JP6754295B2 - Polystyrene resin plate-like laminated foam - Google Patents

Description

The present invention relates to a polystyrene-based resin plate-like laminated foam.

Conventionally, a plate-shaped polystyrene resin foam has been used as a material for display materials, packaging materials, food containers, etc. by utilizing the rigidity and light weight peculiar to the foam. Recently, in order to impart functionality such as rigidity improvement and antistatic, a polystyrene-based resin plate-like laminated foam in which a resin layer is laminated on a polystyrene-based resin foam layer has been studied (see Patent Document 1).

On the other hand, these polystyrene-based resin foam plates require physical properties such as cushioning (cushioning), impact resistance, and bending cracking resistance (not cracking when bent) in addition to rigidity and lightness depending on the application. May be done.

Co-extrusion laminated foam in which a polystyrene-based resin foam layer contains a styrene-based elastomer and a polyolefin-based resin layer is laminated on at least one side in order to improve mechanical properties such as impact resistance and cushioning properties of the polystyrene-based resin foam. A body has been proposed (see Patent Document 2).

Further, in order to improve the cushioning property of the polystyrene-based resin foam, a foamed sheet for thermoforming containing a mixture of polystyrene-based resin, low-density polyethylene and styrene-based thermoplastic elastomer as a main component has been proposed (Patent Documents). See 3).

JP-A-2005-14547 Japanese Unexamined Patent Publication No. 2006-297838 Japanese Unexamined Patent Publication No. 2003-183438

The coextruded laminated foam described in Patent Document 2 is considered to be used for thermoforming into a container or the like, and has a relatively large amount of styrene-based elastomer component contained in the foam layer, so that it has impact resistance. However, there are cases where higher rigidity is desired depending on the application, such as when used as a plate-shaped cushioning material.

In response to such a problem, the applicant comprises forming a polystyrene-based resin foam layer from a polystyrene-based resin composition containing a specific ratio of polystyrene-based resin, polyethylene-based resin, and styrene-based thermoplastic elastomer, and said the foamed layer. We have proposed a polystyrene-based resin plate-like laminated foam in which a thermoplastic resin layer containing a polyethylene-based resin composition is laminated and bonded by coextrusion on both sides of the above.

With the above configuration, the polystyrene-based resin foam layer and the thermoplastic resin layer resin layer containing the polyethylene-based resin composition can be adhered to each other, and the balance between impact resistance and rigidity and bending crack resistance are excellent. A plate-shaped laminated foam can be provided.

However, in the polystyrene-based resin plate-shaped laminated foam of the present proposal, for example, when the tape or the like is attached to the surface of the laminated foam and then the tape is peeled off, the foam layer and the thermoplastic resin layer may be peeled off. There was room for improvement in the adhesive strength between the foam layer and the thermoplastic resin layer. Further, in Patent Document 3, no consideration is given to the adhesive strength between the foam layer and the resin layer.

The present invention has been made in view of the above requirements, and is a polystyrene-based resin plate-like laminated foam having an excellent balance of physical properties of impact resistance and rigidity, and excellent adhesive strength between a foam layer and a resin layer and bending crack resistance. The challenge is to provide the body.

The present invention provides the polystyrene-based resin plate-like laminated foam described below.
<1> A polystyrene-based resin plate-like laminated foam having an overall apparent density of 0.03 to 0.3 g / cm ³ having a thermoplastic resin layer laminated and bonded on both sides of the polystyrene-based resin foam layer by coextrusion. ,
The foamed layer is composed of a polystyrene-based resin composition containing a polystyrene-based resin, a polyethylene-based resin, and a styrene-based thermoplastic elastomer, and the polystyrene-based resin composition is based on 100% by mass of the polystyrene-based resin composition. The content of the polystyrene-based resin in the product is 60 to 94% by mass, the content of the polyethylene-based resin is 5 to 30% by mass, the content of the styrene-based thermoplastic elastomer is 1 to 10% by mass, and the resin layer is It is composed of a thermoplastic resin composition containing a polyethylene resin and a polystyrene resin, and the content of the polyethylene resin in the thermoplastic resin composition is 100% by mass based on 100% by mass of the thermoplastic resin composition. A polystyrene-based resin plate-like laminated foam having a content of 20 to 65% by mass and a content of a polystyrene-based resin of 20 to 70% by mass.
<2> The content [mass%] of the polystyrene-based resin in the thermoplastic resin composition constituting the resin layer is the content [mass%] of the polystyrene-based resin in the polystyrene-based resin composition constituting the foamed layer. ], The polystyrene-based resin plate-like laminated foam according to <1>.
<3> The thermoplastic resin composition constituting the resin layer further contains a styrene-based thermoplastic elastomer, and the content of the styrene-based thermoplastic elastomer in the thermoplastic resin composition is the thermoplastic resin composition 100. The polystyrene-based resin plate-like laminated foam according to <1> or <2>, which is 1 to 10% by mass with respect to mass%.
<4> The polystyrene-based resin according to any one of <1> to <3>, wherein the polystyrene-based resin in the thermoplastic resin composition constituting the resin layer contains high-impact polystyrene (HIPS). Plate-like laminated foam.
<5> The polystyrene-based resin plate-like laminated foam according to any one of <1> to <4>, wherein the thermoplastic resin composition constituting the resin layer further contains a polymer-type antistatic agent. body.
<6> The polystyrene-based resin plate-like laminated foam according to any one of <1> to <5>, wherein the adhesive strength between the foam layer and the resin layer is 2N / 25 mm or more.

According to the polystyrene-based resin plate-like laminated foam of the present invention, the polystyrene-based resin foam layer has a thermoplastic resin layer containing a polyethylene-based resin laminated and bonded by coextrusion on both sides, and the foamed layer is a polystyrene-based resin. It is made of a resin composition containing a polyethylene resin and a styrene thermoplastic elastomer in a specific ratio, and the resin layer is made of a polystyrene resin in a specific ratio and a thermoplastic resin composition containing a polyethylene resin to withstand resistance. It is possible to provide a plate-shaped laminated foam having an excellent balance between impact resistance and rigidity, adhesive strength between a foam layer and a resin layer, and bending crack resistance. Further, by incorporating a specific ratio of polystyrene-based resin in the resin layer, it is possible to provide a polystyrene-based resin plate-like laminated foam having excellent slipperiness.

It is the schematic of the extruder used for manufacturing the polystyrene-based resin plate-like laminated foam of this invention.

The polystyrene-based resin plate-like laminated foam (hereinafter, also referred to as a foam) of the present invention is a thermoplastic resin layer laminated and bonded to both sides of a polystyrene-based resin foam layer (hereinafter, simply abbreviated as a foam layer) by coextrusion. A polystyrene-based resin plate-like laminated foam having (hereinafter, simply abbreviated as a resin layer), the foamed layer is a polystyrene-based resin composition containing a polystyrene-based resin, a polyethylene-based resin, and a styrene-based thermoplastic elastomer (hereinafter, simply abbreviated as a resin layer). Hereinafter, it is simply abbreviated as a polystyrene resin composition), and the resin layer is composed of a thermoplastic resin composition containing a polyethylene resin and a polystyrene resin (hereinafter, simply abbreviated as a thermoplastic resin composition). It was done.

[Effervescent layer]
(Polystyrene resin)
In the present invention, the polystyrene-based resin in the polystyrene-based resin composition constituting the foam layer is a polymer mainly composed of a styrene component, and is not only a styrene homopolymer but also a common weight of styrene and other monomers. Coalescence can be used. Specifically, polystyrene (GPPS), high-impact polystyrene (HIPS), styrene-acrylonitrile copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylate-methyl methacrylate copolymer. Combined, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl acrylate copolymer, styrene-maleic anhydride copolymer, polystyrene-polyphenylene ether copolymer, polystyrene and polyphenylene ether Examples include a mixture with and. Moreover, you may use these polystyrene-based resins in mixture of 2 or more types. Among these polystyrene-based resins, polystyrene (GPPS) is preferable because it is excellent in extrusion foamability.

The polystyrene resin in the present invention has a styrene component of 50 mol% or more, preferably 60 mol% or more, more preferably 80 mol% or more, and further preferably 90 mol% or more. Further, the polystyrene-based resin may contain a branched component such as divinylbenzene or a multi-branched polyfunctional macromonomer.

(Polyethylene resin)
The polyethylene-based resin in the polystyrene-based resin composition is a polymer mainly composed of an ethylene component, and is, for example, low-density polyethylene (LDPE), ultra-low-density polyethylene (VLDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene. Examples thereof include density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethyl ethylene-ethyl acrylate (EEA) and the like. Two or more kinds of these polyethylene-based resins may be mixed and used. Among these, low-density polyethylene (LDPE) is preferably used from the viewpoints of extrusion foamability during foam production, balance between impact resistance and rigidity of the foam, and cost efficiency.

When low-density polyethylene is used, the melt of low-density polyethylene measured based on JIS K 7210-1: 2014 (test temperature: 190 ° C., load 2.16 kg) from the viewpoint of extrusion foamability and physical property balance of the foam. The flow rate (MFR) is preferably 5 g / 10 min or less. The lower limit is approximately 0.1 g / 10 min or more.

In general, the low density polyethylene, refers to a density of 0.91 g / cm ³ or more 0.93 g / cm ³ less than the polyethylene-based resin having a long-chain branched structure. The polyethylene-based resin in the present invention has an ethylene component of 50 mol% or more, preferably 60 mol% or more, more preferably 80 mol% or more, and further preferably 90 mol% or more.

(Styrene-based thermoplastic elastomer)
As the styrene-based thermoplastic elastomer in the polystyrene-based resin composition, a known general styrene-based thermoplastic elastomer can be used. For example, styrene-ethylene-butylene-styrene block copolymer (hereinafter abbreviated as SEBS), styrene-butadiene-butylene-styrene block copolymer (hereinafter abbreviated as SBBS), styrene-butadiene-styrene block copolymer. Examples include coalescence (SBS), styrene-isoprene-styrene block copolymer (SIS), and the like. Among these, SEBS and SBBS can be preferably used from the viewpoint of adhesiveness to the resin layer and ease of use as a recycled raw material.

The above-mentioned styrene-based thermoplastic elastomer is described in detail in, for example, "Plastic Age", pp. 101-106 (June 1985). The ratio of the styrene component in the styrene-based thermoplastic elastomer is not particularly limited as long as the object and effect of the present invention can be achieved, but it is preferably about 20 to 50% by mass. More preferably, it is 25 to 45% by mass.

(Content of polyethylene resin in polystyrene resin composition)
The content of the polyethylene-based resin in the polystyrene-based resin composition is 5 to 30% by mass with the composition as 100% by mass. If the content of the polyethylene-based resin is too low, the adhesiveness between the foam layer and the resin layer may decrease, and the content of the styrene-based thermoplastic elastomer in the composition may be increased in order to ensure the impact resistance of the foam. Since it is necessary to increase the number, the rigidity of the foam tends to decrease, and the cost may increase.

Further, if the content of the polyethylene resin is too high, the appearance of the foam may be deteriorated, it may be difficult to maintain a high closed cell ratio of the foam layer, and the rigidity may be lowered.

From the above viewpoint, the lower limit of the content of the polyethylene resin is preferably 7% by mass, more preferably 10% by mass. On the other hand, the upper limit of the content is preferably 25% by mass or less, more preferably 20% by mass or less.

(Content of styrene-based thermoplastic elastomer in polystyrene-based resin composition)
The content of the styrene-based thermoplastic elastomer in the polystyrene-based resin composition is 1 to 10% by mass with the composition as 100% by mass. If the content of the styrene-based thermoplastic elastomer is too small, the impact resistance and bending crack resistance of the foam may decrease, and the dispersed state of the polyethylene-based resin in the polystyrene-based resin composition deteriorates, resulting in foaming. The surface condition of the body may deteriorate. Further, if the content of the styrene-based thermoplastic elastomer is too large, the rigidity of the foam tends to be lowered, and the cost may be increased.

From the above viewpoint, the lower limit of the content of the styrene-based thermoplastic elastomer is preferably 1.5% by mass, more preferably 2% by mass. On the other hand, the upper limit of the content is preferably 9% by mass, more preferably 8% by mass.

(Mass ratio of polyethylene resin and styrene thermoplastic elastomer)
The mass ratio of the polyethylene-based resin to the styrene-based thermoplastic elastomer in the polystyrene-based resin composition is preferably 100: 15 to 100: 80. By setting these mass ratios in the above range, it is possible to obtain a foam having better adhesiveness between the foam layer and the resin layer and having a better balance between rigidity, impact resistance and cost of the foam. ..

From the above viewpoint, the mass ratio of the polyethylene-based resin to the styrene-based thermoplastic elastomer is more preferably 100: 15 to 100: 70, and even more preferably 100: 15 to 100: 60.

(Content of polystyrene resin in polystyrene resin composition)
The content of the polystyrene-based resin in the polystyrene-based resin composition is 60 to 94% by mass with the composition as 100% by mass.

(Resin that can be blended in polystyrene-based resin composition)
The polystyrene-based resin composition constituting the foamed layer of the present invention may contain other resins other than the polystyrene-based resin and the polyethylene-based resin described above as long as the object of the present invention is not impaired. In that case, the blending amount of the other resin is preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 0% by mass with respect to 100% by mass of the polystyrene-based resin composition.

[Resin layer]
(Polyethylene resin)
The polyethylene-based resin in the thermoplastic resin composition constituting the resin layer is a polymer mainly composed of an ethylene component, and is, for example, low-density polyethylene (LDPE), ultra-low-density polyethylene (VLDPE), or linear low-density. Polyethylene (LLDPE), high density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethyl ethylene-ethyl acrylate (EEA), and two or more of these. A mixture can be used. Further, from the viewpoint of ease of use as a recycled raw material, it is preferable to use the same polyethylene-based resin as the foamed layer.

(Polystyrene resin)
The polystyrene-based resin in the thermoplastic resin composition constituting the resin layer is a polymer mainly composed of styrene. For example, not only a styrene homopolymer but also a copolymer of styrene and another monomer can be used. Can be used. Specifically, polystyrene (GPPS), high-impact polystyrene (HIPS), styrene-acrylonitrile copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylate-methyl methacrylate copolymer. Combined, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl acrylate copolymer, styrene-maleic anhydride copolymer, polystyrene-polyphenylene ether copolymer, polystyrene and polyphenylene ether Examples include a mixture with and. Moreover, you may use these polystyrene-based resins in mixture of 2 or more types.

In addition, these polystyrene-based resins have a styrene component of 50 mol% or more, preferably 60 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more. Further, the polystyrene-based resin may contain a branched component such as divinylbenzene or a multi-branched polyfunctional macromonomer.

Among these, polystyrene or high-impact polystyrene is preferably used, and particularly high-impact polystyrene can be preferably used, because the foam has excellent bending crack resistance. High-impact polystyrene is a polystyrene-based resin obtained by polymerizing styrene in the presence of rubber particles such as butanediene rubber. Styrene is grafted onto rubber to form a dispersed phase, and polystyrene forming a continuous phase. It is composed of and contains gel. Like other polystyrene-based resins, the high-impact polystyrene can contain other monomer components and branching agent components as copolymerization components in addition to styrene. From the viewpoint of bending crack resistance, the gel content in high-impact polystyrene is preferably 15% or more, and the upper limit thereof is preferably about 35%.

In the present invention, the adhesive strength between the foam layer and the resin layer is increased by laminating and adhering the above-mentioned polyethylene-based resin and polystyrene-based resin as resin layers on both sides of the foam layer by coextrusion. It can be improved, and further, the slipperiness of the surface of the foam can be improved.

(Styrene-based thermoplastic elastomer)
The thermoplastic resin composition constituting the resin layer preferably further contains a styrene-based thermoplastic elastomer. When the thermoplastic resin composition contains a styrene-based thermoplastic elastomer, the polyethylene-based resin and the polystyrene-based resin are more finely dispersed in the composition, and the bending crack resistance of the foam can be further improved. As the styrene-based thermoplastic elastomer, a known general styrene-based thermoplastic elastomer can be used. For example, styrene-ethylene-butylene-styrene block copolymer (hereinafter abbreviated as SEBS), styrene-butadiene-butylene-styrene block copolymer (hereinafter abbreviated as SBBS), styrene-butadiene-styrene block copolymer. Examples include coalescence (SBS), styrene-isoprene-styrene block copolymer (SIS), and the like. Among these, SEBS and SBBS can be preferably used from the viewpoint of adhesiveness to the foam layer and ease of use as a recycled raw material.

As for the above-mentioned styrene-based thermoplastic elastomer, it is preferable to use the same styrene-based thermoplastic elastomer as the foamed layer from the viewpoint of ease of use as a recycling raw material.

(Antistatic agent)
In the thermoplastic resin composition constituting the resin layer, in addition to the above components, it is preferable to add an antistatic agent capable of preventing dust and the like from adhering to the foam. As the antistatic material, a conventionally known material can be used, and in addition to a surfactant and the like, a block co-weight having a structure in which a block of polyolefin and a block of hydrophilic polymer such as polyether are repeatedly bonded, for example. A polymer-type antistatic agent such as coalescing can be used. Specifically, Perestat (trademark) VL300, Perestat HC250, Perectron (trademark) HS, Perectron PVH, etc. manufactured by Sanyo Chemical Industries, Ltd. can be exemplified.

(Content of polyethylene resin in thermoplastic resin composition)
The content of the polyethylene-based resin in the thermoplastic resin composition constituting the resin layer is 20 to 65% by mass, assuming that the thermoplastic resin composition is 100% by mass. When the content of the polyethylene-based resin is within the above range, the foam has a particularly excellent balance between bending and bending resistance and the adhesive force of the resin layer to the foam layer.

From the above viewpoint, the lower limit of the content of the polyethylene resin is preferably 30% by mass, more preferably 40% by mass. On the other hand, the upper limit of the content is preferably 60% by mass, more preferably 50% by mass.

(Content of polystyrene resin in thermoplastic resin composition)
The content of the polystyrene-based resin in the thermoplastic resin composition constituting the resin layer is 20 to 70% by mass, assuming that the thermoplastic resin composition is 100% by mass. If the content of the polystyrene-based resin is too low, the adhesive force between the foam layer and the resin layer may be insufficient. Further, if the content of the polystyrene resin is too high, the resin layer becomes brittle and may be easily cracked at the time of bending.

From the above viewpoint, the lower limit of the content of the polystyrene resin is preferably 25% by mass. On the other hand, the upper limit of the content is preferably 60% by mass, more preferably 50% by mass or less.
Further, from the viewpoint of achieving both impact resistance and bending and bending resistance of the foam at a high level, the content [mass%] of the polystyrene resin in the thermoplastic resin composition constituting the resin layer is foamed. It is preferably less than the content [mass%] of the polystyrene resin in the polystyrene resin composition constituting the layer.

(Content of styrene-based thermoplastic elastomer in thermoplastic resin composition)
When the styrene-based thermoplastic elastomer is blended in the thermoplastic resin composition constituting the resin layer, the content is preferably 1 to 10% by mass, more preferably 1 to 10% by mass, with the thermoplastic resin composition as 100% by mass. It is 2 to 8% by mass, more preferably 3 to 5% by mass.

(Content of high molecular weight antistatic agent in thermoplastic resin composition)
When the antistatic agent is blended in the thermoplastic resin composition constituting the resin layer, the content may be 20% by mass or less with respect to 100% by mass (including the antistatic agent) of the thermoplastic resin composition. It is preferably in the range of 5 to 15% by mass.

(Additive)
Further, additives can be added to the resin layer as long as the object of the present invention is not impaired. The type of additive is not particularly limited, but as a functional additive, a weather resistant agent, an ultraviolet absorber, a flame retardant, an inorganic filler, an antibacterial agent, a colorant and the like can be added.

[Polystyrene resin plate-like laminated foam]
The polystyrene-based resin plate-shaped laminated foam of the present invention is a polystyrene in which a resin layer composed of the thermoplastic resin composition is laminated and adhered to both sides of a foam layer composed of the polystyrene-based resin composition by coextrusion. It is a resin plate-like laminated foam. The details of the polystyrene-based resin plate-like laminated foam of the present invention will be described below.

(Overall apparent density)
The overall apparent density of the foam of the present invention is 0.03 to 0.3 g / cm ³ . If the overall apparent density is too low, it may be difficult to maintain the rigidity and strength of the foam. Further, if the overall apparent density is too high, it may be difficult to maintain the lightness of the foam.

From the above viewpoint, the upper limit of the total apparent density of the foam is preferably 0.2 g / cm ³ , and more preferably 0.1 g / cm ³ . On the other hand, the lower limit of the overall apparent density of the foam is preferably 0.04 g / cm ³ .

The overall apparent density of the foam in the present invention is determined as follows. First, a foam piece cut out from the foam with appropriate dimensions (for example, a foam piece obtained by cutting the polystyrene-based resin plate-shaped laminated foam over the entire width in the width direction with a length of 10 cm). By dividing the weight [g] of the test piece composed of the test piece by the area of the test piece (for example, 10 cm × the total width of the foam [cm]) and converting the unit, the basis weight of the foam [g / m ² ] Ask for. Then, the value obtained by dividing the basis weight of the foam by the total thickness [mm] of the foam is converted into a unit [g / cm ³ ] to obtain the total apparent density of the foam.

(Overall thickness)
The total thickness of the foam of the present invention is preferably 30 mm or less, more preferably 25 mm or less, still more preferably 20 mm or less, from the viewpoint of lightness and productivity of the foam. Further, the lower limit of the total thickness is preferably about 0.5 mm, more preferably 1 mm or more, still more preferably 2 mm or more, from the viewpoint of the rigidity of the foam.

The total thickness of the foam can be obtained as an arithmetic mean value of the thickness (mm) measured at 1 cm intervals in the width direction over the entire width of the polystyrene-based resin plate-shaped laminated foam.

(Closed cell ratio of foam layer)
The closed cell ratio of the foam layer is preferably 60% or more, more preferably 70% or more, still more preferably 80% or more, and particularly preferably 85% or more from the viewpoint of obtaining physical properties such as excellent rigidity and impact resistance. ..

The closed cell ratio: S (%) was measured using an air comparison hydrometer 930 type manufactured by Toshiba Beckman Co., Ltd. in accordance with procedure C described in ASTMD2856-70 (1976 recertification). The actual volume of the test piece (sum of the volume of the closed cell and the volume of the resin portion): Vx (cm ³ ) can be calculated by the following formula (1).
S (%) = (Vx-W / ρ) x 100 / (Va-W / ρ) ... (1)
However, Va, W, and ρ in the above formula are as follows.
Va: Apparent volume of the test piece used for measurement (cm ³ )
W: Weight of test piece (g)
ρ: Density of the resin composition constituting the test piece (g / cm ³ )

The density ρ (g / cm ³ ) of the resin composition is obtained by defoaming the air bubbles of the test piece used for the measurement and the weight W (g) of the test piece by a heating press and then cooling the test piece. It can be obtained from the volume of the sample (cm ³ ).

(Basis weight per side of resin layer)
The basis weight per side of the resin layer is preferably ³ to 50 g / m ² . By setting the basis weight per one side of the resin layer within the above range, the resin layer can be laminated more stably and uniformly, and a foam that is lightweight and has excellent impact resistance and bending crack resistance can be obtained. From the viewpoint of cost and lightness, the upper limit of the basis weight per one side of the foam is preferably 40 g / m ² , more preferably 30 g / m ² , and further preferably 20 g / m ² . ..

The basis weight per one side of the resin layer can be calculated from the basis weight of the foam by the following formula (2) based on the discharge amount of the entire foam during the production of the foam and the discharge amount per one side of the resin layer. it can.
Basis weight per one side of the resin layer [g / m ² ] = Basis weight of the foam [g / m ² ] × (Discharge amount per one side of the foam layer [kg / hr] / Discharge amount of the entire foam [kg] / Hr]) ・ ・ ・ (2)

When the foam layer and the resin layer can be separated, the basis weight of the separated resin layer can be obtained by converting the weight and area into the weight (g) per 1 m ² .

(Adhesive strength between foam layer and resin layer)
The adhesive strength between the foamed layer and the resin layer of the polystyrene-based resin plate-shaped laminated foam is preferably 2N / 25 mm or more, more preferably 3N / 25 mm or more, from the viewpoint of obtaining an excellent appearance (surface condition, surface smoothness). , More preferably 4N / 25mm or more.

Adhesive strength is specified as peeling adhesive strength measured based on the 90 ° peeling test described in JIS K6854-1: 1999. Specifically, first, the foam is cut out from the foam into dimensions of 250 mm in length and 25 mm in width along the extrusion direction and the width direction, and used as a test piece. Next, the resin layer is peeled off from the test piece in the extrusion direction (MD) and the width direction (TD) under the condition of a peeling speed of 50 mm / min, and the load at that time is measured as the adhesive strength. The arithmetic mean value of the measured value of MD and the measured value of TD is defined as the adhesive strength.

If the resin layer is easily broken and difficult to measure due to the small basis weight of the resin layer, etc., the surface side of the resin layer may be reinforced with tape or the like for measurement. Absent.

(Method for producing polystyrene-based resin plate-like laminated foam of the present invention)
Hereinafter, an embodiment of the method for producing a polystyrene-based resin plate-like laminated foam of the present invention will be described. FIG. 1 shows a schematic view of an extruder used for producing the polystyrene-based resin plate-shaped laminated foam of the present invention.

In the method for producing the foam 1 of the present invention, first, additives such as polystyrene-based resin 2, polyethylene-based resin 3, styrene-based elastomer 4, and other bubble modifiers added as needed are added to form the foam layer. 1 Supply to the extruder 5 and heat-knead, press-fit the foaming agent 6 and further knead the mixture, adjust the temperature to an appropriate foaming temperature, and obtain a resin melt 7 for forming a foam layer.

At the same time, the polyethylene-based resin 8 and the polystyrene-based resin 9 constituting the resin layer, the styrene-based elastomer 10 added as needed, the antistatic agent 11, the volatile plasticizer 13, various additives and the like are secondly added. It is supplied to the extruder 12 and kneaded by heating to adjust the temperature to an appropriate level to obtain a resin melt 14 for forming a resin layer.

The discharge amounts of the foam layer forming resin melt 7 and the resin layer forming resin melt 14 are controlled and introduced into the annular die 15. The foam layer forming resin melt 7 and the resin layer forming resin melt 14 are merged and laminated in the annular die 15, and then co-extruded to foam the foam layer forming resin on the outer peripheral surface of the foam layer. A tubular laminated foam in which a resin layer is laminated and adhered is produced. The present invention in which the resin layers are laminated and adhered to both sides of the foam layer by passing the tubular laminated foam through a pinch roll while taking it over and fusing the inner surfaces of the foam layers inside the tubular laminated foam. 1 of polystyrene-based resin plate-like laminated foam 1 can be obtained.

In coextrusion, it is preferable that the temperature of the resin melt 14 for forming the resin layer is as close as possible to the temperature of the resin melt 7 for forming the foam layer because a foam plate having a higher closed cell ratio can be obtained. Further, a tubular laminated foam in which resin layers are laminated and adhered to both the outer surface and the inner surface of the foam layer by coextrusion is produced, and the tubular laminated foam is placed along a mandrel which is a tubular cooling device. It is also possible to obtain a sheet-shaped laminated foam by cutting open and then flattening it in a heating furnace or the like to obtain the polystyrene-based resin plate-shaped laminated foam 1 of the present invention.

As various devices such as the annular die 15 and the extruder used for producing the polystyrene-based resin plate-shaped laminated foam 1, known devices conventionally used in the field of extrusion foaming can be appropriately used.

The proper foaming temperature of the resin melt 7 for forming a foam layer means a temperature at which the optimum viscoelasticity for foaming is exhibited. The appropriate foaming temperature is appropriately determined depending on the type and melt viscosity of the polystyrene resin 2, the type and the amount of the foaming agent 6, but is usually in the range of 130 ° C. or higher and 170 ° C. or lower.

(Bubble adjuster)
As the bubble adjusting agent added to the resin melt 7 for forming the foam layer, either an organic type or an inorganic type can be used. Examples of the inorganic bubble modifier include metal borate salts such as zinc borate, magnesium borate, and borax, sodium chloride, aluminum hydroxide, talc, zeolite, silica, calcium carbonate, and sodium bicarbonate. Examples of the organic bubble regulator include sodium 2,2-methylenebis (4,6-tert-butylphenyl) phosphate, sodium benzoate, calcium benzoate, aluminum benzoate, sodium stearate and the like. Further, a combination of citric acid and sodium bicarbonate, an alkali salt of citric acid and sodium bicarbonate and the like can also be used as a bubble regulator. Two or more of these bubble modifiers can be mixed and used.

The amount of the bubble adjusting agent added is approximately 0.05 to 10 parts by mass, preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the polymer component constituting the foam layer.

(Foaming agent)
Examples of the foaming agent 6 include aliphatic hydrocarbons having 2 to 6 carbon atoms such as propane, normal butane, isobutane, normal pentane, isopentan, isohexane, and cyclohexane, methyl chloride, ethyl chloride, 1,1,1,2. -Tetrafluoroethane, 1,1-difluoroethane and other halogenated aliphatic hydrocarbons with 1 to 3 carbon atoms, methanol, ethanol, propanol, butanol, isopropyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, etc. Aliphatic alcohols having 1 to 4 carbon atoms, or organic physical foaming agents such as methyl ethers, ethyl ethers, propyl ethers, isopropyl ethers, methyl ethyl ethers and other aliphatic ethers having 2 to 8 carbon atoms, nitrogen and dioxide. Examples thereof include inorganic physical foaming agents such as carbon and water.

The above-mentioned foaming agent 6 can be used by mixing two or more kinds. Among the above, the foaming agent 6 is preferably an organic physical foaming agent because it easily foams a polystyrene resin, and particularly preferably a normal butane, isobutane, or a mixture thereof as a main component.

When an organic physical foaming agent such as a butane mixture of 30% by mass of isobutane and 70% by mass of normal butane is used as the foaming agent 6, the amount of the foaming agent 6 added is 100 parts by mass of the polymer component constituting the foaming layer 6. It is approximately 0.5 to 10 parts by mass, preferably 1 to 8 parts by mass, and more preferably 2 to 6 parts by mass. As the foaming agent 6, a chemical foaming agent or the like can be used in combination in addition to the physical foaming agent.

(Volatile plasticizer)
In the method for producing a foam of the present invention, when the foam layer forming resin melt 7 and the resin layer forming resin melt 14 are co-extruded, the resin layer forming resin melt 14 at an appropriate foaming temperature is used. In order to improve the melt elongation of the resin layer and make the elongation of the resin melt 14 for forming the resin layer correspond to the elongation of the resin melt 7 for forming the foam layer, the volatile plasticizer 13 is added to the resin melt 14 for forming the resin layer. It is preferable to add it.

The volatile plasticizer 13 has a function of lowering the melt viscosity in the state of being present in the resin melt 14 for forming the resin layer, and after forming the resin layer, volatilizes from the resin layer and removes it from the resin layer. What is used is used.

Examples of the volatile plastic agent 13 include an aliphatic hydrocarbon having 2 to 6 carbon atoms, a halogenated aliphatic hydrocarbon having 1 to 3 carbon atoms, an aliphatic alcohol having 1 to 4 carbon atoms, or a carbon number of carbon atoms. One type selected from 2 or more and 8 or less aliphatic ethers or the like, or one composed of two or more types is preferably used, and among these, from the viewpoint of solubility in a thermoplastic resin composition, ease of handling, etc. Therefore, aliphatic hydrocarbons having 2 to 6 carbon atoms are preferable, and those containing normal butane, isobutane, or a mixture thereof as a main component are more preferable.

The amount of the volatile plasticizer 13 added is preferably about 1 to 10 parts by mass with respect to 100 parts by mass of the thermoplastic resin composition constituting the resin layer.

Hereinafter, the polystyrene-based resin plate-like laminated foam of the present invention will be specifically described with reference to Examples. However, the present invention is not limited to the examples.

As a manufacturing device, a ring for coextrusion is provided at the outlet of a tandem type foam layer forming extruder (first extruder) including an extruder having a barrel inner diameter of 90 mm and an extruder having a barrel inner diameter of 120 mm connected to the extruder. A coextrusion device was used in which a die (lip diameter 100 mm) was attached, and a resin layer forming extruder (second extruder) having a barrel inner diameter of 50 mm was connected to the coextrusion annular die.

The following materials were used for the foam layer and the resin layer to be introduced into the manufacturing apparatus.
[Effervescent layer]
Polystyrene resin (PS): Polystyrene GX154 manufactured by PS Japan Corporation
Polyethylene resin (PE): Sumitomo Chemical Co., Ltd. Low density polyethylene F102
Styrene-based Thermoplastic Elastomer (TPS): Asahi Kasei Co., Ltd. Styrene-ethylene-butylene-styrene block copolymer Tuftec H1041

[Resin layer]
Polyethylene resin (PE abbreviation A): Low-density polyethylene NUC8321 manufactured by Nippon Unicar Co., Ltd.
Polyethylene resin (PE abbreviation B): Linear low-density polyethylene manufactured by Japan Polyethylene Corporation Novatec LL UJ960
Antistatic agent (abbreviation C): Sanyo Kasei Co., Ltd. Polymer-type antistatic agent Polyolefin-polyolefin block copolymer Perectron HS
Styrene-based thermoplastic elastomer (TPS abbreviation D): Styrene-ethylene-butylene-styrene block copolymer (SEBS) manufactured by Asahi Kasei Co., Ltd. Tough Tech H1041
Polystyrene resin (PS abbreviation E): Polystyrene GX154 manufactured by PS Japan Corporation
Polystyrene resin (PS abbreviation F): Polystyrene HRM12 manufactured by Toyo Styrene Co., Ltd.
Polystyrene resin (PS abbreviation G): High impact polystyrene HT60 manufactured by PS Japan Corporation

Polystyrene resin GX154, polyethylene resin F102, and styrene thermoplastic elastomer H1041 for forming a foam layer were supplied to the first extruder so as to have the contents shown in Table 1, and the total content was 100 parts by mass. 1.0 part by mass of talc 35 mass% masterbatch was added as a bubble conditioner, heated and kneaded, and mixed butane (normal butane: isobutane = 70:30 (mass ratio)) as a foaming agent was 5.7 parts by mass. Was injected and further kneaded, and then adjusted to 136 ° C. to prepare a resin melt mixture for forming a foam layer, which was introduced into an annular die for coextrusion at a discharge rate of 96.8 kg / hr.

At the same time, Table 1 from polyethylene resins (A), (B), antistatic agents (C), styrene thermoplastic elastomers (D), polystyrene resins (E), (F), and (G) for forming the resin layer. Using the materials shown in (1), each compounding amount was supplied to the second extruder, heated and kneaded, and 4.5 parts by mass of mixed butane was injected into this as a volatile plastic agent and further kneaded, and then 160 The temperature was adjusted to a resin melt mixture for forming a resin layer, and the mixture was introduced into an annular die for coextrusion at a discharge rate of 9.4 kg / hr.

In the annular die for coextrusion, the resin melt mixture for forming a foam layer and the resin melt mixture for forming a resin layer are merged, and the resin melt mixture for forming a resin layer is laminated on the outer peripheral surface of the resin melt mixture for forming a foam layer. Was co-extruded into a tubular shape to form a tubular laminated foam. The tubular foam is taken up at a speed of 15.7 m / min, sandwiched between pinch rolls, and the inner surfaces thereof are fused to each other to fuse Examples 1 to 4 and Comparative Examples 1 to 6 having a width of 500 mm and a thickness of 5.0 mm. Was obtained from the polystyrene-based resin plate-like laminated foam.

With respect to the obtained polystyrene-based resin plate-like laminated foams of Examples 1 to 4 and Comparative Examples 1 to 6, the overall apparent density, thickness, basis weight, closed cell ratio of the foam layer, and tsubo per one side of the resin layer The amount and the adhesive strength between the foam layer and the resin layer were measured by the above-mentioned method. The results are shown in Table 1.

The basis weight per one side of the resin layer was determined by peeling the resin layer from the foam and dividing the mass of the resin layer by its area. The closed cell ratio of the foam layer was obtained by dividing the foam into five equal parts in the width direction, cutting out test pieces from the central portion in the width direction, and calculating the closed cell ratio of these test pieces as an arithmetic mean value.

Further, the flexural modulus of the obtained polystyrene-based resin plate-like laminated foams of Examples 1 to 4 and Comparative Examples 1 to 6 was measured under the following conditions, and the impact resistance, bending crack resistance, and surface were also measured. The condition (appearance) was evaluated according to the following criteria. The results are shown in Table 1.

(Flexural modulus)
The flexural modulus of the foam was measured in each of the extrusion direction (MD) and the width direction (TD) of the polystyrene-based resin plate-like laminated foam based on JIS K 7203-1982. A test piece (the thickness of the test piece is the same as that of the polystyrene resin plate-shaped laminated foam) is cut out from the polystyrene-based resin plate-shaped laminated foam to a size of 100 mm in length and 25 mm in width along the extrusion direction and the width direction. ).

Next, using the test piece, a measurement test of the flexural modulus was performed under the conditions of R = 5 mm at the tip of the fulcrum, R = 5 mm at the tip of the fulcrum, the distance between the fulcrums 50 mm, and the bending speed 10 mm / min. Measurements were performed on five test pieces in each of the extrusion direction and the width direction, and the obtained measured values of flexural modulus in the extrusion direction and arithmetic average values of the measured values of flexural modulus in the width direction were obtained, and the extrusion direction was obtained. The flexural modulus (MPa) in (MD) and the flexural modulus (MPa) in the width direction (TD) were taken.

(Impact resistance)
The impact resistance was evaluated based on the puncture impact strength.
The puncture impact strength was cut out from a polystyrene-based resin plate-like laminated foam in an environment of a temperature of 23 ° C. and a humidity of 50% in a dimension of length 120 mm × width 120 mm along the extrusion direction based on JIS P8134: 1998. It was measured using a test piece. Measurements were performed on five test pieces, and the arithmetic mean value of each measured value was defined as the puncture impact strength (N · cm) of the foam and evaluated according to the following criteria.
⊚: 150 N ・ cm or more ○: 100 N ・ cm or more and less than 150 N ・ cm ×: less than 100 N ・ cm

(Bending crack resistance)
The state of surface cracking when bent was evaluated by the following test method.
A test piece cut out from a polystyrene-based resin plate-shaped laminated foam in a size of 100 mm in length × 25 mm in width along the extrusion direction was bent at a speed of 100 mm / min by 90 ° or 180 ° around the lateral direction. Five test pieces were tested and visually evaluated according to the following criteria.
⊚: No cracks in the resin layer when all test pieces are bent 180 ° ○: No cracks in the resin layer when all test pieces are bent 90 °, but any test when bent up to 180 ° The resin layer is cracked by one piece ×: The resin layer is cracked by one of the test pieces when bent by 90 ° XX: The foam layer is also cracked by one of the test pieces when bent by 90 ° (surface condition) (appearance))
The surface condition (appearance) was visually evaluated according to the following criteria.
◯: No unevenness on the surface Δ: Some unevenness on the surface ×: Unevenness on the surface or pattern generation

From the results shown in Table 1, the polystyrene-based resin plate-shaped laminated foams having the configurations of Examples 1 to 4 according to the present invention have adhesive strength, flexural modulus, impact resistance, and bending crack resistance between the foam layer and the resin layer. Well-balanced and excellent results were obtained for all of the surface conditions (appearance).

On the other hand, in Comparative Examples 1 to 4 in which the polystyrene-based resin was not blended in the resin layer, the adhesive strength between the foam layer and the resin layer was inferior. In Comparative Example 5, in which the amount of the polystyrene-based resin blended into the resin layer was too small, the adhesive strength between the foam layer and the resin layer was inferior. Further, Comparative Example 6 in which the amount of the polystyrene resin blended in the resin layer was too large was inferior in impact resistance and bending crack resistance.

From these results, the polystyrene-based resin plate-shaped laminated foam of the present invention is a polystyrene-based resin plate-shaped laminated foam having an excellent balance of physical properties of impact resistance and rigidity, and excellent adhesive strength and bending crack resistance. Was confirmed.

1 Polystyrene-based resin Plate-like laminated foam 2 Polystyrene-based resin 3 Polystyrene-based resin 4 Styrene-based thermoplastic elastomer 5 First extruder 6 Foaming agent 7 Foam layer-forming resin melt 8 Polystyrene-based resin 9 Polystyrene-based resin 10 Styrene-based Polyplastic elastomer 11 Antistatic agent 12 Second extruder 13 Volatile plastic agent 14 Resin melt for forming resin layer 15 Cyclic die

Claims (6)

A polystyrene-based resin plate-like laminated foam having an overall apparent density of 0.03 to 0.3 g / cm ³ having a thermoplastic resin layer laminated and bonded on both sides of the polystyrene-based resin foam layer by coextrusion.
The foamed layer is composed of a polystyrene-based resin composition containing a polystyrene-based resin, a polyethylene-based resin, and a styrene-based thermoplastic elastomer, and the polystyrene-based resin composition is based on 100% by mass of the polystyrene-based resin composition. The content of the polystyrene-based resin in the product is 60 to 94% by mass, the content of the polyethylene-based resin is 5 to 30% by mass, the content of the styrene-based thermoplastic elastomer is 1 to 10% by mass, and the resin layer is It is composed of a thermoplastic resin composition containing a polyethylene resin and a polystyrene resin, and the content of the polyethylene resin in the thermoplastic resin composition is 100% by mass of the thermoplastic resin composition. A polystyrene-based resin plate-like laminated foam having a content of 20 to 65% by mass and a content of a polystyrene-based resin of 20 to 70% by mass. The content [mass%] of the polystyrene-based resin in the thermoplastic resin composition constituting the resin layer is larger than the content [mass%] of the polystyrene-based resin in the polystyrene-based resin composition constituting the foamed layer. The polystyrene-based resin plate-like laminated foam according to claim 1, wherein the amount is small. The thermoplastic resin composition constituting the resin layer further contains a styrene-based thermoplastic elastomer, and the content of the styrene-based thermoplastic elastomer in the thermoplastic resin composition is 100% by mass of the thermoplastic resin composition. The polystyrene-based resin plate-like laminated foam according to claim 1 or 2, wherein the content is 1 to 10% by mass. The polystyrene-based resin plate-like laminate according to any one of claims 1 to 3, wherein the polystyrene-based resin in the thermoplastic resin composition constituting the resin layer contains high-impact polystyrene (HIPS). Foam. The polystyrene-based resin plate-like laminated foam according to any one of claims 1 to 4, wherein the thermoplastic resin composition constituting the resin layer further contains a polymer-type antistatic agent. The polystyrene-based resin plate-like laminated foam according to any one of claims 1 to 5, wherein the adhesive strength between the foam layer and the resin layer is 2N / 25 mm or more.

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