Paste vinyl chloride resin for synthetic leather

Abstract

Provided is a vinyl chloride paste for synthetic leather, which enables the production of synthetic leather having excellent flexibility and tactile sensation. The synthetic leather preferably contains a paste vinyl chloride-based resin for synthetic leather as a constituent material for the skin layer and / or the foam layer, and the paste vinyl chloride-based resin for synthetic leather is a paste vinyl chloride-vinyl acetate copolymer containing 3-15 wt% of vinyl acetate residue units and having an average degree of polymerization of 900-2,200.

Description

Technical Field

[0001] This invention relates to vinyl chloride resins having properties suitable for use as materials for synthetic leather, and more particularly to vinyl chloride resins and synthetic leathers containing such vinyl chloride resins, wherein the vinyl chloride resins, by having a specific amount of vinyl acetate residue units and an average degree of polymerization, are capable of providing synthetic leather with excellent softness and feel. Background Technology

[0002] For vinyl chloride paste resins (hereinafter, sometimes simply referred to as vinyl chloride paste), they are generally prepared by mixing with plasticizers, fillers, stabilizers or other compounding agents to prepare vinyl chloride paste sols (hereinafter, sometimes simply referred to as vinyl chloride paste sols). Using this vinyl chloride paste sol, various molding and processing methods are used to apply it to various molded products such as wallpaper, carpet tiles, gloves.

[0003] Furthermore, as a synthetic leather made of vinyl chloride resin, it has been proposed to apply materials with high mechanical strength, excellent wear resistance, chemical resistance, and oil resistance to a wide range of fields, including furniture (such as automotive interiors), bags / pockets, footwear, clothing, and stationery (see, for example, Patent Document 1). While the softness of such synthetic leather can be improved by adding plasticizers, depending on the amount added, while improving softness, issues such as stickiness caused by the plasticizer, affecting the tactile feel, have also been observed.

[0004] Therefore, a method using a specific plasticizer has been proposed (see, for example, Patent Document 2).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 6-116875

[0008] Patent Document 2: Japanese Patent Application Publication No. 6-2281 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, in the solutions proposed in Patent Documents 1 and 2, synthetic leather and its composition were proposed, but no research was conducted on vinyl chloride paste as a material for synthetic leather. The effect was limited only by the research on plasticizers.

[0011] Therefore, the present invention provides a synthetic leather that can provide excellent softness and feel, and is suitable as a material for synthetic leather, as well as synthetic leather made from the ethylene chloride paste.

[0012] Problem Solving Methods

[0013] The inventors conducted in-depth research on the above-mentioned problems and found that a vinyl chloride-vinyl acetate copolymer containing a specific amount of vinyl acetate residue units and having a specific average degree of polymerization becomes a vinyl chloride paste suitable as a synthetic leather material with excellent softness and tactile feel, thus completing the present invention.

[0014] That is, the present invention includes the following [1] to [8].

[0015] [1] A synthetic leather paste vinyl chloride resin, which is a paste vinyl chloride-vinyl acetate copolymer containing 3 to 15% by weight of vinyl acetate residue units and having an average degree of polymerization of 900 to 2,200.

[0016] [2] According to the synthetic leather paste vinyl chloride resin described in [1], wherein,

[0017] The distribution of vinyl acetate residue unit content shows a continuous distribution with one maximum and a mode of 1 to 30% by weight. The particle size of the largest peak showing the cumulative weight frequency in the primary particle size ranges from 0.1 to 5 μm.

[0018] [3] A synthetic leather comprising a vinyl chloride-vinyl acetate copolymer containing 3 to 15% by weight of vinyl acetate residue units and having an average degree of polymerization of 900 to 2,200.

[0019] [4] The synthetic leather according to [3] is formed of at least an epidermis, a foam layer, and a base fabric.

[0020] The skin layer and / or foam layer contain a vinyl chloride-vinyl acetate copolymer containing 3 to 15% by weight of vinyl acetate residue units and having an average degree of polymerization of 900 to 2,200.

[0021] [5] The synthetic leather according to [4], wherein,

[0022] The skin layer contains 40 to 100 parts by weight of a vinyl chloride-vinyl acetate copolymer paste containing 3 to 15% by weight of vinyl acetate residue units and having an average degree of polymerization of 900 to 2,200.

[0023] [6] The synthetic leather according to [4] or [5], wherein,

[0024] The foam layer contains 50-150 parts by weight of plasticizer relative to 100 parts by weight of a vinyl chloride-vinyl acetate copolymer paste containing 3-15% by weight of vinyl acetate residue units and having an average degree of polymerization of 900-2,200.

[0025] [7] The synthetic leather according to [5] or [6], wherein,

[0026] The plasticizer is selected from at least one plasticizer selected from diisononyl phthalate, bis(2-ethylhexyl) terephthalate, diisodecyl phthalate, dibutyl phthalate, (2-ethylhexyl) adipate, diisononyl adipate, tri(2-ethylhexyl) trimellitate and triisodecyl trimellitate.

[0027] [8] A method for manufacturing synthetic leather, the method comprising: layering an epidermis, a foam layer and a base fabric,

[0028] The skin layer and the foam layer have undergone paste processing. The vinyl chloride sol used for the skin layer and / or the vinyl chloride sol used for the foam layer contain vinyl chloride-vinyl acetate copolymer and plasticizer. The vinyl chloride-vinyl acetate copolymer contains 3 to 15% by weight of vinyl acetate residue units and has an average degree of polymerization of 900 to 2,200.

[0029] The effects of the invention

[0030] Synthetic leather containing the PVC paste of the present invention has excellent softness and feel, and is expected to be used in a wide range of fields such as furniture (represented by automotive interiors), bags / pockets, footwear, clothing, and stationery. Detailed Implementation

[0031] The present invention will now be described in detail.

[0032] The vinyl chloride paste for synthetic leather of the present invention is a vinyl chloride-vinyl acetate copolymer containing 3-15% by weight of vinyl acetate residue units and having an average degree of polymerization of 900-2,200. In this vinyl chloride-vinyl acetate copolymer, the content of vinyl acetate residue units is 3-15% by weight (i.e., the content of vinyl acetate residue units is equivalent to 3-15 parts by weight relative to 100 parts by weight of the vinyl chloride-vinyl acetate copolymer). Particularly from the perspective of exhibiting excellent softness as synthetic leather, the content of vinyl acetate residue units is preferably 7-12% by weight (i.e., the content of vinyl acetate residue units is equivalent to 7-12 parts by weight relative to 100 parts by weight of the vinyl chloride-vinyl acetate copolymer). When the content of vinyl acetate residue units is less than 3% by weight, the softness of the synthetic leather becomes worse. On the other hand, when the content of vinyl acetate residue units exceeds 15% by weight, the viscosity of the vinyl chloride sol paste used in processing synthetic leather changes significantly over time, resulting in poor processability.

[0033] Furthermore, the average degree of polymerization of this vinyl chloride-vinyl acetate copolymer is 900 to 2,200, and particularly, for the purpose of providing an excellent material for synthetic leather, an average degree of polymerization of 1,000 to 2,000 is preferred. When the average degree of polymerization is less than 900, the mechanical strength of the synthetic leather deteriorates. On the other hand, when it exceeds 2,200, the processability of the synthetic leather deteriorates. It should be noted that the average degree of polymerization can be determined, for example, using a method based on JIS-K6721.

[0034] Considering the excellent viscosity of the vinyl chloride sol during preparation, which exhibits minimal viscosity change over time and can be used to produce synthetic leather with superior mechanical strength, the vinyl chloride sol for synthetic leather in this invention is preferably a vinyl chloride-vinyl acetate copolymer in which the distribution of vinyl acetate residue units exhibits a continuous distribution with a single maximum and a mode of 1 to 30% by weight. For example, methods for determining the distribution of vinyl acetate residue unit content can be employed such as: separating the vinyl acetate residue units by gradient dissolution using 2D-HPLC or liquid chromatography, determining the concentration of the separated components using an evaporative light scattering detector, and determining the distribution of vinyl acetate residue unit content. It should be noted that a continuous distribution with a single maximum within the range of 1 to 30% by weight of the vinyl acetate residue unit content indicates the compositional distribution of vinyl acetate residue units in the vinyl acetate-vinyl chloride copolymer, thereby showing the uniformity of the compositional distribution. A narrower distribution range, a smaller number of maximum values, and a stronger intensity of the maximum value indicate better uniformity.

[0035] Since the synthetic leather paste vinyl chloride of the present invention is a paste vinyl chloride, it is formed by the aggregation of primary particles of vinyl chloride-vinyl acetate copolymer. In terms of its primary particle size, in order to be suitable as a synthetic leather material with little viscosity change over time and excellent processability when making paste vinyl chloride sol, the primary particle size representing the maximum peak of cumulative weight frequency is preferably 0.1 to 5 μm, particularly preferably 0.5 to 3.0 μm, and even more preferably 1.0 to 2.0 μm.

[0036] The vinyl chloride-vinyl acetate copolymer used as the synthetic leather paste of the present invention can be any substance commonly known as a vinyl chloride-vinyl acetate copolymer suitable for paste processing. For example, it can be any substance among the vinyl chloride-vinyl acetate copolymers obtained by polymerizing vinyl chloride monomers and vinyl acetate monomers through emulsion polymerization, micro-suspension polymerization, seed emulsion polymerization, seed micro-suspension polymerization, etc. Alternatively, it can be a commercially available product.

[0037] The polyvinyl chloride paste for synthetic leather of the present invention can provide synthetic leather with excellent softness and feel. Examples of such synthetic leather include synthetic leather formed from at least an epidermis, a foam layer, and a base fabric. Among these, synthetic leather with a layered structure, having a base fabric as the substrate, a foam layer in the middle, and an epidermis on the outer surface, is preferred for achieving excellent feel and appearance design. Furthermore, the polyvinyl chloride paste for synthetic leather of the present invention can be used as a constituent material for the epidermis and / or the foam layer.

[0038] When the synthetic leather paste of the present invention is used as the epidermal layer material, especially due to its excellent softness and the absence of quality and hygiene problems such as seepage, it preferably contains 40 to 100 parts by weight of plasticizer relative to 100 parts by weight of the paste vinyl chloride-vinyl acetate copolymer, particularly preferably 50 to 90 parts by weight, and even more preferably 50 to 80 parts by weight. As the plasticizer at this time, it can be a plasticizer known as a plasticizer commonly used for vinyl chloride resins. Among them, in order to produce synthetic leather with an excellent balance of softness, permanent elongation and mechanical strength, it is preferred to select at least one plasticizer selected from diisononyl phthalate, bis(2-ethylhexyl) terephthalate, diisodecyl phthalate, dibutyl phthalate, (2-ethylhexyl) adipate, diisononyl adipate, tri(2-ethylhexyl) trimellitate and triisodecyl trimellitate. In order to produce synthetic leather with very excellent softness, it is preferred to select diisononyl phthalate (hereinafter, sometimes referred to as DINP).

[0039] In addition, when forming the skin layer, other pigments, diluents, inorganic fillers, heat stabilizers, viscosity modifiers, colorants, flame retardants, etc., can be used. As inorganic fillers, examples include calcium carbonate such as precipitated calcium carbonate, heavy calcium carbonate, and very fine calcium carbonate; magnesium carbonate; or silicates such as silicate, talc, diatomaceous earth, clay, and mica; aluminum hydroxide; and alumina. As heat stabilizers, examples include metal soaps such as magnesium stearate, aluminum stearate, calcium stearate, barium stearate, zinc stearate, calcium laurate, barium laurate, and zinc laurate; metal salts such as sodium, zinc, and barium of phenol and naphthol; organotin compounds such as dibutyltin dilaurate and dibutyltin dimaleate; and phosphites such as diethyl phosphate, dibutyl phosphate, dioctyl phosphate, diphenylisodecyl phosphate, tricresyl phosphate, triphenyl phosphate, tri(nonylphenyl) phosphate, and triisooctyl phosphate. In addition, examples of solvents such as xylene, naphtha, mineral oil, diisobutyl ketone, and butyl acetate, and suitable surfactants can be used as viscosity modifiers and diluents. Examples of flame retardants include antimony trioxide, red phosphorus, zinc borate, organic bromides, and chlorinated paraffins. Examples of colorants include aniline blue, phthalocyanine green, chrome yellow, titanium dioxide, and carbon black.

[0040] Furthermore, as the outer skin layer, in order to further enhance its appearance and texture, various patterns such as checkered patterns, granular patterns, diamond patterns, heart patterns, clover patterns, spade patterns, cow patterns, lizard patterns, snake patterns, crocodile patterns, tiger patterns, and leopard patterns can be applied. In addition, surface treatments such as enamel, gold and silver brocade, and gloss agents can be used.

[0041] When the synthetic leather paste of the present invention is used as a foaming layer material, especially due to its excellent softness and the absence of quality and hygiene problems such as leakage, it preferably contains 50 to 150 parts by weight of plasticizer, particularly preferably 70 to 130 parts by weight, and even more preferably 90 to 110 parts by weight, relative to 100 parts by weight of the vinyl chloride-vinyl acetate copolymer paste. Examples of plasticizers similar to those described above can be cited as examples.

[0042] Furthermore, when using the synthetic leather paste vinyl chloride of the present invention as a foaming layer material, 2 to 7 parts by weight of a foaming agent are preferably used relative to 100 parts by weight of the vinyl chloride-vinyl acetate copolymer paste; particularly preferably, 3 to 6 parts by weight; and even more preferably, 4 to 6 parts by weight. The foaming agent used can be a foaming agent commonly known for use with vinyl chloride resins, such as azodicarbonamide, azobisisobutyronitrile, benzenesulfonyl hydrazine, p-toluenesulfonyl hydrazine, p,p'-oxobis(benzenesulfonyl hydrazine), dinitrosopentamethylenetetramine, N,N'-dinitroso-N,N'-dimethylterephthalamide, trihydrazine triazine, etc. One of these foaming agents can be used, or two or more can be used in combination.

[0043] In addition, when making the foamed layer, it can be combined with other pigments, diluents, inorganic fillers, heat stabilizers, viscosity modifiers, colorants, flame retardants, etc.

[0044] Furthermore, the foam layer can be any type of foam layer, including single-foam layers and multi-foam layers. To achieve a superior balance between feel and durability in synthetic leather, the cells of the foam are preferably uniformly spaced, single-foam layers. Additionally, a foam layer with a foaming ratio of 2 to 10 times is preferred, and 3 to 7 times is even more preferred.

[0045] The base fabric (sometimes called the pre-fabricated material) is the material that supports the foam layer and, consequently, the outer layer. Any material used as the pre-fabricated material (base fabric) for general synthetic leather or artificial leather can be used, such as woven fabrics, woven cloths, and non-woven fabrics. Furthermore, examples of woven fabrics, woven cloths, and non-woven fabrics include materials composed of individual fibers or blends of synthetic fibers such as polyester, polyamide, polyacrylonitrile, and nylon; natural fibers such as cotton and linen; and regenerated fibers such as rayon and cellulose acetate.

[0046] As a method for manufacturing synthetic leather in this invention, any method can be used as long as it can produce synthetic leather consisting of at least an epidermis, a foam layer, and a base fabric. Examples include: methods that bond the epidermis, foam layer, and base fabric separately using adhesives, hot pressing, etc.; methods that fully utilize the properties of vinyl chloride sol to prepare vinyl chloride sol for the epidermis and vinyl chloride sol for the foam layer, layer them separately, layer the base fabric, and heat them to perform resinification / foaming, etc.

[0047] Furthermore, in preparing vinyl chloride sol for the skin layer and vinyl chloride sol for the foaming layer, methods can be used such as planetary mixers, kneaders, three-roll mills, Hobart mixers, disc mixers, dissolvers, pounders, ribbon mixers, and Henschel mixers to uniformly mix vinyl chloride sol, plasticizers, and foaming agents and other additives as needed. Additionally, during shaping, methods can be used such as scraping onto release paper using a doctor blade, reverse roller, forward roller (natural roll), floating knife, air knife, curtain flow, or blowing using a sprayer.

[0048] Because the synthetic leather of this invention has excellent softness and tactile feel, it can be used in a wide range of fields, including automotive interiors such as panels, dashboards, instrument panels, door panels, roof panels, and console boxes; furniture such as sofas, wardrobes, and sideboards; bags / pockets such as briefcases, storage bags, and handbags; footwear such as shoes and sandals; clothing such as jackets, coats, and sportswear; and stationery.

[0049] Example

[0050] The present invention will now be described in more detail through examples and comparative examples. However, the present invention is not limited to these examples.

[0051] The following illustrates the evaluation / determination methods used in the examples.

[0052] <Evaluation of Softness>

[0053] The softness of the synthetic leather obtained through the examples and comparative examples was evaluated based on the tactile feedback of a randomly selected group of people.

[0054] ○; The synthetic leather feels soft to the touch when held.

[0055] ×; The synthetic leather feels hard to the touch.

[0056] <Average Degree of Polymerization>

[0057] Determined based on JIS-K6721.

[0058] <Average content of vinyl acetate residue units>

[0059] 100 mg of vinyl chloride-vinyl acetate copolymer particles were mixed with 10 mg of potassium bromide, ground, shaped, and the sample was measured using an infrared spectrophotometer (Shimadzu Corporation, (trade name) FTIR-8100A). The average content (by weight%) of vinyl acetate residue units in the vinyl chloride-vinyl acetate copolymer was calculated based on the obtained spectrum using the following formula.

[0060] VAc content = (3.73 × B / A + 0.024) × 1.04

[0061] A: 1430cm -1 The Abs. value of the absorption peak near the CH plane caused by in-plane bending.

[0062] B: 1740cm -1 The Abs. value of the absorption peak near the C=O stretching.

[0063] <Determination of the distribution of vinyl acetate residue units>

[0064] The distribution of vinyl acetate residue units was determined by 2D-HPLC (two-dimensional HPLC).

[0065] Device: Agilent 1290 Infinity II series (manufactured by Agilent Technologies).

[0066] Detector: Evaporative Light Scattering Detector (ELSD) G4260B (manufactured by Agilent Technologies).

[0067] First Dimension (GPEC)

[0068] Chromatographic column: TSKgel ODS-80Ts (manufactured by Tosoh Corporation).

[0069] Column temperature: 40℃.

[0070] Mobile phase: Solution A: 50% MeOH aqueous solution

[0071] Solution B: Tetrahydrofuran

[0072] Flow rate: 0.6 ml / min.

[0073] Concentration: 1.0 mg / ml.

[0074] Injection volume: 20 μl.

[0075] Second Dimension (GPC)

[0076] Chromatographic column: TSKgel SuperAWM-H (manufactured by Tosoh Corporation).

[0077] Column temperature: 40℃.

[0078] Eluent: Tetrahydrofuran

[0079] Flow rate: 0.6 ml / min.

[0080] Quantitative ring capacity: 40 μl.

[0081] <Particle Size Distribution>

[0082] The synthetic leather paste vinyl chloride was dispersed in water and ultrasonically dispersed. The particle size distribution was measured using a disc centrifugal particle size distribution measuring device (LUFT Corporation, Japan, (trade name) DC24000UHR).

[0083] Synthesis example 1

[0084] In 1m 3 360 kg of deionized water, 300 kg of vinyl chloride monomer, 5.7 kg of lauroyl peroxide, and 30 kg of 15 wt% sodium dodecylbenzenesulfonate aqueous solution were added to a stainless steel high-pressure reactor. After homogenization using a homogenizer for 3 hours, the temperature of the reaction system was raised to 45°C to begin polymerization. After the pressure of the polymerization system was reduced, the unreacted vinyl chloride monomer was recovered, yielding a vinyl chloride resin seed latex (a) with a solid content of 35 wt%, an average particle size of 0.55 μm, and 2 wt% lauroyl peroxide content relative to the vinyl chloride resin.

[0085] Synthesis example 2

[0086] In 1m 3400 kg of deionized water, 300 kg of vinyl chloride monomer, 81 g of potassium persulfate, and 10 kg of 16 wt% potassium laurate aqueous solution were added to a stainless steel autoclave. The temperature of the reaction system was raised to 54 °C to begin polymerization. From the start to the end of polymerization, 0.7 parts by weight of 15 wt% sodium dodecylbenzenesulfonate aqueous solution was continuously added relative to the vinyl chloride monomer. After the pressure of the polymerization system was reduced, the unreacted vinyl chloride monomer was recovered, yielding a vinyl chloride resin seed latex (b) with a solid content of 40 wt% and an average particle size of 0.15 μm.

[0087] Example 1

[0088] In a 2.5-liter autoclave, 610 g of deionized water, 493 g of vinyl chloride monomer (62 wt% relative to the total amount of mixed monomers), 96 g of vinyl acetate monomer (12 wt% relative to the total amount of mixed monomers), 9 g of 5% sodium dodecyl sulfate aqueous solution, 85 g of seed latex (a) with an average particle size of 0.55 μm obtained by Synthesis Example 1, and 4 g of 0.1% copper sulfate aqueous solution were added. The temperature of the reaction mixture was then raised to 35°C to begin the first stage of polymerization, and 0.05 wt% ascorbic acid aqueous solution was continuously added throughout the polymerization time to maintain the polymerization temperature. When the polymerization conversion reached 50%, 140 g of vinyl chloride monomer (17 wt% relative to the total amount of mixed monomers) was added to the 2.5-liter autoclave as the second stage of polymerization, and the second stage of polymerization was continued at a polymerization temperature of 35°C.

[0089] Furthermore, when the polymerization conversion rate reaches 80% relative to the total of the monomers fed in the first and second stages, 70g of vinyl chloride monomer (9g by weight relative to the total amount of mixed monomers) is fed into a 2.5-liter autoclave as the monomer for the third stage. The third stage polymerization continues at a polymerization temperature of 35°C. When the polymerization conversion rate reaches 90% relative to the total of the mixed monomers, the polymerization ends.

[0090] During the polymerization process from start to finish, 0.7 parts by weight of a 5% sodium dodecyl sulfate aqueous solution and 0.1 parts by weight of a 10-molar adduct ammonium salt of nonylpropenylphenol ethylene oxide sulfate (Daiichi Kogyo Pharmaceutical Co., Ltd.: (trade name) Aqualon BC-1025) were continuously added relative to the vinyl chloride monomer to obtain a vinyl chloride-vinyl acetate copolymer latex.

[0091] One kilogram of the obtained vinyl chloride-vinyl acetate copolymer latex was spray-dried using a rotary disc spray dryer at a hot air temperature of 160°C and an outlet temperature of 60°C to obtain a synthetic leather paste vinyl chloride-vinyl acetate copolymer. The obtained synthetic leather paste vinyl chloride had a vinyl acetate residue unit content of 9.0 wt% and a degree of polymerization of 1,900. The results of the determination of the vinyl acetate residue unit content and particle size distribution are shown in Table 1.

[0092] Example 2

[0093] In a 2.5-liter autoclave, 610 g of deionized water, 501 g of vinyl chloride monomer (62 wt% relative to the total amount of mixed monomers), 82 g of vinyl acetate monomer (10 wt% relative to the total amount of mixed monomers), 9 g of 5% sodium dodecyl sulfate aqueous solution, 85 g of seed latex (a) with an average particle size of 0.55 μm obtained by Synthesis Example 1, and 4 g of 0.1% copper sulfate aqueous solution were added. The temperature of the reaction mixture was then raised to 40°C to begin the first stage of polymerization, and 0.05 wt% ascorbic acid aqueous solution was continuously added throughout the polymerization time to maintain the polymerization temperature. When the polymerization conversion reached 73%, 140 g of vinyl chloride monomer (17 wt% relative to the total amount of mixed monomers) was added to the 2.5-liter autoclave as the second stage of polymerization, and the second stage of polymerization was continued at a polymerization temperature of 35°C.

[0094] Furthermore, when the polymerization conversion rate reaches 82% relative to the total of the monomers fed in the first and second stages, 70g of vinyl chloride monomer (9g by weight relative to the total amount of mixed monomers) is fed into a 2.5-liter autoclave as the monomer for the third stage. The third stage polymerization continues at a polymerization temperature of 35°C. When the polymerization conversion rate reaches 90% relative to the total of the mixed monomers, the polymerization ends.

[0095] During the polymerization process from start to finish, 0.7 parts by weight of a 5% sodium dodecyl sulfate aqueous solution and 0.1 parts by weight of a 10-molar adduct ammonium salt of nonylpropenylphenol ethylene oxide sulfate (Daiichi Kogyo Pharmaceutical Co., Ltd.: (trade name) Aqualon BC-1025) were continuously added relative to the vinyl chloride monomer to obtain a vinyl chloride-vinyl acetate copolymer latex.

[0096] One kilogram of the obtained vinyl chloride-vinyl acetate copolymer latex was spray-dried using a rotary disc spray dryer at a hot air temperature of 160°C and an outlet temperature of 60°C to obtain a synthetic leather paste vinyl chloride-vinyl acetate copolymer. The obtained synthetic leather paste vinyl chloride had a vinyl acetate residue unit content of 6.6 wt% and a degree of polymerization of 1,810. The results of the determination of the vinyl acetate residue unit content and particle size distribution are shown in Table 1.

[0097] Example 3

[0098] In a 2.5-liter autoclave, 610 g of deionized water, 225 g of vinyl chloride monomer (26 wt% relative to the total amount of mixed monomers), 51 g of vinyl acetate monomer (6 wt% relative to the total amount of mixed monomers), 9 g of 5% sodium dodecylbenzenesulfonate aqueous solution, 90 g of seed latex (a) with an average particle size of 0.55 μm obtained by Synthesis Example 1, and 4 g of 0.1% copper sulfate aqueous solution were added. The temperature of the reaction mixture was then raised to 47°C to begin the first stage of polymerization, and 0.05 wt% ascorbic acid aqueous solution was continuously added throughout the polymerization time to maintain the polymerization temperature. When the polymerization conversion reached 85%, 250 g of vinyl chloride monomer (29 wt% relative to the total amount of mixed monomers) was added to the 2.5-liter autoclave as the second stage of polymerization, and the second stage of polymerization was continued at a polymerization temperature of 44°C.

[0099] Furthermore, when the polymerization conversion rate reaches 89% relative to the total of the monomers fed in the first and second stages, 331g of vinyl chloride monomer (39g by weight relative to the total amount of mixed monomers) is fed into a 2.5-liter autoclave as the monomer for the third stage. The third stage polymerization continues at a polymerization temperature of 40°C. When the polymerization conversion rate reaches 90% relative to the total of the mixed monomers, the polymerization ends.

[0100] During the polymerization process from start to finish, 0.7 parts by weight of a 5% by weight aqueous solution of sodium dodecylbenzenesulfonate was continuously added relative to the vinyl chloride monomer to obtain a vinyl chloride-vinyl acetate copolymer latex.

[0101] One kilogram of the obtained vinyl chloride-vinyl acetate copolymer latex was spray-dried using a rotary disc spray dryer at a hot air temperature of 160°C and an outlet temperature of 60°C to obtain a synthetic leather paste vinyl chloride-vinyl acetate copolymer. The obtained synthetic leather paste vinyl chloride had a vinyl acetate residue unit content of 4.8 wt% and a degree of polymerization of 1,650. The results of the determination of the vinyl acetate residue unit content and particle size distribution are shown in Table 1.

[0102] Example 4

[0103] In a 2.5-liter autoclave, 610 g of deionized water, 227 g of vinyl chloride monomer (28 wt% relative to the total amount of mixed monomers), 41 g of vinyl acetate monomer (5 wt% relative to the total amount of mixed monomers), 9 g of 5% sodium dodecylbenzenesulfonate aqueous solution, 90 g of seed latex (a) with an average particle size of 0.55 μm obtained by Synthesis Example 1, and 4 g of 0.1% copper sulfate aqueous solution were added. The temperature of the reaction mixture was then raised to 58°C to begin the first stage of polymerization, and 0.05 wt% ascorbic acid aqueous solution was continuously added throughout the polymerization time to maintain the polymerization temperature. When the polymerization conversion reached 86%, 227 g of vinyl chloride monomer (28 wt% relative to the total amount of mixed monomers) was added to the 2.5-liter autoclave as the second stage of polymerization, and the second stage of polymerization was continued at a polymerization temperature of 55°C.

[0104] Furthermore, when the polymerization conversion rate reaches 90% relative to the total of the monomers fed in the first and second stages, 300g of vinyl chloride monomer (38g by weight relative to the total amount of mixed monomers) is fed into a 2.5-liter autoclave as the monomer for the third stage. The third stage polymerization continues at a polymerization temperature of 51°C. The polymerization ends when the polymerization conversion rate reaches 90% relative to the total of the mixed monomers.

[0105] During the polymerization process from start to finish, 0.7 parts by weight of a 5% by weight aqueous solution of sodium dodecylbenzenesulfonate was continuously added relative to the vinyl chloride monomer to obtain a vinyl chloride-vinyl acetate copolymer latex.

[0106] One kilogram of the obtained vinyl chloride-vinyl acetate copolymer latex was spray-dried using a rotary disc spray dryer at a hot air temperature of 115°C and an outlet temperature of 55°C to obtain vinyl chloride paste for synthetic leather as a vinyl chloride-vinyl acetate copolymer paste. The obtained vinyl chloride paste for synthetic leather had a vinyl acetate residue unit content of 4.0 wt% and a degree of polymerization of 1,020. The results of the determination of the vinyl acetate residue unit content and particle size distribution are shown in Table 1.

[0107] Synthesis example 3

[0108] In a 2.5-liter autoclave, 610 g of deionized water, 420 g of vinyl chloride monomer (60 wt% of the total mixed monomers) as the first-stage feed monomer, 8 g of 5% sodium dodecyl sulfate aqueous solution, 85 g of seed latex (a) with an average particle size of 0.55 μm obtained by Synthesis Example 1, and 4 g of 0.1% copper sulfate aqueous solution were added. The temperature of the reaction mixture was then raised to 49°C to begin the first-stage polymerization, and 0.05 wt% ascorbic acid aqueous solution was continuously added throughout the polymerization time to maintain the polymerization temperature. When the polymerization conversion reached 88%, 280 g of vinyl chloride monomer (40 wt% of the total mixed monomers) as the second-stage feed monomer was added to the 2.5-liter autoclave, and the second-stage polymerization was continued at a polymerization temperature of 45°C. The polymerization was terminated when the total polymerization conversion relative to the mixed monomers reached 90%.

[0109] During the polymerization process from start to finish, 0.7 parts by weight of a 5% sodium dodecyl sulfate aqueous solution were continuously added relative to the vinyl chloride monomer to obtain a vinyl chloride polymer latex.

[0110] One kilogram of the obtained vinyl chloride polymer latex was spray-dried using a rotary disc spray dryer at a hot air temperature of 160°C and an outlet temperature of 60°C to obtain a vinyl chloride paste polymer. The degree of polymerization of the obtained vinyl chloride paste polymer was 1,660.

[0111] Synthesis example 4

[0112] In a 2.5L stainless steel autoclave, 610g of deionized water, 800g of vinyl chloride monomer, 10g of a 5% sodium sulfosuccinate aqueous solution, and 4 parts by weight of seed latex (a) with an average particle size of 0.55μm obtained by Synthesis Example 1 relative to 100 parts by weight of vinyl chloride monomer, and 1 part by weight of seed latex (b) with an average particle size of 0.15μm obtained by Synthesis Example 2 relative to 100 parts by weight of vinyl chloride monomer were added. The temperature of the reaction mixture was raised to 42°C to begin polymerization. From the start to the end of polymerization, 0.5 parts by weight of the 5% sodium sulfosuccinate aqueous solution was continuously added relative to the vinyl chloride monomer. When the polymerization pressure decreased from the saturated vapor pressure of the vinyl chloride monomer at 42°C to 0.30MPa, polymerization was stopped, and unreacted vinyl chloride monomer was recovered to obtain a vinyl chloride polymer latex.

[0113] One kilogram of the obtained vinyl chloride polymer latex was spray-dried using a rotary disc spray dryer at a hot air temperature of 160°C and an outlet temperature of 60°C to obtain a vinyl chloride paste polymer. The degree of polymerization of the obtained vinyl chloride paste polymer was 2,120.

[0114] Synthesis example 5

[0115] In a 2.5L stainless steel autoclave, 610g of deionized water, 730g of vinyl chloride monomer, 15g of a 5% sodium dodecylbenzenesulfonate aqueous solution, and 4 parts by weight of seed latex with an average particle size of 0.55μm obtained from Synthesis Example 1 (a) relative to 100 parts by weight of vinyl chloride monomer, and 5 parts by weight of seed latex with an average particle size of 0.15μm obtained from Synthesis Example 2 (b) relative to 100 parts by weight of vinyl chloride monomer were added. The temperature of the reaction mixture was raised to 54°C, and polymerization was started. From the start to the end of polymerization, 0.7 parts by weight of a 5% sodium dodecyl sulfate aqueous solution was continuously added relative to the vinyl chloride monomer. Polymerization was stopped when the polymerization pressure decreased from the saturated vapor pressure of vinyl chloride monomer at 54°C to 0.35MPa, and unreacted vinyl chloride monomer was recovered to obtain a vinyl chloride polymer latex.

[0116] One kilogram of the obtained vinyl chloride polymer latex was spray-dried using a rotary disc spray dryer at a hot air temperature of 160°C and an outlet temperature of 60°C to obtain a paste vinyl chloride polymer. The obtained paste vinyl chloride polymer did not contain sodium dodecyl sulfate, nonylpropenylphenol ethylene oxide 10 molar adduct ammonium sulfate, or other compounds. Furthermore, the degree of polymerization was 1,120. The results of the determination of the vinyl acetate residue unit content and particle size distribution are shown in Table 1.

[0117]

[0118] Example 5

[0119] In contrast to 100 parts by weight of the synthetic leather paste vinyl chloride obtained by Example 1, 60 parts by weight of DINP (manufactured by J-PLUS Corporation) as a plasticizer and 3 parts by weight of calcium-zinc composite heat stabilizer (manufactured by ADEKA Corporation, (grade name) SC-320) were added, and the mixture was kneaded using a solvent to prepare a vinyl chloride paste for the outer layer.

[0120] Compared to 100 parts by weight of the vinyl chloride paste obtained by Synthesis Example 5, 100 parts by weight of DINP (manufactured by J-PLUS Co., Ltd.) as a plasticizer, 50 parts by weight of calcium carbonate ((trade name) NN#500, manufactured by Nitto Powdered Chemical Co., Ltd.), 4 parts by weight of titanium dioxide (Tayca Co., Ltd., trade name JR600A) as a pigment, 5 parts by weight of foaming agent (Otsuka Chemical Co., Ltd., trade name AZ ULTRA 1050), and 1.6 parts by weight of stabilizer (Asahi Denka Co., Ltd., trade name FL103N) were added, and the mixture was kneaded using a solvent to prepare a vinyl chloride paste for foaming layer.

[0121] However, on a release paper that has been preheated to 180°C for 5 seconds, a vinyl chloride sol paste for the outer layer is applied to a thickness of 0.2 mm. After heating at 180°C for 10 seconds to obtain the original film 1, a vinyl chloride sol paste for the foaming layer is applied to the original film 1 to a thickness of 0.2 mm. After heating at 200°C for 6 seconds to obtain the original film 2, a knitted fabric is bonded to the foaming layer as the base fabric. The fabric is then heated at 200°C for 90 seconds to gel (resinize) and foam. The release paper is then peeled off, thereby obtaining synthetic leather with a single foamed layer as the foaming layer.

[0122] The evaluation results of the obtained synthetic leather are shown in Table 2. The obtained synthetic leather is soft and has an excellent feel.

[0123] Examples 6-8

[0124] The synthetic leather paste vinyl chloride obtained in Examples 2, 3, and 4 was used instead of the synthetic leather paste vinyl chloride obtained in Example 1 as the vinyl chloride sol for the epidermal layer. Otherwise, synthetic leather with a single foam layer as the foaming layer was obtained by the same method as in Example 5, and it was evaluated.

[0125] The evaluation results are shown in Table 2. The obtained synthetic leather is soft and has an excellent feel.

[0126] Example 9

[0127] The vinyl chloride sol for the foaming layer was obtained by replacing the vinyl chloride sol obtained in Synthetic Example 5 with the vinyl chloride sol obtained in Example 1. Otherwise, synthetic leather with a single-foam layer was obtained using the same method as in Example 5, and its quality was evaluated. The evaluation results are shown in Table 2. The obtained synthetic leather is soft and has an excellent feel.

[0128] Example 10

[0129] The plasticizer in the vinyl chloride sol paste used for the outer layer was changed to 80 parts by weight. Otherwise, synthetic leather was obtained using the same method as in Example 5 and evaluated. The evaluation results are shown in Table 2. The obtained synthetic leather is soft and has an excellent feel.

[0130] Example 11

[0131] The plasticizer in the vinyl chloride sol used for the foaming layer was changed to 120 parts by weight. Otherwise, synthetic leather was obtained using the same method as in Example 5 and evaluated. The evaluation results are shown in Table 2. The obtained synthetic leather is soft and has an excellent feel.

[0132]

[0133] Comparative Examples 1-2

[0134] The sol used for the epidermis layer was replaced with the vinyl chloride paste polymer obtained by Synthetic Examples 3 and 4, instead of the vinyl chloride paste for synthetic leather obtained by Example 1. Otherwise, synthetic leather was obtained by the same method as in Example 5 and evaluated.

[0135] The evaluation results are shown in Table 3. The resulting synthetic leather lacks softness and has a poor tactile feel.

[0136] Comparative Example 3

[0137] The sol used for the epidermis layer was obtained by replacing the vinyl chloride paste obtained in Example 1 with the vinyl chloride paste obtained in Example 3, and the plasticizer of the sol used for the epidermis layer was changed to 80 parts by weight. Otherwise, synthetic leather was obtained by the same method as in Example 5 and evaluated.

[0138] The evaluation results are shown in Table 3. The resulting synthetic leather lacks softness and has a poor tactile feel.

[0139] Comparative Example 4

[0140] The sol used for the outer layer was obtained by replacing the vinyl chloride paste obtained in Example 1 with the vinyl chloride paste obtained in Example 3. The plasticizer in the sol used for the outer layer was changed to 80 parts by weight, and the plasticizer in the sol used for the foam layer was changed to 120 parts by weight. Otherwise, synthetic leather was obtained by the same method as in Example 5 and evaluated.

[0141] The evaluation results are shown in Table 3. The resulting synthetic leather lacks softness and has a poor tactile feel.

[0142]

[0143] It should be noted that the entire contents of the claims, description and abstract of Japanese Patent Application No. 2023-105601 filed on June 28, 2023 and Japanese Patent Application No. 2024-058761 filed on April 1, 2024 are incorporated herein as a disclosure of the specification of this invention.

[0144] Industrial applicability

[0145] The synthetic leather paste of the present invention provides synthetic leather with excellent softness and feel, which can be used in various industries and has very high industrial value.

Claims

1. A synthetic leather paste-type vinyl chloride resin, which is a vinyl chloride-vinyl acetate copolymer containing 3-15% by weight of vinyl acetate residue units and having an average degree of polymerization of 900-2,200.

2. The vinyl chloride resin for synthetic leather as described in claim 1, wherein, The distribution of vinyl acetate residue unit content shows a continuous distribution with one maximum and a mode of 1 to 30% by weight. The particle size of the largest peak showing the cumulative weight frequency in the primary particle size ranges from 0.1 to 5 μm.

3. A synthetic leather comprising a vinyl chloride-vinyl acetate copolymer containing 3 to 15% by weight of vinyl acetate residue units and having an average degree of polymerization of 900 to 2,200.

4. The synthetic leather according to claim 3, wherein it is formed of at least an epidermis layer, a foam layer, and a base fabric, wherein, The skin layer and / or foam layer contain a vinyl chloride-vinyl acetate copolymer containing 3 to 15% by weight of vinyl acetate residue units and having an average degree of polymerization of 900 to 2,200.

5. The synthetic leather according to claim 4, wherein, The skin layer contains 40 to 100 parts by weight of a vinyl chloride-vinyl acetate copolymer paste containing 3 to 15% by weight of vinyl acetate residue units and having an average degree of polymerization of 900 to 2,200.

6. The synthetic leather according to claim 4, wherein, The foam layer contains 50-150 parts by weight of plasticizer relative to 100 parts by weight of a vinyl chloride-vinyl acetate copolymer paste containing 3-15% by weight of vinyl acetate residue units and having an average degree of polymerization of 900-2,200.

7. The synthetic leather according to claim 5 or 6, wherein, The plasticizer is selected from at least one plasticizer selected from diisononyl phthalate, bis(2-ethylhexyl) terephthalate, diisodecyl phthalate, dibutyl phthalate, (2-ethylhexyl) adipate, diisononyl adipate, tri(2-ethylhexyl) trimellitate and triisodecyl trimellitate.

8. A method for manufacturing synthetic leather, the method comprising layering an outer skin layer, a foam layer, and a base fabric. in, The skin layer and the foam layer have undergone paste processing. At this time, the vinyl chloride sol paste used for the skin layer and / or the vinyl chloride sol paste used for the foam layer contains vinyl chloride-vinyl acetate copolymer paste and plasticizer. The vinyl chloride-vinyl acetate copolymer paste contains 3 to 15% by weight of vinyl acetate residue units and has an average degree of polymerization of 900 to 2200.

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