SE443992B - WATER-ADHESIVE CONTAINER INCLUDING A BERARDLE OF MOLECULATED DISPERSED STARCH AND PART OF OGELATINIZED STARCH - Google Patents

Description

IUUUUUU V 10 15 20 25 30 35 2 due to the high speed of the machines, the adhesive must be able to give 'immediate bonding' when heat and pressure are applied.

Starch-based adhesives for corrugated cardboard are traditionally produced according to the Stein Kall process. This is a system in which the main part of the adhesive consists of whole unmodified maize starch grains, which are suspended in water with about 20% solids, the grains being kept in rotation by means of a carrier part, which consists of cooked starch paste. The adhesive was prepared in principle by boiling the carrier part in an open tank with fresh steam and this is carried out conventionally in batches. Later developed methods have, however, led to a continuous production of the adhesive by using so-called jet cooker under atmospheric pressure for the production of the carrier part.

This is then added to a second tank containing the uncooked starch slurry (not the carrier moiety).

A typical Stein Hall adhesive has the following properties: Gelatinization temperature - 62 ° C to 65 ° C stein naii viscosity via 3s ° - One-sided corrugated cardboard, 30 to 35 seconds Bnwell cardboard 45 to 55 seconds Solid material - 20% commercial basis (c / b) pa - 11,3 tili 12 Ratio of carrier starch to (non-carrier) starch approx. 1: S, 5.

Such adhesives have various disadvantages: a) the amount of carrier starch (gelatinized starch) determines the initial tackiness of the adhesive and this and the solids content of the adhesive determine the speed at which the cardboard making machine can be run. It is difficult to achieve a Stein Hall adhesive, which has acceptable initial tack and acceptable solids content without also obtaining an unacceptably high viscosity. Efforts to eliminate these disadvantages have previously involved the use of chemically diluted starches which do not give rise to gelatinized solutions with lower viscosity, but these types of starches are significantly more, .smsssass fififi ss§ï »-» Jil-Ä f * 10 15 20 25 30 35 / öuo00U ° 0 3 more expensive than unmodified starch, and cardboard adhesives must necessarily be fairly inexpensive products. b) The viscosity stability of the adhesive is poor due to the tendency of the gelatinized starch to retrograde or harden as it takes shape. cl As the board product must be water-resistant, bridging resins are usually added to the adhesive. The heat used to gelatinize the carrier moiety also affects the reaction between the starch set and the bridging resin to form a water-resistant bond. However, a conventional Stein Hall adhesive has poor reactivity with bridging resins. An object of the present invention is to eliminate the stated disadvantages of conventional adhesives and to provide a continuous method by which improved adhesive sites can be made.

One aspect of the present invention therefore relates to a starch-based aqueous adhesive having a solids content of 10-40 weight, a Stein-Hall viscosity at 35 ° C of 20-100 s, and which, in a weight ratio of from 1 : 2 to 1: 8, al includes a carrier moiety comprising gelatinized starch. and b) a non-carrier starch comprising unelatinized starch having a gelatinization temperature in the adhesive of 55-75 ° C, characterized in that the carrier moiety comprises gelatinized molecularly dispersed starch having a viscosity of not more than 1000 cP, measured at a 10% solids content and a temperature of 50 ° C.

Unless otherwise stated, the solids content is expressed on a commercial basis (c / b), which means the content of commercially available starch and other solids in relation to water. commercially available types of atherosclerosis contain a small valley, normally about 121, of water, so that an adhesive with 20% c / b solids roughly corresponds to an adhesive with 18! d / b (dry basis) solid material. s É $ V ~; Nv '”'.; * fi1 '~“' - lry.¿_a-, vj * íj ~ j Jí fl j '.' . V w -fifl f «~ -s = wåra? 1.; x; .- t.§f, i ...» en e, f! Crude starch comprises molecular bundles which are held together by hydrogen bonds. conventional gelatinization, for example by treatment with steam at not more than 100 ° C, loosens and breaks up these bundles partially but not completely. In the case of molecularly dispersed starch of the type used in the carrier part of adhesives according to the present invention, the bundles are substantially completely broken up and the individual starch molecules are substantially separated. A molecular dispersion of starch can be achieved by gelatinization under severe conditions, such as by using excess vapor and temperatures above 100 ° C, as will be more fully described in the following. Molecularly dispersed starches are characterized in that they have a viscosity not exceeding 1000 cP measured at a solids content of 10% and a temperature of 50 ° C and normally in the order of 250 cP. Conventionally gelatinized starch under these conditions has a viscosity which clearly exceeds 1000 cP.

It is preferred to use unmodified starches for the production of adhesives according to the present invention. Modified starches, such as etherified or esterified starches, can be used, but since they are normally more expensive than ordinary starch and because little or no benefit is normally obtained from using them, these starches are not preferred.

Partially oxidized or acid or enzyme hydrolysed starches can be used and this leads to a lower viscosity during gelatinization. However, unless they are also molecularly dispersed, they do not have the necessary viscosity stability and are not suitable for use in the present invention. Although arbitrary cereal starches or vegetable starches can in principle be used in the adhesive and in the method according to the invention, corn or wheat starch is usually used for adhesive for corrugated board. f ».m vw ... act-vi., zaq fl vés fi lrmfwaqnewßszva; wcsaâsxåânä fl szr - ~, y,, .z J. vs; =.« * sš. ^ j * fl l ^ axå.-r; f »_ '.- A number of high viscosity water-dispersible polyhydroxy polymeric materials can replace up to half of the starch used in the support portion of the adhesive. Examples are cellulose derivatives such as sodium carboxymethylcellulose, polyvinyl alcohols and hydrolyzed polyvinyl acetates and polyvinylpyrrolidone.

As previously stated, the content of solids and the ratio are carrier: non-carrier in a certain ratio. The types of adhesives preferred according to the invention are prepared so that they fall within an area in a diagram, where the solids content is plotted against the weight ratio of carrier part to non-carrier part, which is limited by the four points: Solids content 10 20 35 35 1: 2 1: 2 1: 6 1: 8 This area is shown graphically in Fig. 1 of the accompanying drawings.

Due to the lower viscosity of the molecularly dispersed carrier starch, adhesive compositions of the present invention with a given solids content and viscosity have a lower carrier zipper carrier ratio (ie, contain more carriers) than conventional Stein Hall adhesives. This property can be taken advantage of in two ways.

If the solids content is kept unchanged, the adhesive will have a better initial tack than the Stein Hall adhesive. Under these circumstances, the adhesive preferably has a ratio of carrier zinc carrier from 1: 2, 5-1: 4.5, especially 1: 3-1: 4, and a solids content of 15-25 weight.

Alternatively, the solids content can be increased without any fatal loss of initial tack to form a drier adhesive, thereby enabling a machine for making corrugated board to work faster than when using a Stein Hall adhesive. Under these circumstances, the adhesive suitably has a carrier: non-carrier ratio of 1: 4-1: 6 and a solids content of 20-30% by weight. sin »en" i .g _ .f. -sh »inf.-_.« meets-ß. "-n, v,. The gelatinization temperature of the non-carrier part of the starch in the adhesive suitably varies between 60 ° C and 70 ° C, and in particular between 63 and 66 ° C. If this temperature is too low, premature gelatinization of the starch and thickening of the adhesive may occur. If the temperature is too high, an excessive amount of heat may be required for the adhesive to be fully effective.

The gelatinization temperature is in principle determined by the content of sodium hydroxide in the adhesive. Use of up to S, preferably from 2-3.5, weight! Based on the weight of the starch, sodium hydroxide is conventional and also suitable in the present invention.

Borax is also conventionally used in Stein Hall adhesives to stabilize viscosity and increase tack. In the present adhesive up to 5% borax is used and suitably an amount of 0.75-3.25 weight is used! of the weight of the starch. When a waterproof bond is required, crosslinking agents or preformed resins are incorporated into the adhesive according to conventional practice. Other additives may also be included in accordance with conventional practice.

According to another aspect, the present invention relates to a process for preparing a starch-based aqueous adhesive, which process is characterized in that a) a carrier part of gelatinized, molecularly dispersed starch having a solids content of 3- 40% by weight and having a viscosity not exceeding 1000 cP, measured at a solids content of 10 8 and a temperature of 50 ° C, by boiling a starch slurry with a jet cooker operating at a temperature of 110 ° C 170 ° C with at least 1.1 times the amount of steam necessary to heat the slurry to the required temperature, b) mixing the carrier part with a slurry of non-galvanized starch with a solids content of 10-40 wt! in relative proportion to a total solids content of 10-40 weight! and a weight ratio of gelatinizedzogelatinized starch from 1: 2 to 1: 8, a, _ »sletse; ¿a% § ¥ iæa¿wammsä¿ßaa. @. f» ~ ¿. ~ fl. # awaæaäawH. so. (c) alkali is added to the resulting mixture in an amount of up to 5% by weight based on the weight of the starch, so that the gelatinization temperature of the ungelatinized starch amounts to 55 -75 ° C.

An important feature of the method according to the invention is the use of a jet cooker with excess steam at a pressure above atmospheric pressure to boil the carrier part of the starch. Such boiling is not new and has been described, for example, in U.S. Pat. No. 3,133,836, but it has not previously been used to make the carrier moiety in starch-based adhesives. A jet cooker works with very high shear conditions and these become even more severe when using overpressure, boiling temperatures from 110-17o ° c, preferably from 13o ° c: 111 1so ° c, and excess steam. If the boiling temperature is predetermined, the amount of steam which is exactly sufficient to heat the starch slurry to this temperature and which is thereby completely condensed can be easily calculated. According to the present invention, excess ash is used compared to that required to heat the slurry and the excess passes unconcentrated through the digester. The amount of steam used should be at least 1.1 times the amount required to heat the slurry to boiling temperature, preferably from 1.25-5, especially from 1.5-3 times the amount required. The use of strict conditions leads to a much more complete breakdown of the starch grains than in the usual gelatinization process. Starch, which has been subjected to this treatment, is present in a molecularly dispersed state.

The viscosity of the starch paste obtained (at a given solids content) depends on the boiling time and boiling temperature and on the amount of excess steam used, but it is always substantially less than the viscosity of a starch solution which gelatinizes under normal conditions. The viscosity of a starch, gelatinized in a jet cooker at a temperature of at least 110 ° C and at least 1.1 times the required amount of steam (measured at 10% solids and a temperature of ° c) a: name determined sj more than 1ooo ev, foreeraaesvln from 100-S00 cP and especially from 150-200 cP. A normally gelatinized starch solution, on the other hand, would have a viscosity of 6-7000 cP under the same conditions. The solids content of the finished adhesive amounts to 10-40 weight c / b, preferably from 1-5 c / b, eg 20% c / b, and is selected with regard to viscosity, the strength of the incipient stickiness and the final adhesive strength. An adhesive with a desired solids content (say 20% c / b) can be obtained by mixing suitable proportions of 20% solids c / b carrier moiety and 20% solids c / b non-carrier moiety; or by mixing a more dilute carrier moiety with a more concentrated non-carrier moiety; or by mixing a more concentrated carrier moiety with a more dilute non-carrier moiety. The content of the solid part of the carrier part can vary from 3-40, preferably from 5-35%, in particular 10-20% by weight! c / b. over 20% solids, the gelatinized starch solution tends to gel when allowed to stand, which is a disadvantage but not an insoluble problem. As a jet cocker is allowed to operate at solids levels below 10%, there are some difficulties in achieving the desired temperature in the final adhesive mixture. As for the non-carrier part of the starch, the slurry, which contains l0-40 weight! solid material c / b is easy to handle. The solids content of the ichw carrier slurry is selected relative to the solids content of the carrier solution and the proportions in which the two are to be mixed together to produce a final adhesive composition with the desired solids content. A The non-stretcher starch slurry is normally used at room temperature. However, the carrier part has just passed through a jet cocker at high temperature. If the carrier part and the non-carrier part are simply mixed together, ffw- I; »:. _ ..,. ¿, VTH, 10 15 20 25 30 35 l flflfi VVü 'U 9 it is likely that premature gelatinization of the non-carrier starch takes place. It is therefore a normal 'measure to ensure that the temperature of the mixture does not rise above 40 ° C. For this purpose, the carrier part of the starch does not normally need to be cooled; the temperature to which it needs to cool depends on the relative volumes of the two parts and can be easily calculated for the individual case.

The carrier part and the non-carrier part are mixed together in such proportions that an adhesive composition with the desired viscosity is obtained. Since the viscosity of the carrier moiety is significantly less than the viscosity of gelatinized starches previously used as carriers, conventional concentrations are about 20% by weight! The c / b ratio of carrier zinc-carrier is necessarily less than the conventional weight ratio 1: 5.5 and in practice it has been found to be in the range 1: 2, S1: 4, S, in particular 1: 3.0-1: 4.0. calculated by weight. At ratios above 1: 4.0, it has been found that the viscosity of the adhesive composition is too low to be suitable. At conditions below 1: 3.0, the present adhesive compositions have too high a viscosity, which can only be lowered to an acceptable level by very high dilution with water. It has been found that a cleaver composition with 20% c / b solids and having a weight ratio of carrier zinc carrier of 1: 3.5 gives adhesive compositions of desired viscosity, or compositions which can be easily diluted with a small amount of water to the desired viscosity. . However, it could be expected that the use of different cooking conditions or of different levels of solids would give different preferred ratios to carriers. The elister compositions of the invention have a preferred Stein Hall viscosity via 3s ° c from zs-ss s, faretraaesvis from za-as s for adhesive compositions for single-sided corrugated board and from 45-55 s for compositions for enwelled board.

As previously stated, the adhesive compositions of the present invention may advantageously contain sodium hydroxide so as not to lower the gelatinization temperature of the carrier starch. This sodium hydroxide suitably adds the carrier part of the ether clay and can be added to the slurry of the crude starch which is fed to the jet (cocker). Alternatively, the sodium hydroxide may be added to the non-carrier moiety or to a mixture of the carrier moiety and the non-carrier moiety. The sodium hydroxide can advantageously distribute: between a carrier and a non-carrier.

As previously stated, the adhesive compositions of the invention may advantageously contain borax. Boron: may conveniently be added to the non-carrier portion of the starch. Alternatively, it may be added during the final mixing of the carrier moiety and non-carrier moiety. An addition of the entire amount of borax in the starch slurry which is fed to the digester under pressure (the pressurized jet cooker) can give rise to the viscosity problems. It may be advantageous to have a single slurry of raw stock, which may contain some or all of the the amount of sodium hydroxide and borax desired in the final adhesive composition and to divide this slurry into two streams, one of which is passed through the digester to gelatinize the starch, and then to remix the two streams and to add in this step any additional sodium hydroxide or borax , which may be desirable.

The composition and method of the invention provide the following advantages over the conventional Stein Hall adhesive and the method of making it: 1) A higher carrier to non-carrier ratio is possible without having to resort to expensive modified starch types with low efficacy. The carrier to non-carrier 1: 2.5-1: 4.5 can be obtained without the usual viscosity increase associated with unmodified carrier starch, so gelatinized on a conventional basis. .._...-. = í ,, ~ * 1ë -?;:; .-: I 511.2 ... _; _ 10 15 20 25 30 35 11 2) The adhesive has an initial tack with higher strength during the early formation of the bond. 3) Alternatively, a higher content of solid material is possible with the same carrier-carrier ratio without obtaining an impossibly high viscosity, which leads to the machines for producing corrugated board being able to run faster. 4) The carrier moiety, which is completely dispersed at the monomolecular level, has similar viscosity stability than conventionally produced starch and the final adhesive is less susceptible to shear forces. 5) The final mixture has higher adhesion depending on the manner in which the carrier is dispersed and a higher content of carrier. 6) The higher carrier ratio gives an adhesive, which reacts better with bridging resins to a water-resistant bond. 7) The method allows an adhesive for corrugated cardboard to be manufactured continuously. In Examples 1 and 2 below, the following general method was used. Two separate aqueous corn starch slurries were prepared, one of which was a carrier portion and the other a non-carrier portion. The sodium hydroxide was distributed pro rata between the slurries with carrier and without carrier: the whole amount of borax was added to the slurry avicked fi kare. The carrier slurry was boiled under overpressure in a jet cooker under the following conditions: Ang pressure 517-551 kPa (overpressure) Boiling temperature 482 ° 155 ° -S24 kPa (gauge pressure) The carrier hash flow rate of 3.1 dm / min The resulting carrier moiety had a viscosity (measured at 10 wt! Solids and 50 ° C) of 150-200 cP and mixed with the non-carrier moiety to the desired adhesive composition. . t .i fièï? Ifeff Yes? In this experiment the content of solids in the cleaver composition was kept constant at 20% by weight / c and the effect of varying the ratio (carrier excipient) was not limited to 735 "e. å. s.,", «.«. 10 15 12 Bxggggl l. The results are shown in Table 1 below.The temperatures of the non-carrier parts Oßh and for the final adhesive are included in this table, it should be noted that in three cases the temperature of the finished adhesive was higher than 40 ° C, this does not appear to have been harmful under the conditions used in the experiment (small scale), but it would be unsuitable for commercial operation.The viscosity of the adhesive in a carrier ratio: non-carrier of 1: 3 was rather high but it could have been lowered either by modifying the boiling conditions of the carrier or by diluting the final adhesive. : vw 3 :. ._ Aäeâ _ øåøxuaun åu nu nnå ”xenon .S332. <0 a. äá” vusårš fi huäz n.- | m.- za _ n \ u nn .ø ~ | m.- .n \ u now fl n fi uuuu fl annu u fi nm _ \ uonoåo usuøuunauu-uc fi uon fl c fi uø fl oo "øøunuc fi ßvaßa: Eâuøn o .. ... nu _ owe øe fl on fl oø fi øn | 1 »nav uonn am» uuu «noun«> | u ~ o «wxoøu U oc? 2 .. .S Ne nn ~ n nu om nu 3 A8 uonn 3 »uou fl uox-Én fi nn ä: nn S. 3 3 å en 3 S å 2 8%» aunägaß 393.2 .. -333- 3 un nu fl n on .fl u ow ß fl N fl nu o fl nuøv u fl ucuøàlou ccønuosuaun duxoxo 6 en nu om om en ß fi as No no cs .nuov V uøunuonßuu: nunnan ou nu ou ou om om ow ou on ^ A \ o av ou fl oxunuø usosu M fi owu ON ~. ~ N. ~ no ow ON ON ^ ø \ u av _ Guiana M fl cwuøuni annu u fl ø ¶mn ”~ nn" ~ ena nu fl wu fl fi øn fl øuunun uxøxouøunuanv øvcu fifi wsunm uomøšzäuu nao fi nïa nåa 522.1 “nïa 522.1. aocm fl »mamma Bon uxøuua: en UIUAQGIÜ ~ fifi onwu f§ ~ 4 ..» ,, ~ _4 _.- la 14 Bxeggel 2 In this experiment, the adhesive content of solid material was kept at 20! c / b, _pch the ratio of carrier carrier was maintained at l The effect of varying the sodium hydride content and borax content of the adhesive was determined and the results are shown in Table 2 below.In this table, adhesives containing 3.75% and 5% borax were not usable. contained 1.58, 1.0l and 0.58 sodium hydroxide, were rather highly viscous but 10 could have been improved by splitting. unfsf-.Léw fl ië.; f «æem = ï, tizmv.i * ..; fi ;: ~ '. and 0.0. - - 0.0. 0.0. - 0.2 S ... 5 00.033 0.00 3 0200 | 0020 - 0303 002 0030 0030 0030 800 .0002800300002-0000 .. 0.0 0.0. 0.3 0 ... 08 000.0 ... 0 .: 0.0. 0.0. _. 000 00 .. 000. 00. 003.100 000 03 00. .03 0000 3 »0ßï0å0ï00å00â0, .00 007 00. .0 000003 0 .. 00 00 .s 0000 00» 0.:.0..:>- .. ~ .. 0030 0.0 0.0 0.0 0.0 0.0 0.0 00.0 0.0 00 .. 0 02.8.0000 00 00.80 0.0 .0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 00:30 .... 0 .. 000 .. øcuocomunuucøucoznneuon ... ua umonz 200020 u: ... anwa øwcma: ... au uxouwø non N: anna_ “faan vw _ \ 10 15 20 25 30 35 16 Example 3 Fig. 2 of the drawing shows a diagram - _ for a plant operating according to the method according to the invention. . The levels of sodium hydroxide and borax refer to weight calculated on c / b starch.

In Fig. 2, 10 denotes a slurry tank, which is filled with: water via line 12; sodium hydroxide via line 14; borax via line 16; and corn starch grains via line l8. The slurry tank contains 20 weights! solid c / b, 2.58 sodium hydroxide and 0.1 wt! borax. The slurry is continuously withdrawn from the bottom of the tank 10 via line 20 and divided into two separate streams, 22% in line 22 and 78% in line 24 (ie a ratio of 1: 3, S). The slurry in line 22 passes to a jet cooker 26, which is commercially available under the trademark Nemo Junior, where it is boiled as in Examples 1 and 2 with excess steam, which is supplied via line 28 and then fed to the holding tank 30. The slurry stream in line 24 is passed to another holding tank 32, where it is mixed with another 3 weights! borax from line 33 (to 2.5% by weight in the final composition).

The carrier part of the composition from tank 30 and the non-carrier part from tank 32 are fed to an in-line mixer 34, where they are mixed thoroughly and then to a storage tank 36. It may be advantageous at least during the start-up phase of the system and possibly throughout the process , recycle a portion of the adhesive composition from the storage tank 36 via line 38 to the mixer 34. The resulting adhesive composition has a Stein Hall viscosity at 35 ° C of 41-45 s. It is removed as required via line 40 for use in a machine for manufacture of corrugated board or via line 42 for dilution before use in a machine for producing single-sided corrugated board if this is possible.

The properties of the adhesive produced in the pilot experiments with the specified equipment are given in Table 3, in which the properties of a conventional Stein Hall adhesive are also given for comparative purposes. It can be seen that the reproducibility is very good and that the given properties satisfactorily correspond to the properties of a conventional Stein Hall adhesive. It should be noted that Table 3 is intended to show that an adhesive for corrugated board with commercially acceptable properties can be produced continuously; the table is not intended to illustrate the superiority of the present adhesive compositions over conventional compositions. I 'ÉI J', _, _, fwf ".,. '« F' ~. ~ - = "” "_; ._- 'fs fl x” JTH _' “'j_ * ïf'ï'“ "'5 "~ '" É4 "” f "" V * - ~ = ...' * V ', fgf, », _ - ~ - \ ~.».', I - - fw "F" 'O ».

II .v '1_ r' ~. «- * ~“ ° -, .., f .w-; fl "v“ "- Ä; - -" '. -, ._ C' .-, - <* am .v fw 'K "å” -J ru:.; _ "_;., .._.,' ~, __- * g, - = ;;: -., ~." \.: _ ', - ,, 'Ä .-,. ; ~. _,. n. _ ~ -. n. -. _ «_ _, - 4. ,, ~ - -«. _ Wine. -, «.;,»., -EUw-.o -. ,, «M -w-» w> -_ v _. fw. . «_ ~ <». ,. , __ ,, '- .'-._ ¿,., __ ¿-; _ l | ... and stl-ma; now 'If "~' v .www ßå fi ßnf n. .JJ.. i u. ... ,,, ._....._ w, ï ..____, _. fl 8 ~ 8 ~ | 2 ~ 8 ~ 83 u3 fi. ° ..,. 3> .. 33¶.8 .. n. ~ «Ne a we ne AV» u »~ qøx.«> »« ~ N =: dann øo fl ucunaøn ua> n uunulououn uuu fi. cowunuunou uo> a uoucucoalox .uonn vw »A en man o- n mø« oßn Amuv uou fi- osu «> | æ ~ u ~ uxoøun. oc? oc? u oo? oc? ^ &» uäåuåï fifl nm Sån ß 33.3 uauaàuuåou auøocu fifi ou. unuuou un: sin uøunucäox .noen 3 »n eu uuouw fl uanum ___:., ... ß 0.3 0.2 0.3 _. nn ~ n.ø ~ ou ~ ~ .ø« ~. ~ H Any fl uwuøunø »now u fl n nø \ nø. nø \ «o oø \ <ø oø \ no nø \« o Aoov uaunuøgaøuuuc fi uonwuo fl ou oo ~ a- o fl w øo ~ ø- Away uonn vu »uu» «øox @«> | v ~ o «uxoo ~ n ce ne ~ <ne me ^ -V oonn ø «> uuu« @ox »«> | -ø = nwoum uunm fl xu flfi øu awøum u-uco «uøo> nas uounm fi xmanqpnm a> u» øuu «~ u uonuøw fi xnxmøunu unu uvum fl wawuuuuuuuuuuu: Examples 4 and 5 are comparative examples, which are intended to show the difference in the ratio of carrier ethic carrier to carrier. , which is required to produce adhesives with two different levels of solid matter al, using an approach according to the present invention and an approach according to the conventional Stein Ball method.

Example gel 4 20% solids 1. Stein Hall technique (standard) 18 g of corn starch was slurried in 80 g of water and heated to 70 ° C. This slurry was added with 3.2 g of sodium hydroxide dissolved in 8 g of water. The mixture was stirred and stirred at 100 ° C for 15 minutes, after which 100 g of cold water was added.

This cooked starch paste (carrier) was added to a slurry containing 88 g of corn starch, 260 g of water and 3.2 g of powdered borax and the whole was shaken for 15 minutes.

Adhesive properties: Stein Hall viscosity Solid material - aa s via 2o ° c = 20.1! Commercial basis Carrier starch ratio: boron and starch I 1: 4.9 2. Technology according to the invention A slurry containing 83.5 parts of water, 13.2 parts of corn starch and 3.3 parts of 10% sodium hydroxide solution was treated via a 'jet heat' at 150 ° C under a pressure of 5.5 atm. The starch paste formed had a solids content of ll after condensation of steam! on a commercial basis. 180 g of this carrier paste was added to a slurry containing 230 g of water, 70 g of corn starch, 1.7 g of sodium hydroxide and 2.2 g of powdered borax, and the whole was shaken for 10 minutes.

Lšivláwïr fi Üëvt '.då “ef% _ å? tå t: i .¿: 3. '= §: ï "~ *“' ~. “'§ *?" * vi -www-kg .if-I fi: Jf-fjt »vâx. vv-íi; , 'altan Affaaae-sèikav; a _ -ff fïÉà- * vflïfènàßšfífaw-.esfwíâm L, e, m:; i 78Uóö8b ° b 10 15 20 25 30 35 20 Properties of the molding: Stone Hall viscosity Solid material - 41 s via zo ° c = 19.4! commercial basis Ratio starch ratio: boron starch I l: 3.5 Example gel 5 25% solids 1. Stein Hall technology gstandard) 18 g of corn starch was slurried in -80 g of water and heated to 70 ° C. This slurry was added with 3.9 g of sodium hydroxide dissolved in 10 g of water. The mixture was stirred and heated at 100 DEG C. for 1 minute, then cold water was added.

This cooked starch paste (carrier) was added to a slurry containing 112 g of corn starch, 220 g of water and 3.9 g of powdered borax and the whole was stirred for 15 minutes.

Adhesive properties: Stein Hall viscosity Solid content - so s at 2oPc - 25.28 commercial basis Ratio of carrier-borne starch 2. Technology according to the invention A slurry containing 83.5 parts of water, 13.2 parts of corn starch and 3.3 parts 10% sodium hydroxide solution were treated via a jet heater at 150 ° C at a vapor pressure of 5.5 atm. The formed starch paste had a solids content of ll after steam condensation! on a commercial basis. 180 g of this carrier paste were added to a slurry containing 210 g of water, 100 g of corn starch, 2.5 g of sodium hydroxide and 3.0 g of powdered borax, and the whole was stirred for 10 minutes.

I l: 6,2 @ «enwweswwew” ** wm “*“ “fl r ~ * wmw flfl wH ~ i¿» ~ f., \, I_naz fifififlfi h¿e fi a fi aææ% æia »i @@ se ._af ', ='" -. -y ..:..;, - ,, ~ ',, 2,.: _ - .. w. _,, _ »J ëfstavwanintfwi-.innhšäf tm» QR. m: <1. kmflæ -. * is ~. »Zí; r -, _-. Fl æ ~ fi ißavrffzem-.uaëaïirv 2. ', .-; ..« vuøuu0 “0 21 Klisteregenskapers scen aan-viskositet - sz a via 2o ° c Halt solid material an 2S, 3 \ kosmet- siell basis S Relationship carrierstrrkelsøzburen _ starch ~ 1: 5,1 »'ä:.' WY f fä * aååqéšßiëgi-ë fl kfl; .aæiiem ¥ hfm. '. f. ~. \: c.-zæal &i;:æ:,; ~ ¿'.¿ ^ § «"; -' a *. .. '. ".. ' , »,«

Claims (11)

ílâ- PASENTKRAV Starch-based aqueous adhesive, having a solids content of 10-40 wt., A Stein- -fl all-viscosity at 35 ° C of 20-100 s, and which, in a weight ratio of from 1: 2 to 1 : 8, comprises a) a barrel portion comprising gelatinized starch, and b) a non-carrier portion comprising ungelatinized starch having a gelatinization temperature in the adhesive of ss-1s ° c, characterized in that the carrier portion comprises grips gelatinised, molecularly dispersed starch having a viscosity not exceeding 1000 cP, measured at a solids content of 10 och and a temperature of 50 ° C 2. An adhesive according to claim 1, characterized in that the solids content and the carrier ratio of carrier zipper carrier fall within a range in a linear diagram of the solids content to the carrier ratio of carrier zipper carrier, which range is limited by the four points: 20 content solid material 10 20 35 35 Weight ratio 1: 2 1: 2 1: 6 1: 8. Adhesive according to Claim 1 or 2, characterized in that it has a solids content of 15-25 volts. 25 Adhesive according to any one of claims 1-3, k 8 n - n e t e c k n a t due to the fact that it has a weight ratio of carrier zipper carrier of from 1: 2.5 to 1: 4.5. Adhesive according to any one of claims 1-4, characterized in that the carrier part comprises gelatinized, molecularly dispersed unmodified corn or wheat starch. Adhesive according to one of Claims 1 to 5, characterized in that the molecularly dispersed starch has a viscosity of from 100 to 500 cP, measured »than 1.9. y fl n: Vgfls ¿-,;. ¥. _. _ 1 »* Åíå fi š * nk-Éålååšfzš fl nßmm-: fåšréïfšä fl a / * Ln. kf, v; 'å. 10 15 20 25 30 35 l0Uä0Ö0'0 33 at a solids content of 10! at a temperature of 50 ° C. 7. An adhesive according to any one of claims 1 to 6, characterized in that the non-carrier moiety comprises ungelatinized, unmodified corn or wheat starch with a gelatinization temperature in the adhesive of 63-ss ° c. Adhesive according to one of Claims 1 to 7, characterized in that it also contains 2-3.5% by weight! sodium hydroxide and 0.75-3.25 wt borax, both based on the weight of the starch. 9. A method of preparing a starch-based aqueous adhesive according to any one of claims 1-8, characterized in that a) a carrier portion of gelatinized, molecularly dispersed starch having a solids content of 3- 40 weight! and having a viscosity not exceeding 1000 CP, measured at a solids content of 10! and a temperature of 50 ° C, by boiling a starch slurry with a jet cooker operating at a temperature of 110-170 ° C with at least 1.1 times the amount of steam necessary to heat the slurry. to the required temperature, b) mixing the carrier part with a slurry of ungelatinized starch with a solids content of 10-40% by weight! in relative proportion to a total solids content of 10-40 weight! and a weight ratio gelatinized: ungelatinized starch from 1: 2 to 1: 8, c) alkali is added to the resulting mixture in an amount up to 5% by weight! calculated on the weight of the starch, so that the gelatinization temperature of the ungelatinized starch amounts to 55-75 ° b. 10. A method according to claim 9, characterized in that the cooker (-jet cooker) in step a) operates at a temperature of 130-155 ° C with 1.5-3 times the amount of steam necessary to heat the slurry to the required temperature. 11. ll. Set according to claim 9 or 10, k ä n n e - 'fl w- _' fl- “Éí- * Üfñv -«, <F * FÉ-w,: f- - _ _ *. * '' .q Q-a-w. '- -, «fl fff fl. s * mautšmmáfzmumwwâät fi ëaaeàvniwa fi steøtwätïgrm: we .: wfäks V; 7803886-6 No. characterized in that a single slurry of starch is prepared which optionally contains some or all of the sodium hydroxide and borax desired in the final adhesive, that this slurry be divided into two streams, one of which the non-carrier part and the other is passed through the digester (-jet cøøker) to form the carrier part, and the two streams are remixed, at which stage the additional sodium hydroxide or borax is added, which may be desirable. : å