Plastisol composition

Abstract

This invention provides a plastisol composition and its applications that offer excellent storage stability, as well as superior processability and mechanical properties during low-temperature processing at around 80°C, making it ideal for use as a coating agent, particularly for automotive underbody coatings and automotive sealants. [Solution] A plastisol composition comprising 100 parts by weight of a vinyl chloride-vinyl acetate copolymer having an average content of vinyl acetate polymerization units of 5 to 20% by weight, and 80 to 170 parts by weight of a plasticizer that satisfies at least the following (1) and (2). (1)23℃, shear rate 4s -1 The viscosity measured in the viscoelasticity test under these measurement conditions was 15,000 to 50,000 mPa·s. (2) Hansen's solubility parameter is 19-22 (J / cm²) 3 ) 1 / 2 .

Description

[Technical Field]

[0001] The present invention relates to a plastisol composition comprising at least a specific vinyl chloride-vinyl acetate copolymer and a specific plasticizer, and more particularly to a plastisol composition applicable to low-temperature processing at around 80°C and useful as a coating agent, especially for automotive underbody coatings and automotive sealants suitable for low-temperature processing, and its applications. [Background technology]

[0002] From the perspective of reducing environmental impact, measures to reduce carbon dioxide emissions and conserve energy are being implemented in the automotive underbody coating and sealant painting processes. As part of this, there is a demand to reduce carbon dioxide emissions generated by the energy consumption of baking ovens in the painting process, and to achieve energy conservation and carbon dioxide emission reduction, the temperature of the baking ovens is being lowered. However, simply using low-temperature processing is not practical as it makes it difficult to express the functions and performance of the molded body, such as its inherent mechanical properties. Therefore, there is a need for materials, paints, and coatings that are suitable for low-temperature processing.

[0003] Vinyl chloride resins for paste processing (hereinafter sometimes referred to as paste PVC) are generally prepared by kneading them with plasticizers, fillers, stabilizers, or other compounding agents to create a plastisol composition, which can then be molded and formed into films by solidification (gelling) through heating (usually around 180-200°C). They are widely used for automotive underbody coatings and automotive sealants. As a paste PVC that can gel and melt at a relatively low temperature of around 140°C and has excellent mechanical strength, vinyl chloride / vinyl acetate copolymer resins have been proposed (see, for example, Patent Document 1). Furthermore, as a plastisol composition that can obtain mechanical strength at a processing temperature of 100-120°C, a composition has been proposed that blends vinyl chloride-vinyl acetate copolymer resin with (meth)acrylic resin and incorporates blocked isocyanate as an adhesive (see, for example, Patent Document 2). [Prior art documents]

Patent Document

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in recent years, the demand for reducing the energy consumption in the manufacturing processes in the industrial world, especially in the automotive industry, has been even higher, and raw materials, coating agents, coating materials, etc. that can be processed at lower temperatures, particularly 8℃ or lower, are required. In the proposals of Patent Documents 1 and 2, the processability, mechanical properties, etc. at baking temperatures below 100℃ have not been considered at all, and it has been difficult to meet this requirement. Also, in these applications, long-term storage (preservation) stability after the preparation of plastisol is required, and a plastisol with little change in sol viscosity over time is desired.

[0006] Note that the low-temperature materials and technologies during molding processing contribute to the reduction of carbon dioxide emissions and energy conservation, contribute to the promotion of an inclusive and sustainable industry, and are expected as one of the basic technologies necessary for a sustainable society such as SDGs.

[0007] Therefore, the present invention provides a plastisol composition having excellent storage stability, processability during low-temperature (more specifically, 80℃) processing, and mechanical properties, and excellent characteristics as a coating agent, particularly for automotive underbody coating and automotive sealant, and its use.

Means for Solving the Problems

[0008] As a result of intensive studies on the above problems, the present inventor has found that a plastisol composition containing at least a vinyl chloride-vinyl acetate copolymer having a specific vinyl acetate polymerization unit content and a plasticizer having specific viscosity and solubility parameter values is excellent in storage stability, processability during low-temperature (specifically, 80 °C) processing, and mechanical strength, and has thus completed the present invention.

[0009] That is, the present invention relates to a plastisol composition characterized by containing 80 to 170 parts by weight of a plasticizer satisfying at least the following (1) and (2) with respect to 100 parts by weight of a vinyl chloride-vinyl acetate copolymer having an average vinyl acetate polymerization unit content of 5 to 20% by weight. (1) The viscosity in viscoelasticity measurement under the measurement conditions of 23 °C and a shear rate of 4 s -1 is 15,000 to 50,000 mPa·s. (2) The Hansen solubility parameter is 19 to 22 (J / cm 3 ) 1 / 2 .

[0010] Hereinafter, the present invention will be described in detail.

[0011] The plastisol composition of the present invention is a plastisol composition containing at least a vinyl chloride-vinyl acetate copolymer and a plasticizer.

[0012] The vinyl chloride-vinyl acetate copolymer constituting the plastisol composition of the present invention is a vinyl chloride-vinyl acetate copolymer having an average content of vinyl acetate polymerization units of 5 to 20% by weight. It is particularly suitable for automotive underbody coatings and automotive sealants, which are suitable for low-temperature processing, and is excellent in terms of strength characteristics. Therefore, the average content of vinyl acetate polymerization units is preferably 9 to 18% by weight, and more preferably 11 to 16% by weight. If the average content of vinyl acetate polymerization units is less than 5% by weight, low-temperature processing of the plastisol composition becomes difficult, or the molded product subjected to low-temperature processing has low mechanical strength. On the other hand, if the average content of vinyl acetate polymerization units exceeds 20% by weight, the viscosity of the sol changes significantly over time, resulting in poor long-term storage stability. The average content of vinyl acetate polymerization units can be measured, for example, with an infrared spectrophotometer at 1430 cm⁻¹. -1 Absorption values ​​at the absorption peak top due to in-plane angle bending in the vicinity of CH and 1740 cm -1 It can be calculated from the absorption value of the absorption peak top due to the expansion and contraction of the C=O region in the vicinity.

[0013] The vinyl chloride-vinyl acetate copolymer is preferably a vinyl chloride-vinyl acetate copolymer for paste processing, as it is suitable for plastisol compositions and paste processing. The vinyl chloride-vinyl acetate copolymer for paste processing may be any vinyl chloride-vinyl acetate copolymer that is generally known as suitable for paste processing. For example, any vinyl chloride-vinyl acetate copolymer for paste processing obtained by polymerizing vinyl chloride monomer and vinyl acetate monomer by emulsion polymerization, microsuspension polymerization, seed emulsion polymerization, seed microsuspension polymerization, etc., can be used. Commercial products may also be used.

[0014] In addition, the vinyl chloride-vinyl acetate copolymer is excellent in handleability when made into a plastisol composition, has excellent absorbability of plasticizers, and can provide a plastisol composition excellent in long-term storage stability and mechanical strength. Therefore, it is preferably vinyl chloride-vinyl acetate copolymer particles composed of primary particles having a volume-based median diameter of 0.5 to 30 μm. Such vinyl chloride-vinyl acetate copolymer particles can be produced, for example, by removing the water from a vinyl chloride-vinyl acetate copolymer latex obtained by an emulsion polymerization method, a micro-suspension polymerization method, a seed emulsion polymerization method, a seed micro-suspension polymerization method, or the like. At that time, as a method for removing water from the vinyl chloride-vinyl acetate copolymer latex, for example, methods such as spray drying, fluidized bed drying, ventilation drying, rotary drying, and drying by conduction heating can be mentioned. Among them, since water can be efficiently removed, a method of obtaining granules / particles by spray drying is preferable. Also, if the granules / particles are too large, they may be pulverized. The volume-based median diameter of the primary particles can be obtained, for example, from the central value of the volume-based particle size distribution measured by a disk centrifuge type particle size distribution measuring device for a vinyl chloride-vinyl acetate copolymer latex before water removal, a dispersion liquid in which vinyl chloride-vinyl acetate copolymer particles are dispersed into primary particles, or the like.

[0015] As the plasticizer constituting the plastisol composition of the present invention, (1) the viscosity in viscoelasticity measurement under the measurement conditions of 23°C and a shear rate of 4 s -1 is 15,000 to 50,000 mPa·s, preferably 15,000 to 45,000 mPa·s, and (2) the Hansen solubility parameter is 19 to 22 (J / cm 3 ) 1 / 2 , preferably 19 to 21 (J / cm 3 ) 1 / 2 Any plasticizer that satisfies these conditions may be used. Among them, in particular, since it results in a plastisol composition excellent in long-term storage stability and heat formability during solidification (gelation), (3) at 80°C and a shear rate of 4 s -1It is preferable that the plasticizer satisfies a viscosity of 1 to 300 mPa·s in viscoelasticity measurements under the specified measurement conditions. Examples of such plasticizers include bisphenol A type (Hansen solubility parameter (calculated value) 20.4 (J / cm³). 3 ) 1 / 2 ), Bisphenol F type (Hansen's solubility parameter (calculated value) 22.0 (J / cm³) 3 ) 1 / 2 Examples of epoxy resins include those represented by ), and liquid epoxy resins, and more preferably bisphenol A type epoxy resins. Here, if the viscosity at 23°C is less than 15,000 mPa·s, it will have poor long-term storage stability and poor gelation and moldability after storage. On the other hand, if it exceeds 50,000 mPa·s, the viscosity when forming a sol will be high, resulting in poor workability and difficulty in preparing the plastisol composition. Also, the solubility parameter is 19 (J / cm³). 3 ) 1 / 2 If the solubility parameter is less than 22 (J / cm³), the molded product obtained by processing the plastisol composition at low temperatures will have inferior strength. On the other hand, if the solubility parameter is 22 (J / cm³), 3 ) 1 / 2 If the viscosity exceeds a certain level, the viscosity of the sol will change significantly over time, resulting in poor storage stability. The viscosity of the plasticizer can be measured using, for example, a viscoelasticity measuring device, such as the MCR302 (product name) manufactured by Anton-Paar. Furthermore, Hansen's solubility parameter can be calculated using, for example, computer software (product name) HSPiP (Hansen Solubility Parameter in Practice).

[0016] The plastisol composition of the present invention exhibits excellent storage stability, and even when processed under low-temperature conditions of 80°C, it has excellent processability and mechanical strength, making it particularly excellent as a coating agent, and even more so for automotive underbody coatings and automotive sealants. The amount of plasticizer blended with 100 parts by weight of vinyl chloride-vinyl acetate copolymer is 80 to 170 parts by weight, and it is preferable that the amount is 100 to 150 parts by weight, as this provides an excellent balance between long-term storage stability and low-temperature processability, making it suitable for low-temperature processing as a plastisol composition for automotive underbody coatings and automotive sealants. If the amount of plasticizer blended is less than 80 parts by weight, plasticization will be insufficient, making it difficult to prepare the plastisol composition. On the other hand, if the amount blended exceeds 170 parts by weight, the molded product when the plastisol composition is subjected to low-temperature processing will have inferior strength.

[0017] The plastisol composition of the present invention may contain additives commonly added to plastisol compositions made of vinyl chloride resin for paste processing, such as fillers, stabilizers, antioxidants, flame retardants, lubricants, ultraviolet absorbers, colorants such as pigments, surfactants, antistatic agents, diluents, etc., as long as they do not depart from the purpose of the present invention, and the amounts of these additives may also be within the range of commonly used additives.

[0018] The plastisol composition of the present invention can be prepared by uniformly mixing and dispersing a vinyl chloride-vinyl acetate copolymer, a plasticizer, and other additives as needed using conventionally known mixing and dispersing machines and kneaders, such as a kneader, disper, planetary mixer, attritor, ball mill, grain mill, blender, twin-screw mixer, vertical high-speed stirrer, roll mill, dissolver, etc.

[0019] Furthermore, the plastisol composition of the present invention exhibits excellent mechanical properties, especially in low-temperature processing, and is particularly excellent for automotive underbody coatings and sealants. Therefore, it is preferable that the tensile strength conforming to JIS K6251 be 0.5 MPa or higher. As a method for measuring the tensile strength in this case, for example, the plastisol composition is heated at 80°C for 30 minutes to form a 2 mm thick sheet, a JIS No. 3 dumbbell test piece is prepared from the sheet, and the strength is measured at 23°C and 50 mm / min in accordance with JIS K6251.

[0020] The plastisol composition of the present invention exhibits excellent storage stability, processability, and mechanical properties even under low processing conditions of 80°C, making it suitable for various applications such as films, sheets, wallpaper, flooring, and foamed sheets, particularly as a coating agent, and even as an underbody coating agent and sealant for automobiles. [Effects of the Invention]

[0021] The plastisol composition of the present invention exhibits excellent storage stability and mechanical properties when processed at low temperatures (specifically, 80°C), and has excellent properties as a coating agent, particularly for automotive underbody coatings and automotive sealants. [Examples]

[0022] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0023] The following describes the evaluation and measurement methods for vinyl chloride-vinyl acetate copolymers and plastisol compositions.

[0024] <Average content of vinyl acetate polymerization units> The average content (by weight) of vinyl acetate polymerization units contained in the vinyl chloride-vinyl acetate copolymer (sometimes referred to as VAc content) was calculated using the following formula with a measurement sample prepared by mixing 100 mg of vinyl chloride-vinyl acetate copolymer and 10 mg of potassium bromide, grinding and shaping it, and using an infrared spectrophotometer (Shimadzu Corporation, product name FTIR-8100A). VAc content=(3.73×B / A+0.024)×1.04 A: 1430cm -1 Abs. value of the absorption peak top due to in-plane angle bending in the vicinity of CH. B: 1740cm -1 Abs. value of the absorption peak top due to C=O expansion in the vicinity.

[0025] <Primary particle size of vinyl chloride-vinyl acetate copolymer> The obtained vinyl chloride-vinyl acetate copolymer latex was subjected to a disk centrifugal particle size distribution analyzer (Luft Japan Co., Ltd., product name DC24000UHR) to measure the volume-based primary particle size distribution, and the volume-based median diameter, which is the central value of the distribution, was defined as the particle size.

[0026] <Hansen solubility parameters for plasticizers> Hansen's solubility parameter (SP value) is a value expressed as δ by the following formula (unit: J / cm²). 3 ) 1 / 2 ) δ=(δd 2 +δp 2 +δh 2 ) 1 / 2 Here, δd represents the dispersion term, δp represents the polarity term, and δh represents the hydrogen bonding term (all units are (J / cm)). 3 ) 1 / 2 ). The δ, δd, δp, and δh values ​​for each plasticizer were calculated using commercially available computer software (product name) HSPiP (Hansen Solubility Parameter in Practice).

[0027] <Viscosity of plasticizers> At 23°C and 80°C, using a viscoelasticity measuring device (Anton-Paar, product name MCR302), parallel plate PP25 / P2 was measured at a shear rate of 4s. -1 It was measured using [this method].

[0028] <Thickening rate of plastisol composition> The obtained plastisol composition was stored at 23°C for 24 hours, and then measured using a viscoelasticity analyzer (Anton-Paar, product name MCR302) with a parallel plate PP25 / P2 at a shear rate of 4s. -1 The viscosity measured was defined as the initial viscosity. Furthermore, after storage at 40°C for 7 days, the viscosity (β) was measured using the same method as the initial viscosity, and the viscosity increase rate (%) was calculated from this value and the initial viscosity (α) using the following formula. As one guideline for evaluating long-term storage stability, a viscosity increase rate of 1000% or less was judged to have excellent long-term storage stability. Thickening rate (%)=((β-α) / α)×100 <Tensile strength> A plastisol composition that had been kneaded and defoamed was applied to release paper and heated at 80°C for 30 minutes to produce a 2 mm thick paste PVC sheet. Test specimens were prepared from the obtained paste PVC sheet using a JIS No. 3 dumbbell, and markings were made in the center of the specimen at 20 mm intervals. The specimen was then pulled at a speed of 50 mm / min at 23°C in accordance with JIS K6251, and the load at which it broke was measured to determine the breaking strength. As one criterion for evaluating strength, specimens with a tensile strength of 0.5 MPa or higher were judged to have superior strength.

[0029] Synthesis Example 1 (Synthesis example of a seed containing an initiator, etc.) 1m 3360 kg of deionized water, 300 kg of vinyl chloride monomer, 10.5 kg of lauroyl peroxide, and 30 kg of 15% by weight sodium dodecylbenzenesulfonate aqueous solution were charged into an autoclave. The polymerization solution was circulated using a homogenizer for 2 hours to homogenize it, and then the temperature was raised to 45°C to proceed with polymerization. After the pressure dropped by 0.2 MPa from the saturated vapor pressure of vinyl chloride monomer at 45°C, the unreacted vinyl chloride monomer was recovered. The resulting initiator-containing seed latex (hereinafter abbreviated as Seed 1) had a particle size of 0.60 μm and a solid content concentration of 32%.

[0030] Synthesis Example 2 (Synthesis example of seed containing initiator, etc.) 1m 3 360 kg of deionized water, 300 kg of vinyl chloride monomer, 5.3 kg of lauroyl peroxide, and 30 kg of 15 wt% sodium dodecylbenzenesulfonate aqueous solution were charged into a stainless steel autoclave. After homogenization treatment by circulating the mixture for 3 hours using a homogenizer, the temperature of the reaction system was raised to 45°C to start polymerization. After the pressure in the polymerization system decreased, the unreacted vinyl chloride monomer was recovered, and a vinyl chloride resin seed latex (hereinafter abbreviated as Seed 2) was obtained with a solid content of 35 wt%, a particle size of 0.55 μm, and containing 2 wt% lauroyl peroxide relative to the vinyl chloride resin.

[0031] Preparation Example 1 In a 2.5-liter autoclave, 500 g of deionized water, 449 g of vinyl chloride monomer and 159 g of vinyl acetate monomer were added as the first-stage monomers, 8.6 g of 5% sodium lauryl sulfate aqueous solution, 81 g of Seed 1, 4 g of 0.1% copper sulfate aqueous solution, and 10.6 g of a 2 wt% sodium phosphate / 1 wt% potassium hydroxide mixed aqueous solution were added as a buffer. The temperature of this reaction mixture was then raised to 35°C to start the first-stage polymerization, and a 0.06 wt% ascorbic acid aqueous solution was continuously added throughout the entire polymerization time to maintain the polymerization temperature. A total of 210 g of 0.06 wt% ascorbic acid aqueous solution was added throughout the entire polymerization time. When the polymerization conversion rate reached 50%, 128 g of vinyl chloride monomer was added to the 2.5-liter autoclave as the second-stage monomer, and the second-stage polymerization was continued at a polymerization temperature of 35°C. Furthermore, when the polymerization conversion rate reached 80% of the sum of the first and second stage monomers, 64 g of vinyl chloride monomer was added to a 2.5-liter autoclave as the third stage monomer, and the third stage polymerization was continued at a polymerization temperature of 35°C until the polymerization was terminated when the polymerization conversion rate reached 89% of the sum of the mixed monomers. During the entire polymerization process, 120 g of 5% sodium lauryl sulfate aqueous solution was continuously added. The total polymerization time from start to finish was 758 minutes.

[0032] Then, the unreacted monomers were recovered to form a latex, which was spray-dried in a spray dryer at a hot air inlet temperature of 158°C and an outlet temperature of 55°C to obtain vinyl chloride-vinyl acetate copolymer particles for paste processing.

[0033] The obtained vinyl chloride-vinyl acetate copolymer had an average vinyl acetate polymerization unit content of 13.9% by weight and a primary particle volume-based median diameter of 1.4 μm.

[0034] Preparation Example 2 In a 2.5-liter autoclave, 500 g of deionized water, 484 g of vinyl chloride monomer and 108 g of vinyl acetate monomer were added as the first-stage monomers, 8.6 g of 5% sodium lauryl sulfate aqueous solution, 84 g of Seed 1, 4 g of 0.1% copper sulfate aqueous solution, and 10.6 g of a 2 wt% sodium phosphate / 1 wt% potassium hydroxide mixture was added as a buffer. The temperature of this reaction mixture was then raised to 35°C to start the first-stage polymerization, and a 0.06 wt% ascorbic acid aqueous solution was continuously added throughout the entire polymerization time to maintain the polymerization temperature. A total of 218 g of 0.06 wt% ascorbic acid aqueous solution was added throughout the entire polymerization time. When the polymerization conversion rate reached 50%, 138 g of vinyl chloride monomer was added to the 2.5-liter autoclave as the second-stage monomer, and the second-stage polymerization was continued at a polymerization temperature of 35°C. Furthermore, when the polymerization conversion rate reached 80% of the sum of the first and second stage monomers, 69 g of vinyl chloride monomer was added to a 2.5-liter autoclave as the third stage monomer, and the third stage polymerization was continued at a polymerization temperature of 35°C until the polymerization was terminated when the polymerization conversion rate reached 89% of the sum of the mixed monomers. During the entire polymerization process, 120 g of 5% sodium lauryl sulfate aqueous solution was continuously added. The total polymerization time from start to finish was 792 minutes.

[0035] Then, the unreacted monomer was recovered to form a latex, 40 g of a 10 wt% polyoxyalkylene alkyl ether aqueous solution was added, and spray drying was performed using a spray dryer with a hot air inlet temperature of 158°C and an outlet temperature of 55°C to obtain vinyl chloride-vinyl acetate copolymer as vinyl chloride-vinyl acetate copolymer particles for paste processing.

[0036] The obtained vinyl chloride-vinyl acetate copolymer had an average vinyl acetate polymerization unit content of 9.0% by weight and a primary particle volume-based median diameter of 1.4 μm.

[0037] Preparation Example 3 In a 2.5-liter autoclave equipped with a stirrer, 210 g of deionized water, 25 g of lauroyl peroxide, 792 g of 2 wt% water-soluble polyvinyl alcohol, and 56 g of a 2 wt% sodium phosphate / 1 wt% potassium hydroxide mixture as a buffer were charged, and vacuum degassing was performed. After degassing, 576 g of vinyl chloride monomer and 143 g of vinyl acetate monomer were charged, and homogenization treatment was performed using a homogenizer for 40 minutes. After homogenization treatment, the temperature inside the can was heated to 35°C, and polymerization was started. Polymerization was stopped when the pressure inside the can reached 0.18 MPa. After polymerization was complete, the unreacted monomers in the can were recovered as latex, filtered, and then spray-dried in a spray dryer at a hot air inlet temperature of 158°C and an outlet temperature of 55°C to obtain vinyl chloride-vinyl acetate copolymer as vinyl chloride-vinyl acetate copolymer particles for paste processing.

[0038] The obtained vinyl chloride-vinyl acetate copolymer had an average vinyl acetate polymerization unit content of 10.9% by weight and a primary particle volume-based median diameter of 14.1 μm.

[0039] Example 1 To 100 parts by weight of the vinyl chloride-vinyl acetate copolymer obtained in Preparation Example 1, a bisphenol A type epoxy resin ((product name) Adeka Resin EP-4100E, manufactured by ADEKA Corporation; viscosity 19600 mPa·s, Hansen solubility parameter 20.4 (J / cm)) was used as a plasticizer. 3 ) 1 / 2 120 parts by weight were added, kneaded and defoamed using a dissolver at 23°C for 3 minutes to obtain a plastisol composition.

[0040] The various physical properties and sheet properties of the obtained plastisol composition were evaluated. The results are shown in Table 1.

[0041] Example 2 To 100 parts by weight of the vinyl chloride-vinyl acetate copolymer obtained in Preparation Example 1, a bisphenol A type epoxy resin ((product name) Adeka Resin EP-4100TX, manufactured by ADEKA Corporation; viscosity 25900 mPa·s, Hansen solubility parameter 20.4 (J / cm)) was used as a plasticizer. 3) 1 / 2 120 parts by weight were added, kneaded and defoamed using a dissolver at 23°C for 3 minutes to obtain a plastisol composition.

[0042] The various physical properties and sheet properties of the obtained plastisol composition were evaluated. The results are shown in Table 1.

[0043] Example 3 A plastisol composition was obtained using the same method as in Example 1, except that the vinyl chloride-vinyl acetate copolymer obtained in Preparation Example 2 was used. A paste vinyl sheet was then prepared, and its physical properties were evaluated. The results are shown in Table 1.

[0044] Example 4 To 100 parts by weight of the vinyl chloride-vinyl acetate copolymer obtained in Preparation Example 2, a bisphenol A type epoxy resin ((product name) Adeka Resin EP-4100E, manufactured by ADEKA Corporation; viscosity 19600 mPa·s, Hansen solubility parameter 20.4 (J / cm)) was used as a plasticizer. 3 ) 1 / 2 120 parts by weight of ), 70 parts by weight of fatty acid-treated calcium carbonate (product name SP-60, manufactured by Takehara Chemical Industry Co., Ltd.) as a thixotropic agent, 70 parts by weight of heavy calcium carbonate (product name NN500, manufactured by Sankyo Seifun Co., Ltd.) as a filler, and 20 parts by weight of naphthenic hydrocarbon solvent (product name Exxsol D80, manufactured by Tonen General Sekiyu Co., Ltd.) as a diluent were mixed and kneaded and defoamed at 23°C for 3 minutes using a dissolver to obtain a plastisol composition.

[0045] The various physical properties and sheet properties of the obtained plastisol composition were evaluated. The results are shown in Table 1.

[0046] Example 5 To 100 parts by weight of the vinyl chloride-vinyl acetate copolymer obtained in Preparation Example 1, a bisphenol A type epoxy resin ((product name) Adeka Resin EP-4100E, manufactured by ADEKA Corporation; viscosity 19600 mPa·s, Hansen solubility parameter 20.4 (J / cm)) was used as a plasticizer. 3 ) 1 / 2) 150 parts by weight was added, kneaded and defoamed using a dissolver at 23°C for 3 minutes to obtain a plastisol composition.

[0047] The various physical properties and sheet properties of the obtained plastisol composition were evaluated. The results are shown in Table 1.

[0048] Example 6 A plastisol composition was obtained using the same method as in Example 1, except that the vinyl chloride-vinyl acetate copolymer obtained in Preparation Example 3 was used. A paste vinyl sheet was then prepared, and its physical properties were evaluated. The results are shown in Table 1.

[0049] [Table 1]

[0050] Preparation Example 4 720 g of deionized water, 800 g of vinyl chloride monomer, 8.8 g of 5% sodium lauryl sulfate aqueous solution, 98 g of Seed 2, 8 g of 0.1% copper sulfate aqueous solution, and 18.5 g of a 0.9 wt% boric acid / 0.1 wt% potassium hydroxide mixed aqueous solution as a buffer were charged into a 2.5 liter autoclave. The temperature of this reaction mixture was then raised to 48°C to start polymerization, and a 0.05 wt% ascorbic acid aqueous solution was continuously added throughout the entire polymerization time to maintain the polymerization temperature. A total of 139 g of 0.05 wt% ascorbic acid aqueous solution was added throughout the entire polymerization time. Polymerization was terminated when the polymerization conversion rate reached 86% of the monomer. In addition, 60 g of 5% sodium lauryl sulfate aqueous solution was continuously added from the start to the end of polymerization. The total polymerization time from the start to the end of polymerization was 583 minutes.

[0051] Then, the unreacted monomers were recovered to form latex, which was spray-dried in a spray dryer at a hot air inlet temperature of 158°C and an outlet temperature of 55°C to obtain vinyl chloride polymer as vinyl chloride polymer particles for paste processing.

[0052] The obtained vinyl chloride polymer had a primary particle volume-based median diameter of 1.3 μm.

[0053] Preparation Example 5 In a 2.5-liter autoclave, 500 g of deionized water, 379 g of vinyl chloride monomer and 259 g of vinyl acetate monomer were added as the first-stage monomers, 8.6 g of 5% sodium lauryl sulfate aqueous solution, 83 g of Seed 1, 4 g of 0.1% copper sulfate aqueous solution, and 10.6 g of a 2 wt% sodium phosphate / 1 wt% potassium hydroxide mixture was added as a buffer. The temperature of this reaction mixture was then raised to 35°C to start the first-stage polymerization, and a 0.06 wt% ascorbic acid aqueous solution was continuously added throughout the entire polymerization time to maintain the polymerization temperature. A total of 268 g of 0.06 wt% ascorbic acid aqueous solution was added throughout the entire polymerization time. When the polymerization conversion rate reached 50%, 108 g of vinyl chloride monomer was added to the 2.5-liter autoclave as the second-stage monomer, and the second-stage polymerization was continued at a polymerization temperature of 35°C. Furthermore, when the polymerization conversion rate reached 80% of the sum of the first and second stage monomers, 54 g of vinyl chloride monomer was added to a 2.5-liter autoclave as the third stage monomer, and the third stage polymerization was continued at a polymerization temperature of 35°C. Polymerization was terminated when the polymerization conversion rate reached 89% of the sum of the mixed monomers. During the entire polymerization process, 120 g of 5% sodium lauryl sulfate aqueous solution was continuously added. The total polymerization time from start to finish was 1276 minutes.

[0054] Then, the unreacted monomers were recovered to form a latex, which was spray-dried in a spray dryer at a hot air inlet temperature of 158°C and an outlet temperature of 55°C to obtain vinyl chloride-vinyl acetate copolymer particles for paste processing.

[0055] The obtained vinyl chloride-vinyl acetate copolymer had an average vinyl acetate polymerization unit content of 22.7% by weight, and the volume-based median diameter of the primary particles was 1.4 μm.

[0056] Comparative Example 1 A plastisol composition was obtained using the same method as in Example 1, except that the vinyl chloride polymer obtained in Preparation Example 4 was used. An attempt was made to prepare a sheet by heating at 80°C for 30 minutes, but the sheet could not be prepared as it did not harden (gel). The evaluation results are shown in Table 2.

[0057] Comparative Example 2 A plastisol composition was obtained in the same manner as in Example 1, except that the vinyl chloride-vinyl acetate copolymer obtained in Preparation Example 5 was used. The obtained plastisol composition solidified (gelled) during the initial viscosity measurement, so other evaluations could not be performed.

[0058] Comparative Example 3 To 100 parts by weight of the vinyl chloride-vinyl acetate copolymer obtained in Preparation Example 1, a bisphenol A type epoxy resin ((product name) Adeka Resin EP-4100E, manufactured by ADEKA Corporation; viscosity 19600 mPa·s, Hansen solubility parameter 20.4 (J / cm)) was used as a plasticizer. 3 ) 1 / 2 We attempted to prepare a plastisol composition by incorporating 60 parts by weight and kneading it at 23°C using a dissolver, but efficient kneading was difficult due to the absorption of the plasticizer, and we were unable to prepare a plastisol composition.

[0059] Comparative Example 4 To 100 parts by weight of the vinyl chloride-vinyl acetate copolymer obtained in Preparation Example 1, a bisphenol A type epoxy resin ((product name) Adeka Resin EP-4100E, manufactured by ADEKA Corporation; viscosity 19600 mPa·s, Hansen solubility parameter 20.4 (J / cm)) was used as a plasticizer. 3 ) 1 / 2 200 parts by weight were mixed, kneaded at 23°C for 3 minutes using a dissolver, and degassed to obtain a plastisol composition. A paste PVC sheet was prepared, and its physical properties were evaluated. The results are shown in Table 2. The obtained sheet had a low tensile strength of 0.10 MPa.

[0060] Comparative Example 5 To 100 parts by weight of the vinyl chloride-vinyl acetate copolymer obtained in Preparation Example 1, a bisphenol A type epoxy resin ((product name) Adeka Resin EP-4300E, manufactured by ADEKA Corporation; viscosity 13100 mPa·s, Hansen solubility parameter 20.4 (J / cm)) was used as a plasticizer. 3 ) 1 / 2 120 parts by weight of the compound were mixed, kneaded at 23°C for 3 minutes using a dissolver, and degassed to obtain a plastisol composition. A paste PVC sheet was prepared, and its physical properties were evaluated. The results are shown in Table 2. The obtained plastisol composition solidified (gelled) after being stored at 40°C for 7 days, indicating poor long-term storage stability.

[0061] Comparative Example 6 To 100 parts by weight of the vinyl chloride-vinyl acetate copolymer for paste processing obtained in Preparation Example 1, polycarbonate diol ((trade name) Nipponran 964, manufactured by Tosoh Corporation; viscosity 85200 mPa·s, Hansen solubility parameter 21.0 (J / cm)) was added as a plasticizer. 3 ) 1 / 2 We attempted to prepare a plastisol composition by incorporating 120 parts by weight and kneading it at 23°C using a dissolver, but efficient kneading was difficult due to the absorption of the plasticizer, and we were unable to prepare a plastisol composition.

[0062] Comparative Example 7 To 100 parts by weight of the vinyl chloride-vinyl acetate copolymer obtained in Preparation Example 2, an adipic acid-based polyester (product name: Adeka Sizer PN-5090, manufactured by ADEKA Corporation; viscosity 12400 mPa·s, Hansen solubility parameter 20.7 (J / cm²)) was added as a plasticizer. 3 ) 1 / 2 120 parts by weight of the compound were mixed, kneaded at 23°C for 3 minutes using a dissolver, and degassed to obtain a plastisol composition. A paste PVC sheet was prepared, and its physical properties were evaluated. The results are shown in Table 2. The obtained sheet had a low tensile strength of 0.09 MPa.

[0063] Comparative Example 8 To 100 parts by weight of the vinyl chloride-vinyl acetate copolymer obtained in Preparation Example 1, diisononyl phthalate ((trade name) DINP, manufactured by J-Plus Co., Ltd.) was used as a plasticizer; viscosity 70 mPa·s, Hansen solubility parameter 17.6 (J / cm²). 3 ) 1 / 2 100 parts by weight of ), 70 parts by weight of fatty acid-treated calcium carbonate (product name SP-60, manufactured by Takehara Chemical Industry Co., Ltd.) as a thixotropic agent, 70 parts by weight of heavy calcium carbonate (product name NN500, manufactured by Sankyo Seifun Co., Ltd.) as a filler, and 20 parts by weight of naphthenic hydrocarbon solvent (product name Exxsol D80, manufactured by Tonen General Sekiyu K.K.) as a diluent were mixed and kneaded and defoamed using a dissolver at 23°C for 3 minutes to obtain a plastisol composition, and a paste PVC sheet was prepared and its physical properties were evaluated. The results are shown in Table 2. The obtained plastisol composition had a high thickening rate of 4851%, which resulted in poor long-term storage stability.

[0064] [Table 2] [Industrial applicability]

[0065] The plastisol of the present invention exhibits excellent storage stability, as well as superior processability and mechanical properties even when processed at low temperatures such as 80°C. It possesses excellent properties as a coating agent, particularly for automotive underbody coatings and automotive sealants, and therefore has high industrial value.

Claims

1. A plastisol composition characterized by containing 80 to 170 parts by weight of a plasticizer that satisfies at least the following (1) and (2) per 100 parts by weight of a vinyl chloride-vinyl acetate copolymer having an average content of vinyl acetate polymerization units of 5 to 20% by weight. (1) 23℃, shear rate 4s －１ The viscosity measured in the viscoelasticity test under these measurement conditions is 15,000 to 50,000 mPa·s. (2) Hansen solubility parameter is 19-22 (J / cm²) ３ ) １ / ２ .

2. The plastisol composition according to claim 1, characterized in that the plasticizer further satisfies (3) below. (3) 80℃, shear rate 4s －１ The viscosity measured in viscoelasticity tests under these measurement conditions is 1 to 300 mPa·s.

3. The plastisol composition according to claim 1, characterized in that the plasticizer is an epoxy resin.

4. The plastisol composition according to claim 1, characterized in that the plasticizer is a bisphenol A type epoxy resin.

5. The plastisol composition according to claim 1, characterized in that the vinyl chloride-vinyl acetate copolymer is vinyl chloride-vinyl acetate copolymer particles containing primary particles with a volume-based median diameter of 0.5 to 30 μm.

6. The plastisol composition according to claim 1, characterized in that when formed into a 2 mm thick sheet under heating conditions of 80°C for 30 minutes, the tensile strength in accordance with JIS K6251 using a JIS No. 3 dumbbell test specimen is 0.5 MPa or more.

7. An automotive underbody coating agent characterized by comprising the plastisol composition described in claim 1.

8. A sealant characterized by comprising the plastisol composition described in claim 1.

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