JPH1058417A - Release sheet for concrete from - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid sticking of limewask when concrete is applied and to decrease manhour for polishing of a form and manhour for applying a releasing agent by incorporating a specified pts.wt. of a water repellent polymer selected from a group consisting of fluoroesins and silicone resins. SOLUTION: A water repellent polymer consists of a fluororesin or a silicone resin. When the amt, of compounding of this water repellent polymer is less than 0.1 pt.wt. to 100 pts.wt. pololefin resin, mold releasing effect of a release paper obtd. for a concrete from to concrete is low and when it exceeds 50 pts.wt., especially in the case of a silicone resin, water repellency is good but as affinity with calcium silicate being a main ingredient of cement is increased and on the contrary, releasing properties are decreased, it is restricted to 0.1-50 pts.wt, pref. 3-10 pts.wt. to 100 pts.wt.polyolefin resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a release sheet for a concrete formwork.

[0002]

2. Description of the Related Art Conventionally, concrete products or structures are made of a wooden form made of plywood or particle board, a metal form made of ordinary steel or galvanized steel, or a plastic molded form. Has been used. The above-mentioned wooden formwork takes advantage of inexpensiveness and the like, and is usually used by applying a release agent or a paint of a urethane type, an acrylic type, an epoxy type or the like to the surface, but the obtained concrete product or It has the drawbacks that the dimensional stability of the structure is poor and that the mold itself is inferior in durability.

[0003] On the other hand, metal molds are more expensive than wooden molds, but have the advantages of excellent dimensional stability, durability, and a remarkable increase in the number of reuses. However, metal molds have poor releasability like wooden molds,
Since the finished surface of the resulting concrete product or structure is deteriorated, there is a problem that the mold surface is polished each time after demolding at the time of re-use, and a mold release agent must be frequently applied. Had to be troublesome.

[0004] Plastic molds have the advantage that they have good releasability from concrete and the surface finish of the resulting concrete product or structure is beautiful, but they have the disadvantage of poor durability. Have.

[0005] As described above, none of the molds satisfies both the releasability and the durability for concrete, and the molds which require less releasability management at work sites and less work for selecting defective molds. A frame is required. As an attempt for improvement, Japanese Patent Publication No. 58-22334 proposes a plastic molding form using medium-low pressure polyethylene or polypropylene, and Japanese Patent Publication No. 3-22805 discloses an unsaturated carboxylic acid or a derivative thereof. A proposal has been made to improve the releasability of concrete by laminating a resin composition comprising a modified polyolefin resin, an unmodified polyolefin resin and an unsaturated carboxylic acid or a derivative thereof on the surface of a metallic formwork.

The concrete molds disclosed in Japanese Patent Publication No. 58-22334 and Japanese Patent Publication No. 3-22805 each have improved the releasability to concrete to some extent. At the time of placing a concrete foundation, if ready-mixed concrete (hereinafter abbreviated as ready-mixed concrete) is poured from a concrete mixer truck between the assembled concrete forms, the ready-mixed concrete will jump up and adhere to the surface of the formwork as a so-called "slag". Inevitably, the hardened slag gradually contaminates the polyolefin resin film on the surface of the formwork, and sometimes the hardened slag may peel off from the surface of the formwork, resulting in a finish on the surface of the concrete product or structure. If it is used continuously in this state, the releasability rapidly deteriorates.

[0007] The present inventors have intensively studied the adhesiveness of ready-mixed concrete to polyolefin resin, and have found that the adhesiveness of ready-mixed concrete to polyolefin resin has a strong correlation with affinity for water. It has been reached.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned facts, and has as its object to reduce the man-hours required for polishing a formwork without sticking during concrete casting. Another object of the present invention is to provide a release sheet for concrete formwork which is excellent in releasability and can reduce the number of steps of applying a release agent.

[0009]

The present invention relates to a concrete comprising 100 parts by weight of a polyolefin resin and 0.1 to 50 parts by weight of at least one water-repellent polymer selected from the group consisting of fluororesins and silicone resins. The gist is a release sheet for a formwork.

In the present invention, the polyolefin resin is
There is no particular limitation, and low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, polybutene-1, poly (4-methylpentene-1)
In addition, copolymers containing other olefin-based monomers such as ethylene and propylene as main components and copolymerizable with other α-olefins and other monomers (for example, ethylene-propylene copolymer, ethylene-butene- 1 copolymer, ethylene-hexene-1 copolymer, ethylene-4-
Methylpentene-1 copolymer, ethylene-octene-1
Copolymers). These polyolefin resins may be used alone, or two or more kinds may be used in combination.

The fluororesin is made of a polymer containing a fluorine atom in a molecule, and includes a fluororubber. Examples of the fluororesin include, for example, an ethylene tetrafluoride resin (PTFE), an ethylene tetrafluoride-perfluoroalkoxyethylene copolymer resin (PFA), an ethylene tetrafluoride-propylene hexafluoropropylene copolymer resin (FEP), Examples thereof include a fluorinated ethylene-ethylene copolymer resin (ETFE), an ethylene trifluoride chloride resin (CTFE), a vinylidene fluoride resin (PVDE), and polyvinyl fluoride (PVF). These may be used alone or in combination of two or more.

The silicone resin is composed of an organopolysiloxane having a siloxane bond as a skeleton, and includes silicone oil, silicone resin, and silicone rubber. Examples of the silicone resin include dimethyl silicone oil, methylphenyl silicone oil, methyl hydrogen silicone oil, cyclic polydimethylsiloxane, alkyl-modified silicone oil, amino-modified silicone oil, silicone-polyether copolymer, and fatty acid-modified silicone oil. Silicone oils such as epoxy-modified silicone oil and fluorosilicone oil, pure silicone resin, alkyd-modified silicone resin, polyester-modified silicone resin, epoxy-modified silicone resin, acrylic-modified silicone resin, urethane-modified silicone resin, and other silicone resins, and millable silicone rubber , Deacetic acid type silicone rubber, oxime resistant silicone rubber, dealcohol type silicone rubber,
Examples include deacetone type silicone rubber, deaminoxy type silicone rubber (one-part type), condensation type silicone rubber, and addition type silicone rubber (two-part type). The above silicone resins may be used alone or in combination of two or more.

The water-repellent polymer used in the present invention comprises the above-mentioned fluororesin or silicone resin.
If the amount is less than 0.1 part by weight, the releasing effect on the concrete of the obtained release sheet for concrete form is low, and if it exceeds 50 parts by weight, especially in the case of silicone resin, the water repellency is good. However, the affinity for calcium silicate, which is the main component of cement, increases, and the releasability decreases. Therefore, the amount is limited to 0.1 to 50 parts by weight, preferably 3 to 100 parts by weight of the polyolefin resin. ~ 1
0 parts by weight.

The release sheet for concrete formwork of the present invention is not particularly limited in its forming method. For example, a polyolefin resin and a water-repellent polymer may be added to an ultraviolet absorber, a heat stabilizer, Inhibitors, lubricants,
A resin composition to which a coloring agent or the like has been added is formed into a sheet by melt extrusion using a T-die method or an inflation method, and then a metal mold, a wooden mold, a plastic mold, or the like is formed by welding or using an adhesive. Alternatively, it may be formed by pulverizing the above resin composition and directly laminating it on the above-described mold or the like by an electrostatic coating method, a fluid immersion method, a powder spraying method, or the like.

The release sheet for concrete formwork of the present invention may be used as a single-layer sheet, but it may be laminated with a reinforcing sheet such as a vertically orthogonal laminated nonwoven fabric or a net or a cushioning sheet such as a plastic foam. May be used.
Examples of the method of bonding and fixing to a concrete form include a fixing method using an adhesive, an adhesive, heat fusion, staples, nails and the like.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

Example 1 Polypropylene (manufactured by Tokuyama Co., Ltd.)
100 parts by weight of trade name "RB110" and ethylene tetrafluoride resin (manufactured by Daikin Industries, trade name "LeBlanc L-
5)) After mixing 3 parts by weight in advance, a release sheet for concrete formwork having a thickness of 100 μm was prepared by T-die extrusion molding at a molding temperature of 280 ° C.

Example 2 The procedure of Example 1 was repeated, except that 3 parts by weight of an epoxy-modified silicone oil (trade name "KF102", manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of 3 parts by weight of the ethylene tetrafluoride resin. 100 μm in thickness in the same manner as in Example 1.
m was prepared.

Example 3 A block copolymer comprising a fluoroalkyl group-containing polymer segment and an acrylic polymer segment (manufactured by NOF Corporation, instead of 3 parts by weight of the tetrafluoroethylene resin of Example 1) Product name "MODIPA F50
0 ") A release sheet for concrete formwork having a thickness of 100 µm was prepared in the same manner as in Example 1 except that 3 parts by weight was used.

(Example 4) A block copolymer comprising a siloxane group-containing polymer segment and an acrylic polymer segment (trade name, manufactured by NOF Corporation, instead of 3 parts by weight of the tetrafluoroethylene resin of Example 1) "Modiper FS70
0 ") A release sheet for concrete formwork having a thickness of 100 µm was prepared in the same manner as in Example 1 except that 3 parts by weight was used.

Comparative Example 1 A release sheet for a concrete form having a thickness of 100 μm was prepared in the same manner as in Example 1 except that the ethylene tetrafluoride resin of Example 1 was not added.

(Comparative Example 2) 15 parts by weight of a modified polyolefin obtained by heating and kneading 100 parts by weight of high-density polyethylene (manufactured by Mitsubishi Chemical Corporation, trade name "LY20") and 0.2 part by weight of maleic anhydride in an extruder And 85 parts by weight of high-density polyethylene (manufactured by Mitsubishi Chemical Corporation, trade name "LY20") in Example 1
In the same manner as in the above, a release sheet for a concrete formwork having a thickness of 100 μm was produced.

In order to evaluate the performance of the release sheets for concrete forms obtained in the above Examples and Comparative Examples, the contact angles,
The slippage of ready-mixed concrete and the releasability of concrete were tested by the following methods. The results are shown in Table 1.

1. Contact angle: Distilled water was dropped on the surface of the obtained release sheet for a concrete form using a contact angle measuring device (trade name "Elmagoniometer", manufactured by Elma Corporation), and the contact angle between the two was measured. .

2. Sliding property of ready-mixed concrete: Draw a circle of 3 inches φ on the surface of the obtained release sheet for concrete form, place 100 g of ready-mixed concrete in the circle, and then slowly and vertically release the release sheet for concrete form. Stand up and drop the ready-mixed concrete. After the ready-mixed concrete falls, the release sheet for concrete formwork is weighed, and the amount of the ready-mixed concrete remaining in the circle is calculated.
The smoothness of the ready-mixed concrete was evaluated in three stages: 0 g, x: over 40 g.

3. Releasability of concrete: width 160m
m, 600 mm in height, 1000 mm in length, using a peeling sheet for concrete form used 10 times each at a residential foundation setting site, cast a ready-mixed concrete, and after curing, actually release the form ：: The form was easily peeled off, and the obtained concrete foundation surface was clean, and の: the form Although it is easy to peel off, there are slight scratches on the obtained concrete foundation surface,
×: The form was hardly peeled off and the obtained concrete foundation surface was poor, and evaluated in three stages.

[0027]

[Table 1]

[0028]

The release sheet for concrete formwork of the present invention is constructed as described above, so there is no sticking at the time of placing concrete, thus reducing the number of steps for polishing the formwork and reducing the number of steps for applying the release agent. The mold is extremely excellent in mold releasability, and the number of times of use or the period can be extended together with the concrete form.

Claims (1)

[Claims] 1. A polyolefin-based resin having 100 parts by weight,
A release sheet for concrete formwork, comprising 0.1 to 50 parts by weight of at least one water-repellent polymer selected from the group consisting of a fluororesin and a silicone resin.