Polyamidoamine-epihalohydrin polymer and method for producing the same

Abstract

There is provided polyamidoamine-epihalohydrin (PAE) polymer substituted with an acrylic acid ester and / or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5 carbon atoms. Additionally, is provided a method for producing the PAE polymer.

Description

[0001] POLYAMIDOAMINE-EPIHALOHYDRIN POLYMER AND METHOD FOR PRODUCING THE SAME

[0002] TECHNICAL FIELD

[0003] The present disclosure generally relates to a polyamidoamine-epihalohydrin (PAE) polymer substituted with an acrylic acid ester and / or an acrylic acid amide and to a method for producing the PAE polymer.

[0004] BACKGROUND

[0005] This section illustrates useful background information without admission of any technique described herein representative of the state of the art.

[0006] In the field of papermaking art, wet strength agents have been used for a long time to enhance the strength of paper. An example of a common wet strength agent is epihalohydrin-based resin, such as polyaminoamide epichlorohydrin resin (PAE). The wet strength of a paper relates to its ability to maintain physical integrity and to resist tearing, bursting, and shredding under use, especially under wet conditions. A further property of wet strengthened paper is the softness, especially for tissue paper or the like.

[0007] Even though several epihalohydrin-based resins already exists, there is a need for new epihalohydrin-based resin that provides wet strength for paper, such as tissue paper.

[0008] SUMMARY

[0009] The following presents a simplified summary of the features disclosed herein to provide a basic understanding of some exemplary aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key / critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts disclosed herein in a simplified form as a prelude to a more detailed description.

[0010] In a first aspect the present invention provides a polyamidoamine-epihalohydrin (PAE) polymer substituted with an acrylic acid ester and / or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5, preferably from 2 to 4, carbon atoms. In a second aspect the present invention provides an aqueous solution comprising the PAE polymer according to the present invention, wherein the aqueous solution comprises from 5 to 60 wt-% of the PAE polymer based on the total weight of the aqueous solution

[0011] In a third aspect the present invention provides a method for producing polyamidoamineepihalohydrin (PAE) polymer, the method comprises: providing polyamidoamine (PAIM), providing an acrylic acid ester or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester and / or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5, preferably from 2 to 4, carbon atoms, providing epihalohydrin, preferably epichlorohydrin, and reacting the PAIM with the acrylic acid ester and / or the acrylic acid amide and with the epihalohydrin.

[0012] In a fourth aspect the present invention provides a polyamidoamine-epihalohydrin (PAE) polymer obtainable or obtained with the method according to the present invention.

[0013] In a fifth aspect the present invention provides polyamidoamine (PAIM) substituted with an acrylic acid ester and / or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester and / or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5, preferably from 2 to 4, carbon atoms, obtainable or obtained by reacting PAIM with an acrylic acid ester or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester and / or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5, preferably from 2 to 4, carbon atoms.

[0014] In a sixth aspect the present invention provides use of the PAE polymer according to the present invention or the aqueous solution according to the present invention as a wet strength agent, an emulsifier, and / or a sizing agent.

[0015] It has been surprisingly found that PAE polymers with substituent of (meth)acrylic ester or (meth)acrylic amide, in which the attached group to (meth)acrylic ester or (meth)acrylic amide contain from 2 to 5 carbon atoms, preferably from 2 to 4 carbon atoms contain significantly reduced foaming tendency. Additionally, said PAE polymers provide good wet strength properties. The appended claims define the scope of protection.

[0016] DETAILED DESCRIPTION

[0017] In a first aspect the present invention provides a polyamidoamine-epihalohydrin (PAE) polymer substituted with an acrylic acid ester and / or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5, preferably from 2 to 4, carbon atoms.

[0018] In one embodiment the substituent of the acrylic acid ester and / or the acrylic acid amide is an open chain alkyl, preferably selected from ethyl, propyl, and / or butyl, preferably butyl.

[0019] In one embodiment the substituent of the acrylic acid ester and / or the acrylic acid amide is a branched open chain alkyl, preferably selected from isopropyl, isobutyl, sec-butyl, and / or tert-butyl, more preferably the substituent of the acrylic acid ester and / or the acrylic acid amide is tert-butyl.

[0020] In one embodiment the acrylic acid ester or the acrylic acid amide is a (meth)acrylic ester and / or (meth)acrylic amide, respectively.

[0021] In one embodiment the PAE polymer is substituted by the acrylic acid ester and / or the acrylic acid amide in one or more of secondary amine groups and / or primary amine groups of the PAE backbone.

[0022] In one embodiment the acrylic acid ester or the acrylic acid amide substituents of the PAE polymer form non-polar side chains.

[0023] In one embodiment the PAE polymer comprises from 5 mol-% to 50 mol-%, preferably from 10 mol-% to 40 mol-%, more preferably from 15 mol-% to 30 mol-% of the acrylic acid ester and / or the acrylic acid amide substituent based on the total amount of substance of amine and quaternary ammonium groups of the PAE polymer.

[0024] In one embodiment the PAE polymer has a viscosity within a range from 20 cP to 1000 cP at 25 °C as measured by Brookfield DV1+ viscometer.

[0025] In one embodiment the PAE polymer is a polyamidoamine-epichlorohydrin polymer.

[0026] In a second aspect the present invention provides an aqueous solution comprising the PAE polymer according to the present invention, wherein the aqueous solution comprises from 5 to 60 wt-% of the PAE polymer based on the total weight of the aqueous solution. In one embodiment the aqueous PAE solution comprises formic acid and / or sulphuric acid.

[0027] In one embodiment the aqueous PAE solution comprises formic acid preferably from 1-15 kg / t PAE polymer solution and / or sulphuric acid preferably from 1-30 kg / t PAE polymer solution.

[0028] In one embodiment the aqueous PAE solution comprises sulphuric acid 30 kg / t PAE polymer when the aqueous PAE solution comprises 60 wt-% of the PAE polymer based on the total weight of the aqueous solution.

[0029] In one embodiment the aqueous solution has one or more of: a viscosity within a range from 20 cP to 1000 cP at 25 °C as measured by Brookfield DV1+ viscometer, a pH within a range from 2.5 to 4.

[0030] In a third aspect the present invention provides a method for producing polyamidoamineepihalohydrin (PAE) polymer, preferably the PAE polymer of the present invention, the method comprising: providing polyamidoamine (PAIM), providing an acrylic acid ester or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester and / or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5, preferably from 2 to 4, carbon atoms, providing epihalohydrin, preferably epichlorohydrin, and reacting the PAIM with the acrylic acid ester and / or the acrylic acid amide and with the epihalohydrin.

[0031] In one embodiment the method comprises reacting PAIM with the acrylic acid ester and / or the acrylic acid amide followed by reacting with epihalohydrin, preferably epichlorohydrin.

[0032] In one embodiment the method comprises recovering at least a part of the (PAIM) substituted with the acrylic acid ester and / or an acrylic acid amide prior reacting the rest of the (PAIM) substituted with the acrylic acid ester and / or an acrylic acid amide with epihalohydrin, preferably epichlorohydrin.

[0033] In one embodiment the method comprises providing the acrylic acid ester and / or the acrylic acid amide in an amount from 5 mol-% to 50 mol-%, preferable from 10 mol-% to 40 mol- %, more preferable from 15 mol-% to 30 mol-%, based on the total amount of substance of PAIM amine groups. In one embodiment the method comprises monitoring one or more of viscosity, pH, conductivity, charge density, ratio of covalently bound halogen to ionic halogen, and / or temperature of reaction mixture(s), and when one or more of the monitored properties reach(es) predetermined value(s), ending the reaction(s) and recovering PAE polymer.

[0034] In a fourth aspect the present invention provides a polyamidoamine-epihalohydrin (PAE) polymer obtainable or obtained with the method of the present invention.

[0035] In a fifth aspect the present invention provides a polyamidoamine (PAIM) substituted with an acrylic acid ester and / or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester and / or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5, preferably from 2 to 4, carbon atoms, preferably obtainable or obtained by reacting PAIM with an acrylic acid ester or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester and / or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5, preferably from 2 to 4, carbon atoms.

[0036] In a sixth aspect the present invention provides use of a PAE polymer according to the present invention or the aqueous solution according to the present invention as a wet strength agent, an emulsifier, and / or a sizing agent.

[0037] EXAMPLES

[0038] Analysis methods

[0039] Dry solids content is determined by using Mettler Toledo HR73, at 150 °C.

[0040] Viscosity is determined by using Brookfield LV DV1 , equipped with small sample adapter, at 25 °C, using spindle S18. The highest feasible rotation speed for the spindle is used. pH is determined by using a calibrated pH-meter.

[0041] Charge density is determined at pH 9.5, adjusted with 10 weight-% aqueous NaOH solution, by charge titration using polyethylene sulfonate solution as titrant. Mutek PCD-03 is used for end point detection.

[0042] Dichloropropane (DCP), tert-butyl acrylate (TBA) and n-butyl alcohol (NBA) are determined by gas chromatography. Synthesis procedure for low foaming hydrophobic PAE polymer Exp 1, according to the present invention

[0043] Condensation polymer of diethylene triamine (DETA) and adipic acid (equivalent ratio of about 1 : 1 , dry content 46.4 w-%, HCI titration equivalent 4.65 meq / g) 235 g and tert-butyl acrylate 6.5 g are dosed into a reactor equipped with a heating / cooling system, a condenser and a mixer, are mixed for 5 min and then heated to 80 °C in 30 min time, and kept at the temperature for 6 h 30 min. The mixture is cooled to 19 °C in 45 min time. Epichlorohydrin (ECH) 45.2 g is dosed in 5 min time and the reaction mixture was mixed at 19 °C for 17 h. Water 517 g is dosed into the mixture and the mixture is heated to 60 °C in 1 h 30 min time and is kept at the temperature for 2 h 30 min. Sulfuric acid was added. The mixture was cooled to 20 °C. The product Exp 1 has the following characteristics: Dry content is 20.0 %, viscosity at 25 °C is 163 cP, pH is 3.2 and charge density at pH 9.5 is 2.0 meq / g. Molar proportion of TBA is 10 mol-% of total polyamidoamine (PAIM) amines and molar proportion of epichlorohydrin (ECH) is 90 mol-% of total PAIM amines. A series of low foaming hydrophobic PAE polymers is made according to similar synthesis protocol as described in Exp 1 Results of EXP 1 - EXP4 are in table 1.

[0044] Table 1. Characteristics of low foaming hydrophobic PAE polymers

[0045] Effect of the low foaming hydrophobic PAE polymers on wet tensile strength

[0046] Performance of the low foaming hydrophobic PAE polymer of Exp 3, was tested and compared against standard PAE product.

[0047] Tested furnish was prepared from bleached softwood (50%) and hardwood (50%) pulps (refined to ca. SR°30). 80 g / m2sheets were formed with Rapid Koethen sheet former (RK) as follows: Furnish was diluted to 1% with tap water and pH and conductivity adjusted to 7 and 1.0 mS / cm. Chemical additions were made to mixing vessel (mixing speed 1000 rpm) and after chemical additions pulp was poured to RK sheet former and water was drained out through wire with suction. Sheet was removed from wire and vacuum dried at 92 °C in restrain. Before testing in the laboratory (Table 2), sheets were pre-conditioned for 24 h at 23 °C in 50 % relative humidity, according to the standard ISO 187. Before wet tensile strength measurement paper strips were immersed in water for 60 minutes.

[0048] Chemical amounts were kg dry chemical per ton dry fibre stock. In the reference point no wet strength additives were used. PAEs were added 60 seconds before sheet forming. All the test points included retention aids (CPAM 200 g / t and silica 300g / t).

[0049] Table 2. Sheet testing devices and standard methods used for produced paper sheets.

[0050] Typically, paper is considered to have wet strength if wet to dry strength ratio is over 10%. Results show (Table 3) that both PAE samples improved significantly wet and dry tensile strength properties. With low-foaming hydrophobic PAE polymer of Exp 3 strength increase was almost comparable to standard PAE. With 2kg / t addition already over 14% wet to dry ratio was observed and with 6 kg / t wet to tensile ratio was over 23%.

[0051] Table 3. Effect of PAEs on wet and dry strength.

[0052] Use of tertbutyl acrylate (TBA)- polyamidoamine-epihalohydrin (PAE) polymer according to the present invention in nonwoven

[0053] Manufactruring of nonwoven

[0054] A wetlaid nonwoven was manufactured with birch pulp (length ~1 , < 2 mm) and 10 mm viscose fibers (Kelheim Fibers). The used stock consistency was 0.2 % (2 g / l) and to enhance the wet strength of the nonwoven, polyamide epichlorohydrin based chemistry was added to the fiber slurry prior to sheet forming. The oerformance was evaluated against cationic starch and a standar PAE.

[0055] Table 4. Materials.

[0056] Wetlaying was done with a laboratory sheet former (KCL sheet former). Target areal density of the sheets was 65 g / m2The fiber composition was 70 % wood pulp and 30 % viscose. The strangth chemistries were dosed to the fiber slurry prior to sheet forming. The samples (Table 5) were dried in a drum drier in 40 C for 6 hours.

[0057] Table 5. Samples

[0058] Nonwoven testing

[0059] According to the ISO 187, the sample sheets were first conditioned for a minimum of 4 h in the climate controlled laboratory (23°C and 50 % RH) and weighed to determine the grammage.

[0060] Wet and dry tensile strength were determined from the nonwoven. Wet strength method was based "ISO 3871 : Determination of tensile properties after immersion in water" and five successful parallel measurements were done. Dry tensile strength was measured based on "ISO 12625 - Part 4: Tissue paper and Tissue products", and five successful parallel measurements were done.

[0061] Typically, the article is considered to have wet strength if wet to dry strength ratio is over 10%. Results in Table 5 show that both standard PAE and TBA-PAE polymer samples improved the tensile strength properties, especially wet strength. With the TBA-PAE polymer results are comparable to standard PAE and with 5 kg / t addition already over 16% wet to dry ratio was observed.

[0062] Table 5. Characteristics of manufactured nonwoven sheets

[0063] Various embodiments have been presented. It should be appreciated that in this document, words comprise, include, and contain are each used as open-ended expressions with no intended exclusivity.

[0064] The foregoing description has provided by way of non-limiting examples of particular implementations and embodiments a full and informative description of the best mode presently contemplated by the inventors for carrying out the invention. It is however clear to a person skilled in the art that the invention is not restricted to details of the embodiments presented in the foregoing, but that it can be implemented in other embodiments using equivalent means or in different combinations of embodiments without deviating from the characteristics of the invention.

[0065] Furthermore, some of the features of the afore-disclosed example embodiments may be used to advantage without the corresponding use of other features. As such, the foregoing description shall be considered as merely illustrative of the principles of the present invention, and not in limitation thereof. Hence, the scope of the invention is only restricted by the appended patent claims.

Claims

CLAIMS1 . A polyamidoamine-epihalohydrin (PAE) polymer substituted with an acrylic acid ester and / or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5, preferably from 2 to 4, carbon atoms.

2. The PAE polymer according to claim 1 , wherein the substituent of the acrylic acid ester and / or the acrylic acid amide is an open chain alkyl, preferably selected from ethyl, propyl, and / or butyl.

3. The PAE polymer according to claim 1 or 2, wherein the substituent of the acrylic acid ester and / or the acrylic acid amide is a branched open chain alkyl, preferably selected from isopropyl, isobutyl, sec-butyl, and / or tert-butyl, more preferably the substituent of the acrylic acid ester and / or the acrylic acid amide is tert-butyl.

4. The PAE polymer according to any one of the preceding claims, wherein the acrylic acid ester or the acrylic acid amide is a (meth)acrylic ester and / or (meth)acrylic amide, respectively.

5. The PAE polymer according to any one of the preceding claims, wherein the PAE polymer is substituted by the acrylic acid ester and / or the acrylic acid amide in one or more of secondary amine groups and / or primary amine groups of the PAE backbone.

6. The PAE polymer according to any one of the preceding claims, wherein the acrylic acid ester or the acrylic acid amide substituents of the PAE polymer form non-polar side chains.

7. The PAE polymer according to any one of the preceding claims, wherein the PAE polymer comprises from 5 mol-% to 50 mol-%, preferably from 10 mol-% to 40 mol-%, more preferably from 15 mol-% to 30 mol-% of the acrylic acid ester and / or the acrylic acid amide substituent based on the total amount of substance of amine and quaternary ammonium groups of the PAE polymer.

8. The PAE polymer according to any one of the preceding claims, wherein the PAE polymer has a viscosity within a range from 20 cP to 1000 cP at 25 °C as measured by Brookfield DV1+ viscometer.

9. The PAE polymer according to any one of the preceding claims, wherein the PAE polymer is a polyamidoamine-epichlorohydrin polymer.

10. An aqueous solution comprising the PAE polymer according to any one of claims 1 to10. wherein the aqueous solution comprises from 5 to 60 wt-% of the PAE polymer based on the total weight of the aqueous solution.11 . The aqueous solution according to claim 11 , wherein the aqueous solution comprises formic acid preferably from 1-15 kg / t PAE polymer solution and / or sulphuric acid preferably from 1-30 kg / t PAE polymer solution.

12. The aqueous solution according to claim 11 or 12, wherein the aqueous solution has one or more of: a viscosity within a range from 20 cP to 1000 cP at 25 °C as measured by Brookfield DV1+ viscometer, a pH within a range from 2.5 to 4.

13. A method for producing polyamidoamine-epihalohydrin (PAE) polymer, preferably according to any one of claims 1 to 10, the method comprising: providing polyamidoamine (PAIM), providing an acrylic acid ester or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester and / or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5, preferably from 2 to 4, carbon atoms, providing epihalohydrin, preferably epichlorohydrin, and reacting the PAIM with the acrylic acid ester and / or the acrylic acid amide and with the epihalohydrin.

14. The method according to claim 14, comprising reacting PAIM with the acrylic acid ester and / or the acrylic acid amide followed by reacting with epihalohydrin, preferably epichlorohydrin.

15. The method according to claim 14 or 15, comprising providing the acrylic acid ester and / or the acrylic acid amide in an amount from 5 mol-% to 50 mol-%, preferable from 10 mol-% to 40 mol-%, more preferable from 15 mol-% to 30 mol-%, based on the total amount of substance of PAIM amine groups.

16. The method according to any one of claims 13 to 16, comprising monitoring one or more of viscosity, pH, conductivity, charge density, ratio of covalently bound halogen to ionic halogen, and / or temperature of reaction mixture(s), and when one or more of the monitored properties reach(es) predetermined value(s), ending the reaction(s) and recovering PAE polymer.

17. The method according to claim 14, comprising recovering a part of the (PAIM) substituted with the acrylic acid ester and / or an acrylic acid amide.

18. A polyamidoamine-epihalohydrin (PAE) polymer obtainable or obtained with a method according to any one of claims 14 to 17.

19. A polyamidoamine (PAIM) substituted with an acrylic acid ester and / or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester and / or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5, preferably from 2 to 4, carbon atoms, preferably obtainable or obtained by reacting PAIM with an acrylic acid ester or an acrylic acid amide, wherein an oxygen atom of the acrylic acid ester and / or a nitrogen atom of the acrylic acid amide contains a substituent having from 2 to 5, preferably from 2 to 4, carbon atoms.

20. Use of a PAE polymer according to any of claims 1-9 or the aqueous solution according to any one of claim 10-12 as a wet strength agent, an emulsifier, and / or a sizing agent.

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