JPS63130690A - Release agent - Google Patents

Abstract

PURPOSE:To provide a release agent which forms a coating film having a desirable balance among friction, release against an adherent and adhesion properties and which comprises an acrylic polymer, two particular types of polysiloxanes, a polyfunctional isocyanate compd. and a reaction catalyst. CONSTITUTION:An acrylic polymer (A) having a viscosity of 500-500,000 cP at 25 deg.C and containing at least two hydroxyl groups in its molecule is prepd. by copolymerizing an unsatd. monomer of the formula (wherein R1 is H or CH3; and R2 is a 1-18 C alkyl) with an unsatd. monomer having a hydroxyl group in the presence of a polymn. regulator. 100pts.wt. component (A) is mixed with 0.1-50pts.wt. straight-chainpolydiorganosiloxane (B) having a degree of polymerization of 2-2,000 and contg. a methyl group in an amt. of 0-80mol%, an org. group selected from among 2-20 C alkyl, cycloalkyl, aryl and aralkyl groups bonded to Si and at least two hydroxyl groups per molecule, 0-25pts.wt. polydimethylsiloxane (C) having a degree of polymerization of 10-20,000 and contg. at least two hydroxyl groups in this molecule, an isocyanate compd. (D) having an NCO group in an amt. of 0.2-5 equivalents relative to the hydroxyl groups of components (A) to (C), and a reaction catalyst (E).

Description

[Detailed Description of the Invention] Industrial Application Field The present invention consists of a silicone release agent blended with an acrylic polymer, which has a good balance between frictional properties (non-slip properties), releasability and adhesion to adherends. This invention relates to a release agent that can form an excellent film.

Conventional techniques and problems Silicone release agents have been known as release agents for imparting release properties to the surface of substrates made of paper such as laminated paper or plastic films, such as the back surface of adhesive tapes. .

However, with conventional silicone release agents, the film formed has too much releasability, resulting in a poor balance between releasability and adhesion to adherends such as adhesive surfaces; for example, in the case of adhesive tapes, In addition to not being able to apply multiple layers of tape, there was a problem that the tape was slippery and could easily cause the items to collapse when stacked together, such as cardboard boxes. This slipperiness is also the same in the case of a film made of a long-chain alkyl release agent.

Means for Solving the Problems As a result of intensive research to overcome the above problems, the present inventors discovered that the objective could be achieved by blending an acrylic polymer, and the present invention has been developed. I came to do this.

That is, the present invention uses 100 parts by weight of an acrylic polymer having two or more hydroxyl groups in the molecule, and an organic group having two or more hydroxyl groups in the molecule and bonding to a silicon atom having a methyl group and a carbon atom. 0.1 to 50 parts by weight of a linear polydiorganosiloxane having 2 to 20 alkyl groups, cycloalkyl groups, aryl groups, or aralkyl groups, and in which the proportion of methyl groups among the organic groups is 0 to 80 mol% 0 to 25 parts by weight of polydimethylsiloxane having two or more hydroxyl groups in the molecule, and a polyfunctional isocyanate compound in an amount such that the proportion of isocyanate groups is 0.2 to 5 equivalents to the total amount of hydroxyl groups in the above-mentioned components. and a reaction catalyst.

The acrylic polymer provides frictional properties, that is, non-slip properties, and the polysiloxane component such as linear polydiorganosiloxane provides releasability. By bonding through the hydroxyl group and the isocyanate group to form a vine structure, a film having excellent strength or cohesive force can be formed. Therefore, when used as an adhesive tape, the adhesive surface can be made less likely to be contaminated by film components.

This point is advantageous in preventing a decrease in adhesive strength due to contamination.

Examples of Components of the Invention The release agent of the present invention contains an acrylic polymer having two or more hydroxyl groups in the molecule.

The number of hydroxyl groups in the molecule is not limited to 2
~20 pieces is preferable. If the number of hydroxyl groups is one or less, the film formed will have poor strength and may contaminate adherends such as the adhesive surface. On the other hand, if the number of hydroxyl groups is too large, the formed film may lack elasticity and become brittle or slippery. From this point of view, it is believed that the non-slip property achieved by blending the acrylic polymer is due to the appropriate elasticity of the film based on the acrylic polymer.

Typical examples of acrylic polymers that can be used include the general formula:
An acrylic unsaturated monomer represented by CH2=C(Rs) COOR2 (wherein, R1 is hydrogen or a methyl group, and R2 is an alkyl group having 1 to 18 carbon atoms) and an unsaturated monomer having a hydroxyl group. Examples include copolymers with polymers. The number average molecular weight of the copolymer is 1000 to 300 (IQO1 preferably 20
00 to 10000 is appropriate.

Specific examples of the acrylic unsaturated monomer include methyl group, ethyl group, n-butyl group, isobutyl group, 1-ethylpropyl group, 1-methylpentyl group, 2 -methylpentyl group, 3-
Acrylic esters and methacrylic esters having linear or branched groups such as methylpentyl group, 1-ethylbutyl group, 2-ethylbutyl group, octyl group, isooctyl group, decyl group, dodecyl group, octadecyl group, etc. I can do it.

Specific examples of unsaturated monomers having hydroxyl groups include acrylic esters, methacrylic esters, and polyethylene glycol acrylate having 2-hydroxyethyl groups, 2-hydroxypropyl groups, and the like.

The amount of the unsaturated monomer having a hydroxyl group to be used is appropriately determined depending on the desired number of hydroxyl groups to be introduced, but the position of the hydroxyl group in the acrylic polymer is arbitrary.

The release agent of the present invention has a viscosity of 50°C at 25°C.
By using an acrylic polymer of 0 to 500,000 cP, a release agent that can be applied without solvent can be obtained. Such a low molecular weight acrylic polymer having fluidity at room temperature can be prepared by copolymerization using a polymerization regulator made of a compound having a mercapto group or the like. In this case, if a polymerization regulator having a hydroxyl group such as mercaptoethanol is used, an acrylic polymer having a hydroxyl group at the end of the polymer chain can be obtained. Acrylic polymers having a hydroxyl group at the end of the polymer chain have the advantage of making the formed film tough.

The release agent of the present invention contains as a component a linear polydiorganosiloxane having two or more hydroxyl groups in the molecule.

Although the number of hydroxyl groups in the molecule is not limited, it is 2 to 2° for the same reason as in the case of the acrylic polymer described above.
Five pieces is appropriate. Note that the position of the hydroxyl group is arbitrary,
It may be at both ends of a molecular chain, or at a side chain.

The linear polydiorganosiloxane that can be used is a substantially linear polydiorganosiloxane in which an organic group consisting of a methyl group, an alkyl group having 2 to 20 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group is bonded to the silicon atom. It is. Examples of the alkyl group having 2 to 20 carbon atoms include ethyl group, n-
Propyl group, isopropyl group, n-butyl group, isobutyl group, octyl group, decyl group, dodecyl group, octadecyl group, etc.; cycloalkyl group includes cyclopentyl group, cyclohexyl group, cyclooctyl group, etc.; aryl group includes Typical examples include phenyl, tolyl, xylyl, and the like, and typical aralkyl groups include benzyl, phenylethyl, and phenylpropyl.

The type of organic group bonded to the silicon atom may be one type or two or more types, but the bonding ratio of the methyl group is suitably 0 to 80 mol%. If the bond ratio of methyl groups to the organic groups exceeds 80 mol%, the formed film will become slippery, which is undesirable.

The degree of polymerization of linear polydiorganosiloxane is 2 to 20.
00, preferably 5-500. If the degree of polymerization is less than 2, it may volatilize when heated during coating on an object to be treated such as a base material for adhesive tape, and if it exceeds 2000, the viscosity of the release agent obtained will be high (and the coating properties will be affected). It becomes inferior and is not desirable.

The blending amount of the linear polydiorganosiloxane is suitably 0.1 to 50 parts by weight, preferably 0.5' to 20 parts by weight, per 100 parts by weight of the acrylic polymer.

If the amount is less than 0.1 part by weight, the film formed will have poor removability, and if it exceeds 50 parts by weight, the film formed will easily contaminate the adhesive surface etc. to which it is attached. Undesirable.

The release agent of the present invention contains polydimethylsiloxane having two or more hydroxyl groups in the molecule, if necessary.

The polydimethylsiloxane used has a degree of polymerization of 10 to
20,000, preferably 20 to 5,000 is suitable. If the degree of polymerization is less than 10, it may volatilize during heating when coating the object to be treated, and if it exceeds 20,000, the resulting release agent will have a high viscosity (and poor coating properties), which is undesirable. .

The appropriate amount of polydimethylsiloxane is 25 parts by weight or less per 100 parts by weight of the acrylic polymer. If the amount exceeds 25 parts by weight, the film formed will become slippery, which is not preferable.

Note that there are no particular limitations on the number and position of hydroxyl groups in boridime and tilsiloxashi.

The appropriate number is 2 to 25, and the positions may be at both ends of the molecular chain, or on a side chain.

The stripping agent of the present invention contains a polyfunctional isocyanate compound as a component.

A polyfunctional isocyanate compound is used as a crosslinking agent. That is, it is for chemically bonding the polysiloxane component and the acrylic polymer through the hydroxyl groups in each of the above-mentioned acrylic polymer, linear polydiorganosiloxane, and optional polydimethylsiloxane. The bonding treatment can be performed, for example, by heat treatment in the presence of a catalyst. This bonding treatment prevents contamination or deterioration of adhesive properties due to migration of the polysiloxane component to the adhesive surface when the adhesive surface is attached, for example.

Known polyfunctional isocyanate compounds can be used. Therefore, typical examples thereof include tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, or their multimers or modified products, as well as various hydroxyl group-containing compounds or hydroxyl group-containing compounds. Examples include adducts and prepolymers made of reactants with polyols contained therein.

The blending amount of the polyfunctional isocyanate compound is a ratio of 0.2 to 5 equivalents of isocyanate groups based on the total amount of hydroxyl groups in the acrylic polymer and linear polydiorganosiloxane, and further in the polydimethylsiloxane used as necessary. The amount is appropriate. If the proportion of isocyanate groups is less than 0.2 equivalents, the degree of curing of the film formed will be insufficient, and if the proportion of isocyanate groups exceeds 5 equivalents, a large amount of unreacted substances will remain, which may cause contamination. There is.

The stripping agent of the present invention contains a catalyst that participates in the reaction between hydroxyl groups and isocyanate groups. The type of reaction catalyst is not particularly limited, and typical examples include those based on organic acid metal salts and those based on amines. As the organic acid metal salt catalyst, those containing metals such as tin, zinc, lead, and iron are preferably used. Specific examples thereof include dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dioctyltin dilaurate, tin octoate, zinc naphtonite, and iron octoate. Further, specific examples of the amine catalyst include triethylenediamine, tetramethylbutanediamine, triethylamine, and the like.

The amount of reaction catalyst to be added may be a customary catalytic amount.

Preferably, 0.00 parts per 100 parts by weight of acrylic polymer.
The blending amount is 1 to 20 parts by weight.

The release agent of the present invention can be prepared by mixing, dissolving or dispersing the above-mentioned components.

As for the preparation method, a method in which a polyfunctional isocyanate compound is added to a mixture of other components is preferred. That is, it is preferable to mix components other than the polyfunctional isocyanate compound in advance, and add the polyfunctional isocyanate compound to this mixture to obtain the desired product.

The release agent of the present invention can be used in conventional release agent applications such as release paper and adhesive tape.

The coating can also be carried out by a conventional method.

That is, the coating can be applied to a generally processed object such as paper, cloth, plastic laminated paper, cloth, or plastic film using a known device such as a roll coater, kiss coater, slot die coater, or squeeze coater. At that time, the release agent may be used as it is, or may be diluted with an organic solvent to an appropriate viscosity.

In this case, the diluent may be in the form of a solution or a dispersion. Commonly used organic solvents include benzene, toluene, xylene, heptane, hexane, trichloroethylene, ethyl acetate, and methyl ethyl ketone.

Coating weights may be customary (in particular, 0.05% based on solids content).
The amount is generally 5 to 20 g/-.

A cured film is then obtained by heat-treating the coating film. As for the heat treatment temperature, the object to be treated (object to be coated)
Although it is related to the heat resistance, a suitable temperature is usually 60 to 200°C, preferably 100 to 180°C.

Effects of the Invention According to the release agent of the present invention, it is possible to perform releasability treatment on adherends such as adhesive surfaces with excellent balance between releasability and adhesion and non-staining properties.

Furthermore, the resulting film is strong and has elasticity, so it has excellent frictional properties (non-slip properties) and is resistant to slipping.

Reference Example (Preparation of Acrylic Polymer) 100 parts of n-butyl acrylate (parts by weight, same below),
5.4 parts of 2-hydroxyethyl acrylate and 2.6 parts of 2-mercaptoethanol were mixed, and 30% by weight of the resulting mixture was placed in a 200 cc four-pro flask.
While stirring, the inside of the flask was replaced with nitrogen to warm the internal temperature to 70°C, and after being replaced with nitrogen for about 60 minutes, α, α゛-
0.1 part of azobisisobutyronitrile was added to initiate polymerization (exotherm occurred after about 12 minutes).

Next, after the heat generation due to the start of polymerization becomes somewhat mild,
A mixture of 0.2 parts of α,α゛-azobisisobutyronitrile added to the remaining 70% by weight of the above mixture was gradually added into the flask over 3 hours using a dropping funnel to continue the reaction. .

After that, the polymerization operation is completed when the reaction system no longer generates heat, and the resulting reaction product is poured into a mixture of methanol and water to precipitate the resulting polymer, which is separated and dried under reduced pressure. Dehydration treatment was performed.

The number average molecular weight of the obtained Nacryl Bolima was 5200, and the average number of hydroxyl groups per -molecule was 2.5. Note that the number average molecular weight is a polystyrene equivalent value determined by gel permeation chromatography, and the average number of hydroxyl groups is a value calculated from the titration results and the number average molecular weight.

Example 1 100 parts of the acrylic polymer obtained in Reference Example was added with an average degree of polymerization of 8.
0 and 5 parts of polydimethylsiloxane having hydroxyl groups based on silanol groups at both ends, and an average degree of polymerization of 8 expressed by the formula
After adding 5 parts of polydimethyl-diphenylsiloxane (linear polydiorganosiloxane, 40 mol% phenyl groups, 60 mol% methyl groups) having hydroxyl groups based on diphenylsilanol groups at both ends and stirring, dibutyltin 5 parts of dilaurate were added and the mixture was sufficiently stirred to form a homogeneous mixture.

Next, 20 parts of a 751% ethyl acetate solution of a trifunctional isocyanate compound consisting of an adduct with 3 moles of 2.4-)lylene diisocyanate added per mole of trimethylolpropane was added to the resulting mixture. Then, the mixture was sufficiently stirred to form a uniform mixture system to obtain a release agent.

Example 2 A release agent was obtained in accordance with Example 1, except that the amount of polydimethyl-diphenylsiloxane was 10 parts and no polydimethylsiloxane was blended.

Comparative Example 1 A release agent was obtained in accordance with Example 1, except that the amount of polydimethylsiloxane was 10 parts and polydimethyl-diphenylsiloxane was not blended.

Comparative Example 2 A release agent was obtained according to Comparative Example 1, except that tetraphenyltetramethylsiloxane represented by the above formula was used instead of polydimethylsiloxane.

The release agents obtained in the evaluation test examples and comparative examples were applied to the polyethylene laminate surface of 120-thick polyethylene laminate kraft paper using a squeeze coater at a solid coating amount of 5 g/
The coated film was coated so that it had the following properties, and the coating film was cured by heat treatment at 110°C for 5 minutes, and then heated at 50°C for 2 days to obtain a release paper. An evaluation test was conducted.

[Peeling Force 1] After pasting the adhesive side of a piece of adhesive tape with a width of 25 wm (Craft Tape No. 718 manufactured by Nitto Electric Industries Co., Ltd.) on the releasability-treated side of release paper by moving a rubber roller 2- back and forth once, 20℃ with a load applied so that the entire bonded surface is pressed uniformly with a pressure of 50g/c+j,
The adhesive tape was left in an atmosphere of 65% R, H for 24 hours, then the load was removed and left for 1 hour.The adhesive tape piece was then peeled off at 180 degrees beer and at a peeling speed of 300 m/s.
minutes), and the force required to peel it off was measured.

[Residual adhesion rate] The adhesive tape piece after the above peeling force measurement was placed on a surface-cleaned stainless steel plate (SUS
304) by moving a 2 kg rubber roller back and forth once through the adhesive surface and leaving it for 30 minutes, then peeled off the adhesive tape at 180 degrees beer and at a peeling speed of 300 wmm/min. The force required was measured. Then, from the measured value, the ratio (percentage) to the value measured in the same manner for the adhesive tape piece before the peeling force measurement was calculated, and this was defined as the residual adhesion rate.

[Coefficient of Dynamic Friction 1 (Non-slip) In an atmosphere of 20°C and 65% R, H, a 40M square piece of release paper was placed on a horizontal stand, and the release-treated surface was placed on the release-treated surface of the release paper. (the releasable treated surfaces are in contact with each other), and 1000 g was applied so that the load was uniform.
put a weight on it, and cut the end of the release paper strip with this weight on it by 1
It was pulled in the horizontal direction at a speed of 0,000 on/min, and the coefficient of dynamic friction was calculated from the measured value of the resistance force at that time based on the following formula.

Dynamic friction coefficient=resistance force (g)/1000 g The results are shown in the table. Note that the numerical value is the average value of the measured values for 4 samples.

As is clear from the table, the film made of the release agent of the present invention has an excellent balance between releasability and adhesion to the adhesive surface of an adherend, such as an adhesive tape, and has an excellent residual adhesion rate (non-staining property). It has a coefficient of kinetic friction of <(,
Effective in preventing slipping. Therefore, when the adhesive tape for packaging is used for packaging cardboard boxes, the cardboard boxes can be stacked safely.

Claims (1)

[Claims] 1. 100 parts by weight of an acrylic polymer having two or more hydroxyl groups in the molecule;
and the organic group bonded to the silicon atom is a methyl group and has 2 carbon atoms.
~20 alkyl groups, cycloalkyl groups, aryl groups, or aralkyl groups, and 0.1 to 50 parts by weight of a linear polydiorganosiloxane in which the proportion of methyl groups among the organic groups is 0 to 80 mol%; , 0 to 25 parts by weight of polydimethylsiloxane having two or more hydroxyl groups in the molecule, and 0.2 to 25 parts by weight based on the total amount of hydroxyl groups in the above components.
A stripping agent comprising a polyfunctional isocyanate compound in an amount corresponding to 5 equivalents of isocyanate groups and a reaction catalyst. 2. The acrylic polymer is an unsaturated monomer represented by the general formula CH_2=C(R_1)COOR_2 (wherein R_1 is hydrogen or a methyl group, and R_2 is an alkyl group having 1 to 18 carbon atoms); 25°C obtained by copolymerizing an unsaturated monomer having a hydroxyl group in the presence of a polymerization regulator.
The release agent according to claim 1, which has a viscosity of 500 to 500,000 cP. 3. The degree of polymerization of the linear polydiorganosiloxane is 2 to 2.
000, the release agent according to claim 1. 4. The organic groups bonded to the silicon atom of the linear polydiorganosiloxane are 0 to 50 mol% of methyl groups and 1 phenyl group.
The release agent according to claim 1, which has a content of 00 to 50 mol%. 5. The degree of polymerization of polydimethylsiloxane is 10 to 2000
0. The release agent according to claim 1, which has a molecular weight of 0.