A RELEASE AGENT COMPOSITION FOR PAPERMAKING, A RELEASE AGENT EMULSION AND PREPARATION METHOD AND APPLICATIONS THEREOF

Description

TECHNICAL FIELD

The present invention belongs to the technical field of papermaking, in particular to a release agent composition for making paper, such as crepe paper, a release agent emulsion (e.g., a micro-emulsion prepared from the composition) for making paper, such as crepe paper, and a preparation method and applications of the release agent emulsion.

BACKGROUND ART

In papermaking process, creping is one of the important means for improving the softness and feel of paper, and usually involves a process of peeling off the paper web from the dryer or the surface of the dryer, for example by using a scraper. Owing to the adhesion between the paper web and the surface of the dryer (e.g., Yankee dryer) and some other factors, a release agent emulsion is usually applied to the surface of the dryer in order to peel off the paper web entirely and prevent the abrasion of the surface of the dryer and/or the scraper (for example, resulted from the friction between the surface of the dryer and the scraper) in the creping process.

In order to reach a uniform and smooth peeling performance, a small particle size, a narrow particle size distribution and good stability of the release agent smulsion are necessary. The prior art usually prepares emulsions with a high-energy (e.g., high pressure and/or high shear force) emulsification process (e.g., high-pressure homogenization process, ultrasonic emulsification process, or micro-jet emulsification process), or a complex emulsification process or emulsification conditions (e.g., higher temperature, e.g., higher than room temperature). The high-energy emulsification process usually requires high mechanical energy or high-energy shearing emulsification equipment, such as a homogenizer (e.g., micro-jet high-pressure homogenizer), a high-speed propeller stirrer, a high-shear colloid mill, or an ultrasonic emulsifier, etc. For example, the homogenizer may operate at a rotation speed up to 8, 000-30, 000 rpm. Previous study prepared an emulsified wax using a SY-20 high-efficiency emulsifying shearer at a shearing speed of 200 to 6,200 r/min or above, and it was believed that a shearing speed of 1,200-4,200 r/min could meet the demand (Dong Xinli, “Development of a Nonionic Emulsified Paraffin” [D]. Shandong University, 2005, pp. 44-45). The above emulsifying device is expensive, leading to an increased cost of the emulsion. Although a common stirrer is helpful for reducing the cost of the emulsion, it often can't provide a satisfactory high shear force and appropriate particle size of the emulsion. Some other emulsification methods further involve a heating step, which also increases the complexity and cost of the emulsion preparation process.

In addition, during the application of the release agent emulsion, attention should be paid to its compatibility with other creping aids such as a softener, a dryer adhesive and an adhesive, so as to improve the peeling performance while avoiding side effects, such as precipitation caused by the interaction among different auxiliary agents or different components. Therefore, the selection of the components of the release agent formulation is also very important for achieving good creping performance.

To facilitate the creping operation and provide high-quality crepe paper, an improved release agent composition or emulsion is desirable in the prior art. The emulsion or an emulsion prepared from the release agent composition should have a small particle size, a narrow particle size distribution, good stability and good compatibility with other creping aids, meanwhile, the preparation process of the emulsion should be simple, and low-cost.

SUMMARY

The present invention provides a release agent composition for making paper, such as crepe paper, a release agent emulsion (e.g., a micro-emulsion prepared from the composition) for making paper, such as crepe paper, and a preparation method and applications of the release agent emulsion.

In a first aspect, the present invention provides a release agent composition for papermaking (e.g., crepe paper), which comprises or consists of: (a) a hydrophobic material; (b) a cationic surfactant (e.g., a quaternary ammonium salt type surfactant); and (c) a nonionic surfactant (e.g., a polyoxyethylene type nonionic surfactant). In some embodiments, the composition is free of anionic surfactants.

In some embodiments, the cationic surfactant comprises, or is selected from, or is a quaternary ammonium salt type surfactant. In some embodiments, the quaternary ammonium salt type surfactant is selected from one, two, three, four or more of the following: imidazoline quaternary ammonium salt surfactants, such as products of imidazoline di-fatty acid or mono-fatty acid quaternized by dimethyl sulfate or diethyl sulfate, or products of fatty acid or di-fatty acid cyclized with diethylenetriamine and then quaternized by dimethyl sulfate or diethyl sulfate, such as 9-Octadecenoic acid (Z)-, reaction products with diethylenetriamine, cyclized, di-Et sulfate-quaternized; fatty acid ester quaternary ammonium salts, such as triethanolamine fatty acid ester quaternary ammonium salts, such as products of triethanolamine di-fatty acid ester quaternized by dimethyl sulfate or diethyl sulfate, e.g., diesters formed by C_16-18 and C₁₈ unsaturated fatty acids and 2-hydroxy-N, N-bis(2-hydroxyethyl)-N-methyl-acetyl ammonium methyl sulfate salt; amidoamino quaternary ammonium salts, such as products of amidates of diethylenetriamine and di-fatty acid quaternized by dimethyl sulfate or diethyl sulfate; dialkyl (C₁₀-C₂₀) dimethyl or diethyl ammonium chlorides, or any combination thereof. In some embodiments, the cationic surfactant is selected from imidazoline quaternary ammonium salt surfactants. In some embodiments, the cationic surfactant is selected from products of imidazoline di-fatty acid or mono-fatty acid quaternized by dimethyl sulfate or diethyl sulfate, products of fatty acid or di-fatty acid cyclized with diethylenetriamine and then quaternized by dimethyl sulfate or diethyl sulfate, or any combination thereof. In some embodiments, the cationic surfactant is selected from 9-Octadecenoic acid (Z)-, reaction products with diethylenetriamine, cyclized, di-Et sulfate-quaternized, which for example, has a molecular formula of C₄₄H₈₅O₅SN₃ and/or a CAS No. of 68511-92-2.

In some embodiments, the composition comprises at least two, three, four or more nonionic surfactants. In some embodiments, the nonionic surfactant comprises, or is selected from, or is a polyoxyethylene type nonionic surfactant. In some embodiments, the nonionic surfactant comprises a first nonionic surfactant and a second nonionic surfactant. In some embodiments, the first nonionic surfactant and/or the second nonionic surfactant comprises at least one, two, three or more nonionic surfactants.

In some embodiments, the nonionic surfactant comprises, or is selected from, or is one, two, three, four or more of the following: alcohol ethoxylates, such as C₁₀-C₁₆ linear or branched alcohol ethoxylates (e.g., 1-10EO, such as 2EO, 3EO, 4EO, 5EO, 6EO, 7EO, 8EO, 9EO, or 10EO), such as C₁₀-C₁₆ linear or branched alcohol ethoxylates (2EO), C₁₀-C₁₆ linear or branched alcohol ethoxylates (7EO), C_12-13 linear/branched alcohol ethoxylates (2EO) (e.g., CAS No. 160901-19-9), C_12-13 linear/branched alcohol ethoxylates (7EO) (e.g., CAS No. 160901-19-9), or C_12-14 secondary alcohol ethoxylates (7EO) (e.g., CAS No. 84133-50-6); copolymers of polyoxyethylene and polyoxypropylene; polyoxyethylene fatty acid esters; and polyethylene glycol dioleates, such as PEG₄₀₀ dioleate; or any combination thereof. In some embodiments, the nonionic surfactant comprises, or is selected from, or is alcohol ethoxylates and polyethylene glycol dioleates. In some embodiments, the nonionic surfactant comprises, or is selected from, or is one or more of the following: polyethylene glycol dioleates (e.g., PEG₄₀₀ dioleate), C_12-13 linear/branched alcohol ethoxylates (2EO), C_12-13 linear/branched alcohol ethoxylates (7EO), C_12-14 secondary alcohol ethoxylates (7EO), or any combination thereof or all of them.

In some embodiments, the first nonionic surfactant comprises, or is selected from, or is alcohol ethoxylates and polyethylene glycol diolcates. For example, the first nonionic surfactant comprises, or is selected from, or is polyethylene glycol dioleates (e.g., PEG₄₀₀ dioleate), C_12-13 linear/branched alcohol ethoxylates (2EO), C_12-13 linear/branched alcohol ethoxylates (7EO), or any combination thereof or all of them. In some embodiments, the second nonionic surfactant comprises, or is selected from, or is alcohol ethoxylates, such as C_12-14 secondary alcohol ethoxylates (7EO).

In some embodiments, the hydrophobic material is selected from one or more of the following: mineral oil (e.g., mineral oil), vegetable oil, animal fat, biodiesel, polyethylene, polydimethyl siloxane or any combination thereof. In some embodiments, the hydrophobic material is mineral oil.

In some embodiments, the composition comprises or consists of mineral oil, imidazoline quaternary ammonium salt surfactants (e.g., products of fatty acid cyclized with diethylenetriamine and then quaternized by diethyl sulfate, such as 9-Octadecenoic acid (Z)-, reaction products with diethylenetriamine, cyclized, di-Et sulfate-quaternized), polyethylene glycol dioleates (e.g., PEG₄₀₀ dioleate), and alcohol ethoxylates [e.g., C_12-13 linear/branched alcohol ethoxylates (2EO), C_12-13 linear/branched alcohol ethoxylates (7EO) and C_12-14 secondary alcohol ethoxylates (7EO)].

In some embodiments, the hydrophobic material accounts for about 60-90 wt % of the composition by weight, such as about 70-85 wt %, about 77-80 wt % or any range or any value therebetween, such as about 75-80 wt %, about 78, about 78.5 wt %, or about 79 wt %, etc.

In some embodiments, the cationic surfactant accounts for about 2-12 wt % of the composition by weight, such as about 3.5-8 wt %, about 4-5.5 wt % or any range or any value therebetween, such as about 4-5 wt %, about 4.5 wt %, about 4.7 wt %, or about 5 wt %, etc.

In some embodiments, the nonionic surfactant accounts for about 7-35 wt % of the composition by weight, such as about 10-20 wt %, about 15-18 wt % or any range or any value therebetween, such as about 13-17 wt %, about 16-17 wt %, about 16.5 wt %, or about 17 wt %, etc.

In some embodiments, the weight ratio of the first nonionic surfactant to the second nonionic surfactant is about 3:1-1:1, such as about 2:1-1.5:1 or any range or any value therebetween, such as about 3:1-1.5:1, about 2:1-1:1, about 1.6:1, about 1.7:1, about 1.75:1, or about 1.8:1, etc.

In some embodiments, the composition comprises or consists of about 77-80 wt % of the hydrophobic material (e.g., mineral oil), about 4-5.5 wt % of the cationic surfactant (e.g., 9-Octadecenoic acid (Z)-, reaction products with diethylenetriamine, cyclized, di-Et sulfate-quaternized), and about 15-18 wt % of the nonionic surfactant (e.g., PEG₄₀₀ dioleate, C_12-13 linear/branched alcohol ethoxylates (2EO), C_12-13 linear/branched alcohol ethoxylates (7EO), C_12-14 secondary alcohol ethoxylates (7EO), or any combination thereof). In some embodiments, the weight ratio of the first nonionic surfactant to the second nonionic surfactant is about 2:1-1.5:1.

In a second aspect, the present invention provides a release agent emulsion (or micro-emulsion), which comprises: (a) a hydrophobic material; (b) a cationic surfactant (e.g., a quaternary ammonium salt type surfactant); and (c) a nonionic surfactant (e.g., a polyoxyethylene type nonionic surfactant). In some embodiments, the release agent emulsion is free of anionic surfactants.

In some embodiments, the emulsion has a particle size of 0.05-1 μm, such as about 0.08-0.8 μm, about 0.1-0.7 μm, about 0.12-0.6 μm, about 0.1-0.5 μm, about 0.1-0.2 μm, about 0.15 μm, or about 0.2 μm, etc. In some embodiments, the particle size of the emulsion is a median particle size (D_0.5) of the emulsion. In some embodiments, the particle size of the emulsion has a span value of about 1-2, such as about 1.2-1.8, about 1.35-1.65, about 1.5, about 1.54, or about 1.55, etc.

In some embodiments, the emulsion has a viscosity of about 180-250 cp (measured with a Brookfield viscometer, with a rotor No. 63, a setting of 30 revolutions, under 20° C. measuring temperature), such as about 200-240 cp, about 220-230 cp, about 230 cp, or any value or range therebetween.

In some embodiments, the component (a) hydrophobic material is the hydrophobic material defined in the various embodiments in the first aspect of the present invention. In some embodiments, the component (b) cationic surfactant is the cationic surfactant defined in the various embodiments in the first aspect of the present invention. In some embodiments, the component (c) nonionic surfactant is the nonionic surfactant defined in the various embodiments in the first aspect of the present invention.

In some embodiments, the emulsion comprises or consists of the composition according to the first aspect of the present invention and an aqueous medium (e.g., water, such as soft water). Accordingly, in some embodiments, the emulsion further comprises: (d) an aqueous medium. In some embodiments, the emulsion consists of the above-mentioned components (a), (b), (c) and (d). In some embodiments, the aqueous medium is water, such as a soft water, for example, a soft water with hardness lower than about 150 mg/L, lower than about 120 mg/L, lower than 60-120 mg/L, or even lower than about 60 mg/L. In some embodiments, the hydrophobic material accounts for about 25-50 wt % of the emulsion, such as about 30-40 wt %, about 32-35 wt % or any range or any value therebetween, such as about 31-36 wt %, about 33 wt %, or about 33.5 wt %, or about 34 wt %, etc.

In some embodiments, the cationic surfactant accounts for about 1-5 wt % of the emulsion, such as about 1.5-3 wt %, about 1.5-2.5 wt % or any range or any value therebetween, such as about 1.8-2.4 wt % or about 2 wt %, etc.

In some embodiments, the nonionic surfactant accounts for about 3-15 wt % of the emulsion, such as about 5-10 wt %, about 6.5-8 wt % or any range or any value therebetween, such as about 6-7.5 wt %, about 7 wt %, about 7.1 wt %, or about 7.2 wt %, etc. In some embodiments, the weight ratio of the first nonionic surfactant to the second nonionic surfactant is about 3:1-1:1, such as about 2:1-1.5:1 or any range or any value therebetween, such as about 3:1-1.5:1, about 2:1-1:1, about 1.6:1, about 1.7:1, about 1.75:1, or about 1.8:1, etc. In some embodiments, the first nonionic surfactant accounts for about 2-9 wt % of the emulsion, such as about 3-6 wt %, about 4-5 wt % or any range or any value therebetween, such as about 4-4.5 wt %, about 4 wt %, or about 4.5 wt %, etc. In some embodiments, the second nonionic surfactant accounts for about 1-6 wt % of the emulsion, such as about 2-4 wt %, about 2.5-3 wt % or any range or any value therebetween, such as about 2-3 wt %, about 3 wt %, or about 2.6 wt %, etc.

In some embodiments, the aqueous medium (e.g., water, such as soft water) accounts for about 40-70 wt % of the emulsion, such as about 45-60 wt %, about 50-65 wt %, about 55-60 wt %, about 56 wt %, about 57 wt %, about 57.5 wt %, or about 58 wt %, etc.

In some embodiments, the emulsion comprises or consists of (a) about 32-35 wt % of the hydrophobic material (e.g., mineral oil); (b) about 1.5-2.5 wt % of the cationic surfactant (e.g., 9-Octadecenoic acid (Z)-, reaction products with diethylenetriamine, cyclized, di-Et sulfate-quaternized); (c) about 6.5-8 wt % of the nonionic surfactant (e.g., PEG₄₀₀ dioleate, C_12-13 linear/branched alcohol ethoxylate (2EO), C_12-13 linear/branched alcohol ethoxylate (7EO) and C_12-14 secondary alcohol ethoxylate (7EO) or any combination thereof]; and (d) about 55-60 wt % of water. In some embodiments, the weight ratio of the first nonionic surfactant to the second nonionic surfactant is about 2:1-1.5:1.

In some embodiments, the emulsion is prepared through the following steps: mixing the hydrophobic material with one or more first nonionic surfactants to produce an oil phase; mixing the aqueous medium (e.g., water, such as soft water), the cationic surfactant and one or more second nonionic surfactants to produce an aqueous phase; and mixing the oil phase and the aqueous phase at a stirring rate of about 50-500 RPM, such as about 80-150 RPM, so as to produce the release agent emulsion.

In a third aspect, the present invention provides a release agent emulsion for papermaking. In some embodiments, the release agent emulsion is obtained by emulsifying the release agent composition according to any embodiment in the first aspect of the present invention. In some embodiments, the release agent emulsion is prepared from the composition according to the first aspect of the present invention. In some embodiments, the emulsification is performed at a stirring rate of about 50-500 RPM, such as about 80-150 RPM, about 80-100 RPM, about 90-110 RPM, about 75 RPM, or about 85 RPM. In some embodiments, the emulsion has a particle size of 0.05-1 μm, such as about 0.08-0.8 μm, about 0.1-0.7 μm, about 0.12-0.6 μm, about 0.1-0.5 μm, about 0.1-0.2 μm, about 0.15 μm, or about 0.2 μm, etc. In some embodiments, the particle size of the emulsion has a span value of about 1-2, such as about 1.2-1.8, about 1.35-1.65, about 1.5, about 1.54, or about 1.55, etc. In some embodiments, the emulsion is free of anionic surfactants.

In a fourth aspect, the present invention provides a method for preparing the release agent emulsion according to any embodiment in the second aspect or third aspect of the present invention. In some embodiments, the method comprises preparing the release agent emulsion from the composition according to the first aspect of the present invention. In some embodiments, the method comprises: mixing the hydrophobic material with one or more first nonionic surfactants to produce an oil phase; mixing the aqueous medium (e.g., water, such as soft water) with the cationic surfactant and one or more of second nonionic surfactants to produce an aqueous phase; and mixing the oil phase and the aqueous phase at a stirring rate of about 50-500 RPM (e.g., about 80-150 RPM, about 80-100 RPM, about 90-110 RPM, about 75 RPM, or about 85 RPM) to produce the release agent emulsion.

In some embodiments, the first nonionic surfactant comprises, or is selected from, or consists of, or is polyethylene glycol dioleates (e.g., PEG₄₀₀ dioleate), alcohol ethoxylates [e.g., C_12-13 linear/branched alcohol ethoxylates (2EO), C_12-13 linear/branched alcohol ethoxylates (7EO) or both], or any combination thereof. In some embodiments, the second nonionic surfactant comprises, or is selected from, or is alcohol ethoxylates, such as C_12-14 secondary alcohol ethoxylates (7EO). In some embodiments, the weight ratio of the first nonionic surfactant to the second nonionic surfactant is about 3:1-1:1, such as about 2:1-1.5:1 or any range or any value therebetween, such as about 3:1-1.5:1, about 2:1-1:1, about 1.6:1, about 1.7:1, about 1.75:1, or about 1.8:1, etc.

In some embodiments, the step of mixing the oil phase and the aqueous phase comprises dropwise adding (e.g., slowly) the oil phase to the aqueous phase while stirring (e.g., at a stirring rate of about 50-500 RPM, such as about 80-100 RPM, about 90-110 RPM, about 75 RPM, about 85 RPM), for example, adding the oil phase to the aqueous phase within about 20-30 min.

In some embodiments, the preparation process of the emulsion is performed at an atmospheric pressure. In some embodiments, the preparation process of the emulsion is performed at room temperature, such as at about 10-35° C., about 18-28° C., about 18-30° C., or about 20-25° C., etc.

In a fifth aspect, the present invention provides a creping aid system for papermaking, which comprises the release agent emulsion according to any embodiment in the second or third aspect of the present invention and one or more auxiliary agents. In some embodiments, the one or more auxiliary agents comprise or are selected from a group consisting of a dryer adhesive, an adhesive, a softener, a plasticizer, a modifier or any combination thereof.

In a sixth aspect, the present invention provides a method for making crepe paper, which comprises: applying (e.g., by spraying, jetting, or smearing) the release agent emulsion according to any embodiment in the second or third aspect of the present invention to the surface of a dryer (e.g., a Yankee dryer); applying a paper web to the surface of the dryer; and peeling off the dried paper web from the surface of the dryer (e.g., with a scraper) to produce the crepe paper.

In some embodiments, the method for making crepe paper comprises: applying (e.g., by spraying, jetting, or smearing) the release agent emulsion according to any embodiment in the second or third aspect of the present invention to a paper web; applying the paper web to the surface of a dryer (e.g., a Yankee dryer); and peeling off the dried paper web from the surface of the dryer (e.g., with a scraper) to produce the crepe paper.

In some embodiments, the method further comprises applying one or more auxiliary agents. In some embodiments, the one or more auxiliary agents comprise or are selected from a group consisting of a dryer adhesive, an adhesive, a softener, a plasticizer, a modifier or any combination thereof. In some embodiments, the one or more auxiliary agents are applied before, concurrently with, or after the application of the release agent emulsion.

In some embodiments, the auxiliary agent comprises or is selected from a dryer adhesive, an adhesive, a softener or any combination thereof. In some embodiments, the auxiliary agent comprises a softener. In some embodiments, the release agent emulsion and the softener are applied separately (e.g., the emulsion may be applied first, and then the softener is applied; or the softener may be applied first, and then the emulsion is applied); or the emulsion and the softener may be combined first and then applied together.

In some embodiments, the method for making crepe paper further comprises: diluting the release agent emulsion before applying it. For example, the emulsion may be diluted 10-100 times, such as about 10-50 times, about 30-70 times, about 40-80 times, about 20-60 times, etc., or any value therebetween.

In another aspect, the present invention further provides a first reagent kit, which comprises the composition according to the various embodiments in the first aspect of the present invention, an optional solvent, such as water, and an optional instructions for use. In some embodiments, the hydrophobic material, the cationic surfactant, the first nonionic surfactant and the second nonionic surfactant are packed separately. In some embodiments, the hydrophobic material and the first nonionic surfactant are packed in a first container (e.g., a bag, vial, or case), the cationic surfactant and the second nonionic surfactant are packed in a second container (e.g., a bag, vial, or case), and/or the water is packed in a third container (e.g., a bag, vial, or case).

In another aspect, the present invention further provides a second reagent kit, which comprises the release agent emulsion according to the various embodiments in the second or third aspect of the present invention and an optional instructions for use.

In another aspect, the present invention further provides an application or use of the release agent composition and the release agent emulsion according to the present invention in papermaking (e.g., crepe paper).

In another aspect, the present invention further provides a method of using the release agent composition and the release agent emulsion according to the present invention for papermaking (e.g., crepe paper). In some embodiments, the method is as described in the above aspects of the present invention.

In the various embodiments of the afore-mentioned aspects, the paper is crepe paper, such as toilet paper, including rolled toilet paper and removable pattern toilet paper; tissue paper, such as facial tissue paper (including removable pattern facial tissue paper packed in a box and removable pattern facial tissue paper packed in a plastic bag), napkin paper, and handkerchief paper; wiping paper, including hand towel, kitchen towel, etc.

In the various embodiments in the afore-mentioned aspects, the softener is a cationic surfactant, such as an amidosiloxane or cationic quaternary ammonium salt surfactant, such as a bisamide quaternary ammonium salt, an alkyl quaternary ammonium salt, an imidazoline quaternary ammonium salt, an ester-based quaternary ammonium salt, or 9-Octadecenoic acid (Z)-, reaction products with diethylenetriamine, cyclized, di-Et sulfate-quaternized, etc.

In the various embodiments of the afore-mentioned aspects, the dryer adhesive comprises modified polyvinyl amines dryer adhesive, such as a modified polyethylene imine. In some embodiments, the dryer adhesive comprises resins (e.g., thermosetting resins, non-thermosetting resins, polyaminoamide resins, polyamide resins), hemicelluloses, carboxymethyl celluloses, polyvinyl alcohols, polyvinyl amines, film-forming semi-crystalline polymers, inorganic crosslinkers, or any combination thereof.

In the various embodiments in the afore-mentioned aspects, the adhesive comprises resins (e.g., thermosetting resins, non-thermosetting resins, polyaminoamide resins, polyamide resins), hemicelluloses, carboxymethyl celluloses, polyvinyl alcohols, polyvinyl amines, film-forming semi-crystalline polymers, inorganic crosslinkers, etc.

In the various embodiments in the afore-mentioned aspects, the paper-making machine applicable to the composition, emulsion and method according to the present invention is an eTAD paper machine or any other appropriate paper-making machine known to those skilled in the art.

In the various embodiments in the afore-mentioned aspects, the release agent emulsion according to the present invention can be used by spraying, jetting, spreading, or smearing, etc.

The release agent emulsion according to the present invention or the release agent emulsion prepared with the composition and/or method according to the present invention has a very small particle size (about 0.05-1 μm), a narrow particle size distribution range, and good stability, can reach a smooth and uniform peeling performance, thereby has significant application values in the papermaking process, especially in the production of crepe paper. The release agent emulsion according to the present invention can be used in combination with a dryer adhesive, an adhesive, and a softener, etc., to adjust the viscosity between the paper web and the dryer, so that not only the paper web can be separated from the dryer easily and entirely, but also the abrasion to the surface of the dryer and scraper can be reduced, thereby the production efficiency and quality of crepe paper can be improved. Moreover, unlike the release agent emulsions commonly used in the prior art (e.g., emulsions containing an anionic surfactant), the release agent emulsion according to the present invention has excellent compatibility with cationic softeners, and no side effect such as precipitation will occur when they are used in combination.

Other aspects and advantages of the present invention will become apparent to those skilled in the art upon reading the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other objects and features of the present invention will become apparent through the following description of the present invention in conjunction with the accompanying drawings, in which:

FIG. 1 shows the particle size distribution of the release agent emulsion prepared according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The scope of the present invention is not limited to any specific embodiments described herein. The following examples are provided for illustration only.

Definitions

The following definitions are provided to facilitate understanding of the present invention, and are not intended to limit the scope of the present invention.

In the present invention, the term “optional/optionally” means that the feature defined by the term (e.g., a component, step, etc.) may exist or may not exist. For example, when referring to “optionally, wherein the nonionic surfactant comprises a first nonionic surfactant and a second nonionic surfactant” or “optionally, the emulsification is performed at a stirring rate of about 50-500 RPM, such as about 80-150 RPM”, it means that the above-mentioned feature may exist or may not exist in the technical solutions mentioned.

The term “span value (Span)” is a way to characterize the breadth of particle size distribution, and is defined as follows: Span=(D₉₀−D₁₀)/D₅₀.

The term “emulsification” refers to a phenomenon where one liquid is dispersed into the other liquid in the form of micro-droplets after the two immiscible liquids (e.g., oil and water) are mixed (e.g., by stirring), and the mixture produced under this circumstance is referred to as an emulsion.

As a measure of the droplet size in an emulsion, “median diameter D_0.5” means that 50% of the droplets in the emulsion system have a particle size smaller than D_0.5, while the other 50% of the droplets have a particle size greater than that value.

In the present invention, the terms “release agent emulsion”, “emulsion” or “micro-emulsion” can be used interchangeably, unless otherwise indicated.

In the present disclose, unless otherwise defined, all other technical terms used herein have the same meanings as commonly understood by those having ordinary skills in the art to which the present invention belongs. As for the percentages mentioned herein, unless otherwise indicated, all percentages are weight percentages.

The present invention relates to a water-based release agent emulsion, which is suitable for papermaking process, especially for the preparation process of crepe paper. For example, the emulsion of the present invention may be applied as a release agent to the wet part of the papermaking process for preparing paper for daily use. The inventors of the present application have found that when a surfactant with high HLB (e.g., 8-16) is selected for an oil-in-water emulsion, the particle size of the emulsion will be decreased as the amount of the surfactant is increased; however, once the particle size is decreased to a certain range, increasing the amount of the surfactant will not affect the particle size, and the stability of the emulsion will be affected if the amount of the surfactant is increased further. Therefore, the amount of the surfactant should be within an appropriate range.

EXAMPLES

The following examples are provided to further explain the technical scheme of the present invention, but are not intended to limit the scope of protection of the present invention.

The following components (followed by their trade names) were used in the following examples:

• • C_12-13 linear/branched alcohol ethoxylate (2EO): Safol™ 23E2;
  • C_12-13 linear/branched alcohol ethoxylate (7EO): Safol™ 23E7;
  • C_12-14 secondary alcohol ethoxylate (7EO): DOW Tergitol 15-S-7;
  • 9-Octadecenoic acid (Z)-, reaction products with diethylenetriamine, cyclized, di-Et sulfate-quaternized: MANUFACH QUAT LVOC;
  • Tall oil fatty acid: AMERIIND Unitol ALF;
  • Dryer adhesive, modified polyvinyl amine: Nalco N74939.

Example 1: Preparation of the Release Agent Emulsion of the Present Invention

Preparation of Emulsion

The components 1-4 were mixed together according to the formulation shown in the Table 1 below to prepare an oil phase; the components 5-7 were mixed together to prepare an aqueous phase; the oil phase was dropwise added to the aqueous phase slowly within 20-30 min under stirring at a stirring rate of about 80-150 RPM, to produce an emulsion.

TABLE 1
Formulation of the Release Agent Composition

			Content in	Solid
	Component		the Emulsion	Content
Example 1	No.	Emulsion Components	(wt %)	(wt %)

Oil phase	1	150# Mineral oil	33.43	78.58
	2	Polyethylene glycol (PEG400)	1.97	4.63
		dioleate
	3	C12-13 linear/branched alcohol	1.27	2.99
		ethoxylate (2EO)
	4	C12-13 linear/branched alcohol	1.27	2.99
		ethoxylate (7EO)
Aqueous	5	Soft water	57.46
phase	6	C12-14 secondary alcohol	2.60	6.11
		ethoxylate (7EO)
	7	9-Octadeconoic acid (Z)-,	2.00	4.70
		reaction products with
		diethylenetriamine, cyclized,
		di-Et sulfate-quaternized

Determination of Emulsion Properties

The particle size of the emulsion was measured with a Malvin particle size analyzer. The sample pool was subject to cycle cleaning with clean water, the background was scanned as instructed by the software, the emulsion to be tested was added dropwise into the sample pool as instructed by the software, till the turbidity reached 10-20%, and then the Test button was clicked; after the test was finished, the software calculated the results such as particle size D(_0.5) and particle size distribution. The results are shown in FIG. 1. The median particle diameter (D_0.5) of the resulting emulsion was about 0.2 μm.

The viscosity of the resulting emulsion was about 230 cp as measured. The measurement was carried out as follows: a Brookfield viscosity tester was used, a rotor No. 63 were selected and set to 30 revolution. The rotor was put into the emulsion to be tested, the bubble introduced by the rotor into the emulsion were expelled, the liquid level of the emulsion was flush with the marked line of the liquid level of the rotor, the rotor was actuated to rotate, and the viscosity was read. The measurement was made at a temperature of 20° C.

The emulsion samples were placed in an oven at 40° C. and 5° C. respectively, and the appearance change was observed every week. No phase separation was observed after 8 weeks.

The emulsion was mixed with a softener (9-Octadecenoic acid (Z)-, reaction products with diethylenetriamine, cyclized, di-Et sulfate-quaternized), and the appearance of the mixture was observed. No separation or precipitation was observed.

Example 2: Preparation of Comparative Examples of Release Agent Emulsion

Preparation of Emulsion

TABLE 2
Formulation of Comparative Example 1

			Content in
Comparative			the Emulsion
Example 1	No.	Emulsion Components	(wt %)

Oil phase	1	150# Mineral oil	33.43
	2	Polyethylene glycol (PEG400)	1.97
		dioleate
	3	C12-13 linear/branched alcohol	1.27
		ethoxylate (2EO)
	4	C12-13 linear/branched alcohol	1.27
		ethoxylate (7EO)
Aqueous phase	5	Soft water	58.46
	6	C12-14 secondary alcohol	2.60
		ethoxylate (7EO)
	7	9-Octadccenoic acid (Z)-,	1.00
		reaction products with
		diethylenetriamine, cyclized,
		di-Et sulfate-quaternized

TABLE 3
Formulation of Comparative Example 2

			Content in
Comparative			the Emulsion
Example 2	No.	Emulsion Components	(wt %)

Oil phase	1	150# Mineral oil	33.39
	2	Polyethylene glycol (PEG400)	1.96
		dioleate
	3	C12-13 linear/branched alcohol	1.28
		ethoxylate (2EO)
	4	C12-13 linear/branched alcohol	1.28
		ethoxylate (7EO)
Aqueous phase	5	Soft water	52.79
	6	C12-14 secondary alcohol	2.67
		ethoxylate (7EO)
	8	Tall oil fatty acid	5.21
	9	48% NaOH	1.42

TABLE 4
Formulation of Comparative Example 3

			Content in
Comparative			the Emulsion
Example 3	No.	Emulsion Components	(wt %)

Oil phase	1	150# Mineral oil	22.00
	2	Polyethylene glycol (PEG400)	2.00
		dioleate
	8	Tall oil fatty acid	12.00
Aqucous phase	5	Soft water	54.17
	6	C12-14 secondary alcohol	2.77
		ethoxylate (7EO)
	8	Tall oil fatty acid	5.55
	9	48% NaOH	1.51

Comparison of Emulsion Properties

TABLE 5
Comparison of Emulsion Properties among Formulations

		Particle Size		Release	Stability When
Emulsion	Particle	Distribution		Property	Combined with
Formulation	Size	(Span)	Stability	(g/in)	Cationic Softener

Example 1	0.20	1.54	Stable	172	No precipitate
Comparative	0.20	1.88	Stable	449	Precipitate
Example 2
Comparative	1.24	3.50	Stratified and	26	Precipitate
Example 3			the oil floats

The cationic softener in the Table 5 is 9-Octadecenoic acid (Z)-, reaction products with diethylenetriamine, cyclized, di-Et sulfate-quaternized.

The release property was tested through a peeling test, as follows: the dryer adhesive (Nalco dryer adhesive N74939, a modified polyvinylamines) and the release agent emulsion prepared in the above examples (diluted twice) were mixed homogeneously, and the mixture was coated with a coating bar onto an iron plate heated up to 95° C.; a wet cloth strip was pressed with a press roller to remove excessive water content, till the water contained in the cloth strip was about twice the weight of the cloth strip in a dry state; the cloth strip was attached to the coating of the mixture of dryer adhesive and release agent on the iron plate, and pressed with the press roller for 4 times, then, kept in an oven at 105° C. constant temperature for 15 min; next, the cloth strip was peeled off with an Instron 5500R tensile tester at an angle of 180 degrees, and the tensile force was measured, in unit of g/in. The smaller the tensile force was, the higher the release property was.

It can be seen from the Comparative Example 1 that when the proportion of the cationic surfactant was decreased to 1%, the particle size D(_0.5) of the obtained emulsion was about 0.176 μm. However, the emulsion in the Comparative Example 1 was unstable.

It can be seen from the Comparative Example 2 that after the cationic surfactant in the aqueous phase was replaced with an anionic surfactant, the particle size of the obtained emulsion was equivalent to the particle size of the emulsion obtained in the Example 1. However, when the emulsion was combined with a cationic softener, precipitation appeared.

The particle size D (_0.5) of the emulsion obtained in the Comparative Example 3 was about 1.242 μm, which was larger.

The above embodiments are described to facilitate those having ordinary skills in the art to understand and practice the present invention. Apparently, those skilled in the art can easily make various modifications to the embodiments and apply the general principle described herein to other embodiments without expending any creative labor. Hence, the present invention is not limited to the specific embodiments disclosed herein. All improvements and modifications made by those skilled in the art according to the principle of the present invention without departing from the scope of the present invention should be deemed as falling within the scope of protection of the present invention.