KR100525501B1 - Method for Preparing Molded Article Using Recycled Paper - Google Patents

Abstract

The present invention relates to a reinforcing composition added to improve the strength of a molded article produced using recycled paper as a main raw material, wherein the reinforcing composition is selected from the group consisting of styrene, carboxylic acid containing an ethylenically unsaturated group, and derivatives thereof. The selected monomer mixture is prepared by emulsion polymerization in an aqueous phase containing an emulsifier and a polymerization initiator, and the copolymer obtained as a result of the reaction has a glass transition temperature of 40 to 70 ° C. When the reinforcing composition is added to the production process of the molding using recycled paper, it has an advantage of obtaining excellent mechanical properties compared to the molding using a conventional recycled paper.

Description

Manufacturing method using recycled paper {Method for Preparing Molded Article Using Recycled Paper}

The present invention relates to reinforcing compositions of moldings using recycled paper. More specifically, the present invention relates to a reinforcing composition added to improve the strength of a molded article produced using recycled paper as a main raw material, and a method for producing a molded article using the same.

In the present invention, the recycled paper refers to a paper that is used again by dissociating the discarded paper from water after using newspaper, magazine, cardboard, etc. as waste paper and making it sludge.

Recently, as environmental awareness increases, efforts have been made to apply recycled materials to other useful uses, and the use of various recycled papers has been common. In addition, the technology for manufacturing recycled paper in the form of a molded article such as packaging containers of various products is also increasingly used in terms of environmental protection. For example, there has been proposed a method of forming a sludge into an egg packaging container, a board, etc. after sludged recycled paper. In the case of a typical egg packaging container using an recycled paper, a plurality of packaging containers are generally integrated as one type. It is molded to form an independent receiving space corresponding to each of the eggs. Conventionally, resin-based products molded in the above shape have been widely used, but it is difficult to effectively cope with environmental problems that may occur due to the use of resins, and demand for products using recycled paper is increasing. However, the egg contained in the lower container tends to be damaged by the load of the container placed on the upper side due to the distribution of the plurality of egg packaging containers overlapped with each other, and inadvertently dropped on the floor during handling. In this case, the packaging container itself is deformed, so that damage to the contents egg can not be avoided. In particular, in the case of using recycled paper, fibrous components such as cellulose contained before regeneration are damaged during regeneration, and the mechanical properties thereof are deteriorated. Thus, it is not possible to effectively prevent breakage of eggs due to external impact during distribution.

As such, moldings using recycled paper have low mechanical strength, and thus, a method of increasing the weight of the moldings or mixing high-quality paper or pulp has been proposed. In this regard, as a technique for regenerating cellulose from waste paper, for example, Korean Patent Publication No. 1999-82682 discloses a method for regenerating fibers from waste paper by loading waste paper and paper into a continuous bundle fiber regeneration apparatus. . However, the above technique was difficult to satisfy the mold conditions of the moldings, and it was difficult to keep the mixing ratio constant. In particular, manufacturing costs have risen, and the use of recycled paper does not meet the purpose of improving economics.

In addition, a method of improving strength characteristics by mixing additives during molding of recycled paper has been proposed. For example, Korean Patent Publication No. 1998-64993 mixes a small amount of PVC, PP or PE waste fibers into paper sludge obtained as a residue of a paper mill, and adds additives such as polyethylene resin, vinyl resin or urethane resin. To mold. In addition, Korean Patent Publication No. 1996-3188 contains copolymerized units of diallyldimethylammonium chloride, N-vinylamine or N-vinylimidazoline, and is converted into a cationic polymer and an aqueous solution having a K value of 30 or more. It is disclosed that a mixture of natural potato starch can be used to improve the mechanical properties of paper and paperboard using strength enhancers. However, the technique is still insufficient to meet the strength characteristics required for moldings using recycled paper.

Therefore, there has been a demand for a method for effectively improving the strength of moldings produced using recycled paper.

Accordingly, the present inventors, when adding a reinforcing composition emulsified and polymerized acrylic monomer and / or styrene into a copolymer having a specific glass transition temperature range in the process of producing a molding of recycled paper material, the mechanical problem that has been a problem in the prior art It was found that the problem of physical property degradation can be effectively solved.

Accordingly, it is an object of the present invention to provide a reinforcing composition that can be effectively added to the mechanical properties by adding in the manufacturing process of the molding using recycled paper.

Another object of the present invention is to provide a method for producing a molding using recycled paper by adding the reinforcing composition in a specific content.

In order to achieve the above object, the reinforcing composition of the molded article using recycled paper provided according to one embodiment of the present invention comprises a monomer mixture selected from the group consisting of styrene, carboxylic acid containing an ethylenically unsaturated group and derivatives thereof. It is produced by emulsion polymerization in an aqueous phase containing an emulsifier and a polymerization initiator, characterized in that the copolymer obtained as a result of the reaction has a glass transition temperature of 40 to 70 ℃.

Provided according to another embodiment of the present invention, a method for producing a molded article using recycled paper is 0.2 to 1.5 of the recycled paper sludge based on the solid content in the recycled paper sludge containing 0.5 to 4 parts by weight based on 100 parts by weight of water. After adding and mixing the reinforcing composition corresponding to the weight% by vacuum forming it and characterized in that it comprises the step of drying at 130 ~ 180 ℃.

The present invention can all be achieved by the following description.

As described above, the present invention relates to a reinforcing composition of a molding using recycled paper and a method for preparing a molding by adding the same, wherein the reinforcing composition has a glass transition temperature (T _g ) of about 40 to 70 ° C. in the dispersion. The copolymer is present in a dispersed state, and the polymerization is performed by emulsion polymerization, which is already well known in the art.

In general, in the case of emulsion polymerization, micelles are formed in an aqueous solution due to the hydrophilic and hydrophobic portions of the emulsifier, and the initiator is decomposed into radicals at the polymerization temperature and enters the micelles. At the same time, the monomer diffuses from the dispersed phase and enters the micelle to meet radicals and start the polymerization reaction. As the polymerization reaction proceeds, the monomer dispersed phase becomes smaller as the monomer is polymerized and diffused, and the micelles in which the polymerization takes place become larger and larger as polymer particles, thereby increasing the solid content.

As such, in the present invention, monomers, emulsifiers, water-soluble initiators and water (preferably deionized water as dispersion mediums) are essentially used, preferably 0.1 to 4 parts by weight of emulsifier and 0.05 to 2 initiators based on 100 parts by weight of the monomer mixture. Parts by weight are used, and the amount of water is preferably adjusted so that the solids content in the reinforcing composition is about 20-50%.

The monomer used in the polymerization reaction is in the form of a mixture in which two or more monomers are selected from the group consisting of styrene, a carboxylic acid containing an ethylenically unsaturated group and derivatives thereof, and particularly, an ester derivative may be used as a derivative of the carboxylic acid containing the ethylenically unsaturated group. desirable. Representative examples of such monomers include n-butyl acrylate, methyl methacrylate, styrene, methacrylate, methacrylic acid, acrylic acid, ethyl acrylate, 2-ethylhexyl acrylate, itaconic acid, 2-hydroxyethyl methacrylate. And lauryl methacrylate. The chemical formulas of typical monomers that can be used and the glass transition temperatures (T _g ) of these polymers are shown in Table 1 below.

Monomer Chemical formula Polymer glass transition temperature (℃) n-Butylacrylate CH ₂ = CH-COO- (n) C ₄ H ₉ -54 Methylmethacrylate CH ₃ ｜ CH ₂ = C-COOCH ₃ 105 Styrene CH ₂ = CH- 100 Methacrylate CH ₂ = CH-COOCH ₃ 10 Methacrylic acid CH ₃ ｜ CH ₂ = C-COOH 228 Acrylic acid CH ₂ = CH-COOH 106 Ethylacrylate CH ₂ = CH-COOC ₂ H ₅ -24 2-Ethylhexylacrylate CH ₂ = CHCOO-CH ₂ -CH-C ₄ H ₉ | C ₂ H ₅ -85

In the present invention, as an emulsifier added to provide a polymerization site, anionic, cationic and nonionic emulsifiers commonly known in the art may be used. Anionic emulsifiers include soap, LAS (linear alkylbenzenesulfonate), SLS (laurylsulfate salt), SLES (laurylethersulfate salt), DOS (dioctylsulfosuccinate salt), alkylpropylsulfosite Cationic emulsifiers include stearyltrimethyl ammonium salts, benzalkonium, and nonionic emulsifiers include NP (nonylphenol) or EO (ethylene oxide) adducts of lauryl alcohol. have. The emulsifier may be used in the form of a single substance or mixture depending on the reaction characteristics of the monomer mixture.

As described above, the emulsifier is used in the range of 0.1 to 4 parts by weight based on 100 parts by weight of the monomer mixture, if less than 0.1 parts by weight, the reaction is difficult to proceed, there is a problem such as the generation of lumps and the stability of the emulsion, exceeding 4 parts If there is a lot of bubbles in the manufacturing process there is a problem when using.

The polymerization initiator may be used without particular limitation as long as it is a kind capable of initiating free radical polymerization, for example, potassium persulfate, ammonium persulfate, organic peroxide, hydrogen peroxide, which are known in the art. , Redox system, and the like can be used. The polymerization initiator is used in the range of about 0.05 to 2 parts by weight with respect to 100 parts by weight of the monomer mixture, if less than 0.05 parts by weight is difficult to proceed the reaction, when it exceeds 2 parts by weight problems in the stability of storage after the reaction There is this.

In addition to the components mentioned above, one or two or more of the additives may be reacted with a chain-transfer agent such as alkyl mercaptan, an electrolyte such as carbonate, sodium hydroxide, neutralizing agent such as aqueous ammonia, buffer, reducing agent, other supplements, or the like. It may be used in an appropriate amount depending on the conditions, such additive components are known in the art. For example, the chain transfer agent (molecular weight regulator) is preferably used up to about 2 parts by weight based on 100 parts by weight of the monomer mixture and up to about 1 part by weight based on 100 parts by weight of the monomer mixture.

In the present invention, in order to effectively improve the mechanical properties of the molded article using recycled paper, it is particularly required that the copolymer dispersed in the reinforcing composition has a glass transition temperature range of 40 to 70 ° C. The reason for this is that the strength of the molded product is not reinforced significantly below 40 ° C., but rather the strength drops below 70 ° C. Therefore, it is important to adjust the ratio of each monomer content in the monomer mixture to have the glass transition temperature range.

According to the invention, the above-mentioned polymerization reaction may be a batch process or a continuous process, preferably a reaction temperature of about 60 to 85 ℃ and an inert atmosphere (for example, nitrogen gas Atmosphere), but the reaction is carried out in various ways such as batch method, monomer addition method, emulsion addition method, seed method, but can be generally carried out by the following two methods.

First, in the monomer addition method, an emulsifier, water, and a polymerization initiator are initially added to a reactor, and the monomer mixture is continuously added while reacting for about 2 to 4 hours. In this case, the polymerization initiator may be optionally dissolved in water in a separate vessel and continuously added to the reactor with the addition of monomer. The above method has the advantage of easy removal of heat of polymerization, stability of polymerization, and particle size control.

Secondly, after the monomer mixture is emulsified in the emulsifier dispersion by the emulsion addition method, a portion (around about 10% by weight of the total monomer mixture) is introduced into the reactor and polymerized, and then the remaining monomer emulsion is continuously or stepwise introduced for about 2 to 5 hours. This method has the advantage of easy removal of polymerization heat, and the particle size distribution is wider than that of the monomer addition method.

As described above, although various methods can be used in the present invention, the above-mentioned two methods which are widely used are preferable, and among them, polymerization is most preferred according to the monomer addition method.

As a result of the completion of the above-mentioned polymerization, the copolymer has a glass transition temperature (T _g ) of about 40 to 70 ° C. In addition, the weight average molecular weight of the copolymer is about 50,000 to 500,000, and the average particle diameter of the copolymer particles contained in the dispersion liquid is about 0.05 to 0.5 탆 (500 to 5,000 kPa). In addition, the reinforcing composition (dispersion) of the present invention is preferably to have a solid content of about 20 to 50%, which is a result of consideration of ease of manufacture, storage distribution problems, mixing with other supplements, and the like.

According to the present invention, the reinforcing composition prepared as described above is added in a certain amount in the process of forming the recycled paper, a general method for producing a molding using the recycled paper is already well known in the art.

More specifically, 0.5 to 4 parts by weight of regenerated species is sludged with respect to 100 parts by weight of water, and the regenerated species is added to and mixed with the reinforcing composition corresponding to about 0.2 to 1.5% by weight of sludge based on solids. After molding in vacuo, water is dried in a drying furnace at about 130 to 180 캜 to produce a product. If it is less than 0.2% by weight, there is a problem that the strength improvement is significantly low, and when it exceeds 1.5% by weight, it causes a rise in manufacturing cost. At this time, the reinforcing composition is uniformly dispersed and adsorbed in the paper (pulp) structure, and adhered in a drying furnace to improve the mechanical properties of the molding, accordingly, egg packaging container, paper molding cup, industrial material packaging container, packaging buffer, It can be applied to moldings of various uses such as corrugated cardboard.

The present invention can be more clearly understood by the following examples, which are only intended to illustrate the present invention and are not intended to limit the scope of the invention.

Example 1

Preparation of Reinforcement Composition

64 parts by weight of deionized water, 1 part by weight of an emulsifier (SLS) and 0.2 part by weight of a polymerization initiator (ammonium persulfate) were added into a reactor equipped with a circulation condenser and a stirrer, and the reactor was heated to 80 ° C. In a separate vessel, the monomer mixture consisting of 15 parts by weight of methyl methacrylate, 10 parts by weight of styrene and 10 parts by weight of n-butyl acrylate and 0.2 parts by weight of a chain transfer agent (lauryl mercaptan) are uniformly mixed, and then The reaction was carried out for 3 hours while stirring. At this time, the monomer mixture and the chain transfer agent were purged with nitrogen gas. After completion of the reaction the reactor contents were aged under stirring at 80 ° C. for 1 hour and then cooled to room temperature. The dispersion was then neutralized to pH 6.5 by addition of ammonia water.

The content of solids in the dispersion was 35.3%, the measured glass transition temperature of the copolymer was 58 ℃, the average particle diameter of the copolymer particles was 0.12㎛.

Example 2

38.2 parts by weight of deionized water and 0.7 parts by weight of emulsifier (SLES, NP 40 mol) were respectively added to the reactor to which the circulation condenser and the stirrer were attached, and the inside of the reactor was heated to 75 ° C. In a separate vessel, 0.2 parts by weight of a monomer mixture consisting of 28 parts by weight of methyl methacrylate, 12 parts by weight of n-butyl acrylate and 0.2 parts by weight of a chain transfer agent (lauryl mercaptan) were added dropwise into the reactor, and then another container. 0.2 part by weight of a polymerization initiator (ammonium persulfate) was dissolved in 20 parts of water well, and reacted under stirring for 3 hours while dropping together. At this time, the mixture of the monomer mixture and the chain transfer agent was purged with nitrogen gas. After the end of the reaction the reactor contents were aged under stirring at 75 ° C. for 1 hour and then cooled to room temperature. The dispersion was then neutralized to pH 6.5 by addition of ammonia water.

The content of solids in the dispersion was 41.5%, the measured glass transition temperature of the copolymer was 57 ℃, the average particle diameter of the copolymer particles was 0.081㎛.

Example 3

Manufacture of moldings

In the process of dissociating recycled paper according to KS M7030 or directly collecting dissociated sludge at the manufacturing site and adding a waterproofing agent before molding the paper sludge, the reinforcing composition prepared according to Example 1 was added and vacuum-molded in a constant mold. After drying and measuring the strength, but in order to increase the accuracy of the experiment in the process of directly injecting the waterproofing agent in the preparation of the reinforcing composition prepared according to Example 1 and sampled through a molding drying process. At this time, the input amount of the reinforcing composition prepared according to Example 1 in the range of 0.2 to 1.2% by weight of the paper in the paper sludge on a solid basis.

The molding was prepared as a sample according to the egg packaging container test method of KS M 7613, the strength of the sample was also measured by the method described above, the strength according to the content is shown in Table 2 below.

Composition input amount (% by weight) Strength (kgf) 0 180 0.2 185 0.4 230 0.6 320 0.8 420 1.0 540 1.2 620

Example 4

A reinforcing composition was prepared in the same manner as in Example 2, except that 35 parts by weight of the monomer mixture consisting of methyl methacrylate and n-butyl acrylate were used. At this time, the mixing ratio of methyl methacrylate and n-butyl acrylate in the monomer mixture was changed. In addition, the reinforcing composition prepared as described above was added to the paper sludge in an amount of 0.6% by weight of the paper contained in the paper sludge on a solid basis, and the strength was measured after molding in the same manner as in Example 3. Glass transition temperature and strength measurement results according to the mixing ratio of methyl methacrylate and n-butyl acrylate are shown in Table 3 below.

Monomer compounding ratio T _g (℃) Strength (kgf) Composition added amount (% by weight) 180 0 50/50 25 180 0.6 60/40 41 200 0.6 65/35 49 250 0.6 70/30 57 350 0.6 75/25 64 380 0.6 80/20 72 180 0.6

When the reinforcing composition according to the present invention is added in the manufacturing process of a molding using recycled paper, it has an advantage of effectively preventing the strength degradation phenomenon which has been a problem in the prior art.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of the present invention will be apparent from the appended claims.

Claims (14)

To the recycled paper sludge containing 0.5 to 4 parts by weight of regenerated paper based on 100 parts by weight of water was added to mix the reinforcement composition corresponding to 0.2 to 1.5% by weight of the recycled paper sludge on a solid basis, followed by vacuum forming and 130 to 180 Drying at 캜; The reinforcing composition is prepared by emulsion polymerization of a monomer mixture of two or more selected from the group consisting of styrene, carboxylic acid containing an ethylenically unsaturated group and derivatives thereof in an aqueous phase containing an emulsifier and a polymerization initiator, Method for producing a molded article using recycled paper, characterized in that the copolymer has a glass transition temperature of 40 ~ 70 ℃. The method of claim 1, wherein the emulsifier and the polymerization initiator is used in 0.1 to 4 parts by weight and 0.05 to 2 parts by weight, respectively, based on 100 parts by weight of the monomer mixture in the emulsion polymerization. Way. The method of claim 1, wherein the monomer is n-butyl acrylate, methyl methacrylate, styrene, methacrylate, methacrylic acid, acrylic acid, ethyl acrylate, 2-ethylhexyl acrylate, itaconic acid, 2-hydroxyethyl Method for producing a molded article using recycled paper, characterized in that selected from the group consisting of methacrylate and lauryl methacrylate. The method of claim 1, wherein the emulsifier is selected from one or two or more from anionic, cationic and nonionic emulsifiers. The method of claim 4, wherein the anionic emulsifier is soap, LAS (linear alkylbenzenesulfonate), SLS (lauryl sulfate salt), SLES (lauryl ether sulfate salt), DOS (dioctylsulfosuccinate salt) or alkyl Propylsulfosuccinate salt, the cationic emulsifier is stearyltrimethyl ammonium salt or benzalkonium, and the nonionic emulsifier is NP (nonylphenol) or EO (ethylene oxide) adduct of lauryl alcohol. Method for producing a molded article using recycled paper.  The method of claim 1, wherein the polymerization initiator is selected from the group consisting of potassium persulfate, ammonium persulfate, organic peroxide, hydrogen peroxide, and redox system, Method for producing a molded article using recycled paper. The method of claim 1, wherein the reinforcing composition further comprises at least one additive selected from the group consisting of a chain transfer agent, an electrolyte, a neutralizing agent, a buffer, a reducing agent, and a supplement. . The method of claim 7, wherein the chain transfer agent is used up to 2 parts by weight based on 100 parts by weight of the monomer mixture, the electrolyte is used up to 1 part by weight based on 100 parts by weight of the monomer mixture, using recycled paper Method of Preparation of Molded Products. The method according to claim 1, wherein the copolymer has a weight average molecular weight of 50,000 to 500,000 and an average particle diameter of 0.05 to 0.5 mu m. The method of claim 1, wherein the emulsion polymerization reaction is performed by adding the emulsifier, water, and a polymerization initiator to a reactor and continuously adding the monomer mixture. The method of claim 1, wherein the emulsion polymerization is carried out at a temperature of 60 to 85 ℃. The method according to claim 1, wherein the content of solids in the reinforcing composition is 20 to 50%. delete The method according to claim 1, wherein the molded article is an egg tray.