JPH09262920A - Hard polyvinyl chloride resin type multilayered sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance lightweight properties, rigidity, impact resistance or the like and to reduce the direction dependence of physical properties by integrally laminating a non-foamed surface layer composed of a polyvinyl chloride resin compsn. containing an impact resistance modifier to a foam core layer composed of a polyvinyl chloride resin compsn. containing a foaming agent and a flow characteristic modifier. SOLUTION: This hard polyvinyl chloride resin type multilayered sheet consists of a foam core layer composed of a polyvinyl chloride resin compsn. containing a foaming agent and a flow characteristic modifier and a non-foamed surface layer composed of a polyvinyl chloride resin compsn. containing an impact resistance modifier integrally laminated to the single surface or both surfaces of the foam core layer. That is, the polyvinyl chloride resin compsn. containing the foaming agent and the flow characteristic modifier and forming the foam core layer at a time of extrusion molding is melted and kneaded while the polyvinyl chloride resin compsn. containing the impact resistance modifier and forming the non-foamed surface layer at a time of extrusion molding is melted and kneaded and the latter resin compsn. is laminated to the single surface or both surfaces of the former resin compsn. to perform co- extrusion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as a material for various molded products and a material for industrial products in the fields of mining, civil engineering, agriculture, fisheries, daily necessities, etc., and as a material for outdoor signs, outdoor ducts, etc. The present invention relates to a rigid polyvinyl chloride resin-based multilayer sheet and a method for producing the same.

[0002]

2. Description of the Related Art In applications such as outdoor signboards, outdoor ducts, and indoor store clothing, lightweight polyvinyl chloride resins are generally used because they are required to be lightweight.

[0003]

However, the low-foaming hard polyvinyl chloride resin is inferior in rigidity, impact resistance, and heat distortion resistance, and has a difference in physical properties in the flow direction and the width direction after extrusion molding. The problem is that it is very large. Furthermore, since there is no surface layer, there are problems that the surface smoothness is poor, the appearance is poor, and stains easily occur.

On the other hand, when a low-foaming hard polyvinyl chloride resin sheet is extrusion-molded, the resin pressure rises due to the decomposition of the foaming agent, which increases the load on the extruder. This tendency is particularly remarkable when a modifier (acrylic type, methacrylic acid ester-butadiene-styrene copolymer type, etc.) is blended in order to impart impact resistance. Also, due to the increase in resin pressure and the increase in resin heat generation due to the blending of the impact resistance modifier, it becomes difficult to control foaming, resulting in excessive foaming and residual foaming agent, resulting in very poor appearance and production processability. .
When laminating and extruding, since the foam layer contacts the resin surface instead of the metal surface in the flow path, the shear stress at the resin interface is large, and it is more difficult to control foaming.

The present invention has been made in view of the above technical background, and is lightweight, excellent in rigidity, impact resistance, heat distortion resistance and production workability, and has little directional dependence of physical properties, and It is an object of the present invention to provide a rigid polyvinyl chloride resin sheet and a method for producing the same, which imposes less load on the extruder during extrusion molding.

[0006]

In order to achieve the above object, the inventors of the present invention have conducted earnest research and as a result, as a result of improving the fluidity of the foam layer, a surface layer having impact resistance is used together with the foam layer. It has been found that by extruding, the rigidity, impact resistance, heat distortion resistance, production processability and appearance are excellent, and the direction dependence of physical properties can be reduced.

That is, the hard polyvinyl chloride resin-based multilayer sheet of the present invention comprises a foam core layer made of a polyvinyl chloride resin composition containing a foaming agent and a rheology modifier, and one side of the foam core layer. Alternatively, it is characterized by comprising a non-foamed surface layer made of a polyvinyl chloride resin composition containing an impact resistance modifier, which is laminated and integrated on both sides.

Further, the method for producing a rigid polyvinyl chloride resin-based multilayer sheet of the present invention comprises a polyvinyl chloride resin composition containing a foaming agent and a rheological property modifier and forming a foam core layer during extrusion molding. Melt kneading, on the other hand, a polyvinyl chloride resin composition containing an impact modifier and forming a non-foamed surface layer at the time of extrusion molding is melt kneaded, and one or both surfaces of the former resin composition, the latter The resin composition is laminated, and then coextrusion is performed.

In the present invention, the type of the polyvinyl chloride resin as the base is not particularly limited, and a vinyl chloride monopolymer or a copolymer of vinyl chloride and vinyl acetate, ethylene, propylene, etc. can be used. These can be used alone or as a mixture of two or more kinds. Among them, straight polyvinyl chloride having an average degree of polymerization of 600 to 1400 is preferably used.

In the present invention, the flow characteristic modifier is
By blending with a polyvinyl chloride resin, it has the effect of reducing the viscosity of the polyvinyl chloride resin.

Examples of the flow property modifier include chlorinated polyethylene, ethylene-vinyl acetate copolymer and the like, and are not particularly limited. Among them, chlorinated polyethylene is particularly preferable. preferable.

The chlorinated polyethylene is obtained by chlorinating polyethylene powder or particles in an aqueous suspension, or chlorinating polyethylene dissolved in an organic solvent. The chlorinated polyethylene generally has a chlorine content of 25 to 45% by weight and is amorphous, and particularly preferably has a chlorine content of 27 to 40% by weight and is amorphous.

The number average molecular weight of the chlorinated polyethylene is preferably 30,000 to 250,000,
Above all, it is more preferably 50,000 to 250,000. When it is less than 30,000, the crystallinity of chlorinated polyethylene becomes high, and the directional dependence of the physical properties of the multilayer sheet becomes large. On the other hand, when it exceeds 250,000, the effect of improving the fluidity cannot be sufficiently obtained. The Mooney viscosity (MS1 + 4, 100 ° C) of this chlorinated polyethylene is 25-
It is preferably 90, and more preferably 30 to 80. If it is less than 25, suitable flow characteristics can be obtained by blending a small amount of chlorinated polyethylene, but it becomes difficult to impart sufficient impact resistance at the same time with this blending amount of a small amount. On the other hand, when it exceeds 90, the effect of improving the fluidity cannot be sufficiently obtained.

The blending ratio of chlorinated polyethylene is preferably 5 to 15 parts by weight, more preferably 5 to 10 parts by weight, based on 100 parts by weight of the vinyl chloride resin. If it is less than 5 parts by weight, the effect of improving fluidity during processing is small, and if it exceeds 15 parts by weight, other mechanical properties of the composition are deteriorated.

In the present invention, examples of the impact resistance modifier to be blended with the vinyl chloride resin include acrylic modifier, methacrylic acid ester-butadiene-styrene copolymer system modifier, ethylene-vinyl acetate copolymer system modifier. Examples thereof include a denaturant and an acrylsilicon type modifier, but the invention is not limited thereto.

As the impact resistance modifier to be blended with the polyvinyl chloride resin composition forming the core layer of the foam, an acrylic silicone impact resistance modifier is preferably used. The acryl-silicone impact modifier is a polysiloxane having a functional group (for example, an alkoxy group) at a molecular end or a side chain and a polyacrylate containing a functional group (for example, a hydroxyalkyl group) that reacts with the functional group or Graft-polymerized thermoplastic elastomer or resin with / and polymethacrylate. Methbrene S-2001 is a commercially available product of the acrylic silicone impact modifier.
(Made by Mitsubishi Rayon Co., Ltd.). In the present invention, the compounding amount of the acrylic silicon-based impact modifier added to the polyvinyl chloride resin composition forming the core layer is 1 to 100 parts by weight of the vinyl chloride resin.
It is preferably 15 parts by weight, and more preferably 3 to 10 parts by weight. If it is less than 1 part by weight, the effect of improving the impact strength is small, and if it exceeds 15 parts by weight, the fluidity during processing is significantly impaired.

180 to 1 of the foam forming the core layer
The viscosity at 90 ° C. should be adjusted to obtain suitable flow characteristics.
It is preferably in the range of 20,000 to 100,000 poise. Here, the viscosity is a viscosity measured at a shear rate of 100 / sec using a Capillograph (manufactured by Toyo Seiki Seisakusho, Ltd., barrel diameter: 9.55 mm, nozzle diameter: 1 mm, nozzle length: 10 mm). .

The foaming agent used in the present invention includes:
As a chemical foaming agent, azodicarbonamide, azobisisobutyronitrile, diazoaminobenzene, N, N '
-Dinitrosopentamethylenetetramine, N, N'-dimethyl-N, N'-dinitroterephthalamide, benzenesulfonylhydrazide, p-trienesulfonylhydrazide, p, p'-oxybisbenzenesulfonylhydrazide, carbonate, organic acid salt And propane, butane, pentane, methanol, ethanol and the like. Of course, these foaming agents may be used in combination with commonly used foaming aids, crosslinking agents, and nucleating agents, and the foams may be crosslinked.

A polyvinyl chloride resin composition containing the above-mentioned foaming agent and forming a foam layer in an extruder or a die has a foaming ratio of 1.1 to 5.0 times, preferably 1.
It is necessary to select conditions such as temperature so that foaming is sufficiently performed in the range of 2 to 4.0 times.

In the present invention, the polyvinyl chloride resin composition forming the foam core layer is intended to improve various properties of the multilayer sheet in addition to the polyvinyl chloride resin, the foaming agent and the flow characteristic modifier. As appropriate, various additives commonly used in vinyl chloride resins such as impact modifiers, stabilizers, lubricants, plasticizers, fillers, colorants, antistatic agents, ultraviolet absorbers, antioxidants, etc. are appropriately mixed. You can. Further, various polymers can be blended within a range that does not impair the properties of the multilayer sheet of the present invention.

Further, in the polyvinyl chloride resin composition forming the non-foamed surface layer, in addition to the polyvinyl chloride resin and the impact modifier, a stabilizer is added for the purpose of improving various properties of the multilayer sheet. Various additives commonly used for vinyl chloride resins such as a lubricant, a plasticizer, a filler, a colorant, an antistatic agent, an ultraviolet absorber and an antioxidant may be appropriately blended. further,
Various polymers may be blended within a range not impairing the properties of the multilayer sheet of the present invention.

In the present invention, when the above-mentioned respective material components are blended, they may be blended in a conventional manner.

The layer structure of the multilayer sheet of the present invention is such that one side or both sides of the polyvinyl chloride resin composition forming the core layer of the foam is coated with the polyvinyl chloride resin composition forming the non-foaming surface layer. It has a two-layer structure or a three-layer structure.

Regarding the thickness of each resin layer, the expansion ratio of the polyvinyl chloride resin composition forming the core layer of the foam and the mechanical properties of the polyvinyl chloride resin composition forming the non-foaming surface layer are in balance. However, normally, the thickness ratio of the non-foamed surface layer is preferably about 0.1 to 0.7 with respect to the total thickness.

In the present invention, the sheet stacking method is as follows.
Any method may be used as long as the polyvinyl chloride resin composition forming the core layer of the foam and the polyvinyl chloride resin composition forming the non-foaming surface layer are laminated in a molten state before coextrusion. As such a method, generally, a multi-manifold method in which both resins are melt-kneaded by respective extruders and then laminated in a T die, a feed block method in which they are laminated before flowing into the T die, and the like can be mentioned. To be When laminating another layer on the multilayer sheet thus produced, dry laminating, wet laminating, extrusion laminating,
A commonly used lamination method such as coextrusion or pressing may be used.

[0026]

Next, specific embodiments of the present invention will be described.

<Examples 1 to 7, Comparative Examples 1 to 3> The materials shown in Table 1 were blended in the proportions shown in Table 2 to form a polyvinyl chloride resin composition for forming a core layer of a foam and a non-vinyl chloride resin composition. The polyvinyl chloride resin compositions forming the foamed surface layer were mixed with a Henschel mixer. Next, each extruder was melted and kneaded, and these kneaded materials were laminated in three layers by a multi-manifold method, which was extruded from a T die and cooled.

The extruder has a diameter of 40 m for a polyvinyl chloride resin composition forming a non-foamed surface layer.
m, for the polyvinyl chloride resin composition that forms the core layer of the foam, use one with a diameter of 55 mm,
The T die used had a width of 550 mm.

The above-mentioned three-layer structure is a two-layer, three-layer polyvinyl chloride resin composition (thickness 1 mm) that forms a non-foamed layer.
/ Polyvinyl chloride resin composition (thickness 3 mm) that forms the core layer of the foam / Polyvinyl chloride resin composition (thickness 1 mm) that forms the non-foamed layer, and the foam is cooled by a metal 3 It was done with this roll.

[0030]

[Table 1]

[0031]

[Table 2]

<Comparative Examples 4 to 6> A system in which the polyvinyl chloride resin composition forming the non-foamed surface layer in the above Examples is not laminated. That is, the materials shown in Table 1 were blended in the proportions shown in Table 3, then mixed in a Henschel mixer, then melt-kneaded in an extruder, extruded from a T-die and cooled. The foam was cooled by a three-roll metal roll. The thickness of the sheet was 5 mm. The extruder has a caliber of 55
mm, and the T die had a width of 550 mm.

[0033]

[Table 3]

<Test Method and Evaluation Method> Each of the sheets produced as described above was evaluated according to the test methods shown in the following A to E. The results are shown in Table 4.

A. Izod impact strength test method (ASTM
According to D256) A test piece is prepared by making a notch with a depth of 2.54 mm in the center of a sheet of 65 mm x 12.7 mm (width) x 5 mm (thickness). Using the Izod impact strength tester, fix one end of the test piece with the notch and the other end from the notch 2
The surface on the same side as the cutout portion was ruptured by a single impact with a hammer at positions separated by 2 mm, and the Izod impact value at that time was measured.

As the Izod impact value, the following two values were measured. That is, one of the test pieces was cut out so that the flow direction during extrusion molding was the same as the direction along the cutout portion of the test piece when the test piece was cut out, and the Izod impact value was measured (in Table 4). , MD). On the other hand, when cutting out the test piece, the flow direction at the time of extrusion molding was cut out so as to be perpendicular to the direction along the cutout portion of the test piece, and the Izod impact value was measured (Table Four
(Abbreviated as TD).

B. Flexural modulus test method (ASTM D79
A sheet of 116 mm × 12.7 mm (width) × 5 mm (thickness) is used as a test piece. Using a bending tester, the distance between fulcrums was 80 mm, the crosshead moving speed was 2.5 mm / min, a load was applied to one point on the sheet at the center between the fulcrums, and the bending elastic modulus at that time was measured. Similar to the Izod impact strength test method, two types of values, MD and TD, were measured.

C. Bending strength test method (ASTM D790
The same as the flexural modulus test method. That is, the bending strength was measured at the same time when the bending elastic modulus was measured in the bending elastic modulus test. MD, T as in the Izod impact strength test method
Two values of D were measured.

D. Specific gravity test method 100 mm (length) x 100 mm (width) x 5 mm (thickness)
The sheet is used as a test piece. Measure the length of 3 points in the vertical direction and calculate the average value, measure the length of 3 points in the horizontal direction to calculate the average value, and measure the length of 4 points in the thickness direction to calculate the average value. Then, the volume of the test piece was determined from these, and the weight of the test piece was measured. The specific gravity was determined by weight (g) / volume (cm ³ ) (strictly, the density of water at 4 ° C. is 0.999973 g / cm ³ , but substantially 1
It was calculated as a g / cm ^3).

E. Workability test method The appearance of the foamed layer of the molded product was evaluated based on the following criteria. (Criteria) Foam cells are uniform and fine and have good appearance. ○ Foam cells are uniform, but the effect of foaming is recognized on the surface. △ Foam cells are uneven and foam skin is rough.

[0041]

[Table 4]

<Evaluation Results> As is clear from Table 4, the multilayer sheets of Examples 1 to 7 of the present invention are light in weight, have sufficient rigidity and impact resistance, and have directional dependence of physical properties. Is less and has excellent production processability.

On the other hand, the multilayer sheets of Comparative Examples 1 to 3 which deviate from the gist of the present invention are lightweight, but have problems in impact resistance and production processability. Although the sheets of Comparative Examples 4 to 6 are lightweight, they have problems in rigidity, impact resistance, and production processability.

[0044]

As described above, the hard polyvinyl chloride resin-based multilayer sheet of the present invention comprises a foam core layer made of a polyvinyl chloride resin composition containing a foaming agent and a flow property modifier, and the foamed core layer. Since it is composed of a non-foamed surface layer composed of a polyvinyl chloride resin composition containing an impact resistance modifier, which is laminated and integrated on one side or both sides of the body core layer, it is lightweight, has rigidity and impact resistance. And a heat-deformation resistance, production processability and appearance are excellent, and a multi-layer sheet having little directional dependence of physical properties can be formed.

In addition, in the present invention, when the composition in which the impact modifier is mixed with the polyvinyl chloride resin composition forming the foam core layer is adopted, in addition to the above-mentioned effects, it is more excellent. And a multilayer sheet having impact resistance.

Further, the method for producing a rigid polyvinyl chloride resin-based multilayer sheet of the present invention comprises a polyvinyl chloride resin composition containing a foaming agent and a rheological property modifier and forming a foam core layer during extrusion molding. Melt kneading, on the other hand, a polyvinyl chloride resin composition containing an impact modifier and forming a non-foamed surface layer at the time of extrusion molding is melt kneaded, and one or both surfaces of the former resin composition, the latter Since the resin composition is laminated and then coextruded, the load on the extruder at the time of extrusion molding can be reduced, and it is lightweight, and has rigidity, impact resistance, heat deformation resistance, and It is possible to produce a multi-layer sheet which is excellent in production processability and appearance and has little direction dependence of physical properties.

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Claims (6)

[Claims] 1. A foam core layer made of a polyvinyl chloride resin composition containing a foaming agent and a flow property modifier, and an impact resistance modified by laminating integrally on one side or both sides of the foam core layer. A hard polyvinyl chloride resin-based multilayer sheet comprising a non-foamed surface layer made of a polyvinyl chloride resin composition containing a substance. 2. A chlorinated polyethylene is used as the flow characteristic modifier, and the compounding amount of the chlorinated polyethylene is 5 to 15 parts by weight with respect to 100 parts by weight of the vinyl chloride resin. The hard polyvinyl chloride resin-based multilayer sheet according to claim 1. 3. The hard poly according to claim 1, wherein the polyvinyl chloride resin composition containing the foaming agent and the rheological property modifier is blended with an impact resistance modifier. Vinyl chloride resin-based multi-layer sheet. 4. An acrylic silicon-based modifier is used as an impact resistance modifier to be blended with a polyvinyl chloride resin composition containing the foaming agent and the flow property modifier, and the acrylic silicon-based modifier is used. The hard polyvinyl chloride resin-based multilayer sheet according to claim 3, wherein the blending amount of the substance is 1 to 15 parts by weight with respect to 100 parts by weight of the vinyl chloride resin. 5. A foaming agent and a rheological property modifier are contained,
A polyvinyl chloride resin composition that forms a foam core layer during extrusion molding is melt-kneaded, while a polyvinyl chloride resin composition that contains an impact resistance modifier and forms a non-foaming surface layer during extrusion molding is prepared. A method for producing a rigid polyvinyl chloride resin-based multilayer sheet, which comprises melt-kneading, laminating the latter resin composition on one or both sides of the former resin composition, and then performing coextrusion. 6. The method for producing a rigid polyvinyl chloride resin-based multilayer sheet according to claim 5, wherein the viscosity of the foam at 180 to 190 ° C. is set in the range of 2000 to 100000 poise.