JP2006117891A - Thermoplastic resin-based sliding material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin-based sliding material having higher lubricity (lower frictionality) than the raw material thereof and causing no increase of wearing properties, by mixing a crystalline thermoplastic resin with an add-in material usable as a reinforcing material and a nucleating agent of the resin. <P>SOLUTION: This thermoplastic resin-based sliding material is obtained by containing, in a self-lubricating crystalline thermoplastic resin, one or more add-in materials usable as the reinforcing material and the nucleating material thereof, and having a sliding surface of smaller friction coefficient by ≥10% measured by a journal tester than the crystalline thermoplastic resin and a larger flexural strength than the raw material crystalline thermoplastic resin by ≥5% measured by JIS K7171, so as to have a higher lubricity (lower frictionality) than the raw material crystalline thermoplastic resin thereof without causing increase of wearing properties and to be enabled to slide stably, safely and accurately. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

In the present invention, the molding process from the crystalline thermoplastic resin and the molded body are controlled by the additive material having the functions of the reinforcing material and the crystal core material, and high lubricity (
The present invention relates to a thermoplastic resin-based sliding material having low friction) and high wear resistance.

Many self-lubricating materials can be used as solid lubricants, layered inorganic compounds (molybdenum disulfide, graphite, boron nitride, etc.), soft metal coatings, wear-resistant alloys, metal plating (gold, palladium) , Tin plating)
Ceramics, sintered alloys, self-lubricating thermoplastic resins and thermosetting resins are known as typical solid lubricants.
Note that it is impossible to predict the specific behavior of the sliding surface of the solid lubricant from the model that explains the behavior of friction and wear that occurs between the solid lubricant and the contact material. Only the suitability of use is determined by experiments (see, for example, Non-Patent Document 1).

The solid lubricant lubrication system includes a sliding system in which solid lubricant powder is interposed on the sliding surface (see the explanatory diagram of FIG. 3), and a sliding surface in which lubricating oil containing solid lubricant powder is interposed on the sliding surface. Dynamic method (refer to the explanatory diagram in Fig. 4), sliding method (see the explanatory diagram in Fig. 5) with a soft metal provided on a hard metal such as steel, and a sliding surface embedded with solid lubricant The sliding method used (see the explanatory diagram in FIG. 6), the sliding method in which the sliding surface is provided with a friction surface of solid lubricant (see the explanatory diagram in FIG. 7), and the sliding member is formed from a self-lubricating material There is a method to do.
As self-lubricating thermoplastic resins, it is known that polytetrafluoroethylene resins (hereinafter sometimes referred to as PTFE resins), crystalline olefin resins, polyamide resins, polyester resins, and the like can be solid lubricants. ing.
However, it is well known that in a wear progress test of a resin bearing using a self-lubricating thermoplastic resin or the like, the wear progress curve shown in FIG.

The Lubrication Society of Japan: “Tribology of New Materials” published by Yokendo Co., Ltd., 1991

FIG. 8 is an explanatory view showing the results of a wear progression test of a synthetic resin bearing,
The wear indicated by symbol A represents a general wear progress curve of a synthetic bearing made of a self-lubricating resin, and the wear progresses higher at the initial wear (0−H ₁ ), and then the steady region (H ₁ − In H ₃ ), wear progresses at a constant and moderate rate.
The wear indicated by symbol B is a wear progress curve in which there is no initial wear, and is often seen in abrasive wear and virginity. The wear indicated by symbol C is the initial region (0
It is often observed when the effect of the friction material acts on -H ₂ ), and then the surface roughness increases due to damage of the mating shaft, etc., and wear progresses while acting as abrasive grains at the sliding interface. Is a curved line.
It is generally known that self-lubricating thermoplastic resin bearings also have wear progress curves indicated by reference signs A and B. When filler particles are present, the sliding surface is abrasive. It is well known that wear tends to occur and shows a tendency to show the progress of wear as indicated by symbol B in FIG.

With respect to the conventional sliding material of a self-lubricating thermoplastic resin (for example, polyethylene or the like), the following problems (A) to (D) existed.
(B) The sliding surface is easily worn by the use over time, the sliding becomes unstable, and there is a problem that the life of the sliding material is short.
(B) When a filler such as an inorganic compound is mixed in a self-lubricating thermoplastic resin,
There has been a problem that the amount of wear due to use over time has significantly increased.
(C) From a self-lubricating thermoplastic resin, it is difficult (substantially impossible) to satisfy the basic conditions of a sliding material such as high lubricity (low friction coefficient) and wear resistance. There was a problem.
(D) Conventionally, it is known that even when a filler such as an inorganic compound and a crystal nucleus material are blended with a thermoplastic resin, the wear property becomes the behavior of symbol B in FIG. See).

Therefore, many studies by the present inventor have been conducted mainly,
Additives that function as a reinforcing material and crystal nucleus material for the target resin and satisfy special conditions (see the conditions of (a) and (b) of the additive below) In the present invention, it is found in the present invention that when mixed into a lubricious crystalline thermoplastic resin, a structure having high lubricity (low friction) and high wear resistance is obtained in cooling and solidification from the raw material hot melt. It was done.
(A) The present invention has a higher lubricity than the thermoplastic resin,
And it aims at providing the thermoplastic resin-type sliding material which is excellent also in abrasion resistance.
(B) Another object of the present invention is to provide a thermoplastic resin-based sliding material having both excellent wear resistance, high lubricity and mechanical properties.
(C) Another object of the present invention is to provide a thermoplastic resin-based sliding material that is excellent in industrial feasibility from the viewpoint of manufacturing cost and manufacturing technology.
(D) Another object of the present invention is to provide a thermoplastic resin-based sliding material that can be easily molded into a desired shape.
(E) Another object of the present invention is to provide a thermoplastic resin-based sliding material that can be stably, safely, and accurately slid even when used for a long time.

The thermoplastic resin-based sliding material according to the present invention includes one or a plurality of additives that can be used as a reinforcing material and a crystal nucleus material in a self-lubricating crystalline thermoplastic resin,
It has a sliding surface whose friction coefficient measured by a journal testing machine is 10% or less smaller than that of the crystalline thermoplastic resin, and its bending strength (MPa) measured by JISK7171 is 5% or more than that of the crystalline thermoplastic resin. Big,
It is characterized by.

According to the present invention, various effects represented by the following (a) to (e) can be obtained.
(A) A thermoplastic resin-based sliding material that is excellent in mechanical strength, has improved lubricity as compared with a thermoplastic resin, and does not increase in wear over time is provided.
That is, there is provided a thermoplastic resin-based sliding material having a characteristic that the amount of wear that is not found in conventional thermoplastic resin-based sliding materials does not increase with time (characteristics not found in the past).
(B) A thermoplastic resin-based sliding material with significantly improved lubricity and mechanical properties is provided.
(C) A thermoplastic resin-based sliding material excellent in industrial feasibility is also provided from the manufacturing cost and manufacturing technology.
(D) A thermoplastic resin-based sliding material that has both high lubricity and high wear resistance and can be easily molded into a desired shape is provided.
(E) A thermoplastic resin-based sliding material capable of stable, accurate and safe sliding even after long-term use is provided.

<Outline of the present invention>
The thermoplastic resin-based sliding material of the present invention (hereinafter sometimes abbreviated as a sliding material) is a crystalline thermoplastic resin (hereinafter, referred to as an additive material having both functions of a reinforcing material and a crystal nucleus material). (Sometimes called molding raw materials), a structure with excellent lubricity and wear resistance is formed by the function of the crystal core material when it is melted and cooled / solidified, and it is structured by the function of the reinforcing material. Mechanical properties (particularly mechanical strength) suitable for the sliding material are imparted to the body. In other words, the sliding material according to the present invention has high wear resistance that exhibits the wear progress behavior shown by the symbol A in FIG. 8 regardless of the presence of the additive (see Examples below).

<Crystalline thermoplastic resin>:
The crystalline thermoplastic resin is a resin that can be molded into a structure defined by the present invention by mixing an additive having both functions of a reinforcing material and a crystal nucleus material. Use of crystalline olefin resin (typically polyethylene and polypropylene), polyamide resin (typically nylon 6, nylon 66 and nylon 46), polyester resin (polybutylene terephthalate, polyethylene terephthalate, etc.), polyacetal resin, etc. Can be used alone or in different combinations (for example,
A combination of high density polyethylene and polypropylene) may be used. Further, a combination of a plurality of types within the same type (for example, a combination of high density polyethylene and medium density polyethylene) may be used.
However, the sliding material of the present invention can be used with one or a combination of a crystalline olefin resin alone or a crystalline olefin resin and a smaller amount of polyamide resin / polyacetal resin. It is easy to make a sliding material of a structure having wear resistance.

<Crystalline olefin resin>:
As long as the polyethylene has a strength capable of becoming a structure of a sliding material, both a homopolymer and a copolymer can be the subject of the present invention. Polyethylene is generally treated as a homopolymer even if it contains a small amount of a copolymer, and the same applies to the present invention. Polyethylene exists from a high density of about 0.94 g / cm ³ to a very low density, but it can be formed into a sliding material containing the additive of the present invention and has strength to withstand use. High density, medium density, low density, linear low density and linear low density polyethylene can be used.
High-density polyethylene has, for example, a density of about 0.941 to about 0.965 g / cm ³ and a wide molecular weight distribution.
Through the solidification process, high mechanical strength, high lubricity and high wear resistance (especially
It is suitable to make a sliding material of a structure having a prevention of an increase in the amount of wear when sliding for a long time).
In some cases, the mechanical strength of the polyethylene copolymer is improved by increasing the degree of crystallinity (for example, the comonomer is 1-butene or the like), which is useful as a structure for a sliding material. Polyethylene copolymers are generally
A copolymer with an alpha-olefin other than ethylene is suitable for the sliding material in terms of strength.
Even if polyethylene is a polyethylene to which a crystal nucleating agent has been added in advance,
By incorporating the additive of the present invention, a sliding material that enjoys the effects of the present invention can be obtained. The same applies to crystalline thermoplastic resins other than polyethylene.

Polypropylene can be produced by any polymerization method, and either a homopolymer or a copolymer is an object of the present invention. Examples of the comonomer of the copolymer include ethylene, 1-butene, 1-pentene,
4-methyl-1-pentene, 1-hexene, 4-methyl-1,4-hexadiene, pentene, 1-octene, 1-dodecene, 1-hexadecene, 1-tetradecene and the like. If the high stereoregularity, for example, the isotactic pendant fraction (the isotactic fraction in the pentad unit in the polypropylene molecular chain) is high stereoregularity of 0.97 or more, the structure of the structure for a sliding material Characteristics can be improved.
Polypropylene is generally added with a crystal nucleating agent,
The effect of the present invention can be produced regardless of whether the crystal nucleating agent is added or not added.

<Polyamide resin>:
As the polyamide resin, those produced by any method of ring-opening polymerization of lactams and polycondensation of diamine and dicarboxylic acid can be used. Nylon 6 and nylon 66 are suitable from the viewpoint of the characteristics of the structure for sliding material.

<Polyacetal resin>:
As the polyacetal resin, either a homopolymer of formaldehyde or a copolymer thereof (for example, a copolymer with ethylene oxide) can be used.

<Polyester resin>:
As the polyester resin, any of polyethylene terephthalate and polybutylene terephthalate can be used, and those suitable for the characteristics required for the sliding material are used.

<Additives>:
As the additive, those satisfying the following conditions (a) and (b) (hereinafter, sometimes referred to as the conditions (a) and (b) of the additive) are used.
(A) the condition that the target crystalline thermoplastic resin has both functions of a reinforcing material and a crystal nucleating agent;
(B) A structure having a sliding surface with a coefficient of friction that is 10% or more smaller than that of the target crystalline thermoplastic resin and a bending strength value (MPa) that is 5% or more larger (that is,
It is a condition of giving to a molded object).
The friction coefficient of the condition (b) for the additive is higher than that of crystalline thermoplastic resin.
It should be 10% or less, and it is technically difficult to reduce it by 80% or more.
In addition, if the friction coefficient is about 20 to 70% smaller than that of the crystalline thermoplastic resin, it is possible to remarkably improve the wear resistance (see Examples described later).
Further, the condition that the structure (molded body) is given a bending strength value (MPa) that is 5% or more larger than that of the crystalline thermoplastic resin under the condition (b) of the additive,
The upper limit is about 350% higher than that of crystalline thermoplastic resin. However, if an additive is added in an amount that allows higher bending strength (MPa), high lubricity (low friction) and high resistance are achieved. It becomes difficult to maintain a balance between wear and high mechanical properties.
Reinforcing materials are substances added to thermoplastic resins for the purpose of improving / improving various properties or properties and reducing costs. Crystal nucleating agents affect the formation and crystal structure of crystalline thermoplastic resins. It is a substance added for the purpose of giving

Many compounds of inorganic, organic, metal, and metal oxide types having various shapes such as powder, fiber, and needle are known as reinforcing materials for thermoplastic resins.・ Many organic and polymer compounds
It is known as a crystal nucleating agent for thermoplastic resins.
However, in the present invention, the functions of the thermoplastic resin as a reinforcing material and a crystal nucleus material are used in combination, and the additives (i) and (b) corresponding to the target crystalline thermoplastic resin. A compound having a type, shape, or the like that satisfies the above conditions can be used as an additive.

For example, alkaline earth metal oxides, carbonates and sulfates have both functions as thermoplastic resin reinforcing materials and crystal nucleating agents. In the present invention, these additives (i) and (b) It is necessary to satisfy these conditions. Therefore, these oxides, carbonates, and sulfates are subjected to modification and modification treatments so as to satisfy the conditions (a) and (b) of the additive and are used for the present invention.
The alkaline earth metal carbonate is whisker-like calcium carbonate having an aspect ratio of 3 to 100 represented by the ratio of the major axis to the minor axis (see Examples below). The whisker-like calcium carbonate can enjoy the effects of the present invention as long as the whisker is similar or similar to the whisker. Therefore, it may be a calcium carbonate whisker (that is, a growth product of a single crystal of calcium carbonate) or a calcium carbonate having a shape similar to or similar to a whisker.
In addition, aspect ratios of 3 to 100 such as whisker-like calcium carbonate are easily visible with a scanning electron microscope at a magnification of about 1000 times.
Also, for example, talc, clay, kaolin, inorganic oxides other than alkaline earth metals, inorganic phosphates and silicates, and metal salts (for example, potassium titanate) are also used as thermoplastic resin reinforcements and crystal nucleating agents. Because it functions as
It can be used by satisfying the conditions (b) and (b) of the additive.

Regarding crystal nucleating materials, many inorganic, organic, and polymeric compound crystal nucleating agents are known, and organic sorbitol-based crystal nucleating agents are generally used because of their high performance. Is used in an amount of less than 0.5% by weight (less than 1% by weight at most) based on the resin weight. Inorganic crystal nucleating agents are also generally used in an amount of less than 1% by weight based on the resin weight.

One or more additives can be used. For crystalline olefin resins (particularly polyethylene and polypropylene), the effect of the present invention is maximized when whisker-like calcium carbonate is added as an additive. (See the examples below).
The compounding amount of the additive is smaller than the general compounding amount as the reinforcing material, and is larger than the general compounding amount as the crystal nucleus material. The compounding amount of the additive is, for example, 0.8 to 40% by weight (preferably based on the total weight)
0.8-30% by weight).

<Preparation of structure for sliding material>:
The sliding material structure is made by mixing and heat-mixing raw materials of additives, crystalline thermoplastic resin, and compounding agents added as needed, and kneading and heat-melting them with a kneader. To form a desired shape. There is no restriction | limiting about the mixing apparatus of a shaping | molding raw material, It can be arbitrary mixing apparatuses. The kneading device
Any of a single-screw extruder, a twin-screw extruder, and a multi-screw extruder can be used.
There are no particular restrictions on the injection molding apparatus or the like.
The compounding agents added as necessary include, for example, antioxidants, light stabilizers,
UV absorbers, heat stabilizers, flame retardants, antistatic agents, antibacterial and antifungal agents, and the like.

<Thermoplastic resin sliding material>:

The thermoplastic resin-based sliding material of the present invention can constitute a sliding member of any form, and representative examples are gears, bearings, mechanism parts, etc. There is no. The sliding member itself may function independently, or may function as a part.

Examples of gears include various gears, face gears, worm gears, worm wheels, hypoid gears, racks, helical racks, involute bevel gears, involute spur gears, involute cylindrical gears, involutes. It can be a cylindrical spur gear, screw gear, octoid gear, speed increasing gear, speed reducing gear, partial gear, screw gear and the like.

The bearing has a function of sliding and rolling a component that moves relative to each other and a function of supporting a load, and can be various types of bearings.

The mechanical parts include, for example, carrier plates, bushes, wire guides,
It can be a wire drum, a seat belt anchor, a sun visor, a pie pig clip, a door wheel, a door lock actuator gear, a wiper motor gear, and other mechanical parts.
In the present invention, it is in accordance with the object of the present invention, and any modification or partial change and addition is optional as long as the effects of the present invention are not particularly impaired. It is.

EXAMPLES Next, although this invention is demonstrated concretely based on an Example, an Example is an illustration and does not restrain this invention.

A test piece was formed by obtaining heat melting, cooling and solidification under kneading from a forming raw material comprising a crystalline thermoplastic resin, an additive, and a compounding agent added as necessary. Table 1 below shows the compositions of the molding raw materials of Experiment Nos. 1-7. In Table 1, HDPE represents high-density polyethylene, VHDPE represents ultra-high molecular weight high-density polyethylene, PP represents polypropylene, PA6 represents nylon 6, and CF represents carbon fiber. In addition, CaCO ₃ is whisker-like calcium carbonate having an aspect ratio of 20 to 80 as a ratio of major axis to minor axis as an additive, aluminum borate is aluminum borate whisker, MgSO ₄ is magnesium sulfate whisker. Is shown. The compounding agents indicate compounding agents such as antioxidants, light stabilizers, ultraviolet absorbers, heat stabilizers, flame retardants, antistatic agents, antibacterial and antifungal agents. The numbers in Table 1 are
The weight% based on the weight of the molding raw material (total weight of thermoplastic tree, additive and compounding agent) is displayed.

The following Table 2 shows the results of measuring the coefficient of friction with a journal tester for test pieces molded from the molding raw materials of Experiment Nos. 1 to 7 in Table 1 obtained through the process of thermal melting and cooling / solidification under kneading. Show. Fig. 1 is an explanatory diagram showing the outline of the journal testing machine that measured the coefficient of friction. It is in contact with the inner surface of the test piece of the bush-shaped bearing material of Fig. 1 at a surface pressure of 0.5 MPa, and the mating shaft (aluminum shaft) is placed at room temperature.・ The friction coefficient was measured by rotating at a speed of 6 m / min without lubrication.
The numbers in the resin column corresponding to the experiment number in Table 2 are the same conditions for the thermoplastic resin in the molding raw material corresponding to the experiment number (the thermoplastic resin with the largest amount when there are multiple thermoplastic resins). It shows the coefficient of friction of the thermoplastic resin measured in. The reduction rate in Table 2 indicates the reduction rate of the friction coefficient when the friction coefficient of the thermoplastic resin and the test piece are compared. For example, the decrease rate of Experiment No. 1 is 60%, which means that the friction coefficient of the test piece of Experiment No. 1 is reduced by 60% from the friction coefficient of the thermoplastic resin that occupies the quantitative main body of the test piece. I mean.

Table 3 shows the results of measuring the amount of wear (mm) for the test pieces molded from the molding raw materials of Experiment Nos. 1 to 7 in Table 1 using a journal testing machine. The test conditions were the same as in the measurement of the friction coefficient, and the amount of wear after 50 hours was measured.
The number in the resin column corresponding to the experiment number in Table 3 is the thermoplastic resin in the molding raw material corresponding to the experiment number (if there are multiple thermoplastic resins,
It shows the amount of abrasion of the thermoplastic resin measured under the same conditions). The amount of change in Table 3 shows the amount of change when the amount of wear between the thermoplastic resin and the test piece is compared.

Experiments on the reinforcing effect of whisker-like calcium carbonate on high density polyethylene were conducted. FIG. 2 is a diagram showing the relationship between whisker-like calcium carbonate content and bending strength (MPa) of high-density polyethylene containing the whisker. The bending strength (MPa) was measured according to JISK7171. High density polyethylene containing whisker-like calcium carbonate
A whisker-like calcium carbonate-containing high-density polyethylene having a bending strength (MPa) 5% or more larger than that high-density polyethylene,
When the coefficient of friction was at least 10% smaller than that of the high-density polyethylene, it was found that the amount of wear did not change substantially even after 50 hours of sliding, as shown in Table 3. In other words, it was found that the difference was not the same as the progress of wear shown in FIG. 8 when the filler particles and the like exist.
Even if substances other than whisker-like calcium carbonate (for example, talc and other substances) satisfy the conditions (b) and (b) of the additive,
Similar results were obtained.

<Comparative Example 1>
Comparative test pieces in which various fillers were blended with high density polyethylene were molded under the same conditions as in Example 1. The filler is (b) of the additive of the present invention.
A substance that does not satisfy the condition (b) and has a substantially reinforcing effect on high-density polyethylene was selected.
The comparative test piece was prepared by blending 10 to 20% by weight of precipitated calcium carbonate powder alumina powder, silica powder, aluminum borate whisker, magnesium sulfate whisker and carbon fiber obtained by a chemical manufacturing method.
For each test piece for comparison, the amount of wear after 50 hours was measured in the same manner as in Example 3. Any test piece for comparison
The amount of wear increased significantly compared to high-density polyethylene, and the situation indicated by symbol B in FIG.
Aluminum borate whiskers and carbon fibers can be used in combination with whisker-like calcium carbonate, and are difficult to use alone.

According to the present invention, the sliding material is mainly composed of crystalline thermoplastic resin, and has higher lubricity (lower friction) and less wear than crystalline thermoplastic resin, and is highly lubricated and stable for a long time.・ A thermoplastic resin-based sliding material that enables safe and accurate sliding is provided.

It is explanatory drawing which shows the outline of a journal testing machine. It is a diagram which shows the bending strength of the high density polyethylene containing a whisker-like calcium carbonate. It is explanatory drawing of the sliding system in which a solid lubricant powder interposes on a sliding surface. It is explanatory drawing of the sliding system in which the lubricating oil which solid lubricant powder contains is interposed in a sliding surface. It is explanatory drawing of the sliding system in which a soft metal etc. interpose on a hard metal. It is explanatory drawing of the sliding system using the sliding surface which embedded the solid lubricant. It is explanatory drawing of the sliding system which provides the friction surface of a solid lubricant in a sliding member. It is a diagram which shows the abrasion progress curve of the resin bearing of a thermoplastic resin.

Claims (4)

The self-lubricating crystalline thermoplastic resin includes one or more additives that can be used as a reinforcing material and a crystal nucleus material thereof,
It has a sliding surface whose friction coefficient measured by a journal testing machine is 10% or less smaller than that of the crystalline thermoplastic resin, and its bending strength (MPa) measured by JISK7171 is 5% or more than that of the crystalline thermoplastic resin. A thermoplastic resin-based sliding material characterized by having a large structure. The self-lubricating crystalline thermoplastic resin includes one or more additives that can be used as a reinforcing material and a crystal nucleus material thereof,
(1) The additive has an aspect ratio indicated by a ratio of major axis to minor axis of 3 to
Formed into 100,
(2) It has a sliding surface whose friction coefficient measured by a journal testing machine is 10% or more smaller than that of the crystalline thermoplastic resin, and the bending strength (MPa) measured according to JISK7171 is higher than that of the crystalline thermoplastic resin. A thermoplastic resin-based sliding material characterized by having a large structure of 5% or more. The thermoplastic resin-based sliding material according to claim 1 or 2, comprising one or more of the following features (1) to (5).
(1) The thermoplastic resin is made of a crystalline olefin resin.
(2) The thermoplastic resin is a combination of a crystalline olefin resin and a polyamide resin.
(2) The thermoplastic resin is a combination of a crystalline olefin resin, a polyamide resin, and a polyacetal resin.
(4) The additive is made of an alkaline earth metal carbonate.
(5) The additive has an aspect ratio of 5 to 5 indicated by the ratio of the major axis to the minor axis.
Consists of 80 shapes. 3. The thermoplastic resin-based sliding material according to claim 1, comprising one or more of the following features (a) to (d).
(A) The thermoplastic resin is made of high-density polyethylene or polypropylene.
(B) The thermoplastic resin is composed of a combination of high-density polyethylene and nylon having a smaller amount ratio.
(C) The thermoplastic resin is composed of a combination of high-density polyethylene and nylon and polyacetal having a smaller amount ratio.
(D) The additive has an aspect ratio of 5 to 5 indicated by a ratio of major axis to minor axis.
It comprises an alkaline earth metal whisker-like carbonate represented by 80.