JPS6359869B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a sleeve-forming sheet used for covering and protecting fragile articles such as glass bottles. Conventionally, the outer surface of a glass bottle, etc. is covered with a sleeve made of a heat-shrinkable synthetic resin sheet, and the sleeve is shrunk by heating to cover the outer surface of the glass bottle, etc., so as to protect the glass bottle, etc. is being carried out. Particularly when shrink-coating glass bottles subjected to internal pressure, such as those for carbonated beverages, it is an important safety issue to prevent bottle fragments from scattering in the event of breakage. Therefore, as the above safety standard, JIS-S2306
(Test method for anti-scattering performance of glass bottles for carbonated beverages)
When applying the above-mentioned bottle breakage test using various synthetic resin sheets as the material for the protective sleeve, it was found that the safety at the time of breakage (fragment scattering rate) is correlated with the tensile strength and elongation of the material sheet. It turns out that there is. That is, when the results of the above bottle breakage test were graphed with the tensile strength and elongation (measured in the circumferential direction of the sleeve) of the sleeve forming sheet as both axes,
As shown in FIG. 1, the sleeve-forming sheets that passed the bottle-breaking test were limited to those with tensile strength and elongation within a certain range. If the tensile strength or elongation is less than a certain value, it will be rejected, and if the tensile strength or elongation exceeds a certain value, the fragments will scatter in the axial direction in the form of cannonballs, which is extremely dangerous. I understand. In addition, in the above test, a 300ml carbonated drink bottle (170g/piece) was used as a glass bottle for testing.
Measurements were taken at a bottle temperature of 25°C with an internal pressure of 4.5Kg/cm ² applied.
The measurement method is based on JIS-S2306, and the fall height is 75cm.
It was carried out in In addition, the tensile strength and elongation are 10
A sample of mm x length 40 mm was taken along the circumferential direction of the sleeve, and a tensile test was performed and measured. Among the various synthetic resin sheets currently in use, polyvinyl chloride sheets or stretched polystyrene sheets have been developed as materials for shrinkable sleeves that pass the above test. However, the above-mentioned protective sleeve is required not only to be safe in the event of breakage, but also to be durable against vibrations and impact forces during transportation of glass bottles, etc.
The conventional polyvinyl chloride sheets and the like have a disadvantage in that they are inferior in buffering and protecting properties of glass bottles against these external forces. Therefore, both polyvinyl chloride sheets and stretched polystyrene sheets have problems in terms of covering performance during shrinkage and strength during use, and improvements have been desired. Furthermore, as a heat-shrinkable sheet forming the sleeve, for example, the shrinkable expanded polystyrene sheet disclosed in U.S. Pat. There were problems with the safety and lack of practicality. In addition, the foamed polystyrene sheet has the drawback of poor surface smoothness and poor printability, and the sheet surface is easily scratched.
Furthermore, after shrink-covering the glass bottle with a sleeve, when the glass bottle is continuously transferred on a vibrating conveyor, etc., the glass bottle does not move smoothly because the surface is not smooth, and there is a risk that the glass bottle will stagnate in the middle of the travel path. The present invention provides a sleeve-forming sheet that is excellent in both shock-absorbing properties during wheel transport and safety in the event of breakage, and also has good shrinkage coverage, etc., and also provides an efficient sleeve-forming sheet. The purpose is to propose a manufacturing method for In the present invention, a shrinkable foamed polystyrene sheet and a shrinkable non-foamed polystyrene film are laminated, and the foamed sheet has a higher shrinkage rate than the non-foamed film, and its skin layer is larger than the laminated surface with the non-foamed film. The non-laminated side is thicker, the non-foamed film contains 1 to 30% by weight of rubber, and the residual gas amount of the foamed sheet is 0.3mol/
Kg or less, and the shrinkage percentage in the machine direction of the laminated sheets is 60% or less, the shrinkage percentage in the width direction is 10% or less, and the shrinkage percentage in the machine direction is greater than the shrinkage percentage in the width direction, and the shrinkage percentage in the machine direction is less than 10%. Tensile strength is 1.5~7Kg,
The gist is a sleeve-forming sheet that has an elongation rate of 13% or more and is characterized by having a foamed sheet as the inner surface and joining both ends in the machine direction. Next, embodiments of the present invention will be illustrated below with reference to the drawings. As shown in Fig. 2, the sleeve forming sheet S
1 is a laminate of a shrinkable foamed polystyrene sheet 1 and a shrinkable non-foamed polystyrene film 2, and both 1 and 2 have so-called heat shrinkability, meaning that they shrink when heated. The shrinkability is added by stretching during extrusion molding, and the magnitude of the shrinkage force or shrinkage rate varies depending on the molding conditions such as the amount of stretching or the composition of the resin material. In the case of the foamed sheet 1, resin skin layers are formed on both sides by extrusion foaming, and the thickness thereof varies depending on the degree of cooling during molding. Therefore, the sleeve-forming sheet S of the present invention can be formed by appropriately setting the above-mentioned molding conditions or the composition of the raw material. First, the polystyrene resin that is the material of the foamed sheet 1 is a styrene polymer obtained by polymerizing vinyl aromatic monomers such as styrene, vinyltoluene, isopropylstyrene, α-methylstyrene, nuclear methylstyrene, chlorostyrene, and tertiary-butylstyrene. Combined with styrene monomer,
1.3-Butadiene, butyl acrylate, ethyl acrylate, alkyl acrylates such as 2-ethylhexyl acrylate, alkyl methacrylates such as methyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, acrylonitrile,
Obtained by copolymerization with vinyl acetate, α-methylethylene, divinylbenzene, dimethyl maleate, and diethyl maleate. A styrene copolymer containing 50% by weight or more of styrene monomer is used, and the resin includes aliphatic hydrocarbons such as propane, butane, isobutane, pentane, neopentane, isopentane, hexane, butadiene, cyclobutane, cyclopentane, and cyclohexane. Add blowing agents such as cycloaliphatic hydrocarbons such as methyl chloride, methylene chloride, dichlorofluoromethane, chlorotrifluoromethane, dichlorodifluoromethane, dichlorodifluoromethane, trichlorofluoromethane and other halogenated hydrocarbons and heat. Foam sheet 1
form. The thickness of the foamed sheet 1 can be in the range of 0.1 to 1 mm, but a thickness of 1 mm or more is not preferred because it is difficult to wind the sheet into a roll and cannot be shipped in a roll. As the non-foamed film 2, the above foamed sheet 1
The same styrene-based resin as the material can be used, and the non-foamed film 2 contains 1 to 30% by weight of rubber such as butadiene and butene. By containing the rubber component, it becomes possible to freely control the stretching of the non-foamed film 2 when the non-foamed film 2 and the foamed sheet 1 are simultaneously extruded and laminated using a co-extruder. In the present invention, it is necessary to provide a stretching difference between the non-foamed film 2 and the foamed sheet 1, and if the shrinkage rates of the non-foamed film 2 and the foamed sheet 1 are the same, it is necessary to use this laminated sheet to form a sleeve. When the non-foamed film 2 is formed and shrink-covered on a bottle body, cracks occur in the non-foamed film 2. In order to prevent this, it is necessary to make the shrinkage rate of the non-foamed film 2 smaller than that of the foamed sheet 1, and for this purpose, a rubber component that can control the stretching of the non-foamed film 2 is added during extrusion. is needed. However, the rubber content should be in the range of 1 to 30% by weight, preferably 2 to 10% by weight, because if it exceeds 30% by weight, it will be easily attacked by the solvent of the printing ink when printing on the film 2. Undesirable. In addition, when pigments such as titanium white are included, the light transmittance is reduced and the reflectance is increased, so when laminated with the foam sheet 1, the color development during printing is good and it also has the effect of improving the surface luster or gloss. The content is preferably 5% by weight or less. The thickness of the non-foamed film 2 is in the range of 2 to 160 .mu.m. If it is less than 2 .mu.m, the strength will be weak and scratches will easily occur during printing, and if it is more than 160 .mu.m, the winding property will be poor, which is not preferable. Furthermore, when printing is performed on a shrinkable sheet in which the above foamed sheet 1 and non-foamed film 2 are laminated, the surface of the non-foamed film to be printed is partially corroded by the solvent of the printing ink. When this shrinkable sheet is used to form a sleeve and shrink-cover a bottle or the like, fine cracks will occur on the printed surface over time or due to changes in outside temperature. In the present invention, the disadvantage of poor solvent resistance to the printing ink container, which causes cracks, can be improved by containing polyethylene wax in the non-foamed film 2. The composition of non-foamed film 2 is 0.03 parts of polyethylene wax per 100 parts of styrene resin.
-6.0 parts can be used,
If it is less than 0.03 part, there will be little effect such as improving solvent resistance.
If it exceeds 0.6 parts, the surface of the film deteriorates and printability deteriorates, so both are undesirable.
Among the above content ranges, it is most effective to implement the content within the range of 0.03 to 4.0 parts. The polyethylene wax used in the present invention is an ethylene low polymer produced by polymerization of ethylene or thermal decomposition of polyethylene, and its molecular weight can be in the range of 500 to 15,000, particularly in the range of 1,000 to 1,000. ~10000 is preferred. In other words, the drop point (ASTM, D566 ²
If the molecular weight is less than 1000, the drop point will be low and the screw bite will be reduced during extrusion molding, and a small amount of polyethylene wax cannot be mixed into the styrene resin, which is not preferable. On the other hand, if the molecular weight exceeds 10,000, the drop point will become high and the miscibility with styrene resin will deteriorate, which is not preferable. When the above-mentioned molecular weight range is expressed as a drop point value, a molecular weight range of approximately 50 to 150°C can be used, preferably a range of 90 to 150°C. Next, when printing is applied to the sleeve-forming sheet of the present invention, there is no problem when printing in a single color, but when printing in multiple colors, the sheet passes through printing rolls equal to the number of colors. At this time, when the sleeve-forming sheet passes through the printing rolls, it is pressed and compressed in the thickness direction, and as a result, it stretches in the plane direction. The problem was that the size of the image changed and color shift occurred. For example, when printing with four colors on a 930 mm wide sleeve forming sheet with a thickness of 0.35 mm (including 15 microns of non-foamed film), the width increases by 1.4 mm in the first printing, and further increases by 0.4 mm in the second printing. It has been measured that the paper stretches by about 2.0 mm after four-color printing is completed. In order to prevent such color misregistration, it is possible to slightly vary the plate size for each color to accommodate the elongation of the sleeve forming sheet, but each time the quality of the sleeve forming sheet changes, it is possible to pass it through the printing roll in advance. It was necessary to measure the elongation due to the elongation and make a plate with dimensions that matched the elongation, which was extremely troublesome and caused an increase in costs. Therefore, by compressing the sleeve-forming sheet of the present invention in advance, the above-mentioned color shift problem can be solved, and a sleeve-forming sheet that can be used for multicolor printing without any problem can be manufactured. That is, if the sleeve-forming sheet of the present invention is passed between a pair of compression rolls with a predetermined gap, and the laminated sheet is compressed by 3 to 30% in the thickness direction, it will at the same time be slightly elongated in the plane direction. The gap between the above compression rolls should be 93% to 50% of the original fabric thickness, and if the laminated sheet is compressed by 5% to 35% in the thickness direction immediately after passing through the compression rolls, the restoring force of the laminated sheet will Practically 3 to 30 in the thickness direction
% compressed sleeve forming sheet S for printing is obtained. The above range is suitable for the amount of compression; compression of 3% or less will not sufficiently prevent elongation during printing;
% or more is undesirable because a misalignment occurs between the surface and the inside of the compressed sheet, resulting in wrinkles on the surface. Note that the compression roll can be used at room temperature, but a heating roll may be used so that heating can be performed simultaneously with compression. An example of a compression roll is the roll diameter.
It is possible to use a pair of 300φ heating roll and a compression roll with a roll diameter of 100φ, or a pair of rolls with a diameter of 200φ, but if the roll diameter is too small, the laminated sheet will not move along the roll. It is unsuitable because it wrinkles and may cause cracks when shrink coated on bottles. As described above, if printing is performed using the sleeve forming sheet S that has been compressed in advance, this sheet S
is already sufficiently compressed, so that when it passes through the printing rolls it is hardly compressed anymore and no elongation in the plane direction occurs. Therefore, by using the pre-compressed sleeve-forming sheet of the present invention, there is no need to adjust the dimensions of the printing plate to prevent color misalignment during multi-color printing, as is the case in the past, and the size of the printing plate is the same for each color. You can use the plate size. In addition, in the present invention, in order to further improve safety when the bottle breaks, the foamed sheet 1 forming the sleeve forming sheet S contains rubber such as butadiene and butene similar to that used for the non-foamed film 2. can be contained. The amount of rubber to be included is
25% by weight or less based on foam sheet 1, preferably
It is 0.5 to 25% by weight, more preferably 0.5 to 15% by weight. By incorporating this rubber component into the foamed sheet 1, the physical properties of the sleeve-forming sheet S, etc., such as tensile strength and elongation values, which will be described later, are adjusted to improve safety in the event of breakage. In addition, the rubber content is 25
If it exceeds % by weight, it becomes difficult to impart sufficient shrinkability even by stretching treatment, and the shrinkable covering effect as a sleeve cannot be exerted, making it unsuitable. Further, one or both of the foamed sheet 1 and non-foamed film 2 forming the sleeve-forming sheet S of the present invention contains 0.01 to 3% by weight of a plasticizer having a solubility parameter (SP value) in the range of 8 to 11.0. can be done. The above-mentioned solubility parameter (SP value) is a value indicating the ease with which a resin and a solvent, etc. dissolve in each other. (SP value) is approximately 9.1, so as a plasticizer to be included in it,
It is preferable that the SP value is in the range of 8 to 11.0. Examples of such plasticizers include diethyl phthalate (SP value 9.9 to 10.0; numbers in parentheses below indicate SP value), dibutyl phthalate (9.4), di2-ethylhexyl phthalate (9.0), and dimethyl phthalate (10.5 to 10.5). 10.7), dipropyl phthalate (9.75), diisooctyl phthalate (9.6), butylbenzyl phthalate (9.8), di-n-hexyl phthalate (9.1), dianiphanyl phthalate (9.0), dibutoxyethyl phthalate (8.0), etc. phthalate esters, aliphatic esters such as dioctyl adipate (8.6), dibutyl sepacate (9.2), dioctyl sepacate (8.7), butyl oleate (9.0), dianiphanyl sebacate (8.3), and Phosphate esters such as tricresyl phosphate (9.7) and triphenyl phosphate (10.5),
Furthermore, various substances such as ethyl phthalyl ethyl glycolate (10.2) and butylphthalyl butyl glycolate (9.65) can be used. If the plasticizer content exceeds 3% by weight, it will be difficult to adjust the viscosity of the resin when producing a sheet using an extruder, and the resulting sleeve-forming sheet will be stretched unevenly, so it is not preferable. , 0.01% by weight
Below this, the lamination adhesiveness between the foamed sheet 1 and the non-foamed film 2 cannot be exhibited. By containing a plasticizer, when shrink-covering a glass bottle with the sleeve-forming sheet of the present invention, or during use of a glass bottle coated with a sleeve, especially when washing with pressurized water jet, etc. This is effective in preventing peeling between the foamed sheet 1 and the non-foamed film 2. Next, in the present invention, in order to improve safety when the bottle is broken, the tensile strength and elongation of the sleeve forming sheet S are measured (Measurement method: 10 mm width cut out along the flow direction of the sleeve forming sheet ×
The test is performed using a Tensilon tester using a dumbbell test piece with a length of 40 mm. ), use a material with a tensile strength of 1.5 to 7 kg and an elongation rate of 13% or more. To explain in detail the relationship between the above tensile strength and elongation values and the bottle breakage test, first, when a bottle falls and breaks, the protective sleeve expands rapidly and the sheet forming the sleeve breaks. The impact force at this time is absorbed by the tensile strength of the sheet, and then the impact force is gradually absorbed by the elongation of the sheet, reducing the force of scattering the bottle fragments and reducing the distance the fragments are scattered. Therefore, the values of tensile strength and elongation have a great influence on the results of the bottle breakage test, and the range of tensile strength and the elongation are important. In addition, in order to further improve the safety when the bottle is broken, polystyrene resin, polyethylene, or ethylene-vinyl acetate copolymer is added between the non-foamed film 2 and the foamed sheet 1 that form the sleeve-forming sheet of the present invention. It is possible to provide a non-foamed film layer 20 made of a polyolefin resin such as (see FIG. 6). This film layer 20 may contain 1% by weight or more of rubber, or if the film layer 20 is made of polystyrene resin, it may contain 10% by weight or more of rubber.
The polyolefin resin may be contained in an amount of % by weight or more. Foamed sheet 1 and non-foamed film 2 as described above
The sleeve-forming sheet S is manufactured by laminating the sleeves and the sleeves at the same time as they are molded by co-extrusion, and an example of the manufacturing apparatus is shown in FIG. 3 is an extruder for the foamed sheet 1, 4 is an extruder for the non-foamed film 2, and the molten resin extruded from both is delivered to the central foamed sheet 1 at the confluence section 5.
The unfoamed resin is surrounded by the resin that will become the non-foamed film 2, and the unfoamed film 2 is joined to the die head 6, which has an annular gap for inflation molding. In addition, at the above confluence point, the foam sheet 1
The temperatures of both resins are set so that the viscosities of the resin that will become the non-foamed film 2 and the resin that will become the non-foamed film 2 match. By adjusting the flow of both resins and keeping the ratio of extruded resin amounts constant, the thickness ratio of foamed sheet 1 and non-foamed film 2 is controlled to a predetermined value when forming a laminated sheet. It is necessary to do this. The combined resins are extruded from the die head 6 in a double layered cylindrical shape, and are stretched into a double bag shape with the foamed sheet 1 on the inner surface and the non-foamed film 2 on the outer surface, and are passed through the air injection tube 7, etc. Cooling air is blown from the foam sheet 1 side on the inner surface to cool the sheet. Both resins cooled by air blowing solidify and form a laminated sheet in which the foamed sheet 1 and the non-foamed film 2 are laminated. Then, a predetermined stretching process is applied to produce a shrinkable sleeve-forming sheet S. Regarding the cooling air, air injection pipes 7 are provided on both the inner and outer surfaces so that cooling can be performed from both sides, and the amount of cooling air is set to be larger on the inner foamed sheet 1 side than on the outer non-foamed film 2 side.
The same effect can be obtained even if the degree of cooling on the foamed sheet 1 side is made larger than on the non-foamed film 2 side. Furthermore, the amount of stretching of the laminated sheet is controlled by the blow-up ratio determined by the ratio of the diameter of the die head 6 and the outer diameter of the plug 8, and the sheet take-up speed. The shrinkage rate of is also determined. The above blow-up ratio is preferably in the range of 1.5 to 3.0, and if it is less than 1.5, when the manufactured laminated sheet is heat-shrinked, it will not shrink in the width direction but will expand, which is preferable as a sleeve-forming sheet S. If it is 3 or more, it is not preferable because it shrinks too much in the width direction, causing problems in coating glass bottles and the like. The sleeve-forming sheet S manufactured as described above is stretched with a higher degree of cooling from the foam sheet 1 side than from the non-foam sheet 2 side, so the foam sheet 1, which has a high degree of cooling, has a small degree of cooling. In addition, it exhibits a higher shrinkage rate than the non-foamed film 2 containing a rubber component, and the foamed sheet 1 itself can be directly blown with air to form the non-foamed film 2.
A thicker skin layer is formed on the surface 11 where the non-foamed film 2 is not laminated than on the surface 10 where the non-foamed film 2 is laminated, and the shrinkage rate is also increased. In addition, by appropriately setting the take-up speed and blow-up ratio during stretching and controlling the amount of stretching in the machine direction and width direction, the shrinkage rate in the machine direction of the laminated sheets can be reduced to 60% or less, and the shrinkage rate in the width direction is 60% or less. 10
% or less, and the shrinkage rate in the machine direction should be greater than the shrinkage rate in the width direction. In the sleeve-forming sheet S formed as described above, the amount of residual gas due to the foaming agent contained in the foamed sheet 1 is kept at 0.3 mol/Kg or less at the time of use, that is, at the time of heat shrinkage of the sleeve, which will be described later. This is to prevent the printed surface of the non-foamed film 2 from peeling off or cracking, since if there is a large amount of residual gas when the sleeve contracts, the thickness of the sleeve will increase due to expansion due to heating.
The residual gas will gradually diffuse over time after extrusion molding, but it may be adjusted by heating and pressing with a hot roll or the like to actively diffuse the gas. In addition, the amount of residual gas can be determined by adjusting the amount of foaming agent added to the foamed sheet 1 in advance, or
It can also be adjusted by using an organic blowing agent as the blowing agent. The sleeve-forming sheet S in which the foamed sheet 1 and the non-foamed film 2 are laminated as described above is
After compressing with a compression roll or printing on the non-foamed film 2 side, it is cut into an appropriate size to form a cylindrical sleeve. At this time, the foamed sheet 1 side of the sleeve-forming sheet S is placed on the inner surface, and the sheet is wound into a cylindrical shape so that the flow direction of the sheet is in the circumferential direction of the sleeve, and both ends in the flow direction are bonded by thermal bonding or the like. They are joined together to form a sleeve A (see FIG. 4). This sleeve A is placed over a glass bottle G, etc., and then heated to shrink the sleeve A and tightly cover the glass bottle G.
(See Figure 5). The size of the sleeve A before heat shrinking is determined by the adhesion when the sleeve A is shrunk and is formed so that there is a gap of about 1 mm between the glass bottle G and the sleeve A when it is placed over the glass bottle G. , also preferred in terms of appearance.
In addition, the sleeve A shrinks in the circumferential direction and becomes thicker in the thickness direction at the same time, but if this change in thickness becomes extreme, the printing surface may bulge due to the difference in the degree of shrinkage between the foamed sheet 1 and the non-foamed film 2. There is a risk of cracks forming on the surface. Therefore, the glass bottle
Adjust the size of sleeve A relative to the actual size. In addition to the glass bottle G, the sleeve A can be used for various purposes such as protecting fragile articles such as various glass products and ceramics. According to the sleeve-forming sheet S of the present invention constructed as described above, the shrinkable foamed polystyrene sheet 1 and the shrinkable non-foamed polystyrene film 2 are laminated, so that the glass bottle G can be shrink-covered as a sleeve. The foam sheet 1, which becomes the inner surface when
It is possible to reliably protect the glass bottle G from vibrations and shocks during transportation, storage, etc. In addition, the non-foamed film 2 on the front side has a smooth surface and very good printability, and it is stronger and less prone to scratches than the foamed sheet 1 alone, so the protection against the glass bottle G is even better. Become something. Therefore, even if the thickness of the glass bottle G itself is reduced, it can withstand use sufficiently, and it is possible to reduce the weight to about 1/2 of the conventional size. Moreover, since the surface has good slipperiness, the glass bottle G can be smoothly transferred by a vibrating conveyor or chute, making it easy to handle. Furthermore, the cushioning properties of the sleeve A are effective in preventing noise caused by collisions between bottles during the bottling process. Next, the shrinkage rate of the foamed sheet 1 on the inner surface side of the sleeve is greater than the shrinkage percentage of the non-foamed film 2 on the outer surface side, and the foamed sheet 1 itself also has a non-laminated surface 11 which is larger than the laminated surface 10 with the non-foamed film 2. has a thick skin layer and a good shrinkage rate, so when the glass bottle G is shrink-coated, the inner surface, which requires a larger amount of shrinkage, shrinks well and can be brought into close contact with the glass bottle G, making it possible to perform shrink-coating very favorably. Ru. By containing 1 to 30% by weight of rubber in the non-foamed film 2, the shrinkage rate of the non-foamed film 2 can be freely adjusted, and the laminated sleeve-forming sheets S can be subjected to a compression process. In some cases, the non-foamed film 2 is sufficiently stretched to obtain a good finish, and also has the effect of improving the tensile strength of the sleeve-forming sheet S as a whole. And the sleeve forming sheet S as a whole is as follows:
The shrinkage rate in the machine direction is greater than the shrinkage rate in the width direction,
By winding the sleeve A so that the circumferential direction is in the above-mentioned flow direction, the sleeve A contracts mainly only in the circumferential direction of the glass bottle G during shrink coating, and hardly contracts in the axial direction. , a predetermined range in the axial direction of the glass bottle G can be sufficiently covered and protected. In addition, by adjusting the tensile strength and elongation values within a certain range, when used as a coating on pressure bottles, it can pass the drop bottle breakage test and has excellent safety with less scattering of bottle fragments when broken. It is possible to exhibit various excellent effects, such as being able to provide a sleeve with a long sleeve. Example 1 (1) Extruder Two single-stage extruders (screw diameter 90 mm) were connected to perform inflation molding by simultaneous extrusion using a circular plug method. Die diameter
75φ (slit width 0.4mm), plug diameter 145φ (therefore the blow-up ratio is 1.93) (2) Raw material composition (a) Compounded polystyrene of non-foamed film 75 parts styrene-butadiene copolymer (butadiene 6
% content) 25 parts Titanium white 5 parts (b) Polystyrene compounded for foam sheet 100 parts Butane 0.345 mol per 1 kg of polystyrene (3) Manufacturing process Melt and knead the resin in (a) above in extruder 4, and transfer to extruder 3. The resin of (b) above is melt-kneaded and sent to the confluence point 5 with the resin (a) coated around the resin (b). Adjust the resin temperature at the confluence point to 181°C in (a) and 170°C in (b). The laminated resins (a) and (b) are extruded from a confluence point 5 into a cylindrical shape through a die 6, stretched while cooling, passed over a plug 8, and taken off at a speed of 16 m/min. The cooling air pressure at this time is 1500Aq on the foam sheet side and 150mmAq or 1800mmAq on the non-foamed film side.0 After passing through the plug 8, cut the sheet into two pieces.
Furthermore, after that, a heat roll (diameter 100mm) with a surface temperature of 92℃
φ) to obtain a sleeve-forming sheet S. (4) Sleeve forming sheet Thickness 0.35mm (including 15μ non-foamed film) Residual amount of foaming agent 0.22mol/Kg Shrinkage rate (heated in oven at 130℃ for 12 seconds) 45% in machine direction, 2% in width direction Light transmittance
40% or less (Visible light wavelength: 380 to 770 mμ) When printing was performed on the above-mentioned sleeve-forming sheet S using a printing ink for ordinary foamed polystyrene sheets, a very good printed surface was obtained. Next, both ends of the sleeve-forming sheet S in the flow direction are joined to form a sleeve A, a glass bottle for coating is preheated at 68°C, and the sleeve A is placed over the glass bottle G, followed by an oven temperature of 160°C.
When the sleeve A was shrink-covered by heating at ℃ for 10 seconds, it was confirmed that the glass bottle G could be protected in a good covering state, and that it had a beautiful finish and the surface had good slippage. Example 2 The sleeve forming sheet obtained in Example 1 was
It is passed between a pair of compression rolls. Roll diameter is 200mmφ each, roll spacing 0.2mm, roll temperature 87
It is ℃. After passing through the compression roll, the thickness of the sleeve-forming sheet S was 0.26 mm (compression rate
25.7%). The foaming ratio of the sheet thus obtained was 6.
times, the remaining amount of blowing agent is 0.22mol/Kg, the compressibility (130
℃ oven for 12 seconds) 45% in the machine direction and 2% in the width direction. Also, as a light transmittance, the wavelength within visible light is 380 to 770.
It was less than 40% between mμ. When multicolor printing was performed on the printing sleeve forming sheet S, it exhibited good printability without stretching in the width direction and without color misregistration. Furthermore, the tensile strength of the above sheet was measured along with conventional products, and the following table was obtained.

【table】

[Table] From the table above, it can be seen that in addition to the effect of preventing printing misalignment due to compression and the effect of preventing warping and cracking during compression due to the inclusion of rubber, it is also excellent in terms of tensile strength. Example 3 In Example 1, the raw material composition (a) non-foamed film was as follows: 100 parts polystyrene, styrene-butadiene copolymer (6% butadiene)
Contains) 16.7 parts Titanium White Instead of 6 parts, this has a molecular weight of 2000 and a drop point.
Sheets for forming sleeves were obtained in the same manner as in Example 1, except that various amounts of polyethylene wax (PE WAX) at 118° C. were added, except for the above changes. This sheet was then printed using a printing ink with a composition of 40% alcohol, 12% toluene, 6% ethyl acetate, 20% pigment, 15% acrylic resin, and 7% cellulose resin. A test was conducted to determine whether or not cracks would occur due to solvents such as ethyl acetate.The results are shown in the table below.

【table】

【table】

[Table] In Experimental Examples 9 and 10, the styrene-butadiene copolymer was excluded from the formulation of the non-foamed film. The test method was as follows. 〇Tensile elongation Tensilon test: Sample shape dumbbell (width 10
mm, length 40mm) Room temperature, tensile speed 1mm/min 〇Solvent resistance Drop one drop of solvent (toluene:alcohol = 1:1) on the film surface with a syringe and measure the time until a hole forms〇Appearance of the film surface Visually determine flatness 〇 Print finish Visually determine ink coverage and unevenness during printing 〇 Crack test After shrink coating a bottle, measure the time until cracks appear on the surface under various temperature conditions (>30 days indicates that no cracks were observed even after 30 days or more.) From the above experimental example, the amount of polyethylene wax was determined by
It is clear that by including the non-foamed film in the range of 0.03 to 6.0 parts, cracks do not occur in the sleeve after printing. Example 4 In Example 1, the raw material composition (a) non-foamed film was as follows: polystyrene 70 parts styrene-butadiene copolymer (butadiene 6%)
A sleeve-forming sheet was produced in the same manner as in Example 1 except that the content was changed to 30 parts titanium white and 5 parts, and 0.05 to 4 parts of the plasticizer of the present invention was added thereto. In addition, only test product 12 contained a plasticizer in the foam sheet. The table below shows the results of various tests performed on each test product along with comparative examples.

【table】

[Table] Among the physical properties, peel strength was determined by tearing a test piece 20 mm wide x 100 mm long at a tearing speed of 100 mm/min, and measuring its load resistance. The rate of peeling was measured by spraying water at a pressure of 3 kg/cm ² onto the test piece from a nozzle with a diameter of 5 mm and observing the peeling state. In the table, the types of plasticizers are DOA: dioctyl adipate DOP: di-2-ethylhexyl phthalate. As shown in the table above, one or both of the foamed sheet 1 and the non-foamed film 2 contain a plasticizer with a solubility parameter (SP value) in the range of 8 to 11.0.
By containing 3% by weight, foam sheet 1
It can be seen that the lamination adhesion between the film and the non-foamed film 2 is very excellent. Example 5 In Example 1, the butadiene content was changed from 3 to 25% by weight during the blending of raw material composition (a) non-foamed film.
(b) 0 to 25% by weight of butadiene in the foam sheet formulation
It is included. For the rest, Example 1
A sleeve-forming sheet was manufactured in the same manner as described above. After printing this sheet on the non-foamed film 2 side, cut it into an appropriate size so that the foamed sheet 1 side is the inner surface and the flow direction of the sheet is in the circumferential direction of the sleeve. It is wound into a cylindrical shape, and both ends in the flow direction are joined by thermal bonding.
Form a cylindrical sleeve. This sleeve was shrink coated onto a glass bottle filled with carbonated beverage. Then, a glass bottle covered with a sleeve was subjected to a bottle breakage test (based on JIS-S2306) to verify safety, and the results are shown in the table below. The test condition is 300ml.
An internal pressure of 4.0 to 4.2 Kg/cm ² was applied to a glass bottle for carbonated beverages, and a mass percentage (%) of 95% or more of the scattered fragments that did not exceed a frame with a radius of 100 cm was considered to have passed.

[Table] As shown in the table above, if the non-foamed film 2 contains butadiene as a rubber component, it will not pass the bottle breakage test, but if the foamed sheet 1 also contains butadiene, it will pass the bottle breakage test. It is clear that you will pass.

[Brief explanation of drawings]

FIG. 1 is a graph showing the suitability of various sleeve materials, FIG. 2 is a cross-sectional view of a sheet according to the present invention, FIG. 3 is a cross-sectional view showing an example of manufacturing equipment, and FIG.
The figure is a perspective view of the sleeve, FIG. 5 is a sectional view of the sleeve in use, and FIG. 6 is a sectional view of a modified example. 1...Shrinkable polystyrene foam sheet, 2...
Shrinkable non-expanded polystyrene film, 3, 4...
Extruder, 6...Die head, 7...Cooling air injection pipe, 8...Plug, S...Sleeve forming sheet, A...Sleeve, G...Glass bottle.

Claims (1)

[Claims] 1. A shrinkable foamed polystyrene sheet and a shrinkable non-foamed polystyrene film are laminated, the foamed sheet has a higher shrinkage rate than the non-foamed film, and its skin layer is the same as the non-foamed film. The non-laminated side is thicker than the laminated side, the non-foamed film contains 1 to 30% by weight of rubber, and the residual gas amount of the foamed sheet is 0.3 mol/Kg or less,
Furthermore, the shrinkage rate of the laminated sheets in the machine direction is 60
% or less, the shrinkage rate in the width direction is 10% or less, and the shrinkage rate in the machine direction is greater than the shrinkage rate in the width direction, and the tensile strength in the machine direction is 1.5 to 7 kg, and the elongation rate is 13
% or more, and is characterized in that both ends in the flow direction are joined with a foam sheet as the inner surface. 2. The sheet for forming a sleeve according to claim 1, wherein one or both of the non-foamed film and the foamed sheet contains 0.01 to 3% by weight of a plasticizer having a solubility parameter of 8 to 11.0. 3. The sheet for forming a sleeve according to claim 1, wherein the non-foamed film contains 0.03 to 6.0 parts of polyethylene wax per 100 parts of styrene resin. 4. The sheet for forming a sleeve according to claim 1, wherein the non-foamed film contains 5% by weight or less of white titanium. 5. The sheet for forming a sleeve according to claim 1, which is made of a laminated sheet compressed by 3 to 30% in the thickness direction. 6. The sleeve-forming sheet according to claim 1, wherein the foamed sheet contains 0.5 to 25% by weight of rubber. 7. The sleeve-forming sheet according to claim 1, wherein the non-foamed film contains 10% by weight or more of a polyolefin resin.