JPH0573457B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a glycol-based dispersion of precipitated calcium carbonate. More specifically, in order to improve the coefficient of friction of polyester used as a film or fiber, calcium carbonate is suspended in a glycol such as ethylene glycol, which is a raw material during polyester production, and its dispersibility in glycol, Dispersion Glycol-based dispersion of precipitated calcium carbonate, which is composed of precipitated calcium carbonate that has good stability over time, uniform particle size, and good affinity with polyester, and glycols such as ethylene glycol, propylene glycol, butylene glycol, etc. It's about the body. "Prior Art and Problems" Today, industrially produced polyester,
In particular, polyethylene terephthalate (hereinafter referred to as PET)
) has excellent physical and chemical properties and is widely used in fibers, films, and other molded products. However, contrary to its excellent properties, it has poor slipperiness during the molding process, processing process, or handling of the product itself, resulting in poor workability and
It is known that undesirable problems such as a decrease in product value occur. Many of the causes are
This is due to the high friction coefficient of polyester itself. To solve these problems, many methods have been proposed to improve the surface smoothness of molded products by incorporating fine particles into polyester and giving the surface of the molded product appropriate irregularities, but the compatibility between the fine particles and polyester is insufficient. The transparency and abrasion resistance of the film and fibers were both unsatisfactory. Conventional methods for improving the surface properties of polyester include: Precipitating part or all of the catalyst used during polyester synthesis during the reaction process (internal particle precipitation method) Precipitating fine particles of calcium carbonate, silicon oxide, etc. during or during polymerization Many methods have been proposed for adding the particles later (external particle addition methods). However, since the particles are metal salts of the polyester component, the method for precipitating the internal particles has a certain degree of affinity with polyester, but on the other hand, the method generates particles during the reaction, so the particle amount and particle size are limited. It is difficult to control and prevent the generation of coarse particles. On the other hand, the external particle addition method is a method in which inorganic compound particles insoluble in polyester, such as titanium dioxide, silica, talc, kaolin, calcium carbonate, are added during or after polymerization, and the particle size of these inorganic compounds, If the amount added is appropriately selected and coarse particles are removed by classification or the like before addition, the resultant material is superior to the above method in terms of slipperiness. However, since the affinity between the inorganic particles and the organic component polyester is not sufficient, peeling occurs at the interface between the particles and the polyester during stretching, etc., and voids are generated. Therefore, there are problems to be solved in terms of transparency and abrasion resistance. To improve the affinity between inorganic particles and polyester, surface treatment using a coupling reaction between silane compounds or titanate compounds and inorganic particles has been proposed, but the treatment process is complicated and the effect is not as expected. Various problems arose. In addition, in order to improve the dispersibility of these inorganic compounds in polyester, a glycol slurry of inorganic compound fine particles is prepared and added to the polyester manufacturing process. Also, dispersion stability over time is not good, and if glycol with inorganic compounds suspended in it is stored for a long period of time, the inorganic compounds will settle and form a hard cake, making redispersion difficult. Furthermore, there is also the drawback that inorganic compounds aggregate in glycol or during the production of polyester. The presence of aggregated coarse particles in a polymer can cause yarn breakage during spinning, coarse protrusions and fish eyes in films, and especially drop-outs and S/N when used in films for magnetic tapes. Since this causes a decrease in the ratio, efforts have been made to develop fine particles that do not produce agglomerated coarse particles. Among the fine particles used in these polyesters,
Calcium carbonate is used in many fields as a filler in paper manufacturing, paints, rubber, plastics, etc., as its raw material, limestone, is abundantly produced in Japan. This calcium carbonate is generally divided into two types: heavy calcium carbonate and precipitated calcium carbonate (synthetic calcium carbonate). Heavy calcium carbonate is calcium carbonate prepared into various grades by mechanically pulverizing limestone and classifying the pulverized product.While it has the characteristic of being relatively inexpensive to produce, it has a poor particle size distribution. Calcium carbonate which is broad and has a fineness above a certain level has the disadvantage that it cannot be produced using current crushing and classification techniques. This heavy calcium carbonate has good compatibility with polyester compared to other fine particles used in polyester, and has a relatively low Mohs hardness.
Since it is easy to make particles fine by pulverization, it is often used particularly preferably, and the following methods have conventionally been widely used. Commercially available heavy calcium carbonate, or heavy calcium carbonate whose surface has been surface-treated with fatty acids, resin acids, and alkali metal salts thereof, is subjected to repeated air classification to remove coarse particles of approximately 5 μm or larger, and then
Method of use by dispersing in glycol. A method in which commercially available heavy calcium carbonate is dispersed in glycol, wet-pulverized using a wet-pulverizer such as a sand mill, and then wet-classified to remove coarse particles of approximately 3 μm or larger before use. However, when heavy calcium carbonate as described above is used in polyester, it has the following major drawbacks. (a) Even if a particularly fine grade commercial product of heavy calcium carbonate is selected as the raw material for air classification, the particle size distribution of the raw material heavy calcium carbonate is very broad, and as shown in Figure 8. Coarse particles of about 4 to 6 μm are mixed in. In order to classify and remove these coarse particles, it is difficult to completely remove coarse particles of about 3 μm even if a high-level wind classifier currently available on the market is repeatedly used for classification. Therefore, it is difficult to use heavy calcium carbonate prepared by this method in ultrathin polyester films used in audio tapes and the like. For reference, an electron micrograph of a particularly fine grade of commercially available heavy calcium carbonate (Super #2300, manufactured by Maruo Calcium) is shown in Figure 8 (1000x magnification). (b) When using heavy calcium carbonate whose surface has been treated with fatty acids, resin acids, or their alkali metal salts to increase the classification efficiency of air classification, the compatibility between these surface treatment agents and glycol is not good. , dispersion stability deteriorates in glycol. (c) Since there is a limit to the fineness of commercially available heavy calcium carbonate, which is the raw material for air classification, it is not possible to prepare calcium carbonate with a desired particle size. In the case of: (a) Since raw material heavy calcium carbonate is subjected to attrition and pulverization using a wet pulverizer, it is relatively easy to obtain calcium carbonate having an arbitrary average particle size compared to the method of . Since the grinding method is pulverization, a large amount of particles with a finer degree than necessary is generated, resulting in a broad particle size distribution, which reduces the absolute amount of calcium carbonate that contributes to the original purpose of improving the friction properties of polyester. Not only is this undesirable as the amount of particles decreases, but these ultrafine particles tend to re-agglomerate in glycol to form coarse secondary particles, which tend to adversely affect the physical properties of the polyester film or polyester fiber. (b) Even if the raw material heavy calcium carbonate is wet-pulverized using a wet-type grinder, the raw material heavy will be reduced due to shot pass (a phenomenon in which coarse particles in the material to be crushed are discharged from the wet grinding air without being crushed). Coarse particles of 4 to 6 μm mixed in calcium carbonate may be mixed in calcium carbonate after pulverization, and even if attempts are made to classify and remove these coarse particles using a wet centrifugal classifier, it is not possible to economically classify and remove them. The maximum possible particle size is about 1 μm. Therefore, 1μ
Calcium carbonate prepared by this type of method cannot be used in fields where complete removal of particles coarser than m is required, such as polyester films used in 8 mm video tapes. For the reasons mentioned above, when using calcium carbonate currently prepared from commercially available heavy calcium carbonate as a raw material for polyester, it is difficult to improve the slipperiness of polyester films and polyester fibers any further. In addition, this improved slipperiness affects the running stability of audio tapes, etc., and the tape running stability also subtly affects the sound quality characteristics, which require higher quality, so the following physical properties have been improved. Although calcium carbonate with these properties has been long-awaited by polyester manufacturers, electrical equipment manufacturers, and other parties, the reality is that calcium carbonate with these physical properties has not yet been provided; Calcium carbonate with good dispersibility and dispersion stability over time (ii) Calcium carbonate with uniform particle size of individual particles (iii) Contains no unnecessary particles such as coarse particles or ultra-fine particles, and does not contain glycol Calcium carbonate (iv), which has a sharp particle size distribution. Calcium carbonate (v), which can be freely selected to have any particle size. It has good affinity with polyester, and can be used at the interface between particles and polyester during polyester stretching. Calcium carbonate is difficult to peel off and does not create voids. "Means for Solving the Problems" In view of the above-mentioned circumstances, the present inventors have developed calcium carbonate suitable for producing polyester films and polyester fibers that have particularly good slip properties and are less likely to form voids, that is, have the above-mentioned physical properties. As a result of intensive study on calcium carbonate that satisfies all of (i) to (v),
Surface-treated precipitated calcium carbonate with a specific dispersibility and particle size is treated with a surface treatment agent of a specific composition. By wet-pulverizing the precipitated calcium carbonate in glycol under specific conditions, it is used for polyester. The present invention has been completed based on the discovery that calcium carbonate can be obtained which imparts good properties in some cases. That is, the present invention involves wet pulverization of surface-treated precipitated calcium carbonate prepared by surface-treating precipitated calcium carbonate that satisfies both the requirements (a) and (b) below using the surface treatment agent described in (c) below. A glycol-based precipitated calcium carbonate made of precipitated calcium carbonate and glycol, which is used as a raw material and prepared by wet-pulverizing a glycol slurry made of the wet-pulverized raw material and glycol to meet the requirements (d) below. Dispersion. (a) The primary particle system D ₁ calculated by the following formula from the specific surface area S ₁ measured by the BET method is 0.1 μm
Dx = 60000/2.7Sx - [Dx: Average particle diameter of precipitated calcium carbonate calculated from the specific surface area measured by BET method (μm) Sx: Precipitated calcium carbonate measured by BET method Specific surface area (cm ² /g)] (a) Light transmission centrifugal sedimentation type particle size distribution analyzer SA-CP-
2 (manufactured by Shimadzu Corporation), the ratio R ₁ of the 50% weight average particle diameter d ₁ of the particle size distribution measured in an aqueous system and the above D ₁ satisfies the following formula. R ₁ = d ₁ /D ₁ ≦7 − (c) At least one member selected from α, β monoethylenically unsaturated carboxylic acids and salts thereof, and α, β
Copolymer with monoethylenically unsaturated carboxylic acid ester (A) and/or salt of copolymer with α,β monoethylenically unsaturated carboxylic acid and α,β monoethylenically unsaturated carboxylic acid ester (B ). (d) The ratio R of the primary particle diameter D ₁ and the primary particle diameter D ₂ calculated by the above formula from the specific surface area S ₂ measured by the BET method of precipitated calcium carbonate prepared by wet grinding. ₂ satisfies the following formula, R ₂ =D ₁ /D ₂ , 1<R ₂ ≦10 −. The first feature of the present invention is the use of precipitated calcium carbonate having a specific particle size and degree of dispersion as a raw material for wet grinding. The use of precipitated calcium carbonate having a specific dispersion degree and particle size as a wet-grinding raw material has the following advantages compared to the currently used method of producing a heavy calcium carbonate wet-grinding raw material. It has advantages; Figures 1, 2, and 3 show schematic diagrams of particle shapes before and after crushing when precipitated calcium carbonate is used as a raw material for wet crushing, and when heavy calcium carbonate is used as a raw material for wet crushing. and Fig. 4 respectively. That is, as shown in FIG. 1, when precipitated calcium carbonate having a degree of dispersion above a certain level is used as a raw material for wet grinding, the particle form of the precipitated calcium carbonate has a substantially uniform particle size.
Because they are soft aggregates of primary particles 1, the crushing energy applied to the calcium carbonate particles during the wet crushing process is first consumed in breaking and dispersing the agglomerates between the primary particles, which have weak bonding strength. Unless over-pulverization is continued, each primary particle 1
is less likely to be destroyed or unnecessary ultrafine particles are generated. As a result, as shown in FIG. 2, calcium carbonate having a uniform particle size and a sharp particle size distribution is obtained. On the other hand, as shown in Figures 3 and 4, when heavy calcium carbonate is used as a raw material for wet pulverization, the pulverization energy applied to calcium carbonate particles in the wet pulverization process is limited to two or more coarse primary particles 2. Although it is also used for crushing into coarse primary particles or primary particles having a desired particle size, since crushing and crushing of coarse primary particles requires a large amount of crushing energy, the crushing energy is rather It is likely to be consumed by grinding the surface of the secondary particles 2 and producing a large amount of unnecessary fine particles 3. As is clear from the above, by using precipitated calcium carbonate with a specific particle size and dispersion degree as a wet-grinding raw material, compared to the currently used method of using heavy calcium carbonate as a wet-grinding raw material. As a result, the particle size of calcium carbonate can be arbitrarily selected, and calcium carbonate having a uniform particle size and a sharp particle size distribution can be obtained. In the present invention, the primary particle diameter of the precipitated calcium carbonate, which is the raw material for wet grinding, is calculated by the following formula from the specific surface area S ₁ of the precipitated calcium carbonate measured by the BET _method . 0.1μ
m or more, preferably in the range of 0.2 to 2 μm. Dx=60000/2.7Sx − Dx: Average particle diameter of precipitated calcium carbonate (μ
m) Sx: Specific surface area of precipitated calcium carbonate measured by BET method (cm ² /g) If the primary particle diameter D ₁ of precipitated calcium carbonate, which is the raw material for wet grinding, is less than 0.1 μm, the primary particle Because the cohesive force between the particles is strong and forms large secondary particles (agglomerates of primary particles), it is difficult to completely destroy and disperse the secondary particles even if wet pulverization is repeated within an economical range. and the primary particle diameter is 2μm
, the crushing energy applied to the particles during wet crushing is not consumed only for the destruction of aggregates;
The primary particles are also more likely to be destroyed, and as a result, the variation in particle diameter among the resulting primary particles tends to be large. In addition, the degree of dispersion of the precipitated calcium carbonate, which is the raw material for wet grinding, is the particle size distribution of the precipitated calcium carbonate measured in an aqueous system using a light transmission centrifugal sedimentation type particle size distribution analyzer SA-CP-2 (manufactured by Shimadzu Corporation). 50% weight average particle diameter d ₁ of the precipitated calcium carbonate
The ratio R ₁ of the primary particle diameter D _{1 (described above) calculated from the specific surface area S 1} measured by the BET method is _{R 1}
= d ₁ /D ₁ , R ₁ ≦7, preferably R ₁
If it is ≦4. When precipitated calcium carbonate with R ₁ exceeding 7 is used as a raw material for wet grinding, since the precipitated calcium carbonate is composed of large and strong secondary particles, the secondary particles are easily broken down during the wet grinding process. As a result, a mixture of coarse secondary particles and unnecessarily finely divided ultrafine particles is obtained, which is the same as when heavy calcium carbonate is used as a wet grinding raw material without being broken and dispersed, and thus the object of the present invention cannot be achieved. I can't. The second feature of the present invention resides in the composition of a specific surface treatment agent for surface treatment of precipitated calcium carbonate. The surface treatment agent having a specific composition referred to in the present invention is an α,β monoethylenically unsaturated carboxylic acid or an α,β monoethylenically unsaturated carboxylic acid in which the carboxyl group is an alkali metal, an alkaline earth metal, ammonium, or an amine. Alkali metal salts, alkaline earth metal salts, ammonium salts, neutralized by etc.
At least one selected from amine salts, etc., and α,
Contains the above-mentioned salts of copolymers with β monoethylenically unsaturated carboxylic acid esters, and copolymers of α,β monoethylenically unsaturated carboxylic acids with α,β monoethylenically unsaturated carboxylic esters. Re,
These may be used alone or in a mixture of two or more. In the present invention, α, β monoethylenically unsaturated carboxylic acids include α, β unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; At least one selected from saturated dicarboxylic acids,
Typical α,β monoethylenically unsaturated carboxylic acid esters include acrylic acid, methacrylic acid and other alkyl esters, acrylates and methacrylates having an alkoxy group, acrylates and methacrylates having a cyclohexyl group, There are acrylates and methacrylates having a hydroxy group, polyalkylene glycol monoacrylates, monomethacrylates, etc., and at least one type of α,β monoethylenically unsaturated carboxylic acid ester represented by these is used. In the present invention, methods for treating the surface of calcium carbonate with a surface treatment agent can be broadly classified into the following two methods. Dry processing method Precipitated calcium carbonate powder is placed in a processing container with rotating stirring blades such as a Henschel mixer, the powder is strongly stirred, and the surface treatment agent diluted with water or an organic solvent is added to the powder. Drop the liquid,
A method for producing surface-treated calcium carbonate powder that performs surface treatment using a dry process. Wet treatment method Add a highly concentrated aqueous suspension of precipitated calcium carbonate or a diluted surface treatment agent in water or an organic solvent to a water-containing press cake and stir vigorously to prepare a surface treated highly concentrated calcium carbonate slurry. Then, if necessary, the surface-treated high-concentration calcium carbonate slurry is passed through a wet grinder such as a sand grinder for stronger surface treatment, and then the surface-treated high-concentration calcium carbonate slurry is dried using a drum dryer or the like. A method for producing surface-treated calcium carbonate powder by drying using a machine and then pulverizing it using a pulverizer, performing a wet surface treatment. Regardless of which of these two processing methods is used,
Although the object of the present invention can be achieved, in order to uniformly apply a surface treatment agent to the surface of each calcium carbonate particle and achieve the object of the present invention to a higher degree, it is better to use a wet treatment method, which is the method of preferable. The surface treatment agent used to surface treat the calcium carbonate surface by these treatment methods is as described above, but in order to more firmly apply the surface treatment agent to the surface of the calcium carbonate particles, it is necessary to combine the surface treatment agent and calcium carbonate. It is desirable that the particle surfaces be strongly bonded by a chemical reaction, and for this purpose, a surface treatment agent that has residual active carboxyl groups that are reactive with calcium carbonate, i.e., α, β monoethylene, is used. In alkali metal salts, alkaline earth metal salts, ammonium salts, amine salts, etc. of α,β monoethylenically unsaturated carboxylic acids copolymerized with polyethylenically unsaturated carboxylic acid esters, alkali metals, alkaline earth metals, ammonium ,
The total amount of carboxyl groups neutralized with amine etc. is 100% of the total amount of all carboxyl groups in the copolymer.
%, more preferably 90% or less. The same applies to the case where a copolymer of α, β monoethylenically unsaturated carboxylic acid and its ester is neutralized to form a salt. Further, the proportion of α, β monoethylenically unsaturated carboxylic acid ester in the entire copolymer is preferably 2 mol% or more and 95 mol% or less of the entire copolymer, and if it is less than 2 mol%, calcium carbonate and polyester If the affinity exceeds 95 mol %, it is difficult to obtain sufficiently satisfactory results in terms of dispersion stability of a highly concentrated aqueous slurry for surface treatment of calcium carbonate in the surface treatment method. The surface treatment amount of the surface treatment agent is preferably 0.01% by weight or more and 30% by weight or less based on calcium carbonate as a pure component; if it is less than 0.01% by weight, it is difficult to obtain sufficiently satisfactory results in terms of treatment effect. Moreover, if it exceeds 30% by weight, it is not only economically disadvantageous but may also have an adverse effect on the polyester itself. Furthermore, there are no particular regulations regarding the temperature at which these surface treatment agents are applied to the surface of calcium carbonate, but in order to achieve a stronger surface treatment, at least
The surface treatment is preferably carried out at a treatment system temperature of 30°C or higher, preferably 50°C or higher. Conventional methods can be used to raise the temperature of the surface treatment system to high temperatures.For example, in the treatment method, hot water or steam may be passed into the external jacket of a treatment container such as a Henschel mixer to heat it; In this method, the surface-treated calcium carbonate slurry may be heated by external heating. The third feature of the present invention resides in specific wet pulverization conditions in the step of wet pulverizing precipitated calcium carbonate. That is, the specific wet pulverization conditions according to the method of the present invention are calculated by the above formula from the specific surface area measured by the BET method of each of the precipitated calcium carbonate as a wet pulverized raw material and the precipitated calcium carbonate prepared by wet pulverization. Ratio R ₂ of primary particles D ₁ and D ₂
R ₂ = D ₁ /D ₂ , 1<R ₂ ≦10 D ₂ : Primary particle diameter calculated from the specific surface area S ₂ measured by the BET method of precipitated calcium carbonate prepared by wet grinding ( μm) (Figs. 5 and 6). On the other hand, if the wet grinding conditions are set so that R ₂ exceeds 10, it will result in over-grinding, the primary particle surface will be significantly ground, and a large amount of unnecessary ultra-fine particles 3 will be generated, which is undesirable. . (Figures 5 and 7). Therefore, the specific wet grinding conditions according to the method of the invention result in calcium carbonate that does not contain large amounts of unnecessary ultrafine particles. Therefore, the calcium carbonate prepared by the method of the present invention, that is, the calcium carbonate prepared so as to have all of the above-mentioned three characteristics, has various properties that are long-awaited by the above-mentioned polyester manufacturers, electrical machinery manufacturers, etc. It satisfies all the characteristics. Examples of the glycol used in the present invention include ethylene glycol, propylene glycol, butylene glycol, and the like. Precipitated calcium carbonate, which is a raw material for wet grinding used in the present invention, is prepared by reacting quicklime obtained by calcining limestone at high temperatures with water to prepare lime milk, and then passing carbon dioxide gas generated during limestone calcining into the lime milk. carbon dioxide gas combination process to synthesize calcium carbonate,
Synthetic calcium carbonate is prepared by chemical methods such as the lime soda process in which milk of lime is reacted with soda carbonate, and the soda process in which calcium chloride is reacted with sodium carbonate.There are no particular restrictions on these manufacturing processes, but the precipitation It goes without saying that the carbonation method and manufacturing method must be such that the calcium carbonate produced must satisfy both of the two requirements of 0.1≦D ₁ and R ₁ ≦7 as described above. For example, when producing precipitated calcium carbonate, which is a wet-pulverized raw material used in the present invention, by a carbon dioxide method, the following methods can be considered, but the method is not particularly limited to these methods. (1) Prepare an aqueous suspension of ultrafine calcium carbonate with a particle size of less than 0.1 μm using a conventional method, control the pH to prepare the aqueous suspension of ultrafine calcium carbonate, and control the pH to obtain an aqueous dispersion of the ultrafine calcium carbonate. carbon dioxide gas and primary carbonated lime milk (lime milk that has previously been partially carbonated) are introduced or dropped into the ultrafine calcium carbonate aqueous dispersion so that the pH of the system is within a specific range. , a method of sequentially growing the particle size using the ultrafine calcium carbonate as a core (Special Publication No. 1983-
43331) and similar methods. (2) Among the above (1), methods of changing primary carbonated milk of lime to milk of lime, and methods similar thereto. (3) Spray milk of lime into carbon dioxide gas under specific conditions to perform a carbonation reaction, prepare an ultrafine calcium carbonate aqueous suspension of less than 0.1 μm, and add a certain proportion to the ultrafine calcium carbonate aqueous suspension. After mixing the milk of lime, the mixture is sprayed into carbon dioxide gas again, and this operation is repeated to gradually increase the particle size using the ultrafine calcium carbonate as the core (Special Publication 1973).
-28397) and similar methods. (4) A method in which strontium or barium salt is used in the carbonation process to produce precipitated calcium carbonate by introducing carbon dioxide gas into milk of lime, in order to improve the degree of dispersion of the resulting calcium carbonate ( JP-A-59-69425) (5) Stir a precipitated calcium carbonate aqueous suspension obtained by a conventional method, and use carbon dioxide gas and milk of lime to create a system.
A method for improving the degree of dispersion of the precipitated calcium carbonate by maintaining the pH within a specific range. The wet crusher used in the present invention is a container filled with microparticles such as natural or synthetic mineral sand, hard glass microparticles, hard plastic microparticles, metal microparticles, etc., and the microparticles are crushed into a disk (plate shape). ,
It is a device that performs pulverization processing by refluxing or passing the dispersion of the processed material while mechanically stirring it through a stirring blade such as a bar (rod shape) or screw.
For example, there are devices called sand mills, universal mills, attritors, dyno mills, etc. The average particle size of the fine particles used in the wet grinder is preferably about 5 mm or less, and about 3 mm or less. There is no particular limit to the concentration of precipitated calcium carbonate in the wet grinding process for glycol-based slurries, but judging from economic efficiency, grinding efficiency, and viscosity of glycol-based slurry, it is set at 20% by weight.
More than 80% by weight is desirable. In the present invention, the primary particle size calculated from the specific surface area measured by the BET method of precipitated calcium carbonate, which is a raw material for wet pulverization, refers to the primary particle size calculated from the specific surface area measured by the BET method of precipitated calcium carbonate, which is the raw material for wet pulverization, regardless of whether it is water-based or glycol-based. Calcium carbonate refers to the primary particle size of precipitated calcium carbonate powder obtained by drying and powdering an aqueous suspension of precipitated calcium carbonate prepared by carbonation using the carbon dioxide method or solution method. The 50% weight average particle system _d1 measured by the centrifugal sedimentation light transmission type particle size distribution analyzer in the present invention was measured and calculated in the following manner. Measuring model: SA-CP-2 (manufactured by Shimadzu Corporation) Measuring method: Solvent: Preliminary dispersion of 0.2% sodium hexametaphosphate aqueous solution: KM SHAKER MODEL V-5
Shake particle size distribution analyzer (manufactured by IWAKI CO., LTD) for 10 minutes Rotation speed: 1200rpm Liquid level height 1cm from the bottom of the cell Measurement temperature: 25℃ Measurement method: Particle size distribution measurement results as shown in the calculation example below ( One case)

[Table] Therefore, the 50% weight average diameter of the above particle size distribution is
It is set to 0.706 μm. "Examples" The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited by these in any way. Incidentally, precipitated calcium carbonate used in Examples and Comparative Examples was prepared in the following manner. Precipitated calcium carbonate A: Temperature 15℃, _CO2 concentration in ^7.2m3 lime milk with specific gravity 1.070
25% furnace gas (hereinafter abbreviated as CO ₂ gas) to 20 m ³ /
The carbonation reaction was completed at a flow rate of min. After the carbonation reaction, the temperature of the system was adjusted to 50±5°C and the pH was adjusted to 10±0.5 using CO ₂ gas and milk of lime, and the mixture was stirred for 24 hours to form a viscous precipitated calcium carbonate A aqueous dispersion with a viscosity of 2000 cps. I got it. The precipitated calcium carbonate A
Table 1 shows the specific surface area and particle size distribution determined by the BET method. Precipitated calcium carbonate B: Precipitated calcium carbonate A adjusted to 50℃±5℃
Water dispersion (solid content concentration 14.9%) specific gravity 1.070 per 4 ^m3
of milk of lime at a flow rate of 0.6 m ³ /hr, and at the same time
CO ₂ gas was passed through the system, and the carbonation reaction was carried out under stirring conditions at a system pH of 10±0.5. When the total amount of lime milk reached 32 m ³ , the dropping of lime milk was stopped, and CO ₂ gas was introduced until the pH of the system reached 7.0 to obtain an aqueous dispersion of precipitated calcium carbonate B. The precipitated calcium carbonate B
Table 1 shows the specific surface area and particle size distribution determined by the BET method. Precipitated calcium carbonate C: Precipitated calcium carbonate A adjusted to 50℃±5℃
Water dispersion (solid content concentration 14.9%) Specific gravity 1.070 per ³ m3
of milk of lime at a flow rate of 0.6 m ³ /hr, and at the same time
CO ₂ gas was passed through the system, and the carbonation reaction was carried out under stirring conditions at a system pH of 10±0.5. When the total amount of lime milk reached 60 m ³ , the dropping of lime milk was stopped, and CO ₂ gas was introduced until the pH of the system reached 7.0 to obtain an aqueous dispersion of precipitated calcium carbonate C. of the precipitated calcium carbonate C
Table 1 shows the specific surface area and particle size distribution determined by the BET method. Precipitated calcium carbonate D: Add 12 kg of strontium carbonate to 43 m ³ of milk of lime at a temperature of 30°C and a specific gravity of 1.080, and after stirring, add 5 ml of CO ₂ gas.
Conducting at a flow rate of m ³ /min, the carbonation reaction takes place and the system
The carbonation reaction was stopped at pH 8.0. After that, the system was stirred at a temperature of 60°C ± 5°C to elute the remaining alkali.
Partially adjust the PH of the system to 10±1 using CO ₂ gas, and after stirring for 24 hours, adjust the PH of the system using CO ₂ gas.
was set to 7.0, and an aqueous dispersion of precipitated calcium carbonate D was obtained. Table 1 shows the specific surface area and particle size distribution of the precipitated calcium carbonate D obtained by the BET method. Precipitated calcium carbonate E: CO ₂ gas is passed through 7.2 m ³ of lime milk with a specific gravity of 1.080 at a temperature of 30°C at a particle speed of 2 m ³ /min to perform a carbonation reaction.
The carbonation reaction was stopped when the pH of the system was 6.8, and an aqueous dispersion of precipitated calcium carbonate E was obtained. Table 1 shows the specific surface area and particle size distribution of the precipitated calcium carbonate E determined by the BET method. The surface treatment agents used in Examples and Comparative Examples are listed below; Surface treatment agent 1: Copolymer of 50 mol% acrylic acid and 50 mol% polyethylene glycol monomethacrylate Surface treatment agent 2: 80 mol% acrylic acid and An ammonium salt of a copolymer of 20% by mole of propyl acrylate, in which 85% of all carboxyl groups in the copolymer are neutralized with ammonium Surface treatment agent 3: 30% by mole of acrylic acid and 2 Copolymer containing 70 mol% of hydroxyethyl acrylate Surface treatment agent 4: Sodium salt of surface treatment agent 3, in which 50% of all carboxyl groups in the copolymer are neutralized with sodium Surface treatment agent 5: An amine salt of a copolymer of 70 mol% acrylic acid, 10 mol% maleic acid, and 20 mol% methoxyethyl acrylate, in which 40% of the total carboxyl groups in the copolymer are neutralized with amine. Treatment agent 6: A sodium salt of a copolymer of 70 mol% acrylic acid, 10 mol% itaconic acid, and 20 mol% cyclohexyl acrylate, in which 40% of the total carboxyl groups in the copolymer are neutralized with sodium. Irumono surface treatment agent 7: A sodium salt of a copolymer of 90 mol% acrylic acid and 10 mol% methoxypolyethylene glycol polypropylene glycol monomethacrylate, in which 100% of all carboxyl groups in the copolymer are neutralized with sodium. Surface treatment agent 8: A sodium salt of a polymer of acrylic acid, in which 100% of all carboxyl groups in the polymer are neutralized with sodium.Surface treatment agent 9: Sodium stearate surface treatment Agent 10: Monomer of ethylene glycol monomethacrylate

【table】

[Table] Example 1 Precipitated calcium carbonate B aqueous dispersion (concentration 14.9
%) using a filter press, and the resulting press cake (solid content concentration 60%) is placed in an external heating treatment tank. A high concentration slurry of surface-treated calcium carbonate of precipitated calcium carbonate B having a solid content concentration of 60% was prepared by adding 1% by weight of the precipitated calcium carbonate B and stirring vigorously. The high concentration surface-treated calcium carbonate slurry was dried and powdered using a spray dryer to obtain a surface-treated powder of precipitated calcium carbonate B. This surface-treated powder of precipitated calcium carbonate B was poured into 50 kg of ethylene glycol (manufactured by Mitsubishi Yuka, fiber grade A) and stirred to prepare an ethylene glycol slurry as a wet-pulverized raw material.
Wet mill (dyno mill) with a flow rate of cc/min
Pilot type, manufactured by WAB, glass beads with media 0.6 to 0.9 mmφ, media filling rate 80%, rotation speed
1500 rpm (the same applies hereinafter) and wet milling was performed to prepare an ethylene glycol dispersion of precipitated calcium carbonate B. The 50% weight average diameters d ₂ , S ₂ , D ₂ , and R ₂ calculated from the particle size distribution measurement results and particle size distribution measurement results of the dispersion using SA-CP-2 were calculated as the second
Shown in the table. In addition, the electron micrograph of the dispersion is
Shown in Figure (10000x) and Figure 10 (300x). From the results in Table 2 and Figures 9 and 10, it is clear that the ethylene glycol dispersion of precipitated calcium carbonate B prepared in Example 1 has relatively uniform individual particle sizes, and Compared to the comparative example, it is confirmed that the particle size distribution is sharp, there are fewer unnecessary fine particles, and there is no coexistence of coarse particles of 2 to 3 μm. Example 2 An ethylene glycol dispersion of precipitated calcium carbonate C was prepared in the same manner as in Example 1, except that the precipitated calcium carbonate B was changed to the same C and the surface treatment agent 1 was changed to the same 3. Table 2 shows the particle size distribution measurement results of the dispersion using SA-CP-2, d ₂ , S ₂ , D ₂ , and R ₂ . Further, an electron micrograph of the ethylene glycol dispersion is shown in FIG. 11 (10,000 times magnification). Example 3 Surface treatment agent 1 was added to precipitated calcium carbonate B to the same D.
6, the flow rate of the ethylene glycol slurry in the wet grinder is changed from 120c.c./min to 250c.c./min.
An ethylene glycol dispersion of precipitated calcium carbonate D was prepared in the same manner as in Example 1, except that the flow rate was changed to cc/min. Table 2 shows the particle size distribution measurement results of the dispersion using SA-CP-2, d ₂ , S ₂ , D ₂ , and R ₂ . Example 4 The surface treatment agent 1 was changed to 2, and the surface treatment temperature was 70℃ to 50℃.
A highly concentrated slurry of surface-treated calcium carbonate of precipitated calcium carbonate B was prepared in the same manner as in Example 1, except that the temperature was changed. 500% of the high concentration slurry
Pass through a wet pulverizer at a flow rate of cc/min, then dry and powder using a spray dryer.
A surface-treated powder of precipitated calcium carbonate B was obtained.
Using this surface-treated powder of precipitated calcium carbonate B as a wet-pulverized raw material, an ethylene glycol dispersion of precipitated calcium carbonate B was prepared in the same manner as in Example 1. Table 2 shows the particle size distribution measurement results of the dispersion using SA-CP-2, d ₂ , S ₂ , D ₂ , and R ₂ . Examples 5, 6, 7 Same as Example 4 except that the surface treatment agent 2 was changed to 4 (Example 5), 5 (Example 6), or 7 (Example 7) Ethylene glycol dispersions of precipitated calcium carbonate B were prepared using the method described above. Table 2 shows the particle size distribution measurement results of the dispersion using SA-CP-2, d ₂ , S ₂ , D ₂ , and R ₂ . Comparative example 1 Calcium carbonate B aqueous dispersion (concentration 14.9
%) was dehydrated using a filter press, and the resulting press cake was dried using a paddle dryer and then dry-pulverized to obtain 50 kg of dry powder of precipitated calcium carbonate B. 50 kg of this precipitated calcium carbonate B was poured into 50 kg of ethylene glycol (manufactured by Mitsubishi Yuka, fiber grade A) and stirred to prepare an ethylene glycol slurry as a raw material for wet grinding.
Wet mill (dyno mill) with a flow rate of 120c.c./min
Pilot type, manufactured by WAB, glass beads with media 0.6 to 0.9 mmφ, media filling rate 80%, rotation speed approx.
1500 rpm) and wet milling was performed to prepare an ethylene glycol dispersion of precipitated calcium carbonate B. 50 calculated from the particle size distribution measurement results of the dispersion using SA-CP-2 and the particle size distribution measurement results.
The % weight average diameters d ₂ , S ₂ , D ₂ and R ₂ are shown in Table 2.
Electron micrographs of the ethylene glycol dispersion are shown in FIG. 12 (5000 times) and FIG. 13 (400 times). Comparative Example 2 Example 1 except that surface treatment agent 1 was changed to surface treatment agent 8.
An ethylene glycol dispersion of precipitated calcium carbonate B was prepared in the same manner as above. SA of the dispersion
- Particle size distribution measurement results by CP-2, d ₂ , S ₂ , D ₂ ,
R ₂ is shown in Table 2. Comparative Example 3 Calcium carbonate B aqueous dispersion (concentration 14.9
%), add 3% by weight of a warm water diluted solution of surface treatment agent 9 based on the solid content of calcium carbonate as a pure content, stir vigorously, and then dehydrate with a filter press. dried using a dry grinder, crushed using a dry grinder,
A surface-treated powder of precipitated calcium carbonate B was obtained.
50 kg of surface treated powder of this precipitated calcium carbonate B
was added to 50 kg of ethylene glycol, and then
Wet pulverization was performed in the same manner as in Example 1 to prepare an ethylene glycol dispersion of precipitated calcium carbonate B. 50 calculated from the particle size distribution measurement results of the dispersion using SA-CP-2 and the particle size distribution measurement results.
The % weight average diameters d ₂ , S ₂ , D ₂ and R ₂ are shown in Table 2. Comparative example 4 Specific surface area by DET method is 74300cm ² /g, D ₁ =
0.30μm heavy calcium carbonate “Super #2300”
(manufactured by Maruo Calcium) was poured into 50 kg of ethylene glycol (manufactured by Mitsubishi Yuka, fiber grade A) and stirred to prepare an ethylene glycol slurry as a raw material for wet grinding. The mixture was passed through a pulverizer (Dyno Mill Pilot type, manufactured by WAB) and subjected to wet pulverization to prepare an ethylene glycol dispersion of heavy calcium carbonate.
Table 2 shows the particle size distribution measurement results of the dispersion using SA-CP-2, d ₂ , S ₂ , D ₂ , and R ₂ . Further, an electron micrograph of the dispersion is shown in FIG. 14 (10,000 times magnification). From the results in Table 2 and FIG. 14, the ethylene glycol dispersion of heavy calcium carbonate prepared in Comparative Example 4 was compared with the ethylene glycol dispersion of precipitated calcium carbonate prepared in Example 1. Although the d ₂ is almost the same, the particle size distribution is broad, and it is confirmed that coarse particles of about 2 to 3 μm are mixed. Comparative Example 5 Aqueous dispersion of calcium carbonate E made by precipitation (concentration 16.8
%) was dehydrated using a filter press, and the resulting press cake was dried using a paddle dryer and then dry-pulverized to obtain 50 kg of dry powder of precipitated calcium carbonate E. 50 kg of this precipitated calcium carbonate E was poured into 50 kg of ethylene glycol (manufactured by Mitsubishi Yuka, fiber grade A) and stirred to prepare an ethylene glycol slurry as a raw material for wet grinding.
Wet pulverization was repeated twice at a flow rate of cc/min, and wet pulverization was performed to obtain precipitated calcium carbonate E.
An ethylene glycol dispersion was prepared. Particle size distribution measurement results of the dispersion using SA-CP-2, d ₂ ,
S ₂ , D ₂ , and R ₂ are shown in Table 2. Further, electron micrographs of the dispersion are shown in Fig. 16 (5000x) and Fig. 17 (2000x), and Fig. 15 is an electron micrograph of precipitated calcium carbonate E (before wet pulverization), which is a raw material for wet pulverization. (10000x magnification). Judging from the results in Table 2 and Figures 15, 16, and 17, the ethylene glycol dispersion of precipitated calcium carbonate E prepared in Comparative Example 5 has R ₁ >7 ( (See Table 1) In other words, precipitated calcium carbonate E has extremely high cohesiveness between primary particles and forms large secondary particles.
5μm, even though the wet grinding process in the ethylene glycol system employs grinding conditions that are approximately four times that of Example 1.
It is confirmed that some coarse secondary particles are mixed. Comparative Example 6 Same as Example 2, except that in the wet grinding process in the ethylene glycol system, the ethylene glycol slurry as the wet grinding raw material was repeatedly passed through the wet grinder three times at a flow rate of 60 c.c./min. An ethylene glycol dispersion of precipitated calcium carbonate C was prepared in the following manner. SA-CP of the dispersion
-2 particle size distribution measurement results, d ₂ , S ₂ , D ₂ , R ₂
are shown in Table 2. Further, an electron micrograph of the dispersion is shown in FIG. 18 (10,000 times magnification). From the results in FIG. 18, it can be seen that the ethylene glycol dispersion of precipitated calcium carbonate C prepared in Comparative Example 6 was the same as that in Example 2.
It is confirmed that a large amount of unnecessary fine particles are produced compared to the ethylene glycol dispersion of precipitated calcium carbonate C prepared in . Comparative Example 7 After putting 50 kg of dry powder of surface-treated precipitated calcium carbonate D used in Example 3 into 50 kg of ethylene glycol, instead of performing wet pulverization using a wet pulverizer, a stirring blade diameter of 10 cm and a circumferential speed of 62 m/cm were used. A dispersion of precipitated calcium carbonate D in ethylene glycol was prepared by stirring vigorously for 10 minutes using a dissolver type stirrer of min. Table 2 shows the particle size distribution measurement results of the dispersion using SA-CP-2. An electron micrograph of the dispersion is shown in FIG. 19 (1000x magnification). From the results shown in FIG. 19, it is confirmed that the ethylene glycol dispersion of precipitated calcium carbonate D prepared in Comparative Example 7 contains unnecessary coarse secondary particles of 5 to 10 μm. Comparative Example 8 Aqueous dispersion of calcium carbonate A made by sedimentation (concentration 14.9
%) using a filter press, the resulting press cake (solid content concentration 57%) was placed in an external heating treatment tank, and the surface treatment agent 1 was added to the press cake in a pure form relative to the calcium carbonate solid content. A high concentration slurry of surface-treated calcium carbonate of precipitated calcium carbonate A having a solid content concentration of 57% was prepared at a surface treatment temperature of 70° C. by adding 2% by weight and stirring vigorously. The high-concentration surface-treated calcium carbonate slurry was dried and powdered using a spray dryer to obtain a surface-treated powder of precipitated calcium carbonate A. 30 kg of surface-treated powder of precipitated calcium carbonate A was poured into 70 kg of ethylene glycol and stirred to prepare an ethylene glycol slurry as a raw material for wet pulverization, and the slurry was repeatedly subjected to a wet pulverizer at a flow rate of 60 c.c./min. The mixture was passed twice and wet-milled to prepare an ethylene glycol dispersion of precipitated calcium carbonate A. Table 2 shows the particle size distribution measurement results of the dispersion using SA-CP-2, d ₂ , S ₂ , D ₂ , and R ₂ . Further, an electron micrograph of the dispersion is shown in FIG. 20 (1000x magnification). From the results shown in Figure 20, it was confirmed that the ethylene glycol dispersion of precipitated calcium carbonate A prepared in Comparative Example 8 contained a large number of secondary particles having a particle size of about 2 to 5 μm. Ru. Comparative Example 9 Same as Example 1 except that the mixture was changed to a mixture of surface treatment agent 1, surface treatment agent 8, and surface treatment agent 10 (mixture in equimolar ratio and no polymerization initiator was added).
An ethylene glycol dispersion of calcium carbonate A was prepared in the same manner as described above. Application example 1 Long-term stability of ethylene glycol dispersions 1 each of the ethylene glycol dispersions of calcium carbonate prepared in Examples 1 to 7 and Comparative Examples 1 to 9
was placed in a measuring cylinder of No. 1 and allowed to stand still for 60 days, and then the state of separation of calcium carbonate and ethylene glycol in the calcium carbonate ethylene glycol dispersion in each measuring cylinder and the state of the calcium carbonate that had settled at the bottom of the measuring cylinder were determined. Observed. The results of these measurements are shown in Table 2. The evaluation criteria during observation are as follows; ○: There is almost no separation of calcium carbonate and ethylene glycol, and the calcium carbonate that has settled at the bottom of the graduated cylinder is soft and can be easily redispersed. △: There is no separation between calcium carbonate and ethylene glycol. Calcium carbonate is separated from ethylene glycol, but the calcium carbonate that has settled at the bottom of the measuring cylinder is relatively soft and can be redispersed. Application example 2. Affinity between calcium carbonate particles and PET resin 100 parts by weight of dimethyl terephthalate and 70 parts by weight of ethylene glycol are mixed with manganese acetate tetrahydrate.
After carrying out transesterification using 0.035 parts as a catalyst in a conventional manner, the ethylene glycol dispersions of calcium carbonate prepared in Examples 1 to 7 and Comparative Examples 1 to 9 were transesterified until the calcium carbonate concentration was 5000 ppm based on the polymer.
The mixture was added under stirring until the mixture was mixed. After that, a polycondensation reaction was performed in a conventional manner under high temperature vacuum, and the intrinsic viscosity was 0.630.
of polyethylene terephthalate was obtained. This polymer was melt extruded at 290°C and 3.5 mm in machine direction at 90°C.
After stretching 3.5 times in the transverse direction at 130°C, heat treatment was performed at 220°C to produce a film with a thickness of 15 μm.
After removing the surface polymer by etching these films and exposing the calcium carbonate,
The affinity between calcium carbonate and polyester was observed by measuring the void diameter (Db) and the calcium carbonate diameter (Dc) under a scanning electron microscope at 20,000 times magnification. The observation results are shown in Table 2.
The evaluation criteria during observation are as follows; ◎: 1≦Db/Dc<1.2 Voids do not exist or are very small ○: 1.2≦Db/Dc<1.5 △: 1.5≦Db/Dc< 3.0 △: 3.0≦Db/Dc<4.0 Application example 3 Passability of ethylene glycol dispersion through filter Each of the ethylene glycol dispersions prepared in Examples 1 to 7 and Comparative Examples 1 to 9 was further diluted with ethylene glycol, and each 400ml of 10wt% dilution of
Prepared. After preparing 200 ml of these 10 wt% diluted solutions and 24 hours later, they were filtered under pressure using an 8 μm membrane filter (manufactured by Millipore) at 2 Kg/cm ² .
The amount of passage was measured. The measurement results are shown in Table 2. Application example 4 Dispersibility of calcium carbonate particles in PET resin Small amounts of various polymers prepared in application example 2 were
The polymer was sandwiched between two cover glasses, melt-pressed at 280°C, rapidly cooled, and then observed under a microscope. Multiple primary particles agglomerated together and the parts where the particle size became coarse were determined to be coarse particles. The dispersibility of the particles inside was investigated. The dispersibility of particles was determined as follows by observing coarse particles having a size more than four times the average primary particle diameter present in 1 mm ² . The determination results are shown in Table 2. As the average primary particle diameter, the 50% weight average diameter _d2 of the particle size distribution was adopted. ◎: 10 coarse particles/mm ² or less ○: 11 coarse particles/mm ² or more and 30 pieces/mm 2 or less △: 31 coarse particles/mm ^{2 or} more and 50 pieces/mm ² or less ×: Coarse particles 51 pieces/ ^mm2 or more

【table】

[Table] From the results in Table 2, the ethylene glycol dispersion of precipitated calcium carbonate B prepared in Example 1 has good dispersion stability over time and good filter passability;
Moreover, when used in the production of PET resin, it is confirmed that the dispersibility in PET resin and the affinity with PET resin are good. Precipitated calcium carbonate B prepared in Comparative Example 1
The ethylene glycol dispersion differs from the ethylene glycol dispersion of precipitated calcium carbonate B prepared in Example 1 only in that surface treatment agent 1 is not used. Compared to the preparation of Example 1, the preparation of Comparative Example 1 has poor dispersion stability over time of the ethylene glycol dispersion, and the PET resin prepared using this preparation has poor calcium carbonate.
Application example 1 is that the affinity with PET resin is poor.
This is clear from the results of Application Example 2. Precipitated calcium carbonate B prepared in Comparative Example 2
In PET resin prepared using ethylene glycol dispersion, calcium carbonate particles and
Application example 2 is that the affinity with PET resin is poor.
It is clear from the results. Precipitated calcium carbonate B prepared in Comparative Example 3
The ethylene glycol dispersions of Examples 1, 4,
Although d ₂ is almost similar compared to 5, 6, and 7, the particle size distribution is broad and
It is confirmed that many coarse particles larger than 6 μm are mixed in. Moreover, from the results of Application Examples 1 and 2, the dispersion stability over time of the ethylene glycol dispersion of precipitated calcium carbonate B prepared in Comparative Example 3 was poor, and the dispersion of calcium carbonate in ethylene glycol was poor. The affinity between calcium carbonate particles and PET resin in PET resin prepared using PET resin is also poor. The ethylene glycol dispersion of heavy calcium carbonate prepared in Comparative Example 4 had extremely poor dispersion stability over time and filter passability. Application examples 1 and 2 show that the dispersibility of calcium carbonate particles and the affinity between calcium carbonate and PET resin are extremely poor.
This is clear from results 3 and 4. Precipitated calcium carbonate E prepared in Comparative Example 5
This ethylene glycol dispersion has extremely poor dispersion stability over time and filter permeability, and the dispersibility of calcium carbonate particles and calcium carbonate in PET resin using this ethylene glycol dispersion of precipitated calcium carbonate E is extremely poor.
It is confirmed from the results of Application Examples 1, 2, 3, and 4 that the affinity with PET resin is also extremely poor. From the results of Application Example 4, it was confirmed that the ethylene glycol dispersion of precipitated calcium carbonate C prepared in Comparative Example 6 had poor dispersibility of calcium carbonate particles in PET resin prepared using this dispersion. be done. From the results of Application Example 4, it was confirmed that the ethylene glycol dispersion of precipitated calcium carbonate A prepared in Comparative Example 8 had poor dispersibility of calcium carbonate particles in PET resin prepared using this dispersion. be done. Precipitated calcium carbonate B prepared in Comparative Example 9
It has been confirmed that the ethylene glycol dispersion has poor dispersibility of calcium carbonate particles in the PET resin prepared using this dispersion. "Action/Effect" As described above, the present invention provides a glycol-based dispersion of precipitated calcium carbonate that has good dispersibility in glycol, stability over time of dispersion, uniformity of particle size, and affinity with polyester. It also improves the surface properties of polyester.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic diagrams of wet pulverization of precipitated calcium carbonate, Figures 3 and 4 are schematic diagrams of wet pulverization of heavy calcium carbonate,
Figures 5 and 6 show the precipitated calcium carbonate of the present invention obtained by wet grinding, Figure 7 shows the precipitated calcium carbonate when R ₂ > 10, and Figures 8 to 20 show the precipitated calcium carbonate of the present invention obtained by wet grinding. It is an electron micrograph showing the particle structure. 1...Primary particles with substantially uniform particle size, 2...Coarse primary particles, 3...Fine particles.

Claims (1)

[Scope of Claims] 1. A surface-treated precipitated calcium carbonate prepared by surface-treating precipitated calcium carbonate that satisfies both the requirements (a) and (b) below using the surface treatment agent described in (c) below. Precipitated calcium carbonate consisting of precipitated calcium carbonate and glycol is used as a wet-milled raw material and prepared by wet-milling a glycol slurry consisting of the wet-milled raw material and glycol so as to meet the requirements (d) below. Glycol dispersion. (a) The primary particle system D ₁ calculated by the following formula from the specific surface area S ₁ measured by the BET method is 0.1 μm
Dx = 60000/2.7Sx − [Dx: Average particle diameter of precipitated calcium carbonate calculated from the specific surface area measured by BET method (μm) Sx: Precipitated calcium carbonate measured by BET method Specific surface area (cm ² /g)] (a) Light transmission centrifugal sedimentation type particle size distribution analyzer SA-CP-
The ratio of the 50% weight average particle diameter d ₁ of the particle size distribution measured in an aqueous system using 2 (manufactured by Shimadzu Corporation) and the above D ₁
R ₁ must satisfy the following formula. R ₁ = d ₁ /D ₁ ≦7 − (c) At least one member selected from α, β monoethylenically unsaturated carboxylic acids and salts thereof, and α, β
Copolymer with monoethylenically unsaturated carboxylic acid ester (A) and/or salt of copolymer with α,β monoethylenically unsaturated carboxylic acid and α,β monoethylenically unsaturated carboxylic acid ester (B ). (d) The ratio R of the primary particle diameter D ₁ and the primary particle diameter D ₂ calculated by the above formula from the specific surface area S ₂ measured by the BET method of precipitated calcium carbonate prepared by wet grinding. ₂ satisfies the following formula, R ₂ = D ₁ /D ₂ , 1 < R ₂ ≦10 − 2 In the above (c), the proportion of α, β monoethylenically unsaturated carboxylic acid ester in the entire copolymer is The glycol-based dispersion according to claim 1, wherein the glycol dispersion is 2 mol% or more and 95 mol% or less of the entire copolymer. 3. The amount of surface treatment of the copolymer used to surface treat calcium carbonate is
The glycol-based dispersion according to claim 1, which has a content of 0.01 wt% or more and 30 wt% or less.