JPH0211681A - Heat-resistant silicone pressure-sensitive adhesive sheet or tape - Google Patents

Abstract

PURPOSE:To improve the rewindability, etc., of a pressure-sensitive tape or sheet by stabilizing the releasability of its back for a long time by forming a pressure-sensitive silicon adhesive on the surface of an aromatic polyamide base and treating the back with a back treating agent comprising a low-MW polyolefin polyol and a polyurethane composition, a polyisocyanate compound, etc. CONSTITUTION:A silicon pressure-sensitive adhesive layer is formed on the surface of a sheet or tape-like aromatic polyamide base, and its back is treated with a back treating agent comprising a polyurethane composition essentially consisting of a low-MW polyolefin terminated with a hydroxyl group and having a number-average MW of 500-5000 and a polyisocyanate compound to obtain a heat-resistant pressure-sensitive silicone adhesive sheet or tape. Said back treating agent preferably contains at least one member selected from among the release agents based on a long-chain alkyl acrylate, a long-chain alkyl vinyl ester, a long-chain alkyl vinyl ether, a long-chain alkyl acrylamide and a polyamide.

Description

Detailed Description of the Invention (a) Field of application of pr or 1- The present invention uses a base material made of aromatic polyamide, forms a silicone adhesive on the surface of the aromatic polyamide base material, The present invention also relates to a heat-resistant silicone pressure-sensitive adhesive sheet/tape formed by applying a backside treatment agent to the back side of the aromatic polyamide base material.

(b) Conventional Technology Pressure-sensitive adhesive sheets and tapes are made by forming an adhesive on one side of a base material and winding this into a roll. When this product is used, it is rewound, but since the adhesive is strongly adhered to the back of the base material, when unwinding, if the adhesive strength is high, the pressure-sensitive adhesive sheet/tape will stretch and break. Tari, 8
It becomes difficult to recover. For this reason, in order to make it easier to unwind the pressure-sensitive adhesive sheet/tape,
It has been practiced to treat the back side of the tape with a release agent. Conventional stripping agents include long-chain alkyl acrylate stripping agents, alkyl vinyl ester stripping agents, and long-chain alkyl vinyl ether stripping agents. 8. Examples include long-chain alkyl acrylamide-based release agents and polyamide-based release agents.

However, in the case of silicone-based adhesive sheets and tapes coated with silicone-based adhesives, the adhesive strength of the silicone-based adhesive is extremely high, and the viscosity (aIJ) tends to become more rigid over time. Therefore, even if the back side of this type of silicone adhesive sheet/tape is treated with the above-mentioned release agent, the effect is poor. After manufacture and before use, the silicone adhesive firmly adheres to the base material of the sheet/tape, making it extremely difficult to unwind it.

For this reason, it is possible to use woven fabric or non-woven fabric as the base material, and to make it easier to unwind by reducing the adhesive area of the silicone adhesive due to the unevenness of the surface, or to use embossed plastic film or paper. A release sheet made of woven or nonwoven fabric is provided on the back surface of the base material, thereby preventing direct contact between the base material and the silicone adhesive.

In other words, the ff of this kind of silicone adhesive sheet/tape
1ll? Unfortunately, no practical treatment agent has yet been developed.

Incidentally, silicone pressure-sensitive adhesives are recognized to have excellent properties, such as high adhesive strength, as well as excellent heat resistance, chemical resistance, water resistance, aging resistance, and the like.

For this reason, in order to take advantage of the heat resistance of silicone adhesives and also improve the unwinding properties of silicone adhesive sheets and tapes, silicone adhesive sheets and tapes of this type are made using silicone adhesives as the base material. It has been proposed to use a material that has extremely poor affinity for and has excellent heat resistance. This material uses polyimide film, polytetrafluoroethylene film, etc. as the base material.

(c) Problem to be solved by the invention However, this product has extremely poor affinity with silicone adhesives, and for this reason, the side of the base material on which the silicone adhesive is laminated must be formed into a rough surface by a physical method. This improves the anchoring effect with silicone adhesives, thereby
It improves the adhesion between the silicone adhesive and the base material, and corona treatment, plasma treatment, matte treatment, etc. are used as physical methods for this purpose. However, the physical treatment equipment used in this method is extremely expensive, and productivity is limited because the surface of the base material is physically roughened and then used as a base material for silicone adhesive sheets and tapes. As a result, the production cost of silicone adhesive sheets and tapes increases significantly.

The present invention is a silicone adhesive sheet/tape using an aromatic polyamide as a base material for the silicone adhesive sheet/tape, and applying a back treatment agent to the back surface of the base material. By using a specific polyurethane composition or a mixture of a polyurethane composition and a known release agent as the agent, a heat-resistant silicone adhesive sheet with extremely excellent unwinding properties even when the back surface of the base material is smooth.・The purpose is to provide tapes.

(d) Means for Solving the Problems The inventors of the present invention have made extensive studies to resolve the above problems at once, and have found that this kind of heat-resistant silicone-based adhesive sheet/tape base material 1. It is preferable to use one made of aromatic polyamide and to use a polyurethane composition as the back treatment agent.Moreover, in the polyurethane composition, the polyol component has a hydroxyl group at the end of the molecule and has a number average molecular weight of 500. When using a low molecular weight polyolefin polyol of ~5000, 11
1? The inventors have discovered that it is possible to obtain a heat-resistant silicone-based pressure-sensitive adhesive sheet/tape with good rewindability even if the surface is smooth, and the present invention has been completed based on this discovery.

The present invention will be explained in detail below.

The present invention provides a silicone pressure-sensitive adhesive sheet/tape formed by forming a silicone pressure-sensitive adhesive on the surface of an aromatic polyamide base material. The surface is characterized by being a polyurethane composition having a hydroxyl group at the molecular end and containing as essential components a low molecular weight polyolefin polyol with an average molecular weight of 500 to 5000 and a polyisocyanate compound.

The aromatic polyamide base material used in the present invention includes:
As long as it is made of aromatic polyamide and is in the form of a sheet or tape, it is not particularly limited, regardless of the presence or absence of irregularities on the surface. formed,
It is preferable to use a material that can be used in a variety of applications and that can be easily manufactured.

The low molecular weight polyolefin polyol used in the present invention has one or more hydroxyl groups at the end of the molecule, has a substantially saturated main chain, has a molecular f of 1,500 to 5,000, and is liquid or semi-solid at room temperature. , among which the average number of hydroxyl groups per molecule is 1°5 or more, preferably 1.5
~8.0 is preferred.

If the molecular weight is less than 500, the cohesive force of the polyurethane composition will be low, and when the silicone adhesive sheet/tape wound into a roll is rewound and used, the polyurethane composition will cohesively fail and the silicone adhesive will fail. This is undesirable because it transfers to the adhesive side, and as a result, it reduces the adhesive strength of the silicone adhesive and has an adverse effect on the silicone adhesive. If the density exceeds 1t+, it becomes hard and brittle debris, which is not desirable.On the other hand, if it exceeds 5,000, the adhesion to the base material deteriorates, which is not desirable. A liquid one is preferable.

1- In the low molecular weight polyolefin polyol, at least one hydroxyl group is present only at the minute-r-terminus.
The use of a substantially saturated polyol with a main chain of
This is preferable for the reasons described below.

In other words, this low-molecular-weight polyolefin-based polyol does not contain a polar group in its skeleton, and therefore has essentially low hygroscopicity due to its structure, so it has better hydrolysis resistance than general ether-based and ester-based polyurethanes. - It has excellent moisture resistance, and since it does not contain unsaturated bonds in its molecules, it is stable and does not change in hardness, and has excellent heat resistance and weather resistance.

An example of producing the above-mentioned low-molecular polyolefin polyol is the method disclosed in Japanese Patent Publication No. 59-2452.

Further, the polyisocyanate compound used in the present invention is not particularly limited as long as it is a divalent incyanate compound, and specifically, for example, tetramethylene diisocyanate, hexamethylene diisocyanate, ethylene diisocyanate, etc. Isocyanate-1, phenylene-cyane), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 7-engineered di-ylmethane-4,4
diisocyanate, 1,5-7tale diisocyanate, isopropylbenzene-1,4-twincyanate, etc. In this case, trivalent isocyanate can also be used, but the blending ratio is It is necessary to adjust the amount to 15 parts by weight or less per 100 parts by weight of cyanate, and if the blending ratio exceeds 15 parts by weight, the physical properties as a back treatment agent may deteriorate, so it is preferably avoided.

The blending ratio of the above polyisocyanate (A) and low molecular weight polyolefin polyol (B) is (11
) 100 weight is usually 5 to 100-ir (A) per part
IFit part (7) can be selected in range, (A) is 5 fT
If it is less than j +itn, the cohesive force will be weak due to the low v4 density and transfer to the silicone adhesive will occur, which will have an adverse effect on the silicone adhesive, so it is not preferable. If the crosslinking density is exceeded, the crosslinking density will become too high, resulting in poor adhesion to the substrate.
This is undesirable because there is a risk of peeling between the 84 and 84 mm, and it is also disadvantageous in terms of cost.From these points of view, it is most desirable that (A> is about 1 part of lO to 80mff).

The polyurethane composition used in the present invention has component F as an essential component, but optionally stabilizers, dyes/pigments, flame retardants, modifiers, anti-aging agents, fillers, ultraviolet absorbers, Additives such as rust preventive agents and foaming agents may be added to 100 parts by weight of the low molecular weight polyolefin polyol in a proportion of 50 parts by weight or less.

The above fillers include cost reduction, cohesive force adjustment, coloring,
It is not particularly limited as long as it has tackiness, 1:4 g, etc., and specifically, for example, sand, natural silica such as quartz, zinc white, titanium oxide, wet method or dry method. Manufactured synthetic silica, kaolin, mica, aluminum hydroxide, calcium carbonate, barium sulfate, or natural silicates such as clay, talc, asbestos, calcium silicate,
Examples include synthetic silicates such as aluminum silicate, calcium sulfate, metal powders such as iron powder, magnesium carbonate, carbon blank, organic fibers, lath fibers, alumina, and starch.

The blending ratio of this filler is usually 10 to 41 M per 100 weight 41 M of the above-mentioned low molecular weight polyolefin polyol.
It can be selected within the range of 100 parts by weight, and the blending ratio is 100 parts by weight.
Heavy! If the amount is less than i part, the effect of the addition cannot be obtained, which is undesirable. On the other hand, if it exceeds 1()0 ton, the adhesive strength with the base material will be significantly reduced, which is undesirable. Therefore, from these points of view, Therefore, it is most desirable to set it to about 10-100 heavy sacrifice parts.

In the heat-resistant silicone pressure-sensitive adhesive sheet/tape of the present invention, the backside treatment agent further includes a long-chain alkyl acrylate release agent and a long-chain alkyl vinyl ester 1kla"1M
, a gc chain alkyl vinyl ether mold release agent, a long chain alkyl acrylamide mold release agent, or a polyamide mold release agent.

That is, this product uses each of the above-mentioned backside treatment agents as a main ingredient, and contains a known #11 type metal.

The long-chain alkyl acrylate mold release agent is a copolymer of an acrylic alkyl ester having 17 to 25 carbon atoms and acrylic acid, or a copolymer of a methacrylic acid furyl ester having 18 to 26 carbon atoms and acrylonitrile. Examples include copolymers of acrylic acid alkyl esters having 17 to 25 carbon atoms and methyl acrylate, copolymers of acrylic acid alkyl esters having 17 to 25 carbon atoms, acrylonitrile, methyl acrylate, and acrylic acid, etc. .

Further, as the long-chain alkyl vinyl ester thread release material, a copolymer of an acrylic acid alkyl ester having 16 to 24 carbon atoms and maleic anhydride may be used.

As the long chain alkyl vinyl ether mold release agent, K
Co-In combination of furkyl vinyl ether with M number 16-24 and maleic anhydride, co-111 combination of alkyl vinyl ether with M number 16-24 and acrylic acid, carbon 2rtL16
Examples include copolymers of alkyl vinyl ethers having 16 to 24 carbon atoms and acrylonitrile, copolymers of alkyl vinyl ethers having 16 to 24 carbon atoms, maleic anhydride, and methyl acrylate.

As the long chain alkyl acrylamide mold release agent,
Examples include a copolymer of an alkyl acrylamide with a carbon weight of 17 to 25 and acrylic acid, a copolymer of an alkyl acrylamide with a carbon number of 17 to 25 and acrylonitrile, and the like.

-1- The polyfumide-based mold release cutter is a homopolymer of N-i frequent fluoricyl acrylic acid amide or N-[[alkyl methacrylic acid amide) having an alkyl group having 8 or more carbon atoms, or a copolymer thereof. Copolymerization, or copolymers with other monomers that can be copolymerized with these acrylic acid amides (e.g., acrylic acid, methacrylic acid, acrylic ester, methacrylic ester, acrylonitrile, maleic anhydride, etc.) can be mentioned.

These known mold release agents may be used alone or in combination with 24t!
It is possible to mix more than
It is necessary to make the Ioltit part or less for 1 part, 10
Exceeding the weight part is not preferable because the compatibility may deteriorate and cause separation, the adhesive strength with the base material may deteriorate, and furthermore, the desired unwinding property may not be obtained.

In the case of the present invention, in the heat-resistant silicone pressure-sensitive adhesive sheet/tape, the back treatment agent J (thickness is preferably 10μ or more, and if it is less than 10μ, the thickness is thinner than 1
This is not preferable because the adhesive force of the silicone pressure-sensitive adhesive increases and the desired rewinding property may not be obtained. On the other hand, if the diameter exceeds 200μ, it is not only meaningless but also uneconomical, and from these points of view,
A range of ~100 μl is most desirable.

(e) Function The heat-resistant silicone pressure-sensitive adhesive sheet/tape of the present invention uses a material made of MW group polyamide as its base material, and the back treatment agent on the back surface thereof is formed of a specific polyurethane composition. Or, the polyurethane composition is used as a main ingredient, and the well-known Rinomachi? The base material made of 'It aromatic polyamide has extremely good heat resistance and can be used even under relatively high temperature conditions. It contains no unsaturated bonds and has good heat resistance and weather resistance, and the low molecular weight polyolefin polyol has no polarity and is extremely stable in terms of moisture resistance and heat resistance. For this reason,
Even if the silicone adhesive adheres, the peeling force due to warp 11 is stable, and the tape or sheet has an extremely good rewinding property over a long period of time.

Therefore, the heat-resistant silicone adhesive sheet/tape formed using this backing agent has extremely good unwinding properties over a long period of time, regardless of whether the surface of the base material is smooth or apricot. It has.

(f) Examples Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto. Polyol manufactured by Mitsubishi Kasei under the trade name Polytail R8
-5040 (r&average 9 children tfl 000-2000.
V average number of hydroxyl groups per molecule 2.4) 100 parts,
Diphenylmethane as a polyisonanate compound
4,4-noisocyanate (Mitsui Nitsuurethane Co., Ltd. 9I)
) was added thereto, and this was diluted with an organic solvent (for example, toluene) to prepare a back treatment agent having an ia degree of 30% by weight.

Next, the back surface treatment agent prepared above was applied to the back side of 50 μl of I''I-7 laminated paper, and heated and dried at a temperature of 150±10°C for 4 minutes to remove /i1F'1 of the back surface release agent. 2) Make it into a μ-shaped spear.

Then, benzoyl peroxide was added as a hardening agent to a silicone adhesive (manufactured by Toshi Silicone Co., Ltd., trade name S H-=4280') at a solid content weight ratio of 100:2, and toluene was further added. It was diluted to a concentration of 40%. This IE liquid was applied to the surface of the aramint paper, that is, the untreated surface, and heated and dried for 6 minutes at a temperature of 160 ± 10°C to obtain a silicone adhesive layer thickness of 40 μm, which was then rolled into a roll. Cut it to 19+aI1 width with a lathe,
A heat-resistant silicone adhesive tape of the present invention was obtained.

Using this roll-shaped heat-resistant silicone adhesive tape,
An unwinding test was conducted using the method shown below.

Tape at room temperature, temperature 35℃, relative humidity 80%, temperature 50℃
After being stored in each atmosphere at ℃ and 40% relative humidity for 7 days, it was taken out and its unwinding force was measured according to JIS Z1524 6.12.
Measured according to the regulations. The results are shown in Table 1.1゜From these results, it can be seen that all tapes have stable unwinding force even after being stored in each atmosphere for 7 days, and the unwinding properties are extremely good. .

Examples 2-1 to 2-5 The concentration of the back treatment agent adjusted in Example 1 was changed, and the thickness of the back treatment agent was 10 to 100 μm in the same manner as in Example 1.
・Each heat-resistant silicone adhesive tape of the present invention was obtained.

Table ttS1 shows the results of an unwinding test similar to that in Example 1 using each of these heat-resistant silicone adhesive tapes. From the results shown in Table 1, all tapes have stable unwinding force. However, it is recognized that the unwinding property is extremely good.

Comparative Example 1 A heat-resistant silicone adhesive tape was prepared in the same manner as in Example 1 except that a silicone mold release agent (manufactured by El Kagaku Kogyo Co., Ltd., trade name KS-774) was used as the back treatment agent. Obtained.

Using this heat-resistant silicone adhesive tape, the same 8-reverse test as in Example 1 was conducted, and the results are shown in Table 1.

The results shown in Table 1 show that when stored for 7 days in any atmosphere, the silicone adhesive and the back of the tape base material were strongly bonded, and when the tape was rewound, the 7-lamirad paper of the base material was destroyed between the layers. , it was recognized that rewinding was not possible.

Comparative Example 2 A heat-resistant silicone adhesive tape with no treated surface was used as a sample.

Using this heat-resistant silicone adhesive tape, the same unwinding test as in Example 1 was conducted, and the results are shown in Table 1.

From the results shown to the first person, 7II 1 in any atmosphere
In the case of 7fl I&, the silicone adhesive and the back of the tape base were strongly adhered, and when it was rewound, the 7 Lamirad paper of the base material was destroyed between the layers, making it impossible to unwind. Ta.

Comparative Example 3 In Example 1, a long chain alkyl vinyl ether mold release agent (manufactured by Roto Denki Kogyo Co., Ltd., trade name BP) was used as the back treatment agent.
A heat-resistant silicone pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that 110) was used.

Using this heat-resistant silicone adhesive tape, 81! Table 1 shows the results of the return test.

From the results shown in Table 1, the IP of the silicone adhesive and its tape base H when stored for 67 U in any atmosphere.
However, it adheres strongly, and when rewound, the base material 7 Lamirad paper becomes 1
It was recognized that it could be destroyed within +4 and cannot be rewound.

Examples 4-1 to 4-5 To 100 parts by weight of the solid content of the back treatment agent prepared in Example 1, a known long-chain alkyl vinyl ether back treatment (manufactured by Nitto Electric Industry Co., Ltd., Bp-i+, o) A back treatment agent used in the present invention was obtained by adding a triple layer.

Using this backside treatment agent, heat-resistant silicone adhesive tapes of the present invention were obtained in the same manner as in Example 2.

Using each of these heat-resistant silicone adhesive tapes, Example 1
Table 2 shows the results of an unwinding test similar to the above.

From the results shown in tpJ23, it is recognized that all of these tapes have stable unwinding force, and the unwinding properties are generally good.

Examples 5-1 to 5-5 3 parts by weight of a known long-chain alkyl acrylate mold release agent was added to 100 parts by weight of the solid content of the back treatment agent prepared in Example 1. 3 parts by weight of a vinyl ester mold release agent, 3 parts by weight of a long chain flukylacrylamide mold release agent, polyamide P, 3 m-flit part of a mold release agent added, long chain A mixture of 1.5 parts by weight of an alkyl acrylate mold release agent and 1.5 parts by weight of a long-chain alkyl vinyl ester mold release agent was used as the back treatment agent used in the present invention, as in Example 1. A heat-resistant silicone adhesive tape was obtained.

Using each of these heat-resistant silicone adhesive tapes, the same 8-back test as in Example 1 was conducted, and the results are shown in Section 3A.

From the results shown in Table 3, it was found that all of these tapes had stable unwinding force and had extremely good unwinding properties.

(The following is a blank space) From the results in 1- below, it can be seen that all of the products of each Example had good unwinding properties, and an extreme increase in peeling force of 4 #i was observed even after oral use against silicone adhesive sheets. It is confirmed that a stable peeling effect can be obtained without any problems.

On the other hand, in each of the comparative examples, the silicone adhesive and the back side of the tape base material were firmly adhered, and when unwinding, the 7-laminated paper of the base material broke between the layers, making unwinding impossible ( It was Noh.

(B) Effects of the invention The heat-resistant silicone adhesive sheet/tape of the present invention has the following advantages:
] Since it is configured as described above, the following effects are achieved.

In the heat-resistant silicone pressure-sensitive adhesive sheet/tape of item 1 of ill'I, a base material made of aromatic polyamide is used, and a back treatment agent made of a specific polyurethane composition is formed on the back side of the base material. This aromatic polyamide base material has extremely good heat resistance and can be used under high temperature conditions, and the above polyurethane composition uses a specific low molecular weight polyolefin polyol as its polyol component. This polyurethane molecule does not have unsaturated bonds and is stable over a long period of time. Therefore, even if the silicone adhesive adheres to the base material (sheet or tape), the peeling force due to l] is stable. As a result, the unwinding property of this heat-resistant silicone adhesive sheet/tape is
Even if the back surface of the base material is smooth, that is, there is no unevenness on the surface, and even if a base material that has poor affinity with silicone adhesives is not used, it is extremely stable over a long period of time. It has an effect.

In the heat-resistant silicone pressure-sensitive adhesive sheet/tape of Item 2, the base material is made of aromatic polyamide, and the back surface is coated with a back treatment agent using a specific polyurethane composition, or It is made by adding a known mold release agent to a processing agent, and this aromatic polyamide base material has extremely good heat resistance and can be used under high temperature conditions. The product uses a specific low-molecular-weight polyolefin polyol as its polyol component, and has no unsaturated bonds in the polyurethane molecules of 1) and is stable for a long period of time. Therefore, silicone adhesives are It adheres to the substrate (sheet or tape), but the peeling force by oral administration is stable, and as a result, the unwinding property of this heat-resistant silicone adhesive 4 sheet/tape is stable even if the back surface of the substrate is smooth. Even without surface irregularities and without using a base material that has poor affinity with silicone adhesives, it has the effect of providing extremely good HL over a long period of time.

Claims (2)

[Claims] (1) A silicone adhesive sheet/tape formed by forming a silicone adhesive on the surface of an aromatic polyamide base material, the back side of the silicone adhesive sheet/tape being
Has a hydroxyl group at the end of the molecule and has a number average molecular weight of 500 to 50
1. A heat-resistant silicone pressure-sensitive adhesive sheet/tape characterized in that it is treated with a backing agent consisting of a polyurethane composition containing a low molecular weight polyolefin polyol of 0.00 and a polyisocyanate compound as essential components. (2) In the heat-resistant silicone pressure-sensitive adhesive sheet/tape of claim 1, the backing agent includes a long-chain alkyl acrylate-based mold release agent, a long-chain alkyl vinyl ester-based mold release agent, and a long-chain alkyl vinyl ether-based mold release agent. A heat-resistant silicone pressure-sensitive adhesive sheet/tape containing at least one selected from a long-chain alkyl acrylamide mold release agent and a polyamide mold release agent.