JPH05331797A - Polymer composition useful as binder for colorant for coating and colorant for coating manufactured thereof - Google Patents

Abstract

PURPOSE: To obtain a polymer composition effectively usable as a coating colorant for imparting a coated paper with excellent balance. CONSTITUTION: This polymer composition is characterized by comprising a binder copolymer derived from an α,β-ethylenically unsaturated carboxylic ester, a water-soluble homopolymer-forming comonomer and optionally another comonomer, and a lightly crosslinked, water-dispersible, rheology-controllable copolymer made from an α,β-ethylenically unsaturated carboxylic acid, an α,β- ethylenically unsaturated carboxylic ester, an ethylenically unsaturated carboxamide, a crosslinkable monomer and optionally at least one copolymerizable monomer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to synthetic polymer compositions useful as binder components in coating colorants and coating colorants containing these polymer compositions.

In the manufacture of paper, the surface of the paper is often coated with a composition that provides the paper with desirable properties such as printability, commonly referred to as a coating colorant. In one conventional method for applying a coating colorant, the coating is continuously transferred as a liquid film from a coating roller to the surface of the paper, with the excess applied being applied by blade or air knife techniques. Removed using suitable equipment.

For various reasons, papermakers have continually made efforts to reduce the final weight of coated papers. One way to achieve this is to reduce the amount of coating colorant applied to the paper. Unfortunately, reduced coat weight generally results in poor properties of the final paper, especially poor print quality. In order to effectively coat the paper at the desired coat weight, the coating colorant advantageously exhibits desirable physical properties such as stability and rheology. These properties are especially important in the production of high quality paper, for example those printed by gravure technology.

[0004]

Conventionally, coating colorants consist primarily of suspensions of pigments and / or fillers such as clay in an aqueous medium containing a binder. Traditionally, natural high molecular weight substances such as starch or proteins have been used as binders. Unfortunately, these natural materials are susceptible to microbial attack and, when used alone, give a brittle coating. Moreover, with the use of starch binders, the coated papers often do not have the required print quality due to insufficient coating resistance, ie excessive penetration of the coating into the paper.

It has therefore been proposed to use synthetic polymers as binders for paper coatings. Many such synthetic polymeric binders consist of two polymeric components, where the first copolymer is primarily used to impart the desired binder strength and other properties, and the second copolymer is It is primarily used to influence the rheological properties of coating colorants made therefrom. For example, in West German Patent 1,546,315, 60-95% of a first copolymer of butadiene, styrene and / or acrylonitrile and acrylic acid or methacrylic acid, a monomer that produces a water insoluble homopolymer (at least some of which is A synthetic polymer binder consisting of 5 to 40% of a second copolymer of acrylic or methacrylic-amide, which is an ester of acrylic or methacrylic acid), and as an optional component. Unfortunately, the properties of coating colorants coated papers made from this binder are again deficient in general due to poor coating resistance, especially when using gravure printing techniques.

A similar synthetic polymeric binder except that the first copolymer was derived from an ester of acrylic or methacrylic acid, a vinyl ester or propionic acid, and optionally other copolymerizable monomers is described in US Pat. , 365,410. Although coating colorants made using these polymeric binders improve the printability of papers made therefrom, there is a need for further improvement in the balance of paper properties.

[0007]

In view of the above deficiencies of previously used synthetic polymeric binders, they have been used effectively as paper coating colorants to impart an improved balance of properties of the coated paper. It is still highly desirable to provide a possible polymer composition.

[0008]

SUMMARY OF THE INVENTION The present invention, therefore, relates to such improved polymer compositions useful as binder components in coating colorants. This polymer composition consists of two polymer components, the improvement of which is one component of these two components: an α, β-ethylenically unsaturated carboxylic acid ester and an α, β-ethylenically unsaturated carboxylic acid ester. from a lightly cross-linked copolymer comprising a β-ethylenically unsaturated carboxylic acid, an unsaturated carboxamide, and optionally one or more other comonomers in polymerized form. Become. This lightly cross-linked copolymer (hereinafter referred to as the "rheology control copolymer") is sufficient to improve the rheological and / or other properties of the polymer composition and / or coating colorant prepared therefrom. Are cross-coupled to.

Such cross-linking in the copolymer is achieved by using a small amount (ie 0.01-10% by weight) of the cross-linking monomer. The other copolymer (hereinafter referred to as "binder copolymer") comprises an ester of an α, β-ethylenically unsaturated carboxylic acid, a comonomer forming a water-insoluble homopolymer, and optionally one or more It is a copolymer with a copolymerizable monomer.

Coating colorants containing fully cross-linked polymeric components have rheological and / or other properties not obtainable without the cross-linked components. Moreover, the flexibility afforded by the cross-linked structure allows for easy adaptability of the polymeric binder composition to various formulations in the manufacture of coating colorants. Paper coated with this coating colorant exhibits unexpectedly high flexural strength and excellent printability.

The polymer composition of the present invention is useful as a binder component in various compositions, especially coating colorants. They are particularly useful for the production of coating colorants used in the production of high-quality printing papers, for example in the production of rotogravure printing.

The polymer composition of the present invention comprises two polymer components, namely the binder copolymer and the two polymer components referred to herein as the rheology control polymer.

The binder copolymer is derived from an ester of an α, β-ethylenically unsaturated carboxylic acid and a water insoluble homopolymer forming comonomer. Representative esters are esters of acrylic acid and / or methacrylic acid with alcohols of 1 to 8 carbon atoms such as ethyl acrylate, n-butyl acrylate, i-butyl acrylate, 2-ethylhexyl acrylate and the like. Esters of acrylic acid with alcohols of 4 to 8 carbon atoms are preferred. Typical comonomers which form water-insoluble homopolymers are generally monovinylidene aromatics, especially styrene; unsaturated nitriles, especially acrylonitrile; vinyl esters of monocarboxylic acids, especially vinyl acetate or vinyl propionate; haloolefins such as vinyl chloride or vinylidene chloride; Alternatively, a combination thereof is included. Preferred of these comonomers are vinyl esters, especially vinyl acetate and vinyl propionate. Generally, the binder copolymer comprises 10 to 90% by weight, preferably 35 to 60% by weight of an ester of an unsaturated carboxylic acid and 10 to 90% by weight, preferably 35 to 60% by weight of vinyl acetate, based on the total weight of the binder copolymer. And optionally up to 10% by weight of further comonomers. Such further comonomers may be comonomers which form water-insoluble homopolymers, but more advantageously α, β-ethylenically unsaturated carboxylic acids, preferably acids of 3 to 5 carbon atoms, such as acrylic acid, Methacrylic acid, crotonic acid, maleic acid, fumaric acid, or itaconic acid and their amides, monoalkylamides, dialkylamides, N-methyllolamides and esters of said N-methylolamides (half-amides and half-esters of dicarboxylic acids) Also included); or more strongly comonomers such as vinyl sulfonic acid and p-toluene sulfonic acid. Preferred among such comonomers are α, β-ethylenically unsaturated acids, especially those acids having 3 to 5 carbon atoms.
These acids are preferably used in amounts of 0.1 to 5% by weight, based on the total weight of the binder copolymer.

The rheology control polymer component comprises an α, β-ethylenically unsaturated acid, an ester of an α, β-ethylenically unsaturated carboxylic acid, an unsaturated carboxamide, and optionally one or more other Consisting of a lightly cross-linked copolymer with the comonomers of.

Α, β-, which is advantageously used in the present invention
Esters of ethylenically unsaturated acids include carboxylic acids having 3 to 5 carbon atoms such as acrylic acid, methacrylic acid,
Esters of maleic acid, fumaric acid or itaconic acid (preferably acrylic acid or methacrylic acid) with alcohols having 2 to 10, preferably 2 to 4 carbon atoms. An example of such an ester is ethyl acrylate,
Examples thereof include propyl acrylate, butyl acrylate, propyl methacrylate and butyl acrylate. The unsaturated carboxylic acids preferably used in the present invention are carboxylic acids having 3 to 10 carbon atoms. Typical of such acids are acrylic acid, methacrylic acid, crotonic acid,
Itaconic acid, fumaric acid and ethyl acrylic acid.

Typical ethylenically unsaturated carboxamides include acrylamide, methacrylamide, crotonamide, itaconamide, maleic acid monoamide, and ethyl acrylamide.

Generally, the rheology control polymer is lightly cross-linked using cross-linking monomers, ie, copolymerizable monomers that when incorporated into the polymerization formulation, introduce cross-links into the resulting polymer. Representative cross-linking monomers include ethylenically unsaturated monomers containing two or more non-conjugated terminal ethylenic groups. Examples of such monomers are polyvinylidene aromatics such as divinylbenzene, divinyltoluene, divinylxylene and trivinylbenzene; allyl- or butenyl acrylates and / or methacrylates such as allyl methacrylate, ethylene glycol dimethyl acrylate. .. Preferred cross-linking monomers are those containing from 4 to 15 carbon atoms, with allyl acrylate and allyl methacrylate being most preferred.

The particular monomer components, including the cross-linking monomers and their amounts, which are most advantageously used to produce the rheology control polymer, and the relative proportions of each, are related to the composition of the coating colorant produced therefrom. It depends on various factors involved. For example, when the binder copolymer is a copolymer of an ester of an unsaturated acid and a vinyl ester of an unsaturated carboxylic acid, the desired polymer properties of these copolymers are often an ester of the unsaturated carboxylic acid, preferably 40-90. Ester of weight% acrylic acid with alcohol of 1 to 8 carbon atoms; unsaturated acid carboxylic acid, preferably 5 to 40% by weight of acrylic acid and / or methacrylic acid; and unsaturated carboxamide, preferably 0.5. 10% by weight of acrylamide and / or methacrylamide (these% by weight
Is obtained using a lightly cross-linked polymer derived from (based on the total weight of the rheology control polymer). The crosslinks are advantageously introduced using 0.05 to 5% by weight of crosslinkable monomers, preferably 0.05 to 2% by weight of allyl acrylate or methacrylate. Also, small amount (ie less than 10% by weight)
Other comonomers such as unsaturated nitriles, monovinylidene aromatics, monocarboxylic acid vinyl esters can optionally be used.

The binder copolymer and the rheology control copolymer are prepared separately using continuous, semi-continuous or batch emulsion polymerization techniques. Such techniques are well known in the art and are cited for the purposes of the present invention. Generally, these polymer components are emulsifiers and other commonly used polymerization aids such as chain transfer agents,
It is prepared by dispersing the desired monomers in an aqueous medium that typically contains a chelating agent.

Free-radical initiating means which are preferably used are UV and conventional chemical initiators such as hydrogen peroxide and quinene hydroperoxide; persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate;
Organic azo compounds such as azobisisobutyronitrile;
Redox initiators such as peroxide in combination with sulfite or thiosulfite reducing agents; and the like are included. Typically, such initiators are generally used in amounts ranging from 0.01 to 5% by weight, based on the total weight of monomers to be polymerized.

Surfactants which are advantageously used in the preparation of the copolymers are the anionic and nonionic surfactants which are customary in the emulsion polymerization. Representative anionic surfactants useful herein include alkylaryl sulfonates such as sodium dodecylbenzene sulfonate, alkylphenoxy polyethylene sulfonates and phosphates, sodium lauryl sulphate, potassium lauryl sulphonate and the like. Representative nonionic surfactants useful herein include the reaction formation of alkylene oxides with alkylated phenols or long chain fatty alcohols, fatty acids, alkyl mercaptans, eg 6 to 20 carbon atoms, with primary amines, monoesters. Products such as reaction products of polyethylene glycol, long chain carboxylic acids and polyglycol esters of polyhydric alcohols. The surfactant is used in an amount that effectively stabilizes the dispersion during polymerization. In general,
Such amounts range from 0.1 to 5% by weight, based on the total weight of monomers used. A chain transfer agent is often, but optionally, included in the aqueous medium to help control the molecular weight of the resulting polymer. Generally, chain transfer agents conventionally conveniently used in emulsion polymerization processes can be used in the practice of this invention. Representative of such chain transfer agents include mercaptans such as n-dodecyl mercaptan cyclohexene, bromoform, carbon tetrabromide, carbon tetrachloride and the like. When used, the chain transfer agent generally ranges from 0.05 to 0.05 based on the total weight of the monomers.
It is advantageously used in an amount of 5% by weight.

The polymerization is advantageously carried out at temperatures low enough to polymerize the monomers at a practical rate. Generally, the polymerization is conducted at a temperature of 40 to 100 ° C, preferably 60 to 90 ° C, for a time sufficient to convert the desired amount of monomer to the desired polymer (generally at least 90% of the monomer converted to polymer), usually 1 to It will be held for 6 hours. The polymer dispersions can be prepared over a wide range of concentrations, but preferably the resulting aqueous dispersions have a solids content in the range 20-60% by weight.

The polymer product of the present invention is prepared by mixing the desired amount of binder copolymer with the rheology control copolymer. The relative concentrations of binder copolymer and rheology control copolymer are chosen based on the desired properties of the polymer composition and coating colorants made therefrom. Generally, the binder copolymer is used in an amount of 50 to 97% by weight, preferably 60 to 90% by weight, more preferably 70 to 90% by weight, the rheology control copolymer is 3 to 50% by weight, preferably 10 to 40% by weight. , And more preferably 10
Used in an amount of up to 30% by weight, but these weight%
Is based on the total weight of the two copolymers.

The method of mixing the two polymers is not particularly critical to the practice of the present invention. In general, the dispersions of the two polymers are compatible with each other, especially when the carboxyl of either or both copolymers is not neutralized or only partially neutralized prior to mixing. is there. Mixing of the two polymer dispersions is easily accomplished by mixing the as-produced dispersion of the first binder copolymer with the as-produced dispersion of the rheology control copolymer with gentle agitation.

In the preparation of coating colorants using the polymer composition of the present invention as a binder component, the polymer composition of the present invention can be used as a filler and / or a filler including clay and optionally chioke or calcium carbonate. Alternatively, it is usually mixed with other ingredients such as pigments and, if desired, other auxiliaries such as dispersants, lubricants or the like. Although such auxiliaries can be mixed with the comonomers in any way prior to the subsequent mixing of the copolymers, aqueous dispersions of pigments and / or fillers are generally prepared and added to this with stirring just before use. Add copolymers.
Prior to applying the coating colorant comprising the polymer composition of the present invention to the surface of the paper, the carboxyl groups are removed by adding a basic substance such as sodium hydroxide or potassium hydroxide or ammonium hydroxide, preferably sodium hydroxide. It is advantageous to neutralize. Sufficient alkali is added to the polymer-containing aqueous dispersion to provide a pH of 8-9.5. The resulting coating colorant can be applied to the raw paper using any of the well known methods.

The following examples serve to illustrate the invention and should not be construed as limiting its scope. In these examples all parts and percentages are by weight unless otherwise stated.

[0027]

【Example】

Preparation of Binder Copolymer In a suitable size polymerization flask equipped with stirrer, heating and cooling device, thermometer and addition funnel, 60 parts water,
0.1 part anionic surfactant, 0.8 part free radical initiator, and 3 parts chain transfer agent were added. The vessel was purged with nitrogen and heated to 90 ° C. Over 4 hours, 50 parts butyl acrylate, 47 parts vinyl acetate and 3 parts acrylic acid were added in cocurrent with an aqueous stream containing additional surfactant and free radical initiator. The vessel was held at 90 ° C during the addition and for a further 2 hours thereafter. At this point the polymerization was stopped. The resulting emulsion contained 50% solids and the resulting butyl acrylate / vinyl acetate / acrylic acid copolymer particle size was about 18
It turned out to be 00Å.

Preparation of Rheology Control Polymer 148 parts water, 0.02 parts chelating agent and 0.5 parts anionic surface in a polymerization vessel of suitable size similar to that used to prepare the first copolymer. Activator was added. The vessel was then heated to 80 ° C. A first monomer feed stream consisting of 75 parts ethyl acrylate, 20 parts acrylic acid and 0.1 part allyl methacrylate was added to the above gently stirred aqueous polymerization mixture over a period of about 4 hours. A second additional monomer additive consisting of a solution of 40 parts water, 5 parts acrylamide and 0.005 parts chelating agent was simultaneously added to the reaction vessel. However, the addition started about 15 minutes after the first monomer stream. Upon addition of these monomers, an additional 50 parts water, 2.0 parts anionic surfactant, 0.1 parts sodium hydroxide and 0.7 parts free radical initiator are added to the polymerization medium. added. The temperature of the vessel was maintained at 80 ° C during the addition of the monomers and the polymerization aid and for a further 2 hours thereafter. At the end of this period, the flask was then cooled to room temperature and the emulsion subsequently subjected to steam distillation to remove unconverted monomers. Generated emulsion is about 30
% Solids.

Preparation of coating colorant 70 parts of binder copolymer-containing emulsion on a dry basis are mixed with 30 parts of a rheology control copolymer-containing emulsion on a dry basis with gentle agitation to form a 44% by weight solids blend. To produce a polymer blend.

Using vigorous stirring, adding 5 parts of the above blend to 100 parts of Dinkie A clay dispersed in an aqueous solution of 0.1 part of sodium polyacrylate and 0.2 part of sodium metaphosphate. To produce a paper coating composition. PH of the resulting mixture
Was then adjusted to 8.5 by adding caustic soda.
The resulting paper coating (Sample No. 1) contained 56% solids and was produced by Brukfield Viscometer Type No. RVT
Spindle N at 100 rpm and 25 ° C
o. 5 had a viscosity of 2150 cps.

In a similar manner, a paper coating (Sample No. 2) was prepared by blending 75 parts (dry basis) of the emulsion containing the binder copolymer with 25 parts (dry basis) of the emulsion containing the rheology control copolymer. .. The paper coating was found to contain about 56% solids and has a viscosity of 2500 cps.

Each of these paper coatings was subjected to a speed of 600 m / min and 10 using conventional blade coating techniques.
In coating weight g / ^{m 2,} it was coated separately on a substrate paper of 36 g / ^{m 2} with 6 percent moisture. Excellent operating characteristics were observed. The bond strength and printability of the coated paper was measured.
The results of these measurements are shown in Table 1.

For comparison, Table 1 also shows the bond strength and printability exhibited by the two coating colorants prepared using the polymeric binders described in the prior art (Sample No. 5). A and B).

[0034]

[Table 1]

Note: (1) Polymer binder: Each component of the polymer binder is represented by the following abbreviations. BA = butyl acrylate,
VA = vinyl acetate, AA = acrylic acid, EA = ethyl acrylate, AAm = acrylamide, AM = acrylic methacrylate. The weight% means the weight% of each monomer in the specific component based on the total weight of the polymer component. %
CB: RCP refers to the weight% of the binder copolymer and the rheology control polymer in the production of the polymer composition.

(2) First of acrylate and vinyl acetate
A typical acrylic polymer binder consisting of a copolymer and a second copolymer of acrylate, carboxylic acid and amide.

(3) Derived from 57 parts styrene / 39 parts butadiene / 1 part itaconic acid / 3 parts acrylic acid and 70 parts ethyl acrylate, 20 parts methacrylic acid and 10 parts acrylamide. A polymeric binder comprising a second copolymer.

(4) Viscosity was measured using a Brookfield viscometer model RVT using a spindle No. 5 using 10
Measured at 0 rpm and 20 ° C.

(5) The bond strength was measured using a conventional IGT tester equipped with a pendulum driver. Results are reported in units of cm / sec to the first tip of the coated paper using a low viscosity oil with a printing pressure of 350 Newton / cm ² .

(6) The printability was measured using a test device for measuring the printability of the paper printed using the rotary gravure printing technique adapted to the pendulum drive IGI tester 2A type. Results are reported in mm for 20 ambiguities using a printing pressure of 250 Newton / cm ² .

As is clear from the data shown in Table 1,
The polymer composition of the present invention is an unusual binder for paper coating. In particular, paper coatings made using the polymer compositions of the present invention impart unexpectedly high flexural strength in combination with excellent printing properties.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C08L 33/24 LJV 7921-4J C09C 3/10 PBZ 6904-4J C09D 131/02 PFU 6904-4J 133 / 08 PFY 7921-4J D21H 19/44 (72) Inventor Bernardus Maria Serafinez van Luden Switzerland 8810 Hogen Gustaldens Trasse 3

Claims (4)

[Claims] 1. A binder copolymer derived from an α, β-ethylenically unsaturated carboxylic acid ester, a comonomer forming a water-insoluble homopolymer, and optionally other comonomers, and an α, β-ethylenically unsaturated A carboxylic acid, an α, β-ethylenically unsaturated carboxylic acid ester,
A lightly cross-linked aqueous dispersion rheology control copolymer of an ethylenically unsaturated carboxamide, a cross-linking monomer, and optionally one or more copolymerizable monomers, the cross-linking monomer being a rheology control copolymer. 0.01-1 based on weight
A polymer composition for use as a binder component of a coating colorant, characterized in that it comprises 0% by weight. 2. The binder copolymer comprises 35-60% by weight of an ester of acrylic acid and / or methacrylic acid with a C _1-8 alcohol, 35-60% by weight of vinyl acetate and / or vinyl propionate, and 10% by weight. % Copolymerizable monomer, but these weight percentages are derived from the total weight of the binder copolymer,
The rheology control copolymer is 40 to 90% by weight of an ester of acrylic acid and a C _1-8 alcohol.
And acrylic acid and / or methacrylic acid 0.5 to 10
% By weight, up to 10% by weight of other copolymerizable monomers, 0.05 to 5% by weight of cross-linking monomers, provided that these% by weight are based on the total weight of the rheology control copolymer. The polymer composition according to claim 1. 3. A binder copolymer derived from an α, β-ethylenically unsaturated carboxylic acid ester, a comonomer forming a water-insoluble homopolymer, and optionally other comonomers, and an α, β-ethylenically unsaturated A carboxylic acid, an α, β-ethylenically unsaturated carboxylic acid ester,
A lightly cross-linked aqueous dispersion rheology control copolymer of an ethylenically unsaturated carboxamide, a cross-linking monomer, and optionally one or more copolymerizable monomers, the cross-linking monomer being a rheology control copolymer. 0.01-1 based on weight
A colorant for paper coatings, characterized in that it comprises a polymer composition containing 0% by weight as binder component and consists of a suspension of pigments and / or fillers in an aqueous medium. 4. The polymer composition comprises 60 to 90 parts by weight of a binder copolymer and 10 to 40 parts by weight of an aqueous dispersion rheology control copolymer, the binder copolymer comprising acrylic acid and / or methacrylic acid and C
35 to 60% by weight of ester of _1-8 alcohol, 35 to 35% of vinyl acetate and / or vinyl propionate
60% by weight and up to 10% by weight of copolymerizable monomer (these weight% are based on the total weight of the binder copolymer), and the aqueous dispersion rheology control copolymer comprises acrylic acid and C _{1 -8}
Cross-linking with 40-90% by weight of alcohol ester, 5-40% by weight of acrylic acid and methacrylic acid, 0.5-10% by weight of acrylamide and / or methacrylamide and up to 10% by weight of other copolymerizable monomers. A paper coating colorant according to claim 3 which is derived from 0.05 to 2 wt% of associative monomer, these wt% being based on the total weight of the rheology control copolymer.