JP3111814B2 - Heat-shrinkable silicone rubber composition having antibacterial and antifungal properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-shrinkable silicone rubber used for coating various articles with silicone rubber. More specifically, the present invention relates to a heat-shrinkable silicone rubber which has antibacterial properties without impairing the inherent properties of silicone rubber such as heat resistance. The present invention relates to a heat-shrinkable silicone rubber composition that imparts mold resistance.

[0002]

2. Description of the Related Art
Various types of silicone rubber molded products that shrink by heating, such as tubes, sheets, molds, etc., have been developed. It is used for various purposes.

A heat-shrinkable silicone rubber composition used in the field of silicone coating is generally a composition obtained by blending a thermoplastic resin such as polyethylene, polystyrene, or acrylic resin or a silicone resin with a silicone rubber material ( JP-B-51-7704, JP-B-56-
No. 9182).

However, conventionally, these silicone rubber compositions have excellent properties inherent to silicone rubber such as heat resistance, cold resistance, weather resistance, rubber elasticity, etc. of silicone rubber, but have antibacterial properties and mold resistance. It was difficult to do. That is, according to the study of the present inventor, in the case of heat-shrinkable silicone rubber, there are steps of heat vulcanization and hot stretching, and therefore, organic benzimidazole, binazine, methylsulfonyl, etc., which generally provide antibacterial properties. In addition, when a compound is blended, there is a problem that the molded product is deteriorated and discolored, and these chemicals are deteriorated under the influence of a change in temperature, ultraviolet rays, humidity and the like, and there is a problem in persistence of the effect.

[0005] However, in recent years, medical treatment which requires prevention of bacterial infection and mold generation through the surface of the coating,
In the food field, the electric field, and the electronic field as well, antibacterial properties and fungicidal properties are required in view of the problem of bacterial propagation at high temperatures. It is important that the orthodontic wire coating in orthodontics has antibacterial properties.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a heat-shrinkable silicone rubber composition that provides a long-lasting antibacterial property and antifungal property without impairing the inherent properties of silicone rubber. And

[0007]

Means and Action for Solving the Problems The present inventors have
As a result of intensive studies to achieve the above object, by blending the heat-shrinkable silicone rubber composition with an antibacterial ceramic, the antibacterial property with a long lasting property without impairing the original properties of the heat-shrinkable silicone rubber. It was found that moldability can be imparted.

That is, antibacterial ceramics have excellent heat resistance, are very high in safety, and have a long-lasting effect, unlike organic antibacterial agents. Therefore, they are blended with a heat-shrinkable silicone rubber composition. It is stable even after processes such as heat vulcanization and hot stretching, and at the compounding amount enough to impart antibacterial properties, the original physical properties of silicone rubber are not impaired, and antibacterial properties and mold resistance are maintained, The present inventors have found that this is an optimum antibacterial agent for heat-shrinkable silicone rubber, and have accomplished the present invention.

Accordingly, the present invention provides (A) the following average composition formula (1): R ¹ _n SiO _{(4-n) / 2} (1) (wherein R1 is the same or different unsubstituted or substituted 1
Represents a valent hydrocarbon group, and n is an average number of 1.9 to 2.1. ): 100 parts by weight; (B) an organopolysiloxane resin or thermoplastic resin having a softening temperature in the range of 50 to 200 ° C .: 5 to 100 parts by weight; (C) a crosslinking agent and / or a curing catalyst. : An effective amount for curing the component (A); and (D) a silver phosphate ceramic: 0.1 to 20 parts by weight as an essential component, a heat-shrinkable silicone rubber having antibacterial and antifungal properties. A composition is provided.

Hereinafter, the present invention will be described in more detail. The heat-shrinkable silicone rubber composition having antibacterial and antifungal properties of the present invention has a heat-shrinkable composition containing the components (A) to (C) as described above. It is obtained by blending the antibacterial ceramic of the component (D) with the water-soluble silicone rubber composition.

The organopolysiloxane (A) constituting the heat-shrinkable silicone rubber composition of the present invention is represented by the following average composition formula (1). R ¹ _n SiO _{(4-n) / 2} ... (1)

In the above formula, R ¹ represents the same or different unsubstituted or substituted monovalent hydrocarbon group having preferably 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, such as methyl group, ethyl group, Alkyl groups such as propyl group and butyl group; cycloalkyl groups such as cyclohexyl group; alkenyl groups such as vinyl group, allyl group, butenyl group and hexenyl group; aryl groups such as phenyl group and tolyl group; Examples thereof include a 3,3,3-trifluoropropyl group and a 2-cyanoethyl group in which part or all of the hydrogen atoms bonded to the atoms are substituted with a halogen atom, a cyano group, or the like. It is preferable that 0.001 to 15 mol%, more preferably 0.01 to 5 mol% of R ¹ is an alkenyl group, particularly a vinyl group. N is a positive number between 1.9 and 2.1.

The organopolysiloxane represented by the above formula (1) is preferably one whose molecular chain end is blocked with a trimethylsilyl group, dimethylvinyl group, dimethylhydroxysilyl group, trivinylsilyl group or the like.
Further, it is basically preferably linear, but may be one kind or a mixture of two or more kinds having different molecular structures.

In the case where the component (C) described below undergoes addition reaction crosslinking by combining an organohydrogenpolysiloxane and a platinum-based catalyst, the organopolysiloxane of the above formula (1) has at least two alkenyl groups. There is a need.

The organopolysiloxane represented by the above formula (1) preferably has an average degree of polymerization of from 100 to 30,000, particularly preferably from 3,000 to 10,000, and has a viscosity at 25 ° C. of at least 100 cs (centistokes), especially at least 100,000. Those which are 10000000cs are preferable.

On the other hand, the softening temperature of the component (B) is 50 to 20.
The organopolysiloxane resin or the thermoplastic resin in the range of 0 ° C. is a component that imparts heat shrinkability. When the softening temperature is lower than 50 ° C., after stretching (expansion), the shape,
Those that cause dimensional changes, while those above 200 ° C., require high temperatures to shrink and are not practical. A preferred softening temperature range is 60 to 180 ° C.

Such an organopolysiloxane has an essential structure of R ¹ SiO _1.5 unit,
¹ ₂ SiO units, those containing R ¹ ₃ SiO _0.5 units (wherein,
R ¹ has the same meaning as described above), and specifically, C ₆ H ₅
SiO _1.5 units, CH ₃ SiO _1.5 units, (CH _{3) 2} Si
O units, (CH ₃ ) (CH ＝ CH) SiO units and the like are preferred, and can be obtained by co-hydrolyzing and condensing various silanol monomers and chlorosilane at a desired mixing ratio.

Examples of the thermoplastic resin include polyethylene, acrylic resin, polypropylene, polyamide, and polyvinylidene fluoride, but are not particularly limited as long as the softening temperature is within the above range.

The amount of the component (B) is as follows:
It is necessary to be in the range of 5 to 100 parts, preferably 10 to 80 parts with respect to 00 parts. If the amount is less than this range, heat shrinkage cannot be imparted. If the amount is too large, the physical properties of the molded article as a rubber elastic body deteriorate.

The cross-linking agent and / or curing catalyst of the following component (C) comprises a composition together with the above-mentioned components (A) and (B), and is formed by a molding heating method and a method of irradiating ionizing radiation after molding. It is a component for cross-linking to form a rubber elastic body. Therefore, it is appropriately selected according to the crosslinking method of the silicone rubber composition, and those conventionally used generally may be appropriately selected and used. For example, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, diter Organic peroxides such as tert-butyl peroxide and tertiary butyl perbenzoate; organohydrogenpolysiloxanes having at least three hydrogen atoms bonded to silicon atoms in one molecule; and platinum-based catalysts such as platinum element and chloroplatinic acid A combination of the above is exemplified.

The amounts of these crosslinking agents and curing catalysts are appropriately selected, but are preferably 0.1 to 5 parts with respect to 100 parts of the organopolysiloxane (A). , The organohydrogenpolysiloxane has a molar ratio of alkenyl groups bonded to silicon atoms of the organopolysiloxane (A) to SiH (SiH
/ Si-alkenyl group) is 0.5 to 5 and the platinum-based catalyst is preferably 0.1 to 2000 ppm based on the component (A).

Thus, in the present invention, the above (A) to (A)
A silver phosphate ceramic is blended with the heat-shrinkable silicone rubber composition containing the component (C) as the antibacterial ceramic (D). Examples of the antibacterial ceramic include silver phosphate ceramics represented by the following composition formula (2). _{Ag-Ca u Zn v Al w} (PO 4) x (OH) y ... (2) ( where, wherein u, v, w, x, y are positive numbers.)

[0023]

The silver phosphate ceramics are obtained by combining silver ions with a phosphate double salt ceramic in which calcium and zinc are combined, and commercially available products include antibacterial ceramics manufactured by Shinto Kogyo Co., Ltd. it can.

[0025]

The loading of these silver ions in the ceramic is about 0.1 to 15% by weight, preferably about 0.5 to 5% by weight.

The amount of the antibacterial ceramic is 0.1 to 20 parts, preferably 0.5 to 10 parts, per 100 parts (parts by weight, hereinafter the same) of the organopolysiloxane (A) described later. Range. If the amount is less than 0.1 part, the antibacterial effect cannot be sufficiently exhibited, while if it exceeds 20 parts, the processability becomes poor and the mechanical properties of the molded product are insufficient.

The composition of the present invention preferably further contains (E) a silica-based inorganic filler from the viewpoint of reinforcing properties. Examples of the silica-based inorganic filler include finely powdered silicic acid anhydride produced by a dry method, or natural silicic acid or silicate, hydrous silicic acid produced by a wet method, quartz powder, and various kinds of silane, low polymerization Degree organopolysiloxane,
Those treated with silazane or the like are exemplified. These have a relatively large particle size, resulting in a product having poor mechanical strength.
0 m ² / g or more, more preferably 100 to 400 m ² / g
It is preferably a fine powder which is

The amount of the component (E) is 100
It is necessary to be in the range of 5 to 100 parts, preferably 10 to 50 parts per part. Outside this range, various properties such as mechanical strength and rubber elasticity of the obtained silicone rubber are deteriorated, which is not practical.

The heat-shrinkable silicone rubber composition of the present invention can be obtained by mixing these components, and the mixing method is generally used such as a roll, a kneader, a Banbury mixer (internal mixer) and the like. If necessary, a dispersing agent for facilitating uniform mixing, or a heat resistance improver, a flame retardant, a colorant, etc. may be used. .

In mixing, the method of uniformly dispersing the component (B) depends on the form of the organopolysiloxane resin or the thermoplastic resin. For example, when the particle diameter of the component (B) is small, kneading at a temperature lower than the softening temperature is performed. When the particle size is large, kneading at a temperature higher than the softening temperature is preferred from the viewpoint of mechanical strength.

The silicone rubber composition thus obtained can be formed into a desired shape such as a pipe, a sheet, or a shaped article according to a general rubber molding method such as compression molding, extrusion molding, calendar molding, transfer molding, injection molding and the like. And then cross-linked and cured to obtain a silicone rubber molded article, which is then heated to a temperature equal to or higher than the softening point of the component (B) in the composition and stretched. By cooling, an excellent heat-shrinkable silicone rubber molded product (product) can be obtained.

The heat-shrinkable silicone rubber composition of the present invention has a heat resistance and a weather resistance inherent in the heat-shrinkable silicone rubber.
It has properties such as cold resistance and rubber elasticity, as well as antibacterial properties and fungicidal properties, and has high stability. Therefore, it prevents bacterial infection through the coating, and the appearance of the coating is kept clean for a long time due to its antibacterial and fungicidal properties, thus preventing contamination under adverse environments such as high temperature and under various germs. For extending the life of the product. For this reason, in addition to the use of heat-shrinkable tubes and molded products (doorknob coating, handrail coating, etc.), medical and food-related parts prevent hospital infection, improve the living environment, improve food hygiene, and improve product life. It has effects such as extension, and it also has antibacterial and antibacterial properties over a long period of time, such as wire coating in the field of orthodontics used in the oral cavity, and prevention of contamination by joint coating of connectors for electric and electronic parts and home appliances. Due to its moldability, it can be used in a wide range of applications.

[0034]

The heat-shrinkable silicone rubber composition having antibacterial and antifungal properties of the present invention has antibacterial properties and antifungal properties while having the properties inherent in heat-shrinkable silicone rubber.

[0035]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the following examples, all parts are parts by weight.

Examples 1 and 2, Comparative Example 1 (CH_Three)_TwoS
99.8 mol% of iO units and (CH_Three) (CH_Two= CH)
It is composed of 0.2 mol% of SiO unit,
A polymer having an average degree of polymerization of about 8000
100 parts organopolysiloxane, silica filler
(Product name Aerosil R-972, manufactured by Nippon Aerosil Co., Ltd.)
30 parts, organopolysiloxane resin (composition: C₆H_Five
SiO_1.530 mol% unit, CH_ThreeSiO_1.5Unit 65m
%, (CH_Three)_Two4 mol% of SiO units, (CH_Three) (C
H_Two= CH) SiO unit 1 mol%, softening temperature 100-1
20 ℃) Heat and mix 20 parts with a kneader, and after cooling, antibacterial
Ceramics (trade name VB-100N, containing 1% Ag)
Product, manufactured by Shinto Kogyo Co., Ltd.)
Mix uniformly, and as a crosslinking agent
Hydrogenpolysiloxane (where Me is a methyl group
) And chloroplatinic acid in isopropanol (platinum
0.1% (concentration: 1%)
m-thick sheet-like material, and heat it at 150 ° C.
Heating was performed in an air dryer for 30 minutes to obtain a vulcanized sheet. Get
The sheet obtained was milky white and had no discoloration. Comparative example and
Process without adding only antibacterial ceramics
Thus, a vulcanized sheet was obtained.

[0037]

Embedded image

With respect to the obtained vulcanized sheet, hardness, elongation and tensile strength were measured based on JIS K6301, and the stretch retention and heat shrinkage were measured according to the following methods. The results are also shown in Table 1. <Measurement methods for stretch retention and heat shrinkage>
S No. 2 The sample was punched out with a dumbbell and a test piece was collected. A straight line (marked line) having a length of 2 cm was attached to the center of each test piece, heated in an oven at 200 ° C. for 30 minutes, and then stretched so that the marked line became approximately 5 cm. It was fixed and cooled as it was in the air at room temperature. The length of the mark when fixed to the jig is L ₁ , the length of the mark when removed from the jig after cooling and allowed to stand at room temperature for 24 hours is L ₂ , and 200 ° C. after removal from the jig The length of the marked line when heated and cooled for 5 minutes is L ₃ , and the original length of the marked line is L ₀ (= 2 cm).
The stretch retention and the heat shrinkage were determined by the following formulas.

[0039]

(Equation 1)

[0040]

[Table 1]

<Antimicrobial Test> The vulcanized sheets obtained in Examples 1 and 2 and Comparative Example 1 were subjected to an antimicrobial test according to the following method.

Each of the bacteria shown in Table 2 was used as a specimen (about 30 mm).
× 20 mm), and a polyethylene film was adhered thereto and stored at about 35 ° C., and the number of viable bacteria at 1, 3, and 6 hours after the start of storage was measured. The results are also shown in Table 2. The test method is shown below. Test method (1) Test strain Escherichia coli IFO 3301 (Escherichia coli) Staphylococcus aureus IFO 12732 (Staphylococcus aureus) Psaudomonas aeruginosa IID P-1 (Pseudomonas aeruginosa) 3) Preparation of bacterial solution Escherichia coli and Pseudomonas aeruginosa The cells of the test strain cultured at 35 ° C. overnight on a normal agar slant medium are suspended in a sterilized phosphate buffer solution, and the number of bacteria per ml is adjusted to about 10 ^6. did. Staphylococcus aureus The cells of the test strain cultured overnight at 35 ° C. on a normal agar slant medium were suspended in sterilized 1/1000 normal broth, and the number of cells per ml was adjusted to about 10 ⁶ . (4) Test operation The specimen (about 30 mm × 20 mm) was inoculated with 0.2 ml of the number of bacteria, adhered to a polyethylene film, stored at 35 ° C., and stored at 1 hour, 3 hours, and 6 hours after the start of storage.
The viable cell count was washed out with a DLP medium (Nihon Pharmaceutical). The number of viable cells was measured by agar plate culture method (35 ° C., 2 days) using a culture medium for measuring the number of bacteria, and the sample 1
It was converted to the number of viable bacteria per sheet.

Further, the same amount of bacterial solution as that inoculated to the specimen was dispensed into a Petri dish and stored, and the number of viable bacteria was measured to serve as a control.

[0044]

[Table 2]

From the results shown in Tables 1 and 2, it is confirmed that the silicone rubber composition of the present invention has heat shrinkability and antibacterial properties even after a heating step.

[Example 3] 100 parts of a rubbery organopolysiloxane and 30 parts of a silica filler similar to those in Example 1 were mixed with 30 parts of powdered polyethylene (Flocene UF-4 (trade name, manufactured by Iron and Steel Chemical Co., Ltd., softening temperature: 101 ° C)). And 2 parts of antibacterial ceramic (trade name: VB-300N, containing 3% Ag, manufactured by Shinto Kogyo Co., Ltd.), and 2 parts of silicone oil paste of 2,4-dichlorobenzoyl peroxide (50%) as a crosslinking agent Was uniformly kneaded with two rolls, taken out as a sheet having a thickness of about 1 mm, and vulcanized in a hot-air dryer at 180 ° C. for 30 minutes to obtain a sheet. The obtained sheet was milky white and did not discolor.

A vulcanized sheet was obtained in the same manner as Comparative Example 2 except that no antibacterial ceramic was added.

With respect to the obtained vulcanized sheet, hardness, elongation, tensile strength, stretch holding ratio, and heat shrinkage were measured in the same manner as described above. Table 3 shows the results.

[0049]

[Table 3]

The antibacterial activity test of these sheets was measured as follows. Table 4 shows the results. <Test outline> Methicillin-resistant Staphylococcus aureus (MRS)
The bacterial solution of A) was inoculated on a sample (sample prepared to about 50 mm x 50 mm), and after tightly attaching a polyethylene film, it was stored at 35 ° C. At the start of storage, 1 hour, 3 hours,
The viable cell count after 6 hours and 24 hours was measured.

[0051]

[Table 4]

Example 4 The uncured compound of Example 2 was extruded into a tube by an extruder, and then heated and vulcanized (2).
(50 ° C.) to obtain a vulcanized tube having an outer diameter of 32 mm and an inner diameter of 29 mm. Next, this tube was 69 mm in inner diameter,
The tube was placed in a stainless steel pipe having a length of 5 m, heated to 150 ° C., air was sent into the tube at a pressure of 2 kg / cm ² to stretch the tube, and then cooled to room temperature in a pressurized state. The heat-shrinkable tube thus obtained has an inner diameter of 8 mm after stretching and 2 mm.
The inner diameter after heat shrinkage at 00 ° C. was 31 mm, showing sufficient heat shrinkability.

The tube before the heat shrinkage was shrunk to cover the doorknob and used for about one month in a normal room (place touched by hand), but no mold or other change in appearance was observed on the tube surface.

On the other hand, the doorknob coated with the tube similarly prepared with the uncured compound of Comparative Example 1 containing no antibacterial ceramics was conspicuous in appearance and showed a significant difference.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroshi Takei 1-10 Hitomi, Matsuida-cho, Usui-gun, Gunma Prefecture Inside Silicone Electronics Materials Research Laboratory Shin-Etsu Chemical Co., Ltd. (72) Inventor Masaki Mogi Chiyoda-ku, Tokyo 2-7-1, Shinmachi Chemical Industry Co., Ltd. (72) Inventor Mitsuo Ito 1780 Hirookagohara, Shiojiri City, Nagano Prefecture Matsumoto Dental University Research Institute for General Dentistry (56) References JP-A 47-14252 JP, A) JP-A-6-128383 (JP, A) JP-A-3-126741 (JP, A) JP-B-56-9182 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , (DB name) C08L 83/04 C08L 101/00 C08K 3/00 C08K 3/36

Claims (3)

(57) [Claims] (A) The following average composition formula (1): R ¹ _n SiO _{(4-n) / 2}
(1) (wherein, R ¹ represents the same or different unsubstituted or substituted monovalent hydrocarbon group, and n is an average number of 1.9 to 2.1) : 100 parts by weight, (B) organopolysiloxane resin or thermoplastic resin having a softening temperature in the range of 50 to 200 ° C: 5 to 100 parts by weight, (C) crosslinking agent and / or curing catalyst: curing component (A) (D) silver phosphate ceramics: a heat-shrinkable silicone rubber composition having antibacterial and antifungal properties, comprising 0.1 to 20 parts by weight as an essential component. 2. The heat-shrinkable silicone rubber composition according to claim 1, wherein the component (D) is a silver phosphate ceramic represented by the following composition formula (2). _{Ag-Ca u Zn v Al w} (PO 4) x (OH) y ... (2) ( where, wherein u, v, w, x, y are positive numbers.) 3. The method according to claim 1, further comprising:
3. The composition according to claim 1, wherein the composition is 100 parts by weight.