FI59808C - FOER FRAMSTAELLNING AV WELLPAPPLIM LAEMPLIG HUVUDSAKLIGEN STAERKELSE INNEHAOLLANDE AEMNESKOMPOSITION - Google Patents

Description

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Patent · oeh registerstyrelsen Antökan utlagd oeh uti. «Krift * n pubik« r * d 30.06.81 (32) (33) (31) l * yy4itty Muolkeut —Begird prtorltet (71) Oy Vehnä Ab, 21200 Raisio, Finland-Finland (Fl) (72) Kai Hannus, Turku, Mikko Maijala, Ihala, Martti Söderström,

Turku, Suomi-Finland (Fl) (7 ^) Oy Jalo Ant-Wuorinen Ab (5M A combination of substances suitable for the manufacture of corrugated board adhesives, mainly containing starch - For use in the manufacture of corrugated cardboard adhesives, fun-filled starch-based composite compositions

The invention relates to a combination of substances suitable for the production of corrugated board, mainly containing unmodified starch, which, when slurried in water, binds considerably more water than ordinary unmodified starch in the same concentration as water slurry. from ordinary unmodified starch to similarly prepared corrugated cardboard films.

Corrugated board adhesives made of unmodified starch are already known, which consist of two components, namely a starch component containing unmodified starch in non-gelatinized and non-swollen form, and a base of a component which is separately prepared by gelatinizing unmodified starch and non-modified starch. In addition, viscosity-increasing and stabilizing mineral fillers, such as bentonite, have often been used in these two-component adhesives. These adhesives are described, inter alia, in the following Stein-Hall method patents: U.S. 2,051,025 (1936), U.S. 2,102,937 (1937) and U.S. 2,212,557 (1940).

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The use of chemically modified high-viscosity starches as a carrier component for corrugated board adhesives is also known. These starch transformations are prepared by reacting unmodified starch with intermolecular cross-linking chemicals to give modified starches which, when heated in an aqueous slurry, give highly viscous gels. Known crosslinking chemicals include dimethylol urea, formaldehyde, melamine formaldehyde, epichlorohydrin, trichlorotriazine, sodium stannate, and phosphorus oxychloride. Said modified starches are described in U.S. Pat. No. 2,407,071 (1946), U.S. Pat. No. 2,500,950 (1050), U.S. Pat. No. 2,805,220 (1,057), U.S. Pat.

2,113,034 (1938), U.S. 2,417,611 (1947) and U.S. 2,468,207 (1949). In addition, pregelatinized starch and natural or synthetic gelling agents such as alginates or carboxymethylcellulose have also been used as a carrier component for corrugated board adhesives, especially in dry mixes which the user only needs to slurry into water as a ready-to-use adhesive. Modified starches with lower than normal viscosities have also been proposed for the preparation of the carrier component. They are prepared by treating unmodified starch in aqueous slurry with dilute acids, so that due to slight hydrolysis they have a weakened internal structure, and their grains decompose more easily than grains of unmodified starch when heated in aqueous slurry to obtain a more completely gelled product. These modifications are presented, inter alia, in the article "Special starches for Corrugating" by B.L.Sallall and E.A.Sowell, TAPPI 4_2, 1 959, pages 203 ... 205.

Corrugated board adhesives made of unmodified starch are also known, which are made from a single starch component by swelling it in an aqueous slurry with an alkaline substance and heat to act as their own carrier under conditions such that the starch does not gelatinize during manufacture. They have been described e.g. in the following patents: US 3,355,307 (1967), GB 1,079,387 (1970), DE 1,567,363 (1970), FI 43,973 (1971), US 3,524,750 (1070), GB 1,302,942 (1973) and SE 371 832 (1974). It is further known to produce a corrugated board adhesive from a single starch component by swelling it in an aqueous slurry solely by heat, FI publication 53 221.

All of the corrugated board adhesives made from starch described above use starch purified from other materials such as proteins, as far as the prior art allows, as the starch raw material.

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Since the adhesive slurry consists mainly of water-insoluble starch grains, it is in principle always possible for starch grains heavier than water to separate in the slurry during adhesive storage, recycling, pumping and especially temperature fluctuations, forming at least two layers of different starch concentrations. This has been found to occur almost whenever errors in the manufacture of the adhesive have occurred due to imperceptibility or error. This is particularly detrimental because re-uniformizing the adhesive takes a lot of time and may even be impossible.

Another problem is to maintain the viscosity of the adhesives in a limited viscosity range suitable for the corrugated board machine under mechanical stresses on the adhesive and / or when the temperature of the adhesive varies or during the storage of the adhesive. In adhesives consisting of a single starch component, the problem has been solved by swelling the entire amount of starch in the aqueous slurry to a certain viscosity with either alkaline and heat or heat only, after which swelling must be stopped, otherwise the reaction will continue, starch will start to gelatinize The viscosity balance achieved in this way, especially in alkaline adhesive sludges, can be easily altered due to influences such as mechanical stress, temperature variations or changes in pH. Two-component adhesives are more reliable in terms of their viscosity stability because they have a separate carrier component with an intrinsic viscosity that is several times that of the final adhesive. However, they have been considered to be less favorable than one-component adhesives because the carrier component has not been considered to be involved at all in the gluing process itself on a corrugated board machine.

One of the factors limiting the use of the adhesive is also the price of the adhesive if relatively expensive modified starches or synthetically prepared products, such as polymer dispersions, which have not been discussed in more detail above, are used as components of the adhesive.

The object of the present invention is to provide a combination of substances suitable for the production of corrugated board, mainly containing unmodified starch, which, when slurried in water, binds considerably more water than unmodified starch in the same concentration as water slurry. .50 ° C compared to a corrugated board glue made in the same way from conventional unmodified starch, a combination of 4 59808 equipment, and which is inexpensive. The object is achieved by an adhesive composition according to the invention, the features of which appear from the appended claim 1.

When gluten is made from wheat flour according to the method according to pi 49 358 (1975), in addition to gluten and pure wheat starch, a product fraction containing mainly starch is obtained, which in said patent is called "lower quality starch". This product fraction, hereinafter briefly referred to as B-starch, contains, in addition to starch, 1 to 8% by weight of wheat pentosans and 1 to 10% by weight of proteins, based on the dry matter of the fraction. Pentosans are polysaccharides consisting primarily of the pentose sugars D-xylose and L-arabinose. The starch of the fraction has an unusually small grain size compared to conventional wheat starch, namely mainly less than 10 μm and mainly 2 ... 6 μη. Said small starch grains are largely associated with the "backbone" formed by pentosans and protein.

It has now been found that B starch binds an unusually large amount of water compared to conventional refined wheat starch. This can be seen with a so-called Bauman device comprising a glass sinter and a water tank connected to the sinter, to which the reduction of the amount of water in the water tank can be read from the connected measuring capillary. The water-binding capacity is measured by placing 40 mg of the test substance on a sinter that just touches the surface of the water in the water tank on its underside and reading the amount of water absorbed from the measuring capillary into the test sample through the sinter. The arrangement in Table 1 describes the water-binding capacity of the various product fractions obtained in the manufacture of wheat starch, measured with a Bauman device at a temperature of 22 ° C.

table 1

Product fraction Bound water- Ratio of the amount of water bound (ml) to the amount of fraction _ (ml / g) _

Fiber fraction + B-starch + waste 0.07 5 1, 9 B-starch 0.17 4.25

Pure wheat starch 0.01 0.25

Other conventional unmodified starches, the most commonly used being potato and maize starch, give similar results as wheat starch.

5 59808 The good water-binding capacity of B-starch is also manifested in that its aqueous slurries have a significantly higher viscosity than the aqueous slurries of conventional unmodified starches. Table 2 shows the viscosity of the aqueous slurry of B-starch as a function of dry matter content compared to pure wheat starch measured with a Brookfield viscometer at 25 ° C, spindles 1 to 6, speeds 50 and 100 rpm, the spindles and speeds being selected according to the viscosity range to be measured. .

Table 2

Dry matter of the slurry Brookfield viscosity (%) (mPa s) _B-starch_Wheat starch 10 20 20 20 50 22 22.5 70 24 24 120 25 26 220 27 28 570 30 30 1000 30 31 1500 32 32 2100 35 33 3000 35 1 60 45 120 47.5 240 50 1250 51 3400

From the above, it is obvious that B-starch is particularly well suited as a viscosity-increasing and stabilizing ingredient of corrugated board adhesive. In addition, it has been found that up to 90% by weight of the final mixture of conventional unmodified starch can be mixed with B starch, the viscosity of the resulting mixture in aqueous slurry in the concentration range of conventional starch corrugated adhesives being even higher than that of conventional unmodified starch. It has further been found that the stability of the obtained slurries, i.e. the ability to remain homogeneous, is clearly better than that of the corresponding aqueous slurries made of conventional 59,5808 starches. This can be stated, inter alia, in the following simple way:

Mix 20 g of starch into a slurry with water so that the total volume of the slurry is 100 ml. The sludges are mixed well to a uniform consistency and poured into beakers where they are allowed to stand for a specified time. The stability of the sludges can be evaluated by periodically measuring the amount of clear water layer developed on the top of the measuring glasses. When this experiment was performed with corn starch and mixtures of said starch and B-starch, the following results were obtained:

Amount of clear aqueous layer (ml)

Time Corn starch Corn starch 50% Corn starch 90% ___ B-starch_50% B-starch_10% 10 min 20 1 5 h 65 14 54

The lower the amount of clear water layer, the better the sludge stability.

Corrugated board adhesives can be prepared in a manner known per se, either as two-component adhesives containing a carrier component or as one-component adhesives without a carrier, using a combination of substances containing 10 to 100% by weight of B-starch and 90 to 0% by weight of conventional unmodified starch. It has been found that said corrugated board adhesives have a characteristic concentration-dependent viscosity which remains practically the same even after repeated heating-cooling cycles, i.e. when the adhesives are heated to temperatures of up to 50 ° C and cooled to temperatures of at least 10 ° C, and this treatment is repeated several times. It has further been found that when said adhesives are subjected to mechanical stress in the above-mentioned temperature range, their viscosity still remains practically unchanged. Such stresses include continuous mixing, pumping, recycling in the piping, and spraying through narrow nozzles. It has further been found that when two-component adhesives made from the combination of substances according to the invention are used for gluing corrugated board, gelatinized carrier starch also participates in the gluing process, especially in the formation of the initial bond while the glue joint is still wet. So far, 7 59808 cannot be conclusively explained, but it is likely that pentosans promote the adhesion of gelatinized starch to glued board surfaces. This also represents a considerable relief in the manufacture of one-component adhesives, since the swelling reaction inherent in their manufacture no longer necessarily has to be stopped, but a small proportion of the swollen starch can be safely allowed to gelatinize. Finally, it has been found that using adhesives made from the combination of substances according to the invention, a corrugated board machine can be run even at high speeds, up to 275 m / min and above, without a significant deterioration in the strength of the joint. In particular, the strength of the adhesive joint in relation to the speed of the machine is important in the production of multilayer corrugated board.

The invention is further illustrated by the following examples, which are intended to illustrate various embodiments of the invention, but do not limit the scope of the invention to that described in the examples:

Example 1:

Four Stein-Hall-type two-component corrugated board adhesives were prepared in a known manner from the following starch grades: The starch grain size was as follows: 2% over 10 μπι and 88% over 2 to 6, etc. Approximately 30 kg of each adhesive was recycled by pumping in a tubular system built into the laboratory while repeatedly heating to 50 ° C and cooling to 10 ° C. At the beginning of the test, the dry matter content and viscosity of each adhesive were determined, as well as the viscosity was determined periodically during recycling.All viscosity determinations were performed on samples adjusted to about 35 ° C by the Stein-Hall method known to those skilled in the art. what amount of glue is needed to drain a certain size hole through. The results were as follows: 8 59808

Adhesive Dry matter Stein-Hall viscosity (s) _ (%) _____ Oh 6h_1 2h 24 h A 18.7 48 41 37 35 B 18.8 47 45 45 44 C 18.6 50 45 42 41 D 18.7 45 44 43 44

Example 2;

Two Stein-Hall type adhesives were produced at the corrugated board factory. Reference adhesive A was made as follows:

Carrier component: 700 liters of water were heated to 65 ° C. 75 kg of unmodified wheat starch was slurried in it and 5 kg of sodium hydroxide dissolved in 10 liters of water were mixed. The slurry was stirred for 10 minutes at 65 ° C to gelatinize the starch. Starch component: 5 kg of borax was dissolved in 1600 liters of water and 425 kg of unmodified wheat starch were slurried and mixed for 30 minutes. The two components were combined and finally 2 liters of commercial formalin solution were mixed into the adhesive.

Test glue B was made in exactly the same way, except that 75 kg of B-starch containing 5.5% by weight of proteins and 4.0% by weight of pentosans were used to prepare the carrier component.

The Stein-Hall viscosities of the adhesives at 35 ° C at different times were as follows:

Adhesive Dry matter Stein-Hall viscosity (s) _____ (%) _ 0_h_5_ h_10 h A 16.7 38 33 31 B 16.8 36 37 36

Using both adhesives, standard quality single ply corrugated board was run at different speeds up to a top machine speed of 210 m / min. The strength of the adhesive joint was measured using a "Pin Adhesion Tester" commonly used by those skilled in the art to give the following adhesive joint strengths:

Machine speed Adhesive joint strength (kPa)

(m / min) _Adhesive A_Adhesive B

100 119.6 127.5 150 111.8 118.7 180 107.9 116.7 200 107.9 114.7 210 98.1 109.8 - * f * '·' · '9 59808

Example 3:

In the laboratory, a carrier-free one-component adhesive was prepared by the method described in FI 53 221 using a mixture of 15% by weight of B-starch and 85% by weight of unmodified wheat starch. B-starch contained 5.0% by weight of proteins and 3.5% by weight of pentosans and had the following grain size: 4.0% over 10 μm and 85% over 2 to 6 μm. wheat starch. The adhesives were recycled by pumping in a tubing system built into the laboratory while repeatedly heating to 50 ° C and cooling to 10 ° C. The Stein-Hall viscosities were:

Adhesive Dry matter Stein-Hall viscosity (s) _ (% J_Oh 5 h 10 h 20 h

Reference adhesive 18.5 39 35 34 33

Test adhesive 18.6 36 35 35 36

Using a test glue, a one-sided corrugated board 127 rpm / corrugated board and 2,150 g / m 2 kraftliner were run on a mini-corrugated board machine. The strengths of the adhesive joint at different machine speeds were as follows:

Machine speed Seam strength (m / min) _ (kPa) _ 100 139.3 150 141.2 200 133.4 250 138.3 300 119.6

Example 4:

A carrier-free One-Component Adhesive was prepared from a mixture containing 20% by weight of B-starch and 80% by weight of unmodified wheat starch. The B-starch used contained 3.5% proteins and 2.8% pentosans and had a grain size of 4.6% above 10 and 82% from 2 to 6. The reference adhesive was a commonly used carrier-free One-Component Adhesive made from corn starch. Both adhesives were recycled by pumping in a tubing system built into the laboratory while repeatedly heating to 50 ° C and cooling to 10 ° C. The Stein-Hall viscosities at different measurement times were as follows at 35 ° C:

Adhesive Dry matter Stein-Hall viscosity (s) _U) _0 h 5 h 10 h 20 h

Test adhesive 18.3 36 36 35 36

Reference adhesive 18.1 37 31 29 27 10 59808

Example 5:

In the laboratory, a carrier-free one-component adhesive was prepared without heating by mixing B-starch and unmodified wheat starch in different proportions with cold water. Sodium hydroxide and borax were further mixed into the slurries. The B-starch used contained 7.0% by weight of protein and 5.0% by weight of pentosans. B-starch grains were 2.5% larger than 10 μm and 86% larger in the size range 2 to 6 μm, and unmodified wheat starch contained 0.5% by weight protein and 0.2% by weight pentosan. Stein-Hall viscosity and gelatinization temperatures were determined from the adhesive mixtures. The compositions of the adhesive mixtures and the results obtained are shown in the following table:

No Starch mixture Visco- Gelati- B-starch- Wheat- Prote- Pento- NaOH Borax-agitation- starch- starch iins obtained si heat- _ (parts by weight) _ (% of mixture) (% of mixture) (s) _status (° C) 1 20 80 1.8 1, 2 1, 0 1, 0 1 8.5 61 2 40 60 3.1 2.1 1.0 1.0 21.5 62 3 60 40 4.4 3.1 1.0 1.0 33 63 4 60 40 4.4 3.1 1.2 1.2 35 59 5 80 20 5.7 4.0 1.1 1.1 54 61

Based on the analysis results, all mixed sludges are suitable as corrugated board adhesives.

Claims (2)

A combination of substances, mainly containing unmodified starch, suitable for the production of corrugated board, which, when slurried in water, binds considerably more water than conventional unmodified starch in the same concentration of water slurry and has improved durability and viscosity stability under stress compared to corrugated board adhesives made from conventional unmodified starch in the same way, characterized in that it consists of 0 to 90% by weight of conventional unmodified starch and 100 to 10% by weight of a mixture consisting of unmodified wheat starch, having a grain size distribution of: not more than 5% greater than 10 μπι and not less than 80% between 2 and 6 μπι, and consisting, in addition to the said starch, of 1 to 8% by weight of wheat pentosans and 1 to 10% by weight of wheat proteins, calculated on the dry matter of the mixture. A combination of substances according to claim 1, characterized in that the starch contained therein is in the form of non-gelatinized grains. 1. For the preparation of wellpapplim LAMP ämneskombination containing glasses principally composed omodifierad Stärkelse, vilken ämneskombination uppslammad binder in water betydligt of water in more dirt than the I vattenuppslamning of field of konventionell omodifierad Stärkelse Science de wellpapplimmen thereof prepared is provided with a förbättrad styrka Science viskositetsbeständighet under upprepade upphettnings-nedkylnings-Cykler 10 ... 50 ° C and under the mechanical pressure of the conventional starch of the starch is well within the limits of the well-being of the paperboard, with a maximum of 0 ... 90% by weight of the conventional starch and 100% by weight en blandning, som bestär av omodifierad vätestärkelse rod fördelning enligt kornstorleken är: högst 5% över 10 um oct ätminstone 80% Melian 2 ... 6 um, och som förutom nämnda stärkelse till 1 ... 8 vikt-% bestär av vetets pentosaner och till 1 ... 10 vikt-% av vetets proteiner beräknat pä blandningens torrsubstans. 2. Ämneskombination enligt patentkravet 1, kännetecknad därav, att den däri ingäende stärkelsen är i form av ogela-tinerade Korn.