JPS63269161A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain good electric chargeability characteristics and high sensitivity and high durability by forming a specified lower interlayer and a specified upper interlayer in an electrophotographic sensitive body provided with a photoconductive layer made of a-Si. CONSTITUTION:The lower interlayer 2 and the upper interlayer 3 are made of an amorphous material containing at least Si and has a function using majority carriers same in polarity as carriers injected from a substrate 1. The upper interlayer 2 is made of a material obtained by applying a solution containing at least one of silyl isocyanate compounds represented by formulae I, II, and III, drying and hardening it. R in formulae I and I is 1-20C saturated alkyl, and R in formula III is H or methyl; and X is 1-20C saturated alkyl, thus permitting abnormal images to be prevented and sharp images to be obtained.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to electrophotographic photoreceptors, particularly dry type, wet type, RPC
The present invention relates to electrophotographic photoreceptors used in copying machines, NIPs, etc.

[Prior Art] Conventionally, electrophotographic photoreceptors have been prepared by providing a photosensitive layer mainly made of selenium or selenium alloy on a conductive support, or by disposing an inorganic photoconductive material such as zinc oxide or cadmium oxide in a binder. Generally known are those using dispersed materials, those using organic photoconductive materials such as poly-N-vinylcarbazole and trinitrofluorenone or azo pigments, and those using amorphous silicon.

Among them, an electrophotographic photoreceptor with a photoconductive layer made of amorphous silicon (hereinafter referred to as RA-SI J) has characteristics comparable to conventional Se-based photoreceptors and OPC, and is It has recently attracted particular attention because it has the advantages of being harmless to the environment and extremely durable.

However, the A-8i photoreceptor currently also has the following drawbacks, so conventional photoreceptors, especially those with high sensitivity,
It cannot be said that it has the overall ability to replace the AS2Se3 photoreceptor, which has great durability.

(1) The dark resistance of the conventional A-3I thermal photoreceptor is not necessarily sufficient to maintain an electrostatic latent image, and when an electrostatic latent image is formed in a copying machine, a considerable amount of electricity is charged on the surface of the photoreceptor. Even if a charge is applied, the dark decay is fast, and this charge may not be sufficiently retained until the development process.

(2) Environmental resistance characteristics: Abnormal images (image deletion, white spots, etc.) are likely to occur, especially at high temperatures and high humidity.゛Above (1), (2)
Several methods have been proposed to improve this problem. For example, on the surface of the a-8ii conductive layer, an a""1-x"
, a-8i1-xCx layer (Japanese Patent Application Laid-Open No. 57-115556)
, a-s r i-x Cx: H layer (JP-A-57-1
15551>, a-81-8Nx layer (JP-A-59-1
2448) or zirconium complex (JP-A-59-22
3440) and the like have been disclosed. However, even in such a photoreceptor, white spots, image deletion, etc. may occur at high temperatures and high humidity, and the photoreceptor is not perfect.

On the other hand, another drawback of the a-3i thermal photosensitive method is that (3) it is susceptible to variations in the composition structure of the surface of the conductive support (for example, AI) and adsorbed contaminants, which appear as abnormal images.

We are also aware of such issues.

The present inventors have previously proposed a photoreceptor with a novel layer structure (Japanese Patent Application Laid-open No. 6O-140357) as an effective countermeasure against this problem, and have shown that the concept can be applied to the A-3I thermal photosensitive method. However, even in this case, the above-mentioned drawbacks (1) and (2) are still included.

[Objective] The object of the present invention is to solve the above-mentioned drawbacks in an electrophotographic photoreceptor using a-3i in the photoconductive layer, to have good charging characteristics, high sensitivity, high durability, and to be suitable for all environments. An object of the present invention is to provide an electrophotographic photoreceptor.

An object of the present invention is to provide an electrophotographic photoreceptor that does not produce abnormal images at high temperatures and high humidity.

Another object of the present invention is to provide an electrophotographic photoreceptor that is resistant to the effects of contamination on the surface of a conductive support and that does not generate abnormal images due to the surface of the support.

[Structure] In order to reduce the influence of contamination on the surface of the conductive support, the present inventors have determined that, in order to reduce the influence of contamination on the surface of the conductive support, the carriers should not be recombined at the interface with the support, but at another newly created interface. I made sure that I could do it. It was also confirmed that this was effective in improving gradation and preventing white spots and white streaks.

Therefore, the present invention provides an electrophotographic photoreceptor having the structure as described in the claims.

To further explain the above structure, as the upper intermediate layer (intermediate layer between the photoconductive layer and the surface protective layer),
By providing a layer containing a substance, not only the adhesion between the a-3i-based photoconductive material and the surface protective layer is greatly improved, but also because the intermediate layer has a charge retention ability, it is possible to
It was confirmed that the problems of low charging ability and poor dark decay characteristics, which were considered to be problems with the 3i-based photoreceptor, could be solved at the same time.

The intermediate layer and surface protective layer play the roles of oxygen, moisture, ozone, and alkali ions (Na) present in the usage environment.
It was confirmed that the photoconductive layer also has the function of preventing molecular species that are likely to affect the a-3i photosensitivity, such as ", K"), from coming into direct contact with and adsorbing to the photoconductive layer.

The invention will be explained in more detail below with reference to the accompanying drawings. FIG. 1 shows a photoreceptor in which a lower intermediate layer 2, an a-3i photosensitive (photoconductive layer) 3, an upper intermediate layer 4, and a protective layer 5 are provided on a support (conductive support) 1. There is.

As described above, the lower intermediate layer 2 of the photoreceptor of the present invention has a function in which carriers having the same polarity as the carriers injected from the support 1 during charging become majority carriers. Therefore, in the case of a photoreceptor for positive charging process, the lower intermediate layer 2 is n
The photosensitive layer 3 must be i-type or p-type. Further, in the case of a photoconductor for a negatively charged process, the lower intermediate layer 2 must be of p-type, and the photosensitive layer 3 must be of 1-type or n-type.

That is, the photosensitive layer 3 has opposite polarity or intrinsic properties to the lower intermediate layer 2.

Now, to explain the photoreceptor of the present invention when, for example, a positive charging process is measured, the carriers injected from the support 1 during charging are electrons. At this time, the n layer in which electrons serve as majority carriers is used as the lower intermediate layer 2, and the p layer in which holes of opposite polarity serve as majority carriers is used as the photosensitive layer 3. Therefore,
During light irradiation following charging, the holes traveling through the photosensitive layer 3 toward the support 1 and the electrons injected from the support 1 are p.
-n-layer interface (i.e., the interface between the photosensitive layer 3 and the lower intermediate layer 2)
will be recombined.

As the conductive support 1, for example, AI, stainless steel, or any other material commonly used in this field can be used. Further, resin films or sheets, paper, glass, etc. whose surfaces have been electrically conductively treated can also be effectively used as the support 1. Note that examples of the above-mentioned "conductive treatment" include lamination and vapor deposition with metal. The shape of the support 1 may be cylindrical, belt-like, plate-like, etc. depending on the purpose.

When the lower intermediate layer 2 is composed of an amorphous 3i-based material layer, a-3i may contain oxygen and/or nitrogen and/or carbon, and is an element of group Ⅰ A of the periodic table. (B,
A I, Ga, in, TI, etc.) or Group V A of the periodic table
Elements (PlAs, Sb, etc.) may be added as necessary. This material can be formed by glow discharge method, sputtering method, ion blating method, electron beam method,
This can be done by known means such as ion implantation, but glow discharge and sputtering are more advantageous if various points are taken into consideration.

When employing the glow discharge method, the raw material gas is mixed with a diluent gas in an appropriate ratio as needed, and this is introduced into the vacuum deposition chamber where the support 1 is installed to turn it into gas plasma. good.

Raw material waste and Ll; ts i , N, O, CSH and/or F, and further atoms constituting at least one of the elements of Group I A of the Periodic Table (or elements of Group V A of the Periodic Table) A gaseous substance or a gasified substance that can be gasified is used. Even if the raw material gas is a mixture of raw material gases having constituent atoms of each component at a desired mixing ratio, 2
A raw material gas having the above-mentioned components as constituent atoms may be mixed with a raw material gas having one component as constituent atoms.

Further, as a starting material that can become the raw material gas, for example, SiH4,5i2t- whose constituent atoms are Si and H
Examples include 82 H6, which has H and B as constituent atoms, such as 16.

H2, N2, NH3,02, C02, CH4, C2H6
, C2H4, CF4, PH3, AS83, etc. are also useful.

When a sputtering method is employed, a single crystal or polycrystalline 3i wafer or a wafer containing Si may be used as a target and sputtered in an appropriate gas atmosphere. As the gas here, the raw material gases listed in the glow discharge method can be effectively used.

The diluent gas used in these methods is He.

Examples include Ne, Ars H2, etc.

Since the lower intermediate layer 2 in the present invention must have the above-mentioned specific functions, the formation of the layer 2 must be performed in such a way as to impart such functions. Depending on whether the lower intermediate layer 2 composed of an amorphous material layer is p-type or n-type, impurities doped into a-3i (N, H and/or F1 elements of group Ⅰ A of the periodic table) are doped into a-3i. , elements of group V A of the periodic table) are different, and can be determined by experiment.

That is, according to what the inventors have learned through experiments, in order to form p-type, C@:O ~ 20 atomic%, N at i,
o ~ 20.0 atomic%, H 5.0 ~ 3560 atomic%, elements of Group Ⅰ A of the periodic table 50 ~ 11000
PP doping is sufficient. In addition, if necessary, halogen is 5.0 to 35.0 atomic% and 0 is 0.02 to 35.0 atomic%.
It may be doped in the range of 5.0 atomic percent. In reality, since B is often used as an element in group Ⅰ A of the periodic table, the above-mentioned elements in group Ⅰ A of the periodic table are 50 to 1 oo
oppm is the gas mixture ratio as B2H&. On the other hand, in order to form n-type, in a-3i, C should be 0 to 20 atomic %, N should be 1.0 to 20,0 atomic %, H should be 5.0 to 35.0 atomic %, and the periodic law should be What is necessary is just to dope 50-11000 pp of the element of group V A of a table|surface. Further, if necessary, halogen may be doped in a range of 5.0 to 35.0 atomic %, and O may be doped in a range of 0.02 to 5.0 atomic %.

In reality, p is often employed in the elements of group V A of the periodic table, so the elements of group V A of the periodic table 50 to 1 o
ooppm is the gas mixture ratio as PH3. In this case, the thickness of the lower intermediate layer (a-3i intermediate layer) is 100X
~5 μm, preferably 500 ~1 μm is appropriate. 1
If it is thinner than 00A, the carriers generated in the photosensitive layer will pass through the lower intermediate layer to the support due to the so-called tunnel effect, so the recombination surface will be the support surface.On the other hand, if it is thicker than 5μm, the carriers injected from the support will be effective. This makes it difficult to reach the interface between the lower intermediate layer and the photosensitive layer.

As described above, the photosensitive layer 3 is composed of an n-type or an i-type when the lower intermediate layer 2 is a p-type, and a p-type or an i-type when the lower intermediate layer 2 is an n-type.

In the a-8t system, in addition to a-5i, 01N, O, H and/or F1 elements of group Ⅰ A of the periodic table or elements of group V A of the periodic table (P, AS, Sb.

3i, etc.), and are classified into p-type, i-type, and n-type depending on the combination of impurities and the amount added. This is the same as in the case of the amorphous material intermediate layer.

For example, in order to make a p-type in such a-3i-based adverse photosensitivity, it is sufficient to add an appropriate amount of an element of group Ⅰ A of the periodic table. However, taking B as an example, the gas mixture ratio is B2 H6
It is sufficient to add about 100 to 11,000 pp. To make n-type, a-3i:H, a-8i:N:l-1, a
In the case of -8i:C:N:H, it is somewhat n-type even if no impurities are added, but preferably, an appropriate amount of elements from VIA of the periodic table may be added. For example, in the case of P, , PH3 is about 10 to 1000 ppm as a gas mixing ratio. Also, to form i-type, use a-3i:N:H.

a-8i:Q:N:) (in the case of B as the gas mixture ratio
2 H6 may be added in an amount of about 10 to 1100 pp. In addition, in the case of a-3i:Q:1-1, it is almost i-type by itself (without adding other impurities).

The thickness of the photoreceptor is 5 to 100 μm, preferably 10 to 4 μm.
It is 0 μm. If it is thinner than 5 μm, a sufficient surface potential cannot be obtained, and the irradiated light reaches the lower intermediate layer, generating extra photocarriers, and as a result, it becomes susceptible to the adverse effects of the support interface. On the other hand, if it is thicker than 100 μm, it is not preferable because it becomes easy to peel off and increases the cost of the photoreceptor.

The formation of the a-3i-based adverse photosensitive photosensitive material 3 is achieved by forming the amorphous material lower intermediate layer 2.
Similar measures can be taken as in the case of .

In the photoreceptor according to the present invention, as described above, it is a condition that the photosensitive layer 3 and the lower intermediate layer 2 have a specific relationship, and therefore, the photosensitive layer,
It is necessary to select the constituent material of the lower intermediate layer.

The general formula (I>
Specific examples of silyl isocyanate compounds represented by No. 1 trimethylsilyl isocyanate (CH3
>38iNCO No, 2 Dimethylsilyl diisocyanate (CH3
) 2 Si (NCO) 2No, 3 Methylsilyltriisocyanate CH35i (NCo)3 No, 4 Octadecylsilyltriisocyanate CleHxtS i (NGO>3 No, 5 Dodecylsilyltriisocyanate 012
H25S i (NGO > 3 No, 6 Stearylsilyltriisocyanate C12l-1353i (NCO > 3 No, 7 Trioctadecylsilyl isocyanate (C1lIH3T) 33 i (NCO) No, 8
Didodecylsilyl diisocyanate (CI2 Hl5
) 2 S i (NGO) 2NO,9 diethylsilyl diisocyanate (C2H6) 2 S i (N
CO> 2N0.10 Butylsilyl triisocyanate C4H9S i (NGO> 3 N0.11 Dipropylsilyl diisocyanate (C
3H7) 2 S i (NCO>2N o, 12
Ethylsilyltriisocyanate C2H5Si (NC
O)3 NO,13 triethylsilyl isocyanate (C21-
1s>33iNc.

No. 14 Tripropylsilyl isocyanate (C
3H7) 3SiNCO N O,15propylsilyltriisocyanate C:+
HrSi (NGO>3 No, 16 Tetraisocyanate silane Si
(NGO > 4, etc.)

Similarly, specific examples of the silyl isocyanate compound represented by the general formula (■) include No, 17 CH30Si (NGO>3No, 18
(CHxO)28i(NCO>2N0.19 (
CH30) 3siNc.

NO,20C2H50S i (NCO)2N0.2
1 C2H508i (NGO>3NO, 22(C
2H50> 23 i (NGO) 2No, 23
(C2HsO)3siNc.

No, 24 (Ca HIT O> 38 i N
C0N0.25 (CsH+70>28i(NGO>
2No, 26 Ca HITO8i (NCO)3
NO, 27C4H90S i (NCO>3No, 2
8 C6Hl)O3i (NCO>3No, 29
Co HI70S i (NCO>3N0.30
(CIOH2IO>38 i NC0N0.3I
Cl2H million O3i (NCO>3N0.32 0IS
H3103i (NGO> 3N0.33 (C
I88370) 23 i (NGO>2N0.34
(02118QIO) 3Si (NCO) etc.

Further, specific examples of the silyl isocyanate compound represented by the general formula (III) include NO, 37CH3-C
H-8i (NGOLNO, 39CH2=CH-3i (
CH3) 2-NGONO,52(CH2-CH) 3
5i-NCONO, 53 (CH2= CCH2) 3s
i-NCONo, 54 (CH2-CH)2si(N
GO)2, etc.

The thickness of the intermediate layer can be set arbitrarily, but it is 10 μm or less and 0.01 μm or more, preferably 1 μm or less.
．． 05 μm or more, particularly 0.5 μm or less, and iμm or more are preferable. The intermediate layer can be formed by a method such as a dipping method, a spray method, or a vapor phase method.

The silyl isocyanate compound is 5i-Nco as described above.
It has a bond and forms a silicon oxide film through a moisture decomposition reaction as described below.

-3i-NCO+2H20→-3i-OH+NH3+C
O2-3i-OH+-3i-OH→[5i-0-3i]
.

Therefore, a silicon oxide film forming agent can be produced using a compound having a 5i-NCO bond as a basic component. Alkyl silicates, organic polymers, and inorganic polymers can also be used in combination if necessary. Further, metallosiloxane bonds can be formed by adding titanium, zirconium, tin, aluminum, antimony, etc.

The present invention was made based on the discovery that an intermediate layer with excellent properties can be formed by utilizing the properties of such silyl isocyanate compounds.

These compounds can be used alone or as a mixture of two or more. Further, in order to improve adhesion, a mixture of the above-mentioned silyl isocyanate compound and another organic compound and, if necessary, a catalyst may be added.

The material for the protective layer 5 is not particularly limited to organic/inorganic polymer compounds, ceramics, etc. that are generally used as protective layer materials, but the material must be one that does not cause an increase in residual potential during repeated use in a copying machine, and has high resolution. It is preferable to use something that does not adversely affect basic images such as sharpness.

The inventors' study results show that the basic physical properties of the protective layer include a light transmittance of 70% or more in the effective wavelength range, preferably 80% or more.
0% or more, and the electrical resistivity is 109 to 1013 Ω-c
It was confirmed that a good surface protective layer can be obtained if m1 preferably satisfies 10 to 10 I2 Ω·cm.

Examples of mounting bodies that satisfy such conditions include general organic polymer compounds such as polystyrene and MMASn-BM.
A, polyamide, Ho'J ester, polyurethane, polycarbonate, polyvinyl formal, polysilicone, polyvinyl acetal, polyvinyl butyral, ethyl cellulose, melamine resin, and copolymers thereof,
A mixture or the like to which an appropriate amount of a conductivity control agent such as an organic compound or an inorganic compound is added is used. Specifically, organic compounds include metallocene compounds, and inorganic compounds include gold, silver, copper, nickel, and alumium powders, zinc oxide, titanium oxide, tin oxide, indium oxide, and antimony oxide, tin oxide, and indium oxide. Examples include tin oxide.

The thickness of the protective layer 5 is suitably 0.5 to 10 .mu.m, preferably 1 to 5 .mu.m.

As described above, the photoreceptor of the present invention has a layer in which the majority carrier is a carrier of the same polarity as the carrier injected from the support during charging, as the lower intermediate layer (a layer provided between the support and the photosensitive layer). It is something. However, it is an electrophotographic photoreceptor in which a lower intermediate layer and a photoconductive layer are sequentially laminated on a conductive support, and the intermediate layer prevents the flow of carriers from the support side into the photoconductive layer, and is also capable of preventing carriers from flowing into the photoconductive layer by light irradiation. Although it is possible to provide a function of allowing carriers generated in the photoconductive layer and moving toward the support to pass from the photoconductive layer side to the support side, such a photoreceptor inevitably tends to have an increased residual potential. In addition, it is sensitive to the influence of contaminants on the surface of the support, which tends to appear as abnormal images, making it impossible to achieve the object of the present invention.

Further, in the present invention, the above-mentioned surface protective layer is laminated, which can satisfy charging characteristics, dark decay characteristics, and environmental resistance characteristics at the same time.

The photoreceptor of the present invention may be one for an ordinary copying machine or a printing drum of a printing machine to which electrophotography is applied.

It can also be applied as a photoreceptor for NIP such as LD printers, LED printers, and liquid crystal printers.

Hereinafter, the present invention will be specifically explained with reference to Examples. Note that the amounts (parts) of each component described in the Examples are parts by weight.

Example ■ Using a coaxial co-tube type glow discharge device, 80φx 340
An electrophotographic photoreceptor was prepared by providing a lower intermediate layer and a photoconductive layer on a mm aluminum drum (support). In addition, the substrate temperature is 230℃, the discharge frequency is 13.56M H2, and the discharge power is 0.
．． The test was conducted under the conditions of 24 W/cm2, reaction pressure o, and 8 Torr, and the thickness of the lower intermediate layer was 4000 A, and the thickness of the photosensitive layer (photoconductive layer) was 18 μm. The specific composition is shown in Table ■.

An upper intermediate layer and a surface protective layer were laminated on the obtained photosensitive layer according to the composition and manufacturing procedure shown below.

Upper intermediate layer: Composition Tetraisocyanate silane 4 parts Methylsilyl triisocyanate 4 parts n-butyl acetate 72 parts Preparation procedure After dip coating on the photosensitive layer, it was dried for 2 hours at room temperature and humidity of 55-65% RH to a film thickness of 0. A 14 μm upper intermediate layer was obtained.

Surface protective layer: Composition: Ester crosslinked styrene-MMA resin liquid (solids concentration 4
0% solvent n-butanol + toluene) 40 parts SnO2 fine particles 24 parts Toluene/n-butanol (9/1) mixed solvent 55 parts Preparation procedure After dispersing in a ball mill for 120 hours, dip-coat on the above intermediate layer and dry at 120 ° C. for 30 minutes. After curing, a surface protective layer of about 5 μm was obtained.

The photoreceptor produced in this way is shown as a comparative example (Table ■), as well as its charging characteristics, dark decay characteristics, image characteristics, and humidity resistance (
When the image characteristics (image characteristics at 30° C. and 90% lower temperature) were examined, Example (2) according to the present invention showed extremely good characteristics as shown in Table (2) below.

Surface Nail Example ■ The support, lower intermediate layer, photosensitive layer, and surface protective layer were prepared under the same conditions as in Example I-1 and Example I-2, respectively, and only the upper intermediate layer was manufactured using the following composition and manufacturing procedure. A photoreceptor was prepared by forming the photoreceptor.

Upper middle layer: Composition Ethoxysilane triisocyanate C21-1s O3i (NGO> 3 10 parts n-butyl acetate 70 parts Preparation procedure Dip coating → Dry at room temperature and humidity 50-60% for 2 hours,
An upper intermediate layer having a thickness of 0212 μm was obtained.

The test results of this photoreceptor are shown in Table 2 below.

Table ■ Example ■ The support, lower intermediate layer, photosensitive layer, and surface protective layer were produced under the same conditions as in Example I-1 and Example I-2, respectively, and only the upper intermediate layer was produced using the following composition and production procedure. A photoreceptor was manufactured by forming a photoreceptor.

Upper middle layer composition 10 parts vinylsilyl triisocyanate n-butyl acetate
70 copies Preparation procedure After coating by dip coating on the photosensitive layer, it was dried and cured for 2 hours at 25° C. and 65% RH, and an upper intermediate layer having a thickness of 0.20 μm was laminated thereon.

The test results of this photoreceptor are shown in Table 2 below.

Table ■ [Effects] (1) By laminating the upper intermediate layer and the surface protective layer according to the present invention, the charging potential is improved, the dark decay characteristics are improved, and abnormalities such as white spots and image blurring at high temperatures and high humidity are prevented. Image generation is prevented.

(2) In the electrophotographic photoreceptor according to the present invention, carrier recombination occurs at the interface between the lower intermediate layer and the photosensitive layer (photoconductive layer), so the residual potential is extremely low or almost nonexistent;
It is extremely unlikely that contamination of the support surface will have an adverse effect on the image.

This means that clear images can be obtained, and there is also greater freedom in terms of surface cleanliness (cleaning method, campus cleanliness, etc.) and handling during photoconductor production, which greatly reduces costs and work. effect is brought about.

(3) Due to the presence of the lower intermediate layer, the film growth of the photosensitive layer during the production of the photoreceptor becomes uniform both in the surface direction and in the film direction, so the number of abnormal points (for example, crystallized areas) is drastically reduced, resulting in abnormal images. Occurrence is prevented.

[Brief explanation of drawings]

The drawing is a schematic cross-sectional view showing the structure of the electrophotographic photoreceptor of the present invention. DESCRIPTION OF SYMBOLS 1... Conductive support body, 2... Lower intermediate layer, 3...
Photoconductive layer, 4... Upper intermediate layer, 5... Surface protective layer.

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor comprising, in order, a lower intermediate layer, a photoconductive layer, an upper intermediate layer, and a surface protective layer on a conductive support, wherein the lower intermediate layer and the photoconductive layer are made of at least silicon. This lower intermediate layer is made of an amorphous material containing atoms, and has a function in which carriers having the same polarity as the carriers injected from the support during charging become majority carriers, and the upper intermediate layer has the following general formula (I). An electrophotographic photoreceptor comprising a material obtained by coating, drying, and curing a solution containing at least one silyl isocyanate compound represented by any one of , (II), and (III). General formula I (R)-_mSi-(NCO)_4_-_m, where R: saturated alkyl group having 1 to 20 carbon atoms, m: any of 0, 1, 2 or 3, General formula II (RO)-_mSi -(NCO)_4_-_m However, R: Saturated alkyl group having 1 to 20 carbon atoms m: Any of 1, 2 or 3, General formula III ▲There are numerical formulas, chemical formulas, tables, etc.▼ However, R: Hydrogen or Methyl group, X: saturated alkyl group having 1 to 20 carbon atoms, m: 1, 2 or 3, l: 0, 1 or 2.