CN1329415C - Wet strength agent and method for production thereof - Google Patents

Abstract

The invention relates to a method for producing a wet strength agent, comprising: in a first step, reacting a nitrogen-containing polymer with a hydrophobic compound to form a hydrophobic side chain substituent on the polymer; in a second step, reacting the obtained hydrophobic nitrogen-containing polymer with a crosslinking agent The reaction forms a cationic nitrogen-containing resin, and the third step forms particles by emulsion polymerizing one or more ethylenically unsaturated monomers in the presence of the resulting wet strength resin. The invention also relates to wet strength agents and resins. The invention further relates to the use of said agents and resins in cellulosic suspensions, in the production of paper, preferably tissue paper, and to paper, preferably tissue paper, comprising wet strength resins or agents.

Description

Wet strength agent and its production method

This application is a divisional application of the Chinese patent application 00814795.7 with the application date of November 14, 2000, entitled "wet strength agent and its production method".

The present invention relates to a paper wet strength agent and a method of producing the same. The invention further relates to a method of producing paper comprising adding a paper wet strength agent to an aqueous cellulosic suspension and to paper comprising the paper wet strength agent. Furthermore, the invention relates to the use of paper wet strength agents as additives to aqueous cellulosic suspensions.

Background of the invention

In the field of papermaking, wet strength agents such as epichlorohydrin based resins (eg polyaminoamide epichlorohydrin resins) have been used for a long time to increase the strength of paper. These resins are disclosed in US 3,700,623 and US 3,772,076. The wet strength of paper relates to its ability to maintain physical integrity and resist tearing, cracking and shredding when used, especially when used under wet conditions. An important property of wet strength paper, especially tissue paper, is flexibility. Flexibility can be described as the tactile sensation felt when the paper is held or rubbed against the skin.

US 5,200,036 discloses a wet strength agent providing paper with enhanced wet strength. The cationic polyaminoamide epichlorohydrin resin is partially modified by introducing a polymerizable unsaturated hydrocarbon, thereby providing it with ethylenically unsaturated side chain substituents. The resin is then added to the colloid-forming monomers whereby copolymerization occurs resulting in the formation of bonds between the polymerizable unsaturated hydrocarbon moieties of the resin and the latex-forming monomers. The reaction is facilitated by the addition of emulsifiers, whereby the desired suspension of latex particles formed is obtained. Resin particles of the above-mentioned type are also used as emulsifiers. Often these resins are insufficiently effective as sole emulsifiers, so these emulsifiers are used in combination with other compounds.

US 5,314,721 discloses a process for the preparation of vinyl polymer dispersions comprising resins based on cationic polyaminoamides whose terminal groups have been modified to have at least 7 carbon atoms and derived from monocarboxylic acids. Chain aliphatic hydrocarbyl substitution. The product obtained is used as a sizing agent.

US4,416,729 discloses a method for the preparation of wet strength additives, comprising contacting a linear polyamidoamine with an α,β-ethylenically unsaturated carboxylic acid compound to form a substituted polyamidoamine, and combining the substituted polyamidoamine with a polyamine Contacting forms a branched polyamidoamine with pendant amine groups, and contacting the branched polyamidoamine with an epihalohydrin thereby forming pendant curable ammonium moieties on the branched polyamidoamine. US 4,416,729 does not disclose the use of the prepared wet strength additive for the production of tissue paper.

Although the above-mentioned epichlorohydrin-based resins show sufficient wet strength and emulsifying properties in certain applications, there is a need to be able to provide further and improved paper wet strength agents and methods of providing these agents. There is also a need to be able to provide wet strength resins and reagents. Furthermore, there is a need for further resins that provide improved emulsifying properties.

this invention

Further and improved wet strength agents for paper can be obtained according to the present invention by compositions comprising polymeric particles and hydrophobic hydrocarbon groups providing pendant substituents on wet strength resins. New methods of producing these wet strength resins and agents have also been discovered. It has also been found that the wet strength agents and resins produced by the method of the present invention impart improved flexibility to the paper without adversely affecting the absorbent properties.

More specifically, the present invention relates to paper wet strength agents comprising polymer particles and a wet strength resin comprising a cationic nitrogen-containing polymer having hydrophobic side chain substituents. The present invention further relates to a method of producing a paper wet strength agent comprising: a first step reacting a nitrogen-containing polymer with a hydrophobic compound to provide a nitrogen-containing polymer having hydrophobic side chain substituents, and a second step reacting the resulting product with a crosslinking agent To form a cationic wet strength resin, the third step is to emulsion polymerize one or more ethylenically unsaturated monomers in the presence of the formed wet strength resin. Furthermore, the present invention relates to a paper wet strength agent obtainable by the process described above. The present invention also relates to a new wet strength resin and a method of making a wet strength resin according to the two first steps described herein. The invention also relates to a method of producing paper comprising adding a paper wet strength resin or agent to a cellulose suspension and to the use of a paper wet strength resin or agent for producing paper. The invention also relates to paper comprising a paper wet strength resin and an agent. The invention is further defined by the appended claims.

The present invention provides resins and agents having the property of imparting improved wet strength to paper. The present invention also provides a simple, convenient and efficient synthetic route for the preparation of wet strength resins and reagents. Accordingly, the wet strength resins and agents of the present invention can be prepared in high yields.

The present invention also provides wet strength resins and agents that can produce paper with enhanced flexibility properties. The flexibility of a paper sheet can be characterized by means of the relative wet strength value, which is characterized by the ratio between the wet tensile index and the dry tensile index according to the formula RWS (percentage) = (WS/DS) x 100, where RWS means relative wet strength, WS is wet tensile index and DS is dry tensile index of paper. RWS is thus a measure of the flexibility of the paper; the higher the RWS, the more flexible the paper. The wet strength resins and agents of the present invention also provide improved emulsifying properties and can be used as the sole emulsifier without the addition of additional compounds which would cause undesirable foam formation.

The term "wet strength agent" as used herein refers to an agent capable of imparting better wet strength properties to paper than paper without the agent. Wet strength agents include wet strength resins. As used herein, the term "wet strength resin" refers to a resin capable of imparting better wet strength properties to paper than paper without the resin.

A method of producing a paper wet strength agent comprising the first step of reacting a nitrogen-containing polymer with a hydrophobic compound to provide a nitrogen-containing polymer having hydrophobic side chain substituents, the second step of reacting the resulting product with a crosslinking agent to form a wet strength resin, The third step forms particles by emulsion polymerizing one or more ethylenically unsaturated monomers in the presence of the resulting wet strength resin. According to a preferred embodiment, the polyamine having at least 2 secondary and/or primary amine moieties added between the first and the second step or after the second step is left unreacted.

The nitrogen-containing polymer is suitably a polyaminoamide, polyamine or other nitrogen-containing polymer. Polyaminoamides which are the reaction products of polycarboxylic acids, suitably dicarboxylic acids, and polyamines may be used. The term "carboxylic acid" is meant to include carboxylic acid derivatives such as anhydrides and esters. Suitable polycarboxylic acids include saturated or unsaturated aliphatic or aromatic dicarboxylic acids. The polycarboxylic acids preferably contain less than 10 carbon atoms. Suitable polycarboxylic acids include oxalic acid, malic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid and derivatives thereof. Mixtures of these compounds may also be used. Suitable polyamines include polyalkylene polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenetriamine, and the like or mixtures thereof. Furthermore, any polyaminoamide prepared according to the method disclosed in EP 802215A1 (herein incorporated by reference) may be used. The molecular weight of the nitrogen-containing compound is suitably from 100 to 50,000, preferably from 500 to 10,000, and the ratio of polyamine to polycarboxylic acid is suitably from 0.49:1 to 1.49:1, preferably below 1.3:1, for example from 1.3:1 to 0.7: 1. Diethylenetriamine is suitably reacted with adipic acid to form the polyaminoamide.

The hydrophobic compound used may suitably contain carboxylate groups or derivatives thereof. The hydrophobation reaction between the nitrogen-containing polymer and the hydrophobic compound can be carried out by alkylation, olefin addition or other reactions. The addition of alkenes can be illustrated by the following schematic reaction:

Wherein VVV-NH-VVV represents a nitrogen-containing polymer moiety, and C=C-COOR represents a vinyl-containing hydrophobic compound. The vinyl group of the hydrophobic compound, ie the C=C group, can react with the nitrogen atom of the polymer. R represents a hydrophobic group of a hydrophobic compound, which can be an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group or a cycloalkenyl group. Once the alkene reaction is available, the vinyl unsaturation of the hydrophobic compound becomes saturated after reaction with the nitrogen atoms of the polymer.

According to a preferred embodiment, the hydrophobic compound is a saturated compound or an unsaturated compound, resulting in a nitrogen-containing polymer with saturated side chain substituents.

The hydrophobic compound may contain a hydrophobic group comprising up to 40 carbon atoms, preferably 6 to 40 carbon atoms, and most preferably 8 to 40 carbon atoms.

The hydrophobic chain of the hydrophobic compound may be covalently linked to the nitrogen-containing polymer through a chain of atoms which may contain at least one heteroatom.

Hydrophobic compounds may be selected from (meth)acrylates, alkenyl (meth)acrylates, alkyl (meth)acrylamides, esters, ethers, diazo compounds, carboxylic acids, anhydrides, epoxides, alkyl Sulfonates, alkylsulfates and mixtures thereof or derivatives thereof containing hydrophobic groups, preferably selected from the group consisting of alkyl (meth)acrylates, alkyl (meth)acrylamides, alkylsulfonates, alkylsulfates Esters, diazo compounds, ethers, or epoxides or mixtures thereof, most preferably selected from alkyl (meth)acrylates, alkyl (meth)acrylamides or mixtures thereof. Examples suitably include α,β-unsaturated esters or amides such as lauryl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, N-alkyl(meth)acrylamides, N-alkylaminoalkanes N,N-dialkylaminoalkyl(meth)acrylamide, N-alkylaminoalkyl(meth)acrylate, N,N-dialkylaminoalkyl(meth)acrylamide Acrylates, Hexyl Chloride, 2-Ethylhexyl Chloride, Octyl Chloride, Decyl Chloride, Dodecyl Chloride, Hexadecyl Chloride, Octadecyl Chloride, Ethyl Epoxide, Propyl Epoxide , (n-, tert-, iso-) butyl epoxide, pentyl epoxide, hexyl epoxide, 2-ethyl-hexyl epoxide, octyl epoxide, decyl epoxide, dodeca Alkyl epoxide, hexadecyl epoxide, octadecyl epoxide, hexene, 2-ethyl-hexene, octene, decene, dodecene, hexadecene and decacene Octene.

The reaction is suitably carried out in water, pure substance or other solvent capable of at least partially dissolving the reactants under the reaction conditions without participating in the reaction, for example an organic solvent such as methanol, ethanol, ethylene glycol or the like. Mixtures of these solvents may also be used. The reaction is preferably carried out in water. The molar ratio of nitrogen-containing polymer (in amino moles) to hydrophobic compound may be at least 1:1, suitably from 2:1 to 99:1, preferably from 3:1 to 40:1. The reaction temperature may be from about 25°C to about 150°C, preferably from about 60 to about 90°C.

In a second step, the hydrophobized nitrogen-containing polymer is reacted with a crosslinker. The term crosslinking agent or crosslinking agent as used herein refers to a compound having the property of crosslinking resins and/or forming bonds with cellulosic fibers. Cross-linking agents, sometimes called internal linkers (in EP 802215A1 various internal linkers are described, incorporated herein by reference) may suitably include epihalohydrins such as epichlorohydrin; diepoxides, diacrylic acid esters, dimethacrylates, diacrylamides and dimethylacrylamides, and use mixtures or derivatives thereof. Preference is given to using chlorohydrins as crosslinkers.

The reaction is suitably carried out in aqueous solution, in pure form or by using other solvents than water such as ethanol, propanol or the like or mixtures thereof. The solvent is suitably non-reactive with the reactants under the reaction conditions employed. The reaction is preferably carried out in water. The reaction temperature may be from about 0°C to about 150°C, preferably from about 4 to about 80°C. The molar ratio of the hydrophobized nitrogen-containing polymer (by amino mole) to the crosslinking agent in the reaction composition may be 10:1 to 1:10, preferably 2:1 to 1:2.

In a third step of the invention, the process comprises emulsion polymerizing one or more ethylenically unsaturated monomers in the presence of the wet strength resin formed after the second step herein. These monomers may be selected from styrene, butadiene, vinyl acetate, vinyl amides, alkyl (meth)acrylamides, alkyl (meth)acrylates such as methyl (meth)acrylate, (meth)acrylate Base) butyl acrylate, glycidyl butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate ester, (meth)acrylonitrile; isoprene, or 1,6-hexanediol diacrylate, or mixtures or derivatives thereof. As a result of the polymerization process, the formed wet strength resin can be fixed to the formed polymer particles, resulting in a wet strength agent. As the initiator of the polymerization reaction, conventional initiators can be used. For example, Wako VA 044 can be used. The initiator is preferably water-soluble. In emulsion polymerization, the wet strength resin acts as an emulsifier during particle formation. The particles formed may consist of one or a mixture of the unsaturated ethylenically polymerizable monomers listed above. The reaction is preferably carried out in water, an organic solvent such as ethanol, propanol or the like, or a mixture of organic solvents or a mixture of water and organic solvents. The reaction temperature may be from 4°C to about 150°C, preferably from about 30 to about 90°C. The weight ratio of resin to monomer may be from 100:1 to 1:100, suitably from 10:1 to 1:50.

The reaction also relates to a method of preparing a wet strength resin comprising the first and second steps of the method as described above.

The present invention also relates to a wet strength agent comprising polymer particles and a wet strength resin comprising a cationic nitrogen-containing polymer having saturated hydrophobic side chain substituents and a crosslinker derivative.

The polymer particles can be formed from the polymerized monomers described above. The monomers are preferably selected from styrene, acrylates and mixtures or derivatives thereof.

Cationic nitrogen-containing polymers are derivatives having saturated hydrophobic side chain substituents and a crosslinker attached to the nitrogen atoms of the polymer.

Examples of suitable nitrogen-containing polymers include known commercial products which may be prepared as described above or by conventional methods known in the art. Examples of suitable nitrogen-containing polymers include polyaminoamides, alkylpolyamines, polyimines and polyvinylamines.

Hydrophobic saturated side chain substituents are attached to nitrogen atoms of nitrogen-containing polymers. The term hydrophobic side chain substituent here includes, for example, hydrophobic groups comprising a hydrophobic straight or branched hydrocarbon chain which can be covalently bonded via a heteroatom to the nitrogen atom of the nitrogen-containing polymer. Hydrophobic groups may also include cyclic chains (including cyclic hydrocarbons). Combinations of linear, branched and cyclic hydrocarbons are also included in the concept of hydrophobic groups.

The hydrophobic group of the hydrophobic side chain may contain up to 40 carbon atoms, preferably 6-40 carbon atoms, most preferably 8-40 carbon atoms.

Hydrophobic side chain substituents can be derived from, for example, alkyl (meth)acrylates, alkyl (meth)acrylamides, esters, ethers, diazo compounds, carboxylic acids, anhydrides, epoxides, alkyl sulfonates , or alkyl sulfates, or derivatives thereof containing hydrophobic groups, preferably derived from alkyl (meth)acrylates, alkyl (meth)acrylamides, alkyl sulfonates, alkyl sulfates, heavy The nitrogen compounds, ethers, or epoxides or mixtures thereof are most preferably derived from alkyl (meth)acrylates, alkyl (meth)acrylamides or mixtures thereof.

Specific examples include substituents derived from α,β-unsaturated esters or amides such as lauryl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, N-alkyl(meth)propylene Amides, N-Alkylaminoalkyl(meth)acrylamides, N,N-Dialkylaminoalkyl(meth)acrylamides, N-Alkylaminoalkyl(meth)acrylates, N,N-Dioxane Aminoalkyl(meth)acrylate, Alkylsulfonate, Alkylsulfate, Hexyl Chloride, 2-Ethylhexyl Chloride, Octyl Chloride, Decyl Chloride, Dodecyl Chloride, Hexadecyl Chloride , octadecyl chloride, ethyl epoxide, propyl epoxide, (n-, tert-, iso-) butyl epoxide, pentyl epoxide, hexyl epoxide, 2-ethyl-hexyl Epoxide, Octyl Epoxide, Decyl Epoxide, Dodecyl Epoxide, Hexadecyl Epoxide, Octadecyl Epoxide, Hexene, 2-Ethyl-Hexene , octene, decene, dodecene, hexadecene and octadecene.

Other suitable substituents may be derived from substituted succinic anhydrides containing groups selected from alkyl, alkenyl, aralkyl or aralkenyl, and ketene dimers or multimers. Further examples of suitable substituents may be derived from the compounds disclosed in WO98/39376 (herein incorporated by reference).

Derivatives of the cross-linking agent can be attached to the nitrogen-containing polymer, which has the potential to form bonds to the nitrogen-containing polymer and/or cellulosic fibers. Derivatives of crosslinkers can be derived from epihalohydrins such as epichlorohydrin, diepoxides, diacrylates, dimethacrylates, diacrylamides and dimethylacrylamides, or mixtures or derivatives thereof can be used . The crosslinking agent is preferably derived from epichlorohydrin.

According to a preferred embodiment, the cationic nitrogen-containing polymer is a polyaminoamide-epichlorohydrin resin or a polyamine-epichlorohydrin resin with saturated hydrophobic side chains. At least 10% to preferably up to about 100% of the nitrogen atoms of the cationic resin suitably comprise cationic groups. Up to 100%, preferably up to 50%, most preferably 5-30% of the nitrogen atoms of the resin suitably comprise hydrophobic groups. The wet strength agent suitably comprises a composition of polymer particles and a wet strength resin dissolved in a solvent, preferably the wet strength agent comprises an aqueous composition. The solids content of the aqueous composition is suitably from 5 to 50% by weight.

The invention further relates to wet strength resins as described above.

The invention also relates to the use of the above-mentioned paper wet strength resins and agents for the production of paper, preferably tissue paper. This use involves adding resins or agents to an aqueous suspension containing cellulose fibres. The amount of resin added to the dry cellulose fibers may be in any proportion, suitably 1-70, preferably 5-50, more preferably 15-50, and most preferably 25-50 kg per ton of dry cellulose fibers. The grammage of the paper produced is suitably below about 70 g/m ² , preferably below about 60 g/m ² , most preferably below 40 g/m ² . The paper strength resins and agents are preferably produced as aqueous dispersions comprising the resin, water and optionally emulsified particles. The dispersion can then be added to an aqueous cellulosic suspension to treat the cellulosic fibers forming paper. Paper wet strength resins and agents can also be added to the paper produced and thus provide a surface treatment for the paper. In addition, wet strength resins or agents may be combined with other chemicals commonly used in paper production known in the art such as sizing agents, softeners, retention aids, dewatering agents, dry strength agents, charge control agents or any other conventional Chemical agents such as guar gum, carboxymethylcellulose, polyacrylamide, polystyrene are added together. In addition, conventional fillers described in WO97/37080, such as clay, calcium carbonate, titanium dioxide, talc, aluminum silicate, calcium sulfate, calcium silicate, etc. may be added thereto. In addition, wet strength agents may be added to the cellulosic fiber-containing suspension in any proportion. Aqueous dispersions containing resins or reagents may be subjected to removal of toxic by-products by means of ion exchange, electrodialysis, enzymatic treatment, filtration, steam stripping, etc. Add any toxic products such as 3-MCPD, DCP to the cellulosic suspension. These methods are further described in eg EP666242A1, EP510987A1 and WO92/22601.

The present invention further relates to a method of producing paper, preferably tissue paper, comprising adding to an aqueous cellulosic suspension a paper wet strength resin and/or agent as described above and exemplified herein. The present invention also relates to paper, preferably tissue paper, comprising wet strength resins and/or agents as described above and exemplified herein. Tissue, generally referring to items such as face, hand and toilet tissue used as personal hygiene products, consists of two key elements: a substrate formed from a flat material commonly referred to as tissue, and a substrate supported on the substrate. softener. In this context, tissue paper also includes household and industrial applications such as wiping objects with the aid of kitchen rollers and the like. The tissue is usually produced from an aqueous suspension of cellulosic fibers to which wet strength agents have been added. The aqueous suspension containing cellulose fibers is then suitably dewatered to a concentration of about 7% to 25% water by means of vacuum dewatering and compression operations such as reverse mechanical elements (e.g. cylindrical rollers), whereby moist fibers are obtained Paper rolls of vegan fibers. The dewatered roll is further pressed during transfer and suitably dried by means of flow drum apparatus known in the art such as a Yankee dryer. Vacuum can also be applied to the paper roll as well as the Yankee dryer drums, thereby optionally causing additional compression between the drums, thus forming the tissue structure. The substrate may consist of a single ply of tissue or may comprise a laminate of two or more plies of tissue. In either case, since the substrate is formed from tissue paper, it is considered to be relatively thin relative to its dimensions in its main plane. Due to the relatively thin planar material, the substrate will have two major surfaces. The four main physical properties of tissue paper are its strength, its flexibility, its absorbency (especially to aqueous systems), and its lint resistance (especially when wet), such as WO95/ Further described in 01478. Production methods for the production of tissue paper are further described in WO95/01478, incorporated herein by reference. More specific applications of tissue paper include receiving and containing exudates from the body, which can be used to wipe parts of the body to remove substances from the body, and which can be used to deposit substances thereon. The paper wet strength resins or agents of the present invention suitably have hydrophobic side chains containing 6 to 40 carbon atoms, preferably 8 to 40 carbon atoms. Hydrophobic side chains can be derived from (meth)acrylates, alkenyl (meth)acrylates, alkyl(meth)acrylamides, esters, ethers, diazo compounds, carboxylic acids, anhydrides, epoxides, alkanes Alkyl sulfonates, alkyl sulfates and mixtures or derivatives thereof containing hydrophobic groups, preferably selected from the group consisting of alkyl (meth)acrylates, alkyl (meth)acrylamides, alkyl sulfonates, alkyl Sulfate esters, diazo compounds, ethers, or epoxides or mixtures thereof, most preferably selected from alkyl (meth)acrylates, alkyl (meth)acrylamides or mixtures thereof. Other suitable hydrophobic side chains may be derived from substituted succinic anhydrides containing groups selected from alkyl, alkenyl, aralkyl or aralkenyl, and ketene dimers or polymers. Further examples of suitable hydrophobic side chains may be derived from the hydrophobic compounds disclosed eg in WO 98/39376, US 9,922,243 (incorporated herein by reference). The grammage of the produced tissue is suitably below about 70 g/m ² , preferably below about 60 g/m ² , most preferably below 40 g/m ² . The amount of resin or agent added to the specified amount of dry cellulosic fibers may be in any proportion, suitably from about 1 to about 70 kg per ton of dry cellulosic fibres, preferably from about 5 to about 50, more preferably from about 15 to about 50, and Most preferably from about 25 to about 50 kg/ton dry cellulosic fibers. According to a preferred embodiment, additional dry strength agents such as starch, guar gum, carboxymethylcellulose (CMC) or synthetic dry strength agents such as anionic or amphoteric polyacrylamides can be combined with the paper wet strength agent resin of the present invention or agents are added together, although the amount of paper wet strength resin or agent of the present invention added to the aqueous cellulosic suspension is from about 5 to about 50 kg/ton of dry cellulosic fibers. In order to adjust the suitable dry strength of the tissue paper produced, those skilled in the art can suitably select the hydrophobic wet strength resin or agent to obtain the desired tissue paper, thus by adding the appropriate amount of the resin or agent to the aqueous suspension Control the wet strength of tissue paper. Tissue papers with high relative wet strength can thus be easily achieved.

The invention thus being described, it will be obvious that the embodiments may be varied in many ways. Such changes are not considered to depart from the spirit and scope of the invention, and such changes obvious to those skilled in the art are considered to be included within the scope of the claims. Although the following examples provide a more detailed description of the reactions, the following general principles can be disclosed here. The following examples further illustrate how the present invention is implemented, but do not limit the scope of the present invention.

Example 1

Polyaminoamide (hereinafter referred to as PAIM) (produced from adipic acid and diethylenetriamine) reacts with hydrophobic compounds (addition of alkenes): 240 g (0.60 amino-mol equivalent) PAIM (53% aqueous solution) and 27.3 g (0.15 mol) of 2-ethylhexyl acrylate (2-EHAc) was heated at 80° C. for 6 hours and 30 minutes. Then, 176 g of water were added and the solution was cooled to room temperature. The conversion rate of acrylate was 99.7%.

307g of the above hydrophobic PAIM solution was reacted with 30ml of epichlorohydrin (ECH) at 6°C for 6min. The temperature was then raised until 20°C was reached. The temperature is then raised until 50° C. and a viscosity of 120 mPas are reached, at which point 155 ml of water are added and the temperature is adjusted to 65° C. so that the viscosity reaches 120 mPas. The reaction was quenched by adjusting the pH to 3.5 by adding 11 ml of sulfuric acid (50%).

Emulsion polymerization: The ratio of resin to styrene is 1:2.

A solution of 47 g of the wet strength resin produced above, 104 g of water and 1.5 ml of antifoam (10% in water) was purged with nitrogen. The temperature was then raised to 50°C, at which point 0.5 g WakoVA044 and 1 ml styrene were added to the solution. After 10 minutes, additional styrene was added (total amount: 25 g). After 5 h at 50 °C, the temperature was raised to 70 °C and the solution was kept at this temperature for 1 h.

Example 2

Polyaminoamide (hereinafter referred to as PAIM) reacts with 2-ethylhexyl acrylate (2-EHAc) (addition of alkenes): 82g (0.20 amino-mol equivalent) PAIM (52% aqueous solution), 1.84g ( 0.01 mol) of 2-ethylhexyl acrylate (2-EHAc) and 43 g of water were heated at 80° C. for 2 hours. The conversion rate of acrylate was 98.9%.

15.4 ml of epichlorohydrin (ECH) was added to 125 g of the above hydrophobized PAIM solution within 6 min at 6°C. The temperature was then raised until 20°C was reached. The temperature is then raised until 65° C. and a viscosity of 120 mPas are reached, at which point 86 ml of water are added. The temperature was raised to 65°C and maintained at 65°C until the viscosity reached 120 mPas. The reaction was quenched by adjusting the pH to 3.5 by adding 11 ml of sulfuric acid (50%).

Emulsion polymerization: The ratio of resin to styrene is 1:0.5. A solution of 88.5 g of the above wet strength resin, 92 g of water and 1.5 ml of antifoam (10% in water) was purged with nitrogen. The temperature was raised to 45°C. Add 0.04g Wako VA 044 and 2ml styrene. The temperature was then raised to 50°C. After 10 minutes, additional styrene (total: 12 g) was added. After 3 h at 50 °C, the reaction mixture was cooled to room temperature.

Example 3

260 g (0.65 amino-mol equivalents) of PAIM (53% in water) and 25% of 41.0 g (0.16 mol) of dodecyl acrylate (alkene addition) were heated at 80° C. for 4 h 30 min. 211 g of water were subsequently added, and the mixture was then cooled to room temperature.

Then 302 g of the above hydrophobized PAIM was reacted with 30 ml (0.20 mol) of epichlorohydrin (ECH) at 6° C. for 4 min. The temperature was then raised until 20°C was reached. The temperature is then increased until reaching 50° C. and a viscosity of 120 mPas. Then 185 ml of water are added, the temperature is raised to 65° C. and maintained at this temperature until the viscosity reaches 120 mPas. The reaction was quenched by adjusting the pH to 3.5 by adding 10 ml of sulfuric acid (50%).

Emulsion polymerization: The ratio of resin to styrene is 1:1. A solution of 75.0 g of the above wet strength resin, 100 ml of water and 1 ml of antifoam (10% in water) was purged with nitrogen. The temperature was raised to 50°C, at which point 30mg Wako VA 044 and 1ml styrene were added. After 10 minutes, additional styrene (total: 20.5 g) was added. After 5 h at 50 °C, the temperature was raised to 70 °C and maintained at this temperature for 1 h.

Example 4

In emulsion polymerization, butyl acrylate is used instead of styrene. 75 g of the wet strength resin of Example 3 (13% solids) and 1.5 g of antifoam (10% in water) were purged with nitrogen. The temperature was raised to 45°C. Then 0.03g Wako VA 044 and 2ml butyl acrylate were added, at which point the temperature was raised to 50°C. After 10 minutes, styrene (total amount: 14.2 ml) was added. After 2h50min at 50°C, the temperature was raised to 70°C and kept at this temperature for 1 hour.

Example 5

25% 2-ethylhexyl acrylate was used to make PAIM hydrophobic. Emulsion Polymerization: 121 g of the wet strength resin of Example 1 (28% solids), 131 g of water and 1 ml of antifoam (10% in water) were purged with nitrogen. The temperature was raised to 45°C. Then 0.04g Wako VA 044 and 2ml monomer mixture (styrene: 1,6-hexanediol diacrylate = 0.375:.125) were added, at which point the temperature was raised to 50°C within 10min. Then the monomer mixture (total amount: 17 g) was added. After 3 h at 50 °C, the reaction mixture was cooled to room temperature.

Example 6

25% 2-ethylhexyl acrylate was used to make PAIM hydrophobic. A monomer mixture of styrene and tert-butyl acrylate (0.45:0.05) was used. Emulsion Polymerization: A solution of 121 g of the wet strength resin of Example 1 (28% solids), 131 g of water and 1 ml of antifoam (10% in water) was purged with nitrogen. The temperature was raised to 45°C. Then 0.04g Wako VA 044 and 2ml monomer mixture (styrene: tert-butyl acrylate = 0.45:0.05) were added, and the temperature was raised to 50°C within 10 min. Then the monomer mixture (total amount: 17.0 g) was added. After 3 h at 50 °C, the reaction mixture was cooled to room temperature.

Example 7

630 g (1.67 amino-mol equivalents) of PAIM (56% in water) and 12% (0.2 mol) of dodecyl acrylate (alkene addition) were heated at 80° C. for 6 h. 326 g of water were subsequently added, and the mixture was then cooled to room temperature. The conversion rate of acrylate: >99%.

Then 1005 g of the above hydrophobized PAIM was reacted with 155 g (1.68 mol) of epichlorohydrin (ECH) at 6° C. for 4 min. The temperature was then raised until 20°C was reached. The temperature is then increased until reaching 50° C. and a viscosity of 120 mPas. Then 287 ml of water are added, the temperature is raised to 65° C. and maintained at this temperature until the viscosity reaches 100 mPas. The reaction was quenched by adjusting the pH to 3.5 by adding 50 ml sulfuric acid (50%) and 513 ml water.

Example 8

309.5 g (0.81 amino-mol equiv.) of PAIM (55% in water) and 15% (0.12 mol) of benzyl chloride (alkylation reaction) were heated at 60° C. for 6 h. The mixture was then cooled to room temperature.

Then 125.5 g of the above hydrophobized PAIM was reacted with 17.7 g (0.19 mol) of epichlorohydrin (ECH) at 6° C. for 4 min. The temperature was then raised until 20°C was reached. The temperature is then increased until reaching 50° C. and a viscosity of 120 mPas. Then 33 ml of water are added, the temperature is raised to 65° C. and maintained at this temperature until the viscosity reaches 100 mPas. The reaction was quenched by adjusting the pH to 3.5 by adding 6 ml of sulfuric acid (50%).

Example 9

350 g (0.91 amino-mol equiv.) of PAIM (55% in water) and 15% (0.14 mol) of 2-ethylhexyl glycidyl ether (alkylation reaction) were heated at 60° C. for 7.5 h. The mixture was then cooled to room temperature.

Then 130.4 g of the above hydrophobic PAIM was reacted with 17.7 g (0.19 mol) of epichlorohydrin (ECH) at 6° C. for 4 min. The temperature was then raised until 20°C was reached. The temperature is then increased until reaching 50° C. and a viscosity of 120 mPas. Then 33 ml of water are added, the temperature is raised to 65° C. and maintained at this temperature until the viscosity reaches 100 mPas. The reaction was quenched by adjusting the pH to 3.5 by adding 5.7 ml of sulfuric acid (50%).

Example 10

274 g (0.71 amino-mol equivalents) of PAIM (55% in water) and 3.8% (0.027 mol) of alkyl ketene dimers (C18-chains) were heated at 60° C. for 6 h. The mixture was then cooled to room temperature.

Then 127.2 g of the above hydrophobic PAIM was reacted with 17.7 g (0.19 mol) of epichlorohydrin (ECH) at 6° C. for 4 min. The temperature was then raised until 20°C was reached. The temperature is then increased until reaching 50° C. and a viscosity of 120 mPas. Then 33 ml of water are added, the temperature is raised to 65° C. and maintained at this temperature until the viscosity reaches 100 mPas. The reaction was quenched by adjusting the pH to 3.5 by adding 5.7 ml of sulfuric acid (50%).

Example 11

274 g (0.71 amino-mol equivalents) of PAIM (55% in water) and 5% (0.036 mol) of alkenylsuccinic anhydride (C18-chain) were heated at 60° C. for 6 h. The mixture was then cooled to room temperature.

Then 124.3 g of the above hydrophobic PAIM was reacted with 17.7 g (0.19 mol) of epichlorohydrin (ECH) at 6° C. for 4 min. The temperature was then raised until 20°C was reached. The temperature is then increased until reaching 50° C. and a viscosity of 120 mPas. Then 33 ml of water are added, the temperature is raised to 65° C. and maintained at this temperature until the viscosity reaches 100 mPas. The reaction was quenched by adjusting the pH to 3.5 by adding 5.7 ml of sulfuric acid (50%).

Example 12

185.4 g (0.48 amino-mol equivalents) of PAIM (54% in water) and 10% (0.048 mol) of hexanediol diacrylate (90%) were heated at 80° C. for 4.5 h. The mixture was then cooled to room temperature. The conversion rate of acrylate: >99%.

Then 124.0 g of the above hydrophobized PAIM was reacted with 17.7 g (0.19 mol) of epichlorohydrin (ECH) at 6° C. for 4 min. The temperature was then raised until 20°C was reached. The temperature is then increased until reaching 50° C. and a viscosity of 120 mPas. Then 33 ml of water are added, the temperature is raised to 65° C. and maintained at this temperature until the viscosity reaches 100 mPas. The reaction was quenched by adjusting the pH to 3.5 by adding 5.7 ml of sulfuric acid (50%).

application test

Sheets are prepared on a dynamic sheet former "Formette". A furnish consisting of 35% CTMP and 65% TCF was refined to 25° SR. The paper was manually cured at 105° C. for 10 min, and then the paper was treated according to DIN 5312. Tensile tests were carried out as described in DIN 53112. For the warm tensile test, the paper was soaked for 60 minutes at room temperature. For comparison, data is also given for paper prepared by using conventional polyaminoamide epichlorohydrin resins. Note also that the papers given in Tables 1-4 below have been tested on three different occasions using different loadings of wet strength agents. In Examples 1-6, 20 kg of wet strength agent/ton of cellulose fibers was added. The paper grammage is 55g/m ² . In Examples 7-12, the paper grammage was 30 g/m ² and the wet strength resin was added in amounts of 15, 20 and 30 kg/ton of cellulose fibers. According to the above results, the observed value of relative intensity varies in each case. Reference resins, ie conventional resins, have therefore been measured in each case, as shown in Tables 1-4 below. As can be seen from the examples, the wet strength resin and the agent show excellent effects at the same addition amount as compared with the conventional resin used as a reference.

Table 1

sample Dry tensile index Nm/g Wet tensile index Nm/g Relative Wet Strength% conventional resin 49 13 27 Example 1 Wet Strength Emulsion 37 14 37 Example 2 Wet Strength Emulsion 51 15 30 Example 3 Wet Strength Resin 37 12 32 Example 3 Wet Strength Emulsion 37 13 34 Example 4 Wet Strength Emulsion 33 12 36 Example 5 Wet Strength Emulsion 35 11 31 Example 6 Wet Strength Emulsion 37 12 33

Table 2

Sample 15kg/ton of paper Dry tensile index Nm/g Wet tensile index Nm/g Relative Wet Strength% conventional resin 40.3 9.7 23.9 Example 7 Wet Strength Resin 31.6 9.3 29.5 Example 8 Wet Strength Resin 38.3 11.0 28.7 Example 9 Wet Strength Resin 33.6 9.0 26.7 Example 10 Wet Strength Resin 40.3 10.7 26.6 Example 11 Wet Strength Resin 35.3 10.7 30.2 Example 12 Wet Strength Resin 38.6 10.3 26.7

table 3

Sample 20kg/ton of paper Dry tensile index Nm/g   Wet tensile index Nm/g Relative Wet Strength% conventional resin 41.6 10.3 24.8 Example 7 Wet Strength Resin 31.6 9.3 29.5 Example 8 Wet Strength Resin 38.0 10.8 28.5 Example 9 Wet Strength Resin 35.0 10.0 28.6 Example 10 Wet Strength Resin 39.3 11.0 28.0 Example 11 Wet Strength Resin 35.0 11 31.4 Example 12 Wet Strength Resin 37.3 10.7 28.6

Table 4

Sample 30kg/ton of paper Dry tensile index Nm/g Wet tensile index Nm/g Relative Wet Strength% conventional resin 40.0 10.7 26.7 Example 7 Wet Strength Resin 31.6 10.0 31.6 Example 8 Wet Strength Resin 39.3 11.7 29.7 Example 9 Wet Strength Resin 34.0 11.0 32.4 Example 10 Wet Strength Resin 38.3 11.3 29.6 Example 11 Wet Strength Resin 34.3 11.3 33.0

Claims (5)

1. A method for preparing wet-strength resin, characterized in that comprising the first step nitrogen-containing polymer and the hydrophobic compound containing 6-40 carbon atoms to react to form a hydrophobic side chain substituent containing 6-40 carbon atoms, wherein, The nitrogen-containing polymer is selected from polyaminoamides, polyamines or mixtures thereof, and the hydrophobic compound is selected from alkyl (meth)acrylates, alkyl (meth)acrylamides, alkyl sulfonates, alkyl sulfates , diazo compound, ether or epoxide or a mixture thereof, and the second step reacts the obtained hydrophobic nitrogen-containing polymer with a crosslinking agent to form a cationic nitrogen-containing resin. 2. The method according to claim 1, characterized in that the hydrophobic compound is a saturated compound or an unsaturated compound, resulting in a nitrogen-containing polymer having saturated side chain substituents. 3. Process according to claim 1 or 2, characterized in that the nitrogen-containing polymer is a polyamine or a polyaminoamide. 4. Process according to claim 1 or 2, characterized in that the crosslinking agent is epichlorohydrin. 5. Paper wet strength resin, characterized in that the resin comprises a compound selected from the group consisting of alkyl (meth)acrylates, alkyl (meth)acrylamides, alkyl sulfonates, alkyl sulfates, diazo compounds, A cationic nitrogen-containing polymer containing a saturated hydrophobic side chain substituent of 6-40 carbon atoms of a compound of an ether or an epoxide or a mixture thereof; and a group derived from a crosslinking agent, the nitrogen-containing polymer being selected from poly Aminoamides, polyamines or mixtures thereof.