FI72558C - ANVAENDNING AV SERPENTINIT SOM TILLSATSAEMNE. - Google Patents

Description

1 72558

USE OF SERPENTINITE AS AN ADDITIVE

This invention relates to the use of finely divided serpentinite as an additive in the paper industry, either as an additive for paper and board, either as a filler for paper and board, or as a resin, resin extractant and other so-called as a tackifier and zero fiber collector both in the paper industry itself and in the process waters of the paper industry. Serpentinite can be used alone for these purposes or in admixture with a suitable substance, e.g. talc.

The use of fillers in the paper industry is primarily aimed at replacing some of the expensive wood fiber material with cheaper mineral material, but fillers also affect many properties of paper and board, either improving or deteriorating them.

Fillers improve several properties of paper and board in terms of both optical and printability. In addition to saving wood fiber, the main purpose of fillers is to improve opacity, brightness, printing ink adsorption, surface smoothness, print smoothness, porosity, paper feel, and paper and board friction, stiffness and lying. Other effects include increased density, improved dimensional stability, and flattening of the paper base.

The filler is usually also required to have a high porosity, mainly due to its printing properties. The ink penetrates better into the porous material, which also has a large specific surface area. Fillers increase the fire resistance of paper and board. If the filler-fiber network is as dense and durable as possible, the refractory properties are good.

Fillers generally degrade the strength properties and adhesive strength of paper and board. Large additions of filler can cause dust to dust on the paper machine dryer, cutter, and calenders. Dusting is due to the deteriorating effect of the surface strength of the fillers and can be prevented, for example, by the addition of starch or surface sizing.

The main fillers currently used in paper and board are kaolin, talc, gypsum, chalk, calcium carbonate, barium sulfate diatomaceous earth, titanium dioxide, zinc sulfide, aluminum hydroxide, montmorillonite, and synthetic silicates.

2 72558 The main weakness of fillers is their poor adhesion to the street network. The main reason for this so-called poor retention of fillers is that the zeta potential of most fillers is negative as well as that of the fibers. For this reason, the filtration effect retaining the filler particles of the fiber network is the most important factor influencing the retention. The filtering effect, in turn, is determined by the thickness of the pulp web passing through the wire, the density of the fibrous web, and the amount of suction applied to the web.

On the other hand, retention is also affected by the physical properties of the filler particles. Large particles leach better than small ones that easily pass through the filtration layer. The elongated or fibrous shape is more advantageous to the particle in this respect than the spherical one. Heavy particles leach worse than light ones.

One of the problems in the paper industry is the resin, resin and extractants that come into the process with the wood fiber material, and especially the sticky substances that come with the recycled material, the recycled fiber. Adhesives consist of various hot melt adhesives, waxes, adhesive tapes, bituminous impurities and resin. All of these adhesives cause numerous disadvantages both on the machine and in the product: The adhesives adhere to the pores of the felt on top of the wire and thus gradually prevent water from filtering through the felt. In this case, too much water tends to remain in the mass. Sticky substances adhere to the rollers of the machine during the driving phase when the temperature on the machine rises (max. 130 ° C). Adhesion of the adhesives is visible in the drying cylinders as brown zones. As a result, the appearance and durability of the final product deteriorate.

In order to remove sticky substances, e.g. alum, sulfuric acid, resins, adhesives, urea-based products, phosphate or nitrate-based products ammonium salts, chrysotile and talc. An example of the use of chrysotile is the 5U inventor's certificate 579 367. which also mentions the use of serpentinite and brucite as an additive to chrysotile as a zeta potential enhancer. Talc is currently perhaps the most widely used resin and tackifier removal chemical. The reasons for the difficulties in removing sticky substances are e.g. the fact that the sticky substances detach from the surface of the circulating fiber in the form of larger plate-like pieces. The talc used to remove the extractants is not effective for such very sticky particles. Unlike sticky substances, the extractants are dispersed in small droplets. which minerals can bind. The sticky particles have a very light specific gravity of 3,72558 (density 0.8 to 0.9 g / cm 3, lighter than the fiber), so they do not leave in vortex separators. To remove sticky matter, the mineral material should be able to coat the sticky particle well on all sides to increase its specific gravity. In this case, the adhesive particle could be removed from the process in a vortex separator. If the sticky particles are left incomplete to coat the mineral, it will "melt" more easily as the temperature rises as the process progresses.

According to the present invention, serpentinite can be successfully used in the paper industry both as a filler for paper and board and as a remover of resin, resin extractants and other tackifiers, as well as a collector of zero fibers. The essential features of the invention appear from claim 1.

Serpentinite is at its purest monoclinic fine crystalline magnesium silicate. serpentinine [(OH) 2 Mg 3 (Si 2 O 5)]. The lattice often contains iron and aluminum. The amount of metals, especially iron, in the lattice determines the color of the serpentinite and thus the degree of brightness. Serpentine belongs to the so-called. mesh silicates and most often occurs as a matte, soft and finely divided mass. Some serpentinite grades are softer than talc. The serpentine network consists of a single layer of silicon tetrahedron, the negative charge of which is neutralized by the so-called brusiittikerroksella. Talc has two fewer hydroxyl ions per magnesium ion, and the brucite layer receives an additional positive charge that is neutralized by a second hexagonal silicon tetrahedron layer.

When serpentinite is crushed and ground, positive charges are created on the surfaces of the serpentine. Talc, on the other hand, remains almost neutral or loses its charge in the slurry, remaining easily hydrophobic. The unusually high slip of talc is due to two possible sliding surfaces. The serpentine is not as slippery due to only one sliding surface. Slipperiness is an advantage if the paper is polished, but in many cases it is also a disadvantage if the paper is made into more complex products such as various packaging products. Due to its softness, serpentinite does not damage or scratch machines when calendering or with drying cylinders.

The fibers of the pulp have a negative zeta potential. The zetapotential of serpentine, on the other hand, is positive (> + 10 mV) and this property is very relevant for filler use, tackifier removal and null fiber twists as serpentine adheres well to the fiber network. In this case, the serpentine also contributes to the binding of fine zero fiber. Thus, the filtration effect of retaining the filler particles "72558 of the fibrous network is not so important for retention. The crystalline form of serpentine is also preferred for retention. The serpentinite used as a filler does not need embryonic chemicals to adhere to the fiber surface.

Adhesion to the surface of the fibers in serpentinite is facilitated by its exceptionally large specific surface area, which is 50,000 to 500,000 cm 2 / g, as the case may be, and its high porosity. The high melting point of serpentinite (about 1400 ° C) and its change as the crystalline water gradually evaporates to the molten state gives serpentinite account to filled or coated paper good refractory properties. The porosity of serpentinite also allows the addition of heat consuming additives.

One advantage of serpentinite is its hydrophilicity, which results in easy sludgeability, which facilitates the processing of the mineral material. The softness of serpentinite, on the other hand, has the advantage that it is possible to use a larger grain size than fillers in general, and the large grain size of serpentinite increases the stiffness and thus reduces curl in e.g. envelope paper.

Serpentinite has several advantageous properties for the removal of sticky and fresh resin: serpentine has a positive zeta potential, so it easily adheres to the surface of sticky particles, is easily slurried (hydrophilic), has a high specific surface area and porosity.

Thus, serpentinite can be used in the paper industry both for the removal of fresh resin and extractives from fresh wood, in particular in the production of groundwood and thermo-pulp, and for the removal of sticky substances associated with circulating fibers. The addition of serpentinite is carried out according to the factory conditions, e.g. to a pulper, grinders, a suitable pulp type close to the headbox of the machine or to the suction side of the circulating water pump or to a pulper in the case of circulating fibers. The adhesive particles can be "coated" so completely into the serpentinite that they can either be removed from the process before the filter presses and the drying section cylinders, e.g. with scrapers, or the adhesive particle is inerted so completely into the serpentinite that it can pass through the machine without interfering with the process.

Modern paper mills have closed circulating water systems and the fresh resin and stickies that enter the process are enriched here. In this case, from time to time comes the so-called. closure limit. Serpentinite can also be used to separate the resin and stickies in these circulators. Once the serpentinite has adsorbed on the surface of the adhesive particle, it can be easily separated from the water, e.g. by foaming or settling.

The grain size of serpentinite plays an important role in the removal of tackifiers, as finely ground serpentinite stays in the coarse particle to better coat the tacky particles, making it last longer without melting on a paper machine than a particle without this protective layer.

Experiments have shown that serpentinite increases the friction of the paper and does not impair its tensile strength like fillers in general. This is due to the positive zeta potential of serpentinite, resulting in a strong bond between the serpentinite particle and the negatively charged fiber. Due to its good friction and strength properties, serpentinite is a preferred filler in e.g. construction papers, industrial wrappers, testliners, corrugated board and coreboard.

The color of serpentinite places its own limitations on its use as a filler and tackifier in the paper industry. Serpentinite is usually gray in color. If high requirements are set for the color of the paper, light serpentinite can be used as a filler. Another possibility is to mix the serpentine rivet in the required proportions with the talc, e.g. in connection with a double layer coating. If part of the amount of pulp is recycled fiber, the removal of sticky substances is important. In this case, talc can be completely replaced by serpentinite with a higher specific surface area and adsorption capacity. In the paper industry using recycled fiber, e.g. in the sack industry, the increase in friction caused by serpentinite is an essential advantage.

In addition to removing or inerting sticky particles, serpentinite can be used to remove ink particles and ink residues during pulp deinking.

The amount of filler in paper and board varies considerably depending on the type of paper involved. In offset paper, the amount of filler is 0-10% of the total pulp. Instead, the amount of filler in LWC paper is 35 -40% and in some wallpaper paper grades up to 50%. As already stated above, in other cases either serpentinite can be used as a filler or it can be used, for example, mixed with talc 72558

The amount of tackifier used is relatively small compared to the total paper weight, usually 0.5 to 20%. In contrast, the properties of serpentinite as a resin, extractor and tackifier are better than those of known tackifiers. Thus, the known tackifiers can be replaced either completely or for the most part by serpentinite. As the dopant, e.g. talc used for this purpose can be used.

Example 1 (so-called comparative example)

As a comparative example, ordinary brown pine sulfate pulp made for making sack paper has been used. The properties of the pulp are described by the following indices: basis weight 108 g / ir> 2j porosity Gurley 90 s / 100 ml: tensile index 75 elongation 6.7% tear index 12.0 ash 0.4% columnar strength -302 [3 / m 2]

Taber abrasion 10.7 [mg / 1000 g / 25 rpm] plate dry. x density 746 [kg / m 2] and coefficient of friction on the glossy side 0.39 and on the rough side 0.39.

Example 2 Paper friction (cf. example 1)

The friction of the paper is significantly increased when serpentinite is used as a filler. With a serpentinite addition of 10%, the friction on the rough side of the paper increased to 0.50. On the glossy side of the paper, the friction rose to 0.42. In both cases, the friction of the paper increased undeniably.

Example 3 Paper stiffness

The stiffness of the paper could be clearly increased by the addition of serpentinite. The softness, grain shape and adhesion of the serpentinite to the fibers allowed the use of larger grain sizes e.g. -10 μm 40% and -20 μm 100% compared to conventional fillers e.g. talc and kaolin -10 μm 90%.

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Example 4 Paper strength properties (cf. example 1)

The following measured indices show a significant preservation of the strength properties of the paper despite the additions of serpentinite used as a filler. The specific surface area of the serpentine rivet was very high 46 m 2 / g. With a serpentinite addition of 10%, paper ash rose to 4.3%.

(a) Traction index

With a serpentinite addition of 5% of the amount of fiber, the tensile index has hardly changed and is still 74. When the increase is 10%, the effect of the increase can be seen numerically, the value of the tensile index is 68. In the actual so-called the pulp masses have a noticeable change in the tensile index only with an increase of 15%.

b) Elongation

With a serpentinite addition of 10% of the amount of fiber, the elongation of the paper has remained the same with the addition of 0.5%, or 5.8. The elongation of the paper has decreased slightly and it can be stated that the 10% increase has not yet had a negative effect on the elongation of the paper.

c) Tear strength

With a serpentinite addition of 10% of the amount of fiber, the tear strength of the paper has remained the same as with the addition of 0.5%, i.e. 12.4. The tear strength has remained virtually unchanged. An increase of 10% has not had a detrimental effect on tear strength.

d) Puncture resistance

With a serpentinite addition of 10% of the amount of fiber, the puncture strength of the paper has remained the same as with the addition of 0.5%, i.e. the puncture resistance has also remained unchanged. An increase of 10% has not had a detrimental effect on puncture resistance.

Example 5 Resins, resins, extracts and other so-called removal of sticky substances (hereinafter commonly referred to as sticky particles)

Serpentinite could be found to adsorb to the surfaces of sticky particles.

Adsorption was determined by scanning electron microscopy (SEM) and a microsanalyzer could be used to analyze serpentinite adsorbed on the surfaces of sticky particles by running, for example, line analysis of silicon (Si) over the sticky particles. In this case, the intensities of silicon (Si) were found to increase strongly for the sticky particles. Because serpentine was able to adsorb to the surfaces of sticky particles due to its exceptional s 72558 surface properties (high specific surface area and hydrophilicity), their adhesion to the so-called press felts on the wire section of the paper machine decreased. This, in turn, means a longer change in the press intervals of the press felts and thus direct cost savings. In addition, the adsorption of the sticky particles on the actual parts of the paper machine, such as the drying cylinders, was reduced because the sticky particles were covered with serpentinite adsorbed on the surfaces.

Example 6 Resins, resin extractants and other so-called removal of sticky substances by foaming of process waters (hereinafter commonly referred to as sticky particles)

The ability of serpentinite to adsorb to the surfaces of sticky particles provides an opportunity to remove sticky particles from process waters by flotation of the serpentinite adsorbed on the surfaces. Serpentinite is known to foam very easily over a wide pH range, but particularly easily over a near neutral range. In addition, serpentinite does not need any actual collector to flotate, but only a small amount of flotation oil. In the experimental foams performed, it was found that most of the sticky particles were removed with serpentinite in the foam. The sticky particles left in the process water were adhered to the equipment used in the experiments. Tests performed by flotation without flotation also gave similar results.

Il

Claims (8)

72558 Finely divided serpentinite, the active ingredient of which is serpentine [(OH) 2 Mg 3 (Si 2 O 2)], characterized in that the fine serpentinite is used as an additive in the manufacture of paper or the like 0.5% to 50% by weight of the total pulp. Use according to Claim 1, characterized in that the serpentinite is mixed with talc in different proportions. Use according to Claim 1, characterized in that serpentinite is used as a paper filler. Use according to Claim 1, characterized in that serpentinite is used as a filler for the board. Use according to one of the preceding claims 1 to 4, characterized in that serpentinite is used as a remover of resin, resin, wood extractants and other adhesives. Use according to Claim 5, characterized in that serpentinite is used as a tackifier in the circulating paper industry. Use according to Claim 5 or 6, characterized in that serpentinite is used as a resin, resin, extractant and tackifier 1.5 to 20% by weight of the total pulp. Use according to Claim 1, characterized in that the serpentinite is used as a zero fiber collector.