JPH05214287A - Pigment composition - Google Patents

Abstract

PURPOSE:To provide a pigment composition having high performance and good flowability as a binder. CONSTITUTION:A pigment composition which consists mainly of: a copolymer latex produced by using a hydrophilic or water-soluble chain transfer agent together with an oil-soluble chain transfer agent in the emulsion copolymerization of a conjugated diene, an ethylenically unsaturated carboxylic acid and other monomer copolymerizable therewith; and an inorganic pigment composed mainly of calcium carbonate and clay.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pigment composition used for paper coating, carpet backing, and adhesives for various materials.

[0002]

2. Description of the Related Art Conventionally, a pigment composition comprising an inorganic pigment and a synthetic copolymer latex is, for example, a paper coating composition,
It is widely used as a binder for carpet back sizing or as an adhesive for various materials. When the pigment composition is used for such an application, the pigment composition is required to have excellent fluidity, high adhesive strength, water resistance, and blister resistance by dry heating. ..

For example, coated paper has kaolin clay, calcium carbonate, satin white, talc, titanium oxide, etc. on the surface of the raw paper produced for the purpose of improving printability of the paper and optical properties such as gloss. Of the pigment, a copolymer latex as a binder thereof and starch as a water retention agent or an auxiliary binder, polyvinyl alcohol, a pigment composition mainly composed of a water-soluble polymer such as carboxymethyl cellulose. Conventionally, a pigment composition containing a so-called SB latex, which is a styrene-butadiene copolymer latex obtained by emulsion-polymerizing styrene, butadiene, and another monomer, has been widely used.

By the way, in recent years, the production of coated paper has remarkably increased along with the increasing demand for color printed magazines, pamphlets, and advertisements. In particular, with the trend toward high-speed printing in rotary offset printing, the required standard for the quality of coated paper and pigment compositions is also becoming more sophisticated, and in particular, the improvement of surface strength during printing is required. On the other hand, the production of coated paper itself has been accelerated, and there is also a demand for high solidification of pigment composition and improvement of fluidity. The surface strength of the coated paper and the fluidity of the pigment composition, and the solid content and the fluidity often have a negative correlation with each other, and further improvement to achieve a high level balance is required.

Since these properties of the coated paper and the pigment composition are strongly dependent on the design of the SB latex used as the pigment binder, various studies have been made so far on the performance of the SB latex. ..
For example, by increasing the particle size of the latex, the viscosity of the pigment composition at a low shear rate can be reduced. However, according to this method, the viscosity at a high shear rate is increased, and the surface strength of the coated paper is also decreased. The reduction in viscosity by reducing the initiator during the emulsion strong polymerization significantly impairs the stability of the latex and pigment composition. In addition, the amount of unsaturated carboxylic acid monomers used for copolymerization and the amount of acrylic or vinyl ester monomers that form relatively hydrophilic copolymers such as methyl methacrylate, vinyl acetate, etc. The lowering of the viscosity due to the reduction leads to destabilization of the latex and pigment composition, and also lowers the surface strength of the coated paper.

On the other hand, an adhesive for carpet backsizing is generally a pigment composition in which a copolymer latex is mixed with a filler such as calcium carbonate or aluminum hydroxide and other additives such as a thickener. This pigment composition is mainly used for production of tufted carpets, needle punched carpets, etc., for preventing falling off of piles (tashes) and for adhering to secondary base fabric such as jute. Therefore, in this case, the improvement of the adhesive strength, which is the most important physical property of the carpet, and the improvement of the fluidity of the pigment composition at the time of producing the carpet are one of the biggest technical problems in the industry, and therefore, the copolymer latex. Further, improvement studies have been made from the viewpoint of compounding the pigment composition, but the fact is that a satisfactory level has not been obtained so far.

[0007]

As described above, the prior art cannot cope with higher speed printing of coated paper, and a pigment composition which enables the production of high-quality coated paper. The current situation is that there is a strong demand for their appearance. Further, in carpets and adhesives as well, the appearance of a pigment composition having a high adhesive force and good fluidity is desired.

[0008]

Under the circumstances, the present invention further improves the balance between the adhesive strength of coated paper for printing and the fluidity of the pigment composition, or the carpet and the adhesive. As a result of various investigations for the purpose of providing a high-performance pigment composition for improving the adhesive strength of the agent and the fluidity of the pigment composition, use of a specific chain transfer agent in combination during emulsion copolymerization A pigment composition comprising the copolymer latex obtained by and an inorganic pigment having calcium carbonate and / or clay as a main component,
Surprisingly, it was made by discovering that the above purpose was achieved.

That is, the present invention provides a hydrophilic or water-soluble chain transfer agent and an oil-soluble chain transfer agent in emulsion copolymerization of a conjugated diene, an ethylenically unsaturated carboxylic acid and other monomers copolymerizable therewith. A pigment composition comprising a copolymer latex produced in combination with an inorganic pigment containing calcium carbonate and / or clay as a main component.

The present invention will be described in detail below. It is essential that the inorganic pigment in the present invention contains calcium carbonate and / or clay as the main components. Here, the main component means occupying 60% or more of the total volume fraction of the inorganic pigment.
If it is less than 60%, the effect of the present invention is not sufficiently exhibited. Further, as other inorganic pigments, aluminum hydroxide, titanium oxide, satin white, talc, activated clay, etc. may be used if necessary, less than 40% in the total inorganic pigment volume fraction. The combined use of plastic pigments such as polystyrene particles in addition to the inorganic pigments is also a preferred embodiment of the present invention.

The latex polymer in the present invention is a monomer mixture composed of a conjugated diene (a), an ethylenically unsaturated carboxylic acid (b), and another monomer (c) copolymerizable therewith. It can be obtained by using a specific chain transfer agent together when emulsion-copolymerizing the liquid. Examples of the conjugated diene (a) include butadiene, isoprene, 2-chloro-1,3-butadiene and the like. The amount used is preferably in the range of 20 to 90% by weight based on the total monomers. Further, in the case of a copolymer latex for coated paper, a more preferable amount range of this conjugated diene is 20 to 70% by weight.

The ethylenically unsaturated carboxylic acid (b) is 0.
It is preferably in the range of 5 to 10% by weight. If it is less than 0.5% by weight, the dispersion stability of the latex cannot be maintained at a high level, and various problems will occur during coating preparation and coating. Also, the pick strength is poor. If it is contained in an amount of more than 10% by weight, the viscosity of the latex or pigment composition will be too high and the water resistance will be impaired. Examples of the ethylenically unsaturated carboxylic acid include monobasic carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, dibasic carboxylic acids such as itaconic acid, maleic acid and fumaric acid, and monoesters thereof. You can Among these, dibasic carboxylic acids are preferable because they exhibit the effects of the present invention most effectively.

Among the other examples of the monomer (c), the most representative and effective one is the aromatic (di) vinyl compound, followed by (meth) acrylic acid ester, vinyl cyanide compound and ethylene. Amide monomer and the like. Aromatic (di) vinyl compounds include styrene and α
-Methylstyrene, chlorostyrene, alkylstyrene, divinylbenzene and the like.

Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, hydroxyethyl (meth) acrylate. Moreover,
Examples thereof include glycidyl (meth) acrylate and ethylene glycol di (meth) acrylate.

Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile. Examples of the ethylenic amide monomer include (meth) acrylamide and N-methylol (meth) acrylamide. In addition, vinyl ester such as vinyl acetate,
Examples thereof include vinyl halides such as vinyl chloride and vinylidene chloride, ethylenic amine monomers such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, sodium styrenesulfonate, and the like. ..

The hydrophilic or water-soluble chain transfer agent used in the present invention is not particularly limited as long as it can control the molecular weight when the monomer dissolved in the aqueous phase is polymerized during the polymerization of latex. It is not something that will be done. Hydrophilic or water-soluble chain transfer agents are distinguished from other chain transfer agents by the range of chain transfer constants and water solubility that they simultaneously satisfy.

The chain transfer constant of the hydrophilic or water-soluble chain transfer agent used in the present invention varies depending on the type of monomers used for polymerization, the polymerization temperature, etc., but the effect as a chain transfer agent is greater than a certain extent. Therefore, the chain transfer constant is 5 × 10 ⁻⁶ or more, preferably 1 × 10 ⁻⁴ or more, more preferably 1 ×, in the vicinity of the temperature at which polymerization actually occurs.
It is 10 ^-3 or more.

As the hydrophilic or water-soluble chain transfer agent,
A compound containing at least one element that activates a chain transfer reaction such as halogen, sulfur and phosphorus in the molecule, and at the same time, usually a carboxyl group, a hydroxyl group, a sulfate group to impart hydrophilicity or water solubility, Examples include reducing compounds having a sulfonic acid group and an amide group. For example, bromoacetic acid, chloroacetic acid, thioglycolic acid, L-cystine,
Examples include β-thiodiglycol, cysteamine and hypophosphite alkali salts. The amount of the hydrophilic or water-soluble chain transfer agent used depends on the size of its chain transfer constant.
Even 0.05 parts by weight with respect to parts by weight of the monomer has a sufficient effect of lowering the viscosity of the latex and the pigment dispersion pair. Usually, it is used in the range of 0.05 to 10 parts by weight with respect to 100 parts by weight of the monomer.

The hydrophilic or water-soluble chain transfer agent may be added continuously or discontinuously in at least one step of emulsion polymerization, but it is of course considered that the effect varies depending on which step is added. Be done. The emulsion polymerization includes batch polymerization method, semi-batch polymerization method, continuous polymerization method and the like. In these polymerization methods, the hydrophilic or water-soluble chain transfer agent can be added at any step and at any time.

When the hydrophilic or water-soluble chain transfer agent used in the present invention is used in combination with an oil-soluble chain transfer agent, the oil-soluble chain transfer agent may be a compound containing a sulfur element, a halogenated hydrocarbon or an α-alkyl group. Styrene dimer, diphenylethylene and its nucleus-substituted compounds, enol ether,
Examples include naphthalene derivatives, azobenzene derivatives, terpinolene, dipentene and t-terpinene. Examples of chain transfer agents containing elemental sulfur include alkanethiols such as t-dodecyl mercaptan and n-dodecyl mercaptan: thioalkyl alcohols such as mercaptoethanol and mercaptopropanol: thioalkylcarboxylic acids such as thioglycolic acid and thiopropionic acid: Examples include thiocarboxylic acid alkyl esters such as thioglycolic acid octyl ester and thiopropionic acid octyl ester: sulfides such as dimethyl sulfide and diethyl sulfide. A preferable example of the chain transfer agent containing the elemental sulfur is thioalkylcarboxylic acid alkyl ester.

Examples of halogenated hydrocarbons are carbon tetrachloride and chloroform, examples of naphthalene derivatives are naphthol and methoxynaphthalene, and examples of azobenzene derivatives are azobenzene and hydroxyazobenzene. As for these oil-soluble chain transfer agents, it is naturally possible to use not only each of them but also a mixture thereof.

The amount of the oil-soluble chain transfer agent used is set so as to satisfy the practical physical properties in the final use, but it is usually in the range of 0.05 to 15 parts by weight with respect to 100 parts by weight of the monomer. Is selected in. In the present invention, various methods can be used for adding the oil-soluble chain transfer agent. That is, a batch addition method, a continuous addition method, a continuous addition method with a gradient in the addition rate, and the like. In addition, a method of previously adding a part of the oil-soluble chain transfer agent to the monomer mixture, terminating the addition of the mixture during the polymerization, and continuously adding the remaining oil-soluble chain transfer agent alone is also possible. This is the preferred method.

Next, a method for producing a copolymer latex will be described. The copolymer latex of the present invention contains water, a surfactant,
In a dispersion system containing a monomer, a radical polymerization initiator and, if necessary, other raw materials as basic constituents, these raw materials can be obtained as an aqueous dispersion of copolymer particles by radical emulsion polymerization. Generally, the copolymer concentration is 40-60.
It is in the range of% by weight.

The particle size of the copolymer latex can be adjusted by the use ratio of the surfactant and / or seed latex, and the particle size of the produced copolymer latex decreases as the use ratio increases. Here, the particle size is preferably in the range of 0.05 to 1 μm, and more preferably 0.07 to 0.5 μm. Examples of the surfactant include anionic surfactants such as fatty acid soap, rosin acid soap, alkyl sulfonate, dialkylaryl sulfonate, alkylsulfosuccinate, polyoxyethylene alkyl sulfate, and polyoxyethylene alkylaryl sulfate. , Polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene sorbitan fatty acid ester, oxyethylene oxypropylene block copolymer, and other nonionic surfactants, and cationic surfactants. Other examples of these surfactants include "Surfactant Handbook (Takahashi, Namba, Koike, Kobayashi: Engineering Books, 1
972) ”and the like. The surfactant is usually used as an anionic surfactant alone or in an anionic / nonionic mixed system, and the ratio of the surfactant to the monomer is preferably 0.05 to 2% by weight.

The polymerization initiator is a compound that radically decomposes in the presence of heat or a reducing substance to initiate addition polymerization of a monomer, and is generally a peroxodisulfate, a peroxide, an azobis compound or the like. Used for. Specific examples thereof include potassium peroxodisulfate, sodium peroxodisulfate, ammonium peroxodisulfate, hydrogen peroxide, and t.
-Butyl hydroperoxide, benzoyl peroxide,
There are 2,2-azobisisobutyronitrile, cumene hydroperoxide and the like, and other examples include the compounds described in “Revised Polymer Synthesis Chemistry (Otsu: Kagaku Dojin, 1979)”. Of these, peroxodisulfate is particularly preferred because it exhibits the effects of the present invention well. The amount of the polymerization initiator used is 0.
It is preferably from 2 to 2.0% by weight. The polymerization temperature is generally in the range of 60 to 90 ° C., but when acceleration of the polymerization rate or polymerization at a lower temperature is desired, sodium bisulfite, ascorbic acid or its salt, erythorbic acid or its salt, Rongalit, etc. The so-called redox polymerization method in which the reducing agent of (1) is used in combination with the polymerization initiator can be used.

Further, if desired, various polymerization regulators are often added. Examples thereof include pH adjusting agents such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium hydrogen carbonate, sodium carbonate and disodium hydrogen phosphate, and various chelating agents such as sodium ethylenediaminetetraacetate. The inorganic pigment composition of the present invention can be prepared in a usual manner. That is, it is a mode in which a copolymer latex is mixed with an inorganic pigment and / or an organic pigment, a water-soluble polymer, and various additives in water in which a dispersant is dissolved to form a uniform dispersion liquid. Specific examples of each raw material of these inorganic pigment aqueous dispersions include those described in "Handbook of Paper Processing (edited by Paper Industry Times: Paper Industry Times, 1980)". This inorganic pigment composition can be applied to a base paper by a known method such as various blade coaters and roll coaters to produce a coated paper, and can be used as an adhesive for carpet backing or an adhesive for various materials. it can. The coated paper can be subjected to various kinds of printing such as gravure, sheet-fed offset, and rotary offset, and of these, the coated paperboard can be subjected to various packaging.

[0027]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0028]

[Examples and Comparative Examples]

Preparation of copolymer latex: A proper amount of an aqueous dispersion of seed particles having a diameter of 0.038 μm (seed solid content concentration 30% by weight) was put in a pressure resistant reaction vessel equipped with a stirring device and a temperature control jacket, and further 70% of water was added. Parts, 0.2 parts by weight of sodium lauryl sulfate, a hydrophilic or water-soluble chain transfer agent, itaconic acid and / or fumaric acid were charged, the internal temperature was kept at 80 ° C., and then 15 parts by weight of water, sodium peroxodisulfate and hydroxylation were added. An aqueous solution containing sodium and sodium dodecylbenzene sulfonate was added from time 0 to 5
The monomer mixture was added over a period of time from 0 to 4 hours. Then, the temperature of 80 ° C. was kept as it was for 2 hours and then cooled, and then the produced copolymer latex was adjusted to pH 8 with potassium hydroxide in an amount shown in Tables 1 and 2 and an appropriate amount of sodium hydroxide, Unreacted and volatile monomers were removed by the steam stripping method, and the mixture was filtered with a filter cloth having a mesh of 75 μm. In addition, all the copolymer latexes were adjusted so that the final solid content was 50% by weight. As Comparative Example 2, a latex prepared by adding 0.5 parts by weight of sodium hexametaphosphate to the latex polymerized in Comparative Example 1 was prepared.

Details of the raw materials and the amounts (parts by weight) of these copolymer latexes are shown in Tables 1, 2, 3 and 4.
(Comparative examples do not use hydrophilic or water-soluble chain transfer agents)

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

Each characteristic was obtained as follows. (A) Average particle size Light scattering particle size analyzer (Model 600 manufactured by CN Wood Co., Ltd.)
The average particle size of the copolymer latex was measured according to 0). (B) Conversion rate Styrene was selected as a representative of the monomers that are polymerization raw materials, and the conversion was calculated from the ratio of the residual amount and the charged amount. The residual amount was quantified by a known method by gas chromatography.

[0035]

[Examples 1 to 12 and Comparative Examples 1 to 6] Performance evaluation as a coating liquid for paper coating; Pigment compositions of Examples 1 to 12 and Comparative Examples 1 to 6 of the copolymer latex prepared above The performance as a coating liquid for paper coating was evaluated. The pigment composition was prepared according to the formulation shown in Table 5 using a high-speed agitator with an amount of water such that the concentration of nonvolatile components was 63% by weight. Table 6 shows the conditions for preparing coated paper using this pigment composition.

The performance of the coated paper was evaluated separately as in Examples 1 to 12 and Comparative Examples 1 to 6 in Tables 7, 8 and 9. The results are shown in Tables 7, 8 and 9. From Tables 7, 8 and 9, it is understood that when the pigment composition of the present invention is used as the coating liquid, the balance between the viscosity of the coating liquid and the physical properties of the coated paper is highly excellent.

[0037]

[Table 5]

[0038]

[Table 6]

[0039]

[Table 7]

[0040]

[Table 8]

[0041]

[Table 9]

The properties of the pigment composition and coated paper were determined as follows. (C) Pigment composition viscosity (low share) It was measured using a BL type viscometer (60 rpm, No. 4 spindle). (D) Pigment composition viscosity (high share) It was measured using a Hercules viscometer (8800 rpm, E Bob).

(E) White paper gloss gloss meter (manufactured by Murakami Color Research Laboratory), 75 °-
The reflectance at 75 ° was obtained. (F) Printing Gloss Printing ink on both sides of coated paper using an RI printing tester (manufactured by Ming Seisakusho) (WebbZett yellow, manufactured by Dainippon Ink and Chemicals)
Make a solid print of 0.3 cm ³ . After being dried at room temperature for 1 day, the reflectance at 60 ° -60 ° was measured with a gloss meter.

(G) Dry pick strength Using a RI printing tester, printing ink (SD Super Deluxe 50 Hong B; Tack value 15, Toka Dye Co., Ltd.) was used.
Overprinting is performed several times at 4 cm ³ , and the picked state appearing on the rubber roll is lined on another mount, and the degree is observed. The evaluation was carried out by a 10-point evaluation method, and the smaller the picking phenomenon, the higher the score.

(H) Wet Pick Strength Using a RI printing tester, the surface of the coated paper was moistened with a relatively small amount of water using a molton roll, and then the printing ink (SD
Super Deluxe 50 Red B; Tack value 15, manufactured by Toka Dye Co., Ltd.) 0.4 cm ^{3 is} printed once, the picked state appearing on the rubber roll is lined on another mount, and the degree is observed. The evaluation was carried out by a 10-point evaluation method, and the smaller the picking phenomenon, the higher the score.

(I) Wet Inking The coated paper surface was moistened with a relatively large amount of water using a Molton roll using an RI printing tester, and then the printing ink (We
bb Zett yellow, manufactured by Dainippon Ink and Chemicals, Inc.) 0.3 cm ³ is solidly printed and the transferability of the ink is observed. Evaluation is 10
The higher the ink transfer, the higher the score.

(N) Ink set 0.4c of printing ink (Webb Zett Yellow, manufactured by Dainippon Ink and Chemicals, Inc.) on the surface of coated paper using an RI printing tester
Make a solid print of m ³ and observe the dry state of the ink. The evaluation was performed by a 10-point evaluation method, and the better the ink drying, the higher the score.

[0048]

Examples 13-14 and Comparative Examples 7-8 Performance evaluation as a binder for carpet backsizing; Example 13 of the copolymer latex prepared above
-14 and the pigment compositions of Comparative Examples 7 to 8 were evaluated for performance as a binder for carpet backsizing. The pigment composition was prepared according to the formulation shown in Table 10 using a high-speed agitator with an amount of water such that the concentration of nonvolatile components was 70% by weight. Table 11 shows the conditions for carpet backsizing using this pigment composition.

The physical properties (viscosity) of the pigment composition are shown in Examples 1-12.
And the conditions shown in (c) of Comparative Examples 1 to 6 (however, 4 rpm)
Further, the carpet back sizing performance (peeling strength and yarn removal strength) was determined in accordance with JIS L-1021.
The higher the average value, the better. The results are shown in Table 12.
From Table 12, it can be seen that the carpet using the pigment composition of the present invention as the binder has the peel strength and the yarn removal strength highly improved.

[0050]

[Table 10]

[0051]

[Table 11]

[0052]

[Table 12]

[0053]

According to the present invention, the balance between the viscosity of the pigment dispersion in the printing coated paper and the other properties of the coated paper is improved, or the viscosity and adhesive strength in the carpet back sizing and the adhesive are improved. It is possible to easily obtain a high-performance pigment composition that can be improved.

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Claims (1)

[Claims] 1. A hydrophilic or water-soluble chain transfer agent and an oil-soluble chain transfer agent are used in combination in emulsion copolymerization of a conjugated diene, an ethylenically unsaturated carboxylic acid and other monomers copolymerizable therewith. A pigment composition comprising, as a main component, a copolymer latex produced by the method and an inorganic pigment containing calcium carbonate and / or clay as a main component.