Heavy calcium carbonate, production method therefor, and resin composition containing said calcium carbonate

Abstract

A surface-treated heavy calcium carbonate is provided which is useful for a film exactly controlled in its pore diameter and for easily hydrolyzable polyester resins. A heavy calcium carbonate is also provided which is compounded in a curable resin such as a one-component moisture-curable adhesive and a sealant either without any pre-drying treatment or by simple pre-drying treatment. A surface-treated heavy calcium carbonate satisfying 13,000≤A≤25,000, 0.8≤B≤3.0, C≥0.55, and 0≤D1≤1000, or 8,000≤A≤25,000, 0.8≤B≤15, 0≤C1≤1000, and 0≤C2≤150 wherein: A: specific surface area (cm.sup.2/g), B: average particle diameter (μm): 50% particle diameter (d50) (μm), C: 10% particle diameter (μm), D1, C1: water content at between 25° C. and 300° C. by a Karl-Fischer method (heating vaporization method) (ppm), and C2: water content at between 200° C. and 300° C. by the same method.

Claims

1. A surface-treated heavy calcium carbonate made by treating a heavy calcium carbonate with a surface treatment agent, and satisfying the following formulae (1) to (4):
13,100≤A≤24,800  (1)
0.8≤B≤3.0  (2)
C≥0.55  (3)
0≤D1≤1000  (4) wherein: A: specific surface area measured by an air permeability method (cm.sup.2/g), B: average particle diameter (μm): 50% particle diameter of a particle measured by a laser particle size distribution analyzer (d50), C: 10% particle diameter in a particle size distribution measured by a laser particle size distribution analyzer (μm), and D1: water content measured at a temperature between 25° C. and 300° C. by a Karl-Fischer method (heating vaporization method) (ppm).

2. The surface-treated heavy calcium carbonate according to claim 1, further satisfying the following formulae (5) and (6):
E≤8  (5)
0≤D2≤150  (6) wherein: E: 90% particle diameter in a particle size distribution measured by a laser particle size distribution analyzer (μm), and D2: water content measured at a temperature between 200° C. and 300° C. by a Karl-Fischer method (heating vaporization method) (ppm).

3. The surface-treated heavy calcium carbonate according to claim 1, further satisfying the following formula (7):
8.0≤F≤9.8  (7) wherein: F: pH of an aqueous 10 wt % suspension of the surface-treated heavy calcium carbonate.

4. The surface-treated heavy calcium carbonate according to claim 1, wherein the surface treating agent is at least one selected from the group consisting of a fatty acid, its derivative and a phosphoric ester.

5. A method for producing the surface-treated heavy calcium carbonate according to claim 1, which comprises the step of: classifying heavy calcium carbonate, then heat-treating the heavy calcium carbonate at 300° C. or more to 800° C. or less by a heating apparatus selected from a kiln, an electric furnace and a microwave furnace, and surface-treating the heavy calcium carbonate by using a surface treating agent.

6. A method for producing the surface-treated heavy calcium carbonate according to claim 1, which comprises the steps of: heat-treating heavy calcium carbonate at 300° C. or more to 800° C. or less by a heating apparatus selected from a kiln, an electric furnace and a microwave furnace, then classifying the heavy calcium carbonate, and surface-treating the heavy calcium carbonate with a surface treating agent.

7. A resin composition containing the surface-treated heavy calcium carbonate according to claim 1.

8. The resin composition according to claim 7, wherein the resin is a thermoplastic resin.

9. The resin composition according to claim 8, wherein the thermoplastic resin is a polyolefin resin or a polyester resin.

10. The resin composition according to claim 9, wherein the resin composition is used for films.

11. A heavy calcium carbonate satisfying the following formulae (1) to (4):
8,800≤A≤24,800  (1)
0.8≤B≤15  (2)
0≤C1≤1000  (3)
0≤C2≤150  (4) wherein: A: specific surface area measured by an air permeability method (cm.sup.2/g), B: average particle diameter (μm): 50% particle diameter of a particle measured by a laser particle size distribution analyzer (d50), C1: water content measured at a temperature between 25° C. and 300° C. by a Karl-Fischer method (heating vaporization method) (ppm), and C2: water content measured at a temperature between 200° C. and 300° C. by a Karl-Fischer method (heating vaporization method) (ppm).

12. The heavy calcium carbonate according to claim 11, which is surface-treated by at least one surface treating agent selected from the group consisting of a fatty acid and its derivative.

13. A method for producing the heavy calcium carbonate according to claim 11, which comprises heat-treating heavy calcium carbonate at 300° C. or more to 800° C. or less by a heating apparatus selected from a kiln, an electric furnace and a microwave furnace.

14. A method for producing heavy calcium carbonate according to claim 12, which comprises surface-treating the heavy calcium carbonate after heat treatment at 300° C. or more to 800° C. or less by a heating apparatus selected from a kiln, an electric furnace and a microwave furnace.

15. A resin composition comprising a resin and the heavy calcium carbonate according to claim 11.

16. The resin composition according to claim 15, wherein the resin is a curable resin.

17. The resin composition according to claim 16, wherein the curable resin is for use in a one-component adhesive or a one-component sealant.

Description

EXAMPLES

(1) First, the present invention will be explained in more detail by way of examples according to a first present invention and comparative examples, which are, however, not intended to be limiting of the present invention. In the following explanations, the designation “parts” indicate “parts by weight”.

Example 1

(2) Commercially available heavy calcium carbonate (Super #2000, manufactured by MARUO CALCIUM CO., LTD.) was used and heat-treated using an external heating type rotary kiln (manufactured by Takasago International Corporation, external dimension Ø: 150×2000 mm) in the following conditions: external heating temperature: 580° C., number of rotations of the retort: 4 rpm, angle: 60 mm, and feed rate: 6 kg/h. At this time, the product temperature was 420° C. and the retention time was about 10 min. The product was allowed to cool and surface-treated using a Super Mixer (SMV-20, manufactured by Kawata MFG Co., Ltd.). Into a mixer was poured 5.5 kg of the product and heated, 55 g of stearic acid melted by heating to 70° C. was added with stirring in the mixer after the product temperature reached 70° C., and the mixture was further heated until the product temperature reached 130° C. with stirring. Then, a mesh with 46 μm opening was fitted to a HI-BOLTA 300-model (manufactured by TOYO HITEC CO., LTD.; non-liner) and coarse particles and coagulated particles were eliminated from the obtained product by the mesh to obtain surface-treated heavy calcium carbonate having powder properties shown in Table 1.

Example 2

(3) Commercially available heavy calcium carbonate (Super #2000, manufactured by MARUO CALCIUM CO., LTD.) was classified using a fluid classifier (Turboclassifier TC-15: registered trademark, manufactured by Nissin Engineering Inc.) in the following conditions: feed rate: 1.5 kg/h, number of rotations of a rotor: 8000 rpm, air flow rate: 1.5 m.sup.3/min, to recover the coarse powder part. This coarse powder part was heat-treated at 400° C. for 1 hr in an electric furnace. The resulting product was treated through surface treatment and screening step in the same manner as in Example 1 to obtain surface-treated heavy calcium carbonate having powder properties shown in Table 1.

Example 3

(4) Surface-treated heavy calcium carbonate having powder properties shown in Table 1 was obtained through classification, heat treatment, and surface treatment in the same manner as in Example 2 except that commercially available heavy calcium carbonate (Nanox #25A, manufactured by MARUO CALCIUM CO., LTD.) was used. In this case, the amount of the surface treating agent was 71.5 g.

Example 4

(5) Commercially available heavy calcium carbonate (Caltex 7, manufactured by MARUO CALCIUM CO., LTD.) was used to carry out heat treatment at 350° C. for 2 hr in an electric furnace. The resulting product was treated through surface treatment and screening step in the same manner as in Example 1 to obtain surface-treated heavy calcium carbonate having powder properties shown in Table 1. In this case, the amount of the surface treating agent was 82.5 g.

Example 5

(6) Commercially available heavy calcium carbonate (Caltex 5, manufactured by MARUO CALCIUM CO., LTD.) was classified using a fluid classifier (Turboclassifier TC-15) in the following conditions: feed rate: 1.0 kg/h, number of rotations of a rotor: 12000 rpm, air flow rate: 1.5 m.sup.3/min, to recover the coarse powder part. This coarse powder part was heat-treated at 400° C. for 1 hr in an electric furnace. The resulting product was treated through surface treatment and screening step in the same manner as in Example 1 to obtain surface-treated heavy calcium carbonate having powder properties shown in Table 1. In this case, the amount of the surface treating agent was 82.5 g.

Example 6

(7) Commercially available heavy calcium carbonate (Super #1500, manufactured by MARUO CALCIUM CO., LTD.) was used and heat-treated using an external heating type rotary kiln (manufactured by Takasago International Corporation, external dimension Ø: 150×2000 mm) in the following conditions: external heating temperature: 520° C., number of rotations of the retort: 4 rpm, angle: 60 mm, and feed rate: 6 kg/h. At this time, the product temperature was 380° C. and the retention time was about 10 min. The resulting product was treated through surface treatment and screening step in the same manner as in Example 1 to obtain surface-treated heavy calcium carbonate having powder properties shown in Table 1. In this case, the amount of the surface treating agent was 49.5 g.

Example 7

(8) Surface-treated heavy calcium carbonate having powder properties shown in Table 1 was obtained through heat treatment, surface treatment, and screening step in the same manner as in Example 2 except that the surface treating agent used in Example 2 was altered to trimethyl phosphate and this trimethyl phosphate was added in an amount of 27.5 g at ordinary temperature.

Example 8

(9) Surface-treated heavy calcium carbonate having powder properties shown in Table 1 was obtained through surface treating step in the same manner as in Example 1 except that that the condition of the electric furnace was altered to temperature of 750° C. and heat treating time of 1 hr to carry out heat treatment. In this case, the screening process was omitted.

Example 9

(10) Commercially available heavy calcium carbonate (Super #2000, manufactured by MARUO CALCIUM CO., LTD.) was used and heat-treated at 250° C. for 2 hr in an electric furnace. The resulting product was treated through surface treatment and screening step in the same manner as in Example 1 to obtain surface-treated heavy calcium carbonate having powder properties shown in Table 1.

Example 10

(11) Surface-treated heavy calcium carbonate having powder properties shown in Table 1 was obtained through heat treatment and screening step in the same manner as in Example 4 except that the surface treating agent used in Example 4 was altered to triethyl phosphate.

Comparative Example 1

(12) Surface-treated heavy calcium carbonate having powder properties shown in Table 2 was obtained in the same manner as in Example 1 except that the heat treatment using a rotary kiln in Example 1 was not performed.

Comparative Example 2

(13) A MC Coat S-14 (manufactured by MARUO CALCIUM CO., LTD.) which was commercially available surface-treated heavy calcium carbonate was prepared.

Comparative Example 3

(14) Surface-treated heavy calcium carbonate having powder properties shown in Table 2 was obtained through heat treatment, surface treatment, and screening step in the same manner as in Example 1 except that commercially available heavy calcium carbonate (Nanox #30, manufactured by MARUO CALCIUM CO., LTD.) was used.

Comparative Example 4

(15) Surface-treated heavy calcium carbonate having powder properties shown in Table 2 was obtained through surface treatment and screening step in the same manner as in Example 7 except that the heat treatment was not performed.

Comparative Example 5

(16) A Super S (manufactured by MARUO CALCIUM CO., LTD.) which was commercially available surface-treated heavy calcium carbonate was prepared.

Comparative Example 6

(17) Surface-treated heavy calcium carbonate having powder properties shown in Table 2 was obtained through surface treatment and screening step in the same manner as in Comparative Example 3 except that the heat treatment was not performed. In this case, the amount of the surface treating agent was 38.5 g.

(18) TABLE-US-00001 TABLE 1 Example Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 10 Specific A (cm.sup.2/g) 17,000 15,200 19,700 21,800 24,800 13,100 15,800 17,000 18,000 22,300 surface area 50% particle B (μm) 2.1 2.4 1.8 1.4 0.9 2.9 2.3 2.2 2.0 1.3 diameter 10% particle C (μm) 0.73 0.80 0.69 0.66 0.58 0.82 0.78 0.76 0.69 0.70 diameter Water content D1 (ppm) 481 218 439 558 890 302 430 281 933 870 Water content D2 (ppm) 19 9 14 58 123 27 6 4 142 111 90% particle E (μm) 4.4 4.7 3.9 2.6 2.1 7.9 4.6 4.8 4.4 2.7 diameter pH F 9.5 9.3 9.4 9.5 9.6 9.4 8.6 9.8 9.4 8.6 Residue G (ppm) 6 5 3 2 1 8 4 22 5 2 amount on a sieve Heating ratory kiln electric electric electric electric ratory kiln electric electric electric electric apparatus furnace furnace furnace furnace furnace furnace furnace furnace Heating (° C.) 420 400 400 350 400 380 750 750 250 350 temperature Surface treating stearic stearic stearic stearic stearic stearic trimethyl stearic stearic triethyl agent acid acid acid acid acid acid phosphate acid acid phosphate

(19) TABLE-US-00002 TABLE 2 Comp. Example 1 Comp. Example 2 Comp. Example 3 Comp. Example 4 Comp. Example 5 Comp. Example 6 Specific A (cm.sup.2/g) 18,500 14,100 27,100 17,400 9,000 28,000 surface area 50% particle B (μm) 2.1 3.1 1.4 2.1 9.9 1.4 diameter 10% particle C (μm) 0.68 0.85 0.60 0.71 1.25 0.56 diameter Water content D1 (ppm) 1178 894 1081 1084 1110 2105 Water content D2 (ppm) 140 123 90 155 142 390 90% particle E (μm) 4.4 8.3 3.1 4.5 23.1 3.1 diameter pH F 9.4 9.3 9.6 8.5 9.4 9.5 Residue amount G (ppm) 5 32 1 3 86 1 on a sieve Heating — — ratory kiln — — — apparatus Heating (° C.) — — 420 — — — temperature Surface treating stearic acid fatty acid stearic acid trimethyl phosphate — stearic acid agent

Examples 11 to 18, Comparative Examples 7 to 11

(20) Each surface-treated heavy calcium carbonate obtained in Examples 1 to 6, 8 and 9 and Comparative Examples 1 to 3, 5 and 6 was used, and 50 parts of polyethylene (UMERIT (registered mark) 2040F, manufactured by Ube-Maruzen Polyethylene Co., Ltd.), 50 parts of the surface-treated heavy calcium carbonate, and 1000 ppm of Irganox 1010 (registered mark) as a stabilizer were blended and these components were sufficiently mixed with stirring by a Henschel mixer to disperse these components. Then, the mixture was granulated at 220° C. by using a kneading extruder (LABO PLASTOMILL 2D25W-model, manufactured by Toyo Seiki Seisaku-Sho, Ltd.) to form a pellet. The pellet was dried at 110° C. for 3 hr and then, extruded from a T-die at 230° C. by using a film extruder (LABO PLASTOMILL D2025-model, manufactured by Toyo Seiki Seisaku-Sho, Ltd.) to obtain a non-stretched film. The non-stretched film was heated to 115° C. and stretched at a stretch ratio of 3.3 in a MD direction (extruding direction), and the stretched film was further heated to 120° C. and stretched at a stretch ratio of 3 in a TD direction (lateral direction) in a tenter stretching machine. The basic weight of this film was 15 gsm. The results of evaluation are shown in Table 3. The standard of evaluation is as follows.

(21) <Dispersibility of Particles>

(22) ⊙: visually confirmable aggregates and fisheyes caused by coarse particles are not observed in a 300 mm×300 mm film.

(23) ◯: the number of confirmable aggregates and fisheyes caused by coarse particles is 1 or 2 in a 300 mm×300 mm film.

(24) Δ: the number of confirmable aggregates and fisheyes caused by coarse particles is 3 or more and less than 10 in a 300 mm×300 mm film.

(25) x: the number of confirmable aggregates and fisheyes caused by coarse particles is 10 or more in a 300 mm×300 mm film.

(26) <Gas Mark Caused by Water>

(27) ⊙: visually confirmable air cells (gas marks) caused by volatile components such as water are not observed in a 300 mm×300 mm film.

(28) ◯: the number of confirmable air cells (gas marks) caused by volatile components such as water is 1 or 2 in a 300 mm×300 mm film.

(29) Δ: the number of confirmable air cells (gas marks) caused by volatile components such as water is 3 or more and less than 10 in a 300 mm×300 mm film.

(30) x: the number of confirmable air cells (gas marks) caused by volatile components such as water is 10 or more in a 300 mm×300 mm film.

(31) TABLE-US-00003 TABLE 3 Example or Comp. Example No. of surface- Gas mark treated heavy calcium Dispersibility caused by carbonate used of particles water Example 11 Example 1 ⊚ ⊚ Example 12 Example 2 ⊚ ⊚ Example 13 Example 3 ⊚ ⊚ Example 14 Example 4 ⊚ ◯ Example 15 Example 5 ◯ ◯ Example 16 Example 6 ◯ ⊚ Example 17 Example 8 Δ ◯ Example 18 Example 9 ◯ Δ Comp. Example 7 Comp. Example 1 ⊚ X Comp. Example 8 Comp. Example 2 X Δ Comp. Example 9 Comp. Example 3 ◯ X Comp. Comp. Example 5 X X Example 10 Comp. Comp. Example 6 Δ X Example 11

(32) As mentioned above, the surface-treated heavy calcium carbonate according to a first present invention is reduced on cost, has high dispersibility and can provide a film superior in surface characteristics. It is noted that Example 17 has a high pH and is therefore unsuitable for sanitary materials such as paper diapers, body fluid absorbing pads and bed sheets.

Examples 19 to 20, Comparative Examples 12 to 13

(33) Each surface-treated heavy calcium carbonate obtained in Examples 7 and 10 and Comparative Examples 4 and 5 was used. Sufficiently mixed were 60 parts of polyethylene terephthalate (PET) (manufactured by QUADRANT POLYPENCO JAPAN LTD., specific gravity: 1.39) and 40 parts of the surface-treated heavy calcium carbonate with stirring by a Henschel mixer to sufficiently disperse these components. Then, the mixture was granulated at 280° C. by using a kneading extruder (LABO PLASTOMILL 2D25W-model, manufactured by Toyo Seiki Seisaku-Sho, Ltd.) to form a pellet. The pellet was dried at 110° C. for 1 hr, then, extruded in a sheet-like form from a T-die at 290° C. by using a film extruder (LABO PLASTOMILL D2025-model, manufactured by Toyo Seiki Seisaku-Sho, Ltd.), and cooled to solidify in a 30° C. cooling drum to obtain a non-stretched film. The non-stretched film was heated to 95° C. and stretched at a stretch ratio of 3.3 in a MD direction (extruding direction), and the stretched film was further heated to 120° C. and stretched at a stretch ratio of 3 in a TD direction (lateral direction) in a tenter stretching machine to obtain a film 50 μm in thickness. The results of evaluation are shown in Table 4.

(34) <IV (Melt Viscosity) of the Pellet>

(35) The IV (melt viscosity) of a simple PET resin at 280° C. was defined as 100 and indexation of the IV of the obtained pellet was made as an indicator of molecular weight. It is considered that the resin is more hydrolyzed with decrease in the indexed value.

(36) <Dispersibility of Particles>

(37) ⊙: visually confirmable aggregates and fisheyes caused by coarse particles are not observed in a 300 mm×300 mm film.

(38) ◯: the number of confirmable aggregates and fisheyes caused by coarse particles is 1 or 2 in a 300 mm×300 mm film.

(39) Δ: the number of confirmable aggregates and fisheyes caused by coarse particles is 3 or more and less than 10 in a 300 mm×300 mm film.

(40) x: the number of confirmable aggregates and fisheyes caused by coarse particles is 10 or more in a 300 mm×300 mm film.

(41) <Gas Mark Caused by Water>

(42) ⊙: visually confirmable air cells (gas marks) caused by volatile components such as water are not observed in a 300 mm×300 mm film.

(43) ◯: the number of confirmable air cells (gas marks) caused by volatile components such as water is 1 or 2 in a 300 mm×300 mm film.

(44) Δ: the number of confirmable air cells (gas marks) caused by volatile components such as water is 3 or more and less than 10 in a 300 mm×300 mm film.

(45) x: the number of confirmable air cells (gas marks) caused by volatile components such as water is 10 or more in a 300 mm×300 mm film.

Examples 21 and 22, Comparative Examples 14 and 15

(46) Each surface-treated heavy calcium carbonate obtained in Examples 7 and 10 and Comparative Examples 4 and 6 was used. Sufficiently mixed were 70 parts of a bioplastic (TERRAMAC TP-4000 (registered mark), manufactured by UNITIKA LTD, specific gravity: 1.25) and 30 parts of the surface-treated heavy calcium carbonate with stirring by a Henschel mixer to sufficiently disperse these components. Then, the mixture was granulated at 180° C. by using a kneading extruder (LABO PLASTOMILL 2D25W-model, manufactured by Toyo Seiki Seisaku-Sho) to form a pellet. The pellet was dried at 110° C. for 1 hr, then, extruded in a sheet-like form from a T-die at 190° C. by using a film extruder (LABO PLASTOMILL D2025-model, manufactured by Toyo Seiki Seisaku-Sho) to obtain a non-stretched film 100 μm in thickness. The results of evaluation are shown in Table 4.

(47) <IV of the Pellet (Melt Viscosity)>

(48) The IV (melt viscosity) of a simple bioplastic resin at 190° C. was defined as 100 and indexation of the IV of the obtained pellet was made as an indicator of molecular weight. It is considered that the resin is more hydrolyzed with decrease in the indexed value.

(49) <Dispersibility of Particles>

(50) ⊙: visually confirmable fisheyes caused by coagulates and coarse particles are not observed in a 100 mm×200 mm film.

(51) ◯: the number of confirmable fisheyes caused by coagulates and coarse particles is 1 or 2 in a 100 mm×200 mm film.

(52) Δ: the number of confirmable fisheyes caused by coagulates and coarse particles is 3 or more and less than 10 in a 100 mm×200 mm film.

(53) x: the number of confirmable fisheyes caused by coagulates and coarse particles is 10 or more in a 100 mm×200 mm film.

(54) <Gas Mark Caused by Water>

(55) ⊙: visually confirmable holes (gas marks) caused by volatile components such as water are not observed in a 100 mm×200 mm film.

(56) ◯: the number of confirmable holes (gas marks) caused by volatile components such as water is 1 or 2 in a 100 mm×200 mm film.

(57) Δ: the number of confirmable holes (gas marks) caused by volatile components such as water is 3 or more and less than 10 in a 100 mm×200 mm film.

(58) x: the number of confirmable holes (gas marks) caused by volatile components such as water is 10 or more in a 100 mm×200 mm film.

(59) TABLE-US-00004 TABLE 4 Example or Comp. Example No. of IV surface-treated index Gas mark heavy calcium of Dispersibility caused by carbonate used pellets of particles water Example 19 Example 7 103 ⊚ ⊚ Example 20 Example 10 105 ⊚ ◯ Comp. Comp. Example 4 89 ◯ X Example 12 Comp. Comp. Example 5 98 X Δ Example 13 Example 21 Example 7 106 ⊚ ⊚ Example 22 Example 10 107 ◯ ⊚ Comp. Comp. Example 4 95 ◯ X Example 14 Comp. Comp. Example 6 82 Δ X Example 15

(60) As mentioned above, the surface-treated heavy calcium carbonate according to a first present invention has low water content and therefore can stably provide a film reduced in fisheyes and gas marks even if the resin is a polyester resin which is easily reduced in molecular weight by hydrolysis.

(61) Next, the present invention will be explained in more detail by way of examples according to a second present invention and comparative examples, which are, however, not intended to be limiting of the present invention. In the following explanations, the designation “part(s)” indicates “part(s) by weight”.

Example 1

(62) Commercially available heavy calcium carbonate (Super S, manufactured by MARUO CALCIUM CO., LTD.) was used and heat-treated using an external heating type rotary kiln (manufactured by Takasago International Corporation, external dimension Ø: 150×2000 mm) in the following conditions: external heating temperature: 62° C., number of rotations of the retort: 4 rpm, angle: 60 mm, and feed rate: 6 kg/h. At this time, the product temperature was 490° C. and the retention time was about 10 min. This particle product was allowed to cool. Then, a mesh with 75 μm opening was fitted to a HI-BOLTA 300-model (manufactured by TOYO HITEC CO., LTD.; non-liner) and coarse particles and coagulated particles were eliminated from the particle product by the mesh to obtain heavy calcium carbonate having powder properties shown in Table 1A.

Example 2

(63) Heat treatment was performed in the same manner as in Example 1 except that commercially available heavy calcium carbonate (Super SS, manufactured by MARUO CALCIUM CO., LTD.) was used. The product was allowed to cool and surface-treated using a Super Mixer (SMV-20, manufactured by Kawata MFG Co., Ltd.). Poured was 6 kg of the product into a mixer and heated. After the product temperature reached 70° C., 48 g of tallow fatty acid ester was added with stirring and further heated with stirring until the product temperature reached 130° C. Then, the resulting product was treated through a screening step in the same manner as in Example 1 to obtain surface-treated heavy calcium carbonate having powder properties shown in Table 1A.

Example 3

(64) Commercially available heavy calcium carbonate (Super SSS, manufactured by MARUO CALCIUM CO., LTD.) was used and heat-treated at 400° C. for 1 hr in an electric furnace. The product was treated through a screening step in the same manner as in Example 1 to obtain heavy calcium carbonate having powder properties shown in Table 1A.

Example 4

(65) Commercially available heavy calcium carbonate (Super SSS, manufactured by MARUO CALCIUM CO., LTD.) was heat-treated in the same manner as in Example 3 and surface-treated in the same manner as in Example 2. The product was treated through a screening step in the same manner as in Example 1 to obtain surface-treated heavy calcium carbonate having powder properties shown in Table 1A. In this case, the surface treating agent was stearic acid and was poured into the reaction system after melted at 70° C. The amount of the surface treating agent was 36 g.

Example 5

(66) Surface-treated heavy calcium carbonate having powder properties shown in Table 1A was obtained through heat treatment, surface treatment, and screening step in the same manner as in Example 4 except that commercially available heavy calcium carbonate (Super #1700, manufactured by MARUO CALCIUM CO., LTD.) was used. In this case, the surface treating agent was butyl stearate and its amount was 60 g.

Example 6

(67) Surface-treated heavy calcium carbonate having powder properties shown in Table 1A was obtained through heat treatment, surface treatment, and screening step in the same manner as in Example 4 except that commercially available heavy calcium carbonate (Super #2000, manufactured by MARUO CALCIUM CO., LTD.) was used. In this case, the amount of stearic acid which was the surface treating agent was 60 g.

Example 7

(68) Surface-treated heavy calcium carbonate having powder properties shown in Table 1A was obtained through surface treating and screening step in the same manner as in Example 6 except that the condition of the electric furnace was altered to temperature of 250° C. and heat treating time of 1 hr.

Example 8

(69) Commercially available heavy calcium carbonate (Caltex 5, manufactured by MARUO CALCIUM CO., LTD.) was classified using a fluid classifier (Turboclassifier TC-15) in the following conditions: feed rate: 1.0 kg/h, number of rotations of a rotor: 1.2000 rpm, air flow rate: 1.5 m.sup.3/min, to recover the coarse powder part. This coarse powder part was heat-treated at 400° C. for 1 hr in an electric furnace. The resulting product was treated through surface treatment and screening step in the same manner as in Example 6 to obtain surface-treated heavy calcium carbonate having powder properties shown in Table 1A. In this case, the amount of stearic acid which was the surface treating agent was 82.5 g.

Comparative Example 1

(70) Commercially available heavy calcium carbonate (N-35, manufactured by MARUO CALCIUM CO., LTD.).

Comparative Example 2

(71) Commercially available heavy calcium carbonate (Super S, manufactured by MARUO CALCIUM CO., LTD.).

Comparative Example 3

(72) Commercially available surface-treated heavy calcium carbonate (MC Coat S-13, manufactured by MARUO CALCIUM CO., LTD.).

Comparative Example 4

(73) Commercially available surface-treated heavy calcium carbonate (MC Coat S-20, manufactured by MARUO CALCIUM CO., LTD.).

Comparative Example 5

(74) Surface-treated heavy calcium carbonate having powder properties shown in Table 1A by surface treating through a screening step in the same manner as in Example 8 except that the classification was not performed.

(75) TABLE-US-00005 TABLE 1A Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Specific A (cm.sup.2/g) 8,800 9,800 12,500 10,900 16,500 17,000 18,000 24,800 surface area 50% particle B (μm) 9.9 5 4.2 4.2 2.4 2.1 2.0 0.9 diameter Water content C1 (ppm) 543 466 910 275 780 481 933 890 Water content C2 (ppm) 33 46 49 11 18 19 142 95 Surface treating none tallow fatty none stearic acid butyl stearic acid stearic acid stearic acid agent acid ester stearate Comp. Comp. Comp. Comp. Comp. Example 1 Example 2 Example 3 Example 4 Example 5 Specific A (cm.sup.2/g) 3,900 9,000 11,600 18,500 28,200 surface area 50% particle B (μm) 22.4 9.9 4.2 2.1 0.8 diameter Water content C1 (ppm) 534 1110 1220 1345 1211 Water content C2 (ppm) 97 124 110 140 108 Surface treating agent none none fatty acid fatty acid fatty acid

Examples 9 to 16, Comparative Examples 6 to 10

(76) Each heavy calcium carbonate obtained in Examples 1 to 8 and Comparative Examples 1 to 5 was used and each synthetic resin composition was produced in the following manner to conduct a storage stability test. The test results are shown in Table 2A.

(77) In this case, the heavy calcium carbonate was not pre-dried though silica was pre-dried at 11.0° C. for 3 hr in an oven.

(78) (Polyurethane One-Component Adhesive)

(79) L-1036:540 parts, manufactured by Mitsui Takeda Chemicals Inc., (polyurethane resin)

(80) Mineral spirit: 60 parts (solvent)

(81) Aerosil 200: 2.4 parts, manufactured by Degussa Japan Co., Ltd., (silica)

(82) Heavy calcium carbonate: 400 parts

(83) <Storage Stability Test>

(84) The above formulation ingredients were mixed with stirring by using a Dalton universal mixing and stirring machine (manufactured by Dalton Co., Ltd.: 2 L) to obtain a synthetic resin composition. This composition was filled in a cartridge and its viscosity (2 rpm: V1 and 20 rpm: V2) and TI value (TI.sub.23 value: V1/V2) were measured just after it was left at 23° C. for one day. Then, its viscosity (2 rpm: V3 and 20 rpm: V4) and TI value (TI.sub.70 value: V3/V4) were measured just after it was left at 70° C. for one day, and further, the rate of change in viscosity (2 rpm: V3/V1×100, 20 rpm: V4/V2×100) was measured to evaluate storage stability.

(85) <Appearance of a Coating>

(86) Also, a synthetic resin composition prepared by mixing the above formulation gradients with stirring was taken and spread into a thin film 1 mm in thickness on a straight plate to rate the appearance of the film visually according to the following criteria.

(87) ◯: the coating surface is uniform and no aggregate is observed.

(88) Δ: though the coating surface is uniform, several aggregates are confirmed.

(89) x: the coating surface is not uniform and many aggregates are confirmed.

(90) <Sedimentation Test>

(91) A synthetic resin composition prepared by mixing the above formulation gradients with stirring was poured into a transparent mayonnaise jar and allowed to stand at 70° C. for 7 days in a constant temperature and humidity testing chamber. Then, the resin composition was visually observed to rate according to the following criteria.

(92) ◯: no precipitate is observed at all or slight precipitates are observed on the bottom of the jar.

(93) Δ: though a thin deposit is observed on the bottom of the jar, the composition can be used without any problem.

(94) x: a hard cake is formed on the bottom of the jar.

(95) TABLE-US-00006 TABLE 2A Example or Comp. Example No. of surface- Viscosity after at Viscosity after at treated 23° C. for one day 70° C. for one day Rate of change calcium 2 rpm 20 rpm 2 rpm 20 rpm in viscosity carbonate (Pa .Math. s) (Pa .Math. s) TI.sub.23 value (Pa .Math. s) (Pa .Math. s) TI.sub.70 value 2 rpm (%) 20 rpm (%) Appearance Sedimentation used V1 V2 V1 /V2 V3 V4 V3/V4 V3/V1 × 100 V4/V2 × 100 of coating test Example 9 Example 1 31 17 1.82 43 24 1.79 139 141 ◯ Δ Example 10 Example 2 40 25 1.60 52 33 1.58 130 132 ◯ Δ Example 11 Example 3 39 21 1.86 60 36 1.67 154 171 ◯ ◯ Example 12 Example 4 53 20 2.65 75 32 2.34 142 160 ◯ ◯ Example 13 Example 5 54 22 2.45 84 35 2.40 156 159 ◯ ◯ Example 14 Example 6 98 28 3.50 147 45 3.27 150 161 ◯ ◯ Example 15 Example 7 122 46 2.65 211 88 2.40 173 191 Δ ◯ Example 16 Example 8 132 41 3.22 244 91 2.68 185 222 Δ ◯ Comp. Comp. 29 17 1.71 51 28 1.82 176 165 ◯ X Example 6 Example 1 Comp. Comp. 33 18 1.83 121 81 1.49 367 450 ◯ Δ Example 7 Example 2 Comp. Comp. 62 29 2.14 195 115 1.70 315 397 Δ ◯ Example 8 Example 3 Comp. Comp. 84 26 3.23 806 277 2.91 960 1065 X ◯ Example 9 Example 4 Comp. Comp. 132 36 3.67 2,350 655 3.59 1780 1819 X ◯ Example 10 Example 5

(96) As mentioned above, the heavy calcium carbonate according to the second aspect of the present invention has high storage stability even if the preliminary drying step is omitted and therefore can provide an adhesive maintaining thixotropy.

Examples 17 to 24, Comparative Examples 11 to 15

(97) Each heavy calcium carbonate obtained in Examples 1 to 8 and Comparative Examples 1 to 5 was used and each synthetic resin composition was produced in the following manner to conduct a storage stability test. The test results are shown in Table 3A.

(98) In this case, the heavy calcium carbonate was not pre-dried though silica was pre-dried at 110° C. for 3 hr in an oven.

(99) (Modified Silicone One-Component Sealant)

(100) MS polymer 203: 540 parts, manufactured by Kaneka Corporation (modified silicone resin)

(101) DINP: 30 parts, manufactured by J-PLUS Co., Ltd. (solvent)

(102) Aerosil 200: 8 parts, manufactured by Degussa Japan Co., Ltd., (silica)

(103) KBM1003: 3 parts, manufactured by Shin-Etsu Chemical Co., Ltd. (dehydrating agent)

(104) NEOSTAN U-220H: 1 part, manufactured by NITTO KASEI CO., LTD. (tin catalyst)

(105) KBM-603: 1 part, manufactured by Shin-Etsu Chemical Co., Ltd. (adhesive promoter)

(106) Heavy calcium carbonate: 100 parts

(107) <Storage Stability Test>

(108) The above formulation ingredients were mixed with stirring by using a Dalton universal mixing and stirring machine (manufactured by Dalton Co., Ltd.: 2 L) to obtain a synthetic resin composition. This composition was filled in a cartridge and its viscosity (1 rpm: V1 and 10 rpm: V2) and TI value (TI.sub.23 value: V1/V2) were measured just after it was left at 23° C. for one day. Then, its viscosity (1 rpm: V3 and 10 rpm: V4) and TI value (TI.sub.50 value: V3/V4) were measured just after it was left at 50° C. for 7 days and further, the rate of change in viscosity (1 rpm: V3/V1×100, 10 rpm: V4/V2×100) was measured to evaluate storage stability.

(109) <Dispersibility Test>

(110) Also, a synthetic resin composition prepared by mixing the above formulation gradients with stirring was taken and spread so as to form a thin film having a length of 5 cm or more, a width of 5 cm or more, and a thickness of 1 mm or less on a glass plate by a spatula. The appearance of the film was visually rated according to the following criteria.

(111) ◯: any aggregate having a size of 0.5 mm or more is not observed on a 5-em square coating surface.

(112) Δ: 1 or 2 aggregates having a size of 0.5 mm or more are observed on a 5-cm square coating surface.

(113) x: 3 or more aggregates having a size of 0.5 mm or more are observed on a 5 cm square coating surface.

(114) TABLE-US-00007 TABLE 3A Example or Comp. Viscosity after at Viscosity after at Example No of 23° C. for one day 50° C. for 7 days Rate of change surface treated 1 rpm 1 rpm 10 rpm in viscosity calcium carbonate (pa .Math. s) 10 rpm (Pa .Math. s) TI.sub.23 value (Pa .Math. s) (Pa .Math. s) TI.sub.50 value 1 rpm (%) 10 rpm (%) used V1 V2 V1/V2 V3 V4 V3/V4 V3/V1 × 100 V4/V2 × 100 Dispersibility Example 17 Example 1 2240 325 6.89 2680 401 6.68 120 123 ◯ Example 18 Example 2 2390 350 6.83 2730 406 6.72 114 116 ◯ Example 19 Example 3 2350 338 6.95 2810 422 6.66 120 125 ◯ Example 20 Example 4 2410 345 6.99 2730 410 6.66 113 119 ◯ Example 21 Example 5 2860 403 7.10 3120 470 6.64 109 117 ◯ Example 22 Example 6 2760 392 7.04 3220 478 6.74 117 122 ◯ Example 23 Example 7 2810 403 6.97 3330 505 6.59 119 125 Δ Example 24 Example 8 3040 424 7.17 3590 531 6.76 118 125 Δ Comp. Comp. Example 1 1570 240 6.54 2090 356 5.87 133 148 ◯ Example 11 Comp. comp. Example 2 2290 333 6.88 3210 515 6.23 140 155 ◯ Example 12 Comp. Comp. Example 3 2390 345 6.93 3290 517 6.36 138 150 ◯ Example 13 Comp. Comp. Example 4 2910 423 6.88 3830 672 5.70 132 159 Δ Example 14 Comp. Comp. Example 5 3140 444 7.07 4420 745 5.93 141 168 X Example 15

(115) As mentioned above, the heavy calcium carbonate according to a second present invention can provide a sealant superior in storage stability even if the preliminary drying step is omitted.

INDUSTRIAL APPLICABILITY

(116) As mentioned above, the surface-treated heavy calcium carbonate according to a first present invention can be produced in a dry system and therefore has advantages on cost. There is therefore provided surface-treated heavy calcium carbonate which is suitable for the production of a porous film exactly controlled in its pore diameter and can be sufficiently dehydrated either without any pre-drying treatment or by simple pre-drying treatment because it exhibits excellent dispersibility and low-water characteristic as a filler when it is compounded in, for example, a film forming resin.

(117) Also, the surface-treated heavy calcium carbonate according to a first present invention has low water characteristic and is therefore suitable for easily hydrolyzable polyester resins such as bioplastics, PET and PEN, and also for resins called engineering plastics such as nylon and polycarbonate which have so high glass transition temperature that they must be kneaded at a high temperature, showing its excellently large usability.

(118) The heavy calcium carbonate according to a second present invention can be produced in a dry system and therefore has advantages on cost. There is therefore provided surface-treated heavy calcium carbonate which can be sufficiently dehydrated either withouts any pre-drying treatment or by simple pre-drying treatment when it is compounded in a curable resin such as a one-component type moisture curable adhesive or sealant.

(119) Also, the heavy calcium carbonate according to a second present invention has low water characteristic and is therefore suitable for bioplastics, easily hydrolyzable polyester resins such as PET and PEN and also for resins called engineering plastics such as nylon and polycarbonate which have so high glass transition temperature that they must be kneaded at a high temperature, showing its excellently large usability.