JP2000080135A - Production of graft copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an unreacted silicone macromonomer to be decreased by charging the total amt. of a silicone macromonomer into a polymerizer at the early stage and slowly supplying the total amt. or part of another free- radically polymerizable monomer into the polymerizer after the beginning of the polymn. SOLUTION: The silicone macromonomer is one having a free-radically polymerizable group [e.g. a (meth)acryloyl or styryl group] bonded to one terminal of a linear silicone molecule and pref. has a number average mol.wt. (by gel. permeation chromatography, in terms of polystyrene) of 1,000-100,000. Pref., the other free-radically polymerizable monomer consists mainly of a (meth)acrylic monomer and/or styrene; more specifically, 50-100 wt.% of it is pref. a (meth)acrylic monomer and/or styrene. Pref., the amt. of the silcone macromonomer is 0.5-60 wt.% of the total amt. of the monomers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a graft copolymer having silicone as a branch polymer.
The present invention relates to a production method capable of efficiently introducing silicone, and more specifically, to a graft copolymer having a characteristic that unreacted macromonomer can be reduced when a relatively large amount of silicone-based macromonomer is copolymerized. The present invention relates to a method for producing a polymer.

[0002]

2. Description of the Related Art Conventionally, in a method of producing a graft copolymer containing silicone, a method of copolymerizing a silicone-based macromonomer with another radically polymerizable monomer such as (meth) acrylic acid ester or styrene has been known. And a method for producing a graft copolymer having high purity. A method for producing a graft copolymer using a silicone-based macromonomer is disclosed in JP-B-46-9355.
And Japanese Patent Publication No. 1-39445.

However, the graft copolymer conventionally produced by the above method contains a small amount of unreacted silicone-based macromonomer,
When it was used as a coating agent, bleed-out from the coating-coated surface to another uncoated surface was likely to occur. For example, in a thermal transfer recording film in which the graft copolymer is applied for the purpose of providing a heat-resistant layer on the back surface of the film, the surface of the film, that is, the surface on which the ink is applied, is contaminated with the silicone-based macromonomer due to the bleed-out. As a result, blurring or leakage occurs in the printed portion, or poor adhesion of the ink to the base material occurs, causing the ink to be peeled off.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, completed the present invention. That is, in the present invention, when copolymerizing a silicone-based macromonomer and another radically polymerizable monomer, the entire amount of the silicone-based macromonomer is initially charged in a polymerization vessel, and the total amount of the other radically polymerizable monomer is charged. Alternatively, the method is a method for producing a graft copolymer, in which a part is gradually supplied into a polymerization vessel after the initiation of polymerization. The reason that the production method of the present invention is particularly useful as a method for producing a heat-resistance-imparting coating agent for a heat-sensitive transfer recording film is to prepare a silicone-containing graft copolymer by initially charging a silicone-based macromonomer. It is presumed that the polymerization rate of the silicone-based macromonomer having lower reactivity than the low-molecular-weight monomer was increased, and as a result, the content of the unreacted silicone-based macromonomer could be reduced. Hereinafter, the present invention will be described in more detail.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The silicone macromonomer used in the present invention has a radical polymerizable group such as a (meth) acryloyl group or a styryl group at one end of a linear silicone molecule. The number average molecular weight is the number average molecular weight in terms of polystyrene by gel permeation chromatography, and is 1,
000 to 100,000. If the number average molecular weight of the silicone-based macromonomer is less than 1,000, properties derived from silicone, that is, properties such as lubricity, are hardly exhibited. On the other hand, if it exceeds 100,000, the polymerizability of the silicone-based macromonomer is inferior and unreacted macromonomer tends to remain.

[0006] The silicone-based macromonomer can be produced by the following method. That is, as a production method utilizing an anionic polymerization method, a polymerization initiator such as lithium trialkylsilanolate is used, a cyclic trisiloxane or a cyclic tetrasiloxane is polymerized to obtain a silicone living polymer, and γ-methacryloyl There is a production method of reacting oxypropylmonochlorodimethylsilane and the like (for example, JP-A-59-78).
No. 236) and production methods utilizing a condensation reaction are disclosed in JP-A-58-167606 and JP-A-60-167606.
JP-A-123518 discloses a method for producing a silicone macromonomer by a condensation reaction of silicone having a silanol group at a terminal with γ-methacryloyloxypropyltrimethoxysilane or the like.

Other radical polymerizable monomers used together with the silicone macromonomer include (meth) acrylic monomers and / or styrene in that the obtained graft copolymer has excellent film-forming properties. It is preferably a main component, and specifically, the ratio of the (meth) acrylic monomer and / or styrene is preferably 50 to 100% by weight. Examples of the (meth) acrylic monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and t-butyl ( Alkyl (meth) acrylates such as meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate and isobornyl (meth) acrylate; hydroxyethyl (meth) acrylate;
Examples include hydroxyalkyl (meth) acrylates such as hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate, ethylene oxide-modified hydroxy (meth) acrylate, lactone-modified hydroxy (meth) acrylate, acrylic acid, and methacrylic acid.

[0008] A radical polymerizable monomer other than the (meth) acrylic monomer and styrene can be used if necessary. Examples of such a radical polymerizable monomer include (meth) acrylonitrile, vinyl acetate, and vinyl acetate. Organic silicon monomers such as (meth) acrylamide, itaconic acid, maleic acid, vinyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane, allyl methacrylate and diallyl phthalate are exemplified. The bifunctional monomers such as allyl methacrylate and diallyl phthalate are preferably used in such an amount that gelation does not occur during the production of the graft copolymer.

The preferred amount of the silicone macromonomer used to obtain the graft copolymer is 0.5 to 60% by weight based on the total amount of the silicone macromonomer and other radically polymerizable monomers. %, More preferably 15 to 50% by weight. If the proportion of the silicone-based macromonomer is less than 0.5% by weight, the properties of the silicone are hardly exhibited, while if it exceeds 60% by weight, the storage stability of the obtained graft copolymer tends to be insufficient.

In the present invention, the entire amount of the silicone-based macromonomer is charged into a polymerization vessel at the beginning of polymerization. The initial stage of the polymerization in the present invention means that the polymerization conversion rate of all the monomers is 10%.
Say within a period. Usually, the entire amount of the silicone-based macromonomer is charged into a polymerization vessel at a time before the start of the polymerization. If necessary, a part of the macromonomer is removed during the period in which the polymerization conversion rate of all the monomers is within 10% after the start of the polymerization. It may be supplied gradually inside. When the silicone-based macromonomer is supplied to the polymerization vessel when the conversion ratio of all the monomers exceeds 10%, if the obtained graft copolymer is used as a coating agent, the unreacted macromonomer is formed on the coating surface. Bleeding occurs and its use is limited. On the other hand, regarding the supply of other radically polymerizable monomers to the polymerization vessel, a part thereof is initially charged, and the remainder is gradually supplied after the start of the polymerization, or the entire amount is supplied after the start of the polymerization. be able to. After the initiation of the polymerization, the ratio of the other radically polymerizable monomer supplied into the reaction system is preferably 10 to 100% by weight of the total amount. If the ratio of the other radically polymerizable monomer supplied into the reaction system after the initiation of the polymerization is less than 10% by weight, the unreacted silicone-based macromonomer tends to remain.

As a polymerization method, a conventionally known method can be used, and a radiation irradiation method, a method using a radical polymerization initiator, and the like can be used. It is preferable from the viewpoint of easy control of the molecular weight of the copolymer, and specifically, any method such as a solution polymerization method using a solvent, a bulk polymerization method, and an emulsion polymerization method can be employed. As the radical polymerization initiator, any of an inorganic radical polymerization initiator and an organic radical polymerization initiator can be used, and may be appropriately selected depending on a polymerization method to be employed. Examples of the inorganic radical polymerization initiator include ammonium persulfate, sodium persulfate and potassium persulfate, and examples of the organic radical polymerization initiator include peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, Organic peroxides such as peroxydicarbonate and peroxyester, azobisisobutyronitrile and dimethyl-
Azo compounds such as 2,2'-azobisisobutyrate are exemplified. The amount of the polymerization initiator to be used is generally preferably from 0.01 to 10% by weight, more preferably from 0.1 to 5% by weight, based on the total weight of the polymerizable component. The temperature for the radical copolymerization is preferably from 50 to 150 ° C, more preferably from 60 to 100 ° C. The polymerization time is usually preferably 5 to 25 hours.

Solvents used for radical copolymerization by the solution polymerization method include acetone, methyl ethyl ketone,
Ketone solvents such as methyl isobutyl ketone, ethyl acetate, acetate solvents such as butyl acetate, benzene, toluene, aromatic hydrocarbon solvents such as xylene, cyclohexane, tetrahydrofuran, dimethylformamide,
Dimethyl sulfoxide, hexamethylphosphamide and the like are preferable, and a ketone solvent, an acetate solvent or an aromatic hydrocarbon solvent is more preferable. Since the organic solvent is a good solvent for the silicone macromonomer and the resulting graft copolymer, the amount of unreacted silicone macromonomer is reduced.

When the graft copolymer produced by the above method is used as a coating agent, it may be used in an unsaturated polyester resin, a fluorine resin or JP-A-49-12.
A curable composition such as polyester polyacrylate disclosed in Japanese Patent No. 0889 may be blended.
Based on the total amount of all resins in the coating agent, a preferable ratio of the above-mentioned additional resin is 50% by weight or less. Various additives such as fillers, various stabilizers and pigments may be added to the coating agent containing the above graft copolymer as a main component.Specifically, various silicas, calcium carbonate, magnesium carbonate, Titanium oxide,
Examples include iron oxide, glass fibers, dispersion stabilizers, antioxidants, antistatic agents, and ultraviolet absorbers.

The coating agent containing the above graft copolymer as a main component can be coated on the surface of a substrate such as rubber, plastic, metal, ceramics, glass, wood and paper. Specifically, back coating agents such as magnetic tapes / films, cassette sheets and thermal transfer recording films; release papers, masking tapes, adhesive tapes,
Release agents such as molds for confectionery cups, concrete, mortar, gorol and gypsum and stamping foils, and release agents for molding dies such as plastic and ceramic; magnetic cards, IC cards, cash cards, credit cards, prepaid cards And lubrication protective coatings for magnetic tickets, etc .; vehicles such as anti-graffiti paint, anti-paste paint, anti-fouling paint, anti-icing / condensation-preventive paint, and highly weather-resistant paint; Examples include a high weather resistance coating agent for wood, a polishing agent for leather, a water repellent and antifouling coating agent, and the like.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the following examples, “parts” indicates “parts by weight”. Further, the silicone-based macromonomer used in each example, that is, X-22-174D
X and AK-32 are both macromonomers having a methacryloyl group at one end of dimethylpolysiloxane.

Example 1 In a flask equipped with a stirrer, a condenser, a thermometer, a nitrogen inlet tube, and a liquid supply pump, a silicone macromonomer [trade name: X-22-1 manufactured by Shin-Etsu Chemical Co., Ltd.]
74DX, number average molecular weight 5,000] and 30 parts of methyl ethyl ketone were charged, and the temperature was raised to 70 ° C while bubbling nitrogen through. Then, a mixed solution of 40 parts of methyl methacrylate, 10 parts of butyl acrylate, 5 parts of 2-hydroxyethyl methacrylate, 5 parts of methacrylic acid, 10 parts of styrene and 1.5 parts of dimethyl-2,2'-azobisisobutyrate was added to 2 parts. The mixture was supplied to the flask over a period of time, and after supplying the whole amount, the mixture was further heated at 70 ° C. for 5 hours to synthesize a graft copolymer (1) solution having a solid content of 50%.

[0016]

Example 2 As a silicone macromonomer, a silicone macromonomer AK-32 manufactured by Toagosei Co., Ltd.
(Number average molecular weight 30,000), and 40 parts of the macromonomer, methyl methacrylate 10
, 20 parts of styrene and 100 parts of methyl ethyl ketone, and the temperature was raised to 70 ° C. while bubbling nitrogen through. Thereafter, a mixed solution of 10 parts of butyl acrylate, 10 parts of methyl methacrylate, 5 parts of 2-hydroxyethyl methacrylate, 5 parts of acrylic acid, and 1.2 parts of azobisisobutyronitrile was supplied over 3 hours. The mixture was further heated at 70 ° C. for 4 hours to obtain a graft copolymer (2) solution having a solid content of 50%.

[0017]

Comparative Example 1 In Example 1, the total amount of all the monomers and the polymerization initiator was charged all at once to the reaction flask before the start of the polymerization, and then heated at 70 ° C. for 7 hours while bubbling nitrogen. Polymerization was performed to obtain a graft copolymer (3) solution having a solid content of 50%.

[0018]

Comparative Example 2 The procedure of Example 1 was repeated except that the total amount of the silicone-based macromonomer, other radically polymerizable monomers and the polymerization initiator was gradually dropped into a polymerization medium heated to 70 ° C. Perform the same operation as in Example 1 to obtain a solid content of 50%.
% Of a graft copolymer (4) solution was synthesized.

The graft copolymer solution obtained in each of the above examples was diluted with methyl ethyl ketone to a solid content of 10%. The obtained diluted solution is coated on a polyester film having a film thickness of 50 μm with a bar coater, and dried.
A micron graft copolymer coating was formed. Using the obtained polyester film, the lubricity and releasability of the surface coated with the graft copolymer were evaluated by the following methods. (A) Lubricity Using a surface property measuring device manufactured by Shinto Kagaku Co., Ltd. at a temperature of 25 ° C.
The dynamic friction coefficient (μk) at a humidity of 60% RH was measured. The conditions for using the device are as follows. Contactor───Stainless steel ball with a diameter of 10 mm Load 荷重 100 g Moving speed──250 mm / min

(B) Release properties A KOKUYO cellophane tape (24 mm width) was pressed against the surface to be inspected, and the cellophane tape was pulled with a tensile tester at a pulling speed of 200 mm.
/ Min, temperature when peeled at an angle of 180 degrees 25
The tensile strength (g) at a temperature of 60 ° C. and a humidity of 60% RH was measured. The results of evaluating the lubricity and the releasability of the coating agent obtained in each of the above examples are as shown in Table 1.

A plurality of the above-mentioned polyester films coated with the graft copolymer were prepared, and they were stacked so that the coated surface and the non-coated surface were in contact with each other.
After applying the load of ² for 24 hours, 5 parts of a red dye (“MS Red G” manufactured by Mitsui Chemicals, Inc.) and a polyvinyl acetal resin [Sekisui Chemical S-Flex KS-
5 "] 3 parts of a mixed solvent of toluene / methyl ethyl ketone 9
The ink liquid dissolved in 2 parts was applied and dried to form an ink layer having a thickness of 5 microns. The heat-sensitive transfer film obtained by the above method was overlaid so that the ink-coated surface and the graft copolymer-coated surface were in contact with each other, and allowed to stand at 50 ° C. for 1 week with a load of 40 g / cm ² applied thereto. And the state of the obtained printing was evaluated.

(C) Printing conditions Printer @ POSTWOR manufactured by Casio Computer Co., Ltd.
D HX-1 Printing speed ── 5000 mm / min Printing mileage ── 1000 m Transferred paper の 上 Fine paper with a Beck smoothness of 50 seconds The evaluation results of printing are shown in Table 1 with symbols. The contents are as follows. ：: No print leakage and no extra print marks Δ: There is no printing leakage, but extra print marks are rarely generated. ×: There is no printing leakage, but there are extra print marks. ××: There are print omissions and extra print marks.

[0023]

[Table 1]

[0024]

According to the method for producing a graft copolymer of the present invention, the amount of unreacted silicone-based macromonomer can be reduced as compared with the conventional production method. The graft copolymer produced by this method is, of course, excellent in lubricity and releasability, but further minimizes contamination of the painted surface by unreacted silicone-based macromonomer, and is suitable as a lubrication and release coating agent. Which is particularly suitable as a thermal transfer recording film.

Claims (3)

[Claims] When the silicone-based macromonomer and another radically polymerizable monomer are copolymerized, the entire amount of the silicone-based macromonomer is initially charged into a polymerization vessel, and the total amount of the other radically polymerizable monomer or A method for producing a graft copolymer, characterized in that a portion is gradually supplied into a polymerization vessel after the initiation of polymerization. 2. The graft copolymer according to claim 1, wherein the proportion of the silicone-based macromonomer is 15 to 50% by weight based on the total amount of the silicone-based macromonomer and other radically polymerizable monomers. Production method. 3. A coating agent comprising the graft copolymer produced by the method for producing a graft copolymer according to claim 1 or 2.