JPH0534391B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a silicone adhesive, and more specifically, it does not require a primer for various supports, cures at a relatively low temperature,
The present invention relates to an adhesive that has excellent cutting properties for the obtained adhesive tape or sheet. [Prior art and problems to be solved by the invention] Highly polymerized dimethylpolysiloxane whose molecular chain ends are blocked with hydroxyl groups is placed on a film-like support.
Silicone adhesives obtained by condensing a copolymer consisting of SiO ₂ units and (CH ₃ ) ₃ SiO _0.5 units are known. Tapes and sheets made by applying these adhesives to a support have excellent adhesive strength and cohesive strength, as well as excellent heat resistance, low-temperature properties, electrical properties, water resistance, etc., which are the inherent characteristics of silicone. However, on the other hand, if the support is made of organic fluororesin, polyimide resin, polyamideimide resin, polyamide resin, polyester resin, polyetherimide resin, polyether ether ketone resin, etc. Since the adhesive force (anchoring force) between the body and the adhesive layer is poor, the adhesive layer tends to transfer to the adherend during use. For this reason, such adhesive tapes and sheets are manufactured by chemically treating the surface of the support with sodium amide, naphthalene solution, potassium dichromate solution, etc., or by mechanically etching the surface. However, the anchoring force is still not sufficient, so a silicone undercoat layer (primer layer) is formed on the surface of the treated or untreated support using the method described above. A method of overcoating with a silicone adhesive has been proposed (Japanese Patent Publication No. 11950/1980, 10615/1982, and 29831/1983). Although the anchoring force can be improved by these methods, these methods require a complicated process of undercoating before applying the adhesive layer. Furthermore, when cutting adhesive tapes and sheets into arbitrary shapes, there has traditionally been a problem in that the adhesive can become stringy from the cut surface or ooze out, staining the adhesive surface and causing work problems. Primers alone are not the solution. On the other hand, silicone adhesives have the advantage of being able to adhere to any adherend, even to substrates that are difficult to adhere to with non-silicone adhesives. It has also come to be applied to supports with low heat resistance such as polyethylene, acetate, and cellophane. However, silicone adhesives usually use benzoyl peroxide as a vulcanizing agent, and generally require curing at 150°C or higher in order to balance tack, adhesive strength, cohesive strength, anchoring strength, etc.
For this reason, silicone adhesive tapes and sheets made from the above-mentioned supports, which have low heat resistance, cannot be baked at high temperatures, resulting in reduced cohesive force and anchoring force.
It has disadvantages in that sufficient properties cannot be achieved, such as insufficient migration resistance to the back side of the adhesive layer and the adhesion surface and insufficient cutability. [Means for solving the problems and their effects] The present invention aims to provide a silicone pressure-sensitive adhesive that improves the above-mentioned conventional drawbacks. (R in the formula is a substituted or unsubstituted monovalent hydrocarbon group, and 0.01 to
40 to 80 parts by weight of a diorganopolysiloxane (10 mol% is an alkenyl group, 3 to 20 mol% is an aryl group, n is an integer from 100 to 10,000), SiO ₂ units and R' ₃ SiO _0.5 units (R′ is the number of carbon atoms
It represents the following monovalent hydrocarbon group. ) and 60 to 20 parts by weight of a copolymer having a molar ratio of 1:0.3 to 1:1.5 and having at least one hydroxyl group directly bonded to a silicon atom in each molecule. , (b) an organohydrodiene polysiloxane in an amount sufficient to provide 1 to 30 Si-H bonds per vinyl group in component (a), and (c) a catalytic amount of a platinum-based catalyst. The invention relates to a silicone adhesive. In addition to the inherent characteristics of silicone adhesives, such as adhesiveness, heat resistance, low-temperature properties, electrical properties, and water resistance, this adhesive has several other advantages when compared to conventional silicone adhesives. First, because it has excellent anchoring power, adhesive tapes can be made without using primers. Therefore, even when these adhesive tapes are stored in a tightly rolled state for a long time and then used, there is no migration of the adhesive layer to the back surface of the support. Furthermore, no migration to the adhesive surface is observed during use. In addition, due to its excellent cutting properties, when cutting adhesive tapes and sheets into arbitrary shapes, the adhesive layer does not stretch, bleed, or turn over from the cut surface.
It can be cut cleanly and has excellent workability without staining the adherend, adhesive tape, or sheet. Furthermore, since it can be cured at low temperatures, it can also be used for supports with poor heat resistance. The silicone adhesive of the present invention is composed of the above-mentioned components (A) to (C).
Part by weight, copolymer of SiO ₂ units and R′ ₃ SiO _0.5 units
It is obtained by mixing and heating 60 to 20 parts by weight to cause a partial condensation reaction. (1) In the formula, R represents a substituted or unsubstituted monovalent hydrocarbon group, and these substituted or unsubstituted monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, and propyl groups, and vinyl groups. , alkenyl groups such as allyl groups, aryl groups such as phenyl groups, and groups in which hydrogen atoms bonded to carbon atoms of these hydrocarbon groups are partially substituted with halogen atoms, cyano groups, etc. are exemplified. For the diorganopolysiloxane represented by formula (1), the value of n, which indicates the degree of polymerization, is required to be in the range of 100 to 10,000, preferably 1,000 to 8,000; This is because the treated layer as an adhesive formed by the organopolysiloxane composition comprising component () has a large cohesive force and excellent adhesive strength. In addition, component (a) undergoes an addition reaction in the presence of organohydrodiene polysiloxane, component (b), and platinum-based catalyst, component (c), to form a treated layer with excellent cohesive strength and adhesive strength. is required. For this purpose, 0.01 of the total organic groups bonded to the silicon atom of the diorganopolysiloxane represented by formula (1) must be
It is required that ~10 mol%, preferably 0.1 to 5 mol%, are alkenyl groups. If the amount of this alkenyl group is too small, the crosslinking density will be low, making it impossible to obtain an adhesive layer with excellent cohesive force.
On the other hand, if the amount is too large, the crosslinking density will increase and the treated layer will become hard and have poor adhesiveness. In addition, in order to achieve anchoring power and cutting properties, which are the main objectives of the present invention, it is preferable that 3 to 20 mol% of the total organic groups in formula (1) be aryl groups, and no aryl groups are present. If the anchoring ability to the support is poor or the adhesive layer is transferred to the back side and the adhesive surface, or the adhesive layer is peeled away from the support when cutting, or the adhesive layer has poor adhesive cutting properties and the cut surface is This may cause the adhesive layer to stretch further, which is undesirable for work.If there are too many aryl groups, the compatibility between components (a) and (b) will deteriorate, resulting in poor adhesive strength, adhesive strength, cohesive strength, and It becomes impossible to achieve a sufficient balance of characteristics of anchoring force. The most preferred range is 5
~15 mol%. Furthermore, the structure in the molecular chain is not limited to one type of diorganosiloxane unit, and it goes without saying that it may be a mixture of two or more types of diorganosiloxane units. Next, the SiO ₂ units and R′ ₃ SiO _0.5 that undergo a partial condensation reaction with the diorganopolysiloxane of formula (1) described above
Copolymers with R′ 3 SiO 0.5 units are well known to those skilled in the art and include, for example, water glass or orthoalkyl silicate or a partial hydrolyzate thereof constituting the SiO ₂ unit and R′ ₃ SiO _0.5 unit. Trimethylchlorosilane, trimethylmethoxysilane, triethylchlorosilane, dimethylpropylchlorosilane, dimethylpropylmethoxysilane, dimethylvinylchlorosilane, dimethylvinylmethoxysilane,
It can be obtained by cohydrolyzing and condensing a silane such as hexamethyldisiloxane or at least one siloxane in the presence of an acid.
Regarding this copolymer of SiO ₂ units and R' ₃ SiO _0.5 units, if there are too many SiO ₂ units, the compatibility with the diorganopolysiloxane of formula (1) will be poor, and it will be difficult to partially condense with it. On the other hand, if the SiO ₂ units are too small, it becomes difficult to obtain an adhesive layer with excellent cohesive force. In order to obtain a balance between adhesive force, cohesive force, anchoring force and good cutting ability, SiO ₂ units and R′ ₃ are required.
The molar ratio of SiO _0.5 units is 1:0.3 to 1:1.5, preferably 1:0.5 to 1:1.3. It is also essential that each molecule has a hydroxyl group directly connected to a silicon atom. In addition, when the diorganopolysiloxane of formula (1) and the above copolymer are subjected to a partial condensation reaction, if the amount of diorganopolysiloxane is too large,
It is not possible to obtain an adhesive layer with excellent tack and adhesive strength, and if the amount is too low, cohesive strength,
Since it is not possible to obtain an adhesive layer with excellent anchoring power and cutting properties, the amount of copolymer is 60 to 20 parts by weight relative to 40 to 80 parts by weight of diorganopolysiloxane, as described above. That is required. The organohydrodiene polysiloxane as component (b) is a component that undergoes a crosslinking reaction with the component (a), and examples thereof include the following. R ² is a monovalent hydrocarbon group, Me is a methyl group, a=
2-4, b=0-4, but a+b=3-8 R ² and Me have the same meanings as above, R ³ is a hydrogen atom or a monovalent hydrocarbon group, p = 0 to 3000, q = 0
~3000, provided that each molecule has two or more hydrogen atoms bonded to silicon atoms. R ² and R ³ have the same meaning as above, c=1 or 2, d=2 or 3, but c+d=4 [R ² SiO _1.5 ] unit and [(R ² )(H)SiO] unit and further case An organohydrodiene polysiloxane with a resin structure consisting of [R ² ₂ SiO] units. The platinum or platinum compound as component (c) may be one that has been known as a catalyst for the addition reaction between a vinyl group-containing organopolysiloxane and an organohydrodiene polysiloxane. Examples include modified chloroplatinic acid, a complex of chloroplatinic acid and olefin, solid platinum supported on a carrier such as platinum black, alumina, or silica. The organopolysiloxane composition comprising components (a) to (c) according to the present invention described above is used by directly coating the surface of a tape or seed-like support to form a silicone adhesive layer. When applying the above-mentioned organopolysiloxane composition, in order to make it easier to apply, it is diluted with a solvent, and in order to further strengthen the coating film, fine powder silica-based fillers and these fillers are used. Silicone-based leakage agents (surfactants) that are added in small amounts to facilitate mixing and integration with the above-mentioned essential components, as well as inorganic and organic pigments and dyes that are added for the purpose of coloring. ,
There is no problem as long as it does not impede the purpose and effects of this invention. Further, a known retarder for suppressing the reaction can also be used in combination. Tape or sheet supports used include those made from organic fluorine polymers such as polytetrafluoroethylene, polyimide, polyamide, polyamideimide, polyester, polyetheretherketone, polyetherimide, polyethylene, Glass cloth, cotton cloth, Japanese paper,
Examples include tapes and sheet-like materials such as metal foil. The silicone adhesive according to the present invention is prepared by applying a coating solution of an organopolysiloxane composition consisting of components (a) to (c) onto such tape and sheet-like supports without applying an undercoat. It is used by coating it to form an adhesive layer. The coating amount of the organopolysiloxane composition consisting of components (a) to (c) is approximately 0.01 to 0.1 in film thickness (dry).
The desired properties can be obtained by simply leaving it at room temperature for 2 hours or more. Industrially, if you want to obtain characteristics in a shorter time, it is possible to accelerate heating, and the temperature is 70 to 130℃.
Just heat it for 1 to 20 minutes. Therefore, it has the advantage that even supports with poor heat resistance can be processed without causing deterioration. Furthermore, tapes and sheets coated with conventional silicone adhesives tend to suffer from undesirable phenomena called "adhesive peeling" and "adhesive floating" due to the influence of atmospheric temperature and humidity during long-term storage. However, the adhesive tapes and sheets obtained by this invention have a high adhesion of the organopolysiloxane composition to the support. Because of its excellent properties, it has excellent features that do not cause any of the above-mentioned drawbacks. This product exhibits extremely good adhesion to various materials, and furthermore, when it peels off after being attached to various material surfaces for a long time,
It has excellent features such as no migration of the adhesive layer on the adhesive surface, high adhesive strength even at low temperatures, and excellent cutting properties. [Example] Next, the present invention will be specifically explained with reference to Examples.
In the examples, all parts are parts by weight,
Adhesive properties such as tack, adhesive strength, cohesive strength,
The methods and conditions for measuring transferability, cuttability and holding power are as follows. [Tack] A steel ball (JIS G 4805 SUJ2) is rolled from a run-up distance of 10cm on a slope with an inclination angle of 30°, and the maximum diameter (in inches) of the steel ball that stops within the adhesive layer of 10cm is shown. (inclined ball tack measurement method). The conditions during the measurement were a temperature of 25±2°C and a relative humidity of 65±5%. [Adhesive strength] SUS 27 CP stainless steel plate (thickness 1.0 mm, width 30
Gently stick the test piece with the adhesive layer side down in the center of the test piece (mm, length 160mm), and then apply a roller (2000±50g coated with a rubber layer about 6mm thick) onto the test piece.
(made of metal), crimped the test piece by making one reciprocation at a crimping speed of approximately 300 mm/min. After crimping the test piece, leave it in a constant temperature and humidity room at 25±2℃ and 65±5%RH for 30 minutes or more, then fold the loose part back to 180°.
It is expressed as the peeling force when peeling off continuously at a speed of 300 mm/min. [Cohesive force] A test piece was pasted on a stainless steel plate in an area of 20 mm in length and 10 mm in width, a load of 1 kg was applied, and the temperature was 25 ± 2°C and 65 ±
The displacement distance after being left in an atmosphere of 5% RH for 30 minutes is also shown. [Transferability of the adhesive layer to the back of the tape] Adhesive tape rolled onto a bobbin was heated at 50°C and 90°C.
25±2 after being left in an atmosphere of %RH for 7 days.
℃, 65 ± 5% RH for 30 minutes, and then rapidly rewound at a speed equivalent to 50 to 100 m/min, the adhesive layer may migrate to the back of the tape or the tape may become sticky. Whether or not floating occurred in the agent layer was visually determined. [Cutability] When a cut is made with a cutter to a length of approximately 2 mm from the edge only on the support portion of an adhesive tape or sheet, and the adhesive is pulled horizontally to break, the adhesive layer does not peel or stretch from the broken surface. It was determined visually whether or not it would work. [Holding force] A test piece was pasted on a stainless steel plate in an area of 20 mm in length and 10 mm in width, a load of 500 was applied, and the test piece was suspended in a constant temperature dryer at 100°C, and the time taken to fall was measured. Reference Example Coating liquid I~ was prepared as follows. Coating liquid I; methylpolysiloxane resin consisting of 0.7 moles of Me ₃ SiO _0.5 units and 1 mole of SiO ₂ units
40 parts, Me ₂ SiO units, (C ₆ H ₅ ) ₂ SiO units, and (CH ₂ =CH) (Me)SiO units, with a degree of polymerization of 8000, consisting of hydroxyl group-capped raw rubber diorganopolysiloxane ( 3 vinyl groups among all organic groups
mol%, phenyl group (3 mol%)) are mixed with toluene, and this is heated at a temperature of 100 to 120°C.
A 60% toluene solution of organopolysiloxane was obtained by a partial condensation reaction for a period of time. For this toluene solution 2% by weight of methylhydrodiene polysiloxane represented by the formula is added, and the amount of platinum is
Add chloroplatinic acid to 15ppm and apply coating solution I.
was prepared. Coating liquid: Methylpolysiloxane resin consisting of 1.3 moles of Me ₃ SiO _0.5 units and 1 mole of SiO ₂ units
Raw rubber-like diorganopolymer with a degree of polymerization of 2000, consisting of 50 parts, Me ₂ SiO units, (Me) (C ₆ H ₅ ) SiO units, and (CH ₂ = CH) (Me) SiO units, and whose terminals are blocked with hydroxyl groups. 50 parts of siloxane (0.1 mol% of vinyl groups, 10 mol% of phenyl groups in total organic groups) are mixed with toluene, and the mixture is subjected to a partial condensation reaction at 100 to 120°C for about 6 hours, so that 60% of organopolysiloxane contains toluene. A solution was obtained. For 100 parts of this toluene solution A coating solution was prepared by adding 4 parts of methylhydrodiene polysiloxane shown by , adding chloroplatinic acid so that the amount of platinum was 20 ppm, and further diluting with toluene so that the nonvolatile content was 30% by weight. . Coating liquid: Methylpolysiloxane resin consisting of 0.9 mol of Me ₃ SiO _0.5 units and 1 mol of SiO ₂ units
50 parts, Me ₂ SiO unit and (C ₆ H ₅ ) ₂ SiO unit and (CH ₂ =CH) (Me)
A raw rubber-like diorganopolysiloxane with a degree of polymerization of 5000 hydroxyl groups blocked at both ends consisting of SiO units (1 mol% of vinyl groups, 5 phenyl groups in the total organic groups)
(mol%) were mixed with toluene and subjected to a partial condensation reaction at about 100° C. for 16 hours to obtain a 60% toluene solution of organopolysiloxane.
For 100 parts of this toluene solution, _0.5 unit of (Me) ₂ (H)SiO and (Me)(H)SiO
It consists of _1.5 units of C ₆ H ₅ SiO and 1.5 units of Me ₂ SiO, the average degree of polymerization is 40, the content of hydrogen atoms directly connected to silicon atoms is 25 mol%, and the phenyl group is 2 mol of all organic groups. % of organohydrodiene polysiloxane, to which the amount of platinum is
A coating solution was prepared by adding chloroplatinic acid to a concentration of 30 ppm. Coating liquid: A coating liquid was prepared by adding 1.2 parts of benzoyl peroxide and 50 parts of toluene to 100 parts of silicone adhesive KR-101-10 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.). Coating liquid: Methyl polysiloxane resin consisting of 0.7 moles of Me ₃ SiO _0.5 units and 1 mole of SiO ₂ units
40 parts, Me ₂ SiO unit and (C ₆ H ₅ ) ₂ SiO unit and (CH ₂ = CH) (Me)
Rubber-like organopolysiloxane with a degree of polymerization of 8000, consisting of SiO units and capped with hydroxyl groups (3 mol% of vinyl groups, 1.5 mol% of phenyl groups in the total organic groups)
(mol%) was mixed with toluene and subjected to a partial condensation reaction at a temperature of 100°C to 120°C for 4 hours to obtain a 60% toluene solution of organopolysiloxane. For this toluene solution 2% by weight of methylhydrodiene polysiloxane represented by the formula is added, and the amount of platinum is
A coating solution was prepared by adding chloroplatinic acid to a concentration of 15 ppm. Coating liquid: A coating liquid was prepared with the same formulation as the coating liquid except that only the platinum-based catalyst was removed. Example 1 The coating solution prepared in Reference Example was directly applied to a support consisting of a polytetrafluoroethylene tape, polyester tape, polyimide tape, and washi tape treated with sodium amide on one side of polytetrafluoroethylene having a thickness of 0.08 mm. The mixture was heated for a minute to form an adhesive layer with a thickness of 0.04 mm, thereby producing an adhesive tape. Table 1 shows the properties of these tapes. In addition, the comparative examples in Table 1 are 120% using coating liquid.
It was heated at ℃ for 5 minutes to form an adhesive layer with a thickness of 0.04 mm, thereby producing an adhesive tape. From Table 1, the effects of the present invention are clear,
The adhesive tape obtained without treatment with an undercoat had good cutting properties, there was no migration of the adhesive layer to the back side of the tape or to the adhesive surface, and it had extremely excellent workability and performance. Example 2 Table 2 shows the properties of an adhesive tape obtained by directly coating the coating solution prepared in Reference Example on a tape-shaped support made of the material shown in Table 2 and drying and curing it at 130° C. for 3 minutes. In addition, in Comparative Example 2 shown in Table 2, an adhesive tape was prepared by heating at 180° C. for 2 minutes using a coating liquid. In both cases, the thickness of the adhesive layer was adjusted to 0.04 mm. Example 3 Table 3 shows the various performances of the adhesive tape obtained by applying the coating solution shown in the reference example directly to a tape-shaped support made of the material shown in Table 3 and curing it by heating at 100°C for 5 minutes. show. In addition, in Comparative Example 3 in Table 3, an adhesive tape was produced using the coating liquid under the same conditions. The thickness of the adhesive layer was adjusted to 0.04 mm. As can be seen from Tables 2 and 3, the adhesive tape made using the adhesive according to the present invention has excellent adhesive properties at low and high temperatures, and has extremely good cutting properties, as well as the ability to transfer the adhesive layer to the back of the tape. There was no migration to the adhesive surface, and both workability and performance were excellent.

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Claims (1)

[Claims] 1 (a) General formula (In the formula, R is a substituted or unsubstituted monovalent hydrocarbon group, and 0.01 of the total organic groups represented by R
~10 mol% is an alkenyl group, 3~20 mol% is an aryl group, and n represents an integer from 100 to 10,000. ) diorganopolysiloxane 40
~80 parts by weight, and the molar ratio of SiO ₂ units and R' ₃ SiO _0.5 units (R' represents a monovalent hydrocarbon group having 3 or less carbon atoms) is 1:0.3 ~
A copolymer with a ratio of 1:1.5 and at least one hydroxyl group directly bonded to a silicon atom in each molecule60
(b) an organohydrodiene polysiloxane in an amount sufficient to provide 1 to 30 SiH bonds per vinyl group in component (a); and (c) a silicone adhesive comprising a catalytic amount of a platinum-based catalyst.