JPH02187466A - Releasable coating organopolysiloxane composition - Google Patents

Abstract

PURPOSE:To provide the title composition outstanding in curability, excellent in the releasability of the cured film therefrom in low-speed-high-speed tensilization, comprising a phenyl group-contg. organopolysiloxane of high vinyl value and a methyl group-contg. organopolysiloxane of lower vinyl value. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100 pts.wt. of a blend of A1: an organopolysiloxane of formula I [R<1> is hydroxyl, vinyl, etc.; R<2> is methyl, etc.; R<3> is methyl, phenyl, etc.; 0.9<=x/(x+y+z)<=0.975. 0.005<= y/(x+y+z) <=0.03, 0.03, <=Z/(x+y+z)<=0.07, (x+y+z) being polymerization degree corresponding to >=1000 cst in the viscos ity (25 deg.C)] and A2: a second organopolysiloxane of formula II [R<4> is hydroxyl, vinyl, etc.; R<5> is methyl, etc.; 0.97<=p/(p+q)<=1, 0<=q/(p+q)<=0.03] with (B) 5-100 pts.wt. of an organohydrogenpolysiloxane containing in one molecule three or more hydrogen atoms bound to silicon and (C) a catalytic amount of platinum (compound).

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an organopolysiloxane composition for releasable coatings, and in particular, it has excellent curability and the resulting cured film has a low to high releasability. The present invention relates to an organopolysiloxane composition for a releasable coating that is excellent in speed pulling.

[Prior art] In order to impart releasability to the surface of base materials such as films and sheets made from cellulose, synthetic resins, synthetic fibers, etc., a silicone composition that forms a cured film with releasability is applied. It is well known to do so. Practical examples include paper coated with organopolysiloxane, which is commonly used for adhesive tapes and adhesive labels, and is also often used as wrapping paper for sticky objects such as raw rubber, asphalt, and some foods. ing.

As a silicone composition for this purpose, a so-called addition reaction type silicone composition is known which is mainly composed of an organopolysiloxane containing a vinyl group and an organohydrodiene polysiloxane having a hydrogen atom bonded to a silicon atom. It is being When this addition reaction type silicone composition is applied to the surface of a base material and cured to form a film, the base material used is generally thin, less than 100 μm, and has no heat resistance. In consideration of the economic efficiency of the treatment, heat treatment is usually performed at 100 to 200° C. for a short time of about 5 to 60 seconds. Therefore, several silicone-based release compositions are known that can form a cured film under these processing conditions.

However, these strippable compositions have unresolved problems. That is, in recent years, pressure-sensitive adhesives or pressure-sensitive adhesives have been required to further improve their tackiness or adhesion, and organopolysiloxane compositions to be used in combination with these have also required Although it has been desired to provide a cured film with even better releasability, the present situation is that no cured film has been found that satisfies this releasability.

For example, regarding adhesive tape, especially double-sided tape,
During the manufacturing process of the tape or, in some cases, the use process, it is required to peel off the substrate coated with the cured organopolysiloxane film from the adhesive surface at a high speed of 20 to 200 m/min. The magnitude of peeling resistance during high-speed peeling is an extremely important practical property. In other words, if the peel resistance is high, the base material may tear if glassine paper is used as the base material, or the laminated polyethylene may float when polyethylene laminated paper is used as the base material. arise. In addition, in the process of removing adhesive label paper from the organopolysiloxane film-coated base material in the process of removing labels, it is now required to perform the process at increasingly high speeds. However, the size of the scum is also becoming smaller due to cost reductions, and the peel resistance is also an important practical characteristic here. In other words, if the peeling resistance is high, the scraps will easily break, leading to process troubles or reduced productivity. Therefore, it has excellent curing properties and low speed range (0
, 3 m/min or less) to high speed range (200 m/min or more). moreover,
When processing at high speeds, the cured film surface of organopolysiloxane may come into contact with various rolls at high speeds.
It is better for this film surface to have slipperiness. That is, the smaller the coefficient of friction between the cured organopolysiloxane film and the various rolls, the better.

In order to solve these problems, various organopolysiloxane compositions for releasable coatings have been proposed.

The mainstream is a composition based mainly on organopolysiloxane (vinyl raw rubber) containing vinyl groups with a high degree of polymerization, but using raw rubber with a relatively low vinyl value certainly provides excellent releasability at low speeds. However, in the high speed range, the peel resistance is large and unsatisfactory.If raw rubber with a relatively high vinyl value is used, the peel resistance is small in the high speed range, but the peel resistance becomes large in the low speed range, and If a mixture of raw rubber with a high vinyl value is used, the properties will be unsatisfactory, and the residual adhesion rate will be significantly reduced. In any case, there was nothing that satisfied peeling resistance throughout the low to high speed range. Other attempts to solve the problem of peel resistance include increasing the thickness of the organopolysiloxane cured coating.

However, this method requires a film thickness of 2 μm or more compared to the usual 1 μm thickness, which is economically disadvantageous.

In addition, it has been reported that with organopolysiloxane compositions for releasable coatings that are mainly based on raw vinyl rubber with a high degree of polymerization, it is essentially impossible to simultaneously reduce peel resistance in the low-speed to high-speed ranges. (See page 60 of the September 1985 issue of Packaging Technology).

[Problems to be Solved by the Invention] The present invention solves the problems of the organopolysiloxane composition described above, has good curability, reduces peel resistance of the cured film from low speed range to high speed range, and improves the hardness of the cured film. This invention was made in order to provide an organopolysiloxane composition for releasable coatings that has a small coefficient of friction and does not adversely affect the adhesive substances it comes into contact with.

[Means for Solving the Problems] As a result of intensive research by the present inventors to solve the above problems,
The main base is organopolysiloxane (vinyl raw rubber containing phenyl groups), which has a relatively high vinyl value, contains phenyl groups, is linear, and has a high degree of polymerization. raw rubber)
They discovered that it is possible to achieve the objective by using them in combination, and after further studies on the amount of phenyl groups and vinyl groups in raw rubber, they completed the present invention.

That is, the organopolysiloxane composition for releasable coating of the present invention has the following formula:
y+z is 25 of a 30% by weight solution dissolved in toluene.
It represents the value of the degree of polymerization at which the viscosity at °C is 1,000 centistocx or more. ] and the organopolysiloxane represented by the formula [wherein R1 represents the same or different groups selected from hydroxyl group, vinyl group and methyl group, R2 represents methyl group, ethyl group, propyl group and 3, 3.3-)-Represents the same or different groups selected from the group R3 is the same or different groups selected from the methyl group and the phenyl group (provided that R3's bonded to the same silicon atom) at least one of which is a phenyl group), and x, y, and z each satisfy 0.9≦X / (X +
y + z )≦0.975.0.005≦y/ (
x+y+z)≦0.03.0.03≦Z/(in the formula, R4
represents the same or different groups selected from hydroxyl group, vinyl group and methyl group, R5 is methyl group, ethyl group,
p represents the same or different groups selected from propyl and 3,3,3-trifluoropropyl;

q is 0.97≦p/(p+q)≦1.0.0≦, respectively.
q/ represents an integer satisfying (p+q)≦0.03, p+
q represents the degree of polymerization at which the viscosity of a 30% by weight solution in toluene at 25° C. is 1,000 centistics or more. ) Mixture of organopolysiloxanes represented by 1001i parts (2) 1
At least 3 hydrogen atoms bonded to silicon atoms in the molecule
organohydrodiene polysiloxane containing
It is characterized by comprising platinum or a platinum compound in a catalytic amount of 5 to 100 parts by weight (3).

The present invention will be explained in detail below.

The organopolysiloxane component a) that constitutes the first component has the same or different general formula (however, at least one of the aS bonded to the same silicon atom is a phenyl group)6
X* y, Z are each 0.9≦X/(x+y+z)
≦0.975.0.005≦y/ (x+y+z)≦0
．． 03.0.03≦z/(x+y+z)≦0.07, which is an integer expressed by the following. R1 in the formula is a group selected from a hydroxyl group, a vinyl group and a methyl group, preferably a vinyl group. R2 is the same or different group selected from methyl group, ethyl group, propyl group and 3,3,3-trifluoropropyl group, and preferably 90% or more of R2 is methyl group. R3 is selected from a methyl group or a phenyl group. Although the peel resistance of the film in the low-speed peel region can be achieved to some extent, there is a lot of migration from the cured film to the adhesive substance that comes into contact with it (migration).
This significantly reduces the residual adhesive strength and deteriorates the performance of the adhesive material. Moreover, if the amount exceeds 3 mol %, the compatibility with the components used in combination becomes poor, the curability decreases, and the resulting cured film has a high peel resistance in both the low speed and high speed ranges.

However, the preferable range is 1 to 2.5 mol %.The peel resistance of the cured film in the low speed range is small and satisfactory, but the peel resistance increases in the high speed range. Moreover, when the amount exceeds 7 mol %, the peel resistance of the cured film obtained in the high speed range is small and satisfactory, but the peel resistance in the low speed range becomes large. Therefore, it is preferably in the range of 91.5 to 95.0 mol%. ) (The value of +y+z must indicate the degree of polymerization such that the viscosity of a 30% by weight solution of this organopolysiloxane dissolved in toluene at 25°C is 1,000 centistics or more. Although there is some variation depending on the type of group bonded to the atom, the value is usually 2,000 or more.The preferred range of
0 centistokes, and such organopolysiloxane itself is gum-like and has a high degree of polymerization.

The other component that constitutes the first component is the general formula However, the preferred range is 4 to 6 mol%.

It is an organopolysiloxane defined within the range of 90 to 97.5 mol%. R4 in the formula
is a group selected from a hydroxyl group, a vinyl group and a methyl group, preferably a hydroxyl group. R5 is the same or different group selected from methyl group, ethyl group, propyl group and 3,3.3 trifluoropropyl group, preferably methyl group, more preferably 90% or more is methyl group. preferable.

p and q are each 0.97≦p/ (p+q)≦1.0
, is an integer such that O≦q/ (p+q)≦0.03, but if q is 0, which indicates 100 mol%, R
4 is preferably a hydroxyl group or a vinyl group; in the case of a methyl group, the resulting cured film has a lower residual adhesive strength,
The peeling resistance of the resulting cured film in the low speed range will be high, the coefficient of friction will increase, and the slip property will be lost, so it needs to be 3 mol% or less, but the preferable range is within the range of %. This is determined by the following. The value of p + q must indicate a degree of polymerization such that the viscosity of a 30% by weight solution of this organopolysiloxane in toluene at 25°C is 1,000 centistics or more. It is selected from among polysiloxanes depending on the purpose, but the viscosity is 30 above.
Preferably, the weight percent solution viscosity is from 3,000 to 15,000 centistokes.

The weight ratio of component (a) to component (a) is not particularly limited, but preferably component (a)/component (a) is 70/30 or more.
9515, which allows the characteristics of the composition of the present invention to be better expressed.

In addition, it is preferable that component (a) and component (a) be in an intermediate range between mutually compatible and incompatible components, thereby better achieving the objective of peeling resistance in both low-speed and high-speed regions. be able to.

Next, the organohydrodiene polysiloxane as the second component constituting the organopolysiloxane composition of the present invention may be a known organohydrodiene polysiloxane used in this type of addition reaction type organopolysiloxane composition, and this has one molecule. Any material having at least three hydrogen atoms bonded to silicon atoms therein may be used. It is preferable that 90 mol% or more of the organic groups bonded to silicon atoms other than hydrogen atoms be methyl groups. As this type of polysiloxane (CH3)
H5IO unit, H5iO+, s unit, (CHs)zs
iO unit, CHsSIO+, s unit, (Clls)
2H5iOo, s unit or (CHs) 5sfO
Examples include homopolymers or copolymers consisting of o and s units, which may be straight, branched, or cyclic, and have a viscosity at 25°C of 10 to 1,000 centistokes. Preferably.

The amount of organohydrodiene polysiloxane to be blended may be determined according to the amount of vinyl groups contained in the first component, but from the viewpoint of the formation of a cured film, the slipperiness of the film, and the peeling performance, the amount of 1001i of the first component 5~ioo for part
It is necessary to make it into parts by weight, preferably 7 to 70 parts by weight.
Parts by weight range.

Further, the third component in the composition of the present invention is the above-mentioned first component.
and a catalyst for causing an addition reaction of the second component,
Known catalysts for this type of reaction may be used, and examples thereof include chloroplatinic acid, alcoholic solutions of chloroplatinic acid, aldehyde solutions, and complex salts of chloroplatinic acid and various olefins and vinyl siloxanes. Platinum black or platinum supported on various carriers may also be used. Note that the amount of the third component to be added may be a catalytic amount, and in order to obtain a good cured film, and from an economic standpoint, the amount of platinum is in the range of 1 to 1,000 ppm based on 100 parts by weight of the first component. And it is sufficient.

The composition of the present invention can be obtained by blending predetermined amounts of the first to third components described above, but it is preferable to uniformly mix the first component and the second component in advance and then add the third component. In addition, for the purpose of suppressing the activity of the platinum catalyst, which is the third component, activity inhibitors such as various organic nitrogen compounds, organic phosphorus compounds, acetylene compounds, oxime compounds, and organic chloro compounds may be added as necessary. .

The composition of the present invention exhibits sufficient adhesion to substrates without the addition of adhesion improvers or reinforcing fillers, and the cured film obtained from it has excellent abrasion resistance. However, if necessary, γ-glycidoxyprobyltrimethoxysilane may be used as an adhesion improving agent to the base material.
γ-methacryloxypropyltrimethoxysilane or a (co)hydrolyzate thereof may be added, and dry process silica such as humid silica, wet process silica, titanium oxide, cerium oxide, carbon black, mica, etc. Inorganic fillers, binders, etc. may be added.

In order to uniformly apply the composition of the present invention to a substrate, it can be diluted with a solvent as necessary.

This solvent may be any solvent as long as it dissolves the composition of the present invention and is inert to each component, such as toluene,
Hydrocarbons such as xylene, benzene, hexane, heptane and chlorinated hydrocarbons are used.

Note that the base material treated with the composition of the present invention has a
Heat at a temperature of 200°C for 2 to 30 seconds, or use an ultraviolet irradiator to emit 0.2
A cured film may be formed on the surface by irradiating for more than a second.

[Effects of the Invention] The composition of the present invention forms a cured film that has sufficient bonding properties and does not come off under relatively low temperature and short curing conditions, and the cured film has a peeling rate ranging from low to high peeling speeds. It has significantly reduced peeling resistance compared to conventional products, has a low friction coefficient, and has almost no migration substances from the cured film, so it has the characteristics of not having a negative effect on adhesive substances in contact with the film. This is extremely advantageous industrially.

[Example] Next, examples of the present invention will be given. Parts in the examples are parts by weight,
Further, the viscosity is a value measured at 25°C.

Example 1 A 30% by weight solution dissolved in toluene has a viscosity of 5,
000 centistokes, both ends of the molecular chain are blocked with dimethylvinylsilyl groups, and the copolymer contains 5 mol% of methylvinylsiloxane units, 1 mol% of diphenylsiloxane units, and 94 mol% of dimethylsiloxane units ( 1) 90 parts and 30% by weight dissolved in toluene
10 parts of dimethylsiloxane (II) whose viscosity is 7,500 centistokes and whose molecular chain ends are capped with dimethylvinylsilyl groups is dissolved in 2,000 parts of toluene. 8 parts of methylhydrodienepolysiloxane with a viscosity of 25 centistokes and 4 parts of 3-methyl-1-butyn-3-ol are added and mixed uniformly, and then a complex salt of platinum and vinylsiloxane is added. 3 parts (above copolymer (I)
A composition was prepared by adding 10,100 pp of platinum to the total amount of dimethylsiloxane (II).

Next, the curability of the obtained composition, the slipperiness of the cured film, the residual adhesion rate, and the peel resistance were measured by the following methods. The measurement results are shown in Table 1. In addition, the following measuring method was similarly applied to Examples 2 to 3 and Comparative Examples 1 to 5 described later.

Preparation of Sample After 10 minutes had elapsed since the addition of the catalyst, the composition was weighed 80 g/glassine paper (manufactured by Tagawa Paper Co., Ltd.) with a solid content of approximately 1.0 g/l.
r? A cured film was formed by applying heat treatment in a hot air circulation drying oven at 180° C. for 5 seconds to prepare a sample for curing property measurement.

In addition, samples for measuring peel resistance, slipperiness, and residual adhesion rate were prepared by applying the composition to the above glassine paper at a solid content of approximately 1.0 g/r.
The film was coated so as to have an angle of n', and was cured by heat treatment at 180° C. for 8 seconds in the above-mentioned drying oven.

Curability Measurement The surface of the cured film of the sample was rubbed with a finger, and the degree of cloudiness and shedding was observed and evaluated based on the following criteria.

A: No clouding or falling off at all.

B: Slight clouding or shedding occurs.

C: Clouding and falling off occur.

Styrene-butadiene rubber weighing 200 g was placed on the surface of the cured film of the slippery sample, and this rubber was pulled parallel to the sample surface at 300 m1/min. Measure the force required to pull
The force required for pulling/200g was calculated as the coefficient of dynamic friction.

Residual adhesion rate Polyester Cheeve Lumirror 31B (manufactured by Nitto Electric Industry ■, trade name) was attached to the surface of the cured film of the sample, and 2
After aging at 70°C for 20 hours with a load of 0g/cm'' applied, the tape was peeled off and pasted on a stainless steel plate.Then, the tape was peeled off at an angle of 1809 to the surface of the stainless steel plate at a peeling rate of 3001111/ The force (g) required for peeling was measured.

On the other hand, an untreated tape that was not subjected to aging treatment was attached to a stainless steel plate, and the force (g) required to peel it off was measured. The force required to peel off the untreated tape is 100
The force required to peel off the aged tape was expressed as a percentage, and was defined as the residual adhesion rate.

Acrylic resin adhesive tape (manufactured by Nitto Electric Industry Co., Ltd.) and SBR adhesive tape (manufactured by Tanemizu Chemical Industry Co., Ltd.) were attached to the surface of the cured film of the peel resistance sample, at a temperature of 70°C and a pressure of 20 g/c.
After pressure bonding at m2 for 20 hours, peeling speed 0.3a/min, 60m
The sample was pulled at an angle of 180° using a high-speed tensile tester at a speed of 180 m/min or 180 m/min, and the force (g) required for peeling was measured.

Comparative Example 1 A composition was prepared in the same manner as in Example 1 except that dimethylsiloxane (II) used in Example 1 was not used. The curability and other properties of the resulting composition were as shown in Table 1.

Comparative Example 2 Dimethylsiloxane used in Example 1 (instead of *, both ends of the molecular chain are blocked with dimethylvinylsilyl groups, methylvinylsiloxane units are 4 mol%, dimethylsiloxane units are 96 mol%) A composition was prepared in the same manner as in Example 1, except that 10 parts of the copolymer (viscosity of a 30% by weight solution in toluene was 7,500 centistokes) was used.Curing of the resulting composition The characteristics and other characteristics were as shown in Table 1.

Comparative Example 3 Instead of the copolymer (I) used in Example 1, both ends of the molecular chain were blocked with dimethylvinylsilyl groups, and the methylvinylsiloxane units were 5 mol% and the dimethylsiloxane units were 95 mol%. Copolymer (viscosity of 30% by weight solution dissolved in toluene is 5.500 centistokes)
A composition was prepared in the same manner as in Example 1, except that 90 parts were used. The curability and other properties of the resulting composition were as shown in Table 1.

Example 2 The viscosity of a 30% solution in toluene at 25°C is 12.
000 centistokes, both ends of the molecular chain are blocked with dimethylvinylsilyl groups, 3.5 mol% of methylvinylsiloxane units, and 2% of diphenylsiloxane units.
80 parts of a copolymer (m) containing 94.5 mol% of dimethylsiloxane units and 3 dissolved in toluene.
The viscosity of the 0% by weight solution is 15.000 centistokes, both ends of the molecular chain are blocked with dimethylhydroxysilyl groups, and the methylvinylsiloxane unit is 0.2% by mole.
20 parts of a copolymer (rV) containing 99.8 mol% of dimethylsiloxane units was dissolved in 2,000 parts of toluene, and both ends of the molecular chain were blocked with trimethylsilyl groups.
Methylhydrodiene polysiloxane 6 with 75 mol% CH,H5IO units and a viscosity of 50 centistokes
and 3-methyl-1-butyne-3 used in Example 1.
- After adding 4 parts of ol and mixing uniformly, 10100 p of platinum was added to the total amount of 3 parts of the complex salt of platinum and vinyl siloxane (the above copolymer portion II) and (II/).
A composition was prepared by adding p. The curability and other properties of the resulting composition were as shown in Table 1.

Comparative Example 4 Instead of the copolymer (■■) used in Example 2, a 30% by weight solution dissolved in toluene had a viscosity of 12.000.
Centistokes, both ends of the molecular chain are blocked with dimethylhydroxysilyl groups, and the proportions are 3.5 mol% of methylvinylsiloxane units, 5 mol% of diphenylsiloxane units, and 91.5 mol% of dimethylsiloxane units. A composition was prepared in the same manner as in Example 2, except that 80 parts of the polymer was used. The curability and other properties of the resulting composition were as shown in Table 1.

Comparative Example 5 Instead of the copolymer (IV) used in Example 2, a 30% by weight solution dissolved in toluene had a viscosity of 15.000.
Centistokes, both ends of the molecule are blocked with trimethylsiloxy groups, and the dimethylsiloxane unit is 100.
A composition was prepared as in Example 2, except that 20 parts of mole % dimethylpolysiloxane was used. The curability and other properties of the resulting composition were as shown in Table 1.

As shown in Table 1, Example 1 was satisfactory in all characteristics. On the other hand, Comparative Examples 1 and 2 showed good residual adhesion rates, but the peeling resistance was high at any peeling speed from low to high, especially at low speeds.
The peel resistance at ft (0.3 m/min) was about three times that of Example 1. Comparative Example 3 showed good results in curing properties, slip properties, and peelability at low speed sub-11 (0.3 m/min), but the residual adhesion rate was poor, and The rate of increase in peel resistance was large, and the peel resistance was particularly large in high-speed peeling. Example 2 had satisfactory properties similar to Example 1, but Comparative Example 4 had inferior properties in all items, and Comparative Example 5 was inferior in residual adhesion rate and high-speed peeling resistance. .

Example 3 Polyethylene laminated paper (PE laminated paper), polyester film, and aluminum foil were used instead of the glassine paper used as the base material for sample preparation in Example 1, and treated in the same manner with the composition of Example 1. Then, the peel resistance of the cured film was measured. The results were as shown in Table 2.

Table 2 As shown in Table 2, even if the base material is replaced with PE-laminated paper, polyester film, or aluminum foil, the peeling resistance is the same at any peeling speed from low to high as in the case of glassine paper. was small and satisfying.

Claims (1)

[Claims] 1. (1) A) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ [In the formula, R^1 represents the same or different groups selected from hydroxyl group, vinyl group, and methyl group. where R^2 represents the same or different groups selected from methyl group, ethyl group, propyl group and 3,3,3-trifluoropropyl group, and R^3 is selected from methyl group and phenyl group. Represents the same or different groups (however, at least one of the R^3s bonded to the same silicon atom is a phenyl group), and x, y, and z are each 0.9≦x/
(x+y+z)≦0.975, 0.005≦y/(x+
y+z)≦0.03, 0.03≦z/(x+y+z)≦
represents an integer equal to 0.07, and x+y+z is the viscosity of a 30% by weight solution dissolved in toluene at 25°C of 1
,000 centistokes or more. ] Organopolysiloxane and b) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R^4 represents the same or different groups selected from hydroxyl group, vinyl group and methyl group, ^5 represents the same or different groups selected from methyl group, ethyl group, propyl group, and 3,3,3-trifluoropropyl group, and p and q are each 0.97≦p/(p+q)≦
1.0, represents an integer satisfying 0≦q/(p+q)≦0.03, where p+q is the value of the degree of polymerization such that the viscosity of a 30% by weight solution dissolved in toluene at 25°C is 1,000 centistokes or more represents. ) 100 parts by weight of a mixture of organopolysiloxanes represented by (2) 5 to 100 parts by weight of an organohydrodiene polysiloxane containing at least 3 hydrogen atoms bonded to silicon atoms in each molecule (3) A catalytic amount of platinum Or an organopolysiloxane composition for releasable coating, characterized by comprising a platinum compound.