JPH0655826A - Offset printing sheet - Google Patents

Abstract

PURPOSE:To provide an offset printing sheet which is free from generation of set off at the time of the offset printing process, and superior ink setting properties, ink drying characteristics, ink adhesion, blocking resistance, antistatic properties and conveying properties at the time of printing. CONSTITUTION:In an offset printing sheet comprised by providing at least one side of a plastic film with a coating layer containing a resin ingredient and oil absorbing porous particles, mixed particles of the oil absorbing porous particles (A) having a mean particle diameter of 2.0 to 18.0mum and the oil absorbing porous particles (B) having the mean particle diameter of 0.3 to 4.0mum are used as the oil absorbing porous particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an offset printing sheet. More specifically, it relates to an offset printing sheet excellent in ink transferability, ink setting property, ink drying property, ink adhesion property, blocking resistance, antistatic property, and transportability during printing.

[0002]

2. Description of the Related Art In various printing sheets centering on offset printing, a paper support has been dominant in the past, but in recent years, a plastic film has begun to be used as a support. Also, among the plastic films, mechanical properties,
Polyester films having excellent properties such as transparency are becoming popular. However, in general, the surface of a polyester film has high cohesiveness and poor adhesiveness, and therefore, when various printing processes are performed on the surface, it is actively practiced to form an ink receiving layer having excellent ink affinity. As such a printing sheet, a printing sheet in which a surface layer containing n-butyl methacrylate as a main component is provided on at least one side of a support, for example, JP-A-1
No. 163093 is known.

[0003]

However, since such a printing sheet is inferior in blocking resistance and antistatic property, it has a problem in transportability during offset printing, and when it is subjected to general oil-based offset printing, Ink settability is poor. Further, when the printed matter is left in a stacked state in the offset printing process, there is a problem that set-off of ink occurs.

Therefore, according to the present invention, there is no occurrence of set-off of ink during the printing process, and the ink transfer property, ink setting property, ink drying property, ink adhesive property, blocking resistance, antistatic property, and transportability during printing are improved. It is an object to provide an excellent offset printing sheet.

[0005]

In order to achieve the above object, the present invention provides offset printing in which a coating layer containing a resin component and oil-absorbing porous particles is provided on at least one surface of a plastic film. Sheet, the oil-absorbing porous particles have an average particle diameter of 2.0 to 18.0 μm.
Oil-absorbing porous particles (A) and an average particle diameter of 0.3 to 4.
The gist of the present invention is a sheet for offset printing, which is a mixed particle of 0 μm oil-absorbing porous particles (B).

The plastic film referred to in the present invention means
Polyester, polyolefin, polyamide, polyester amide, polyether, polyimide, polyamide imide, polystyrene, poly-P-phenylene sulfide, polyether ester, polyvinyl chloride, poly (meth) acrylic acid ester and the like are preferable. Furthermore, these copolymers, blends, and further crosslinked products can be used. Among these plastic films, polyester film is preferable.

The polyester referred to in the present invention is a polymer obtained by polycondensation of a diol and a dicarboxylic acid, and examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, adipic acid, sebacic acid and the like. And the diols are ethylene glycol, trimethylene glycol, tetramethylene glycol, and cyclohexanedimethanol. Specific examples thereof include polyethylene terephthalate, polyethylene-P-oxybenzoate, poly-1,4-cyclohexylene dimethylene terephthalate, and polyethylene-2,6-naphthalene dicarboxylate. In the case of the present invention, polyethylene terephthalate and polyethylene naphthalate are particularly preferable. The polyethylene terephthalate film has excellent water resistance, durability and chemical resistance.

Of course, these polyesters may be homopolyesters or copolyesters. Examples of the copolymerization component include diol components such as diethylene glycol and polyalkylene glycol, and dicarboxylic acid components such as adipic acid, sebacic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid and 5-sodium sulfoisophthalic acid.

If desired, various known additives such as antioxidants and antistatic agents may be added to the polyester as long as the characteristics of the present invention are not impaired.

The thickness of the plastic film used in the present invention is preferably 10 μm to 300 μm. More preferably, it is from 15 μm to 200 μm, which is excellent in practical handling as a base material base.

The plastic film used in the present invention is
If necessary, known surface treatments such as corona discharge treatment, plasma discharge treatment, and anchor coating may be performed to improve the adhesiveness.

The oil-absorbing porous particles in the present invention are porous particles having pores on the surface of the particles, and can be freely filled with liquid, solid or gas in the form of hollow porous or non-hollow porous form. Those which can be released are preferable from the viewpoint of ink absorbency.

As constituents of the oil-absorbing porous particles, amorphous silica, anhydrous silica, aluminum silicate,
Magnesium silicate, zinc silicate, calcium silicate,
Hydrotalcite, zeolite, satin white, titanium oxide, aluminum oxide, magnesium oxide, calcium carbonate, calcium sulfate, barium sulfate, diatomaceous earth, kaolin, talc, acid clay, activated clay, bentonite, ion exchange resin powder, urea resin Powder, polyethylene resin powder, urea formalin resin powder, acrylic resin powder, styrene-acrylic resin powder and the like can be mentioned.

The oil absorption of these porous particles is 20
It is preferably 0 to 450 ml / 100 g. More preferably, it is 250 to 350 ml / 100 g. When the oil absorption is lower than the range of the present invention, the ink absorbency of the obtained offset printing sheet is poor, sufficient ink setting property, ink drying property cannot be obtained, and if it is higher than this, the obtained printed product becomes pale. Cheap.

The porous particles used in the present invention are oil-absorbing porous particles (A) having an average particle size of 2.0 to 18.0 μm.
And the oil-absorbing porous particles (B) having an average particle diameter of 0.3 to 4.0 μm. Use of only the oil-absorbing porous particles (A) is not preferable because the smoothness of the surface of the coating layer is remarkably reduced and the ink transfer property is deteriorated. Further, it is not preferable to use only the oil-absorbing porous particles (B), since there is no roughness on the surface of the coating layer to an appropriate degree, and there arises a problem in sticking property in the printing step, particularly ink set-off property.

The mixing ratio of the oil-absorbent porous particles (A) and (B) is preferably 10/90 to 90/10, more preferably 30/70 to 70/30.

The ratio A / B of the average particle diameters of the oil-absorbent polyphilic particles (A) and (B) is preferably 1.8 to 50.0,
It is more preferably 2.3 to 30.0, and even more preferably 2.6 to 15.0.

The content of the oil-absorbing porous particles in the coating layer is preferably 5-10 with respect to 100 parts by weight of the resin component.
It is 0 part by weight, more preferably 20 to 70 parts by weight.
If the content is less than 5 parts by weight, the ink setting property and the ink drying property will be insufficient, and if it exceeds 100 parts by weight, the adhesiveness between the coating layer and the film support tends to deteriorate.

The offset printing sheet of the present invention may contain a hiding white pigment for the purpose of imparting appropriate whiteness and hiding property. The hiding white pigment in the present invention is an inorganic or organic pigment that exhibits white in the coating layer, and examples of the inorganic pigment include zinc carbonate, zinc oxide, zinc sulfide, talc, kaolin, heavy / light or synthetic. Examples thereof include calcium carbonate, titanium oxide, silica, lithium fluoride, calcium fluoride, barium sulfate, alumina, zirconia, calcium phosphate, and natural or synthetic swelling or non-swelling mica. Examples of organic pigments include polystyrene, polyvinyl chloride,
Polyethylene, polypropylene, polyvinylidene chloride,
Examples thereof include poly (meth) acrylic acid copolymers, and at least one selected from these is applied.
Further, the pigment may be subjected to surface treatment, for example, treatment such as addition of a functional group such as a glycidyl group or a methylol group, in order to improve dispersibility in the resin component.

Further, the amount of the hiding white pigment added is preferably 5 to 100 parts by weight with respect to 100 parts by weight of the resin component,
More preferably, it is 10 to 60 parts by weight.

The resin component in the present invention may be selected from known ones and used. Among them, a reactive monomer-containing poly (meth) acrylic acid ester copolymer and a quaternary ammonium salt-containing cationic acrylic polymer are used. Those containing as a main component are preferable.

The reactive monomer of the reactive monomer-containing poly (meth) acrylic acid ester copolymer in the present invention can be selected from known ones and used, for example, acrylic acid,
Those having a carboxyl group such as methacrylic acid, itaconic acid, carboxyethyl acrylate and carboxyphenyl acrylate, hydroxyl groups such as 2-hydroxyethyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate Having (meth) acrylamide, N-
Those having an amide group such as methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, those having a glycidyl group such as glycidyl (meth) acrylate, 7
Examples thereof include those having an amino group such as -amino-3,7-dimethyloctyl (meth) acrylate, 2-dimethylaminoethyl (meth) acrylate, and 2-diethylaminoethyl (meth) acrylate.

The monomer unit of the poly (meth) acrylic acid ester copolymer in the present invention is, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl. Examples thereof include (meth) acrylate and hexyl (meth) acrylate.

A polymer electrolyte is added to the resin component in the present invention in order to adjust the electric resistance of the coating layer. In the present invention, the polymer electrolyte is a cationic acrylic polymer composed of a cationic monomer having a quaternary ammonium group, from the viewpoints of conductivity and compatibility with a reactive monomer-containing poly (meth) acrylic acid ester copolymer. Is preferably used. Examples of the cationic monomer having a quaternary ammonium group include 2-hydroxy-3-
(Meth) acryloxypropyltrimethylammonium chloride, 2-hydroxy-3- (meth) acryloxypropyltriethylammonium chloride, 2-
(Meth) acryloxyethyltrimethylammonium chloride, 2- (meth) acryloxyethyltriethylammonium chloride, vinylbenzyltrimethylammonium chloride, vinylbenzyltriethylammonium chloride, 4-vinyl-N-methylpyridinium chloride, N, N-dimethyl substitution -3,5-methylpiperidinium chloride, dimethyldiallylammonium chloride, diethyldiallylammonium chloride, ethyleneimine hydrochloride, and various quaternary ammonium salts and pyridinium salts described in the Handbook of Surfactants (Sangyo Tosho 1960). However, other cationic monomers having various known quaternary ammonium salts can be used.

In the present invention, these cationic monomers are used in the form of a copolymer with a (meth) acrylic acid ester. Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, and oxyl (meth) acrylate.

The electric resistance value of the coating layer surface in the present invention is preferably 10 ⁹ to 10 ¹³ Ω / □. When the electric resistance value exceeds 10 ¹³ Ω / □, there is a problem in transportability in the printing process.

In the present invention, the adhesion of the coating layer, solvent resistance,
In order to further improve the heat resistance, it is preferable that the coating layer contains a cross-linking agent.

The term "crosslinking agent" as used in the present invention means a coating having a three-dimensional network structure by a crosslinking reaction with a functional group present in the resin component, such as a hydroxyl group, a carboxyl group, a glycidyl group or an amide group. Typical examples of the cross-linking agent for forming the layer include methylol- or alkylol-based urea-based compounds, melamine-based compounds, epoxy compounds, isocyanate compounds, and aziridine compounds. In the present invention, it is preferable to use an isocyanate compound from the viewpoints of the adhesiveness to the film support and the crosslinkability among these.

These cross-linking agents may be used alone or in combination of two or more depending on the case. The addition amount of the cross-linking agent is selected depending on the type of the cross-linking agent, but is usually preferably 0.01 to 50 parts by weight, more preferably 0.1 to 30 parts by weight, based on 100 parts by weight of the solid content of the resin component. . Further, it is more preferable to use a crosslinking catalyst together with the crosslinking binder because crosslinking will proceed further. As the crosslinking catalyst, known ones such as salts, inorganic substances, organic substances, acid substances and alkaline substances can be used. The amount of the crosslinking catalyst added is 10 to 50 parts by weight, preferably 15 parts by weight, based on 100 parts by weight of the solid content of the crosslinking binder.
~ 30 parts by weight. The resin component to which the crosslinking agent is added is applied to the film support and then crosslinked by heating, ultraviolet rays, electron beams or the like, but the method of heating is generally used.

The center line average roughness Ra of the coating layer constituting the offset printing sheet of the present invention is 0.50 to 1.30 μm.
It is preferably m. More preferably 0.70
It is 1.15 μm. When Ra is smaller than the range of the present invention, ink set-off occurs when the printed matter is stacked in the printing step, which is not preferable. On the other hand, when the amount is larger than the range of the present invention, the ink transfer property is deteriorated and the printed matter becomes light, which is not preferable.

Further, the thickness of the coating layer constituting the sheet for offset printing of the present invention is not particularly limited, but is preferably 0.5 μm to 50 μm, more preferably 1.0 μm to 20 μm. Is desirable in terms of uniform coating property and adhesiveness of the coating layer. Further, in the coating layer, if necessary, within a range that does not impair the characteristics of the present invention, known additives, for example, coatability improver, thickener, antioxidant,
An ultraviolet absorber and a dye may be contained.

The method of providing the coating layer in the present invention is such that a film support which is a base material is stretched in advance in a film forming step, then a liquid adjusted to a predetermined amount is applied, and then dried. A method of providing a coating-drying step after winding the material film as a single film is preferably applied.

The coating method is not particularly limited, but gravure coating method, reverse coating method, reverse gravure coating method, kiss coating method, die coating method, metalling bar coating method, etc. are possible because high speed thin film coating is possible. Known methods can be applied. The coating speed,
The coating film drying conditions are not particularly limited, but it is desirable that the coating film drying conditions be performed within a range that does not adversely affect various properties of the coating layer and the support.

[0034]

EXAMPLES First, a method of evaluating various characteristics according to the present invention will be described.

(1) Smoothness Oken type smoothness tester (model KB-15) manufactured by Asahi Seiko Co., Ltd.
It was measured at. The average is shown as n = 5.

(2) Adhesiveness of coating layer The adhesiveness of the coating layer / support is such that a crosscut (100 pieces / cm ² ) is put on the coating layer, and a cellophane tape: CT- is placed at 45 ° to the crosscut surface. 24 (manufactured by Nichiban Co., Ltd.)
Was adhered and pressed back and forth 10 times with a load of about 5 kg using a hand roller, the cellophane tape was forcibly peeled in the direction of 180 °, and the degree of peeling of the coating layer was observed and evaluated. Judgment criteria are ◎: very good (no peeling), ○: good (peeling area less than 5%), Δ: somewhat inferior (peeling area 5% or more and less than 10%), x: poor (peeling area 20% or more). And

(3) Coating layer thickness It was determined by measuring with a micrometer or a dial gauge.

(4) Ink setting property A printability tester RI-2 type (manufactured by Akira Seisakusho Co., Ltd.) was set with 4-division rolls having a diameter of 6.5 cm and a width of 4.7 cm, and an oil-based offset was applied to each roll. Printing ink "TK Mark Five New" (manufactured by Toyo Ink Co., Ltd.)
Was coated with 0.3 cc with an ink pipettor and solid printing was performed. Then, measure the time until the printed surface is overlaid with the coated surface of OK coated paper (Oji Paper Co., Ltd.), and a metal roll with a linear pressure of 353 g / cm is run to prevent transfer to the OK coated paper. Then, the judgment was made according to the following judgment criteria. ◎: Less than 20 minutes ○: 20 to 45 minutes △: 45 to 60 minutes ×: 60 minutes or more

(5) Ink transfer property Printing was carried out in the same manner as the ink setting property measurement, and the optical density (reflection) of the printed surface was measured by Macbeth Densitometer T manufactured by Macbeth.
It was measured by R-927. The criteria for judgment are: ⊚: 2.4 or more ∘: 2.2 or more and less than 2.4 Δ: 2.0 or more and less than 2.2 x: less than 2.0

(6) Ink drying property Printing was carried out in the same manner as in the measurement of ink setting property, the coated surface of the OK coated paper was superposed on the printed surface, and the printed surface was left standing for 24 hours, and the printed surface was clawed. It was evaluated by rubbing lightly. Criteria were as follows: ◯: no peeling, Δ: peeling after repeated rubbing, ×: easy peeling.

(7) Suitability for stacking printing rods Printing was carried out in the same manner as the measurement of the ink setting property, the printed matter was cut into 0.05 × 0.05 (m ² ), and several sheets were piled up and loaded from above. (90 g) was applied and left for 2 days, and the state of set-off was observed. The criteria for evaluation are: ◯: no set-off Δ: slightly set-off X: set-set large

(8) Blocking resistance: Ten measurement samples of 5 cm × 5 cm were stacked, and a load of 1 kg was applied on top of them, and a constant temperature and humidity oven (40 ° C., 90 ° C.) was used.
% RH), the sample for measurement was lightly peeled off by hand for 24 hours, and judged according to the following judgment criteria. 1: Peel off without doing anything 2: Peel when shaken lightly 3: Peel when a little force is applied 4: Peel with sound 5: Completely adhere

(9) Surface electric resistance value: Measured with a digital ultra-high resistance, micro ammeter (model R8340) manufactured by ADVANTEST.

(10) Center Line Average Roughness According to JIS B0601-1967, the cutoff O.D. Center line average roughness Ra at 25 mm and measurement length of 4 mm
(Μm) was determined.

(11) Oil Absorption of Porous Particles The oil absorption was measured according to JIS-K-5101 to obtain the oil absorption (ml / 100 g) corresponding to 100 g of particles.

(12) Average Particle Diameter of Porous Particles The median diameter (μm) was determined by the Cole counter method.

Example 1 A polyethylene terephthalate homopolymer chip manufactured by a conventional method (intrinsic viscosity: 0.62, melting point: 259)
C.) was used to obtain a 75 μm biaxially stretched polyester film by a conventional method. On the polyester film thus obtained, a coating composition having the following composition was applied by a gravure coater.

The blending amount described below is a solid content weight ratio unless otherwise specified.

[Coating composition] 38 parts by weight of toluene, 10.5 parts by weight of isobutanol, 7 parts by weight of 2-hydroxyethyl methacrylate, and 10 parts by weight of n-butyl methacrylate were placed in a flask equipped with a condenser, a thermometer, and a stirrer. Department,
Acrylamide 1 part by weight, methyl methacrylate 28 parts by weight, acrylic acid 0.3 part by weight, azo hisisobutyronitrile O. 5 parts by weight were charged and the stirring polymerization was completed at 80 ° C. for 2 hours to obtain a poly (meth) acrylic acid ester copolymer.

Poly (meth) obtained by the above method
Acrylic ester copolymer 70 parts by weight, cationic acrylic polymer "Elecond" PQ-50B (manufactured by Soken Chemical Industry Co., Ltd.) 30 parts by weight, isocyanate compound "Sumijour" N-75 (manufactured by Sumitomo Bayer Urethane Co., Ltd.) Two
0 parts by weight and porous silica "Fineseal" X-37 (B) (Tokuyama Soda Co., Ltd.) as oil-absorbing porous particles (A)
Made, oil absorption 260ml / 100g, average particle diameter 3.7μ
m) 30 parts by weight, and porous silica “FINESEAL” T-32 (S) as an oil-absorbing porous particle (B) (manufactured by Tokuyama Soda Co., Ltd., oil absorption 270-320 ml / 100 g, average particle diameter 1. 0 μm) 30 parts by weight was diluted to 30% with a toluene / methyl ethyl ketone mixed solvent (1/1) to obtain a coating material.

The offset printing sheet thus obtained had excellent ink setting properties, ink drying properties and blocking resistance as shown in Table 1.

Comparative Example 1 An offset printing sheet was obtained by applying a coating material having a composition of 25 parts by weight of n-butyl methacrylate resin and 75 parts by weight of toluene onto the polyester film of Example 1 by means of a metering bar coater. .

As shown in Table 1, the thus obtained offset printing sheet had insufficient ink setting property, ink drying property and blocking resistance.

Comparative Example 2 An offset printing sheet was obtained by the same method except that the oil-absorbing porous particles (B) were used in the coating material of Example 1.

As shown in Table 1, the thus obtained sheet for offset printing had poor ink transfer properties, and also had poor ink setting properties and ink drying properties.

Comparative Example 3 An offset printing sheet was obtained by the same method except that the oil-absorbing porous particles (A) were used in the coating material of Example 1.

As shown in Table 1, the offset printing sheet thus obtained had set-off, ink setting property, and
The ink dryness was poor.

Example 2 An offset printing sheet was obtained by the same method except that 20 parts by weight of titanium oxide: CR-50 (manufactured by Ishihara Sangyo Co., Ltd.) was added to the coating material of Example 1.

The offset printing sheet thus obtained was, as shown in Table 1, excellent in ink setting property, ink drying property and blocking resistance.

[0060]

[Table 1]

[0061]

INDUSTRIAL APPLICABILITY The offset printing sheet of the present invention can use an ordinary oil-based offset ink for paper,
It does not cause ink set-off during the offset printing process, and has excellent ink transfer properties, ink setting properties, ink drying properties, antistatic properties, and blocking resistance.

The offset printing sheet obtained as described above can be preferably used not only for offset printing but also for various printing sheets and sheets for electric signboards.

Claims (5)

[Claims] 1. An offset printing sheet comprising a coating layer containing a resin component and oil-absorbing porous particles on at least one side of a plastic film, wherein the oil-absorbing porous particles have an average particle diameter of 2.0. ˜18.0 μm oil-absorbing porous particles (A) and average particle size 0.3 to 4.0 μm
A sheet for offset printing, which is a mixed particle of the oil-absorbing porous particles (B). 2. The offset printing according to claim 1, wherein the resin component is a reactive monomer-containing poly (meth) acrylic acid ester copolymer and a quaternary ammonium salt-containing cationic acrylic polymer. Sheet. 3. The offset printing sheet according to claim 1, wherein the coating layer contains a hiding white pigment. 4. The sheet for offset printing according to claim 2, wherein the coating layer is crosslinked with an isocyanate compound. 5. The center line average roughness of the coating layer is 0.50 to
The offset printing sheet according to claim 1, wherein the offset printing sheet has a thickness of 1.30 μm.