JPS5829832A - Production of synthetic resin molding having excellent non-drippedness - Google Patents

Abstract

PURPOSE:To obtain a film or the like which is resistant to dripping of water drops for a ling time, is freed from mist formation at night and is useful in agricultural houses or the like, by treating a synthetic resin film or the like with an aqueous solution containing colloidal silica and a small amount of a surfactant. CONSTITUTION:A non-dripped molding is prepared by immersing a synthetic resin molding (e.g., film, sheet, plate) made of PE, PVC or the like, in an aqueous solution of surface tension 17-75dyn/cm containing 0.05-20wt% colloidal silica and 1X10<-4>-1.0wt% cationic surfactant (e.g., compound of the formula, wherein R is 8-18C alkyl and X is Cl or Br) and/or an amphoteric surfactant to deposit the colloidal silica particles on the surface of the molding and, if necessary, rinsing the molding with water or the like, and drying the molding. Instead of immersion, spraying of an aqueous solution can be used. EFFECT:Non-drippedness can last for six months or longer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing synthetic resin molded articles having excellent drop-free properties, such as synthetic resin films, sheets, and plates. In this specification, "dropless property" refers to the property that water droplets do not adhere to the surface of a synthetic resin molded product, and "dropless agent" refers to an agent that imparts dropless properties to a synthetic resin molded product. .

The surface of synthetic resin molded products such as polyethylene, polypropylene, polyvinyl chloride, polyester, and polymethyl methacrylate cape is hydrophobic and has little affinity for water, so water droplets easily adhere to it. For example, when a synthetic resin film or sheet floor is used for an agricultural greenhouse, water vapor evaporating from the soil or crops can be absorbed by the film or sheet floor. !
Water droplets are formed by condensation on the surface. As a result, films and sheets become opaque, the transmittance of sunlight decreases, the growth of crops is hindered, and rope rot occurs due to falling water droplets.

Conventionally, in order to prevent water droplets from adhering to such synthetic resin moldings, it has been necessary to knead a hydrophilic polymer compound in various surfactants into the synthetic resin before molding, or to apply it to the surface of the synthetic resin molding. A coating method is used. However, the synthetic resin molded products obtained by these methods have the disadvantage that their drip-free properties last for only a few months, and those with good drip-free properties can be used in greenhouses from evening to night. There were drawbacks such as the generation of haze, which could cause disease outbreaks. and,
In general, the better the drip-free property, the more significant the mist generation, so it is presumed that the cause of the mist generation is as follows. In other words, at night, the temperature of the ground is higher than the surrounding air, and the water vapor that evaporates from the ground is cooled by the air.
It becomes 1 drop. On the other hand, a water film is formed on the inner surface of the film or sheet used in greenhouses due to the non-droplet effect, but the surface of this water film contains surfactant dissolved in it, and - This prevents the droplets from condensing into a water film, causing the fog droplets to accumulate inside the greenhouse and form a mist.

It has already been proposed to use a mixture of an inorganic aqueous sol and a surfactant as a type of non-droplet coating agent. For example, a surfactant is the main ingredient with a small amount of silica sol added to it (Special Publication ShojO-//3≠No. 1 Publication), and a surfactant is added to an alkaline sol (Special Publication Sho≠Tar3. 2
66g publication), alumina sol with surfactant and hydrophilic polymer added (Japanese Patent Application Laid-open No. 7277)
, one in which a hydrophilic polymer and a surfactant are added to colloidal silica (JP-A-Sho, to-3r3.z), and one in which a surfactant is added to silica sol (JP-A-Sho 3!-, t4/
No. 77, Japanese Unexamined Patent Publication No. 44'-JO 77), etc. were proposed.

Although the surfactant concentration is considerably reduced in the products described in these publications, in many cases there are still 0.00 to 0.00% in the coating type non-droplet agent.
/, 96 or more, and usually contains a much larger amount of surfactant, and when coating and drying them,
Since the surfactant contained remains, a mist is generated. This reduces the surface tension of the coating solution to 37 d/d to wet low energy surfaces such as polyethylene film.
It is necessary to lower the surface tension of the non-droplet agent to below α level, and in each of the above publications, it is necessary to lower the surface tension of the non-droplet agent to wet the plastic surface, and to apply the non-droplet agent to both surfaces of the plastic. This makes it possible. Moreover, this type of spray-on type non-drop agent generally requires the presence of a surfactant with a weight of 0.7 or more, but usually with a much higher current, especially in roll coating methods. It has been considered desirable to add a surfactant at a significantly high concentration in order to coat plastic films and sheets uniformly and continuously at high speeds using an industrially advantageous method. Some of the examples in the above-mentioned publication have a surfactant concentration of 0.7% by weight or less, but the coating method in all such cases is limited to spray coating, which is industrially disadvantageous.

Additionally, it has already been reported that when a polyethylene or Tefune film is placed in an aqueous sol of tin hydroxide in iron hydroxide, colloidal particles are deposited on the surface of the film, making it wettable in water [Journal] φOp Colloid and Interface Science Vol≠Co, No.
J31-J91sc/Ref. 1973]. However, according to the circular, in order to soak a polyethylene film in iron hydroxide sol or tin hydroxide sol to deposit colloidal particles on the film surface so that it becomes wet with water, 2.
It is said that it is necessary to soak for 0 minutes or 0.2j minutes. Previously, the present inventor actually produced a polyethylene film on which these colloidal particles were deposited using this method and measured its performance using it in a commercial greenhouse, and found that it was completely impractical in the following respects. There was found.

That is, the film gets wet with liquid water, but when used in agricultural greenhouses and does not come into contact with water vapor, it becomes cloudy.

Particularly in winter, when the amount of water vapor transpiration is low, significant cloudiness persists for a long period of time.

It was found that this was caused by the fact that the density of the colloidal particles on the film surface was low, and the surface of polyethylene was calculated between the colloidal particles. In other words, when it comes into contact with liquid water, even if there is a large exposed area of the polyethylene surface, the water spreads out as a liquid film and wets the film, but the water vapor condenses on the film surface as small droplets, and the polyethylene It is repelled by the 11 projections on the surface and remains as droplets, giving it a cloudy appearance. To improve this, K must be deposited on the surface of the polyethylene film to increase the density of the nine colloidal particles, and K, which imparts droplet-free properties that do not cloud with water vapor, can be added to the polyethylene film by iron hydroxide or tin hydroxide. It was found that it is not a method that can be implemented industrially since it is necessary to immerse the material in the aqueous sol for preferably about 30 minutes during lj sorting.

The inventors of the present invention aimed to reduce the I.
The present invention was achieved as a result of various research in order to produce a synthetic resin molded product that uses a grade I surfactant, enables industrially advantageous coating, and maintains drip-free properties for a long period of time. It is something.

That is, the method for producing a synthetic resin molded article with excellent drop-free properties according to the present invention uses colloidal silica of 0.0! -20111-96, a synthetic resin molded article is immersed in an aqueous liquid containing a cationic surfactant and/or an amphoteric surfactant/X/0-4 to 7.0% by weight, or the aqueous liquid is sprayed. This method is characterized in that colloidal silica particles are deposited on the surface of the synthetic resin molded article.

The colloidal silica in the present invention is O,OS”
An aqueous liquid containing a cationic surfactant and/or an amphoteric surfactant at ~2θ weight /×70~/ and a θ superposition of 9 (hereinafter sometimes simply referred to as a “deposition liquid”) is preferably Colloidal silica content is 0. Oj −0,
/ The weight of the liquid is 9, and the surface tension of the liquid is 77 ~
7J Dia / OR, preferably 3! ~70 dynes/
The things in my mouth are coming out.

If the silica concentration is less than o or ozx*s, deposition will be difficult to occur, and if the silica concentration is 1.20 weight or more, the stability of the liquid will be compromised and deposition treatment will be difficult.

If the surfactant concentration is less than /X/0=weight t96, silica deposition will be difficult to occur, and if it is greater than /,O weight 9, the deposited liquid will coagulate, resulting in poor storage stability and making deposition treatment difficult. Become.

Furthermore, if the surface tension is greater than 7j dynes/3, the compatibility with the synthetic resin is poor and deposition occurs, resulting in K<. In terms of processing synthetic resin moldings, the lower the surface tension, the better, but in order to create a state that causes deposits, 77 dynes/4:FJ1
This usually amounts to 33 dies/crn or more.

When a synthetic resin molded article is immersed in such a deposition solution of the present invention, silica particles are deposited on the surface of the synthetic resin molded article in a high density (finely) almost instantaneously, within about λO seconds at the latest. do. Then, dry the deposited surface and turn it into water vapor! Even when touched, no clouding was observed, showing excellent drip-free properties. Previously, it has been reported that positively charged alumina sol is deposited in a short time on a hydrophilic, negatively charged surface like glass, but on a hydrophobic, electrically neutral or electrically neutral surface like polyethylene, The almost instantaneous deposition of silica sol on a near-neutral surface is completely unexpected and surprising.

At first glance, the deposition liquid used in the present invention is similar to a conventional silica sol or alumina sol with a surfactant added thereto, but in reality, the two can be clearly distinguished in the following points. It is.

(1) Conventional spray-on type non-drop agents are applied by adding a relatively polyelectrolytic surfactant to lower the surface tension to 37 dynes/cnM degrees or less and wetting the surface of the synthetic resin.

In contrast, the deposition solution of the present invention has a relatively low surfactant concentration and a surface tension of 77-7! Die; y/an, preferably 35-70 dynes/C
Even if you try to apply it to the surface of a polyethylene film using a roll coater method or a brush mc method, it will be repelled and cannot be applied, so it can only be applied by spraying and dipping methods. At least it can be applied.

(il) When a conventional spray-on type non-drop agent is applied to the surface of a synthetic resin molded product and immediately rinsed with water, the colloid particles are washed away and the product returns to its water-repellent state.

On the other hand, even if a synthetic resin molded article is immersed in the deposition solution of the present invention for a few seconds, then taken out and immediately rinsed with water, the surface of the synthetic resin molded article will still be rinsed with water and deposited. Colloidal silica is not washed away by water.

Thus, the deposition solution in the present invention contains 0.06 to 20 Iiflk of colloidal silica, preferably 0.7 to 20 Iiflk.
j weight 9, cationic surfactant and/or amphoteric surfactant lX10-4 ~/, 0 weight 9, preferably 0.0 j ~ 0. /t 1%,
Usually, it is easily prepared by mixing a dilute aqueous solution of the above-mentioned surfactant with silica sol diluted with water.

Generally, when a cationic surfactant or an amphoteric surfactant is added to silica sol, the charge on the silica is neutralized, causing precipitation or gelation, but when the surfactant is added at a relatively low concentration, The deposition solution of the present invention is in a state where almost no sedimentation occurs or it is only slightly cloudy. Furthermore, even if some precipitation occurs, it will not have any adverse effect on the deposition properties or drip-free properties. However, in that case, the transparency of the film etc. after the treatment is reduced to some extent, but this can be easily solved by subsequently rinsing the film thickness after the immersion treatment with water.

As the surfactant in the deposition solution of the present invention, cationic surfactants, amphoteric surfactants, and mixtures of both are used. The surfactant may be of any type as long as it is a cationic surfactant and/or an amphoteric surfactant. Examples of the cationic surfactant include alkylamine salts, alkylammonium salts, and alkylpyridinium salts. I can gain momentum. Examples of surface active agents include betaine type surfactants, glycine type surfactants, and sulfuric surfactants.
9 x x Chill salt type, sulfonic acid type, and phosphate ester type are listed.

These surfactants may be used in combination in amounts of 2M or more.

The alkyl group constituting the lipophilic part of the surfactant generally has 1 to 1 carbon atoms from the viewpoint of surfactant action, but in the present invention, the surfactant lowers the surface tension. Since this is not necessary, compounds having carbon numbers outside the range of 71 to 71 and therefore having poor surface-active properties can also be used.

That is, the surfactant as used in the present invention includes homologues of cationic surfactants that have poor surfactant action.

A particularly preferred surfactant in the deposition solution of the present invention belongs to the cationic surfactants, and has the general formula RN (CH3)
, ・X (wherein, R is an alkyl group having t to 71 carbon atoms,
indicates CI or Br. ) is an alkyltrimethylammonium salt represented by This alkyltrimethylammonium salt has a wide concentration range in which it does not cause turbidity in the silica sol, has an extremely high deposition rate, and can instantaneously deposit silica and provide extremely excellent dropless properties.

As a method for implementing the present invention industrially and with high efficiency, a synthetic resin molded article (for example, a film or sheet) is continuously passed through and immersed in the deposition solution in a liquid tank containing the deposition solution. There are ways to process it. The residence time (immersion time) of the synthetic resin molded product in the depositing solution at t-t varies somewhat depending on the composition of the depositing solution and the type of resin, but is usually from several seconds to 70 seconds.
It is possible to achieve a sufficiently uniform deposition at a temperature of The deposition liquid of the present invention has a low surfactant concentration and a high surface tension, so even if you try to apply it using a roll coater method or brush coating method, the liquid will be repelled and there will be no color when sprayed. A spray method or a dipping method is used.

When using the immersion method, the synthetic resin molded product is immersed in an aqueous liquid and the non-droplet component is deposited on its surface, which is then pulled out.Therefore, there is little residual liquid component of the non-droplet agent, and therefore the surfactant is The residual amount of will be reduced.

When using the spray method, the remaining liquid components are removed using a squeeze roll or by applying vertical pressure to the treated film.

The synthetic resin molded article that has been immersed in the deposition solution according to the present invention is then normally dried using a hot air blast to form a product, which is desirable in terms of product handling and performance. It can withstand practical use even when it is dry.

Furthermore, depending on the concentration of the deposited liquid, an excessive amount of the deposited liquid may adhere to the synthetic resin molded article after the deposition liquid immersion treatment in the present invention, and the surface of the molded article after drying may become rough. To prevent this, the synthetic resin molded article after the immersion treatment may be subsequently passed through a water bath, rinsed with water to remove excess deposited liquid, and then dried. Even after rinsing with water, there is no change in the drip-free property, and in fact, as a result of washing away the excess qs1 surfactant, agricultural greenhouse 'JID
When K is used, it is possible to reduce the occurrence of mist inside the greenhouse, which is preferable.

The gelling agent used in this gelling agent treatment includes:
Any substance can be used as long as it has the effect of coagulating on the colloidal particles of silica sol. Generally, colloidal silica particles in silica sol have an i-negative charge on the surface,
The electric repulsion force between the charges prevents the particles from agglomerating and maintains a stable sol state. However, when a substance that neutralizes the charges is added to the sol, particles agglomerate. Gel. Examples of such gelling agents include acids, alkalis, salts, cationic surfactants, amphoteric surfactants, alumina sol, and organic substances such as methanol and a7tone. The gelling agent concentration in the gelling agent aqueous solution used for this purpose varies depending on the type of gelling agent, but is usually 0. / -10 weights ago, preferably /~j weights nine.

The synthetic resin molded products obtained by the manufacturing method of the present invention, such as synthetic resin films and sheets, do not become cloudy even during one winter when used for agricultural purposes, and exhibit excellent non-droplet properties. And the drip-free property lasts for a long period of 6 months or more. Despite its excellent drip-free properties, it is hardly observed that any liquid is generated inside or outside of the room at night. Furthermore, the film etc. has good transparency,
The surface is not sticky, and the strength of the silica coating is high both when dry and when wet, and the silica particles do not easily defrost even if the coating is rubbed by other substances in the phase.

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited in any way by these examples. Unless otherwise specified, the circles in these examples are based on the heavy standard.

Examples 7 to g Various treatment solutions (deposition solutions) shown in Table 7 were prepared by mixing diluted aqueous solutions of various commercially available silica sols and various aqueous solutions of commercially available cationic or amphoteric surfactants. My friend.

The 9 silica sol used was Nissan Chemical Co., Ltd.'s product name Snowtex aO5 in Examples/~3. The same Snowtex C1 Example 6, the same Snowtex C1 Example 7, the DuPont product name Ludox H8-(10, Example 1)
The product was Cataloid 8H-30 manufactured by Catalysts and Chemicals.

An agricultural low-density polyethylene film was immersed in each of the resulting deposition solutions for various times shown in Table 7, taken out, rinsed in water for 3 seconds, and then air-dried. The wet state of the film surface due to water when the film was removed from the water after rinsing, and the state of the film surface when the air-dried film was held over steam Kj seconds for 9 seconds were evaluated. The results were as shown in Table 7.

Comparative Example 1 ~ Tacholloidal iron hydroxide (Comparative example/), colloidal tin hydroxide (Comparative example 2), colloidal silica (Comparative example 3), colloidal alumina (Comparative gal), cationic surfactant (
Comparative examples include an aqueous liquid in which a relatively large amount of nonionic or anionic surfactant is added to colloidal silica or colloidal aluminum (Comparative Examples 6 to t), and a cationic surfactant added to silica sol in a relatively large amount. Aqueous liquid added in large quantities to (comparative example)
A polyethylene film similar to that used in Examples 7 to g was immersed using a steel machine, rinsed with water in the same manner, and then air-dried in the same manner.

In addition, in the preparation of colloidal iron hydroxide in Comparative Example / and colloidal tin hydroxide in Comparative Example λ, FeC1B・6H□0 and 8nC14・jH
, O, 8nC1e, and 2810 were dissolved in water, and the mixtures were subjected to pH adjustment and aging. Further, in all the comparative examples, the colloidal silica used was Snowtex jO (trade name, manufactured by Nissan Chemical Co., Ltd.), and the colloidal alumina used was Alinasol 200 (trade name, manufactured by Nissan Chemical Co., Ltd.).

Notes to Table 7 (1) Details of nine commercially available surfactants marked with Qin are as follows.

Hata l...Product name of cationic surfactant from Asahi Glass Co. -j11.2...Product name of amphoteric surfactant from NOF Corporationll113...Product name of amphoteric surfactant from Asahi Glass Co., Ltd. 1llll≠ ...Product name of Asahi Glass' anionic surfactant (,2)! The evaluation of water wettability after 7 baths is as follows.

0...Evenly wet.

Δ...It's wet, but it's partially brushed off.

×Keyaki... Completely squeezed and not wet.

(3) Test by steam after air drying) The evaluation was 9 as follows.

O...Transparent with some cloudy spots do not have.

Δ...Slightly cloudy.

X: Significantly cloudy.

As shown in Table/, the film of Example 1/~g was uniformly wetted with water after being rinsed with water and pulled up.
It showed that colloidal silica was deposited. front,
After air-drying, the film remained transparent and did not become cloudy even when exposed to steam. To obtain such a deposited film, the immersion time in the deposition solution was only 20 seconds, and in some cases even a few seconds was sufficient for the inside. It should be noted that in the films of Examples 7 to g, silica was deposited even after rinsing, and the surfactant content of the deposited layer after rinsing was extremely low, as evidenced by X-ray photoelectron spectroscopy (E8
CA) and confirmed by electron microscopy analysis.

On the other hand, the films obtained in Comparative Examples/and λ remained wet even after rinsing with water, so the film was exposed to steam after being air-dried in step 4, where the deposition of colloidal particles was introduced. The immersion time for the test case 4 is at least 73 minutes for Comparative Example / and at least 74 minutes for Comparative Example λ.
Nine in j minutes. As in Comparative Example 3, colloidal silica alone does not actually cause silica deposition, and as in Comparative Example D, colloidal arunna alone causes deposition.
Its deposition rate is extremely slow. Comparative example! ~The surface tension can be adjusted by using relatively large amounts of various surfactants as shown in ~l~
Item 4, which was reduced to 3 o dyne/mouth or less, is wet with water after immersion, whether colloidal particles are used or not, but when rinsed with water, both the surfactant and colloidal particles are completely removed. It was washed off by water and began to repel water, showing virtually no dripping properties. Furthermore, the treatment solution in which a relatively large amount of cationic surfactant was added together with colloidal silica as in Comparative Example had severe agglomeration, making it difficult to perform a stable coating treatment.

Example ri~l≠ Comparative example 70~no! As shown in Table 2, various synthetic resin films or sheets were similarly immersed using the same treatment liquid (deposition liquid, etc.) used in the above Examples and Comparative Examples, and rinsed in the same manner. A film or sheet obtained by air drying in the same manner was evaluated in the same manner.

The results were as shown in Table 2. That is, the film or sheet obtained in Example 1 ~/μ is 5.20
Even when immersed for less than a second, it exhibited excellent drip-free properties without causing any build-up due to steam. On the other hand, the films obtained in Comparative Examples 70 to /j required immersion for more than Kj minutes to avoid fogging due to steam, and were not practical.

Example/j-/1 Comparative Example/6~it As shown in Table 3, JL industrial low The dipping treatment was carried out by continuously passing through a density polyethylene film. The immersion time was about 20 seconds in each case. In Example/j, the film after immersion was continuously dried with hot air at the same temperature. In Example 1, the gold was continuously passed through the second tank filled with water for rinsing treatment, and then
It was continuously dried with tOC warm air. In Example 7, the diluted aqueous solution of alkali-based nazol was continuously passed through a round steel λ tank, and in Example 1, the water was continuously passed through a second tank containing water containing a cationic surfactant. , continuously dried with lOC warm air.

In addition, in Comparative Example 16 or /7, Comparative Example 6 or Comparative Example 1
Agricultural low-density polyethylene film was continuously passed through the first tank and soaked in the same treatment solution as used in the first tank, and then dried continuously with hot air. The immersion time was about 20 seconds in each case. In the case of Comparative Examples 16 and 17, there was uneven coating on the m glands even after dipping and drying only seven times, so dipping and drying were repeated twice. In addition, in Comparative Example/L, 0.00% norbitan oleate was added to the low-density polyethylene pellets as a non-droplet agent. j j 6 The material that had been kneaded 9 times was formed into a film by the inflation method.

Examples of the above/! Using each of the films obtained in ~/g and Comparative Example /l ~/l, an agricultural greenhouse was assembled in the winter (February), and the drip-free property, the sustainability of the drip-free property, etc. The occurrence of scratches on the sea bream and the occurrence of haze inside the house at night were measured by taking the sea bream. The results were as shown in Table 3.

In each of the films obtained in Examples /j to /g, silica was uniformly deposited on the film surface and exhibited excellent drop-free properties, even though the immersion time in the deposition liquid was extremely short. On the other hand, the films obtained in Comparative Examples /6 and /7 were repeatedly immersed and dried twice, but their drop-free properties and other performances were significantly inferior to those of Examples /j to /l. .

That is, the hazardous films obtained in Examples /j to /l did not generate fog and remained transparent immediately after being assembled in the house. There was also less haze. On the other hand, in the round can film obtained in Comparative Example 76~/l, cloudiness occurs due to adhesion of water droplets during the first 7 weeks, and during use, the water droplets gradually become larger and do not contact each other. It became transparent only after a continuous water film was formed. The occurrence of mist was also more significant than in Example/j-/l. Regarding the persistence of drip-free property, Examples/J to IT had the best durability, followed by Comparative Examples/7 and 16 in that order, and Comparative Example/I was the least satisfactory. In addition, when assembling the greenhouse, the film lining is rubbed or bent, so some of the film peels off and becomes scratched, and some parts of it become healthy. It was observed to some extent in Examples /j to /6 and Comparative Examples 16 and 77, but in No.1
It became almost unnoticeable while using the mouse. On the other hand,
In Examples 17 and /J', virtually no such scratches were observed. This indicates that the strength of the colloidal silica deposited film is significantly improved by post-treatment with a silica sol gelling agent such as an alkaline solution or a cationic surfactant-containing solution. .

Patent applicant: Mitsubishi Yuka Co., Ltd.

Claims (1)

[Scope of Claims] / Colloidal silica i-0,0j to -〇 weight circle, cationic surfactant and/or amphoteric surfactant /
/ A synthetic resin molded article is immersed in an aqueous liquid containing 0-4 to AO weight 9, or the aqueous liquid is sprayed to deposit colloidal silica particles on the surface of the synthetic resin molded article. Synthetic resin molded product with excellent drop properties The method according to claim 1g4, wherein the colloidal silica-containing aqueous liquid used for dipping the synthetic resin molded product has a surface tension cuff of 7 to 7j mains/cMI. 3. The cationic surfactant has the general formula RN” (CH
, ), *X- (wherein R represents an alkyl group having 1 to 1 carbon atoms, and X represents C1 or #iBr). #The method described in Section 1 or Section 2.