Aqueous adhesive composition

Abstract

To provide an aqueous adhesive composition in which maintenance of adhesiveness over a wide temperature range and improvement of water resistance are achieved.SOLUTION: An aqueous adhesive composition for forming an adhesive layer on a surface of a cloth transport member of an ink jet printing apparatus comprises a (meth)acrylic-based resin, a pH adjuster, and water, where the (meth)acrylic-based resin comprises, as constituent units, at least four types of (meth)acrylate units A and at least one type of (meth)acrylic acid unit B; the (meth)acrylic-based resin has a glass transition temperature of -25°C to -8°C; and a difference in glass transition temperature between a maximum value and a minimum value among homopolymers formed from the respective constituent units is 170°C or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aqueous pressure-sensitive adhesive composition. [Background technology]

[0002] Inkjet recording methods are capable of recording high-resolution images using relatively simple devices, and have been rapidly developing in various fields. In the process, various studies have been conducted on ejection stability, etc. For example, Patent Document 1 discloses, as a textile printing technology using an inkjet system, a conveying device and an image recording device that are equipped with a displacement suppressing member for a conveying member, with the aim of stabilizing the contact state between a removal member and a conveying member and improving the recovery performance of cleaning water by the removal member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-109036 Summary of the Invention [Problem to be solved by the invention]

[0004] As shown in Patent Document 1, in inkjet printing technology, a fabric is attached to a transport member such as an endless belt and transported to a printing unit. An adhesive is applied to the surface of the transport member, making the surface of the transport member sticky. The adhesive is also called a backing agent.

[0005] After printing, the cloth that serves as the recording medium is peeled off from the transport member and transported to the next process. However, since the cloth will be reattached to the transport member after the peeling, it is necessary to remove ink, lint, and other remaining materials that have adhered to the transport member during the printing process. Usually, the remaining materials adhering to the transport member are washed away with water. In this case, brushes, sponges, etc. may be used to clean the transport member.

[0006] The adhesives used in such inkjet printing are generally those in which a hydrophobic resin is dissolved in an organic solvent so as to be resistant to water washing. Recently, however, there has been a demand for water-based adhesives that use less organic solvent in order to reduce environmental impact and improve the working environment. However, water-based adhesives are inferior in durability and water resistance, and the adhesiveness of the adhesive applied to the surface of the conveying member tends to gradually decrease with washing, resulting in the need to apply new adhesive after each washing.

[0007] Furthermore, adhesives used in ink-jet printing are also required to maintain adhesiveness over a wide temperature range and to have improved durability and water resistance. [Means for solving the problem]

[0008] The aqueous adhesive composition of the present invention is an aqueous adhesive composition for forming an adhesive layer on the surface of a fabric transport member of an inkjet printing device, and comprises a (meth)acrylic resin, a pH adjuster, and water, wherein the (meth)acrylic resin comprises, as structural units, four or more types of (meth)acrylate units A and one or more types of (meth)acrylic acid units B, the (meth)acrylic resin has a glass transition temperature of -25 to -8°C, and the difference between the maximum and minimum glass transition temperatures of homopolymers constituted by each of the structural units is 170°C or more.

[0009] The method for imparting tackiness of the present invention comprises a step of adhering the aqueous pressure-sensitive adhesive composition to the surface of a fabric transport member of an ink-jet textile printing apparatus to form a pressure-sensitive adhesive layer.

[0010] The inkjet printing device of the present invention includes a conveying mechanism that conveys a fabric by adhering it to an adhesive layer made of the above-mentioned aqueous adhesive composition formed on the surface of a fabric conveying member, a recording unit that performs textile printing recording on the fabric adhered to the adhesive layer using an inkjet head, and a cleaning unit that cleans the adhesive layer from which the fabric has been peeled off after the textile printing recording.

[0011] The fabric transport member of the ink-jet printing apparatus of the present invention has, on its surface, an adhesive layer derived from the aqueous adhesive composition.

[0012] The inkjet textile printing method of the present invention includes a transporting step of transporting a fabric by adhering it to an adhesive layer made of the aqueous adhesive composition formed on the surface of a fabric transport member of an inkjet textile printing device; a recording step of performing textile printing recording on the fabric adhered to the adhesive layer using an inkjet head; and a cleaning step of cleaning the adhesive layer from which the fabric has been peeled off after the textile printing recording. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic cross-sectional view of an inkjet textile printing apparatus. [Figure 2] 1 is a table showing examples and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to this, and various modifications are possible without departing from the spirit of the present invention. In the drawings, the same elements are given the same reference numerals, and redundant explanations will be omitted. Furthermore, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0015] The term "(meth)acrylate" is a comprehensive expression that encompasses acrylate and methacrylate. Furthermore, the term "unit" as in "structural unit" or "(meth)acrylate unit" refers to a repeating unit derived from a monomer when the monomer is polymerized to form a polymer.

[0016] 1. Water-based adhesive composition The aqueous adhesive composition according to this embodiment is a composition for forming an adhesive layer on the surface of a fabric transport member of an inkjet printing apparatus, and comprises a (meth)acrylic resin, a pH adjuster, and water, wherein the (meth)acrylic resin comprises, as structural units, four or more types of (meth)acrylate units A and one or more types of (meth)acrylic acid units B, the (meth)acrylic resin has a glass transition temperature of −25 to −8°C, and the difference between the maximum and minimum glass transition temperatures of homopolymers constituted by each of the structural units is 170°C or more.

[0017] In this specification, the term "fabric" refers to fibers in the form of woven fabric, knitted fabric, nonwoven fabric, etc. In conventional inkjet printing devices, an adhesive layer is formed on a transport member such as an endless belt, and the fabric serving as a recording medium is attached to the adhesive layer. The fabric is then transported to a printing unit, and after recording, the transport member and the fabric are peeled off.

[0018]

[0003] Conventionally, solvent-based acrylic adhesives have been widely used as adhesives for such fabric transport members. However, solvent-based acrylic adhesives volatilize organic solvents during application, raising concerns about adverse effects on the human body in the working environment. Furthermore, when using solvent-based acrylic adhesives, an exhaust system must be installed in the operating environment of the inkjet printing device, which increases the overall device configuration and increases costs.

[0019] On the other hand, in order to apply an adhesive to a fabric transport member of an inkjet printing device to form an adhesive layer and transport the fabric by adhering it to the adhesive layer, the adhesive layer must have adequate adhesive strength to adhere and peel the fabric, while also having durability, water resistance, and mechanical strength to withstand washing with water or brushing to remove lint and ink adhering to the adhesive layer. However, adhesive layers made with water-based adhesives tend to have poor water resistance, such as whitening over time, and poor mechanical strength, such as peeling. Furthermore, as shown in Figure 1, when applied to the surface of a fabric transport member, adhesive layers made with water-based adhesives tend to be unable to maintain their adhesive properties and to have poor durability as adhesives as the fabric transport distance increases. Therefore, it has been difficult to form an adhesive layer made with a water-based adhesive that has excellent water resistance, adhesive strength, and mechanical strength.

[0020] In general, the adhesive performance of adhesives is affected to a certain extent by temperature. If the adhesiveness decreases or increases, the fabric transportability decreases, and there is a risk of the fabric clogging in the printing equipment. Therefore, adhesives used in inkjet printing are required to maintain their adhesiveness over a wide temperature range.

[0021] To address the above-mentioned problems, the aqueous pressure-sensitive adhesive composition of the present embodiment contains a predetermined (meth)acrylic resin, a pH adjuster, and water. This allows the composition to have improved water resistance and mechanical strength while maintaining adhesiveness over a wide temperature range. Each component contained in the aqueous pressure-sensitive adhesive composition will be described in detail below.

[0022] 1.1.(Meth)acrylic resin By including a specific (meth)acrylic resin, the adhesive layer formed on the fabric conveying member has improved adhesive strength and water resistance, and maintains adhesiveness over a wide temperature range. The (meth)acrylic resin may be a water-soluble resin or a resin emulsion dispersed in an aqueous catalyst. These are collectively referred to as (meth)acrylic resins in this embodiment. The use of a (meth)acrylic resin can reduce the environmental burden caused by organic solvents, and also tends to further improve the peelability of the fabric from the adhesive layer.

[0023] The (meth)acrylic resin contains four or more types of (meth)acrylate units A and one or more types of (meth)acrylic acid units B as constituent units.

[0024] The (meth)acrylate unit A is not particularly limited, but preferably contains, for example, a structural unit derived from one or more monomers selected from the group consisting of methyl methacrylate (MMA), ethyl methacrylate (EMA), butyl methacrylate (BMA), butyl acrylate (BA), and 2-ethylhexyl acrylate (2EHA). By using such a (meth)acrylate unit A, the adhesive layer formed on the fabric conveying member tends to have improved adhesive durability, water resistance, and mechanical strength, and the adhesiveness tends to be maintained over a wide temperature range.

[0025] Among these, it is preferable that the four or more (meth)acrylate units A include a structural unit derived from butyl acrylate and a structural unit derived from butyl methacrylate, and that the structural unit derived from butyl acrylate and the structural unit derived from butyl methacrylate are the structural units with the highest and second highest content, respectively. The structural unit derived from butyl acrylate may be the structural unit with the highest content, or the structural unit derived from butyl methacrylate may be the structural unit with the highest content. This further improves the durability of the adhesive force, water resistance, and mechanical strength of the adhesive layer formed on the fabric conveying member, and also tends to maintain adhesiveness over a wide temperature range.

[0026] The content of the structural unit derived from butyl acrylate is preferably 20 to 35 mass%, 15 to 40 mass%, 10 to 45 mass%, or 5 to 50 mass%, relative to the total amount of the (meth)acrylic resin, which further improves the durability of the adhesive force, water resistance, and mechanical strength of the adhesive layer formed on the fabric conveying member, and also tends to maintain adhesiveness over a wide temperature range.

[0027] The content of the structural unit derived from butyl methacrylate, relative to the total amount of the (meth)acrylic resin, is preferably 45 to 55 mass%, 40 to 57.5 mass%, 35 to 60 mass%, 30 to 62.5 mass%, 25 to 65 mass%, or 20 to 67.5 mass%, thereby further improving the durability of the adhesive force, water resistance, and mechanical strength of the adhesive layer formed on the fabric conveying member, and also tends to better maintain adhesiveness over a wide temperature range.

[0028] The content of the (meth)acrylic acid unit A is preferably 97 to 99.9 mass%, 97.5 to 99.7 mass%, or 98 to 99.5 mass% relative to the total amount of the (meth)acrylic resin. When the content of the (meth)acrylic acid unit A is 97 mass% or more, water resistance and mechanical strength tend to be further improved. Furthermore, when the content of the (meth)acrylic acid unit A is 99.9 mass% or less, the durability of the adhesive force of the adhesive layer formed on the fabric conveying member tends to be further improved.

[0029] The (meth)acrylate units A preferably contain two or more types of (meth)acrylate units A1 having a glass transition temperature of 15° C. or higher and two or more types of (meth)acrylate units A2 having a glass transition temperature of −50° C. or lower. By containing (meth)acrylate units A1 having a relatively high glass transition temperature and (meth)acrylate units A2 having a relatively low glass transition temperature, the adhesive layer formed on the fabric conveying member tends to have improved adhesive durability, water resistance, and mechanical strength, and the adhesiveness tends to be maintained over a wide temperature range.

[0030] The (meth)acrylate units A1 are not particularly limited, and examples thereof include butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). The content of the (meth)acrylate units A1 is preferably 35 to 75 mass%, 45 to 70 mass%, or 50 to 65 mass% relative to the total amount of the (meth)acrylic resin. When the content of the (meth)acrylate units A1 is within the above range, the adhesive layer formed on the fabric conveying member has improved adhesive durability, water resistance, and mechanical strength, and the adhesiveness tends to be maintained over a wide temperature range.

[0031] The (meth)acrylate units A2 are not particularly limited, and examples thereof include methyl methacrylate (MMA), ethyl methacrylate (EMA), and butyl methacrylate (BMA). The content of the (meth)acrylate units A2 is preferably 25 to 65% by mass, 30 to 55% by mass, or 35 to 50% by mass, relative to the total amount of the (meth)acrylic resin. When the content of the (meth)acrylate units A2 is within the above range, the adhesive layer formed on the fabric conveying member has improved adhesive durability, water resistance, and mechanical strength, and the adhesiveness tends to be maintained over a wide temperature range.

[0032] The (meth)acrylic acid unit B is not particularly limited, but examples thereof include acrylic acid (AA) and methacrylic acid (MA).

[0033] The content of the (meth)acrylic acid unit B is preferably 0.1 to 3.0 mass%, 0.3 to 2.5 mass%, or 0.5 to 2.0 mass%, relative to the total amount of the (meth)acrylic resin. When the content of the (meth)acrylic acid unit B is 0.1 mass% or more, the durability of the adhesive force of the adhesive layer formed on the fabric conveying member tends to be further improved. Furthermore, when the content of the (meth)acrylic acid unit B is 3.0 mass% or less, the water resistance and mechanical strength tend to be further improved.

[0034] The difference between the maximum and minimum glass transition temperatures of the homopolymers constituted by each of the above structural units is 170° C. or more, preferably 170 to 250° C., and 172 to 225° C. When the difference between the maximum and minimum glass transition temperatures of the homopolymers constituted by each of the structural units is 170° C. or more, the adhesive force, durability, and mechanical strength of the adhesive layer formed on the fabric conveying member are further improved, and the adhesiveness tends to be maintained over a wide temperature range.

[0035] For example, consider a (meth)acrylic resin containing methyl methacrylate (MMA), ethyl methacrylate (EMA), butyl methacrylate (BMA), butyl acrylate (BA), and 2-ethylhexyl acrylate (2EHA) as (meth)acrylate units A, and acrylic acid (AA) as (meth)acrylic acid units B. In this case, the homopolymer with the highest glass transition temperature is acrylic acid (AA), with a glass transition temperature of 106°C. Furthermore, the homopolymer with the lowest glass transition temperature is 2-ethylhexyl acrylate (2EHA), with a glass transition temperature of -70°C. Therefore, the difference between the maximum and minimum glass transition temperatures in this case is 176°C.

[0036] The glass transition temperature of the (meth)acrylic resin is −25 to −8° C., preferably −21 to −9° C., and more preferably −18 to −10° C. When the glass transition temperature of the (meth)acrylic resin is −25° C. or higher, the adhesive strength durability of the adhesive layer formed on the fabric conveying member tends to be further improved. Furthermore, when the glass transition temperature of the (meth)acrylic resin is −8° C. or lower, the adhesiveness tends to be better maintained over a wide temperature range.

[0037] In the present embodiment, the glass transition temperature can be measured by a conventionally known method such as differential scanning calorimetry (DSC). The glass transition temperature of the (meth)acrylic resin can be adjusted by the homopolymer glass transition temperature of the polymerizable compound used and the mass ratio of the polymerizable compound used.

[0038] The content of the (meth)acrylic resin is preferably 30 to 70 mass%, 35 to 65 mass%, 40 to 60 mass%, or 45 to 55 mass% relative to the total amount of the aqueous pressure-sensitive adhesive composition. When the content of the (meth)acrylic resin is within the above range, the adhesive layer formed on the fabric conveying member has improved adhesive durability, water resistance, and mechanical strength, and the adhesiveness tends to be maintained over a wide temperature range. The content relative to the total amount of the aqueous pressure-sensitive adhesive composition refers to the amount of solids.

[0039] The aqueous pressure-sensitive adhesive composition may contain a resin other than the (meth)acrylic resin. Such other resins are not particularly limited, but examples thereof include urethane resins.

[0040] 1.2. pH adjusters The pH adjuster is not particularly limited, but examples thereof include inorganic acids (e.g., sulfuric acid, hydrochloric acid, nitric acid, etc.), inorganic bases (e.g., lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, ammonium salts, etc.), organic bases (triethanolamine, diethanolamine, monoethanolamine, tripropanolamine), and organic acids (e.g., adipic acid, citric acid, succinic acid, etc.).

[0041] Among these, ammonia or ammonium salts are preferred. By using such a pH adjuster, ammonia volatilizes when forming the adhesive layer, and the (meth)acrylic resins become more easily adhered to each other, forming a coating film that is less susceptible to water penetration. As a result, the adhesive layer formed on the fabric conveying member has improved adhesive strength durability and water resistance, and tends to maintain its adhesiveness over a wide temperature range.

[0042] Furthermore, when the surface of the fabric transport member has a urethane resin, the action of ammonia or ammonium salt tends to further improve the adhesion between the (meth)acrylic resin and the urethane resin, and also to further improve the mechanical strength.

[0043] The content of the pH adjuster is preferably 0.05 to 1.50 mass%, 0.10 to 1.00 mass%, 0.15 to 0.50 mass%, or 0.20 to 0.30 mass%, relative to the total amount of the aqueous pressure-sensitive adhesive composition. When the content of the pH adjuster is within the above range, the adhesive layer formed on the fabric conveying member has improved adhesive durability and water resistance, and the adhesiveness tends to be better maintained over a wide temperature range.

[0044] 1.3.Water The water content is preferably 30 to 80 mass %, 35 to 70 mass %, or 40 to 60 mass %, relative to the total amount of the aqueous pressure-sensitive adhesive composition.

[0045] 1.4.Surfactants The aqueous pressure-sensitive adhesive composition may contain a surfactant. The surfactant is not particularly limited, but examples thereof include anionic surfactants, nonionic surfactants, and cationic surfactants.

[0046] Examples of anionic surfactants include alkyl sulfocarboxylates, alkyl diphenyl ether disulfonates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, N-acylamino acids and their salts, N-acylmethyl taurines, alkyl sulfates such as ammonium lauryl sulfate and sodium lauryl sulfate, alkyl sulfate polyoxyalkyl ether sulfates, alkyl sulfate polyoxyethylene alkyl ether phosphates, rosin acid soap, castor oil sulfate, lauryl alcohol sulfate, alkyl phenol phosphates, alkyl phosphates, alkylaryl sulfonates, diethyl sulfosuccinate, diethylhexyl sulfosuccinate, and dioctyl sulfosuccinate. Commercially available anionic surfactants include, but are not limited to, EMALE 2FG, EMALE TD, RAMTEL AD25 (trade name, manufactured by Kao Corporation), MONOGEN Y100, MONOGEN Y500T, and HI-TENOL LA12 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

[0047] Examples of nonionic surfactants include acetylene glycol surfactants, silicone surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene hydrogenated castor oil, propylene glycol fatty acid esters, glycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, alkyl polyglycosides, alkyl diethanolamides, and alkylamine oxides.Commercially available nonionic surfactants include, but are not limited to, Emulgen 123P, 430, and 1108 (product names of Kao Corporation), Newcol 1006, 1008, and 1020 (product names of Nippon Nyukazai Co., Ltd.), Noigen DL-0415, ET-116B, ET-106A, DH-0300, YX-400, and EA-160 (product names of Daiichi Kogyo Seiyaku Co., Ltd.).

[0048] Examples of cationic surfactants include alkylamine salts, fatty acid amidoamine salts, monoalkyl quaternary ammonium salts, dialkyl quaternary ammonium salts, trialkyl quaternary ammonium salts, benzalkonium quaternary ammonium salts, benzethonium chloride, and alkylpyridinium salts.

[0049] In this embodiment, among these, nonionic surfactants are preferred, and more specifically, alkyl ether-based nonionic surfactants are preferred. They are even more preferred when used in combination with an anionic surfactant. Use of such surfactants tends to maintain durability and water resistance.

[0050] The content of the surfactant is preferably 1 to 7 mass %, 2 to 6 mass %, or 3 to 5 mass % relative to the total amount of the aqueous pressure-sensitive adhesive composition.

[0051] 1.5. Tackifiers The aqueous pressure-sensitive adhesive composition preferably contains no or a small amount of a tackifier. When the aqueous pressure-sensitive adhesive composition contains no or a small amount of a tackifier, the adhesive strength of the adhesive layer and the effect of suppressing the decrease in adhesive strength during brushing tend to be more sustained. Typical examples of such tackifiers include rosin-based compounds, terpene-based compounds, and hydrocarbon resins. More specifically, examples of the compound include rosin-based compounds such as natural rosin, modified rosin, glycerol esters of natural rosin, glycerol esters of modified rosin, pentaerythritol esters of natural rosin, and pentaerythritol esters of modified rosin; terpene-based compounds such as copolymers of natural terpene, three-dimensional polymers of natural terpene, aromatic modified terpene resins, hydrogenated derivatives of aromatic modified terpene resins, terpene phenol resins, and terpene resins (monoterpene, diterpene, triterpene, polyperene, etc.); and hydrocarbon resins such as aliphatic petroleum hydrocarbon resins (C5 resins), hydrogenated derivatives of aliphatic petroleum hydrocarbon resins, aromatic petroleum hydrocarbon resins (C9 resins) such as styrene oligomers, and hydrogenated derivatives of aromatic petroleum hydrocarbon resins.

[0052] It is preferable that the composition does not contain a tackifier. However, if a tackifier is contained, the content thereof is preferably 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, or 1% by mass or less, based on the total amount of the aqueous pressure-sensitive adhesive composition. When the content of the tackifier is within the above range, the adhesive strength of the resulting adhesive layer and the effect of suppressing a decrease in adhesive strength during brushing tend to be more sustained. From the same viewpoint, the total content of compounds selected from the group consisting of rosin-based compounds, terpene-based compounds, and hydrocarbon resins is also preferably within the same range.

[0053] 1.6. Organic Solvents From the viewpoint of reducing environmental impact and human health impact, the aqueous pressure-sensitive adhesive composition of the present embodiment preferably does not contain any organic solvents that are subject to the Organic Solvent Poisoning Prevention Regulations (hereinafter referred to as the Organic Solvent Regulations) established by the Ministry of Health, Labor and Welfare of Japan, and more preferably does not contain any organic solvents, including those not subject to the Organic Solvent Regulations. Furthermore, when an organic solvent is contained, the content of the organic solvent is preferably 5.0 mass% or less, 2.5 mass% or less, or 1.0 mass% or less, based on the total amount of the aqueous pressure-sensitive adhesive composition. This reduces the environmental impact and VOCs (volatile organic compounds) emitted when the aqueous pressure-sensitive adhesive composition is used, which tends to further improve the working environment.

[0054] 1.7.Colorants The aqueous pressure-sensitive adhesive composition of this embodiment preferably does not contain a colorant. Furthermore, if a colorant is contained, the content of the colorant is preferably 1.0 mass % or less, 0.5 mass % or less, or 0.3 mass % or less, based on the total amount of the aqueous pressure-sensitive adhesive composition. This clearly distinguishes the aqueous pressure-sensitive adhesive composition of this embodiment from compositions intended for coloring ink compositions, textile printing pastes, paints, and the like.

[0055] 2.Method of providing adhesiveness The method for imparting tackiness of this embodiment includes a step of adhering the aqueous pressure-sensitive adhesive composition to the surface of a fabric transport member of an inkjet textile printing apparatus to form a pressure-sensitive adhesive layer.

[0056] The step of forming the adhesive layer is a step of applying the aqueous adhesive composition to the surface of the fabric conveying member to form an adhesive layer. The method of applying the aqueous adhesive composition to the fabric conveying member is not particularly limited, but the aqueous adhesive composition may be applied uniformly to the entire surface of the fabric conveying member using a blade or the like, or may be applied to a part of the surface of the fabric conveying member in a predetermined pattern.

[0057] In the adhesive layer-forming step, the aqueous adhesive composition may be dried to form the adhesive layer. The drying temperature is preferably 10 to 60°C, and more preferably 20 to 40°C. The drying time is preferably 1 to 24 hours, and more preferably 2 to 8 hours. This tends to further improve the water resistance and mechanical strength of the resulting adhesive layer.

[0058] 3. Inkjet printing equipment The inkjet printing apparatus of this embodiment has a conveying mechanism that conveys a fabric by adhering it to an adhesive layer made of the above-mentioned aqueous adhesive composition formed on the surface of a fabric conveying member, a recording unit that performs textile printing recording on the fabric adhered to the adhesive layer using an inkjet head, and a cleaning unit that cleans the adhesive layer from which the fabric has been peeled off after textile printing recording.

[0059] An inkjet textile printing apparatus 100 of this embodiment will be described with reference to Figure 1. Figure 1 is an overall configuration diagram of the inkjet textile printing apparatus 100 including a conveying device 200 of this embodiment. In Figure 1, arrows a and b indicate the conveying direction of the recording medium 300. Arrows c and d indicate the rotation direction of the fabric conveying member 210. Arrows e and f indicate the rotation direction of the conveying rollers 221 and 222.

[0060] The inkjet printing apparatus 100 may include a conveying device 200 for adhering a recording medium to a surface and conveying it, recording medium conveying rollers 111 and 112, and a recording unit 120. A recording medium 300 coming from the direction a is pressed against a fabric conveying member 210 by the recording medium conveying roller 111, and the recording medium 300 is adhered to the surface of the fabric conveying member 210.

[0061] With recording medium 300 stuck to the surface of fabric transport member 210, transport device 200 transports recording medium 300 directly below recording unit 120, and recording unit 120 records on recording medium 300. Then, recording medium transport member 210 and recording medium 300 are separated by recording medium transport roller 112.

[0062] The recording unit 120 may eject an ink composition or the like by an inkjet method. In this embodiment, it is assumed that an inkjet head is used for the recording unit 120 and that printing is performed on a textile fabric as the recording medium 300, but the present invention is not limited to this.

[0063] The conveying device 200 may include a pair of conveying rollers 221 and 222 , a fabric conveying member 210 , a drive motor 230 , a control device 240 , a cleaning unit 250 , and a removing member 260 .

[0064] The transport rollers 221 and 222 are rollers for transporting the fabric transport member 210 in a fixed direction. The fabric transport member 210 may be a belt member having an adhesive layer on its surface, and is provided around the transport rollers 221 and 222. The fabric transport member 210 transports the recording medium in the direction of arrow c as the transport rollers 221 and 222 are rotated by a drive motor 230. The control device 240 may control either or both of the transport device 200 and the inkjet printing apparatus 100.

[0065] The cleaning unit 250 cleans the surface of the fabric transport member 210 that has been separated from the recording medium 300. The cleaning unit 250 cleans the components of the recording medium 300 and the printing colorant that have adhered to the fabric transport member 210 during printing. The cleaning unit 250 may include a pump (not shown), a water sprinkler port, and a water sprinkler pipe.

[0066] The removal member 260 removes water that has adhered to the fabric transport member 210 by the cleaning unit 250. The removal member 260 is not particularly limited, but may be, for example, a blade. The material of the blade is preferably an elastic material. Furthermore, polyurethane is preferable from the viewpoint of abrasion resistance. The contact portion with the fabric transport member 210 may have a rectangular cross section, or may have a shape with an obliquely cut-off tip.

[0067] An elastic material is preferable for the fabric transport member 210. A heater (not shown) may be installed to warm the fabric transport member 210. In the process of washing the fabric transport member 210, a water receiving section (not shown) for receiving washing water, a brush (not shown) for cleaning the fabric transport member 210, a sponge (not shown), etc. may be used.

[0068] Examples of the recording medium 300 include fabrics made of natural or synthetic fibers such as silk, cotton, wool, nylon, polyester, rayon, etc. The fabrics may also be woven fabrics, knitted fabrics, nonwoven fabrics, etc.

[0069] 4. Fabric transport member for inkjet printing device The fabric transport member of the inkjet printing apparatus of this embodiment has an adhesive layer derived from the aqueous pressure-sensitive adhesive composition on its surface. The fabric transport member is not particularly limited, but is preferably made of, for example, an elastic material, and particularly preferably contains a urethane resin. By using the aqueous pressure-sensitive adhesive composition described above for such a fabric transport member, the adhesion between the adhesive layer and the fabric transport member is further improved, and water resistance is improved.

[0070] 5. Inkjet printing method The inkjet textile printing method includes a transporting step of adhering a fabric to an adhesive layer made of the aqueous adhesive composition formed on the surface of a fabric transport member of an inkjet textile printing device and transporting the fabric; a recording step of performing textile printing recording on the fabric adhering to the adhesive layer using an inkjet head; and a cleaning step of cleaning the adhesive layer from which the fabric has been peeled off after textile printing recording.

[0071] 5.1.Transportation process The conveying step is a step of laminating a fabric to the adhesive layer of the aqueous adhesive composition formed on the surface of a fabric conveying member of an inkjet printing apparatus, and conveying the fabric. The laminating method is not particularly limited, but examples thereof include a method in which the two are pressed together using a conveying roll, as shown in Figure 1.

[0072] 5.2. Recording process The recording process is a process of performing textile printing recording on the fabric attached to the adhesive layer using an inkjet head. In the recording process, the fabric is transported in a state where the fabric transport member and the fabric are in close contact with each other via the adhesive layer on the surface of the fabric transport member, and during the transport process, ink is ejected from the recording unit 120 and adhered to the fabric. Thereafter, the fabric with the ink adhered thereto may be peeled off from the adhesive layer and collected.

[0073] 5.3.Cleaning process The cleaning step is a step of cleaning the adhesive layer from which the fabric has been peeled off after textile printing. This step makes it possible to remove lint and other debris from the adhesive layer surface that has adhered during the printing step. [Example]

[0074] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0075] 1. Preparation of aqueous adhesive composition A reactor equipped with a stirrer, reflux condenser, thermometer, nitrogen inlet tube, and dropping funnel was charged with 114 g of ion-exchanged water and heated to 82°C. Subsequently, a total of 498 g of monomers weighed to have the composition ratio shown in Table 1 below, 79 g of ion-exchanged water, 34 g of Emulgen 123P (surfactant, trade name, manufactured by Kao Corporation), and 34 g of Hitenol LA12 (surfactant, trade name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) were added and mixed with stirring. 249 g of a 2% by mass aqueous solution of ammonium persulfate (polymerization initiator) was added to the homogenized solution at 82°C over 1.5 hours.

[0076] After adding all the ingredients listed above, the mixture was kept warm for 1 hour, cooled, and then ion-exchanged water was added and aqueous ammonia was added as a pH adjuster. The mixture was then filtered through a 150-mesh nylon filter to remove coarse particles, yielding an aqueous pressure-sensitive adhesive composition containing a (meth)acrylic resin having the composition listed in Table 1.

[0077] The monomers for the structural units of the (meth)acrylic resins shown in Table 1 are as follows. The value in parentheses indicates the glass transition temperature of the homopolymer. In Table 1, the total weight parts of all structural units are listed so that it equals 100 weight parts. The glass transition temperature Tg of the (meth)acrylic resins was measured by differential scanning calorimetry (DSC) in accordance with JIS K7121. 2EHA: 2-ethylhexyl acrylate (-70°C) BA: Butyl acrylate (-55°C) BMA: Butyl methacrylate (20°C) EMA: Ethyl methacrylate (65°C) MMA: Methyl methacrylate (105°C) AA: Acrylic acid (106°C) MAA: methacrylic acid (130°C)

[0078] 2. Evaluation Method 2.1.Adhesion of adhesive layer A conveyor belt with a urethane surface was attached to an Epson ML-8000 digital textile printing machine. The aqueous pressure-sensitive adhesive composition prepared as described above was applied to the conveyor belt and dried to form a pressure-sensitive adhesive layer. The test environment was then adjusted to temperatures of 5°C, 20°C, and 35°C, and a fabric was attached to the conveyor belt, conveyed, and peeled off in this order, as shown in Figure 1.

[0079] The adhesive properties were evaluated using two types of fabric: a thin, see-through British organza fabric, which is difficult to stick to and weak to pulling, and a 100% cotton fabric, which is easy to stick to.

[0080] The adhesiveness was evaluated based on the following evaluation criteria after the fabric was conveyed for 10 m and after being conveyed for 10,000 m. The 10,000 m conveyance was used to evaluate durability. (Evaluation criteria) A: It can be transported without peeling off. B: Partial peeling may be observed during transport, but transport is possible. C: Peeling occurs to such an extent that transportation must be stopped during transportation, making it impractical.

[0081] 2.2. Mechanical strength of adhesive layer Using the above-mentioned ML-8000 digital textile printing machine, water brush cleaning was carried out as shown in Figure 1. The fabric was transported for 10 m and 10,000 m, and the mechanical strength was evaluated based on the following evaluation criteria. (Evaluation criteria) A: The adhesive layer did not peel off from the fabric conveying member (conveyor belt). C: The adhesive layer peeled off from the fabric conveying member (conveyor belt).

[0082] 2.2.Water resistance of adhesive layer Using the ML-8000 digital textile printing machine, water brush cleaning was performed as shown in Figure 1. The fabric was transported for 10 m and 10,000 m, and the water resistance was evaluated based on the following evaluation criteria. Visually evaluated areas where the adhesive layer had turned white also indicated a decrease in adhesive strength. (Evaluation criteria) A: The adhesive layer was transparent. B: The adhesive layer was partially whitened. C: The adhesive layer was entirely white.

[0083] 3. Evaluation Results The compositions and evaluation results of the aqueous pressure-sensitive adhesive compositions used in each example are shown in Table 1. Table 1 shows that when the aqueous pressure-sensitive adhesive composition for forming an adhesive layer on the surface of a fabric transport member of an inkjet printing device contains a predetermined (meth)acrylic resin and a pH adjuster, the adhesive layer formed on the fabric transport member has improved durability of adhesive force, water resistance, and mechanical strength, and the adhesiveness is maintained over a wide temperature range.

[0084] In addition, a test was conducted in the same manner as in Example 1 using a conveyor belt having a polyester resin surface instead of a urethane resin. As a result, it was confirmed that a urethane resin conveyor belt has higher adhesive durability, water resistance, and mechanical strength, and also has a wider temperature range in which adhesive strength is properly exerted. Therefore, the aqueous pressure-sensitive adhesive composition of this embodiment can be suitably used when a fabric conveying member containing a urethane resin is used. [Explanation of symbols]

[0085] 100...inkjet printing device, 111, 112...recording medium transport rollers, 120...recording unit, 200...transport device, 210...fabric transport member, 221, 222...transport rollers, 230...drive motor, 240...control device, 250...cleaning unit, 260...removal member, 300...recording medium.

Claims

1. An aqueous adhesive composition for forming an adhesive layer on a surface of a fabric transport member of an inkjet textile printing device, comprising: A (meth)acrylic resin, a pH adjuster, and water, The (meth)acrylic resin contains, as structural units, four or more types of (meth)acrylate units A and one or more types of (meth)acrylic acid units B, the (meth)acrylic resin has a glass transition temperature of −25 to −8° C., the difference between the maximum and minimum glass transition temperatures of the homopolymers constituted by the respective structural units is 170°C or more; Aqueous pressure-sensitive adhesive compositions.

2. The content of the (meth)acrylic acid unit B is 0.1 to 3.0 mass% based on the total amount of the (meth)acrylic resin. The aqueous pressure-sensitive adhesive composition according to claim 1 .

3. the four or more types of (meth)acrylate units A include two or more types of units A1 derived from a (meth)acrylate having a homopolymer glass transition temperature of 15°C or higher, and two or more types of units A2 derived from a (meth)acrylate having a homopolymer glass transition temperature of -50°C or lower; The aqueous pressure-sensitive adhesive composition according to claim 1 .

4. the four or more types of (meth)acrylate units A include structural units derived from one or more monomers selected from the group consisting of 2-ethylhexyl acrylate, butyl acrylate, butyl methacrylate, ethyl methacrylate, and methyl methacrylate; The aqueous pressure-sensitive adhesive composition according to claim 1 .

5. the four or more types of (meth)acrylate units A include a structural unit derived from butyl acrylate and a structural unit derived from butyl methacrylate; The structural unit derived from butyl acrylate and the structural unit derived from butyl methacrylate are the structural units having the highest content and the structural units having the second highest content, respectively. The aqueous pressure-sensitive adhesive composition according to claim 1 .

6. The pH adjuster comprises ammonia or an ammonium salt. The aqueous pressure-sensitive adhesive composition according to claim 1 .

7. The fabric conveying member contains a urethane resin. The aqueous pressure-sensitive adhesive composition according to claim 1 .

8. The method comprises a step of applying the aqueous pressure-sensitive adhesive composition according to any one of claims 1 to 7 to a surface of a fabric transport member of an inkjet textile printing apparatus to form a pressure-sensitive adhesive layer. Method of providing adhesiveness.

9. a conveying mechanism for conveying a fabric by laminating the fabric to the pressure-sensitive adhesive layer made of the aqueous pressure-sensitive adhesive composition according to any one of claims 1 to 7, the pressure-sensitive adhesive layer being formed on the surface of a fabric-conveying member; a recording unit that performs textile printing on the fabric attached to the adhesive layer using an inkjet head; a cleaning unit that cleans the adhesive layer from which the fabric has been peeled off after the textile printing recording, Inkjet printing equipment.

10. A pressure-sensitive adhesive layer made from the aqueous pressure-sensitive adhesive composition according to any one of claims 1 to 7 is provided on the surface thereof. A fabric transport member for an inkjet printing device.

11. a conveying step of laminating a fabric to an adhesive layer of the aqueous pressure-sensitive adhesive composition according to any one of claims 1 to 7, the adhesive layer being formed on a surface of a fabric-conveying member of an inkjet printing apparatus, and conveying the fabric; a recording step of performing textile printing on the fabric attached to the adhesive layer using an inkjet head; and a cleaning step of cleaning the adhesive layer from which the fabric has been peeled off after the textile printing. Inkjet printing method.

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