JPS59226037A - Resin composition for agricultural film - Google Patents

Abstract

PURPOSE:The titled resin composition having both improved transparency and heat retaining properties, obtained by blending a thermoplastic resin with a specific amount of magnesium hydroxide satisfying specific conditions such as BET specific surface area, etc., treated with a surface treatment, as an infrared absorber. CONSTITUTION:(A) 100pts.wt. thermoplastic resin e.g., PE, PP, PVC, etc.) is blended with (B) 1-20pts.wt. magnesium hydroxide having (i) 2-15m<2>/g, preferably 5-10m<2>/g BET specific surface area, (ii) 0.3-2.0mu, preferably 0.5-1.5mu size of single crystal by electron microscopy, and (iii) >=90wt%, preferably >=95 wt% secondary particles having <=2mu particle diameter, treated with (iv) a surface treatment (sodium polyoxyethylene lauryl ether sulfate, etc.), to give the desired composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a resin composition used for agricultural films having excellent transparency and heat retention.

Agricultural films used in greenhouse cultivation, tunnel cultivation, etc. of agricultural products are required to have excellent weather resistance, aging resistance, etc., as well as both transparency and heat retention.

This is because it is a necessary characteristic for an efficient greenhouse film that sunlight passes through the film at the highest possible transmittance during the day, while at night the temperature rises due to daytime sunlight irradiation. This is because it is necessary to maintain the temperature inside the greenhouse. However, the heat retention of the lever is achieved by making the film efficiently absorb infrared rays emitted from the ground surface and plants at night (VC). By the way, the thermoplastic resin itself, which is the raw material for the film, does not exhibit an efficient infrared absorption function, so in order to prevent the heat absorbed by the plants inside the greenhouse during the day from escaping outside the greenhouse at night, it is necessary to absorb the heat absorbed by the plants into the film. It is necessary to add a substance that absorbs infrared rays well.

[Prior art]

It has already been proposed that magnesium hydroxide is suitable as such an efficient infrared absorber (Japanese Patent Publication No. 5
No. 7-34871, JP-A-55-164238). However, magnesium hydroxide has a small crystal particle size and strong cohesiveness, so it tends to form coarse secondary particles (
The average secondary particle diameter is 10 to 100μ). Therefore, even if treated with surface treatment agents such as fatty acids, polyhydric alcohols, paraffin, and silane coupling agents, the size of the particles dispersed in the resin will be at most 10 to 100μ, and If a resin composition containing this is used to form a film, because it re-agglomerates to form larger secondary particles, or the attached moisture contained in the secondary particles evaporates at the processing temperature, Fisheye Kinjitari,
A visible amount of poorly dispersed magnesium hydroxide is present, which inevitably deteriorates the transparency of the film. This results in poor translucency as an agricultural film, as well as poor mechanical properties such as tensile strength, making it impractical.

[Object and structure of the invention]

As a result of intensive research to overcome all of the drawbacks of the conventional magnesium hydroxide, the inventors of the present invention have found a solution to the problem by using a special magnesium hydroxide that satisfies the following conditions as an infrared absorbing agent. It is something that That is, in the present invention, 100 parts by weight of a thermoplastic resin with a specific surface area of 2 to 15 Hfy, preferably 5 to 107/1, +++) is added using a microscope at a magnification of 10,000 times. The average size of single crystals (plate crystals) measured from photographs taken with 0.3 to 2.0μ, preferably 0.5 to i,s
μ, (+iil In the particle size distribution of the secondary particle diameter measured by the Luzetx method, 90% or more are 2 μ or less, preferably 9
5% or more, and 4. A resin composition for agricultural film containing 1 to 20 parts by weight of magnesium hydroxide in the claw part treated with a surface treatment agent, such a composition The film formed using A as a raw material has no fish eyes, no visually visible coarse particles with poor dispersion, has excellent transparency and heat retention, and has good mechanical properties. It meets the requirements of a commercial film.

In order to produce a film with high transparency, which is the objective of the present invention, it is necessary to satisfy all of the above four conditions, and if even one of these conditions is not met, the objective highly transparent film will not be obtained. It is not possible.

That is, the magnesium hydroxide used in the present invention must have (1) a BET specific surface area of 2 to 15, and if it is less than 2111/y, the aggregation is strong and 2
Either the secondary particles are too large or the single crystal is larger than 2μ, and in either case the transparency deteriorates and the reverse vc, 1
If it exceeds 5 nc/y-gold, the size of the single crystal becomes too small and the agglomeration is strong, resulting in coarse secondary particles.

Single crystal size determined by electron microscopy is 0.3-2.0
It is necessary that μ.

The average size of single crystals (plate-like crystals rzto) is measured by a photograph taken at a magnification of 0.00 times, but if this size is smaller than 0.3μ, the aggregation will be strong and the secondary particles will be large and the film will be damaged. The transparency of the film deteriorates, and conversely, if it becomes too large than 2μ, the transparency of the film deteriorates.

(Iitl It is necessary that 90% or more of the secondary particle size is 2 μ or less. This measurement is performed using the Luzex method, but if the secondary particle size is less than 90 cm, the secondary particle size is less than 90 cm. becomes too large, deteriorating the transparency of the film.

In the above, the relationship between each condition is that BffiT is 2 to
Even within the range of i s m/y, if the aggregation is strong, the single crystal often has a diameter of 0.3 μ or less. For example, if a single crystal is 0.
Even if the particle size is 3μ, if the aggregation is strong, it will be about 2 to 5 times lower than BfCT, but in the particle size distribution of Luzex, the secondary particle size
The value below μ may be less than 80 inches.

Cφ surface treatment is approximately 1 to 1 for magnesium hydroxide.
0% by weight of a surface treatment agent (examples given below).

〔Measuring method〕

(a) BIT specific surface area is measured by liquid nitrogen adsorption method.

(2) To determine the size of a single crystal, take an electron micrograph at a magnification of 10,000 times, measure 10 sizes, and define the average value as the size of the single crystal.

(c) To determine the particle size distribution using the Rouzetx method, take a sample of approximately 5 cm on a glass plate, add the dispersant "Dislight" (trade name), mix well with a spatula, disperse, and then dilute by adding chlorobenzene solution. Then, place one drop on a slide Dallas, place a cover glass on top of it, and put it under an optical microscope at a magnification of 400 times, and then transfer it to a cathode ray tube and count the size of all the particles.

[Manufacturing example]

The magnesium hydroxide used in the present invention is
Manufactured by the method disclosed in No. 15799. Its outline is the following formula% formula% However, in the formula, A (Gal or No, X is 0<X<
0.2, m is 0 to 6, and the basic chloride or basic magnesium nitrate represented by the following is added in an aqueous medium under pressurized conditions, for example, 1.
Magnesium hydroxide is synthesized by heating to a temperature of about 20 to 250°C, washed with water, and then treated with a surface treatment agent of about 1 to 10% by weight based on the weight of magnesium hydroxide. It will be done.

Specific examples of surface treatment agents include alkali gold maple salts of higher fatty acids, polyoxyethylene lauryl ether sulfate sodium salts, esters of glycerin and higher fatty acids, 7
Examples include run type coupling agents and titanate coupling agents.

The surface treatment is carried out by adding water and an alcohol solution of the above-mentioned surface treatment agent to magnesium hydroxide suspended in water or in a powdered state, and stirring the mixture optically.

[Thermal 0T plastic resin] The agricultural film composition of the present invention has a thermoplastic resin of 10
It can be obtained by blending about 1 to 10 parts by weight of magnesium hydroxide per 0 parts by weight of the above specified r.

If the amount of magnesium hydroxide is less than 1 part by weight, the infrared absorbing effect will not be sufficient, and if it exceeds 20 parts by weight, the transparency will be adversely affected, which is not preferable.

Examples of the thermoplastic resin used in the present invention include low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, polyvinyl chloride, and ethylene-vinyl acetate copolymer.

In the present invention, the infrared absorbing agent other than magnesium hydroxide may be a known infrared absorbing agent such as silicon oxide fine powder.

[Film production]

The production of the film can be carried out, for example, by using the total antioxidant composition of the present invention,
It is mixed with other additives such as stabilizers, ultraviolet absorbers, and lubricants, and then kneaded in a melt mixing device such as a roll, a kneader, and an extruder.
It can be molded into a film using a known molding method such as calendar molding.

[Examples and effects]

Next, the present invention will be specifically explained with reference to Examples.

Example I BIiiiT specific surface area 9 μm, single crystal size 0.8μ,
Magnesium hydroxide powder 500 P'kl O,e (DIlin water (approximately 70
While stirring, add 500ml of warm water (approximately 70°C) in which oleic acid Noda 107 corresponding to 2 ts per weight of magnesium hydroxide is dissolved, and after stirring for approximately 30 minutes, 1 filtration, dehydration, Dried and crushed.

Add 10 parts of the magnesium hydroxide obtained in the above manner to the parts of low-density polyethylene (IOO), mix the parts using an extruder to make Benz) (2 parts), and use this pellet to perform inflation molding. A gold film with a thickness of 50 μm was formed using the method.The entire circumference of this film was used to construct an agricultural tunnel, and the transmittance of visible light (wavelength 0.4 to 0.7 μm) and heat retention effect of the film were investigated.

Comparative Example 1 BKT specific surface area s 87Q/P, single crystal size 0.
Magnesium hydroxide having a secondary particle size of 0.06 μm and 72 μm or less was subjected to surface treatment in the same manner as in Example 1, and then a film was formed in the same manner as in Example 1.

Comparative example 2 A film was prepared by surface treatment and film formation in the same manner as in 1.

Comparative Example 3 BET specific surface area 21 lrt/y-1 Magnesium hydroxide with a single crystal size of 0.2μ and secondary particles of 2μ or less of 94cm was surface-treated and formed into a film in the same manner as in Example 1. made.

Comparative Examples 4 and 5 In Example 1, the combination of magnesium hydroxide was
The treatment was carried out in the same manner as in Example 1, except that the weight was changed to 0.5 parts (Comparative Example 4) and 0.5 parts (Comparative Example 5).

Comparative Example 1 Using the low density polyethylene of Example 1, a film with a thickness of 50 μm was made by an inflation method.

Example 1 was also applied to the films of Comparative Examples 1 to 5 and Control Example 1.
The same measurements were carried out. The results are shown in Table 1.

Table 1 Visible light transmittance and heat retention effect of each film Example 2 Magnesium hydroxide powder 50 with BET specific surface area 14, single crystal size 1.4μ, secondary particle size of 2μ or less 98cm
．． 0 fF is suspended in warm water (about 80 °C) at about 51 °C,
While stirring, 500 ml of warm water (approximately 80"C) in which 2Of sodium stearate had been dissolved was added, and stirring was continued for approximately 30 minutes. After that, filtration, dehydration, drying, and pulverized magnesium hydroxide, polyvinyl chloride, and Mix with the following recipe, cross-mix it in an extruder, and then use the inflation method to create a thickness of loo.
I made a μ film. Example 1 about this film
Visible light transmittance and heat retention were measured using the same method.

Prescription Polyvinyl chloride 60 loo DO
P 30 #Stabilizer lN Epoxy plasticizer 2 Hydroxide Madafusiwam 6 # (10) Comparative example 6
and 7 In Example 2, the formulation FA of magnesium hydroxide?
r, 3 (1 tonne part (Comparative Example 6), 0.5 fi part (
The process was carried out in the same manner as in Example 2 except that Comparative Example 7) was used.

Control example 2 Implementation t+! In the formulation of 12, film gold was prepared without incorporating magnesium hydroxide.

The above results are shown in Table 2.

Claims (1)

[Claims] To 100 parts by weight of thermoplastic resin, tiJ BET ratio: &ml (2 to 15 m' de (1
1)1! Single crystal size by L-son microscopy is 0.3~
2, 0μ fija The secondary particle diameter is 2μ or less and is 9o or more, t
Vl An agricultural film resin composition treated with a surface treatment agent and containing 1 to 20 parts by weight of magnesium hydroxide.