JP6849579B2 - Vinyl chloride resin composition for paste - Google Patents

Description

The present invention is a vinyl chloride-based paste having excellent thermal stability and transparency when used as a flooring material, wallpaper, foam sheet, or other vinyl chloride-based resin molded product (hereinafter referred to as "PVC molded product"). It relates to a resin composition (hereinafter, referred to as "paste PVC").

Paste PVC is generally processed as a vinyl chloride-based plastisol (hereinafter referred to as "PVC plastisol") by kneading with a compounding agent such as a plasticizer, a stabilizer, and a foaming agent, and varies depending on various processing methods. A PVC molded product can be obtained. Among them, building materials such as wallpaper, flooring and foam sheets are one of the main uses of paste PVC.

As a general method for producing PVC paste, vinyl chloride for paste containing a polymer having an average width of 0.1 to 10 μm of secondary particles using a vinyl chloride-based monomer, a polymerization initiator, an emulsifier, water, or the like is first used. A method is used in which a based resin latex (hereinafter referred to as "PVC latex") is produced, and then the vinyl chloride latex is spray-dried using a spray dryer to obtain a paste vinyl chloride.

On the other hand, hydrotalcite is a layered double hydroxide containing a divalent metal and a basic carbonate of a trivalent metal as main components. Hydrotalcite has a high anion exchange ability and is widely used as a stabilizer for vinyl chloride resins, which is highly safe for living organisms.

Conventionally, various proposals have been made to add hydrotalcite at the time of production in order to improve the thermal stability of paste PVC. For example, Patent Document 1 proposes a vinyl chloride-based polymer composition having improved thermal stability and a low viscosity paste dispersion. Specifically, in a composition prepared by blending 0.05 to 5 parts by weight of hydrotalcites with respect to 100 parts by weight of a vinyl chloride polymer that can be pasted, the general formula Mg _{1 is used as the hydrotalcites. −x} Al _x (OH) ₂ (CO ₃ ) _{x / 2} · mH ₂ O (in the formula, m is a number satisfying 0 ≦ m <0.6 and x is a number satisfying 0 <x ≦ 0.32. A vinyl chloride-based polymer composition characterized by using hydrotalcites represented by.) Has been proposed. It is said that the hydrotalcites to be blended are particularly preferably those having a range of x of 0.30 ≦ x ≦ 0.32, a BET specific surface area of 30 m ² / g or less, and being treated with decrystallized water.

Patent Document 2 proposes a method for producing a vinyl chloride-based polymer composition for the purpose of improving thermal stability and water absorption and whitening property. Specifically, a vinyl chloride-based polymer composition capable of forming a paste obtained by emulsion polymerization or fine suspension polymerization of vinyl chloride alone or a mixture of vinyl chloride and another monomer copolymerizable therewith is prepared. In the method of producing, as a means for containing the hydrotalcites, the hydrotalcites are added in the form of an aqueous slurry in which the hydrotalcites are dispersed in deionized water at an arbitrary time before the start of the polymerization, during the polymerization or after the completion of the polymerization reaction. A method for producing a vinyl chloride-based polymer composition, which is characterized by using the above-mentioned method, is disclosed.

In Patent Document 3, a vinyl chloride resin composition for paste that can prevent bleeding to the surface when made into a vinyl chloride molded product and can give a plastisol having good adhesion between layers at the time of lamination, joining, etc. Proposed. Specifically, a vinyl chloride resin obtained by emulsion polymerization or fine suspension polymerization of a vinyl chloride monomer is provided with 0.05 to 1 part by weight of hydrotalcite and an alkylene group per 100 parts by weight of the resin. A vinyl chloride resin composition for paste containing 0.1 to 1 part by weight of a polyalkylene oxide having 2 to 4 carbon atoms, a plastisol obtained from the composition, and a laminate based on the same are disclosed. In addition, as a method of adding hydrotalcite, when it is added to latex, the fine powdered hydrotalcite may not be uniformly dispersed in the latex (water) and may partially agglomerate. It is said that it is better to add it as a slurry dispersed in water.

As described above, various proposals have been made for improving the thermal stability of paste PVC using hydrotalcite, but there is still room for improvement in the thermal stability. In addition, there is a problem that the transparency of the PVC molded product using the paste PVC is lowered by blending hydrotalcite.

Japanese Patent Application Laid-Open No. 2-123147 Japanese Patent Application Laid-Open No. 2-110108 Japanese Patent Application Laid-Open No. 9-77943

An object of the present invention is to provide a paste PVC having excellent thermal stability and transparency when it is used as a flooring material, wallpaper, foam sheet, or other PVC molded product. More specifically, in the process of manufacturing the paste PVC, it is possible to prevent the thermal deterioration of the paste PVC during spray drying, improve the thermal stability of the PVC molded product, and compare with the case where the conventional hydrotalcite is used. This is to improve the transparency of the PVC molded product.

The present inventors synthesize hydrotalcite having a smaller primary particle size and better dispersibility than the conventional one, and add it in a suspension state at the time of polymerization of the vinyl chloride resin to stabilize the molded product thermally. It has been found that a paste PVC having high properties and transparency can be produced. Furthermore, it has been found that by adding the hydrotalcite before spray drying, the thermal stability of the molded product becomes higher than when it is added after spray drying.

That is, the present invention provides a paste PVC that solves the above problems. Specifically, the composition of a vinyl chloride resin for paste containing 0.05 parts by weight or more and less than 5 parts by weight of hydrotalcite represented by the following (formula 1) with respect to 100 parts by weight of the vinyl chloride resin for paste. It is a vinyl chloride resin composition for paste, wherein the hydrotalcite in the vinyl chloride resin composition for paste satisfies the following (A) and (B).
^{_{(M 2+) 1-X (}} M 3+) X (OH) 2 (A n-) X / n · mH 2 O ( Equation 1)
(Wherein in ^{M 2+} is a divalent metal of at least one or ^{more, M 3+} is at least one kind of trivalent ^{metal, A n-represents} n-valent anion, n is an integer of 1 to 6, respectively, x And m are in the range of 0.17 ≦ x ≦ 0.36 and 0 ≦ m ≦ 10, respectively).
(A) The average width of the primary particles in the resin by the SEM method is 5 nm or more and 200 nm or less;
(B) The monodispersity in the resin represented by the following formula is 50% or more;
Monodispersity in resin (%) = (average width of primary particles in resin by SEM method / average width of secondary particles in resin by SEM method) × 100

The present invention includes the method for producing the above-mentioned paste PVC, the above-mentioned vinyl chloride plastisol containing the paste vinyl chloride and a plasticizer, and a vinyl chloride molded product composed of the above-mentioned vinyl chloride plastisol.

The PVC molded product using the paste PVC of the present invention has higher thermal stability and transparency than the conventional ones. The vinyl chloride plastisol containing the paste PVC of the present invention is suitably used for molding of wallpaper, tile carpets, gloves, automobile undercoats and the like.

It is a schematic diagram explaining the width of the primary particle of hydrotalcite used in this invention. It is a schematic diagram explaining the width of the secondary particle of hydrotalcite used in this invention.

Hereinafter, the present invention will be specifically described.

<Paste PVC>
The composition of the paste PVC of the present invention, the average particle size, the vinyl chloride-based resin for paste contained, and the hydrotalcite contained are as follows.

(Constitution)
The paste PVC of the present invention contains 0.05 parts by weight or more and less than 5 parts by weight of hydrotalcite with respect to 100 parts by weight of the vinyl chloride resin for paste. The lower limit of the content of hydrotalcite is more preferably 0.1 part by weight, still more preferably 0.2 part by weight, based on 100 parts by weight of the vinyl chloride resin for paste. The upper limit of the content of hydrotalcite is more preferably 4 parts by weight, still more preferably 3 parts by weight, based on 100 parts by weight of the vinyl chloride resin for paste. The paste PVC of the present invention is a vinyl chloride-based paste such as a polymerization initiator, an emulsifier, an emulsifying aid, a buffer, a higher alcohol, a higher fatty acid, a higher fatty acid ester, a dispersion aid such as chlorinated paraffin, and a degree of polymerization adjusting agent. It may contain a substance generally added in the polymerization of the resin.

(Average particle size)
The paste PVC of the present invention has an average particle size (D50) of 10 to 200 μm in the dry particle size measurement method. The upper limit of the average particle size is preferably 190 μm, more preferably 180 μm, and even more preferably 170 μm. The lower limit of the average particle size is preferably 15 μm, more preferably 20 μm, and even more preferably 25 μm. If the average particle size is smaller than 10 μm, the viscosity becomes high when the vinyl chloride plastisol is used, and the handleability deteriorates, which is not preferable. If the average particle size is larger than 200 μm, the dispersibility of the paste PVC in the plasticizer becomes poor when the vinyl chloride plastisol is used, which is not preferable.

(Vinyl chloride resin for paste)
The vinyl chloride-based resin for paste contained in the paste vinyl chloride of the present invention is polyvinyl chloride or a copolymer of a vinyl chloride monomer and a copolymerizable monomer thereof. Examples of the monomer copolymerizable with vinyl chloride include vinylidene chloride, ethylene, propylene, acrylonitrile, vinyl acetate, maleic acid, acrylic acid, and acrylic acid ester, but the present invention is not limited to this.

The average degree of polymerization of the paste PVC of the present invention is preferably in the range of 400 to 4000. When the degree of polymerization is less than 400, the thermal stability of the polymer is poor and it tends to be colored yellow. In addition, the product strength may decrease. When a polymer having a degree of polymerization greater than 4000 is used, the foamability and moldability (gelling property) are adversely affected, so that the productivity and designability tend to deteriorate.

(Chemical formula of hydrotalcite)
The hydrotalcite of the present invention is represented by the following formula (1).
^{_{(M 2+) 1-X (}} M 3+) X (OH) 2 (A n-) X / n · mH 2 O (1)
(Wherein in ^{M 2+} is a divalent metal of at least one or ^{more, M 3+} is at least one kind of trivalent ^{metal, A n-represents} n-valent anion, n is an integer of 1 to 6, respectively, x And m are in the range of 0.17 ≦ x ≦ 0.36 and 0 ≦ m ≦ 10, respectively).

(Type of hydrotalcite metal)
In the hydrotalcite represented by the formula (1), M ²⁺ is at least one kind of divalent metal, and M ³⁺ is at least one kind of trivalent metal. The preferred divalent metal is at least one selected from the group consisting of Mg and Zn, and the preferred trivalent metal is Al. This is because it is highly safe for living organisms, and the particles are white and versatile.

(X range of hydrotalcite)
In the hydrotalcite represented by the formula (1), the range of x is 0.17 ≦ x ≦ 0.36. A more preferable upper limit of x is 0.34. A more preferable lower limit of x is 0.19. If x exceeds 0.36, boehmite is by-produced, and conversely, if it is less than 0.17, magnesium hydroxide is by-produced, and in both cases, the transparency is lowered when the vinyl chloride resin composition is prepared.

(M range of hydrotalcite)
In the hydrotalcite represented by the formula (1), the range of m is 0 ≦ m ≦ 10. A more preferable upper limit of m is 6.

(Type of interlayer anion of hydrotalcite)
In hydrotalcite represented by the formula (1) ^{represents A n-} is an n-valent anion, n is an integer of 1 to 6, respectively, preferred ^{A n-} is _CO ^{3 2-} and ClO ₄ ^- is selected from 1 More than a seed.

(Lattice strain in the <003> direction of hydrotalcite)
In the hydrotalcite of the present invention, the lattice strain in the <003> direction in the X-ray diffraction method is 3 × 10 ^-3 or less, preferably 2.5 × 10 ^-3 or less, and more preferably 2 × 10 ^-3 or less. Is. If the lattice strain in the <003> direction ^{is larger than 3 × 10 -3} , the primary particles agglomerate in the suspension and the resin, and the thermal stability and transparency of the PVC resin composition deteriorate.

(BET specific surface area of hydrotalcite)
In the hydrotalcite of the present invention, the BET method specific surface area is 20 to 600 m ² / g. The more preferable upper limit of the BET method specific surface area is 500 m ² / g, and more preferably 400 m ² / g. The more preferable lower limit of the BET method specific surface area is 30 m ² / g, and more preferably 40 m ² / g. If the specific surface area of the BET method ^{is less than 20 m 2} / g, the reactivity with free halogen and the dispersion of primary particles are not sufficient. On the other hand, ^{if it is larger than 600 m 2} / g, the vinyl chloride resin composition is easily colored, which is not preferable.

(Definition of primary particles of hydrotalcite)
A primary particle is a particle with a clear boundary that cannot be geometrically divided any further. FIG. 1 is a schematic view illustrating _{the lateral width (W 1} ) of the primary particles used in the present invention. As shown in FIG. 1, it defines the width W ₁ of the primary particles. That is, the major axis of the particles when the primary particles have a hexagonal plate-like plate surface is "width W _{1 of the} primary particles".

(Definition of secondary particles of hydrotalcite)
Secondary particles are particles in which a plurality of primary particles are aggregated to form an agglomerate. FIG. 2 is a schematic diagram illustrating the _{width (W 2} ) of the secondary particles and the secondary particles used in the present invention. As shown in FIG. 2, the width W ₂ of the secondary particles is defined. That is, the diameter of the sphere when it is considered that the secondary particles are wrapped in the sphere is "the width W _{2 of the} secondary particles".

(Average width of primary particles in hydrotalcite resin)
In the hydrotalcite of the present invention, the average width of the primary particles in the resin by the SEM method is 5 to 200 nm. The upper limit of the average width of the primary particles in the resin is preferably 180 nm, more preferably 150 nm, still more preferably 120 nm, still more preferably 100 nm, and most preferably 60 nm. If the average width of the primary particles is larger than 200 nm, the transparency of the vinyl chloride resin composition deteriorates. The average width of the primary particles is obtained from the arithmetic mean of the measured values of the widths of any 100 primary particles in the SEM photograph by the SEM method.

(Monodispersity of hydrotalcite in resin)
In the hydrotalcite of the present invention, the monodispersity in the resin represented by the following formula is 50% or more, more preferably 60% or more, still more preferably 80% or more. If the monodispersity of hydrotalcite in the resin is less than 50%, the thermal stability and transparency of the vinyl chloride resin composition deteriorate. The width of the primary particles in the resin and the width of the secondary particles in the resin are determined by the arithmetic mean of the measured values of the widths of any 100 primary particles and secondary particles in the SEM photograph by the SEM method. Ask for each.
Monodispersity in resin (%) = (average width of primary particles in resin by SEM method / average width of secondary particles in resin by SEM method) × 100

<PVC plastisol>
(Constitution)
The vinyl chloride plastisol of the present invention contains the paste vinyl chloride of the present invention and various additives such as plasticizers, fillers and thickeners.

(Plasticizer)
Plasticizers include phthalates such as DOP (dioctylphthalate) and DINP (diisononylphthalate), which are general-purpose plasticizers, as well as trimellitic acid esters, adipic acid esters, azelaic acid esters, and sebatic acid. Examples thereof include ester-based, phosphoric acid ester-based, polyester-based, epoxy-based, fatty acid ester-based, and phthalate acid ester-based plasticizers. From the viewpoint of the performance of the final product, the amount of the plasticizer to be blended is preferably 10 to 150 parts, more preferably 20 to 140 parts with respect to 100 parts by weight of the paste PVC.

(Thickening agent)
In addition to the above components, a slimming agent may be used in the vinyl chloride plastisol of the present invention. Examples of the thickener include, but are not limited to, hydrocarbon compounds such as alkylbenzene, mineral spirit, and paraffin, higher alcohol fatty acid esters, sorbitan fatty acid esters, and glycerin fatty acid esters.

The vinyl chloride plastisol of the present invention may contain additives such as fillers, stabilizers, lubricants, antioxidants, ultraviolet absorbers, foaming agents, flame retardants, and colorants.

<PVC molded product>
The present invention includes a vinyl chloride molded product made of the vinyl chloride plastisol of the present invention.

<Manufacturing method of paste PVC>
The paste PVC of the present invention can be produced by a production method including the following (step 1) to (step 6).
(Step 1) A raw material preparation step for preparing a water-soluble composite metal salt aqueous solution and an alkali metal hydroxide aqueous solution. However, the aqueous solution of the water-soluble composite metal salt contains a divalent metal salt, a trivalent metal salt, and a monovalent organic acid and / or an organic acid salt that forms a complex with the trivalent metal.
(Step 2) The water-soluble composite metal salt aqueous solution and the alkali metal hydroxide aqueous solution prepared in (Step 1) are continuously reacted at a reaction temperature of 0 to 60 ° C. and a reaction pH of 8.5 to 11.5 to obtain hydrotalcite. Reaction step to obtain a suspension containing.
(Step 3) A washing step in which the suspension containing hydrotalcite obtained in (Step 2) is dehydrated, washed with water, and suspended in an aqueous solvent.
(Step 4) A aging step in which the suspension containing the washed hydrotalcite obtained in (Step 3) is stirred and held at 0 to 100 ° C. for 1 to 60 hours.
(Step 5) A polymerization step of obtaining a vinyl chloride resin latex by polymerizing a vinyl chloride monomer alone or a mixture of a vinyl chloride monomer and another monomer copolymerizable with vinyl chloride. However, the suspension containing hydrotalcite prepared in (Step 4) is polymerized with respect to 100 parts by weight of the vinyl chloride resin in an amount of 0.05 parts by weight or more and less than 5 parts by weight in terms of the solid content of hydrotalcite. It is added at any time before, during polymerization, and after completion of polymerization.
(Step 6) A drying step of spray-drying the vinyl chloride resin latex obtained in (Step 5).

(Step 1: Raw material preparation process)
The raw materials for hydrotalcite are divalent metal salts, trivalent metal salts, monovalent organic acids and / or organic acid salts that form a complex with trivalent metals, and alkali metal hydroxide salts. Examples of the divalent metal salt include water-soluble divalent metal salts such as magnesium chloride, magnesium bromide, magnesium nitrate, magnesium acetate, zinc chloride, zinc bromide, zinc nitrate, zinc acetate and the like, but this is not the case. Absent. In order to prevent agglomeration of primary particles, a divalent metal salt containing a monovalent anion is preferably used. It is also possible to combine two or more kinds of divalent metal salts. Preferably, magnesium chloride and / or zinc chloride is used. Examples of the trivalent metal salt include, but are not limited to, water-soluble trivalent metal salts such as aluminum chloride, aluminum bromide, aluminum nitrate, and aluminum acetate. In order to prevent agglomeration of primary particles, a trivalent metal salt containing a monovalent anion is preferably used. It is also possible to combine two or more trivalent metal salts. Aluminum chloride is preferably used.

Generally, the precipitation pH of a trivalent metal ion as a hydroxide is lower than the precipitation pH of a divalent metal. Therefore, even if the pH at the time of reaction is kept constant by a pH adjuster, trivalent ions are first precipitated as hydroxides. Due to the difference in precipitation pH between the divalent metal and the trivalent metal, crystal strain is generated and hydrotalcite primary particles are agglutinated.

Therefore, by using a monovalent organic acid and / or an organic acid salt as a complex-forming agent and forming a complex with a trivalent metal, the precipitation pH of the trivalent metal ion as a hydroxide is increased, and the divalent metal By approaching the precipitation pH, hydrotalcite with less crystal strain can be obtained. The complex-forming agent also has the effect of suppressing the crystal growth of the primary particles of hydrotalcite due to the steric hindrance effect of the molecule. Examples of monovalent organic acids and / or organic acid salts that form a complex with a trivalent metal include lactic acid, sodium lactate, formic acid, sodium formate, acetic acid, sodium acetate, propionic acid and sodium propionate. This is not the case. It is also possible to combine two or more kinds of organic acids and organic acid salts. Preferably, lactic acid, sodium lactate, acetic acid and sodium acetate are used. Examples of the alkali metal hydroxide salt include, but are not limited to, sodium hydroxide and potassium hydroxide.

A water-soluble composite metal salt aqueous solution is prepared by dissolving a divalent metal salt, a trivalent metal salt, and a monovalent organic acid and / or an organic acid salt forming a complex with the trivalent metal in an aqueous solvent. The concentration of the divalent metal in the aqueous solution of the water-soluble composite metal salt is 0.01 to 2 mol / L, preferably 0.1 to 1.5 mol / L. The concentration of the trivalent metal is 0.01 to 2 mol / L, preferably 0.1 to 1.5 mol / L. The concentration of the alkali metal hydroxide is 0.01 to 4 mol / L, preferably 0.1 to 2 mol / L. The ratio of the divalent metal to the trivalent metal is 1.78 ≤ M ²⁺ / M ³⁺ ≤ 4.88, preferably 1.94 ≤ M ²⁺ / M ³⁺ ≤ 4.26. The amount of the monovalent organic acid and / or the organic acid salt added to form a complex with the trivalent metal is 0.1 to 2.2 equivalents, preferably 0.3 to 2 equivalents, relative to the trivalent metal. is there. If it is less than 0.1 equivalent, the primary particles of hydrotalcite become larger than 200 nm, which is not preferable. If the amount is more than 2.2 equivalents, anions derived from the complex-forming agent enter between the layers of the hydrotalcite, and the suspension gels due to the swelling action, which is not preferable.

(Step 2: Reaction step)
The hydrotalcite of the present invention is produced by a continuous reaction. Since the ion concentration and pH in the solution can be kept uniform as compared with the batch reaction, hydrotalcite with less lattice strain can be produced, and the production efficiency is higher than that of the batch reaction.

The concentration at the time of reaction is 0.1 to 300 g / L in terms of hydrotalcite, preferably 0.5 to 250 g / L, and more preferably 1 to 200 g / L. If the concentration at the time of the reaction is lower than 0.1 g / L, the productivity is low, and if it is higher than 300 g / L, the primary particles are aggregated, which is not preferable. The temperature during the reaction is 0 to 60 ° C, preferably 10 to 50 ° C, and more preferably 20 to 40 ° C. If the temperature during the reaction is lower than 0 ° C., the suspension freezes, which is not preferable, and if the temperature is higher than 60 ° C., the primary particles become larger than 200 nm, which is not preferable. The pH at the time of reaction is 8.5 to 11.5, preferably 8.8 to 11.0, and more preferably 9.1 to 10.5. If the pH at the time of reaction is lower than 8.5, the lattice strain of hydrotalcite becomes large and the monodispersity in suspension and resin decreases, which is not preferable. If the pH is higher than 11.5, after aging. It is not preferable because the primary particles of hydrotalcite become larger than 200 nm.

(Step 3: Cleaning step)
The suspension containing hydrotalcite prepared in the above (step 2) is dehydrated, washed with deionized water having a weight 20 to 30 times that of hydrotalcite, and resuspended in deionized water. By going through this step, salts such as sodium can be removed, and agglomeration of primary particles during the aging step can be prevented.

In the washing step, ion exchange can be carried out with any anion after dehydration and before washing with water. There are two methods of ion exchange. The first is a method in which the suspension containing hydrotalcite after the reaction is dehydrated to form a cake, dispersed in ion-exchanged water, an anion-containing aqueous solution is added, and the suspension is stirred and held. At this time, the equivalent of the anion is 1 to 5 equivalents, more preferably 1.5 to 3 equivalents, relative to hydrotalcite. The stirring and holding temperature is preferably 30 to 90 ° C, more preferably 50 to 80 ° C. The concentration of hydrotalcite is preferably 0.1 to 300 g / L, more preferably 0.5 to 250 g / L, and even more preferably 1 to 200 g / L in terms of hydrotalcite.

The second method of ion exchange is a method in which the suspension containing hydrotalcite after the reaction is dehydrated to form a cake, and then an anion-containing aqueous solution is directly added. At this time, the amount of anion added is 1 to 5 equivalents, preferably 1.5 to 3 equivalents, relative to hydrotalcite.

(Step 4: Aging step)
The suspension containing hydrotalcite prepared in the above (step 3) is stirred and held at 0 to 100 ° C. for 1 to 60 hours. By going through this step, the aggregation of the primary particles is relaxed, and a suspension in which the primary particles are sufficiently dispersed can be obtained. If the aging time is less than 1 hour, it is not enough time to relax the aggregation of the primary particles. Aging for more than 60 hours does not make sense because there is no change in the aggregated state. The preferred aging time is 2 to 30 hours, more preferably 4 to 24 hours. If the aging temperature is higher than 100 ° C., the primary particles will be larger than 200 nm, which is not preferable. If the aging temperature is less than 0 ° C., the suspension freezes, which is not preferable. The preferred aging temperature is 20-90 ° C, more preferably 40-80 ° C. The concentration at the time of aging is 0.1 to 300 g / L in terms of hydrotalcite, preferably 0.5 to 250 g / L, and more preferably 1 to 200 g / L. If the concentration at the time of aging is lower than 0.1 g / L, the productivity is low, and if it is higher than 300 g / L, the primary particles are aggregated, which is not preferable.

(Step 5: Polymerization step)
Vinyl chloride alone or a mixture of vinyl chloride and a copolymerizable monomer thereof is polymerized by an emulsion polymerization method or a fine suspension polymerization method. Examples of the monomer copolymerizable with vinyl chloride include vinylidene chloride, ethylene, propylene, acrylonitrile, vinyl acetate, maleic acid, acrylic acid, and acrylic acid ester, but the present invention is not limited to this. The vinyl chloride-based monomer is placed in an aqueous medium in the presence of an emulsifier and a water-soluble polymerization initiator, and the fine suspension polymerization is carried out by placing the vinyl chloride-based monomer in an aqueous medium in the presence of an emulsifier and an oil-soluble polymerization initiator. It is carried out by homogenizing underneath and polymerizing.

Examples of emulsifiers used in the emulsification polymerization method include higher alcohol sulfate ester salts (alkali metal salts, ammonium salts), alkylbenzene sulfonates (alkali metal salts, ammonium salts), and higher fatty acid salts (alkali metal salts, ammonium salts). Other anionic surfactants, nonionic surfactants, and / or cationic surfactants may be mentioned. One type of these surfactants may be used, or two or more types may be used in combination. The amount of the emulsifier used is in the range of 0.1 to 3% by weight, more preferably 0.3 to 1% by weight, based on the vinyl chloride-based monomer, but is not particularly limited.

These emulsifiers may be additionally used for adjusting the foamability during processing, and at this time, they may be added separately from the polymerization emulsifier after the completion of the polymerization reaction. The polymerization initiator is generally used in each polymerization method of the vinyl chloride-based monomer, and is not particularly limited. For example, as the polymerization initiator used in the emulsion polymerization method, a water-soluble peroxide such as persulfite (sodium salt, potassium salt, ammonium salt), hydrogen peroxide, or these water-soluble peroxides can be used. Examples thereof include a water-soluble redox-based initiator composed in combination with a water-soluble reducing agent (for example, sodium sulfite, sodium pyrosulfite, sodium hydrogen peroxide, ascorbic acid, sodium formaldehyde sulfoxylate, etc.).

Further, as the polymerization initiator used in the fine suspension polymerization method, monomer-soluble such as azobisisobutyronitrile, azobis (2,4-dimethylvaleronitrile), lauroyl peroxide, t-butylperoxypivalate and the like ( An example thereof is an oil-soluble) initiator or a redox-based initiator composed of a combination of these oil-soluble initiators and the above-mentioned water-soluble reducing agent.

These polymerization initiators can be used alone or in combination of two or more. The amount of the polymerization initiator used varies depending on the type of the initiator, the polymerization temperature, the desired reaction time, and the like, but is generally 0.01 to 1% by weight based on the total amount of the vinyl chloride-based monomer. Further, in the polymerization of the vinyl chloride-based monomer, various polymerizations such as a degree of polymerization adjusting agent (chain transfer agent, cross-linking agent), an antioxidant, a pH adjusting agent, and an activator of a redox-based initiator are required. Auxiliary agents can be added as appropriate, and the types and amounts of each of these components may be those generally used in the conventional polymerization of vinyl chloride-based monomers.

Examples of the degree of polymerization adjusting agent used for the polymerization of vinyl chloride-based monomers include chain transfer agents such as trichloroethylene, carbon tetrachloride, 2-mercaptoethanol, and octyl mercaptan, diallyl phthalate, triaryl isocyanurate, and ethylene glycol. Cross-linking agents such as diacrylate and trimethylolpropane trimethacrylate are exemplified.

The hydrotalcite suspension prepared in the above (step 4) after the aging treatment is added at an arbitrary time before the start of the polymerization, during the polymerization, or after the completion of the polymerization reaction. It is preferable to add the particles after the completion of the polymerization so as not to affect the dispersion stability during the polymerization and the particle formation. By adding the hydrotalcite suspension after aging, the primary particles are sufficiently dispersed in the paste PVC, and the thermal stability and transparency of the PVC molded product are remarkably improved. Further, by adding hydrotalcite before spray drying, it is possible to prevent thermal deterioration of the paste PVC during spray drying.

The amount of hydrotalcite added is 0.05 parts by weight or more and less than 5 parts by weight with respect to 100 parts by weight of the vinyl chloride resin. The lower limit of the content of hydrotalcite is more preferably 0.1 part by weight, still more preferably 0.2 part by weight, based on 100 parts by weight of the vinyl chloride resin for paste. The upper limit of the content of hydrotalcite is more preferably 4 parts by weight, still more preferably 3 parts by weight, based on 100 parts by weight of the vinyl chloride resin for paste.

(Step 6: Drying step)
The vinyl chloride latex produced in (Step 5) is dried by spray drying. The dryer used for spray drying is not particularly limited. The drying air inlet temperature and the drying air outlet temperature are not particularly limited, but the drying air inlet temperature is preferably 80 to 400 ° C., and the drying air outlet temperature is preferably 50 to 200 ° C. The drying air inlet temperature is more preferably 200 to 350 ° C., and the drying air outlet temperature is more preferably 80 to 130 ° C. By spray drying, granular paste PVC having an average particle size of 10 to 200 μm in the dry particle size measurement method can be obtained. If the paste PVC after spray drying contains water, it may be additionally dried with hot air.

In order to reduce the coarse particles in the paste PVC, it is preferable to remove the coarse particles with a sieve from the obtained paste PVC. The sieve may be a generally used sieve, and examples thereof include a vibrating sieve, an ultrasonic vibrating sieve, a three-dimensional vibrating sieve, a net-fixed wind classifier, and the like. It is possible to use a combination of different plurality.

Further, the coarse particles in the latex may be removed before the vinyl chloride latex is spray-dried. As a device for removing coarse particles, for example, a generally used device such as a wet vibrating sieve, a wet centrifuge, or a liquid cyclone can be used, but from the viewpoint of coarse grain removal efficiency and processing amount, the wet type can be used. A vibrating sieve is preferred.

Further, in order to increase the drying efficiency, the vinyl chloride latex may be concentrated and then spray-dried. As the concentrator, known ones such as an ultrafiltration membrane, a vacuum evaporator, and a thin film type evaporator can be used alone or in combination of two or more.

A liquid binder can also be added prior to spray drying of the PVC latex. Here, the liquid binder is for improving the dispersibility of the obtained granules in the plasticizer, and examples thereof include a polyhydric alcohol and / or an ether compound of the polyhydric alcohol. For example, ethylene glycol diether compounds such as ethylene glycol, ethylene glycol dibenzyl ether, ethylene glycol dibutyl ether, ethylene glycol diethyl ether, and ethylene glycol dimethyl ether, ethylene glycol monobenzyl ether, ethylene glycol mono n-butyl ether, and ethylene glycol monoethyl. Examples thereof include monoether compounds such as ether and ethylene glycol monomethyl ether.

<Manufacturing method of PVC plastisol>
The vinyl chloride plastisol of the present invention is prepared by adding the above-mentioned plasticizer and other compounding agents as necessary to the paste PVC, and using a ribbon blender, a super mixer, a hovert mixer, a disper, a dissolver, etc., which are usually used for paste processing. Can be manufactured.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples. In the examples, each physical property was measured by the following method.

(A) The cross section of the paste PVC was polished using a cross-section polisher (IB-09010CP, manufactured by JEOL Ltd.) having an average width of the primary particles and secondary particles of hydrotalcite in the resin. Using a scanning electron microscope (SEM) (JSM-7600F, manufactured by JEOL Ltd.), observe the cross section of the resin after polishing, measure the width of the primary and secondary particles of any 100 crystals, and calculate the calculation. The average was taken as the average width of the primary particles and the secondary particles in the resin.

(B) Monodispersity of hydrotalcite in resin Calculated from the value of (A) above based on the following formula.
Monodispersity in resin (%) = (average width of primary particles in resin by SEM method / average width of secondary particles in resin by SEM method) × 100

(C) Crystal strain of hydrotalcite in the <003> direction The aqueous suspension containing hydrotalcite prepared in the above (step 4) was dehydrated, vacuum dried, and then pulverized to prepare a measurement sample.
Based on the relational expression of (Equation 2), plot (sinθ / λ) on the horizontal axis and (βcosθ / λ) on the vertical axis, and calculate the crystal particle size (g) from the reciprocal of the intercept and (1/2) for the gradient. The crystal strain (η) was obtained by multiplying.
(Βcosθ / λ) = (1 / g) + 2η × (sinθ / λ) (Equation 2)
(However, λ represents the wavelength of the X-ray used and is 1.542 Å for Cu-Kα rays. θ represents the Bragg angle and β represents the true half width (unit: radian).)
The above β was determined by the following method.
Using an X-ray diffractometer (Empylean, manufactured by PANalytical), the diffraction profiles of the (003) and (006) planes were measured using Cu-Kα rays generated under the conditions of 45 KV and 40 mA as the X-ray source. .. The measurement conditions are 10 ° / min at goniometer speed, the slit width is in the order of divergence slit, receiving slit, and scattering slit. For the (003) plane, 1 ° -0.3 mm-1 °, for the (006) plane. Was measured under the condition of 2 ° -0.3 mm-2 °. _{For the obtained profile, the width (B 0} ) at (1/2) of the height from the background to the diffraction peak was measured. From _{the relationship between the split widths (δ) of K α1} and K _α2 with respect to 2θ, δ with respect to 2θ of the (003) plane and the (006) plane was read. Next, B was obtained from the relationship between _{(δ / B 0} ) and (B / B ₀ ) based on the values of _{B 0 and δ.} Subsequently, for high-purity silicon (purity 99.999%), each diffraction profile was measured at a slit width (1/2) ° −0.3 mm − (1/2) ° to obtain a half width (b). .. This was plotted against 2θ to create a graph showing the relationship between b and 2θ. (B / β) was obtained from b corresponding to 2θ of the (003) plane and the (006) plane. Β was determined from the relationship between (b / B) and (β / B).

(D) BET Specific Surface Area of Hydrotalcite The aqueous suspension containing hydrotalcite prepared in the above (step 4) was dehydrated, vacuum dried, and then pulverized to prepare a measurement sample. The specific surface area of the sample after drying was measured by a gas adsorption method using a specific surface area measuring device (NOVA2000, manufactured by Yuasa Ionics).

(E) Quantification of Chemical Composition of Hydrotalcite The aqueous suspension containing hydrotalcite prepared in the above (step 4) was dehydrated, vacuum dried, and then pulverized to prepare a measurement sample. After the sample was heated and dissolved in nitric acid, Mg, Zn and Al were quantified by chelatometric titration, and Cl was quantified by Forhardt titration. CO ₃ is JIS. R. Based on 9101, it was quantified with an _{AGK type CO 2 simple precision quantifier.} Interlayer water was calculated from the weight loss using TG-DTA.

(F) Thermal Stability of PVC Mold The sample PVC plastisol was applied onto an aluminum foil so that the thickness after heating was 1 mm. The coating film was heat-treated at 195 ° C. for 5 minutes and then cut into a sheet having a length and width of 4 cm. The sheet was continuously heated at 195 ° C., taken out every 5 minutes of heating time, and the time until the sheet was colored red to dark brown was visually confirmed. The longer the time until coloring, the better the thermal stability.

(G) Transparency of PVC Mold The sample PVC plastisol was applied onto an aluminum foil so that the thickness after heating was 1 mm. The coating film was heat-treated at 195 ° C. for 5 minutes and then cut into a sheet having a length and width of 4 cm. Three sheets of the prepared sheets are stacked, placed in a mold having a thickness of 2 mm, sandwiched between stainless steel plates from above and below, and pressed with a press machine (ANSF-50HH / C, manufactured by Shinto Metal Industry Co., Ltd.) at 200 ° C. for 10 minutes at 100 MPa. , A test piece was prepared. The haze (cloudiness) of the prepared test piece was determined by JIS. K. Based on 7136, the transparency was evaluated by measuring with a haze meter (automatic haze meter TC-H3DP, manufactured by Tokyo Denshoku). The lower the haze, the better the transparency.

(Step 1: Raw material adjustment process)
Magnesium chloride hexahydrate (Wako Pure Chemical Industries, Ltd.) and aluminum chloride hexahydrate (Wako Pure Chemical Industries, Ltd.) were dissolved in deionized water to obtain an aqueous solution of magnesium 0.2 mol / L and aluminum 0.1 mol / L. To this aqueous solution, 1.75 equivalents of sodium lactate (Kishida Chemical) was added to aluminum to prepare a water-soluble composite metal salt aqueous solution. On the other hand, sodium hydroxide (Wako Pure Chemical Industries, Ltd.) was dissolved in deionized water to a concentration of 0.8 mol / L to prepare an aqueous alkali metal hydroxide solution.

(Step 2: Reaction step)
Set the flow rate of the water-soluble composite metal salt aqueous solution to 120 mL / min and the flow rate of the alkali metal hydroxide aqueous solution to 95 mL / min, and pour each into a columnar reaction vessel with an overflow capacity of 215 mL to continuously react. went. The suspension that overflowed from the reaction vessel as an overflow was collected, and the flow rate of the alkali metal hydroxide aqueous solution was adjusted so that the pH was 9.3 to 9.6. During the reaction, the temperature of the raw material and the reaction vessel was adjusted so that the reaction temperature was 25 ° C. During the reaction, a screw propeller having a diameter of 2.5 cm was used to stir at a rotation speed of 1000 rpm.

(Step 3: Cleaning step)
The suspension was dehydrated by suction filtration using a circular nutche and a suction filtration bottle to make a cake. Next, 1.5 equivalents of an aqueous sodium carbonate solution was poured into the cake with respect to the aluminum of hydrotalcite contained in the cake, and ion exchange was performed. Next, the cake was washed with water after ion exchange for the purpose of removing by-products such as salts and impurities such as residual sodium carbonate using deionized water 30 times by mass of hydrotalcite.

(Step 4: Aging step)
The cake after washing with water was resuspended in deionized water. Resuspension was carried out using a homomixer at a rotation speed of 4000 rpm for 20 minutes. Deionized water was poured into the resuspended suspension to adjust the concentration to 50 g / L. The concentration-adjusted suspension was kept at 60 ° C. in a constant temperature bath and aged for 24 hours to obtain a suspension of hydrotalcite A. Table 1 shows the production conditions of hydrotalcite A, and Table 2 shows the chemical composition of hydrotalcite A, the crystal strain in the <003> direction, and the specific surface area of the BET method.

(Step 5: Polymerization step)
After degassing by charging 90 kg of deionized water and 60 g of sodium pyrosulfite into a polymerizer having a volume of 200 liters equipped with a stirrer, 60 kg of vinyl chloride monomer was charged and a 0.2% potassium persulfate aqueous solution was added at a ratio of about 10 ml / min. The mixture was continuously added in 1 and polymerized at 50 ° C. to prepare a latex of a seed polymer having an average particle size of 0.48 μm.

Next, in the same 200 liter polymerizer with a stirrer, 80 kg of deionized water, 15 g of sodium lauryl sulfate, 90 g of ammonium persulfate, and 4.5 kg of the seed latex prepared above were charged as solids, degassed, and then vinyl chloride monomer 75. 5.5 kg was charged, 10 liters of a 0.4% ammonium persulfate aqueous solution and 6 liters of an ammonium myristate aqueous solution were continuously added, and polymerization was carried out at 47 ° C. When the reaction rate reached 12%, 100 g of a degree of polymerization modifier (diallyl phthalate) was press-fitted into the system. When the internal pressure of the polymerizer decreased from the saturated vapor pressure of the vinyl chloride monomer at 47 ° C. to 1 kg / cm ² , the unreacted monomer was released to the outside of the system to stop the reaction. The average degree of polymerization of the vinyl chloride resin was 2500.

The suspension of hydrotalcite after aging obtained in (Step 4) was added to the vinyl chloride resin latex obtained as described above as a solid content with respect to 100 parts by weight of the vinyl chloride resin in the latex under stirring. 0.5 parts by weight was added.

(Step 6: Drying step)
The vinyl chloride latex obtained in (Step 5) was spray-dried with a spray dryer by a nozzle method to obtain the paste PVC A of the present invention. The temperature in the drying chamber was set to be an inlet temperature of 250 ° C. and an outlet temperature of 90 ° C. Table 3 shows the average particle size of the paste PVC A, the average width of the primary particles in the hydrotalcite resin, the average width of the secondary particles in the resin, and the monodispersity in the resin.

In the aging step of Example 1, hydrotalcite was prepared in the same manner except that the aging temperature was set to 90 ° C. to obtain a suspension of hydrotalcite B. Subsequent steps were carried out in the same manner as in Example 1 to obtain the paste PVC B of the present invention. Table 1 shows the production conditions of hydrotalcite B, the chemical composition of hydrotalcite B, crystal strain in the <003> direction, and the specific surface area of the BET method in Table 2, the average particle size of paste PVC B, and the resin of hydrotalcite. Table 3 shows the average width of the primary particles in the resin, the average width of the secondary particles in the resin, and the monodispersity in the resin, respectively.

In the washing step of Example 1, instead of the sodium carbonate aqueous solution, 1.5 equivalents of sodium perchlorate aqueous solution was poured into the cake with respect to the aluminum of hydrotalcite contained in the cake, and ion exchange was performed. A sample was prepared in the same manner except for the above, and a suspension of hydrotalcite C was obtained. Subsequent steps were carried out in the same manner as in Example 1 to obtain the paste PVC C of the present invention. Table 1 shows the production conditions of hydrotalcite C, the chemical composition of hydrotalcite C, crystal strain in the <003> direction, and the specific surface area of the BET method in Table 2, the average particle size of paste PVC C, and the resin of hydrotalcite. Table 3 shows the average width of the primary particles in the resin, the average width of the secondary particles in the resin, and the monodispersity in the resin, respectively.

In the raw material preparation step of Example 1, zinc chloride (Wako Pure Chemical) was dissolved in deionized water in addition to magnesium chloride hexahydrate (Wako Pure Chemical) and aluminum chloride hexahydrate (Wako Pure Chemical). An aqueous solution of magnesium 0.15 mol / L, zinc 0.05 mol / L and aluminum 0.1 mol / L was obtained. To this aqueous solution, 1.75 equivalents of sodium lactate (Kishida Chemical) was added to aluminum to prepare a water-soluble composite metal salt aqueous solution. On the other hand, sodium hydroxide (Wako Pure Chemical Industries, Ltd.) was dissolved in deionized water so as to have a concentration of 0.8 mol / L to prepare an aqueous alkali metal hydroxide solution. In the subsequent steps, a sample was prepared in the same manner to obtain a suspension of hydrotalcite D. Subsequent steps were carried out in the same manner as in Example 1 to obtain the paste PVC D of the present invention. Table 1 shows the production conditions of hydrotalcite D, the chemical composition of hydrotalcite D, crystal strain in the <003> direction, and the specific surface area of the BET method in Table 2, the average particle size of paste PVC D, and the resin of hydrotalcite. Table 3 shows the average width of the primary particles in the resin, the average width of the secondary particles in the resin, and the monodispersity in the resin, respectively.

(Comparative Example 1)
In the raw material preparation step of Example 1, a sample was prepared in the same manner except that sodium lactate was not added, and a suspension of hydrotalcite E was obtained. Subsequent steps were carried out in the same manner as in Example 1 to obtain paste PVC E. Table 1 shows the production conditions of hydrotalcite E, the chemical composition of hydrotalcite E, the crystal strain in the <003> direction, and the specific surface area of the BET method in Table 2, the average particle size of paste PVC E, and the resin of hydrotalcite. Table 3 shows the average width of the primary particles in the resin, the average width of the secondary particles in the resin, and the monodispersity in the resin, respectively.

(Comparative Example 2)
In the aging step of Example 1, a sample was prepared in the same manner except that the mixture was aged at 120 ° C. for 24 hours using an autoclave to obtain a suspension of hydrotalcite F. Subsequent steps were carried out in the same manner as in Example 1 to obtain paste PVC F. Table 1 shows the production conditions of hydrotalcite F, the chemical composition of hydrotalcite F, crystal strain in the <003> direction, and the specific surface area of the BET method in Table 2, the average particle size of paste PVC F, and the resin of hydrotalcite. Table 3 shows the average width of the primary particles in the resin, the average width of the secondary particles in the resin, and the monodispersity in the resin, respectively.

(Comparative Example 3)
In the aging step of Example 1, a sample was prepared in the same manner except that the aging was eliminated, and a suspension of hydrotalcite G was obtained. Subsequent steps were carried out in the same manner as in Example 1 to obtain paste PVC G. Table 1 shows the production conditions of hydrotalcite G, the chemical composition of hydrotalcite G, crystal strain in the <003> direction, and the specific surface area of the BET method in Table 2, the average particle size of paste PVC G, and the resin of hydrotalcite. Table 3 shows the average width of the primary particles in the resin, the average width of the secondary particles in the resin, and the monodispersity in the resin, respectively.

(Comparative Example 4)
In the aging step of Example 1, the hydrotalcite suspension after the aging treatment was dehydrated, vacuum dried, and then pulverized to obtain a hydrotalcite H powder. Then, in the polymerization step, 0.5 part by weight of the hydrotalcite H powder obtained above was added to the vinyl chloride resin latex with stirring with respect to 100 parts by weight of the vinyl chloride resin in the latex. Subsequent steps were carried out in the same manner to obtain paste PVC H. Table 3 shows the average particle size of the paste PVC H, the average width of the primary particles in the hydrotalcite resin, the average width of the secondary particles in the resin, and the monodispersity in the resin.

(Comparative Example 5)
In Example 1, the synthesis of hydrotalcite was omitted, and a sample was prepared in the same manner except that hydrotalcite was not added during the polymerization step to obtain Paste PVC I. The average particle size of the paste PVC I is shown in Table 3.

From Tables 1 and 2, it can be seen that the hydrotalcites of Examples 1 to 4 have a smaller lattice strain in the <003> direction and a larger BET method specific surface area than those of Comparative Examples 1 to 3.

From Table 3, it can be seen that the hydrotalcite contained in the paste PVC of Examples 1 to 4 has a small average width of the primary particles in the resin and a high monodispersity. In the hydrotalcites of Comparative Examples 1, 3 and 4, the average width of the primary particles in the paste PVC is small, but the monodispersity is low. The hydrotalcite of Comparative Example 2 has a high degree of monodispersity in the paste PVC, but has a large average width of the primary particles.

<Preparation of PVC plastisol>
Using the paste PVC A prepared in Example 1, the vinyl chloride plastisol of the present invention was prepared with the following formulation. A Hobart mixer (Hobar Mixer N-50 type, manufactured by THE HOBART MFG. Co.) was used for the adjustment. The results of the thermal stability test and the transparency test are shown in Table 4.
(Mixing)
Paste PVC sample: 100 parts by weight DOP (dioctyl phthalate): 60 parts by weight Ba-Zn-based stabilizer (AC-118, manufactured by ADEKA): 1 part by weight

Using the paste PVC B prepared in Example 2, the PVC plastisol of the present invention was prepared with the same composition as in Example 5. The results of the thermal stability test and the transparency test are shown in Table 4.

Using the paste PVC C prepared in Example 3, the PVC plastisol of the present invention was prepared with the same composition as in Example 5. The results of the thermal stability test and the transparency test are shown in Table 4.

Using the paste PVC D prepared in Example 4, the PVC plastisol of the present invention was prepared with the same composition as in Example 5. The results of the thermal stability test and the transparency test are shown in Table 4.

(Comparative Example 6)
Using the paste PVC E prepared in Comparative Example 1, the PVC plastisol was prepared with the same composition as in Example 5. The results of the thermal stability test and the transparency test are shown in Table 4.

(Comparative Example 7)
Using the paste PVC F prepared in Comparative Example 2, the PVC plastisol was prepared with the same composition as in Example 5. The results of the thermal stability test and the transparency test are shown in Table 4.

(Comparative Example 8)
Using the paste PVC G prepared in Comparative Example 3, the PVC plastisol was prepared with the same composition as in Example 5. The results of the thermal stability test and the transparency test are shown in Table 4.

(Comparative Example 9)
Using the paste PVC H prepared in Comparative Example 4, the PVC plastisol was prepared with the same composition as in Example 5. The results of the thermal stability test and the transparency test are shown in Table 4.

(Comparative Example 10)
Using the paste PVC I prepared in Comparative Example 5, the PVC plastisol was prepared with the same composition as in Example 5. The results of the thermal stability test and the transparency test are shown in Table 4.

(Comparative Example 11)
Using the paste PVC I prepared in Comparative Example 5 and the powdered hydrotalcite H prepared in Comparative Example 4, a vinyl chloride plastisol was prepared with the following formulation. A Hobart mixer (Hobar Mixer N-50 type, manufactured by THE HOBART MFG. Co.) was used for the adjustment. The results of the thermal stability test and the transparency test are shown in Table 4.
(Mixing)
Paste PVC sample: 99.5 parts by weight DOP (dioctyl phthalate): 60 parts by weight Ba-Zn-based stabilizer (AC-118, manufactured by ADEKA): 1 part by weight Powdered hydrotalcite: 0.5 parts by weight

From Table 4, it can be seen that the PVC molded products of Examples 5 to 8 are superior in both thermal stability and transparency as compared with Comparative Examples 6 to 11.

The PVC molded product using the paste PVC of the present invention has higher thermal stability and transparency than the conventional ones. The vinyl chloride plastisol containing the paste PVC of the present invention is suitably used for molding of wallpaper, tile carpets, gloves, automobile undercoats and the like.

Claims (7)

A vinyl chloride resin composition for paste containing 0.05 parts by weight or more and less than 5 parts by weight of hydrotalcite represented by the following (formula 1) with respect to 100 parts by weight of the vinyl chloride resin for paste. A vinyl chloride resin composition for paste, wherein the hydrotalcite in the vinyl chloride resin composition for paste satisfies the following (A) and (B).
^{_{(M 2+) 1-X (}} M 3+) X (OH) 2 (A n-) X / n · mH 2 O ( Equation 1)
(Wherein in ^{M 2+} is a divalent metal of at least one or ^{more, M 3+} is at least one kind of trivalent ^{metal, A n-represents} n-valent anion, n is an integer of 1 to 6, respectively, x And m are in the range of 0.17 ≦ x ≦ 0.36 and 0 ≦ m ≦ 10, respectively).
(A) The average width of the primary particles in the resin by the SEM method is 5 nm or more and 200 nm or less;
(B) The monodispersity in the resin represented by the following formula is 50% or more;
Monodispersity in resin (%) = (average width of primary particles in resin by SEM method / average width of secondary particles in resin by SEM method) × 100 The vinyl chloride resin composition for paste according to claim 1, wherein the hydrotalcite according to claim 1 has a lattice strain of 3 × 10 ^{-3 or less in the <003> direction by an X-ray diffraction method.} The vinyl chloride resin composition for paste according to claim 1, wherein M ²⁺ is at least one selected from the group consisting of Mg and Zn, and M ^{3+ is Al in the hydrotalcite according to claim 1.} .. The vinyl chloride resin composition for paste according to claim 1, wherein the hydrotalcite according to claim 1 has a BET method specific surface area of 20 to 600 m ^{2 / g.} A vinyl chloride-based plastisol containing the vinyl chloride-based resin composition for paste according to claim 1 and a plasticizer. A vinyl chloride-based resin molded product comprising the vinyl chloride-based plastisol according to claim 5. A method for producing a vinyl chloride resin composition for paste, which comprises the following six steps.
(Step 1) A raw material preparation step for preparing a water-soluble composite metal salt aqueous solution and an alkali metal hydroxide aqueous solution. However, the aqueous solution of the water-soluble composite metal salt contains a divalent metal salt, a trivalent metal salt, and a monovalent organic acid and / or an organic acid salt that forms a complex with the trivalent metal.
(Step 2) The water-soluble composite metal salt aqueous solution and the alkali metal hydroxide aqueous solution prepared in (Step 1) are continuously reacted at a reaction temperature of 0 to 60 ° C. and a reaction pH of 8.5 to 11.5 to obtain hydrotalcite. Reaction step to obtain a suspension containing.
(Step 3) A washing step in which the suspension containing hydrotalcite obtained in (Step 2) is dehydrated, washed with water, and suspended in an aqueous solvent.
(Step 4) A aging step in which the suspension containing the washed hydrotalcite obtained in (Step 3) is stirred and held at 0 to 100 ° C. for 1 to 60 hours.
(Step 5) A polymerization step of obtaining a vinyl chloride resin latex by polymerizing a vinyl chloride monomer alone or a mixture of a vinyl chloride monomer and another monomer copolymerizable with vinyl chloride. However, the suspension containing hydrotalcite prepared in (Step 4) is polymerized with respect to 100 parts by weight of the vinyl chloride resin in an amount of 0.05 parts by weight or more and less than 5 parts by weight in terms of the solid content of hydrotalcite. It is added at any time before, during polymerization, and after completion of polymerization.
(Step 6) A drying step of spray-drying the vinyl chloride resin latex obtained in (Step 5).

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