JPS5823210B2 - Method for manufacturing curved tube film casing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a curved tube film casing used for filling ham, sausage, etc.
This is a method for manufacturing a tube film casing curved into a ring shape, which has a particularly large degree of curvature and whose degree of curvature hardly changes even when the contents are filled and heat sterilized.

A casing in which a heat-shrinkable tubular film made of vinylidene chloride resin, polyester resin, etc. is curved into a ring shape is well known. A method of bending the tube by wrapping it around a support whose outer circumference is cylindrical and heat-shrinking the contact surface with the roller has been proposed. It has been proposed to also heat the outer periphery.

In these methods, a straight tubular film is curved, so printing is done on the tube surface before bending (if necessary, printing is done taking into account the distortion of the figure due to the curvature), and a ring casing is manufactured, resulting in beautiful printing. However, there are various problems when manufacturing a tube film casing with a large degree of curvature.

In other words, in order to obtain a tube with a high degree of curvature, it is necessary to use a tube film with a high heat shrinkage rate and to cause only the inner surface to shrink significantly. When the material is contracted to a large extent, distortion is likely to occur at the boundary of the contact portion, and the border between the inner and outer peripheries becomes taut, creating a keloid-like shape, or the boundary line tends to crack.

In addition, if the inner circumferential surface undergoes a large amount of heat shrinkage, there will be a large difference in the heat shrinkage rate between the inner circumferential surface and the outer circumferential surface. During heat sterilization, the outer periphery, which has a high shrinkage rate, contracts significantly, so the warp of the ring casing returns and the degree of curvature decreases.

To avoid this, when heat sterilization is done by tying the ligatures at both ends with a string, or placing them in a retainer and heating them, the outer film shrinks, causing the inner film to sag, causing the inner periphery of the filling to sag. I get a constriction.

Such constrictions not only spoil the appearance of the packaged product, but also
The film at the neck part separates from the contents, and meat juices accumulate in that part, making it more likely to spoil.

The method disclosed in Japanese Patent Publication No. 50-39112 in which both the inner and outer peripheries are heated has the effect of lowering the heat shrinkage rate of the outer periphery film, and the return of the degree of curvature during heat sterilization is reduced. Because the circumference is also heat-shrinked, it is difficult to obtain a ring-shaped tube casing with a large degree of curvature, just as it would be if a film with a small heat shrinkage rate was used, and in order to forcibly increase the degree of curvature, the inner circumference must be heated strongly. Then, as mentioned above, large distortion occurs at the contact boundary line with the heating roller.

The present invention provides a method for manufacturing a ring-shaped tube film casing, which hardly changes the degree of curvature even when the inner and outer circumferences shrink due to heat treatment after filling with contents, and which does not have a boundary line with large distortion between the inner and outer circumferences. be.

The present invention will be explained in detail below. In Figure 1, the diameter of the inflated ring-shaped casing is d1, the radius of curvature of the inner circumference is r1, the length of the arc of the inner circumference of the tube with an arbitrary circumference angle θ radians is L□, the arc of the outer circumference If the length of is L2, then L
1=rθ ・・・・・・・・・・・・・・・
・・・・・・・・・(1) L2=(r+d)θ・
・・・・・・・・・・・・(2), so (1)
From equation (2) and equation (3), when this tube is heated, the inner circumference becomes 81 x 100%.
, the outer circumference shrinks by 82 x 100%, and X = 1-81
．． Assume that Y=1-82, and that the inner circumference and outer circumference of this contracted tube have changed to L1't L12, respectively, and the radius of curvature of the inner circumference has changed to r'.

Furthermore, considering that d does not substantially shrink due to the filled contents, r'<1.1r if the change in the radius of curvature of the ring-shaped casing before and after heating is suppressed to within +10%.
・・・・・・・・・・・・・・・・・・・・・・・・
...... From formulas (6) and (7), X = 1-81. Since Y= 1-82, (8)
In other words, the preferable shrinkage rate of the inner peripheral film is calculated from the ratio of the radius of curvature of the ring-shaped tube casing to the tube diameter, and the shrinkage rate of the outer peripheral film using the formula (9).

Also, in order for the change in the radius of curvature to be smaller than 0, S2≧S
1 ・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・(10) The above calculations were performed assuming that the film shrinks freely, but if the tube is filled with contents, Since the film is prevented from shrinking freely, the shrinkage rate when filling the contents is smaller than the free shrinkage rate, and the shrinkage rate of the casing during normal ring casing filling is 70% of the free shrinkage at the outer periphery. will not exceed.

Furthermore, in the present invention, the shrinkage rate of the inner circumference is specified in order to suppress the increase in the radius of curvature and prevent folds or sag in the inner circumference when the outer circumference shrinks, as described above. If folds or sag occur on the inner circumference, the film in that area naturally shrinks freely.

Therefore, if the shrinkage rates of the inner peripheral film and the outer peripheral film in the free state (85°C hot water) are 5X100% and 5oX100%, S2≦0.7So, so no sagging occurs in the inner peripheral part. Also, if the shrinkage rate of the inner periphery is large and no sagging occurs, the shrinkage of the inner periphery is also prevented by the contents, so 00)
The relationship in the formula is applied as is, So≧S...
・・・・・・・・・・・・・・・・・・・・・・・・
......αO) That is, for example, if the shrinkage rate SoX 100% of the outer peripheral film in the free state is 10% and r/d = 1, that is, 10%≧5X100%>2.6% r/d If = 1.5, S>0.03510
%≧5xlOO%〉3,5% If r/d=2, S>0.04110%≧
S
If % 5oX100% is 6% and r/d=1, the right side becomes -, so 6% ≥ 5
00%≧0% If r/d = 1.5 then S > 0.6%6
%≧5X100%≧0.6% If r/d = 2, S>1.2%6%≧5x
ioo%≧1.2% If r/d=3, S>2.0%6%≧
The shrinkage rate may be in the range of 5×100%≧2.0%.

Furthermore, when a ring-shaped casing is filled with contents and heated, a certain degree of heat shrinkage is necessary to ensure that the contents and film are in close contact with each other and to improve storage stability. 2 as free thermal contraction rate in hot water
% or more, and if the heat shrinkage rate is too high, it will be difficult to adjust the shrinkage rate of the inner and outer peripheries to a preferable range, so the heat shrinkage rate of the similar outer periphery should be 10% or less. is necessary.

Regardless of the manufacturing method, the heat shrinkage rate of the inner circumferential portion is generally smaller than that of the outer circumferential portion, and as shown in equation 00), it needs to be smaller.

A ring-shaped tube film casing having the above-mentioned heat shrinkage rate is produced by sandwiching both ends of a heat-shrinkable tube film between two sets of pinch rolls, and filling the tube between them with fluid to inflate it. , at least a part of the inflated tube is advanced while being wound around a shaping roll having a cylindrical outer circumference, and the tube is uniformly heated from the outside while being wound around a support cylinder, and the tube is advanced on the cylinder. The tube film is obtained by a method of strongly bending the tube film by stretching the outer circumference and simultaneously contracting the inner circumference.

That is, of the two sets of pinch rolls, the take-off side pinch roll after the shaping roll has a conical shape or a truncated conical shape,
By setting the moving speed of the inner circumference of the tube on the shaping roll to be slower than the circumferential speed of the delivery roll and the movement speed of the outer circumference to be faster than the circumferential speed of the delivery roll, the inner circumference of the tube is shrunk and the outer circumference is All you have to do is stretch it out.

According to the manufacturing method of the present invention, since uniform heating is performed, the shrinkage rate of the tube in the circumferential direction gradually and continuously changes from the outer circumference toward the inner circumference, and there is no boundary line in the shrinkage rate. figure,
In addition, by changing the apex angle of the truncated cone of the take-up roll and the speed ratio of the delivery roll and take-up roll, the elongation rate of the outer circumference and the shrinkage rate of the inner circumference can be freely adjusted.
The shrinkage rate ratio of the inner and outer circumferential films can be freely changed.

Next, the method for manufacturing a curved casing of the present invention will be explained in detail with reference to the drawings.

In Fig. 2, 1 is a heat-shrinkable tube film wound into a roll, passed through pinch rolls 2 and 2' on the delivery side, passed around the shaping roll 6 for half a turn, and pinched on the take-up side 4 and 4'. It is wound onto a roll 8 through rolls γ and γ'.

At this time, gas is trapped inside the tube 3 between the pinch rolls 2, 2' and 4, 4', and the tube 3 is expanded.

2 and 2' are ordinary parallel rolls, but 4.4' is the third roll.
As shown in the figure, it is shaped like a truncated cone or a cone and is installed so that the tangent lines of each roll are approximately perpendicular to the center line of the shaping roll, and the inner peripheral part where the liquid directly contacts the shaping roll of the tube film is close to the apex angle of the cone. Now, the outer periphery is 4' and 4', respectively, near the bottom.
It is increased while being sandwiched between the rolls.

The shaping roll 6 may be any guide that causes the gas-filled tube to draw a semicircular or circular trajectory when it rotates around the tube for half a turn or several times, for example, as shown in FIG. 2. Note that it may be a combination of several support rods in a circular shape, or of course it may be one large cylinder or semi-cylinder.

A hot water bath 5 is provided to uniformly heat the tube at the portion in contact with the shaping roll, and the tube is deformed into a shape along the outer periphery of the shaping roll at this portion.

At this time, the peripheral speed of the portion near the bottom of the take-up rolls 4, 4' that sandwich the outer periphery of the tube on the shaping roll is:
2, 2' and 2' so that the peripheral speed of the part near the apex angle of 4, 4' sandwiching the inner peripheral part is faster than the peripheral speed of the delivery roll 2°2' and slower than the peripheral speed of 2, 2'. Since the rolls 4 and 4' are driven, the inner circumference of the tube is contracted and the outer circumference is expanded when the tube runs on the shaping rolls.

Heating when passing over the shaping rolls provides a contraction force to cause shrinkage of the inner circumference, and also facilitates deformation when stretching the outer circumference, but also depends on the temperature and heating time (film The shrinkage rate of the product can be freely controlled by changing the speed (adjusted by the running speed, number of film wraps, etc.).

Depending on the uniform heating temperature and heating time, the shrinkage ratio of the inner and outer peripheries also changes to a certain degree, but 2,2' and 4,4
By changing the speed of ', the ratio of the shrinkage rate between the inner and outer circumferences can be changed, and a preferable shrinkage rate can be maintained.

The uniform heating is preferably carried out at a temperature at or slightly higher than the operating temperature of the curved tube film, and is generally carried out at 85°C to 105°C.

The heating time is 0.1 seconds to several tens of seconds, and is usually 0.1 seconds to several tens of seconds.
5 seconds to 10 seconds is preferred.

Note that for heating, instead of a hot water bath, other liquid baths, heated air, or gas such as steam may be used.

Example 1 A seamless fabric made of a copolymer of vinyl chloride and vinylidene chloride obtained by a conventional inflation method, with a thickness of 0.05 mm.
A ring casing was manufactured from a roll tube film of 90 m and 71 L during m+ folding.

The process conditions at this time are as shown in Figure 2, and the outside diameter of the shaping roll is 8.
A tube of 0 m7IL was used, and the tube was wrapped in hot water at 98° C. about 1/2 of the way around the shaping roll, and the tube was immersed in the hot water up to the center of the shaping roll, and the immersion time was 1.2 seconds.

The tube film tension on the shaping roll was set such that the speed ratio with respect to the take-up conical roll was reduced by 30% on the inner circumferential side and increased by 85% on the outer circumferential side, based on the sending-out film speed.

The shrinkage rate of the roll film used in Mata was 28% at 98° C. in the longitudinal direction of the tube.

The outer circumference of the ring casing manufactured under these conditions is 4 in the longitudinal direction.
The ring-shaped casing had been stretched by 5% and shrunk by 27% on the inner circumference, and had no wrinkles inside or outside, and had a clean appearance.

This ring casing had a diameter of 57 mm when inflated with air, a radius of curvature of 55 mm at the inner periphery, and an internal shrinkage rate of 1.2% and an outer circumferential shrinkage rate of 5% at 85°C in the longitudinal direction of the tube.

After filling this tube with the sausage raw material and ligating both ends of the ring, the product was sterilized by immersing it in water at 85°C for 40 minutes, and the resulting product retained the shape and appearance before filling without forming cracks on the inner circumference of the ring. It was clean with no wrinkles and had sufficient commercial value.

Example 2 A seamless tubular film made of the same vinyl chloride and vinylidene chloride copolymer as in Example 1, with a thickness of 0.05 mm and a folding length of 65 mm, was rolled into a ring casing using the apparatus shown in Fig. 1. Manufactured in

At this time, a shaping roll having a diameter of 125 mm was used, and the tube wound approximately 1/2 times around the shaping roll was immersed in hot water at 95° C. for a dipping time of 1.0 seconds.

The tube film tension on the shaping roll was set such that the speed ratio with respect to the take-up conical roll was reduced by 30% on the inner circumferential side and increased by 85% on the outer circumferential side, based on the sending-out film speed.

The completed ring casing has an outer circumference of 15 mm in the longitudinal direction of the tube.
% elongation and 27% shrinkage on the inner periphery, and the resulting ring casing had a diameter of 41 mm when inflated, a curvature radius of 80 mm on the inner periphery, and shrinkage rates on the inner and outer peripheries were 7.5% and 2.1%, respectively. there were.

In this case as well, the product obtained by filling, sterilizing and cooling in the same manner as in Example 1 was free of wrinkles, retained its shape and appearance before filling, and had sufficient commercial value.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the relationship between the diameter, curvature, and inner and outer circumference lengths when the curved tube casing of the present invention is filled with contents, and Fig. 2 is a process diagram showing an example of the method for manufacturing the curved casing of the present invention. , FIG. 3 is a detailed view of the take-off roll of FIG. 2. 1: Raw tube, 2, 2': Pinch rolls on the sending side, 3: Inflated tube, 4.4': Pinch rolls on the receiving side, 5: Hot water bath, 6 Two shaping rolls, 7.7': Intermediate roll, 8: Product winding roll.

Claims (1)

[Claims] 1. A heat-shrinkable thermoplastic resin film in the form of a tube is sandwiched between two sets of pinch rolls on the delivery side and the take-up side, and the tube between the rolls is filled with gas to inflate it. In this method, at least a part of the inflated part is uniformly heated from the outside, and the tube is moved and bent while being wound around a shaping roll whose outer circumference is approximately circular. By using a truncated conical tube, the moving speed of the inner circumference of the tube on the shaping roll is slower than the circumferential speed of the delivery roll, and the moving speed of the outer circumference of the tube on the shaping roll is faster than the circumferential speed of the delivery roll. The inner periphery is shrunk and the outer periphery is expanded at the same time, and the heat shrinkage rate at 85°C of the outer periphery film of the thus obtained curved tube film casing is 5oX100%, the diameter of the tube is d1, the radius of curvature of the inner periphery of the ring is r 8 of the inner peripheral film when
A method for manufacturing a curved tube film casing, characterized in that the heat shrinkage rate at 5° C. is 5×100% and 5o×100 is in the range of 2 to 10%.