JPS6124401B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a photocrosslinkable polymer dispersion, and particularly to a method for producing a reactive polymer dispersion containing a sensitizer.

In the past, many patents and papers have been published regarding methods for producing photocrosslinkable polymers, and several methods have been proposed, including methods using polymer reactions, vinyl polymerization reactions, and condensation reactions. There is.

In particular, recently, polymerization reactions using aqueous solvents have been studied in the fields of resins for paints, sizing agents for paper stocks, etc., in order to prevent drainage and to prevent the diffusion of organic solvents into the atmosphere.

By the way, when using a composition containing a photocrosslinkable polymer, a sensitizer is usually added to the composition to form a coating film, which is then photocrosslinked to make it insolubilized. Therefore, there has been a need to develop a method for producing a composition that effectively increases the photocrosslinking rate and uses an aqueous solvent.

The present inventor has discovered that by utilizing aqueous polymerization techniques such as suspension polymerization and latex polymerization of vinyl monomers having photocrosslinkable groups, it is possible to substantially eliminate the use of organic solvents, and furthermore, discovered that by allowing the sensitizer to exist in the organic phase, that is, the monomer phase, a reactive polymer dispersion containing the sensitizer and having excellent properties as a photocrosslinkable polymer could be obtained. Ta.

The objects of the present invention are as follows. First, it provides a reactive polymer dispersion synthesized using an aqueous solvent. Second, a dispersion of reactive polymer particles containing a sensitizer is provided.
The third object is to provide a reactive polymer dispersion containing an oil-soluble sensitizer and, if necessary, a colorant.
The fourth object is to provide a reactive polymer dispersion liquid useful for paints, printing inks, printing plates, etc. Fifth
Another object of the present invention is to provide a reactive polymer dispersion that, when coated and dried as it is after the completion of the polymerization reaction and exposed to light, only the exposed portion becomes insolubilized in a solvent.

The above-mentioned object of the present invention is to disperse a lipophilic sensitizer, a vinyl monomer having a photocrosslinkable group, and a vinyl monomer having no photocrosslinkable group as an organic phase in an aqueous solvent; Next, the monomer is polymerized to form a reactive polymer having a photocrosslinkable group, thereby obtaining a reactive polymer dispersed in an aqueous solvent. effectively achieved. Note that a coloring agent may be present in the organic phase if necessary.

The components, steps, etc. used in the present invention will be explained in detail below.

The photocrosslinkable group refers to a group having an unsaturated double bond, particularly one derived from an unsaturated acid, an unsaturated carbonyl compound, an azide compound, an allyl compound, a stilbene type compound, and the like.

For specific examples of these, see, for example, J.A. J.Kosar “Light Sensitive Systems”
John Willey and Sons
Wiley & Sons). Detailed in the 1965 publication. Among them, in order to effectively obtain a reactive polymer dispersion having a photocrosslinkable group in the side chain without participating in the vinyl polymerization reaction, it is necessary to The most advantageous are photocrosslinkable groups. As the substituent at the β-position, a chain or cyclic unsaturated group, particularly an aromatic group, is most preferable. Two or more of these may be present in the vinyl monomer.

The vinyl monomer refers to an addition polymerizable monomer having one vinyl or vinylidene group. These include acrylic esters, methacrylic esters, or amides thereof, vinyl aromatic compounds,
It refers to any form such as vinyl ether or vinyl ester. Among these, acrylic esters and methacrylic esters are advantageous in terms of reactivity, ease of synthesis, and availability.

A method for synthesizing vinyl monomers having photocrosslinkable groups is detailed in the patents cited below.

Examples of the vinyl monomer having a photocrosslinkable group in the present invention include those represented by the following formula.

Here, R ₁ is a hydrogen atom or an alkyl group, and X is a divalent group such as an ester bond, an ether bond,
The group containing an amide bond or the like, Y, represents the above-mentioned photocrosslinkable group. Particularly preferred X has 2 to about 10 carbon atoms. Compounds in which X has one or less carbon atoms, such as vinyl cinnamate, do not give good results. As a specific example of these, the inventors have already filed Japanese Patent Application No. 118-118-984 (West German Patent No.
625), JP-A No. 49-36794, JP-A No. 49-38987, JP-A No. 49-
60390, 49-103975, 49-107226, acrylate or methacrylate with β-aryl substituted acrylate group, styrene with azido group, acrylate or methacrylate with β-aryl acrylate group, vinyl cinnamic acid or its derivatives, vinyl ethers with δ-aryl substituted pentadienoate groups, acrylates or methacrylates. One or more of these may be used.

Among these, acrylates are the most convenient.

In addition, these photocrosslinkable vinyl monomers account for approximately 10% or more and 60% by weight of the obtained polymer.
Depending on the purpose, it may be copolymerized with one or more types of ordinary vinyl monomers.

For example, these include vinyl aromatic compounds, derivatives of acrylic acid or methacrylic acid,
Examples include acrylonitrile, diene compounds, vinyl esters, and vinyl ethers.

If hardness is required as a coating when applied and used, a material selected from methyl methacrylate, styrene, acrylonitrile, etc.
It is convenient to copolymerize to about 60% by weight, and for applications that require flexibility, copolymerize acrylic acid alkyl ester, butyl methacrylate, butadiene, etc. to about 10 to 60% by weight. It is convenient to do so. In addition, in fields that require strong adhesion to the coated surface, carboxy,
It is convenient to copolymerize monomers having functional groups such as hydroxy, N-methylol, amide, and epoxy in an amount of 0.2 to 20% by weight.
Needless to say, these combinations and quantitative relationships can be changed widely depending on the application. Also, strong
When it is desired to obtain a reactive polymer in the form of particles that are poorly soluble in solvents, it is also possible to use a monomer that easily causes gelation, such as polyacrylate or polymethacrylate of polyol.

Furthermore, as the polymerization method, radical polymerization is most convenient, and azo compounds, peroxides, redox initiators, etc. are used.

For information on polymerization reaction methods, initiator concentrations, reaction temperatures, times, additives, etc., please refer to the Encyclopedia of Polymer Science and Technology.
and Technology)” Interscience Pub.

Regarding the monomer concentration, it is particularly preferable to set the solid content concentration to about 20 to 50% by weight after the completion of the polymerization reaction, in view of the subsequent use.

In addition, sensitizers that can be dissolved in an aqueous solvent, such as methyl ethyl ketone, benzene, etc., have a difference in the distribution coefficient to the phase occupied by the vinyl monomer, that is, the organic phase, and that to the aqueous phase. 5% by weight or more) and are lipophilic. When a hydrophilic sensitizer is used, it is not effectively incorporated into the polymer particles during the polymerization reaction, and even when applied as a reactive polymer, it exists locally, resulting in a photocrosslinking rate. This is undesirable as it causes unevenness. Regarding sensitizers, see Chapters 4 and 5 of the above-mentioned book by Kosar, and among them, those that do not inhibit radical polymerization reactions are preferred. For example, it depends on the skeleton, but compared to aromatic quinones and aromatic nitro compounds,
More advantageous are aromatic ketones, asiloin or asiloin ether. To check whether a sensitizer inhibits radical polymerization, dissolve or disperse about 5% by weight of the sensitizer in methyl methacrylate and hold it at 70℃ for about 1 hour in a nitrogen gas atmosphere using an azo compound as an initiator. can be easily determined by bulk polymerization.

Among these, benzoin ethers (alkyl or aralkyl ethers having 1 to about 8 carbon atoms) are particularly useful in the present invention, and when aromatic quinones and aromatic nitro compounds are used, the conversion rate of vinyl monomers is low. It is desirable to add it when it reaches 80% or more.

These sensitizers are used in an amount of about 1 to 20% by weight, preferably about 3 to 8% by weight of the produced polymer.

As an aqueous solvent, water or about 20% by weight thereof
Refers to products to which polar or non-polar organic solvents of a certain degree or less have been added, as well as fruit surface active agents, thickeners, antistatic agents, plasticizers, PH indicators, acids or bases, ultraviolet absorbers, and fluorescence enhancers. Whitening agents, magnetic materials, etc., such as polyoxyethylene alkyl sulfate soda salt, polyoxyethylene aryl sulfate sodium salt, polyoxyethylene alkyl sulfate phosphate, polyvinyl alfur,
CMC, nonylphenoxy polyethylene oxide, sorbitan laurate, etc. may also be included.

The reactive polymer dispersion obtained in this way contains a sensitizer in the polymer particles, so even if it is applied as it is or after being separated by spray drying, it will not react to the light when it forms a film. The advantage is that the crosslinking rate is significantly faster.

Further, during the above polymerization reaction, organic or inorganic colorants such as white to colored pigments such as titanium dioxide, cobalt oxide, phthalocyanine blue,
About 5 to 60% by weight of zinc oxide, selenium sulfide, carbon black, etc. can also be used together.
When a coloring agent is added in this way, there is an advantage that only the exposed areas remain in a colored state when a coating film is subjected to a photocrosslinking reaction and developed.

Further, when photo-crosslinking the reactive polymer dispersion of the present invention, ordinary electromagnetic waves or particle beams such as sunlight, ultraviolet lamps, mercury lamps, laser beams, etc. are effective, and imagewise exposure is also effective. I can't help it.

Examples will be described below.

Example 1 β-cinnamoyloxyethyl acrylate 2
g, methyl methacrylate 2g, butyl methacrylate 2g, benzoinhexyl ether 0.1
g and 0.04 g of azobisisobutyronitrile were weighed out and dispersed in 10 g of water in which 2 g of sodium hydrogen phosphate and 0.1 g of polyvinyl alcohol were dissolved. Stir vigorously while passing nitrogen gas through this,
It was held at 70-85°C for 30 minutes. In this way, a reactive polymer dispersion containing a sensitizer was obtained.

Example 2 β-cinnamoyloxyethyl acrylate 10
g, 5 g of methyl methacrylate, 4 g of ethyl acrylate, 0.5 g of acryloxypropionic acid, and 1 g of benzoin methyl ether were dispersed in 50 ml of water in which 0.3 g of nonylphenoxypentaethyleneoxybutanesulfonic acid sodium salt was dissolved. While passing nitrogen gas, the mixture was stirred vigorously and maintained at 65° to 80°C for 25 minutes. Then, 0.3 g of Michler's ketone was added and the mixture was further maintained at 60° C. for 15 minutes. In this way, a reactive polymer dispersion was obtained.

Example 3 Nonylphenoxypolyethylene oxyphosphate 0.15g, nonyloxypolyethyleneoxysulfate sodium salt 0.2g, sodium sulfite 0.015
g was dissolved in 10 ml of water. This was heated and stirred at 65°C to 75°C while nitrogen gas was passed through it, and the following solutions A and B were separately added dropwise at the same time.

Solution A: 0.05g of ammonium persulfate dissolved in 3ml of water.

Solution B: 1 g of β-styrylacryloxyethyl acrylate, 3 g of β-cinnamoyloxyethyl acrylate, 3 g of methyl methacrylate, 2 g of butyl acrylate, 1 g of benzoin ethyl ether, and 1 g of titanium dioxide were thoroughly stirred.

The dropwise addition was completed in 15 minutes, and the temperature was maintained at 65 to 75°C for about 1 hour.

The reactive polymer dispersion thus obtained was applied onto an anodized aluminum plate to a dry film thickness of 2 μm. Then, from a distance of 30cm, 450W
When irradiated for 2 minutes using a high-pressure mercury lamp, the irradiated area became insoluble in the organic solvent.

Claims (1)

[Claims] 1. A lipophilic sensitizer, a vinyl monomer having a photocrosslinkable group, and a vinyl monomer not having a photocrosslinkable group are dispersed as an organic phase in an aqueous solvent, and then the monomers are dispersed as an organic phase. 1. A method for producing a reactive polymer dispersion, which comprises polymerizing to form a reactive polymer having a photocrosslinkable group and obtaining a reactive polymer dispersed in an aqueous solvent.