JP2002339293A - Resin composition for water-proof paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for moisture-proof paper having excellent moisture-proof and water-proof properties and water dissolution in the recovery of used paper, particularly having antiblocking properties. SOLUTION: 0.001-0.2 pt.wt., per 100 pts.wt. of ethylenically unsaturated monomer is used and the monomer is emulsion-polymerized with the redox reaction using an reducing agent and an emulsifier, as the oxygen concentration in the reaction aqueous phase is kept in 0 ppm according to JIS K0102 to produce ultrahigh molecular weight emulsion having the glass transition point of -10-50 deg.C. The objective resin composition for water-proof paper is obtained by adding 1-7 pts.wt. of wax emulsion to 100 pts.wt. of the ultrahigh molecular weight emulsion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for imparting moisture-proof properties to paper, and more particularly to a resin composition which is applied to high-quality paper, kraft paper or the like to form a moisture-proof layer, thereby providing moisture-proof properties and recovering recovered paper. The present invention relates to a resin composition that provides a moisture-proof paper having excellent water disintegration properties, particularly excellent blocking resistance.

[0002]

2. Description of the Related Art As a means for imparting moisture proof and waterproof properties to wrapping paper, there is a method of laminating polyethylene, polypropylene, polyvinylidene chloride or the like onto base paper, which is effective because it is inexpensive and has excellent moisture proof properties. Although it can be said to be a means, since water disintegration at the time of recycling is inferior, a problem is likely to occur at the time of recovery of used paper. In order to solve this problem, there has been proposed a method in which a wax emulsion is blended with a synthetic rubber latex or an acrylamide emulsion and applied to a base paper (Japanese Patent Publication No. 55-22597, Japanese Patent Application Laid-Open No. 3-27-27).
No. 9492).

Further, when synthetic rubber latex or acrylic emulsion is designed to have a relatively low glass transition temperature in consideration of resin film-forming properties, the moisture-proof property of laminated paper can be exhibited, but moisture-proof paper is stacked. There is a possibility that blocking may occur at the time or in the packaged contents, or that the water disintegration at the time of collecting the used paper may be reduced. On the other hand, if the glass transition temperature is set relatively high, the blocking resistance and the water disintegration during recovery of used paper are improved, but the coated paper is folded because the moisture resistance is reduced due to poor film formation and the resin becomes brittle. Moisture resistance at the time is significantly reduced. Therefore, a method of increasing the glass transition temperature of the resin and increasing the blending of the wax-based emulsion in order to balance the moisture proofing property, the water disintegration property at the time of recovery of the used paper, and the blocking resistance (JP-A-6-287890).
Japanese Patent Application Laid-Open No. 8-1766992), a method of copolymerizing a small amount of a silane coupling agent (JP-A-10-226987), a method of blending a synthetic rubber latex, an acrylic emulsion and paraffin wax (JP-A-8-176992), A method of blending a self-crosslinkable synthetic resin emulsion obtained by copolymerizing an unsaturated monomer with a wax emulsion (Japanese Patent Laid-Open No. Hei 10-114851), and a method of blending a wax emulsion having an acrylic gel fraction within a certain range. Numerous methods have been proposed, such as a method of blending a core / shell type synthetic rubber latex and a wax-based emulsion (Japanese Patent Application Laid-Open No. 11-131386).

[0004]

As described above, various proposals have been made to impart moisture-proof and waterproof properties to wrapping paper, and to obtain moisture-proof paper having excellent water disintegration property and blocking resistance at the time of recovery of used paper. However, it is still insufficient to satisfy all of these performances. An object of the present invention is to provide a resin composition for moisture-proof paper which is excellent in moisture-proof and waterproof properties and water disintegration at the time of recovery of used paper, particularly excellent in blocking resistance.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a wax-based emulsion was added to an ultra-polymerized emulsion obtained by emulsion polymerization by a redox reaction under specific conditions. It has been found that by applying the compounded resin composition to paper, a moisture-proof paper having excellent moisture-proof and waterproof properties, water disintegration during recovery of used paper, and particularly excellent blocking resistance can be obtained, and the present invention has been achieved.

That is, the present invention relates to an ethylenically unsaturated monomer 1
0.001 to 0.2 parts by weight of a hydroperoxide and / or a persulfate is used per 100 parts by weight, and the oxygen concentration of the aqueous phase of the reaction system is determined to be 0 p by the measuring method according to JIS K0102.
pm, and 100 parts by weight of an ultra-high molecular weight emulsion having a glass transition temperature of −10 to 50 ° C. obtained by emulsion polymerization by a redox reaction using a reducing agent and an emulsifier. ~ 7
It is a moisture-proof paper resin composition in which parts by weight are blended.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The ethylenically unsaturated monomer which is the main component of the ultrahigh molecular weight emulsion in the resin composition for moisture-proof paper of the present invention has at least one polymerizable vinyl group, Preferred examples include styrene, methyl methacrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate, methacrylic acid, acrylic acid and the like, and other copolymerizable ethylenically unsaturated monomers can also be used in combination. Specifically, 1 to 18
(Meth) acrylates, aromatic vinyls, heterocyclic vinyls, vinyl esters, α, β- having a linear, branched or cyclic alkyl chain having two carbon atoms
Unsaturated mono- or dicarboxylic acids, carboxyl group-containing vinyls, vinyl cyanides, amide or substituted amide group-containing α, β-ethylenically unsaturated monomers, carbonyl group-containing α, β-ethylenically unsaturated units And α, β-ethylenically unsaturated monomers containing a sulfonic acid group.

In the present invention, the hydroperoxide used as a polymerization initiator in producing an ultrahigh molecular weight emulsion includes cumene hydroperoxide, t-butyl hydroperoxide, diisopropylbenzene hydroperoxide, p-methane hydroperoxide,
1,3,3-tetramethylbutyl hydroperoxide and the like. Examples of the persulfate include potassium persulfate and ammonium persulfate. The amount of the hydroperoxide and / or persulfate used as the redox initiator is based on the total amount of the ethylenically unsaturated monomers (total amount).
The amount is 0.001 to 0.2 part by weight, preferably 0.01 to 0.1 part by weight, based on 00 parts by weight. If the amount is less than 0.001 part by weight, not only the time is significantly required for polymerization but also a large amount of unreacted monomer remains. On the other hand, if the amount is more than 0.2 parts by weight, the degree of polymerization is reduced, and it does not lead to ultra-high molecular weight.

The type of reducing agent used in combination with the redox initiator hydroperoxide or persulfate is not particularly limited, but specific examples thereof include reducing organic compounds (ascorbic acid, tartaric acid, citric acid, glucose, formaldehyde). Sulfoxylate metal salts) and reducing inorganic compounds (sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium metabisulfite, etc.).
Although there is no upper limit of the amount of the reducing agent to be used, preferably, it is 0.001 to 100 parts by weight of all ethylenically unsaturated monomers.
0.2 parts by weight. If the amount is too small, the polymerization does not proceed smoothly. If the amount is too large, the performance (moisture-proof property, etc.) of the polymerization product is lowered, and a large amount of aggregates are generated during the polymerization.

[0010] Emulsifiers used for emulsion polymerization of ultrahigh molecular weight emulsions include anionic emulsifiers (sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, etc.) and nonionic emulsifiers (polyoxyethylene alkyl ether) generally used in emulsion polymerization. , Polyoxyethylene alkyl phenyl ethers, etc.), there is no problem in terms of polymerization, but a reactive emulsifier is preferred for the purpose of further improving the moisture resistance, which is an important performance item of the present invention. The reactive emulsifier is an anionic or nonionic emulsifier having a radically polymerizable unsaturated double bond in the molecule. Specific examples of the anionic reactive emulsifier include “Latemul S-180A”.
(Manufactured by Kao Corporation) "," Adecaria Soap SE-10 "
N (manufactured by Asahi Denka Kogyo Co., Ltd.) "," AQUARON HS-1
0 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) "," Antox MS
-60 (manufactured by Nippon Emulsifier Co., Ltd.) "," Eleminol J
S-2 (manufactured by Sanyo Chemical Industries, Ltd.) "and the like.
Specific examples of the nonionic reactive emulsifier include “AQUALON RN-20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)” and “Adecaria Soap NE-20 (manufactured by Asahi Denka Kogyo Co., Ltd.)”.

The amount of the emulsifier used in the emulsion polymerization of the ultra-high molecular weight emulsion depends on the amount of the raw material ethylenically unsaturated monomer 10
0.5 to 3 parts by weight per 0 parts by weight is preferred. 0.5
If the amount is less than parts by weight, there is a problem in stability during polymerization, and aggregates are easily generated. If the amount is more than 3 parts by weight, the moisture-proof property tends to be lowered.

In the present invention, as a means for producing a stable emulsion in a relatively short time even though the amount of the polymerization initiator used is extremely small, the oxygen concentration of the aqueous phase of the reaction system is adjusted to 5% by weight of aqueous sodium sulfite solution. It is indispensable to carry out the polymerization under the condition kept lower than the oxygen concentration. When the dissolved oxygen concentration exceeds this level, the amount of the polymerization initiator needs to be increased, and the molecular weight of the polymer decreases.

In the reaction, first, a predetermined amount of an ethylenically unsaturated monomer, an emulsifier, and water are charged into a reactor. On the other hand, the remaining ethylenically unsaturated monomer, emulsifier, and water are emulsified,
Charge the dropping funnel. Nitrogen gas is injected into both the reactor and the dropping funnel to perform deoxygenation. The dissolved oxygen in the aqueous phase of the reaction system is kept at 0 ppm by the measuring method according to JIS K0102. For example, the electrode is immersed in a 5% by weight aqueous solution of sodium sulfite and measured using a dissolved oxygen concentration meter (manufactured by Toa Denpa Kogyo Co., Ltd.) whose oxygen concentration is calibrated to 0 ppm. At this point, the emulsion polymerization is started. If the concentration of dissolved oxygen in the aqueous phase of the reaction system is high, radical termination reactions occur frequently and the polymerization rate is greatly reduced, so that the amount of unreacted monomers increases. Even if an emulsion is obtained, the molecular weight is small and the features of the product of the present invention cannot be obtained. The temperature of the redox reaction is 50 ° C. or lower, preferably 40 ° C. or lower.

The glass transition temperature of the ultrahigh molecular weight emulsion obtained by emulsion polymerization of an ethylenically unsaturated monomer is as follows:
10 to 50 ° C is preferable, and 10 to 30 ° C is more preferable. Emulsions obtained by ordinary emulsion polymerization have problems in blocking resistance at the above glass transition temperature, while ultrahigh molecular weight emulsions have good blocking resistance even at relatively low glass transition temperatures. -10 ° C
If the molecular weight is lower than this, the problem of blocking resistance tends to occur even when the molecular weight is increased, and if the temperature is higher than 50 ° C., the moisture-proof property is significantly reduced due to poor film formation. When a pH adjuster is required during the production of the ultrahigh molecular weight emulsion of the present invention, an alkali such as ammonia, sodium hydroxide or potassium hydroxide can be used.
Ammonia that evaporates during drying and does not remain is particularly preferable in terms of moisture resistance.

The wax emulsion used in the present invention includes an emulsion obtained by forcibly emulsifying paraffin wax, microcrystalline wax, fatty acid wax and the like, and a self-dispersible polyethylene wax emulsion. Above all, a wax emulsion obtained by forcibly emulsifying paraffin wax having a melting point of 40 to 90 ° C. is preferable.
The amount of the wax-based emulsion is 1 to 7 parts by weight, preferably 2 to 5 parts by weight, based on 100 parts by weight of the ultrahigh molecular weight emulsion obtained by emulsion polymerization of the ethylenically unsaturated monomer. is there. If the amount is less than 1 part by weight, a satisfactory moisture-proof property cannot be obtained, and if the amount is more than 7 parts by weight, the coated paper may be slippery when piled up, and the wax may be transferred to the package contents with time. . The resin composition for moisture-proof paper of the present invention comprising an ultrahigh molecular weight emulsion and a wax-based emulsion may further contain, if necessary, a thickener, an antifoaming agent, a pigment, a dispersant, a preservative, and the like. .

In the present invention, by keeping the dissolved oxygen concentration in the aqueous phase of the reaction system extremely low, a resin composition for moisture-proof paper having a molecular weight about 10 times that of the emulsion obtained by conventional emulsion polymerization can be obtained. Can be Since the resin composition for moisture-proof paper of the present invention has an ultra-high molecular weight, even at a relatively low glass transition temperature, it is excellent in moisture-proof property, water disintegration at the time of recovery of used paper, particularly excellent in blocking resistance, and It is effective as a moisture-proofing agent for paper and kraft paper.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited to these Examples. In the following Examples and Comparative Examples, "parts" and "%" indicate parts by weight and% by weight, respectively, unless otherwise specified. The dissolved oxygen concentration meter (manufactured by Toa Denpa Kogyo Co., Ltd.) was measured using a device in which the electrode was immersed in a 5% by weight aqueous sodium sulfite solution and the oxygen concentration was calibrated to 0 ppm. The glass transition temperature was determined by drying the ultrahigh molecular weight emulsion obtained in the production example at 105 ° C. for 1 hour, and measuring the obtained film with a differential scanning calorimeter (DSC, manufactured by Seiko Instruments Inc.).

The performance evaluation of the moisture-proof paper prepared in each of Examples and Comparative Examples was performed by the following method. "Moisture permeability": Performed according to JIS Z-0208 (cup method). In addition, the resin coating surface was set to the front side.

"Water disintegration (recyclability)": The moisture-proof paper obtained in each of Examples and Comparative Examples was cut into 2 cm squares by hand, water was added so that the concentration of the paper became 1%, and the cutting edge was rounded. Stir with a home mixer (9500 rpm) for 30 seconds,
Handmade sheets were obtained on a ppi paper machine. After air drying, the disintegration state of the resin was observed. ；: Completely disintegrated without resin film △: Residual resin film piece area 0.25 cm ² or less ×: Residual resin film piece area 0.25 cm ² or more

"Blocking resistance": The resin-coated side and the non-coated side were combined, left at a temperature of 60 ° C. under a load of 1.5 kg / cm ² for 1 week, and observed for blocking when the temperature was returned to room temperature. did. ；: No blocking at all △: lightly blocking but easily peeling off ×: completely blocking and not peeling off

Production Example 1 (Ultra High Molecular Weight Emulsion A) 140 g of water was placed in a 1 L five-necked separable flask equipped with a thermometer, a reflux condenser, a dropping funnel, a stirring rod, a nitrogen gas vent tube, and electrodes of an oximeter. Was charged. Next, 98.0 g of styrene and 9 methyl methacrylate were placed in a 1 L beaker.
7.0 g, 2-ethylhexyl acrylate 170.0
g, 7.2 g of 2-hydroxyethyl methacrylate, 10.0 g of methacrylic acid, 5.5 g of sodium dodecylbenzenesulfonate, and 120 g of water were charged and emulsified with a homomixer. Add 50-1 nitrogen gas to flask and emulsion
When the injection was performed at a flow rate of 00 ml / min, the dissolved oxygen concentration became 0 ppm in about 2 hours. Set the temperature of the flask to 3
After the temperature was raised to 5 ° C., the monomer emulsion, the polymerization initiator and the reducing agent were continuously added dropwise to start polymerization. The polymerization initiator was prepared by adding 0.3 g of t-butyl hydroperoxide to deoxygenated water 3
The solution was diluted with 0.0 g, and as a reducing agent, 0.3 g of sodium formaldehyde sulfoxylate was diluted with 25.0 g of deoxygenated water, and added dropwise continuously for 5 hours. The monomer emulsion was dropped continuously for 4 hours. During this time, the temperature of the system was maintained at 35 ± 3 ° C.
After completion of the dropwise addition of the polymerization initiator and the reducing agent, the mixture was kept at 35 ± 3 ° C. for 1 hour and aged. After cooling, 25% aqueous ammonia was added to neutralize. The obtained ultra high molecular weight emulsion had a nonvolatile content of 55.0%, a viscosity of 2000 mPa · s, a pH of 7.0,
Glass transition temperature was 20 ° C.

Production Example 2 (Ultra High Molecular Weight Emulsion B) Polymerization was carried out under the same conditions as in Production Example 1 except that the emulsifier was changed to 5.5 g of Aqualon HS-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.). The glass transition temperature of the obtained ultrahigh molecular weight emulsion was 22 ° C.

Production Example 3 (Ultrahigh Molecular Weight Emulsion C)
Polymerization was carried out under the same conditions as in Production Example 1 except that 0 g and 1.0 g of formaldehyde sulfoxylate sodium salt as a reducing agent were changed to 1.0 g. The glass transition temperature of the obtained ultrahigh molecular weight emulsion was 17 ° C.

Production Example 4 (Ultra High Molecular Weight Emulsion D) Polymerization was carried out under the same conditions as in Production Example 1 except that 179.5 g of styrene and 88.5 g of 2-ethylhexyl acrylate were used. In addition, the glass transition temperature of the obtained ultrahigh molecular weight emulsion was 60 ° C.

Production Example 5 (Ultra High Molecular Weight Emulsion E) Polymerization was carried out under the same conditions as in Production Example 1, except that 10.0 g of styrene and 258.0 g of 2-ethylhexyl acrylate were used. In addition, the glass transition temperature of the obtained ultrahigh molecular weight emulsion was -15 ° C.

Example 1 Paraffin wax emulsion EMUSTAR was added to 100 parts of the ultrahigh molecular weight emulsion A obtained in Production Example 1.
-0136 (Nippon Seiro Co., Ltd., nonvolatile content 40%) 3
Was added and stirred well to obtain a resin composition for moisture-proof paper of the present invention. This moisture-proof paper resin composition was prepared with a basis weight of 75 g / m ^2.
Was coated with a bar coater so that the solid content was 15 g / m ² . The drying conditions were 10
The test was performed at 5 ° C. for 30 seconds. Table 1 shows the composition of the ultrahigh molecular weight emulsion and the resin composition for moisture-proof paper, and the performance evaluation of the moisture-proof paper. The water vapor transmission rate of the present example is the water vapor transmission rate of a commercially available 10 μm polyethylene laminated paper (30 to 40 g / m 2).
² · 24hr) to be at the same level.

Example 2 Paraffin wax emulsion Prunit 1 was added to 100 parts of the ultrahigh molecular weight emulsion B obtained in Production Example 2.
01Z (Shin-Nakamura Chemical Co., Ltd., nonvolatile content 50%)
A moisture-proof paper was prepared in the same manner as in Example 1 except that 3 parts were added. Table 1 shows the composition of the ultrahigh molecular weight emulsion and the resin composition for moisture-proof paper, and the performance evaluation of the moisture-proof paper. In this embodiment, an anionic emulsifier which is an ethylenically unsaturated monomer is used, and high moisture permeability is obtained.

Comparative Example 1 A moisture-proof paper was produced in the same manner as in Example 1, except that the paraffin wax emulsion was changed to 0.8 part. Table 1 shows the composition of the ultrahigh molecular weight emulsion and the resin composition for moisture-proof paper, and the performance evaluation of the moisture-proof paper. In this comparative example, since the amount of the wax-based emulsion was small, the moisture permeability was low.

Comparative Example 2 A moisture-proof paper was produced in the same manner as in Example 1, except that the ultrahigh molecular weight emulsion C obtained in Production Example 3 was changed. The first was the evaluation of the blending state of the ultrahigh molecular weight emulsion and the resin composition for moisture-proof paper and the performance evaluation of the moisture-proof paper.
It is shown in the table. In this comparative example, a large amount of hydroperoxide as a polymerization initiator was used, so that the water disintegration property and the blocking resistance were reduced.

Comparative Example 3 A moisture-proof paper was produced in the same manner as in Example 1 except that the ultrahigh molecular weight emulsion D obtained in Production Example 4 was changed. The first was the evaluation of the blending state of the ultrahigh molecular weight emulsion and the resin composition for moisture-proof paper and the performance evaluation of the moisture-proof paper.
It is shown in the table. In this comparative example, the ultrahigh molecular weight emulsion has a too high glass transition temperature, so that the moisture permeability is deteriorated.

Comparative Example 4 A moisture-proof paper was prepared in the same manner as in Example 1 except that the ultrahigh molecular weight emulsion E obtained in Production Example 5 was changed. The first was the evaluation of the blending state of the ultrahigh molecular weight emulsion and the resin composition for moisture-proof paper and the performance evaluation of the moisture-proof paper.
It is shown in the table. In this comparative example, since the glass transition temperature of the ultrahigh molecular weight emulsion was too low, the water disintegration property and the blocking resistance deteriorated.

[0032]

[Table 1]

[0033]

As is clear from the above examples, by applying the resin composition for moisture-proof paper obtained according to the present invention to paper, high moisture-proof and waterproof properties are obtained, and water disaggregation at the time of recovery of used paper is performed. Moisture-proof paper having excellent properties, particularly excellent blocking resistance.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) D21H 19/22 D21H 19/22 (72) Inventor Hideo Takeuchi 16 Tatsunocho Hiyama, Tatsuno-shi, Hyogo F-term (reference) 4J002 AE03X BC03W BG01W BG06W BG07W GK04 HA06 4J011 KA06 KA09 KA25 4L055 AG51 AG63 AG71 AG89 AG97 AH23 AH37 AJ02 BE08 EA20 EA29 EA32 FA14 FA19 FA30 GA47

Claims (2)

[Claims] 1. A hydroperoxide and / or persulfate is used in an amount of 0.001 to 0.2 part by weight based on 100 parts by weight of an ethylenically unsaturated monomer, and the oxygen concentration of the aqueous phase of the reaction system is adjusted according to JIS K0102. Holding at 0 ppm by the measurement method, the glass transition temperature was obtained by emulsion polymerization by a redox reaction using a reducing agent and an emulsifier, and 100 parts by weight of an ultrahigh molecular weight emulsion having a glass transition temperature of −10 to 50 ° C. A resin composition for moisture-proof paper, containing 1 to 7 parts by weight of a system emulsion. 2. An ultra-high molecular weight emulsion containing an emulsifier in an amount of 0.1 to 100 parts by weight of a raw material ethylenically unsaturated monomer.
The resin composition for moisture-proof paper according to claim 1, which is obtained by emulsion polymerization using 5 to 3 parts by weight.