JP6317979B2 - Polystyrene resin foam - Google Patents

Description

  The present invention relates to a novel polystyrene-based resin laminate foam having a plurality of streaks on the surface.

  Polystyrene resin foams are excellent in light weight, heat insulation, thermoformability, and machinability, so they can be used for food logistics packaging materials such as tray containers, instant noodle containers, lunch boxes, and natto containers. Widely used as a thermoforming foam for processing.

  Among them, polystyrene resin foams for thermoforming that have a textured appearance on the surface are excellent in design and have a high-class feel. ing.

  Conventionally, as such polystyrene-based resin foams, for example, the following (1) to (3) are known.

(1) A pattern printed directly on the surface of a polystyrene resin foam (Patent Document 1).
(2) A film on which a pattern is printed is laminated on the surface of a polystyrene resin foam with an adhesive or the like (Patent Document 2).
(3) The polystyrene resin foam layer B colored on the surface of the polystyrene resin foam A is laminated in a streak shape or a strip shape by a coextrusion method (Patent Document 3).

JP 2007-7966 A Japanese Patent Laid-Open No. 5-38752 JP 2003-94896 A

  However, as in (1), the pattern directly printed on the surface of the foam has a problem in that its use is limited because the printed surface may be in direct contact with the package.

  In addition, since the manufacturing requires two steps, a foam manufacturing process and a pattern printing process, the manufacturing process becomes complicated and the manufacturing cost is high.

  In addition, as in (2), a film with a pattern printed on the surface of the foam is laminated with an adhesive, although the printed surface does not touch food directly, it may be difficult to recycle, It left room for further improvement.

  In addition, the manufacturing process requires a foam manufacturing process, a film manufacturing process, a pattern printing process on the film, and a process in which the foam and the pattern-printed film are bonded together. And problems in terms of manufacturing costs.

  In addition, the foamed layer co-extruded in the shape of a streak or strip as shown in (3) has a structure in which a strip-shaped foam layer is laminated on the foam core layer. In some cases, it is difficult to print beautifully when a trademark or a component label is printed using the laminated surface as a non-food contact surface.

  Thus, conventional polystyrene-based resin laminated foams such as sheet-like foams having a streak pattern each have problems, and thus have excellent appearance and satisfy surface smoothness, printability, and the like. The development of a practical polystyrene-based resin laminated foam has been eagerly desired, but no satisfactory proposal has been made yet.

  The present invention has been made in view of the circumstances as described above, has a processing characteristic equivalent to that of a conventional polystyrene resin foam, has a beautiful streak pattern, and has surface smoothness and printing. It is an object to provide a polystyrene-based resin laminated foam that is excellent in properties and the like, and that is easy to manufacture and inexpensive.

  According to this invention, the polystyrene-type resin laminated foam as described in the following <1>-<4> is provided.

<1> A polystyrene resin laminate foam in which a polystyrene resin layer is laminated by coextrusion on at least one surface of a polystyrene resin foam layer, and the polystyrene resin layer is formed in a streak shape in the extrusion direction. The plurality of polystyrene resin layers are continuous in the width direction, and the resin layers adjacent in the width direction are formed as different layers, and the apparent density of the polystyrene resin laminated foam is 0.04 to A polystyrene-based resin laminate foam having a total basis weight of 0.21 g / cm ³ and a total basis weight of the polystyrene-based resin layer of ² to 100 g / m ² .
<2> The thickness of the polystyrene-based resin laminate foam is 0.5 to 10 mm, and the basis weight of the polystyrene-based resin laminate foam is 70 to 600 g / m ^2. Polystyrene resin laminate foam.
<3> The polystyrene resin laminated foam according to <1> or <2>, wherein the maximum height of the contour curve of the surface of the polystyrene resin layer of the polystyrene resin laminated foam is 20 μm or less. body.
<4> The plurality of polystyrene-based resin layers are formed of two types of resin layers formed in stripes in the extrusion direction , and the resin layers are alternately and continuously formed in the width direction, and at least one of the resin layers The polystyrene-based resin laminated foam according to any one of <1> to <3>, wherein a colorant is blended.

  In the polystyrene-based resin laminated foam of the present invention, a plurality of resin layers are laminated on at least one surface of the polystyrene-based resin foam layer and are formed in a streak shape in the extrusion direction, and the plurality of resin layers are continuous in the width direction. Therefore, it is possible to provide a polystyrene-based resin laminate foam that is excellent in surface smoothness and printability, and that is simple and inexpensive to manufacture. Moreover, when a coloring agent etc. are mix | blended with the resin layer, it has a streak pattern on the surface of a laminated foam, and it becomes the thing excellent in the external appearance.

  Therefore, the polystyrene-based resin laminated foam of the present invention is a sheet-like foam for thermoforming such as tray containers, instant noodle containers, lunch boxes, natto containers and food logistics packaging materials such as rice cakes, lunch boxes and confectionery. Demand is widely expected as plate-like foams such as boxes and folded boxes.

It is explanatory drawing of the typical polystyrene-type resin laminated foam of this invention. It is a schematic sectional drawing of the polystyrene-type resin laminated foam of this invention. It is another example of the schematic sectional drawing of the polystyrene-type resin laminated foam of this invention. It is explanatory drawing of the manufacturing method of the typical polystyrene-type resin laminated foam of this invention. It is explanatory drawing of the typical cyclic | annular die | dye used by this invention. It is explanatory drawing of the laminated part in the typical cyclic | annular die used by this invention. It is shape explanatory drawing which looked at the lamination | stacking part flow-path hole in the typical cyclic | annular die used by this invention from the V direction. It is shape explanatory drawing which looked at the lamination | stacking part flow-path hole in the typical cyclic | annular die used by this invention from the V direction. It is shape explanatory drawing which looked at the lamination | stacking part flow-path hole in the typical cyclic | annular die used by this invention from the V direction.

[Polystyrene resin laminated foam]
FIG. 1 is an explanatory view of a representative polystyrene resin laminated foam 1 (hereinafter simply referred to as a laminated foam 1) according to the present invention, and FIG. 2 is a schematic sectional view of the laminated foam 1 in the thickness direction. It is.

  In the laminated foam 1, a plurality of polystyrene resin layers are laminated by coextrusion on one side of a polystyrene resin foam layer 2 (hereinafter simply referred to as a foam layer 2), and the plurality of resin layers are in the extrusion direction. Are laminated on the foam layer in a streak-like manner and in a continuous state in the width direction. For example, as shown in FIGS. 1-3, with respect to the foamed layer 2, the polystyrene-type resin layer (I) 3 containing a coloring agent (henceforth abbreviated as resin layer (I) hereafter) and the polystyrene-type resin layer (II) 4 (hereinafter, simply referred to as “resin layer (II)”) are laminated in a streak-like manner in the extrusion direction and are laminated in a continuous state in the width direction.

  Here, in the present invention, for example, as shown in FIG. 1, a streak is a line or a band having a certain width or changing the width along the longitudinal direction (extrusion direction) of the foam. For example, it is discriminated as a streak pattern based on the difference in color of the plurality of resin layers, and a wood grain pattern, a stripe pattern, and a blurring pattern in which the color tone changes in stages are given to the foam. Note that the difference in color means that the hue, hue, brightness, and saturation are different and can be visually recognized.

  In the laminated foam 1, a plurality of polystyrene resin layers are laminated on at least one surface of the foamed layer 2 in a state of being continuous in the width direction in the extrusion direction by a coextrusion. Since the plurality of polystyrene resin layers are formed in a streak shape in the extrusion direction, the laminated foam 1 forms a streak pattern and is particularly excellent in appearance. Furthermore, as shown in FIGS. 2 and 3, the plurality of polystyrene resin layers are continuously formed in the width direction, thereby improving the smoothness of the surface of the laminated foam. Conventionally, when the resin layer is not continuously formed, when the resin layer portion is laminated on the foam layer by coextrusion, the heat of the resin layer portion inhibits foaming on the surface of the foam layer. There was a possibility that the smoothness of the foam surface would be reduced. In the present invention, since the resin layer is continuously formed in the width direction, it is considered that the smoothness of the surface of the laminated foam is improved and the printability of the laminated foam is improved. From the above viewpoint, it is preferable that the resin layer is continuously formed on the entire surface in the width direction of the foam (excluding the end portion), and the resin layer is more uniformly formed in the width direction. preferable.

  In addition, when several polystyrene type resin layers consist of two types of resin layers, it is preferable that resin layers are continuously formed alternately in the width direction. Also, the resin layer can be made of three or more types of resin layers. In this case, the resin layer adjacent to a certain resin layer is formed as a different resin layer and continuously formed in the width direction. It is preferable.

  The plurality of resin layers may be in a foamed state or in a non-foamed state, but in order to obtain a laminated foam having a clear pattern in the plurality of resin layers, the resin layer is in a non-foamed state. It is preferable that In the non-foamed resin layer, some bubbles may be locally formed.

<Resin layer (I) 3 and resin layer (II) 4>
The plurality of resin layers are not particularly limited as long as a plurality of resin layers that can be discriminated by different characteristics such as color, physical properties, and performance are formed. 1, it is preferable that the resin layer (I) 3 and the resin layer (II) 4 can be distinguished by different colors as shown in FIG. Moreover, it is preferable that the coloring agent is mix | blended with at least one resin layer, and the colored resin layer is formed. In the present invention, the resin layer (I) 3 and the resin layer (II) 4 will be described assuming that the resin layer (II) 4 has higher brightness.

  Resin layer (I) 3 and resin layer (II) 4 consist of a resin melt for forming resin layer (I) 3 containing a polystyrene resin, a colorant, preferably a plasticizer and other additives, and a polystyrene resin. The resin melt for forming the resin layer (II) 4 preferably blended with a plasticizer and other additives is formed into a resin melt for forming the foamed layer in a state of being continuous in the width direction in a coextrusion die. It is formed in a streak shape by laminating and coextrusion. In addition, although resin layer (II) 4 does not contain a coloring agent as an essential component, a coloring agent can also be mix | blended as needed.

  Below, each component of the material used in order to form a some resin layer is explained in full detail. In addition, it is preferable to use the same material for the resin layer (II) 4 and the resin layer (I) 3 from the viewpoint of forming a more uniform resin layer.

(Polystyrene resin)
Examples of the polystyrene resin constituting the resin layer include polystyrene (GPPS), impact-resistant polystyrene (HIPS), styrene-acrylonitrile copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, and styrene. -A methyl methacrylate copolymer, a styrene-maleic anhydride copolymer, a polystyrene-polyphenylene ether copolymer, etc. are illustrated.

  In addition, for the polystyrene resin, depending on the desired purpose, polyphenylene ether resin, propylene homopolymer, polypropylene resin such as ethylene-propylene copolymer, polyethylene resin such as high density polyethylene, low density polyethylene, A material containing a polymer such as a thermoplastic elastomer such as a styrene-conjugated diene block copolymer or a hydrogenated product thereof, or a rubber such as ethylene-propylene rubber or butadiene rubber can be used. The proportion is preferably 40% by weight or less in the polystyrene resin, more preferably 20% by weight or less, and further preferably 10% by weight or less.

  As the polystyrene resin constituting the resin layer, for example, the melt viscosity η1 is preferably 600 to 1400 Pa · s, more preferably 700 to 1300 Pa · s, and still more preferably 800 to 1200 Pa · s. Is desirable. From the viewpoint of forming a uniform resin layer, it is preferable to use a polystyrene-based resin constituting the plurality of resin layers having a value closer to the above-described melt viscosity.

(Coloring agent)
As the colorant, inorganic or organic pigments or dyes can be used. Examples of organic pigments include, for example, condensed azos such as monoazo and chromoftal red, anthraquinone, isoindolinone, heterocyclic, perinone, quinacridone, perylene, thioindigo, dioxazine, and phthalocyanine Nitroso, phthalocyanine pigments, organic fluorescent pigments, and the like.

  Examples of inorganic pigments include titanium oxide, carbon black, titanium yellow, iron oxide, ultramarine blue, cobalt blue, calcined pigment, metallic pigment, mica, pearl pigment, zinc white, precipitated silica, cadmium red and the like. .

  Examples of the organic dye include anthraquinone, heterocyclic, perinone, basic dye, acid dye, and mordant dye. Among these, the use of an inorganic pigment is preferable because it can be produced at low cost.

  Moreover, a coloring agent may be used individually by 1 type, and 2 or more types may be mixed and used for it. Incidentally, by using iron oxide or a tea-based colorant containing iron oxide as a colorant, for example, a colorant composed of a mixture of iron oxide, carbon black, and titanium oxide, the resin layer (I) 3 is made of a tea-based material. It is possible to obtain a laminated foam 1 that has a color, has a wood-tone or grid-like pattern, and has a higher design and a high-class feeling.

  Moreover, when using for a food container, it is preferable to select and use a polyolefin hygiene council registered product from the above.

(Antistatic agent)
As the antistatic agent, a conventionally known polymer type antistatic agent, surfactant type antistatic agent or the like is used. From the viewpoint of antifouling property or durability of the antistatic effect, the polymer type antistatic agent Is preferably used. The polymer antistatic agent includes a resin having a surface resistivity of less than 1 × 10 ¹² Ω, and specifically, an alkali metal selected from the group consisting of potassium, rubidium and cesium as metal ions. It is preferable to use an ionomer resin containing or a hydrophilic resin such as polyetheresteramide or polyether as a main component. In addition, an antistatic agent can be mix | blended with both resin layer (I) and resin layer (II), and can also be mix | blended with both.

(Other additives)
As a material component for molding a plurality of resin layers, various additives can be added in addition to the above components. Examples of the additive include an antioxidant, a heat stabilizer, a weathering agent, an ultraviolet absorber, a flame retardant, a filler, an antibacterial agent, and the like.

<Foaming layer 2>
The foam layer 2 is formed by coextrusion foaming a foam layer forming melt containing a polystyrene-based resin, a physical foaming agent, a cell regulator and other additives. Below, each component of the material used in order to shape | mold the foaming layer 2 is explained in full detail.

(Polystyrene resin)
There is no restriction | limiting in particular as polystyrene-type resin which comprises the foamed layer 2, The thing similar to the above-mentioned polystyrene-type resin which comprises the resin layer can be used.
The melt viscosity η2 of the polystyrene resin constituting the foamed layer is preferably 800 to 2000 Pa · s, more preferably 1000 to 1700 Pa · s, and further preferably 1200 to 1500 Pa · s. If it is in the said range, a favorable foamed layer can be formed.

(Other additives)
As a material component for forming the foam layer 2, various additives can be added in addition to the above components. Examples of the additive include an antioxidant, a heat stabilizer, a weathering agent, an ultraviolet absorber, a flame retardant, an inorganic filler, an antibacterial agent, a colorant, and an antistatic agent. In addition, when mix | blending a coloring agent, it is desirable to adjust the kind and compounding quantity of a coloring agent so that it may become lighter than resin layer (I) from a viewpoint of improving the texture of a foam.

  Hereinafter, the laminated foam 1 in which a plurality of resin layers are laminated on the surface of the foam layer 2 by coextrusion will be described in detail.

[Maximum height of contour curve on the surface of laminated foam 1]
The maximum height of the contour curve on the surface of the laminated foam 1 is 20 μm or less, preferably 10 μm or less. In the present invention, since a plurality of resin layers are continuously formed in the width direction on the surface of the foam layer, the maximum height of the contour curve of the foam surface on the laminated surface side of the polystyrene resin layer is low. Thus, the printability of the laminated foam is improved.

  The maximum height of the contour curve on the surface of the laminated foam 1 is the width of the foam surface formed by a foam layer and a plurality of resin layers on the surface of the laminated foam 1 in accordance with JIS B0601 (2001). It is specified as the height of the contour curve element of the unevenness in the direction. Specifically, it can be measured using a surf coder SE1700α manufactured by Kosaka Laboratory Ltd.

[Basis weight difference in the width direction of the laminated foam 1]
The difference between the maximum and minimum basis weights of the foam sample for each width of 2 mm in the 50 mm foam continuous in the width direction (TD direction) of the laminated foam 1 is preferably 20 g / m ² or less. In the present invention, a plurality of resin layers are continuously formed in the width direction. However, since the resin layers having substantially the same basis weight are laminated among the plurality of resin layers, the basis weight in the width direction of the laminated foam 1 is laminated. The change in quantity is small. From the above viewpoint, the basis weight difference in the width direction of the laminated foam 1 is preferably 15 g / m ² or less, more preferably 10 g / m ² or less.

[Basis weight of laminated foam 1]
The basis weight of the laminated foam 1 is 70 to 600 g / m ² , preferably 100 to 500 g / m ² , more preferably 120 to 400 g / m ² . By setting the basis weight within the above range, it is possible to obtain the laminated foam 1 having rigidity and excellent lightness.

As a method for measuring the basis weight of the laminated foam 1, a test piece having a width of 250 mm was cut out over the entire width of the laminated foam 1, and the weight (g) of the test piece was determined as the area of the test piece (foam width (mm ) × 250 mm) and converted to the weight (g) of the laminated foam 1 per 1 m ² , the basis weight (g / m ² ) of the laminated foam 1 can be obtained.

[Apparent density of laminated foam 1]
The apparent density of the laminated foam 1 is preferably 0.04 to 0.35 g / cm ³ . When the apparent density is within the above range, the balance between lightness and strength is excellent. The lower limit of the apparent density is more preferably 0.05 g / cm ^3, most preferably from 0.07 g / cm ^3. On the other hand, the upper limit of the apparent density is more preferably 0.21 g / cm ³ , and still more preferably 0.15 g / cm ³ .

[Thickness of laminated foam 1]
The thickness of the laminated foam 1 is not particularly limited, but is 0.5 to 15 mm, preferably 0.6 to 10 mm, and more preferably 0.7 to 5 mm. By making the thickness of the laminated foam 1 within this range, a tray container, instant noodle container, bento container, natto container, frozen container, rice cake, etc., which are thermoformed and provided with a streak pattern and full of high-quality design It can be suitably used as a food container or the like, or as a folded box or a display core.

Next, an embodiment of the method for producing a foam of the present invention will be described in detail with reference to FIG.
As shown in FIG. 4, the foam production method of the present invention is first made of polystyrene resin 11, which is a material for forming the foamed layer 2 described above, and other bubble adjustments added as necessary. An additive such as an agent is supplied to the first extruder 14 and heated and kneaded, and the physical foaming agent 12 is press-fitted and further kneaded to obtain a resin melt 13 for forming a foam layer in the first extruder 14.

(Physical foaming agent)
Examples of the physical foaming agent include aliphatic hydrocarbons having 2 to 7 carbon atoms, such as ethane, propane, normal butane, isobutane, normal pentane, isopentane, isohexane, cyclohexane, heptane, methyl chloride, ethyl chloride, 1, Halogenated aliphatic hydrocarbons having 1 to 4 carbon atoms such as 1,1,2-tetrafluoroethane and 1,1-difluoroethane, and aliphatic alcohols having 1 to 4 carbon atoms such as methanol, ethanol, propanol and butanol Or organic physical foaming agents such as aliphatic ethers having 2 to 8 carbon atoms such as dimethyl ether, diethyl ether and dipropyl ether, and inorganic physical foaming agents such as nitrogen, carbon dioxide and water.

  These physical foaming agents may be used individually by 1 type, and may use 2 or more types together. Moreover, what has a normal butane, isobutane, or these mixtures as a main component can be used suitably from a viewpoint of compatibility with a polystyrene-type resin and foaming efficiency.

  The amount of the physical foaming agent added can be appropriately adjusted according to the apparent density of the foam, but is usually 0.15 to 1.8 mol with respect to 1 kg of polystyrene resin for forming the foamed layer 2. It is preferable that it is 0.3 to 1.5 mol, more preferably 0.4 to 1.2 mol. In addition to the physical foaming agent, a chemical foaming agent may be used in combination as the foaming agent.

(Bubble conditioner)
As the bubble adjusting agent, either an organic type or an inorganic type can be used. Examples of the inorganic air conditioner include metal borates such as zinc borate, magnesium borate, borax, sodium chloride, aluminum hydroxide, talc, zeolite, silica, calcium carbonate, sodium bicarbonate and the like. .

  Examples of the organic foam regulator include sodium phosphate-2,2-methylenebis (4,6-tert-butylphenyl), sodium benzoate, calcium benzoate, aluminum benzoate, and sodium stearate. Can do. Also, a combination of citric acid and sodium bicarbonate, an alkali salt of citric acid and sodium bicarbonate, or the like can be used. These bubble regulators may be used alone or in combination of two or more.

  The addition amount of the cell regulator is preferably 0.05 parts by weight or more and 10 parts by weight or less, more preferably 0.2 parts by weight or more and 5 parts by weight or less per 100 parts by weight of the polystyrene-based resin for forming the foamed layer 2. Range.

  Separately, a polystyrene resin 5 and a colorant 7, which are materials for forming the resin layer (I) 3 described above, are supplied to the second extruder 15 as necessary, and other additives. The volatile plasticizer 8 is supplied as necessary and further kneaded to obtain a resin melt 9 for forming the resin layer (I) in the second extruder 15.

  Furthermore, the polystyrene resin 6 that is a material for forming the resin layer (II) 4 described above, and other additives added as necessary are supplied to the third extruder 16 and kneaded, Further, if necessary, the volatile plasticizer 8 is supplied and further kneaded to obtain the resin melt 10 for forming the resin layer (II) in the third extruder 16. At this time, a colorant for making the resin layer (II) 4 have a color tone different from that of the resin layer (I) 3 may be added.

(Plasticizer)
In order to form the resin layer (I) 3 and the resin layer (II) 4, a plasticizer may be added. By adding a plasticizer, the resin layer (I) forming melt, the resin layer (II) forming melt, and the foam layer forming melt are co-extruded with the resin layer at an appropriate foaming temperature. (I) The melt elongation of the forming melt and the resin layer (II) forming melt can be remarkably improved, and the elongation of the resin layer forming melt can be changed to the elongation of the polystyrene resin foam layer forming resin melt. The resin layer can be formed more easily.

  As the plasticizer, a volatile plasticizer is preferably used. The volatile plasticizer is suitable for coextrusion by reducing the melt viscosity of the polystyrene resin when it is present in the resin melt for forming the resin layer (I) and the resin melt for forming the resin layer (II). A resin melt for forming a resin layer can be formed, and after extrusion foaming, it can be volatilized from the resin layer and easily removed from the resin layer. Therefore, by using a volatile plasticizer, the plasticizer blended in the resin layer is preferable from the viewpoint of food hygiene without contact with food.

  In addition, a volatile plasticizer is preferably used because the plasticizer remains after co-extrusion and there is no possibility of reducing the rigidity of the resin layer (I) 3 and the resin layer (II) 4.

  In addition, if it is the addition amount of the grade which does not produce the physical property fall of the polystyrene-type resin which forms resin layer (I) 3 and resin layer (II) 4, a normal plasticizer can also be used, The addition amount is Preferably it is less than 3% by mass, more preferably less than 2%.

  Examples of the volatile plasticizer include aliphatic hydrocarbons having 2 to 7 carbon atoms, halogenated aliphatic hydrocarbons having 1 to 3 carbon atoms, aliphatic alcohols having 1 to 4 carbon atoms, or 2 to 8 carbon atoms. Those composed of one or more selected from the following aliphatic ethers are preferably used.

  The boiling point of the volatile plasticizer is preferably 120 ° C. or lower, more preferably 80 ° C. or lower, from the viewpoint of volatility from the resin layer. If the boiling point of the volatile plasticizer is within this range, the co-extruded product is left in the state where the resulting foam is left, and the volatile plasticizer is resin due to heat immediately after coextrusion or gas permeation at room temperature. Naturally stripped from the layer and removed naturally. The lower limit of the boiling point is approximately -50 ° C.

  The addition amount of the volatile plasticizer is preferably 0.15 to 1.4 mol / kg, more preferably 0.2 to 1.2 mol / kg with respect to the polystyrene resin. By making the addition amount within this range, it can be melted well during production.

  Then, the foamed layer forming resin melt 13, the resin layer (I) forming resin melt 9, and the resin layer (II) forming resin melt 10 are introduced into an annular die 17, joined, laminated, and coextruded. Thus, the laminated foam 1 is obtained.

  The coextrusion of the resin melt 13 for forming the foam layer, the resin melt 9 for forming the resin layer (I), and the resin melt 10 for forming the resin layer (II) will be described in detail below.

(Coextrusion of resin melt 13 for forming foam layer, resin melt 9 for forming resin layer (I) and resin melt 10 for forming resin layer (II))
After the resin melt 13 for forming the foam layer, the resin melt 9 for forming the resin layer (I), and the resin melt 10 for forming the resin layer (II) are adjusted to appropriate temperatures as described later, the annular die 17 is introduced.

  A plurality of resin layers (I) forming resin melt 9 and resin layer (II) forming resin melt 10 in the annular die 17 are formed on the outer peripheral surface of the foam layer forming resin melt 13 in the extrusion direction. The resin layer is formed on the surface of the foamed layer 2 by co-extrusion and foaming the foamed layer forming resin melt 13 after being joined and laminated in a state of being alternately continuous in the width direction so as to form a streaky shape. (I) 3 and the resin layer (II) 4 produce the cylindrical laminated foam in which the stripe direction was continuously formed alternately in the width direction.

  If the resin layer (I) 3 and the resin layer (II) 4 can be joined and laminated in a state where both are continuous in the width direction, even if a plurality of resin layers are laminated at the same time, the joining position is shifted sequentially. For example, as shown in FIGS. 5 and 6, the method of simultaneously merging and laminating is preferable because the merging and laminating can be performed with high accuracy.

  Specifically, as shown in the enlarged view of the vicinity of the laminated portion V in FIG. 6, the laminated component Z in which the channel holes are alternately provided on both surfaces in the vicinity of the merged laminated portion V with the foamed layer forming resin melt 13. The resin melt 9 for forming the resin layer (I) is supplied from one side of the resin, and the resin melt 10 for forming the resin layer (II) is supplied from the other side to be joined and laminated.

  In the coextrusion, the closed cell is better when the temperature of the resin melt 13 for forming the foam layer, the resin melt 9 for forming the resin layer (I), and the resin melt 10 for forming the resin layer (II) is as close as possible. From the viewpoint of obtaining a foam with a high rate and improving the surface smoothness of the foam.

  In the annular die 17, the resin melt 9 for forming the resin layer (I) and the resin melt 10 for forming the resin layer (II) are, for example, on the circumference of the annular die 17 as shown in FIGS. 7 and 8. The resin layer (I) forming resin melt 9 and the resin layer (II) forming resin melt are formed through the resin layer (I) forming and resin layer (II) forming channels X and Y. 10 can be laminated and laminated in a streak pattern on the outer peripheral surface of the foamed layer forming resin melt 13 from the resin layer (I) forming and resin layer (II) forming channel holes V1 and V2.

  The resin layer (I) 3 and the resin layer (I) are formed on the outer peripheral surface of the foamed layer 2 with respect to the resin layer (I) forming and resin layer (II) forming channel holes V1 and V2 processed in the annular die 17. II) The shape and the like are not particularly limited as long as 4 is formed. For example, the resin layer (I) of the annular die 17 and the grooves of the resin layer (II) forming flow path holes V1 and V2 shown in FIG. The width (a) is preferably 0.4 to 6.0 mm, more preferably 0.5 to 5.0 mm, and even more preferably 0.6 to 4.0 mm. The groove depth (b) of the channel hole is preferably 0.1 to 0.5 mm. By setting the width of the channel hole, the resin layer (I) 3 and the resin layer (II) 4 having a width of 0.5 to 20 mm, preferably 0.8 to 15 mm are formed on the surface of the foam layer 2. be able to. The width of the channel hole is not determined for each channel hole, and can be freely changed for each channel hole within the above range.

  In addition, the slanted channel hole as shown in FIG. 9 was used, and the resin melt for forming the resin layer (I) and the resin melt for forming the resin layer (II) were laminated on the foam layer and coextruded. Even in the case, the resin layer (I) and the resin layer (II) are continuously formed in the width direction. Further, since the resin melt for forming the resin layer (I) and the resin melt for forming the resin layer (II) are formed to be inclined, it becomes easy to form a pattern in which the streak pattern changes continuously. . Although not shown, a plurality of resin layer (II) forming channels Y are joined to the slit-shaped resin layer (I) forming channel X to form a resin layer (I) forming resin melt. After the resin melt for forming the resin layer (II) is laminated to form a laminated body in advance, a laminated foam as shown in FIG. 3 is formed by merging with the resin melt for forming the foam layer. You can also.

  In order to obtain the laminated foam 1 in which the resin layer (I) 3 and the resin layer (II) 4 in the above range are formed on the surface of the foam layer 2, for example, the blow-up ratio of the laminate foam 1 (the diameter of the mandrel is circular) The value can be adjusted by stretching the foam by controlling the discharge amount during extrusion foaming and the take-off speed.

  In addition, a plurality of resin melts 9 for forming the resin layer (I) and resin melts 10 for forming the resin layer (II) are joined and laminated in a line shape in the extrusion direction to the resin melt 13 for forming the foam layer. The cylindrical laminated foam coextruded from 17 can be cooled by passing the inner surface thereof onto a cylindrical cooling device (mandrel), and the cylindrical combined laminated foam can be cut open to form a sheet.

  Moreover, a plate-shaped laminated foamed plate can be obtained by sandwiching the cylindrical laminated foam with a pinch roll and joining the inner surfaces of the foamed layer 2 together.

(Total basis weight of resin layer)
The total basis weight of the resin layer (hereinafter sometimes referred to as the total lamination amount of the resin layer), that is, the total total basis weight of the resin layer (I) 3 and the resin layer (II) 4 is usually ^{2 to} 150 g / m ^2. , Preferably 4 to 100 g / m ² , more preferably 6 to 50 g / m ² . By setting the amount of lamination within the above range, it is possible to form a thin non-foamed resin layer. In addition, it can adjust to the said range so that the streak pattern by the resin layer (I) 3 and the resin layer (II) 4 may be exposed on the surface of the foam layer 2 in the extrusion direction.

  The total basis weight of the resin layer is, for example, an extruder discharge amount of the resin layer (I) 3 is L1 (kg / hr), and an extruder discharge amount of the resin layer (II) 4 is L2 (kg / hr). M (m / min) and foam full width N (m) can be obtained by the following equation (1).

Total basis weight of resin layer (g / m ² ) = (L1 + L2) × 10 ³ / (M × N × 60) (1)

  At this time, it is desirable that the discharge amount of L1 and L2 is based on the larger one, and the smaller one is −70% or less, preferably 50% or less. If it exceeds −70%, the maximum height of the contour curve on the surface of the foamed sheet may exceed 20 μm. Moreover, the width | variety of a streaky pattern can also be changed, maintaining the discharge amount of L1 and L2 so that L1 + L2 may always become constant, and the laminated foam 1 excellent in the design property can be obtained.

  In addition, in the polystyrene resin laminated foam of the present invention, the resin layer (III) can be formed on the outer surface of the resin layer (I) or the resin layer (II). For example, as a method of further laminating the resin layer (III) on the outer surface side, in addition to co-extrusion, a method of extruding and laminating as it is using an extruder after extrusion may be mentioned.

  Hereinafter, the polystyrene-based resin laminated foam of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples.

  As a production apparatus, as a first extruder for forming a foam layer 2, an extruder for forming a tandem foam layer comprising an extruder having a barrel inner diameter of 90 mm and an extruder having a barrel inner diameter of 120 mm connected to the downstream side of the extruder A co-extrusion annular die (lip diameter 67 mm, gap 0.6 mm) is attached to the outlet of the extruder, and a second extruder (inner diameter) for forming the resin layer (I) 3 is attached to the co-extrusion annular die. 65 mm) and a co-extrusion apparatus to which a third extruder for forming the resin layer (II) 4 (inner diameter 65 mm) was connected.

  Polystyrene resin for forming the foam layer shown in Table 1 and talc (parts by weight relative to the polystyrene resin) as the cell nucleating agent are supplied to the first extruder for forming the foam layer 2 and heated and kneaded. The amount of butane is injected as shown in the table, adjusted to a resin temperature suitable for foaming in the first extruder for forming the foam layer 2, and formed into a resin melt for forming the foam layer, and introduced into the co-extrusion annular die. did.

  Separately, a polystyrene resin for forming the resin layer (I) 3 shown in Table 1 and a brown inorganic pigment mainly composed of iron oxide are supplied to the second extruder for forming the resin layer (I) 3 and heated. After kneading, a volatile plasticizer was injected to obtain a resin melt for forming the resin layer (I) and introduced into a co-extrusion annular die.

  Further, a polystyrene resin for forming the resin layer (II) 4 shown in Table 1 is supplied to the third extruder, heated and kneaded, and then injected with a volatile plasticizer for forming the resin layer (II). The resin melt was introduced into a co-extrusion annular die.

  In an annular die for coextrusion, a resin melt for forming a foam layer, and a resin melt for forming a resin layer (I) having a streaky shape from an internal lip having a hole-like outlet having a rectangular cross section shown in FIG. The resin melt for forming the resin layer (II) is merged, laminated on the resin melt for forming the foam layer and then coextruded into a cylindrical shape, and then taken through a 270 mm ψ mandrel (blow-up ratio 4) and incised. A sheet-like foam of the present invention was obtained. The resin layer (I) and the resin layer (II) were laminated on one side of the foamed layer in a non-foamed state in a streak shape.

  In addition, Table 1 shows production conditions, physical properties of the foams, and the like in Examples and Comparative Examples.

In Table 1, the raw materials PS (1) to (3) used for the foam layer, the resin layer (I), and the resin layer (II) mean the following polystyrene resins.
PS (1): Polystyrene, 680 manufactured by PS Japan, melt viscosity 930 Pa · s
PS (2): polystyrene, GX154 manufactured by PS Japan, melt viscosity 1430 Pa · s
PS (3): polystyrene, 679 manufactured by PS Japan, melt viscosity 620 Pa · s

In addition, the melt viscosity of the polystyrene resin is based on JIS K 7199, using a flow property measuring machine of Capillograph 1D (manufactured by Toyo Seiki Seisakusho Co., Ltd.) under conditions of a temperature of 200 ° C. and a shear rate of 100 seconds− ¹ . It is a measured value.

Moreover, the following were used as a coloring agent and an antistatic agent.
Colorant (1) PS-M-SSCA11N7470BR manufactured by Dainichi Seika Kogyo Co., Ltd.
Colorant (2) SBF-T-3775 manufactured by Resino Color Industry Co., Ltd.
Antistatic agent (1) Entilla AS MK400 manufactured by Mitsui DuPont Polychemical Co., Ltd.

Example 1
[Example of blending volatile plasticizer with resin melt for resin layer formation]
According to the production conditions shown in Table 1, as the foam layer 2, a polystyrene resin as the resin layer (I) 3 is formed on the outer surface side of the resin melt for forming the foam layer formed by kneading the polystyrene resin (2) and the physical foaming agent. Resin melt for forming a resin layer (I) formed by kneading (1), a colorant (1) and a volatile plasticizer, and a polystyrene resin (1) and a volatile plasticizer as a resin layer (II) 4 And the resin melt for forming the resin layer (II) formed by kneading and laminating alternately and continuously in the width direction is laminated and coextruded to obtain a laminated foam.

  The colorant (1) was added as a master batch so that the amount of the colorant (1) added was 0.9 parts by weight with respect to 100 parts by weight of the polystyrene resin (1). In addition, the resin layer forming resin melt includes a plurality of resin layer (I) forming holes and resin layers (II) arranged on the outer circumferential edge of the flow path of the foamed layer forming resin melt in the annular die. Forming holes (resin layer (I) and resin layer (II) forming part Z in which flow path holes are alternately provided on both sides of the flow path surface) are joined and laminated at the V portion through the flow path. Extruded. In addition, the flow path hole used what arranged the V1 and V2 pattern shown in FIG. 7 as 1 unit, and arranged 22 units on the circumference. The properties of the obtained laminated foam are shown in Table 1.

(Example 2)
[Example of not adding volatile plasticizer to resin melt for resin layer formation]
According to the production conditions shown in Table 1, as the foam layer 2, a polystyrene resin as the resin layer (I) 3 is formed on the outer surface side of the resin melt for forming the foam layer formed by kneading the polystyrene resin (2) and the physical foaming agent. Resin melt for forming resin layer (I) formed by kneading (3) and colorant (1) and resin layer (II) formed by kneading polystyrene resin (3) as resin layer (II) 4 A laminated foam was obtained in the same manner as in Example 1 except that the resin melt was alternately merged and laminated continuously in the width direction and co-extruded.

(Example 3)
[Example of blending an antistatic agent without blending a volatile plasticizer with the resin layer forming resin melt]
According to the production conditions shown in Table 1, as the foam layer 2, a polystyrene resin as the resin layer (I) 3 is formed on the outer surface side of the resin melt for forming the foam layer formed by kneading the polystyrene resin (2) and the physical foaming agent. (3) Resin melt for forming resin layer (I) formed by kneading colorant (1) and antistatic agent (1), polystyrene resin (3) and antistatic agent as resin layer (II) 4 A resin foam for forming a resin layer (II) formed by kneading (1) was alternately and continuously joined and laminated in the width direction to obtain a laminated foam.

  The colorant (1) was added as a master batch so that the amount of the colorant (1) added was 0.9 parts by weight with respect to 100 parts by weight of the polystyrene resin (3), and the antistatic agent (1 ) Was added as a master batch so that the addition amount of the antistatic agent (1) was 10 parts by weight with respect to 100 parts by weight of the polystyrene resin (3). Further, the same annular die as that used in Example 1 was used.

Example 4
[Application Example of Example 2: Pattern Change / Example in which Coloring Agent is Blended in Foam Layer]
A large number of resin layer (I) formation holes and resin layer (II) formation holes (as shown in FIG. 8) are arranged on the circumferential outer edge of the flow path of the resin melt for forming the foam layer in the annular die. Similar to Example 2 except that the conditions in Table 1 were established through the flow path of part Z) in which 220 R1.8 mm flow path holes (b) were alternately provided on both sides of the road surface. A laminated foam was obtained.

  In addition, to the resin melt for forming the foam layer, the colorant (2) is added as a master batch, and the amount of the colorant (2) added is 0.5 parts by weight with respect to 100 parts by weight of the polystyrene resin (2). It added so that it might become. Table 1 shows the characteristics and the like of the obtained laminated foam. Similar to Example 2, a uniform streaky resin layer was formed as a whole, and the foam was a good foam with less surface irregularities.

(Example 5)
[Example of application of Example 4: Example of changing discharge amount of resin layer]
A laminated foam was obtained in the same manner as in Example 2 except that the discharge amounts of the second extruder and the third extruder were varied at a rate of change of 10% per minute in the range of + 50% to -50%. Table 1 shows the characteristics and the like of the obtained laminated foam. Corresponding to the change in the discharge amount, the width of the streaky pattern of the foam changed, but the surface irregularity was small, and the foam was a good foam closer to the grain. The discharge amount in the table is an average value per hour.

(Comparative Example 1)
A foam was obtained in the same manner as in Example 1 except that the resin layer (II) 4 was not provided.
When the maximum height of the contour curve on the surface of the foam exceeded 25 μm, it was not suitable for a printing sheet.

In Table 1, each characteristic was measured and evaluated as follows.

(Apparent density of foam)
The apparent density of the foam is the weight (g) of a test piece of 10 cm × 10 cm × (foam thickness) cut out from 5 randomly selected locations over the entire width of the foam from the outer dimensions of the test piece. The apparent density of each sample was determined by converting the value divided by the required volume (cm ³ ) into units (g / cm ³ ), and the average value of the obtained values was taken as the apparent density.

(Thickness of foam)
The thickness of the foam was determined as an arithmetic average value of thickness (mm) measured at 10 points at equal intervals from one end to the other end along the width direction of the foam.

(Foam basis weight)
The basis weight of the laminated foam 1 is such that a test piece having a width of 250 mm is cut out over the entire width of the laminated foam 1 and the weight (g) of the test piece is the area of the test piece (sheet width (mm) × 250 mm). split, in terms of weight (g) laminate foam 1 per 1 m ^2, was determined basis weight of the laminated foam 1 (g / ^{m 2)} this.

(The difference between the maximum and minimum foam basis weight for every 2 mm in width in 50 mm continuous in the width direction (TD direction))
The maximum and minimum difference in foam basis weight for every 2 mm in width in 50 mm continuous in the width direction (TD direction) of the foam is that the sample pieces cut in the width direction 50 mm and length 500 mm are cut into slits every 2 mm in width. The basis weight was calculated by measuring the weight of the width 2 mm and the length 500 mm, and the minimum value was subtracted from the maximum value.

(Maximum height of the contour curve on the foam surface)
The maximum height of the contour curve on the foam surface was measured using a surf coder SE1700α manufactured by Kosaka Laboratory Co., Ltd. in accordance with JIS B0601 (2001). In the width direction of the foam, cut out 5 pieces of 30 mm test pieces at equal intervals, place this test piece on a horizontal base, and bring the tip of the stylus with a tip curvature radius of 2 μm into contact with the sheet surface of the test piece Then, it was moved in the width direction at a moving speed of 0.5 mm / s, and the up and down variation of the stylus was sequentially measured. The measurement length specified by the moving distance of the test piece was set to be at least three times the cut-off value (8 mm). The arithmetic average value of the five measured values obtained was taken as the maximum height of the contour curve of the foam surface.

(Printability)
The printability is obtained by molding a foam using a 150 mm long x 150 mm wide mold having a depth twice the thickness of the foam, under the conditions that the foam thickness is twice that before molding. Printing is performed on the colored laminated resin surface of the molded product using an IGT Orange Pool Fa manufactured by IGT Testing Systems Co., Ltd. at a printing width of 50 mm, a printing speed of 0.3 m / sec, and a printing pressure of 200 N. It was evaluated with.
○: No print fading ×: Print fading is seen on the molded product

(Surface resistivity)
The surface resistivity of the foam surface was measured according to JIS K6271 (2001) after adjusting the state of the following test piece.
Test was performed by leaving a test piece cut into a size of 100 mm in length × 100 mm in width (thickness is the thickness of the foam) from the foamed sheet to be measured in an atmosphere of 30 ° C. and 30% relative humidity for 36 hours. After adjusting the state of the piece, the surface resistivity was determined under the condition of an applied voltage of 500 V in accordance with JIS K6271 (2001).

1 Polystyrene resin laminate foam (foam)
2 Polystyrene resin foam layer (foam layer)
3 Polystyrene resin layer (I) (colored resin layer)
4 Polystyrene colored resin layer (II) (resin layer)
DESCRIPTION OF SYMBOLS 5 Polystyrene resin which forms resin layer (I) 6 Polystyrene resin which forms resin layer (II) 7 Colorant 8 Volatile plasticizer 9 Resin melt for forming resin layer (I) 10 Resin layer (II) formation Resin melt for resin 11 Polystyrene resin for forming foam layer 12 Physical foaming agent 13 Resin melt for foam layer formation 14 First extruder 15 Second extruder 16 Third extruder 17 Annular die V Laminating part V1 Channel hole V2 Channel hole X Immediately before stacking Y Immediately after stacking Z Z-shaped part

Claims (4)

A polystyrene-based resin laminate foam in which a polystyrene-based resin layer is laminated by coextrusion on at least one surface of the polystyrene-based resin foam layer, and the polystyrene-based resin layer is formed in a plurality of stripes in the extrusion direction. The polystyrene resin layer is formed in a state where the resin layers adjacent to each other in the width direction are different in the width direction, and the apparent density of the polystyrene resin laminated foam is 0.04 to 0.21 g. / cm ³ and a polystyrene-based resin laminate foam total basis weight of the polystyrene resin layer is characterized in that it is a 2~100g / ^{m 2.} 2. The polystyrene type according to claim 1, wherein a thickness of the polystyrene resin laminated foam is 0.5 to 10 mm, and a basis weight of the polystyrene resin laminated foam is 70 to 600 g / m ^2. Resin laminated foam.   3. The polystyrene-based resin laminate foam according to claim 1, wherein the maximum height of the contour curve of the surface of the polystyrene-based resin layer of the polystyrene-based resin laminate foam is 20 μm or less. The plurality of polystyrene-based resin layers are formed of two kinds of resin layers formed in stripes in the extrusion direction, the resin layers are alternately and continuously formed in the width direction, and at least one resin layer has a colorant. The polystyrene-based resin laminated foam according to any one of claims 1 to 3, which is blended.