JPH0819625B2 - Adhesive for carpet backing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides an adhesive for backing used in the production of tufted carpets, needle punched carpets, tile carpets, artificial turf, and the like.

[Conventional technology]

Conventionally, natural rubber latex and various synthetic rubber latex have been used as adhesives for carpet backing.

Recently, the manufacturing conditions for carpets using adhesives have become more stringent due to the rationalization of manufacturing, and the usage conditions have become more stringent as their applications have expanded, resulting in even better adhesive strength and heat aging resistance than ever before. Is required.

Conventionally, an adhesive for carpet backing is a copolymer latex containing a filler and optionally a dispersant, an antioxidant (styrenated phenol, 2,6-ditertiary-4).
-Methylphenol, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), etc.), defoaming agent, foaming agent, Add a cross-linking agent,
Further, it is produced by adjusting the viscosity to an appropriate level with a thickener.

Such a carpet backing adhesive is applied to all carpets to be backed such as tufted carpet, needle punched carpet, knitted carpet, tile carpet or hook carpet.
Further, as the backing method at that time, for example, in the case of tufted carpet, a carpet is provided on the back surface of a raw fabric obtained by tufting tufted yarns such as nylon crimped yarn and polyester crimped yarn on a primary base fabric made of polypropylene or the like. By applying a backing composition and hot-air drying as it is, or by applying a hot air-drying after applying a secondary base fabric such as jute woven fabric, synthetic fiber nonwoven fabric after applying the composition,
Manufactured. In recent years, in order to improve productivity in the carpet manufacturing process, a method has been adopted in which after applying an adhesive to a carpet raw material, a large-sized dryer is used to quickly dry the carpet under conditions of high temperature and high air flow. Also, the demand for electric heating carpets is increasing. For this reason, the adhesive for carpet backing is important not only in adhesiveness but also in heat aging resistance during the production and use of the carpet.

[Problems to be solved by the invention]

Although the adhesive for carpet backing seems to be an already completed product with various improvements, recently,
It has become noticeable that the adhesive-backed carpet is stored in a warehouse, displayed for sale at a store, or laid on the floor and turned yellow during use. Yellowing was particularly noticeable during storage in a warehouse where forklifts are used and when used on the floor inside an oil stove.

The inventors of the present invention have conducted extensive studies on what is necessary for the adhesive for carpet backing, such as adhesive strength, heat aging resistance, and texture, and the adhesive backed on the carpet does not yellow. Arrived

The main object of the present invention is to provide an adhesive for carpet backing which is excellent in yellowing resistance. As a result of various studies on the cause of yellowing of the adhesive, yellowing was found in the atmospheric NO
It was found to be correlated with ₂ gases. Therefore, the present invention has succeeded in solving the problem by evaluating the adhesive by the gas yellowing resistance test described below. That is, the present invention is obtained by emulsion polymerization of 20 to 70% by weight of an aliphatic conjugated diene, 0.5 to 8% by weight of an ethylenically unsaturated carboxylic acid, and 22 to 79.5% by weight of another monomer copolymerizable therewith. Phenol-based antioxidant having a substituent having an ethylenic double bond and having a substituent at both ortho-positions and para-positions relative to the phenolic hydroxyl group per 100 parts by weight of the copolymerized latex (solid content) 0.02 The present invention provides an adhesive for carpet backing, characterized in that it contains from 6 to 6 parts by weight and from 0 to 750 parts by weight of a filler.

Examples of the aliphatic conjugated diene used in the copolymer latex of the present invention include 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene and 2-cyano-1,3-
Butadiene and the like can be mentioned, but 1,3-butadiene is preferable. These aliphatic conjugated dienes can be used alone or in combination of two or more.

The aliphatic conjugated diene is an essential component for imparting appropriate flexibility and strength to the obtained adhesive for carpet backing, and the proportion thereof is 20 to 70% by weight, preferably 25 to 65%.
% By weight, and below 20% by weight flexibility as described above,
The adhesive strength is inferior. On the other hand, if it exceeds 70% by weight, it becomes too soft and the strength becomes low, and the most important physical property, heat aging resistance, deteriorates.

Examples of the ethylenically unsaturated carboxylic acid in the present invention include monocarboxylic acids such as acrylic acid and methacrylic acid, fumaric acid, maleic acid, dicarboxylic acids such as itaconic acid, and of these, the use of dicarboxylic acids Among them, itaconic acid is particularly preferably used. These ethylenically unsaturated carboxylic acids may be used alone or in combination of two or more.

The amount of the ethylenically unsaturated carboxylic acid used is 0.5 to 8% by weight, preferably 0.7 to 7% by weight. If it is less than 0.5% by weight, the stability of the latex at the time of polymerization is poor and coagulation easily occurs, and the obtained product is obtained. Latex has poor mechanical and chemical stability. Further, the resulting adhesive for carpet backing is not preferable because it shows a change with time, and further the heat aging resistance is deteriorated. On the other hand, if it exceeds 8% by weight, the latex obtained has a high viscosity and is not practical.

Other copolymerizable monomers in the present invention include aromatic vinyl compounds, alkyl (meth) acrylates, vinyl cyanide compounds, vinyl acetate and acrylamide.

Among them, examples of the aromatic vinyl compound include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, and chlorostyrene, and styrene is particularly preferable.

Moreover, as alkyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl (meth) acrylate, propyl (meth) acrylate, octyl ( Meta)
Examples thereof include acrylate, benzyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and hydroxyethyl (meth) acrylate. Of these, methylmethacrylate is particularly preferable.

Further, examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile, and among them, acrylonitrile is preferable.

These other monomers may be used alone or in combination of two or more.

In particular, when methyl methacrylate is used as the other monomer for copolymerization, the polymerization stability is remarkably improved, and therefore it is preferably applied.

The amount of these other monomers used is 22 to 79.5% by weight, preferably 25 to 75% by weight.
When the ratio of the aliphatic conjugated diene used is large and the obtained copolymer latex is used, the carpet feel is too soft, which is not preferable. On the other hand, when it exceeds 79.5% by weight, it becomes too hard on the contrary and is handled. There is an obstacle on the top,
The adhesive strength is poor. For example, the main physical properties of carpet,
The yarn removal strength and the peeling strength from the secondary base cloth are inferior.

As a polymerization method for obtaining the latex of the present invention,
Emulsion polymerization methods commonly used, i.e., batch, semi-continuous,
It can be adopted in any method such as a continuous polymerization method, a seed polymerization method and a power feed polymerization method. Polymerization uses an emulsifier, a chain transfer agent, a polymerization initiator, an electrolyte, a reducing agent, a pH adjusting agent, etc., and a polymerization temperature of 5 to 90 ° C, preferably 30 to 70 ° C, a polymerization time of 5 to 30 hours, and a polymerization conversion rate. About 98%
This is done.

The phenolic antioxidant used in the present invention is characterized by having a substituent having an ethylenic double bond, and having a substituent at both ortho and para positions with respect to the phenolic hydroxyl group. is there. Specifically, the following compounds (1) to (4) are listed.

Here, R ₁ and R ₂ are the same or different alkyl groups having 1 to 3 carbon atoms, R ₃ and R ₄ are the same or different alkyl groups having 1 to 5 carbon atoms, and especially R ₁ and R ₂ are CH ₃ , R ₃ and R ₄ are (CH ₃ ) ₃ C
-(2-tert-butyl-6 (3'-tert-butyl-5'-methyl-2'-hydroxybenzyldiyl) -4-methylphenyl acrylate) Of these, the compound (1) is particularly preferable. The amount of the phenolic antioxidant used is 0.02 to 6 parts by weight, preferably 100 parts by weight (solid content) of the copolymer latex.
It is 0.05 to 5.5 parts by weight, and if it is less than 0.02 parts by weight, the desired sufficient gas yellowing resistance and heat aging resistance cannot be obtained, while 6
Even if used in excess of parts by weight, the effect does not increase proportionally, which is uneconomical. Other antioxidants include organic sulfur compounds such as distearyl 3,3'thiodipropionate, carbamate compounds such as zinc diethyldithiocarbamate, and zinc oxide, which may be used in combination. The phenolic antioxidant in the present invention has only to be contained in the finally obtained adhesive for carpet backing, and its addition timing is not limited.

The present invention is a carpet backing adhesive containing a copolymer latex and a specific antioxidant as described above, but may further contain a filler if necessary.

Examples of the filler include calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, barium sulfate, silicic acid, silicate, titanium oxide, magnesium carbonate, and inorganic fillers such as calcium carbonate.
It is not limited to these. The filler may be used alone or in combination of two or more.

The proportion of the filler used is the above-mentioned copolymer latex.
0 to 750 parts by weight of filler with respect to 100 parts by weight (solid content),
It is preferably about 100 to 500 parts by weight. Blending with a small amount of filler is disadvantageous in terms of cost, but there is no particular problem in terms of physical properties. On the other hand, if it exceeds 750 parts by weight, the heat aging resistance of the obtained composition deteriorates, which is not preferable.

Further, the composition viscosity of the composition of the present invention is usually 20,000 to 40,0, for example, in the proportion of the backing of carpet.
00 cps, preferably 25,000 to 35,000 cps, and its solid content concentration is usually 65 to 80% by weight, preferably 70 to 78% by weight.
Is adjusted using a thickener or water. That is, if the viscosity of the composition is less than 20,000 cps, the permeability to the carpet becomes large and the peel strength becomes weak, while if it exceeds 40,000 cps, the coatability becomes poor and unevenness occurs. Further, if the solid content concentration of the composition is less than 65% by weight, the water content is too much and the drying efficiency is poor, and as a result, the yarn removal strength and peeling strength may be reduced, while if it exceeds 80% by weight, the composition viscosity will be low. As a result, the coating efficiency rises and coating efficiency deteriorates, or coating unevenness occurs, resulting in variations in quality such as peel strength and feel.

As described above, the adhesive for carpet backing of the present invention contains a copolymer latex and an antioxidant, and further contains a filler as a main component, if necessary, and further contains a dispersant, a defoaming agent, A crosslinking agent, a thickener, a foaming agent, a colorant, a flame retardant, a preservative, an antiaging agent, a stabilizer, a vulcanization accelerator, an antistatic agent, a pH adjuster and the like can be added.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples. The parts and% in the examples are by weight unless otherwise specified.

Further, in the examples, the heat aging test and the gas yellowing test were carried out by the following methods.

a. Heat aging test Carpet backing adhesive with a film thickness of 1 m after drying
A film made of an adhesive for carpet backing was obtained by coating on a polyester sheet so as to have m, naturally drying at 25 ° C. for 2 days, and then peeling off from the polyester sheet. Was exposed in a gear oven at 150 ° C. for 10 hours, and the discoloration, flexibility and hardness of the film were evaluated. Hardness is spring type JI
Measured using an S hardness tester, those with significant discoloration and those with a large hardness (large numerical value) were judged to have poor heat aging resistance, and the softness was evaluated as soft or medium soft by the touch of the film. The hardness was evaluated in 3 grades.

b. Gas yellowing resistance test A film made of the adhesive for carpet backing obtained by the above method was applied with NO ₂ (fluorine dioxide) gas 2 (volume).
% Discoloration of the film after standing at 20 ° C. for 120 minutes in an atmosphere was judged. Those with a marked degree of discoloration have poor gas yellowing resistance.

Examples 1 to 3 and Comparative Examples 1 to 10 Preparation of Copolymer Latex 100 parts of monomer, 2.0 parts of sodium dodecylbenzenesulfonate, 0.2 part of t-dodecyl mercaptan, ethylenediamine with the monomer charging composition shown in Table 1. 0.01 parts of sodium tetraacetate, 0.8 parts of sodium persulfate and 200 parts of water were charged into a stainless reactor having an internal volume of 100, and the polymerization temperature was 40%.
Polymerization was continued by stirring at -60 ° C for 20 hours to obtain copolymer latexes A to G.

The polymerization was a batch charging method, the polymerization conversion rate of the obtained latex was 99.5% or more, the polymerization stability was good except for the latexes F and G, and there was almost no coagulated product.

After the polymerization is completed, adjust the pH and adjust with potassium hydroxide.
Was adjusted to 8.0.

Preparation of Adhesive for Carpet Backing Next, the copolymer latex A thus obtained
The antioxidant of the present invention was added to G to obtain a carpet backing adhesive with the following formulation, and the heat aging resistance test was conducted using this adhesive. The results are shown in Table 2. Formulation (part) Copolymer latex 100 Potassium pyrophosphate 0.8 Calcium carbonate Variable thickener (sodium polyacrylate) 1.0 The adhesive for carpet backing is prepared by adding a dispersant to a copolymer latex containing an antioxidant. After adding potassium pyrophosphate etc., which is a filler, a certain heavy calcium carbonate is added, and after sufficiently dispersed, the solid content concentration is 75%,
Viscosity about 30,000cps (Brookfield viscometer, BM type N
It was adjusted with a thickener and water so that it was measured at 6 rpm using o.4).

As is clear from Tables 1 and 2, Examples 1 to 3 are cases in which the copolymer latex and the antioxidant used in the present invention were used, and all were changed within the scope of the present invention. And the gas yellowing resistance and heat aging resistance are good.

In Comparative Example 1, the use amount of the antioxidant of the present invention is less than the range, in Comparative Examples 2, 3, 4, 9 and 10, the type of antioxidant is out of the range, and in Comparative Examples 5 to 6, the amount of butadiene is It is outside the scope of the present invention, and in Comparative Examples 7 to 8, the ethylenically unsaturated carboxylic acid is outside the scope of the present invention. In these comparative examples, gas yellowing resistance and heat aging resistance were poor.

〔The invention's effect〕

The carpet backing adhesive of the present invention is a carboxy-modified SB latex, and by using a specific amount consisting of a specific phenolic antioxidant, gas yellowing resistance and heat aging resistance are further excellent and effective compared to conventional ones. .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 62-30172 (JP, A) JP 61-55134 (JP, A) JP 39-21115 (JP, B1)

Claims (2)

[Claims] 1. Emulsion polymerization of 20 to 70% by weight of an aliphatic conjugated diene, 0.5 to 8% by weight of an ethylenically unsaturated carboxylic acid, and 22 to 79.5% by weight of another monomer copolymerizable therewith. Phenolic antioxidant having a substituent having an ethylenic double bond, and having substituents at both ortho and para positions with respect to the phenolic hydroxyl group, relative to 100 parts by weight (solid content) of the resulting copolymerized latex. An adhesive for carpet backing, comprising 0.02 to 6 parts by weight and 0 to 750 parts by weight of a filler. 2. A phenolic antioxidant is represented by the general formula (I). Here, R ₁ and R ₂ are the same or different alkyl groups having 1 to 3 carbon atoms, and R ₃ and R ₄ are the same or different alkyl groups having 1 to 5 carbon atoms. Adhesive for carpet backing.