JP3701299B2 - container - Google Patents

Description

  The present invention relates to a container formed by thermoforming using a styrenic resin laminated foam sheet for thermoforming suitable for forming a thermoformed article, and more specifically, when a container is continuously thermoformed, it is generated during heating. The present invention relates to a container excellent in strength and appearance, in which easy sheet sag is effectively prevented, and as a result, occurrence of poor thermoforming is prevented.

  Conventionally, styrene resin foam sheets have been widely used for thermoforming containers and the like, but molded products formed from styrene resin foam sheets have a problem in impact resistance and are easily damaged. For the purpose of improving the impact resistance of a molded product obtained from such a styrene resin foam sheet, a high impact polystyrene resin (hereinafter referred to as HIPS) is applied to a styrene resin foam sheet (hereinafter sometimes abbreviated as PSP). In some cases, abbreviated.) A laminated foam sheet in which sheets are laminated is used as a thermoforming sheet. Further, since the HIPS sheet has a whitened appearance as compared with a PSP made of general grade polystyrene resin (GPPS), laminating the HIPS sheet on the PSP also has an effect of improving the appearance of the PSP. .

  The laminated foam sheet as described above is conventionally manufactured by a method of extrusion laminating HIPS on a pre-manufactured PSP, and is thermoformed using such a conventional styrene resin laminated foam sheet for thermoforming. The container had the following problems during the thermoforming.

  That is, when a container or the like is continuously formed using the above laminated foam sheet, both side edges of the long laminated foam sheet are clamped and conveyed to a heating zone, and both sides of the sheet are heated by a heater in the heating zone. After softening to a moldable state, the process of transferring to a molding zone and molding into a predetermined shape is continuously performed. However, in the case of a conventional styrene-based resin laminated foam sheet, when it is heated in a heating zone, it is likely to sag due to expansion and its own weight (this sag phenomenon is called drawdown). In particular, the container to be obtained is a relatively deep-drawn molded product such as a bowl shape (the ratio between the diameter of the circle having the same area as the area inside the opening of the molded product and the depth of the molded product is 0.25 or more) In particular, in the case of a molded product of 0.4 or more, usually the secondary thickness of the PSP in the laminated sheet (secondary foaming occurs in the PSP when the laminated sheet is heated in the heating zone, and the thickness of the PSP is It is said that the thickness during heating is referred to as secondary thickness) is 1.5 times or more, preferably 2.0 times or more the thickness of the PSP before heating. However, in order to increase the thickness of the PSP, it is necessary to sufficiently heat the laminated sheet by increasing the heating time. However, if the heating time is increased, there is a problem that the drawdown increases.

  Heating heaters in the heating zone are usually arranged above and below the sheet so that the sheet can be heated uniformly from the upper and lower surfaces, but when a large drawdown occurs in the laminated foam sheet, The distance to the heater changes, and the lower surface side of the sheet is close to the heater, so it is overheated, and the upper surface side of the sheet is away from the heater, so it is likely to be underheated. For this reason, due to uneven heating of the laminated sheet, there are problems that the state of the obtained molded product is different, the thickness is uneven and the strength is inferior, and the appearance is unsatisfactory. When a drawdown occurs in a sheet, there is a case where a wave phenomenon (called corrugation) occurs and a case where it does not occur. However, when a corrugation occurs, heating unevenness is further promoted, and the above problem due to heating unevenness is further increased. There is a risk of becoming.

  More recently, thermoforming machines having a short distance between the upper and lower heaters in the heating zone (about 200 to 300 mm) have also been used (the reason why a molding machine with a shorter distance between heaters is used is not certain). However, when such a molding machine is used, if the sheet drawdown increases, the lower surface of the sheet comes into contact with the lower heater in the heating zone, and the contacted surface is squeezed into a keloid, resulting in poor appearance. It was.

  One method for preventing drawdown includes a method of reducing the heat expansion force of the PSP constituting the laminated foam sheet. As one specific example, the time when the laminated foamed sheet is molded may be after two months or more after the production of the PSP constituting the laminated foamed sheet. However, this method has a problem in that a laminated foam sheet or PSP must be stocked for a long time after production, and the storage cost is high. On the other hand, there is also a method in which the PSP is expanded by extrusion foaming at a high temperature, thereby reducing the heating expansion force of the PSP early without incurring the above storage cost. However, PSP extruded and foamed at a high temperature has a problem that the strength of the PSP is lowered because the closed cell ratio is lowered, and consequently the strength of the molded product is also lowered.

  In addition, when the PSP is manufactured, the blow-up ratio is extremely increased, and the draw-down can be prevented by imparting a large heat shrinkability to the PSP. However, such PSP is not a preferable method because its thermoformability is extremely lowered, and a hole is easily formed in the thermoformed product or a crack is easily generated.

  Furthermore, the clamp interval of the conveying device that clamps and conveys both side edges of the laminated foam sheet can be expanded, and when the draw down occurs due to heating of the laminated foam sheet in the heating zone, the clamp interval is expanded, A method of absorbing drawdown is also conceivable. However, this method needs to be replaced with a special transport device different from the conventional transport device, and requires complicated work that requires controlling the expansion rate of the clamp interval according to the degree of drawdown, There is a problem that a special control device must be further added. Therefore, it can be said that this method in which a conventional thermoforming machine cannot be used as it is is a method that is difficult to adopt for those who have been using a general-purpose thermoforming machine.

  The present invention has been made in view of the above points, and effectively prevents the occurrence of drawdown in the heating zone during thermoforming even when molding is performed using a conventional general-purpose thermoforming machine. It is an object of the present invention to provide a container that is capable of being heated and having excellent physical properties and appearance, in which uneven heating and discoloration of the sheet are prevented, and is thermoformed using a styrene resin laminated foam sheet for thermoforming. .

The present invention is a container formed by thermoforming using a laminated foam sheet, wherein the laminated foam sheet used for thermoforming is between a styrene-based resin foam sheet and a stretched high impact polystyrene resin film. A laminated foam sheet of a styrene-based resin foam sheet and a high-impact polystyrene resin sheet , which is formed by laminating a melted high-impact polystyrene resin , and the high-impact polystyrene resin sheet is the stretched high-impact polystyrene resin film And a high-impact polystyrene resin layer, and has a laminated structure in which the high-impact polystyrene resin layer is laminated on the styrene-based resin foam sheet side, and is measured by peeling from the laminate foam sheet. High impact polystyrene resin The maximum value of the heat shrinkage load of the sheet is at least 10 g / 5 mm width in the longitudinal direction of the high impact polystyrene resin sheet, and the heat shrinkage rate of the laminated foamed sheet after heating at 145 ° C. for 40 seconds is styrene The gist is a container characterized in that it is 0 to 25% in both the extrusion direction and the width direction of the resin foam sheet, and the high impact polystyrene resin sheet is located on the outer surface side of the container.

  In the laminated foamed sheet used in the present invention, the maximum value of the heat shrinkage load of the high impact polystyrene resin sheet measured by peeling from the laminated foamed sheet is 11 g / 5 mm width at least in the longitudinal direction of the high impact polystyrene resin sheet. It is preferable that it is -20g / 5mm width. The high-impact polystyrene resin sheet is a laminated sheet of an unstretched high-impact polystyrene resin layer and a stretched high-impact polystyrene resin film, and the unstretched high-impact polystyrene resin layer side is on the styrene-based resin foam sheet side. It is preferable that they are laminated. Furthermore, the base resin of the styrene resin foam sheet is preferably a styrene resin having a Vicat softening point of 105 ° C. or lower. Or it is preferable that the lubricant is apply | coated to the surface of the high impact polystyrene resin sheet in the said styrene resin laminated foam sheet for thermoforming.

The laminated foam sheet used in the present invention can be stored for a long period of time before molding, as in the case of using a conventional styrene resin laminated foam sheet in which a HIPS sheet is laminated on a PSP during thermoforming. The occurrence of drawdown due to heating during thermoforming can be prevented without causing problems that reduce the physical properties of the sheet. The laminated foam sheet used in the present invention can effectively reduce or prevent the occurrence of drawdown even when the width is as large as about 1 m. It also contributes to improving the performance. Since the laminated foam sheet used in the present invention hardly causes drawdown, uneven heating during thermoforming hardly occurs. As a result, it is possible to provide the present invention which is a thermoformed container excellent in physical properties, appearance and the like. .
The greater the drawdown due to heating during thermoforming, the greater the surface area of the PSP, which causes the bubbles on the surface of the PSP to expand and become larger, not to mention the PSP side surface, which is the inner surface of the container, The smoothness of the HIPS sheet side surface is also reduced. Generally, when the surface smoothness is lowered, the printability (particularly curved surface printability) is inferior. On the other hand, since the laminated foam sheet used in the present invention is effectively improved in drawdown and its surface smoothness is prevented from deteriorating, the container of the present invention is excellent in printability. In particular, when the heat shrinkage load of the HIPS sheet is 11 g / 5 mm width to 20 g / 5 mm width at least in the longitudinal direction of the HIPS sheet, the occurrence of drawdown can be more effectively prevented. Also, even when using a thermoforming machine with a narrow heater-to-heater interval, it is very unlikely that the sheet will come into contact with the heater or hang down to the vicinity of the heater, so the sheet may be discolored or baked into a keloid. There is no possibility of causing a decrease in the appearance.

  Further, by extruding the melted HIPS between the PSP and the stretched HIPS film and laminating and integrating them, the laminated foam sheet HIPS sheet is divided into a stretched HIPS film and an unstretched HIPS layer. When configured and the unstretched HIPS layer is positioned on the PSP side, even if the thickness of the HIPS sheet is increased to some extent for the purpose of improving the impact resistance and strength of the container of the present invention, the PSP and the HIPS sheet As compared with the case where a single HIPS sheet stretched to PSP is thermally laminated, even if the thickness of the HIPS sheet is the same, low-cost manufacturing is possible.

  Furthermore, even if the container of the present invention is thermoformed by using a conventional general-purpose thermoforming machine as it is, it has effects such as exhibiting excellent properties.

  The laminated foam sheet used in the present invention is composed of PSP and HIPS sheet. As the styrenic resin as the PSP base resin, a styrene homopolymer, a styrene copolymer containing styrene as a main component, or a mixture thereof, or a group of the styrene homopolymer and the styrene copolymer. Examples thereof include a mixed resin in which one or two or more selected from the above are used as a main component and other resins or rubbers are mixed as subcomponents. Examples of the styrene copolymer include styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-butadiene copolymer, styrene- Examples thereof include a butadiene-acrylonitrile copolymer. Examples of the resin and rubber mixed as the subcomponent include polyphenylene oxide, butadiene rubber, and butadiene-styrene copolymer rubber.

  The styrenic resin preferably has a Vicat softening point (JIS K6870) of 105 ° C. or lower. Usually, a styrenic resin having a Vicat softening point of more than 105 ° C. is not preferable because a relatively large amount of a substance that reduces elongation during thermoforming of PSP is mixed or copolymerized. However, if the Vicat softening point is 105 ° C. or less, PSP thermoforming is possible even if a substance that lowers the elongation during thermoforming of PSP is mixed or copolymerized in the styrene resin. There is almost no fear of disturbing sex.

PSP supplies the above-mentioned styrenic resin, foaming agent, bubble regulator and, if necessary, various additives such as heat stabilizer, ultraviolet absorber, antioxidant, colorant, etc., into the extruder. Melt-knead at a temperature equal to or higher than the melting temperature of the resin, then extrude from an annular die and foam in an annular shape, expand the diameter of the annular foam while cooling, and then open the annular foam from one end along the extrusion direction Manufactured by a method of developing into a sheet shape. The PSP used in the present invention preferably has a thickness of 1.5 to 3.0 mm and a density of 0.75 to 0.15 g / cm ³ .

  As the foaming agent used in the production of the PSP, a volatile foaming agent, an inorganic gas-based foaming agent, a decomposable foaming agent, or the like is used alone or in combination of two or more. Examples of the volatile blowing agent include aliphatic hydrocarbons such as propane, normal butane, isobutane, pentane, and hexane, cyclic aliphatic hydrocarbons such as cyclobutane and cyclopentane, trichlorofluoromethane, dichlorodifluoromethane, 1 , 2-Dichloro-1,1,2,2-tetrafluoroethane, 1-chloro-1,1-difluoroethane, 1,1-difluoroethane, 1,1-dichloro-2,2,2-trifluoroethane, methyl Halogenated hydrocarbons such as chloride, ethyl chloride, and ethylene chloride. As the inorganic gas-based foaming agent, an inert gas such as carbon dioxide, nitrogen or air is used. Examples of the decomposable foaming agent include azodicarbonamide, dinitrosopentamethylenetetramine, azobisisobutyronitrile, sodium bicarbonate, and the like. However, from the viewpoint of improving secondary foamability during heating prior to thermoforming of PSP, it is desirable to use a volatile foaming agent as the main foaming agent. The amount of foaming agent added depends on the type of foaming agent, the base resin, the target foaming ratio, etc., so add the foaming agent so that the desired foaming ratio is obtained according to the type of foaming agent and base resin. Select the amount.

  Examples of the air conditioner used together with the foaming agent when PSP foams include inorganic powders such as talc and silica, acidic salts of polyvalent carboxylic acids, reaction mixtures of polyvalent carboxylic acids with sodium carbonate or sodium bicarbonate, and the like. Can be mentioned. The amount of the bubble regulator added is usually at most about 5 parts by weight per 100 parts by weight of the resin.

The base resin of the HIPS sheet laminated on the PSP consists of a styrene component and a rubber component. When the total of both is 100% by weight, the styrene component is 65 to 98% by weight, the rubber component is 35 to 2% by weight, Specifically, for example, the following can be mentioned.
(1) A random copolymer resin comprising a styrene component and a rubber component, a block copolymer resin, a graft copolymer resin, or a mixture of two or more of these copolymer resins.
(2) A mixture of the resin of (1) above and a styrene homopolymer.
(3) A mixture of styrene homopolymer and rubber (including thermoplastic elastomer).
(4) A mixture of the resin (1) or the resin (2) and rubber (including a thermoplastic elastomer).
However, in the styrenic resin as the base resin of the HIPS sheet, the value of Izod impact strength (JIS K6871) is 3. from the viewpoint of imparting impact resistance and imparting strength to the laminated foamed sheet and its thermoformed product. Those of 0 to 10 kg · cm · cm ⁻¹ , preferably 3.5 to 9 kg · cm · cm ⁻¹ should be used.

  In the laminated foam sheet used in the present invention, the HIPS sheet needs to have a maximum value of the heat shrinkage load of 10 g / 5 mm width or more in at least the longitudinal direction of the HIPS sheet (agreement with the extrusion direction). When the heat shrinkage load in the longitudinal direction of the HIPS sheet is less than 10 g / 5 mm width, the amount of the sheet drawn down is large during heating when the container is thermoformed using the laminated foam sheet, and as a result, as described above. Various problems may occur. In the longitudinal direction of the HIPS sheet, if the maximum value of the heat shrinkage load of the HIPS sheet has a width of 10 g / 5 mm or more, the drawdown of the laminated foam sheet when the container is thermoformed can be effectively reduced or prevented. Can do. In order to further reduce the drawdown of the laminated sheet, it is preferable that the maximum value of the heat shrinkage load at least in the longitudinal direction of the HIPS sheet is 11 g / 5 mm width or more. However, if this value is too large, there is a high risk that the sheet will come off the clamp when thermoformed using a laminated foam sheet, or that an elongation failure will occur during thermoforming, so the maximum value of the heat shrinkage load of the HIPS sheet is The width is preferably 20 g / 5 mm or less.

  In the laminated foam sheet used in the present invention, the heat shrinkage load of the HIPS sheet is the heat shrinkage load indicated by the HIPS sheet after being laminated on the PSP. The heat shrinkage load of HIPS is expressed by the stretching process at the time of manufacturing the HIPS sheet, but the heat shrinkage load before laminating HIPS on the PSP and the heat shrinkage load after laminating on the PSP are the same value. It is hard to be. The reason is that when HIPS and PSP are laminated, usually a method of lamination by thermal bonding is adopted, but the degree of orientation during stretching of the HIPS sheet is relaxed by the method of thermal bonding and the heating conditions at that time. It is thought that there are things. The degree of orientation relaxation during stretching of the HIPS sheet due to heating during lamination is also affected by the difference in thickness of the HIPS sheet. Therefore, in the laminated foam sheet used in the present invention, the heat shrinkage load of the HIPS sheet is the value after the HIPS is laminated on the PSP, and the heat shrinkage load of the HIPS sheet after lamination is the laminated sheet. The HIPS sheet is peeled off and measured.

  The surface layer part of PSP and the vicinity thereof are peeled off and adhered to the surface of the HIPS sheet peeled from the laminated sheet, and the heat shrinkage load can be measured using such a HIPS sheet as it is. In general, PSP is extruded and foamed into a cylindrical shape, and the cylindrical foam is manufactured so that its diameter is expanded while the surface is cooled. Therefore, the PSP surface is oriented by stretching. However, the degree of orientation is not so large. When the HIPS sheet is thermally bonded to the surface, the orientation of the PSP surface is relaxed to a state that can be almost ignored by the heat at that time. Therefore, it can be said that even if the measurement of the heat shrinkage load is performed while part of the PSP is peeled off and adhered to the surface of the HIPS sheet peeled from the laminated sheet, the measured value is not substantially affected.

  In order to measure the heat shrinkage load, a sample having a length of 15 mm and a width of 5 mm is cut out from the HIPS sheet peeled from the laminated sheet, and a thermomechanical analyzer (for example, a thermal mechanical analyzer manufactured by Shimadzu Corporation: TMA-50 type) ) Is fixed to the chuck at a longitudinal distance of 10 mm between the chucks (at this time, the ambient temperature is set to 30 ° C., and the initial load between the chucks on the sample is set to 6 g / 5 mm width). When heated at a rate of 10 ° C / minute and heated, the sample tends to shrink, but it is measured as the load necessary to prevent the sample from shrinking when the distance between chucks is always kept at 10 mm. The value to be applied is the heat shrinkage load. In the present invention, the maximum value (unit: g / 5 mm width) of the heat shrinkage load of the HIPS sheet is the maximum value among the heat shrinkage load values obtained by heating the sample from 30 ° C. to 150 ° C. (However, if noise appears near the maximum value of the temperature-heat shrinkage load curve obtained by heating the sample from 30 ° C to 150 ° C, the noise part passes through the center of the noise.) Correct with a curve and use the maximum value of the corrected curve.) In order to measure the heat shrinkage load in the longitudinal direction of the HIPS sheet, the longitudinal direction of the sample may be matched with the longitudinal direction of the HIPS sheet, and in order to measure the heat shrinkage load in the width direction of the HIPS sheet, the length of the sample is measured. The direction may be matched with the width direction of the HIPS sheet.

  As described above, the heat shrinkage load of the HIPS sheet is often different between before and after being laminated on the PSP, so the thermal bonding method and its conditions employed in the production of the laminated sheet, and the type and thickness of the HIPS sheet to be used. Depending on the degree of stretching, etc., it is important to know the tendency of the heat shrinkage load before and after lamination of the HIPS sheet on the PSP by conducting a preliminary experiment. If the tendency of the change in the heat shrinkage load of the HIPS sheet is grasped, it becomes easy to maintain the heat shrinkage load of the HIPS sheet after being laminated on the PSP within the scope of the present invention.

  The HIPS sheet used in the laminated foam sheet used in the present invention preferably has a thickness of at least 70 μm from the viewpoint of improving the impact resistance and strength of the present invention, which is a thermoformed product, Therefore, the upper limit of the thickness of the HIPS sheet is preferably 190 μm.

  In the laminated foam sheet used in the present invention, the heat shrinkage ratio of the laminated foam sheet after heating at 145 ° C. for 40 seconds corresponds to the extrusion direction of the PSP constituting the laminated foam sheet (the longitudinal direction of the laminated foam sheet coincides). In any of the width directions (corresponding to the width direction of the laminated foam sheet), it is necessary to be 0 to 25%. When the heat shrinkage ratio of the laminated foam sheet is smaller than 0% (when the measured value of the heat shrinkage ratio is negative, that is, when the sheet expands due to heating), when the laminated foam sheet is thermoformed, the heating zone On the other hand, if the laminated foam sheet has a large drawdown, and if the heat shrinkage rate exceeds 25%, the container, which is a thermoformed product, tends to crack during thermoforming. In order to further reduce the drawdown of the laminated foam sheet in the heating zone and further prevent cracking of the thermoformed product, the heat shrinkage rate of the laminated foam sheet is determined by the PSP extrusion direction (HIPS). It is preferably 3 to 15% for both the sheet extrusion direction and the width direction (matching the width direction of the HIPS sheet).

  The heat shrinkage rate of the laminated foam sheet is affected by the magnitude of the heat shrinkage load of the HIPS sheet constituting the laminated foam sheet, the degree of stretching of the PSP, the magnitude of the total pressure of the foaming agent and air in the PSP, and the like. . The larger the heat shrinkage load of the HIPS sheet, the greater the degree of stretching of the PSP, and the smaller the total pressure of the foaming agent and air in the PSP, the greater the heat shrinkage rate of the laminated foamed sheet, and vice versa. Becomes smaller. It is also affected by differences in PSP thickness, expansion ratio, and the like. Accordingly, the heat shrinkage load of the HIPS sheet before lamination, the total pressure of the foaming agent and air in the PSP, the degree of stretching of the PSP, and the heat shrinkage ratio of the laminated sheet after the HIPS sheet and PSP are laminated by preliminary experiments. It is important to know the relationship between the thermal expansion shrinkage and the expansion foam sheet with a heat shrinkage of 0 to 25%.

  For measurement of the heat shrinkage rate, an air circulation oven, for example, “PERFECT OVEN PH-200” (trade name) manufactured by Tabai Espec Co., Ltd. can be used. The heat shrinkage ratio was obtained by cutting out a square sample having a side of 20 cm from the laminated foam sheet with the thickness of the laminated foam sheet as it is, with the vertical and horizontal sides coinciding with the extrusion direction and the width direction of the PSP. The sample is lightly sandwiched from both sides with a coarse wire mesh (opening of about 1 to 2 cm), put in this state in an air circulation oven heated to 145 ° C. and heated for 40 seconds, then taken out of the oven and removed from each side of the sample. The length is measured and calculated from this measured value. The heat shrinkage rate of the laminated foam sheet is a value obtained by dividing the difference between the length before heating the sample (20 cm) and the length after heating by the length before heating and multiplying by 100. Calculation is performed for each of the direction that coincides with the extrusion direction and the direction that coincides with the width direction.

  In order to laminate the HIPS sheet on the PSP, the so-called thermal laminating method in which the HIPS sheet side is heated with a heating roll, and the HIPS sheet and the PSP are pressurized by the heating roll and the nip roll disposed on the PSP side to thermally bond them together. When the thickness of the HIPS sheet exceeds 50 μm, sufficient adhesive strength may not be obtained. As described above, since the HIPS sheet in the laminated foamed sheet constituting the present invention preferably has a thickness of at least 70 μm or more, the method for obtaining the laminated foamed sheet used in the present invention is more preferably PSP than the thermal lamination method. A method of extruding and laminating molten HIPS between the stretched HIPS films and laminating them is preferred. Hereinafter, a method for obtaining a laminated foam sheet by this method will be described with reference to the drawings.

  In FIG. 1, reference numeral 1 denotes PSP. Prior to laminating the HIPS sheet on PSP1, heat treatment for improving the formability of PSP1 (to relieve stress on the surface portion) can be performed as necessary. As a method for performing the heat treatment, a method is adopted in which PSP1 is wound around the surface of the heating roll 2 and heated, and the PSP1 is pressurized by the heating roll 2 and the pressure roll 3. PSP1 is heated in surface contact with heating roll 2 in the range from point A to point B, and an angle formed by a line segment connecting the center of heating roll 2 with points A and B: θ (this angle is defined as the holding angle) Is 20 to 180 ° for a 200 mm diameter heating roll, 15 to 150 ° for a 300 mm diameter heating roll, and 10 to 130 ° for a 400 mm diameter heating roll. Holding angle: θ can be adjusted by moving the tension rolls 4a, 4b up and down.

  In order to laminate the stretched HIPS film 5 on the PSP1 that has been heat-treated as described above, before the PSP1 and the HIPS film 5 are sandwiched between the pressure rolls 6a and 6b as shown in the figure, the PSP1 The HIPS 8 in the molten state is bonded to the HIPS film 5 by extruding the molten HIPS 8 from the extruder 7 into a sheet shape and pressing the PSP1 and the HIPS film 5 between the pressure rolls 6a and 6b. A laminated foamed sheet 9 can be obtained by laminating PSP1 and the HIPS film 5 as an agent.

  In the laminated foamed sheet 9 obtained by this method, the layer of the HIPS sheet in the laminated foamed sheet is a non-stretched or extruded layer composed of a stretched HIPS film 5 layer and a solidified product of molten HIPS8 used as an adhesive. The composite sheet is composed of a HIPS layer slightly stretched in the direction (hereinafter referred to as a substantially unstretched HIPS layer), and the substantially unstretched HIPS layer is positioned on the PSP1 side. Yes. In this case, the heat shrinkage load of the HIPS sheet is obtained by peeling the composite sheet of HIPS from the laminated foamed sheet 9 and measuring the composite sheet as described above. Accordingly, since the layer made of HIPS used as the adhesive is not practically stretched, in order to make the heat shrinkage load of the HIPS sheet (composite sheet) the above-mentioned value, as the HIPS film 5 It is necessary to use a stretched HIPS film.

  When the laminated foam sheet used in the present invention is manufactured by the extrusion lamination method as described above, the heat shrinkage load of the HIPS sheet in the obtained laminated foam sheet is expressed by the stretched HIPS film 5 or mainly by the HIPS film 5. Will be. Therefore, when the thickness of the HIPS film 5 to be laminated is too thin, it becomes difficult to obtain a desired heat shrinkage load value, and wrinkles are likely to occur in the HIPS film 5 during lamination. On the other hand, if the thickness of the HIPS film 5 is too thick, the cost becomes high. For this reason, as the stretched HIPS film 5 laminated | stacked by the said extrusion laminating method, the thickness is 15-50 micrometers, Especially the thing of 25-40 micrometers is preferable.

  In addition, when manufacturing a laminated foam sheet in the above-described extrusion laminating method, the pressure roll 6b on the side in contact with the HIPS film 5 out of the pair of pressure rolls 6a and 6b is preferably a cooled roll, and It is preferable that the PSP 1 and the HIPS film 5 are laminated using the HIPS 8 as an adhesive, and then the laminated sheet 9 is held by the cooled pressure roll 6b. If it does in this way, the fall of the orientation of the stretched HIPS film 5 can be made small. Further, from the same viewpoint, the extrusion position of the melted HIPS 8 is preferably a position slightly closer to the PSP1 side.

  The HIPS film 5 may be either a heat-treated surface or a non-heat-treated surface of PSP1, but when the HIPS film 5 is laminated on the non-heat-treated surface side of PSP1 as in the example shown in FIG. The slipperiness of the PSP side surface is also improved. If the present invention is thermoformed from such a laminated foam sheet, when a plurality are stacked and stored, and one by one is taken out from this state and used, the slipperiness between the containers is good. There is little possibility of troubles such as two or more being taken out by overlapping.

In order to improve the slip property of the present invention thermoformed from a laminated foam sheet, in addition to the method of heat treating the PSP side surface of the laminated foam sheet as described above, a lubricant such as silicon oil is added to the laminated foam sheet. A method of applying to one side or both sides is also effective. In particular, it is desirable to use both methods in order to make the PSP side surface of the laminated foam sheet more slippery. Thus, when using both methods together, the heat processing of the PSP side surface of a laminated foam sheet is usually preceded.
In particular, when a lubricant such as silicon oil is applied to the HIPS film 5 side of the laminated foam sheet, in addition to the effect of improving slipperiness, the effect of improving printability is also imparted. Therefore, it is very effective when printing is performed on the surface of the HIPS film 5 of the container of the present invention which is thermoformed so that the HIPS film 5 side of the laminated foam sheet is the outer surface side.

  In addition, a lubricant such as silicon oil is usually diluted with water, applied to the surface of the laminated foamed sheet by a roll coater, and dried. This drying may be carried out after winding the laminated foam sheet into a roll after application.

  In the present invention, the laminated foamed sheet is heated and softened in a heating zone, and then molded by a conventional method. Forming methods include vacuum forming, pressure forming, and applications such as free drawing, plug and ridge forming, ridge forming, matched mold forming, straight forming, drape forming, reverse draw forming, air slip forming, Plug-assist molding, plug-assist reverse load molding, or a combination of these is employed.

Hereinafter, the present invention will be described in more detail with reference to examples.
A PSP is sequentially drawn out from a roll body in which a PSP (width 1040 mm) having a thickness of 2.3 mm and a basis weight of 250 g / m ² is wound in a roll shape using polystyrene having a Vicat softening point of 100 ° C. as shown in FIG. According to the method, the PSP is brought into contact with the heating roll 2 having a diameter of 400 mm, and the PSP is pressurized by the pinching roll 3 (without a temperature control mechanism) at a substantially intermediate point where the PSP is in contact with the heating roll 2. . The processing conditions are as follows.

(1) Central temperature of heating roll surface: 143 ° C
(2) End temperature of heating roll surface: 139 ° C
(3) Heating roll has a circumferential speed of 34.4 m / min (4) Holding angle of PSP to heating roll (θ): 110 °
(5) Contact length of PSP to heating roll: 384 mm
(6) PSP contact time with heating roll 0.67 seconds (7) PSP clamping pressure: 5.3 kg / cm

  The interval between the heating roll 2 and the pinching roll 3 was set to 1.3 mm when the PSP was not passing, and 1.8 mm when the PSP was passing. The thickness of PSP after performing the said heating and pressurization was 2.3-2.4 mm.

  Next, the melted HIPS is extruded from an extruder between the PSP surface not subjected to heat treatment and a stretched HIPS film having a thickness of 35 μm (trade name “Styrophan HSR” manufactured by Oishi Sangyo Co., Ltd.). (Extruded after adjusting so that the thickness after lamination was 105 μm), PSP and the stretched HIPS film were pressed with a pinching roll and laminated. In the obtained laminated foamed sheet, the total thickness of the stretched HIPS film and the layer of HIPS used as the adhesive (thickness as the entire HIPS sheet) was 140 μm.

  Table 1 shows the heat shrinkage rate in the PSP extrusion direction and the width direction of the obtained laminated foam sheet, and the heat shrinkage load of the HIPS sheet measured by peeling the HIPS sheet from the laminated foam sheet.

(Table 1)

  From the roll body obtained by winding the laminated foam sheet obtained as described above, the laminated foam sheet is sequentially fed out with the HIPS sheet side facing up so that the HIPS sheet surface side of the laminated foam sheet is located on the outer surface side of the container. The container was continuously thermoformed. The laminated foam sheet is heated for 12 seconds until the temperature of the laminated foam sheet surface reaches about 120 ° C. by heaters (distance between heaters: 300 mm) provided in the heating zone of the molding machine above and below the laminate sheet. And then molded to obtain a container. Table 1 shows the drawdown amount generated in the laminated foam sheet when the laminated foam sheet is heated in the heating zone, and the surface state inside the thermoformed container. The number of containers taken per shot in this molding was 6 in the length direction and 6 in the width direction of the laminated foam sheet. The container obtained by molding has an inner diameter of the opening of about 14.2 cm (the outer diameter including the lip is about 15 cm) and the bottom has an inner diameter of about 9.2 cm (the outer diameter is about 9.8 cm). It is a circular container. The center line average roughness (JIS B0601) on the outer surface side (HIPS sheet side) of the obtained container was measured with a surface roughness measuring instrument “Surfcoder SE-30D” manufactured by Kosaka Laboratory. The measurement place measured the place near the perpendicular | vertical of the container side wall outer surface at the distance of 8 mm up and down. The values measured for each one of the 36 containers for one shot were averaged, and these values are shown in Table 1.

* 1: Since the initial load value was below when heated, the initial load value was indicated.
* 2: When the laminated foam sheet is heated by placing the laminated foam sheet at the middle position between the upper and lower heaters, and the draw down occurs in the laminated foam sheet, it is the original position of the laminated foam sheet and the bottom surface of the sheet that hangs down due to the draw down The distance between the parts is shown.

Comparative Example 1
PSP similar to Example 1 was heat-treated in the same manner, and then the HIPS melted from the extruder was extruded to the surface of the PSP not subjected to the heat treatment, and a HIPS sheet having a thickness of 140 μm was laminated on the PSP surface. . Table 1 shows the properties of the laminated foam sheet, the sheet drawdown amount in the heating zone when the laminated foam sheet is thermoformed in the same manner as in Example 1, and the surface state of the laminated foam sheet after heating. Showed. Further, the center line average roughness on the outer surface side of the container obtained by thermoforming the laminated foam sheet was measured in the same manner as in Example 1, and the results are shown in Table 1. In addition, since there is a portion drooped in a keloid shape on a part of the sheet surface due to drawdown during heating of the laminated foam sheet in Comparative Example 1, the average roughness of the outer surface of the container obtained by thermoforming this laminated foam sheet The measurement was performed avoiding the portion drooping in keloid form.

It is process schematic which shows the manufacture example of the laminated foam sheet used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Styrenic resin foam sheet 5 High impact polystyrene resin film 8 Molten high impact polystyrene resin 9 Laminated foam sheet

Claims (5)

A high-impact container in which the laminated foam sheet used for thermoforming is melted between a styrene resin foam sheet and a stretched high-impact polystyrene resin film. A laminated foam sheet of a styrene-based resin foam sheet and a high-impact polystyrene resin sheet formed by extruding a polystyrene resin, wherein the high-impact polystyrene resin sheet is the stretched high-impact polystyrene resin film and high-impact polystyrene. A high impact polystyrene resin which is a composite sheet comprising a resin layer and has a laminated structure in which the high impact polystyrene resin layer is laminated on the styrene resin foam sheet side and is measured by peeling off the laminate foam sheet Add sheet The maximum value of the shrinkage load is at least 10 g / 5 mm width in the longitudinal direction of the high impact polystyrene resin sheet, and the heat shrinkage rate of the laminated foamed sheet after heating for 40 seconds at 145 ° C. is that of the styrene resin foamed sheet. It is 0 to 25% in both the extrusion direction and the width direction, and the high-impact polystyrene resin sheet is located on the outer surface side of the container.   The maximum value of the heat shrinkage load of the high impact polystyrene resin sheet measured by peeling from the laminated foam sheet is 11 g / 5 mm width to 20 g / 5 mm width at least in the longitudinal direction of the high impact polystyrene resin sheet. The container according to claim 1.   The high-impact polystyrene resin sheet is a laminated sheet of an unstretched high-impact polystyrene resin layer and a stretched high-impact polystyrene resin film, and the unstretched high-impact polystyrene resin layer side is laminated on the styrene resin foam sheet side The container according to claim 1 or 2, wherein the container is formed.   The container according to any one of claims 1 to 3, wherein the base resin of the styrene resin foam sheet is a styrene resin having a Vicat softening point of 105 ° C or lower.   The container according to any one of claims 1 to 4, wherein a lubricant is applied to a surface of the high-impact polystyrene resin sheet in the styrene resin laminated foam sheet for thermoforming.

Images