DE1497129A1 - Anti-corrosive primer suitable for electrostatic imaging - Google Patents

Description

III / K FRANKFÜRT (MAIK), June 18 ^ 1965

Dai-Nippon Toryo Kabushiki Kaisha,

No »J8, Nishino Shimono-choj Konohana-ku, Ohsaka-shij Japan»

Anti-corrosive primer suitable for electrostatic imaging »

The invention relates to a paint for priming (primer) _t both the corrosion protection is as well as or in the way of electrostatic photography "xerography

Records on metallic documents permitted

I ¹ Ur die ^; For the preparation and further processing of metal parts for welding and cutting, it is known to apply markings and drawings to these metal parts using the xerographic process. For this purpose, an insulating resin, a powdered photoconductor and, if necessary, a crude agent are dispersed in a volatile solvent and the metal surface is coated with this. Then it is dried quickly »B» in cascade ·· or liquid process «

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A coating for this purpose must meet the following requirements meet: You must immediately after, the corona discharge high potential, hereinafter referred to as "initial potential", have »The decrease in the electrostatic charge potential in the dark, hereinafter referred to as" dark loss "., must be slight be. üif the surface before the corona discharge is exposed to light is (pre-exposure), the initial potential should thereby be or the loss of darkness or the ability to regenerate are not adversely affected »By a small amount of light radiation if a strong drop in potential is to be achieved (sensitivity)

In addition to these elektrofotogfafischen properties, it is desirable that the coating also acts as a corrosion inhibiting G-rundierung "S ¹ Ur the primers used in shipyards must meet the following requirements: good adhesion, fast drying, ^ uter corrosion protection, good light resistance, good adhesion for more Coatings »good weldability of the base,

Use the 3 layers known for xerographic corners "Vinyl resins, z" £ "vinyl chloride-vinyl acetate Jopol ^ merisate or vinyl acetate resins, acrylic resins, e.g. 3, ketfeacrylharze, silicone resins or mixtures of these resins »Many of the known coatings are adversely affected by pre-exposure, and the loss of darkness during 6 minutes is too great »This period of time but it is, for example, in shipbuilding, where this process is often used, unavoidable.

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U97129

that with vinyl resin, polyester resin, etc. polymerized or -mixed is · With such coatings' they could Requirements regarding photo sensitivity are met « However, they are unsatisfactory with regard to corrosion protection, |

"i

Adhesion on metal surfaces, compatibility with the other paints and the weldability of the metals. In practice, the procedure was that after the whitening or cutting, the film was scraped off and then the corrosion protection primer was applied, or you had to use g

choose a special topcoat with a very limited selection. Both are very annoying and unsatisfactory, especially in shipbuilding *

The coating according to the invention fulfills the requirements the yerographic sensitivity and at the same time that of a primer coat with corrosion protection effect according to the invention an epoxy resin hardened with isocyanate (-NGO) is used together with a photoconductor *

It is known that I used for epoxy resin coatings

One-pot or two-head systems · The former are found oil-modified epoxy esters and high molecular weight epoxy resins · Bei the latter are amines, polyamides and acid anhydrides for Hardening used. These \ were not previously made for photosensitive Coatings used because they lead to a low initial potential or very high dark loss · However, achieved ' with the epoxy urethane resins used according to the invention better! otoenipfindlichkeit than with the mostly used

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to lead·

the silicone vinyl acetate coatings, and they also have all the properties that ffb? a corrosion sohutati] 3? ifun "g. ^ m '/ ■ were required.

The most varied of substances or compounds known for this purpose can be used as photoconductors · To be preferred are zinc oxide and selenium photoconductors, as they provide the best results for xerography and corrosion protection at the same time

According to the present invention, the epoxy urethaxy resin has a molecular weight from preferably about 500 to 4-οοσ (viscometric Other molecular weight epoxy resins are for

U.N
Corrosion protection primers / appropriate * Preferred are

Such urethane _r which the Isocyanatgrirpjierung as end group, and are capable of undergoing a substantially equivalent response to the GH groups of the epoxy resin * ^ ''

Isocyanates which are typical for the purposes of the invention are: 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphynylmethane-4-, ^{4--1 -diisocyanate, diphenylmethane-4, 1-} diisocyanate, triphenylmethane-4-, 4 ¹ , 4 "-triisocyanate, hexamethylene diisocyanate,

OOOHH (OH

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NOO

000]

GH _x CBEUO; CH _o 0G0HH

OCOHH - * -

HOO

As epoxy resins, for example, the following can be used: -;

Molecular epicote Jm 834 (average / weight 47o), Bpikote Φ 1oo1 ■ '

(average MG «, 9oo), Epikote Φ 1οο4 · (average—

liches MG 14oo), Epikote Φ · 1oo7 (average M.G0.29oo), | Epikote φ 1oo9 (average MG, 375o) eto »(manufacturer Shell Chemical Corp»)

The weight ratio of epoxy resin to isocyanate "or resin containing isocyanate groups is 3o-95 · 7o-5 ·.

In the examples which follow to further illustrate the invention all quantities are given in parts by weight *

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Examples

Liquid A Bäüipiel 1 Example 2 Epoxy resin * -1 2o parts 5o parts Zinc oxide 1oo " 1oo " Methyl ethyl ketone 2o » 2o » Methyl isobutyl ketone 3o- " 3o y Xylene 100 ^m 82 ^d Liquid B Isocyanate resin * -2 4o "axes 28 parts

dissolved in butyl acetate

* -1 »epoxy resin with molecular weight 29oo

(Epikote Φ 1oo7 from Shell Chemical Corp.)

* -2 m isocyanate resin (Desmodur L from Bayer AG)

, Was used for Liquid A if erfolderlieh, a Farbsensi- "bilisator, z ^ B. Rosefeengal or fluorescein _t added, then the mixture was in a usual manner, zBin a colloid mill _s dispersed · He liquid B is mixed only prior to application of the coating *

To produce the test pieces, panels made of 10 mm thick steel (shot blasted steel) with a dry film thickness were used from 3o to 6o ΐημ coated and in a hot air oven during Dried for 2 minutes at 23o °. The panels were pre-exposed to a light source of 500 lux for 2 hours and then kept in the dark for 20 minutes * It was then charged with corona discharge | to the loss of licks Determine · 6 minutes later, an original drawing was made on

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The charged surface of the layer is projected in order to generate the latent electrostatic image there »Development was carried out according to customary methods, e.g. using a liquid« The test pieces were cut along the outlines of the developed image with ooar epoxy paint),. \ Corrosion protection etc · tested «For comparison, known photosensitive layers were tested in the same way«
The results are shown in Table 1

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Known coatings Vinyl- Silicon- Epoxy ·· chloride vinyl · · hprz
Vinyl ac et at (aminsuSetat · , ..>. Belonged ^ (3) " ^C4) (5)

Coating
invention after ! formal
Corrosive example 1 Example 2 protective ground » Would be empir <> r <lernif! primer

At first-
potential
Vo. (-V) 3oo 3oo 175 I00 / I00 800 800 O Dark - »^
loss "* O 40 O 75 15th O Pre-exposure
tion bad Well bad out
draws out
draws bad Sensitive
speed (Lux
sec) under
3oo under
3oo I000 under under
3oo Drying
Peeling off
at the stretch
rolling Well
no bad bad.
part, far
going wisely out
draws
no out
draws
no Well
no Liability on
steel plate 50 / I00 0/100 100/100 100/100 I00 / I00

Saturation potential over 3oo (·

clear picture should be close at 6 DunkelverltLsi; develops «earth

Resistance to irradiation for several hours with 5,000 Ti ^ yy

(Recovery time 2o min)

less than 3oo lux sec
(Light source: 3o-6o Lux)

2 min at 23o ^e C

SoXl 5 ¹¹¹ U "after! Drying when rolling, does not flake off

After the cross cutting test (backlog / 1οo)

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Known Coatings Vinyl - silicone - spoxychloride - vinyl - resin - vinyl acetate (amine - acetate - _r ,, \ hardens) (31 ⁽⁴⁾ (5) L

Coating according to the invention

Example 1 Example 2

Normal corfosion protection

Yiash
primer

Required orders

Loading
availability iait
further to
stroked bad bad bad out
draws out
draws Well Visual white
availability Well bad Well out
draws out
draws Well behavior
home gas ■
Cut Well Well Well out
draws out
draws Well Corrosion
resistant
speed partially
rusted partially
; rusted ι none
Corro
sion no
corrosion no
corrosion no
corrosion Kurice Mr
the
drawing 3 4- 5 1 MM

* —1 The silicone resin makes the welding resistance inadequate
* -2. ! For the cross cut it was made of polished steel blades
* - »3 The decline in the dark is V6 min./Vo χ 1oo

good coatability for all sniffing paints (especially coal epoxy -

3? Colors)

according to different
exams

Should be easy to process.

Storage in bakeries door more than 1 month

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-1ο-

The attached diagram shows the curves for the decrease in the electrostatic potential dashed curves, for the non-preexposed test pieces the full curves "For the preexposure," was irradiated for 2 hours with a light source of 50,000 lux and then left for 20 minutes. Curves 1 and 2 relate to the coatings according to the invention of Examples and 2, the curves 3, 4 and 5 relate to the known coatings listed in the table The curves for the corresponding pre-exposed coatings are denoted by 1 ', 2 ¹ ^ 3', 4 ¹ and 5 ¹ .

For the test of the initial potential, the coating surface was used by means of corona discharge to the saturation potential charged

fc The determination of the dark loss was based on the initial saturation potential Vq and the potential after 6 minutes in dark loss V _fi , measured in volts

The pre-exposure took place for 2 hours with 5,000 lux »on, The test pieces then remained in a dark room for 20 minutes. Then the coating became a corona discharge again exposed and the saturation potential determined. This value

was with the saturation potential measured before the pre-exposure compared »If the difference was limited, the test piece was considered usable ·

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The wash primer listed in the table is a trade · « product | that the tap on. National Railways Standard JRS-13o67 " 13AR3 corresponds to »». . . .

The known coatings 3t 4 listed in the table and 5 were made from the following mixtures:

3) Vinyl Chloride Vinylaeefcat Coating

Zinc oxide

Vinylohlorid-Vlnylaoet at-Oopo lymer 40% butyl acetate solution MIBK (Methylieobufcylketon ^ Xylene

4) Silicone vinyl acetate coating

Zinc oxide

Silicone resin KR-211 (Shin-Etsu Chemical) 7o% töluol solution

Vinylacet atcopolymerisat 5o% ige Aethylacetatlösung xylene
Ethyl acetate

5) Epoxy resin coating

Jl * zinc oxide

Epoxy resin (Epikote # "1oo1, Shell Chemical Corp") butanol
Xylene

B «40% butanol-xylene solution of the Amine adduct epicure hardener

Liquids A and B were mixed shortly before coating

1oo Ropes 95 H 25th ti 7o H 1oo Parts 25th 3o . M. 8o ti 2o U 1oo Parts 35 It 7o Il 5o H 7.5 Parts

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Claims (3)

Claims Gxmndierung, which at the same time sum corrosion protection and for Generation of electrophotographic! "· Images is used, characterized in that that they are made using epoxy resins and isocyanates or ' Resins containing isocyanate groups are produced as hardeners and contains a zinc oxide or selenium photoconductor « 2) reason ierunf; according to claim 1, characterized in that the weight ratio of epoxy resin to isocyanate compound or "isocyanate is in the limit of jk> -95 ^: 7o-5" 3) primer according to claim 1 or 2, characterized; through the Use of epoxy resins whose viscosity is determined Molelailarge was between about 500 and 4,000 909821/0898