JP3877072B2 - Paper processed products - Google Patents

Description

  The present invention relates to a processed paper product bonded through an adhesive layer made of a novel biodegradable resin composition.

Resin emulsions obtained by emulsion polymerization of vinyl acetate monomer (hereinafter abbreviated as VAc), acrylic monomers and the like have been widely used in adhesives, paints, paper processing, fiber processing, and the like. Although widely used in this way, there are various problems.
The problem is that the adhesive is not biodegradable, so if it is discarded after being used after being processed into paper, it will not decompose and cause environmental pollution. There is concern about environmental hormones in plasticizers such as dibutyl phthalate that are added to ensure film-forming properties, and the addition of such plasticizers gives flexibility to the film, resulting in low temperatures. Although film-forming properties can be obtained, the film strength is weakened and heat resistance is reduced.

JP 2002-97437 A JP 2001-262100 A

In view of such a situation, the above-mentioned problems are to be solved by developing a paper processed product bonded through an adhesive layer of a biodegradable resin composition.

The present invention relates to a processed paper article bonded through an adhesive layer made of a biodegradable resin composition, more specifically, a biodegradable adhesive made of a vinyl acetate resin emulsion containing a biodegradable resin. Therefore, paper that has properties such as adhesiveness and flexibility, and that remains bonded even when discarded in the natural environment through an adhesive layer that has biodegradability, does not cause problems such as environmental pollution. To provide processed products.

  The biodegradable resin composition according to the present invention is prepared by emulsion-polymerizing VAc in the presence of 1 biodegradable resin emulsion, and 2 by dissolving the biodegradable resin in VAc in the presence of an emulsifier. It is prepared by a method in which an emulsion emulsified by forcible emulsification is dropped into a reaction solution in which an emulsifier is dissolved in water and emulsion polymerization is performed.

The processed paper product of the present invention is used as a packaging material and the like because it is bonded to the bond between paper and paper, paper and other materials via an adhesive layer made of a biodegradable resin composition. Even if it is discarded as it is, biodegradation also proceeds in the adhesive layer together with paper etc., and it will be in a decomposed state that does not retain the original shape, so environmental pollution can be avoided.
In addition, since the biodegradable resin composition according to the present invention does not contain a plasticizer such as dibutyl phthalate, which may cause endocrine disrupting action, it can be used safely in various paper processing fields without fear of environmental pollution. .

Examples of the method 1 include polyethylene succinate, polyethylene succinate adipate, polybutylene succinate, polybutylene succinate adipate, polycaprolactone, and polycaprolactone butylene succinate. Biodegradable resin emulsion prepared from degradable resin, or biodegradable prepared from modified polylactic acid, modified polyhydroxybutyrate, modified esterified starch, etc. modified so that the glass transition point is 0 ° C. or lower There is a method of emulsion polymerization of VAc by a known method in the presence of a conductive resin emulsion.
Such a biodegradable resin emulsion originally does not form a film at 0 ° C. because it is a crystalline polymer. However, by emulsion polymerization of VAc using these as seeds, the polymers are combined at the molecular level to prevent crystallization of the biodegradable resin, so that the low-temperature film-forming property due to the glass transition point as described above is obtained. It is done.

In the above method 1, water and polyvinyl alcohol (hereinafter abbreviated as PVA) as an emulsifier are mixed and dissolved in a polymerization reaction vessel, a biodegradable resin emulsion is added, and VAc is added using a polymerization initiator. Can proceed. In this case, part or all of VAc is added to the polymerization vessel together with the polymerization initiator, water and the biodegradable resin emulsion, or part or all of VAc is added continuously or intermittently during the polymerization. You can proceed while.
Since the biodegradability of the biodegradable resin composition obtained by this synthesis method is determined by the ratio of the biodegradable resin emulsion to the whole, the biodegradability required during the synthesis, emulsion polymerization, and synthesis This can be determined in consideration of the stability and cost of the resin emulsion, low-temperature film-forming properties, and the like.
The degree of biodegradation is specified in JISK6950, and generally 60% or more, which is a standard for easy degradability, is required.
In order to ensure low-temperature film-forming properties together with such biodegradability, the solid content of the biodegradable resin emulsion is required to be 10 parts by weight or more with respect to 100 weight of the solid content of the entire resin emulsion. If it is 10 parts by weight or less, sufficient biodegradability and expected low-temperature film-forming properties cannot be obtained.

As the second method, a biodegradable resin such as polycaprolactone (hereinafter abbreviated as PCL) dissolved in VAc is added to an aqueous solution in which an emulsifier is dissolved to prepare an emulsion. There is a method in which the emulsion is added dropwise while stirring in an aqueous solution in which an emulsifier is dissolved in water, and the emulsion polymerization is advanced to prepare.
Since the biodegradability of the biodegradable resin composition obtained by this synthesis method is determined by the ratio of the biodegradable resin in the entire composition, the solubility of the biodegradable resin in VAc, the required biodegradability, and emulsification It can be determined in consideration of the stability of polymerization and the synthesized resin emulsion, cost, and low-temperature film-forming properties.
The degree of biodegradation is defined in JISK6950 as described above, and generally 60% or more, which is a standard for easy degradability, is required.
The blending ratio of the biodegradable resin is preferably 15 parts by weight or more with respect to 100 parts by weight of the total of VAc and biodegradable resin from the viewpoint of biodegradability. A blending ratio below this is not suitable because the biodegradability is not sufficient.

In the above method 2, when PCL is selected as the biodegradable resin, it itself has a glass transition point of −60 ° C., but it has a crystallinity and thus has a melting point of 60 ° C. No film formation can be expected. However, when emulsion polymerization is performed with PCL dissolved in VAc, both resins are complexed at the molecular level and the crystallinity of PCL is lost. Flexibility is imparted to the vinyl resin, and low-temperature film-forming properties can be obtained without the use of a plasticizer.
Although low-temperature film-forming property is obtained by such an action, the blending ratio of the biodegradable resin VAc and the biodegradable resin with respect to 100 weights in total is 15 as well as biodegradability from the viewpoint of low-temperature film-forming property. Part by weight or more is preferable.

As the polymerization initiator used in the methods 1 and 2, a peroxide-based initiator, an azo-based initiator, a persulfate-based initiator, or the like is used.
Examples of peroxide initiators include benzoyl peroxide, lauryl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, butyl hydroperoxide, and hydrogen peroxide.
Examples of the azo initiator include azobisisobutylnitrile, azobiscyanovaleric acid, azobiscyanopentanoic acid, and the like.
Examples of persulfate initiators include ammonium persulfate, potassium persulfate, and sodium persulfate.

PVA used as an emulsifier has a saponification degree of 86 to 90% and a polymerization degree of 400 to 4000, which has excellent balance of polymerization stability, standing stability, low temperature film-forming property, structural viscosity, water resistance, etc. Used together.
As the emulsifier, a surfactant, an aqueous polymer, etc. may be used in addition to PVA.

In addition to VAc, it can also be copolymerized with a comonomer such as (meth) acrylic acid ester, vinyl propionate, vinyl versatate, (meth) acrylic acid and the like.
If necessary, fillers, pigments, antifoaming agents, preservatives, etc. can be added as needed.

  The polymerization temperature varies depending on the type of polymerization initiator used. For example, when polymerization is advanced by thermal decomposition such as ammonium persulfate, a temperature of 60 ° C. or higher is suitable. Moreover, in the redox system which combined the peroxide and the reducing agent, it can proceed at 60 ° C. or lower.

The biodegradable resin composition according to the present invention can be used for applications in various fields such as paint and fiber processing in addition to an adhesive.
As a specific application example, a case where the biodegradable resin composition is used as an adhesive for paper processing will be described below. Examples of paper processing adhesives are used for bonding between papers and between paper and other materials. Examples of bonding between papers include packaging materials, packing materials, cushioning materials, paper tubes, and slip sheets. Can be mentioned. Examples of adhesion between paper and other materials include paper and cloth, non-woven fabric, resin film, and wood.

The biodegradable adhesive is applied to paper or other materials by application means such as a brush, a roll, or a spray. The coating amount is in the range of about 1 to 300 g / m ² depending on the thickness and material of paper and other materials.
In addition, the entire application and partial application are appropriately selected as the application form, and the application form according to the application, finish, and other requirements of paper products such as grid, line, dot, and spiral is selected as the partial application. Can be processed.

Hereinafter, synthesis examples of biodegradable resin compositions and processed paper products using the same will be described with reference to examples and comparative examples. The parts by weight are described simply as parts.
Preparation example of biodegradable resin composition 1 282 parts of water and 30.4 parts of PVA (average polymerization degree 500, saponification degree 88%) were added to a reaction vessel equipped with a stirrer, temperature controller, reflux condenser, and thermometer. In addition, after heating to 80 ° C and dissolving, polybutylene succinate adipate resin emulsion prepared with PVA as an emulsifier (Showa Polymer Co., Ltd. Bionole Emulsion EM-530, solid content 53%, viscosity at 23 ° C 85 parts of 3 pa · s glass transition temperature -55 ° C was added. While stirring while maintaining the temperature in the system at 80 ° C., an aqueous solution in which 1 part of 35% hydrogen peroxide solution was dissolved in 10 parts of water and 165 parts of VAc were added dropwise over 3 hours to proceed emulsion polymerization at 80 ° C. . The obtained biodegradable resin composition 1 had a solid content of 41.9%, a film forming temperature of 0 ° C., and a viscosity of 19 pa · s at 23 ° C.
The biodegradability of the biodegradable resin composition 1 after 45 days as defined in JISK6950 is as shown in Table 1.

Preparation Example of Biodegradable Resin Composition 2 To the same reaction vessel used for the preparation of biodegradable resin composition 1 , add 130 parts of water, 10 parts of PVA having an average polymerization degree of 500 and a saponification degree of 88 mol% as an emulsifier. , Polycaprolactone “Cell Green PH-5”, which is a biodegradable resin, heated to 80 ° C. and dissolved in PVA (number average molecular weight 6 measured by GPC method, manufactured by Daicel Chemical Industries, Ltd.) 40,000) 31.3 parts dissolved in 135 parts of VAc were added to 78 parts of the same 15% aqueous solution of PVA as above, and 60 parts of water was added to force stirring at 1000 RPM to give an emulsion. the emulsified liquid and 1 part of ammonium persulfate those dissolved in 10 parts of water, 80 ° C. is heated, stirred the dropwise over 3 hours in a dispersing medium recommend emulsion polymerization biodegradable tree The composition 2 was prepared. The viscosity at 23 ° C. was 17 pa · s, the film forming temperature was 0 ° C., and the solid content was 41.4%.
The biodegradability of the biodegradable resin composition 2 after 45 days as defined in JISK6950 is as shown in Table 1.

Preparation of vinyl acetate resin emulsion composition 3 Using the same reaction vessel used for the preparation of biodegradable resin composition 1, 256 parts of water, 17 parts of PVA having an average polymerization degree of 500 and a saponification degree of 88 mol% After the parts were heated to 80 ° C. and dissolved, 150 parts of VAc and 1 part of ammonium persulfate dissolved in 10 parts of water were added dropwise over 3 hours while stirring at the same temperature to proceed with emulsion polymerization. , 18 parts of dibutyl phthalate was added as the Chi plasticizer and completion of the dropwise addition, to prepare a vinyl acetate resin emulsion composition 3 was cooled. The viscosity at 23 ° C. was 14 pa · s, the film forming temperature was 2 ° C., and the solid content was 41.0%.
The degree of biodegradation defined in JISK6950 of the vinyl acetate resin emulsion composition 3 was as shown in Table 1.

Example, after the comparative example basis weight 50 g / ^{m 2} kraft paper to biodegradable resin compositions 1, 2 and acetic acid vinyl resin emulsion 3 was 50 g / ^{m 2} coating, basis weight 30 g / ^{m 2} kraft paper After being laminated and pressure-bonded, they were dried to process the slip sheets of Examples 1 and 2 and Comparative Example 1 .
After burying the interleaving papers of Examples 1 and 2 and Comparative Example 1 for 3 months in the green ground of Aika Kogyo Co., Ltd., Kajimeji Factory for 3 months, the peel strength was measured for those dug out. As shown, in Examples 1 and 2, the adhesive layer was biodegraded and the adhesive strength was lost, so the adhesive layer was peeled off. In Comparative Example 1, the adhesive layer was hardly biodegraded, so the peel strength was Was recognized

Measurement method In the biodegradation measurement method specified in JISK6950, the biodegradation after 45 days is measured.

The processed paper products according to the present invention are used as various paper processed products, and are discarded and expected to be biodegradable, such as packaging materials, packaging materials, food and drink containers, labels, etc. In the future, the use is expected to expand.

Claims (2)

A water-based biodegradable resin emulsion composition prepared by emulsion polymerization of vinyl acetate monomer in the presence of a biodegradable resin emulsion and having a minimum film forming temperature of 0 ° C. or less is applied and bonded by pressing. Paper processed product characterized by being biodegradable. An emulsion prepared by forcibly emulsifying a biodegradable resin dissolved in a vinyl acetate monomer in the presence of an emulsifier and dropping it into a reaction solution in which the emulsifier is dissolved in water. A paper processed product characterized in that it is bonded by applying a water-based biodegradable resin emulsion composition having a membrane temperature of 0 ° C. or less and pressing, and has biodegradability.