Liquid glue for paper

Abstract

Provided is a liquid paste that is for paper and that can be applied to further various applications and needs by having a compositional makeup and components different from those in conventional products. The liquid paste is particularly a liquid paste that is unlikely to generate wrinkles. In a preferable embodiment of the liquid paste according to the present invention, the contained amount of solid content (nonvolatile matter) excluding water is 40-70 wt%. The solid content substantially comprises a water-soluble modified polysaccharide and a low-molecular-weight sugar (molecular weight of 1000 or less). The weight ratio (weight of low-molecular-weight sugar / weight of modified polysaccharide) of the low-molecular-weight sugar with respect to the modified polysaccharide is 0.4-12. The liquid paste has a viscosity (BL-type viscometer, 6 rpm) of 700-8000 mPa / s. In a particularly preferable embodiment of the liquid paste according to the present invention, the water-soluble modified polysaccharide is hydroxyalkylated starch, other processed starch, or dextrin, and the low-molecular-weight sugar is a monosaccharide or a disaccharide such as sucrose, fructose, glucose, xylose, maltose, and trehalose, or an oligosaccharide such as xylitol and sorbitol.

Description

Technical Field

[0001] The present invention relates to a liquid glue used for pasting papers. In particular, it relates to a liquid glue used for pasting office papers such as printer papers and office envelopes, or for pasting them onto other papers or fabrics, and having the property of being difficult to wrinkle.

Background Art

[0002] In recent years, as office glue, generally liquid glue or solid glue (stick glue, tape glue) has been mainly used instead of the paste-like traditional starch glue. Liquid glue is usually colorless and transparent, put in a flexible tube-shaped container, discharged through the "sponge" or porous sheet at its tip, and applied to papers or the like. Almost all commercially available liquid glues are composed of a viscous aqueous solution of polyvinyl alcohol (PVA).

[0003] As a liquid glue, it has advantages such as being easier to quickly apply over a wider area than stick glue or the like, and being able to achieve a stronger adhesive force than stick glue or the like after drying for a while. However, liquid glue has a problem that it may wrinkle.

[0004] Recently, "non-wrinkling glue" (Fuji Gohsei Co., Ltd.) mainly composed of polysaccharides has been commercially available (Non-Patent Document 1).

[0005] On the other hand, as a food additive, modified starch such as hydroxyalkylated starch may be used (Non-Patent Documents 2 to 3). Hydroxyalkylated starch may also be used in the manufacture of pharmaceutical preparations, and has also been proposed for addition to detergents (Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Non-Patent Document

[0007]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Disclosure of the Invention

Problems to be Solved by the Invention

[0008] The present invention aims to provide a liquid paste for paper, particularly a liquid paste that is less likely to wrinkle, which can meet more diverse uses and needs due to different components and compositions from the prior art.

Means for Solving the Problems

[0009] In a preferred embodiment, the liquid paste for paper of the present invention has a solid content (non-volatile content) excluding water of 35 to 70% by weight, preferably 40 to 70% by weight. The solid content substantially consists of a water-soluble modified polysaccharide (including a water-soluble starch derivative, a cellulose derivative, and dextrin) and a low-molecular-weight saccharide (monosaccharide to tetrasaccharide, or a molecular weight of 1000 or less or 800 or less). The weight ratio of the low-molecular-weight saccharide to the modified polysaccharide ([weight of low-molecular-weight saccharide]÷[weight of modified polysaccharide]) is 0.4 to 12, preferably 0.5 to 11 or 0.6 to 10, more preferably 0.7 to 8 or 0.9 to 6, still more preferably 1 to 4 or 1 to 3. The viscosity (BL viscometer, 6 rpm) is 500 to 10000 mPa / s, preferably 700 to 8000 mPa / s, more preferably 1000 to 7000 mPa / s.

[0010] Here, "substantially" means that, for example, 90% by weight or more, or 95% by weight or more of the solid content consists of these two compound species. Also, "water-soluble" includes cases where a stable dispersion is formed even if it is not a complete aqueous solution, and preferably means that a transparent paste liquid is formed and can maintain a transparent state even after, for example, 3 months of storage.

[0011] The water-soluble modified polysaccharide is a compound species having a molecular weight of at least more than 800 or 1000, preferably 2000 or more or 3000 or more, and generally can be used as a "thickener". The water-soluble starch derivative is one having water solubility imparted or increased by etherification, oxidation, partial esterification, etc. Preferred among the water-soluble starch derivatives may include water-soluble ones among the processed (chemical modified) starches (Non-Patent Document 3).

[0012] Water-soluble starch derivatives are, in preferred embodiments, nonionic (i.e., those not containing acid salts or phosphate groups), and in particular, hydroxyalkylated starches, oxidized starches, and the like. Hydroxyalkylated starches are preferably hydroxypropylated starches (hydroxypropyl starches), but may also be hydroxyethylated starches, hydroxybutylated starches, etc., or a combination of multiple types of hydroxyalkylated starches. The molar substitution degree (MS: the number of moles of alkylene oxide bonded per anhydrous glucose unit) of the hydroxyalkylated starch can be 0.04 to 0.4, preferably 0.05 to 0.35, and more preferably 0.08 to 0.25. Also, the hydroxyalkylation in the present application may introduce a methyl group, an ethyl group, etc. together with a hydroxyalkyl group, such as hydroxypropyl-methylated starch. It may also be combined with oxidation for introducing a carboxyl group, etc.

[0013] As the water-soluble etherified starch, methylated starch can be used, but carboxymethylated starch (sodium starch glycolate), etc. may also be used. These etherification degrees (substitution degrees) can preferably be, for example, 0.04 to 0.4, 0.05 to 0.35, or 0.08 to 0.25. Also, the water-soluble cellulose derivatives can be water-soluble cellulose ethers such as carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, etc. The etherification degree (substitution degree) here can be, for example, 0.3 to 1.7 or 0.4 to 1.5. Note that these etherified starches or starch derivatives may, if necessary, be combined with treatments such as introducing a carboxyl group by oxidation.

[0014] Hydroxyalkylated starch, other modified starches, or starch derivatives, and cellulose derivatives may or may not have undergone a treatment to reduce the molecular weight of the polysaccharide sugar chain (reduce viscosity). That is, the molecular weight (weight-average molecular weight by SEC) can be adjusted to 10,000 to 700,000, preferably 50,000 to 450,000, more preferably 70,000 to 300,000 or 80,000 to 250,000 by appropriately adding enzymes, oxidants, acids, heat, etc. and performing hydrolysis treatment. The hydrolysis treatment can preferably be carried out after hydroxyalkylation, but can also be carried out before hydroxyalkylation. Here, the measurement of the molecular weight can be performed, for example, using a DMSO / DMF (75 / 25) solvent with added LiBr as the eluent and a sample dissolved by heating in DMSO (https: / / www.shodex.com / ja / dc / 03 / 06 / 02.html). In addition, the aqueous solution viscosity (30% water content, 30 °C, 60 rpm) of hydroxyalkylated starch can be 50 to 1000 mPa·s or 70 to 600 mPa·s. Here, the water content in hydroxyalkylated starch or other modified starches can be about 5 to 7% by weight.

[0015] As the starch serving as the raw material for hydroxyalkylated starch, other modified starches, or starch derivatives, waxy corn starch and waxy potato starch are particularly preferably used. That is, those with a low amylose content (high degree of branching) and easy gelatinization are preferred. However, in some cases, general (non-waxy) potato starch and tapioca starch can also be used.

[0016] In this application, water-soluble "modified starches" or starch derivatives and "starches" shall include various dextrins. In addition, as the water-soluble modified polysaccharide or the polysaccharide serving as its base, in some cases, α-glucans such as dextran and other non-ionic thickening polysaccharides can be used.

[0017] When using a relatively low molecular weight substance and the viscosity of the liquid paste is insufficient, polysaccharide thickeners such as guar gum, gum arabic, xanthan gum, and pullulan, particularly non-ionic polysaccharide thickeners, can be added. As a result, for a combination of "modified starch" or a starch derivative and a polysaccharide thickener, the aqueous solution viscosity (30% aqueous solution at 30 °C and 60 rpm in the water-containing state) can be made to be 50 - 1000 mPa·s or 70 - 600 mPa·s.

[0018] In a particularly preferred embodiment, the liquid paste for paper of the present invention is substantially composed of 4 - 45 wt% or 4 - 40 wt% (particularly 15 - 30 wt% or 20 - 25 wt%) of hydroxypropylated starch (including hydrolyzates of hydroxypropylated dextrin such as hydroxypropylated starch) or other modified starch (or other modified polysaccharides), 15 - 60 wt% or 15 - 55 wt% (particularly 25 - 45 wt% or 30 - 45 wt%) of sucrose (saccharose) or other low molecular weight saccharides, and 30 - 65 wt% or 30 - 60 wt% (particularly 35 - 47 wt% or 35 - 45 wt%) of water.

Advantages of the Invention

[0019] For the liquid paste, the viscosity during use is appropriate, the adhesive force after pasting is sufficient, and wrinkling can be suppressed.

Modes for Carrying Out the Invention

[0020] The following describes preferred embodiments of the liquid paste for paper of the present invention. However, those that can obtain equivalent effects by replacing some with other equivalents or equivalent configurations also belong to the scope of the present invention.

[0021] The solid content (non-volatile content) of the liquid sizing agent for paper, excluding water, can be 30 to 72%, more preferably 35 to 70% or 40 to 65%. More specifically, the upper limit of the solid content can be 72%, 71%, 70%, 69%, 68%, 67%, 66% or 65%. Also, the lower limit of the solid content can be 42%, 41%, 40%, 39%, 38%, 37%, 36% or 35%. Also, in some cases, the lower limit of the solid content can be 34%, 32% or 30%. Further, 90% or more, 93% or more, 95% or more or 98% or more of the solid content consists of processed (chemical) starch (including dextrin) and low molecular weight saccharides.

[0022] The range of the solid content can vary depending on the type of low molecular weight saccharides described below, particularly the solubility in water at room temperature (e.g., 20 °C, 25 °C or 30 °C). For example, for sucrose (211.5 g / 100 g water) and fructose (388 g / 100 g water) with high solubility at 20 °C, they can be used in the above wide range, or in some cases, a slightly wider range than the above. However, when using low molecular weight saccharides with lower solubility at 20 °C than sucrose, etc., for example, when using maltose (101 g / 100 g water), glucose (88 g / 100 g water), etc., the preferred range of the solid content can be narrower, and particularly the upper limit value can be lower. For example, when using maltose, glucose, etc., the upper limit of the preferred range of the solid content is less than 70% by weight, and can be, for example, 69%, 68%, 67%, 66%, 65%, 64%, 63%, 62%, 61%, or 60%. On the other hand, when using trehalose (69 g / 100 g water) with even lower solubility at 20 °C, the upper limit value of the solid content can be the same as or even lower than that in the case of glucose, etc. For example, the upper limit of the preferred range of the solid content can be 64%, 63%, 62%, 61%, 60%, 59%, 58%, 57%, 56% or 55%.

[0023] The weight ratio of the low molecular weight saccharide to the water-soluble modified polysaccharide ([weight of low molecular weight saccharide] ÷ [weight of modified polysaccharide]) is, for example, for compound species with a molecular weight of 1000 or less and a molecular weight of 1000exceeding It can be a weight ratio with a compound species. For example, when using certain dextrins or starch syrups, it can be divided into a part belonging to modified polysaccharides and a part belonging to low-molecular-weight saccharides depending on whether the molecular weight is 1000 or less. In addition, as a water-soluble modified polysaccharide, when the molecular weight is low, for example, the weight-average molecular weight (in terms of glucose conversion by GPC using an aqueous DMSO solution) is 20,000 or less or 10,000 or less, the weight ratio of low-molecular-weight saccharides to the modified polysaccharide can be, for example, 0.4 to 3 or 0.5 to 2. Conversely, when using a high-molecular-weight one, for example, the weight-average molecular weight is 500,000 or more or one million or more, the weight ratio of low-molecular-weight saccharides to the modified polysaccharide can be, for example, 4 to 12, 4 to 8 or 4 to 10.

[0024] As the low-molecular-weight saccharide, a sugar alcohol directly derivable from a monosaccharide or a disaccharide can be used. Even when using a sugar alcohol, the solid content range can be the same as described above. In the case of xylitol (50 g / 100 g water), which is a sugar alcohol with 5 carbon atoms, the range of possible solid content can be the same as that of glucose etc. above. Also, in the case of sorbitol (solubility: 220 g / 100 g water), which is a sugar alcohol with 6 carbon atoms, the range of possible solid content can be the same as that of sucrose above.

[0025] As the low-molecular-weight saccharide, or a material containing a low-molecular-weight saccharide, various oligosaccharides can be used. Examples of oligosaccharides include raffinose, maltotriose, galactooligosaccharide, fructooligosaccharide, and lactosucrose. Also, in some cases, molasses or high maltose syrup with a DE (Dextrose Equivalent) value of 40 or more or 45 or more can be used.

[0026] Water-soluble modified polysaccharides can be, for example, etherified starch, oxidized starch, etherified cellulose, oxidized starch, etc., and may also be etherified oxidized starch, esterified oxidized starch, etc. They can also be dextrin, or dextrin with etherification or oxidation added. Etherification here includes hydroxypropylation, hydroxyethylation, methylation, carboxymethylation, etc. Water-soluble modified polysaccharides generally include water-soluble ones among those generally called processed starch (Non-Patent Document 3).

[0027] Processed starch includes, in addition to hydroxyalkylated starch, oxidized starch, acetylated oxidized starch, etc., and further includes various dextrins, equivalent thickening polysaccharides or their hydrolysates, and those obtained by subjecting these to "processing" such as hydroxyalkylation. In particular, among those generally called processed starch (Non-Patent Document 3), they can be non-ionic ones (those not containing acid salts, phosphate groups, etc.). However, in some cases, they may be, for example, acetic acid (acetylated) starch, or those obtained by partially cross-linking dextran, etc.

[0028] "Hydroxyalkylation" in the present application is exactly the same as the description of hydroxypropyl starch mentioned above. That is, it includes hydroxypropylation, hydroxypropyl-methylation, hydroxyethylation, etc. Also, instead of "hydroxyalkylation", etherification such as methylation or carboxylic acid esterification such as acetylation may be carried out. Note that oxidized starch is obtained by introducing a carboxyl group through oxidation using sodium hypochlorite or the like. Here, the degree of etherification such as "hydroxyalkylation" and methylation is, for example, 3 to 10% or 4 to 8% in terms of the molar ratio to the hydroxyl groups of the sugar. Also, the degree of carboxylic acid esterification such as acetylation is, for example, 0.3 to 3%, 0.3 to 2%, 1 to 5% or 1 to 4% in terms of the molar ratio to the hydroxyl groups of the sugar. Furthermore, for oxidized starch, the ratio of the carboxyl groups introduced by the oxidation treatment to the hydroxyl groups in the "starch" before the oxidation treatment can be 0.5 to 10%, 0.5 to 2%, 0.5 to 3%, 1 to 4% or 1 to 7%.

[0029] Typically, hydroxyalkylated starch with a molar substitution degree (MS) of 0.04 to 0.4 is used as hydroxyalkylated starch, and its safety has also been confirmed (Non-Patent Document 2). The production of hydroxyalkylated starch can be obtained, as described in the examples of Patent Document 1, by adding starch to a relatively small amount of aqueous sodium sulfate solution with sodium hydroxide added, reacting, then neutralizing, washing with water, dehydrating, drying, and pulverizing, and then moderately reducing the molecular weight. The reduction of the molecular weight can be carried out using an enzyme or an oxidizing agent such as sodium hypochlorite or hydrogen peroxide. According to Table 1-1 of Patent Document 1, the amylose content of waxy starch is less than 1%, and the amylose content of general potato starch and tapioca starch is around 20%.

[0030] Hydroxyalkylated starch or other modified starches, when used in an appropriate amount with an appropriate molecular weight or within an appropriate viscosity range (30% viscosity), impart an appropriate viscosity to the liquid paste and also impart tackiness immediately after application and adhesiveness after curing. On the other hand, low molecular weight (molecular weight of 1000 or less, 800 or less, or 600 or less) saccharide compounds such as sucrose are considered to not only make it possible to lower the water content but also, by imparting appropriate fluidity to the layer of the liquid paste after application, combine with hydroxyalkylated starch or other modified starches to provide the property of being less likely to wrinkle.

[0031] In a particularly preferred embodiment, the modified starch is hydroxypropylated starch (with a molar substitution degree of 0.04 to 0.4 and a molecular weight of 50,000 to 450,000 or a 30% aqueous solution viscosity of 50 to 1000 mPa·s) that is used as an additive in foods, pharmaceuticals, etc. It exhibits viscosity characteristics similar to gum arabic, is excellent in film-forming properties, and forms a transparent and uniform adhesive layer, so it is preferred.

[0032] As dextrin, those with a DE (Dextrose Equivalent) value of 10 or less and a degree of polymerization of 12 or more can be used, and maltodextrin (DE of about 10 to 20, degree of polymerization of 6 to 10) can also be used. Also, in some cases, materials containing water-soluble modified polysaccharides (molecular weight over 1000) such as those called starch syrup can be used.

[0033] Low molecular weight saccharides are monosaccharides or disaccharides, or sugar alcohols thereof, and in some cases trisaccharides or tetrasaccharides, or oligosaccharides can be used. As the monosaccharides or disaccharides, sucrose and fructose, which have high solubility in water, are preferred, but glucose and xylitol, as well as saccharide compounds having similar solubility thereto, can be used in substantially the same manner. For example, xylose, maltose, trehalose, lactose, raffinose, maltotriose, etc. can also be used. Further, sugar alcohols having at least 4 carbon atoms, particularly 5 or more carbon atoms can be used. Specifically, sorbitol, xylitol, etc. can be used. In some cases, various oligosaccharides (particularly trisaccharides or tetrasaccharides) can be used alone or in admixture with monosaccharides or disaccharides, etc. Oligosaccharides usually have a number average molecular weight of 1000 or less, 800 or less, or 600 or less.

[0034] Sucrose is particularly preferred among low molecular weight saccharide compounds because it is inexpensive and can form a high-concentration aqueous solution. However, maltose, etc. can also be used in place of sucrose or in combination with sucrose. To prepare a liquid paste, for example, a high-concentration (e.g., 53 to 57% by weight) aqueous solution of hydroxyalkylated starch and a high-concentration (e.g., 57 to 63% by weight) aqueous solution of sucrose, etc. can be mixed.

[0035] In a preferred embodiment, the remainder of the liquid paste, excluding hydroxyalkylated starch, or other modified starch (in some cases, modified starch and other thickening polysaccharides) and low molecular weight saccharide compounds such as sucrose, consists essentially of only water. However, salts such as starch or its hydrolyzate, pH adjusters, and preservatives such as polyamino acids can be added as appropriate. In this case, the total amount of these additives can be, for example, 10% by weight or less, 7% by weight or less, 5% by weight or less, or 3% by weight of the liquid paste.

[0036] Here, for thickening polysaccharides other than "modified starch", when the solid content is low (for example, 30 to 45% by weight, 30 to 43% by weight, or 30 to 40% by weight), the viscosity is made within a more preferable range to improve wrinkle resistance (the property of being difficult to wrinkle) and tackiness. As the thickening polysaccharide, particularly preferably a non-ionic one (excluding alginic acid, etc.) can be used. For example, xanthan gum, guar gum, locust bean gum, carrageenan, gum arabic, etc. can be used. In some cases, methyl cellulose, etc. can also be used. The content of the thickening polysaccharide in the liquid paste can be, for example, 0.1 to 5%.

[0037] <Examples, reference examples, and comparative examples of liquid paste, and viscosity> The following reference examples are not outside the scope of the present invention and can also be examples. (1) Modified starch All of the modified starches used were hydrates with a water content of about 6 to 7%.

[0038] (1-1) Hydroxypropylated starch 1 - 3 In most experiments, the following hydroxypropylated starch 1 was used. Also, in a very small number of experiments, the following hydroxypropylated starches 2 - 3 were used. Hydroxypropylated starches 1 - 2 are those obtained by subjecting starch to hydroxypropylation and then adding hydrolysis by enzymatic treatment. The molecular weight is the weight average molecular weight.

[0039]

Table 1

[0040] (1-2) Tapioca maltodextrin 1 - 2 Those derived from tapioca starch, with a DE value of 18 (tapioca maltodextrin 1) and 25 (tapioca maltodextrin 2) were used.

[0041] (1-3) Acetylated oxidized starch 1 - 2 Using tapioca starch (amylose content of about 17%) as a raw material, one with an aqueous solution viscosity of 60 - 80 cps (mPa·s) for a 20% (Dry; on a dry weight basis) aqueous solution obtained by oxidative modification was used. Those with an acetyl substitution degree of 0.02 or more (oxidized acetylated starch 1) and those with an acetyl substitution degree of 0.012 or more (oxidized acetylated starch 2) were used. That is, those in which about 1.3% or more and about 0.4% or more of the hydroxyl groups of the starch were converted to acetyl groups were used.

[0042] (2) Low - molecular - weight saccharides In most experiments, sucrose (SU) (purity 99.5% or more) was used. Also, instead of sucrose, glucose (grape sugar), a monosaccharide compound, xylitol (with 5 carbon atoms), a sugar alcohol, trehalose, a disaccharide compound, and galactooligosaccharide (4’ - galactosyllactose), a trisaccharide compound, were used. For all of these, those with a purity of 99.5% or more were used.

[0043] (3) Preparation of liquid paste I (3 - 1) Examples 1 - 8 A 55 - weight% aqueous solution of the above - mentioned hydroxypropylated starch 1 (HPS) and a 60 - weight% aqueous solution of sucrose (SU) were mixed at a ratio of 1:1 to 1:7 to obtain liquid pastes respectively. Also, liquid pastes were prepared by mixing a 45 - weight% aqueous solution and a 50 - weight% aqueous solution of the above - mentioned hydroxypropylated starch with a 60 - weight% aqueous solution of sucrose at a ratio of 1:1. These are summarized in Table 2 below.

[0044]

Table 2

[0045] (3 - 2) Viscosity measurement Using a BL-type viscometer (TOKI SANGYO BL II), the rotational viscosity of the liquid paste was measured at 25 °C using a No. 4 rotor. At this time, it was placed in a vial (Maruemu container No. 7: 14 mL, φ21.0×φ21.4×55.5 (mm)) so that the liquid level height was 6 cm, held in a constant temperature water bath for 30 minutes or more, the rotor was set in the liquid, and the value 30 seconds after the start of rotation was read to obtain the converted value (mPa / s). Also, in this way, measurements were continuously performed in the order of 60 rpm → 30 rpm → 12 rpm → 6 rpm. The results are shown in Table 2.

[0046] According to the results in Table 2, in Examples 1 to 5, the rotational speed dependence of viscosity (shear rate dependence; thixotropy) was as small as that of Comparative Examples 1 and 2 which are conventional products. On the other hand, in Example 8, the rotational speed dependence of viscosity was large. However, the viscosity at low rotational speeds was not so small.

[0047] (3-3) Comparative Example 1 As Comparative Example 1, "Arabic Yamato Standard" (Yamato Corporation), which is one of typical commercially available liquid pastes, was used. This liquid paste, like most other commercially available liquid pastes, consists of a viscous aqueous solution of polyvinyl alcohol (PVA).

[0048] (3-4) Comparative Example 2 As Comparative Example 2, the above-mentioned "non-wrinkling paste" (Fuyigomi Industry Co., Ltd.) was used. This liquid paste has polysaccharides (aqueous system) as the main component and a water content of about 30% by weight.

[0049] (4) Preparation of Liquid Paste II (Examples 9 to 26, and Reference Examples 1 to 5) In the following Examples 9 to 15, as shown in Table 4 below, an aqueous solution of the above hydroxypropylated starch 1 (HPS) and a 60% by weight aqueous solution of sucrose (SU) were mixed to obtain liquid pastes respectively.

[0050]

Table 3

[0051] In Examples 16 to 26 shown in Table 6 and Reference Examples 1 to 5 shown in Table 7 below, an aqueous solution of the above hydroxypropylated starch 1 (HPS) and an aqueous solution of sucrose (SU) were mixed so as to have the weight compositions shown at the left ends of Table 6 and Table 7, respectively, to obtain liquid glues.

[0052] (5) Preparation of Liquid Glue III (Examples 27 to 31, Reference Examples 9 to 12) In Examples 27 to 31 and Reference Examples 9 to 11 shown in Table 8 below, various low-molecular-weight saccharides were used instead of sucrose (SU), and an aqueous solution of the above hydroxypropylated starch 1 (HPS) and an aqueous solution of low-molecular-weight saccharide (LS) were mixed so as to have the weight compositions shown at the left ends of Table 8, respectively, to obtain liquid glues.

[0053] (6) Preparation of Liquid Glue IV (Examples 32 to 33, Reference Examples 13 to 14) In Examples 32 to 36 and Reference Examples 13 to 14 shown in Table 9 below, various "modified starches" (PS; processed starch) were used instead of hydroxypropylated starch 1 (HPS), and an aqueous solution of "modified starch" and an aqueous solution of low-molecular-weight saccharide were mixed so as to have the weight compositions shown at the left ends of Table 8, respectively, to obtain liquid glues.

[0054] <Performance Evaluation Method> (1) Wrinkling property (property of being difficult to wrinkle) The glue was uniformly applied to the entire surface of the coating paper with a bar coater No. 26 (approximate film thickness of 60 μm when wet) and pasted onto the backing paper. Then, the degree of wrinkling was confirmed by a sensory test by a plurality of panelists. The wrinkling evaluation was performed after leaving it for 1 hour after pasting, that is, after drying until the moisture disappeared. Specifically, the evaluation was performed as follows. However, in the experiments of various modified starches in Table 9 (Examples 32 to 36 and Reference Example 13),

[0055] · Coating paper: General-purpose white printer paper (A4 PPC, copy paper), basis weight 64 g / m 2, paper thickness 0.09 mm, Kokuyo's "KB39N". It was used after being cut into a 15×3 cm rectangle. · Mounting board: Campus notebook (Kokuyo's "No. 3HAN").

[0056] · Sensory test: Entrusted to an external testing institution and evaluated by 5 panelists (men and women in their 30s and 40s) according to the following criteria. There were cases where there was a one-step variation among the panelists. In this case, the evaluation by the majority of the panelists was adopted. ◎ Almost no wrinkles at all (no wrinkles or paper deflection can be felt) 〇 Visible deflection is slightly noticeable visually, similar to Comparative Example 2 ("non-wrinkling paste") 〇- Slightly inferior to Comparative Example 2, but significantly superior to Comparative Example 1 (PVA aqueous solution) △ Better than Comparative Example 1 (PVA aqueous solution), but wrinkles can be visually observed × Wrinkles are significantly visible

[0057] (2) Tackiness The paste was evenly applied to the entire surface of the flap of the envelope using a cotton swab, and the flap was closed and bonded. It was confirmed whether the flap part floated or not. · Envelope: General-purpose white envelope (long size No. 3, 120×235 mm), basis weight 100 g / m 2 , paper thickness 0.10 mm ◎ The flap part does not float × The flap part floats

[0058] (3) Thread-drawing property 0.5 ml of the paste was placed on a plate made of ABS resin, and the ease of thread formation was observed when a rubber plate was repeatedly pressed against and separated from it, and evaluated according to the following criteria. ◎ No thread-drawing occurs at all 〇 Thread-drawing does not occur unless it is repeated 5 times or more × Thread-drawing occurs within 5 or fewer repetitions

[0059] (4) Gelation resistance It was sealed in a 200 mL sample bottle and left for 3 months, after which the presence or absence of turbidity was evaluated as follows. ◎ No turbidity occurred at all and it remained completely colorless and transparent. 〇 Slight turbidity occurred, but no change in viscosity was observed. × Turbidity occurred and the viscosity increased by 10% or more.

[0060] <Performance evaluation results> The results of the performance evaluation related to the preparation I of liquid paste (Table 2) are summarized in Table 4 below. As known from Table 3 below, in Examples 2 to 8, good results were obtained regarding wrinkle resistance, tackiness, transparency (storage stability), and thread-drawing property. In particular, in Example 4, although not shown in the evaluation of Table 3, the most excellent results were obtained sensually regarding wrinkle resistance and thread-drawing property.

[0061] When comparing the evaluation results of Examples 2 to 3 and 5 to 8 with the evaluation results of Comparative Example 2, the wrinkle resistance was equivalent. However, in terms of thread-drawing property, the examples of the present application were clearly superior.

[0062]

Table 4

[0063]

Table 5

[0064]

Table 6

[0065]

Table 7

[0066]

Table 8

[0067]

Table 9

[0068] As described above, according to the embodiments of the present application, good results were obtained in all aspects of wrinkle resistance, tackiness, transparency (storage stability), and thread-drawing property. In particular, good wrinkle resistance (the property of being difficult to wrinkle) was obtained, along with low thread-drawing property, that is, the property of having little stickiness during use. In addition, the liquid glues of each example and each reference example shown in Tables 4 to 9 had viscosities that were generally within the viscosity range of the examples shown in Table 3.

[0069] According to the results shown at the right end of Table 3 above, it was confirmed that good gelation resistance was obtained. Also, according to the results of Tables 3 to 7 above, good results were obtained in all aspects of wrinkle resistance, tackiness, and thread-drawing property within the range of the weight ratio of sucrose to hydroxypropyl starch (SU / HPS) of 0.50 to 11.0 and the range of solid content of 40 to 70% by weight.

[0070] In particular, referring to the results of the reference examples shown in Table 7, although it varies somewhat depending on the conditions, it was judged that the upper limit of the solid content would be about 70% by weight and the lower limit would be about 40% by weight or 35% by weight. Also, it was judged that the upper and lower limits of the weight ratio of sucrose to hydroxypropyl starch (SU / HPS) would be about 0.50 and about 11 when the solid content was close to the lower limit. In addition, when the solid content was around 60% by weight, which was presumed to be the most optimal, a slightly wider weight ratio (SU / HPS) was considered to be possible.

[0071] According to the results of Table 8 above, when any of glucose, trehalose, galactooligosaccharide, and xylitol were used as low molecular weight saccharides, good results were obtained in all aspects of wrinkle resistance, tackiness, and thread-drawing property. Also, as a result of observations over several weeks, the transparency (storage stability) was also good. However, as a result of preliminary experiments, it was presumed that the upper limit of the preferable range of the solid content would be less than 70% by weight.

[0072] According to the results of Examples 32 to 33 shown in Table 9 above, even when tapioca maltodextrin was used instead of hydroxypropylated starch, good results were obtained in terms of all aspects of wrinkle resistance, tackiness, and thread-dragging property. At this time, the weight ratio (SU / HPS) of sucrose to "modified starch" and the solid content were set within the range considered to be optimal.

[0073] According to the results of Examples 34 to 36 shown in Table 9 above, even when "hydroxypropylated starch 2" with a smaller average degree of polymerization (for example, weight-average degree of polymerization) was used as the hydroxypropylated starch, good results could also be obtained. On the other hand, according to the results of Comparative Examples 13 to 14 shown in Table 9 above, almost good results could be obtained even when general acetylated oxidized starch was used.

Claims

1. The solid content is 40 to 70% by weight, and the solid content consists essentially of a water-soluble modified polysaccharide and a low-molecular-weight saccharide. The weight ratio of the low-molecular-weight saccharide to the modified polysaccharide ([weight of low-molecular-weight saccharide]÷[weight of modified polysaccharide]) is 0.4 to 12, and the viscosity (BL viscometer, 6 rpm) is 500 to 10,000 mPa / s. When the water-soluble modified polysaccharide is dextrin, its content is less than that of the low-molecular-weight saccharide. The low-molecular-weight saccharide has a molecular weight of 1000 or less, and the water-soluble modified polysaccharide has a molecular weight exceeding 1000. It is a liquid sizing agent for paper.

2. The liquid sizing agent for paper according to claim 1, wherein the water-soluble modified polysaccharide is at least one of starch derivatives, cellulose derivatives, and dextrin.

3. The liquid sizing agent for paper according to claim 2, wherein the water-soluble modified polysaccharide is at least one of hydroxyalkylated starch, oxidized starch, oxidized acetylated starch, methylated starch, carboxymethylated starch, acetylated starch as starch derivatives, methylated cellulose, hydroxyalkylated cellulose, and carboxymethylated cellulose as cellulose derivatives, and dextrin.

4. The liquid sizing agent for paper according to claim 3, wherein the water-soluble modified polysaccharide is at least one of hydroxyalkylated starch, oxidized starch, methylated starch, oxidized acetylated starch, and dextrin, and the hydroxyalkylation here is hydroxypropylation or hydroxyethylation.

5. The liquid sizing agent for paper according to any one of claims 1 to 4, wherein the low-molecular-weight saccharide is at least one of monosaccharides, disaccharides, their sugar alcohols, and oligosaccharides.

6. The liquid sizing agent for paper according to claim 5, wherein the low-molecular-weight saccharide is at least one of sucrose, fructose, glucose, xylose, maltose, trehalose, xylitol, sorbitol, lactose, raffinose, maltotriose, galactooligosaccharide, fructooligosaccharide, and lactosucrose.

7. The liquid sizing agent for paper according to claim 5, which consists of an aqueous solution containing 4 to 45% by weight of a water-soluble modified polysaccharide, 15 to 60% by weight of a low-molecular-weight saccharide, and 30 to 65% by weight of water.

8. The water-soluble modified polysaccharide contains hydroxyalkylated starch, and the hydroxyalkylated starch has a molar substitution degree (MS) of 0.04 to 0.

4. The liquid sizing agent for paper according to claim 3.

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