DE1961220A1 - Pigments for making paper opaque - Google Patents

Description

American Oyanamid, Company, Wayne, New Jersey, V "St. A.

Pigments for making paper opaque

The invention relates to paper with improved opacity and gloss. It also concerns that Opacification of paper containing an optical brightener with zinc metatitanate.

Paper is currently made opaque with white pigments, of which rutile titanium dioxide, anatase titanium dioxide _{ or potassium hexatitanate are the most commonly used pigments. "Opacifying" is the reduction in the transmission of visible light to paper. The pigments mentioned are used in the pail of white paper because they reflect all visible light and do not discolour the paper. In άαη recent years has become esjüblich to introduce materials into the paper, the ale "optical brighteners" are known to dom paper to impart a high Weißßrad and high brightness. The action of these brighteners is generally based on the absorption of rather long-wave electromagnetic ultraviolet radiation, by means of which they pass from the ground state into a metastable state of higher energy. The energy release and return to the ground state takes place with the emission of radiation,

009828/1585 "._,

which are at least partly in the visible (blue.) area, des electromagnetic spectrum. ■

If rutile titanium dioxide, ariatastitanium dioxide or hexatitanate with or without brightener to opacify /. Paper used is the lightness of the paper ». as a result of absorption of electromagnetic radiation in the near ultraviolet region and visible region by the. , Opacifier limited. These opacifying agents reduce and promote the effect of the brighteners considerably an increase in the amount of brightener to make the desired Paper lightness is reached. There is therefore a need for white pigments for the opacification of paper, which Do not significantly impair the effect of the brighteners commonly used. "

The aim of the invention is therefore one which is suitable for opacification White pigment j the electromagnetic radiation of the visible range (wavelength 400 to 700 nanometers) or the near ultraviolet region is not substantially absorbed. Another object of the invention is to opaize Suitable white pigment which, when mixed with paper pulps containing a brightener, does not significantly reduce the effect of the brightener.

Surprisingly, it has now been found that zinc metatitanate pigment paper, which contains a brightener, effectively “makes it opaque and does not adsorb electromagnetic radiation in the visible region or in the n, ahesi ultraviolet to any significant extent.” It is very surprising “that zinc metatitanate a Such an effective pacifier is because rutil and anatase titanium dioxide, which are very similar in physical appearance and chemical activity to _3, absorb visible light to a considerable extent, while other white pigments such as potassium hexatitanate and andsra paper

009828/1685

INSPECTED

- 3 fillers that are poor opacifiers.

The zinc metatitanate used as an opacifying agent according to the invention preferably has a particle size distribution between about 0.05 and about 3 microns, the majority of which Part of the particles ranges from 0.2 to 0.5 microns. The methods of making zinc metatitanate pigment are known and the method used in each individual case is not critical for the purposes of the present invention as long as the pigment produced has a "color" and a particle size suitable for use as a means for opacifying paper.

The amount of zinc acetate titanate mixed with the paper depends on the desired degree of opacity. The amount used is less than that which causes chalking, and in the range of about 2 to about 20 weight percent, preferably about 7 to about 13 weight percent, based on the dry fiber weight.

The opacifying agent can be added to the paper in any known manner. Generally this will Opacifying agents in aqueous slurry with the paper stock mixed until a perfectly uniform mixture is obtained. J) Mixing can also be carried out in the presence of additional paper modifiers as they are normally used, e.g. paper binders, bleaches, Brighteners, filler pigments alum and resin glue.

Any brighteners that are generally recognized as effective brighteners for paper can be used for the purposes of the invention. Suitable paper brighteners include e.g. tetrasodium 4,4'-fcie H ^ "- (2-hydroxyethylamino) -6 - /" m (and p) -sulfanilinoJ7- ^s triaainr-2-yl7amino7-2 _f 2'-stilbene disulfonate, or disodium-4,4'-bin / ^- £ "4-anilino-6 - /"'bit (2-hydroxyethyl) aminoJ? ^r -striazili-2-yi7amine_o7-2,2'etilbenedi8sulfonate.

009821/1585

In the following examples, the white pigments are assessed on the basis of visual observation by three independent testers. Paper sheets with and without a brightener were examined and rated according to their brightness.

example 1

Sheets of paper were prepared using zinc metatitanate, lithium metatitanate, titanium pyrophosphate, potassium hexatitanate; and anatase titanium dioxide. The Zinkmetatitanat was a mixture of hydrous titanium dioxide and zinc oxide-containing water at 100O ⁰ C produced by Galzinieren .. The XRD pattern of this white powder was consistent for Zinkmetatitanat with the American Society for Testing Materials (ASTM). Lithiurametatitanat was made by calcining hydrous titanium dioxide and lithium hydroxide. 800 ^w C produced. The X-ray diffraction diagram for lithium metatitanate was in accordance with ASTM specifications for lithium metatitanate. Titanium pyrophosphate was prepared by calcining (750 ^ϋ 0) the white solid obtained after boiling hydrous titanium dioxide in dilute phosphoric acid. The hydrous titanium dioxide ,, which was used for the preparation of the products described above and for producing the _{Anatastitandioxids}} was generated according to the "sulphate process" in which a titaniferous material, eg ilmenite is digested with concentrated sulfuric acid to a product which is predominantly of titanium - and iron sulfate. The product cake is then dissolved in dilute acid and, after the titanium and iron content has been adjusted, subjected to controlled hydrolysis to precipitate water-containing titanium dioxide to remove impurities, which is filtered off and washed with the potassium hexatitanate used for these experiments. It is a commercially available pigment under the name TiFure PKT ^R. . '

Ί961220

To produce the paper sheets, the pigment and sodium rosinate were first added to a fiber suspension in the following way: paper stock and water were shoveled for 10 minutes using stirrers (15 cm χ 3.8 cm, (6 "χ 1 1/2") made of corrosion-resistant steel) at about 500 lipm. The amount of dry solids in the batch was adjusted to the desired weight by adding paper stock or water. In a 0.95 1 (T quart) Waring mixer operating at about 1000 rpm An aqueous pigment suspension was produced by sifting pigment into water. The Waring mixer was increased to 20,000 rpm and held for 5 minutes. After the slurry was added to the solids batch, the resulting mass was mixed for 5 minutes About 2.9 ml of a 4% aqueous sodium rosinate solution were added to the mass and mixed for about 5 minutes # ~ iger water-. riger aluminum sulfate solution adjusted to 5 »0. After adjusting the pH to 5.5 again with a 5 # aqueous sodium carbonate solution, the slurry was then passed through a laboratory sheet form (20 × 20 cm, 8 × θ ") with a sieve with a size of 0.25 mm ' If a brightener was used, 0.228 g of an 18% aqueous solution was added to the pulp suspension. The brightener used and tested was Ietranatri.um-4t4 ^l -bie / "^ i" - »( 2-hydroxyethylamino) ~ 6 ~ £ m £ and ρ) -aulf oani ^ ino ^ - 'i aminoJ7- ² i ² ' -etilbene-di-sulfonate. '

I. '' · Ι · ■. '■■■■ ..

j The handmade paper sheets have been through

with long-wave ultraviolet lipiit'ieit tintr wavelength /

ORtQtNAL INSPECTED

from 3000 to 4200 angstroms and rating the brightness of the irradiated paper checked by visual inspection. The results are shown in the following table guided. · ·

ORIGINAL INSPECTED

Tabel

O O (O

cn cn

2 ο

"Z. co

rn

Brightness test of pigmented, hand-scooped leaves with UV light pigmentation PKT • /Weight-^ \ ή * rate- \ • - r
Examiner 2 Test 3 < : ■ · pigment / Pigment \
j addition j
\ to Pa- /
\ pi er fabric / tion of \
added j
Pigments J Evaluation ("according to decreasing brightness ZnO, TiO ₂ ZnO-TiO ₂ Anatase 13th 25.3 4 weight% \ ability, arranged) TiP ₂ O ₇ TiP ₂ O ₇ ZnO.SiO ₂ 10 35.0 Pigment \
in the fer-]
Vtigen Pa- /
\ P ^ier / Examiner 1 Li ₂ O.TiO ₂ " Li ₂ O.TiO ₂ • 13th 25.8 3.29. ZnO.TiO ₂ 3.50 TiP ₂ O ₇ Anatase PKT CM "<
B. • 7th 46.5 3.35 Li ₂ O.TiO ₂ ⁶⁰ p
CVi / ->
ιτ \ a
I co
■ Ρ Q) U
* £ <£ ί Q) PKT Anatase • Η · Η 7th 48.0 3.26 PKT ο. «Α
6OH CD te
(D CM 3.36 Anatase • Η *
it ία I.
/

CD

- Paper weight-31 g / n ² σ- ! I. lbs ./ream)
brighter 1-3
H- S83 PS • L / ti 86Q0 , 2 ! j » Hd lbs' ./ ream) without
brighter H- H- On- H - (22.3 M. P.
ef Hd O B. S. ro
O ro IJ P. σ P. P. ί O ro with on- K3 it '
O K3 C + ο O B. CS CO • O H- H· • PapieEgewioht-52 "/ m ² P. Η3 ^ 3. -j Pl * PT Η3 -J ro O H3 (37 OJ H- H- H* ρ ro H- 13 ■ O O • ο O P.
e + ro ro ro ro P. 1-3 Previous year CQ Previous year Previous year - H Previous year H-
Hd ro O ro P. ro ro VJI ro UI 5 * CS ro ro .. ~ * O O VJV ro σ » "Oo "cn VYY "όο "co -j ro Previous year 00 Previous year Previous year VJl O Previous year ro 00 Yes -J Previous year ro Previous year O "Oo VO VJl -4 VJl O O Previous year ro tsi -J O Previous year Ir » CJ ⁴ Hd t » IT 00 Hd H- H> CJ * 'a ¹ P. O ro H P. M.
P. C + ro • O H9 ο O ro P. Tbsp P. O H- 1-3 VJl O CS pi Pl 03 • Hd H- {ft- ^ 3 1-3 -4 Pf t-3 ro O CS H- H· H- O ro P. O O O -4 Cf ro ro &. ro tsi P. H· a
H P. O co N ro σ
M. P. C + ro * O σ ro P. P. O 1-3 O CS Pi* ω • H- t-3 H3 -4 Pi ¹ (-3 O & H- H· H- ro P. O O O C + ro ro Hd ro P. σ * h3 Ana CQ CSl ro 3. ey H
P. cf. it
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P. CS P. O P ^ CO ro HS -4 Pf " O H- H- • O O . kB ro ro H- O ro

P σ-co H ¹ H CD

H cf Ο (S e +

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• CVJ CVJ P- - CVI EH co O O O O CD • rt • Η CVJ • Η 4 = EH EH EH CD W. * α • ti F '* i
ö d O O rrt CVJ ti CVJ VU • Η ,O CVl O EH CQ c— cvj PH CO O O M. O • Η CD ö . CVJ a a • rt • · —J in EH ο ι 1
■ £ 3 KS ti
N Eh KS Ph (B. OD CM VO UV O co CM CVJ / TH - Ti KS "d KS
r- Bi Cr al CM •H
EH O KS H
, α O
.-J O KS "™
6H in ■ σ » KS O kv CM C- O KS a IA KS C- Ä »ix IfS O
_ * - - CV EH kv OE)
te ΤΛβ3 4 » , JN CM s * JeT ^ BcI α O ί itljny A " ιπΒβα

As can be seen from the table, the paper that contains no pigment (labeled "blank" in the table) is the lightest paper of the papers without brighteners in ultraviolet light. The reason for this is that each of the pigments tested absorb visible light to a different extent. On the other hand, from the papers that. the brightener Tetranatriura-4,4 '/ ~ ^ - (2-hydroxyethylamine) -

"6'- £" m (uncl p) -sulfoanilino_y ~ s-triazin-2-ylJ7amin_7'- ² » ² ' ¹ -stilbene disulfonate, the paper that contains zinc metatitanate is the brightest, as the pigment from the light,' that is required to activate the brightener and / or is emitted by the brightener is least absorbed. ·.

Claims (4)

Claims . Method of making opaque. Paper, characterized in that there is a paper stock suspension Zinc metatitanate and a brightener are mixed in and paper is made from the mixture. 2. The method according to claim 1, characterized in that paper is produced that 2 to 20 wt .-% zinc metatitanate contains. . 3. Process according to claim 1, characterized in that tetrasodium-4,4 ^f -'bis / " _i / 4- (2-hydroxyethylamine) -6- / 7m (and ρ) -sulfoanilino j7-s-triazine is used as the brightener -2-yl '£ amin_7-2, ^2' -stilbendisulfonat used. 4. The method according to claim 2, characterized in that the brightener is disodium-4 _i 4'-bis / ^ * ^ - anilino-6- / bis- (2-hydroxyethyl) & Ta.lnojy-s-trl & zln-2-yl_yamln <} J7-2 , 2 'stilbene disulfonate used. 009828/1585