HU176495B - Method for producing intermediates for paperboards and cardboards - Google Patents

Abstract

1536229 Sulphamate-modified aminoplast resins CASSELLA FARBWERKE MAINKUR AG 2 April 1976 [5 April 1975] 13449/76 Heading C3R [Also in Division D2] A condensation product dilutable in all proportions with water and curable under neutral or alkaline conditions is obtained by reaction of an aminoplast-forming organic nitrogen compound with formaldehyde and one or more water-soluble inorganic sulphamates in the molar ratio 1 : 2À5-7 : 0À1-1À5, at 80-120‹ C. and pH 7-11 until the viscosity of a 50 wt. per cent aqueous solution is at least 300 DIN seconds and of a 20 wt. per cent aqueous solution is 120-300 DIN seconds (4 mm. DIN flow cup, 20‹ C.). In Example 1 melamine, 39% formalin and sodium sulphamate are heated in 1 : 3 : 0À6 or 0À3, 1 : 6 : 0À1 or 0À1 or 1:2À5: 1À5 molar ratio at 90‹ C. and pH 10-11 for 2-4 hours. In Examples 2-4 solutions containing 2À5-10 wt. per cent of the products, alone or with 0À4 times as much polyvinyl alcohol, are applied to paper as sizes. The products may also be incorporated into paper pulp.

Description

The present invention relates to a process for the preparation of auxiliaries for improving the wet and dry strength and surface water resistance of paper and paper products, characterized in that they are present in a molar ratio of 1: 2.5 to 7: 0.1 to 1.5 at 80 to 120 ° C. Melamine, formaldehyde and an alkylsulfamate are condensed at pH 11 and the condensation is continued until the viscosity of the sample set at 50% dry matter at 20 ° C is up to 300 DIN sec (DIN standard: 53 211).

The auxiliary material of the present invention can be used to produce paper, cardboard, paperboard and webs having beneficial wet and dry strength and improved surface water resistance. The auxiliary material according to the invention is present in an amount of 0.5 to 5% by weight prior to forming the paper pulp or web or web between sizing and winding, or up to 35% relative to the paper or web, up to 35% by weight. —35% by weight, preferably

It may be added in the form of a 1 to 10% by weight solution, optionally mixed with another water-soluble product.

It is known, inter alia, from published German Patent Application No. 2,301,035 that sulfite modified melamine resins can be used to improve the strength properties of paper. It has also become known that these resins can be used to improve the wet and dry strength of the paper when applied to the surface of the paper, for example by gluing. Such a process offers a significant advantage over the long-established method of converting melamine resin to cationic by adding a significant amount of strong acid and leaving it active on the cellulose active in the pulp, since reducing the amount of acid advantageously affects the durability and strength of the doped paper. the possibility of wastewater generation is also greatly reduced. Experience has shown (see, for example, Wochenblatt für Papierfab. 17, 671/1973) that sulfite modified melamine resins by this method can only be used if the paper has a minimal aluminum sulfate content, since the resins harden only in the acidic medium. This property, however, again makes it more important for the acid-free industrial processing of the resins, since aluminum sulphate is particularly acidic and imparts adverse properties to paper. The ability of the known sulfite-modified melamine resins to be processed by gluing is further limited by the fact that only resins with relatively high condensation rates can be used effectively. However, this condition limits the amount that can be added and thus the strength enhancement properties that can be achieved, since a paper web traveling at a rapid rate of 25 cannot absorb enough of the viscous resin.

It can therefore be concluded that papermaking requires low viscosity excipients which can be applied to the paper surface and cure without the presence of acids or acid salts.

It is also known from published German patent application 2,241,158 that after drying with melamine-fermaldehyde resins, after drying on surface dressings, binders with insufficient water viscosity, e.g. can be converted to swelling or waterproof. However, the applications described for melamine-formaldehyde resins have the major disadvantage of providing nerh in sufficient amounts in an alkaline medium. Thus, the need for waterproofing agents for surface treatment of paper, even in the alkaline range, provides a good value up to about 11, since some compositions used to treat the surface of the paper are used in an alkaline medium. Thus, in this embodiment, they require hardness in the alkaline medium, while the viscosity of the excipient itself is not critical, since the pulp used for the surface treatment of the paper itself has a relatively high viscosity. Sulphite-modified melamine resins are known not to have the desired starch effect in an alkaline medium.

It has been found that existing practical requirements can be met and the drawbacks described can be avoided by using an auxiliary agent in the range of from 1: 2.5 to 7: 0.1 to improve the wet and dry strength and surface water resistance of paper, cardboard, cardboard and webs. - 1.5 molar ratio by condensation of an aminoplast former, formaldehyde and sulphartite at 80 to 120 ° C, pH 7 to 11, while the condensation is continued until the viscosity of the sample set at 50% resin is 4 The viscosity of the sample, adjusted to a minimum of 300 DIN sec and a 20% resin content, measured in a DIN DIN spout, increases to a maximum of 300 DIN sec. The aminoplast resins prepared in accordance with the present invention are infinitely miscible with water and can be stacked in an alkaline medium. For the preparation of the excipients according to the invention, a mixture of 75-10% by weight of melamine and 0-25% by weight of urea, dicyandiamide or gualate is used as the aminoplast former. According to a preferred embodiment of the invention only melanin is used as the aminoplast former. Suitable sulfamates for condensation are preferably sodium sulfamates. It is particularly advantageous to prepare the products according to the invention by condensing aminoplastics, formaldehyde and Sulfamate in a molar ratio of 1: 3.0 to 6: 0.3 to 0.8. Condensation can be carried out at temperatures between 80 and 100 ° C under technically simple conditions. The viscosity is the most important characteristic in determining the stiffness seal of the excipients of the present invention and is of particular importance in determining the chemical nature and the application conditions of the excipient. For example, in the case of paper surfactants, in many cases, it is advantageous to continue the condensation as long as the viscosity of the aqueous solution adjusted to 20% resin rises to at least 12 DIN sec measured at 20 ° C with a 4 mm DIN spout.

The present invention relates to a process for producing paper, board, cardboard and foil webs having improved wet and dry strength and improved surface water resistance by providing a water-miscible and air-cured condensation product produced in accordance with the invention for paper pulp, paper pulp or paper. up to 35% by weight between 0.5% and 35% by weight, preferably 1% by weight, of the web or web wrapping, or optionally mixed with other water-soluble products. In a particularly preferred embodiment, the application of the condensation product of the invention to the formed paper web by applying or prior to a gluing press or, in the case of cardboard lattice, to the paper webs in various situations is done by applying 0.5% to 35% by weight of the condensation product. preferably in the form of a 1 to 10% by weight solution, optionally mixed with water soluble products.

A particular advantage of the excipient according to the invention is that it can be applied to the surface of the paper web after the forming of the sheet and penetrated into the paper web so deeply that the effect on the wet strength is at least as good as the excipient. The advantage of this operation is; that the excipient can be utilized with a very good degree of backing and that the excipient is 100% incorporated into the paper; Thus, unlike the addition to the pulp, up to about 20% is not wasted with the screen. The auxiliary clay according to the invention can also be added to the pulp by adjusting the acid to a pH of 2 to 3 according to the prior art. Not only does the use of the excipient according to the invention show an increase in the wet tensile load of the paper and the like produced according to the invention, but surprisingly, the wet tensile load is greatly increased as the additive is increased without reaching a saturation state of 8%. see Example 1 diagram). In addition, the values of dry tear load and dry bursting pressure are extremely increased for the use of the Excipient according to the invention.

Particular advantages may be obtained when the bath according to the invention is combined with other water soluble binders, for example starch or polyviril alcohol, to a pH of from 5 to 11, and to achieve a defined wet strength, 50% of the excipient without replacement, heat would be expected to decrease the wet strength of the substrate. This also applies when the use of the water-retardant binder alone does not substantially improve wet strength. In addition, the dry strength achieved by the excipient of the invention can be significantly improved by the addition of certain water-soluble binders, such as medium viscosity polyvinyl alcohol. Finally, by combining the excipient of the present invention with such water-soluble binders, a significant improvement in dry strength and a reduction in the surface water sensitivity of the hand-held substrate can be achieved.

The percentages given in the following examples are always weight percentages.

Example 1

a) 1: 3: 0.6 molar ratio

1848 g (24 moles) of 39% formaldehyde were added with 20 ml of 2 N sodium hydroxide, 1440 g (4.8 moles) of 40% sodium sulfamate solution and 1008 g (8 moles) of melamine, followed by heating at 90 ° C and pH 10. at about 4 hours until the sample cooled to room temperature is no longer liquid. Water (3600 mL) was added and cooled. This results in a resin solution having a viscosity of 27% with a viscosity of 14 seconds (measured at 20 ° C in a 4 mm DIN spout).

b) 1: 3: 0.3 molar ratio

To 462 g (6 mol) of 39% formaldehyde were added 5 ml of 2N sodium hydroxide, 180 g (0.6 mol) of 40% sodium sulfamate solution and 252 g (2 mol) of melamine and the reaction mixture was stirred at pH 10 and 90 °. At C, it is condensed for about 4 hours until the sample cooled to room temperature is no longer liquid. Water (900 mL) was added and condensed again at 90 ° C for about 2 hours, while the sample taken was mixed with an equal volume of 3% sodium chloride solution at 20 ° C.

The product was cooled to room temperature and water (300 mL) was added. The resulting resin solution had a viscosity of 35 DIN sec and a resin content of 22%.

c) 1: 6: 0.2 molar ratio

To 924 g (12 moles) of 39% formaldehyde was added 7 ml of 2N sodium hydroxide, 120 g (0.4 moles) of 40% sodium sulfamate and 252 g (2 moles) of melamine. The reaction mixture was condensed at 90 ° C and pH 10 for about 2 hours until the sample taken was no longer liquid at room temperature. Water (1500 mL) was added, cooled, and adjusted to pH = 9 with 0.6 mL of 10N sodium hydroxide. The resulting 20% resin solution had a viscosity of 50 DIN sec.

d) 1: 6: 0.1 molar ratio

To a 39% formaldehyde solution (924 g, 12 mol) were added 10 ml of 2N sodium hydroxide, 900 ml of water, 60 g (0.2 mol) of 40% sodium sulfamate solution and 252 g (2 mol) of melamine, and the reaction mixture was stirred for 90 min. At <RTI ID = 0.0> C </RTI> and pH 10, the condensation is carried out for about 2 hours until the sample cooled to room temperature is no longer liquid. Water (1400 mL) was added and after cooling to pH 9 with 2N sodium hydroxide. The resulting 20% resin solution had a viscosity of 14 DIN sec.

ej 1: 2.5: 1.5 molar ratio

To 385 g (5 moles) of 39% formaldehyde were added 10 ml of 2N sodium hydroxide, 900 g (3 moles) of 40% sodium sulfamate solution and 252 g (2 moles) of melamine and condensed under reflux at pH 11 for about 4 hours. , while the sample cooled to room temperature is no longer liquid. Water (900 mL) was added and cooled. The resulting 20% resin solution had a viscosity of 20 DIN sec.

Example 2

Aqueous solutions of the condensation product prepared according to example la) with a dry matter content of 2.5, 5.0, 7.5 and 10% were applied to a paper press containing about 55 g / m ² and dried in a hot air drying oven at 140 ° C. The web has a dry matter content of about 95% upon winding after the stated residence time.

Carry out the following measurements on untreated paper for treated and comparative purposes:

1. Dry paper is stored for 24 hours at 20 ° C and 65% relative humidity, and the tensile load and burst pressure are measured longitudinally and transversely. In Table 1, each measured data is also referred to as burst pressure as longitudinal and transverse tensile loads.

2. The paper is kept in water for 24 hours at 20 ° C and 65% relative humidity for 20 hours at 20 ° C and the tear load on the wet paper is measured longitudinally and transversely. The measured data are shown in Table 1 as the longitudinal and transverse tensile loads II.

3. The paper is heated to 120 ° C for 10 minutes, then stored in water at 20 ° C for 1 hour, and the tensile load on the wet paper is measured longitudinally and transversely. The measured data are shown in Table 1 as the longitudinal and transverse tensile loads.

Table 1 provides a summary of the measured mechanical strength values of the paper, depending on the amount of auxiliary nut applied.

Table 1

Concentration of solution applied (%) ! - 2.5 5 7.5 10 PH of the solution applied - 8.6 8.8 8.9 9.3 G / m ² applied 0 0.61 1.16 1.75 2.36 material% dry quantity on paper - 0 1.12 2.14 3.22 4.35 Burst pressure kp / cm ² 0.8 0.92 1.05 1.13 1.21 tensile load I 4.15 5.9 6.5 6.9 7.3 longitudinally II 0.7 1.3 1.7 1.85 1.95 direction (kp) III 0.7 1.6 2.3 2.6 2.9 tensile load I 1.25 1.7 1.8 1.9 2.1 transversely (kp) II 0.15 0.3 0.45 0.5 0.55 III 0.15 0.45 0.6 0.8 0.85

If the aqueous solutions of the condensation products described in Example 1a are used instead of the aqueous solutions of Example 1a, the results obtained are comparable.

Example 3

Filter paper of type S + S No. 557 is treated with the solution prepared in Example 16 by dissolving 20 g in 1 liter of water and impregnating it. In addition, the solution is always adjusted to pH with sodium hydroxide or formic acid in order to determine the efficacy of the excipient at various pH values. After soaking, the paper samples were allowed to air-dry for a while, then dried on a steam-heated drying roller at 120 ° C to a residual moisture content of 2 to 3%, and finally matrixed at 20 ° C and 65% relative humidity for measurement. The amount of resin applied to the paper

0.48 gm ² . The following wet tensile load values were measured on the samples:

PH of solution Wet tensile load kg-bar)

62.28

72.50

92.43

112.05

The surprising result of the excipient according to the invention is that the measurement results decrease only slightly with increasing pH. This finding is particularly important since most of the solutions used by gz are in the? When applied in a glue press or in contact application equipment, due to its combination with other products, it must be rendered alkaline to ensure compatibility, viscosity or stability.

When using the condensation products described in Examples 1, 2 and 3 instead of the aqueous solutions of the condensation products obtained in Example 1, comparative results are obtained.

Example 4

Specific gravity paper weight about 55 g / m ² a

Treat as in Example 2 and apply the following solutions to the paper:

Solution I: Aqueous solutions of polyvinyl alcohol of medium viscosity (pH 5.7) containing 1.0, 2.0, 3/0, 4.0% solids.

II. Solution A: Aqueous solutions of the condensation products prepared according to Example la containing 2.5, 5.0, 7.5, 10.0% solids (pH 9.0-9.3).

III. solution: aqueous solutions of the medium viscosity polyvinyl alcohol described in solution I and the condensation product prepared according to example le, whereas polyvinyl alcohol (ratio of alcohol to the condensation product in each case is 2.5 and the total concentration of solutions (9.1-8, At pH 6) 3.5, 7.5, 10.5 and 14.

ARC. Solution A: The aqueous solution of the medium-viscosity polyvinyl alcohol described in solution I and the condensation product prepared according to Example Ia _. 0 and a total concentration of solutions (pH 8.2-8.0) of 2.0, 4.0, 6.0 and 8.0%.

The papers treated in this manner were dried according to the procedure of Example 2.

The treated papers were kept for 24 hours at 20 ° C and 65% relative humidity, and then for 1 hour in water at 20 ° C, and the wet paper was measured for tensile and transverse loading. In the accompanying diagrams 1 and 2, the results obtained are plotted against the nature of the applied solution and the amount applied, as well as the results of the untreated paper.

Abbreviations and symbols in Diagrams 1 and 2 have the following meaning:

NBL (kp) = intermittent load, wet, longitudinal

NBQ (kp) = tensile load, wet, transverse

M (gm ^_2 ) = amount of drug applied per weight of treated paper * = 1. solution of solution x = 11. solution measuring point □ = III. solution of measurement

O = IV. solution of measurement

As can be seen from the results of the measurement, hpgy is advantageously compatible with the inventive excipient polyvinyl alcohol. By using up to 50% of polyvipyl alcohol, which does not improve the wet strength per se, instead of the condensation product prepared in Example 1a, the increased resistance of the paper to water sometimes degrades. relative to the value exemplified by the condensation product of Example Jp alone.

Comparative example

a) Strips of wood-containing paper weighing about 60 g / m ^{2 are} treated with an adhesive press and treated with a 10% solids solution of the condensate product of the present invention. Is the amount of material applied one? the strips of paper are varied so that after drying the strips of paper in the safes with 140 ° C air, the measured wick layer is between 0.2 and 2.0 g / m ² .

b) For comparison, another paper is treated as described above, with the exception that a 10% solution of a commercially available sulfamate-free melamine resin is used instead of the resin of the invention.

Tissue sample obtained according to a) and bj ^e 120 C for a heat treatment after 10 minutes, UK. Subsequently, the paper samples were placed in water at 20 ° C for 1 hour and the wet tensile load was measured on the still wet paper.

Further pieces of the higher quality paper samples obtained above are stored at 20 ° C for 24 hours at a relative humidity of .65%, and the wet tensile load is measured both lengthwise and transversely.

The values of the pairs of values obtained for the measurements of length and transverse are calculated and plotted for the tensile load values (Figures 1 and 2). The figures show that the resins produced by the process of the invention exhibit a much better effect than the known excipients. Thus, for example, for a coating of 1 g / m ² , the wet load of the auxiliary paper produced by the process of the invention is about three to three times as high as the dry tear load value by 35% higher than that of the sulphamate mat resin improved paper.

Figures 2 and 3 show the values of the resins prepared according to the invention by the curve J.

2 is indicated by a dashed line.

Claims (5)

CLAIMS 1. A process for the preparation of a paper, cardboard, cardboard and web strip for improving the wet and dry strength »and surface water resistance, characterized in that it is present in a molar ratio of 1: 2.5 to 7: 0.1 to 1.5. At 80 to 120 ° C and at pH 7-11, the melamine, formaldehyde and alkali sulfamate are condensed and the condensation is continued until the viscosity of the 50% dry sample is at least 300 DIN sec and the 20% dry sample is 20 ° C. has a viscosity of up to 300 DIN sec measured with a 4 mm DIN spout. 2. A process according to claim 1, wherein the condensation is carried out in a molar ratio of 1: 3.0 to 6: 0.3 to 0.8. 3. The process according to claim 1, wherein the condensation is carried out at a temperature between 80 and 100 ° C. 4. The process of claim 1, wherein the condensation is carried out as long as the viscosity of the 20% dry solids aqueous solution measured at 20 ° C with a 4 mm DIN spout is at least 12 DIN sec. reach. 5. The process of claim 1 wherein the alkali sulfamate is sodium sulfamate. 3 drawings 81.1228.66-42 Alföldi Nyomda, Debrecen - Chief Executive Officer István Benkö Director Responsible for publishing: Director of Economic and Legal Publishing 1st abra. diagram Diagram 2 T Μ ¹ CM I ------> 17649? International Classification; D 21 H 3/56 C 08 G 12/32 International Classification: D 21 H 3/56 C 08 G 12/32 3) abrcj