DE19548031A1 - Modified cellulose material for high wet strength in non-matured state - Google Patents

Abstract

Cellulose material obtained using water-dispersible polyisocyanate(s) and isocyanate-reactive compound(s) is claimed. The cellulose material is obtained by reacting cellulose material with water-dispersible polyisocyanate(s) and then with isocyanate-reactive compound(s), which is of formula: QTn Q = optionally branched up to 250 C hydrocarbon group, which may contain cyclic units and/or hetero-atoms, e.g. oxygen, nitrogen or sulphur; T = NH2, OH, -NHR<1> and/or -SH; R<1> = 1-2 C alkyl; and n = 2-8. Also claimed is a process for the preparation of the modified cellulose material.

Description

The invention relates to improved cellulose-containing materials, their production and use.

To improve the properties of cellulose-containing materials, in particular paper and cardboard, it is already known to use polyisocyanates.

FR-A-2 360 714 describes a method in which the already finished paper is first with a polyfunctional isocyanate-reactive groups Compound is treated and then in a second step with an isocyanate group-containing connection. Both stages of the after-treatment take place under Use of solvents. The wet strength of the paper is said to Application of this procedure can be improved, however, the two-pass the size press is time-consuming, expensive and with the use of Solvents connected. Water-dispersible polyisocyanates are not mentioned. Furthermore, we strongly advise against using the paper first with the Isocyanate and then treat with the isocyanate-reactive compound.

DE-A-42 11 480 relates to a method for wet-strengthening paper with the help water-dispersible polyisocyanate mixtures. EP-A 0582166 describes a ver drive to the use of polyisocyanates containing tert. Amino groups and / or ammonium groups and 0 to 30% by weight (based on the mixture) Ethylene oxide units in the form of polyether chains, with the aim of being dry-resistant and to produce wet-strengthened and / or glued cellulose-containing materials.

Increased requirements require papers with further improved wet and To provide dry strength. For example, it is useless moderate, time-consuming and expensive, the paper to achieve the desired To subject wet strength grades to a so-called "maturation".

The invention relates to post-treated cellulose-containing materials, obtainable under Use of at least one water-dispersible polyisocyanate and at least one isocyanate-reactive compound, characterized in that cellulosic material with the water dispersible polyisocyanate and  is then treated with the isocyanate-reactive compound, the Isocyanate-reactive compound corresponds to the following formula

QT _n ,

in what mean
Q has a linear or branched hydrocarbon radical with up to 250 carbon atoms, optionally also containing cyclic structural elements, optionally also containing heteroatoms such as O, N or S,
T -NH₂ and / or -OH and / or -NHR¹ and / or -SH
R¹ C₁ to C₂ alkyl,
n is a number between 2 and 8.

In a preferred embodiment, the freshly prepared, if necessary still moisture-containing material with the isocyanate-reactive compound delt.

The materials obtained according to the invention have a high wet strength, without maturation. The desired wet strength becomes direct achieved after the aftercare. This is a significant amount of time possible savings, since known materials only become wet in the course of a Obtain post-ripening process.

The term "water-dispersible" in connection with the invention polyisocyanates used means that these in a concentration of up to 70% by weight, preferably up to 50% by weight, of finely divided dispersions in water with particle sizes (ultracentrifuge) of <500nm. Preferred water dispersible isocyanates are described in DE-A 42 11 480 (nonionic types), EP-A- 0 582 166 (cationic types) and DE-A-195 20 092 (anionic types) already described.  

In the case of the invention for the aftertreatment of the freshly prepared, given if still moisture-containing, cellulose-containing material to be used poly functional compounds having isocyanate-reactive groups prefers those with amino functions.

The cellulose-containing materials are preferably paper, Cardboard and cardboard. You can still use wooden components in the processed state, contain in particular lignin, but also be exempt from it.

Preferred water-dispersible polyisocyanates are known from EP-A-582 166:

• (Ia) polyisocyanate mixtures
  • 1) Polyiso cyanates containing tertiary amino and / or ammonium groups and
  • 2) unmodified polyisocyanates,
• (Ib) polyisocyanate mixtures
  • 1) polyiso cyanates containing tertiary amino and / or ammonium groups,
  • 2) unmodified polyisocyanates,
  • 3) tertiary amino and / or ammonium groups and polyether groups containing polyisocyanates, and
  • 4) polyisocyanates containing polyether groups,
• (Ic) polyisocyanate mixtures
  • 1) Polyiso cyanates containing tertiary amino and / or ammonium groups and
  • 2) unmodified polyisocyanates,
  • 5) tertiary amino and / or ammonium groups and hydrophobic groups containing polyisocyanates, and
  • 6) polyisocyanates containing hydrophobic groups,
• (Id) polyisocyanate mixtures
  • 1) Polyiso cyanates containing tertiary amino and / or ammonium groups and
  • 2) unmodified polyisocyanates,
  • 3) tertiary amino and / or ammonium groups and polyisocyanates containing polyether groups,
  • 4) polyisocyanates containing polyether groups,
  • 5) polyisocyanates containing tertiary amino and / or ammonium groups and hydrophobic groups,
  • 6) polyisocyanates containing hydrophobic groups,
  • 7) tertiary amino and / or ammonium groups, hydrophobic groups and polyisocyanates containing polyether groups, and
  • 8) Polyether groups and hydrophobic groups containing polyiso cyanates, or mixtures of the polyisocyanate mixtures (Ia) to (Id).

Further preferred water-dispersible polyisocyanates are from DE-A-42 11 480 known:

• I) water-dispersible nonionic polyisocyanate mixtures from Polyisocya naten and polyether-modified polyisocyanates with cycloaliphatic and / or aliphatically bound isocyanate groups,
• II) Polyisocyanate mixtures of polyisocyanates and carboxylate group modifi graced polyisocyanates with cycloaliphatic and / or aliphatic which isocyanate groups or
• III) water-dispersible, nonionic polyisocyanates with aromatic bunches which isocyanate groups or mixtures of such polyisocyanates.

Water-dispersible polyisocyanate mixtures (I) are preferably used. With

• a) an average NCO functionality of 1.8 to 4.2,  
• b) a content of aliphatic and / or cycloaliphatic iso cyanate groups (calculated as NCO, molecular weight = 42) from 12.0 to 21.5% by weight, based on the polyisocyanate mixture (I), and
• c) a content of ethylene oxide arranged within polyether chains units (calculated as C₂H₄O, molecular weight = 44) from 2 to 20 wt .-%, based on polyisocyanate mixture (I), the polyether chains have a statistical average of 5 to 70 ethylene oxide units.

Further particularly preferred water-dispersible polyisocyanates can be according to DE-A 195 20 092 by implementation

• a) organic polyisocyanates with an average NCO functionality of 1.8 up to 4.2,
• b) NCO-reactive compounds containing (potentially) anionic groups and if necessary
• c) polyalkylene oxide alcohols, amines and / or thiols

be preserved. In general, it is possible to use, as structural components (b) for introducing ionic groups, compounds which, in addition to at least one NCO-reactive group, also have at least one anionic group (such as, for example, carboxylate, sulfonate, phosphate, phosphonate, or phosphinate group). Compounds which, in addition to at least one NCO-reactive group, contain at least one group capable of forming an anionic group per molecule are suitable as structural components (b) for introducing potentially anionic groups. Such potentially anionic groups are, for example, carboxyl, sulfo, phosphonic acid, phosphoric acid and phosphinic acid groups. Preferred components (b) are therefore above all compounds which have carboxyl or sulfo groups capable of salt formation: Preferred components (c) comprise mono- and polyhydric, in particular monohydric, polyether alcohols. Suitable components (c) thus primarily include poly-C₂-C₆-, preferably -C₂-C₃-alkylene ethers started on monohydric alcohols. Instead of hydroxyl end groups, the polyalkylene ethers (c) can also carry amino or mercapto end groups. The polyisocyanates preferably have a content of built-in polyalkylene ether groups, calculated as recurring alkyleneoxy groups [0-alkylene] _X , of 3 to 25% by weight, based on polyisocyanate A. The polyalkylene ether groups preferably contain 50 to 100% by weight of ethylene oxide units and, in addition to these, preferably exclusively propylene oxide units. Accordingly, preference is given to ethylene oxide polyether and ethylene oxide / propylene oxide mixed polyether with a predominant proportion by weight of ethylene oxide units. Pure ethylene oxide polyethers are preferred. The built-in polyethylene oxide blocks can have an average molecular weight of 220 to 6000, preferably 500 to 3000. The polyisocyanates can be prepared by reacting the polyisocyanates (a) with components (b) and optionally (c) simultaneously or in any order one after the other. A preferred reaction temperature is 50 to 120 ° C; the reaction is generally complete within 1 to 3 hours.

Preferred polyfunctional compounds containing isocyanate-reactive groups are polyamines. Preferred polyamines are all aliphatic Amino functions. Particularly preferred polyamines correspond to at least one of the following formulas

• meaning:
  n 0 to 15
  m 1 to 15
  Z CH or N
  R²H or CH₃
  AH, CH₃ or (CH₂) _p -NHR²,
  p 1-15 in what mean
  m, n the same or different, an integer from 0 to 15
  V NH, O or S as well W NH and / or O or S, and o is an integer from 0 to 15, identical or different from m and n,
  in what mean
  R³ and R⁴ H or CH₃, with the proviso that one of the radicals is H, with the meaning or their salts with acids in the
  R² and m have the meanings given above and
  Q₁ an at least divalent hydrocarbon radical having 2 to 25 carbon atoms
  p is a number between 2 and 8 and an alkyl radical with 1 to 6 carbon atoms and / or hydrogen,
  U is an alkyl radical with 1 to 6 carbon atoms and / or hydrogen
  or mixtures of the polyamines a) to d) can be used.

As far as substituents in the compounds to be used according to the invention, If links and / or indices occur several times, they have one another independent meaning.

The following compounds are examples of representatives of the polyamines a) named: Diethylenetriamine, N, N ′, N ′ ′ - trimethyldiethylenetriamine, bis- (3-amino propyl) amine, bis (3-aminopropyl) methylamine, dipropylenetriamine, propylenediamine, Ethylene diamine, N, N'-dimethyl diamine, N, N'-dimethyl propylene diamine, 1-amino-3- methylaminopropane, 1,4-diaminobutane, 1,6-diaminohexane, 2,5-diamino-2,5- dimethylhexane.

The following compounds are examples of representatives of the polyamines b) named: triethylene triamine, tetraethylene pentamine, pentaethylene hexamine, and end permanent polyether structures having amino groups such as, for example, as ATPE (amino-terminated polyethers) are known and for example in US-A- 3 847 992, 38 076, EP-PS 0 297 536, EP 0 356 046, DE 28 32 759 will.

The following compounds are examples of representatives of the polyamines c) named: guanidine, cyanoguanidine, guanidinium sulfate, carbonate, nitrate, aminogua nidin.

The following compounds are examples of representatives of the polyamines d) called: reaction products obtainable by reaction of saturated aliphatic  C₂ to C₁₀ dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, di glycolic acid or sebacic acid or their functional derivatives such as anhydrides and esters, with aliphatic polyamines, having at least two primary ones Contain amino groups and at least one secondary or tertiary amino group ten, as described in DE-OS 19 06 450 and DE-A-41 36 289. The moles ratios when using the polyamines and the dicarboxylic acids are 0.5- 8: 1, preferably 0.7-6.5: 1.

The invention further relates to a method for producing the invention Cellulose-containing materials, characterized in that they are used in the Production with a water-dispersible polyisocyanate and then with the treated polyfunctional compound having isocyanate-reactive groups becomes.

In a preferred embodiment, the polyisocyanate is the cellu loose material added in bulk, while the polyfunctional, iso Compound having cyanate-reactive groups thereafter already as a sheet or Web present cellulosic material are added.

In a particularly preferred embodiment, the water is used dispersible isocyanates in bulk. For this, the water-dispersible Isocyanate either with vigorous stirring for the manufacture of paper, cardboard or cardboard provided fiber suspension either added directly as it is under Influence of strong shear forces emulsified themselves, or in the form of a separately made aqueous dispersion added.

Of course, the water-dispersible isocyanates with the in EP-A 0582166 and DE-OS 42 11 480 tools used together will. Then, by draining the fiber suspension, the cellulose-containing one Material formed. This process is carried out on a paper machine.

The process according to the invention includes the aftertreatment of the cellulose neck term material, preferably the cellulose-containing material paper with polyfunk tional, isocyanate-active compounds. This Nachbe action is possible by spraying, vapor deposition or application by roller, Rollers, brushes, blades, scrapers or knives. The application is preferably by means of Glue or film presses of the type customary in the paper industry. Especially  The immediate aftertreatment of the cellulose-containing material is expedient in Glue or film presses that are connected "on line" to the paper machine.

The polyfunctional, isocyanate-reactive groups to be used according to the invention compounds are used for the application to the cellulose-containing Material used dissolved in water. The application concentration is usually 0.005 to 20% by weight, preferably 0.05 to 10% by weight. Of course you can other aids such as surface sizing agents with the polyfunctional isocyanate-reactive groups according to the invention Compounds used together in aqueous solution.

The process according to the invention also gives cellulose-containing materials very good wet and dry strength as well as good sizing properties. The obtained wet and dry strengths and sizing properties are through Conditioning such as B. by post-condensation at elevated temperature can be improved.

In the following examples, the percentages relate to weight percent Cent, unless otherwise stated.  

Examples Water dispersible isocyanate

83 g of one by trimerizing part of the isocyanate groups of 1,6-diisocy anatohexane produced, isocyanurate polyisocyanate, which in essentially from tris (6-isocyanatohexyl) isocyanurate and its higher homo Logen exists and an NCO content of 21.4%, a content of monomeric 1,6-diisocyanatohexane <0.3% and a viscosity of 3000 mPas (23 ° C) has (NCO functionality about 4.0), with 16 g one is 2- (2-meth oxyethoxy) ethanol started polyether based on ethylene oxide with a Number average molecular weight of 350 g / mol and a hydroxyl number of 160 mg KOH / g and 1 g of diethylethanolamine implemented. After the reaction is complete the product was used with propylene glycol diacetate to a solids content of 80%. NCO = 12%; Viscosity (25 ° C) = 500 mPas.

Amidamine I

73 g adipic acid (0.5 mol) and 206.4 g diethylenetriamine (2 mol) become Reaction brought, the diethylenetriamine submitted at 90 ° C and the adipine acid is added in portions (within 2.5 hours).

After the addition has taken place, the reaction mixture is stirred at 120 ° C. for 2 h. There after all in a nitrogen atmosphere at 140-180 ° C within 3 h volatile constituents are distilled off. In the end it is slow and careful vacuum applied and this increased to 0.2 mbar.

The residue is a highly viscous substance (yield 158 g) with a Solids content of 58% is dissolved in water. Base equivalent weight: 275 g / val for the aqueous solution.

Amidamine 2

As in the above regulation (amidamine I) are implemented with one another:
73.0 g adipic acid (0.5 mol)
180.3 g ethylenediamine (0.3 mol).

After removing the volatile components at 140 ° C / 10mbar one remains solid waxy substance left that is water-soluble, yield 113.3 g; Bases equivalent weight: 185 g / val.

Amidamine 3

As in the regulation for amidamine 1, the following are implemented:
73 g adipic acid (0.5 mol)
264 g of N-methyl 1,3 propanediamine.

After all volatile components have been distilled off, a highly viscous remains Liquid remaining, 60% dissolved in water, yield 119 g; Bases equivalent weight: 286 g / val (for the aqueous solution).

Amidamine 4

As in the regulation for amidamine 1, the following are implemented:
176.0 g adipic acid (1 mol)
152.3 g bis (3aminopropyl) methylamine (1.05 mol).

After all volatile components have been distilled off, a highly viscous remains Liquid remaining (264.3 g yield), which was 50% solids dissolved in water becomes; Base equivalent weight of the solution 486 g / val.

Application examples 1 to 6

Papers with a basis weight of 80 g / m² were used using 1% Active substance of the water-dispersible isocyanate based on cellulose 80% softwood pulp, 20% hardwood pulp with a freeness of 350 SR pH 7 produced. The papers are finished on a laboratory size press from Mathis, Zurich, Switzerland, type HF. The wet absorption of the paper at the Post-treatment of the paper was 65%. The wet break load was both uncondensed (i.e. only dried) and in the condensed state, i.e. H. to Determined for 30 minutes in a drying cabinet at 110 ° C.

After conditioning, 5 paper strips of 1.5 cm are made from each sheet of paper Cut out width and immersed in distilled water for 5 minutes. After that the wet strips are immediately subjected to their wet breaking load in a tensile testing machine checked.  

The results surprisingly show that the Ver paper obtained uncondensed already have a much higher wet strength results than when using the water-dispersible isocyanate alone. The determined values are summarized in Table I.

Table I

Application examples 7-24

As in the application examples 1-6 paper with a surface area weight of 80 g / m² with 0.5 and 1% active substance of the water-dispersible Iso cyanates based on pulp from 80% softwood and 20% hardwood pulp with a freeness of 350 SR at pH 7. This uncondensed Papers are typed on a laboratory size press from Mathis, Zurich, Switzerland HF treated with the appropriate glue liquor. Table II provides information about the values found, the wet breaking load was as in experiments 1-6 checked.

The advantageousness of the invention results from the table modern materials due to the improved strength after treatment with a Amine over such materials that do not have such post-treatment have experienced.

Claims (9)

1. Cellulose-containing materials, obtainable using at least one water-dispersible polyisocyanate and at least one isocyanate-reactive compound, characterized in that cellulose-containing material is treated with the water-dispersible polyisocyanate and then with the isocyanate-reactive compound, the isocyanate-reactive compound corresponding to the following formula: QT _n , wherein mean
Q has a linear or branched hydrocarbon radical with up to 250 carbon atoms, optionally also having cyclic structural elements, optionally also containing heteroatoms such as O, N or S,
T -NH₂ and / or -OH and / or -NHR¹ and / or -SH
R¹ C₁ to C₂ alkyl,
n is a number between 2 and 8. 2. Cellulose-containing material according to claim 1, characterized in that it is paper, cardboard or cardboard. 3. Cellulose-containing material according to at least one of the preceding Claims, characterized in that it contains wood.   4. Cellulose-containing material according to at least one of claims 1 and 2, characterized in that there are essentially no lignin components contains more. 5. Cellulose-containing material according to at least one of the preceding Claims, characterized in that the water-dispersible polyiso cyanate at a concentration of up to 70% in water during treatment a fine-particle dispersion with particle sizes in an ultracentrifuge <500 nm results. 6. Cellulose-containing material according to at least one of the preceding claims, characterized in that the polyfunctional, iso cyanate-reactive group-containing compound is a polyamine, which preferably corresponds to at least one of the following formulas

• meaning:
  n 0 to 15
  m 1 to 15
  Z CH or N
  R² H or CH₃
  AH, CH₃ or (CH₂) _p -NHR²,
  p 1 to 15 in what mean
  m, n the same or different, an integer from 0 to 15
  V NH, O or S as well W NH and / or O or S and O is an integer from 0 to 15, identical or different from m and n,
  in what mean
  R³ and R⁴ H or CH₃, with the proviso that one of the radicals is H, with the meaning or their salts with acids in the
  R² and m have the meanings given above and
  Q₁ is an at least divalent hydrocarbon radical having 2 to 25 carbon atoms
  p is a number between 2 and 8 and an alkyl radical with 1 to 6 carbon atoms and / or hydrogen,
  U is an alkyl radical with 1 to 6 carbon atoms and / or hydrogen
  or mixtures of the polyamines a) to d) can be used.

7. A process for the preparation of post-treated cellulose-containing materials, characterized in that the cellulose-containing material is treated with at least one water-dispersible polyisocyanate and then with at least one isocyanate-reactive compound, the iso-cyanate-reactive compound corresponding to the following formula QT _n in which
Q has a linear or branched hydrocarbon radical with up to 250 carbon atoms, optionally also containing cyclic structural elements, optionally also containing heteroatoms such as O, N or S,
T -NH₂ and / or -OH and / or -NHR¹ and / or -SH
R¹ C₁ to C₂ alkyl,
n is a number between 2 and 8. 8. Process for the production of cellulose-containing, possibly wood-containing Materials according to claim 7, characterized in that the Nachbe handling of the cellulose-containing material by applying the polyfunk tional compounds having isocyanate-reactive groups on the Surface of the cellulose-containing materials using a glue or film press he follows.   9. The method according to at least one of claims 7 and 8, characterized in that the water-dispersible polyisocyanate and the isocyanate-reactive compound are used in the following concentrations, based on the dry pulp used:
Water-dispersible polyisocyanate: 0.001 to 20% by weight
Isocyanate-reactive compound: 0.005 to 20% by weight