JP2012108300A - Label and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a label having high film strength and a manufacturing method of the label.SOLUTION: A label is formed by depositing toner for labels, which contains a polylactic acid having a weight average molecular weight of 100,000 or more, as a binder resin on a medium for labels. A manufacturing method of the label comprises the steps of: forming a toner layer for labels, which contains a polylactic acid having a weight average molecular weight of 100,000 or more, as a binder resin on a medium for labels; and heat-fixing the toner layer for labels.

Description

  The present invention relates to a label and a manufacturing method thereof, and more particularly, to a label using an electrophotographic method and a manufacturing method thereof.

  2. Description of the Related Art Conventionally, a label producing method is known in which a pattern is printed on a label affixed to a release sheet, and the label is cut into an arbitrary shape with a blade shape (see, for example, Patent Documents 1 and 2). However, in this method, in order to create one type of label, it is necessary to create a printing plate and a blade shape. This method is effective when producing a large number of labels, but if the number of labels to be produced is small, the production cost of the plate and blade mold is high, resulting in an increase in the unit price of the label. There is a problem that it ends up.

  Therefore, the present applicant has previously proposed a method of producing a label by developing the toner into an arbitrary shape by an electrophotographic method and then performing a heat treatment (see, for example, Patent Document 3). According to this method, polyester resins and styrene acrylic resins that are widely used as toner resins are brittle resins, so they could not be used due to their poor film properties for use as label substrates. By using it, a certain degree of film strength could be imparted and it could be used as a label.

  On the other hand, the present inventors tried to use a polylactic acid resin that is biodegradable as a label base material and can reduce the environmental load because the raw material is not petroleum but a natural material. Conventionally, a label using polylactic acid is already known, but it is produced by an existing printing / die cutting method (for example, see Patent Document 4).

JP 09-168998 A Japanese Patent Laid-Open No. 11-033999 JP 2007-283745 A JP 09-314495 A

  This invention is made | formed in view of the above situations, and it aims at providing the label with a high film strength, and its manufacturing method.

  In order to solve the above problems, a first aspect of the present invention is characterized in that a label toner containing polylactic acid having a weight average molecular weight of 100,000 or more as a binder resin is applied to a label medium. Provide a label with

  In the label as described above, the label toner containing the polylactic acid can be applied to the label medium by an electrophotographic method.

  As said polylactic acid, what has a weight average molecular weight of 150,000 or more can be used. In addition, cross-linked polylactic acid can be used as the polylactic acid. In this case, castor oil can be used as a crosslinking agent.

  According to a second aspect of the present invention, a step of forming a label toner layer containing polylactic acid having a weight average molecular weight of 100,000 or more as a binder resin on a label medium, and heat-fixing the label toner layer Provided is a method for producing a label comprising the steps.

  In this case, the label toner layer can be formed on the label medium by an electrophotographic method.

  ADVANTAGE OF THE INVENTION According to this invention, the label which can form the toner film for labels with high film strength, and its manufacturing method are provided.

It is a figure which shows the label preparation process which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described.

  A label manufacturing process according to an embodiment of the present invention will be described with reference to FIG.

  First, a development medium 1 as shown in FIG. The development medium 1 has a configuration in which, for example, an adhesive layer 3 is formed on a release paper 2 and a coat layer 4 is formed thereon. The development medium 1 is sequentially developed with color toners by electrophotography, and a color toner image 5 is formed as shown in FIG.

  In this case, magenta toner, cyan toner, yellow toner, and black toner that are generally used in a color printer can be used as the color toner.

  The development medium 1 on which the color toner image 5 is formed is then subjected to label toner development. In label toner development, as shown in FIG. 1C, a solid image 6 of label toner covering the color toner image 5 is formed. As the label toner, a binder resin containing polylactic acid having a weight average molecular weight of 100,000 or more was used.

  Thereafter, as shown in FIG. 1D, the color toner image 5 and the solid image 6 of the label toner are thermally fixed, and a label toner film 7 is formed.

  The development medium 1 on which the label toner film 7 is formed as described above is cooled to room temperature and then used by the user. That is, the label 8 in which the color toner image 5 and the label toner film 7 are formed on the coat layer 4 and the pressure-sensitive adhesive layer 3 is formed on the back surface of the coat layer 4 is, as shown in FIG. It can peel from the release paper 2 by work.

  Since the label toner film 7 is formed of a toner containing polylactic acid having a weight average molecular weight of 100,000 or more as a binder resin, the film strength is high, and due to a hardness difference and a strength difference from the surrounding portions. It becomes possible to easily peel off the release paper 2. Moreover, it has sufficient strength as a label. Further, since the label toner film 7 is formed by an electrophotographic method, a label having an arbitrary shape can be easily manufactured with high accuracy.

  In the label manufacturing process described above, the color toner image 5 is formed on the coat layer 4 and then the label toner solid image 6 is formed. However, after the label toner solid image 6 is formed, the color toner image 5 It is also possible to form In any order, a label toner film having high film strength can be obtained.

  As described above, the color image and the label toner film are formed by using the electrophotographic process, but it is also possible to use the solid ink process.

  The polylactic acid used as the main component of the label toner has a weight average molecular weight of 100,000 or more. Further, it is preferable to use a polylactic acid having a weight average molecular weight of 150,000 or more because a particularly strong label can be obtained. If polylactic acid having a weight average molecular weight of less than 100,000 is used, it is difficult to obtain sufficient label strength.

  In addition, the polylactic acid is particularly preferably one obtained by crosslinking using a crosslinking agent during polymerization and further increasing the average molecular weight. By crosslinking polylactic acid, the molecular weight can be increased without extremely increasing the softening point, so that the label strength can be increased. As the cross-linking agent, ethylene glycol or castor oil can be used, and castor oil is particularly preferable.

  According to the knowledge of the present inventors, the toner obtained by the most widely used pulverization method is not necessarily suitable as the label toner. The toner produced by the pulverization method requires that the kneaded material containing the resin as a main component is easily broken. However, if the easily breakable resin is used for the toner for the label, the created label is also easily broken and gives sufficient strength as a label. You may not be able to. Therefore, it is preferable to use a toner manufactured by a method different from the pulverization method.

  As such a production method, there are a spray drying method, a dissolution suspension method, and a water-soluble resin kneading method. The spray drying method is a method of obtaining toner particles by spray drying a solution obtained by dissolving a toner component in a solvent, and is described in, for example, JP-A-2009-175632. The dissolution suspension method is a method in which a toner particle is formed by dispersing and precipitating a solution obtained by dissolving a resin in a solvent in water. There is an advantage that can be. The dissolution suspension method is described in, for example, Japanese Patent No. 3543554 and Japanese Patent Application Laid-Open No. 2009-230064. The water-soluble resin kneading method is a method for producing a toner by dispersing and kneading a toner material in a water-soluble resin and then washing the water-soluble resin with water, and is described in, for example, JP-A-2006-126359. ing.

  Examples of the present invention and comparative examples will be shown below to describe the present invention more specifically.

  The measuring method of the physical property value used in each example is shown below.

(Measurement of softening point)
The measurement is performed using a flow tester (CFT-500D: manufactured by Shimadzu Corporation). 1 g of a sample is taken, and the temperature at which half of the sample flows out from a nozzle having a diameter of 1 mm and a length of 1 mm under the conditions of a heating rate of 6 ° C./min and a load of 20 kg is defined as a softening point (1/2 method).

(Measurement of toner particle size)
Equipment: Multisizer II (manufactured by Coulter, Inc.)
Sample: A small amount of sample, purified water, and a surfactant were placed in a beaker and dispersed with an ultrasonic cleaner.

  Measurement: The aperture was 100 μm, the count was 50,000, and the volume average particle size was obtained. In this case, in the cumulative curve of the number particle size distribution, the particle size D50 corresponding to 50% of the total amount was taken as the average particle size.

(Measurement of molecular weight)
The weight average molecular weight (Mw) is a molecular weight measured by GPC (gel permeation chromatography) using a calibration curve prepared by a polystyrene sample having a known molecular weight as a standard. As a measuring device, GPC (manufactured by Shimadzu Corporation) and detector Rl are used.

(Synthesis of polylactic acid)
Synthesis example 1
100 parts by mass of L-lactide (manufactured by Purelac Japan Co., Ltd.) and 0.1 part by mass of stearyl alcohol were stirred at 190 ° C. in a nitrogen atmosphere. 0.05 parts by mass of tin octylate was added to the obtained mixture, and the mixture was further stirred at 190 ° C. for 2 hours. Thereafter, in order to remove the remaining L-lactide, stirring was continued for 1 hour under a reduced pressure of 10 mmHg.

  As a result, polylactic acid (PLA) having a weight average molecular weight (Mw) of 272,000 was obtained.

Synthesis example 2
Polylactic acid was polymerized in the same manner as in Synthesis Example 1 except that the amount of stearyl alcohol added was 0.15 parts by mass to obtain polylactic acid (PLA) having a weight average molecular weight (Mw) of 194,000. .

Synthesis example 3
Except that the addition amount of stearyl alcohol was 0.25 parts by mass, polylactic acid was polymerized in the same manner as in Synthesis Example 1 to obtain polylactic acid (PLA) having a weight average molecular weight (Mw) of 115,000. .

Synthesis example 4
Polylactic acid was polymerized in the same manner as in Synthesis Example 1 except that the amount of stearyl alcohol added was 0.40 parts by mass to obtain polylactic acid (PLA) having a weight average molecular weight (Mw) of 52,000. .

Synthesis example 5
Except that the addition amount of stearyl alcohol was 0.60 parts by mass, polylactic acid was polymerized in the same manner as in Synthesis Example 1 to obtain polylactic acid (PLA) having a weight average molecular weight (Mw) of 26,000. .

Synthesis Example 6
Polylactic acid was polymerized in the same manner as in Synthesis Example 1 except that 0.40 parts by mass of ethylene glycol was added as a crosslinking agent during the polylactic acid polymerization to obtain crosslinked polylactic acid (PLA). In addition, since the obtained polylactic acid was insoluble in a solvent, the molecular weight could not be measured by GPC, but its weight average molecular weight (Mw) exceeded 150,000.

Synthesis example 7
Polylactic acid was polymerized in the same manner as in Synthesis Example 1 except that 0.40 parts by mass of castor oil was added as a crosslinking agent during the polylactic acid polymerization, to obtain crosslinked polylactic acid (PLA). In addition, since the obtained polylactic acid was insoluble in a solvent, the molecular weight could not be measured by GPC, but its weight average molecular weight (Mw) exceeded 150,000.

<Manufacture of toner>
Toner production example 1
In this production example, toner is produced by a spray drying method.

  The polylactic acid resin obtained in Synthesis Example 1 was dissolved in tetrahydrofuran (THF) to prepare a 13 g / L solution.

  The obtained polylactic acid THF solution was sprayed under the following conditions with a closed spray drying apparatus (TR16; manufactured by Pris Co., Ltd.) under a nitrogen gas atmosphere.

Solution supply rate: 4 kg / h
Outlet temperature: 60 ° C
As a result, polylactic acid particles having an average particle diameter of D50 (volume) 10.8 μm were obtained.

  In order to further remove THF remaining in the particles, the particles were dried at room temperature for 12 hours under a reduced pressure of 30 nmHg. To 100 parts by mass of the dried polylactic acid particles, 0.5 parts by mass of hydrophobized silica particles TG810G (manufactured by Cabot Corp.) and 3 parts by mass of RY50 (manufactured by Nippon Aerosil Co., Ltd.) are stirred with a Henschel mixer. Were added externally to obtain a polylactic acid toner.

Toner production examples 2 to 5
In the same manner as in Toner Production Example 1, four types of polylactic acid toners were obtained using the polylactic acid obtained in Synthesis Examples 2 to 5.

Toner Production Example 6
In this production example, a toner is produced by a dissolution suspension method.

  100 parts by mass of the polylactic acid obtained in Synthesis Example 1 was dissolved in 400 parts by mass of chloroform, and the resulting solution was added to a 0.5% polyoxyethylene alkyl ether aqueous solution at 80 ° C. and emulsified with a high-pressure emulsifier. did.

  Chloroform was distilled off from the emulsion under reduced pressure to obtain a polylactic acid suspension. The polylactic acid suspension was separated by filtration, ion-exchanged water was added again, and the polylactic acid particles were washed seven times by the same operation.

  After the obtained polylactic acid particles were dried, silica was externally added in the same manner as in Toner Production Example 1 to obtain a polylactic acid toner.

Toner production example 7
In this production example, a toner is produced by a water-soluble resin kneading method.

  The polylactic acid obtained in Synthesis Example 1 was mixed with a polyethylene glycol resin and kneaded with a biaxial extrusion kneader. The kneaded product discharged from the kneader was immersed in water as it was to dissolve polyethylene glycol in water. Thereafter, the precipitated polylactic acid particles were collected and dispersed again in ion exchange water. The same washing operation was repeated 7 times.

  Coarse particles were removed from the washed polylactic acid particles through a mesh having a mesh size of 32 μm. Thereafter, it was dried and silica was externally added in the same manner as in Toner Production Example 1 to obtain a polylactic acid toner.

Toner production example 8
A polylactic acid toner was obtained in the same manner as in Toner Production Example 7 except that the polylactic acid obtained in Synthesis Example 6 was used.

Toner Production Example 9
A polylactic acid toner was obtained in the same manner as in Toner Production Example 7 except that the polylactic acid obtained in Synthesis Example 7 was used.

<Creation of label mount>
Spray adhesive 55 (manufactured by 3M Co., Ltd.) was applied as an adhesive to release paper (SHA70; manufactured by Sanei Kaken Co., Ltd.). After drying the volatiles contained in the adhesive, melt and knead the polyester resin for the Kao toner (softening point 120 ° C) and titanium oxide (CR-50; manufactured by Ishihara Sangyo Co., Ltd.) on the surface of the adhesive layer. After the applied particles (D50 (volume) 8 μm) were applied, the powder was melted at 160 ° C. and coated.

<Create label>
Example 1
Using the electrophotographic process, a color toner image and a solid image of the label toner are sequentially formed on the A4 size label mount using the color toner and the label toner produced in the toner production example 1 as a label base material. Then, the color mount and the label toner were fixed by heat-pressing at 200 ° C. the label mount on which the toner was developed.

  After cooling to room temperature, the polylactic acid film on the mount was peeled off to obtain a polylactic acid label having a thickness of 90 μm on which an image was drawn. Further, a 50 μm polylactic acid label was also prepared by adjusting the development amount of the toner to be the label substrate.

  As the color toner, N5 printer toner manufactured by Casio Computer Co., Ltd. was used. Further, as the developing machine, a developing device based on an N5 printer was used.

Examples 2-7
The thickness is 90 ± 5 μm and 50 ± 5 μm in the same manner as in Example 1 except that the polylactic acid toner obtained in Toner Production Examples 2, 3, 6-9 was used as the label toner. Got a label.

Comparative Examples 1 and 2
Labels having thicknesses of 90 ± 5 μm and 50 ± 5 μm were obtained in the same manner as in Example 1 except that the polylactic acid toner obtained in Toner Production Examples 4 and 5 was used as the label toner. .

<Evaluation of label>
The label strength was determined according to the following criteria from the tensile strength and tear strength of the obtained label.

  (Double-circle): It has the outstanding label intensity | strength exceeding the grade which can function as a label.

  ○: It has a label strength that can function as a label.

  (Triangle | delta): It has label intensity a little lower than the grade which can function as a label.

  X: The label strength is considerably lower than the level capable of functioning as a label.

Table 1 below shows the evaluation results of the grindability of the labels obtained in Examples 1 to 7 and Comparative Examples 1 and 2 and the film properties of the toner film.

  From Table 1 above, since the labels obtained in Examples 1 to 7 each used polylactic acid having a weight average molecular weight of 100,000 or more as the label toner, the strength of the labels was almost good. In particular, the strength of the labels according to Examples 1, 2, 4 to 7 using polylactic acid having a weight average molecular weight of 150,000 or more was excellent. Regarding Example 3, the label strength was slightly inferior in the case of a thin label of 50 μm.

  On the other hand, since the labels obtained from Comparative Examples 1 and 2 both used polylactic acid having a weight average molecular weight of less than 100,000 as the label toner, the label strength was low.

  From the above results, the strength of the label mainly composed of polylactic acid depends on the molecular weight of polylactic acid irrespective of the toner production method, and the weight average molecular weight (Mw) is 100,000 or more. It can be seen that it is preferably 150,000 or more.

  DESCRIPTION OF SYMBOLS 1 ... Development medium, 2 ... Release paper, 3 ... Adhesive layer, 4 ... Coat layer, 5 ... Color toner image, 6 ... Solid image of label toner, 7 ... Label toner film, 8 ... Label.

Claims (7)

  A label obtained by adhering a label toner containing polylactic acid having a weight average molecular weight of 100,000 or more as a binder resin to a label medium.   2. The label according to claim 1, wherein the label toner containing polylactic acid is attached to a label medium by an electrophotographic method.   The label according to claim 1 or 2, wherein the polylactic acid has a weight average molecular weight of 150,000 or more.   The label according to any one of claims 1 to 3, wherein the polylactic acid is a crosslinked polylactic acid.   The label according to claim 4, wherein the polylactic acid is polylactic acid crosslinked using castor oil as a crosslinking agent.   A label comprising a step of forming a label toner layer containing polylactic acid having a weight average molecular weight of 100,000 or more as a binder resin on a label medium, and a step of thermally fixing the label toner layer. Manufacturing method.   6. The method for producing a label according to claim 5, wherein the label toner layer is formed on the label medium by an electrophotographic method.

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