JP6177058B2 - Laminated sheet and container using the same - Google Patents

Description

The present invention relates to a laminated sheet and a container using the same.

Sheets or films mainly composed of a vinyl aromatic hydrocarbon polymer such as polystyrene are excellent in transparency and moldability, so that various packaging materials such as industrial containers including food containers, beverage containers, and various trays have been conventionally used. Widely used in applications. Polystyrene is poor in impact resistance and folding resistance, and when used as a simple substance, the sheet is liable to break and roll processing is difficult. Patent Documents 1 and 2 describe that high impact polystyrene is mixed and used. However, even if polystyrene and high impact polystyrene are mixed, there is a problem that the reinforcing effect is poor and the practical strength is low. Moreover, development of the sheet | seat which can contain a higher ratio of polystyrene was desired from the point of cost.
Furthermore, the sheet is also used as a packaging material for semiconductors and electronic parts, especially integrated circuits (IC) and electronic parts using ICs (Patent Documents 3 and 4), but is used for embossed carrier tapes and the like. In this case, there is a problem that burrs are generated in the cross section when the raw sheet is slit or when a sprocket hole is punched by embossing.

JP 2003-055526 A JP 2005-23268 A JP-A-9-174769 JP 2002-292805 A

In view of the above problems and circumstances, an object of the present invention is to provide a laminated sheet excellent in impact resistance, folding resistance, and burr suppression. Furthermore, it aims at providing the container with favorable moldability using this laminated sheet.

The present invention for solving the above-described problems is constituted as follows.
(1) A layer formed by alternately laminating (A) A layer containing vinyl aromatic hydrocarbon polymer and (B) B layer containing copolymer of vinyl aromatic hydrocarbon and conjugated diene The average thickness per layer of the A layer is 1.5 μm or more and 7 μm or less, and the ratio of the average thickness per layer of the B layer to the average thickness per layer of the A layer (1 of the B layer (Average thickness per layer / average thickness per A layer) is 0.45 or more and 4 or less, and a laminated sheet in which B layers are arranged on both surface layers.
(2) The laminated sheet according to (1), wherein the total number of layers is from 21 to 1001, and the total thickness is from 0.1 mm to 1.5 mm.
(3) The laminated sheet according to (1) or (2), wherein the (A) vinyl aromatic hydrocarbon polymer is polystyrene having a melt mass flow rate of 2 g / 10 min to 30 g / 10 min.
(4) (B) The vinyl aromatic hydrocarbon content in the copolymer of vinyl aromatic hydrocarbon and conjugated diene is 30 to 95 parts by mass, according to any one of (1) to (3) Laminated sheet.
(5) (B) The copolymer of vinyl aromatic hydrocarbon and conjugated diene is selected from a polybutadiene / polystyrene graft copolymer, a polystyrene / polybutadiene block copolymer, and a polystyrene / polyisoprene block copolymer. The laminated sheet according to any one of (1) to (4), which is at least one kind.
(6) A container formed using the laminated sheet according to any one of (1) to (5).
(7) The container according to (6), wherein the container is a carrier tape.

In the present invention, (A) A layer containing vinyl aromatic hydrocarbon polymer and (B) B layer containing vinyl aromatic hydrocarbon and conjugated diene copolymer are alternately laminated. In the laminated sheet, the average thickness per one layer of the A layer, the average thickness per one layer of the A layer, and the average thickness per one layer of the B layer are in a specific range, and the B layer is arranged on both surfaces. As a result, it has been found that impact resistance, fold resistance, and burr suppression are remarkably improved. Moreover, containers, such as a carrier tape excellent in the moldability, can be obtained by using the laminated sheet of the present invention. In addition, folding resistance represents the characteristic of maintaining the original shape without deformation of the container when a stress is applied to the container formed using the laminated sheet of the present invention.

In the laminated sheet of the present invention, (A) A layer containing a vinyl aromatic hydrocarbon polymer and (B) B layer containing a vinyl aromatic hydrocarbon / conjugated diene copolymer are alternately laminated. Form the structure.

The average thickness per one layer of A layer is 1.5 micrometers or more and 7 micrometers or less, and it is more preferable that they are 3 micrometers or more and 6 micrometers or less. If the average thickness of the A layer per layer is less than 1.5 μm, the formability of the laminated sheet may deteriorate. On the other hand, if it exceeds 7 μm, impact resistance and folding resistance may be lowered. In addition, the thickness per layer of the A layer and the B layer can be measured by microscopic observation after cutting out a section of the laminated sheet and smoothing the end face.

The ratio of the average thickness per B layer to the average thickness per A layer (average thickness per B layer / average thickness per A layer) is 0.45 or more and 4 or less. It is more preferable that it is 0.67 or more and 3.0 or less. If it is less than 0.45, impact resistance and folding resistance may be lowered. On the other hand, if it exceeds 4, the rate of occurrence of burrs and the moldability of the container may decrease.

In the laminated sheet, both outermost surfaces are B layers. By making the B layer the outermost surface, it is possible to suppress the growth of cracks generated on the outermost surface when the sheet is punched out, so that the impact resistance and the folding resistance are improved.

The number of layers in the laminated sheet of the present invention is preferably 21 or more and 1001 or less, and more preferably 41 or more and 121 or less. If it is less than 21 layers, impact resistance and folding resistance may be lowered. On the other hand, if it exceeds 1001 layers, layer uniformity cannot be obtained, and the formability of the laminated sheet may deteriorate.

The total thickness of the laminated sheet is preferably 0.1 mm or more and less than 1.5 mm, and more preferably 0.2 mm or more and 1.0 mm or less. If the thickness is less than 0.1 mm, the thickness after molding may become thin when molded into a container, and the rigidity of the molded product may be insufficient. Moreover, when it exceeds 1.5 mm, the moldability of a laminated sheet will fall and the yield of a sheet | seat may fall.

As the vinyl aromatic hydrocarbon polymer forming the A layer, styrene, alkyl-substituted styrene (for example, vinyltoluene, vinylxylene, p-ethylstyrene, p-isopropylstyrene, butylstyrene, pt-butylstyrene, etc.) And a resin obtained by polymerizing monomers such as halogen-substituted styrene (for example, chlorostyrene, bromostyrene and the like) and α-alkyl-substituted styrene (for example, α-methylstyrene and the like) substituted with an alkyl group at the α-position. These vinyl hydrocarbon monomers can be used as a homopolymer or a copolymer of two or more kinds of vinyl hydrocarbon monomers. Among these monomers, resins obtained by polymerizing styrene, vinyltoluene, α-methylstyrene and the like are preferable, and polystyrene which is a polymer of styrene is particularly preferable.

As polystyrene, it is preferable that the melt mass flow rate measured under 200 degreeC and a 5 kgf load according to JISK7210 is 2 g / 10min or more and 30 g / 10min or less. If the melt mass flow rate is less than 2 g / 10 min or exceeds 30 g / 10 min, the moldability of the laminated sheet may be lowered.

The vinyl aromatic hydrocarbon polymer forming the A layer may be copolymerized with acrylonitrile, methyl methacrylate, maleic anhydride or the like within a range not impairing practical physical properties.

The copolymer of vinyl aromatic hydrocarbon and conjugated diene forming the B layer includes a random copolymer of polybutadiene and polystyrene such as SBR rubber, a graft copolymer of polybutadiene and polystyrene such as high impact polystyrene, and an SB block polymer. And a block copolymer of polystyrene and polybutadiene such as SBS block polymer, a block copolymer of polystyrene and polyisoprene such as SI block polymer and SIS block polymer, and hydrogenated resins thereof. Among these, high impact polystyrene, SB block polymer and SI block polymer are preferable, and SB block polymer is particularly preferable.

The vinyl aromatic hydrocarbon content in the copolymer of vinyl aromatic hydrocarbon and conjugated diene is preferably 30 to 95 parts by mass, and more preferably 40 to 91 parts by mass. If the vinyl aromatic hydrocarbon is less than 30 parts by mass, the moldability of the container is lowered, and if it exceeds 95 parts by mass, the impact resistance and folding resistance may be lowered.

The layer B has an acrylonitrile-butadiene copolymer, an acrylonitrile-butadiene-styrene copolymer (ABS resin), a methyl methacrylate-butadiene-styrene copolymer (MBS resin), methyl, as long as practical properties are not impaired. A methacrylate-butyl acrylate-butadiene-styrene copolymer or the like can also be added.

The laminated sheet of the present invention is a B layer in which both surface layers contain a copolymer of vinyl aromatic hydrocarbon and conjugated diene. In the case where the surface layer is an A layer containing a vinyl hydrocarbon polymer as a water component, cracks are likely to occur starting from the A layer, and impact resistance and fold resistance may be reduced.

A method for producing the laminated sheet of the present invention will be described. Basically, a resin forming a multilayer structure is supplied to an extruder, melted and kneaded, supplied to a feed block and laminated, and a laminated sheet is extruded. For example, as described in Japanese Patent Application Laid-Open No. 2007-307893, resin is supplied from two extruders, and molten resin from each flow path is mixed with a multi-manifold type feed block that is a known laminating apparatus and a square. By using a mixer or using only comb-type feed blocks, it can be multi-layered to 9 layers or more. The square mixer is a known cylinder having a joining section that divides a polymer flow path into two with a square cross-sectional area and further joins the branched polymers so that they are stacked again in the thickness direction. Is the body.

In the method for producing a laminated sheet in which both surface layers of the present invention are B layers, a multilayer sheet is formed by the above-described method, and then the A layer of the multilayer sheet is the outermost surface using a multi-layer manifold die for two layers. In addition, there is a method of further laminating one B layer.

As a preferable method for producing the multilayer sheet of the present invention, it is preferable that the sheet can be continuously produced in a laminated sheet film forming apparatus.

In the laminated sheet of the present invention, the 50% fracture height of the DuPont impact strength defined by ASTM D2794 preferably has an impact resistance of 0.15 J or more, and more preferably 0.25 J or more. If it is less than 0.15 J, the impact resistance is poor, so the container may be damaged when the container is molded.

The laminated sheet of the present invention preferably has a bending strength of 10 times or more, more preferably 200 times or more, in a folding resistance test specified by JIS P8115. If it is less than 10 times, the folding resistance is too low and the molded container may be damaged.

The preferable range of the burr generation rate of the laminated sheet of the present invention is less than 6%, and more preferably less than 4%. If it is 6% or more, burr may cause a mounting trouble.

A preferable form of the container formability of the laminated sheet of the present invention is that the formability of the container pocket is continuously expressed. If the moldability of the container pocket is not continuously expressed, it may be difficult to use as a container.

The laminated sheet of the present invention can be formed into various containers by known thermoforming methods such as vacuum forming, pressure forming, vacuum / pressure forming, press forming, hot plate forming, and the like. The container using the laminated sheet of the present invention can be suitably used for various containers such as food containers, beverage containers, pharmaceutical containers, daily necessities containers, and carrier tapes.

EXAMPLES Hereinafter, although an Example demonstrates this invention, these Examples do not limit this invention.

[Example 1]
In order to form a plurality of layers, a laminated sheet was formed by the following method using a laminated sheet film forming apparatus equipped with a feed block and a square mixer and a T die.
As the A layer, polystyrene having a melt mass flow rate of 8.5 g / 10 min (Toyo Styrol (registered trademark) G200C, manufactured by Toyo Styrene Co., Ltd.) was melt-extruded at 220 ° C. with a φ40 mm single screw extruder, and as the B layer, A SB block copolymer having a polystyrene content of 75 parts by mass (manufactured by Denki Kagaku Kogyo Co., Ltd., Clearen 730L) was melt-extruded at 220 ° C. with a single screw extruder of φ40 mm. After these molten resins are merged and laminated using a feed block, the B layer is laminated on the outermost layer on the A layer side using a multi-layer die for two layers, and cooled and solidified with a roll adjusted to 80 ° C. A 61-layer laminated sheet was formed. The ratio of the total thickness of the A layer to the average thickness of the B layer per layer was set to be 1: 1.
The average thickness per layer of the A layer and the B layer measured by microscopic observation is 5.07 μm and 4.77 μm, respectively, and the average thickness per one layer of the B layer with respect to the average thickness per one layer of the A layer The ratio was 0.94. The results are shown in Table 1.

  Evaluation of the obtained laminated sheet followed the following method.

<Average thickness per A layer and B layer>
The average thickness per one layer of A layer and B layer in the obtained lamination sheet was calculated | required as follows. First, three 20 mm square pieces were cut out from an arbitrary position orthogonal to the production direction of the laminated sheet. After smoothing the end face, the thickness of any 10 layers of layer A per slice was measured with a Keyence microscope (model: VK-X100). The same measurement was performed for the remaining two slices, and the arithmetic average value was defined as the average thickness per layer of the A layer. Moreover, the average thickness per B layer was calculated | required by the same method.

<Total thickness of laminated sheet>
The thickness of the laminated sheet was measured using a micrometer.

<Formability of sheet>
By visually observing the appearance of the laminated sheet, the formability of the sheet was evaluated by the following determination.
Good: No whitening phenomenon such as melt fracture or delamination occurred on the surface of the molded sheet.
Possible: A whitening phenomenon such as melt fracture or delamination occurs partially on the surface of the molded sheet.
Defect: A whitening phenomenon such as melt fracture or delamination occurs on the entire surface of the molded sheet.

<Formability of carrier tape>
The laminated sheet was slit to a width of 24 mm, and 6 containers with an opening of 10 mm × 15 mm and a depth of 0.5 mm were formed at a mold temperature of 200 ° C. using a pressure-air molding machine (model: 2.1) manufactured by EDG. The moldability was evaluated visually. The moldability was evaluated according to the following judgment.
Good: A good container pocket shape was obtained for all molded products.
Possible: A part of the molded product in which a container pocket-shaped defect or hole was observed.
Defective: All of the molded products were observed to have a container pocket shape defect or hole.

<DuPont impact strength>
Using a DuPont impact tester (manufactured by Toyo Seiki Co., Ltd., B-351000601), using a striker with a tip radius of 7.9 mm, measurement was performed in an environment of 23 ° C. and 50% relative humidity according to ASTM D2794. The measured value was determined according to the following criteria.
Good: DuPont impact strength is 0.25 J or more.
Good: DuPont impact strength is 0.15 J or more and less than 0.25 J.
Defect: DuPont impact is less than 0.15J.

<Folding strength>
Folding strength is MIT-D Folding Fatigue Tester (C) manufactured by Toyo Seiki Co., Ltd. for each of the sheet production direction (hereinafter abbreviated as MD) and the direction orthogonal to the production direction (hereinafter abbreviated as TD). -111001405) in accordance with JIS-P8115 and measured in an environment of 23 ° C. and 50% relative humidity. The measured value was determined according to the following criteria.
Good: Folding strength in both MD and TD directions is 200 times or more.
Possible: The bending strength of at least one of the MD direction and the TD direction is less than 200 times and 10 times or more.
Defect: Both folding strengths in the MD direction and TD direction are less than 10 times.

<Burr generation rate>
The laminated sheets formed in each example and comparative example were formed with a vacuum rotary type embossed carrier tape forming machine (CTF-200, manufactured by CKD), and punching of individual sprocket holes of the embossed carrier tape was performed in the forming process. Punching was performed under the conditions of a pin-to-die clearance on one side of 20 μm and a punching speed of 250 mm / sec.
Next, the sprocket hole was photographed with a measuring microscope (MF-A, manufactured by Mitutoyo) at a magnification of 30 times, and the image (number of pixels 640 × 480) was read into image processing software (Photoshop, manufactured by Adobe). Binarization (black and white image) The area ratio was calculated from the number of pixels of a perfect circle having a specified hole diameter where no burr was generated and the number of pixels of the punched hole portion of each sample, and the ratio of the burr covering the punched hole was obtained. The burr generation rate was determined according to the following judgment.
Good: Burr generation rate is less than 4%.
Possible: Burr generation rate is 4% or more and less than 6%.
Defect: The burr occurrence rate is 6% or more.

[Example 2]
A laminated sheet is formed in the same manner as in Example 1 except that the resin of layer B is changed to high impact polystyrene (Toyo Styrol (registered trademark) H850N, manufactured by Toyo Styrene Co., Ltd.) having a polystyrene content of 91 parts by mass. did. The results are shown in Table 1.

[Example 3]
A laminated sheet is formed in the same manner as in Example 1 except that the resin of layer B is changed to an SI block copolymer (Asaprene (registered trademark) 670A manufactured by Asahi Kasei Co., Ltd.) having a polystyrene content of 40 parts by mass. did. The results are shown in Table 1.

[Examples 4 to 9]
The ratio of the average thickness per layer of the A layer and the B layer, the total number of layers, and the average thickness per layer of the B layer to the average thickness per layer of the A layer were changed to the values shown in Table 1. Except for the above, a laminated sheet was formed in the same manner as in Example 1. The results are shown in Table 1.

[Example 10]
A laminated sheet was formed in the same manner as in Example 1 except that the resin of the A layer was changed to polystyrene (Toyostyrene (registered trademark) G100C, manufactured by Toyo Styrene Co., Ltd.) having a melt mass flow rate of 26 g / 10 min. The results are shown in Table 1.

[Example 11]
A laminated sheet is formed in the same manner as in Example 1 except that the resin of layer A is changed to polystyrene (Toyo Styrol (registered trademark) HRM18, manufactured by Toyo Styrene Co., Ltd.) having a melt mass flow rate of 5.0 g / 10 min. did. The results are shown in Table 1.

[Comparative Example 1]
Using the polystyrene used in Example 1 for the A layer and the SB block copolymer used in Example 1 for the B layer, the average thickness per layer of the B layer and the average per layer of the A layer A total of 61 laminated sheets having a thickness ratio of 0.36 were produced. The resulting laminated sheets had low Dupont impact strength and bending strength. The results are shown in Table 2.

[Comparative Example 2]
The polystyrene used in layer A of Example 1 was used, and a single-layer sheet made of only polystyrene having a sheet thickness of 0.3 mm was formed at 220 ° C. with a φ40 mm single-screw extruder. As a result, a good sheet could not be obtained.

[Comparative Example 3]
The polystyrene used in the A layer of Example 1 and the SB block copolymer used in the B layer of Example 1 were mixed at a mass ratio of 6 to 4, and this was mixed at 220 ° C. with a φ40 mm single screw extruder. A single-layer sheet having a sheet thickness of 0.3 mm was formed, but the DuPont impact strength was low and the burr generation rate was high.

[Comparative Example 4]
Under the same conditions as in Example 1, a laminated sheet having an average thickness of 7.06 μm per A layer was produced, but the DuPont impact strength and folding strength were low.

[Comparative Example 5]
Under the same conditions as in Example 1, a laminated sheet having an average thickness of 0.97 μm per A layer was produced, but the burr generation rate was high.

  Under the same conditions as in Example 1, a laminated sheet having an average thickness of 4.78 for the B layer relative to the average thickness of the A layer for each layer was produced. The result was inferior.

[Comparative Example 7]
The sheet was molded using the block copolymer of styrene and butadiene used in the B layer of Example 1 for the A layer, and the polystyrene used in the A layer of Example 1 for the B layer. As a result, a good sheet could not be obtained.

  From the results in Tables 1 and 2, it can be seen that the laminated sheet of the present invention is excellent in impact resistance, fold resistance, and burr suppression even if the vinyl aromatic hydrocarbon polymer is high in content. Moreover, it turns out that the carrier tape using this laminated sheet is excellent in moldability.

  The laminated sheet of the present invention is excellent in impact resistance, fold resistance, molding processability, and excellent in burr suppression, so that it is suitably used as a carrier tape, food container, beverage container, pharmaceutical container, It can be used for various purposes such as daily necessities containers.

Claims (7)

(A) A layer containing a vinyl aromatic hydrocarbon polymer;
(B) B layer containing a copolymer of vinyl aromatic hydrocarbon and conjugated diene;
Are laminated sheets that are alternately laminated,
The average thickness per layer of the A layer is 1.5 μm or more and 7 μm or less,
The ratio of the average thickness per layer of B layer to the average thickness per layer of A layer (average thickness per B layer / average thickness per A layer) is 0.45 or more and 4 or less Yes,
And the lamination sheet by which B layer was arrange | positioned at both surface layers. The laminated sheet according to claim 1, wherein the total number of layers is 21 or more and 1001 or less and the total thickness is 0.1 to 1.5 mm. (A) The laminated sheet according to claim 1 or 2, wherein the vinyl aromatic hydrocarbon polymer is polystyrene having a melt mass flow rate of 2 g / 10 min to 30 g / 10 min. (B) The laminated sheet according to any one of claims 1 to 3, wherein the vinyl aromatic hydrocarbon content in the copolymer of vinyl aromatic hydrocarbon and conjugated diene is 30 to 95 parts by mass. (B) at least the copolymer of vinyl aromatic hydrocarbon and conjugated diene is selected from a graft copolymer of polybutadiene and polystyrene, a block copolymer of polystyrene and polybutadiene, and a block copolymer of polystyrene and polyisoprene. The laminated sheet according to any one of claims 1 to 4, which is one or more types. The container shape | molded using the laminated sheet as described in any one of Claims 1-5. The container according to claim 6, wherein the container is a carrier tape.