JP2023033596A - Molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molded product that comprises an elastomer layer having excellent sliding property.

SOLUTION: The molded product of the present embodiment is a molded product comprising an elastomer layer, and in which the surface roughness Ra on at least one surface side of the elastomer layer is 1.05 μm or more.

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to molded articles.

Various studies have so far been made on elastomers constituting molded articles. As this type of technology, for example, the technology described in Patent Document 1 is known. Patent Document 1 describes an elastomer having a smooth surface (claim 1 of Patent Document 1).

JP 2011-073148 A

However, as a result of examination by the present inventor, it was found that the elastomer described in Patent Document 1 has room for improvement in terms of slipperiness.

Upon further investigation by the present inventors, it was found that, even if the desired rubber properties were obtained in ordinary elastomers, the surface was formed to be smooth and slipperiness was often lowered.
As a result of further intensive research based on such findings, the present inventors have found that smoothness can be improved by imparting irregularities to the surface of the elastomer layer, and have completed the present invention.

According to the invention,
A molded article comprising an elastomer layer,
A molded article is provided in which at least one surface of the elastomer layer has a surface roughness Ra of 1.05 μm or more.

ADVANTAGE OF THE INVENTION According to this invention, the molded article provided with the elastomer layer excellent in slidability is provided.

FIG. 4 is a diagram for explaining a method of providing unevenness to the surface of an elastomer layer;

The molded article of this embodiment is provided with an elastomer layer.
In this molded article, at least one side of the elastomer layer has a surface roughness Ra of 1.05 μm or more.

According to the findings of the present inventors, it has been found that there is room for improvement in slipperiness since the surface of a typical elastomer layer is composed of a smooth surface having a surface roughness Ra of about 0.5 μm. On the other hand, it has been found that the smoothness can be improved by providing the surface of the elastomer layer with unevenness so that the surface roughness Ra is 1.05 μm or more.

According to this embodiment, it is possible to realize a molded product having an elastomer layer with excellent slipperiness.

Further, according to the findings of the present inventors, when a coating layer is formed by coating a slipping agent such as a silicone on the surface of the elastomer layer, the surface roughness Ra is set to 1.05 μm or more. It was newly discovered that the rubber properties such as elongation at break, tensile strength and hardness are reduced. Here, in order to improve lubrication, techniques for coating the surface of the elastomer with a silicone-based lubricant include paragraphs 0031 and 0048 described in JP-A-2017-165978.

As a result of examination based on the trade-off relationship between slipperiness and rubber properties, it was found that by physically imparting irregularities to the surface of the elastomer layer, while suppressing the deterioration of rubber properties, the slipperiness was improved. Turns out it can.
Although the detailed mechanism is not clear, the surface (exposed surface) can be moderately roughened without forming a coating layer made of a slipperiness-imparting agent, and the non-coating surface without the coating layer is formed. , it is considered that the slip property is improved without deteriorating the rubber properties.

In the molded product of this embodiment, the surface of the elastomer layer is an exposed surface having surface irregularities, and the surface roughness Ra of the elastomer layer is set to 1.05 μm or more.

According to this embodiment, it is possible to realize a molded product having an elastomer layer with excellent slipperiness and rubber properties.

The elastomer layer according to the present embodiment can have unevenness imparted (transferred) to the surface thereof during molding of the elastomer using, for example, an unevenness transfer film. That is, the surface unevenness can be imparted by transferring the surface unevenness of the unevenness transfer film to the surface of the elastomer layer.

Here, one example of a method for imparting irregularities to the surface of the elastomer layer will be described with reference to FIG. FIG. 1 shows a process cross-sectional view of press molding using a mold.

As shown in FIG. 1, a molding space is formed by combining an upper mold 10 and a lower mold 20 . Concave-convex transfer films 30 and 40 and elastomer 50 are arranged in this molding space. Then, by performing press molding under predetermined heating and pressurizing conditions, the surface profile (surface unevenness shape) on the surface 32 of the unevenness transfer film 30 is transferred to the surface 52 of the sheet-like elastomer 50 (elastomer layer). can do. At this time, the uneven surface shape of the unevenness transfer film 40 can be transferred to the opposite side of the elastomer 50 . It is also possible to form unevenness on the surface of the lower mold 20 and transfer it without using the unevenness transfer film 30 . Concave-convex transfer films 30 and 40 may be arranged on both sides of elastomer 50 , or concavo-convex transfer film 30 may be arranged on one side of elastomer 50 .

The molding method is not particularly limited, but compression molding, transfer molding, injection molding, and the like can be used, for example.

The concavo-convex transfer films 30 and 40 can be arranged so as to contact at least a portion or the entire surface of the elastomer 50 .
As the unevenness transfer films 30 and 40, for example, a resin sheet such as a matte film or sandpaper (sand mat), or a metal sheet having surface unevenness can be used. The concavo-convex transfer films 30 and 40 may be the same or different.

The matte film is a kneading type resin sheet in which particles are kneaded into a resin. On the other hand, the sandpaper (sand mat) is a resin sheet whose surface is subjected to a blasting treatment such as sand (silica sand) spraying to give fine unevenness to the film surface.

The material of the concavo-convex transfer film 30 is not particularly limited as long as it is a resin material having excellent releasability from the material of the elastomer 50 . For example, when the elastomer 50 is a silicone-based elastomer, polyester (PE), polyethylene terephthalate (PET), polyvinyl alcohol (PVA), or the like can be used as the resin material of the concavo-convex transfer film 30 . These may be used alone or in combination of two or more.

The matte film has a surface roughness Ra of, for example, 1.0 μm to 100 μm, preferably 2.0 μm to 50 μm. Also, the surface roughness of the sandpaper may be configured to be rougher than the surface roughness of the matte film. The mesh of the sandpaper is, for example, #100 to #10000, preferably #300 to #8000, and more preferably #500 to #5000.

When measured using the method for measuring the surface roughness Ra of the elastomer layer described later, the surface roughness Ra of the uneven transfer films 30 and 40 is, for example, 1.0 μm or more, preferably 1.5 μm or more, more preferably 1.5 μm or more. is 2.0 μm or more, more preferably 5.0 μm or more, and may be 100 μm or less, 50 μm or less, or 20 μm or less.
Alternatively, without using the uneven transfer films 30 and 40, the mold surface of the upper mold 10 or the lower mold 20 in contact with the elastomer 50 may be given a surface roughness Ra within such a numerical range. good.
However, the use of the concavo-convex transfer films 30 and 40 is superior in releasability, so that an elastomer layer with excellent production stability can be realized.

The elastomer 50 may be sheet-like, but may be molded into various shapes depending on the application. At this time, the texture transfer film 30 can be placed against the surface 52 of a suitable elastomer 50 .

The molded article having the elastomer layer can be used in various applications, and can be suitably used, for example, as a constituent member for medical equipment such as gaskets, automobile applications, and construction applications, or as a cushioning material during molding.

The elastomer layer according to this embodiment will be described in detail below.

First, the properties of the elastomer layer will be described.
The lower limit of the surface roughness Ra on the surface of the elastomer layer is, for example, 1.05 μm or more, preferably 2.0 μm or more, and more preferably 4.0 μm or more. Thereby, the slipperiness|lubricacy of an elastomer layer can be improved. On the other hand, the upper limit of the surface roughness Ra on the surface of the elastomer layer is, for example, 100 μm or less, preferably 50 μm or less, more preferably 30 μm or less. This makes it possible to maintain the mechanical hardness of the molding.

The surface roughness Ra of the elastomer layer is measured using a Keyence VK-9700 laser microscope under the conditions of lens: magnification of 20× and pitch: 0.2 μm. Subsequently, according to JIS B0601-2001 described in the analysis software VKanalyzer, the surface roughness Ra (μm) of the planar surface of the elastomer layer is measured under the condition of measuring area: 300 μm×300 μm.

The upper limit of the tack peak value TP on the surface of the elastomer layer is, for example, 4.0N or less, preferably 3.0N or less, more preferably 1.0N or less. By setting it to 4.0 N or less, the slip property can be improved to the extent that there is no practical problem. Further, by setting the index to 1.0 or less, it is possible to achieve good slipperiness even when the contact speed is high when the object to be touched is repeatedly contacted. On the other hand, the lower limit of the tack peak value TP is not particularly limited, but may be, for example, greater than 0N or 0.1N or more.

The procedure for measuring the tack peak value TP is as follows.
An aluminum probe having a flat surface with an area of 150 mm ² is measured under the conditions of probe moving speed: 2.3 mm / sec, probe crimping strength: 12 N, crimping time: 6 seconds. The flat surface of the aluminum probe is a measurement sample. The tack peak value on the surface of the elastomer layer was measured five times by a probe tack test when the surface of the elastomer layer was brought into contact and peeled off upward at a probe moving speed of 2.3 mm/sec. Let the average value of the measured values be the tack peak value TP.

The upper limit of the coefficient of dynamic friction on the surface of the elastomer layer is, for example, 2.0 or less, preferably 1.5 or less, and more preferably 1.0 or less. Thereby, the slipperiness|lubricacy of an elastomer layer can be improved. On the other hand, the lower limit of the coefficient of dynamic friction is not particularly limited, but may be, for example, greater than 0 or 0.1 or more.
In this embodiment, the coefficient of dynamic friction can be measured according to JIS K7125, and is the coefficient of dynamic friction with respect to polypropylene (PP), which is assumed to be applied to gaskets.

The lower limit of the elongation at break of the elastomer layer according to the present embodiment as measured according to JIS K6251 (2004) is, for example, 500% or more, preferably 700% or more, and more preferably 800%. That's it. Thereby, the high stretchability and durability of the molded article can be improved. On the other hand, the upper limit of the elongation at break of the elastomer layer is not particularly limited, but may be, for example, 2000% or less, 1800% or less, or 1500% or less. Thereby, the mechanical strength of the molded product can be improved.

The lower limit of the tear strength of the elastomer layer according to the present embodiment, measured according to JIS K6252 (2001), is, for example, 25 N/mm or more, preferably 30 N/mm or more, more preferably It is 33 N/mm or more, more preferably 35 N/mm or more. Thereby, the scratch resistance and mechanical strength of the molded product can be improved. In addition, the durability of the molded product can be improved during repeated use. On the other hand, the upper limit of the tear strength of the elastomer layer is not particularly limited, but may be, for example, 70 N/mm or less, or 60 N/mm or less. This allows the properties of the elastomer layer to be balanced.

The lower limit of the tensile strength of the elastomer layer according to the present embodiment measured according to JIS K6251 (2004) is, for example, 6.0 MPa or more, preferably 7.0 MPa or more, and more preferably It is 8.0 MPa or more. Thereby, the mechanical strength of the molded product can be improved. Also, the breaking energy can be increased. Therefore, it is possible to realize a molded article having excellent durability that can withstand repeated deformation. On the other hand, the upper limit of the tensile strength of the elastomer layer is not particularly limited, but may be, for example, 15 MPa or less, or 13 MPa or less. Thereby, the operability of the molded product can be improved.

The upper limit of the durometer hardness A defined in accordance with JIS K6253 (1997) of the elastomer layer according to the present embodiment is, for example, 40.0 or less, preferably 39.0 or less, and more preferably. is 38.0 or less, more preferably 35.0 or less. As a result, the flexibility of the molded product can be improved, and a molded product excellent in deformation easiness, which facilitates deformation such as bending and stretching, can be realized. Thereby, the operability of the molded product can be improved. The lower limit of the durometer hardness A of the elastomer layer is not particularly limited, but may be, for example, 1 or more, 5 or more, or 10 or more. Thereby, the mechanical strength of the molded product can be enhanced.

The upper limit of the tensile stress _M100 of the elastomer layer of the present embodiment when the elastomer layer is stretched 100% at 25°C, measured according to JIS K6251 (2004), is, for example, 3.0 MPa or less. , preferably 2.0 MPa or less, more preferably 1.5 MPa or less, and even more preferably 1.2 MPa or less. Thereby, the deformability of the elastomer can be improved. On the other hand, the lower limit of the tensile stress _M100 is not particularly limited, but may be 0.1 MPa or more, preferably 0.3 MPa or more. Thereby, the mechanical strength of the elastomer can be improved.

The upper limit of the tensile stress _M300 of the elastomer layer of the present embodiment when the elastomer layer is stretched 300% at 25° C., measured according to JIS K6251 (2004), is, for example, 5.0 MPa or less. , preferably 4.5 MPa or less, more preferably 4.0 MPa or less, and even more preferably 3.5 MPa or less. Thereby, the deformability of the elastomer can be improved. On the other hand, the lower limit of the tensile stress _M300 is not particularly limited, but may be 0.5 MPa or more, preferably 1.0 MPa or more. Thereby, the mechanical strength of the elastomer can be improved.

In the present embodiment, for example, the surface roughness can be reduced by appropriately selecting the type and amount of each component contained in the elastomer layer, the method of preparing the composition for forming the elastomer layer, the method of manufacturing the elastomer layer, and the like. It is possible to control the strength, tack peak value, dynamic friction coefficient, elongation at break, tensile strength, tear strength and hardness. Among these, for example, physically imparting unevenness to the elastomer layer, adjusting the surface roughness Ra of the unevenness transfer film, not forming a coating layer comprising a slipperiness imparting agent on the surface of the elastomer layer, Appropriately controlling the type and blending ratio of the resins that make up the layer, the crosslink density and crosslinked structure of the resin, improving the blending ratio of the inorganic filler and the dispersibility of the inorganic filler, etc., can reduce the surface roughness. , tack peak value, coefficient of dynamic friction, elongation at break, tensile strength, tear strength, and hardness within desired numerical ranges.

Next, the composition of the elastomer layer according to this embodiment will be described.

The elastomer constituting the elastomer layer is, for example, one selected from the group consisting of silicone rubber, fluororubber, nitrile rubber, acrylic rubber, styrene rubber, chloroprene rubber, ethylene propylene rubber, urethane rubber, isoprene rubber, and natural rubber. It can include the above. These may be used alone or in combination of two or more.

Among these, silicone rubber can be used from the viewpoint of the balance of rubber properties, chemical stability, and excellent thermal stability.

The thermosetting elastomer can be composed of a cured product of a curable elastomer composition. Moreover, the silicone rubber can be composed of a cured product of a silicone rubber-based curable composition.

Further, the elastomer of the present embodiment may be added with optional components capable of exhibiting various functions. For example, from the viewpoint of increasing mechanical strength, the elastomer can contain an inorganic filler. As the inorganic filler, known ones can be used, and for example, silica particles can be used.

A case where a silicone rubber-based curable composition is used as the silicone rubber, which is an example of the elastomer of the present embodiment, will be described below.

The silicone rubber-based curable composition of the present embodiment can contain a vinyl group-containing organopolysiloxane (A). The vinyl group-containing organopolysiloxane (A) is a polymer that is the main component of the silicone rubber-based curable composition of the present embodiment.

The vinyl group-containing organopolysiloxane (A) can contain a vinyl group-containing linear organopolysiloxane (A1) having a linear structure.

The vinyl group-containing linear organopolysiloxane (A1) has a linear structure and contains vinyl groups, and the vinyl groups serve as crosslinking points during curing.

The vinyl group content of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but for example, it preferably has two or more vinyl groups in the molecule and is 15 mol % or less. , 0.01 to 12 mol %. As a result, the amount of vinyl groups in the vinyl group-containing linear organopolysiloxane (A1) is optimized, and a network can be reliably formed with each component described later. In the present embodiment, "~" means including both numerical values.

In the present specification, the vinyl group content is the mol % of the vinyl group-containing siloxane units when the total units constituting the vinyl group-containing linear organopolysiloxane (A1) are taken as 100 mol %. . However, one vinyl group is considered to be one vinyl group-containing siloxane unit.

The degree of polymerization of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is, for example, preferably in the range of about 1,000 to 10,000, more preferably in the range of about 2,000 to 5,000. The degree of polymerization can be determined, for example, as a polystyrene-equivalent number-average polymerization degree (or number-average molecular weight) in GPC (gel permeation chromatography) using chloroform as a developing solvent.

Furthermore, the specific gravity of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is preferably in the range of about 0.9 to 1.1.

As the vinyl group-containing linear organopolysiloxane (A1), the heat resistance, flame retardancy, chemical stability, etc. of the resulting silicone rubber can be improved by using those having the degree of polymerization and specific gravity within the ranges described above. can be improved.

As the vinyl group-containing linear organopolysiloxane (A1), those having a structure represented by the following formula (1) are particularly preferred.

In formula (1), R ¹ is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, or a hydrocarbon group of a combination thereof having 1 to 10 carbon atoms. The alkyl group having 1 to 10 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferred. The alkenyl group having 1 to 10 carbon atoms includes, for example, vinyl group, allyl group, butenyl group, etc. Among them, vinyl group is preferred. The aryl group having 1 to 10 carbon atoms includes, for example, a phenyl group.

R ² is a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 to 10 carbon atoms, or a hydrocarbon group combining these. The alkyl group having 1 to 10 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferable. Examples of alkenyl groups having 1 to 10 carbon atoms include vinyl groups, allyl groups and butenyl groups. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

R ³ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group combining these. The alkyl group having 1 to 8 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferred. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group.

Furthermore, examples of substituents for R ¹ and R ² in formula (1) include methyl group and vinyl group, and examples of substituents for R ³ include methyl group.

In formula (1), a plurality of R ¹ are independent of each other and may be different or the same. Furthermore, the same applies to R ² and R ³ .

Furthermore, m and n are the numbers of repeating units constituting the vinyl group-containing linear organopolysiloxane (A1) represented by formula (1), m is an integer of 0 to 2000, and n is 1000 to 10000. is an integer of m is preferably 0-1000 and n is preferably 2000-5000.

Further, specific structures of the vinyl group-containing linear organopolysiloxane (A1) represented by formula (1) include, for example, those represented by the following formula (1-1).

In formula (1-1), R ¹ and R ² are each independently a methyl group or a vinyl group, and at least one is a vinyl group.

Furthermore, as the vinyl group-containing linear organopolysiloxane (A1), a first vinyl group-containing vinyl group having a vinyl group content of 2 or more vinyl groups in the molecule and not more than 0.4 mol% It contains a linear organopolysiloxane (A1-1) and a second vinyl group-containing linear organopolysiloxane (A1-2) having a vinyl group content of 0.5 to 15 mol%. It is preferable to have As crude rubber, which is a raw material of silicone rubber, a first vinyl group-containing linear organopolysiloxane (A1-1) having a general vinyl group content and a second vinyl group-containing linear organopolysiloxane having a high vinyl group content were used. By combining with the chain organopolysiloxane (A1-2), the vinyl groups can be unevenly distributed, and the crosslink density can be more effectively formed in the crosslink network of the silicone rubber. As a result, the tear strength of silicone rubber can be increased more effectively.

Specifically, as the vinyl group-containing linear organopolysiloxane (A1), for example, a unit in which R ¹ is a vinyl group and/or a unit in which R ² is a vinyl group in the above formula (1-1) , a first vinyl group-containing linear organopolysiloxane (A1-1) having 2 or more in the molecule and containing 0.4 mol% or less, and a unit in which R ¹ is a vinyl group and / or R It is preferable to use a second vinyl group-containing linear organopolysiloxane (A1-2) containing 0.5 to 15 mol % of units in which ² is a vinyl group.

The first vinyl group-containing linear organopolysiloxane (A1-1) preferably has a vinyl group content of 0.01 to 0.2 mol %. The second vinyl group-containing linear organopolysiloxane (A1-2) preferably has a vinyl group content of 0.8 to 12 mol %.

Furthermore, when combining the first vinyl group-containing linear organopolysiloxane (A1-1) and the second vinyl group-containing linear organopolysiloxane (A1-2), (A1-1) and (A1-2) is not particularly limited, but for example, the weight ratio of (A1-1):(A1-2) is preferably 50:50 to 95:5, and 80:20 to 90: 10 is more preferred.

The first and second vinyl group-containing linear organopolysiloxanes (A1-1) and (A1-2) may be used singly or in combination of two or more. good.

Also, the vinyl group-containing organopolysiloxane (A) may contain a vinyl group-containing branched organopolysiloxane (A2) having a branched structure.

<<Organohydrogenpolysiloxane (B)>>
The silicone rubber-based curable composition of the present embodiment can contain an organohydrogenpolysiloxane (B).
Organohydrogenpolysiloxane (B) is classified into linear organohydrogenpolysiloxane (B1) having a linear structure and branched organohydrogenpolysiloxane (B2) having a branched structure. Either or both may be included.

The linear organohydrogenpolysiloxane (B1) has a linear structure and a structure (≡Si—H) in which hydrogen is directly bonded to Si, and is the vinyl group-containing organopolysiloxane (A). It is a polymer that undergoes a hydrosilylation reaction with other vinyl groups and other vinyl groups contained in other components of the silicone rubber-based curable composition to crosslink these components.

The molecular weight of the linear organohydrogenpolysiloxane (B1) is not particularly limited.

The weight average molecular weight of the linear organohydrogenpolysiloxane (B1) can be measured, for example, by polystyrene conversion in GPC (gel permeation chromatography) using chloroform as a developing solvent.

Also, the straight-chain organohydrogenpolysiloxane (B1) generally preferably does not have a vinyl group. Thereby, it is possible to accurately prevent the progress of the cross-linking reaction in the molecule of the linear organohydrogenpolysiloxane (B1).

As the linear organohydrogenpolysiloxane (B1) as described above, for example, one having a structure represented by the following formula (2) is preferably used.

In formula (2), R ⁴ is a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 to 10 carbon atoms, a hydrocarbon group combining these groups, or a hydride group. The alkyl group having 1 to 10 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferred. Examples of alkenyl groups having 1 to 10 carbon atoms include vinyl groups, allyl groups and butenyl groups. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

R ⁵ is a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 to 10 carbon atoms, a hydrocarbon group combining these, or a hydride group. Examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group and propyl group, with methyl group being preferred. Examples of alkenyl groups having 1 to 10 carbon atoms include vinyl groups, allyl groups and butenyl groups. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

In formula (2), a plurality of R ⁴ are independent of each other and may be different from each other or may be the same. The same is true for ^R5 . However, at least two or more of the plurality of R ⁴ and R ⁵ are hydride groups.

R ⁶ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group combining these. The alkyl group having 1 to 8 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferred. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group. A plurality of R ⁶ are independent from each other and may be different from each other or may be the same.

Examples of substituents for R ⁴ , R ⁵ and R ⁶ in formula (2) include methyl group and vinyl group, and methyl group is preferred from the viewpoint of preventing intramolecular cross-linking reaction.

Further, m and n are the numbers of repeating units constituting the linear organohydrogenpolysiloxane (B1) represented by formula (2), m is an integer of 2 to 150, and n is an integer of 2 to 150. is. Preferably, m is an integer from 2-100 and n is an integer from 2-100.

In addition, linear organohydrogenpolysiloxane (B1) may be used individually by 1 type, and may be used in combination of 2 or more types.

Since the branched organohydrogenpolysiloxane (B2) has a branched structure, it is a component that forms regions with a high crosslink density and greatly contributes to the formation of a loose and dense crosslink density structure in the silicone rubber system. Further, like the linear organohydrogenpolysiloxane (B1), it has a structure (≡Si—H) in which hydrogen is directly bonded to Si, and in addition to the vinyl group of the vinyl group-containing organopolysiloxane (A), silicone It is a polymer that undergoes a hydrosilylation reaction with the vinyl groups of the components blended in the rubber-based curable composition to crosslink these components.

Further, the branched organohydrogenpolysiloxane (B2) has a specific gravity in the range of 0.9 to 0.95.

Furthermore, it is generally preferred that the branched organohydrogenpolysiloxane (B2) does not have a vinyl group. Thereby, it is possible to accurately prevent the progress of the cross-linking reaction in the molecule of the branched organohydrogenpolysiloxane (B2).

As the branched organohydrogenpolysiloxane (B2), those represented by the following average compositional formula (c) are preferred.

Average composition formula (c)
(H _a (R ⁷ ) _3-a SiO _1/2 ) _m (SiO _4/2 ) _n
(In formula (c), R ⁷ is a monovalent organic group, a is an integer ranging from 1 to 3, m is the number of H _a (R ⁷ ) _3-a SiO _1/2 units, n is SiO _4/ is a number of ₂ units)

In formula (c), R ⁷ is a monovalent organic group, preferably a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an aryl group, or a hydrocarbon group combining these. The alkyl group having 1 to 10 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferable. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

In formula (c), a is the number of hydride groups (hydrogen atoms directly bonded to Si) and is an integer in the range of 1-3, preferably 1.

In formula (c), m is the number of H _a (R ⁷ ) _3-a SiO _1/2 units, and n is the number of SiO _4/2 units.

The branched organohydrogenpolysiloxane (B2) has a branched structure. The linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) differ in that their structures are linear or branched. The number of bound alkyl groups R (R/Si) is 1.8 to 2.1 for the linear organohydrogenpolysiloxane (B1) and 0.8 to 1 for the branched organohydrogenpolysiloxane (B2). .7 range.

Since the branched organohydrogenpolysiloxane (B2) has a branched structure, for example, when heated to 1000° C. at a heating rate of 10° C./min in a nitrogen atmosphere, the residual amount is 5% or more. becomes. On the other hand, since the straight-chain organohydrogenpolysiloxane (B1) is straight-chain, the amount of residue after heating under the above conditions is almost zero.

Specific examples of the branched organohydrogenpolysiloxane (B2) include those having a structure represented by the following formula (3).

In formula (3), R ⁷ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, a hydrocarbon group combining these, or a hydrogen atom. The alkyl group having 1 to 8 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferred. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group. Examples of the substituent of ^R7 include a methyl group and the like.

In formula (3), a plurality of R ⁷ are independent of each other and may be different from each other or may be the same.

In formula (3), "--O--Si.ident." represents that Si has a branched structure extending three-dimensionally.

The branched organohydrogenpolysiloxane (B2) may be used alone or in combination of two or more.

Moreover, in the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2), the amount of hydrogen atoms (hydride groups) directly bonded to Si is not particularly limited. However, in the silicone rubber-based curable composition, linear organohydrogenpolysiloxane (B1) and branched organohydrogenpolysiloxane are The total amount of hydride groups in the siloxane (B2) is preferably from 0.5 to 5 mol, more preferably from 1 to 3.5 mol. As a result, a crosslinked network is reliably formed between the linear organohydrogenpolysiloxane (B1), the branched organohydrogenpolysiloxane (B2), and the vinyl group-containing linear organopolysiloxane (A1). can be made

<<Silica particles (C)>>
The silicone rubber-based curable composition of the present embodiment can contain silica particles (C).

Silica particles (C) are not particularly limited, but for example, fumed silica, pyrogenic silica, precipitated silica and the like are used. These may be used alone or in combination of two or more.

The silica particles (C) preferably have a BET specific surface area of, for example, 50 to 400 m ² /g, more preferably 100 to 400 m ² /g. Also, the average primary particle size is preferably, for example, 1 to 100 nm, more preferably about 5 to 20 nm.

By using silica particles (C) having a specific surface area and an average particle size within the above ranges, the hardness and mechanical strength of the silicone rubber formed can be improved, particularly the tensile strength can be improved.

<<Silane coupling agent (D)>>
The silicone rubber-based curable composition of the present embodiment can contain a silane coupling agent (D).
Silane coupling agent (D) can have a hydrolyzable group. The hydrolyzable group is hydrolyzed with water to form a hydroxyl group, and the hydroxyl group undergoes a dehydration condensation reaction with the hydroxyl group on the surface of the silica particle (C), thereby modifying the surface of the silica particle (C).

Moreover, this silane coupling agent (D) can contain a silane coupling agent having a hydrophobic group. As a result, the hydrophobic group is imparted to the surface of the silica particles (C), so that the cohesive force of the silica particles (C) in the silicone rubber-based curable composition and further in the silicone rubber is reduced (hydrogen aggregation due to bonding is reduced), and as a result, it is presumed that the dispersibility of the silica particles in the silicone rubber-based curable composition is improved. This increases the interface between the silica particles and the rubber matrix, increasing the reinforcing effect of the silica particles. Furthermore, it is presumed that the slipperiness of the silica particles in the matrix is improved when the rubber matrix is deformed. The improved dispersibility and slipperiness of the silica particles (C) improve the mechanical strength (for example, tensile strength and tear strength) of the silicone rubber due to the silica particles (C).

Furthermore, the silane coupling agent (D) can contain a silane coupling agent having a vinyl group. As a result, vinyl groups are introduced onto the surfaces of the silica particles (C). Therefore, during curing of the silicone rubber-based curable composition, that is, a hydrosilylation reaction occurs between the vinyl group of the vinyl group-containing organopolysiloxane (A) and the hydride group of the organohydrogenpolysiloxane (B). , When a network (crosslinked structure) is formed by these, the vinyl groups possessed by the silica particles (C) also participate in the hydrosilylation reaction with the hydride groups possessed by the organohydrogenpolysiloxane (B). Silica particles (C) also come to be taken in. As a result, it is possible to reduce the hardness and increase the modulus of the formed silicone rubber.

As the silane coupling agent (D), a silane coupling agent having a hydrophobic group and a silane coupling agent having a vinyl group can be used in combination.

Examples of the silane coupling agent (D) include those represented by the following formula (4).

_Yn -Si-(X) _4-n (4)
In the above formula (4), n represents an integer of 1-3. Y represents a functional group having a hydrophobic group, a hydrophilic group or a vinyl group, and when n is 1 it is a hydrophobic group, and when n is 2 or 3 at least one of It is a hydrophobic group. X represents a hydrolyzable group.

The hydrophobic group is an alkyl group having 1 to 6 carbon atoms, an aryl group, or a hydrocarbon group having a combination thereof, and examples thereof include a methyl group, an ethyl group, a propyl group, a phenyl group, and the like. Methyl groups are preferred.

Moreover, the hydrophilic group includes, for example, a hydroxyl group, a sulfonic acid group, a carboxyl group, a carbonyl group, etc. Among them, a hydroxyl group is particularly preferable. The hydrophilic group may be contained as a functional group, but is preferably not contained from the viewpoint of imparting hydrophobicity to the silane coupling agent (D).

Further, the hydrolyzable group includes an alkoxy group such as a methoxy group and an ethoxy group, a chloro group, a silazane group, and the like. Among them, a silazane group is preferable because of its high reactivity with the silica particles (C). A compound having a silazane group as a hydrolyzable group has two structures of (Y _n —Si—) in the above formula (4) due to its structural characteristics.

Specific examples of the silane coupling agent (D) represented by the above formula (4) include, for example, those having a hydrophobic group as a functional group, such as methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane, Alkoxysilanes such as ethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane; methyltrichlorosilane; chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane; hexamethyldisilazane; alkoxysilanes such as propylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane, vinylmethyldichlorosilane; Among them, hexamethyldisilazane is particularly preferable as one having a hydrophobic group, and divinyltetramethyldisilazane as one having a vinyl group, in view of the above description.

<<platinum or platinum compound (E)>>
The silicone rubber-based curable composition of this embodiment can contain platinum or a platinum compound (E).
Platinum or a platinum compound (E) is a catalytic component that acts as a catalyst during curing. The amount of platinum or platinum compound (E) added is a catalytic amount.

As the platinum or platinum compound (E), a known one can be used, for example, platinum black, platinum supported on silica or carbon black, chloroplatinic acid or an alcohol solution of chloroplatinic acid, A complex salt of platinic acid and olefin, a complex salt of chloroplatinic acid and vinyl siloxane, and the like are included.

In addition, platinum or a platinum compound (E) may be used individually by 1 type, and may be used in combination of 2 or more type.

<<Water (F)>>
Further, the silicone rubber-based curable composition of the present embodiment may contain water (F) in addition to the above components (A) to (E).

Water (F) is a component that functions as a dispersion medium for dispersing each component contained in the silicone rubber-based curable composition and contributes to the reaction between the silica particles (C) and the silane coupling agent (D). . Therefore, the silica particles (C) and the silane coupling agent (D) can be linked to each other more reliably in the silicone rubber, and uniform properties can be exhibited as a whole.

Furthermore, the silicone rubber-based curable composition of the present embodiment may contain, in addition to the above components (A) to (F), known additive components blended in silicone rubber-based curable compositions. Examples thereof include diatomaceous earth, iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide, cerium oxide, calcium carbonate, magnesium carbonate, zinc carbonate, glass wool, and mica. In addition, dispersants, pigments, dyes, antistatic agents, antioxidants, flame retardants, thermal conductivity improvers and the like can be added as appropriate.

In addition, although the content ratio of each component in the silicone rubber-based curable composition is not particularly limited, it is set as follows, for example.

In the present embodiment, the upper limit of the content of the silica particles (C) may be, for example, 60 parts by weight or less, preferably 50 parts by weight, with respect to 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A). It may be 35 parts by weight or less, more preferably 35 parts by weight or less. This makes it possible to achieve a good balance between tear strength and permanent tensile strain. Moreover, the lower limit of the content of the silica particles (C) is not particularly limited to 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A), but may be, for example, 20 parts by weight or more.

The silane coupling agent (D) preferably contains, for example, 5 parts by weight or more and 100 parts by weight or less of the silane coupling agent (D) with respect to 100 parts by weight of the vinyl group-containing organopolysiloxane (A). , more preferably 5 parts by weight or more and 40 parts by weight or less.
Thereby, the dispersibility of the silica particles (C) in the silicone rubber-based curable composition can be reliably improved.

The content of the organohydrogenpolysiloxane (B) is specifically based on 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A), the silica particles (C) and the silane coupling agent (D), for example , preferably 0.5 to 20 parts by weight, more preferably 0.8 to 15 parts by weight. When the content of (B) is within the above range, a more effective curing reaction may be possible.

The content of platinum or platinum compound (E) means the amount of catalyst and can be set as appropriate. Specifically, vinyl group-containing organopolysiloxane (A), silica particles (C), silane coupling agent ( The amount of the platinum group metal in this component is 0.01 to 1000 ppm by weight, preferably 0.1 to 500 ppm, based on the total amount of D). By setting the content of platinum or platinum compound (E) to the above lower limit or more, the resulting silicone rubber composition can be sufficiently cured. By setting the content of platinum or platinum compound (E) to the above upper limit or less, the curing speed of the obtained silicone rubber composition can be improved.

Furthermore, when water (F) is contained, the content thereof can be appropriately set, but specifically, for 100 parts by weight of the silane coupling agent (D), for example, 10 to 100 parts by weight. and more preferably 30 to 70 parts by weight. This allows the reaction between the silane coupling agent (D) and the silica particles (C) to proceed more reliably.

<Method for producing silicone rubber>
Next, a method for producing the silicone rubber of this embodiment will be described.
As a method for producing the silicone rubber of the present embodiment, the silicone rubber can be obtained by preparing a silicone rubber-based curable composition and curing the silicone rubber-based curable composition.
Details will be described below.

First, each component of the silicone rubber-based curable composition is uniformly mixed using any kneading device to prepare the silicone rubber-based curable composition.

[1] For example, a vinyl group-containing organopolysiloxane (A), silica particles (C), and a silane coupling agent (D) are weighed in predetermined amounts, and then kneaded with an arbitrary kneading device, A kneaded material containing these components (A), (C) and (D) is obtained.

The kneaded product is preferably obtained by previously kneading the vinyl group-containing organopolysiloxane (A) and the silane coupling agent (D), and then kneading (mixing) the silica particles (C). This further improves the dispersibility of the silica particles (C) in the vinyl group-containing organopolysiloxane (A).

Further, when obtaining this kneaded product, water (F) may be added to the kneaded product of each component (A), (C), and (D), if necessary. This allows the reaction between the silane coupling agent (D) and the silica particles (C) to proceed more reliably.

Further, the kneading of the components (A), (C) and (D) is preferably carried out through a first step of heating at a first temperature and a second step of heating at a second temperature. As a result, in the first step, the surface of the silica particles (C) can be surface-treated with the coupling agent (D), and in the second step, the silica particles (C) and the coupling agent (D) By-products generated in the reaction can be reliably removed from the kneaded material. After that, if necessary, the component (A) may be added to the obtained kneaded product and further kneaded. This can improve the familiarity of the components of the kneaded product.

The first temperature is preferably, for example, about 40 to 120.degree. C., and more preferably, for example, about 60 to 90.degree. The second temperature is, for example, preferably about 130 to 210.degree. C., more preferably about 160 to 180.degree.

Moreover, the atmosphere in the first step is preferably an inert atmosphere such as a nitrogen atmosphere, and the atmosphere in the second step is preferably a reduced-pressure atmosphere.

Furthermore, the time for the first step is preferably, for example, about 0.3 to 1.5 hours, more preferably about 0.5 to 1.2 hours. The time for the second step is, for example, preferably about 0.7 to 3.0 hours, more preferably about 1.0 to 2.0 hours.

By setting the first step and the second step under the above conditions, the above effect can be obtained more significantly.

[2] Next, the organohydrogenpolysiloxane (B) and the platinum or platinum compound (E) are weighed in predetermined amounts, and then the kneaded product prepared in the above step [1] using any kneading device. Then, the respective components (B) and (E) are kneaded to obtain a silicone rubber-based curable composition. The obtained silicone rubber-based curable composition may be a paste containing a solvent.

When kneading the components (B) and (E), the kneaded product previously prepared in the above step [1] and the organohydrogenpolysiloxane (B) were prepared in the above step [1]. It is preferable to knead the kneaded material with platinum or the platinum compound (E), and then knead the respective kneaded materials. This ensures that each component (A) to (E) is contained in the silicone rubber-based curable composition without allowing the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) to proceed. can be distributed in

The temperature at which the respective components (B) and (E) are kneaded is preferably, for example, about 10 to 70°C, more preferably about 25 to 30°C, as the set temperature of the rolls.

Further, the kneading time is preferably about 5 minutes to 1 hour, more preferably about 10 to 40 minutes.

In the steps [1] and [2], the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) proceeds more accurately by setting the temperature within the above range. can be prevented or suppressed; In addition, by setting the kneading time within the above range in steps [1] and [2], each component (A) to (E) can be more reliably dispersed in the silicone rubber-based curable composition. can be done.

The kneading device used in steps [1] and [2] is not particularly limited, but for example, a kneader, two rolls, a Banbury mixer (continuous kneader), a pressure kneader, etc. can be used.

In step [2], a reaction inhibitor such as 1-ethynylcyclohexanol may be added to the kneaded product. As a result, even if the temperature of the kneaded product is set to a relatively high temperature, the progress of the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) can be more accurately prevented or suppressed. be able to.

[3] Next, a silicone rubber is formed by curing the silicone rubber-based curable composition.

In the present embodiment, the curing step of the silicone rubber-based curable resin composition includes, for example, heating at 100 to 250° C. for 1 to 30 minutes (primary curing), followed by post-baking at 200° C. for 1 to 4 hours (secondary curing). curing).
The silicone rubber of the present embodiment is obtained through the steps described above.

As a result of examination by the present inventor, the following findings were obtained. It was found that if the amount of filler in silicone rubber is reduced, the hardness and tensile stress can be reduced, but on the other hand, the tear strength is lowered and the durability of the silicone rubber is lowered.

Therefore, as a result of intensive studies, by appropriately selecting a resin composition such as a vinyl group-containing organopolysiloxane (A), it is possible to control the uneven distribution of cross-linking density and cross-linking structure, and to achieve low stress and low hardness in a wide strain range. It was found that the tear strength of the silicone rubber can be increased while realizing this. Moreover, it turned out that the tensile strength of silicone rubber can also be improved. Although the detailed mechanism is not clear, the combination of high-vinyl group-containing organopolysiloxane and low-vinyl group-containing organopolysiloxane makes it possible to control uneven distribution of the crosslinked structure, thereby increasing the tear strength of silicone rubber while reducing hardness. It is considered possible. Thus, by increasing the tear strength while maintaining other physical properties, the breaking energy of the silicone rubber can be increased.

Further, in the present embodiment, for example, by reducing the amount of filler, the tensile stress in the initial strain is reduced, but by controlling the crosslink density of the resin and the uneven distribution of the crosslinked structure, the tensile stress in the late strain can be reduced.

In the present embodiment, for example, by appropriately selecting the type and amount of each component contained in the silicone rubber-based curable composition, the preparation method of the silicone rubber-based curable composition, the production method of the silicone rubber, etc., It is possible to control the tensile stress, breaking energy, tensile strength, tear strength and hardness. Among these, for example, a combination of a low vinyl group-containing linear organopolysiloxane (A1-1) and a high vinyl group-containing linear organopolysiloxane (A1-2), a vinyl group having a terminal vinyl group By using the group-containing organopolysiloxane (A), the crosslink density of the resin and the uneven distribution of the crosslinked structure are controlled, and the addition timing of the vinyl group-containing organopolysiloxane (A) and the blending ratio of the silica particles (C) are controlled. , modifying the surface of the silica particles (C) with the silane coupling agent (D), adding water, etc. to more reliably proceed the reaction between the silane coupling agent (D) and the silica particles (C). These factors are factors for setting the tensile stress, energy at break, tensile strength, tear strength, and hardness within desired numerical ranges.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than those described above can also be adopted.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to the description of these Examples.

Raw material components used in Examples and Comparative Examples are shown below.
(Vinyl group-containing organopolysiloxane (A))
Low-vinyl group-containing linear organopolysiloxane (A1-1): a vinyl group-containing dimethylpolysiloxane synthesized according to Synthesis Scheme 1 (structure represented by formula (1-1) where only R ¹ (terminal) is a vinyl group structure that is
High-vinyl group-containing linear organopolysiloxane (A1-2): a vinyl group-containing dimethylpolysiloxane synthesized according to Synthesis Scheme 2 (a structure represented by formula (1-1) in which R ¹ and R ² are vinyl groups; some structure)

(Organohydrogenpolysiloxane (B))
- Organohydrogenpolysiloxane (B): "TC-25D" manufactured by Momentive
(Silica particles (C))
・Silica particles (C): Silica fine particles (particle diameter 7 nm, specific surface area 300 m ² /g), manufactured by Nippon Aerosil Co., Ltd., "AEROSIL 300"
(Silane coupling agent (D))
- Silane coupling agent (D-1): Hexamethyldisilazane (HMDZ), manufactured by Gelst, "HEXAMETHYLDISILAZANE (SIH6110.1)"
- Silane coupling agent (D-2): divinyltetramethyldisilazane, manufactured by Gelst, "1,3-DIVINYLTETRAMETHYLDISILAZANE (SID4612.0)"
(Platinum or platinum compound (E))
・ Platinum or platinum compound (E): platinum compound, manufactured by Momentive, "TC-25A"

(Synthesis of vinyl group-containing organopolysiloxane (A))
[Synthesis Scheme 1: Synthesis of Low Vinyl Group-Containing Linear Organopolysiloxane (A1-1)]
A low vinyl group-containing linear organopolysiloxane (A1-1) was synthesized according to the following formula (5).
That is, 74.7 g (252 mmol) of octamethylcyclotetrasiloxane and 0.1 g of potassium siliconate were placed in a 300 mL separable flask having a cooling tube and a stirring blade, which was replaced with Ar gas, and the temperature was raised to 120° C. for 30 minutes. Stirred. At this time, an increase in viscosity was confirmed.
After that, the temperature was raised to 155° C. and stirring was continued for 3 hours. After 3 hours, 0.1 g (0.6 mmol) of 1,3-divinyltetramethyldisiloxane was added, and the mixture was further stirred at 155° C. for 4 hours.
Furthermore, after 4 hours, it was diluted with 250 mL of toluene and then washed with water three times. The washed organic layer was washed several times with 1.5 L of methanol for reprecipitation purification to separate the oligomer and polymer. The obtained polymer was dried overnight under reduced pressure at 60° C. to obtain a low-vinyl group-containing linear organopolysiloxane (A1-1) (Mn=2,2×10 ⁵ , Mw=4,8×10 ⁵ ). Also, the vinyl group content calculated by H-NMR spectrum measurement was 0.04 mol %.

[Synthesis Scheme 2: Synthesis of High Vinyl Group-Containing Linear Organopolysiloxane (A1-2)]
In the above synthesis step (A1-1), in addition to 74.7 g (252 mmol) of octamethylcyclotetrasiloxane, 0.5 g of 2,4,6,8-tetramethyl 2,4,6,8-tetravinylcyclotetrasiloxane was added. Except for using 86 g (2.5 mmol), the same synthesis step as in (A1-1) was performed to obtain a high-vinyl group-containing linear organopolysiloxane (A1- 2) was synthesized. (Mn=2,3×10 ⁵ , Mw=5,0×10 ⁵ ). Also, the vinyl group content calculated by H-NMR spectrum measurement was 0.93 mol %.

(Preparation of silicone rubber-based curable composition)
A silicone rubber-based curable composition was prepared as follows. First, a mixture of 95% vinyl group-containing organopolysiloxane (A), silane coupling agent (D) and water (F) is pre-kneaded in the proportions shown in Table 1, and then silica particles (C) are added to the mixture. was added and further kneaded to obtain a kneaded product (silicone rubber compound).
Here, the kneading after the addition of the silica particles (C) includes a first step of kneading for 1 hour under a nitrogen atmosphere at 60 to 90° C. for the coupling reaction, and removal of the by-product (ammonia). For this purpose, a second step of kneading for 2 hours under a reduced pressure atmosphere at 160 to 180 ° C. is performed, followed by cooling, and the remaining 5% of the vinyl group-containing organopolysiloxane (A) is added twice. Add in portions and knead for 20 minutes.
Subsequently, 2.6 parts by weight of organohydrogenpolysiloxane (B) and 0.5 parts by weight of platinum or a platinum compound (E) were added to 100 parts by weight of the resulting kneaded product (silicone rubber compound), followed by rolling. to obtain a silicone rubber-based curable composition.

[Comparative Example 1]
(Preparation of "sheet-shaped silicone rubber")
The obtained silicone rubber-based curable composition was pressed at 170° C. and 10 MPa for 10 minutes to form a sheet having a thickness of 1 mm, and was subjected to primary curing. Subsequently, the composition was heated at 200° C. for 4 hours for secondary curing to obtain a sheet-like silicone rubber (cured product of silicone rubber-based curable composition). As Comparative Example 1, the obtained "sheet-shaped silicone rubber" was used as it was.

[Examples 1 to 11]
(Preparation of "sheet-shaped silicone rubber" having uneven surface)
First, as shown in FIG. 1, in the molding space between the upper mold 10 and the lower mold 20, the obtained silicone rubber-based curable composition is applied to the unevenness transfer films 30 and 40 (the unevenness transfer films shown in Table 2). It was placed so as to be sandwiched between the uneven surfaces (surfaces with rough surfaces). Subsequently, the same heating and pressurizing conditions as in Comparative Example 1, that is, pressing at 170 ° C. and 10 MPa for 10 minutes, molding into a sheet with a thickness of 1 mm, primary curing, followed by heating at 200 ° C. for 4 hours Then, secondary curing was performed to obtain a sheet-like silicone rubber (cured product of silicone rubber-based curable composition). The unevenness transfer films 30 and 40 were separated from the surface of the resulting sheet-shaped silicone rubber (elastomer 50) to obtain a "sheet-shaped silicone rubber" having unevenness on the surface.

The surface roughness Ra (μm) on the uneven surface of the uneven surface of the uneven transfer film in Table 2 was measured by the same method as the surface roughness Ra described later.

The sheet-shaped silicone rubbers (hereinafter referred to as "elastomer layers") obtained in Comparative Examples and Examples were evaluated based on the following evaluation items.

(Surface roughness Ra)
The surface roughness Ra of the obtained elastomer layer was measured using a Keyence VK-9700 laser microscope under the conditions of lens: magnification of 20× and pitch: 0.2 μm. Subsequently, according to JIS B0601-2001 described in the analysis software VKanalyzer, the surface roughness Ra (μm) on the surface of the elastomer layer was measured under the condition of measuring area: 300 μm×300 μm. Table 3 shows the evaluation results.

(Tack peak value)
The tack peak value was measured using a tackiness checker manufactured by Toyo Seiki Co., Ltd. as a measuring device. As the measurement mode, Constant Load was used, in which the probe was pushed to a set pressure value, and control was continued so that the pressure value was maintained until the set time passed.
Specifically, an aluminum probe having a flat surface with an area of 150 mm ² was moved at a probe moving speed of 2.3 mm / sec, a probe crimping strength of 12 N, and a crimping time of 6 seconds. is brought into contact with the surface of the measurement sample (obtained elastomer layer) and peeled upward at a probe moving speed of 2.3 mm/sec. The tack peak value TP(N) was taken as the average value of the five measurements. Table 3 shows the evaluation results.

(dynamic friction coefficient)
The coefficient of dynamic friction on the surface of the obtained elastomer layer was measured according to JIS K7125 with respect to PP assumed to be applied to gaskets. Table 3 shows the evaluation results.

(Hardness: durometer hardness A)
Six of the obtained elastomer layers with a thickness of 1 mm were laminated to prepare a test piece of 6 mm. Type A durometer hardness was measured on the obtained test piece in accordance with JIS K6253 (1997). Two samples were used, each sample was measured with n=5, and the average value of 10 measurements was taken as the measured value. Table 3 shows the evaluation results.

(Tear strength)
A crescent-shaped test piece was prepared according to JIS K6252 (2001) using the obtained elastomer layer with a thickness of 1 mm, and the tear strength at 25°C of the obtained crescent-shaped test piece was measured. The unit is N/mm. Five samples were used, and the five average values were used as the measured values. Table 3 shows the evaluation results.

(tensile strength)
Using the obtained elastomer layer with a thickness of 1 mm, a dumbbell-shaped No. 3 test piece was produced according to JIS K6251 (2004), and the tensile strength of the obtained test piece at 25°C was measured. The unit is MPa. Three samples were used, and the average value of the three values was used as the measured value.

(tensile stress)
Using the obtained elastomer layer with a thickness of 1 mm, a dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K6251 (2004), and the obtained dumbbell-shaped No. 3 test piece was subjected to heat treatment at 25 ° C. , the tensile stress M ₁₀₀ at 100% elongation, and the tensile stress M ₃₀₀ at 300% elongation were measured. The unit is MPa. Three samples were used, and the average value of the three values was used as the measured value. Table 3 shows the evaluation results.

Using the obtained elastomer layer with a thickness of 1 mm, a dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K6251 (2004), and the obtained dumbbell-shaped No. 3 test piece was subjected to heat treatment at 25 ° C. , the breaking elongation was measured.
The elongation at break was calculated based on the formula: [movement distance between chucks (mm)]÷[initial distance between chucks (60 mm)]×100. The unit is %. Three samples were used, and the average value of the three values was used as the measured value. Table 3 shows the evaluation results.

In Table 3, "not measurable" in the coefficient of dynamic friction means that the slide piece did not move with respect to the surface of the sample (elastomer layer) in the above method of measuring the coefficient of dynamic friction, and the measurement could not be performed.

<Slipping test 1>
The resulting silicone rubber curable composition was cured at 170° C. for 15 minutes and 200° C. for 4 hours to form a cylindrical member having a diameter of 29 mm and a thickness of 12.5 mm. The outer surface of this columnar member was provided with surface irregularities having the surface Ra in Table 4 during molding. The surface roughness Ra (μm) of the cylindrical member was measured by the same method as the surface roughness Ra described above.
In Table 4, when molding the cylindrical member in Test 1, a mold with a smooth molding surface was used. used the mold.

In order to verify the applicability to gaskets, the obtained cylindrical member (rubber member) was inserted into a PP cylindrical tube with an inner diameter of 29 mm with a rod-shaped jig, and the outer surface of the cylindrical member was Sliding property was evaluated.
When the rubber member felt strong resistance during insertion and the rubber member did not slip, it was evaluated as x;

In Tests 3 to 5, in which the unevenness of the surface was Ra=4.0 μm or more, no resistance was felt during insertion, and good slip properties were exhibited. In addition, good slippage was obtained even during repeated insertion.
In Test 2, in which the unevenness of the surface was Ra=1.0 μm or more and less than 4.0, the rubber member could be inserted, but some resistance was felt.
On the other hand, in Test 1, in which the surface unevenness was less than Ra=1.0 μm, strong resistance was felt during insertion, and the rubber member could not be inserted.

<Slipping test 2>
On a flat test stand, the uneven surface of the elastomer layer obtained in each example/comparative example and the surface of the mating sheet material shown in Table 5 are slid in the horizontal direction while being in contact with each other to form a sheet. A mutual rubbing test was carried out and evaluated based on the following evaluation criteria. Table 5 shows the evaluation results.
When the elastomer layer felt strong resistance when rubbed against each other and the elastomer layer did not slip, it was evaluated as x.
As shown in Table 5, "the same type of sheet" was used as the resin mating sheet material, and "SUS304" (stainless steel) was used as the metal mating sheet material.
In the case of the "homogeneous sheet", for example, two elastomer layers of Example 1 were prepared, and the uneven surfaces of the two elastomer layers of Example 1 were brought into contact with each other to conduct the rubbing test. Other examples and comparative examples were also evaluated in the same manner.

It was found that the elastomer layers of Examples 1 to 11 maintained their rubber properties (physical properties) as compared with Comparative Example 1, and were excellent in slipperiness. In particular, the surface of the elastomer layer of Examples 6-11 was found to be further improved in slipperiness compared to Examples 1-5 from the results of the slipperiness test. It is expected that the molded articles having the elastomer layer of these examples will exhibit good slip properties while maintaining the desired rubber properties of the elastomer layer.

10 Upper mold 20 Lower mold 30, 40 Concavo-convex transfer film 32 Surface 50 Elastomer 52 Surface

Claims (9)

A molded article comprising an elastomer layer,
A molded article, wherein the elastomer layer has a surface roughness Ra of 1.05 μm or more on at least one side. A molded article according to claim 1,
A molded article, wherein the tack peak value TP on the surface of the elastomer layer is 4N or less, as measured by the following measurement procedure.
(Measurement procedure)
An aluminum probe having a flat surface with an area of 150 mm ² is measured under the conditions of probe moving speed: 2.3 mm / sec, probe crimping strength: 12 N, crimping time: 6 seconds. The flat surface of the aluminum probe is a measurement sample. The tack peak value on the surface of the elastomer layer was measured five times by a probe tack test when the surface of the elastomer layer was brought into contact and peeled off upward at a probe moving speed of 2.3 mm/sec. Let the average value of the measured values be the tack peak value TP. A molded article according to claim 1 or 2,
A molded product, wherein the surface of the elastomer layer has a dynamic friction coefficient of 2.0 or less as measured according to JIS K7125. A molded article according to any one of claims 1 to 3,
A molded article, wherein the elongation at break of the elastomer layer is 500% or more and 2000% or less, as measured according to JIS K6251 (2004). A molded article according to any one of claims 1 to 4,
A molded article, wherein the elastomer layer has a tear strength of 25 N/mm or more, as measured according to JIS K6252 (2001). A molded article according to any one of claims 1 to 5,
A molded article, wherein the elastomer layer has a tensile strength of 6.0 MPa or more and 15 MPa or less, as measured according to JIS K6251 (2004). A molded article according to any one of claims 1 to 6,
A molded article, wherein the elastomer layer has a durometer hardness A of 40.0 or less as defined in accordance with JIS K6253 (1997). A molded article according to any one of claims 1 to 7,
The elastomer layer comprises one or more selected from the group consisting of silicone rubber, fluororubber, nitrile rubber, acrylic rubber, styrene rubber, chloroprene rubber, ethylene propylene rubber, urethane rubber, isoprene rubber, and natural rubber. . A molded article according to any one of claims 1 to 8,
A molded product, wherein the surface of the elastomer layer is a non-coated surface on which a coating layer comprising a slipperiness imparting agent is not formed.

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