JPH0577685B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing a novel conjugated diene polymer latex, and more specifically, conjugated diene,
Ethylenically unsaturated acid and aromatic vinyl monomer are essential components, and as polymerization initiators, an organic type is used in the first stage and an inorganic type is used in the second stage, and is useful as a binder obtained by emulsion polymerization. The present invention relates to a method for producing a novel copolymer latex. (Prior Art) Conventionally, it has been used as a binder for coated paper, a binder for binding fibers such as nonwoven fabrics and artificial leather, a binder for carpet backing, a pigment binder for paints, and an adhesive for various materials.
Various synthetic latexes have been used, including natural rubber latex. These binders are required to have excellent adhesive strength, water resistance, and resistance to blistering due to heating such as drying. For example, carboxy-modified butadiene-styrene copolymer latex has traditionally been used for coated paper, either alone or with casein, protein, etc.
It is widely used as a binder for pigment coating processing of paper in combination with natural or synthetic binders such as starch and polyvinyl alcohol. Pigment-coated paper (coated paper) treated with paper coating compositions containing these carboxy-modified butadiene-styrene copolymer latexes has excellent properties such as whiteness and gloss, and is used in large quantities for various purposes. has been done. In recent years, demand for coated paper has increased significantly.
With the recent rapid increase in the number of printed materials, especially with the trend toward higher speed printing in offset printing, the following properties are now required of pigment-coated papers and pigment binders for offset printing. One of these properties is that it resists the mechanical force applied to the pigment-coated paper surface during printing, preventing the pigment from falling off and the coating layer from peeling off from the base paper, thereby enabling beautiful printing. For this purpose, it is necessary that the adhesion between the pigment particles and between the pigment coating layer and the base paper serving as its support be strong. The higher the printing speed, the more this kind of damage to the paper surface occurs.
Also, the greater the number of times the coating is applied, the more intense the coating becomes. Therefore, a coated paper that can withstand this is required, but for this purpose, the pigment binder used must be
It must have excellent adhesive strength (referred to as dry strength). Another property is water resistance. Offset printing uses a "dampening water" unique to the printing method, but it is required to have the strength to withstand the mechanical force of printing when damp, that is, to have water resistance (also called wet strength). be done. Another property is blister resistance. In particular, in the case of rotary offset printing, due to the nature of the printing method, "blisters" are likely to occur due to the high temperature and high speed drying after high speed printing.
If this blistering occurs, the commercial value of the printing paper will be greatly impaired. The pigment binder is a major cause of this blistering, so
The pigment binder used is required to have good blister resistance. One of these is the increasing speed of printing, which requires even better ink receptivity than in the past. The above has described the problems with coated paper in offset printing, but these problems are required not only in offset printing but also in other printing methods. As described above, coated paper is required to have properties such as water resistance, ink receptivity, dry strength, and blister resistance, but there is no conventional coated paper that has a high level of balance in all of these properties. Nakatsuta. The reason for this is that water resistance and ink receptivity are contradictory properties, and dry strength and blister resistance are similarly contradictory properties. Conventionally, as a method of improving water resistance, a method of lowering the gel content of a synthetic binder is known, but lowering the gel content lowers ink receptivity. On the other hand, as a method for improving ink receptivity, it is known to increase the particle size or glass transition temperature of the synthetic binder, but this method lowers water resistance. As a method of improving blisters, a method of lowering the gel content is known, but this has the technical difficulty of reducing dry strength. (Problems to be Solved by the Invention) The present inventors have developed a copolymer latex that has a high level of balance in performance such as water resistance, ink receptivity, dry strength, and blister resistance as a binder for coated paper. As a result of repeated studies, we have found that a new copolymer latex, which is made by emulsion polymerizing specific monomer components using organic and inorganic initiators, and has a gel content and glass transition temperature within a specific range, is water resistant. ,
It was discovered that this is a binder for coated paper that has a high balance of performance such as ink receptivity, dry strength, and blister resistance. Furthermore, it has been discovered that this copolymer latex has excellent water resistance, adhesive strength, and blister resistance, and is useful in the various binder applications described above, and the present invention has been completed. (Means for solving the problem) The present invention comprises 20 to 70% by weight of a conjugated diene monomer,
In emulsion polymerization of 0.5 to 10% by weight of ethylenically unsaturated acid monomers, 10 to 50% by weight of aromatic vinyl monomers, and 0 to 69.5% by weight of other copolymerizable monomers, (a) total 20 to 97% by weight of the monomers are reacted using an organic initiator, and (b) the remaining monomers are reacted with an inorganic compound in the presence of the copolymer latex of (a). The copolymer latex obtained by carrying out the reaction using a system initiator has a toluene insoluble content of 20 to 95% by weight, and the glass transition temperature of the copolymer component is 50°C or less (low temperature side). The present invention provides a method for producing a copolymer latex. The present invention will be explained in detail below. (1) Description of monomer components of the copolymer latex of the present invention Among the monomers used for producing the copolymer latex of the present invention, the conjugated diene monomers include:
For example, butadiene, isoprene, 2-chloro-
Examples include 1,3-butadiene and 2-methyl-1,3-butadiene. These can be used alone or in combination of two or more.
Preferred is butadiene. The proportion used is in the range of 20 to 70% by weight of the total monomers in order to provide the copolymer with appropriate elasticity and film hardness, and if it is less than 20% by weight, adhesive strength cannot be obtained. On the other hand, if it exceeds 70% by weight, water resistance will be poor. The preferred proportion used is 30-65% by weight. Examples of the ethylenically unsaturated acid monomer include mono- or dicarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid. Furthermore, anhydrides of dicarboxylic acids can also be used. These can be used alone or in combination of two or more. The proportion used is in the range of 0.5 to 10% by weight based on the total monomers; if it is less than 0.5% by weight, the adhesive strength and mechanical stability of the copolymer latex will decrease;
If it exceeds % by weight, the viscosity of the copolymer latex increases, making it difficult to handle and reducing operability. The preferred usage ratio is 1
~7% by weight. Examples of aromatic vinyl monomers include styrene, α-methylstyrene, vinyltoluene, p-
Examples include methylstyrene, and styrene is preferred. The proportion of aromatic vinyl monomer used is 10 out of the total monomers.
~50% by weight. Aromatic vinyl monomers provide water resistance, which is an important performance during offset printing.
If it is less than 10% by weight, water resistance will decrease, while if it exceeds 50% by weight, dry strength will decrease. Preferably it is 10 to 45% by weight. Typical examples of other monomers that can be copolymerized with the above monomers include methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxy methacrylate, and glycidyl methacrylate. Alkyl esters of acrylic acid or methacrylic acid such as acrylamide, acrylamide of ethylenically unsaturated carboxylic acids such as methacrylamide, N-methylolacrylamide,
Examples include vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, and vinyl carboxylic acid esters such as vinyl acetate. These can be used alone or in combination of two or more. These other copolymerizable monomers are used in an amount of 0 to 69.5% by weight based on the total monomers in order to impart appropriate hardness, elasticity, and water resistance to the copolymer. The preferred usage ratio is 0 to
It is 49% by weight. Printing gloss is improved when acrylonitrile is used in an amount of 1 to 20% by weight based on the total monomers. Compared to the copolymer latex using acrylonitrile in conventional polymerization methods, the copolymer latex of the method of the present invention has
The latex itself is less likely to be colored, and has a great effect of improving printing gloss. (2) Description of the method for producing a copolymer latex The method for producing a copolymer latex of the present invention involves converting 20 to 97% by weight of the above-mentioned monomers into an organic initiator. This is a two-stage polymerization method in which emulsion polymerization is carried out using an inorganic initiator, and then the remaining monomers are polymerized using an inorganic initiator. Examples of organic initiators include organic peroxide initiators such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, and benzoyl peroxide, and azo initiators such as azobisisobutyronitrile. Can be mentioned. These organic initiators can be used alone or in combination of two or more. Organic hydroperoxides can be used alone, but in order to increase the catalytic activity, they can be used in redox systems in combination with reducing agents, such as sugar-containing pyrophosphoric acid formulations and sulfoxylate formulations. The preferred amount of organic initiators used is 0.01 to 2 parts by weight for organic peroxide initiators, while 0.05 to 5 parts by weight for other initiators. Monomers that react with organic initiators account for 20% of the total monomers.
~97% by weight. If it is less than 20% by weight, ink receptivity and blister resistance will be poor. On the other hand, if it exceeds 97% by weight, dry strength, wet strength, and blister resistance are low. Preferably it is 30 to 95% by weight. The toluene-insoluble content of the copolymer obtained in the first step of reacting with an organic initiator is preferably 80% by weight or less, more preferably 70% by weight or less. 80
If it exceeds % by weight, dry strength, water resistance, and blister resistance decrease, which is not preferable. The toluene insoluble content of the present invention was measured by the following method. After adjusting the latex to pH 8 and coagulating the copolymer in the latex with isopropanol, washing,
The weight ratio of the remaining solid content to the total solid content obtained by immersing 0.3 g of the dried solid content in 100 c.c. of toluene at room temperature for 20 hours and then filtering it through a 120-mesh wire mesh. The toluene insoluble content can be adjusted by appropriately controlling the type and amount of the polymerization chain transfer agent, the type and amount of the ethylenically unsaturated acid monomer, the type and amount of the polymerization initiator, the polymerization temperature, etc. can. The glass transition temperature (Tg) of the copolymer component in the copolymer latex is 50°C or lower, preferably 45°C or lower, and more preferably 40°C or lower. Tg is 50℃
If it exceeds this, the adhesive strength will be poor. The Tg of the copolymer can be determined using the following formula. Therefore,
Type of monomer to obtain the desired Tg copolymer,
The composition ratio can be determined using the calculation formula. The glass transition point of the copolymer in the copolymer latex is a value calculated from the following formula. 1/Hg=W(1)/Tg(1)+W(2)/Tg(2)+W(3)/Tg(3)
+... Here, W(1) = Weight fraction of monomer (1) in the copolymer W(2) = Weight fraction of monomer (2) in the copolymer W(3) = Weight fraction of monomer (3) in the copolymer Tg(1) = Value of Tg of the homopolymer of monomer (1) expressed in absolute temperature Tg(2) = Monomer (2) ) Tg of the homopolymer of monomer (3) expressed in absolute temperature Tg (3) = Tg of the homopolymer of monomer (3) expressed in absolute temperature Tg = Tg of the copolymer expressed in absolute temperature The glass transition points (expressed in absolute temperature) of typical monomer homopolymers used in the present invention are as follows. Poly-3-butadiene = 170〓 Polystyrene = 373〓 Polymethyl methacrylate = 378〓 Polyacrylonitrile = 403〓 Polyacrylic acid = 379〓 Itanconic acid = 438〓 (Decomposition temperature) Each monomer used in the present invention The preferred distribution of the first stage step of reacting with an organic initiator and the second stage step of reacting with an inorganic initiator is as follows. For conjugated diene monomers, 1st step/2
Stage step = 10 to 100/0 to 90% by weight, and for the ethylenically unsaturated acid monomer, the distribution ratio of the first stage step/second stage step can be used without particular limitation. For the aromatic vinyl monomer, the ratio is 1st step/2nd step=0 to 80/100 to 20% by weight. Examples of inorganic initiators include potassium persulfate, ammonium persulfate, sodium peroxide, and hydrogen peroxide. Preferably, the solubility in water at 25°C is 1% by weight or more. Particularly preferred are persulfates. The preferred amount of the inorganic initiator used is 0.05 to 5 parts by weight per 100 parts by weight of the remaining monomer. The toluene insoluble content of the copolymer in the final copolymer latex is from 20 to 98% by weight, preferably from 30 to 95% by weight. If the toluene insoluble content is less than 20% by weight, dry strength and wet strength will decrease, while if it exceeds 98% by weight, dry strength, wet strength and blister resistance will decrease. The preferred average particle diameter of the copolymer latex of the present invention is 800 to 3000 Å. Within this range, the desired effects of the present invention can be achieved at a high level. Examples of the method for adding monomers for producing the copolymer latex of the present invention include the following method. (1) 20 to 97% by weight of total monomers as the first stage of reaction
The corresponding monomer and organic initiator, or only the monomer, are charged in advance into a reaction vessel. When only the monomer is charged, an organic initiator is added to it continuously, batchwise, sequentially, or a combination thereof to carry out the reaction, and then the remaining monomer and the inorganic initiator are added. is added to complete the reaction. The remaining monomers and inorganic initiator are added continuously, batchwise, sequentially, a combination thereof, or all at once. (2) As the first stage of the reaction, some monomers and an organic initiator or only an organic initiator are charged into the reactor in advance, and a predetermined amount of the monomer mixture is added to this continuously, batchwise, or sequentially. Alternatively, the reaction is carried out by adding them all at once or by a combination thereof, and then the remaining monomers and the inorganic initiator are added all at once or by the addition method of the first stage reaction to complete the reaction. (3) Charge all the monomers into a reactor, first react 20 to 97% by weight of the total monomers using an organic initiator,
Next, the remaining monomers are reacted with an inorganic initiator to complete polymerization. The polymerization reaction of the present invention is carried out under normal pressure or increased pressure for 5 to 90 minutes.
It can be carried out at a temperature of about °C. The following emulsifiers and polymerization chain transfer agents are used as polymerization chemicals in the polymerization reaction. As the emulsifier, for example, an amphoteric surfactant, an anionic surfactant or a nonionic surfactant can be used. Examples of amphoteric surfactants include those having carboxylates, sulfate ester salts, sulfonates, and phosphate ester salts as anionic moieties, and amine salts and quaternary ammonium salts as cationic moieties. Examples of alkyl betaine salts include lauryl betaine, stearyl betaine, and 2-undecyl-hydroxyethylimidazolium betaine; amino acid types include lauryl-β-alanine, stearyl-β-alanine, and lauryl di(aminoethyl ) Glycine and dioctyldi(aminoethyl)glycine. Examples of the anionic surfactant include sulfuric esters of higher alcohols, alkylbenzene sulfonates, aliphatic sulfonates, dialkyl sulfosuccinates, and alkylnaphthalene sulfonates. Further, as the nonionic surfactant, common polyethylene glycol alkyl ester type, alkyl ether type, alkyl phenyl ether type surfactants, etc. are used. Further, as a typical example of a polymerization chain transfer agent, t-
Examples include mercaptans such as dodecyl mercaptan, n-dodecyl mercaptan and mercaptoethanol, terpene mixtures consisting of terpinolene, dipentene, t-terpine and small amounts of other cyclic terpenes, and halogenated hydrocarbons such as chloroform and carbon tetrachloride. I can do it. When the copolymer latex produced by the method of the present invention is used as a binder, it has a high balance of physical properties such as adhesive strength, water resistance, and blister resistance. It is useful as a binder for binding fibers such as fibers and artificial leather, a binder for carpet backing, a pigment binder for paints, and an adhesive for various materials. When the copolymer latex produced by the method of the present invention is used as a binder for coated paper,
Compared to conventional copolymer latexes, it has a much higher balance of physical properties such as adhesive strength, water resistance, ink receptivity, and blister resistance for coated paper, and is therefore particularly suitable as a binder for coated paper. . The composition for coated paper will be explained below. The copolymer latex of the present invention is prepared as an aqueous dispersion with an inorganic pigment or an organic pigment, preferably an inorganic pigment, and, if necessary, other binders. At this time, for 100 parts by weight of pigment in terms of solid content,
The amount of the copolymer latex of the present invention is 5 to 40 parts by weight, preferably 9 to 30 parts by weight, and the amount of other binders is 0 to 30 parts by weight, preferably 2 to 10 parts by weight. Examples of pigments include inorganic pigments such as kaolin clay, talc, barium sulfate, titanium oxide (rutile anatase), calcium carbonate, aluminum hydroxide, zinc oxide, and satin white, and organic pigments such as polystyrene latex. , these may be used alone or in combination. Other binders used include natural binders such as starch, oxidized starch, soybean protein, and casein, or synthetic latexes such as polyvinyl alcohol, polyvinyl acetate latex, acrylic latex, and butadiene-methyl methacrylate latex. Ru. In preparing the paper coating composition of the present invention, other auxiliary agents such as dispersants (sodium pyrophosphate, sodium hexametaphosphate, etc.), antifoaming agents (polyglycols, fatty acid esters, phosphate esters, silicon oil, etc.), leveling agents (rot oil, dicyandiamide, urea, etc.), preservatives, water-resistant agents (formalin, hexamine, melamine resin, urea resin, glyoxal, etc.), mold release agents (calcium stearate, paraffin emulsion, etc.), Fluorescent dyes and color water retention improvers (carboxymethyl cellulose, sodium alginate) are added as necessary. The paper coating composition of the present invention can be applied to coated paper using known techniques such as air knife coater, blade coater, gate roll coater, etc.
This is done using a coating machine such as a roll coater.
After application, the surface is dried and finished by calendering, etc. It is used as general coated paper such as art paper, coated paper, lightweight coated paper, lightly coated paper, coated paperboard, and printing coated paper. Examples The parts and percentages shown below are by weight. 1 The manufacturing method of latex for paper coating in Examples and Comparative Examples will be explained. Method for producing latexes (A) to (E) The monomers of the first stage components shown in Table 1, emulsifiers, molecular weight regulators, and water were charged into a 10 stirring autoclave, and the temperature was raised. When the indicated polymerization temperature is reached, add an organic initiator and a polymerization reaction activator,
The jacket temperature is the same as the polymerization initiation temperature.
Polymerization was carried out for the time indicated in 1. Next, Table-1
Add the monomers of the second stage components shown in Table 1 and water, raise the temperature, and when the polymerization initiation temperature shown in Table 1 is reached, add the inorganic initiator, and keep the jacket temperature at the same temperature as the polymerization initiation temperature. Polymerization was carried out for the times shown in Table 1. Method for producing latex (Wa) Add the monomers shown in Table 2, an emulsifier, a molecular weight regulator, and water to a 10-liter autoclave with stirring.
℃, add an organic initiator and a polymerization reaction activator, keep the jacket temperature constant at 35℃, and when the polymerization conversion reaches 70%, add potassium persulfate.
Polymerization was carried out at a jacket temperature of 65°C for 6 hours. Method for producing latexes (a) to (e) Latexes were prepared according to the monomers, molecular weight regulators, initiators, polymerization reaction activators, emulsifiers, and polymerization conditions shown in (a) to (e) in Table 2. Latexes (a) to (e) were produced in the same manner as in (a). Glass transition temperature of latex (a) to (e), (a) to (e) As a result of calculating the glass transition temperature using the method shown in the text, latex (a) to (y) are -39℃ to +30℃,
(a) to (g) were in the range of -37°C to +65°C. (2) Method for evaluating physical properties of coated paper Paper coating compositions were prepared using the latexes shown in Tables 1 and 2 according to the following formulation. Copolymer latex 10 parts clay (0.5 parts sodium pyrophosphate as a dispersant)
%) 80 parts calcium carbonate 10 parts oxidized starch 5 parts water (added so that the solid content was 60%) The obtained composition was coated on a 64 g/m ² coated base paper using a coating blade. Work amount: 20g/m ²
Coating was performed to obtain coated paper. The obtained coated paper was tested according to the following evaluation method. Dry strength: index of adhesive strength The degree of picking when printed with an RI printing machine was visually determined and evaluated using a 5-step method. The higher the score, the better the adhesive strength. It is shown as the average value of 6 measurements. Wet strength: An indicator of water resistance. Visually judge the degree of dampening when dampening water is applied using a Molton roll on an RI printing machine.
Evaluation was made using a 5-step method. The higher the score, the better the wet strength. It is shown as the average value of 6 measurements. Blister resistance A paper coated on both sides is humidity-controlled (approximately 6%) and thrown into a heated oil bath, and the lowest temperature at which blisters occur is shown. The higher the temperature, the better the blister resistance. Ink receptivity Measured using the same method as wet strength, but
Printing was performed using ink with a much lower tack value than in the case of wet strength measurement so as not to cause scratches, and the state of ink transfer was visually compared and judged.
Evaluation points were given in the same way as RI Bitsk. Description of Examples and Comparative Examples Each Example and Comparative Example will be described below. Tables 3 and 4 show the characteristics of the copolymer latex used in each Example and Comparative Example and the results of evaluating the physical properties of coated paper. Examples 1, 2, 3, 4, 5 The copolymer latex used in Examples 1, 2, and 3 was prepared in the first stage using a polymerization recipe in which the amount of butadiene in the total monomer was 50%. Polymerization reaction monomer/2
This is a copolymer latex obtained by varying the ratio of the polymerization reaction monomers in the step within the range of the present invention, and the polymer latex (a) of Example 1: 60/40 (%) Example 2 Polymer latex (b) of Example 3: 70/30 (%) Polymer latex (c) of Example 3: 90/10 (%). In both cases, the latex that is the object of the present invention is produced. On the other hand, Examples 4 and 5 used a polymerization recipe in which the amount of butadiene in the total monomers was 40%, and the copolymer latex (d) of Example 4:
70/30 (%) Copolymer latex of Example 5 (E):
These are copolymer latexes obtained under conditions of 90/10 (%), and both latexes are produced as the object of the present invention. Examples 6 and 7 The copolymer latex of Example 2 was obtained by varying the amount of ethylenically unsaturated acid used in the present invention within the range of the present invention.
Instead of (b) acrylic acid/itaconic acid = 1/3 (%), in the copolymer latex (f) of Example 6, acrylic acid/itaconic acid = 1/1 (%), and the copolymer of Example 7 For the combined latex (g), a copolymer latex was obtained with itaconic acid = 1%. In both cases, the latex targeted by the present invention was obtained. Examples 8, 9, 10 The copolymer latexes of Examples 8, 9, and 10 were prepared by using the following initiator within the scope of the present invention in place of the initiator of the copolymer latex (b) of Example 2. A copolymer latex was obtained. Copolymer latex of Example 2 (B): yumene hydroperoxide/potassium persulfate Copolymer latex of Example 8 (H): Diisopropylbenzene hydroperoxide/potassium persulfate Copolymer latex of Example 9 (l): Azobisisobutritonitrile/potassium persulfate Copolymer latex of Example 10 (l): Qiumene hydroperoxide/hydrogen peroxide Both of these latexes are produced as the object of the present invention. Examples 11 and 12 The copolymer latexes of Examples 11 and 12 were prepared by varying the molecular weight regulator used during polymerization of the copolymer latex of Example 2, thereby reducing the toluene insoluble content of the final copolymer according to the present invention. These are copolymer latexes with various variations within the range of . Toluene-insoluble content of the final copolymer of copolymer latex (b) of Example 2: 90 Toluene-insoluble content of Example 11 95 Toluene-insoluble content of Example 12 24 Both are the object of the present invention Latex is manufactured. Example 13 The copolymer latex of Example 13 was prepared by first charging all the other compounds except the initiator into a reactor using the polymerization recipe of the copolymer latex (b) of Example 2. A polymerization reaction was started with an oxide initiator, and when the polymerization conversion rate was 80%, potassium persulfate was added to complete the polymerization, thereby obtaining a copolymer latex (wa). A latex which is the object of the present invention has been produced. Example 14 30 parts of butadiene, 28 parts of styrene, and 2 parts of itaconic acid were used in place of the monomer component in the first stage of copolymer latex (a), and 20 parts of butadiene was added in place of the monomer component in the second stage. Polymerization was carried out using 17 parts of styrene and 3 parts of acrylic acid under the same conditions as for copolymer latex (a), resulting in a toluene insoluble content of 80% and a glass transition temperature of -39.
A copolymer latex (F) at ℃ was obtained. 10 parts of butadiene, 30 parts of styrene, 17 parts of methyl methacrylate, 2 parts of itaconic acid, 1 part of acrylic acid in place of the first stage monomer components of copolymer latex (a)
part, and then butadiene in place of the second monomer component.
10 parts, 15 parts of styrene, 13 parts of methyl methacrylate,
Using 1 part of itaconic acid and 1 part of acrylic acid, polymerization was carried out under the same conditions as for copolymer latex (a), and a copolymer latex (y) with a toluene insoluble content of 80% and a glass transition temperature of 30°C was obtained. Ta. The following describes the evaluation of the physical properties of carpet backing compositions using copolymer latexes (F) and (Y) as binders. Preparation of carpet backing composition Next, using the copolymer latex thus obtained, a carpet backing composition was obtained according to the following formulation, and various carpet tests were conducted using this composition. The results are shown in Table 2. Formula (parts) Copolymer latex 100 Potassium pyrophosphate 0.8 Styrenated phenol 1.0 Heavy calcium carbonate 450 Thickener (sodium polyacrylate) 1.0 The carpet backing composition is prepared using copolymer latex. After adding a dispersing agent such as potassium pyrophosphate, and adding a filler such as heavy calcium carbonate, the solid content concentration is 75% and the viscosity is approximately 30,000 cps (Burtzkfield viscometer, BM type). No. 4 (measured at 6 rpm) using a thickener and water. (1) Peel strength Measured according to JIS L-1021 rug test method.
That is, a backing composition with a solids concentration of 75% was applied to a gray cloth made by tufting nylon crimped yarn onto a temporary base fabric made of polypropylene, and then a 7-osys jute was crimped as a secondary base fabric, and the lining was heated at 20°C. After drying for x20 minutes, the peel strength of the secondary base fabric and gray fabric was measured. (2) Water resistance The test piece shown in (1) above was left in water for 24 hours, and then the peel strength shown in (1) was measured. (3) Blister resistance Undried carpet at a temperature of 150℃ and a wind speed of 8m/sec
The samples were placed in a hot-air dryer adjusted to 100%, and the blisters that formed during drying were visually observed and determined. Judgment was made on a scale of 1 to 5. 1
Grade 5 means that no blisters occur at all, and grade 5 means that blisters occur all over the surface. The evaluation results for copolymer latex (F) and (Y) are that the peel strength is 4.2 and 3.8 Kg/5cm, and the water resistant peel strength is 3.4.
and 3.6 kg/5 cm, and the blister resistance was both first grade, and a carpet backing composition with excellent adhesive strength, water resistance, and blister resistance was obtained. Comparative Examples 1 and 2 The copolymer latexes of Comparative Examples 1 and 2 were prepared using the polymerization recipe of the monomer latex (b) of Example 2.
The product was produced under conditions in which the ratio of the stage polymerization reaction monomer/second stage polymerization reaction monomer was outside the scope of the present invention. Copolymer latex (b) of Example 2:
70/30 (%) Copolymer latex (a) of Comparative Example 1:
15/85 (%) Copolymer latex (b) of Comparative Example 2:
100/0 (%) In Comparative Example 1: The amount of the second stage monomer reacted with the inorganic initiator was too large, resulting in good ink, ink receptivity,
Blister resistance has not been developed. In the comparative example: the amount of monomer in the first stage reacted with the organic initiator was too large, making it impossible to obtain a product with good dry strength, wet strength, and blister resistance. Comparative Examples 3, 4 The copolymer latexes of Comparative Examples 3, 4, and 5 were prepared by replacing the initiator of the copolymer latex (b) of Example 2 with
A copolymer latex was prepared using an initiator outside the scope of the present invention as described below. Copolymer latex of Example 2 (b): (1st stage initiator) cumene hydroperoxide/(2nd stage initiator) Potassium persulfate Copolymer latex of Comparative Example 3 (c): ( 1st stage initiator) potassium persulfate/(2nd stage initiator) potassium persulfate Copolymer latex (d) of Comparative Example 4: (1st stage initiator) cumene hydroperoxide/(2 Stage initiator) Qiumene hydroperoxide Comparative Example 3: Since both the first stage and second stage were reacted with an inorganic initiator, a product with good blister resistance could not be obtained. Comparative Example 4: Because both the first and second stages were reacted with an organic initiator, a product with good dry strength and wet strength could not be obtained. Comparative Example 5 The copolymer latex (e) of Comparative Example 5 has a toluene insoluble content of 10% in the final copolymer, which is outside the range of the present invention, and has low dry strength and wet strength. Comparative Example 6 The final copolymer obtained in Comparative Example 6 has an oleene-insoluble content of 98%, which is outside the scope of the present invention, and has good dry strength, wet strength, and good blister resistance. What you have, you don't get. Comparative Example 7 The monomers of copolymer latex (a) were changed as shown below, and polymerization was carried out under the same conditions as in (a) except for a copolymer latex with a toluene insoluble content of 80% and a glass transition temperature of 65°C ( G) was obtained. Copolymer latex (A) 1st monomer, butadiene 30 (parts) Methyl methacrylate 5 Acrylonitrile 14 2nd monomer, butadiene 20 Styrene 11 Methyl methacrylate 7 Copolymer latex (G) 1st monomer Butadiene 10 (parts) Styrene 29 Methyl methacrylate 5 Acrylonitrile 14 Itaconic acid 2 Acrylic acid 0 Second monomer Butadiene 5 Styrene 31 Methyl methacrylate 7 Itaconic acid 1 Acrylic acid 1 Coated paper physical properties evaluation was as in Example 1. It was conducted under the same conditions. Dry strength 0.5 Wet strength 0.5 Ink receptivity 4.5 Blister resistance 4.5 The glass transition temperature of the copolymer latex exceeds the range of the present invention, resulting in poor adhesive strength.

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[Table] (Effects of the Invention) In order to improve the quality and luxury of paper, coated paper is manufactured by coating paper with a paper coating composition containing a pigment as a main component. Important properties of coated paper include water resistance, ink receptivity, adhesive strength, and blister resistance. on the other hand,
Copolymer latexes play an important role as pigment adhesives for coating paper with pigments in coating compositions. However, coating compositions using conventional copolymer latexes cannot achieve a high level of balance among water resistance, ink receptivity, adhesive strength, and blister resistance. The reason for this is that water resistance and ink receptivity have contradictory properties, or adhesive strength and blister resistance have contradictory properties, so it is possible to improve one by improving the copolymer latex. There was a problem that the other property deteriorated. The production of copolymer latex by the method of the present invention is a novel method not previously known, and the obtained copolymer latex has water resistance and ink resistance that could not be obtained with conventional copolymer latex. fleshiness, adhesive strength,
It has a high level of balance in blister resistance, and even when used in binders other than coated paper compositions.
Because it has a high level of physical property balance of adhesive strength, water resistance, and blister resistance, it meets the high quality required by strict production conditions due to expanded binder applications and improved productivity, and has extremely high industrial value. expensive.

Claims (1)

[Claims] 1. 20 to 70% by weight of a conjugated diene monomer, 0.5 to 10% by weight of an ethylenically unsaturated acid monomer, 10 to 50% by weight of an aromatic vinyl monomer, and other copolymerizable materials. In emulsion polymerization of 0 to 69.5% by weight of monomers, (a) monomers corresponding to 20 to 97% by weight of the total monomers are reacted using an organic initiator, and (b) the remaining monomers are then reacted. The monomer is reacted using an inorganic initiator in the presence of the copolymer latex of (a), and the toluene insoluble content of the obtained copolymer latex is 20 to 95% by weight, and the copolymer is A method for producing a copolymer latex, characterized in that the glass transition temperature of the components is 50°C or lower (lower temperature side).