JP2945468B2 - Polyacrylamide-based aqueous composition - Google Patents

Description

The present invention relates to a polyacrylamide-based aqueous composition.
More specifically, it relates to a polyacrylamide-based aqueous composition that can be suitably used as a coating type antistatic agent.

[Prior art] Thermoplastic resins such as polyolefin resins, ABS resins, and vinyl chloride resins have been widely used as materials for packaging and automobile parts as films and bags, but these thermoplastic resins have been widely used. Resins generally have high electrical resistance,
There is a serious drawback that it is easily charged by friction and sucks dust and the like.

Therefore, in recent years, as a method of imparting antistatic properties to a thermoplastic resin, for example, (a) a method of ionizing air in an environment in which the thermoplastic resin is used and increasing the humidity, and (b) a method of adding a conductive filler to the thermoplastic resin The most widely used methods include: mixing them, (c) modifying the surface of the thermoplastic resin by irradiating it with ultraviolet light, and (d) using an antistatic agent in the thermoplastic resin. Is the method (d).

The method of (d) further comprises: (e) a method of kneading a kneading type antistatic agent into a thermoplastic resin; and (f) spraying a coating type antistatic agent onto a processed product by directly spraying or the like. The method is roughly divided.

The method (f) is said to be superior to the method (e) from the viewpoints of workability at the time of processing and quick action of the antistatic effect.

Examples of the coating type antistatic agent used in the method (f) include (i) a long-chain aliphatic amine, a long-chain aliphatic amide, a phosphate, a quaternary ammonium salt, a polyoxyethylene alkylaryl ether, and a polyoxy A surfactant such as a sulfated product of ethylene alkyl aryl ether, sorbitan alkyl ester, or polyoxyethylene sorbitan alkyl ester dissolved in alcohol or the like; (ii) an aqueous solution of the surfactant; (iii) having antistatic properties An aqueous solution of a water-soluble polymer compound is known.

However, in the above-mentioned means (i), a solvent having a low boiling point is generally used in order to secure a drying speed in consideration of coating workability. However, in this method, the resin surface swells after coating, and the resin surface is swelled. There is a problem that fine cracks occur and the processed products adhere to each other when they come into contact with each other. As a solvent solution to solve such problems, isopropyl alcohol 10 to 15% by weight, normal hexane
Coating type antistatic agent for acrylic resin comprising 89.8 to 84.4% by weight and 0.2 to 0.6% by weight of quaternary ammonium salt
58-38730) has been proposed, but is not desirable in terms of air pollution and deterioration of the working environment because a solvent is used.

Although there is no problem in the working environment in the means of (ii),
Since it is an aqueous solution, the surfactant only adheres to the surface of the resin after drying, and since the molecular weight of the surfactant is at most about 500 to 700, a strong film is not formed. Therefore, there is a problem that the surfactant is easily peeled off due to friction or the like, and sufficient antistatic property is not provided.

In the means (iii), a film having excellent abrasion resistance is formed if the water-soluble polymer compound has an excellent film-forming ability. However, since the water-soluble polymer compound itself is water-soluble, it is water-resistant. And it is washed away during a washing step, and the antistatic ability is lost. Further, the aqueous solution of the water-soluble polymer compound has problems that the wettability to the resin is poor and the adhesion between the formed film and the resin is poor.

[Problems to be Solved by the Invention] Therefore, the present inventors have overcome the above-mentioned problems of the prior art, and have disclosed "Practical Handbook of Additives for Plastics and Rubber"
(Showa 62-2-20) "Performance required for a coating type antistatic agent" described on page 395 of Chemical Industry Co., Ltd., that is, (a) good durability against friction, washing with water, etc .; Good transparency; (c) no fine cracks on the resin surface;
And (d) assuring satisfactory heat resistance and chemical resistance, and conducting intensive research to find a composition that can be suitably used as an antistatic agent. As a result, a composition having all of these properties at the same time was obtained. We have finally found out and completed the present invention.

[Means for Solving the Problems] That is, the present invention provides an ethylene structural unit represented by the formula: CH ₂ —CH ₂ of 65 to 97 mol%, a general formula: (Wherein, R ¹ represents an alkyl group having 1 to 4 carbon atoms) 1 to 15 mol% of an acrylate structural unit represented by the following general formula: (Wherein R ² is an alkylene group having 2 to 8 carbon atoms, R ³ and R ⁴
Is an alkyl group having 1 to 4 carbon atoms, and R ⁵ is 1 to 4 carbon atoms.
An acrylamide structure represented by a 12 alkyl group, an arylalkyl group having 7 to 12 carbon atoms or an alicyclic alkyl group having 6 to 12 carbon atoms, and X represents a halogen atom, CH ₃ OSO ₃ or C ₂ H ₅ OSO ₃ ) The present invention relates to a polyacrylamide-based aqueous composition containing a linearly irregularly arranged acrylamide-based copolymer having a weight-average molecular weight of 1,000 to 50,000 comprising 1 to 30 mol% of units.

[Function and Examples] As described above, the polyacrylamide-based aqueous composition of the present invention has an ethylene structural unit represented by the formula: CH ₂ -CH ₂ of 65 to 97 mol%, and a general formula: (Wherein, R ¹ represents an alkyl group having 1 to 4 carbon atoms) 1 to 15 mol% of an acrylate structural unit represented by the following general formula: (Wherein R ² is an alkylene group having 2 to 8 carbon atoms, R ³ and R ⁴
Is an alkyl group having 1 to 4 carbon atoms, and R ⁵ is 1 to 4 carbon atoms.
An acrylamide structure represented by an alkyl group of 12; an arylalkyl group of 7 to 12 carbon atoms or an alicyclic alkyl group of 6 to 12 carbon atoms; X represents a halogen atom, CH ₃ OSO ₃ or C ₂ H ₅ OSO ₃ ) It contains an acrylamide copolymer having a weight average molecular weight of 1,000 to 50,000, which is linearly and irregularly arranged and has a unit of 1 to 30 mol%.

The proportion of the ethylene structural unit represented by the formula: CH ₂ —CH ₂ in the acrylamide copolymer is 65 to 97 mol%. When the proportion of the ethylene structural unit is less than 65 mol%, the softening point of the acrylamide-based copolymer becomes low, and the acrylamide-based copolymer becomes waxy in a temperature range usually used,
The durability against friction and the solvent resistance are deteriorated, and tack and stickiness are generated under high humidity, so that dust and the like easily adhere to the resin surface. The antistatic property of the copolymer becomes too small. In the present invention, the proportion of the ethylene structural unit is particularly preferably from 85 to 97 mol% from the viewpoint of balance between tackiness and antistatic property.

General formula in the acrylamide copolymer: (Wherein R ¹ is the same as described above), and the proportion of the acrylate structural unit is 1 to 15 mol%. When the proportion of the acrylate structural unit exceeds 15 mol%, the softening point of the acrylamide-based copolymer becomes low, and tackiness or stickiness occurs when applied to a thermoplastic resin, and dust and the like are formed on the resin surface. It becomes easy to adhere. In the present invention, since the acrylate structural unit is contained, the ability to form a film is increased, the adhesion to an acrylic resin or the like is improved, and as a result, the solvent resistance is increased. In the present invention, the proportion of the acrylate structural unit is from 1 to 15 mol%, preferably from 3 to 7 mol%, from the viewpoint of the balance between tackiness and solvent resistance.

In the acrylate structural unit, R ¹ has 1 to ¹ carbon atoms.
4 alkyl groups. Specific examples of such R ¹ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, n
-Butyl group and i-butyl group.
It may be mixed in the molecule. Among these groups, a methyl group and an ethyl group are particularly preferable because they do not cause adverse effects due to stickiness.

General formula in the acrylamide copolymer: (Wherein R ² , R ³ , R ⁴ and R ⁵ are the same as described above), and the proportion of the acrylamide structural unit is 1 to 30 mol%. When the proportion of the acrylamide structural unit is less than 1 mol%, the antistatic property becomes too small, and
If the molar percentage is exceeded, moisture absorption occurs when applied to a thermoplastic resin, causing a whitening phenomenon, which greatly reduces transparency, deteriorates water resistance, and further increases tackiness due to tack. Will occur. In the present invention, the proportion of the acrylamide structural unit is particularly preferably 3 to 15 mol% from the viewpoint of balance between antistatic properties, water resistance, transparency and adhesiveness.

In the acrylamide structural unit, R ² is an alkylene group having 2 to 8 carbon atoms. Specific examples of such R ^2, for example, ethylene group, propylene group, hexamethylene group, etc. neopentylene group, and these groups may coexist in a molecule. Among these groups, an ethylene group and a propylene group are preferable from the viewpoint of easiness of production and economy, and a propylene group is particularly preferable.

R ³ and R ⁴ are each an alkyl group having 1 to 4 carbon atoms. Specific examples of such R ³ and R ⁴ include a methyl group, an ethyl group, a propyl group, and a butyl group, and these groups may be present in one molecule. Of these groups, a methyl group and an ethyl group are preferred from the viewpoint of antistatic properties.

R ⁵ is an alkyl group having 1 to 12 carbon atoms, an arylalkyl group having 7 to 12 carbon atoms, or an alicyclic alkyl group having 6 to 12 carbon atoms. Specific examples of such R ^5, such as methyl group, ethyl group, n- propyl group, i- propyl, n-
Alkyl groups such as butyl group, sec-butyl group, n-octyl group and n-lauryl group; arylalkyl groups such as benzyl group and 4-methylbenzyl group; cyclohexyl group;
An alicyclic alkyl group such as a methylcyclohexyl group may be mentioned, and these groups may be present in one molecule. Incidentally, as the R ^5, from the viewpoint of adhesiveness, preferably Chakukusarijo alkyl and arylalkyl groups and the lower alkyl group is preferred from the viewpoint of antistatic property. As particularly preferred R ^5, include the methyl and ethyl groups.

X is a halogen atom such as Cl, Br, I, etc.
CH ₃ OSO ₃ or CH ₂ H ₅ OSO ₃ , which may be present in one molecule. Among these, Cl, CH ₃ OSO _{3 and} C ₂ H ₅ OSO ₃ are preferred from the viewpoint of antistatic properties.

The weight average molecular weight of the acrylamide copolymer is
It is 1000-50000. When the weight average molecular weight is less than 1,000, the molecular weight becomes too small and the film forming ability is inferior, the durability against friction and the like intended by the present invention, the solvent resistance is not sufficiently exhibited, and 50,000 If the ratio is more than 3, the viscosity at the time of dispersing, emulsifying, or solubilizing the acrylamide-based copolymer in water becomes too large, resulting in poor workability. Preferred weight average molecular weight is 3000-30
000.

The term “weight average molecular weight” as used herein refers to a monodisperse weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

The acrylamide-based copolymer cannot be easily measured because it is hardly soluble in an ordinary gel permeation eluent such as tetrahydrofuran (THF) or xylene, but the ultra-high temperature GPC method (Kinukawa, Journal of Polymer Science, 44
Volume 2, No. 2, pp. 139-141 (1987)).

The acrylamide-based copolymer used in the present invention is, for example, an ethylene-acrylate copolymer obtained by copolymerizing ethylene and an acrylate by a high-pressure polymerization method described in, for example, JP-A-60-79008. The resulting ethylene-acrylic acid ester-acrylic acid copolymer is amidated with N, N-dialkylaminoalkylamine and then quaternized with a quaternizing agent. It can be obtained by denaturing with kaotin.

The aqueous composition of the present invention is obtained by blending the acrylamide copolymer, but when blended,
The acrylamide copolymer is dispersed, emulsified or solubilized in water.

The method for dispersing, emulsifying, or solubilizing the acrylamide copolymer in water is not particularly limited. One example is a high-pressure emulsification method employed in producing a normal polyethylene emulsion. That is, there is a method in which an acrylamide-based copolymer, water and, if necessary, a surfactant are charged into a high-pressure vessel equipped with a mechanical stirring device such as an autoclave and heated while stirring.

The surfactant is preferably a nonionic or chaotic surfactant. Anionic ones are not preferred because they form a complex ionically with the acrylamide-based copolymer exhibiting chaotic properties and are insoluble in water.
The acrylamide copolymer used in the present invention itself has emulsifying power, and thus does not necessarily require a surfactant.

When a large amount of the surfactant is used, a decrease in durability is caused when the obtained aqueous composition is used, and since it becomes tacky, usually 100 parts by weight of an acrylamide-based copolymer The amount of the surfactant used is preferably 25 parts by weight or less, more preferably 20 parts by weight or less.

After charging the acrylamide copolymer, water and a surfactant in a high-pressure vessel, the heating temperature is usually 5 to 20 ° C. higher than the temperature at which the acrylamide copolymer melts.
It is preferred to carry out at a high temperature, i.e. 60-200 <0> C. The heating temperature differs depending on the heating temperature.
About one minute to one hour is sufficient. If the heating temperature is too low and the heating time is too short, a precipitate will form over time, resulting in a poorly stable composition, and if the heating temperature is too high and the heating time will be long. If it's too long, it's not only economically disadvantageous,
Hydrolysis of the acrylamide copolymer occurs.

The proportion of the acrylamide-based copolymer in the aqueous composition of the present invention is not particularly limited, and may be appropriately adjusted depending on the purpose and application of the aqueous composition of the present invention. 5 to 40 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the aqueous composition.

The aqueous composition of the present invention may optionally contain an antifoaming agent, a thickener, and the like, depending on the use and the like.

The reason that the thus obtained aqueous composition of the present invention is well-dispersed, emulsified, and solubilized in water without any particular limitation and has excellent storage stability is not clear, but is probably not an acrylamide copolymer. Hydrophobic ethylene structural units and acrylate structural units and hydrophilic acrylamide structural units are distributed in one molecule in a well-balanced manner and exist in water as a high molecular weight surfactant. It is guessed.

Next, the aqueous composition of the present invention and examples will be described in more detail, but the present invention is not limited to these examples.

Examples 1 to 7 and Comparative Examples 1 and ₂ An ethylene structural unit represented by the formula: CH ₂ —CH ₂ , a general formula: An acrylate structural unit represented by the general formula: An acrylamide copolymer comprising an acrylamide structural unit represented by Where R ¹ , R ² , R ³ , R ⁴ ,
R ⁵ and X and the amount of ethylene structural units, the amount of acrylate structural units and the amount of acrylamide structural units
It is as shown in Table 1.

Next, aqueous compositions were obtained from the respective acrylamide copolymers under the conditions shown in Table 2. The manufacturing equipment is made of glass autoclave TEM-V-1000, manufactured by Pressure Glass Industry Co., Ltd.
Type used. As physical properties of the obtained polyacrylamide-based aqueous composition, viscosity, particle size, pH, conductivity, transparency and friction durability were examined according to the following methods. The results are shown in Table 2.

[Viscosity] After the obtained polyacrylamide-based aqueous composition was allowed to stand in a constant temperature room at 25 ° C for 24 hours, the viscosity was measured at 60 rpm (25 ° C) using a BM type viscometer manufactured by Tokimec Co., Ltd.

[Particle Size] The particle size was measured using DLS-700 manufactured by Otsuka Electronics Co., Ltd. The measurement and analysis conditions are as follows.

 (Light source): 5mW He-Ne laser (Temperature): 25 ° C (Measurement angle): 90 ° (Solvent): Water (Analysis method): Histogram method [pH] 25 ° C with the aqueous composition as it is Was measured.

[Conductivity] A polyethylene terephthalate (hereinafter, referred to as PET) film was applied using a bar coater so that the adhesion amount of the acrylamide copolymer was 2.5 / m ^2, and dried overnight at room temperature. Dry with air at 2 ° C for 2 minutes.
I got an ET film. After leaving this conductive PET film in an atmosphere of 20 ° C. and a relative humidity of 50% for 48 hours, the resistance was measured using a super-insulation meter (SM-10E) manufactured by Toa Denpa Co., Ltd.

[Transparency] The transparency of the film used for measuring the conductivity was visually determined. ○ means good transparency, and X means no complete transparency.

[Friction durability] Acrylic amide copolymer was applied to a polyethylene plate at 2.0 g / m ² , dried overnight at room temperature, and air-dried at 105 ° C for 2 hours at 20 ° C. Relative humidity 65
% For 48 hours to obtain a test piece. Height 2cm
The test piece was rubbed with absorbent cotton, immediately placed on the petri dish, and the state of adhesion of the ash was observed. The friction durability was evaluated by the number of times of friction when ash was attached. The higher the number of times of friction, the better the durability.

Comparative Example 3 A 20% by weight aqueous solution of lauryldimethylbenzylammonium chloride was prepared as a conventional coating type antistatic agent. The conductivity, transparency and friction durability of the obtained aqueous solution were tested. Table 2 shows the results.

As is clear from the results shown in Table 2, it is understood that the aqueous compositions obtained in Examples 1 to 7 of the present invention are all excellent in friction durability.

[Effect of the Invention] The polyacrylamide-based aqueous composition of the present invention imparts excellent antistatic properties as a coating-type antistatic agent, and has various properties due to its excellent transparency and durability due to friction. Can be widely used as an antistatic agent for the above resin.

────────────────────────────────────────────────── (5) Continuation of the front page (51) Int.Cl. ⁶ Identification code FI C08F 220: 60) (56) References JP-A-63-57609 (JP, A) JP-A-2-269715 (JP, A) JP-A-59-91102 (JP, A) JP-A-1-314729 (JP, A) JP-A-63-304010 (JP, A) JP-A-4-198308 (JP, A) (58) (Int.Cl. ⁶ , DB name) C08F 10/02 C08F 210/02 C08F 20/10-20/18 C08F 220/10-220/18 C08F 20/54-20/60 C08F 220/54-220/60 CA (STN)

Claims (1)

(57) [Claims] (1) An ethylene structural unit represented by the formula: CH ₂ —CH _{2 (} 65-97 mol%), a general formula: (Wherein, R ¹ represents an alkyl group having 1 to 4 carbon atoms) 1 to 15 mol% of an acrylate structural unit represented by the following general formula: (Wherein R ² is an alkylene group having 2 to 8 carbon atoms, R ³ and R ⁴
Is an alkyl group having 1 to 4 carbon atoms, and R ⁵ is 1 to 4 carbon atoms.
12 alkyl group, acrylamide structure alicyclic alkyl group having 6 to 12 arylalkyl group or a carbon number of 7 to 12 carbon atoms, X is represented by a halogen atom, a CH ₃ OSO ₃ or C ₂ H ₅ OSO ₃₎ A polyacrylamide-based aqueous composition comprising a linearly irregularly arranged acrylamide-based copolymer having a weight-average molecular weight of 1,000 to 50,000 comprising 1 to 30 mol% of units.