JP2006150616A - Cardboard for laminate processing and its processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide cardboard for laminate processing capable of preventing the peeling of a printed surface after lamination without lowering laminate adhesiveness at the time of laminate processing. <P>SOLUTION: The cardboard for laminate processing is characterized in that a liquid based on a polymeric compound is controlled so that an absolute dry weight per one side is 0.25-1.0 g/m<SP>2</SP>in the surface treatment of one side or both sides. As the polymeric compound, general starch and polyvinyl alcohol among natural and synthetic polymeric compounds are used to perform surface treatment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a board for laminating used as a packaging material in the food, medical and electronic materials fields, and more specifically, laminated for improving moisture resistance and waterproofing of the packaging material, thereby improving cosmetics and the like. Therefore, the present invention relates to a paperboard for laminating which is printed on a laminated surface after being laminated on one side or both sides.

  Conventionally, packaging materials used in foods such as snacks, frozen foods, liquid containers, etc., medical fields, electronic materials, etc. are often processed with resin on one or both sides, that is, after laminating. Therefore, it is required to have excellent laminating adhesion so that there is no trouble of delamination at the time of printing and molding of packages and cups.

  In addition, it has been demanded that the laminated packaging material has a high cosmetic appearance so as to stir the customer's desire to purchase. Therefore, it has been common to carry out surface treatment to improve the printability of the board for laminating, but conventionally, the surface treatment of the board for laminating is closer to no treatment, so that the laminating adhesiveness is improved. This is well known (for example, see Patent Document 1).

  In pursuit of improved laminating adhesiveness, printing has been performed before laminating to improve cosmetics. However, smoothness and printing quality may be degraded by bringing the surface treatment of the base paper for laminating closer to no processing. After the laminating process, the printing quality is prevented from being deteriorated by printing on a highly smooth laminated surface.

  In addition, gravure printing has been the mainstream of conventional packaging material printing, but the number of lots has been reduced due to increased cost savings. Due to the printing cost advantage, there are more cases of switching from gravure printing to offset printing. Since the offset ink has a high ink tack, a paperboard that is not surface-treated is more likely to cause printing surface peeling (hereinafter referred to as “print blister”) during offset printing after lamination, and is particularly likely to be noticeably generated in a solid portion. As a result, the printing workability and the printing quality are significantly reduced. As described above, due to changes in the printing method and the like, the printability becomes more severe than before, and the paperboard for laminating processing is required to have further high-quality printability.

As a surface treatment on one side or both sides of a conventional offset printing base paper, the coating amount per side is 1.0 g / m ² or more, preferably 2.0 g / m ² or more. However, although the offset printability is very good, the laminating adhesiveness deteriorates, and the laminator pretreatment may not be able to cope with stronger corona discharge or flame treatment, and the operability at the time of laminating processing is significantly reduced. ing.
Japanese Patent No. 2626949

  An object of the present invention is to provide a paperboard for laminating that does not deteriorate the laminating adhesion during laminating and can prevent printing suitability after laminating, specifically, printing blisters.

As a result of intensive studies on the above problems, the present inventor has reached the invention of the board for laminating of the present invention.
In other words, the laminate paperboard of the present invention has a surface treatment in which a liquid containing a polymer compound as a main component is controlled within a certain range, that is, 0.25 to 1.0 g of absolute dry per side. / m is ² which is characterized to manage, as the polymer compound is preferably a starch or at least one of its derivatives and polyvinyl alcohol.

  The paperboard for laminating according to the present invention is provided with a coating layer mainly composed of a polymer compound in one or both sides as required in the normal process in the surface treatment of the paper machine process, thereby reducing the laminate adhesiveness. By applying a surface treatment that is not accompanied, the printability after laminating, in particular, printing blisters can be prevented without degrading the laminating adhesion during laminating, improving the printing workability and improving the final packaging material. The processability and cosmetic properties are further improved. Further, in the surface treatment, the economical effect in production due to the low coating amount and the use of a general polymer compound is great.

  The laminated paperboard of the present invention forms a paper layer on a felt of a paper machine, further laminates the paper layer, and repeats this to produce a laminated paperboard having two or more layers. The laminated paperboard is squeezed with a press part, dried with a pre-dryer part, subjected to the surface treatment according to the present invention with a size press part or a coater part, and re-dried with an after-dryer part. To produce a board for laminating.

  In making the paperboard of the present invention, it is generally a multi-layer papermaking, but of course a single-layer papermaking may be used. In addition, there is no special contract for the pulp used as raw material, for example, chemical pulp such as NUKP, LUKP, NBKP, LBKP, mechanical pulp such as TMP, CTMP, CGP, RGP, GP, SCP, newspaper, magazine, office paper, information Known materials such as waste paper pulp such as paper, cardboard, and paper box can be used alone or in combination of two or more as desired. In the case of multilayer papermaking, each layer may have the same composition or a different composition.

  Like the conventional paperboard, the base paper is made by adding a filler such as clay, white carbon, amorphous silica, talc, titanium oxide, calcium carbonate to the paper as appropriate. In addition, general publicly known papermaking chemicals such as yield improvers, rosin sizing agents, internal sizing agents such as emulsion sizing agents, paper strength enhancers, water resistance agents, and UV protection agents are added, and publicly known paperboard papermaking Paper is made by a machine. The basis weight of the paperboard base paper should be appropriately adjusted to the basis weight and is not limited.

  The coating apparatus for coating the surface treating agent in the present invention includes, for example, a two roll size press, a calendar size press, a blade metalling size press, a rod metalling size press, a gate roll size press, a gate roll coater, and a blade. A coating apparatus normally used in the field of coated paper, such as a coater, a rod coater, a bar coater, a rod blade coater, and an air knife coater, can be used as appropriate and is not limited.

  Examples of the polymer compound to be surface-treated in the present invention include natural polymer compounds such as sweet potato starch, potato starch, wheat starch, tapioca starch, and starch such as corn starch, carrageenan, laminaran, seaweed mannan, funari, Irish moss. , Agar, algae, alginate, etc. Plant mucilage such as gum, homopolysaccharide such as dextran, glucan, xanthan gum and levan, and microbial mucilage such as heterosaccharide such as succinoglucan, pullulan, curdlan and xanthan gum, glue, gelatin, casein Emissions, and proteins such as collagen and the like.

  Semi-natural products (semi-synthetic products) include viscose, methylcellulose, ethylcellulose, methylethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxypropylethylcellulose, carboxymethylhydroxy, as well as propylene glycol alginate. Examples thereof include fiber derivatives such as ethyl cellulose and hydroxypropyl methyl cellulose phthalate, modified gums, and modified starches. Examples of the modified gum include carboxymethyl guar gum, hydroxypropyl guar gum, and hydroxyethyl guar gum. Processed starch includes white dextrin, yellow dextrin, and baked starch such as bridish gum, enzyme-modified dextrins such as enzyme dextrin and shardinger dextrin, acid-degraded starch such as solubilized starch, and oxidized starch such as dialdehyde starch Pregelatinized starch such as modified and non-modified pregelatinized starch, starch starch phosphate, fatty acid starch, starch starch sulfate, starch nitrate, xanthate starch and starch starch such as carbamic acid starch Starch, sulfoalkyl starch, cyanoethyl starch, allyl starch, benzyl starch, carbamylethyl starch, etherified starch such as dialkylamino starch, methylol-crosslinked starch, hydroxyalkyl-crosslinked starch, phosphate-crosslinked starch, dicarboxylic acid-crosslinked starch, etc. Cross-linking Powder, starch polyacrylamide copolymer, starch polyacrylonitrile copolymer, cationic starch polyacrylate copolymer, cationic starch vinyl polymer copolymer, starch polystyrene / maleic acid copolymer, and starch polyethylene oxide copolymer And starch graft copolymers such as coalescence.

  Synthetic polymer compounds include polyvinyl alcohol, partially acetalized polyvinyl alcohol, allyl-modified polyvinyl alcohol, modified polyvinyl alcohols such as polyvinyl methyl ether, polyvinyl ethyl ether, and polyvinyl isobutyl ether, polyacrylates, and polyacrylate esters. , Polyacrylic acid derivatives and polymethacrylic acid derivatives such as polymethacrylate, polyacrylamide, polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, vinylpyrrolidone / vinyl acetate copolymer, carboxyvinyl polymer, styrene / maleic acid Examples thereof include a copolymer and a styrene / crotonic acid copolymer.

  Among these, the above-mentioned various starches or derivatives thereof and polyvinyl alcohol not only have excellent film-forming properties, but also do not reduce the adhesion of the laminate during lamination, and do not cause printing blisters when printing on the printed surface after lamination. Since it can prevent, it is used suitably in order to improve printing workability and to improve the processability and cosmetic properties of the final packaging material. Moreover, the mixture of these starches, or a mixed use with a synthetic polymer may be sufficient, and it is not limited.

  In addition to the polymer compound as the main component, the liquid surface-treated in the present invention may include a known and publicly available surface treatment agent such as a surface sizing agent, a surface paper strength agent, a dye, or a coloring dye as an auxiliary agent. It may be used in combination and is not limited.

In the present invention, the coating amount of the liquid to be surface treated is 0.25 to 1.0 g / m ² per side, preferably 0.3 to 0.9 g / m ² per side. If the coating amount is less than 0.25 g / m ² per side, the laminating adhesiveness at the time of laminating is good, but printing blisters are likely to occur at the time of printing after laminating. In addition, if the coating amount exceeds 1.0 g / m ² per side, the adhesion of the laminate at the time of laminating decreases, resulting in poor laminating adhesion, and the printing blistering at the time of printing after laminating also decreases. Processed product rate is significantly reduced and uneconomical.

  In the present invention, it is needless to say that the surface treatment may be performed on one or both sides as required, and the lamination may be performed on one or both sides if necessary. In addition, the paperboard for laminating of the present invention includes a paperboard before the surface treatment according to the present invention, a paperboard before laminating after the surface treatment, and further laminated on one or both sides of the paperboard for laminating. Although it can be printed on the laminate surface, it is preferable to print on the laminate surface after lamination from the viewpoint of cosmetics.

  Examples of the resin laminated on the paperboard for laminating processing of the present invention include those mainly composed of a polyethylene resin, a polypropylene resin, a polyester resin, a polycarbonate resin, or a mixture thereof, particularly melt extrusion coating properties. From the viewpoint of film-forming properties, those mainly composed of a polyethylene resin, a polypropylene resin or a mixture thereof are preferred.

Examples of polyethylene resins preferably used in the present invention include low density polyethylene resins, high density polyethylene resins, linear low density polyethylene resins, copolymers of ethylene with α-olefins such as propylene and butylene, ethylene Is a copolymer of acrylic acid, methacrylic acid, acrylic acid methyl ester, methacrylic acid methyl ester, etc., and a mixture thereof, and has various densities and melt flow rates (hereinafter referred to as JIS K 6760 melt flow). Although the rate is simply abbreviated as MI), those having a molecular weight and molecular weight distribution can be used, but usually a density of 0.90 to 0.97 g / cm ³ , an MI of 0.1 to 50 g / 10 minutes, preferably a density of 0.90 to 0 .94 g / cm ³ , MI 0.3 to 35 g / 10 min, molecular weight in the range of 20,000 to 250,000 alone Alternatively, two or more kinds can be mixed and used.

The polypropylene resin preferably used in the present invention is a polypropylene resin, a random polypropylene resin, a random polypropylene resin obtained by copolymerizing 1 to 10 mol% of an ethylene component with propylene as a main component, and a mixture thereof. Density, melt flow rate (hereinafter, melt flow rate defined in JIS K 6758 is simply abbreviated as MFR), molecular weight, and molecular weight distribution can be used. Usually, a density of 0.88 to 0.91 g / cm ³ , Those having a MFR of 10 to 45 g / 10 min, preferably MFR of 15 to 25 g / 10 min can be used alone or in admixture of two or more. Moreover, the compound resin which has a polyethylene-type resin and a polypropylene resin as a main component is preferable in order to improve the extrusion coating property of a polypropylene-type resin. As the compound resin, those having a mass ratio of polyethylene resin: polypropylene resin in the range of 1:99 to 35:65 are particularly preferable.

Examples of the polyester resin used in the present invention include polyethylene terephthalate resin, polybutylene terephthalate resin, polyester biodegradable resin, and mixtures thereof, and those having various densities and melt flow rates can be used. Specific examples include polyester resin (trade name: AP-270L, density 0.91 g / cm ³ , melt flow rate = 4 g / 10 min) manufactured by Mitsubishi Chemical Corporation. Moreover, as a polycarbonate-type resin used for this invention, the thing of various grades can be used, However, As a concrete representative example, the polycarbonate resin (brand name: NOVAREX 7022A, low-viscosity type) by Mitsubishi Chemical Corporation is used. Can be mentioned.

  When two or more different grades or types of resins used in the laminate according to the present invention are used in combination, specifically, for example, a combination of two or more polyethylene resins having different densities and melt flow rates, a polyethylene resin and In the case of combined use of polypropylene resin, combined use of polyethylene resin and polyethylene terephthalate resin, etc., those resins are preferably used as a resin composition comprising a compound resin prepared by melting and mixing in advance. As a method for preparing a compound resin by previously melting and mixing two or more different grades or types of resins, a simple melt mixing method, a multistage melt mixing method, or the like can be used. For example, using a extruder, a twin screw extruder, a heated roll kneader, a Banbury mixer, a pressure kneader, etc., a predetermined amount of a resin to be used in combination, and optionally various additives such as an antioxidant and a lubricant. In addition, the method of pelletizing the mixture after melting and mixing is advantageously used. When the resin to be used in combination is not directly used as a compound resin but is directly added to the melt extruder in the state of simple mixing and melt extrusion coating is applied, the adhesion between the base paper and the resin layer, the mutual mixing of the resin, molding Problems often occur in terms of workability.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. Further, “parts” and “%” shown in the examples represent parts by mass and mass% unless otherwise specified.

A pulp slurry containing the following pulp and internal chemicals was prepared, and a base paper having a basis weight of 320 g / m ² was made into a base material. The paper machine used was a long-mesh paper machine with a surface layer, a five-layer paper machine with a core layer, and a two-layer paper machine with a back layer, and was made at a speed of 150 m / min. In addition, 0.8 g / m < ² > of each acetylated potato starch was sprayed between each layer by spraying.

<Surface>
LBKP (freeness 450 mlcsf) 80 parts NBKP (freeness 470 mlcsf) 20 parts Commercial talc 10 parts Commercial rosin sizing agent 0.05 parts Commercial sulfuric acid band 0.4 parts Basis weight 45 g / m ²

<Core layer>
LBKP (freeness 430 mlcsf) 100 parts commercial rosin sizing agent 0.05 parts commercial sulfuric acid band 0.4 parts basis weight 230 g / m ²

<Back layer>
LBKP (freeness 450 mlcsf) 80 parts NBKP (freeness 470 mlcsf) 20 parts Commercial rosin sizing agent 0.05 parts Commercial sulfuric acid band 0.8 parts Basis weight 45 g / m ²

Subsequently, a surface treatment liquid having the following composition was applied to the base material made as described above with a liquid concentration of 5% and a B-type viscosity of 60 mPa · s, and 1.00 g / m of dryness per side with a two-roll size press. ² (both sides: 2.00 g / m ² ) was coated, dried and calendered to obtain a board for laminating.

<Size Press> Surface Treatment Liquid Oxidized Starch (manufactured by Nippon Food Processing Co., Ltd .; MS-3800) 10.0 parts Commercial Olefin Surface Sizing Agent 0.02 parts

Furthermore, the laminate board obtained as described above was laminated with low density polyethylene having a thickness of 22 μm at a set temperature of 290 ° C. after corona discharge treatment (56 W · min / m ² ) by an extrusion laminating method. The laminated paperboard of Example 1 was obtained.

The same procedure as in Example 1 was performed except that the viscosity of the surface treatment solution prepared in Example 1 was 40 mPa · s, and coating was absolutely dry 0.80 g / m ² (both sides 1.60 g / m ² ) per side. The laminated paperboard of Example 2 was prepared.

The laminated paperboard of Example 3 was prepared in the same manner as in Example 1 except that the surface treatment solution prepared in Example 1 was coated with 0.25 g / m ² (double-sided 0.50 g / m ² ) per side. Produced.

The oxidized starch in the surface treatment solution prepared in Example 1 was changed to polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; PVA-117, hereinafter referred to as PVA) and 0.95 g / m ² (both sides 1.90 g / m ² ) per side. ² ) A laminated paperboard of Example 4 was produced in the same manner as Example 1 except that it was coated.

(Comparative Example 1)
Comparative Example as in Example 1 except that the surface treatment liquid prepared in Example 1 was made to have a viscosity of 100 mPa · s and coated with absolutely dry 2.25 g / m ² (both sides 4.50 g / m ² ) per side. 1 laminated paperboard was produced.

(Comparative Example 2)
The surface treatment solution prepared in Example 1, per side bone dry 1.60 g / m ² (two-sided 3.20 g / m ²⁾ coated except that the the, the laminated paperboard of Comparative Example 2 in the same manner as in Example 1 Was made.

(Comparative Example 3)
Laminated paperboard of Comparative Example 3 in the same manner as in Example 1 except that the surface treatment solution prepared in Example 1 was coated with 0.15 g / m ² (double-sided 0.30 g / m ² ) per surface. Was made.

(Comparative Example 4)
Laminated paperboard of Comparative Example 4 in the same manner as in Example 1 except that 0 parts of oxidized starch was used in the surface treatment liquid used in Example 1 and a surface treatment liquid consisting only of a commercially available olefin type surface sizing agent was applied. Was made.

(Comparative Example 5)
Laminated paperboard of Comparative Example 5 in the same manner as in Example 4 except that the surface treatment solution prepared in Example 4 was coated with 0.18 g / m ² (double-sided 0.36 g / m ² ) per surface. Was made.

  The board for laminating produced in Examples 1 to 4 and Comparative Examples 1 to 5 was evaluated by the following evaluation method, and the results are shown in Table 1.

(Laminate adhesion)
After laminating on the paperboard for laminating, it was torn by hand, and the laminate film was further peeled off to observe the behavior of the laminate film, and sensory evaluation was performed. ○ indicates that the laminate film at the tearing portion has little stringing or no interfacial peeling, and is difficult to peel off, resulting in the destruction of the paperboard substrate. Δ indicates that the laminate film at the tearing part has a lot of stringing and elongation or peeling at the interface, and if it is carefully peeled off, it can be partially peeled off without breaking the paperboard substrate. X indicates a state in which the laminate film of the peeled portion is well stretched or peeled off at the interface, and can be peeled off relatively easily without breaking the paperboard substrate. ○ △ or Δ × indicates an intermediate state of each of ○, Δ, and ×. In the state of Δ to ×, there is a risk that the laminate film may be peeled off during use of the laminate paperboard as a packaging material. The result must be ○ or ○ △.

(IGT Fukule)
The IGT swelling after laminating was measured and evaluated according to JIS-P-8129. However, the IGT printer used a pendulum type. When the IGT swelling is 260 cm / s or less, there is a high risk of occurrence of surface peeling in the actual offset printing, particularly in the solid printing portion, and it is necessary that it is preferably 280 cm / s or more.

Rating:
From Table 1, Comparative Examples 1 and ² having a coating amount of 1.60 g / m ² or more on one side are inferior in both laminating adhesiveness and IGT swelling after laminating. Furthermore, it can be seen that Comparative Examples 3 to 5 having a coating amount of 0.18 g / m ² or less per side are inferior in laminating IGT swelling even though the laminating adhesiveness is very good.

On the other hand, Examples 1-4 which are in the range of the coating amount of 0.25-1.00 g / m < ² > per single side | surface of a high molecular compound have favorable lamination adhesiveness, and are IGT swelling after lamination. Also proved to be a good result.

  INDUSTRIAL APPLICATION Since this invention is excellent in lamination adhesiveness and the printing blistering characteristic at the time of printing, it can be utilized for the paperboard for lamination processing which improved the operativity of lamination processing, printing, and a shaping | molding process.

Claims (3)

A paperboard for laminating, characterized in that a liquid containing a polymer compound as a main component is provided with an absolute dry coating amount of 0.25 to 1.0 g / m ² per side on one or both sides of the paperboard by surface treatment.   The paperboard for lamination processing according to claim 1, wherein the polymer compound is at least one of starch or a derivative thereof and polyvinyl alcohol.   A method for processing a board for laminating, comprising: laminating on one or both sides of the board for laminating according to claim 1 or 2 and printing on the laminating surface.