of the mouth portion.

  By applying the drawing to the cap shell in this way, a load is applied to the curled portion, so it is necessary to prevent deformation of the curled portion due to the load. For example, in the invention described in Patent Document 1, the outer peripheral portion of the liner And forming an inner rib on the inner side of the curled portion and an outer rib on the outer peripheral surface of the curled portion, and inserting the top of the curled portion between the ribs. And the recessed part formed in the inner wall surface (surface which contacts a curl part) in each rib is made into what is called a mountain shape. Therefore, in the invention described in Patent Document 1, it is supposed that the load applied to the curled portion can be reduced and the deformation thereof can be prevented. In addition, according to the invention of Patent Document 1, it is said that the sealing performance of the container mouth portion can be sufficiently secured and the cap can be opened and closed smoothly. Furthermore, in the invention described in Patent Literature 2, the curl portion is deformed by a load when the corner portion of the cap shell is drawn by configuring the liner so as to be spaced apart from the outer peripheral surface of the curl portion. I try to prevent that.

  On the other hand, since the liner is deformed as the corner portion of the cap shell is drawn, it is necessary to maintain hermeticity without forming a gap with the curled portion even after such deformation. Therefore, for example, in the invention described in Patent Document 3, the outer peripheral end of the liner is extended to the cylindrical portion opening end from the top portion on the top side of the Nar valley. Therefore, the portion on the outer peripheral side of the ring-shaped convex portion that fits inside the curl portion of the liner is a substantially flat collar portion. Moreover, in the invention described in Patent Document 4, an annular recess that extends continuously in the circumferential direction is formed above the knurled portion.

  Furthermore, the properties required for the liner are not limited to the above-described sealing property and openability, and it is required to maintain a sealed state even when an impact force is applied to the cap due to dropping or the like. Thus, for example, Patent Document 5 discloses a liner whose composition is specified so as to improve the drop sealing property in addition to the heat and air tightness and the plug-opening property by enhancing the stretchability.

JP 2001-139053 A Japanese Patent Laid-Open No. 2003-175972 JP 05-201459 A JP 09-95354 A Japanese Patent No. 4319594

  In the inventions described in Patent Documents 1 to 4 described above, the shape of the liner is devised so as to achieve the object in each invention. It is difficult to satisfy each of these characteristics sufficiently. On the other hand, the invention described in Patent Document 5 is a heat-resistant liner that specifies the composition of the liner and is excellent in elongation, and can improve each characteristic of heat-resistant airtightness, plug-opening property, and drop-sealing property. it can. However, since the liner having the composition described in Patent Document 5 is excellent in elongation, when it has a general shape as described in Patent Documents 1 to 4, the liner has a large outer peripheral surface. It becomes a factor that increases the opening torque due to the wrapping shape, or it is partially peeled off from the inner surface of the corner of the cap shell to create a gap, or it breaks or breaks when it receives an impact due to dropping etc. There is a possibility that cracks may occur, and there is still room for improvement in order to obtain a liner that takes advantage of the characteristics of the composition described in Patent Document 5.

The present invention has been made by paying attention to the above technical problems, and among the synthetic resins having the composition described in Patent Document 5, the resin having further specified properties is used, and the heat and air tightness is of course. it is an object to provide a method of manufacturing a cap having an excellent liner cap removal properties and fall sealability.

To achieve the above object, the present invention is the peripheral portion of the inner surface side of the front SL top plate portion of the cap shell example Bei a skirt portion depending from the periphery of the top plate and the top plate portion, a flat portion which longitudinal section the opening end of the mouth portion of the container comes into contact with the top of the mosquito Lumpur portion formed in a substantially circular shape, ra an inner rib abuts on an inner peripheral surface of the curled portion is formed integrally subjected to INA chromatography, by capped with the cap shell 該Ra Ina over has been performed in the mouth, before Symbol said draw forming the boundary position of the top plate portion and the skirt portion flat portion and the front Stories Oite a car pole tip to the method of manufacturing a cap suitable for Relais Toruto sterilization is tightly dressed, the liners are, (a) 230 hydrogenated styrene / conjugated diene which the load is not flow at 21.18N at ℃ block copolymer and 30 to 5 0 mass%, (B) Liquid paraffin 35-5 0 quality % And a 5 to 3 0 wt% (C) a polypropylene resin, (D) a silicone oil 0. (E) 0.1 to 20 parts by mass of fine powder talc having an average particle diameter of 0.1 to 10 μm is contained with respect to 100 parts by mass of the resin composition containing 2 % by mass or more, and the measurement temperature is 25 ° C. 50% compression stress at 196 N / cm ^{2 to} 490 N / cm ² , (50% compression stress at 130 ° C.) / (50% compression stress at 25 ° C.) ≧ 0.3, after 70% compression at 130 ° C. recovery ratio of 60% or more, and the elongation at 130 ° C. is formed as a material of the composition is 100% or more, when subjected to pre-Symbol liner on the inner surface of the top plate portion, the thickness of the front Symbol flats 80% to 150% of the outer radius of the front Symbol the curled portion, prior Kitaira Tan portion outer peripheral radius of the front Symbol curled portion in the radial direction length projecting outwardly of the opening portion from the outer peripheral surface of the curled portion the molding to 0% to 65%, and the pre-Symbol inner Li blanking, the flat portion smell , Parallel as well as shape formed to protrude from the position of the inner circumferential side annular than the center of the curled portion around the central axis in the opening, the outer peripheral surface of the inner ribs to the central axis of the front Symbol mouth and a tapered surface inclined at an angle range of 15 ° to 45 ° relative to such axis, and the mouth portion thickness measured in the radial direction of the boundary portion between the flat portion of the front Symbol in ribs 50% to 150% of the outer radius of the front Symbol curled portion, by forming a protruding length from the flat portion of the front Symbol inner rib 60% to 150% of the outer radius of the front Symbol curled portion, the compression of the flat portion the amount is a manufacturing method you wherein said drawing child to be 60% to 90% in each of the radially outwardly of the top side and the mouth portion of the curl portion.

  According to the present invention, since the liner is formed using the above composition as a raw material, when the drawing is applied to the boundary portion between the top plate portion and the skirt portion in order to adhere to the curled portion, the liner is the curled portion. It adheres to the outer peripheral surface of this without gaps, and good sealing properties can be obtained. In particular, when the recovery rate after compressing 70% at 130 ° C. is 60% or more and the elongation rate at 130 ° C. is 100% or more, the container falls and impact force acts on the cap. However, it is difficult for the liner to crack or crack, and the fall sealability can be improved. In addition, by defining the dimensions of each part of the liner as described above, the liner after the above-described drawing molding does not excessively wrap around the outer peripheral surface of the curled part, thereby suppressing an increase in the opening torque. Thus, the opening performance can be improved. In particular, by defining the thickness of the flat part and the compression amount by drawing as described above, it is possible to sufficiently increase the shock absorption capacity, suppress the increase in the opening torque, and further improve the sealing performance. can do. In general, according to the present invention, it is possible to obtain a cap having a liner excellent in openability and drop-sealing performance as well as heat and air tightness.

It is a fragmentary sectional view which shows the shape of the liner before the drawing of a corner part. It is a fragmentary sectional view which shows the shape of the liner after the drawing of a corner part. It is a fragmentary sectional side view which shows the left half of an example of the cap shell which concerns on this invention in a cross section. It is a figure which shows the test piece of the elongation rate about the composition which is a raw material of a liner.

  The cap of the present invention is a cap used to seal the mouth of a container to be sterilized by retort sterilization at 130 ° C. for about 30 minutes. In particular, the mouth of the container has a substantially circular cross section. This is a cap that is curled and has a synthetic resin liner on its inner surface that is in close contact with the curled portion. Furthermore, in order to enable resealing of the container, the container is configured to be attached to the mouth and neck of the container by a screw. The screw is so-called roll-on molded. Therefore, a cap shell that is not drawn is used to make the screw part or liner closely contact the mouth part, and the above liner is formed on the inner surface. It is provided and attached to the mouth and neck of a container such as a bottle-shaped can, and in that state, drawing and roll-on formation of the screw portion are performed.

  An example of the cap shell is shown in FIG. The cap shell shown here is formed by press working using a conventionally known metal plate for a metal cap such as an aluminum alloy plate or a surface-treated steel plate, and has a disk-shaped top plate portion 1 and A cylindrical skirt portion 2 is integrally formed in a cup shape. In addition, after the drawing, a knurl portion 3 in which the concave portions 3a and the convex portions 3b are alternately repeated over the entire circumferential direction is formed at the upper portion of the skirt portion 2, and the knurl portion 3 has an upper portion of the concave portion 3a. A vent slit 4 extending in the circumferential direction is formed so as to quickly discharge the gas inside the container when the container is opened. A rupture line 5 is formed at the lower portion of the skirt portion 2 by a plurality of bridges 5 a and slits 5 b extending in the circumferential direction. The skirt portion 2 is formed by a main portion above the rupture line 5 and a rupture line 5. Is also divided into a lower pilfer proof band portion 6.

A sealing liner 7 made of synthetic resin is formed on the inner surface of the top plate portion 1 of the cap shell. The material was specially developed as a heat-resistant retort liner material, and more specifically, among the compositions described in the aforementioned Japanese Patent No. 4319594, the restoration rate after compression Those having excellent elongation are used. That is, the composition is
(A) Hydrogenated styrene / conjugated diene block copolymer 30 to 50% by mass that does not flow at 230 ° C. and a load of 21.18 N;
(B) liquid paraffin 35 to 50% by mass ;
(C) 5 to 30% by mass of a polypropylene resin,
(D) Silicone oil 0. With respect to 100 parts by mass of the resin composition containing 2 % by mass or more,
(E) 0.1 to 20 parts by mass of fine powder talc having an average particle size of 0.1 to 10 μm, and “50% compressive stress at a measurement temperature of 25 ° C.” is 196 N / cm ^{2 to} 490 N / cm ² , ( 50% compressive stress at 130 ° C.) / (50% compressive stress at 25 ° C.) ≧ 0.3, in particular, “the restoration rate after 70% compression at 130 ° C. is 60% or more, and A composition having an elongation at 130 ° C. of 100% or more. Here, the restoration rate and the elongation rate are defined in the above range because when the restoration rate is less than 60%, the liner 7 breaks when receiving an impact force such as when the container falls, This is because there are cracks. For the same reason, the elongation is set to 100% or more. The elongation is the time when the test piece breaks when a tensile load is applied to the test piece at a rate of 50 mm / min under the condition of 130 ° C. with the test piece of FIG. It is the ratio of the amount of elongation to the original distance of the distance between the chucks (grips).

  The liner 7 is such that such a resin material is melted, supplied to the inner surface side of the top plate portion 1 of the cap shell, and the resin material is embossed into a predetermined shape by a mold. As shown in FIG. 4, the flat plate portion 7a covering the central portion of the inner surface of the top plate portion 1 and the sealing portion for sealing the open end of the mouth portion in the container are integrated with the peripheral portion of the top plate portion 1. It is molded into The sealing portion is formed so as to protrude downward from the inner peripheral edge of the flat portion 7b, and a flat portion 7b that is in close contact with the top of the curled portion 8 that is the open end of the mouth of the container. And an inner rib 7c in close contact with the peripheral surface. Therefore, the inner rib 7c is brought into close contact with the inner peripheral surface of the curled portion 8, and the flat portion 7b is brought into close contact with the outer peripheral surface of the curled portion 8 by drawing forming of a corner portion described later. Has been.

  As described above, since the liner 7 in the present invention is made of a synthetic resin excellent in elongation, it can be effectively brought into close contact with the curled portion 8. There is a possibility that the opening torque may be increased, or a so-called surplus space for elongation is insufficient and a gap is generated. Therefore, in the present invention, the dimensions of each part of the liner 7 before drawing are set as follows in order to make better use of the characteristics of the material. In addition, the dimension of each part shown below was calculated | required based on experiment of this inventor.

  As described above, the liner 7 according to the present invention includes the flat portion 7b and the inner rib 7c, and the thickness L3 of the flat portion 7b is 80% of the outer peripheral radius r of the curled portion 8 (r × 4). / 5) to 150% (r × 3/2). This corresponds to 1 mm to 1.7 mm in the case of a bottle-type can whose inner diameter D0 of the curled portion 8 is 20 mm.

  When the thickness L3 of the flat portion 7b is thinner than 80% (r × 4/5) of the outer peripheral radius r of the curled portion 8 (less than 1 mm), the corner portion which is a boundary portion between the top plate portion 1 and the skirt portion 2 is formed. When the flat portion 7b is stretched by drawing, there is a high possibility that a surplus of the liner 7 is insufficient and a gap C is generated between the liner 7 and the inner surface of the corner portion. FIG. 2 shows the shape after drawing the corner portion, and the gap C is generated between the inner surface of the corner portion generated by the drawing and the liner 7 stretched by the drawing. There is a high possibility that the sealing performance cannot be secured. Further, if the thickness L3 of the flat portion 7b is larger than 150% (r × 3/2) of the outer peripheral radius r of the curled portion 8 (over 1.7 mm), the amount of the resin material for forming the liner 7 is excessive. As a result, the leading end of the flat portion 7b extended by the above-described drawing of the corner portion is below the curled portion 8 as indicated by the broken line A 'in FIG. This will cause the opening torque to increase. For this reason, the thickness L3 of the flat portion 7b is defined within the above range.

  In the present invention, the length of the flat portion 7b before drawing is defined. Specifically, the length L4 at which the tip of the flat portion 7b before the draw molding projects from the outermost peripheral surface of the curled portion 8 is the state in which the cap shell having the above-described configuration is attached to the mouth portion of the container. 0 ≦ L4 ≦ r × 0.65). That is, it is 65% or less of the outer peripheral radius r of the curled portion 8, which is 0.8 mm or less when the bottle-type can described above is targeted.

  If the so-called protruding length L4 of the flat portion 7b from the curled portion 8 before drawing is less than "0", that is, the tip of the flat portion 7b is retreated from the outermost peripheral surface of the curled portion 8 to the inner peripheral side. Then, the length (or width) of the liner 7 that is in close contact with the outer peripheral surface of the curled portion 8 due to the drawing of the corner portion is insufficient, and as a result, the possibility that the sealing performance is deteriorated increases. On the other hand, when the so-called projecting length L4 of the flat portion 7b from the curled portion 8 before drawing exceeds 65% of the outer peripheral radius r of the curled portion 8, the above-described corner portion is drawn by drawing. The leading end of the flat portion 7b flows down to the lower side of the curled portion 8, as indicated by the broken line A 'in FIG. 2, and this increases the plug opening torque. For this reason, the so-called protrusion length L4 from the curled portion 8 of the flat portion 7b before the drawing is defined in the above range.

  On the other hand, the inner rib 7c of the liner 7 in the present invention is configured such that the outer peripheral surface 7co has a tapered shape and the inner peripheral surface 7ci has a cylindrical shape. The outer peripheral surface 7co is a tapered surface formed obliquely downward in FIG. 1 from a position closer to the center side of the mouth portion than a radial position of the center O of the curled portion 8 in the mouth portion. The inclination angle of the outer peripheral surface 7co with respect to the genera angle θ of the surface, that is, the axis parallel to the center axis of the mouth is set to 15 ° to 45 °. The maximum outer diameter D1 of the outer peripheral surface 7co, that is, the diameter D1 of the intersection between the flat portion 7b and the outer peripheral surface 7co is set to 21.5 mm to 22.5 mm when D0 is φ20 mm.

  When the generatrix angle θ is less than 15 °, that is, when the outer peripheral surface 7co is closer to the flat part 7b, the inner side of the curl part 8 is attached when the cap shell is crowned on the mouth of the container. The hooking condition of the rib 7c is deteriorated, and capping failure and sealing failure are likely to occur. Similarly, when the bus angle θ exceeds 45 °, capping failure and sealing failure are likely to occur, and in addition to this, the portion of the flat portion 7b connected to the inner rib 7c (in other words, the basis of the inner rib 7c) When the cap shell is pressed against the curled portion 8 as the corner portion is drawn, the material flow is promoted. As a result, the tip of the flat portion 7b is As shown by the broken line A ′ in FIG. 2, the curled portion 8 flows to the lower side, which causes the opening torque to increase. For this reason, the generatrix angle θ of the inner rib 7c before drawing is defined in the above range.

  For the same reason, the thickness of the base end portion of the inner rib 7c (the boundary portion between the inner rib 7c and the flat portion 7b) (width measured in the radial direction of the mouth portion: hereinafter referred to as the maximum width) L1, The length L2 of the inner rib 7c is set in the following range. That is, the maximum width L1 of the inner rib 7c is set to (r / 2 ≦ L1 ≦ 3 / 2r) with respect to the outer peripheral radius r of the curled portion 8. That is, it is set to be not less than 1/2 times and not more than 3/2 times the outer peripheral radius r of the curled portion 8, which is 0.6 mm to 1.8 mm when the bottle-shaped can described above is targeted. It is a range. The length L2 of the inner rib 7c is set to (r × 0.6 ≦ L2 ≦ r × 1.5) with respect to the outer peripheral radius r of the curled portion 8. That is, it is set to be 0.6 times or more and 1.5 times or less of the outer peripheral radius r of the curled portion 8, which is 0.7 mm to 1.9 mm when the bottle-shaped can described above is targeted. It is a range.

  When the maximum width L1 and length L2 of these inner ribs 7c are below the above range, the curled portion 8 becomes like the A ′ portion indicated by the broken line in FIG. It will flow to the lower side of this and this will cause the opening torque to increase. On the contrary, if the above range is exceeded, the amount of the resin material for forming the liner 7 becomes excessive, which causes an increase in cost.

  Furthermore, in the cap according to the present invention, the corner portion which is the boundary portion between the top plate portion 1 and the skirt portion 2 is drawn and the liner 7 is brought into close contact with the outer peripheral surface of the curled portion 8. In that case, since the liner 7 is compressed and the material flows (elongates), the drawing is performed so that the amount of compression of the flat portion 7b described above falls within the following range. That is, the ratio (T1) between the thickness T1 of the liner 7 on the top side (upper side in FIG. 2) of the curled portion 8 and the thickness L3 of the flat portion 7b before drawing after the corner portion is drawn. / L3), and the thickness T2 of the liner 7 on the outer side (left side in FIG. 2) in the radial direction of the mouth after the drawing of the corner portion and the thickness L3 of the flat portion 7b before the drawing. Each ratio (T2 / L3) is set to 0.1 to 0.4.

  When these ratios (T1 / L3, T2 / L3) are less than 0.1, the liner 7 is in an excessively compressed state, and the liner 7 is highly likely to cause resin cracking during drawing. 7 reduces the shock absorbing force, and the liner 7 strongly tightens the curled portion 8 to increase the opening torque. On the other hand, if each of the above ratios exceeds 0.4, there is a high possibility that the compressive stress of the liner 7 is insufficient and the state in which the container mouth is well sealed cannot be maintained.

  For reference, the retraction amount L5 of the outer peripheral surface 7co of the inner rib 7c, that is, the position of the base end portion of the outer peripheral surface 7co and the distal end of the outer peripheral surface 7co (lower end in FIG. 1) as viewed in the radial direction of the mouth. The dimensional difference L5 between and is preferably (0.4 × r ≦ L5 ≦ 0.7 × r). When the bottle-shaped can described above is the target, the range is 0.5 mm or more and 0.8 mm or less. If it is less than r × 0.4 mm, the above-mentioned capping failure or sealing failure is likely to occur. Conversely, if it exceeds r × 0.7 mm, the inner rib 7c is less likely to be hooked against the curled portion 8 during capping. Sealing failure is likely to occur, the rigidity of the portion of the flat portion 7b that is the basis of the inner rib 7c is insufficient, and the tip portion of the flat portion 7b is like an A ′ portion indicated by a broken line in FIG. The curled portion 8 flows down to the lower side, which causes the opening torque to increase.

Here, the result of the experiment conducted on the material used for the liner in the present invention is shown. Table 1 summarizes the blending ratios and general properties of the materials in the present invention and the comparative examples. “Elastomer A” and “Elastomer B” are hydrogenated styrene / conjugated diene block copolymers. On the other hand, “D type” of hardness in “general properties” is a surface hardness measured using a type D durometer, and a test piece (three specimens having a thickness of 2 mm × 16 mmφ is overlapped to obtain a thickness of 6 mm × 16 mmφ). Is a value obtained when a durometer (manufactured by Teclock Co., Ltd.) is pressed at 49N under the condition of 25 ° C. “A type” is the surface hardness measured using a type A durometer, and is a value when the durometer is pressed against the sample at 9.8 N under the condition of 25 ° C. “MFR” is the melt flow rate when a load of 37.24 N is applied while heating to 230 ° C. Therefore, both of the present invention examples and comparative examples are included in the composition specified in the invention described in Japanese Patent No. 4319594.

(Compression recovery test)
Using the composition according to the present invention and the composition according to the comparative example, a test piece of 4 mm × 16 mmφ was prepared, and this was heated to 130 ° C. which is the same as the temperature at the time of retort sterilization treatment. Compressed to a ratio of 70%, measured the volume after removing the compression load and allowed to stand for 1 hour, and the ratio of the volume restored by removing the load out of the reduced volume after compression, that is, 70% compression restoration The rate was measured. The results are as shown in Table 2. That is, in the present invention example, the 70% compression recovery rate exceeded 60%, but in the comparative example, it was less than 60%.

(Tensile test)
Using the composition according to the above-mentioned present invention and the composition according to the comparative example, a test piece as shown in FIG. 4 was prepared with a thickness of 2 mm, and this was heated to 130 ° C. which is the same as the temperature during the retort sterilization treatment. In this state, when a tensile load was applied at a speed of 50 mm / min with the test piece sandwiched between chucks, the distance between the chucks when the test piece broke was measured, and the elongation was determined based on the measured value.
The results are as shown in Table 3. That is, in the example of the present invention, the elongation was 100% or more, whereas the elongation in the comparative example did not reach 100%.

(Evaluation)
Using the compositions of the present invention and comparative examples (synthetic resins), a liner is formed on the inner surface of the cap shell, and the liner is attached to the mouth of the bottle-shaped can. A cap was attached. The contents of the bottle-shaped can were water, and the amount was 500 ml. After mounting the cap, the test can which was retorted at 130 ° C. for 30 minutes was dropped from a height of 50 cm onto an iron jig with an inclination angle of 10 degrees with the cap facing downward, and the state of the liner was visually observed. As a result of the examination, no cracking or cracking of the liner was observed in the inventive examples. On the other hand, in the comparative example, cracks and cracks were observed in the liner of the 80% bottle-type can. That is, according to the example of the present invention, it is possible to reliably seal the mouth of the container without increasing the opening torque by keeping the size of each part of the liner within the above-mentioned range, and in addition to this, the drop sealing property It was recognized that it was excellent.

  DESCRIPTION OF SYMBOLS 1 ... Top plate part, 2 ... Skirt part, 7 ... Liner, 7b ... Flat part, 7c ... Inner rib, 7co ... Outer surface of (inner rib), 8 ... Curl part.

Claims (1)

The peripheral portion of the inner surface side of the front SL top plate portion of the cap shell example Bei a skirt portion depending from the periphery of the top plate and the top plate portion, a substantially circular longitudinal section the opening end of the mouth portion of the container a flat portion which abuts the top of the mosquito Lumpur portion formed in an inner rib abuts on an inner peripheral surface of the curled portion is subjected to La Ina over which is formed integrally, 該Ra Ina chromatography is performed It said cap shell by capped on the opening, dense deposition is allowed Relais Toruto sterilized and the flat portion and the front Symbol car le part by drawing a boundary position between the front SL top plate portion and the skirt portion Oite to the method of manufacturing a suitable cap,
The liners may, (A) and hydrogenated styrene / conjugated diene block copolymer 30 to 5 0% by weight load does not flow in 21.18N at 230 ° C., and from 35 to 5 0 wt% (B) Liquid paraffin , (C) 5 to 30% by mass of polypropylene resin, and (D) silicone oil (E) 0.1 to 20 parts by mass of fine powder talc having an average particle diameter of 0.1 to 10 μm is contained with respect to 100 parts by mass of the resin composition containing 2 % by mass or more, and the measurement temperature is 25 ° C. 50% compression stress at 196 N / cm ^{2 to} 490 N / cm ² , (50% compression stress at 130 ° C.) / (50% compression stress at 25 ° C.) ≧ 0.3, after 70% compression at 130 ° C. Formed from a composition having a restoration rate of 60% or more and an elongation at 130 ° C. of 100% or more,
In making pre Symbol liner on the inner surface of the top plate portion,
Before SL 80% to 150% of the outer radius of the front Symbol said curl portion of the thickness of the flat portion,
Molding a length of front Kitaira Tan portion protrudes radially outwardly of the opening portion from the outer peripheral surface of the curled portion to 0% to 65% of the outer radius of the front Symbol curled portion,
And a pre-Symbol inner Li Bed, in the flat portion, as well as the shape formed to protrude annularly from the position of the inner circumferential side than the center of the curled portion around the central axis in the opening, the inner rib the outer peripheral surface formed into a tapered surface inclined at an angle range of 15 ° to 45 ° relative to the axis parallel to the central axis of the front Symbol mouth,
And 50% to 150% of the outer radius of the front Symbol curl portion thickness measured in the radial direction of the opening portion at the boundary portion between the flat portion of the front Symbol in ribs,
Molding the protruding length from the flat portion of the front Symbol inner rib 60% to 150% of the outer radius of the front Symbol curled portion,
The drawing is performed so that the compression amount of the flat part is 60% to 90% on the top side of the curl part and on the outer side in the radial direction of the mouth part.
It characterized the this method of manufacturing a cap suitable for retort sterilization.

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