JPS59159863A - Composition for printing ink - Google Patents

Abstract

PURPOSE:To provide the titled compsn. which has good dispersibility and dispersion stability and can produce ink for use in offset printing, which does not cause offset, by incorporating a specified low-molecular fluororesin copolymer in a vehicle. CONSTITUTION:A modified low-molecular polytetrafluoroethylene copolymer having a number-average MW of 1,000-50,000 and a particle size of 0.1-50mu and composed of 60-99.999mol% of tetrafluoroethylene and 40-0.001mol% of other fluorine-contg. alpha-olefin such as hexafluoropropylene, is used. No more than 20pts.wt. said modified polytetrafluoroethylene is blended with 100pts.wt. vehicle such as rosin-modified phenolic resin or polyamide resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition for printing ink, and more particularly to a composition for offset printing ink.

In offset printing, the ink that is placed on an original plate made of metal or resin is not transferred directly to the paper, but is first transferred to a rubber blanket (a rubber blanket is wrapped around the rubber cylinder of the printing machine), and then retransferred onto the paper. This is a printing method that uses the elasticity of rubber to transfer ink, compared to methods that print directly from a hard metal plate, so even if the surface of the paper is rough, it can be printed with less printing pressure, resulting in beautiful results. Its feature is that it produces a printing effect.

However, as mentioned above, offset printing has the disadvantage that the ink film is thin because the ink is retransferred through a rubber blanket, and to compensate for this disadvantage, the ink composition contains a colorant with high tinting power. Contains a large amount.

As a result, when printed materials are stacked after printing, smearing due to colorants with high coloring power is likely to occur, and prevention of this smearing is one of the challenges in offset printing.

Therefore, various preventive measures have been investigated, and it has been found that it is effective to add a small amount of low molecular weight polytetrafluoroethylene (hereinafter referred to as low molecular weight PTFE) powder to the ink composition and disperse it well. . but,
Ink compositions coated with low-molecular-weight PTFE powder have poor dispersibility and dispersion stability of the low-molecular-weight PTFE, which causes aggregation and sedimentation of the PTFE in the ink reservoir (raUk molecules). However, the intended purpose could not be fully achieved.

Therefore, the present inventors further investigated dispersibility and dispersion stability14:
As a result of extensive research into good additives, it was discovered that a small amount of a specific low molecular weight fluororesin copolymer is effective in preventing backing, and has good dispersibility and dispersion stability, and the present invention has been made. I have come to complete this.

That is, the present study aims to provide a printing ink composition comprising a modified low molecular weight polytetrafluoroethylene mixed and dispersed in a vehicle.

The vehicle used in the present invention is the vehicle used in printing 1, such as rosin-modified phenol 6? JIIR
, M phenol resin, rosin ester resin, Ronne modified maleic acid resin, mineralized rosin, styrenated resin, rosin modified resin, fatty acid modified alkyd resin, polyamide resin, xylene grip 11 effect They are used alone or in combination of two or more.

The modified low molecules used in the present invention are
．． 999-r= refers to a copolymer with 0.001 to 40 mol% of fluorine-containing 9g U-A'V fins, and the fluorine-containing α-olefin provided by copolymerization is expressed by the general formula : % formula % (wherein R is chlorine, a C-fluoro or polyfluoroalkyl group having 1 to 10 carbon atoms, or carbon.

), which is used by adding and mixing at a ratio of 20 parts by weight or less to 11 parts by weight per 100 parts by weight of the vehicle.

This paternal low molecular weight 11-topolytetrafluoroethylene is
It can be formed by polymerization using a chain transfer agent or by decomposing a polymeric female tetrafluoroethylene using an electron beam, heat, etc., and the diameter is usually 0.1 to 50 p.
The m number average molecule 8+1 is 1,000 to 50.0 (10. The copolymerization ratio of this fluorine-containing α-olefin is -1
=, (c! range is preferred. If it is smaller than the above range, the dispersibility and dispersion stability will be poor, and if it is larger than the above range, the non-adhesive property will be decreased and backing will easily occur.

The printing ink flJ composition of the present invention consists of the above-mentioned vehicle and modified low molecular weight ↑j) polytetrafluoroethylene, but this composition is further supplemented with colorants, solvents and other substances according to a conventional method. By adding auxiliary agents and other fluorine-based additives as necessary, it can be made into an ink for offset printing. It can also be used as an ink for other printing applications (for example letterpress or intaglio) with different compositions if desired.

Next, the present invention will be specifically explained with reference to Examples, Comparative Examples, and Reference Examples.

'*Example polyamide resin (viscosity 100CP, specific gravity 0.9.25°
C) 959 (fc modified low molecular weight fj% polytetrafluoroethylene (tetrafluoroethylene 99.78 mole%, hexafluoropropylene 0.22 mole/I/%
copolymer, number average molecular weight 5,000 to 10,000
, particle size 02-0°4 μm) was added and mixed well using a turbo disperser. This mixture was used as a sample to measure the following FM generation depth (dispersibility) and sedimentation degree (dispersion stability).

Trace generation depth and dispersion) (, IIS K 510
1. Pour the entire groove into the deepest part of the kettle, holding the top of the scraper near both ends, and pour the miso into the corner (1st step).
Place the blade at the deep end of the miso in a 7-slice motion, and pull it toward the shallow end of the miso at a constant speed. 10 after drawing
Within seconds, with -F of the diffused illumination, look at the trace from due north in the direction of 111 angle to the short side of the grindmeter, and mark the scale where three or more lines start to appear (depth of trace occurrence, 1 inch).
) was recorded. This operation was repeated five times and the average value was determined.

The smaller the (Ii") of this trace (depth of trace occurrence μm), the better the dispersibility (i.e., the additive is not aggregated).
Indicates natoto.

(,-, Kleindometer Tokeshiki 11), length 200-250 mm, width 100-1
50mm.

It is made of a hard special alloy with a thickness of 15 to 254 m, and on one smooth surface there are 120 to 160 mm in length and 15 to 2 mm in width.
5mm.

It has an extremely thin wedge shape that is continuously sloped from a depth of 25 μm or 125 μm (with one or two grooves).
There are books. The scale next to the miso is the depth at that position, expressed in micrometres.

The scraper is as shown in Figure 2, and has a length of 90~
100 mm, width 40-60 mm, height 5-10 m
It is made of the same alloy as the Klein meter, and the cutting edge is exactly in a straight line, but the cutting edge C is rounded to a diameter of 25 μm.

The measurement results are shown in Table 1.

Sedimentation degree (dispersion stability) Immediately after mixing 25+++t of the mI mixture, 14
II・mlX 16Q +nm test 1 test $■ The sample was sealed and allowed to stand upright at 25"C for 72 hours, and the degree of sedimentation of the additive was measured.

The degree of sedimentation (A) here is the value obtained by dividing the length from the bottom of the test tube to the liquid surface (4) by the length (B) from the liquid surface to the top of the sedimented additive. It refers to the value multiplied by 100 and is expressed by the formula: %. A small value of the degree of sedimentation (%) indicates that the additive has good dispersion stability due to sedimentation and separation.

The results are shown in Table 1 along with the depth of occurrence of scratches in μm.

Examples 2 to 4 Using the modified low molecular weight polytetrafluoroethylene shown in Table 1, mixing and measurements were carried out in the same manner as in Example 1 except for the following.

The measurement results are shown in Table 1.

Comparative Examples 1 to 2 The low molecular weight polytetrafluoroethylene shown in Table 1 was modified to
Mixing and measurement were carried out in the same manner as in Example 1, except that low-minute flat polytetraph 7 was used in place of rheoloethylene.

The measurement results are shown in Table 1 together with Examples 1 to 4.

Reference Example 40 parts by weight of each printing ink composition prepared in Comparative Example 1 and Example 1, 20 parts by weight of cyanine blue, 9 parts by weight of Victoria Blue Lake, 20 parts by weight of Gloss White, 10 parts by weight of Silicone Face, and boric acid. Lead 0.5
Parts by weight were added and kneaded using a roll mill at 90°C for 2 hours to obtain a printing ink. The ink prepared from the composition of Comparative Example 1 had a flow value of 18, a tank value of 9.0, and a critical surface tension of 20 dynes/tack; the ink prepared from the composition of Example 1 had a flow value of 18, a tack value of The value was 9.5, and the critical surface tension was 21 dynes/an.

Using both of these printing inks, perform offset printing Jiiif on 1000 sheets of art paper each according to the usual method,
It was left to overlap for 12 hours. When examining the back transfer after the lapse of this time, the printing ink prepared from the composition of Example 1 showed good results with no back transfer, but the printing ink prepared from the composition of Comparative Example 1 showed back transfer in some places. This occurred, and there was no sufficient effect to prevent the back from rolling.

[Brief explanation of the drawing]

Figure 1 shows the grind meter. Figure 2 shows scrapers (2 types) An example was shown. Below

Claims (1)

[Claims] 1. A printing ink composition comprising a vehicle mixed with and dispersed with modified low molecular weight polytetrafluoroethylene. 2. For the printing ink of the first stack, wherein the modified low molecular weight polytetrafluoroethylene is a copolymer of 60 to 99.999 mol% of tetrafluoroethylene and 40 to 40 mol% of fluorine-containing α-olefin o, ooi. Composition.