JP7056272B2 - Inkjet recording liquid set and inkjet recording method - Google Patents

Description

The present invention relates to an inkjet recording liquid set and an inkjet recording method. More specifically, when a low-absorbent base material or a non-absorbent base material is used as a recording medium, an inkjet recording liquid set and an inkjet that can enable recording with a large dot diameter and less unevenness and bleeding. Regarding the recording method.

In the printing field, inkjet printing methods have been developed and are widely put into practical use. When printing with inkjet ink (hereinafter, also simply referred to as “ink”) and an inkjet printer, the ink droplets ejected from the print head land on the recording medium and then permeate and fix to form dots, and these dots form dots. An image is formed by gathering a large number of them. The process of forming these dots is important for forming a clear image.

As the recording medium, various materials such as uncoated paper, coated paper, stretched polypropylene resin, polyester resin and vinyl chloride resin are used.

Of these, if a low-absorbent base material such as coated paper or resin or a non-absorbent base material is used as the recording medium, the water-based ink does not easily penetrate into the recording medium, so a recording medium such as non-coated paper can be used. The bleeding that occurs is unlikely to occur.

However, the water-based ink landed on these recording media by the inkjet method has a problem that the dots do not spread sufficiently and the dot diameter is small. When the dot diameter is small, the coloring material cannot be uniformly applied to the surface of the recording medium, which may cause unevenness or excessive gaps between the dots to cause white spots. Further, since the droplets of the water-based ink remain on the surface of the recording medium, there is a problem that the coloring material is difficult to fix, uneven color mixing occurs in the boundary region of different colors, and bleeding is likely to occur. rice field.

To solve such a problem, for example, in Patent Document 1, a pretreatment layer (also referred to as an ink receiving layer) formed by drying a pretreatment liquid is provided on the surface of these base materials before printing, thereby landing. The dot diameter of the water-based ink is controlled to suppress white spots in the image.

However, the pretreatment liquid is difficult to get wet on a low absorption base material or a non-absorbent base material. Therefore, the applicability has been improved by using or using a water-soluble organic solvent as the pretreatment liquid. However, the use of a water-soluble organic solvent has concerns from the viewpoint of safety and volatility.

In addition, there are base materials having significantly different polarities among the low-absorbent base material or the non-absorbent base material. For example, polyethylene terephthalate (PET) is relatively polar and hydrophilic, while stretched polypropylene (OPP) is hydrophobic. It has been required to obtain a good image in which dots are sufficiently spread even on such substrates having different polarities.

Patent Document 2 describes that high-quality images can be obtained for various base materials by including a specific metal salt in the pretreatment liquid, but the types of the base material are also limited. It was a target.

Japanese Unexamined Patent Publication No. 2012-201814 Japanese Unexamined Patent Publication No. 2013-188958

The present invention has been made in view of the above problems and situations, and the problem to be solved is that when a low-absorbent base material or a non-absorbent base material is used as a recording medium, the dot diameter formed is large and uneven. It is an object of the present invention to provide an inkjet recording liquid set and an inkjet recording method capable of recording with less bleeding.

In order to solve the above problems, the present inventor has added a short siloxane chain silicone-based surfactant having a structure represented by the following general formula (1) to the pretreatment liquid in the process of examining the cause of the problem. We have found that the dot diameter can be expanded and the image quality can be improved even in a non-absorbent recording medium such as PET or OPP by containing the above-mentioned material, and the present invention has been made.

That is, the above-mentioned problem according to the present invention is solved by the following means.

1. 1. An inkjet recording liquid set containing at least an inkjet ink and a pretreatment liquid, which uses a low-absorbing base material or a non-absorbent base material as a recording medium.
The inkjet ink contains at least a pigment, a pigment dispersant, a water-soluble organic solvent, and water.
The pretreatment liquid contains at least composite resin fine particles obtained by emulsifying a polyolefin resin into a polyurethane resin, a flocculant, and a silicone-based surfactant, and
The silicone-based surfactant contained in the pretreatment liquid has a structure represented by the following general formula (1), and the addition amount is 0.5 to 3.0% by mass with respect to the pretreatment liquid. An inkjet recording liquid set characterized by being in the range of .

(In the formula, R represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms. X is an alkylene group having 2 to 6 carbon atoms and may have a branched structure. EO is poly. Represents the repeating unit structure of ethylene oxide. PO represents the repeating unit structure of polypropylene oxide. The order of [EO] _m and [PO] _n may be either. N and m represent the number of repeating unit structures. , M is an integer of 2 to 50, and n is an integer of 0 to 20.)

2. 2. The inkjet recording liquid set according to item 1, wherein the flocculant is a polyvalent metal salt or an organic acid.

3 . An inkjet recording method comprising the use of the inkjet recording liquid set according to the first or second paragraph .

By the above means of the present invention, when a low-absorbent base material or a non-absorbent base material is used as a recording medium, an inkjet recording liquid capable of recording with a large dot diameter and less unevenness and bleeding is possible. A set and inkjet recording method can be provided.

Although the mechanism of expression or mechanism of action of the effect of the present invention has not been clarified, it is inferred as follows.

The silicone-based surfactant contained in the pretreatment liquid and having the structure represented by the general formula (1) has a short hydrophobic siloxane chain and is compact, so that it can easily orient to the liquid surface quickly and exert a dynamic surface tension. It has the effect of greatly lowering it. Therefore, the applicability of the pretreatment liquid can be remarkably improved, and the pretreatment liquid can be uniformly applied on the substrate.

Further, since the surfactant having a short siloxane chain tends to be oriented on the liquid surface as described above, it exists on the surface of the pretreatment layer formed by drying after applying the pretreatment liquid. When the water-based ink lands on the surface of the pretreatment layer, this silicone-based surfactant has a very high compatibility with the water-based ink due to the short siloxane chain, and is considered to be compatible with the ink. As a result, even when the water dries after landing and the constituent solvent in the ink is mainly an organic solvent, the presence of the silicone-based surfactant makes it possible to maintain a low surface tension of the ink. We believe that this has led to an increase in the dot diameter.

The inkjet recording liquid set of the present invention is an inkjet recording liquid set containing at least an inkjet ink and a pretreatment liquid used for a low-absorptive base material or a non-absorbent base material, and the inkjet ink is at least a pigment. It contains a pigment dispersant, a water-soluble organic solvent, and water, and the pretreatment liquid contains at least water-insoluble resin fine particles, a flocculant, and a silicone-based surfactant, and is contained in the pretreatment liquid. The silicone-based surfactant is characterized by having a structure represented by the general formula (1). This feature is a technical feature common to or corresponding to each of the following embodiments.

As an embodiment of the present invention, it is preferable that the flocculant is a polyvalent metal salt or an organic acid. The reason is considered to be that, for example, a coagulant such as a cationic polymer has a weak coagulating force and spreads too much when wet, so that adjacent dots greatly overlap each other, leading to deterioration of image quality. When a coagulant with a strong coagulating force such as an acid or a polyvalent metal salt is used, and if there is a surfactant in the ink that has the effect of lowering the surface tension, the balance between coagulation and wettability is good. It is considered that the image quality will be improved.

Further, it is preferable that the water-insoluble resin fine particles contain a polyurethane resin. By using a polyurethane resin, the effect of improving the balance between aggregation and wettability is exhibited more effectively. The polyurethane resin consists of a soft segment and a hard segment. In a polyurethane resin having a soft segment such as a soft segment, the soft segment portion is appropriately swollen by the organic solvent in the ink to promote the diffusion of the flocculant. , It is considered that a more uniform coating state is maintained by the hard segment part. On the other hand, a compact surfactant having a short siloxane chain, such as the silicone-based surfactant according to the present invention, is easy to move, diffuses more effectively into the ink, maintains wettability, and is an ink as a flocculant. We believe that better images can be formed by promoting diffusion into the ink.

Further, in the present invention, it is preferable that the water-insoluble resin fine particles are composite resin fine particles obtained by emulsifying a polyolefin resin into a polyurethane resin. This is because, in addition to the above reasons, the composite of the olefin moiety improves the coatability and the uniform film forming property, and the flexible olefin moiety is composited, so that the silicone according to the present invention is more. It is considered that the image quality will be further improved because the system surfactant and the flocculant are effectively diffused into the ink appropriately.

As an embodiment of the present invention, from the viewpoint of exhibiting the effect of the present invention, the content of the silicone-based surfactant is in the range of 0.1 to 3.0% by mass with respect to the pretreatment liquid. Is preferable.

Further, in the inkjet recording method of the present invention, it is preferable to use the inkjet recording liquid set according to any one of the items 1 to 5.

Hereinafter, the present invention, its constituent elements, and modes and embodiments for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical values described before and after it as the lower limit value and the upper limit value.

Further, the recording liquid set in the present invention is at least a pretreatment liquid which is a non-colored liquid whose purpose is to assist the formation of an image and an inkjet which is a colored liquid whose purpose is to form an image. Refers to a combination that contains ink. The number of each component may be one or more, and they are collectively called a recording liquid set.

<< Overview of Inkjet Recording Liquid Set >>
The inkjet recording liquid set of the present invention is an inkjet recording liquid set containing at least an inkjet ink and a pretreatment liquid used for a low-absorbing base material or a non-absorbent base material, and the inkjet ink is at least a pigment. It contains a pigment dispersant, a water-soluble organic solvent, and water, and the pretreatment liquid contains at least composite resin fine particles obtained by emulsifying a polyolefin resin into a polyurethane resin, a flocculant, and a silicone-based surfactant. Moreover, the silicone-based surfactant contained in the pretreatment liquid has a structure represented by the following general formula (1), and the addition amount is 0.5 to 3. It is characterized in that it is in the range of 0% by mass .

The pretreatment liquid according to the present invention can have a function of accelerating image formation of ink and improving image quality when an image is recorded on a substrate by an inkjet printing method. Specifically, for example, by applying and drying the pretreatment liquid in advance on the substrate of the surface to be inkjet printed, the dot diameter of the landed droplet can be determined even if the substrate is low-absorbent or non-absorbent. Can be made larger.

In the present invention, since the pretreatment liquid has a compound having a structure represented by the general formula (1), the applicability of the pretreatment liquid is remarkably improved, and the base material is low-absorbent or non-absorbable. The formed dot diameter can also be increased.

[Pretreatment liquid]
In the present invention, the pretreatment liquid contains at least composite resin fine particles obtained by emulsifying a polyolefin resin into a polyurethane resin, a flocculant, and a silicone-based surfactant, and is contained in the pretreatment liquid. The silicone-based surfactant is characterized by having a structure represented by the following general formula (1).

(Silicone-based surfactant)

(In the formula, R represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms. X is an alkylene group having 2 to 6 carbon atoms and may have a branched structure. EO is poly. Represents the repeating unit structure of ethylene oxide. PO represents the repeating unit structure of polypropylene oxide. The order of [EO] _m and [PO] _n may be either. N and m represent the number of repeating unit structures. , M is an integer of 2 to 50, and n is an integer of 0 to 20.)
In the present application, "EO" represents a repeating unit structure of polyethylene oxide, that is, a structure in which ethylene oxide, which is a cyclic ether of a three-membered ring, is ring-opened. Further, "PO" represents a repeating unit structure of polypropylene oxide, that is, a structure in which propylene oxide, which is a three-membered ring cyclic ether, is ring-opened.

Here, "the order of [EO] _m and [PO] _n does not matter" means that in the compound molecule represented by the general formula (1), the order of the binding positions with respect to the siloxane skeleton as the parent is appropriately changed. Say good things.

In the general formula (1), R is preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group or a butyl group, more preferably a hydrogen atom or a methyl group, and further preferably a hydrogen atom. preferable.
X represents an alkylene group having 2 to 6 carbon atoms, and is preferably an alkylene group having 3 carbon atoms (that is, a propylene group).

m represents an integer of 2 to 50. It is more preferable that m is an integer of 5 to 20. n represents an integer from 0 to 20. It is more preferable that n is an integer of 0 to 6.

Specific examples of the silicone-based surfactant having the structure represented by the general formula (1) are shown below, but the present invention is not limited thereto.

(S1): In the general formula (1), R = methyl group, X = alkylene group having 3 carbon atoms, m = 9, n = 0.
(S2): In the general formula (1), R = hydrogen atom, X = alkylene group having 3 carbon atoms, m = 3, n = 0.
(S3): In the general formula (1), R = hydrogen atom, X = alkylene group having 3 carbon atoms, m = 12, n = 3.
From the viewpoint of exhibiting the effect of the present invention, the silicone-based surfactant having the structure represented by the general formula (1) is in the range of 0.1 to 3.0% by mass with respect to the pretreatment liquid. preferable. It is more preferably in the range of 0.5 to 2.0% by mass.

(Water-insoluble resin fine particles)
The pretreatment liquid contains water-insoluble resin fine particles. The water-insoluble resin fine particles used in the present invention are water-insoluble resin fine particle dispersions that can accept ink for inkjet (inkjet ink) and exhibit solubility or affinity for ink.

The water-insoluble resin fine particles are originally water-insoluble, but have a form in which the resin is dispersed in an aqueous medium as microfine particles, and are water-insoluble, which are forcibly emulsified with an emulsifier or the like and dispersed in water. There are resins or water-insoluble resins that can self-emulsify by introducing hydrophilic functional groups into the molecule to form a stable aqueous dispersion on their own without the use of emulsifiers or dispersion stabilizers. These resins are usually used in a state of being emulsified and dispersed in water or a water / alcohol mixed solvent.

<Polyurethane resin>
In the present invention, the water-insoluble resin fine particles preferably contain a polyurethane-based resin. The polyurethane resin contains at least one of a polyurethane resin having a carbonate moiety, a polyurethane resin having an ester moiety, a polyurethane resin having an ether moiety, a urethane / acrylic composite resin, and a urethane / olefin composite resin. Is preferable. Among these, urethane / olefin composite resin is preferable from the viewpoint of water resistance and substrate followability.

Examples of the polyurethane resin having a carbonate moiety, the polyurethane resin having an ester moiety, the polyurethane resin having an ether moiety, the urethane / acrylic composite resin and the urethane / olefin composite resin and their synthetic methods are disclosed in JP-A-2017-171904. And Japanese Patent Application Laid-Open No. 2-238015.

Further, these polyurethane resins can be obtained from commercially available products. For example, UCOAT UWS-145, UX-390 (above, manufactured by Sanyo Chemical Industries, Ltd.), Superflex 150, 210, 820 (above, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), WEM505, WEM-3008, WBR2101 (above, Examples include Taisei Fine Chemicals Co., Ltd.), ST053-D (Ube Kosan Co., Ltd.), R-9699 (Kusumoto Kasei Co., Ltd.) and Juliano W600 (Arakawa Chemical Industries Co., Ltd.).

<Composite resin fine particles obtained by emulsifying a polyolefin resin into a polyurethane resin>
The water-insoluble resin fine particles according to the present invention preferably contain a urethane / olefin composite resin. Further, it is preferable that the polyolefin-based resin is a composite resin obtained by emulsifying the polyurethane-based resin into a polyurethane-based resin.

That is, in the water-insoluble resin fine particles containing the composite resin, the polyurethane-based resin is different from the resin that exists at the interface between the polyolefin-based resin as the water-insoluble resin and water, which is a continuous phase, and protects the water-insoluble resin. It functions as a water-insoluble resin layer. By forming the composite resin fine particles obtained by emulsifying the polyolefin resin with the polyurethane resin in this way, it is possible to suppress a decrease in compatibility with the polyurethane resin and the flocculant in the case of the polyolefin resin alone. Compared with the case where the polyolefin-based resin and the polyurethane-based resin are each emulsified and simply mixed, the physical properties of the coating film can be improved, and the stability of the pretreatment liquid according to the present invention can be improved.

The composite resin fine particles may be obtained by the production method (I) described later, or may be obtained by the production method (II).

The value (U / O) of the mass ratio of the polyurethane-based resin (U) and the polyolefin-based resin (O) in the composite resin fine particles is preferably 40/60 to 95/5. When the abundance ratio of the polyurethane resin is within the above range, the compatibility with the dispersant tends to be improved, and the solvent resistance is also excellent. Further, when the abundance ratio of the polyolefin-based resin is within the above range, the adhesion to the polyolefin-based film substrate is excellent. A more preferable range of the abundance ratio is (U / O) = 40/60 to 80/20.

The total resin concentration of the polyolefin-based resin and the polyurethane-based resin in the composite resin fine particles is not particularly limited, but is usually in the range of 5% by mass or more, preferably 10 to 70% by mass.

At the time of emulsification, a surfactant can be used as an emulsifier together with the polyurethane resin. That is, the composite resin fine particles according to the present invention may further contain a surfactant as an emulsifier. By adding a surfactant, the storage stability of the composite resin fine particles can be further improved.

As such a surfactant, it is preferable to use either one or both of an anionic surfactant and a nonionic surfactant. It is preferable to blend 1 to 20 parts by mass of these anionic surfactants and nonionic surfactants in total with respect to 100 parts by mass of the total resin. When the blending amount is 20 parts by mass or less, the water resistance and the solvent resistance tend to be excellent.

Further, the value of the compounding mass ratio (X / Y) of the anionic surfactant (X) and the nonionic surfactant (Y) is preferably 100/0 to 50/50. By setting the blending amount of the anionic surfactant in the above range, the emulsifying property and the storage stability can be further improved.

Here, examples of the anionic surfactant include alkyl sulfates, polyoxyethylene alkyl ether sulfates, sulfosuccinates, alphaolefin sulfonates, N-acylamino acid salts, carboxylates, phosphate esters and the like. Be done. Among these, sulfosuccinate and alphaolefin sulfonate are preferable. The type of salt is not particularly limited, but metal salts such as sodium salt, potassium salt and magnesium salt, triethanolamine salt and the like are preferable.

Examples of the nonionic surfactant include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl amine ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters and the like. Be done. Among these, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers and the like are preferable.

Antioxidants, lightfasteners, plasticizers, foaming agents, thickeners, colorants, flame retardants, other aqueous resins, and various fillers are added to the composite resin fine particles according to the present invention as long as the performance is not impaired. be able to. Examples of the antioxidant include solutions or emulsions of antioxidants such as hindered phenols or semicarbazides. Examples of the light-resistant agent include solutions or emulsions of light-resistant agents such as hindered amine (HALS) -based, benzophenone-based, and benzotriazole-based.

Further, various cross-linking agents such as epoxy-based, carbodiimide-based, oxazolidine-based, blocked isocyanate-based, and isocyanate-based cross-linking agents can be added to the composite resin fine particles according to the present invention in order to impart higher durability.

A method for producing composite resin fine particles according to the present invention will be described.

The above-mentioned composite resin fine particles can be prepared by the following production method (I) or (II).

(I) A method in which a polyolefin resin is emulsified in water with a urethane prepolymer having a hydrophilic group, and then an amine compound as a chain extender or an aqueous solution thereof is added to extend the chain of the urethane prepolymer. ..

(II) An aqueous dispersion of a polyurethane resin is prepared by emulsifying a urethane prepolymer having a hydrophilic group into water and further adding an amine compound as a chain extender or an aqueous solution thereof to extend the chain of the urethane prepolymer. Next, a method of emulsifying a polyolefin-based resin with an aqueous dispersion of the polyurethane-based resin.

An embodiment related to the manufacturing method (I) described above will be described. In this method, first, a resin solution obtained by dissolving a polyolefin resin in a solvent and a solution of a urethane prepolymer having a hydrophilic group are mixed, and water is added to the mixture and stirred to emulsify.

Examples of the solvent include organic solvents such as hexane, isohexane, pentane, cyclohexane, methylcyclohexane, heptane, isooctane, methylethylketone, xylene, toluene and benzene, and solvents other than water such as carbon dioxide in a supercritical state. , These can be used alone or in combination of two or more.

The emulsification method may be any of known forced emulsification methods, phase inversion emulsification methods, D-phase emulsification methods, gel emulsification methods, etc. , And combined stirring, sand mills, and multi-screw extruders can be used. Further, at the time of emulsification, the above-mentioned surfactant may be mixed together with the urethane prepolymer.

Next, after diluting the emulsion with water, an amine compound as a chain extender is added to crosslink the residual isocyanate group of the urethane prepolymer with the chain extender to increase the molecular weight of the polyurethane resin. Then, by distilling off the organic solvent, a composite resin fine particle dispersion (that is, a dispersion in which water-insoluble resin fine particles are dispersed) containing a polyolefin resin inside the polyurethane resin can be obtained.

In the composite resin fine particle dispersion thus obtained, when the polyolefin-based resin is a modified polyolefin, the acid component introduced into the polymer may be neutralized by adding a basic substance. By ionizing the same portion by neutralization, the polymer molecule is elongated and the viscosity of the entire system is increased, so that the composite resin fine particle dispersion can be more stable. Further, in this case, the pH can be adjusted to a desired value depending on the amount of the basic substance added.

The basic substance used is not particularly limited as long as it can neutralize the acid moiety in the polyolefin resin, and for example, methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, ethanolamine, etc. Propanolamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dihexylamine, dioctylamine, diethanolamine, dipropanolamine, N-methyldiethanolamine, triethylamine, N, N-dimethylethanolamine, 2-dimethylamino-2-methyl Organic basic substances such as -1-propanol, 2-amine-2-methyl-1-propanol, and morpholin, aqueous ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium hydrogencarbonate, ammonium carbonate, potassium carbonate, etc. Inorganic basic substances can be mentioned. When these basic substances are used, one kind may be used, but when two or more kinds of basic substances are used in combination, the object of the present invention is often achieved more effectively. When an amine compound is used as the basic substance, a tertiary amine is used to add the urethane prepolymer before the chain is extended so as not to react with the free isocyanate. On the other hand, when neutralizing the modified polyolefin after chain extension, any of primary, secondary or tertiary amines can be used.

The amount of the basic substance used for neutralization varies depending on the degree of modification of the modified polyolefin, but is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the modified polyolefin. When the amount of the basic substance is 0.1 parts by mass or more, the pH becomes neutral, and therefore the storage stability of the composite resin fine particle dispersion is improved. On the other hand, when the amount of the basic substance is 10 parts by mass or less, the storage stability of the composite resin fine particle dispersion is good, the basicity is not strong, and a large amount of hydrophilic substance is not introduced into the coating film. Water resistance is improved.

An embodiment related to the above-mentioned manufacturing method (II) will be described. In this method, first, water is added to a solution of a urethane prepolymer having a hydrophilic group to emulsify it, and then an amine compound as a chain extender is added to the obtained emulsified solution to leave the urethane prepolymer. The isocyanate group is crosslinked with the chain extender to prepare an aqueous dispersion of a high molecular weight polyurethane resin.

Then, the resin solution obtained by dissolving the polyolefin resin in a solvent and the aqueous dispersion of the polyurethane resin having the hydrophilic group obtained above are mixed, and the polyolefin is obtained from the polyurethane resin having the hydrophilic group. By emulsifying the based resin, diluting it with water, and then distilling off the organic solvent, the composite resin fine particle dispersion containing the polyolefin resin (that is, the water-insoluble resin fine particles are dispersed inside the polyurethane resin. Dispersion) is obtained.

The solvent and emulsification method in the method (II) are the same as those in the method (I). Further, also in the method (II), a surfactant may be mixed with the polyurethane resin when emulsifying the polyolefin resin. Further, in the obtained composite resin fine particle dispersion, the modified polyolefin may be neutralized with a basic substance, which is the same as the above method (I).

The average particle size of the composite resin fine particles is not particularly limited, but is preferably in the range of 10 to 500 nm, more preferably in the range of 10 to 300 nm, and further preferably in the range of 10 to 200 nm. The average particle size can be measured by a commercially available particle size measuring device using a dynamic light scattering method, an electrophoresis method, etc., but the measurement by the dynamic light scattering method is simple and the particle size region can be measured. It can be measured accurately.

These resins may be copolymers using other monomers.

The weight average molecular weight of the water-insoluble resin fine particles is preferably in the range of 10,000 to 1,000,000.

(Coagulant)
The pretreatment liquid according to the present invention contains a material that causes agglomerates when it comes into contact with an inkjet ink containing a pigment, that is, a coagulant, so that the interaction with the inkjet ink is increased and water solubility is increased. Ink dots can be more fixed.

The flocculant preferably contains any one of a cationic resin, a metal chelating agent, a polyvalent metal salt and an organic acid, and more preferably any one of a polyvalent metal salt and an organic acid.

The cationic resin and the polyvalent metal salt can aggregate anionic components (usually a coloring material, a pigment, etc.) in the inkjet ink by salting out. The organic acid can aggregate anionic components in the inkjet ink by changing the pH.

Examples of the cationic resin include polyallylamine, polyvinylamine, polyethyleneimine, polydiallyldimethylammonium chloride and the like.

Examples of the above metal chelating agents include acetylacetone and acetoaceto, which have nitrogen-containing groups in metals such as aluminum, zinc, cadmium, nickel, cobalt, copper, calcium, barium, titanium, manganese, iron, lead, zirconium, chromium and tin. Includes metal chelate compounds coordinated with methyl acetate, ethyl acetoacetate, ethyl lactate, methyl salicylate and the like.

Examples of the polyvalent metal salt include water-soluble salts such as calcium salt, magnesium salt, aluminum salt and zinc salt.

The organic acid contained in the pretreatment liquid can aggregate pigments that can be contained in the inkjet ink, and the first dissociation constant is preferably 3.5 or less, preferably in the range of 1.5 to 3.5. Is preferable. Within this range, liquid leakage is further prevented in the low density area where the printing rate is low, and beading in the high density area where the printing rate is high is further improved.

It is preferable to use an organic acid that has not been completely neutralized by a base. Neutralization with a base means that the acidic groups of these acids are ionic bonded to other positively charged elements or compounds (eg, inorganic compounds such as metals). Further, the fact that the organic acid is not completely neutralized means that among the acidic groups of the organic acid, the acidic groups that do not form the ionic bond are present. By using an organic acid having an acidic group that does not form an ionic bond, it is possible to form a transparent pretreatment layer with high compatibility with the composite resin particles having a polyurethane structure contained in the pretreatment liquid. It is considered that the color tone of the formed image becomes more vivid than when a polyvalent metal salt or the like is used. Further, by using an organic acid, it is easy to maintain the storage stability of the pretreatment liquid, and blocking does not easily occur after the pretreatment liquid is applied and dried. From the above viewpoint, preferred organic acids are formic acid, acetic acid, propionic acid, isobutyric acid, oxalic acid, fumaric acid, malic acid, citric acid, malonic acid, succinic acid, maleic acid, benzoic acid and 2-pyrrolidone-5-carboxylic acid. , Lactic acid, acrylic acid and its derivatives, methacrylic acid and its derivatives, or compounds having a carboxy group including acrylamide and its derivatives, sulfonic acid derivatives, or phosphoric acid and its derivatives.

The content of the organic acid in the pretreatment liquid may be an amount that adjusts the pH of the pretreatment liquid to be less than the first dissociation constant of the organic acid. By incorporating an organic acid in an amount such that the pH of the treatment liquid is less than the first dissociation constant of the organic acid in the pretreatment liquid, bleeding during high-speed printing can be effectively suppressed.

The composite resin particles having a polyurethane structure contained in the pretreatment liquid according to the present invention make it possible to suppress bleeding of an inkjet recorded image and to achieve both adhesion. The reason for this is not clear, but it is speculated as follows.

In the present invention, by printing the inkjet ink on the pretreatment layer formed by the pretreatment liquid, the organic acid is dissolved and diffused from the pretreatment layer to the inkjet ink to aggregate and immobilize the pigment, thereby causing bleeding and bleeding. We believe that poor adhesion will be suppressed. Therefore, it is preferable that the higher the printing speed, the higher the dissolution / diffusion speed of the organic acid in the inkjet ink. In order to increase the dissolution / diffusion rate of the organic acid, the resin of the pretreatment layer may be swollen or dissolved by the inkjet ink. On the other hand, it is presumed that if the swellability or solubility is too high, a uniform film cannot be formed and adhesion cannot be obtained. In the composite resin particles having a polyurethane structure, the polyol component contained in the structure is appropriately swollen by the organic solvent contained in the inkjet ink to promote the diffusion of the organic acid, and the hard segment of the isocyanate component makes the film state uniform. We believe that it is possible to secure adhesion by maintaining the above. Further, it is particularly preferable that the polyol component has a polycarbonate structure or a polyether structure in terms of storage stability of the pretreatment liquid.

It is preferable that the flocculant is present in the pretreatment liquid in the range of 0.1 to 20% by mass in that the anionic component in the inkjet ink can be effectively aggregated.

The content of the flocculant in the water-soluble substance can be measured by a known method. For example, when the flocculant is a polyvalent metal salt, the content can be measured by ICP emission spectrometry, and when the flocculant is an acid, the content can be measured by high performance liquid chromatography (HPLC).

When an organic acid is used, the amount of the organic acid applied is preferably an amount that adjusts the pH of the pretreatment liquid to be equal to or less than the neutralization equivalent of the anionic component contained in the inkjet ink. When the anion component is a compound having a carboxy group, the first dissociation constant of the organic acid is preferably 3.5 or less from the viewpoint of making image blurring less likely to occur.

The amount of the pretreatment liquid of the present invention is not particularly limited and can be adjusted as appropriate. For example, when the flocculant is a polyvalent metal salt, the amount of the polyvalent metal salt applied is preferably in the range of 0.1 to 20 g / m ² . When the flocculant is an organic acid, it is preferable that the amount of the organic acid applied is equal to or less than the neutralization equivalent of the anionic component in the water-soluble ink.

(Water and other additives)
The water contained in the pretreatment liquid according to the present invention is not particularly limited, and may be ion-exchanged water, distilled water, or pure water.

Further, as the solvent of the pretreatment liquid according to the present invention, an organic solvent can be contained in addition to water. The solvent can be removed when the pretreatment liquid in the subsequent stage is dried.

In addition, other components such as a surfactant, a cross-linking agent, an antifungal agent, and a bactericide can be appropriately added to the pretreatment liquid as long as the effects of the present invention are not impaired.

Various additives can be added to the pretreatment liquid. Among them, the cationic mordant is preferable for improving the water resistance and moisture resistance after printing.

As the cation mordant, a polymer mordant having a primary to tertiary amino group and a quaternary ammonium base is preferably used, but discoloration and deterioration of light resistance over time are small, and the mordant ability of the dye is sufficiently high. Therefore, a polymer mordant having a quaternary ammonium base is preferable. Preferred polymer mordants are obtained as homopolymers of the above-mentioned quaternary ammonium base-containing monomers, copolymers with other monomers, or reduced polymers. Specific examples of the cationic mordant are described in, for example, "Inkjet Printer Technology and Materials" on page 268 (CMC).

Further, for example, the ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988 and JP-A-62-261476, JP-A-57-74192, JP-A-57-87989, JP-A-60. Anti-fading agents, various anionic, cation or nonionic surfactants described in JP-A-72785, JP-A-61-146591, JP-A-1-95091, JP-A-3-13376, etc., JP-A-59. Lubricant of fluorescent whitening agent, antifoaming agent, diethylene glycol, etc. Various known additives such as agents, preservatives, thickeners, antistatic agents and the like can also be contained.

It is preferable to prepare the pretreatment layer by directly applying and drying the pretreatment liquid according to the present invention on the substrate as a coating liquid. Here, it is preferable that the additive preferably used in the pretreatment liquid is sufficiently dispersed before being used as the coating liquid.

As a method for applying the pretreatment liquid, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or an extrusion coating method using a hopper described in US Pat. No. 2,681,294 is preferably used.

(Base material)
The substrate that can be used in the present invention is a low-absorbent substrate or a non-absorbent substrate. In the present invention, the absorbability means the absorbability to water.

Examples of the low-absorbent base material include non-coated paper such as stencil paper, medium-quality paper, and high-quality paper; coated paper such as coated paper, art paper, and cast paper.

As an example of the non-absorbent base material, a known plastic film can be used. Specific examples include polyester films such as polyethylene terephthalate, polyethylene films, polypropylene films, polyamide films such as nylon, polystyrene films, polyvinyl chloride films, polycarbonate films, polyacrylonitrile films, and biodegradable films such as polylactic acid films. Can be mentioned. Further, in order to impart gas barrier property, moisture resistance, fragrance retention and the like, a film coated with polyvinylidene chloride on one or both sides of a film or a film on which a metal oxide is vapor-deposited can also be preferably used. As the non-water-absorbent film, either an unstretched film or a stretched film can be preferably used. Among these, a polyester film is preferable, and a polyethylene terephthalate film is more preferable, from the viewpoint of heat resistance.

In the present invention, the thickness of the substrate is preferably in the range of 10 to 120 μm, more preferably 12 to 60 μm.

The surface of the base material may be surface-treated in order to control wettability and gas permeability.

[Inkjet ink]
The inkjet ink (also simply referred to as “ink”) according to the inkjet recording liquid set of the present invention contains at least a pigment, a pigment dispersant, a water-soluble organic solvent, and water.

(Pigment)
As the pigment contained in the inkjet ink, an anionic dispersed pigment, for example, an anionic self-dispersing pigment or a pigment dispersed with an anionic polymer dispersant can be used, and in particular, anionic. It is preferable to disperse the pigment with the polymer dispersant of.

As the pigment, conventionally known pigments can be used without particular limitation, and for example, organic pigments such as insoluble pigments and lake pigments, and inorganic pigments such as titanium oxide can be preferably used.

It should be noted that, in titanium oxide, where it is generally difficult to secure ink ejection stability and adhesion, the present invention makes it possible to particularly preferably prevent bleeding and improve adhesion.

Titanium oxide has three crystal forms of anatase type, rutile type and blue kite type, and general-purpose ones can be roughly classified into anatase type and rutile type. Although not particularly limited, the rutile type having a large refractive index and high concealing property is preferable. Specific examples include the TR series of Fuji Titanium Industry Co., Ltd., the JR series of TAYCA Corporation, and the type of Ishihara Sangyo Co., Ltd.

The insoluble pigment is not particularly limited, but is not limited to, for example, azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindoline, isoindoline, azine, oxazine, thiazine, and the like. Dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole and the like are preferable.

Specific organic pigments that can be preferably used include the following pigments.

Pigments for magenta or red include, for example, C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 16, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139, C.I. I. Pigment Red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, C.I. I. Pigment Red 202, C.I. I. Pigment Red 222, C.I. I. Pigment Violet 19 and the like.

Examples of the pigment for orange or yellow include C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 15: 3, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 128, C.I. I. Pigment Yellow 94, C.I. I. Pigment Yellow 138, C.I. I. Pigment Yellow 155 and the like. Especially in the balance between color tone and light resistance, C.I. I. Pigment Yellow 155 is preferred.

Examples of the pigment for green or cyan include C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 and the like.

Further, as a pigment for black, for example, C.I. I. Pigment Black 1, C.I. I. Pigment Black 6, C.I. I. Pigment Black 7 and the like.

(Pigment dispersant)
The pigment dispersant used for dispersing the pigment is not particularly limited, but a polymer dispersant having an anionic group is preferable, and those having a molecular weight of 5000 or more and 200,000 or less can be preferably used.

The polymer dispersant was selected from, for example, styrene, styrene derivative, vinylnaphthalene derivative, acrylic acid, acrylic acid derivative, maleic acid, maleic acid derivative, itaconic acid, itaconic acid derivative, fumaric acid, and fumaric acid derivative2. Examples thereof include block copolymers having a structure derived from the above-mentioned monomers, random copolymers and salts thereof, polyoxyalkylenes, polyoxyalkylene alkyl ethers and the like.

The polymer dispersant preferably has an acryloyl group, and is preferably added after being neutralized with a neutralizing base. Here, the neutralizing base is not particularly limited, but is preferably an organic base such as ammonia, monoethanolamine, diethanolamine, triethanolamine, and morpholine. In particular, when the pigment is titanium oxide, it is preferable that the titanium oxide is dispersed with a polymer dispersant having an acryloyl group.

The amount of the polymer dispersant added is preferably 10 to 100% by mass, more preferably 10 to 40% by mass, based on the pigment.

The pigment is particularly preferably in the form of a so-called capsule pigment in which the pigment is coated with the polymer dispersant. As a method for coating the pigment with the polymer dispersant, various known methods can be used. For example, a phase inversion emulsification method, an acid analysis method, or a method in which the pigment is dispersed with a polymerizable surfactant is used. A method of supplying a monomer to the polymer and coating it while polymerizing can be preferably exemplified.

As a particularly preferable method, a water-insoluble resin is dissolved in an organic solvent such as methyl ethyl ketone, the acidic groups in the resin are partially or completely neutralized with a base, and then a pigment and ion-exchanged water are added and dispersed. After that, a method of removing the organic solvent and adding water as needed can be mentioned.

The average particle size of the pigment in the dispersed state in the inkjet ink is preferably 50 nm or more and less than 200 nm. As a result, the dispersion stability of the pigment can be improved, and the storage stability of the inkjet ink can be improved. The particle size of the pigment can be measured by a commercially available particle size measuring device using a dynamic light scattering method, an electrophoresis method, etc., but the measurement by the dynamic light scattering method is simple and the particle size region can be measured. It can be measured accurately.

The pigment can be dispersed and used by a disperser together with a dispersant and other additives necessary for various purposes.

As the disperser, a conventionally known ball mill, sand mill, line mill, high-pressure homogenizer, or the like can be used. Above all, it is preferable to disperse the pigment by a sand mill because the particle size distribution becomes sharp. The material of the beads used for the dispersion of the sand mill is not particularly limited, but is preferably zirconia or zircon from the viewpoint of preventing the formation of bead fragments and the contamination of ionic components. Further, the bead diameter is preferably 0.3 to 3 mm.

The content of the pigment in the inkjet ink is not particularly limited, but is preferably in the range of 7 to 18% by mass for titanium oxide and 0.5 to 7% by mass for the organic pigment.

(Water-soluble organic solvent)
Known water-soluble organic solvents contained in the inkjet ink include, for example, alcohols, polyhydric alcohols, amines, amides, glycol ethers, 1,2-alkanediols having 4 or more carbon atoms, and the like. A water-soluble organic solvent can be used. The water-soluble organic solvent can be removed when the pretreatment liquid is dried.

(Water and other additives)
The water contained in the inkjet according to the present invention is not particularly limited, and may be ion-exchanged water, distilled water, or pure water.

The inkjet ink according to the present invention is known, if necessary, for the purpose of improving surfactant, emission stability, print head or ink cartridge compatibility, storage stability, image storage property, and other various performance improvements. Various additives can be contained.

[Inkjet recording method]
The inkjet recording method of the present invention is characterized by using the above-mentioned inkjet recording liquid set. In the method using this inkjet recording liquid set, for example, before forming the inkjet recording liquid set of the present invention on the surface of a low-absorption substrate or a non-absorbent substrate by using one inkjet printer. The application of the treatment liquid and the printing with ink can be continuously and efficiently performed. Then, it becomes possible to print characters, patterns, etc. with excellent image quality with little variation in dot diameter between the base materials.

For example, when printing full-color characters and patterns by the inkjet printing method, there are four colors, cyan (C), magenta (M), yellow (Y), and black (K), or light cyan (LC) and light. An ink set containing six colors of ink to which magenta (LM) is added and a pretreatment liquid is filled in an ink supply unit (ink cartridge or the like) of one inkjet printer.

Then, first, from the supply unit filled with the pretreatment liquid, the pretreatment liquid is printed on the surface of the non-absorbable base material such as the polyolefin-based plastic with ink to print arbitrary characters, patterns, etc. through the nozzle of the head. It is applied to the region or substantially the entire surface of the surface to form a pretreatment liquid layer.

Next, the pretreatment liquid layer is dried as necessary, and then ink of each color is applied to the surface of the pretreatment liquid layer from each supply unit through a nozzle of the head in the same manner as in a normal inkjet printing method. Arbitrary characters, patterns, and the like can be printed on the surface of the non-absorbent substrate by sequentially and intermittently ejecting them in correspondence.

The inkjet head that can be used in the present invention may be an on-demand method or a continuous method. The discharge method includes an electric-mechanical conversion method (for example, single cavity type, double cavity type, bender type, piston type, shared mode type, shared wall type, etc.) and an electric-heat conversion method (for example, thermal inkjet). Any discharge method such as type, bubble jet (registered trademark) type, etc. may be used.

The transport speed of the recording medium can be set, for example, between 1 m / min and 120 m / min. The faster the transport speed, the faster the image formation speed. According to the present invention, an image that further suppresses the occurrence of bleeding and has high adhesion even at a very high linear velocity of 50 m / min or more and 120 m / min or less, which can be applied by a single-pass inkjet image forming method. Can be obtained.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. Although the display of "parts" or "%" is used in the examples, it represents "parts by mass" or "% by mass" unless otherwise specified.

[Example 1]
《Inkjet ink》
[Pigment dispersion]
Pigment dispersions 1 to 4 in which the pigment (Pigment Yellow 155) was dispersed in the pigment dispersant, which was prepared as follows, were used.

(Preparation of Pigment Dispersion Liquid 1)
Polymer dispersant having an acryloyl group as a polymer dispersant (TEGO Dispers 715W, acid value 120, active ingredient 40% by mass, manufactured by Evonik Tego Chemie) 31.5% by mass, pigment blue 15: 3 as a pigment 18% by mass After premixing a mixed solution containing 20% by mass of ethylene glycol and ion-exchanged water (remaining; an amount that makes the total amount 100% by mass) as the balance, 0.5 mm zirconia beads were filled in a volume ratio of 50%. The pigment dispersion liquid 1 having a pigment content of 18% by mass was prepared by dispersing using a sand grinder. The average particle size of the pigment particles contained in the pigment dispersion liquid 1 was 128 nm. The particle size was measured with a Zetasizer 1000HS manufactured by Malvern.

(Preparation of Pigment Dispersion Liquid 2)
As a polymer dispersant, a styrene / acrylic acid copolymer (John Krill 678, molecular weight 8500, acid value 215, manufactured by BASF, "John Krill" is a registered trademark of the same company) 3.0% by mass, pigment (pigment yellow 155) After premixing a mixed solution containing 15% by mass and ion-exchanged water as the balance, the mixture was dispersed using a sand grinder filled with 0.5 mm zirconia beads at a volume ratio of 50%, and the pigment content was 15% by mass. Pigment dispersion liquid 2 of the above was prepared. The average particle size of the pigment particles contained in the pigment dispersion liquid 2 was 122 nm. The particle size was measured in the same manner as in Pigment Dispersion Liquid-1.

(Preparation of Pigment Dispersion Liquid 3)
In the preparation of the pigment dispersion liquid 1, EFKA5071 (alkylol ammonium salt of unsaturated carboxylic acid manufactured by Ciba, acid value 90, amine value 100) was used as the polymer dispersant, and the pigment was dispersed in the same manner as in the preparation of the pigment dispersion liquid 1. Liquid 3 was prepared. The average particle size of the pigment particles contained in the pigment dispersion liquid 3 was 130 nm. The particle size was measured in the same manner as in the pigment dispersion liquid 1.

(Preparation of Pigment Dispersion Liquid 4)
In the preparation of the pigment dispersion liquid 1, the pigment dispersion liquid 4 was prepared in the same manner as the preparation of the pigment dispersion liquid 1 except that J6102B (acrylic acid copolymer acid value 65 Tg19 manufactured by BASF) was used as the polymer dispersant. bottom. The average particle size of the pigment particles contained in the pigment dispersion liquid 4 was 126 nm. The particle size was measured in the same manner as in the pigment dispersion liquid 1.

<< Preparation of Inkjet Ink 1 >>
While stirring the pigment dispersion liquid 1 prepared above, each of the additives shown below is sequentially added so that the solid content becomes 5.0 parts by mass to prepare an ink composition, and then a 0.8 μm filter is used. Ink was obtained by filtration. There was no substantial change in composition before and after filtration.

Pigment solid content 5.0 parts by mass Ethylene glycol 30.0 parts by mass Surfactant (Orfin E1010 manufactured by Nisshin Kagaku Kogyo Co., Ltd.) 1.0 part by mass Ion-exchanged water total amount is 100.0 parts by mass

<< Preparation of inkjet inks 2-4 >>
In the preparation of inkjet 1, the pigment dispersion and the water-soluble organic solvent were changed as shown in Table I to obtain the inkjet ink No. 2-4 were prepared.

《Pretreatment liquid》
[Water-insoluble resin fine particles]
The non-urethane-based (R1 and R2) and urethane-based (R3 and R4) water-insoluble resin fine particles described below were used. The R4: urethane-olefin composite resin 1 is a composite resin fine particle obtained by emulsifying a polyolefin resin into a polyurethane resin, and was synthesized by the following method.

R1: Viniblanc 2687 (manufactured by Nissin Chemical Industry Co., Ltd.)
R2: Auroran AE202 (manufactured by Nippon Paper Industries, Ltd.)
R3: Superflex 650 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)
R4: Urethane / olefin composite resin 1
(R4: Synthesis of urethane / olefin composite resin 1)
<1. Synthesis of urethane polymer solution U-1>
In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer and a nitrogen blowing tube, 182 parts by mass of polyester polyol (trade name: Tesslac 2461, manufactured by Hitachi Chemical Co., Ltd.) and polyethylene glycol (PEG, molecular weight 600) are added. , Trade name PEG600, Daiichi Kogyo Seiyaku Co., Ltd., 22.0 parts by mass, trimethylolpropane, 5.6 parts by mass, N-methyl-N, N-diethanolamine, 43.8 parts by mass, 4 , 4'-Dicyclohexylmethane diisocyanate in 204 parts by mass and 216 parts by mass of methyl ethyl ketone (MEK) in a reaction vessel (addition amount of tertiary amine 9.6% by mass, addition amount of PEG 4.8% by mass), 75 ° C. The reaction was carried out while keeping the temperature in place to obtain a urethane prepolymer.

46.4 parts by mass of dimethyl sulfate is added to this urethane prepolymer and reacted at 50 to 60 ° C. for 30 to 60 minutes to obtain a urethane prepolymer solution having an NCO content of 2.2% and a non-volatile content of 50%. I got U-1.

<2. Preparation of Urethane / Olefin Composite Resin 1>
Polyolefin resin (trade name: Aurolen 150S, manufactured by Nippon Paper Industries, Ltd. (denoted as "150S" in Table I)) in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube. ) 3.0 parts by mass, 240.0 parts by mass of methylcyclohexane and 48.0 parts by mass of methylethylketone were added, and the temperature was raised to 80 ° C. to dissolve them by heating. After dissolution, the internal temperature was maintained at 40 ° C., and 194 parts by mass of urethane polymer solution U-1 (nonvolatile content of about 50%) was added and mixed. 58.0 parts by mass of water was added to this solution, emulsified using a homogenizer, and then 570 parts by mass of water was gradually added to dilute the solution, and 1.0 part by mass of ethylenediamine and 12 parts by mass of water were mixed. Aqueous solution was gradually added and stirred for 1 hour for polymerization. This was desolvated under reduced pressure at 50 ° C. to obtain a urethane-olefin composite resin 1 having a non-volatile content (solid content as particles) of 30% by mass.

[Surfactant]
The following surfactants S1 to S6 were used. S1 to S3 are silicone-based surfactants according to the present invention, and S1 to S3 were synthesized by the following synthesis method. S4 is not a silicone-based surfactant according to the present invention, and S5 and S6 are non-silicone surfactants, both of which are comparative surfactants.

S1: A silicone-based surfactant according to the present invention, which was synthesized by the following synthetic method.

S2: A silicone-based surfactant according to the present invention, which was synthesized by the following synthetic method.

S3: A silicone-based surfactant according to the present invention, which was synthesized by the following synthetic method.

S4: BYK333 (manufactured by Big Chemie Japan Co., Ltd.)
S5: Surfinol 465 (manufactured by Nissin Chemical Industry Co., Ltd.)
S6: Emargen 706 (manufactured by Kao Corporation)
(Synthesis example of silicone-based surfactant S1)
In a five-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer and a nitrogen blowing tube, 450 parts by mass of allylated polyether (Uniox PKA-5008 manufactured by Nichiyu Co., Ltd.) and H2Pt16.6H2O Hexachloroplatinum (IV) acid hexahydrate (manufactured by Tokyo Chemical Industry Co., Ltd.) was charged with 0.01 parts by mass and subjected to nitrogen substitution. The mixture was heated to 70 ° C., 220 parts by mass of heptamethyltrisiloxane (manufactured by Aldrich) was added dropwise over 1 hour, and then the reaction vessel was heated to 110 ° C. and reacted for 4 hours. After the reaction, the unreacted material was distilled off under reduced pressure to obtain a silicone-based surfactant S1 which is a target silicone-based surfactant. The obtained silicone-based surfactant S1 is a silicone-based surfactant corresponding to R = methyl group, X = alkylene group having 3 carbon atoms, m = 9, and n = 0 in the general formula (1).

(Synthesis example of silicone-based surfactant S2)
In the synthetic example of the silicone-based surfactant S1, instead of 450 parts by mass of an allylated polyether (Uniox PKA-5008 manufactured by Nichiyu Co., Ltd.), an allylated polyether (Unisafe PKA-5001 manufactured by Nichiyu Co., Ltd.) A silicone-based surfactant S2 was obtained in the same manner as in the synthesis example of the silicone-based surfactant S1 except that 200 parts by mass was used. The obtained silicone-based surfactant S2 is a silicone-based surfactant corresponding to R = hydrogen atom, X = alkylene group having 3 carbon atoms, m = 3, and n = 0 in the general formula (1).

(Synthesis example of silicone-based surfactant S3)
In the synthesis example of the silicone-based surfactant S1, instead of 450 parts by mass of the allylated polyether (Uniox PKA-5008 manufactured by Nikko Co., Ltd.), the allylated polyether (Unisafe PKA-5011 manufactured by Nikko Co., Ltd.) A silicone-based surfactant S3 was obtained in the same manner as in the synthesis example of the silicone-based surfactant S1 except that 200 parts by mass was used. The obtained silicone-based surfactant S3 is a silicone-based surfactant corresponding to R = hydrogen atom, X = alkylene group having 3 carbon atoms, m = 12, and n = 3 in the general formula (1).

[Coagulant]
The following flocculants were used.

F1: Malic acid F2: Calcium chloride F3: PAS-H-1L (cationic allylamine-based resin: manufactured by Nittobo Medical Co., Ltd.)

<< Preparation of pretreatment liquid 1 >>
Each of the additives shown below was added sequentially with stirring, and then filtered through a 5.0 μm filter to obtain a pretreatment liquid. There was no substantial change in composition before and after filtration.

Water-insoluble resin fine particles R1 (Viniblanc 2687) 14.0 parts by mass Silicone surfactant S1 1.0 part by mass Aggregator: PAS-H-1L 5.0 parts by mass The total amount of ion-exchanged water is 100.0 parts by mass. Amount << Preparation of pretreatment liquids 2 to 19 >>
As shown in Table II, pretreatment liquids 2 to 19 were prepared in the same manner as in the pretreatment liquid 1 except that the types of water-insoluble resin fine particles and the types and addition amounts of the surfactant and the flocculant were changed.

<< Formation of pretreatment layer >>
The following four types were used as the base material, and the pretreatment liquids 1 to 19 prepared above were applied using bar coater # 10, and then the mixture was ring-dried at 60 ° C. to a thickness of 3.2 μm. A recording medium having a layer on each substrate was prepared.

〔Base material〕
Coated paper 1: OK Top coat + (Basis weight 105 g / m ² , manufactured by Oji Paper Co., Ltd.)
Coated paper 2: Mirror coated paper Platinum (cast coated paper (mirror coated platinum, basis weight 157 g / m ² , manufactured by Oji Paper Co., Ltd.))
PET: Polyester film with a thickness of 50 μm (Taiko polyester 50 μm manufactured by Futamura Chemical Co., Ltd.)
OPP: Stretched polypropylene film (OPP-AQ 60 μm manufactured by Futamura Chemical Co., Ltd.)

[Preparation of print sample]
Next, an ink droplet volume 7. Under the condition that the recording density is 900 dpi using three heads of 5 pl and 300 dpi, the blank characters (5 point, 6 point, 7 point characters) formed by not ejecting the ink in the solid image are printed on the stage. The scanning speed was 50 m / min, and printing was performed by one scan. Similarly, a solid image was printed by one scan at a linear speed of 50 m / min under the condition that the recording density was 900 dpi using three heads of 300 dpi. The dpi in the present specification represents the number of dots per 2.54 cm. The ink droplet volume was controlled by adjusting the injection voltage for each ink. The environment for inkjet printing was a room temperature of 25 ° C., and the temperature of the recording medium was also 25 ° C.

The combination of the pretreatment liquid and the inkjet ink was printed on each recording medium under the above conditions with the combination of the inkjet ink, the pretreatment liquid and the recording medium as shown in Table II.

"evaluation"
The evaluation was made based on the coatability when each pretreatment liquid was applied to the above four types of substrates, unevenness after printing with inkjet ink, dot diameter, and bleeding of characters.

[Applicability / concentration unevenness]
The presence or absence of cissing when the pretreatment liquid was applied using the bar coater # 10 was visually confirmed. Repellent means that unevenness is formed because a portion that could not be applied is formed on the base material due to poor coatability. The following three stages of visual evaluation were performed.
A: No repellency is observed B: Slight cissing Was not observed, the B-ranked ones showed slight density unevenness, and the C-ranked ones had density unevenness on the entire surface.

[Dot diameter]
Images for dot diameter measurement arranged at intervals of 300 dpi were separately printed and fixed in the same manner as solid images. The diameters of the dots formed by the ejected droplets were measured by 20 pieces using an optical microscope (VHX-500 manufactured by KEYENCE), the arithmetic mean value was obtained, and the following ranking was performed. The larger the dot diameter, the better.
AA: 55 μm or more A: 50 μm or more and less than 55 μm B: 45 μm or more and less than 50 μm C: less than 45 μm

[Blur]
The omitted character portion of the obtained recorded material was evaluated according to the following criteria from the character size that can be recognized at a distance of 30 cm without blurring due to bleeding.
A: Up to 5 point characters can be recognized B: Up to 6 point characters can be recognized C: Up to 7 point characters can be recognized The above results are shown in Table II.

From Table II, when the inkjet recording liquid set using the silicone-based surfactants S1 to S3 according to the present invention as the pretreatment liquid was used, there was little unevenness, the dot diameter was large, and the variation between the base materials was small. It can be seen that good results are obtained with less bleeding. Further, it is better when the composite resin fine particles R4 in which the urethane-based particularly polyolefin-based resin is emulsified into the polyurethane-based resin is used as compared with the case where the non-urethane-based water-insoluble resin fine particles R1 and R2 are used as the pretreatment liquid. It can be seen that various results can be obtained.

Claims (3)

An inkjet recording liquid set containing at least an inkjet ink and a pretreatment liquid, which uses a low-absorbing base material or a non-absorbent base material as a recording medium.
The inkjet ink contains at least a pigment, a pigment dispersant, a water-soluble organic solvent, and water.
The pretreatment liquid contains at least composite resin fine particles obtained by emulsifying a polyolefin resin into a polyurethane resin, a flocculant, and a silicone-based surfactant, and
The silicone-based surfactant contained in the pretreatment liquid has a structure represented by the following general formula (1), and the addition amount is 0.5 to 3.0% by mass with respect to the pretreatment liquid. An inkjet recording liquid set characterized by being in the range of .

(In the formula, R represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms. X is an alkylene group having 2 to 6 carbon atoms and may have a branched structure. EO is poly. Represents the repeating unit structure of ethylene oxide. PO represents the repeating unit structure of polypropylene oxide. The order of [EO] _m and [PO] _n may be either. N and m represent the number of repeating unit structures. , M is an integer of 2 to 50, and n is an integer of 0 to 20.) The inkjet recording liquid set according to claim 1, wherein the flocculant is a polyvalent metal salt or an organic acid. An inkjet recording method comprising the inkjet recording liquid set according to claim 1 or 2 .