CS203160B2 - Method of manufacturing paper - Google Patents

Description

(54) Method of making paper

BACKGROUND OF THE INVENTION The present invention relates to a method of making paper with an increased degree of whiteness.

To obtain a maximum degree of whiteness, the paper industry has various methods available, such as selecting high white semi-paper, bleaching raw materials, using fillers or white pigments, tinting dyes and / or optical brighteners.

The high demands nowadays on the quality of the final product, especially in the field of printing paper, lead to an increase in the quality requirements of the fillers and pigments used. The addition of fillers and pigments is limited by increasing the paper's double-sided properties, increasing screen wear, but especially reducing the strength properties. The deterioration of the strength properties by the addition of fillers or pigments occurs because the fiber surface bonds are broken.

The choice of fillers and pigments to be added to the cellulose must take into account the particle size and shape, the hiding power and clarity, the low abrasion, the uniformity and purity of the material supplied, and other factors.

Properties such as binding requirements, dispersion properties and favorable theological behavior are also important for coating pigments.

In view of these limitations for filler and pigment additives, so-called optical brighteners have been increasingly used in recent years, thereby increasing the degree of whiteness of the pulp, as well as ground pulp and paints.

Optical brighteners do not overlap the yellow shade of the paper, but replace the lack of reflection with additional light due to their fluorescence. Optical brighteners shift the shade of the brightened material, for example from yellow towards blue, and an increase in reflection then increases clarity. Brighteners fluoresce sufficiently only when incorporated in substances on such materials as cellulose, starch, casein, polyvinyl alcohol, plastics such as polyvinyl acetate, or the like.

The use of optical brighteners presents difficulties as fillers and pigments generally reduce the brightener efficiency in paper by absorbing in the UF region or having a yellow hue. In addition, the effect of reduced performance with fillers and pigments is associated with their refractive index and hiding power.

It is an object of the present invention to provide a process for making paper in which the undesirable effect of fillers or pigments on optical brighteners is reduced or substantially eliminated while increasing the degree of whiteness, while increasing the retention properties of the materials used and the strength properties of the paper.

The invention solves this problem in a manner in which the pulp is crushed and conventional additives such as fillers, pigments, fibers, optical brighteners, etc. are added. 1% by weight, preferably 0.1 to 0.3% by weight, based on the additive used. To the conventional anionic brighteners used in the paper industry, a polypiperidine halide, which is adsorbed in a dispersed state on a fine particle carrier, is added. In a particular embodiment, the polypiperidine halide is polypiperidine chloride or polydimethyldiallylammonium chloride. If desired, bromides can also be used.

Contrary to expectations, it has been found that the effectiveness of optical brighteners can be greatly enhanced by minute amounts of cationic polymer, polypiperidine chloride, and that when fillers and / or pigments are used, the prior cationic polymer admixture improves or even allows significant enhancement of optical brighteners, thereby brightening become highly effective.

Carriers which are used for polypiperidine halides can be either finely pulverized inorganic materials, e.g. fillers such as kaolin, talc, and white pigments such as calcium carbonate magnesium silicate, aluminum silicate, calcium silicate or silica gel, or organic fillers such as starch, carboxymethylcellulose, fine cellulose fiber particles of varying degrees of crushing, or fine mechanical mechanical cellulose particles.

Especially - advantageous. -. is to suspend the filler or pigment or organic carrier and polypiperidine halide in an aqueous solution and add such a suspension to the pulp, e.g. in a vat - or a holander, or to a paint - for the paper, before optical brighteners are added.

According to a particular embodiment of the invention .... prior to the addition of the optical brighteners, the aqueous solution of the polypiperidine halide is added directly to the pulp, the particles of which serve as the polymer carrier.

The optical brighteners used in the paper industry are anionic substances, derivatives of diaminostilbendisulfonic acid, preferably condensation products containing triazine ring compounds are used.

It is particularly preferred that the polypiperidine halide is used in the presence of starch, especially in amounts where the starch is cationized or partially cationized.

It is sufficient if a small amount of polypiperidine halide, in particular polypiperidine chloride, is used to obtain the activity according to the invention. Suitable amounts are, for example, from 0.05 to 1% by weight, preferably 0 ', 1 to 0.3% by weight, of the polypiperidine halide, based on the pigment or filler.

If starch is used, the following amounts are used: 0.1 to 1.0% by weight, preferably 0.5 to 1% by weight of starch, and 0.05 to 1% by weight of the polypiperidine halide based on the pigment or filler. The substances are heated in an ^aqueous: medium to a temperature between 40 and 70 ° C, after "cooling is added -a- norganický or organic carrier and then the thus treated material is brought to> - contacted with an anionic optical brightener.

The invention is explained in more detail by way of examples. The polypiperidine halide used in the examples is polypiperidine chloride or polydimethyldiallylammonium chloride (see M. Fred Hoover and Hugh E. Carr: "Performance-Structure Relationships of Electors", Conductive Polymers, Tappi, The Journal of the Technical Association of the Pulp & Industry, Vol. 51, No. 12, December 1968, pages 552-559; U.S. Pat. No. 3,288,770), hereinafter referred to as "cationic polymer".

Přikladl ...............

The cationic polymer was introduced onto the pigment surface by dispersing various pigments which were suspended in water at room temperature (20 to 60 weight percent particles) and listed in Table I below in an aqueous solution of 1- to 10 weight percent cationic polymer. polymer. After introduction of the cationic polymer onto the pigment surface, an optical brightener, a commercial brightener (a diaminostilbene disulfonic acid derivative of Blakopkophor from Bayer A) is added. To this, starch is added if desired after pretreatment with the cationic polymer. in the quantities shown in Table I.

In practice, the procedure is as follows:

The pigments are dispersed in water in a beaker with stirring. The solids content is adjusted, depending on the type of pigment and the resulting viscosity, to be between 20 and 60 weight percent solids. An aqueous cationic polymer solution or a mixture of an aqueous cationic polymer solution with starch is then slowly added dropwise (with interruption) to the pigment suspension. In order to ensure uniform adsorption, the mixture is stirred for about 10 minutes before optical brightener is added. Subsequently, the pre-dissolved anionic optical brightener is added slowly and continuously with stirring.

After further stirring for 10 minutes, the brightening effect is clearly noticeable in

UF light. The product thus prepared can be used directly in the form of a suspension in a pa- and used in the manufacture or treatment of paper, feathers, eg in a vat or a holland, or can be obtained:

be dried first and then ground

T abu 1 к а I sample% cat. Polymer% optical brightener WG * ¹ based on pigment based pigment

papermill kaolin A-- 0.15 84.2 paper kaolin 0.5% starch 0.3% cat. Polymer 0.15 88.3 coating clay В - 0.15 87.6 coating clay В 0.2% starch 0.2% cat. Polymer 0.15 88.5 Al-Silicate C - 0.15 77.5 Al-silicate 0.5% cat. Polymer 0.15 79.3 Al-Silicate C 0.7% starch 0.5% cat. Polymer 0.15 80.9 СаСОз D - 0.15 92.8 СаСОз D 0.2% polymer cat 0.15 97.8 СаСОз D 0.1% starch 0.1% cat. Polymer 0.15 97.6 СаСОз D 0.5% starch 0.2% polymer cat 0.15 98.4

*> WG = repho degree of the whiteness meter measured on an Elxenon lamp

It can be seen from Table I that by using cations both with and without the use of starch, the brightness increases from about 3 to 5 points.

The characteristics of the pigments and fillers used are shown in Table II below.

Table II

sample Chemical composition degree of whiteness particle size (nm) spec, weight refractive index (n) specia, surface (m ² / g) paper kaolin Al2O3.SiO2.H2O 84.2 1—5 2.6 1.56 6.8 coating clay В Al2O3.SiO2.H2O 87.6 0,5—2 2.6 1.56 11.5 Al-Silicate C - - 77.5 1—2 2.1 1.48 140.0 chalk D СаСОз 92.8 0.5-2 2.7 1.56 8.0

Example 2

According to the method described in Example 1, the cationic polymer treated calcium carbonate was contacted with different types of optical brighteners at different concentrations.

Table III

sample % cat. polymer based on pigment % of optical brightener t based on pigment degree of whiteness СаСОз 0.2 0.05 optical brightener I ¹ ' 94.8 СаСОз 0.2 0,1 dtto 96.5 СаСОз 0.2 0,15 dtto 97.8 СаСОз 0.2 0.1 optical brightener II ²⁾ 96.3 СаСОз 0.2 0,15 dtto 97.4 СаСОз - 0,15 dtto 93.3

υ “Tinopal” from Ciba — Geigy AG (aminostilbenesulfonic acid derivative) ²¹ “Blankophor P” from Bayer AG (stilbendisulfonic acid derivative)

Example 3

American kaolin (1540 g) was dispersed with a high-speed stirrer

1.5 g of polyphosphate (Calgon PTH) on 70% slurry. Similarly, 660 g of superfine ground natural calcium carbonate was dispersed in a 70% slurry using a high shear mixer using 4.0 g of a polyacrylate dispersant (Polysalt CA from BASF).

The calcium carbonate slurry is mixed with the non-kaolin slurry to obtain a mixture of kaolin with calcium carbonate (70:30) in liquid form. About 9-10 ml of a 10% sodium hydroxide solution is added to the pigment mixture to adjust the pH to about 9, i.e. to a strongly alkaline pH. 101 g of a 10% dispersion of ammonium stearate, 514 g of a 30% cooked potato starch solution whose viscosity is adjusted by amylase, 137 g of 46% styrene-butadiene-late xu (XD 8417 from Dow Chemicals), are then added under continuous stirring. g of a stilbendisulphonic acid derivative (Blancophor P from Bayer A. -G.) as an optical brightener and 18 g of 80% melamine-formaldehyde resin (PPotex) are added as a hardener. This batch is prepared twice. As a last component, 5.5 g of polydiallyldimethylammonium chloride in the form of a 40% aqueous solution are added to one batch under intensive stirring.

Both coatings are applied to sizing raw paper containing technical cellulose at a speed of 500 m / min in an amount of about 10 g / m2 using a laboratory applicator (helico-ater). The weight of the base paper was about 70 g / m 2. The coated paper was smoothed after coating with a laboratory dutch (Kleinwefer) at a temperature of about 60 ° C and a linear roller press at a pressure of about 210 kp / cm ² . The smoothness of the coated paper was determined by the Bekk tester, the gloss at 45 ° with a Zeiss goniophotometer, the whiteness and opacity of the Zeiss Elpre - xenon lamp apparatus.

The results obtained are shown in Table IV below.

Table IV% Cat. Polymer based on pigment invention comparison solids content% viscosity η 100 (s ^-1 ) (st) pH

WRV ¹ '(s) smoothness (s) gloss 45 ° ·

WG’2 ’- (fiber lamp)

WG2) (xenon lamp) clarity ³ 'coating weight (g / m ² ) micro-outline test ⁴ '

58.2 4200 7420

8.7 1’34 ”1610

7.0

75.4

76.6

82.0 very good

59.2 1480 2400

8.9 1’52 ”1660

6.1

73.6

75.9

80.4 good ¹¹ water retention capacity

2) degree of whiteness

3) brightness measured by Zeiss “Elrepho”

4) to evaluate the wettability of the printing ink

Contrary to expectations, it has been found that the use of minute amounts of a cationic polymer (polypiperidine halide, particularly polypiperidine chloride) significantly improves the retention properties of fillers, pigments and fibers, as well as the strength characteristics of paper.

In addition, natural starch can be economically - partially or totally - catalyzed by cationic polymers. Cationized starch has better retention and strength properties.

The advantages achieved by using cationic polymers are apparent from the following examples.

Example 4

For carrying out the sheet production test, - on a sheet production RK (Rapid-Koethen), the following cellulose is prepared:

% by weight of kraft cellulose, bleached by weight% of sulfite cellulose, bleached by weight% beech cellulose, bleached

SR degree * ': about 35 ° SR filler: kaolin, calcium carbonate (unprocessed in some cases, others pre-treated with cationic polymers) pH value: 5.5 for kaolin tests pH value: 7.8 for tests with calcium carbonate ^#) SR degree - Schopper — Riegler grinding degree (drainage rate)

In all cases the same starting amount of filler (about 30 weight percent based on dry fiber weight) was added.

The results obtained in the sheet production tests are shown in Table V.

Table V filler retention (ash%) tear length (m) along. cross-processed kaolin14,4 kaolin with 0,2% cat. polymers16,1 kaolin with 0,5% cat. polymers17,5

СаСОз unprocessed11.0

СаСОз with 0.2% cat. Polymers13.1

2450

2590

2350

2620

2710

2100

2250

2080

2190

2250

Table V shows that due to the positive charge of the filler - caused by the cationic polymer - better adsorption or retention occurs on the negative fiber. In the mixture of the unprocessed filler and the treated filler, the unprocessed kaolin has better retention due to the charge balance. Among the known consequences of improved retention properties are longer screening times.

The treatment of the filler or pigment with cationic polymers is carried out according to the method described in Example 1 for practice.

Strength characteristics are usually adversely affected by the addition of fillers, since surface bonds - hydrogen bonding between the cellulosic fibers - break up, which means that the strength decreases with increasing filler content. However, contrary to expectations, after the cationic polymer fillers have been pretreated, there is some increase in strength despite the increase in filler content. This may be due to the interaction between the fibers and the polymer on the surface of the filler, as opposed to the unprocessed filler. This result is of particular importance since, especially in the case of low grammage papers, great difficulties arise in the treatment and manufacturing process due to its strength properties.

The improvements achieved by the use of cationic polymers due to the cationization of natural starch are given in the following Example 5.

Example 5

a) Experiments in the production of sheets on the RK sheet making machine

Cellulose composition:

weight% mechanical technical cellulose, bleached weight% kraft cellulose, bleached pH value: 7.0 degree RS: about 40 ° SR

The following were added to the cellulose blends:

And 5 ml of 10% by weight natural potato starch

In 5 ml of 10% by weight natural potato starch mixed with 1% cationic polymer and heated

C 5 ml 10% by weight of natural potato starch, mixed! with 3% cationic polymer and heated D 5 ml 10 wt.% natural braided starch mixed with 5% cationic polymer and heated.

The weight of the sheets produced was in all cases 2.4 g.

Strength test: breaking load according to DIN 53 112 paper sample A 2,8 kp paper sample В 3,2 kp paper sample C 3,5 kp paper sample D 3,5 kp

The results show a marked increase in the strength properties of the cationic starch samples compared to the natural starch sample.

b) Attempts to produce sheets on an RK sheet making machine

Cellulose composition:

% by weight mechanical technical cellulose, bleached% by weight sulfone cellulose, bleached pH value: 7.0

SR degree: around 40 ° SR

The following were added to the cellulose blends:

And 1 ml of 10 weight percent natural potato starch

Β 0.5 ml 10% by weight of natural potato starch, mixed with 5% by weight of cationic polymer and boiled for a short time

C 1 ml 10% by weight natural potato starch mixed with 5% by weight cationic polymer and cooked for a short time.

% by weight of optical brightener (based on 2.4 g = leaf weight) was added to each of the above mixtures (A, B, C).

Degree of whiteness: measured ^ on the “Elrepho” instrument with xenon lamp.

paper pattern degree of whiteness AND 79.2 (B) 80.5 C 82.5

Cationization of starch - in both fillers and coating pigments - improves the whiteness level.

When the cationized starch and the optical brightener are premixed, the brightening effect is largely reduced. The same was observed in terms of paper strength.

The application of adhesive layers to papers that are dried and which can be glued by moistening and bonding with other material, such as paper, is called "sizing".

The improvement in adhesive properties using minute amounts of cationic polymer is evident from the following Example 6.

Example 6

15% by weight of the swollen starch "solution" in water and 15% by weight of the aqueous "solution" of swollen starch, which has been pretreated with 5% by weight of cationic polymer, are applied to paper and dried. The adhesion force is tested after wetting with an adhesive force tester "Figapo" (PKL).

sample with normal swollen starch (potato starch) 2,9 mmkp sample with swollen starch (potato starch), pre-treated with 5% by weight of cat. polymer 8,4 mmkp. The pre-treated sample exhibits excellent film-forming properties.

A good adhesive bond is considered to have a strength that binds the materials together. This requirement is met if pre-processed starch is used but not normal starch.

Usually, 0.5 to 6% by weight of the starch to be used for the adhesive bond is preferred, preferably 1 to 5% by weight of polymer (based on the weight of the paper fibers) is preferred. .

It is usually preferred that the above-described applications of the cationic polymer (halide · polypiperidine, especially polypiperidine chloride) be carried out with aqueous solutions containing 1 to 10 weight percent of the cationic polymer.

Claims (6)

OBJECT OF THE INVENTION A process for the manufacture of paper in which the pulp is crushed and added to it with conventional additives such as fillers, pigments, fibers, optical brighteners, etc., characterized in that a polypiperidine halide is added to the pulp in an amount of 0.05 up to 1% by weight of the additive used. 2. The method of claim 1, wherein:. Polypiperidine halide · adsorbed on dispersed powder. porters. 3. The process of claim 2 wherein the adsorbed polypiperidine halide is added to the stock prior to addition of the optical brightener. 4. The process of claim 1, wherein the polypiperidine halide is first reacted with starch by heating in an aqueous medium at a temperature of 40-70 [deg.] C. and then cooled and then added to the stock. 5. A method according to claim ¹ 4, characterized in that 0.1 to 1.5% by weight ·, preferably 0.5 to 1% by weight of starch and 0.05 to 1% by weight polypiperidine halide, based on the ingredient. 6. A process according to any one of claims 1 to 6, wherein the polypiperidine halide is polyplperidine chloride. polydimethyldiallylammonium chloride.