JP2010174095A - Adhesive for corrugated board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new adhesive for a corrugated board, which contains no formalin, gives excellent water-resistant adhesion, and has good viscosity stability. <P>SOLUTION: The adhesive for the corrugated board is prepared by blending a water-resistant additive with an aqueous suspension base which contains non-gelatinized starch to develop corrugated board top adhesion by heat gelation and gelatinized starch as a carrier component, wherein a polyamide epoxy resin is formulated as the water-resistant additive, and all or a portion of the gelatinized starch is substituted by natural thickening polysaccharide (except starch) which can be a food additive. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is based on an adhesive based on an aqueous suspension containing ungelatinized starch that causes the adhesion of corrugated board tops by heat gelatinization and gelatinized starch (α starch) as a carrier component, The present invention relates to an adhesive for corrugated cardboard.

  In the following description, the blending unit is a mass unit unless otherwise specified.

  As the corrugated cardboard adhesive, starch-based adhesives are mainly used from the comprehensive viewpoints such as food safety, bonding workability and cost. These starch-based adhesives for corrugated cardboard are prepared by a 2-tank system (Steinhole system), a 1-tank system, a premix system, or the like.

  With the recent expansion of the use of corrugated cardboard for packaging frozen foods and fruits and vegetables, high water-resistant adhesiveness and further food safety have been required for corrugated cardboard adhesives.

As a water resistance technology for a corrugated cardboard adhesive (a technology for imparting water resistance adhesion), for example, Non-Patent Document 1, pages 588 to 589,
“With the expansion of the use of corrugated cardboard, water-resistant adhesion is required for packaging frozen foods and fruits and vegetables. Water resistance is achieved by adding 2-7% formaldehyde condensates such as urea, resorcinol, and acetone. Moreover, the effect can be increased by using a high amylose starch in the carrier part. "

  The water resistance technique is a technique for blending a formaldehyde condensate into the above-mentioned adhesive base (glue solution) prepared from general-purpose starch to make a water-resistant adhesive, and / or water-resistant starch as an adhesive base. This is a technique using a material prepared from (high-amylose starch).

  However, these formalin condensation resins contain residual formalin. Formalin is feared to be carcinogenic and has been designated as a Class 1 Designated Chemical Substance by the PRTR Law.

  For this reason, cationic water-soluble polyamide resin (for example, Patent Document 1), thermosetting resin (polyamide) obtained by reacting polyamide and epihalohydrin (epichlorohydrin) as water resistance technology without using formalin-based condensation resin Proposal of water resistance technology for corrugated cardboard adhesives that uses epoxy resin) (for example, Patent Documents 2 and 3) and ethylene-α, β-ethylenically unsaturated carboxylic acid copolymer resin emulsion (Patent Document 4) Has been.

  However, the present inventors blended a water-resistant agent based on a polyamide resin not containing formalin described in the above Patent Documents 1 to 4 and the like to give a predetermined water-resistant adhesive property to the adhesive for cardboard ( It was found that when trying to make it water resistant, the viscosity of the adhesive suddenly increased immediately after mixing, and high-speed bonding during the production of corrugated cardboard could not be stabilized and was not suitable for practical use. On the other hand, if the blending amount of the water-resistant agent is reduced in order to suppress an increase in viscosity, it is difficult to obtain necessary water-resistant adhesiveness.

  As an adhesive for corrugated cardboard containing a polyamide epoxy resin as a water resistant agent, a technique intended for viscosity stability has been proposed in Patent Document 5 relating to the same application as the applicant of the present application. It does not affect the patentability of the present invention.

  Patent Document 6 is a prior art document describing a polyamide epoxy resin used in the present invention.

"Starch Science Handbook", supervised by Jiro Mikuni, 1977 edition, published by Asakura Shoten Co., Ltd .: pp. 588-589

JP 09-316413 A (summary etc.) Japanese Patent Publication No. 35-3547 (claims, etc.) JP-A-55-54371 (summary etc.) JP-A-10-88090 (summary) Japanese Patent Laying-Open No. 2005-226011 (abstract, paragraph 0046) JP 2005-15811 A (summary etc.)

  In view of the above, an object of the present invention is to provide a novel non-formalin type adhesive for corrugated board that is excellent in viscosity stability and excellent in water-resistant adhesion.

  In order to solve the above problems, the present inventors have devised an adhesive for corrugated board having the following constitution as a result of intensive studies.

An adhesive for corrugated board, which is based on an aqueous suspension containing ungelatinized starch that causes adhesion to the top of the corrugated board by heat gelatinization and gelatinized starch as a carrier component, and is formulated with a water-resistant agent In
Polyamide epoxy resin is blended as the water-proofing agent, and all or part of the gelatinized starch is replaced with a natural thickening polysaccharide to which food can be added (except for “starch”; the same applies hereinafter). Features.

  That is, the starch-based adhesive for corrugated board contains natural thickening polysaccharides (excluding starch) to which food can be added instead of gelatinized starch (α starch), and may contain residual formalin. Polyamide epoxy resin not blended as a waterproofing agent.

  It is presumed that the mechanism for improving the viscosity stability by the corrugated board adhesive of the present invention is as follows.

  1) Since all or part of gelatinized starch (α-starch) as an adhesive-based carrier component is replaced with thickening polysaccharide, there is substantially or little gelatinized starch that easily reacts with polyamide epoxy resin. . For this reason, even if a polyamide epoxy resin is blended, a rapid increase in viscosity hardly occurs and the viscosity stability is excellent.

  2) When a thickening polysaccharide having heat-gelling ability is used, the thickening polysaccharide has low reactivity with the polyamide epoxy resin at room temperature (when not heated), but at the time of bonding (when heated) ), The reactivity with the polyamide epoxy resin is increased by gelation. Therefore, excellent water-resistant adhesiveness can be imparted to the starch-based adhesive.

  According to the present invention, it is possible to provide an adhesive for corrugated cardboard that does not contain harmful residual formalin, has excellent viscosity stability, and excellent water-resistant adhesion, improves the working environment at the time of corrugated board manufacture, and improves food safety in products. Contributes to improvement.

  In addition, the starch-based adhesive for corrugated cardboard of Patent Document 5 contains a polyamide epoxy resin as a water-proofing agent (crosslinking agent), and sodium alginate, guar gum, locust bean gum, etc. for thickening / viscosity adjustment. Of natural thickening polysaccharides (see claim 1, paragraph 0042).

  However, the thickening polysaccharide in Patent Document 5 must contain at least one of aluminate and silicate as a thickening aid in order to stabilize the viscosity of the adhesive (see claim 1). Furthermore, it is premised on containing gelatinized starch (α starch) which is a carrier component, which is different from the present invention (see paragraph 0062, Example 1, etc.).

  That is, as in the present invention, viscosity thickening in a corrugated cardboard adhesive is not planned with only thickening polysaccharide, and further, the amount of gelatinized starch (α starch) is not reduced or not planned. . In the compounding quantity with respect to 100 parts of ungelatinized starch of thickening polysaccharide, this is 0.5-10 parts in this invention, In patent document 6, 0.05-0.4 part (paragraph) In addition, in the present invention, the amount of gelatinized starch to 100 parts of non-gelatinized starch is 2 parts or less, whereas in Patent Document 6, for example, about 3 in Example 1 Part (100 × 8.13 / 255.6).

  Note that Patent Document 5 does not aim at improving water-resistant adhesion, and suggests that viscosity stability is lacking when the amount of the crosslinking agent is increased in an attempt to improve water-resistant adhesion. (Paragraph 0075 Table 1 Example 6 and Paragraph 0074).

  Hereinafter, embodiments of the adhesive for corrugated board of the present invention will be described.

  Basically, the corrugated cardboard adhesive of the present invention includes 1) starch as a main component of the adhesive, 2) polyamide epoxy resin as a water-resistant agent, and 3) food-addable natural as a substitute for gelatinized starch. The thickening polysaccharide (excluding starch) is essential.

  (1) Examples of the starch include corn starch (including dent, waxy, and high amylose), tapioca starch, potato starch, sweet potato starch, wheat starch, sago starch, and various derivatives of these starches, such as etherification and ester. , Grafted, cross-linked, acid-treated, oxidized starch, and the like processed by existing processing methods. Moreover, what combined these starches can also be used.

  (2) The polyamide epoxy resin is not particularly limited as long as it can crosslink with starch and impart water-resistant adhesion to the corrugated adhesive.

For example,
1) Polyamide polyamine obtained by dehydration condensation of polyalkylene polyamine and dibasic carboxylic acid or derivative thereof described in Patent Document 1, or polyamide urea obtained by dehydration condensation of polyalkylene polyurea and dibasic carboxylic acid or derivative thereof Obtained by a method of adding an epihalohydrin to cationization,
2) A polyamide resin obtained by condensing an addition reaction product of an acrylate ester and a diamine or a polyalkylene polyamine described in Patent Documents 2 and 3 or the like, with an epihalohydrin added, or a combination of caprolactam and a polyalkylene polyamine A polyamide resin obtained by condensing a ring-opening adduct with a dibasic acid or an acrylate ester to which an epihalohydrin is added,
3) (I) (A) (a) Both-end carboxylic acid compound having a polyalkylene glycol residue or a polycarbonate diol residue described in Patent Document 5 and (b) a dicarboxylic acid containing an aliphatic or aromatic polyvalent carboxylic acid The compound and (B) organic diisocyanate are reacted at a use ratio such that carboxyl group / isocyanate group (molar ratio)> 1, and (II) epoxy resin is converted to epoxy group / A modified polyamide epoxy resin obtained by reacting at a use ratio such that the carboxyl group (molar ratio) ≧ 1,
And so on.

These are preferably water-soluble, but can also be used as an aqueous emulsion. The compounding amount of the polyamide epoxy resin can be set from the range of 1 to 30 parts with respect to 100 parts of starch solids depending on the required water-resistant adhesion, but from the viewpoint of water-resistant adhesion, 5 to 25 parts, Is preferably 8 to 20 parts, more preferably 9 to 20 parts. If the blending amount of the polyamide epoxy resin is too small, it is difficult to obtain the required water-resistant adhesiveness. Conversely, if the blending amount is too large, the viscosity becomes too high and the viscosity stability is lacking.
(3) The thickening polysaccharide is not particularly limited as long as it is naturally derived (excluding starch) to which food can be added. The reason why the food can be added is limited from the viewpoint of food safety. That is, the thickening polysaccharide does not cause a problem even if the cardboard in use wets and exudes and comes into direct contact with the package (food).

  Sap-derived arabic gum, tragacanth gum, beans seed-derived guar gum, locust bean gum, arabic gum, etc. may be used, but the following seaweed-derived and microbial-produced ones are difficult to enzymatically degrade and adhere to the product (corrugated cardboard) over time. It is difficult to cause deterioration in properties, and furthermore, it is difficult to cause variations in viscosity when used as an adhesive (glue solution).

  In addition, derivatives (etherification, esterification, etc.) of these thickening polysaccharides may be used, and one or two or more may be used in appropriate combination.

Seaweed origin: alginic acid, carrageenan, agar, etc.
From microbial production: xanthan gum, gellan gum, curdlan, etc.

  Among these, those having a gelling ability such as gellan gum and curdlan or carboxypolysaccharide (gel body strength is relatively high) are preferable. Furthermore, gellan gum which is a carboxyl polysaccharide and has heat gelation ability is most preferable. Here, the heat gelling ability refers to a property of gelation at a temperature equal to or higher than normal temperature (usually 30 ° C., desirably 50 ° C.). This thickening polysaccharide has a gelling ability by heating, so that it has low reactivity to the polyamide epoxy resin before bonding (at room temperature) and gels (amorphizes) only during bonding (at heating) to form a polyamide epoxy resin. The reactivity to becomes higher. For this reason, when corrugating the cardboard, the thickening polysaccharide is gelled, which increases the viscosity of the top adhesive and improves the high-speed bonding property, and also reacts with the polyamide epoxy resin to improve the water-resistant adhesion. I can expect.

  0.5-10 parts are preferable with respect to 100 parts of starch solid content, and, as for the compounding quantity of the said thickening polysaccharide, 1.5-5 parts are more preferable. If the blending amount of the thickening polysaccharide is too small, there is no effect of thickening and gelling, and it is difficult to perform the substitute action of the gelatinized starch, and if the blending amount is excessive, the viscosity becomes too high and the viscosity stability is improved. Also lacks.

  The method for preparing the corrugated cardboard adhesive in the present invention may be any of the Steinhole method, the premix method, the one tank carrier method, etc., which are usually used as the method for preparing the corrugator starch-based adhesive, and is not particularly limited. .

  In the adhesive for corrugated board according to the present invention, it is desirable to reduce as much gelatinized starch (α starch) as is usually blended and added as the starch of the carrier part in the above-mentioned method for preparing the starch-based adhesive for corrugators. For example, 2 parts or less is preferable with respect to 100 parts of starch solids. It is further desirable not to use it at all. If the amount of gelatinized starch is large, it is presumed that the viscosity stability tends to be lowered.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples. In addition, the following were used for the starch and each chemical | medical agent in a table | surface, respectively.

Corn Starch: Common corn raw material corn starch, manufactured by Nippon Corn Starch Co., Ltd.
Premix starch for water-resistant glue: “Colbon 5000T” (trade name), manufactured by Nippon Corn Starch Co., Ltd.
Gellan Gum: “Kelcogel” (trade name), manufactured by Dainippon Sumitomo Pharma Co., Ltd.
Card Run: “Card Run NS” (trade name), manufactured by Kirin Food Tech Co., Ltd.
Xanthan gum: “Echo gum” (trade name), manufactured by Dainippon Sumitomo Pharma Co., Ltd.,
Polyamide epoxy resin: “Smiles Resin SR-675A” (trade name), manufactured by Sumika Chemtex Co., Ltd.
Modified ketone resin: “Aika Aibon VL-3340” (trade name), manufactured by Aika Industry Co., Ltd.
Phenolic resin: “Phenolite TD-2398A” (trade name), manufactured by DIC Corporation,
<Example 1>
1) 271 g of premix starch containing 259.3 g (100 parts) of corn starch, 7.6 g (2.93 parts) of gellan gum and 4.1 g (1.58 parts) of borax was prepared.

  2) Add 640 mL of water heated to 40 ° C to a 2 L stainless steel mug, add 271 g of the above premixed starch and stir for 5 minutes, and then add caustic soda aqueous solution (6.0 g of solid caustic soda dissolved in 34 mL of water) ) And stirred for 30 minutes to prepare an adhesive base.

  3) 26 g (10 parts) of a polyamide epoxy resin as a water-proofing agent was blended into this adhesive base and stirred for 15 minutes to prepare a corrugated cardboard adhesive.

<Example 2>
A corrugated cardboard adhesive was prepared in the same manner as in Example 1, except that corn starch was 261.5 g (100 parts), gellan gum was 5.4 g (2.07 parts), and polyamide epoxy resin was 39 g (14.9 parts). did.

<Example 3>
A corrugated cardboard adhesive was prepared in the same manner as in Example 1, except that corn starch: 261.5 g (100 parts) and curdlan: 5.4 g (2.07 parts) were used instead of gellan gum.

<Example 4>
A corrugated cardboard adhesive was prepared in the same manner as in Example 1, except that the amount of corn starch was 260.1 g (100 parts) and xanthan gum 6.8 g (2.61 parts) was used instead of gellan gum.

<Comparative Example 1>
1) Add 640 mL of water heated to 40 ° C to a 2 L stainless steel mug, add 271 g of premix starch for water resistant paste, stir for 5 minutes, and then dissolve caustic soda aqueous solution (6.0 g of solid caustic soda in 34 mL of water) The mixture was stirred for 30 minutes to prepare an adhesive base.

  2) 13.5 g (5 parts) of a modified ketone resin as a water resistant agent and 13.5 g (5 parts) of a phenol resin as a water resistant agent were added to this adhesive base, and stirred for 15 minutes to prepare an adhesive for corrugated board. .

<Comparative example 2>
In Comparative Example 1, a corrugated cardboard adhesive was prepared in the same manner as in Example 1 except that the modified epoxy resin / phenol resin was replaced with polyamide epoxy resin: 27 g (10 parts).

<Test method>
Each adhesive (glue solution) prepared above was stored at 40 ° C. with continuous stirring for 24 hours. Over time, 1) paste viscosity, 2) initial adhesive strength, 3 ) The water-resistant adhesive strength was measured.

1) Viscosity measurement After the preparation, the viscosities were measured at 0 minutes (before water resistance agent blending), 15 minutes and 24 hours later. Viscosity was determined as alternative viscosity by measuring the flow-down time with a HODE CUP (National Corrugated Cardboard Industry Association Association certified product).

2) Initial bond strength
Apply a certain amount of adhesive paste (solid content: 6 ± 1 g / m ² ) to the top of a 5 cm x 8.5 cm A flute single-sided cardboard piece (core: 125 g / m ² ), and a liner of the same size Pieces (220 g / m ² ) were pasted together, and the one that was heat-pressed with an iron at 175 ° C. and 850 g for 5 seconds was used as an initial adhesive strength measurement sample, and the initial adhesive strength was measured immediately. The measurement was performed according to JIS: Z-0402.

3) Water-resistant adhesive strength
A flute single-faced cardboard pieces 5 cm × 8.5 cm (water in the core: 125g / m ²⁾ a certain amount of adhesive to Dan'itadaki of (in terms of solid content: 6 ± 1g / m ²⁾ was applied, water liner of the same size Pieces (220 g / m ² ) were bonded together, and then heat-pressed with an iron at 175 ° C. and 850 g for 5 seconds as a sample for measuring water-resistant adhesive strength. This sample was conditioned in air at 20 ° C. and 65% RH for 24 hours, immersed in water at 20 ° C. for 60 minutes, and then measured for water-resistant adhesive strength based on JIS: Z-0402.

<Test results>
Table 1 shows the results of Examples 1 to 4 and Comparative Examples 1 and 2.

  From these results, the adhesive for corrugated board of the present invention using gellan gum as a thickening agent and using a polyamide epoxy resin as a water-resistant agent does not contain formalin, and has an excellent effect on viscosity stability and water-resistant adhesiveness. I understand that it will bring.

Claims (7)

In an adhesive for corrugated cardboard, which is based on an aqueous suspension containing ungelatinized starch that develops adhesion of corrugated cardboard tops by heat gelatinization and gelatinized starch as a carrier component, and is formulated with a water-resistant agent ,
Polyamide epoxy resin is blended as the water-proofing agent, and all or part of the gelatinized starch is substituted with a natural thickening polysaccharide to which food can be added (excluding starch: the same applies hereinafter). Corrugated cardboard adhesive. In a corrugated adhesive based on an aqueous suspension containing ungelatinized starch,
1 to 30 parts by mass of the polyamide epoxy resin, 0.5 to 10 parts by mass of the thickening polysaccharide, and 2 parts by mass or less of the gelatinized starch with respect to 100 parts by mass of the ungelatinized starch. The adhesive for corrugated board of Claim 1 characterized by these.   The polyamide epoxy resin is 5 to 25 parts by mass, the thickening polysaccharide is 1.5 to 5 parts by mass, and the gelatinized starch is 0 parts by mass with respect to 100 parts by mass of the ungelatinized starch. The adhesive for corrugated board of Claim 2 characterized by the above-mentioned.   4. The corrugated cardboard adhesive according to claim 1, wherein the thickening polysaccharide has a heat-gelling ability.   The adhesive for corrugated board according to 1, 2 or 3, wherein the polysaccharide thickener is a microbial product or a seaweed-derived product.   4. The corrugated cardboard adhesive according to claim 1, wherein the thickening polysaccharide is a carboxyl polysaccharide.   The corrugated adhesive according to claim 1, 2 or 3, wherein the thickening polysaccharide is gellan gum.