JP2005187644A - Vinyl chloride-based polymer composition and molded product molded from the composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vinyl chloride-based polymer composition having excellent toughness at a fracture mode such as crack growth properties in long-time use while keeping the high modulus peculiar to a vinyl chloride-based polymer without damaging characteristics of tensile elongation. <P>SOLUTION: The vinyl chloride-based polymer composition is obtained by dispersing a swelling phyllosilicate and a vinyl acetate-ethylene-based copolymer in a vinyl chloride-based polymer, and satisfies the following conditions: (A) the vinyl chloride-based polymer has ≥600 average degree of polymerization; (B) the swelling phyllosilicate dispersed in the composition has 0.5-100 nm average layer thickness, and ≥5 average aspect ratio (ratio of the length of the layer to the thickness of the layer); (C) the vinyl acetate-ethylene-based copolymer dispersed in the composition has a particle shape having 10-1,000 nm average diameter; and (D) a part or the whole of the swelling phyllosilicate has a shape dispersed in the vinyl acetate-ethylene-based copolymer particles. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a vinyl chloride polymer composition from which a molded article having an excellent fracture toughness value can be obtained without losing tensile elongation characteristics while maintaining a high elastic modulus, and a molded article obtained from the composition. .

  The vinyl chloride polymer and its composition are excellent in rigidity, weather resistance, flame retardancy, etc., and are inexpensive and highly productive. Widely used in fields such as sheets. Among these, in pipe applications and the like, the long-term durability of the pipe, such as crack progress in long-time use accompanying cracks that occur during use and construction, has become a problem. In order to improve long-term durability, it is known that it is effective to improve the toughness of the molded body, that is, to improve the fracture toughness value.

  Fracture toughness value is an evaluation of the difficulty of crack growth due to stress concentration in the vicinity of a notch when a load is applied to a molded product for a long time. For example, in the case of evaluating by a three-point bending test The fracture toughness value Kc is calculated from the maximum stress that breaks. Moreover, when evaluating by a creep test, the fracture toughness value Kc is calculated from the magnitude of the load required to break in a certain time. Therefore, in order to improve the fracture toughness value, the magnitude of the stress necessary for causing the crack to grow is important, and a material having both ductility and rigidity is required rather than merely a ductile material.

  Patent Document 1 discloses a technique for adding a small amount of a fracture performance agent (stretchability imparting agent) such as chlorinated polyethylene to a vinyl chloride polymer as a technique for improving the fracture toughness value of a vinyl chloride plastic pipe. ing. These technologies promote the improvement of the fracture toughness value of the vinyl chloride polymer, but it is necessary to uniformly disperse a small amount of the fracture performance agent in the vinyl chloride polymer. Measures such as lengthening or strengthening are required. Therefore, despite the increased cost of molded products and improved fracture toughness values, there are concerns about the technical bottleneck that other performances such as deterioration of molded appearance and lowering of elastic modulus cannot be drawn out, and the technology is always satisfactory. I can't say that.

On the other hand, a method of adding an inorganic filler such as calcium carbonate, talc, or mica to the vinyl chloride polymer is generally used to impart rigidity to the vinyl chloride polymer.
In this case, the elastic modulus improves as the inorganic filler is more finely dispersed. For example, layered swellable silicate is an inorganic mineral formed by agglomerating very fine flaky crystals with a thickness of about 1 nm in layers by ionic bonds. This layered structure is a chemical or physical means. By exfoliating and dispersing flaky crystals in a polymer material at a nanometer level, heat resistance and gas barrier properties as well as elastic modulus are remarkably improved compared to the addition of conventional inorganic fillers. This has been known in recent years.

  Patent Document 2 discloses a technique for improving elastic modulus and heat resistance by finely dispersing a layered swellable silicate that has been made organic with a specific amino compound into a vinyl chloride polymer to a nanometer level. Has been. However, in these disclosed techniques, the rigidity is improved, but the ductility is remarkably reduced, and the amino compound used as an affinity improver for the vinyl chloride polymer and the layered swellable silicate is vinyl chloride. It is still insufficient for use as an industrial material by promoting the thermal decomposition of the polymer.

  In Patent Document 3, a specific amount of a layered swellable silicate in which a part of exchangeable inorganic ions existing between layers is replaced with a cation is finely dispersed at a nanometer level in a vinyl chloride polymer. A technique for improving the fracture toughness value is disclosed. However, there is a drawback that the hue of the molded article from which the organic cation used is obtained is deteriorated, and an improvement thereof is desired.

In Patent Document 4, when a vinyl chloride monomer is polymerized in an aqueous medium in the presence of a polymerization initiator, a specific amount of a layered swellable silicate is added, and the vinyl chloride resin is nano-sized. A technique for improving the fracture toughness value by dispersing a layered swellable silicate at a meter level size is disclosed. However, these techniques have the disadvantage that the manufacturing process becomes complicated and the manufacturing cost increases, and are still insufficient for use as industrial materials.
Japanese National Patent Publication No. 4-500402 JP 2000-159962 A JP 2003-231786 A JP 2003-231787 A

  The present invention has been made in view of the above-described circumstances, and maintains a high elastic modulus unique to a vinyl chloride polymer, and does not impair tensile elongation characteristics, and a fracture mode such as crack progressability during long-time use. An object of the present invention is to provide a vinyl chloride polymer composition excellent in toughness and a molded product obtained from the composition.

The present invention for solving the above problems is specified by the following matters.
(1) In a vinyl chloride polymer composition obtained by dispersing a layered swellable silicate and a vinyl acetate-ethylene copolymer in a vinyl chloride polymer,
(A) The vinyl chloride polymer has an average degree of polymerization of 600 or more,
(B) The layered swellable silicate dispersed in the composition has an average layer thickness of 0.5 to 100 nm as measured with an electron microscope and an average aspect ratio (ratio of layer length to layer thickness) of 5 or more. ,
(C) The vinyl acetate-ethylene copolymer dispersed in the composition has a particle shape with an average diameter of 10 to 1000 nm measured with an electron microscope, and
(D) A vinyl chloride polymer composition characterized in that a part or all of the layered swellable silicate has a form dispersed in the vinyl acetate-ethylene copolymer particles.

  (2) The vinyl chloride polymer composition according to (1), wherein the vinyl acetate-ethylene copolymer contains 2 to 60% by mass of vinyl acetate in a mass ratio.

  (3) The chloride according to (1) or (2), wherein the vinyl acetate-ethylene copolymer contains 1 to 40% by mass of vinyl alcohol in a mass ratio by partial saponification of vinyl acetate. Vinyl polymer composition.

  (4) The vinyl chloride polymer composition according to any one of (1) to (3), wherein the vinyl acetate-ethylene copolymer is modified with maleic acid.

  (5) The content ratio of the layered swellable silicate and the vinyl acetate-ethylene copolymer in the composition is 80:20 to 20:80 by mass ratio (1) to (4) ). The vinyl chloride polymer composition according to any one of 1).

  (6) The layered swellable silicate contains 0.05 to 10% by mass of the composition as a residue when the composition is completely burned at 950 ° C. (1) to (5) ). The vinyl chloride polymer composition according to any one of 1).

(7) The vinyl chloride polymer composition according to any one of (1) to (6), wherein a fracture toughness value measured according to ASTM D5045-99 is 3.1 MPa · m ^1/2 or more.

  (8) A molded product obtained by molding the vinyl chloride polymer composition according to any one of (1) to (7).

  (9) The molded product according to (8), wherein the molded product is a pipe.

  According to the present invention, it is possible to obtain a vinyl chloride polymer composition capable of maintaining a high elastic modulus and obtaining a molded article having an excellent fracture toughness value without impairing tensile elongation characteristics.

  The present invention relates to a vinyl chloride polymer composition in which a layered swellable silicate having a specific particle shape and a vinyl acetate-ethylene copolymer are dispersed, and a molded product thereof, and has a fracture toughness value (ASTM D5045). The long-term durability and rigidity of the obtained molded product are made compatible by optimizing the composition and dispersion mode using an index of (measured according to -99).

  That is, the vinyl chloride polymer composition of the present invention contains a vinyl acetate-ethylene copolymer as an affinity improver for a vinyl chloride polymer and a layered swellable silicate, In the polymer, layered swellable silicate is finely dispersed with an average layer thickness of 0.5 to 100 nm and an average aspect ratio of 5 or more, and part or all of these layered swellable silicates That is, 50 to 100 mass%, preferably 70 to 100 mass%, more preferably 80 to 100 mass% of the layered swellable silicate contained therein has an average diameter of 10 to 10 in the vinyl chloride polymer. A hierarchical structure dispersed in vinyl acetate-ethylene copolymer particles finely dispersed with a size of 1000 nm is formed. By forming such a structure, while maintaining a high elastic modulus, the fracture toughness value is remarkably improved without impairing the elongation characteristics, and the long-term durability of the molded product, specifically, crack growth during long-term use It is possible to improve the toughness in the fracture mode such as property.

  The reason for this is not necessarily clear, but the structure of the molded product obtained in the present invention is a flaky layered swellable silicate finely dispersed in a nanometer order size when observed with a transmission electron microscope. And a multilayer in which vinyl acetate-ethylene copolymer particles containing a part or all of them are dispersed in a network so as to cover the interface of the residual particle structure of the vinyl chloride polymer without overlapping. Because of the structure, when expansion stress occurs in the molded product, many crazes and microvoids are formed by dispersing stress concentration points at the residual particle structure interface without impairing the rigidity of the residual particle structure interface itself. It is considered that the local plastic deformation of the interface accompanied by the phenomenon becomes possible, and the fracture toughness value is improved.

  In this case, the layered swellable silicate or vinyl acetate-ethylene copolymer is poorly dispersed, that is, the affinity of the three components of the vinyl chloride polymer, the layered swellable silicate, and the vinyl acetate-ethylene copolymer. The balance of properties is insufficient, and the layered swellable silicate is not encapsulated in the vinyl acetate-ethylene copolymer, and the lamellar crystals of the layered swellable silicate aggregate in the vinyl chloride polymer. The vinyl acetate-ethylene copolymer becomes a vinyl chloride polymer even if the layered swellable silicate is dispersed and encapsulated in the vinyl acetate-ethylene copolymer. If the particles are dispersed in a large particle shape, these large aggregate structures behave as structural defects, promote crack propagation, and lower the fracture toughness value. Therefore, in order to obtain a molded article having a high fracture toughness value, the layered swellable silicate and the vinyl acetate-ethylene copolymer containing a part or all of the swellable silicate are of the above-mentioned nano-order level. Need to be finely dispersed.

In the present invention, the fracture toughness value is improved by the above-mentioned means, but the fracture toughness value is preferably 3.1 MPa · m ^1/2 or more, more preferably 3.7 MPa · m ^1/2 or more, most preferably Is 3.9 MPa · m ^1/2 or more. Here, the measurement of the fracture toughness value can be obtained by a three-point bending test using a flat plate having a notch on one side, in accordance with ASTM D-5045-95. By setting the fracture toughness value as described above, a molded product having excellent long-term durability can be obtained. There is no particular upper limit on the fracture toughness value, but for example, about 6 MPa · m ^1/2 is sufficient. As will be described later in Examples and the like, according to the present invention, a high fracture toughness value Kc can be obtained without impairing the elastic modulus of a molded product, and a high-quality vinyl chloride polymer composition is provided.

  The vinyl chloride polymer in the present invention is a homopolymer of vinyl chloride, a copolymer of vinyl chloride and another vinyl monomer copolymerizable with vinyl chloride, further vinyl chloride, if necessary. Examples thereof include partially cross-linked vinyl chloride polymers by copolymerization with other vinyl monomers and polyfunctional monomers that can be copolymerized.

  Examples of other vinyl monomers copolymerizable with vinyl chloride include α-monoolefin monomers such as ethylene, propylene and butylene; vinyl esters such as vinyl acetate and vinyl propionate; methyl vinyl ether, Alkyl vinyl ethers such as cetyl vinyl ether; styrene derivatives such as styrene and α-methylstyrene; (meth) acrylic esters such as n-butyl acrylate, 2-ethylhexyl acrylate and methyl methacrylate; vinyl cyanides such as acrylonitrile and methacrylonitrile N-substituted maleimides such as cyclohexylmaleimide and phenylmaleimide; vinylidenes such as vinylidene chloride; and at least one of them is copolymerized with vinyl chloride.

  In addition, as the polyfunctional monomer to be partially crosslinked, polyfunctional allyl compounds such as diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl fumarate, diallyl adipate, triallyl cyanurate; ethylene glycol divinyl ether, octadecane divinyl ether, etc. Polyfunctional vinyl ethers; 1,3-butylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) And polyfunctional (meth) acrylates such as acrylate. At least one of these is copolymerized with vinyl chloride to obtain a vinyl chloride polymer having a partially crosslinked structure.

  The average degree of polymerization of the vinyl chloride polymer is 600 or more. The fracture toughness value of the molded product obtained by setting it as this range can be made favorable. When the average degree of polymerization of the vinyl chloride polymer is less than 600, the effect of improving the fracture toughness value cannot be obtained. Here, when the average degree of polymerization of the vinyl chloride polymer is 600 to 3000, preferably 700 to 2000, the balance between fracture toughness value and moldability is further improved, the fluidity during molding is good, and the molding machine A molded product having a low kneading torque and a high fracture toughness value is preferable.

  The vinyl chloride polymer may be produced by any of the suspension polymerization method, emulsion polymerization method, solution polymerization method, bulk polymerization method and the like, and is not particularly limited, but was produced by the suspension polymerization method. Those having less residual monomer are preferred.

  The suspension polymerization method for vinyl chloride polymers is well known, and any known method may be used without any particular limitation.

  The layered swellable silicate in the present invention has a structure in which flaky crystals mainly composed of a tetrahedral sheet of silicon oxide and an octahedral sheet of metal hydroxide are stacked in layers, sodium ions between the layers, It is a water-soluble silicate mineral having exchangeable cations such as calcium ions. The type of layered swellable silicate is not particularly limited. For example, smectite clay minerals such as montmorillonite, saponite, hectorite, beidellite, nontrironite, soconite, bentonite, and vermiculite, halloysite, or swelling Examples include natural mica and the like, which may be natural or synthesized. Among them, use of montmorillonite, bentonite, and swellable mica is preferable from the viewpoint of easy availability and improvement of physical properties.

  The vinyl acetate-ethylene copolymer in the present invention is a multi-dimensional random copolymer of ethylene and vinyl acetate as essential components and, if necessary, ethylene or other vinyl monomers copolymerizable with vinyl acetate. , Block copolymers, graft copolymers and the like.

  Examples of other vinyl monomers copolymerizable with ethylene or vinyl acetate used here include α-monoolefin monomers such as propylene and butylene; vinyl esters such as vinyl propionate; methyl vinyl ether, cetyl vinyl ether, etc. Alkyl vinyl ethers of styrene; styrene derivatives such as styrene and α-methylstyrene; (meth) acrylic esters such as n-butyl acrylate, 2-ethylhexyl acrylate and methyl methacrylate; vinyl cyanides such as acrylonitrile and methacrylonitrile; cyclohexylmaleimide N-substituted maleimides such as phenylmaleimide; vinylidenes such as vinylidene chloride, vinyl chloride and the like, at least one of which is copolymerized with ethylene or vinyl acetate.

  The molecular weight of the ethylene-vinyl acetate copolymer used in the present invention is not particularly limited, but if the weight average molecular weight is in the range of 1000 to 5000000, a molded product having good moldability and high fracture toughness value can be obtained. Obtained and preferred.

  Moreover, there is no restriction | limiting in particular also about the manufacturing method of an ethylene- vinyl acetate type copolymer, You may use a well-known method.

  As described above, the composition of the vinyl acetate-ethylene copolymer used in the present invention is not limited at all except that vinyl acetate and ethylene are essential components. Preferably, the vinyl acetate content is as a mass ratio. It is 2-60 mass%, More preferably, it is 3-40 mass%. When the vinyl acetate content is within the above range, the balance of the affinity of the three components of the vinyl chloride polymer, the layered swellable silicate, and the vinyl acetate-ethylene copolymer is improved, and the layered swellable silicic acid is obtained. The dispersibility of the salt and the vinyl acetate-ethylene copolymer is good, and a molded article having a high fracture toughness value is obtained, which is preferable.

  Further, when the vinyl acetate-ethylene copolymer used in the present invention contains 1 to 40% by mass, preferably 5 to 30%, of vinyl alcohol substituted by partial saponification of vinyl acetate, layered swelling properties The dispersibility of the silicate and the vinyl acetate-ethylene copolymer is further improved, and a molded article having a high fracture toughness value is obtained, which is more preferable.

  The method for producing the partially saponified vinyl acetate-ethylene copolymer is not particularly limited, and may be a known method. For example, a method in which vinyl acetate-ethylene copolymer is immersed in methanol in which sodium hydroxide is dissolved to hydrolyze vinyl acetate can be mentioned.

   Further, when the vinyl acetate-ethylene copolymer used in the present invention is a maleic acid-modified vinyl acetate-ethylene copolymer, the layered swellable silicate and the vinyl acetate-ethylene copolymer A dispersibility is further improved, and a molded article having a high fracture toughness value is obtained, which is more preferable.

  The method for producing the maleic acid-modified vinyl acetate-ethylene copolymer is not particularly limited, and may be a known method. For example, there is a method in which a vinyl acetate-ethylene copolymer is melt-kneaded with maleic anhydride in the presence of an organic peroxide and ethylene or vinyl acetate is modified with maleic acid by a radical reaction.

  In the present invention, the layers of the layered swellable silicate are separated from each other in the molded product, and have a form dispersed in flaky crystal units as much as possible, and a part of these layered swellable silicates or All need to have the form of a hierarchical structure dispersed in vinyl acetate-ethylene copolymer particles finely dispersed in the molded body.

  Accordingly, the shape of the layered swellable silicate used in the present invention in the state of being dispersed in the molded product has an average layer thickness of 0.5 to 100 nm and an average aspect ratio (of the layer length and the layer thickness). Ratio) is 5 or more. Preferably, the average layer thickness is 0.5 to 80 nm and the average aspect ratio is 7 to 300. More preferably, the average layer thickness is 0.5 to 60 nm and the average aspect ratio is 10 to 300.

  When the average layer thickness of the layered swellable silicate dispersed in the molded product exceeds 100 nm or the average aspect ratio is less than 5, the layered swellable silicate has insufficient delamination. Thus, a large number of flaky crystals tend to be aggregated, which becomes a structural defect, and a high fracture toughness value cannot be obtained.

  Furthermore, the form dispersed in the molded article of the vinyl acetate-ethylene copolymer used in the present invention is a particle shape having an average diameter of 10 to 1000 nm, preferably 10 to 700 nm, and the above-described size and Part or all of the layered swellable silicate dispersed in shape has a form dispersed in vinyl acetate-ethylene copolymer particles.

  If the average diameter of the vinyl acetate-ethylene copolymer dispersed in the molded product exceeds 1000 nm, it becomes a structural defect, and a high fracture toughness value cannot be obtained. In addition, if the layered swellable silicate is not dispersed at all in the vinyl acetate-ethylene copolymer particles, the affinity between the vinyl chloride polymer and the layered swellable silicate is lacking. A high fracture toughness value cannot be obtained due to a decrease in the elastic modulus of the vinyl acetate-ethylene copolymer particles themselves, which is not preferable.

  The content ratio of the layered swellable silicate and the vinyl acetate-ethylene copolymer in the vinyl chloride polymer composition of the present invention is not particularly limited, but is preferably 80:20 by mass ratio. -20: 80, more preferably 70: 30-30: 70. When the content ratio is in the above-described range, the dispersibility of the layered swellable silicate and the vinyl acetate-ethylene copolymer in the molded article is improved, and a high fracture toughness value is obtained, which is more preferable.

  The content of the layered swellable silicate in the vinyl chloride polymer composition of the present invention is not particularly limited, but is preferably 0.05 to 10 mass as a weight fraction of the inorganic component. %, And more preferably 0.1 to 3 mass.

  By the way, the content of the layered swellable silicate is determined by completely burning the molded article of the obtained vinyl chloride polymer composition at 950 ° C. and measuring the mass of ash. Defined as mass fraction.

  The production method of the present invention is not particularly limited. For example, a predetermined amount of a vinyl chloride polymer, a layered swellable silicate, and a vinyl acetate-ethylene copolymer is blended, and various additions are added as necessary. It can be obtained by uniformly mixing the blended agent with a Henschel mixer, a rabies machine, a planetary mixer, and other various mixers. You may carry out by what is called a hot blend in the range of ° C. The vinyl chloride polymer composition produced by the above method is melt-kneaded in a predetermined shear stress field using a kneader such as a single screw extruder, a twin screw extruder, a roll kneader, or a Banbury mixer. By manufacturing the product, it is possible to form a structure in which the layered swellable silicate and the vinyl acetate-ethylene copolymer are finely dispersed in a nanometer order level in the molded product.

  In this case, only a predetermined amount of a layered swellable silicate and a vinyl acetate-ethylene copolymer is blended in advance, for example, by a kneader such as a single screw extruder, a twin screw extruder, a roll kneader, a Banbury mixer or the like. Then, after melt-kneading in a predetermined shear stress field, a vinyl chloride polymer and various additives as necessary are blended and re-melt-kneaded to produce a molded product, whereby the layered swellable silicate is previously obtained. Since it is covered with vinyl acetate-ethylene copolymer and melted and kneaded with vinyl chloride polymer in the state of peeling and dispersing to flaky crystal units, layered swellable silicate and vinyl acetate in the molded product -It is more preferable because the ethylene copolymer can be finely dispersed in a nanometer order level efficiently and uniformly.

  In the vinyl chloride polymer composition of the present invention, depending on the purpose, pigments and dyes, heat stabilizers, antioxidants, UV absorbers, light stabilizers, lubricants, plasticizers, flame retardants, processing aids, Additives such as impact resistance improvers and antistatic agents may be added.

  In addition, a molded article made of the composition of the present invention can be obtained by melt kneading and shaping by a known resin molding method, for example, press molding, extrusion molding, injection molding, blow molding, calendar molding, and the like. It is done. Although there is no restriction | limiting in particular about the temperature at the time of melt-kneading, The molded article which has a high elasticity modulus and a high fracture toughness value is obtained by shape | molding in the temperature range of 140-200 degreeC, and is preferable. In particular, the molded article made of the composition of the present invention is preferably used for building materials such as pipes, joints, rain gutters, window frames, sizing materials and the like. Among them, when a pipe is formed by extrusion molding, a pipe having high rigidity, a high fracture toughness value, and excellent long-term durability is more preferable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to this. The vinyl chloride polymer compositions obtained in the following examples and comparative examples were evaluated by the methods shown below.

(Measurement method of average degree of polymerization)
According to JIS-K6721, it was calculated by measuring the viscosity of a vinyl chloride polymer solution using nitrobenzene as a solvent. When the vinyl chloride polymer was not completely dissolved, the insoluble content was filtered, and the viscosity was calculated by measuring the viscosity of the soluble content.

(Method for producing molded product)
The obtained vinyl chloride polymer composition was kneaded with a roll at a temperature of 165 ° C. for 5 minutes to prepare a roll kneaded sheet, and this roll kneaded sheet was press-molded at 175 ° C. under a pressure of 15 MPa for 20 minutes. Then, a molded product was produced.

(Measurement method of average layer thickness and average aspect ratio of layered swellable silicate in molded product)
The molded product created above was cut into a 1 μm-thick piece with an ultramicrotome, observed with a transmission electron microscope (manufactured by JEOL Ltd., JEM-2000FX) at a magnification of 500,000 times, and in a 0.1 mm square. The layer thickness and layer length of the dispersed layered swellable silicate were measured, and the average layer thickness and average aspect ratio were calculated.

(Measuring method of average diameter of vinyl acetate-ethylene copolymer particles in molded product and presence / absence of layered swellable silicate in particles)
Microscopic observation was performed in the same manner as above, and the average diameter of the vinyl acetate-ethylene copolymer particles was measured and the presence or absence of a layered swellable silicate in the particles was observed.

(Measurement method of content of layered swellable silicate in molded product)
1 g was cut from the molded product prepared above, burned at 950 ° C. for 1 hour, and the content of the layered swellable silicate was calculated from the mass measurement of ash.

(Fracture toughness test method)
Fracture toughness from maximum stress by three-point bending test using a flat plate with a notch on one side using a tester (A & D, Tensilon) according to ASTM D-5045-95, using the molded product created above. The value (Kc) was calculated. In addition, about the molded article which showed the nonlinear fracture | rupture, the time to reach the maximum stress was regarded as the crack growth start point of the molded article, and the fracture toughness value (Kc) was calculated from the maximum stress.

(Measurement method of tensile modulus and elongation)
Using the molded article prepared above, the tensile modulus and elongation were measured with a testing machine according to JIS K 7113 (manufactured by A & D Corporation, Tensilon).

Example 1
As a vinyl chloride polymer, 300 g of a vinyl chloride polymer (manufactured by Taiyo PVC Co., Ltd .: trade name : TH-1000) produced by a suspension polymerization method having an average degree of polymerization of 1020, natural as a layered swellable silicate Montmorillonite (Kunimine Kogyo Co., Ltd., trade name: Kunipia F) purified from bentonite ore of 1.506 g, vinyl acetate-ethylene copolymer, vinyl acetate content 5% by mass, ethylene content 0.645 g of 95% by mass vinyl acetate-ethylene copolymer (manufactured by Tosoh Corporation: trade name: Petrocene 291R) as a stabilizer, dioctyltin mercapto-based stabilizer (manufactured by Sansha Co., Ltd .: commodity) (Name: ONZ-82BF) 3 g was mixed with a Henschel mixer, and kneaded and press-molded to prepare a vinyl chloride polymer composition.

  The content of montmorillonite determined from the ash content of the obtained molded product was 0.50% by mass, the montmorillonite was dispersed with an average layer thickness of 28 nm and an average aspect ratio of 12, and A part was dispersed inside the vinyl acetate-ethylene copolymer particles dispersed with an average diameter of 420 nm.

  Further, the obtained molded article had a high fracture toughness value, and had a high tensile elastic modulus and a high tensile elongation.

Example 2
A vinyl chloride polymer composition was prepared in the same manner as in Example 1 except that the vinyl acetate-ethylene copolymer (manufactured by Tosoh Corporation: trade name: Petrocene 291R) was changed to 1.506 g in Example 1. Produced.
The content of montmorillonite determined from the ash content of the obtained molded product is 0.49% by mass, the montmorillonite is dispersed with an average layer thickness of 18 nm and an average aspect ratio of 20, and A part was dispersed inside the vinyl acetate-ethylene copolymer particles dispersed with an average diameter of 380 nm.
Further, the obtained molded article had a high fracture toughness value, and had a high tensile elastic modulus and a high tensile elongation.

Example 3
A vinyl chloride polymer composition was prepared in the same manner as in Example 1, except that the vinyl acetate-ethylene copolymer (manufactured by Tosoh Corporation: Petrocene 291R) was changed to 3.519 g.
The content of montmorillonite determined from the ash content of the obtained molded product is 0.51% by mass, the montmorillonite is dispersed with an average layer thickness of 16 nm and an average aspect ratio of 18, and A part was dispersed inside the vinyl acetate-ethylene copolymer particles dispersed with an average diameter of 320 nm.
Further, the obtained molded article had a high fracture toughness value, and had a high tensile elastic modulus and a high tensile elongation.

Example 4
In Example 2, a vinyl acetate-ethylene copolymer was prepared by using a vinyl acetate-ethylene copolymer having a vinyl acetate content of 20% by mass and an ethylene content of 80% by mass (trade name: manufactured by Tosoh Corporation). A vinyl chloride polymer composition was prepared in the same manner as in Example 2 except that Ultrasen 631) was used.
The content of montmorillonite determined from the ash content of the obtained molded product is 0.48% by mass, the montmorillonite is dispersed with an average layer thickness of 30 nm and an average aspect ratio of 13, and A part was dispersed inside the vinyl acetate-ethylene copolymer particles dispersed with an average diameter of 510 nm.
Further, the obtained molded article had a high fracture toughness value, and had a high tensile elastic modulus and a high tensile elongation.

Example 5
In Example 2, except that Montmorillonite (Kunimine Kogyo Co., Ltd .: Kunipia F) was changed to 9.036 g and the vinyl acetate-ethylene copolymer (Tosoh Corp .: Petrocene 291R) was changed to 21.084 g. A vinyl chloride polymer composition was prepared in the same manner as in Example 2.
The content of montmorillonite determined from the ash content of the obtained molded product is 3.02% by mass, the montmorillonite is dispersed with an average layer thickness of 31 nm and an average aspect ratio of 12, and A part of the particles were dispersed inside vinyl acetate-ethylene copolymer particles dispersed with an average diameter of 430 nm.
Further, the obtained molded article had a high fracture toughness value, and had a high tensile elastic modulus and a high tensile elongation.

Example 6
In Example 2, a vinyl acetate-ethylene copolymer was partially saponified vinyl acetate having a vinyl acetate content of 17% by mass, an ethylene content of 78% by mass, and a vinyl alcohol content of 10% by mass. A vinyl chloride polymer composition was prepared in the same manner as in Example 2 except that the copolymer was changed to an ethylene copolymer (trade name: Mersen H manufactured by Tosoh Corporation).
The content of montmorillonite determined from the ash content of the obtained molded product is 0.49% by mass, the montmorillonite is dispersed with an average layer thickness of 21 nm and an average aspect ratio of 17, and A part was dispersed inside the partially saponified vinyl acetate-ethylene copolymer particles dispersed with an average diameter of 410 nm. Further, the obtained molded article had a high fracture toughness value, and had a high tensile elastic modulus and a high tensile elongation.

Example 7
In Example 2, a vinyl acetate-ethylene copolymer was prepared by adding a vinyl acetate-ethylene copolymer having a vinyl acetate content of 30% by mass and an ethylene content of 70% by mass in the presence of an organic peroxide. A vinyl chloride polymer composition was prepared in the same manner as in Example 2 except that it was changed to a maleic acid-modified vinyl acetate-ethylene copolymer obtained by melt-kneading with maleic anhydride and modified.
The content of montmorillonite determined from the ash content of the obtained molded product was 0.49% by mass, the montmorillonite was dispersed with an average layer thickness of 20 nm and an average aspect ratio of 16, and A part was dispersed inside the maleic acid-modified vinyl acetate-ethylene copolymer particles dispersed with an average diameter of 370 nm. Further, the obtained molded article had a high fracture toughness value, and had a high tensile elastic modulus and a high tensile elongation.

Example 8
In Example 2, the layered swellable silicate was changed to finely pulverized bentonite (Kunimine Kogyo Co., Ltd .: prototype) obtained by classifying and pulverizing natural bentonite ore into particles having an average diameter of 1 μm. A vinyl chloride polymer composition was prepared in the same manner as in Example 2 except that the amount added was 2.154 g.
The bentonite content determined from the ash content of the obtained molded product is 0.70% by mass, the bentonite is dispersed with an average layer thickness of 40 nm and an average aspect ratio of 12, and A part was dispersed inside the vinyl acetate-ethylene copolymer particles dispersed with an average diameter of 520 nm. Further, the obtained molded article had a high fracture toughness value, and had a high tensile elastic modulus and a high tensile elongation.

Example 9
Example 2 is the same as Example 2 except that the vinyl chloride polymer was changed to a vinyl chloride polymer produced by a suspension polymerization method with an average degree of polymerization of 1710 (manufactured by Taiyo PVC Co., Ltd .: TH-1700). Similarly, a vinyl chloride polymer composition was prepared.

  The content of montmorillonite determined from the ash content of the obtained molded product was 0.48% by mass, bentonite was dispersed with an average layer thickness of 18 nm and an average aspect ratio of 21; A part of the particles were dispersed inside vinyl acetate-ethylene copolymer particles dispersed with an average diameter of 460 nm. Further, the obtained molded article had a high fracture toughness value, and had a high tensile elastic modulus and a high tensile elongation.

Example 10
30 g of montmorillonite purified from natural bentonite ore (Kunimine Kogyo Co., Ltd .: Kunipia F) as a layered swellable silicate, a vinyl acetate-ethylene copolymer having a vinyl acetate content of 5% by mass, ethylene 30 g of a vinyl acetate-ethylene copolymer (Tosoh Co., Ltd .: Petrocene 291R) having a content of 95% by mass is placed in a plast mixer (Toyo Seiki Co., Ltd .: Labo Plast Mill) at a temperature of 140 ° C. The resulting mixture was melt-kneaded for 5 minutes, and 3.012 g of a crushed mixture of the resulting vinyl acetate-ethylene copolymer and montmorillonite was produced as a vinyl chloride polymer by suspension polymerization with an average degree of polymerization of 1020. 300 g of vinyl chloride polymer (manufactured by Taiyo PVC Co., Ltd .: TH-1000) as a stabilizer, dioctyltin mercapto-based stabilizer (Three sharing machine ( 3 g of ONZ-82BF) was mixed with a Henschel mixer, kneaded in a roll and press-molded to prepare a vinyl chloride polymer composition. The content of montmorillonite determined from the ash content of the obtained molded product was 0.49% by mass, the montmorillonite was dispersed with an average layer thickness of 15 nm and an average aspect ratio of 16, and A part was dispersed inside the vinyl acetate-ethylene copolymer particles dispersed with an average diameter of 250 nm. Further, the obtained molded article had a high fracture toughness value, and had a high tensile elastic modulus and a high tensile elongation.

Example 11
In Example 2, a vinyl acetate-ethylene copolymer was prepared by using a vinyl acetate-ethylene copolymer having a vinyl acetate content of 70% by mass and an ethylene content of 30% by mass (manufactured by Nippon Synthetic Chemical Industry Co., Ltd .: A vinyl chloride polymer composition was prepared in the same manner as in Example 2 except that the product name was changed to (trade name: Soaprene). The content of montmorillonite determined from the ash content of the obtained molded product was 0.49% by mass, the montmorillonite was dispersed with an average layer thickness of 60 nm and an average aspect ratio of 8, and A part was dispersed inside the vinyl acetate-ethylene copolymer particles dispersed with an average diameter of 520 nm. Further, the obtained molded article had a high fracture toughness value, and had a high tensile elastic modulus and a high tensile elongation.

Comparative Example 1
In Example 2, 300 g of a vinyl chloride polymer (manufactured by Taiyo PVC Co., Ltd .: TH-1000), montmorillonite (Kunimine Industry Co., Ltd .: Kunipia F) and a vinyl acetate-ethylene copolymer (manufactured by Tosoh Corp.) : A vinyl chloride polymer composition was prepared in the same manner as in Example 2 without adding any petrocene 291R).
The content of montmorillonite determined from the ash content of the obtained molded product was 0% by mass. Moreover, although the tensile elongation of the obtained molded product was high, the fracture toughness value was low and the tensile elastic modulus was low, which was not preferable.

Comparative Example 2
In Example 2, a vinyl chloride polymer (manufactured by Taiyo PVC Co., Ltd .: TH-1000) was used as 300 g, and a vinyl acetate-ethylene copolymer (manufactured by Tosoh Corporation: Petrocene 291R) was not added at all. In the same manner as in Example 2, a vinyl chloride polymer composition was prepared.
The content of montmorillonite determined from the ash content of the obtained molded product is 0.50% by mass, and montmorillonite has an average layer thickness of 160 μm and an average aspect ratio of 2.1, and is dispersed in an aggregated state. It was. Although the obtained molded article had high tensile modulus and tensile elongation, the fracture toughness value was low, which was not preferable.

Comparative Example 3
In Example 2, 300 g of a vinyl chloride polymer (manufactured by Taiyo PVC Co., Ltd .: TH-1000) was used, and chlorinated in the same manner as in Example 2 without adding montmorillonite (Kunimine Industry Co., Ltd .: Kunipia F). A vinyl polymer composition was prepared.
The content of montmorillonite determined from the ash content of the obtained molded product was 0% by mass, but the vinyl acetate-ethylene copolymer was dispersed with an average diameter of 360 nm.
However, although the tensile elongation of the obtained molded product was high, the fracture toughness value was low and the tensile elastic modulus was low, which was not preferable.

Comparative Example 4
In Example 2, the vinyl acetate-ethylene copolymer was changed to polyethylene having a vinyl acetate content of 0% by mass and an ethylene content of 100% by mass (trade name: Nipolon L, manufactured by Tosoh Corporation). A vinyl chloride polymer composition was prepared in the same manner as in Example 2 except for the above.
In the obtained molded product, polyethylene was dispersed with an average diameter of 820 nm. On the other hand, the content of montmorillonite determined from the ash content of the obtained molded product is 0.49% by mass, and the montmorillonite has an average layer thickness of 72 μm, an average aspect ratio of 3.2, and is agglomerated. It was dispersed and was not dispersed inside the polyethylene particles.
Although the tensile modulus and tensile elongation of the obtained molded product were both high, the fracture toughness value was low, which was not preferable.

Comparative Example 5
In Example 2, a vinyl acetate-ethylene copolymer was made of polyvinyl acetate having a vinyl acetate content of 100% by mass and an ethylene content of 0% by mass (manufactured by Nippon Synthetic Chemical Co., Ltd .: trade name: Gosenil). A vinyl chloride polymer composition was prepared in the same manner as in Example 2 except that the composition was changed.
The content of montmorillonite determined from the ash content of the obtained molded product is 0.50% by mass, the montmorillonite is dispersed with an average layer thickness of 80 nm, an average aspect ratio of 5.0, The polyvinyl acetate particles were encapsulated and dispersed inside, but the polyvinyl acetate itself was aggregated and dispersed to an average diameter of 15 μm in the obtained molded product.
Although the tensile modulus and tensile elongation of the obtained molded product were both high, the fracture toughness value was low, which was not preferable.

Comparative Example 6
In Example 2, except that the vinyl chloride polymer was changed to a vinyl chloride polymer (manufactured by Taiyo PVC Co., Ltd .: trade name: TH-500) produced by a suspension polymerization method with an average degree of polymerization of 510. A vinyl chloride polymer composition was prepared in the same manner as in Example 2.

  The content of montmorillonite determined from the ash content of the obtained molded product is 0.49% by mass, the montmorillonite is dispersed with an average layer thickness of 15 nm and an average aspect ratio of 30, and A part of the particles were dispersed inside the vinyl acetate-ethylene copolymer particles dispersed with an average diameter of 560 nm. However, it was not preferable because the obtained molded article had low tensile elastic modulus, tensile elongation, and fracture toughness.

Claims (9)

In a vinyl chloride polymer composition obtained by dispersing a layered swellable silicate and a vinyl acetate-ethylene copolymer in a vinyl chloride polymer,
(A) The vinyl chloride polymer has an average degree of polymerization of 600 or more,
(B) The layered swellable silicate dispersed in the composition has an average layer thickness of 0.5 to 100 nm as measured with an electron microscope and an average aspect ratio (ratio of layer length to layer thickness) of 5 or more. ,
(C) The vinyl acetate-ethylene copolymer dispersed in the composition has a particle shape with an average diameter of 10 to 1000 nm measured with an electron microscope, and
(D) A vinyl chloride polymer composition characterized in that a part or all of the layered swellable silicate has a form dispersed in the vinyl acetate-ethylene copolymer particles. The vinyl chloride polymer composition according to claim 1, wherein the vinyl acetate-ethylene copolymer contains 2 to 60% by mass of vinyl acetate in a mass ratio. The vinyl chloride heavy polymer according to claim 1 or 2, wherein the vinyl acetate-ethylene copolymer contains 1 to 40% by mass of vinyl alcohol by mass saponification of vinyl acetate. Combined composition. 4. The vinyl chloride polymer composition according to claim 2, wherein the vinyl acetate-ethylene copolymer is modified with maleic acid. The content ratio of the layered swellable silicate and the vinyl acetate-ethylene copolymer in the composition is 80:20 to 20:80 in mass ratio. The vinyl chloride polymer composition described. The layered swellable silicate contains 0.05 to 10% by mass of the composition as a residue when the composition is completely burned at 950 ° C. The vinyl chloride polymer composition described. The vinyl chloride polymer composition according to any one of claims 1 to 6, wherein a fracture toughness value measured according to ASTM D5045-99 is 3.1 MPa · m ^1/2 or more. A molded article obtained by molding the vinyl chloride polymer composition according to any one of claims 1 to 7. The molded article according to claim 8, wherein the molded article is a pipe.