阅读说明：本技术 Pp印刷材料及其制备方法和印刷机 (PP printing material, preparation method thereof and printer ) 是由 任明淑 盖树人 彭春宁 邢艳红 柳青 于 2021-09-22 设计创作，主要内容包括：本发明公开了一种PP印刷材料及其制备方法和印刷机,该PP印刷材料包括：PP基材；油墨接受层,所述油墨接受层涂覆在所述PP基材的至少一侧,其中,所述油墨接受层包括：水分散性树脂乳液、抗静电剂、热稳定剂、硅溶胶、消泡剂和表面活性剂。由此,该PP印刷材料不仅可以减薄油墨接受层的涂层厚度,降低材料成本,而且采用该PP印刷材料制备的印刷介质可以实现与橡皮布的良好分离,并且印刷后的图像各色对位精准,印刷效果优异。(The invention discloses a PP printing material, a preparation method thereof and a printer, wherein the PP printing material comprises the following components: a PP substrate; an ink receiving layer coated on at least one side of the PP substrate, wherein the ink receiving layer includes: water-dispersible resin emulsion, antistatic agent, heat stabilizer, silica sol, defoaming agent and surfactant. Therefore, the PP printing material can reduce the thickness of the coating of the ink receiving layer and reduce the material cost, and the printing medium prepared from the PP printing material can be well separated from a rubber blanket, and the printed images are accurate in alignment of various colors and excellent in printing effect.)

1. A PP printing material, comprising:

a PP substrate;

an ink receiving layer coated on at least one side of the PP substrate,

wherein the ink receiving layer includes: water-dispersible resin emulsion, antistatic agent, heat stabilizer, silica sol, defoaming agent and surfactant.

2. The PP printing material according to claim 1, wherein the ink receiving layer comprises 20 to 50 parts by weight of a water-dispersible resin emulsion, 1 to 10 parts by weight of an antistatic agent, 0.5 to 10 parts by weight of a heat stabilizer, 10 to 30 parts by weight of a silica sol, 10 to 50 parts by weight of an antifoaming agent, and 0.1 to 10 parts by weight of a surfactant.

3. The PP printing material according to claim 1 or 2, wherein the heat stabilizer has a melting point of 50 to 100 ℃;

optionally, the thermal stabilizer comprises at least one of a paraffin wax, a fatty acid, an ester, and a polyol.

4. The PP printing material according to claim 1 or 2, wherein the water-dispersible resin emulsion comprises at least one of an acrylic emulsion, a polyurethane emulsion, a styrene-acrylic emulsion, an ethylene copolymer emulsion, and an acrylic copolymer emulsion;

optionally, the antistatic agent comprises at least one of a polyphenolic acid, a phosphate ester salt, a silicone-based antistatic agent, and a polythiophene-based antistatic agent.

5. PP printing material according to claim 1 or 2, wherein the silica sol colloidal particles have an average particle size of not more than 100 nm.

6. The PP printing material according to claim 1 or 2, wherein the antifoaming agent comprises at least one of ethanol and n-butanol;

optionally, the surfactant comprises at least one of sodium lauryl sulfate, polyether surfactants, and silicone surfactants.

7. The PP printing material according to claim 1 or 2, wherein the ink receiving layer has a thickness of 0.1 to 5 μm.

8. A method for preparing the PP printing material according to any one of claims 1 to 7, comprising:

(1) mixing a water-dispersible resin emulsion, an antistatic agent, a heat stabilizer, silica sol, a defoaming agent and a surfactant to obtain an ink receiving layer coating liquid;

(2) the ink-receiving layer coating liquid is applied to at least one side of a PP base material, and then dried, so as to obtain a PP printing material.

9. The method according to claim 8, wherein in step (1), the heat stabilizer is paraffin or ethylene glycol stearate, which is pre-treated before mixing the water-dispersible resin emulsion, the antistatic agent, the heat stabilizer, the silica sol, the antifoaming agent, and the surfactant;

optionally, pre-treating the paraffin or ethylene glycol stearate comprises: adding 1-100 mL of hot water and 0.1-10 g of emulsifier under stirring based on 1g of paraffin or 1g of ethylene glycol stearate, and dispersing for 15-60 minutes to obtain a paraffin emulsion or an ethylene glycol stearate emulsion.

10. A printing machine, wherein the printing medium in the printing machine is prepared from the PP printing material as defined in any one of claims 1 to 7 or the PP printing material prepared by the method as defined in claim 8 or 9.

Technical Field

The invention belongs to the field of digital printing technology and images, and particularly relates to a PP printing material, a preparation method thereof and a printer.

Background

The HP Indigo color digital transfer printing technology is a new environment-friendly and efficient printing technology. The HP Indigo series digital printing machine relies on the color digital printing technology and the flow thereof, simultaneously provides the industry with the best printing quality, wide color gamut, variety of bearing objects, high speed, high efficiency and flexibility, and can variably print each printing copy and print hundreds of different pictures by typesetting once. HP Indigo printing has excellent image processing capabilities and ink coverage flexibility, comparable to, and even exceeding offset printing, and is also the best alternative for photographic silver halide applications.

The HP Indigo technology supports full color digital printing. Unlike conventional offset color printing presses, which require a complete printing unit for each color, HP Indigo digital presses are capable of performing multi-color printing in a single pass of the substrate. The HP Indigo digital press can transfer different images or inks on one set of blanket and imaging plate with each rotation of the press cylinder. Hewlett packard refers to this method or configuration as "instant color conversion".

All HP Indigo digital printing machines adopt unique liquid ink-ElectroInk of HP Indigo, ElectroInk forms images on rubber cloth, and transfers to printing medium in the form of film after drying, and in the printing process of every turn, rubber cloth-ink-printing medium three have a pressurized, heated contact process, when contacting, transfering, require printing medium and rubber cloth between the phenomenon of can not taking place to bond, the rubber cloth can not stick bad medium surface, the medium can also not damage, the adhesion rubber cloth at the same time. Therefore, the original copy of the printed image can be restored to the maximum extent only by the need of good matching among the ink, the flow and the printing medium, and the copying effect of the image is realized.

There are many types of printing media, and conventionally, recording papers having excellent water resistance, weather resistance, and durability have been proposed as various recording papers such as printing papers, poster papers, label papers, thermal recording papers, thermal transfer support papers, and electrophotographic recording papers. The PP synthetic paper has the characteristics of strong waterproofness, tear resistance, good printability, ultraviolet resistance, durability, economy, environmental protection and the like, so that the PP synthetic paper has wider application than common paper, and in recent years, the PP synthetic paper is gradually popularized as recording paper suitable for an electronic photograph printing mode.

Although the PP synthetic paper has a plurality of advantages, the surface energy of the PP synthetic paper is very low, ink cannot be transferred to the PP synthetic paper when the PP synthetic paper is directly printed, and an ink receiving layer needs to be coated on the surface of the PP synthetic paper; meanwhile, PP has the inherent defects of poor heat resistance and poor contraposition precision, and the imaging quality is influenced because the problem of inaccurate contraposition precision is easily caused in the high-temperature multicolor overprinting printing process.

Patent CN 110892010A uses PP synthetic paper as a support, and a recording paper having a surface treatment layer formed by applying a coating liquid containing an olefin copolymer emulsion on one or both surfaces of the support and drying the coating liquid, wherein the olefin copolymer particles derived from the emulsion in the surface treatment layer are softened by heating and fused with a liquid toner, thereby improving the adhesion between the recording paper and the liquid toner and the support. In order to solve the problem of thermal deformation, the patent adopts a method of thickening a coating, and although the deviation of the alignment precision is relieved to a certain extent, the material cost is greatly increased.

Patent CN106916326A discloses a printing material of synthetic paper and a preparation method thereof, and the printing coating formula of PP synthetic paper comprises modified water-based chlorinated polypropylene emulsion, which can increase the adhesion fastness of ink. However, this patent also fails to solve the problem of misalignment of the PP printing material.

Therefore, the existing PP printing material is in need of improvement.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, an object of the present invention is to provide a PP printing material, a method for preparing the same, and a printing press, wherein the PP printing material can not only reduce the thickness of the ink receiving layer and the material cost, but also can realize good separation between the printing medium prepared from the PP printing material and the blanket, and the printed image has accurate alignment of each color and excellent printing effect.

In one aspect of the invention, the invention provides a PP printing material. According to an embodiment of the invention, the PP printing material comprises:

a PP substrate;

an ink receiving layer coated on at least one side of the PP substrate,

wherein the ink receiving layer includes: water-dispersible resin emulsion, antistatic agent, heat stabilizer, silica sol, defoaming agent and surfactant.

According to the PP printing material provided by the embodiment of the invention, the ink receiving layer comprising the water-dispersible resin emulsion, the antistatic agent, the heat stabilizer, the silica sol, the defoaming agent and the surfactant is coated on the PP base material, wherein the heat stabilizer can absorb heat generated during printing and heating, the heat stabilizer is melted to generate phase change, and the temperature of the PP base material is kept not to rise in the phase change process, so that the heating elongation deformation of the PP base material is prevented, the printing alignment deviation phenomenon is eliminated, and the imaging quality is improved. Compared with the method for thickening the coating thickness in the prior art to relieve the contraposition deviation, the method has the advantage that the material cost is reduced by adding the heat stabilizer. The water-dispersible resin emulsion is used as a film-forming solvent and can be well compatible with a heat stabilizer, so that the ink receiving layer and the rubber stick are well separated, and the printing process is ensured to be smoothly carried out. Inorganic ions in the silica sol have high melting point, are not easy to deform during heating, can increase the roughness of an ink receiving layer, avoid the PP printing materials from being adhered when being stacked, and the silica sol has certain cohesiveness and can be matched with water-dispersible resin emulsion for use. In addition, the antistatic agent can improve the antistatic performance of the PP printing material, the defoaming agent can reduce the surface tension of bubbles in the ink receiving layer coating liquid, and the surfactant is favorable for the ink receiving layer coating liquid to be uniformly spread on a PP base material, so that the practicability of the PP printing material is further improved. Therefore, the PP printing material can reduce the thickness of the coating of the ink receiving layer and reduce the material cost, and the printing medium prepared from the PP printing material can be well separated from a rubber blanket, and the printed images are accurate in alignment of various colors, so that the printing effect is excellent.

In addition, the PP printing material according to the above embodiment of the present invention may further have the following additional technical features:

in some embodiments of the present invention, the ink receiving layer includes 20 to 50 parts by weight of a water-dispersible resin emulsion, 1 to 10 parts by weight of an antistatic agent, 0.5 to 10 parts by weight of a heat stabilizer, 10 to 30 parts by weight of a silica sol, 10 to 50 parts by weight of an antifoaming agent, and 0.1 to 10 parts by weight of a surfactant. This can improve the printing effect of the PP printing material.

In some embodiments of the present invention, the thermal stabilizer has a melting point of 50 to 100 ℃. Therefore, the thermal elongation deformation of the PP base material can be prevented, and the adhesion generated when the PP printing materials are stacked is avoided.

In some embodiments of the invention, the thermal stabilizer comprises at least one of a paraffin wax, a fatty acid, an ester, and a polyol. Therefore, the thermal elongation deformation of the PP base material can be prevented, and the adhesion generated when the PP printing materials are stacked is avoided.

In some embodiments of the present invention, the water-dispersible resin emulsion comprises at least one of an acrylic emulsion, a polyurethane emulsion, a styrene-acrylic emulsion, an ethylene copolymer emulsion, and an acrylic copolymer emulsion. Therefore, the ink receiving layer and the rubber roller can be well separated, and the printing process is ensured to be smoothly carried out.

In some embodiments of the invention, the antistatic agent comprises at least one of a polyalkenoic acid, a phosphate salt, a silicone-based antistatic agent, and a polythiophene-based antistatic agent. Thus, the antistatic performance of the PP printing material can be improved.

In some embodiments of the invention, the silica sol colloidal particles have an average particle size of no greater than 100 nm. Thus, the roughness of the ink receiving layer can be increased, the adhesion of PP printing materials when stacked on each other can be avoided, and the glossiness of the ink receiving layer can be further improved.

In some embodiments of the invention, the anti-foaming agent comprises at least one of ethanol and n-butanol.

In some embodiments of the present invention, the surfactant comprises at least one of sodium lauryl sulfate, polyether-based surfactants, and silicone-based surfactants.

In some embodiments of the present invention, the ink receiving layer has a thickness of 0.1 to 5 μm. Therefore, the production cost of the PP printing material is reduced.

In a second aspect of the invention, the invention proposes a method for preparing the above PP printing material. According to an embodiment of the invention, the method comprises:

(1) mixing a water-dispersible resin emulsion, an antistatic agent, a heat stabilizer, silica sol, a defoaming agent and a surfactant to obtain an ink receiving layer coating liquid;

(2) the ink-receiving layer coating liquid is applied to at least one side of a PP base material, and then dried, so as to obtain a PP printing material.

According to the method for preparing the PP printing material, the water-dispersible resin emulsion, the antistatic agent, the heat stabilizer, the silica sol, the defoaming agent and the surfactant are mixed to prepare the ink receiving layer coating liquid, wherein the heat stabilizer can absorb heat generated during printing and heating and is melted to generate phase change, and the temperature of the PP base material is kept not to rise in the phase change process, so that the heated elongation deformation of the PP base material is prevented, the printing alignment deviation phenomenon is eliminated, and the imaging quality is improved. Compared with the method for thickening the coating thickness in the prior art to relieve the contraposition deviation, the method has the advantage that the material cost is reduced by adding the heat stabilizer. The water-dispersible resin emulsion is used as a film-forming solvent and can be well compatible with a heat stabilizer, so that the ink receiving layer and the rubber stick are well separated, and the printing process is ensured to be smoothly carried out. Inorganic ions in the silica sol have high melting point, are not easy to deform during heating, can increase the roughness of an ink receiving layer, avoid the PP printing materials from being adhered when being stacked, and the silica sol has certain cohesiveness and can be matched with water-dispersible resin emulsion for use. In addition, the antistatic agent can improve the antistatic performance of the PP printing material, the defoaming agent can reduce the surface tension of bubbles in the ink receiving layer coating liquid, and the surfactant is favorable for the ink receiving layer coating liquid to be uniformly spread on a PP base material, so that the practicability of the PP printing material is further improved. Then, the ink-receiving layer coating liquid was applied to at least one side of the PP base material, and finally dried, so that a PP printing material was obtained. Therefore, the PP printing material prepared by the method can reduce the thickness of the coating of the ink receiving layer and reduce the material cost, and the printing medium prepared by the PP printing material can be well separated from a rubber blanket, and the alignment of various colors of the printed image is accurate, so that the printing effect is excellent.

In addition, the method for preparing a PP printing material according to the above embodiment of the present invention may further have the following additional technical features:

in some embodiments of the present invention, in step (1), the heat stabilizer is paraffin or ethylene glycol stearate, which is pre-treated in advance before mixing the water-dispersible resin emulsion, the antistatic agent, the heat stabilizer, the silica sol, the antifoaming agent, and the surfactant.

In some embodiments of the invention, in step (1), the pre-treating the paraffin or ethylene glycol stearate comprises: adding 1-100 mL of hot water and 0.1-10 g of emulsifier under stirring based on 1g of paraffin or 1g of ethylene glycol stearate, and dispersing for 15-60 minutes to obtain a paraffin emulsion or an ethylene glycol stearate emulsion.

In a third aspect of the invention, a printing press is provided. According to an embodiment of the present invention, the printing medium in the printing press is prepared from the PP printing material or the PP printing material prepared by the method. Therefore, the printing medium can be well separated from the rubber blanket in the printing machine, and the alignment of various colors of the printed image is accurate, so that the printing effect is excellent.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic structural diagram of a PP printing material according to one embodiment of the invention;

FIG. 2 is a schematic structural diagram of a PP printing material according to a further embodiment of the invention;

fig. 3 is a schematic flow chart of a method for preparing a PP printing material according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

The inventor finds that the printed image edge has 'color overflow' phenomenon after carefully observing when the printed image is printed on the PP material, so that the printed image can not be well restored. The inventor intensively studied the above, and found that the PP synthetic paper has different properties due to different production processes. The BOPP synthetic paper has the characteristics of higher mechanical strength, better transparency and glossiness, improved air tightness through material modification and the like, high cost performance, and good development space and application extensibility. The main resin of the BOPP synthetic paper is homopolymerized PP, and some functional additive master batches (antistatic master batch, pore-forming agent master batch, whitening master batch, extinction master batch and the like) are required to be added for further improving the application performance of the BOPP synthetic paper. The BOPP synthetic paper is generally three-layer or five-layer, and its production process includes extruding thick molten film from T-shaped die by extruder, cooling to obtain stretched sheet, heating the sheet to softening temperature, and stretching along longitudinal and transverse directions to form film. The longitudinal stretching ratio of the BOPP synthetic paper is generally 4.5-5.5 times, and the transverse stretching ratio is generally 8-10 times. After biaxial stretching, the polymer molecules arranged in a disordered way become more regular in orientation, so that the strength, rigidity and other properties of the BOPP synthetic paper are improved. Through a simulated printing experiment, the thermal expansion of the BOPP synthetic paper in the transverse and longitudinal directions at the printing temperature is measured, and the result shows that the BOPP synthetic paper is in an extension state in the transverse and longitudinal directions after being heated, and the longitudinal extension rate is greater than the transverse extension rate; the heated and cooled material shows a shortening phenomenon, and the longitudinal shortening is more obvious than the transverse shortening. In combination with the printing process analysis of the HP indigo digital printing machine, the inventor conjectures that due to the fact that the transverse and longitudinal stretching multiplying powers are different during production and preparation of the BOPP synthetic paper, the printing process has the effects of heating, pressurizing and drawing of a printing press roller, and therefore the longitudinal direction with small stretching multiplying power is further stretched during multi-color overprinting, and the phenomenon of printing alignment staggering occurs.

In order to solve the above problems, the inventors have made various attempts to integrate aspects of cost, performance, and the like. To this end, in one aspect of the invention, the invention proposes a PP printing material. According to an embodiment of the present invention, referring to fig. 1-2, the PP printing material comprises: a PP substrate 100; an ink receiving layer 200, wherein the ink receiving layer 200 is coated on at least one side of the PP substrate 100, and the ink receiving layer 200 comprises: water-dispersible resin emulsion, antistatic agent, heat stabilizer, silica sol, defoaming agent and surfactant.

The inventor finds that the thermal stabilizer can absorb heat generated during printing heating and melt to generate phase change, and the temperature of the PP base material is kept not to rise in the phase change process, so that the thermal elongation deformation of the PP base material is prevented, the printing alignment deviation phenomenon is eliminated, and the imaging quality is improved. Compared with the method for thickening the coating thickness in the prior art to relieve the contraposition deviation, the method has the advantage that the material cost is reduced by adding the heat stabilizer. The water-dispersible resin emulsion is used as a film-forming solvent and can be well compatible with a heat stabilizer, so that the ink receiving layer and the rubber stick are well separated, and the printing process is ensured to be smoothly carried out. Inorganic ions in the silica sol have high melting point, are not easy to deform during heating, can increase the roughness of an ink receiving layer, avoid the PP printing materials from being adhered when being stacked, and the silica sol has certain cohesiveness and can be matched with water-dispersible resin emulsion for use. In addition, the antistatic agent can improve the antistatic performance of the PP printing material, the defoaming agent can reduce the surface tension of bubbles in the ink receiving layer coating liquid, and the surfactant is favorable for the ink receiving layer coating liquid to be uniformly spread on a PP base material, so that the practicability of the PP printing material is further improved. Therefore, the PP printing material can reduce the thickness of the coating of the ink receiving layer and reduce the material cost, and the printing medium prepared from the PP printing material can be well separated from a rubber blanket, and the printed images are accurate in alignment of various colors, so that the printing effect is excellent.

Further, the ink receiving layer comprises 20-50 parts by weight of water dispersible resin emulsion, 1-10 parts by weight of antistatic agent, 0.5-10 parts by weight of heat stabilizer, 10-30 parts by weight of silica sol, 10-50 parts by weight of defoaming agent and 0.1-10 parts by weight of surfactant. The inventors have found that when the content of the water-dispersible resin emulsion is too small, the film-forming property of the coating is poor, and the bonding strength between the coating and the ink is liable to be poor; when the content of the water-dispersible resin emulsion is too large, the surface tackiness of the coating layer increases, resulting in blocking when the printed materials are stacked. When the content of the antistatic agent is too low, the surface resistance of the coating is too high, the electric conductivity is too poor, the residual potential on the printing material cannot be eliminated, the printing material is difficult to peel off from the selenium drum or the rubber blanket, and the printed sample pieces are sometimes bonded together, so that series paper path obstacles are caused; when the content of the antistatic agent is too much, a sufficient charging potential cannot be maintained in the printing process, the formation and stability of an electric field are influenced, the electric conductivity is too good or the transferred corona discharge is too fast, so that the ink cannot be transferred in time, and the printed image is unclear or the transfer is incomplete; when the content of the heat stabilizer is too low, the heat stabilizer cannot absorb enough heat in the printing process, so that PP (polypropylene) is heated and elongated to generate overprint deviation; when the heat stabilizer content is too large, the bonding fastness of the ink receptive coating layer to the ink is lowered. When the content of the silica sol is too low, the surface anti-sticking effect of the formed coating is poor, and the printing materials are easy to adhere to each other; when the content of the silica sol is too much, the formed coating has high brittleness, and a coating fracture trace is easy to generate to influence the printing effect; when the content of the defoaming agent is too low, the coating liquid has more bubbles during coating, and the appearance defects such as bubble streaks and the like are easily caused; when the content of the defoaming agent is too large, waste is caused, resulting in an increase in the cost of printing materials. When the content of the surfactant is too low, the coating liquid is not easy to spread on a PP (polypropylene) base material, and the coating defects such as edge folding and the like are easy to occur; when the content of the surfactant is too much, the surface energy of the coating is reduced, the transfer of the ink on the PP coating is influenced, and the printing problem of incomplete ink transfer is easy to occur. From this, adopt the oil film receiving layer of this application to constitute, the bonding fastness of coating and printing ink is good, and printing medium can realize the good separation with the blanket, can avoid printing material to take place the adhesion when stacking simultaneously, reduces material cost, and the printing effect is excellent.

Further, the heat stabilizer has a melting point of 50-100 ℃. The inventors have found that when the melting point temperature is lower than 50 ℃, the heat stabilizer is in a molten state in the coating layer, so that the coating layer is sticky and easy to generate blocking when being stacked; when the melting point temperature is higher than 100 ℃, the heat stabilizer can not melt and change phase when being heated during printing, and can not absorb heat. Therefore, the heat stabilizer within the melting point range can prevent the PP base material from being deformed by thermal elongation and avoid the adhesion generated when the PP printing materials are stacked. Preferably, the heat stabilizer comprises at least one of paraffin, fatty acid, ester and polyol. The inventor finds that the heat stabilizer belongs to an organic heat stabilizer, has large specific heat capacity, has good compatibility with a water-dispersible resin emulsion in an ink receiving layer, and when the heat stabilizer is added into a coating of the ink receiving layer, the heat stabilizer absorbs heat generated during printing and heating, starts to melt when reaching a melting point, generates phase change, only absorbs heat in the phase change process, but does not increase the temperature, and thus prevents the PP substrate from being elongated and deformed by heating.

Further, the average particle diameter of the silica sol colloidal particles is not more than 100nm, preferably not more than 30 nm. Specifically, the silica sol is a dispersion of nano-sized silica particles in water or a solvent, and the silica sol has a milky white or bluish white appearance and a translucent appearance, and the smaller the particle size of the colloidal particles, the better the transparency. The inventors found that if the colloidal particles of the silica sol have an average particle diameter of more than 100nm, the glossiness of the ink-receiving layer is lowered.

It should be noted that the specific types of the water-dispersible resin emulsion, the antistatic agent, the defoaming agent and the surfactant are not particularly limited, and can be selected by those skilled in the art according to actual needs, for example, the water-dispersible resin emulsion includes at least one of acrylic emulsion, polyurethane emulsion, styrene-acrylic emulsion, ethylene copolymer emulsion and acrylic copolymer emulsion, specifically, the ethylene copolymer emulsion is copolymerized by ethylene and at least one of styrene, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate and acrylic acid phosphate, and the acrylic copolymer emulsion is copolymerized by acrylic acid and at least one of ethylene, styrene-acrylic, styrene, acrylic acid ester and vinyl acetate; the antistatic agent comprises at least one of polyphenolic acid, phosphate ester salt, organosilicon antistatic agent and polythiophene antistatic agent; the antifoaming agent comprises at least one of ethanol and n-butanol; the surfactant includes at least one of sodium lauryl sulfate, polyether surfactants, and silicone surfactants.

Further, the ink receiving layer 200 has a thickness of 0.1 to 5 μm. The inventors found that when the ink-receiving layer is too thick, an increase in cost of the printing material is caused, and when the ink-receiving layer is too thin, a decrease in the bonding fastness of the ink to the coating layer is caused. Therefore, by adopting the thickness of the ink receiving layer, the bonding fastness of the ink and the coating is good, and the cost of printing materials is low.

In a second aspect of the invention, a method of making a PP printing material is presented. According to an embodiment of the invention, referring to fig. 3, the method comprises:

s100: mixing the water-dispersible resin emulsion, the antistatic agent, the heat stabilizer, the silica sol, the defoaming agent and the surfactant to obtain the ink receiving layer coating liquid

It should be noted that the specific types and mixing ratios of the water-dispersible resin emulsion, the antistatic agent, the heat stabilizer, the silica sol, the defoaming agent and the surfactant used in this step are the same as those described above, and are not described herein again.

According to one embodiment of the present invention, the heat stabilizer is paraffin or glycol stearate, which is pre-treated before mixing the water-dispersible resin emulsion, the antistatic agent, the heat stabilizer, the silica sol, the defoaming agent and the surfactant, so that the water-insoluble heat stabilizer can be blended with the water-soluble system for coating. Specifically, based on 1g of paraffin or 1g of ethylene glycol stearate, 1 to 100mL of hot water and 0.1 to 10g of emulsifier are added under stirring, and the mixture is dispersed for 15 to 60 minutes, so that paraffin emulsion or ethylene glycol stearate emulsion is obtained.

S200: applying an ink-receiving layer coating liquid to at least one side of a PP base material, followed by drying, so as to obtain a PP printing material

The application method of the ink-receiving layer coating liquid is not particularly limited, and may be selected by those skilled in the art according to actual needs, and may be, for example, a microgravure, a wire rod, a blade coating, or the like.

The inventor finds that the ink receiving layer coating liquid is prepared by mixing a water-dispersible resin emulsion, an antistatic agent, a heat stabilizer, silica sol, a defoaming agent and a surfactant, wherein the heat stabilizer can absorb heat generated during printing and heating, the heat stabilizer is melted to generate phase change, and the temperature of a PP (polypropylene) base material is kept not to rise in the phase change process, so that the heated elongation deformation of the PP base material is prevented, the printing alignment deviation phenomenon is eliminated, and the imaging quality is improved. Compared with the method for thickening the coating thickness in the prior art to relieve the contraposition deviation, the method has the advantage that the material cost is reduced by adding the heat stabilizer. The water-dispersible resin emulsion is used as a film-forming solvent and can be well compatible with a heat stabilizer, so that the ink receiving layer and the rubber stick are well separated, and the printing process is ensured to be smoothly carried out. Inorganic ions in the silica sol have high melting point, are not easy to deform during heating, can increase the roughness of an ink receiving layer, avoid the PP printing materials from being adhered when being stacked, and the silica sol has certain cohesiveness and can be matched with water-dispersible resin emulsion for use. In addition, the antistatic agent can improve the antistatic performance of the PP printing material, the defoaming agent can reduce the surface tension of bubbles in the ink receiving layer coating liquid, and the surfactant is favorable for the ink receiving layer coating liquid to be uniformly spread on a PP base material, so that the practicability of the PP printing material is further improved. Then, the ink-receiving layer coating liquid was applied to at least one side of the PP base material, and finally dried, so that a PP printing material was obtained. Therefore, the PP printing material prepared by the method can reduce the thickness of the coating of the ink receiving layer and reduce the material cost, and the printing medium prepared by the PP printing material can be well separated from a rubber blanket, and the alignment of various colors of the printed image is accurate, so that the printing effect is excellent.

It should be noted that the features and advantages described above for the PP printing material are also applicable to the method for preparing the PP printing material, and are not described herein again.

In a third aspect of the invention, a printing press is provided. According to an embodiment of the invention, the printing medium in the printing press is prepared from the PP printing material as described above or from a PP printing material prepared by the method as described above. Therefore, the printing medium can be well separated from the rubber blanket in the printing machine, and the alignment of various colors of the printed image is accurate, so that the printing effect is excellent. It should be noted that the features and advantages described above for the PP printing material and the method for making the same are also applicable to the printing press and will not be described in detail here.

The invention will now be described with reference to specific examples, which are intended to be illustrative only and not to be limiting in any way.

Example 1

30g of polyurethane emulsion, 1g of a polystyrenesulfonic acid antistatic agent, 10g of ethanol, 0.5g of trimethylolethane, 20g of silica sol (the average particle diameter of colloidal particles is not more than 100nm), and 0.1g of a sodium dodecyl sulfate surfactant were added to a vessel and stirred uniformly to prepare an ink-receiving layer coating solution. The coating liquid is coated on both sides of a corona PP substrate by using a coating rod, and the coating weight is 4.5g/m². Drying was carried out at 70 ℃ for 1 minute, and the coating thickness after drying was 1 μm.

Example 2

20g of acrylic emulsion, 10g of sodium phosphate antistatic agent, 30g of n-butyl alcohol, 10g of eicosanoic acid, 10g of silica sol (the average particle size of colloidal particles is not more than 100nm) and 10g of polyether 1283 surfactant are added into a container and uniformly stirred to prepare the ink receiving layer coating liquid. The coating liquid is coated on both sides of a corona PP substrate by using a coating rod, and the coating weight is 0.6g/m². Drying was carried out at 70 ℃ for 1 minute, and the coating thickness after drying was 0.1. mu.m.

Example 3

(1) 10g of paraffin with the melting point of 60 ℃ is heated and melted, and is added into a dispersion container filled with 85mL of hot water and 5g of alkyl sulfate emulsifier under the stirring state for dispersion for 30 minutes to prepare paraffin emulsion with the heat stabilizer content of 10 percent.

(2) Adding 35g of styrene-acrylic emulsion, 15g of ethylene copolymer emulsion, 5g of polythiophene antistatic agent, 50g of ethanol, 30g of silica sol (the average particle size of colloidal particles is not more than 100nm), 5g of organic silicon T-2 surfactant and 50g of paraffin emulsion into a container, and uniformly stirring to prepare the ink receiving layer coating liquid. The coating liquid is coated on both sides of a corona PP substrate by using a coating rod, and the coating weight is 30g/m². Drying was carried out at 70 ℃ for 5 minutes, the coating thickness being 5 μm after drying.

Example 4

(1) Heating and melting 3g of paraffin with the melting point of 90 ℃, adding the paraffin into a dispersion container filled with 96mL of hot water and 1g of alkyl sulfate emulsifier under the stirring state, and dispersing for 60 minutes to obtain paraffin emulsion with the heat stabilizer content of 10 wt%.

(2) 25g of acrylic copolymer emulsion, 10g of siloxane-polyoxyethylene antistatic agent, 30g of n-butanol, 15g of silica sol (the average particle size of colloidal particles is not more than 100nm), 3g of organosilicon T-6 surfactant and 20g of paraffin emulsion are added into a container and stirred uniformly to prepare the ink receiving layer coating liquid. The coating liquid is coated on both sides of a corona PP substrate by using a coating rod, and the coating weight is 15g/m². Drying at 70 deg.C for 3 minThe coating thickness after drying was 3 μm.

Example 5

(1) Heating and melting 3g of ethylene glycol stearate, adding the melted ethylene glycol stearate into a dispersing container filled with 87mL of hot water and 10g of Tween 60 emulsifier under the stirring state, and dispersing for 30 minutes to obtain the ethylene glycol stearate emulsion with the heat stabilizer content of 10 wt%.

(2) 25g of acrylic copolymer emulsion, 10g of potassium phosphate antistatic agent, 15g of ethanol, 15g of n-butanol, 15g of silica sol (the average particle diameter of colloidal particles is not more than 100nm), 3g of organosilicon T-6 surfactant and 20g of ethylene glycol stearate emulsion are added into a container and stirred uniformly to prepare the ink receiving layer coating liquid. The coating liquid is coated on both sides of a corona PP substrate by using a coating rod, and the coating weight is 15g/m². Drying was carried out at 70 ℃ for 3 minutes, the coating thickness being 3 μm after drying.

Comparative example

Adding 25g of acrylic copolymer emulsion, 10g of polythiophene antistatic agent, 30g of ethanol, 15g of silica sol and 3g of organic silicon T-6 surfactant into a container, and uniformly stirring to prepare the ink receiving layer coating liquid. The coating liquid is coated on both sides of a corona PP substrate by using a coating rod, and the coating weight is 15g/m². Drying was carried out at 70 ℃ for 3 minutes, the coating thickness being 3 μm after drying.

The samples of PP printing material coated in examples 1 to 5 and comparative example were tested as follows:

a) heat shrinkage test

The PP printing materials obtained in examples 1 to 5 and comparative example above were cut into blocks of 10 × 10cm size, marked in the horizontal and vertical directions, placed in an oven at 145 ℃, taken out after 5s and placed on a heating partition, and the lengths of the horizontal and vertical edges were measured and recorded by a micrometer. And calculating the thermal elongation of each PP synthetic paper in the transverse direction and the longitudinal direction.

b) Image printing alignment accuracy test

The PP printing materials obtained in the above examples 1 to 5 and comparative examples were cut into 320x464mm size, printed on the same channel on HP indigo3550 digital printer, observed under microscope and measured for printing alignment accuracy.

The test data for examples 1-5 and comparative examples are shown in table 1:

TABLE 1

	Example 1	Example 2	Example 3	Example 4	Example 5	Comparative example
							Transverse thousandth elongation	0.60	0.43	0.22	0.41	0.35	3.43
Longitudinal micro-elongation	1.08	0.98	0.45	1.02	0.89	3.86
							Lateral alignment precision mum	47.590	37.185	27.376	31.527	33.267	201.126
Longitudinal alignment precision mum	45.395	57.964	36.281	58.822	56.140	244.522

Note: the larger the value of the percent elongation in the table is, the more serious the PP deformation is; the larger the alignment accuracy value, the larger the alignment deviation.

As can be seen from Table 1, compared with the comparative examples, the PP printing material prepared by adding the heat stabilizer into the ink receiving layers of examples 1-5 has the advantages that the thermal deformation is effectively controlled, and the image alignment precision is obviously improved after indigo printing.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.