JP4592299B2 - Starch adhesive for corrugated board - Google Patents

Description

   The present invention relates to an adhesive for corrugated board mainly used for producing corrugated board.

  Here, the starch-based adhesive for corrugated cardboard is a corrugator (corrugated cardboard making machine) prepared by a paste making method such as a so-called Steinhole method, one tank Steinhole method (hereinafter abbreviated as “one tank carrier method”). It is a starch-based adhesive.

 Conventionally, as an adhesive for corrugated cardboard used for the manufacture of corrugated cardboard, a starch based adhesive is mainly used from the comprehensive viewpoint of food safety, adhesive workability, cost and the like.

  Usually, starch-based adhesives for corrugated cardboard contain boron compounds such as borax and boric acid for the purpose of improving adhesion (increasing viscosity). That is, when preparing a starch-based adhesive for corrugated cardboard, a boron compound such as borax or boric acid is added to increase and stabilize the viscosity to ensure adhesion. The function (action) / addition effect of the boron compound in the starch-based adhesive is described as follows.

    1) Form hydrogen bonds with starch to increase and stabilize the viscosity of the paste and improve water retention.

    2) Improves the fluidity (thixotropy) of the paste liquid and works to raise the paste liquid uniformly to the paste roll.

    3) Increases the adhesive strength when the starch gels (gelatinizes), and when the adhesive layer is hot-pressed, it improves the strength of the film formed by starch gelation and has strong adhesive strength Secure.

  Therefore, a boron compound that exhibits such an effect has been considered indispensable for producing a corrugated cardboard sheet at a high speed in a corrugated cardboard adhesive.

  However, this boron compound is now designated as a Class 1 Designated Chemical Substance in the PRTR (Pollution Release and Transfer Register) Act, so it will be avoided in the future due to the complexity of management. There is a possibility that.

  In addition, Class 1 Designated Chemical Substances are substances that are harmful to humans and ecosystems (including ozone depletion) and are widely recognized in the environment (exposed to exposure). . Currently, 354 substances are designated for this.

  In view of the above, the inventors of the present invention have an adhesive performance (viscosity increase / stability) equal to or higher than that of a conventional starch-based adhesive containing a boron compound, even without a boron compound. In order to provide an adhesive for corrugated board (starch adhesive for corrugators), a starch adhesive having the following constitution has been proposed previously (Japanese Patent Application No. 2002-255317: unpublished at the time of filing).

"In starch-based adhesives containing thickeners and thickeners, organic thickeners (except for strong cationic properties) as the thickeners, and silicates as the thickeners. It is characterized by. "
In addition, although it does not affect the invention of this invention, there exists patent document 1 etc. as a prior art document regarding the starch adhesive for corrugated boards which does not reduce or use a boron compound.
JP 2003-201454 A

  In view of the above, the present invention has an adhesive performance (viscosity increase / stability) equal to or higher than that of a conventional starch-based adhesive containing a boron compound, even if the starch-based adhesive does not contain a boron compound. It is an object (problem) to provide an adhesive for corrugated cardboard (starch adhesive for corrugators).

  Another object (problem) of the present invention is to provide an adhesive for corrugated cardboard that can further improve the adhesive performance as compared with the adhesive for corrugated cardboard in the above-mentioned prior application.

  As a result of intensive studies in order to solve the above problems, the present inventors have added a starch cross-linking agent in addition to the polymer flocculant and the thickener, whereby the first and second of the above. The inventors have found that the above problem can be sufficiently solved, and have completed one of the present inventions.

  That is, according to one aspect of the present invention, in the starch-based adhesive for corrugated board containing a thickener and a thickening aid, an organic polymer flocculant (excluding strong cationic property) is used as the thickener, and the thickener is used. It contains at least one of aluminate and silicate as an auxiliary agent, and also contains a crosslinking agent for starch.

  Expressed characteristically, it is a starch-based adhesive containing an organic polymer flocculant (excluding strong cationicity), aluminate and / or silicate and a crosslinking agent for starch as essential agents, Each of the paste liquids has a horde cup viscosity of 20 to 40 seconds in the initial stage before addition of the crosslinking agent, and viscosity stability (degree of change relative to the initial viscosity after 24 hours) within 20% (or within 7 seconds). It is characterized by containing essential drugs.

  In the said invention, it is desirable to select 1 or more types as a crosslinking agent for starch from the group of an epoxy resin type, an ammonium zirconium carbonate type, and a formaldehyde resin type.

  And when using a polyamide epoxy resin or zirconium carbonate ammonium as a crosslinking agent for starch, those compounding quantities are 0.1-15 mass parts and 0.1-2. 0.

  An organic polymer flocculant (excluding strong cationicity), and a starch-based adhesive containing aluminate and optionally silicate, wherein the prepared paste liquid has a horde cup viscosity of 20 to 55 seconds, and The organic polymer flocculant and the aluminate, and further silicate as appropriate are blended so as to show viscosity stability (degree of change relative to the initial viscosity after 24 hours) within 20% (or less than 7 seconds). Features.

  The polymer flocculant is preferably nonionic or weakly anionic, and in particular, a synthetic system that easily obtains a high molecular weight of 9 million or more is desirable.

  As the weak anionic polymer aggregate, a polyacrylic acid type material can be suitably used, and as a nonionic type, a polyacrylamide type material can be suitably used.

  The polymer flocculant may have a viscosity average molecular weight of 300,000 or more, but is preferably 9 million or more. This is because the higher the molecular weight, the greater the thickening effect and the better the viscosity stability.

  In the above, the aluminate or silicate is preferably sodium aluminate and sodium silicate, respectively. Compared to other aluminates or silicates, it has excellent viscosity stabilizing action.

  In addition, in the prior application invention, the present inventors have found that the first problem can be solved even if silicate is replaced with aluminate as a thickening aid, and for corrugated board having the following configuration. I came up with a starch-based adhesive.

  An organic polymer flocculant (excluding strong cationicity), and a starch-based adhesive containing aluminate and optionally silicate, wherein the prepared paste liquid has a horde cup viscosity of 20 to 55 seconds, and The organic polymer flocculant and the aluminate, and further silicate as appropriate are blended so as to show viscosity stability (degree of change relative to the initial viscosity after 24 hours) within 20% (or less than 7 seconds). Features.

  In the present invention, desirable embodiments of the organic polymer flocculant, aluminate, silicate and the like used are the same as described above.

  And it is desirable to apply the starch adhesives of these inventions to corrugated adhesives that require viscosity stability.

Detailed description of the configuration

Hereinafter, the configuration of the present invention will be described in detail. In the following description, “part” means “part by mass” unless otherwise specified.
One of the starch-based adhesives for corrugated board of the present invention (starch-based adhesive for corrugators; paste liquid) is an organic polymer flocculant (hereinafter referred to as a thickener) that is a thickener for starch without adding a boron compound. "Polymer flocculant": excluding strong cationicity), aluminate and / or silicate as a thickening aid, and starch crosslinking agent as essential agents.

  The prepared paste solution has an initial viscosity before addition of the crosslinking agent (hode cup viscosity): 20 to 55 seconds (desirably 20 to 40 seconds, more desirably 25 to 35 seconds), and viscosity stability (24 hours relative to the prepared initial viscosity). The essential drug is formulated so as to show a later degree of change within 20% (preferably within 10%) (or within 7 seconds, preferably within 4 seconds).

  The starch used in the present invention is not particularly limited, and may be starch used in a Steinhole method, a premix method, a one-tank carrier method, or the like that is usually used as a method for preparing a starch adhesive for corrugators.

  That is, starches such as corn starch (including high amylose corn starch and waxy corn starch), potato, tapioca, wheat, sweet potato, etc., and oxidation, acid treatment, etherification, esterification, grafting, cross-linking treatment of these, or their Chemically modified starch that has been subjected to treatment such as a combination, those obtained by combining these starches, and starch obtained by pregelatinizing the starch can be used.

  Examples of the polymer flocculant include the following.

  Here, weak anionic / cationic means an aggregating agent having a high nonionic group content in anionic / cationic, and strong cationic / anionic means content of anionic group / cationic group. Means a flocculant with a high value, and those intermediate flocculants are called medium anionic and cationic.

  The guidelines for the above strong, medium and weak are usually set as follows.

When the number of moles of the cationic (or anionic) moiety in the structural formula is y and the number of moles of the nonionic moiety is x,
Mole% of cation degree (anion degree) = {y / (x + y)} × 100
Means the following numerical ranges.

Strong cation (or strong anion): 100 to 60 mol%
Medium cation (or medium anion): 60-30 mol%
Weak cation (or weak anion): 30 mol% or less <Synthetic polymer flocculant>
<Nonionic> Polyacrylamide, Polyethylene oxide <Anionic> Sodium polyacrylate (or acrylamide-sodium acrylate copolymer), Partially hydrolyzed polyacrylamide, Sulfomethylated polyacrylamide,
<Cationicity: Excluding strong cationicity. > Polyaminomethylacrylamide, polyvinylimidazoline, polyaminoalkyl (meth) acrylate, polyvinylpyridium halide, polydimethyldiallylammonium halide, ionene-based,
<Amphoteric> Acrylamide, (meth) acrylic acid ester, acrylic acid polymer (having both cationic and anionic groups in the molecule)
More specifically, those marketed by Organo Co., Ltd. under the following trade names can be used.

"Olflock OA-23": weakly anionic, polyacrylic acid polymer (M = 111 to 12 million)

・ "Olflock ON-2": nonionic, polyacrylamide polymer (M = 11 to 12 million)

"AP-1": Medium anionic, polyacrylic acid polymer (M = 11 to 12 million)

・ "Olflock OX-432": Amphoteric, polyacrylic ester polymer (M = 5 to 7 million)

<Natural polymer flocculant>
Dextrin, sodium alginate, gelatin, guar gum, locust bean gum Any of the above-mentioned polymer flocculants used in the present invention can be used, and among these, polyacrylic acid polymers are preferred. The polyacrylic acid polymer suitably used in the present invention includes various ionic ones such as cationic (excluding strong cationic), anionic and nonionic, and any of them can be used. Of these, those having weak anionic properties are preferred. The reason why the weak anionic property is preferable and the reason for excluding the strong cationic property are as follows.

  Since starch is generally anionic, the paste system is stabilized by an appropriate electrical repulsion with a weak anionic polymer flocculant. On the other hand, in the case of strong cationicity, it easily aggregates with the starch molecules due to electric attractive force (uniform starch gelatinization is inhibited), and the paste liquid system becomes unstable. In addition, a polymer flocculant such as inorganic polyferric sulfate does not have a thickening action, and instead causes a decrease in viscosity.

  The polyacrylic acid polymer used in the present invention has a molecular weight of 3 million to 20 million, among which a molecular weight of 9 million or more (preferably 10 million to 15 million) is suitable.

  As the aluminate, sodium aluminate, potassium aluminate and the like can be suitably used, and as the silicate, aluminum silicate, calcium silicate, sodium silicate, potassium silicate and the like can be suitably used. Of these, sodium salts are particularly preferably used. This is because it is excellent in action as a thickening aid, particularly in viscosity stabilizing action.

  As the crosslinking agent, an epoxy compound (polyamide epoxy resin or the like), ammonium zirconium carbonate, a formaldehyde resin (ketone resin or the like) can be used, and among them, a polyamide epoxy resin is preferable.

  This is because the initial adhesive strength and the viscosity stability are excellent. The crosslinking agent used in the present invention also promotes water resistance of starch, and can be expected to improve the water resistance of the adhesive layer.

  At this time, the compounding amount of each essential drug differs depending on the type of each drug and the compounding amount of other drugs.

  For example, in the case of a weak anionic polymer flocculant, it is 0.05-0.4 part with respect to 100 parts of starch (solid content), desirably 0.2-0.35 part. If the amount of the polymer flocculant is too small, the thickening effect is small, and if it is excessive, the viscosity of the paste solution is too high and it cannot be used.

  The amount of aluminate and silicate varies depending on the type of salt and whether it is used alone or in combination.

  In the case of using sodium aluminate or sodium silicate alone, the former: 0.5 to 9 parts (preferably 1.0 to 5 parts) and the latter: 0.5 to 9 parts (preferably 1 to 100 parts of starch) .0 to 5 parts).

  In the case of combined use of sodium aluminate and sodium silicate, the total amount is 1.0 to 10 parts (preferably 1.5 to 5 parts) with respect to 100 parts of starch, and the former / the latter = 1/10 to 10/1. (Preferably 1/1 to 6/1).

  Moreover, the compounding quantity of the crosslinking agent for starch also changes with kinds of crosslinking agent, However It is 0.5-10 parts with respect to 100 parts of starch, It is 1-6 parts desirably. When the amount is too small, the effect of improving the initial adhesive strength is small. When the amount is too large, viscosity becomes unstable (Examples 3 and 6).

  In either case, if the blending amount is too small, it is difficult to achieve the effect of stabilizing the viscosity and the effect of improving the initial adhesive strength. Conversely, if the blending amount is excessive, there is a possibility that the thickening becomes unstable.

  The starch-based adhesive of the present invention is based on a starch-based adhesive for corrugators prepared by the Steinhole method, premix method, one tank carrier method, etc., which does not contain a boron compound. And an aluminate and / or silicate and a starch crosslinking agent. These polyacrylic acid polymer, aluminate and silicate are desirably mixed with the main starch in advance. Furthermore, in order to prepare the adhesive of the present invention, no new equipment or change in work procedure is required, and the adhesive can be easily manufactured.

  In addition, by adding (compounding) a thickener (polyacrylic acid polymer), a thickener (aluminate / silicate) and a crosslinking agent to the paste containing the conventional boron compound, It can be used for the purpose of reducing the amount of the elemental compound used.

  In the above-described embodiment, the crosslinking agent is an essential agent. However, in the above-described embodiment, a case where an aluminate and an appropriate silicate are included as a thickening aid without adding a crosslinking agent will be described later. As shown in the embodiment, the first object (object) of the present invention can be achieved.

  Below, in order to confirm the effect of this invention, each paste liquid of the Example / comparative example and the prior art example was prepared as follows.

  In addition, the abbreviation which shows the starch and each chemical | medical agent currently displayed means the following, respectively.

<Starch>
Cornstarch ... Nippon Cornstarch α-starch ... Nippon Cornstarch "Amilox No.1"
<Polymer flocculant>
"OA-23" ... "Olflock OA-23" weak anionic polyacrylic acid polymer <crosslinking agent>
“SR675A”: Polyamide epoxy resin (“Smiles Resin 675A” manufactured by Sumitomo Chemical Co., Ltd.)
“AZ Coat”: Ammonium zirconium carbonate aqueous solution (manufactured by San Nopco: “AZ Coat 5800MT”)
“VL3340”: Modified ketone resin (manufactured by Aika Kogyo Co., Ltd .: “Aika Ivon VL3340”)
<Conventional Example / Comparative Example / Example>
Prepared as follows. In addition, when there was increase / decrease in the additive addition amount, the amount of corn starch was increased / decreased so that the total amount of premix starch was always 271 g.
(Conventional example)
(1) Premix starch containing 239.3 g of corn starch, 27.1 g of α starch, and 4.61 g of borax was prepared.

(2) Add 774 ml of water heated to 40 ° C. in a 2 L stainless steel cup, add the above premixed starch here and stir for 5 minutes to dissolve caustic soda aqueous solution (6.3 g of solid caustic soda dissolved in 36 ml of water). And stirred for 30 minutes to prepare an adhesive for corrugated board.
(Comparative Example-1)
(1) Premix starch containing 266.4 g of corn starch “OA-23” 0.54 g and sodium silicate 4.07 g was prepared.

(2) Put 622 ml of water heated to 40 ° C. into a 2 L stainless steel cup, add the above premixed starch here and stir for 5 minutes to dissolve caustic soda solution (4.9 g of solid caustic soda in 28 ml of water). ) And stirred for 30 minutes to prepare an adhesive for corrugated board.
(Example-1)
(1) Premix starch containing 255.6 g of corn starch, 8.13 g of α starch, 0.54 g of “OA-23”, 5.42 g of sodium aluminate, and 1.36 g of sodium silicate was prepared.

(2) Put 624 ml of water heated to 40 ° C. into a 2 L stainless steel cup, add the above premixed starch here and stir for 5 minutes to dissolve caustic soda aqueous solution (4.0 g of solid caustic soda in 26 ml of water). ) And stirred for 30 minutes to prepare an adhesive for corrugated board.
(Example-2)
In Example-1, a corrugated cardboard adhesive was prepared in the same manner as in Example-1, except that the amount of sodium silicate added was 0 g.
(Comparative Example-2)
In Example-1, a corrugated cardboard adhesive was prepared in the same manner as in Example-1, except that the amount of sodium aluminate added was 27.1 g and the amount of sodium silicate added was 0 g.
(Comparative Example-3)
In Example-1, a corrugated cardboard adhesive was prepared in the same manner as in Example-1, except that the amount of sodium aluminate added was 13.6 g and the amount of sodium silicate added was 2.71 g.
(Example-3)
A corrugated cardboard adhesive was prepared in the same manner as in Example 1 except that 1.36 g of “SR675A” was further added.
(Example-4)
In Example-3, an adhesive for corrugated board was prepared in the same manner as in Example-3 except that the amount of “SR675A” added was 8.13 g.
(Example-5)
In Example-3, an adhesive for corrugated board was prepared in the same manner as in Example-3 except that the amount of “SR675A” added was 16.3 g.
(Example-6)
In Example-3, an adhesive for corrugated board was prepared in the same manner as in Example-3 except that the amount of “SR675A” added was 27.1 g.
(Example-7)
A corrugated cardboard adhesive was prepared in the same manner as in Example 2, except that 8.13 g of “SR675A” was further added.
(Example-8)
An adhesive for corrugated board was prepared in the same manner as in Comparative Example-1, except that 8.13 g of “SR675A” was further added.
(Example-9)
In Example-3, an adhesive for corrugated board was prepared in the same manner as in Example-3, except that 2.71 g of "AZ coat" was added instead of "SR675A".
(Example-10)
In Example-3, an adhesive for corrugated board was prepared in the same manner as in Example-3 except that 13.6 g of "VL3340" was added instead of "SR675A".
<Test method>
The pastes prepared in the above examples and the like were stored at 40 ° C. with continuous stirring for 24 hours, and the following items were tested.

1) Viscosity Measurement Each viscosity after 0 min (before addition of a crosslinking agent), 15 min, and 24 h was measured for the paste solution prepared above. Viscosity was determined as alternative viscosity by measuring the flow-down time with a horde cup (National Corrugated Cardboard Industry Association certified product).

2) Initial adhesive strength Using the glue solution after preparation 1h, a certain amount of adhesive glue solution (solid content) on the top of a 5cm x 8.5cm A flute single-sided cardboard piece (core: 125g / m- ² ) Conversion: 6 ± 1 g / m ⁻² ) applied, liner pieces of the same size (220 g / m ⁻² ) were bonded together, and then the initial adhesive strength measurement was performed by heating and pressing with 175 ° C. and 850 g iron for 5 s. The adhesive layer was immediately peeled off and the initial adhesive strength was measured. The measurement method was a method according to JIS; Z-0402.

3) Purine forming ability 150 g of the paste solution after preparation 1 h is collected in a 200 mL stainless steel cup and heated to a temperature (60 to 65 ° C.) at which the paste solution solidifies while stirring. After standing to cool, the following criteria were used to determine whether or not the pudding-like solidified product could be taken out from the cup.

        ○: Can be easily removed without breaking, Δ: Can be removed but slightly broken.

        X: Difficult to take out by adhering to the cup without solidifying into a pudding.

<Test results>
From Table 1 showing the test results, the following can be understood.

  In the case where an aluminate and / or silicate and also a crosslinking agent are used in combination with the polymer flocculant (Examples 3 to 10), the initial adhesive strength is the case where no crosslinking agent is added (Comparative Example 1, It can be seen that it is further improved as compared to Examples 1 and 2) (Comparative Example 1 and Example 8).

  In addition, even when sodium aluminate is used, if the amount of addition is appropriate (including combined use with sodium silicate), the viscosity increasing effect of the paste solution is the same as when sodium silicate is used. Stabilization is possible, and the adhesive strength higher than that of the conventional example using borax can be obtained (Examples 1 and 2 and Comparative Examples 1 and 2 and 3).

  Further, if an appropriate amount of a crosslinking agent is used in combination, the gelled product of the paste is cured into a pudding like the borosilicate paste (conventional example), and the initial adhesive strength is dramatically improved (Examples 3 to 10).

  Further, it can be seen that when “SR675A” is used as the cross-linking agent, the viscosity stability is excellent and the effect of improving the initial adhesive strength is large as compared with the case where ammonium zirconium carbonate and formaldehyde resin are used.

  In addition, when the polyamide epoxy resin is excessive (“SR675A” of 8% or more), it can be seen that the effect of improving the initial adhesive strength is small and the viscosity stability is deteriorated (Example 6).

Claims (5)

In a starch-based adhesive for corrugated board containing a thickener and a thickening aid, an organic polymer flocculant (excluding strong cationic properties) is used as the thickener, and aluminates and silicates are used as the thickening aid. Containing at least one of the acid salts and a starch crosslinking agent ,
The starch crosslinking agent is a polyamide epoxy resin,
A starch-based adhesive for corrugated cardboard, wherein the polyamide epoxy resin is blended in an amount of 1 to 6 parts by mass with respect to 100 parts by mass of starch solids . 2. The starch-based adhesive for corrugated board according to claim 1, wherein the organic polymer flocculant is nonionic or weakly anionic. The starch-based adhesive for corrugated board according to claim 2, wherein the weak anionic organic polymer flocculant is polyacrylic acid-based or polyacrylamide-based. The starch-based adhesive for corrugated board according to claim 2 or 3, wherein the organic polymer flocculant exhibits a viscosity average molecular weight of 9 million or more. The starch-based adhesive for corrugated board according to any one of claims 1 to 4 , wherein the aluminate is sodium aluminate, and the silicate is sodium silicate.