JPH0441799A - Coating composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a coating composition for press processing, particularly,
The present invention relates to a coating composition for press processing that is coated on the surface of printed paperboard.

[Conventional technology]

Conventionally, in order to improve the gloss, abrasion resistance, water resistance, etc. of printed paperboard, the paperboard surface was coated with a coating agent using a roll coater or gravure coater, and then pressed to make the coating surface mirror-like. Surface treatment methods are generally known. Such surface processing is generally performed using a pair of clamping belt type apparatus as shown in FIG. As shown in the figure, the device is equipped with a pair of opposing belt bodies 110, 120, and the belt body 110 in the upper part of the figure includes a pair of rotating rolls 112, 114 and an endless metal roll wound around these. Similarly to the belt body 110, the belt body 120 at the bottom of the drawing also includes a set of rotating rolls 122,
124 and an endless metal belt 127.

The holding rolls 112 and 122 at the tip end (right side in the drawing) of such an apparatus are equipped with a heating mechanism such as steam (not shown), and can heat and pressurize the coating agent on the surface of paperboard or the like. This clamping roll 112
After passing through the belts 117, 127 and 122, a cooling mechanism (not shown) is provided between the belts 117, 127 and the clamping rolls 114, 124 before the belts are discharged.
The peelability between the roller 114 and the coating agent at the position 14 and 124 is ensured.

In other words, the coating agent applied unevenly on the surface of the workpiece 200 such as paper is given smoothness by passing through this device, and the glossiness of the printed paperboard is improved, and the coating agent Along with physical properties, wear resistance,
Improves water resistance, etc.

[Problem to be solved by the invention]

However, in the method of the above-mentioned apparatus, after the coating agent is heated under pressure using a rotating roll and an endless belt, the coating agent must be cooled until it is discharged so that it can be easily peeled off from the belt. Must be. In order to achieve sufficient cooling, it is not possible to increase the rotational speed of the belt, that is, the processing speed, and it is not possible to use a device consisting only of a pair of heated rolls, resulting in the problem that productivity cannot be improved. was.

In view of these circumstances, an object of the present invention is to provide a coating composition that can obtain gloss by so-called press processing and that can be easily peeled off from a hot roll at a high temperature without cooling.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a coating composition for press processing that is applied to the surface of a workpiece, comprising:
The coating composition has a glass transition temperature of 70 to 11
0°C acrylic resin and a phosphate ester surfactant represented by the following general formula (wherein R1 represents an alkyl group or an alkylphenyl group, and n is 1 to
50, R2 represents hydrogen, oxyethylenealkyl or oxyethylenealkylphenyl).

Examples of objects to be processed in the present invention include printable plate-like objects and roll-like objects, such as book covers, calendar paper, cardboard, cartons, and bags.

The coating composition of the present invention as shown below is applied to the surface of the workpiece.

That is, the coating composition of the present invention contains an acrylic resin, and this acrylic resin is limited to those having physical properties having a glass transition temperature (hereinafter simply referred to as Tg) of 70 to 110°C. This is because if the Tg value is less than 70°C, it becomes difficult to perform high-temperature peeling, which is the objective of the present invention.On the other hand, the reason why the upper limit of Tg was set at 110°C is that this value is generally the upper limit of acrylic resin. This is because it is something that is determined by itself.

As such acrylic resin, acrylic acid alkyl ester (CH2=CHCOOR') or methacrylic acid alkyl ester (CH2=CH3COOR')
The following polymeric resins are mentioned, in which R' represents an alkyl group such as methyl, ethyl, n-butyl, l-butyl, t-butyl, 2-ethylhexyl, lauryl, or the like. Also, one or a mixture of two or more of these various acrylic acid alkyl esters and methacrylic acid alkyl esters and copolymers of styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, vinyl acetate, and vinyl chloride-vinyl acetate. Can be used as acrylic resin.

Acrylic resins such as No. 2 have a smooth surface when pressed, have good gloss releasability, and have good adhesion to both water-based and solvent-based gravure inks as underprint inks.

Furthermore, the coating composition of the present invention has the following general formula [
Contains a phosphate ester surfactant represented by 1.

General formula [1] In the above general formula [1], R1 represents an alkyl group or an alkylphenyl group, and the alkyl group has 1 to 3 carbon atoms.
0, more preferably 12-15.

n is the number of moles of ethylene oxide added, and the value of n is an integer of 1 to 50, more preferably 3.

R2 is hydrogen, oxyethylene alkyl (R.

(CHCH20) n ) or represents oxyethylenealkylphenyl. Note that R1 and n have the same meanings as in the above case.

The phosphate ester surfactant represented by the general formula [1] is contained in an amount of 2.5 to 10 parts by weight based on 100 parts by weight of the acrylic resin.

When this value is less than 2.5 parts by weight, the high temperature releasability becomes poor, and when this value exceeds 10 parts by weight, the smoothness of the coating film surface after pressing becomes poor. Such surfactants mainly function as mold release agents, have good high-temperature releasability, impart lubricity to the surface of press coatings, and are also effective in improving wear resistance and scratch resistance.

The acrylic resins and surfactants mentioned above are of the type that can be dissolved in organic solvents, and the organic solvents used include aromatics such as toluene, esters such as ethyl acetate, ketones such as methyl ethyl ketone, and isopropyl. One or more alcohol-based solvents such as alcohol can be used.

Furthermore, the coating composition of the present invention further contains polyethylene wax, paraffin wax, microcrystalline wax, etc., which are usually used in printing inks, as an abrasion resistant agent, and a mixture of an acrylic resin and an organic solvent.
It is preferable to add in an amount of 5 parts by weight or less per 00 parts by weight.

If it exceeds 5 parts by weight, the coating film becomes cloudy and has poor gloss.

Furthermore, as a surface smoothness improver, vinyl chloride-vinyl acetate copolymer (degree of polymerization 100-400, vinyl chloride/vinyl acetate ratio 50-150)
80/20> is a mixture of acrylic resin and organic solvent 1
It may be added in an amount of 15 parts by weight or less per 00 parts by weight. If it exceeds 15 parts by weight, high temperature releasability will deteriorate.

Other mold release agents include lecithin, fatty acids such as stearic acid, fatty acid esters such as n-butyl stearate, fatty acid amides such as stearamide, and one or two surfactants of partial esters of fatty acids and polyhydric alcohols. More than one seed may be added.

The coating composition of the present invention can be applied to workpieces printed with either water-based ink or solvent-based ink without causing any problems.

〔Example〕

Hereinafter, the present invention will be explained in further detail by showing examples of the present invention.

Various compositions 1 to 11 shown in Table 1 below were prepared by appropriately combining and blending the types of resins, mold release agents, antiwear agents, and solvents shown below.

(Resin) r-1.n-butyl methacrylate (7g 50℃) r-2; Styrene acrylic resin (7g 92℃) r-3 Niacrylic-vinyl acetate copolymer resin (7864℃) r-4; Acrylic-vinyl acetate copolymerization Resin (T g 8
7℃) r-5; Vinyl chloride-vinyl acetate copolymer resin (degree of polymerization 1
00. Vinyl chloride vinyl acetate = 60 + 401 (mold release agent) m-1; In the phosphate ester surfactant represented by the above general formula [1], R1 is an alkyl group having 13 carbon atoms, n is 3, and R2 is Hydrogen surfactant m-2: In the phosphate ester surfactant represented by the above general formula [1], R1 is a phenyl group, n is 6, R
Surfactant m-3 in which 2 is hydrogen; In the phosphate ester surfactant represented by the above general formula [1], surfactant m-3 in which R1 is a nonylphenyl group, n is 4, and R2 is hydrogen; 4; A phosphate ester surfactant represented by the above general formula [1], in which R1 and R2 are nonylphenyl groups, and n is 7.

(Abrasion resistant agent) Polyethylene wax (solvent) S-1, toluene S-2; ethyl acetate S-3,1PA Various composition samples shown in Table 1 were mixed into so-called polysand, which is a paper/polyethylene/paper laminate. The original fabric was coated under the following press processing conditions.

That is, as a pre-process, a water-based acrylic ink is printed on a polysand raw fabric using a gravure printing machine, and then various composition samples shown in Table 1 are coated, and then 1.
Pressure 100kg/'c++f with hot roller at 20℃
A coating sample was prepared by press working at a speed of 10 m/min. Note that samples were similarly prepared in the case where the printing using the water-based acrylic type ink as a pre-process was changed to printing using a nitrated cotton/polyamide resin-based solvent ink.

The following evaluations were performed on these samples. The evaluation items and their evaluation criteria are as follows.

(glossy) The 60° reflectance was measured and expressed as a percentage.

(Releasability) The state of peeling when pressed with a hot roller at 120°C was examined. The evaluation criteria were as follows.

◎...There is no peeling sound, or if there is, it is very small.O...There is no abnormality on the coating surface, but there is a peeling sound.△...There is peeling, but there are cracks on the coating surface. Formed: Coating film removed by roller (Surface smoothness) The pressed surface was visually judged. The evaluation criteria were as follows.

◎...Extremely smooth surface O...Slightly uneven smoothness △...Things with uneven smoothness (adhesion to lower ink) For press-processed products, cellophane tape must be removed. The test was conducted.

The evaluation criteria were as follows.

O... The lower ink adheres to both water-based and solvent types △... The lower ink only adheres to either water-based or solvent types ×... The lower ink is water-based The results are shown in Table 2 below. Note that the sample numbers correspond to the composition numbers in Table 1.

Table 2 [Operations and Effects of the Invention] From the results in Tables 1 and 2 above, the effects of the present invention are clear.

That is, since the coating composition of the present invention contains a predetermined resin and a phosphate ester surfactant as a predetermined mold release agent, it not only provides gloss through so-called press processing, but also provides heat resistance. The coating composition can be easily peeled off from the roll while still in a high temperature state.

Therefore, unlike conventional methods, cooling for peeling is not required, and productivity is significantly improved.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a pair of clamping belt type press devices used for surface processing. 110.120...Belt body.

Claims (1)

[Scope of Claims] 1. A coating composition for press processing applied to the surface of a workpiece, the coating composition having a glass transition temperature of 70 to 11.
Acrylic resin at 0℃ and a phosphate ester surfactant represented by the following general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R_1
represents an alkyl group or an alkylphenyl group, and n is 1
an integer of ~50, R_2 represents hydrogen, oxyethylenealkyl or oxyethylenealkylphenyl). 2. The coating composition according to claim 1, wherein the phosphate ester surfactant is contained in an amount of 2.5 to 10 parts by weight based on 100 parts by weight of the acrylic resin.